Microscopic dynamics of soft systems

我开发了新的方法，通过观察材料的微观动力学来提取材料的信息。我特别感兴趣的是深入了解这些系统是如何组织和传播压力的，以及它们是如何移动的。这种见解对于帮助物理学家理解软材料和复杂流体（如生物细胞的支架）具有非凡的重要性，而这种基本的理解正是激励我的动力。当然，这样的理解也有助于一系列的应用，从食品科学到生物技术和生物医学。在这个提议中，我描述了我计划如何利用我实验室的技术来推动我们对微观结构和动力学决定硬球和弱吸引力球在冻结和玻璃形成（即凝固）时的相行为和宏观动力学特性的理解。为了做到这一点，我将使用一个可以控制键长的胶体模型系统，这样我就可以研究不同的固体相作为键长的函数，从而直接观察到相同模型系统中的一些基本物理现象，而这是我们在原子系统中无法做到的。我建议使用微米大小的探针颗粒的热运动的物理内容，使用一种称为微流变学的技术，来揭示基于肌动蛋白微管的细胞骨架模型的机械和材料信息。这一提议的工作建立在我在这两个领域的既定工作的基础上，推动了新的基本方法，导致对重要的硬球模型系统的新见解，以及对冷冻，玻璃形成，细胞设计原则，生物聚合物的物理学和微流变学方法本身的一般性的更深入的理解。

I develop new ways of extracting information about materials by observation of their microscopic dynamics. My particular interest in doing this is to gain insight regarding how these systems organize and propagate stress, in addition to how they move about. Such insight is of extraordinary importance in helping physicists understand soft materials and complex fluids such as the scaffolding of biological cells, and that fundamental understanding is what motivates me. Of course, such understandings can also assist a whole array of applications, from food science, to biotechnology and to biomedicine. In this proposal I describe how I plan to use the techniques coming out of my lab to push forward our understanding of the way in which microscopic structure and dynamics determine the phase behaviour and macroscopic dynamical properties in hard spheres and weakly attractive spheres upon freezing and glass formation-that is, upon solidification. To do this I will use a colloid model system in which the bond length can be controlled, so that I may investigate various solid phases as a function of the bond length, and thereby directly observe some fundamental physics in the same model system in ways we cannot in atomic systems. I propose to use the physical content of thermal motions of micrometer-sized probe particles, using a technique called microrheology, to reveal mechanical and material information about an actin-microtubule based model for the cell cytoskeleton. This proposed body of work builds on my established work in both these areas, pushing in new fundamental ways that lead to novel insights about the important hard sphere model system, and a deeper understanding of freezing, glass formation, the design principles of the cell, the physics of biopolymers, and the generality of the microrheology method itself.