Controlling the Ru-catalyzed Belousov–Zhabotinsky reaction by addition of hydroquinone

Size- and position-dependent bifurcations of chemical microoscillators in confined geometries

The present theoretical study deals with microparticles (beads) that contain an immobilized Belousov-Zhabotinsky (BZ) reaction catalyst. In the theoretical experiment, a BZ bead is immersed in a small water droplet that contains all of the BZ reaction reagents but no catalyst. Such heterogeneous reaction-diffusion BZ systems with the same BZ reactant concentrations demonstrate various dynamic modes, including steady state and low-amplitude, high-amplitude, and mixed-mode oscillations (MMOs). The emergence of such dynamics depends on the sizes of the bead and water droplet, as well as on the location of the bead inside the droplet. MMO emergence is explained by time-delayed positive feedback in combination with a canard phenomenon. If two identical BZ beads are immersed in the same droplet, many different dynamic modes including chaos are observed.

Small-amplitude and mixed-mode pH oscillations in the bromate-sulfite-ferrocyanide-aluminum(III) system

The BrO(3)(-)-SO(3)(2-)-Fe(CN)(6)(4-) (BSF) pH-oscillatory system is coupled to the Al(OH)(3) precipitation equilibrium (BSFA system) and studied in a stirred flow reactor. The dynamic behavior of the BSFA system differs significantly from that of the BSF system. In addition to the large-amplitude pH oscillations found in the BSF system, new small-amplitude and mixed-mode oscillations occur. A detailed mechanism of the BSFA system is developed and investigated.