An electrochemical technique to deposit thin films of PbTe

PbTe thin films were deposited electrochemically on transparent conducting oxide coated (TCO) glass substrates from a solution of lead acetate and TeO₂ at low pH. A lead (Pb) strip was used as a sacrificing anode and the TCO glass acted as the cathode, which were short-circuited externally. Depositions were carried out at different temperatures of the bath to study the growth kinetics and grain growth. X-ray diffraction technique, scanning electron microscopy, infrared spectroscopy and resistivity measurements were carried out to characterize the deposited films. The films were polycrystalline in nature with a cubic phase.     

Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.     

Pipelined VLSI Architecture using CORDIC for Transform Domain Equalizer

In this paper, a pipelined architecture using CORDIC for realization of transform domain equalizer is presented. Transform domain equalizer has much faster convergence than its time domain counterpart for practical hardware realization having nonzero adaptation delay. Here running DFT is employed as the transform, and CORDIC is used for realization of running DFT. Pipelining is applied throughout the architecture, thus limiting the critical path delay to the propagation delay of a single 16 bit adder for 16 bit arithmetic. For N tap equalizer, primary clock speed is N times of the sample clock speed, so that on arrival of each sample, the computation of whole transform and weight update is possible. In the proposed architecture, hardware complexity is reduced by fully utilizing the pipeline without using parallel structures. The adaptation delay is only 2 sample clock periods resulting in fast convergence. The proposed architecture is suitable for VLSI implementation with primary clock speed limited by the binary adder propagation delay which could be as low as 2 ns in the present state-of-the-art technology.     

Integrated Computational Materials Engineering (ICME) Approach to Design of Novel Microstructures for Ti-Alloys

In this overview, we present integrated CAPHAD and phase-field modeling with critical experiments to explore a newly discovered, nonconventional, solid–solid phase transformation pathway based on the so-called pseudo-spinodal mechanism. We show that this new transformation pathway offers a new design strategy for Ti alloys with extremely fine and uniform α + β microstructures that could potentially have highly attractive balances of mechanical properties. To broaden the processing window for such a mechanism to operate, we also explore a different nonconventional transformation pathway that involves precursory phase separation. In addition, the variant selection process during the β → α transformation leading to macrozones is investigated and the results could shed light on how to control processing conditions to avoid or reduce microtexture at both the individual β grain level and the overall polycrystalline sample level.     

Effect of the surface roughness of conducting polypyrrole thin-film electrodes on the electrocatalytic reduction of nitrobenzene

Conducting polypyrrole (PPy) thin-film electrodes were prepared by the electropolymerization of pyrrole on gold-coated glass plates. Films of various roughnesses were obtained by the variation of the scan rates during electropolymerization. These thin films were modified by doping with 6mM of the dopant NiCl₂. The surface morphology of the films was studied by scanning electron microscopy and atomic force microscopy (AFM), which suggested films prepared with a high scan rate were rougher in nature than the films produced with a low scan rate. The electrocatalytic reduction of nitrobenzene was carried out with these electrodes with the cyclic voltammetry technique in acetonitrile containing 0.1M HClO₄ as a supporting electrolyte. The various results obtained show that the conducting PPy thin-film electrodes were catalytically active toward the electroreduction process. The modified PPy film electrodes doped with NiCl₂ were more active toward nitrobenzene electroreduction than the PPy film alone. The results indicate that the roughness of the films played a very important role in determining their catalytic activity. The PPy films that were more rough in nature were catalytically more active than the smooth films; this may have been due to the availability of more reactive sites in the case of rough films. The apparent diffusion coefficients of the PPy film electrodes were also calculated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

On the Role of C Addition on α Precipitation in a β Titanium Alloy

The onset of α nucleation in a carbon containing β-titanium alloy has been investigated by coupling atom probe tomography (APT) with transmission electron microscopy. The analysis of the APT results indicates that in addition to ω precipitates that can act as potential α nucleation sites, carbon atoms tend to form clusters within the β-matrix, which in turn give rise to additional nucleation sites for α, resulting in finer scale α precipitates due to increased nucleation density.     

Effect of NOx on AgI formation in Ag-mordenite

Ag loaded mordenite can be used as a trap for radio-iodine arising from nuclear reprocessing operations. Typically, iodine is trapped in the Ag loaded mordenite by the formation of AgI in the pores of the mordenite, through a solid-vapour reaction. In the presence of NO_x and water vapour, AgI is most likely formed by liquid-vapour reaction between AgNO₃ and I₂. This reaction results in the formation of large aggregates of AgI crystals on the surface of the mordenite, also leading to a yellow colouration of the mordenite, which is not observed when NO_x and water vapour is absent.     

A simple and efficient sun tracking mechanism using programmable logic controller

To increase the unit area illumination of solar ray on PV panel, it is required to track the sun throughout the day. So to reach the goal various type of sun tracking mechanism is already developed but in this paper we designed two different types of sun tracking mechanism: single axis and dual axis tracking using programmable logic controller (PLC) as it has numbers of unique advantages like??it is faster, reliable, requires less maintenance and reprogrammable. A comparative study between those two systems is also presented in this paper. The whole system has been designed and tested using GE, FANUC PLC.     

Alginate–chitosan composite hydrogel film with macrovoids in the inner layer for biomedical applications

Making of a layered composite using two biopolymer gels with regularly aligned voids in the inner layer is described in this article. Calcium alginate constituted the inner layer, within which voids of 500 μm diameter were embedded in monolayer or in multiple layers using a fluidic device for bubbling. The chitosan without any additional crosslinker was used to form the outer layer. The layered structure enabled compartmentalization of drug hold-up, and differential release rates. These aspects were reviewed using bovine serum albumin and vitamin B₁₂ as model solutes. The presence of voids at the inner layer of alginate increased the uptake, raising the level of absorptivity to more than 4000%. The composite film could hold two solutes at a time. The one, held inside the alginate layer started releasing only after 1 h of dipping in the release media. The adhesive strength between layers and the response of the composite film to compressive deformation are studied here. The effect of single or multiple layers of voids in the inner layer is reviewed. The slowing of degradation rate due to chitosan-encapsulation is experimentally determined. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47599.