CAREER: Statistical Mechanics of Cellular Structures

该职业奖支持与教育相结合的理论和计算研究，以获得对细胞材料物理特性的统一理解。从蜂窝到泡沫再到生物细胞，具有细胞结构的材料在自然界中无处不在。为了提高对细胞材料的理解，PI将采用跨学科的方法，结合物理学、几何学和生物学的知识和技术。器官表面覆盖着致密的细胞层，起到物理屏障的作用。虽然细胞通常不迁移，但在胚胎发育、形态发生、修复和重塑等基本过程中，细胞可以进行主动重排。在这些情况下，细胞层从类固体状态转变为类流体状态。这种惊人的转变传统上是在平面上的细胞的背景下研究的。然而，大多数器官的表面自然是非平坦的，由曲面组成，如球体、鞍形或圆柱体。表面曲率如何影响细胞运动在很大程度上仍然未知。为了解决这些问题，首席研究员将研究细胞如何在曲面上集体运动，以及曲率对它们表现为固体还是流体的作用。这些研究将产生可以在活胚胎和实验室培养组织中进行实验测试的预测。从生物组织中获得的知识将为PI调查其他细胞结构中刚性的起源提供灵感。这些包括实体中的力网或由随机连接的弹簧构成的机械网络。目标是发展细胞结构的设计原则，使其表现出不同寻常的机械性能，并利用它们来设计自然界中不易出现的功能材料。CAREER奖还支持与研究紧密结合的教育活动。其目标是增加第一次上物理课的学生的多样性和保留率，无论是在高中还是大学。PI将与K-12 STEM教育工作者合作，为物理入门课程设计非常规但易于理解的教学模块。这些模块将以生物物理学、流行病学和生物学为基础，同时与导论物理学中教授的基本物理概念建立联系。这些模块与传统的“教科书示例”有很大不同，将为学生提供关于物理概念的适用性和影响的大开眼界的体验。该职业奖支持综合理论和计算研究、推广和教育，旨在促进对细胞材料（包括生物组织、泡沫、颗粒填料及其力网络）的统计力学和集体行为的基本理解。在生物学背景下，该项目将研究受限于曲面上的多细胞集体的干扰/解除干扰过渡的性质，并阐明作为非零高斯曲率的独特结果而产生的相干角运动的起源。在非生物细胞结构中，PI将研究机械对偶性的后果。目标将涉及基于自应力状态和软盘模式之间的对偶对应，在无序颗粒固体的力空间中推导有效哈密顿量。该框架将为探索无序颗粒堆积的力-网系综奠定基础。PI提出利用自应力和软盘模式的双重性来设计具有声子带隙的无序机械超材料。CAREER奖还支持与研究紧密结合的教育活动。其目标是增加第一次上物理课的学生的多样性和保留率，无论是在高中还是大学。PI将与K-12 STEM教育工作者合作，为物理入门课程设计非常规但易于理解的教学模块。这些模块将以生物物理学、流行病学和生物学为基础，同时与导论物理学中教授的基本物理概念建立联系。这些模块与传统的“教科书示例”有很大不同，将为学生提供关于物理概念的适用性和影响的大开眼界的体验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis CAREER award supports theoretical and computational research integrated with education to gain a unified understanding of the physical properties of cellular materials. From honeycombs to foams to biological cells, materials with cellular structures are ubiquitous in nature. To advance understanding of cellular materials, the PI will use an interdisciplinary approach that combines knowledge and techniques from physics, geometry, and biology.Organ surfaces are covered with dense layers of cells, acting as physical barriers. While normally non-migratory, cells can undergo active rearrangements during basic processes such as embryo development, morphogenesis, repair, and remodeling. In these events, the cell layer transitions from a solid-like state to a fluid-like state. This striking transition is traditionally studied in the context of cells on a flat surface. However, most organ surfaces are naturally non-flat, and comprised of curved surfaces such as spheres, saddles, or cylinders. How surface curvature affects cell motion remains largely unknown. To address these questions, the principal investigator will study how cells move collectively on a curved surface and the role of curvature on whether they behave like a solid or a fluid. These investigations will generate predictions that can be tested experimentally in living embryos and lab-cultured tissues.The knowledge gained from biological tissues will serve as an inspiration for the PI to investigate the origin of rigidity in other cellular structures. These include the meshwork of forces in a solid or a mechanical network constructed by randomly connecting springs. The goal is to develop design principles for cellular structures to exhibit unusual mechanical properties and take advantage of them to design functional materials that do not readily occur in nature.This CAREER award also supports educational activities tightly integrated with the research. The goal is to increase diversity and retention of students taking physics classes for the very first time, whether in high school or college. The PI will collaborate with K-12 STEM educators to design unconventional yet accessible teaching modules for introductory physics classes. The modules will be based on biophysics, epidemiology, and biology while drawing connections to the fundamental physical concepts taught in introductory physics. These modules, which differ greatly from conventional "textbook examples", will provide students an eye-opening experience on the applicability and impact of physics concepts.TECHNICAL SUMMARYThis CAREER award supports integrated theoretical and computational research, outreach, and education with the aim to advance the fundamental understanding of the statistical mechanics and collective behavior of cellular materials, including biological tissues, foams, granular packings, and their force networks.In the biological context, the project will investigate the nature of the jamming/unjamming transition in multicellular collectives constrained on a curved surface and elucidate the origin of coherent angular motion that arises as a unique consequence of non-zero Gaussian curvature. In non-biological cellular structures, the PI will investigate the consequence of mechanical dualities. The objective will involve deriving an effective Hamiltonian in the force space for disordered granular solids based on the dual correspondence between self-stress states and floppy modes. The framework will be the basis for exploring the force-network ensemble of disordered grain packings. The PI proposes to leverage the duality of self-stresses and floppy modes to design disordered mechanical metamaterials with phononic bandgaps.This CAREER award also supports educational activities tightly integrated with the research. The goal is to increase diversity and retention of students taking physics classes for the very first time, whether in high school or college. The PI will collaborate with K-12 STEM educators to design unconventional yet accessible teaching modules for introductory physics classes. The modules will be based on biophysics, epidemiology, and biology while drawing connections to the fundamental physical concepts taught in introductory physics. These modules, which differ greatly from conventional "textbook examples", will provide students an eye-opening experience on the applicability and impact of physics concepts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.