2,005 research outputs found

    Freeze tolerance of the yeast Torulaspora delbrueckii : cellular and biochemical basis

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    The freeze-stress responses to prolonged storage at - 20 °C in Torulaspora delbrueckii PYCC5323 were investigated. In this yeast no loss of cell viability was observed for at least 120 days during freezing at - 20ºC, whereas a loss of 80% was observed in a commercial baker's yeast after 15 days. In the former strain, freeze resistance was dependent on an adaptation process. The primary cell target of freeze stress was the plasma membrane, preservation of it’s integrity being related with a lower increase of lipid peroxidation and with higher resistance to H2O2, but not with intracellular trehalose concentration.Fundação para a Ciência e a Tecnologia (FCT) - grant (PRAXIS XXI/BD/21543/99)

    Integrating social concerns into electricity planning

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    This paper deals with the complexity of the social issues surrounding electricity planning. A methodology is presented establishing a possible way of allocating weights to the most important social impacts of the electricity generation options and extending these results to the evaluation of future electricity plans. The process combined Delphi method with the Analytic Hierarchy Process, for the pairwise comparison of the electricity generation technologies against the social criteria. A social impact score was then derived and assigned to each technology. In order to obtain a final ranking of future feasible plans, these overall social scores of the electricity generation alternatives were aggregated using an additive function. The final output of the social analysis is an Average Social Index of each possible electricity generation mix

    Evaluation of MAP engineering design parameters on quality of fresh-sliced mushrooms

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    Modified atmosphere packaging (previous termMAPnext term) relies on the interplay between product-respiration and package-film-permeability with the aim of maintaining initial quality and extending shelf-life of fresh produce. This work evaluates the effect of previous termMAPnext term engineering design parameters (amount of product, number of perforations and weight of CO2 scavenger) on quality of sliced mushrooms. Sliced button mushrooms were packed in a tray, covered with cellophane film, and stored at 10 °C for 3 days. Headspace gas composition and chemical and physical quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. All design parameters produced a significant effect (p < 0.05) on quality. Addition of CO2 scavenger in the package increased the deterioration of mushrooms. previous termMAP optimisation design requires consideration of mushroom weight and number of film perforations. The optimal conditions found were 110 g of sliced mushrooms and 2 perforations (0.33 mm diameter) which led to an equilibrium gas composition of 3.6% O2 and 11.5% CO2, after 3 days of storage at 10 °C.The first author acknowledge financial support from the Erasmus Program (2009) and research funding was provided under the NDP, through FIRM (08/R&D-UL/661), administered by the Department of Agriculture, Fisheries and Food, Ireland. Authors would also like to acknowledge Innovia Films Ltd. (UK) for supplying the packaging materials

    The impacts of wind power on power systems operation

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    The wind power sector is growing rapidly in Portugal and the National objectives for energy include a significant increase of wind power during the next years. The large penetration of wind power in Portugal will influence significantly the energy system cost, but it seems also essential to materialize the international energetic and environmental commitments. This paper focuses on the impact of large scale wind scenarios on the power system operation. CO2 abatement potential is estimated along with the effects on the operating costs of thermal power plants. Simulations for different wind scenarios were run for 2016, assuming the possibility of exports. According to the results, it seems that about 20% of wind power penetration may be achieved in Portugal with minor losses of efficiency of the global system

    Development of shelf-life kinetic model for modified atmosphere packaging of fresh sliced mushrooms

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    Mushrooms are highly perishable and their shelf-life depends on processing, package properties and environmental conditions during storage and distribution. The aims of this work were to evaluate the effect of temperature and number of film perforations on quality and develop shelf-life kinetic model for a modified atmosphere packaging (MAP) for sliced button mushrooms. Sliced mushrooms were packed in a tray, covered with cellophane film, and stored for 7 days at four levels of temperature (0,5, 10, and 15 C) and three levels of perforations at each temperature ranging the number of perforations from 1 (58 perforations per m2) to 6 (349 perforations per m2). Headspace gas composition and quality parameters (weight loss, pH, firmness and colour) were measured throughout the storage period. Increasing the storage temperature required an increase of the number of perforations in order to obtain the optimum MAP conditions. Temperature had a significant effect (p < 0.05) on quality of sliced mushrooms. Firmness was identified as a critical quality parameter; therefore, a kinetic model was developed to describe the influence of temperature on firmness and predict shelf-life of sliced mushrooms. Fresh sliced mushrooms had a shelf-life of 1, 2, 4, and 7.5 days at 15, 10, 5, and 0 C, respectively, under optimum MAP conditions.The first author acknowledge financial support from the Erasmus Programme (2009) and research funding was provided under the NDP, through FIRM (08/R&D-UL/661), administered by the Department of Agriculture, Fisheries & Food, Ireland. Authors would also like to acknowledge Innovia Films Ltd. (UK) for supplying the packaging materials

    An overview of the Portuguese wind power sector

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    In the following paper the present situation of the electricity production from Renewable energy Sources (RES) in Portugal is analysed, giving particular attention to the wind power sector due to its increasing importance. The evolution of the electricity system is presented along with the strategies for the sector, and future prospects for the RES. Although the high interest of private companies in the wind sector the administrative and grid barriers represent major obstacles to the wind power development. The problem of the wind intermittency and uncertainty is also discussed. The improvement of interconnection capacity and the increase of power reserve are identified as key requirements for ensuring the security of supply. A clear comprehension of all these aspects is fundamental to aim for an integrated multidimensional wind power planning.(undefined

    Electricity power planning: the role of wind energy

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    Combining energy efficiency with renewable energy sources constitutes a key strategy for a sustainable future. The wind power sector stands out as a fundamental element for the achievement of the European renewable objectives and Portugal is no exception to the increase of the wind energy for the electricity generation. This work proposes an optimization model for the long range electricity power planning in a system similar to the Portuguese one, where the expected impacts of the increasing installed wind power on the operating performance of thermal power plants are taken into account. The main results indicate that the increasing penetration of wind power in the electricity system will have significant effects on the combined cycle gas power plants operation and on the theoretically expected cost reduction and environmental gains. This research demonstrated the need to address the impact that energy sources with variable output may have, not only on the short-term operational planning, but especially on the medium to long range planning activities, in order to meet the strategic objectives for the energy sector.Fundação para a Ciência e Tecnologia (FCT)COMPETE – Programa Operacional Factores de Competitividade under Research Project PTDC/SEN-ENR/099578/200

    Estudo das evidências de produção metalúrgica no Outeiro Redondo (Sesimbra)

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    O Outeiro Redondo (Sesimbra) é um sítio arqueológico importante da Estremadura Portuguesa, predominantemente ocupado durante o Calcolítico Pleno/Final (segunda metade do III Milénio a.C.). Este estudo foca‑se na caracterização elementar e microestrutural de 12 artefactos em liga de cobre e de um fragmento de cadinho provenientes deste sítio, contribuindo assim para o conhecimento da metalurgia primitiva naquela região. A metodologia aplicada consistiu em espectrometria de fluorescência de raios ‑X dispersiva de energias, microscopia óptica, microscopia electrónica de varrimento com microanálise de raios ‑X e microdureza Vickers. O arsénio está presente em todos os fragmentos metálicos, quer como impureza (2 wt%), os quais apresentam constituintes microestruturais característicos de diversos processos termomecânicos. O cadinho mostra evidências de uso em operações metalúrgicas de redução de minérios.The pre‑historic settlement of Outeiro Redondo located near Sesimbra is an important archaeological site of the Portuguese Estremadura region, predominantly occupied during the Full/Late Chalcolithic period (second half of the 3rd millennium B.C.). The present study focuses on the elemental and microstructural characterization of a group of 12 copper ‑based artefacts and a crucible fragment recovered from this settlement, contributing to the understanding of the Chalcolithic metallurgy in this geographic area. The applied methodology consisted of energy dispersive X ‑ray fluorescence spectrometry, optical microscopy, scanning electron microscopy with energy dispersive spectrometry and Vickers microhardness. Arsenic is present in all the metallic fragments, – whether as impurity (2 wt%) – which exhibit microstructural features characteristic of several thermomechanical processes. The crucible shows evidence of use in metallurgical operations, namely smelting.Patrocinador oficial - Fundação Millennium BCP. Apoio institucional - Biblioteca Nacional de Portugal e Parques de Sintra- Monte da Lua. O Projecto Metalurgia Primitiva no Território Português – EarlyMetal (PTDC/HIS ‑ARQ/110442/2008) financiado pela Fundação para a Ciência e Tecnologia (FCT)

    The Colors of a Bible and Three Gospels Produced in the Armenian Diaspora

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    Funding Information: This research was funded by the Portuguese Foundation for Science and Technology [Fundação para a Ciência e Tecnologia, Ministério da Educação e Ciência (FCT/MCTES)], through PhD grants awarded to Márcia Vieira [SFRH/BD/148729/2019] and to Hermine Grigoryan [PD/BD/142866/2018], CEEC junior contract awarded to Paula Nabais (2021.01344.CEECIND), UIDB/EAT/00729/2020, UIDP/00729/2020; Associate Laboratory for Green Chemistry- LAQV financed by FCT/MCTES (UID/QUI/50006/2019 and UIDB/50006/2020) and co-financed by the ERDF under the PT2020 Partnership Agreement (PO-CI-01-0145-FEDER-007265); Glass and Ceramic for the Arts—VICARTE financed by FCT/MCTES (UIDB/00729/2020 and UIDP/00729/2020); Laboratory for Instrumentation, Bio-medical Engineering and Radiation Physics—LIBPhys financed by FCT/MCTES (UIDB/04559/2020 and UIDP/04559/2020). Calouste Gulbenkian Foundation grant on Armenian Studies (No. 269685) awarded to Hermine Grigoryan. Publisher Copyright: © 2023 by the authors.The illuminated manuscripts at the Gulbenkian Museum were produced in the 17th century, in scriptoria of the Armenian diaspora. In this work, we selected analytical methods that can be used in situ to study the colors of the illuminations. Scientific analysis based on fiber-optics reflectance spectroscopy in the visible and Raman spectroscopy has shown the use of a medieval palette based on inorganic pigments such as lapis lazuli, minium, vermilion, orpiment, indigo, two different greens (vergaut and malachite), lead white and carbon black. More importantly, in this context, it showed that the very important reds and pinks are possibly based on carminic acid. The painting technique is, however, different, as are the ways of painting the faces, hands, and vestments. The range of colors in the Bible and the three Gospel Books, enhanced by lapis lazuli blue and organic reds and pinks, demonstrates a desire to create exceptional illuminated manuscripts.publishersversionpublishe
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