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- Hydrogen production using vinasse as sacrificial agent and Pt/TiO2 as photocatalyst under UV irradiation2024 - 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.
- Effect of gamma radiation on human enamel chemical and physical properties2024 - 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.
- Direct synthesis of graphene layers on a final-use surface2025 - 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.
- CD39 regulates P2RX7-mediated lung necrotic lesions in severe experimental tuberculosis2025 - 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’IMPERIOTuberculosis 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.
- A new methodology for muscle phenotyping by Raman spectroscopy2025 - BATISTA, ANDRE M.; PASCOAL, DIEGO C.; ALVES, PAULA K. N.; DUTRA, LUIS A. C. H. C.; MORISCOT, ANSELMO S.; WETTER, NIKLAUS U.; FREITAS, ANDERSON Z.Muscle fiber types perform distinct functions in skeletal muscle tissue, allowing a wide range of physical and motor capabilities. The characterization of these fibers is essential in several research fields, however, the methodologies currently used are quite expensive and time-consuming. Here we successfully demonstrate that Raman spectroscopy, combined with chemometric methods such as PCA, can distinguish different types of skeletal muscle fibers in the soleus muscle. Distinct spectral variations associated with tryptophan, phenylalanine, tyrosine, and the Amide I band were identified as critical biomarkers to differentiate fiber types. In addition, we highlight the structural changes of protein-related bands, demonstrating transitions and providing experimental evidence for conformational changes linked to muscle function. Our new methodology for detecting spectral patterns offers valuable insights into the biochemistry of muscle cells, enabling the identification of specific types of skeletal muscle fibers and paving the way for further investigations into these cells under various conditions, such as atrophy, hypertrophy, and sarcopenia.
- Numerical study of electron acceleration in structured CNT targets via self-injection in a wakefield bubble driven by an 800 nm laser2025 - BONTOIU, CRISTIAN; BONATTO, ALEXANDRE; APSIMON, OZNUR; BANDIERA, LAURA; CAVOTO, GIANLUCA; DREBOT, ILLYA; GATTI, GIANCARLO; GINER-NAVARRO, JORGE; LEI, BIFENG; MARTIN-LUNA, PABLO; RAGO, ILARIA; RODRIGUEZ PEREZ, JUAN; NUNES, BRUNO S.; SYTOV, ALEXEI; VALAGIANNOPOULOS, CONSTANTINOS; WELSCH, CARSTEN; XIA, GUOXING; ZHANG, JIAQI; RESTA-LOPEZ, JAVIERLaser wakefield acceleration (LWFA) may achieve TeV/m gradients using high-density solid-state plasmas as accelerating media. However, the application of bulk solid materials requires attosecond laser pulses, such as X-ray lasers, to drive wakefields at these high densities. Additionally, the short wakefield wavelengths associated with solid-state plasmas greatly limit the accelerating length. An alternative approach employs 2D carbon-based nanomaterials, like graphene or carbon nanotubes (CNTs), configured into structured targets. These nanostructures are designed with voids or low-density regions to effectively reduce the overall plasma density. This reduction enables the use of longer-wavelength lasers and also extends the plasma wavelength and the acceleration length. In this study, we present, to our knowledge, the first numerical demonstration of electron acceleration via self-injection into a wakefield bubble driven by an infrared laser pulse in structured CNT targets, similar to the behavior observed in gaseous plasmas for LWFA in the nonlinear (or bubble) regime. Using the PIConGPU code, bundles of CNTs are modeled in a 3D geometry as 25 nm-thick carbon tubes with an initial density of 10²² cm⁻³. The carbon plasma is ionized by a three-cycle, 800 nm wavelength laser pulse with a peak intensity of 10²¹ W cm⁻², achieving an effective plasma density of 10²⁰ cm⁻³. The same laser also drives the wakefield bubble, responsible for electron self-injection and acceleration. Simulation results indicate that fs-long electron bunches with hundreds of pC charge can be self-injected and accelerated at gradients exceeding 1 TeV/m. Both charge and accelerating-gradient figures are unprecedented when compared with LWFA in gaseous plasma.
Preprint IPEN-doc 32080 Radiation effects on Eu-complex-doped PMMA and nanosilver compounds after exposure to γ-irradiation2025 - ZAHARESCU, TRAIAN; PARRA, DUCLERC F.; LIMA, VINICIUS da S.; LUGAO, ADEMAR B.The evaluation of the stability of PMMA/europium (III) complexes with various ligands: 3-thenoyltrifluoroacetonate (TTA), triphenyl phosphine oxide (TTPO) and water assisted by g-irradiation is the goal of this study. The nonisothermal chemiluminescence (CL) measurements reveal the dependence of this stability on the filler concentration. The values of onset oxidation temperature (OOT) obtained from CL spectra are the basic characterization criteria, which are correlated with the sample composition, the irradiation dose and the environment containing the radiolysis fragments. The systems investigated were the luminescent systems PMMA:Ag:Eu(tta)3 and PMMA:Ag:Eu(tta)3(tppo)2 obtained from the PMMA doped with europium (III) complexes. The inclusion of silver nanoparticles into the molecular structures of complexes diminishes the rate of oxidation through the mechanism of RO. scavenging by action of the nanosilver. The Europium ion emitter, surrounded by the ligand had Eu(III) luminescence enhancement, rationalized by the local field enhancement produced by the surface plasmons in silver NPs. The results indicate that these materials have optical marker properties for integrating special devices subjected to high energy transfers.Preprint IPEN-doc 32079 Low-resolution neural networks2025 - CABRAL, EDUARDO L.L.; DRIEMEIER, LARISSAThe expanding scale of large neural network models introduces significant challenges, driving efforts to reduce memory usage and enhance computational efficiency. Such measures are crucial to ensure the practical implementation and effective application of these sophisticated models across a wide array of use cases. This study examines the impact of parameter bit precision on model performance compared to standard 32-bit models, with a focus on multiclass object classification in images. The models analyzed include those with fully connected layers, convolutional layers, and transformer blocks, with model weight resolution ranging from 1 bit to 4.08 bits. The findings indicate that models with lower parameter bit precision achieve results comparable to 32-bit models, showing promise for use in memory-constrained devices. While low-resolution models with a small number of parameters require more training epochs to achieve accuracy comparable to 32-bit models, those with a large number of parameters achieve similar performance within the same number of epochs. Additionally, data augmentation can destabilize training in low-resolution models, but including zero as a potential value in the weight parameters helps maintain stability and prevents performance degradation. Overall, 2.32-bit weights offer the optimal balance of memory reduction, performance, and efficiency. However, further research should explore other dataset types and more complex and larger models. These findings suggest a potential new era for optimized neural network models with reduced memory requirements and improved computational efficiency, though advancements in dedicated hardware are necessary to fully realize this potential.