Anais da Academia Brasileira de Ciencias最新文献

A "comb-dentition", characterized by long, needle-like, and closely-spaced teeth, is found in the ctenochasmatid pterosaurs as an adaptation for filter-feeding. However, little is known about their tooth replacement pattern, hindering our understanding of the development of the filter-feeding apparatus of the clade. Here, we describe the tooth replacement of the pterosaur Forfexopterus from the Jehol Biota based on high-resolution X-ray Computed Tomography (CT) reconstruction. As in the ornithocheirid Coloborhynchus, the tooth germs are relatively medially positioned along the middle line; the replacement teeth erupt at the posteromedial side of the functional tooth; no more than one replacement tooth present in each alveolus. The replacement teeth are less than half of the length of the full-grown tooth, and alternatively positioned along the tooth row. The alternatively-positioned young and mature functional teeth are dominant and abrased, maintaining the active tooth-tooth occlusion of the filter-feeding apparatus. Reconstruction of Zahnreihen shows an average Z-spacing of 2.02, comparable to that of the simple alternate replacement (Z-spacing = 2) between odd- and even-numbered tooth positions in reptiles. Based on comparisons with Balaenognathus, Ctenochasma, and Pterodaustro, the tooth replacement pattern appears to be varied in ctenochasmatids, and needs to be further studied in the future.

Pterosaur remains are rare from the lowermost Cretaceous, hampering our understanding of the taxonomic and morphological diversities of pterosaurs during this period. The Lower Cretaceous Tugulu Group in Wuerho, China is renowned for hosting the Wuerho Pterosaurian Fauna (WPF), which has so far yielded numerous fossil remains of two dsungaripterid pterosaurs, Dsungaripterus weii and Noripterus complicidens. Here we report a partial ornithocheiromorph humerus from the WPF, representing a deeply divergent clade from Dsungaripteridae. The scarcity of ornithocheiromorphs from the WPF might be interpreted by niche partitioning with dsungaripterids. Meanwhile, we also report a U-Pb zircon age of 134.27 ± 0.36 Ma dated by LA-ICP-MS for the tuffaceous layer at the uppermost part of the Shengjinkou Formation, confirming the Valanginian age of the WPF presented by a previous study. The Wuerho region is one of the few localities producing abundant pterosaur fossils and the only one with an earliest Cretaceous age. The new finding here also suggests that Ornithocheiromorpha had rapidly diversified and achieved a global distribution during the earliest Cretaceous, presumably through a series of modifications on the locomotor apparatus including the warped deltopectoral crest of the humerus, which might substantially improve their flight efficiency.

Latency in flux observation has an adverse effect on the performance of observer-based field-oriented speed control for three-phase induction motor (IM). The reduction of the convergent rate of estimation errors could improve the performance of speed-controlled IM based on flux observers. The main contribution is to design a fast convergent flux observer, which provides bounded estimation error immediately after one instant of motor startup. The proposed flux observer fused barrier function adaptive mechanism with integral sliding mode control principle to yield BFISMO. Rigorous stability analysis has been conducted to achieve global flux estimation error ultimate boundedness. Moreover, three controllers have been designed. The first control design is devoted to flux control based on a backstepping controller, while the other two controllers' design is dedicated to rotor speed control of the motor. The speed controller is developed by combining the backstepping control with disturbance observers to estimate the unmatched load torque named quasi-sliding mode observer (QSMDO), and nonlinear disturbance observer (NLDO). Based on numerical simulations, the performance and efficacy of the proposed BFISMO have been assessed by conducting a comparison study to other observer techniques. The results showed the superiority of the proposed observer over the conventional versions.

The exploration of extraterrestrial environments has become a focal point of scientific inquiry, driven by advancements in technology and a growing interest in the potential for life beyond Earth. This study investigates the adaptability of Antarctic nematodes, known for thriving in extreme cold and isolation, to simulated Martian (MGS-1) and Lunar (LMS-1) soils. The experiment revealed differential responses in nematode survivability to the two simulants, with Lunar soil demonstrating better adaptability compared to Martian soil. Our study provides valuable insights into the potential survivability of Antarctic nematodes on real Martian and Lunar substrates with the use of the MGS-1 and the LMS-1 under terrestrial conditions. The observed results suggest differential survival responses to Lunar (6.92 ± 0.74) and Martian (5.58 ± 1.91) regolith simulants and highlight the complexity of factors influencing organismal survival. Considering their crucial role in soil food webs, and their relation with nutrient cycling and carbon dioxide emissions, the observed capacity of nematodes to thrive in Martian and Lunar regoliths positions them as potential candidates to sustain human habitats, helping on the development of in-situ resource utilization (ISRU) systems, and forming the basis for a biological life-support system to facilitate human survival in extraterrestrial environments.

The region of the Maritime Antarctic suffers significantly from climate change, resulting in regional warming and consequently affecting coverage. This study characterized three surface zones of Collins Glacier and three other zones in ice-free areas on the Fildes Peninsula, which has an area of 29.6 km². We used TerraSAR-X satellite images from 2014 to 2016 and analyzed the influence of meteorological and environmental conditions on these surface zones. We used five images from the TerraSAR-X satellite, three of these data were obtained during the same period of fieldwork. The classification considered three classes on the glacier (higher moisture, transition in moisture, and lower moisture) and three on the ice-free areas (wet snow, transition wet snow-bare ice, and bare ice), using Maximum Likelihood and ISODATA methods. In low-altitude glaciers with maritime influence, such as Collins, monitoring variations in surface zones is essential because the continuous increase in exposed ice may indicate potential retreat. The TerraSAR-X images enabled the classification of land features, highlighting the potential for continuous monitoring in the Maritime Antarctic, regardless of weather conditions and solar illumination.

The whole plant Saccocalyx satureioides, an endemic medicinal plant in Algeria, was evaluated for its polyphenolic contents, antioxidant and antimicrobial activities. The polyphenolic contents of the plant methanolic extracts ranged from 170.47 to 285.56 (µg GAEs/mg extract) and from 25.39 to 82.68 (µg QEs/mg extract), respectively. High antioxidant activity was registered: DPPH average IC50 = 14.68 µg/mL, and β-carotene average IC50 = 21.08 µg/mL. The essential oil and methanolic extracts from the aerial parts and roots were tested against bacteria and molds. Different methods, including disk diffusion, well diffusion, and microdilution tests for bacteria, were used. The essential oil (February and June harvest periods) value 1.25 µL/mL was the MIC and the MBC for all bacterial strains, except E. coli, K. pneumonia and Ps. aeruginosa. The average fungal inhibition of the methanol extracts ranged from 5.10 to 71.25%, except for F. oxysporum. The essential oil effect was 6.67-83.53% and 17.01-90.57% by the food poisoned and fumigation methods, respectively. The preliminary phytochemical evaluation demonstrated the high polyphenolic contents and effective antioxidant power of the plant extracts. This may have an essential role in the antimicrobial effectiveness and indicate that the plant contains high-quality bioactive molecules in addition to the essential oil.

Polar marine macroalgae thrive in extreme conditions, often displaying geographic isolation and high degree of endemism. The "phycosphere" refers to the zone around the algae inhabited by microrganisms. Our study used DNA metabarcoding to survey the eukaryotic communities associated with seven seaweed species obtained at King George Island (South Shetland Islands, maritime Antarctic), including two Rhodophyta, two Chlorophyta and three Phaeophyceae. The ITS2 region was used as a barcode and our analysis yielded 77 eukaryotic ASVs spanning five Kingdoms (Fungi, Metazoa, Chromista, Protozoa, and Viridiplantae) and ten phyla (Ascomycota, Basidiomycota, Cercozoa, Ciliophora, Ochrophyta, Amebozoa, Chlorophyta, Rhodophyta, Bryophyta and Cnidaria). Additionally, we identified 14 potential new occurrence records for Antarctica. Ciliates and green algae were the most species-rich groups. The most abundant assigned associated species was Monostroma angicava (Chrorophyta). Within the macroalgal, the Chlorophyceans Ulothrix sp. hosted the greatest number of taxa, followed by Monostroma hariotii. Our data suggested that Antarctic macroalgae host a rich diversity of associated organisms and the biodiversity associated with the phycosphere remains underestimated.

The Byers Peninsula, the largest ice-free area in Maritime Antarctica, is vital for studying landscape-scale natural processes due to its diverse periglacial landforms. This study aim to characterize the soils and environments of its southern sector, focusing on soil-landform-lithology interactions. Thirty-seven soil profiles were classified, collected, and chemically and physically analyzed. Principal component analysis explored relationships among variables in these profiles and 36 others from the Peninsula project database. The soils are generally shallow, with lithic or paralithic contact within the first meter. Four main soil groups were identified: patterned-ground soils on plateaus, ornithogenic soils, non-ornithogenic soils, and non-ornithogenic sodic and sandy soils on beaches and marine terraces. The Peninsula, divided into six geological units, represents a diverse periglacial morphogenetic system. Sixteen landform types were identified, each associated with different processes, topographies, lithologies, altitudes, and orientations, highlighting the importance of periglacial morphogenesis. Stable soilscapes, such as upper cryoplanation platforms, raised beaches, volcanic plugs, and ornithogenically influenced areas, show greater soil development and weathering. In contrast, dynamic periglacial landforms like scree stony slopes and talus exhibit minimal soil development and instability. The Byers Peninsula's pedodiversity is due to its varied lithologies, landforms, extensive ornithogenic influences from seabirds, and long-term vegetation establishment.

In the present study, 5-Hydroxy-2-(Oleoyloxymethyl) -4H-pyran-4-one (KMO 3), and their chelated with Cu(II) and Fe(III) ions were synthesized to explore their inhibitory activity against tyrosinase and cytotoxicity. To this end, the structures of the obtained compounds were confirmed by ATR/FT-IR, 13C and 1H-NMR, and UV-vis techniques. The results show that chelating fatty ester presents the bands at 1567m, 1511w cm-1 attributed to the coordinated carbonyl (Cu(II)←[O=C]2), and the bands at 1540m, 1519m cm-1 which were attributed to the coordinated carbonyl (Fe(III)←[O=C]3). The inhibitory effect of chelating Oleic acid 2 (inhibition 68.3% ± 4.5) showed a factor of 19 times higher than free fatty acid (3.6% ± 3.2). IC50 Anti-tyrosinase activity of the Kojic acid 1 and KMO 3 compounds were 62.8 ± 6.6 µM and 77.6 ± 4.3 µM. The IC50 and IC90 values for tyrosinase inhibitory activity for chelating fatty ester and their complexes are values > 400 µM. Finally, the assay with the series showed no hemolytic activity (EC50> 250 μg mL-1), and not cytotoxic to B16F10, ACP-02, and human dermal fibroblast cells at 100 µM and showed no hemolytic potential at the concentration of IC50 250 µM.