By using density functional theory on [FeFe]-hydrogenase mimics we deconvolute the function of pendant amine bases in proton transfer to and from the metal center. By dividing the high free energy barrier into one high enthalpy-low entropy barrier and one with a low enthalpy-high entropy, a lower free energy barrier is reached.

Metformin is one of the important anti-diabetic drugs to treat non-insulin dependent diabetes mellitus (NIDDM). Fourier transform infrared (FTIR) and Fourier transform Raman (FTR) spectra of metformin have been used for the molecular study. A satisfactory band assignment has been made on the fundamental modes of vibration. Employing the molecular mechanics method using MM3 force field, the theo...

Chemical composition of interfaces—free surfaces and grain boundaries—is generally described by the Langmuir–McLean segregation isotherm controlled by Gibbs energy of segregation. Various components of the Gibbs energy of segregation, the standard and the excess ones as well as other thermodynamic state functions—enthalpy, entropy and volume—of interfacial segregation are derived and their phys...

This paper presents an application of plastic evolu tion to design a new chemical index (the coordination index , ( .) that permits molecular characterizati on. Ie is applied to homologous series of phenyl alcohols and 4-alkylanilines. and compared to charge indices for dipole mome nt. The parameters needed to calcu late Ie are minus the standard enthalpy of formation T, molecu lar surface area...

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...

Standard enthalpies of formation of ternary phases in the Cu-Ni-Sn system were determined along sections at 25, 41 and 45.5 at.% Sn applying tin solution drop calorimetry. Generally, the interaction of Ni with Sn is much stronger than that of Cu with Sn. Along all sections the enthalpy of formation changes almost linearly with the mutual substitution of Cu and Ni within the respective homogenei...

The enthalpy relaxation behavior of Ti41.5Cu37.5Ni7.5Zr2.5Hf5Sn5Si1 bulk metallic glass (BMG) was investigated in this study. It is found that relaxation behavior follows the general characteristics for amorphous materials: the annealing time dependence of recovery enthalpy follows a stretched exponential function with the mean relaxation time obeying an Arrhenius law. In addition, the equilibr...

In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models...

The goal of this study is to use the model system described earlier to make direct measurements of the enthalpy of helix formation at different temperatures. For this we studied model alanine peptides in which helix formation can be triggered by metal (La(3+)) binding. The heat of La(3+) interaction with the peptides at different temperatures is measured by isothermal titration calorimetry. Cir...