Spatiotemporal Dynamics and Collective Behavior in Chemical Systems

West Virginia University Research Corporation, Morgantown WV

Investigators

Abstract

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.