We show that first approximations to the bulk viscosity ηv are expressible in terms of factors that depend on the sound speed vs, the enthalpy, and the interaction (elastic and inelastic) cross section. The explicit dependence of ηv on the factor ( 1 3 − v 2 s ) is demonstrated in the ChapmanEnskog approximation as well as the variational and relaxation time approaches. The interesting feature ...

Here, we show that a new class of glasses composed of heavy metal oxides involving transition metals (V2O5-TeO2) can surprisingly be designed from very basic tools using topology and rigidity of their underlying molecular networks. When investigated as a function of composition, such glasses display abrupt changes in network packing and enthalpy of relaxation at Tg, underscoring presence of fle...

Amorphous silicon nitride is a model system for a covalently bound amorphous solid with a low atomic mobility where reasonable values of self-diffusivities are still lacking. We used neutron reflectometry on isotope enriched Si3 14N4/Si3 15N4 multilayers to determine nitrogen self-diffusivities ranging from 10(-24) to 10(-21) m2/s between 950 and 1250 degrees C. Time dependent diffusivities obs...

The in-plane (plane stress) fracture toughness of two polyester (PET, PETG) sheets were assessed using the essential work of fracture (EWF) method after thermal and hygrothermal aging performed just below glass temperature. This ensured that physical aging takes place. On the aged sheets the yield stress (σy), enthalpy relaxation (ΔH) and EWF parameters were determined. It was observed that the...

Thermophysical bases of vitrification and crystallization are discussed in terms of the enthalpy versus temperature diagram and its derivative (DTA) illustrating relaxation and glass transformation as well as crystallization of glassy and amorphous states to form stable and metastable phases. Non-isothermal kinetics are thoroughly discussed and the use of one(JMAEK) and two(SB) parameter equati...

Current Isothermal Titration Calorimetry (ITC) data in the literature have relatively high errors in the measured enthalpies of protein-ligand binding reactions. There is a need for universal validation standards for titration calorimeters. Several inorganic salt co-precipitation and buffer protonation reactions have been suggested as possible enthalpy standards. The performances of several com...

During the past year the activities of the Chemical Thermodynamics Data Center and the JANAF Thermochemical Tables project have been combined to obtain an extensive collection of thermodynamic information for many chemical species, including the elements. Currently available are extensive bibliographic collections and data files of heat capacity, enthalpy, vapor pressure, phase transitions, etc...

We show that the relaxational dynamics as exhibited in the enthalpy relaxation of the density wave compounds at very low temperatures (T<lK) is very similar to that one occuring in disordered systems such as glassy polymers or spin glasses. We discuss these similarities, as well as some pecularities, in the frame of secondary relaxational processes as genuine features of glass formers below the...

The jump frequency of Cd tracer atoms in pure and Al-doped β-Mn was determined from measurements of quadrupole relaxation using the method of perturbed angular correlation of gamma rays. The jump frequency of Cd in β-Mn containing about 4.5 at.% Al had an activation enthalpy of 0.67(3) eV. In pure β-Mn at 950 K, the jump frequency was a factor about 8 larger than the value of 9.2 MHz in the all...