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A numerical study on the influence of grain boundary oxides on dwell fatigue crack growth of a nickel-based superalloy

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journal of Materials Science & Technology 2022年第9期104卷 224-235页

作者： C.Z.Fang H.C.Basoalto M.j.Anderson H.Y.Li S.j.Williams P.Bowen Department of Materials Science and Engineering University of SheffieldMappin StSheffield S13JDUK School of Metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK Institute of Structural Materials Swansea UniversitySwansea SA18ENUK

A theoretical treatment on the oxide-controlled dwell fatigue crack growth of aγ'strengthened nickelbased superalloys is *** particular,this study investigates the influence of an externally applied load and variations in theγ'dispersion on the grain boundary oxide growth kinetics.A dislocation-based viscoplastic constitutive description for high temperature deformation is used to simulate the stress state evolution in the vicinity of a crack at elevated *** viscoplastic model explicitly accounts for multimodalγ'particle size distributions.A multicomponent mass transport formulation is used to simulate the formation/evolution of an oxide wedge ahead of the crack tip,where stress-assisted vacancy diffusion is assumed to *** resulting set of constitutive and mass transport equations have been implemented within a finite element *** of predicted compositional fields across the matrix/oxide interface are compared with experiments and shown to be in good *** indicate that the presence of a fineγ'size distribution has a strong influence on the predicted ow stress of the material and consequently on the relaxation in the vicinity of the crack-tip/oxide *** is shown that a unimodal dispersion leads to reduced oxide growth rates(parabolic behavior)when compared to a bimodal *** conditions for oxide formation are investigated and is associated with the prediction of compressive stresses within the oxide layer just ahead of the crack tip,which become progressively negative as the oxide wedge ***,mechanical equilibrium requirements induce tensile stresses at the tip of the oxide wedge,where failure of the oxide is *** time taken to reach this critical stress for oxide failure has been calculated,from which dwell crack growth rates are computationally *** predicted rates are shown to be in good agreement with available experimental data.

关键词： Nickel based superalloy Dwell crack growth Gamma prime Creep Oxidation Dislocation-based modeling Multicomponent diffusion Finite element method

INTRASPINAL CONNECTIONS OF DORSAL COLUMN POSTSYNAPTIC NEURONS IN THE CAT——A PHYSIOLOGICAL ANALYSIS

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Science China Chemistry 1985年第9期28卷 972-978页

作者：吕国蔚,GARY j.BENNETT,NOZOMU NISHIkAWA,MARVIN j.HOFFERT,RONALD DUBNER Department of Neurophysiology Beijing Second Medical College China Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Department of Anesthesiology Shiga University of Medical Seience Shiga japan Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA Department of Neurology Univeraity of Wisenonsin Medieal School Madison Wisconsin 53792 U.S.A Neurobiology and Anesthesiology Branch National Institute of Dental Research National Institutes of Health USA

Dorsal column postsynaptic (DCPS) neurons in the dorsal horn of the spinal cord have been identified by antidromic stimulation and intracellularly recorded in anesthetized cats. In about one-half of the cells, the antidromic stimulus evokes only an antidromic potential. This potential sometimes has an atypical shape due to penetration-induced depolarization. Atypieal potentials arc converted into typical antidromic spike potentials after intracellular injection of hyperpolarizing current. In the other one-half, the antidromic potentials are followed by postsynaptic activity. Intracellular analysis indicates that this postsynaptic activity is generated largely by activation of the intraspinal collaterals of A-beta primary afferents that are ascending the dorsal columns. Part of this postsynaptic activity has been produced monosynaptically. Polysynaptic responses are also evident; these are thought to be initiated by A-beta axons, desending axons from neurons in the dorsal column nuclei, or the local coll

关键词： A PHYSIOLOGICAL ANALYSIS

Taxonomic species recognition should be consistent

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National Science Review 2022年第12期9卷 17-18页

作者： Stephen j.O'Brien Shu-jin Luo Guy Harvey Oceanographic Center Halmos College of Arts and Sciences Nova Southeastern University The State key Laboratory of Protein and Plant Gene Research School of Life Sciences and Peking-Tsinghua Center for Life Sciences Academy for Advanced Interdisciplinary Studies Peking University

Criteria for species naming have been contentious since the time of Carl *** no clear’right or wrong’convention for species naming,biologists strive to simply convince their *** NSR compendium offers detailed guidance [1-6] that adds quantitative genomic inference to the *** taxonomic assemblages (***,fish,fungi,insects,terrestrial and marine invertebrates,plants,bacteria) are sufficiently distinctive that any generalization is fraught with natural exceptions.

关键词： PHYLOGEOGRAPHY

Evaluation of Microstructure and Magnetic Properties in Non-oriented Electrical Steel Strained by Tension

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journal of Iron and Steel Research International 2016年第2期23卷 166-170页

作者： j.SALINAS B. A.SALINAS R. Engineering Metallurgical Research Center and Advanced Studies of National Polytechnic Institute

The effects of deformation on the microstructure and magnetic properties of non oriented electrical steels were investigated. Box annealed electrical steel sheets were deformed by tension at four different strains： 3%, 8%, 12 % and 25 % The internal grain misorientation caused by tensile deformation was measured by electron backscat- tering diffraction （EBSD） with grain orientation spread （GOS） as an indicator of the lattice distortion. The experi- mental results showed that the average GOS value increases with the strain. The microstructure and crystallographic texture of deformed samples did not show a significant change in samples strained below 25 %. However, the mag- netic properties were strongly affected： coercivity was directly proportional to the square root of the GOS value and energy losses increased as the strain level was increased.

关键词： non-oriented electrical steel tensile deformation internal misorientation magnetic property EBSD

Terbium-doped heavy metal glasses for green luminescence

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journal of Rare Earths 2011年第12期29卷 1198-1200页

作者： L.Zur j.Pisarska W.A.Pisarski Institute of Chemistry University of Silesia

Compositional-dependent heavy metal lead borate glasses doped with Tb^3＋ ions were investigated. Green luminescence related to main ^5D4→^7F5 （543 nm） transition was registered under excitation of ^5D3 state of Tb^3＋ ions. Based on excitation and luminescence measurements, several spectroscopic parameters for Tb3＋ ions were examined as a function of heavy metal PbO content. Luminescence decay analysis indicated that the ^5D4 luminescence lifetime of Tb^3＋ reduced from 2.83 to 1.42 ms, when PbO：B203 ratio was changed from 1：1 to 4：1.

关键词： glasses Tb^3+ ions excitation luminescence rare earths

Portable System for CWA Detection Using Micro Array Gas Sensor

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稀有金属材料与工程 2006年第A3期35卷 124-128页

作者： j.H.kwak Y.T.Lim G.H.kim N.j.Choi H.D.Park G.H.Rue j.S.Huh j.C.kim D.D.Lee School of Electrical Engineering and Computer Science Kyungpook National UniversityDaegu 1370Korea Electronics and Telecommunications Research Institute Future Technology Research Division New Functional Information Devices TeamGajeongYuseong-GuDaejeon 161 Korea korea Electronics Technology Institute Yatap-DongBundang-GuSeongnam-SiGyeonggi-Do #68Korea Department of Materials Science and Metallurgy Kyungpook National UniversityDaegu 1370Korea Department of Chemical Engineering Kyungpook National UniversityDaegu 1370Korea

Biochemistry weapon is raising new tools of war and *** research is an experiment about portable system for CWAs (chemical warfare agents) detection using micro array gas *** were divided into four types such as blood, nerve,vesicant,and choking *** detect various CWAs,semiconductor thick film sensor array based on tin oxide was fabricated and their gas responses were *** temperature was range of 250℃to 350℃and gas concentration was range of 0.1μg/g to 10μg/*** array was measured as operating temperatures,concentrations for four simulant agents of *** parameters from results were carried out classification among CWAs through the principal component analysis (PCA).Also,classification of gases is studied using adaptive resonance theory (ART) that is one of neural network *** displayed using PDA system.

关键词： SnO2 chemical warfare agents(CWAs) portable system ART array PCA

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基础护理

基础护理

Method and its application of the momentum model for debris flow risk zoning

作者： k.C.·索伦森(k.C. Sorensen) j.·拉克曼(j. Luckmann)

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Chinese Science Bulletin 2003年第6期48卷 594-598页

作者： WEIFangqiang j.L.Lopez 等 InstituteofMountainHzardsandEnvironment ChineseAcademyofSciencesChengdu610041China InstiuteofFluidMechanics CentralUniversityofVenczuelaCaracasVenezuela

In order to ascertain the distribution of flow depth and velocity of debris flow, the combination of nu-merical modeling and the GIS technology has been used to simulate the movement process of debris flow out of the out-let. The main model of momentum classification of risk zon-ing of debris flow is Z=khv. Based on the distribution of the velocity and depth of debris flow, the distribution of mo-mentum can be ascertained. Thereby the classification of risk zoning of debris flow can be worked out. A case study of Chacaito Valley in Caracas, Venezuela, is presented to illus-trate the application of the method.

关键词：泥石流风险区划动量模型数值模拟应用 GIS

Methanol oxidation in acidic and alkaline electrolytes using PtRuIn/C electrocatalysts prepared by borohydride reduction process

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燃料化学学报 2018年第12期46卷 1462-1471页

作者： Santos M.C.L. Nandenha j. Ayoub j.M.S. Assumpao M.H.M.T. Neto A.O. Instituto de Pesquisas Energéticas e Nucleares IPEN/CNEN-SPAv.Prof.Lineu Prestes2242 Cidade UniversitáriaCEP 05508-000Sao PauloSPBrazil Universidade Federal de Sao Carlos UFSCar Campus Lagoa do Sino Rodovia Lauri Simoes de Barros Km 12 CEP 18290-000-Buri-Sao Paulo SP Brazil

PtRuIn/C electrocatalysts( 20% metal loading by weight) were prepared by sodium borohydride reduction process using H_2PtCl6·6H_2O,RuCl_3·xH_2O and InCl_3·xH_2O as metal sources,borohydride as reducing agent and Carbon Vulcan XC72 as support. The synthetized PtRuIn/C electrocatalysts were characterized by X-ray diffraction( XRD),energy dispersive analysis( EDX),transmission electron microscopy( TEM),cyclic voltammetry( CV),chronoamperommetry( CA) and polarization curves in alkaline and acidic electrolytes( single cell experiments). The XRD patterns showPtpeaks are attributed to the face-centered cubic( fcc) structure,and a shift of Pt( fcc) peaks indicates that Ru or In is incorporated into Ptlattice. TEMmicrographs showmetal nanoparticles with an average nanoparticle size between 2.7 and 3.5 nm. Methanol oxidation in acidic and alkaline electrolytes was investigated at room temperature,by CV and CA. PtRu/C( 50 ∶ 50) shows the highest activity among all electrocatalysts in study considering methanol oxidation for acidic and alkaline electrolyte. Polarization curves at 80 ℃ showPtRuIn/C( 50 ∶ 25 ∶ 25)with superior performance for methanol oxidation,when compared to Pt/C,PtIn/C and PtRu/C for both electrolytes. The best performance obtained by PtRuIn/C( 50 ∶ 25 ∶ 25) in real conditions could be associated with the increased kinetics reaction and/or with the occurrence simultaneously of the bifunctional mechanism and electronic effect resulting from the presence of Ptalloy.

关键词： borohydride reduction process PtRuIn/C electrocatalysts methanol oxidation acidic and alkaline electrolytes polarization curves