采用全细胞膜片钳技术,观察和厚朴酚(honokiol,Hnk)对急性分离的小鼠背根神经节上河豚毒素敏感型(TTX-S)钠电流及其通道动力学的影响,探讨Hnk可能的镇痛机制及作用靶点。结果显示:和厚朴酚浓度依赖性地抑制TTX-S钠电流,30μmol/L和厚朴...采用全细胞膜片钳技术,观察和厚朴酚(honokiol,Hnk)对急性分离的小鼠背根神经节上河豚毒素敏感型(TTX-S)钠电流及其通道动力学的影响,探讨Hnk可能的镇痛机制及作用靶点。结果显示:和厚朴酚浓度依赖性地抑制TTX-S钠电流,30μmol/L和厚朴酚可以使稳态激活曲线向较正电压方向偏移达10.2 m V,通道失活后恢复时间明显延长,但对稳态失活动力学特征无明显的影响。展开更多
Objective To explore the feasibility for therapy of spinal cord injury （SCI） by genetic engineering neural stem cell （NSC） modified by lentiviral vector. Methods Following the construction of the genetic engineer...Objective To explore the feasibility for therapy of spinal cord injury （SCI） by genetic engineering neural stem cell （NSC） modified by lentiviral vector. Methods Following the construction of the genetic engineering NSC modified by lentivirus to secrete both neurotrophic factor-3 （NT-3） and green fluorescence protein （GFP）, hemisection of spinal cord at the level of T10 was performed in 56 adult Wistar rats that were randomly divided into 4 groups （ n = 14 ）, namely 3 therapeutic groups and 1 control group. The therapeutic groups were dealed with NSC, genetic engineering NSC, and concentrated lentiviral supematant which carries both GFP and NT-3, respectively. Then used fluorescence microscope to detect the transgenic expression in vitro and in vivo, migration of the grafted cells in vivo, and used the Basso, Beattie, and Bresnahan （BBB） open-field locomotor test to assess the recovery of function. Results The transplanted cells could survive for long time in vivo and migrate for long distance. The stable transgenie expression could be detected in vivo. The hindlimb function of the injured rats in 3 therapeutic groups, especially those dealed with genetic engineering NSC, improved obviously. Concision It is feasible to combine NSC with lentivirus for the repair of SCI. NSC modified by lentivirus to deliver NT-3, acting as a source of neurotrophic factors and function cell in vivo, has the potential to participate in spinal cord repair.展开更多
In this paper, a model of topology optimization with linear buckling constraints is established based on an independent and continuous mapping method to minimize the plate/shell structure weight. A composite exponenti...In this paper, a model of topology optimization with linear buckling constraints is established based on an independent and continuous mapping method to minimize the plate/shell structure weight. A composite exponential function（CEF） is selected as filtering functions for element weight, the element stiffness matrix and the element geometric stiffness matrix, which recognize the design variables, and to implement the changing process of design variables from“discrete” to “continuous” and back to “discrete”. The buckling constraints are approximated as explicit formulations based on the Taylor expansion and the filtering function. The optimization model is transformed to dual programming and solved by the dual sequence quadratic programming algorithm. Finally, three numerical examples with power function and CEF as filter function are analyzed and discussed to demonstrate the feasibility and efficiency of the proposed method.展开更多
A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement co...A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formulation is derived, using approximations of the displacement and weight given by first- and second-order Taylor expansions. The optimization problem is thereby transformed into a standard quadratic programming problem that can be solved using a sequential quadratic programming approach. The feasibility and effectiveness of the proposed multimaterial topology optimization method are demonstrated by determining the best load transfer path for four numerical examples. The results reveal that the topologically optimized configuration of the multimaterial structure varies with the material properties, load conditions, and constraint. Firstly, the weight of the optimized multimaterial structure is found to be lower than that composed of a single material. Secondly, under the precondition of a displacement constraint, the weight of the topologically optimized multimaterial structure decreases as the displacement constraint value is increased. Finally, the topologically optimized multimaterial structures differ depending on the elastic modulus of the materials. Besides, the established optimization formulation is more reliable and suitable for use in practical engineering applications with structural performance parameters as constraint.展开更多
The purpose of the present work is to study the buckling problem with plate/shell topology optimization of orthotropic material. A model of buckling topology optimization is established based on the independent, conti...The purpose of the present work is to study the buckling problem with plate/shell topology optimization of orthotropic material. A model of buckling topology optimization is established based on the independent, continuous, and mapping method, which considers structural mass as objective and buckling critical loads as constraints. Firstly, composite exponential function (CEF) and power function (PF) as filter functions are introduced to recognize the element mass, the element stiffness matrix, and the element geometric stiffness matrix. The filter functions of the orthotropic material stiffness are deduced. Then these filter functions are put into buckling topology optimization of a differential equation to analyze the design sensitivity. Furthermore, the buckling constraints are approximately expressed as explicit functions with respect to the design variables based on the first-order Taylor expansion. The objective function is standardized based on the second-order Taylor expansion. Therefore, the optimization model is translated into a quadratic program. Finally, the dual sequence quadratic programming (DSQP) algorithm and the global convergence method of moving asymptotes algorithm with two different filter functions (CEF and PF) are applied to solve the optimal model. Three numerical results show that DSQP&CEF has the best performance in the view of structural mass and discretion.展开更多
A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structur...A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structural strength in engineering applications.First,a topology optimization model is established for a lightweight structure with element stress as constraints.Second,the stress globalization method is adopted to convert local stress constraints into strain energy constraints,which overcomes the difficulties caused by local stress constraints,such as model establishment,sensitivity analysis,and massive solution calculations.Third,the sensitivity of the objective function and constraint function is analyzed,and the method of moving asymptotes is employed to solve the optimization model.In addition,the additive hyperelasticity technique is utilized to solve the numerical instability induced by structures undergoing large deformation.Numerical examples are given to validate the feasibility of the proposed method.The method provides a significant reference for geometrically nonlinear optimization design.展开更多
基金Project(2022NSFSC0193)supported by the Natural Science Foundation of Sichuan Province,ChinaProject(52104143)supported by the National Natural Science Foundation of China+2 种基金Project(GKZD010084)supported by the State Key Laboratory of Ocean Engineering(Shanghai Jiao Tong University),ChinaProject(MAETIC202201)supported by the Open Project Program of Shandong Marine Aerospace Equipment Technological Innovation Center,Ludong University,ChinaProject(GJJ2202702)supported by the Key Program of Department of Education of Jiangxi Province,China。
文摘采用全细胞膜片钳技术,观察和厚朴酚(honokiol,Hnk)对急性分离的小鼠背根神经节上河豚毒素敏感型(TTX-S)钠电流及其通道动力学的影响,探讨Hnk可能的镇痛机制及作用靶点。结果显示:和厚朴酚浓度依赖性地抑制TTX-S钠电流,30μmol/L和厚朴酚可以使稳态激活曲线向较正电压方向偏移达10.2 m V,通道失活后恢复时间明显延长,但对稳态失活动力学特征无明显的影响。
基金Supported by the Natural Science Foundation of Yunnan Province(2002C0070M).
文摘Objective To explore the feasibility for therapy of spinal cord injury （SCI） by genetic engineering neural stem cell （NSC） modified by lentiviral vector. Methods Following the construction of the genetic engineering NSC modified by lentivirus to secrete both neurotrophic factor-3 （NT-3） and green fluorescence protein （GFP）, hemisection of spinal cord at the level of T10 was performed in 56 adult Wistar rats that were randomly divided into 4 groups （ n = 14 ）, namely 3 therapeutic groups and 1 control group. The therapeutic groups were dealed with NSC, genetic engineering NSC, and concentrated lentiviral supematant which carries both GFP and NT-3, respectively. Then used fluorescence microscope to detect the transgenic expression in vitro and in vivo, migration of the grafted cells in vivo, and used the Basso, Beattie, and Bresnahan （BBB） open-field locomotor test to assess the recovery of function. Results The transplanted cells could survive for long time in vivo and migrate for long distance. The stable transgenie expression could be detected in vivo. The hindlimb function of the injured rats in 3 therapeutic groups, especially those dealed with genetic engineering NSC, improved obviously. Concision It is feasible to combine NSC with lentivirus for the repair of SCI. NSC modified by lentivirus to deliver NT-3, acting as a source of neurotrophic factors and function cell in vivo, has the potential to participate in spinal cord repair.
基金supported by the National Natural Science Foundation of China(Grants 11072009,111720131)
文摘In this paper, a model of topology optimization with linear buckling constraints is established based on an independent and continuous mapping method to minimize the plate/shell structure weight. A composite exponential function（CEF） is selected as filtering functions for element weight, the element stiffness matrix and the element geometric stiffness matrix, which recognize the design variables, and to implement the changing process of design variables from“discrete” to “continuous” and back to “discrete”. The buckling constraints are approximated as explicit formulations based on the Taylor expansion and the filtering function. The optimization model is transformed to dual programming and solved by the dual sequence quadratic programming algorithm. Finally, three numerical examples with power function and CEF as filter function are analyzed and discussed to demonstrate the feasibility and efficiency of the proposed method.
基金the National Natural Science Foundation of China (Grants 11072009 and 11872080)Beijing Education Committee Development Project (Grant SQKM201610005001).
文摘A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formulation is derived, using approximations of the displacement and weight given by first- and second-order Taylor expansions. The optimization problem is thereby transformed into a standard quadratic programming problem that can be solved using a sequential quadratic programming approach. The feasibility and effectiveness of the proposed multimaterial topology optimization method are demonstrated by determining the best load transfer path for four numerical examples. The results reveal that the topologically optimized configuration of the multimaterial structure varies with the material properties, load conditions, and constraint. Firstly, the weight of the optimized multimaterial structure is found to be lower than that composed of a single material. Secondly, under the precondition of a displacement constraint, the weight of the topologically optimized multimaterial structure decreases as the displacement constraint value is increased. Finally, the topologically optimized multimaterial structures differ depending on the elastic modulus of the materials. Besides, the established optimization formulation is more reliable and suitable for use in practical engineering applications with structural performance parameters as constraint.
基金supported by the National Natural Science Foundation of China (Grants 11072009, 11172013)the Beijing Education Committee Development Project (Grant SQKM2016100 05001)the Beijing University of Technology Basic Research Fund (Grant 001000514313003)
文摘The purpose of the present work is to study the buckling problem with plate/shell topology optimization of orthotropic material. A model of buckling topology optimization is established based on the independent, continuous, and mapping method, which considers structural mass as objective and buckling critical loads as constraints. Firstly, composite exponential function (CEF) and power function (PF) as filter functions are introduced to recognize the element mass, the element stiffness matrix, and the element geometric stiffness matrix. The filter functions of the orthotropic material stiffness are deduced. Then these filter functions are put into buckling topology optimization of a differential equation to analyze the design sensitivity. Furthermore, the buckling constraints are approximately expressed as explicit functions with respect to the design variables based on the first-order Taylor expansion. The objective function is standardized based on the second-order Taylor expansion. Therefore, the optimization model is translated into a quadratic program. Finally, the dual sequence quadratic programming (DSQP) algorithm and the global convergence method of moving asymptotes algorithm with two different filter functions (CEF and PF) are applied to solve the optimal model. Three numerical results show that DSQP&CEF has the best performance in the view of structural mass and discretion.
基金This work was supported by the National Natural Science Foundation of China(11872080)Beijing Natural Science Foundation(3192005)。
文摘A geometrically nonlinear topology optimization method for continuum structures is proposed based on the independent continuous mapping method.The stress constraint problem is studied due to the importance of structural strength in engineering applications.First,a topology optimization model is established for a lightweight structure with element stress as constraints.Second,the stress globalization method is adopted to convert local stress constraints into strain energy constraints,which overcomes the difficulties caused by local stress constraints,such as model establishment,sensitivity analysis,and massive solution calculations.Third,the sensitivity of the objective function and constraint function is analyzed,and the method of moving asymptotes is employed to solve the optimization model.In addition,the additive hyperelasticity technique is utilized to solve the numerical instability induced by structures undergoing large deformation.Numerical examples are given to validate the feasibility of the proposed method.The method provides a significant reference for geometrically nonlinear optimization design.
