Triplite-zwieselite, fluorapatite and isokite evolution products from the Sítio do Castelo mine at Folgosinho, Guarda

A mina Sítio do Castelo explorou em meados dos anos 70 uma importante massa quartzosa na proximidade da povoação de Folgosinho. Os trabalhos a céu aberto bem como as diversas galerias expuseram corpos fosfáticos intensamente oxidados, onde foi possível observar uma grande variedade de fosfatos secundários. O reconhecimento de vários corpos fosfáticos permitiu definir dois tipos de ocorrências: 1- Triplite – zwieselite como único fosfato primário; 2- Triplite - zwieselite em associação com fluorapatite e isokite. A alteração destes fosfatos em combinação com sulfuretos (esfalerite, arsenopirite e calcopirite) resulta em diferentes associações paragenéticas, as quais servem de argumento para a proposta das linhagens evolutivas que lhes correspondem.In the mid 70's, the ‘Sitio do Castelo’ mine has exploited an important lens of quartz near the village of Folgosinho. The open pit, as well as the several galleries, has exposed intensely oxidized phosphatic bodies, where it was possible to observe a wide variety of secondary phosphates. The recognition of several phosphatic bodies allowed definig two types of occurences: 1- Triplite - zwieselite phosphate as the sole primary phosphate; 2- Triplite - Zwieselite in association with fluorapatite and isokite. The weathering of these phosphates in combination with several sulphide minerals (sphalerite, arsenopyrite and chalcopyrite) resulted in different paragenetic associations, which serve as argument for the proposed evolutionary paths.Fundação para a Ciência e a Tecnologia com fundos nacionai

Ionic size effects on the Poisson-Boltzmann theory

In this paper, we develop a simple theory to study the effects of ionic size on ionic distributions around a charged spherical particle. We include a correction to the regular Poisson-Boltzmann equation in order to take into account the size of ions in a mean-field regime. The results are compared with Monte Carlo simulations and a density functional theory based on the fundamental measure approach and a second-order bulk expansion which accounts for electrostatic correlations. The agreement is very good even for multivalent ions. Our results show that the theory can be applied with very good accuracy in the description of ions with highly effective ionic radii and low concentration, interacting with a colloid or a nanoparticle in an electrolyte solution

An application of Preference-Inspired Co-Evolutionary Algorithm to sectorization

Sectorization problems have significant challenges arising from the many objectives that must be optimised simultaneously. Several methods exist to deal with these many-objective optimisation problems, but each has its limitations. This paper analyses an application of Preference Inspired Co-Evolutionary Algorithms, with goal vectors (PICEA-g) to sectorization problems. The method is tested on instances of different size difficulty levels and various configurations for mutation rate and population number. The main purpose is to find the best configuration for PICEA-g to solve sectorization problems. Performancemetrics are used to evaluate these configurations regarding the solutions’ spread, convergence, and diversity in the solution space. Several test trials showed that big and medium-sized instances perform better with low mutation rates and large population sizes. The opposite is valid for the small size instances.info:eu-repo/semantics/acceptedVersio

Brass smelting dust as a source of ZnO in the production of targets used in magnetron sputtering thin film deposition

The feasibility of using a zinc oxide rich waste (ZnO>95%), dust originated in the brass smelting industrial process, as a raw material to produce targets to be used in radiofrequency magnetron sputtering (RFMS) deposition of ZnO thin films was investigated. The ZnO waste was characterized in terms of chemical and mineralogical compositions and particle size distribution. The targets were prepared by uniaxial pressing of the ZnO waste followed by sintering in air at a temperature in the range 900-1200 ºC. The density of sintered targets increased with sintering temperature, and zincite (ZnO) was the predominant crystalline phase identified by X-ray diffraction (XRD). Scanning electron microscopy (SEM) revealed zincite grains, with an average size ~2 m and a nonhomogeneous microstructure due to the presence of dense aggregates. Preliminary MS thin film deposition tests on a glass substrate produced transparent nanostructured ZnO thin films with a homogeneous microstructure. Research work is underway to process ZnO waste-based targets with an improved microstructure in order to obtain RFMS deposited ZnO thin films with optimized final electrical and optical properties

Características físicas e químicas de um neossolo, regolítico, eutrófico do Agreste pernambucano.

Procedeu-se a descrição, caracterização e interpretação de um Neossolo Regolítico Eutrófico. Esta caracterização foi realizada através do estudo do perfil do solo no campo, que incluiu a identificação dos horizontes e a determinação das características do solo. O trabalho foi feita de acordo com as normas do Sistema Brasileiro de Classificação de Solos. Representa ambiente que tem como limitações a susceptibilidade a erosão, dificuldade de mecanização e a pequena profundidade. Por se tratar de um solo raso e de textura arenosa constitui ambiente com pouca sustentabilidade para as plantas sobreviverem, nos períodos cíclicos de estiagem. Apresenta boa fertilidade natural, devido a presença de minerais primários facilmente intemperizáveis e ricos em nutrientes, principalmente em cálcio, magnésio e potássio. Em geral, são solos utilizados para pecuária extensiva e agricultura familiar ( mandioca, feijão comum e caupi, caju, tomate e capim elefante)

COVID-19 in a Pediatric Cohort—Retrospective Review of Chest Computer Tomography Findings

Background: Radiological features of the novel 2019 coronavirus disease (COVID-19) have been mainly described in adults. Available literature states that imaging findings in children are similar but less pronounced. The aim of this study is to describe and illustrate the chest computer tomography (CT) features of pediatric COVID-19. Results: This retrospective study was based on the review of all the chest CTs performed in pediatric patients with confirmed COVID-19 disease between March 8th and May 26th 2020 (n = 24). The presence of comorbidities and coinfection was assessed, as well as timing of CT examination in relation to the onset of symptoms. CT findings were categorized as typical, indeterminate, atypical, and negative for COVID-19 according to International Expert Consensus Statement on Chest Imaging in Pediatric COVID-19 Patient Management. This study found that CT findings were abnormal in 17 (71%) patients, with 5 (21%), 9 (38%), and 3 (13%) patients considered to have typical, indeterminate, and atypical findings, respectively. The most common CT patterns were multiple ground-glass opacities (58%), followed by consolidations (50%). Six patients showed predominantly peripheral distribution of parenchymal abnormalities. A halo sign was identified in 3 patients and a perilobular pattern was identified in one of the cases with typical findings. Conclusions: Chest CT findings in children infected with SARS-CoV-2 can be subtle or absent. Besides recognizing typical findings, radiologists should be able to identify features that favor different or concomitant diagnosis.info:eu-repo/semantics/publishedVersio

A resectorization of fire brigades in the north of Portugal

Sectorization consists of grouping the basic units of a large territory to deal with a complex problem involving different criteria. Resectorization rearranges a current sectorization avoiding substantial changes, given a set of conditions. The paper considers the case of the distribution of geographic areas of fire brigades in the north of Portugal so that they can protect and rescue the population surrounding the fire stations. Starting from a current sectorization, assuming the geographic and population characteristics of the areas and the fire brigades’ response capacity, we provide an optimized resectorization considering two objectives: to reduce the rescue time by maximizing the compactness criterion, and to avoid overload situations by maximizing the equilibrium criterion. The solution method is based on the Non-dominated Sorting Genetic Algorithm (NSGA-II). Finally, computational results are presented and discussed.info:eu-repo/semantics/acceptedVersio

Análise econômica e coeficientes técnicos para a cultura da melancia irrigada na Baixada Maranhense.

O conhecimento do custo de produção de uma cultura é de fundamental importância para a análise econômica de uma propriedade agrícola. Uma propriedade só é sustentável economicamente se o custo de produção, considerando ao menos os custos variáveis, for inferior à receita bruta desta, mantendo-se assim a sustentabilidade da propriedade agrícola