Mechanical and electrical characterization

Carbon fiber laminates and sandwich structures are widely used due to their extraordinary mechanical performance (high specific strength, specific modulus, resistance to corrosion and resistance to fatigue), in the case of sandwiches, the high performance of the carbon laminates can be increased by the low density of the core. Besides that, carbon fiber is a conductive material, beyond its mechanical advantages, it has the potential to be used as a self-sensing material. This work aimed to analyze the use of sandwich composite structures in aircraft, to manufacture, and to study the mechanical and electrical properties of a sandwich composed of two carbon fiber faces and a structural foam core. The experimental work started with a study on the foam core, to access the impact of the adhesive curing temperature in the foam’s mechanical behavior. There was an increase on the ductility of the foam, but the flexural strength did not suffer significant changes. Posteriorly, three-point bending tests were carried out on carbon fiber laminates, with two different geometries, so compressive and tensile failures could be studied. The specimens that failed to compression showed a flexural strength of 1066.21±4.7% MPa, while the ones that failed under a flexural stress of 1238.49±7% MPa. The sandwich specimens with different adhesive bonds and geometries were tested and the short samples with reinforced bond failed to compression under a flexural stress of 100 MPa ± 5%, while the long samples showed several failure modes under a flexural stress of 86 MPa ± 7%. An electromechanical analysis was conducted to study the piezoresistive response of the sandwich skins. From this analysis was possible to show that there is indeed a relation between the electrical resistance and the applied strain.Os laminados de fibra de carbono e as estruturas em sanduíche são amplamente utilizadas devido ao seu elevado desempenho mecânico (elevada resistência específica, módulo específico, resistência à corrosão e resistência à fadiga), que no caso das sanduíches, é acrescido da baixa densidade do núcleo. Além disso, a fibra de carbono é um material condutor, portanto para além das vantagens mecânicas, este material tem o potencial de ser utilizado como um material capaz de detetar dano e deformação sem que a necessidade de sensores. Neste trabalho pretendeu-se analisar o uso de estruturas compósitas em sanduíches em aeronaves, fabricar e estudar as propriedades mecânicas e elétricas de uma sanduíche composta por duas faces de fibra de carbono e um núcleo de espuma estrutural. Na primeira fase do trabalho experimental, foi feito um estudo sobre o núcleo de espuma, com o objetivo de averiguar qual o impacto da temperatura de cura do adesivo. Houve um aumento da ductilidade do material, mas sem impactos significativos ao nível da tensão de cedência. Posteriormente, foram testados à flexão laminados de fibra de carbono, com duas geometrias de forma a serem obtidos modos de falha à compressão e à tração. Verificou-se que os laminados apresentaram um modo de dano nas fibras à compressão, para uma tensão na ordem dos 1066 MPa ± 5%, enquanto que os laminados cuja ruína ocorreu na face à tração a uma tensão na ordem dos 1238 MPa ± 7%. As amostras de sanduíches com diferentes composições adesivas e geometrias foram testadas e as de menor dimensão com reforço adesivo cederam à compressão com uma tensão máxima na ordem de 100 MPa ± 5%, enquanto que as de maior dimensão apresentaram diversos modos de falha a uma tensão na ordem dos 86 MPa ± 7%. Recorrendo a uma análise eletromecânica, foi estudada a resposta piezoresistiva dos laminados constituintes das faces das sanduíches. Desta análise foi possível demonstrar que existe efetivamente uma relação entre a resistência elétrica e a deformação do material

The role of human paraoxonase 1 (PON-1) in viral infections

Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas MonizAccording to the World Health Organization, Human Immunodeficiency Virus, Hepatitis B virus and Hepatitis C virus are one of the most common causes of chronic viral related disease. The Paraoxonase-1enzyme is a calcium-dependent enzyme associated to high density lipoprotein, with various activities, including paraxaonase, arylesterase and lactonase. This ability to hydrolase various subtracts seems to give the enzyme antioxidant properties and sensibility to oxidative stress. This review cross references the information of most of the recent and available studies done in the area and tries to demonstrate the connections and the importance of the Paraoxonase-1 enzyme that could provide invaluable clinical information. Several studies conclude that significant alterations occur on the enzymatic activity of Paraoxonase-1 in Human Immunodeficiency Virus, Hepatitis B virus and Hepatitis C virus infected patients. This modifications seem to occur due to the increased levels caused by the infections on the organism, leading to multiple disruption on antioxidant and anti-inflammatory pathways that were demonstrated to involve Paraoxonase-1. Although Paraoxonase-1 activity alterations seem to be caused by malignant causes, positive and useful clinical information might be extracted by measuring such alterations. Paraoxonase-1 possibly will be used with more research in future as a biomarker for some viral infections.De acordo com a Organização Mundial da Saúde, o Vírus da Imunodeficiência Humana, o vírus da Hepatite B e o vírus da Hepatite C são uma das causas mais comuns de doença crónica com origem viral em todo o mundo. A enzima Paraoxonase-1 é uma enzima dependente do cálcio associada às lipoproteínas de alta densidade, com várias atividades, incluindo paraxaonase, arilesterase e lactonase. A capacidade de hidrolisar vários substratos parece dar à enzima propriedades antioxidantes e sensibilidade ao estresse oxidativo. Este trabalho faz uma revisão dos estudos mais recentes e relevantes na área e tenta demonstrar as interligações e importância da enzima Paraoxonase-1, que pode fornecer informações clínicas significativas. Vários estudos apontam para alterações significativas que ocorrem na atividade enzimática da Paraxonase-1 em pacientes infetados com vírus da Imunodeficiência Humana, vírus da Hepatite B e vírus da Hepatite C. Estas modificações parecem ocorrer devido as alterações das atividades da enzima causados pelas infeções no organismo, conduzindo a várias perturbações nas vias anti-oxidantes e anti-inflamatórias, que parecem envolver a Paraoxonase-1. Sendo as alterações na atividade da Paraoxonase-1 aparentemente motivadas por causas malignas, podem ser retiradas informações clínicas úteis através da avaliação de tais alterações. A enzima Paraoxonase-1 possivelmente poderá ser usada, com mais pesquisas no futuro, como biomarcador para as infeções virais

Landscape Ecology dialogue: facing societal and environmental challenges in Southern Europe

A Universidade de Évora aprovou, em 2013, o Mestrado em Ecologia da Paisagem, o 1º em Portugal, cuja 1ª edição vai ter lugar no próximo ao letivo. A presente conferência tem como objetivo dar a conhecer e divulgar o referido mestrado aos potenciais interessados, trazendo para o diálogo os desafios que atualmente se colocam em Ecologia da Paisagem, nomeadamente os sociais e ambientais, num contexto transdisciplinar que lhe é inerente. Serão abordados temas dentro de um vasto leque de realidades, questões e escalas de análise, desde o ensino à investigação e à sua aplicação prática, para o que se convidaram especialistas e investigadores de diferentes países, com diferentes competências e formações. Pretende-se identificar as questões mais atuais e os desafios a considerar no futuro, articulando ensino e investigação e equacionado de que forma a Ecologia da Paisagem contribui para dar resposta às rápidas transformações e dinâmicas territoriais e ambientais. As apresentações da conferência podem ser solicitadas à organização por correio electrónico

Tumores gliais epileptogénicos

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2016Os tumores gliais epileptogénicos são neoplasias intrínsecas do parênquima cerebral que causam epilepsia. A maior parte são gliomas de baixo grau, sendo os gangliogliomas e os tumores neuroepiteliais disembrioplásticos (DNT) os que mais frequentemente cursam com epilepsia. A importância deste tema prende-se com o facto de que tanto a epilepsia, pelas crises epiléticas, como os fármacos antiepiléticos pelos efeitos acessórios que podem provocar, serem causas importantes de co-morbilidades e de uma pior qualidade de vida. No caso dos tumores gliais epileptogénicos, a epilepsia é muitas vezes refratária, por isso a solução para o seu tratamento pode passar pela excisão cirúrgica, a qual, frequentemente, é curativa. Neste trabalho, é feita uma revisão sobre os diversos aspetos clínicos, neuropatológicos, e etiopatogénicos dos tumores gliais epileptogénicos, e são apresentados dois casos ilustrativos desta patologia, o primeiro respeitante a um doente com um glioma angiocêntrico, o segundo correspondente a um outro com um DNT, ambos tratados no âmbito do programa do Grupo da Cirurgia de Epilepsia do Hospital de Santa Maria (CHLN).Epilepsy associated tumours are cerebral tumours that cause seizures. The majority are low-grade gliomas, such as gangliogliomas and dysembrioplastic neuroepitelial tumours, which are the most epileptogenic. The importance of this issue lies in the fact that both epilepsy and antiepileptic drugs are major causes of co-morbidities and a worse quality of life. In this type of tumours, epilepsy is often refractory to medical treatment, so surgery is usually done, with excellent seizure-free outcomes. This paper reviews epileptogenic clinical, neuropathological and etiopathogenic aspects of glial epileptogenic tumours, and there are two patients studied with epileptogenic glial tumours, one with angiocentric glioma and another with DNT, both followed-up at Hospital de Santa Maria

Estudo laboratorial de solos tratados com cal : modelos de comportamento

Este documento não tem folha de rostoTese de mestrado. Mecânica dos Solos e Engenharia Geotécnica. Faculdade de Engenharia. Universidade do Porto. 200

Serological and Molecular Survey of Leishmania infantum in a Population of Iberian Lynxes (Lynx pardinus)

This article belongs to the Special Issue Advances in Leishmania Research: From Basic Parasite Biology to Disease Control.Leishmania infantum, the sand fly-transmitted protozoan parasite responsible for leishmaniasis in humans, dogs, and cats, is endemic in the Iberian Peninsula. However, the impact of L. infantum infection on the conservation of the endangered Iberian lynx (Lynx pardinus) is unknown. Herein, we describe for the first time the occurrence of L. infantum infection among a population of reintroduced and wild-born L. pardinus living in the Portuguese Guadiana Valley Park. The presence of infection was addressed by molecular detection of Leishmania kinetoplast DNA (kDNA) in 35 lynxes, with further confirmation of L. infantum species performed by an internally transcribed spacer (ITS)-1 sequencing. Eight blood samples were positive for kDNA, and ITS-1 sequencing confirmed the presence of L. infantum in two of those samples. Exposure to Leishmania was screened in a group of 36 lynxes using an immunofluorescence antibody test (IFAT) and a multi-antigen enzyme-linked immunosorbent assay (ELISA), using SPLA, rK39, and CPX as Leishmania-specific antigens. Four animals presented a positive IFAT at a dilution of 1:40. Eight samples were considered seropositive to all ELISA Leishmania-specific antigens. Agreement between PCR, IFAT, and all ELISA antigens was found for 1 in 27 samples. These results highlight the susceptibility of autochthonous L. pardinus to L. infantum infection. Further investigation is required to assess the impact of L. infantum infection on this wild species conservation.This research was funded by the Parasite Disease Group at i3S, Porto, Portugal, and the Portuguese Foundation for Science and Technology (FCT) under the PhD scholarship number 2020.07306.BD and the project PTDC/CVT-CVT/6798/2020.info:eu-repo/semantics/publishedVersio

In vivo biodistribution of carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles in rats

Carboxymethylchitosan/poly(amidoamine) dendrimer nanoparticles (CMCht/PAMAM) have recently been proposed for intracellular drug delivery purposes. These are constituted by a PAMAM dendrimer core grafted with chains of CMCht. Previous reports have shown that these nanoparticles disclosed an improved cytotoxic profile when compared to traditional dendrimers. Following on these results the present study aims to assess, for the first time, the short-term in vivo biodistribution of CMCht/PAMAM dendrimer nanoparticles upon intravenous injections in Wistar Han rats. The rats were injected in the tail vein with 1 and 10 µg/g, respectively, of fluorescein isothiocyanate (FITC) labeled CMCht/PAMAM dendrimer nanoparticles. Brain, liver, kidney and lung were collected at 24, 48 and 72 hours after injection and further stained with phalloidin-TRITC (red) and DAPI (blue) to trace the nanoparticles within the tissues. Liver, kidney and lung were also stained for haematoxylin and eosin in order to assess possible alterations in the morphology of these organs. CMCht/PAMAM dendrimer nanoparticles were observed within the vascular space and parenchyma of liver, kidney and lung, and in the choroid plexus, after 24, 48 and 72 hours upon intravenous injection of nanoparticles. No particles were observed in the brain parenchyma, nor any apparent deleterious histological changes, were observed within these organs. The present report revealed that CMCht/PAMAM dendrimer nanoparticles were stable in circulation for periods up to 72 hours, targeting the main organs/systems through internalization by the cells present in their parenchyma. These results provide positive indicators to their potential use in the future as intracellular drug delivery systems.Funds attributed by Fundação Calouste de Gulbenkian to A.J. Salgado under the scope of the The Gulbenkian Programme to Support Research in Life Sciences; Portuguese Foundation for Science and Technology (Science 2007 Program – A.J. Salgado, pre- and postdoctoral fellowships to J.M. Oliveira – SFRH/BPD/63175/2009, A.M. Frias – SFRH/BPD/45206/2008, F. Marques – SFRH/BPD/33379/2008, A.M. Falcão – SFRH/BD/44485/2008, S. Roque – SFRH/BD/24539/2005; S.R. Cerqueira – SFRH/BD/SFRH/BD/48406: 2008)

Selective impact of Tau loss on nociceptive primary afferents and pain sensation

Tau protein hyperphosphorylation and consequent malfunction are hallmarks of Alzheimer's disease pathology; importantly, pain perception is diminished in these patients. In physiological conditions, Tau contributes to cytoskeletal dynamics and in this way, influences a number of cellular mechanisms including axonal trafficking, myelination and synaptic plasticity, processes that are also implicated in pain perception. However, there is no in vivo evidence clarifying the role of Tau in nociception. Thus, we tested Tau-null (Tau-/-) and Tau+/+ mice for acute thermal pain (Hargreaves' test), acute and tonic inflammatory pain (formalin test) and mechanical allodynia (Von Frey test). We report that Tau-/- animals presented a decreased response to acute noxious stimuli when compared to Tau+/+ while their pain-related behavior is augmented under tonic painful stimuli. This increased reactivity to tonic pain was accompanied by enhanced formalin-evoked c-fos staining of second order nociceptive neurons at Tau-null dorsal horn. In addition, we analyzed the primary afferents conveying nociceptive signals, estimating sciatic nerve fiber density, myelination and nerve conduction. Ultrastructural analysis revealed a decreased C-fiber density in the sciatic nerve of Tau-null mice and a hypomyelination of myelinated fibers (Ad-fibers) - also confirmed by western blot analysis - followed by altered conduction properties of Tau-null sciatic nerves. To our knowledge, this is the first in vivo study that demonstrates that Tau depletion negatively affects the main systems conveying nociceptive information to the CNS, adding to our knowledge about Tau function(s) that might also be relevant for understanding peripheral neurological deficits in different Tauopathies.We would like to thank Drs Joao Relvas, Joana Paes de Faria Monteiro and Nuno Dias for their comments in this work. Many thanks to Dr Joao Relvas for the MBP antibody. The work was supported by grants "SFRH/BPD/80118/2011", "PTDC/SAU-NMC/113934/2009" funded by FCT - Portuguese Foundation for Science and Technology and project DoIT - Desenvolvimento e Operacionalizacao da Investigacao de Translacao (No. do projeto 13853), funded by Fund Europeu de Desenvolvimento Regional (FEDER) through the Programa Operacional Fatores de Competitividade (POFC). Author's contributions: experimental design - IS, HA, VP, AA, and NS; performed research - IS, HA, VP, AL, SL, SS, SP, AC, FPR, and RF; data analyses - IS, HA, AL, VP, SC, and FPR; and manuscript preparation - IS, HA, VP, and NS

Conhecimento, Responsabilidade, Visão e Futuro: bases programáticas da Lista F para o 3.º mandato do Conselho Geral da Universidade de Évora 2016-20

O presente documento inclui o programa de acção e os elementos de campanha da Lista F, candidata ao 3.º mandato do Conselho Geral da Universidade de Évora (2016-20)