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Modeling biomembranes and red blood cells by coarse-grained particle methods

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Applied Mathematics and Mechanics(English Edition) 2018年第1期39卷 3-20页

作者： h.LI h.Y.chang J.YANG L.LU Y.h.TANG G.LYKOTRAFITIS Division of Applied Mathematics Brown University Department of Materials Science and Engineering Massachusetts Institute of Technology Department of Mechanical Engineering University of Connecticut

In this work, the previously developed coarse-grained （CG） particle models for biomembranes and red blood cells （RBCs） are reviewed, and the advantages of the CG particle methods over the continuum and atomistic simulations for modeling biological phenomena are discussed. CG particle models can largely increase the length scale and time scale of atomistic simulations by eliminating the fast degrees of freedom while preserving the mesoscopic structures and properties of the simulated system. Moreover, CG particle models can be used to capture the microstructural alternations in diseased RBCs and simulate the topological changes of biomembranes and RBCs, which are the major challenges to the typical continuum representations of membranes and RBCs. The power and versatility of CG particle methods are demonstrated：through simulating the dynamical processes mvolving significant topological .changes e.g. lipid self-assembly vesicle fusion and membrane budding.

关键词： coarse-grained molecular dynamics,lipid bilayer red blood cell membrane membrane fusion

Circulation in the western tropical Pacific Ocean and its seasonal variation

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Chinese Science Bulletin 2002年第7期47卷 591-595,618页

作者： Wang Fan chang Ping hu Dunxin h.Seidel Institute of Oceanology Chinese Academy of Sciences266071QingdaoChina Department of Oceanography Texas A&M UniversityCollege Station77843TexasUSA

An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140°E and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference. The NECC transport also has a semi-annual fluctuation resulting from the phase lag between seasonal cycles of two tropical gyres’ recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughflow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon’s impact on it.

关键词： seasonal circulations equatorial currents low-latitude western boundary currents western tropical Pacific Ocean assimi-lation data.

h_∞ drift control of time-delayed seismic structures

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Earthquake Engineering and Engineering Vibration 2009年第4期8卷 617-626页

作者： chang-Ching chang Department of Civil Engineering Chung Hsing University(NCHU)

In this paper, an optimal h∞ control algorithm was applied to the design of an active tendon system installed at the first story of a multi-story building to reduce its interstory drift due to earthquake excitations. To achieve optimal control performance and to guarantee the stability of the control system, an optimum strategy to select control parameters γ and α was developed. Analytical expressions of the upper and the lower bounds of γ and α were obtained for a single degree-of-freedom system with state feedback control. The selection ranges for both γ and α are graphically defined so that the controlled system is always stable and the control performance is better than by the conventional LQR control algorithm. Numerical results from a controlled three-story building under real earthquake excitations demonstrate that the peak first interstory drift can be significantly reduced with maximum control force around 10% of the building weight. An optimum design flow chart was provided. In addition, for a time-delayed structure, this study gave explicit formulae to calculate the critical values of γ and a. The system stability and control performance can thus be guaranteed even with time delay.

关键词： h∞ control time delay stability analysis active control active tendon system: state feedback control

Tri-directional shaking table tests of vibration sensitive equipment with static dynamics interchangeable-ball pendulum system

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Earthquake Engineering and Engineering Vibration 2010年第1期9卷 103-112页

作者： C.S. Tsai Yung-chang Lin Wen-Shin Chen h.C. Su D G epartment of Civil Engineering Feng Chia University Taichung Chinese Taipei Graduate Institute of Civil and hydraulic Engineering Feng Chia University Taichung Chinese Taipei Department of Water Resources Engineering and Conservation Feng Chia University Taichung Chinese Taipei

Recently, the high-tech industry has become a key industry for economic development in many countries. however, vibration sensitive equipment located in these industrial buildings is vulnerable during earthquakes, which may cause huge economic loss. In this study, an innovative isolator for safeguarding the vibration sensitive equipment, namely, the static dynamics interchangeable^all pendulum system （SDI-BPS） is proposed and investigated to examine its protective capability for the vibration sensitive equipment during earthquakes through a series of tri-directional shaking table tests. The experimental results illustrate that the SDI-BPS isolator can provide significant damping to rolling types of base isolation systems for reducing the bearing displacement and size, and avoid the stress concentration, which can cause damage or scratches on the rolling surface of the isolator, to prolong its life span of service. The SDI-BPS isolator also provides excellent capability in protecting the vibration sensitive equipment and exhibits a stable behavior under long terms of service loadings and earthquakes.

关键词： ball pendulum system critical equipment base isolation vibration sensitive equipment base isolator passive control earthquake engineering structural control

RESEARCh OF ThE FEEDING SPEED ADOPTING CORED-WIRE METhOD TO SPhEROIDIZE DUCTILE IRON MELT

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Acta Metallurgica Sinica(English Letters) 2008年第5期21卷 362-368页

作者： G.W. chang h.X. Wang X.D. Yue h.L. Zhang School of Materials and Chemical Engineering Liaoning University of Technology Jinzhou 121001 China Mechanical and Electronic Engineering Department West Anhui University Liu＇an 237012 China Baotou Wen Xin Industry Limited Company Baotou 014000 China Manuscript received 29 August 2007

For settling the question of feeding speed in applying the cored-wire method to spheroidize ductile iron melt, ANSYS software was applied to simulate the heat transfer and mass transfer, and the melt time of the steel strip in the iron melt was determined by linking the heat transfer and mass transfer, and then the feeding speed was calcufated. Conclusions have been drawn that the iron layer was formed on the surface of the cored-wire during the wire-feeding process. The thickness is 0.073 mm when the temperature of the iron melt is 1500℃, the time from formation to remelting of the iron layer is 0.063 s. When the temperature of the iron melt is below 1500℃, the time taken for the steel strip to melt is rapidly shortened. When the temperature of the iron melt is above 1500℃, the variation amplitude of the steel strip melt change with time is gradually diminished. The melt time of the steel strip is rapidly increased with the increase of the steel strip thickness. When the temperature of the iron melt is 1500℃ and the carbon content is 4%, the melt time of a steel strip, which has a thickness of 0.5 mm, is thrice that of a steel strip whose thickness is 0.3 mm. The calculation results of the feeding speed are basically in agreement with the applied feeding speed in the factory.

关键词： Ductile iron Spheroidize Feeding speed Numerical simulation

ThE FINITE ELEMENT ANALYSIS OF ThE CONTROLLED-SOURCE ELECTROMAGNETIC INDUCTIONPROBLEMS BY FRACTIONAL-STEP PROJECTION METhOD

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Journal of Computational Mathematics 2004年第4期22卷 557-566页

作者： chang-fengMa DepartmentofMathematics HuazhongUniversityofScienceandTechnologyWuhan430074China

This paper provides an convergence analysis of a fractional-step projection method for the controlled-source electromagnetic induction problems in heterogenous electrically conducting media by means of finite element approximations. Error estimates in finite time are given. And it is verified that provided the time step τ is sufficiently small, the proposed algorithm yields for finite time T an error of O(h^s + τ) in the L^2-norm for the magnetic field h, where h is the mesh size and 1/2 < s <_ 1.

关键词： Controlled-source electromagnetic induction problems Fractional-step projection method Finite element Error analysis

Enhanced subacute ischemic stroke treatment via multistage drug delivery system design for combination therapy

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Science China Chemistry 2025年

作者： Xihan Xu Juan-Juan Li Jiamin Li hui-Yan Zhang Yilin Qi Bing-Sen Shi Tianqi Li Shan-Shan Su Weitao Zhao chang Chen Zhongying Gong huiyu Liu Ke-Rang Wang Dong-Sheng Guo Xue Xue State Key Laboratory of Medicinal Chemical Biology College of Pharmacy Nankai University College of Chemistry State Key Laboratory of Elemento-Organic Chemistry Key Laboratory of Functional Polymer Materials (Ministry of Education) Frontiers Science Center for New Organic Matter Collaborative Innovation Center of Chemical Science and EngineeringNankai University College of Chemistry and Materials Science State Key Laboratory of New Pharmaceutical Preparations and Excipients Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Ministry of Education) Key Laboratory of Chemical Biology of Hebei Province Hebei Research Center of the Basic Discipline of Synthetic Chemistry Hebei University Department of Neurology Tianjin First Central Hospital School of Medicine Nankai University Beijing Advanced Innovation Center for Soft Matter Science and Engineering State Key Laboratory of Organic-Inorganic Composites Beijing Laboratory of Biomedical Materials Bionanomaterials & Translational Engineering Laboratory Beijing Key Laboratory of BioprocessBeijing University of Chemical Technology

The management of acute ischemic stroke remains challenging due to its abrupt onset and the narrow treatment window,resulting in high rates of disability and *** therapy for neuroprotection and neurorepair strategies provided new hopes for subacute stroke *** we designed a multistage nanodelivery system that matches the unique microenvironment of the subacute phase of stroke,which utilizes calixarene as a building block to effectively load the neuroprotective drug *** calixarene is designed with glycosidic linkages targeting the glucose transporter 1 (GLUT1)on the blood-brain barrier (BBB) and azo bonds that are responsive to hypoxic ***,the decomposed calixarene molecules themselves possess intrinsic bio-activation to modulate inflammatory responses,achieving a multistage therapeutic approach that transitions from targeting to release and finally to *** approach combines anti-inflammation and neuroprotection,providing a multi-level treatment *** system was validated in a rat model of permanent middle cerebral artery occlusion (pMCAO),demonstrating that intravenous administration of the nanodelivery system repairs brain damage and improves motor function 24 h post-pMCAO *** work offers a precise and integrative strategy for stroke patients missing the acute therapy window to improve functional recovery and enhance the effect of comprehensive treatment.

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Modelling the dead fuel moisture content in a grassland of Ergun City,China

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Journal of Arid Land 2023年第6期15卷 710-723页

作者： chang chang chang Yu GUO Meng hU Yuanman CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China School of Geographical Sciences Northeast Normal UniversityChangchun 130024China E'erguna Wetland Ecosystem National Research Station Hulunbuir 022250China

The dead fuel moisture content(DFMC)is the key driver leading to fire *** estimating the DFMC could help identify locations facing fire risks,prioritise areas for fire monitoring,and facilitate timely deployment of fire-suppression *** this study,the DFMC and environmental variables,including air temperature,relative humidity,wind speed,solar radiation,rainfall,atmospheric pressure,soil temperature,and soil humidity,were simultaneously measured in a grassland of Ergun City,Inner Mongolia Autonomous Region of China in *** chose three regression models,i.e.,random forest(RF)model,extreme gradient boosting(XGB)model,and boosted regression tree(BRT)model,to model the seasonal DFMC according to the data *** ensure accuracy,we added time-lag variables of 3 d to the *** results showed that the RF model had the best fitting effect with an R2value of 0.847 and a prediction accuracy with a mean absolute error score of 4.764%among the three *** accuracies of the models in spring and autumn were higher than those in the other two *** addition,different seasons had different key influencing factors,and the degree of influence of these factors on the DFMC changed with time ***,time-lag variables within 44 h clearly improved the fitting effect and prediction accuracy,indicating that environmental conditions within approximately 48 h greatly influence the *** study highlights the importance of considering 48 h time-lagged variables when predicting the DFMC of grassland fuels and mapping grassland fire risks based on the DFMC to help locate high-priority areas for grassland fire monitoring and prevention.

关键词： dead fuel moisture content(DFMC) random forest(RF)model extreme gradient boosting(XGB)model boosted regression tree(BRT)model grassland Ergun City

Gravitational Field Excitation from the First Term of Quantum Wilson Loop

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Communications in Theoretical Physics 2006年第1X期46卷 77-86页

作者： ShAO Liang ShAO Dan ShAO chang-Gui h. Noda ChEN Yi-han Department of Applied Physics Wuhan University of Science and Technology Wuhan 430081 China Department of Physics Jianghan University Wuhan 430056 China Institute of Theoretical Physics Hubei University Wuhan 430062 China Department of Mathematical Sciences Ibaraki University Mito 310-8512 Japan

In 4-dimensional R-gravity, using the linear and square terms of the expanding expression of the space-time connection, we calculate the possible curvature excitation （order k^4） of gravitational field, which is given by the first term of quantum Wilson loop （w） through two-point Green＇s function of the connection. At the same time using the tree diagram propagators of gravitons, the lowest order （k^4） correction to （w） is also calculated through the graviton self-energy in the term. Under the accuracy condition up to order k^4, we have obtained a complete expression of the excitation contributed from the leading term （w^（2））of （w）.

关键词： excitation of gravitational field graviton self-energy correction complete expression of excitation of order k^4 in (w^(2))