Multidimensional and transient modeling of an alkaline water electrolysis cell

A three-dimensional (3-D) transient numerical model of an alkaline water electrolysis (AWE) cell with potassium hydroxide solution is developed by rigorously accounting for the hydrogen and oxygen evolution reactions and resulting species and charge transport through various AWE components. First, the AWE model is experimentally validated against a polarization curve corresponding to a wide range of currents as high as 2.0 A·cm^?2. In general, the simulation results compare well with the measured data and further reveal the operating characteristics of AWE cells, showing key distributions of solid/electrolyte potentials and multidimensional contours of reactant and product concentrations at various current densities. In particular, the contribution of hydroxide ion (OH^?) diffusion to the ohmic losses through porous electrodes and a porous separator are quantitatively examined at low and high electrolyte flow rates. The present full 3-D AWE model provides a basic understanding of the electrochemical and transport phenomena and can be further applied to practical large-scale AWE cell and stack geometries for grid-scale hydrogen production.     

Hot Deformation Behavior and Microstructural Evolution of Wire-Arc Additively Fabricated Inconel 718 Superalloy

Metallurgical and Materials Transactions A - The hybridization of additive manufacturing techniques with conventional forming processes offers significant reduction in production cost, time, and...     

On ascertaining hardness-microstructure relationship in annealed steel for varying carbon content

Plain carbon steels of five different carbon contents up to eutectoid composition have been provided with the conventional full annealing treatment. Qualitative and quantitative studies of the microstructure are carried out using optical microscopy and field emission scanning electron microscopy techniques. Even under similar cooling rate pertaining to the full annealing treatment (furnace cooling); microstructural modifications of individual microconstituents are feasible with varying chemistry (carbon content) of plain carbon steel. The refinement of microstructure for both proeutectoid α-ferrite and pearlite is found to be accentuated with increasing carbon content of annealed steels till eutectoid composition. Hall-Petch type relationship explains adequately the relationship between hardness and the size of the microconstituent both in terms of the grain size of proeutectoid α-ferrite and the interlamellar spacing of pearlite. Henceforth an empirical relationship is developed for the first time taking into account the rule of mixture to correlate overall hardness, carbon content, grain size of proeutectoid α-ferrite and interlamellar spacing of pearlite. The empirical relationship originated thereby is found to closely match the experimental results.     

3D Printing and Easy Removal of Transparent Thin Polymeric Sheets and their Application in Solar Cells Encapsulation

3D printing of thin transparent sheets is challenging because transparency is compromised due to surface defects. Herein, the 3D printing of thin, transparent, and smooth polymeric surfaces is demonstrated with easy removal and potential application in solar cell encapsulation. Thin disk-shaped objects are printed using a vat-photopolymerization-based 3D-printing technique, and their transparency is measured. The disks are printed directly onto the build plate in three different orientations, whereas a modified build plate is used for each sample. The sample printed on the modified build plate exhibits the highest transparency (≈95%) and is the easiest to remove from the plate. Thin and transparent sheets are prepared with embedded TiO₂ nanoparticles using this approach. TiO₂ addition blocks the ultraviolet-light wavelengths of 200–400 nm, which can reduce phonon generation in silicon solar cells and, thus, lower the panel surface temperature. The results demonstrate an 8 °C reduction in temperature, which can enhance the efficiency of silicon photovoltaics. The proposed method demonstrates the capability of 3D printing of transparent, smooth surfaces with easy removal of thin objects for various applications.     

Variation in oil content and fatty acid composition of the seed oil of Acacia species collected from the northwest zone of India

BACKGROUND: The oil content and fatty acid composition of the mature seeds of Acacia species collected from natural habitat of the northwest zone of the Indian subcontinent (Rajasthan) were analyzed in order to determine their potential for human or animal consumption. RESULTS: Oil content varied between 40 and 102 g kg^?1. The highest oil content was obtained in Acacia bivenosa DC. (102 g kg^?1) among the nine Acacia species. The fatty acid composition showed higher levels of unsaturated fatty acids, especially linoleic acid (～757.7 g kg^?1 in A. bivenosa), oleic acid (～525.0 g kg^?1 in A. nubica) and dominant saturated fatty acids were found to be 192.5 g kg^?1 palmitic acid and 275.6 g kg^?1 stearic acid in A. leucophloea and A. nubica respectively. Seed oils of Acacia species can thus be classified in the linoleic–oleic acid group. Significant variations were observed in oil content and fatty acid composition of Acacia species. CONCLUSION: The present study revealed that the seed oil of Acacia species could be a new source of high linoleic–oleic acid‐rich edible oil and its full potential should be exploited. The use of oil from Acacia seed is of potential economic benefit to the poor native population of the areas where it is cultivated. The fatty acid composition of Acacia seed oils is very similar to that reported for commercially available edible vegetable oils like soybean, mustard, sunflower, groundnut and olive. Hence the seed oil of Acacia species could be a new source of edible vegetable oil after toxicological studies. Copyright © 2012 Society of Chemical Industry     

A study on the synthesis,characterization and properties of polyaniline/magnesium boride nanocomposites

The present paper reports the novel synthesis of polyaniline/magnesium boride (PAni/MgB₂) nanocomposites. Nanowires 50–100 nm in diameter grown by the sol–gel technique were incorporated in the PAni to prepare PAni/MgB₂ nanocomposites, which yielded an enhancement of conductivity by 5 orders of magnitude. PAni was synthesized through the chemical oxidative polymerization method. The composition of the prepared nanocomposites was tunable, i.e. the amount of dopant was varied and the effects on various parameters were observed by different techniques. The morphology of PAni/MgB₂ nanocomposites was determined using SEM. The temperature dependence of the conductivity of all composites was measured in the temperature range 300–450 K and it was observed that samples having a high concentration of MgB₂ show the highest conductivity. The molecular structure of the nanocomposites was further characterized by Fourier Transform IR spectroscopy which showed small structural changes in the backbone of PAni. I?V measurements showed that the current increases on increasing MgB₂ content. UV?visible spectra exposed the occurrence of an indirect optical transition in the composite. © 2013 Society of Chemical Industry     

Synthesis of Triazole-Based Nonionic Surfactants for Nanostructured Drug Delivery: Investigation of Their Physicochemical and Biological Aspects

Synthesis of novel nonionic surfactants has attracted attention of synthetic chemists due to the issues of the currently used commercial surfactants. The synthesis of three biocompatible triazole-based nonionic surfactants is reported for nanovesicular drug loading. The surfactants were synthesized in a three-step reaction and characterized using ¹HNMR and mass spectroscopy techniques. They were investigated for their critical micelle concentration (CMC) using a UV–Visible spectrophotometer. Their biocompatibility was investigated against cell culture and in blood. All the synthesized nonionic surfactants were further explored for their nanovesicular drug loading using clarithromycin as a model hydrophobic drug. Nonionic surfactants revealed lower CMC in 35–45 μM and were less hemolytic and cytotoxic. They were capable of self-assembling in nanosize niosomal vesicles encapsulating increased amounts of drug. The results suggest the synthesized nonionic surfactants as biocompatible nanotechnology-based drug-delivery vehicles.     

Strand Current Distribution Modeling in Turbo-generators Using Finite-element Method Based on Proposed Dual Method

Abstract—The necessity of using a 3D model is one of the main problems for modeling Roebel bar transposition in turbo-generators by the finite-element method. This article proposes a 2D dual model for computing strand current distribution in the Roebel bar of turbo-generators. Considering the leakage and mutual inductances for each strand and the coupling inductances between them, the end winding region is modeled in this 2D dual model. In this article, the Roebel bar structure including 16 strands was considered, and these distributions are calculated for different transpositions using the finite-element method. In the finite-element method model, the circulating currents are calculated by subtracting a load current at each strand from the total of strand current. Also, for different transpositions, such as 90°, 180°, 360°, and 540°, the circulating currents are calculated using an analytical method. The obtained strand current distributions from the 2D dual model have good agreement with the obtained results from the analytical method for the 180° and 360° transposed coil models.     

Improved Feature Extraction by use of a Joint Wavelet Transform Correlator

A new joint wavelet transform correlation-based technique is proposed for feature extraction such as the detection of edges in an unknown input scene. We exploited a modified version of the Roberts and the Sobel wavelet filters as reference images for extracting the edges of an unknown input scene. The performance of the proposed technique with the aforementioned wavelet filters is evaluated and compared by use of numerical simulations. For noise-free input scenes the Roberts wavelet filter was found to yield a superior output compared with that of the Sobel wavelet filter. However, for noisy input scenes the Sobel wavelet filter was found to yield a better output compared with the Roberts wavelet filter.