Luminescence properties of Yb3+-doped SrTiO3: the significance of the oxygen-titanium charge transfer state on photon downshifting.

Ceramic powders of Sr1-1.5xYbxTiO3 (x = 0.0, 0.0125, 0.025, 0.05 and 0.075) solid solutions were synthesized by the polymeric complex method. The crystal structure, microstructure and optical properties of the powders annealed at 800 °C for 1 h were investigated by X-ray diffraction, scanning electron microscopy, and diffuse reflectance and photoluminescence spectroscopy, respectively. All the solid solutions exhibit a cubic perovskite-like structure. The reflectance spectra show a broadband below 400 nm ascribed to the ligand-to-metal charge transfer (LMCT) O2- → Ti4+ fundamental state. The Yb3+ (λem = 980 nm) excitation spectra show a broadband being also compatible with the LMCT O2- → Ti4+ state, indicating the energy transfer from the host to the Yb3+. The sample with x = 0.025 presents the highest emission intensity upon near UV excitation, which is further enhanced when the powder is treated under an oxygen-rich atmosphere. The luminescence quenching of Yb3+ is explained as due to defects associated with O2- and Sr2+ vacancies. Finally, it is shown that the solid solutions may downshift photons from UV to wavelengths where a crystalline-silicon photovoltaic solar cell has a higher spectral responsivity.

Evolución alejada de la enterocistoplastía por cistitis intersticial / Cytoplasty evolution for interstitial cystitis

Revisamos 11 enterocistoplastías por cistitis intersticial en su evolución alejada. El 64% de los casos tiene más de 4 años de seguimiento. La entrevista a la paciente para evaluar su situación nos demostró resultados discordantes, con un 36% de resultados excelentes y un 36% en que no hubo mejoría alguna. En el resto de los casos, la paciente dijo estar mejor. No nos parece que queda claro cuál es la indicación de esta cirugía, como tampoco que se pueda pronosticar resultados en un caso específico