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Upadhyaya H.,Assam University | Upadhyaya H.,Karimganj College | Panda S.K.,Assam University | Dutta B.K.,Assam University
Plant Cell Reports | Year: 2011

Drought stress affects the growth and productivity of the tea plant. However, the damage caused is not permanent. The present investigation studies the effect of CaCl2 on antioxidative responses of tea during post-drought recovery. Increase in dry mass, proline and phenolic content of leaf with decrease in H2O2 and lipid peroxidation and increased activities of enzymes such as SOD, CAT, POX and GR in response to increased foliar CaCl2 concentration are indications for the recovery of stress-induced oxidative damage and thus improving post-stress recovery potential of Camellia sinensis genotypes. © 2010 Springer-Verlag.


Sarkar N.K.,Karimganj College
Vibrational Spectroscopy | Year: 2016

In this study, I report a successful application of the U(4) algebraic model in the vibrational spectral analysis of the isotopic species of nitrosyl halides. With a detailed spectral analysis, it has been shown in this study that all the isotopic species of NOF, NOCl, NOBr and NOI can be approximated very well using the U(4) algebraic model in its strict local limit. © 2016 Elsevier B.V.


Sen R.,Srikishan Sarda College | Kalyan A.,Srikishan Sarda College | Sarkar N.K.,Karimganj College | Bhattacharjee R.,Assam University
Fullerenes Nanotubes and Carbon Nanostructures | Year: 2013

The vibrational energy levels of C 20isomers are calculated considering the local Hamiltonian of Morse potential using the U(2) Lie algebra. Here each bond of the molecule is replaced by a corresponding Lie algebra. Finally the local Hamiltonian is constructed considering the interacting Casimir and Majorana invariant operators. By constructing the Hamiltonian, we calculate the local mode vibrational energy levels of C 20 isomers and thus compare the accuracy of algebraic model with PM3 model. © 2013 Taylor & Francis Group, LLC.


Upadhyaya H.,Karimganj College | Dutta B.K.,Assam University | Panda S.K.,Assam University
Journal of Agricultural and Food Chemistry | Year: 2013

Zinc (Zn) is an essential micronutrient that affects the growth and productivity of tea plant. Drought stress causes various biochemical and physiological damages in plants. The present study aims at understanding the role of Zn in modulating drought stress induced growth and biochemical damages in tea plant. The results of the present investigation demonstrated that drought-induced decrease in relative water content (RWC), dry mass of leaf, and antioxidants such as ascorbate and glutathione in the tested tea clones (TV-1, TV-17, and TV-29) was minimized by zinc sulfate (ZnSO4) treatment before water withholding for 7 days. Increase in phenolic content with decrease in hydrogen peroxide (H2O2) and lipid peroxidation and differential activities of enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), polyphenol peroxidase (PPO), glutathione reductase (GR), and ascorbate peroxidase (APX) with concomitant increased Zn uptake in leaf suggested Zn modulates drought-mediated biochemical damages in tea plant. © 2013 American Chemical Society.


Tewari S.,Karimganj College | Bhattacharjee A.,National Institute of Technology Silchar
Pramana - Journal of Physics | Year: 2011

Thin films of zinc oxide (ZnO) were deposited on cleaned glass substrates by chemical spray pyrolysis technique using Zn(CH3COO)2 as precursor solution. Also, aluminium-doped thin films of ZnO were prepared by using AlCl3 as doping solution for aluminium. The dopant concentration [Al/Zn atomic percentage (at%)] was varied from 0 to 1.5 at% in thin films of ZnO prepared in different depositions. Structural characterization of the deposited films was performed with X-ray diffraction (XRD) studies. It confirmed that all the films were of zinc oxide having polycrystalline nature and possessing typical hexagonal wurtzite structure with crystallite size varying between 100.7 and 268.6 nm. The films exhibited changes in relative intensities and crystallite size with changes in the doping concentration of Al. The electrical studies established that 1 at% of Aldoping was the optimum for enhancing electrical conduction in ZnO thin films and beyond that the distortion caused in the lattice lowered the conductivity. The films also exhibited distinct changes in their optical properties at different doping concentrations, including a blue shift and slight widening of bandgap with increasing Al dopant concentration. © Indian Academy of Sciences.


Datta Sarkar S.,Karimganj College | Choudhury B.,N.I.T.
Acta Physica Polonica A | Year: 2010

The compounds 5-pentyl-2-(4′-cyanophenyl) pyrimidine [CM 7035] and 4-n-butyl-4'-ethoxytolan [PTP4O2] and mixtures of different mole fractions of them show nematic phase with supercooling effect. From the phase diagram the equimolar mixture is found to be the eutectic mixture. Temperature variation of the density and refractive indices (no,ne) of the pure compounds and their eutectic mixture have been reported here. The density and birefringence values of the eutectic mixture are found to be less than that of pure compounds. However the average refractive index values of eutectic mixture almost coincide with those of CM 7035 which are much less than those of PTP4O2. The refractive indices and density values have been analyzed to obtain the orientational order parameters. Experimental order parameter values of the pure compounds and the eutectic mixture are compared with theoretical Maier-Saupe values. The possible reasons for disagreement between theoretical and experimental values for the pure compounds are discussed. The agreement between theoretical and experimental order parameters are fairly good for the eutectic mixture.


Singh V.K.,National Institute of Technology Rourkela | Banerjee I.,National Institute of Technology Rourkela | Agarwal T.,National Institute of Technology Rourkela | Pramanik K.,National Institute of Technology Rourkela | And 2 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2014

Bigels are novel semi-solid formulations which have been drawing attention of many research scientists due to their numerous advantages over the conventional gels. The objective of this study was to develop and characterize novel bigels by mixing guar gum hydrogel and sorbitan monostearate-sesame oil based organogel for controlled drug delivery applications. The confocal microscopy suggested the existence of both aqueous and oil phases together as bigel. Micro-scale deformation (viscometric) analysis in conjugation with macro-scale deformation studies suggested shear-thinning and viscoelastic nature of the bigels. Thermal study suggested an increase in thermal stability with the increase in organogel proportion in the bigels. The developed bigels were biocompatible in nature. The in vitro drug release study showed that the release of ciprofloxacin (lipophilic drug) increased with a decrease in the organogel content. Further analysis showed that the drug release from all the bigels followed zero order diffusion kinetics which is desirable for a controlled release system. The drug loaded gels showed good antimicrobial efficiency against Bacillus subtilis. In conclusion, the developed bigels may be tried as matrices for topical drug delivery. © 2014 Elsevier B.V.


Singh V.K.,National Institute of Technology Rourkela | Anis A.,King Saud University | Banerjee I.,National Institute of Technology Rourkela | Pramanik K.,National Institute of Technology Rourkela | And 2 more authors.
Materials Science and Engineering C | Year: 2014

The current study reports the development of bigels using sorbitan monostearate-sesame oil organogel and carbopol 934 hydrogel. The microstructures and physicochemical properties were investigated by microscopy, viscosity measurement, mechanical analysis and differential scanning calorimetry analysis. Fluorescence microscopy confirmed the formation of oil-in-water type of emulsion gel. There was an increase in the strength of the bigels as the proportion of the organogel was increased in the bigels. The developed bigels showed shear-thinning flow behavior. The stress relaxation study suggested viscoelastic nature of the bigels. The developed bigels were biocompatible. Metronidazole, drug of choice for the treatment of bacterial vaginosis, loaded bigels showed diffusion-mediated drug release. The drug loaded gels showed good antimicrobial efficiency against Escherichia coli. In gist, the developed bigels may be used as delivery vehicles for the vaginal delivery of the drugs. © 2014 Published by Elsevier B.V.


Sarkar S.D.,Karimganj College | Choudhury B.,National Institute of Technology Silchar
Molecular Crystals and Liquid Crystals | Year: 2011

We report here temperature variation of refractive indices, dielectric permittivities and densities of a nematogenic tolan compound (4-n-butyl-4'-ethoxytolan). The sample exhibits high birefringence. The refractive indices and density values have been analyzed to obtain the orientational order parameters. Experimental order parameters are compared with theoretical Maier-Saupe values. The variation of dielectric permittivities with temperature has been determined for the sample at frequency 1kHz. The sample shows very low dielectric anisotropy. The molecular dipole moment and the angle of inclination of the molecular dipole moment with the director are also calculated. Copyright © Taylor & Francis Group, LLC.


Pal K.,National Institute of Technology Rourkela | Singh V.K.,National Institute of Technology Rourkela | Anis A.,King Saud University | Thakur G.,Manipal University India | Bhattacharya M.K.,Karimganj College
Polymer - Plastics Technology and Engineering | Year: 2013

Hydrogels have evolved over the last decade as materials of choice in varied biomedical applications. This is associated with the inherent biocompatible nature of the hydrogels. The modulation of the properties of the hydrogels is easily possible due to the availability of polymers of varied chemistry and physical properties. This review discusses the pharmaceutical aspects of the controlled release of bioactive agents from hydrogel-based formulations. © 2013 Copyright Taylor and Francis Group, LLC.

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