The enthalpies of dilution of aqueous solutions of alkali metal and tetraalkylammonium salts of poly(thiophen-3-ylacetic acid) were determined at three temperatures and various concentrations. At low concentrations the dilution of the alkali PTAA salts yields an endothermic effect, which is in part a consequence of the hydrolysis. In the case of tetraalkylammonium salts the enthalpies of dilution increase in the order TBA ( TPA ( TEA ( TMA. When lithium salt of PTAA is mixed with LiCl, the enthalpy of mixing is positive, while it is exothermic for other alkali chlorides. On the contrary the enthalpy of mixing of lithium salt of PTAA with tetraalkylammonium salts shows strong endothermic increase with the lengthening of alkyl chain. The enthalpy of mixing values are correlated with the enthalpies of hydration of the cations of the low molecular mass salts added to the solution. This correlation is distinctively different for alkali metal and tetraalkylammonium chlorides.
COBISS.SI-ID: 1536129219
The interaction between hyaluronate anion (HA) and the lysine derived biocompatible cationic surfactant (MKM) was investigated in aqueous solutions by potentiometry and fluorescence spectroscopy. The critical micelle concentration in pure surfactant solutions and the critical association concentration in the presence of HA were determined in dependence on NaCl concentration. The equilibrium between the protonated and deprotonated forms of MKM is proposed to explain anomalous binding isotherms. The explanation is supported by the theoretical model calculations of the micellar equilibrium and the competitive binding of the two forms to the surface of the electrode membrane. The paper was chosen for graphical presentation on the Langmuir cover (volume 31, issue 48, December 8, 2015).
COBISS.SI-ID: 19020310
Article describes driving forces of binding of ligands to the human telomeric DNA sequence folded into G-quadruplex structures in relation with structural characteristics of ligands, DNA and DNA-ligand complexes, and shows how to explore the predictive power of thermodynamics for better understanding of DNA recognition of G-quadruplexes by aromatic ligands.
COBISS.SI-ID: 1536627907
The paper present a modular software MOLSIM for all-atom molecular and coarse-grained simulations. The software possesses four unique features: (1) it is an integrated software for molecular dynamics, Monte Carlo and Brownian dynamics simulations; (2) simulated objects are constructed in a hierarchical fashion representing atoms, rigid molecules and colloids, flexible chains, hierarchical polymers, and cross-linked networks; (3) long-range interactions involving charges, dipoles and/or anisotropic dipole polarizabilities are handled either with the standard Ewald sum, the smooth particle mesh Ewald sum, or the reaction-field technique; (4) statistical uncertainties are provided for all calculated observables. In addition, MOLSIM supports various statistical ensembles, and several types of simulation cells and boundary conditions are available. Intermolecular interactions comprise tabulated pairwise potentials for speed and uniformity and many-body interactions involve anisotropic polarizabilities. Intramolecular interactions include bond, angle, and crosslink potentials. A very large set of analyses of static and dynamic properties is provided. The capability of MOLSIM can be extended by user-providing routines.
COBISS.SI-ID: 1536317891
Aqueous solutions of ionene polyelectrolytes with varying chain charge density and different counterions were studied by means of neutron scattering and NMR, with emphasis on polymer backbone hydrophobicity and counterion specific effects. Experimental neutron scattering results featured a number of aspects and trends that clearly deviate from the predictions of the existing theory and points clearly to the need for combining the scaling theory concepts with those of ion specificity, to obtain a more consistent description of polyelectrolyte solutions.
COBISS.SI-ID: 1536162243