235 results on '"K. Roy"'
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2. Effects of Hudson River Stressors on Atlantic Tomcod: Contaminants and a Warming Environment
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Isaac Wirgin, R. Christopher Chambers, John R. Waldman, Nirmal K. Roy, David A. Witting, and Mark T. Mattson
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Management, Monitoring, Policy and Law ,Aquatic Science ,Ecology, Evolution, Behavior and Systematics - Published
- 2023
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3. Prediction of soil ecotoxicity against Folsomia candida using acute and chronic endpoints
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R. Paul, J. Roy, and K. Roy
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Drug Discovery ,Molecular Medicine ,Bioengineering ,General Medicine - Published
- 2023
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4. Identification and validation of novel non-nucleoside class of molecules inhibiting the dengue virus replication
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Kuldeep K. Roy, Deeti Jyothi, Udita Paul, and Soumi Sukla
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Structural Biology ,General Medicine ,Molecular Biology - Abstract
There is currently no drug available to treat mosquito-borne dengue. The C-terminal RNA-dependent RNA polymerase (RdRp) domain in the non-structural type 5 (NS5) protein of the dengue virus (DENV) is essential for viral RNA synthesis and replication, and therefore, it is an attractive target for the anti-dengue drug development. We report herein the discovery and validation of two novel non-nucleoside classes of small molecules as DENV RdRp inhibitors. Firstly, using the refined X-ray structure of the DENV NS5 RdRp domain (PDB-ID: 4V0R), we conducted docking, binding free-energy studies, and short-scale molecular dynamics simulation to investigate the binding sites of known small molecules that led to the optimized protein–ligand complex. Subsequently, protein structure-based screening of a commercial database (∼500,000 synthetic compounds), pre-filtered for the drug-likeness, led to the top-ranked 171 molecules, which was then subjected to structural diversity analysis and clustering. This process led to six structurally distinct and best-scored compounds that were procured from the commercial vendor, and then subjected to the in vitro testing in the MTT and dengue infection assays. It revealed two unique and structurally unique compounds, KKR-D-02 and KKR-D-03, exhibiting 84 and 81% reductions, respectively, in DENV copy number in repeated assays in comparison to the virus-infected cell controls. These active compounds represent novel scaffolds for further structure-based discovery of novel candidate molecules for the intervention of dengue. Communicated by Ramaswamy H. Sarma
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- 2023
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5. Decision comfort and student engagement in higher education
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Sanjit K. Roy, Arnold Japutra, Gaganpreet Singh, and Rajdeep Chakraborti
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Marketing ,Education - Published
- 2023
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6. Integer cum fractional ordered active-adaptive synchronization to control vasospasm in chaotic blood vessels to reduce risk of COVID-19 infections
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Piyush P. Singh, Manashita Borah, Asim Datta, Sajad Jafari, and Binoy K. Roy
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Computational Theory and Mathematics ,Applied Mathematics ,Computer Science Applications - Published
- 2023
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7. Understanding casting behaviour of low carbon high manganese steel through detailed characterization of mould powder and mould top slag
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D. Paswan, J. K. Ansu, A. A. Adeleke, P. P. Ikubanni, C. T. Christopher, T. K. Roy, P. Palai, and M. Malathi
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Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys - Published
- 2022
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8. Identification of potential antivirals against 3CLpro enzyme for the treatment of SARS-CoV-2: A multi-step virtual screening study
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V. Kumar, S. Kar, P. De, K. Roy, and J. Leszczynski
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Molecular Docking Simulation ,SARS-CoV-2 ,Drug Discovery ,Humans ,Quantitative Structure-Activity Relationship ,Molecular Medicine ,Protease Inhibitors ,Bioengineering ,General Medicine ,Molecular Dynamics Simulation ,Antiviral Agents ,COVID-19 Drug Treatment - Abstract
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) outbreak is posing a serious public health threat worldwide in the form of COVD-19. Herein, we have performed two-dimensional quantitative structure-activity relationship (2D-QSAR) and three-dimensional pharmacophore modelling analysis employing inhibitors of 3-chymotrypsin-like protease (3CLpro), the leading protease that is crucial for the replication of SARS-CoV-2. The investigation aims to identify the important structural features responsible for the enzyme inhibition and the search for novel 3CLpro enzyme inhibitors as effective therapeutics for treating SARS-CoV-2. Furthermore, we carried out molecular docking studies using the most and least active compounds in the dataset, aiming to validate the contributions of various features as appeared in the QSAR models. Later, the stringently validated 2D-QSAR model was used to estimate the 3CLpro inhibitory activity of compounds from five chemical databases. Compounds with the significant predicted activity were then subjected to pharmacophore-based virtual screening to screen the top-rated compounds, which were then further subjected to molecular docking analysis, absorption, distribution, metabolism, excretion - toxicity (ADMET) profiling, and molecular dynamics (MD) simulation. The multi-step virtual screening analyses suggested that compounds CASAntiV-865453-58-3, CASAntiV-865453-40-3, and CASAntiV-2043031-84-9 could be used as effective therapeutic agents for the treatment of SARS-CoV-2.
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- 2022
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9. Groundwater quality assessment using water quality index in Ranchi Urban area, Jharkhand (India): in parts of Subarnrekha River Basin
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Anukaran Kujur, Goutam K. Roy, Sudhir K. Srivastava, Fakhre Alam, Saumya Anand, and Suresh Kumar
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geography ,geography.geographical_feature_category ,Index (economics) ,Health, Toxicology and Mutagenesis ,010401 analytical chemistry ,Public Health, Environmental and Occupational Health ,Drainage basin ,Soil Science ,010501 environmental sciences ,Urban area ,01 natural sciences ,Pollution ,0104 chemical sciences ,Analytical Chemistry ,Environmental Chemistry ,Environmental science ,Water quality ,Groundwater quality ,Water resource management ,Waste Management and Disposal ,Groundwater ,0105 earth and related environmental sciences ,Water Science and Technology - Abstract
A comprehensive assessment of ground water resources is carried out in the Ranchi Urban Area to understand the hydrogeochemical processes along with assessment of drinking water quality by means of...
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- 2021
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10. Evaluation of different fungicides (chemical, botanical and bio-agent) in controlling wheat blast in a blast prone area in Bangladesh
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Babul Anwar, Naresh Chandra Deb Barma, Pawan K. Singh, P. K. Malaker, Mostofa Ali Reza, Kishowar-E Mustarin, Muzahid-E-Rahman, and Krishna K. Roy
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0106 biological sciences ,Fungicide ,010602 entomology ,Disease severity ,business.industry ,Grain yield ,Biology ,business ,01 natural sciences ,Agronomy and Crop Science ,010606 plant biology & botany ,Biotechnology ,Field conditions - Abstract
This study aimed to evaluate the performance of different fungicides (chemical, botanical and bio-agent) against wheat blast under field conditions and to identify the best one for preventive spray...
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- 2020
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11. First report of triticale blast caused by the fungusMagnaporthe oryzaepathotypeTriticumin Bangladesh
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Kishowar E Mustarin, Xinyao He, Naresh Chandra Deb Barma, Pawan K. Singh, Krishna K. Roy, Mostofa Ali Reza, Muzahid-E-Rahman, P. K. Malaker, and Israil Hossain
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0106 biological sciences ,Horticulture ,Magnaporthe oryzae ,Plant Science ,Fungus ,Cultivar ,Triticale ,Biology ,biology.organism_classification ,Pathogenicity ,01 natural sciences ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
Symptoms of partially bleached and completely white heads were observed in a triticale (× Triticosecale) cultivar ‘BARI Triticale 1ʹ in the research plots at the Regional Agricultural Research Stat...
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- 2020
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12. Effectiveness of B2BC-based SGSC–PGSC and NSC-based SGSC–PGSC in a DFIG-based Grid-connected WT System – A Comparative Study
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A. K. Roy, Subir Datta, and Jyoti Prakash Mishra
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Computer science ,020208 electrical & electronic engineering ,020206 networking & telecommunications ,02 engineering and technology ,Grid ,Turbine ,System a ,Computer Science Applications ,Theoretical Computer Science ,law.invention ,law ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Doubly fed electric machine - Abstract
This paper presents the doubly fed induction generator (DFIG)-based wind turbine (WT) system with a back-to-back converter (B2BC) and nine-switch converter (NSC) as well as their control schemes. A...
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- 2020
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13. A self-consistent systematic optimisation of range-separated hybrid functionals from first principles
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Abhisek Ghosal and Amlan K. Roy
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Chemical Physics (physics.chem-ph) ,Quantum Physics ,Biophysics ,FOS: Physical sciences ,Self consistent ,Condensed Matter Physics ,Topology ,Regular grid ,Hybrid functional ,Range (mathematics) ,Physics - Chemical Physics ,Physical and Theoretical Chemistry ,Quantum Physics (quant-ph) ,Molecular Biology ,Optimal tuning ,Mathematics - Abstract
In this communication, we represent a self-consistent systematic optimization procedure for the development of optimally tuned (OT) range-separated hybrid (RSH) functionals from \emph{first principles}. This is an offshoot of our recent work, which employed a purely numerical approach for efficient computation of exact exchange contribution in the conventional global hybrid functionals through a range-separated (RS) technique. We make use of the size-dependency based ansatz i.e., RS parameter, $\gamma$, is a functional of density, $\rho(\mathbf{r})$, of which not much is known. To be consistent with this ansatz, a novel procedure is presented that relates the characteristic length of a given system (where $\rho(\mathbf{r})$ exponentially decays to zero) with $\gamma$ self-consistently via a simple mathematical constraint. In practice, $\gamma_{\mathrm{OT}}$ is obtained through an optimization of total energy as follows: $\gamma_{\mathrm{OT}} \equiv \underset{\gamma }{\mathrm{opt}} \ E_{\mathrm{tot},\gamma}$. It is found that the parameter $\gamma_{\mathrm{OT}}$, estimated as above can show better performance in predicting properties (especially from frontier orbital energies) than conventional respective RSH functionals, of a given system. We have examined the nature of highest fractionally occupied orbital from exact piece-wise linearity behavior, which reveals that this approach is sufficient to maintain this condition. A careful statistical analysis then illustrates the viability and suitability of the current approach. All the calculations are done in a Cartesian-grid based pseudopotential (G)KS-DFT framework., Comment: 34 pages, 8 tables, 4 figures
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- 2021
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14. Selenium Nanoparticle Protection of Fibroblast Stress: Activation of ATF4 and Bcl-xL Expression
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Amit K. Roy, Thomas J. Webster, and Stanley Chung
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Cell ,Biophysics ,SOD2 ,Pharmaceutical Science ,Bioengineering ,Bcl-xL ,02 engineering and technology ,010402 general chemistry ,medicine.disease_cause ,01 natural sciences ,Biomaterials ,Drug Discovery ,medicine ,chemistry.chemical_classification ,Reactive oxygen species ,biology ,Chemistry ,Cell growth ,Organic Chemistry ,ATF4 ,General Medicine ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Cell biology ,Hsp70 ,medicine.anatomical_structure ,biology.protein ,0210 nano-technology ,Oxidative stress - Abstract
Background In recent years, selenium nanostructures have been researched due to their antibacterial properties, low toxicity to mammalian cells, and high biological efficacy. However, the clinical implementation of the use of selenium has received mixed results, and there is much work needed to improve the understanding of the biological mechanisms involved in the observed cellular responses. Materials and methods In this work, an investigation into the mechanistic pathways of selenium nanoparticles (SeNPs) in biological systems was conducted by studying the changes in gene expression of ATF4, Bcl-xL, BAD2, HSP70, and SOD2 in non-cancerous human dermal fibroblasts (HDF) under oxidative stress, nutrient deprivation stress, and no treatment (control) conditions. Results This study revealed that SeNP incubation led to reduced internal reactive oxygen species (ROS) generation for all conditions tested, thus, providing a protective environment for HDF. At the stress conditions, the expression of ATF4 and Bcl-xL increased for cells treated with SeNP incubation, leading to attenuation of the cells under stress. These results also hint at reductive stress causing a detrimental impact to cell proliferation under routine cell passaging conditions. Conclusion In summary, this study highlights some possible mechanistic pathways implicated in the action of SeNPs that warrant further investigation (specifically, reducing stress conditions for HDF) and continues to support the promise of SeNPs in a wide range of medical applications.
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- 2019
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15. Does democratic local governance facilitate local economic development? Evidence from Bangladesh
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Paritosh K. Roy and Monzur Hossain
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Sociology and Political Science ,media_common.quotation_subject ,05 social sciences ,0211 other engineering and technologies ,021107 urban & regional planning ,02 engineering and technology ,Development ,Local economic development ,Local governance ,Democracy ,0506 political science ,Political science ,Perception ,Development economics ,050602 political science & public administration ,media_common - Abstract
This paper tests whether the improvement of democratic local governance (DLG) positively impacts local economic development (LED). Based on a nationally representative citizen perception survey of ...
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- 2019
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16. Methods for constructing analytic phase function for small spherical particle polydispersions
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Subodh K. Sharma and A. K. Roy
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Particle scattering ,Distribution (number theory) ,Scattering ,Phase (waves) ,Particle ,Phase function ,Statistical physics ,Atomic and Molecular Physics, and Optics ,Mean value theorem ,Mathematics - Abstract
Two ways of constructing analytic phase function for a polydispersion of small spherical non-absorbing particles have been investigated. First one is a straightforward procedure emanating from the implementation of single particle scattering input into the defined polydisperse phase function. This results in an analytic phase function in terms of moments of the distribution. The second approach is a new strategy, based on the Lagrange mean value theorem. A clear understanding of the relationship between these two approaches has been developed. The efficacy and accuracy of the scattering phase functions is illustrated by applying it to a power-law size distributed sphere ensemble.
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- 2019
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17. Structure investigation, enrichment analysis and structure-based repurposing of FDA-approved drugs as inhibitors of BET-BRD4
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Kuldeep K. Roy, Padmaja D. Wakchaure, and Ravichandiran Velayutham
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0301 basic medicine ,Drug ,BRD4 ,Stereochemistry ,media_common.quotation_subject ,Lysine ,Cell Cycle Proteins ,Molecular Dynamics Simulation ,Ligands ,01 natural sciences ,Hydrophobic effect ,03 medical and health sciences ,Protein Domains ,Structural Biology ,Humans ,Molecular Biology ,media_common ,Binding Sites ,Chemistry ,Drug Repositioning ,Proteins ,General Medicine ,Ligand (biochemistry) ,0104 chemical sciences ,Bromodomain ,Molecular Docking Simulation ,010404 medicinal & biomolecular chemistry ,Drug repositioning ,030104 developmental biology ,Pharmaceutical Preparations ,Docking (molecular) ,Drug Design ,Protein Binding ,Transcription Factors - Abstract
We report herein detailed structural insights into the ligand recognition modes guiding bromodomain selectivity, enrichment analysis and docking-based database screening for the identification of the FDA-approved drugs that have potential to be the human BRD4 inhibitors. Analysis of multiple X-ray structures prevailed that the lysine-recognition sites are highly conserved, and apparently, the dynamic ZA loop guides the specific ligand-recognition. The protein-ligand interaction profiling revealed that both BRD2 and BRD4 shared hydrophobic interaction of bound ligands with PRO-98/PRO-82, PHE-99/PHE-83, LEU-108/LEU-92 and direct H-bonding with ASN-156/ASN-140 (BRD2/BRD4), while on the other hand the water-mediated H-bonding of bound ligands with PRO-82, GLN-85, PRO-86, VAL-87, ASP-88, LEU-92, TYR-97 and MET-132, and aromatic π-π stacking with TRP-81 prevailed as unique interaction in BRD4, and were not observed in BRD2. Subsequently, through ROC curve analysis, the best enrichment was found with PDB-ID 4QZS of BRD4 structures. Finally, through docking-based database screening study, we found that several drugs have better binding affinity than the control candidate lead (+)-JQ1 (Binding affinity = -7.9 kcal/mol), a well-known BRD4 inhibitor. Among the top-ranked drugs, azelastine, a selective histamine H1 receptor antagonist, showed the best binding affinity of -9.3 kcal/mol and showed interactions with several key residues of the acetyl lysine binding pocket. Azelastine may serve as a promising template for further medicinal chemistry. These insights may serve as basis for structure-based drug design, drug repurposing and the discovery of novel BRD4 inhibitors. Communicated by Ramaswamy H. Sarma.
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- 2018
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18. Assessment of recovery and recrystallisation behaviours of cold rolled IF steel through non-destructive electromagnetic characterisation
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Siuli Dutta, Swapan K Das, Claire Davis, V. Rajinikanth, Martin Strangwood, Rajat K. Roy, Ashis K. Panda, and Amitava Mitra
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010302 applied physics ,Materials science ,Metallurgy ,Recrystallization (metallurgy) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,law.invention ,Optical microscope ,law ,Non destructive ,0103 physical sciences ,Electron microscope ,0210 nano-technology - Abstract
The recovery and recrystallisation behaviours of cold rolled IF steel have been investigated by destructive (optical microscopy and hardness) and non-destructive electromagnetic sensor, (which allo...
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- 2018
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19. Computational study of the decomposition mechanisms of ammonium dinitramide in the gas phase
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Xiaohu Yu, Lingxia Jin, Rui Wang, Ming-Jing Li, Zhiyin Wang, Tianlei Zhang, Soumendra K. Roy, and Qiong Xu
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010304 chemical physics ,Thermal decomposition ,Biophysics ,010402 general chemistry ,Condensed Matter Physics ,Ammonium dinitramide ,01 natural sciences ,Decomposition ,Transition state ,0104 chemical sciences ,Gas phase ,chemistry.chemical_compound ,Reaction rate constant ,chemistry ,Intramolecular force ,0103 physical sciences ,Physical chemistry ,Physical and Theoretical Chemistry ,Molecular Biology ,Chemical decomposition - Abstract
CBS-QB3 method has been employed to determine the geometries, the vibrational frequencies of the reactants, the products and the transition states involved in intramolecular hydrogen-transfer and decomposition reactions of the free gas-phase H3N···HN(NO2)2 (ADN*). The results show that the intramolecular hydrogen-transfer reaction of ADN* is more feasible than that of HDN. ADN* and its hydrogen-transfer isomers ADN*-IIa,b,c decompose along four channels to form NH3 + HONO + 2NO (PI), ȮH + ṄO3 + N2 + NH3 (PII), ȮH + ṄO2 + N2O + NH3 (PIII), and HNO3 + N2O + NH3 (PIV), respectively. It has been found that the dominant decomposition channels are PI and PIII. The hydrogen-transfer reaction can reduce the barrier of elimination of NO2 and forming N2O reactions in ADN* and HDN. The decomposition of ADN*-IIc to form NO2 and N2O is more feasible than that of the gas-phase HDN. The rate constants (k) of rate-determining step of ADN* show that kPI and kPIII are higher than kPIV and kPII. Compared with HDN-II...
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- 2018
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20. A Study on Durable Flame Retardancy of Jute
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Bhupendra Singh Butola, Samrat Mukhopadhyay, and P. K. Roy
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010407 polymers ,chemistry.chemical_compound ,chemistry ,Materials Science (miscellaneous) ,Tetrakis(hydroxymethyl)phosphonium chloride ,Phosphonium chloride ,Polymer chemistry ,Hydroxymethyl ,02 engineering and technology ,021001 nanoscience & nanotechnology ,0210 nano-technology ,01 natural sciences ,0104 chemical sciences - Abstract
Flame retardancy was imparted to jute fabric through application of organophosphorus flame retardants (OFR) and tetrakis (hydroxymethyl) phosphonium chloride (THPC). The OFR agent was used in conju...
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- 2018
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21. Taking risks for personal gain: An investigation of self-construal and testosterone responses to competition
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Shawn N. Geniole, Shinobu Kitayama, Ashlin R. K. Roy, Keith M. Welker, and Justin M. Carré
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Male ,Competitive Behavior ,Self construal ,Social Psychology ,05 social sciences ,Testosterone (patch) ,Development ,050105 experimental psychology ,Competition (economics) ,Young Adult ,03 medical and health sciences ,Behavioral Neuroscience ,Risk-Taking ,0302 clinical medicine ,Personal gain ,Humans ,Testosterone ,0501 psychology and cognitive sciences ,sense organs ,skin and connective tissue diseases ,Psychology ,Risk taking ,Social psychology ,030217 neurology & neurosurgery - Abstract
Recent research on testosterone and risk-taking behavior is beginning to focus on the role of context-dependent changes in testosterone. Extending this research, our study investigated the association between testosterone reactivity to competitive outcomes and risk-taking in the context of a video game based competition. The study also examined whether self-construal moderated this relationship. Results indicated that a rise in testosterone during competition did not predict subsequent risk-taking behavior. However, a rise in testosterone during competition predicted subsequent risk-taking behaviors within winners with independent self-construals. Nevertheless, results did not reveal an association between basal testosterone and risk-taking, nor did competitive outcomes modulate a differential testosterone response. Overall, we treat these findings as preliminary, as there were multiple analyses conducted and effect sizes were relatively small. We discuss these results in the context of recent animal findings that testosterone facilitates success at future competitions after winning a competition, as well as recent research suggesting self-construal moderates associations between testosterone and aggression.
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- 2017
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22. Operation and control of a DFIG-based grid-connected WECS using NSC during grid fault and with unbalanced non-linear load
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Jyoti Prakash Mishra, A. K. Roy, and Subir Datta
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Engineering ,Renewable Energy, Sustainability and the Environment ,Rotor (electric) ,business.industry ,Stator ,020209 energy ,020208 electrical & electronic engineering ,02 engineering and technology ,Building and Construction ,Fault (power engineering) ,Power (physics) ,law.invention ,Compensation (engineering) ,Voltage compensation ,Control theory ,law ,0202 electrical engineering, electronic engineering, information engineering ,Harmonic ,Electronic engineering ,business ,Voltage - Abstract
This paper proposes a combined feed-forward and selective harmonic compensation-based control scheme for a grid-connected doubly fed induction generator Wind Turbine system using a nine-switch converter (NSC) to improve the performance during grid faults and unbalanced non-linear loading. This is achieved through desired line voltage compensation and/or selective harmonic reduction technique. The two outputs of NSC are controlled such that one functions as a series grid-side converter to inject appropriate voltage in series with stator terminals to maintain the desired stator voltage profile, while the other one functions as a parallel grid-side converter to regulate the DC-link voltage to its reference value irrespective of the direction of flow of rotor power with the conventional rotor side converter. Simulation has been carried out in a MATLAB/Simulink environment. The results show that the proposed scheme ensures the feasibility of improving the Fault Ride Through capability and reducing the ...
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- 2017
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23. Development of ISSR- and RAPD-derived SCAR markers for identification of Gladiolus germplasm
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Tikam Singh Rana, Ashish K. Pal, Baleshwar Meena, Niraj Singh, Sushma Tamta, and R. K. Roy
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0106 biological sciences ,0301 basic medicine ,Germplasm ,biology ,fungi ,food and beverages ,Horticulture ,biology.organism_classification ,Amaryllis ,01 natural sciences ,RAPD ,Crop ,03 medical and health sciences ,030104 developmental biology ,Botany ,Ornamental plant ,Genetics ,Floriculture ,Cultivar ,Gladiolus ,010606 plant biology & botany - Abstract
Gladiolus is an economically important ornamental crop, cultivated for its beautiful flowers throughout the world. The correct genotype identification of plant material is very significant for the floriculture industry. The aim of this study was to develop sequence-characterised amplified region (SCAR) markers from RAPD and ISSR fragments for identification and authentication of Gladiolus germplasm. The SCAR markers developed could be easily employed as valuable tools to identify newly developed Gladiolus cultivars. The SCAR markers, viz. ScG12, ScG34, and ScG36, are specific to the DNA from all 62 Gladiolus cultivars, as they did not amplify the DNA of other taxa of the family Iridaceae, including Iris, Amaryllis, and Narcissus. All three SCAR markers distinguished Gladiolus from other taxa of the family Iridaceae, whereas marker ScAm was specific to the ‘Amethyst’ cultivar. Our results confirmed that this particular SCAR marker distinguished the ‘Amethyst’ cultivar from the other 62 Gladiolus cu...
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- 2017
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24. Role of internal oxidation and iron penta carbonyl formation on creep life of 9Cr-1Mo steel
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Jitendra Kumar Sahu, P K Roy, P.S.M. Jena, and R. K. Rai
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010302 applied physics ,Materials science ,Scanning electron microscope ,Mechanical Engineering ,Effective stress ,Metallurgy ,Metals and Alloys ,Oxide ,Diffusion creep ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,chemistry.chemical_compound ,Creep ,chemistry ,Mechanics of Materials ,0103 physical sciences ,Materials Chemistry ,Ceramics and Composites ,Grain boundary ,0210 nano-technology ,Internal oxidation - Abstract
To understand the cause of discrepancy between predicted creep life through parametric methods using short term creep test data and creep life obtained from long term experiments, 1000 and 10,000 h duration creep tests were conducted on a 9Cr-1Mo grade steel at 550 and 650 °C and the oxide scale, fracture surface and microstructure of the crept specimens were analyzed extensively using scanning electron microscope, electron probe micro analyzer and wavelength dispersive spectrometry. From the creep tests, it is concluded that the discrepancies between predicted creep life and experimental creep life is more pronounced as the stress increases. This is attributed to the sensitivity of scale growth to stress level at both the investigated temperature. Higher scale thickness reduces the effective stress on metal substrate and slows down the creep rate. At 650 °C, significant drop in creep life due to increase in stress from 84 to 92 MPa is attributed to oxygen ingress along grain boundaries, formation...
- Published
- 2017
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25. Increased Viability of Fibroblasts When Pretreated with Ceria Nanoparticles During Serum Deprivation [Corrigendum]
- Author
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Amit K. Roy, Francielli S. Genier, Thomas J. Webster, and Maximilian Bizanek
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Biomaterials ,Andrology ,Chemistry ,Organic Chemistry ,Drug Discovery ,Biophysics ,Pharmaceutical Science ,Nanoparticle ,Bioengineering ,Serum deprivation ,General Medicine - Published
- 2020
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26. International out-migration from Gujarat, India: the magnitude, process and consequences
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K.C. Das, Ram B. Bhagat, Rajiva Prasad, and T. K. Roy
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Economic growth ,Middle East ,Liberalization ,050204 development studies ,05 social sciences ,World War II ,0507 social and economic geography ,language.human_language ,Diaspora ,Emigration ,Immigration policy ,Political science ,0502 economics and business ,Development economics ,language ,Gujarati ,050703 geography ,Oil boom - Abstract
India is known for sending a large number of indentured labour to Africa and Caribbean to work in sugar cane and plantation agriculture during the colonial rule. However, the emigration to the West started after the Second World War, more specifically after 1965, as a result of the liberalisation of immigration policy of US and other western countries. Also, emigration to the Middle East increased rapidly since late1970s as a result of oil boom. Of late, there has been an increase in unskilled and semi-skilled labour emigration from many states of India. Historically Gujarat has been one of the leading states in emigration from of India. It is believed that Gujaratis migrated abroad to work as traders, businessmen, shopkeepers, hoteliers, professionals etc. A comprehensive study of Gujarati emigration which includes the characteristics of emigrants, the individual and household strategies, the process of migration comprising of formal (recruitment agency) and informal channels (family, kin, friends, relig...
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- 2016
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27. Plasma-aminothiols status and inverse correlation of total homocysteine with B-vitamins in arsenic exposed population of West Bengal, India
- Author
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Surajit Das, Jnan Prakash Naskar, Sanjit K Roy, Manisha Chakraborty, Sujoy K Manna, and Ashit K Mukherjee
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Male ,0301 basic medicine ,Veterinary medicine ,Urine ,0302 clinical medicine ,Homocysteine ,Chromatography, High Pressure Liquid ,Aged, 80 and over ,Bangladesh ,education.field_of_study ,Chemistry ,Dipeptides ,General Medicine ,Environmental exposure ,Middle Aged ,Glutathione ,Vitamin B 12 ,Creatinine ,030220 oncology & carcinogenesis ,Environmental chemistry ,Calibration ,Vitamin B Complex ,Female ,Environmental Health ,Adult ,inorganic chemicals ,Environmental Engineering ,Adolescent ,Exposed Population ,Population ,India ,Nutritional Status ,chemistry.chemical_element ,Arsenic ,Young Adult ,03 medical and health sciences ,Folic Acid ,Humans ,Cysteine ,education ,Aged ,Arsenic toxicity ,Drinking Water ,Malnutrition ,Environmental Exposure ,Arsenic contamination of groundwater ,B vitamins ,030104 developmental biology ,Socioeconomic Factors ,Case-Control Studies - Abstract
Chronic arsenic toxicity is a serious environmental health problem across the world. Bangladesh and India (particularly the state of West Bengal) are the worst affected countries with such problem. The present study reports plasma-aminothiols (p-aminothiols) like L-cysteine (L-Cys), cysteinyl glycine (Cys-gly), total homocysteine (t-Hcy) and glutathione (GSH) status, and the inverse relationship of t-Hcy with B-vitamins (B1, B6, B9 and B12) in arsenic exposed population of West Bengal, India. Reverse phase HPLC was used to measure p-aminothiols and serum B-vitamins in different arsenic exposed population. Arsenic in drinking water and urine were measured by flow injection analysis system - Atomic Absorption Spectrometry (FIAS-AAS) and Transversely heated graphite atomizer (THGA-AAS) techniques, respectively. Water arsenic exposure was >50 µg/L in 50% population, of which majority (33.58%) belong to the range of >50-500 µg/L and more than 8% were even >1000 µg/L. Urine arsenic (µg/g creatinine) levels increased with arsenic exposure. The variability among p-aminothiols was also observed with higher exposure to arsenic in drinking water. A significant difference between exposed and control population was noticed for plasma L-Cys. The difference of B-vitamins between the population exposed to 50 µg/L arsenic in drinking water was also found to be significant. B9 and B12 deficiency with increased consumption of arsenic in water corroborates the anemic conditions commonly observed among arsenic exposed population. The aminothiol status indicated oxidative stress in exposed population. This study demonstrated progressive increase in plasma t-Hcy as well as inverse relationships of serum B-vitamins with increased water arsenic concentration.
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- 2016
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28. Work-exposure to PM10and aromatic volatile organic compounds, excretion of urinary biomarkers and effect on the pulmonary function and heme-metabolism: A study of petrol pump workers and traffic police personnel in Kolkata City, India
- Author
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Dipanjali Mazumdar, Rajarshi Chakraborty, Anupa Yadav, Moumita Roy, Surojit Das, B P Chattopadhyay, Sanjit K Roy, and Ashit K Mukherjee
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Environmental Engineering ,Hippuric acid ,General Medicine ,BTEX ,Mandelic acid ,High-performance liquid chromatography ,Toluene ,03 medical and health sciences ,chemistry.chemical_compound ,FEV1/FVC ratio ,0302 clinical medicine ,030228 respiratory system ,chemistry ,Environmental chemistry ,Organic chemistry ,Mercapturic acid ,Benzene ,030217 neurology & neurosurgery - Abstract
This study focused work-exposure to particulate matter ≤ 10 µm (PM10), volatile organic compounds (VOCs) and biological monitoring of major VOCs (BTEX) to observe the significant effects of traffic related pollutants on respiratory and hematological systems of workers engaged in two occupational settings, petrol pumps and traffic areas of Kolkata metropolitan city, India. PM10 was assessed by personal sampling and particle size distribution by 8-stage Cascade Impactor. VOCs were analysed by gas chromatography-flame ionization detector (GC-FID) and five urinary metabolites, trans trans- mercapturic acid (tt-MA), S-phenyl mercapturic acid (SPMA), hippuric acid (HA), mandelic acid (MA) and methyl hippuric acid (MHA) of VOCs, benzene, toluene, ethyl benzene and xylenes (BTEX) by reverse phase high performance liquid chromatography (HPLC). Pulmonary functions test (PFT) was measured Spirometrically. ∂-aminoleavulinic acid (ALA) and porphobilinogen (PBG) in lymphocytes were measured spectrophometrically following column chromatographic separation. High exposure to PM10, having 50% of particles, ≤ 5.0 µm in both the occupational settings. Exposure to toluene was highest in petrol pumps whereas benzene was highest (104.6 ± 99.0 μg m-3) for traffic police personnel. Workplace Benzene is found many fold higher than the National ambient standard. Air-benzene is correlated significantly with pre- and post-shift tt-MA (p < 0.001) and SPMA (p < 0.001) of exposed workers. Blood cell counts indicated benzene induced hematotoxicity. ALA and PBG accumulation in lymphocytes indicated alteration in heme-metabolism, especially among traffic police. Significant reduction of force exploratory volume in one second (FEV1) and forced vital capacity (FVC) of fuel fillers are observed with increased tt-MA and SPMA. Study revealed PFT impairments 11.11% (6.66% restrictive and 2.22% obstructive and combined restrictive and obstructive type, each) among petrol pumps and 8.3% obstructive type among traffic police.
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- 2015
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29. Titania-Coated Magnetite and Ni-Ferrite Nanocomposite-Based RADAR Absorbing Materials for Camouflaging Application
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Ganesh Chandra Nayak, A. K. Roy, S. K. Sahu, Sukanta Das, P. C. Routray, and Himangshu Bhusan Baskey
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Nanocomposite ,Materials science ,Polymers and Plastics ,Scanning electron microscope ,General Chemical Engineering ,Materials Science (miscellaneous) ,Analytical chemistry ,Nanoparticle ,equipment and supplies ,chemistry.chemical_compound ,Magnetization ,chemistry ,Transmission electron microscopy ,Materials Chemistry ,Magnetic nanoparticles ,Ferrite (magnet) ,Composite material ,Magnetite - Abstract
A novel core–shell-structured nanocomposite material based on titanium dioxide-coated magnetite and Ni-ferrite has been prepared for RADAR absorbing application in a X-band region. The coating of magnetic particles with TiO2 was carried out by in situ hydrolysis of titanium tetrabutoxide, and the composite absorber sheets were prepared with epoxy resin. The morphological characterization of the magnetic particles was studied with field emission scanning electron microscope, transmission electron microscope, X-ray diffraction, and vibrating sample magnetometer analysis techniques. The measurement results confirmed the coating of magnetic particles with TiO2 and reduction of the magnetization of magnetite and Ni-ferrite nanoparticles compared with the uncoated ferrite nanoparticles. Distribution of particle inside the matrix was studied with scanning electron microscope. Microwave absorption study in X-band (8–12 GHz) region was carried out with vector network analyzer. Results showed reflection loss values...
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- 2015
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30. Electro-Optical Behavior of a High Birefringence Mesogenic Mixture
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Anuradha Mukhopadhyay, Roman Dabrowski, Molly Dutta Gupta, and S. K. Roy
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Permittivity ,Birefringence ,Chemistry ,Mesogen ,Mesophase ,General Chemistry ,Condensed Matter Physics ,Thermotropic crystal ,Dipole ,Nuclear magnetic resonance ,Chemical physics ,Polarizability ,Liquid crystal ,General Materials Science - Abstract
Liquid crystal mixtures tailored to possess high birefringence (Δn ≥ 0.30) are being currently used extensively in photonic devices. The present work entails the study of electro-optical properties of such a high birefringence mixture (code name: 1770-2). The multicomponent thermotropic mixture, composed of compounds belonging to families of alkylfluoroisothiocyanatotolanes and alkylphenylfluoroisothiocyanatotolanes, exhibits only the nematic mesophase. The thermal variation of electric permittivities (ϵ| and ϵ⊥) at different frequencies has been determined. Using the birefringence data, thermal variation of polarizability has been determined. The variation of the effective average molecular dipole moment μsol of the set-up molecules in solutions of varying concentrations (in%wt) at a particular temperature has been determined and the average molecular dipole moment μiso of the set-up molecules has been obtained. With a view to determine the nature of the molecular association in the mesophase, the molecu...
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- 2015
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31. Mechanical Activation of Al-oxyhydroxide Minerals–A Review
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Rakesh Kumar, T C Alex, S. K. Roy, and S.P. Mehrotra
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Boehmite ,Materials science ,Hydrometallurgy ,Mechanical Engineering ,Metallurgy ,02 engineering and technology ,General Chemistry ,Extractive metallurgy ,Geotechnical Engineering and Engineering Geology ,Bayer process ,020501 mining & metallurgy ,0205 materials engineering ,Economic Geology ,Leaching (metallurgy) ,Gibbsite ,Dissolution - Abstract
Advances in the field of mechanical activation of Al-oxyhydroxide minerals (synthetic as well as in natural bauxites) over the years around the globe are described in this review. An overview of fundamental aspects of mechanical activation with select examples of applications/examples in extractive metallurgy preludes the theme, mechanical activation of Al-oxyhydroxides. The focus is primarily on mechanically induced reactivity of largely used (and most commonly available too) Al-oxyhydroxides viz. gibbsite and boehmite. Reactivity, considered in the context of dissolution in alkali solution and transformations during thermal treatment, is reported to increase with mechanical activation. Available information is collaged to answer the question why/how does the observed effects happen. Gaps in the existing knowledge and prospects in Bayer process are also discussed.
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- 2015
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32. Soil depth estimation through soil-landscape modelling using regression kriging in a Himalayan terrain
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Shraban Sarkar, Tapas R. Martha, and Archana K. Roy
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Soil map ,Topographic Wetness Index ,Soil biology ,Geography, Planning and Development ,Elevation ,Soil science ,Terrain ,Library and Information Sciences ,Soil survey ,Geography ,Spatial variability ,Digital elevation model ,Information Systems ,Remote sensing - Abstract
Soil formation depends upon several factors such as parent material, soil biota, topography and climate. It is difficult to use conventional soil survey methods for mapping the depth of soil in complex mountainous terrains. In this context, the present study aimed to estimate the soil depth for a large area 330.35 km2 using different geo-environmental factors through a soil-landscape regression kriging RK model in the Darjeeling Himalayas. RK with seven predictor variables such as elevation, slope, aspect, general curvature, topographic wetness index, distance from the streams and land use, was used to estimate the soil depth. While topographic parameters were derived from an 8-m resolution digital elevation model, the ortho-rectified Cartosat-1 satellite image was used to prepare the land use map. Soil depth measured at 148 sites within the study area was used to calibrate and validate the RK model. The result showed that the RK model with the seven predictors could explain 67% spatial variability of soil depth with a prediction variance between 0.23 and 0.42 m at the test site. In the regression analysis, land use 0.133 and slope –0.016 were identified as significant determinants of soil depth. The prediction map showed higher soil depth in south-facing slopes and near valleys in comparison to other areas. Mean, mean absolute and root mean-square errors were used to access the reliability of the prediction, which indicated a goodness-of-fit of the RK model.
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- 2013
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33. Volatile Aroma and Antioxidant Quality of ‘Shiraz’ Grapes at Different Stages of Ripening
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N. K. Srinivasa Rao, V. S. Patil, R. H. Laxman, T. K. Roy, K. S. Shivashankara, and G. A. Geetha
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Wine ,Antioxidant ,Ecology ,DPPH ,medicine.medical_treatment ,Ripening ,Plant Science ,Berry ,Horticulture ,Biology ,biology.organism_classification ,Terpenoid ,chemistry.chemical_compound ,Antioxidant capacity ,chemistry ,Botany ,medicine ,Agronomy and Crop Science ,Aroma - Abstract
Wine quality is determined by the stage of harvest of grapes. In order to understand the effect of ripening stages on the berry aroma and antioxidant quality, berries were grouped into three categories, namely: (a) full ripe (before skin shriveling); (b) partially shriveled; and (c) 75% shriveled berries. Total terpenoids, alcohols, hydrocarbons, radical scavenging capacity (DPPH), and total anthocyanins were higher in grapes harvested at full ripe stage, when compared to other stages. Therefore, for better aroma and antioxidants in wines, grapes should be harvested at full ripe (no shriveled berries) stage instead of overripe shriveled berry stages.
- Published
- 2013
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34. A prospective study on role of dehydroepiandrosterone (DHEA) on improving the ovarian reserve markers in infertile patients with poor ovarian reserve
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Neena Malhotra, Jai Bhagwan Sharma, Sunesh Kumar, K. K. Roy, Neeta Singh, Perumal Vanamail, and Rinchen Zangmo
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Adult ,Anti-Mullerian Hormone ,endocrine system ,medicine.medical_specialty ,Pregnancy Rate ,Endocrinology, Diabetes and Metabolism ,medicine.medical_treatment ,India ,Dehydroepiandrosterone ,Fertilization in Vitro ,Follicle-stimulating hormone ,Endocrinology ,Ovarian Follicle ,Ovulation Induction ,Pregnancy ,Humans ,Medicine ,Ovarian reserve ,Prospective cohort study ,Ultrasonography ,Gynecology ,Estradiol ,business.industry ,Ovary ,Age Factors ,Obstetrics and Gynecology ,Fertility Agents, Female ,medicine.disease ,Antral follicle ,Pregnancy rate ,Female ,Follicle Stimulating Hormone, Human ,Ovulation induction ,business ,Infertility, Female ,Poor ovarian reserve ,Biomarkers ,hormones, hormone substitutes, and hormone antagonists - Abstract
The aim of this study was to evaluate the role of dehydroepiandrosterone (DHEA) supplementation on the ovarian reserve markers in infertile patients who were poor responders in previous in vitro fertilization (IVF) cycles.A prospective clinical trial was conducted on 30 patients with history of poor response in previous IVF cycles. These patients were treated with DHEA, (Tab Eema-D, Corona Remedies Pvt Ltd., Ahmedabad, Gujurat, India) 25 mg thrice a day for four months. Ovarian stimulation was done using the previous protocol. Clinical parameters were measured before and treatment with DHEA. Results were analysed using Student's "t" paired test.DHEA resulted in a significant increase (p 0.05) in the serum Antimullerian hormone in all age groups (35, 36-38 and38 years). Peak estradiol level on the day of human chorionic gonadotrophin administration also increased significantly (p 0.05). A significant decrease (p 0.05) was noted in Day 2 follicle-stimulating hormone (FSH) in all age groups. There was no statistically significant difference in the antral follicle count (AFC). Pregnancy rate was 16.7% after treatment. Thus, DHEA has a significant effect in improving the ovarian reserve in poor responders with previously failed IVF cycles. It can help in enhancing clinical pregnancy rate in these patients.
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- 2013
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35. Development of natural dyed jute fabric with improved colour yield and UV protection characteristics
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Sujata Saxena, A. K. Roy, A. Khan, N. C. Pan, and S. N. Chattopadhyay
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Uv protection ,Ferrous sulphate ,Materials science ,Polymers and Plastics ,Alum ,Materials Science (miscellaneous) ,Mordant ,Pulp and paper industry ,Sequential treatment ,Industrial and Manufacturing Engineering ,chemistry.chemical_compound ,chemistry ,Yield (chemistry) ,Composite material ,Dyeing ,General Agricultural and Biological Sciences ,Natural dye - Abstract
Premordanting of jute fabric was carried out following single mordanting by biomordants (myrobolan and pomegranate) and ecofriendly chemical mordants (ferrous sulphate and potash alum) and double mordanting by sequential treatment of biomordant and ecofriendly chemical mordant. Extraction condition of natural dyes from manjistha, annatto, ratanjot and babool was standardised and applied on premordanted jute fabric. There is a substantial improvement of colour yield, levelness of dyeing and wash fastness properties of natural dyed jute fabric after double premordanting using bio and chemical mordant. Light fastness ratings are moderate to good while rubbing fastness are very good to excellent for all the natural dyed jute fabric. Very good ultraviolet (UV) protection ratings are achieved in case of dyeing of jute fabric using natural dyes extracted from manjistha, annatto, ratanjot and babool after premordanting with sequential treatment of biomordant and chemical mordant. UV protection properties of natur...
- Published
- 2013
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36. Unprecedented Halogenation of Biginelli Compounds of Salicyldehyde
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Monoj K. Roy, Sudhir C. Pal, G. Patra, and Sankar C. Bhunia
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Acetic acid ,chemistry.chemical_compound ,Bromine ,chemistry ,Bicyclic molecule ,Organic Chemistry ,chemistry.chemical_element ,Organic chemistry ,Halogenation ,Iodine monochloride - Abstract
Unprecedented results are obtained from bromination of the normal/non-bridged and abnormal/bridged Biginelli compound of salicyldehyde. Bromination with 2,4,4,6-tetrabromocyclohexa-2,5-dienone yields a bridged monobromo-derivative and a bridged dibromo-derivative, respectively, whereas bromination with bromine and acetic acid gives a mixture of those two products in each case. Bromination with N-bromosuccinimide gives a third product, namely a tribromo-derivative, in addition to those two products. Iodination of both the substrates using iodine monochloride (Wijs solution) furnishes a bridged monoiodo-derivative only.
- Published
- 2013
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37. Development of high strength stainless steel brazed joints using rapidly solidified filler alloys
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H Bapari, Abhijit Mitra, Rajat K. Roy, and Ashok Kumar Panda
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Materials science ,Brittleness ,Bond strength ,Metallurgy ,Intermetallic ,Brazing ,General Materials Science ,Condensed Matter Physics ,Base metal ,FOIL method ,Amorphous solid ,Solid solution - Abstract
Two types of rapidly solidified filler alloys of nominal composition Cu–40Mn–10Ni (C50) and Ni–7Cr–3·2B–4·5Si–3Fe (N82) were used for stainless steel (SS304) brazing joints. The C50 foil is crystalline in nature, whereas N82 foil shows amorphous structure. The SS304/C50/SS304 joint shows solid solution phases at interfacial area, with maximum bond strength of 500 MPa, which qualifies to 80% of base metal strength. Conversely, the SS304/N82/SS304 joint develops brittle CrxBy intermetallic phases, which lowers bond strength to 330 MPa.
- Published
- 2013
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38. Sonochemical Synthesis of Polypyrrole Salt and Study of its Cr(VI) Sorption-Desorption Properties
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Pranesh Chowdhury, P. Mondal, K. Roy, and Shyama Prasad Bayen
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chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Scanning electron microscope ,Inorganic chemistry ,chemistry.chemical_element ,Sorption ,General Chemistry ,Polymer ,Polypyrrole ,complex mixtures ,chemistry.chemical_compound ,Chromium ,chemistry ,Chemical engineering ,Desorption ,Materials Chemistry ,Ceramics and Composites ,Selectivity ,Thermal analysis - Abstract
Polypyrrole salt of desired structure has been synthesized sonochemically and characterized by chemical, spectral and thermal analysis. Surface morphology of the polymer is examined by scanning electron microscope (SEM). Chromium(VI) sorption-desorption properties of the polymer has been studied through optimization of pH, contact time and temperature. Selectivity towards Cr(VI) sorption in the presence of competitive ions has been tested. The relevant kinetic parameters are evaluated to elucidate the sorption-desorption mechanism. The metal binding capacity of the polymer is compared with the commercially available ion-exchangers.
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- 2012
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39. Selective Solid Phase Extraction of Chromium(VI) using Silica Gel Immobilized 4-vinyl Pyridine/Cupric Ion Complex
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K. Roy, Prasanta Chowdhury, Stéphane Bayen, and Palash Mondal
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Aqueous solution ,Silica gel ,Process Chemistry and Technology ,General Chemical Engineering ,Metal ions in aqueous solution ,Extraction (chemistry) ,Inorganic chemistry ,chemistry.chemical_element ,Filtration and Separation ,General Chemistry ,chemistry.chemical_compound ,Chromium ,chemistry ,Pyridine ,Solid phase extraction ,Hybrid material - Abstract
Immobilization of 4-vinyl pyridine (4-VP) onto silica gel (SG) and its coordination with cupric ion (SG-4-VP→Cu2+) leading to a new solid phase extractor has been carried out by a simple chemical technique. Immobilization and coordination reactions are characterized by chemical, FTIR, UV, and thermo-gravimetric analysis. The role of cupric ion on Cr(VI) binding capacity of the synthesized organic-inorganic hybrid material has been elucidated. The silica gel immobilized 4-VP/Cu2+ complex (hybrid material) is tested for selective extraction and pre-concentration of Cr(VI) from aqueous solution. The Cr(VI) binding behavior of the synthesized material is studied at different pH, time, and temperature of the medium in both competitive and non-competitive conditions.
- Published
- 2012
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40. The lattice Boltzmann Peierls Callaway equation for mesoscopic thermal transport modeling
- Author
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Jonghoon Lee, Barry L. Farmer, Ajit K. Roy, and Sangwook Sihn
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Physics ,Mesoscopic physics ,Condensed matter physics ,Phonon ,Mean free path ,Thermal resistance ,Lattice Boltzmann methods ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Exponential function ,Mechanics of Materials ,Condensed Matter::Superconductivity ,Interfacial thermal resistance ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Linear approximation ,Civil and Structural Engineering - Abstract
The lattice Boltzmann Peierls Callaway (LBPC) method is a recent development of the versatile lattice Boltzmann formalism aimed at a numerical experiment on mesoscale thermal transport in a multiphase phonon gas. Two aspects of mesoscopic thermal transport are discussed: the finite phonon mean free path and the interface thermal resistance. Based on the phonon momentum screening length measured in the LBPC computational apparatus, the validity of the Umklapp collision relaxation time in the Callaway collision operator is examined quantitatively. The discrete nature of the spatio-temporal domain in the LBPC method, along with the linear approximation of the exponential screening mechanism in the Callaway operator, reveals a large discrepancy between the effective phonon mean free path and the analytic phonon mean free path when the relaxation time is small. The link bounce back interface phonon collision rule is used to realize the interface thermal resistance between phonon gases with dissimilar dispersio...
- Published
- 2011
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41. Use of spacer aided initiation technique in solid blasting in Indian underground coal mines
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S K Roy and R R Singh
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Engineering ,Explosive material ,Waste management ,business.industry ,General Engineering ,Coal mining ,Geology ,Geotechnical Engineering and Engineering Geology ,complex mixtures ,Mining engineering ,General Earth and Planetary Sciences ,business ,General Environmental Science ,Rock blasting - Abstract
Solid blasting mining methods contribute about 60% of total underground coal production in India. Spacer aided initiation technique utilises the inherent air gap sensitivity of the explosive to distribute the blast energy over a longer length by the use of air decking using plastic spacers with single priming to achieve higher pull in solid blasting. The results of exploratory field trials of the use of spacer aided initiation technique in solid blasting with a specially developed Pentadyne‐HP explosive conducted in an underground mine concluded that it was possible to achieve a pull of up to 2·2 m and yield up to 41 t per blast in a development face. Based on results of the studies conducted by authors, statutory authority for mines safety in India granted approval for commercial use of this technique with Pentadyne‐HP explosive in all the degree I gassy underground coal mines.
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- 2011
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42. Species Variability for Fruit Antioxidant and Radical Scavenging Abilities in Mulberry
- Author
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T. K. Roy, S. H. Jalikop, and K. S. Shivashankara
- Subjects
Antioxidant ,Ecology ,biology ,medicine.medical_treatment ,Plant Science ,Horticulture ,biology.organism_classification ,Ascorbic acid ,chemistry.chemical_compound ,chemistry ,Anthocyanin ,Botany ,medicine ,Caffeic acid ,Ferric ,Phenols ,Gallic acid ,Food science ,Agronomy and Crop Science ,Morus nigra ,medicine.drug - Abstract
Fruits from five accessions of mulberry (Morussp.) representing Morus nigra, Morus lavigeta, and Morus alba were evaluated for ferric reducing antioxidant potential, diphenyl picryl hydrazyl radical scavenging ability, total phenols, flavonoids, anthocyanins, and ascorbic acid contents. In fresh fruits, higher antioxidant capacity was found in M. nigra followed by M. lavigeta and the lowest capacity was observed in M. alba. Higher ferric reducing antioxidant potential and diphenyl picryl hydrazyl scavenging capacities were mainly due to higher anthocyanins. Among the black accessions evaluated, Acc. No. 362 and 497 recorded the highest ferric reducing antioxidant potential (4,515.75 and 4,224.24 mg ascorbic acid equivalent antioxidant capacity 100 g−1 dry wt, respectively), diphenyl picryl hydrazyl (IC50 values of 0.124 and 0.116 mg−1, respectively), and anthocyanin (4,255.65 and 4,103.93 mg/100 g−1 dry wt, respectively) content when compared to other accessions. Accession number 249 (M. alba) with white ...
- Published
- 2010
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43. A Dynamical Statistical Model for Prediction of a Tropical Cyclone
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S. D. Kotal and S. K. Roy Bhowmik
- Subjects
Low-pressure area ,Geography ,Meteorology ,Climatology ,Statistical model ,Ranging ,Cyclone Nargis ,Numerical models ,Tropical cyclone forecast model ,Tropical cyclone ,Oceanography ,Intensity (heat transfer) - Abstract
A dynamical statistical method is applied for operational forecasting of the Bay of Bengal tropical cyclone “Nargis” of April–May 2008. The method consists of three forecast components, namely (a) analysis of Genesis Potential Parameter (GPP) and maximum potential intensity, (b) track prediction, and (c) 12 hourly intensity prediction for forecasts up to 72 hours. The results of the study showed that GPP could provide necessary predictive signal at early stages of development on the further intensification of the low pressure system into a tropical cyclone. The landfall forecast position errors by different operational numerical models (NWP) showed landfall position errors ranging from 10 km to 150 km and landfall time error ranges from 6 hours early to 6 hours delay. The dynamical statistical model is capable to provide 12 hourly nearly realistic intensity forecasts up to 60 hours of forecast.
- Published
- 2010
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44. Finishing of Jute Fabric for Value-Added Products
- Author
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A. K. Roy, S. N. Chattopadhyay, A. Khan, and N. C. Pan
- Subjects
Materials science ,Bleach ,Materials Science (miscellaneous) ,Optical property ,Pulp and paper industry ,Physical property ,chemistry.chemical_compound ,chemistry ,Ultimate tensile strength ,Reactive dye ,Nonionic surfactant ,Composite material ,Dyeing ,Value added - Abstract
Gray jute fabric has been bleached by three different processes—gray-bleach, scour bleach, and gray ambient bleach—to produce white fabric. These processes produce different optical and physical properties. All the bleached jute fabrics were dyed with direct and reactive dyes. Bleached and dyed jute fabrics were padded with finishing formulation comprising resin, softener, and nonionic surfactant, subsequently dried and cured. An evaluation of the bleached jute fabric reveals that the finishing treatment resulted in very good creasing characteristics without much deterioration of tensile strength. There is no alteration in color of the bleached and dyed jute fabrics before and after the finishing treatment. Washing fastness of the finished fabric is also good. Therefore, this combined finishing treatment can be applied to jute fabric to produce diversified and value-added jute products.
- Published
- 2010
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45. An Analysis of Surface Temperature Rise at the Contact between Sliding Bodies with Small-Scale Surface Roughness
- Author
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S. K. Roy Chowdhury and Sudipto Ray
- Subjects
Materials science ,Optics ,Mechanics of Materials ,business.industry ,Mechanical Engineering ,Surface roughness ,Contact temperature ,Surfaces and Interfaces ,Surface finish ,Composite material ,business ,Surfaces, Coatings and Films ,Parametric statistics - Abstract
A theoretical model for analyzing surface temperature rise between extremely smooth sliding bodies considering the effect of adhesion forces on the contact conditions is developed. The important observation is that in addition to the dependence on load, speed, and material parameters the contact temperature steadily increases with surface adhesion. In the nanometric range of asperity heights contact temperature rise drops to some extent with the increase in roughness whereas in the micro- or macroscale surface roughness, the temperature rise steadily increases with surface roughness. Under certain combinations of load, speed, and material parameters extremely high contact temperature rise is predicted, whereas under certain other parametric combinations extremely low temperature rise may occur. The latter parametric combination is of significant practical importance.
- Published
- 2010
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46. Study on the Effect of Nano and Active Particles of Alumina on Natural Rubber–Alumina Composites in the Presence of Epoxidized Natural Rubber as Compatibilizer
- Author
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T. K. Pariya, B. B. Konar, and S. K. Roy
- Subjects
Materials science ,Polymers and Plastics ,Kinetics ,Vulcanization ,Nanoparticle ,General Chemistry ,law.invention ,Reaction rate constant ,Natural rubber ,law ,visual_art ,Nano ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,Particle size ,Composite material ,Curing (chemistry) - Abstract
Natural rubber composites with alumina of different particle sizes (28 nm nano particles, 200 nm active particles and > 1000 nm raw alumina) were prepared by the usual rubber processing technique. Epoxidized natural rubber (ENR) was used in the composites as compatibilizer. Cure characteristics and mechanical properties of all composites were analyzed. The values of minimum rheometric torque (ML), maximum rheometric torque (MH) and torque difference (MH – ML) increased. Maximum enhancement was observed for the nano-filled composites. It endorses the view that nano alumina reveals highest interaction with natural rubber in presence of ENR. Scorch time and optimum cure time values for nano-composites were highest among all types of composites. Vulcanization reaction for the sulfur curing system of the composites was found to follow first order rate kinetics. Specific rate constant decreased with decreasing particle size in composites. Crosslink densities of composite-vulcanizates showed increasing trend wit...
- Published
- 2010
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47. Mitochondrial stress and the pathogenesis of diabetic neuropathy
- Author
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Robert E. Schmidt, Paul Fernyhough, and Subir K. Roy Chowdhury
- Subjects
chemistry.chemical_classification ,Reactive oxygen species ,Pathology ,medicine.medical_specialty ,Autonomic nerve ,Diabetic neuropathy ,business.industry ,Endocrinology, Diabetes and Metabolism ,Neurodegeneration ,Context (language use) ,Mitochondrion ,Bioinformatics ,medicine.disease ,Article ,Mediator ,chemistry ,Diabetes mellitus ,medicine ,business - Abstract
Diabetic neuropathy is a major complication of diabetes that affects the sensory and autonomic nervous systems and leads to significant morbidity and impact on quality of life of patients. Mitochondrial stress has been proposed as a major mediator of neurodegeneration in diabetes. This review briefly summarizes the nature of sensory and autonomic nerve dysfunction and presents these findings in the context of diabetes-induced nerve degeneration mediated by alterations in mitochondrial ultrastructure, physiology and trafficking. Diabetes-induced dysfunction in calcium homeostasis is discussed at length and causative associations with sub-optimal mitochondrial physiology are developed. It is clear that across a range of complications of diabetes that mitochondrial physiology is impaired, in general a reduction in electron transport chain capability is apparent. This abnormal activity may predispose mitochondria to generate elevated reactive oxygen species (ROS), although experimental proof remains lacking, but more importantly will deleteriously alter the bioenergetic status of neurons. It is proposed that the next five years of research should focus on identifying changes in mitochondrial phenotype and associated cellular impact, identifying sources of ROS in neurons and analyzing mitochondrial trafficking under diabetic conditions.
- Published
- 2010
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48. Comparative Study of the Optical Properties of two Mesogenic Mixtures Containing Identical Moieties
- Author
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Anuradha Mukhopadhyay, Dutta Gupta, and S. K. Roy
- Subjects
Biphenyl ,Birefringence ,Cyclohexane ,Chemistry ,Mesogen ,General Chemistry ,Condensed Matter Physics ,Thermal variation ,chemistry.chemical_compound ,Crystallography ,Polarizability ,Liquid crystal ,Organic chemistry ,General Materials Science - Abstract
Optical properties of two mesogenic mixtures, code names ZLI 1221and ZLI 1291, possessing same constituents but exhibiting distinct nematic behavior, have been studied. Since both the mixtures possess identical moieties: phenyl cyclohexane, biphenyl cyclohexane and cyclohexyl benzoate, but in different proportions, and exhibit different mesogenic ranges, comparative study of their properties is of great interest. In this work we present a study of the thermal variation of their optical behavior. The variation of polarizability in terms of molecular weight has been obtained for both the mixtures and the thermal dependence of their orientational order parameters have been determined and compared.
- Published
- 2009
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49. Dyeing of Jute Fabric Using Indigosol Dyes
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S. N. Chattopadhyay, A. Khan, N. C. Pan, and A. K. Roy
- Subjects
chemistry.chemical_compound ,Materials science ,chemistry ,Active agent ,Materials Science (miscellaneous) ,Composite material ,Dyeing ,Sodium carbonate ,Pulp and paper industry - Abstract
Bleached jute fabric has been dyed with three indigosol dyes, namely Indigosol Violet I4R, Indigosol Golden Yellow IGK, and Indigosol Blue O4B, having different sensitivity to oxidation. Development stage (i.e., oxidation, neutralization, and soaping of the dyed fabric) plays the most important role for dyeing of jute fabric with indigosol dyes. Concentrations of chemicals in different processing steps such as sodium nitrite in the dye bath, sulphuric acid in the developing bath, sodium carbonate in the neutralization bath, and non-ionic surface active agent in the soaping bath have been optimized. Color yield and fastness properties are found to be better if dyeing and developing steps are carried out separately. Retention of tensile strength of indigosol-dyed jute fabric is sufficient enough for its further use in making diversified and value-added products. Moreover, the handle property of the indigosol-dyed jute fabric is found to be good.
- Published
- 2009
- Full Text
- View/download PDF
50. Artificial Neural Network Approach to Segregation Characteristic of Binary Heterogeneous Mixtures in Promoted Gas-Solid Fluidized Beds
- Author
-
Abanti Sahoo and G K Roy
- Subjects
Physics::Fluid Dynamics ,Work (thermodynamics) ,Materials science ,Chromatography ,Artificial neural network ,General Chemical Engineering ,Distributor ,Binary number ,Gas solid ,Mechanics ,Fluidization ,Coaxial ,Dimensionless quantity - Abstract
Binary mixtures of particles of the same size but of different densities are fluidized in a 15 cm diameter column with a perforated plate distributor and two coaxial promoters. In the present work an attempt has been made to study the fluidization and the segregation characteristic of density-variant solids of the same size in terms of segregation distance. The dimensionless segregation distance has been correlated with other dimensionless groups relating to various system parameters: ratio of the density of jetsam particles to that of flotsam, initial static bed height, height of layer of particles above the bottom grid, superficial gas velocity, and average density of the mixture on the basis of the dimensional analysis approach for both un-promoted and promoted beds. Correlations have also been developed with the above system parameters by using an artificial neural network approach for different types of fluidized beds, and the findings with respect to both approaches have been compared with each othe...
- Published
- 2008
- Full Text
- View/download PDF
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