Guwāhāti, India
Guwāhāti, India

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Singha T.,Indian Institute of Technology Guwahati | Dutta K.,Handique Girls College | Nandy M.K.,Indian Institute of Technology Guwahati
Journal of Physics A: Mathematical and Theoretical | Year: 2017

We apply a renormalized perturbative scheme to the Navier-Stokes equation for an incompressible isotropic turbulent velocity field. This allows us to obtain the renormalized expressions for second- and third-order cumulants of the velocity derivative directly from the corresponding Feynman diagrams. The resulting expressions are integrated numerically by excluding and including the dissipation range assuming Kolmogorov and Pao's phenomenological expressions for the energy spectrum. The ensuing values for skewness are found to be S = -0.647 (when the dissipation range is excluded) and (when the dissipation is included). These estimated values are compared with various experimental, numerical and theoretical results. © 2017 IOP Publishing Ltd.


Singh R.,Indian Institute of Technology Guwahati | Dutta K.,Handique Girls College | Nandy M.K.,Indian Institute of Technology Guwahati
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2017

A recent theoretical study [Phys. Rev. Lett. 112, 037202 (2014)10.1103/PhysRevLett.112.037202] has revealed that systems such as uranium ferromagnetic superconductors obey conserved dynamics. To capture the critical behavior near the paramagnetic to ferromagnetic phase transition of these compounds, we study the conserved critical dynamics of a nonlocal Ginzburg-Landau model. A dynamic renormalization-group calculation at one-loop order yields the critical indices in the leading order of ϵ=dc-d, where dc=4-2ρ is the upper critical dimension, with ρ an exponent in the nonlocal interaction. The predicted static critical exponents are found to be comparable with the available experimentally observed critical exponents for strongly uniaxial uranium ferromagnetic superconductors. The corresponding dynamic exponent z and linewidth exponent w are found to be z=4-ρϵ/4+O(ϵ2) and w=1+ρ+3ϵ/4+O(ϵ2). © 2017 American Physical Society.


Singh R.,Indian Institute of Technology Guwahati | Dutta K.,Handique Girls College | Nandy M.K.,Indian Institute of Technology Guwahati
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2015

A modified Ginzburg-Landau model with a screened nonlocal interaction in the quartic term is treated via Wilson's renormalization-group scheme at one-loop order to explore the critical behavior of the paramagnetic-to-ferromagnetic phase transition in perovskite manganites. We find the Fisher exponent η to be O(ε) and the correlation exponent to be ν=12+O(ε) through epsilon expansion in the parameter ε=dc-d, where d is the space dimension, dc=4+2σ is the upper critical dimension, and σ is a parameter coming from the nonlocal interaction in the model Hamiltonian. The ensuing critical exponents in three dimensions for different values of σ compare well with various existing experimental estimates for perovskite manganites with various doping levels. This suggests that the nonlocal model Hamiltonian contains a wide variety of such universality classes. © 2015 American Physical Society. ©2015 American Physical Society.


Choudhury M.,Handique Girls College | Mahanta L.B.,Institute of Advanced Study in Science and Technology | Goswami J.S.,Handique Girls College | Mazumder M.D.,Handique Girls College
Food Control | Year: 2011

Successful food hygiene training and the consent of safe food handling practices learnt during training are critical elements in the control of food-borne illnesses throughout the world. It is true for food handlers and vendors belonging to all sectors. But, it is all the more urgent for street vendors because they are more exposed to environmental hazards and are predominantly from much weaker socio-economic backgrounds and yet cater to the general mass. Using a cross-sectional study design a sample of 80 street food vendors were selected and provided with training to evaluate the existing Knowledge, Attitude and Practice (KAP) regarding food safety and hygiene and the change of the same after training interventions. Responses regarding KAP on food safety and hygiene before and after training revealed that there was a significant change in their perception to food safety knowledge and also practices. The knowledge level of the food vendors increased from an average 24.35%-66.2% after training interventions. The overall performance rating of full adoption of good hygiene practices by the vendors ranged from 37.5% to 50.8% in post-training period. © 2011 Elsevier Ltd.


Choudhury M.,Handique Girls College | Mahanta L.,Institute of Advanced Study in Science and Technology | Goswami J.,Handique Girls College | Mazumder M.,Handique Girls College | Pegoo B.,Handique Girls College
Food Control | Year: 2011

Street food is an integral part of society in all countries - underdeveloped, developing or developed. As such the standard of hygiene maintained is a very vital matter. Every region has its sets of factors affecting the hygiene maintain. In the present study a survey was carried out in Guwahati city to determine the existing socio-economic status and food safety knowledge of street food vendors. Data on socio-economic and business profile of 80 vendors were collected using three standardized proformas. A study was also conducted on the existing knowledge of vendors on food safety and hygiene practices and methods of procurement of raw materials. The knowledge and procurement practices of the vendors were assessed for association with some relevant socio-economic factors. From the study it was observed that majority of street food vendors were mobile food vendors (54%) with the remaining being owners of small restaurants and food handlers. Majority of the food vendors were local to Guwahati city (93%). The average daily income of the mobile food vendors were between Rs. 200 to Rs. 600. It also was noted that only 30%-37% vendors were aware of hygienic practices of food handling and a mere 8%-11% of food vendors had knowledge on biological sources of food contamination. It was concluded that there is a high degree of association between procurement practices with the type of vendors, ownership status and average income. But no outstanding association exists with any socio-economic factor with the knowledge of the vendors on food hygiene. The street food scenario in the city was found to be quite dismal and requires stringent steps to improve matters. © 2010 Elsevier Ltd.


Phukan K.,Handique Girls College | Devi N.,Cotton College
International Journal of ChemTech Research | Year: 2012

A general, efficient and simple methodolgy for biocatalytic reduction of a diverse set of carbonyl compounds at room temperature using freshly cut ripen fruit of Lycopersicumesculentum (tomato) in aqueous medium has been reported. It was found that in addition to reduction of simple carbonyls to the corresponding primary and secondary alcohols, the prochiral ketones,both cyclic and acyclic, could be reduced to chiral secondary alcohols in a generalized way. Very high enantioselectivity (92-99%) with moderate to excellent chemical yields (70-95%) were observed. Most of the reductions were completed within 25-35 h. The regioselectivity of the biocatalyst is well established by the reduced product of cinnamaldehyde where the C = C bond was not reduced in the present investigation. The synthesized products were characterized by melting points, TLC, FT-IR and 1H NMR data. Mild reaction condition, simple operation, and easy availability of tomato fruit reveal this protocol as an attractive and alternative eco-friendly option for general reduction of all types of carbonyl compounds.


Senapati U.S.,Handique Girls College | Sarkar D.,Gauhati University
Indian Journal of Physics | Year: 2014

We report here green synthesis of ZnS nanoparticles using the extract of an edible mushroom (Pleurotuss ostreatu). The obtained ZnS nanoparticles are characterized by X-ray diffraction, energy dispersive analysis of X-rays, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, UV-Vis optical absorption, photoluminescence and Fourier Transform Infrared Spectroscopy. XRD analysis confirms ZnS nanoparticles have cubic structure and also there is decrease of particle size and increase of dislocation density and strain with increase of amount of mushroom extract. The variation of crystallite size is in conformity with the results obtained from SEM and TEM. UV-Vis and photoluminescence spectra give the characteristic peak for ZnS nano where as Fourier transform infrared spectra confirm the presence of microbial proteins. © 2014 Indian Association for the Cultivation of Science.


Sarkar T.,Handique Girls College | Banerjee S.,Indian Institute of Science | Hussain A.,Handique Girls College
RSC Advances | Year: 2015

Six new mixed-ligand cobalt(iii) complexes of formulation [Co(N-N)2(O-O)](ClO4)2 (1-6), where N-N is a N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1, 2), dipyrido[3,2-d:2',3'-f]quinoxaline (dpq in 3, 4), and dipyrido[3,2-a:2',3'-c]phenazine (dppz in 5, 6), O-O is acetylacetonate (acac in 1, 3, 5) or curcumin (bis(4-hydroxy-3-methoxyphenyl)-1,6-diene-3,5-dione, cur in 2, 4, 6), have been synthesized and characterized. The X-ray crystal structures of complex 1 (as PF6 - salt, 1a) and 3 show distorted octahedral geometries formed by the CoN4O2 core. The complexes 1, 3 and 5 having the simple acac ligand are prepared as control species to understand the role of curcumin. The optimized geometries and the frontier orbitals of the curcumin complexes 2, 4, and 6 are obtained from the DFT calculations. The complexes 2, 4, and 6 having the photoactive curcumin moiety display an absorption band in the visible region near 420 nm and show remarkable photocytotoxicity in HeLa cancer cells with respective IC50 values of 7.4 μM, 5.1 μM and 1.6 μM while being much less toxic in dark. MTT assay using complex 6 shows that it is not significantly photocytotoxic to MCF-10A normal cells. The control complexes having the acac ligand are non-toxic both in the presence and absence of light. The cell death is apoptotic in nature and triggered by the photogeneration of reactive oxygen species. Fluorescence imaging experiments on HeLa cells reveals that complex 6 accumulated primarily inside the mitochondria. Human serum albumin (HSA) binding experiments show that the complexes bind HSA with good affinity, but 6 binds with the highest affinity, with a Kb value of 9.8 × 105 M-1. Thus, complex 6 with its negligible toxicity in the dark and in normal cells but remarkable toxicity in visible light holds significant photochemotherapeutic potential. © 2015 The Royal Society of Chemistry.


Purkayastha A.D.,Handique Girls College
Pramana - Journal of Physics | Year: 2013

The purpose of this paper is to examine the energy content of the inflationary Universe described by Kantowski-Sachs space-time in quasilocal approach of teleparallel gravity and in the Hamiltonian structure of the teleparallel equivalent of general relativity. The teleparallel versions of field equations are also derived in such a space-time. © Indian Academy of Sciences.


Chakrabarty D.,Handique Girls College
International Journal of Agricultural and Statistical Sciences | Year: 2014

A method has been framed for determining the natural limits (lower limit and upper limit) of annual total rainfall at a location by the application of the area property of Gaussian distribution. The method has been applied in determining the natural limits of annual total rainfall in the context of India.

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