Recursos de colección

UTL Repository Universidade Técnica de Lisboa (32.124 recursos)

O Repositório Institucional da Universidade Técnica de Lisboa desenvolvido no âmbito do projecto RCAAP. Este repositório destina-se a recolher, preservar e disponibilizar o acesso às publicações científicas e didácticas de seis: Escolas da UTL: Faculdade de Medicina Veterinária, Instituto Superior de Agronomia, Instituto Superior de Economia e Gestão, Instituto Superior de Ciências Sociais e Políticas , Faculdade de Motricidade Humana, Faculdade de Arquitectura. O Instituto Superior Técnico, igualmente Escola Da UTL, tem repositório independente.

DEF - Artigos de Revistas

Mostrando recursos 1 - 20 de 47

  1. Storage stability of Jatropha curcas L. oil naturally rich in gamma-tocopherol

    Rodrigues, Joana; Miranda, Isabel; Furquim, Leonnardo; Gominho, Jorge; Vasconcelos, Manuel; Barradas, Gonçalo; Pereira, Helena; Bianchi-de-Aguiar, Fernando; Ferreira-Dias, Suzana
    tJatropha curcas L. is an interesting tropical oil crop for biodiesel production. However, seed conservationuntil oil extraction may be a problem under high temperature and humidity. In this study, Jatropha curcasL. seeds grown in Mozambique and presenting 160 mg/kg of gamma-tocopherol in their oil were storedfor 42 days, in dark, at 35◦C and 75% or 92% relative humidity (RH). Along storage, the oil was extractedand analysed in terms of fatty acid composition, tocopherol content, acidity, initial and final oxidationproducts (monitored by K232 and K270 values, respectively).Jatropha seeds presented an initial water content of 8.4% and an oil content of 45.7%...

  2. Effects of an extremely dry winter on net ecosystem carbon exchange and tree phenology at cork oak woodland

    Costa-e-Silva, Filipe; Correia, Alexandra C.; Piayda, Arndt; Dubbert, Maren; Rebmann, Corinna; Cuntz, Matthias; Werner, Christiane; David, Jorge Soares; Pereira, João Santos
    In seasonally dry climates, such as the Mediterranean, lack of rainfall in the usually wet winter may originate severe droughts which are a main cause of inter-annual variation in carbon sequestration. Leaf phenology variability may alter the seasonal pattern of photosynthetic uptake, which in turn is determined by leaf gas exchange limitations. The current study is based on the monitoring of an extremely dry winter in an evergreen cork oak woodland under the Mediterranean climate of central Portugal. Results are focused on net ecosystem CO2 exchange (NEE), phenology and tree growth measurements during two contrasting years: 2011, a wet year with a typical summer drought pattern...

  3. Classification modeling based on surface porosity for the grading of natural cork stoppers for quality wines

    Oliveira, Vanda; Knapic, Sofia; Pereira, Helena
    tThe natural cork stoppers are commercially graded into quality classes according with the homogeneity of theexternal surface. The underlying criteria for this classification are subjective without quantified criteria and standardsdefined by cork industry or consumers. Image analysis was applied to premium, good and standard quality classes tocharacterize the surface of the cork stoppers and stepwise discriminant analysis (SDA) was used to build predictiveclassification models. The final goal is to analyze the contribution of each porosity feature and propose an algorithmfor cork stoppers quality class classification. This study provides the knowledge based on a large sampling to anaccurate grading of natural...

  4. Chemical composition and kraft pulping potential of 12 eucalypt species

    Neiva, Duarte; Fernandes, Luís; Araújo, Solange; Lourenço, Ana; Gominho, Jorge; Simões, Rogério; Pereira, Helena
    Eucalypts are among the most important short-rotation hardwoods, planted worldwide for the pulp and paper industry. Even though the genus comprises over 700 species, only about a dozen species are used for pulping purposes, therefore, showing the potential for diversification. Six-year-old eucalypt trees from 12 species (Eucalyptus botryoides, Eucalyptus camaldulensis, Eucalyptus globulus, Eucalyptus grandis, Corymbia maculata, Eucalyptus ovata, Eucalyptus propinqua, Eucalyptus resinifera, Eucalyptus rudis, Eucalyptus saligna, Eucalyptus sideroxylon, and Eucalyptus viminalis) were analyzed for chemical composition, fiber morphological, pulping and handsheet paper properties to determine their kraft pulping suitability. The 12 species showed substantial differences regarding extractives (6.1–18.9%), lignin (21.6–30.8%) and holocellulose content (55.4–70.1%). The high inter-species variation...

  5. Sensory impact of alternative ageing technology for the production of wine brandies

    Caldeira, Ilda; Anjos, Ofélia; Belchior, A. Pedro; Canas, Sara
    The production of wine brandies requires their stage in wooden barrels, for a minimum period of time, a process called ageing or maturation. Due to the high cost of this process, alternative technologies are being studied in order to accelerate the ageing process, such as the use of wood fragments inside of stainless steel tanks. The present work evaluates the influence of different ageing technologies on the sensory profile of the brandy. A brandy was aged, during two years, in 650 L wooden barrels and in 3000 L stainless steel tanks. Both had Limousin oak (Quercus robur) and Portuguese chestnut staves (Castanea sativa). The...

  6. Physical, chemical and mechanical properties of Pinus sylvestris wood at five sites in Portugal

    Fernandes, Cláudia; Gaspar, Maria João; Pires, Jani; Alves, Ana; Simões, Rita; Rodrigues, José Carlos; Silva, Maria Emília; Carvalho, Ana; Brito, José Eduardo; Lousada, José Luís
    Research Article

  7. CliPick - Climate change web picker. A tool bridging daily climate needs in process based modelling in forestry and agriculture

    Palma, J.H.N.
    Resource Communication

  8. Using the SUBER model for assessing the impact of cork debarking rotation on equivalent annual annuity in Portuguese stands

    Paulo, Joana A.; Tomé, Margarida
    Research Article

  9. Chemical characterization and extractives composition of heartwood and sapwood from Quercus faginea

    Miranda, Isabel; Sousa, Vicelina; Ferreira, Joana; Pereira, Helena
    Research Article

  10. Species-specific adaptations explain resilience of herbaceous understorey to increased precipitation variability in a Mediterranean oak woodland

    Jongen, Marjan; Hellmann, Christine; Unger, Stephan
    To date, the implications of the predicted greater intra-annual variability and extremes in precipitation on ecosystem functioning have received little attention. This study presents results on leaf-level physiological responses of five species covering the functional groups grasses, forbs, and legumes in the understorey of a Mediterranean oak woodland, with increasing precipitation variability, without altering total annual precipitation inputs. Although extending the dry period between precipitation events from 3 to 6 weeks led to increased soil moisture deficit, overall treatment effects on photosynthetic performance were not observed in the studied species. This resilience to prolonged water stress was explained by different physiological and morphological strategies to withstand periods below the wilting...

  11. Ecological implications of fine-scale fire patchiness and severity in tropical savannas of northern Australia

    Oliveira, Sofia L.J.; Campagnolo, Manuel L.; Price, Owen F.; Edwards, Andrew C.; Russel-Smith, Jeremy; Pereira, J.M.C.
    Research Article

  12. Addressing wildfire risk in a landscape-level scheduling model: an application in Portugal

    Ferreira, Liliana; Constantino, Miguel F.; Borges, José G.; Garcia-Gonzalo, Jordi
    Fundamental Research - Forest Management

  13. Predicting site index from climate and soil variables for cork oak (Quercus suber L.) stands in Portugal

    Paulo, Joana Amaral; Palma, J.H.N.; Gomes, Alberto Azevedo; Faias, Sónia Pacheco; Tomé, José; Tomé, Margarida
    Site productivity, assessed through site index, was modelled using partial least squares regression as a function of soil and climatic variables. Two alternative models were developed: a full model, considering all available explanatory variables, and a reduced model, considering only variables that can be obtained without digging a soil pit. The reduced model was used for mapping the site index distribution in Portugal, on the basis of existing digital cartography available for the whole country. The developed models indicate the importance of water availability and soil water holding capacity for site index value distribution. Site index was related to climate, namely evaporation and frost, and soil characteristics such...

  14. Moderate biomanipulation for eutrophication control in reservoirs using fish captured in angling competitions

    Amaral, S.D.; Franco, A.; Ferreira, M.T.
    Angling competitions are a popular leisure activity in reservoirs of Southern Portugal. These competitions can gather more than 100 anglers aiming to catch the maximum fish weight. Groundbaiting and catch-andrelease angling are two common practices for anglers in competition. In this study, the loads of nutrients from commercial groundbait powders used in angling competitions in the Maranhão reservoir and the possible balance out of those nutrients through a moderate biomanipulation of the fish biomass caught in competitions were analysed. In order to achieve this aim, chemical analyses to groundbait powders most purchased by Portuguese anglers and to fish species most captured in competitions were made. Mass balances on inputs and...

  15. Biomass conversion and expansion factors are afected by thinning

    Enes, Teresa Duque; Fonseca, Teresa Fidalgo
    Aim of the study: The objective of this paper is to investigate the use of Biomass Conversion and Expansion Factors (BCEFs) in maritime pine (Pinus pinaster Ait.) stands subjected to thinning. Area of the study: The study area refers to different ecosystems of maritime pine stands in Northern Portugal. Material and methods: The study is supported by time data series and cross sectional data collected in permanent plots established in the North of Portugal. An assessment of BCEF values for the aboveground compartments and for total was completed for each studied stand. Identification of key variables affecting the value of the BCEFs in time and with...

  16. Developing post-fire Eucalyptus globulus stand damage and tree mortality models for enhanced forest planning in Portugal

    Marques, Susete; Garcia-Gonzalo, Jordi; Borges, José G.; Botequim, Brigite; Oliveira, M. Manuela; Tomé, José; Tomé, Margarida
    Research Article

  17. Analysis of the performance of different implementations of a heuristic method to optimize forest harvest scheduling

    Bachmatiuk, Joanna; Garcia-Gonzalo, Jordi; Borges, José G.
    Research Article

  18. Heartwood, sapwood and bark variation in coppiced Eucalyptus globulus trees in 2nd rotation and comparison with the single stem 1st rotation

    Miranda, Isabel; Gominho, Jorge; Pereira, Helena
    Research Article

  19. Religious affiliation modulates weekly cycles of cropland burning in Sub-Saharan Africa

    Pereira, J.M.C.; Oom, Duarte; Pereira, Paula; Turkman, Antónia A.; Turkman, K. Feridun
    Research Article

  20. Genetic diversity and host alternation of the egg parasitoid Oencyrtus pityocampae between the pine processionary moth and caper bug

    Samra, Shahar; Ghanim, Murad; Protasov, Alex; Branco, Manuela; Mendel, Zvi
    Research Article

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