ABSTRACT The objective of this study was to evaluate the effect generated by a thermal treatment on the dimensional changes and compression behavior of three wood species from commercial plantations (Eucalyptus nitens, Tectona grandis and Gmelina arborea). To accomplish the goal, dilatometric and compression tests were performed in the three directions of wood. It was found a high anisotropy of the coefficient of linear thermal expansion (CTE) as well as of the compression strength of the woods. Higher values of CTE in the tangential direction than in the radial direction were measured, meanwhile in the longitudinal direction were null. In terms of mechanical strength, the longitudinal direction showed the highest strength. The radial strength was slightly higher than the tangential one. Thermal treatment increased the strength to compression and the resistance to deformation in the elastic region. The modulus of elasticity increased up to 30.9%, the stress at proportional limit up to 27.3% and the modulus of rupture up to 30.3%, in the longitudinal direction. The thermal treatment had a higher effect on the mechanical properties of the lowest density wood. On the contrary, the mass loss increased for these species, finding values around twice than those obtained for the denser wood.

A composite of Ti6Al4V reinforced with CoCrMo particles is fabricated by conventional powder metallurgy and semi-solid sintering. Composites are fabricated by mixing 20% wt. of CoCrMo reinforcing particles into the Ti6Al4V matrix. Sintering is studied by dilatometry tests between 1050 and 1130 °C and compact characterization is performed by SEM and XRD. Microhardness is evaluated on the polished surface in order to obtain the mechanical properties. It is found that densification is achieved by the formation of a liquid phase due to a eutectic point formed by the Ti and Co at around 1130 °C. Composites with 93% of relative density are obtained. Their microstructure is composed by the Ti6Al4V matrix surrounded by a Ti2Co phase. Average microhardness of composites is higher than that obtained for monolithic samples of both alloys. It is assessed that the control of the liquid phase is the key to obtain highly dense composites that could be used as dental or orthopedic implants.

Abstract: This paper presents the soft magnetic properties of the Fe-, Ni-, Coand Fe-Co-Ni polymer composites. The composites were obtained with Fe, Ni and Co powders (99.9% purity) with particle sizes of 150, 10 and 2 mm, respectively. Ring-shaped samples were obtained using uniaxial compaction at 91 MPa. The Fe-Co-Ni-polymer composite has the highest value of the magnetic permeability (μ=54) at 107 Hz and saturation magnetization (Ms=10000 Am2Kg-1) higher than the Ni-polymer composite (4100 Am2Kg-1).

Resumen: Este documento presenta las propiedades magnéticas suaves de los compositos Fe-polímero, Ni-polímero, Co-polímero y Fe-Ni-Co-polímero. Los compositos fueron obtenidos con polvos de Fe, Ni y Co (pureza 99.9%) con tamaños de partícula de 150, 10 and 2 mm, respectivamente. Muestras con forma anillada fueron obtenidas usando compactación uniaxial a 91 MPa. El composito Fe-Ni-Co-polímero tiene valores altos de permeabilidad magnética (μ=54) a 107 Hz y magnetización de saturación (Ms=16000 Am2Kg-1) mayor que el composito Ni-polímero (4100 Am2Kg-1).

Resumo Em aços inoxidáveis o dano microestrutural é causado pela precipitação de carbonetos de cromo ou de fase sigma. Estes microcomponentes são prejudiciais em soldas de aço inoxidável, porque eles levam a corrosão intergranular. No entanto, eles são propensos a aparecer na microestrutura da zona afetada pelo calor de soldas em aço inoxidável. Isto é particularmente importante para reparos de componentes industriais feitos de aço inoxidável austenítico. Réplica metalográfica pode ser aplicada para identificar a necessidade de reparos em componentes de aço AISI304 inoxidável onde é difícil assegurar que tal fase está presente na microestrutura da ZTA. A necessidade de inspeção microestrutural não destrutiva no aço inoxidável AISI 304 está associada a impossibilidade de se obter corpos de prova para análise via técnicas convencionais. Neste trabalho, propõe-se a aplicação de réplica metalográfica, a fim de identificar danos microestruturais em soldas de aço inoxidável AISI 304. Os resultados deste estudo mostraram que as micrografias da superfície externa do conjunto de peças soldadas representam a microestrutura da ZTA do componente de aço inoxidável porque mostram a presença de carbonetos metálicos precipitados nos contornos de grão ou de fase sigma.

Abstract In stainless steels, microstructural damage is caused by precipitation of chromium carbides or sigma phase. These microconstituents are detrimental in stainless steel welds because they lead to weld decay. Nevertheless, they are prone to appear in the heat affected zone (HAZ) microstructure of stainless steel welds. This is particularly important for repairs of industrial components made of austenitic stainless steel. Non-destructive metallography can be applied in welding repairs of AISI 304 stainless steel components where it is difficult to ensure that no detrimental phase is present in the HAZ microstructure. The need of microstructural inspection in repairs of AISI 304 is caused because it is not possible to manufacture coupons for destructive metallography, with which the microstructure can be analyzed. In this work, it is proposed to apply in situ metallography as non-destructive testing in order to identify microstructural damage in the microstructure of AISI 304 stainless steel welds. The results of this study showed that the external surface micrographs of the weldment are representative of HAZ microstructure of the stainless steel component; because they show the presence of precipitated metallic carbides in the grain boundaries or sigma phase in the microstructure of the HAZ.

Collagenous sprue is a rare disease of the small bowel characterized by mucosal atrophy and excessive subepithelial collagen deposition. The etiology remains unclear and the diagnosis is based upon patient's clinical picture and anatomopathological findings. Clinically, collagenous sprue is characterized by persistent diarrhoea, severe malabsorption, multiple nutrient deficiencies and progressive weight loss. Differential diagnosis includes celiac disease, which is mandatory to rule out because of their frequent association. Gluten-free diet is the first therapeutic step, but it usually is not effective. However, recent studies show high success rates with immunomodulators, mainly corticosteroids. We report the case of a patient presenting with chronic diarrhea and severe malabsorption who was diagnosed with collagenous sprue, with no response to gluten free diet, but with excellent response to budesonida.

El esprúe colágeno es una patología infrecuente del intestino delgado caracterizada por atrofia de la mucosa y depósito excesivo de colágeno a nivel subepitelial. Su etiología es desconocida y su diagnóstico se realiza en base a la presencia tanto de un cuadro clínico compatible como de hallazgos anatomopatógicos sugestivos. Los pacientes suelen presentar diarrea crónica, malabsorción, deficiencias nutricionales graves y una marcada pérdida ponderal. Dentro del diagnóstico diferencial es mandatorio descartar enfermedad celiaca por su frecuente asociación a la misma. La dieta sin gluten es el primer escalón terapéutico, pero generalmente no es efectiva. Sin embargo, estudios recientes señalan altas tasas de éxito mediante el uso de inmunomoduladores. Presentamos el caso de un paciente con diarrea crónica y malabsorción grave diagnosticado de esprúe colágeno, sin respuesta a la dieta sin gluten, en el que el tratamiento con budesonida ha conseguido una excelente respuesta.

La búsqueda de alternativas energéticas de origen renovable y la disminución de gases de efecto invernadero provenientes de la descomposición de desechos orgánicos hacen del biogás una prometedora alternativa para la sustitución de combustibles fósiles y para la valorización energética de residuos orgánicos en zonas urbanas, rurales y agroindustriales. En el presente trabajo se realizó un análisis de sensibilidad de las propiedades de combustión del biogás con enriquecimiento de aire con oxígeno en un rango entre 22 y 35% O2. Los resultados indican que la velocidad de deflagración laminar, la temperatura de llama adiabática, el porcentaje en volumen de CO2, la temperatura de rocío y el porcentaje de H2O se incrementaron cuando el porcentaje de oxígeno en el aire fue mayor que 21% O2, mientras que propiedades como el volumen de aire estequiométrico, volumen de humos húmedos, volumen de humos secos y la energía mínima de ignición,disminuyeron.

Research into renewable energy as energy alternatives and decreasing greenhouse gases from organic waste decomposition make biogas a promising alternative for fossil fuel substitution and an energy source from recovery of organic waste in urban, rural and agroindustrial areas. This paper presents a sensitivity analysis of oxygen-enriched biogas combustion properties ranging from 22% to 35%. Results showed that properties such as deflagration speed, adiabatic flame temperature, dew temperature and CO2 and H2O percentage increased when oxygen percentage in air was increased. On the other hand, properties such as minimum ignition energy, stoichiometric air volume and dry fume volume decreased when the O2 percentage in air was higher than 21%.