Isotopic effect on the aging dynamics of a charged colloidal system

A dynamic light scattering (DLS) investigation of the isotopic H/D substitution on water molecules in aqueous Laponite suspensions is reported for two Laponite weight concentrations (C-w = 1.5% and C-w = 3.0%). Increasing the deuterium percentage results in a slowing down of the dynamics for both concentrations, although the aging behavior of the suspensions is not qualitatively modified by the isotopic substitution. A scaling law for the isotopic effect is found. The relaxation times and the stretching parameters collapse on two distinct master curves, indicating that the two previously found dynamical behaviors of colloidal gels and glasses are preserved. These results may facilitate a large variety of experimental techniques and further theoretical investigations about the role of the solvent in determining the interaction potential

Firing technique characterization of black-slipped pottery in Praeneste by low field 2D NMR relaxometry

This study was aimed at individuating characteristics related to the pottery's firing technique of Classical Roman producers, through the low field single-sided NMR relaxometry. The approach is based on a recent method of analysis, the correlation of the longitudinal and transverse NMR relaxation times of a liquid probe (in this case distilled water) filling the porous system of ceramics. The analyzed findings form two homogeneous classes with dating and place of production well established through the producer trademarks. Pottery findings belong to the black-slipped pottery productions of the Latin ancient city of Praeneste between third and second century B.C. and have been attributed to two different " patriziae" production families: gens Samiaria and gens Trebonia. A further fragment with Greek kylix style, found in the same archaeological area, has also been analyzed, in order to understand if it had been imported from Greece, or made in Praeneste in imitation of the Greek style

The structure of water near a charged crystalline surface

The structure of water near a synthetic clay surface, Laponite, is probed experimentally by total neutron scattering, in both liquid and arrested states. It is shown that the crystalline structure of the Laponite platelets and their charge distribution determine polarization of the closest water layers, with a local density higher than that of bulk water. Interestingly these layers show long range order in the plane parallel to the Laponite surface, while no indication of strong hydrogen bonding between water and Laponite is found

Movement abnormalities in the left ventricle of thalassemia major patients

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