Sensitization of SnO2 and ZnO nanostructures by CH3NH3SnCl3 hybrid particles

With the aim of developing metal oxide nanostructures optimally designed to match the physical requirements of their applications, we tried to modify the surface of either ZnO tetrapods and SnO2 nanowires by evaporation of hybrid organic-inorganic self-assembled perovskites (surface sensitization) and investigated the resulting photoluminescence (PL) properties. Film of CH3NH3SnCl3 hybrid perovskite were thermally ablated on either ZnO tetrapods (TP) deposited on quartz substrates [see L Zanotti et al., this conference] or SnO2 nanowires (NW) grown on alumina substrates. By using a shadow mask hybrid was deposited only on one half of the ZnO TP and SnO2 NW substrates, thus leaving bare nanostructures on the other half. PL measurements were performed on the two portions of each substrate by using an excitation wavelength λ=325 nm. We observed that hybrid has negligible effects on the PL spectra of ZnO TP, but significantly modify the PL of SnO2 NWs. Bare SnO2 nanowires in fact show the usual broad featureless PL peak in the 400-600 nm range, while after hybrid deposition the peak shape is strongly modified with a slight red-shift. Since the changes of NW PL do not scale with hybrid thickness, and, on the other hand, the PL efficiency of the hybrid itself is quite modest to justify the phenomenon, we suggest that the observed effect has to be imputed to the formation of interfaces due to the interaction between the nanostructure matrix and hybrid. The mechanisms of such interaction and the consequent PL modification are presently investigated

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Taha Toros Arşivi, Dosya Adı: Nazım Hikmetİstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Composition of bacterial assemblages in different components of Reed Warbler nests and a possible role of egg incubation in pathogen regulation

Bacteria play a central role in animal health. Yet, little is known about the acquisition of bacteria and the extent to which bacteria are acquired from different environmental sources. For example, bird nests host diverse bacteria associated with the eggs, nestlings and nesting material, but previous research has typically focussed on only a limited number of nest components at a time. It therefore remains unknown to what extent bacteria are transmitted between these components. Using both molecular and culture techniques, we characterised nest-associated bacterial assemblages throughout the entire nesting cycle of reed warblers by sampling bacteria on eggs before and during incubation, within nestling faeces, and on the nesting material of post-breeding nests. We found that bacterial assemblages clustered by nest component. Yet some overlap existed between nest components, suggesting that bacterial transmission across components is likely to occur. Eggs and nestlings from the same nest harboured more similar bacteria than expected by chance, suggesting an influence of environment or genetics on bacterial assemblages. Bacterial loads were not lower on incubated eggs. Instead, incubation was associated with a change in the structure of assemblages, including a decrease in potentially-harmful Gram-negative bacteria. In addition we show for the first time, that incubation is associated with the complete extinction of harmful haemolytic bacteria. Overall, our study appears to be the first to demonstrate differences in bacterial assemblages between bird nest components. In addition, we highlight the complexity of nest bacterial assemblages and provide new insights into the benefits of incubation