共查询到20条相似文献,搜索用时 109 毫秒
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台湾大学应用力学研究所于1993年12月8日—15日在台北举行现代力学研讨会,暨应用力学研宪所成立十周年庆祝大会等学术活动,邀请世界各国华人学者参加,到会代表近三百人.会议邀请大陆有关专家二十多人,其中包括学部委员五人:王仁、郑哲敏、张淑仪、黄克智、高镇同等教授.台大应用力学研究所的研究重点包括结构动力学、破坏力学、刚体动力学、流体动力学、工程声学、生物力学、太空力学等等,研讨会也涉及上述多个方面.会议以大会邀请报告,分组邀请报告,以及论文报告等三种方式进行,报告论文约200篇.第一次全体大会上,易家训教授… 相似文献
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楔环连接用于连接两个简体,在一些武器结构上已实际应用。研究和认识楔环连接结构的静、动力学行为,不仅有助于提高人们对该种结构的设计水平,也可以加强人们对诸如此类复杂结构中各种力学规律的认识,促进学科发展。 相似文献
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研究了固体炸药PBX代用材料D-90031的微观结构、压制过程中产生的原生缺陷形态,以及动态力学行为和破坏特征。采用数字图像分析技术、纳米力学测试系统,以及分离式霍普金森压杆(SHPB)实验和落锤冲击技术,获得了微观结构特点、各组分的硬度和弹性模量、动态性能,以及碎片的尺寸分布规律和材料的破坏形式。研究发现,晶粒的形态随外载的作用而改变,晶粒沿垂直加载方向伸长,材料的碎块尺寸满足一定的规律。研究结果对于深入认识固体炸药的性能与微观结构的关系具有一定的指导意义。 相似文献
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“舌簧片振动法”测杨氏模量 总被引:5,自引:0,他引:5
对材料的杨氏模量的测定历来是研究材料的力学性质以及结构的重要手段,因此,实验科学工作者在不断地探索用各种不同的实验方法来测量材料的杨氏模量,本文介绍国外(日本)常用的一种测量的方法-舌簧片振动法。 相似文献
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简述了我校物理系进行力学综合课程建设的基本思想和措施,以及建立将普通物理力学、理论力学和量子力学基础综合成一门课程的新的教学内容结构体系的具体做法.这样做,不但大大减少了重复内容和课时。而且有助于学生从整体上把握力学理论的基本框架,有助于培养学生的综合研究能力和创新能力。 相似文献
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针对大腔体静高压装置中的多级八面体压腔,分析了两种不同加载结构的力的传递, 建立了高压发生效率的力学关系.室温下,采用定点标压法(Bi, ZnTe, ZnS, GaAs)分别标定了14/8, 12/6和10/4三种二级6-8型大腔体静高压组装的腔体压力, 定量地讨论了力学结构和末级压砧硬度对八面体压腔高压发生效率的影响. 实验结果表明,力学结构和末级压砧硬度都是影响高压发生效率的重要因素, 且力学结构对高压发生效率的影响更大.其中,腔体的几何结构越大,高压发生效率越高; 6-8型加载结构的高压发生效率高于2-6-8型加载结构;在八面体压腔内的压力接近末级压砧的维氏硬度时, 末级压砧硬度越大,高压发生效率越高,所能获得的腔体压力越大. 相似文献
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Atomic force microscopy probing of cell elasticity 总被引:3,自引:0,他引:3
Kuznetsova TG Starodubtseva MN Yegorenkov NI Chizhik SA Zhdanov RI 《Micron (Oxford, England : 1993)》2007,38(8):824-833
Atomic force microscopy (AFM) has recently provided the great progress in the study of micro- and nanostructures including living cells and cell organelles. Modern AFM techniques allow solving a number of problems of cell biomechanics due to simultaneous evaluation of the local mechanical properties and the topography of the living cells at a high spatial resolution and force sensitivity. Particularly, force spectroscopy is used for mapping mechanical properties of a single cell that provides information on cellular structures including cytoskeleton structure.
This entry is aimed to review the recent AFM applications for the study of dynamics and mechanical properties of intact cells associated with different cell events such as locomotion, differentiation and aging, physiological activation and electromotility, as well as cell pathology. Local mechanical characteristics of different cell types including muscle cells, endothelial and epithelial cells, neurons and glial cells, fibroblasts and osteoblasts, blood cells and sensory cells are analyzed in this paper. 相似文献
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A model for active elements in cochlear biomechanics 总被引:11,自引:0,他引:11
A linear, mathematical model of cochlear biomechanics is presented in this paper. In this model, active elements are essential for simulating the high sensitivity and sharp tuning characteristic of the mammalian cochlea. The active elements are intended to represent the motile action of outer hair cells; they are postulated to be mechanical force generators that are powered by electrochemical energy of the cochlear endolymph, controlled by the bending of outer hair cell stereocilia, and bidirectionally coupled to cochlear partition mechanics. The active elements are spatially distributed and function collectively as a cochlear amplifier. Excessive gain in the cochlear amplifier causes spontaneous oscillations and thereby generates spontaneous otoacoustic emissions. 相似文献
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Lekka M Pogoda K Gostek J Klymenko O Prauzner-Bechcicki S Wiltowska-Zuber J Jaczewska J Lekki J Stachura Z 《Micron (Oxford, England : 1993)》2012,43(12):1259-1266
The major characteristics of cancer metastasis is the ability of the primary tumor cells to migrate by way of the blood or lymph vessels and to form tumors at multiple, distant sites. There are evidences that cancer progression is characterized by disruption and/or reorganization of cytoskeleton (i.e. cellular scaffold). This is accompanied by various molecular alterations influencing the overall mechanical resistance of cells. Current approach in diagnosis focuses mainly on microbiological, immunological, and pathological aspects rather than on the biomechanics of diseases. The determination of mechanical properties of an individual living cell has became possible with the development of local measurement techniques, such as atomic force microscopy, magnetic or optical tweezers. The advantage of them lies in the capability to measure living cells at a single cell level and in liquid conditions, close to natural environment. Here, we present the studies on mechanical properties of single cells originating from various cancers. The results show that, independently of the cancer type (bladder, melanoma, prostate, breast and colon), single cells are characterized by the lower Young's modulus, denoting higher deformability of cancerous cells. However, the obtained Young's modulus values were dependent on various factors, like the properties of substrates used for cell growth, force loading rate, or indentation depth. Their influence on elastic properties of cells was considered. Based on these findings, the identification of cancerous cells based on their elastic properties was performed. These results proved the AFM capability in recognition of a single, mechanically altered cell, also in cases when morphological changes are not visible. The quantitative analysis of cell deformability carried out using normal (reference) and cancerous cells and, more precisely, their characterization (qualitative and quantitative) can have a significant impact on the development of methodological approaches toward precise identification of pathological cells and would allow for more effective detection of cancer-related changes. 相似文献
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This paper aims to provide a review and critical analysis of the state of the art concerning crowd-structure interaction phenomena on footbridges. The problem of lateral vibrations induced by synchronised pedestrians, namely the Synchronous Lateral Excitation, is specifically addressed. Due to the multi-physic and multi-scale nature of the complex phenomenon, several research fields can contribute to its study, from structural engineering to biomechanics, from transportation engineering to physics and applied mathematics. The different components of the overall coupled dynamical system – the structure, the crowd and their interactions – are separately analysed from both a phenomenological and modelling point of view. A special attention is devoted to those models, which explicitly account for the interaction between mechanical and living systems. 相似文献
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A worm-like chain model based on a spectrin network is employed to study the biomechanics of red blood cells. Coarse-grained molecular dynamics simulations are performed to obtain a stable configuration free of external loadings. We also discuss the influence of two parameters: the average bending modulus and the persistence length. The change in shape of a malaria-infected red blood cell can contribute to the change in its molecular-based structure. As the persistence length of the membrane network in the infected red blood cell decreases, the deformability decreases and the biconcave shape is destroyed. The numerical results are comparable with previously reported experimental results. The coarse-grained model can be used to study the relationship between macro-mechanical properties and molecular-scale structures of cells. 相似文献
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《中国物理 B》2021,30(9):90505-090505
Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression, e.g., osteogenic differentiation of embryonic stem cells was facilitated on stiffer substrates, indicating that the mechanical signals greatly affect both early and terminal differentiation of embryonic stem cells. However, the effect of anisotropy on cell migration dynamics, in particular, in terms of acceleration profiles which is important for recognizing dynamics modes of cell migration and analyzing the regulation mechanisms of microenvironment in mechanical signal transmission, has not been systematically investigated. In this work, we firstly rigorously investigate and quantify the differences between persistent random walk and anisotropic persistent random walk models based on the analysis of cell migration trajectories and velocity auto-covariance function, both qualitatively and quantitatively. Secondly, we introduce the concepts of positive and negative anisotropy based on the motility parameters to study the effect of anisotropy on acceleration profiles, especially the nonlinear decrease and non-monotonic behaviors. We particularly elaborate and discuss the mechanisms, and physical insights of non-monotonic behaviors in the case of positive anisotropy,focusing on the force exerted on migrating cells. Finally, we analyze two types of in vitro cell migration experiments and verify the universality of nonlinear decrease and the consistence of non-monotonic behaviors with numerical results.We conclude that the anisotropy of microenvironment is the cause of the non-monotonic and nonlinear dynamics, and the anisotropic persistent random walk can be as a suitable tool to analyze in vitro cell migration with different combinations of motility parameters. Our analysis provides new insights into the dynamics of cell migration in complex microenvironment,which also has implications in tissue engineering and cancer research. 相似文献
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Cell mechanical properties are fundamental to the organism but remain poorly understood. We report a comprehensive phenomenological framework for the complex rheology of single fibroblast cells: a superposition of elastic stiffening and viscoplastic kinematic hardening. Despite the complexity of the living cell, its mechanical properties can be cast into simple, well-defined rules. Our results reveal the key role of crosslink slippage in determining mechanical cell strength and robustness. 相似文献
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Fabry B Maksym GN Hubmayr RD Butler JP Fredberg JJ 《Journal of magnetism and magnetic materials》1999,194(1):120-125
Magnetic twisting cytometry (MTC) measures cellular mechanical properties, such as cell stiffness and viscosity, by applying mechanical stress to specific cell surface receptors via ligand-coated ferromagnetic beads. MTC measures simultaneously the rotation of approximately 50,000 beads attached to 20,000 - 40,000 cells. Here we show direct evidence of heterogeneous bead behavior and examine its consequences in the interpretation of cell mechanical properties. 相似文献
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Generation of doughnut laser beams by use of a liquid-crystal cell with a conversion efficiency near 100% 总被引:2,自引:0,他引:2
We present a novel technique for producing a doughnut laser beam by use of a liquid-crystal cell. It is demonstrated that the liquid-crystal cell exhibits an efficiency in energy conversion near 100%. One of the main advantages of this method is its capability of dynamic switching between a Gaussian mode and a doughnut mode of different topological charges. The liquid-crystal cell is also dynamically tunable over the visible and near-infrared wavelength range. These advantages make the device appealing for laser trapping methods used in single-molecule biomechanics and for optical guiding of cold atoms. 相似文献
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Tumor growth and metastasis are ultimately mechanical processes involving cell migration and uncontrolled division. Using a 3D discrete model of cells, we show that increased compliance as observed for cancer cells causes them to grow at a much faster rate compared to surrounding healthy cells. We also show how changes in intercellular binding influence tumor malignancy and metastatic potential. These findings suggest that changes in the mechanical properties of cancer cells is the proximate cause of uncontrolled division and migration and various biochemical factors drive cancer progression via this mechanism. 相似文献