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Variable stars in M37

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Research in Astronomy and Astrophysics 2018年第12期18卷 111-122页

作者： Ajaz ahmad Dar Padmakar Singh Parihar Parvej Saleh Manzoor ahmad Malik Department of Physics University of KashmirHazratbal 190006Srinagar-J&KIndia Department of Physics Islamia College of Science and CommerceHawalSrinagar-19002J&KIndia Indian Institute of Astrophysics Koramagala-560034BangaloreIndia Applied Sciences Department GowhatiUniversity of AssamIndia

The CCD photometric observations of open star cluster M37(NGC 2099) were carried out up to a limiting magnitude of V ～ 20 in both B and V filters to search for variable stars using a 2k×4k CCD and the 1.3 m telescope at the Vainu Bapu Observatory, Kavalur.A total of 314 stars were in the first observing run, out of which 60 were identified as *** out of the identified 60 variables are classified as W UMa binary *** model fitting, we used PHOEBE based on the W-D code to estimate the physical parameters of these newly detected W UMa binaries that theoretically best match the observed light curves.

关键词： techniques:photometric astronomical instrumentation methods and techniques astrometry and celestial mechanics (stars:) binaries:eclipsing

Rapid development in two-dimensional layered perovskite materials and their application in solar cells

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Chinese Chemical Letters 2018年第5期29卷 657-663页

作者： Sajjad ahmad Xin Guo State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian National Laboratory for Clean Energy Dalian 116023 China University of Chinese Academy of Sciences Beijing 100049 China

Two-dimensional （2D） layered organic-inorganic hybrid perovskite （2D PVK） materials have beenrecently developed as a novel candidate for photovoltaic application with high stability and a maximumpower conversion efficiency of 12.5%. This article summarized these newly emerging 2D PVK materialsand their uses in solar cells. The structural, physical, and chemical properties as well as the classificationof 2D PVK materials are discussed. The photovoltaic performance parameters of various 2D perovsldtesolar cells （2D PSCs） are summarized and their device stability is compared with conventional 3Dperovskite solar cells （3D PSCs）. It has been concluded that 2D PVKs show greater stability upon humidity,heat stress, and light intensity as compared to 3D analogues and act as a class of promising materials forapplication in solar cells.

关键词： Perovskite solar cells2D Perovskite materials2D Perovskite solar cellsStabilityPower conversion efficiency

REE geochemistry of core sediments of Cauvery delta,India for provenance studies

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Acta Geochimica 2020年第4期39卷 512-526页

作者： Malik Zubair ahmad Pramod Singh Department of Geology Satellite Campus LehUniversity of KashmirLehJammu&Kashmir 194104India Department of Earth Sciences School of Physical Chemical and Applied SciencesPondicherry UniversityKalapetPondicherry 605014India

The rare earth element(REE)geochemical composition of sediments from two cores were used to investigate the provenances of the Late Pleistocene to Holocene sediments of Cauvery delta,South *** chondrite-normalized REE patterns and bi-variant plots of Th/Co ***/Sc and La/Th ***/Yb indicated felsic source of ***-normalized plots of REE in both cores are almost parallel and exhibit similar fractionation ratio(Ce/Yb)_N of^***,persistence in REEs patterns implies either uniform source rocks and/or efficient homogenization of sediments during transportation and ***-normalized patterns of the samples show enrichment of light rare earth elements and flat pattern of heavy rare earth elements;such patterns imply dominance of felsic composition rocks in the ***,these samples show quite resemblance with Charnockites and Gneisses of Palani and Kodaikanal hill ***-normalized REE patterns of the Pleistocene sediments of Uttrangudi core show similar abundance,fractionation,and Eu anomaly values as of selected samples from Tertiary rocks near southwest part of the *** attribute the increased input from this region to the upliftment because of tectonic activity and lowering of sea level during the Pleistocene.

关键词： Delta sediments REEs Provenance Rainfall Relief

Magnetoelectric effect in multiferroic NdMn2O5

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Chinese Physics B 2017年第1期26卷 526-529页

作者： Syed Hamad Bukhari Javed ahmad Department of Physics Bahauddin Zakariya University Multan 60800 Pakistan

We have measured the dielectric constant for NdMn2O5 in an external magnetic field to map out the magnetoelectric phase diagram. The phase diagram corresponds well with the previously reported data of neutron diffraction and magnetic susceptibility. Our main finding is the observation of a dielectric anomaly in the low temperature phase with a strong magnetoelectric effect, which is attributed to the independent Nd^3＋ ordering. Moreover, the absence of the dielectric anomaly in the paramagnetic phase is discussed, keeping in view the exchange interaction and its dependence on the rareearth R^3＋ ionic radius.

关键词： sol–gel synthesis dielectric constant magnetoelectric effect phase transition

Monte Carlo Study of CO-NO Catalytic Surface Reaction Including CO-CO Repulsion

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Chinese Physics Letters 2006年第4期23卷 1034-1037页

作者： Waqar ahmad Musa Kaleem Baloach Physics Research Division Pakistan Institute of Nuclear Science and Technology PO Nilore Islamabad Pakista Department of Chemistry Gomal University D.I. Khan Pakistan

The CO-NO reaction on a catalytic surface is studied by using Langmuir-Hinshclwood thermal mechanism with Monte Carlo computer simulation. In this model, a novel concept of CO CO repulsion is introduced, which has experimental evidence due to the formation of dipoles when these molecules are chemisorbed on the surface. The system is investigated by applying two approaches of NO dissociation. In the first ***, NO always decomposes into N and O before adsorption on the surface, In the second case, NO adsorbs on the surface molecularly and then dissociates into N and O if a vacancy is present in its adjacent neighbourhood. The steady state reactive window （i.e. the continuous production of CO2 and N2） is obtained only with the diffusion of N-atoms on the surface, which extends with CO-CO repulsion in the first, case. Itowever, in the second case, reactive window is obtained with CO-CO repulsion alone, The reactive window width in this case is reasonably large. The first-order phase transition is eliminated in both the cases with CO-CO repulsion.

关键词： KINETIC PHASE-TRANSITIONS SQUARE LATTICE HEXAGONAL SURFACES REACTIONMODEL NITRIC-OXIDE SIMULATION MECHANISM

Deformation Kinematics of Main Central Thrust Zone(MCTZ)in the Western Himalayas

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Journal of Earth Science 2022年第2期33卷 452-461页

作者： Mohsin ahmad Ahanger Ghulam Jeelani Department of Earth Sciences University of KashmirSrinagar 190006India

The main central thrust(MCT)is one of the major thrusts in *** central Himalaya,MCT was defined as a contact between underlying Lesser Himalayan Sequence(LHS)and overlying higher Himalayan crystallines(HHC).However,in the Kashmir Himalayas,the main central thrust zone(MCTZ),shear zone associated with MCT,is overlain by Kashmir Tethyan Sequence suggesting that the MCTZ has been deformed through a mechanism different than the mechanism responsible for MCTZ evolution in other parts of the *** the present study we used structural,microfabric and kinematic analyses to investigate the deformation kinematics of *** investigation revealed that the quartz in orthogneiss mylonites of MCTZ was dynamically recrystallized by grain boundary migration(GBM)and sub-grain rotation recrystallisation(SGR)with top-toSW sense of *** mean kinematic vorticity number(W;)just above the thrust ranges from 0.72to 0.84(40%–52%pure shear component)decreasing upwards to 0.65–0.71(35%–50%pure shear component).Deformation in the MCTZ is characterized by Rxzstrain ratio varying from 2.7 to *** present study suggested that the MCTZ suffered 3%–40%vertical shortening and 3%–66%transportparallel *** results suggested that the HHC’s were not completely exhumed to the topographic surfaces in the Kashmir *** the basal decollement,i.e.,the main Himalayan thrust(MHT),the deformation continued until MCTZ reached the brittle-ductile transition where deformation mechanism changed to the brittle and the MCTZ rocks were transported to the surface through slip on brittle MCT.

关键词： kinematics mylonites finite strain mean kinematic vorticity number(Wm) general shear tectonics

Patterns and drivers of tree carbon stocks in Kashmir Himalayan forests:implications for climate change mitigation

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Ecological Processes 2022年第1期11卷 812-824页

作者： Ashaq ahmad Dar Narayanaswamy Parthasarathy Department of Ecology and Environmental Sciences School of Life SciencesPondicherry UniversityPuducherry 605014India

Background:Temperate forests are major carbon sinks because of their high storage potential and low decomposi-tion *** quantified tree carbon(TC)storage from 143 plots distributed across three major forest types of Kashmir Himalaya,relative to differences in ecological *** regression and Random Forest(RF)analysis were used to examine the distribution of TC stock along ecological gradients and recognize the role of driving factors on TC ***:Among the three forest types,sub-alpine(SA)forest was the primary TC sink,accounting for 228.73 t ha^(−1)of carbon,followed by mixed conifer(MC;181.29 t C ha^(−1))and blue pine(BP;133.04 t C ha^(−1))*** distribution of TC stocks among the three forest types differed significantly(χ^(2)=18.87;P=0.000).Relative carbon stock analysis demonstrated that Abies pindrow and Pinus wallichiana accounted 91%of TC stocks across the *** area,mean diameter at breast height(DBH),elevation,disturbance and precipitation had significant effects on TC stocks in bivariate regression *** RF model explained 86%of the variation;basal area interpreted 30.15%,followed by mean DBH(17.96%),disturbance complex(10.64%),precipitation(8.00%)and elevation(7.34%).Conclusions:Kashmir Himalayan forests are significant carbon sinks as they store a substantial quantum of carbon in *** carbon,an essential climatic indicator,is determined by a complex interaction of other ecological vari-ables,particularly stand structural *** study provides insights into the role of these natural forests in climate change mitigation and in REDD+/national commitments to offset the carbon.

关键词： Carbon stock Climate change Coniferous forest Disturbance Kashmir Himalaya Stand structure

Magnetic metal organic framework for pre-concentration of ampicillin from cow milk samples

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Journal of Pharmaceutical Analysis 2020年第4期10卷 365-375页

作者： ahmad Reza Bagheri Mehrorang Ghaedi Chemistry Department Yasouj UniversityYasouj75918-74831Iran

The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework(MMOF)and subsequently its application as sorbent for ultrasound assisted magnetic solid phase extraction(UAMSPE)of ampicillin(AMP)from cow milk samples prior to high performance liquid chromatography-Ultraviolet(HPLC-UV)*** of prepared MMOF were fully investigated by different techniques which showed the exclusive properties of proposed sorbent in terms of proper functionality,desirable magnetic property and also high specific surface *** influential factors on extraction recovery including sorbent dosage,ultrasonic time,washing solvent volume and eluent solvent volume were assessed using central composite design(CCD)based response surface methodology(RSM)as an operative and powerful optimization *** is the first report for determination of AMP using *** proposed method addressed some drawbacks of other methods and sorbents for determination of *** presented method decreases the extraction time(4 min)and also enhances adsorption capacity(250 mg/g).Moreover,the magnetic property of presented sorbent(15 emu/g)accelerates the extraction process which does not need filtration,centrifuge and precipitation *** the optimized conditions,the proposed method is applicable for linear range of 1.0-5000.0 μg/L with detection limit of 0.29 μg/L,satisfactory recoveries(≥95.0%)and acceptable repeatability(RSD less than 4.0%).The present study indicates highly promising perspectives of MMOF for highly effective analysis of AMP in complicated matrices.

关键词： Magnetic metal organic framework Ultrasound assisted magnetic solid phase extraction Ampicillin Cow milk samples

Computer Oriented Numerical Scheme for Solving Engineering Problems

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Computer Systems Science & Engineering 2022年第8期42卷 689-701页

作者： Mudassir Shams Naila Rafiq Nasreen Kausar Nazir ahmad Mir ahmad Alalyani Department of Mathematica and Statistics Riphah International UniversityI-14Islamabad 44000Pakistan Department of Mathematics NUMLIslamabad 44000Pakistan Department of Mathematics Yildiz Technical UniversityFaculty of Arts and ScienceEsenler34210IstanbulTurkey Department of Mathematics Faculty of Science and Arts in ALmandaqAl-Baha UniversityAl-BahaSaudi Arabia

In this study,we construct a family of single root finding method of optimal order four and then generalize this family for estimating of all roots of non-linear equation *** analysis proves that the local order of convergence is four in case of single root finding iterative method and six for simultaneous determination of all roots of non-linear *** non-linear equations are taken from physics,chemistry and engineering to present the performance and efficiency of the newly constructed *** real world applications are taken from fluid mechanics,i.e.,fluid permeability in biogels and biomedical engineering which includes blood Rheology-Model which as an intermediate result give some nonlinear *** non-linear equations are then solved using newly developed simultaneous iterative *** developed simultaneous iterative schemes reach to exact values on initial guessed values within given tolerance,using very less number of function evaluations in each *** convergence order of single root finding method is computed using *** computational order of convergence,CPU-time,absolute residuals errors are calculated to elaborate the efficiency,robustness and authentication of the iterative simultaneous method in its domain.

关键词： Biomedical engineering convergence order iterative method CPU-time simultaneous method