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S K Aityan

Publications and source records attributed to S K Aityan.

5 recordsLinked to original sources
PubMed1988

Analysis of models of single-file diffusion.

Theoretical models of single-file transport in a homogeneous channel are considered. Three levels of channel populations were specified for which different approximations could be used. The results of these approximations are in good agreement with the results of a computer experiment (Aityan and Portnov 1986). At low populations, the pair correlation functions were negligibly small and allowed the use of linear approximation for unidirectional fluxes and populations. The value of the pair correlation function and the respective approximation for fluxes was obtained by the two-particles random-walk technique. At extremely high populations, the "divider" technique was proposed to describe the single-file transport. The divider technique allowed to explain the exponential shape of the pair correlation function FABn, n + 1 profile at extremely high populations. At medium populations the finite difference superposition approximation was valid.

Computer Simulation↗
PubMed1986

Simulation of molecular dynamics of water movement in ion channels.

The motion of water molecules in a gramicidin-like channel was studied by the molecular dynamics method. Water molecules are presented in the ST2 model. The structure of the channel was presented in the form of channel's helix frame possessing mobile dipole groups. The interaction of all mobile particles with the membrane channel's walls was taken into account. The calculation consisted of 50,000 integration steps of delta t = 5 x 10(-16) s which corresponded to a total elapsed time of 25 ps. It was shown that water molecules in the channel did not possess rigid spatial structure but exhibited a structure oriented along the channel axis. The motion of water molecules in the channel occurred smoothly, i.e. all water molecules did not have any deep, stable potential wells in the channel. The distribution of water molecules along the radial coordinate of the channel was estimated. Water density was shown to be maximal near the channel axis.

Chemical Phenomena↗
PubMed1986

Computer simulation of single-file transport.

A stochastic model of single-file transport was developed as the Markov process in continuous time technique. The model was constructed using an EC-1060 computer. Unidirectional fluxes were investigated and populations of channels were correlated with flux fluctuations. The profiles of channel populations were shown to have nonlinear shapes even with the transport of nonelectrolyte (the classical diffusion approach gives linear profiles). The relationship between the paired correlation function F(AB) and the concentration of transported particles was examined. The F(AB) profile was shown to become flattened (or exponential for asymmetrical cases) at high concentrations. The concentration dependence jA/jA0 ratio were analyzed, where jA is a single-file unidirectional flux, jA0 is unidirectional flux for the case of free diffusion. An interesting "stack" phenomenon was observed for abnormal time correlations of single-file fluxes.

Biological Transport↗
PubMed1985

Single-file diffusion of uncharged particles.

An equation for unidirectional fluxes of nonelectrolytes and for the total flux in the single-file transport through a narrow pore has been derived. The equation obtained accounts for the correlations of the population of the pore in the coordinate of transport. The problem has been solved using superposition approximation and unidirectional fluxes has been found. The population profile in the pore was shown to have nonlinear shape; this is principally different from the results of the classical diffusion approach.

Biological Transport↗