Mg 2+-doped GaN nanoparticles as blue-light emitters: a method to avoid sintering at high temperatures

Bright blue-light emission at 410 nm is observed from Mg(2+)-doped GaN nanoparticles prepared by the nitridation of Ga(2)MgO(4) nanoparticles at 950 degrees C. The sintering of these nanoparticles during high-temperature nitridation was prevented by mixing the Ga(2)MgO(4) precursor nanoparticles with La(2)O(3) as an inert matrix before the nitridation process. The Mg(2+)-doped GaN nanoparticles were isolated from the matrix by etching with 10 % nitric acid. The Mg(2+)-doped GaN nanoparticles were characterized by photoluminescence, atomic force microscopy, X-ray diffraction, and IR analyses.     

Effect of hydrogen addition on criteria and greenhouse gas emissions for a marine diesel engine

Hydrogen remains an attractive alternative fuel to petroleum and a number of investigators claim that adding hydrogen to the air intake manifold of a diesel engine will reduce criteria emissions and diesel fuel consumption. Such claims are appealing when trying to simultaneously reduce petroleum consumption, greenhouse gases and criteria pollutants. The goal of this research was to measure the change in criteria emissions (CO, NO_x, and PM_2.5) and greenhouse gases such as carbon dioxide (CO₂), using standard test methods for a wide range of hydrogen addition rates. A two-stroke Detroit Diesel Corporation 12V-71TI marine diesel engine was mounted on an engine dynamometer and tested at three out of the four loads specified in the ISO 8178-4 E3 emission test cycle and at idle. The engine operated on CARB ultra-low sulfur #2 diesel with hydrogen added at flow rates of 0, 22 and 220 SLPM.     

Characterization of electroplated FeSe thin films

Thin films of iron selenide (FeSe) were electrodeposited on tin oxide coated conducting glass substrates at various bath temperatures, deposition potential and solution pH values. The deposited films were characterized by X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy and optical absorption techniques, respectively. The structure was found to be hexagonal with preferential orientation along {002} plane. X-ray line profile analysis technique by the method of variance has been used to evaluate the microstructural parameters. The variation of microstructural parameters with bath temperature, deposition potential and solution pH values were studied. The observed results are discussed in detail.     

Effect of nanoparticle on emission and performance characteristics of a diesel engine fueled with cashew nut shell biodiesel

High-rise in the air pollution levels due to combustion of the fossil fuel gives us the opportunity to discover environmentally friendly and clean fuels for the engines. Biodiesel originated from cashew nut shell oil through transesterification process can be blended or used as a neat fuel in unmodified engines. This work investigates the effect of alumina nanoparticles on emission and performance characteristics of cashew nut shell biodiesel. Neat cashew nut shell biodiesel prepared by conventional transesterification is termed as BD100 and biodiesel prepared by modified transesterification with the addition of alumina nanoparticles is termed as BD100A. Experimental results on unmodified diesel engine revealed that emission parameters such as CO, HC, NOx, and smoke were decreased by 5.3%, 7.4%, 10.23%, and 16.1% for BD100% and 8.8%, 10.1%, 12.4%, and 18.4% for B100A, respectively, compared to diesel fuel. At full load conditions, compared to diesel fuel, the BTE dropped by 1.1% and 2.3%, whereas the BSFC increased by 3.8% and 5.1% for B100A and B100 correspondingly.     

A Fuzzy Optimization Approach for Variation Aware Power Minimization During Gate Sizing

Technology scaling in the nanometer era has increased the transistor's susceptibility to process variations. The effects of such variations are having a huge impact on the yield of the integrated circuits and need to be considered early in the design flow. Traditional corner based deterministic methods are no longer effective and circuit optimization methods require reinvention with a statistical perspective. In this paper, we propose a new gate sizing algorithm using fuzzy linear programming in which the uncertainty due to process variations is modeled using fuzzy numbers. The variations in gate delay which is a function of the gate sizes and the fan-outs of the gates are represented using triangular fuzzy numbers with linear membership functions. Initially, as a preprocessing step for fuzzy optimization, we perform deterministic optimizations by fixing the fuzzy parameters to the worst and the average case values, the results of which are used to convert the fuzzy optimization problem into a crisp nonlinear problem. The crisp problem with delay and power as constraints is then formulated to maximize the robustness, i.e., the variation resistance of the circuit. The fuzzy optimization approach was tested on ITC'99 benchmark circuits and the results were validated for timing yield using Monte Carlo simulations. The proposed approach is shown to achieve better power reduction than the worst case deterministic optimization as well as the stochastic programming based gate sizing methods, while having comparable runtimes.     

InAs/InGaSb photodetectors grown on GaAs bonded substrates

The results of wafer fusion between GaAs and InP followed by transfer of an InGaAs film from the InP to GaAs substrate are presented in this paper. This technique of film transfer allowed the subsequent growth of epitaxial materials with approximately 7% lattice mismatch. Type-II InAs/GaInSb superlattices photodetectors of different designs have been grown by molecular beam epitaxy (MBE) on the alternative InGaAs/GaAs substrate and on standard GaSb substrates. Comparison between photodetectors grown on the two different substrates with nearly identical superlattice periods showed a shift in the cut-off wavelength. The superlattices grown on the alternative substrates were found to have uniform layers, with broader x-ray linewidths than superlattices grown on GaSb substrates.     

Ag/TiO2/bentonite nanocomposite for biological applications: Synthesis,characterization, antibacterial and cytotoxic investigations

Bentonite (bent) clay supported silver (Ag)/titanium dioxide (TiO₂) nanocomposite material was green synthesized by facile thermal decomposition method in the absence of reducing and precipitating agents. The samples were characterized by XRD, BET, HR-SEM with EDX mapping, TEM with SAED patterns, XPS, PSA, FT-IR, and UV–Vis DRS. XRD and EDX spectra showed peaks of Ag and TiO₂, confirming the formation of the Ag/TiO₂ nanoparticles in the composite. TEM revealed the uniform distribution of Ag/TiO₂ nanoparticles cluster on the surface of the bent with an average size of ～5 to 50 nm. The antibacterial activities of Na-bent, Ag, TiO₂, and Ag/TiO₂/bent nanocomposite samples were tested against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria by the well diffusion method. Furthermore, the cytotoxicity of Ag/TiO₂/bent nanocomposite material was determined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Also, the succinate-dehydrogenase release showed the nontoxic nature of the nanocomposite at low concentrations. The cytotoxicity results of samples were evaluated using human embryonic kidney cell line (HEK 293) and have given excellent biocompatibility and cell proliferation in the in vitro studies.     

Determination of structural and optical parameters of CuO thin films prepared by double dip technique

Cupric oxide (CuO) thin films are deposited on glass substrates by double dip method at various molar concentrations of copper sulphate salt. Growth mechanism is derived using oxolation process. The structural studies revealed the deposited films exhibited polycrystalline nature with monoclinic structure. The change in the molar concentration of copper sulphate salt has pronounced effect on the microstructural properties of deposited thin films. XPS and EDS spectra confirm the presence of Cu and O. Micro Raman spectra shows two A_g and B_g active Raman mode peaks corresponding to CuO phase. Deposited films showed a high absorbance in the visible range with the bandgap value of 1.3 eV making it a suitable material as semiconductor tandem absorber for solar cells. Optical constants such as refractive index (n), extinction coefficient (k), optical conductivity (σ) and dielectric constants (ε) were evaluated using an approximation protocol developed from well recognized procedures using the data obtained from UV spectroscopic technique. The prepared CuO thin films are identified as suitable candidates for optoelectronic devices and solar cell fabrication.     

Designing of multiple deferred state sampling plan for generalized inverted exponential distribution

In this article, we propose a sampling plan called a multiple deferred state sampling plan for sentencing a lot based on the information of current and successive lot samples. Based on this sampling plan, the median life of the product is assured based on a time-truncated life test where the lifetime of the product follows the generalized inverted exponential distribution. The quality of the product is measured by its median life. The optimal parameters of the proposed plan are obtained by using the approach of two points on the operating characteristic curve. Tables are also constructed for determining the optimal parameters with various shape parameters. The implementation of the proposed plan is illustrated with examples. The performance of the proposed plan is compared with the performance of existing sampling plans under the generalized inverted exponential distribution.     

Structural and optical properties of electrodeposited indium selenide thin films

Journal of Materials Science Letters -