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Biswas I.,Raja Rammohun Roy Mahavidyalaya | Mukherjee A.,University of Burdwan
Acta Botanica Hungarica

This pharmacognostic study deals with the leaf-anatomy of Nyctanthes arbor-tristis L., an Indian plant, used in indigenous medicine throughout India from time immemorial. Features like anomocytic stomata, cuticular striations on subsidiary cells, occasional oval or flask shaped epidermal cells, peltate quadripartite glandular trichomes, non-glandular trichomes with smooth or rough surface (spiculate or waxy flaked) and some round bluish bodies appear to be characteristic for the leaves of this species. Fluorescence characteristics of the leaf dust under different chemical treatments using UV and ordinary light have also been recorded for pharmacognostic standardisation. Source

Dutta B.,Sammilani Mahavidyalaya | De R.,Raja Rammohun Roy Mahavidyalaya | Chowdhury J.,Sammilani Mahavidyalaya
Indian Journal of Physics

Origin of the conformational barrier of isobutyl cyanide (IBCN) molecule has been investigated. Ab initio and density functional theory calculations predict the existence of two minima on the potential energy surface corresponding to trans-gauche (TG) and gauche-gauche (GG) rotameric forms and one enantiomeric gauche-trans (GT) form of the IBCN molecule. The barrier heights between TG and GG, TG and GT are estimated as 5.7 and 3.78 kcal/mol respectively. Origin of conformational barrier of molecule has been studied by partial relaxations and with the aid of nuclear virial and natural bond orbital analysis technique. The relaxations of C1-C2 bond and C1-C2-C3 and C1-C2-C 4 bond angles are estimated to play a pivotal role for conformational barrier of the molecule. © 2013 Indian Association for the Cultivation of Science. Source

Dutta B.,Sammilani Mahavidyalaya | De R.,Raja Rammohun Roy Mahavidyalaya | Chowdhury J.,Sammilani Mahavidyalaya
Chemical Physics

The ground state prototropic tautomerism of 4-Methyl 1,2,4-Triazole-3-Thione molecule in solvent water medium has been investigated with the aid of DFT and Car-Parrinello molecular dynamics (CPMD) simulation studies. The CPMD simulations envisage the possibility of proton transfer reactions of the molecule through the solvent water medium. Probable proton transfer pathways have been predicted from the DFT calculations which are substantiated by the natural bond orbital analyses. The evolution and breaking of the concerned bonds of the molecule for different proton transfer reaction pathways are also estimated. © 2015 Elsevier B.V.All rights reserved. Source

Mitra R.,University of Burdwan | Bauri A.K.,Bhabha Atomic Research Center | Banerjee S.,Raja Rammohun Roy Mahavidyalaya | Bhattacharya S.,University of Burdwan
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

The present article reports the role of gold nanoparticles, i.e., AuNp (having diameter ∼2-4 nm), in non-covalent interaction between fullerenes (C60 and C70) and a monoporphyrin (1) in toluene. Both UV-vis and fluorescence measurements reveal considerable reduction in the average value of binding constant (Kav) for the C70-1 system (KC70-1(av) = 19,300 dm3 mol-1) in presence of AuNp, i.e., KC70-1 -AuNp(av) = 13,515 dm3 mol-1 although no such phenomenon is observed in case of C60-1 system, viz., K C60-1(av) = 1445 dm3 mol -1 and KC60-1-AuNp(av) = 1210 dm3 mol-1. DLS study reveals sizeable amount of increase in the particle size of C70-1-AuNp nanocomposite, i.e., ∼105 nm, compared to C60-1-AgNp system, e.g., ∼5.5 nm which gives very good support in favor of decrease in the value of Kav for the former system. SEM study reveals that nanoparticles are dispersed in larger extent in case of C70-1-AuNp system. Time-resolved fluorescence study envisages that deactivation of the excited singlet state of 1 by C70 takes place at a faster rate in comparison to C60 in presence of gold nanoparticles. © 2014 Elsevier B.V. All rights reserved. Source

Absolute values of enthalpy and Gibbs free energy of hydration (h) or solvation (s) of H+ ion, ΔH0(H+)h or s and ΔG0(H+)h or s in aqueous and non-aqueous solvents (methanol, ethanol, npropanol, iso-propanol, n-butanol, t-butanol, ethylene glycol, propylene carbonate, n-methyl formamide, acetone, tetrahydro furan, 1,4-dioxan, acetonitrile) were determined directly using a single standard state [i.e.H2(g) at 1bar and 298.15K]. A comparative study of the methods of Tissandier et al. and the present one has been made. The values -1299.4 kJ mol-1 (-1303.9 kJ mol-1) and K1284.5 kJ mol-1 (K1288.9 kJ mol-1) for the absolute enthalpy [ΔH0 h(H +)] and Gibbs free energy [ΔG0 h(H +)] of hydration determined in the present work have been found to be much lower than the corresponding values K1150.1±0.9 kJ mol-1 and K1104.5±0.3 kJmol-1 determined by Tissandier et al. using cluster-ion solvation data. The values of Tissandier et al. have been acclaimed to be the most accurate values of these quantities by most of the workers. However, the method is based on approximations and assumptions and uses a number of conventional standard states. The calculations use the principle of ionic additivity and Klot's equation which are open to question. The equations, based on the difference between several sets of energy values of different ion-pairs of similar magnitude, have been used. Thus, the method is insensitive and many of the important energy terms characterizing the ions and the structure of the solvents are eliminated. Thus the accuracy of the energy values are not without question. © by Oldenbourg Wissenschaftsverlag, München. Source

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