Interparticle-friction-induced anomalous colloid structure

Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems,focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids.We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations,and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems.These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.

约束促进活性布朗粒子异质成核

通过计算机模拟,研究了施加在惰性棒上的简谐约束(平动和转动)对含有惰性棒的二维活性布朗粒子浴成核和相分离的影响。结果表明,惰性棒所受平动和转动约束均可显著促进活性粒子异质成核并产生运动诱导相分离,原因是约束减慢了惰性棒的动力学,增加了活性粒子在惰性棒周围聚集几率和粒子间碰撞程度,从而降低了初始成核对于活性粒子的活性和面积分数(等效于面密度)的要求。研究结果为低面积分数、低活性的活性粒子相分离提供了新思路。

速度外场驱动下活性粒子流瓶颈堵塞的“欲速则不达”现象

增加个体速度或个体间挤压强度,个体通过瓶颈的流量反而明显降低,这就是著名的“欲速则不达”现象。本文利用分子动力学模拟研究了在不同速度场驱动下,自驱动力对活性粒子瓶颈堵塞特性的影响。随着粒子自驱动力的增加,活性粒子的整体流量反而减少。基于粒子的阻塞概率与互补累积分布函数的拟合幂律指数,解释了尽管自驱动力可有效增强粒子的运动能力,但同时也引起堵塞事件的增加,最终造成整体流量下降。活性粒子瓶颈流作为典型的复杂系统,可帮助学生理解个体最优化并不一定会使整体效率最优的物理思想,并且其对数据处理统计分析水平要求较高,这对本科生学术能力的训练和科学素养的培养很有帮助。