Kantsler Vasiliy, Segre Enrico, Steinberg Victor
Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100 Israel.
Phys Rev Lett. 2008 Jul 25;101(4):048101. doi: 10.1103/PhysRevLett.101.048101. Epub 2008 Jul 21.
We present results on the stretching of single tubular vesicles in an elongation flow toward dumbbell shapes, and on their relaxation. A critical strain rate epsilonc exists; for strain rates epsilon<epsilonc, the vesicle remains tubular but fluctuates, though its steady state extension increases with the strain rate epsilon. Above epsilonc, first a shape transition to dumbbell occurs, and then high order shape modes become unstable, leading to a pearling state. We have quantitatively characterized the transition and found a scaling of epsilonc with the system parameters. A remarkable feature of vesicle tube behavior around the critical point is a slowdown of the vesicle relaxation to the final extended state in the vesicle stretching. Such feature is similar to that found in continuous phase transitions and to the critical effects recently observed for polymer molecules near the coil-stretch transition in elongation flow.
我们展示了关于单个管状囊泡在向哑铃形状的伸长流中拉伸及其松弛的结果。存在一个临界应变率εc；对于应变率ε<εc，囊泡保持管状但会波动，尽管其稳态伸长随应变率ε增加。在εc之上，首先会发生向哑铃形状的形状转变，然后高阶形状模式变得不稳定，导致出现串珠状状态。我们已经对该转变进行了定量表征，并发现了εc与系统参数之间的标度关系。临界点附近囊泡管行为的一个显著特征是，在囊泡拉伸过程中，囊泡向最终伸展状态的松弛变慢。这种特征类似于在连续相变中发现的特征，也类似于最近在伸长流中聚合物分子接近线圈 - 拉伸转变时观察到的临界效应。
