MOLECULAR FORCES

在过去的几个月里，埃文埃文斯和PI解决了长期存在的问题。 与相邻膜的机械运动相关的问题， 线性大分子之间的长程作用力。 具体地说，我们已经推导出公式， 多层晶格的水化，静电和货车der 层与层之间的力。 我们已经确认了 这些波动对相互作用的贡献 层次。 我们成功地解释了一个长期存在的异常现象， 磷脂双层膜之间静电力的衰减。 这一显然抽象的成就是第一步，也是艰难的一步， 学习将力与分子运动联系起来， 分子组装 我们的战略现在已经引导我们设计了几个 通过X射线散射测量分子运动的实验。 与R. P.兰德和S. M. Gruner PI一直在测量 脂质组装体，最显著的是在倒六边形中的磷脂 相位 这些研究旨在阐明可能的中间体 在融合过程中的脂质状态，并在确定能量 膜孔形成的因素。 E. Barouch和PI正在检查一组数学解决方案， 各种几何形状的静电双层问题。 的对象 这个检查是为了测试一种流行的方法，Derjaguin近似， 用于解释表面之间的力的测量。

During the past months, Evan Evans and the PI have solved the long-standing problem of relating the mechanical motion of neighboring membranes or linear macromolecules to the long-range forces acting between them. Specifically, we have derived formulae giving the undulations in a multilamellar lattice in terms of the hydration, electrostatic and van der Waals forces between layers. We have identified the additional contributions of these undulations to the total interactions between layers. We have succeeded in explaining a long-standing anomaly in the decay of electrostatic forces between phospholipid bilayer membranes. This apparently abstract achievement is a first and difficult step in learning to relate forces to molecular motion, a central problem in molecular assembly. Our strategy has now lead us to design several experiments to measure molecular motion from x-ray scattering. With R.P. Rand and S.M. Gruner, the PI has been measuring the stability of lipid assemblies, most notably of phospholipids in the inverted hexagonal phase. These studies are aimed at illuminating the possible intermediate states of lipids during fusion processes and at identifying the energetic factors in membrane pore formation. E. Barouch and the PI are examining a set of methematical solutions of the electrostatic double layer problem in various geometries. The object of this examination is to test a popular method, the Derjaguin approximation, used to interpret measurements of forces between surfaces.