Sadhukhan Poulomi, Schumann Ole, Heussinger Claus
Institute for Theoretical Physics, Georg-August University of Göttingen, Friedrich-Hund Platz 1, 37077, Göttingen, Germany,
Eur Phys J E Soft Matter. 2014 Jun;37(6):14. doi: 10.1140/epje/i2014-14058-5. Epub 2014 Jun 27.
We study the response of F-actin bundles to driving forces through a simple analytical model. We consider two filaments connected by reversibly bound crosslinks and driven by an external force. Two failure modes under load can be defined. Brittle failure is observed when crosslinks suddenly and collectively unbind, leading to catastrophic loss of bundle integrity. During ductile failure, on the other hand, bundle integrity is maintained, however at the cost of crosslink reorganization and defect formation. We present phase diagrams for the onset of failure, highlighting the importance of the crosslink stiffness for these processes. Crossing the phase boundaries, force-deflection curves display (frequency-dependent) hysteresis loops, reflecting the first-order character of the failure processes. We evidence how the introduction of defects can lead to complex elasto-plastic relaxation processes, once the force is switched off. Depending on, both the time-scale for defect motion and the crosslink stiffness, bundles can remain in a quasi-permanent plastically deformed state for a very long time.
我们通过一个简单的分析模型来研究F-肌动蛋白束对驱动力的响应。我们考虑由可逆结合的交联点连接并由外力驱动的两根细丝。可以定义负载下的两种失效模式。当交联点突然集体解离时，会观察到脆性失效，导致束的完整性灾难性丧失。另一方面，在韧性失效期间，束的完整性得以维持，但代价是交联点的重新组织和缺陷形成。我们给出了失效起始的相图，突出了交联刚度在这些过程中的重要性。越过相界时，力-挠度曲线显示出（频率相关的）滞后回线，反映了失效过程的一级特性。我们证明了一旦力被关闭，缺陷的引入如何导致复杂的弹塑性松弛过程。根据缺陷运动的时间尺度和交联刚度，束可以在很长一段时间内保持准永久的塑性变形状态。
