Fracture Characterisation of bonded joints between cortical bone tissue and bone cement

The process of evolution has led to the creation of fantastic materials. Bone is one of these materials and has a complex, anisotropic, hierarchical and heterogeneous microstructure, characterised by an excellent mechanical performance. However, as it is an almost fragile material, it often ends up fracturing. These fractures decrease the patient's quality of life and entail high costs for the health system. In order to deal with these fractures, the BoFraPla project arose, which aims to develop a fibrous system for fixing bone fractures. Therefore, in the scope of the activities of this project, the present dissertation emerges, proposing to mechanically characterise the bond between the bone and bone cement. From a thorough literature review, it was found that although the bone cement has been used for more than fifty years, there are few references to its mechanical characterisation and none were found that have made a clear characterisation of the fracture process between the bone and the cement. Hence, in this report, a pure mode I characterisation (tension) through a Double Cantilever Beam (DCB) test and another pure mode II characterisation (shear) through an End-Notched Flexure (ENF) test are presented. In order to overcome the difficulties in monitoring the crack length during the laboratory tests, a method based on the equivalent crack length was used. With this method, the resistance curve was drawn for each specimen and, in most of them, the existence of thresholds was remarkable, which allowed a correct measurement of the fracture energy for each test. In order to validate the results obtained, numerical simulations were performed with cohesive models. Through the results, it was possible to determine that the chosen tests, the defined dimensions and the adopted procedure, can be used to characterise the fracture of these two materials in the studied loading modes.O processo de evolução natural levou à existência de materiais fantásticos. O osso é um destes materiais e apresenta uma microestrutura complexa, anisotrópica, hierárquica e heterogénea, caracterizada por um excelente desempenho mecânico. Contudo, como se trata de um material quase frágil, inúmeras vezes acaba por fraturar. Estas fraturas diminuem a qualidade de vida do paciente e acarretam elevados custos para o sistema de saúde. Com vista ao tratamento destas fraturas, surgiu o projeto BoFraPla, que se propõe a desenvolver um sistema fibroso de fixação de fraturas ósseas. Assim, no âmbito das atividades deste projeto, surge a presente dissertação que se propõe a caracterizar mecanicamente a ligação entre o osso e um cimento ósseo. A partir de uma profunda revisão bibliográfica apurou-se que, apesar do cimento ósseo ser utilizado há mais de cinquenta anos, existem poucas referências à sua caracterização mecânica, não sendo encontrada nenhuma que fizesse uma clara caracterização do processo de fratura entre o osso e o cimento. Assim, neste relatório é apresentada uma caracterização em puro modo I (tensão), através de um ensaio Double Cantilever Beam (DCB) e outra caracterização em puro modo II (cisalhamento), através de um ensaio End-Notched Flexure (ENF). Para colmatar as dificuldades de monitorização do comprimento de fenda durante os ensaios laboratoriais, recorreu-se a um método baseado no comprimento de fenda equivalente. Com este método foi traçada a curva de resistência para cada provete, sendo notória a existência de patamares na sua maioria, o que permite uma correta medição da energia de fratura para cada ensaio. Com vista a validar os resultados obtidos, foram realizadas simulações numéricas com modelos coesivos. Através dos resultados, foi possível apurar que os ensaios escolhidos, as dimensões definidas e o procedimento adotado, podem ser utilizados para caracterizar à fratura entre estes dois materiais nos modos de carregamento estudados

Tauroursodeoxycholic Acid Drives Mitochondrial Bioenergetics Toward Neural Stem Cell Proliferation

Neurogenesis occurs throughout life in discrete areas of the adult mammalian brain. Unfortunately, there is a lack of effective regeneration during aging or after injury. Therefore, life-long potentiation of endogenous neurogenesis represents a major issue. Curiously, proliferation and differentiation potential of neural stem cells (NSCs) were recently shown to be highly dependent on mitochondrial bioenergetics and fatty acid (FA) lipogenesis. Furthermore, tauroursodeoxycholic acid (TUDCA), an endogenous neuroprotective bile acid, considered a regulator of energy metabolism and an inhibitor of early differentiation-associated apoptosis events in NSCs, stimulates proliferation and neuronal conversion of these cells. We aimed to clarify the impact of TUDCA on the mitochondrial proteome in self-renewing or differentiating mouse NSCs, using liquid chromatography coupled with mass spectrometry (LC-MS) based detection of differential proteomics. Validation of mitochondrial proteomic analysis by Western blot in two different NSC lines revealed that TUDCA significantly decreases the mitochondrial levels of long-chain acyl-CoA dehydrogenase (LCAD) protein upon differentiation, an enzyme crucial for β-oxidation of long-chain FAs. Further, nuclear levels of sterol regulatory element-binding protein (SREBP-1), a major transcription factor of lipid biosynthesis, were also found significantly increased, as the levels of palmitic and stearic FAs raise up. Interestingly, mitochondrial levels of pyruvate dehydrogenase E1-α (PDHE1-α), an enzymatic subunit belonging to glucose metabolism, were also markedly enhanced by TUDCA. Of note, TUDCA promoted mitochondria-nucleus translocation of PDHE1-α. Therefore, the proliferative role of this bile acid may rely, in part, in increasing the pool of mitochondrial and/or nuclear acetyl-CoA to assure NSC cycle progression. Finally, LCAD, SREBP-1, and PDHE1-α expression profiles were also assessed during early stages of neural differentiation bringing novel insights to NSC metabolic choices throughout differentiation. Altogether, our results unravel the metabolic impact of TUDCA in controlling NSC fate, demonstrating that this bile acid not only induces mitochondrial advantageous conditions but also metabolic plasticity

The pine wood nematode, Bursaphelenchus xylophilus, in Portugal: possible introductions and spread routes of a serious biological invasion revealed by molecular methods

The pine wood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), is a major world-wide pathogen and pest of pine, with impacts on forest health, natural ecosystem stability and international trade. In Portugal, PWN was first diagnosed in 1999, the first occurrence also for Europe. The disease was recently detected on the island ofMadeira and in northern Spain. In an attempt to search for more reliable and robust molecular markers that enable the study of intraspecific variability of B. xylophilus from different geographic locations, the intergenic spacer (IGS) region of the 5S rRNA gene and inter-simple sequence repeats (ISSR) analysis were used to determine the genetic relationships among 43 B. xylophilus isolates from Portugal, China, Japan, South Korea and USA. IGS sequence analysis showed that this region can only be used to establish interspecific relationships, since no differences were detected among Portuguese isolates from different geographic locations. Fingerprints obtained with ISSR show high genetic variability among Portuguese isolates, except for the ones obtained prior to 2008. The ISSR dendrogram suggests the spread of the disease inside continental Portugal and to Madeira. Until 2008, B. xylophilus populations found in continental Portugal showed low genetic diversity, pointing to a single introduction, probably from Asia, whereas recent populations from continental Portugal (2009-2010) and Madeira show high genetic diversity, suggesting multiple introductions from different origins

Rethinking the stylistic categories of Portuguese 19th Century Sculpture: The Work of António Teixeira Lopes

El artículo reflexiona sobre las categorías estilísticas de la escultura portuguesa del siglo XIX a partir del análisis de la obra de António Teixeira Lopes, considerado el principal representante del naturalismo escultórico de este país. En primer lugar, se aborda el concepto de naturalismo en la historia del arte portuguesa, ofreciendo una visión crítica sobre su separación en relación con el Romanticismo, a diferencia de la teoría dominante en la historiografía especializada sobre este tema. Al mismo tiempo, demostraremos la dificultad que entraña la aplicación de los conceptos de análisis de la pintura a la escultura cuando se analiza una obra de arte concreta. En segundo lugar, con el contexto artístico portugués como telón de fondo, se estudia la carrera académica y profesional de Teixeira Lopes. Finalmente, a partir del análisis de la obra del escultor y del conocimiento de sus métodos y puntos de vista sobre el arte, se cuestiona el etiquetado de Lopes como naturalista y se defiende la necesidad de una comprensión menos compartimentada del arte del siglo XIX

Paralytic shellfish toxins and ocean warming: bioaccumulation and ecotoxicological responses in jujvenile Gilthead Seabream (Sparus aurata)

Warmer seawater temperatures are expected to increase harmful algal blooms (HABs) occurrence, intensity, and distribution. Yet, the potential interactions between abiotic stressors and HABs are still poorly understood from ecological and seafood safety perspectives. The present study aimed to investigate, for the first time, the bioaccumulation/depuration mechanisms and ecotoxicological responses of juvenile gilthead seabream (Sparus aurata) exposed to paralytic shellfish toxins (PST) under different temperatures (18, 21, 24 °C). PST were detected in fish at the peak of the exposure period (day five, 0.22 µg g-1 N-sulfocarbamoylGonyautoxin-1-2 (C1 and C2), 0.08 µg g-1 Decarbamoylsaxitoxin (dcSTX) and 0.18 µg g-1 Gonyautoxin-5 (B1)), being rapidly eliminated (within the first 24 h of depuration), regardless of exposure temperature. Increased temperatures led to significantly higher PST contamination (275 µg STX eq. kg-1). During the trial, fish antioxidant enzyme activities (superoxide dismutase, SOD; catalase, CAT; glutathione S-transferase, GST) in both muscle and viscera were affected by temperature, whereas a significant induction of heat shock proteins (HSP70), Ubiquitin (Ub) activity (viscera), and lipid peroxidation (LPO; muscle) was observed under the combination of warming and PST exposure. The differential bioaccumulation and biomarker responses observed highlight the need to further understand the interactive effects between PST and abiotic stressors, to better estimate climate change impacts on HABs events, and to develop mitigation strategies to overcome the potential risks associated with seafood consumption.Agência financiadora European Union (EU) 678193 Portuguese Foundation for Science and Technology (FCT) IF/00253/2014 CEECIND/01739/2017 UID/Multi/04326/2019info:eu-repo/semantics/publishedVersio

The influence of chain orientation in the electric behaviour of polymer diodes

Recently some experimental results have showed that the spatial alignment of conjugated polymer chains on nanometre length scales can influence the behaviour of polymer-based electronic devices, such as light-emitting diodes, field effect transistors, and photovoltaic cells. The effects of chain orientation at electrode-polymer interfaces on the charge injection process and charge mobility through the polymer layer are not well understood. In this work we use a generalized dynamical Monte Carlo method to study the influence of different polymer chain orientation relative to the electrodes surface on the electric behaviour of single-layer polymer diode, namely density current and charge density.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/CTM/41574/2001; CONC-REEQ/443/EEI/2005; SFRH/BD/22143/2005FEDE

Time perception deficits in impulsivity disorders: A systematic review

This systematic review aims to identify evidences of distortions in time perception (TP) in people with impulsiv ity disorders or other conditions having impulsivity traits, namely traumatic brain injuries, certain personality disorders, addictive behavior disorders, and pathological gambling. Studies related to TP deficits and impulsivity disorders were retrieved from multiple literature databases, through predefined inclusion and exclusion criteria. From the 197 obtained documents, 47 were selected for analysis, and a final set of 15 studies was retrieved for this review. Regardless of some conflicting findings, the available results suggest that patients with orbitofrontal lesions produce and reproduce significantly less time and estimate time periods significantly longer than healthy subjects. Patients with borderline personality disorder show decreased time perception and patients with antisocial personality disorder seem to execute more premature responses during time estimation tasks. Stimulant dependent individuals also tend to overestimate the time intervals, and pathological gamblers demonstrate shorter time horizons than social gamblers. Taken together, the available data suggest that impulsive individuals tend to overestimate the passage of time and to execute more premature responses, producing and reproducing less time, but more research is necessary to increase the strength of the evidences on this issue. This systematic review updates evidences of distortions in TP in impulsivity, improving the understanding of the relations between these two variables.info:eu-repo/semantics/publishedVersio

Effectiveness of a commercial peracetic acid-based disinfectant to reduce microbial loads in spinach (spinacia oleracea) leaves

The growing consumption trends of healthy and easy to prepare foods have stimulated the minimally processed ready-to-eat (RTE) vegetable market[1]. Besides providing health benefits, the consumption of minimally processed leafy leaves has been associated with the presence of foodborne pathogens, such as Listeria monocytogenes[2-4]. Contamination of leafy vegetables can occur at any step through the food chain, and therefore, their washing with sanitizers improves their safety. However, the effectiveness of the process can be influenced by the washing parameters (e.g., water temperature and contact time of vegetables with disinfectant solution), sanitizers used (e.g., chlorine-based or organic acid), vegetables, phyllosphere bacterial community composition on a leafy surface, and also microorganisms’ characteristics, such as the target genus and cell attachment (e.g., adhesion to biofilm and plant internalization)[5].info:eu-repo/semantics/publishedVersio

Resistência à mudança e stress percebido em relação à Covid-19

Dissertação de mestrado em Psicologia ClínicaExame público realizado em 18 de julho de 2023, às 15HEm Portugal, os primeiros casos de infeção por coronavírus surgiram a dois de março de 2020, na cidade do Porto. A partir desse momento, várias medidas foram implementadas para tentar conter a disseminação do vírus. Muitas dessas medidas impuseram mudanças drásticas no quotidiano das pessoas. Vários estudos têm documentado que esta pandemia global esteve associada a um aumento da prevalência de problemas de saúde mental na população. Com o objetivo geral de aprofundar o conhecimento sobre os fatores psicológicos que podem ter representado um risco para os problemas de saúde mental neste período, o presente estudo transversal procurou avaliar a relação entre o traço Resistência à Mudança e o Stress Percebido em Relação à Covid-19. O estudo contou com uma amostra de 477 participantes adultos. Os instrumentos de avaliação utilizados foram a Escala de Resistência à Mudança (RTC), o Questionário de Perceção de Doença Covid-19 (IPQ-B-C) e um Questionário Sociodemográfico. Uma análise multivariada revelou que uma elevada Resistência à Mudança está geralmente associada a um aumento de Stress Percebido em Relação à Covid-19. No entanto, quando analisadas as dimensões individuais do IPQ-B-C, verificou-se que a Resistência à Mudança estava significativamente associada aos domínios emocionais (Preocupação e Resposta Emocional), mas não aos domínios cognitivos. Para além disso, efetuaram-se comparações poste-hoc de médias marginais com as variáveis sociodemográficas, revelando que os homens e as mulheres diferiam significativamente nas componentes emocionais do stress. Especificamente, as mulheres apresentaram níveis mais elevados de Stress Percebido em Relação à Covid-19 do que os homens, mesmo depois do controlo da Resistência à Mudança.The first cases of coronavirus disease (COVID-19) infection emerged in Portugal on March 2, 2020, in the city of Porto, and this was followed by the implementation of various measures to contain the spread of the virus. Many of these measures imposed drastic changes to people´s daily lives. Various studies have documented that this global pandemic was linked to increase in the prevalence of mental health problems among the population. Whit the broad aim of building knowledge of the psychological factos that may have posed a risk for mental health problems in this period, this cross-sectional study sought to evaluate the relationship between trait Resistance to Change and Covid-19 related Stress. The study comprised a sample of 477 adult participants. The evaluation instruments used were the Resistance to Change Scale (RTC), the Covid-19 Illness Perception Questionnaire (IPQ-B-C) and a sociodemographic questionnaire. A multivariate analysis indicated that high Resistance to Change was generally associated with increased Covid-19 related Stress. However, when analyzing the individual dimensions of the IPQ-B-C it was found that Resistance to Change was significantly associated with the emotional (Worry and Emotional Response) but not cognitive domains. Furthermore, post-hoc comparisons of estimated marginal means were conducted with sociodemographic variables, revealing men and women differed significantly in the emotional components of stress. Specifically, women exhibited higher levels of Covid-19 related Stress than men, even after controlling for Resistance to Change