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Relaxation of Mechanical stress in Poly(vinyl alcohol) Cryogels of Different Compositions

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Chinese Journal of Polymer science 2023年第3期41卷 442-447,I0010页

作者： Vladimir n.Manzhai Maria s.Fufaeva Ekaterina s.Kashlach Institute of Petroleum Chemistry of the siberian Branch of the Russian Academy of sciences Tomsk 634055Russia

The study presents the experimental results of measurements of the relaxation time of cryogels formed from various colloid-dispersed systems based on a poly(vinyl alcohol) aqueous *** is shown that the value of relaxation time,which characterizes the relationship between the viscosity and elasticity of real bodies,describes the rheological properties of materials more objectively than the traditional assessment of their physical and mechanical characteristics only by the elasticity modulus of the samples.

关键词： Cryogel Relaxation processes Viscoelasticity Rheological properties

f(T,B)gravity with statistically fitting of H(z)

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Communications in Theoretical Physics 2023年第9期75卷 79-90页

作者： s H shekh n Myrzakulov A Bouali A Pradhan Department of Mathematics S.P.M.Science and Gilani ArtsCommerce CollegeGhatanjiYavatmalMaharashtra 445301India L.n.Gumilyov Eurasian national University Astana 010008Kazakhstan Ratbay Myrzakulov Eurasian International Center for Theoretical Physics Astana010009Kazakhstan Laboratory of Physics of Matter and Radiation Mohammed I UniversityBP 717OujdaMorocco Centre for Cosmology Astrophysics and Space Science(CCASS)GLA UniversityMathura-281406Uttar PradeshIndia

some recent developments(accelerated expansion)in the Universe cannot be explained by the conventional formulation of general *** apply the recently proposed f(T,B)gravity to investigate the accelerated expansion of the *** parametrizing the Hubble parameter and estimating the best fit values of the model parameters b_(0),b_(1),and b_(2)imposed from supernovae type la,Cosmic Microwave Background,B aryon Acoustic Oscillation,and Hubble data using the Markov Chain Monte Carlo method,we propose a method to determine the precise solutions to the field *** then observe that the model appears to be in good agreement with the observations.A change from the deceleration to the acceleration phase of the Universe is shown by the evolution of the deceleration *** addition,we investigate the behavior of the statefinder analysis,equation of state(Eos)parameters,along with the energy ***,to discuss other cosmological parameters,we consider some wellknown f(T,B)gravity models,specifically,f(T,B)=aT^(b)+cB^(d).Lastly,we find that the considered f(T,B)gravity models predict that the present Universe is accelerating and the Eos parameter behaves like the ACDM model.

关键词： isotropic homogeneous space-time f(T,B)gravity statistical fitting of H(z)data cosmology

Early Phases of star Formation: Testing Chemical Tools

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Research in Astronomy and Astrophysics 2024年第1期24卷 96-118页

作者： n.C.Martinez s.Paron COnICET-Universidad de Buenos Aires.Instituto de Astronomía y Física del Espacio Ciudad Universitaria(C1428EGA)Ciudad Autónoma de Buenos AiresArgentina

star-forming processes strongly influence the IsM ***,many high-quality databases are available at millimeter *** them,it is possible to carry out studies that review and deepen previous *** these studies involve large samples of sources,it is preferred to use direct tools to study the molecular *** the aim of testing these tools such as the use of the HCn/HnC ratio as a thermometer,and the use of H^(13)CO^(+),HC_(3)n,n_(2)H^(+) and C_(2)H as "chemical clocks," we present a molecular line study toward 55 sources representing massive young stellar objects at different evolutionary stages:infrared dark clouds(IRDCs),highmass protostellar objects(HMPOs),hot molecular cores(HMCs) and ultracompact H II *** found that the use of the HCn/HnC ratio as a universal thermometer in the IsM should be taken with care because the HCn optical depth is a big issue that can affect the ***,this tool should be utilized only after a careful analysis of the HCn spectrum,checking that no line,neither the main nor the hyperfine ones,presents absorption *** point out that the analysis of the emission of H^(13)CO^(+),HC_(3)n,n_(2)H^(+) and C_(2)H could be useful to trace and distinguish regions among IRDCs,HMPOs and *** molecular line widths of these four species increase from the IRDC to the HMC stage,which can be a consequence of the gas dynamics related to the starforming processes taking place in the molecular *** results not only contribute with more statistics,acting as a probe of such chemical tools,useful to obtain information in large samples of sources,but also complement previous works through the analysis of other types of sources.

关键词： stars:formation IsM:molecules IsM:clouds

Chloride binding and time-dependent surface chloride content models for fly ash concrete

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Frontiers of structural and Civil Engineering 2016年第1期10卷 112-120页

作者： s. MUTHULInGAM B. n. RAO Department of Civil Engineering SSN College of Engineering Kalavakkam 603 110 India structural Engineering Division Department of Civil Engineering Indian Institute of Technology Madras Chennai 600 036 India

Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. such environments can be attributed to the presence of seawater, deicing or sea-salts, which have high concentrations of chloride ion. Chloride ingress into concrete, essential for inducing rebar corrosion, is a complex interaction between many physical and chemical processes. The current study proposes two chloride ingress parameter models for fly ash concrete, namely： 1） surface chloride content under tidal exposure condition; and 2） chloride binding. First, inconsistencies in surface chloride content and chloride binding models reported in literature, due to them not being in line with past research studies, are pointed out. secondly, to avoid such inconsistencies, surface chloride content and chloride binding models for fly ash concrete are proposed based upon the experimental work done by other researchers. It is observed that, proposed models are simple, consistent and in line with past research studies reported in literature.

关键词： binding isotherms chloride ingress concrete fly ash surface chloride content

Comprehensive investigation of stress intensity factors in rotating disks containing three-dimensional semi-elliptical cracks

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Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1565-1578页

作者： M.FAKOOR s.M.n.GHOREIsHI Faculty of new sciences and Technologies University of Tehran Tehran 14395-1561 Iran

Initiation and propagation of cracks in rotating disks may cause catastrophic failures. Therefore, determination of fracture parameters under different working con- ditions is an essential issue. In this paper, a comprehensive study of stress intensity factors （sIFs） in rotating disks containing three-dimensional （3D） semi-elliptical cracks subjected to different working conditions is carried out. The effects of mechanical prop- erties, rotational velocity, and orientation of cracks on sIFs in rotating disks under cen- trifugal loading are investigated. Also, the effects of using composite patches to reduce sIFs in rotating disks are studied. The effects of patching design variables such as mechanical properties, thickness, and ply angle are investigated separately. The modeling and analytical procedure are verified in comparison with previously reported results in the literature.

关键词： stress intensity factor (sIF) semi-elliptical crack rotating disk finite ele-ment analysis (FEA)

Multi-exponential model to describe pressure-dependent P-and s-wave velocities and its use to estimate the crack aspect ratio

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第2期14卷 385-395页

作者： Mihály Dobróka norbert Péter szabó Tünde Edit Dobróka Mátyás Krisztián Baracza Department of Geophysics University of MiskolcMiskolc-Egyetemváros3515Hungary MTA-ME Geoengineering Research Group University of MiskolcMiskolc-Egyetemváros3515Hungary Research Institute of Applied Earth sciences University of MiskolcMiskolc-Egyetemváros3515Hungary

We present new quantitative model describing the pressure dependence of acoustic P-and s-wave *** that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand s-waves)velocity-pressure *** estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and s-wave velocity *** is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are *** the number of exponential terms leads to highly nonlinear ill-posed inverse *** to this reason,we develop the spectral inversion method(sIM)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as *** characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and s-wave velocity *** characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical *** gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.

关键词： Multi-exponential rock physical model spectral inversion method(sIM) Crack aspect ratio Characteristic pressures

comseedling growth of five tropical dry forest tree species in relation to light and nitrogen gradients

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Journal of Plant Ecology 2014年第3期7卷 250-263页

作者： s.n.Tripathi A.s.Raghubanshi Ecosystems Analysis Laboratory Department of BotanyBanaras Hindu UniversityVaranasiUttar Pradesh 221005India Deen Dayal Upadhyaya College University of DelhiShivaji MargKarampuraNew Delhi 110015India Institute of Environment and sustainable Development Banaras Hindu UniversityVaranasiUttar Pradesh 221005India

Aims Increasing anthropogenic nitrogen(n)deposition has been claimed to induce changes in species composition and community dynamics.A greenhouse experiment was conducted to examine the effect of increased n availability on growth and functional attributes of seedlings of five tree species with different life history characteristics under varying *** following questions have been addressed:(i)how do the pioneer and non-pioneer species respond in absolute growth and relative growth rate(RGR)to the interaction of light and nitrogen?(ii)how does the interaction between irradiance and nitrogen availability modulate growth attributes(*** attributes)?(iii)is there any variation in growth responses between leguminous and non-leguminous species along the light and nitrogen gradients?Methods seedlings of five tree species(Acacia catechu,Bridelia retusa,Dalbergia sissoo,Lagerstroemia parviflora and Terminalia arjuna)were subjected to twelve combinations of irradiance and n *** growth traits,including height(HT),basal area(BA),whole plant dry biomass(MD),leaf mass per unit area(LMA),leaf area ratio(LAR),net assimilation rate(nAR),RGR,biomass fractions,root-toshoot ratio(R:s)and leaf nitrogen content,were studied to analyse intra-and inter-specific responses to interacting light and n *** Findings significant interactions for irradiance and n availability for majority of growth attributes indicates that growth and biomass allocation of seedlings were more responsive to n availability under high ***,species responded differentially to n addition and they did not follow successional *** growers(***,a shade-tolerant species and ***,a light demander)exhibited greater response to n enrichment than the fast growers(***,*** and ***).However,n-mediated increment in growth traits was greater in non-legumes(***,*** and ***)compared with that of legumes(*** and D

关键词： tropical dry forest irradiance nitrogen biomass allocation relative growth rate net assimilation rate

structural and photoluminescence properties of La3+ doped CdO nanophosphors synthesised via green mediated solution combustion route

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Journal of Rare Earths 2019年第9期37卷 916-923,I0001页

作者： M.s. Geetha H.n. shivananjaiah Vijaya Composite College Bangalore560 003India Government science College Nrupatunga RoadBangalore 560 001India

This paper reports a facile environmentally safe green combustion synthesis method of La3+doped CdO nanoparticles(nPs)using different concentrations of Aloe vera(A.V)gel as combustible *** crystallite size obtained using PXRD pattern is found to be 12-22 *** structural analysis was further analysed by Rietveld refinement *** X-ray photoelectron spectroscopy(XPs)analysis reveals the presence of two electronic states of CdO around 400 and 411 eV attributed to Cd 3 d3/2 and 3 d3/2,*** photoluminescence(PL)studies were carried upon 350 nm excitation *** PL emission spectra are found to have two prominent peaks centered at 410 and 510 nm and are attributed to 5D3→7F1 and 5D1→7F0 transitions,*** Commission International de l’Eclairage(CIE)chromaticity diagram reveals blue-green color *** correlation color temperature(CCT)value is found to be around^9793 *** obtained results suggest that the product is quite useful for cool light emitting diode applications when doping concentration is 2 mol%.

关键词： Green synthesis nanostructures Photoluminescence Judd-ofelt Rare earths CdO

Comparative assessment of mechanical and chemical fluid diversion techniques during hydraulic fracturing in horizontal wells

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Petroleum science 2023年第6期20卷 3582-3597页

作者： Maunish s.shah subhash n.shah Drilling Cementingand Stimulation Research CenterDepartment of Petroleum EngineeringSchool of Energy TechnologyPandit Deendayal Energy UniversityRaisanGandhinagarGujaratIndia Mewbourne school of Petroleum and Geological Engineering The University of OklahomaNormanOKUSA

The application of fluid diversion during hydraulic fracturing is an evolving technology and has become popular amongst E&P operators over the past few *** primary objective of the fluid diversion is to improve hydraulic fracturing treatment by increasing stimulated reservoir volume and improving hydrocarbon *** is possible by achieving any of the following objectives:creating uniform distribution of treatment slurry within the target zone;treating unstimulated and under-stimulated zones;or by increasing fracture density by creating a complex fracture *** fluid diversion application is also helpful in decreasing the number of stages(by increasing stage length)for multi-stage plug-n-perf(PnP)fracturing *** is also applied to prevent fracture-driven interactions between adjacent wells,which is currently a major issue,especially in *** addition,for successful refracturing treatment,the diverter application is essential for isolating the existing fractures and redirecting the treatment slurry to the desired unstimulated *** diversion methods can be broadly categorized into the mechanical and chemical *** established mechanical diversion techniques are frac plugs,expandable casing patches,expandable liners,swellable packers,straddle packer assembly,sand plugs,frac sleeves,perforation ball sealers,and limited entry *** different chemical diversion techniques are particulates,fibers,gels,surfactants,perforation pods,and composite *** paper describes the current status of established mechanical and chemical diverter technologies and examines their comparative advantages and *** techniques are suitable for diverter application,but the technique is selected based on the desired objective and conditions of the wellbore and *** general guidelines for selecting diversion techniques and operational considerations are also provided in the *** diagnosis of diversion treatme

关键词： Fluid diversion Diverter Diverting agents Multi-stage fracturing Hydraulic fracturing Horizontal well