The composition of zircon in peraluminous Variscan granites from Northern Portugal.

A group of slightly peraluminous Variscan plutons in Northern Portugal were selected from the study of zircon composition. The selected plutons are: the Vila Pouca de Aguiar and the Lavadores-Madalena plutons with I-type affinities and the Vieira do Minho pluton, an l-S transitional type. Zircon occurs as euhedral to subhedral crystals and exhibit finely concentric oscillatory magmatic zoning mainly related to variations of Hf, Y, U and Th concentrations. Most zircon crystals show the dominant “xenotime” substitution. The zircon crystals have Zr/Hf ratio in the range of 21 to 52, with no significant differences between the different granites. These values are in the same range of other peraluminous granites and are in accordance with a crustal signature of zircon. Moreover, the range of Zr/Hf values in zircon crystals overlaps with that of crustal sources and consequently to the potential protoliths proposed in the genesis of the Vieira do Minho and the Vila Pouca de Aguiar plutons, namely meta-igneous crustal sources at different levels. Although zircon from the Lavadores-Madalena pluton has a compositional range similar to the other plutons, an origin by hibridisation has been proposed. However, similar zircon chemistry between this pluton and Vila Pouca de Aguiar and Vieira do Minho plutons could also suggest a similar crustal source.<br><br>Se han seleccionado tres plutones graniticos variscos en el norte de Portugal para el estudio de la composición del circón. Los plutones son: Vila Pouca de Aguiar y Lavadores-Madalena con afinidad de tipo-I y el plutón de Vieira do Minho de tipo transicional I-S. Los circones se presentan en cristales euhédricos a subhédricos y tienen zonados magmáticos, concéntricos oscilatorios finos ligados principalmente a variaciones de las concentraciones del Hf, Y, U y Th. La mayoría de los cristales de circón muestran la sustitución dominante “xenotima”. Los zircones tienen relaciones Zr/Hf que varían en el rango 21–52, sin diferencias significativas entre los diferentes granitos. Estos valores son idénticos a otros granitos peralumínicos y son consistentes con circones de origen cortical. Además, las relaciones Zr/Hf coinciden con las de protolitos corticais y, en consecuencia con los propuestos en la génesis de los plutones de Vila Pouca de Aguiar y Vieira de Minho, en particular rocas metaigneas. Aunque los circones del plutón Lavadores-Madalena tienen una composicíon similar a los otros plutones, fue propuesto un origen por hibridacíon. Sin embargo la similitud química de los circones de este plutón con los otros puede tambíen sugerir un origen similar

Avaliação das propriedades mecânicas da madeira in situ por ensaios em mesoprovetes

Uma das principais dificuldades da avaliação do estado de segurança de estruturas de madeira existentes é a determinação das propriedades mecânicas a utilizar para efeitos de cálculo. Os procedimentos habituais de estabelecimento das propriedades mecânicas com base no estabelecimento de classes de resistência por avaliação visual validada com ensaios não-destrutivos conduzem a resultados muito conservativos. No presente trabalho será apresentado um método semi-destrutivo que avalia a resistência à tracção da madeira através de amostras recolhidas do elemento estrutural, sendo estabelecidas relações entre resultados análogos de mesoprovetes e provetes normalizados para peças de pinho bravo (Pinus pinaster Ait.) e castanho nacional (Castanea sativa Mill.)

A semi-destructive tension method for evaluating the strength and stiffness of clear wood zones of structural timber elements in-service

The paper presents a new semi destructive method for obtaining a prediction of the tension parallel to the grain properties of clear wood of structural timber members. This method is less intrusive than other existing methods and consists in extracting four small specimens along the length of the timber members. The tension strength and stiffness obtained is intended to be used as input data for the assessment of timber members in situ. Since the method only provides information regarding clear wood, it will have to be used together with other non or semidestructive methods that could accommodate the effect of defects on the loss of clear wood properties. The validation of the method was carried out by a comparison with results obtained from a standard method used for determination of clear wood properties. The results show a good agreement between stiffness values but a medium agreement in the case of tension strength.The authors acknowledge the support given by the Fundacao para a Ciencia e a Tecnologia (FCT) for the PhD Grant SFRH/BD/27353/2006, as well as for the research Project "Safety evaluation of timber structures by means of non-destructive tests and stochastic analysis" (FCT PTDC/ECM/66527/2006)

Selected research and case studies in ancient portuguese structures

The present paper presents some of the recent activity of University of Minho, regarding case studies for Portuguese timber structures in four ancient buildings, including the Cathedral of Porto, a Church in Coimbra and a Church in Braga. NDT is combined with analysis methods aiming at non-invasive strengthening solutions or replacement of the timber structure (only as a last resort). Research studies carried out in UM and currently running on LNEC and UM are also presented, being showed the relevance of this research studies for the assessment and analysis of historical timber structures

Avaliação de insumos agrícolas por meio de testes ecotoxicológicos: fase preliminar.

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Attachment orientations and family functioning: The mediating role of emotion regulation.

Attachment insecurity has been found to be associated with poor family functioning. The mechanisms underlying this link, however, are less explored. This study examines the potential mediating role of emotion regulation in the association between attachment orientations and family functioning. Self-report scales measuring attachment, family functioning, and emotion regulation were administered to 132 adults (58% women; 57.63 years). Results showed that both attachment anxiety and attachment avoidance were associated with poor family functioning. Furthermore, emotion suppression, but not positive reappraisal, was found to partially mediate the association between attachment insecurity (both anxiety and avoidance) and perceived family functioning. Findings suggest that emotion regulation seems to play a role in the impact that attachment orientations may have on family functioning.Fundação para a Ciência e Tecnologia - FCTinfo:eu-repo/semantics/publishedVersio