V. B. Nemtsov

Geometric features of the DNA double helix in the supercoiled state

The geometric features of the DNA molecule in the supercoiled state were considered. A model of the supercoiled structure of the DNA molecule was constructed; the model takes into account its natural helicity. The force factors arising in the molecule at various superhelix angles were calculated.

A persistent model of the reptation movement of a DNA molecule

By using a persistent model of the movement of a DNA molecule, the penetration of the DNA molecule into a cell has been described. The method enables one to estimate the time and the rate of passage of the DNA molecule into the cell nucleus. The effect of the curvature of the molecule on its longitudinal movement has been studied. The results obtained can be applied to characterize long chain molecules.

Circular closed DNA. Topology, energy, and stress at different equilibrium configurations and deformation conditions

The topology of circular closed DNA in different equilibrium configurations and deformation conditions has been investigated. The distribution of twisting and bending energy and stress has been assessed. It is shown that the twisting/bending stiffness ratio qualitatively influences the deformation of a circular DNA molecule.

Circular closed DNA. Theory of formation of the first supercoil

The equilibrium configurations of a circular closed DNA molecule, from the ring to the first supercoil (figure of eight), have been determined by the methods of elasticity theory. The description of the topological characteristics allows one to assess the linking number, twisting, writhing, and supercoil density immediately from the model for any equilibrium configuration of the DNA molecule. This enables one to estimate the influence of external factors on the properties and the state of closed DNA molecules.

Rheology of Liquid‐Crystalline Polymeric Systems

Based on the Zubarev method of nonequilibrium distribution functions, a statistical‐mechanical theory of the rheological properties of liquid‐crystalline polymers has been constructed. The distinctive features of the media in question in the case of shear flow have been described using this theory.

Determination of the Dynamic Characteristics of Liquid‐Crystalline Polymeric Systems

A theoretical description of the dynamic phenomena in liquid‐crystalline polymeric systems in periodic mechanical disturbances in terms of the shear modulus and the loss modulus has been given. The rheological characteristics (dynamic viscosity, accumulation modulus, loss modulus, and others) of a synthesized sample of a liquid‐crystalline polymeric system — aromatic polyamide — and the critical concentration of its transition from the isotropic state to a liquid‐crystalline phase have been determined experimentally.

Statistical Calculation of the Viscous Properties of Nematic Liquid Crystals by Means of the Kinetic Equation for the Tensor Order Parameter

We carried out statistical calculation, of the viscosity coefficients of nematic liquid crystals. As the starting point of calculation, we used the expression for the tensor of viscous stresses obtained within the framework of the relaxational hydrodynamics of investigated media constructed on the basis of Zubarevs method of nonequilibrium statistical ensembles. The relaxational equation for the tensor order parameter was used to calculate the time correlation functions that determine kinetic coefficients. The results of theoretical calculations were compared with experimental data on the temperature dependence for a number of nematogens.

Evaluation of the Force Constants of a DNA Molecule Using Its Model in the Form of Coil Springs

An analysis of the force coupling constants used in the models of a DNA macromolecule is made. Expressions for evaluation of the flexural and torsional rigidity of the macromolecule skeleton which are based on one mole and on a pair of bases are provided. For the first time, analytical formulas to calculate the force coupling constants are given.