261 research outputs found

    Geometry Optimization for Miniaturized Thermoelectric Generators

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    Thermoelectric materials capable of converting heat into electrical energy are used in sustainable electric generators, whose efficiency has been normally increased with incorporation of new materials with high figure of merit (ZT) values. Because the performance of these thermoelectric generators (TEGs) also depends on device geometry, in this study we employ the finite element method to determine optimized geometries for highly efficient miniaturized TEGs. We investigated devices with similar fill factors but with different thermoelectric leg geometries (filled and hollow). Our results show that devices with legs of hollow geometry are more efficient than those with filled geometry for the same length and cross-sectional area of thermoelectric legs. This behavior was observed for thermoelectric leg lengths smaller than 0.1 mm, where the leg shape causes a significant difference in temperature distribution along the device. It was found that for reaching highly efficient miniaturized TEGs, one has to consider the leg geometry in addition to the thermal conductivity

    Avaliação Nutricional de um Suplemento Alimentar

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    A escolha da nutrição mais adequada tem sido um tema estudado com grande interesse ao longo da história da humanidade tendo em conta a manutenção da Saúde, mas igualmente com outras finalidades como o atraso do envelhecimento ou outros benefícios. O desafio colocado pela ingestão de frutos, vegetais, cereais, azeite e vinho aplicado pela intitulada Dieta Mediterrânica torna possível o entendimento de países com diversas etnias, culturas, economia e religiões, todos eles à volta do mar Mediterrâneo. Por outro lado, o contínuo aparecimento de patologias como os acidentes vasculares cerebrais, o cancro e a aterosclerose podem ser de algum modo minimizadas pela ingestão de alguns compostos bioativos presentes nos alimentos, os chamados nutracêuticos e alimentos funcionais. O objetivo deste trabalho foi fazer uma revisão dos estudos publicados sobre os efeitos do licopeno na saúde humana, uma abordagem da respetiva química, fontes, biodisponibilidade e do potencial possível papel e mecanismos desempenhado na prevenção de determinadas doenças crónicas e no cancro. O licopeno é um dos antioxidantes mais potentes conhecidos, constituindo porventura o carotenóide mais importante presente na dieta, maioritariamente fornecido através do tomate e derivados. Atendendo a que o organismo humano não consegue sintetizar este composto de novo, este tem obrigatoriamente que ser fornecido pela dieta. No entanto, a sua biodisponibilidade pode ser afetada por inúmeros fatores tais como a forma de digestão da matriz alimentar, a temperatura de confecção, pela presença de outras gorduras no alimento, dosagem e outros compostos solúveis, incluindo os outros carotenóides. Esses fatores causam a libertação de licopeno a partir da matriz de alimentos e alteram assim a sua biodisponibilidade.info:eu-repo/semantics/publishedVersio

    A systematic review and bibliometric analysis of wildland fire behavior modeling

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    Wildland fires have become a major research subject among the national and international research community. Different simulation models have been developed to prevent this phenomenon. Nevertheless, fire propagation models are, until now, challenging due to the complexity of physics and chemistry, high computational requirements to solve physical models, and the difficulty defining the input parameters. Nevertheless, researchers have made immense progress in understanding wildland fire spread. This work reviews the state-of-the-art and lessons learned from the relevant literature to drive further advancement and provide the scientific community with a comprehensive summary of the main developments. The major findings or general research-based trends were related to the advancement of technology and computational resources, as well as advances in the physical interpretation of the acceleration of wildfires. Although wildfires result from the interaction between fundamental processes that govern the combustion at the solid- and gas-phase, the subsequent heat transfer and ignition of adjacent fuels are still not fully resolved at a large scale. However, there are some research gaps and emerging trends within this issue that should be given more attention in future investigations. Hence, in view of further improvements in wildfire modeling, increases in computational resources will allow upscaling of physical models, and technological advancements are being developed to provide near real-time predictive fire behavior modeling. Thus, the development of two-way coupled models with weather prediction and fire propagation models is the main direction of future work.This work was supported by the Portuguese Foundation for Science and Technology (FCT) within the R&D Units Project Scope UIDB/00319/2020 (ALGORITMI) and R&D Units Project Scope UIDP/04077/2020 (METRICS) and through project: PCIF/GRF/0141/2019: “O3F—An Optimization Framework to reduce Forest Fire

    Ecotoxicity variation through parabens degradation by single and catalytic ozonation using volcanic rock

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    Parabens are widely used as antimicrobial and preservative ingredients in pharmaceutical and personal care products. Nevertheless, these compounds have been increasingly seen as emerging contaminants that can be toxic to a wide range of species. In this study, the toxic effect of a mixture of parabens (10 mg/L of each paraben: methyl-, ethyl-, propyl-, benzyl- and butylparaben) and its degradation products through single and catalytic ozonation (using volcanic rock as low-cost catalyst) was investigated over several non-target species: cladocerans, microalgae, clams, macrophytes and cress. The analysis of the toxicity of parabens mixture is relevant since usually these compounds are used as blends rather than individually. While parabens were totally removed both by single and catalytic ozonation the toxicity of the samples resulting from both treatments was generally high. This toxicity was still compared to the one obtained for several dilutions of the initial parabens mixture and it was concluded that the by-products formed are more toxic than the most diluted parabens mixture sample (0.625 mg/L). While catalytic ozonation allows reducing the amount of ozone (about 3-fold) required for total removal of parabens, the resulting treated solution was more toxic than the sample taken at the endpoint of the single ozonation treatment. This suggests that the highest amount of ozone used for single ozonation allowed the elimination of toxic by-products such as hydroquinone and 1,4-benzoquinone. Still, the effect of by-products and parabens interaction depends on the species analyzed due to their different tolerances to potentially toxic products.publishe

    X-linked Adrenal Hypoplasia Congenita: report of two families and a new NR0B1 mutation

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    Background: X-linked Adrenal Hypoplasia Congenita (X-linked AHC) tipically manifests as adrenal insufficiency in a bimodal clinical presentation (5–60 days and 2–13 years) and, at pubertal age, hypogonadotropic hypogonadism (HH) in males. It is caused by mutations in NR0B1 (present in Xp21.2), a gene with a critical role in the development of adrenals and hypothalamic-pituitary-gonadal (HPG) axis. It represents ~1% of all causes of primary adrenal insufficiency under age 18. We present two kindreds with NR0B1 mutations, one with a previously unreported mutation. Clinical case - family A: The proband presented with adrenal crisis at day 18 of life. Family history was relevant for an uncle death as a newborn. Hormonal assays revealed elevated ACTH (34,5 pmol/L, reference: T, leading to a premature stop codon, p.Lys362*, in exon 1. His mother and sister were both asymptomatic carriers for this mutation. This mutation, not described previously, leads probably to a non-functional truncated protein. Clinical case - family B: Kindred B had two males who presented with adrenal crisis at the newborn age (proband: 14 days; brother: 16 days). At 6 months of age, the proband had elevated ACTH (193.2 pmol/L, reference: G; p.Tyr81*, in exon 1, present in the two affected males. His mother and one sister were also asymptomatic carriers. Conclusion: Our kindreds highlights the clinical aspects of the rare X-linked AHC and its challenging differential diagnosis. The diagnosis was based on …. Completar … and an apparently X-linked mode of inheritance. Molecular analysis of the NR0B1 gene allowed the identification of the molecular defect in both families. Two different nonsense mutation in exon 1 were identified, giving rise most probably to truncated non-functional proteins, confirming the disease severity or the clinical phenotype of the affected boys. Mutation identification was relevant for genetic counseling of the parents, as well as for the patient’s sisters

    Magnetic field strength and orientation effects on Co-Fe discontinuous multilayers close to percolation

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    Magnetization and magnetoresistance in function of the magnitude and orientation of applied magnetic field were studied in Co-Fe discontinuous multilayers close to their structural percolation. The high pulsed magnetic fields up to 33 T were used in the 120–310 K temperature range. Comparison between longitudinal and transverse (with respect to the film plane) field configurations was made in the low-field and high-field regimes in order to clarify the nature of the measured negative magnetoresistance. Coexistence of two distinct magnetic fractions, superparamagnetic (SPM, consisting of small spherical Co-Fe granules) and superferromagnetic (SFM, by bigger Co-Fe clusters), was established in this system. These fractions were shown to have different relevance for the system magnetization and magnetotransport. While the magnetization is almost completely (up to ∼97%) defined by the SFM contribution and practically independent of temperature (in this range), the magnetoresistance experiences a crossover from a regime dominated by Langevin correlations (suppressed with temperature) between neighbor SPM and SFM moments at low fields, to that dominated by spin scattering (enhanced with temperature) of charge carriers within SFM clusters at high fields. Also, the demagnetizing effects, sensitive to the field orientation, were found to essentially define the low-field behavior and characteristic crossover field

    Cysteine Boosts Fitness Under Hypoxia-Mimicked Conditions in Ovarian Cancer by Metabolic Reprogramming

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    Funding Information: Funding. This research was supported by Funda??o para a Ci?ncia e Tecnologia (FCT) (Ph.D. ProRegeM program, Ref: PD/BD/105893/2014; FCT individual Ph.D. fellowship Ref: 2020.06956.BD) and iNOVA4 Health (Project 4 and Project 21). iNOVA4Health-UID/Multi/04462/2013 is a program financially supported by Funda??o para a Ci?ncia e Tecnologia/ Minist?rio da Educa??o e Ci?ncia, through national funds. The authors would like to acknowledge the Instituto Portugu?s de Oncologia de Lisboa Francisco Gentil (IPOLFG) for partially funding the project. Publisher Copyright: © Copyright © 2021 Nunes, Ramos, Santos, Mendes, Silva, Vicente, Pereira, Félix, Gonçalves and Serpa.Among gynecologic malignancies, ovarian cancer is the third most prevalent and the most common cause of death, especially due to diagnosis at an advanced stage together with resistance to therapy. As a solid tumor grows, cancer cells in the microenvironment are exposed to regions of hypoxia, a selective pressure prompting tumor progression and chemoresistance. We have previously shown that cysteine contributes to the adaptation to this hypoxic microenvironment, but the mechanisms by which cysteine protects ovarian cancer cells from hypoxia-induced death are still to be unveiled. Herein, we hypothesized that cysteine contribution relies on cellular metabolism reprogramming and energy production, being cysteine itself a metabolic source. Our results strongly supported a role of xCT symporter in energy production that requires cysteine metabolism instead of hydrogen sulfide (H2S) per se. Cysteine degradation depends on the action of the H2S-synthesizing enzymes cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and/or 3-mercaptopyruvate sulfurtransferase (MpST; together with cysteine aminotransferase, CAT). In normoxia, CBS and CSE inhibition had a mild impact on cysteine-sustained ATP production, pointing out the relevance of CAT + MpST pathway. However, in hypoxia, the concomitant inhibition of CBS and CSE had a stronger impact on ATP synthesis, thus also supporting a role of their hydrogen sulfide and/or cysteine persulfide-synthesizing activity in this stressful condition. However, the relative contributions of each of these enzymes (CBS/CSE/MpST) on cysteine-derived ATP synthesis under hypoxia remains unclear, due to the lack of specific inhibitors. Strikingly, NMR analysis strongly supported a role of cysteine in the whole cellular metabolism rewiring under hypoxia. Additionally, the use of cysteine to supply biosynthesis and bioenergetics was reinforced, bringing cysteine to the plateau of a main carbon sources in cancer. Collectively, this work supports that sulfur and carbon metabolism reprogramming underlies the adaptation to hypoxic microenvironment promoted by cysteine in ovarian cancer.publishersversionpublishe
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