Patna, India
Patna, India

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Singh S.K.,Montclair State University | Singh S.K.,An College | Ghosh A.K.,An College | Kumar A.,An College | And 6 more authors.
International Journal of Environmental Research | Year: 2014

The extent of groundwater arsenic (As) contamination and associated health-risks were studied in the four villages: Chaukia and Terahrasiya (Vaishali); Mamalkha and Masharu (Bhagalpur) in Bihar, India. Groundwater samples were tested using the standard Silverdiethyledithiocarbamate method at 520nm by Thermo UV-1 spectrophotometer. The As levels in both the districts exceeded the WHO standard of 10μg/L for drinking water with a maximum value of 20μg/L in Vaishali and 143μg/L in Bhagalpur. However, the FAO standard of 100μg/L of As for irrigation water was only exceeded in Bhagalpur. The calculated range of the hazard index (HI) for Vaishali was 0.9 to 10, and for Bhagalpur was 10.40 to 40.47. Both ranges exceed the accepted normal toxic HI of 1.00. The cancer risk was derived as 1-5/1000 people to 5-16/10,000 people in Vaishali, and 7-21/1000 and 5-16/1000 people in Bhagalpur. Prevalence of skin pigmentation was double in Vaishali in comparison to Bhagalpur. The analysis of principal components showed that only two components had a fundamental role in defining variance for cancer risk assessment. A more extensive screening of As contamination of groundwater and a follow-up clinical study are necessary to accurately assess the likelihood of As-related cancers in these districts.

Ghosh A.K.,An College | Bose N.,An College | Kumar R.,An College | German M.,Lehigh University
One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment | Year: 2014

The "water surplus" state of Bihar is faced with the serious problem of arsenic contaminated aquifers whose water is used both for drinking and irrigation purposes. A large number of mitigation strategies are being adopted by the authorities, without obtaining the desired results of clean water supplies to the arsenic affected rural population. The objectives of this study were to identify the gaps in such mitigation techniques and to establish a holistic, innovative technology that is integrated with the socio-economic milieu of the study area. An adsorbent based arsenic removal technology has been tested and is being operated with the community participation. The results revealed a marked reduction in iron and arsenic concentration, effective operational processes and a financially viable clean water production for a community of 25 families, with scope for upscaling this mitigation model. © 2014 Taylor & Francis Group.

Shwetanshumala S.,Birla Institute of Technology | Shwetanshumala S.,An College | Konar S.,Birla Institute of Technology
Physica Scripta | Year: 2011

This paper presents an investigation of the modulation instability (MI) of a broad optical beam in biased centro-symmetric two-photon photorefractive media under undepleted pump approximation. From the evolution equation of the perturbation field, we obtain the expression for growth rate of the sidebands. The occurrence of MI has been found to be constrained by the system parameters. The MI gain function, its maximum value, critical frequency andbandwidth have been evaluated in the unstable region. © 2011 The Royal Swedish Academy of Sciences.

Sinha R.K.,Griffith University | Chandran V.,Griffith University | Soni B.K.,Griffith University | Patel U.,Gujarat University | Ghosh A.,An College
Environmentalist | Year: 2012

Earthworms are justifying the beliefs of Great Russian scientist Dr. Anatoly Igonin who said they are-"disinfecting, detoxifying, neutralizing, protective and productive". Studies indicate that some species of earthworms can "bio-accumulate, biodegrade or bio-transform" any toxic chemicals including "heavy metals", "organochlorine pesticide", "herbicides", and the lipophilic organic micro-pollutants like "polycyclic aromatic hydrocarbons" (PAHs). Worm vermicasts, due to the presence of "hydrophilic" groups in the "lignin contents" and "humus", also provide wonderful sites for "adsorption" of heavy metals and chemical pollutants in wastewater. Vermifiltration of wastewater using waste-eater earthworms is a newly conceived novel technology with several economic and environmental advantages. The earthworm's body and the their "vermicast" work as a "biofilter" removing BOD5 by over 90 %, COD by 60-80 %, TDSS by 90-95 %, and toxic chemicals and pathogens from wastewater. This was a pioneering work done on an extremely "toxic wastewater" from the petroleum industry. It contained mixture of "aliphatic" and "aromatic" volatile petroleum hydrocarbons (C 10-C 36) and "organochlorines" originating from the cooling liquids, waste engine and gear oil, waste transmission and brake fluid, grease, spilled petrol, and diesel oil. The aliphatic fraction contained cycloalkanes as well as a complex mixture of saturated toxic hydrocarbons. The aromatic fraction mainly consisted of PAHs, which are more toxic and persistent than the aliphatic part. The chemicals of concern were the total petroleum hydrocarbons (TPH), dichloromethane (DCM), dichloroethane (DCE), and t-butyl methyl ether (tBME). The tBME compound has raised global concern recently due to its high mobility and persistence in the environment and possible carcinogenicity. About 1,000 earthworms (species Eisenia fetida) were released in the soil of vermifilter bed. They not only tolerated and survived in the toxic petroleum environment but also bio-filtered and bio-remediated the dark-brown petroleum wastewater with a pungent smell into pale-yellow and odorless water indicating disappearance of all toxic hydrocarbons. The hydrocarbons C 10-C 14 were reduced by 99. 9 %, the C 15-C 28 by 99. 8 %, and the C 29-C 36 by 99. 7 % by earthworms. © 2012 Springer Science+Business Media, LLC.

Shwetanshumala S.,Birla Institute of Technology | Shwetanshumala S.,An College | Konar S.,Birla Institute of Technology | Biswas A.,Delaware State University
Applied Physics B: Lasers and Optics | Year: 2013

In this paper, we have shown the existence of large amounts of quintic nonlinearity in asymmetric three-coupled quantum wells, which arise due to a probe pulse and two controlling laser beams. The possibilities of generation and propagation of ultraslow bright optical solitons in these systems have been examined in situations of both Kerr and quintic nonlinearities. We have also demonstrated numerically that these solitons are stable. The modulation instability of a continuous or quasi-continuous wave probe beam has been also investigated and the role of quintic nonlinearity in suppressing this instability has been addressed. © 2013 Springer-Verlag Berlin Heidelberg.

Shwetanshumala S.,Birla Institute of Technology | Shwetanshumala S.,An College | Asif N.,Birla Institute of Technology | Konar S.,Birla Institute of Technology | Biswas A.,Delaware State University
Optik | Year: 2013

This paper presents an investigation on the propagation characteristics of optical spatial solitons in a biased centro-symmetric photorefractive medium. Unlike earlier attempts on photorefractive solitons, in the present investigation, we have given equal significance to the effects of charge drift and their diffusion. We have obtained dynamical equations for solitons employing paraxial ray approximation and examined criteria for stationary propagation. Trajectories of stationary solitons have been examined. © 2011 Elsevier GmbH.

Mukherjee A.,Indian Institute of Technology Kharagpur | Mukherjee A.,University of Texas at Austin | Scanlon B.R.,University of Texas at Austin | Fryar A.E.,University of Kentucky | And 4 more authors.
Geochimica et Cosmochimica Acta | Year: 2012

Information on groundwater chemistry in the central Ganges basin can provide insights into recharge, provenance, and fate of solutes in arsenic (As)-affected areas upstream of the more intensively studied Bengal basin. The geological and geomorphological units of the region are much more discernible than the Bengal basin aquifers. Moreover, the region is less affected by groundwater abstraction, which complicates interpretation of As distributions in the Bengal basin. The study area extends from the northern edge of the Indian craton outcrops to the foothills of the Himalayas. Geologic units in the area can be broadly classified as pre-Cenozoic metamorphics and volcanics (PC), older alluvial deposits of the Ganges and its tributaries (OA), younger or active alluvial deposits of the Ganges and its tributaries in the basin (YA), and sediments of the Himalayan foothills (piedmont, PD). Stable-isotopic analyses indicate groundwater in these units has been recharged by meteoric or surface water that has generally undergone some evaporation. The hydrochemical facies is generally a Ca-HCO 3 type. While most of the solutes in the YA groundwater are derived from carbonate dissolution, many of the PD, PC and OA groundwater samples are influenced by silicate weathering, suggesting that leaching of metamorphics and volcanics acts as a major source of solutes. Redox conditions are highly spatially variable (oxic to methanic, dominated by metal reduction), with no systematic depth variation within sampled aquifers. More than 75% of YA and PD groundwater samples have As≥0.01mg/L, but As was detected in only one OA sample and no PC samples. Arsenic is probably mobilized by reductive dissolution of Fe-Mn (oxyhydr)oxides in the alluvium, with possibility of competitive anionic mobilization. Hence, relative to the Bengal basin, in addition to lower groundwater abstraction influence, groundwater chemistry in the study area reflects a greater variety of differences in the geological and geomorphological settings of the aquifers. © 2012 Elsevier Ltd.

Shwetanshumala S.,An College
Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences | Year: 2016

Evolution of bright optical spatial solitons in biased photovoltaic photorefractive (PVPR) medium is investigated in the present work. The space-charge field developed in the medium is comprised of local and nonlocal parts. Lowest order charge drift results in the buildup of the local space-charge field, whereas higher order drift and charge diffusion are responsible for nonlocal field development. The dynamical equation for solitons in the closed circuit PVPR medium is obtained under Akhmanov's paraxial ray approximation. Conditions for stationary propagation are obtained, and the path of soliton in the medium is examined. The asymmetry in the nonlinear refractive index introduced by nonlocal contribution to the space-charge field causes a soliton to deflect from its straight line path in the medium. The roles of charge diffusion and higher order drift on soliton trajectory are examined.

Rai R.,Indian Institute of Technology Delhi | Sharma S.,An College
Advanced Materials Letters | Year: 2010

In the present paper, we synthesized the CdS hollow spheres by using PMMA sphere templates of 298-301 nm diameters and 20-51 nm of shell thickness. A CdS hollow sphere was characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), optical absorption and photoluminescence technique. CdS products are all cubic face-centered structure with the cell constant a = 5.815 Å. We also explore the morphology, structure and possible synthesis mechanism. A possible template mechanism has been proposed for the production of the hollow CdS nano-particles. The band gap of bulk CdS is about 2.45 eV, showing an absorption onset of bulk at about 513 nm. This shows a blue shift in the absorption spectra due to the quantum size effect, which is quite possible due to the small size of the CdS nano crystals as is evident in XRD pattern. The diameter of the beads is about 265-310 nm. The change in beads size due to the CdS over-layer is not so apparent in structures, due to its small thickness. The average diameter of the sphere is similar to that of the beads. Therefore, the spherical shells were obtained after the removal of PMMA core. © 2010 VBRI press.

Ahmad N.,Patna University | Sharma S.,AN College
International Journal of Nanoparticles | Year: 2012

We present a simple and eco-friendly biosynthesis of silver nanoparticles using Pomegranate peel extract as the reducing agent. The extract was challenged with AgNO 3 solution for the production of silver nanoparticles (AgNPs). The reaction process was simple for the formation of highly stable silver nanoparticles at room temperature by using the biowaste of the fruit. The morphology and crystalline phase of the NPs was determined from UV-Vis spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) spectra and Fourier-Transform IR spectroscopy (FTIR). TEM studies showed that the silver nanoparticles obtained were of sizes 5 ± 1.5 nm. An effort has also been made to understand the possible involved mechanism for the biosynthesis of AgNPs. Presumably biosynthetic products or reduced cofactors play an important role in the reduction of respective salts to nanoparticles. Copyright © 2012 Inderscience Enterprises Ltd.

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