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Chandra B.P.,Ashoka Institute of Technology and Management | Tiwari C.S.,Government Postgaduate College | Sharma R.,Arts and Commerce Girls College
Luminescence | Year: 2013

When an γ-irradiated Dy-, Tm-, Sm- or Mn-doped CaSO4 crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post-deformation region of the crystals. In this study, intensities Im1 and Im2 corresponding to first and second ML peaks, respectively, increased linearly with an impact velocity v0 of the piston used to deform the crystals, and times tm1 and t m2 corresponding to the first and second ML peaks, respectively, decreased with impact velocity. Total ML intensity initially increased with impact velocity and then reached a saturation value for higher values of impact velocity. ML intensity increased with increasing γ-doses and size of crystals. Results showed that the electric field produced as a result of charging of newly-created surfaces caused tunneling of electrons to the valence band of the hole-trapping centres. The free holes generated moved in the valence band and their subsequent recombination with electron trapping centres released energy, thereby resulting in excitation of luminescent centres. Copyright © 2012 John Wiley & Sons, Ltd. Source


Sharma K.,Arts and Commerce Girls College
International Journal of Soil Science | Year: 2011

This review study focuses on mould biodiversity of certain airborne, soilborne and leaf surface mycoflora. Airborne mycoflora can be considered under outdoor and indoor environment, i.e., cold storage, Raipur City, Dwelling houses, Ocimum sanctum field whereas soilborne mycofloral study includes Darjeeling tea garden and Yumthang Valley and leaf surface mycoflora of Ocimum sanctum and effects of exudates on spore germination also studied. The studies revealed rich biodiversity of moulds in the different environment. Further fluctuation in air and soil fungal flora was observed as influenced by meteorogical parameters. Cladosporium, Penicillium and Aspergillus were found to be dominant in most of the aeromycoflora, whereas Aspergillus niger found to be dominant in soil. © 2011 Academic Journals Inc. Source


Biswas J.,National Cave Research and Protection Organization | Sharma K.,National Cave Research and Protection Organization | Sharma K.,Arts and Commerce Girls College | Harris K.K.,National Cave Research and Protection Organization | And 2 more authors.
Iranian Journal of Microbiology | Year: 2013

Background and Objectives: In the last few decades, losses of our cultural heritage due to biodeteriorationare beinghighly recognized. From museum objects to rock monuments, the microbial biodeterioration agents are found to be the most destructive. Possibilities for proper preservative measure(s) are always more when it is only a monument, statue, museum article, or pre-historic art in any small subterranean cave. Nevertheless, preservation/protection of the footprints occupying a big area, lying scattered in a very negligible manner requires safeguard against several deterioration factors; right from various physical, chemical and biological agents which are indeed interrelated to each other. Materials and Methods: In the present study, some microbial communities possibly responsible for deteriorating the rocks of Kabra-pahad, where the most famous pre-historic rock paints of India prevail have been identified. The diversity of fungi and bacteria present in the stone crust of the infected areas has been studied by employing standard laboratory methods. Results:The cultivated cultures confirmed total fifteen fungal species, among which Aspergillus group were the most dominant. Among bacteria, total 80 numbers of colonies were observed that dominated by two major groups; Micrococcus. spp and Staphylococcus spp. Conclusion: The pre-historic footprint in the form of rock paints in Kabra-pahad of district Raigarh, Chhattisgarh, India is lying in a very deteriorated manner. In the present study, we have tried to identify few major deteriorating factors that are responsible for such degradation of our existing pre-historic footprints. Source


Sharma R.,Arts and Commerce Girls College | Bisen D.P.,Pandit Ravishankar Shukla University
E-Journal of Chemistry | Year: 2010

The present paper reports the synthesis and characterization of luminescent nanocrystals of manganese doped zinc sulphide. Nanocrystals of zinc sulphide were prepared by chemical precipitation method using the solution of zinc chloride, sodium sulphide, manganese chloride and mercaptoethanol was used as the capping agent. It was found that change in the molar concentration changes the particle size. The particle size of such nanocrystals was measured using XRD pattern and it is found to be in between 3 nm - 5 nm. The blue-shift in absorption spectra was found with reducing size of the nanoparticles. Source


Tiwari G.,Pandit Ravishankar Shukla University | Brahme N.,Pandit Ravishankar Shukla University | Bisen D.P.,Pandit Ravishankar Shukla University | Sao S.K.,Pandit Ravishankar Shukla University | Sharma R.,Arts and Commerce Girls College
Physics Procedia | Year: 2015

Rare earth activated, white light emitting Ca2Al2SiO7: Ce3+, Tb3+ phosphor was synthesized by combustion method at initiating temperature of 600 °C, using urea as a reducer. X-Ray diffraction, absorption spectra, thermoluminescence(TL) and mechanoluminescence (ML) were studied. The particle size was found to be 50.85 nm. The absorption spectra shows that the absorption edge is at λ = 240 nm. Two peaks were observed in the plot of time vs ML intensity. ML intensity increases with increasing droping height of the piston. The TL intensity was increased with increasing UV exposure time indicating the increase in concentration of trapped carriers with UV exposure. The TL emission spectra was found at 400nm (UV-violet band) and 540nm (green band). © 2015 The Authors. Published by Elsevier B.V. Source

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