Biomedical subjects

A E Arinstein

Publications and source records attributed to A E Arinstein.

3 recordsLinked to original sources

PubMed2005

Uniaxial ordering and rotator phase of ribbonlike polymers.

The phase transition in bended and twisted ribbonlike polymer systems is described in meanfield approximation by use of the lattice model with directed self-correlated walks. This phase transition can be of either first or second order depending on the ratio of the constants in the effective energy of interaction of a polymer with the environment. For the first-order phase transition it is found, in particular, that the phase transition temperature depends on polymer length, decreasing linearly with reciprocal length for lengths exceeding 100 monomer units. On the other hand, the jump of the specific entropy is independent of the polymer length for the molecules containing more than 30 monomers. The obtained results are in full agreement with the existing experimental data.

Journal Article↗

PubMed2005

Conformational statistics of ribbonlike semiflexible polymer chains.

The conformational statistics of ribbonlike polymers possessing bending and twist rigidity are considered on the basis of a lattice model of directed self-correlated walks. It was assumed that local properties of the ribbonlike chain are strongly anisotropic: bending is possible only in the plane of the ribbon (the orientation of this plane can vary due to twist). The generating function for the distribution of a chain segment that is non-Gaussian is constructed. It is shown that in the isotropic environment the twist degree of freedom has no effect on the state of such macromolecules as a whole, and the consideration of rigidity alone in bending results in correct statistical features of a polymer chain. This model is suitable in accounting for the twist degree of freedom in the system with broken rotary symmetry.

Journal Article↗

PubMed2005

Random walks and anomalous diffusion in two-component random media.

The diffusion process in a random media consisting of two different components is studied by a random walk model. The latter is described by three parameters, namely, the fraction p of components, the ratio h of the diffusion coefficients in two components, and the parameter x defining a walker's jumps at the boundary. Depending on the values of these parameters the diffusion can be confined, normal, or anomalous (subdiffusion). The subdiffusion occurs, in particular, for h=0 (trapping model) and for x=0 (excluded volume model).

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