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A mathematical model of cortical bone remodeling at cellular level under mechanical stimulus

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Acta Mechanica Sinica 2012年第6期28卷 1678-1692页

作者： qing-hua qin Ya-Nan Wang Research School of Engineering The Australian National University

A bone cell population dynamics model for cor- tical bone remodeling under mechanical stimulus is devel- oped in this paper. The external experiments extracted from the literature which have not been used in the creation of the model are used to test the validity of the model. Not only can the model compare reasonably well with these ex- perimental results such as the increase percentage of final values of bone mineral content （BMC） and bone fracture en- ergy （BFE） among different loading schemes （which proves the validity of the model）, but also predict the realtime devel- opment pattern of BMC and BFE, as well as the dynamics of osteoblasts （OBA）, osteoclasts （OCA）, nitric oxide （NO） and prostaglandin E2 （PGE2） for each loading scheme, which can hardly be monitored through experiment. In conclusion, the model is the first of its kind that is able to provide an in- sight into the quantitative mechanism of bone remodeling at cellular level by which bone cells are activated by mechan- ical stimulus in order to start resorption/formation of bone mass. More importantly, this model has laid a solid foun- dation based on which future work such as systemic control theory analysis of bone remodeling under mechanical stimu- lus can be investigated. The to-be identified control mecha- nism will help to develop effective drugs and combined non- pharmacological therapies to combat bone loss pathologies. Also this deeper understanding of how mechanical forces quantitatively interact with skeletal tissue is essential for the generation of bone tissue for tissue replacement purposes in tissue engineering.

关键词： Cortical bone remodeling Cell population dy-namics Mechanotransduction Mechanosensitivity Bonefracture energy - Bone mineral content

HYBRID FEM WITH FUNDAMENTAL SOLUTIONS AS TRIAL FUNCTIONS FOR HEAT CONDUCTION SIMULATION

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Acta Mechanica Solida Sinica 2009年第5期22卷 487-498页

作者： Hui Wang qing-hua qin College of Civil Engineering and Architecture Henan University of Technologyl Zhengzhou 450052 China Department of Engineering Australian National University Canberra ACT 0200 Australia

A new type of hybrid finite element formulation with fundamental solutions as internal interpolation functions, named as HFS-FEM, is presented in this paper and used for solving two dimensional heat conduction problems in single and multi-layer materials. In the proposed approach, a new variational functional is firstly constructed for the proposed HFS-FE model and the related existence of extremum is presented. Then, the assumed internal potential field constructed by the linear combination of fundamental solutions at points outside the elemental domain under consideration is used as the internal interpolation function, which analytically satisfies the governing equation within each element. As a result, the domain integrals in the variational functional formulation can be converted into the boundary integrals which can significantly simplify the calculation of the element stiffness matrix. The independent frame field is also introduced to guarantee the inter-element continuity and the stationary condition of the new variational functional is used to obtain the final stiffness equations. The proposed method inherits the advantages of the hybrid Trefftz finite element method （HT-FEM） over the conventional finite element method （FEM） and boundary element method （BEM）, and avoids the difficulty in selecting appropriate terms of T-complete functions used in HT-FEM, as the fundamental solutions contain usually one term only, rather than a series containing infinitely many terms. Further, the fundamental solutions of a problem are, in general, easier to derive than the T-complete functions of that problem. Finally, several examples are presented to assess the performance of the proposed method, and the obtained numerical results show good numerical accuracy and remarkable insensitivity to mesh distortion.

关键词： hybrid FEM fundamental solution variational functional heat conduction

Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

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Acta Mechanica Sinica 2010年第1期26卷 37-44页

作者： YananWang qing-hua qin Department of Engineering Australian National UniversityCanberra ACT 0200 Australia

The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.

关键词： Control mechanism Parametric study Mechanical bone remodeling

Modeling and Control for Magnetostrictive Hysteresis

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Chinese Journal of Aeronautics 2006年第B12期19卷 146-150页

作者： MAO Jian-qin MAYan-hua The Seventh Research Division Beijing University of Aeronautics and Astronautics Beijing 100083 China

To deal with the rate-dependent hysteresis presented in a magnetostrictive actuator, a new method of modeling and control is proposed. The relationship between inputs and outputs of the actuator is approximately described by a dynamic differential equation with two rate-dependent coefficients, each expressed as a polynomial of frequency. For a given frequency, the coefficients will be able to be estimated by approximating the experimental data of the outputs of the magnetostrictive actuator. Based on this model, a quasi-PID controller is designed. In the space of the coefficients and frequency, the stable domain of closed loop system with hysteresis is analyzed. The numerical simulation and experiments have born witness to the feasibility of the proposed new method.

关键词： mechatronics engineering quasi-PID controller modeling magnetostrictive hysteresis

Chemical modulation of cell fates： in situ regeneration

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Science China(Life Sciences) 2018年第10期61卷 1137-1150页

作者： hua qin Andong Zhao Xiaobing Fu Graduate School of Tianjin Medical University Tianjin 300070China Cell Biology and Tissue Repair Laboratory Key Laboratory of Wound Repair and Regeneration of PLA the First Hospital Affiliated to the PLA General HospitalBeijing 100048 China College of Life Sciences PLA General Hospital PLA Medical CollegeBeijing 100853 China

Chemical modulation of cell fates has been widely used to promote tissue and organ regeneration. Small molecules can target the self-renewal, expansion, differentiation, and survival of endogenous stem cells for enhancing their regenerative power or induce dedifferentiation or transdifferentiation of mature cells into proliferative progenitors or specialized cell types needed for regeneration. Here, we discuss current progress and potential using small molecules to promote in vivo regenerative processes by regulating the cell fate. Current studies of small molecules in regeneration will provide insights into developing safe and efficient chemical approaches for in situ tissue repair and regeneration.

关键词： small molecule in situ regeneration adult stem cells somatic cells dedifferentiation transdifferentiation reprogramming

Syntheses and Crystal Structures of Co(Ⅱ)Complexes with 5-Tert-butyl Isophthalic Acid

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Chinese Journal of Structural Chemistry 2010年第7期29卷 1108-1114页

作者： qin Jian-hua JU Feng-Yang College of Chemistry and Chemical Engineering Luoyang Normal University Luoyang 471022 China

Two new Co（ Ⅱ） coordination polymers {[Co（Htbip）2（H2O）4]·（H2O）}n 1 and {[Co2（tbip）2Copa）1.5]（H2tbip）}n 2 （H2tbip = 5-tert-butyl isophtha]ic acid, bpa = 1,2-dis（4-pyri- dyl）ethane） have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy and X-ray diffraction. Compound 1 exhibits a water-bridged 1-D linear chain which is extended by hydrogen bonds into a 3D supramolecular network, while compound 2 has a dinuclear unit extended by bpa ligand to form a 2-D layer.

关键词： Co(Ⅱ) complex 5-tert-butyl isophthalic acid crystal structure

Hybrid graded element model for transient heat conduction in functionally graded materials

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Acta Mechanica Sinica 2012年第1期28卷 128-139页

作者： Lei-Lei Cao qing-hua qin Ning Zhao Key Laboratory for Road Construction Technology＆ Equipment of MOE Chang＇ an University 710064 Xi＇ an China Research School of Engineering Australian National UniversityCanberra ACT 0200 Australia School of Mechatronics Northwestern Polytechnical University710072 Xi＇an China

This paper presents a hybrid graded element model for the transient heat conduction problem in functionally graded materials （FGMs）. First, a Laplace transform approach is used to handle the time variable. Then, a fundamental solution in Laplace space for FGMs is constructed. Next, a hybrid graded element is formulated based on the obtained fundamental solution and a frame field. As a result, the graded properties of FGMs are naturally reflected by using the fundamental solution to interpolate the intra-element field. Further, Stefest＇s algorithm is employed to convert the results in Laplace space back into the time-space domain. Finally, the performance of the proposed method is assessed by several benchmark examples. The results demonstrate well the efficiency and accuracy of the proposed method.

关键词： Graded element model Functionally graded materials Hybrid FEM Transient heat conduction

Environmental Effects on Rural-to-Urban Migration in China

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Chinese Journal of Population,Resources and Environment 2012年第3期10卷 9-17页

作者： qin hua Department of Environmental Studies University of Illinois at Springfield Springfield IL 62703 the United States

Abstract： Migration process has become increasingly important in recent research on population and the environment. A majority of the existing migration and environment literature has focused on the environmental causes and determinants of migration. With the largest rural-to-urban migration flow in world history, and growing concerns about the environmental problems accompanying its fast economic development, China provides a particularly important case for migration and environment research. This paper reviews major migration theories and recent research on environmental effects on migration, with specific attention to the influences of en- vironmental factors on rural-to-urban labor migration in China. A comprehensive multilevel conceptual framework is developed for studying the environmental causes of rural-to-urban migration in China. The effects of land resources on household labor migration decisions in rural China are explored to illustrate the application of this framework.

关键词： migration and environment environmental influ-ences multilevel conceptual framework land resources householdmigration decisions

Fermion Determinant with Dynamical Chiral Symmetry Breaking

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Communications in Theoretical Physics 2002年第8期38卷 185-188页

作者： LU qin YANG hua WANG qing Department of Physics Tsinghua University Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China Institute of Electronic Technology Information Engineering University Zhengzhou 450004 China Department of Physics Tsinghua University Beijing 100084 China Institute of Theoretical Physics Academia Sinica Beijing 100080 China

One-loop fermion determinant is discussed for the case in which the dynamical chiral symmetry breakingcaused by momentum-dependent fermion self-energy ∑(p2) takes place. The obtained series generalizes the heat kerne... 详细信息

关键词： determinant, dynamical symmetry breaking, heat kernel