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Tensile deformation of fine-grained mg at 4K,78K and 298K

Journal of magnesium and Alloys 2024年第6期12卷 2534-2556页

作者： m.Walag A.Kula P.Noga T.Tokarski g.Cios m.Niewczas AgH University of Krakow Faculty of Non-Ferrous MetalsKrakowPoland AgH University of Krakow Academic Centre for Materials and NanotechnologyKrakowPoland materials Science and Engineering McMaster UniversityHamiltonCanada

The impact of grain size, ranging from 0.9 μm to 9 μm, on the mechanical properties of commercially pure mg is investigated at temperatures of 4K, 78K, and 298K. The mechanisms governing plastic flow are influenced by both grain size and temperature. At 4K and 78K, dominant deformation modes in mg involve dislocation glide and extension twinning, regardless of grain size. The interactions between basal and non-basal dislocations and dislocations with grain boundaries promote an unusually high rate of work hardening in the plastic regime, leading to premature failure. The yield stress follows the Hall-Petch relationship σy~ k/√d, with the slope k increasing with decreasing temperature. At 298K, in addition to dislocation glide and twinning, grain boundary sliding(gBS) becomes significant in samples with grain sizes below 3 μm, considerably enhancing the material's deformability. gBS activation provides an additional recovery mechanism for dislocations accumulating at grain boundaries, facilitating their absorption during sliding and rotation. Analysis of σ Θ relationship suggests that the basal slip is the dominant dislocation mode in mg at 298K. Decreasing grain size suppresses dislocation activity and twinning and increases gBS, resulting in lower Θ and σ Θ values. Suppressing conventional deformation modes coupled with enhanced gBS yields stress softening, breaking down the Hall-Petch relationship in mg below 3 μm grain size, leading to an inverse Hall-Petch behaviour. The work reports new data on the strength, ductility, work hardening and fracture behaviour, and their variations with mg grain size across different temperature regimes.

关键词： Polycrystalline mg mechanical properties Deformation mechanisms Work-hardening Texture evolution Cryogenic temperatures Hall-Petch relationship

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modeling mitochondria,where are the numbers?

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Neural Regeneration Research 2024年第7期19卷 1435-1436页

作者： Adrian m.Davies Alan g.Holt University Center Shrewsbury ShrewsburyShropshireUK

models and simulations are particularly useful for exploring ideas and concepts in the biological sciences that are expe rimentally *** silico methods are also gaining acceptance with regulatory authorities as an alte... 详细信息

关键词： eliminate authorities acceptance

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Dynamics of a rotating ring-stiffened sandwich conical shell with an auxetic honeycomb core

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Applied mathematics and mechanics(English Edition) 2024年第6期45卷 963-982页

作者： S.JAHANgiRi A.gHORBANPOUR ARANi z.KHODDAmi mARAgHi Department of Solid mechanics Faculty of Mechanical EngineeringUniversity of KashanKashan ***Iran Faculty of Engineering Mahallat Institute of Higher EducationMahallat ***Iran

The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is *** shell is modeled utilizing the first-order shear deformation theory(FSDT)incorporating the relative,centripetal,and Coriolis accelerations alongside the initial hoop tension created by the *** governing equations,compatibility conditions,and boundary conditions are attained using Hamilton’s *** trigonometric functions,an analytical solution is derived in the circumferential direction,and a numerical one is presented in the meridional direction via the differential quadrature method(DQm).The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are *** present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support.

关键词： free vibration conical shell rotating shell ring support auxetic honeycomb

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Orthogonal polynomial expansions for the valuation ofoptions under the stochastic volatility models with stochastic correlation

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Journal of management Science and Engineering 2024年第2期9卷 239-253页

作者： Kevin z.Tong Department of mathematics and Statistics University of Ottawa585 King EdwardOttawaOntarioK1N 6N5Canada

This work provides a new method for pricing options under the generalized stochastic volatility models with Jacobi stochastic *** method is based on the observation that the generalized models belong to the class of polynomial diffusions and therefore the option prices can be efficiently computed via orthogonal polynomial *** take the Heston and Schöbel-zhu models with stochastic correlation as two specific examples and are able to derive the analytical formulas for the option *** also illustrate the accuracy of the proposed method through a number of numerical experiments.

关键词： Orthogonal polynomial expansions Polynomial diffusions Stochastic correlation Jacobi process Stochastic volatility

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Olefin Polymerization Behavior of Titanium(iV) Complexes with Fluorinated and Non-fluorinated Aliphatic Phenoxyimine Ligands

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Chinese Journal of Polymer Science 2024年第1期42卷 52-62,I0007页

作者： Vladislav A.Tuskaev Kasim F.magomedov Svetlana Ch.gagieva Dmitry A.Kurmaev Yulia V.Nelyubina Evgenii K.golubev maria D.Evseeva Viktor g.Vasil'ev galina g.Nikiforova mikhail i.Buzin Vyacheslav S.Bogdanov Boris m.Bulychev Department of Chemistry M.V.Lomonosov Moscow State UniversityMoscow 119992Russian Federation A.N.Nesmeyanov institute of Organoelement Compounds Russian Academy of SciencesMoscow119991Russian Federation Enikolopov institute of Synthetic Polymer materials Russian Academy of SciencesMoscow 117393Russian Federation

A series of Ti(Ⅳ) dichloride and dialkoxide com plexes with phenoxyimine ligands containing fluorinated and nonfluorinated aliphatic imine fragments have been *** molecular structures of complexes 1 and 4 were established by single-crystal X-ray diffraction *** complexes adopt a distorted octahedral coordination structure around the titanium atom and two oxygen atoms are situated in trans position while two nitrogen atoms and two outgoing ligands(Cl or iPrO) are situated in cis *** of activators(mmAO-12 and combinations Et_nAiCl_(3-n)+Bu_(2)mg) and outgoing ligand(Cl or iPrO) nature on the catalytic activity and properties of the resulting polymers was *** Ti complexes,despite the nature of the outgoing ligands(Cl or iPrO) in the presence of Al/mg activators,was found to display a high ethylene polymerization activity in the range 1600-3830 kg_(polymer)·mol_(Ti)^(-1)·h^(-1)·atm^(-1) with a viscosity average molecular weight(m_v) value in the range 1.1×10~6-7.1×10~6 Dalton(Da).The resulting UHmWPE can be processed by a solventless method into high-strength and high-modulus oriented *** rheological characteristics of a polymer melt have been *** absence of a cross-over point did not allow to compare the values of the molecular weight distribution of polymers obtained on fluorinated and non-fluorinated pre-catalysts,however,the estimation of the entanglement density is in good agreement with the mechanical characteristics of oriented film *** activation with methylalumoxane,the activity of the com plexes decreased very significantly;however,a polymer with a molecular weight of about 12 million Da was *** the process of ethylene/octene-1 copolymerization,fluorine-containing precatalysts showed a clear advantage over non-fluorinated analogues both in activity and in comonomer content.

关键词： Fi catalysts Titanium(iV) (Co)polymerization Al/mg co-catalyst Ultra-high molecular weight polyethylene

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Atomistic investigation of Shock-induced Amorphization within micro-shear Bands in Hexagonal Close-Packed Titanium

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Acta metallurgica Sinica(English Letters) 2024年第9期37卷 1590-1600页

作者： z.C.meng K.g.Wang T.Ali D.Li C.g.Bai D.S.Xu S.J.Li A.H.Feng g.J.Cao J.H.Yao Q.B.Fan H.Wang R.Yang institute of metal Research Chinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China interdisciplinary Centre for Additive manufacturing(iCAm) School of Materials and ChemistryUniversity of Shanghai for Science and TechnologyShanghai 200093China School of materials Science and Engineering Tongji UniversityShanghai 201804China Key Laboratory for Light-Weight materials Nanjing Tech UniversityNanjing 210009China National Key Laboratory of Science and Technology on materials Under Shock and impact School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing institute of Technology Chongqing innovation Center Chongqing 401135China

The mechanical response of a single crystal titanium sample against(0001)α surface impact was investigated using molecular dynamics ***,non-uniform plastic deformation was observed in the *** high strain rates,amorphization occurred near the edge of the contact region where severe shear strain induced a large number of stacking faults(SFs)and *** contrast,the central part of the contact region underwent less deformation with significantly fewer ***,instead of amorphization by consuming SFs and dislocations,there was a gradual increase in the density of dislocations and SFs during the process of *** local amorphous regions eventually grew into shear bands.

关键词： Shock compression Amorphization Shear band Titanium molecular dynamics

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Effect of Ta_(2)O_(5)nanoparticles on bioactivity,composition,structure,in vitro and in vivo behavior of PEO coatings on mg-alloy

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Journal of magnesium and Alloys 2024年第6期12卷 2360-2379页

作者： D.V.mashtalyar i.m.imshinetskiy V.V.Kashepa K.V.Nadaraia m.A.Piatkova A.i.Pleshkova K.A.Fomenko A.Yu.Ustinov S.L.Sinebryukhov S.V.gnedenkov institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690950Russia Regional Clinical Dermatovenerological Dispensary Vladivostok690033Russia

The present study investigates the physical and chemical characteristics,behavior in vitro and in vivo,and biocompatibility of coatings containing Ta_(2)O_(5),which are obtained by plasma electrolytic oxidation(PEO)on mA8 magnesium *** obtained coatings demonstrate in vivo biocompatibility and in vitro *** to the base PEO coating,the layers containing Ta_(2)O_(5)facilitate the development of apatite in simulated body fluid,suggesting that the inclusion of nanoparticles improves bioactivity of the *** was found that incorporation of Ta_(2)O_(5)nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in *** on in vivo studies,these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen *** results obtained in the present study concluded biocompatibility,tissue integration of the PEO coatings containing Ta_(2)O_(5)nanoparticles making them a promising protective layer for biodegradable magnesium implants.

关键词： Plasma electrolytic oxidation Bioactive coatings Tantalum pentoxide Simulated body fluid(SBF) Apatite formation Histology

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Antibacterial HA-coatings on bioresorbable mg alloy

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Journal of magnesium and Alloys 2024年第5期12卷 1965-1985页

作者： K.V.Nadaraia D.V.mashtalyar m.A.Piatkova A.i.Pleshkova i.m.imshinetskiy m.S.gerasimenko E.A.Belov V.V.Kumeiko D.N.Kozyrev K.A.Fomenko V.V.mostovaya B.R.Torpanov A.R.Biktimirov i.S.Osmushko S.L.Sinebryukhov S.V.gnedenkov institute of Chemistry FEB RAS 159 Pr.100-letiya VladivostokaVladivostok 690022Russia Far Eastern Federal University 10 Ajax BayRussky IslandVladivostok 690922Russia A.V.zhirmunsky National Scientific Center of marine Biology FEB RAS 17 St.PalchevskogoVladivostok 690041Russia Regional Clinical Dermatovenerological Dispensary 18 V St.GamarnikaVladivostok 690033Russia NmiC“Treatment and Rehabilitation Center” 3 Ivankovskoe highwayMoscow 125367Russia

in this study,a calcium-phosphate coating was formed on a mg-mn-Ce alloy by the plasma electrolytic oxidation(PEO).The antibiotic vancomycin,widely used in the treatment of infections caused by Staphylococcus aureus(***),was impregnated into the *** with vancomycin showed high bactericidal activity against *** mechanical and electrochemical properties of the formed coatings were studied,as well as in vitro cytotoxicity tests and in vivo tests on mature male rats were *** to SEm,EDS,XRD and XPS data,coatings had a developed morphology and contained hydroxyapatite,which indicates high *** analysis of roughness of coatings without and with vancomycin did not reveal any differences,confirming the high roughness of the *** electrochemical tests,an increase in corrosion resistance by more than two times after the application of PEO coatings was *** to the results of an in vivo study,after 28 days of the implantation of samples with calcium phosphate PEO coating and vancomycin,no signs of inflammation were observed,while an inflammatory reaction developed in the area of implantation of bare alloy,followed by *** release tests from the coatings show a sharp decrease in the concentration of the released antibiotic on day 7 and then a gradual decrease until day *** the experiment,no significant deviations in the condition and behavior of the animals were observed;clinical tests did not reveal a systemic toxic reaction.

关键词： Bioactive coatings Biocompatibility mg alloy Plasma electrolytic oxidation Hydroxyapatite Vancomycin

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Probing the Bardeen-Kiselev black hole with the cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds

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Communications in Theoretical Physics 2024年第6期76卷 102-119页

作者： S R Wu B Q Wang z W Long College of Physics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

in this work,we investigate a static and spherically symmetric Bardeen-Kiselev black hole(BH)with the cosmological constant,which is a solution of the Einstein-non-linear maxwell field *** compute the quasinormal frequencies for the Bardeen-Kiselev BH with the cosmological constant due to electromagnetic and gravitational *** varying the BH parameters,we discuss the behavior of both real and imaginary parts of the BH quasinormal frequencies and compare these frequencies with the Reissner-Nordström-de Sitter BH surrounded by quintessence(RN-dSQ).interestingly,it is shown that the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ under electromagnetic perturbations are different when the charge parameter q,the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ are different only when the charge parameter q is ***,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the Bardeen-Kiselev BH with the cosmological constant damps faster and oscillates slowly;for the gravitational perturbations,the quasinormal mode decays slowly and oscillates *** also study the reflection and transmission coefficients along with the absorption cross section in the Bardeen-Kiselev BH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev quintessence.

关键词： quasinormal modes greybody factors Bardeen-Kiselev black hole with cosmological constant

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Estimation of Equivalent model of Photovoltaic Array Using Unscented Kalman Filters

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Journal of modern Power Systems and Clean Energy 2024年第3期12卷 819-827页

作者： m.A.gonzález-Cagigal JoséA.Rosendo-macías A.gómez-Expósito the Department of Electrical Engineering University of SevilleSpainand A.Gómez-Expósito is also with ENGREEN Laboratory of Engineering for Energy and Environmental SustainabilitySevilleSpain

This paper proposes the use of the unscented Kalman filter to estimate the equivalent model of a photovoltaic(PV)array,using external measurements of current and voltage at the inverter *** estimated model is of interest to predict the power output of PV plants,in both planning and operation scenarios,and thus improves the efficient operation of power systems with high penetration of renewable *** proposed technique has been assessed in several simulated scenarios under different operating *** results show that accurate estimates are provided for the model parameters,even in the presence of measurement noise and abrupt variations under the external conditions.

关键词： Equivalent model parameter estimation photovoltaic energy unscented Kalman filter

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