ABSTRACT
Labyrinth-like Turing patterns are investigated under the influence of an electric field. The patterns form in the ferroin-catalyzed Belousov-Zhabotinsky reaction embedded in the sodium-bis (2-ethylhexyl) sulfosuccinate (AOT) water-in-oil microemulsion. For two different values of the droplet fraction above and below the percolation transition of the system, the electric field induced drift of the patterns is different. Above the percolation transition, a linear increase of the drift velocity with increasing electric field strength is found. However, below the percolation transition, this increase shows an exponential behavior. The patterns are also observed to reorient under high electrical field strength, such that they are arranged perpendicular with respect to the field lines.
Subject(s)
Emulsions/chemistry , Succinates/chemistry , Algorithms , Diffusion , Electric Conductivity , Electricity , Fourier Analysis , Glass , Linear Models , Nonlinear Dynamics , Oils/chemistry , Solvents/chemistry , Surface-Active Agents/chemistry , Water/chemistryABSTRACT
The dynamic interaction of scroll waves in the Belousov-Zhabotinsky reaction with a vertically orientated gradient of excitability is studied by optical tomography. This study focuses on scroll waves, whose filaments were oriented almost perpendicular to the gradient. Whereas scroll waves with filaments exactly perpendicular to the gradient remain unaffected, filaments with a component parallel to the gradient develop a twist. Scroll waves with U-shaped filaments exhibit twists starting from both of its ends, resulting in scroll waves whose filaments display a pair of twists of opposite handedness. These twists are separated by a nodal plane where the filament remains straight and untwisted. The experimental findings were reproduced by numerical simulations using the Oregonator model and a linear gradient of excitability almost perpendicular to the orientation of the filament.
Subject(s)
Models, Theoretical , Arrhythmias, Cardiac/physiopathology , Heart/physiologyABSTRACT
Using the ferroin- and the bathoferroin-catalyzed Belousov-Zhabotinsky (BZ) reaction embedded in the sodium-bis (2-ethylhexyl) sulfosuccinate (AOT) water-in-oil microemulsion, we observed different patterns occurring in two different solvents, hexane and octane. Turing patterns were found in both solvents with ferroin. They differ in their interaction with coexisting bulk oscillations, such that a new excitation front was formed around the evolving Turing patterns in hexane. However, in octane, the bulk oscillation merged with the evolving patterns, forming a new excitation front, which propagated into two directions: towards the existing patterns and away from them. For the bathoferroin-catalyzed BZ reaction, patterns like dash waves, jumping waves, and bubble waves were found in both solvents having different wavelengths. A curvature dependence of the splitting and merging of dashes was found.
Subject(s)
Microfluidics/methods , Models, Chemical , Oscillometry/methods , Phenanthrolines/chemistry , Solvents/chemistry , Succinates/chemistry , Computer Simulation , Models, Molecular , Pattern Recognition, Automated , Surface PropertiesABSTRACT
The dynamics of scroll waves with a variable orientation to a vertically oriented gradient of excitability is studied by optical tomography in the ferroin-catalyzed Belousov-Zhabotinsky reaction. An almost perpendicular orientation between the scroll wave and gradient induces a pair of twists of opposite handedness on the scroll wave. The position of the nodal plane formed between the twists is governed by the time delay of the twist formation and therefore leads to a symmetric or asymmetric twisted scroll wave. Larger inclinations between scroll wave and gradient cause a drift of the filament along the reactor wall until it reaches the bottom of the reaction container. In this case, the scroll wave does not twist, suggesting that a drift acts as an alternative mechanism of responding to the gradient.