Waugh R E
Biophys J. 1982 Apr;38(1):19-27. doi: 10.1016/S0006-3495(82)84526-8.
Recent observations indicate that it is possible to form tethers from large phospholipid vesicles. The process of tether formation is analyzed using a continuum mechanical approach to obtain the surface viscosity of the bilayer in terms of experimentally measurable parameters. The membrane is treated as a two-dimensional isotropic material which deforms a constant area. The constitutive equation relates the maximum surface shear resultant to the rate of deformation via the surface viscosity coefficient. The force which acts to increase the tether length is generated by fluid moving past the vesicle. The magnitude of the force is estimated from Stoke's drag equation. The analysis predicts that there is a critical force necessary to produce an increase in the tether length. A dimensionless tether growth parameter is defined, and its value is obtained as a function of the ratio of the applied force on the vesicle to the critical force. This relationship is independent of both the size of the vesicle and the radius of the tether. Knowing the force on the vesicle, the critical force, and the rate of tether growth, the surface viscosity can be calculated.
最近的观察表明，由大型磷脂囊泡形成系链是可能的。使用连续介质力学方法分析系链形成过程，以便根据实验可测量参数获得双层膜的表面粘度。将膜视为二维各向同性材料，其在恒定面积下变形。本构方程通过表面粘度系数将最大表面剪切合力与变形速率联系起来。促使系链长度增加的力是由流过囊泡的流体产生的。该力的大小根据斯托克斯阻力方程估算。分析预测，要使系链长度增加，存在一个临界力。定义了一个无量纲系链生长参数，并将其值作为施加在囊泡上的力与临界力之比的函数来获得。这种关系与囊泡大小和系链半径均无关。知道作用在囊泡上的力、临界力和系链生长速率，就可以计算表面粘度。
