RESUMO
The dependences of cathodoluminescence (CL) from ZnO:Zn phosphor powder upon local space, accelerating voltage and beam current have been investigated at room temperature. Ultraviolet (UV) luminescence, which is hard to be observed in photoluminescence (PL) at room temperature, has been clearly observed in CL as well as green luminescence. The intensity ratio of the UV luminescence to the green one varies from point to point. From the comparison with PL, the UV luminescence is attributed to the recombination of ZnO free excitons. The UV luminescence is little observed at low accelerating voltage where, similar to the excitation light for PL measurement, the electron beam penetrates into only the surface depletion layer where free excitons are unstable due to the surface electric field. However, the UV luminescence from the depletion layer becomes observable at large beam current because of the suppression of the electric field in the depletion layer caused by injected electrons.
RESUMO
The aim of this study was to use n-3 fatty acid-deficient pregnant mice to assess maternal behavior in the perinatal period. Female mice were fed either an n-3 fatty acid-deficient (n-3 Def) or -adequate (n-3 Adq) diet for two generations. The nest score and volume of the n-3 Def dams were lower than those of the n-3 Adq dams. In the observation of the post-delivery conditions, 40% of the n-3 Def dams attacked their newborns or did not nurse them. The brain docosahexaenoic acid (DHA) levels of the n-3 Def dams were lower than those of the n-3 Adq dams. In the hippocampus, moreover, positive correlations were observed between the DHA and the 5-HT or 5-HIAA, and a negative correlation was observed between the DHA and the DA. These results suggest that dietary n-3 fatty acids may normalize the development of maternal behavior and prevent postpartum depression.