Shielding gas is a key element in GMAW (Gas Metal Arc Welding). It represents only a small percentage of the overall production cost, and its proper choice makes possible to obtain well shaped and faultless beads, increasing both productivity and quality and therefore resulting cost saving. The influence of several shielding gases on the fusion characteristics of GMAW using solid wires of austenitic stainless steels is assessed in this work. Beads on plate welds are performed on AISI 304 steel plates using ER 308LSi welding wire according to AWS A5.9 and the following shielding gases: Ar, Ar-O2, Ar-CO2, Ar-He-CO2, He-Ar-CO2, Ar-CO2-NO, Ar-NO, Ar-He-H2, Ar-He. For these gas mixtures, stability and geometry of the weld are evaluated, determining depth of penetration, bead reinforcement height, width of the bead, wetting angle, fusion angle, total fusion area, plate fusion area and dilution. A comparative analysis of the results which are obtained with the different gas mixtures is carried out.

To evaluate the usefullness of the collecting method of blood samples in filter paper strips for anti-dengue antibody detection using an ELISA Inhibition test which has been recently developed in our laboratory, blood samples collected on filter paper strips and serum samples were obtained from the same blood donors. Both samples were kept at -20ºC and tested at 15 days, 3 and 6 months. Titers were determined in positive samples. Comparing the results, no significant differences were found between serum samples and blood samples collected in filter paper strips in relation to the number of negative and positive cases. Nevertheless, it was observed in both types of samples a decrease of the antibody titers (one dilution) in the longest period of our study (6 months).

Para evaluar la utilidad del método de recolección de muestras de sangre en papel de filtro para la detección de anticuerpos anti-dengue mediante un ELISA de Inhibición recientemente desarrollado en nuestro laboratorio, se realizó una toma simultánea de muestras de sangre en papel de filtro y de suero, de donantes de Banco de Sangre. Ambas muestras fueron conservadas a -20ºC y probadas a los 15 dias, 3 y 6 meses respectivamente. A las muestras que resultaron positivos se les amplió el rango de dilución para determinar título. Al realizar la comparación entre ambas muestras, sangre en papel de filtro y suero, encontramos que no existían diferencias de detección significativas, tanto para los casos positivos como los negativos. No obstante se observó en ambas muestras y de forma general una disminución del titulo de anticuerpos (una dilución) al transcurrir el tiempo máximo establecido en nuestro estudio (6 meses).