1,497 research outputs found

    Contributo para o estudo das plantas vasculares endémicas da Ilha das Flores (Açores).

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    IV Expedição Científica do Departamento de Biologia – Flores 1989.Conforme mostra MALATO-BELIZ (1988), o número de taxa vasculares endémicos nas ilhas dos Açores varia entre um máximo de 62 taxa (ilha de S. Miguel) e um mínimo de 11 taxa endémicos na ilha Graciosa. A pequena ilha das Flores com 51 taxa endémicos ultrapassa claramente neste particular as ilhas Graciosa (11), S. Maria (35) e Corvo (37) e quase iguala em número de espécies endémicas ilhas bastante maiores como a Terceira (55) e o Faial (55). Não admira pois que em termos da relação "nº taxa endémicos/unidade de superfície (Km2)" a ilha das Flores com 0,357 end./Km2, apenas seja ultrapassada por S. Maria (0,360 end./ Km2) e pelo Corvo (2,126 end./Km2), 0 valor médio para o arquipélago situa-se apenas nos 0,184 end./Km2. A explicação para esta relativa riqueza em espécies endémicas da ilha das Flores fica sem dúvida a dever-se à grande diversidade de biótopos que ela possui e à existência de algumas manchas vegetais menos alteradas pelo homem

    A hybrid cementitious based-G/CFRP sandwich panel: concept, design and initial outcomes

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    Nowadays, the advantages of using fibre-reinforced polymers (FRP) in Civil Engineering structures are very well-known. In comparison to other materials, the FRPs show high strength-to-weight and stiffness-to-weight ratios, as well as high corrosion resistance [1]. Moreover, they can be easily moulded into complex shapes during the manufacturing process. Due to the slenderness of the cross section components and systems [2], and their significant initial cost [3], the FRPs are typically used along with other materials in composite structural elements. In the recent years, the FRPs have been increasingly used in composite sandwich panels designed for the building and housing industry [4]. However, in terms of flooring solutions, the sandwich panels still reveal some limitations for the most typical values of spans and loads in buildings [5]. In order to overcome the aforementioned drawbacks, the EasyFloor project was launched to develop enhanced composite sandwich panels for rehabilitation of floors in buildings. One of the important innovations included in the project relies on the use of both glass and carbon fibre roving (G/CFRP). This hybrid solution aims at improving significantly both the strength and stiffness. Furthermore, the top face of the panel is made of steel fibre reinforced self-compacting micro concrete (SFRSCMC), instead of the usual FRP compressive face, aiming to overcome face wrinkling issues. Additionally, this solution can provide higher ductility, fire endurance and impact resistance [6]. Furthermore, polycianurate (PIR) closed-cell foam is used as core material of the panel. Proper adhesion between G/CFRP and SFRSCMC is developed in order to obtain the full bending capacity of the composite solution. Finally, the FRP component is produced by pultrusion, taking all the advantages of this manufacturing process. The final proposal for the hybrid sandwich panel was obtained through the use of genetic algorithms in the design, which consisted in optimizing the geometric and the mechanical properties of the panel, taking into account the following features: (i) structural and energy efficiency; (ii) durability, versatility of use, ease of handling, quick assembly and production; (iii) low maintenance needs and aesthetics. The present work describes the design solution that resulted from the optimization procedure and subsequently presents initial experimental results regarding the mechanical characterization of the different materials, as well as the FRP/SFRSCMC interface. The experimental program comprised: (i) tensile and flexural tests on both the bottom and external ribs of the C/GFRP laminate skins; (ii) tensile, compressive and direct shear tests on both foam core materials (PIR); (iii) compressive and flexural tests on the SFRSCMC top face, and; (iv) pull-off tests for the characterization of the connection between the SFRSCMC and FRP using different types of adhesives.This work is part of the research project “EasyFloor – Development of composite sandwich panels for rehabilitation of floor buildings”, involving the company ALTO – Perfis Pultrudidos, Lda., CERis/Instituto Superior Técnico and ISISE/University of Minho, supported by FEDER funds through the Operational Program for Operational Program for Competitiveness and Internationalization (POCI) and the Portuguese National Innovation Agency (ANI) - project no. 3480 (POCI-01-0247-FEDER-003480). The authors would like to thanks the following companies for suppling the adhesives: KERAKOLL, MAPEI and SIKADUR.info:eu-repo/semantics/publishedVersio

    A proactive approach to the conservation of historic and cultural Heritage: The HeritageCare methodology

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    Presently, no systematic policy for the preventive conservation of the built cultural heritage exists in South-West Europe. Current approaches for inspection, diagnosis, monitoring and reactive conservation are normally intermittent, unplanned, expensive and lack methodical strategy. The available financial resources are scarce and are mostly addressed to listed buildings. Besides, owners and stakeholders often reveal reluctance to invest in preventive conservation and maintenance programs. In view of these considerations, and driven by the principle “prevention is better than cure”, the HeritageCare project has developed a system for the preventive conservation and maintenance of the built heritage. The main aim of this paper is to briefly describe the methodology, including its three levels of service, and present the main results of the implementation and validation of the service level 1 on a case study belonging to the Portuguese architectural heritage.This work was carried out within the scope of the project HeritageCare (SOE1/P5/P0258), co-funded by the Interreg-Sudoe/FEDER program and included in the research activities of the ISISE Research Centre, also financed by FEDER funds through the Competitiveness Factors Operational Program – COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007633. Authors would like to express their gratitude to the Centre for Computer Graphics, HeritageCare partner, for the development of the platform (and supporting database) and the mobile application, outputs of the project HeritageCare. Authors would like to express their gratitude to the Santa Maria de la Real Foundation, HeritageCare partner, for the placement of the monitoring system at the Ducal Palace, Guimarães, Portugal

    Epidemiology and Clinical Forms of Primary Hyperparathyroidism: A Review

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    Primary hyperparathyroidism (PHPT) is a disease caused by overactive parathyroid glands with consequent hypercalcemia. However, its presentation is variable, with patients demonstrating a range from normocalcemia to severe hypercalcemic PHPT. The present study aims to perform a literature review on the epidemiology and the clinical forms of PHPT using information published in the PubMed and Cochrane databases. It describes data about prevalence, etiology, diagnosis, classic and non-classic manifestations, providing updated information on classical hypercalcemic hyperthyroidism, in addition to its normocalcemic variant

    Three-body correlations in Borromean halo nuclei

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    Three-body correlations in the dissociation of two-neutron halo nuclei are explored using a technique based on intensity interferometry and Dalitz plots. This provides for the combined treatment of both the n-n and core-n interactions in the exit channel. As an example, the breakup of 14Be into 12Be+n+n by Pb and C targets has been analysed and the halo n-n separation extracted. A finite delay between the emission of the neutrons in the reaction on the C target was observed and is attributed to 13Be resonances populated in sequential breakup.Comment: 5 pages, 4 figures, submitted to PR

    The potential role of polyelectrolyte complex nanoparticles based on cashew gum, tripolyphosphate and chitosan for the loading of insulin

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    Polyelectrolytic complexation has stood out due to its application in the development of drug delivery systems using biopolymers as raw materials. The formation of complexes between cashew gum and chitosan can be intermediated by cross-links, mediated by the action of the sodium tripolyphosphate crosslinking agent. These polymers have been used in the nanotechnological development of formulations to protect peptide drugs, such as insulin, allowing their oral administration. In this work, we describe the development of polyelectrolytic complexes from cashew gum and chitosan as biopolymers for oral administration of insulin. The obtained complexes showed a mean particle size of 234 nm and polydispersity index of 0.2. The complexes were 234 nm in size, PDI 0.2, zeta potential 4.5 mV and 22% trapping. The obtained complexes demonstrated considerable and promising characteristics for use as oral insulin delivery systems.e Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE), Banco do Nordeste (grant FUNDECI/2016.0015), Portuguese Science and Technology Foundation (FCT/MCT) and from European Funds (PRODER/COMPETE) through the project UIDB/04469/2020 (strategic fund), co-financed by FEDER, under the Partnership Agreement PT2020info:eu-repo/semantics/publishedVersio

    Entanglement of two-mode Gaussian states: characterization and experimental production and manipulation

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    A powerful theoretical structure has emerged in recent years on the characterization and quantification of entanglement in continuous-variable systems. After reviewing this framework, we will illustrate it with an original set-up based on a type-II OPO with adjustable mode coupling. Experimental results allow a direct verification of many theoretical predictions and provide a sharp insight into the general properties of two-mode Gaussian states and entanglement resource manipulation
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