Long, Coiled, Actuated: Complex Flagella Moving Through Heterogeneous Fluid Environments

长的、卷曲的、驱动的：复杂的鞭毛在异质流体环境中移动

• 批准号: 1951707
• 负责人: Lisa Fauci
• 金额: $ 36万
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1951707&HistoricalAwards=false
• 关键词: Long; Coiled; Actuated; Complex; Flagella

The study of how natural and robotic microorganisms propel themselves in a fluid through the beating of flagella has enjoyed much success through advances in imaging technologies, computational methods, microfluidic devices, and materials science. However, in biological systems, rarely does an undulating flagellum beat freely, but may beat in close proximity to (or through) passive elastic structures such as mucosal strands embedded in the fluid environment or walls of tubular ducts. This project will investigate the motility of microorganisms through fluids with suspended polymeric networks where the gaps between polymer filaments are comparable to the size of the organism. The study is relevant to mammalian sperm-egg penetration and spirochete motility through mucosal tissues. The project will also investigate the journey of insect sperm through narrow sperm storage organs in the female reproductive tract. These systems require the development of novel mathematical models and computational methods that move beyond simple representations of sperm flagella, that allow remodeling of discrete viscoelastic networks, and that capture the geometry of confining structures. The project includes training of a postdoctoral researcher, graduate students, and undergraduates through involvement in the research. The mechanics of a compliant, viscoelastic network embedded in a viscous fluid and the motility of long, actuated fibers moving in confined environments present rich systems in elastohydrodyamics. The project will leverage the method of regularized Stokeslets and recent extensions of it. This methodology will be further advanced through deriving kernels for regularized flow inside a sphere. By choosing a discrete network rather than a continuum description of a non-Newtonian fluid, a heterogeneous environment is easily represented. For instance, the power required for an organism to first penetrate the viscoelastic network (as in mammalian fertilization) and how its form evolves as it moves through these regions can be studied. In particular, the energetics of the Lyme disease spirochete as it migrates through such a viscoelastic network will be investigated. In addition, the dynamics of insect sperm motility in the female reproductive tract will be modeled. Their extreme length and their ability to move into confined spaces present mathematical and computational challenges. The project will use recent advances in modeling the shape deformations and buckling of long, flexible fibers in background flows, coupled with modeling of actuated flagella, to investigate this system.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.

关于自然和机器人微生物如何通过鞭毛的殴打使自己在液体中如何推动自己的研究通过成像技术，计算方法，微流体设备和材料科学取得了很大的成功。但是，在生物系统中，很少会自由地进行起伏的鞭毛跳动，但可能与被动弹性结构（例如嵌入流体环境或管状管道壁）的被动弹性结构（或通过）被动弹性结构非常接近。该项目将通过具有悬浮的聚合物网络的流体来研究微生物的运动，其中聚合物丝之间的间隙与生物体的大小相当。该研究与哺乳动物的精子渗透和通过粘膜组织的螺旋体运动有关。该项目还将通过雌性生殖道中的狭窄的精子储存器官来研究昆虫精子的旅程。这些系统需要开发新型的数学模型和计算方法，这些模型超出了精子鞭毛的简单表示，从而可以重塑离散的粘弹性网络，并捕获限制结构的几何形状。该项目包括通过参与研究的博士后研究人员，研究生和本科生的培训。一个合规，粘弹性网络的力学嵌入在粘性流体中，并且在密闭环境中移动的长肌动纤维的运动性呈现出富含弹性的水素化学的富含系统。该项目将利用正规化的Stokeslet和最近扩展的方法。通过得出球体内的正则流动的内核，该方法将进一步发展。通过选择一个离散网络而不是对非牛顿流体的连续描述，可以很容易地表示异质环境。例如，有机体首先穿透粘弹性网络所需的功率（如哺乳动物的施肥）以及其形式如何在通过这些区域移动而变化。特别是，将研究莱姆病螺旋体的能量学通过这种粘弹性网络迁移。此外，将建模雌性生殖道中昆虫精子运动的动力学。它们的极端长度以及进入狭窄空间的能力提出了数学和计算挑战。该项目将在对背景流中长而柔软的纤维的形状变形和屈曲以及驱动鞭毛的建模进行建模方面使用最新的进步，以调查该系统。该奖项反映了NSF的法定任务，并被视为值得通过使用评估的支持。基金会的智力优点和更广泛的影响审查标准。

项目成果

Performance of a Helical Microswimmer Traversing a Discrete Viscoelastic Network with Dynamic Remodeling

• DOI: 10.3390/fluids7080257
• 发表时间: 2022-07
• 期刊: Fluids
• 影响因子: 1.9
• 作者: Rudi Schuech;R. Cortez;L. Fauci

The Role of the Double-Layer Potential in Regularised Stokeslet Models of Self-Propulsion

双层势在正则化斯托克斯莱特自推进模型中的作用

• DOI: 10.3390/fluids6110411
• 发表时间: 2021
• 期刊: Fluids
• 影响因子: 1.9
• 作者: Smith, David J.;Gallagher, Meurig T.;Schuech, Rudi;Montenegro-Johnson, Thomas D.
• 通讯作者: Montenegro-Johnson, Thomas D.