The primary crystallite size of titania powder relates to its properties in a number of applications. Transmission electron microscopy was used in this interlaboratory comparison (ILC) to measure primary crystallite size and shape distributions for a commercial aggregated titania powder. Data of four size descriptors and two shape descriptors were evaluated across nine laboratories. Data repeatability and reproducibility was evaluated by analysis of variance. One-third of the laboratory pairs had similar size descriptor data, but 83% of the pairs had similar aspect ratio data. Scale descriptor distributions were generally unimodal and were well-described by lognormal reference models. Shape descriptor distributions were multi-modal but data visualization plots demonstrated that the Weibull distribution was preferred to the normal distribution. For the equivalent circular diameter size descriptor, measurement uncertainties of the lognormal distribution scale and width HHS Public Access Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript parameters were 9.5% and 22%, respectively. For the aspect ratio shape descriptor, the measurement uncertainties of the Weibull distribution scale and width parameters were 7.0% and 26%, respectively. Both measurement uncertainty estimates and data visualizations should be used to analyze size and shape distributions of particles on the nanoscale.

Catalytic performance and the surface character of the Ga2O3 supported Bi _ Mo complex oxides were studied to achieve direct formation of methacrolein from isobutane.Bi2Mo3O12 (α phase) and Bi2Mo1O6 (γ phase) showed higher catalytic activity than Bi2Mo2O9 (β phase) for isobutane partial oxidation. Supporting Ga2O3, which is an active catalyst for dehydrogenation of hydrocarbons, onto the oxides, enhanced the catalytic activity.The optimum amount of supported Ga2O3 on Bi2Mo3O12 was about 3 wt% for methacrolein formation. In the presence of oxygen, a remarkable amounts of hydrogen over Ga2O3 during the isobutane oxidation but no hydrogen was formed over Ga2O3/Bi2Mo3O12. It is confirmed from TPR that Ga2O3 and Bi2Mo3O12 were not reduced until 550°C but the reduction of Ga2O3/Bi2Mo3O12 started at 350-380°C. The on-set temperature in TPR of the Bi _ Mo complex oxides decreased to 350-380°C from 500°C by the supporting Ga2O3 onto the oxides, and the catalysts after TPR measurement are composed of BiO, Bi, and MoO2 in addition to Bi2Mo3O12. These results suggest that the hydrogen spillover took place over supported catalyst.Ga2O3/Bi2Mo3O12 catalyst showed higher activity and high selectivity for methacrolein at 450°C. The improvement in the selectivity for methacrolein of the Ga2O3/Bi2Mo3O12 may be explained as following. Isobutane is adsorbed on the surface of Ga2O3 to form hydrogen atom and t-butyl fragment and both formed species migrates to Bi2Mo3O12 surface. Migrated hydrogen may modify the Bi2Mo3O12 surface property by the reaction with oxide ions, which is active for the deep oxidation resulting in high selectivity for methacrolein.In the non-aerobic oxidation of isobutane over the Ga2O3/Bi2Mo3O12 catalyst, the formation rate of COx significantly reduced, and methacrolein and isobutene were selectively obtained when the reduction degree of the catalyst was lower than 0.3% at 450°C.

Separation by means of supported liquid membranes is a useful method for the preparation and preconcentration of radioactive nuclides. The permeation of rare earth elements through a bis(2-ethylhexyl) hydrogen phosphate-decalin membrane supported on a microporous polytetrafluoroethylene sheet was studied using a multitracer containing radioactive nuclides of Sc, Zr, Nb, Hf, Ce, Pm, Gd, Yb, and Lu. Permeation rates of these elements from feed solutions of various acidity to receiving solutions of 0.5 mol.dm 3 HC1 were determined simultaneously. The feed solution at pH 1.4 gave the highest permeation rate for Ce, Pm, and Gd, amounting to about 95% of permeation for Ce and Pm, 80% for Gd, and 10% for Yb in 21 h. Scandium, Zr, Nb, Hf, and Lu were not transported at all from the feed solution. Permeation rates of Yb and Lu from the feed solution at pH 1.4 to receiving solutions of 0.75, 1.0, 2.3, and 4.0 mol.dm 3 HC1 increased with the concentration. The results obtained indicate that the light rare earth elements can be separated from the heavy ones by this method.