Li Longfei, Liu Peng, Chen Ke, Zheng Ning, Yang Mingcheng
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Beijing National Laboratory for Condensed Matter Physics and Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Soft Matter. 2022 Jun 8;18(22):4265-4272. doi: 10.1039/d2sm00469k.
The active depletion torque experienced by two anisotropic objects in an active bath is a conceptional generalization of the equilibrium entropic torque. Using Brownian dynamics simulations, we compute the active depletion torque suffered by two passive rods immersed in an ensemble of active Brownian particles. Our results demonstrate that the active depletion torque is qualitatively different from its passive counterpart. Interestingly, we find that the active depletion torque can be greatly affected by the external constraint applied on the rotational degree of freedom of the rods, and even the direction may be changed with the orientational constraint, which is in contrast to the equilibrium depletion torque. The main reason for the remarkable features of the active depletion torque is that the active particles can significantly accumulate in the vicinity of the rods due to persistent self-propulsion, which is sensitively dependent on the constraint strength and the rod configurations. Our findings could be relevant for understanding the self-assembly and dynamics of anisotropic macromolecules in living environments.
在活性浴中，两个各向异性物体所经历的主动耗散扭矩是平衡熵扭矩的概念性推广。通过布朗动力学模拟，我们计算了浸没在活性布朗粒子系综中的两根被动棒所遭受的主动耗散扭矩。我们的结果表明，主动耗散扭矩与其被动对应物在性质上有所不同。有趣的是，我们发现主动耗散扭矩会受到施加在棒旋转自由度上的外部约束的极大影响，甚至其方向可能会随着取向约束而改变，这与平衡耗散扭矩形成对比。主动耗散扭矩显著特征的主要原因是，由于持续的自推进，活性粒子会在棒的附近显著聚集，这敏感地依赖于约束强度和棒的构型。我们的发现可能有助于理解生物环境中各向异性大分子的自组装和动力学。
