Modulated differential photoacoustic cell to study the gelatinization in a starch-water suspension

In this paper the design and implementation of a novel Differential Photoacoustic Cell (DPC) system is presented. The system was used to study the thermo optic transition in water-starch suspension called gelatinization. The melting temperature of Gallium was used to calibrate the temperature of the system. Both temperature values for starch gelatinization and gallium melting were agreed with those obtained using differential scanning calorimetry (DSC). The results show that this system is suitable to study other thermal processes in food or any thermal transition at low temperature

Influence of substrate on structural, morphological and optical properties of ZnO films grown by SILAR method

ZnO films were obtained by successive ionic layer adsorption and reaction (SILAR) method from four different substrates: glass microslides, corning glass, quartz and silicon with and without oxide layer. For films deposition, a precursor solution of ZnSO4 was used, complexed with ammonium hydroxide. Prior to the film deposition, wettability of the substrates was analysed using a CCD camera. It was found that the Si without the oxide layer substrate shows hydrophobic behaviour, which makes the films less adherent and not uniform, while in the other substrates, the behaviour was optimal for the growing process. ZnO films grown on glass microslides, corning glass, quartz and Si with oxide layer were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Vis techniques. According to the XRD patterns, the films were polycrystalline, with hexagonal wurtzite structure and the patterns mentioned showed significant differences in crystallite sizes, microstrain and texture coefficient with respect to the employed substrates. The morphology of the ZnO films constituted by rice-like and flower-like structures shows differences in form and size depending on the substrate. The UV-Vis spectroscopy results show that the substrate did not influence the band gap energy value obtained from films.Fil: Jiménez García, F. N.. Universidad Autónoma de Manizales; ColombiaFil: Londoño Calderon, Cesar Leandro. Universidad Autónoma de Manizales; Colombia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Espinosa Arbeláez, D. G.. Universidad Nacional Autónoma de México; MéxicoFil: Del Real, A.. Universidad Nacional Autónoma de México; MéxicoFil: Rodríguez García, M. E.. Universidad Nacional Autónoma de México; Méxic