Kenneth Showalter, Ph.D. - US grants

The primary objective of this U.S.-Hungary cooperative research project between Dr. Kenneth Showalter of West Virginia University and Dr. M.T. Beck of Kossuth Lojos University, Debrecen, is to investigate the oscillatory iodate ion oxidation of sulfite and ferrocyanide ions. Efforts will involve characterization and systematic examination of major component processes of this reaction: (1) the direct reaction between iodate and sulfite, (2) the iodine oxidation of ferrocyanide, (3) the triiodide and iodine oxidation of sulfite, and (4) the direct reaction between iodate and ferrocyanide. After classical chemical kinetics studies of these four processes, the researchers will pursue experimental and theoretical studies of the dynamical behavior of the oscillatory reaction. Results should lead to development of an accurate model description of the oscillatory reaction mechanism. This project in physical chemistry fulfills the program objective of advancing scientific knowledge by enabling experts in the United States and Eastern Europe to combine complementary talents and pool research resources in areas of strong mutual interest and competence.

Professor Kenneth Showalter has been awarded a grant from the Experimental Physical Chemistry Program for continued studies concerning the oscillatory behavior of certain chemical reactions in solution and in solution-solid state media. These studies of chemical waves hold great promise for developing a better understanding of spatial and time behavior in chemical systems. A detailed characterization of the oscillatory iodate-sulfite-ferrocyanide reaction will be carried out. Classical chemical kinetics studies of the component reactions along with a systematic investigation of the dynamical behavior will be accomplished. Chemical wave behavior in a variety of different reactions and configurations will be investigated. One particularly innovative component of this study is the investigation of spiral waves on the spherical surface of catalyst beads.

Kenneth Showalter of West Virginia University is supported by a grant from The Theoretical and Computational Chemistry Program to continue his experimental research in the area of spatiotemporal dynamics in chemical systems. Showalter proposes three main lines of research: 1) studies of perturbation-induced spatiotemporal behavior; 2) the development of chemomechanical gel systems that respond to chemical waves and patterns; and 3) studies of spatiotemporal behavior in gas phase reactions. Experimental investigations will be combined with theoretical and computational analyses in each case.

The study of nonlinear dynamics is an important tool for understanding complexity in nature. The dynamics of most biological systems involves spatiotemporal behavior, which remains a challenging and important topic in nonlinear dynamics. Chemical systems play an important role in advancing our understanding of nonlinear dynamics because they are particularly amenable to experimental and theoretical analyses and hence serve as ideal model systems. Showalter's research serves to elucidate the fundamental characteristics of chemical systems that exhibit pattern formation and complex space-time behavior.

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.

Professor Rajarshi Roy of the University of Maryland, with Co-PIs Kenneth Showalter of the University of West Virginia and Harry Swinney of the University of Texas ? Austin, will conduct an Advanced Studies Institute on ?Hands-on Research in Complex Systems? at the University of Buea, Buea Cameroon, for two weeks in July-August 2010.

Intellectual Merit: The ten faculty will be eminent scientists from the U.S. who have conducted frontier research using tabletop instrumentation and who have published their results in journals such as Nature, Science, and Physical Review Letters along with their partners from Cameroon and other African countries. They will be assisted by ten U.S. advanced graduate students and postdoctoral associates. The unique focus of the ASI will be on hands-on laboratory experiments using inexpensive instrumentation leading to frontier scientific advances in understanding complex systems. The laboratory sessions will be complemented by associated mathematical modeling using the software Scilab (which is similar to Matlab), which is available for download, free of charge. The primary goal of the ASI is to develop collaborations for scientific research with African nations. The ASI participants will be advanced graduate students and young scientists and engineers from developing countries in Africa (and a few participants from developing countries elsewhere). The U.S. faculty will benefit by making lasting contacts with scientists from developing countries. The ASI is sponsored partly by the International Centre for Theoretical Physics (ICTP) in Trieste, Italy; ICTP will provide travel funding for participants from developing nations and administrative support for advertising the school and selecting the participants. The ASI will be co-sponsored by the Ministry of Higher Education of Cameroon, and will be held at the University of Buea which will provide laboratories and lecture rooms for Hands-On Research sessions as well as lodging and meals for all participants from Africa and participating countries.

Broader Impact: Participants from the U.S. and developing countries will work closely together conducting experiments and developing mathematical models. The senior faculty and their assistants (whose participation will be made possible by the support of this grant) will lead the hands-on sessions that are the centerpiece of the ASI. These interactions will naturally lead to long term collaborations and exchanges of personnel. The junior faculty (U.S. graduate students and postdoctoral associates) will benefit not only from the interactions with peers who will become leaders in science and technology in developing nations, but also the school will provide the junior faculty with a unique opportunity to hone their own teaching and leadership skills in a unique multi-cultural environment. The senior faculty will present lectures and tutorials on the experiments and numerical modeling. Table-top experiments are particularly well suited for scientific research in developing countries where resources are limited. The interactive sessions will provide a learning experience for faculty as well as the participants, as we all work together to observe phenomena, explore concepts, and raise questions that warrant further study. Our experience as directors of a Hands-On Research on Complex Systems meeting, held in India in January 2008, was that many participants have reported that their participation was a life-changing experience. Building on our experience in India and responding to the suggestions and criticisms of the participants there, we expect that the Hands-On Research on Complex Systems ASI in Cameroon to have lasting impact on the scientific careers of the faculty as well as the school participants.

This award provides partial funding for an advanced study institute (ASI) on complex systems in physics to be held in Shanghai, China, in June 2012. A team of 12 senior researchers and 24 assistants from the U.S. will join colleagues at Shanghai Jiao Tong University (SJTU) to offer a two-week hands-on course demonstrating table-top experiments in complex non-linear physical systems. About 70 participants, primarily junior faculty members, will be selected from underdeveloped regions of Central and Southeast Asia. The objective is to demonstrate that interesting and productive experiments can be conducted with relatively inexpensive and available materials. This ASI is a successor to similar programs that have been held in Africa, India, and Brazil. The local expenses will be supported by SJTU, and participant expenses as well as administrative costs are sponsored by the International Center for Theoretical Physics (ICTP) in Trieste, Italy.
This workshop will engage leading researchers and well qualified post-doctoral fellows and graduate students with participants from underdeveloped regions in Asia to conduct the table-top experiments as well as to introduce useful computer software to the participants. As has already been demonstrated by the previous Hands-on ASIs, these activities stimulate the curiosity of the participants and raise a variety of interest research questions that they can pursue on their own and in continuing collaborations. In addition to raising research issues in the study of complex phenomena the institute demonstrates useful and effective methods of scientific education. This experience is beneficial to the young U.S. assistants as much as to the Asian participants.

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.

In this project funded by the Chemical Structure, Dynamics and Mechanisms Program (CSDM-A) of the Chemistry Division, Professor Kenneth Showalter and his students are studying complex dynamical behavior in chemical systems to gain insights into new types of dynamical behavior in man-made and living systems. Developing an understanding of such behavior in experimental studies facilitates the development of mathematical model descriptions that are relevant to the behavior of certain living organisms as well as synthetic dynamical systems such as computer networks. Research on new states of synchronization and collective behavior will provide insights into basic dynamical behaviors pervasive in living systems. Research on propagating waves in precipitation systems will offer new mechanisms for chemical waves that rely on structural features of the medium, much like wave behavior found in many biological systems.


Networks of coupled chemical oscillators will be investigated in laboratory experiments and computational simulations. The recently discovered chimera state, in which populations of synchronized and unsynchronized oscillators coexist, will be further investigated, with the focus on the spiral chimera state in two-dimensional arrays of coupled oscillators. Further experimental investigations of phase-lag synchronization in networks of coupled chemical oscillators will also be carried out with two-dimensional oscillator arrays, which will allow a wide variety of network topologies and coupling schemes. Theoretically predicted echo phenomena will be investigated in populations of coupled chemical oscillators. Two-dimensional arrays of chemical oscillators will permit sufficiently large populations to allow the detection and characterization of echo behavior. New configurations and examples of propagating precipitation waves will be investigated. Open-reactor configurations will be developed for studies of propagating waves in redissolution precipitation bands based on the amphoteric sodium hydroxide-aluminum chloride system. Unstable spiral wave behavior leading to turbulence-like dynamics will be investigated as well as wave stacking, where waves collide with the waves ahead of them. Further development of a general three-dimensional computational model for propagating precipitation waves will be carried out as well as extending the model to describe wave behavior in open reactor configurations

With support from the Chemical Structure, Dynamics and Mechanisms-A Program (CSDM-A) of the Chemistry Division, Kenneth Showalter and Mark Tinsley and coworkers from West Virginia University will study complex dynamical behavior in chemical systems to gain insights into new types of dynamical behavior in manufactured and living systems. Developing an understanding of such behavior in experimental studies facilitates the development of mathematical model descriptions that are relevant to the behavior of certain living organisms as well as synthetic dynamical systems such as computer networks. Research on new states of synchronization and collective behavior will provide a better understanding of dynamical behaviors pervasive in living systems. The students engaged in this research project are gaining valuable experience in experimental and computational methods for the investigation of dynamical behavior of chemical systems.

Networks of coupled chemical oscillators will be investigated in laboratory experiments and computational simulations. Chemical oscillators exhibit relaxation oscillations similar to the oscillatory dynamics of many cellular systems such as neurons and heart cells. Coupled oscillators therefore offer an ideal platform for investigating biologically relevant dynamics. An example to be investigated here is relay synchronization, in which oscillators in a star network synchronize through a hub oscillator that does not synchronize. This is much like the distal communication of neurons that have seemingly unaffected neurons between them. The Showalter/Tinsley team will also investigate extreme events, in which coupled oscillators undergo a large amplitude oscillation after remaining inactive for unpredictably long time spans. Studies of relay synchronization in multiplex networks, in which complex dynamics is exhibited in layers of coupled oscillators, will be carried out. These multiplex networks are known to exhibit chimera and solitary states, where asynchronous or single oscillators exist in a population of otherwise synchronized oscillators. Recent studies of time-multiplexing show that a single oscillator can replicate to a network of identical oscillators. The team will investigate time-multiplexing to gain insight into the dynamics of populations of identical chemical oscillators, in which modes of synchronization are unaffected by heterogeneity. Finally, the research team will endeavor to develop more robust discrete photochemical oscillators by employing catalyst-loaded tetraethyl orthosilicate (TEOS) beads to significantly increase the length of experiments and decrease drift in dynamical behavior. The broader impacts of this work include potential societal benefits from an increased understanding of cellular interactions in biological systems by detailed studies of coupled chemical oscillators, systems that share important dynamical features with cellular systems. This project will provide for the training of graduate and undergraduate students in experimental and computational methods, and will engage them in the development of computer-interfaced instrumentation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.