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- Namibe Group detrital zircon U-Pb and Lu-Hf isotopes: a testimony of late-Orosirian (1.9–1.8 Ga) crustal growth in the Angolan Shield (Congo Craton)Publication . Ferreira, Ezequiel; Lehmann, Jeremie; Rodrigues, José Feliciano; Silva, Paulo Bravo; Smith, Trishya M. Owen; García-Lobón, J. L.; Correia, João; Ueckermann, Henriette; Molekwa, Mmasetena Anna; Manuel, José; Victorino, Américo da MataABSTRACT: The Namibe Group represents the largest package of immature supracrustal rocks of the Angola Shield (Congo Craton), occupying an area of nearly 10,000 km2 in the Namibe Zone (NZ). It is a folded, steeply dipping, meta-volcanosedimentary sequence essentially comprising immature micaschists and greywackes, felsic metavolcaniclastites, along with intercalated marbles and amphibolites. The metavolcanosedimentary sequence is intruded by ca. 1810–1790 Ma ultramafic to felsic plutonic rocks with magmatic arc geochemical signatures. Despite its importance, key aspects such as its maximum depositional age (MDA), sedimentary provenance, and the detrital zircon (DZ) record of crustal evolution remain unresolved. This study presents LA-ICP-MS U-Pb and Lu-Hf DZ analyses from nine NG samples.
- Nanobubble-enhanced oxygen transfer in bacterial nanocellulose production: Comparative evaluation with static and airlift systemsPublication . Rodrigues, Ana Cristina; Martins, Daniela; Carvalho, Ricardo; Marques, Susana; Belo, Isabel; Espina, Begona; Dourado, Fernando; Gama, MiguelABSTRACT: Despite the unique properties of bacterial nanocellulose (BNC), oxygen limitation during large-scale production impairs microbial metabolism and cellulose synthesis, leading to high production costs and limited commercial success. Static fermentation can achieve high titers, but industrially it is operationally challenging. Agitated systems like airlift (AL) bioreactors, allow faster production but typically yield lower titers. This study pioneered the use of an agitated bioreactor equipped with a nanobubble (NB) generator, and its performance was compared with that of static and AL systems, employing a newly isolated Komagataeibacter sp. strain from kombucha cultivated in Eucalyptus bark hydrolysate and corn steep liquor. Key monitored parameters included dissolved oxygen, cell density, pH, sugar and lactic acid contents, and BNC production. The obtained BNC was characterized for its crystallinity, thermal stability, degree of polymerization, morphology and fiber size. The AL-and NB-derived BNC exhibited a denser network structure, lower crystallinity index, and lower polymerization degrees than that from static culture. NB technology generated stable nanobubbles (size: 95.8 f 12.9 nm; zeta potential:-14.2 f 8.6 mV). At 1 L. min-1 airflow, compared to AL, the NB bioreactor achieved a 6-fold higher volumetric mass transfer coefficient (kLa 35.9 f 1.2 h-1) and oxygen transfer rate (OTR: 309.7 f 10.2 mg.L-1.h-1). It supported greater cell density but maintained a similar BNC volumetric productivity to that of the AL (0.023 g.L-1.h-1), and moderately higher (near 280%) than that of static culture (0.0082 g.L-1.h-1). Thus, the improved oxygen levels provided by the NB system favored biomass growth rather than BNC production, suggesting that further optimization is needed to redirect carbon flux toward BNC production.
- Sustainable Production of Poly(3-hydroxybutyrate) Using Eucalyptus Bark: Integration with Green Downstream ProcessingPublication . Matias, João; Rodrigues, Thomas; Torres, Cristiana A. V.; Marques, Susana; Ribeiro, Belina; Gírio, Francisco; Reis, Maria A.; Freitas, FilomenaABSTRACT: This study integrates the valorization of a lignocellulose material into poly(3-hydroxybutyrate), P(3HB), with biopolymer extraction from bacterial cells with the enzyme alcalase. The work focused on Burkholderia thailandensis DSM 13276 as the P(3HB) producer and on eucalyptus bark, a byproduct from the pulp industry, as the sole feedstock for bacterial cultivation. The eucalyptus bark was hydrolyzed by a cellulolytic enzymatic cocktail following steam explosion and further subjected to ultrafiltration for enzyme recovery. The resulting hydrolysate supported good cell growth, achieving a cell dry weight of 7.67 +/- 0.16 g/L within 72 h of cultivation, and high P(3HB) content (60.0 +/- 2.19 wt %) in the bacterial cells, clearly favoring biopolymer synthesis over cell growth, as demonstrated by the polymer and growth yields (0.190 gP(3HB)/gsugar and 0.026 gX/gsugar, respectively). High extraction efficiency (96%) and biopolymer purity (100 +/- 3.38%) were reached by enzymatic treatment, resulting in a sample with properties aligned with those of commercial P(3HB) in terms of molecular mass distribution, crystallinity, and thermal properties. These findings demonstrate the successful use of a sustainable feedstock together with the application of environmentally friendly technologies based on the use of enzymes for both lignocellulosic saccharification and biopolymer recovery to develop high-quality bioplastics, advancing the goals of a circular bioeconomy.
- Mid-Neoproterozoic extensional tectonics in the Larsemann Hills, East Antarctica: Implications for Indo-Antarctic correlation in RodiniaPublication . Chatterjee, Sandro; Dev, J. Amal; Debnath, Aishi; Ghosh, Anuj; Dey, Soham; Mukherjee, Anik; Arora, Devsamridhi; Tomson, Joseph Kallukalam; Guimarães, Fernanda; Pant, Naresh Chandra; Gupta, SaibalABSTRACT: The supercontinents Rodinia and Gondwana are believed to have assembled through orogenic events at similar to 1000 Ma and similar to 550 Ma, respectively. The Larsemann Hills, part of the extended Rayner Complex of East Antarctica, is a Neoproterozoic granulite terrane that was a part of both supercontinents. The tectonic evolution of the terrane in the Rodinia to Gondwana interval remains uncertain. This study integrates new field, microstructural, metamorphic and geochronological information to unveil a previously undocumented mid-Neoproterozoic thermo-tectonic event in the Larsemann Hills. Granulite facies metamorphism (M-1), synchronous with the deformation, D-1, is interpreted to have occurred in the Larsemann Hills at similar to 1000 Ma, followed by a crustal shortening (D-2) event that continued from similar to 990-900 Ma, signifying the incorporation of the Rayner crustal unit into Rodinia. Subsequent mid-Neoproterozoic extensional deformation (D-3), characterized by NW-SE trending S-3 shear zones, reoriented pre-existing structural fabrics. The extensional deformation operated under amphibolite facies metamorphic conditions (M-2) and resulted in a post-peak decompressive P-T trajectory. UPb LA-ICPMS dates on zircons separated from metapelites within high D-3 strain zone yield clusters at similar to 700 Ma; zircons immediately adjacent to the shear zone yield ages around similar to 990-900 Ma. A thermal overprint at similar to 550 Ma is evident but weakly manifested in the western Larsemann Hills, with no unambiguously correlatable structural or metamorphic evidence, suggesting distance from the Gondwana orogenic front. The extensional deformation documented here is contemporaneous with extension in the northern Eastern Ghats Province, India that was contiguous with the Rayner Complex in the Neoproterozoic. This suggests that a major terrane-wide extensional event was associated with the disintegration of Rodinia. In the Neoproterozoic, the EGP-Rayner unit was therefore a tectonic entity distinct from cratonic India, with only the former being an integral component of Rodinia.
- Enhanced borohydride oxidation kinetics with Au@MOF-808 nanocomposite electrocatalysts with ultra-low Au loadingPublication . Belhaj, Ines; Becker, J. Alexander; Viana, Alexandre M.; Gusmão, Filipe M. B.; Chaves, Miguel; Pereira, Eulália; Sljukic, Biljana; Balula, Salete S.; Silva, Luis Cunha; Santos, Diogo M. F.ABSTRACT: The highly stable metal-organic framework (MOF) composed of[Zr6O4(mu 3-OH)4(OH)6(H2O)6(BTC)2]& sdot;nH2O units (MOF-808) was modified by incorporating gold (Au) nanoparticles and functional groups to enhance electrocatalytic activity for the borohydride oxidation reaction (BOR). Three composite materials (Au@MOF-808, Au@MOF-808-NH2, and Au@MOF-808-SH) were prepared by the incorporation of Au in structurally related MOFs, MOF-808, MOF-808-NH2, and MOF-808-SH, respectively. These composite materials were evaluated as anodic electrocatalysts for BOR in alkaline media using cyclic voltammetry and chronoamperometry. Among the prepared materials, Au@MOF-808-NH2 exhibited the highest BOR activity, with an apparent activation energy of 15.3 kJ mol-1, a reaction order of 0.6, an anodic charge transfer coefficient of 0.63, and a number of exchanged electrons of 4.4. The latter was significantly below the theoretical eight-electron value, indicating the presence of alternative reaction pathways. Notably, this material achieved a high mass-specific BOR peak current of 4.23 A mu gAu-1, demonstrating outstanding electrocatalytic efficiency despite the ultralow noble metal loading. These results underscore the potential of Au@MOF-808-NH2 as a cost-effective and scalable anodic electrocatalyst for high-performance direct borohydride fuel cells.
- Novel fast synthesis route for α-MgAgSb thermoelectric materialsPublication . Santos, Beatriz; Sá, Ana; Luz, Paulo P. da; Neves, Filipe; de Boor, Johannes; Pereira Gonçalves, AntonioABSTRACT: Thermoelectric (TE) materials capable of waste heat recovery in the temperature range of 300-525 K remain relatively underdeveloped compared to conventional Bi2Te3-based systems, which present inherent environmental, health, and cost challenges. Recently, MgAgSb-based compounds have garnered significant research interest for applications in this temperature range owing to their intrinsically low thermal conductivity, high figure of merit and higher abundance. However, synthesis of the desired low-temperature alpha-MgAgSb phase typically requires highly controlled production processes-such as multi-step mechanical alloying, followed by extensive, week-long annealing-to mitigate the formation of or transition to undesirable phases. This study proposes an original, rapid, and scalable synthesis strategy combining induction melting for only six minutes with the subsequent classic hot-pressing method. We investigated the effect of nominal stoichiometry on thermoelectric performance by synthesising three distinct compositions: MgAg0.97Sb0.995, MgAg0.965Sb0.985, and MgAg0.955Sb0.985. The MgAg0.955Sb0.985 composition exhibited optimal performance, achieving an average power factor (PF) of 12.8 mu W K-2 cm-1 in the 300-525 K range. By considerably reducing the thermal budget and processing time, this approach significantly improves the energy payback time (EPBT) and reduces the carbon footprint of production, addressing the critical sustainability-performance trade-off that limits large-scale deployment. This result validates the capacity of the proposed fast synthesis route to yield performant MgAgSb-based samples and suggests that the optimal nominal composition is dependent on the specific production technique employed. Fundamentally, this work demonstrates the rapid and successful preparation of the desired alpha-MgAgSb phase using an easily scalable technique that does not require a perpetually inert atmosphere. This process utilises bulky precursor elements directly, significantly reducing production complexity, associated costs, and health hazards. This advancement provides a simpler and more industrially viable pathway for the transition of MgAgSb materials toward commercial availability.
- Noise-Induced fatigue in maritime work environments: A cross-sectional study of occupational exposure among seafaring personnel in IndonesiaPublication . Febriyanto, Kresna; Mourão, Luis; Matos, Maria Luísa; Guedes, JoanaABSTRACT: Objective: The study aims to examine the relationship between occupational noise exposure and the levels of physical, mental, and emotional fatigue among speedboat crew members.Methods: A cross-sectional study was conducted among speedboat crew members in Tarakan, North Kalimantan, Indonesia on November 2024. This study involves two categories of ship personnel as samples, namely, crew members and captains were 87 crews were enrolled in this study. We calculated using Spearman's rho models to analysed the data.Results: The study found that occupational noise levels on speedboats ranged from 77.9 to 100.9 dB(A), with one vessel exceeding the safe exposure threshold. The level of fatigue among the respondents is mostly in the low category (69% - 74.7%). Occupational noise aboard speedboats is a significant contributor to physical (r = .715, p = .040) and mental fatigue (r = .839, p = .022).Conclusion: The results of the statistical test indicate that, besides the main research variable, other confounding variables correlate with the fatigue levels of the crew, such as age, educational background, and working period. While overall fatigue levels were low, the study highlights the need to address noise exposure and other correlated factors to safeguard seafarers well-being.
- A segurança geológica como gargalo para a infraestrutura, transportes e habitação nas cidades diante das mudanças climáticasPublication . Rodrigues, I. R.; Dutra, A. C. D.; Santos, A. C.RESUMO: As mudanças climáticas têm ampliado a ocorrência de eventos extremos, como chuvas intensas, deslizamentos e inundações, afetando principalmente áreas urbanas e infraestruturas vulneráveis. Este artigo discute a segurança geológica como um dos principais gargalos na sustentabilidade das cidades brasileiras, impactando diretamente os setores de infraestrutura, transportes e habitação. A partir de uma abordagem analítico-interpretativa e revisão bibliográfica, analisam-se os entraves técnicos, institucionais e sociais que dificultam a prevenção de desastres. Os resultados indicam que a ausência de mapeamentos de risco atualizados, a falta de comunicação com as comunidades e a integração entre os setores dificultam a implementação de ações preventivas. Ressalta-se que, diante dos eventos extremos, é comum que as rotas de acesso e evacuação sejam obstruídas, comprometendo a resposta a emergências. Conclui-se que a integração entre conhecimento geocientífico, planejamento urbano e participação comunitária é fundamental para fortalecer a resiliência urbana.