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ABSTRACT: Water vapor diffusion coefficient (WVDC) and thermal diffusivity (alpha) were determined in gelatin-starch films through photothermal techniques. The effect of different variables in the elaboration of these films, such as starch and glycerol concentrations and pH, were evaluated through the response surface methodology. The results indicated that an increase in the glycerol concentration and pH favored the WVDC of the films. On the other hand, alpha was influenced principally by the starch content and pH of the film-forming solution. The minimum alpha value was 4.5 x 10(-4) cm2/s, which is compared with alpha values reported for commercial synthetic polymers.
Analytical Sciences 05/2007; 23(4):457-61. · 1.25 Impact Factor
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ABSTRACT: Thermal diffusivities of Zn1 - xMnxIn2Se4 series are reported in this article. Manganese nominal concentration ranging from x = 0.05 to x = 1. Measurements were performed at room temperature by using the open photoacoustic cell technique. Thermal diffusivity varies from $1.2 \cdot 10^{-2} \frac{cm^2}{s} \ (x=0.05)$ to $0.30 \cdot 10^{-2} \frac{cm^2}{s} \ (x=1)$, follows a close pattern to the crystal parameter variations.
http://dx.doi.org/10.1051/jp4:2005125068.
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ABSTRACT: The thermal diffusivity of Poly(N-vinyl-2-pirrolidone) (PVP) samples was investigated using open photoacoustic cell technique (OPC) as function of molecular weight and crosslinking. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and X~ray diffraction (XRD) techniques were also used to the PVP characterization.
http://dx.doi.org/10.1051/jp4:2005125067.
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ABSTRACT: Phycobiliproteins, the main polypeptidic components of the phycobilisomes (PBS), are biological macromolecules arranged in complex interaction systems to perform light harvesting and conduction. The optical properties of these systems can hardly be studied by conventional spectroscopic techniques. Furthermore this techniques also involve laborious chemical extraction methods. Photoacoustic (PA) spectroscopy was successfully applied to an in situ study of the phycobiliproteins expression in the eukaryotic red algae: Gracilaria chilensis.
http://dx.doi.org/10.1051/jp4:2005125176.
