Polarization Charge Distribution in Gapped Graphene

We study the distribution of vacuum polarization charge induced by a Coulomb impurity in massive graphene. By analytically computing the polarization function, we show that the charge density is distributed in space in a non-trivial fashion, and on a characteristic length-scale set by the effective Compton wavelength. The density crosses over from a logarithmic behavior below this scale, to a power law variation above it. Our results in the continuum limit are confirmed by explicit diagonalization of the corresponding tight-binding model on a finite-size lattice. Electron-electron interaction effects are also discussed.Comment: 6 pages, 4 figures; expanded versio

Multiscale Fractal Descriptors Applied to Nanoscale Images

This work proposes the application of fractal descriptors to the analysis of nanoscale materials under different experimental conditions. We obtain descriptors for images from the sample applying a multiscale transform to the calculation of fractal dimension of a surface map of such image. Particularly, we have used the}Bouligand-Minkowski fractal dimension. We applied these descriptors to discriminate between two titanium oxide films prepared under different experimental conditions. Results demonstrate the discrimination power of proposed descriptors in such kind of application

Characterization of nanostructured material images using fractal descriptors

This work presents a methodology to the morphology analysis and characterization of nanostructured material images acquired from FEG-SEM (Field Emission Gun-Scanning Electron Microscopy) technique. The metrics were extracted from the image texture (mathematical surface) by the volumetric fractal descriptors, a methodology based on the Bouligand-Minkowski fractal dimension, which considers the properties of the Minkowski dilation of the surface points. An experiment with galvanostatic anodic titanium oxide samples prepared in oxalyc acid solution using different conditions of applied current, oxalyc acid concentration and solution temperature was performed. The results demonstrate that the approach is capable of characterizing complex morphology characteristics such as those present in the anodic titanium oxide.Comment: 8 pages, 5 figures, accepted for publication Physica

A Benchmark dataset for predictive maintenance

The paper describes the MetroPT data set, an outcome of a eXplainable Predictive Maintenance (XPM) project with an urban metro public transportation service in Porto, Portugal. The data was collected in 2022 that aimed to evaluate machine learning methods for online anomaly detection and failure prediction. By capturing several analogic sensor signals (pressure, temperature, current consumption), digital signals (control signals, discrete signals), and GPS information (latitude, longitude, and speed), we provide a dataset that can be easily used to evaluate online machine learning methods. This dataset contains some interesting characteristics and can be a good benchmark for predictive maintenance models

Echinoderms of Cabeço da Ladeira : a case of geological heritage

O presente trabalho pretende descrever o processo de intervenção no geossítio Equinodermes do Cabeço da Ladeira, concelho de Porto de Mós. Este local foi assim classificado por conter fósseis de equinodermes detentores de importância científica significativa, merecendo especial atenção e medidas de preservação. Expõem-se os passos tomados desde a sua identificação ate às ações mais recentes, que envolveram a inventariação dos exemplares fósseis. O futuro do local é também abordado, pretendendo-se que passe pela requalificação do local como espaço de visitação musealizado.This paper aims to describe the process of intervention in the geosite “Equinodermes do Cabeço da Ladeira”, municipality of Porto de Mós. Exceptionally preserved fossil echinoderms were found in this locality, bearing scientific importance and deserving special attention and conservation measures. Here are described the steps taken from identification of the site, until the most recent actions that ensure the preservation of that fossil locality. The future ideas for that area are also explained, aiming to transform what was once a quarry to an open-air museum.LNEG, ICN

Própolis: efeito na fragilidade osmótica da membrana eritrocitária

Própolis é uma substância resinosa colhida das plantas, pelas abelhas. A composição do própolis depende da vegetação envolvente, da estação do ano, e da área da qual provém. Este produto da colmeia contém normalmente, uma grande variedade de compostos químicos, tais como polifenóis (flavonóides, ácidos fenólicos e ésters), esteróides e aminoácidos. A esferocitose hereditária (EH) é um tipo de anemia de transmissão hereditária que resulta da presença de eritrócitos microcíticos e hipercromicas, esféricos e sem palidez central. Clinicamente, os indivíduos apresentam normalmente desde condições assintomáticas até anemias hemolíticas graves. Os objectivos deste estudo foram avaliar o efeito de dois extractos de própolis, oriundos de diferentes regiões (Bornes – Trás-os-Montes; Fundão – Beira Interior), na fragilidade osmótica da membrana eritrocitária em pacientes com Esferocitose Hereditária. Para avaliar o efeito do própolis este foi extraído com DMSO (Dimetilsulfóxido), e posteriormente testado no sangue de dois indivíduos, um com esferocitose hereditária e outro sem esta patologia. O sangue utilizado foi obtido por punção venosa com EDTA sódico. No indivíduo portador da doença procedeu-se aos testes de fragilidade osmótica, tendo-se verificado que ambos os própolis demonstraram efeito sob a membrana do eritrócito, no entanto o efeito do própolis oriundo de Bornes - Trás-os-Montes foi mais acentuado comparativamente com o do Fundão – Beira Interior. Estes resultados abrem portas a investigações futuras, no sentido de elucidar os mecanismos pelos quais o própolis altera a fragilidade da membrana eritrocitária

Equinodermes do Cabeço da Ladeira : um caso de preservação do património geológico

O presente trabalho pretende descrever o processo de intervenção no geossítio Equinodermes do Cabeço da Ladeira, concelho de Porto de Mós. Este local foi assim classificado por conter fósseis de equinodermes detentores de importância científica significativa, merecendo especial atenção e medidas de preservação. Expõem-se os passos tomados desde a sua identificação até às ações mais recentes, que envolveram a inventariação dos exemplares fósseis. O futuro do local é também abordado, pretendendo-se que passe pela requalificação do local como espaço de visitação musealizado

Additive manufacturing of embedded thermocouples in WC-Co cutting tools for cutting temperature measurement

A publicar em PowderMet2023, 18 - 21 jun. 2023, Caesars Palace, Las Vegas, USADuring machining processes, a large amount of heat is generated due to deformation of the material and friction of the chip along the surface of the tool, especially in the cutting zone. This high temperature strongly influences tribological phenomena and adhesion, tool wear, tool life, workpiece surface integrity and quality, chip formation mechanisms and contribute to the thermal deformation of the cutting tool, leading to high operating costs and reduction of the end product quality. In this sense, being able to assess the cutting temperature in real time, at various points of the cutting tool during machining processes, is of utmost importance to effectively optimize cutting parameters and the cutting fluid flow adequately, for minimizing heat generation, temperature and consequently wear, allowing to increase tool life. This work proposes the fabrication of embedded additively manufactured type K and type N thermocouples by laser powder bed fusion for real time cutting temperature measurement. Processing parameters optimization was performed to obtain a dense and continuous thermocouple with no significant defects and the additively manufactured thermocouples were tested in comparison to a conventional thermocouple. The obtained results show that this approach is effective to produce embedded thermocouples in WC-Co cutting tools capable of measuring cutting temperature, which will allow a real time optimization of the cutting parameters, namely cutting speed, feed and depth of cut, during in-service time, thus enhancing tool performance and life.This work was supported by FCT (Fundação para a Ciência e a Tecnologia) through the grant 2020.07155.BD and by the project POCI-01-0145-FEDER-030353 (SMARTCUT) and PTDC/EMEEME/1442/2020 (Add2MechBio). Additionally, this work was supported by FCT national funds, under the national support to R&D units grant, through the reference projects UIDB/04436/2020 and UIDP/04436/2020. Finally, this work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MCTES (PIDDAC)