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FTIR spectroscopy analysis of bound water in dried saliva samples
2025 - FERREIRA, MARIA C.C.; MAGALHAES, VITORYA C.P. de; MORAIS, THAYNA M. de L.; PERALTA, FELIPE; CASTRO, PEDRO A.A.; ZEZELL, DENISE M.; NOGUEIRA, MARCELO S.; CARVALHO, LUIS F.C.S.
Background: According to the WHO, oral cancer is the thirteenth most common cancer worldwide, with tobacco use being one of the primary causes of oral cancer. This study aimed to characterize and differentiate the saliva and bound water using FTIR spectroscopy in smoking and non-smoking individuals. Materials and Methods: This prospective observational study analyzed dried saliva samples from control, smoking, and occasional smoking groups using an attenuated total reflectance Fourier Transform Infrared (ATR-FTIR) spectrometer. The high wavenumber spectral region of 2800–3600 cm-¹ was selected for analysis. Results: The results indicate that standard variance normalization (SNV) reduced intragroup variability and highlighted differences in smokers’ spectra within the 3250–3500 cm-¹ region, associated with the absorption of water bound to saliva molecules. Cubic SVM models using SNV spectra demonstrated higher classification accuracy between groups, achieving 15.6% greater sensitivity and 1.3% lower specificity compared to models based on the second-order derivative. RUSBoosted Trees addressed data imbalances, enhancing both sensitivity and specificity. The study suggests that spectral changes may reflect salivary biochemistry linked to smoking and potentially to oral cancer risk. Conclusions: We conclude that differentiation between normal individuals and smokers can be achieved using high wavenumber FTIR spectral analysis. Additionally, we demonstrate the relationship between bound water molecules and salivary biomolecules in control, smoking, and occasional smoking groups. This technique has potential applications in elucidating OH vibrations within biological systems.
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Microplastic deposits prediction on urban sandy beaches
2025 - FERREIRA, ANDERSON T. da S.; OLIVEIRA, REGINA C. de; SIEGLE, EDUARDO; RIBEIRO, MARIA C.H.; ESTEVES, LUCIANA S.; KUZNETSOVA, MARIA; DIPOLD, JESSICA; FREITAS, ANDERSON Z. de; WETTER, NIKLAUS U.
This study focuses on the deposition of microplastics (MPs) on urban beaches along the central São Paulo coastline, utilizing advanced methodologies such as remote sensing, GNSS altimetric surveys, µ-Raman spectroscopy, and machine learning (ML) models. MP concentrations ranged from 6 to 35 MPs/m2, with the highest densities observed near the Port of Santos, attributed to industrial and port activities. The predominant MP types identified were foams (48.7%), fragments (27.7%), and pellets (23.2%), while fibers were rare (0.4%). Beach slope and orientation were found to facilitate the concentration of MP deposition, particularly for foams and pellets. The study’s ML models showed high predictive accuracy, with Random Forest and Gradient Boosting performing exceptionally well for specific MP categories (pellet, fragment, fiber, foam, and film). Polymer characterization revealed the prevalence of polyethylene, polypropylene, and polystyrene, reflecting sources such as disposable packaging and industrial raw materials. The findings emphasize the need for improved waste management and targeted urban beach cleanups, which currently fail to address smaller MPs effectively. This research highlights the critical role of combining in situ data with predictive models to understand MP dynamics in coastal environments. It provides actionable insights for mitigation strategies and contributes to global efforts aligned with the Sustainable Development Goals, particularly SDG 14, aimed at conserving marine ecosystems and reducing pollution.
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High-efficiency [18F]fluoride pre-concentration using a laser-micromachined anion-exchange micro-cartridge
2025 - GOMES, ANTONIO A.; NARIO, ARIAN P.; LAPOLLI, ANDRE L.; SAMAD, RICARDO E.; BERNARDES, EMERSON B.; ROSSI, WAGNER de
Background: The use of radiopharmaceuticals labelled with fluorine-18 in non-invasive imaging, particularly in Positron Emission Tomography (PET), increased significantly during the last decade. However, traditional nucleophilic fluorination synthesis methods in most cases require azeotropic drying steps, leading to loss of activity and increased synthesis time. Microfluidic devices offer improvements with shorter reaction times, higher elution efficiency, and reduced reagent quantities. Results: We developed a novel micro-cartridge for [18F]fluoride trapping and elution, etched in borosilicate optical glass (BK7) using ultrashort laser pulse machining. The micro-cartridge has a bead volume of 17 µL and a maximum capacity of 8.5 mg for anion exchange resin. The micro-cartridge, without the need for QMA preconditioning, exhibited an overall trapping efficiency and recovery efficiency (RE) of (94.09 ± 0.12)% using an activity exceeding 123 GBq of [18F]fluoride. This RE was obtained using 100 µL of a standard solution of anhydrous acetonitrile with Kryptofix 2.2.2, containing only 5 µL of water and 5.4 µmol of K2CO3 for [18F]fluoride elution. This solution was employed directly in the radiosynthesis of [18F]fluoromisonidazole ([18F]FMISO), resulting in a 100% radiochemical conversion (RCC) to THP-protected [18F]FMISO within 10 min at 110 °C. Conclusions: The developed micro-cartridge provides a novel tool for integrating microfluidic chips into conventional cassettes, facilitating more efficient radiopharmaceutical preparation.
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Laser cladding of iron aluminide coatings for surface protection in soderberg electrolytic cells
2025 - GOMES, ALEX F.; SANTOS, HENRIQUE C. dos; SENO, ROBERTO; FRANCISCO, ADRIANO; LIMA, NELSON B. de; ALMEIDA, GISELE F.C.; REIS, LUIS; MASSI, MARCOS; COUTO, ANTONIO A.
In this work, iron aluminide coatings (FeAl and Fe3Al) were developed on carbon steel substrates using the laser cladding process with mixtures of elemental iron and aluminum powders, aiming at protecting anodic pins in Soderberg electrolytic cells against oxidation and corrosion at high temperatures. These components operate under atmospheres rich in CO2, alumina dust, and intense thermal cycles. The influence of processing parameters on the microstructure, phase formation, and mechanical properties of the coatings was investigated. X-ray diffraction confirmed the formation of the FeAl phase with a B2 ordered structure, while the expected D03 ordering in Fe3Al was not detected, likely due to crystallographic texture effects. Microstructural analysis, optical and scanning electron microscopy, revealed dense coatings with good metallurgical bonding to the substrate and low porosity, being the conditions of 3.5 kW with 3 mm/s resulted in the best quality coatings. The FeAl coatings exhibited microhardness values of approximately 400 HV, whereas the Fe3Al coatings showed values around 350 HV, indicating a significant improvement compared to the carbon steel substrate. These results demonstrate that laser cladding is an effective technique for producing iron aluminide coatings with potential application for corrosion and wear protection of anodic pins in Soderberg electrolytic cells.