Amplitude Control of Chemical Waves in Catalytic Membranes. Asymmetric Wave Propagation between Zones Loaded with Different Catalyst Concentrations

Abstract

Chemical waves of the Belousov−Zhabotinsky type are studied applying bathoferroin catalyst fixed on a polysulfone membrane. A new method is developed to create contacting high- (H) and low-amplitude (L) regions for chemical waves. The amplitude is high in zones (H) loaded with high catalyst concentrations, and it is low in zones (L) loaded with low catalyst concentrations. An asymmetric wave propagation is found: waves coming from region H can initiate waves in region L across the HL boundary with a higher frequency than vice versa. The ratio of the cross-recovery times R(L → H) and R(H → L) is 1.7 in the experiments reported here. To measure this ratio, rotating chemical waves were applied. The waves propagate in two concentric annular zonesthe inner zone with low and the outer with high catalyst concentrationand the HL boundary forms a circle. It was found that in such a reactor complex wave patterns (so-called chemical pinwheels) can rotate nearly independently in the H and L zones, interacting only weakly across the HL boundary.

Stochastic cellular automata modeling of excitable systems

“…Indeed, if the curvature is small enough then its effect can be neglected [32] (see Figure 2 therein). For the corresponding experimental studies, we refer to [33,34,[36][37][38] and for numerical simulations see [39]. Our simulations are in good accordance with these experiments, see Figures 5 (a), (b) and (c).…”

Diffusive Propagation of Chemical Waves through a Microgap

“…The frequency change of chemical waves mentioned above is a result of the propagation failures of chemical waves at the gap. The propagation failures can be explained on the basis of a simplified picture based on the concept of refractoriness. , That means the success or failure of the chemical wave propagation can be explained by the next conditions:…”

“…On the other hand, biological systems are extremely inhomogeneous and have spatial structures. Recently, investigations on chemical waves in the presence of various inhomogeneities became active in order to provide some insights into the spatiotemporal pattern formations in biological systems. − …”

Unidirectional Propagation of Chemical Waves through Microgaps between Zones with Different Excitability

“…Chemical waves propagating in Belousov−Zhabotinsky (BZ) solutions have been thought to be a convenient model of waves in biological excitable media such as heart muscles and brain tissues. − Most of the basic properties of the chemical waves have been revealed by experimental and theoretical studies on the chemical waves observed in spatially uniform BZ solutions. − Recently, the propagation of chemical waves in inhomogeneous BZ systems has also come to occupy an important position in studies on the chemical waves, − because biological excitable media are clearly inhomogeneous. The effects of geometrical shapes 9-14 and inhomogeneity of refractoriness 15,16 or excitability 17,18 of the excitable BZ media on the chemical wave propagation can be investigated by using modified BZ systems with fixed catalysts.…”