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

拟议的项目是在Belousov-Zhabotinsky（BZ）反应中形成图案的实验研究，分散在AOT微乳液介质中：BZ-AOT系统。在BZ反应中，化学波和图案是通过耦合自催化和扩散产生的，自催化是一个加速关键产物形成速率的过程，扩散是分子在流体中移动的过程。在微乳液介质中，BZ反应的反应物主要存在于纳米尺寸的水滴中，其被表面活性剂（AOT）分子包围，并且悬浮在油中。所产生的图案的类型可以通过控制油中水滴的浓度和大小来调整。在所展示的丰富多样的图案中，观察到了图灵结构，这些图案在其他化学系统中是以前未知的。艾伦·图灵在1952年提出了这种重要的模式，即产生驻波的模式，作为支撑生物形态发生的机制，生物形态发生是生物体发展形式和结构的过程。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。该技术基于核磁共振（NMR），是非侵入性的，可以提供丰富的化学和物理信息。NMR信号是通过使用射频脉冲使自旋核（即1H）从其平衡位置偏转而产生的。图像是通过施加磁场梯度产生的，磁场梯度可以通过原子核的自旋频率在空间上定位原子核，而自旋频率取决于位置。图像对比度是由核密度或弛豫时间的差异产生的。BZ-AOT系统利用水分子弛豫时间的差异进行成像，通过MRI首次在BZ-AOT系统中观察到三维图像。重要的是，有机会观察化学系统中3D图灵模式的第一个实验示例。MRI还将用于探测微乳液介质的结构和动力学，并更好地了解它如何影响图案的形成和发展。该系统中形成的图案的多样性和复杂性与BZ反应中关键分子的扩散系数的差异有关。这些将使用MRI实验进行测量，并测试模式选择和发展之间的关系。在这个系统中研究图案形成的动机不仅来自于更好地理解化学系统中图案形成的能力，而且还来自于其应用于解开支撑生物波和图案形成的机制。

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.