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Deep learning-based segmentation of Jaszczak ACR phantom images for optimized Radium-223 dosimetry
2025 - GRIEBLER, CRISTIAN F.; CORDEIRO, LEANDERSON P.; LIMA, LUIS F.; BOLZAN, VAGNER; DUTRA, VITOR; SA, LIDIA V. de; BONIFACIO, DANIEL A.B.
Precise and personalized absorbed dose estimation in radionuclide therapy is crucial for optimizing treatment efficiency while minimizing harm to healthy tissues. Radium-223 dichloride (Ra-223), an alpha emitter used in treating metastatic castration-resistant prostate cancer, has shown positive results in extending patient survival. However, the current practice of uniform Ra-223 activity administration based solely on patient weight can lead to suboptimal treatment outcomes. Treatment efficacy evaluation involves quantifying activity and absorbed dose through image quality analysis, revealing potential areas for optimization. This work introduces an innovative approach that integrates a deep learning-based model for automated segmentation of the Jaszczak ACR phantom—a tool for image quality analysis in nuclear medicine—with Monte Carlo simulation for dosimetry. The model exhibits efficient segmentation, surpassing 83.7 % in class-wise Dice coefficients, offering a timeefficient alternative to manual segmentation. The study highlights the superior performance of the 89 keV energy window in image quality parameters, emphasizing its role in lesion detection. Additionally, it addresses challenges in achieving accurate quantitative outcomes in nuclear medicine applications, particularly in Ra-223 therapy. These insights contribute to refining dosimetry protocols for Ra-223, enhancing the precision of quantitative outcomes in nuclear medicine. The practical implications extend to improving daily routines for clinical professionals in nuclear medicine applications, showcasing the potential of advanced imaging techniques and computational tools in optimizing Ra-223 therapy.
Biomass-derived porous crystalline calcium-silicates synthesized from chicken eggshell waste using organic amine templates
2025 - GUARNIERI, GUILHERME de P.; SANTISTEBAN, OSCAR A.N.; CANCELLA, ERICK P.; AZEVEDO, EDUARDO R. de; COSENTINO, IVANA C.; MERCURI, LUCILDES P.; SANTORO, MARCELO L.; GODOY, MOACIR F. de; NERY, JOSE G.
Uncontrollable hemorrhage is a major cause of mortality in accidents, trauma, and medical procedures, highlighting the need for effective hemostatic agents. Zeolites and similar materials are promising due to their adsorption properties and ability to concentrate coagulation factors. This study reports the synthesis of calcium- silicates from chicken eggshell waste using TEA.OH, TPA.OH, and TBA.OH as templates. TPA.OH and TBA.OH direct the formation of rhodesite, a fibrous calcium-silicate, while TEA.OH results in quartz. Materials synthesized with TPA.OH and TBA.OH have surface areas of 53.3–100.3m2 g 1 and mesopores ranging from 5.7 to 27.7 nm with pore volumes of 0.018–0.11 cm3 g 1. In vitro coagulation assays (PT, aPTT) revealed that CaZ-3 and CaZ-4 activate factors within the contact system. The recalcification assay shows a significant reduction in clotting time, indicating action via the intrinsic pathway. Thromboelastographic analysis confirms high hemostatic performance: the material prepared with TBA.OH shows a shorter clot formation time (R=1.8 0.5min) and higher maximumclot strength (MA=52.1 1.3mm) than QuikClot, demonstrating its potential as an effective, waste-derived hemostatic agent.
Analysis of the proteome and biochemistry of venom from Tityus Confluens, a scorpion that can be involved in severe envenomation cases in Brazil
2025 - LIMA, LAIS C.; COVALI-PONTES, HENRIQUE R.; LEITE OHANNA G.S.; PERDOMO, RENATA T.; MORAES, LUIZ F.R.N. de; MIGLIOLO, LUDOVICO; MOYSES, MAURICIO N.; SANTOS, NATALIA G.P. dos; PIMENTA, DANIEL C.; RODRIGUES, MARIANA S.; MORAIS-ZANI, KAREN; COELHO, GUILHERME R.; LUCENA, MALSON N.
In Brazil, the annual scorpion sting cases surpass those of other neglected tropical diseases, highlighting a significant public health issue. The severity of scorpion envenomation relates to the venom’s rapid action, complex composition, species identification challenges, and limited antivenom availability. This work aimed to characterize the venom of Tityus confluens through proteomic, enzymatic, and biological analyses while also assessing its reactivity to anti-scorpion antivenom. The electrophoretic analysis revealed seven protein bands, with the most prominent bands at 30, 15, and 10 kDa. The C18-RP-HPLC analysis isolated sixteen primary fractions. The proteomic analysis identified various toxins, including potassium channel toxins, sodium channel toxins, and antimicrobial peptides, as well as other proteins such as hypotensin and metalloproteinases. Antigenic components were identified in the T. confluens venom, which displayed dose-dependent but time-independent amylolytic activity. The ATPase activity significantly increased with 1–10 μg of venom. No cytotoxic effects were observed on carcinoma or non-tumoral cell lines. The T. confluens venom features a complex protein composition rich in toxins that target ion channels and enzymes. It exhibits active enzymatic and antigenic properties, and displays low cytotoxicity. This is the first proteomic research on the composition of T. confluens venom and may provide valuable insights into understanding the clinical manifestations of scorpion stings.
Calibration of 90Sr + 90Y planar sources using thermoluminescent dosimeters, radiochromic film, a PMMA phantom and Monte Carlo simulation
2025 - LITVAC, DANIEL; CALDAS, LINDA V.E.
In some parts of Brazil, 90Sr + 90Y clinical applicators are still in use for dermatological and ophthalmic treatments, even with new technologies worldwide, because they are of lower cost and easier use. Calibration and periodic recalibration of these applicators to verify the absorbed dose rate is essential to ensure accuracy in clinical treatments. This work focused on an alternative calibration method for 90Sr + 90Y sources, utilizing thermoluminescent dosimeters, radiochromic films, and Monte Carlo simulation, following international recommendations. Regarding radiation doses, the thermoluminescent response of μLiF pellets and the response of radiochromic films were evaluated to determine reproducibility, linearity of response, and their dose-response curves. Additionally, radiochromic films were used to determine the dose rate distribution across the areas of the clinical applicators, and the μLiF dosimeters were used as a comparative measure in determining the axial central dose rate of clinical applicators. A PMMA phantom was developed and utilized to perform the calibrations. Monte Carlo simulation was essential for replicating the radioactive properties and correction factors for radiation and deposited doses in two media and at different distances from these sources. This work presents a practical and cost-effective method for calibrating planar 90Sr + 90Y radioactive sources; it was developed to serve locations that lack state-of-the-art technological resources, and was validated for effectiveness and broad applicability. The developed technique allows for long-distance calibration using dosimetric materials, provided they are properly handled and shielded.
Effects of ionizing radiation on the physicochemical properties of polyester multifilaments
2025 - MELO, CAMILA G.; SILVA, LEONARDO G. de A. e; ROSA, JORGE M.; CASTRO, DIONE P. de; PEREIRA, MARIA da C.C.
Polyethylene Terephthalate (PET), known nationally as Polyester (PES), is the most used fiber in the textile sector and stands out compared to natural fibers and other synthetic fibers due to its constant rise in production and consumption. In the search for sustainability in the textile industry, ionizing radiation presents itself as an environmentally correct process for modifying the properties of polyester fiber, through the formation of reactive species. This work aims to analyze the influence of ionizing radiation on the physicochemical properties of PES microfiber textile multifilaments. The samples were analyzed for toughness and elongation resistance, Thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR). The Cobalt-60 gamma irradiation process was effective in altering the properties of the microfiber multifilament analyzed, thus exposing important information on the effects of radiation applied to the polyester textile microfiber to adapt it to the demands of the end consumer.
Advanced analytical approaches for phenolic compounds in groundwater
2025 - SANTA-CRUZ-MERIDA, GIANCARLA V.; OTOMO, JULIANA I.; ARAOZ-PRADO, DIEGO R.; RODRIGUES, ELAINE A.; ANDRADE, DELVONEI A. de; BUSTILLOS, OSCAR V.
Groundwater is of vital significance to achieve the 2030 Agenda and its Sustainable Development Goals (SDGs); nevertheless, it remains vulnerable to contamination from phenolic compounds. This systematic review critically evaluates the chromatographic and spectrometric techniques applied in real-case groundwater contamination studies involving phenolic compounds. It highlights advances, limitations, and research gaps. A comprehensive research strategy retrieved a total of 345 publications from the Scopus andWeb of Science databases, of which 52 (from the years 1984 to 2023) met the PRISMA criteria. The review identified 107 phenolic compounds across 25 countries. Temporal and spatial analyses, source identification, and pollutant profiles were systematically assessed per country. The study also mapped priority (n = 11) and hazardous (n = 27) phenolic compounds according to the USEPA, comparing their detectability across analytical methods. The most frequently applied techniques were LC-MS and LC-MS/MS, while GC-MS demonstrated competitive performance when combined with derivatization. The study found that contamination was predominantly reported in the Global North, with industrial and domestic sewage being the main sources. The highest concentrations reported were 40 × 106 ng/L for 4-methylphenol and 50 × 106 ng/L for phenol, both of which are hazardous substances typically linked to industrial/domestic effluents and the use of pesticides. These findings highlight the imperative for regulatory measures and international scientific collaboration to enhance groundwater monitoring, particularly in the Global South, where data scarcity persists.
Assessment of the surface characteristics of ISO 5832-1 stainless steel for biomaterial applications
20256 - PIERETTI, EURICO F.; PIAGGIO, DAVIDE; COSTA, ISOLDA
Marking techniques are employed to guarantee the identification and traceability of biomedical materials. This study investigated the impact of laser and mechanical marking processes on the tribological performance of ISO 5832-1 austenitic stainless steel (SS), specifically examining corrosion resistance, the coefficient of friction, and wear volume in ball-cratering wear tests. The laser marking was performed using a nanosecond Q-switched Nd:YAG laser. Cytotoxicity tests assessed the biocompatibility of the biomaterial. Non-marked surfaces were also evaluated for comparison. A phosphate-buffered saline solution (PBS) served as both the lubricant and corrosion medium. The surface finishing was analyzed using optical microscopy and scanning electron microscopy coupled with a field-emission gun (SEM-FEG), combined with an energy-dispersive X-ray spectrometer. The oxide film was examined through X-ray photoelectron spectroscopy (XPS). Wear tests lasted 10 min, with PBS drops applied every 10 s at 75 rpm; solid balls of AISI 316L stainless steel (SS) and polypropylene (PP), each 1 inch in diameter, were used as counter-bodies. Corrosion resistance was assessed using electrochemical methods. Results showed variations in roughness and microstructure due to laser marking. The tribological behaviour was influenced by the type of marking process, and the wear amount depended on the normal force and ball nature. None of the samples was considered cytotoxic, although laser-marked surfaces exhibited the lowest cellular viability among the tested surfaces and the lowest corrosion resistance.
Characterization of a gelcast AISI 310 SS matrix composite reinforced by alumina and GNP particles
2025 - OLIVEIRA, LOUISE F.R.; ORTEGA, FERNANDO dos S.; MAGNABOSCO, RODRIGO; NEVES, MAURICIO D.M. das
Gelcasting is a versatile forming technique suitable for preparing composite materials with various powders, including metallic and ceramic particles, at any solids concentration. Despite its potential, the application of gelcasting to produce metal matrix composites reinforced with alumina and graphene remains limited. This study investigates the gelcasting of AISI 310 stainless steel composites reinforced with 1, 3, and 5 vol.% nanosized alumina and 0.5 vol.% graphene nanoplatelets (GNPs). Rheological behavior and particle interactions were analyzed to ensure uniform dispersion. Thermal analysis determined optimal sintering conditions, avoiding densification issues. Compression and microhardness tests revealed yield strengths of up to 285 MPa at room temperature (RT) and 140 MPa at 800 °C, exceeding ASTM A351/A351M-18e1 standards. Microstructural refinement and homogeneous alumina distribution were achieved, with 3 vol.% alumina providing the best performance. The gelcasting process proved effective for producing dense, mechanically robust composites at a low cost.
Bayesian optimization of laser wakefield acceleration in the self-modulated regime (SM-LWFA) aiming to produce molybdenum-99 via photonuclear reactions
2025 - NUNES, B.S.; SANTOS, S.P.; NUNES, S.P.; BONTOIU, C.; ALVA-SANCHES, A.S.; SAMAD, R.E.; JUNIOR VIEIRA, N.D.; XIA, G.; RESTA-LOPEZ, J.; BONATTO, A.
While laser wakefield acceleration (LWFA) in the bubble regime demands ultra-short, high-peak-power laser pulses, operation in the self-modulated regime (SM-LWFA) works with more relaxed pulse conditions, albeit at the cost of lower beam quality. Modern laser systems can deliver few-terawatt pulses with tens of femtoseconds at kilohertz repetition rates. These systems are well-suited for developing SM-LWFA applications where high average energy and charge are prioritized over beam quality. Such beams could be used to generate high-energy bremsstrahlung photons, capable of triggering photonuclear reactions to produce radioisotopes like molybdenum-99. This isotope decays into technetium-99m, the most widely used medical radioisotope, with over 30 million applications worldwide per year. This work explores the use of Bayesian optimization to maximize the energy and charge of electron beams accelerated via SM-LWFA. Particle-in-cell (PIC) simulations model a 5 TW, ~60 fs-long (FWHM) Gaussian laser pulse, propagating through tailored hydrogen gas-density profiles. In these simulations, over multiple iterations, the algorithm optimizes a set of input parameters characterizing the gas-density profile and the laser focal position. Three distinct profiles, with lengths ranging from 200 to 400 μm and combining ramps and plateaus, were investigated. Optimal configurations produced electron beams with median energies ranging from 14 to 17 MeV and charges of 600 to 1300 pC, considering electrons with energies above 8 MeV. Preliminary estimates of molybdenum-99 yields for the optimal beams were obtained using their phase space data from PIC simulations as radiation sources in Monte Carlo simulations irradiating a tantalum-molybdenum target.
Electronic stopping cross sections of tungsten to swift ions and comparisons with models
2025 - SILVA, TIAGO F.; SILVA, ARILSON; RODRIGUES, CLEBER L.; ADDED, NEMITALA; TABACNIKS, MANFREDO H.; MATIAS, FLAVIO; YORIYAZ, HELIO; SHORTO, JULIAN M.B.
Accurate stopping power data for tungsten is crucial for ion beam analysis (IBA) techniques applied to fusion-related materials. In this work, we present new experimental measurements of the stopping power of tungsten for protons and alpha particles, addressing key gaps in fundamental databases. Our results provide a densely spaced dataset, refining the practical uncertainty limits to approximately 1.8% for protons and 2.0% for alpha particles. We critically compare our findings with semi-empirical and theoretical models, evaluating their performance in describing the stopping power of tungsten for light projectiles. By improving the accuracy and reliability of stopping power data, we contribute to the enhancement of the applicability of ion-beam methods for characterizing tungsten in fusion-related research. These findings contribute to the refinement of semi-empirical models and support the ongoing efforts to develop more precise theoretical frameworks for ion-solid interactions in high-Z materials.
Effect of heat treatment and gamma irradiation on TL emission sensitivity of blue quartz crystal
2025 - CARRERA, BETZABEL N.S.; CANO, NILO F.; CRUZ, FELIX V.S.; PILCO, EDWIN J.; RAO, T.K.G.; BENAVENTE, J.F.; CHUBACI, JOSE F.D.
The combined effect of heat treatment and irradiation on the thermoluminescent response of natural blue quartz was studied. Samples were subjected to different heat treatment temperatures, pre-dose doses, and thermal activation temperatures to sensitize the Thermoluminescence (TL) response of blue quartz. Blue quartz pellets produced by sintering at 1200 °C were sensitized with a combination of different pre-doses and thermal activation temperatures. It was found that the maximum TL intensity occurred for a pre-dose of 500 Gy and a thermal activation temperature of 550 °C, resulting in a dosimetric peak with a TL signal 150 times more intense than the initial one. The kinetic parameters of the TL glow curve of the sensitized pellets were analyzed by the methods of different heating rates, Tm-Tstop, and deconvolution. The dosimetric properties of the sensitized blue quartz pellets were also evaluated using the 220 °C TL peak.
Arsenic bioaccumulation in ready-to-eat oysters can contribute to the selection of WHO critical priority enterobacterales displaying a virulent behavior
2025 - VASQUEZ-PONCE, FELIPE; GAMBOA-ACUNA, NICOLAS; OLIVEIRA, ALINE P. de; BECERRA, JOHANA; PARIONA, JESUS G.M.; LIMA, LEON de O.; ELIAS, ALINE de C.; LUZ, MACIEL S.; RIBAS, MATEUS R.; ROCHA, GUSTAVO; ESPOSITO, FERNANDA; MUNOZ, PATRICIO; MOREIRA, EDSON G.; NOMURA, CASSIANA S.; SINCERO, THAIS; BARBIERI, EDISON; LINCOPAN, NILTON
The bioaccumulation of arsenic (As) in shellfish poses a serious threat to human health, whereas the occurrence of antimicrobial-resistant bacteria in seafood raises food safety concerns. We investigated the occurrence and genomic background of WHO critical-priority Enterobacterales in ready-to-eat (RTE) oysters, and their association with As bioaccumulation. RTE oysters collected between September 2022 and March 2023, in five Brazilian markets, were analyzed. In brief, oyster tissue samples were aseptically removed and processed for isolation and identification of carbapenem- and/or third-generation cephalosporin-resistant Enterobacterales, using MALDI-TOF (Bruker) and disk diffusion methods. Heavy metal tolerance was evaluated by microdilution assays. Quantification of As, Hg, Cu, Co, Ag and Pb was performed by inductively coupled plasma optical emission spectrometry and atomic absorption spectrometry. Enterobacterales were sequenced by Illumina NextSeq, and virulence was evaluated using the Galleria mellonella infection model. Statistical analysis was made with Phyton. Total As concentrations in RTE oysters ranged from 0.44 to 1.95 mg/kg. Five As-tolerant (MIC≥1024 μg/mL) and multidrug-resistant Enterobacterales producing extended-spectrum beta-lactamases (ESBLs) were identified. WGS confirmed the ars operon among international clones of Klebsiella pneumoniae (ST307) coproducing CTX-M-15 and SHV-28, Escherichia coli (ST38 and ST23) producing CTX-M-15 and CTX-M-55, and K. quasipneumoniae (ST526) producing SHV-5 ESBLs. Citrobacter telavivensis producing CTX-M-15 in seafood is reported for the first time. E. coli ST38 and ST23 exhibited highly virulent behavior and phylogenomic relationships with human lineages. The occurrence of WHO priority pathogens and As bioaccumulation in oysters is a public health issue that requires surveillance and appropriate management strategies.
Conversion of methane into value-added products in catalytic-assisted solid oxide fuel cell
2025 - VILELA, VANESSA B.; FOUNET-FAYARD, FRANCK; STEIL, MARLU; THYSSEN, VIVIAN; FLORIO, DANIEL Z. de; FERLAUTO, ANDRE S.; FONSECA, FABIO C.
Separating catalytic and electrochemical reactions at the fuel electrode of the direct methane solid oxide fuel cell (SOFC) produces syngas and C2 products (ethane and ethylene), while cogenerating electricity. A SOFC-compatible La0.5Ce0.5O2-δ catalyst is first validated for the oxidative coupling of methane (OCM) reactions with O2 and H2O oxidizing agents in a fixed-bed reactor. It is then applied as a catalytic layer on the current collector of a standard nickel/yttria-stabilized zirconia (Ni/YSZ) anode. A systematic study of operating parameters such as temperature, fuel concentration, flow rate, and applied current reveals a maximum C2 production rate of 1.5 mmol min−1 cm−2 and over 50 % selectivity for syngas (H2/CO ∼ 1). Experimental results, supported by thermodynamic data, indicate that steam generated by electrochemical hydrogen oxidation promotes both steam reforming and methane oxidative coupling within the catalytic layer, ensuring stable SOFC operation. This innovative fuel electrode configuration, featuring an OCM-active layer, enables efficient catalytic-assisted conversion of methane into value-added products within a SOFC.
Advancing direct ethanol metal supported fuel cells with catalytic layer
2025 - CARVALHO, S.G.M.; TABUTI, F.N.; SANTIAGO, E.I.; ABE, R.; GUIMARAES, R.M.; MIURA, Y.; FUKUYAMA, Y.; FONSECA, F.C.
Fuel cells are efficient power sources to play a role in the urgent energy transition. Direct ethanol fuel cells may boost the application of solid oxide fuel cell because ethanol is an efficient, sustainable, and readily available fuel. Metal supported solid oxide fuel cells provide the necessary mechanical properties to allow complex applications such as vehicles. Thus, the combination of a renewable fuel and a robust fuel cell may be a perfect combination for widespread decarbonization of transportation, facilitated by an economic viable and energetic efficient liquid fuel. However, several challenges remain to prolong the durability of such devices running on ethanol. We report on the significant improvement of the metal supported fuel cell stability operating at relatively low temperature (700 °C) with ethanol by adding a porous active catalytic layer with controlled microstructure using processing parameters compatible with the metal-supported solid oxide fuel cell technology.
Gamma-irradiated PVP-PVAL clay-hydrogels
2025 - ALMEIDA, L.D.; GONCALVES, K.O.; PARRA, V.; PARRA, D.F.
The pursuit of biomaterials and medicines dosed at therapeutic levels has become increasingly intensive over time. There is a growing need for materials that respond more efficiently to the demands of daily use. Hydrogels have the potential to meet this demand due to the specific characteristics of their reagents and synthesis methods. This article investigates the influence of Laponite RD (Lap), a clay material, as a crosslinking mediator in the gamma radiation synthesis of PVP/PVAL hydrogels. The central question addressed is how Lap, which possesses dual properties as both a drug carrier and a crosslinking mediator, can enhance both functionalities without antagonistic effects. The data presented in this study demonstrate the interaction between polymers and clay, as confirmed by FTIR, XRD, and TG/DSC analyses. Swelling and gel fraction tests revealed that the polymer network is also altered by the presence of Lap. Mechanical resistance tests indicated that the Young's modulus varies with increasing Laponite concentration, in addition to enhancing the elasticity of the hydrogel. However, despite these findings, all analytical techniques suggest that there may be a limit to the polymer–clay interaction. Furthermore, the hydrogels did not exhibit an inhibition halo against E. coli bacteria, but positive optical density results indicated bacterial inhibition. Additionally, this research contributes to the future development of a matrix suitable for clay-drug systems, in hydrogel form, for drug delivery systems in pharmaceutical applications.
Enhancing cementoenamel junction (CEJ) imaging using gold nanorods in optical coherence tomography (OCT)
2025 - SILVA, CAROLINA P. da; LIMA, MARIA H. da C.T. de; JUNIOR SILVA, MANOEL B. da; CAVALCANTI, MARCELA R.N.; ANDRADE, AUDREY N. de; DAS, AVISHEK; PRAMANIK, MANOJIT; SILVA, DANIELA de F.T. da; ZEZELL, DENISE M.; GOMES, ANDERSON S.L.; LOPES, DANIELA S.
This study investigates the innovative use of gold nanorods (AuNRs) as optical clearing agents to enhance detailed visualization of the cementoenamel junction (CEJ) in optical coherence tomography (OCT), a non-invasive imaging modality. Eighty extracted teeth were carefully examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to classify CEJ types. Imaging was performed under four distinct contrast conditions: air (G1), glycerol (G2), AuNRs (G3), and AuNRs combined with glycerol (G4). Statistical analysis (ANOVA and Tukey’s test, p < 0.05) showed that AuNRs, especially in G4, significantly enhanced CEJ visualization by reducing scattering and improving image contrast. Specifically, for the enamel region, the AuNRs-containing groups (G3 and G4) showed the lowest attenuation coefficients (0.0011100 and 0.0010435, respectively), compared to groups 2 and 1. The same was observed in the CEJ region: the AuNRs-containing groups (G3 and G4) showed the lowest attenuation coefficients (0.0010830 and 0.0009060, respectively). Attenuation analysis indicated greater absorption in the enamel and CEJ regions with AuNRs and glycerol, while cementum remained unaffected. The preservation of cementum suggests that the combination of AuNRs and glycerol enhanced OCT imaging without compromising tissue integrity. These results highlight the potential of AuNRs to further enhance OCT-based CEJ imaging for detecting clinically significant “gaps,” thereby advancing its role as a reliable diagnostic tool in dentistry.
Proteolytic activity of secreted proteases from pathogenic leptospires and effects on phagocytosis by murine macrophages
2025 - AMAMURA, THAIS A.; COURROL, DANIELLA dos S.; BARBOSA, ANGELA S.; SILVA JUNIOR, ILDEFONSO A.; SILVA, TIAGO F. da; MIDON, LEONARDO M.; CRUZ, MARIO C.; HEINEMANN, MARCOS B.; CHURA CHAMBI, ROSA M.; MORGANTI, LIGIA; ISAAC, LOURDES
Leptospirosis is a zoonosis caused by spirochete Leptospira. Pathogenic leptospires evade the Complement System, enabling their survival upon contact with normal human serum in vitro. In a previous study, we demonstrated that proteases secreted by pathogenic leptospires cleave several Complement proteins, including C3 and the opsonins C3b and iC3b. We hypothesize that these Leptospira proteases, such as thermolysin and leptolysin, may decrease the phagocytic activity of murine peritoneal macrophages. We observed decreased amounts of CR3 and CR4 using flow cytometry when these cells were treated with supernatant from the culture of pathogenic leptospires (SPL) for 24 h. Through confocal microscopy, we observed a reduction in TLR2, CD11b, and CD206 (mannose receptor) levels when these cells were treated with SPL or recombinant thermolysin for 24 h. Furthermore, opsonins such as C3b/iC3b deposited on the surface of pathogenic leptospires were clearly degraded in the presence of recombinant thermolysin or recombinant leptolysin. Consequently, when opsonized bacteria and macrophages were previously incubated with these proteases, phagocytic activity was diminished. These observations lead us to suggest that proteases secreted by pathogenic leptospires could degrade opsonins present in normal serum or deposited on the bacterial membrane, as well as cleave or inhibit macrophage surface molecules. Therefore, these proteases could interfere with the recognition and internalization by murine macrophages, favoring the spread of leptospires in the host.
One strain many compounds approach for anti-trypanosoma cruzi compounds
2025 - ANDRADE, BEATRIZ A.; SANTOS, AUGUSTO L. dos; FERREIRA, DAYANA A.S.; ABIUZI, MARIANA B.; VIEIRA, DANIEL P.; GONCALVES, MARINA M.; LAGO, JOAO H. G.; SARTORELLI, PATRICIA; TEMPONE, ANDRE G.
Neglected tropical diseases as Chagas disease (CD) affect more than eight million people, mainly in the Americas, causing fatal cardiovascular outcomes. Relying on two old, toxic, and low efficacy drugs for treatment, there is an urgent need for new candidates. Comprising a high chemodiversity, marine bacteria are a rich source of small molecules with potential against human pathogens. Cultivation-based strategies of bacteria, such as the one strain many compounds (OSMAC) approach, have proven to be a simple and promising tool for drug discovery, with the ability to stimulate the expression of cryptic genes in microorganisms. In this study, using the OSMAC, we evaluated the potential of the marine bacteria Metabacillus indicus to produce anti-Trypanosoma cruzi compounds with higher potency. The M. indicus was cultivated under different conditions, subdivided into four groups, as nutritional, physical, biological, and chemical alterations. For comparisons, the extract obtained from the bacteria in Marine Broth (static) at 25 °C was used as a control and resulted in an EC50 value of 28 μg/mL against the trypomastigotes. The physical alterations proved to be the most effective approach to improve the potency of M. indicus metabolites, resulting in EC50 values between 3 and 26 μg/mL. The cultivation in Marine Agar potentiated the antitrypanosomal metabolites by 8.4-fold. When exposed to cobalt-60 γ radiation (0.5 kGy), the bacteria produced metabolites with 2-fold higher antitrypanosomal potency. The nutritional alterations resulted in potent metabolites, with EC50 values between 11 and 18 μg/mL, while biological alterations resulted in EC50 values between 11 and 28 μg/mL. Addition of T. cruzi and Leishmania infantum antigens and co-cultivation with Acinetobacter baumannii, enhanced by 2-fold the potency. Chemical elicitors such as DMSO and EtOH demonstrated no improvements for M. indicus cultivation. The chemical profile of M. indicus was analyzed using NMR and UHPLC-ESI-HR-MS/MS and processed using the GNPS platform, which led to the annotation of nucleosides, dipeptides, steroids, and fatty acid derivatives. These findings confirmed that the OSMAC approach yielded not only distinct antitrypanosomal activities but also distinct metabolomic profiles in M. indicus that could be exploited for drug discovery studies for Chagas disease.
Design and construction of a high-efficiency linearly polarized Nd:YAG laser at 1064 nm using diode side-pumping in a coupled ring-linear cavity
2025 - DANESHVARPOUR, MARYAM; SABAEIAN, MOHAMMAD; BERECZKI, ALLAN
This study presents the design, modelling, and implementation of a high-efficiency, linearly polarized Nd:YAG laser operating at 1064 nm, based on what we believe to be a novel coupled ring–linear cavity configuration with diode side-pumping. To overcome the challenges of unpolarized emission and thermal lensing in side-pumped solid-state lasers, a side cavity containing a Brewster window was integrated, enabling quasi-unidirectional operation and enhanced polarization purity. A 50% increase in output power was achieved compared to the conventional ring cavity, while the polarization conversion efficiency reached up to 82%. The thermal lens focal length was characterized both experimentally and via LASCAD simulation, showing close agreement (e.g., 760 mm vs. 802 mm at 13 A). Comprehensive stability analysis using the ABCD matrix method and LASCAD simulations guided the optimization of cavity geometry, minimizing astigmatism and ensuring mode stability. Experimental validation demonstrated near-diffraction-limited beam quality with M2 ≈ 1.2, measured according to ISO 11146-1:2005. In addition, optimal positioning of the nonlinear crystal (99 mm from M4) was identified for efficient second harmonic generation. This coupled cavity strategy offers a robust and scalable solution for generating high-power, polarized beams in solid-state lasers, particularly benefiting applications in nonlinear optics, frequency conversion, and single-frequency operation.
Effects of e-beam irradiation on the chemical, thermal, and mechanical properties of polyamide-6, polyamide-6.6, and polypropylene used in conveyor belt rollers
2025 - ARQUINTO, JULIANA; HARADA, JULIO; CASTRO, DIONE P. de; SILVA, LEONARDO G. de A. e
In this study, polyamide 6 (PA 6), polyamide 6.6 (PA 6.6), and polypropylene (PP) polymers were irradiated with an e-beam (EB) (100 and 200 kGy doses, 100 kGy.s-1 dose rate, at room temperature) to evaluate the effects on radiochemical crosslinking. Mechanical analyses (tensile, flexural, and tribological tests), thermal characterizations (TGA, DSC, and glow wire test), and FTIR spectroscopy were performed. Results demonstrated that PA 6.6 irradiated at 200 kGy exhibited a 6.8% increase in tensile strength at break, being the only material showing improvement in yield point. All samples displayed reduced elongation after irradiation. In flexural resistance tests, both irradiated PA 6 and PA 6.6 showed enhanced properties, while in tribological evaluations, only PA 6.6 (100 kGy) presented a reduced friction coefficient. Thermal analyses revealed that irradiated PA 6.6 showed increased onset degradation temperature, while all polymers exhibited decreased melting temperature. The crystallinity percentage increased in both irradiated PA 6.6 and PP, and only PA 6.6 (200 kGy) resisted all temperature levels in the glow wire test. It was concluded that PA 6.6 demonstrated superior post-irradiation performance, showing more enhanced properties compared to PA 6 and PP. © 2025 Universidade Federal de Sao Carlos.

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