Oliver Steinbock, Dr. rer. nat. - US grants

Oliver Steinbock of Florida State University is supported by the Theoretical and Computational Chemistry Program to examine pattern information in homogeneous and micro-structured chemical systems, and to develop novel experimental methodologies for control of the underlying spatial coupling. The chemical origins of the anomalous dispersion in the 1,4-cyclohexanedione Belousov-Zhabotinsky (CHD-BZ) reaction will be investigated, and the results utilize to formulate a reaction model capable of reproducing experimental observations from stirred reaction systems. Combined numerical and experimental approaches will be used to distill the characteristic features of spatially extended media, and also to analyze the interplay of attractive and repulsive interactions between traveling oxidation pulses and the resulting shock-like front dynamics. In other studies, the CHD-BZ reaction will serve as a model for chemical self-organization in large arrays of coupled micro-reactors. Recently developed methodologies, such as soft photolithography, will be applied for construction of custom-made arrays in which each reactor will hold a polymer-bound CHD-BZ volume of less than 100 picoliters. These reactor arrays will be employed to examine a broad spectrum of chemical instabilities that give rise to novel wave structures and Turing-like patterns. Results are expected to lead to experimental strategies to control reactions on micro-patterned reactor chips and a thorough understanding of the rules that govern spatial coupling of localized "lab-on-a-chip" processes. Ultimately, the outcomes will contribute valuable information for systematic exploration of compartmentalized reaction-transport systems of the sort that are successfully exploited by living matter for a variety of complex syntheses and sensors.

This research project is highly interdisciplinary because its fundamental results will aid in the analysis of complex systems in biology and elsewhere. In particular, the outcomes will impact the diverse fields of neurophysiology, engineering, and statistical physics. Moreover, the development and fabrication of spatially coupled micro-reactor arrays is expected to have promise for future applications in advanced combinatorial chemistry. The manufactured reactor arrays will be made broadly available to other research groups for their use.

A grant has been awarded to the Florida State University under the direction of Dr. Fredrik Ronquist for partial support of the acquisition of a scanning electron microscope with a field emission gun, a variable-pressure specimen chamber, a cryotransfer unit, and an elemental microanalysis unit. The equipment will offer a number of microscopic examination techniques that are not available today in the north Florida region and will be used by biologists, chemists, engineers, and geologists at the Florida State University and the Florida Agircultural and Mechanical University and by colleagues at other universities and colleges in the region.

The field emission gun allows imaging with extraordinary contrast and large depth of focus at both low and high magnifications. It also gives greatly improved performance at low acceleration voltages, which allows high-magnification examination of uncoated samples or samples that have a tendency to charge and alter in the electron beam. The possibility of raising the pressure in the examination chamber by introducing a gas can also help in the examination of sensitive samples. The cryotransfer equipment is used for rapid freezing of a specimen for subsequent transfer in the frozen state into the microscope chamber. With this equipment it is possible to observe unfixed frozen material in its natural state. Finally, the X-ray microanalysis equipment allows analysis of the composition of the sample surface.

The new instrument will be used for a wide range of applications including studies of polymers; cellular and tissue details important in medical engineering; /Drosophila/ mutants; teeth and other skeletal structures in dinosaurs, birds and mammals; skeletal morphology of hymenopterans (ants, wasps and bees); flower morphology; and structure of clays and fossil diatom assemblages in deep sea sediments. Five research groups in Chemistry are studying different types of novel materials based on nano-scale manipulation. The new microscope equipment will support the research of many faculty members but will also be used in education and research training of underrepresented groups. Other examples of activities with broad impact that will benefit from the new equipment include Sir Harold Kroto's efforts to popularize science through the Vega Science Trust, the first free Internet broadcaster of science programs, and the MorphBank project, aimed at providing a web platform for international collaboration in image-based biological disciplines such as comparative morphology and biodiversity research.

Oliver Steinbock of Florida State University is suuported by a grant from the Theoretical and Computational Chemistry program wihin the Division of Chemistry for research on filament dynamics in three dimensional reaction-diffusion systems. A systematic study of three dimensional chemical waves in a variant of the Belousov-Zhabotinsky (BZ) reaction is being carried out to test theoretical predictions of interesting scroll waves rotating around circular filaments and other complex wave dynamics. These new experiments are significantly expanding the number of experimental studies of this important reaction thought to be a model for excitable media in biological systems, such as cardiac and neural tissue. Steinbock's research group is devising new experiemental strategies that will allow the controlled fabrication of heterogeneous three dimensional systems that may mimic the heterogeneities found in biological tissue. Cardiac tissue, in particular, is suggested to have the same type of dynamical properties as the BZ medium, so broader impacts are expected in the understanding of sudden cardiac death, shown in prior theoretical studies to be related to the filament dynamics to be studied here.

TECHNICAL SUMMARY

This project focuses on inorganic, tubular materials formed during spatially controlled reaction processes. These hollow tubes have inner radii 1-100 µm and result from the precipitation of amorphous silica and metal hydroxides. The overall phenomenon is not well understood and its potential as a model case for system-level materials science widely unexplored. Under this grant, supported by the Solid State and Materials Chemistry program of the Division of Materials Research, the PI will develop a pressure-controlled reactor system to produce millimeter-long microtubes with radii of down to 1 µm. In addition, the size and shape of these microtubes will be controlled using variable electric fields and pressure changes. Another central goal is to nano-engineer the physico-chemical characteristics of the tube wall by binding, trapping and adsorbing a variety of molecules and particles. Moreover, the group will integrate tubes into microfluidic devices where they will add functionalities such as enhanced separation regions, chemical sensors, and catalytic processing stations. These experimental projects will be complemented by modeling efforts that aim to develop a reaction-transport model capable of capturing key aspects of the large-scale growth dynamics based on the precipitation kinetics, diffusion, and advection processes. An important part of the broader impact of this project is to communicate its key ideas and results to non-experts. The project will pursue this goal through a multi-faceted video outreach program. In addition, it will advance the education of undergraduate, graduate and postdoctoral students at the Florida State University.

NON-TECHNICAL SUMMARY

Modern technologies produce materials and devices in ways that differ fundamentally from the strategies employed by biological systems. These differences are the likely explanation as to why materials with hierarchical architectures and self-healing features tend to elute conventional engineering approaches but are abundant in biology. A key question in this context is how chemical reactions can cause the formation of complex structures that are thousands to millions times larger than the individual molecules. The project will tackle this big question by studying inorganic reactions that are known to produce hollow tubes. The diameter and length of these rigid structures is comparable to human hair but can also be significantly thinner. The tube walls typically consist of amorphous silica (porous glass) and metal hydroxides or oxides, which create interesting catalytic and optical properties. If successful, this research will (i) result in quantitative models of nano-to-macro growth processes, (ii) provide reactor systems that can shape the tubes during growth, (iii) demonstrate chemical modifications of the wall material that introduce chemical sensing and/or processing capabilities, (iv) explore applications towards uses in microfluidic and lab-on-a-chip technologies. The project also aims to communicate its scientific ideas and results to non-experts. The intriguing life-like appearance and overall visual appeal of the basic phenomenon will greatly assist in this effort. Specific plans include targeted video outreach through FSU's Global Educational Outreach Program, Podcasts, and popular websites such as YouTube. In addition, the project will advance the education of several undergraduate, graduate and postdoctoral students. The PI will also continue his commitment to involve underrepresented groups and participate in programs that aim to increase their leadership roles in research and academia.

In this award, funded by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, the research group of Professor Oliver Steinbock (Florida State University, FSU) will investigate self-organizing wave patterns in autocatalytic reaction-diffusion systems. These far-from-equilibrium systems are a treasure trove for 21st century science. They create intricate regulatory networks, exhibit fascinating dynamics, and generate information-relaying patterns that one typically expects to find only in biology. The project focuses on understudied processes in three-dimensional excitable media and specifically on rotating scroll waves. These dissipative structures are formed by propagating regions of autocatalytic activity and trailing "refractory zones" of high inhibitor concentration. The primary goal is to establish a complete description of vortex pinning and vortex unpinning in three-dimensional excitable systems. An important example is the distinction between true pinning to small heterogeneities and mere surface termination of the vortices' rotation backbone. Experiments will include weakly excitable, curved, and moving heterogeneities that should allow the active repositioning and reshaping of scroll waves. These challenging studies can be pursued using photochemical methods and/or computer-controlled motion of solid objects. The latter approach will induce fluid flow in the reactive solution but should not affect pattern stability below threshold values that the will be characterized systematically during the project. If successful, these studies will also provide a novel approach to chemo-hydrodynamic systems. Another goal is to demonstrate and analyze the unpinning of scroll rings from heterogeneities in BZ-gel systems using externally controlled electric fields and temperature gradients. The project will test a hypothesis that unpinning can proceed via tilting of the scroll ring relative to the pinning, torus-shaped anchor or alternatively via radial expansion. These investigations will be complemented by kinematic modeling efforts and computational studies of three-dimensional reaction-diffusion models.

Much of the chemical research under this project is motivated by the self-organization of living systems. A striking example is the motion of electrical patterns in the human heart that orchestrate the healthy or disturbed pump action of this vital organ. Spinning, vortex-like states have been linked to tachycardia and ventricular fibrillation with the latter being among the leading causes of death for Americans. Highly reproducible experiments with simpler chemical systems have and will reveal important insights into these states. The research team around Prof. Steinbock will specifically investigate how such vortices are changed, reshaped, and possibly stabilized by less active regions. In the context of the heart such regions correspond to scar tissue caused by traumatic events such as heart attacks. This multi-faceted research is also ideally suited for the modern training of undergraduate, graduate, and postdoctoral students. Furthermore Prof. Steinbock will continue his firm commitment to foster underrepresented groups and participate in mentoring programs that aim to increase their leadership roles in research and academia. Specific activities include the production of videos for FSU's Global Educational Outreach Program and YouTube. In addition, Prof. Steinbock will participate in FSU's Honors Research Program for first-year students and contribute to the "Saturday Morning Physics" lecture series for local pre-college students.

Non-Technical Abstract:

Living systems produce materials and device-like structures in ways that differ profoundly from most existing engineering strategies. They are capable of growing high-performance materials (e.g. bone and tooth enamel) with intricate micro-to-macro architectures by tightly regulating the process conditions. In addition, life accomplishes these feats from inexpensive and abundant starting materials. With the support of the Solid State and Materials Chemistry program, the overarching goal of this project is to find and develop examples that use similar strategies in the realm of non-biological, inorganic chemistry. If successful this research could form an important stepping stone towards an entirely new engineering paradigm under which materials are produced by externally controlling chemical self-organization and other complexity-generating mechanisms. This research effort is integrated with educational and outreach activities that include the training of undergraduate and graduate students and the dissemination of research videos via social media. The principal investigator also plans to develop a website dedicated to "chemical gardens" which are the most iconic example of self-organizing inorganic reactions. The website aims to provide information for high school teachers and invites photo competitions documenting these chemical structures.



Technical Abstract:

This project explores pattern-forming, nonequilibrium processes in the context of inorganic precipitates with the aim to advance the understanding of macroscopic tube structures and micro-scale nanorod assemblies called biomorphs. Some of these studies are inspired by origins-of-life hypotheses under which prebiotic chemistry developed in the microporous and catalytically active precipitates of off-axis alkaline hydrothermal vents. Specific goals include the prediction of tube formation from simple chemical and physical parameters and the use of related materials for the study of transmembrane transport, thermophoretic effects, and specific aspects of the formose reaction. This calcium-hydroxide-catalyzed reaction generates numerous products including ribose from formaldehyde and has been discussed in the context of RNA world theories. The second research thrust focuses on biomorphs that form in silicate-barium solutions under the influx of carbon dioxide. These 10-100 micrometer large structures have life-like morphologies such as cardioidal sheets and helices and consist of highly ordered aggregates of barium carbonate nanorods. To elucidate their growth mechanism and nano-to-macro architecture, the research team develops mean-field reaction-transport models. The modeling and simulation efforts are based on experiments aiming to identify mechanistic details from flow and electric-field induced perturbations.

In this project funded by the Chemistry Division (Chemical Structure, Dynamics and Mechanisms A), Professor Oliver Steinbock (Florida State University) is studying how seemingly simple chemical reactions can form complex life-like patterns. Chemical reactions in a laboratory container can produce macroscopic patterns that include rotating spirals that appear visually as striking blue bands on a red background. Closely related spirals exist as electrical phenomena also in the human heart where they cause life-threatening conditions and are among the leading causes of death in the US. Professor Steinbock and his students will investigate the behavior of these spiral waves in thick layers that model the heart focusing on specific questions including the effect of height variations. They will also study the pinning of these spirals to inert areas that correspond to anatomical features and scar tissue formed after heart attacks.

This project uses the autocatalytic Belousov-Zhabotinsky (BZ) reaction and numerical simulations of reaction-diffusion models to investigate self-propagating concentration waves. In three dimensions, these nonlinear waves can take the form of vortices that rotate around one-dimensional phase singularities called filaments. Filament motion can generate a form of spatio-temporal chaos that shares many dynamical similarities with ventricular fibrillation in the human heart. The effect of non-reactive heterogeneities on periodic and chaotic vortices will be investigated with a focus on the defect-mediated suppression of turbulent states as well as the translational motion of vortices along step edges. Another component is the study of vortex pinning in higher dimensional networks. The outreach program includes the dissemination of key results and pertinent background information to laymen and teachers using YouTube videos and other internet-based resources.