A countercurrent centrifugal extractor with an inner rotor and a stationary outer wall has been developed in which aqueous and organic phases flow countercurrently between two walls. The formation of stable Taylor vortices in the gap makes multistage extraction possible. Understanding the relation between flow state and percent extraction is important for achieving a greater number of theoretical stages in a single extractor. Hence, oil-water countercurrent flow is measured by ultrasonic velocity profiling, without disturbing the flow, under different feed rates of solutions and rotating speeds of the inner rotor. In continuous extraction tests, Zn 2 + in nitric acid and di-(2-ethylhexyl)-phosphoric acid diluted by n-dodecane are used. Measurement results are verified by numerical simulation. Finally, a correlation chart of flow patterns and operating conditions is prepared.
The optical constants of HgTe and HgSe are determined in the photon energy region 1.7∼3.5 eV from ellipsometric measurements at room temperature. The structures associated with the E
1 and E
1+Δ
1 band edges are found in the extinction coefficient spectra at energy values nearly coincident with the data of the normal incidence reflectivity for both materials. Tentative surface film corrections are made at several photon energies.
PbTiO3 thin films were prepared by sputter-assisted plasma chemical vapor deposition (CVD) on Pt-coated glass substrates at a substrate temperature of 500°C. As the source materials, a Pb metal target, TiCl4 gas and O2 gas were used. The crystal structures of the films changed from a pyrochlore phase to a perovskite one, and to a PbO (red) one with increasing Pb/Ti atomic ratio.
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