ABSTRACT
Introducción. El tabaquismo es responsable de una gran cantidad de muertes en el mundo, la gran prevalencia del tabaquismo entre adolescentes, así como la baja edad de inicio del consumo, genera preocupación y la necesidad de implementar intervenciones específicas a esta población. Objetivo. Evaluar los efectos de una charla antitabaco en adolescentes de colegios públicos y privados en la Región Metropolitana de Santiago. Métodos. Estudio cuantitativo cuasi-experimental, se realizó una charla antitabaco en dos colegios (público y privado), se evaluó la motivación para dejar de fumar con el Test de Richmond en una muestra de 13 estudiantes pre y post charla. Resultados. hubo una mejora en los puntajes de Richmond post charla en ambos colegios, siendo mayor en el colegio público, sin embargo, la diferencia no fue estadísticamente significativa (p=0,09). Discusión. La evidencia respalda la efectividad de las charlas antitabaco. Existe una relación entre nivel socioeconómico y tabaquismo, sin embargo, no hay otros estudios que comparen la efectividad en los distintos estratos sociales. Se reconocen limitaciones del estudio como el tamaño de la muestra y el muestreo no aleatorio, se recomiendan nuevos estudios que incluyan otras variables. Conclusiones. A pesar de limitaciones del estudio, se respalda la implementación de charlas antitabaco en entornos educativos, enfatizando la necesidad de adaptar estrategias a contextos socioeconómicos específicos para mejorar la salud pública.
Background. Introduction: Smoking is responsible for a significant number of deaths worldwide, and the high prevalence of smoking among adolescents, as well as early age of onset, raises concerns, and the need of targeted interventions for this group. The aim of this study was to assess the effects of an anti-smoking talk on students from public and private schools in the Metropolitan Region of Santiago. Methods. A quasi-experimental quantitative study involving an anti-smoking talk in two schools (public and private) assessed the motivation to quit smoking using the Richmond Test in a sample of 13 students pre and post the talk. Results. There was an improvement in Richmond scores post-talk in both schools, with a greater increase observed in the public school. However, the difference was not statistically significant (p=0.09). Discussion. The evidence supports the effectiveness of anti-smoking talks. A relationship between socioeconomic status and smoking exists, yet there are no studies comparing effectiveness across different socioeconomic strata. Study limitations, such as sample size and non-random sampling, are acknowledged, and further research incorporating additional variables is recommended. Conclusions. Despite study limitations, advocating for the implementation of anti-smoking talks in educational settings is supported, emphasizing the need to adapt strategies to specific socioeconomic contexts to enhance public health.
ABSTRACT
Cellular automata models have emerged as a valuable tool in corrosion management. This manuscript provides an overview of the application of cellular automata models in corrosion research, highlighting their benefits and contributions to understanding the complex nature of corrosion processes. Cellular automata models offer a computational approach to simulating corrosion behavior at the microscale, capturing the intricate interactions between electrochemical reactions, material properties, and environmental factors and generating a new vision of predictive maintenance. It reviews the key features of cellular automata, such as the grid-based representation of the material surface, the definition of state variables, and the rules governing cell-state transitions. The ability to model local interactions and emergent global behavior makes cellular automata particularly suitable for simulating corrosion processes. Finally, cellular automata models offer a powerful and versatile approach to studying corrosion processes, expanding models that can continue to enhance our understanding of corrosion and contribute to the development of effective corrosion prevention and control strategies.
ABSTRACT
In this work, electrochemical techniques were employed to evaluate the contribution to the corrosion and corrosion inhibition of 2024-T3 aluminum alloy by two Gram-positive bacteria. In addition, polarized impedance was used to determine the microbial effect on the cathodic and anodic reactions. These microorganisms were collected from a tropical environment due to the favorable bacterial growth of this kind of climate. The alloy was exposed to the sterile medium and inoculated for up to 12 days evaluating the microbiological and electrochemical behavior. The results by linear scanning voltammetry showed that the B. safensis and B. pumilus caused a dual effect of increase and decrease currents, and through electrochemical impedance spectroscopy, showed in some cases, inductive loop, which could be associated with local corrosion and another case, an increasing impedance could be related to protection. In addition, a morphological characterization was performed by scanning electron microscopy before and after exposure, showing an increase in copper precipitation in the vicinity of the intermetallic phases by bacteria, attributed to local corrosion, but, in general, a significant effect of damages was not observed.
Subject(s)
Aluminum , AlloysABSTRACT
Microbially influenced corrosion (MIC) is an aggressive type of corrosion that occurs in aquatic environments and is sparked by the development of a complex biological matrix over a metal surface. In marine environments, MIC is exacerbated by the frequent variability in environmental conditions and the typically high diversity of microbial communities; hence, local and in situ studies are crucial to improve our understanding of biofilm composition, biological interactions among its members, MIC characteristics, and corrosivity. Typically, material performance and anticorrosion strategies are evaluated under controlled laboratory conditions, where natural fluctuations and gradients (e.g., light, temperature, and microbial composition) are not effectively replicated. To determine whether MIC development and material deterioration observed in the laboratory are comparable to those that occur under service conditions (i.e., field conditions), we used two testing setups, in the lab and in the field. Stainless steel (SS) AISI 316L coupons were exposed to southeastern Pacific seawater for 70 days using (i) acrylic tanks in a running seawater laboratory and (ii) an offshore mooring system with experimental frames immersed at two depths (5 and 15 m). Results of electrochemical evaluation, together with those of microbial community analyses and micrographs of formed biofilms, demonstrated that the laboratory setup provides critical information on the early biofilm development process (days), but the information gathered does not predict deterioration or biofouling of SS surfaces exposed to natural conditions in the field. Our results highlight the need to conduct further research efforts to understand how laboratory experiments may better reproduce field conditions where applications are to be deployed, as well as to improve our understanding of the role of eukaryotes and the flux of nutrients and oxygen in marine MIC events.
ABSTRACT
Due to their applicability for manufacturing dense, hard and stable coatings, Physical Vapor Deposition (PVD) techniques, such as High Power Impulse Magnetron Sputtering (HiPIMS), are currently used to deposit transition metal nitrides for tribological applications. Cr-Al-N is one of the most promising ceramic coating systems owing to its remarkable mechanical and tribological properties along with excellent corrosion resistance and high-temperature stability. This work explores the possibility of further improving Cr-Al-N coatings by modulation of its microstructure. Multilayer-like Cr1-xAlxN single films were manufactured using the angular oscillation of the substrate surface during HiPIMS. The sputtering process was accomplished using pulse frequencies ranging from 200 to 500 Hz and the resulting films were evaluated with respect to their hardness, Young's modulus, residual stresses, deposition rate, crystallite size, crystallographic texture, coating morphology, chemical composition, and surface roughness. The multilayer-like structure, with periodicities ranging from 250 to 550 nm, were found associated with misorientation gradients and small-angle grain boundaries along the columnar grains, rather than mesoscopic chemical modulation of the microstructure. This minute modification of microstructure along with associated compressive residual stresses are concluded to explain the increased hardness ranging from 25 to 30 GPa, which is at least 20% over that expected for a film of the same chemical composition grown by a conventional PVD processing route.
