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North Guwāhāti, India

Ghosh D.,Jadavpur University | Deb A.,Jadavpur University | Pal S.,Kanchrapara College | Mondal M.,S A Jaipuria College
Physica Scripta

In this paper, a detailed study of the chaotic behavior of compound hadrons (pions plus protons) in π--AgBr interactions at 350 GeV c -1 has been performed with the help of the parameter 'entropy index' μq, which is a measure of the chaotic behavior in multipion production processes. This index describes the event-to-event fluctuation of factorial moments that measures the spatial fluctuation of multiplicity distribution. The analysis reveals a large value for the entropy index signifying the chaotic behavior of the produced compound hadrons in high-energy hadron-nucleus interactions. It was been observed that the multipion production process becomes less chaotic with increasing average multiplicity of the final states. The study has been further extended to pions, and the corresponding results are compared. © 2010 The Royal Swedish Academy of Sciences. Source

Chakraborty S.,French National Center for Scientific Research | Chakraborty S.,Kanchrapara College | Bardelli F.,French National Center for Scientific Research | Bardelli F.,University of Turin | And 6 more authors.
Chemical Geology

Biotite is a constituent Fe-bearing mineral of Delta subsoils in India and Bangladesh and has been hypothesized as a primary source of arsenic (As). The adsorption behavior of As onto structural Fe(II, III)-bearing biotite fractions (<50μm) was investigated in the pH range of 4-8 under a CO2-free, anoxic condition (O2<1ppmv) using X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS). The batch experiments indicate that As adsorption is strongly pH dependent and that As(V) adsorbs more efficiently than As(III). X-ray Absorption Near-Edge Structure (XANES) spectra show no oxidation or reduction of As by biotite after reaction with As(III) or As(V) solutions for 3days. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopic results suggest that As(III) forms bidentate mononuclear edge-sharing (2E) and bidentate binuclear corner-sharing (2C) surface complexes at pH 7.7 as indicated by average As-Fe bond distances at 3.00±0.02Å and 3.37±0.03Å respectively. The surface speciation retrieved by XPS does not provide any evidence of reduction of As(V) on biotite after 30days further confirming the thermodynamic prediction and the XANES results. This study has therefore significant environmental implications for As contaminated areas, where biotite retards the release of As into reducing groundwater. The changes in soil redox conditions and weathering of biotite may likely contribute to the occurrence of high As in groundwater. © 2010 Elsevier B.V. Source

Saha I.,Presidency University of India | Saha I.,Sripat Singh College | Gupta K.,Presidency University of India | Chakraborty S.,Kanchrapara College | And 2 more authors.
Journal of Industrial and Engineering Chemistry

This study investigates the adsorption of As(III) on β-cyclodextrin modified hydrous ferric oxide (HCC). This is characterized by XRD, FESEM, AFM, XPS, BET, surface site concentration and FTIR. The modification of hydrous ferric oxide (HFO) surface by β-cyclodextrin provides ample OH groups which in turn increase As(III) adsorption on HCC compared to HFO. The adsorption remains almost constant in pH range 3-8 which decreases at higher pH (>8) and followed monolayer and pseudo first order kinetics. It is spontaneous at 303. K with increasing entropy and decreasing enthalpy. Thus HCC is found to be more efficient adsorbent than HFO. © 2013 The Korean Society of Industrial and Engineering Chemistry. Source

Bhattacharya P.,Kalyani University | Bhattacharya P.,Kanchrapara College | Samal A.C.,Kalyani University | Majumdar J.,Kalyani University | And 2 more authors.
Journal of Hazardous Materials

Rice is an efficient accumulator of arsenic and thus irrigation with arsenic-contaminated groundwater and soil may induce human health hazard via water-soil-plant-human pathway. A greenhouse pot experiment was conducted on three high yielding, one hybrid and four local rice varieties to investigate the uptake, distribution and phytotoxicity of arsenic in rice plant. 5, 10, 20, 30 and 40mgkg-1 dry weights arsenic dosing was applied in pot soil and the results were compared with the control samples. All the studied high yielding and hybrid varieties (Ratna, IET 4094, IR 50 and Gangakaveri) were found to be higher accumulator of arsenic as compared to all but one local rice variety, Kerala Sundari. In these five rice varieties accumulation of arsenic in grain exceeded the WHO permissible limit (1.0mgkg-1) at 20mgkg-1 arsenic dosing. Irrespective of variety, arsenic accumulation in different parts of rice plant was found to increase with increasing arsenic doses, but not at the same rate. A consistent negative correlation was established between soil arsenic and chlorophyll contents while carbohydrate accumulation depicted consistent positive correlation with increasing arsenic toxicity in rice plant. © 2012 Elsevier B.V. Source

Ghosh D.,Jadavpur University | Deb A.,Jadavpur University | Mondal M.,Sa Jaipuria College | Mondal A.,Institute of Information Technology | Pal S.,Kanchrapara College
Pramana - Journal of Physics

Event-to-event fluctuation pattern of pions produced by proton and pion beams is studied in terms of the newly defined erraticity measures x(p, q), x'q andμq' proposed by Cao and Hwa. The analysis reveals the erratic behaviour of the produced pions signifying the chaotic multiparticle production in high-energy hadron-nucleus interactions (π--AgBr interactions at 350 GeV/c and p-AgBr interactions at 400 GeV/c). However, the chaoticity does not depend on whether the projectile is proton or pion. The results are compared with the results of the VENUS-generated data for the above interactions which suggests that VENUS event generator is unable to reproduce the event-to-event fluctuations of spatial patterns of final states. A comparative study of p-AgBr interactions and p-p collisions at 400 GeV/c from NA27, with the help of a quantitative parameter for the assessment of pion fluctuation, indicates conclusively that particle production process is more chaotic for hadron-nucleus interactions than for hadron-hadron interactions. © Indian Academy of Sciences. Source

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