4,351 research outputs found

    Statistical modelling of railway track geometry degradation using hierarchical Bayesian models

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    Railway maintenance planners require a predictive model that can assess the railway track geometry degradation. The present paper uses a hierarchical Bayesian model as a tool to model the main two quality indicators related to railway track geometry degradation: the standard deviation of longitudinal level defects and the standard deviation of horizontal alignment defects. Hierarchical Bayesian Models (HBM) are flexible statistical models that allow specifying different spatially correlated components between consecutive track sections, namely for the deterioration rates and the initial qualities parameters. HBM are developed for both quality indicators, conducting an extensive comparison between candidate models and a sensitivity analysis on prior distributions. HBM is applied to provide an overall assessment of the degradation of railway track geometry, for the main Portuguese railway line Lisbon-Oporto

    The role of hydrophobicity in bacterial adhesion

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    In biological systems, hydrophobic interactions are usually considered to be the strongest of all long-range non-covalent interactions. Considering hydrophobicity as the energy of interaction, ΔGiwi, between two entities (i) immersed in water (w): then a positive value means that i is hydrophilic, and when ΔGiwi has a negative value, i is hydrophobic. In other words, an increase in ΔGiwi means a decrease in hydrophobicity. The above concept was used in the interpretation of various adhesion experiments: (I) adhesion of a denitrifying strain (Alcaligenes denitrificans) to polymeric surfaces; (II) adhesion of an anaerobic consortium to porous microcarriers; (IV) adhesion of Staphylococcus epidermidis to polymeric materials, used in medical indwelling devices. In all the mentioned studies a linear correlation was obtained between the degree of hydrophobicity of the supporting surfaces and the number of adhered cells

    Empatia vs e-Empatia

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    A educação é um elemento-chave para reduzir os riscos criados pela crise social no contexto de (pós)pandemia. Assim, a educação emocional e social, ao promover fatores como a empatia, é essencial para lidar com as graves consequências da pandemia e dos seus efeitos nas desigualdades sociais.info:eu-repo/semantics/acceptedVersio

    A comparison of the CARATKids and CARAT10 questionnaires for the evaluation of control of asthma and allergic rhinitis in adolescents

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    [Excerpt] The Control of Allergic Rhinitis and Asthma Test (CARAT) was introduced to assess control of allergic rhinitis and asthma (ARA) simultaneously. It is the first tool to implement ARIA guidelines in clinical practice [1-5].CARAT10 was developed for adults [5], and CARATKids was designed for children aged 6 to 12 years [6]. There is no validated questionnaire to assess control of ARA in patients between the ages of 12 to 17 years.Financial support for this work was provided by FEDER funds through the Operational Programme Competitiveness Factors—COMPETE and National Funds through FCT— Foundation for Science and Technology under project POCI-01-0145-FEDER--007038 and project NORTE-01-0145-FEDER-000013, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF)

    Norbornene-chitosan spray-dried microspheres for peptide conjugation using thiol-ene “photoclick” chemistry

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    This work was financed by Portuguese funds through FCT/MCTES (Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Inovação) in the framework of the projects 2022.06048.PTDC (i3S), UIDB/50006/2020 (LAQV-REQUIMTE), LA/P/0045/2020 (ALiCE) and UIDB/00511/2020 (LEPABE). P.A. (SFRH/BD/145471/2019) and D.F. (SFRH/ BD/146890/2019) doctoral grants, were financially supported by national (FCT/Norte 2020 Framework) and European Union (ESF – European Social Fund) funds. B.E. acknowledges FCT for the contract based on the “Lei do Emprego Científico” (DL 57/2016). Maria Cristina L. Martins also acknowledges FCT (LA/P/0070/2020), project Bio2Skin Advanced (2021-24):NORTE-01-0247-FEDER-047225; and MOBILIsE Project, which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 951723.The action of bioactive peptides, such as antimicrobial peptides (AMP), in the human body is often compromised by limited residence time and stability in the target site. Bioconjugation of peptides to biomaterial surfaces is one of the strategies that may overcome these limitations. Herein, norbornene-chitosan (NorChit) microspheres were engineered to react with thiolated peptides by thiolene “photoclick” chemistry. NorChit microspheres were produced by spray drying and crosslinked with dithiothreitol (DTT) to prevent their solubilization. Microspheres with a diameter of 5 ± 2 µm showed round and smooth morphology with pockets over the surface that could be related with hydrophobic interactions between internal norbornene groups. Thiol-ene bioconjugation carried out using a fluorescent model peptide, showed a yield of 45%, whereas using the peptide but without UV exposure indicated a maximum of peptide adsorption of 30%. Altogether, NorChit microspheres show the potential for carrying bioactive peptides, which may open avenues for AMP activity onto harsh environments in the bod

    Staphylococcus epidermidis adhesion on modified urea/urethane elastomers

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    Block urea/urethane co-polymer films present elastomeric properties with the possible tuning of their surface properties within a wide range and are therefore considered relevant surfaces for possible medical applications. In particular, thin free standing films of urea/urethane elastomers with two soft segments, polypropylene oxide and more hydrophobic polybutadiene, develop multistable states with surface topography features with remarkable regularity. Moreover, complex surface structures may be obtained by UV radiation treatment followed by suitable mechanical action and also by extraction of the elastomer with a suitable solvent. In the present work, different modified elastomer samples were assayed for Staphylococcus epidermidis adhesion during 2 h and the extent of bacterial adhesion was evaluated by automatic cell enumeration. Bacterial adhesion assays demonstrate that the typical trend relating the increase in the number of adhered bacteria with the increase of the surface roughness does not hold for all materials. Results may be interpreted taking into account both the surface topography and the different types ofmicro-phase segregation of hydrophobic and hydrophilic parts of the elastomer.Fundação para a Ciência e a Tecnologia (FCT)

    Geologia estrutural e geotecnia do maciço granítico do Alto da Cabeça Santa (NW de Portugal): implicações para a gestão do georrecurso da pedreira da Mimosa

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    This work presents the results of the structural geology, geomorphology and geotechnics studies of block delimitation of a granitic rock mass. For this characterisation, the scanline sampling technique of discontinuities has been applied to the study of free rock mass faces from Mimosa granitic quarry (Alto da Cabeça Santa, Penafiel; NW Portugal). For that purpose, the surrounding area of the open quarry as well as selected granitic outcrops were studied using the following tools: surface geological/geomorphological mapping, structural geology and geotechnics/geomechanics techniques. So, a morphotectonic analysis of topographic map and geological survey has then been carried out. In addition, the evaluation methods of field data for discontinuities sets and the statistical characterisation of their orientation, spacing and extension are also presented. The results achieved at different scales are compared in order to detect the presence of a multiscale fracture network pattern. The use of these techniques for understanding the rock mass block delimitation may contribute to improve the sustainable management of the georesources from Mimosa granitic quarry

    Modulation of the Redox Potential and Electron/Proton Transfer Mechanisms in the Outer Membrane Cytochrome OmcF From Geobacter sulfurreducens

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    PD/00193/2012 UID/FIS/00068/2019 PTDC/BBBBQB/3554/2014 PTDC/BIA-BQM/31981/2017 PD/BD/114445/2016 UID/Multi/04378/2019 ROTEIRO/0031/2013 -PINFRA/22161/2016The monoheme outer membrane cytochrome F (OmcF) from Geobacter sulfurreducens plays an important role in Fe(III) reduction and electric current production. The electrochemical characterization of this cytochrome has shown that its redox potential is modulated by the solution pH (redox-Bohr effect) endowing the protein with the necessary properties to couple electron and proton transfer in the physiological range. The analysis of the OmcF structures in the reduced and oxidized states showed that with the exception of the side chain of histidine 47 (His47), all other residues with protonatable side chains are distant from the heme iron and, therefore, are unlikely to affect the redox potential of the protein. The protonatable site at the imidazole ring of His47 is in the close proximity to the heme and, therefore, this residue was suggested as the redox-Bohr center. In the present work, we tested this hypothesis by replacing the His47 with non-protonatable residues (isoleucine – OmcFH47I and phenylalanine – OmcFH47F). The structure of the mutant OmcFH47I was determined by X-ray crystallography to 1.13 Å resolution and showed only minimal changes at the site of the mutation. Both mutants were 15N-labeled and their overall folding was confirmed to be the same as the wild-type by NMR spectroscopy. The pH dependence of the redox potential of the mutants was measured by cyclic voltammetry. Compared to the wild-type protein, the magnitude of the redox-Bohr effect in the mutants was smaller, but not fully abolished, confirming the role of His47 on the pH modulation of OmcF’s redox potential. However, the pH effect on the heme substituents’ NMR chemical shifts suggested that the heme propionate P13 also contributes to the overall redox-Bohr effect in OmcF. In physiological terms, the contribution of two independent acid–base centers to the observed redox-Bohr effect confers OmcF a higher versatility to environmental changes by coupling electron/proton transfer within a wider pH range.publishersversionpublishe
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