Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor
Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor
复制标题
用时均均方位移张量阐明聚合物模型质心运动中的脉动扩散率
DOI：
10.1103/physreve.96.042501
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发表时间：
2017
影响因子：
2.4
通讯作者：
Tomoshige Miyaguchi
中科院分区：
文献类型：
--
作者：
J. Wang;Y. Muroya;T. Kuniya;[2] Y. Muroya and T. Kuniya;國谷紀良;國谷紀良;Tomoshige Miyaguchi
越来越多的研究表明，大分子的扩散系数依赖于时间，并且是随机波动的。在这里，开发的方法来阐明这种波动的扩散率从轨迹数据。时间平均均方位移（MSD），在单粒子跟踪（SPT）实验中的一个常见的工具，被推广到一个二阶张量与扩散率的幅度和方向的波动可以清楚地检测。该方法被用来分析四个基本的聚合物模型的质心运动：劳斯模型，Zimm模型，爬行模型，和刚性棒状聚合物。结果发现，这些模型表现出明显不同类型的大小和方向波动的扩散。这是本方法优于先前方法的优点，例如遍历性破坏参数和非高斯参数，因为使用这些参数中的任何一个都难以区分四种聚合物模型的动力学。此外，本方法的时间平均MSD张量可以用来分析在SPT实验中获得的轨迹数据。
There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer. It is found that these models exhibit distinctly different types of magnitude and orientation fluctuations of diffusivity. This is an advantage of the present method over previous ones, such as the ergodicity-breaking parameter and a non-Gaussian parameter, because with either of these parameters it is difficult to distinguish the dynamics of the four polymer models. Also, the present method of a time-averaged MSD tensor could be used to analyze trajectory data obtained in SPT experiments.