报告题目：Collective phenomena of chiral swimming microorganisms

报告人：上海交通大学张何朋教授
邀请人：蒋凌翔教授

报告时间：2023年7月4日下午14:30

报告地点：华南理工大学五山校区北区科技园2号楼324（腾讯会议：841177807）

前沿软物质学院

华南软物质科学与技术高等研究院

2023年6月29日

报告摘要：

Swimming microorganisms can develop collective phenomena with extended spatiotemporal coherence through interactions between individual cells. In this talk, I will discuss two recent studies on this subject. First, we carried out experiments with marine algae (Effrenium voratum), which swim in circles at the air-liquid interface, and discovered that effective hydrodynamic repulsion between cells in the far field suppresses density fluctuations and generates disordered hyperuniform states under a wide range of density conditions. The second study focused on bacteria (Paenibacillus vortex) colonies growing on agar plates. In this system, while active turbulence without manifest chirality takes place in the bulk, cells self-organize into a wide, clockwise (viewed from the air side) flow all along the typically tortuous centimeter-scale external boundary. We traced the origin of these robust edge flows back to a weak chiral symmetry breaking mechanism at the individual level. Experimental results in both studies were quantitatively reproduced in simple particle models with hydrodynamic and excluded-volume interactions.

报告人简介

张何朋，上海交通大学教授。 2000年本科毕业于复旦大学物理系，2004年在美国纽约城市大学获得博士学位，之后到美国得克萨斯大学奥斯丁分校从事研究工作，2010年加入上海交通大学自然科学研究院和物理与天文学院。关注软物质和生物物理系统中的多尺度、非平衡动力学问题；已在美国科学院院刊、物理评论快报等国际学术刊物发表论文四十余篇，在多个国际学术会议上做邀请报告。工作期间获得基金委杰出青年、优秀青年和教育部青年长江学者等人才项目的支持。