Developing quantitative continuum theories of composite active fluids

发展复合活性流体的定量连续理论

• 批准号: 2202353
• 负责人: Aparna Baskaran
• 金额: $ 33.38万
• 依托单位: Brandeis University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2202353&HistoricalAwards=false
• 关键词: Developing; quantitative; continuum; theories; composite

NONTECHNICAL SUMMARYThis award supports theoretical, computational, and data-intensive research to develop a theory to describe flow phenomena in biological and other fluids that contain self-powered elements. Flow phenomena in nature and in engineered systems are typically driven by external forces such as gravity and pressure gradients. Continuum mechanics is the mathematical language that allows us to describe such flows and hence predict and design them. In biological systems, such as the cell cytoskeleton, flow phenomena are generated by internal driving, powered by proteins and other biochemical machines that consume chemical energy. Continuum mechanical descriptions have been developed and applied to such internally driven biological fluids in recent years with great success. So far, efforts have centered around single-component descriptions of these systems. In actuality, these are multicomponent systems. Developing multicomponent continuum theories for internally driven fluids requires overcoming several technical challenges. This project uses multi-scale theory coupled with data driven techniques to address these technical challenges and hence develop models for multi-component biological fluids. This project is a step toward understanding physical mechanisms that lead to function in natural and synthetic biological systems. From a practical perspective, designing and controlling internally driven fluids is key to engineering rapidly reconfigurable life-like materials, with applications in fields as diverse as robotics, microfluidics, and adaptive optics. In addition to the science outcomes, the research is integrated with education and outreach initiatives including : (i) content for an advanced undergraduate course on soft materials theory – this fills a need in the education of undergraduate students to undertake interdisciplinary research at the interface of physics and biology and (ii) Diversity, Education and Inclusion initiatives implemented, tested and benchmarked within the Brandeis community that can be exported as models shared widely with the academic community. TECHNICAL SUMMARY This award supports theoretical, computational, and data-intensive research to develop a theoretical framework for building predictive continuum descriptions of composite active fluids. Active fluids are composed of microscopic entities that consume energy and exert forces. This paradigm includes diverse systems from bacterial suspensions to cytoskeletal filaments propelled by molecular motors and synthetic diffusophoretic colloids. Continuum descriptions of the dynamics of these fluids have been powerful in identifying transferable concepts that allow us to understand, control, and even predictively design active fluids. Research to date has focused on single component fluid dynamic descriptions of active materials. But experimental phenomenology clearly shows the need for multi-component descriptions that allow for density gradients in different components. Building macroscopic theories of multi-component systems is challenging even in the context of traditional equilibrating fluids. One needs to invoke considerations of reciprocity and entropy production to determine relationships between different fluxes in the dynamics of conserved quantities. Active fluids, being inherently out of equilibrium are liberated from these constraints. This project addresses these challenges by developing a multi-pronged approach that integrates data driven model development with the standard techniques of soft materials physics. On the one hand, phenomenological continuum mechanics will be combined with systematic nonequilibrium statistical mechanics to identify possible mechanisms at play in determining the emergent behavior in composite active fluids. On the other hand, a complementary data-driven approach is developed, that leverages experimental data from in-vitro cytoskeletal suspension experiments to guide model discovery.This project is aimed to yield fundamental theoretical insights into non-reciprocal cross diffusion processes and their role in emergent behavior in active composite fluids. This effort is a first step in understanding physical mechanisms that lead to function in biological systems. From a practical perspective, designing and controlling active stresses is key to engineering rapidly reconfigurable life-like materials, with applications in fields as diverse as robotics, microfluidics and adaptive optics. The theoretical framework developed in this project will advance our ability to engineer active stress in materials. Integrated with the research effort, this project will produce impact in the community and in physics education through the following initiatives: (i) The development and distribution of content for an advanced undergraduate course on soft materials theory – this fills a need in the education of our undergraduates to undertake interdisciplinary research at the interface of physics and biology. (ii) Outreach initiatives in the Waltham community and beyond – this allows us to work with URM students and reach students in developing countries to expose them to ongoing work in soft materials and biophysics. (iii) Diversity, Education and Inclusion initiatives within the Brandeis community that will serve as a model that can be shared with a wider audience for implementation at other institutions.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.

非技术总结该奖项支持理论，计算和数据密集型研究，以开发一种理论来描述包含自供电元素的生物和其他流体中的流动现象。自然界和工程系统中的流动现象通常由诸如重力和压力梯度的外力驱动。连续介质力学是一种数学语言，使我们能够描述这种流动，从而预测和设计它们。在生物系统中，如细胞骨架，流动现象是由内部驱动产生的，由蛋白质和其他消耗化学能的生化机器提供动力。近年来，连续统力学描述已经被开发并应用于这种内部驱动的生物流体，并取得了巨大的成功。到目前为止，努力集中在这些系统的单组件描述。实际上，这些是多组分系统。开发内部驱动流体的多组分连续体理论需要克服几个技术挑战。该项目使用多尺度理论结合数据驱动技术来解决这些技术挑战，从而开发多组分生物流体模型。该项目是理解导致自然和合成生物系统功能的物理机制的一步。从实践的角度来看，设计和控制内部驱动的流体是工程快速可重构的类生命材料的关键，其应用领域广泛，如机器人，微流体和自适应光学。除了科学成果外，研究还与教育和宣传活动相结合，包括：（i）关于软材料理论的高级本科课程的内容-这满足了本科生在物理学和生物学交叉领域进行跨学科研究的教育需要，以及（ii）实施多样性、教育和包容性倡议，在Brandeis社区内进行测试和基准测试，可以作为模型与学术界广泛共享。该奖项支持理论，计算和数据密集型研究，以开发用于构建复合活性流体预测连续描述的理论框架。活性流体由消耗能量并施加力的微观实体组成。这一范例包括从细菌悬浮液到由分子马达和合成的扩散泳胶体推动的细胞骨架丝的各种系统。这些流体动力学的连续描述在识别可转移的概念方面是强大的，这些概念使我们能够理解，控制，甚至预测性地设计活性流体。 迄今为止的研究主要集中在活性材料的单组分流体动力学描述上。但实验现象学清楚地表明，需要多组分描述，允许不同组分的密度梯度。即使在传统的平衡流体的背景下，建立多组分系统的宏观理论也是具有挑战性的。我们需要考虑互易性和熵的产生来确定守恒量动力学中不同通量之间的关系。活性流体，本质上是不平衡的，从这些约束中解放出来。该项目通过开发一种多管齐下的方法来解决这些挑战，该方法将数据驱动的模型开发与软材料物理的标准技术相结合。一方面，唯象连续介质力学将与系统的非平衡统计力学相结合，以确定可能的机制，在确定复合活性流体的涌现行为。另一方面，一个互补的数据驱动的方法，利用体外细胞骨架悬浮实验的实验数据来指导模型发现，该项目的目的是产生非互易交叉扩散过程及其在活性复合流体中的涌现行为中的作用的基本理论见解。这项工作是理解导致生物系统功能的物理机制的第一步。从实践的角度来看，设计和控制主动应力是工程快速可重构的类生命材料的关键，其应用领域广泛，如机器人，微流体和自适应光学。在这个项目中开发的理论框架将提高我们在材料中设计主动应力的能力。与研究工作相结合，该项目将通过以下举措对社区和物理教育产生影响：（i）开发和分发软材料理论高级本科课程的内容-这满足了我们本科生教育的需要，在物理学和生物学的界面上进行跨学科研究。(ii)在沃尔瑟姆社区和超越-这使我们能够与URM的学生和接触发展中国家的学生，让他们接触到正在进行的工作在软材料和生物物理学的推广计划。(iii)该奖项反映了NSF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。

项目成果

From disks to channels: dynamics of active nematics confined to an annulus

从圆盘到通道：局限于环面的活性向列动力学

• DOI: 10.1039/d3sm00477e
• 发表时间: 2023
• 期刊: Soft Matter
• 影响因子: 3.4
• 作者: Joshi, Chaitanya;Zarei, Zahra;Norton, Michael M.;Fraden, Seth;Baskaran, Aparna;Hagan, Michael F.
• 通讯作者: Hagan, Michael F.