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Characterization and Biodegradation Studies for Interpenetrating Polymeric Network (IPN) of Chitosan-Amino Acid Beads

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Journal of Biomaterials and Nanobiotechnology 2011年第1期2卷 71-84页

作者： Manjusha Rani Anuja Agarwal yuvraj singh negi 不详

The paper describes the synthesis of pH sensitive interpenetrating polymeric network (IPN) beads composed of chi-tosan, glycine, glutamic acid, cross linked with glutaraldehyde and their use for controlled drug release. The drug was loaded into beads by varying their composition such as, amount of crosslinker glutaraldehyde, ratio of chitosan, glycine and glutamic acid. The beads were characterized by fourier transform infrared (FTIR) spectroscopy to confirm the cross linking reaction and drug interaction with crosslinked polymer in beads, Scanning Electron Microscopy (SEM) to understand the surface morphology and Differential scanning calorimetry (DSC) to find out the thermal stability of beads. X-Ray Diffraction (XRD) investigation was carried out to determine the crystalline nature of drug after loading into chitosan-glycine-glutamic acid IPN beads. Results indicated amorphous dispersion of chlorpheniramine maleate (CPM) in the polymeric matrix. The swelling behavior of the beads at different time intervals was monitored in solutions of pH 2.0 and pH 7.4. The release experiments were performed in solutions of pH 2.0 and pH 7.4 at 37oC using chlorpheniramine maleate (CPM) as a model drug. The swelling behavior and release of drug were observed to be dependent on pH, degree of cross linking and their composition. The results indicate that the cross linked IPN beads of chitosan-glycine-glutamic acid might be useful as a vehicle for controlled release of drug. The kinetics of drug release from beads was best fitted by Higuchi’s model in which release rate is largely governed by rate of diffusion through the matrix.

关键词： Cross-Linked Beads Chitosan Chlorpheniramine Maleate Glycine Glutamic Acid Controlled Drug Release

Assessment of glacier stored water in Karakoram Himalaya using satellite remote sensing and field investigation

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Journal of Mountain Science 2019年第4期16卷 836-849页

作者： Kamal Kant singh Harendra singh negi Dhiraj Kumar singh Snow and Avalanche Study Establishment

Karakoram Himalaya(KH) has continental climatic conditions and possesses largest concentration of glaciers outside the polar regions. The melt water from these glaciers is a major contributor to the Indus river. In this study, various methods have been used to estimate the ice volume in the Karakoram Range of glaciers such as Coregistration of Optically Sensed Images and Correlation(COSI-Corr) method and Area-Volume relations. Landsat 8 satellite data has been used to generate the ice displacement, velocity and thickness map. Our study for 558 Karakoram glaciers revealed that the average ice thickness in Karakoram is 90 m. Ground Penetrating Radar(GPR) survey has been conducted in one of the KH glacier i.e. Saser La glacier and the collected GPR data is used for the validation of satellite derived thickness map. GPR measured glacier thickness values are found comparable with satellite estimated values with RMSE of 4.3 m. The total ice volume of the Karakoram glaciers is estimated to be 1607±19 km3(1473±17 Gt), which is equivalent to 1473±17 km3 of water equivalent. Present study also covers the analysis of glacier surface displacement, velocity and ice thickness values with reference to glacier mean slope.

关键词： Glacier COSI-Corr Karakoram Range Ground Penetrating Radar GPR Volume-Area

Graphene derivatives as efficient hole transport materials for lead-free double perovskite（Cs2SnI6） solar cells: a numerical study

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Optoelectronics Letters 2025年第3期 155-159页

作者： Sarita YADAV Saral K.GUPTA Chandra Mohan singh negi Department of Physical Science Banasthali Vidyapith

The double perovskite Cs2SnI6has notable optical and electrical characteristics, rendering it a highly prospective candidate for deployment as the absorber layer in perovskite solar cells （PSCs）. We simulated the performance of PSCs using lead-free Cs2SnI6double perovskite absorber layer and graphene derivatives, namely graphene oxide （GO） and reduced graphene oxide （rGO）, as hole transport layers （HTLs）. Our findings show that r GO offers an excellent hole extraction property with minimal interfacial recombination compared to GO.

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Effects of irregularity and initial stresses on the dynamic response of viscoelastic half-space due to a moving load

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Acta Mechanica Solida Sinica 2017年第3期30卷 306-317页

作者： A.K. singh A. Das A. Lakshman A. negi A. Chattopadhyay Department of Applied Mathematics Indian Institute of Technology (Indian School of Mines) Dhanbad 826004 Jharkhand India

The present article deals with the stresses developed in an initially stressed irregular viscoelastic half-space clue to a load moving with a constant velocity at a rough free surface. Expressions for normal and shear stresses are obtained in closed form. The substantial effects of influence parameters, viz., depth （from the free surface）, irregularity factor, maximum depth of irregularity, viscoelastic parameter, horizontal and vertical initial stresses, and frictional coefficient, on normal and shear stresses are investigated. Moreover, comparative study is carried out for three different cases of irregularity, viz., rectangular irregularity, parabolic irregulariW and no irregularity, which is manifested through graphs.

关键词： Viscoelastic Irregularity Moving load Frictional coefficient Stresses

A new flavone C-glucoside from Glycosmis arborea(Rutaceae)

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Chinese Chemical Letters 2010年第12期21卷 1443-1445页

作者： Rajni Kant Sharma Sushma Semwal Devendra singh negi Department of Chemistry HNB Garhwal Central University SrinagarUttarakhandIndia Department of Chemistry University of Cape TownCape TownRondebosch 7701South Africa

A new C-glycosyl flavone 7,4＇-dihydroxy-5-methoxyflavone-6-C-β-D-glucopyranoside 1 has been isolated and characterized form ethanolic extract of leaves part of Glycosmis *** structure of compound was verified by mea... 详细信息

关键词： Glycosmis arborea Rutaceae Flavone C-glucoside

Ethnobotanical and Indigenous Knowledge of Important Plants in East Hararghe, Eastern Ethiopia

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Journal of Mountain Science 2015年第6期12卷 1521-1533页

作者： Laxman singh KANDARI Tripti negi Ashok Kumar THAKUR Eshetu YILMA Department of Forestry Himgiri Zee University Don Paramedical college and Hospital School of Plant Science College of Agriculture and Environmental Sciences Haramaya University

An ethnobotanical study was conducted in East Hararghe, Ethiopia to identify and investigate the use of various plants by the traditional healers and communities engaged in domestic, pesticide and medicinal use. A total of 78 species were observed to be used by the local inhabitants in the region for the treatments of various ailments. Out of these, herbs constitute 49% followed by trees(36%) and shrubs only 15%. However, most frequently used plant parts were leaf and aerial parts(20) followed by seed(13), fruit(12), other parts(10), rhizome(7) and bark(1). Most of the plants were found to be used for medicinal, aromatic and food flavouring(spices, condiments) purposes. Out of 78 species recorded in the present study, 11 were reported to cure stomachache, seven for cold, cough and respiratory problem, six for diarrhoea and five species were found capable of curing fever. Fabaceae was the largest family contributing to medicinal plant use with seven species followed by Solanaceae, Myrtaceae,(5 spp.), and Zingiberaceae, Asteraceae, Liliaceae(4 spp. each). Some of the important plants utilized for taking care of variety of ailments are Azadirachta indica, Brassica nigra, Balanites aegyptiaca, Maytenus ovatus, Rosmarinus officinalis and Trigonella foenum graecum. Most of these medicinal and aromatic plants(MAPs) play a significant role in the household economy and were observed to be very popular among the people. Unpopular plants were left out of the study. This study provides useful and basic information on usage of different plants for conducting further studies aimed at conservation and documentation of traditional medicine system and economic welfare of rural peoples of the East Hararghe, Ethiopia. It also revealed that indigenous practices contributed to sustainable management of plants.

关键词： Ethnobotany Medicinal plants Primary health care Traditional knowledge East Hararghe

Impact of source and drain contact thickness on the performance of organic thin film transistors

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Journal of Semiconductors 2014年第12期35卷 21-27页

作者： Poornima Mittal Y.S.negi R.K.singh Department of Electronics & Communication Engineering Graphic Era UniversityDehradun–248002 India Department of Electronics & Communication Engineering Uttarakhand Technical UniversityDehradun–248002 India Department of Polymer and Process Engineering Indian Institute of Technology Roorkee–246776 India

This paper analyzes the impact of source（ts） and drain（td） contact thicknesses on top contact（TC） and bottom contact（BC） organic thin film transistors（OTFTs） with a gate in the bottom, using a benchmarked industry standard Atlas 2-D numerical device simulator. The parameters including drive current（Ids）, mobility（μ）, threshold voltage（Vt）and current on-off ratio（ION/IOFF） are analyzed from the device physics point of view on different electrode thicknesses, ranging from infinitesimal to 50 nm, for both top and bottom contact structures. Observations demonstrate that the performance of the BC structure is more affected by scaling of ts=din comparison to its counterpart. In the linear region, the mobility is almost constant at all the values of ts=dfor both structures. However,an increment of 18% and 83% in saturation region mobility is found for TC andBC structures, respectively with scaling down ts=dfrom 50–0 nm. Besides this, the current on-off ratio increases more sharply in the BC *** analysis simplifies a number of issues related to the design and fabrication of organic material based devices and circuits.

关键词： contact thickness organic semiconductor organic thin film transistor bottom contact top contact structure

Prevalence of transfusion transmissible infections among various donor groups:A comparative analysis

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World Journal of Virology 2025年第1期14卷 108-117页

作者： Sanjay K Thakur Anil K Sinha Santosh K Sharma Aarzoo Jahan Dinesh K negi Ruchika Gupta Sompal singh Regional Blood Transfusion Centre Hindu Rao Hospital and NDMC Medical CollegeNorth Delhi 110007DelhiIndia Department of Zoology Veer Kunwar Singh UniversityAra 802301BiharIndia Regional Blood Transfusion Centre and Pathology Hindu Rao Hospital and NDMC Medical CollegeNorth Delhi 110007DelhiIndia Department of Cytopathology ICMR-National Institute of Cancer Prevention and ResearchNoida 201301Uttar PradeshIndia

BACKGROUND Transfusion transmissible infections(TTIs)are illnesses spread through contaminated blood or blood *** India,screening for TTIs such as hepatitis B virus(HBV),hepatitis C virus(HCV),human immunodeficiency virus(HIV)-I/II,malaria,and syphilis is mandatory before blood ***,HCV,HBV,and HIV are the leading viruses causing mortality,affecting millions of people globally,including those with co-infections of HIV/HCV and HIV/*** highlight the impact of TTIs on life expectancy and health risks,such as liver cirrhosis,cancer,and other diseases in individuals with chronic ***,millions of blood donations take place annually,emphasizing the importance of maintaining blood *** To study the prevalence of TTIs,viz.,HBV,HCV,HIV I/II,syphilis,and malaria parasite(MP),among different blood donor *** The study assessed the prevalence of TTIs among different blood donor groups in Delhi,*** included total donors,in-house donors,total camp donors,institutional camp donors,and community camp *** for HIV,HBV,and HCV were done using enzyme-linked immunosorbent assay,while syphilis was tested with rapid plasma reagins and MP rapid card *** prevalence of HBV,HCV,HIV,and syphilis,expressed as *** in infection rates between the groups were analyzed usingχ²tests and P-values(less than 0.05).RESULTS The study evaluated TTIs among 42158 blood donors in *** overall cumulative frequency of TTIs in total blood donors was 2.071%,and the frequencies of HBV,HCV,HIV-I/II,venereal disease research laboratory,and MP were 1.048%,0.425%,0.221%,0.377%,and 0.0024%,***-house donors,representing 37656 donors,had the highest transfusion transmissible infection(TTI)prevalence at 2.167%.Among total camp donors(4502 donors),TTIs were identified in 1.266%of donors,while community camp donors(2439 donors)exhibited a prevalence of 1.558%.Institutional camp donors(2063 donors)had the l

关键词： Blood donors Transfusion transmissible infections Hepatitis B virus Human immunodeficiency virus Hepatitis C virus Malaria parasite Syphilis

Experimental and simulation studies for optimization of waterealternating-gas(CO2)flooding for enhanced oil recovery

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Petroleum Research 2020年第3期5卷 227-234页

作者： Swapnil Pancholi Gudendra singh negi Jatin R.Agarwal Achinta Bera Maunish Shah Drilling Cementing and Stimulation Research CenterSchool of Petroleum TechnologyPandit Deendayal Petroleum UniversityGandhinagarGujarat382007India

The paper deals with the screening of injection of water-alternating-gas(WAG)to tap the residual oil saturation left in the reservoir by over and above the water *** detailed mineralogical composition has been studied by X-ray diffraction(XRD)method along with the petrophysical parameters to see their impacts of flow on Himmatnagar(India)***,aromatics,resins,and asphaltenes present in the crude oil were determined by ASTM *** miscibility pressure of CO2 with the crude oil was determined and it has been found at 1254 psi based on thermodynamic *** WAG ratios of 1:1,1.5:1 and 2:1 have been applied for EOR during *** on water injection followed by CO2 has been performed for investigation of the WAG process efficiency.A total 2 cycles of WAG injection was done with water flow rate of 1 ml/min and gas injection pressure around 1250 psi to achieve the better contact *** experimental data has been generated,compiled and interpreted during different cycles of WAG *** was observed that WAG ratio 2:1 exhibits highest additional oil recovery around 34%of original oil in *** WAG ratio yields more additional oil recovery.

关键词： Water-alternating-gas injection Minimum miscibility pressure Enhanced oil recovery WAG ratio WAG cycle