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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.


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.


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.


Sharma R.,Arts and Commerce Girls College | Bisen D.P.,Pandit Ravishankar Shukla University | Dhoble S.J.,Rashtrasant Tukadoji Maharaj Nagpur University | Brahme N.,Pandit Ravishankar Shukla University | Chandra B.P.,Disha Institute of Management and Technology
Journal of Luminescence | Year: 2011

This paper reports the synthesis of ZnS:Mn nanocrystals by the chemical route in which mercaptoethanol was used as the capping agent. The particle size of such nanocrystals was measured using XRD and TEM patterns and was found to be in between 3and 5 nm. It was found that the peak position of TL glow curve and the TL intensity of ZnS:Mn nanoparticles increases as the particle size is decreased. The isothermal decay technique is used to determine the trap-depth. The stability of the charge carriers in the traps increase with the decrease in size of the nanoparticles. The higher stability may be attributed to the higher surface/volume ratio and also to the increase in the trap-depth with decreasing particle size. When a ZnS:Mn nanocrystal is deformed the peak intensity I m increases linearly with the increasing height of the load. After Im, initially the ML intensity decreases at a fast rate, and later on it decreases at a slow rate. The ML in ZnS:Mn nanocrystals can be understood on the basis of the piezoelectrically induced electron detrapping model. © 2011 Elsevier B.V.


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.


Sahu V.,Pandit Ravishankar Shukla University | Brahme N.,Pandit Ravishankar Shukla University | Bisen D.P.,Pandit Ravishankar Shukla University | Sharma R.,Arts and Commerce Girls College
Optoelectronics and Advanced Materials, Rapid Communications | Year: 2010

The effect of temperature on the lyoluminescence (LL) of divalent impurity doped potassium chloride has been reported. When gamma irradiated doped potassium chloride are dissolved in heated water, the LL intensity initially increases with time, attains a maximum value, then it decreases and finally disappears. The peak Im of LL intensity versus time curve initially increases with temperature attains an optimum value at a particular temperature and then it decreases with further increase in temperature. However, the total intensity IT and time tm corresponding to the peak of LL intensity versus time curves decrease with increasing temperature of the solution. The peak intensity Im is optimum at a particular temperature because of the competition between increase in rate of dissolution of KCl with temperature and decrease in efficiency η and density of F-centres with temperature. The value of time tm decreases with increasing temperature of the solution because of the increasing rate constant for the recombination of hydrated electrons with holes. The efficiency η and nF decrease with temperature and therefore, the total intensity IT decreases with increasing temperature of the solvent. The decay time T depends inversely on the rate of dissolution α of solute in the solvent. Since α increase with increasing temperature of the solution, T decreases with increasing temperature of the solution. A plausible explanation for the experimental results is given.


PubMed | Amity University, Pandit Ravishankar Shukla University and Arts and Commerce Girls College
Type: Journal Article | Journal: Luminescence : the journal of biological and chemical luminescence | Year: 2016

Ce(3+)-doped calcium aluminosilicate phosphor was prepared by a combustion-assisted method at an initiating temperature of 600C. Structural characterization was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The absorption spectra of Ca2Al2SiO7:Ce(3+) showed an absorption edge at 230 nm. The optical characterization of Ca2Al2SiO7:Ce(3+) phosphor was investigated in a fracto-mechanoluminescence (FML) and thermoluminescence (TL) study. The peak of ML intensity increased as the height of impact of the moving piston increased. The TL intensity of Ca2Al2SiO7:Ce(3+) was recorded for different exposure times of UV and -irradiation and it was observed that TL intensity was maximum for a UV irradiation time of 30 min and for a -dose of 1180 Gy. The TL intensity had three peaks for UV irradiation at temperatures 82C, 125C and 203C. Also the TL intensity had a single peak at 152C for -irradiation. The TL and ML emission spectra of Ca2Al2SiO7:Ce(3+) phosphor showed maximum emission at 400 nm. The possible mechanisms involved in the TL and ML processes of the Ca2Al2SiO7:Ce(3+) phosphor are also explained.


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.


Sharma R.,Arts and Commerce Girls College
Luminescence | Year: 2012

Cadmium sulphide nanoparticles were grown using a wet chemical method, by dissolving the reactants, cadmium chloride and sodium sulphide in water, in the presence of mercaptoethanol (ME), which was used as a capping agent. Manganese chloride was used to dope the nanoparticles. It was found that the particle size varied with different concentrations of ME. At higher concentrations of ME, smaller sized nanoparticles were synthesized. This method also reveals the high stability of nanoparticles in water. Nanoparticle properties were investigated using UV-vis absorption, photoluminescence spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The particle sizes were measured by the XRD technique, SEM and optical absorption spectra and were in the range 2-6 nm. Copyright © 2011 John Wiley & Sons, Ltd.


Sharma K.,Arts and Commerce Girls College
Oriental Journal of Chemistry | Year: 2011

The importance of Phosphate solubilization by microorganisms is well established in agriculture and dephosphorization of mineral ores. Ten species of Penicillium inhabiting the soils of Pachmarhi hills (1108-1287m above msl) have been tested for their capacity of Phosphate solubilization using two samples of rock Phosphate and three of iron ores. The rock phosphate was solubilized upto 61.6% gm biomass in 10 days at 30æ%c and the Phosphorus content of the iron ores was reduced upto 47.6% gm biomass. The fungi P.restrictum, P.rugulosum, P.citrinum, P.islandicum and P.melinii utilized the solubilized Phosphate for their growth and liberated the Phosphorus in cultural broths. They appeared promising candidates as biofertilizer in agriculture and in metallurgical processing for dephosphorization of iron ore. It was also evidenced that Phosphate solubilization potential of these Penicillia was related with their microhabitate where soluble Phosphate is scarcely available.

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