Papers by 255 VIKASH MISHRA
Solid State Communications, 2016
Theoretical Raman line shape functions have been studied to take care of quantum confinement effe... more Theoretical Raman line shape functions have been studied to take care of quantum confinement effect and Fano effect individually and jointly. The characteristics of various Raman line shapes have been studied in terms of the broadening and asymmetry of Raman line shapes. It is shown that the asymmetry in the Raman line-shape function caused by these two effects individually does not add linearly to give asymmetry of lineshape generated by considering the combined effect. This indicates existence of interplay between the two effects. The origin of interplay lies in the fact that Fano effect itself depends on quantum confinement effect and in turn provides an asymmetry. This can not be explained by considering the two effects contribution independent of each other.
Indian Journal of Transplantation, 2022
Background: Timeline is a key factor for hematopoietic stem cell transplant (HSCT) recipient. HSC... more Background: Timeline is a key factor for hematopoietic stem cell transplant (HSCT) recipient. HSCT by matched unrelated donor (MUD) is a standard definitive therapeutic approach for many hematological disorders which are not amenable to chemotherapy and other conventional treatment. Aims and Objectives: The aim of the present study was to compare the turnaround time (TAT) involved in completion of MUD HSCT workup from an Indian registry (Genebandhu) with international registries. Materials and Methods: On receipt of pre-transplant matching request through a transplant physician, patient's human leukocyte antigen (HLA) type was entered in both Genebandhu and World Marrow Donor Association search tool for initiating a “search.” The software gave the descending order of the best possible matches by performing computational analysis. The search result was considered a “match” when potential 10/10 HLA match was found. The average TAT was calculated in the middle of search request and...
SSRN Electronic Journal, 2021
SSRN Electronic Journal, 2021
We report the realization of near-white light emission (near-WLE) and the selective tuning to the... more We report the realization of near-white light emission (near-WLE) and the selective tuning to the near-infrared (NIR) luminescence from Ga substituted lanthanum chromite perovskite with electron-beam excitation. The Ga3+ acts as an electron donor in the LaCrO3 system and the emission intensity increases with Ga substitution. The near-WLE in CL, arises from the combination of 4T1(F)→4A2 (blue), 4T1(P)→4A2 (green) and 4T2→4A2 (red) spin allowed transitions and 2E→4A2 spin forbidden transitions from the Cr3+ ion. The spin allowed transitions from the Cr3+ ions are not common, however can be accomplished by adjusting the Cr3+/Ga3+ ion concentration in the host lattice. The NIR emission originates from the selective 2E→4A2 transition, which dominates with the increasing concentration of Ga3+ ions. The Density Functional Theory (DFT) calculations point out the presence of extra electronic states with Ga substitution, which validates the observation of NIR emission in Ga substituted samples.
The Journal of general virology, Jan 3, 2015
Defective hepatitis B virus (dHBV) particles contain genomes corresponding to singly-spliced HBV ... more Defective hepatitis B virus (dHBV) particles contain genomes corresponding to singly-spliced HBV RNA. A limited number of studies show that dHBV is present in all chronic HBV patients. Clinical studies have linked dHBV and dHBV gene products to high virus loads and liver damage. The replication characteristics of dHBV genomes remain poorly understood. We found that the splice donor/acceptor sites critical for the formation of dHBV genomes are conserved across HBV genotypes. We report a novel method to create dHBV constructs from corresponding wild-type HBV constructs. We assessed the transcriptional characteristics of the dHBV constructs with that of corresponding wild-type construct using a cell culture model. Interestingly, dHBV constructs have higher pgRNA levels, transcription efficiency, HBeAg levels and intracellular HBcAg levels as compared to corresponding wild-type HBV constructs. Our findings highlight previously unrecognized fundamental molecular characteristics of dHBV g...
Alzheimer's & Dementia, 2012
Alzheimer's & Dementia, 2011
Materials Research Express, 2015
The polycrystalline samples of LaGa 1-x Mn x O 3 (0<x<0.3) has been prepared by solid state react... more The polycrystalline samples of LaGa 1-x Mn x O 3 (0<x<0.3) has been prepared by solid state reaction route. The phase purity of these samples has been confirmed by powder x-ray diffraction experiments carried out on BL-12 at Indus-2 synchrotron radiation source. The sample with x=0.2 shows significant change in the value of capacitance with the application of magnetic field. The observed results were understood by systematically analyzing magnetocapacitance (MC), magneto resistance (MR) and dielectric loss as a function of frequency. Our results and analysis suggests that the observed magneto dielectric (MD) coupling may be due to the MR effect of Maxwell-Wagner type and/or field induced dipolar relaxation. Further it is observed that the oxygen stoichiometry plays a very crucial role in observed MD coupling.
arXiv: Strongly Correlated Electrons, Dec 20, 2016
The temperature dependent diffuse reflectance spectroscopy measurements were carried out on the p... more The temperature dependent diffuse reflectance spectroscopy measurements were carried out on the polycrystalline samples of BaTiO 3 across the tetragonal to cubic structural phase transition temperature. The values of various optical parameters such as band gap (E g), Urbach energy (E U) and Urbach focus (E 0) are estimated in the range of 300 K to 470K. It is observed that near structural phase transition temperatures there exists two value of E 0 , suggesting presence of electronic heterogeneity over wide temperature range. Further near transition temperature E U shows metastability i.e. value of E U at temperature T is not constant but is a function of time (t). Interestingly it is observed that the ratio of E U(t=0) / E U(t = tm) , is almost remains constant at 295 K (pure tetragonal phase) and at 450 K (pure cubic phase), whereas this ratio shows decreasing behavior close to structural phase transition temperature, which confirms the presence of electronic metastibility in the pure BaTiO 3. The observed metastibility can be fitted with the stretch exponents relaxation behavior, suggesting the presence of dynamic heterogeneous electronic disorder present in the sample across the transition. Further it appears that these metastable Urbach tail states (electronic disorder) may couple with the soft phonon modes and responsible for the observed terahertz dielectric relaxation (Phys. Rev. Lett. 101, 167402 (2008)). Further; present studies suggest that the optical studies appear to be more sensitive to probe the disorder/heterogeneity present in the sample.
With the growing popularity, the number of data sources and the amount of data has been growing v... more With the growing popularity, the number of data sources and the amount of data has been growing very fast in recent years. The distribution of operational data on disperse data sources impose a challenge on processing user queries. In such database systems, the database relations required by a query to answer may be stored at multiple sites. This leads to an exponential increase in the number of possible equivalent or alternatives of a user query. Though it is not computationally reasonable to explore exhaustively all possible query plans in a large search space, thus a strategy is requisite to produce optimal query plans in distributed database systems. The query plan with most cost-effective option for query processing is measured necessary and must be generated for a given query. This paper attempts to generate such optimal query plans using a parameter less optimization technique Teaching-Learner Based Optimization(TLBO). The TLBO algorithm was experiential to go one better than...
With the growing popularity, the number of data sources and the amount of data has been growing v... more With the growing popularity, the number of data sources and the amount of data has been growing very fast in recent years. The distribution of operational data on disperse data sources impose a challenge on processing user queries. In such database systems, the database relations required by a query to answer may be stored at multiple sites. This leads to an exponential increase in the number of possible equivalent or alternatives of a user query. Though it is not computationally reasonable to explore exhaustively all possible query plans in a large search space, thus a strategy is requisite to produce optimal query plans in distributed database systems. The query plan with most cost-effective option for query processing is measured necessary and must be generated for a given query. This paper attempts to generate such optimal query plans using a parameter less optimization technique Teaching-Learner Based Optimization(TLBO). The TLBO algorithm was experiential to go one better than...
Journal of Magnetism and Magnetic Materials, 2021
Abstract Magnetic properties of N-ion implanted GaN films (150 nm) have been reported. It is foun... more Abstract Magnetic properties of N-ion implanted GaN films (150 nm) have been reported. It is found that GaN films grown by the MOCVD technique show strong room temperature ferromagnetic behavior, which can be tuned by implanting N-ions at different fluences (1 × 1015 to 5 × 1016 ions-cm−2). Presence of implanted N at interstitial sites of the GaN host matrix is indicated from the strain observed in GaN by analysis of XRD data. PL spectra show presence of different types of defects in the as deposited film and engineering of defects after N-ion implantation. XPS spectra of Ga 3d-core level and valence band reveal the bonding of implanted N with the host Ga and/or N. The origin of ferromagnetic behavior is ascribed to unpaired electrons created at N sites due to Ga vacancies. First principle-based calculations also confirm ferromagnetism due to Ga vacancies and the reduction of magnetic behavior in Ga deficient GaN with N-ion implantation at interstitial site. The systematic reduction in the saturation magnetic moment value after N-ion implantation is explained on the basis of pairing of the unpaired electrons due to the bond formation of interstitial N with Ga and N present in the host matrix.
Journal of Molecular Structure, 2021
International Journal of Advanced Research in Biological Sciences (IJARBS), 2017
Xylanase is being utilized in many industries and fruit juice clarification is one of them. The i... more Xylanase is being utilized in many industries and fruit juice clarification is one of them. The industrial use of a free xylanase enzyme is finite because it is expensive and is structurally unbalanced in free form and not stable at high pH and temperature, which can be reduced by entrapment of xylanase upon an insoluble support. Immobilization of xylanase enzyme can be done within sodium alginate beads using entrapment technique. In this study amalgamation of sodium alginate and calcium chloride (0.44 M) was used for the preparation of immobilized beads. After the enzyme is immobilized it is applied on tomato juice which can be obtained by simple extraction .The turbidity and viscosity of juice is due the presence of polysaccharides like cellulose, hemicelluloses, starch, pectin etc. Therefore, juices needs be clarified before commercialization in market. Treatment of tomato juice with xylanase under optimized conditions resulted in an increase in reducing sugars, juice clarity, filterability, pH and but a decline in turbidity and viscosity. Immobilized xylanase was more effective in improving tomato juice overall acceptability and quality as compared to its soluble counterpart. The results showed xylanase, in immobilized form, is a potential candidate for use in fruit juice clarification. The clarity of juice is measured by comparing the transmittance of both samples that is tomato juice treated with xylanase and juice not treated with xylanase.
Ceramics International, 2019
In order to investigate the possible effect of inter-granular strain on the physical properties o... more In order to investigate the possible effect of inter-granular strain on the physical properties of Barium titanate (BaTiO 3), comparative studies have been carried out on the polycrystalline pellet and its corresponding powder samples. For this purpose, the polycrystalline pellet sample of BaTiO 3 has been prepared via conventional solidstate reaction route and powder is obtained by crushing the part of the prepared BaTiO 3 pellet. The comparative room temperature structural studies, temperature dependent optical and Raman spectroscopy measurements have been carried out on the prepared pellet and powder samples. Room temperature X-ray diffraction and Raman analysis confirms the presence of extra amount of strain in pellet sample compared with that of the powder sample. Temperature dependent Raman analysis also suggests the difference in the high temperature tetragonal to cubic transition temperature in both cases. Temperature dependent optical absorption properties measured in terms of Urbach energy (E U), Urbach focus (E 0) and Urbach relaxation clearly indicates the significant change in these quantities for both types of samples on BaTiO 3. Present results strongly reveal the difference in structural, optical and vibrational properties of BaTiO 3 especially across phase transition in pellet and its corresponding powder which clearly shows the importance of inter-granular strain at the grain boundaries.
Journal of Physics: Condensed Matter, 2019
Room temperature optical absorption spectroscopy (OAS) and Raman spectroscopy measurements have b... more Room temperature optical absorption spectroscopy (OAS) and Raman spectroscopy measurements have been carried out in order to understand the effect of structural disorder on the electronic and phononic states. For this purpose, polycrystalline samples of Cr doped PrFeO3 have been prepared via wet chemical route. OAS analysis suggests the systematic scaling of electronic disorder with Cr doping; whereas, shifting in Raman line shapes and an increase in Raman line width has been observed with Cr doping. X-ray diffraction analysis clearly suggests the increase in structural disorders in the form of crystallographic strain with Cr doping, which is consistent with the broadening in Raman line shapes. The major contribution to Raman line width has been understood in terms of temperature independent terms i.e. structural disorder induced by doping. The generation of a new phonon mode at ~510 cm-1 has been observed and understood as a disorder phonon mode due to strain induced structural disorder. Moreover, a systematic correlation between crystallographic strain, Raman line width, disordered parameter (σ) and Urbach energy has been observed, which implies that structural disorder affects phononic as well as electronic states of the system. Such comparative study allows us to find the correlation between densities of tail states, structural disorders and anharmonic effects probed by Raman spectroscopy.
Journal of Applied Physics, 2019
Detailed investigations on the appearance of d-d transitions in optical absorption spectra of YFe... more Detailed investigations on the appearance of d-d transitions in optical absorption spectra of YFeO 3 samples have been done. For this purpose, pure and self-doped (vacancy at Y, Fe, and O sites) YFeO 3 samples have been synthesized using sol-gel, the solid-state reaction route, and hydrothermal synthesis methods. It has been observed that the annealing of prepared samples at different temperatures leads to mixed oxidation states of Fe ions (i.e., the coexistence of Fe ions in mixed valence states such as Fe 2+ /Fe 3+ or Fe 3+ /Fe 4+). Furthermore, soft x-ray absorption (at the Fe L 2,3 edge) and diffuse reflectance spectra analysis revealed that the intensity due to d-d transition is a prominent feature and is strongly associated with the annealing temperatures and the defects present in the samples. Experimental results followed by theoretical analysis carried out using density functional theory suggest that nonstoichiometry of the samples leads to the mixed valency (charge states) of Fe ions and hence to d-d transition in the YFeO 3 (d 5) system.
Advances in Materials and Processing Technologies, 2018
Material research laboratory, discipline of Physics, indian institute of technology indore, indor... more Material research laboratory, discipline of Physics, indian institute of technology indore, indore, india; b indus synchrotron Utilization division, raja ramanna centre for Advanced technology, indore, india; c homi Bhabha national institute, training school complex, Mumbai, india; d computational Analysis division, Bhabha Atomic research centre, visakhapatnam, india
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Papers by 255 VIKASH MISHRA