2,705 research outputs found
Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphite
ABSTRACT: The hydrometallurgical extraction of metals from spent lithium-ion batteries (LIBs) was investigated. LIBs were first dismantled and a fraction rich in the active material was obtained by physical separation, containing 95% of the initial electrode, 2% of the initial steel and 22% of plastic materials. Several reducers were tested to improve metals dissolution in the leaching step using sulphuric acid. Sodium metabisulphite led to the best results and was studied in more detail. The best concentration of Na2S2O5 was 0.1 M. The metals dissolution increased with acid concentration, however, concentrations higher than 1.25 M are unnecessary. Best results were reached using a stirring speed of 400 min(-1). The metals leaching efficiency from the active material (Li, Mn, Ni, Co) increased with the temperature and was above 80% for temperatures higher than 60 degrees C. The dissolution of metals also rose with the increase in the liquid/solid ratio (LAS), however, extractions above 85% can be reached at LAS as lower as 4.5 L/kg, which is favourable for further purification and recovery operations. About 90% of metals extraction can be achieved after only 0.5 h of leaching. Sodium metabisulphite can be an alternative reducer to increase the leaching of Li, Mn, Co, and Ni from spent LIBs.info:eu-repo/semantics/publishedVersio
Recovery of lithium carbonate by acid digestion and hydrometallurgical processing from mechanically activated lepidolite
ABSTRACT: Lithium extraction from hard-rock ores has regained importance due to the increased demand for this metal to supply the growing battery market. Therefore, several studies have been focused on the lithium extraction from ores, however, leaching and purification steps are sparsely studied. Thus, the objective of this study was to evaluate the main factors affecting the water leaching step and the subsequent purification operations for lithium recovery from a lepidolite concentrate, which was processed by mechanical activation and sulphuric acid digestion. In the leaching step, among the variables studied, only one, the leaching temperature, showed a significant effect on the lithium extraction, taking into account the range of values tested. Thus, the recommended operating value for the leaching time and the L/S ratio is the minimum, while for the leaching temperature is 50°C. After optimizing the leaching operation, the purification of the leachate, by neutralization, was thoroughly performed by efficient removal of impurities (Fe, Al, Mn and Ca), allowing to obtain lithium carbonate as final product, as well as other relevant by-products, such as rubidium and potassium alums.info:eu-repo/semantics/publishedVersio
Optimization of metals extraction from spent lithium-ion batteries by sulphuric acid and sodium metabisulphite through a techno-economic evaluation
ABSTRACT: The main factors that affect the extraction of metals from spent lithium-ion batteries by acid leaching using H2SO4, and sodium metabisulphite, were evaluated and optimized through a set of experiments, framed by a techno-economic approach. The maximum value of the profit response was obtained with the highest possible values of acid concentration (2.5 M) and time (2 h), a liquid/solid ratio of 5 L/kg, and the lowest possible value of temperature (40 degrees C). After leaching, the electrodes active material contained in the metals decreased, while it was still significant in the graphite, as observed by scanning electron microscopy-energy dispersive spectrometry and x-ray powder diffraction. Even though the performed economic evaluation was a summarized outline it can be considered suitable to compare different leaching conditions and to determine the possible best combinations of factors that can optimize the profit response.info:eu-repo/semantics/publishedVersio
Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite
ABSTRACT: The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.info:eu-repo/semantics/publishedVersio
Black-bounce solution in -essence theories
In the present work, we construct black-bounce configurations in the context
of -essence theory. The solutions have a regular metric function at the
origin. The area metric function is linked to the black-bounce area initially
considered by Simpson-Visser, . Subsequently, the expressions
for the scalar field and scalar potential corresponding to the found solutions
are determined, exhibiting phantom behavior everywhere due to violation of Null
Energy Condition . The Kretschmann scalar is regular throughout
spacetime, and the geodesics are complete. The energy conditions are analyzed,
verifying that the null and dominant energy conditions
are violated inside and outside the event horizon. Finally, the
extrinsic curvature method was applied to determine the sign of the mass on the
junction surface.Comment: 13 pages, 15 figure
Robotics as a tool to increase the motivation levels in problematic students
The study described in this work was done by
students of the Training and Education Courses (CEFs) in Informatics Operators of EB 2,3 Gonçalo Sampaio in Póvoa de Lanhoso during the academic year 2008/09. The study was conducted with two classes, with a total of 23 students. These students are aged between 15 and 18 years and the majority are males with only 4 girls. These students were not very motivated to attend school successfully, since they were students that had difficulties and failed one ornmore years. The CEFs were created to allow these students to finish their academic studies, in a less constrained pedagogical environment, that provided access to professional studies
Populational analysis of Saccharomyces cerevisiae strains from different appellations of origin and grape varieties by microsatellite analysis.
The objective of the present study was to evaluate populational relationships among Saccharomyces cerevisiae strains isolated from some of the Portuguese most important grapevine varieties in different appellations of origin, using polymorphic microsatellites. 
One hundred ninety two grape samples were collected during the 2006 and 2007 harvest season in the Vinho Verde (grape varieties: Arinto, Alvarinho, Avesso, Loureiro, Touriga Nacional) Bairrada (grape varieties: Arinto, Baga, Castelão Francês, Maria Gomes, Touriga Nacional) Alentejo (grape varieties, Aragonês, Trincadeira, Touriga Nacional), Terras do Sado (grape variety Castelão) Bucelas (grape variety Arinto) and Estremadura (grape varieties: Arinto, Aragonês, Castelão, Trincadeira, Touriga Nacional) appellations of origin. From the final stage of spontaneous fermentations, 2820 yeast isolates were obtained, mainly belonging to the species S. cerevisiae. An initial genetic screen, based on mitochondrial DNA restriction fragment length polymorphism (mtDNA RFLP) and/or interdelta sequence analysis was followed by microsatellite analysis of strains with unique genetic profiles, using 10 highly polymorphic microsatellites. Our results showed that microsatellite analysis revealed a high resolution populational screen, showing that genetic differences and populational structures among S. cerevisiae populations derived from both “diagnostic” vineyard-, specific alleles and the accumulation of small allele-frequency differences across ten microsatellite loci. Heterozygosity was three to four times lower than the expected value, confirming the strong populational substructuring. The presented large-scale approach shows that each vineyard contains differentiated S. cerevisiae populations, showing the occurrence of specific native strains that can be associated with a terroir. 

Financially supported by the programs POCI 2010 (FEDER/FCT, POCTI/AGR/56102/2004) and AGRO (ENOSAFE, Nº 762).

Sulfonic Acid-Functionalized (Bio)Materials as Catalysts for Efficient Amide Bond Synthesis
Funding Information: The authors thank Fundação para a Ciência e Tecnologia (FC&T) for project PTDC/BII‐BIO/30884/2017 and EXPL/BII‐BIO/0436/2021 and also for the researcher contract 2021.03255.CEECIND (M.C.C) and 2020.01614.CEECIND/CP1596/CT0007 (A.F.P.). Authors also thank the support by the Associate Laboratory for Green Chemistry – LAQV, which is financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020) and i3 N (LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 . The National NMR Facility is supported by FC&T (ROTEIRO/0031/2013 – PINFRA/22161/2016, co‐financed by FEDER through COMPETE 2020, POCI, and PORL and FC&T through PIDDAC) and CERMAX through project 022162. We thank Prof. Dr. Carlos A. M. Afonso from the Faculty of Pharmacy, ULisboa for the scientific discussions on the experiments carried out with furfuryl alcohol derivatives. Publisher Copyright: © 2023 The Authors. ChemCatChem published by Wiley-VCH GmbH.Sulfonic acid carbon-(bio)based and natural clays-based catalysts were prepared and investigated for the first time as heterogeneous catalysts for amide bond synthesis by a Ritter reaction. The different SO3H-catalysts were screened using benzyl alcohol and acetonitrile as model substrates, and MWCNT-CSP revealed to be an efficient catalyst, affording the amide in 75 % yield. The practical utility of the catalysts was demonstrated by a diverse range of amides, obtained from alcohols and nitriles, in moderate to good yields. Biomass derived platform alcohols, such as 5-HMF and furfuryl alcohol, were also tested as potential building blocks for the synthesis of biopolymers. The SO3H-catalysts revealed to be a highly efficient and environmentally friendly alternative to the conventional acid catalysts commonly used in the Ritter reaction.publishersversionpublishe
Comparative genomics of wild type yeast strains unveils important genome diversity
<p>Abstract</p> <p>Background</p> <p>Genome variability generates phenotypic heterogeneity and is of relevance for adaptation to environmental change, but the extent of such variability in natural populations is still poorly understood. For example, selected <it>Saccharomyces cerevisiae </it>strains are variable at the ploidy level, have gene amplifications, changes in chromosome copy number, and gross chromosomal rearrangements. This suggests that genome plasticity provides important genetic diversity upon which natural selection mechanisms can operate.</p> <p>Results</p> <p>In this study, we have used wild-type <it>S. cerevisiae </it>(yeast) strains to investigate genome variation in natural and artificial environments. We have used comparative genome hybridization on array (aCGH) to characterize the genome variability of 16 yeast strains, of laboratory and commercial origin, isolated from vineyards and wine cellars, and from opportunistic human infections. Interestingly, sub-telomeric instability was associated with the clinical phenotype, while Ty element insertion regions determined genomic differences of natural wine fermentation strains. Copy number depletion of <it>ASP3 </it>and <it>YRF1 </it>genes was found in all wild-type strains. Other gene families involved in transmembrane transport, sugar and alcohol metabolism or drug resistance had copy number changes, which also distinguished wine from clinical isolates.</p> <p>Conclusion</p> <p>We have isolated and genotyped more than 1000 yeast strains from natural environments and carried out an aCGH analysis of 16 strains representative of distinct genotype clusters. Important genomic variability was identified between these strains, in particular in sub-telomeric regions and in Ty-element insertion sites, suggesting that this type of genome variability is the main source of genetic diversity in natural populations of yeast. The data highlights the usefulness of yeast as a model system to unravel intraspecific natural genome diversity and to elucidate how natural selection shapes the yeast genome.</p
A reabilitação da rede rodoviária no século XXI : a contribuição da inovação para uma visão global da reabilitação rodoviária
Este artigo aborda a temática da reabilitação da rede rodoviária no contexto dos seus
desafios para o futuro próximo. Inicialmente é feita uma abordagem da prática corrente dos
processos seguidos na reabilitação e do seu impacto nos custos do ciclo de vida dos
pavimentos. A seguir apresenta-se uma visão global da contribuição da reabilitação para a
qualidade de vida. Por fim aborda-se o papel da inovação na engenharia rodoviária ao serviço
da sociedade, compreendendo a inovação ao nível da qualidade de circulação e a construção e
conservação sustentável dos pavimentos rodoviários
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