Surface properties of rare-earth (RE) doped ceria (RE = Sm, Gd, Pr, and Tb) were investigated by UV (325 nm) and visible (514, 633, and 785 nm) Raman spectroscopy, combined with UV-vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectra techniques. It was found that the optical absorption property of samples, the wavelength of detecting laser line, and the inhomogeneous distribution of the dopants significantly affected the obtained surface information, namely, the peak intensity and shape at ca. 460 and 570 cm(-1), as well as the observed oxygen vacancy concentration (A(570)/A(460)). The UV laser line detected the surface information of RE-doped ceria and disclosed the presence of many oxygen vacancies in the samples. The visible laser lines penetrated into the inner layer of the Sm- or Gd-doped CeO(2) and reflected the whole information of samples because of their weak absorptions of the visible laser. However, the Pr- or Tb-doped CeO(2) absorbed visible light strongly; thus, the laser can only determine the outer surface information of the sample.

No abstract

No abstract

The Pt catalysts supported on hexagonal BN (Pt/BN) are highly active and stable for propane combustion, with the highest specific reaction rate of 92.3 μmol gPt –1 s–1 and turnover frequency of 0.037 s–1 obtained on a 0.2Pt/BN catalyst at 220 °C. The Pt oxide in the catalyst could be partially reduced to the metallic state by propane during the reaction, which is beneficial for the improvement of activity, indicating that metallic Pt might be the active sites. The highly dispersed Pt particles stabilized at the grain boundary of BN could be more easily reduced in the reaction than those on the surface and thus are more active. Moreover, kinetic investigation reveals that the apparent activation energy of the Pt species at the grain boundary (111.6 ± 8.0 kJ mol–1) is much lower than that on the surface (172.4 ± 16.5 kJ mol–1), suggesting different reaction pathways on these catalysts and the possible participation of the grain boundary of the BN support in the reaction.

In this study, we examined the effect of progesterone on histopathologic and functional outcomes of intracerebral hemorrhage (ICH) in 10–12-month-old mice. Progesterone or vehicle was administered by intraperitoneal injection 1 hour after collagenase-induced ICH and then by subcutaneous injections at 6, 24, and 48 hours. Oxidative and nitrosative stress were assayed at 12 hours post-ICH. Injury markers were examined on day 1, and lesion was examined on day 3. Neurologic deficits were examined for 28 days. Progesterone posttreatment reduced lesion volume, brain swelling, edema, and cell degeneration and improved long-term neurologic function. These protective effects were associated with reductions in protein carbonyl formation, protein nitrosylation, and MMP-9 activity and attenuated cellular and molecular inflammatory responses. Progesterone also reduced VEGF expression, increased neuronal-specific Na+/K+ ATPase α3 subunit expression, and reduced PKC-dependent Na+/K+ ATPase phosphorylation. Furthermore, progesterone reduced glial scar thickness, myelin loss, brain atrophy, and residual injury volume on day 28 after ICH. With multiple brain targets, progesterone warrants further investigation for its potential use in ICH therapy.