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Cloning ＆ sequence identification of Hsp27 gene and expression analysis of the protein on thermal stress in Lucilia cuprina

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Insect Science 2016年第4期23卷 555-568页

作者： Manish k. Singh Pramod k. Tiwari Center for Genomics Molecular & Human Genetics Jiwaji University Gwafior 474011 Cytogenetics Laboratory Department of Zoology Banaras Hindu University Varanasi 221005 India

Hsp27, a highly conserved small molecular weight heat shock.protein, is widely k.own to be developmentally regulated and heat inducible. Its role in thermotolerance is also implicated. This study is a sequel of our earlier studies to understand the molecular organization of heat shock.genes/proteins and their role in development and thermal adaptation in a sheep pest, Lucilia cuprina （blowfly）, which exhibits unusually high adaptability to a variety of environmental stresses, including heat and chemicals. In this report our aim was to understand the evolutionary relationship of Lucilia hsp27 gene/protein with those of other species and its role in thermal adaptation. We sequence characterized the Lchsp27 gene （coding region） and analyzed its expression in various larval and adult tissues under normal as well as heat shock.conditions. The nucleotide sequence analysis of 678 bps long-coding region of Lchsp27 exhibited closest evolutionary proximity with Drosophila （90.09%）, which belongs to the same order, Diptera. Heat shock.caused significant en- hancement in the expression ofLchsp27 gene in all the larval and adult tissues examined, however, in a tissue specific manner. Significantly, in Malpighian tubules, while the heatinduced level ofhsp27 transcript （mRNA） appeared increased as compared to control, the protein level remained unaltered and nuclear localized. We infer that Lchsp27 may have significant role in the maintenance of cellular homeostasis, particularly, during summer months, when the fly remains exposed to high heat in its natural habitat.

关键词： heat shock.protein Hsp27 Lucilia cuprina thermal stress

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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

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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

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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

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The correlation between friction coefficient and areal topography parameters for AISI 304 steel sliding against AISI 52100 steel

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Friction 2021年第1期9卷 41-60页

作者： Deepak.k.PRAJAPATI Mayank.tiwari Department of Mechanical Engineering Indian Institute of TechnologyPatna 801103India

Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in which asperity interactions play a significant role in controlling of the friction coefficient(f). The purpose of this work.is to study the tribological behavior of AISI 304 steel in contact with AISI 52100 steel during wear. Both materials are used in rolling element bearings commanly. Experiments are carried out using a pin-on-disc tribometer under dry friction condition. The areal(three dimensional, 3D) topography parameters are measured using a 3D white light interferometer(WLI) with a 10× objective. After wear tests, wear mechanisms are analyzed utilizing scanning electron microscope(SEM). Factorial design with custom response surface design(C-RSD) is used to study the mutual effect of load and speed on response variables such as f and topography parameters. It is observed that the root mean square roughness(S_(q)) decreases with an increase in sliding time. Within the range of sliding time, S_(q) decreases with an increase in the normal load. Within the range of sliding speed and normal load, it is found that S_(q), mean summit curvature(S_(sc)), and root mean square slope(S_(dq)) are positively correlated with f. Whereas, negative correlation is found between f and correlation length(Sal), mean summit radius(R), and core roughness depth(S_(k.).

关键词： friction coefficient(f) areal topography parameters factorial design non-contact optical profiler scanning electron microscope(SEM)

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Analog and radio-frequency performance analysis of silicon-nanotube MOSFETs

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Journal of Semiconductors 2016年第6期37卷 60-63页

作者： pramod k.mar tiwari muk.sh k.mar ramavathu sak.u naik.gopi k.ishna saramek.la Department of Electronics and Communication Engineering National Institute of TechnologyRourkela-769008OdishaIndia

This work.presents a comparative study of the influence of various parameters on the analog and RF properties of silicon-nanotube MOSFETs and nanowire-based gate-all-around（GAA） MOSFETs.The important analog and RF performance parameters of SiNT FETs and GAA MOSFETs,namely drain current（/d）,transconductance to drain current ratio（g_m/I_d）,I_（on）/I_（off）,the cut-off frequency（f_T） and the maximum frequency of oscillation（/max） are evaluated with the help of Y- and H-parameters which are obtained from a 3-D device simulator,ATLAS^（TM）.It is found that the silicon-nanotube MOSFETs have far more superior analog and RF characteristics（g_m/I_d,f_T and /max） compared to the nanowire-based gate-all-around GAA MOSFETs.The silicon-nanotube MOSFET shows an improvement of ~2.5 and 3 times in the case of f_T and /max values respectively compared with the nanowire-based gate-all-around（GAA） MOSFET.

关键词： analog and RF SiNT MOSFETs GAA MOSFETs unity gain frequency unity power frequency

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Regeneration of tree species in the sub-tropical forest of Alak.anda Valley, Garhwal Himalaya, India

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Forestry Studies in China 2013年第2期15卷 89-97页

作者： Radha BALLABHA J. k. tiwari P. tiwari Department of Botany and Microbiology HNB Garhwal UniversitySrinagar Garhwal 246174 Uttarakhand India

We studied the regeneration of tree species in the sub-tropical forest of Alak.anda Valley in Garhwal Himalaya, India. The overall regeneration status was fairly good in the study area. Seedling density ranged between 520 and 1,240 seedlings per ha while the density of saplings varied between 400 and 800 saplings per ha. Out of eight sites studied, five sites, viz., A1, A2, B1, B2 and C2 contained the highest number of seedlings （280-480 per ha） and saplings ,（200-440 per ha） for Pinus roxburghfi and remaining three sites viz., C1, D1 and D2 represented the highest number of seedlings （240-400 per ha） and saplings （200-240 per ha） for Anogeissus latifolius. The DBH class distribution of the tree species revealed that the highest number of individuals was concentrated in the lower diameter classes while smallest numbers were found in the higher diameter classes. Species such as Acacia catechu, Anogeissus latifolius, Dalbergia sissoo, Engelhardtia spicata, Lannea coromandelica, Mallotus philippensis and Pinus roxburghii have the larg- est number of saplings and seedlings in the lower DBH classes, suggesting that they have good regeneration potential. Other spec es such as Aegle marmelos, Bauhinia variegata, Bombax ceiba, Cassia fistula, Erythrina variegata, Haldinia ：cordifolia, Mangifera indica, Ougeinia oojeinensis, Phyllanthus emblica, Syzygium cumini, Terminalia alata and Toona hexandra have either no or very small number of saplings in the lower DBH classes which indicates that the status of these species implies poor regeneration.

关键词： Garhwal Himalaya disturbances regeneration tree species

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Mechanical properties and thermal conductivity of pristine and functionalized carbon nanotube reinforced metallic glass composites:A molecular dynamics approach

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Defence Technology（防务技术） 2021年第1期17卷 234-244页

作者： Sumit Sharma S.k.tiwari Sagar Shak.a Department of Mechanical Engineering Dr.B.R.Ambedkar National Institute of TechnologyJalandharIndia

This work.uses the molecular dynamics approach to study the effects of functionalization of carbon nanotubes(CNTs)on the mechanical properties of Cu64Zr36 metallic glass(MG).Three types of functional groups,carboxylic,vinyl and ester were used.The effect of CNT volume fraction(Vf)and the number of functional groups attached to CNT,on the mechanical properties and thermal conductivity of CNT-MG composites was analysed using Biovia Materials Studio.At lower values of Vf(from 0 to 5%),the percentage increase in Young’s modulus was approximately 66%.As the value of Vf was increased further(from 5 to 12%),the rate of increase in Young’s modulus was reduced to 16%.The thermal conductivity was found to increase from 1.52 W/mk.at Vf?0%to 5.88 W/mk.at Vf?12%,thus giving an increase of approximately 286%.Functionalization of SWCNT reduced the thermal conductivity of the SWCNT-MG composites.

关键词： Molecular dynamics Carbon nanotube Metallic glass Mechanical properties Thermal conductivity

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Harmful algal blooms in fresh and marine water systems： The role of toxin producing phytoplank.on

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International Journal of Biomathematics 2016年第3期9卷 191-210页

作者： Nilesh k.mar Thak.r S. k. tiwari Ranjit k.mar Upadhyay Department of MathematicsNational Institute of Technology Raipur 492010 Department of Applied MathematicsIndian School of Mines Dhanbad 826004

In this paper, we have investigated a model with three interacting species: non-toxic phytoplank.on, toxic phytoplank.on and zooplank.on with Holling type II and III functional responses over the space and time. The role of toxin producing phytoplank.on (TPP) has been studied. We have presented the theoretical analysis of pattern formation in spatially distributed population with local diffusion. The paper highlights the heterogeneity of HABs over space and time. The choice of parameter values and the functional response is important to study the effect of TPP, also it would depend more on the nonlinearity of the system. With the help of numerical simulations, we have observed the spatial and spatiotemporal patterns for plank.on system. This study demonstrates that TPP plays an important role in controlling the dynamics. We have observed that prey's anti-predator efforts promote predator switching. It has been found that high predation of TPP helps for the coexistence of toxic, non-toxic phytoplank.on and zooplank.on population. [ABSTRACT FROM AUTHOR]

关键词：浮游植物有害藻类海水系统 Holling 产毒繁殖淡水功能反应

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Tree species composition and diversity in montane forests of Garhwal Himalaya in relation to environmental and soil properties

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Journal of Mountain Science 2020年第12期17卷 3097-3111页

作者： Dinesh Singh RAWAT P.tiwari Sudipta k.mar DAS J.k.tiwari Department of Botany&Microbiology HNB Garhwal UniversitySrinagar(Garhwal)-246174UttarakhandIndia Central National Herbarium Botanical Survey of IndiaHowrah-711103West BengalIndia

The montane forests of Garhwal Himalaya were investigated for tree species composition and diversity in relation to environmental and edaphic variables.A stratified random sampling approach was adopted to collect the field data from each forest.A total of 39 tree species belonging to 31 genera and 23 families were recorded from the sampling area(6 forest stands ×10 plots in each).Lauraceae with 5 species was the largest family while Quercus(4 species) emerged as the largest genus.Species-area curve(asymptote) predicted more species than the observed number of species.Cluster analysis has shown that the two Abies pindrow dominant forest stands had the highest similarity in tree species composition.The tree stem density ranged from 540-1170 ha-1,basal area 23.01-55.94 m^2 ha-1,ShannonWiener diversity index 1.69-2.49,evenness index0.42-0.74,beta diversity 0.40-0.82 and similarity index 0.17-0.54 in the six studied forests.Two-way indicator species analysis(TWINSPAN) identified four distinct tree communities in the study area with Daphniphyllum himalayense,Abies pindrow,Quercus oblongata,and Pinus roxburghii as indicator species of corresponding communities.Canonical correspondence analysis(CCA) ascertained the TWINSPAN results and revealed the relation of tree species with environmental and edaphic variables.The phytosociological attributes of tree species varied from one forest stand to another;however,the tree species richness,density,and diversity peak.d at intermediate elevation on the north aspect.Findings reveal that tree composition and diversity in the montane forests of Garhwal Himalaya are influenced by both environmental(elevation and slope aspect)and soil variables(texture,water holding capacity,moisture content,available N,exchangeable P,and pH).This study will help in understanding the forest distribution across the western Himalaya,guiding the conservationists and policymak.rs in carrying out conservation-related management activities,designing the long-term monitoring studies and assessing the effect

关键词： Diversity Tree species Montane forests Soil properties Western Himalaya

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