Collaborative Research:Fundamental Principles of Swimming in Viscoelastic Media

合作研究：粘弹性介质中游泳的基本原理

• 批准号: 0854108
• 负责人: Thomas Powers
• 金额: $ 52.5万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0854108&HistoricalAwards=false
• 关键词: Collaborative; Research; Fundamental; Principles; Swimming

Powers0854108Cell movements play a central role in a host of biological processes, such as fertilization, bacterial infection, and transport of mucus and fluid in the body. The complex fluids that motile cells encounter are laden with polymers. When deformed by a swimming cell, the polymers stretch, leading to an elastic resistance in addition to the viscous resistance of the fluid. The microstructure of biological materials is often anisotropic as well. The goal of this research is to use theory and experimental models to establish the fundamental principles of swimming in viscoelastic media such as mucus and biofilms. To study swimming mechanics in a controlled environment, the PIs will develop a series of table-top macroscopic scale experiments. These experiments will determine how swimming speed depends on viscoelastic properties for a swimmer with a prescribed stroke, how viscoelastic forces can alter the shape of a beating filament, and the role of viscoelasticity in the hydrodynamic synchronization of beating cilia. The PIs will develop new theories for these phenomena, and also study how non-Newtonian effects change the hydrodynamic interactions between nearby swimmers and boundaries, and the nature of the collective motion of dense populations of swimmers. The basic hydrodynamic theory for microorganisms swimming in a Newtonian liquid such as water has been largely established. Nevertheless, the field continues to be very active since many issues such as hydrodynamic interactions between cells, synchronized ciliary beating, and the actuation of flagella are only partially understood. The natural environments of microorganisms are predominantly non-Newtonian, and every basic element of the theory must be considered anew. Our work will also establish the design principles required to build artificial microswimmers capable of negotiating viscoelastic as well as viscous fluids. The PIs will work with the K-12 Teacher Training program within the Brown MRSEC outreach program to develop new demonstrations of cell motility. The PIs will continue to build on their successful history of recruiting under-represented groups. Finally, the fundamental principles of this work have the potential to impact applications such human fertility, the treatment of bacterial infections and diseases such as cystic fibrosis, and the artificial insemination of livestock.

细胞运动在许多生物过程中起着核心作用，如受精、细菌感染以及体内粘液和液体的运输。运动细胞遇到的复杂液体充满了聚合物。当通过游泳池变形时，聚合物拉伸，导致除了流体的粘性阻力之外的弹性阻力。生物材料的微观结构通常也是各向异性的。 本研究的目的是使用理论和实验模型来建立在粘弹性介质（如粘液和生物膜）中游泳的基本原理。 为了在受控环境中研究游泳力学，PI将开发一系列桌面宏观尺度实验。这些实验将确定如何游泳速度取决于粘弹性与规定的中风，如何粘弹性力可以改变形状的跳动丝，和粘弹性的作用，在流体动力学同步的跳动纤毛的游泳者。PI将为这些现象开发新的理论，并研究非牛顿效应如何改变附近游泳者和边界之间的流体动力学相互作用，以及密集游泳者群体集体运动的性质。微生物在牛顿流体如水中游动的基本流体动力学理论已基本建立。尽管如此，该领域仍然非常活跃，因为许多问题，如细胞之间的流体动力学相互作用，同步纤毛跳动，鞭毛的驱动只有部分了解。微生物的自然环境主要是非牛顿的，理论的每一个基本要素都必须重新考虑。我们的工作也将建立所需的设计原则，以建立能够谈判粘弹性以及粘性流体的人工微泳者。PI将与布朗MRSEC外展计划中的K-12教师培训计划合作，开发细胞运动的新演示。PI将继续在其招募代表性不足群体的成功历史的基础上再接再厉。最后，这项工作的基本原理有可能影响人类生育力，治疗细菌感染和囊性纤维化等疾病以及牲畜人工授精等应用。