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Hydrogen production from water-splitting reaction based on RE-doped ceria-zirconia solid-solutions
Dasari, H.P.,Ahn, K.,Park, S.Y.,Ji, H.I.,Yoon, K.J.,Kim, B.K.,Je, H.J.,Lee, H.W.,Lee, J.H. Pergamon Press ; Elsevier Science Ltd 2013 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.38 No.14
The effect of rare earth (RE = Tb, Pr and La) dopant on the catalytic performance of RE-doped ceria-zirconia (CZRE) solid-solutions for oxygen storage capacity and hydrogen production activity has been successfully investigated. The sustainability of the solid-solutions even after the reduction was confirmed by XRD. Raman analysis showed that the addition of RE element in CZ system significantly decreased the intensity of the characteristic fluorite peak (462-474 cm<SUP>-1</SUP>) indicating a highly deformed structure than CZ system which can enhance the oxygen mobility and redox property of these materials and the order of the intensity decrease was Pr > Tb > La. The XPS measurements revealed that the CZPr sample has a homogeneous distribution of Ce/Zr and also showed a high enrichment of Pr on the particle surface than the others. Among the CZRE solid-solution catalysts tested, CZPr catalyst showed the best catalytic performance for high OSC and hydrogen production from water-splitting reaction.
Record-low sintering-temperature (600 <sup>o</sup>C) of solid-oxide fuel cell electrolyte
Dasari, H.P.,Ahn, K.,Park, S.Y.,Hong, J.,Kim, H.,Yoon, K.J.,Son, J.W.,Kim, B.K.,Lee, H.W.,Lee, J.H. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.672 No.-
One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 <SUP>o</SUP>C) to fully densify the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 <SUP>o</SUP>C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 <SUP>o</SUP>C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (~150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ~1.00 x 10<SUP>-2</SUP> S cm<SUP>-1</SUP> at 600 <SUP>o</SUP>C in air and from the conductivity plots the activation energy is found to be 0.53 eV.
Dasari Rekha,Jengiti. Dilip Kumar,Bellum Jayaraj,Y. Lingappa,Pattium Chiranjeevi* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.3
A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (lmax 497 nm) at pH 4.0 0.2. Beers law was obeyed over the range of 0.01-0.1 g L-1. The molar absorptivity and Sandells sensitivity were 1.285 105 L mol-1cm-1 and 0.007245 g cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 g L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Students t-test and Variance ratio f-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.
Rekha, Dasari,Kumar, Jengiti. Dilip,Jayaraj, Bellum,Lingappa, Y.,Chiranjeevi, Pattium Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.3
A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.
S. K. Dasari,S. Ganguly,A. Abutunis,K. Chandrashekhara,M. F. Buchely,S. N. Lekakh,R. J. O’Malley,T. Natarajan 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
Microstructural changes and softening due to static recrystallization have a critical influence on thermo-mechanical behaviorof high strength steels during industrial multi-pass hot rolling. Numerical simulation using finite element analysis (FEA)can be used to accurately predict the softening behavior during the hot rolling process. Therefore, the implementation of anexperimentally defined static recrystallization model into FEA is necessary to get realistic simulation prediction. In this study,the extent of softening during static recrystallization in Si and Mn alloyed high strength steel was measured using doublehit tests. A Gleeble™ thermo-mechanical simulator was used to perform the double hit tests with variations in temperature,strain rate, and interpass time. The kinetics of static recrystallization was developed based on the experimental results andimplemented into a finite element model of a multi-pass plate hot rolling process using explicit subroutines. Three differentmodeling approaches were implemented in Abaqus to predict the fraction of static recrystallization and softening duringmulti-pass hot rolling. Simulation results showed that the fraction of recrystallization significantly depends on the extent ofthickness reduction during rolling at a typical industrial multi-pass schedule. Additionally, an increase in temperature greatlyincreased the fraction of recrystallization and static softening. The suggested approach could be used for the optimizationof the hot rolling process for Si and Mn alloyed high strength steels.
Kishore B. Dasari,조하나,Radojko Ja cimovi c,박병건,선광민 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.2
The selection and effective utilization of peak-fitting software for conventional gamma-ray spectrumanalysis is significant for accurate determination of the mass fraction of elements, particularly in complexpeak regions. Majority of the peak-fitting programs can derive similar peak characteristics for singletpeaks, but very few programs can deconvolute multi-peaks in a complex region. The deconvolution ofmulti-peaks requires special peak-fitting functions, such as left and right-skew distributions. In the thisstudy, 843.76 keV (27Mg) peak area from the complex region (840 keVe850 keV) determined andcompared using four different peak-fitting programs, namely, GammaVision, Genie2000, HyperLab, andHyperGam. The 843.76 keV peak interfered with 841.63 keV (152mEu) and 846.81 keV (56Mn). The totalMg concentration was determined through k0-instrumental neutron activation analysis by applying theisotopic interference correction factor 27Al(n,p)27Mg through the simultaneous determination of Alconcentration. HyperLab and HyperGam peak-fitting programs reported consistent peak areas, andresultant concentrations agreed with the certified values of matrix-certified reference materials.