Banerjee S.,Vidyasagar College |
Ghosh B.,Jadavpur University
Indian Journal of Physics | Year: 2017
To describe the modulational instability of space-charge waves in an n-type compensated semiconductor plasma, a nonlinear Schrödinger equation has been derived by using quantum hydrodynamical model and standard multiple scale perturbation technique. It has been shown that compensation factor (i.e. relative proportion of donor, acceptor and intrinsic carrier concentrations) and quantum diffraction parameter play important role in generating bright and dark envelope solitons within the semiconductor. Instability growth rate is also found to depend sensitively on the compensation factor and quantum diffraction parameter. From the linear dispersion relation it has been found that inclusion of quantum parameter gives rise to two new wave modes of purely quantum origin. Further the effect of compensation factor and quantum diffraction parameter on the linear dispersion characteristics has been analyzed. It has also been found that due to parabolicity of conduction band the group velocity of space-charge wave becomes dependent on compensation factor and quantum diffraction parameter. © 2016, Indian Association for the Cultivation of Science.
Dasgupta R.,Vidyasagar College |
Dasgupta R.,East Calcutta Girls College |
Patel P.P.,Presidency University of India
Geographical Research | Year: 2017
The physical-human dichotomy in geography is long standing, revolving around the topics studied and outlooks adopted by the two groups of geographers. Three reasons are identified for its continuation—the present structure of academic geography, constrained interactions between physical and human geographers, and their publication strategies. Critics suggest that physical and human geography have become divergent strains because the physical environment has been accorded little relevance in human geographic studies, also putting forward the failure of physical geographers to integrate the human influence on physical processes and neglecting space in their studies. Citing examples, this paper argues that physical and human geography influence each other. It also demonstrates that physical geographers have sufficiently considered both space and time, and even space-time, through the concepts of scale and ergodicity. Some measures have been proposed to resuscitate the links between these two branches. These are reconnecting university and school geography, merging departments, teaching courses on geographical philosophies and theory building, engaging in integrative discourses, innovative classroom strategies, joint fieldwork, using geoinformatics, and conducting collaborative research. The paper concludes that physical and human geographers must communicate with each other more and engage in cross-disciplinary studies. Otherwise, they might undermine their responsibilities as geographers and spatial thinkers/analysts. © 2017 Institute of Australian Geographers
Dutta M.,Vidyasagar College |
Ghosh A.K.,University of Calcutta |
Basu A.,University of Calcutta |
Bandyopadhyay D.,University of Calcutta |
Chattopadhyay A.,Vidyasagar College
International Journal of Pharmacy and Pharmaceutical Sciences | Year: 2013
Objective: The present study is aimed at investigating the effect of aqueous bark extract of Terminalia arjuna (TA) against Cu+2-ascorbate induced oxidative stress in goat heart mitochondria in vitro. Methods: Fresh goat heart mitochondria was prepared and oxidative stress was induced in vitro with Copper-ascorbate. Biomarkers of oxidative stress, activities of antioxidant enzymes, Kreb's cycle enzymes and respiratory chain enzymes were determined using standard methods. Results: Treatment of copper-ascorbate treated mitochondria with aqueous bark extract of TA increased reduced glutathione (GSH) levels, reduced lipid peroxidation (LPO) levels and protein carbonyl (PCO) content. It also protects the activities of Mn-superoxide dismutase (Mn-SOD), glutathione reductase (GR) and glutathione peroxidase (GPx) from being altered. Furthermore, it also restores the activities of pyruvate dehydrogenase (PDH), different Kreb's cycle enzymes and mitochondrial respiratory chain enzymes. Moreover, this extract also possesses antioxidant property as established by DPPH radical scavenging activity and reducing power. Conclusion: The present study indicates that the aqueous bark extract of TA is capable of protecting the mitochondria against copper-ascorbate-induced oxidative stress in vitro and hence may be considered for future use as a therapeutic antioxidant intervention.
Mondal S.,Vidyasagar College |
Gupta S.K.,Vidyasagar College
Journal of Parasitic Diseases | Year: 2017
The present paper reports duration of different developmental stages as well as fecundity, longevity, oviposition periods, sex ratio, etc. of Tetranychus sayedi Baker & Pitchard on two medicinal plants, viz. Cryptolepis buchanani Roem & Schult and Justicia adhatoda L. under laboratory condition at 27.5 °C and 65% R.H. during February–March, 2016. The two hosts in which the life cycle was studied form two new records of hosts for this mite. It appears that C. buchanani is better host among the two hosts as because the life cycle (egg to adult) was completed in shorter time, recording high fecundity and longer longevity. © 2017 Indian Society for Parasitology
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
Turkish Journal of Physics | Year: 2016
Using a standard reductive perturbation technique, a nonlinear Schrödinger equation has been derived that describes the nonlinear evolution of ion-acoustic waves in magnetized electron-positron-ion plasma with electrons and positrons following q-nonextensive distribution. It is shown that excitation of both bright and dark envelope solitary structures is possible in the model plasma under consideration. The conditions for the excitation and structure of these envelope solitary waves are shown to depend sensitively on the strength of the external magnetic field, obliqueness of wave propagation relative to the external magnetic field, and other plasma parameters such as the q-nonextensivity of plasma species, positron concentration, and electron-positron temperature ratio. © TÜB̄TAK.
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.
Sengupta D.,Vidyasagar College |
Chowdhury K.D.,Vidyasagar College |
Sarkar A.,Vidyasagar College |
Paul S.,Vidyasagar College |
Sadhukhan G.C.,Vidyasagar College
Biochimica et Biophysica Acta - General Subjects | Year: 2014
Background Diethylnitrosamine (DEN) and carbon tetrachloride (CCl4) have been used as initiator and promoter respectively to establish an animal model for investigating molecular events appear to be involved in development of liver cancer. Use of herbal medicine in therapeutics to avoid the recurrence of hepatocarcinoma has already generated considerable interest among oncologists. In this context studies involving S-allyl-cysteine (SAC) and berberine have come up with promising results. Here we have determined the individual effect of SAC and berberine on the biomolecules associated with DEN + CCl4 induced hepatocarcinoma. Effective therapeutic value of combined treatment has also been estimated. Methods ROS accumulation was analyzed by FACS following DCFDA incubation. Bcl2-Bax and HDAC1-pMdm2 interaction were demonstrated by co-immunoprecipitation. Immunosorbent assay was performed to analyze PP2A and caspase3 activities. MMP was determined cytofluorimetrically by investigating JC-1 fluorescence. AnnexinV binding was demonstrated by labeling the cells with AnV-FITC followed by flow cytometry. Results CytochromeP4502E1 mediated bioactivation of DEN + CCl4 induced Akt dependent pMdm2-HDAC1 interaction that led to p53 deacetylation, probable cause of its degradation. In parallel, oxidative stress dependent Nrf2-HO1 activation increased Bcl2 expression which in turn stimulated cell proliferation. SAC in combination with berberine inhibited Akt mediated cell proliferation. Activation of PP2A as well as inhibition of JNK resulted in induction of apoptosis after 30 days of treatment. Extension of combined treatment reverted tissue physiology towards control. Co-treated group displayed normal tissue structure. Conclusion and general significance SAC and berberine mediated HDAC1/Akt inhibition implicates the efficacy of combined treatment in the amelioration of DEN + CCl4 induced hepatocarcinoma. © 2013 Elsevier B.V.
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.