Comportamento das interfaces solo - geossintético

Tese de mestrado integrado. Engenharia Civil. Faculdade de Engenharia. Universidade do Porto. 201

Improved performance of geosynthetics enhanced ballast: laboratory and numerical studies

Ballasted rail tracks form one of the most important worldwide transportation modes in terms of traffic tonnage, serving the needs of bulk freight and passenger movement. High impact and cyclic loads can cause a significant deformation leading to poor track geometry. In order to mitigate these problems, the concept of the inclusion of geosynthetics in rail tracks is introduced. This paper presents the current state-of-the-art knowledge of rail track geomechanics, including results obtained from laboratory testing, field investigations and numerical modelling to study the load-deformation behaviour of ballast improved by geosynthetics. The shear stress-strain and deformation behaviour of geosynthetic-reinforced ballast are investigated in the laboratory using a large-scale direct shear test device, a track process simulation apparatus and a drop-weight impact testing equipment. Computational modelling using the discrete-element method is employed to simulate geosynthetic-reinforced ballasted tracks, capturing the discrete nature of ballast aggregates when subjected to various types of loading and boundary conditions. Discreteelement modelling is also used to conduct micromechanical analysis at the interface between ballast and geogrid, providing further insight into the behaviour of ballast subjected to cyclic loadings. These results provide promising approaches to incorporate into existing track design routines catering for future high-speed trains and heavier heavy hauls

Brazilian woods in Portuguese xylarium / Madeiras brasileiras em xilotecas portuguesas

The geographical origin of the wood samples in xylotheques (xylaria, wood collections) are part of the history of knowledge on the biodiversity of a given region. Portugal was the colonizer of Brazil and the transport of wood from the 16th century onwards played a significant part in the relationship of the two countries. This prompted the present study which has the following aims; to survey existing Portuguese xylotheques, identify their samples of Brazilian woods and thus contribute to future studies concerning the origin and distribution of species of Brazil's tropical forests, analyse and characterise the different kinds of wood collection surveyed, as well as identify some woods described by means of data obtained from interviews. Sixteen xylotheques were identified and investigated in Portugal and a survey of the Brazilian species contained in them was carried out. These xylotheques were of qualitatively different types: scientific, technological, expository or historical. It was also observed that the concept of a xylarium in Portugal varies from a simple collection of wood samples in cabinet or a box, to a physical space of larger dimensions reserved specifically for the storage of samples or collections. A total of 3,126 Brazilian wood samples were found. Despite the many expeditions carried out from the 16th century and the numerous shipments of woods sent from Brazil to Portugal, especially from the 18th century onwards, no samples derived from them were identified except in historical xylarium. Instead it was found that most Brazilian samples had been obtained through donations and exchange with Brazilian institutions. In contrast, the African wood samples had been obtained by expeditions undertaken by Portuguese institutions from the 20th century onwards. This can be explained by the emergence only in that century of specialized laboratories. By then it had been recognized in Portugal that due to the increase in global consumption of wood, there was a need to develop technological and scientific expertise on such a valuable resource, and consequently in 1948 the Board of Overseas Scientific Investigations decided to set up the Laboratory of Wood Histology and Technology, with well-defined objectives.

Comparison of zinc oxide nanoparticle integration into non-woven fabrics using different functionalisation methods for prospective application as active facemasks

The development of advanced facemasks stands out as a paramount priority in enhancing healthcare preparedness. In this work, different polypropylene non-woven fabrics (NWF) were characterised regarding their structural, physicochemical and comfort-related properties. The selected NWF for the intermediate layer was functionalised with zinc oxide nanoparticles (ZnO NPs) 0.3 and 1.2wt% using three different methods: electrospinning, dip-pad-dry and exhaustion. After the confirmation of ZnO NP content and distribution within the textile fibres by morphological and chemical analysis, the samples were evaluated regarding their antimicrobial properties. The functionalised fabrics obtained via dip-pad-dry unveiled the most promising data, with 0.017 ± 0.013wt% ZnO NPs being mostly located at the fibre’s surface and capable of total eradication of Staphylococcus aureus and Escherichia coli colonies within the tested 24 h (ISO 22196 standard), as well as significantly contributing (**** p < 0.0001) to the growth inhibition of the bacteriophage MS2, a surrogate of the SARS-CoV-2 virus (ISO 18184 standard). A three-layered structure was assembled and thermoformed to obtain facemasks combining the previously chosen NWF, and its resulting antimicrobial capacity, filtration efficiency and breathability (NP EN ISO 149) were assessed. The developed three-layered and multiscaled fibrous structures with antimicrobial capacities hold immense potential as active individual protection facemasks.FCT -Fundação para a Ciência e a Tecnologia(LA/P/0029/2020)info:eu-repo/semantics/publishedVersio

Hemofilia adquirida A e B principais apresentações clínicas da doença de Pott em crianças: Hemofilia adquirida A e B main clinical presentations of Pott disease in children

A hemofilia é uma doença sanguínea caracterizada por distúrbios nos mecanismos de coagulação do sangue, podendo ser de origem hereditária ou adquirida. A hemofilia adquirida ocorre devido à produção de autoanticorpos contra a atividade pró-coagulante dos fatores VIII (Hemofilia A) e IX (Hemofilia B). O objetivo desse trabalho é a realização de um estudo observacional e exploratório sobre os artigos publicados nos últimos 5 anos sobre a hemofilia adquirida A e B, uma vez que é uma enfermidade considerada rara. Dos 68 resultados obtidos na pesquisa, apenas 7 abordaram de forma objetiva sobre o tema, sendo utilizados na confecção do estudo. Segundo a literatura, as manifestações clínicas envolvem sangramento mucocutâneo, urogenital e gastrointestinal, e são mais prevalentes em idosos. Em crianças, o sangramento pode ser menos expressivo, provocando dúvidas quanto ao diagnóstico. O tratamento da hemofilia envolve a reposição dos fatores de coagulação deficientes e o uso de imunossupressores, ainda que nas obras analisadas apenas o tratamento hemostático tenha sido descrito, revelando uma carência de estudos sobre o uso de imunossupressores nos casos de hemofilia adquirida

Sepse: avaliação da qualidade do atendimento em setor de urgência e emergência: Sepsis: assessment of the quality of emergency and emergency care

A Sepse corresponde à presença de uma disfunção orgânica fatal provocada por uma resposta anormal do hospedeiro a um processo infeccioso, que pode progredir para um choque séptico. No decorrer dessa pesquisa, cuja metodologia foi a revisão integrativa de literatura, foram utilizados artigos científicos publicados em periódicos nacionais entre os anos de 2015 e 2022, retirados da base de dados Medline e Lilacs, sendo buscados a partir dos descritores: “Sepse”, “Qualidade do atendimento” e “Urgência e Emergência”. Com o objetivo de analisar a efetividade das ações de cuidados de Enfermagem aplicadas ao sepse adulto, a partir da análise de dados reunidos nesta revisão integrativa, foi possível concluir que a implantação de protocolos para o tratamento resultou em melhorias significativas nos indicadores de qualidade nos cuidados com a sepse, a exemplo da melhoria do fluxo e de atenção aos pacientes e redução da mortalidade nos setores de urgência e emergência

Use of synthetic inclusions for enhanced behaviour of railway ballast under impact loading

Ballasted rail tracks form one of the largest worldwide networks catering to passenger and freight transportation. However, track deterioration associated with severe dynamic wheel loads is inevitable over the years leading to high maintenance costs. Geosynthetics and energy-absorbing rubber mats have increasingly been applied in rail track foundations to improve track stability and reduce the life-cycle cost of the railway system. This paper presents the results of an experimental study carried out using a high-capacity drop-weight impact testing apparatus to investigate the deformation and degradation response of railway ballast under impact loading conditions. The effectiveness of the geogrid reinforcement in attenuating impact-induced damage and the enhanced ballast performance achieved by the simultaneous use of geogrid and rubber mats are evaluated and discussed. Test results have shown that the use of a biaxial geogrid at the ballast-subballast interface may be an effective way of reducing the ballast deformation and degradation under impact loading. However, the provision of rubber mats at the bottom of the ballast bed and a geogrid layer at 100 mm height was found to be an optimised solution for minimising the ballast permanent strains and the breakage of aggregates upon successive impact blows

Deformation and degradation response of railway ballast under impact loading - effect of artificial inclusions

Impact forces induced by wheel and/or rail irregularities and abrupt variations in track stiffness may lead to accelerated deterioration of the track components. The use of artificial inclusions such as geosynthetics and rubber-based energy absorbing mats can be an effective way of mitigating ballast degradation and improving the overall track performance. This paper describes a laboratory study carried out using a large-scale drop-weight impact testing apparatus to investigate the deformation and degradation behaviour of railway ballast under impact loading conditions. The effect of artificial inclusions (i.e., rubber mat and geogrid reinforcement) on the ballast response along repetitive impact blows is evaluated and discussed. Results have shown that the ballast deformations are particularly significant along the initial stage of impact loading, which is associated with ballast reorientation and rearrangement and corner breakage of ballast particles. Among the test conditions analysed in the current study, placement of rubber mats at the base of the ballast assembly and a geogrid layer at 100 mm height was found to be the best combination, providing the maximum reduction in the impact-induced ballast strains and particle breakage when compared to those obtained in the absence of artificial inclusions

Application of geoinclusions for sustainable rail infrastructure under increased axle loads and higher speeds

Given the ongoing demand for faster trains for carrying heavier loads, conventional ballasted railroads require considerable upgrading in order to cope with the increasing traffic-induced stresses. During train operations, ballast deteriorates due to progressive breakage and fouling caused by the infiltration of fine particles from the surface or mud-pumping from the underneath layers (e.g. sub-ballast, sub-grade), which decreases the load bearing capacity, impedes drainage and increases the deformation of ballasted tracks. Suitable ground improvement techniques involving geosynthetics and resilient rubber sheets are commonly employed to enhance the stability and longevity of rail tracks. This keynote paper focuses mainly on research projects undertaken at the University of Wollongong to improve track performance by emphasising the main research outcomes and their practical implications. Results from laboratory tests, computational modelling and field trials have shown that track behaviour can be significantly improved by the use of geosynthetics, energy-absorbing rubber mats, rubber crumbs and infilled-recycled tyres. Full-scale monitoring of instrumented track sections supported by rail industry (ARTC) has been performed, and the obtained field data for in situ stresses and deformations could verify the track performance, apart from validating the numerical simulations. The research outcomes provide promising approaches that can be incorporated into current track design practices to cater for high-speed freight trains carrying heavier loads