Navegando por Autor "Leite, Cristiano Fantini"
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Item A new appraisal of sri lankan bb zircon as a reference material for LA-ICP-MS U-Pb geochronology and Lu-Hf isotope tracing.(2017) Santos, Maristella Moreira; Lana, Cristiano de Carvalho; Buick, Ian S.; Schmitz, Mark D.; Kamo, Sandra L.; Gerdes, Axel; Corfu, Fernando; Tapster, Simon; Lancaster, Penelope; Storey, Craig Darryl; Basei, Miguel Ângelo Stipp; Tohver, Eric; Alkmim, Ana Ramalho; Nalini Júnior, Hermínio Arias; Krambrock, Klaus Wilhelm Heinrich; Leite, Cristiano Fantini; Wiedenbeck, MichaelA potential zircon reference material (BB zircon) for laser abla tion-in ductively coupled plasma-mass spectrometry (LA-ICP-M S)U-Pb geochronology and Hf isotope geochemistry is described. A batch of twenty zircon megacrysts (0.5–1.5 cm3) from SriLanka was studied. Within-grain rare earth element (REE) compositions are largely homogeneous, albeit with somevariation seen between fractured and homogeneous domains. Excluding fractured cathodoluminescence bright domains,the variation in U content for all analysed crystals ranged from 227 to 368 lgg-1and the average Th/U ratios werebetween 0.20 and 0.47. The Hf isotope composition (0.56–0.84 g/100 g Hf) is homogeneous within and between thegrains – mean176Hf/177Hf of 0.281674 ± 0.000018 (2s). The calculated alpha dose of 0.59 3 1018g-1for a numberof BB grains falls within the trend of previously studied, untreated zircon samples from Sri Lanka. Aliquots of the samecrystal (analysed by ID-TIMS in four different laboratories) gave consistent U-Pb ages with excellent measurementreproducibility (0.1–0.4% RSD). Interlaboratory assessment (by LA-ICP-MS) from individual crystals returned results that arewithin uncertainty equivalent to the TIMS ages. Finally, we report on within- and between-grain homogeneity of theoxygen isotope systematic of four BB crystals (13.16‰ VSMOW).Item Uso de nanobastões de ouro para o desenvolvimento de aulas práticas de nanotecnologia.(2017) Ferreira, Cyntia Silva; Ladeira, Luiz Orlando; Leite, Cristiano Fantini; Fonseca, Flávio Guimarães da; Ribeiro, Erica Milena de Castro; Versiani, Alice Freitas; Silva, Jorge Fernando de Souza; Magalhães, Cíntia Lopes de Brito; Silva, Breno de MelloUse of gold nanoparticles functionalization experiment was conducted in a biotechnology summer course at UFOP as a model for the introduction of the laboratory practice in nanotechnology for postgraduate courses in the areas of chemistry and biotechnology. The gold nanorods were synthesized by the seed method and then, functionalized with anti-IL-6 antibodies using the reagents EDAC/NHS and polyethyleneimine (PEI). This nanocompound was tested against the binding with the specific antigen (IL-6) and changes in the longitudinal plasmon absorption spectrum showed the coupling efficiency, which was also verified by the decrease in zeta potential. The experiment was satisfactory, with a positive feedback from participants, and could be implemented in nanotechnology practical classes from postgraduate courses, as a way for improve education in the emergent area of nanobiotechnology.