Centro de Tecnologia Mineral

Background Suicide is a leading cause of death worldwide, yet its prediction remains a challenge. This difficulty arises not only because suicidal behavior is a rare event in the general population, leading to significant class imbalance in datasets, but also due to its complex, multi-causal nature involving a non-linear interplay of sociodemographic and clinical factors. Furthermore, while the majority of suicides occur in middle-income countries, there is a lack of predictive models tailored to these specific social contexts. This study evaluates machine learning strategies in an enriched clinical setting: a pediatric psychiatric emergency center in Brazil. Methods We analyzed a comprehensive database of 2,365 youth seeking emergency care. We benchmarked three machine learning algorithms, namely Logistic Regression, Random Forest, and XGBoost, to predict three outcomes: self-harm, suicidal ideation, and suicide attempts. To address class imbalance, we applied oversampling techniques to the training data. We also used SHapley Additive exPlanations (SHAP) values to quantify each feature's contribution to the predictions. Findings and interpretation In this setting, suicide-related behaviors represented 28.7% of the clinical demand. The Random Forest model combined with oversampling was the most effective strategy, achieving sensitivities of 78.04% for suicidal ideation, 71.18% for suicide attempts, and 69.37% for self-harm. Specificity remained consistently above 75%. SHAP value analysis revealed that social determinants were critical predictors, highlighting that social conditions in middle-income populations introduce unique variables that significantly influence suicidal risk. While accuracy for suicide attempts remained a challenge, SHAP provided clear clinical insights into the drivers of risk. Conclusions Machine learning, specifically Random Forest models together with oversampling and SHAP, demonstrates strong potential for identifying suicidal risk in pediatric emergency settings. By integrating clinical data with social determinants, these models provide a transparent and scalable strategy for early identification in regions with limited specialized psychiatric resources.

<title>Abstract</title> The use of bauxite ores with high silica content has emerged as a critical aspect in meeting the growing demands of the aluminum industry. However, the presence of reactive silica, predominantly occurring as kaolinite, presents major challenges in processing Brazilian bauxite ores, leading to increased red mud production during alumina refining. This study investigates the beneficiation of bauxite from Pará, Brazil, with emphasis on the selective removal of reactive silica through grinding and washing techniques. A thorough physicochemical characterization was conducted employing a suite of characterization techniques, including wet chemical analysis, XRD, FTIR, XRF, SEM-EDS, thermal analysis (TGA-DTG), and zeta potential measurements. The results revealed kaolinite as the dominant silicate phase, closely associated with gibbsite particles. The beneficiation process reduced reactive silica content from 10.4 wt% to 5.3 wt%, with granulometric analysis confirming its preferential concentration in finer fractions. Zeta potential measurements indicated positive surface charges across a wide pH range (2.0 to 10.5), suggesting favorable electrostatic interactions between kaolinite and gibbsite. These findings provide insights into the behavior of silicate minerals in bauxite and support the development of silica-targeted beneficiation strategies to improve alumina production efficiency and reduce environmental impact.

Alphainterferons are cytokines that became famous in the treatment of certain infections and tumors due to their antiviral, antiproliferative, and immunomodulatory activities. These small proteins have been successfully manufactured in transformed Esc

We fabricated oxygen-deficient ZnO thin films on sapphire substrates via pulsed laser deposition and precisely patterned them into 70 nm wide stripes using photolithography and focused ion beam nanomachining. This configuration allowed us to perform a detailed quantitative analysis of the weak localization (WL) anisotropy effects in a low-dimensional system. By aligning the magnetic field either parallel or perpendicular to the stripe plane in a maximum Lorentz force configuration, we uncovered a pronounced anisotropic magnetoresistance at low temperatures. Angle-dependent magnetoresistance measurements further elucidated this anisotropy, which is well described by the combination of Altshuler-Aronov’s 2D WL theory and the two-band model for positive magnetoresistance.

Electrooxidation has proven to be an efficient technique for treating effluents containing ammoniacal nitrogen and organic matter. In the present study, electrooxidation trials were conducted with an ammoniacal effluent generated at a fertilizer depot, containing 0.24 mol L−1 of N-NH3 and 0.90 mol L−1 of Cl−. The Ti/RuO2 electrodes were used in a stirred batch electrochemical reactor. The results obtained, employing a current density of 60 mA cm−2, showed degradation rates of 99.9% for ammoniacal nitrogen and 75.6% for organic matter. Accelerated anode degradation tests with the same solution, maintaining a constant current density of 1,000 mA cm−2, indicated that after 300 h, a partial dissolution of the RuO2 coating was observed, along with the formation of a passive TiO2 film and an increase of approximately 24% of the initial anodic potential value. Considering a working current density of 60 mA cm−2, the estimated service life of the Ti/RuO2 anode is 6 years.

Most current cooling systems are based on mechanical compression and expansion processes that use halocarbons as the primary refrigerants. These refrigerants contribute to global warming, leading the scientific community to research and develop eco-friendly technologies. One of these alternative technologies is based on the barocaloric effect. Promising materials for barocaloric applications are categorized into different classes, including polymers, intermetallic compounds, plastic crystals, and n-alkanes. In this study, we reported large to colossal values of the barocaloric effect for a new class of promising material: fatty acids. The myristic, palmitic, and stearic acids were investigated by direct measurements. The reversibility of the phenomena was investigated, both near and far from the liquid–solid phase transition. Furthermore, the fatty acids reached large values of the barocaloric effect in solid–solid processes and colossal values in liquid–solid transitions. Thus, it results in a broad range of usable temperatures.

Abstract Current methods for assessing the remaining fatigue life of dented pipelines may lead to unnecessary maintenance interruptions and high-cost procedures. This paper studies the impact of dents on the fatigue life of pipelines when subjected to cyclic internal pressure using finite element numerical models. A key contribution of this work is the explicit incorporation of service (pressurization) and shutdown (depressurization) conditions into the fatigue assessment, offering a more realistic and comprehensive understanding of pipeline structural behavior. The study examines the behavior of the dented pipe section during spring-back and re-rounding under internal pressure. The results indicate that, for the same initial dent depth, the spring-back coefficient (ratio of the dent depth after spring-back to the initial dent depth) increases with a reduction in the slenderness of the pipe (diameter to thickness ratio) and decreases as the yield strength of the pipe increases. Stress concentration factors (SCFs) in dented pipes were evaluated from numerical simulations for varying pipe dimensions and materials and different indenter shapes (spherical and cylindrical) and dent depths. Based on the obtained SCFs and considering a suitable S-N curve, fatigue analyses were conducted on 240 dented pipe models, and the results indicated a significant decrease in fatigue life with increasing remaining dent depth, characterized after the full process of spring-back followed by re-rounding under internal pressure and depressurization, for all slenderness ratios and indenter shapes. The cylindrical indenter (placed perpendicularly to the pipe axis) generated dents with superior fatigue life compared to those produced by the spherical indenter due to lower stress concentration factors resulting from the cylindrical indenter, at the same dent depth. This paper provides insight into the structural integrity of dented pipelines and can assist in predicting the remaining fatigue life of these structures after experiencing an accidental collision event.

Characteristics associated with seasonality in Southern Brazil impose numerous restrictions on the growth of native species, and therefore, morphophysiological adaptations are necessary for the maintenance of metabolism. Identifying these responses allows for a more accurate indication of the suitability of species for locations with extreme climatic and soil conditions. The objective of this study was to evaluate the influence of shading levels (SL) and climatic seasonality on the morphophysiology of young Myrcianthes pungens (O. Berg) D. Legrand and Cupania vernalis Cambess plants in a subtropical region. Species of significant importance for restoration were subjected to four levels of shading (SL0, SL18, SL50, and SL70) and evaluated during contrasting seasons of temperature and growth (winter and spring). In winter, both showed an increase in specific leaf area and variation in the amount of chlorophyll a and b, mainly under SL50 and SL70, which optimized photosynthesis under reduced light, sunlight hours and solar radiation. The increase in radiation and air temperature in spring denoted greater maximum assimilation of CO2 in plants under SL18, SL50 and SL70, which from the analysis of principal components can be justified by the characteristics of the microclimate generated in these environments. Therefore, to optimize growth, M. pungens and C. vernalis must be planted under 50% shading because of morphophysiological adaptations in plants during seasons with subtropical climatic characteristics.

Climate change is a serious global problem. CO2 is of paramount importance in mitigating this environmental problem. Understanding the interaction of CO2 with functionalized carbon structures is essential for designing new materials to aid in efficiently capturing CO2. In this work, the interaction between carbon dioxide (CO2) and coronene models, simulating graphene and the asphaltene moiety, was studied through DFT (CAM-B3LYP-D3) and DLPNO-CCSD(T) methods to investigate the effect of nitrogen doping in two arrangements. Aromaticity, electronic, and topological properties were evaluated using HOMA, HOMO-LUMO gap, QTAIM, and NCI methods. The results show that the adsorption of CO2 in the coronene molecule is dependent on the position of the heteroatom and governed by noncovalent interactions, such as van der Waals and hydrogen bonds. The CO2/N-coronene complex with pyridinic-N is stabilized due to two unconventional hydrogen bonds parallel to the aromatic π system. We hope that the present results can help the synthesis of inhibitors of asphaltene precipitation and better systems for CO2 capture.