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Numerical study of opposed zero-net-mass-flow jet-induced erythrocyte mechanoporation

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Applied Mathematics and mechanics(English Edition) 2022年第11期43卷 1763-1776页

作者： xinyue LIU Jinfang AI Jun xIE Guohui HU Shanghai Institute of Applied Mathematics and mechanics School of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringCollaborative Innovation Center for the Marine Artificial IntelligentShanghai UniversityShanghai 200072China Zhejiang Lab Hangzhou 311121China

With the advantages of biosafety and efficiency,increasing attention has been paid to the devices for gene and macromolecular drug delivery based on *** transient pore formation on the cell membrane allows cargo transportation when the membrane areal strain is beyond the critical pore value and below the lysis tension *** on this principle,we propose a method to apply the proper fluid stress on cells moving in a microchannel under the action of zero-net-mass-flux(ZNMF)*** this study,an immersed finite element method(IFEM)is adopted to simulate the interaction between the cells and the fluid fields so as to investigate the cell movement and deformation in this mechanoporation *** evaluate the efficiency of the cargo delivery,a pore integral is defined as the mean pore rate when the cell passes through the jet *** analyzing the effects of the parameters,including the pressure gradient along the microchannel,the jet amplitude,and the jet frequency,on the pore integrals,a group of optimized parameters for cargo delivery efficiency are ***,the stability and safety of this system are analyzed in *** results are helpful in designing the mechanoporation devices and improving their efficiency of drug delivery.

关键词： drug delivery membrane mechanoporation zero-net-mass-flux(ZNMF)jet immersed finite element method(IFEM)

Control of surface wettability via strain engineering

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Acta Mechanica Sinica 2013年第4期29卷 543-549页

作者： Wei xiong Jefferson Zhe Liu Zhi-Liang Zhang Quan-Shui Zheng Department of Engineering mechanics and center for Nano and Micro mechanics Tsinghua University Department of Mechanical and Aerospace Engineering Monash University Department of Structural Engineering Norwegian University of Science and Technology (NTNU)

Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sam- ple material and molecular dynamic simulations, we demon- strate that strain engineering can serve as an effective way to control the surface wettability. The contact angles 0 of water droplets on a graphene vary from 72.5° to 106° under biaxial strains ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface （at zero strain）, the variation of 0 upon the applied strains is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the strains. In light of the inherent dependence of the contact an- gle on liquid-solid interfacial energy, we develop an analytic model to show the cos 0 as a linear function of the adsorption energy Eads of a single water molecule over the substrate sur- face. This model agrees with our molecular dynamic results very well. Together with the linear dependence of Eads on bi- axial strains, we can thus understand the effect of strains on the surface wettability. Thanks to the ease of reversibly ap- plying mechanical strains in micro/nano-electromechanical systems, we believe that strain engineering can be a promis- ing means to achieve the reversibly control of surface wetta- bility.

关键词： Wettability ~ Strain engineering ~ Molecular dy-namics simulation

Corrections to: Structural Optimization of Fiber-Reinforced Material Based on Moving Morphable Components (MMCs)

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Acta Mechanica Solida Sinica 2022年第4期35卷 716-717页

作者： Zhi Sun Ziwen Song Junfu Song Haiyan Li xu Guo State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsInternational Research Center for Computational MechanicsDalian University of TechnologyDalian116023China

Corrections to:Acta Mechanica Solida Sinica https://***/10.1007/s10338-021-00305-0 During production of the article unfortunately several typesetting mistakes have been *** Eq.(17).

关键词： mistake Morph MMCs

Development of a space cold atom clock

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National Science Review 2020年第12期7卷 1828-1836页

作者： Wei Ren Tang Li Qiuzhi Qu Bin Wang Lin Li Desheng Lü Weibiao Chen Liang Liu Key Laboratory of Quantum Optics and center of Cold Atom Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences Research center of Space Laser Information Technology Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences

Atomic clocks with cold atoms play important roles in the field of fundamental physics as well as primary frequency *** such cold atom clocks in space paves the way for further exploration in fundamental physics,for example dark matter and general *** developed a space cold atom clock(SCAC),which was launched into orbit with the Space Lab TG-2 in *** it deorbited with TG-2 in2019,the SCAC had been working continuously for almost 3 *** the period in orbit,many scientific experiments and engineering tests were *** this article,we summarize the principle,development and in-orbit *** works provide the basis for construction of a space-borne time-frequency system in deep space.

关键词： cold atom clock in orbit microgravity fundamental physics

Large eddy simulation of high-Reynolds-number atmospheric boundary layer flow with improved near-wall correction

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Applied Mathematics and mechanics(English Edition) 2020年第1期41卷 33-50页

作者： Shengjun FENG xiaojing ZHENG Ruifeng HU Ping WANG Key Laboratory of mechanics on Disaster and Environment in Western China Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Research center for Applied mechanics School of Mechano-Electronic EngineeringXidian UniversityXi’an 710071China

It is highly attractive to develop an efficient and flexible large eddy simulation(LES)technique for high-Reynolds-number atmospheric boundary layer(ABL)simulation using the low-order numerical scheme on a relatively coarse grid,that could reproduce the logarithmic profile of the mean velocity and some key features of large-scale coherent structures in the outer *** this study,an improved near-wall correction scheme for the vertical gradient of the resolved streamwise velocity in the strain-rate tensor is proposed to calculate the eddy viscosity coefficient in the subgrid-scale(SGS)*** LES code is realized with a second-order finite-difference scheme,the scale-dependent dynamic SGS stress model,the equilibrium wall stress model,and the proposed correction ***-high-Reynolds-number ABL flow simulation under the neutral stratification condition is conducted to assess the performance of the method in predicting the mean and fluctuating characteristics of the rough-wall *** is found that the logarithmic profile of the mean streamwise velocity and some key features of large-scale coherent structures can be reasonably predicted by adopting the proposed correction method and the low-order numerical scheme.

关键词： atmospheric boundary layer near-wall correction large-eddy simulation(LES) very-large-scale motion

Molecular transport under extreme confinement

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Science China(Physics,mechanics & Astronomy) 2022年第6期65卷 1-10页

作者： FengChao Wang JianHao Qian JingCun Fan JinChuan Li HengYu xu HengAn Wu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China

Mass transport through the nanoporous medium is ubiquitous in nature and *** the macroscale transport phenomena which have been well understood by the theory of continuum mechanics,the relevant physics and mechanics on the nanoscale transport still remain *** developments in fabrication of slit-like nanocapillaries with precise dimensions and atomically smooth surfaces have promoted the fundamental research on the molecular transport under extreme *** this review,we summarized the contemporary progress in the study of confined molecular transport of water,ions and gases,based on both experiments and molecular dynamics *** liquid exhibits a pronounced layered structure that extends over several intermolecular distances from the solid surface,which has a substantial influence on static properties and transport behaviors under *** studies have also shown that those molecular details could provide some new understanding on the century-old classical theory in this field.

关键词： confined mass transport nanocapillary solid-liquid interface confinement effect

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Imperfection sensitivity of mechanical properties in soft network materials with horseshoe microstructures

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Acta Mechanica Sinica 2021年第7期37卷 1050-1062,I0001页

作者： Jianxing Liu xinyuan Zhu Zhangming Shen Yihui Zhang AML Department of Engineering MechanicsCenter for Flexible Electronics TechnologyTsinghua UniversityBeijing 100084China

Developments of soft network materials with rationally distributed wavy microstructures have enabled many promising applications in bio-integrated electronic devices,due to their abilities to reproduce precisely nonlinear mechanical properties of human tissues/*** practical applications,the soft network materials usually serve as the encapsulation layer and/or substrate of bio-integrated electronic devices,where deterministic holes can be utilized to accommodate hard chips,thereby increasing the filling ratio of the device ***,it is essential to understand how the hole-type imperfection affects the stretchability of soft network materialswith various geometric *** presents a systematic investigation of the imperfection sensitivity of mechanical properties in soft network materials consisting of horseshoe microstructures,through combined computational and experimental studies.A factor of imperfection insensitivity of stretchability is introduced to quantify the influence of hole imperfections,as compared to the case of perfect soft network *** factor is shown to have different dependences on the arc angle and normalized width of horseshoe microstructures for triangular network *** soft triangular and Kagome network materials,especially with the arc angle in the range of(30?,60?),are found to be much more imperfection insensitive than corresponding traditional lattice materials with straight ***,the soft honeycomb network materials are not as imperfection insensitive as traditional honeycomb lattice materials.

关键词： Imperfect network material Imperfection insensitivity Microstructure shape Lattice topology Stretchability

Interstitial fluid flow:simulation of mechanical environment of cells in the interosseous membrane

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Acta Mechanica Sinica 2011年第4期27卷 602-610页

作者： Wei Yao Guang-Hong Ding Department of mechanics and Engineering Science Fudan University Shanghai Research Center of Acupuncture 200433 Shanghai China

In vitro experiments have shown that subtle fluid flow environment plays a significant role in living biological tissues, while there is no in vivo practical dynamical measurement of the interstitial fluid flow velocity. On the basis of a new finding that capillaries and collagen fibrils in the interosseous membrane form a parallel array, we set up a porous media model simulating the flow field with FLUENT software, studied the shear stress on interstitial cells＇ surface due to the interstitial fluid flow, and analyzed the effect of flow on protein space distribution around the ceils. The numerical simulation results show that the parallel nature of capillaries could lead to directional interstitial fluid flow in the direction of capillaries. Interstitial fluid flow would induce shear stress on the membrane of interstitial cells, up to 30 Pa or so, which reaches or exceeds the threshold values of cells＇ biological response observed in vitro. Interstitial fluid flow would induce nonuniform spacial distribution of secretion protein of mast cells. Shear tress on cells could be affected by capillary parameters such as the distance between the adjacent capillaries, blood pressure and the permeability coefficient of capillary＇s wall. The interstitial pressure and the interstitial porosity could also affect the shear stress on cells. In conclusion, numerical simulation provides an effective way for in vivo dynamic interstitial velocity research, helps to set up the vivid subtle interstitial flow environment of cells, and is beneficial to understanding the physiological functions of interstitial fluid flow.

关键词： Interstitial fluid flow Porous media. Numericalsimulation - Acupoint Sheer stress

Emergent antisymmetric wrinkling patterns in films on ridged substrates

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Science China(Physics,mechanics & Astronomy) 2023年第11期66卷 179-187页

作者： Jiahui Zhang Yi Sun Linghui He Yong Ni CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei230026China

We report the formation of antisymmetric wrinkling patterns in films on ridged substrates induced by the buckling instability of the substrates via finite element simulations and *** simulated results reveal that the uniaxial compression along the ridge can trigger both the wrinkling instability of the film and the lateral buckling instability of the *** latter could change the wrinkles from a symmetric pattern to an antisymmetric pattern in a range of film-substrate modulus ratio and aspect ratio of the ridge profile,as validated by the experimental observations.A three-dimensional phase diagram with four buckling patterns,i.e.,sole ridge buckling pattern,antisymmetric wrinkling pattern with different wavelengths from ridge buckling,symmetric wrinkling pattern without ridge buckling,and antisymmetric wrinkling pattern with the same wavelength as ridge buckling,is built with respect to the uniaxial compression,modulus ratio,and aspect *** results not only elucidate how and when the interplay between the wrinkling instability and the ridge instability results in the formation of the antisymmetric wrinkling pattern but also offer a way to generate controllable complex wrinkling patterns.

关键词： wrinkling pattern buckling instability ridged film-substrate system antisymmetric wrinkles