RESUMO
We report the synthesis of uniform 2.5 ± 0.4 nm diameter Ce(iii) carbonate clusters deposited on the surface of TiO2 nanoparticles and characterize them using HAADF-STEM and EELS, as well as UV-Vis and FTIR spectroscopies. This material is a highly proficient catalytic antioxidant for the degradation of photocatalytically generated reactive oxygen species (ROS). We observed an unusual U-shaped pH-dependence in its photoprotection catalytic activity, with an optimum function in the near-neutral pH range of 7.7 ± 0.7. This sharp pH dependence is not observed in previously reported bulk Ce(iii) carbonate materials, and it is also not a consequence of Ce(iii) carbonate cluster decomposition. However, it is consistent with a tandem reaction sequence consisting of a biomimetic superoxide dismutase and catalase function, which is dependent on a balance of protons and hydroxide anions for function. Our dissolution-deposition approach for synthesizing nanoscale Ce(iii) carbonate clusters on TiO2 should be generalizable to other carbonates and metal-oxide supports.
RESUMO
Urethral duplication, also called supernumerary urethra, is a rare malformation essentially affecting the boys. It is defined by juxtaposition of two or more muscular channels with urinary tract mucosal lining. Various features may be observed depending on the site of the extra urethra and its incomplete or complete nature. In this study, the authors examined a particular aspect of this malformation, the epispadiac form.
