印度贾瓦哈拉尔·尼赫鲁高级科学研究中心Srikanth Sastry团队研究了活性粒子在体相和约束条件下的屈服行为。2025年3月31日出版的《自然—物理学》发表了这项成果。

自推进活性粒子密集组装中的集体行为发生在广泛的生物现象中，包括细胞和亚细胞生物组装的动态转变，如细胞骨架和细胞核。受对此类系统动力学中机械诱导变化的观察和约束几何形状的明显作用的启发，研究组表明流化转变与无定形固体的屈服大致相似，这与最近的建议是一致的。

然而，更具体地说，研究组发现，对于大但有限的持续时间，循环剪切变形下的屈服转变有一个详细的类比。流化转变伴随着驱动诱导退火、对系统初始状态的强烈依赖、达到稳态的时间尺度发散和扩散运动的不连续开始。他们还观察到过渡对持续时间和限制性质的显著依赖性。总的来说，该研究结果对受限几何结构中的生物组装具有重要意义，包括表观遗传细胞状态转换。

附：英文原文

Title: Yielding behaviour of active particles in bulk and in confinement

Author: Goswami, Yagyik, Shivashankar, G. V., Sastry, Srikanth

Issue&Volume: 2025-03-31

Abstract: Collective behaviour in dense assemblies of self-propelled active particles occurs in a wide range of biological phenomena, including the dynamical transitions of cellular and subcellular biological assemblies such as the cytoskeleton and the cell nucleus. Here, motivated by observations of mechanically induced changes in the dynamics of such systems and the apparent role of confinement geometry, we show that the fluidization transition broadly resembles yielding in amorphous solids, which is consistent with recent suggestions. More specifically, however, we find that a detailed analogy holds with the yielding transition under cyclic shear deformation, for large but finite persistence times. The fluidization transition is accompanied by driving-induced annealing, strong dependence on the initial state of the system, a divergence of timescales to reach steady states and a discontinuous onset of diffusive motion. We also observe a striking dependence of transition on persistence times and on the nature of confinement. Collectively, our results have implications for biological assemblies in confined geometries, including epigenetic cell-state transitions.

DOI: 10.1038/s41567-025-02843-7

Source: https://www.nature.com/articles/s41567-025-02843-7