RHEOLOGY, ENTROPY PRODUCTION AND RATCHETING OF DEFORMABLE ACTIVE SYSTEMS

可变形主动系统的流变学、熵产生和棘轮

• 批准号: 2321925
• 负责人: Angelo Cacciuto
• 金额: $ 34.49万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2321925&HistoricalAwards=false
• 关键词: RHEOLOGY; ENTROPY; PRODUCTION; RATCHETING; DEFORMABLE

NON-TECHNICAL SUMMARY This award supports theoretical research and education that aims at understanding three important aspects of active materials that are currently unexplored. Active matter is an exciting new field in materials engineering and has come into prominence over the last decade. This occurred because of the development of micro-particles capable of self-propulsion. One can think of these particles as synthetic analogs of bacteria whose shape, surface chemistry and velocity can be designed in a lab. There are several fundamental questions that need to be addressed in this field and that offer new opportunities for the development of the next generation of smart materials. What is the elastic response to external stimuli of materials formed by active particles? This is an important problem that can improve our understanding of the mechanical properties of a large number of materials, from biofilms to epithelial tissue. Another unexplored issue concerns the behavior of active surfaces. Unlike synthetic vesicles, the motion of a biological cell is completely determined by complex biochemical reactions. This makes their behavior similar to that of active systems. It is therefore important to understand how surfaces/vesicles respond to active forces. For instance, fibroblasts and epithelial cancerous cells can acquire directional motion when confined within rigid, asymmetric micro-channels. The PI will explore to what extent such a behavior can be captured by a much simpler system: a synthetic vesicle loaded with active particles. The goal is to develop simple synthetic analogs of biological cells capable of mimicking their mechanical behavior. Finally, one of the main characteristics of active systems is that they break time-reversal symmetry, i.e. running time backwards on a particle trajectory does take the particle back along the same path from which it came. The degree to which this happens in a system can be quantified by measuring Entropy Production. The team will measure this quantity for a number of active systems and establish a link between spatial gradients in Entropy Production and the degree to which active systems are out of equilibrium and capable of performing work. The outcomes of this research will provide insight into how to design stimuli-responsive materials capable of performing work at the microscale. The numerical tools developed for this project should be transferable to other active systems and will have important implications for a number of biological problems that rely on similar physical mechanisms. The award contributes to the education of undergraduate and graduate students which the PI will recruit to participate in these projects, and they will have first-hand exposure to cutting-edge numerical and statistical methods to model active systems. Furthermore, an outreach plan in collaboration with a number of on-campus organizations such as WISC (Women in Science at Columbia), whose efforts are dedicated to the advancement of women and underrepresented minorities in the sciences, technology, engineering and math, is currently underway, and will be further extended.TECHNICAL SUMMARYThis award supports theoretical research and education that aims at understanding three important issues of active materials that are currently unexplored. The first issue concerns the rheological properties of active condensates. Although a large body of work has been devoted to studying self-assembly, dynamics and the phase behavior of active colloidal particles, limited work has been done to understand the elastic properties of active condensates and their response to external stimuli. This is a fundamental problem that needs to be addressed to better characterize the mechanical properties of these materials. The second issue concerns the interplay between elastic and active forces on fluid vesicles using models that allow for topological transitions. The PI will explore under what conditions rectification can occur when giant unilamellar vesicles are loaded with active particles. While a good amount of work has been done to understand motion rectification of single active particles, not much is known about the transport properties of soft, deformable interfaces activated by self-propelling particles across micro-channels. This is an important problem given that fibroblasts and epithelial cancerous cells can acquire directional motion when confined within asymmetric, periodic channels, and would present a minimal model for the description of such a complex system. The third issue deals with a fundamental question about the very nature of active systems. Although the most intriguing phenomenological behavior of active systems arises, at the most fundamental level, because of time-reversal symmetry breaking, and entropy production is the hallmark signature of lack of equilibrium, a clear relationship between inhomogeneities in local entropy production and the degree to which active systems are out of equilibrium and capable to perform work has not been adequately established. The PI will explore how knowledge of spatial gradients in entropy production can be exploited to maximize the work active systems can perform at the microscale. The outcomes of this research will advance our current knowledge of statistical physics and will provide insight into how to design stimuli-responsive materials capable of performing work at the microscale. The numerical tools developed for this project should be transferable to other active systems and will have important implications for a number of biological problems that rely on similar physical mechanisms. The award contributes to the education of undergraduate and graduate students which the PI will recruit to participate in these projects, and they will have first-hand exposure to cutting-edge numerical and statistical methods to model active systems. Furthermore, an outreach plan in collaboration with a number of on-campus organizations such as WISC (Women in Science at Columbia), whose efforts are dedicated to the advancement of women and underrepresented minorities in the sciences, technology, engineering and math, is currently underway, and will be further extended.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.

非技术摘要该奖项支持理论研究和教育，旨在了解目前尚未探索的活动材料的三个重要方面。 Active Matter是材料工程中令人兴奋的新领域，并且在过去十年中已突出。这是由于能够自我推测的微粒子的发展而发生的。可以将这些颗粒视为细菌的合成类似物，其形状，表面化学和速度可以在实验室中设计。该领域需要解决一些基本问题，这为开发下一代智能材料提供了新的机会。主动颗粒形成的材料外部刺激的弹性反应是什么？这是一个重要的问题，可以提高我们对从生物膜到上皮组织的大量材料的机械性能的理解。另一个未开发的问题涉及主动表面的行为。与合成囊泡不同，生物细胞的运动完全由复杂的生化反应确定。这使得它们的行为类似于活动系统的行为。因此，重要的是要了解表面/囊泡如何响应活性力。例如，当限制在刚性的不对称微通道内时，成纤维细胞和上皮癌细胞可以获取方向运动。 PI将探索这种行为在多大程度上可以通过更简单的系统捕获：一个带有活性颗粒的合成囊泡。目的是开发能够模仿其机械行为的生物细胞的简单合成类似物。最后，活动系统的主要特征之一是它们打破了时间反转对称性，即粒子轨迹上的逆转时间确实使粒子沿着它出现的相同路径恢复。可以通过测量熵产生来量化系统中发生的程度。该团队将对许多活动系统进行测量此数量，并在熵生产中的空间梯度与活动系统不平衡且能够执行工作的程度之间建立联系。 这项研究的结果将提供有关如何设计能够在微观上进行工作的刺激响应材料的见解。为该项目开发的数值工具应可以转移到其他活动系统中，并将对依赖类似物理机制的许多生物学问题具有重要意义。该奖项为PI将招募参加这些项目的本科生和研究生的教育做出了贡献，他们将对尖端的数值和统计方法进行直接接触，以建模活动系统。此外，与许多校园组织（例如WISC（哥伦比亚科学妇女））合作的宣传计划致力于妇女的进步和科学，技术，工程和数学的科学，技术，工程和数学的少数群体的进步，目前正在进行中，并将进一步扩展。未探索。第一个问题涉及活性冷凝物的流变特性。尽管大量工作已致力于研究自组装，动力学和活性胶体颗粒的相行为，但已经做了有限的工作来了解主动冷凝物的弹性特性及其对外部刺激的反应。这是一个基本问题，需要解决这些材料的机械性能。第二个问题涉及使用允许拓扑跃迁的模型在流体囊泡上的弹性和主动力之间的相互作用。当巨大的Unilamellar囊泡带有活性颗粒时，PI将在哪些条件下进行探索。尽管已经做了大量的工作来了解单个活动粒子的运动矫正，但对于跨微通道的自呈现颗粒激活的软，可变形界面的传输特性并不多。鉴于成纤维细胞和上皮癌细胞可以在不对称，周期性通道内限制时，这是一个重要的问题，并且会呈现一个最小的模型，以描述这种复杂的系统。第三个问题涉及有关活动系统本质的基本问题。尽管有效系统的最吸引人的现象学行为是最基本的，但由于时间逆转对称性的破坏和熵的产生是缺乏平衡的标志性的标志，因此在本地熵产生中不均匀的关系之间存在明确的关系，而在哪些程度上却没有平衡系统，而有能力的工作已经成熟。 PI将探讨如何利用熵生产中空间梯度的知识，以最大程度地利用活动系统可以在微观尺度上执行。 这项研究的结果将促进我们当前对统计物理学的了解，并将提供有关如何设计能够在微观上执行工作的刺激响应材料的见解。为该项目开发的数值工具应可以转移到其他活动系统中，并将对依赖类似物理机制的许多生物学问题具有重要意义。该奖项为PI将招募参加这些项目的本科生和研究生的教育做出了贡献，他们将对尖端的数值和统计方法进行直接接触，以建模活动系统。此外，与许多校园内组织（例如WISC（哥伦比亚的科学妇女））合作的宣传计划致力于妇女的进步和科学，技术，工程和数学的科学，技术，工程和数学中的少数群体的发展，目前正在进行中，并将进一步依靠NSF的基础奖，并将其授予NSF的基础奖励。更广泛的影响审查标准。