Molecular simulation for thermoelectric properties of c-axis oriented hexagonal GeSbTe model clusters

Vora-ud, A.,Rittiruam, M.,Kumar, M.,Han, J.G.,Seetawan, T. Elsevier Ltd 2016 Materials & Design Vol.89 No.-

<P>Using a combination of molecular orbital and molecular dynamics simulations, electronic and thermoelectric properties of GeSbTe model clusters are presented. The unit cells of Ge13Sb20Te52, Ge7Sb12Te40 and Ge14Sb6Te26 model clusters are designed corresponding to GeSb2Te4, GeSb4Te7 and Ge2Sb2Te5 compositions in hexagonal phase, oriented in the c-axis direction. The electronic structures of clusters have been simulated by discrete-variational molecular orbital calculation using Hartree-Fock-Slater approximation to determine the electrical conductivity and Seebeck coefficients in Mott expression. For thermal properties, molecular dynamics simulations have been employed on clusters in amorphous, cubic and hexagonal phases using Verlet's algorithm and subsequently using Green-Kubo relation for lattice thermal conductivity. We assumed inter-atomic interaction, defined by the Morse-type potential function added to Busing-Ida potential function, which considers partial electronic charges on the ions, bond length of the cation-anion pair, and depth and shape of the potential. Based on our simulations, detailed variation of electrical conductivity, carrier thermal conductivity, lattice thermal conductivity, Seebeck coefficients, power factor and figure of merit, are presented as a function of temperature in 300-700 K range. Thermoelectric parameters obtained in present study were compared and explained with those of experimentally results of Ge2Sb2Te5 composition in hexagonal phase. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Microstructural control by substrate heating in Pulse-DC sputtering induced thermoelectric Ge₂Sb₂Te₅ thin films

Vora-ud, Athorn,Kumar, Manish,Jin, Su bong,Muthitamongkol, Pennapa,Horprathum, Mati,Thaowonkaew, Somporn,Chao-moo, Watchara,Thanachayanont, Chancana,Thang, Phan Bach,Seetawan, Tosawat,Han, Jeon Geon Elsevier 2018 Journal of alloys and compounds Vol.763 No.-

<P><B>Abstract</B></P> <P>Optimization of substrate heating during sputtering processes is essential to obtain desired microstructures of deposited thin films, as it provides the required energy flux during the nucleation and growth. In this work, Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> thin films were prepared by a pulsed-DC magnetron sputtering process at optimized plasma conditions (pulsed frequency and pulse reversal time). The effect of substrate heating, in temperature range of 250–450 °C, was systematically investigated on the process throughput and various properties i.e. microstructure, morphology, atomic composition, carrier concentration, mobility and Seebeck coefficient of deposited films. The substrate heating was found to be required to obtain films in cubic crystalline phase. Through the optimization of substrate temperature, process throughput and surface properties, electrical properties as well as thermoelectric power factors were enhanced. The maximum power factor value of thin films was achieved as 0.77 mW m<SUP>–1</SUP> K<SUP>–2</SUP> for the substrate temperature as 400 °C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> thin films were successfully microstructural controlled by substrate heating. </LI> <LI> Microstructural of Ge<SUB>2</SUB>Sb<SUB>2</SUB>Te<SUB>5</SUB> thin films were controlled for thermoelectric properties. </LI> <LI> Thermoelectric properties were discussed based on temperature of substrate heating. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Parametric study of shear capacity of beams having GFRP reinforcement

Vora, Tarak P.,Shah, Bharat J. Techno-Press 2022 Advances in concrete construction Vol.13 No.2

A wide range of experimental bases and improved performance with different forms of Fiber Reinforced Polymer (FRP) have attracted researchers to produce eco-friendly and sustainable structures. The reinforced concrete (RC) beam's shear capacity has remained a complex phenomenon because of various parameters affecting. Design recommendations for the shear capacity of RC elements having FRP reinforcement need a more experimental database to improve design recommendations because almost all the recommendations replace different parameters with FRP's. Steel and FRP are fundamentally different materials. One is ductile and isotropic, whereas the other is brittle and orthotropic. This paper presents experimental results of the investigation on the beams with glass fiber reinforced polymer (GFRP) reinforcement as longitudinal bars and stirrups. Total twelve beams with GFRP reinforcement were prepared and tested. The cross-section of the beams was rectangular of size 230 × 300 mm, and the total length was 2000 mm with a span of 1800 mm. The beams are designed for simply-supported conditions with the two-point load as per specified load positions for different beams. Flexural reinforcement provided is for the balanced conditions as the beams were supposed to test for shear. Two main variables, such as shear span and spacing of stirrups, were incorporated. The beams were designed as per American Concrete Institute (ACI) ACI 440.1R-15. Relation of VExp./VPred. is derived with axial stiffness, span to depth ratio, and stirrups spacing, from which it is observed that current design provisions provide overestimation, particularly at lower stirrups spacing.

Risk based approach for design and optimization of site specific delivery of isoniazid

Chintan Vora,Riddhish Patadia,Karan Mittal,Rajashree Mashru 한국약제학회 2015 Journal of Pharmaceutical Investigation Vol.45 No.2

The research envisaged focuses on risk managementapproach for development and optimization ofenteric coated tablet of isoniazid giving extended release inpH 6.8 phosphate buffer. Risk assessment using failure modeand effects analysis was done to depict the effects ofunambiguous failure modes related to particular formulation/process variable. A 2³ full factorial design wasemployed for optimization of core tablet to investigate effectof amount of Polyox WSR303 (A), hardness (B) and amountof ethyl cellulose (C) on percent drug release in pH 6.8phosphate buffer. Main effects and interaction plots weregenerated to study effects of variables. The selection ofoptimized formulation was done on overlay contour plotsand desirability function. The optimized formulationexhibited percent drug release at first hour of 26.97 %, secondhour of 44.20 %, fourth hour of 66.15 %and eighth hourof 97.9 % in phosphate buffer pH 6.8. Akaike informationcriteria and Model selection criteria revealed that the modelwas best described by Korsmeyer–Peppas power law. TheKopcha and Peppas–Sahlin model revealed diffusion aspredominant mechanism of release which may be due to highsolubility of drug and drug loading. Enteric coating optimizationrevealed weight gain of 10 %w/w as optimum; givingnil release of isoniazid in 0.1 N hydrochloric acid. Thecomposite desirability for optimized formulation computedusing equations and software were 0.91 and 0.90 respectively. Capability analysis on reproducibility batchesrevealed all indices above 1.33 signifying process was withincontrol of producing batches as per desired specifications.

Design and Optimization of Microstructure for Improved Corrosion Resistance in Laser Surface Alloyed Aluminum with Molybdenum

Hitesh D. Vora,Narendra B. Dahotre,Ravi Shanker Rajamure,Santhanakrishnan Soundarapandian,S. G. Srinivasan 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

The in-situ measurement of dilution during the laser surface alloying process is an enormously difficult task, due to the localized nature of laser energy and very short laser-material interaction time. Therefore, a computational approach (finite-element method and analysis of variance) was effectively employed to evaluate the dilution during the laser surface alloying process. Firstly, a finiteelement model based on COMSOL™ multiphysics was developed to predict the dilution of Mo with Al during non-equilibrium laser surface alloying process. Secondly, the optimization model based on Design-Expert® was developed to find the optimal laser surface alloying parameters (laser power, scanning speed, and fill spacing) to obtain a microstructure suitable for improved corrosion resistance that is primarily attributed to the formation of Al5Mo intermetallic phase (16.7 at% Mo). The present optimization model utilized the prior experimental and computational (finite-element) modeling data for the concentration of Mo (at%). The optimization analyses were carried out for the all the current datasets and the analysis revealed 44 optimal solutions that indicate the highest desirability. The confirmation runs were carried out to validate the optimization model. The experimental observation showed that the sample processed with optimal processing conditions demonstrates good corrosion resistance.

Experimental investigation on shear capacity of RC beams with GFRP rebar & stirrups

Tarak P. Vora,Bharat J. Shah 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.6

This paper presents experimental results of advanced investigation carried out on the beams reinforced with Glass Fiber Reinforced Polymer (GFRP) rebar and stirrups. Twelve beams reinforced with GFRP and one beam with steel reinforcement of size 230 × 300 × 2000 mm were investigated. Longitudinal reinforcement, shear span and spacing of stirrups were the main variables to form the set. In advanced testing three types of strain gauges for steel, composite and concrete surface were applied to observe strain/stress development against the applied load. Live data were recorded from four strain gauges applied on stirrups, one at center on longitudinal reinforcement, two on the concrete surface and central deflection during the test. Although the focus of the paper was mainly on the behavior of GFRP shear reinforcement, other parallel data were observed for the completeness of the test. Design recommendations of ISIS Canada Design Manual (2007), Japan Society of Civil Engineers (1997) and American Concrete Institute (ACI-440.1R-06) were reviewed. Shear design predictions were compared with experimental results in which it was observed that all the three standards provided conservative predictions. However, ACI found most efficient compare to other two there is room to improve the efficiency of the recommendations.

Study of pulsed-DC sputtering induced Ge₂Sb₂Te₅ thin films using facile thermoelectric measurement

Kumar, M.,Vora-ud, A.,Seetawan, T.,Han, J.G. Elsevier Ltd 2016 Materials & Design Vol.98 No.-

<P>Thermoelectric measurement is an exhaustive exercise for the case of thin films, requiring meticulous attention to the thermal contact interfaces and the instrumentation. Usually, different set-ups are combined for the temperature dependent measurement of different thermoelectric key quantities. Here, a facile 6-probe measurement set-up is presented, which can measure Seebeck coefficients and electrical properties of thin films in the temperature range of 300 K-600 K. Using this set-up, the thermoelectric properties of Ge2Sb5Te5 thin films, prepared with pulsed DC magnetron sputtering method are studied. The effects of working pressure, post-deposition thermal treatment and variation of film thickness on the microstructure, surface, electrical and thermoelectric properties are investigated systematically. Plasma diagnostics, performed using optical emission spectroscopy provided the information about various radicals' excitations and the electron temperature. Microstnictural studies show the phase transformation from amorphous to metastable cubic phase. FESEM study exhibits highly dense films with uniform grains compactness. It has been found that lowering average crystallite size by optimum electron temperature and pressure conditions governs the enhancement in Seebeck coefficient. The throughput of process >400 nm/min, and obtained Seebeck coefficients values 271.50 mu V/K are highly promising for industrial utilization. (C) 2016 Elsevier Ltd. All lights reserved.</P>

From Financial Literacy to Financial Capability: A Preliminary Study of Difference Generations in Informal Labor Market

AMONHAEMANON, Dalina,VORA-SITTA, Pornpen Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.12

This study aims to investigate whether financial attitude links financial literacy to financial capability. To make sound financial decisions, one essentially requires a certain level of financial literacy - knowledge and skill in finance. Even more effective is when one's financial literacy could be developed into financial capability. The samples comprised 342 individuals from informal labor in the South of Thailand. The stratified multistage sampling technique was utilized to select the respondents, while the interview questionnaires were used to collect the data. By using SmartPLS 3.0, the data analysis included descriptive statistics and structural equation modeling (SEM). The result revealed that the one with the highest debt was Gen Y compared to Gen B and Gen X. Considering financial literacy, financial attitude, and financial capacity across generations, it was found that Gen Y had the highest average score in financial literacy and financial capacity, higher than that of Gen X and Gen B. The impact of financial literacy on financial capability through financial attitude, it was found that the impact on Gen B was higher than that of Gen X and Gen Y. With the right financial attitude, people of all generations would be equipped with a higher level of financial capability.

The Role of Economic Cluster Perspectives in Regional Economic Development

Haak, Robert,Vora, Gautam,Walsh, Steven T.,White, Craig G. World Technopolis Association 2014 World Technopolis Review Vol.3 No.1

The importance of science and technology as the root of exceptional regional economic development has been extolled since the time of Schumpeter. Today emerging technologies are signaling the start of a new economic cycle where regions that are effective in technology translation will gain advantage. The will of policymakers to translate technology into regional job and wealth creation seems to be at an all-time high. Yet an improved process for translating technical development into regional prosperity has proved elusive. If there are no processes other than applying techniques that have worked in the past for other regions to a new region then there is cause for concern. Here the authors seek to add to this field of knowledge by applying elements of the varied cluster theories to provide a basis for policy for regional economic development by turning science and technology into commercial innovation. We provide a review of current cluster theories and discuss the positive and negative issues associated with each. We propose a model that allows interested professionals to utilize aspects of each cluster perspective geared to the realities of their specific area.

Removal of pollutants from wastewater using alumina based nanomaterials: A review

Mahesh Ramakrishna,Vora Khushi,Hanumanthaiah Madhu,Shroff Anuradha,Kulkarni Pavan,Makuteswaran Sridharan,Ramdas Suresh,Ramachandraih Hemanth Lakshmipura,Raghu Anjanapura Venkatarmanaiah 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9

Increasing urbanization and industrialization has led to a dramatic increase in demand for clean potable water. Nanotechnology is used in environmental applications to eliminate pollutants, pathogens, and other effluents from water. Nanomaterials have gained importance in sustainable development. Alumina (Al2O3) and its composites are generally used as nanomaterials because of high surface area, porous nature, large number of active sites, formation of meta-stable phase and hexagonal structure, which makes it a potential candidate for water treatment. The nano alumina can be coated on membranes and the composites can be used for purification of water, specifically for the removal of heavy metal ions, dyes and other microbes. The prime focus of the review paper is the treatment of water using alumina composites; the same can be extended to other applications like dye removal and desalination with some modifications.