有限多孔介质诱导活性哑铃的聚集行为  

Finite porous medium induced aggregation behavior of active dumbbells

作　　者：金燕 石子璇 金奕扬 田文得 张天辉 陈康 Jin Yan;Shi Zi-Xuan;Jin Yi-Yang;Tian Wen-De;Zhang Tian-Hui;Chen Kang(Center for Soft Condensed Matter Physics&Interdisciplinary Research,School of Physical Science and Technology,Soochow University,Suzhou 215006,China)

机构地区：[1]苏州大学物理科学与技术学院,软凝聚态物理及交叉研究中心,苏州215006

出　　处：《物理学报》2024年第16期36-44,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:21774091,21674078,11974255)资助的课题.

摘　　要：自然界的许多活性物质都处在复杂的环境中,例如动物群体穿过丛林、微生物在土壤中迁移、细菌被设计用于感知肿瘤的多孔环境等.活性物质在复杂环境中的行为是一个值得探究的课题,在生物物理、医疗工程、工业领域具有可观的应用意义.本文用活性哑铃代表细菌等具有形状各向异性的活性物质,采用郎之万动力学模拟,研究它们渗透有限多孔介质的行为.研究发现在低温和适当的活性力下,活性哑铃能在介质内外聚集并形成4种稳定的聚集结构.4种聚集结构分别是中空巨聚集、介质内中空聚集、密实巨聚集、介质内密实聚集.定向运动的持久性决定了活性哑铃的聚集程度.4种聚集结构的密度、极性序参量、热力学温度在介质内外的分布有明显的区别.本研究结果有助于进一步理解活性物质在复杂环境中的生命活动,为微流器件的设计、药物的输运等医学操作提供新的思路.Many active substances in nature are in complex environments,such as animal populations passing through the jungles,microorganisms migrating in the soil,and bacteria designed to sense the porous environment of tumors.The behavior of active substances in complex environments is a subject worth exploring,because they have great application significance in biophysics,medical engineering,and industrial fields.In this work,we use active dumbbells to represent bacteria and other active substances with shape anisotropy,and use Langevin dynamics simulation to study their permeation behaviors in finite porous media.We find that under low temperature and appropriate activity,active dumbbells can aggregate inside and outside the medium and form four stable aggregation structures,they being hollow giant aggregation,hollow aggregation in medium,dense giant aggregation,and dense aggregation in medium.The aggregation is caused by the small space of the medium region,and the geometric trap is easily formed when the active dumbbells meet in the medium.Unlike motility-induced phase separation,the formation of such an aggregation relies on the assistance of obstacles.The persistence of directional motion determines the degree of aggregation of active dumbbells.There are significant differences among the four aggregation structures in density distribution,polar order parameter,and thermodynamic temperature inside and outside the medium.Under certain conditions,the disorder of medium arrangement can promote the aggregation behavior of active dumbbells,and the increase of lattice constant makes it easier for active dumbbells to form dense aggregation.Our research findings contribute to a more in-depth understanding of the life activities of active substances in complex environments,thus providing new ideas for designing microfluidic devices,drug delivery and other medical operations.

关 键 词：活性物质 多孔介质 郎之万动力学模拟 

分 类 号：O469[理学—凝聚态物理]