PubMed Health⌕ Search

Biomedical subjects

A S Bakai

Publications and source records attributed to A S Bakai.

3 recordsLinked to original sources

On the role of frustration on the glass transition and polyamorphism of mesoscopically heterophase liquids.

The model of heterophase fluctuations is developed accounting frustration of the mesoscopic solidlike fluctuons. Within the framework of this model, the glass transition and polyamorphous transformations are considered. It is shown that the frustration increases the temperature range in which the heterophase liquid state exists. the upper and lower boundaries of this temperature range are determined. These boundaries separate different phase states-amorphous solid, heterophase liquid, and fluid phases. Polyamorphous liquid-liquid transitions in the liquid are investigated. Frustration can call forth continuous fluid-solid phase transformation avoiding the first- or second-order phase transition. Conditions under which the first-order phase transition fraction takes place are formulated. Two scenarios of the first-order liquid-liquid polyamorphous transformation are described. As an example the glacial phase formation and the first-order liquid-liquid phase transition in triphenyl phosphate are considered and discussed. Impact of frustration on the liquid crystallization and crystallinity of the glassy state is studied.

Journal Article↗

Nature of long-range correlations of density fluctuations in glass-forming liquids.

Based on a concise review of the experimental data, a theory of the structural, kinetic, and dynamic features of the Fischer cluster is put forward. This theory is based on the idea of heterophase fluctuations of glass-forming liquids. According to these ideas in a one-component liquid the solidlike and fluidlike transient associations of molecules (fluctuons) are formed. The fluctuons differ in the short-range order and, consequently, in the free energy. They form a random free energy landscape. The random field free energy functional of the Ginzburg-Landau type, which accounts for the free energy landscape, is deduced. Based on this, the phase equilibrium, critical behavior, and ordering phenomena of the heterophase liquid are considered. It is shown that in the critical region an effective attractive interaction of the fluctuons results in their gravitation and formation of correlated fractal aggregations. The aggregation consists of the fluctuons of similar short-range order. The fractal aggregation formation is a special structural state of the liquid above the glass transition temperature. The condition at which the aggregations are formed is formulated. Thus it is shown that the Fischer cluster is an array of fractal aggregations of fluctuons. The growth kinetics and dynamics of the Fischer cluster are described. The experimental data are analyzed and discussed using the theory that is put forward.

Journal Article↗

Small isotope effect of diffusion in disordered structures.

The isotope effect E of a single jump vacancy diffusion mechanism in statically disordered lattices is investigated by Monte Carlo simulation. It is found that E decreases significantly with increasing disorder. This effect is attributed to percolation processes and ensuing reduction of the effective dimension of space for the diffusing particle.

Journal Article↗