Magnetic Resonance Investigation of Pattern Formation in the Belousov-Zhabotinsky Reaction Dispersed in an AOT Water-in-Oil Microemulsion.

该项目是对分散在AOT微乳液介质BZ-AOT体系中的Belousov-Zhabotinsky （BZ）反应模式形成的实验研究。在BZ反应中，化学波和图案是由偶联自催化产生的，这是一个关键产物形成速度加快的过程，也是分子在流体中运动的扩散过程。在微乳液介质中，BZ反应的反应物主要存在于纳米大小的水滴中，这些水滴被表面活性剂（AOT）分子包围，悬浮在油中。所产生的图案类型可以通过控制油中水滴的浓度和大小来调整。在展示的丰富多样的模式中，观察到一些以前在其他化学系统中未知的图灵结构。这种重要的模式，即产生静止波，是艾伦·图灵在1952年提出的，作为生物形态发生的基础机制，生物形成和结构的过程。其他重要的模式包括虚线和分段螺旋波，它们模仿重要的生物模式，在其他化学系统中尚未观察到。该项目将首次在该系统中使用磁共振成像（MRI）来可视化模式。这项技术基于核磁共振（NMR），是非侵入性的，可以提供丰富的化学和物理信息。核磁共振信号是通过使用射频脉冲使自旋核（即1H）偏离其平衡位置而产生的。利用磁场梯度产生图像，可以根据原子核的自旋频率对其进行空间定位，而自旋频率与位置有关。图像对比度是由原子核密度或弛豫时间的差异产生的。水分子弛豫时间的差异将在BZ-AOT系统的成像模式中得到利用。通过MRI，将首次在BZ-AOT系统中观察到三维（3D）模式。重要的是，有机会在化学系统中观察到第一个三维图灵模式的实验例子。MRI还将用于探测微乳液介质的结构和动力学，更好地了解它如何影响图案的形成和发展。该体系中形成的模式的多样性和复杂性与BZ反应中关键分子扩散系数的差异有关。这些将通过核磁共振实验来测量，并测试模式选择和发展之间的关系。研究该系统模式形成的动机不仅来自于能够更好地理解化学系统中的模式形成，还来自于将其应用于揭示生物波和模式形成的机制。

The proposed project is an experimental investigation of pattern formation in the Belousov-Zhabotinsky (BZ) reaction, dispersed in an AOT microemulsion medium: the BZ-AOT system. In the BZ reaction chemical waves and patterns are produced by coupling autocatalysis, a process whereby the rate of formation of key products accelerates, and diffusion, the process by which molecules move within a fluid. In a microemulsion medium the reactants of the BZ reaction predominantly reside within nanometre-sized water droplets, which are surrounded by surfactant (AOT) molecules, and are suspended in oil. The types of patterns produced can be tuned by controlling the concentration and size of water droplets within the oil. Amongst the rich variety of patterns exhibited, some previously unknown in other chemical systems, Turing structures are observed. This important type of pattern, where stationary waves are produced, has been proposed by Alan Turing in 1952 as the mechanism underpinning biological morphogenesis, the process by which organisms development form and structure. Other important patterns include dashed and segmented spiral waves, which mimic important biological patterns and have not been observed in other chemical systems. This project will use Magnetic Resonance Imaging (MRI) in this system, for the first time, to visualise patterns. This technique is based on Nuclear Magnetic Resonance (NMR), is non-invasive and can provide a wealth of chemical and physical information. The NMR signal is produced, by deflecting spinning nuclei (ie 1H) from their equilibrium positions, using radiofrequency pulses. Images are produce through application of magnetic field gradients, which can spatially locate nuclei by their spinning frequency, which is dependent on position. Image contrast is produced by differences in the density of nuclei or their relaxation time. It is the differences in relaxation time of the water molecules that will be exploited in imaging patterns in the BZ-AOT system.By using MRI, 3-dimensional (3D) patterns will be observed in the BZ-AOT system for the first time. Of significant importance, there is the opportunity to observe the first experimental example of 3D Turing patterns in a chemical system. MRI will also be used to probe the structure and dynamics of the microemulsion medium and better understand how it influences pattern formation and development. The diversity and complexity of patterns formed in this system is linked to differences in the diffusion co-efficients of key molecules in the BZ reaction. These will be measured using MRI experiments and relationships between pattern selection and development will be tested. Motivation for studying pattern formation in this system comes not only from the ability to better understand pattern formation in chemical systems, but also in its application to unravelling mechanisms underpinning biological wave and pattern formation.