Decomposition of two types of electric wires considering the effect of the metal in the production of pollutants

Combustion runs at 700 °C in a horizontal laboratory furnace were carried out on two different electric wires (PVC and halogen-free wire). Tests were performed in the presence and in the absence of the metal conductor of the wires. The analyses of the polycyclic aromatic hydrocarbons (PAHs), chlorobenzenes (CBzs), chlorophenols (CPhs), mono- to octa-chlorodibenzo-p-dioxin and dibenzofurans (PCDD/Fs), and dioxin-like PCBs are shown. Regarding semivolatile compounds, PAHs production decreases in the presence of metal, while a higher amount of chlorinated compounds are emitted. Respect to the PCDD/Fs, the PVC wire in the presence of metal presents the highest emission, with a much more emission of furans than dioxins. The maximum emission is with 2 or 3 chlorine atom PCDD/Fs. PCBs emission correlates with PCDD/F production and represents 3–4% of total toxicity, determined by using WHO2005 factors.

Electrospinning of silica sub-microtubes mats with platinum nanoparticles for NO catalytic reduction

Silica sub-microtubes loaded with platinum nanoparticles have been prepared in flexible non-woven mats using co-axial electrospinning technique. A partially gelated sol made from tetraethyl orthosilicate was used as the silica precursor, and oil was used as the sacrificial template for the hollow channel generation. Platinum has been supported on the wall of the tubes just adding the metallic precursor to the sol–gel, thus obtaining the supported catalyst by one-pot method. The silica tubes have a high aspect ratio with external/internal diameters of 400/200 nm and well-dispersed platinum nanoparticles of around 2 nm. This catalyst showed a high NO conversion with very high selectivity to N2 at mild conditions in the presence of excess oxygen when using C3H6 as reducing agent. This relevant result reveals the potential of this technique to produce nanostructured catalysts onto easy to handle conformations.

Aplicación de la técnica NAH a la docencia en ingeniería acústica

La técnica Holografía Acústica de Campo Cercano (NAH), es una técnica conocida en el ámbito de la ingeniería acústica que permite reconstruir el campo sonoro y la velocidad de vibración de una fuente sonora a partir de medidas con micrófonos, en un plano paralelo y cercano a la fuente. La técnica se presenta como una alternativa a las medidas de intensidad estándar. En la presente comunicación se explica la metodología seguida para visualizar el efecto sobre la respuesta en frecuencia de un altavoz coaxial de un cambio en el filtro de cruce y comprobar el efecto de un cambio en las condiciones de contorno del panel que forma un altavoz de modos distribuidos (DML). Esta práctica o lección magistral puede llevarse a cabo en una carrera técnica después de haber recibido un curso de acústica y tener nociones básicas sobre transductores acústicos y procesado de señal. Los resultados facilitan el aprendizaje del alumnado y la asimilación de conceptos que se han impartido en etapas anteriores.