John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2022 Feb 4;128(5):058101. doi: 10.1103/PhysRevLett.128.058101.
A thin-walled tube, e.g., a drinking straw, manifests an instability when bent by localizing the curvature change in a small region. This instability has been extensively studied since the seminal work of Brazier nearly a century ago. However, the scenario of pressurized tubes has received much less attention. Motivated by rod-shaped bacteria such as E. coli, whose cell walls are much thinner than their radius and are subject to a substantial internal pressure, we study, theoretically, how this instability is affected by this internal pressure. In the parameter range relevant to the bacteria, we find that the internal pressure significantly postpones the onset of the instability, while the bending stiffness of the cell wall has almost no influence. This study suggests a new method to infer turgor pressure in rod-shaped bacteria from bending experiments.
薄壁管，例如饮用吸管，在局部区域使曲率发生变化时会表现出不稳定性。这种不稳定性自近一个世纪前 Brazier 的开创性工作以来就得到了广泛的研究。然而，受压管的情况受到的关注要少得多。受类似 E. coli 的杆状细菌的启发，它们的细胞壁比其半径薄得多，并承受着相当大的内部压力，我们从理论上研究了这种不稳定性如何受到这种内部压力的影响。在所研究的与细菌相关的参数范围内，我们发现内部压力显著延迟了不稳定性的发生，而细胞壁的弯曲刚度几乎没有影响。这项研究为从弯曲实验中推断杆状细菌的膨压提供了一种新方法。
