Application of Theory of Super Lubricity of Minimum Entropy Welding

从机械工程的角度来看，细菌鞭毛马达具有几个有趣的特点；它的最大转速为17,000 HZ，转子直径约为50 nm。在自然界中，使用旋转运动的驱动系统只存在于单细胞生物细菌中，而跳动运动在非细菌世界中占主导地位。既然生命在进化过程中选择了更有效的机制，那么了解细菌为什么选择旋转运动而不是跳动运动的原因是很有趣的。另一方面，电机作为驱动系统在工程中被广泛应用。当我们考虑微摩擦学中润滑的困难时，它发生在一个像细菌一样小的世界里，关于fagellar马达的知识将有助于解决这些问题。20世纪摩擦学和润滑工程在宏观尺度上已经达到了一个范式，即工程中大多数固体摩擦都可以用库仑-阿蒙顿定律和流体膜润滑来很好地描述，润滑的最佳策略是流体膜润滑。在这里，偏离库仑定律，如橡胶摩擦或超润滑被认为是例外情况。现在，进入21世纪，围绕摩擦学的环境正在发生巨大变化。由于该范式并不总是适用于诸如微摩擦学等新兴领域，因此我们必须采用一些其他的摩擦和润滑范式。在微摩擦学中，理想结晶表面之间有时会发生摩擦。分子作用力在这种摩擦中起着重要的作用。因此，库仑定律不再有效；因为这是固体摩擦的实验规律。在分子薄的液体薄膜中，分子力影响液体的行为。当薄膜粘度（或粘度上升）是由分子作用力引起时，流体膜润滑方法将不再是最好的。到目前为止，我们对微机械的润滑还没有足够的了解。在某些细菌的鞭毛马达中，有一种叫做PL环的套管，它允许旋转轴穿透坚硬的细胞壁。PL环的存在表明我们的经典润滑方法在微摩擦学中可能仍然有效。在最近的研究中，我们利用经典流体动力润滑理论和薄膜粘度参数值计算了PL环的摩擦学参数。结果表明，由此计算出的摩擦值过高，不利于电机高速运行，表明经典方法的有效性。在本研究中，我们证明了流体动力润滑的一般理论并不是一个足够的工具来分析环内的润滑。我们还计算了Stokes方程的尺度不变性，并考虑了其他可能的润滑机制。少

From the viewpoint of mechanical engineering, the bacterial flagellar motor has several interesting features ; it rotates at a maximum speed of 17,000 HZ, and the diameter of the rotor is about 50 nm. In nature, the driving system using rotational motion is found only in single-celled organisms bacteria, while beating motion dominates the non-bacterial world.Since life chooses the more efficient mechanism in the process of evolution, it is interesting to know the reasons why bacteria chose rotational motion rather than beating motion.On the other hand, motors are widely used as driving systems in engineering. When we consider the difficulty of lubrication in microtribology which occurs in a world as small as bacteria, knowledge about the f1agellar motor will be useful to solve the problems.In the 20th century, tribology and lubrication engineering on the macroscale have reached a paradigm that most of the solid frictions in engineering can be well described by Coulomb-Amonton's law and … More that the best strategy of lubrication is fluid film lubrication. Here, deviations from Coulomb's law such as the friction of rubber or super-lubricity are considered to be exceptional cases.Now, entering the 21st century, the circumstances around tribology are drastically changing. Since the paradigm is not always applicable to newly emerging areas such as microtribology, we have to employ some other paradigms for friction and lubrication.In microtribology, friction between ideal crystalline surfaces may sometimes occur. Molecular forces would play an essential role in this kind of friction. Therefore, Coulomb's law is not powerful anymore ; as it is an experimental rule for solid friction. Molecular forces affect the behavior of liquids in molecularly thin liquid films. When thin film viscosity (or a viscosity rise) is duced by molecular forces, the fluid film lubrication method will not be the best anymore. Until now, we have not obtained enough knowledge about the lubrication in micromachines.In the flagellar motor of some bacterial species, there is a bushing, called the PL ring, which allows the rotating shaft to penetrate the rigid cell wall. The existence of the PL ring suggests that our classical method of lubrication might be still valid in microtribology. In a recent study, we calculated parameters in the tribology of the PL ring using theory of the classical hydrodynamic lubrication and the parameter values in thin film viscosity. The results showed that the friction values thus calculated are too high to operate the motor at high speeds, indicating invalidity of the classical method.In this study, we show that the ordinary theory for hydrodynamic lubrication is not an adequate tool for analysis of lubrication in the PL ring. We also calculate the scale invariance of the Stokes equation and consider other possible lubrication mechanisms. Less