Active Particles in Colloidal Liquid

在过去的十年里，活性粒子一直是人们非常感兴趣的一个领域。它们的运动和行为不仅为发展非平衡动力学的科学提供了有趣的方法，而且在宏观尺度上也与研究有生命的物体有关，例如鸟类、人群和细菌。尽管一直处于最近胶体研究的前沿，但人们对它们与环境相互作用的细节知之甚少。有许多实验系统的例子，它们不仅表现出主动运动的典型特征，而且还具有自己独特的方面。我打算研究某些活性粒子如何表现，以及如何与胶体棒系统相互作用。拉克伦想要发现更多关于胶体液晶是如何影响活性粒子的，以及液晶是如何受到影响的。为了实现胶体液晶，拉克兰将使用棒状二氧化硅颗粒和FD病毒(一种也呈棒状的病毒)。在二氧化硅系统中，他将使用其他活性二氧化硅颗粒，半包覆在特定的金属中，包括棒状和球状，并使用众所周知的交流电流法或催化分解过氧化氢来推动它们。对于FD病毒液晶，拉克伦打算使用枯草芽孢杆菌的某种菌株。具体地说，胶体的长径比如何影响体系以及液晶块和活性粒子之间的尺寸比将是有趣的。使用不同形状的活性粒子可能会被证明是有趣的，以表明由于活性粒子和被动粒子之间的不匹配而导致的液晶排除体积如何在热力学上改变它们的行为。虽然在以前的工作中，这三个活性体系大多被分类，并观察到分子液晶的存在影响了活性粒子的运动，但在这些情况下，液晶块的大小一直比活性物质的大小小几个数量级。因此，研究液晶块大小与体系活性成分相似的区域是新的，并可能在粒子相互作用中提供新的复杂现象。它希望通过这个项目，不仅进一步了解拉克兰将与之合作的具体系统，而且带来这种知识，并能够将其应用于更广泛的物理现象。例如，细胞是微米或纳米级结构的复杂混合物，可以相互作用形成假液晶，因此研究类似环境中活性粒子的相互作用可以为细胞内运输甚至如何应对病毒或细菌感染提供见解。在这个阶段，活性粒子研究领域已经非常成功地提供了理论模拟和对某些有用现象的预测，我们希望为它们提供一些实验基础。此外，从长远来看，创造具有特定可调功能的设备或材料是可能的。合成活性颗粒最明显的用途是制造靶向给药系统。

Active particles have been an area of great interest in the past decade. Not only do their motions and behaviours provide interesting ways to develop the scienceof non-equilibrium dynamics, they are also relevant in the study of animate objects on the macroscale; such as birds, crowds and bacteria. Despite having been at the front of recent colloidal research very little is know about the specifics of their interactions with their environments. There are many examples of experimental systems that not only express the typical characteristics of active motion, but also have their own peculiar facets. I intend on investigating how certain active particles behave and interact with a system of colloidal rods. Lachlan would like to both discover more about how the colloidal liquid crystals affects the active particles and how in turn the liquid crystal is affected. To achieve a colloidal liquid crystal Lachlan will use rod shaped silica particles and the FD virus (a virus also shaped as a rod). In the silica system he will use other active silica particles half coated in specific metals, both rods and spheres, and propel them using the well known AC current method or with the catalysed decomposition of hydrogen peroxide. For the FD virus liquid crystal Lachlan intend on using a certain strain of the Bacillus subtilis bacteria. Specifically it would be interesting how the aspect ratio of the colloids affect the system as well as the size ratio between the liquid crystal blocks and the active particles. Using different shapes of active particles may prove interesting to show how the excluded volume of the liquid crystal, caused by a miss-match between the active and passive particles, may thermodynamically alter their behaviour. Although in previous work the three active systems have been mostly categorised and cases have been observed where the presence of a molecular liquid crystal has affected the motion of active particles, in these cases the size of the blocks of the liquid crystal has been several orders of magnitude smaller than the size of the active matter. Therefore, investigating the region where the size of the blocks of the liquid crystal is similar to the active component of the system is new and may provide new complex phenomena in the interplay of the particles. It is hoped to achieve, with this project, a furthered understanding of not only the specific system that Lachlan will be working with but to bring that knowledge and be able to apply it to a broader scope of physical phenomena. Cells, for example, are a complex mix of microscale or nanoscale structures which can interact to form pseudo liquid crystals and therefore studying the interaction of active particles in similar environments could give insights to intracellular transport or even how to deal with viral or bacterial infections. At this stage, the field of active particle research has been very successful in providing theoretical simulations and the predictions of certain useful phenomena and we hope to provide some experimental grounding to them. Furthermore, in the long term it may be possible to create devices or materials with specific tunable functions. The most obvious use for synthetic active particles is to make a targeted drug delivery system.