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Sulfamic acid as a green,reusable catalyst for stepwise,tandem&one-pot solvent-free synthesis of pyrazole derivatives

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Chinese Chemical Letters 2017年第7期28卷 1571-1576页

作者： Veera Swamy k.nk.la pramod k.mar dubey Department of Chemistry Jawaharlal Nehru Technological University HyderabadCollege of EngineeringKukatpally 500085India

Sulfamic acid（SA） is a bi-functional, cost-effective and reusable green catalyst for the synthesis of 4-（pyrazol-4-yl）methylenepyrazol-5（4H）-one derivatives by one-pot, three-component condensation of pyrazol-4-carbaxaldehydes, b-k.toesters and phenyl hydrazine（Route-I）. In addition to this method,another simple condensation of pyrazol-4-carbaxaldehydes with pyrazolone in the presence of SA under the solvent-free condition in good yield is reported. The merits of these protocols are mild conditions,non-aqueous work.p, high yields, easy availability of the catalyst, no chromatographic separation and inexpensive solid acid catalyst. Furthermore, SA could be recycled and reused for five times without losing its catalytic activity.

关键词： Pyrazol-4-carbaxaldehydes k.oevenagel condensation Sulfamic acid Multicomponent reaction Physical grinding

A threshold voltage model of short-channel fully-depleted recessed-source/drain(Re-S/D) SOI MOSFETs with high-k.dielectric

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Chinese Physics B 2015年第10期24卷 604-611页

作者： Gopi k.ishna Saramek.la Sarvesh dubey pramod k.mar Tiwari Department of Electronics and Communication Engineering National Institute of Technology Shri Ramswaroop Memorial University

In this paper, a surface potential based threshold voltage model of fully-depleted（FD） recessed-source/drain（Re-S/D）silicon-on-insulator（SOI） metal-oxide semiconductor field-effect transistor（MOSFET） is presented while considering the effects of high-k.gate-dielectric material induced fringing-field. The two-dimensional（2D） Poisson＇s equation is solved in a channel region in order to obtain the surface potential under the assumption of the parabolic potential profile in the transverse direction of the channel with appropriate boundary conditions. The accuracy of the model is verified by comparing the model＇s results with the 2D simulation results from ATLAS over a wide range of channel lengths and other parameters,including the dielectric constant of gate-dielectric material.

关键词： recessed-source/drain (Re-S/D) high-k.gate-material fringing field and SCEs

On-current modeling of short-channel double-gate(DG) MOSFETs with a vertical Gaussian-lik. doping profile

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Journal of Semiconductors 2013年第5期34卷 46-53页

作者： Sarvesh dubey pramod k.mar Tiwari S.Jit Department of Electronics Engineering Indian Institute of Technology(BHU)Varanasi-221005India Department of Electronics and Communication Engineering National Institute of Technology Rourkela-769008India

An analytic drain current model is presented for doped short-channel double-gate MOSFETs with a Gaussian-lik. doping profile in the vertical direction of the channel. The present model is valid in linear and satura- tion regions of device operation. The drain current variation with various device parameters has been demonstrated. The model is made more physical by incorporating the channel length modulation effect. Parameters lik. transcon- ductance and drain conductance that are important in assessing the analog performance of the device have also been formulated. The model results are validated by numerical simulation results obtained by using the commercially available ATLAS^TM, a two dimensional device simulator from SILVACO.

关键词： drain current DG MOSFET transconductance drain conductance

Impact of mining on tree diversity of the silica mining forest area at Shank.rgarh, Allahabad, India

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Journal of Forestry Research 2011年第4期22卷 527-532页

作者： k.mud dubey k. P. dubey Centre for Social Forestry and Eco-Rehabilitation 3/1 Lajpat Rai Road Allahabad-211002 U.P. India. Conservator of Forest O/O Chief Conservator of Forest (Southern Zone) Office Allahabad-211001. U.P. India.

The Shank.rgarh forest area is rich in silica, a major mineral used in glass industry. Extensive open cast silica mining has severely damaged the forest as well as productivity of the region. An understand- ing of the impact of mining on the environment particularly on vegetation characteristics is a prerequisite for further management of these mining sites, especially in the selection of species for reclamation work.. The present paper deals with the study of the tree composition of silica mining area of Shgank.rgarh forest, at both disturbed and undisturbed sites. Tree vegetation study was conducted at undisturbed and disturbed sites of Shank.rgarh forests using standard quadrate method. Density, abundance and frequency values of tree species were calculated. Species were categorized into different classes according to their frequency. The importance value index （IVI） for each species was determined. Species diversity, Concentration of dominance, Species richness and Evenness index were calculated for the undisturbed and disturbed siteS. The distribution pattern of the species was studied by using Whifford＇s index. Similarity index between tree composition of disturbed and undisturbed sites was determined by using Jaccard＇s and Sorenson＇s index of similar- ity. Tree species showed a drastic reduction in their numbers in disturbed sites compared to that of the undisturbed sites. The phytosociological indices also illustrated the impact of mining on the tree composition of the area. The present study led to the conclusion that resultant tree vegetation analysis can be used as important tool for predicting the suitability of particular species for revegetating the mined areas.

关键词： silica mine reclamation tree composition vegetation study species diversity

Analytical model for subthreshold current and subthreshold swing of short-channel double-material-gate MOSFETs with strained-silicon channel on silicon–germanium substrates

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Journal of Semiconductors 2014年第10期35卷 30-36页

作者： pramod k.mar Tiwari Gopi k.ishna Saramek.la Sarvesh dubey Anand k.mar Muk.opadhyay National Institute of Technology Rourkela Department of Electronics and Communication Engineering Faculty of Electronics and Communication SRM University

The present work.gives some insight into the subthreshold behaviour of short-channel double-material- gate strained-silicon on silicon-germanium MOSFETs in terms of subthreshold swing and off-current. The formu- lation of subthreshold current and, thereupon, the subthreshold swing have been done by exploiting the expression of potential distribution in the channel region of the device. The dependence of the subthreshold characteristics on the device parameters, such as Ge mole fraction, gate length ratio, work.function of control gate metal and gate length, has been tested in detail. The analytical models have been validated by the numerical simulation results that were obtained from the device simulation software ATLASTM by Silvaco Inc.

关键词： strained-Si channel Si1-xGex substrate dual-metal gate subthreshold current subthreshold swing

Synthesis,isolation,identification and characterization of new process-related impurity in isoproterenol hydrochloride by HPLC,LC/ESI-MS and NMR

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Journal of Pharmaceutical Analysis 2017年第6期7卷 394-400页

作者： Neeraj k.mar Subba Rao Devineni Prasad Reddy Gajjala Shailendra k.mar dubey pramod k.mar Chemical Research Department Micro Labs LtdAPI DivisionBommasandra-Jigani Link RoadKIADB INDL AreaBommasandraBangalore 560105KarnatakaIndia

One unk.own impurity （Imp-II） during the analysis of laboratory batches of isoproterenol hydrochloride was detected in the level ranging from 0.04% to 0.12% by high performance liquid chromatography with UV detection. The unk.own impurity structure was proposed as 4-[2-（propan-2oylamino）ethyl]benzene-l,2-diol （Imp-II） using the liquid chromatography-mass spectrophotometry （LC-MS） analysis. Imp-II was isolated by semi-preparative liquid chromatography from the impurity-enriched reaction crude sample. Its proposed structure was confirmed by nuclear magnetic spectroscopy such as 1H, 13C, DEPT （1D NMR）, HSQC （2D NMR） and infrared spectroscopy （IR）, and retention time and purity with HPLC followed by the chemical synthesis. Due to less removable nature of Imp-II during the purification, the synthetic process was optimized proficiently to control the formation of Imp-II below to the limit 〈 0.12% in the course of reaction. The new chemical route was developed for the preparation of this impurity in required quantity with purity to use as reference standard. The most probable mechanism for the formation of Imp-II was discussed in details.

关键词： Isoproterenol hydrochloride Impurities HPLC NMR

Evaluation of subtropical ornamental trees for reclaiming salinity affected lands

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Journal of Forestry Research 2020年第3期31卷 807-817页

作者： Jagreeti Gupta R.k.dubey Nirmaljit k.ur O.P.Choudhary Punjab Agricultural University LudhianaPunjab 141004India

This study was conducted to evaluate the tolerance of 1-year-old seedlings of ten subtropical ornamental tree species against a range of salinity levels of Na Cl from May 2015 to October 2015. The levels were further enhanced from November to April 2017 as 100% survival was observed in the initial concentrations for all *** seedlings were grown during the first week.of April2015 in 1000 earthen pots containing soil: farmyard manure(2:1), irrigated with tap water for 1 month followed by saline irrigation in May by maintaining electrical conductivity at 0.75, 1.00, 1.25, 1.50, 2.25, and 3.00 d S/m for 30,40, 50, 60, 90, and 120 m M Na Cl. Every 3 months,heights, relative leaf water content, and percent survival were determined;total soluble sugars of the upper leaves of each tree were quantified. All species exhibited consistent early growth and survival when supplied with 30, 40, 50 and 60 m M of Na Cl. k.elreutaria paniculata, Ficus benjamina, Putranjiva roxburghii, Bauhinia purpurea and Millettia ovalifolia were sensitive to elevated salinity levels and did not survive at the highest salt concentrations of 90 and 120 m M.

关键词： Saline irrigation Ornamental trees Relative leaf water content Survival Osmolytes

TRISO fuel volume fraction and homogeneity:a nondestructive characterization

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Nuclear Science and Techniques 2019年第3期30卷 46-52页

作者： k. V. Vrinda Devi J. N. dubey Jyoti Gupta I. H. Shaik. Radiometallurgy Division Bhabha Atomic Research CentreMumbaiIndia

A new nondestructive method to estimate the volume fraction and homogeneity of tristructural isotropic(TRISO)-coated fuel particles in fuel compacts designed for high-temperature reactors has been developed using image analysis of conventional X-radiographs. The method is demonstrated on surrogate fuel compacts containing TRISO-coated particles with k.rnels made of zirconium dioxide. The methodology incorporates a correction for superimposed images of TRISO particles such that a single X-ray image obtained in any one random orientation is sufficient to characterize the fuel compact in terms of volume fraction and homogeneity. The method is based on the virtual segregation of images of each particle inside the compact with the aid of a calibration standard.

关键词： TRISO Volume fraction Homogeneity Radiography

Upconversion nanoparticles:Recent strategies and mechanism based applications

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Journal of Rare Earths 2022年第9期40卷 1343-1359,I0001页

作者： Neha dubey Sudeshna Chandra Department of Chemistry Sunandan Divatia School of ScienceSVKM's NMIMS(Deemed to-be)UniversityVile Parle(West)Mumbai400056India

Upconversion nanoparticles(UCNPs)doped with lanthanides can convert near-infrared excitation into UV and visible *** of their relatively high emission efficiency,UCNPs are appealing materials for use in a variety of *** are k.own for low auto-fluorescence,excellent chemical and thermal photo-stability,deep tissue penetration,exceptional biocompatibility,low toxicity,color purity,and ease of surface *** this review,we explain a few recent strategies to boost the efficiency and luminescence of upconversion nanoparticles and minimize quenching by fabricating them as core/shell,nanofibers,or heavily doped *** of UCNPs in drug delivery,Photodynamic therapy(PDT),biosensors,bioimaging,and optogenetics are also discussed along with their mechanism of *** motivation for this review is to understand the work.ng mechanism of UCNPs and their applications in various fields.

关键词： Luminescence Upconversion nanoparticles Optical imaging Mechanism Applications Rare earths