A mathematical model was developed to describe mass transport in polymeric films based on modifications of Fick's law in a continuous macroscopic approach. The purpose of this work was specifically to model the transport of water vapor and oxygen in polymeric films at the pore level, based on physical aspects of the condensation process and the morphology and connectivity of the porous medium, with two-dimensional pore networks representing pore spaces. Using a Pore scale discrete model, we found that the pore-level distributions of liquid (condensate) and vapor as transport phenomena occurred. The vapor and oxygen diffusivities ranged from 4.22×10-6 to 3.16×10-7 cm²/s and from 3.66×10-6 to 2.86×10-7 cm²/s, respectively. Also, the vapor and oxygen permeabilities ranged from 2.61×10-3 to 3.83×10-4 nD (1nD=10-21m²) and from 6.77×10-3 to 1.35×10-3 nD, respectively. The transport properties obtained by the model were compared with the corresponding results for chitosan films obtained in previous experimental studies, showing a partial agreement.

Thermal fluctuations in the electric conductivity of YBa2Cu3O7 - delta superconducting thin films grown on Sr2YSbO6 novel substrate materials in the film form were experimentally studied. YBa2Cu3O7 - delta films were grown by using a dc-technique on Sr2YSbO6 substrates, which were produced by rf magnetron sputtering. X-ray diffraction analysis evidenced that the Sr2YSbO6 films grow on conventional SrTiO3 substrates in a preferential orientation along the (100) planes direction with lattice parameter a=4,43() Å. The YBa2Cu3O7 - delta thin films, grown on Sr2YSbO6 films, exhibit an oriented growth in the (001) crystallographic direction, with lattice constant c=11,65(9) Å. Morphological characterizations were performed by means atomic force microscopy. Experiments of electrical resistivity show that the YBa2Cu3O7 - delta films present a normal-superconducting transition with critical temperature Tc=82,33 K. Fluctuation analysis for the YBa2Cu3O7 - delta thin films were performed by utilizing the concept of logarithmic derivative of the conductivity excess. Above the critical temperature Tc we experimentally determine the occurrence of Gaussian 3D, 2D and fractal fluctuation regimes. A genuinely critical region identified by the exponent lambdaCR=0,35 were obtained close to Tc. This critical regime is effectively described by the 3D-XY model.