Showing papers by "S. A. Tomás published in 2005"
TL;DR: In this paper, the ability of composite edible coatings to preserve the quality of guava fruit (Psidium guqjava L.) at 20°C was studied for a period of 15 days.
Abstract: The ability of composite edible coatings to preserve the quality of guava fruit (Psidium guqjava L.) at 20°C was studied for a period of 15 days. The edible coatings were formulated with candelilla wax blended with white mineral oil as the lipid phase and mesquite gum as the structural material. The use of edible coatings prolonged the shelf life of treated fruits by retarding ethylene emission and enhancing texture as compared to control samples. At the sixth day, the ethylene produced by the control samples was fivefold higher than the ethylene produced by the coated samples. In addition, the physiological weight loss of coated fruits was nearly 30% lower than the control samples.
24 citations
TL;DR: The optical properties of the R6G-doped thin films were characterized by photoacoustic, excitation, and fluorescence spectroscopies as discussed by the authors, and the optical absorption of undoped rutile-phase bulk TiO2 was calculated and compared to the experimental results.
Abstract: Amorphous titanium dioxide (TiO2) thin films doped with rhodamine 6G (R6G) were deposited on glass substrates by the sol-gel process. The optical properties of the films were characterized by photoacoustic, excitation, and fluorescence spectroscopies. The absorption spectra of the R6G-doped TiO2 films exhibited two well-defined absorption regions: an absorption band over 2.0 eV attributed to rhodamine 6G and a band above 3.0 eV corresponding to TiO2 absorption. While the onset of the R6G absorption band was shifted by 0.06 eV towards lower energies as the R6G doping concentration increased within the interval of 0.01–0.10 mol %, the onset to high absorption (TiO2 band) for the doped films decreased only by 0.01 eV within the same interval. In addition, the optical absorption of undoped rutile-phase bulk TiO2 was calculated and compared to the experimental results. The estimated theoretical value of rutile TiO2 sample was 3.0 eV. This theoretical result shows good agreement when compared with the experimen...
21 citations
TL;DR: In this article, the variation of the ethene content in atmospheric samples simultaneously collected in stainless-steel containers at three stations of the local government's air quality monitoring network in November 1999 and March 2000 was assessed.
14 citations
TL;DR: The optical properties and the band structure of TiO2 Sol–gel thin films prepared by the sol–gel process and doped with methylene blue or rhodamine were studied by absorption, excitation and emission spectroscopy.
9 citations
TL;DR: In this paper, photoacoustic spectra of molecular materials based on the assembling of the [Fe(CN)6] molecular block were recorded and evaluated, and an intense absorption band around 600 nm was observed for compounds where the valence of the involved metals allows charge transfer through the CN ligand.
Abstract: Photoacoustic spectra of molecular materials based on the assembling of the [Fe(CN)6] molecular
block were recorded and evaluated An intense absorption band around 600 nm was observed for
compounds where the valence of the involved metals allows charge transfer through the CN ligand (inner
photo-induced redox reactions) In the absence of this transition, only the signal corresponding to d-d
transitions within the metal was observed, which falls below 450 nm This suggests that photoacoustic
spectroscopy provides a fast and reliable method to explore the existence of tunable photo-induced charge
transfer in molecular materials
5 citations
TL;DR: In this paper, the optical properties of titania (TiO 2 ) thin films prepared by the sol-gel process and doped with rhodamine 6G were studied by Photoacoustic Spectroscopy.
Abstract: The optical properties of titania (TiO 2 ) thin films prepared by the sol-gel process and doped with rhodamine 6G were studied by Photoacoustic Spectroscopy. Rhodamine 6G-doping was achieved by adding 0.01%, 0.02%, 0.05% y 0.1% mol rhodamine to a solution that contained titanium isopropoxide as precursor. Two absorption regions were distinguished in the absorption spectrum of a typical rhodamine 6G-doped TiO 2 film. A shift of these bands occured as a function of rhodamine 6G-doping concentration. In addition, the optical absorption and band gap energy for rutile-phase TiO 2 films were calculated employing the full-potential linearized augmented plane wave method. A comparison of these calculations with experimental data of TiO 2 films prepared by sol-gel at room temperature was performed.
4 citations