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An index for deformation controllability of small-volume materials

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Science China(Technological Sciences) 2014年第4期57卷 663-670页

作者： WANG Zhangjie SHAN ZhiWei LI ju SUN jun MA evan Center for Advancing Materials Performance from the Nanoscale CAMP-Nano) & Hysitron Applied Research Center in China (HARCC) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Department of Nuclear Science and Engineering and Department of Materials Science and Engineering Massachusetts Institute of Technology Department of Materials Science and Engineering Johns Hopkins University

Mechanical tests on small-volume materials show that in addition to the usual attributes of strength and ductility,the controllability of deformation would be crucial for the purpose of precise plastic *** our present work,a"mechanical controllability index"(MCI)has been proposed to assess the controllability of mechanical deformation *** index allows quantitative evaluation of the relative fraction of the controllable plastic strain out of the total ***=0 means completely uncontrollable plastic deformation,MCI=∞means perfectly controllable plastic *** application of the index is demonstrated here by comparing two example cases:0.273 to 0.429 for single crystal Al nanopillars that exhibit obvious strain bursts,versus 3.17 to 4.2 for polycrystalline Al nanopillars of similar size for which the stress-strain curve is smoother.

关键词：材料变形可控性小批量机械变形 MCI 力学测试塑料成形塑性应变

In-situ surface transformation of magnesium to protect against oxidation at elevated temperatures

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journal of Materials Science & Technology 2020年第9期44卷 48-53页

作者： Yuecun Wang Meng Li Yueqing Yang Xin’ai Zhao evan Ma Zhiwei Shan Center for Advancing Materials Performance from the Nanoscale(CAMP-Nano)&Hysitron Applied Research Center in China(HARCC) State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an710049China Department of Materials Science and Engineering Johns Hopkins UniversityBaltimore21218MDUSA

The native oxide thin scale on magnesium(Mg)surface appears continuous and crack-free,but cannot protect the Mg matrix from further oxidation,especially at elevated *** thermal oxidation process is witnessed in its entirety using a home-made in-situ heating device inside an environmental electron transmission *** proposed,and verified with real-time experimental evidence,that transforming the native oxide scale into a thin continuous surface layer with high vacancy formation energy(low vacancy concentration),for example MgCO3,can effectively protect Mg from high-temperature oxidation and raise the threshold oxidation temperature by at least two hundred degrees.

关键词： Magnesium Thermal oxidation In-situ E-TEM Carbonation Oxidation inhibition

Adoption of technologies that enhance soil carbon sequestration in East Africa. What influence farmers' decision?

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International Soil and Water Conservation Research 2020年第1期8卷 90-101页

作者： Stanley Karanja Ng'ang'a Dorcas Anyango jalang'o evan Hartunian Girvetz International Centre for Tropical Agriculture(CIAT) National Agricultural Research Laboratories-KawandaP.O.Box 6247KampalaUganda International Centre for Tropical Agriculture(CIAT) P.O.Box 823-00621NairobiKenya

The last two decades have seen a rise of interest in the adoption and diffusion of agricultural technologies aimed at improving the sustainability of agricultural lands among smallholder farmers in developing *** papers set out to understand factors that influence the adoption of technologies that enhance soil carbon sequestration among smallholder farmers,using secondary data recorded in the World Overview of Conservation Approaches and Technologies(WOCAT)database from 45 to 50 smallholders'farmers in selected places in Kenya and Ethiopia respectively.A Probit model was used to analyse whether socio-economic,institutional,off-farm income,technical know-how,farmers'percep-tions,and land use characteristics influences the adoption of technologies that enhance soil carbon *** results show that smallholder farmers that positively perceived net benefits of the soil carbon enhancing technologies were more likely to adopt such technologies that enhance soil carbon sequestration in both *** to off-farm income and land ownership with title deeds were also found to be positively associated with ***-farm income positively influences adoption among farmer with a moderate income(100-500US$per year)but not the rich(>500US$)*** to high level of skills and technical know-how required for implementing and maintaining a technology on the farm had a negative influence on *** shows that interventions,aimed at addressing specific factors such as inadequate skills and knowledge,change in perception among farmers,and off-farm income are likely to have the greatest impact in decisions relating to the adoption of the soil carbon enhancing practices among farmers in East Africa.

关键词： Factors Influencing The adoption Soil carbon Sequestration East Africa

Application of the neuromuscular fatigue threshold treadmill test to muscles of the quadriceps and hamstrings

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journal of Sport and Health Science 2020年第6期9卷 628-633页

作者： Clayton L.Camic Attila j.Kovacs Trisha A.VanDusseldorp Ethan C.Hill evan A.Enquist Human Performance Laboratory Exercise and Sport ScienceUniversity of Wisconsin-La CrosseLa CrosseWisconsin 54601USA Department of Exercise Science and Sport Management Kennesaw State UniversityKennesawGeorgia 30144USA Department of Nutrition and Health Sciences University of Nebraska-LincolnLincolnNebraska 68583USA Department of Kinesiology University of AlabamaTuscaloosaAlabama 35487USA

Purpose:The purposes of the present study were:(1)to determine whether the physical working capacity at the fatigue threshold(PWCFT)model that has been used for estimating the onset of neuromuscular fatigue in the vastus lateralis(VL)during incremental treadmill running could also be applied to the vastus medialis(VM),biceps femoris(BF),and semitendinosus(ST)muscles;and(2)if applicable,to compare the running velocities associated with the PWCFT among these ***:Eleven subjects(age 21.7±1.8 years)performed an incremental treadmill test to exhaustion with electromyographic signals recorded from the VL,VM,BF,and ***:The results indicated there were no significant(p>0.05)mean differences in the running velocities associated with the PWCFT for the VL(14.4±2.0 km/h),VM(14.3±1.9 km/h),BF(13.8±1.8 km/h),and ST(14.7±2.3 km/h).In addition,there were significant inter-correlations(r=0.68-0.88)among running velocities associated with the PWCFT of each *** results also indicated that 9 of the 11 subjects exhibited identical PWCFT values for at least 3 of the 4 muscles,but there were no uniform patterns for any intra-individual ***:The findings of the present study suggested that the PWCFT test is a viable method to identify neuromuscular fatigue in the quadriceps and hamstrings during incremental treadmill exercise and results in consistent PWCFT values among these muscles.

关键词： EMG amplitude Muscle activation PWCFT

Weave geometry generation avoiding interferences for mesoscale RVEs

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journal of Materials Science & Technology 2019年第12期35卷 2869-2882页

作者： Daniel Höwer Shengkai Yu Trenton M.Ricks Brett A.Bednarcyk evan j.Pineda Bertram Stier Stefanie Reese jaan-Willem Simon Institute of Applied Mechanics RWTH Aachen University52074 AachenGermany NASA Glenn Research Center ClevelandOH 44135USA Collier Research and Development Corporation Newport NewsVA 23606USA

An algorithm which allows the generation of representative volume elements(RVEs) for complex woven and warp-interlaced fiber-reinforced composite topologies while avoiding unphysical tow intersections is presented. This is achieved by extending an existing RVE generation strategy in two significant ways:(1) the local cross section shape of the tow is adjusted depending on the local tow curvature in a way that preserves the cross sectional area of the tow, and(2) the elementary crimp interval is separated into a planar and a transition region. The modifications facilitate the generation of a wide range of elaborate textile topologies without tow intersections, which are present without the proposed modifications unless complex tow to tow contact models are introduced. The mechanical properties of plain weaves were predicted based on the topology generated with the proposed algorithm as well as based on RVEs which were constructed based on actual micrographs, i.e. a "digital twin" of the actual microstructure. A comparison of the predicted mechanical properties based on finite element and Multiscale Generalized Method of Cells techniques shows close agreement. However, some differences exist with respect to experimentally determined material parameters due to the finite dimensions of the specimens. Lastly,mechanical properties of multilayered weaves are predicted with the finite element method. The considered material systems are carbon fiber in epoxy matrix as well as C/C-SiC. However, the procedure is applicable to a wide range of material systems.

关键词： RVE generation Multiscale analysis Composites

The effect of surface electronic structures of Au/TiO_2 on sonophotochemical reactions

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Chinese Chemical Letters 2018年第6期29卷 783-786页

作者： Kun Qian evan Wenbo Zhao Shuai He Wei David Wei Department of Chemistry and Center for Catalysis University of Florida Department of Chemical Physics University of Science and Technology of China

Sonophotocatalysis combines ultrasonic and light irradiations to drastically boost the chemical reaction rate and has attracted many interests for its potential applications in the environmental remediation and protection. However, it still remains unclear whether the light irradiation could couple with the ultrasound to prompt the sonophotocatalytic process. Here, we selectively excited the TiO2 and Au to manipulate the electronic structures of Au/TiO2 and studied their influence in sonophotocatalytic water（H2 O） reduction. Surprisingly, no significant increase of the hydrogen（H2） production rate was observed under either the UV light irradiation or the visible light irradiation, suggesting that the change in electronic structures of Au/TiO2 does not prompt the generation of free radicals under sonication and the reaction is dominated by the recovery of active sites through ultrasound. Our findings established an indepth understanding of the origin of the enhanced catalytic activity in sonophotocatalysis.

关键词： Sonophotocatalysis Localized surface plasmon resonance Electronic structure Water reduction Au/TiO2

Apolipoprotein E, amyloid-beta, and neuroinflammation in Alzheimer's disease

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Neuroscience Bulletin 2014年第2期30卷 317-330页

作者： evan Dorey Nina Chang Qing Yan Liu Ze Yang Wandong Zhang Faculty of Medicine University of Ottawa Human Health Therapeutics National Research Council of Canada Institute of Geriatrics/Beijing Hospital Ministry of Health of China

Alzheimer＇s disease （AD） is characterized by the accumulation and deposition of amyloid-beta （Aβ） peptides in the brain. Neuroinflammation occurs in the AD brain and plays a critical role in the neurodegenerative pathology. Particularly, Aβ evokes an inflammatory response that leads to synaptic dysfunction, neuronal death, and neurodegeneration. Apolipoprotein E （ApoE） proteins are involved in cholesterol transport, Aβ binding and clearance, and synaptic functions in the brain. The ApoE4 isoform is a key risk factor for AD, while the ApoE2 isoform has a neuroprotective effect. However, studies have reached different conclusions about the roles of the isoforms; some show that both ApoE3 and ApoE4 have anti-inflammatory effects, while others show that ApoE4 causes a predisposition to inflammation or promotes an inflammatory response following lipopolysaccharide treatment. These discrepancies may result from the differences in models, cell types, experimental conditions, and inflammatory stimuli used. Further, little was known about the role of ApoE isoforms in the Aβ-induced inflammatory response and in the neuroinflammation of AD. Our recent work showed that ApoE isoforms differentially regulate and modify the Aβ-induced inflammatory response in neural cells, with ApoE2 suppressing and ApoE4 promoting the response. In this article, we review the roles, mechanisms, and interrelations among Aβ, ApoE, and neuroinflammation in AD.

关键词： ApoE Alzheimer's disease Aβ neuroinflammation

Intracellular compartmentation of cAMP promotes neuroprotection and regeneration of CNS neurons

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Neural Regeneration Research 2017年第2期12卷 201-202页

作者： evan G.Cameron Michael S.Kapiloff Byers Eye Institute Stanford University Departments of Pediatrics and Medicine Leonard M.Miller School of MedicineUniversity of Miami

In the central nervous system（CNS）,cyclic adenosine monophosphate（cAMP）plays a critical role in numerous,often concurrent,neuronal functions including survival,growth,differentiation and synaptogenesis.

关键词： AMP PDEs CNS

Striving for decreased post-transplant hepatocellular carcinoma recurrence without excluding potentially curable patients: the utility of tumor biology

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Hepatobiliary Surgery and Nutrition 2019年第5期8卷 541-542页

作者： Russell evan Rosenblatt Karim jarir Halazun Weill Cornell Medicine New YorkUSA

The Milan criteria truly transformed the field oftransplantation for hepatocellular carcinoma bydemonstrating that excellent recurrence-free survival(RFS)can be achieved in small tumors(1).Over the years,theallowable tumor size and number prior to transplantationwas challenged by several groups and thus continued toexpand,but the use of simple morpho-metrics alwayslimited the ability to predict tumor recurrence,as markersof tumor biology were not routinely *** recently,multiple studies have combined biomarkers with tumor sizeand number to create increasingly accurate scoring systemsto better predict RFS.

关键词： hepatocellular routine continued