Lateral trench oxide Schottky rectifier on SOI for power integrated circuits

In this paper, a Lateral Trench Oxide Schottky (LTOS) rectifier on silicon-on-insulator suitable for power integrated circuits is presented. The proposed structure utilizes a surface Schottky contact with vertical field-plate placed in a trench filled with oxide. The field-plate reduces the electric field on the Schottky contact and suppresses the barrier lowering effect leading to significant improvement in the device performance. Further, the proposed structure folds the drift region in vertical and horizontal directions resulting substantial reduction in pitch length of the device. Two-dimensional numerical simulations have been performed to analyse and optimize the performance of proposed device and results are compared with that of the conventional lateral Schottky rectifier. The LTOS rectifier provides 60 % improvement in breakdown voltage and 50 % reduction in pitch length as compared to the conventional device while maintaining low forward voltage drop and low reverse leakage current.     

Electrical characterization and parameter extraction of organic thin film transistors using two dimensional numerical simulations

In this paper a performance based comparison of top and bottom contact organic thin film transistor (OTFT) device structures, using two dimensional numerical simulations has been carried out. In addition to this, investigations pertaining to the estimation of contact resistance in these OTFTs were also performed. To estimate contact resistance the conventional transmission line method and modified transmission line method (M-TLM) were respectively invoked. Our simulation results clearly indicate that the latter is more accurate in the estimation of contact resistance compared to the conventional method. Furthermore, the M-TLM was used to estimate the gate voltage and film thickness dependence of the contact resistance for the two device structures. The observed results have been explained on the basis of the significantly lowered area of carrier injection and extraction regions, at the source/channel and channel/drain interface respectively, in bottom contact transistor that lead to its inferior performance over the top contact transistor.     

Acid Diffusion into Rice Boluses is Influenced by Rice Type,Variety, and Presence of α‐Amylase

Breakdown of rice during gastric digestion may be influenced by rice structure, presence of salivary α‐amylase, and hydrolysis by gastric acid. During mastication, saliva is mixed with rice, allowing α‐amylase to begin starch hydrolysis. This hydrolysis may continue in the gastric environment depending on the rate at which gastric acid penetrates into the rice bolus. The objective of this study was to determine the acid uptake into rice boluses with and without α‐amylase in saliva. Two types each of brown and white rice (medium and long grain), were formed into a cylindrical‐shaped bolus. Each bolus was sealed on all sides except one to allow one‐dimensional mass transfer, and incubated by immersion in simulated gastric juice at 37 °C under static conditions. Acidity of the boluses was measured by titration after 1 to 96 h of incubation. Effective diffusivity of the gastric juice through the bolus was estimated using MATLAB. Average acidity values ranged from 0.04 mg HCl/g dry matter (medium grain white rice, no incubation) to 10.01 mg HCl/g dry matter (long‐grain brown rice, 72 h incubation). The rice type, presence of α‐amylase, and incubation time all significantly influenced rice bolus acidity (P < 0.001). Effective diffusivity of gastric juice into the bolus was greater in brown rice than in white rice. These results indicate that starch hydrolysis by α‐amylase may continue in the stomach before the gastric acid penetrates the rice bolus, and the rate of acid uptake will depend on the type of rice consumed.     

Antioxidant activity and protective effect against plasmid DNA strand scission of leaf, bark, and heartwood extracts from Acacia catechu

The antioxidant activity of methanol extract/fractions of leaf, bark, and heartwood of Acacia catechu was evaluated by various antioxidant assays, including free radical, superoxide and hydroxyl radical, reducing power, metal ion chelation, as well as hydroxyl radical induced DNA strand scission. The leaf, bark, and heartwood powder was extracted in methanol and the lyophilized methanol extract was fractionated with different solvents in the order of increasing polarity. The results indicate that ethyl acetate fraction of heartwood has the highest antioxidant capacities, presenting lower EC(50) values particularly in free radical scavenging activity, including DPPH radicals (4.76 ± 0.14 μg/mL), superoxide anions (26.21 ± 0.79 μg/mL), and hydroxyl radicals (33.69 ± 1.42 μg/mL), in direct assay systems. Reducing power was also highest in ethyl acetate fraction of heartwood (EC(50) of 79.05 ± 1.02 μg/mL). As for the chelating power on ferrous ions, leaf extract was more effective than bark and heartwood extracts. Furthermore, the ethyl acetate and acetone fractions of heartwood significantly protected pBR322 supercoiled plasmid DNA against strand scission induced by hydroxyl radicals in a Fenton's reaction mixture. PRACTICAL APPLICATION: The present investigation suggests that the three organs of A. catechu differ significantly in their antioxidant potential as seen in the DPPH radical scavenging assay, reducing power assay, metal ion chelating assay, superoxide radical scavenging assay and hydroxyl radical scavenging assay. Further, our results showed that crude methanol extract and ethyl acetate fraction of heartwood of A. catechu might have a good potential as a source for natural health products due to its antioxidant and DNA protective activities.     

Significance of Hall effect on heat and mass transport of titanium alloy-water-based nanofluid flow past a vertical surface with IMF effect

In this mathematical presentation, we examined the significance of Hall current on MHD buoyancy-driven boundary layer flow of a Ti₆Al₄V-H₂O based nanofluid past a vertical surface implanted in a uniform permeable region. The vertical surface is considered to be magnetized and induced magnetic field (IMF) impacts are also considered. The nondimensional flow model is solved with the assistance of the two-term perturbation scheme. Various results are obtained by numerical computation for different significant parameters. These results are presented and analyzed in graphical and tabular form. In the boundary layer domain, the transpiration velocity across the surface tends to diminish the main flow, IMF along the main flow, fluid temperature, and concentration. It is remarkably noted that IMF along the main flow grows for incrementing values of volume fraction coefficient of nanofluid. In the magnetic boundary layer domain, the main flow and IMF along the main flow grow with Hall current. Furthermore, it is seen that for the progressing values of magnetic Prandtl number, the main flow reduces while normal flow and IMF along the main flow is induced in the boundary layer domain.     

Application of response surface methodology to optimize diesel engine parameters fuelled with pongamia biodiesel/diesel blends

ABSTRACT

In the present scenario, the rate of fossil fuel consumption is very high and increasing rapidly which lead to a further increase in air pollution levels. Due to an increase in pollution level, researchers are striving to discover some cleaner and environment-friendly fuels for the diesel engines. This study was focused on the optimization of the input parameters of the diesel engine running on pongamia biodiesel for improvement in the engine performance. The input parameters selected for optimization were fuel injection pressure, fuel injection timing, pongamia biodiesel blends, and engine load with respect to BTE, BSFC, exhaust gas temperature, and P_max. An experimental analysis was performed according to the response surface methodology technique. The best engine input parameters setting for getting optimum performance was found at fuel injection timing 25 bTDC, fuel injection pressure 226 bar, 40% of pongamia biodiesel blending, at 74% of maximum rated engine load. Experimental and optimized results of the output responses at optimum input parameters were compared and found in the suggested error range.     

Electricity generation using solar parabolic dish system with thermoelectric generator—An experimental investigation

The present electricity grid installation cost as well as the tariff is quite high in India, particularly remote rural areas, to electrify houses. These problems can be easily solved by installing standalone systems that operate on one of the clean energy sources such as solar energy. An experimental analysis of generating electricity from a thermoelectric generator (TEG) powered by a solar parabolic dish concentrator device with aperture area and focal length of 12.6 m² and 2.42 m, respectively, is presented in this article. A TEG is made up of a thermoelectric module connected to a flat receiver by an absorber layer. The studies were carried out in Indian climatic conditions at the National Institute of Technology, Puducherry. Over a spectrum of beam radiation, the system's maximum energy conversion efficiency, as well as efficient electrical output, are evaluated and presented. The proposed system's average effective electrical efficiency is 0.424%, corresponding to the TEG's average energy conversion efficiency of 2.76%.     

Heat and mass transport performance of MHD elastico-viscous fluid flow over a vertically oriented magnetized surface with magnetic and thermo diffusions

The key objective in this study is to examine the heat and mass transport behavior of magnetohydrodynamic elastic-viscous fluid flow over a vertically oriented magnetized surface placed in a uniform permeable regime with magnetic and thermo diffusions. The fluid is partially ionized and permeated to flow in the presence of a strong magnetic field domain. Hence the Hall current effect is considered in this investigation. The significance of rotation and induced magnetic field on the flowing nature are also scrutinized in this study. The mathematical model of the problem is converted to a similar model by introducing suitable nondimensional variables. To obtain the closed-form solutions of the flow leading equations, the regular perturbation analysis is utilized. For the exhibition of results, figures and tables are generated with the assistance of scientific computation software MATHEMATICA. Computed results are validated with the existing result in the limiting case. Such an investigation is important in evaluating the flow characteristics of low magnetic diffusive viscoelastic fluid. A noteworthy result seen is that magnetic diffusion significantly controls the fluid flow by altering the magnetic drag force. Mass diffusion factor brings an increase in the fluid velocity. Furthermore, we observed that the surface current density along the principal flow direction is significantly reduced by magnetic diffusion and mass diffusion factor.