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IL-8-induced L-selectin shedding regulates its binding kinetics to PSGL-1

Chinese Science Bulletin 2009年第16期54卷 2786-2793页

作者： JIA XiaoLing1,2.3, CHEN Juan1,2.& LONG Mian1,2.1 National Microgravity Laboratory, institute of mechanics, Chinese Academy of Sciences, beijing 100190,{2. 2.center of biomechanics and bioengineering, institute of mechanics, Chinese Academy of Sciences, beijing 100190,{2. 3 School of Biological Science and Medical Engineering, Beihang University, beijing 100083,{2. National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China center of biomechanics and {2. Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China School of Biological Science and Medical Engineering Beihang University Beijing 100083 China

L-selectin plays a crucial role in inflammation cascade by initiating the tethering and rolling of leukocytes on endothelium wall. While many L-selectin molecules are rapidly shed from the cell surface upon activation, the remaining membrane-anchored L-selectin may still play an important role in regulating leukocyte rolling and adhesion with different binding kinetics. Here we developed an in vitro model to activate Jurkat cells via interlukin-8 (IL-8) and quantified the two-dimensional (2.) binding kinetics, using a micropipette aspiration assay, of membrane-anchored L-selectin to P-selectin glycoprotein ligand 1 (PSGL-1) ligand coupled onto human red blood cells (RBCs). The data indicated that L-selectin shedding reduced the amount of membrane-anchored L-selectin and lowered both its reverse and forward rates. These results suggested that the rolling dynamics of activated leukocytes was determined by two opposite impacts: reducing the surface presentation would enhance the rolling but lowering the kinetic rates would decrease the rolling. This finding provides a new insight into under-standing how L-selectin shedding regulates leukocyte rolling and adhesion.

关键词：结合动力学选择素配体白细胞介素8 Jurkat细胞诱导细胞表面微管吸吮

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Dynamics of morphological changes for mitochondrial fission and fusion

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Science china(Physics,mechanics & Astronomy) 2010年第4期53卷 680-689页

作者： WANG ShiQi 1,2.4 , FU ChangLiang 1,2., ZHANG Yan 1,2., CHEN Quan 3 & LONG Mian 1,2.1 Key Laboratory of Microgravity (National Microgravity Laboratory), beijing 100190, china {2., institute of mechanics, Chinese Academy of Sciences, beijing 100190, china 3 State Key Laboratory of Biomembrane and Membrane Biotechnology, institute of Zoology, Chinese Academy of Sciences, beijing 100101, china 4 institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, beijing 100044, china 1. Key Laboratory of Microgravity (National Microgravity Laboratory) Beijing 100190 China2. Center for Biomechanics and Bioengineering Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China4. Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China3. State Key Laboratory of Biomembrane and Membrane Biotechnology Institute of Zoology Chinese Academy of Sciences Beijing 100101 China

Mitochondria experience continuous fusion and fission in a living cell, but their dynamics remains poorly quantified. Here a theoretical model was developed, upon a simplified population balance equation (PBE), to predict the morphological changes induced by mitochondrial fission and fusion. Assuming that both fission and fusion events are statistically independent, the survival probability of mitochondria staying in the fission or fusion state was formulated as an exponentially-decayed function with time, which depended on the time-dependent distribution of the mitochondrial volume and the fission and fusion rates. Parametric analysis was done for two typical volume distributions. One was Gamma distribution and the other was Gaussian distribution, derived from the measurements of volume distribution for individual mitochondria in a living cell and purified mitochondria in vitro. The predictions indicated that the survival probability strongly depended on morphological changes of individual mitochondria and was inversely correlated to the fission and fusion rates. This work provided a new insight into quantifying the mitochondrial dynamics via monitoring the evolution of the mitochondrial volume.

关键词： mitochondria morphology fission fusion dynamics modeling

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Liquid propellant analogy technique in dynamic modeling of launch vehicle

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Science china(Technological Sciences) 2010年第8期53卷 2102-2110页

作者： PAN ZhongWen 1,2.,XING YuFeng 1 ,ZHU LiWen 2.,DONG Kai 2.&SUN Mu 2.1Solid mechanics Research center,{2. University of Aeronautics and Astronautics,{2. 100191,china 2.{2. Astronautics Systems Engineering institute,{2. 100076,china 1. Solid mechanics Research center Beijing University of Aeronautics and Astronautics Beijing 100191 China2. Beijing Astronautics Systems Engineering Institute Beijing 100076 China

The coupling effects among lateral mode,longitudinal mode and torsional mode of a launch vehicle cannot be taken into account in traditional dynamic analysis using lateral beam model and longitudinal spring-mass model *** deal with the problem,propellant analogy methods based on beam model are proposed and coupled mass-matrix of liquid propellant is constructed through additional mass in the present *** an integrated model of launch vehicle for free vibration analysis is established,by which research on the interactions between longitudinal and lateral modes,longitudinal and torsional modes of the launch vehicle can be *** examples for tandem tanks validate the present method and its necessity.

关键词： dynamic characteristics coupled mass integrative modeling propellant analogy

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Influence of processing temperature on microstructure and microhardness of copper subjected to high-pressure torsion

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Science china(Technological Sciences) 2010年第6期53卷 1534-1539页

作者： XIE ZiLing1,2.XIE JiJia2.HONG YouShi2.& WU XiaoLei2.1 College of Architecture and Civil Engineering,University of Wenzhou,Wenzhou 32.035,china 2.State Key Laboratory of Nonlinear mechanics,{2. of mechanics,Chinese Academy of Sciences,beijing 100190,china 1. College of Architecture and Civil Engineering University of Wenzhou Wenzhou 325035 China2. State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

Cu samples were subjected to high-pressure torsion (HPT) with up to 6 turns at room temperature (RT) and liquid nitrogen temperature (LNT),*** effects of temperature on grain refinement and microhardness variation were *** the samples after HPT processing at RT,the grain size reduced from 43 μm to 2.5 nm,and the Vickers microhardness increased from HV52.to ***,for the samples after HPT processing at LNT,the value of microhardness reached its maximum of HV150 near the center of the sample and it decreased to HV80 at the periphery *** observations revealed that HPT straining at LNT induced lamellar structures with thickness less than 100 nm appearing near the central region of the sample,but further deformation induced an inhomogeneous distribution of grain sizes,with submicrometer-sized grains embedded inside micrometer-sized *** submicrometer-sized grains with high dislocation density indicated their nonequilibrium *** the contrary,the micrometer-sized grains were nearly free of dislocation,without obvious deformation trace remaining in *** images demonstrated that the appearance of micrometer-sized grains is the result of abnormal grain growth of the deformed fine grains.

关键词： copper high pressure torsion (HPT) microstructure grain size microhardness cryogenic temperature

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Numerical simulations of leading-edge vortex core axial velocity for flow over delta wings

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Science china(Technological Sciences) 2009年第7期52卷 2029-2036页

作者： CHEN Lan1, 2.& WANG JinJun1 1 institute of Fluid mechanics, {2. University of Aeronautics and Astronautics, {2. 100191, china 2.4} Aerodynamic Research and Development center (CARDC), Mianyang 62.000, china 1. institute of Fluid mechanics Beijing University of Aeronautics and Astronautics Beijing 100191 China 2. china Aerodynamic Research and Development center (CARDC) Mianyang 621000 China

Numerical simulations have been performed to investigate the characteristics of leading-edge vortex core axial velocity over two delta wings with leading edge swept angles Λ =50°and 76°, respectively. It is obtained that Reynolds number has the most important effect on the axial velocity of the primary leading-edge vortex core. At Reynolds numbers larger than 105, the jet-like flow of the vortex core is the most common type for both the large and the moderate swept delta wings. While if Reynolds number decreases to 103―104, the core axial velocity distributions for these two delta wings present the wake-like profile for all angles of attack considered in the present investigation.

关键词： delta wing low Reynolds number vortex flows

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Gas kinetic algorithm for flows in Poiseuille-like microchannels using Boltzmann model equation

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Science china(Physics,mechanics & Astronomy) 2005年第4期48卷 496-512页

作者： LI Zhihui1,2. ZHANG Hanxin1 & FU Song2.⒈ National Laboratory for CFD, Hypervelocity Aerodynamics institute,china Aerodynamics Research and Development {2.,Mianyang 62.000,china 2.Department of Engineering mechanics,Tsinghua University,beijing 100084,china 1. National Laboratory for CFD Hypervelocity Aerodynamics Institute China Aerodynamics Research and Development Center 621000 Mianyang China 2. Department of Engineering mechanics Tsinghua University 100084 Beijing China

The gas-kinetic unified algorithm using Boltzmann model equation have been extended and developed to solve the micro-scale gas flows in Poiseuille-like micro-channels from Micro-Electro-Mechanical Systems (MEMS). The numerical modeling of the gas kinetic boundary conditions suitable for micro-scale gas flows is presented. To test the present method, the classical Couette flows with various Knudsen numbers, the gas flows from short microchannels like plane Poiseuille and the pressure-driven gas flows in two-dimensional short microchannels have been simulated and compared with the approximate solutions of the Boltzmann equation, the related DSMC results, the modified N-S solutions with slip-flow boundary theory, the gas-kinetic BGK-Burnett solutions and the experimental data. The comparisons show that the present gas-kinetic numerical algorithm using the mesoscopic Boltzmann simplified velocity distribution function equation can effectively simulate and reveal the gas flows in microchannels. The numerical experience indicates that this method may be a powerful tool in the numerical simulation of micro-scale gas flows from MEMS.

关键词： Boltzmann model equation, discrete velocity ordinate method, finite-difference scheme, Couette flow, Poiseuille flow, gas flow in short-microchannel.

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Experimental EOS determination of aluminum at Mbar pressure

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Science china(Physics,mechanics & Astronomy) 2004年第4期47卷 416-423页

作者： CHEN Jianping1,2. LI Ruxin1, ZENG Zhinan1, WANG Xingtao1 & XU Zhizhan1 1. Shanghai institute of Optics and Fine mechanics, Shanghai 2.1800,{2. 2. beijing Aeronautical Technology Research center, beijing 100076,{2. 1. Shanghai institute of Optics and Fine mechanics 201800 Shanghai China 2. beijing Aeronautical Technology Research center 100076 Beijing China

A shock wave is driven by a laser pulse of 1.2.ps duration (FWHM), with the intensity of ～1014 W/cm2.at 785 nm, irradiating a 500 nm thick aluminum foil. A chirped laser pulse split from the main pulse is used to detect the shock breakout process at the rear surface of the target based on frequency domain interferometry. The mean shock velocity determination benefits from the precise synchronization (＜100fs resolution) of the shock pump and probe laser pulses, which is calculated from the time the shock takes to travel the 500 nm thick aluminum. The released particle velocity determination benefits from the chirped pulse frequency domain interferometry. The average shock velocity is 15.15 km/s and the shock release particle velocity is 15.2. km/s, and the corresponding pressure after shock is 3.12.Mbar under our experimental condition.

关键词： shock wave, equation of state, chirped laser pulse.

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Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(2..5) bulk metallic glass up to 2. GPa

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Science china(Physics,mechanics & Astronomy) 2005年第3期48卷 319-324页

作者： LI Gong 1, 2., ZHAN Zaiji 2., LIU Jing 3 , YUN Jinku 1 , SUN Liling 2., LIU Riping 1 , ZHANG Jun 2.& WANG Wenkui 1, 2.1. Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, china 2. center for Condensed Matter Physics, {2. of Physics, Chinese Academy of Sciences, beijing 100080, china 3. BSRF, {2. of High Energy Physics, Chinese Academy of Sciences, beijing 100039, china 1. Key Laboratory of Metastable Materials Science and Technology Yanshan University 066004 Qinhuangdao China 2. center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 3. BSRF Institute of High Energy Physics Chinese Academy of Sciences 100039 Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be2..5 bulk metallic glass (BMG) is investigated at room temperature up to 2. GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

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Developing a microfluidic-based system to quantify cell capture efficiency

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Science china(Life Sciences) 2009年第2期52卷 173-181页

作者： YANG Fan, GAO YuXin, ZHANG Yan, CHEN Juan & LONG Mian National Microgravity Laboratory and center for biomechanics and {2., institute of mechanics, Chinese Academy of Sciences, beijing 100080, china 1. National Microgravity Laboratory and center for biomechanics and {2. Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Micro-fabrication technology has substantial potential for identifying molecular markers expressed on the surfaces of tissue cells and viruses. It has been found in several conceptual prototypes that cells with such markers are able to be captured by their antibodies immobilized on microchannel substrates and unbound cells are flushed out by a driven flow. The feasibility and reliability of such a microflu- idic-based assay, however, remains to be further tested. In the current work, we developed a microflu- idic-based system consisting of a microfluidic chip, an image grabbing unit, data acquisition and analysis software, as well as a supporting base. Specific binding of CD59-expressed or BSA-coupled human red blood cells (RBCs) to anti-CD59 or anti-BSA antibody-immobilized chip surfaces was quan- tified by capture efficiency and by the fraction of bound cells. Impacts of respective flow rate, cell concentration, antibody concentration and site density were tested systematically. The measured data indicated that the assay was robust. The robustness was further confirmed by capture efficiencies measured from an independent ELISA-based cell binding assay. These results demonstrated that the system developed provided a new platform to effectively quantify cellular surface markers effectively, which promoted the potential applications in both biological studies and clinical diagnoses.

关键词： cell surface marker microfluidic capture efficiency

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Observation results of relativistic electrons detected by Fengyun-1 satellite and analysis of relativistic electron enhancement (REE) events

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Science china(Physics,mechanics & Astronomy) 2008年第12期51卷 1947-1956页

作者： YANG XiaoChao1,2. & WANG ShiJin1 1 center for Space Science and Applied Research, Chinese Academy of Sciences, beijing 100190,{2. 2.Graduate University of Chinese Academy of Sciences, beijing 100049,{2. 1. center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100190 China 2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

The space particle component detector on Fengyun-1 satellite which works at the sun-synchronous orbit of about 870 km altitude has detected relativistic electrons for a long time. In comparison with the SAMPEX satellite observations during 1999–2.04, the relativistic electron data from Fengyun-1 satellite from June 1999 to 2.05 are used to analyze the relativistic electron enhancement (REE) events at the low earth orbit, and the possible correlation among REE events at the low earth orbit, high-speed solar wind and geomagnetic storms is discussed. The statistical result presents that 45 REE events are found in total during this time period, and the strong REE events with the maximum daily average flux > 400 cm?2.srt-1·s?1 occur mostly during the transition period from solar maximum to solar minimum. Among these 45 REE events, four strong REE events last a longer time period from 2.-to 51-day and correlate closely with high speed solar wind and strong geomagnetic storms. Meanwhile, several strong geomagnetic storms occur continuously before these REE events, and these continuous geomagnetic storms would be an important factor causing these long-lasting strong REE events. The correlation analysis for overall 45 events indicates that the strength of the REE events correlates with the solar wind speed and the strength of the geomagnetic storm, and the correlation for strong REE events is much stronger than that for weak REE events.

关键词： relativistic electron enhancement low earth orbit high-speed solar wind geomagnetic storm

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