In situ determination of thickness and electrical properties of multilayers from weak polyelectrolytes.

An electro-optical study of the role that the outermost layer plays in the behavior of a multilayer film of the weak polyelectrolytes poly(acrylic acid) (PAA) and poly(allylamine hydrochloride) (PAH) was carried out. The film surface was enriched with the chains of the last adsorbed polyelectrolyte when a fully ionized polymer was combined with nearly fully charged chains of the other polyelectrolyte. A distinct influence of the chain length on the critical frequency of relaxation of the electro-optical effect was demonstrated, indicating that polarization of condensed counterions of the last adsorbed polymer governs the behavior of the whole film.

Response of rat lung to N-hexane and whole-body x-irradiation given solely or combined.

Biochemical, cytological and morphological studies in Wistar male rats. For N-hexane inhalation treatment, dynamic exposure chambers maintaining a concentration of 5,500 mg/m3 over 5 hours per day were used for 8 days. Immediately there after, the animals were given a single whole-body exposure to 4 Gy X-rays.