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Synthesis of Polynorbornene-Poly(ethylene-co-propylene)Diblock Copolymer

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Chinese Chemical Letters 1998年第5期9卷 447-450页

作者： Wu, q Wen, q Lu, ZJ Zhongshan Univ Inst Polymer Sci Canton 510275 Peoples R China

Transformation of living ring-opening metathesis polymerization into coordination polymerization by converting the titanacyclobutane group attached to a polynorbornene chain into titanocene alkoxide has been used for the synthesis of polynorbornene-poly(ethylene-co-propylene) block copolymer. Preliminary characterizations of the copolymerization products by solvent extraction and C-13 NMR spectrum are reported.

关键词： ring-opening metathesis polymerization coordination polymerization diblock copolymer norbornene ethylene propylene

Overexpression of Arabidopsis Sorting Nexin AtSNX2b Inhibits Endocytic Trafficking to the Vacuole

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Molecular Plant 2008年第6期1卷 961-976页

作者： Nguyen q. Phan Department of Genetics Development and Cell Biology Iowa State University Ames IA 50011 USA Interdepartmental Genetics Program Iowa State University Ames IA 50011 USA Plant Sciences Institute Iowa State University Ames IA 50011 USA

Sorting nexins are conserved proteins that function in vesicular trafficking and contain a characteristic phox homology （PX） domain. Here, we characterize the ubiquitously expressed Arabidopsis thaliana sorting nexin AtSNX2b. Sub-cellular fractionation studies indicate that AtSNX2b is peripherally associated with membranes. The AtSNX2b PX domain binds to phosphatidylinositol 3-phosphate in vitro and this association is required for the localization of GFPAtSNX2b to punctate structures in vivo, identified as the trans-Golgi network, prevacuolar compartment and endosomes. Overexpression of GFP-tagged AtSNX2b produces enlarged GFP-labeled compartments that can also be labeled by the endocytic tracer FM4-64. Endocytic trafficking of FM4-64 to the vacuole is arrested in these GFP-AtSNX2b compartments, and similar FM4-64-accumulating compartments are seen upon overexpression of untagged AtSNX2b. This suggests that exit of membrane components from these enlarged or aggregated endosomes is inhibited. Vacuolar proteins containing an N-terminal propeptide, but not those with a C-terminal propeptide, are also present in these enlarged compartments. We hypothesize that AtSNX2b is involved in vesicular trafficking from endosomes to the vacuole.

关键词： phox homology Overexpression Vacuole

A simple criterion for finite time stability with application to impacted buckling of elastic columns

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Applied Mathematics and Mechanics(English Edition) 2018年第3期39卷 305-316页

作者： C.q.RU Department of Mechanical Engineering University of Alberta

The existing theories of finite-time stability depend on a prescribed bound on initial disturbances and a prescribed threshold for allowable responses. It remains a challenge to identify the critical value of loading parameter for finite time instability observed in experiments without the need of specifying any prescribed threshold for al- lowable responses. Based on an energy balance analysis of a simple dynamic system, this paper proposes a general criterion for finite time stability which indicates that finite time stability of a linear dynamic system with constant coefficients during a given time interval [0, tf] is guaranteed provided the product of its maximum growth rate （determined by the maximum eigen-root pl 〉0） and the duration tf does not exceed 2, i.e., pltf 〈2. The proposed criterion （pltf=2） is applied to several problems of impacted buckling of elastic columns：（i） an elastic column impacted by a striking mass, （ii） longitudinal impact of an elastic column on a rigid wall, and （iii） an elastic column compressed at a constant speed （＂Hoff problem＂）, in which the time-varying axial force is replaced approximately by its average value over the time duration. Comparison of critical parameters predicted by the proposed criterion with available experimental and simulation data shows that the proposed criterion is in robust reasonable agreement with the known data, which suggests that the proposed simple criterion （pltf---2） can be used to estimate critical parameters for finite time stability of dynamic systems governed by linear equations with constant coefficients.

关键词： finite time stability, buckling impact, elastic column, Hoff problem, dy-namic buckling, stability criterion

青藏高原及其周边二叠纪综合地层、生物群以及古地理和古气候演化

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中国科学：地球科学 2024年第4期54卷 1125-1170页

作者：沈树忠张以春袁东勋徐海鹏琚琦张华郑全锋罗茂侯章帅南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室关键地球物质循环前沿科学中心南京210023 中国科学院南京地质古生物研究所现代古生物学和地层学国家重点实验室南京210008 中国科学院大学南京学院南京210049 中国矿业大学资源与地球科学学院徐州221116

二叠纪是青藏高原各块体演化的关键时段,发生了一系列重大地质和生物事件,当时横跨南北半球统一的泛大陆演化到了鼎盛阶段,阻断了全球东西向的赤道暖流的同时,在泛大陆的东侧形成了一个半封闭的、具有重要历史意义的特提斯洋暖池,是古-... 详细信息

二叠纪是青藏高原各块体演化的关键时段,发生了一系列重大地质和生物事件,当时横跨南北半球统一的泛大陆演化到了鼎盛阶段,阻断了全球东西向的赤道暖流的同时,在泛大陆的东侧形成了一个半封闭的、具有重要历史意义的特提斯洋暖池,是古-中生代之交生物与环境演变的引擎.青藏高原二叠纪地层分布广泛、化石丰富,从南到北由于跨越不同的纬度带体现出不同的特点.雅鲁藏布江以南的喜马拉雅特提斯带当时位于冈瓦纳大陆印度板块北缘,整个二叠纪沉积含有典型的冈瓦纳冷水型生物群;雅鲁藏布江缝合带内的灰岩外来体时代集中在瓜德鲁普世(Guadalupian,中二叠世)中、晚期至早三叠世,古生物地理与喜马拉雅特提斯带有显著差异,最有可能为新特提斯洋中的海山型沉积.基墨里(Cimmerian)微地块群在乌拉尔世(Cisuralian,早二叠世)早期阿瑟尔期-萨克马尔期(Asselian-Sakmarian)全部位于冈瓦纳大陆北缘,均发育冰海相沉积及冈瓦纳型冷水生物群.乌拉尔世中期(约290~280Ma)基墨里微地块群由于印度板块北缘Panjal Traps等大火成岩省岩浆活动与冈瓦纳大陆裂解,并以不同的速度向北漂移.可以分为两个条带,由南羌塘、保山和Sibuma地块组成的北基墨里微地块群漂移速度较快,在亚丁斯克期(Artinskian)就已经出现大量碳酸盐岩沉积和暖水生物群,因此,它们最先从冈瓦纳大陆裂解并进入低纬度暖水区域;而由拉萨、腾冲和Irrawaddy地块组成的南基墨里微地块群,漂移速度相对较慢,在空谷(Kungurian)晚期才开始出现大规模碳酸盐岩沉积,并延续至乐平世(Lopingian,晚二叠世),瓜德鲁普世和乐平世地层中含暖水生物为主的动物群,因此,这些地块至少在空谷晚期已经从冈瓦纳大陆北缘分离,裂解时间稍晚于北基墨里微地块群;这种沉积和古生物地理的时空演变差异性表明乌拉尔世的裂解事件造成了中特提斯洋和新特提斯洋的开启和形成.更北的北羌塘地块由于整个二叠纪地层中均含有典型的暖水生物群,与华南地区、思茅地块和印支地块等可以比较,属于古特提斯洋北部的块体.因此,二叠纪中、晚期特提斯域形成了古、中、新特提斯多岛洋共存的局面,是当时构造活动最活跃的地区和全球生物多样性的中心.此外,青藏高原多个块体在二叠纪位于南半球中高纬度地区,完整记录了晚古生代大冰期、亚丁斯克期全球变暖和二叠纪末快速变暖等重大古气候事件,对于阐明板块运动和全球气候演变对生物群时空分布的影响具有举足轻重的作用.

关键词：二叠纪特提斯洋青藏高原生物群古地理

Reducing the anisotropy of a Brazilian disc generated in a bonded-particle model

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Acta Mechanica Sinica 2018年第4期34卷 716-727页

作者： q.Zhang X.P.Zhang P.q.Ji The Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province School of Civil EngineeringWuhan University

The Brazilian test is a widely used method for determining the tensile strength of rocks and for calibrating parameters in bondedparticle models（BPMs）. In previous studies, the Brazilian disc has typically been trimmed from a compacted rectangular specimen. The present study shows that different tensile strength values are obtained depending on the compressive loading direction. Several measures are proposed to reduce the anisotropy of the disc. The results reveal that the anisotropy of the disc is significantly influenced by the compactibility of the specimen from which it is trimmed. A new method is proposed in which the Brazilian disc is directly generated with a particle boundary, effectively reducing the anisotropy. The stiffness（particle and bond） and strength（bond） of the boundary are set at less than and greater than those of the disc assembly, respectively,which significantly decreases the stress concentration at the boundary contacts and prevents breakage of the boundary particle bonds. This leads to a significant reduction in the anisotropy of the disc and the discreteness of the tensile strength. This method is more suitable for carrying out a realistic Brazilian test for homogeneous rock-like material in the BPM.

关键词： Bonded-particle model Brazilian disc Anisotropy Compactibility Particle boundary

Reliability of quasi integrable and non-resonant Hamiltonian systems under fractional Gaussian noise excitation

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Acta Mechanica Sinica 2020年第4期36卷 902-909页

作者： q.F.Lu W.q.Zhu M.L.Deng Department of Mechanics State-Key Laboratory of Fluid Power and Mechatronic SystemsZhejiang UniversityHangzhou 310027China

The reliability of quasi integrable and non-resonant Hamiltonian system under fractional Gaussian noise(fGn)excitation is *** rather flat fGn power spectral density(PSD)in most part of frequency band,the fGn is innovatively regarded as a wide-band ***,the stochastic averaging method for quasi integrable Hamiltonian systems under wide-band noise excitation is applied to reduce 2n-dimensional original system into n-dimensional averaged ltd stochastic differential equations(SDEs).Reliability function and mean first passage time are obtained by solving the associated backward Kolmogorov equation and Pontryagin *** validity of the proposed procedure is tested by applying it to an example and comparing the numerical results with those from Monte Carlo simulation.

关键词： Reliability Fkst passage time quasi integrable and non-resonant Hamiltonian systems Fractional Gauss noise

Assessing the prognosis of cirrhotic patients in the intensive care unit:What we know and what we need to know better

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World Journal of Hepatology 2021年第10期13卷 1341-1350页

作者： fernando da Silveira Pedro H R Soares Luana q Marchesan Roberto S A da Fonseca Wagner L Nedel Programa de Pos-Graduacao em Pneumologia Universidade Federal do Rio Grande do SulPorto Alegre 91430835Brazil Intensive Care Unit Grupo Hospitalar ConceiçãoPorto Alegre 91430835Brazil Programa de Pos-Graduacao em Neurociencias Universidade Federal do Rio Grande do SulPorto Alegre 91430835Brazil Programa de Pos-Graduacao em Ciencias da Saude Universidade Federal de Santa MariaSanta Maria 97105900Brazil Programa de Pos-Graduacao em Bioquimica Universidade Federal do Rio Grande do SulPorto Alegre 91430835Brazil

Critically ill cirrhotic patients have high in-hospital mortality and utilize significant health care resources as a consequence of the need for multiorgan *** this fact,their mortality has decreased in recent decades due to improved care of critically ill ***-on-chronic liver failure(ACLF),sepsis and elevated hepatic scores are associated with increased mortality in this population,especially among those not eligible for liver *** score is superior to another in the prognostic assessment of these patients,and both liver-specific and intensive care unit-specific scores have satisfactory predictive *** sequential assessment of the scores,especially the Sequential Organ Failure Assessment(SOFA)and Chronic Liver Failure Consortium(CLIF)-SOFA scores,may be useful as an auxiliary tool in the decision-making process regarding the benefits of maintaining supportive therapies in this population.A CLIF-ACLF>70 at admission or at day 3 was associated with a poor prognosis,as well as SOFA score>19 at baseline or increasing SOFA score>*** studies addressing the prognostic assessment of these patients are necessary.

关键词： Cirrhosis Extrahepatic organ failure Organ replacement therapy Mortality Prognostic scores Chronic Liver Failure Consortium-Sequential Organ Failure Assessment Sequential Organ Failure Assessment Model for End-stage Liver Disease

Improvement of Fracture Toughness Lanthanum Zirconate

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材料工程 2006年第5期34卷 51-56,62页

作者： LI J DAI H LI q ZHONG X H CAO X q Key Lab of Rare Earth Chemistry and Physics Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China GraduateSchool of the Chinese Academy of Sciences Beijing 100049 China

La2Zr2O7 （LZ） is a promising thermal barrier coating material for the high temperature applications. The fracture toughness and microhardness of nanocrystalline LZ （n-LZ）, microcrystalline LZ （m-LZ） and LZ-5mol%8YSZ （LZ-5-8YSZ） composite （8YSZ for zirconia stabilized by 8 mol% ytrria） were studied. The n-LZ had a thermal expansion coefficient of （9.6±0.4）×10 -6 K -1 （200～1000℃） and fracture toughness of （1.98±0.07） MPa·m 1/2 which are obviously higher than those of the m-LZ （（9.1±0.4）×10 -6 K -1 and （1.40±0.23） MPa·m 1/2, respectively）, indicating that nanofication was an efficient way to increase the toughness and thermal expansion coefficient of LZ. The composite LZ-5-8YSZ had a higher fracture toughness （（1.88±0.30） MPa·m 1/2） than LZ, which was close to that of 8YSZ densified by superhigh pressure （SHP）.

关键词： ceramics nanostructure fracture toughness thermal expansion

NOTE ON THE VIRIAL THEOREM

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Acta Mechanica Sinica 1998年第1期14卷 76-77页

作者： q.K.Ghori GIK Institute of Engineering Sciences & Technology TopiNWFPPakistan

Poincaré's formalism is used to develop a variant of the usual virial theorem in which the time average of the equation of motion of a certain function is expressed in terms of the generalized Poisson brackets.

关键词： analytical mechanics virial theorem Poincaré's formalism