Structural,optical and electrical properties of pure and Fe doped V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanoparticles for junction diode fabrications

Structural, optical and electrical studies of V₂O₅ and Fe_xV₂O₅ (x?=?5%) nanostructures synthesized by a wet chemical method have been reported. The synthesized nanostructures were characterized by XRD, SEM–EDX, HRTEM, XPS, UV(DRS), FT-IR, PL, TG–DTA, AC and DC conductivity study’s. The anorthic phase was observed in the XRD patterns of undoped and Fe doped samples which are prepared at low temperature. This anorthic phase was reduced with the heat treatment and gradually transformed into orthorhombic phase in the samples annealed at 600 °C for 1 h. The change in the surface morphology in the present samples from micro-rod to nanorods network seems to be dependent on the substitution of Fe. As observed from the PL analysis that the ultraviolet (UV) emission intensity was found to be decreased and exhibited a blue shift with the increase of Fe concentration. The analysis of AC and DC conductivity measurements recorded at room temperature in the temperature range of 303–403 K, revealed that the activation energy is high for Fe doped V₂O₅ compared to undoped V₂O₅. The junction diodes of n-V₂O₅/p-Si and V₂O₅:Fe/p-Si was successfully prepared by the nebulizer spray pyrolysis method. The (I–V) characteristics of nonlinear and asymmetric nature revealed the Schottky diode based behavior for pure and doped samples.     

An analytical model for a TFET with an n-doped channel operating in accumulation and inversion modes

The tunnel field-effect transistor (TFET) is an ambipolar device that conducts current with the channel in both accumulation and inversion modes. Analytical expressions for the channel potential and current in a TFET with an n-doped channel when operating in the accumulation and inversion modes are proposed herein. The potential model is derived by solving the two-dimensional (2D) Poisson equation using the superposition principle while considering the charges present in the channel due to electron or hole accumulation along with the depletion charges. An expression for the tunneling current corresponding to the maximum tunneling probability is also derived. The tunneling current is obtained by analytically calculating the minimum tunneling length in a TFET when operating in the accumulation or inversion mode. The results of the proposed potential model is compared with technology computer-aided design (TCAD) simulations for TFET with various dimensions, revealing good agreement. The potential and current in an n-type TFET (nTFET) obtained using the proposed models are also analyzed.

     

Temperature-adaptive voltage scaling for enhanced energy efficiency in subthreshold memory arrays

Static random access memory (SRAM) circuits optimized for minimum energy consumption typically operate in the subthreshold regime with ultra low-power-supply voltages. Both the read and the write propagation delays of a subthreshold memory circuit are significantly reduced with an increase in the die temperature. The excessive timing slack observed in the clock period of constant-frequency subthreshold memory circuits at elevated temperatures provides new opportunities to lower the active-mode energy consumption. Temperature-adaptive dynamic supply voltage tuning (TA-DVS) technique is proposed in this paper to reduce the high-temperature energy consumption of ultra low-voltage subthreshold SRAM arrays. Results indicate that the energy consumption can be lowered by up to 32.8% by dynamically scaling the supply voltage at elevated temperatures. The impact of the temperature-adaptive dynamic supply voltage scaling technique on the data stability of the subthreshold SRAM bit-cells is presented. The effectiveness of the TA-DVS technique under process parameter and supply voltage variations is evaluated. An alternative technique based on temperature-adaptive reverse body bias (TA-RBB) to exponentially reduce the subthreshold leakage currents at elevated temperatures is also investigated. The active-mode energy consumption characteristics of the two temperature-adaptive voltage tuning techniques are compared.     

Visual representation and characterization of three-dimensional hydrofracturing cracks within heterogeneous rock through 3D printing and transparent models

International Journal of Coal Science & Technology - The heterogeneity of unconventional reservoir rock tremendously affects its hydrofracturing behavior. A visual representation and accurate...     

Sea buckthorn (Hippophae rhamnoides) proanthocyanidins inhibit in vitro enzymatic hydrolysis of protein

Abstract: Interactions of phenolics with other food constituents and digestive enzymes are likely to have interference with the digestion and bioavailability of food and phenolics. In this study the effect of sea buckthorn proanthocyanidins on in vitro digestion of protein was evaluated. Optimization of the extraction conditions showed that maximum recovery of sea buckthorn proanthocyanidins was obtained with acidified acetone; water mixture (60% to 70%, v/v). Crude proanthocyanidin extracts thus prepared were purified using sephadex gel column chromatography and their average degree of polymerization and the effects on enzymatic hydrolysis of bovine serum albumin as influenced by their protein precipitation capacities were studied. Average degree of polymerization of proanthocyanidins in berry pulp, kernel, seed coat, and leaves was 7.4, 5.6, 8.2, and 10.6, respectively. The EC50 values for the protein precipitation by the PA of berry pulp, kernel seed coat, and leaves were 44.2, 44.1, 65.8, and 39.8 μg, respectively. Relative enzymatic hydrolysis of the protein‐proanthocyanidin complexes was 44.1% to 60.3% for pepsin and 57.5% to 67.7% for trypsin. Interactions of sea buckthorn proanthocyanidins with food proteins and digestive enzymes might alter the protein digestibility and phenolic bioavailabilty.     

Transparent liquid-crystal-based microlens array using vertically aligned carbon nanofiber electrodes on quartz substrates

A novel transparent liquid-crystal-based microlens array has been fabricated using an array of vertically aligned multi-wall carbon nanofibers (MWCNFs) on a quartz substrate and its optical characteristics investigated. Electron beam lithography was used for the catalyst patterning on a quartz substrate to grow the MWCNF array of electrodes. The structure of the electrode array was determined through simulation to achieve the best optical performance. Both the patterned catalyst and growth parameters were optimized for optimal MWCNF properties. We report an in-depth optical characterization of these reconfigurable hybrid liquid crystal and nanofiber microlens arrays.     

Size-controlled synthesis of mesoporous silica nanoparticles using rice husk by microwave-assisted sol–gel method

Mesoporous silica nanoparticles with distinct characteristics like particle size, tunable pores, and high surface area have received much interest for environmental remediation, energy conversion, and biological applications. In this work, we synthesized spherical silica nanoparticles with tunable particle size and mesoporous properties using a low-cost silica source (rice husk) and polyethylene glycol (PEG) via microwave-assisted sol–gel synthesis. The formation of an amorphous silica structure was found using XRD and FTIR analysis. FESEM analysis showed that altering the PEG concentration from .01 to .005 M produced spherical silica nanoparticles with 100–500 nm in size. Nitrogen adsorption–desorption demonstrated that silica nanoparticles obtained with .005, .007, and .01 M of PEG had unique pore sizes and distributions, with specific surface areas of 51.475, 62.367, and 84.251 m²/g, respectively. These results might be due to PEG molecules’ capping effect, which acts as a soft template to regulate particle size, pore size, and dispersion by interacting with sodium silicate precursor. Hence, this approach can be a facile and cost-effective method to prepare mesoporous silica nanoparticles with controllable nanoscale characteristics for suitable applications.