Fracture-based interface model for NSM FRP systems in concrete

This paper introduces a numerical simulation tool using the Finite Element Method (FEM) for near-surface mounted (NSM) strengthening technique using fibre reinforced polymers (FRP) applied to concrete elements. In order to properly simulate the structural behaviour of NSM FRP systems there are three materials (concrete, FRP and the adhesive that binds them) and two interfaces (FRP/adhesive and adhesive/concrete) that shall be considered. This work presents the major details of a discontinuous-based constitutive model which aims at simulating NSM FRP interfaces implemented in the FEMIX FEM software. This constitutive model was adapted from one available in the literature, originally employed for fracture simulation in meso-scale analyses of quasi-brittle materials, which is based on the classical Flow Theory of Plasticity combined with fracture mechanics concepts. The most important features of the implemented constitutive model are the consideration of both fracture modes I and II and the possibility of performing 2D and 3D analysis. In the end, results based on FEM simulations are presented with the aim of investigating the soundness and accuracy of the constitutive model to simulate NSM FRP systems’ interfaces

A review on the bond behavior of FRP NSM systems in concrete

This paper presents a review of current knowledge on the bond behavior of fiber reinforced polymer (FRP) systems inserted in the cover of concrete elements, commonly known as the near-surface mounted technique (NSM). In the first part, by studying the physics of the phenomenon, the typical failure modes, the most common bond tests and two of the most important design guidelines for FRP NSM systems are introduced. In the second part, a database of bond tests composed by 431 records is presented and the accuracy of existing design guidelines is assessed with this data. Lastly, the formulations proposed by these design guidelines are recalibrated based on the experimental results in the database.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT (Portuguese Foundation for Science and Technology) under the project CutInDur PTDC/ECM/11 2396/2009. The first author wishes also to acknowledge the Grant No. SFRH/BD/87443/2012 provided by FCT

Estudo comparativo entre modelos de previsão de resistência: leis analíticas versus data mining

Neste trabalho apresenta-se um estudo comparativo entre modelos de previsão da resistência de sistemas de polímeros reforçados com fibras (Fiber Reinforced Polymers – FRP) inseridos no betão de recobrimento de elementos de betão. Esta técnica é conhecida por Near-Surface Mounted (NSM). São analisados dois dos mais importantes códigos de projeto existentes e ainda modelos obtidos com recurso a algoritmos de data mining (DM). Os resultados obtidos demonstram que o recurso ao DM pode ser uma alternativa viável aos códigos existentes na previsão da resistência da ligação de sistemas FRP NSM

Determination of parathion in biological fluids by means of direct Solid Phase Microextraction.

A new and simple procedure for the determination of parathion in human whole blood and urine using direct immersion (DI) solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) is presented. This technique was developed using only 100 ìL of sample, and ethion was used as internal standard (IS). A 65-ìm Carbowax/divinylbenzene (CW/DVB) SPME fibre was selected for sampling, and the main parameters affecting the SPME process such as extraction temperature, adsorption and desorption time, salt addition, agitation and pH effect were optimized to enhance the sensitivity of the method. This optimization was also performed to allow the qualitative determination of parathion’s main metabolite, paraoxon, in blood. The limits of detection and quantitation for parathion were 3 and 10 ng/mL for urine and 25 and 50 ng/mL for blood, respectively. For paraoxon, the limit of detection was 50 ng/mL in blood. The method showed linearity between the LOQ and 50 ìg/mL for both matrices, with correlation coefficients ranging from 0.9954 to 0.9999. Precision and accuracy were in conformity with the criteria normally accepted in bioanalytical method validation. The mean absolute recoveries were 35.1% for urine and 6.7% for blood. Other parameters such as dilution of sample and stability were also validated. Its simplicity and the fact that only 100 ìL of sample is required to accomplish the analysis make this method useful in forensic toxicology laboratories to determine this compound in intoxications, and it can be considered an alternative to other methods normally used for the determination of this compound in biological media

Designing NSM FRP systems in concrete using partial safety factors

This paper presents design procedures for fibre reinforced polymer (FRP) systems inserted in the cover of concrete elements according to the near-surface mounted (NSM) technique. Such strengthening system depends greatly on their bond strength. Two existing design formulations to estimate the bond strength of NSM FRP systems in concrete are studied. A reliability analysis is conducted with the purpose of making the design formulations consistent with the partial safety factors philosophy, including the Eurocodes. Hence, the necessary probabilistic distributions are calibrated based on a large database of bond tests. The results presented herein show that the existing guidelines can be extended and adopted under the framework of the Eurocodes. However, mainly due to their limitations in addressing individually all the possible failure modes, the variability of the probabilistic distributions found are quite high, leading to high partial coefficients of safety. Thus, in the future, new and improved formulations should be developed

Short-Term Biochemical Biomarkers of Stress in the Oyster Magallana angulata Exposed to Gymnodinium catenatum and Skeletonema marinoi

Additionally, this work was also co-funded by the MAR2020, Portugal 2020 and the European Union EMFF projects (MAR-02.01.01-FEAMP-0050, MAR-02.01.01-FEAMP-0051 and MAR-01.03.02-FEAMP-0013). Publisher Copyright: © 2023 by the authors.Bivalves accumulate toxins produced by microalgae, thus becoming harmful for humans. However, little information is available about their toxicity to the bivalve itself. In the present work, the physiological stress and damage after the ingestion of toxic dinoflagellate species (Gymnodinium catenatum) and a diatom species (Skeletonema marinoi, which is non-toxic to humans but may be to grazers) in the oyster Magallana angulata are evaluated against a control treatment fed with the chlorophyte Tetraselmis sp. Oysters were exposed for two hours to a concentration of 4 × 104 cells/L of G. catenatum and 2 × 107 cells/L of S. marinoi. The biomarkers superoxide dismutase (SOD), catalase (CAT), glutathione S-Transferase, total Ubiquitin (Ubi) and Acetylcholinesterase (AchE) were assessed. The exposure of M. angulata to G. catenatum lead to a reduction in SOD and AchE activity and ubiquitin concentrations when compared to the control treatment. Moreover, it increased CAT activity in the adductor muscle, and maintained its activity in the other tissues tested. This may be related to the combination of reduced metabolism with the deployment of detoxification processes. S. marinoi also lead to a decrease in all biomarkers tested in the gills and digestive glands. Therefore, both species tested caused physiological alterations in M. angulata after two hours of exposure.publishersversionpublishe

Screening analysis of biodiesel feedstock using UV-vis, NIR and synchronous fluorescence spectrometries and the successive projections algorithm

This paper investigates the use of UV-vis, near infrared (NIR) and synchronous fluorescence (SF) spectrometries coupled with multivariate classification methods to discriminate biodiesel samples with respect to the base oil employed in their production. More specifically, the present work extends previous studies by investigating the discrimination of corn-based biodiesel from two other biodiesel types (sunflower and soybean). Two classification methods are compared, namely full-spectrum SIMCA (soft independent modelling of class analogies) and SPA-LDA (linear discriminant analysis with variables selected by the successive projections algorithm). Regardless of the spectrometric technique employed, full-spectrum SIMCA did not provide an appropriate discrimination of the three biodiesel types. In contrast, all samples were correctly classified on the basis of a reduced number of wavelengths selected by SPA-LDA. It can be concluded that UV-vis, NIR and SF spectrometries can be successfully employed to discriminate corn-based biodiesel from the two other biodiesel types, but wavelength selection by SPA-LDA is key to the proper separation of the classes.Fil: Insausti, Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Gomes, Adriano A.. Universidade Federal da Paraíba; BrasilFil: Cruz, Fernanda V.. Universidade Federal da Paraíba; BrasilFil: Pistonesi, Marcelo Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ugulino de Araújo, Mário C.. Universidade Federal Da Paraíba; BrasilFil: Galvão, Roberto K.H.. Universidade Federal da Paraíba; BrasilFil: Pereira, Claudete F.. Universidade Federal da Paraíba; BrasilFil: Fernández Band, Beatriz Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Escalas de Qualidade de Vida Após Amputação Major do Membro Inferior em Cirurgia Vascular: Revisão da Literatura

Introdução: Apesar dos esforços das equipas de saúde, a taxa da amputação em doentes com Isquémia Crítica Ameaçadora de Membro (CLTI) é bastante elevada. Cada vez mais se torna relevante um tratamento individualizado do doente por forma a melhorar a sua qualidade de vida. Contudo, não existe uma escala de qualidade de vida validada para doentes amputados por isquémia crítica. Os autores propõem uma revisão sistemática da literatura com vista a sumarizar as escalas de avaliação de qualidade de vida após amputação. Métodos: Foi feita uma pesquisa por todos os estudos relacionados com avaliação funcional e da qualidade de vida após amputação na base de dados Pubmed. Resultados: Dos 228 artigos foram incluídos 28. Dos artigos analisados apenas 3 avaliaram exclusivamente doentes vasculares com CLTI. 24 escalas diferentes foram usadas 44 vezes: 11 escalas (44%) de avaliação de saúde e 14 escalas (56%) de qualidade de vida, das quais 2 escalas (18%) de avaliação de saúde e 4 das escalas (29%) de qualidade de vida são específicas para doentes amputados e uma escala para doença arterial periférica. Conclusões: A heterogeneidade de escalas torna difícil uma comparação de resultados. Na população de doentes amputados vasculares, escalas gerais podem não ser representar corretamente os domínios mais valorizados por esta população. Escalas específicas para protetisados ou de avaliação da progressão de doença arterial periférica também parecem não ser as mais adequadas para este subtipo de doentes mais idosos e com limitações prévias. São essenciais novos estudos para validar uma escala específica para esta população

Combining geostatistical and biotic interaction modelling to predict amphibian refuges under crayfish invasion across dendritic stream networks

Biodiversity ResearchAim: Biological invasions are pervasive in freshwater ecosystems, often causing native species to contract into areas that remain largely free from invasive species impacts. Predicting the location of such ecological refuges is challenging, because they are shaped by the habitat requirements of native and invasive species, their biotic interactions, and the spatial and temporal invasion patterns. Here, we investigated the spatial distribution and environmental drivers of refuges from invasion in river systems, by considering biotic interactions in geostatistical models accounting for stream network topology. We focused on Mediterranean amphibians negatively impacted by the invasive crayfishes Procambarus clarkii and Pacifastacus leniusculus. Location: River Sabor, NE Portugal. Methods: We surveyed amphibians at 168 200-m stream stretches in 2015. Geostatistical models were used to relate the probabilities of occurrence of each species to environmental and biotic variables, while controlling for linear (Euclidean) and hydrologic spatial dependencies. Biotic interactions were specified using crayfish probabilities of occurrence extracted from previously developed geostatistical models. Models were used to map the distribution of potential refuges for the most common amphibian species, under current conditions and future scenarios of crayfish expansion. Results: Geostatistical models were produced for eight out of 10 species detected, of which five species were associated with lower stream orders and only one species with higher stream orders. Six species showed negative responses to one or both crayfish species, even after accounting for environmental effects and spatial dependencies. Most amphibian species were found to retain large expanses of potential habitat in stream headwaters, but current refuges will likely contract under plausible scenarios of crayfish expansion. Main conclusions: Incorporating biotic interactions in geostatistical modelling provides a practical and relatively simple approach to predict present and future distributions of refuges from biological invasion in stream networks. Using this approach, our study shows that stream headwaters are key amphibian refuges under invasion by alien crayfishinfo:eu-repo/semantics/publishedVersio