TAR DNA结合蛋白43(transactive response DNA binding protein 43,TDP-43),一种可变剪切因子,可以特异性地结合富含TG序列的DNA,涉及多种神经退行性疾病.分子动力学模拟方法虽然是研究分子间相互作用强有力的工具,但它非常耗时,且难以...TAR DNA结合蛋白43(transactive response DNA binding protein 43,TDP-43),一种可变剪切因子,可以特异性地结合富含TG序列的DNA,涉及多种神经退行性疾病.分子动力学模拟方法虽然是研究分子间相互作用强有力的工具,但它非常耗时,且难以对有大的构象变化的体系进行充分采样来研究其变构行为.本工作使用粗粒化的基于弹性势的高斯网络模型(Gaussian network model,GNM)研究人TDP-43与靶标DNA间相互作用的动力学.进一步地,利用本课题组之前提出的基于GNM的热力学循环方法识别TDP-43与DNA相互作用的关键残基,其微扰引起了大的结合自由能的变化.DNA结合后,TDP-43上富含正电残基的loop1和loop3片段有较大的柔性损失,这反映了它们在识别和结合中的诱导契合作用.另外发现,基于热力学循环的方法不仅识别到一些与DNA特异性相互作用有关的重要残基,而且识别到一些远离结合界面但在结合引起的分子构象变化中发挥重要作用的残基.本研究有助于理解TDP-43与DNA的特异性相互作用,可为药物设计提供重要信息,另外该方法可以很方便地拓展到其他蛋白质-核酸相互作用动力学的研究.展开更多
Based on the working principle and the damping characteristic of hydraulic shock absorber, a fluid structure interaction method was presented, which was used to analyze the microcosmic and high-frequency processing me...Based on the working principle and the damping characteristic of hydraulic shock absorber, a fluid structure interaction method was presented, which was used to analyze the microcosmic and high-frequency processing mechanism of fluid structure interaction between circulation valve and liquid of hydraulic shock absorber. The fluid mesh distortion was controlled by the CEL language, and the fluid struc^tre interaction mathematical model was established. The finite element model was established by ANSYS CFX software and was analyzed by dynamic mesh technique. The local sensitive computational area was meshed by prismatic grid, which could reduce the negative volume problem during the simulation. The circulation valve and liquid of hydraulic shock absorber were simulated and analyzed under the condition of sinusoidal inlet velocity loads. Flow characteristic and dynamics characteristic were obtained. The pressure distribution and the displacement of circulation value were obtained, and the acceleration curve of circulation valve was simulated and analyzed. The conformity of the final simulation results with the experimental datum indicates that this method is accurate and reliable to analyze the dynamics characteristic between circulation valve and liquid of hydraulic shock absorber, which can provide a theoretical foundation for optimizing hydraulic shock absorber in the future.展开更多
Thermal decomposition of 21 kinds of binary mixtures between typical medical compositions was investigated under nitrogen conditions by dynamic thermogravimetric analysis(TGA) at 25–800 °C. The weighed sum metho...Thermal decomposition of 21 kinds of binary mixtures between typical medical compositions was investigated under nitrogen conditions by dynamic thermogravimetric analysis(TGA) at 25–800 °C. The weighed sum method(WSM) coupled with thermal analysis was applied to study the interaction between components. Then, co-pyrolysis kinetic model of the binary mixtures(tube for transfusion(TFT) and gauze) was established to verify the reliability of conclusions. The results show the follows. 1) Strong or weak interactions are shown between binary mixtures containing polyvinyl chloride(PVC), the main ingredient of TFT. The addition of other medical waste could enhance first stage decomposition of TFT. While, the secondary stage pyrolysis may be suppressed or enhanced or not affected by the addition. 2) There exists no interaction between catheter and other component, the DTG peak temperature representing Ca CO3 decomposition in catheter fraction is obviously lower than that of pure catheter; while,the shape of DTG peak keeps unchanged. 3) No evident reaction occurs between the other mix-samples, it is considered that their co-pyrolysis characteristics are linear superposition of mono-component pyrolysis characteristics.展开更多
文摘TAR DNA结合蛋白43(transactive response DNA binding protein 43,TDP-43),一种可变剪切因子,可以特异性地结合富含TG序列的DNA,涉及多种神经退行性疾病.分子动力学模拟方法虽然是研究分子间相互作用强有力的工具,但它非常耗时,且难以对有大的构象变化的体系进行充分采样来研究其变构行为.本工作使用粗粒化的基于弹性势的高斯网络模型(Gaussian network model,GNM)研究人TDP-43与靶标DNA间相互作用的动力学.进一步地,利用本课题组之前提出的基于GNM的热力学循环方法识别TDP-43与DNA相互作用的关键残基,其微扰引起了大的结合自由能的变化.DNA结合后,TDP-43上富含正电残基的loop1和loop3片段有较大的柔性损失,这反映了它们在识别和结合中的诱导契合作用.另外发现,基于热力学循环的方法不仅识别到一些与DNA特异性相互作用有关的重要残基,而且识别到一些远离结合界面但在结合引起的分子构象变化中发挥重要作用的残基.本研究有助于理解TDP-43与DNA的特异性相互作用,可为药物设计提供重要信息,另外该方法可以很方便地拓展到其他蛋白质-核酸相互作用动力学的研究.
基金Project(51275542) supported by the National Natural Science Foundation of Chinaproject(CDJXS12110010) supported by the Fundamental Research Funds for the Central Universities of China
文摘Based on the working principle and the damping characteristic of hydraulic shock absorber, a fluid structure interaction method was presented, which was used to analyze the microcosmic and high-frequency processing mechanism of fluid structure interaction between circulation valve and liquid of hydraulic shock absorber. The fluid mesh distortion was controlled by the CEL language, and the fluid struc^tre interaction mathematical model was established. The finite element model was established by ANSYS CFX software and was analyzed by dynamic mesh technique. The local sensitive computational area was meshed by prismatic grid, which could reduce the negative volume problem during the simulation. The circulation valve and liquid of hydraulic shock absorber were simulated and analyzed under the condition of sinusoidal inlet velocity loads. Flow characteristic and dynamics characteristic were obtained. The pressure distribution and the displacement of circulation value were obtained, and the acceleration curve of circulation valve was simulated and analyzed. The conformity of the final simulation results with the experimental datum indicates that this method is accurate and reliable to analyze the dynamics characteristic between circulation valve and liquid of hydraulic shock absorber, which can provide a theoretical foundation for optimizing hydraulic shock absorber in the future.
基金Projects(51105269,51406133)supported by the National Natural Science Foundation of ChinaProject supported by the ScientificResearch Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,ChinaProject supported by the Ministry ofEducation Key Laboratory Program,China
文摘Thermal decomposition of 21 kinds of binary mixtures between typical medical compositions was investigated under nitrogen conditions by dynamic thermogravimetric analysis(TGA) at 25–800 °C. The weighed sum method(WSM) coupled with thermal analysis was applied to study the interaction between components. Then, co-pyrolysis kinetic model of the binary mixtures(tube for transfusion(TFT) and gauze) was established to verify the reliability of conclusions. The results show the follows. 1) Strong or weak interactions are shown between binary mixtures containing polyvinyl chloride(PVC), the main ingredient of TFT. The addition of other medical waste could enhance first stage decomposition of TFT. While, the secondary stage pyrolysis may be suppressed or enhanced or not affected by the addition. 2) There exists no interaction between catheter and other component, the DTG peak temperature representing Ca CO3 decomposition in catheter fraction is obviously lower than that of pure catheter; while,the shape of DTG peak keeps unchanged. 3) No evident reaction occurs between the other mix-samples, it is considered that their co-pyrolysis characteristics are linear superposition of mono-component pyrolysis characteristics.
