The Preparation and Characterization of Silk/Gelatin Biocomposites

There is a growing interest in the use of composite materials. Silk fiber/gelatin biocomposites were fabricated using compression molding. The fiber content in the composite varied from 10–30 wt%. Composite containing 30 wt% silk showed the best mechanical properties. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength, hardness of the 30% silk content composites were found 54 MPa, 0.95 GPa, 75 MPa and 0.43 GPa and 5.4 kJ/m², 95.5 Shore A, respectively. Water uptake properties at room temperature, accelerated weathering aging, irradiation, thermomechanical analysis, and degradation in soil were carried out in this experiment.     

Electrophoretic Deposition Kinetics and Characterization of Ni–La1.95Ca0.05Zr2O7−δ Particulate Thin Films

Suspensions of NiO–La_1.95Ca_0.05Zr₂O_7?δ (NiO–LCZ) composite material have been prepared in isopropanol medium using iodine and acetylacetone as dispersants. The effect of iodine concentration on suspension stability, electrical conductivity, and suspension pH are studied in detail to optimize the suspension chemistry. Electrophoretic deposition has been successfully conducted on conducting substrate (steel plate) to fabricate NiO–LCZ thin particulate films. Deposition kinetics have been studied in detail to optimize the process parameters. Good quality particulate films of such composite on steel plates are obtained at an applied voltage of 60 V for 3 min. The optimized suspension chemistry and process parameters thus obtained are then used to fabricate NiO–LCZ composite films onto nonconducting porous ceramic substrate by placing a conducting plate at the reverse side of the porous substrate. The deposited films along with the ceramic substrates are co‐fired at 1400°C for 6 h in reducing atmosphere (5% hydrogen in argon) to produce a good quality dense Ni–LCZ film of thickness ~40 μm. The hydrogen permeation flux of the developed cermet membrane has been measured and it reveals that Ni–LCZ could be used as a potential membrane for hydrogen separation at high temperature.     

Processing and Performance of MOF (Metal Organic Framework)-Loaded PAN Nanofibrous Membrane for CO<Subscript>2</Subscript> Adsorption

The objective of this experimental study is to produce a nanofibrous membrane functionalized with adsorbent particles called metal organic framework (MOF) in order to adsorb CO₂ from a gas source. Therefore, Polyacrylonitrile (PAN) was chosen as the precursor for nanofibers and HKUST-1, a Cu-based MOF, was chosen as adsorbent. The experimental process consists of electrospinning PAN solution blended with HKUST-1 to produce a nanofibrous mat as working substrates. The fibers were collected in a cylindrical canister model. SEM image of this mat showed nanofibers with the presence of small adsorbent particles, impregnated into the as-spun fibers discretely. To increase the amount of MOF particles for effectual gas adsorption, a secondary solvothermal process of producing MOF particles on the fibers was required. This process consists of multiple growth cycles of HKUST-1 particles by using a sol-gel precursor. SEM images showed uniform distribution of porous MOF particles of 2-4 µm in size on the fiber surface. Energy dispersive spectroscopy report of the fiber confirmed the presence of MOF particles through the identification of characteristic Copper elemental peaks of HKUST-1. To determine the thermal stability of the fibrous membrane, Thermogravimetric analysis of HKUST-1 consisting of PAN fiber was performed where a total weight loss of 40% between 210 and 360 °C was observed, hence proving the high-temperature durability of the synthesized membrane. BET surface area of the fiber membrane was measured as 540.73 m²/g. The fiber membrane was then placed into an experimental test bench containing a mixed gas inflow of CO₂ and N₂. Using non-dispersive infrared CO₂ sensors connected to the inlet and outlet port of the bench, significant reduction of CO₂ in concentration was measured. Comparative IR spectroscopic analysis between the gas-treated and gas untreated fiber samples showed the presence of characteristic peak in the vicinity of 2300 and 2400 cm^?1 which verifies the adsorption of CO₂.     

Effects of tin particles addition on structural and mechanical properties of eutectic Sn–58Bi solder joint

Due to the inherent environmental and health toxicities associated with lead, the use of environmental friendly lead-free solder materials has become an unavoidable trend in the electronic packaging industry. Sn-58Bi alloy is gaining attention for its good material properties such as low melting point, reliability and high tensile strength. The presence of the bismuth-rich phase increases the brittleness of Sn-58Bi alloy. The purpose of this study is to suppress the brittleness of Sn-58Bi alloy by the addition of different wt% (0, 10, 20, 30) of Sn powder. The powder metallurgy method was used to prepare the samples. Scanning electron microscopy and energy-dispersive X-ray analysis were done to study the structural properties and a tensile test was done by a universal tensile machine to study the mechanical properties. The results reveal that the Sn particles partially dissolved in the Sn-58Bi solder matrix. The dissolution of Sn particles significantly improved the mechanical strength by 30%, suppressed the brittleness and improved the strain value by 1.3 times.

     

Simulation of thin-TFETs using transition metal dichalcogenides: effect of material parameters,gate dielectric on electrostatic device performance

In recent years, significant of scientific research effort has focused on the investigation of transition metal dichalcogenides (TMDC) and other two-dimensional (2D) materials like graphene or boron nitride. Theoretical investigation on the physical aspects of these materials has revealed a whole new range of exciting applications due to wide tunability in electronic and optoelectronic properties. Besides theoretical exploration, these materials have been successfully implemented in electronic and optoelectronic devices with promising results. In this work, we have investigated the effect of monolayer TMDC materials and monolayer TMDC alloys on the performance of thin tunneling field-effect transistors or thin-TFETs. These are promising electronic devices that can achieve steep switching characteristics. We have used the self-consistent determination of the conduction and valence band levels in the device and a simplified model of interlayer tunneling current reported in recent literature that treats scattering semiclassically and incorporates the energy broadening effect using a Gaussian approximation . We have also explored the effect of gate dielectric material variation, interlayer dielectric variation, top gate metal workfunction on the performance of the device. Our study shows that proper choice of material in the top and bottom layers, optimization of materials used as gate and interlayer dielectric are necessary to extract the full potential of these devices. The electron affinity and bandgap of the TMDCs used in different layers effectively control the threshold voltage and current in the device. As seen from our simulation, interlayer materials with high dielectric constant can degrade subthreshold device performance, increase threshold voltage, whereas lowering interlayer thickness could increase device ‘on’ current at the expense of degraded subthreshold performance.     

Laser Composite Surfacing of Ni-WC Coating on AA5083 for Enhancing Tribomechanical Properties

Laser composite surfacing (LCS) has emerged as an alternative photon-driven manufacturing technology for the fabrication of composite coatings to enhance the tribomechanical properties of various aluminum alloys. The current research presents an analysis on optimization of laser processing parameters for Ni-WC composite coating deposited on AA5083 aluminum alloy in order to improve its tribomechanical properties. To carry out the investigation, Taguchi's optimization method using a standard L₁₆ (3⁴) orthogonal array was employed. Thereafter, the results were analyzed using signal-to-noise (S/N) ratio response analysis and Pareto analysis of variance (ANOVA). Finally, confirmation tests with the best parameter combinations obtained in the optimization process were made to demonstrate the progress made. Results showed that the surface hardness (953 H_v) and roughness (0.81 μm) of coated AA5083 samples was enhanced by 9.27 and 13.14%, respectively. The tribological behavior of LCS samples was investigated using a ball-on-plate tribometer against a counterbody of 440c steel. It was revealed that the wear of the Ni-WC-coated samples improved by around 2.5 times. For lower applied loads, the coating exhibited an abrasive wear mode and a reduction in plastic deformation.     

Impact of high‐κ gate dielectric and other physical parameters on the electrostatics and threshold voltage of long channel gate‐all‐around nanowire transistor

High‐κ gate‐all‐around structure counters the Short Channel Effect (SCEs) mostly providing excellent off‐state performance, whereas high mobility III–V channel ensures better on‐state performance, rendering III–V nanowire GAAFET a potential candidate for replacing the current FinFETs in microchips. In this paper, a 2D simulator for the III–V GAAFET based on self‐consistent solution of Schrodinger–Poisson equation is proposed. Using this simulator, capacitance–voltage profile and threshold voltage are characterized, which reveal that gate dielectric constant (κ) and oxide thickness do not affect threshold voltage significantly at lower channel doping. Moreover, change in alloy composition of In_xGa_1‐xAs, channel doping, and cross‐sectional area has trivial effects on the inversion capacitance although threshold voltage can be shifted by the former two. Although, channel material also affects the threshold voltage, most sharp change in threshold voltage is observed with change in fin width of the channel (0.005 V/nm for above 10 nm fin width and 0.064 V/nm for sub‐10 nm fin width). Simulation suggests that for lower channel doping below 10²³ m⁻³, fin width variation affects the threshold voltage most. Whereas when the doping is higher than 10²³ m⁻³, both the thickness and dielectric constant of the oxide material have strong effects on threshold voltage (0.05 V/nm oxide thickness and 0.01 V/per unit change in κ). Copyright © 2014 John Wiley & Sons, Ltd.     

Semiconductor-ionic properties and device performance of heterogeneous La-doped CeO2-ZnO nanocomposites

Heterogeneous La-doped CeO₂ (LCO)-ZnO nanocomposites have been synthesized via a facile wet-chemical approach for multifunctional applications. It is found that such LCO-ZnO with the Zn/Ce ratio of 9:1 demonstrates the highest photoactivity under visible light irradiation. Apart from the photocatalytic application, this material has also been used as the electrolyte membrane of solid oxide fuel cells (SOFCs). The best device of SOFC composed of 10% LCO-ZnO composite achieved 922 mW cm^-2 output along with an open circuit voltage of 1.10 V at 550 °C. Heterogeneous semiconductor-ionic composite of the heterogeneous LCO-ZnO nanocomposite result in high charge-hole pairs separation and ionic conduction which attributes the efficient multifunctional activity of the synthesized material. The built-in field directed at the junction may promote ions (H⁺ and O^2-) transport to pass through the semiconductor-ionic LCO-ZnO membrane layer. This work is the first discovery on the LCO-ZnO semiconductor-ionic materials as a potential candidate for renewable energies to electricity conversions.     

Financial risk and its impact on new purchasing behavior in the online retail setting

This paper examines the effect of financial risk on perceptions of service quality and relationship-marketing quality in the online retail environment. Perceptions of financial risk were found to be negatively associated with service quality. In particular, a well-designed and attractive Web site was found to mitigate perceptions of financial risk during early trial-buy purchasing. Relationship-marketing quality was not affected by financial risk. This study adds to an enhanced understanding of how risk perceptions influence assessment of service quality and relationship-marketing quality. While the drivers of service quality and relationship-marketing quality have been examined extensively in the online setting, a surprising lack of research investigates the role of risk perceptions in the early stage, buy-trial purchasing behavior. This emerging area of research interest is deserving of more attention. Our findings provide valuable normative guidance to researchers interested in the affects of perceived risk (particularly financial risk) on new online shoppers, emphasizing the interdependency between Web site design and risk perceptions.