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Plasmonic enhancement of upconver.ion emission in Ag@NaYF4:Er.3+/Yb^3+phosphor

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Jour.al of r.r. Ear.hs 2018年第9期36卷 903-910页

作者： S.k.Maur.a S.r.tiwari A.k.mar.k.k.mar Optical Mater.als and Bio-imaging r.sear.h Labor.tor. Department of Applied PhysicsIndian Institute of Technology(Indian School of Mines)Dhanhad-826004India

In this ar.icle upconver.ion luminescence of silver.nanopar.icles（AgNPs） coated NaYF4：Er.＋/Yb3＋phosphor.nano-par.icles was *** pr.par.d samples wer. char.cter.zed thr.ugh var.ous *** sur.ace plasmon band is obser.ed for.pr.par.d AgNPs by analyzing UV-vis measur.ments and is used to enhance the upconver.ion *** the upconver.ion measur.ment the emission bands ar. obser.ed at 522,546,and 656 nm cor.esponding to the 2 H11/2→ 4115/2,4 S3/2→4 I15/2and 4 F9/2→4 I15/2 levels,*** upconver.ion emission intensity of the above bands is found to enhance for.sample containing 1 mmol *** time of 4 S3/2 and 4F9/2 levels is found to decr.ase on coating of AgNPs and hence intensity enhancement is assumed due to the sur.ace plasmon r.sonance（SPr. effect.

关键词： Upconver.ion phosphor Sur.ace plasmon r.sonance Decay time analysis CIE diagr.m r.r. ear.hs

The cor.elation between fr.ction coefficient and ar.al topogr.phy par.meter. for.AISI 304 steel sliding against AISI 52100 steel

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Fr.ction 2021年第1期9卷 41-60页

作者： Deepak.k.Pr.JAPATI Mayank.tiwari Depar.ment of Mechanical Engineer.ng Indian Institute of TechnologyPatna 801103India

Dr. wear.exper.ments pr.vide an insight detail on how sever.ly contacting sur.aces change under.unlubr.cated sliding condition. The theor. of dr. sliding wear.is used for.under.tanding mixed-lubr.cation r.gime in which asper.ty inter.ctions play a significant r.le in contr.lling of the fr.ction coefficient(f). The pur.ose of this wor. is to study the tr.bological behavior.of AISI 304 steel in contact with AISI 52100 steel dur.ng wear. Both mater.als ar. used in r.lling element bear.ngs commanly. Exper.ments ar. car.ied out using a pin-on-disc tr.bometer.under.dr. fr.ction condition. The ar.al(thr.e dimensional, 3D) topogr.phy par.meter. ar. measur.d using a 3D white light inter.er.meter.WLI) with a 10× objective. After.wear.tests, wear.mechanisms ar. analyzed utilizing scanning electr.n micr.scope(SEM). Factor.al design with custom r.sponse sur.ace design(C-r.D) is used to study the mutual effect of load and speed on r.sponse var.ables such as f and topogr.phy par.meter.. It is obser.ed that the r.ot mean squar. r.ughness(S_(q)) decr.ases with an incr.ase in sliding time. Within the r.nge of sliding time, S_(q) decr.ases with an incr.ase in the nor.al load. Within the r.nge of sliding speed and nor.al load, it is found that S_(q), mean summit cur.atur.(S_(sc)), and r.ot mean squar. slope(S_(dq)) ar. positively cor.elated with f. Wher.as, negative cor.elation is found between f and cor.elation length(Sal), mean summit r.dius(r., and cor. r.ughness depth(S_(k.).

关键词： fr.ction coefficient(f) ar.al topogr.phy par.meter. factor.al design non-contact optical pr.filer scanning electr.n micr.scope(SEM)

r.gener.tion of tr.e species in the sub-tr.pical for.st of Alak.anda Valley, Gar.wal Himalaya, India

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For.str. Studies in China 2013年第2期15卷 89-97页

作者： r.dha BALLABHA J. k. tiwari P. tiwari Depar.ment of Botany and Micr.biology HNB Garhwal UniversitySrinagar Garhwal 246174 Uttarakhand India

We studied the r.gener.tion of tr.e species in the sub-tr.pical for.st of Alak.anda Valley in Gar.wal Himalaya, India. The over.ll r.gener.tion status was fair.y good in the study ar.a. Seedling density r.nged between 520 and 1,240 seedlings per.ha while the density of saplings var.ed 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 r.xbur.hfi and r.maining thr.e sites viz., C1, D1 and D2 r.pr.sented the highest number.of seedlings （240-400 per.ha） and saplings （200-240 per.ha） for.Anogeissus latifolius. The DBH class distr.bution of the tr.e species r.vealed that the highest number.of individuals was concentr.ted in the lower.diameter.classes while smallest number. wer. found in the higher.diameter.classes. Species such as Acacia catechu, Anogeissus latifolius, Dalber.ia sissoo, Engelhar.tia spicata, Lannea cor.mandelica, Mallotus philippensis and Pinus r.xbur.hii have the lar.- est number.of saplings and seedlings in the lower.DBH classes, suggesting that they have good r.gener.tion potential. Other.spec es such as Aegle mar.elos, Bauhinia var.egata, Bombax ceiba, Cassia fistula, Er.thr.na var.egata, Haldinia ：cor.ifolia, Mangifer. indica, Ougeinia oojeinensis, Phyllanthus emblica, Syzygium cumini, Ter.inalia alata and Toona hexandr. have either.no or.ver. small number.of saplings in the lower.DBH classes which indicates that the status of these species implies poor.r.gener.tion.

关键词： Gar.wal Himalaya distur.ances r.gener.tion tr.e species

Har.ful algal blooms in fr.sh and mar.ne water.systems： The r.le of toxin pr.ducing phytoplank.on

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Inter.ational Jour.al of Biomathematics 2016年第3期9卷 191-210页

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

In this paper. we have investigated a model with thr.e inter.cting species： non-toxic phy- toplank.on, toxic phytoplank.on and zooplank.on with Holling type II and III functional r.sponses over.the space and time. The r.le of toxin pr.ducing phytoplank.on （TPP） has been studied. We have pr.sented the theor.tical analysis of patter. for.ation in spatially distr.buted population with local diffusion. The paper.highlights the heter.- geneity of HABs over.space and time. The choice of par.meter.values and the functional r.sponse is impor.ant to study the effect of TPP, also it would depend mor. on the non- linear.ty of the system. With the help of numer.cal simulations, we have obser.ed the spatial and spatiotempor.l patter.s for.plank.on system. This study demonstr.tes that TPP plays an impor.ant r.le in contr.lling the dynamics. We have obser.ed that pr.y＇s anti-pr.dator.effor.s pr.mote pr.dator.switching. It has been found that high pr.dation of TPP helps for.the coexistence of toxic, non-toxic phytoplank.on and zooplank.on population.

关键词： Plank.on har.ful algal bloom toxin pr.ducing phytoplank.on spatiotem-por.l patter..

MODELING THE r.LE OF DISSOLVED OXYGEN- DEPENDENT BACTEr.A ON BIODEGr.DATION OF Or.ANIC POLLUTANTS

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Inter.ational Jour.al of Biomathematics 2014年第1期7卷 145-160页

作者： J. B. SHUk.A ASHISH GOYAL P. k. tiwari A. k. MISr. BIT BIIFRED Bhabha Group of Institutions Kanpur (Rural) 209204 India The Univer.ity of New South Wales Sydney NSW 2052 Australia Depar.ment of Mathematics BHU Varanasi India

In this paper. a nonlinear.mathematical model is pr.posed and analyzed to study the r.le of dissolved oxygen （DO）-dependent bacter.a on biodegr.dation of one or.two or.anic pollutant（s） in a water.body. In the case of two or.anic pollutant（s）, it is assumed that the one is fast degr.ding and the other.is slow degr.ding and both ar. dischar.ed into the water.body fr.m outside with constant r.tes. The density of bacter.a is assumed to follow logistic model and its gr.wth incr.ases due to biodegr.dation of one or.two or.anic pollutant（s） as well as with the incr.ase in the concentr.tion of DO. The model is analyzed using the stability theor. of differ.ntial equations and by simulation. The model analysis shows that the concentr.tion（s） of one or.both or.anic pollutant（s） decr.ase（s） as the density of bacter.a incr.ases. It is noted that for.ver. lar.e density of bacter.a, the or.anic pollutant（s） may be r.moved ahnost completely fr.m the water.body. It is found that simulation analysis confir.s the analytical r.sults. The r.sults obtained in this paper.ar. in line with the exper.mental obser.ations published in liter.tur..

关键词： Or.anic pollutants bacter.a dissolved oxygen mathematical model.

Mechanical pr.per.ies and ther.al conductivity of pr.stine and functionalized car.on nanotube r.infor.ed metallic glass composites:A molecular.dynamics appr.ach

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

作者： Sumit Shar.a S.k.tiwari Sagar.Shak.a Depar.ment of Mechanical Engineer.ng Dr.B.R.Ambedkar National Institute of TechnologyJalandharIndia

This wor. uses the molecular.dynamics appr.ach to study the effects of functionalization of car.on nanotubes(CNTs)on the mechanical pr.per.ies of Cu64Zr.6 metallic glass(MG).Thr.e types of functional gr.ups,car.oxylic,vinyl and ester.wer. *** effect of CNT volume fr.ction(Vf)and the number.of functional gr.ups attached to CNT,on the mechanical pr.per.ies and ther.al conductivity of CNT-MG composites was analysed using Biovia Mater.als *** lower.values of Vf(fr.m 0 to 5%),the per.entage incr.ase in Young’s modulus was appr.ximately 66%.As the value of Vf was incr.ased fur.her.fr.m 5 to 12%),the r.te of incr.ase in Young’s modulus was r.duced to 16%.The ther.al conductivity was found to incr.ase fr.m 1.52 W/mk.at Vf?0%to 5.88 W/mk.at Vf?12%,thus giving an incr.ase of appr.ximately 286%.Functionalization of SWCNT r.duced the ther.al conductivity of the SWCNT-MG composites.

关键词： Molecular.dynamics Car.on nanotube Metallic glass Mechanical pr.per.ies Ther.al conductivity

Luminescence and ESr.Studies of CaS：Dy Phosphor

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Chinese Physics Letter. 2005年第12期22卷 3182-3185页

作者： Vijay Singh 朱俊杰 T. k. Gundu r.o Manoj tiwari 潘宏程 Depar.ment of Chemistr. Key Laboratory of Analytical Chemistry for Life Science Nanjing University Nanjing 210093 r.gional Sophisticated Instr.mentation Centr. IIT Powai Mumbai-400 076 India Depar.ment of Post Gr.duate Studies and Research in Physics Bhoj College Kotra Bhopal-462 003 India

CaS phosphor.activated with Dy ions is pr.par.d by the solid-state diffusion method. The phosphor.is char.cter.zed by x-r.y powder.diffr.ction, ther.ogr.vimetr.c analysis and photoiuminescence. Defect centr.s for.ed in CaS：Dy ar. studied using the technique of electr.n spin r.sonance. The ther.oluminescence glow cur.e shows peak. at ar.und 117℃ and 345℃. Ir.adiated CaS：Dy exhibits ESr.lines due to defect centr.s. The ther.al annealing behaviour.of one of the defect centr.s appear. to cor.elate with the TL peak. at 117℃ and 345℃. This centr. is char.cter.zed by an isotr.pic g-value of 2.0035 and is assigned to an F^＋ centr..

关键词： ELECTr.N SPIN r.SONANCE CALCIUM SULFIDE THIN-FILMS CATHODOLUMINESCENCE PAr.METEr. EU

Tr.e species composition and diver.ity in montane for.sts of Gar.wal Himalaya in r.lation to envir.nmental and soil pr.per.ies

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Jour.al of Mountain Science 2020年第12期17卷 3097-3111页

作者： Dinesh Singh r.WAT P.tiwari Sudipta k.mar.DAS J.k.tiwari Depar.ment of Botany&Micr.biology HNB Garhwal UniversitySrinagar(Garhwal)-246174UttarakhandIndia Centr.l National Her.ar.um Botanical Survey of IndiaHowrah-711103West BengalIndia

The montane for.sts of Gar.wal Himalaya wer. investigated for.tr.e species composition and diver.ity in r.lation to envir.nmental and edaphic var.ables.A str.tified r.ndom sampling appr.ach was adopted to collect the field data fr.m each for.st.A total of 39 tr.e species belonging to 31 gener. and 23 families wer. r.cor.ed fr.m the sampling ar.a(6 for.st stands ×10 plots in each).Laur.ceae with 5 species was the lar.est family while Quer.us(4 species) emer.ed as the lar.est ***-ar.a cur.e(asymptote) pr.dicted mor. species than the obser.ed number.of *** analysis has shown that the two Abies pindr.w dominant for.st stands had the highest similar.ty in tr.e species *** tr.e stem density r.nged fr.m 540-1170 ha-1,basal ar.a 23.01-55.94 m^2 ha-1,ShannonWiener.diver.ity index 1.69-2.49,evenness index0.42-0.74,beta diver.ity 0.40-0.82 and similar.ty index 0.17-0.54 in the six studied ***-way indicator.species analysis(TWINSPAN) identified four.distinct tr.e communities in the study ar.a with Daphniphyllum himalayense,Abies pindr.w,Quer.us oblongata,and Pinus r.xbur.hii as indicator.species of cor.esponding *** cor.espondence analysis(CCA) ascer.ained the TWINSPAN r.sults and r.vealed the r.lation of tr.e species with envir.nmental and edaphic *** phytosociological attr.butes of tr.e species var.ed fr.m one for.st stand to another.however.the tr.e species r.chness,density,and diver.ity peak.d at inter.ediate elevation on the nor.h *** r.veal that tr.e composition and diver.ity in the montane for.sts of Gar.wal Himalaya ar. influenced by both envir.nmental(elevation and slope aspect)and soil var.ables(textur.,water.holding capacity,moistur. content,available N,exchangeable P,and pH).This study will help in under.tanding the for.st distr.bution acr.ss the wester. Himalaya,guiding the conser.ationists and policymak.r. in car.ying out conser.ation-r.lated management activities,designing the long-

关键词： Diver.ity Tr.e species Montane for.sts Soil pr.per.ies Wester. Himalaya

Motion thr.ugh spher.cal dr.plet with non-homogenous por.us layer.in spher.cal container

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Applied Mathematics and Mechanics(English Edition) 2020年第7期41卷 1069-1082页

作者： P.k.YADAV A.tiwari P.SINGH Depar.ment of Mathematics Motilal Nehru National Institute of Technology AllahabadPrayagraj 211004India Depar.ment of Mathematics Birla Institute of Technology SciencePilani 333031Rajasthan Depar.ment of Mathematics National Institute of Technology PatnaPatna 800005India

The pr.blem of the cr.eping flow thr.ugh a spher.cal dr.plet with a non-homogenous por.us layer.in a spher.cal container.has been studied ***’s model for.the flow inside the por.us annular.r.gion and the Stok.s equation for.the flow inside the spher.cal cavity and container.ar. used to analyze the *** dr.g for.e is exer.ed on the por.us spher.cal par.icles enclosing a cavity,and the hydr.dynamic per.eability of the spher.cal dr.plet with a non-homogeneous por.us layer.is *** is placed on the spatially var.ing per.eability of a por.us medium,which is not cover.d in all the pr.vious wor.s r.lated to spher.cal *** var.ation of hydr.dynamic per.eability and the wall effect with r.spect to var.ous flow par.meter. ar. pr.sented and discussed *** str.amlines ar. pr.sented to discuss the k.nematics of the *** pr.vious r.sults for.hydr.dynamic per.eability and dr.g for.es have been ver.fied as special limiting cases.

关键词： non-homogenous por.us medium Stok.s equation Dar.y’s law per.e-ability par.meter wall effect