RESUMEN
Due to the poor chemical stability of CeO2-based materials, doped CeO2 electrolytes are generally used as a stabilized ZrO2 protection layer/doped CeO2 electrolyte bilayer structure. Since the ionic conductivity of stabilized ZrO2 materials is lower than that of doped CeO2 materials, the thickness of the ZrO2 protective layer needs to be optimized. Thus, in this study, nano-porous anodic aluminum oxide template based scandia stabilized zirconia (ScSZ)/gadolinia doped ceria (GDC) bilayer electrolyte low temperature solid oxide fuel cells (LT-SOFCs) are successfully fabricated and investigated. The optimized thickness of the ScSZ protection layer is revealed by physical and electrochemical characterizations to maximize the performance of LT-SOFCs. The 160 nm ScSZ/400 nm GDC bilayer electrolyte LT-SOFC achieves a maximum power density of 252 mW · cm-2 and an open circuit voltage of 1.02 V OCV at 450 °C.
RESUMEN
In order to enhance the dissolution profile and oral bioavailability of megestrol acetate (MA), solid dispersions of MA (MASDs) were formulated with copovidone and crystal sugar as a hydrophilic polymeric carrier and an inert core bead, respectively. Solvent evaporation method and fluidized bed coating technique were employed. MASDs were categorized as crystalline solid dispersion by the characterization of differential scanning calorimetry and X-ray diffraction. The mass-median diameters of MASDs were in a range of 1.4 to 2.6 µm. Based on drug to polymer ratio, MASD (1:1) and (1:2) were considered as optimized formulations, resulting in a smooth-surfaced homogeneously coated layer with enhanced dissolution rate. Dissolution of MASD was gradually increased up to 15 min, after which it reached a plateau. For the initial period, dissolution rates were in the decreasing order of MASD (1:2) ≥ MASD (1:1) > MASD (1:3) > MASD (1:5) > MASD (1:0.5) > MA powder. In the comparative pharmacokinetic study with Megace OS, a reference drug product, MASD (1:1) showed improved bioavailability of over 220% with 2-fold higher C(max) and 30% faster T(max). We conclude that MASD (1:1) is a good candidate for the development of oral solid dosage forms.
