Scroll Wave Dynamics in Heterogeneous Reaction-Diffusion Systems

在这项由化学系化学结构、动力学和机制计划资助的奖项中，佛罗里达州立大学Oliver Steinbock教授的研究小组将研究自催化反应-扩散系统中的自组织波型。这些远离平衡的系统是21世纪科学的宝库。它们创造了错综复杂的监管网络，展示了迷人的动态，并产生了人们通常期望在生物学中才能找到的信息传递模式。该项目专注于三维可激发介质中未被研究的过程，特别是旋转涡旋波。这些耗散结构是由自催化活性的传播区和高浓度缓蚀剂的拖尾“耐火区”形成的。主要目标是建立三维可激发系统中涡旋钉扎和涡解钉扎的完整描述。一个重要的例子是区分真正的钉扎到小的非均质性和仅仅是涡旋旋转主干的表面终止。实验将包括弱可激发、弯曲和移动的不均质性，这些不均质性应该允许主动重新定位和重塑涡旋波。这些具有挑战性的研究可以使用光化学方法和/或计算机控制的固体物体的运动来进行。后一种方法将在反应溶液中诱导流体流动，但不应影响低于阈值的模式稳定性，该阈值将在项目期间系统地描述。如果成功，这些研究还将为化学-流体动力学系统提供一种新的方法。另一个目标是使用外部控制的电场和温度梯度来演示和分析BZ-Gel系统中非均质涡旋环的解钉。该项目将测试这样一种假设，即解锁可以通过涡旋环相对于钉扎的环状锚倾斜进行，或者通过径向膨胀进行。这些研究将得到运动学建模工作和三维反应扩散模型的计算研究的补充。该项目下的大部分化学研究都是由生命系统的自组织推动的。一个引人注目的例子是人类心脏中的电子模式的运动，这些模式协调着这个重要器官的健康或紊乱的泵浦动作。旋转、漩涡状状态与心动过速和室颤有关，后者是美国人的主要死亡原因之一。用更简单的化学体系进行的高度可重复性的实验已经并将揭示对这些状态的重要见解。斯坦博克教授周围的研究小组将专门研究这种涡旋是如何改变、重塑的，并可能被不太活跃的区域稳定下来。就心脏而言，这些区域对应于由心脏病发作等创伤性事件造成的疤痕组织。这种多方面的研究也非常适合现代本科生、研究生和博士后的培养。此外，斯坦博克教授将继续他的坚定承诺，培养代表不足的群体，并参与旨在提高他们在研究和学术领域的领导作用的指导计划。具体活动包括为FSU的全球教育推广方案和YouTube制作视频。此外，斯坦博克教授还将参加外国语大学一年级学生的荣誉研究项目，并为当地预科学生的“周六早晨物理”系列讲座做出贡献。

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.