A Raman Study of Titanate Nanotubes

The effect of the addition of NaOH or KOH on commercial Degussa Titania P25 was investigated using TEM, Raman and in situ Raman spectroscopy. Treatment of titania with conc. NaOH generated a tubular material corresponding to a sodium titanate. An in situ Raman study on the sodium titanate nanotubes as a function of temperature revealed that the titanate structure was stable up to 700°C.Ramanspectra of the titanate nanotubes after acid treatment, showed that the titanate structure was retained andEDX analysis revealed only trace amounts of sodium (0.3%) left in the material. HRTEM data are also consistent with the synthesis of protonated titanate nanotubes. An in situ Raman study of protonated titanate nanotubes as a function of temperature showed that the material was stable up to 150°C, while anatase appeared at T > 300°C. An in situ Raman study of the protonated titanate nanotubes produced from KOH as a function of temperature showed that the shape and size of the nanotubes prepared from NaOH and KOH are similar although rutile formation at 1000°C was different. A proposal for the formation of tubular titanates (and anatase) is given.Keywords: Titania nanotubes, titanate nanotubes, in situ Raman spectroscopy, HRTEM

Patterns of prey selection of Trypoxylon (Trypargilum) lactitarse Saussure (Hymenoptera: Crabronidae) in southern Brazil

This study was carried out in the Parque Municipal das Araucárias, in the municipality of Guarapuava, southern Brazil. A total of 449 T. lactitarse nests were collected using trap-nests of different diameters. Fifty three species of spiders belonging to 7 families were captured by T. lactitarse. Araneidae was the most captured family and has been strongly represented by the genus Eustala. Through Bray-Curtis's coefficient and the unweighted pair group method average (UPGMA), the spiders species can be divided into 3 groups: the smaller group includes the most abundant species (Eustala sp1, Eustala sp2, Acacesia villalobosi, Alpaida sp1 and Araneus corporosus), the second group includes species with intermediate abundance (Wagneriana iguape, Araneus omnicolor, Eustala sp4, Alpaida grayi, Eustala sp3, Larinia t-notata, Mangora sp1 and Wagneriana iguape), and the third and largest group includes the least abundant species (Aysha gr. brevimana 1, Eustala sp5, Wagneriana eupalaestra, Alpaida scriba, Alpaida veniliae, Araneus aff. omnicolor, Araneus sicki, Eustala sp8, Mangora sp2, Mangora sp3, Wagneriana juquia, Alpaida sp2, Araneus blumenau, Eustala sp6, Eustala sp7 and Ocrepeira galianoae). Of 2,029 identified spiders, 1,171 were captured in the Araucaria forest, 612 in grassland areas and 246 in the swamp. Grassland and swamp areas evidenced greater similarity between them than to the Araucaria Forest, regarding presence-absence of spider species in T. lactitarse's diet, as well as regarding species abundance in these habitats. The juvenile number (56%) was significantly higher than the female (38%) and male (6%) percentages

The Tracking, calorimeter and muon detectors of the H1 experiment at HERA

Technical aspects of the three major components of the H1 detector at the electron-proton storage ring HERA are described. This paper covers the detector status up to the end of 1994 when a major upgrading of some of its elements was undertaken. A description of the other elements of the detector and some performance figures from luminosity runs at HERA during 1993 and 1994 are given in a paper previously published in this journal.0400 auteursSCOPUS: ar.jinfo:eu-repo/semantics/publishe