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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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15 pages, 5714 KiB  
Article
Guard Ring Design to Prevent Edge Breakdown in Double-Diffused Planar InGaAs/InP Avalanche Photodiodes
by Yu-Chun Chen, Ruei-Hong Yan, Hsu-Chia Huang, Liang-Hsuan Nieh and Hao-Hsiung Lin
Materials 2023, 16(4), 1667; https://doi.org/10.3390/ma16041667 - 16 Feb 2023
Cited by 1 | Viewed by 3461
Abstract
We report on the design of an attached guard ring (AGR) and a floating guard ring (FGR) in a planar separate absorption, grading, charge, and multiplication In0.53Ga0.47As/InP avalanche photodiode to prevent premature edge breakdowns. The depths of the two [...] Read more.
We report on the design of an attached guard ring (AGR) and a floating guard ring (FGR) in a planar separate absorption, grading, charge, and multiplication In0.53Ga0.47As/InP avalanche photodiode to prevent premature edge breakdowns. The depths of the two Zn diffusions were utilized to manipulate the guard ring structures. Results from TCAD simulation indicate that the optimal AGR diffusion depth is right at the turning point where the breakdown current shifts from the edge of active region to the AGR region. The devices with optimal AGR depth contain significantly higher breakdown voltages than those of devices either with shallower—or without any— AGR. For the FGR design, a series of devices with different spacings between AGR and FGR and different FGR opening widths for diffusion were fabricated and characterized. We show that when the spacing is longer than the critical value, the breakdown voltage can increase ~1.5 V higher than those of the APD devices without FGR. In addition, the wider the FGR opening width, the higher the breakdown voltage. TCAD simulations were also performed to study the effect of FGR, but showed less pronounced improvements, which could be due the discrepancy between the calculated and experimental diffusion profile. Full article
(This article belongs to the Special Issue Opto/Electronics Materials and Devices Applied for Telecommunications)
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12 pages, 3917 KiB  
Article
An Ultra-Broadband and Highly-Efficient Metamaterial Absorber with Stand-Up Gradient Impedance Graphene Films
by Bian Wu, Biao Chen, Shuai Ma, Ding Zhang and Hao-Ran Zu
Materials 2023, 16(4), 1617; https://doi.org/10.3390/ma16041617 - 15 Feb 2023
Cited by 6 | Viewed by 2131
Abstract
Metamaterial absorbers (MMAs) that absorb electromagnetic waves among an ultra-broad frequency band have attracted great attention in military and civilian applications. In this paper, an ultra-broadband and highly-efficient MMA is presented. The unit cell of the proposed MMA was constructed with two cross-placed [...] Read more.
Metamaterial absorbers (MMAs) that absorb electromagnetic waves among an ultra-broad frequency band have attracted great attention in military and civilian applications. In this paper, an ultra-broadband and highly-efficient MMA is presented. The unit cell of the proposed MMA was constructed with two cross-placed stand-up gradient impedance graphene films, which play a key role in improving impedance matching. Considering the trade-off between absorbing performance and processing complexity, in our design, we adopted the stand-up graphene films that have a gradient with three orders of magnitude in total. The simulated results of the proposed absorber show an ultra-broadband absorption (absorptivity > 90%) from 1.8 GHz to 66.7 GHz and a highly-efficient absorption (absorptivity > 97%) in the range of 2–21.7 GHz and 39.6–57 GHz. The field analysis was adopted to explain the mechanism of the proposed absorber. To validate this design, a prototype of 20 × 20 units was processed and assembled. The graphene films were processed with graphene conductive ink using screen print technology. The measured results are in good agreement with the simulated ones. The proposed absorber may find potential applications in the field of stealth technologies and electromagnetic interference. Full article
(This article belongs to the Special Issue Application of Graphene-Based Materials in Sensors and RF Electronics)
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10 pages, 2714 KiB  
Article
Graphene/PVDF Nanocomposite-Based Accelerometer for Detection of Low Vibrations
by Surendra Maharjan, Victor K. Samoei and Ahalapitiya H. Jayatissa
Materials 2023, 16(4), 1586; https://doi.org/10.3390/ma16041586 - 14 Feb 2023
Cited by 6 | Viewed by 2766
Abstract
A flexible piezoresistive sensor was developed as an accelerometer based on Graphene/PVDF nanocomposite to detect low-frequency and low amplitude vibration of industrial machines, which may be caused due to misalignment, looseness of fasteners, or eccentric rotation. The sensor was structured as a cantilever [...] Read more.
A flexible piezoresistive sensor was developed as an accelerometer based on Graphene/PVDF nanocomposite to detect low-frequency and low amplitude vibration of industrial machines, which may be caused due to misalignment, looseness of fasteners, or eccentric rotation. The sensor was structured as a cantilever beam with the proof mass at the free end. The vibration caused the proof mass to accelerate up and down, which was converted into an electrical signal. The output was recorded as the change in resistance (response percentage) with respect to the acceleration. It was found that this accelerometer has a capability of detecting acceleration up to 8 gpk-pk in the frequency range of 20 Hz to 80 Hz. The developed accelerometer has the potential to represent an alternative to the existing accelerometers due to its compactness, simplicity, and higher sensitivity for low frequency and low amplitude applications. Full article
(This article belongs to the Special Issue Low-Dimensional Structures for Smart Materials and Composites: Preparation, Properties and Applications)
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19 pages, 9066 KiB  
Article
Epoxy and Bio-Based Epoxy Carbon Fiber Twill Composites: Comparison of the Quasi-Static Properties
by Carlo Boursier Niutta, Raffaele Ciardiello, Andrea Tridello and Davide S. Paolino
Materials 2023, 16(4), 1601; https://doi.org/10.3390/ma16041601 - 14 Feb 2023
Cited by 15 | Viewed by 2520
Abstract
In recent years, interest in sustainability has significantly increased in many industrial sectors. Sustainability can be achieved with both lightweight design and eco-friendly manufacturing processes. For example, concerns on the use of thermoset composite materials, with a lightweight design and a high specific [...] Read more.
In recent years, interest in sustainability has significantly increased in many industrial sectors. Sustainability can be achieved with both lightweight design and eco-friendly manufacturing processes. For example, concerns on the use of thermoset composite materials, with a lightweight design and a high specific strength, have arisen, since thermoset resins are not fully recyclable and are mainly petrol based. A possible solution to this issue is the replacement of the thermoset matrix with a recyclable or renewable matrix, such as bio-based resin. However, the mechanical properties of composites made with bio-based resin should be carefully experimentally assessed to guarantee a safe design and the structural integrity of the components. In this work, the quasi-static mechanical properties of composite specimens (eight layers of carbon fiber fabric) made with commercially available epoxy and a bio-based epoxy resins (31% bio content) are compared. Tensile tests on the investigated resins and tensile, compression, shear and flexural tests have been carried out on composite laminates manufactured with the two investigated resins. A finite element model has been calibrated in the LS-Dyna environment using the experimentally assessed mechanical properties. The experimental results have proven that the two composites showed similar quasi-static properties, proving that bio-based composite materials can be reliably employed as a substitute for epoxy resins without affecting the structural integrity of the component but lowering their carbon footprint. Full article
(This article belongs to the Special Issue Recent Advances in Biobased and Biodegradable Polymers)
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14 pages, 7008 KiB  
Article
Silver Nanoparticles for Fluorescent Nanocomposites by High-Pressure Magnetron Sputtering
by Tomáš Zikmund, Jiří Bulíř, Michal Novotný, Ladislav Fekete, Sergii Chertopalov, Stefan Andrei Irimiciuc, Mariana Klementová, Jarmila Balogová and Jan Lančok
Materials 2023, 16(4), 1591; https://doi.org/10.3390/ma16041591 - 14 Feb 2023
Cited by 5 | Viewed by 2182
Abstract
We report on the formation of silver nanoparticles by gas aggregation in a reaction chamber at room temperature. The size distribution of nanoparticles deposited on a silicon substrate for various lengths of an aggregation (high-pressure) chamber was investigated by atomic force microscopy. Nanoparticles [...] Read more.
We report on the formation of silver nanoparticles by gas aggregation in a reaction chamber at room temperature. The size distribution of nanoparticles deposited on a silicon substrate for various lengths of an aggregation (high-pressure) chamber was investigated by atomic force microscopy. Nanoparticles were characterized by scanning and transmission electron microscopy and spectral ellipsometry. The physical shape of the nanoparticles and its distribution was correlated with their optical properties. Metal–dielectric nanocomposites were deposited employing simultaneous deposition of Ag NPs via high-pressure magnetron sputtering and the dielectric matrix was deposited via thermal evaporation. Pure and Eu-, Er-, and Yb-doped lithium fluoride was used as the dielectric host matrix. Optical transmittance of lithium fluoride containing silver nanoparticles was measured and their theoretical absorption cross-section calculated. The nanoparticles were also embedded in Eu3+-doped downshifting and Er3+- and Yb3+-doped up-conversion materials to study their influence on emission spectra. Spectra of identical layers with and without nanoparticles were compared. Their transmittance at various annealing temperatures is also presented. Full article
(This article belongs to the Special Issue Structural, Morphological, and Optical Properties of Functional Thin Films)
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18 pages, 9058 KiB  
Review
The Historical Development of Infrared Photodetection Based on Intraband Transitions
by Qun Hao, Xue Zhao, Xin Tang and Menglu Chen
Materials 2023, 16(4), 1562; https://doi.org/10.3390/ma16041562 - 13 Feb 2023
Cited by 7 | Viewed by 3389
Abstract
The infrared technology is entering widespread use as it starts fulfilling a growing number of emerging applications, such as smart buildings and automotive sectors. Majority of infrared photodetectors are based on interband transition, which is the energy gap between the valence band and [...] Read more.
The infrared technology is entering widespread use as it starts fulfilling a growing number of emerging applications, such as smart buildings and automotive sectors. Majority of infrared photodetectors are based on interband transition, which is the energy gap between the valence band and the conduction band. As a result, infrared materials are mainly limited to semi-metal or ternary alloys with narrow-bandgap bulk semiconductors, whose fabrication is complex and expensive. Different from interband transition, intraband transition utilizing the energy gap inside the band allows for a wider choice of materials. In this paper, we mainly discuss the recent developments on intraband infrared photodetectors, including ‘bottom to up’ devices such as quantum well devices based on the molecular beam epitaxial approach, as well as ‘up to bottom’ devices such as colloidal quantum dot devices based on the chemical synthesis. Full article
(This article belongs to the Section Quantum Materials)
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12 pages, 4312 KiB  
Article
Single Crystals of EuScCuSe3: Synthesis, Experimental and DFT Investigations
by Maxim V. Grigoriev, Anna V. Ruseikina, Vladimir A. Chernyshev, Aleksandr S. Oreshonkov, Alexander A. Garmonov, Maxim S. Molokeev, Ralf J. C. Locke, Andrey V. Elyshev and Thomas Schleid
Materials 2023, 16(4), 1555; https://doi.org/10.3390/ma16041555 - 13 Feb 2023
Cited by 4 | Viewed by 2063
Abstract
EuScCuSe3 was synthesized from the elements for the first time by the method of cesium-iodide flux. The crystal belongs to the orthorhombic system (Cmcm) with the unit cell parameters a = 3.9883(3) Å, b = 13.2776(9) Å, c = 10.1728(7) [...] Read more.
EuScCuSe3 was synthesized from the elements for the first time by the method of cesium-iodide flux. The crystal belongs to the orthorhombic system (Cmcm) with the unit cell parameters a = 3.9883(3) Å, b = 13.2776(9) Å, c = 10.1728(7) Å, V = 538.70(7) Å3. Density functional (DFT) methods were used to study the crystal structure stability of EuScCuSe3 in the experimentally obtained Cmcm and the previously proposed Pnma space groups. It was shown that analysis of elastic properties as Raman and infrared spectroscopy are powerless for this particular task. The instability of EuScCuSe3 in space group Pnma space group is shown on the basis of phonon dispersion curve simulation. The EuScCuSe3 can be assigned to indirect wide-band gap semiconductors. It exhibits the properties of a soft ferromagnet at temperatures below 2 K. Full article
(This article belongs to the Special Issue Advances in Density Functional Theory (DFT) Studies of Solids (Second Volume))
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8 pages, 3445 KiB  
Article
Effect of Surface Dispersion of Fe Nanoparticles on the Room-Temperature Flash Sintering Behavior of 3YSZ
by Angxuan Wu, Yuchen Zhu, Chen Xu, Nianping Yan, Xuetong Zhao, Xilin Wang and Zhidong Jia
Materials 2023, 16(4), 1544; https://doi.org/10.3390/ma16041544 - 13 Feb 2023
Cited by 2 | Viewed by 1920
Abstract
Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the [...] Read more.
Arc floating in surface flashover can be controlled by reducing the interfacial charge-transfer resistance of ceramics. However, thus far, only a few studies have been conducted on methods of treating ceramic surfaces directly to reduce the interfacial charge-transfer resistance. Herein, we explore the flash sintering behavior of a ceramic surface (3 mol% yttria-stabilized zirconia (3YSZ)) onto which loose metal (iron) powder was spread prior to flash sintering at room temperature (25 °C). The iron powder acts as a conductive phase that accelerates the start of flash sintering while also doping the ceramic phase during the sintering process. Notably, the iron powder substantially reduces the transition time from the arc stage to the flash stage from 13.50 to 8.22 s. The surface temperature (~1600 °C) of the ceramic substrate is sufficiently high to melt the iron powder. The molten metal then reacts with the ceramic surface, causing iron ions to substitute Zr4+ ions and promoting rapid densification. The YSZ grains in the metal-infiltrated area grow exceptionally fast. The results demonstrate that spreading metal powder onto a ceramic surface prior to flash sintering can enable the metal to enter the ceramic pores, which will be of significance in developing and enhancing ceramic–metal powder processing techniques. Full article
(This article belongs to the Special Issue Advanced Ceramics and Composites: Design, Structure, Processing, Properties, and Applications)
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17 pages, 12522 KiB  
Article
Porous Thermoplastic Molded Regenerated Silk Crosslinked by the Addition of Citric Acid
by Alessio Bucciarelli, Nicola Vighi, Alessandra Maria Bossi, Brunella Grigolo and Devid Maniglio
Materials 2023, 16(4), 1535; https://doi.org/10.3390/ma16041535 - 12 Feb 2023
Cited by 1 | Viewed by 2469
Abstract
Thermoplastic molded regenerated silk fibroin was proposed as a structural material in tissue engineering applications, mainly for application in bone. The protocol allows us to obtain a compact non-porous material with a compression modulus in the order of a Giga Pascal in dry [...] Read more.
Thermoplastic molded regenerated silk fibroin was proposed as a structural material in tissue engineering applications, mainly for application in bone. The protocol allows us to obtain a compact non-porous material with a compression modulus in the order of a Giga Pascal in dry conditions (and in the order of tens of MPa in wet conditions). This material is produced by compressing a lyophilized silk fibroin powder or sponge into a mold temperature higher than the glass transition temperature. The main purpose of the produced resin was the osteofixation and other structural applications in which the lack of porosity was not an issue. In this work, we introduced the use of citric acid in the thermoplastic molding protocol of silk fibroin to obtain porosity inside the structural material. The citric acid powder during the compression acted as a template for the pore formation. The mean pore diameter achieved by the addition of the higher amount of citric acid was around 5 μm. In addition, citric acid could effectively crosslink the silk fibroin chain, improving its mechanical strength. This effect was proved both by evaluating the compression modulus (the highest value recorded was 77 MPa in wet conditions) and by studying the spectra obtained by Fourier transform infrared spectroscopy. This protocol may be applied in the near future to the production of structural bone scaffolds. Full article
(This article belongs to the Special Issue Synthesis, Optimization, and Reuse of Sustainable Bio-Based Materials)
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21 pages, 3534 KiB  
Article
Parametric Study of the Influence of Nonlinear Elastic Characteristics of Rail Pads on Wheel–Rail Vibrations
by Traian Mazilu, Mădălina Dumitriu and Ionuț-Radu Răcănel
Materials 2023, 16(4), 1531; https://doi.org/10.3390/ma16041531 - 12 Feb 2023
Cited by 7 | Viewed by 2195
Abstract
The rail pad is the elastic element between the rail and the sleeper that has the role of absorbing the mechanical stresses from the rail and reducing the vibrations and shocks generated by wheel–rail interactions. In this paper, the problem of the influence [...] Read more.
The rail pad is the elastic element between the rail and the sleeper that has the role of absorbing the mechanical stresses from the rail and reducing the vibrations and shocks generated by wheel–rail interactions. In this paper, the problem of the influence of the variability of the nonlinear load-deformation characteristic of rail pads (resulting from the manufacturing process) on wheel–rail vibrations is investigated. The limit load-deformation characteristics of a manufactured rail pad and the medium load-deformation characteristic resulting as the arithmetic mean of the two are considered. The nonlinear load-deformation characteristic of the ballast is also considered. All these characteristics are approximated with the help of the bilinear function and are implemented in a track model consisting of an infinite Euler-Bernoulli beam placed on a two-elastic layer continuous foundation with inertial insertion, resulting in a model with an inhomogeneous foundation. The parameters of the inhomogeneous foundation are established from the equilibrium condition under a static load. Wheel–rail vibrations are studied in terms of the contact force and the acceleration of the rail and wheel. The influence of the variability of the elastic characteristics of the rail pad manifests itself in the field of medium frequencies, which amplify or attenuate the vibration levels in certain bands of one-third of an octave. Full article
(This article belongs to the Special Issue Research and Modeling of Materials Fatigue and Fracture)
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13 pages, 2105 KiB  
Article
Analyzing the Bolometric Performance of Vanadium Oxide Thin Films Modified by Carbon Nanotube Dispersions
by Usha Philipose, Chris Littler, Yan Jiang, Alia Naciri, Michael Harcrow and A. J. Syllaios
Materials 2023, 16(4), 1534; https://doi.org/10.3390/ma16041534 - 12 Feb 2023
Cited by 2 | Viewed by 2616
Abstract
The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of VOx films is investigated. For a critical range of the CNT dispersion density on VOx films, the intrinsic properties of the [...] Read more.
The influence of carbon nanotube (CNT) dispersions on the electrical properties and noise signal amplitude of VOx films is investigated. For a critical range of the CNT dispersion density on VOx films, the intrinsic properties of the VOx films are modified by the CNTs. The CNT concentrations reported in this work are about 0.3 μg/cm2 and 1.6 μg/cm2, allowing for low density and high density dispersions on the VOx film surface to be investigated. These values are higher than the percolation threshold of about 0.12 μg/cm2 for these films. The composite film exhibits a significant reduction in the temperature coefficient of resistance (TCR) (from ≈3.8% K−1 to ≈0.3% K−1) for high density dispersions. In contrast, while VOx–CNT composites with low density single wall CNT dispersions exhibit no significant change in TCR values, an approximate two orders of magnitude reduction in the low frequency 1/f noise is measured. The noise signal amplitude measured at 0.1 V and at 1.0 Hz reduces from 6 × 10−5V/(Hz) for VOx films to 5 × 10−7V/(Hz) for the low density SWCNT dispersion on VOx film and to 3 × 10−6V/(Hz) for the low density MWCNT dispersion on VOx film. The CNT concentration is the critical factor for yielding the observed changes in conductivity and low frequency noise. The results presented in this work provide a better understanding of VOx-based composites, thereby enabling the development of new, versatile and functional materials for device applications. Full article
(This article belongs to the Special Issue Feature Papers in Thin Films and Interfaces)
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17 pages, 5382 KiB  
Article
Green Synthesis, Characterization, and Empirical Thermal Conductivity Assessment of ZnO Nanofluids for High-Efficiency Heat-Transfer Applications
by Meriem Jebali, Gianpiero Colangelo and Ana Isabel Gómez-Merino
Materials 2023, 16(4), 1542; https://doi.org/10.3390/ma16041542 - 12 Feb 2023
Cited by 12 | Viewed by 2974
Abstract
ZnO nanoparticles were synthesized using lemon juice and zinc nitrate (1:1) through the green method. The structure of the biosynthesized ZnO nanoparticles was analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology and the size of [...] Read more.
ZnO nanoparticles were synthesized using lemon juice and zinc nitrate (1:1) through the green method. The structure of the biosynthesized ZnO nanoparticles was analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology and the size of ZnO nanoparticles were elucidated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The powder was highly dispersed and irregularly shaped and the size of the nanoparticles ranged from 28 to 270 nm, depending on the shape of the particles. Thermal conductivity of the biosynthesized ZnO PG/W mixture 40:60 (v/v) nanofluids was measured within the temperature range of 20–70 °C. Experimental results revealed a linear increase in thermal conductivity with the rise of temperature and volume fraction. The enhancement of this parameter with temperature was probably due to the different shapes of the former agglomerates. They were broken by the thermal energy in aggregates of different forms. A correlation of these structures with temperature was established. Finally, an empirical model was developed for predicting thermal conductivity with particle volume fraction and temperature. Full article
(This article belongs to the Special Issue Green Synthesis and Applications of Metallic Nanoparticles)
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15 pages, 8380 KiB  
Article
Antimicrobial Properties of TiNbSn Alloys Anodized in a Sulfuric Acid Electrolyte
by Yu Mori, Satoko Fujimori, Hiroaki Kurishima, Hiroyuki Inoue, Keiko Ishii, Maya Kubota, Kazuyoshi Kawakami, Naoko Mori, Toshimi Aizawa and Naoya Masahashi
Materials 2023, 16(4), 1487; https://doi.org/10.3390/ma16041487 - 10 Feb 2023
Cited by 4 | Viewed by 2202
Abstract
TiNbSn alloy is a high-performance titanium alloy which is biosafe, strong, and has a low Young’s modulus. TiNbSn alloy has been clinically applied as a material for orthopedic prosthesis. Anodized TiNbSn alloys with acetic and sulfuric acid electrolytes have excellent biocompatibility for osseointegration. [...] Read more.
TiNbSn alloy is a high-performance titanium alloy which is biosafe, strong, and has a low Young’s modulus. TiNbSn alloy has been clinically applied as a material for orthopedic prosthesis. Anodized TiNbSn alloys with acetic and sulfuric acid electrolytes have excellent biocompatibility for osseointegration. Herein, TiNbSn alloy was anodized in a sulfuric acid electrolyte to determine the antimicrobial activity. The photocatalytic activities of the anodic oxide alloys were investigated based on their electronic band structure and crystallinity. In addition, the cytotoxicity of the anodized TiNbSn alloy was evaluated using cell lines of the osteoblast and fibroblast lineages. The antimicrobial activity of the anodic oxide alloy was assessed according to the ISO 27447 using methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, and Escherichia coli. The anodic oxide comprised rutile and anatase titanium dioxide (TiO2) and exhibited a porous microstructure. A well-crystallized rutile TiO2 phase was observed in the anodized TiNbSn alloy. The methylene blue degradation tests under ultraviolet illumination exhibited photocatalytic activity. In antimicrobial tests, the anodized TiNbSn alloy exhibited robust antimicrobial activities under ultraviolet illumination for all bacterial species, regardless of drug resistance. Therefore, the anodized TiNbSn alloy can be used as a functional biomaterial with low Young’s modulus and excellent antimicrobial activity. Full article
(This article belongs to the Special Issue Mechanical Behavior of Biological and Bio-Inspired Materials)
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15 pages, 6239 KiB  
Article
Mammalian Oocyte Analysis by MALDI MSI with Wet-Interface Matrix Deposition Technique
by Anna Bodzon-Kulakowska, Wiesława Młodawska, Przemyslaw Mielczarek, Dorota Lachowicz, Piotr Suder and Marek Smoluch
Materials 2023, 16(4), 1479; https://doi.org/10.3390/ma16041479 - 9 Feb 2023
Cited by 3 | Viewed by 2219
Abstract
Oocytes are a special kind of biological material. Here, the individual variability of a single cell is important. It means that the opportunity to obtain information about the lipid content from the analysis of a single cell is significant. In our study, we [...] Read more.
Oocytes are a special kind of biological material. Here, the individual variability of a single cell is important. It means that the opportunity to obtain information about the lipid content from the analysis of a single cell is significant. In our study, we present a method for lipid analysis based on the MALDI-based mass spectrometry imaging (MSI) approach. Our attention was paid to the sample preparation optimization with the aid of a wet-interface matrix deposition system (matrix spraying). Technical considerations of the sample preparation process, such as the number of matrix layers and the position of the spraying nozzle during the matrix deposition, are presented in the article. Additionally, we checked if changing the 2,5-dihydroxybenzoic acid (DHB) and 9-Aminoacridine (9AA) matrix concentration and their solvent composition may improve the analysis. Moreover, the comparison of paraformaldehyde-fixed versus nonfixed cell analysis was performed. We hope that our approach will be helpful for those working on lipid analyses in extraordinary material such as a single oocyte. Our study may also offer clues for anybody interested in single-cell analysis with the aid of MALDI mass spectrometry imaging and the wet-interface matrix deposition method. Full article
(This article belongs to the Special Issue Mass Spectrometry in Materials Science)
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10 pages, 3179 KiB  
Article
Strong Plasmon-Mie Resonance in Si@Pd Core-Ω Shell Nanocavity
by Haomin Guo, Qi Hu, Chengyun Zhang, Haiwen Liu, Runmin Wu and Shusheng Pan
Materials 2023, 16(4), 1453; https://doi.org/10.3390/ma16041453 - 9 Feb 2023
Cited by 3 | Viewed by 2992
Abstract
The surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) can be used to enhance the generation of the hot electrons in plasmon metal nanocavity. In this paper, Pd nanomembrane (NMB) is sputtered on the surface of Si nanosphere (NS) on glass [...] Read more.
The surface plasmon resonance (SPR) and localized surface plasmon resonance (LSPR) can be used to enhance the generation of the hot electrons in plasmon metal nanocavity. In this paper, Pd nanomembrane (NMB) is sputtered on the surface of Si nanosphere (NS) on glass substrate to form the Si@Pd core-Ω shell nanocavity. A plasmon-Mie resonance is induced in the nanocavity by coupling the plasmon resonance with the Mie resonance to control the optical property of Si NS. When this nanocavity is excited by near-infrared-1 (NIR-1, 650 nm–900 nm) femtosecond (fs) laser, the luminescence intensity of Si NS is dramatically enhanced due to the synergistic interaction of plasmon and Mie resonance. The generation of resonance coupling regulates resonant mode of the nanocavity to realize multi-dimensional nonlinear optical response, which can be utilized in the fields of biological imaging and nanoscale light source. Full article
(This article belongs to the Special Issue Synthesis and Application of Advanced Optical and Optoelectronic Functional Materials)
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12 pages, 2084 KiB  
Article
Enhanced Thermoelectric Properties of Misfit Bi2Sr2-xCaxCo2Oy: Isovalent Substitutions and Selective Phonon Scattering
by Arindom Chatterjee, Ananya Banik, Alexandros El Sachat, José Manuel Caicedo Roque, Jessica Padilla-Pantoja, Clivia M. Sotomayor Torres, Kanishka Biswas, José Santiso and Emigdio Chavez-Angel
Materials 2023, 16(4), 1413; https://doi.org/10.3390/ma16041413 - 8 Feb 2023
Cited by 6 | Viewed by 2314
Abstract
Layered Bi-misfit cobaltates, such as Bi2Sr2Co2Oy, are the natural superlattice of an electrically insulating rocksalt (RS) type Bi2Sr2O4 layer and electrically conducting CoO2 layer, stacked along the crystallographic c-axis. [...] Read more.
Layered Bi-misfit cobaltates, such as Bi2Sr2Co2Oy, are the natural superlattice of an electrically insulating rocksalt (RS) type Bi2Sr2O4 layer and electrically conducting CoO2 layer, stacked along the crystallographic c-axis. RS and CoO2 layers are related through charge compensation reactions (or charge transfer). Therefore, thermoelectric transport properties are affected when doping or substitution is carried out in the RS layer. In this work, we have shown improved thermoelectric properties of spark plasma sintered Bi2Sr2-xCaxCo2Oy alloys (x = 0, 0.3 and 0.5). The substitution of Ca atoms affects the thermal properties by introducing point-defect phonon scattering, while the electronic conductivity and thermopower remain unaltered. Full article
(This article belongs to the Special Issue Thermoelectric Materials: Progress and Their Applications)
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22 pages, 8744 KiB  
Article
Abnormal Eu3+ → Eu2+ Reduction in Ca9−xMnxEu(PO4)7 Phosphors: Structure and Luminescent Properties
by Elena V. Sipina, Dmitry A. Spassky, Nataliya R. Krutyak, Vladimir A. Morozov, Evgenia S. Zhukovskaya, Alexei A. Belik, Mikhail S. Manylov, Bogdan I. Lazoryak and Dina V. Deyneko
Materials 2023, 16(4), 1383; https://doi.org/10.3390/ma16041383 - 7 Feb 2023
Cited by 7 | Viewed by 2674
Abstract
β-Ca3(PO4)2-type phosphors Ca9−xMnxEu(PO4)7 have been synthesized by high-temperature solid-phase reactions. The crystal structure of Ca8MnEu(PO4)7 was characterized by synchrotron X-ray diffraction. The phase transitions, [...] Read more.
β-Ca3(PO4)2-type phosphors Ca9−xMnxEu(PO4)7 have been synthesized by high-temperature solid-phase reactions. The crystal structure of Ca8MnEu(PO4)7 was characterized by synchrotron X-ray diffraction. The phase transitions, magnetic and photoluminescence (PL) properties were studied. The abnormal reduction Eu3+ → Eu2+ in air was observed in Ca9−xMnxEu(PO4)7 according to PL spectra study and confirmed by X-ray photoelectron spectroscopy (XPS). Eu3+ shows partial reduction and coexistence of Eu2+/3+ states. It reflects in combination of a broad band from the Eu2+ 4f65d1 → 4f7 transition and a series of sharp lines attributed to 5D0 → 7FJ transitions of Eu3+. Eu2+/Eu3+ ions are redistributed among two crystal sites, M1 and M3, while Mn2+ fully occupies octahedral site M5 in Ca8MnEu(PO4)7. The main emission band was attributed to the 5D0 → 7F2 electric dipole transition of Eu3+ at 395 nm excitation. The abnormal quenching of Eu3+ emission was observed in Ca9−xMnxEu(PO4)7 phosphors with doping of the host by Mn2+ ions. The phenomena of abnormal reduction and quenching were discussed in detail. Full article
(This article belongs to the Special Issue Advanced Materials for Optical and Luminescence Applications)
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33 pages, 12603 KiB  
Article
Application of the ps−Version of the Finite Element Method to the Analysis of Laminated Shells
by Cheng Angelo Yan and Riccardo Vescovini
Materials 2023, 16(4), 1395; https://doi.org/10.3390/ma16041395 - 7 Feb 2023
Cited by 2 | Viewed by 2064
Abstract
The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and [...] Read more.
The development of accurate and efficient numerical methods is of crucial importance for the analysis and design of composite structures. This is even more true in the presence of variable stiffness (VS) configurations, where intricate load paths can be responsible for complex and localized stress profiles. In this work, we present the ps−version of the finite elements method (ps−FEM), a novel FE approach which can perform global/local analysis through different refinement strategies efficiently and easily. Within this framework, the global behavior is captured through a p−refinement by increasing the polynomial order of the elements. For the local one, a mesh−superposition technique, called s−refinement, is used to improve locally the solution by defining a local/fine mesh overlaid to the global/coarse one. The combination of p− and s−refinements enables us to achieve excellent accuracy−to−cost ratios. This paper aims to present the numerical formulation and the implementation aspects of this novel approach to VS composite shell analysis. Numerical tests are reported to illustrate the potential of the method. The results provide a clear insight of its potential to guarantee fast convergence and easy mesh refinement where needed. Full article
(This article belongs to the Special Issue Feature Papers in Materials Simulation and Design)
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11 pages, 8368 KiB  
Article
Novel Artificial Scaffold for Bone Marrow Regeneration: Honeycomb Tricalcium Phosphate
by Yasunori Inada, Kiyofumi Takabatake, Hidetsugu Tsujigiwa, Keisuke Nakano, Qiusheng Shan, Tianyan Piao, Anqi Chang, Hotaka Kawai and Hitoshi Nagatsuka
Materials 2023, 16(4), 1393; https://doi.org/10.3390/ma16041393 - 7 Feb 2023
Cited by 3 | Viewed by 2062
Abstract
Bone marrow is complex structure containing heterogenetic cells, making it difficult to regenerate using artificial scaffolds. In a previous study, we succeeded in developing honeycomb tricalcium phosphate (TCP), which is a cylindrical scaffold with a honeycomb arrangement of straight pores, and we demonstrated [...] Read more.
Bone marrow is complex structure containing heterogenetic cells, making it difficult to regenerate using artificial scaffolds. In a previous study, we succeeded in developing honeycomb tricalcium phosphate (TCP), which is a cylindrical scaffold with a honeycomb arrangement of straight pores, and we demonstrated that TCP with 300 and 500 μm pore diameters (300TCP and 500TCP) induced bone marrow structure within the pores. In this study, we examined the optimal scaffold structure for bone marrow with homeostatic bone metabolism using honeycomb TCP. 300TCP and 500TCP were transplanted into rat muscle, and bone marrow formation was histologically assessed. Immunohistochemistry for CD45, CD34, Runt-related transcription factor 2 (Runx2), c-kit single staining, Runx2/N-cadherin, and c-kit/Tie-2 double staining was performed. The area of bone marrow structure, which includes CD45(+) round-shaped hematopoietic cells and CD34(+) sinusoidal vessels, was larger in 300TCP than in 500TCP. Additionally, Runx2(+) osteoblasts and c-kit(+) hematopoietic stem cells were observed on the surface of bone tissue formed within TCP. Among Runx2(+) osteoblasts, spindle-shaped N-cadherin(+) cells existed in association with c-kit(+)Tie-2(+) hematopoietic stem cells on the bone tissue formed within TCP, which formed a hematopoietic stem cell niche similar to as in vivo. Therefore, honeycomb TCP with 300 μm pore diameters may be an artificial scaffold with an optimal geometric structure as a scaffold for bone marrow formation. Full article
(This article belongs to the Special Issue Materials for Hard Tissue Repair and Regeneration (Second Volume))
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24 pages, 9738 KiB  
Article
Mechanical Behavior of Austenitic Steel under Multi-Axial Cyclic Loading
by Abhishek Biswas, Dzhem Kurtulan, Timothy Ngeru, Abril Azócar Guzmán, Stefanie Hanke and Alexander Hartmaier
Materials 2023, 16(4), 1367; https://doi.org/10.3390/ma16041367 - 6 Feb 2023
Cited by 2 | Viewed by 2220
Abstract
Low-nickel austenitic steel is subjected to high-pressure torsion fatigue (HPTF) loading, where a constant axial compression is overlaid with a cyclic torsion. The focus of this work lies on investigating whether isotropic J2 plasticity or crystal plasticity can describe the mechanical behavior during [...] Read more.
Low-nickel austenitic steel is subjected to high-pressure torsion fatigue (HPTF) loading, where a constant axial compression is overlaid with a cyclic torsion. The focus of this work lies on investigating whether isotropic J2 plasticity or crystal plasticity can describe the mechanical behavior during HPTF loading, particularly focusing on the axial creep deformation seen in the experiment. The results indicate that a J2 plasticity model with an associated flow rule fails to describe the axial creep behavior. In contrast, a micromechanical model based on an empirical crystal plasticity law with kinematic hardening described by the Ohno–Wang rule can match the HPTF experiments quite accurately. Hence, our results confirm the versatility of crystal plasticity in combination with microstructural models to describe the mechanical behavior of materials under reversing multiaxial loading situations. Full article
(This article belongs to the Special Issue Fatigue and Fracture of Metals and Alloys: Numerical and Experimental Study)
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13 pages, 1973 KiB  
Article
Ultrafiltration Membranes Modified with Reduced Graphene Oxide: Effect on Methyl Green Removal from Aqueous Solution
by María Dolores Murcia, Asunción M. Hidalgo, María Gómez, Gerardo León, Elisa Gómez and Marta Martínez
Materials 2023, 16(4), 1369; https://doi.org/10.3390/ma16041369 - 6 Feb 2023
Cited by 2 | Viewed by 2245
Abstract
In this work, three types of ultrafiltration membranes with different characteristics (GR60PP, RC70PP and GR80PP) have been tested for the removal of the dye methyl green. The tests were first carried out with the three membranes without any modification and then with the [...] Read more.
In this work, three types of ultrafiltration membranes with different characteristics (GR60PP, RC70PP and GR80PP) have been tested for the removal of the dye methyl green. The tests were first carried out with the three membranes without any modification and then with the membranes’ surfaces modified with reduced graphene oxide (rGO). The modification was achieved through physical treatment. The CR70PP membrane did not support the modification treatment and was discarded. The other membranes were initially characterized with distilled water tests to study the permeability to the solvent, and later, the permeate fluxes and the values of rejection coefficients were obtained at different working pressures with a fixed dye initial concentration. In addition, SEM images and SEM-EDX spectra of the native and modified membranes were obtained before and after the dye tests. The GR60PP membrane has shown the best results in relation to the modification because it has increased its rejection levels. On the opposite, the GR80PP membrane performs better without surface modification, achieving the highest rejection values and the highest permeate fluxes in its native form. Full article
(This article belongs to the Special Issue Development and Application of Novel Membranes)
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16 pages, 3980 KiB  
Article
A Numerical Model for Understanding the Development of Adhesion during Drying of Cellulose Model Surfaces
by Magdalena Kaplan and Sören Östlund
Materials 2023, 16(4), 1327; https://doi.org/10.3390/ma16041327 - 4 Feb 2023
Cited by 2 | Viewed by 1834
Abstract
Adhesion is crucial for the development of mechanical properties in fibre-network materials, such as paper or other cellulose fibre biocomposites. The stress transfer within the network is possible through the fibre–fibre joints, which develop their strength during drying. Model surfaces are useful for [...] Read more.
Adhesion is crucial for the development of mechanical properties in fibre-network materials, such as paper or other cellulose fibre biocomposites. The stress transfer within the network is possible through the fibre–fibre joints, which develop their strength during drying. Model surfaces are useful for studying the adhesive strength of joints by excluding other parameters influencing global performance, such as geometry, fibre fibrillation, or surface roughness. Here, a numerical model describes the development of adhesion between a cellulose bead and a rigid surface using an axisymmetric formulation, including moisture diffusion, hygroexpansion, and cohesive surfaces. It is useful for studying the development of stresses during drying. A calibration of model parameters against previously published contact and geometry measurements shows that the model can replicate the observed behaviour. A parameter study shows the influence of cohesive and material parameters on the contact area. The developed model opens possibilities for further studies on model surfaces, with quantification of the adhesion during pull-off measurements. Full article
(This article belongs to the Special Issue Mechanical Properties and Application of Adhesive Materials)
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11 pages, 5394 KiB  
Article
Optical Properties Investigation of Upconverting K2Gd(PO4)(WO4):20%Yb3+,Tm3+ Phosphors
by Julija Grigorjevaite and Arturas Katelnikovas
Materials 2023, 16(3), 1305; https://doi.org/10.3390/ma16031305 - 3 Feb 2023
Cited by 5 | Viewed by 2114
Abstract
Nowadays, scientists are interested in inorganic luminescence materials that can be excited with UV or NIR radiation and emit in the visible range. Such inorganic materials can be successfully used as luminescent or anti-counterfeiting pigments. In this work, we report the synthesis and [...] Read more.
Nowadays, scientists are interested in inorganic luminescence materials that can be excited with UV or NIR radiation and emit in the visible range. Such inorganic materials can be successfully used as luminescent or anti-counterfeiting pigments. In this work, we report the synthesis and optical properties investigation of solely Tm3+ doped and Yb3+/Tm3+ co-doped K2Gd(PO4)(WO4) phosphors. The single-phase samples were prepared using a solid-state reaction method. The Tm3+ concentration was changed from 0.5% to 5%. Downshifting and upconversion emission studies were performed under 360 nm and 980 nm excitation, respectively. Yb3+ ions were used as sensitizers in the K2Gd(PO4)(WO4) phosphors to transfer the captured energy to Tm3+ ions. It turned out that under UV excitation, phosphors emitted in the blue spectral area regardless of the presence or absence of Yb3+. However, a very strong deep-red (~800 nm) emission was observed when Yb3+ and Tm3+-containing samples were excited with a 980 nm wavelength laser. It is interesting that the highest upconversion emission in the UV/Visible range was achieved for 20% Yb3+, 0.5% Tm3+ doped sample, whereas the sample co-doped with 20% Yb3+, 2% Tm3+ showed the most intensive UC emission band in the NIR range. The materials were characterized using powder X-ray diffraction and scanning electron microscopy. Optical properties were studied using steady-state and kinetic downshifting and upconversion photoluminescence spectroscopy. Full article
(This article belongs to the Special Issue Functional Inorganic Materials: Preparation, Characterization and Application)
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12 pages, 6105 KiB  
Article
Novel Ultrafine-Grain Mg-Gd/Nd-Y-Ca Alloys with an Increased Ignition Temperature
by Stanislav Šašek, Peter Minárik, Jitka Stráská, Klára Hosová, Jozef Veselý, Jiří Kubásek, Robert Král, Tomáš Krajňák and Dalibor Vojtěch
Materials 2023, 16(3), 1299; https://doi.org/10.3390/ma16031299 - 3 Feb 2023
Cited by 9 | Viewed by 2595
Abstract
Two novel ignition-resistant magnesium alloys, Mg-2Gd-2Y-1Ca and Mg-2Nd-1Y-1Ca, were prepared in the ultrafine-grain condition by equal channel angular pressing (ECAP). In addition, four commercial alloys—AZ31, AX41, AE42 and WE43—were prepared similarly as a reference. The microstructure, mechanical properties and ignition temperature were thoroughly [...] Read more.
Two novel ignition-resistant magnesium alloys, Mg-2Gd-2Y-1Ca and Mg-2Nd-1Y-1Ca, were prepared in the ultrafine-grain condition by equal channel angular pressing (ECAP). In addition, four commercial alloys—AZ31, AX41, AE42 and WE43—were prepared similarly as a reference. The microstructure, mechanical properties and ignition temperature were thoroughly investigated. Both novel alloys exhibited a mean grain size of ~1 µm and dense distribution of small secondary phase particles. The mechanical strength measured by the tensile deformation test showed that the novel alloys are much stronger (~290 MPa) than all commercial alloys except WE43. However, Ca segregation into the grain boundaries caused a significant decrease in ductility (<6%). The ignition temperature of the novel alloys (~950 °C) was considerably improved by the presence of Gd/Nd, Y and Ca. This study showed that both novel alloys exhibit high strength and high ignition temperature in the ultrafine-grain condition. Full article
(This article belongs to the Section Metals and Alloys)
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14 pages, 6711 KiB  
Article
Thermal Diffusivity of Concrete Samples Assessment Using a Solar Simulator
by Marcin Bilski, Przemysław Górnaś, Andrzej Pożarycki, Przemysław Skrzypczak, Mieczysław Słowik, Marta Mielczarek, Agnieszka Wróblewska and Łukasz Semkło
Materials 2023, 16(3), 1268; https://doi.org/10.3390/ma16031268 - 2 Feb 2023
Cited by 4 | Viewed by 1991
Abstract
The thermal properties of pavement layers made of concrete with varying bulk densities are a particularly interesting topic in the context of development road technologies. If a hybrid layer system is used as a starting point, with thin asphalt layers (from 1 cm [...] Read more.
The thermal properties of pavement layers made of concrete with varying bulk densities are a particularly interesting topic in the context of development road technologies. If a hybrid layer system is used as a starting point, with thin asphalt layers (from 1 cm to 4 cm) laid on top of a foam concrete layer, thermal properties begin to play a crucial role. The main research problem was to create a test method enabling the assessment of the influence of solar heating on the thermal parameters of the building material, especially cement concrete. For this reason, this paper is concerned specifically with the assessment of a new methodology for testing and calculating the value of the thermal diffusivity coefficient of samples made of concrete varying bulk densities. In this case, using the proprietary concept the authors built a solar simulator using a multi-source lighting system. The analysis of the results of laboratory tests and numerical analyses allowed the authors to observe that there is a strong correlation between the bulk density of samples heated and the thermal diffusivity parameter, which appears in the unidirectional heat transfer equation. The strength of this relationship has been expressed with the coefficient of determination and amounts to 99%. The calculated values of the coefficient of thermal diffusivity for samples made of foam concrete range from 0.16×10−6m2s to 0.52×10−6m2s and are lower (from 2.5 to 8 times) than the value determined for samples made of typical cement concrete. Full article
(This article belongs to the Section Construction and Building Materials)
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15 pages, 5074 KiB  
Article
The Influence of Annealing at 500 and 900 °C on the Structure and Mechanical Properties of AlxCoCrFeNi Alloys
by Marzena Tokarewicz, Małgorzata Grądzka-Dahlke, Katarzyna Rećko and Magdalena Łępicka
Materials 2023, 16(3), 1245; https://doi.org/10.3390/ma16031245 - 1 Feb 2023
Cited by 7 | Viewed by 1946
Abstract
The AlCoCrFeNi high-entropy alloy is sensitive to heat treatment. The aim of the present study was to test a similar correlation for AlxCoCrFeNi alloys with less than equimolar aluminum content. This paper presents a study of the annealing effect on the [...] Read more.
The AlCoCrFeNi high-entropy alloy is sensitive to heat treatment. The aim of the present study was to test a similar correlation for AlxCoCrFeNi alloys with less than equimolar aluminum content. This paper presents a study of the annealing effect on the structure and mechanical properties of selected alloys. AlxCoCrFeNi alloys (x = 0, 0.5, 0.7) were fabricated by the induction melting method. The obtained specimens were annealed at 500 °C and 900 °C. A detailed study of the changes in crystalline structure due to annealing was conducted. Three-point bending and hardness tests were carried out for the as-cast and annealed specimens to determine selected mechanical properties. The study confirmed that increasing the aluminum content in the AlxCoCrFeNi alloy improves mechanical properties. For the alloy with aluminum content x = 0.7, hardness increased by 187% and yield strength by 252% compared to the alloy without aluminum. A significant effect of annealing on the crystalline structure of the Al0.7CoCrFeNi alloy was found, but this was not followed by changes in mechanical properties. Full article
(This article belongs to the Special Issue Advanced Materials for Multifunctional Applications)
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11 pages, 4011 KiB  
Article
Short-Term Memory Characteristics of IGZO-Based Three-Terminal Devices
by Juyeong Pyo, Jong-Ho Bae, Sungjun Kim and Seongjae Cho
Materials 2023, 16(3), 1249; https://doi.org/10.3390/ma16031249 - 1 Feb 2023
Cited by 6 | Viewed by 2778
Abstract
A three-terminal synaptic transistor enables more accurate controllability over the conductance compared with traditional two-terminal synaptic devices for the synaptic devices in hardware-oriented neuromorphic systems. In this work, we fabricated IGZO-based three-terminal devices comprising HfAlOx and CeOx layers to demonstrate the [...] Read more.
A three-terminal synaptic transistor enables more accurate controllability over the conductance compared with traditional two-terminal synaptic devices for the synaptic devices in hardware-oriented neuromorphic systems. In this work, we fabricated IGZO-based three-terminal devices comprising HfAlOx and CeOx layers to demonstrate the synaptic operations. The chemical compositions and thicknesses of the devices were verified by transmission electron microscopy and energy dispersive spectroscopy in cooperation. The excitatory post-synaptic current (EPSC), paired-pulse facilitation (PPF), short-term potentiation (STP), and short-term depression (STD) of the synaptic devices were realized for the short-term memory behaviors. The IGZO-based three-terminal synaptic transistor could thus be controlled appropriately by the amplitude, width, and interval time of the pulses for implementing the neuromorphic systems. Full article
(This article belongs to the Special Issue Advances in Conducting and Semiconducting Materials)
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13 pages, 4705 KiB  
Article
Freeze Drying of Polymer Nanoparticles and Liposomes Exploiting Different Saccharide-Based Approaches
by Ilaria Andreana, Valeria Bincoletto, Maela Manzoli, Francesca Rodà, Vita Giarraputo, Paola Milla, Silvia Arpicco and Barbara Stella
Materials 2023, 16(3), 1212; https://doi.org/10.3390/ma16031212 - 31 Jan 2023
Cited by 23 | Viewed by 7038
Abstract
Biodegradable nanocarriers represent promising tools for controlled drug delivery. However, one major drawback related to their use is the long-term stability, which is largely influenced by the presence of water in the formulations, so to solve this problem, freeze-drying with cryoprotectants has been [...] Read more.
Biodegradable nanocarriers represent promising tools for controlled drug delivery. However, one major drawback related to their use is the long-term stability, which is largely influenced by the presence of water in the formulations, so to solve this problem, freeze-drying with cryoprotectants has been proposed. In the present study, the influence of the freeze-drying procedure on the storage stability of poly(lactide-co-glycolide) (PLGA) nanoparticles and liposomes was evaluated. In particular, conventional cryoprotectants were added to PLGA nanoparticle and liposome formulations in various conditions. Additionally, hyaluronic acid (HA), known for its ability to target the CD44 receptor, was assessed as a cryoprotective excipient: it was added to the nanocarriers as either a free molecule or conjugated to a phospholipid to increase the interaction with the polymer or lipid matrix while exposing HA on the nanocarrier surface. The formulations were resuspended and characterized for size, polydispersity index, zeta potential and morphology. It was demonstrated that only the highest percentages of cryoprotectants allowed the resuspension of stable nanocarriers. Moreover, unlike free HA, HA-phospholipid conjugates were able to maintain the particle mean size after the reconstitution of lyophilized nanoparticles and liposomes. This study paves the way for the use of HA-phospholipids to achieve, at the same time, nanocarrier cryoprotection and active targeting. Full article
(This article belongs to the Special Issue Nanomaterials Design towards Biomedical Applications (Volume II))
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21 pages, 5853 KiB  
Article
Physicochemical Modeling of Electrochemical Impedance in Solid-State Supercapacitors
by Davood Peyrow Hedayati, Gita Singh, Michael Kucher, Tony D. Keene and Robert Böhm
Materials 2023, 16(3), 1232; https://doi.org/10.3390/ma16031232 - 31 Jan 2023
Cited by 9 | Viewed by 4073
Abstract
Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving [...] Read more.
Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving their performance. To this end, a conventional mathematical and a physicochemical model were adapted. The impedance was measured by electrochemical impedance spectroscopy (EIS). An EC consisting of electrical elements was introduced for each modeling approach. The mathematical model was purely based on a best-fit method and utilized an EC with intuitive elements. In contrast, the physicochemical model was motivated by advanced theories and allowed meaningful associations with properties at the electrode, the electrolyte, and their interface. The physicochemical model showed a higher approximation ability (relative error of 3.7%) due to the interface impedance integration in a more complex circuit design. However, this model required more modeling and optimization effort. Moreover, the fitted parameters differed from the analytically calculated ones due to uncertainties in the SSC’s microscale configuration, which need further investigations. Nevertheless, the results show that the proposed physicochemical model is promising in simulating EIS data of SSCs with the additional advantage of utilizing well-reasoned property-based EC elements. Full article
(This article belongs to the Special Issue New-Generation Advanced Materials for Next-Generation Supercapacitors)
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12 pages, 2797 KiB  
Article
Polarization Doping in a GaN-InN System—Ab Initio Simulation
by Ashfaq Ahmad, Pawel Strak, Pawel Kempisty, Konrad Sakowski, Jacek Piechota, Yoshihiro Kangawa, Izabella Grzegory, Michal Leszczynski, Zbigniew R. Zytkiewicz, Grzegorz Muziol, Eva Monroy, Agata Kaminska and Stanislaw Krukowski
Materials 2023, 16(3), 1227; https://doi.org/10.3390/ma16031227 - 31 Jan 2023
Viewed by 2612
Abstract
Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that [...] Read more.
Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that it could be obtained from a polarization difference and the concentration slope. It was shown that the GaN-InN polarization difference is changed by piezoelectric effects. The polarization difference is in agreement with the earlier obtained data despite the relatively narrow bandgap for the simulated system. The hole generation may be applied in the design of blue and green laser and light-emitting diodes. Full article
(This article belongs to the Special Issue III-V Semiconductor Optoelectronics: Materials and Devices)
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18 pages, 2394 KiB  
Article
The Morphology, Mechanical and Dynamic Properties, Fire Hazard and Toxicity of Chloroprene and Butadiene Rubber Composites Cross-Linked with Zinc
by Aleksandra Smejda-Krzewicka, Przemysław Rybiński, Dariusz Bradło and Witold Żukowski
Materials 2023, 16(3), 1240; https://doi.org/10.3390/ma16031240 - 31 Jan 2023
Cited by 5 | Viewed by 2061
Abstract
This paper presents the influence of zinc on the cross-linking process, mechanical and dynamic properties, morphologies and balance of thermal degradation of blends containing chloroprene rubber (CR) and butadiene rubber (BR). The novel aspect of this research is a comprehensive approach presenting a [...] Read more.
This paper presents the influence of zinc on the cross-linking process, mechanical and dynamic properties, morphologies and balance of thermal degradation of blends containing chloroprene rubber (CR) and butadiene rubber (BR). The novel aspect of this research is a comprehensive approach presenting a new curing agent for the CR/BR blends to increase their cross-linking density and final properties, including non-flammability and low fire hazard. This is due to the need to find an alternative to zinc oxide, which is the standard curing agent for chloroprene rubber. The regulations of the European Union enforce a significant limitation on the use of this compound in elastomer technology, due to its harmful effect on aquatic organisms. In this paper, the CR/BR composites were cured with zinc and filled with natural silica fillers (sillitin or chalcedonite) or synthetic silica filler (aerosil). The investigation focused on the morphology characterization of the obtained compounds, their cross-linking degree, swelling, mechanical and dynamic properties, fire hazard and toxicity. The structure of cured CR/BR blends was characterized via scanning electron microscopy (SEM). The fire resistance studies were performed using cone calorimetry or oxygen index methods, whereas toxicity tests were performed with the use of the FB-FTIR (fluidized bed reactor coupled with FTIR analyzer) method. The results showed that obtained CR/BR products were characterized by satisfactory final properties. The properties determined by the oxygen index and cone calorimetry methods, including the behaviors of the tested CR/BR vulcanizates in fire conditions, showed that the produced compounds were characterized by a low fire hazard and can be classified as non-combustible rubber products. However, the toxicity of the decomposition products, determined at 450, 550 and 750 °C, was very high. Full article
(This article belongs to the Special Issue Morphology, Flammability, Thermal and Mechanical Properties of Polymer Composites)
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14 pages, 18830 KiB  
Article
MoS2/Au Heterojunction Catalyst for SERS Monitoring of a Fenton-like Reaction
by Qian Wei, Beibei Lu, Qing Yang, Can Shi, Yulan Wei, Minmin Xu, Chenjie Zhang and Yaxian Yuan
Materials 2023, 16(3), 1169; https://doi.org/10.3390/ma16031169 - 30 Jan 2023
Viewed by 2650
Abstract
Fenton technology is one of advanced oxidation process (AOP) methods to treat wastewater through chemical oxidation. Due to the limitations of classical iron-based catalysts, it is still challenging to find suitable catalysts for Fenton-like reactions. Here, MoS2/Au heterojunctions were successfully synthesized [...] Read more.
Fenton technology is one of advanced oxidation process (AOP) methods to treat wastewater through chemical oxidation. Due to the limitations of classical iron-based catalysts, it is still challenging to find suitable catalysts for Fenton-like reactions. Here, MoS2/Au heterojunctions were successfully synthesized by reduction of chloroauric acid in the solution of layered MoS2 prepared by hydrothermal method. As a model molecule, methylene blue (MB) was used as the species to be degraded to evaluate the performance of the catalyst. It was determined by UV–visible spectra that the optimal catalyst can be obtained when MoS2 (mg): HAuCl4 (wt. % mL) is 2:2. The Fenton-like reaction process was monitored by introducing highly sensitive surface enhanced Raman spectroscopy (SERS). The results show that MB can be degraded by 83% in the first 10 min of the reaction, indicating that MoS2/Au has good catalytic performance. In addition, as a fingerprint spectrum, SERS was used to preliminarily analyze the molecular structure changes during the degradation process. The result showed that C-N-C bond was easier to break than the C-S-C bond. NH2 group and the fused ring were destroyed at the comparable speed at the first 30 min. In terms of application applicability, it was showed that MB degradation had exceeded 95% at all the three pH values of 1.4, 5.0, and 11.1 after the reaction was carried out for 20 min. The test and analysis of the light environment showed that the catalytic efficiency was significantly improved in the natural light of the laboratory compared to dark conditions. The possible mechanism based on ·OH and ·O2− from ESR data was proposed. In addition, it was demonstrated to be a first-order reaction from the perspective of kinetics. This study made a positive contribution to broaden of the applicable conditions and scope of Fenton-like reaction catalysts. It is expected to be used as a non-iron catalyst in practical industrial applications. From the perspective of detection method, we expect to develop SERS as a powerful tool for the in situ monitoring of Fenton-like reactions, and to further deepen our understanding of the mechanism. Full article
(This article belongs to the Special Issue Advanced Photocatalytic Material: Synthesis, Characterization and Application)
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19 pages, 7258 KiB  
Article
Reinforcement Corrosion Testing in Concrete and Fiber Reinforced Concrete Specimens Exposed to Aggressive External Factors
by Wioletta Raczkiewicz, Magdalena Bacharz, Kamil Bacharz and Michał Teodorczyk
Materials 2023, 16(3), 1174; https://doi.org/10.3390/ma16031174 - 30 Jan 2023
Cited by 9 | Viewed by 3212
Abstract
One of the leading causes of reinforced concrete degradation is chloride attack. It occurs due to the penetration of chlorides through pores and cracks into the concrete cover. This phenomenon becomes more dangerous if reinforced concrete elements are subjected to cyclic temperature changes. [...] Read more.
One of the leading causes of reinforced concrete degradation is chloride attack. It occurs due to the penetration of chlorides through pores and cracks into the concrete cover. This phenomenon becomes more dangerous if reinforced concrete elements are subjected to cyclic temperature changes. The concrete cover protects against corrosion. This paper presents research, the primary purpose of which was to determine the effect of the addition of steel fibers to concrete on the development of corrosion of the main reinforcement. The tests were carried out on three types of reinforced concrete specimens made of ordinary concrete and concrete with different amounts of steel fibers (0.25% and 0.50%). In order to initiate corrosion processes, specimens were partially submerged in a 3% sodium chloride solution and were subjected to freeze–thaw cycles. The electrochemical polarization galvanostatic pulse method was used for analyzing the reinforcement corrosion activity. Moreover, it was verified whether the corrosion of reinforced concrete elements affects the acoustic emission wave velocity. The addition of steel micro-reinforcement fibers increases the corrosion resistance of reinforced concrete. In addition, a strong linear correlation between the AE wave velocity and the values of the corrosion current density was revealed. Full article
(This article belongs to the Special Issue Corrosion of Materials: Evaluation, Testing, Protection, and Failure Analysis)
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24 pages, 3728 KiB  
Article
Effects of Altering Magnesium Metal Surfaces on Degradation In Vitro and In Vivo during Peripheral Nerve Regeneration
by Rigwed Tatu, Leon G. White, Yeoheung Yun, Tracy Hopkins, Xiaoxian An, Ahmed Ashraf, Kevin J. Little, Meir Hershcovitch, David B. Hom and Sarah Pixley
Materials 2023, 16(3), 1195; https://doi.org/10.3390/ma16031195 - 30 Jan 2023
Cited by 4 | Viewed by 2939
Abstract
In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We [...] Read more.
In vivo use of biodegradable magnesium (Mg) metal can be plagued by too rapid a degradation rate that removes metal support before physiological function is repaired. To advance the use of Mg biomedical implants, the degradation rate may need to be adjusted. We previously demonstrated that pure Mg filaments used in a nerve repair scaffold were compatible with regenerating peripheral nerve tissues, reduced inflammation, and improved axonal numbers across a short—but not long—gap in sciatic nerves in rats. To determine if the repair of longer gaps would be improved by a slower Mg degradation rate, we tested, in vitro and in vivo, the effects of Mg filament polishing followed by anodization using plasma electrolytic oxidation (PEO) with non-toxic electrolytes. Polishing removed oxidation products from the surface of as-received (unpolished) filaments, exposed more Mg on the surface, produced a smoother surface, slowed in vitro Mg degradation over four weeks after immersion in a physiological solution, and improved attachment of cultured epithelial cells. In vivo, treated Mg filaments were used to repair longer (15 mm) injury gaps in adult rat sciatic nerves after placement inside hollow poly (caprolactone) nerve conduits. The addition of single Mg or control titanium filaments was compared to empty conduits (negative control) and isografts (nerves from donor rats, positive control). After six weeks in vivo, live animal imaging with micro computed tomography (micro-CT) showed that Mg metal degradation rates were slowed by polishing vs. as-received Mg, but not by anodization, which introduced greater variability. After 14 weeks in vivo, functional return was seen only with isograft controls. However, within Mg filament groups, the amount of axonal growth across the injury site was improved with slower Mg degradation rates. Thus, anodization slowed degradation in vitro but not in vivo, and degradation rates do affect nerve regeneration. Full article
(This article belongs to the Special Issue Magnesium and Its Alloys as Biodegradable Implants)
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16 pages, 2471 KiB  
Article
Phenolic Compounds Removal from Olive Mill Wastewater Using the Composite of Activated Carbon and Copper-Based Metal-Organic Framework
by Muna A. Abu-Dalo, Nathir A. F. Al-Rawashdeh, Moath Almurabi, Jehad Abdelnabi and Abeer Al Bawab
Materials 2023, 16(3), 1159; https://doi.org/10.3390/ma16031159 - 29 Jan 2023
Cited by 9 | Viewed by 3221
Abstract
As the industry of olive oil continues to grow, the management of olive mill wastewater (OMW) by-products has become an area of great interest. While many strategies for processing OMW have been established, more studies are still required to find an effective adsorbent [...] Read more.
As the industry of olive oil continues to grow, the management of olive mill wastewater (OMW) by-products has become an area of great interest. While many strategies for processing OMW have been established, more studies are still required to find an effective adsorbent for total phenolic content uptake. Here, we present a composite of a Cu 1,4-benzene dicarboxylate metal-organic framework (Cu (BDC) MOF) and granular activated carbon (GAC) as an adsorbent for total phenolic content removal from OMW. Experimental results demonstrated that the maximum adsorption capacity was 20 mg/g of total phenolic content (TPC) after 4 h. using 2% wt/wt of GAC/Cu (BDC) MOF composite to OMW at optimum conditions (pH of 4.0 and 25 °C). The adsorption of phenolic content onto the GAC/Cu (BDC) MOF composite was described by the Freundlich adsorption and pseudo-second-order reaction. The adsorption reaction was found to be spontaneous and endothermic at 298 K where ΔS° and ΔH° were found to be 0.105 KJ/mol and 25.7 kJ/mol, respectively. While ΔGº value was −5.74 (kJ/mol). The results of this study provide a potential solution for the local and worldwide olive oil industry. Full article
(This article belongs to the Special Issue Recent Progress in Advanced Adsorption Materials)
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24 pages, 5042 KiB  
Article
Burdock-Derived Composites Based on Biogenic Gold, Silver Chloride and Zinc Oxide Particles as Green Multifunctional Platforms for Biomedical Applications and Environmental Protection
by Irina Zgura, Nicoleta Badea, Monica Enculescu, Valentin-Adrian Maraloiu, Camelia Ungureanu and Marcela-Elisabeta Barbinta-Patrascu
Materials 2023, 16(3), 1153; https://doi.org/10.3390/ma16031153 - 29 Jan 2023
Cited by 8 | Viewed by 3205
Abstract
Green nanotechnology is a rapidly growing field linked to using the principles of green chemistry to design novel nanomaterials with great potential in environmental and health protection. In this work, metal and semiconducting particles (AuNPs, AgClNPs, ZnO, AuZnO, AgClZnO, and AuAgClZnO) were phytosynthesized [...] Read more.
Green nanotechnology is a rapidly growing field linked to using the principles of green chemistry to design novel nanomaterials with great potential in environmental and health protection. In this work, metal and semiconducting particles (AuNPs, AgClNPs, ZnO, AuZnO, AgClZnO, and AuAgClZnO) were phytosynthesized through a “green” bottom-up approach, using burdock (Arctium lappa L.) aqueous extract. The morphological (SEM/TEM), structural (XRD, SAED), compositional (EDS), optical (UV–Vis absorption and FTIR spectroscopy), photocatalytic, and bio-properties of the prepared composites were analyzed. The particle size was determined by SEM/TEM and by DLS measurements. The phytoparticles presented high and moderate physical stability, evaluated by zeta potential measurements. The investigation of photocatalytic activity of these composites, using Rhodamine B solutions’ degradation under solar light irradiation in the presence of prepared powders, showed different degradation efficiencies. Bioevaluation of the obtained composites revealed the antioxidant and antibacterial properties. The tricomponent system AuAgClZnO showed the best antioxidant activity for capturing ROS and ABTS•+ radicals, and the best biocidal action against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The “green” developed composites can be considered potential adjuvants in biomedical (antioxidant or biocidal agents) or environmental (as antimicrobial agents and catalysts for degradation of water pollutants) applications. Full article
(This article belongs to the Special Issue Novel Green Nanotechnologies Applied in Environmental Protection and Health)
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15 pages, 3009 KiB  
Article
ZGSO Spinel Nanoparticles with Dual Emission of NIR Persistent Luminescence for Anti-Counterfeiting Applications
by Guanyu Cai, Teresa Delgado, Cyrille Richard and Bruno Viana
Materials 2023, 16(3), 1132; https://doi.org/10.3390/ma16031132 - 28 Jan 2023
Cited by 35 | Viewed by 4297
Abstract
The property of persistent luminescence shows great potential for anti-counterfeiting technology and imaging by taking advantage of a background-free signal. Current anti-counterfeiting technologies face the challenge of low security and the inconvenience of being limited to visible light emission, as emitters in the [...] Read more.
The property of persistent luminescence shows great potential for anti-counterfeiting technology and imaging by taking advantage of a background-free signal. Current anti-counterfeiting technologies face the challenge of low security and the inconvenience of being limited to visible light emission, as emitters in the NIR optical windows are required for such applications. Here, we report the preparation of a series of Zn1+xGa2−2xSnxO4 nanoparticles (ZGSO NPs) with persistent luminescence in the first and second near-infrared window to overcome these challenges. ZGSO NPs, doped with transition-metal (Cr3+ and/or Ni2+) and in some cases co-doped with rare-earth (Er3+) ions, were successfully prepared using an improved solid-state method with a subsequent milling process to reach sub-200 nm size particles. X-ray diffraction and absorption spectroscopy were used for the analysis of the structure and local crystal field around the dopant ions at different Sn4+/Ga3+ ratios. The size of the NPs was ~150 nm, measured by DLS. Doped ZGSO NPs exhibited intense photoluminescence in the range from red, NIR-I to NIR-II, and even NIR-III, under UV radiation, and showed persistent luminescence at 700 nm (NIR-I) and 1300 nm (NIR-II) after excitation removal. Hence, these NPs were evaluated for multi-level anti-counterfeiting technology. Full article
(This article belongs to the Special Issue Advanced Luminescent Materials and Devices)
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13 pages, 2416 KiB  
Article
Carbon Quantum Dots Accelerating Surface Charge Transfer of 3D PbBiO2I Microspheres with Enhanced Broad Spectrum Photocatalytic Activity—Development and Mechanism Insight
by Ruyu Yan, Xinyi Liu, Haijie Zhang, Meng Ye, Zhenxing Wang, Jianjian Yi, Binxian Gu and Qingsong Hu
Materials 2023, 16(3), 1111; https://doi.org/10.3390/ma16031111 - 27 Jan 2023
Cited by 5 | Viewed by 2648
Abstract
The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) [...] Read more.
The development of a highly efficient, visible-light responsive catalyst for environment purification has been a long-standing exploit, with obstacles to overcome, including inefficient capture of near-infrared photons, undesirable recombination of photo-generated carriers, and insufficient accessible reaction sites. Hence, novel carbon quantum dots (CQDs) modified PbBiO2I photocatalyst were synthesized for the first time through an in-situ ionic liquid-induced method. The bridging function of 1-butyl-3-methylimidazolium iodide ([Bmim]I) guarantees the even dispersion of CQDs around PbBiO2I surface, for synchronically overcoming the above drawbacks and markedly promoting the degradation efficiency of organic contaminants: (i) CQDs decoration harness solar photons in the near-infrared region; (ii) particular delocalized conjugated construction of CQDs strength via the utilization of photo-induced carriers; (iii) π–π interactions increase the contact between catalyst and organic molecules. Benefiting from these distinguished features, the optimized CQDs/PbBiO2I nanocomposite displays significantly enhanced photocatalytic performance towards the elimination of rhodamine B and ciprofloxacin under visible/near-infrared light irradiation. The spin-trapping ESR analysis demonstrates that CQDs modification can boost the concentration of reactive oxygen species (O2•−). Combined with radicals trapping tests, valence-band spectra, and Mott–Schottky results, a possible photocatalytic mechanism is proposed. This work establishes a significant milestone in constructing CQDs-modified, bismuth-based catalysts for solar energy conversion applications. Full article
(This article belongs to the Special Issue Advanced Photocatalytic Materials for Environmental and Energy Applications)
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14 pages, 3616 KiB  
Article
Raclopride-Molecularly Imprinted Polymers: A Promising Technology for Selective [11C]Raclopride Purification
by Roberta Del Sole, Giancarlo Pascali, Giuseppe Mele, Gary Perkins and Lucia Mergola
Materials 2023, 16(3), 1091; https://doi.org/10.3390/ma16031091 - 27 Jan 2023
Viewed by 1808
Abstract
In this work, we developed a novel approach to purify [11C]Raclopride ([11C]RAC), an important positron emission tomography radiotracer, based on tailored shape-recognition polymers, with the aim to substitute single-pass HPLC purification with an in-flow trap & release process. Molecular [...] Read more.
In this work, we developed a novel approach to purify [11C]Raclopride ([11C]RAC), an important positron emission tomography radiotracer, based on tailored shape-recognition polymers, with the aim to substitute single-pass HPLC purification with an in-flow trap & release process. Molecular imprinting technology (MIT) applied to solid phase extraction (MISPE) was investigated to develop a setting able to selectively extract [11C]RAC in a mixture containing a high amount of its precursor, (S)-O-Des-Methyl-Raclopride (DM-RAC). Two imprinted polymers selective for unlabeled RAC and DM-RAC were synthesized through a radical polymerization at 65 °C using methacrylic acid and trimethylolpropane trimethacrylate in the presence of template molecule (RAC or DM-RAC). The prepared polymer was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy and tested in MISPE experiments. The polymers were used in testing conditions, revealing a high retention capacity of RAC-MISPE to retain RAC either in the presence of similar concentrations of RAC and DM-RAC precursor (96.9%, RSD 6.6%) and in the presence of a large excess of precursor (90%, RSD 4.6%) in the loading solution. Starting from these promising results, preliminary studies for selective purification of [11C]Raclopride using this RAC-MISPE were performed and, while generally confirming the selectivity capacity of the polymer, revealed challenging applicability to the current synthetic process, mainly due to high backpressures and long elution times. Full article
(This article belongs to the Section Materials Chemistry)
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17 pages, 10804 KiB  
Article
Effect of Polydopamine Coating of Cellulose Nanocrystals on Performance of PCL/PLA Bio-Nanocomposites
by Ivan Kelnar, Ludmila Kaprálková, Sabina Krejčíková, Jiří Dybal, Michaela Vyroubalová and A. M. Abdel-Mohsen
Materials 2023, 16(3), 1087; https://doi.org/10.3390/ma16031087 - 27 Jan 2023
Cited by 4 | Viewed by 2373
Abstract
In bio-nanocomposites with a poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) matrix with neat and polydopamine (PDA)-coated cellulose nanocrystals (CNCd), the use of different mixing protocols with masterbatches prepared by solution casting led to marked variation of localization, as well as reinforcing and structure-directing effects, of [...] Read more.
In bio-nanocomposites with a poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) matrix with neat and polydopamine (PDA)-coated cellulose nanocrystals (CNCd), the use of different mixing protocols with masterbatches prepared by solution casting led to marked variation of localization, as well as reinforcing and structure-directing effects, of cellulose nanocrystals (CNC). The most balanced mechanical properties were found with an 80/20 PLA/PCL ratio, and complex PCL/CNC structures were formed. In the nanocomposites with a bicontinuous structure (60/40 and 40/60 PLA/PCL ratios), pre-blending the CNC and CNCd/PLA caused a marked increase in the continuity of mechanically stronger PLA and an improvement in related parameters of the system. On the other hand, improved continuity of the PCL phase when using a PCL masterbatch may lead to the reduction in or elimination of reinforcing effects. The PDA coating of CNC significantly changed its behavior. In particular, a higher affinity to PCL and ordering of PLA led to dissimilar structures and interface transformations, while also having antagonistic effects on mechanical properties. The negligible differences in bulk crystallinity indicate that alteration of mechanical properties may have originated from differences in crystallinity at the interface, also influenced by presence of CNC in this area. The complex effect of CNC on bio-nanocomposites, including the potential of PDA coating to increase thermal stability, is worthy of further study. Full article
(This article belongs to the Special Issue Advanced Polymeric Materials: Synthesis, Properties, and Applications)
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10 pages, 20760 KiB  
Article
Enhanced Optical and Electronic Properties of Silicon Nanosheets by Phosphorus Doping Passivation
by Ye Lei, Deren Yang and Dongsheng Li
Materials 2023, 16(3), 1079; https://doi.org/10.3390/ma16031079 - 26 Jan 2023
Cited by 2 | Viewed by 2197
Abstract
In this paper, we use the spin-on-dopant technique for phosphorus doping to improve the photoelectric properties of soft-chemical-prepared silicon nanosheets. It was found that the luminescence intensity and luminescence lifetime of the doped samples was approximately 4 fold that of the undoped samples, [...] Read more.
In this paper, we use the spin-on-dopant technique for phosphorus doping to improve the photoelectric properties of soft-chemical-prepared silicon nanosheets. It was found that the luminescence intensity and luminescence lifetime of the doped samples was approximately 4 fold that of the undoped samples, due to passivation of the surface defects by phosphorus doping. Meanwhile, phosphorus doping combined with high-temperature heat treatment can reduce the resistivity of multilayer silicon nanosheets by 6 fold compared with that of as-prepared samples. In conclusion, our work brings soft-chemical-prepared silicon nanosheets one step closer to practical application in the field of optoelectronics. Full article
(This article belongs to the Section Advanced Nanomaterials and Nanotechnology)
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29 pages, 3912 KiB  
Review
Ongoing Challenges of Laser-Based Powder Bed Fusion Processing of Al Alloys and Potential Solutions from the Literature—A Review
by Alessandra Martucci, Alberta Aversa and Mariangela Lombardi
Materials 2023, 16(3), 1084; https://doi.org/10.3390/ma16031084 - 26 Jan 2023
Cited by 35 | Viewed by 6507
Abstract
Their high strength-to-weight ratio, good corrosion resistance and excellent thermal and electrical conductivity have exponentially increased the interest in aluminium alloys in the context of laser-based powder bed fusion (PBF-LB/M) production. Although Al-based alloys are the third most investigated category of alloys in [...] Read more.
Their high strength-to-weight ratio, good corrosion resistance and excellent thermal and electrical conductivity have exponentially increased the interest in aluminium alloys in the context of laser-based powder bed fusion (PBF-LB/M) production. Although Al-based alloys are the third most investigated category of alloys in the literature and the second most used in industry, their processing by PBF-LB/M is often hampered by their considerable solidification shrinkage, tendency to oxidation, high laser reflectivity and poor powder flowability. For these reasons, high-strength Al-based alloys traditionally processed by conventional procedures have often proved to be unprintable with additive technology, so the design and development of new tailored Al-based alloys for PBF-LB/M production is necessary. The aim of the present work is to explore all the challenges encountered before, during and after the PBF-LB/M processing of Al-based alloys, in order to critically analyse the solutions proposed in the literature and suggest new approaches for addressing unsolved problems. The analysis covers the critical aspects in the literature as well as industrial needs, industrial patents published to date and possible future developments in the additive market. Full article
(This article belongs to the Special Issue Microstructure and Mechanical Properties of Laser Additive Manufactured Metals II)
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12 pages, 6387 KiB  
Article
Enhanced Surface Properties of the Al0.65CoCrFeNi High-Entropy Alloy via Laser Remelting
by Junwei Miao, Tianxin Li, Qiang Li, Xiaohu Chen, Zheng Ren and Yiping Lu
Materials 2023, 16(3), 1085; https://doi.org/10.3390/ma16031085 - 26 Jan 2023
Cited by 16 | Viewed by 2336
Abstract
The laser remelting technique was applied to the surface modification of the Al0.65CoCrFeNi high-entropy alloy (HEA) to further advance its mechanical potential. The microstructure of the remelted layer was refined from coarse dendritic to submicron-scale basket weave compared with the as-cast [...] Read more.
The laser remelting technique was applied to the surface modification of the Al0.65CoCrFeNi high-entropy alloy (HEA) to further advance its mechanical potential. The microstructure of the remelted layer was refined from coarse dendritic to submicron-scale basket weave compared with the as-cast substrate, resulting in a 1.8-time increase in Vickers microhardness. The nanoindentation tests indicated that the nanohardness of the remelted layer was higher than that of each phase in the substrate. Meanwhile, the remelted layer retained considerable plasticity, as evidenced by its high Wp/Wt ratio (0.763) and strain hardening exponent (0.302). Additionally, adhesive wear prevailed on the substrate, while only abrasive wear features were observed on the remelted layer. Accordingly, the average friction coefficient and the wear rate of the remelted layer were minimized by 23% and 80%, respectively, compared with the substrate. Our findings explored an industrialized method to enhance the surface properties of the Al0.65CoCrFeNi HEA and also provided some helpful references for its laser additive manufacturing. Full article
(This article belongs to the Special Issue New Functional Materials with Cavitation-Erosion Resistance)
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18 pages, 3615 KiB  
Review
Research Progress on Multi-Component Alloying and Heat Treatment of High Strength and Toughness Al–Si–Cu–Mg Cast Aluminum Alloys
by Mingshan Zhang, Yaqiang Tian, Xiaoping Zheng, Yuan Zhang, Liansheng Chen and Junsheng Wang
Materials 2023, 16(3), 1065; https://doi.org/10.3390/ma16031065 - 25 Jan 2023
Cited by 40 | Viewed by 4937
Abstract
Al–Si–Cu–Mg cast aluminum alloys have important applications in automobile lightweight due to their advantages such as high strength-to-weight ratio, good heat resistance and excellent casting performance. With the increasing demand for strength and toughness of automotive parts, the development of high strength and [...] Read more.
Al–Si–Cu–Mg cast aluminum alloys have important applications in automobile lightweight due to their advantages such as high strength-to-weight ratio, good heat resistance and excellent casting performance. With the increasing demand for strength and toughness of automotive parts, the development of high strength and toughness Al–Si–Cu–Mg cast aluminum alloys is one of the effective measures to promote the application of cast aluminum alloys in the automotive industry. In this paper, the research progress of improving the strength and toughness of Al–Si–Cu–Mg cast aluminum alloys was described from the aspects of multi-component alloying and heat treatment based on the strengthening mechanism of Al–Si–Cu–Mg cast aluminum alloys. Finally, the development prospects of automotive lightweight Al–Si–Cu–Mg cast aluminum alloys is presented. Full article
(This article belongs to the Special Issue Heat Treatments and Performance of Alloy and Metal)
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16 pages, 5120 KiB  
Article
Nanolithographic Fabrication Technologies for Network-Based Biocomputation Devices
by Christoph R. Meinecke, Georg Heldt, Thomas Blaudeck, Frida W. Lindberg, Falco C. M. J. M. van Delft, Mohammad Ashikur Rahman, Aseem Salhotra, Alf Månsson, Heiner Linke, Till Korten, Stefan Diez, Danny Reuter and Stefan E. Schulz
Materials 2023, 16(3), 1046; https://doi.org/10.3390/ma16031046 - 24 Jan 2023
Cited by 4 | Viewed by 2438
Abstract
Network-based biocomputation (NBC) relies on accurate guiding of biological agents through nanofabricated channels produced by lithographic patterning techniques. Here, we report on the large-scale, wafer-level fabrication of optimized microfluidic channel networks (NBC networks) using electron-beam lithography as the central method. To confirm the [...] Read more.
Network-based biocomputation (NBC) relies on accurate guiding of biological agents through nanofabricated channels produced by lithographic patterning techniques. Here, we report on the large-scale, wafer-level fabrication of optimized microfluidic channel networks (NBC networks) using electron-beam lithography as the central method. To confirm the functionality of these NBC networks, we solve an instance of a classical non-deterministic-polynomial-time complete (“NP-complete”) problem, the subset-sum problem. The propagation of cytoskeletal filaments, e.g., molecular motor-propelled microtubules or actin filaments, relies on a combination of physical and chemical guiding along the channels of an NBC network. Therefore, the nanofabricated channels have to fulfill specific requirements with respect to the biochemical treatment as well as the geometrical confienement, with walls surrounding the floors where functional molecular motors attach. We show how the material stack used for the NBC network can be optimized so that the motor-proteins attach themselves in functional form only to the floor of the channels. Further optimizations in the nanolithographic fabrication processes greatly improve the smoothness of the channel walls and floors, while optimizations in motor-protein expression and purification improve the activity of the motor proteins, and therefore, the motility of the filaments. Together, these optimizations provide us with the opportunity to increase the reliability of our NBC devices. In the future, we expect that these nanolithographic fabrication technologies will enable production of large-scale NBC networks intended to solve substantially larger combinatorial problems that are currently outside the capabilities of conventional software-based solvers. Full article
(This article belongs to the Special Issue Lithography: Materials, Processes and Applications)
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13 pages, 5967 KiB  
Article
Evaluation of the Influence of Grain Sizes of Nanostructured WO3 Ceramics on the Resistance to Radiation-Induced Softening
by Dauren B. Kadyrzhanov, Artem L. Kozlovskiy, Maxim V. Zdorovets, Inesh E. Kenzhina and Dmitriy I. Shlimas
Materials 2023, 16(3), 1028; https://doi.org/10.3390/ma16031028 - 23 Jan 2023
Cited by 2 | Viewed by 1700
Abstract
The main purpose of this study is to test a hypothesis about the effect of grain size on the resistance to destruction and changes in the strength and mechanical properties of oxide ceramics subjected to irradiation. WO3 powders were chosen as objects [...] Read more.
The main purpose of this study is to test a hypothesis about the effect of grain size on the resistance to destruction and changes in the strength and mechanical properties of oxide ceramics subjected to irradiation. WO3 powders were chosen as objects of study, which have a number of unique properties that meet the requirements for their use as a basis for inert matrices of dispersed nuclear fuel. The grain-size variation in WO3 ceramics was investigated by mechanochemical grinding of powders with different grinding speeds. Grinding conditions were experimentally selected to obtain powders with a high degree of size homogeneity, which were used for further research. During evaluation of the strength properties, it was found that a decrease in the grain size leads to an increase in the crack resistance, as well as the hardness of ceramics. The increase in strength properties can be explained by an increase in the dislocation density and the volume contribution of grain boundaries, which lead to hardening and an increase in resistance. During determination of the radiation damage resistance, it was found that a decrease in grain size to 50–70 nm leads to a decrease in the degree of radiation damage and the preservation of the resistance of irradiated ceramics to destruction and cracking. Full article
(This article belongs to the Special Issue Advances in Transparent Ceramics and Composites)
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14 pages, 2085 KiB  
Article
Numerical Modelling of the Constitutive Behaviour of FRCM Composites through the Use of Truss Elements
by Maria Concetta Oddo, Giovanni Minafó, Marielisa Di Leto and Lidia La Mendola
Materials 2023, 16(3), 1011; https://doi.org/10.3390/ma16031011 - 22 Jan 2023
Cited by 3 | Viewed by 2119
Abstract
The modeling of the mechanical behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites is a difficult task due to the complex mechanisms established at the fibre-matrix and composite-support interface level. Recently, several modeling approaches have been proposed to simulate the mechanical response of [...] Read more.
The modeling of the mechanical behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites is a difficult task due to the complex mechanisms established at the fibre-matrix and composite-support interface level. Recently, several modeling approaches have been proposed to simulate the mechanical response of FRCM strengthening systems, however a simple and reliable procedure is still missing. In this paper, two simplified numerical models are proposed to simulate the tensile and shear bond behavior of FRCM composites. Both models take advantage of truss and non-linear spring elements to simulate the material components and the interface. The proposed approach enables us to deduce the global mechanical response in terms of stress-strain or stress-slip relations. The accuracy of the proposed models is validated against the experimental benchmarks available in the literature. Full article
(This article belongs to the Special Issue Advances in Sustainable Inorganic Matrix Composites for Construction)
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29 pages, 8956 KiB  
Review
Novel Photonic Applications of Silicon Carbide
by Haiyan Ou, Xiaodong Shi, Yaoqin Lu, Manuel Kollmuss, Johannes Steiner, Vincent Tabouret, Mikael Syväjärvi, Peter Wellmann and Didier Chaussende
Materials 2023, 16(3), 1014; https://doi.org/10.3390/ma16031014 - 22 Jan 2023
Cited by 35 | Viewed by 8235
Abstract
Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. [...] Read more.
Silicon carbide (SiC) is emerging rapidly in novel photonic applications thanks to its unique photonic properties facilitated by the advances of nanotechnologies such as nanofabrication and nanofilm transfer. This review paper will start with the introduction of exceptional optical properties of silicon carbide. Then, a key structure, i.e., silicon carbide on insulator stack (SiCOI), is discussed which lays solid fundament for tight light confinement and strong light-SiC interaction in high quality factor and low volume optical cavities. As examples, microring resonator, microdisk and photonic crystal cavities are summarized in terms of quality (Q) factor, volume and polytypes. A main challenge for SiC photonic application is complementary metal-oxide-semiconductor (CMOS) compatibility and low-loss material growth. The state-of-the-art SiC with different polytypes and growth methods are reviewed and a roadmap for the loss reduction is predicted for photonic applications. Combining the fact that SiC possesses many different color centers with the SiCOI platform, SiC is also deemed to be a very competitive platform for future quantum photonic integrated circuit applications. Its perspectives and potential impacts are included at the end of this review paper. Full article
(This article belongs to the Special Issue Silicon Carbide: Material Growth, Device Processing and Applications)
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13 pages, 7560 KiB  
Article
Improving the p-Type CuCrO2 Thin Film’s Electrical and Optical Properties
by Jiaxin Jiang, Yu-Feng You, Dhanapal Vasu, Sheng-Chi Chen, Te-Wei Chiu, Gopi Prashanth and Po Chou Chen
Materials 2023, 16(3), 1000; https://doi.org/10.3390/ma16031000 - 21 Jan 2023
Cited by 2 | Viewed by 3153
Abstract
In this research, we studied the functional properties of CuCrO2, which is the most promising p-type transparent conductive oxide (TCO). The thin films were fabricated using a spin coating technique. The diffraction patterns were obtained with the help of X-ray diffractions, [...] Read more.
In this research, we studied the functional properties of CuCrO2, which is the most promising p-type transparent conductive oxide (TCO). The thin films were fabricated using a spin coating technique. The diffraction patterns were obtained with the help of X-ray diffractions, and the optical properties of absorption characteristics were studied using UV-visible absorption. The physical properties of film formation and surface morphology were analyzed using FESEM analysis. The aging properties were also analyzed with the help of various precursors with different aging times. The CuCrO2 thin films’ functional properties were determined by using chelating agent and precursor solution aging times. The CuCrO2 thin films have better transmittance, resistance, figure of merit (FOM), and electrical conductivity. Moreover, the resistivity values of the CuCrO2 thin films are 7.01, 9.90, 12.54, 4.10, 2.42, and 0.35 Ω cm. The current research article covers the preparation of copper chromium delafossite thin films. These thin films can be suitable for hole transport layers in transparent optoelectronic devices. Full article
(This article belongs to the Special Issue Nanostructural Thin Films: Microstructure and Optical Properties)
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15 pages, 2739 KiB  
Article
Enhancing the Performance of Quantum Dot Light-Emitting Diodes Using Solution-Processable Highly Conductive Spinel Structure CuCo2O4 Hole Injection Layer
by Min Ho Park, Min Gye Kim, Jin Hyun Ma, Jun Hyung Jeong, Hyoun Ji Ha, Wonsik Kim, Soohyung Park and Seong Jun Kang
Materials 2023, 16(3), 972; https://doi.org/10.3390/ma16030972 - 20 Jan 2023
Cited by 1 | Viewed by 2455
Abstract
Charge imbalance in quantum-dot light-emitting diodes (QLEDs) causes emission degradation. Therefore, many studies focused on improving hole injection into the QLEDs-emitting layer owing to lower hole conductivity compared to electron conductivity. Herein, CuCo2O4 has a relatively higher hole conductivity than [...] Read more.
Charge imbalance in quantum-dot light-emitting diodes (QLEDs) causes emission degradation. Therefore, many studies focused on improving hole injection into the QLEDs-emitting layer owing to lower hole conductivity compared to electron conductivity. Herein, CuCo2O4 has a relatively higher hole conductivity than other binary oxides and can induce an improved charge balance. As the annealing temperature decreases, the valence band maximum (VBM) of CuCo2O4 shifts away from the Fermi energy level (EF), resulting in an enhanced hole injection through better energy level alignment with hole transport layer. The maximum luminance and current efficiency of the CuCo2O4 hole injection layer (HIL) of the QLED were measured as 93,607 cd/m2 and 11.14 cd/A, respectively, resulting in a 656% improvement in luminous performance of QLEDs compared to conventional metal oxide HIL-based QLEDs. These results demonstrate that the electrical properties of CuCo2O4 can be improved by adjusting the annealing temperature, suggesting that solution-processed spinel can be applied in various optoelectronic devices. Full article
(This article belongs to the Special Issue Quantum Dots for Optoelectronic Devices)
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