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采用粗粒化的分子动力学模拟研究了跨膜多肽,lysine-flanked peptide(KALP),对第四代聚酰胺-胺(PAMAM)树枝形分子形态结构的影响.考虑了中性和酸性两种不同pH环境下两个分子间的相互作用行为.计算了PAMAM分子的回转半径、非球形因子、相对于树枝形分子质心的径向密度分布函数,和两分子间的平均力势.模拟发现在两种pH环境下KALP多肽对树枝形分子的大小、形状及密度分布影响不大,证实了PAMAM树枝形分子内部有一定空间容纳KALP多肽分子.自由能的计算结果表明酸性pH环境中PAMAM分子排斥KALP肽,无法形成复合结构;在中性pH环境中,两种分子也不容易形成稳定的复合结构. 相似文献
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探索自驱粒子形状对自组装结构和动力学的影响是软物质研究的前沿课题.组装基元形成的寡聚体及其动力学是大量粒子形成组装结构的基础.本文设计了一种“十”字形自驱粒子,发现其可以形成数种不同构型的寡聚体,计算了寡聚体(二、三、四聚体)的均方位移、角速度、角速度分布概率、轨迹曲率分布概率等.寡聚体的运动行为可分为两类:一类是合力为零但力矩不为零,寡聚体进行小半径的偏心旋转;另一类是合力不为零力矩也不为零,寡聚体呈现大半径的偏心旋转.寡聚体的平动动力学在短时间尺度(大致约为1—2 s,与其角速度有关)都呈现超扩散现象,但转动速度受寡聚体结构影响;力矩越大,转动惯量越小,角速度越大.对于三聚体,轨迹曲率与角速度有关,角速度越大,曲率也越大. 相似文献
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We investigate the transport properties and mechanical response of glassy hard disks using nonlinear Langevin equation theory.We derive expressions for the elastic shear modulus and viscosity in two dimensions on the basis of thermalactivated barrier-hopping dynamics and mechanically accelerated motion.Dense hard disks exhibit phenomena such as softening elasticity,shear-thinning of viscosity,and yielding upon deformation,which are qualitatively similar to dense hard-sphere colloidal suspensions in three dimensions.These phenomena can be ascribed to stress-induced "landscape tilting".Quantitative comparisons of these phenomena between hard disks and hard spheres are presented.Interestingly,we find that the density dependence of yield stress in hard disks is much more significant than in hard spheres.Our work provides a foundation for further generalizing the nonlinear Langevin equation theory to address slow dynamics and rheological behavior in binary or polydisperse mixtures of hard or soft disks. 相似文献
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We simulate a two-dimensional model of a round soft boundary enclosed with self-propelled particles. Persistent motion drives these particles to accumulate near the boundary, thereby dramatically deforming the boundary shape through collisions. Quantitative analyses of the boundary shape and the particle distribution show that there are two typical regimes in the variation of the morphology with the increase of self-propulsion of particles. One is under small forces, characterized by the radially inhomogeneous distribution of particles and the suppression of local fluctuations of the almost round boundary, and the other is under large forces, featured by the angularly inhomogeneous distribution of particles and the global shape deformation of the boundary. These two features are strongly cooperative. We also find different mechanisms in the particle relocation at low and high particle concentrations. 相似文献
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