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Prof. Ling Miao
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Summer School Lectures:
- A brief review of basic statistical mechanics;
- Lateral molecular organization and molecular conformational order in lipid-cholesterol membranes, and sterol evolution;
- Mesoscopic and macroscopic morphology of fluid membranes: membrane elastic properties;
- Effect of in-plane molecular organizations on membrane elasticity and morphology.
STATISTICAL PHYSICS OF FLUID MEMBRANES (2 lectures)
Fluid membranes are the most essential structural components in living cells. They are bilayers of nanometer thickness, comprising small lipid molecules and proteins. The structure and physical properties of the membranes provide the necessary material support for a wide range of biological functions in living cells.Viewed from the standpoint of statistical physics, fluid membranes are soft interfaces with internal structures in their intrinsic two-dimensional space. The physical phenomena displayed by the membranes are rich and complex, spanning many decades of length and time scales. First, owing to the complexity and diversity in chemical structures of the molecular constituents, there exist a multitude of degrees of freedom in the intrinsic two dimensions, giving rise to complex two-dimensional (in-plane) ordering phenomena. Secondly, the membranes possess very unusual elastic properties: while being strongly resistant to lateral mechanical stretching or compression, they are highly flexible, or soft, towards surface deformations and can therefore fluctuate strongly in the ``third dimension''. Consequently, the mesoscopic- and macroscopic-scale morphology of the membranes is a demonstration of a delicate, yet important, role of fluctuating geometry in soft-material physics. Finally, the in-plane ordering processes can influence the elastic properties, leading to coupling between the in-plane molecular ordering to the membrane morphology.
The lectures are intended to give a review of some of the theoretical models and approaches that deal with the different physical aspects of fluid membranes. Some relevant experiments and biological context will also be discussed. The topics are (if time permitting):