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Materials, Volume 7, Issue 2 (February 2014), Pages 623-1443

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Editorial

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Open AccessEditorial Materials Best Paper Award 2014
Materials 2014, 7(2), 1441-1443; doi:10.3390/ma7021441
Received: 14 February 2014 / Revised: 14 February 2014 / Accepted: 15 February 2014 / Published: 24 February 2014
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Abstract Materials instituted an annual award in order to acknowledge outstanding papers in the area of materials science and engineering published in Materials. [...] Full article
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Research

Jump to: Editorial, Review

Open AccessArticle In vitro Endothelialization and Platelet Adhesion on Titaniferous Upgraded Polyether and Polycarbonate Polyurethanes
Materials 2014, 7(2), 623-636; doi:10.3390/ma7020623
Received: 16 August 2013 / Revised: 16 January 2014 / Accepted: 19 January 2014 / Published: 24 January 2014
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Abstract
Polycarbonateurethanes (PCU) and polyetherurethanes (PEU) are used for medical devices, however their bio- and haemocompatibility is limited. In this study, the effect of titaniferous upgrading of different polyurethanes on the bio- and haemocompatibility was investigated by endothelial cell (EC) adhesion/proliferation and platelet [...] Read more.
Polycarbonateurethanes (PCU) and polyetherurethanes (PEU) are used for medical devices, however their bio- and haemocompatibility is limited. In this study, the effect of titaniferous upgrading of different polyurethanes on the bio- and haemocompatibility was investigated by endothelial cell (EC) adhesion/proliferation and platelet adhesion (scanning electron microscopy), respectively. There was no EC adhesion/proliferation and only minor platelet adhesion on upgraded and pure PCU (Desmopan). PEUs (Texin 985, Tecothane 1085, Elastollan 1180A) differed in their cyto- and haemocompatibility. While EC adhesion depended on the type of PEU, any proliferative activity was inhibited. Additional titaniferous upgrading of PEU induced EC proliferation and increased metabolic activity. However, adherent ECs were significantly activated. While Texin was highly thrombotic, only small amounts of platelets adhered onto Tecothane and Elastollan. Additional titaniferous upgrading reduced thrombogenicity of Texin, preserved haemocompatibility of Elastollan, and increased platelet activation/aggregation on Tecothane. In conclusion, none of the PUs was cytocompatible; only titaniferous upgrading allowed EC proliferation and metabolism on PEUs. Haemocompatibility depended on the type of PU. Full article
(This article belongs to the Special Issue Titanium Materials for Biomedical Application 2013)
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Open AccessArticle Comparative Performance of Three Magnesium Compounds on Thermal Degradation Behavior of Red Gum Wood
Materials 2014, 7(2), 637-652; doi:10.3390/ma7020637
Received: 31 October 2013 / Revised: 27 November 2013 / Accepted: 16 January 2014 / Published: 24 January 2014
Cited by 1 | PDF Full-text (885 KB) | HTML Full-text | XML Full-text
Abstract
The effect of basic magnesium carbonate (BMC), magnesium hydroxide (MH), and magnesium chloride hydrate (MCH) on thermal degradation of red gum wood was studied using cone calorimetry, Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis, and X-ray diffraction (XRD) characterization. The results showed common fire [...] Read more.
The effect of basic magnesium carbonate (BMC), magnesium hydroxide (MH), and magnesium chloride hydrate (MCH) on thermal degradation of red gum wood was studied using cone calorimetry, Thermogravimetric-differential scanning calorimetry (TG-DSC) analysis, and X-ray diffraction (XRD) characterization. The results showed common fire retardation actions of the three compounds by releasing incombustible gas and/or water vapor to dilute combustible gas in the flaming zone, and by converting to MgO, which had a satisfactory protective wall effect on the wood. Individually, BMC absorbed heat from the wood at the pre-decomposition stage and, thus, slowed down wood pyrolysis process. It slightly increased the char yield by charring in both the charring stage and the char calcination stage. MH lost water at about 270 °C, close to the temperature at which wood thermally degraded. MH rendered wood char quickly, and the compact char layer impeded further carbonization and burning of inner wood. MCH promoted charring with Mg2+ as a Lewis acid, and increased wood char yield. MCH also released Cl· free radical and HCl at 167 °C, which easily coordinated with combustion reaction radical, and slowed down, even inhibited, the combustion chain reaction. Full article
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Open AccessArticle Preparation of Multifunctional Fe@Au Core-Shell Nanoparticles with Surface Grafting as a Potential Treatment for Magnetic Hyperthermia
Materials 2014, 7(2), 653-661; doi:10.3390/ma7020653
Received: 18 November 2013 / Revised: 26 November 2013 / Accepted: 16 January 2014 / Published: 24 January 2014
Cited by 4 | PDF Full-text (588 KB) | HTML Full-text | XML Full-text
Abstract
Iron core gold shell nanoparticles grafted with Methotrexate (MTX) and indocyanine green (ICG) were synthesized for the first time in this study, and preliminarily evaluated for their potential in magnetic hyperthermia treatment. The core-shell Fe@Au nanoparticles were prepared via the microemulsion process [...] Read more.
Iron core gold shell nanoparticles grafted with Methotrexate (MTX) and indocyanine green (ICG) were synthesized for the first time in this study, and preliminarily evaluated for their potential in magnetic hyperthermia treatment. The core-shell Fe@Au nanoparticles were prepared via the microemulsion process and then grafted with MTX and ICG using hydrolyzed poly(styrene-alt-maleic acid) (PSMA) to obtain core-shell Fe@Au-PSMA-ICG/MTX nanoparticles. MTX is an anti-cancer therapeutic, and ICG is a fluorescent dye. XRD, TEM, FTIR and UV-Vis spectrometry were performed to characterize the nanoparticles. The data indicated that the average size of the nanoparticles was 6.4 ± 09 nm and that the Au coating protected the Fe core from oxidation. MTX and ICG were successfully grafted onto the surface of the nanoparticles. Under exposure to high frequency induction waves, the superparamagnetic nanoparticles elevated the temperature of a solution in a few minutes, which suggested the potential for an application in magnetic hyperthermia treatment. The in vitro studies verified that the nanoparticles were biocompatible; nonetheless, the Fe@Au-PSMA-ICG/MTX nanoparticles killed cancer cells (Hep-G2) via the magnetic hyperthermia mechanism and the release of MTX. Full article
(This article belongs to the Section Biomaterials)
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Open AccessArticle Novel Corrosion Inhibitor for Mild Steel in HCl
Materials 2014, 7(2), 662-672; doi:10.3390/ma7020662
Received: 1 November 2013 / Revised: 28 November 2013 / Accepted: 17 December 2013 / Published: 27 January 2014
Cited by 14 | PDF Full-text (539 KB) | HTML Full-text | XML Full-text
Abstract
Corrosion inhibitory effects of new synthesized compound namely 5,5'- ((1Z,1'Z)-(1,4-phenylenebis(methanylylidene))bis(azanylylidene))bis(1,3,4-thiadiazole-2-thiol) (PBB) on mild steel in 1.0 M HCl was investigated at different temperatures using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results showed that PBB inhibited mild [...] Read more.
Corrosion inhibitory effects of new synthesized compound namely 5,5'- ((1Z,1'Z)-(1,4-phenylenebis(methanylylidene))bis(azanylylidene))bis(1,3,4-thiadiazole-2-thiol) (PBB) on mild steel in 1.0 M HCl was investigated at different temperatures using open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Results showed that PBB inhibited mild steel corrosion in acid solution and indicated that the inhibition efficiencies increased with the concentration of inhibitor, but decreased proportionally with temperature. Changes in impedance parameters suggested the adsorption of PBB on the mild steel surface, leading to the formation of protective films. Full article
Open AccessArticle Effective Optical Properties of Plasmonic Nanocomposites
Materials 2014, 7(2), 727-741; doi:10.3390/ma7020727
Received: 28 November 2013 / Revised: 13 January 2014 / Accepted: 21 January 2014 / Published: 27 January 2014
Cited by 11 | PDF Full-text (1549 KB) | HTML Full-text | XML Full-text
Abstract
Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. [...] Read more.
Plasmonic nanocomposites find many applications, such as nanometric coatings in emerging fields, such as optotronics, photovoltaics or integrated optics. To make use of their ability to affect light propagation in an unprecedented manner, plasmonic nanocomposites should consist of densely packed metallic nanoparticles. This causes a major challenge for their theoretical description, since the reliable assignment of effective optical properties with established effective medium theories is no longer possible. Established theories, e.g., the Maxwell-Garnett formalism, are only applicable for strongly diluted nanocomposites. This effective description, however, is a prerequisite to consider plasmonic nanocomposites in the design of optical devices. Here, we mitigate this problem and use full wave optical simulations to assign effective properties to plasmonic nanocomposites with filling fractions close to the percolation threshold. We show that these effective properties can be used to properly predict the optical action of functional devices that contain nanocomposites in their design. With this contribution we pave the way to consider plasmonic nanocomposites comparably to ordinary materials in the design of optical elements. Full article
(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles 2013)
Open AccessArticle Synthesis of Silver Particle onto Bamboo Charcoal by Tripropylene Glycol and the Composites Characterization
Materials 2014, 7(2), 742-750; doi:10.3390/ma7020742
Received: 20 December 2013 / Revised: 6 January 2014 / Accepted: 20 January 2014 / Published: 27 January 2014
Cited by 1 | PDF Full-text (515 KB) | HTML Full-text | XML Full-text
Abstract
In this study, tripropylene glycol was used as a reducting agent in the polyol process to reduce silver nitrate to the form of silver particles deposited onto the surface of bamboo charcoal (BC). The reduction temperature and time were critical parameters as [...] Read more.
In this study, tripropylene glycol was used as a reducting agent in the polyol process to reduce silver nitrate to the form of silver particles deposited onto the surface of bamboo charcoal (BC). The reduction temperature and time were critical parameters as they control the size of the silver particles formed as well as their distribution onto the surface of the BC. The reduction of silver nitrate by the tripropylene glycol occurred at a temperature of 120 °C for 3 h, and the silver particles, which had a face-centered cubic lattice structure, were distributed onto the surface of the BC. These synthesis conditions should work well with tripropylene glycol as reducing agent that can be helpful in the convenient preparation of Ag/BC particles. When Ag/BC powders were manufactured using 3 g of silver nitrate content, the prepared composites had the largest thermal conductivity at 0.2490 W/(m·K). Full article
Open AccessArticle Shape Memory Properties of PBS-Silica Hybrids
Materials 2014, 7(2), 751-768; doi:10.3390/ma7020751
Received: 23 December 2013 / Revised: 21 January 2014 / Accepted: 22 January 2014 / Published: 27 January 2014
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Abstract
A series of novel Si–O–Si crosslinked organic/inorganic hybrid semi-crystalline polymers with shape memory properties was prepared from alkoxysilane-terminated poly(butylene succinate) (PBS) by water-induced silane crosslinking under organic solvent-free and catalyst-free conditions. The hydrolyzation and condensation of alkoxysilane end groups allowed for the [...] Read more.
A series of novel Si–O–Si crosslinked organic/inorganic hybrid semi-crystalline polymers with shape memory properties was prepared from alkoxysilane-terminated poly(butylene succinate) (PBS) by water-induced silane crosslinking under organic solvent-free and catalyst-free conditions. The hydrolyzation and condensation of alkoxysilane end groups allowed for the generation of silica-like crosslinking points between the polymeric chains, acting not only as chemical net-points, but also as inorganic filler for a reinforcement effect. The resulting networks were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic-mechanical analysis (DMA) and tensile and shape memory tests to gain insight into the relationship between the polymeric structure, the morphology and the properties. By controlling the molecular weight of the PBS precursor, a fine tuning of the crosslinking density and the inorganic content of the resulting network was possible, leading to different thermal, mechanical and shape memory properties. Thanks to their suitable morphology consisting of crystalline domains, which represent the molecular switches between the temporary and permanent shapes, and chemical net-points, which permit the shape recovery, the synthesized materials showed good shape memory characteristics, being able to fix a significant portion of the applied strain in a temporary shape and to restore their original shape above their melting temperature. Full article
(This article belongs to the Special Issue Advances in Functional Hybrid Materials)
Open AccessArticle Inhibition of Mild Steel Corrosion in Sulfuric Acid Solution by New Schiff Base
Materials 2014, 7(2), 787-804; doi:10.3390/ma7020787
Received: 21 October 2013 / Revised: 22 November 2013 / Accepted: 2 January 2014 / Published: 28 January 2014
Cited by 6 | PDF Full-text (1607 KB) | HTML Full-text | XML Full-text
Abstract
The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene) hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD) and electrochemical frequently modulation (EFM) in addition to the adsorption [...] Read more.
The efficiency of Schiff base derived from 4-aminoantipyrine, namely 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene) hydrazinecarbothioamide as a corrosion inhibitor on mild steel in 1.0 M H2SO4 was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD) and electrochemical frequently modulation (EFM) in addition to the adsorption isotherm, corrosion kinetic parameters and scanning electron microscopy (SEM). The results showed that this inhibitor behaved as a good corrosion inhibitor, even at low concentration, with a mean efficiency of 93% and, also, a reduction of the inhibition efficiency as the solution temperature increases. A polarization technique and EIS were tested for different concentrations and different temperatures to reveal that this compound is adsorbed on the mild steel, therefore blocking the active sites, and the adsorption follows the Langmuir adsorption isotherm model. The excellent inhibition effectiveness of 2-(1,5-dimethyl-4-(2-methylbenzylidene)amino)-2-phenyl-1H-pyrazol-3(2H)-ylidene)hydrazinecarbothioamide was also verified by scanning electron microscope (SEM). Full article
Open AccessArticle Study on Surface Permeability of Concrete under Immersion
Materials 2014, 7(2), 876-886; doi:10.3390/ma7020876
Received: 12 December 2013 / Revised: 16 January 2014 / Accepted: 23 January 2014 / Published: 28 January 2014
Cited by 4 | PDF Full-text (579 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher [...] Read more.
In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due to hydration. The two effects work simultaneously and compete throughout the immersion period. The proposed mechanisms get support from microscopic measurements and observations. Full article
(This article belongs to the Section Porous Materials)
Open AccessArticle Corrosion Resistance of Calcium Aluminate Cement Concrete Exposed to a Chloride Environment
Materials 2014, 7(2), 887-898; doi:10.3390/ma7020887
Received: 21 October 2013 / Revised: 20 January 2014 / Accepted: 24 January 2014 / Published: 28 January 2014
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Abstract
The present study concerns a development of calcium aluminate cement (CAC) concrete to enhance the durability against an externally chemically aggressive environment, in particular, chloride-induced corrosion. To evaluate the inhibition effect and concrete properties, CAC was partially mixed with ordinary Portland cement [...] Read more.
The present study concerns a development of calcium aluminate cement (CAC) concrete to enhance the durability against an externally chemically aggressive environment, in particular, chloride-induced corrosion. To evaluate the inhibition effect and concrete properties, CAC was partially mixed with ordinary Portland cement (OPC), ranging from 5% to 15%, as a binder. As a result, it was found that an increase in the CAC in binder resulted in a dramatic decrease in the setting time of fresh concrete. However, the compressive strength was lower, ranging about 20 MPa, while OPC indicated about 30–35 MPa at an equivalent age. When it comes to chloride transport, there was only marginal variation in the diffusivity of chloride ions. The corrosion resistance of CAC mixture was significantly enhanced: its chloride threshold level for corrosion initiation exceeded 3.0% by weight of binder, whilst OPC and CAC concrete indicated about 0.5%–1.0%. Full article
(This article belongs to the Special Issue Construction Materials)
Open AccessCommunication Long-Term Stability of a Cellulose-Based Glucose Oxidase Membrane
Materials 2014, 7(2), 899-905; doi:10.3390/ma7020899
Received: 28 November 2013 / Revised: 22 January 2014 / Accepted: 23 January 2014 / Published: 28 January 2014
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Abstract
A cellulose-based glucose oxidase membrane was prepared on a glassy carbon (GC) electrode. The current response of the electrode to glucose was measured by applying a potential of 1.0 V vs. Ag/AgCl on the base GC and was proportional to the concentration [...] Read more.
A cellulose-based glucose oxidase membrane was prepared on a glassy carbon (GC) electrode. The current response of the electrode to glucose was measured by applying a potential of 1.0 V vs. Ag/AgCl on the base GC and was proportional to the concentration of glucose up to 1 mM. The long-term stability of the electrode was examined by measuring the daily glucose response. Over four months, the response magnitude was maintained and then gradually decreased. After 11 months, though the response magnitude decreased to 50% of the initial value, the linear response range did not change. Therefore, the electrode could be used as a glucose biosensor even after 11 months of use. The entrapment of the enzyme in the cellulose matrix promoted the stability of the enzyme, as revealed by data on the enzyme activity after the enzyme electrode was immersed in urea. Therefore, the cellulose matrix may be used to improve the performance of biosensors, bioreactors and bio-fuel cells. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessArticle Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells
Materials 2014, 7(2), 948-962; doi:10.3390/ma7020948
Received: 30 September 2013 / Revised: 2 January 2014 / Accepted: 20 January 2014 / Published: 7 February 2014
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Abstract
In this study, silicon nitride (SiNx) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiNx [...] Read more.
In this study, silicon nitride (SiNx) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiNx/PI substrates at room temperature (RT), 100 and 200 °C by radio frequency (RF) magnetron sputtering. The thicknesses of the GZO and SiNx thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiNx thin films were a working pressure of 800 × 10−3 Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH4 = 20 sccm and NH3 = 210 sccm, respectively. For the GZO/PI and GZO-SiNx/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiNx/PI substrates with thickness of ~1000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si) thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiNx/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiNx/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiNx/PI. Full article
(This article belongs to the Special Issue Solar Energy Materials 2013)
Open AccessArticle Effects of Particle Size on the Shear Behavior of Coarse Grained Soils Reinforced with Geogrid
Materials 2014, 7(2), 963-979; doi:10.3390/ma7020963
Received: 8 December 2013 / Revised: 2 January 2014 / Accepted: 20 January 2014 / Published: 7 February 2014
Cited by 4 | PDF Full-text (1121 KB) | HTML Full-text | XML Full-text
Abstract
In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests [...] Read more.
In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests on three types of coarse grained soils (4.5 mm, 7.9 mm, and 15.9 mm) were performed to evaluate the effects of particle size on the shear behavior of coarse grained soils with/without geogrid reinforcements. Based on the direct shear test results, it was found that, in the case of no-reinforcement, the larger the maximum particle size became, the larger the friction angle was. Compared with the no-reinforcement case, the cases reinforced with either soft geogrid or stiff geogrid have smaller friction angles. The cohesion of the soil reinforced with stiff geogrid was larger than that of the soil reinforced with soft geogrid. The difference in the shear strength occurs because the case with a stiff geogrid has more soil to geogrid contact area, leading to the reduction in interlocking between soil particles. Full article
Open AccessArticle Vascular Endothelial Growth Factor (VEGF) Detection Using an Aptamer and PNA-Based Bound/Free Separation System
Materials 2014, 7(2), 1046-1054; doi:10.3390/ma7021046
Received: 13 December 2013 / Revised: 15 January 2014 / Accepted: 28 January 2014 / Published: 11 February 2014
Cited by 4 | PDF Full-text (330 KB) | HTML Full-text | XML Full-text
Abstract
We have developed a bound/free separation system using a vascular endothelial growth factor (VEGF) aptamer and a peptide nucleic acid (PNA) to detect VEGF. In this system, we designed capture PNA (CaPNA), which hybridizes with the aptamer in the absence of the [...] Read more.
We have developed a bound/free separation system using a vascular endothelial growth factor (VEGF) aptamer and a peptide nucleic acid (PNA) to detect VEGF. In this system, we designed capture PNA (CaPNA), which hybridizes with the aptamer in the absence of the target protein, but does not hybridize with the aptamer in the presence of the target protein due to steric hindrance and/or stabilization of the aptamer’s structure. By removing the aptamers not bound to the target protein using CaPNA immobilized beads, we can detect the target protein by measuring signals labeled with the aptamer in the supernatant. In this study, we detected VEGF using CaPNA-immobilized beads without the time-consuming washing step. This simple and rapid system can detect 25 nM of VEGF in 15 min. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessArticle Detection of Waterborne and Airborne Formaldehyde: From Amperometric Chemosensing to a Visual Biosensor Based on Alcohol Oxidase
Materials 2014, 7(2), 1055-1068; doi:10.3390/ma7021055
Received: 29 November 2013 / Revised: 17 December 2013 / Accepted: 8 January 2014 / Published: 11 February 2014
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Abstract
A laboratory prototype of a microcomputer-based analyzer was developed for quantitative determination of formaldehyde in liquid samples, based on catalytic chemosensing elements. It was shown that selectivity for the target analyte could be increased by modulating the working electrode potential. Analytical parameters [...] Read more.
A laboratory prototype of a microcomputer-based analyzer was developed for quantitative determination of formaldehyde in liquid samples, based on catalytic chemosensing elements. It was shown that selectivity for the target analyte could be increased by modulating the working electrode potential. Analytical parameters of three variants of the amperometric analyzer that differed in the chemical structure/configuration of the working electrode were studied. The constructed analyzer was tested on wastewater solutions that contained formaldehyde. A simple low-cost biosensor was developed for semi-quantitative detection of airborne formaldehyde in concentrations exceeding the threshold level. This biosensor is based on a change in the color of a solution that contains a mixture of alcohol oxidase from the yeast Hansenula polymorpha, horseradish peroxidase and a chromogen, following exposure to airborne formaldehyde. The solution is enclosed within a membrane device, which is permeable to formaldehyde vapors. The most efficient and sensitive biosensor for detecting formaldehyde was the one that contained alcohol oxidase with an activity of 1.2 U·mL−1. The biosensor requires no special instrumentation and enables rapid visual detection of airborne formaldehyde at concentrations, which are hazardous to human health. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessArticle Direct Electrochemistry and Electrocatalysis of Horseradish Peroxidase Immobilized in a DNA/Chitosan-Fe3O4 Magnetic Nanoparticle Bio-Complex Film
Materials 2014, 7(2), 1069-1083; doi:10.3390/ma7021069
Received: 30 November 2013 / Revised: 25 December 2013 / Accepted: 27 January 2014 / Published: 11 February 2014
Cited by 4 | PDF Full-text (1071 KB) | HTML Full-text | XML Full-text
Abstract
A DNA/chitosan-Fe3O4 magnetic nanoparticle bio-complex film was constructed for the immobilization of horseradish peroxidase (HRP) on a glassy carbon electrode. HRP was simply mixed with DNA, chitosan and Fe3O4 nanoparticles, and then applied to the electrode [...] Read more.
A DNA/chitosan-Fe3O4 magnetic nanoparticle bio-complex film was constructed for the immobilization of horseradish peroxidase (HRP) on a glassy carbon electrode. HRP was simply mixed with DNA, chitosan and Fe3O4 nanoparticles, and then applied to the electrode surface to form an enzyme-incorporated polyion complex film. Scanning electron microscopy (SEM) was used to study the surface features of DNA/chitosan/Fe3O4/HRP layer. The results of electrochemical impedance spectroscopy (EIS) show that Fe3O4 and enzyme were successfully immobilized on the electrode surface by the DNA/chitosan bio-polyion complex membrane. Direct electron transfer (DET) and bioelectrocatalysis of HRP in the DNA/chitosan/Fe3O4 film were investigated by cyclic voltammetry (CV) and constant potential amperometry. The HRP-immobilized electrode was found to undergo DET and exhibited a fast electron transfer rate constant of 3.7 s−1. The CV results showed that the modified electrode gave rise to well-defined peaks in phosphate buffer, corresponding to the electrochemical redox reaction between HRP(Fe(III)) and HRP(Fe(II)). The obtained electrode also displayed an electrocatalytic reduction behavior towards H2O2. The resulting DNA/chitosan/Fe3O4/HRP/glassy carbon electrode (GCE) shows a high sensitivity (20.8 A·cm−2·M−1) toward H2O2. A linear response to H2O2 measurement was obtained over the range from 2 µM to 100 µM (R2 = 0.99) and an amperometric detection limit of 1 µM (S/N = 3). The apparent Michaelis-Menten constant of HRP immobilized on the electrode was 0.28 mM. Furthermore, the electrode exhibits both good operational stability and storage stability. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessArticle Silicate Removal in Aluminum Hydroxide Co-Precipitation Process
Materials 2014, 7(2), 1084-1096; doi:10.3390/ma7021084
Received: 3 December 2013 / Revised: 2 January 2014 / Accepted: 5 February 2014 / Published: 11 February 2014
Cited by 4 | PDF Full-text (1157 KB) | HTML Full-text | XML Full-text
Abstract
The removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that silicate [...] Read more.
The removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that silicate uptake occurred by adsorption to boehmite for initial Si/Al molar ratios smaller than two, but by precipitation of poorly crystalline kaolinite for the ratios larger than two, in both co-precipitation and adsorption processes. Silicate was removed by two steps: (i) an initial rapid uptake in a few seconds; and (ii) a slow uptake over several hours in both processes. The uptake rate in the first step was higher in the co-precipitation process than in adsorption process, presumably due to increased silicate adsorption to boehmite and rapid precipitation of kaolinite. These results suggest that silicate removal using aluminum salts could be effectively achieved if the pH adjustment and aluminum concentration are strictly controlled. Full article
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Open AccessArticle The Effect of Exogenous Zinc Concentration on the Responsiveness of MC3T3-E1 Pre-Osteoblasts to Surface Microtopography: Part II (Differentiation)
Materials 2014, 7(2), 1097-1112; doi:10.3390/ma7021097
Received: 20 December 2013 / Revised: 24 January 2014 / Accepted: 28 January 2014 / Published: 11 February 2014
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Abstract
Osseointegration of bone implants is a vital part of the recovery process. Numerous studies have shown that micropatterned geometries can promote cell-substrate associations and strengthen the bond between tissue and the implanted material. As demonstrated previously, exogenous zinc levels can influence the [...] Read more.
Osseointegration of bone implants is a vital part of the recovery process. Numerous studies have shown that micropatterned geometries can promote cell-substrate associations and strengthen the bond between tissue and the implanted material. As demonstrated previously, exogenous zinc levels can influence the responsiveness of pre-osteoblasts to micropatterns and modify their migratory behavior. In this study, we sought to determine the effect of exogenous zinc on differentiation of osteoblasts cultured on micropatterned vs. planar substrates. Levels of activated metalloproteinase-2 (MMP-2) and transforming growth factor-beta 1 (TGF-β1), as well as early stage differentiation marker alkaline phosphatase, were altered with the addition of zinc. These results suggest that exogenous zinc concentration and micropatterning may interdependently modulate osteoblast differentiation. Full article
(This article belongs to the Special Issue Biocompatibility of Materials 2013)
Open AccessArticle Dielectric Properties of Dual-Frequency Reactive Mesogens before and after Photopolymerization
Materials 2014, 7(2), 1113-1121; doi:10.3390/ma7021113
Received: 30 December 2013 / Revised: 27 January 2014 / Accepted: 7 February 2014 / Published: 11 February 2014
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Abstract
The dielectric properties of reactive mesogens before and after photopolymerization were investigated. Commercially available nematic reactive mesogens (RMS03-013C, Merck) were measured and found to be dual-frequency liquid crystals. The property arose from the δ-relaxation process that was caused by rotational fluctuations parallel [...] Read more.
The dielectric properties of reactive mesogens before and after photopolymerization were investigated. Commercially available nematic reactive mesogens (RMS03-013C, Merck) were measured and found to be dual-frequency liquid crystals. The property arose from the δ-relaxation process that was caused by rotational fluctuations parallel to the molecule’s long axis. After polymerization, the polymerized reactive mesogens still exhibited this dual-frequency property. The result was attributed to the β-relaxation process which arose from rotational fluctuations of localized parts of the main chain. The sign change of the dielectric anisotropy with increasing frequency after polymerization was opposite to the sign change before polymerization. Full article
Open AccessArticle Investigation on the Cyclic Response of Superelastic Shape Memory Alloy (SMA) Slit Damper Devices Simulated by Quasi-Static Finite Element (FE) Analyses
Materials 2014, 7(2), 1122-1141; doi:10.3390/ma7021122
Received: 5 January 2014 / Revised: 23 January 2014 / Accepted: 24 January 2014 / Published: 11 February 2014
Cited by 3 | PDF Full-text (1776 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the superelastic shape memory alloy (SMA) slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE) analyses. Although the steel slit dampers [...] Read more.
In this paper, the superelastic shape memory alloy (SMA) slit damper system as an alternative design approach for steel structures is intended to be evaluated with respect to inelastic behavior simulated by refined finite element (FE) analyses. Although the steel slit dampers conventionally used for aseismic design are able to dissipate a considerable amount of energy generated by the plastic yielding of the base materials, large permanent deformation may occur in the entire structure. After strong seismic events, extra damage repair costs are required to restore the original configuration and to replace defective devices with new ones. Innovative slit dampers fabricated by superelastic SMAs that automatically recover their initial conditions only by the removal of stresses without heat treatment are introduced with a view toward mitigating the problem of permanent deformation. The cyclically tested FE models are calibrated to experimental results for the purpose of predicting accurate behavior. This study also focuses on the material constitutive model that is able to reproduce the inherent behavior of superelastic SMA materials by taking phase transformation between austenite and martensite into consideration. The responses of SMA slit dampers are compared to those of steel slit dampers. Axial stress and strain components are also investigated on the FE models under cyclic loading in an effort to validate the adequacy of FE modeling and then to compare between two slit damper systems. It can be shown that SMA slit dampers exhibit many structural advantages in terms of ultimate strength, moderate energy dissipation and recentering capability. Full article
(This article belongs to the Special Issue Shape Memory Materials)
Open AccessArticle Carbon Felt-Based Bioelectrocatalytic Flow-Through Detectors: 2,6-Dichlorophenol Indophenol and Peroxidase Coadsorbed Carbon-Felt for Flow-Amperometric Determination of Hydrogen Peroxide
Materials 2014, 7(2), 1142-1154; doi:10.3390/ma7021142
Received: 30 November 2013 / Revised: 8 January 2014 / Accepted: 7 February 2014 / Published: 12 February 2014
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Abstract
2,6-dichlorophenol indophenol (DCIP) and horseradish peroxidase (HRP) were coadsorbed on a porous carbon felt (CF) from their mixed aqueous solution under ultrasound irradiation for 5 min. The resulting DCIP and HRP-coadsorbed CF (DCIP/HRP-CF) showed an excellent bioelectrocatalytic activity for the reduction of [...] Read more.
2,6-dichlorophenol indophenol (DCIP) and horseradish peroxidase (HRP) were coadsorbed on a porous carbon felt (CF) from their mixed aqueous solution under ultrasound irradiation for 5 min. The resulting DCIP and HRP-coadsorbed CF (DCIP/HRP-CF) showed an excellent bioelectrocatalytic activity for the reduction of H2O2. The coadsorption of DCIP together with HRP was essential to obtain larger bioelectrocatalytic current to H2O2. The DCIP/HRP-CF was successfully used as a working electrode unit of a bioelectrocatalytic flow-through detector for highly sensitive and continuous amperometric determination of H2O2. Under the optimized operational conditions (i.e., applied potential, +0.2 V versus Ag/AgCl; carrier pH 5.0, and carrier flow rate, 1.9 mL/min), the cathodic peak current of H2O2 linearly increased over the concentration range from 0.1 to 30 µM (the sensitivity, 0.88 µA/µM (slope of linear part); the limit of detection, 0.1 µM (S/N = 3) current noise level, 30 nA) with a sample through-put of ca. 40–90 samples/h. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessArticle Synthesis and Characterization of Holmium-Doped Iron Oxide Nanoparticles
Materials 2014, 7(2), 1155-1164; doi:10.3390/ma7021155
Received: 21 November 2013 / Revised: 28 January 2014 / Accepted: 31 January 2014 / Published: 12 February 2014
Cited by 7 | PDF Full-text (320 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Rare earth atoms exhibit several interesting properties, for example, large magnetic moments and luminescence. Introducing these atoms into a different matrix can lead to a material that shows multiple interesting effects. Holmium atoms were incorporated into an iron oxide nanoparticle and the [...] Read more.
Rare earth atoms exhibit several interesting properties, for example, large magnetic moments and luminescence. Introducing these atoms into a different matrix can lead to a material that shows multiple interesting effects. Holmium atoms were incorporated into an iron oxide nanoparticle and the concentration of the dopant atom was changed in order to determine its influence on the host crystal. Its magnetic and magneto-optical properties were investigated by vibrating sample magnetometry and Faraday rotation measurements. The luminescent characteristics of the material, in solution and incorporated in a polymer thin film, were probed by fluorescence experiments. Full article
(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles 2013)
Open AccessArticle In situ Neutron Diffraction during Casting: Determination of Rigidity Point in Grain Refined Al-Cu Alloys
Materials 2014, 7(2), 1165-1172; doi:10.3390/ma7021165
Received: 19 December 2013 / Revised: 29 January 2014 / Accepted: 6 February 2014 / Published: 12 February 2014
Cited by 3 | PDF Full-text (616 KB) | HTML Full-text | XML Full-text
Abstract
The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses [...] Read more.
The rigidity temperature of a solidifying alloy is the temperature at which the solid plus liquid phases are sufficiently coalesced to transmit long range tensile strains and stresses. It determines the point at which thermally induced deformations start to generate internal stresses in a casting. As such, it is a key parameter in numerical modelling of solidification processes and in studying casting defects such as solidification cracking. This temperature has been determined in Al-Cu alloys using in situ neutron diffraction during casting in a dog bone shaped mould. In such a setup, the thermal contraction of the solidifying material is constrained and stresses develop at a hot spot that is irradiated by neutrons. Diffraction peaks are recorded every 11 s using a large detector, and their evolution allows for the determination of the rigidity temperatures. We measured rigidity temperatures equal to 557 °C and 548 °C, depending on cooling rate, for a grain refined Al-13 wt% Cu alloy. At high cooling rate, rigidity is reached during the formation of the eutectic phase and the solid phase is not sufficiently coalesced, i.e., strong enough, to avoid hot tear formation. Full article
(This article belongs to the Special Issue Light Alloys and Their Applications)
Open AccessArticle Study on Mg/Al Weld Seam Based on Zn–Mg–Al Ternary Alloy
Materials 2014, 7(2), 1173-1187; doi:10.3390/ma7021173
Received: 26 December 2013 / Revised: 29 January 2014 / Accepted: 6 February 2014 / Published: 13 February 2014
Cited by 7 | PDF Full-text (1078 KB) | HTML Full-text | XML Full-text
Abstract
Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA) welding. An infrared thermography system was used to measure the temperature of [...] Read more.
Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA) welding. An infrared thermography system was used to measure the temperature of the welding pool during the welding process to investigate the solidification process. It was found that the mechanical properties of the welded joints were improved with the increasing of the Al content in the Zn–xAl filler metals, and when Zn–30Al was used as the filler metal, the ultimate tensile strength could reach a maximum of 120 MPa. The reason for the average tensile strength of the joint increasing was that the weak zone of the joint using Zn–30Al filler metal was generated primarily by α-Al instead of MgZn2. When Zn–40Al was used as the filler metal, a new transition zone, about 20 μm-wide, appeared in the edge of the fusion zone near the Mg base metal. Due to the transition zones consisting of MgZn2- and Al-based solid solution, the mechanical property of the joints was deteriorated. Full article
(This article belongs to the Special Issue Light Alloys and Their Applications)
Open AccessArticle Effect of Al–5Ti–C Master Alloy on the Microstructure and Mechanical Properties of Hypereutectic Al–20%Si Alloy
Materials 2014, 7(2), 1188-1200; doi:10.3390/ma7021188
Received: 11 June 2013 / Revised: 8 February 2014 / Accepted: 10 February 2014 / Published: 14 February 2014
Cited by 2 | PDF Full-text (3570 KB) | HTML Full-text | XML Full-text
Abstract
Al–5Ti–C master alloy was prepared and used to modify hypereutectic Al–20%Si alloy. The microstructure evolution and mechanical properties of hypereutectic Al–20%Si alloy with Al–5Ti–C master alloy additions (0, 0.4, 0.6, 1.0, 1.6 and 2.0 wt%) were investigated. The results show that, Al–5Ti–C [...] Read more.
Al–5Ti–C master alloy was prepared and used to modify hypereutectic Al–20%Si alloy. The microstructure evolution and mechanical properties of hypereutectic Al–20%Si alloy with Al–5Ti–C master alloy additions (0, 0.4, 0.6, 1.0, 1.6 and 2.0 wt%) were investigated. The results show that, Al–5Ti–C master alloy (0.6 wt%, 10 min) can significantly refine both eutectic and primary Si of hypereutectic Al–20%Si alloy. The morphology of the primary Si crystals was significantly refined from a coarse polygonal and star-like shape to a fine polyhedral shape and the grain size of the primary Si was refined from roughly 90–120 μm to 20–50 μm. The eutectic Si phases were modified from a coarse platelet-like/needle-like structure to a fine fibrous structure with discrete particles. The Al–5Ti–C master alloy (0.6 wt%, 30 min) still has a good refinement effect. The ultimate tensile strength (UTS), elongation (El) and Brinell hardness (HB) of Al–20%Si alloy modified by the Al–5Ti–C master alloy (0.6 wt%, 10 min) increased by roughly 65%, 70% and 51%, respectively, due to decreasing the size and changing the morphology on the primary and eutectic Si crystals. The change in mechanical properties corresponds to evolution of the microstructure. Full article
(This article belongs to the Special Issue Light Alloys and Their Applications)
Open AccessArticle Effect of Sample Elevation in Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RF PECVD) Reactor on Optical Properties and Deposition Rate of Silicon Nitride Thin Films
Materials 2014, 7(2), 1249-1260; doi:10.3390/ma7021249
Received: 11 December 2013 / Revised: 27 January 2014 / Accepted: 12 February 2014 / Published: 17 February 2014
Cited by 2 | PDF Full-text (753 KB) | HTML Full-text | XML Full-text
Abstract
In this paper we investigate influence of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) process parameters, which include gas flows, pressure and temperature, as well as a way of sample placement in the reactor, on optical properties and deposition rate [...] Read more.
In this paper we investigate influence of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) process parameters, which include gas flows, pressure and temperature, as well as a way of sample placement in the reactor, on optical properties and deposition rate of silicon nitride (SiNx) thin films. The influence of the process parameters has been determined using Taguchi’s orthogonal tables approach. As a result of elevating samples above the electrode, it has been found that deposition rate strongly increases with distance between sample and the stage electrode, and reaches its maximum 7 mm above the electrode. Moreover, the refractive index of the films follows increase of the thickness. The effect can be observed when the thickness of the film is below 80 nm. It has been also found that when the deposition temperature is reduced down to 200 °C, as required for many temperature-sensitive substrate materials, the influence of the substrate material (Si or oxidized Si) can be neglected from the point of view of the properties of the films. We believe that the obtained results may help in designing novel complex in shape devices, where optical properties and thickness of thin plasma-deposited coatings need to be well defined. Full article
Open AccessArticle Effect of the Cu Source on Optical Properties of CuZnO Films Deposited by Ultrasonic Spraying
Materials 2014, 7(2), 1261-1270; doi:10.3390/ma7021261
Received: 27 December 2013 / Revised: 17 January 2014 / Accepted: 7 February 2014 / Published: 18 February 2014
Cited by 6 | PDF Full-text (761 KB) | HTML Full-text | XML Full-text
Abstract
CuZnO (CZO) films have received considerable attention, owing to their potential applications in semiconductor devices, including gas sensors or solar cells. However, exactly how these films affect the properties of CZO films by using different Cu sources has seldom been investigated. This [...] Read more.
CuZnO (CZO) films have received considerable attention, owing to their potential applications in semiconductor devices, including gas sensors or solar cells. However, exactly how these films affect the properties of CZO films by using different Cu sources has seldom been investigated. This study demonstrates the feasibility of preparing CZO films by using different Cu sources via a simple ultrasonic spray method, in which copper nitrate and copper acetate were used as copper sources. Optical properties of CZO films prepared by copper nitrate and copper acetate were also investigated, based on transmittance and photoluminescence measurements. Additionally, the composition and the morphology of the films were investigated using the X-ray diffraction analysis and field emission scanning electron microscopy. The results of this study demonstrate that the CZO films prepared by using copper acetate exhibit better optical properties. Full article
(This article belongs to the Special Issue New Energy Materials)
Open AccessArticle Mechanical Behavior of AZ31B Mg Alloy Sheets under Monotonic and Cyclic Loadings at Room and Moderately Elevated Temperatures
Materials 2014, 7(2), 1271-1295; doi:10.3390/ma7021271
Received: 20 December 2013 / Revised: 6 February 2014 / Accepted: 6 February 2014 / Published: 18 February 2014
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Abstract
Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension [...] Read more.
Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension at and slightly above room temperature were recorded. Strong yielding asymmetry and nonlinear hardening behavior were also revealed. Considerable Bauschinger effects, transient behavior, and variable permanent softening responses were observed near room temperature, but these were reduced and almost disappeared as the temperature increased. Different stress–strain responses were inherent to the activation of twinning at lower temperatures and non-basal slip systems at elevated temperatures. A critical temperature was identified to account for the transition between the twinning-dominant and slip-dominant deformation mechanisms. Accordingly, below the transition point, stress–strain curves of cyclic loading tests exhibited concave-up shapes for compression or compression following tension, and an unusual S-shape for tension following compression. This unusual shape disappeared when the temperature was above the transition point. Shrinkage of the elastic range and variation in Young’s modulus due to plastic strain deformation during stress reversals were also observed. The texture-induced anisotropy of both the elastic and plastic behaviors was characterized experimentally. Full article
(This article belongs to the Special Issue Light Alloys and Their Applications)
Open AccessArticle Gelatin-Based Hydrogels Promote Chondrogenic Differentiation of Human Adipose Tissue-Derived Mesenchymal Stem Cells In Vitro
Materials 2014, 7(2), 1342-1359; doi:10.3390/ma7021342
Received: 20 December 2013 / Revised: 24 January 2014 / Accepted: 27 January 2014 / Published: 19 February 2014
Cited by 11 | PDF Full-text (3893 KB) | HTML Full-text | XML Full-text
Abstract
Due to the weak regeneration potential of cartilage, there is a high clinical incidence of articular joint disease, leading to a strong demand for cartilaginous tissue surrogates. The aim of this study was to evaluate a gelatin-based hydrogel for its suitability to [...] Read more.
Due to the weak regeneration potential of cartilage, there is a high clinical incidence of articular joint disease, leading to a strong demand for cartilaginous tissue surrogates. The aim of this study was to evaluate a gelatin-based hydrogel for its suitability to support chondrogenic differentiation of human mesenchymal stem cells. Gelatin-based hydrogels are biodegradable, show high biocompatibility, and offer possibilities to introduce functional groups and/or ligands. In order to prove their chondrogenesis-supporting potential, a hydrogel film was developed and compared with standard cell culture polystyrene regarding the differentiation behavior of human mesenchymal stem cells. Cellular basis for this study were human adipose tissue-derived mesenchymal stem cells, which exhibit differentiation potential along the adipogenic, osteogenic and chondrogenic lineage. The results obtained show a promotive effect of gelatin-based hydrogels on chondrogenic differentiation of mesenchymal stem cells in vitro and therefore encourage subsequent in vivo studies. Full article
(This article belongs to the Special Issue Biocompatibility of Materials 2013)
Open AccessArticle Plant-Mediated Fabrication and Surface Enhanced Raman Property of Flower-Like Au@Pd Nanoparticles
Materials 2014, 7(2), 1360-1369; doi:10.3390/ma7021360
Received: 20 January 2014 / Revised: 11 February 2014 / Accepted: 17 February 2014 / Published: 19 February 2014
Cited by 4 | PDF Full-text (756 KB) | HTML Full-text | XML Full-text
Abstract
The flower-like nanostructures of an Au core and Pd petals with the average size of 47.8 nm were fabricated through the successive reduction of HAuCl4 and Na2PdCl4 at room temperature. During the synthesis, Cacumen Platycladi leaf extract served [...] Read more.
The flower-like nanostructures of an Au core and Pd petals with the average size of 47.8 nm were fabricated through the successive reduction of HAuCl4 and Na2PdCl4 at room temperature. During the synthesis, Cacumen Platycladi leaf extract served as weak reductant and capping agent. Characterization techniques such as Energy-dispersive X-ray spectroscopy, UV-Vis spectroscopy, and X-ray diffraction characterizations were employed to confirm that the as-synthesized nanoparticles have the structure of core-shell. The obtained core-shell nanoflowers exhibited good surface enhanced Raman spectroscopic activity with Rhodamine 6G. Full article
(This article belongs to the Special Issue Advances in Nanoporous Materials)
Figures

Open AccessArticle Preparation and Catalytic Activity of Carbon Nanofibers Anchored Metallophthalocyanine in Decomposing Acid Orange 7
Materials 2014, 7(2), 1370-1383; doi:10.3390/ma7021370
Received: 19 December 2013 / Revised: 9 February 2014 / Accepted: 11 February 2014 / Published: 20 February 2014
Cited by 1 | PDF Full-text (1226 KB) | HTML Full-text | XML Full-text
Abstract
Amine-modified CNFs (AN-CNFs) were first obtained through the Billups reaction from carbon nanofibers (CNFs), and were used as supports of cobalt tetracarboxylphthalocyanine (CoTCPc) for the catalytic oxidation of Acid Orange 7 (AO7) in the CoTCPc-AN-CNFs/H2O2 system. CNFs, AN-CNFs and [...] Read more.
Amine-modified CNFs (AN-CNFs) were first obtained through the Billups reaction from carbon nanofibers (CNFs), and were used as supports of cobalt tetracarboxylphthalocyanine (CoTCPc) for the catalytic oxidation of Acid Orange 7 (AO7) in the CoTCPc-AN-CNFs/H2O2 system. CNFs, AN-CNFs and CoTCPc-AN-CNFs were characterized by X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission electron microscopy and N2 adsorption-desorption. The oxidative decoloration of AO7 in the presence of CoTCPcNa-AN-CNFs and H2O2 was investigated by UV-Vis absorption spectra. The results showed that AO7 was oxidized efficiently in the CoTCPcNa-AN-CNFs /H2O2 system. The benzene ring was first introduced between CNFs and MPcs. However, its catalytic efficiency and electronic properties would not weaken. New catalytic mechanism may display in this CoTCPcNa-AN-CNFs /H2O2 system. Full article
Open AccessArticle Structural Characterization of Polymer-Clay Nanocomposites Prepared by Co-Precipitation Using EPR Techniques
Materials 2014, 7(2), 1384-1408; doi:10.3390/ma7021384
Received: 15 December 2013 / Revised: 16 February 2014 / Accepted: 17 February 2014 / Published: 21 February 2014
Cited by 1 | PDF Full-text (1772 KB) | HTML Full-text | XML Full-text
Abstract
Polymer-clay nanocomposites (PCNCs) containing either a rubber or an acrylate polymer were prepared by drying or co-precipitating polymer latex and nanolayered clay (synthetic and natural) suspensions. The interface between the polymer and the clay nanoparticles was studied by electron paramagnetic resonance (EPR) [...] Read more.
Polymer-clay nanocomposites (PCNCs) containing either a rubber or an acrylate polymer were prepared by drying or co-precipitating polymer latex and nanolayered clay (synthetic and natural) suspensions. The interface between the polymer and the clay nanoparticles was studied by electron paramagnetic resonance (EPR) techniques by selectively addressing spin probes either to the surfactant layer (labeled stearic acid) or the clay surface (labeled catamine). Continuous-wave (CW) EPR studies of the surfactant dynamics allow to define a transition temperature T* which was tentatively assigned to the order-disorder transition of the surfactant layer. CW EPR studies of PCNC showed that completely exfoliated nanoparticles coexist with agglomerates. HYSCORE spectroscopy in PCNCs showed couplings within the probe −assigned with DFT computations− and couplings with nuclei of the environment, 1H and 23Na for the surfactant layer probe, and 29Si, 7Li, 19F and 23Na for the clay surface probe. Analysis of these couplings indicates that the integrity of the surfactant layer is conserved and that there are sizeable ionic regions containing sodium ions directly beyond the surfactant layer. Simulations of the very weak couplings demonstrated that the HYSCORE spectra are sensitive to the composition of the clay and whether or not clay platelets stack. Full article
(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles 2013)
Open AccessArticle The Effects of Annealing Temperatures on Composition and Strain in SixGe1−x Obtained by Melting Growth of Electrodeposited Ge on Si (100)
Materials 2014, 7(2), 1409-1421; doi:10.3390/ma7021409
Received: 8 January 2014 / Revised: 11 February 2014 / Accepted: 13 February 2014 / Published: 24 February 2014
Cited by 4 | PDF Full-text (1740 KB) | HTML Full-text | XML Full-text
Abstract
The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100) substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 [...] Read more.
The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100) substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100 °C for 1 s. All annealed samples show single crystalline structure in (100) orientation. A significant appearance of Si-Ge vibration mode peak at ~400 cm−1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of SixGe1−x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance. Full article
Open AccessArticle Influence of Rapid Freeze-Thaw Cycling on the Mechanical Properties of Sustainable Strain-Hardening Cement Composite (2SHCC)
Materials 2014, 7(2), 1422-1440; doi:10.3390/ma7021422
Received: 27 November 2013 / Revised: 11 February 2014 / Accepted: 14 February 2014 / Published: 24 February 2014
Cited by 3 | PDF Full-text (748 KB) | HTML Full-text | XML Full-text
Abstract
This paper provides experimental results to investigate the mechanical properties of sustainable strain-hardening cement composite (2SHCC) for infrastructures after freeze-thaw actions. To improve the sustainability of SHCC materials in this study, high energy-consumptive components—silica sand, cement, and polyvinyl alcohol (PVA) fibers—in the [...] Read more.
This paper provides experimental results to investigate the mechanical properties of sustainable strain-hardening cement composite (2SHCC) for infrastructures after freeze-thaw actions. To improve the sustainability of SHCC materials in this study, high energy-consumptive components—silica sand, cement, and polyvinyl alcohol (PVA) fibers—in the conventional SHCC materials are partially replaced with recycled materials such as recycled sand, fly ash, and polyethylene terephthalate (PET) fibers, respectively. To investigate the mechanical properties of green SHCC that contains recycled materials, the cement, PVA fiber and silica sand were replaced with 10% fly ash, 25% PET fiber, and 10% recycled aggregate based on preliminary experimental results for the development of 2SHCC material, respectively. The dynamic modulus of elasticity and weight for 2SHCC material were measured at every 30 cycles of freeze-thaw. The effects of freeze-thaw cycles on the mechanical properties of sustainable SHCC are evaluated by conducting compressive tests, four-point flexural tests, direct tensile tests and prism splitting tests after 90, 180, and 300 cycles of rapid freeze-thaw. Freeze-thaw testing was conducted according to ASTM C 666 Procedure A. Test results show that after 300 cycles of freezing and thawing actions, the dynamic modulus of elasticity and mass loss of damaged 2SHCC were similar to those of virgin 2SHCC, while the freeze-thaw cycles influence mechanical properties of the 2SHCC material except for compressive behavior. Full article
(This article belongs to the Special Issue Construction Materials)

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Open AccessReview Organic-Inorganic Hybrid Polymers as Adsorbents for Removal of Heavy Metal Ions from Solutions: A Review
Materials 2014, 7(2), 673-726; doi:10.3390/ma7020673
Received: 25 November 2013 / Revised: 6 January 2014 / Accepted: 10 January 2014 / Published: 27 January 2014
Cited by 29 | PDF Full-text (3949 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Over the past decades, organic-inorganic hybrid polymers have been applied in different fields, including the adsorption of pollutants from wastewater and solid-state separations. In this review, firstly, these compounds are classified. These compounds are prepared by sol-gel method, self-assembly process (mesopores), assembling [...] Read more.
Over the past decades, organic-inorganic hybrid polymers have been applied in different fields, including the adsorption of pollutants from wastewater and solid-state separations. In this review, firstly, these compounds are classified. These compounds are prepared by sol-gel method, self-assembly process (mesopores), assembling of nanobuilding blocks (e.g., layered or core-shell compounds) and as interpenetrating networks and hierarchically structures. Lastly, the adsorption characteristics of heavy metals of these materials, including different kinds of functional groups, selectivity of them for heavy metals, effect of pH and synthesis conditions on adsorption capacity, are studied. Full article
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Open AccessReview Biocompatibility of Coronary Stents
Materials 2014, 7(2), 769-786; doi:10.3390/ma7020769
Received: 24 December 2013 / Revised: 20 January 2014 / Accepted: 20 January 2014 / Published: 28 January 2014
Cited by 4 | PDF Full-text (464 KB) | HTML Full-text | XML Full-text
Abstract
Cardiovascular disease is the dominant cause of mortality in developed countries, with coronary artery disease (CAD) a predominant contributor. The development of stents to treat CAD was a significant innovation, facilitating effective percutaneous coronary revascularization. Coronary stents have evolved from bare metal [...] Read more.
Cardiovascular disease is the dominant cause of mortality in developed countries, with coronary artery disease (CAD) a predominant contributor. The development of stents to treat CAD was a significant innovation, facilitating effective percutaneous coronary revascularization. Coronary stents have evolved from bare metal compositions, to incorporate advances in pharmacological therapy in what are now known as drug eluting stents (DES). Deployment of a stent overcomes some limitations of balloon angioplasty alone, but provides an acute stimulus for thrombus formation and promotes neointimal hyperplasia. First generation DES effectively reduced in-stent restenosis, but profoundly delay healing and are susceptible to late stent thrombosis, leading to significant clinical complications in the long term. This review characterizes the development of coronary stents, detailing the incremental improvements, which aim to attenuate the major clinical complications of thrombosis and restenosis. Despite these enhancements, coronary stents remain fundamentally incompatible with the vasculature, an issue which has largely gone unaddressed. We highlight the latest modifications and research directions that promise to more holistically design coronary implants that are truly biocompatible. Full article
(This article belongs to the Section Biomaterials)
Open AccessReview Fabrications and Applications of Stimulus-Responsive Polymer Films and Patterns on Surfaces: A Review
Materials 2014, 7(2), 805-875; doi:10.3390/ma7020805
Received: 26 November 2013 / Revised: 10 January 2014 / Accepted: 16 January 2014 / Published: 28 January 2014
Cited by 35 | PDF Full-text (3321 KB) | HTML Full-text | XML Full-text
Abstract
In the past two decades, we have witnessed significant progress in developing high performance stimuli-responsive polymeric materials. This review focuses on recent developments in the preparation and application of patterned stimuli-responsive polymers, including thermoresponsive layers, pH/ionic-responsive hydrogels, photo-responsive film, magnetically-responsive composites, electroactive [...] Read more.
In the past two decades, we have witnessed significant progress in developing high performance stimuli-responsive polymeric materials. This review focuses on recent developments in the preparation and application of patterned stimuli-responsive polymers, including thermoresponsive layers, pH/ionic-responsive hydrogels, photo-responsive film, magnetically-responsive composites, electroactive composites, and solvent-responsive composites. Many important new applications for stimuli-responsive polymers lie in the field of nano- and micro-fabrication, where stimuli-responsive polymers are being established as important manipulation tools. Some techniques have been developed to selectively position organic molecules and then to obtain well-defined patterned substrates at the micrometer or submicrometer scale. Methods for patterning of stimuli-responsive hydrogels, including photolithography, electron beam lithography, scanning probe writing, and printing techniques (microcontact printing, ink-jet printing) were surveyed. We also surveyed the applications of nanostructured stimuli-responsive hydrogels, such as biotechnology (biological interfaces and purification of biomacromoles), switchable wettability, sensors (optical sensors, biosensors, chemical sensors), and actuators. Full article
(This article belongs to the Section Advanced Composites)
Open AccessReview Electrospun Polymer Fibers for Electronic Applications
Materials 2014, 7(2), 906-947; doi:10.3390/ma7020906
Received: 24 December 2013 / Revised: 21 January 2014 / Accepted: 23 January 2014 / Published: 28 January 2014
Cited by 8 | PDF Full-text (1680 KB) | HTML Full-text | XML Full-text
Abstract
Nano- and micro- fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within [...] Read more.
Nano- and micro- fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within thin films. Moreover, they open the way to many applications in organic electronics, optoelectronics and sensing. Electro-spinning, the technique subject of this review, is a simple method to effectively form and control conjugated polymer fibers. We provide the basics of the technique and its recent advancements for the formation of highly conducting and high mobility polymer fibers towards their adoption in electronic applications. Full article
(This article belongs to the Special Issue Conjugated Polymers)
Open AccessReview Wear Debris Characterization and Corresponding Biological Response: Artificial Hip and Knee Joints
Materials 2014, 7(2), 980-1016; doi:10.3390/ma7020980
Received: 30 October 2013 / Revised: 3 December 2013 / Accepted: 10 December 2013 / Published: 10 February 2014
Cited by 19 | PDF Full-text (5840 KB) | HTML Full-text | XML Full-text
Abstract
Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize [...] Read more.
Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials. Full article
(This article belongs to the Section Structure Analysis and Characterization)
Open AccessReview Nanocomposite Electrospun Nanofiber Membranes for Environmental Remediation
Materials 2014, 7(2), 1017-1045; doi:10.3390/ma7021017
Received: 22 November 2013 / Revised: 14 January 2014 / Accepted: 15 January 2014 / Published: 10 February 2014
Cited by 19 | PDF Full-text (999 KB) | HTML Full-text | XML Full-text
Abstract
Rapid worldwide industrialization and population growth is going to lead to an extensive environmental pollution. Therefore, so many people are currently suffering from the water shortage induced by the respective pollution, as well as poor air quality and a huge fund is [...] Read more.
Rapid worldwide industrialization and population growth is going to lead to an extensive environmental pollution. Therefore, so many people are currently suffering from the water shortage induced by the respective pollution, as well as poor air quality and a huge fund is wasted in the world each year due to the relevant problems. Environmental remediation necessitates implementation of novel materials and technologies, which are cost and energy efficient. Nanomaterials, with their unique chemical and physical properties, are an optimum solution. Accordingly, there is a strong motivation in seeking nano-based approaches for alleviation of environmental problems in an energy efficient, thereby, inexpensive manner. Thanks to a high porosity and surface area presenting an extraordinary permeability (thereby an energy efficiency) and selectivity, respectively, nanofibrous membranes are a desirable candidate. Their functionality and applicability is even promoted when adopting a nanocomposite strategy. In this case, specific nanofillers, such as metal oxides, carbon nanotubes, precious metals, and smart biological agents, are incorporated either during electrospinning or in the post-processing. Moreover, to meet operational requirements, e.g., to enhance mechanical stability, decrease of pressure drop, etc., nanofibrous membranes are backed by a microfibrous non-woven forming a hybrid membrane. The novel generation of nanocomposite/hybrid nanofibrous membranes can perform extraordinarily well in environmental remediation and control. This reality justifies authoring of this review paper. Full article
(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles 2013)
Open AccessReview Colorimetric Sugar Sensing Using Boronic Acid-Substituted Azobenzenes
Materials 2014, 7(2), 1201-1220; doi:10.3390/ma7021201
Received: 30 November 2013 / Revised: 13 January 2014 / Accepted: 28 January 2014 / Published: 14 February 2014
Cited by 13 | PDF Full-text (479 KB) | HTML Full-text | XML Full-text
Abstract
In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. [...] Read more.
In association with increasing diabetes prevalence, it is desirable to develop new glucose sensing systems with low cost, ease of use, high stability and good portability. Boronic acid is one of the potential candidates for a future alternative to enzyme-based glucose sensors. Boronic acid derivatives have been widely used for the sugar recognition motif, because boronic acids bind adjacent diols to form cyclic boronate esters. In order to develop colorimetric sugar sensors, boronic acid-conjugated azobenzenes have been synthesized. There are several types of boronic acid azobenzenes, and their characteristics tend to rely on the substitute position of the boronic acid moiety. For example, o-substitution of boronic acid to the azo group gives the advantage of a significant color change upon sugar addition. Nitrogen-15 Nuclear Magnetic Resonance (NMR) studies clearly show a signaling mechanism based on the formation and cleavage of the B–N dative bond between boronic acid and azo moieties in the dye. Some boronic acid-substituted azobenzenes were attached to a polymer or utilized for supramolecular chemistry to produce glucose-selective binding, in which two boronic acid moieties cooperatively bind one glucose molecule. In addition, boronic acid-substituted azobenzenes have been applied not only for glucose monitoring, but also for the sensing of glycated hemoglobin and dopamine. Full article
(This article belongs to the Special Issue Functional Materials and Proteins for Bio-Sensing Applications)
Open AccessReview Review of Plasmonic Nanocomposite Metamaterial Absorber
Materials 2014, 7(2), 1221-1248; doi:10.3390/ma7021221
Received: 19 December 2013 / Revised: 28 January 2014 / Accepted: 7 February 2014 / Published: 14 February 2014
Cited by 29 | PDF Full-text (1069 KB) | HTML Full-text | XML Full-text
Abstract
Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon). These rationally designed structures have spurred interest noticeably since they [...] Read more.
Plasmonic metamaterials are artificial materials typically composed of noble metals in which the features of photonics and electronics are linked by coupling photons to conduction electrons of metal (known as surface plasmon). These rationally designed structures have spurred interest noticeably since they demonstrate some fascinating properties which are unattainable with naturally occurring materials. Complete absorption of light is one of the recent exotic properties of plasmonic metamaterials which has broadened its application area considerably. This is realized by designing a medium whose impedance matches that of free space while being opaque. If such a medium is filled with some lossy medium, the resulting structure can absorb light totally in a sharp or broad frequency range. Although several types of metamaterials perfect absorber have been demonstrated so far, in the current paper we overview (and focus on) perfect absorbers based on nanocomposites where the total thickness is a few tens of nanometer and the absorption band is broad, tunable and insensitive to the angle of incidence. The nanocomposites consist of metal nanoparticles embedded in a dielectric matrix with a high filling factor close to the percolation threshold. The filling factor can be tailored by the vapor phase co-deposition of the metallic and dielectric components. In addition, novel wet chemical approaches are discussed which are bio-inspired or involve synthesis within levitating Leidenfrost drops, for instance. Moreover, theoretical considerations, optical properties, and potential application of perfect absorbers will be presented. Full article
(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Particles 2013)
Open AccessReview Liquid-Crystal-Enabled Active Plasmonics: A Review
Materials 2014, 7(2), 1296-1317; doi:10.3390/ma7021296
Received: 17 January 2014 / Revised: 1 February 2014 / Accepted: 12 February 2014 / Published: 18 February 2014
Cited by 35 | PDF Full-text (1303 KB) | HTML Full-text | XML Full-text
Abstract
Liquid crystals are a promising candidate for development of active plasmonics due to their large birefringence, low driving threshold, and versatile driving methods. We review recent progress on the interdisciplinary research field of liquid crystal based plasmonics. The research scope of this [...] Read more.
Liquid crystals are a promising candidate for development of active plasmonics due to their large birefringence, low driving threshold, and versatile driving methods. We review recent progress on the interdisciplinary research field of liquid crystal based plasmonics. The research scope of this field is to build the next generation of reconfigurable plasmonic devices by combining liquid crystals with plasmonic nanostructures. Various active plasmonic devices, such as switches, modulators, color filters, absorbers, have been demonstrated. This review is structured to cover active plasmonic devices from two aspects: functionalities and driven methods. We hope this review would provide basic knowledge for a new researcher to get familiar with the field, and serve as a reference for experienced researchers to keep up the current research trends. Full article
(This article belongs to the Special Issue Liquid Crystals) Print Edition available
Open AccessReview Review of the Potential of the Ni/Cu Plating Technique for Crystalline Silicon Solar Cells
Materials 2014, 7(2), 1318-1341; doi:10.3390/ma7021318
Received: 4 December 2013 / Revised: 21 January 2014 / Accepted: 10 February 2014 / Published: 18 February 2014
Cited by 22 | PDF Full-text (968 KB) | HTML Full-text | XML Full-text
Abstract
Developing a better method for the metallization of silicon solar cells is integral part of realizing superior efficiency. Currently, contact realization using screen printing is the leading technology in the silicon based photovoltaic industry, as it is simple and fast. However, the [...] Read more.
Developing a better method for the metallization of silicon solar cells is integral part of realizing superior efficiency. Currently, contact realization using screen printing is the leading technology in the silicon based photovoltaic industry, as it is simple and fast. However, the problem with metallization of this kind is that it has a lower aspect ratio and higher contact resistance, which limits solar cell efficiency. The mounting cost of silver pastes and decreasing silicon wafer thicknesses encourages silicon solar cell manufacturers to develop fresh metallization techniques involving a lower quantity of silver usage and not relying pressing process of screen printing. In recent times nickel/copper (Ni/Cu) based metal plating has emerged as a metallization method that may solve these issues. This paper offers a detailed review and understanding of a Ni/Cu based plating technique for silicon solar cells. The formation of a Ni seed layer by adopting various deposition techniques and a Cu conducting layer using a light induced plating (LIP) process are appraised. Unlike screen-printed metallization, a step involving patterning is crucial for opening the masking layer. Consequently, experimental procedures involving patterning methods are also explicated. Lastly, the issues of adhesion, back ground plating, process complexity and reliability for industrial applications are also addressed. Full article
(This article belongs to the Special Issue Solar Energy Materials 2013)

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