No abstract

Proximal humerus fractures are becoming more common due to the aging of the population, and more related scientific research is also emerging. Biomechanical studies attempt to optimize treatments, taking into consideration the factors involved, to obtain the best possible treatment scenario. To achieve this, the use of finite element analysis (FEA) is necessary, to experiment with situations that are difficult to replicate, and which are sometimes unethical. Furthermore, low costs and time requirements make FEA the perfect choice for biomechanical studies. Part of the complete process of an FEA involves three-dimensional (3D) bone modeling, mechanical properties assignment, and meshing the bone model to be analyzed. Due to the lack of standardization for bone modeling, properties assignment, and the meshing processes, this article aims to review the most widely used techniques to model the proximal humerus bone, according to its anatomy, for FEA. This study also seeks to understand the knowledge and bias behind mechanical properties assignment for bone, and the similarities/differences in mesh properties used in previous FEA studies of the proximal humerus. The best ways to achieve these processes, according to the evidence, will be analyzed and discussed, seeking to obtain the most accurate results for FEA simulations.

In this paper, we assessed the association (relative risk, RR) between the exposure to PM10 and PM2.5 (as a continuous variable and as categories of low or high pollution exposure) on the incidence of pulmonary tuberculosis (PTB) in Mexicali, Baja California, Mexico. We used a weekly, lagged multiple Poisson regression model. We observed a 10-week delayed effect for PM10 and PM2.5 in all PTB cases and in male cases with PTB. An 11-week delayed effect occurred in the female PTB cases. For all the PTB cases, the RR rose by 2.4% (95% CI: 2.1, 2.6, p<0.10) for each 10 µg/m3 increase of PM10 in the continuous exposure and by 3.6% (CI: 3.3, 4.0, p<0.05) in the high pollution exposure category, and by 3.2% (CI: 2.9, 3.4, p<0.05) for each 10 µg/m3 increase of PM2.5 in the continuous exposure and by 3.9% (CI: 3.6, 4.3, p<0.05) in the high pollution exposure category. In men, the RR rose by 2.8% (CI: 2.5, 3.1, p<0.10) for each 10 µg/m3 increase of PM10 in the continuous exposure and by 4.6% (CI: 4.2, 5.0, p<0.05) in the high pollution exposure category, and by 3.4% (CI: 3.1, 3.7, p<0.05) for each 10 µg/m3 increase of PM2.5 in the continuous exposure and by 4.2% (CI: 3.8, 4.6, p<0.05) in the high pollution exposure category. In women, the RR rose by 5.1% (CI: 4.7, 5.5, p<0.05) for each 10 µg/m3 increase of PM10 in the continuous exposure and by 5.3% (CI: 4.7, 5.8, p<0.10) in the high pollution exposure category, and by 4.3% (CI: 3.8, 4.8, p<0.10) for each 10 µg/m3 increase of PM2.5 in the continuous exposure and by 5.3% (CI: 4.8, 5.9, p<0.10) in the high pollution exposure category. PM air pollution appears to associate with the incidence of PTB in the population of Mexicali.

RESUMEN En los últimos años los materiales compuestos se han desarrollado para diferentes aplicaciones del área ingenieril. En este trabajo se expone primeramente un análisis de una matriz polimérica, en este caso resina epóxica para su aplicación en un material compuesto reforzado con fibras. Se presenta un estudio de las propiedades mecánicas, el cual se llevó a cabo mediante pruebas de tensión realizadas bajo el régimen de la norma ASTM D638; se manufacturaron cinco especímenes de resina los cuales llevaron un proceso de preparación de moldeo adecuado para la optimización de probetas tipo I. El objetivo fue conocer las propiedades de la matriz termoestable para así reforzarla con fibras de carbono y mejorar las propiedades del material compuesto. Posteriormente se analizaron las propiedades mecánicas del material compuesto en el cual se utilizó el refuerzo de fibra de carbono 3k. Para el análisis se fabricaron especímenes con una orientación [0/+45/-45]s; las pruebas realizadas en los especímenes de material compuesto fueron cinco ensayos de tracción basados en la norma ASTM D3039. El proceso de manufactura empleado para la realización de los especímenes de material compuesto fue el método VACCUM BAG WET LAY-UP. Se comprobó que las probetas de matriz polimérica de resina epóxica generan burbujas por el mezclado y por el curado al ambiente; así mismo estas burbujas trabajan como concentradores de tensiones que debilitan el material en pruebas de tracción. En comparación con las propiedades mecánicas del material compuesto, estos muestran un mejor comportamiento por el refuerzo de fibra de carbono y por el proceso de manufactura al vacío.

A B S T R A C TThe wide variety of composite materials based on carbon fiber has come to revolutionize the material industry, largely replacing metallic materials such as aluminum and steel alloys mainly used in the aerospace industry. This study was performed a machining procedure for an orthogonal symmetric balanced composite and a comparative analysis of the structural behavior into flexion between the aluminum 6061 T6 and a composite material. The analyzed materials were tested by three procedures; calculation, finite element analysis (ANSYS) and experimentation (extensiometry). According to our results, the best machining methods were to use a saw cutter or the CNC Haas machine with the help of the aluminum fixture, due to cutting process did not make any damage to composite material.