Anais da Academia Brasileira de Ciencias最新文献

Floristic studies were conducted in three rocky cerrados, two limestone (designated as A1 and B) and one arenitic (A2), in the Pontal do Triângulo Mineiro region. We aimed to identify floristic patterns of their shrub-tree components that could contribute to the characterization of these rocky cerrados, especially the limestone ones. We surveyed 20 plots (10 m x 10 m) in areas A1 and A2, and 85 quadrants in B. To understand the species' contributions in terms of habitat occurrence, we classified then as generalists (G), savanna-associated (S), or forest-associated (F), and identified those occurring in rocky environments. We studied species richness through rarefaction curves and performed floristic similarity analyses using UPGMA (Jaccard index - between A1 and A2) and NMDS (Horn index - among the three rocky cerrados, 15 savanna areas, and eight deciduous forest areas). We observed a lower occurrence of strict savanna or forest species and rocky environments in all three studied areas, confirming findings from other authors. Despite a higher similarity with savanna formations, floristic differences recorded locally (UPGMA) and regionally (NMDS) supported the hypothesis that limestone cerrados may exhibit floristic patterns distinguishing them from other rocky cerrados.

Microorganisms from the Antarctic continent have attracted attention due to their ability to produce bioactive secondary metabolites at low temperatures. The search for pigmented compounds produced by microbial strains from cold environments has been investigated due to their applications in the cosmetics and pharmaceutical industries. This study evaluated the resistance to UV-C (254 nm) light and antimicrobial activity of pigments produced by soil bacteria from Deception Island, Antarctica. Ten pigmented bacteria were isolated and subjected to an assay for resistance to ultraviolet (UV) radiation. All strains showed resistance. However, six, five, and five strains were able to survive after 10, 15, and 30 minutes of light exposure. UV-resistant strains UVBACD.10 and Brachybacterium paraconglomeratum UVBACD.5 were selected for the minimum inhibitory concentration (MIC) assay against pathogenic bacteria. UVBACD.5 showed inhibitory effects on the pathogenic bacteria tested at different concentration levels, assayed in triplicate. The best antimicrobial activity reached a MIC of 0.021 mg mL-1 against Escherichia coli. Soil from Whalers Bay can be considered a source of microorganisms of industrial biotechnological interest. The results of this work encourage studies on the characterization and purification of secondary metabolites produced by isolates from the Antarctic continent for future applications in the pharmaceutical and cosmetic areas.

This study assessed the growth, gonadal development, first maturation, sperm quality, and first reproduction of Colossoma macropomum raised under controlled conditions. The animals were maintained under consistent conditions. The mean weights reached after the first, second, and third years were 0.94 kg (0.50-1.42 kg), 3.78 kg (3.02-5.19 kg), and 5.66 kg (3.88-8.17 kg), respectively. The highest biomass was 14.1 kg/m³ at 890 days after hatching (DAH), while at the end of the study it was 5.6 kg/m³. Feed conversion remained below 2.0. No differences in weight or length were observed between males and females of the same age. Of the three males analyzed at 590 DAH, one was at rest and two were in initial maturation. Advanced male maturation was first recorded at 710 DAH. Six females showed initial maturation at 710 DAH, while advanced female maturation was first recorded at 890 DAH. Data on VFI, HSI, and GSI throughout development are presented. Sperm quality parameters did not differ between males at 890 and those at 990 DAH. Two out of four induced females spawned. This study is the first to provide evidence suggesting that the life cycle of C. macropomum can be completed in RAS.

Numerical simulation of CO2-enhanced oil recovery (CO2-EOR) critically advances hydrocarbon field development by quantifying multiphase saturation dynamics during CO2-driven displacement. This study establishes a cylindrically configured 1D triple-phase mathematical model integrating Darcy's law and mass conservation principles, employing an implicit pressure-explicit saturation (IMPES) finite-difference scheme to resolve spatiotemporal evolution of aqueous, oleic, and gaseous phase saturations. Systematic incorporation of chemical reaction kinetics, viscosity-pressure coupling, and dynamic relative permeability effects yields a novel computational framework for immiscible displacement analysis. Simulations reveal two governing mechanisms: 1) CO2-saturated fluid/rock interactions induce pore-throat dilation, amplifying effective flooding radii; 2) Wellbore-formation pressure differentials (ΔP) dictate CO2 plume propagation, where elevated ΔP expands repulsion radii and oil displacement annulus thickness. Paradoxically, increased reservoir porosity reduces annular confinement while diminishing displacement efficiency despite enhanced volumetric throughput, with simulations confirming persistent oil-rich annuli characteristic of non-miscible regimes. These findings provide actionable guidelines for optimizing CO2-EOR injectivity parameters and ensuring long-term carbon sequestration integrity in heterogeneous formations, bridging theoretical modeling with field-scale implementation strategies.

Faced with the increase in the demand for energy and the scarcity of certain natural resources, finding ways to avoid environmental imbalances has become an important focus in research. In Roraima, corn production is increasing and its processing generates tons of husks and cobs, and these residues are rich in xylose and glucose. In this context, lignocellulosic biomass is presented as a sustainable proposal for producing fermentable sugars. This residues and analyze the conditions used in the acid and enzymatic hydrolysis process. The residues were pretreated, and the fermentable sugars were quantified using dinitrosalicylic acid, and then identified with near-infrared spectroscopy. In the enzymatic process, the sugar concentration obtained was 72.08 g L-1 for the husks and 69.94 g L-1 for the cobs. In the acid hydrolysis, 18.18 g L-1 was obtained for the husks and 19.20 g L-1 for the cobs, with xylose and glucose identified as the main sugars. These results suggest that these residues can serve as sustainable alternatives for producing fermentable sugars in the northern region of Brazil, given the growth in corn plantations. This sustainable approach aligns with efforts to address energy demands while mitigating environmental impacts.

Helicobacter pylori is an oncobacteria that infects more than half of the world's population. Adhesins are virulence factors that are essential for the microorganism to bind to the gastric mucosa, such as the BabA adhesion protein, which is associated with the clinical outcome of the infection. The aim of this study was to evaluate the association of the babA2 gene of H. pylori with clinical outcomes and lifestyle of dyspeptic patients in central Brazil. Molecular diagnosis of H. pylori and screening of the babA2 gene were performed in 155 patients by polymerase chain reaction. Gastropathies were classified as mild and severe. Approximately 68% (105/155) of the patients were infected with H. pylori, and of these, 25% had babA2+ strains. The presence of babA2 was more frequent in women and in patients who consumed coffee daily. However, there was no statistical association between babA2 and these variables. Approximately 31% of patients infected with babA2+ strains presented some severe disease, with gastric adenocarcinoma being the most frequent severe gastropathy. The babA2 genotype of H. pylori was not associated with the severity of gastropathies (p=0.128). The characterization of molecular markers may contribute to the identification of virulent strains with relevance to public health.