Hydrodynamic Instabilities, Pattern Formation and Topology in Active

活性液晶代表了活性物质的原型，为组织生物过程和受生物启发的材料提供了一个框架，范围从细菌群和生长菌落到细胞骨架。利用液晶的现象学已经确定了活性物质的某些一般特征，如自发流动、流体动力不稳定性和主动湍流。这一领域继续为非平衡物理提供基本问题，在生物学领域具有潜在的广泛应用。在大多数情况下，现有的工作集中在向列相或极性相上，也主要集中在二维特征上。手性在自然界中无处不在，既存在于生物结构中，也存在于制造它们的细丝和生物聚合物的悬浮液中。例如，DNA在溶液中形成手性液晶相。然而，主动应力对手性材料和结构的影响迄今尚未得到研究。该项目将利用胆甾液晶的框架和现象学来发展手性活性物质的表征和理解。我们将扩展并继续我的小组在活性胆固醇的基本流体动力学不稳定性方面的初步工作，特别是进行完整的三维分析，以解释边界条件或限制的影响，并研究不同被动胆固醇结构的稳定性。例如，确定衬底上薄膜的形态或活性胆固醇滴的形态是很自然的

Active liquid crystals have come to represent an archetype for active matter, offering a framework for organising ideas about biological processes and biologically inspired materials, ranging from bacterial swarms and growing colonies to the cell cytoskeleton. Certain generic traits for active materials, such as spontaneous flows, hydrodynamic instabilities and active turbulence, have been identified using the phenomenology of liquid crystals. This area continues to provide fundamental questions in non-equilibrium physics, with potentially widespread applications across biology. For the most part, existing work has focused on nematic or polar phases, and also largely on a two-dimensional characterisation. Chirality is ubiquitous in nature, appearing both in biological structures and in suspen- sions of the filaments and biopolymers that they are made from. For instance, DNA forms chiral liquid crystalline phases in solution. However, the effects of active stresses on chiral materials and structures have so far not been studied.This project will develop the characterisation and understanding of chiral active materials using the framework and phenomenology of cholesteric liquid crystals. We will extend and continue initial work in my group on the fundamental hydrodynamic instabilities in active cholesterics, in particular to a full three-dimensional analysis, to account for the influence of boundary conditions, or confinement, and to study the stability of different passive cholesteric textures. For instance, it would be natural to determine the morphology of thin films on substrates, or of active cholesteric droplets