基于支持向量机的神经元形态分类

针对神经元的空间几何形态特征分类问题以及神经元的生长预测问题进行了探讨.结合神经元的形态数据,分别建立了基于支持向量机的神经元形态分类模型、基于主成分分析和支持向量机的神经元分类模型以及基于遗传算法和RBF网络的神经元生长预测模型,在较合理的假设下,对各个模型进行求解,得到了较理想的结果.     

含CoNx中心的石墨烯电催化氧还原反应机理研究

采用理论计算方法深入研究了两种含三配位CoN_x(x=2,3)中心的石墨烯(CoN_x-G)催化剂在氧还原反应(ORR)中的催化机理. 在这两种催化剂表面, ORR的最低能量反应路径遵循相同的机制: O_{2 (ads)}分子首先加氢还原为OOH_(ads), 随后OOH_(ads)加氢解离为两个OH_(ads), 最终OH_(ads)继续加氢还原为产物水. 在CoN₂-G上, 整条反应路径中OH_(ads)还原为H₂O_(ads)具有最高能垒; 而在CoN₃-G表面, O_2(ads)还原为OOH_(ads)具有最高能垒. 相比CoN₂-G, CoN₃-G具有较低的最高势垒, 更佳的结构对称性, 更负的形成能, 且在ORR过程中Co中心始终保持正电荷, 有利于含氧中间体的活化. 因此, CoN₃-G表现出比CoN₂-G更优良的ORR催化性能, 归因于配位的三个N原子对Co位点电子结构的优化以及体系稳定性的增强.     

基于GROMACS软件的本科生酶工程创新实验项目设计*——微生物谷氨酰胺转胺酶在水溶液中的分子动力学模拟

基于分子动力学模拟软件GROMACS设计了微生物谷氨酰胺转胺酶在不同温度水环境下的分子动力学模拟实验,通过计算模拟过程中酶蛋白主链动力学,分子内氢键数目,回转半径以及溶剂可接触表面积的变化,分析温度对酶的结构与功能造成的影响。该模拟实验可帮助学生:(1)掌握蛋白质分子在水溶液中动力学模拟的方法;(2)理解温度对酶结构稳定性和活性造成的影响;(3)了解分子运动特性的生物学的意义;(4)学习酶工程研究的新手段。     

Polarization and exchange effects in elastic scattering of electron with atoms and ions

Laser-induced electron diffraction(LIED), in which elastic scattering of the returning electron with the parent ion takes place, has been used to extract atomic potential and image molecular structures with sub-?A precision and exposure time of a few femtoseconds. So far, the polarization and exchange effects have not been taken into account in the theoretical calculation of differential cross section(DCS) for the laser-induced rescattering processes. However, the validity of this theoretical treatment has never been verified. In this work, we investigate the polarization and exchange effects on electron impact elastic scattering with rare gas atoms and ions. It is found that, while the exchange effect generally plays a more important role than the polarization effect in the elastic scattering process, the exchange effect is less important on electron–ion collisions than on electron–atom collisions, especially for scattering in backward direction. In addition, our calculations show that, for electron–atom collisions at incident energies above 50 e V, both the polarization and exchange effects can be safely neglected, while for electron–ion collisions, both the polarization and exchange potentials do not make substantial contributions to the DCS at incident energies above 20 e V and scattering angles larger than 90?. Our investigation confirms the validity of the current LIED method.