CAREER: The Statistical Mechanics of Filamentous Assemblies

技术总结该职业奖支持理论和计算研究，以及纳米级细丝的超分子组装的教育。生物丝本身的柔韧性和相互作用的复杂性给理论研究带来了挑战。这些影响是由长波长的物理，代表两个软变形沿着丝，以及丝间包装geometrical.The PI的集体效应将调查的统计和热力学性质的丝状组件，从生物丝的共同结构。也就是说，生物丝普遍是长的、柔性的和螺旋状的。本研究有三个目的：1）确定手性诱导的拓扑缺陷在有限直径纤维束形成中的作用; 2）建立蛋白质介导的丝状肌动蛋白成束的统计理论; 3）探索纯和非均匀纤维束组装结晶的统计力学。项目（1）：PI将建立一个基本的后果之间的几何挫折的二维和手性有序的材料在密集的生物丝束的上下文中。PI将集中在屏幕长程应力，这是由相邻的细丝之间的手征相互作用本身引起的向错所发挥的作用。PI的目的是阐明手性对分子组装的影响，并提供深入了解生物细丝的组装机制，这些生物细丝的尺寸是固有的限制。项目（2）：PI旨在构建一个统计力学框架，一个耦合的晶格气和晶格自旋模型，探索平行肌动蛋白束的组装热力学。我们的目标是要确定如何各自的螺旋和六重对称性的f-肌动蛋白和束组件之间的内在挫折引起的交联蛋白质的合作结合，并影响束的形成。项目（3）：PI将研究丝状系统的关键特性，因为它们通过一个异常复杂的相变，从二维液晶到真正的三维固体。PI进一步旨在评估淬火杂质对多分散长丝结晶的作用，并扩大我们对软材料无序作用的认识。教育部分支持开发一个新的教育项目，利用现有的中心和教师资源为本科生创建一个理论上的软物质研究暑期项目。该计划旨在提高学生的技能，使他们能够参与正在进行的理论研究项目。该计划向学生介绍了建模软材料的方法和挑战，并在这一领域的研究的兴奋。非技术性总结这个职业奖支持理论和计算研究，并对具有纳米尺度的大分子组成的细丝组装教育？十亿分之一米像这样的纤维束组装体在生物细胞内发现，并在赋予它们结构完整性方面发挥重要作用。该奖项支持研究，以了解丝状组件如何组织成更复杂的结构。这对丝状组件的结构和机械性能具有重要影响。这项研究的各个方面将与使用X射线研究细胞中纤维束的实验工作合作进行。PI旨在揭示基本原理，这些原理也适用于纳米级结构的新型合成材料的设计。这项研究是数学和物理科学与生物学边界基础研究的一个例子，有可能促进两者的发展。教育部分支持开发新教育项目的努力，该项目利用现有中心和教师资源创建一个新的教育项目软物质研究理论暑期课程为本科生。该计划旨在提高学生的技能，使他们能够参与正在进行的理论研究项目。该计划向学生介绍了建模软材料的方法和挑战以及该领域研究的兴奋。

TECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education on supermolecular assemblies of nanoscale filaments. Biofilaments present inherent challenges to theoretical study owing to the flexibility of the filaments themselves and the complexity of interactions among them. These effects are governed by long-wavelength physics, representing both soft deformations along filaments, as well as collective effects of inter-filament packing geometry.The PI will investigate the statistical and thermodynamic properties of filamentous assemblies that derive from the common structure of biological filaments. Namely, biofilaments are universally long, flexible and helical. The research addresses three aims: 1) establish the role of chirally-induced topological defects in finite-diameter bundle formation; 2) build a statistical theory of protein-mediated bundling of filamentous actin; and 3) explore the statistical mechanics of crystallization of pure and inhomogeneous filament assemblies.Project (1): The PI will establish a fundamental consequence of the geometric frustration between two dimensional and chirally ordered materials in the context of dense biofilament bundles. The PI will focus on the role played by disclinations that screen long-range stresses, which are themselves induced by chiral interactions between neighboring filaments. The PI aims to illuminate the influence of chirality on molecular assembly and provide insight into assembly mechanisms of biological filaments that are inherently limited in size. Project (2): The PI aims to construct a statistical mechanical framework, a coupled lattice-gas and lattice spin model, to explore the assembly thermodynamics of parallel actin bundles. The goal is to determine how an intrinsic frustration between the respective helical and six-fold symmetries of f-actin and bundle assemblies gives rise to cooperative binding of cross-linking proteins and influences bundle formation. Project (3): The PI will investigate the critical properties of filamentous systems as they pass through an unusually complex phase transition from two dimensional liquid-crystals to true three dimensional solids. The PI further aims to assess the role of quenched impurities inherent to crystallization of polydisperse filaments and expand our knowledge of the role of disorder in soft materials.The education component supports an effort to develop a new educational program that leverages existing center and faculty resources to create a Soft Matter Research in Theory summer program for undergraduate students. The program is designed to enhance the skills of students and enable them to participate in ongoing theoretical research projects. This program introduces students to the methods and challenges of modeling soft materials and the excitement of research in this area.NONTECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education on assemblies of filaments composed of large molecules that have dimensions on scale of a nanometer ? a billionth of a meter. Filamentous assemblies like these are found inside biological cells and play an important role in giving them structural integrity. This award supports research to understand how filamentous assemblies organize themselves into more complex structures. This has important consequences for the structural and mechanical properties of filamentous assemblies. Aspects of the research will be done in collaboration with experimental efforts that use x-rays to study filament bundling in cells. The PI seeks to uncover fundamental principles that will also apply to the design of new synthetic materials that are structured on the nanometer scale.This research is an example of fundamental research in the mathematical and physical sciences at the boundaries with biology which has the potential to advance both.The education component supports an effort to develop a new educational program that leverages existing center and faculty resources to create a Soft Matter Research in Theory summer program for undergraduate students. The program is designed to enhance the skills of students and enable them to participate in ongoing theoretical research projects. This program introduces students to the methods and challenges of modeling soft materials and the excitement of research in this area.