Experiments and modeling of the Belousov-Zhabotinsky reaction with 1,4-cyclohexanedione and ferroin
AdvisorWinfree, Arthur T.
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PublisherThe University of Arizona.
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AbstractWe describe some observations during the induction period (IP) of a Belousov-Zhabotinsky (BZ) system with 1,4-cyclohexanedione (CHD) and ferroin in batch reactor. There are three stages during the whole course of the reaction: transitional period, the IP, and the post-IP. Two bifurcations are observed in this unique system: It starts with monostability (orange reduced steady-state) during the transitional period, switches to bistability (both blue oxidized and orange reduced steady-states) during the IP, and then eventually bifurcates to monostability (orange reduced steady-state) during the end of the IP. The stable orange steady-state is always excitable during the whole course of the reaction. The stable blue steady-state is not excitable during the blue IP: pulses cannot propagate and pacemakers cannot survive during this interval. As the medium ages, waves decrease their propagation speed except for the reduction step that speeds up during the end of the IP. We also investigate the change of ferroin and ferriin concentrations and photosensitivity during the IP. We find no analog to the situation suggested in the bromate-MA-ruthenium system, in that the oxidized state is experimentally excluded as the photosensitive species in this bromate-CHD-ferroin system. We construct here an Oregonator-like model that interprets the unique reduction step propagation before the second bifurcation. Based on the FKN mechanism with, we consider three reverse reactions, a breakdown of skeletal process C in the FKN model into three reactions with the addition of the hydrolysis of BrCHD. The model thus constructed endows bistability in some region of its parameter plane. We give a tentative interpretation of the differentiated speed between the reduction step propagation and that of the pulses, but rigorous mathematical mechanism awaits further investigation.
Degree ProgramGraduate College
Ecology and Evolutionary Biology