phase transition

Influence of the uniaxial stress $p_2$ and transverse fields $E_1$ and $E_3$ on the phase transitions and thermodynamic characteristics of GPI ferroelectric materials

A modified GPI model that accounts for the piezoelectric coupling between the ordered structural elements and the strains $\varepsilon_j$ has been used for studing of effects arising in GPI ferroelectrics under the action of the uniaxial stress $p_{2}$ and electric fields $E_1$ and $E_3$.  The  polarization vectors and components of static dielectric permittivity are calcucated in the two-particle cluster approximation for mechanically clamped  crystal, and piezoelectric and thermal parameters are also determined.  The influence of the simultaneous action of the stress

Coil-Uncoiled Chain Transition of Polyethylene Oxide Solutions under Convergent Flow

The coil-uncoiled chain transition under convergent flow of polyethylene oxide aqueous solutions has been studied. The possibility of this transition has been confirmed by the experiments. The fields of velocities and their gradients arising at the entrance of a small capillary during the convergent flow have been examined. It was found that water-polyethylene oxide system under convergent flow and certain flow regimes is self-regulating one with a negative feedback.

Solving Stefan's linear problem for drying cylindrical timber under quasi-averaged formulation

The plain problem of drying of a cylindrical timber beam in average statement is considered.  The thermal diffusivity coefficients are expressed in terms of the porosity of the timber, the density of the components of vapour, air, and timber skeleton.  The problem of mutual phase distribution during drying of timber has been solved using the energy balance equation.  The indicators of the drying process of the material depend on the correct choice and observance of the parameters of the drying medium.

Calculation of transverse piezoelectric characteristics of quasi-one-dimensional glycine phosphite ferroelectric

The model of the glycine phosphite crystal, modified by taking into account of piezoelectric coupling of ordering structure elements with the lattice strains, is used for investigation of piezoelectric characteristics of the crystal. In the frames of two-particle cluster approximation the transverse  piezoelectric coefficients  are calculated. The influences of hydrostatic, uniaxial pressures, shear stresses and transverse electric fields on the transverse  piezoelectric coefficients of the crystal are studied.

Calculation Method of Heat Capacity Change during Organic Compounds Vaporization and Sublimation

On the basis of literature data the constancy of heat capacity change during vaporization ( 2 %) and sublimation ( 8 %) has been determined at 298 K for different organic compounds. The obtained equations allow to recalculate the enthalpy according to Kirchhoff’s law easier compared with present techniques based on the increments method. The vaporization and sublimation enthalpies of 5-(2-nitrophenyl)-furan-2-carbaldehyde have been determined and recalculated for 298 K for the reliability proofing of the suggested method.