Performances hydration shorts

Cui et al. performed similar analyses to fhose of Dupuis and co-workers. The side chain-side chain radial disfribufion functions (RDFs) reported by Cui et al. show remarkable qualitative deviation from fhose in Zhou et al. i It is of note that the united atom approach used by Cui and co-workers ignored electrostatic interactions between CP2 groups of the polymeric backbone. This can lead to a poor description of fhe hydrated structure in the regions close to the polymeric backbones, unlike the all-atom force field used in Zhou et al. ° For the sake of limited computational resources, Cui et al. used a relatively short representation of Nation ionomer chains consisting of three monomers as compared to the ten monomers used by Vishnyakov and Neimark or Urata et al. It can be expected that structural correlations will strongly depend on this choice. 

Aging studies, performed in the laboratory, are useful for confirming theoretical models describing the behavior of the object at short-, medium-, and long-term intervals. Formed alteration products, (e.g., by oxidation, reduction, polymerization, scission, hydration, dehydration, dehydrogenation, etc.) are the target compounds in such studies. Three-dimensional (3D) diagrams can be built from the spectra or other characteristic curves obtained at different times. 

It has been possible to describe the short time diffusion (a few picoseconds) of water molecules close to a hydrophilic surface in terms of simple models [70] for all of the studied samples. At short times, the water molecules close to some hydrophilic surface perform very local rotational jumps characterized by D and x, like in bulk water but with a longer residence time Xq on a given site before diffusing to an adjacent site along the surface with a diffusion coefficient equal to locai diffusion is limited to some volume estimated as spherical. For the 25% hydrated sample, the diffusion coefficient measured by NMR appears to be smaller than Dj which is smaller than [71 ]. This is due to the fact that NMR... 

Most of the preparations of aluminas are performed by thermal decomposition of alumina hydrates (i.e., hydroxides, oxyhydroxides) previously precipitated from solutions containing Al " ions or organometaUic compounds. The characteristics of the obtained aluminas are closely related to those of the hydrate precursor. Thus, a short review of the structural characteristics of these compounds and of the conditions for their precipitation will be given in Sections 2.1.1 to 2.1.3. 

Cui and co-workers performed classical molecular-dynamics simulations of two dilferent perfluorosulfonic-acid (PFSA) membranes to investigate the hydrated morphology and the hydronium-ion dilfusion. They put special emphasis on the water content of the membrane (5% to 20%) and compared the properties for two dilferent lengths of the side chains carrying the sulfonic-acid groups. The short side chains lead to a more disperse distribution of water clusters inside the membrane. At low water content this results in a more connected water-channel network, which enhances the proton transport. 

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