Browsing by Author "Silva, C."
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- Global volatile profile of virgin olive oils flavoured by aromatic/medicinal plantsPublication . Perestrelo, R.; Silva, C.; Silva, P.; Câmara, J. S.The global volatile profile of commercial virgin olive oils and flavoured olive oils with aromatic/medicinal plants, was established using liquid-liquid microextraction (LLME) and headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-quadrupole mass spectrometry (GC-qMS). More than 60 volatile organic compounds (VOCs belonging to different groups were identified using both methods. Olive oils volatile profile was slightly influenced by maceration process, which occurred at room temperature (20±2°C) for 15days. The predominant differences were observed in terpenoids group, since some of them were only identified in the flavoured olive oils, while others showed an increase with the maceration process. VOCs mass transfer from plants to olive oils could explain the observed results. Principal components analysis (PCA) applied to LLME/GC-qMS data allowed to distinguish the olive oils. The flavoured oils would increase the use of olive oil among consumers as consequence of the improvement of its aromatic profile and healthy properties.
- Numerical simulation of the initial stage of unipolar arcing in fusion-relevant conditionsPublication . Kaufmann, H. T. C.; Silva, C.; Benilov, M. S.A model for the initial phase of unipolar arcing has been developed with account of an external energy source which triggers the arcing, the vaporization of the atoms from the heated surface, the ions and electrons produced by ionization of the vapor, the electron emission from the metal surface, and melt motion and surface deformation. Current transfer outside the arc attachment is taken into account and the potential difference between the plasma and the metal surface (the plate) is evaluated from the condition that the net current transferred to the plate is zero at each moment. The model is used for simulation of the interaction of an external energy load (laser beam) with a tungsten plate immersed in a helium background plasma. The results revealed the formation of a crater, but no jet formation or droplet detachment. If the plate is large (R = 100 mm), the peak temperature attained is 5200 K, and the plate potential remains below the plasma potential. If the plate is small (R = 10 mm), a peak temperature of 7500 K is reached, the potential of the plate surpasses the plasma potential, circulation of the melt at the pool periphery occurs, and the erosion (which is mainly due to the vaporization of the metal atoms in the spot) reaches the value of 37 μg.
- Skeletal maturity and socio-economic status in portuguese children and youths: the Madeira growth studyPublication . Freitas, Duarte Luís de; Maia, José António Ribeiro; Beunen, Gaston Prudence; Lefevre, Johan Aimé; Claessens, Albrecht Leo; Marques, A.; Rodrigues, A.; Silva, C.; Crespo, Maria; Thomis, Martine Ann; Sousa, A.; Malina, Robert M.Skeletal maturity is used to evaluate biological maturity status. Information about the association between socio-economic status (SES) and skeletal maturity is limited in Portugal. Aims: The aim of this study is to document the skeletal maturity of youths in Madeira and to evaluate variation in maturity associated with SES. Subjects and methods: The study involved 507 subjects (256 boys and 251 girls) from the Madeira Growth Study, a mixed-longitudinal study of five cohorts (8, 10, 12, 14 and 16 years of age) followed at yearly intervals over 3 years (1996–1998). A total of 1493 observations were made. Skeletal age was estimated from radiographs of the hand and wrist using the Tanner–Whitehouse 2 method (TW2). Social class rankings were based on Graffar’s (1956) method. Five social rankings were subsequently grouped into three SES categories: high, average and low. Results: Median for the radius, ulna and short finger bones (RUS scores) in the total sample of boys and girls increased curvilinearly across age whereas median for the 7 (without pisiform) carpal bones (Carpal scores) increased almost linearly. The 20-bone maturity scores demonstrated distinctive trends by gender: the medians for boys increased almost linearly while the medians for girls increased curvilinearly. SES differences were minimal. Only among children aged 10–11 years were high SES boys and girls advanced in skeletal maturity. Madeira adolescents were advanced in skeletal maturity compared with Belgian reference values. Conclusion: The data suggests population variation in TW2 estimates of skeletal maturation. Skeletal maturity was not related to SES in youths from Madeira.