Electronic And Structural Study Of Pt-modified Au Vicinal Surfaces: A Model System For Pt-au Catalysts.

Two single crystalline surfaces of Au vicinal to the (111) plane were modified with Pt and studied using scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS) in ultra-high vacuum environment. The vicinal surfaces studied are Au(332) and Au(887) and different Pt coverage (θPt) were deposited on each surface. From STM images we determine that Pt deposits on both surfaces as nanoislands with heights ranging from 1 ML to 3 ML depending on θPt. On both surfaces the early growth of Pt ad-islands occurs at the lower part of the step edge, with Pt ad-atoms being incorporated into the steps in some cases. XPS results indicate that partial alloying of Pt occurs at the interface at room temperature and at all coverage, as suggested by the negative chemical shift of Pt 4f core line, indicating an upward shift of the d-band center of the alloyed Pt. Also, the existence of a segregated Pt phase especially at higher coverage is detected by XPS. Sample annealing indicates that the temperature rise promotes a further incorporation of Pt atoms into the Au substrate as supported by STM and XPS results. Additionally, the catalytic activity of different PtAu systems reported in the literature for some electrochemical reactions is discussed considering our findings.

A moradia estudantil universitária como tema na produção científica nacional

This study analyses the national scientific production about college students' residence halls. The country's main data bases and electronic sites of several Brazilian higher education institutions were checked and 23 studies, published between 2000 and 2009, were found. The results of our analysis point to different focuses, which can be grouped into three categories: students who live in residence halls, residence halls themselves and actions for student assistance. Although there is large foreign scientific production about college student housing, the national production on this theme is still scarce, and the idea of student residence halls as educational spaces is still very incipient. The study points out to the need for investigating the living conditions in these places, and the impacts of this kind of habitation on students. Considering that student housing is an institutional responsibility, these studies potentially subsidize measures for proper educational conditions for college students.

Comparação da associação de diferentes programas de atividade física aplicados no local de trabalho sobre o nível de atividade física e qualidade de vida de trabalhadores do setor administrativo de comunidade universitária

Universidade Estadual de Campinas . Faculdade de Educação Física