The beautiful target and spiral patterns exhibited by the Belousov-Zhabotinsky (BZ) reaction in thin films of solution are representative of spatiotemporal behavior in a two-dimensional, planar excitable medium. 14 We report here BZ chemical waves propagating on the two-dimensional surface of a sphere. Singleand double-rotor spiral waves develop on the surface of a single cation exchange bead, ...

We describe an improved Taylor dispersion method for four-component systems, which we apply to measure the main- and cross-diffusion coefficients in an Aerosol OT water-in-oil microemulsion loaded with one of the reactants of the Belousov-Zhabotinsky (BZ) reaction, water(1)/AOT(2)/R(3)/octane(4) system, where R is malonic acid or ferroin. With [H(2)O]/[AOT] = 11.8 and volume droplet fraction ph...

The acidic bromate oxidation of ferroin in batch reaction proceeds with slow consumption of bromide until a critical bromide concentration is attained. At that point ferroin is suddenly oxidized to ferriin in a process involving autocatalytic generation of bromous acid. Prior to the transition, in an unstirred thin film of solution, a single trigger wave of chemical reactivity may develop and s...

An optoacoustic technique for solutions of strongly light-absorbing analytes at 0.1-0.01 mol l(-1) is proposed. The technique is based on the wide-band forward mode detection of temporal profiles of laser-generated ultrasonic pulses (optoacoustic signals). The leading edge of the signal repeats the distribution of the laser fluence in the medium, which makes it possible to determine its optical...

The behaviour of a system composed of malonic acid (MA), KBrO3, H2SO4, and ferroin was investigated in batch experiments at various concentrations of oxygen above the chemical mixture when changing the concentration of MA. We could observe that at 10% of oxygen or more and for initial concentrations of malonic acid [MA]0 between 0.15 M and 0.6 M the system attains an equilibrium by some of mixe...

We obtain the diffusion matrix, D, consisting of the main and cross-diffusion coefficients for a loaded AOT microemulsion, a quaternary system containing water (1)/AOT (2)/species (3)/octane (4). Here "species" is a component of the Belousov-Zhabotinsky reaction: NaBr, NaBrO(3), bathoferroin, ferroin, or Br(2). The main and cross-diffusion coefficients of each species depend crucially on its so...

A simple, sensitive, and convenient spectrophotometric method for the determination of diclofenac sodium and piroxicam in pure form and in pharmaceutical formulations was developed. The method is based on the oxidation of diclofenac sodium or piroxicam by iron(III) in the presence of o-phenanthroline. The formation of tris(o-phenanthroline) iron(II) complex (ferroin) upon the reaction of diclof...

Autowaves spreading in a thin layer of the Belousov-Zhabotinsky reaction with ferroin catalyst immobilized in silica gel have been studied. It is found that there is a critical thickness of this layer such that autowaves could not propagate in thinner layers. The results of computer simulations in the two-variable Rovinsky model qualitatively fit the experimental data for the temperature range ...

We measure cross-diffusion coefficients in a five-component system, an aerosol OT (AOT) water-in-oil microemulsion loaded with two constituents of the Belousov-Zhabotinsky (BZ) reaction (H(2) O/AOT/BZ1/BZ2/octane). The species BZ1 is either NaBr, an inhibitor of the BZ reaction, or ferroin, a catalyst for the reaction. As species BZ2, we choose Br(2) , an intermediate in the reaction. The cross...