E. López Cuéllar

Performance of ZnO synthesized by sol-gel as photocatalyst in the photooxidation reaction of NO

ZnO samples were prepared by sol-gel method applying a factorial design in order to improve the photocatalytic properties of the semiconductor oxide in the NO photooxidation reaction. The concentrations of zinc acetate and ammonium hydroxide were selected as critical variables in the synthesis of ZnO. Nine samples of ZnO were obtained as product of the factorial design and were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and N2 adsorption-desorption isotherms. The photocatalytic activity of ZnO samples was associated with the physical properties developed by each sample according to its respective conditions of synthesis. Some photocatalytic reaction parameters, such as mass of photocatalyst, irradiance, and relative humidity, were modified in order to evaluate its effect in the photocatalytic conversion of NO. As a relevant point, the relative humidity played an important role in the increase of the selectivity of the NO photooxidation reaction to innocuous nitrate ions when ZnO was used as photocatalyst.

Strain-Resistivity Behavior of a Ti-45Ni-5Cu Shape Memory Alloy during Superelastic and SATWME Cycling

The strain-resistivity behavior of Ti-45.0Ni-%.0Cu wires has been measured during superelastic cycling. The results are in good agreement with previous results, showing that the main changes of resistivity during superelastic cycling are due to Austenite ↔ Martensite phase changes and anisotropic variant orientation. The true plastic strain (dislocations) does not seem to play an important role for this alloy.