检索结果-南通市图书馆

Mechanical force drives the polarization and orientation of cells

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2019年第2期35卷 275-288页

作者： Shijie He Xiaomeng Li baohua ji Center for Engineering in Medicine Massachusetts General Hospital Harvard Medical School Boston MA 02114 USA Department of Applied Mechanics School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China

Collective cells are organized to form specific patterns which play important roles in various physiological and pathological processes, such as tissue morphogenesis, wound healing, and cancer invasion. Compared to single cell behaviors, which has been intensively studied from many aspects (cell migration, adhesion, polarization, proliferation, etc.) and at various scales (molecular, subcellular, and cellular), the multiple cell behaviors are relatively less understood, particularly in a quantitative manner. In this paper, we will present our recent studies of collective polarization and orientation of multiple cells through both experimental measurement and theoretical modeling, including those cell behaviors on/in 2D and 3D substrate/tissue. We find that the collective cell behaviors, including polarization, alignment and migration are closely related to local stress states in cell layer or tissue, which demonstrate the crucial roles of mechanical forces in the living organisms. Specifically, the cells prefer to polarize and align along the maximum principal stress in the cell layer, and the aspect ratio of cell increases with the in-plane maximum shear stress, suggesting that the maximum shear stress is the underlying driving force of cell polarization and orientation. This theory of stress-driven cell behaviors of polarization and orientation provides a new perspective for understanding cell behaviors in living organisms and the guideline for tissue engineering in biomedical applications.

关键词： Collective cell behaviors Cell polarization Cell alignment Quantification Cell mechanosensing

Mechanics of water pore formation in lipid membrane under electric field

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第2期33卷 234-242页

作者： Bing Bu Dechang Li jiajie Diao baohua ji Biomechanics and Biomaterials Laboratory Department of Applied MechanicsBeijing Institute of Technology Department of Cancer Biology College of MedicineUniversity of Cincinnati

Transmembrane water pores are crucial for substance transport through cell membranes via membrane fusion, such as in neural communication. However, the molecular mechanism of water pore formation is not clear. In this study, we apply all-atom molecular dynamics and bias-exchange metadynamics simulations to study the process of water pore formation under an electric field. We show that water molecules can enter a membrane under an electric field and form a water pore of a few nanometers in diameter. These water molecules disturb the interactions between lipid head groups and the ordered arrangement of lipids. Following the movement of water molecules, the lipid head groups are rotated and driven into the hydrophobic region of the membrane. The reorientated lipid head groups inside the membrane form a hydrophilic surface of the water pore. This study reveals the atomic details of how an electric field influences the movement of water molecules and lipid head groups, resulting in water pore formation.

关键词： Cell membrane Membrane fusion Water pore formation Electric field Molecular dynamics simulation

Editorial:Mechanics of biological and bio-inspired materials

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2012年第1期2卷 8-11页

作者： baohua ji Biomechanics and Biomaterials Laboratory Department of Applied MechanicsBeijing Institute of Tech-nologyBeijing 100081China

The field of mechanics of biological and bio-inspired materials underwent an exciting development over the past several years, which made it stand at the cutting edge of both engineering mechanics and biomechanics. As an intriguing interdisciplinary research field, it aims at elucidating the fundamental principles in nature＇s design of strong, multi-functional and smart Materials by focusing on the assembly, deformation, stability and failure of the materials.

关键词： Editorial

CONCAVE BIOLOGICAL SURFACES FOR STRONG WET ADHESION

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2009年第6期22卷 593-604页

作者： Yewang Su baohua ji Yonggang Huang Kehchih Hwang Department of Engineering Mechanics Tsinghua University Beijing 100084 China Department of Applied Mechanics Beijing Institute of Technology Beijing 100081 China Department of Civil and Environmental Engineering Northwestern University Evanston IL 60208 USA

Plant leaves, insects and geckos are masters of adhesion or anti-adhesion by smartly designed refined surface structures with micro- and nano- ＇technologies＇. Understanding the basic principles in the design of the unique surface structures is of great importance in the manufacture or synthesis of micro- and nano- devices in MEMS or NEMS. This study is right inspired by this effort, focusing on the mechanics of wet adhesion between fibers having concave tips and a flat substrate via capillary forces. We show that the concave surface can effectively enhance the wet adhesion by reducing the effective contact angle of the fiber, firmly pinning the liquid bridge at its circumferential edge. A critical contact angle is identified below which the adhesion strength can achieve its maximum, being insensitive to the contact angle between the fiber and liquid. The analytical expression for the critical angle is derived. Then a tentative design for the profile of concave surfaces is proposed, considering the effects of chamfering size, deformation and buckling, etc. The effect of liquid volume on the wet adhesion of multiple-fiber system is also discussed.

关键词： biological surface wet adhesion contact shape concave surface robustness ad- hesion force

Effect of triple-phase contact line on contact angle hysteresis

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 1045-1050页

作者： YU Yang WU Qun ZHANG Kai ji baohua Biomechanics and Biomaterials Laboratory Department of Applied Mechanics School of Aerospace Engineering Beijing Institute of Technology Beijing 100081 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

Recent studies have shown that the triple-phase contact line has critical effect on the contact angle hysteresis of *** this study,patterned surfaces with various surface structures of different area fractions were prepared by electron etching on a silicon *** advancing angle,receding angle and hysteresis angle of these surfaces were *** experimental results showed that while the geometry of microstructure and contact line have a minor effect on the advancing angle,they have a significant effect on the receding angle and thus the hysteresis *** have shown that the effect of microstructure and the contact line can be described by a quantitative parameter termed the triple-phase line *** theoretical predictions were in good agreement with our experimental results.

关键词： contact angle hysteresis receding angle surface microstructure area fraction contact line ratio wetting

Protein conformational transitions coupling with ligand interactions:Simulations from molecules to medicine

在线全文

学校读者我要写书评

暂无评论

Medicine in Novel Technology and Devices 2019年第3期3卷 16-25页

作者： Dechang Li baohua ji Department of Engineering Mechanics Zhejiang UniversityHangzhou310027China Beijing Advanced Innovation Center for Biomedical Engineering Beijing100191China

The functions and activities of proteins are closely related to their structures and dynamics,and their interactions with *** of the mechanistic events of proteins’conformational transitions and interactions with ligands is crucially important to understand the functions and biological activities of proteins and thus to the design of novel inhibitors of the targeted *** this review article,taking two important systems as examples,i.e.,human immunodeficiency virus type 1 protease(HIV-1 PR)and adenylate kinase(AdK),and focusing on the molecular dynamics simulations of the conformational transitions of protein and the protein-ligand association/dissociation,we explain how the conformational transitions of proteins influence the interactions with their ligands,and how the ligands impact the function and dynamics of *** results of structural dynamics of HIV-1 PR and AdK and their interactions with ligands can help to understand the principle of conformational transitions of proteins,or the interactions of ligands to their biological targets,and thus provide meaningful message in chemistry and biology of drug design and discovery.

关键词： Conformational transition Protein-ligand interaction Drug design Molecular dynamics simulation HIV-1 protease Adenylate kinase

Pulling out a peptide chain from β-sheet crystallite: Propagation of instability of H-bonds under shear force

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第3期31卷 416-424页

作者： Changjian Xu Dechang Li Yuan Cheng Ming Liu Yongwei Zhang baohua ji Biomechanics and Biomaterials Laboratory Department of Applied Mechanics Beijing Institute of Technology Institute of High Performance Computing A*STAR CSIRO - Computational Informatics and Digital Productivity Flagship

Anti-parallel β-sheet crystallite as the main component of silk fibroin has attracted much attention due to its superior mechanical properties. In this study, we examine the processes of pulling a peptide chain from β-sheet crystallite using steered molecular dynamics simulations to investigate the rupture behavior of the crystallite. We show that the failure of β-sheet crystallite was accompanied by a propagation of instability of hydrogen-bonds （H-bonds） in the crystallite. In addition, we find that there is an optimum size of the crystallite at which the H-bonds can work cooperatively to achieve the highest shear strength. In addition, we find that the stiffness of loading device and the loading rates have significant effects on the rupture behavior of β-sheet crystallite. The stiff loading device facilitates the rebinding of the Hbond network in the stick-slip motion between the chains, while the soft one suppresses it. Moreover, the rupture force of β-sheet crystallites decreases with loading rate. Particularly, when the loading rate decreases to a critical value, the rupture force of the β-sheet crystallite becomes independent of the loading rates. This study provides atomistic details of rupture behaviors of β-sheet crystallite, and, therefore, sheds valuable light on the underlying mechanism of the superior mechanical properties of silk fibroin.

关键词： Silk fibroin β-Sheet crystallite - H-bondnetwork Molecular biomechanics Steered moleculardynamics

Cell traction force distribution and its implications in cell adhesion and migration

在线全文

学校读者我要写书评

暂无评论

医用生物力学 2013年第S1期28卷 33-35页

作者： Shijie He Yewang Su baohua ji Biomechanics and Biomaterials Lab School of Aerospace EngineeringBeijing Institute of Technology Departments of Civil and Environmental Engineering and Mechanical Engineering Northwestern University

Cell-matrix interaction is the key for understanding the cell behaviors,especially the mechanosensitivity of cell adhesion,cell migration and differentiation,*** are constantly probing,pushing and pulling on the surrounding extracellular *** cell-generated forces drive cell migration and tissue morphogenesis,and maintain the intrinsic mechanical tone of ***,knowledge of the spatial and temporal nature of these forces are essential to understanding when and where mechanical events come to play in both physiological and pathological ***,because of the complexity of cell geometry and insufficient

关键词： migration traction constantly physiological maintain surrounding intrinsic probing insufficient periphery

Local buckling analysis of biological nanocomposites based on a beam-spring model

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2015年第4期5卷 146-150页

作者： Zhiling Bai baohua ji Biomechanics and Biomaterials Laboratory Department of Applied Mechanics School of Aerospace Engineering Beijing Institute of Technology

Biological materials such as bone, tooth, and nacre are load-bearing nanocomposites composed of mineral and protein. Since the mineral crystals often have slender geometry, the nanocomposites are susceptible to buckle under the compressive load. In this paper, we analyze the local buckling behaviors of the nanocomposite structure of the biological materials using a beam-spring model by which we can consider plenty of mineral crystals and their interaction in our analysis compared with existing studies. We show that there is a transition of the buckling behaviors from a local buckling mode to a global one when we continuously increase the aspect ratio of mineral, leading to an increase of the buckling strength which levels off to the strength of the composites reinforced with continuous crystals. We find that the contact condition at the mineral tips has a striking effect on the local buckling mode at small aspect ratio, but the effect diminishes when the aspect ratio is large. Our analyses also show that the staggered arrangement of mineral plays a central role in the stability of the biological nanocomposites.

关键词： Biological materials Nanostructure Staggered arrangement Buckling behaviors Aspect ratio Composite materials