Self-mixing Active Fluids

自混合活性液体

• 批准号: 1808926
• 负责人: Linda Hirst
• 金额: $ 62.48万
• 依托单位: University of California - Merced
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808926&HistoricalAwards=false
• 关键词: Self; mixing; Active; Fluids

Active matter is one of the most exciting frontiers in soft matter science. Unlike typical fluids, active fluids are not in equilibrium. Instead, they consume energy locally, translating this energy into internal flows and spontaneous mixing. In this project, mass transport and chaotic mixing in active fluids will be investigated using a fluid consisting of microtubules and kinesin, biological molecules found in the cell. Densely packed microtubules slide antiparallel to each other at a controlled rate due to coupled kinesin molecular motors. An exciting outcome of this work could be the development of a new class of self-mixing active solvents. Such a solvent could revolutionize our understanding of the kinetics of mass transport and chemical reactions. The present proposal concerns much larger length scales than that of standard solvents and will thus serve as an experimental model for these new ideas, helping to establish fundamental laws that govern the behavior of active matter. Since the contents of biological cells are highly complex active materials, far from equilibrium, this work is expected to yield new insights into the role of active materials in biology. A proposed Telluride workshop on transport in active fluids will help to bring together the relatively disparate fields of liquid crystals, biological fluids and nonlinear dynamics. This work will have a significant educational impact at UC Merced, a new university in one of California's most socio-economically disadvantaged areas. This research will provide the basis for several undergraduate theses and the PIs will use insights from this work to introduce cutting edge materials to their graduate and undergraduate teaching. This project focuses on transport and mixing in a biologically inspired extensile active nematic. Densely packed microtubules slide antiparallel to each other at a controlled rate due to kinesin molecular motors and the resulting chaotic advection will be measured on different length scales, using the experimental tools of particle tracking, particle image velocimetry, and fluorescence imaging of labeled tracers. Experimental data will be theoretically interpreted using the tools of nonlinear and topological dynamics, thereby merging the fields of chaotic advection and liquid crystals in a unique collaborative effort. Topological entropy will play a central, unifying role in this study. Topological entropy is well known in studies of chaotic advection, but has been thus far overlooked in studies of active nematics. Specific aims are to: 1) use bead tracking and velocity reconstruction, together with tools from nonlinear dynamics, to measure the topological entropy of active nematic mixing; 2) measure the effective diffusivity, enhanced by chaotic advection, of the active nematic on the macroscale; and 3) investigate correlations between molecular-scale dynamics, mesoscale mixing, and macroscale diffusion by varying system parameters.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.

活跃物质是软物质科学中最令人兴奋的边界之一。与典型的流体不同，活性流体不处于平衡状态。 相反，他们在本地消耗能量，将这种能量转化为内部流和自发混合。在该项目中，将使用由微管和动力蛋白组成的流体研究活性液中的大规模传输和混合混合，该液在细胞中发现的生物分子。密集的堆积的微管以耦合的驱动蛋白分子电动机的控制速率彼此隔开。这项工作的令人兴奋的结果可能是开发新的一种自我混合活跃溶剂。这样的溶剂可以彻底改变我们对大规模运输和化学反应动力学的理解。本提案的长度比标准溶剂要大得多，因此将作为这些新想法的实验模型，有助于建立控制主动物质行为的基本定律。由于生物细胞的含量是高度复杂的活性材料，远非平衡，因此这项工作有望产生有关活性材料在生物学中的作用的新见解。提出的有关活性流体运输的胎胎研讨会将有助于将液晶，生物流体和非线性动力学的相对不同的领域汇总在一起。 这项工作将对加利福尼亚州最受社会经济最弱势的地区之一的新大学加州大学默塞德（UC Merced）产生重大的教育影响。这项研究将为几个本科论文提供基础，PIS将使用这项工作的见解向他们的研究生和本科教学引入尖端材料。该项目侧重于在生物学启发的广泛主动列中进行运输和混合。密集填充的微管以受控的速率彼此隔离，这是由于动力蛋白分子电机的控制速率，并且将使用粒子跟踪的实验工具，粒子图像速度测定层和标记的示踪剂的荧光成像，在不同的长度尺度上测量所得的混沌对流。理论上将使用非线性和拓扑动态的工具对实验数据进行解释，从而以独特的协作努力将混乱的对流和液晶的领域融合在一起。拓扑熵将在这项研究中发挥核心，统一的作用。拓扑熵在混乱的对流研究中是众所周知的，但到目前为止，在主动神灵的研究中被忽略了。具体目的是：1）使用珠子跟踪和速度重建以及非线性动力学的工具，以测量主动列米混合的拓扑熵； 2）测量宏观上的主动命名的混乱对流增强的有效扩散率； 3）研究分子尺度动力学，中尺度混合和通过不同的系统参数扩散之间的相关性。该奖项反映了NSF的法定任务，并被认为值得通过基金会的知识优点和更广泛的影响标准通过评估来进行评估。

项目成果

Topological chaos in active nematics

• DOI: 10.1038/s41567-019-0600-y
• 发表时间: 2019-08
• 期刊: Nature Physics
• 影响因子: 19.6
• 作者: Amanda J. Tan;Eric Roberts;Spencer A. Smith;Ulyses Alvarado Olvera;Jorge Arteaga;Sam Fortini;K. Mitchell;L. Hirst

Using Curved Fluid Boundaries to Confine Active Nematic Flows

• DOI: 10.3389/fphy.2022.880941
• 发表时间: 2022-04-27
• 期刊: FRONTIERS IN PHYSICS
• 影响因子: 3.1
• 作者: Khaladj, Dimitrius A.;Hirst, Linda S.
• 通讯作者: Hirst, Linda S.

Using epoxy-based lithography to probe confinement effects on active nematics

使用环氧基光刻来探测对活性向列相的限制效应

• DOI: 10.1117/12.2528602
• 发表时间: 2019
• 期刊: Liquid Crystals XXIII
• 作者: Khaladj, Dimitrius A.;Tan, Amanda J.;Hirst, Linda S.
• 通讯作者: Hirst, Linda S.

Submersed micropatterned structures control active nematic flow, topology, and concentration

• DOI: 10.1073/pnas.2106038118
• 发表时间: 2021-09-21
• 期刊: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• 影响因子: 11.1
• 作者: Thijssen, Kristian;Khaladj, Dimitrius A.;Shendruk, Tyler N.
• 通讯作者: Shendruk, Tyler N.

Membrane mediated motor kinetics in microtubule gliding assays

• DOI: 10.1038/s41598-019-45847-z
• 发表时间: 2019-07-03
• 期刊: SCIENTIFIC REPORTS
• 影响因子: 4.6
• 作者: Lopes, Joseph;Quint, David A.;Hirst, Linda S.
• 通讯作者: Hirst, Linda S.