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.

活性物质是软物质科学中最令人兴奋的前沿领域之一。与典型的流体不同，活性流体不处于平衡状态。 相反，它们在局部消耗能量，将这种能量转化为内部流动和自发混合。在这个项目中，将使用由微管和驱动蛋白（细胞中发现的生物分子）组成的流体来研究活性流体中的质量传输和混沌混合。由于耦合驱动蛋白分子马达，密集排列的微管以受控的速率彼此反向平行滑动。这项工作的一个令人兴奋的成果可能是一类新的自混合活性溶剂的开发。这样的溶剂可能会彻底改变我们对质量传递和化学反应动力学的理解。目前的提议涉及比标准溶剂大得多的长度尺度，因此将作为这些新想法的实验模型，有助于建立控制活性物质行为的基本定律。由于生物细胞的内容物是高度复杂的活性物质，远离平衡，这项工作有望对活性物质在生物学中的作用产生新的见解。一个拟议中的Telluride关于活性流体传输的研讨会将有助于将液晶、生物流体和非线性动力学等相对不同的领域汇集在一起。 这项工作将对加州大学默塞德分校产生重大的教育影响，这是一所位于加州最贫困地区的新大学。这项研究将为几篇本科论文提供基础，PI将利用这项工作的见解将尖端材料引入他们的研究生和本科教学。这个项目的重点是运输和混合在一个生物启发的可扩展的活性染料。由于驱动蛋白分子马达，密集包装的微管以受控的速率彼此反向平行滑动，并且由此产生的混沌平流将在不同的长度尺度上测量，使用粒子跟踪，粒子图像测速和标记示踪剂的荧光成像的实验工具。实验数据将使用非线性和拓扑动力学的工具进行理论解释，从而在一个独特的合作努力中合并混沌平流和液晶领域。拓扑熵将在这项研究中发挥核心的统一作用。拓扑熵在混沌平流的研究中是众所周知的，但迄今为止在活动向列相的研究中被忽视了。具体目标是：（1）利用粒子追踪和速度重构技术，结合非线性动力学的工具，测量了主动湍流混合的拓扑熵，（2）测量了宏观尺度上的主动湍流的有效扩散率，并通过混沌平流增强了有效扩散率;研究分子尺度动力学、中尺度混合该奖项反映了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

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.

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.

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.