Revealing fast proton transport in condensed matter by means of density scaling concept

Herein, we investigate the charge transport and structural dynamics in the supercooled and glassy state of protic ionic material with an efficient interionic Grotthuss mechanism. We found that superprotonic properties of studied acebutolol hydrochloride (ACB-HCl) depend on thermodynamic conditions with the most favorable regions being close to the glass-transition temperature (Tg) and glasstransition pressure (Pg). To quantify the contribution of fast proton hopping to overall charge transport over a broad T−P space, we employed the density scaling concept, one of the most important experimental findings in the field of condensed matter physics. We found that isothermal and isobaric dc-conductivity (σdc) and dynamic light scattering (τα) data of ACB-HCl plotted as a function of (TVγ)−1 satisfy the thermodynamic scaling criterion with the ratio γσ/γα appearing as a new measure of fast charge transport in protic ionic glass-formers in the T−P plane. Such a universal factor becomes an alternative to the well-known Walden rule being limited to ambient pressure conditions

Hydrodynamic Properties of Micelles of Dihydroxy Bile Salts: Sodium Taurodeoxycholate and Sodium Glycodeoxycholate

The dependence of the mutual translational diffusion coefficient and the sedimentation coefficient on concentration of sodium taurodeoxycholate in aqueous 0.15 m NaCl solutions at 25 °c indicates a pronounced increase of the micelle size in the region between the critical micelle concentration, equal to 0.00082 gcm-3, and approximately ten times higher concentration. These results were substantiated by the variation of the Rayleigh ratio of scattered light. At concentrations of bile salt higher than about 0.008 gcm-3 the hydrodynamic and the thermodynamic interactions dominate the measured quantities. The quasielastic light scattering measurements provided the estimates of the polydispersity of the micelles. The diffusion coefficient of sodium glycodeoxycholate varied with concentration in a manner similar to that for the taurine conjugate

Freezing lines of colloidal Yukawa spheres. II. Local structure and characteristic lengths

Using the Rogers-Young (RY) integral equation scheme for the static pair correlation functions combined with the liquid-phase Hansen-Verlet freezing rule, we study the generic behavior of the radial distribution function and static structure factor of monodisperse charge-stabilized suspensions with Yukawa-type repulsive particle interactions at freezing. In a related article, labeled Paper I [J. Gapinski, G. Nägele, and A. Patkowski, J. Chem. Phys.136, 024507 (2012)], this hybrid method was used to determine two-parameter freezing lines for experimentally controllable parameters, characteristic of suspensions of charged silica spheres in dimethylformamide. A universal scaling of the RY radial distribution function maximum is shown to apply to the liquid-bcc and liquid-fcc segments of the universal freezing line. A thorough analysis is made of the behavior of characteristic distances and wavenumbers, next-neighbor particle coordination numbers, osmotic compressibility factor, and the Ravaché-Mountain-Streett minimum-maximum radial distribution function ratio

The effect of mono- and divalent cations on Tetrahymena thermophila telomeric repeat fragment. A photon correlation spectroscopy study.

The structure of the Tetrahymena thermophila telomeric sequence d(TGGGGT)4 was studied by photon correlation spectroscopy (PCS) in aqueous solution in the presence of NaCl, KCl and SrCl2. The sample studied was polydisperse in all conditions studied. Translational diffusion coefficients DT describing the diffusion modes observed were determined. On the basis of a comparison between the experimental DT values with those calculated assuming the bead model, two forms were identified as telomeric quadruplex structures: monomer and tetramer. In the presence of SrCl2 formation of aggregates was observed, with a size that reached several micrometres. The relative weighted concentrations of the structures observed for different concentrations of a salt and DNA were determined. The results obtained in the presence of monovalent ions were qualitatively similar and could be presented in a coherent plot in which the concentration of salt was expressed by the number of ions per DNA molecule. A large number of ions per DNA molecule favoured tetramer formation while a small number favoured the monomer form. A structural phase transition from the monomer to the tetramer induced by a change in the number of ions per DNA molecule was observed. The main difference between the results for Na+ and K+ was a greater effectiveness of the K+ ions in formation of tetramers. The effect of Sr2+ ions on the structures formed was different than that of the monovalent ions. The results obtained in the presence of Sr2+ could not be described as a function of the number of ions per DNA molecule