Encontrados 41 documentos, a visualizar página 1 de 5
A low-noise CMOS front-end for TOF-PET
Rolo, M. D.; Alves, L. N.; Martins, E. V.; Rivetti, A.; Santos, M. B.; Varela, J.An analogue CMOS front-end for triggering and amplification of signals produced by a silicon photomultiplier (SiPM) coupled to a LYSO scintillator is proposed. The solution is intended for time-of-flight measurement in compact Positron Emission Tomography (TOF-PET) medical imaging equipments where excellent timing resolution is required (approximate to 100 ps). A CMOS 0.13 mu m technology was used to implement ...
Microplate-based high throughput screening procedure for the isolation of lipid...
Pereira, Hugo; Barreira, Luísa Paula Viola Afonso; Mozes, Andre; Florindo, C.; Polo, Cristina; Duarte, Catarina V; Custódio, Luísa Margarida BatistaAbstract We describe a new selection method based on BODIPY (4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene) staining, fluorescence activated cell sorting (FACS) and microplate-based isolation of lipid-rich microalgae from an environmental sample. Our results show that direct sorting onto solid medium upon FACS can save about 3 weeks during the scale-up process as compared with the growth of the...
First isotopic records from stalagmites in Algarve (South Portugal)
Veiga-Pires, C.; Moura, Delminda; Luis, Joaquim; Varela, J.; Ghaleb, Bassam; Hélie, Jean-François; Hillaire-Marcel, C.Os espeleotemas representam registos paleoclimáticos continentais de alta resolução e estão a ser cada vez mais estudos para fins de reconstrução climática de períodos não afectados por acções antropogénicas. Na região do Algarve (Sul de Portugal), a existência de formações carbonatadas do Jurássico e Cretácico permitiu um desenvolvimento de sistemas cársicos onde se encontram actualmente estruturas estalagmíti...
Analysis of Ca-PZT powder obtained by the Pechini and partial oxalate methods
Nasar,R. S.; Cerqueira,M.; Longo,E.; Varela,J. A.Ca-Pb(Zr,Ti)O3 (Ca-PZT) powders were prepared by a combined method, Pechini technique for the intermediate ZrTiO4 (ZT) particles and oxalate route for the final powder. The intermediate and final products were characterized by X-ray diffraction and BET for phase identification and granulometric analysis, respectively. The surface area of ZT powder reduced remarkably from 70 to 7.4 m²/g when the calcining temper...
Materiais cerâmicos de inserção aplicados a baterias de íons lítio
Pesquero,N. C.; Bueno,P. R.; Varela,J. A.; Longo,E.Esta revisão visa ser uma introdução à aplicação de materiais cerâmicos em dispositivos de armazenamento de energia, em especial baterias secundárias de íons lítio, dispositivos nos quais os materiais cerâmicos, especialmente óxidos, são muito importantes em todas as partes do dispositivo. A revisão está focada nos materiais cerâmicos para catodos e anodos, partes chaves destes dispositivos. Ela tem por princip...
Characterization of Dunaliella salina strains by flow cytometry: a new approach...
Mendoza, Hector; de la Jara, Adelina; Freijanes, Karen; Carmona, Laura; Ramos, Ana; Duarte, Vanessa; Varela, J.In the present work the characterization of different strains of Dunaliella salina from established cell culture collections and various isolates from solar saltworks located in the Canary Island, as well as one mutant, was carried out in order to assess the existence of intraspecific differences and to determine the potential productivity of each one. Morphological characteristics such as cellular size and cel...
Evolutionary origins and functions of the carotenoid biosynthetic pathway in ma...
Coesel, Sacha; Obornik, Miroslav; Varela, J.; Falciatore, Angela; Bowler, ChrisCarotenoids are produced by all photosynthetic organisms, where they play essential roles in light harvesting and photoprotection. The carotenoid biosynthetic pathway of diatoms is largely unstudied, but is of particular interest because these organisms have a very different evolutionary history with respect to the Plantae and are thought to be derived from an ancient secondary endosymbiosis between heterotroph...
Clear-PEM: A PET imaging system dedicated to breast cancer diagnostics
Abreu, M. C.; Aguiar, D.; Albuquerque, E.; Almeida, F. G.; Almeida, P.; Amaral, P.; Auffray, E.; Bento, P.; Bruyndonckx, P.; Bugalho, R.; Carriço, B.The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A sp...
Photoluminescence in ZrO2 doped with Y and La
Sousa,W. S. C. de; Melo,D. M. A.; Silva,J. E. C. da; Nasar,R. S.; Nasar,M. C.; Varela,J. A.This study aims to describe the synthesis and optical characterization of a nanometric zirconium oxide solid solution containing yttrium and lanthanum. Zirconium citrate, yttrium nitrate and lanthanum nitrate were mixed in the ratios: 94 mol% of ZrO2 - 6 mol% of Y2O3 and 92 mol% of ZrO2 - 6 mol % of Y2O3 - 2 mol % of La2O3. FTIR analysis shows organic material in decomposition and thermal analysis shows the tra...
Influência de dopantes doadores na degradação do varistor à base de SnO2 e o ef...
Oliveira,M. M.; Rangel,J. H. G.; Sousa,V. C. de; Leite,E. R.; Longo,E.; Bueno,P. R.; Varela,J. A.A degradação elétrica de varistores à base de SnO2 foi estudada e verificou-se que na temperatura de 220 ºC ocorreu a degradação do material. Suas características foram recuperadas quando tratadas em atmosfera de O2, o que mostra que esta atmosfera é fundamental para a característica do varistor.
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