Bangabasi Morning College

Kolkata, India

Bangabasi Morning College

Kolkata, India
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Zecca A.,University of Trento | Chiari L.,University of Trento | Chiari L.,Flinders University | Sarkar A.,Bangabasi Morning College | And 2 more authors.
New Journal of Physics | Year: 2011

We report our results on the experimental total cross sections (TCSs) for positron scattering from the isoelectronic molecules N2, CO and C2H2. Where possible, for each species, comparison is made between the present results and those from earlier measurements and calculations. The agreement between the present and earlier experimental results, within the overall uncertainties on the data, is typically satisfactory for energies greater than about 8 eV, but is only marginal at lower positron impact energies. While N2, CO and C2H2 possess 14 electrons each, we find significant differences in the magnitudes of their respective TCSs and subtle differences in the energy dependence of these TCSs. These details are discussed in depth in this paper. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Zecca A.,University of Trento | Chiari L.,University of Trento | Sarkar A.,Bangabasi Morning College | Chattopadhyay S.,Taki Government College | Brunger M.J.,Flinders University
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2010

We report recipes for the successful conditioning of tungsten and nickel moderators, for application in positron-scattering experiments. In addition, the comparative performance of those moderators, as a result of these procedures, is assessed. © 2009 Elsevier B.V. All rights reserved.

Mahato P.,Narasinha Dutt College | Bhattacharya P.,Bangabasi Morning College
Modern Physics Letters A | Year: 2011

In the torsion ⊗ curvature approach of gravity Chern-Simons modification has been considered here. It has been found that Chern-Simons contribution to the Bianchi identity cancels from that of the scalar field part. But "homogeneity and isotropy" consideration of present day cosmology is a consequence of the "strong equivalence principle" and vice versa. © 2011 World Scientific Publishing Company.

Zecca A.,University of Trento | Chiari L.,University of Trento | Chiari L.,Flinders University | Trainotti E.,University of Trento | And 7 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2012

We report on measurements of total cross sections for positron scattering from the fundamental organic molecule methane (CH 4). The energy range of these measurements was 0.1-50 eV, whereas the energy resolution was ∼100 meV when our Ni moderator was used and ∼260 meV when the W moderator was employed. To assist us in interpreting these data, Schwinger multichannel calculations were performed at both static and static plus polarization levels of approximation for elastic positron scattering from 0.001 to 10 eV. These calculations are found to be in quite good qualitative agreement with our measured data, and they clearly educe the crucial role played by the target polarization in the low energy positron-CH 4 scattering dynamics. © 2012 American Physical Society.

Neogi S.K.,University of Calcutta | Chattopadhyay S.,University of Calcutta | Chattopadhyay S.,Calcutta Institute of Engineering and Management | Banerjee A.,University of Calcutta | And 3 more authors.
Journal of Physics Condensed Matter | Year: 2011

The present work aims to study the effect of ion irradiation on structural and electrical properties and their correlation with the defects in the Zn 1 - xMnxO-type system. Zn1 - xMnxO (x = 0.02, 0.04) samples have been synthesized by the solid-state reaction method and have been irradiated with 50MeV Li3+ ions. The concomitant changes have been probed by x-ray diffraction (XRD), temperature-dependent electrical resistivity and positron annihilation lifetime (PAL) spectroscopy. The XRD result shows a single-phase wurtzite structure for Zn 0.98Mn0.02O, whereas for the Zn0.96Mn 0.04O sample an impurity phase has been found, apart from the usual peaks of ZnO. Ion irradiation removes this impurity peak. The grain size of the samples is found to be uniform. For Zn0.98Mn0.02O, the observed sharp decrease in room temperature resistivity (ρRT) with irradiation is consistent with the lowering of the full width at half maximum of the XRD peaks. However, for Zn0.96Mn0.04O, ρRT decreases for the initial fluence but increases for a further increase in fluence. All the irradiated Zn0.98Mn0.02O samples show a metal-semiconductor transition in temperature-dependent resistivity measurements at low temperature. But all the irradiated Zn 0.96Mn0.04O samples show a semiconducting nature in the whole range of temperatures. Results of room temperature resistivity, XRD and PAL measurements are consistent with each other. © 2011 IOP Publishing Ltd.

Sanyal D.,Variable Energy Cyclotron Center | Chakrabarti M.,University of Calcutta | Nath P.,University of Calcutta | Sarkar A.,Bangabasi Morning College | And 2 more authors.
Journal of Physics D: Applied Physics | Year: 2014

Room temperature ferromagnetic ordering has been observed in a rutile TiO2 polycrystalline sample after 4 MeV Ar5+ ion irradiation. The sheet resistance of the irradiated sample decreases from 107 to 3 × 103 Ω cm-2. Ab initio calculation in the density-functional theory indicates that both oxygen vacancy (VO) and titanium vacancy (VTi) can lead to ferromagnetism. However, the drastic lowering of resistance and change of colour (from white to black) indicate the formation of VO. Experimental results along with the theoretical calculation suggest that presence of V O in the irradiated sample plays the main role in inducing ferromagnetism. © 2014 IOP Publishing Ltd.

Sarkar A.,Bangabasi Morning College | Chakrabarti M.,University of Calcutta | Ray S.K.,Indian Institute of Technology Kharagpur | Bhowmick D.,Variable Energy Cyclotron Center | Sanyal D.,Variable Energy Cyclotron Center
Journal of Physics Condensed Matter | Year: 2011

The room temperature positron annihilation lifetime for single crystalline ZnO has been measured as 164 ± 1ps. The single component lifetime value is very close to but higher than the theoretically predicted value of ∼ 154 ps. Photoluminescence study (at 10K) indicates the presence of hydrogen and other defects, mainly acceptor related, in the crystal. Defects related to a lower open volume than zinc vacancies, presumably a complex with two hydrogen atoms, are the major trapping sites in the sample. The bulk positron lifetime in ZnO is expected to be a little less than 164ps. © 2011 IOP Publishing Ltd.

Chattopadhyay S.,University of Calcutta | Neogi S.K.,University of Calcutta | Sarkar A.,Bangabasi Morning College | Mukadam M.D.,Bhabha Atomic Research Center | And 3 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2011

Single phase Mn doped (2 at%) ZnO samples have been synthesized by the solid-state reaction technique. Before the final sintering at 500 °C, the mixed powders have been milled for different milling periods (6, 24, 48 and 96 h). The grain sizes of the samples are very close to each other (∼32±4 nm). However, the defective state of the samples is different from each other as manifested from the variation of magnetic properties and electrical resistivity with milling time. All the samples have been found to be ferromagnetic with clear hysteresis loops at room temperature. The maximum value for saturation magnetization (0.11 μB/Mn atom) was achieved for 96 h milled sample. Electrical resistivity has been found to increase with increase in milling time. The most resistive sample bears the largest saturation magnetization. Variation of average positron lifetime with milling time bears a close similarity with that of the saturation magnetization. This indicates the key role played by open volume vacancy defects, presumably zinc vacancies near grain surfaces, in inducing ferromagnetic order in Mn doped ZnO. To attain optimum defect configuration favorable for ferromagnetism in this kind of samples proper choice of milling period and annealing conditions is required. © 2010 Elsevier B.V.

Sinha Babu S.,Bangabasi Morning College | Datta S.K.,University of Burdwan
Environment, Development and Sustainability | Year: 2015

The link between economic, social, and environmental indicators is often complex and requires a detailed analysis for its understanding. The economy is dependent on the society and the environment, while the very existence of human race and society depends on and within the environment. Thus, these three entities are intricately interconnected, and it is therefore important to understand that any individual group of economic, social or environmental indicators must always be interpreted in connection with the other two groups, since only in this way, an integrated view of the functioning of an economy can be ensured. For the system to be sustainable, the different forces that act on this particular system of interaction must be in balance. Hence, a detailed analysis of selected economic, social, and environmental aspects of development and their linkages is a matter of utmost significance. The objective of this study is to identify an endogenously integrated relationship where economic factor such as gross domestic product per capita influences both qualitative and quantitative factors in social and environmental dimensions and vice versa and to focus on possible correlation between a set of ambient environmental aspects and a set of socio-economic dimensions that influence human well-being and sustainability. The results of the empirical analysis emphasise the fact that there exists bi-directional relationship between different developmental and environmental aspects in the developing countries. The study further argues that without consideration of depreciation/depletion charges for the environmental capital, this relation will not reflect the true interdependence. © 2014, Springer Science+Business Media Dordrecht.

Saha S.,Prantapalli High School | Saha S.,Bangabasi Morning College | Ray S.,University of Calcutta
Clean - Soil, Air, Water | Year: 2014

Estuarine edible crab, Scylla serrata (Crustacea: Decapoda) occupy diverse habitats and their strategy of survival is correlated to multidimensional immune responses and its inhabiting in bio-unsafe environment is under constant threat of physiological stress caused by diverse xenobiotics including arsenic. Experimental crabs, exposed to 1-3ppm of sodium arsenite for a maximum period of 30 days in controlled laboratory condition indicated that arsenic as cytotoxicant as well as immunotoxicant causes damage and an alteration in cytotoxic status and antioxidant status in hemocytes. In this study, we investigated the intrahemocytic production of phenoloxidase, super oxide anion, nitric oxide, and its subsequent scavenging under the exposure of sodium arsenite. Arsenic induced variations in generation of cytotoxic molecules as well as antioxidant enzymes activity in intrahemocyte is indicative to possible immune-alteration of the animal distributed in bio-unsafe environment. Arsenic induced impairment of immune response may initiate an opportunistic growth of microbes in crab. Chronic exposure of S. serrata to arsenic may lead to decline of this economically important endemic species in Sundarbans Biosphere Reserve of West Bengal. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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