Dynamics and Mechanics of Active Matter

活性物质的动力学和力学

• 批准号: 1938187
• 负责人: Cristina Marchetti
• 金额: $ 11.1万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1938187&HistoricalAwards=false
• 关键词: Dynamics; Mechanics; Active; Matter

NON-TECHNICAL SUMMARYThis award supports theoretical research and education in active matter, consisting of assemblies of self-driven entities, such as bird flocks or living cells, that take energy from the environment to produce coordinated motion. The ability to turn energy injected at the molecular scale into organized motion and function at the macroscopic scale is a defining property of living systems. One may then think that such organization must be controlled by complex communication pathways or biochemical signaling. In recent years researchers have, however, engineered a number of synthetic analogues with life-like properties, from microswimmers powered by chemical reactions to swarms of nanobots capable of self-organized behavior, demonstrating the key role of physical interactions in controlling collective behavior. The central goal of the research by the PI and her team is to quantify the conditions under which physical models based on a minimal set of interactions can capture complex organization in both living and engineered systems, and to develop and test such models. The research will provide a new powerful mathematical framework for describing quantitatively emergent phenomena in nature, where large groups exhibit coordinated behaviors that are very different from those of the individuals. Working with experimentalists at Syracuse University and at Princeton University, the PI will employ the active matter paradigm to identify the physical mechanisms that drive the life cycle of the soil-dwelling bacterium Myxococcus xanthus, which is controlled by a continuous feedback loop between collective and individual behavior. The PI and her students will also model the collective behavior of synthetic microswimmers and examine the conditions required for such active particles to drive the assembly and organization of inert particles. This work will pave the way to the engineering of smart materials capable of active-assembly, reconfiguration, and self-healing.The project will have transformative impact across several fields, from physics to biology to engineering, and benefit society in several ways. For instance, by differentiating transformations that are triggered by physical mechanisms as opposed to genetics, the work on M. xanthus will help cut down the vast number of possibilities that must be investigated in routine genetic studies. The research will include opportunities for undergraduates, graduate students and postdoctoral researchers. Its highly interdisciplinary nature will provide broad training at the interface between science and bioengineering, opening up a variety of employment opportunities.TECHNICAL SUMMARYThis award supports theoretical research and education on active matter. This name refers to extended systems composed of many interacting entities that are driven out of equilibrium by energy injected at the microscopic scale, breaking detailed balance. Examples include many living systems, from bird flocks to living cells, and engineered ones, from in vitro biopolymer networks activated by motor proteins to synthetic microswimmers. The PI will use a multipronged approach ranging from agent-based models to continuum phenomenology, and informed by collaborations with experimenters to advance understanding of the organizational principles and mechanics of active matter. The problems addressed are organized around three objectives: (1) using minimal models to formulate the nonequilibrium statistical mechanics of active matter, with specific attention to spatially inhomogeneous behavior induced by confinement; (2) identifying generic properties of active flows in confined geometry by examining the dynamics and emergent behavior of topological defects; and (3) applying the active matter paradigm to elucidate the physical mechanisms that drive the complex life cycle of Myxococcus xanthus. The work on self-propelled particle models combines computation and theory to address fundamental questions on the nonequilibrium statistical mechanics of active systems with no microscopic time reversal symmetry. It will specifically examine the extent to which effective descriptions in terms of equilibrium concepts may be possible. The study of the role of topological defects in driving and maintaining self-sustained active flows will provide a powerful framework for characterizing transitions between flow patterns in biofluids in vivo and in vitro, from the cytoplasm to bacterial suspensions. Through the work on M. xanthus, the PI will demonstrate that the active matter paradigm provides a useful way for organizing biological data and isolate the physical mechanisms at play in controlling complex developmental cycles of living systems. The field of active matter brings together communities from a broad range of disciplines and impacts areas ranging from biology to materials design. The proposed work on self-propelled particle models and active assembly will guide the development of new materials with programmed functions. The research on microbial development aims at differentiating transformations that are triggered by physical mechanisms as opposed to genetics and will help cut down the vast number of possibilities that must be investigated in genetic studies. The proposed work will provide broad training for graduate students and postdocs at the interface of physics, engineering and biology and promote the development of a diverse STEM workforce. The PI will continue her engagement with the scientific community by organizing conferences and school that will provide professional development opportunities for young scientists.

非技术摘要该奖项支持活性物质的理论研究和教育，包括自驱动实体的集合，例如鸟群或活细胞，它们从环境中获取能量以产生协调运动。将分子尺度上注入的能量转化为宏观尺度上有组织的运动和功能的能力是生命系统的一个决定性属性。人们可能会认为这种组织必须由复杂的通讯途径或生化信号控制。然而，近年来，研究人员设计了许多具有类似生命特性的合成类似物，从化学反应驱动的微型游泳器到能够自组织行为的纳米机器人群，证明了物理相互作用在控制集体行为中的关键作用。 PI 和她的团队研究的中心目标是量化基于最小交互集的物理模型可以捕获生命系统和工程系统中的复杂组织的条件，并开发和测试此类模型。这项研究将为描述自然界中的定量涌现现象提供一个新的强大的数学框架，在这些现象中，大群体表现出与个体非常不同的协调行为。 PI 将与雪城大学和普林斯顿大学的实验人员合作，采用活性物质范式来确定驱动土壤细菌黄粘球菌生命周期的物理机制，该机制由集体和个体之间的连续反馈循环控制行为。 PI 和她的学生还将模拟合成微型游泳器的集体行为，并检查此类活性粒子驱动惰性粒子组装和组织所需的条件。这项工作将为能够主动组装、重新配置和自我修复的智能材料工程铺平道路。该项目将对从物理到生物学再到工程学的多个领域产生变革性影响，并以多种方式造福社会。例如，通过区分由物理机制而非遗传学引发的转化，对 M. xanthus 的研究将有助于减少常规遗传学研究中必须研究的大量可能性。该研究将为本科生、研究生和博士后研究人员提供机会。其高度跨学科的性质将在科学和生物工程之间提供广泛的培训，开辟各种就业机会。技术摘要该奖项支持活性物质的理论研究和教育。这个名称指的是由许多相互作用的实体组成的扩展系统，这些实体被微观尺度上注入的能量驱使失去平衡，打破了详细的平衡。例子包括许多生命系统，从鸟群到活细胞，以及工程系统，从由运动蛋白激活的体外生物聚合物网络到合成微型游泳器。 PI 将采用多管齐下的方法，从基于主体的模型到连续现象学，并通过与实验者的合作来加深对活性物质的组织原理和机制的理解。所解决的问题围绕三个目标进行组织：（1）使用最小模型来制定活性物质的非平衡统计力学，特别关注由限制引起的空间不均匀行为； （2）通过检查拓扑缺陷的动力学和涌现行为来识别受限几何中活动流的一般属性； (3)应用活性物质范式阐明驱动黄色粘球菌复杂生命周期的物理机制。自驱动粒子模型的工作将计算和理论相结合，以解决不具有微观时间反转对称性的主动系统的非平衡统计力学的基本问题。它将专门研究均衡概念方面的有效描述的可能程度。研究拓扑缺陷在驱动和维持自持主动流中的作用将为表征体内和体外生物流体从细胞质到细菌悬浮液的流动模式之间的转变提供强大的框架。通过对 M. xanthus 的研究，PI 将证明活性物质范式提供了一种有用的方法来组织生物数据并分离在控制生命系统复杂发育周期中起作用的物理机制。 活性物质领域汇集了来自广泛学科的社区，并影响从生物学到材料设计等领域。拟议的自驱动粒子模型和主动组装工作将指导具有编程功能的新材料的开发。对微生物发育的研究旨在区分由物理机制而非遗传学引发的转化，并将有助于减少遗传学研究中必须研究的大量可能性。拟议的工作将为研究生和博士后提供物理、工程和生物学交叉领域的广泛培训，并促进多元化 STEM 劳动力的发展。 PI 将继续与科学界合作，组织会议和学校，为年轻科学家提供专业发展机会。

项目成果

The role of fluid flow in the dynamics of active nematic defects

流体流动在活性向列缺陷动力学中的作用

• DOI: 10.1088/1367-2630/abe8a8
• 发表时间: 2021-03
• 期刊: New Journal of Physics
• 影响因子: 3.3
• 作者: Angheluta, Luiza;Chen, Zhitao;Marchetti, M Cristina;Bowick, Mark J
• 通讯作者: Bowick, Mark J