目的:研究远隔缺血预适应(RIPC)对大鼠脑缺血模型的保护作用及分子机制。方法:30只成年雄性SD大鼠随机分为4组:假手术组(sham)、RIPC组、缺血再灌注组(MCAO/R)组、RIPC+MCAO/R组;术前通过夹闭双侧股动脉给予相应组RIPC处理,利用大脑中...目的:研究远隔缺血预适应(RIPC)对大鼠脑缺血模型的保护作用及分子机制。方法:30只成年雄性SD大鼠随机分为4组:假手术组(sham)、RIPC组、缺血再灌注组(MCAO/R)组、RIPC+MCAO/R组;术前通过夹闭双侧股动脉给予相应组RIPC处理,利用大脑中动脉栓塞再灌注法(MCAO/R)制备大鼠缺血性脑卒中模型,神经功能评分检测大鼠的神经功能,用2,3,5-三苯四唑氯(TTC)对脑切片进行染色以评估脑梗死的程度。利用real time RT-PCR检测大脑皮质中低氧诱导因子-1α(HIF-1α)和血管内皮生长因子(VEGF) mRNA的表达。结果:与MCAO/R组大鼠相比,RIPC处理组大鼠神经功能缺损症状较轻(P<0.05),脑梗死体积缩小(P<0.01),皮质中HIF-1α和VEGF mRNA的表达表达明显升高(P<0.05)。结论:RIPC处理对减轻缺血性脑卒中大鼠具有保护作用,其分子机制可能与激活HIF-1α/VEGF通路有关。展开更多
Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is o...Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is on London’s quantum mechanical potential which is an analytical expression valid until a certain characteristic distance where “attractive” molecular interactions change character and become “repulsive” and cannot be described by the classical form of London’s potential. It turns out that the suggested internal length gradient (ILG) generalization of London’s potential generates both an “attractive” and a “repulsive” branch, and by adjusting the corresponding gradient parameters, the behavior of the empirical Lennard-Jones potentials is theoretically captured.展开更多
Nanoindentation is a useful technique to measure material properties at microscopic level.However,the intrinsically multiscale nature makes it challenging for large-scale simulations to be carried out.It is shown that...Nanoindentation is a useful technique to measure material properties at microscopic level.However,the intrinsically multiscale nature makes it challenging for large-scale simulations to be carried out.It is shown that in molecular statics simulations of nanoindentation,the separated dislocation loops(SDLs)are trapped in simulation box which detrimentally affects the plastic behavior in the plastic zone(PZ);and the long-distance propagation of SDLs consumes much computational cost yet with little contribution to the variation of tip force.To tackle the problem,the dislocation loop erasing(DLE)method is proposed in the work to alleviate the influence of artificial boundary conditions on the SDL–PZ interaction and improve simulation efficiency.Simulation results indicate that the force–depth curves obtained from simulations with and without DLE are consistent with each other,while the method with DLE yields more reasonable results of microstructural evolution and shows better efficiency.The new method provides an alternative approach for large-scale molecular simulation of nanoindentation with reliable results and higher efficiency and also sheds lights on improving existing multiscale methods.展开更多
文摘目的:研究远隔缺血预适应(RIPC)对大鼠脑缺血模型的保护作用及分子机制。方法:30只成年雄性SD大鼠随机分为4组:假手术组(sham)、RIPC组、缺血再灌注组(MCAO/R)组、RIPC+MCAO/R组;术前通过夹闭双侧股动脉给予相应组RIPC处理,利用大脑中动脉栓塞再灌注法(MCAO/R)制备大鼠缺血性脑卒中模型,神经功能评分检测大鼠的神经功能,用2,3,5-三苯四唑氯(TTC)对脑切片进行染色以评估脑梗死的程度。利用real time RT-PCR检测大脑皮质中低氧诱导因子-1α(HIF-1α)和血管内皮生长因子(VEGF) mRNA的表达。结果:与MCAO/R组大鼠相比,RIPC处理组大鼠神经功能缺损症状较轻(P<0.05),脑梗死体积缩小(P<0.01),皮质中HIF-1α和VEGF mRNA的表达表达明显升高(P<0.05)。结论:RIPC处理对减轻缺血性脑卒中大鼠具有保护作用,其分子机制可能与激活HIF-1α/VEGF通路有关。
文摘Motivated by the special theory of gradient elasticity (GradEla), a proposal is advanced for extending it to construct gradient models for interatomic potentials, commonly used in atomistic simulations. Our focus is on London’s quantum mechanical potential which is an analytical expression valid until a certain characteristic distance where “attractive” molecular interactions change character and become “repulsive” and cannot be described by the classical form of London’s potential. It turns out that the suggested internal length gradient (ILG) generalization of London’s potential generates both an “attractive” and a “repulsive” branch, and by adjusting the corresponding gradient parameters, the behavior of the empirical Lennard-Jones potentials is theoretically captured.
基金Supports from the National Natural Science Foundation of China(Grant Nos.11790292,11672298,and 11432014)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB22040501)are gratefully acknowledged.Computations are performed on the ScGrid of Supercomputing Center,Computer Network Information Center of Chinese Academy of Sciences and LNMGrid of the State Key Laboratory of Nonlinear Mechanics.
文摘Nanoindentation is a useful technique to measure material properties at microscopic level.However,the intrinsically multiscale nature makes it challenging for large-scale simulations to be carried out.It is shown that in molecular statics simulations of nanoindentation,the separated dislocation loops(SDLs)are trapped in simulation box which detrimentally affects the plastic behavior in the plastic zone(PZ);and the long-distance propagation of SDLs consumes much computational cost yet with little contribution to the variation of tip force.To tackle the problem,the dislocation loop erasing(DLE)method is proposed in the work to alleviate the influence of artificial boundary conditions on the SDL–PZ interaction and improve simulation efficiency.Simulation results indicate that the force–depth curves obtained from simulations with and without DLE are consistent with each other,while the method with DLE yields more reasonable results of microstructural evolution and shows better efficiency.The new method provides an alternative approach for large-scale molecular simulation of nanoindentation with reliable results and higher efficiency and also sheds lights on improving existing multiscale methods.
