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Chandigarh, India

Rani N.,MCM DAV College | Tomar S.K.,Panjab University
Journal of Mechanics | Year: 2012

A problem of thermal instability of a compressible micropolar fluid layer heated from below in the presence of suspended particles has been investigated. Dispersion relation is derived and Rayleigh number curve is then plotted against the wavenumber at different values of compressibility parameter for a model example. Compressibility is found to be responsible to destabilize the system in the presence and absence of suspended particles for both stationary and over stationary convection. © 2011 The Society of Theoretical and Applied Mechanics, R.O.C. Source

Rani N.,MCM DAV College | Tomar S.K.,Panjab University
Journal of Electrostatics | Year: 2015

The onset of instability in a layer of dielectric micropolar fluid under the simultaneous action of an AC electric field and temperature gradient has been investigated. The dispersion relation has been derived and various critical values of non-dimensional Rayleigh number in the fluid layer have been determined. The influence of micropolar viscosity and electric Rayleigh number on the onset of convection has been analyzed. Thermal Rayleigh number has been computed for various values of electric Rayleigh number for the onset of instability. The stabilizing and destabilizing effects of electric Rayleigh number, micropolar viscosity and Prandtl number have been discussed. © 2015 Elsevier B.V. Source

Sen R.,Purdue University | Sen R.,MCM DAV College | Raychoudhury R.,Purdue University | Raychoudhury R.,Indian Institute of Science | And 8 more authors.
PLoS ONE | Year: 2015

Previous studies in lower termites revealed unexpected synergies between nicotinoid insecticides and fungal entomopathogens. The present study investigated molecular mechanisms of nicotinoid-pathogen synergy in the lower termite Reticulitermes flavipes, using the nicotinoid, imidacloprid, in combination with fungal and bacterial entomopathogens. Particular focus was placed on metatranscriptome composition and microbial dynamics in the sym-biont-rich termite gut, which houses diverse mixes of protists and bacteria. cDNA microarrays containing a mix of host and protist symbiont oligonucleotides were used to simultaneously assess termite and protist gene expression. Five treatments were compared that included single challenges with sublethal doses of fungi ( Metharizium anisopliae), bacteria (Serratia marcescens) or imidacloprid, and dual challenges with fungi + imidacloprid or bacteria + imidacloprid. Our findings point towards protist dysbiosis and compromised social behavior, rather than suppression of stereotypical immune defense mechanisms, as the dominant factors underlying nicotinoid-pathogen synergy in termites. Also, greater impacts observed for the fungal pathogen than for the bacterial pathogen suggest that the rich bacterial symbiont community in the R. flavipes gut (>5000 species-level phylotypes) exists in an ecological balance that effectively excludes exogenous bacterial pathogens. These findings significantly advance our understanding of antimicrobial defenses in this important eusocial insect group, as well as provide novel insights into how nicotinoids can exert deleterious effects on social insect colonies. Copyright:© 2015 Sen et al. Source

Sharma N.,Jaypee University of Information Technology | Sharma N.,MCM DAV College | Sharda S.,University Baddi | Sharma V.,Jaypee University of Information Technology | Sharma P.,Jaypee University of Information Technology
Journal of Thermal Analysis and Calorimetry | Year: 2015

Tellurium-based glasses are suitable for storage devices due to their rapid amorphous-to-crystalline transformation. Alloys of Ge 19-y Se 63.8 Sb 17.2 Te y (y = 0, 2, 4, 6, 8, 10 at.%) have been synthesized using melt quench technique. Glass transition and crystallization kinetics of alloys have been investigated using differential thermal analysis at different heating rates (5, 10, 15, and 20 K min-1). The thermal stability of synthesized alloys has been investigated. Resistance to devitrification has been analyzed on the basis of activation energy for crystallization. © 2014 Akadémiai Kiadó, Budapest, Hungary. Source

Sachdeva R.,MCM DAV College | Singh B.,Chandigarh Institute of Microbial Technology
Progress in Biophysics and Molecular Biology | Year: 2014

Aquaporin family comprises of transmembrane channels that are specialized in conducting water and certain small, uncharged molecules across cell membranes. Essential roles of aquaporins in various physiological and pathophysiological conditions have attracted great scientific interest. Pioneering structural studies on aquaporins have almost solved the basic question of mechanism of selective water transport through these channels. Another important structural aspect of aquaporins which seeks attention is that how the flow of water through the channel is regulated by the mechanism of gating. Aquaporins are also regulated at the protein level, i.e. by trafficking which includes changes in their expression levels in the membrane. Availability of high resolution structures along with numerous molecular dynamics simulation studies have helped to gain an understanding of the structural mechanisms by which water flux through aquaporins is controlled. This review will summarize the highlights regarding structural features of aquaporins, mechanisms governing water permeation, proton exclusion and substrate specificity, and describe the structural insights into the mechanisms of aquaporin gating whereby water conduction is regulated by post translational modifications, such as phosphorylation. © 2014 Elsevier Ltd. Source

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