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Kolkata, India

Halder J.,Vidyasagar College
Rasayan Journal of Chemistry | Year: 2012

Sodium bromide in presence of 1(M) HCl with common household bleach generates bromine in situ and undergoes aromatic electrophilic substitution reaction selectively in good yield in a mild reaction condition. This is a very cost effective, elegant, water based method for activated aromatic bromination reported for the first time. © 2012 RASĀYAN. All rights reserved.

Dasgupta R.,Vidyasagar College
Journal of the Geological Society of India | Year: 2013

Morphological studies of shore platforms have focused on elements like width, gradient and elevation, while mostly ignoring the surface roughness as a morphometric attribute. This paper uses the Roughness-length method to show how the Fractal Dimension of a shore platform profile can be obtained. The higher the value of the fractal dimension, the higher is the roughness of the platform. The studied profile is situated in Houghton Bay on the south coast of Wellington, New Zealand. The fractal dimension of the profile under consideration was found to be 1.314. However, one profile is not sufficient to provide information about the surface roughness of a shore platform. Therefore, a number of profiles should be taken to have an idea about surface roughness. © 2013 Geological Society of India.

Mukherjee D.,Sudan University of Science and Technology | Roy S.G.,Indian Institute of Chemical Technology | Bandyopadhyay A.,Indian Institute of Chemical Technology | Chattopadhyay A.,Vidyasagar College | And 5 more authors.
Journal of Pineal Research | Year: 2010

The present study was undertaken to explore the protective effect of melatonin against isoproterenol bitartrate (ISO)-induced myocardial injury in rat. Treatment of rats with ISO increased the level of lipid peroxidation products and decreased the reduced glutathione levels in cardiac tissue indicating that this synthetic catecholamine induces oxidative damage following oxidative stress. Pretreatment of ISO-injected rats with melatonin at a dose of 10 mg/kg body weight, i.p. prevented these changes. Additionally, melatonin also restored the activities and the levels of antioxidant enzymes which were found to be altered by ISO treatment. Treatment of rats with ISO resulted into an increased generation of hydroxyl radicals with melatonin pretreatment significantly reducing their production. Finally, treatment of rats with ISO caused a lowering of systolic pressure with reduced cardiac output and diastolic dysfunction whereas melatonin pretreatment significantly restored many of these parameters to normal. The findings document melatonin's ability to provide cardio protection at a low pharmacological dose. Melatonin has virtually no toxicity which raises the possibility of this indole being a therapeutic treatment for ischemic heart disease. © 2010 John Wiley & Sons A/S.

Ghosh B.,Jadavpur University | Banerjee S.,Vidyasagar College
Journal of Plasma Physics | Year: 2015

Nonlinear amplitude modulation of ion-acoustic waves (IAWs) in a fully relativistic unmagnetized two-fluid plasma has been theoretically studied by using complete set of fully relativistic dynamic equations. To describe the nonlinear evolution of the wave envelope a nonlinear Schrödinger (NLS) equation is derived by using standard multiple scale perturbation technique. Using this equation it is shown that the wave becomes modulationally unstable as the wavenumber exceeds certain critical value. This critical wavenumber is found to decrease with increase in relativistic effect. The instability growth rate has also been calculated numerically for different values of plasma drift velocity. The growth rate is shown to decrease with increase in the relativistic effect. © Cambridge University Press 2015.

Ghosh B.,Jadavpur University | Banerjee S.,Vidyasagar College
Indian Journal of Physics | Year: 2015

Using Sagdeev potential technique, ion-acoustic solitary waves have been theoretically studied in collisionless unmagnetized plasma consisting of nonthermal electrons, nonthermal positrons and warm drifting positive ions. Ion-acoustic solitary wave solutions have been obtained and its profiles have been numerically analyzed with respect to plasma parameters. The nonthermal parameters and temperatures are shown to play significant role on the formation and nature of solitary waves. It is shown that the nature, amplitude and width of lower- and higher-order solitons depend sensitively on these plasma parameters. The dependence of Sagdeev potential profile on different plasma parameters has also been examined. We have found that stronger nonthermality leads to shorter and wider solitons. © 2015, Indian Association for the Cultivation of Science.

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