In this work, the local electrochemical activity of the zones coupled by Friction Stir Welding (FSW) of an Al-Cu-Li alloy was studied and the results were correlated to the microstructural characteristics of each zone. Electrochemical studies were carried out in the zones affected by welding using cyclic voltammetry (CV) and scanning electrochemical techniques (namely, SECM - Scanning Electrochemical Microscopy and LEIS - Local electrochemical impedance spectroscopy). The results showed that the welding joint (WJ) is predominantly cathodic relatively to the heat affected zones (HAZ). The HAZ was always anodic and showed the highest electrochemical activities among the tested ones. The high electrochemical activity of the HAZ was associated with the effect of galvanic coupling between the cathodic region (WJ) and the anodic region (HAZ). In addition, the advancing side (AS) presented increased electrochemical activity compared to the retreating one (RS).

In this study, the corrosion mechanism of an Al-Cu-Li alloy manufactured by two different treatment routes (T3 and T851) was evaluated by immersion and electrochemical tests in solutions containing chloride ions (Cl-). For both alloys, the formation of cavities on the surface was associated with micrometer-sized intermetallics (IM’s), however, in addition to this attack, the alloy submitted to T851 treatment also presented an attack called severe localized corrosion (SLC), caused by the preferential attack to the nanometric T1 (Al2CuLi) phase. The electrochemical concepts involved in these two types of attacks were discussed. During the IM’s corrosive process, whereas the O2 reduction occurred over the IM’s, the Al dissolution is favored around the particle, forming trenching and cavities (with 2 and 6 μm of depth). On the other hand, the mechanism associated with the SLC is related to the formation of a differential aeration cell followed by the evolution of H2, with greater depth of attack penetration (8 and 35 μm). Additionally, by the use of the Scanning Vibrating Electrode Technique (SVET), it was concluded that the higher anodic currents observed for the T851 temper were related to the relation between the anodic area (Aa) and the cathodic area (Ac).

Abstract Introduction: patients with COVID-19 undergo changes in leukocyte count, respiratory disorders, and an increase in inflammatory substances. To improve the inflammatory condition, some nutrients can be used, including arginine, omega-3 fatty acids and nucleotides. This study aims to evaluate how oral immunonutrient supplements affects serum C-reactive protein (CRP) levels and lymphocyte count in patients with COVID-19. Methods: in this double-blind clinical trial, we randomized 43 adult patients with COVID-19 to receive a standard high-protein normocaloric supplement (control) or an immunonutrient-enriched supplement (experiment) for 7 days. The primary outcome was to evaluate changes in total lymphocyte count and serum level of CRP. The assessment of risk and nutritional status of these patients was also performed. Results: forty-three patients with mean age of 41.5 (± 1.8) years were followed up, 39.5 % of them women. The mean body mass index was 27.6 (± 0.8) kg/m² and 58.1 % had low nutritional risk. In the experiment group, there was a CRP reduction of 23.6 (± 7.5) mg/L, while in the control branch the decrease was 14.8 (± 12.1) mg/L (p = 0.002). There was an increase in lymphocytes in the experiment group (+367.5 ± 401.8 cells/mm³) and a reduction in the control group (-282.8 ± 327.8 cells/mm³), although there was no statistical significance (p = 0.369). Relative risk (RR) of treatment in reducing CRP by 30 % or more was 4.45 (p < 0.001; 95 % CI, 1.79-11.07). RR in increasing lymphocyte count by 30 % or more was 1.28 (p = 0.327; 95 % CI, 0.67-2.45). Conclusion: we conclude that immunonutrient supplements seem to reduce CRP levels more than standard high-protein normocaloric supplements.

Resumen Introducción: los pacientes con COVID-19 sufren cambios en el recuento de leucocitos, trastornos respiratorios y aumento de sustancias inflamatorias. Para mejorar la condición inflamatoria se pueden usar algunos nutrientes, como la arginina, los ácidos grasos omega-3 y los nucleótidos. Este estudio tiene como objetivo evaluar cómo los suplementos de inmunonutrientes orales afectan a los niveles séricos de proteína C-reactiva (PCR) y al recuento de linfocitos en pacientes con COVID-19. Métodos: en este ensayo clínico doble ciego, aleatorizamos a 43 pacientes adultos con COVID-19 para recibir un suplemento normocalórico estándar alto en proteínas (control) o un suplemento enriquecido con inmunonutrientes (experimento) durante 7 días. El resultado primario fue evaluar los cambios en el recuento total de linfocitos y el nivel sérico de PCR. También se realizó la evaluación del riesgo y el estado nutricional de estos pacientes. Resultados: cuarenta y tres pacientes con edad media de 41,5 (± 1,8) años fueron seguidos, el 39,5 % de ellos mujeres. El índice de masa corporal medio fue de 27,6 (± 0,8) kg/m² y el 58,1 % tenían bajo riesgo nutricional. En el grupo experimental hubo una reducción de la PCR de 23,6 (± 7,5) mg/L, mientras que en la rama de control la disminución fue de 14,8 (± 12,1) mg/L (p = 0,002). Hubo un aumento de linfocitos en el grupo experimental (+367,5 ± 401,8 células/mm³) y una reducción en el grupo de control (-282,8 ± 327,8 células/mm³), aunque no hubo significación estadística (p = 0,369). El riesgo relativo (RR) del tratamiento para reducir la PCR en un 30 % o más fue de 4,45 (p < 0,001; IC 95 %: 1,79-11,07). El RR en el aumento del recuento de linfocitos en un 30 % o más fue de 1,28 (p = 0,327; IC 95 %: 0,67-2,45). Conclusión: se concluye que los suplementos de inmunonutrientes parecen reducir los niveles de PCR más que los suplementos normocalóricos estándar altos en proteína.

Abstract Aluminum alloys are the state-of-art materials for structural components of aircrafts. As they are susceptible to localized corrosion, this kind of damage can become a major threat for its safe use in aircraft components. Therefore, surface protection of aluminum alloys against corrosion is a core issue in these applications. In this work, an alternative eco-friendly cerium-based surface pretreatment was developed and applied on the AA1230 clad of the AA2024-T3 alloy for corrosion protection. The corrosion resistance evaluation of this modified surface was evaluated by several techniques. The results were compared to chromium based conventional treatments and revealed that the coating layer, composed of spherical nodular nanostructures of cerium, obtained with the proposed eco-friendly treatment, improved the corrosion resistance of the alloy. Moreover, it was comparable to the corrosion behavior of chromate-treated alloy, showing that this treatment is a promising alternative to replace chromate based surface treatments.

THE ANODIZING PROCESS OF ALUMINUM AND ITS ALLOYS: A HISTORICAL AND ELECTROCHEMICAL APPROACH. Al and its alloys are found in several industrial applications. However, like most metals, this material is not immune to corrosion, being necessary to be protected against corrosion. One of the methods most commonly employed to improve the corrosion resistance of Al alloys is the anodizing process, which consists of thickening of the natural oxide (Al2O3) presents in Al through anodic oxidation. The anodizing process is accomplished by immersion of the Al alloy into an acid bath and passing an electric current through it. This process produces two layers: a barrier layer thicker than the natural oxide and a layer with regular arrangement of nanopores (porous layer). This duplex structure forms the anodized layer with a large specific surface area. With the advent of nanotechnology, this layer has been applied in other areas due to its low cost, stability, absence of toxicity, and biocompatibility. In this context, this paper addresses a historical and electrochemical review of the anodizing process of Al and its alloys, presenting the main events that culminated in the development of the current processes and the understanding of the relationship between the chemical reactions and the mechanisms that occur during nucleation and development of the oxide layer.

ABSTRACT OBJECTIVE To investigate whether oral health literacy (OHL) and school context are associated with untreated dental caries on the anterior teeth of adolescents. METHODS A representative cross-sectional study was conducted with 746 students aging 15 to 19 in the city of Campina Grande, Brazil. The guardians answered a questionnaire addressing sociodemographic data and the absence/presence of private health insurance. Two examiners were trained for the diagnosis of dental caries using the Nyvad criteria and the measurement of OHL using the Brazilian Rapid Estimate of Adult Literacy in Dentistry (BREALD-30) (Kappa > 0.80). Contextual aspects of the schools were obtained from the 2017 National School Census. Descriptive statistics were conducted, followed by unadjusted and adjusted robust negative binomial regression for complex samples (p < 0.05). RESULTS The average number of anterior teeth with untreated caries was 0.95 (SD = 1.77). Among individual factors, the male sex (RR = 1.64; 95%CI: 1.24–2.16), inadequate level of OHL (RR = 2.03; 95%CI: 1.13–1.63), marginal level of OHL (RR = 1.87; 95%CI: 1.05–3.33) and not having private health insurance (RR = 1.34; 95%CI: 1.07–1.68) were associated with untreated caries on anterior teeth. Among school contextual factors, the number of students in the classroom (RR = 2.64; 95%CI: 1.78–3.93), number of public oral health services in the district (RR = 0.14; 95%CI: 0.05–0.39) and average income of the district in which the school is located (RR = 0.99; 95%CI: 0.98–0.99) were associated with the outcome. CONCLUSIONS Sociodemographic factors, having private health insurance, OHL, and school context exerted an influence on the occurrence of untreated dental caries on anterior teeth in adolescents aging 15 to 19.

ABSTRACT OBJECTIVE To investigate whether oral health literacy (OHL) and school context are associated with untreated dental caries on the anterior teeth of adolescents. METHODS A representative cross-sectional study was conducted with 746 students aging 15 to 19 in the city of Campina Grande, Brazil. The guardians answered a questionnaire addressing sociodemographic data and the absence/presence of private health insurance. Two examiners were trained for the diagnosis of dental caries using the Nyvad criteria and the measurement of OHL using the Brazilian Rapid Estimate of Adult Literacy in Dentistry (BREALD-30) (Kappa > 0.80). Contextual aspects of the schools were obtained from the 2017 National School Census. Descriptive statistics were conducted, followed by unadjusted and adjusted robust negative binomial regression for complex samples (p < 0.05). RESULTS The average number of anterior teeth with untreated caries was 0.95 (SD = 1.77). Among individual factors, the male sex (RR = 1.64; 95%CI: 1.24–2.16), inadequate level of OHL (RR = 2.03; 95%CI: 1.13–1.63), marginal level of OHL (RR = 1.87; 95%CI: 1.05–3.33) and not having private health insurance (RR = 1.34; 95%CI: 1.07–1.68) were associated with untreated caries on anterior teeth. Among school contextual factors, the number of students in the classroom (RR = 2.64; 95%CI: 1.78–3.93), number of public oral health services in the district (RR = 0.14; 95%CI: 0.05–0.39) and average income of the district in which the school is located (RR = 0.99; 95%CI: 0.98–0.99) were associated with the outcome. CONCLUSIONS Sociodemographic factors, having private health insurance, OHL, and school context exerted an influence on the occurrence of untreated dental caries on anterior teeth in adolescents aging 15 to 19.

Corrosion is still one of the most serious and frequent problems in industries. The phenomena involved in the corrosion mechanism of Al-alloys may be explained by formation of galvanic cells between the metal matrix and heterogeneities, such as precipitates, intermetallic phases leading to potential differences and electrochemical reactions. In the cathodic sites, the main reactions are oxygen reduction reaction, in aerated neutral environments, and hydrogen evolution in acid media. This last type of reaction might also occur in neutral solutions inside pits (anodic region). In this study, the mechanism of hydrogen evolution during corrosion of the 2198-T8 Al-Cu-Li alloy exposed in a chloride solution was investigated. The mechanism was related to the presence of T1 phase (Al2CuLi), which is the main strengthening phase in this material. This phase is highly active and, when exposed to corrosive media, leads to severe localized corrosion (SLC). One of the main characteristics related to SLC is hydrogen gas evolution which was confirmed by gel visualization. In this study, the hydrogen evolution mechanism inside the SLC sites was studied by scanning electrochemical microscopy (SECM).

In the present work, the microstructure, electrochemical behavior and localized corrosion of the AA2198-T851 Al-Cu-Li alloy were studied. The microstructure was correlated with corrosion results obtained by immersion, gel visualization and scanning electrochemical microscopy (SECM) tests. Immersion and gel visualization tests showed high kinetics of corrosion attack during the first hours of immersion. SECM analyzes by means of surface generation/tip collection (SG/TC) mode detected hydrogen evolution generated during spontaneous corrosion from severe localized corrosion (SLC) sites on the metal surface. SECM results revealed sites of intense hydrogen evolution after 2 h of immersion and increased amounts of corrosion products after 4 h of immersion. Hydrogen evolution sites detected by SECM were associated with severe localized corrosion (SLC).

Carmakers must achieve the worldwide targets for lightweight materials, safety and reducing the fuel consumption. The use of press-hardened steel (PHS), in vehicle structures has been contributing with these requirements. This type of steel is widely used for the hot-stamping which consists in heating the steel blank to total austenitization temperature and then transferring it from the furnace into the die tool where the steel is formed and quenched at the same time. PHS is usually protect with metallic coatings in order to avoid both steel oxidation and decarburization. Hot-dip Al-Si coating is currently the main used in this application. However, alternative coatings, like zinc-based, are under investigation. This work aims at evaluating the corrosion resistance of the 22MnB5 grade PHS, electroplated with Zn-Ni, before and after hot stamping, using the scanning vibrating electrode technique (SVET). Results from SVET showed that samples prior to hot stamping, the corrosion mechanism was uniform over the exposed surface, and was mainly related to selective dissolution of zinc from the coating. On the other hand, hot stamped samples showed localized corrosion mechanism with decrease in current with time of immersion due to the formation of corrosion products on the exposed surface.

ABSTRACT Objective: to evaluate comparatively the quality of life of institutionalized and non-institutionalized older adults. Method: observational study conducted in Cuité, Paraíba, with a sample of 40 older adults divided equally between the two categories. Data were collected using the World Health Organization Quality of Life Assessment for Older Adults (WHOQOL-Old) questionnaire and analyzed using descriptive statistics, after approval by the Research Ethics Committee (CAAE 09871412.0.0000.5188). Results: the non-institutionalized older adults showed greater satisfaction in five areas: sensory functioning, autonomy, past, present and future activities, social participation, and intimacy; the only exception being in relation to death and dying. Conclusion: it is necessary to implement effective public policies in favor of better levels of quality of life for the elderly, especially those who are institutionalized, particularly in view of rapid growth in Brazil's elderly population, many of whom live in long-stay institutions.

RESUMEN Objetivo: evaluar comparativamente la calidad de vida de los ancianos institucionalizados y no institucionalizados. Método: estudio observacional realizado en Cuité-PB con muestra constituida por 40 ancianos, subdivididos igualmente para cada categoría. Los datos han sido recolectados utilizando el cuestionario World Health Organization Quality of Life Assessment for Older Adults (WHOQOL-Old) y analizados mediante estadística descriptiva, luego de la aprobación por el Comité de Ética en Investigación, CAAE 09871412.0.0000.5188. Resultados: los ancianos no institucionalizados mostraron una mayor satisfacción en cinco áreas: funcionamiento sensorial, autonomía, actividades pasadas, presentes y futuras, participación social e intimidad, exceptuando el área relacionada a la muerte y el morir. Conclusión: es necesaria la implementación efectiva de políticas públicas que se dirijan a los ancianos, especialmente a los institucionalizados, favoreciendo mejores niveles de calidad de vida, principalmente cuando se considera el rápido crecimiento en el país de la población de ancianos, cuya mayor parte vive en instituciones de larga estadía.

RESUMO Objetivo: avaliar comparativamente a qualidade de vida de idosos institucionalizados e não institucionalizados. Método: estudo observacional realizado em Cuité-PB com amostra constituída por 40 idosos, subdivididos igualmente para cada categoria. Os dados foram coletados utilizando-se o questionário World Health Organization Quality of Life Assessment for Older Adults (WHOQOL-Old) e analisados com base na estatística descritiva, após aprovação do Comitê de Ética em Pesquisa, CAAE 09871412.0.0000.5188. Resultados: os idosos não institucionalizados apresentaram maior satisfação em cinco domínios: funcionamento sensório; autonomia; atividades passadas, presentes e futuras; participação social; e intimidade, com exceção apenas do domínio relacionado à morte e morrer. Conclusão: é necessária a efetiva implementação de políticas públicas direcionadas aos idosos, sobretudo àqueles institucionalizados, favorecendo-lhes melhores níveis de qualidade de vida, principalmente ao considerar o rápido crescimento da população idosa no país, com grande parte vivendo em instituições de longa permanência.

In this study, the corrosion protection provided by films of self-assembled molecules on the AA 2024-T3 aluminum alloy has been evaluated by electrochemical and non electrochemical techniques. The film was obtained by immersion of this alloy samples in a solution of 90 mg L-1 alkane-diphosphonate at 50 °C for 5 minutes. Chromating conversion treatment with trivalent or hexavalent chromium was carried out by immersion of AA 2024-T3 alloy samples for 2 minutes in a 20% (v/v) solution of 650 Chromical TCP (SurTec) at 40 °C. Electrochemical characterization was performed by measurements of the open circuit potential (OCP), potentiodynamic polarization curves (PPC) and electrochemical impedance spectroscopy (EIS) in a solution of 0.5 mol L-1 sodium sulfate buffered with a solution of biphthalate potassium (0.1 mol L-1) and sodium hydroxide (0.1 mol L-1) as the electrolyte. SAM films obtained were analysed by infrared spectroscopy and SAM was found in surface. Surface observation by scanning electron microscopy (SEM) showed that the trivalent chromium layers ere deposited on metal surface. The results show that the surface treatment with self-assembled molecules provides protection against corrosion of the AA 2024-T3 aluminum alloy.

O objetivo deste trabalho é avaliar o efeito da deformação a frio nas propriedades eletrônicas do filme passivo sobre o aço inoxidável austenítico ISO NBR 5832-1 e sua resistência à corrosão por pite. O aço testado foi laminado a frio até ocorrer a redução de espessura do mesmo para 50% da sua espessura inicial. As propriedades eletrônicas do filme passivo sobre este material foram avaliadas e comparadas com a do mesmo material como recebido, ou seja, sem deformação a frio. As propriedades eletrônicas do filme passivo foram caracterizadas pelo método de Mott-Schottky e a resistência à corrosão por pite, por curvas de polarização. O efeito da frequência adotada na análise de Mott-Schottky foi também investigado. Os resultados mostraram que o material deformado apresentou maior concentração de dopantes e maior suscetibilidade à corrosão por pite em comparação ao material sem deformação.

The aim of this work is to evaluate the effect of cold deformation on the electronic properties of the passive film on the ISO NBR 5832-1 austenitic stainless steel and its pitting resistance. The tested stainless steel was cold rolled to 50% of its initial thickness and the electronic properties of the passive film on this material were evaluated and compared with that of the same material as received, that is, without cold deformation. The electronic properties of the passive film were characterized by the Mott-Schottky approach and the pitting resistance by polarization curves. The effect of the frequency adopted in the Mott-Schottky analysis was also investigated. The results showed that the deformed material presented higher concentration of dopants, and higher pitting susceptibility compared with the material without deformation.

As moléculas auto-organizáveis (SAM - Self Assembly Monolayer) são inibidoras de corrosão, devido à capacidade de se organizarem sobre superfícies formando filmes finos. A SAM apresenta elevada afinidade pelo óxido formado sobre o alumínio, porém as interações entre a camada de óxido e as SAM nem sempre são satisfatórias, pois o óxido formado na superfície apresenta heterogeneidades, que interferem na formação do filme de SAM. O objetivo desse trabalho foi estudar a proteção à corrosão do alumínio AA 2024-T3 associada ao SAM, após tratamento com desengraxante alcalino. A caracterização eletroquímica foi realizada por espectroscopia de impedância eletroquímica e polarização potenciodinâmica anódica em meio de Na2SO4 0,5 mol. L-1 em pH 4,0. A morfologia superficial foi investigada por microscopia óptica. Os resultados mostraram que as SAM promoveram maior proteção do alumínio, quando este foi pré-tratado com o desengraxante.

Self-assembly molecules (SAM - Self Assembly Monolayer) are corrosion inhibitors, due to their capacity to organize on surfaces, forming thin films. SAM presents a high affinity to aluminum oxide. However, the interactions between the oxide layer and SAM are not always satisfactory; therefore the oxide formed on the surface presents heterogeneities that hinder SAM film formation. The aim of this work was to study the corrosion protection of aluminum AA 2024-T3 associated with SAM, after treatment with alkaline degreasing. The electrochemical characterization was carried out by electrochemical impedance spectroscopy and anodic potentiodynamic polarization in Na2SO4 0,5 mol.L-1 in pH 4,0. The superficial morphology was investigated by optic microscopy. The results showed that SAM promoted greater aluminum protection when this was pretreated with degreasing.