Browsing by Issue Date, starting with "2024-08"
Now showing 1 - 10 of 17
Results Per Page
Sort Options
- ARQUEOLIT: an open access lithotheque in Portugal [Resumo]Publication . Jordão, Patrícia; Soares, Sofia; Silva, Teresa
- Geochemical Map of Latin America and the Caribbean: Methods for implementation [Resumo]Publication . Batista, Maria Joao; Turel, A.; Martin, I.; Larizzatti, João; Prieto, G.ABSTRACT: The Geochemistry Experts Group of the Ibero-American Association of Geological Services is a group of experts who exchange knowledge on exploration geochemistry and geochemical mapping as a result of the experience of each Geological Service. Currently, the group of experts has started to test the methodology for collecting information for the Geochemical Map of Latin America. The continental data unit used is the Global Terrestrial Network (GTN), following the recommendations for International Geochemical Mapping, but instead of 160x160 km, it will have a 40x40 km cell. The geochemical data will be collected in each cell, and an average value (median or geometric mean) will be determined.
- Ionic liquids toward enhanced carotenoid extraction from bacterial biomassPublication . Silva, Tiago; Alves, Luís; Salgado, Francisco; Roseiro, J. Carlos; Lukasik, Rafal M.; Paixão, Susana M.ABSTRACT: Carotenoids are high added-value products primarily known for their intense coloration and high antioxidant activity. They can be extracted from a variety of natural sources, such as plants, animals, microalgae, yeasts, and bacteria. Gordonia alkanivorans strain 1B is a bacterium recognized as a hyper-pigment producer. However, due to its adaptations to its natural habitat, hydrocarbon-contaminated soils, strain 1B is resistant to different organic solvents, making carotenoid extraction through conventional methods more laborious and inefficient. Ionic liquids (ILs) have been abundantly shown to increase carotenoid extraction in plants, microalgae, and yeast; however, there is limited information regarding bacterial carotenoid extraction, especially for the Gordonia genus. Therefore, the main goal of this study was to evaluate the potential of ILs to mediate bacterial carotenoid extraction and develop a method to achieve higher yields with fewer pre-processing steps. In this context, an initial screening was performed with biomass of strain 1B and nineteen different ILs in various conditions, revealing that tributyl(ethyl)phosphonium diethyl phosphate (IL#18), combined with ethyl acetate (EAc) as a co-solvent, presented the highest level of carotenoid extraction. Afterward, to better understand the process and optimize the extraction results, two experimental designs were performed, varying the amounts of IL#18 and EAc used. These allowed the establishment of 50 µL of IL#18 with 1125 µL of EAc, for 400 µL of biomass (cell suspension with about 36 g/L), as the ideal conditions to achieve maximal carotenoid extraction. Compared to the conventional extraction method using DMSO, this novel procedure eliminates the need for biomass drying, reduces extraction temperatures from 50 °C to 22 ± 2 °C, and increases carotenoid extraction by 264%, allowing a near-complete recovery of carotenoids contained in the biomass. These results highlight the great potential of ILs for bacterial carotenoid extraction, increasing the process efficiency, while potentially reducing energy consumption, related costs, and emissions.
- New pollen taxon Syncolpraedapollis angolensis nov. gen. sp. nov.: A noteworthy discovery reported in the preliminary investigation of the latest Eocene-latest Oligocene deposits in the Kwanza Basin, AngolaPublication . Mendes, Márcia; Pereira, Zélia; Rodrigues, Cristina F.A.; Nsungani, Nsungani, P.C.ABSTRACT: A palynostratigraphic study of the upper Cunga and lower Quifangondo deposits in the Cabo de São Brás section, Kwanza Basin, Angola, has revealed a new pollen named Syncolpraedapollis angolensis nov. gen. sp. nov. This finding was part of a wider survey in the upper Cunga and lower Quifangondo deposits of the Cabo de São Brás section, Kwanza Basin, Angola, covering the latest Eocene to the latest Oligocene. The novel pollen features unique characteristics, notably a 3-syncolporate structure with well-defined and distinctive pores. The pollen grain is adorned with a free but irregular reticulum with an irregular polygonal mesh. Syncolpraedapollis angolensis nov. gen. sp. nov. is sporadically but consistently observed within the latest Eocene-latest Oligocene interval, conspicuously absent in the underlying Eocene sediments (lower Cunga Formation) and occurring infrequently in the latest Oligocene sediments (lower Quifangondo Formation). Thus, it is plausible to infer a limited age range, likely restricted to the latest Eocene-latest Oligocene, as previous studies in the Kwanza Basin have not documented this pollen.
- Depth estimation of pre-Kalahari basement in Southern Angola using seismic noise measurements and drill-hole dataPublication . Carvalho, João; Alves, Daniela; Borges, José Fernando; Caldeira, Bento; Cordeiro, Domingos; Machadinho, Ana; Oliveira, Álvaro; Ramalho, Elsa; Rodrigues, José Feliciano; Llorente, J.; Ditutala, M.; Lobón, Jose Luis Garcia; Máximo, J.; Carvalho, Cristina Isabel Paulo; Labaredas, José; Ibarra, P.; Manuel, JoséABSTRACT: The remote Southern region of Angola is covered by siliciclastic Kalahari Cenozoic formations that host underground aquifers of great importance to local populations affected by water scarcity problems. These aquifers are well developed where Kalahari sands reach appropriate thicknesses. On the other hand, at the eastern end of this area, regional aeromagnetic data recently acquired suggested the possibility of the continuity of the geological structures of the Lufilian Arc, sited in the nearby Zambia and Congo, southwestwards into Angola under the Kalahari formations. Once the Lufilian Arc is associated with the presence of the so-called Central African Copperbelt, this possibility increased the interest in determining the depth to Pan-African rocks under the Kalahari basin. To estimate the thickness of Kalahari formations in this area of difficult access and poor logistics, an expedited and non-invasive geophysical method was needed. Seismic noise and the single-station Nakamura technique were chosen, but due to the large distance of the study area from the ocean, one of the major sources of seismic noise, a test survey was acquired in the Cuvelai region to assess the signal quality, where the data was calibrated using available drill-holes. >170 points of seismic ambient noise were later acquired and the horizontal/vertical (HVSR) amplitude versus frequency curves were 1D inverted for the best velocity/density model for each station. The results were compared with 1D inverted legacy vertical electrical soundings reprocessed and validated in this work, showing similar depth-to-basement, while interpreted velocities/densities of geological formations were sampled and confirmed with measurements. A depth-to-basement map was produced using seismic information, mechanical soundings, and geological information. Despite the relatively reduced geographical area covered, the map presents valuable information for hydrogeology and mineral exploration purposes and agrees with a previously available coarser map of Kalahari thickness and with observations from geological surveys simultaneously conducted at the time of the seismic surveys.
- Overview of geochemical mapping in the Geological Surveys of Ibero-America [Resumo]Publication . Martín-Méndez, I.; Batista, Maria Joao; Prieto, G.; Turel, A.ABSTRACT: In recent years, the Geological Surveys of Ibero-America have collaborated through the Association of Iberoamerican Geological and Mining Surveys (ASGMI) experts group to exchange information about the status of the different geological and mining activities in the region and to share experiences in geosciences programs in each country. The Geochemistry Expert Group (GEGOQ-ASGMI) has proposed the development of a manual of geochemical methodologies (Batista et al. 2023) employed by as its main ASGMI member countries that could be used for other countries to promote their knowledge of geochemistry and its applications.
- Decoding Portuguese Azulejos: the intersection of art, history, and science [Resumo]Publication . Veiga, JP; Coutinho, ML; Coentro, S.; Silva, TeresaABSTRACT: In recent decades, the production techniques of azulejos (Portuguese glazed tiles with predominantly blue color) remain a subject of ongoing research. Combining historical research with advanced analytical techniques, this communication aims to show that pigments and materials that define the azulejo colour palette, along with their production recipes and the chemical and structural composition of the glazed tiles. This communication highlights the application of synchrotron radiation to the analysis of Portuguese azulejos. Some examples will be presented, namely the Co and Cu K-edge Xray absorption near-edge spectroscopy (XANES) results performed on glazed tiles from the Fronteira Palace, in Lisbon and the speciation of pigments from Pena National Palace, Sintra. The speciation state of certain chemical elements provides an understanding of their role as chromophores, glass network formers or modifiers, contributing to a deeper knowledge of the production techniques, provenance, and the tiles’ history of use. The non-destructiveness nature allied to the high-resolution capabilities of synchrotron radiation chemical imaging offer a unique tool for investigating cultural heritage materials, enhancing our understanding of their composition, structure, and degradation processes, and contributing to their long-term preservation and interpretation for future conservation efforts.
- A Preliminary Overview of the Metallogenetic Provinces of Southern Angola [Resumo]Publication . Merino-Martínez, E.; Batista, Maria Joao; Martín-Méndez, I.; de Oliveira, Daniel Pipa Soares; Feria, María Carmen; Fortes, Carla; Prazeres, Cátia; García-Lobón, J. L.; Manuel, JoséABSTRACT: The distinct mineralisations found in the Republic of Angola make it an area of significant interest due to its metallogenic potential. These occurrences often have a spatial distribution and form mineral associations related to specific geological areas and environments. However, given the growing global demand for mineral resources, it is crucial to comprehend a country's regional mining potential. This knowledge is essential for effective territorial planning and future exploration and research of its resources. For this reason, the Government of the Republic of Angola, through the Ministry of Natural Resources, Oil and Gas (MIREMPET) and the Geological Institute of Angola (IGEO), implemented the National Geological Plan of Angola (PLANAGEO, 2014-2022). The main aim of PLANAGEO was to establish a detailed and comprehensive geological framework, facilitating a thorough interpretation of the identified geophysical and geochemical anomalies, as well as the geological processes responsible for the recognised mineralisations.
- Tracing lithic raw materials from Outeiro do Circo (Beja, Portugal): portable x-ray fluorescence (pXRF) utility [Resumo]Publication . Soares, Sofia; Silva, Teresa; Serra, Miguel; Porfírio, Eduardo; Silva, Sofia
- Innovative approach in sustainable agriculture: Harnessing microalgae potential via subcritical water extractionPublication . Ferreira, Alice; Vladic, Jelena; Corrêa, D. O.; Butzke, Valéria Louzada Leal; Martins, Pedro L.; Ribeiro, Belina; Santos, Cláudia Marques dos; Acién, F. Gabriel; Gouveia, LuisaABSTRACT: Microalgae can contribute to sustainable agriculture and wastewater treatment. This study investigated Tetradesmus obliquus, grown in piggery wastewater (To-PWW), as a biostimulant/biofertilizer compared to biomass grown in synthetic medium (To-B). Subcritical water extraction was tested for disruption/hydrolysis of wet biomass, at three temperatures (120, 170, and 220 °C) and two biomass loads (1:10 and 1:80 (g dry biomass/mL water)). Extracts were evaluated for germination, and root formation/expansion. Residues were quantified for nutrient composition to assess their biofertilizer potential and tested for their affinity to oil compounds for bioremediation. The best germination was achieved by To-B extracts at 170 °C (1:10: 148 % at 0.2 g/L, 1:80: 145 % at 0.5 g/L). Only To-PWW extracts at 0.2 g/L had a significant germination effect (120 °C: 120–123 % for both loads; 170 °C: 115 % for 1:80). To-PWW extract at 120 °C and 1:10 significantly affected cucumber and mung bean root formation (224 and 268 %, respectively). Most extracts significantly enhanced root expansion, with all To-B extracts at 1:10 showing the best results (139–181 %). The residues contained essential nutrients (NPK), indicating their biofertilizer potential, helping decrease synthetic fertilizers demands. To-B residues had high affinity to toluene and diesel but lower to used cooking and car oils. To-PWW showed very low affinity to all oil compounds. Finally, all residues were only able to form stable emulsions with the used car oil. This study fully exploits the use of microalgal biomass in sustainable agriculture, producing biostimulant extracts, and residues for biofertilizer and bioremediation, from a low-cost wastewater source.