Mathematical analysis and simulation of a discontinuous rectification column was performed using an operational strategy during the start-up before reaching pseudo-stable state in operation. The mathematical model formulated focusing on equilibrium (ES) implementing MESH equations (M: Mass balance, E: Equilibrium thermodynamics, S: Stoichiometry relations, H: Enthalpy or heat balance) to provid...

using gaussian 03, software the thermodynamic functions such as gibbs free energy, g, enthalpy, h, and entropy, s, of alanine and valine amino acids were theoretically studied at different solvents. first, the density functional theory (b3lyp) level with 3-21g, 6-31g and 6-31+g basis sets were employed to optimization of isolated alanine and valine amino acids in the gas phase. moreover, vib...

Molecular dynamics simulations of bulk copper, gold pure metals and their ordered intermetallics alloys of Cu3Au(L12) and CuAu3(L12) have been carried out between above 0 K and below the their melting points of the materials for predicting their temperature-dependent thermophysical properties. The effects of temperature and concentration on the physical properties such as enthalpy, volume, heat...

We report a thermodynamic and structural analysis of six extensively simplified bovine pancreatic trypsin inhibitor (BPTI) variants containing 19-24 alanines out of 58 residues. Differential scanning calorimetry indicated a two-state thermal unfolding, typical of a native protein with densely packed interior. Surprisingly, increasing the number of alanines induced enthalpy stabilization, which ...

Many empirical parameters have been suggested to measure solvent effects in chemical reactions. Gutmann's donor number has been a successful parameter to quantify the electron-donating property of the solvent molecule; it is defined as the enthalpy change of the addition reaction of solvent molecule to SbCl(5) in 1,2-dichloroethane. Calorimetric measurements can be applied to determine the qu...

Hydration free energies are dictated by a subtle balance of hydrophobic and hydrophilic interactions. We present here spectroscopic approach, which gives direct access to the two main contributions: Using THz-spectroscopy probe frequency range intermolecular stretch (150–200 cm−1) hindered rotations (450–600 cm−1), local contributions due cavity formation interactions can be traced back. show t...

The solvation of alanine is investigated, with a focus on adding a sufficient number of discrete water molecules to determine the first solvation shell for both the nonionized (N) and zwitterionic (Z) forms to converge the enthalpy of solvation and the enthalpy difference for the two forms of alanine. Monte Carlo sampling was employed using the generalized effective fragment potential (EFP) met...

The interaction between bovine serum albumin (BSA) and methyl cinnamate (MC), an strawberry flavor compound, was investigated. We found that BSA and MC form complex with stoichiometry (n) equal 1, driven by system’s entropy increase and enthalpy reduce at pH 7.4, 5.0 and 3.5, with binding constants (Kb) in magnitude of 10 5 L.mol -1 . There was difference in variation of standard enthalpy of co...