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Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary,West Himalaya

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Journal of Mountain Science 2018年第9期15卷 1936-1949页

作者： cHANDRA Sudeep singh Ankit singh c.p. NAUTIYAL M.c. RAWAT L.S. High Altitude plant physiology Research centre(HAppRc)H.N.B.Garhwal University Srinagar Garhwal-246174UttarakhandIndia Space Applications centre (Indian Space Research Organization)Ahmedabad 380015India Govind Ballabh pant National Institute of Himalayan Environment&Sustainable Development Garhwal Unit Srinagar Garhwal-246174UttarakhandIndia

The present study was carried out in Tungnath alpine meadows of Kedarnath Wild Life Sanctuary, Western Himalaya from subalpine to upper alpine zone. A total of four summits were selected along an altitudinal gradient and sampled for detailed vegetation analysis using multi summit approach as per Global observation research initiative in alpine environments(GLORIA). Species richness, diversity, and evenness among four summits as well as the interaction between environmental variables with plant communities were assessed. Monthly mean soil temperature was calculated using data retrieved from geo-precision temperature logger in order to identify the trend of soil temperature among different season and altitudinal gradient and its implications to plant communities. Soil samples were analyzed fromeach summit by collecting randomized composite soil samples. The indirect non-metric multidimensional scaling(NMDS) and direct canonical correspondence analysis(ccA) tools of ordination techniques to determine the linkage between plant species from various sample summits and biotic/abiotic environmental gradients were used in the present study. The results of the study demonstrated increase in species richness as soil temperature increases, the ecotone representing summits were found most warm summits followed by highest species richness. Annual soil temperature increased by 1.43°c at timberline ecotone. Whereas, at upper alpine zone the soil temperature increased by 0.810 c from year 2015 to 2016. S?rensen's similarity index was found to be increased between subalpine and upper alpine zone with increase in the presence of subalpine plant species at upper alpine zone. Both the ordination tools separate the subalpine summit and their respective vegetation from summits representingtimberline ecotone and upper alpine zone. Soil p H, altitude, soil cation exchange c.p.city were found as the key abiotic drivers for distribution of plant species.

关键词： GLORIA Non-metric multidimensionalscaling (NMDS) canonical correspondence analysis(ccA) Ecotone West Himalaya

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Exploring the role of N-acetyltransferases in diseases:a focus on N-acetyltransferase 9 in neurodegeneration

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Neural Regeneration Research 2025年第10期20卷 2862-2871页

作者： prajakta Deshpande Anuradha Venkatakrishnan chimata Amit singh Department of Biology University of DaytonDaytonOHUSA premedical program University of DaytonDaytonOHUSA center for Tissue Regeneration and Engineering at Dayton(TREND) University of DaytonDaytonOHUSA Integrative Science and Engineering center University of DaytonDaytonOHUSA center for Genomic Advocacy(TcGA) Indiana State UniversityTerre HauteINUSA

Acetyltransferases,required to transfer an acetyl group on protein are highly conserved proteins that play a crucial role in development and *** acetylation is a common post-translational modification pivotal to basic cellular *** to 80%-90%of proteins are acetylated during translation,which is an irreversible process that affects protein structure,function,life,and *** this review,we have discussed the various N-acetyltransferases present in humans,their function,and how they might play a role in ***,we have focused on N-acetyltransferase 9 and its role in microtubule *** have shed light on how N-acetyltransferase 9 and acetylation of proteins can potentially play a role in neurodegenerative *** have specifically discussed the N-acetyltransferase 9-acetylation independent function and regulation of c-Jun N-terminal kinase signaling and microtubule stability during development and neurodegeneration.

关键词： acetyl-coenzyme A Alzheimer’s disease animal models cell death drosophila eye human disease c-Jun N-terminal kinase signaling N-Acetyltransferases N-acetyltransferase 9 neurodegeneration

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Viscous cosmology in holographic dark energy with Granda–Oliveros cut-off

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communications in Theoretical physics 2023年第2期75卷 144-156页

作者： Simran Kaur c.p.singh Department of Applied Mathematics Delhi Technological UniversityBawana RoadDelhi-110042India

We study the effect of bulk viscosity on holographic dark energy(HDE)with Granda–Oliveros infra-red *** focus on a generalized form of the bulk viscous coefficient which successfully describes the present-day evolution of the *** observe that the model with bulk viscosity provides an elegant description of the early and late-time evolution of the *** constrain the model through the combined observational data of the Strong Lensing System(SLS),measurements of Hubble parameter,Type Ia supernova data of pantheon sample and local H_(0)measured by *** best-fit values obtained from two different combinations of data,we estimate the present value of Hubble’s constant H_(0)=71.567-0.848+1.448and H_(0)=69.197-1.924+1.563,the deceleration parameter q_(0)=-0.535-0.016+0.016and q_(0)=-0.536-0.016+0.016,and the equation of state w_(0)=-0.690-0.010+0.010and w_(0)=-0.691-0.011+0.011,*** HDE model with bulk viscosity exhibits the phase transition from decelerated epoch to accelerated epoch.A comparison of the model with the standardΛcDM model is discussed with the statefinder and cosmographic.p.rameters.

关键词： viscosity holographic dark energy cosmology

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constraining the variable generalized chaplygin gas model in matter creation cosmology

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communications in Theoretical physics 2024年第10期76卷 119-134页

作者： Yogesh Bhardwaj c.p.singh Department of Applied Mathematics Delhi Technological UniversityBawana RoadDelhi-110042India

We explore the variable generalized chaplygin gas(VGcG)model in the theory of matter creation cosmology within the framework of a spatially homogeneous and isotropic flat Friedmann—Lemai tre—Robertson—Walker *** creation cosmology is based on reinterpretation of the energy–momentum tensor in Einstein's field *** creation corresponds to an irreversible energy flow from the gravitational field to the created matter *** variable chaplygin gas(VcG)is also studied as a particular *** use the Markov chain Monte carlo method to constrain the free parameters of three models,namely,Lambda-cold-Dark matter(ΛcDM),VGcG and VcG models with and without matter creation from the latest observational data from baryon acoustic oscillations,cosmic chronometer,type Ia supernovae(pantheon)including gamma-ray bursts,quasars and the local measurement of H_(0) from R21 *** different combinations of dataset provide a fairly tight constraint on the parameters of theΛcDM,VGcG and VcG *** present values of various cosmological parameters are obtained,which are very close to theΛcDM ***,we perform stability analysis,Bayesian evidence analysis and information criteria analysis for these models through studying the sound speed,Bayes factor,and Akaike information criteria(AIc)and Bayesian information criteria(BIc)selection *** values of sound speed for VGcG and VcG models shows that both the models are *** to AIc,it is observed that VGcG and VcG models with matter creation are supported considerably less by current observations,while BIc shows that these models are not favoured by observational data.

关键词： cosmological model matter creation chaplygin gas model dark energy

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A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： S.SAURABH R.KIRAN D.singh R.VAISH V.S.cHAUHAN School of Mechanical and Materials Engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHSDT) of plates is employed to characterize the displacement field, with the incorporation of Green-Lagrange nonlinearity. The problem is modeled using the c0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(HR), helicoidal exponential(HE), helicoidal semi-circular(HS), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

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Solution and Thermodynamic Studies on Binary and Ternary complexes of Lanthanides

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Journal of Rare Earths 2005年第4期23卷 389-396页

作者： Rajeev Kumar Udai p singh Department of chemistry Indian Institute of Technology Roorkee Roorkee-247667 IndiaDepartment of Chemistry Indian Institute of Technology Roorkee Roorkee-247667 India

The interactions of La（ Ⅲ ）, pr（ Ⅲ ）, Nd（ Ⅲ ）, Sm（ Ⅲ ）, Eu（Ⅲ）, Gd（ Ⅲ ）, Dy（ Ⅲ ）, and Yb（ Ⅲ ） with cytosine, 5-bromocytosine, 5-azacytosine and 5-flurocytosine as primary ligands （L） and guanine （A） as secondary ligand for both binary （ 1 ： 1 ） as well as ternary （ 1 ： 1 ： 1 ） systems were investigated by potentiometric equilibrium measurements at 25, 35 and 45 ℃ in aqueous solution （ionic strength, μ = 0.1 mol·dm^-3 NaNO3）. The stability constants of the binary （ 1 ： 1 ） and ternary （ 1 ： 1 ： 1 ） metal-ligand complexes follow the following order La 〈 pr 〈 Nd 〈 Sm 〈 Eu 〉 Gd 〈 Dy 〉 Yb. Results also indicate that the ternary lanthanide complexes of La（Ⅲ）, pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Dy（Ⅲ）, and Yb（ Ⅲ ） are more stable than corresponding binary lanthanide complexes. The enthalpy （△Hf^o） and entropy （△Sf^o） changes for the formation of binary and ternary complexes were calculated from temperature coefficient data. The △△Sf^o values are positive for all the metal ligand systems. The negative △△Hf^o values indicate the extra stability of the ternary complexes by the exothermic enthalpy changes （△△Sf^o = △TSf^o - △BSf^o and △△Hf^o = △THf^o - △BHf^o where △TSf^o, △THf^o and △BSf^o, △BHf^o are the entropy and enthalpy values associated with the ternary and binary complexes, respectively）. It was also proposed that the guanine is bonded to metal ions through N1/c6 = O and N7 whereas cytosine and its derivatives are bonded through N3 atoms in ternary complexes.

关键词： lanthanide solution studies cytosine thermodynamic.p.operties rare earths

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Nonlinear mixing-based terahertz emission in inclined rippled density plasmas

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chinese physics B 2023年第6期32卷 384-390页

作者： K Gopal A p singh S Divya Rajdhani college Department of Physics&ElectronicsUniversity of DelhiNew DelhiIndia computational plasma Dynamics Laboratory Rajdhani CollegeDepartment of Physics&ElectronicsUniversity of DelhiNew DelhiIndia

We propose to investigate the THz field generation using nonlinear mixing mechanism of laser beat wave with inclined rippled density *** laser pulses with frequencies(ω_(1),ω_(2)) and wave vectors(k_(1),k_(2)) co-propagate and resultant laser beat wave forms at beat frequency(ω_(1)-ω_(2)).Laser beat wave imparts a nonlinear force on the ambient electrons and pushes them outward with nonlinear velocity v_(NL).coupling of induced density perturbation and nonlinear velocity v_(NL)generates nonlinear currents at laser beat frequency that further generates electromagnetic field E_((ω_(1)-ω_(2))) in terahertz(THz)*** the present scheme,density ripples are introduced at an angle with respect to laser propagation and flat Gaussian index(f) is introduced in laser field profile that transform curved top of Gaussian field envelope into flat top field *** combined effect of flat laser pulses with inclined density ripples in plasmas shows 10-fold enhancement in THz field amplitude when flat-Gaussian index(f) varies from 1 to ***,the THz field intensifies when density ripples inclination increases upto a certain angle and then decreases.

关键词： terahertz inclined ripple flat laser laser plasma interaction

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Effects of mechanical vibration on the physical,metallurgical and mechanical properties of cast A308(LM21)aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第6期29卷 1206-1215页

作者： Siddharth Yadav S.p.Tewari J.K.singh S.c.Ram Department of Mechanical Engineering Indian Institute of Technology(BHU)Varanasi 221005India Department of Metallurgical Engineering Indian Institute of Technology(BHU)Varanasi 221005India

This study investigated the microstructure,physical,and mechanical properties of die-cast A308 alloy subjected to mechanical vibration during *** frequencies(0,20,30,40,and 50 Hz)at constant amplitude(31μm)were employed using a power amplifier as the power input device.X-ray diffraction,optical microsc.p.,and scanning electron microsc.p. were used to examine the morphological changes in the cast samples under stationary and vibratory *** features of the castings were evaluated using Image J *** average values of metallurgical features,including primaryα-Al grain size,dendrite arm spacing,average area of eutectic silicon,aspect ratio,and percentage porosity,reduced by 34%,59%,56%,22%,and 62%,respectively,at 30 Hz frequency compared with stationary *** tests of the cast samples showed that the yield strength(YS),ultimate tensile strength(UTS),percentage elongation(%EL),and microhardness(HV)increased by 8%,13%,17%,and 16%,respectively,at 30 Hz frequency compared with stationary *** fractured surface of the tensile specimens exhibited mixed-mode fracture behavior because of brittle facets,cleavage facets,ductile tearing,and dimple *** presence of small dimples showed that plastic deformation occurred before fracture.

关键词： mechanical vibration microstructures microhardness tensile strength fractography

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Laser-induced graphene-coated wearable smart textile electrodes for biopotentials signal monitoring

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Frontiers of Materials Science 2024年第1期18卷 95-111页

作者： c.M.Vidhya Yogita Maithani Sakshi Kapoor J.p.singh Department of physics Indian Institute of Technology DelhiHauz KhasNew Delhi 110016India

This paper describes how to produce a wearable dry electrode at a reasonable cost and how to use it for the monitoring of biopotentials in *** textiles in wearable technologies have made a great advancement in the health care management and living standards of *** was manufactured using the low-cost single-step process,laser ablation of polyimide,a commercial *** dispersions were made using solvent isopropyl alcohol which has low boiling point,nontoxicity,and environmental *** successive coating of the graphene dispersion on the cotton fabric to make it conductive,the sheet resistance of the resulting fabric dropped to 3% of its initial *** laser-induced graphene(LIG)cotton dry electrodes thus manufactured are comparable to Ag/Agcl wet electrodes in terms of the skin-to-electrode impedance,measuring between 78.0 and 7.2 kΩ for the frequency between 40 Hz and 1 *** LIG cotton electrode displayed a signal-to-noise ratio of 20.17 *** to its comfort,simplicity,and good performance over a longer period of time,the textile electrode appears suited for medical applications.

关键词： biopotential electrocardiogram electromyogram flexible electrode textile porous graphene

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Organic Ligand,competing cation,and pH Effects on Dissolution of Zinc in Soils

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pedosphere 2008年第1期18卷 92-101页

作者： p. LOMBNIES A. c. cHANG B. R. singh Department of plant and Environmental Sciences P. O. Box 5003 Norwegian University of Life Sciences N-1432 Aas (Norway) Departraent of Environmental Sciences University of California Riverside CA 92521 (USA)

A series of experiments were conducted to examine the interactive effects of an organic ligand,a competing cation, and pH on the dissolution of zinc (Zn) from three california soils,Maymen sandy loam,Merced clay,and Yolo clay *** concentrations of soluble Zn of the three soils were low in a background solution of ca(NO3)*** acid,a common organic ligand found in the rhizosphere,was effective in mobilizing Zn in these soils;its presence enhanced the concentration of Zn in soil solution by citrate forming a complex with *** ability of Zn to form a complex with citric acid in the soil solution was dependent on the concentration of citric acid,pH,and the concentration of the competing cation ca^(2+).The pH of the soil solution determined the extent of desorption of Zn in solid phase in the presence of citric *** amounts of Zn released from the solid phase were proportional to the concentration of citric acid and inversely proportional to the concentration of ca(NO3)2 background solution,which supplied the competing cation ca^(2+) for the formation of a complex with *** the soil suspension was spiked with Zn,the adsorption of Zn by the soils was retarded by citric acid via the formation of the soluble Zn-citrate *** dissolution of Zn in the presence of citric acid was pH dependent in both adsorption and desorption processes.

关键词： competing cation organic ligand pH soils Zn dissolution

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