Communication: Relationships between Intermolecular potential, thermodynamics, and dynamic scaling in viscous systems.

In this communication, we provide a recipe for a consistent relation between dynamic scaling and thermodynamic properties well-grounded by the same intermolecular generalized Lennard-Jones potential, which is derived by using an essentially modified Avramov model within the framework of the "thermodynamic scaling" idea. This relation is experimentally verified very well for supercooled van der Waals liquids, and consequently, it can be a good basis for a proper universal description of molecular dynamics and thermodynamics of viscous systems.

Density scaling of supercooled simple liquids near the glass transition.

In this work, we show that two competing equations of state, the first one derived from some effective approximation of intermolecular potential suspected to be responsible for so-called "thermodynamic scaling" and the second one following from the definition of isothermal bulk modulus, are able to describe very well experimental volumetric data of supercooled van der Waals liquids in the thermodynamic scaling regime. The values of the exponent gamma(EOS) experimentally established from both these equations of state are numerically very close, and moreover they enable us to achieve a high quality of the specific volume or density linear scaling suggested by these equations. However, the found density scaling requires a distinctly different value of gamma(EOS) than that leading to the scaling of dynamic quantities. The discrepancy can be explained by our modification of the Avramov model which assumes the density scaling of the maximal energy barrier with the scaling exponent gamma(EOS).

Kinetic processes in supercooled monosaccharides upon melting: Application of dielectric spectroscopy in the mutarotation studies of D-ribose.

Dielectric spectroscopy has been recently used to monitor mutarotation in undercooled D-fructose. This method can be viewed as a universal method to study mutarotation phenomenon in the whole family of monosaccharides. In this paper, we studied kinetics of mutaration of anhydrous D-ribose at ambient pressure as well as pressure effect on the rate constant of this process. Ribose mutarotation behavior is compared to the one obtained for D-fructose. In addition, we attempted to determine the "direction" of mutarotation in undercooled monosaccharides after quenching the melted sample. To this end, analysis of dipole moments of different tautomers of D-fructose and D-ribose have been performed. Conformational analysis of studied carbohydrates was done with use of density functional theory. Geometry optimizations as well as calculations of dipole moments were done on the 6-311++G(d,p)/B3LYP level. Finally, it turned out that data obtained from the mutarotation experiment might be helpful in understanding the origin of gamma-process occurring in the whole family of carbohydrates.