Fabricación de material de referencia 72a (aleación Cu-Al) utilizando la técnica de aleación mecánica

Los materiales de referencia empleados para la técnica de discriminación de energía de rayos X (EDE) requieren que su homogeneidad satisfaga los análisis químicos en regiones de aproximadamente 1 a 3 mm de diámetro, condición que la técnica de preparación de aleación mecánica (AM) cumple satisfactoriamente. El material de referencia 72a consiste de una aleación binaria de composición química nominal de Cu – 10 % kg/kg Al. Se preparó el material mezclando la cantidad respectiva de polvos puros de cada elemento y posteriormente se alearon en un molino de alta energía por un tiempo de 10 horas. Se tomaron muestras a diferentes tiempos con el fin de evaluar el avance de la aleación. Los resultados de medición utilizando técnicas de microsonda y gravimétricos nos indican que la composición del material es Cu 89.91 ± 0.29 % kg/kg y Al 9.81 ± 0.49 % kg/kg

Intercomparación en análisis cuantitativo por espectrómetro de dispersión de energía de rayos X (EDE)

Las intercomparaciones son una base sólida para consolidar un sistema de calidad y un sustento importante en las aspiraciones para obtener la certificación de un laboratorio. Con éstas, el desempeño analítico de cada laboratorio tiene una evaluación objetiva al comparar sus valores con los mejores resultados de otros laboratorios, asegurando siempre la confidencialidad de los participantes [1]. El Centro Nacional de Metrología (CENAM) organizó el primer ejercicio de intercomparación de microanálisis por espectrometría de discriminación de energía de rayos X (EDE). Se realizó una invitación pública a los laboratorios que desearan participar en la prueba 610-IL-0998, logrando la participación de 7 laboratorios. Los resultados indican que los laboratorios que utilizaron materiales de referencia y accesorios que permiten tener mayor control sobre el proceso de medición obtienen resultados con menor sesg

A novel Island Model based on Coral Reefs Optimization algorithm for solving the unequal area facility layout problem

This paper proposes a novel approach to address the Unequal Area Facility Layout Problem (UA-FLP), based on the combination of both an Island Model and a Coral Reefs Optimization (CRO) algorithm. Two different versions of this Island Model based on Coral Reefs Optimization Algorithm (IMCRO) are proposed and applied to the UA-FLP. The structure of flexible bays has been selected as effective encoding to represent the facility layouts within the algorithm. The two versions of the proposed approach have been tested in 22 UA-FLP cases, considering small, medium and large size categories. The empirical results obtained are compared with previous state of the art algorithms, in order to show the performance of the IMCRO. From this comparison, it can be extracted that both versions of the proposed IMCRO algorithm show an excellent performance, accurately solving the UA-FLP instances in all the size categories

Experimental study on the performance of thermosyphon solar water heater in Arequipa, Peru

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.An experimental device was design and built to evaluate the performance of a solar water heating system. Flat-plate solar collectors system were studied considering parallel configuration. Temperature sensors (k type thermocouple), a differential pressure transducer, a turbine type flow meter, and a pyranometer (global solar irradiance) were installed at strategic points for continuous monitoring. The studied parameters were: temperature at the inlet and outlet of the solar collectors and of the tank, heat absorbed by water, pressure drop and mass flow of water. The result shows the performance of the solar collectors system in specific conditions of the Arequipa city in Peru.dc201

A 3-year Mediterranean-style dietary intervention may modulate the association between adiponectin gene variants and body weight change

Purpose Adiponectin gene variations have been associated with obesity. There are few interventional studies analyzing this association. The aim of this study was to analyze the effects of a nutritional intervention with Mediterranean-style diet and three (-4034A/C, +45T/G and +276 G/T) adiponectin gene variants on 3-year body weight changes in high cardiovascular risk patients Subjects and methods A total of 737 participants, aged 55-80 at high cardiovascular risk were assigned to a low-fat diet or to a Mediterranean-style diet (MD) groups, one with high intake of virgin olive oil (VOO) and the other with high intake of nuts. Anthropometric parameters were taken at baseline and after 3-year follow-up, and the genotyping of the -4034A/C, +45T/G and +276 G/T polymorphisms was done. Results GG genotype of the +45T/G polymorphism was associated with 3-year higher body weight gain (B=1.399; B=0.043). TT genotype of the +276G/T polymorphism was linked to the highest 3-year body weight gain in men. Both Mediterranean diets appeared to reverse this effect (p for interaction=0.053). Conclusion Adiponectin gene variation appeared to be associated with 3-year body weight changes in a high cardiovascular risk population. This association may be modulated by a nutritional intervention with a Mediterranean-style diet

Langerhans cell histiocytosis in the maxillofacial area in adults : report of three cases

Langerhans cell histiocytosis (LCH) is a disease of unknown etiology, characterized by proliferation of pathological Langerhans cells within different organs. It mainly affects children, but adult cases also occur, with an incidence rate of one to two per million. The head and neck are affected in almost 90% of cases. Diagnosis is made by means of histopathological analysis, and imaging studies are necessary in order to determine extent of the disease. There are no controlled trials proposing an optimal treatment protocol for LCH. Prognosis in adults is generally good due to the slow evolution of the disease and its favourable response to treatment. In our report, we present three cases of LCH in patients aged 16, 24, and 28 years respectively, with primary manifestation in the maxillofacial area. A literature review was also conducted