In this project, funded by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, the Professor Kenneth Showalter of West Virginia University and his students will investigate three main lines of research: (i) the dynamics and collective behavior of self-propelled particles, (ii) the propagating target and spiral waves in precipitation reactions, and (iii) the synchronization behavior in populations of coupled chemical oscillators. In the first project, studies of collective behavior in populations of self-propelled particles, such as Pt-silica particles in hydrogen peroxide solutions, are carried out to determine the mechanism of inter-particle interactions. New self-propelled particle systems based on enzyme catalysis and surface catalyzed reactions are being developed and the motion of n-mer particle aggregates is being characterized. In the second project, studies of recently discovered propagating waves in the precipitation front of the NaOH-AlCl3 reaction are conducted. The positive feedback giving rise to the propagating wave behavior is being characterized and new precipitation systems exhibiting propagating waves are being developed. The third project involves studies of populations and networks of coupled chemical oscillators. The theoretically predicted chimera state, with coexisting subpopulations of synchronized and unsynchronized oscillators, is studied experimentally and computationally by using light-sensitive, catalyst-loaded particles in catalyst-free Belousov-Zhabotinsky reaction mixtures. Self-optimization of link weights in biomimetic networks of oscillators controlled with an algorithm for spike-timing dependent plasticity is also being studied.
All three lines of research are expected to yield new and important information about collective behavior and spatiotemporal dynamics in chemical systems and offer valuable insights into dynamic behavior in biological systems. The studies of self-propelled particles will provide mechanistic insights into the propulsion and interaction of biological unicellular organisms, such as bacteria and algae. The studies of propagating target and spiral waves in precipitation systems will offer new mechanisms for chemical wave propagation that rely on structural features of the medium, much like wave propagation in many biological systems. The studies of new states of coexisting synchronized and unsynchronized coupled chemical oscillators and self-optimization in networks of chemical oscillators provide insights into basic dynamical behaviors pervasive in living systems. The research program is expected to have a broad local impact from the integration of research and teaching into the university curriculum. The impact of the work is further broadened through outreach activities involving the International Center for Theoretical Physics that bring hands-on research experiences to scientists in developing countries in Asia, Africa, and South and Central America.
