Submissões Recentes
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Hydrogen production using vinasse as sacrificial agent and Pt/TiO2 as photocatalyst under UV irradiation
2024 - SILVAINO, PATRICIA F.; FERREIRA, JOAO C.; CARMINATI, SAULO A.; VAZ, JORGE M.; SPINACE, ESTEVAM V.
Vinasse, a dark-colored aqueous byproduct of bioethanol production, contains a variety of organic compounds and inorganic salt ions. In this study, vinasse was utilized as a sacrificial agent in the water-splitting reaction using Pt/TiO₂ as a photocatalyst under UV irradiation. The gaseous products generated were analyzed, revealing the formation of hydrogen (H₂) along with other gases, including CO₂, CH₄, CO, C₂H₆, C₂H₄, C₃H₈, and C₄H₁₀. When filtered vinasse was used as the sacrificial agent, H₂ and other gaseous products were produced solely through photolysis, even in the presence of the Pt/TiO₂ photocatalyst. Notably, H₂ production from the water-splitting reaction was enhanced when inorganic salt ions were removed from the vinasse and lower vinasse concentrations were employed in the reaction medium.
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Effect of gamma radiation on human enamel chemical and physical properties
2024 - SILVA, POLLYANNA N. F. da; BARCELLOS, MARIA C. F.; COSTA, FERNANDA C.; SILVA, CELIO dos S.; MANEA, SILVIO; GONCALEZ, ODAIR L.; JARDIM, VITOR R.; MARTINS, GISLENE V.; LIMA, NELSON B.; FOUND, ANELYSE A.; SOUZA, GRACE M. de; KAMINAGAKURA, ESTELA; TANGO, RUBENS N.
Background: Gamma radiation is still used in developing countries for the treatment of head and neck cancer. Irradiated dental enamel undergoes dose-dependent chemical and mechanical changes that can hinder oral rehabilitation. Understanding these processes can help professionals plan safer and longer-lasting treatments. This study aimed to evaluate the effects of different doses of gamma radiation on the chemical and mechanical properties of human dental enamel. Methods: Sixty human third molars were divided into six groups (n = 10) according to radiation dose: 0, 20, 40, 50, 60, or 70 Gy, administered in daily fractions of 2 Gy. After irradiation, enamel composition and the carbonate-to-phosphate ratio (C:P) were evaluated by Fourier Transform Infrared Spectroscopy (FTIR). X-ray diffraction (XRD) was used to assess crystal size (shape factor) and crystallinity. Hardness, elastic modulus, and scratch resistance were measured, and the microstructure was observed by scanning electron microscopy (SEM). Data for C:P, crystallinity (%), shape factor (nm), hardness (VHN – Vickers Hardness Number), and elastic modulus (GPa) were submitted to analysis of variance and Tukey’s test (α = 0.05). Results: FTIR revealed the presence of carboxylic acid groups in the irradiated samples and an increase in the C:P ratio for the 70 Gy group (p = 0.015), although no changes were observed in the crystalline structure. A significant decrease in hardness (p = 0.0000) and elastic modulus (p = 0.0000) was observed in the irradiated groups. In the scratch test, the 60 and 70 Gy groups showed lower values for initial spallation. SEM images revealed spaced and rounded enamel prism peaks in the 60 and 70 Gy groups. Conclusions: Gamma radiation negatively affected the chemical and mechanical properties of human dental enamel.
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Direct synthesis of graphene layers on a final-use surface
2025 - BONIFACIO, RAFAEL N.; SILVA, BARBARA P. G.; OTUBO, LARISSA; SOUZA, RODRIGO F. B. de; OLIVEIRA NETO, ALMIR; LAZAR, DOLORES R. R.
The simultaneous synthesis and application of graphene-layered (graphenoid) materials directly onto a surface, or the direct construction of specific structures using this type of material, could lead to significant developments in various scientific fields. In this study, graphene layers were synthesized and directly applied to a target surface using an instantaneous reduction method based on the incidence of an electric arc that reduces cyclohexane vapor on the surface. The surface evaluated was fiberglass, a material with a curved shape and high contact angle, representing a challenging, or even worst-case, scenario for such depositions. As a result of the process features, as well as its evaluation at different time intervals, graphene-layered structures with varying shapes, thicknesses, roughness, porosities, and topographical profiles were obtained. Furthermore, the formation of compact and mechanically resistant structures was also observed. Throughout the study, the key attributes of this method were presented and discussed, demonstrating its potential to advance the field of direct synthesis and application of graphene-based materials.
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CD39 regulates P2RX7-mediated lung necrotic lesions in severe experimental tuberculosis
2025 - ALMEIDA-SANTOS, GISLANE; SANTIAGO-CARVALHO, IGOR; ALMEIDA, FABRICIO M.; BOMFIM, CAIO C. B.; SANTOS E SILVA, JUAN C.; CANTARINI, DEBORAH G.; SILVA, CAMILA R.; RIBEIRO, MARTHA S.; MACEDO, BRUNA de G.; RAEDER, PAULO H. L.; TEIXEIRA-XAVIER JUNIOR, JOAQUIM; ALVAREZ, JOSE M.; HIRATA, MARIO H.; COUTINHO-SILVA, ROBSON; ROBSON, SIMON C.; AMARAL, EDUARDO P.; LASUNSKAIA, ELENA; LIMA, MARIA R. D’IMPERIO
Tuberculosis induces diverse lesions, such as necrotic pneumonia, contributing to disease progression and transmission. Despite advances in understanding the role of ATP-gated P2RX7 ion channels in the development of severe forms of tuberculosis, the regulation of this important signaling pathway remains unclear. Herein, we show that the ectonucleotidase CD39 plays an essential regulatory role in tuberculosis progression by preventing lung tissue damage, bacterial dissemination, and excessive inflammatory responses. Mechanistically, through its enzymatic activity on the cell surface, CD39 protects infected macrophages from undergoing necrotic death mediated by P2RX7 activation. We propose that, by protecting macrophages from P2RX7-mediated cell death and bacterial dissemination, CD39 prevents the development of necrotic lesions. Altogether, these findings uncover a significant role for CD39 as an essential component of the molecular regulation underlying the development of severe tuberculosis.