Spatiotemporal Dynamics and Collective Behavior in Chemical Systems

西弗吉尼亚大学的Kenneth Showalter获得了理论和计算化学计划的奖项，用于研究化学系统的时空动力学和集体行为。 该奖项的部分共同资金由数学科学部的应用数学计划提供。 在这项工作中，三条主要的调查路线正在进行：（一）粒子状反应扩散波的集体行为;（二）大量振荡珠的同步和动态群体感应行为;（三）自推进催化粒子的集合行为。 在第一个项目中，人口的稳定波分布的光敏Belousov-Zhabotinsky（BZ）介质正在研究在受控的实验室环境中的集体行为的特征。波通过Lennard Jones型势相互作用，不同类型的集体行为的起源，如游行和旋转模式，正在被表征。在第二个项目中，在无催化剂的BZ反应混合物中研究了大量负载催化剂的珠粒。这些研究的重点是研究搅拌悬浮液和时空分布式系统中的同步和动态群体感应行为。第三个项目涉及研究反应物溶液中自推进催化颗粒的相互作用。 二氧化硅球用各种金属或酶涂层制备，例如Pt或辣根过氧化物酶，其催化反应物（例如过氧化氢）的分解。这些粒子的传播行为，然后研究作为粒子密度的函数，以确定导致集体行为的速度的相关性。所有这三条研究线预计将产生新的和重要的信息时空动力学和集体行为的化学系统，并提供深入了解这种行为在生物系统中。 对相互作用的类粒子波的研究将推进时空系统的控制，并将从实验室实验中提供对集体行为的见解。更好地了解同步和动态群体感应机制将获得在大人口的离散振荡器的研究，提供洞察相关的微生物动力学。对相互作用的自推进催化粒子的研究将为理解复杂的相互作用提供集体行为的新例子和新的化学模型系统。 通过肖沃尔特参与涉及国际理论物理中心的外联活动，进一步扩大了工作的影响，这些活动为印度、巴西和喀麦隆等发展中国家的科学家带来了实践研究经验。

Kenneth Showalter of West Virginia University is supported by an award from the Theoretical and Computational Chemistry program for research into the spatiotemporal dynamics and collective behavior of chemical systems. Partial co-funding for this award was provided by the Applied Mathematics program in the Division of Mathematical Sciences. Three main lines of investigation are being pursued in this work: (i) the collective behavior of particle-like reaction-diffusion waves; (ii) the synchronization and dynamical quorum sensing behavior of large populations of oscillatory beads; and (iii) the behavior of collections of self-propelled catalytic particles. In the first project, populations of stabilized waves in a distributed photosensitive Belousov-Zhabotinsky (BZ) medium are being studied to characterize collective behavior in a controlled laboratory setting. Waves interact via a Lennard Jones type potential and the origin of different types of collective behavior, such as processional and rotational modes, is being characterized. In the second project, large populations of catalyst-loaded beads are studied in catalyst-free BZ reaction mixtures. The focus of these studies is to examine synchronization and dynamical quorum sensing behavior in stirred suspensions and spatiotemporal distributed systems. The third project involves studies of the interactions of self-propelled catalytic particles in reactant solutions. Silica spheres are prepared with various metal or enzyme coatings, such as Pt or horseradish peroxidase, that catalyze the decomposition of a reactant, such as hydrogen peroxide. The propagation behavior of these particles is then studied as a function of particle density to determine correlations in velocity leading to collective behavior. All three lines of research are expected to yield new and important information about spatiotemporal dynamics and collective behavior in chemical systems and offer insights into such behavior in biological systems. The studies of interacting particle-like waves will advance control of spatiotemporal systems and will offer insights into collective behavior from laboratory experiments. A better understanding of synchronization and dynamical quorum sensing mechanisms will be gained in the studies of large populations of discrete oscillators, offering insights into related dynamics of microorganisms. The studies of interacting self-propelled catalytic particles will provide new examples of collective behavior and new chemical model systems for developing an understanding of complex interactions. The impact of the work is further broadened through Showalter's participation in outreach activites involving the International Center for Theoretical Physics that are bringing hands-on research experiences to scientists in developing countries such as India, Brazil and Cameroon.