Physicochemical investigation of shrimp fossils from the Romualdo and Ipubi formations (Araripe Basin)

The Ipubi and Romualdo Formations are Cretaceous units of the Araripe Basin (Santana Group). The first and most ancient was deposited in a lake environment, and some fossils were preserved in shales deposited under blackish conditions. The second was deposited in a marine environment, preserving a rich paleontological content in calcareous concretions. Considering that these two environments preserved their fossils under different processes, in this work we investigated the chemical composition of two fossilized specimens, one from each of the studied stratigraphic units, and compared them using vibrational spectroscopy techniques (Raman and IR), X-ray diffraction and large-field energy-dispersive X-ray spectroscopy (EDS) mappings. Calcite was observed as the dominant phase and carbon was observed in the fossils as a byproduct of the decomposition. The preservation of hydroxide calcium phosphate (Ca10(PO4)6(OH)2, hydroxyapatite) was observed in both fossils. In addition, it was observed that there was a smaller amount of pyrite (pyritization) in the Romualdo Formation sample than in the Ipubi one. Large-field EDS measurements showed the major presence of the chemical elements calcium, oxygen, iron, aluminum and fluoride in the Ipubi fossil, indicating a greater influence of inorganic processes in its fossilization. Our results also suggest that the Romualdo Formation fossilization process involved the substitution of the hydroxyl group by fluorine, providing durability to the fossils

Síntese de templates para aplicação em piezocerâmicas livre de chumbo

As piezocerâmicas de chumbo a base de Pb(Zr1-xTix)O3 (PZT) sempre tiveram destaque devido às suas excelentes propriedades piezoelétricas. Suas aplicações como sensores, atuadores e capacitores tornaram essas cerâmicas um alvo de incessantes estudos. Entretanto, cresce a necessidade de substituí-las devido ao impacto ambiental causado pelo chumbo. Com este objetivo, pesquisas em busca de materiais alternativos vêm ganhando destaque na comunidade científica internacional. Nesse contexto, os únicos materiais que apresentaram características equiparáveis ao PZT foram os niobatos alcalinos texturizados. Entretanto, para a obtenção dessas cerâmicas texturizadas foi necessária a produção de templates de niobato de sódio (NaNbO3) por complexos processos de síntese, uma vez que estes não estão disponíveis comercialmente. Nessa linha de estudo, o presente projeto de pesquisa buscou a síntese de moldes (templates) de niobato de sódio e de potássio para texturização de cerâmicas livres de chumbo a base de niobatos alcalinos (NaKLiNbO3) por método “Templated Grain Growth” (TGG) e “Reactive Templated Grain Growth” (RTGG). Os templates foram produzidos por síntese hidrotérmica assistida por microondas (H-M), a 200ºC, e com variações de tempo, tipo de precursor de nióbio e concentração de reagentes. Os templates de NaNbO3 e KNbO3 foram produzidos através da reação entre um precursor de nióbio (Nb2O5 ou NH4.NbO.(C2O4)2.(H2O)2.(H2O)n) e o hidróxido do respectivo metal alcalino (NaOH ou KOH). O NaNbO3 foi produzido com ambos os precursores de nióbio, embora o oxalato amoniacal favoreça a cristalização de partículas cúbicas de maior tamanho (>4μm). Durante a síntese do NaNbO3, as análises de difratometria de raios X (DRX) e de microscopia eletrônica de varredura (MEV) mostraram que as microfibras de Na2Nb2O6.nH2O formadas são uma fase intermediária...PZT-based materials [Pb(Zr1-xTix)O3] are the most used piezoceramics around the world due to their excellent piezoelectric properties. Their applications as sensors, actuators and capacitors made these ceramics the center of unceasing studies. However, the necessity of substituting these materials has been increased mainly because of the environment impact caused by the lead element. With this objective, new researches aiming the discovery of alternative materials have been growth in the scientific community. In this context, the only materials which presented properties at the level of PZT were the texturized alkalines niobates. Nevertheless, to produce such texturized ceramics, the use of complexes methods of synthesis was necessary to create templates of sodium niobate (NaNbO3), once they are not commercially available. Therefore, this project attempted to produce templates of sodium and potassium niobates intending the texturization of alkaline niobate-based ceramics (NaKLiNbO3) by Templated Grain Growth (TGG) and Reactive Templated Grain Growth (RTGG) methods. The templates were produced by means of a microwave assisted hydrothermal synthesis (M-H), at 200ºC, by varying the time, type of niobium precursor and reactants concentrations. The templates of NaNbO3 e KNbO3 were produced through the reaction between a niobium precursor (Nb2O5 or NH4.NbO.(C2O4)2.(H2O)2.(H2O)n) and the hydroxide of the respective alkaline metal (NaOH or KOH). The NaNbO3 was synthesized by both niobium precursors, though the niobium ammoniacal oxalate promoted the formation of cubic particles of NaNbO3 with greater sizes (>4μm). During the synthesis of the NaNbO3, the analysis of X-ray diffratometry (XRD) and scanning electronic microscopy (SEM) indicated that the microfibers of Na2Nb2O6.nH2O are formed as an intermediary phase towards the NaNbO3 crystallization... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

CO2 Reduction Beyond Copper-Based Catalysts: A Natural Language Processing Review From The Scientific Literature

Carbon dioxide (CO2) is a prominent greenhouse gas contributing significantly to global warming. To combat this issue, one strategy is the conversion of CO2 into alcohols and hydrocarbons, which can be utilized as fuels and chemical feedstocks. Consequently, a substantial volume of scientific literature has been dedicated to investigating different materials and reaction conditions to facilitate the CO2 reduction reaction (CO2RR) into these so-called high-value products. However, the vastness of this literature makes it challenging to stay updated on recent discoveries and review the most promising materials and conditions that have been explored. To address this issue, we applied natural language processing (NLP) tools to extract valuable data from 7292 published articles in the scientific literature. Our analysis revealed the emergence of new materials such as cesium-lead-bromide perovskites and bismuth oxyhalides, which have recently been used in CO2RR, and identified Bi-based catalysts as the most selective for HCOO – production. Furthermore, we gleaned insights into the composition of other elements and materials commonly employed in CO2RR, their relationship to product distribution, and the prevalent electrolytes used in CO2 electrochemical reduction (CO2ER). Our findings can serve as a foundation for future investigations in the realm of catalysts for CO2 reduction reactions, offering insights into the most promising materials and conditions to pursue further research

CO₂ Reduction beyond Copper-Based Catalysts: A Natural Language Processing Review from the Scientific Literature

Carbon dioxide (CO2) is a prominent greenhouse gas that contributes significantly to global warming. To combat this issue, one strategy is the conversion of CO2 into alcohols and hydrocarbons, which can be used as fuels and chemical feedstocks. Consequently, a substantial volume of scientific literature has been dedicated to investigating different materials and reaction conditions to facilitate the CO2 reduction reaction (CO2RR) into these so-called high-value products. However, the vastness of this literature makes it challenging to stay updated on recent discoveries and review the most promising materials and conditions that have been explored. To address this issue, we applied natural language processing tools to extract valuable data from 7292 published articles in the scientific literature. Our analysis revealed the emergence of new materials such as cesium–lead–bromide perovskites and bismuth oxyhalides that have been recently used in the CO2RR and identified Bi-based catalysts as the most selective for HCOO– production. Furthermore, we gleaned insights into the composition of other elements and materials commonly employed in the CO2RR, their relationship to product distribution, and the prevalent electrolytes used in the CO2 electrochemical reduction. Our findings can serve as a foundation for future investigations in the realm of catalysts for CO2RRs, offering insights into the most promising materials and conditions to pursue further research