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V K Vanag

Publications and source records attributed to V K Vanag.

8 recordsLinked to original sources
PubMed2001

Pattern formation in a tunable medium: the Belousov-Zhabotinsky reaction in an aerosol OT microemulsion.

Turing structures, standing waves, oscillatory clusters, and accelerating waves have been found in the spatially extended Belousov-Zhabotinsky system dispersed in water droplets of a reverse AOT microemulsion. The variety of patterns is determined by the tunable microstructure of the medium, i.e., by the concentration and size of water droplets. We propose a simple model to describe this system.

Aerosols↗
PubMed2001

Inwardly rotating spiral waves in a reaction-diffusion system.

Almost 30 years have passed since the discovery of concentric (target) and spiral waves in the spatially extended Belousov-Zhabotinsky (BZ) reaction. Since then, rotating spirals and target waves have been observed in a variety of physical, chemical, and biological reaction-diffusion systems. All of these waves propagate out from the spiral center or pacemaker. We report observations of inwardly rotating spirals found in the BZ system dispersed in water droplets of a water-in-oil microemulsion. These "antispirals" were also generated in computer simulations.

Journal Article↗
PubMed2001

Oscillatory clusters in the periodically illuminated, spatially extended Belousov-Zhabotinsky reaction.

Cluster-cluster transitions in the periodically illuminated photosensitive Belousov-Zhabotinsky (BZ) reaction-diffusion system exhibit the same scenario as in the autonomous BZ system with negative global feedback: two-phase clusters <--> three-phase clusters <--> irregular clusters <--> localized clusters. Transitions induced by changing the dark ( TD) or light ( TL) phases of the periodic external square wave illumination are dependent not only on the frequency of illumination at constant TD/TL, but also on the ratio TD/TL at constant frequency (when TD+TL = const).

Journal Article↗
PubMedDate not supplied

[Low temperature reduction of cytochrome c complexes].

The absorption spectra of ferricytochrome c complexes with azide, imidazole and cyanide reduced by trapped electrons at the liquid nitrogen temperature were investigated. Differences have been found between the absorption spectra at T=77 degrees K of cytochrome c complexes reduced by radiation and the absorption spectrum of ferrocytochrome c. These differences are supposed to be due to the axial ligation of the Fe(II) by exogenous ligand. The temperature increase led to the removal of exogenous ligand from Fe(II).

Azides↗
PubMedDate not supplied

[Kinetic analysis of the possible effect of a constant magnetic field on the rate of enzymatic reactions].

The simplest scheme of enzymatic reaction (ER) in which the electronic spins of the enzymatic active centre and substrate (S) equal 1/2 is analysed. It is shown that for delta g-mechanism, as well as for the relaxation mechanism of the action of constant magnetic field (MF) on the electronic spin conversion the conversions between singlet and triplet states of the enzyme-substrate complex can be described by monomolecular reactions with definite constants. The dependence of the rate of steady-state ER upon elementary ER constants and upon singlet conversion constants is obtained by the graph method. It is shown that MF changing the singlet conversion constants can influence the rate of ER under definite correlation between elementary constant of ER. In the case of [S] much less than Km (Km--Michaelis constant) the considered ER is in accordance with the recombination reaction of free radicals (RR) by kinetic characteristics, when [S] approximately greater than Km the specific influence of MF on ER with respect to RR is displayed. Under these conditions the action of MF can grow significantly with respect to RR case depending on the correlation between the elementary constants of ER.

Biophysical Phenomena↗
PubMedDate not supplied

[Influence of magnetic field on hydrogen peroxide decomposition by catalase].

The rate constants of H2O2 decomposition equal to 0.45 X 10(7) M-1S-1 per hem and Michaelis constants higher than 0.3 M were found by gas volume meter and spectrophotometer methods for purified preparations of catalase from bovine liver. Unlike the results obtained earlier the magnetic field with induction 0.65 T and 0.012 T does not affect the constant rate within 3%. It was found with the substrate concentration less than 0.01 M when the classical catalase mechanism was observed and with higher concentration of the substrate up to 0.7 M when the catalase inhibition by H2O2 played an important role.

Animals↗