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- MarinEye - A tool for marine monitoringPublication . Martins, Alfredo; Dias, André; Silva, Eduardo; Ferreira, Hugo; Dias, Ireneu; Almeida, José Miguel; Torgo, Luis; Gonçalves, Marco; Guedes, Maurício; Dias, Nuno; Jorge, Pedro; Mucha, Ana Paula; Magalhães, Catarina; Carvalho, Maria de Fátima; Ribeiro, Hugo; Almeida, C. Marisa R.; Azevedo, Isabel; Ramos, Sandra; Borges, Teresa; Leandro, Sérgio Miguel; Maranhão, Paulo; Mouga, Teresa; Gamboa, Roberto; Lemos, Marco; Santos, Antonina dos; Silva, Alexandra; Frazão e Teixeira, Bárbara; Bartilotti, Cátia; Marques, Raquel; Cotrim, SóniaThis work presents an autonomous system for marine integrated physical-chemical and biological monitoring – the MarinEye system. It comprises a set of sensors providing diverse and relevant information for oceanic environment characterization and marine biology studies. It is constituted by a physicalchemical water properties sensor suite, a water filtration and sampling system for DNA collection, a plankton imaging system and biomass assessment acoustic system. The MarinEye system has onboard computational and logging capabilities allowing it either for autonomous operation or for integration in other marine observing systems (such as Observatories or robotic vehicles. It was designed in order to collect integrated multi-trophic monitoring data. The validation in operational environment on 3 marine observatories: RAIA, BerlengasWatch and Cascais on the coast of Portugal is also discussed.
- Limestone Processing Sludge: From Waste to Sustainable ResourcePublication . Guedes, Mafalda; Carrasqueira, Joana; Seixas, Tomás; Afonso, Clélia; Gil, Maria Manuel; Bernardino, Raul; Gamboa, Roberto; Bernardino, SusanaThe limestone quarrying and processing industry generates huge amounts of waste, with limestone sludge being one of the most prevalent and challenging by-products. This study aims to evaluate the potential of limestone sludge as a sustainable secondary raw material for the mechanochemical synthesis of bioceramics, specifically hydroxyapatite (HA), for high-added-value applications in bone tissue engineering. High-energy milling is innovatively used as the processing route: dry sludge (functioning as the calcium source), a phosphate source, and water were milled with the aim of producing calcium phosphates (in particular, hydroxyapatite) via mechanosynthesis. The industrial sludge was thoroughly analyzed for chemical composition, heavy metals, and mineral phases to ensure suitability for biomedical applications. The mixture of reagents was tailored to comply with Ca/P = 1.67 molar ratio. Milling was carried out at room temperature; the milling velocity was 600 rpm, and milling time ranged from 5 to 650 min. Characterization by XRD, Raman spectroscopy, and SEM confirmed the progressive transformation of calcite into hydroxyapatite through a metastable DCPD intermediate, following logarithmic reaction kinetics. The resulting powders are fine, homogeneous, and phase-pure, demonstrating that mechanosynthesis provides a low-cost and environmentally friendly pathway to convert limestone waste into functional bioceramic materials. This suggests that Moleanos sludge is a viable and sustainable source to produce tailored calcium phosphates and confirms mechanosynthesis as a cost-effective and reliable technology to activate the low-kinetics chemical reactions in the CaCO3-H3PO4–H2O system. This work highlights a novel circular economy approach for the valorization of industrial limestone sludge, turning a difficult waste stream into a high-value, sustainable resource.
- Recrystallization of silicon polygonal tubes using an electric closed molten zonePublication . Gamboa, Roberto; Brito, M.C.; Serra, J.M.; Alves, J. Maia; Vallêra, A.M.This article describes a process for generating and controlling a closed molten zone with an induced electrical current, and using it for silicon ribbon tube recrystallization. The silicon tube is the secondary loop of a transformer in which the current is generated by electrical induction. The Joule heat caused by the induced current generates a closed molten line along a cross section of the silicon tube; scanning this molten zone along the tube axis results in material recrystallization, with no contact with foreign materials. From the recrystallized silicon tube faces test solar cells were produced, revealing minority carrier diffusion lengths around 100 mm.