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The paleoenvironmental and thermal histories of the Permian Irati formation shale in the paraná basin, Brazil: An integrated approach based on mineralogical and organic imprints
Full text linkABSTRACT: Mineralogical assemblages and organofacies are important sources of information to recover the paleoenvironmental and thermal histories of shale deposits. In this study, a detailed qualitative and quantitative characterization of the Permian Irati Formation (Assistência Member) shale is based on mineralogical (XRD and SEM-EDS) and organic components (TOC, Rock-Eval pyrolysis, organofacies, TAI, fluorescence and vitrinite reflectance measurements) and provides integrated data about sediment provenance, depositional environment, diagenesis, and thermal history, while supporting interpretations on the Paraná Basin (PB), Brazil, paleogeography and its correlation to the southwest Gondwana. The results revealed a prevailing type I/II kerogen, with type III kerogen being also present but mainly confined along the paleoshoreline of the PB. The dominance of fluorescent amorphous organic matter (AOM) combined with framboidal pyrite suggests microbial activity in an anoxic-dysoxic neritic-marine paleoenvironment. Additionally, common to abundant well-preserved phytoclasts, as well as the occurrence of Botryococcus braunii, indicates freshwater influx in a brackish marine depositional setting. Immature to early-oil window thermal maturities prevail across the PB, according to the organic maturation indicators. The combined analysis between the organic matter evolution with clay mineralogy, such as the occurrence of interstratified clays (e.g., I/S) and its positive correlation with depth suggest that burial diagenesis reached the transition to early catagenesis on the north, southeast, and south of the basin, attributing a shale oil potential for the Irati Formation on a regional scale. Local scale imprints of the Early Cretaceous Paraná-Etendeka Large Igneous Province (LIP), and its thermal effect in the Irati Formation shale components, are recorded as clay authigenesis (e.g., smectite webby texture and clay coating development), crystallization of minerals by low to high-grade of thermal alteration (e.g., corrensite, talc, lizardite and diopside), and by local scale gas-window maturities. Such thermal alteration, identified in the proximity to intruded sills and dykes, led to a heterogeneous organic maturation pattern with implications on shale gas and shale oil potential of the Irati Formation shale, demonstrating that these subjects in the Paraná Basin should be assessed locally.info:eu-repo/semantics/publishedVersio
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)
No full textABSTRACT: 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
Synthesis of novel pyrazolo[3,4-b]quinoline-bisphosphonic acids and an unexpected intramolecular cyclization and phosphonylation reaction
No full textABSTRACT: Novel pyrazolo[3,4-b]quinoline alpha-ketophosphonic and hydroxymethylenebisphosphonic acid compounds were synthesized using different methodologies, starting from 2-chloro-3-formylquinoline 1. New phosphonic acid compounds were obtained as N-1 derivatives with a side chain with 1 or 3 (n = 1 or 3) methylene groups. All phosphonic acid compounds and their corresponding ester and carboxylic acid precursors were fully characterized, and their structures elucidated by spectroscopic data, using NMR techniques and infrared and high-resolution mass spectroscopy. During the process to obtain the N-1 substituted derivative with two methylene groups (n = 2) in the side chain, an unexpected addition-cyclization cascade reaction was observed, involving the phosphonylation of an aromatic ring and the formation of a new six-member lactam ring to afford a tetracyclic ring system. This was an unexpected result since other pyrazolo[3,4-b]quinoline derivatives and all corresponding pyrazolo[3,4-b]pyridine derivatives already prepared, under similar experimental conditions, did not undergo this reaction. This domino reaction occurs with different phosphite reagents but only affords the six-member ring. The spectroscopic data allowed the identification of the new synthesized tetracyclic compounds and the X-ray diffraction data of compound 11 enabled the confirmation of the proposed structures.info:eu-repo/semantics/publishedVersio
An insight into the firing conditions of Chinese blue-and-white porcelain through XANES
No full textABSTRACT: Chinese blue-and-white porcelain is found in archaeological excavations worldwide, being significant evidence of global trade routes and cultural exchange. Synchrotron radiation-based techniques have been applied for studying cobalt speciation to establish a correlation between the cobalt and iron oxidation state and local coordination environment in the rich blue shades of Chinese blue-and-white porcelain. However, the relationship between the firing atmosphere conditions and the speciation of cobalt has not been established yet. In this study, underglaze blue models were produced and fired in air or under reducing atmospheres to ascertain the effect of the firing atmosphere in cobalt and iron speciation. The experimental results were compared with data obtained on historical samples of ancient porcelain shards. The microstructure and colour of the produced underglaze blue models were investigated by variable pressure scanning electron microscopy (VP-SEM-EDS), using a hyperspectral imaging camera (Vis-SWIR reflectance spectroscopy) and colorimetry. The formal valence and coordination of cobalt and iron ions of the glaze were determined by X-ray absorption spectroscopy (XAS), particularly X-ray absorption near edge structure (XANES), using synchrotron radiation. Spectral features demonstrated that both cobalt and iron speciation were affected by the firing atmosphere and therefore could be used to ascertain the firing atmosphere.info:eu-repo/semantics/publishedVersio
Development of a bench-scale photobioreactor with a novel recirculation system for continuous cultivation of microalgae
No full textABSTRACT: Microalgae cultivation can be used to increase the sustainability of carbon emitting processes, converting the CO2 from exhaust gases into fuels, food and chemicals. Many of the carbon emitting industries operate in a continuous manner, for periods that can span days or months, resulting in a continuous stream of gas emissions. Biogenic CO2 from industrial microbiological processes is one example, since in many cases it becomes unsustainable to stop these processes on a daily or weekly basis. To correctly sequester these emissions, microalgae systems must be operated under continuous constant conditions, requiring photobioreactors (PBRs) that can act as chemostats for long periods of time. However, in order to optimize culture parameters or study metabolic responses, bench-scale setups are necessary. Currently there is a lack of studies and design alternatives using chemostat, since most works focus on batch assays or semi-continuous cultures. Therefore, this work focused on the development of a continuous bench-scale PBR, which combines a retention vessel, a photocollector and a degasser, with an innovative recirculation system, that allows it to operate as an autotrophic chemostat, to study carbon sequestration from a biogenic CO2-rich constant air stream. To assess its applicability, the PBR was used to cultivate the green microalga Haematococcus pluvialis using as sole carbon source the CO2 produced by a coupled heterotrophic bacterial chemostat. An air stream containing ≈0.35 vol% of CO2, was fed to the system, and it was evaluated in terms of stability, carbon fixation and biomass productivity, for dilution rates ranging from 0.1 to 0.5 d−1. The PBR was able to operate under chemostat conditions for more than 100 days, producing a stable culture that generated proportional responses to the stimuli it was subjected to, attaining a maximum biomass productivity of 183 mg/L/d with a carbon fixation efficiency of ≈39% at 0.3 d−1. These results reinforce the effectiveness of the developed PBR system, making it suitable for laboratory-scale studies of continuous photoautotrophic microalgae cultivation.info:eu-repo/semantics/publishedVersio
New electricity markets: The challenges of variable renewable energy
No full textABSTRACT: The development and large-scale dissemination of the new and variable renewable technologies took place from 1990 onwards in most developed countries, in a process led by Europe. To promote the renewable sector development financial incentives, both for investment and for the payment of renewable energy, were always present. These incentives usually consisted of guaranteed feed-in tariffs that ensured a return of the investments made in this new business—thus minimizing the financial risks and building a more attractive business for private companies in the renewables sector. That approach was the main basis that essentially supported the remarkable growth of the renewable sector in Europe in the past 30 years. Nowadays, the renewable energy sector is already mature in most aspects. The cost of generating electricity from wind or solar (photovoltaic) resources is competitive with conventional gas or coal-based technologies. However, some challenges still exist in the transition of the electrical power sector to a desirable carbon-free, near 100% renewable-based sector—and one of those main challenges is the negotiation of the electricity generated by these novel technologies, due to the time and spatial variability of the primary resources as well as their poor predictability and dispatchability of the power generated. This chapter addresses those challenges as well as the approaches available to overcome them within competitive electricity markets.info:eu-repo/semantics/publishedVersio
In-Depth Inhomogeneities in CIGS Solar Cells: Identifying Regions for Performance Limitations by PIXE and EBS
No full textABSTRACT: When considering materials to be used as active layers in solar cells, an important required parameter is the proper knowledge of their elemental composition. It should be heavily controlled during growth in order to obtain the desired band gap and to decrease the recombination defects and then increase the solar cell electrical performance. Ion beam analytical (IBA) techniques and, in particular, particle-induced X-ray emission (PIXE) and elastic backscattering spectrometry (EBS) are quite suitable to determine the thickness and composition of such active layers. Furthermore, if these techniques are performed using a nuclear microprobe, lateral and in-depth inhomogeneities can be clearly observed from 2D maps. In many cases, composition variations can be detected from the classical 2D maps obtained from the PIXE spectra. In this work, it is shown how the in-depth variations can also be studied when considering 2D maps reconstructed from the EBS spectra. Such variations are derived from processing conditions and can be related to (i) composition, (ii) thickness, (iii) roughness, and (iv) other nontrivial issues. Examples obtained on Cu(In,Ga)Se-2-based cells are presented and discussed. Furthermore, the combination of IBA techniques such as PIXE and EBS is shown to be a competitive and alternative method to the more used and established techniques such as X-ray fluorescence for checking the average composition of the solar cell active layers or secondary ion mass spectroscopy for determination of the elemental depth profile.info:eu-repo/semantics/publishedVersio
Enhanced borohydride oxidation kinetics with Au@MOF-808 nanocomposite electrocatalysts with ultra-low Au loading
No full textABSTRACT: 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
Windscanner.PT: National Research Infrastructure
No full textABSTRACT: This document presents a contribution to the project's activities, developed under Task#4 and Task #5 of the WindScanner.PT Research Infrastructure (PINFRA/22207/2016). The main activities developed under this project were the Business Plan and Governance Structure related with legal documentation, and data processing and modelling, related with field experiments using Lidars. The Business Plan and Governance Structure are detailed in two separate reports developed by LNEG and IPB. In this sense, this report summarises the content of these two reports, and the details are presented on Annexes I and III of this document. In addition to the business plan elaboration, a budgeting tool was developed to support the RI activities and is presented in Annex II. In this project, two research fellowships were foreseen by LNEG, and both the contracted students contributed to the development of the Business Plan and Governance Structure.
In addition, they have also contributed to the knowledge on data processing and modelling, using Lidar sensors and other data sources. The activities' reports are presented in Annexes IV and V of this document. Finally, this document, presents the indicators achieved at the end of the project.N/