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ON ANALYSIS OF THE STEADY FLOW IN AN IRRECTANGULARPARALLEL-PLATE FLOW CHAMBER

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Applied Mathematics and Mechanics(English Edition) 1998年第9期19卷 851-859页

作者：覃开荣姜伟元李惜惜柳兆荣 biomechanics Laboratory Fudan University Shanghai P. R. China institute of Applied Mathematics and Mechanics Shanghai P. R. China

The parallel-plate flow chamber (PPFC), of which the height is far smaller than its own length and width, is one of the main apparatus for the in vitro study of the mechanical behaviors of cultured cells at the bottom of PPFC undergoing shear stress. The PPFC of which the upper and lower plates are rectangular is usually used by research workers, and the flow field in this kind of PPFC (except for the regions near the entrance and exit) is uniform([1]), so only the effect the shear stress with one value has on cultured cells can be observed during each experiment. A kind of PPFC of which the upper and lower plates are not rectangular is proposed in this paper. The distributions of the velocities inside and the shear stresses at the bottom of the chamber are given by analyzing the flow field of the steady flow in the PPFC. The results show that the mechanical behaviors of cultured cells undergoing the shear stresses with various values may be simultaneously observed by the use of this kind of irrectangular PPFC. The theoretical and experimental results obtained by Ultrasonic Doppler Technique show good agreement.

关键词： irrectangular parallel-plate flow chamber shear stress steady flow cell's mechanical behaviors

Regulation of shear stress on rolling behaviors of HL-60 cells on P-selectin

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Science China(Physics,Mechanics & Astronomy) 2014年第10期57卷 1998-2006页

作者： LING YingChen FANG Ying YANG XiaoFang LI QuHuan LIN QinYong WU JianHua School of Life Sciences Sun Yat-Sen University School of Bioscience and Bioengineering South China University of Technology institute of biomechanics South China University of Technology

Circulating leukocytes in trafficking to the inflammatory sites, will be first tether to, and then roll on the vascular surface. This event is mediated through specific interaction of P-selectin and P-selectin glycoprotein ligand-1 （PSGL-1）, and regulated by hemodynamics. Poor data were reported in understanding P-selectin-mediated rolling. With the flow chamber technique, we herein observed HL-60 cell rolling on P-selectin with or without 3% Ficoll at various wall shear stresses from 0.05 to 0.4 dyn/cm：. The results demonstrated that force rather than transport regulated the rolling, similar to rolling on L- and E-selectin. The rolling was accelerated quickly by an increasing force below the optimal shear threshold of 0.15 dyn/cm2 first and then followed by a slowly decelerating phase starting at the optimum, showing a catch-slip transition and serving as a mechanism for the rolling. The catch-slip transition was completely reflected to the tether lifetime and other rolling parameters, such as the mean and fractional stop time. The narrow catch bond regime stabilized the rolling quickly, through steeply increasing frac- tional stop time to a plateau of about 0.85. Data presented here suggest that the low shear stress threshold serves as a mecha- nism for most cell rolling events through P-selectin.

关键词： P-selectin P-selectin glycoprotein ligand-1 cell adhesion shear stress

The effects of total ankle replacement on ankle joint mechanics during walking

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Journal of Sport and Health Science 2017年第3期6卷 340-345页

作者： Henry Wang Scott R.Brown biomechanics Laboratory School of KinesiologyBall State University Sports Performance Research institute New Zealand(SPRINZ) Auckland University of Technology

Background:End-stage ankle arthritis impairs joint function and patients' *** ankle replacement is a surgical procedure to treat severe ankle *** Talaris Anatomic Ankle^(TM)(STAA) was designed to mimic the normal ankle anatomy and flexion/extension of the ankle *** purpose of this study was to examine the effect of an STAA ankle replacement on ankle joint function and mechanics during ***:Five patients with end-stage unilateral ankle arthritis were *** performed level walking in a laboratory setting on 2occasions,prior to and 3 months after the STAA ankle *** Orthopedic Foot and Ankle Society(AOFAS) hindfoot score was obtained.A 12-camera motion capture system was used to perform walking *** temporo-spatial parameters and ankle joint mechanics were *** Student's t tests and non-parametric Wilcoxon matched tests were performed to examine the differences in biomechanical variables between the pre-and post-surgery walking ***:Compared to the pre-surgical condition,at 3 months of post-STAA surgery,patients experienced greater improvement in AOFAS hindfoot score(p = 0.0001);the STAA ankle demonstrated a 31% increase in ankle joint excursion(p = 0.045),a 22% increase in ankle plantarflexor moment(p = 0.075),a 60% increase in ankle power absorption(p = 0.023),and a 68% increase in ankle power production(p = 0.039).Patients also demonstrated a 26% increase in walking speed(p = 0.005),a 20% increase in stride length(p = 0.013),a 15% decrease in double support time(p = 0.043),and a 5% decrease in total stance time(p = 0.055).Conclusion:Three months after surgeries,the STAA patients experienced improvements in ankle function and gait *** STAA ankle demonstrated improved ankle mechanics during daily activities such as walking.

关键词： Ankle mechanics AOFAS score Arthritis Gait analysis Total ankle replacement Walking

Collective migrations in an epithelial-cancerous cell monolayer

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Acta Mechanica Sinica 2021年第5期37卷 773-784,I0001页

作者： Jian‑Qing Lv Peng‑Cheng Chen Liu‑Yuan Guan Wojciech T.Góźdź Xi‑Qiao Feng Bo Li institute of biomechanics and Medical Engineering Applied Mechanics LaboratoryDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China institute of Physical Chemistry Polish Academy of SciencesKasprzaka 44/5201‑224 WarsawPoland

Collective cell migration is extensively observed in embryo development and cancer *** these processes,the interactions between cells with distinct identities and fates are of importance for boundary formation and host defense against *** this paper,we explore the collective dynamics of a two-dimensional cell mixing monolayer consisting of non-tumorigenic mammary epithelial cells and breast cancer *** show that the epithelial-cancerous cell mixing system displays unique sorting *** epithelial cells aggregate to form scattered clusters,which perform random motion with simultaneous translation and rotation,strikingly distinct from the classical persistent random walk of individual migratory *** motility of cancer cells is markedly promoted by the epithelial clusters,exhibiting remarkable contact enhancement of locomotion.A discrete model based on the Johnson-Kendall-Roberts contact mechanics is proposed to identify the influence of intercellular interactions,active migration forces and cell-substrate friction forces on the collective cell *** findings could advance our understanding of many biological processes,such as cancer metastasis and tissue morphogenesis.

关键词： Collective cells Cell mixing Dynamics Cell-cell interaction

Self-assembly of lipids and nanoparticles in aqueous solution:Self-consistent field simulations

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Theoretical & Applied Mechanics Letters 2012年第1期2卷 22-26页

作者： Weihua Xie Guangkui Xu Xiqiao Feng institute of biomechanics and Medical Engineering Department of Engineering MechanicsTsinghua UniversityBeijing 100084China

Self-assembled nanostructures of lipids and nanoparticles hold great promise for applications in such fields as nanomedicine. This paper uses the self-consistent field theory to investigate the self-assembly behavior of lipid molecules and nanoparticles with different shapes in an aqueous solution. It is found that the lipid molecules can form monolayered and bilayered nanostructures around the nanopartieles with different shapes （e.g., triangular, square, hexagonal and octangular）. With decreasing the size of nanoparticles or increasing the number of polygon edges, the shape of lipid layers will approach an approximately spherical shape. These findings may help to predict and design novel drug delivery nanocarriers.

关键词： liposome nanoparticle self-assembly self-consistent field theory drug delivery

Effect of minocycline and its nano-formulation on central auditory system in blast-induced hearing loss rat model

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Journal of Otology 2023年第1期18卷 38-48页

作者： Venkatesan Perumal Arun Reddy Ravula Ningning Shao Namas Chandra Center for Injury biomechanics Materialsand MedicineDepartment of Biomedical EngineeringNew Jersey Institute of TechnologyNewarkNJ07102USA

Blast injuries are common among the military service members and *** of the devastating effects of blast wave induced TBI is either temporary or permanent hearing *** hearing loss using minocycline is restricted by optimal drug concentration,route of administration,and its ***,therapeutic approach using novel therapeutic delivery method is in great *** the different delivery methods,nanotechnology-based drug delivery is desirable,which can achieve longer systemic circulation,pass through some biological barriers and specifically targets desired *** current study aimed to examine therapeutic effect of minocycline and its nanoparticle formulation in moderate blast induced hearing loss rat model through central auditory *** *** nanoparticle at reduced dose and frequency than regularly administered toxic *** moderate blast exposure,rats had hearing impairment as determined by ABR at 7-and 30-days post *** chronic condition,free minocycline also showed the significant reduction in ABR *** central auditory system,it is found in this study that minocycline nanoparticles ameliorate excitation in inferior colliculus;and astrocytes and microglia activation after the blast exposure is reduced by minocycline nanoparticles *** study demonstrated that in moderate blast induced hearing loss,minocycline and its nanoparticle formulation exhibited the optimal therapeutic effect on the recovery of the ABR impairment and a protective effect through central auditory *** conclusion,targeted and non-targeted nanoparticle formulation have therapeutic effect on blast induced hearing loss.

关键词： Minocycline Nanoparticle Hearing loss Blast injury and targeted drug delivery

Soft substrate and decreased cytoskeleton contractility promote coupling and morphology maintenance of pluripotent stem cells

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Acta Mechanica Sinica 2021年第10期37卷 1520-1529,I0002页

作者： Meihong Lu Jialing Cao Yuanyuan Zhai Peng Zhao Jie Yao Yan Gong Jing Du Yubo Fan Key Laboratory for biomechanics and Mechanobiology of the Ministry of Education Institute of Nanotechnology for Single Cell AnalysisBeijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing100083China institute of biomechanics and Medical Engineering Department of Mechanical EngineeringSchool of AerospaceTsinghua UniversityBeijing100084China Sino-French Engineer School Beihang UniversityBeijing100083China School of Material Science&Engineering Beijing Institute of Fashion TechnologyBeijing100029China

The mechanical microenvironment affects the morphology and mechanical properties of cells, and it also plays an important role in cell functions. Pluripotent stem cells (PSCs) grow as multicellular colonies, and the coupling effects of cell–cell and cell-extracellular matrix interactions are complex but necessary for the formations and functions of tissues. This paper uses the finite element method to establish a three-dimensional calculation model of a pair of deformed PSCs in contact with each other and considers the growth and depolymerization of actin filaments. Then the effects of substrate stiffness on the morphology of cells and nuclei and the rearrangement of cytoskeleton are demonstrated. As the substrate becomes softer, the nuclei become loose and round, and the actin filaments will be assembled at a lower level, which could promote the formation of compacted cell colony while having a positive effect on maintaining pluripotency and inducing reprogramming efficiency. In addition, stronger activation of cytoskeleton contractility will compress the cytoplasm and nuclei. The cell mechanics model proposed in this paper provides a strategy for studying the cell morphology and cytoskeleton response of the two-cell system under different biophysical stimuli, and also lays the foundation for the further research on more mechanical factors of cell pluripotency.

关键词： Pluripotent stem cells Morphology Cell model Mechanical stimuli

Numerical Analyses of Idealized Total Cavopulmonary Connection Physiologies with Single and Bilateral Superior Vena Cava Assisted by an Axial Blood Pump

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Computer Modeling in Engineering & Sciences 2018年第8期116卷 215-228页

作者： Xudong Liu Yunhan Cai Bing Jia Shengzhang Wang Guanghong Ding institute of biomechanics Department of Aeronautics and AstronauticsFudan UniversityShanghai200433China. Cardiovascular Center Children’s HospitalFudan UniversityShanghai201102China.

Our study evaluated the hemodynamic performance of an axial flow blood pump surgically implanted in idealized total cavopulmonary connection(TCPC)*** blood pump was designed to augment pressure from the inferior vena cava(IVC)to the pulmonary *** Fontan procedures with single and bilateral superior vena cava(SVC)were compared to fit the mechanical supported TCPC *** fluid dynamics(CFD)analyses of two Pump-TCPC models were performed in the ***-flow characteristics,energy efficiency,fluid streamlines,hemolysis and thrombosis analyses were *** simulations indicate that the pump produces pressure generations of 1 mm to 24 mm Hg for rotational speeds ranging from 2000 RPM to 5000 RPM and flow rates of 2 LPM to 4 *** surgical models incorporated with the pump were found to be insignificant in pressure augmentation and energy *** risk assessment of blood trauma and thrombosis generation was evaluated representatively through blood damage index(BDI),particle resident time(PRT)and relative resistant time(RRT).The hemolysis and thrombosis analyses declare the advantage of the pump supported bilateral SVC surgical scheme in balancing flow distribution and reducing the risk of endothelial cell destruction and trauma generation.

关键词： Computational fluid dynamics total cavopulmonary connection bilateral superior vena cava axial flow blood pump blood trauma thrombosis probability

Editorial:Mechanics of biological and bio-inspired materials

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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