A voltametria cíclica e de varrimento linear unidirecional: suas potencialidades na caraterização de processos de corrosão

Artigo licenciado sob uma Licença Creative Commons: https://creativecommons.org/licenses/by-nc/4.0/deed.pt"O artigo apresenta as técnicas da voltametria cíclica e da voltametria de varrimento linear unidirecional, que são métodos eletroquímicos extremamente úteis e versáteis no estudo do comportamento de um metal ou liga, face a ambientes mais ou menos agressivos. As potencialidades das técnicas são realçadas, assim como as vantagens introduzidas pela instrumentação digital. Trata-se de um artigo de divulgação, tendo por objetivo ser acessível a engenheiros, técnicos e outros, a trabalhar na área da corrosão. Para exemplificar o tipo de informação que pode ser obtida são apresentados resultados de vários estudos realizados pelos autores.

A review

Funding Information: This work was funded by the R&D Project CAREBIO2-Comparative assessment of antimicrobial resistance in environmental biofilms through proteomics-towards innovative theranostic biomarkers, with reference NORTE-01-0145-FEDER-030101, financed by the European Regional Development Fund (ERDF) through the Northern Regional Operational Program (NORTE 2020) and the Foundation for Science and Technology (FCT). Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Staphylococcus aureus is an opportunist pathogen that is responsible for numerous types of infections. S. aureus is known for its ability to easily acquire antibiotic resistance determinants. Methicillin-resistant S. aureus (MRSA) is a leading cause of infections both in humans and animals and is usually associated with a multidrug-resistant profile. MRSA dissemination is increasing due to its capability of establishing new reservoirs and has been found in humans, animals and the environment. Despite the fact that the information on the incidence of MRSA in the environment and, in particular, in wild animals, is scarce, some studies have reported the presence of these strains among wildlife with no direct contact with antibiotics. This shows a possible transmission between species and, consequently, a public health concern. The aim of this review is to better understand the distribution, prevalence and molecular lineages of MRSA in European free-living animals.publishersversionpublishe

Low load Pt catalyst with surface functionalised carbon supports for PEM fuel cells: half and full cell asssessments

ABSTRACT: Current US DOE 2020 targets for electrocatalysts aim for a total platinum group metals (PGM) loading of 0.125 mgcm-2 on membrane-electrode assemblies. The catalysts are expected to endure an elevated number of load cycles in order to comply with the expected 5000 h stack lifetime. At the stated PGM low loading attributes of performance, power and durability, as well as costs, are simultaneously required. The present paper deals with performance assessment of new catalyst using Pt nanoparticles and a surface functionalized carbon support. Due to its relevance to fuel cell operation, the stability and durability were assessed in half cell mode, through the application of demanding aging cycling protocols (30000 cycles). Full fuel cell assessments were also conducted entailing power density curves and cell electrochemical impedance. Results denote significant improvements in cell performance as well as in catalyst stability, regarding a commercial catalyst tested in the same conditions, at Pt loadings of 0.1 mgcm-2.N/

Galvanic corrosion of two non noble dental alloys

Artigo licenciado sob uma Licença Creative Commons: https://creativecommons.org/licenses/by/4.0/"This study aims to evaluate the corrosion resistance of two nonnoble dental alloys, namely, the Wiron®88 (Ni–Cr–Mo) and the Remanium 2000+ (Co–Cr–Mo–W). A noble alloy, the V-Gnathos® Plus (AuPt) previously studied was also considered for the purpose of comparison. The study was conducted in artificial saliva, pH 7.1, at 37 °C, by cyclic and linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The Rp value of the alloy of high contents of Ni, the Wiron®88, was 26.2±0.2 kΩ cm2 and of the one with high contents of Co, the Remanium 2000+, was 22.5±0.6 kΩ cm2. Data from linear polarization resistance and electrochemical impedance spectroscopy lead to the same order for the resistance against corrosion. The order from the less to the more reactive alloy is: Wiron®88 → Remanium 2000+. The galvanic cell obtained by coupling the two nonnoble alloys presents very low cell potential (a few mV, -18 mV), while the galvanic cell between one noble alloy (the V-Gnathos® Plus) and the Wiron®88 showed a higher cell potential (-104 mV). Both galvanic couples, under short circuit, have lead to the release of cations, namely, Co2+, in the case of the Wiron®88|Remanium 2000+ and Ni2+ for the Wiron®88|V-Gnathos® Plus, galvanic couples, respectively, with the ionic concentrations reaching values of 12.15 and 7.30 μg L-1 (7.30 ppb), respectively. SEM micrographs obtained after 25 days immersion in artificial saliva, at 37 °C, showed the formation of well-defined pits on the surface of the two non-noble alloys.

The impact of artificial intelligence on commercial management

The essence of this research is to shed light on use and importance of artificial intelligence (AI) in commercial activity. As such, the objective of the present study is to understand the impact of AI tools on the development of business functions and if they can be affirmed as a means of help or as a substitute for these functions. In-depth interviews were conducted with 15 commercial managers from technological SMEs. The results indicate that all the participants use AI systems frequently, that these tools assist in developing of their functions, allowing having more time and better preparing to solve the commercial problems. The findings also indicate that the tools used by commercials are still somewhat limited, and companies should focus on their training and development in AI, as well as the training of their commercials. Furthermore, the results show that firms intend to use the data collection and the analytical tool that enable real-time response and customization according to customer needs.info:eu-repo/semantics/publishedVersio

the next frontier in medicine

PM003/2016publishersversionpublishe

DTT protein equalization and Tryptophan protein quantification as a powerful tool in analytical proteomics

PM003/ 2016). This work received support from Funda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia and Minist\u00E9rio da Ci\u00EAncia, Tecnologia e Ensino Superior (FCT/MCTES) through the projects LA/P/0008/2020 DOI 10.54499/LA/P/0008/2020, UIDP/50006/2020 DOI 10.54499/UIDP/50006/2020 and UIDB/50006/2020 DOI 10.54499/UIDB/50006/2020. H.M.S. acknowledges the Associate Laboratory for Green Chemistry-LAQV (LA/P/0008/2020) DOI 10.54499/LA/P/0008/2020 funded by FCT/ MCTES for his research contract. L.B.C. is supported by the FCT/ MCTES PhD grant 2019 (SFRH/BD/144222/2019). Publisher Copyright: © 2024, Proteomass Scientific Society. All rights reserved.Assessing total protein levels in biological samples is a common procedure in biochemistry and molecular biology. In this study, we compare tryptophan fluorescence (WF) with Bradford and BCA assays to determine total protein in serum samples. Our results indicate that tryptophan fluorescence spectrometry is an efficient, sensitive, and straightforward technique for quantifying proteins in serum. We observed minimal variation between the three methods: BCA de one with the lowers LOD and LOQ. The tryptophan method offers the possibility of reusing the intact sample that does not need colourimetric reagents for quantification. Consequently, free tryptophan serves as a reliable universal standard. This assay can be performed using a conventional fluorescence spectrometer with cuvettes or in a 96-well plate format with a plate reader. The method was successfully used as proof of concept, using serum from patients diagnosed with myeloma and serum from healthy donors.publishersversionpublishe

2,2'-(2,2'-oxybis(ethane-2,1-diyl)bis(oxy))bis(N-(2,2'-bithiophen-5-ylmethylene)aniline)

We would like to thank Xunta de Galiza (Spain) for project 09CSA043383PR and the University of Vigo, Vicou for projects INOU UVIGO/VICOU/K914-122P64702/2009 and UVIGO/VICOU/K912-122P64702/2009. Thanks to the FCT-MCTES/FEDER (Portugal) through national projects POCI/QUI/55519/2004 and PDTC/QUI/66250/2006. B. P thanks FCT/Portugal for the PhD Grant SFRH/BD/27786/2006. C.L. and J.L. thank Xunta de Galicia for the Isidro Parga Pondal Research Program.A new flexible fluorescent compound L derived from 1,5-bis(2-aminophenoxy)-3-oxapentane (A) has been synthesized by classical Schiff-base reaction between (A) and 2,2 ́-bithiophene carbaldehyde (B). The same synthesis was reproduced by a green methodology using an ultrasonication reaction in a classical sonication bath. The structure of the new compound was confirmed by elemental analysis, IR, 1H-NMR, MALDI-TOF-MS and EI-MS-spectra, UV-vis and fluorescence emission spectroscopy.publishersversionpublishe

Light, medium-weight or heavy? The nature of the first supermassive black hole seeds

Observations of hyper-luminous quasars at $z>6$ reveal the rapid growth of supermassive black holes (SMBHs $>10^9 \rm M_{\odot}$) whose origin is still difficult to explain. Their progenitors may have formed as remnants of massive, metal free stars (light seeds), via stellar collisions (medium-weight seeds) and/or massive gas clouds direct collapse (heavy seeds). In this work we investigate for the first time the relative role of these three seed populations in the formation of $z>6$ SMBHs within an Eddington-limited gas accretion scenario. To this aim, we implement in our semi-analytical data-constrained model a statistical description of the spatial fluctuations of Lyman-Werner (LW) photo-dissociating radiation and of metal/dust enrichment. This allows us to set the physical conditions for BH seeds formation, exploring their relative birth rate in a highly biased region of the Universe at $z>6$. We find that the inclusion of medium-weight seeds does not qualitatively change the growth history of the first SMBHs: although less massive seeds ($<10^3 \rm M_\odot$) form at a higher rate, the mass growth of a $\sim 10^9 \rm M_\odot$ SMBH at $z<15$ is driven by efficient gas accretion (at a sub-Eddington rate) onto its heavy progenitors ($10^5 \rm M_\odot$). This conclusion holds independently of the critical level of LW radiation and even when medium-weight seeds are allowed to form in higher metallicity galaxies, via the so-called super-competitive accretion scenario. Our study suggests that the genealogy of $z \sim 6$ SMBHs is characterized by a rich variety of BH progenitors, which represent only a small fraction ($< 10 - 20\%$) of all the BHs that seed galaxies at $z > 15$.Comment: (21 pages, 18 figures, 2 tables. Accepted for publication in MNRAS

Identification of genomic loci associated with genotypic and phenotypic variation among Pseudomonas aeruginosa clinical isolates from pneumonia

In this work, a genotype-phenotype survey of a highly diversified Pseudomonas aeruginosa collection was conducted, aiming to detail pathogen-associated scenarios that clinicians face nowadays. Genetic relation based on RAPD-PCR of 705 isolates, retrieved from 424 patients and several clinical contexts, reported an almost isolate-specific molecular-pattern. Pneumonia-associated isolates HB13 and HB15, clustered in the same RAPD-PCR group, were selected to evaluate the genomic background underlying their contrasting antibiotic resistance and virulence. The HB13 genome harbors antibiotic-inactivating enzymes-coding genes (e.g. aac(3)-Ia, arr, blaVIM-2) and single-nucleotide variations (SNVs) in antibiotic targets, likely accounting for its pan-resistance, whereas HB15 susceptibility correlated to predicted dysfunctional alleles. Isolate HB13 showed the unprecedented rhl-cluster absence and variations in other pathogen competitiveness contributors. Conversely, HB15 genome comprises exoenzyme-coding genes and SNVs linked to increased virulence. Secretome analysis identified signatures features with unknown function as potential novel pathogenic (e.g. a MATE-protein in HB13, a protease in HB15) and antibiotic resistance (a HlyD-like secretion protein in HB13) determinants. Detection of active prophages, proteases (including protease IV and alkaline metalloproteinase), a porin and a peptidase in HB15 highlights the secreted arsenal likely essential for its virulent behavior. The presented phenotype-genome association will contribute to the current knowledge on Pseudomonas aeruginosa pathogenomics.This work was supported by the strategic programme UID/BIA/0050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through FCT I.P., by ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and through a PhD grant (SFRH/BD/98558/2013) attributed to C.S.M. The facility for Biological Mass Spectrometry Isabel Moura was funded by Proteomass Scientific Society. H.M.S. is funded by the FCT 2015 Investigator Program (IF/00007/2015)