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Ligand mediated eco-friendly leaching of zinc from spent catalyst in alkaline media
M. Mohapatra,Banaja Nayak,K. Sanjay,T. Subbaiah,B.K. Mishra 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
A novel leaching process for recovering Zn from spent catalyst in alkaline solution has been discussed. The catalyst was characterized for physico-chemical properties by chemical, XRD, TG-DTA and SEM. More than 92% Zn could be extracted from spent catalyst under the conditions: pulp density 2.5% (w/v), NaOH 1 M, EDTA 0.025 M, temperature 80℃ and time 3 h. Zn extraction increased with the number of stages. At the 4th stage almost all Zn could be extracted. A tentative process flow-sheet has been proposed based on Zn recovery. Characterization of leach residue by XRD and SEM gave an insight into the mechanism.
Electronic nutritional intake assessment in patients with urolithiasis: A decision impact analysis
Avory M. Heningburg,Anand Mohapatra,Aaron M. Potretzke,Alyssa Park,Alethea G. Paradis,Joel Vetter,Adrienne N. Kuxhausen,Leslie D. McIntosh,Anthony Juehne,Alana C. Desai,Gerald L. Andriole,Brian M. Ben 대한비뇨의학회 2016 Investigative and Clinical Urology Vol.57 No.3
Purpose: To evaluate a physician's impression of a urinary stone patient's dietary intake and whether it was dependent on the medium through which the nutritional data were obtained. Furthermore, we sought to determine if using an electronic food frequency questionnaire (FFQ) impacted dietary recommendations for these patients. Materials and Methods: Seventy-six patients attended the Stone Clinic over a period of 6 weeks. Seventy-five gave consent for enrollment in our study. Patients completed an office-based interview with a fellowship-trained endourologist, and a FFQ administered on an iPad. The FFQ assessed intake of various dietary components related to stone development, such as oxalate and calcium. The urologists were blinded to the identity of patients' FFQ results. Based on the office-based interview and the FFQ results, the urologists provided separate assessments of the impact of nutrition and hydration on the patient's stone disease (nutrition impact score and hydration impact score, respectively) and treatment recommendations. Multivariate logistic regressions were used to compare pre-FFQ data to post-FFQ data. Results: Higher FFQ scores for sodium (odds ratio [OR], 1.02; p=0.02) and fluids (OR, 1.03, p=0.04) were associated with a higher nutritional impact score. None of the FFQ parameters impacted hydration impact score. A higher FFQ score for oxalate (OR, 1.07; p=0.02) was associated with the addition of at least one treatment recommendation. Conclusions: Information derived from a FFQ can yield a significant impact on a physician's assessment of stone risks and decision for management of stone disease.
Pathak, M.S.,Gopal, N.O.,Singh, N.,Mohapatra, M.,Rao, J.L.,Lee, Jung-Kul,Singh, Vijay Elsevier 2018 Journal of non-crystalline solids Vol.500 No.-
<P><B>Abstract</B></P> <P>Iron doped lithium metasilicate sample was synthesized using a combustion technique and characterized by XRD (X ray diffraction), SEM (scanning electron microscopy), FTIR (Fourier transform infrared spectroscopy), optical, and EPR (electron paramagnetic resonance) analyses. The phase purity of the combustion synthesized products was confirmed by XRD analysis. SEM data suggested the formation of a porous compound by virtue of the entrapment of the gases that evolved during the sample synthesis. FTIR data confirmed the formation of SiO bonds in the system. Optical data confirmed the existence of both divalent and trivalent iron in the system. Characteristic absorption bands in the region 215–270 nm and 535–620 nm were observed due to the presence of Fe<SUP>3+</SUP> in Oh and Td geometry respectively. On the other hand, the presence of bands at 967 and 1442 nm suggested the stabilisation of Fe<SUP>2+</SUP> also in both Oh and Td geometries, respectively. The divalent iron being a non-Kramer ion, could not be observed by EPR. However, strong temperature-dependent EPR signals were observed in the sample owing to Fe<SUP>3+</SUP>. By analyzing the EPR data, super-paramagnetic type of behaviour was observed in the system. Furthermore, the relaxation times along with other EPR spectroscopic parameters were estimated for the system.</P>
Effect of Cr-Rich Phase Precipitation on Magnetic and Mechanical Properties of Fe-20% Cr Alloy
Mohapatra, J. N.,Kamada, Y.,Kikuchi, H.,Kobayashi, S.,Echigoya, J.,Park, D. G.,Cheong, Y. M. IEEE 2011 IEEE transactions on magnetics Vol.47 No.10
<P>Magnetic Hysteresis Loop (MHL) and micro-Vickers hardness measurements were carried out in isothermal aged Fe-20 wt. % Cr alloy. The results were compared with the existing atom probe data at similar heat treated conditions. Coercivity and hardness of the alloy was increased and remanence of the alloy was decreased with the increase in ageing time. Such increase in the magnetic and mechanical hardness was due to the nucleation and growth of Cr rich α' phase. The size of the Cr rich α' phase precipitates were increased and the number density of the precipitates were decreased with the increase in ageing time observed by atom probe analysis. In this work a good correlation between hardness (H<SUB>v</SUB>) and coercivity (H<SUB>c</SUB>) was found with the combined effect of precipitate size (r) and number density (n). A linear relationship was found with the change in coercivity and hardness of the alloy indicating that the MHL technique would be a good Non-Destructive Evaluation (NDE) tool for the evaluation of thermal embrittlement in structural components made of Fe-Cr alloys.</P>
Evaluation of Embrittlement in Isochronal Aged Fe-Cr Alloys by Magnetic Hysteresis Loop Technique
J. N. Mohapatra,Y. Kamada,H. Kikuchi,S. Kobayashi,J. Echigoya,D. G. Park,Y. M. Cheong 한국자기학회 2011 Journal of Magnetics Vol.16 No.2
Fe-Cr alloys with different Cr contents were prepared by an arc melting technique. The alloys were isochronally aged in the range from 400 ℃ to 900 ℃ with 50 ℃ steps with a holding time of 100 hours. The ageing produced embrittlement in the alloys due to either the formation of a Cr-rich α’ phase or a σ phase at high temperatures. Magnetic Hysteresis Loop (MHL) and Micro-Vickers hardness were measured at each step to correlate the magnetic and mechanical properties. Coercivity and hardness of the alloys were increased and remanence decreased up to 500-550 ℃ due to formation of a Cr-rich α’ phase. Beyond 500-550 ℃ range, the coercivity and hardness decreased and remanence increased due to the coarsening or dissolution of the Cr-rich α’ phase. In the Fe-48% Cr alloy, formation of the σ phase at 700 ℃ reduced the maximum induction of the alloy significantly.
Singh, V.,Mohapatra, M.,Sivaramaiah, G.,Rao, J. L.,Singh, N.,Gao, H.,Li, J.,Srivastava, A. K.,Jirimali, H. D.,Dhoble, S. J. Springer Science + Business Media 2016 Journal of materials science Materials in electron Vol.27 No.4
<P>Manganese doped BaMgAl10O17 nano-phosphors were synthesized by a low-temperature initiated, gas producing solution combustion process. Phase purity of the prepared phosphors was determined using X-ray diffraction technique. Dynamic light scattering technique was used to estimate the average particle size of the synthesized products. Scanning electron microscopy technique was used to study the morphology of the prepared samples. Fourier transform infrared spectroscopy was used to ascertain the formation of the aluminate host. UV-visible absorption spectroscopy showed band maxima at around 260 nm and intense band maxima at around 216 nm. Electron paramagnetic resonance experiments for the system were carried out to understand the site occupancy of the Mn ions. The photoluminescence excitation and emission spectra suggested the stabilisation of Mn ions in Td geometry. From the colour characterisation of the system it was found out that the system can be effective as a green phosphor material with wide range of applications.</P>
Singh, V.,Sivaramaiah, G.,Mohapatra, M.,Rao, J. L.,Singh, N.,Pathak, M. S.,Singh, P. K.,Dhoble, S. J. Springer Science + Business Media 2017 Journal of Electronic Materials Vol.46 No.2
<P>GdAlO3 phosphor samples have been prepared by a solution combustion method. X-ray diffraction analysis revealed that the GdAlO3 phosphor stabilized in orthorhombic phase. The optical absorption spectrum showed bands due to Gd3+ ions as well as defect level in the host. The excitation spectrum exhibited a dominant band with maximum at 273 nm. Upon excitation at 273 nm, ultraviolet-B (UV-B) emission with maximum at 312 nm was observed from the undoped sample, being attributed to P-6(7/2) -> S-8(7/2) transition of Gd3+ ion. The UV-B emission was enhanced at liquid-nitrogen temperature (77 K), most probably due to increased ground-state population according to the Boltzmann distribution law. Electron spin resonance spectra of samples at both room and liquid-nitrogen temperature exhibited resonance signals at g ae 2, attributed to Gd3+ ions arranged with octahedral symmetry linked via oxygen bridges. Various magnetic and thermodynamic parameters for the phosphor system were evaluated by standard procedures. Correlation of these values with the optical properties suggested that the GdAlO3 phosphor can be effectively used as an UV-B light source for industrial applications at room temperature.</P>
Carbon nanoflake growth from carbon nanotubes by hot filament chemical vapor deposition
Sahoo, S.C.,Mohapatra, D.R.,Lee, H.J.,Jejurikar, S.M.,Kim, I.,Lee, S.C.,Park, J.K.,Baik, Y.J.,Lee, W.S. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.67 No.-
We report the growth of carbon nanoflakes (CNFs) on Si substrate by the hot filament chemical vapor deposition without the substrate bias or the catalyst. CNFs were grown using the single wall carbon nanotubes and the multiwall carbon nanotubes as the nucleation center, in the Ar-rich CH<SUB>4</SUB>-H<SUB>2</SUB>-Ar precursor gas mixture with 1% CH<SUB>4</SUB>, at the chamber pressure and the substrate temperature of 7.5Torr and 840<SUP>o</SUP>C, respectively. In the H<SUB>2</SUB>-rich condition, CNF synthesis failed due to severe etch-removal of carbon nanotubes (CNTs) while it was successful at the optimized Ar-rich condition. Other forms of carbon such as nano-diamond or mesoporous carbon failed to serve as the nucleation centers for the CNF growth. We proposed a mechanism of the CNF synthesis from the CNTs, which involved the initial unzipping of CNTs by atomic hydrogen and subsequent nucleation and growth of CNFs from the unzipped portion of the graphene layers.