Materials

Research

16 pages, 3640 KiB

Open AccessArticle

Application of Silver Nanostructures Synthesized by Cold Atmospheric Pressure Plasma for Inactivation of Bacterial Phytopathogens from the Genera Dickeya and Pectobacterium

by Anna Dzimitrowicz^1,*,†

, Agata Motyka^2,†

, Piotr Jamroz¹

, Ewa Lojkowska²

, Weronika Babinska², Dominik Terefinko¹, Pawel Pohl^1,‡

and Wojciech Sledz^2,‡

¹ Department of Analytical Chemistry and Chemical Metallurgy, Faculty of Chemistry, Wroclaw University of Science and Technology, 27 Wybrzeze Wyspianskiego, 50-370 Wroclaw, Poland

² Department of Biotechnology, Intercollegiate Faculty of Biotechnology University of Gdansk and Medical University of Gdansk, University of Gdansk, 58 Abrahama, 80-307 Gdansk, Poland

^† These two authors contributed equally to this work.

^‡ These two authors also contributed equally to this work.

Materials 2018, 11(3), 331; https://doi.org/10.3390/ma11030331 - 25 Feb 2018

Cited by 27 | Viewed by 6745

Abstract

Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized [...] Read more.

Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized by pectins (PEC) or sodium dodecyl sulphate (SDS), using a direct current atmospheric pressure glow discharge (dc-APGD) generated in an open-to-air and continuous-flow reaction-discharge system. Characterization of the PEC-AgNPs and SDS-AgNPs with UV/Vis absorption spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed the production of spherical, well dispersed, and face cubic centered crystalline AgNPs, with average sizes of 9.33 ± 3.37 nm and 28.3 ± 11.7 nm, respectively. Attenuated total reflection-Fourier transformation infrared spectroscopy supported the functionalization of the nanostructures by PEC and SDS. Antibacterial activity of the AgNPs was tested against Dickeya spp. and Pectobacterium spp. strains. Both PEC-AgNPs and SDS-AgNPs displayed bactericidal activity against all of the tested isolates, with minimum inhibitory concentrations of 5.5 mg∙L⁻¹ and 0.75–3 mg∙L⁻¹, respectively. The collected results suggest that the dc-APGD reaction-discharge system can be applied for the production of defined AgNPs with strong antibacterial properties, which may be further applied in plant disease management. Full article

(This article belongs to the Special Issue Nanomaterials and Materials for Translational Research)

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10 pages, 8251 KiB

Open AccessArticle

Electrochemical Study of Polymer and Ceramic-Based Nanocomposite Coatings for Corrosion Protection of Cast Iron Pipeline

by Ameen Uddin Ammar¹, Muhammad Shahid¹, Muhammad Khitab Ahmed¹, Munawar Khan¹, Amir Khalid¹ and Zulfiqar Ahmad Khan^2,*

¹ School of Chemical & Materials Engineering, National University of Sciences & Technology, Islamabad 46000, Pakistan

² Bournemouth University, NanoCorr, Energy & Modelling (NCEM) Research Group, Poole House P123, Talbot Campus, Fern Barrow, Poole BH12 5BB, UK

Materials 2018, 11(3), 332; https://doi.org/10.3390/ma11030332 - 25 Feb 2018

Cited by 43 | Viewed by 7401

Abstract

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial [...] Read more.

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials are in marine environments and in the oil and gas industry. Knowing the corroding behavior of ferrous-based materials during exposure to these aggressive applications, an effort has been made to protect the material by using polymeric and ceramic-based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using the “three electrode system”. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyaniline/FLG (Few Layers Graphene) and TiO₂/GO (graphene oxide) nanocomposite by dip-coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and “produce water” of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples. Full article

(This article belongs to the Special Issue Wear-Corrosion Synergy, Nanocoating and Control of Materials)

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17 pages, 5905 KiB

Open AccessArticle

Synthesis, Characterization and In Vitro Study of Synthetic and Bovine-Derived Hydroxyapatite Ceramics: A Comparison

by July Andrea Rincón-López¹, Jennifer Andrea Hermann-Muñoz¹, Astrid Lorena Giraldo-Betancur¹

, Andrea De Vizcaya-Ruiz², Juan Manuel Alvarado-Orozco³ and Juan Muñoz-Saldaña^1,*

¹ Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Libramiento Norponiente #2000, Fraccionamiento Real de Juriquilla, Santiago de Querétaro 76230, Mexico

² Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Unidad Zacatenco, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, Delegación Gustavo A. Madero, Ciudad de Mexico 07360, Mexico

³ Centro de Ingeniería y Desarrollo Industrial, Av. Playa Pie de la Cuesta No. 702, Desarrollo San Pablo, Santiago de Querétaro 76125, Mexico

Materials 2018, 11(3), 333; https://doi.org/10.3390/ma11030333 - 25 Feb 2018

Cited by 62 | Viewed by 7076

Abstract

The physicochemical properties and biological behavior of sintered-bovine-derived hydroxyapatite (BHAp) are here reported and compared to commercial synthetic-HAp (CHAp). Dense ceramics were sintered for 2 h and 4 h at 1200 °C to investigate their microstructure–structure–in-vitro behavior relationship for both HAp ceramics. Densification [...] Read more.

The physicochemical properties and biological behavior of sintered-bovine-derived hydroxyapatite (BHAp) are here reported and compared to commercial synthetic-HAp (CHAp). Dense ceramics were sintered for 2 h and 4 h at 1200 °C to investigate their microstructure–structure–in-vitro behavior relationship for both HAp ceramics. Densification was directly proportional to sintering time, showing a grain coarsening behavior with a greater effect on BHAp. Lattice parameters, crystallite size, cell volume and Ca/P ratio were determined by Rietveld refinement of X-ray diffraction (XRD) patterns using GSAS^®. Ionic substitutions (Na⁺, Mg²⁺, CO₃²⁻) related to BHAp structure were associated with their position changes in the vibrational modes and correlated with the structural parameters obtained from the XRD analysis. Variations in the structural parameters and surface morphology were also evaluated after different soaking periods in simulated body fluid, which is associated with the formation of bone-like apatite layer and thus bioactivity. Mitochondrial activity (MTS) and lactate dehydrogenase (LDH) assays showed that the material released by the ceramics does not induce toxicity after exposure in human fetal osteoblastic (hFOB) cells. Furthermore, no statistically significant differences were found between the HAp obtained from different sources. These results show that BHAp can be used with no restrictions for the same biomedical applications as CHAp. Full article

(This article belongs to the Special Issue Bone Substitute Materials)

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15 pages, 6658 KiB

Open AccessArticle

Efficiency Evaluation of Food Waste Materials for the Removal of Metals and Metalloids from Complex Multi-Element Solutions

by Lorenzo Massimi^1,*

, Antonella Giuliano¹, Maria Luisa Astolfi¹

, Rossana Congedo², Andrea Masotti³ and Silvia Canepari¹

¹ Department of Chemistry, Sapienza University of Rome, Piazzale Aldo Moro, 5, 00185 Roma, Italy

² Istituto di Istruzione Superiore “Quinto Ennio”, Corso Roma, 100, 73014 Gallipoli, Italy

³ Children’s Hospital Bambino Gesù—IRCCS, Research Laboratories, Viale San Paolo, 15, 00145 Rome, Italy

Materials 2018, 11(3), 334; https://doi.org/10.3390/ma11030334 - 26 Feb 2018

Cited by 43 | Viewed by 5625

Abstract

Recent studies have shown the potential of food waste materials as low cost adsorbents for the removal of heavy metals and toxic elements from wastewater. However, the adsorption experiments have been performed in heterogeneous conditions, consequently it is difficult to compare the efficiency [...] Read more.

Recent studies have shown the potential of food waste materials as low cost adsorbents for the removal of heavy metals and toxic elements from wastewater. However, the adsorption experiments have been performed in heterogeneous conditions, consequently it is difficult to compare the efficiency of the individual adsorbents. In this study, the adsorption capacities of 12 food waste materials were evaluated by comparing the adsorbents’ efficiency for the removal of 23 elements from complex multi-element solutions, maintaining homogeneous experimental conditions. The examined materials resulted to be extremely efficient for the adsorption of many elements from synthetic multi-element solutions as well as from a heavy metal wastewater. The 12 adsorbent surfaces were analyzed by Fourier transform infrared spectroscopy and showed different types and amounts of functional groups, which demonstrated to act as adsorption active sites for various elements. By multivariate statistical computations of the obtained data, the 12 food waste materials were grouped in five clusters characterized by different elements’ removal efficiency which resulted to be in correlation with the specific adsorbents’ chemical structures. Banana peel, watermelon peel and grape waste resulted the least selective and the most efficient food waste materials for the removal of most of the elements. Full article

(This article belongs to the Section Biomaterials)

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10 pages, 3308 KiB

Open AccessArticle

New Insights into Mn_1−xZn_xFe₂O₄ via Fabricating Magnetic Photocatalyst Material BiVO₄/Mn_1−xZn_xFe₂O₄

by Taiping Xie^1,2

, Chenglun Liu^1,3,*, Longjun Xu¹ and Hui Li³

¹ State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

² Chongqing Key Laboratory of Extraordinary Bond Engineering and Advanced Materials Technology (EBEAM), Yangtze Normal University, Chongqing 408100, China

³ College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China

Materials 2018, 11(3), 335; https://doi.org/10.3390/ma11030335 - 26 Feb 2018

Cited by 15 | Viewed by 4142

Abstract

BiVO₄/Mn_1−xZn_xFe₂O₄ was prepared by the impregnation roasting method. XRD (X-ray Diffractometer) tests showed that the prepared BiVO₄ is monoclinic crystal, and the introduction of Mn_1−xZn_xFe₂O₄ does [...] Read more.

BiVO₄/Mn_1−xZn_xFe₂O₄ was prepared by the impregnation roasting method. XRD (X-ray Diffractometer) tests showed that the prepared BiVO₄ is monoclinic crystal, and the introduction of Mn_1−xZn_xFe₂O₄ does not change the crystal structure of BiVO₄. The introduction of a soft-magnetic material, Mn_1−xZn_xFe₂O₄, was beneficial to the composite photocatalyst’s separation from the liquid solution using an extra magnet after use. UV-vis spectra analysis indicated that Mn_1−xZn_xFe₂O₄ enhanced the absorption intensity of visible light for BiVO₄. EIS (electrochemical impedance spectroscopy) investigation revealed that the introduction of Mn_1−xZn_xFe₂O₄ enhanced the conductivity of BiVO₄, further decreasing its electron transfer impedance. The photocatalytic efficiency of BiVO₄/Mn_1−xZn_xFe₂O₄ was higher than that of pure BiVO₄. In other words, Mn_1−xZn_xFe₂O₄ could enhance the photocatalytic reaction rate. Full article

(This article belongs to the Special Issue Photocatalysis for Wastewater Treatment)

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14 pages, 2449 KiB

Open AccessArticle

Bond–Slip Relationship for CFRP Sheets Externally Bonded to Concrete under Cyclic Loading

by Ke Li^1,2, Shuangyin Cao³, Yue Yang^4,* and Juntao Zhu^1,*

¹ Department of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China

² Department of Civil Engineering, Tsinghua University, Beijing 100084, China

³ Department of Civil Engineering, Southeast University, Nanjing 210096, China

⁴ Department of Transportation Science and Engineering, Beihang University, Beijing 100191, China

Materials 2018, 11(3), 336; https://doi.org/10.3390/ma11030336 - 26 Feb 2018

Cited by 19 | Viewed by 5011

Abstract

The objective of this paper was to explore the bond–slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond–slip relationship under static [...] Read more.

The objective of this paper was to explore the bond–slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond–slip relationship under static and cyclic loading. The test variables are the CFRP-to-concrete width ratio, and the bond length of the CFRP sheets. An analysis of the test results in this paper and existing test results indicated that the slope of the ascending segment of the bond–slip curve decreased with an increase in the number of load cycles, but the slip corresponding to the maximum shear stress was almost invariable as the number of load cycles increased. In addition, the rate of reduction in the slope of the ascending range of the bond–slip curve during cyclic loading decreased as the concrete strength increased, and increased as the load level or CFRP-to-concrete width ratio enhanced. However, these were not affected by variations in bond length if the residual bond length was longer than the effective bond length. A bilinear bond–slip model for CFRP sheets that are externally bonded to concrete under cyclic loading, which considered the effects of the cyclic load level, concrete strength, and CFRP-to-concrete ratio, was developed based on the existing static bond–slip model. The accuracy of this proposed model was verified by a comparison between this proposed model and test results. Full article

(This article belongs to the Special Issue Carbon Fiber Reinforced Polymers)

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9 pages, 5711 KiB

Open AccessArticle

Strain-Compensated InGaAsP Superlattices for Defect Reduction of InP Grown on Exact-Oriented (001) Patterned Si Substrates by Metal Organic Chemical Vapor Deposition

by Ludovico Megalini^1,*, Simone Tommaso Šuran Brunelli¹, William O. Charles², Aidan Taylor³, Brandon Isaac³, John E. Bowers^1,3

and Jonathan Klamkin¹

¹ Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA

² SUNY Polytechnic Institute, Albany, NY 12222, USA

³ Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA

Materials 2018, 11(3), 337; https://doi.org/10.3390/ma11030337 - 26 Feb 2018

Cited by 14 | Viewed by 5839

Abstract

We report on the use of InGaAsP strain-compensated superlattices (SC-SLs) as a technique to reduce the defect density of Indium Phosphide (InP) grown on silicon (InP-on-Si) by Metal Organic Chemical Vapor Deposition (MOCVD). Initially, a 2 μm thick gallium arsenide (GaAs) layer was [...] Read more.

We report on the use of InGaAsP strain-compensated superlattices (SC-SLs) as a technique to reduce the defect density of Indium Phosphide (InP) grown on silicon (InP-on-Si) by Metal Organic Chemical Vapor Deposition (MOCVD). Initially, a 2 μm thick gallium arsenide (GaAs) layer was grown with very high uniformity on exact oriented (001) 300 mm Si wafers; which had been patterned in 90 nm V-grooved trenches separated by silicon dioxide (SiO₂) stripes and oriented along the [110] direction. Undercut at the Si/SiO₂ interface was used to reduce the propagation of defects into the III–V layers. Following wafer dicing; 2.6 μm of indium phosphide (InP) was grown on such GaAs-on-Si templates. InGaAsP SC-SLs and thermal annealing were used to achieve a high-quality and smooth InP pseudo-substrate with a reduced defect density. Both the GaAs-on-Si and the subsequently grown InP layers were characterized using a variety of techniques including X-ray diffraction (XRD); atomic force microscopy (AFM); transmission electron microscopy (TEM); and electron channeling contrast imaging (ECCI); which indicate high-quality of the epitaxial films. The threading dislocation density and RMS surface roughness of the final InP layer were 5 × 10⁸/cm² and 1.2 nm; respectively and 7.8 × 10⁷/cm² and 10.8 nm for the GaAs-on-Si layer. Full article

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12 pages, 3831 KiB

Open AccessArticle

Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

by Zi-Kun Rao

, Rui Chen, Hong-Yu Zhu, Yang Li, Yu Liu and Jian-Yuan Hao^*

School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, No.4, Section 2, North Jian’she Road, Chengdu 610054, China

Materials 2018, 11(3), 338; https://doi.org/10.3390/ma11030338 - 26 Feb 2018

Cited by 9 | Viewed by 4144

Abstract

To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (ε-caprolactone-co-p-dioxanone)-b-poly (ethylene glycol)-b-poly (ε-caprolactone-co-p-dioxanone) (PECP) was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent [...] Read more.

To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (ε-caprolactone-co-p-dioxanone)-b-poly (ethylene glycol)-b-poly (ε-caprolactone-co-p-dioxanone) (PECP) was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent reversible sol-gel transition in water. The carboxylic end group could significantly decrease the sol-gel transition temperature by nearly 10 °C and strengthen the gel due to enhanced intermolecular force among triblock copolymer chains. Furthermore, compared with the original PECP triblock copolymer, HOOC–PECP–COOH copolymer displayed a retarded and sustained release profile for leuprorelin acetate over one month while effectively avoiding the initial burst. The controlled release was believed to be related to the formation of conjugated copolymer-peptide pair by ionic interaction and enhanced solubility of drug molecules into the hydrophobic domains of the hydrogel. Therefore, carboxyl terminated HOOC–PECP–COOH hydrogel was a promising and well-exhibited sustained release carrier for peptide drugs with the advantage of being able to develop injectable formulation by simple mixing. Full article

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11 pages, 6355 KiB

Open AccessArticle

Critical Current Simulation and Measurement of Second Generation, High-Temperature Superconducting Coil under External Magnetic Field

by Dongmin Yu¹

, Huanan Liu^1,*

, Xinhe Zhang² and Taorong Gong²

¹ Department of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China

² China Electric Power Research Institute, Beijing 100192, China

Materials 2018, 11(3), 339; https://doi.org/10.3390/ma11030339 - 26 Feb 2018

Cited by 10 | Viewed by 4747

Abstract

This paper studies the critical current of second generation, high temperature superconducting coils under an external magnetic field experimentally and numerically. Two identical coils with different coated conductors are fabricated and tested under a direct current (DC) magnetic field along the axis of [...] Read more.

This paper studies the critical current of second generation, high temperature superconducting coils under an external magnetic field experimentally and numerically. Two identical coils with different coated conductors are fabricated and tested under a direct current (DC) magnetic field along the axis of the coil. Then, a numerical model in cylindrical coordinates based on a sheet current model is built by taking the measured magnetic field dependency to analyze the current distribution and magnetic field distribution. The simulated critical currents of the coils under the DC magnetic field have good agreement with the measured results. We find that under the in-phase field, the critical current decreases as the magnetic field in the innermost turn is enhanced by the external field. Meanwhile, the anti-phase external field increases the critical current a bit at first, then decreases the critical current. We further discuss the critical current criteria of the coils, showing that the parallel field plays a more important role in critical current determination. Full article

(This article belongs to the Section Thin Films and Interfaces)

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12 pages, 4046 KiB

Open AccessArticle

High Efficient Reduction of Graphene Oxide via Nascent Hydrogen at Room Temperature

by Qiqi Zhuo¹, Jijun Tang¹, Jun Sun² and Chao Yan^1,*

¹ College of Material Science & Engineering, Jiangsu University of Science and Technology, 2 Meng-Xi Road, Zhenjiang 212003, China

² College of Chemistry, Chemical Engineering and Material Science, Soochow University, 199 Ren-Ai Road, Suzhou 215123, China

Materials 2018, 11(3), 340; https://doi.org/10.3390/ma11030340 - 27 Feb 2018

Cited by 11 | Viewed by 5513

Abstract

To develop a green and efficient method to synthesize graphene in relative milder conditions is prerequisite for graphene applications. A chemical reducing method has been developed to high efficiently reduce graphene oxide (GO) using Fe₂O₃ and NH₃BH₃ [...] Read more.

To develop a green and efficient method to synthesize graphene in relative milder conditions is prerequisite for graphene applications. A chemical reducing method has been developed to high efficiently reduce graphene oxide (GO) using Fe₂O₃ and NH₃BH₃ as catalyst and reductants, respectively. During the process, environmental and strong reductive nascent hydrogen were generated surrounding the surface of GO sheets by catalyst hydrolysis reaction of NH₃BH₃ and were used for reduction of GO. The reduction process was studied by ultraviolet absorption spectroscopy, Raman spectroscopy, and Fourier transform infrared spectrum. The structure and morphology of the reduced GO were characterized with scanning electron microscopy and transmission electron microscopy. Compared to metal (Mg/Fe/Zn/Al) particles and acid system which also use nascent hydrogen to reduce GO, this method exhibited higher reduction efficiency (43.6%). Also the reduction was carried out at room temperature condition, which is environmentally friendly. As a supercapacitor electrode, the reversible capacity of reduced graphene oxide was 113.8 F g⁻¹ at 1 A g⁻¹ and the capacitance retention still remained at 90% after 200 cycles. This approach provides a new method to reduce GO with high reduction efficiency by green reductant. Full article

(This article belongs to the Section Carbon Materials)

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14 pages, 1983 KiB

Open AccessArticle

Comparison of Six Different Silicones In Vitro for Application as Glaucoma Drainage Device

by Claudia Windhövel¹, Lisa Harder¹, Jan-Peter Bach¹, Michael Teske², Niels Grabow², Thomas Eickner², Ulf Hinze³

, Boris Chichkov^3,4 and Ingo Nolte^1,*

¹ Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, D-30559 Hannover, Germany

² Institute for Biomedical Engineering, Rostock University Medical Center, D-18119 Rostock, Germany

³ Laser Zentrum Hannover e.V., D-30419 Hannover, Germany

⁴ Leibniz Universität Hannover, D-30167 Hannover, Germany

Materials 2018, 11(3), 341; https://doi.org/10.3390/ma11030341 - 27 Feb 2018

Cited by 8 | Viewed by 4438

Abstract

Silicones are widely used in medical applications. In ophthalmology, glaucoma drainage devices are utilized if conservative therapies are not applicable or have failed. Long-term success of these devices is limited by failure to control intraocular pressure due to fibrous encapsulation. Therefore, different medical [...] Read more.

Silicones are widely used in medical applications. In ophthalmology, glaucoma drainage devices are utilized if conservative therapies are not applicable or have failed. Long-term success of these devices is limited by failure to control intraocular pressure due to fibrous encapsulation. Therefore, different medical approved silicones were tested in vitro for cell adhesion, cell proliferation and viability of human Sclera (hSF) and human Tenon fibroblasts (hTF). The silicones were analysed also depending on the sample preparation according to the manufacturer’s instructions. The surface quality was characterized with environmental scanning electron microscope (ESEM) and water contact angle measurements. All silicones showed homogeneous smooth and hydrophobic surfaces. Cell adhesion was significantly reduced on all silicones compared to the negative control. Proliferation index and cell viability were not influenced much. For development of a new glaucoma drainage device, the silicones Silbione LSR 4330 and Silbione LSR 4350, in this study, with low cell counts for hTF and low proliferation indices for hSF, and silicone Silastic MDX4-4210, with low cell counts for hSF and low proliferation indices for hTF, have shown the best results in vitro. Due to the high cell adhesion shown on Silicone LSR 40, 40,026, this material is unsuitable. Full article

(This article belongs to the Section Biomaterials)

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12 pages, 6147 KiB

Open AccessArticle

Microstructure Evolution during Dissimilar Friction Stir Welding of AA7003-T4 and AA6060-T4

by Jialiang Dong, Datong Zhang^*, Weiwen Zhang, Wen Zhang and Cheng Qiu

National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China

Materials 2018, 11(3), 342; https://doi.org/10.3390/ma11030342 - 27 Feb 2018

Cited by 27 | Viewed by 4530

Abstract

In this work, the dissimilar joint of AA7003-T4 and 6060-T4 alloy has been produced by friction stir welding (FSW). The microstructure was examined by optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and the mechanical properties of the joint [...] Read more.

In this work, the dissimilar joint of AA7003-T4 and 6060-T4 alloy has been produced by friction stir welding (FSW). The microstructure was examined by optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and the mechanical properties of the joint were investigated. It is demonstrated that sound dissimilar joint can be produced through FSW. In the nugget; precipitations dissolve into the matrix and η′ reprecipitate subsequently; and the elongated aluminum grains are replaced by fine and equiaxed grains due to dynamic recrystallization (DRX). In the heat affected zone (HAZ), coarse β′ and η precipitates are formed and the aluminum grains are coarser as compared to the base materials. In the thermo-mechanical affected zone (TMAZ), equiaxed and elongated grains coexist due to incomplete DRX. The ultimate tensile strength of the dissimilar joint is 159.2 MPa and its elongation is 10.4%. The weak area exists in the HAZ of 6060 alloy, which is placed in the retreating side during FSW. The correlations between the microstucture and mechanical properties of the dissimilar joint are discussed. Full article

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12 pages, 3124 KiB

Open AccessArticle

Fabrication of Completely Polymer-Based Solar Cells with p- and n-Type Semiconducting Block Copolymers with Electrically Inert Polystyrene

by Eri Tomita, Shinji Kanehashi and Kenji Ogino^*

Graduate School of Bio-Applications Systems Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan

Materials 2018, 11(3), 343; https://doi.org/10.3390/ma11030343 - 27 Feb 2018

Cited by 7 | Viewed by 4178

Abstract

It is widely recognized that fullerene derivatives show several advantages as n-type materials in photovoltaic applications. However, conventional [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) exhibits weak absorption in the visible region, and poor morphological stability, due to the facile aggregation. For further improvement of [...] Read more.

It is widely recognized that fullerene derivatives show several advantages as n-type materials in photovoltaic applications. However, conventional [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) exhibits weak absorption in the visible region, and poor morphological stability, due to the facile aggregation. For further improvement of the device performance and durability, utilization of n-type polymeric materials instead of PCBM is considered to be a good way to solve the problems. In this study, we fabricated completely polymer-based solar cells utilizing p- and n-type block copolymers consisting of poly(3-hexylthiophene) (P3HT) and poly{[N,N′-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI2OD-T2)], respectively, containing common polystyrene (PSt) inert blocks, which decreased the size of phase separated structures. Electron mobility in synthesized P(NDI2OD-T2)-b-PSt film enhanced by a factor of 8 compared with homopolymer. The root mean square roughness of the blend film of two block copolymers (12.2 nm) was decreased, compared with that of the simple homopolymers blend (18.8 nm). From the current density-voltage characteristics, it was confirmed that the introduction of PSt into both P3HT and P(NDI2OD-T2) improves short-circuit current density (1.16 to 1.73 mA cm⁻²) and power-conversion efficiency (0.24% to 0.32%). Better performance is probably due to the uniformity of the phase separation, and the enhancement of charge mobility. Full article

(This article belongs to the Special Issue Extraordinary Structures and Physicochemical Properties of Nanomaterials—Select Papers from ICNNN 2017)

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13 pages, 4329 KiB

Open AccessArticle

Investigation of Zinc and Phosphorus Elements Incorporated into Micro-Arc Oxidation Coatings Developed on Ti-6Al-4V Alloys

by Yaping Wang^1,2,†, Lilan Zeng^2,†, Honghua Zhang¹, Junhuai Xiang¹, Shufang Zhang¹, Wenhui Chang¹, Rongfa Zhang^1,*, Qiao Wang¹, Yang Sheng¹ and Ying Zhao^2,*

¹ School of Materials and Electromechanics, Jiangxi Science and Technology Normal University, Nanchang 330013, China

² Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China

^† These authors contributed equally to this study.

Materials 2018, 11(3), 344; https://doi.org/10.3390/ma11030344 - 27 Feb 2018

Cited by 24 | Viewed by 4478

Abstract

In order to clarify the mechanism that zinc and phosphorus elements entering the micro-arc oxidation (MAO) coatings developed on Ti-6Al-4V alloys, anodic coatings containing different zinc and phosphorus were fabricated using an orthogonal experiment of four factors with three levels in an electrolyte [...] Read more.

In order to clarify the mechanism that zinc and phosphorus elements entering the micro-arc oxidation (MAO) coatings developed on Ti-6Al-4V alloys, anodic coatings containing different zinc and phosphorus were fabricated using an orthogonal experiment of four factors with three levels in an electrolyte containing EDTA-ZnNa₂, KOH, and phytic acid. Surface morphology, element composition, chemical state and phase structure of MAO coatings were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The concentrations of zinc and phosphorus in the electrolyte were analyzed by an inductively coupled plasma optical emission spectrometry (ICP-OES). The results show that zinc and phosphorus elements in MAO coatings exist in the form of Zn₃(PO₄)₂. Phytic acid is the most important factor on both zinc and phosphorus contents of MAO coatings. With the increase of phytic acid concentration or the decrease of KOH concentration, the contents of zinc and phosphorus in MAO coatings present a similarly increasing tendency. Our results indicate that phosphorus takes part in coating formation mainly by diffusion, while zinc enters into MAO coatings with phosphorus from phytic acid. Full article

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11 pages, 2571 KiB

Open AccessArticle

Current Modulation of a Heterojunction Structure by an Ultra-Thin Graphene Base Electrode

by Carlos Alvarado Chavarin^1,*, Carsten Strobel², Julia Kitzmann¹, Antonio Di Bartolomeo³

, Mindaugas Lukosius¹

, Matthias Albert², Johann Wolfgang Bartha² and Christian Wenger^1,4

¹ IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany

² Technische Universität Dresden, Semiconductor and Microsystems Technology Laboratory, 01062 Dresden, Germany

³ Physics Department E R Caianiello, University of Salerno, via Giovanni Paolo II, I-84084 Fisciano, Salerno, Italy

⁴ Medical High School Theodor Fontane, 16816 Neuruppin, Germany

Materials 2018, 11(3), 345; https://doi.org/10.3390/ma11030345 - 27 Feb 2018

Cited by 13 | Viewed by 4707

Abstract

Graphene has been proposed as the current controlling element of vertical transport in heterojunction transistors, as it could potentially achieve high operation frequencies due to its metallic character and 2D nature. Simulations of graphene acting as a thermionic barrier between the transport of [...] Read more.

Graphene has been proposed as the current controlling element of vertical transport in heterojunction transistors, as it could potentially achieve high operation frequencies due to its metallic character and 2D nature. Simulations of graphene acting as a thermionic barrier between the transport of two semiconductor layers have shown cut-off frequencies larger than 1 THz. Furthermore, the use of n-doped amorphous silicon, (n)-a-Si:H, as the semiconductor for this approach could enable flexible electronics with high cutoff frequencies. In this work, we fabricated a vertical structure on a rigid substrate where graphene is embedded between two differently doped (n)-a-Si:H layers deposited by very high frequency (140 MHz) plasma-enhanced chemical vapor deposition. The operation of this heterojunction structure is investigated by the two diode-like interfaces by means of temperature dependent current-voltage characterization, followed by the electrical characterization in a three-terminal configuration. We demonstrate that the vertical current between the (n)-a-Si:H layers is successfully controlled by the ultra-thin graphene base voltage. While current saturation is yet to be achieved, a transconductance of ~230

μ S

was obtained, demonstrating a moderate modulation of the collector-emitter current by the ultra-thin graphene base voltage. These results show promising progress towards the application of graphene base heterojunction transistors. Full article

(This article belongs to the Special Issue Recent Advances in 2D Nanomaterials)

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14 pages, 32338 KiB

Open AccessArticle

Residual Tensile Strength and Bond Properties of GFRP Bars after Exposure to Elevated Temperatures

by Devon S. Ellis¹, Habib Tabatabai^2,*

and Azam Nabizadeh²

¹ Ellis Engineering & Construction Management Services, LLC, Milwaukee, WI 53212, USA

² Department of Civil and Environmental Engineering, University of Wisconsin, Milwaukee, WI 53211, USA

Materials 2018, 11(3), 346; https://doi.org/10.3390/ma11030346 - 27 Feb 2018

Cited by 60 | Viewed by 7292

Abstract

The use of fiber reinforced polymer (FRP) bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated [...] Read more.

The use of fiber reinforced polymer (FRP) bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated temperatures (due to fire), there is little published information available on their post-fire residual load capacity. This paper reports residual tensile strength, modulus of elasticity, and bond strength (to concrete) of glass fiber reinforced polymer (GFRP) bars after exposure to elevated temperatures of up to 400 °C and subsequent cooling to an ambient temperature. The results showed that the residual strength generally decreases with increasing temperature exposure. However, as much as 83% of the original tensile strength and 27% of the original bond strength was retained after the specimens were heated to 400 °C and then cooled to ambient temperature. The residual bond strength is a critical parameter in post-fire strength assessments of GFRP-reinforced concrete members. Full article

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14 pages, 3974 KiB

Open AccessArticle

A Facile Strategy to Enhance the Dielectric and Mechanical Properties of MWCNTs/PVDF Composites with the Aid of MMA-co-GMA Copolymer

by Shixin Song¹, Shan Xia¹, Shangkun Jiang¹, Xue Lv¹, Shulin Sun^1,* and Quanming Li^2,*

¹ Engineering Research Center of Synthetic Resin and Special Fiber, Ministry of Education, Changchun University of Technology, Changchun 130012, China

² Key Laboratory of Automobile Materials, College of Materials Science & Engineering, Jilin University, Changchun 130025, China

Materials 2018, 11(3), 347; https://doi.org/10.3390/ma11030347 - 27 Feb 2018

Cited by 22 | Viewed by 4313

Abstract

A facile strategy is adopted to prepare carboxylic functionalized multiwalled carbon nanotube (c-MWCNT) modified high dielectric constant (high-k) poly(vinylidene fluoride) (PVDF) composites with the aid of methyl methacrylate-co-glycidyl methacrylate copolymer (MG). The MG is miscible with PVDF and the epoxy groups [...] Read more.

A facile strategy is adopted to prepare carboxylic functionalized multiwalled carbon nanotube (c-MWCNT) modified high dielectric constant (high-k) poly(vinylidene fluoride) (PVDF) composites with the aid of methyl methacrylate-co-glycidyl methacrylate copolymer (MG). The MG is miscible with PVDF and the epoxy groups of the copolymer can react with the carboxylic groups of c-MWCNT, which induce the uniform dispersion of c-MWCNT and a form insulator layer on the surface of c-MWCNT. The c-MWCNTs/MG/PVDF composites with 8 vol % c-MWCNT present excellent dielectric properties with high dielectric constant (~448) and low dielectric loss (~2.36) at the frequency of 1 KHz, the dielectric loss is much lower than the c-MWCNT/PVDF composites without MG. The obvious improvement in dielectric properties ascribes to the existence of MG, which impede the direct contact of c-MWCNTs and PVDF and avoid the formation of conductive network. Therefore, we propose a practical and simple strategy for preparing composites with excellent dielectric properties, which are promising for applications in electronics devices. Full article

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9 pages, 5307 KiB

Open AccessArticle

Comparison of Commercial Calcium Hydroxide Pastes for Prolonged Antibacterial Effect using a Colourimetric Assessment

by Yu-Yao Teoh^1,*

, Basil Athanassiadis² and Laurence J. Walsh¹

¹ School of Dentistry, The University of Queensland, Herston, QLD 4006, Australia

² Private Dental Practice, Annerley, QLD 4103, Australia

Materials 2018, 11(3), 348; https://doi.org/10.3390/ma11030348 - 27 Feb 2018

Cited by 13 | Viewed by 4236

Abstract

The anti-microbial activity of calcium hydroxide pastes used in endodontics is dependent on establishing high levels of hydroxyl ions in dentine. This study investigated hydroxyl ion diffusion from different commercial calcium hydroxide pastes using a novel colourimetric method. In this method, human tooth [...] Read more.

The anti-microbial activity of calcium hydroxide pastes used in endodontics is dependent on establishing high levels of hydroxyl ions in dentine. This study investigated hydroxyl ion diffusion from different commercial calcium hydroxide pastes using a novel colourimetric method. In this method, human tooth roots were stained with anthocyanin dye, which changed their colour according to the local pH conditions. Prepared root canals were filled with pastes formulated with the vehicle of water (Pulpdent™, Calasept Plus™), polyethylene glycol (PEG) (Calmix™) or a mixture of water, PEG and ibuprofen (Odontocide™). The changes in dye colour at fixed distances from the canal wall were monitored using standardised digital photography over a period of 3 weeks. A repeated measures analysis tracked changes in each root from baseline. Release of hydroxyl ions varied between the different commercial compositions containing water or PEG as solvents. The colour changes in the dentine, due to released hydroxyl ions, were greatest and more prolonged for completely non-aqueous compositions, when using PEG 400 as the vehicle. When water was present in the product, the duration of the pH changes was shorter. This was attributed to the presence of hydroxyl ions in the water (the common-ion effect) and a more vigorous buffering of hydroxyl ions by dentine proteins. Full article

(This article belongs to the Special Issue Dental Biomaterials 2017)

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13 pages, 4768 KiB

Open AccessFeature PaperArticle

Bioactive Glass-Ceramic Foam Scaffolds from ‘Inorganic Gel Casting’ and Sinter-Crystallization

by Hamada Elsayed^1,2

, Acacio Rincón Romero¹

, Giulia Molino³, Chiara Vitale Brovarone³ and Enrico Bernardo^1,*

¹ Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy

² Ceramics Department, National Research Centre, El-Bohous Street, Cairo 12622, Egypt

³ Dipartimento Scienza Applicata e Tecnologia, Politecnico di Torino, 10129 Torino, Italy

Materials 2018, 11(3), 349; https://doi.org/10.3390/ma11030349 - 27 Feb 2018

Cited by 25 | Viewed by 6278

Abstract

Highly porous bioactive glass-ceramic scaffolds were effectively fabricated by an inorganic gel casting technique, based on alkali activation and gelification, followed by viscous flow sintering. Glass powders, already known to yield a bioactive sintered glass-ceramic (CEL2) were dispersed in an alkaline solution, with [...] Read more.

Highly porous bioactive glass-ceramic scaffolds were effectively fabricated by an inorganic gel casting technique, based on alkali activation and gelification, followed by viscous flow sintering. Glass powders, already known to yield a bioactive sintered glass-ceramic (CEL2) were dispersed in an alkaline solution, with partial dissolution of glass powders. The obtained glass suspensions underwent progressive hardening, by curing at low temperature (40 °C), owing to the formation of a C–S–H (calcium silicate hydrate) gel. As successful direct foaming was achieved by vigorous mechanical stirring of gelified suspensions, comprising also a surfactant. The developed cellular structures were later heat-treated at 900–1000 °C, to form CEL2 glass-ceramic foams, featuring an abundant total porosity (from 60% to 80%) and well-interconnected macro- and micro-sized cells. The developed foams possessed a compressive strength from 2.5 to 5 MPa, which is in the range of human trabecular bone strength. Therefore, CEL2 glass-ceramics can be proposed for bone substitutions. Full article

(This article belongs to the Special Issue Bioactive Glasses 2017)

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12 pages, 5706 KiB

Open AccessArticle

Fabrication and Anti-Oxidation Ability of SiC-SiO₂ Coated Carbon Fibers Using Sol-Gel Method

by Guangyuan Yang^*, Zhixiong Huang, Xu Wang and Bo Wang

Department of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China

Materials 2018, 11(3), 350; https://doi.org/10.3390/ma11030350 - 27 Feb 2018

Cited by 22 | Viewed by 5979

Abstract

The paper proposed a method to improve the anti-oxidation performance of carbon fibers (CF) at high temperature environment by coating silicon dioxide (SiO₂) and silicon carbide (SiC). The modified sol-gel method had been used to ensure the proper interface between fibers [...] Read more.

The paper proposed a method to improve the anti-oxidation performance of carbon fibers (CF) at high temperature environment by coating silicon dioxide (SiO₂) and silicon carbide (SiC). The modified sol-gel method had been used to ensure the proper interface between fibers and coating. We used polydimethylsiloxane and ethyl orthosilicate to make stable emulsion to uniformly disperse SiC nanoparticles. The modified SiO₂/SiC coating had been coated on CF successfully. Compared with the untreated CF, the coated fibers started to be oxidized around 900 °C and the residual weight was 57% at 1400 °C. The oxidation mechanism had been discussed. The structure of SiC/SiO₂ coated CF had been characterized by scanning electron microscope and X-ray diffraction analysis. Thermal gravimetric analysis was used to test the anti-oxidation ability of CF with different coatings. Full article

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13 pages, 4462 KiB

Open AccessFeature PaperArticle

Optical Properties of Complex Plasmonic Materials Studied with Extended Effective Medium Theories Combined with Rigorous Coupled Wave Analysis

by Elie Nadal^1,2,*

, Noémi Barros^1,2, Hervé Glénat² and Hamid Kachakachi^1,2

¹ University of Perpignan Via Domitia (UPVD), 52 Avenue Paul Alduy, 66100 Perpignan, France

² Processes, Materials, and Solar Energy Laboratory, CNRS (PROMES-CNRS, UPR 8521), Rambla de la Thermodynamique, 66100 Perpignan, France

Materials 2018, 11(3), 351; https://doi.org/10.3390/ma11030351 - 27 Feb 2018

Cited by 8 | Viewed by 5435

Abstract

In this study we fabricate gold nanocomposites and model their optical properties. The nanocomposites are either homogeneous films or gratings containing gold nanoparticles embedded in a polymer matrix. The samples are fabricated using a recently developed technique making use of laser interferometry. The [...] Read more.

In this study we fabricate gold nanocomposites and model their optical properties. The nanocomposites are either homogeneous films or gratings containing gold nanoparticles embedded in a polymer matrix. The samples are fabricated using a recently developed technique making use of laser interferometry. The gratings present original plasmon-enhanced diffraction properties. In this work, we develop a new approach to model the optical properties of our composites. We combine the extended Maxwell–Garnett model of effective media with the Rigorous Coupled Wave Analysis (RCWA) method and compute both the absorption spectra and the diffraction efficiency spectra of the gratings. We show that such a semi-analytical approach allows us to reproduce the original plasmonic features of the composites and can provide us with details about their inner structure. Such an approach, considering reasonably high particle concentrations, could be a simple and efficient tool to study complex micro-structured system based on plasmonic components, such as metamaterials. Full article

(This article belongs to the Special Issue Latest Nanotechnology Research Output 2017—Select papers from Applied Nanotechnology and Nanoscience International Conference—ANNIC 2017)

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19 pages, 5321 KiB

Open AccessArticle

Polyurethanes Crosslinked with Poly(vinyl alcohol) as a Slowly-Degradable and Hydrophilic Materials of Potential Use in Regenerative Medicine

by Justyna Kucińska-Lipka

Department of Polymers Technology, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdansk, Poland

Materials 2018, 11(3), 352; https://doi.org/10.3390/ma11030352 - 27 Feb 2018

Cited by 18 | Viewed by 4399

Abstract

Novel, slowly-degradable and hydrophilic materials with proper mechanical properties and surface characteristics are in great demand within the biomedical field. In this paper, the design, synthesis, and characterization of polyurethanes (PUR) crosslinked with poly(vinyl alcohol) (PVA) as a new proposition for regenerative medicine [...] Read more.

Novel, slowly-degradable and hydrophilic materials with proper mechanical properties and surface characteristics are in great demand within the biomedical field. In this paper, the design, synthesis, and characterization of polyurethanes (PUR) crosslinked with poly(vinyl alcohol) (PVA) as a new proposition for regenerative medicine is described. PVA-crosslinked PURs were synthesized by a two-step polymerization performed in a solvent (dimethylsulfoxide, DMSO). The raw materials used for the synthesis of PVA-crosslinked PURs were poly(ε-caprolactone) (PCL), 1,6-hexamethylene diisocyanate (HDI), and PVA as a crosslinking agent. The obtained materials were studied towards their physicochemical, mechanical, and biological performance. The tests revealed contact angle of the materials surface between 38–47° and tensile strength in the range of 41–52 MPa. Mechanical characteristics of the obtained PURs was close to the characteristics of native human bone such as the cortical bone (T_Sb = 51–151 MPa) or the cancellous bone (T_Sb = 10–20 MPa). The obtained PVA-crosslinked PURs did not show significant progress of degradation after 3 months of incubation in a phosphate-buffered saline (PBS). Accordingly, the obtained materials may behave similar to slowly-degradable materials, which can provide long-term physical support in, for example, tissue regeneration, as well as providing a uniform calcium deposition on the material surface, which may influence, for example, bone restoration. A performed short-term hemocompatibility study showed that obtained PVA-crosslinked PURs do not significantly influence blood components, and a cytotoxicity test performed with the use of MG 63 cell line revealed the great cytocompatibility of the obtained materials. According to the performed studies, such PVA-crosslinked PURs may be a suitable proposition for the field of tissue engineering in regenerative medicine. Full article

(This article belongs to the Section Biomaterials)

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14 pages, 4753 KiB

Open AccessArticle

Innovative Chemical Process for Recycling Thermosets Cured with Recyclamines^® by Converting Bio-Epoxy Composites in Reusable Thermoplastic—An LCA Study

by Angela D. La Rosa^1,*

, Ignazio Blanco^1,*

, Diosdado R. Banatao², Stefan J. Pastine², Anna Björklund³

and Gianluca Cicala¹

¹ Department of Civil Engineering and Architecture and INSTM UdR, University of Catania, Viale A. Doria 6, 95125 Catania, Italy

² Connora Technologies Inc., 30621 San Antonio St, Hayward, CA 94544, USA

³ Environmental Strategies Research-fms, Royal Institute of Technology, KTH, 100-44 Stockholm, Sweden

Materials 2018, 11(3), 353; https://doi.org/10.3390/ma11030353 - 28 Feb 2018

Cited by 70 | Viewed by 8114

Abstract

An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA) was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the [...] Read more.

An innovative recycling process for thermoset polymer composites developed by Connora Technologies (Hayward, CA, USA) was studied. The process efficacy has already been tested, and it is currently working at the plant level. The main aspect investigated in the present paper was the environmental impact by means of the Life Cycle Assessment (LCA) method. Because of the need to recycle and recover materials at their end of life, the Connora process creates a great innovation in the market of epoxy composites, as they are notoriously not recyclable. Connora Technologies developed a relatively gentle chemical recycling process that induces the conversion of thermosets into thermoplastics. The LCA demonstrated that low environmental burdens are associated with the process itself and, furthermore, impacts are avoided due to the recovery of the epoxy-composite constituents (fibres and matrix). A carbon fibre (CF) epoxy-composite panel was produced through Vacuum Resin Transfer Moulding (VRTM) and afterwards treated using the Connora recycling process. The LCA results of both the production and the recycling phases are reported. Full article

(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)

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15 pages, 6996 KiB

Open AccessArticle

Carbon Nanotubes Reinforced Maleic Anhydride-Modified Xylan-g-Poly(N-isopropylacrylamide) Hydrogel with Multifunctional Properties

by Xinxin Liu¹, Tao Song¹, Minmin Chang¹, Ling Meng¹, Xiaohui Wang¹, Runcang Sun² and Junli Ren^1,3,*

¹ State Key Laboratory of Pulp and Paper Engineering, School of Light Industry and Engineering, South China University of Technology, Guangzhou 510640, China

² Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China

³ Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education, Qilu University of Technology, Jinan 250353, China

Materials 2018, 11(3), 354; https://doi.org/10.3390/ma11030354 - 28 Feb 2018

Cited by 79 | Viewed by 6021

Abstract

Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified [...] Read more.

Introducing multifunctional groups and inorganic material imparts xylan-based hydrogels with excellent properties, such as responsiveness to pH, temperature, light, and external magnetic field. In this work, a composite hydrogel was synthesized by introducing acid treated carbon nanotubes (AT-CNTs) into the maleic anhydride modified xylan grafted with poly(N-isopropylacrylamide) (MAX-g-PNIPAM) hydrogels network. It was found that the addition of AT-CNTs affected the MAX-g-PNIPAM hydrogel structure, the swelling ratio and mechanical properties, and imparted the hydrogel with new properties of electrical conductivity and near infrared region (NIR) photothermal conversion. AT-CNTs could reinforce the mechanical properties of MAX-g-PNIPAM hydrogels, being up to 83 kPa for the compressive strength when the amount was 11 wt %, which was eight times than that of PNIPAM hydrogel and four times than that of MAX-g-PNIPAM hydrogel. The electroconductibility was enhanced by the increase of AT-CNTs amounts. Meanwhile, the composite hydrogel also exhibited multiple shape memory and NIR photothermal conversion properties, and water temperature was increased from 26 °C to 56 °C within 8 min under the NIR irradiation. Thus, the AT-CNTs reinforced MAX-g-PNIPAM hydrogel possessed promising multifunctional properties, which offered many potential applications in the fields of biosensors, thermal-arrest technology, and drug-controlled release. Full article

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10 pages, 3129 KiB

Open AccessArticle

Enhanced Charge Extraction of Li-Doped TiO₂ for Efficient Thermal-Evaporated Sb₂S₃ Thin Film Solar Cells

by Chunfeng Lan^1,2,3,†, Jingting Luo^1,3,†, Huabin Lan^1,3, Bo Fan^1,3, Huanxin Peng^1,3, Jun Zhao^1,3, Huibin Sun^1,2, Zhuanghao Zheng^1,3, Guangxing Liang^1,3,* and Ping Fan^1,3,*

¹ Shenzhen Key Laboratory of Advanced Thin Films and Applications, College of Physics and Energy, Shenzhen University, Shenzhen 518060, China

² Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China

³ Institute of Thin Film Physics and Applications, College of Physics and Energy, Shenzhen University, Shenzhen 518060, China

^† These authors contributed equally to this work.

Materials 2018, 11(3), 355; https://doi.org/10.3390/ma11030355 - 28 Feb 2018

Cited by 39 | Viewed by 5945

Abstract

We provided a new method to improve the efficiency of Sb₂S₃ thin film solar cells. The TiO₂ electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb₂S₃ solar cells. [...] Read more.

We provided a new method to improve the efficiency of Sb₂S₃ thin film solar cells. The TiO₂ electron transport layers were doped by lithium to improve their charge extraction properties for the thermal-evaporated Sb₂S₃ solar cells. The Mott-Schottky curves suggested a change of energy band and faster charge transport in the Li-doped TiO₂ films. Compared with the undoped TiO₂, Li-doped mesoporous TiO₂ dramatically improved the photo-voltaic performance of the thermal-evaporated Sb₂S₃ thin film solar cells, with the average power conversion efficiency (PCE) increasing from 1.79% to 4.03%, as well as the improved open-voltage (V_oc), short-circuit current (J_sc) and fill factors. The best device based on Li-doped TiO₂ achieved a power conversion efficiency up to 4.42% as well as a V_oc of 0.645 V, which are the highest values among the reported thermal-evaporated Sb₂S₃ solar cells. This study showed that Li-doping on TiO₂ can effectively enhance the charge extraction properties of electron transport layers, offering a new strategy to improve the efficiency of Sb₂S₃-based solar cells. Full article

(This article belongs to the Section Energy Materials)

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17 pages, 21584 KiB

Open AccessArticle

Influence of Titanium Dioxide Nanoparticles on the Sulfate Attack upon Ordinary Portland Cement and Slag-Blended Mortars

by Atta-ur-Rehman, Abdul Qudoos, Hong Gi Kim and Jae-Suk Ryou^*

Department of Civil and Environmental Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea

Materials 2018, 11(3), 356; https://doi.org/10.3390/ma11030356 - 28 Feb 2018

Cited by 44 | Viewed by 7835

Abstract

In this study, the effects of titanium dioxide (TiO₂) nanoparticles on the sulfate attack resistance of ordinary Portland cement (OPC) and slag-blended mortars were investigated. OPC and slag-blended mortars (OPC:Slag = 50:50) were made with water to binder ratio of 0.4 [...] Read more.

In this study, the effects of titanium dioxide (TiO₂) nanoparticles on the sulfate attack resistance of ordinary Portland cement (OPC) and slag-blended mortars were investigated. OPC and slag-blended mortars (OPC:Slag = 50:50) were made with water to binder ratio of 0.4 and a binder to sand ratio of 1:3. TiO₂ was added as an admixture as 0%, 3%, 6%, 9% and 12% of the binder weight. Mortar specimens were exposed to an accelerated sulfate attack environment. Expansion, changes in mass and surface microhardness were measured. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC) tests were conducted. The formation of ettringite and gypsum crystals after the sulfate attack were detected. Both these products had caused crystallization pressure in the microstructure of mortars and deteriorated the mortars. Our results show that the addition of nano-TiO₂ accelerated expansion, variation in mass, loss of surface microhardness and widened cracks in OPC and slag-blended mortars. Nano-TiO₂ containing slag-blended mortars were more resistant to sulfate attack than nano-TiO₂ containing OPC mortars. Because nano-TiO₂ reduced the size of coarse pores, so it increased crystallization pressure due to the formation of ettringite and gypsum thus led to more damage under sulfate attack. Full article

(This article belongs to the Special Issue Application of Photoactive Nanomaterials in Degradation of Pollutants)

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23 pages, 12856 KiB

Open AccessArticle

Mapping the Galvanic Corrosion of Three Metals Coupled with a Wire Beam Electrode: The Influence of Temperature and Relative Geometrical Position

by Hong Ju^1,*

, Yuan-Feng Yang²

, Yun-Fei Liu¹, Shu-Fa Liu¹, Jin-Zhuo Duan¹ and Yan Li¹

¹ College of Mechanical and Electronic Engineering, China University of Petroleum, Qingdao 266580, China

² Corrosion and Protection Centre, The University of Manchester, Manchester M13 9PL, UK

Materials 2018, 11(3), 357; https://doi.org/10.3390/ma11030357 - 28 Feb 2018

Cited by 8 | Viewed by 4913

Abstract

The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at [...] Read more.

The local electrochemical properties of galvanic corrosion for three coupled metals in a desalination plant were investigated with three wire-beam electrodes as wire sensors: aluminum brass (HAl77-2), titanium (TA2), and 316L stainless steel (316L SS). These electrodes were used with artificial seawater at different temperatures. The potential and current–density distributions of the three-metal coupled system are inhomogeneous. The HAl77-2 wire anodes were corroded in the three-metal coupled system. The TA2 wires acted as cathodes and were protected; the 316L SS wires acted as secondary cathodes. The temperature and electrode arrangement have important effects on the galvanic corrosion of the three-metal coupled system. The corrosion current of the HAl77-2 increased with temperature indicating enhanced anode corrosion at higher temperature. In addition, the corrosion of HAl77-2 was more significant when the HAl77-2 wires were located in the middle of the coupled system than with the other two metal arrangement styles. Full article

(This article belongs to the Section Advanced Materials Characterization)

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15 pages, 6073 KiB

Open AccessArticle

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

by Jose Mario Paiva^1,2,*

, German Fox-Rabinovich¹, Edinei Locks Junior¹, Pietro Stolf¹, Yassmin Seid Ahmed¹

, Marcelo Matos Martins², Carlos Bork^1,3

and Stephen Veldhuis¹

¹ McMaster Manufacturing Research Institute (MMRI), Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S4L7, Canada

² Department of Mechanical and Materials Science, Catholic University of Santa Catarina, Rua Visconde de Taunay, 427-Centro, Joinville, SC 89203-005, Brazil

³ IFSul—Federal Institute Sul-rio-grandense—Campus Sapucaia do Sul, Av Copacabana, 100, Sapucaia do Sul, RS 93216-120, Brazil

Materials 2018, 11(3), 358; https://doi.org/10.3390/ma11030358 - 28 Feb 2018

Cited by 46 | Viewed by 7382

Abstract

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act [...] Read more.

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds. Full article

(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)

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13 pages, 4178 KiB

Open AccessArticle

Synthesis and Performance of Iron Oxide-Coated Ceramsite in a Biotrickling Filter for Nitric Oxide Removal under Thermophilic Conditions

by Han Li^1,2, Ze Guo³, Dafu Wu^1,*, Jing Fan², Shaobin Huang⁴ and Shaofeng Zhou⁴

¹ Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang 453003, China

² School of Environment, Henan Normal University, Xinxiang 453007, China

³ Department of Human Resources, Henan Institute of Technology, Xinxiang 453003, China

⁴ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China

Materials 2018, 11(3), 359; https://doi.org/10.3390/ma11030359 - 28 Feb 2018

Cited by 7 | Viewed by 3802

Abstract

A novel medium consisting of iron oxide-coated porous ceramsite (modified ceramsite) was investigated for NO removal under thermophilic conditions in this study. We used a surface coating method with FeCl₃·6H₂O as the modifier. When ceramsite was calcined for 4 [...] Read more.

A novel medium consisting of iron oxide-coated porous ceramsite (modified ceramsite) was investigated for NO removal under thermophilic conditions in this study. We used a surface coating method with FeCl₃·6H₂O as the modifier. When ceramsite was calcined for 4 h at 500 °C, the surface pH value decreased to 3.46, which is much lower than the isoelectric point of ceramsite, ensuring its surface was electropositive. The surface of modified ceramsite changed from two- to three-dimensional and exhibited excellent adsorption behavior to assist microbial growth; the maximum dry weight of the biofilm was 1.28 mg/g. It only took 8 days for the biofilter constructed from the modified ceramsite to start up, whereas that packed with commercial ceramsite took 22 days. The NO removal efficiency of the biofilter did not decrease apparently at high NO inlet concentration of above 1600 mg/m³ and maintained an average value of above 90% during the whole operation period. Additionally, the morphological observation showed that the loss of the surface coating was not obvious, and the coating properties remained stable during long-term operation. The maximum NO inlet loading of the biotrickling filter was 80 g/(m³·h) with an average removal efficiency of 91.1% along with a quick start-up when using the modified ceramsite filler. Thus, modified ceramsite can be considered a very effective medium in biotrickling filters for NO removal. Full article

(This article belongs to the Section Porous Materials)

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18 pages, 2218 KiB

Open AccessArticle

Rough Titanium Oxide Coating Prepared by Micro-Arc Oxidation Causes Down-Regulation of hTERT Expression, Molecular Presentation, and Cytokine Secretion in Tumor Jurkat T Cells

by Igor Khlusov^1,2,*

, Larisa Litvinova^2,*

, Valeria Shupletsova², Olga Khaziakhmatova², Elena Melashchenko², Kristina Yurova², Vladimir Leitsin²

, Marina Khlusova³, Vladimir Pichugin¹ and Yurii Sharkeev^1,4

¹ Department of Experimental Physics, National Research Tomsk Polytechnic University, Tomsk 634050, Russia

² Laboratory of Immunology and Cell Biotechnology, Immanuel Kant Baltic Federal University, Kaliningrad 236029, Russia

³ Department of Pathophysiology, Siberian State Medical University, Tomsk 634050, Russia

⁴ Institute of Strength Physics and Materials Science of SB RAS, Tomsk 634055, Russia

Materials 2018, 11(3), 360; https://doi.org/10.3390/ma11030360 - 28 Feb 2018

Cited by 10 | Viewed by 4237

Abstract

The response of the human Jurkat T cell leukemia-derived cell line (Jurkat T cells) after 24 h of in vitro exposure to a titanium substrate (12 × 12 × 1 mm³) with a bilateral rough (R_a = 2.2–3.7 μm) [...] Read more.

The response of the human Jurkat T cell leukemia-derived cell line (Jurkat T cells) after 24 h of in vitro exposure to a titanium substrate (12 × 12 × 1 mm³) with a bilateral rough (R_a = 2.2–3.7 μm) titanium oxide coating (rTOC) applied using the micro-arc method in a 20% orthophosphoric acid solution was studied. A 1.5-fold down-regulation of hTERT mRNA expression and decreases in CD3, CD4, CD8, and CD95 presentation and IL-4 and TNFα secretion were observed. Jurkat T cell inactivation was not correlated with the generation of intracellular reactive oxygen species (ROS) and was not mediated by TiO₂ nanoparticles with a diameter of 14 ± 8 nm at doses of 1 mg/L or 10 mg/L. The inhibitory effect of the rTOC (R_a = 2.2–3.7 μm) on the survival of Jurkat T cells (Spearman’s coefficient r_s = −0.95; n = 9; p < 0.0001) was demonstrated by an increase in the necrotic cell count among the cell population. In turn, an elevation of the Ra index of the rTOC was accompanied by a linear increase (r = 0.6; p < 0.000001, n = 60) in the magnitude of the negative electrostatic potential of the titanium oxide surface. Thus, the roughness of the rTOC induces an electrostatic potential and decreases the viability of the immortalized Jurkat T cells through mechanisms unrelated to ROS generation. This may be useful for replacement surgery applications of rough TiO₂ implants in cancer patients. Full article

(This article belongs to the Special Issue Metals Functionalization via Plasma Electrolytic Oxidation)

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16 pages, 2761 KiB

Open AccessArticle

Comparative Study of Ferroelectric and Piezoelectric Properties of BNT-BKT-BT Ceramics near the Phase Transition Zone

by David Andres Fernandez-Benavides, Aixa Ibeth Gutierrez-Perez, Angelica Maria Benitez-Castro, Maria Teresa Ayala-Ayala, Barbara Moreno-Murguia and Juan Muñoz-Saldaña^*

Centro de Investigación y de Estudios Avanzados del IPN, Lib. Norponiente No. 2000, Fracc. Real de Juriquilla 76230, Querétaro, Qro. Mexico

Materials 2018, 11(3), 361; https://doi.org/10.3390/ma11030361 - 1 Mar 2018

Cited by 62 | Viewed by 7051

Abstract

We report a comprehensive comparative study of ferroelectric and piezoelectric properties of BNT-BKT-BT ceramics through the MPB (morphotropic phase boundary) zone, from the rhombohedral to the tetragonal phases in the system (97.5−x)(Bi_0.5Na_0.5)TiO₃ + x(Bi_0.5 [...] Read more.

We report a comprehensive comparative study of ferroelectric and piezoelectric properties of BNT-BKT-BT ceramics through the MPB (morphotropic phase boundary) zone, from the rhombohedral to the tetragonal phases in the system (97.5−x)(Bi_0.5Na_0.5)TiO₃ + x(Bi_0.5K_0.5)TiO₃ + 2.5(BaTiO₃), where x = 0 to 24.5 mol %. The structural transitions were studied by XRD patterns and Raman spectra. The MPB was confirmed between x = 10 and 12.5 mol % BKT. The dielectric/ferroelectric/piezoelectric properties of the BNT-BKT-BT system are maximized in the MPB region exhibiting a dielectric constant of 1506, a remanent polarization of 34.4 μC/cm², a coercive field = 36.9 kV/cm, and piezoelectric values of d₃₃ = 109 pC/N, k_t = 0.52, and k_p = 0.24. Changes in microstructure as a function of BKT content are also presented and discussed. Full article

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23 pages, 9289 KiB

Open AccessArticle

Novel Precursor-Derived Meso-/Macroporous TiO₂/SiOC Nanocomposites with Highly Stable Anatase Nanophase Providing Visible Light Photocatalytic Activity and Superior Adsorption of Organic Dyes

by Eranezhuth Wasan Awin¹, Abhijeet Lale², Kollamala Chellappan Nair Hari Kumar¹, Umit Bilge Demirci³

, Samuel Bernard²

and Ravi Kumar^1,*

¹ Laboratory for High Performance Ceramics, Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras (IIT Madras), Chennai 600036, India

² Science des Procédés Céramiques et de Traitements de Surface (SPCTS), UMR CNRS 7315, Centre Européen de la Céramique, 12 rue Atlantis, 87068 Limoges CEDEX, France

³ IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM), Universite Montpellier, Place E. Bataillon, F-34095 Montpellier, France

Materials 2018, 11(3), 362; https://doi.org/10.3390/ma11030362 - 1 Mar 2018

Cited by 32 | Viewed by 6565

Abstract

Titania (TiO₂) is considered to have immense potential as a photocatalyst, the anatase phase in particular. There have been numerous attempts to push the limits of its catalytic activity to higher wavelengths to harness the visible electromagnetic radiation. Most of the [...] Read more.

Titania (TiO₂) is considered to have immense potential as a photocatalyst, the anatase phase in particular. There have been numerous attempts to push the limits of its catalytic activity to higher wavelengths to harness the visible electromagnetic radiation. Most of the investigations till date have been restricted to fine-tuning the bandgap by doping, control of defect chemistry at the surface and several to first principle simulations either with limited success or success at the cost of complexities in processing. Here, we report a simple and elegant way of preparing ceramics through precursor chemistry which involves synthesis of macroporous and mesoporous nanocomposites with in situ formation of TiO₂ nanocrystals into a robust and protecting SiOC matrix. The in situ nanoscaled TiO₂ is anatase of size 9–10 nm, which is uniformly distributed in an amorphous SiOC matrix forming a new generation of nanocomposites that combine the robustness, structural stability and durability of the SiOC matrix while achieving nanoscaled TiO₂ functionalities. The stabilization of the anatase phase even at temperature as high as 1200 °C was evident. With an average pore size of 6.8 nm, surface area of 129 m²/g (BET) and pore volume of 0.22 cm³/g (BET), mesoporosity was achieved in the nanocomposites. The composites exhibited visible light photocatalytic activity, which is attributed to the Ti–O–C/TiC bonds resulting in the reduction of band gap by 0.2 to 0.9 eV. Furthermore, the heterojunction formed between the amorphous SiOC and crystalline TiO₂ is also expected to minimize the recombination rate of electron-hole pair, making these novel nanocomposites based on TiO₂ extremely active in visible wavelength regime. Full article

(This article belongs to the Special Issue Polymer Derived Ceramics and Applications)

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14 pages, 5919 KiB

Open AccessArticle

Synthesis and Effect of Hierarchically Structured Ag-ZnO Hybrid on the Surface Antibacterial Activity of a Propylene-Based Elastomer Blends

by Pavel Bazant^*, Tomas Sedlacek

, Ivo Kuritka

, David Podlipny and Pavlina Holcapkova

Centre of Polymer Systems, Tomas Bata University in Zlin, Trida Tomase Bati 5678, 760 01 Zlin, Czech Republic

Materials 2018, 11(3), 363; https://doi.org/10.3390/ma11030363 - 1 Mar 2018

Cited by 23 | Viewed by 5073

Abstract

In this study, a hybrid Ag-ZnO nanostructured micro-filler was synthesized by the drop technique for used in plastic and medical industry. Furthermore, new antibacterial polymer nanocomposites comprising particles of Ag-ZnO up to 5 wt % and a blend of a thermoplastic polyolefin elastomer [...] Read more.

In this study, a hybrid Ag-ZnO nanostructured micro-filler was synthesized by the drop technique for used in plastic and medical industry. Furthermore, new antibacterial polymer nanocomposites comprising particles of Ag-ZnO up to 5 wt % and a blend of a thermoplastic polyolefin elastomer (TPO) with polypropylene were prepared using twin screw micro-compounder. The morphology and crystalline-phase structure of the hybrid Ag-ZnO nanostructured microparticles obtained was characterized by scanning electron microscopy and powder X-ray diffractometry. The specific surface area of this filler was investigated by means of nitrogen sorption via the Brunauer-Emmet-Teller method. A scanning electron microscope was used to conduct a morphological study of the polymer nanocomposites. Mechanical and electrical testing showed no adverse effects on the function of the polymer nanocomposites either due to the filler utilized or the given processing conditions, in comparison with the neat polymer matrix. The surface antibacterial activity of the compounded polymer nanocomposites was assessed against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538P, according to ISO 22196:2007 (E). All the materials at virtually every filler-loading level were seen to be efficient against both species of bacteria. Full article

(This article belongs to the Special Issue Multifunctional Oxide-Based Materials: From Synthesis to Application)

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17 pages, 4959 KiB

Open AccessArticle

Impact of Different Binders on the Roughness, Adhesion Strength, and Other Properties of Mortars with Expanded Cork

by Danuta Barnat-Hunek^1,*

, Marcin K. Widomski^2,*

, Małgorzata Szafraniec¹ and Grzegorz Łagód²

¹ Faculty of Civil Engineering and Architecture, Lublin University of Technology, Nadbystrzycka St. 40, 20-618 Lublin, Poland

² Faculty of Environmental Engineering, Lublin University of Technology, Nadbystrzycka St. 40B, 20-618 Lublin, Poland

Materials 2018, 11(3), 364; https://doi.org/10.3390/ma11030364 - 1 Mar 2018

Cited by 38 | Viewed by 5339

Abstract

The aim of the research that is presented in this paper was to evaluate the physical and mechanical properties of heat-insulating mortars with expanded cork aggregates and different binders. In this work, the measurements of surface roughness and adhesion strength, supported by determination [...] Read more.

The aim of the research that is presented in this paper was to evaluate the physical and mechanical properties of heat-insulating mortars with expanded cork aggregates and different binders. In this work, the measurements of surface roughness and adhesion strength, supported by determination of basic mechanical and physical parameters, such as density, bulk density, open porosity, total porosity, absorbability, thermal conductivity coefficient, compressive strength, flexural strength, and frost resistance of mortars containing expanded oak cork, were performed. The scanning electron microscope (SEM) investigations demonstrated the microstructure, contact zone, and distribution of pores in the heat-insulating mortars containing expanded cork. The results indicated that the addition of expanded cork and different binders in heat-insulating mortars triggers changes in their roughness and adhesion strength. The SEM research confirmed the very good adhesion of the paste to the cork aggregate. Full article

(This article belongs to the Special Issue Recycled Materials, Eco-design and 3D Printing)

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12 pages, 4755 KiB

Open AccessArticle

RGB-Stack Light Emitting Diode Modules with Transparent Glass Circuit Board and Oil Encapsulation

by Ying-Chang Li¹, Yuan-Hsiao Chang², Preetpal Singh², Liann-Be Chang^1,2,3,4,*, Der-Hwa Yeh², Ting-Yu Chao², Si-Yun Jian², Yu-Chi Li², Cher Ming Tan^2,4,5

, Chao-Sung Lai^2,4,6, Lee Chow⁷

and Shang-Ping Ying⁸

¹ Green Technology Research Center, Chang Gung University, Kweishan, Taoyuan 333, Taiwan

² Department of Electronic Engineering, Chang Gung University, Kweishan, Taoyuan 333, Taiwan

³ Department of Otolaryngology, Head and Neck Surgery, Chang Gung Memorial Hospital, Kweishan, Taoyuan 333, Taiwan

⁴ Department of Materials Engineering, Ming Chi University of Technology, Taishan, New Taipei City 243, Taiwan

⁵ Department of Urology, Chang Gung Memorial Hospital, Kweishan, Taoyuan 333, Taiwan

⁶ Department of Nephrology, Chang Gung Memorial Hospital, Kweishan, Taoyuan 333, Taiwan

⁷ Department of Physics, University of Central Florida, Orlando, FL 32816, USA

⁸ Department of Opto-Electronic System Engineering, Minghsin University of Science and Technology, Xinfeng Hsinchu 30401, Taiwan

Materials 2018, 11(3), 365; https://doi.org/10.3390/ma11030365 - 1 Mar 2018

Cited by 2 | Viewed by 6347

Abstract

The light emitting diode (LED) is widely used in modern solid-state lighting applications, and its output efficiency is closely related to the submounts’ material properties. Most submounts used today, such as low-power printed circuit boards (PCBs) or high-power metal core printed circuit boards [...] Read more.

The light emitting diode (LED) is widely used in modern solid-state lighting applications, and its output efficiency is closely related to the submounts’ material properties. Most submounts used today, such as low-power printed circuit boards (PCBs) or high-power metal core printed circuit boards (MCPCBs), are not transparent and seriously decrease the output light extraction. To meet the requirements of high light output and better color mixing, a three-dimensional (3-D) stacked flip-chip (FC) LED module is proposed and demonstrated. To realize light penetration and mixing, the mentioned 3-D vertically stacking RGB LEDs use transparent glass as FC package submounts called glass circuit boards (GCB). Light emitted from each GCB stacked LEDs passes through each other and thus exhibits good output efficiency and homogeneous light-mixing characteristics. In this work, the parasitic problem of heat accumulation, which caused by the poor thermal conductivity of GCB and leads to a serious decrease in output efficiency, is solved by a proposed transparent cooling oil encapsulation (OCP) method. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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11 pages, 3438 KiB

Open AccessArticle

Microstructures and Mechanical Properties of Commercially Pure Ti Processed by Rotationally Accelerated Shot Peening

by Zhaowen Huang, Yang Cao, Jinfeng Nie, Hao Zhou^* and Yusheng Li^*

Nano and Heterogeneous Structural Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

Materials 2018, 11(3), 366; https://doi.org/10.3390/ma11030366 - 2 Mar 2018

Cited by 21 | Viewed by 4557

Abstract

Gradient structured materials possess good combinations of strength and ductility, rendering the materials attractive in industrial applications. In this research, a surface nanocrystallization (SNC) technique, rotationally accelerated shot peening (RASP), was employed to produce a gradient nanostructured pure Ti with a deformation layer [...] Read more.

Gradient structured materials possess good combinations of strength and ductility, rendering the materials attractive in industrial applications. In this research, a surface nanocrystallization (SNC) technique, rotationally accelerated shot peening (RASP), was employed to produce a gradient nanostructured pure Ti with a deformation layer that had a thickness of 2000 μm, which is thicker than those processed by conventional SNC techniques. It is possible to fabricate a gradient structured Ti workpiece without delamination. Moreover, based on the microstructural features, the microstructure of the processed sample can be classified into three regions, from the center to the surface of the RASP-processed sample: (1) a twinning-dominated core region; (2) a “twin intersection”-dominated twin transition region; and (3) the nanostructured region, featuring nanograins. A microhardness gradient was detected from the RASP-processed Ti. The surface hardness was more than twice that of the annealed Ti sample. The RASP-processed Ti sample exhibited a good combination of yield strength and uniform elongation, which may be attributed to the high density of deformation twins and a strong back stress effect. Full article

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17 pages, 3272 KiB

Open AccessArticle

Highly-Bioreactive Silica-Based Mesoporous Bioactive Glasses Enriched with Gallium(III)

by Sandra Sanchez-Salcedo^1,2

, Gianluca Malavasi^3,*, Antonio J. Salinas^1,2,*

, Gigliola Lusvardi³, Luca Rigamonti³

, Ledi Menabue³ and Maria Vallet-Regi^1,2

¹ Dpto. Química en Ciencias Farmacéuticas, Instituto de Investigación Sanitaria Hospital 12 de Octubre, Universidad Complutense de Madrid, 28040 Madrid, Spain

² Centro Investigación Biomédica en Red Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 28040 Madrid, Spain

³ Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Via G. Campi 103, 41125 Modena, Italy

Materials 2018, 11(3), 367; https://doi.org/10.3390/ma11030367 - 2 Mar 2018

Cited by 33 | Viewed by 5414

Abstract

Beneficial effects in bone cell growth and antibacterial action are currently attributed to Ga³⁺ ions. Thus, they can be used to upgrade mesoporous bioactive glasses (MBGs), investigated for tissue engineering, whenever they released therapeutic amounts of gallium ions to the surrounding medium. [...] Read more.

Beneficial effects in bone cell growth and antibacterial action are currently attributed to Ga³⁺ ions. Thus, they can be used to upgrade mesoporous bioactive glasses (MBGs), investigated for tissue engineering, whenever they released therapeutic amounts of gallium ions to the surrounding medium. Three gallium-enriched MBGs with composition (in mol %) xSiO₂–yCaO–zP₂O₅–5Ga₂O₃, being x = 70, y = 15, z = 10 for Ga_1; x = 80, y = 12, z = 3 for Ga_2; and x = 80, y = 15, z = 0 for Ga_3, were investigated and compared with the gallium-free 80SiO₂–15CaO–5P₂O₅ MBG (B). ²⁹Si and ³¹P MAS NMR analyses indicated that Ga³⁺ acts as network modifier in the glass regions with higher polymerization degree and as network former in the zones with high concentration of classical modifiers (Ca²⁺ ions). Ga_1 and Ga_2 exhibited a quick in vitro bioactive response because they were coated by an apatite-like layer after 1 and 3 days in simulated body fluid. Although we have not conducted biological tests in this paper (cells or bacteria), Ga_1 released high but non-cytotoxic amounts of Ga³⁺ ions in Todd Hewitt Broth culture medium that were 140 times higher than the IC90 of Pseudomonas aeruginosa bacteria, demonstrating its potential for tissue engineering applications. Full article

(This article belongs to the Special Issue Selected papers from EUROMAT 2017 Conference—Biomaterials)

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6 pages, 2162 KiB

Open AccessArticle

Investigations on Structural, Optical and X-Radiation Responsive Properties of a-Se Thin Films Fabricated by Thermal Evaporation Method at Low Vacuum Degree

by Jitao Li¹, Xinghua Zhu^1,2, Dingyu Yang^1,*, Peng Gu¹ and Haihua Wu¹

¹ College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225, China

² College of Intelligent Manufacturing, Sichuan University of Arts and Science, Dazhou 635000, China

Materials 2018, 11(3), 368; https://doi.org/10.3390/ma11030368 - 2 Mar 2018

Cited by 8 | Viewed by 4506

Abstract

Amorphous selenium (a-Se) thin films with a thickness of 1200 nm were successfully fabricated by thermal evaporation at a low vacuum degree of 10⁻² Pa. The structural properties involving phase and morphology showed that a-Se thin films could be resistant to 60 [...] Read more.

Amorphous selenium (a-Se) thin films with a thickness of 1200 nm were successfully fabricated by thermal evaporation at a low vacuum degree of 10⁻² Pa. The structural properties involving phase and morphology showed that a-Se thin films could be resistant to 60 °C in air. Also, a transformation to polycrystalline Selenium (p-Se) was shown as the annealing temperature rose to 62 °C and 65 °C, with obvious changes in color and surface morphology. Moreover, as the a-Se transformed to p-Se, the samples’ transmittance decreased significantly, and the band gap declined dramatically from 2.15 eV to 1.92 eV. Finally, the X-radiation response of a-Se was investigated as an important property, revealing there is a remarkable response speed of photogeneration current both X-ray on and X-ray off, with a requirement of only a very small electrical field. Full article

(This article belongs to the Section Thin Films and Interfaces)

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13 pages, 4971 KiB

Open AccessArticle

Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining

by Cunao Feng¹

, Dekun Zhang^2,*, Kai Chen² and Yongbo Guo¹

¹ School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou 221116, China

² School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116, China

Materials 2018, 11(3), 369; https://doi.org/10.3390/ma11030369 - 2 Mar 2018

Cited by 4 | Viewed by 3387

Abstract

This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and [...] Read more.

This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions. The mixed-friction mechanism was in the period when the working conditions varied from high pressure and speed to low pressure and speed. Full article

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8 pages, 1225 KiB

Open AccessCommunication

Novel Wearable Electrodes Based on Conductive Chitosan Fabrics and Their Application in Smart Garments

by Haiming Qin¹, Junrong Li^1,*, Beihai He¹, Jingbo Sun², Lingrui Li² and Liying Qian^1,*

¹ State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China

² A Mu (Shenzhen) New Technology Co., Ltd., Shenzhen 518109, China

Materials 2018, 11(3), 370; https://doi.org/10.3390/ma11030370 - 2 Mar 2018

Cited by 43 | Viewed by 4538

Abstract

Smart garments, which can capture electrocardiogram signals at any time or location, can alert others to the risk of heart attacks and prevent sudden cardiac death when people are sleeping, walking, or running. Novel wearable electrodes for smart garments based on conductive chitosan [...] Read more.

Smart garments, which can capture electrocardiogram signals at any time or location, can alert others to the risk of heart attacks and prevent sudden cardiac death when people are sleeping, walking, or running. Novel wearable electrodes for smart garments based on conductive chitosan fabrics were fabricated by electroless plating of silver nanoparticles onto the surfaces of the fibers. The electrical resistance, which is related to the silver content of the composite fabrics, can be as low as 0.0332 ± 0.0041 Ω/sq due to the strong reactivity between amine groups and silver ions. After washing these fabrics eight times, the electrical resistance remained below 1 Ω/sq. The conductive chitosan fabrics were applied to smart garments as wearable electrodes to capture electrocardiogram signals of the human body in static state, jogging state, and running state, which showed good data acquisition ability and sensitivity. Full article

(This article belongs to the Section Advanced Composites)

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15 pages, 10611 KiB

Open AccessArticle

Regulating the Emission Spectrum of CsPbBr₃ from Green to Blue via Controlling the Temperature and Velocity of Microchannel Reactor

by Yong Tang¹, Hanguang Lu¹, Longshi Rao¹, Zongtao Li^1,*

, Xinrui Ding², Caiman Yan¹ and Binhai Yu¹

¹ Engineering Research Centre of Green Manufacturing for Energy-Saving and New Energy Technology, School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China

² Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA

Materials 2018, 11(3), 371; https://doi.org/10.3390/ma11030371 - 2 Mar 2018

Cited by 17 | Viewed by 6687

Abstract

The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs) is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr₃ QDs with tunable spectrum. By adjusting [...] Read more.

The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs) is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr₃ QDs with tunable spectrum. By adjusting the temperature and velocity of the microchannel reactor, the emission peaks of CsPbBr₃ QDs ranging from 520 nm to 430 nm were obtained, which is wider than that of QDs obtained in a traditional flask without changing halide component. The mechanism of photoluminescence (PL) spectral shift of CsPbBr₃ QDs was investigated, the result shows that the supersaturation control enabled by the superior mass and heat transfer performance in the microchannel is the key to achieve the wide range of PL spectrum, with only a change in the setting of the temperature controller required. The wide spectrum of CsPbBr₃ QDs can be applied to light-emitting diodes (LEDs), photoelectric sensors, lasers, etc. Full article

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17 pages, 4554 KiB

Open AccessArticle

Modification of Physico-Chemical Properties of Acryl-Coated Polypropylene Foils for Food Packaging by Reactive Particles from Oxygen Plasma

by Tomislava Vukušić¹, Alenka Vesel²

, Matej Holc³, Mario Ščetar¹

, Anet Režek Jambrak¹

and Miran Mozetič^2,*

¹ Department of Food Engineering, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia

² Department of Surface Engineering, Jozef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia

³ Jozef Stefan International Postgraduate School, Jamova cesta 39, 1000 Ljubljana, Slovenia

Materials 2018, 11(3), 372; https://doi.org/10.3390/ma11030372 - 3 Mar 2018

Cited by 18 | Viewed by 4632

Abstract

This investigation was focused on the influence of long-living neutral reactive oxygen species on the physico-chemical properties of acryl-coated polypropylene foils for food packaging. Reactive species were formed by passing molecular oxygen through a microwave discharge and leaking it to a processing chamber [...] Read more.

This investigation was focused on the influence of long-living neutral reactive oxygen species on the physico-chemical properties of acryl-coated polypropylene foils for food packaging. Reactive species were formed by passing molecular oxygen through a microwave discharge and leaking it to a processing chamber of a volume of 30 L, which was pumped by a rotary pump. The density of neutral O-atoms in the chamber was tuned by adjustment of both the effective pumping speed and the oxygen leak rate. The O-atom density was measured with a catalytic probe and was between 3 × 10¹⁸ and 5 × 10¹⁹ m⁻³. Commercial foils of biaxially oriented polypropylene (BOPP) coated with acrylic/ poly(vinylidene chloride) (AcPVDC) were mounted in the chamber and treated at room temperature by O atoms at various conditions, with the fluence between 1 × 10²¹ and 3 × 10²⁴ m⁻². The evolution of the surface wettability versus the fluence was determined by water contact angle (WCA) measurements, the formation of functional groups by X-ray photoelectron spectroscopy (XPS), and the morphology by atomic force microscopy (AFM). The WCA dropped from the initial 75° to approximately 40° after the fluence of a few 10²² m⁻² and remained unchanged thereafter, except for fluences above 10²⁴ m⁻², where the WCA dropped to approximately 30°. XPS and AFM results allowed for drawing correlations between the wettability, surface composition, and morphology. Full article

(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)

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15 pages, 5334 KiB

Open AccessArticle

The Influence of Salt Anions on Heavy Metal Ion Adsorption on the Example of Nickel

by Mandy Mende, Dana Schwarz, Christine Steinbach, Regine Boldt

and Simona Schwarz^*

Leibniz-Institut fuer Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden, Germany

Materials 2018, 11(3), 373; https://doi.org/10.3390/ma11030373 - 3 Mar 2018

Cited by 37 | Viewed by 5795

Abstract

The biodegradable polysaccharide chitosan possesses protonated and natural amino groups at medium pH values and has therefore been used as an adsorbing material for nickel salts in water treatment. Nickel is a problematic heavy metal ion which can cause various diseases and disorders [...] Read more.

The biodegradable polysaccharide chitosan possesses protonated and natural amino groups at medium pH values and has therefore been used as an adsorbing material for nickel salts in water treatment. Nickel is a problematic heavy metal ion which can cause various diseases and disorders in living organisms. Here, we show the influence of oxyanions (e.g., nitrate and sulfate) to the adsorption of nickel ions. Hence, simultaneously we are addressing the increasing global problem of nitrate and sulfate ion pollution in groundwater and surface water. A series of adsorption experiments was carried out in order to determine (i) the adsorption equilibrium, (ii) the adsorption capacity in dependence on the initial nickel ion concentration, and (iii) the influence of the anion presented in solution for the adsorption capacity. Surface morphology of chitosan flakes before and after the adsorption process has been studied with SEM-EDX analysis. The chitosan flakes exhibited promising adsorption capacities of 81.9 mg·g⁻¹ and 21.2 mg·g⁻¹ for nickel (sulfate) and nickel (nitrate), respectively. The calculated values of Gibbs free energy change ΔG⁰ confirm the higher adsorption of nickel ions in presence of sulfate ions. Hence, higher anion valence leads to a higher adsorption capacity. Full article

(This article belongs to the Section Biomaterials)

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17 pages, 22396 KiB

Open AccessArticle

Mechanical Properties of Optimized Diamond Lattice Structure for Bone Scaffolds Fabricated via Selective Laser Melting

by Fei Liu¹

, David Z. Zhang^1,2,*, Peng Zhang¹, Miao Zhao¹ and Salman Jafar¹

¹ State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China

² College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF, UK

Materials 2018, 11(3), 374; https://doi.org/10.3390/ma11030374 - 3 Mar 2018

Cited by 153 | Viewed by 11681

Abstract

Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties [...] Read more.

Developments in selective laser melting (SLM) have enabled the fabrication of periodic cellular lattice structures characterized by suitable properties matching the bone tissue well and by fluid permeability from interconnected structures. These multifunctional performances are significantly affected by cell topology and constitutive properties of applied materials. In this respect, a diamond unit cell was designed in particular volume fractions corresponding to the host bone tissue and optimized with a smooth surface at nodes leading to fewer stress concentrations. There were 33 porous titanium samples with different volume fractions, from 1.28 to 18.6%, manufactured using SLM. All of them were performed under compressive load to determine the deformation and failure mechanisms, accompanied by an in-situ approach using digital image correlation (DIC) to reveal stress–strain evolution. The results showed that lattice structures manufactured by SLM exhibited comparable properties to those of trabecular bone, avoiding the effects of stress-shielding and increasing longevity of implants. The curvature of optimized surface can play a role in regulating the relationship between density and mechanical properties. Owing to the release of stress concentration from optimized surface, the failure mechanism of porous titanium has been changed from the pattern of bottom-up collapse by layer (or cell row) to that of the diagonal (45°) shear band, resulting in the significant enhancement of the structural strength. Full article

(This article belongs to the Section Porous Materials)

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27 pages, 18046 KiB

Open AccessArticle

Design and 4D Printing of Cross-Folded Origami Structures: A Preliminary Investigation

by Joanne Ee Mei Teoh^*, Jia An

, Xiaofan Feng, Yue Zhao, Chee Kai Chua

and Yong Liu

Singapore Centre for 3D Printing, School of Mechanical & Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore

Materials 2018, 11(3), 376; https://doi.org/10.3390/ma11030376 - 3 Mar 2018

Cited by 49 | Viewed by 7890

Abstract

In 4D printing research, different types of complex structure folding and unfolding have been investigated. However, research on cross-folding of origami structures (defined as a folding structure with at least two overlapping folds) has not been reported. This research focuses on the investigation [...] Read more.

In 4D printing research, different types of complex structure folding and unfolding have been investigated. However, research on cross-folding of origami structures (defined as a folding structure with at least two overlapping folds) has not been reported. This research focuses on the investigation of cross-folding structures using multi-material components along different axes and different horizontal hinge thickness with single homogeneous material. Tensile tests were conducted to determine the impact of multi-material components and horizontal hinge thickness. In the case of multi-material structures, the hybrid material composition has a significant impact on the overall maximum strain and Young’s modulus properties. In the case of single material structures, the shape recovery speed is inversely proportional to the horizontal hinge thickness, while the flexural or bending strength is proportional to the horizontal hinge thickness. A hinge with a thickness of 0.5 mm could be folded three times prior to fracture whilst a hinge with a thickness of 0.3 mm could be folded only once prior to fracture. A hinge with a thickness of 0.1 mm could not even be folded without cracking. The introduction of a physical hole in the center of the folding/unfolding line provided stress relief and prevented fracture. A complex flower petal shape was used to successfully demonstrate the implementation of overlapping and non-overlapping folding lines using both single material segments and multi-material segments. Design guidelines for establishing cross-folding structures using multi-material components along different axes and different horizontal hinge thicknesses with single or homogeneous material were established. These guidelines can be used to design and implement complex origami structures with overlapping and non-overlapping folding lines. Combined overlapping folding structures could be implemented and allocating specific hole locations in the overall designs could be further explored. In addition, creating a more precise prediction by investigating sets of in between hinge thicknesses and comparing the folding times before fracture, will be the subject of future work. Full article

(This article belongs to the Special Issue NextGen Materials for 3D Printing)

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10 pages, 2175 KiB

Open AccessArticle

Enhancement of Inverted Polymer Solar Cells Performances Using Cetyltrimethylammonium-Bromide Modified ZnO

by Chung-Kai Wu^1,†, Kundan Sivashanmugan^1,†, Tzung-Fang Guo² and Ten-Chin Wen^1,*

¹ Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan

² Department of Photonics, National Cheng Kung University, Tainan 70101, Taiwan

^† These authors contributed equally to this study.

Materials 2018, 11(3), 378; https://doi.org/10.3390/ma11030378 - 4 Mar 2018

Cited by 19 | Viewed by 5741

Abstract

In this study, the performance and stability of inverted bulk heterojunction (BHJ) polymer solar cells (PSCs) is enhanced by doping zinc oxide (ZnO) with 0–6 wt % cetyltrimethylammonium bromide (CTAB) in the sol-gel ZnO precursor solution. The power conversion efficiency (PCE) of the [...] Read more.

In this study, the performance and stability of inverted bulk heterojunction (BHJ) polymer solar cells (PSCs) is enhanced by doping zinc oxide (ZnO) with 0–6 wt % cetyltrimethylammonium bromide (CTAB) in the sol-gel ZnO precursor solution. The power conversion efficiency (PCE) of the optimized 3 wt % CTAB-doped ZnO PSCs was increased by 9.07%, compared to a PCE of 7.31% for the pristine ZnO device. The 0–6 wt % CTAB-doped ZnO surface roughness was reduced from 2.6 to 1 nm and the number of surface defects decreased. The X-ray photoelectron spectroscopy binding energies of Zn 2p^3/2 (1021.92 eV) and 2p^1/2 (1044.99 eV) shifted to 1022.83 and 1045.88 eV, respectively, which is related to strong chemical bonding via bromide ions (Br⁻) that occupy oxygen vacancies in the ZnO lattice, improving the PCE of PSCs. The concentration of CTAB in ZnO significantly affected the work function of PSC devices; however, excessive CTAB increased the work function of the ZnO layer, resulting from the aggregation of CTAB molecules. In addition, after a 120-hour stability test in the atmosphere with 40% relative humidity, the inverted device based on CTAB-doped ZnO retained 92% of its original PCE and that based on pristine ZnO retained 68% of its original PCE. The obtained results demonstrate that the addition of CTAB into ZnO can dramatically influence the optical, electrical, and morphological properties of ZnO, enhancing the performance and stability of BHJ PSCs. Full article

(This article belongs to the Section Energy Materials)

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12 pages, 9104 KiB

Open AccessArticle

Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

by Guowei Li, Furong Chen^*, Yongquan Han and Yahong Liang

School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China

Materials 2018, 11(3), 379; https://doi.org/10.3390/ma11030379 - 5 Mar 2018

Cited by 12 | Viewed by 4283

Abstract

In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA) welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT). [...] Read more.

In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA) welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT). The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η′ phase. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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12 pages, 4762 KiB

Open AccessArticle

Multi-Scale Modeling for Predicting the Stiffness and Strength of Hollow-Structured Metal Foams with Structural Hierarchy

by Yong Yi^1,*,†

, Xiaoyang Zheng^1,2,†

, Zhibing Fu², Chaoyang Wang^2,*, Xibin Xu² and Xiulan Tan²

¹ School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010, China

² Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900, China

^† These authors contributed equally to this work.

Materials 2018, 11(3), 380; https://doi.org/10.3390/ma11030380 - 5 Mar 2018

Cited by 11 | Viewed by 4462

Abstract

This work was inspired by previous experiments which managed to establish an optimal template-dealloying route to prepare ultralow density metal foams. In this study, we propose a new analytical–numerical model of hollow-structured metal foams with structural hierarchy to predict its stiffness and strength. [...] Read more.

This work was inspired by previous experiments which managed to establish an optimal template-dealloying route to prepare ultralow density metal foams. In this study, we propose a new analytical–numerical model of hollow-structured metal foams with structural hierarchy to predict its stiffness and strength. The two-level model comprises a main backbone and a secondary nanoporous structure. The main backbone is composed of hollow sphere-packing architecture, while the secondary one is constructed of a bicontinuous nanoporous network proposed to describe the nanoscale interactions in the shell. Firstly, two nanoporous models with different geometries are generated by Voronoi tessellation, then the scaling laws of the mechanical properties are determined as a function of relative density by finite volume simulation. Furthermore, the scaling laws are applied to identify the uniaxial compression behavior of metal foams. It is shown that the thickness and relative density highly influence the Young’s modulus and yield strength, and vacancy defect determines the foams being self-supported. The present study provides not only new insights into the mechanical behaviors of both nanoporous metals and metal foams, but also a practical guide for their fabrication and application. Full article

(This article belongs to the Section Porous Materials)

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18 pages, 7008 KiB

Open AccessArticle

Recyclable Aggregates of Mesoporous Titania Synthesized by Thermal Treatment of Amorphous or Peptized Precursors

by Maria Cristina Mascolo^1,*

and Terry Arthur Ring²

¹ Laboratory of Materials, Department of Civil and Mechanical Engineering, University of Cassino and Southern Latium, G. Di Biasio 43 Street, 03043 Cassino (FR), Italy

² Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84112, USA

Materials 2018, 11(3), 381; https://doi.org/10.3390/ma11030381 - 5 Mar 2018

Cited by 4 | Viewed by 3232

Abstract

Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC₂H₅)₄ or of Ti(OC₂H₅ [...] Read more.

Recyclable aggregates of mesoporous titania with different anatase–rutile ratios have been prepared by thermal treatments of either amorphous or peptized precursors. These last two have been obtained by hydrolysis of either Ti(OC₂H₅)₄ or of Ti(OC₂H₅)₄ in mixture with 5 mol % Zr(OC₃H₇)₄ at room temperature in the presence of NH₄OH as a catalyzing agent. The anatase–rutile ratio, the recyclable aggregates of the nano-sized particles, the mesoporosity, the surface area and the crystallinity of the resulting crystallized products of titania can be controlled by the synthesis parameters including: concentration of ammonia catalyst, stirring time and concentration of the peptizing HNO₃, drying method of peptized precursors, calcination temperature, and finally the ramp rate up to the titania crystallization temperature. A broad range of synthesis parameters control the crystal sizes of titania particles produced. This allows catalyst preparation with very different crystal size, surface area, anatase to rutile crystal ratio and various mesoporous structures. Drying by lyophilization of precursors reduce the aggregation of the primary particles giving micro-/macroporous structures. Full article

(This article belongs to the Section Porous Materials)

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14 pages, 2381 KiB

Open AccessArticle

Sonication-Induced Modification of Carbon Nanotubes: Effect on the Rheological and Thermo-Oxidative Behaviour of Polymer-Based Nanocomposites

by Rossella Arrigo^1,2,*

, Rosalia Teresi¹, Cristian Gambarotti³, Filippo Parisi⁴

, Giuseppe Lazzara⁴

and Nadka Tzankova Dintcheva¹

¹ Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali, Università degli Studi di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo, Italy

² Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Viale T. Michel, 5, 15121 Alessandria, Italy

³ Dipartimento di Chimica, Materiali ed Ingegneria Chimica “G. Natta”, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy

⁴ Dipartimento di Fisica e Chimica, Università degli Studi di Palermo, Viale delle Scienze, Ed. 17, 90128 Palermo, Italy

Materials 2018, 11(3), 383; https://doi.org/10.3390/ma11030383 - 5 Mar 2018

Cited by 82 | Viewed by 5235

Abstract

The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high [...] Read more.

The aim of this work is the investigation of the effect of ultrasound treatment on the structural characteristics of carbon nanotubes (CNTs) and the consequent influence that the shortening induced by sonication exerts on the morphology, rheological behaviour and thermo-oxidative resistance of ultra-high molecular weight polyethylene (UHMWPE)-based nanocomposites. First, CNTs have been subjected to sonication for different time intervals and the performed spectroscopic and morphological analyses reveal that a dramatic decrease of the CNT’s original length occurs with increased sonication time. The reduction of the initial length of CNTs strongly affects the nanocomposite rheological behaviour, which progressively changes from solid-like to liquid-like as the CNT sonication time increases. The study of the thermo-oxidative behaviour of the investigated nanocomposites reveals that the CNT sonication has a detrimental effect on the thermo-oxidative stability of nanocomposites, especially for long exposure times. The worsening of the thermo-oxidative resistance of sonicated CNT-containing nanocomposites could be attributed to the lower thermal conductivity of low-aspect-ratio CNTs, which causes the increase of the local temperature at the polymer/nanofillers interphase, with the consequent acceleration of the degradative phenomena. Full article

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13 pages, 1616 KiB

Open AccessFeature PaperArticle

Production of Low Cost Carbon-Fiber through Energy Optimization of Stabilization Process

by Gelayol Golkarnarenji¹, Minoo Naebe², Khashayar Badii³, Abbas S. Milani⁴, Reza N. Jazar¹ and Hamid Khayyam^1,*

¹ School of Engineering, RMIT University, Melbourne, VIC 3001, Australia

² Institute for Frontier Materials, Carbon Nexus, Deakin University, Waurn Ponds, VIC 3216, Australia

³ School of Engineering, Deakin University, Waurn Ponds, VIC 3216, Australia

⁴ Materials and Manufacturing Research Institute, University of British Columbia, Kelowna, BC V1V 1V7, Canada

Materials 2018, 11(3), 385; https://doi.org/10.3390/ma11030385 - 5 Mar 2018

Cited by 32 | Viewed by 5658

Abstract

To produce high quality and low cost carbon fiber-based composites, the optimization of the production process of carbon fiber and its properties is one of the main keys. The stabilization process is the most important step in carbon fiber production that consumes a [...] Read more.

To produce high quality and low cost carbon fiber-based composites, the optimization of the production process of carbon fiber and its properties is one of the main keys. The stabilization process is the most important step in carbon fiber production that consumes a large amount of energy and its optimization can reduce the cost to a large extent. In this study, two intelligent optimization techniques, namely Support Vector Regression (SVR) and Artificial Neural Network (ANN), were studied and compared, with a limited dataset obtained to predict physical property (density) of oxidative stabilized PAN fiber (OPF) in the second zone of a stabilization oven within a carbon fiber production line. The results were then used to optimize the energy consumption in the process. The case study can be beneficial to chemical industries involving carbon fiber manufacturing, for assessing and optimizing different stabilization process conditions at large. Full article

(This article belongs to the Special Issue Modeling and Simulation of Advanced Composite Materials)

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9 pages, 3592 KiB

Open AccessArticle

Effect of Growth Temperature on the Structural and Electrical Properties of ZrO₂ Films Fabricated by Atomic Layer Deposition Using a CpZr[N(CH₃)₂]₃/C₇H₈ Cocktail Precursor

by Jong-Ki An^1,2,†

, Nak-Kwan Chung^2,†, Jin-Tae Kim^2,3, Sung-Ho Hahm¹, Geunsu Lee⁴, Sung Bo Lee⁵

, Taehoon Lee⁶, In-Sung Park^6,7,* and Ju-Young Yun^2,3,*

¹ School of Electronics Engineering, Kyungpook National University, Daegu 41566, Korea

² Materials and Energy Measurement Center, Korea Research Institute of Standards and Science (KRISS), Daejeon 34113, Korea

³ Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 34113, Korea

⁴ Eugene Technology Materials, Gyeonggi-do 16675, Korea

⁵ Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Korea

⁶ Division of Materials Science and Engineering, Hanyang University, Seoul 04763, Korea

⁷ Institute of Nano Science and Technology, Hanyang University, Seoul 04763, Korea

^† These authors contributed equally to this study.

Materials 2018, 11(3), 386; https://doi.org/10.3390/ma11030386 - 5 Mar 2018

Cited by 20 | Viewed by 5225

Abstract

The effect of growth temperature on the atomic layer deposition of zirconium oxide (ZrO₂) dielectric thin films that were fabricated using a CpZr[N(CH₃)₂]₃/C₇H₈ cocktail precursor with ozone was investigated. The chemical, structural, [...] Read more.

The effect of growth temperature on the atomic layer deposition of zirconium oxide (ZrO₂) dielectric thin films that were fabricated using a CpZr[N(CH₃)₂]₃/C₇H₈ cocktail precursor with ozone was investigated. The chemical, structural, and electrical properties of ZrO₂ films grown at temperatures from 250 to 350 °C were characterized. Stoichiometric ZrO₂ films formed at 250–350 °C with an atomic ratio of O to Zr of 1.8–1.9 and a low content of carbon impurities. The film formed at 300 °C was predominantly the tetragonal crystalline phase, whereas that formed at 350 °C was a mixture of tetragonal and monoclinic phases. Electrical properties, such as capacitance, leakage current, and voltage linearity of TiN/ZrO₂/TiN capacitors fabricated using the thin ZrO₂ films grown at different temperatures were compared capacitor applications. The ZrO₂ film grown at 300 °C exhibited low impurity content, predominantly tetragonal crystalline structure, a high dielectric permittivity of 38.3, a low leakage current of below 10⁻⁷ A/cm² at 2 V, and low-voltage linearity. Full article

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7 pages, 2684 KiB

Open AccessArticle

Green Synthesis of Boron Carbonitride with High Capacitance

by Dongping Chen, Yanzhen Huang, Xinling Hu, Rongkai Li, Yingjiang Qian and Dongxu Li^*

College of Materials Science and Engineering, Huaqiao University, Xiamen 361021, China

Materials 2018, 11(3), 387; https://doi.org/10.3390/ma11030387 - 6 Mar 2018

Cited by 19 | Viewed by 9703

Abstract

Boron carbonitrides (BCN) have attracted great interest in superhard or energy storage materials. In this work, thin BCN sheets were synthesized at 250 °C by a facile and green solvothermal method. The structure and morphology were characterized by X-ray diffraction (XRD), Raman spectroscopy, [...] Read more.

Boron carbonitrides (BCN) have attracted great interest in superhard or energy storage materials. In this work, thin BCN sheets were synthesized at 250 °C by a facile and green solvothermal method. The structure and morphology were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the results of electrochemical experiments, the thin BCN sheet exhibited excellent capacitance performance (343.1 F/g at a current density of 0.5 A/g) and cycling stability (90%), which showed high potential applications in supercapacitors. Full article

(This article belongs to the Special Issue Next Generation of Supercapacitors: New Materials and Novel Devices)

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16 pages, 3590 KiB

Open AccessArticle

An Optical Biosensing Strategy Based on Selective Light Absorption and Wavelength Filtering from Chromogenic Reaction

by Hyeong Jin Chun¹, Yong Duk Han¹, Yoo Min Park^1,2, Ka Ram Kim¹, Seok Jae Lee² and Hyun C. Yoon^1,*

¹ Department of Molecular Science and Technology, Ajou University, Suwon 16499, Korea

² Nano-bio Application Team, National NanoFab Center (NNFC), Daejeon 34141, Korea

Materials 2018, 11(3), 388; https://doi.org/10.3390/ma11030388 - 6 Mar 2018

Cited by 13 | Viewed by 4846

Abstract

To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate [...] Read more.

To overcome the time and space constraints in disease diagnosis via the biosensing approach, we developed a new signal-transducing strategy that can be applied to colorimetric optical biosensors. Our study is focused on implementation of a signal transduction technology that can directly translate the color intensity signals—that require complicated optical equipment for the analysis—into signals that can be easily counted with the naked eye. Based on the selective light absorption and wavelength-filtering principles, our new optical signaling transducer was built from a common computer monitor and a smartphone. In this signal transducer, the liquid crystal display (LCD) panel of the computer monitor served as a light source and a signal guide generator. In addition, the smartphone was used as an optical receiver and signal display. As a biorecognition layer, a transparent and soft material-based biosensing channel was employed generating blue output via a target-specific bienzymatic chromogenic reaction. Using graphics editor software, we displayed the optical signal guide patterns containing multiple polygons (a triangle, circle, pentagon, heptagon, and 3/4 circle, each associated with a specified color ratio) on the LCD monitor panel. During observation of signal guide patterns displayed on the LCD monitor panel using a smartphone camera via the target analyte-loaded biosensing channel as a color-filtering layer, the number of observed polygons changed according to the concentration of the target analyte via the spectral correlation between absorbance changes in a solution of the biosensing channel and color emission properties of each type of polygon. By simple counting of the changes in the number of polygons registered by the smartphone camera, we could efficiently measure the concentration of a target analyte in a sample without complicated and expensive optical instruments. In a demonstration test on glucose as a model analyte, we could easily measure the concentration of glucose in the range from 0 to 10 mM. Full article

(This article belongs to the Special Issue Soft Material-Enabled Electronics for Medicine, Healthcare, and Human-Machine Interfaces)

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12 pages, 8717 KiB

Open AccessArticle

The Microstructure Evolution of a Fe₃Al Alloy during the LENS Process

by Krzysztof Karczewski

, Tomasz Durejko

and Tomasz Czujko^*

Department of Advanced Materials and Technologies, Military University of Technology, ul. Gen. Urbanowicza 2, 00-908 Warsaw, Poland

Materials 2018, 11(3), 390; https://doi.org/10.3390/ma11030390 - 7 Mar 2018

Cited by 9 | Viewed by 3720

Abstract

A Fe₃Al intermetallic alloy has been successfully prepared by the laser-engineered net shaping (LENS) process. The applied process parameters were selected to provide various cooling rates during the solidification of the laser-melted material. The macro- and microstructure and the micro- and [...] Read more.

A Fe₃Al intermetallic alloy has been successfully prepared by the laser-engineered net shaping (LENS) process. The applied process parameters were selected to provide various cooling rates during the solidification of the laser-melted material. The macro- and microstructure and the micro- and macrotexture of Fe₃Al samples were investigated. The influence of the cooling rate on grain morphology and texture is discussed. For the applied cooling rate range of 0.64 × 10⁴ K/s–2.6 × 10⁴ K/s, the structure is characterized by the presence of columnar grains for which the growth is directed upwards from the substrate. The intensity of the microtexture varies with the height of the sample and the cooling rate. The intensity of the texture increases with the decrease in the cooling rate. The samples that were obtained with low and medium cooling rates are characterized by the well-developed <100> and <111> macrotextures. The Fe₃Al alloy that was produced with a high cooling rate did not show a specific texture, which is reflected in the fairly uniform distribution of the normalized density intensity. Only a very weak texture with a <100> type component was observed. Full article

(This article belongs to the Special Issue Laser Materials Processing)

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15 pages, 4366 KiB

Open AccessFeature PaperArticle

Surface Treatment of PEOT/PBT (55/45) with a Dielectric Barrier Discharge in Air, Helium, Argon and Nitrogen at Medium Pressure

by Pieter Cools^1,*

, Mahtab Asadian¹, Wannes Nicolaus¹, Heidi Declercq², Rino Morent¹ and Nathalie De Geyter^1,*

¹ Department of Applied Physics, Research Unit Plasma Technology (RUPT), Faculty of Engineering and Architecture, Ghent University, Sint-Pietersnieuwstraat 41, B4, 9000 Ghent, Belgium

² Department of Basic Medical Sciences, Tissue Engineering Group, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185, B3, 9000 Ghent, Belgium

Materials 2018, 11(3), 391; https://doi.org/10.3390/ma11030391 - 7 Mar 2018

Cited by 45 | Viewed by 5430

Abstract

This work describes the surface modification of 300PEO-PEOT/PBT 55/45 thin films using a medium pressure dielectric barrier discharge system operated in argon, helium, nitrogen or dry air to improve cell-surface interactions of this established biomaterial. The first part of the paper describes the [...] Read more.

This work describes the surface modification of 300PEO-PEOT/PBT 55/45 thin films using a medium pressure dielectric barrier discharge system operated in argon, helium, nitrogen or dry air to improve cell-surface interactions of this established biomaterial. The first part of the paper describes the optimization of the plasma processing parameters using water contact angle goniometry. The optimized samples are then characterized for changes in surface topography and surface chemical composition using atomic force microscopy (AFM) and X-ray fluorescence spectroscopy (XPS) respectively. For all plasma treatments, a pronounced increase in surface wettability was observed, of which the extent is dependent on the used plasma discharge gas. Except for dry air, only minor changes in surface topography were noted, while XPS confirmed that the changes in wettability were mainly chemical in nature with the incorporation of 5–10% of extra oxygen as a variety of polar groups. Similarly, for the nitrogen plasma, 3.8% of nitrogen polar groups were additionally incorporated. Human foreskin fibroblast (HFF) in vitro analysis showed that within the first 24 h after cell seeding, the effects on cell-surface interactivity were highly dependent on the used discharge gas, nitrogen plasma treatment being the most efficient. Differences between untreated and plasma-treated samples were less pronounced compared to other biodegradable materials, but a positive influence on cell adhesion and proliferation was still observed. Full article

(This article belongs to the Special Issue Selected papers from EUROMAT 2017 Conference—Biomaterials)

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13 pages, 8974 KiB

Open AccessArticle

Investigation on Selective Laser Melting AlSi10Mg Cellular Lattice Strut: Molten Pool Morphology, Surface Roughness and Dimensional Accuracy

by Xuesong Han¹, Haihong Zhu^1,*, Xiaojia Nie¹, Guoqing Wang² and Xiaoyan Zeng¹

¹ Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China

² China Academy of Launch Vehicle Technology, Beijing 100076, China

Materials 2018, 11(3), 392; https://doi.org/10.3390/ma11030392 - 7 Mar 2018

Cited by 105 | Viewed by 7305

Abstract

AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average [...] Read more.

AlSi10Mg inclined struts with angle of 45° were fabricated by selective laser melting (SLM) using different scanning speed and hatch spacing to gain insight into the evolution of the molten pool morphology, surface roughness, and dimensional accuracy. The results show that the average width and depth of the molten pool, the lower surface roughness and dimensional deviation decrease with the increase of scanning speed and hatch spacing. The upper surface roughness is found to be almost constant under different processing parameters. The width and depth of the molten pool on powder-supported zone are larger than that of the molten pool on the solid-supported zone, while the width changes more significantly than that of depth. However, if the scanning speed is high enough, the width and depth of the molten pool and the lower surface roughness almost keep constant as the density is still high. Therefore, high dimensional accuracy and density as well as good surface quality can be achieved simultaneously by using high scanning speed during SLMed cellular lattice strut. Full article

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16 pages, 2363 KiB

Open AccessFeature PaperArticle

Electrospun Composite Liquid Crystal Elastomer Fibers

by Anshul Sharma^*

and Jan P. F. Lagerwall^*

Physics and Materials Science Research Unit, University of Luxembourg, 162 A Avenue de la Faïencerie, 1511 Luxembourg, Luxembourg

Materials 2018, 11(3), 393; https://doi.org/10.3390/ma11030393 - 7 Mar 2018

Cited by 31 | Viewed by 10247

Abstract

We present a robust method to prepare thin oriented nematic liquid crystalline elastomer-polymer (LCE-polymer) core-sheath fibers. An electrospinning setup is utilized to spin a single solution of photo-crosslinkable low molecular weight reactive mesogens and a support polymer to form the coaxial LCE-polymer fibers, [...] Read more.

We present a robust method to prepare thin oriented nematic liquid crystalline elastomer-polymer (LCE-polymer) core-sheath fibers. An electrospinning setup is utilized to spin a single solution of photo-crosslinkable low molecular weight reactive mesogens and a support polymer to form the coaxial LCE-polymer fibers, where the support polymer forms the sheath via in situ phase separation as the solvent evaporates. We discuss the effect of phase separation and compare two different sheath polymers (polyvinylpyrrolidone and polylactic acid), investigating optical and morphological properties of obtained fibers, as well as the shape changes upon heating. The current fibers show only irreversible contraction, the relaxation most likely being hindered by the presence of the passive sheath polymer, increasing in stiffness on cooling. If the sheath polymer can be removed while keeping the LCE core intact, we expect LCE fibers produced in this way to have potential to be used as actuators, for instance in soft robotics and responsive textiles. Full article

(This article belongs to the Special Issue Liquid Crystal-Assisted Advanced Functional Materials)

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18 pages, 10098 KiB

Open AccessFeature PaperArticle

Protein-Based Nanoparticle Preparation via Nanoprecipitation Method

by Mohamad Tarhini^1,2, Ihsane Benlyamani¹, Selim Hamdani¹, Géraldine Agusti¹, Hatem Fessi¹, Hélène Greige-Gerges², Abderrazzak Bentaher³ and Abdelhamid Elaissari^1,*

¹ Univ Lyon, Université Claude Bernard Lyon-1, CNRS, LAGEP UMR 5007, 43 boulevard du 11 Novembre 1918, F-69100 Villeurbanne, France

² Faculty of Sciences, Lebanese University, B.P. 90656 Jdaidet El-Matn, Lebanon

³ Inflammation and Immunity of the Respiratory Epithelium-EA 7426, Faculté de Médecine Lyon Sud, 69495 Pierre Benite, France

Materials 2018, 11(3), 394; https://doi.org/10.3390/ma11030394 - 7 Mar 2018

Cited by 110 | Viewed by 11534

Abstract

Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been [...] Read more.

Nanoparticles are nowadays largely investigated in the field of drug delivery. Among nanoparticles, protein-based particles are of paramount importance since they are natural, biodegradable, biocompatible, and nontoxic. There are several methods to prepare proteins containing nanoparticles, but only a few studies have been dedicated to the preparation of protein- based nanoparticles. Then, the aim of this work was to report on the preparation of bovine serum albumin (BSA)-based nanoparticles using a well-defined nanoprecipitation process. Special attention has been dedicated to a systematic study in order to understand separately the effect of each operating parameter of the method (such as protein concentration, solvent/non-solvent volume ratio, non-solvent injection rate, ionic strength of the buffer solution, pH, and cross-linking) on the colloidal properties of the obtained nanoparticles. In addition, the mixing processes (batch or drop-wise) were also investigated. Using a well-defined formulation, submicron protein-based nanoparticles have been obtained. All prepared particles have been characterized in terms of size, size distribution, morphology, and electrokinetic properties. In addition, the stability of nanoparticles was investigated using Ultraviolet (UV) scan and electrophoresis, and the optimal conditions for preparing BSA nanoparticles by the nanoprecipitation method were concluded. Full article

(This article belongs to the Special Issue Biodegradable Polymeric Composites: Development and Industrial Applications)

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19 pages, 2301 KiB

Open AccessArticle

Alloying and Properties of C14–NbCr₂ and A15–Nb₃X (X = Al, Ge, Si, Sn) in Nb–Silicide-Based Alloys

by Panos Tsakiropoulos

Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD, UK

Materials 2018, 11(3), 395; https://doi.org/10.3390/ma11030395 - 7 Mar 2018

Cited by 32 | Viewed by 4304

Abstract

The oxidation of Nb–silicide-based alloys is improved with Al, Cr, Ge or Sn addition(s). Depending on addition(s) and its(their) concentration(s), alloyed C14-AB₂ Laves and A15-A₃X phases can be stable in the microstructures of the alloys. In both phases, A is [...] Read more.

The oxidation of Nb–silicide-based alloys is improved with Al, Cr, Ge or Sn addition(s). Depending on addition(s) and its(their) concentration(s), alloyed C14-AB₂ Laves and A15-A₃X phases can be stable in the microstructures of the alloys. In both phases, A is the transition metal(s), and B and X respectively can be Cr, Al, Ge, Si or Sn, and Al, Ge, Si or Sn. The alloying, creep and hardness of these phases were studied using the composition weighted differences in electronegativity (∆χ), average valence electron concentrations (VEC) and atomic sizes. For the Laves phase (i) the VEC and ∆χ were in the ranges 4.976 < VEC < 5.358 and −0.503 < ∆χ < −0.107; (ii) the concentration of B (=Al + Cr + Ge + Si + Sn) varied from 50.9 to 64.5 at %; and (iii) the Cr concentration was in the range of 35.8 < Cr < 51.6 at %. Maps of ∆χ versus Cr, ∆χ versus VEC, and VEC versus atomic size separated the alloying behaviours of the elements. Compared with unalloyed NbCr₂, the VEC decreased and ∆χ increased in Nb(Cr,Si)₂, and the changes in both parameters increased when Nb was substituted by Ti, and Cr by Si and Al, or Si and Ge, or Si and Sn. For the A15 phase (i) the VEC and ∆χ were in the ranges 4.38 < VEC < 4.89 and 0.857 < ∆χ < 1.04, with no VEC values between 4.63 and 4.72 and (ii) the concentration of X (=Al + Ge + Si + Sn) varied from 16.3 to 22.7 at %. The VEC versus ∆χ map separated the alloying behaviours of elements. The hardness of A15-Nb₃X was correlated with the parameters ∆χ and VEC. The hardness increased with increases in ∆χ and VEC. Compared with Nb₃Sn, the ∆χ and hardness of Nb₃(Si,Sn) increased. The substitution of Nb by Cr had the same effect on ∆χ and hardness as Hf or Ti. The ∆χ and hardness increased with Ti concentration. The addition of Al in Nb₃(Si,Sn,Al) decreased the ∆χ and increased the hardness. When Ti and Hf, or Ti, Hf and Cr, were simultaneously present with Al, the ∆χ was decreased and the hardness was unchanged. The better creep of Nb(Cr,Si)₂ compared with the unalloyed Laves phase was related to the decrease in the VEC and ∆χ parameters. Full article

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9 pages, 7739 KiB

Open AccessArticle

Mg-MOF-74/MgF₂ Composite Coating for Improving the Properties of Magnesium Alloy Implants: Hydrophilicity and Corrosion Resistance

by Wei Liu¹, Zhijie Yan¹, Xiaolu Ma¹, Tie Geng¹, Haihong Wu¹ and Zhongyue Li^2,*

¹ School of Mechanical & Electrical Engineering, Henan University of Technology, Zhengzhou 450001, China

² School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China

Materials 2018, 11(3), 396; https://doi.org/10.3390/ma11030396 - 7 Mar 2018

Cited by 68 | Viewed by 9193

Abstract

Surface modification on Mg alloys is highly promising for their application in the field of bone repair. In this study, a new metal–organic framework/MgF₂ (Mg-MOF-74/MgF₂) composite coating was prepared on the surface of AZ31B Mg alloy via pre-treatment of hydrofluoric [...] Read more.

Surface modification on Mg alloys is highly promising for their application in the field of bone repair. In this study, a new metal–organic framework/MgF₂ (Mg-MOF-74/MgF₂) composite coating was prepared on the surface of AZ31B Mg alloy via pre-treatment of hydrofluoric acid and in situ hydrothermal synthesis methods. The surface topography of the composite coating is compact and homogeneous, and Mg-MOF-74 has good crystallinity. The corrosion resistance of this composite coating was investigated through Tafel polarization test and immersion test in simulated body fluid at 37 °C. It was found that Mg-MOF-74/MgF₂ composite coating significantly slowed down the corrosion rate of Mg alloy. Additionally, Mg-MOF-74/MgF₂ composite coating expresses super-hydrophilicity with the water contact angle of nearly 0°. In conclusion, on the basis of MgF₂ anticorrosive coating, the introduction of Mg-MOF-74 further improves the biological property of Mg alloys. At last, we propose that the hydrophilicity of the composite coating is mainly owing to the large number of hydroxyl groups, the high specific surface area of Mg-MOF-74, and the rough coating produced by Mg-MOF-74 particles. Hence, Mg-MOF-74 has a great advantage in enhancing the hydrophilicity of Mg alloy surface. Full article

(This article belongs to the Section Porous Materials)

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15 pages, 3204 KiB

Open AccessArticle

Structural, Electronic, and Thermodynamic Properties of Tetragonal t-Si_xGe_3−xN₄

by Chenxi Han¹, Changchun Chai¹, Qingyang Fan^1,*, Jionghao Yang² and Yintang Yang¹

¹ Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi’an 710071, China

² Xi’an Institute of Applied Optics, Xi’an 710065, China

Materials 2018, 11(3), 397; https://doi.org/10.3390/ma11030397 - 7 Mar 2018

Cited by 7 | Viewed by 4392

Abstract

The structural, mechanical, anisotropic, electronic, and thermal properties of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄ in the tetragonal phase are systematically investigated in the present [...] Read more.

The structural, mechanical, anisotropic, electronic, and thermal properties of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄ in the tetragonal phase are systematically investigated in the present work. The mechanical stability is proved by the elastic constants of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄. Moreover, they all demonstrate brittleness, because B/G < 1.75, and v < 0.26. The elastic anisotropy of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄ is characterized by Poisson’s ratio, Young’s modulus, the percentage of elastic anisotropy for bulk modulus A_B, the percentage of elastic anisotropy for shear modulus A_G, and the universal anisotropic index A^U. The electronic structures of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄ are all wide band gap semiconductor materials, with band gaps of 4.26 eV, 3.94 eV, 3.83 eV, and 3.25 eV, respectively, when using the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional. Moreover, t-Ge₃N₄ is a quasi-direct gap semiconductor material. The thermodynamic properties of t-Si₃N₄, t-Si₂GeN₄, t-SiGe₂N₄, and t-Ge₃N₄ are investigated utilizing the quasi-harmonic Debye model. The effects of temperature and pressure on the thermal expansion coefficient, heat capacity, Debye temperature, and Grüneisen parameters are discussed in detail. Full article

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22 pages, 14212 KiB

Open AccessArticle

Interface Bond Improvement of Sisal Fibre Reinforced Polylactide Composites with Added Epoxy Oligomer

by Mingyang Hao^1,2, Hongwu Wu^1,2,*

, Feng Qiu^1,2 and Xiwen Wang¹

¹ The Key Laboratory of Polymer Processing Engineering of Ministry of Education, South China University of Technology, Guangzhou 510640, China

² National Engineering Research Center of Novel Equipment for Polymer Processing, South China University of Technology, Guangzhou 510640, China

Materials 2018, 11(3), 398; https://doi.org/10.3390/ma11030398 - 7 Mar 2018

Cited by 32 | Viewed by 4963

Abstract

To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR^@-4368 (ADR). The FTIR [...] Read more.

To improve the interfacial bonding of sisal fiber-reinforced polylactide biocomposites, polylactide (PLA) and sisal fibers (SF) were melt-blended to fabricate bio-based composites via in situ reactive interfacial compatibilization with addition of a commercial grade epoxy-functionalized oligomer Joncryl ADR^@-4368 (ADR). The FTIR (Fourier Transform infrared spectroscopy) analysis and SEM (scanning electron microscope) characterization demonstrated that the PLA molecular chain was bonded to the fiber surface and the epoxy-functionalized oligomer played a hinge-like role between the sisal fibers and the PLA matrix, which resulted in improved interfacial adhesion between the fibers and the PLA matrix. The interfacial reaction and microstructures of composites were further investigated by thermal and rheological analyses, which indicated that the mobility of the PLA molecular chain in composites was restricted because of the introduction of the ADR oligomer, which in turn reflected the improved interfacial interaction between SF and the PLA matrix. These results were further justified with the calculation of activation energies of glass transition relaxation (∆E_a) by dynamic mechanical analysis. The mechanical properties of PLA/SF composites were simultaneously reinforced and toughened with the addition of ADR oligomer. The interfacial interaction and structure–properties relationship of the composites are the key points of this study. Full article

(This article belongs to the Section Advanced Composites)

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9 pages, 1728 KiB

Open AccessCommunication

Highly Sensitive and Selective Potassium Ion Detection Based on Graphene Hall Effect Biosensors

by Xiangqi Liu^1,2,†, Chen Ye^2,3,†, Xiaoqing Li^2,3, Naiyuan Cui^2,4, Tianzhun Wu⁵

, Shiyu Du⁶, Qiuping Wei⁷, Li Fu⁸, Jiancheng Yin^1,* and Cheng-Te Lin^2,3,*

¹ Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China

² Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences, Ningbo 315201, China

³ College of Material Science and Optoelectronic Technology, University of Chinese Academy of Sciences, 19 A Yuquan Rd., Shijingshan District, Beijing 100049, China

⁴ MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter, Xi’an Jiaotong University, Xi’an 710049, China

⁵ Shenzhen Institutes of Advanced Technology, Chinece Acedemy of Science, Shenzhen 518055, China

⁶ Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China

⁷ School of Materials Science and Engineering, Central South University, Changsha 410083, China

⁸ College of Materials and Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018, China

^† These authors contributed equally to this work.

Materials 2018, 11(3), 399; https://doi.org/10.3390/ma11030399 - 7 Mar 2018

Cited by 20 | Viewed by 5994

Abstract

Potassium (K⁺) ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively [...] Read more.

Potassium (K⁺) ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively recognize K⁺ ions. In this work, a highly sensitive and selective biosensor based on single-layer graphene has been developed for K⁺ ion detection under Van der Pauw measurement configuration. With pre-immobilization of guanine-rich DNA on the graphene surface, the graphene devices exhibit a very low limit of detection (≈1 nM) with a dynamic range of 1 nM–10 μM and excellent K⁺ ion specificity against other alkali cations, such as Na⁺ ions. The origin of K⁺ ion selectivity can be attributed to the fact that the formation of guanine-quadruplexes from guanine-rich DNA has a strong affinity for capturing K⁺ ions. The graphene-based biosensors with improved sensing performance for K⁺ ion recognition can be applied to health monitoring and early disease diagnosis. Full article

(This article belongs to the Special Issue Recent Advances in 2D Nanomaterials)

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13 pages, 9363 KiB

Open AccessFeature PaperArticle

Electrospun F18 Bioactive Glass/PCL—Poly (ε-caprolactone)—Membrane for Guided Tissue Regeneration

by Lucas Hidalgo Pitaluga^1,*, Marina Trevelin Souza¹, Edgar Dutra Zanotto¹

, Martin Eduardo Santocildes Romero² and Paul V. Hatton²

¹ CeRTEV—Center for Research, Technology and Education in Vitreous Materials, Department of Materials Engineering, Federal University of São Carlos, 13565-905 São Carlos, Brazil

² School of Clinical Dentistry, The University of Sheffield, 19 Claremont Crescent, Sheffield S10 2TA, UK

Materials 2018, 11(3), 400; https://doi.org/10.3390/ma11030400 - 8 Mar 2018

Cited by 37 | Viewed by 5427

Abstract

Barrier membranes that are used for guided tissue regeneration (GTR) therapy usually lack bioactivity and the capability to promote new bone tissue formation. However, the incorporation of an osteogenic agent into polymeric membranes seems to be the most assertive strategy to enhance their [...] Read more.

Barrier membranes that are used for guided tissue regeneration (GTR) therapy usually lack bioactivity and the capability to promote new bone tissue formation. However, the incorporation of an osteogenic agent into polymeric membranes seems to be the most assertive strategy to enhance their regenerative potential. Here, the manufacturing of composite electrospun membranes made of poly (ε-caprolactone) (PCL) and particles of a novel bioactive glass composition (F18) is described. The membranes were mechanically and biologically tested with tensile strength tests and tissue culture with MG-63 osteoblast-like cell line, respectively. The PCL-F18 composite membranes demonstrated no increased cytotoxicity and an enhanced osteogenic potential when compared to pure PCL membranes. Moreover, the addition of the bioactive phase increased the membrane tensile strength. These preliminary results suggested that these new membranes can be a strong candidate for small bone injuries treatment by GTR technique. Full article

(This article belongs to the Special Issue Bioactive Glasses 2017)

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13 pages, 4212 KiB

Open AccessArticle

In Vitro Analysis of the Fracture Resistance of CAD/CAM Denture Base Resins

by Otto Steinmassl¹

, Vincent Offermanns¹

, Wolfgang Stöckl², Herbert Dumfahrt², Ingrid Grunert² and Patricia-Anca Steinmassl^2,*

¹ University Hospital for Cranio-Maxillofacial and Oral Surgery, Department of Dental and Oral Medicine and Cranio-Maxillofacial and Oral Surgery, Medical University of Innsbruck, Anichstr. 35, A-6020 Innsbruck, Austria

² University Hospital for Dental Prosthetics and Restorative Dentistry, Department of Dental and Oral Medicine and Cranio-Maxillofacial and Oral Surgery, Medical University of Innsbruck, Anichstr. 35, A-6020 Innsbruck, Austria

Materials 2018, 11(3), 401; https://doi.org/10.3390/ma11030401 - 8 Mar 2018

Cited by 58 | Viewed by 6341

Abstract

Computer-aided design and computer-aided manufacturing (CAD/CAM) denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than [...] Read more.

Computer-aided design and computer-aided manufacturing (CAD/CAM) denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than conventional, manually fabricated dentures. The aim of this study was to investigate if commercially available CAD/CAM denture base resins have more favourable mechanical properties than conventionally processed denture base resins. For this purpose, a series of three-point bending tests conforming to ISO specifications were performed on a total of 80 standardised, rectangular CAD/CAM denture base resin specimens from five different manufacturers (AvaDent, Baltic Denture System, Vita VIONIC, Whole You Nexteeth, and Wieland Digital Dentures). A heat-polymerising resin and an autopolymerising resin served as the control groups. The breaking load, fracture toughness, and the elastic modulus were assessed. Additionally, the fracture surface roughness and texture were investigated. Only one CAD/CAM resin showed a significantly increased breaking load. Two CAD/CAM resins had a significantly higher fracture toughness than the control groups, and all CAD/CAM resins had higher elastic moduli than the controls. Our results indicate that CAD/CAM denture base resins do not generally have better mechanical properties than manually processed resins. Therefore, the lower minimum denture base thicknesses should be regarded with some caution. Full article

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11 pages, 7115 KiB

Open AccessArticle

The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy

by Jun Chen^1,2,*

, Xiangna Lan¹, Chao Wang² and Qinyong Zhang¹

¹ Key Laboratory of Fluid and Power Machinery of Ministry of Education, School of Materials Science and Engineering, Xihua University, Chengdu 610039, China

² Clean Energy Materials and Engineering Center, School of Electronic Science and Engineering, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China

Materials 2018, 11(3), 402; https://doi.org/10.3390/ma11030402 - 8 Mar 2018

Cited by 16 | Viewed by 4246

Abstract

Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared [...] Read more.

Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO₄·3H₂O, MnHPO₄·2.25H₂O, BaHPO₄·3H₂O, BaMg₂(PO₄)₂, Mg₃(PO₄)₂·22H₂O, Ca₃(PO₄)₂·xH₂O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl. Full article

(This article belongs to the Section Thin Films and Interfaces)

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11 pages, 2749 KiB

Open AccessArticle

Preparation and Dielectric Properties of SiC/LSR Nanocomposites for Insulation of High Voltage Direct Current Cable Accessories

by Nanqiang Shang^*, Qingguo Chen and Xinzhe Wei

Key Laboratory of Engineering Dielectric and its Application, Ministry of Education, Harbin University of Science and Technology, Harbin 150040, China

Materials 2018, 11(3), 403; https://doi.org/10.3390/ma11030403 - 8 Mar 2018

Cited by 30 | Viewed by 4432

Abstract

The conductivity mismatch in the composite insulation of high voltage direct current (HVDC) cable accessories causes electric field distribution distortion and even insulation breakdown. Therefore, a liquid silicone rubber (LSR) filled with SiC nanoparticles is prepared for the insulation of cable accessories. The [...] Read more.

The conductivity mismatch in the composite insulation of high voltage direct current (HVDC) cable accessories causes electric field distribution distortion and even insulation breakdown. Therefore, a liquid silicone rubber (LSR) filled with SiC nanoparticles is prepared for the insulation of cable accessories. The micro-morphology of the SiC/LSR nanocomposites is observed by scanning electron microscopy, and their trap parameters are characterized using thermal stimulated current (TSC) tests. Moreover, the dielectric properties of SiC/LSR nanocomposites with different SiC concentrations are tested. The results show that the 3 wt % SiC/LSR sample has the best nonlinear conductivity, more than one order of magnitude higher than that of pure LSR with improved temperature and nonlinear conductivity coefficients. The relative permittivity increased 0.2 and dielectric loss factor increased 0.003, while its breakdown strength decreased 5 kV/mm compared to those of pure LSR. Moreover, the TSC results indicate the introduction of SiC nanoparticles reduced the trap level and trap density. Furthermore, the SiC nanoparticles filling significantly increased the sensitivity of LSR to electric field stress and temperature changes, enhancing the conductivity and electric field distribution within the HVDC cable accessories, thus improving the reliability of the HVDC cable accessories. Full article

(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)

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11 pages, 7385 KiB

Open AccessArticle

Interfaces between Model Co-W-C Alloys with Various Carbon Contents and Tungsten Carbide

by Igor Konyashin^1,2,*, Alexander Zaitsev¹, Alexander Meledin^3,4

, Joachim Mayer^3,4, Pavel Loginov¹, Evgeny Levashov¹ and Bernd Ries²

¹ Department of Powder Metallurgy and Functional Coatings, National University of Science and Technology “MISiS”, Leninsky pr. 4, 119049 Moscow, Russia

² Element Six GmbH, Städeweg 12-24, 36151 Burghaun, Germany

³ Central Facility for Electron Microscopy (GFE), RWTH Aachen University, Ahornstrasse 55, D-52074 Aachen, Germany

⁴ Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons Research Centre Juelich, D-52425 Juelich, Germany

Materials 2018, 11(3), 404; https://doi.org/10.3390/ma11030404 - 9 Mar 2018

Cited by 11 | Viewed by 4164

Abstract

Interfaces between alloys simulating binders in WC-Co cemented carbides and tungsten carbide were examined on the micro-, nano-, and atomic-scale. The precipitation of fine WC grains and η-phase occurs at the interface of the alloy with the low carbon content. The precipitation of [...] Read more.

Interfaces between alloys simulating binders in WC-Co cemented carbides and tungsten carbide were examined on the micro-, nano-, and atomic-scale. The precipitation of fine WC grains and η-phase occurs at the interface of the alloy with the low carbon content. The precipitation of such grains almost does not occur in the alloy with the medium-low carbon content and does not take place in the alloy with the high carbon content. The formation of Co nanoparticles in the binder alloy with the medium-low carbon content was established. Interfaces in the alloy with the medium-low carbon content characterized by complete wetting with respect to WC and with the high carbon content characterized by incomplete wetting were examined at an atomic scale. The absence of any additional phases or carbon segregations at both of the interfaces was established. Thus, the phenomenon of incomplete wetting of WC by liquid binders with high carbon contents is presumably related to special features of the Co-based binder alloys oversaturated with carbon at sintering temperatures. Full article

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11 pages, 4635 KiB

Open AccessArticle

Trifunctional Epoxy Resin Composites Modified by Soluble Electrospun Veils: Effect on the Viscoelastic and Morphological Properties

by Giulia Ognibene^1,2,3

, Salvatore Mannino¹, Maria Elena Fragalà^2,3

and Gianluca Cicala^1,2,*

¹ Department of Civil Engineering and Architecture, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy

² Italian Consortium for Materials Science and Technology Reseacch Unit Catania, Viale Andrea Doria 6, 95125 Catania, Italy

³ Department of Chemical Science, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy

Materials 2018, 11(3), 405; https://doi.org/10.3390/ma11030405 - 9 Mar 2018

Cited by 3 | Viewed by 3827

Abstract

Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin [...] Read more.

Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar veils for carbon fiber/epoxy composites. Neat, resin samples were impregnated into coPES veils with unmodified resin, while dry carbon fabrics were covered with electrospun veils and then infused with the unmodified epoxy resin to prepare reinforced laminates. The thermoplastic content varied from 10 wt% to 20 wt%. TGAP epoxy monomer showed improved and fast dissolution for all the temperatures tested. The unreinforced samples were cured first at 180 °C for 2 h and then were post-cured at 220 °C for 3 h. These sample showed a high dependence on the curing cycle. Carbon reinforced samples showed significant differences compared to the neat resin samples in terms of both viscoelastic and morphological properties. Full article

(This article belongs to the Section Advanced Composites)

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10 pages, 5144 KiB

Open AccessFeature PaperArticle

Fabrication of Fe–Co Magnetostrictive Fiber Reinforced Plastic Composites and Their Sensor Performance Evaluation

by Kenichi Katabira¹, Yu Yoshida¹, Atsuji Masuda², Akihito Watanabe³ and Fumio Narita^1,*

¹ Department of Materials Processing, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579, Japan

² Industrial Technology Center of Fukui Prefecture, 10 Kitainada, 61 Kawaiwashiduka-cho, Fukui 910-0102, Japan

³ Sakase Adtech Co., Ltd., 14-10 Shimoyasuda, Maruoka-cho, Sakai 910-03630, Japan

Materials 2018, 11(3), 406; https://doi.org/10.3390/ma11030406 - 9 Mar 2018

Cited by 34 | Viewed by 5208

Abstract

The inverse magnetostrictive effect is an effective property for energy harvesting; the material needs to have large magnetostriction and ease of mass production. Fe–Co alloys being magnetostrictive materials have favorable characteristics which are high strength, ductility, and excellent workability, allowing easy fabrication of [...] Read more.

The inverse magnetostrictive effect is an effective property for energy harvesting; the material needs to have large magnetostriction and ease of mass production. Fe–Co alloys being magnetostrictive materials have favorable characteristics which are high strength, ductility, and excellent workability, allowing easy fabrication of Fe–Co alloy fibers. In this study, we fabricated magnetostrictive polymer composites, in which Fe–Co fibers were woven into polyester fabric, and discussed their sensor performance. Compression and bending tests were carried out to measure the magnetic flux density change, and the effects of magnetization, bias magnetic field, and the location of the fibers on the performance were discussed. It was shown that magnetic flux density change due to compression and bending is related to the magnetization of the Fe–Co fiber and the bias magnetic field. The magnetic flux density change of Fe–Co fiber reinforced plastics was larger than that of the plastics with Terfenol-D particles. Full article

(This article belongs to the Special Issue Magnetostrictive Composite Materials)

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10 pages, 3829 KiB

Open AccessArticle

Surface Roughness of Composite Panels as a Quality Control Tool

by Onur Ulker^1,2

¹ Department of Interior Architecture and Environmental Design, University of Kırıkkale, 71450 Yahşihan, Turkey

² Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK 74078-6013, USA

Materials 2018, 11(3), 407; https://doi.org/10.3390/ma11030407 - 9 Mar 2018

Cited by 24 | Viewed by 4945

Abstract

This paper describes a study of the quantify surface roughness of experimentally manufactured particleboards and sandwiched panels having fibers on the surface layers. Surface quality of specimens before and after being overlaid with thin melamine impregnated papers was determined by employing profilometer equipment. [...] Read more.

This paper describes a study of the quantify surface roughness of experimentally manufactured particleboards and sandwiched panels having fibers on the surface layers. Surface quality of specimens before and after being overlaid with thin melamine impregnated papers was determined by employing profilometer equipment. Roughness measurements and Janka hardness were carried out on the specimens conditioned at 60% and 95% relative humidity levels. Based on the findings in this work, surface roughness of the specimens that were exposed two relative humidity exposure showed significant differences from each others. Data determined in this study could be beneficial to understand behavior of such panels exposed different humidity levels. Full article

(This article belongs to the Section Biomaterials)

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11 pages, 11408 KiB

Open AccessArticle

Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy

by Gang Liu¹, Wen Xie¹, Guobing Wei^1,*, Yan Yang^1,2, Junwei Liu³, Tiancai Xu¹, Weidong Xie^1,2 and Xiaodong Peng^1,2

¹ College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China

² National Engineering Research Center for Magnesium Alloys, Chongqing 400044, China

³ School of mechatronics engineering, Zhengzhou University of Aeronautics, Zhengzhou 450015, China

Materials 2018, 11(3), 408; https://doi.org/10.3390/ma11030408 - 9 Mar 2018

Cited by 34 | Viewed by 4742

Abstract

The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al [...] Read more.

The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al₄Sr and Al₂Y phases. The dynamic recrystallization (DRX) kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress–strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al₄Sr phases and spheroidal Al₂Y particles, which can accelerate the nucleation. The continuous Al₄Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion. Full article

(This article belongs to the Section Advanced Materials Characterization)

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15 pages, 19778 KiB

Open AccessArticle

Strain Behavior of Concrete Panels Subjected to Different Nose Shapes of Projectile Impact

by Sangkyu Lee, Gyuyong Kim^*, Hongseop Kim, Minjae Son, Gyeongcheol Choe and Jeongsoo Nam

Department of Architectural Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Korea

Materials 2018, 11(3), 409; https://doi.org/10.3390/ma11030409 - 9 Mar 2018

Cited by 19 | Viewed by 5144

Abstract

This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration [...] Read more.

This study evaluates the fracture properties and rear-face strain distribution of nonreinforced and hooked steel fiber-reinforced concrete panels penetrated by projectiles of three different nose shapes: sharp, hemispherical, and flat. The sharp projectile nose resulted in a deeper penetration because of the concentration of the impact force. Conversely, the flat projectile nose resulted in shallower penetrations. The penetration based on different projectile nose shapes is directly related to the impact force transmitted to the rear face. Scabbing can be more accurately predicted by the tensile strain on the rear face of concrete due to the projectile nose shape. The tensile strain on the rear face of the concrete was reduced by the hooked steel fiber reinforcement because the hooked steel fiber absorbed some of the impact stress transmitted to the rear face of the concrete. Consequently, the strain behavior on the rear face of concrete according to the projectile nose shape was confirmed. Full article

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26 pages, 4650 KiB

Open AccessArticle

Study of Hyperbranched Poly(ethyleneimine) Polymers of Different Molecular Weight and Their Interaction with Epoxy Resin

by Frida Román^*

, Pere Colomer^†

, Yolanda Calventus^†

and John M. Hutchinson^†

¹ Departament de Màquines i Motors Tèrmics, Escola Superior d’Enginyeries Industrial, Aeroespacial i Audiovisual de Terrassa, Universitat Politècnica de Catalunya, Barcelona Tech, Carrer de Colom 11, 08222 Terrassa, Spain

^† These authors contributed equally to this work.

Materials 2018, 11(3), 410; https://doi.org/10.3390/ma11030410 - 9 Mar 2018

Cited by 34 | Viewed by 5615

Abstract

Two different commercial hyperbranched poly(ethyleneimine)s (HBPEI), with molecular weights (MW) of 800 and 25,000 g/mol, and denoted as PEI800 and PEI25000, respectively, as well as the mixtures with a Diglycidyl Ether of Bisphenol-A (DGEBA) epoxy resin, have been studied using thermal analysis techniques [...] Read more.

Two different commercial hyperbranched poly(ethyleneimine)s (HBPEI), with molecular weights (MW) of 800 and 25,000 g/mol, and denoted as PEI800 and PEI25000, respectively, as well as the mixtures with a Diglycidyl Ether of Bisphenol-A (DGEBA) epoxy resin, have been studied using thermal analysis techniques (DSC, TGA), dielectric relaxation spectroscopy (DRS), and dynamic mechanical analysis (DMA). Only a single glass transition is observed in these mixtures by DSC. DRS of the HBPEIs shows three dipolar relaxations: γ, β, and α. The average activation energy for the γ-relaxation is similar for all HBPEIs and is associated with the motion of the terminal groups. The β-relaxation has the same average activation energy for both PEI800 and PEI25000; this relaxation is attributed to the mobility of the branches. The α-relaxation peak for all the HBPEIs is an asymmetric peak with a shoulder on the high temperature side. This shoulder suggests the existence of ionic charge trapped in the PEI. For the mixtures, the γ- and β-relaxations follow the behaviour of the epoxy resin alone, indicating that the epoxy resin dominates the molecular mobility. The α-relaxation by DRS is observed only as a shoulder, as a consequence of an overlap with conductivity effects, whereas by DMA, it is a clear peak. Full article

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17 pages, 3703 KiB

Open AccessArticle

Factors Affecting the Power Conversion Efficiency in ZnO DSSCs: Nanowire vs. Nanoparticles

by Myrsini Giannouli^1,*

, Κaterina Govatsi², George Syrrokostas²

, Spyros N. Yannopoulos²

and George Leftheriotis¹

¹ Renewable Energy and Environment Laboratory, Physics Department, University of Patras, Rion GR-26500, Greece

² Foundation for Research and Technology Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), P.O. Box 1414, Rio-Patras GR-26504, Greece

Materials 2018, 11(3), 411; https://doi.org/10.3390/ma11030411 - 9 Mar 2018

Cited by 45 | Viewed by 5587

Abstract

A comparative assessment of nanowire versus nanoparticle-based ZnO dye-sensitized solar cells (DSSCs) is conducted to investigate the main parameters that affect device performance. Towards this aim, the influence of film morphology, dye adsorption, electron recombination and sensitizer pH on the power conversion efficiency [...] Read more.

A comparative assessment of nanowire versus nanoparticle-based ZnO dye-sensitized solar cells (DSSCs) is conducted to investigate the main parameters that affect device performance. Towards this aim, the influence of film morphology, dye adsorption, electron recombination and sensitizer pH on the power conversion efficiency (PCE) of the DSSCs is examined. Nanoparticle-based DSSCs with PCEs of up to 6.2% are developed and their main characteristics are examined. The efficiency of corresponding devices based on nanowire arrays (NW) is considerably lower (0.63%) by comparison, mainly due to low light harvesting ability of ZnO nanowire films. The dye loading of nanowire films is found to be approximately an order of magnitude lower than that of nanoparticle-based ones, regardless of their internal surface area. Inefficient anchoring of dye molecules on the semiconductor surface due to repelling electrostatic forces is identified as the main reason for this low dye loading. We propose a method of modifying the sensitizer solution by altering its pH, thereby enhancing dye adsorption. We report an increase in the PCE of nanowire DSSCs from 0.63% to 1.84% as a direct result of using such a modified dye solution. Full article

(This article belongs to the Special Issue Zinc Oxide Nanostructures: Synthesis and Characterization)

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18 pages, 15478 KiB

Open AccessArticle

Sulfide Stress Cracking Behavior of a Martensitic Steel Controlled by Tempering Temperature

by Yu Sun^1,2, Qian Wang^1,3, Shunjie Gu^1,2, Zaoneng He^1,3, Qingfeng Wang^1,3,* and Fucheng Zhang^1,3

¹ Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China

² Technical Center, Tianjin Pipe (Group) Corporation Limited, Tianjin 300301, China

³ National Engineering Research Center for Equipment and Technology of Cold Strip Rolling, Yanshan University, Qinhuangdao 066004, China

Materials 2018, 11(3), 412; https://doi.org/10.3390/ma11030412 - 9 Mar 2018

Cited by 5 | Viewed by 5560

Abstract

A medium-carbon Cr–Mo–V martensitic steel was thermally processed by quenching (Q) at 890 °C and tempering (T) at increasing temperatures from 650 °C to 720 °C and the effect of tempering temperature, T_t, on sulfide stress cracking (SSC) behaviors was estimated [...] Read more.

A medium-carbon Cr–Mo–V martensitic steel was thermally processed by quenching (Q) at 890 °C and tempering (T) at increasing temperatures from 650 °C to 720 °C and the effect of tempering temperature, T_t, on sulfide stress cracking (SSC) behaviors was estimated mainly via double cantilever beam (DCB) and electrochemical hydrogen permeation (EHP) tests and microstructure characterization. The results indicate that the threshold stress intensity factor for SSC, K_ISSC, increased with increasing T_t. The overall and local H concentration around the inclusions decreased with increasing T_t, due to reductions in the amounts of solute atoms, grain boundaries and dislocations, which effectively prevented SSC initiation. Also, increasing T_t caused an increased fraction of high-angle boundaries, which evidently lowered the SSC propagation rate by more frequently diverting the propagating direction and accordingly restricted SSC propagation. The overall SSC resistance of this Q&T–treated steel was therefore significantly enhanced. Full article

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13 pages, 5856 KiB

Open AccessArticle

Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites

by David Florián-Algarín¹

, Raúl Marrero², Xiaochun Li³, Hongseok Choi⁴ and Oscar Marcelo Suárez^5,*

¹ Department of Civil Engineering, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USA

² Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, USA

³ Department of Mechanical and Aerospace Engineering, University of California-Los Angeles, Los Angeles, CA 90095-1597, USA

⁴ Department of Mechanical Engineering, Clemson University, Clemson, SC 29634, USA

⁵ Department of Engineering Science and Materials, University of Puerto Rico-Mayagüez, Mayagüez, PR 00681, USA

Materials 2018, 11(3), 413; https://doi.org/10.3390/ma11030413 - 10 Mar 2018

Cited by 10 | Viewed by 5248

Abstract

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through [...] Read more.

This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl₂O₃ nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl₂O₃ nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl₂O₃ nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding. Full article

(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)

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11 pages, 5060 KiB

Open AccessArticle

A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors

by Weifeng Chen¹, Weijing Wu^1,*, Lei Zhou², Miao Xu¹, Lei Wang¹, Honglong Ning¹

and Junbiao Peng¹

¹ State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

² Guangzhou New Vision Opto-Electronic Technology Co., Ltd., Guangzhou 510530, China

Materials 2018, 11(3), 416; https://doi.org/10.3390/ma11030416 - 11 Mar 2018

Cited by 4 | Viewed by 4382

Abstract

A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance–voltage characteristics and current–voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of [...] Read more.

A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance–voltage characteristics and current–voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson’s equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco). As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS) simultaneously. Full article

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14 pages, 3851 KiB

Open AccessArticle

The Impact of Iron Adsorption on the Electronic and Photocatalytic Properties of the Zinc Oxide (0001) Surface: A First-Principles Study

by Jingsi Cheng¹, Ping Wang^1,*

, Chao Hua², Yintang Yang³ and Zhiyong Zhang⁴

¹ State Key Laboratory of Integrated Service Networks, School of Telecommunications Engineering, Xidian University, Xi’an 710071, China

² Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China

³ School of Microelectronics, Xidian University, Xi’an 710071, China

⁴ College of Electronic and Informational Engineering, Northwestern University, Xi’an 710127, China

Materials 2018, 11(3), 417; https://doi.org/10.3390/ma11030417 - 12 Mar 2018

Cited by 8 | Viewed by 5154

Abstract

The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001) surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in [...] Read more.

The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001) surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in the H₃ adsorption site of ZnO (0001) surface has the lowest adsorption energy of −5.665 eV compared with T₄ and Top sites. For the Top site, compared with the pristine ZnO (0001) surface, the absorption peak located at 1.17 eV has a red shift, and the elevation of the absorption coefficient is more pronounced in the visible-light region, because the Fe-related levels are introduced in the forbidden band and near the Fermi level. The electrostatic potential computation reveals that the work function of the ZnO (0001) surface is significantly decreased from 2.340 to 1.768 eV when iron is adsorbed on the Top site. Furthermore, the degradation mechanism based on the band structure is analyzed. It can be concluded that the adsorption of iron will promote the separation of photoinduced carriers, thus improving the photocatalytic activity of ZnO (0001) surface. Our study benefits research on the photocatalytic activity of ZnO and the utilization rate of solar energy. Full article

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18 pages, 19384 KiB

Open AccessArticle

Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures

by Elías López-Alba^1,*, Sebastian Schmeer²

and Francisco Díaz¹

¹ Departamento de Ingeniería Mecánica y Minera, Campus las Lagunillas, Universidad de Jaén, 23071 Jaén, Spain

² Institute for Composite Materials (IVW), Kaiserslautern University of Technology, 67663 Kaiserslautern, Germany

Materials 2018, 11(3), 418; https://doi.org/10.3390/ma11030418 - 13 Mar 2018

Cited by 22 | Viewed by 7619

Abstract

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters [...] Read more.

The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack) made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen) and PLA (polylactic acid) matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets) were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA) as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack) seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD-PE matrix. Full article

(This article belongs to the Special Issue Advanced Materials for Transport Applications)

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13 pages, 9828 KiB

Open AccessArticle

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

by Yuchuan Chen

, Hang Gao^*, Xu Wang

, Dongming Guo and Ziyuan Liu

Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China

Materials 2018, 11(3), 419; https://doi.org/10.3390/ma11030419 - 13 Mar 2018

Cited by 13 | Viewed by 4912

Abstract

Laser induced damage threshold (LIDT) is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP) crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT), followed by water dissolution ultra-precision [...] Read more.

Laser induced damage threshold (LIDT) is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP) crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT), followed by water dissolution ultra-precision polishing (WDUP) and then tested with 355 nm nanosecond pulsed-lasers. Power spectral density (PSD) analysis shows that WDUP process eliminates the laser-detrimental spatial frequencies band of micro-waviness on SPDT machined surface and consequently decreases its modulation effect on the laser beams. The laser test results show that LIDT of WDUP machined crystal improves and its stability has a significant increase by 72.1% compared with that of SPDT. Moreover, a subsequent ultrasonic assisted solvent cleaning process is suggested to have a positive effect on the laser performance of machined KDP crystal. Damage crater investigation indicates that the damage morphologies exhibit highly thermal explosion features of melted cores and brittle fractures of periphery material, which can be described with the classic thermal explosion model. The comparison result demonstrates that damage mechanisms for SPDT and WDUP machined crystal are the same and WDUP process reveals the real bulk laser resistance of KDP optical crystal by removing the micro-waviness and subsurface damage on SPDT machined surface. This improvement of WDUP method makes the LIDT more accurate and will be beneficial to the laser performance of KDP crystal. Full article

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11 pages, 5272 KiB

Open AccessArticle

Thermal Properties of Zeolite-Containing Composites

by Taro Shimonosono¹, Yoshihiro Hirata^1,*, Kyohei Nishikawa¹, Soichiro Sameshima¹, Kenichi Sodeyama², Takuro Masunaga² and Yukio Yoshimura²

¹ Department of Chemistry, Biotechnology, and Chemical Engineering, Kagoshima University, Kagoshima 890-0065, Japan

² Shirasu R&D Laboratory, Regional Resource Division, Kagoshima Prefectural Institute of Industrial Technology, Kagoshima 899-5105, Japan

Materials 2018, 11(3), 420; https://doi.org/10.3390/ma11030420 - 13 Mar 2018

Cited by 3 | Viewed by 4273

Abstract

A zeolite (mordenite)–pore–phenol resin composite and a zeolite–pore–shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is [...] Read more.

A zeolite (mordenite)–pore–phenol resin composite and a zeolite–pore–shirasu glass composite were fabricated by hot-pressing. Their thermal conductivities were measured by a laser flash method to determine the thermal conductivity of the monolithic zeolite with the proposed mixing rule. The analysis using composites is useful for a zeolite powder with no sinterability to clarify its thermal properties. At a low porosity <20%, the thermal conductivity of the composite was in excellent agreement with the calculated value for the structure with phenol resin or shirasu glass continuous phase. At a higher porosity above 40%, the measured value approached the calculated value for the structure with pore continuous phase. The thermal conductivity of the monolithic mordenite was evaluated to be 3.63 W/mK and 1.70–2.07 W/mK at room temperature for the zeolite–pore–phenol resin composite and the zeolite–pore–shirasu glass composite, respectively. The analyzed thermal conductivities of monolithic mordenite showed a minimum value of 1.23 W/mK at 400 °C and increased to 2.51 W/mK at 800 °C. Full article

(This article belongs to the Special Issue Advanced Porous Ceramics and Its Applications)

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15 pages, 7002 KiB

Open AccessArticle

Cure Cycle Optimization of Rapidly Cured Out-Of-Autoclave Composites

by Anqi Dong, Yan Zhao^*, Xinqing Zhao and Qiyong Yu

School of Materials Science and Engineering, Beihang University, Beijing 100191, China

Materials 2018, 11(3), 421; https://doi.org/10.3390/ma11030421 - 13 Mar 2018

Cited by 35 | Viewed by 8039

Abstract

Out-of-autoclave prepreg typically needs a long cure cycle to guarantee good properties as the result of low processing pressure applied. It is essential to reduce the manufacturing time, achieve real cost reduction, and take full advantage of out-of-autoclave process. The focus of this [...] Read more.

Out-of-autoclave prepreg typically needs a long cure cycle to guarantee good properties as the result of low processing pressure applied. It is essential to reduce the manufacturing time, achieve real cost reduction, and take full advantage of out-of-autoclave process. The focus of this paper is to reduce the cure cycle time and production cost while maintaining high laminate quality. A rapidly cured out-of-autoclave resin and relative prepreg were independently developed. To determine a suitable rapid cure procedure for the developed prepreg, the effect of heating rate, initial cure temperature, dwelling time, and post-cure time on the final laminate quality were evaluated and the factors were then optimized. As a result, a rapid cure procedure was determined. The results showed that the resin infiltration could be completed at the end of the initial cure stage and no obvious void could be seen in the laminate at this time. The laminate could achieve good internal quality using the optimized cure procedure. The mechanical test results showed that the laminates had a fiber volume fraction of 59–60% with a final glass transition temperature of 205 °C and excellent mechanical strength especially the flexural properties. Full article

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17 pages, 13079 KiB

Open AccessFeature PaperArticle

Microporosity and CO₂ Capture Properties of Amorphous Silicon Oxynitride Derived from Novel Polyalkoxysilsesquiazanes

by Yoshiaki Iwase¹, Yoji Horie¹, Sawao Honda², Yusuke Daiko² and Yuji Iwamoto^2,*

¹ Applied Research Laboratory, General Center of Research and Development, Toagosei Co., Ltd., 8, Showa-cho, Minato-ku, Nagoya 455-0026, Japan

² Department of Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Materials 2018, 11(3), 422; https://doi.org/10.3390/ma11030422 - 13 Mar 2018

Cited by 8 | Viewed by 3798

Abstract

Polyalkoxysilsesquiazanes ([ROSi(NH)_1.5]_n, ROSZ, R = Et, nPr, iPr, nBu, sBu, nHex, sHex, cHex, decahydronaphthyl (DHNp)) were synthesized by ammonolysis at −78 °C of alkoxytrichlorosilane (ROSiCl₃), which was isolated by distillation as a reaction product of SiCl₄ [...] Read more.

Polyalkoxysilsesquiazanes ([ROSi(NH)_1.5]_n, ROSZ, R = Et, nPr, iPr, nBu, sBu, nHex, sHex, cHex, decahydronaphthyl (DHNp)) were synthesized by ammonolysis at −78 °C of alkoxytrichlorosilane (ROSiCl₃), which was isolated by distillation as a reaction product of SiCl₄ and ROH. The simultaneous thermogravimetric and mass spectrometry analyses of the ROSZs under helium revealed a common decomposition reaction, the cleavage of the oxygen–carbon bond of the RO group to evolve alkene as a main gaseous species formed in-situ, leading to the formation of microporous amorphous Si–O–N at 550 °C to 800 °C. The microporosity in terms of the peak of the pore size distribution curve located within the micropore size range (<2 nm) and the total micropore volume, as well as the specific surface area (SSA) of the Si–O–N, increased consistently with the molecular size estimated for the alkene formed in-situ during the pyrolysis. The CO₂ capture capacity at 0 °C of the Si–O–N material increased consistently with its SSA, and an excellent CO₂ capture capacity of 3.9 mmol·g⁻¹ at 0 °C and CO₂ 1 atm was achieved for the Si–O–N derived from DHNpOSZ having an SSA of 750 m²·g⁻¹. The CO₂ capture properties were further discussed based on their temperature dependency, and a surface functional group of the Si–O–N formed in-situ during the polymer/ceramics thermal conversion. Full article

(This article belongs to the Special Issue Polymer Derived Ceramics and Applications)

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11 pages, 6524 KiB

Open AccessArticle

Au Nanoparticle Sub-Monolayers Sandwiched between Sol-Gel Oxide Thin Films

by Enrico Della Gaspera¹, Enrico Menin², Gianluigi Maggioni³

, Cinzia Sada⁴ and Alessandro Martucci^2,5,*

¹ School of Science, RMIT University, Melbourne 3000, Australia

² Department of Industrial Engineering, University of Padova, via Marzolo 9, Padova 35131, Italy

³ Materials and Detectors Division, INFN, Legnaro National Laboratories, Viale dell’Università, Legnaro 35020, Italy

⁴ Department of Physiscs and Astronomy, University of Padova, via Marzolo 8, Padova 35131, Italy

⁵ National Research Council of Italy, Institute for Photonics and Nanotechnologies, Padova, via Trasea 7, Padova 35131, Italy

Materials 2018, 11(3), 423; https://doi.org/10.3390/ma11030423 - 14 Mar 2018

Cited by 1 | Viewed by 4314

Abstract

Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO₂, ZnO, and NiO. X-ray diffraction shows the crystallinity [...] Read more.

Sub-monolayers of monodisperse Au colloids with different surface coverage have been embedded in between two different metal oxide thin films, combining sol-gel depositions and proper substrates functionalization processes. The synthetized films were TiO₂, ZnO, and NiO. X-ray diffraction shows the crystallinity of all the oxides and verifies the nominal surface coverage of Au colloids. The surface plasmon resonance (SPR) of the metal nanoparticles is affected by both bottom and top oxides: in fact, the SPR peak of Au that is sandwiched between two different oxides is centered between the SPR frequencies of Au sub-monolayers covered with only one oxide, suggesting that Au colloids effectively lay in between the two oxide layers. The desired organization of Au nanoparticles and the morphological structure of the prepared multi-layered structures has been confirmed by Rutherford backscattering spectrometry (RBS), Secondary Ion Mass Spectrometry (SIMS), and Scanning Electron Microscopy (SEM) analyses that show a high quality sandwich structure. The multi-layered structures have been also tested as optical gas sensors. Full article

(This article belongs to the Special Issue Sol-Gel Chemistry Applied to Materials Science)

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12 pages, 1517 KiB

Open AccessArticle

Stepwise Thermo-Responsive Amino Acid-Derived Triblock Vinyl Polymers: ATRP Synthesis of Polymers, Aggregation, and Gelation Properties via Flower-Like Micelle Formation

by Nobuyuki Higashi^*, Sho Matsubara, Shin-nosuke Nishimura and Tomoyuki Koga^*

Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan

Materials 2018, 11(3), 424; https://doi.org/10.3390/ma11030424 - 15 Mar 2018

Cited by 16 | Viewed by 4960

Abstract

Novel thermo-responsive ABA-type triblock copolymers (poly(NAAMe_n-b-NAGMe₂₄₀-b-NAAMe_n), n = 18–72) composed of naturally occurring amino acid–based vinyl polymer blocks such as poly(N-acryloyl-l-alanine methyl ester (poly(NAAMe)) as the A segment and [...] Read more.

Novel thermo-responsive ABA-type triblock copolymers (poly(NAAMe_n-b-NAGMe₂₄₀-b-NAAMe_n), n = 18–72) composed of naturally occurring amino acid–based vinyl polymer blocks such as poly(N-acryloyl-l-alanine methyl ester (poly(NAAMe)) as the A segment and poly(N-acryloyl-glycine methylester)(poly(NAGMe)) as the B segment have been synthesized by the atom transfer radical polymerization (ATRP). Their thermal behaviors were analyzed in dilute aqueous solutions by turbidimetry. The turbidity curves provided two-step LCST transitions, and a flower-like micelle formation was confirmed at the temperature region between the first and second LCST transitions by dynamic light scattering, AFM and TEM. At higher copolymer concentrations, hydrogels were obtained at temperatures above the first LCST due to network formation induced with the flower-like micelles as cross-linker. The hydrogels were found to be switched to a sol state when cooled below the first LCST. These hydrogels also exhibited self-healable and injectable capabilities, which were evaluated by rheological measurements. Full article

(This article belongs to the Special Issue Temperature-Responsive Polymers)

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10 pages, 3812 KiB

Open AccessArticle

A Heat-Stimulated Luminous Fiber Using Heat-Sensitive Green TF-G Pigment

by Yang Jin, Xiaolong An and Mingqiao Ge^*

College of Textile and Clothing, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China

Materials 2018, 11(3), 425; https://doi.org/10.3390/ma11030425 - 15 Mar 2018

Cited by 10 | Viewed by 3882

Abstract

In this study, we fabricated a heat-stimulated luminous fiber (HSLF) by wet spinning. The HSLF consists of Sr₂ZnSi₂O₇: Eu²⁺, Dy³⁺ (SZSO), Y₂O₂S: Eu³⁺, Mg²⁺, Ti⁴⁺ [...] Read more.

In this study, we fabricated a heat-stimulated luminous fiber (HSLF) by wet spinning. The HSLF consists of Sr₂ZnSi₂O₇: Eu²⁺, Dy³⁺ (SZSO), Y₂O₂S: Eu³⁺, Mg²⁺, Ti⁴⁺ (YOS), and heat-sensitive green TF-G pigment (HSGP). SZSO and YOS serve as a source of luminescence to yield a long afterglow system. HSGP is a heat-stimulating agent which develops the link between luminescence and temperature for HSLF. The luminescence of the HSLF is dull below 30 °C, but vivid above 30 °C. The luminescence of HSLFs can be stimulated by low heat (human body temperature). Emission spectra were recorded at 20 °C and 30 °C to investigate the heat-stimulated luminescent performance of HSLFs. HSLF is a smart material which can discern the exciting light to change color because of the photo-thermal effect. This characteristic provides optimum conditions for SZSO and YOS to store energy. The results demonstrated that most luminescence from SZSO and YOS could be absorbed by HSGP at 20 °C, but the luminescence could be liberated at 30 °C. The heat-stimulated phenomenon could also be verified by afterglow and the naked eye. Full article

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19 pages, 2512 KiB

Open AccessArticle

Multi-Response Optimization of Resin Finishing by Using a Taguchi-Based Grey Relational Analysis

by Md. Nahid Pervez¹

, Faizan Shafiq¹, Zahid Sarwar², Muhammad Munib Jilani² and Yingjie Cai^1,*

¹ Hubei Provincial Engineering Laboratory for Clean Production and High Value Utilization of Bio-Based Textile Materials, Wuhan Textile University, Wuhan 430073, China

² Department of Textile Processing, National Textile University, Faisalabad 37610, Pakistan

Materials 2018, 11(3), 426; https://doi.org/10.3390/ma11030426 - 15 Mar 2018

Cited by 64 | Viewed by 5614

Abstract

In this study, the influence and optimization of the factors of a non-formaldehyde resin finishing process on cotton fabric using a Taguchi-based grey relational analysis were experimentally investigated. An L₂₇ orthogonal array was selected for five parameters and three levels by applying [...] Read more.

In this study, the influence and optimization of the factors of a non-formaldehyde resin finishing process on cotton fabric using a Taguchi-based grey relational analysis were experimentally investigated. An L₂₇ orthogonal array was selected for five parameters and three levels by applying Taguchi’s design of experiments. The Taguchi technique was coupled with a grey relational analysis to obtain a grey relational grade for evaluating multiple responses, i.e., crease recovery angle (CRA), tearing strength (TE), and whiteness index (WI). The optimum parameters (values) for resin finishing were the resin concentration (80 g·L⁻¹), the polyethylene softener (40 g·L⁻¹), the catalyst (25 g·L⁻¹), the curing temperature (140 °C), and the curing time (2 min). The goodness-of-fit of the data was validated by an analysis of variance (ANOVA). The optimized sample was characterized by Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscope (SEM) to better understand the structural details of the resin finishing process. The results showed an improved thermal stability and confirmed the presence of well deposited of resin on the optimized fabric surface. Full article

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13 pages, 2094 KiB

Open AccessArticle

Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation

by Hongjia Zhang¹, Tan Sui^1,2,†

, Enrico Salvati^1,†

, Dominik Daisenberger³, Alexander J. G. Lunt^1,4

, Kai Soon Fong⁵, Xu Song⁵

and Alexander M. Korsunsky^1,*

¹ Department of Engineering Science, University of Oxford, Oxford OX1 3PJ, UK

² Department of Mechanical Engineering Sciences, University of Surrey, Guildford GU2 7XH, UK

³ Beamline I15, Diamond Light Source, Didcot OX11 0DE, UK

⁴ CERN, CH-1211 Geneva 23, Switzerland

⁵ Singapore Institute of Manufacturing Technology (SIMTech), 73 Nanyang Drive, Singapore 637662, Singapore

^† These authors contributed equally to this work.

Materials 2018, 11(3), 427; https://doi.org/10.3390/ma11030427 - 15 Mar 2018

Cited by 11 | Viewed by 6141

Abstract

High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position [...] Read more.

High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ‘caking’ (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ‘caking’ with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation. Full article

(This article belongs to the Special Issue ICKEM2018 - Hierarchically Structured Materials (HSM))

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19 pages, 4553 KiB

Open AccessArticle

Artificial Intelligence Based Optimization for the Se(IV) Removal from Aqueous Solution by Reduced Graphene Oxide-Supported Nanoscale Zero-Valent Iron Composites

by Rensheng Cao¹, Mingyi Fan¹

, Jiwei Hu^1,2,*

, Wenqian Ruan¹, Xianliang Wu² and Xionghui Wei³

¹ Guizhou Provincial Key Laboratory for Information Systems of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang 550001, China

² Cultivation Base of Guizhou National Key Laboratory of Mountainous Karst Eco-environment, Guizhou Normal University, Guiyang 550001, China

³ Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China

Materials 2018, 11(3), 428; https://doi.org/10.3390/ma11030428 - 15 Mar 2018

Cited by 24 | Viewed by 4802

Abstract

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron [...] Read more.

Highly promising artificial intelligence tools, including neural network (ANN), genetic algorithm (GA) and particle swarm optimization (PSO), were applied in the present study to develop an approach for the evaluation of Se(IV) removal from aqueous solutions by reduced graphene oxide-supported nanoscale zero-valent iron (nZVI/rGO) composites. Both GA and PSO were used to optimize the parameters of ANN. The effect of operational parameters (i.e., initial pH, temperature, contact time and initial Se(IV) concentration) on the removal efficiency was examined using response surface methodology (RSM), which was also utilized to obtain a dataset for the ANN training. The ANN-GA model results (with a prediction error of 2.88%) showed a better agreement with the experimental data than the ANN-PSO model results (with a prediction error of 4.63%) and the RSM model results (with a prediction error of 5.56%), thus the ANN-GA model was an ideal choice for modeling and optimizing the Se(IV) removal by the nZVI/rGO composites due to its low prediction error. The analysis of the experimental data illustrates that the removal process of Se(IV) obeyed the Langmuir isotherm and the pseudo-second-order kinetic model. Furthermore, the Se 3d and 3p peaks found in XPS spectra for the nZVI/rGO composites after removing treatment illustrates that the removal of Se(IV) was mainly through the adsorption and reduction mechanisms. Full article

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12 pages, 8767 KiB

Open AccessArticle

Effect of Multiwalled Carbon Nanotubes on the Mechanical Properties of Carbon Fiber-Reinforced Polyamide-6/Polypropylene Composites for Lightweight Automotive Parts

by Huu-Duc Nguyen-Tran, Van-Tho Hoang

, Van-Ta Do, Doo-Man Chun

and Young-Jin Yum^*

School of Mechanical Engineering, University of Ulsan, Ulsan 44610, Korea

Materials 2018, 11(3), 429; https://doi.org/10.3390/ma11030429 - 15 Mar 2018

Cited by 80 | Viewed by 8295

Abstract

The development of lightweight automotive parts is an important issue for improving the efficiency of vehicles. Polymer composites have been widely applied to reduce weight and improve mechanical properties by mixing polymers with carbon fibers, glass fibers, and carbon nanotubes. Polypropylene (PP) has [...] Read more.

The development of lightweight automotive parts is an important issue for improving the efficiency of vehicles. Polymer composites have been widely applied to reduce weight and improve mechanical properties by mixing polymers with carbon fibers, glass fibers, and carbon nanotubes. Polypropylene (PP) has been added to carbon fiber-reinforced nylon-6 (CF/PA6) composite to achieve further weight reduction and water resistance. However, the mechanical properties were reduced by the addition of PP. In this research, multiwalled carbon nanotubes (CNTs) were added to compensate for the reduced mechanical properties experienced when adding PP. Tensile testing and bending tests were carried out to evaluate the mechanical properties. A small amount of CNTs improved the mechanical properties of carbon fiber-reinforced PA6/PP composites. For example, the density of CF/PA6 was reduced from 1.214 to 1.131 g/cm³ (6.8%) by adding 30 wt % PP, and the tensile strength of 30 wt % PP composite was improved from 168 to 173 MPa (3.0%) by adding 0.5 wt % CNTs with small increase of density (1.135 g/cm³). The developed composite will be widely used for lightweight automotive parts with improved mechanical properties. Full article

(This article belongs to the Section Advanced Composites)

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9 pages, 1737 KiB

Open AccessArticle

Two-Dimensional MX2 Semiconductors for Sub-5 nm Junctionless Field Effect Transistors

by Bin Peng^*, Wei Zheng, Jiantao Qin and Wanli Zhang

State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China

Materials 2018, 11(3), 430; https://doi.org/10.3390/ma11030430 - 15 Mar 2018

Cited by 6 | Viewed by 4209

Abstract

Two-dimensional transitional metal dichalcogenide (TMDC) field-effect transistors (FETs) are proposed to be promising for devices scaling beyond silicon-based devices. We explore the different effective mass and bandgap of the channel materials and figure out the possible candidates for high-performance devices with the gate [...] Read more.

Two-dimensional transitional metal dichalcogenide (TMDC) field-effect transistors (FETs) are proposed to be promising for devices scaling beyond silicon-based devices. We explore the different effective mass and bandgap of the channel materials and figure out the possible candidates for high-performance devices with the gate length at 5 nm and below by solving the quantum transport equation self-constantly with the Poisson equation. We find that out of the 14 compounds, MoS₂, MoSe₂, and MoTe₂ may be used in the devices to achieve a good subthreshold swing and a reasonable current ON-OFF ratio and delay. Our work points out the direction of further device optimization for experiments. Full article

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18 pages, 6535 KiB

Open AccessArticle

Optoelectronic Properties of X-Doped (X = O, S, Te) Photovoltaic CSe with Puckered Structure

by Qiang Zhang, Tianyuan Xin, Xiaoke Lu and Yuexia Wang^*

Applied Ion Beam Physics Laboratory, Institute of Modern Physics, Fudan University, Shanghai 200433, China

Materials 2018, 11(3), 431; https://doi.org/10.3390/ma11030431 - 16 Mar 2018

Cited by 17 | Viewed by 5116

Abstract

We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to [...] Read more.

We exploited novel two-dimensional (2D) carbon selenide (CSe) with a structure analogous to phosphorene, and probed its electronics and optoelectronics. Calculating phonon spectra using the density functional perturbation theory (DFPT) method indicated that 2D CSe possesses dynamic stability, which made it possible to tune and equip CSe with outstanding properties by way of X-doping (X = O, S, Te), i.e., X substituting Se atoms. Then systematic investigation on the structural, electronic, and optical properties of pristine and X-doped monolayer CSe was carried out using the density functional theory (DFT) method. It was found that the bonding feature of C-X is intimately associated with the electronegativity and radius of the doping atoms, which leads to diverse electronic and optical properties for doping different group VI elements. All the systems possess direct gaps, except for O-doping. Substituting O for Se atoms in monolayer CSe brings about a transition from a direct Γ-Γ band gap to an indirect Γ-Y band gap. Moreover, the value of the band gap decreases with increased doping concentration and radius of doping atoms. A red shift in absorption spectra occurs toward the visible range of radiation after doping, and the red-shift phenomenon becomes more obvious with increased radius and concentration of doping atoms. The results can be useful for filtering doping atoms according to their radius or electronegativity in order to tailor optical spectra efficiently. Full article

(This article belongs to the Special Issue Density Functional Theory (DFT) Calculation of Materials Properties)

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12 pages, 986 KiB

Open AccessArticle

Anisotropic-Cyclicgraphene: A New Two-Dimensional Semiconducting Carbon Allotrope

by Marcin Maździarz^1,*

, Adam Mrozek²

, Wacław Kuś³ and Tadeusz Burczyński¹

¹ Institute of Fundamental Technological Research Polish Academy of Sciences, Pawińskiego 5B, 02-106 Warsaw, Poland

² Department of Applied Computer Science and Modelling, AGH University of Science and Technology, Mickiewicza 30, 30-059 Cracow, Poland

³ Institute of Computational and Mechanical Engineering, Silesian University of Technology, Konarskiego 18A, 44-100 Gliwice, Poland

Materials 2018, 11(3), 432; https://doi.org/10.3390/ma11030432 - 16 Mar 2018

Cited by 14 | Viewed by 5330

Abstract

A potentially new, single-atom thick semiconducting 2D-graphene-like material, called Anisotropic-cyclicgraphene , has been generated by the two stage searching strategy linking molecular and ab initio approach. The candidate was derived from the evolutionary-based algorithm and molecular simulations was then profoundly analysed [...] Read more.

A potentially new, single-atom thick semiconducting 2D-graphene-like material, called Anisotropic-cyclicgraphene , has been generated by the two stage searching strategy linking molecular and ab initio approach. The candidate was derived from the evolutionary-based algorithm and molecular simulations was then profoundly analysed using first-principles density functional theory from the structural, mechanical, phonon, and electronic properties point of view. The proposed polymorph of graphene (rP16-P1m1) is mechanically, dynamically, and thermally stable and can achieve semiconducting with a direct band gap of 0.829 eV. Full article

(This article belongs to the Section Carbon Materials)

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13 pages, 15653 KiB

Open AccessArticle

Wear Behaviours and Oxidation Effects on Different UHMWPE Acetabular Cups Using a Hip Joint Simulator

by Saverio Affatato^1,*

, Alessandro Ruggiero²

, Sami Abdel Jaber¹, Massimiliano Merola² and Pierangiola Bracco³

¹ Medical Technology Laboratory, IRCCS—Rizzoli Orthopaedic Institute, Via di Barbiano, 1/10, 40136 Bologna, Italy

² Department of Industrial Engineering, University of Salerno, 84084 Fisciano, Italy

³ Chemistry Department and Nanostructured Interfaces and Surfaces (NIS) Centre, University of Turin, Via Giuria 7, 10125 Turin, Italy

Materials 2018, 11(3), 433; https://doi.org/10.3390/ma11030433 - 16 Mar 2018

Cited by 26 | Viewed by 4539

Abstract

Given the long-term problem of polyethylene wear, medical interest in the new improved cross-linked polyethylene (XLPE), with or without the adding of vitamin E, has risen. The main aim of this study is to gain further insights into the mutual effects of radiation [...] Read more.

Given the long-term problem of polyethylene wear, medical interest in the new improved cross-linked polyethylene (XLPE), with or without the adding of vitamin E, has risen. The main aim of this study is to gain further insights into the mutual effects of radiation cross-linking and addition of vitamin E on the wear performance of ultra-high-molecular-weight polyethylene (UHMWPE). We tested four different batches of polyethylene (namely, a standard one, a vitamin E-stabilized, and two cross-linked) in a hip joint simulator for five million cycles where bovine calf serum was used as lubricant. The acetabular cups were then analyzed using a confocal profilometer to characterize the surface topography. Moreover; the cups were analyzed by using Fourier Transformed Infrared Spectroscopy and Differential Scanning Calorimetry in order to assess the chemical characteristics of the pristine materials. Comparing the different cups’ configuration, mass loss was found to be higher for standard polyethylene than for the other combinations. Mass loss negatively correlated to the cross-link density of the polyethylenes. None of the tested formulations showed evidence of oxidative degradation. We found no correlation between roughness parameters and wear. Furthermore, we found significantly differences in the wear behavior of all the acetabular cups. XLPEs exhibited lower weight loss, which has potential for reduced wear and decreased osteolysis. However, surface topography revealed smoother surfaces of the standard and vitamin E stabilized polyethylene than on the cross-linked samples. This observation suggests incipient crack generations on the rough and scratched surfaces of the cross-linked polyethylene liners. Full article

(This article belongs to the Special Issue Advanced Biomaterials for Orthopaedic Application: The Challenge of New Composites and Alloys Used as Medical Devices)

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15 pages, 33472 KiB

Open AccessArticle

Hot Deformation Behavior and a Two-Stage Constitutive Model of 20Mn5 Solid Steel Ingot during Hot Compression

by Min Liu, Qing-Xian Ma^* and Jian-Bin Luo

Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

Materials 2018, 11(3), 434; https://doi.org/10.3390/ma11030434 - 16 Mar 2018

Cited by 4 | Viewed by 4384

Abstract

20Mn5 steel is widely used in the manufacture of heavy hydro-generator shaft forging due to its strength, toughness, and wear resistance. However, the hot deformation and recrystallization behaviors of 20Mn5 steel compressed under a high temperature were not studied. For this article, hot [...] Read more.

20Mn5 steel is widely used in the manufacture of heavy hydro-generator shaft forging due to its strength, toughness, and wear resistance. However, the hot deformation and recrystallization behaviors of 20Mn5 steel compressed under a high temperature were not studied. For this article, hot compression experiments under temperatures of 850–1200 °C and strain rates of 0.01 s⁻¹–1 s⁻¹ were conducted using a Gleeble-1500D thermo-mechanical simulator. Flow stress-strain curves and microstructure after hot compression were obtained. Effects of temperature and strain rate on microstructure are analyzed. Based on the classical stress-dislocation relationship and the kinetics of dynamic recrystallization, a two-stage constitutive model is developed to predict the flow stress of 20Mn5 steel. Comparisons between experimental flow stress and predicted flow stress show that the predicted flow stress values are in good agreement with the experimental flow stress values, which indicates that the proposed constitutive model is reliable and can be used for numerical simulation of hot forging of 20Mn5 solid steel ingot. Full article

(This article belongs to the Special Issue Materials: 10th Anniversary)

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15 pages, 48828 KiB

Open AccessArticle

Laser-Aided Directed Energy Deposition of Steel Powder over Flat Surfaces and Edges

by Fabrizia Caiazzo^*

and Vittorio Alfieri

Department of Industrial Engineering, University of Salerno, 84084 Fisciano, Italy

Materials 2018, 11(3), 435; https://doi.org/10.3390/ma11030435 - 16 Mar 2018

Cited by 23 | Viewed by 4972

Abstract

In the framework of Additive Manufacturing of metals, Directed Energy Deposition of steel powder over flat surfaces and edges has been investigated in this paper. The aims are the repair and overhaul of actual, worn-out, high price sensitive metal components. A full-factorial experimental [...] Read more.

In the framework of Additive Manufacturing of metals, Directed Energy Deposition of steel powder over flat surfaces and edges has been investigated in this paper. The aims are the repair and overhaul of actual, worn-out, high price sensitive metal components. A full-factorial experimental plan has been arranged, the results have been discussed in terms of geometry, microhardness and thermal affection as functions of the main governing parameters, laser power, scanning speed and mass flow rate; dilution and catching efficiency have been evaluated as well to compare quality and effectiveness of the process under conditions of both flat and edge depositions. Convincing results are presented to give grounds for shifting the process to actual applications: namely, no cracks or pores have been found in random cross-sections of the samples in the processing window. Interestingly an effect of the scanning conditions has been proven on the resulting hardness in the fusion zone; therefore, the mechanical characteristics are expected to depend on the processing parameters. Full article

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25 pages, 11752 KiB

Open AccessArticle

Investigation of Polyaniline and a Functionalised Derivative as Antimicrobial Additives to Create Contamination Resistant Surfaces

by Julia Robertson¹

, Marija Gizdavic-Nikolaidis² and Simon Swift^1,*

¹ Department of Molecular Medicine and Pathology, The University of Auckland, Auckland 1023, New Zealand

² School of Chemical Sciences, The University of Auckland, Auckland 1142, New Zealand

Materials 2018, 11(3), 436; https://doi.org/10.3390/ma11030436 - 16 Mar 2018

Cited by 20 | Viewed by 5014

Abstract

Antimicrobial surfaces can be applied to break transmission pathways in hospitals. Polyaniline (PANI) and poly(3-aminobenzoic acid) (P3ABA) are novel antimicrobial agents with potential as non-leaching additives to provide contamination resistant surfaces. The activity of PANI and P3ABA were investigated in suspension and as [...] Read more.

Antimicrobial surfaces can be applied to break transmission pathways in hospitals. Polyaniline (PANI) and poly(3-aminobenzoic acid) (P3ABA) are novel antimicrobial agents with potential as non-leaching additives to provide contamination resistant surfaces. The activity of PANI and P3ABA were investigated in suspension and as part of absorbent and non-absorbent surfaces. The effect of inoculum size and the presence of organic matter on surface activity was determined. PANI and P3ABA both demonstrated bactericidal activity against Escherichia coli and Staphylococcus aureus in suspension and as part of an absorbent surface. Only P3ABA showed antimicrobial activity in non-absorbent films. The results that are presented in this work support the use of P3ABA to create contamination resistant surfaces. Full article

(This article belongs to the Special Issue Conductive Polymers: Materials and Applications)

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12 pages, 7004 KiB

Open AccessArticle

Experimental Study on the Fire Performance of Tubular Steel Columns with Membrane Protections for Prefabricated and Modular Steel Construction

by Xin Zhang^1,2, Lei Peng³, Zhao-peng Ni³, Tian-xiao Ni², Yi-liang Huang³ and Yang Zhou^1,*

¹ School of Civil Engineering, Central South University, Changsha 410075, China

² Changsha Kerich Fire Protection Engineering Tech. CO., Ltd., Changsha 410007, China

³ Tianjin Fire Research Institute of the Ministry of Public Security, Tianjin 300381, China

Materials 2018, 11(3), 437; https://doi.org/10.3390/ma11030437 - 16 Mar 2018

Cited by 9 | Viewed by 6537

Abstract

Experimental research was conducted to study the fire resistance of steel tubular columns used in prefabricated and modular construction. In order to achieve high-efficient prefabrication and fast on-site installation, membrane protections using board products and thermal insulation blankets are adopted as the favorable [...] Read more.

Experimental research was conducted to study the fire resistance of steel tubular columns used in prefabricated and modular construction. In order to achieve high-efficient prefabrication and fast on-site installation, membrane protections using board products and thermal insulation blankets are adopted as the favorable protection method. Three protected tubular columns were tested in a full-scale column furnace with axial load applied. The study variables were different membranes, including fiber reinforced calcium silicate (FRCS) boards, rock wool and aluminum silica (Fiberfrax) insulations. The results suggest that one layer of 12 mm FRCS board with rock wool insulation has insufficient fire protection. However, steel columns protected with two layers of 12 mm FRCS boards with insulation appeared to have good fire resistances and could achieve a fire resistance rating as high as 2.5~3.0 h. Full article

(This article belongs to the Section Advanced Materials Characterization)

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15 pages, 2308 KiB

Open AccessArticle

Optical and Electrical Characterization of Biocompatible Polymeric Lines for Hemodialysis Applications

by Enrico Ravagli¹

and Stefano Severi^1,2,*

¹ Department of Electrical, Electronic and Information Engineering “Guglielmo Marconi”, University of Bologna, 47521 Cesena, Italy

² Health Sciences and Technologies-Interdepartmental Center for Industrial Research, University of Bologna, 47521 Cesena, Italy

Materials 2018, 11(3), 438; https://doi.org/10.3390/ma11030438 - 16 Mar 2018

Cited by 5 | Viewed by 5649

Abstract

During hemodialysis (HD), blood is circulated through an extracorporeal tubing system (bloodline) made of medical-grade polymeric material. Sensors of various types that do not come into contact with blood (optical, electromagnetic, etc.) are applied directly across the bloodline for clinical purposes and for [...] Read more.

During hemodialysis (HD), blood is circulated through an extracorporeal tubing system (bloodline) made of medical-grade polymeric material. Sensors of various types that do not come into contact with blood (optical, electromagnetic, etc.) are applied directly across the bloodline for clinical purposes and for therapy customization. Thus, a detailed knowledge of the bloodline’s physical properties is useful for the development of next-generation HD sensors. In this work, we performed a novel comparative analysis of the materials used by the manufacturers of the bloodlines. We focused on signals and characterization techniques matching those of the abovementioned sensors; consequently, this is an application-specific study of the optical and electrical characterization of bloodline material. Such properties are analyzed and compared for bloodlines from seven different manufacturers by optical absorbance spectroscopy and electrical impedance spectroscopy (EIS). Absorbance spectrum measurements are carried out in the VIS-NIR range. Absorbance spectra are pre-processed and data from both types of analyses are normalized with respect to sample thickness. Optical analysis shows that all bloodlines except one have similarly shaped spectra with slight quantitative differences. In all optical spectra, we find a decreasing trend of specific absorption from 0.14 mm⁻¹ at 400 nm to 0.06 mm⁻¹ at 1000 nm, with an absorption peak at 915 nm. In one case, a large absorption peak centered at ≃600 nm is found. Electrical analysis shows that all bloodlines have the electrical properties of a constant-phase element (CPE), with statistically significant differences in parameters’ values. Estimation of electrical CPE parameters for all bloodline returns a range of 0.942–0.957 for parameter n and a range of 12.41–16.64 for parameter Q₀’. In conclusion, we find that, although some statistically significant differences are present, bloodlines from a representative group of manufacturers share similar electrical and optical properties. Therefore, contactless sensing devices developed for HD will work on different bloodlines if a simple recalibration is performed. Full article

(This article belongs to the Special Issue Polymeric Materials for Medical Applications)

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20 pages, 6298 KiB

Open AccessArticle

Effect of Target Composition and Sputtering Deposition Parameters on the Functional Properties of Nitrogenized Ag-Permalloy Flexible Thin Films Deposited on Polymer Substrates

by Waheed Khan^*

, Qun Wang^* and Xin Jin

College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China

Materials 2018, 11(3), 439; https://doi.org/10.3390/ma11030439 - 17 Mar 2018

Cited by 18 | Viewed by 6130

Abstract

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C₁₀H₈O₄)_n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is [...] Read more.

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C₁₀H₈O₄)_n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni₈₁Fe₁₉ permalloy films. Two target compositions (Ni₇₆Fe₁₉Ag₅ and Ni₇₂Fe₁₈Ag₁₀) were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N₂ mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency. Full article

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24 pages, 5182 KiB

Open AccessFeature PaperArticle

Optical Aggregation of Gold Nanoparticles for SERS Detection of Proteins and Toxins in Liquid Environment: Towards Ultrasensitive and Selective Detection

by Antonino Foti^1,2,†, Cristiano D’Andrea^1,‡

, Valentina Villari¹

, Norberto Micali¹

, Maria Grazia Donato¹, Barbara Fazio¹, Onofrio M. Maragò¹, Raymond Gillibert³

, Marc Lamy de la Chapelle^3,4 and Pietro G. Gucciardi^1,*

¹ CNR-IPCF, Istituto per i Processi Chimico-Fisici, Viale F. Stagno D’Alcontres 37, I-98168 Messina, Italy

² Dottorato di Ricerca in Fisica, Università di Messina, Viale F. Stagno D’Alcontres 31, I-98166 Messina, Italy

³ Laboratoire CSPBAT, Université de Paris 13, Sorbonne Paris Cité, CNRS, 74 Rue Marcel-Cachin, F-93017 Bobigny, France

⁴ Institut des Molécules et Matériaux du Mans (IMMM-UMR CNRS 6283), Université du Mans, Avenue Olivier Messiaen, 72085 Le Mans, France

^† Now at LPICM, Ecole Polytechnique, CNRS, 91128 Palaiseau, France.

^‡ Now at CNR—Istituto di Fisica Applicata “Nello Carrara” (IFAC), I-50019 Sesto Fiorentino (FI), Italy.

Materials 2018, 11(3), 440; https://doi.org/10.3390/ma11030440 - 17 Mar 2018

Cited by 54 | Viewed by 8311

Abstract

Optical forces are used to aggregate plasmonic nanoparticles and create SERS–active hot spots in liquid. When biomolecules are added to the nanoparticles, high sensitivity SERS detection can be accomplished. Here, we pursue studies on Bovine Serum Albumin (BSA) detection, investigating the BSA–nanorod aggregations [...] Read more.

Optical forces are used to aggregate plasmonic nanoparticles and create SERS–active hot spots in liquid. When biomolecules are added to the nanoparticles, high sensitivity SERS detection can be accomplished. Here, we pursue studies on Bovine Serum Albumin (BSA) detection, investigating the BSA–nanorod aggregations in a range from 100 µM to 50 nM by combining light scattering, plasmon resonance and SERS, and correlating the SERS signal with the concentration. Experimental data are fitted with a simple model describing the optical aggregation process. We show that BSA–nanorod complexes can be optically printed on non-functionalized glass surfaces, designing custom patterns stable with time. Furthermore, we demonstrate that this methodology can be used to detect catalase and hemoglobin, two Raman resonant biomolecules, at concentrations of 10 nM and 1 pM, respectively, i.e., well beyond the limit of detection of BSA. Finally, we show that nanorods functionalized with specific aptamers can be used to capture and detect Ochratoxin A, a fungal toxin found in food commodities and wine. This experiment represents the first step towards the addition of molecular specificity to this novel biosensor strategy. Full article

(This article belongs to the Special Issue SERS-Active Substrates)

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23 pages, 10645 KiB

Open AccessArticle

Modelling and Optimization of Polycaprolactone Ultrafine-Fibres Electrospinning Process Using Response Surface Methodology

by Adhi Anindyajati^*

, Philip Boughton

and Andrew J. Ruys

School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia

Materials 2018, 11(3), 441; https://doi.org/10.3390/ma11030441 - 17 Mar 2018

Cited by 20 | Viewed by 4756

Abstract

Electrospun fibres have gained broad interest in biomedical applications, including tissue engineering scaffolds, due to their potential in mimicking extracellular matrix and producing structures favourable for cell and tissue growth. The development of scaffolds often involves multivariate production parameters and multiple output characteristics [...] Read more.

Electrospun fibres have gained broad interest in biomedical applications, including tissue engineering scaffolds, due to their potential in mimicking extracellular matrix and producing structures favourable for cell and tissue growth. The development of scaffolds often involves multivariate production parameters and multiple output characteristics to define product quality. In this study on electrospinning of polycaprolactone (PCL), response surface methodology (RSM) was applied to investigate the determining parameters and find optimal settings to achieve the desired properties of fibrous scaffold for acetabular labrum implant. The results showed that solution concentration influenced fibre diameter, while elastic modulus was determined by solution concentration, flow rate, temperature, collector rotation speed, and interaction between concentration and temperature. Relationships between these variables and outputs were modelled, followed by an optimization procedure. Using the optimized setting (solution concentration of 10% w/v, flow rate of 4.5 mL/h, temperature of 45 °C, and collector rotation speed of 1500 RPM), a target elastic modulus of 25 MPa could be achieved at a minimum possible fibre diameter (1.39 ± 0.20 µm). This work demonstrated that multivariate factors of production parameters and multiple responses can be investigated, modelled, and optimized using RSM. Full article

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12 pages, 3891 KiB

Open AccessArticle

Poly(vinylidene Fluoride-Hexafluoropropylene) Porous Membrane with Controllable Structure and Applications in Efficient Oil/Water Separation

by Xinya Wang

, Changfa Xiao^*, Hailiang Liu, Qinglin Huang, Junqiang Hao and Hao Fu

State Key Laboratory of Separation Membranes and Membrane Processes, National Center for International Joint Research on Separation Membranes, Tianjin Polytechnic University, No. 399, Binshui Road, Xiqing District, Tianjin 300387, China

Materials 2018, 11(3), 443; https://doi.org/10.3390/ma11030443 - 18 Mar 2018

Cited by 46 | Viewed by 7111

Abstract

Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) porous membranes are fabricated via thermally induced phase separation (TIPS) with mixed diluent (dibutyl phthalate (DBP)/dioctyl phthalate (DOP)). The effects of mixed diluent are discussed in detail in term of morphology, mean pore size, selective wettability, etc. The results show [...] Read more.

Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) porous membranes are fabricated via thermally induced phase separation (TIPS) with mixed diluent (dibutyl phthalate (DBP)/dioctyl phthalate (DOP)). The effects of mixed diluent are discussed in detail in term of morphology, mean pore size, selective wettability, etc. The results show that the membrane structure changes from spherulitic to bicontinuous with the change of DBP/DOP ratio. It is also found that the degree of crystallization decreases with the decrease of DBP/DOP ratio in mixed diluent. When liquid–liquid (L-L) phase separation precedes solid–liquid (S-L) phase separation, the obtained membranes have outstanding hydrophobicity and lipophilicity, excellent mechanical property. Additionally, the PVDF-HFP hybrid membranes are prepared with silica (SiO₂) particles and the effect of SiO₂ content on structure and properties is discussed. It is found that the PVDF-HFP hybrid membrane with 2 wt % SiO₂ (M3-S2) has better properties and higher filtration rate and separation efficiency for surfactant-stabilized water-in-oil emulsion separation. Moreover, the membrane M3-S2 also exhibits excellent antifouling performance for long-running. Full article

(This article belongs to the Section Thin Films and Interfaces)

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11 pages, 3229 KiB

Open AccessArticle

Laser Direct Metal Deposition of 2024 Al Alloy: Trace Geometry Prediction via Machine Learning

by Fabrizia Caiazzo¹

and Alessandra Caggiano^2,3,*

¹ Department of Industrial Engineering, University of Salerno, 84084 Fisciano (SA), Italy

² Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy

³ Fraunhofer Joint Laboratory of Excellence on Advanced Production Technology (Fh-J_LEAPT UniNaples), 80125 Naples, Italy

Materials 2018, 11(3), 444; https://doi.org/10.3390/ma11030444 - 19 Mar 2018

Cited by 155 | Viewed by 10871

Abstract

Laser direct metal deposition is an advanced additive manufacturing technology suitably applicable in maintenance, repair, and overhaul of high-cost products, allowing for minimal distortion of the workpiece, reduced heat affected zones, and superior surface quality. Special interest is growing for the repair and [...] Read more.

Laser direct metal deposition is an advanced additive manufacturing technology suitably applicable in maintenance, repair, and overhaul of high-cost products, allowing for minimal distortion of the workpiece, reduced heat affected zones, and superior surface quality. Special interest is growing for the repair and coating of 2024 aluminum alloy parts, extensively utilized for a wide range of applications in the automotive, military, and aerospace sectors due to its excellent plasticity, corrosion resistance, electric conductivity, and strength-to-weight ratio. A critical issue in the laser direct metal deposition process is related to the geometrical parameters of the cross-section of the deposited metal trace that should be controlled to meet the part specifications. In this research, a machine learning approach based on artificial neural networks is developed to find the correlation between the laser metal deposition process parameters and the output geometrical parameters of the deposited metal trace produced by laser direct metal deposition on 5-mm-thick 2024 aluminum alloy plates. The results show that the neural network-based machine learning paradigm is able to accurately estimate the appropriate process parameters required to obtain a specified geometry for the deposited metal trace. Full article

(This article belongs to the Section Manufacturing Processes and Systems)

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9 pages, 1792 KiB

Open AccessArticle

Light Trapping with Silicon Light Funnel Arrays

by Ashish Prajapati¹

, Yuval Nissan¹, Tamir Gabay¹ and Gil Shalev^1,2,*

¹ Department of Electrical and Computer Engineering, Ben-Gurion University of the Negev, POB 653, Beer-Sheva 8410501, Israel

² The Ilse-Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, POB 653, Beer-Sheva 8410501, Israel

Materials 2018, 11(3), 445; https://doi.org/10.3390/ma11030445 - 19 Mar 2018

Cited by 14 | Viewed by 5633

Abstract

Silicon light funnels are three-dimensional subwavelength structures in the shape of inverted cones with respect to the incoming illumination. Light funnel (LF) arrays can serve as efficient absorbing layers on account of their light trapping capabilities, which are associated with the presence of [...] Read more.

Silicon light funnels are three-dimensional subwavelength structures in the shape of inverted cones with respect to the incoming illumination. Light funnel (LF) arrays can serve as efficient absorbing layers on account of their light trapping capabilities, which are associated with the presence of high-density complex Mie modes. Specifically, light funnel arrays exhibit broadband absorption enhancement of the solar spectrum. In the current study, we numerically explore the optical coupling between surface light funnel arrays and the underlying substrates. We show that the absorption in the LF array-substrate complex is higher than the absorption in LF arrays of the same height (~10% increase). This, we suggest, implies that a LF array serves as an efficient surface element that imparts additional momentum components to the impinging illumination, and hence optically excites the substrate by near-field light concentration, excitation of traveling guided modes in the substrate, and mode hybridization. Full article

(This article belongs to the Special Issue Latest Nanotechnology Research Output 2017—Select papers from Applied Nanotechnology and Nanoscience International Conference—ANNIC 2017)

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14 pages, 5956 KiB

Open AccessArticle

Facile Fabrication of Cu₂O Nanobelts in Ethanol on Nanoporous Cu and Their Photodegradation of Methyl Orange

by Zhenhua Dan^1,2,*

, Yulin Yang¹, Fengxiang Qin^3,*, Hao Wang⁴ and Hui Chang^1,2

¹ Tech Institute for Advanced Materials and College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China

² The Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing 210009, China

³ School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

⁴ Institute for Materials Research, Tohoku University, Sendai 9808577, Japan

Materials 2018, 11(3), 446; https://doi.org/10.3390/ma11030446 - 19 Mar 2018

Cited by 79 | Viewed by 6673

Abstract

Thin cupric oxide (Cu₂O) nanobelts with width of few tens of nanometers to few hundreds of nanometers were fabricated in anhydrous ethanol on nanoporous copper templates that was prepared via dealloying amorphous Ti₄₀Cu₆₀ ribbons in hydrofluoric acid solutions [...] Read more.

Thin cupric oxide (Cu₂O) nanobelts with width of few tens of nanometers to few hundreds of nanometers were fabricated in anhydrous ethanol on nanoporous copper templates that was prepared via dealloying amorphous Ti₄₀Cu₆₀ ribbons in hydrofluoric acid solutions at 348 K. The Cu₂O octahedral particles preferentially form in the water, and nanobelts readily undergo the growth along the lengthwise and widthwise in the anhydrous ethanol. The ethanol molecules serve as stabilizing or capping reagents, and play a key role of the formation of two-dimensional Cu₂O nanobelts. Cu atoms at weak sites (i.e., twin boundary) on the nanoporous Cu ligaments are ionized to form Cu²⁺ cations, and then react with OH⁻ to form Cu₂O and H₂O. The two-dimensional growth of Cu₂O nanostructure is preferred in anhydrous ethanol due to the suppression of random growth of Cu₂O nanoarchitectures by ethanol. Cu₂O nanobelts have superior photodegradation performance of methyl orange, three times higher than nanoporous Cu. Full article

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10 pages, 5367 KiB

Open AccessArticle

Bismuth Oxysulfide and Its Polymer Nanocomposites for Efficient Purification

by Yidong Luo, Lina Qiao, Huanchun Wang, Shun Lan, Yang Shen, Yuanhua Lin^* and Cewen Nan

State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

Materials 2018, 11(3), 447; https://doi.org/10.3390/ma11030447 - 19 Mar 2018

Cited by 3 | Viewed by 4571

Abstract

The danger of toxic organic pollutants in both aquatic and air environments calls for high-efficiency purification material. Herein, layered bismuth copper oxychalcogenides, BiCuSO, nanosheets of high photocatalytic activity were introduced to the PVDF (Polyvinylidene Fluoride). The fibrous membranes provide an easy, efficient, and [...] Read more.

The danger of toxic organic pollutants in both aquatic and air environments calls for high-efficiency purification material. Herein, layered bismuth copper oxychalcogenides, BiCuSO, nanosheets of high photocatalytic activity were introduced to the PVDF (Polyvinylidene Fluoride). The fibrous membranes provide an easy, efficient, and recyclable way to purify organic pollutant. The physical and photophysical properties of the BiCuSO and its polymer composite were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), electron spin resonance (EPR). Photocatalysis of Congo Red reveals that the BiCuSO/PVDF shows a superior photocatalytic activity of a 55% degradation rate in 70 min at visible light. The high photocatalytic activity is attributed to the exposed active {101} facets and the triple vacant associates

V_{B i}^{‴} V_{O}^{• •} V_{B i}^{‴}

. By engineering the intrinsic defects on the surface of bismuth oxysulfide, high solar-driven photocatalytic activity can be approached. The successful fabrication of the bismuth oxysulfide and its polymer nanocomposites provides an easy and general approach for high-performance purification materials for various applications. Full article

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12 pages, 2290 KiB

Open AccessArticle

Electronic, Optical, and Lattice Dynamical Properties of Tetracalcium Trialuminate (Ca₄Al₆O₁₃)

by Huayue Mei, Yuhan Zhong, Peida Wang, Zhenyuan Jia, Chunmei Li

and Nanpu Cheng^*

Faculty of Materials and Energy, Southwest University, 2^#Tiansheng Road, Beibei, Chongqing 400715, China

Materials 2018, 11(3), 449; https://doi.org/10.3390/ma11030449 - 19 Mar 2018

Cited by 11 | Viewed by 4908

Abstract

The electronic, optical, and lattice dynamical properties of tetracalcium trialuminate (Ca₄Al₆O₁₃) with a special sodalite cage structure were calculated based on the density functional theory. Theoretical results show that Ca₄Al₆O₁₃ is ductile [...] Read more.

The electronic, optical, and lattice dynamical properties of tetracalcium trialuminate (Ca₄Al₆O₁₃) with a special sodalite cage structure were calculated based on the density functional theory. Theoretical results show that Ca₄Al₆O₁₃ is ductile and weakly anisotropic. The calculated Young’s modulus and Poisson ratio are 34.18 GPa and 0.32, respectively. Ca₄Al₆O₁₃ is an indirect-gap semiconductor with a band gap of 5.41 eV. The top of the valence band derives from O 2p states, and the bottom of conduction band consists of Ca 3d states. Transitions from O 2p, 2s states to empty Ca 4s, 3d and Al 3s, 3p states constitute the major peaks of the imaginary part of the dielectric function. Ca₄Al₆O₁₃ is a good UV absorber for photoelectric devices due to the high absorption coefficient and low reflectivity. The lattice vibration analysis reveals that O atoms contribute to the high-frequency portions of the phonon spectra, while Ca and Al atoms make important contributions to the middle- and low-frequency portions. At the center of the first Brillouin zone, lattice vibrations include the Raman active modes (E, A₁), infrared active mode (T₂), and silentmodes (T₁, A₂). Typical atomic displacement patterns were also investigated to understand the vibration modes more intuitively. Full article

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12 pages, 3844 KiB

Open AccessArticle

The Preparation of TiO₂ Film by the Sol-Gel Method and Evaluation of Its Self-Cleaning Property

by Yu Liang^1,2

, Sijia Sun¹, Tongrong Deng¹, Hao Ding^1,*, Wanting Chen¹ and Ying Chen¹

¹ Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences (Beijing), Beijing 100083, China

² School of Materials Science and Technology, Shenyang University of Chemical Technology, Shenyang 110142, China

Materials 2018, 11(3), 450; https://doi.org/10.3390/ma11030450 - 19 Mar 2018

Cited by 77 | Viewed by 8278

Abstract

TiO₂ sol was produced by the sol-gel method through the hydrolysis and the aging of tetrabutyl titanate and the TiO₂ film was obtained by dipping and uniform lifting of the acid-treated and ultrasound-treated clean glass slides into the TiO₂ sol [...] Read more.

TiO₂ sol was produced by the sol-gel method through the hydrolysis and the aging of tetrabutyl titanate and the TiO₂ film was obtained by dipping and uniform lifting of the acid-treated and ultrasound-treated clean glass slides into the TiO₂ sol followed by aging, drying, and calcination. The effect of the hydrolysis control agents to the formed sol was researched and the crystalline state, the morphology, and the photocatalytic properties of the products after calcination were characterized. The structural morphology, the contact angles before and after illumination, and the self-cleaning properties of the TiO₂ film were characterized as well. The results showed that by using acetylacetone as the hydrolysis control agent, the formed TiO₂ sol had relatively high stability. The product after the calcination of the TiO₂ sol was of single anatase type with crystalline size of 18–20 nm and it could degrade nearly 100% of methylene blue after 90 min illumination. The formed TiO₂ film is compact, continuous, smooth, and had the properties of super-hydrophilicity (after 30 min illumination due to its contact angle decreasing from 21° to nearly 0°) and anti-fogging capability, which indicated its excellent self-cleaning property. Full article

(This article belongs to the Special Issue Photocatalytic Materials for Energy and Environmental Applications)

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12 pages, 8354 KiB

Open AccessArticle

The Effect of Poly (Glycerol Sebacate) Incorporation within Hybrid Chitin–Lignin Sol–Gel Nanofibrous Scaffolds

by Turdimuhammad Abdullah^1,2, Lassaad Gzara³, Giovanna Simonetti⁴, Ahmed Alshahrie¹, Numan Salah¹, Pierfrancesco Morganti^5,6, Angelo Chianese⁷, Afsoon Fallahi⁸, Ali Tamayol⁹, Sidi A. Bencherif^8,10,11,12

and Adnan Memic^1,*

¹ Center of Nanotechnology, King Abdul Aziz University, Jeddah 21589, Saudi Arabia

² Department of Chemical and Materials Engineering, Faculty of Engineering, King Abdul Aziz University, Jeddah 21589, Saudi Arabia

³ Center of Excellence in Desalination Technology, King Abdul Aziz University, Jeddah 21589, Saudi Arabia

⁴ Department of Public Health and Infectious Diseases, “Sapienza” University of Rome, 00185 Rome, Italy

⁵ Department Mental/Physical Health and Preventive Medicine, Campania University, L.Vanvitelli, 80121 Naples, Italy

⁶ Nanoscience Centre MAVI, 04011 Aprilia, Italy

⁷ Chemical, Materials, Environmental Engineering Department, “Sapienza” University of Rome, 00185 Rome, Italy

⁸ Department of Chemical Engineering, Northeastern University, Boston, MA 02115, USA

⁹ Department of Mechanical & Materials Engineering, University of Nebraska, Lincoln, NE 68588, USA

¹⁰ Department of Bioengineering, Northeastern University, Boston, MA 02115, USA

¹¹ Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA

¹² UMR CNRS 7338 Biomechanics and Bioengineering, University of Technology of Compiègne, Sorbonne University, 60200 Compiègne, France

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Materials 2018, 11(3), 451; https://doi.org/10.3390/ma11030451 - 19 Mar 2018

Cited by 21 | Viewed by 7027

Abstract

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate [...] Read more.

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate their industrial utilization. In this paper, we fabricated hybrid fibers composed of a chitin–lignin (CL)-based sol–gel mixture and elastomeric poly (glycerol sebacate) (PGS) using a standard electrospinning approach. Obtained results showed that PGS could be coherently blended with the sol–gel mixture to form a nanofibrous scaffold exhibiting remarkable mechanical performance and improved antibacterial and antifungal activity. The developed hybrid fibers showed promising potential in advanced biomedical applications such as wound care products. Ultimately, recycling these sustainable biopolymers and other bio-wastes alike could propel a “greener” economy. Full article

(This article belongs to the Special Issue Polymeric Materials for Medical Applications)

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18 pages, 5847 KiB

Open AccessArticle

Gradient Nanostructured Tantalum by Thermal-Mechanical Ultrasonic Impact Energy

by Jong-Min Chae¹, Keun-Oh Lee¹ and Auezhan Amanov^2,*

¹ Department of Safety Engineering, Seoul National University of Science and Technology, Seoul 01811, Korea

² Department of Mechanical Engineering, Sun Moon University, Asan 31460, Korea

Materials 2018, 11(3), 452; https://doi.org/10.3390/ma11030452 - 20 Mar 2018

Cited by 20 | Viewed by 5770

Abstract

Microstructural evolution and wear performance of Tantalum (Ta) treated by ultrasonic nanocrystalline surface modification (UNSM) at 25 and 1000 °C were reported. The UNSM treatment modified a surface along with subsurface layer with a thickness in the range of 20 to 150 µm, [...] Read more.

Microstructural evolution and wear performance of Tantalum (Ta) treated by ultrasonic nanocrystalline surface modification (UNSM) at 25 and 1000 °C were reported. The UNSM treatment modified a surface along with subsurface layer with a thickness in the range of 20 to 150 µm, which depends on the UNSM treatment temperature, via the surface severe plastic deformation (S²PD) method. The cross-sectional microstructure of the specimens was observed by electron backscattered diffraction (EBSD) in order to confirm the microstructural alteration in terms of effective depth and refined grain size. The surface hardness measurement results, including depth profile, revealed that the hardness of the UNSM-treated specimens at both temperatures was increased in comparison with those of the untreated ones. The increase in UNSM treatment temperature led to a further increase in hardness. Moreover, both the UNSM-treated specimens with an increased hardness resulted in a higher resistance to wear in comparison with those of the untreated ones under dry conditions. The increase in hardness and induced compressive residual stress that depend on the formation of severe plastically deformed layer with the refined nano-grains are responsible for the enhancement in wear resistance. The findings of this study may be implemented in response to various industries that are related to strength improvement and wear enhancement issues of Ta. Full article

(This article belongs to the Special Issue Surface Modification to Improve Properties of Materials)

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27 pages, 21464 KiB

Open AccessArticle

Wastes as Aggregates, Binders or Additions in Mortars: Selecting Their Role Based on Characterization

by Catarina Brazão Farinha^1,2

, Jorge De Brito^1,*

, Rosário Veiga²

, J. M. Fernández³

, J. R. Jiménez⁴

and A. R. Esquinas³

¹ CERIS, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1-1049-001 Lisbon, Portugal

² National Laboratory for Civil Engineering, Av. do Brasil 101, 1700-066 Lisbon, Portugal

³ Inorganic Chemical Area, School of Engineering Sciences of Belmez, University of Córdoba, Av. de la Universidad s/n, 14240 Belmez, Spain

⁴ Construction Engineering Area, School of Engineering Sciences of Belmez, University of Córdoba, Av. de la Universidad s/n, 14240 Belmez, Spain

Materials 2018, 11(3), 453; https://doi.org/10.3390/ma11030453 - 20 Mar 2018

Cited by 21 | Viewed by 4925

Abstract

The production of waste has increased over the years and, lacking a recycle or recovery solution, it is forwarded to landfill. The incorporation of wastes in cement-based materials is a solution to reduce waste deposition. In this regard, some researchers have been studying [...] Read more.

The production of waste has increased over the years and, lacking a recycle or recovery solution, it is forwarded to landfill. The incorporation of wastes in cement-based materials is a solution to reduce waste deposition. In this regard, some researchers have been studying the incorporation of wastes with different functions: aggregate, binder and addition. The incorporation of wastes should take advantage of their characteristics. It requires a judicious analysis of their particles. This research involves the analysis of seven industrial wastes: biomass ashes, glass fibre, reinforced polymer dust, sanitary ware, fluid catalytic cracking, acrylic fibre, textile fibre and glass fibre. The main characteristics and advantages of each waste are enunciated and the best type of introduction in mortars is discussed. The characterization of the wastes as particles is necessary to identify the most suitable incorporation in mortars. In this research, some wastes are studied with a view to their re-use or recycling in mortars. Thus, this research focuses on the chemical, physical and mechanical characterization of industrial wastes and identification of the potentially most advantageous type of incorporation. Full article

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22 pages, 20226 KiB

Open AccessArticle

3D Printability of Alginate-Carboxymethyl Cellulose Hydrogel

by Ahasan Habib¹, Venkatachalem Sathish², Sanku Mallik² and Bashir Khoda^1,*

¹ Industrial and Manufacturing Engineering Department, North Dakota State University, Fargo, ND 58102, USA

² Pharmaceutical Sciences Department, North Dakota State University, Fargo, ND 58102, USA

Materials 2018, 11(3), 454; https://doi.org/10.3390/ma11030454 - 20 Mar 2018

Cited by 274 | Viewed by 21456

Abstract

Three-dimensional (3D) bio-printing is a revolutionary technology to reproduce a 3D functional living tissue scaffold in-vitro through controlled layer-by-layer deposition of biomaterials along with high precision positioning of cells. Due to its bio-compatibility, natural hydrogels are commonly considered as the scaffold material. However, [...] Read more.

Three-dimensional (3D) bio-printing is a revolutionary technology to reproduce a 3D functional living tissue scaffold in-vitro through controlled layer-by-layer deposition of biomaterials along with high precision positioning of cells. Due to its bio-compatibility, natural hydrogels are commonly considered as the scaffold material. However, the mechanical integrity of a hydrogel material, especially in 3D scaffold architecture, is an issue. In this research, a novel hybrid hydrogel, that is, sodium alginate with carboxymethyl cellulose (CMC) is developed and systematic quantitative characterization tests are conducted to validate its printability, shape fidelity and cell viability. The outcome of the rheological and mechanical test, filament collapse and fusion test demonstrate the favorable shape fidelity. Three-dimensional scaffold structures are fabricated with the pancreatic cancer cell, BxPC3 and the 86% cell viability is recorded after 23 days. This hybrid hydrogel can be a potential biomaterial in 3D bioprinting process and the outlined characterization techniques open an avenue directing reproducible printability and shape fidelity. Full article

(This article belongs to the Special Issue NextGen Materials for 3D Printing)

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15 pages, 10346 KiB

Open AccessArticle

Fabrication and Characteristics of Sintered Cutting Stainless Steel Fiber Felt with Internal Channels and an Al₂O₃ Coating

by Shufeng Huang^1,2, Zhenping Wan^1,* and Shuiping Zou¹

¹ School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China

² Department of Mechanical Engineering, University of South Carolina, Columbia, SC 2910, USA

Materials 2018, 11(3), 455; https://doi.org/10.3390/ma11030455 - 20 Mar 2018

Cited by 2 | Viewed by 5107

Abstract

A novel sintered cutting stainless steel fiber felt with internal channels (SCSSFFC) composed of a stainless-steel fiber skeleton, three-dimensional interconnected porous structure and multiple circular microchannels is developed. SCSSFFC has a jagged and rough surface morphology and possesses a high specific surface area, [...] Read more.

A novel sintered cutting stainless steel fiber felt with internal channels (SCSSFFC) composed of a stainless-steel fiber skeleton, three-dimensional interconnected porous structure and multiple circular microchannels is developed. SCSSFFC has a jagged and rough surface morphology and possesses a high specific surface area, which is approximately 2.4 times larger than that of the sintered bundle-drawing stainless steel fiber felt with internal channels (SBDSSFFC) and is expected to enhance adhesive strength. The sol-gel and wet impregnation methods are adopted to prepare SCSSFFC with an Al₂O₃ coating (SCSSFFC/Al₂O₃). The adhesive strength of SCSSFFC/Al₂O₃ is investigated using ultrasonic vibration and thermal shock tests. The experimental results indicate that the weight loss rate of the Al₂O₃ coating has a 4.2% and 8.42% reduction compared with those of SBDSSFFCs based on ultrasonic vibration and thermal shock tests. In addition, the permeability of SCSSFFC/Al₂O₃ is investigated based on forced liquid flow tests. The experimental results show that the permeability and inertial coefficients of SCSSFFC/Al₂O₃ are mainly affected by the coating rate, porosity and open ratio; however, the internal microchannel diameter has little influence. It is also found that SCSSFFC/Al₂O₃ yields superior permeability, as well as inertial coefficients compared with those of other porous materials reported in the literature. Full article

(This article belongs to the Section Porous Materials)

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10 pages, 11682 KiB

Open AccessArticle

Study on Microstructure and Mechanical Properties of Hypereutectic Al–18Si Alloy Modified with Al–3B

by Chunjie Gong^1,2,3, Hao Tu^1,2,3, Changjun Wu^1,2,3

, Jianhua Wang^1,2,3,*

and Xuping Su^1,2,3

¹ Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China

² Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, China

³ National Experimental Teaching Demonstration Center of Material Science and Engineering, Changzhou University, Changzhou 213164, China

Materials 2018, 11(3), 456; https://doi.org/10.3390/ma11030456 - 20 Mar 2018

Cited by 31 | Viewed by 4633

Abstract

An hypereutectic Al–18Si alloy was modified via an Al–3B master alloy. The effect of the added Al–3B and the modification temperature on the microstructure, tensile fracture morphologies, and mechanical properties of the alloy were investigated using an optical microscope, Image–Pro Plus 6.0, a [...] Read more.

An hypereutectic Al–18Si alloy was modified via an Al–3B master alloy. The effect of the added Al–3B and the modification temperature on the microstructure, tensile fracture morphologies, and mechanical properties of the alloy were investigated using an optical microscope, Image–Pro Plus 6.0, a scanning electron microscope, and a universal testing machine. The results show that the size of the primary Si and its fraction decreased at first, and then increased as an additional amount of Al–3B was added. When the added Al–3B reached 0.2 wt %, the fraction of the primary Si in the Al–18Si alloy decreased with an increase in temperature. Compared with the unmodified Al–18Si alloy, the tensile strength and elongation of the alloy modified at 850 °C with 0.2 wt % Al–3B increased by 25% and 81%, respectively. The tensile fracture of the modified Al–18Si alloy exhibited partial ductile fracture characteristics, but there were more areas with ductile characteristics compared with that of the unmodified Al–18Si alloy. Full article

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9 pages, 4554 KiB

Open AccessArticle

Evaluation of Fracture Strength of Ceramics Containing Small Surface Defects Introduced by Focused Ion Beam

by Nanako Sato¹ and Koji Takahashi^2,*

¹ Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan

² Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501, Japan

Materials 2018, 11(3), 457; https://doi.org/10.3390/ma11030457 - 20 Mar 2018

Cited by 19 | Viewed by 4933

Abstract

The aim of this study was to clarify the effects of micro surface defects introduced by the focused ion beam (FIB) technique on the fracture strength of ceramics. Three-point bending tests on alumina-silicon carbide (Al₂O₃/SiC) ceramic composites containing crack-like [...] Read more.

The aim of this study was to clarify the effects of micro surface defects introduced by the focused ion beam (FIB) technique on the fracture strength of ceramics. Three-point bending tests on alumina-silicon carbide (Al₂O₃/SiC) ceramic composites containing crack-like surface defects introduced by FIB were carried out. A surface defect with

\sqrt{a r e a}

in the range 19 to 35 µm was introduced at the center of each specimen. Test results showed that the fracture strengths of the FIB-defect specimens depended on

\sqrt{a r e a}

. The test results were evaluated using the evaluation equation of fracture strength based on the process zone size failure criterion and the

\sqrt{a r e a}

parameter model. The experimental results indicate that FIB-induced defects can be used as small initial cracks for the fracture strength evaluation of ceramics. Moreover, the proposed equation was useful for the fracture strength evaluation of ceramics containing micro surface defects introduced by FIB. Full article

(This article belongs to the Section Advanced Materials Characterization)

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Review

Jump to: Research, Other

21 pages, 1180 KiB

Open AccessReview

Fabrication Approaches to Interconnect Based Devices for Stretchable Electronics: A Review

by Steven Nagels^1,2 and Wim Deferme^1,2,*

¹ Institute for Materials Research, Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek, Belgium

² IMEC VZW—Division IMOMEC, Wetenschapspark 1, B-3590 Diepenbeek, Belgium

Materials 2018, 11(3), 375; https://doi.org/10.3390/ma11030375 - 3 Mar 2018

Cited by 32 | Viewed by 10899

Abstract

Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. [...] Read more.

Stretchable electronics promise to naturalize the way that we are surrounded by and interact with our devices. Sensors that can stretch and bend furthermore have become increasingly relevant as the technology behind them matures rapidly from lab-based workflows to industrially applicable production principles. Regardless of the specific materials used, creating stretchable conductors involves either the implementation of strain reliefs through insightful geometric patterning, the dispersion of stiff conductive filler in an elastomeric matrix, or the employment of intrinsically stretchable conductive materials. These basic principles however have spawned a myriad of materials systems wherein future application engineers need to find their way. This paper reports a literature study on the spectrum of different approaches towards stretchable electronics, discusses standardization of characteristic tests together with their reports and estimates matureness for industry. Patterned copper foils that are embedded in elastomeric sheets, which are closest to conventional electronic circuits processing, make up one end of the spectrum. Furthest from industry are the more recent circuits based on intrinsically stretchable liquid metals. These show extremely promising results, however, as a technology, liquid metal is not mature enough to be adapted. Printing makes up the transition between both ends, and is also well established on an industrial level, but traditionally not linked to creating electronics. Even though a certain level of maturity was found amongst the approaches that are reviewed herein, industrial adaptation for consumer electronics remains unpredictable without a designated break-through commercial application. Full article

(This article belongs to the Special Issue Stretchable and Flexible Electronic Materials & Devices)

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21 pages, 2849 KiB

Open AccessFeature PaperReview

Liquid Crystal Elastomers—A Path to Biocompatible and Biodegradable 3D-LCE Scaffolds for Tissue Regeneration

by Marianne E. Prévôt¹

, Senay Ustunel^1,2

and Elda Hegmann^1,2,3,*

¹ Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA

² Chemical Physics Interdisciplinary Program (CPIP), Kent State University, Kent, OH 44242, USA

³ Department of Biological Sciences, Kent State University, Kent, OH 44242, USA

Materials 2018, 11(3), 377; https://doi.org/10.3390/ma11030377 - 3 Mar 2018

Cited by 64 | Viewed by 11968

Abstract

The development of appropriate materials that can make breakthroughs in tissue engineering has long been pursued by the scientific community. Several types of material have been long tested and re-designed for this purpose. At the same time, liquid crystals (LCs) have captivated the [...] Read more.

The development of appropriate materials that can make breakthroughs in tissue engineering has long been pursued by the scientific community. Several types of material have been long tested and re-designed for this purpose. At the same time, liquid crystals (LCs) have captivated the scientific community since their discovery in 1888 and soon after were thought to be, in combination with polymers, artificial muscles. Within the past decade liquid crystal elastomers (LCE) have been attracting increasing interest for their use as smart advanced materials for biological applications. Here, we examine how LCEs can potentially be used as dynamic substrates for culturing cells, moving away from the classical two-dimensional cell-culture nature. We also briefly discuss the integration of a few technologies for the preparation of more sophisticated LCE-composite scaffolds for more dynamic biomaterials. The anisotropic properties of LCEs can be used not only to promote cell attachment and the proliferation of cells, but also to promote cell alignment under LCE-stimulated deformation. 3D LCEs are ideal materials for new insights to simulate and study the development of tissues and the complex interplay between cells. Full article

(This article belongs to the Special Issue Liquid Crystal-Assisted Advanced Functional Materials)

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18 pages, 3675 KiB

Open AccessFeature PaperReview

Recent Advances in Discotic Liquid Crystal-Assisted Nanoparticles

by Ashwathanarayana Gowda and Sandeep Kumar^*

Soft Condensed Matter Group, Raman Research Institute, C.V. Raman Avenue, Sadashivnagar, Bangalore 560 080, India

Materials 2018, 11(3), 382; https://doi.org/10.3390/ma11030382 - 5 Mar 2018

Cited by 39 | Viewed by 8253

Abstract

This article primarily summarizes recent advancement in the field of discotic liquid crystal (DLC) nanocomposites. Discotic liquid crystals are nanostructured materials, usually 2 to 6 nm size and have been recognized as organic semiconducting materials. Recently, it has been observed that the dispersion [...] Read more.

This article primarily summarizes recent advancement in the field of discotic liquid crystal (DLC) nanocomposites. Discotic liquid crystals are nanostructured materials, usually 2 to 6 nm size and have been recognized as organic semiconducting materials. Recently, it has been observed that the dispersion of small concentration of various functionalized zero-, one- and two-dimensional nanomaterials in the supramolecular order of mesophases of DLCs imparts negligible impact on liquid crystalline properties but enhances their thermal, supramolecular and electronic properties. Synthesis, characterization and dispersion of various nanoparticles in different discotics are presented. Full article

(This article belongs to the Special Issue Liquid Crystal-Assisted Advanced Functional Materials)

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8 pages, 8071 KiB

Open AccessFeature PaperReview

Advancements, Challenges and Prospects of Chemical Vapour Pressure at Atmospheric Pressure on Vanadium Dioxide Structures

by Charalampos Drosos¹

and Dimitra Vernardou^2,3,*

¹ Delta Nano-Engineering Solutions Ltd., Paddock Wood, Kent TN12 6EL, UK

² Center of Materials Technology and Photonics, School of Applied Technology, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece

³ Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete, Greece

Materials 2018, 11(3), 384; https://doi.org/10.3390/ma11030384 - 5 Mar 2018

Cited by 21 | Viewed by 5899

Abstract

Vanadium (IV) oxide (VO₂) layers have received extensive interest for applications in smart windows to batteries and gas sensors due to the multi-phases of the oxide. Among the methods utilized for their growth, chemical vapour deposition is a technology that is [...] Read more.

Vanadium (IV) oxide (VO₂) layers have received extensive interest for applications in smart windows to batteries and gas sensors due to the multi-phases of the oxide. Among the methods utilized for their growth, chemical vapour deposition is a technology that is proven to be industrially competitive because of its simplicity when performed at atmospheric pressure (APCVD). APCVD’s success has shown that it is possible to create tough and stable materials in which their stoichiometry may be precisely controlled. Initially, we give a brief overview of the basic processes taking place during this procedure. Then, we present recent progress on experimental procedures for isolating different polymorphs of VO₂. We outline emerging techniques and processes that yield in optimum characteristics for potentially useful layers. Finally, we discuss the possibility to grow 2D VO₂ by APCVD. Full article

(This article belongs to the Special Issue Advances in Chemical Vapor Deposition)

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27 pages, 7728 KiB

Open AccessFeature PaperReview

All-in-One Gel-Based Electrochromic Devices: Strengths and Recent Developments

by Yolanda Alesanco

, Ana Viñuales^*, Javier Rodriguez and Ramón Tena-Zaera

CIDETEC, Paseo Miramón, 196, 20014 Donostia-San Sebastian, Spain

Materials 2018, 11(3), 414; https://doi.org/10.3390/ma11030414 - 10 Mar 2018

Cited by 103 | Viewed by 14993

Abstract

Electrochromic devices (ECDs) have aroused great interest because of their potential applicability in displays and smart systems, including windows, rearview mirrors, and helmet visors. In the last decades, different device structures and materials have been proposed to meet the requirements of commercial applications [...] Read more.

Electrochromic devices (ECDs) have aroused great interest because of their potential applicability in displays and smart systems, including windows, rearview mirrors, and helmet visors. In the last decades, different device structures and materials have been proposed to meet the requirements of commercial applications to boost market entry. To this end, employing simple device architectures and achieving a competitive electrolyte are crucial to accomplish easily implementable, high-performance ECDs. The present review outlines devices comprising gel electrolytes as a single electroactive layer (“all-in-one”) ECD architecture, highlighting some advantages and opportunities they offer over other electrochromic systems. In this context, gel electrolytes not only overcome the drawbacks of liquid and solid electrolytes, such as liquid’s low chemical stability and risk of leaking and soil’s slow switching and lack of transparency, but also exhibit further strengths. These include easier processability, suitability for flexible substrates, and improved stabilization of the chemical species involved in redox processes, leading to better cyclability and opening wide possibilities to extend the electrochromic color palette, as discussed herein. Finally, conclusions and outlook are provided. Full article

(This article belongs to the Special Issue Organic Electrochromic Materials)

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11 pages, 3082 KiB

Open AccessReview

Role of the Short Distance Order in Glass Reactivity

by María Vallet-Regi^1,*

and Antonio J. Salinas^2,*

¹ Departamento de Química en Ciencias Farmacéuticas, Universidad Complutense de Madrid, Instituto de Investigación Sanitaria Hospital, 12 de Octubre imas12, 28040 Madrid, Spain

² Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), 28040 Madrid, Spain

Materials 2018, 11(3), 415; https://doi.org/10.3390/ma11030415 - 11 Mar 2018

Cited by 13 | Viewed by 4303

Abstract

In 2005, our group described for the first time the structural characterization at the atomic scale of bioactive glasses and the influence of the glasses’ nanostructure in their reactivity in simulated body fluids. In that study, two bioactive sol-gel glasses with composition 80%SiO [...] Read more.

In 2005, our group described for the first time the structural characterization at the atomic scale of bioactive glasses and the influence of the glasses’ nanostructure in their reactivity in simulated body fluids. In that study, two bioactive sol-gel glasses with composition 80%SiO₂–20%CaO and 80%SiO₂–17%CaO–3%P₂O₅ (in mol-%) were characterized by High-Resolution Transmission Electron Microscopy (HRTEM). Such characterization revealed unknown features of the glasses’ structure at the local scale that allowed the understanding of their different in vitro behaviors as a consequence of the presence or absence of P₂O₅. Since then, the nanostructure of numerous bioactive glasses, including melt-prepared, sol-gel derived, and mesoporous glasses, was investigated by HRTEM, Nuclear Magnetic Resonance (NMR) spectroscopy, Molecular Dynamics (MD) simulations, and other experimental techniques. These studies have shown that although glasses are amorphous solids, a certain type of short distance order, which greatly influences the in vitro and in vivo reactivity, is always present. This paper reviews the most significant advances in the understanding of bioactive glasses that took place in the last years as a result of the growing knowledge of the glasses’ nanostructure. Full article

(This article belongs to the Special Issue Selected papers from EUROMAT 2017 Conference—Biomaterials)

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Graphical abstract

20 pages, 1265 KiB

Open AccessReview

Machining of Fibre Reinforced Plastic Composite Materials

by Alessandra Caggiano^1,2

¹ Fraunhofer Joint Laboratory of Excellence on Advanced Production Technology (Fh-J_LEAPT UniNaples), 80125 Naples, Italy

² Department of Industrial Engineering, University of Naples Federico II, 80125 Naples, Italy

Materials 2018, 11(3), 442; https://doi.org/10.3390/ma11030442 - 18 Mar 2018

Cited by 99 | Viewed by 9907

Abstract

Fibre reinforced plastic composite materials are difficult to machine because of the anisotropy and inhomogeneity characterizing their microstructure and the abrasiveness of their reinforcement components. During machining, very rapid cutting tool wear development is experienced, and surface integrity damage is often produced in [...] Read more.

Fibre reinforced plastic composite materials are difficult to machine because of the anisotropy and inhomogeneity characterizing their microstructure and the abrasiveness of their reinforcement components. During machining, very rapid cutting tool wear development is experienced, and surface integrity damage is often produced in the machined parts. An accurate selection of the proper tool and machining conditions is therefore required, taking into account that the phenomena responsible for material removal in cutting of fibre reinforced plastic composite materials are fundamentally different from those of conventional metals and their alloys. To date, composite materials are increasingly used in several manufacturing sectors, such as the aerospace and automotive industry, and several research efforts have been spent to improve their machining processes. In the present review, the key issues that are concerning the machining of fibre reinforced plastic composite materials are discussed with reference to the main recent research works in the field, while considering both conventional and unconventional machining processes and reporting the more recent research achievements. For the different machining processes, the main results characterizing the recent research works and the trends for process developments are presented. Full article

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13 pages, 1989 KiB

Open AccessReview

Overview of Piezoelectric Biosensors, Immunosensors and DNA Sensors and Their Applications

by Miroslav Pohanka

Faculty of Military Health Sciences, University of Defense, Trebesska 1575, Hradec Kralove CZ-50001, Czech Republic

Materials 2018, 11(3), 448; https://doi.org/10.3390/ma11030448 - 19 Mar 2018

Cited by 307 | Viewed by 19228

Abstract

Piezoelectric biosensors are a group of analytical devices working on a principle of affinity interaction recording. A piezoelectric platform or piezoelectric crystal is a sensor part working on the principle of oscillations change due to a mass bound on the piezoelectric crystal surface. [...] Read more.

Piezoelectric biosensors are a group of analytical devices working on a principle of affinity interaction recording. A piezoelectric platform or piezoelectric crystal is a sensor part working on the principle of oscillations change due to a mass bound on the piezoelectric crystal surface. In this review, biosensors having their surface modified with an antibody or antigen, with a molecularly imprinted polymer, with genetic information like single stranded DNA, and biosensors with bound receptors of organic of biochemical origin, are presented and discussed. The mentioned recognition parts are frequently combined with use of nanoparticles and applications in this way are also introduced. An overview of the current literature is given and the methods presented are commented upon. Full article

(This article belongs to the Special Issue Piezoelectric Materials and Devices)

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18 pages, 7036 KiB

Open AccessFeature PaperReview

Metal-Insulator-Metal-Based Plasmonic Metamaterial Absorbers at Visible and Infrared Wavelengths: A Review

by Shinpei Ogawa^1,*

and Masafumi Kimata²

¹ Advanced Technology R&D Center, Mitsubishi Electric Corporation, 8-1-1 Tsukaguchi-Honmachi, Amagasaki, Hyogo 661-8661, Japan

² College of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan

Materials 2018, 11(3), 458; https://doi.org/10.3390/ma11030458 - 20 Mar 2018

Cited by 180 | Viewed by 19387

Abstract

Electromagnetic wave absorbers have been investigated for many years with the aim of achieving high absorbance and tunability of both the absorption wavelength and the operation mode by geometrical control, small and thin absorber volume, and simple fabrication. There is particular interest in [...] Read more.

Electromagnetic wave absorbers have been investigated for many years with the aim of achieving high absorbance and tunability of both the absorption wavelength and the operation mode by geometrical control, small and thin absorber volume, and simple fabrication. There is particular interest in metal-insulator-metal-based plasmonic metamaterial absorbers (MIM-PMAs) due to their complete fulfillment of these demands. MIM-PMAs consist of top periodic micropatches, a middle dielectric layer, and a bottom reflector layer to generate strong localized surface plasmon resonance at absorption wavelengths. In particular, in the visible and infrared (IR) wavelength regions, a wide range of applications is expected, such as solar cells, refractive index sensors, optical camouflage, cloaking, optical switches, color pixels, thermal IR sensors, IR microscopy and gas sensing. The promising properties of MIM-PMAs are attributed to the simple plasmonic resonance localized at the top micropatch resonators formed by the MIMs. Here, various types of MIM-PMAs are reviewed in terms of their historical background, basic physics, operation mode design, and future challenges to clarify their underlying basic design principles and introduce various applications. The principles presented in this review paper can be applied to other wavelength regions such as the ultraviolet, terahertz, and microwave regions. Full article

(This article belongs to the Special Issue New Horizon of Plasmonics and Metamaterials)

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Other

Jump to: Research, Review

1 pages, 142 KiB

Open AccessErratum

Erratum: Andreotti, S.; Franzoni, E.; Fabbri, P. Poly(hydroxyalkanoate)s-Based Hydrophobic Coatings for the Protection of Stone in Cultural Heritage. Materials 2018, 11, 165

by Serena Andreotti^1,2, Elisa Franzoni^1,2,*

, Micaela Degli Esposti^1,2

and Paola Fabbri^1,2

¹ Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, 40131 Bologna, Italy

² Consorzio Interuniversitario di Scienza e Tecnologia dei Materiali (INSTM), 50121 Firenze, Italy

Materials 2018, 11(3), 389; https://doi.org/10.3390/ma11030389 - 7 Mar 2018

Cited by 5 | Viewed by 2781

Abstract

The authors wish to add a new author, Micaela Degli Esposti, who also contributed to performing the experiments and analyzing the data of this published paper [1]. [...] Full article

(This article belongs to the Special Issue Recent Advances in Smart Materials for the Built Environment)

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