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Photo-induced optical changes in GexAs40Se60-x thin films

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Progress in Natural Science:Materials International 2010年第1期20卷 54-60页

作者： Rashmi CHAUHAN Amit Kumar srivastava Arvind TRIPATHI krishna kant srivastava Department of Physic DAV College Kanpur 208001India Material Science Programme ⅡT Kanpur 208016 India Epsilonium Systems Commercial Complex ChunniganjKanpur 208001India Department of Physics DBS College Kanpur 208006India

Ge-As-Se chalcogenide thin films show a wide range of photosensitivity,which is utilized for the fabrication of micro-optical elements for integrated *** photosensitivity of GexAs40Se60-x（x=0,15）chalcogenide thin films for UV light was *** that purpose,the bulk samples of GexAs40Se60-x（x=0,15）chalcogenide glasses were prepared using conventional melt quenching technique,and thin films were prepared using thermal evaporation *** thin films were exposed to UV light for two *** natures of bulk samples and thin films were verified by XRD and chemical compositions were verified by EDX *** thicknesses of the thin films were measured using a thickness *** optical analysis of these thin films was done using transmission spectra in wavelength range of 300-900 *** bandgap was determined by first peak of transmission derivative as well as extrapolation of Tauc's plot.R2analysis was done using R software to ensure that the material is indirect bandgap *** is observed that two hours UV exposure causes photo-darkening along with photo-expansion in As40Se60thin films,while photo-bleaching and photo-densification for Ge15As40Se45thin ***,the amounts of photo-induced optical changes for Ge15As40Se45thin films are smaller than those for As40Se60thin *** changes in optical absorption,bandgap and thickness are understood based on the bonding rearrangement caused by UV exposure.

关键词： chalcogenide glasses thin films optical properties photo-induced effect optical band gap UV exposure R software

High-energy ion treatments of amorphous As40Se60 thin films for optical applications

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Progress in Natural Science:Materials International 2014年第3期24卷 239-246页

作者： Rashmi Chauhan Arvind Tripathi krishna kant srivastava Department of Physic DAV College CSJM University Research Foundation for Education and Technology Department of Physics DBS College CSJM University

The treatment of 100 MeV Ag swift-heavy ion(SHI) irradiation with five different fluences(3 1010, 1 1011, 3 1011, 1 1012, and3 1012ions/cm2) was used to design optical and structural properties of amorphous(a-) As40Se60 chalcogenide thin films. Swanepoel method was applied on transmission measurements to determine the changes in optical bandgap, Tauc parameter and linear optical parameters, i.e., linear optical absorption, extinction coefficient and linear refractive index. Dispersion of the material was determined by Wemple–DiDomenico *** in nonlinear optical parameters of third-order optical susceptibility and nonlinear refractive index were determined using semi-empirical relations. Changes in surface morphology of the films were investigated using SEM observation, which indicated that fluence 3 1012ions/cm2was upper threshold limit for these films for ion treatment. It is observed that optical bandgap reduces from 1.76 eV to 1.64 eV, and nonlinear refractive index increases from 1.31 10 10[esu] to 1.74 10 10[esu]. Linear refractive index initially increases from 2.80 to 3.52(for fluence3 1010ions/cm2) and then keeps decreasing. The observed changes in optical properties upon irradiation were explained in terms of structural rearrangements by Raman measurement. The study was compiled with the previous literature to propose SHI as an effective optical engineering technique to achieve desired changes according to the need of optical/photonic applications.

关键词： Amorphous chalcogenide thin films Ion irradiation Linear and nonlinear optical properties Swanepoel method Semi-empirical relations Raman measurements

Arbuscular Mycorrhizal (AM) Diversity in Prosopis cineraria (L.) Druce Under Arid Agroecosystems

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Agricultural Sciences in China 2008年第6期7卷 754-761页

作者： Neelam Verma Jagadish Chandra Tarafdar krishna kant srivastava Jitendra Panwar Arid Forest Research Institute Jodhpur 342 005 Rajasthan India Central Arid Zone Research Institute Biological Sciences Group Birla Institute of Technology & Science

Arbuscular mycorrhizal （AM） fungi associated with Prosopis cineraria （Khejri） were assessed for their qualitative and quantitative distribution from eight districts of Rajasthan. A total of three species of Acaulospora, one species of Entrophospora, two species of Gigaspora, twenty-one species of Glomus, seven species of Sclerocystis and three species of Scutellospora were recorded. A high diversity of AM fungi was observed and it varied at different study sites. Among these six genera, Glomus occurred most frequently. Glomus fasciculatum, Glomus aggregatum, and Glomus mosseae were found to be the most predominant AM fungi in infecting Prosopis cineraria. Acaulospora, G. fasciculatum, Sclerocystis was found in all the fields studied, while Scutellospora species were found only in few sites. A maximum of thirty-six AM fungal species were isolated and identified from Jodhpur, whereas only thirteen species were found from Jaisalmer. Spores of Glomusfasciculatum were found to be most abundant under Prosopis cineraria.

关键词： arbuscular mycorrhizae arid agroecosystems diversity Prosopis cineraria

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Decline of Japanese encephalitis in Eastern Uttar Pradesh,India,2009-2019

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Asian Pacific Journal of Tropical Medicine 2022年第5期15卷 230-231页

作者： Neha srivastava Hirawati Deval Nikhat Khan Rajni kant Aparup Das ICMR-Regional Medical Research Centre BRD Medical College CampusGorakhpurUttar Pradesh273013India ICMR-National Institute of Research in Tribal Health Nagpur RoadGarhaJabalpurMadhya Pradesh482003India

Japanese encephalitis(JE),one of the major viral encephalitides,is caused by Flavivirus circulating in rural areas of Asia and Western Pacific regions[1]and is a neglected tropical viral disease due to its endemicity[2].The culicine mosquitoes,mainly of Culex tritaeniorhynchus and Culex vishnui group,are the vectors of JE virus(JEV)[1].Being a neurologic infection,JE manifests with a set of serious symptoms leading to death in many cases and/or change in behaviour of the patients leading to permanent disability[3].

关键词： encephalitis Eastern neglected

Preventive strategies to innovate Japanese encephalitis control in eastern Uttar Pradesh: Accelerating towards zero incidence

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Asian Pacific Journal of Tropical Medicine 2023年第4期16卷 145-147页

作者： Neha srivastava Rohit Beniwal Brij Ranjan Misra Umaer Alam Hirawati Deval Rajni kant ICMR-Regional Medical Research Centre GorakhpurUttar PradeshIndia

Japanese Encephalitis(JE)is a zoonotic mosquito-borne viral disease that primarily affects young children under the age of 15[1].Annually,there are more than 50000 clinical cases and JE causes over 10000 fatalities globally[1].In Japan,South Korea,China and Thailand,where it is now under control or almost entirely eradicated,the disease was initially noted to have a high incidence[1].Later,it expanded to Nepal and India,becoming a serious public health issue in rural regions[1].JE is a flavivirus-based neglected tropical disease that is spread by culicine mosquitoes of the Culex(Cx.)tritaeniorhynchus and *** species[2].

关键词： entirely neglected expanded

High Phenotypic Variation in Morus alba L. along an Altitudinal Gradient in the Indian Trans-Himalaya

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Journal of Mountain Science 2015年第2期12卷 446-455页

作者： Prabodh K. BAJPAI Ashish R. WARGHAT Ashish YADAV Anil kant Ravi B. srivastava Tsering STOBDAN Defence Institute of High Altitude Research DRDO Leh Jammu and Kashmir 194101 India Jaypee University of Information Technology Waknaghat Solan Himachal Pradesh 173215 India

Ten quantitative morphological characters were studied in 56 Morus alba L. trees representing three natural populations from the trans-Himalayan Ladakh region. The altitude of collection sites ranged from 2815 to 3177 m above the sea level(asl). Coefficient of variation(CV) showed high phenotypic variation in M. alba. Linear regression analysis revealed that leaf and fruit size decreases with an increase in altitude. High CV was observed for leaf length, leaf width, petiole length, leaf area, internodal distance, number of nodes, bud length, fruit length, fruit width and fruit weight. Similarly, a high phenotypic plasticity index was observed for bud length, leaf length, leaf width, petiole length, leaf area, inter-nodal distance, number of nodes, fruit length, fruit width and fruit weight. For every 100 m increase in altitude, leaf length, leaf width and leaf area decreased by 1 cm, 0.8 cm and 16.6 cm2, respectively. Analysis of covariance showed a predominant altitudinal effect on the morphological characters in comparison to the population effect. A small change in the altitude caused significant change in the plant morphological characteristics. The present investigation represents to our knowledge the first study addressing phenotypic variation in mulberryalong an altitudinal gradient.

关键词： Adaptation Ladakh Leaf Morphometry Mulberry Morus alba Stress

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Molecular Profiling of Drug Resistant Isolates of <i>Mycobacterium tuberculosis</i>in North India

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Advances in Microbiology 2012年第3期2卷 317-326页

作者： Dinesh K. Tripath Kanchan srivastava Surya kant Kishore K. srivastava Department of Microbiology Central Drug Research Institute Lucknow India Department of Pulmonary Medicine CSMMU Lucknow India

Multidrug-resistant tuberculosis (MDR-TB) is a major public health problem because treatment is complicated, cure rates are well below those for drug susceptible tuberculosis (TB), and patients may remain infectious for months or years despite receiving the best available therapy. To gain a better understanding of MDR-TB, we characterized isolates recovered from 69 patients with MDR-TB, by use of IS6110 restriction fragment-length polymorphism (RFLP) analysis;spacer oligonucleotide genotyping (i.e. spoligotyping). Clinical isolates from patients with tuberculosis have been considered to contain clonally expanded Mycobacterium tuberculosis (MTB) strain. Over the years, the identification method based on IS6110 insertion sequences has been established as the standard for typing strains of MTB. IS6110 RFLP fingerprinting is very convincing when it is applied to classify MTB isolates harboring a large number of IS6110 in their chromosomes. Therefore, in the present study we have characterized the isolates from the patients suffering from MDR TB, on the basis of conserved Variable Number Tandem Repeats (VNTR), Direct Repeats (DR) and Insertion Sequences (IS) IS6110 elements. The polymorphic data showed significant level of dissimilarities among all the MDR isolates of MTB. Comparative studies with the DR and VNTR data substantiate that polymorphism occur among MDR-TB cases as shown by the number of repeats present in different clinical isolates.

关键词： Mycobacterium Drug Resistance IS6110 Polymorphism