Submonolayer structures of Ce adsorbed on Mo(110) surface

The surface structure of Ce adsorbed on a Mo(110) surface was studied by reflection high energy electron diffraction. Five kinds of surface structures were found with different deposition coverages in the submonolayer region. These structures have a common feature that Ce atoms possess a periodicity with double spacing at the atomic rows in the Mo[ 10] direction. Observed at 1 ML of Ce coverage was a surface structure related to a deformed fcc Ce(111) plane.     

Rh-catalyzed π-facial selective intermolecular hydroacylation of norbornenes

Rh-catalyzed π-facial selective intermolecular hydroacylations of norbornenes with salicylaldehyde have been attained. In the reaction with norbornylene, the exo-hydroacylated product was produced because of steric hindrance. In the case of norbornadiene, the endo-product was obtained because of chelation effect. Lastly, because of chelation and remote substituent effects, the product formed in the reaction of 7-tert-butoxynorbornadiene was the endo,syn-product. Deuterium-labeling experiments revealed that the hydroacylation stereoselectively proceeded via endo- and exo-intermediates.     

Adsorptive accumulation voltammetry of copper(II) using complex formation reaction with salicylideneamino-2-thiophenol

Summary The cathodic stripping voltammetry of copper(II) was investigated with a method, based on the adsorptive accumulation of the Cu(II)-salicylideneamino-2-thiophenol (SATP) complex on a hanging mercury drop electrode. The copper(II)-SATP complex could be accumulated on the electrode at –0.20 V in 0.01 mol/l nitric acid. The reduction peak of the copper complex was observed by scanning the potential in a negative direction in the differential pulse mode. The calibration curve for copper was linear over the range 5×10^–9–1×10^–7 mol/l. This method was applied to determine copper(II) in GSJ (Geological Survey of Japan) standard rock reference materials.     

Binding position of phenylbutazone with bovine serum albumin determined by measuring nuclear magnetic resonance relaxation time

The binding of phenylbutazone (PB) to bovine serum albumin (BSA) was considered to be predominantly due to hydrophobic interaction based on the thermodynamic parameters obtained by an equilibrium dialysis method. Little variation of proton nuclear magnetic resonance (1H-NMR) chemical shift of PB was found with change in the concentration of PB (0.5-5 mM) or upon the addition of BSA (7.25 x 10(-5) M). The NMR spectrum of PB in 0.1 M phosphate buffer solution at pH 7 showed that PB existed as a mesomeric anion. The spin-lattice relaxation time (T1) of PB was almost concentration-independent, but decreased in the presence of BSA to 36-38% for the phenyl group and 48-100% for the butyl group. The spin-spin relaxation time (T2) of PB was also almost independent of concentration, but was remarkably decreased in the presence of BSA to ca. 2.5% for the phenyl group and ca. 6-9% for the butyl group. The ratios of the spin-spin relaxation rate (1/T2) of the free PB to that of the bound PB were ca. 5000-11000 for the butyl group and ca. 23000 for the phenyl group. The binding of PB to BSA was considered to involve primarily the phenyl group.     

Cadmium recovery by a sulfate-reducing magnetotactic bacterium,Desulfovibrio magneticus RS-1, using magnetic separation

Cadmium recovery by a sulfate-reducing magnetotactic bacterium, Desulfovibrio magneticus strain RS-1, was investigated. D. magneticus precipitated >95% of cadmium at an initial concentration of 1.3 ppm in the growth medium. Electron microscopic analysis revealed that D. magneticus formed electron-dense particles on its surface when cultivated in the presence of cadmium ions (Cd²⁺). Sulfide was also found in the precipitate, and the composition ratio of sulfide/cadmium was 0.7. Sixty percent of viable RS-1 cells was recovered by a simple magnetic separation revealing the removal of 58% cadmium from the culture medium.     

Depth profiling of ultra trace metal impurities in polytetrafluoroethylene wares by surface scraping and acid-vapor extraction followed by ICP-MS analysis.

This paper describes the development of the depth profiling method of ultra trace metal impurities in polytetrafluoroethylene (PTFE) wares based on contamination-free sampling followed by acid-vapor extraction and its application to evaluate the washing method for PTFE wares. A contamination-free sampling process was achieved by scraping the surface of PTFE wares with the cleft face of a silicon wafer followed by exposing the PTFE scraped to highly pure acid-vapor. The concentration of metal impurities in extractants was determined by ICP-MS equipped with an electrothermal vaporizer (ETV-ICP-MS). The blank values of Al, Cr, Fe, Ni and Cu by the depth profiling method were 0.006, 0.004, 0.005, 0.002 and 0.003 ng, respectively. By analyzing the depth profile of beakers, the distributions of ultra trace (ng g(-1) level) metal impurities were clarified. An examination of the washing methods by the depth profiling method also clarified that exposing to acid-vapor was more effective than the acid-dipping method for the elimination of metal impurities.     

Application of a new capsule-type silica gel coated with hydrophobic polymer to preparative liquid chromatography on an industrial scale

Summary A new type of column packing material designed for preparative liquid chromatography, silicone polymer-coated silica gel modified with octadecyl group (S/S-C₁₈), was applied to chromatographic purification of a lipophilic biotechnological product. Triglycerides containing γ-linolenic acid were separated from the curde oil that consisted of triglycerides, diglycerides, free fatty acids, sterols and other polar substances, using a S/S-C₁₈ packed column (150 mm I.D. × 1000 mm). No column deterioration was observed after more than 1500 times of sample introductions.     

A Semiconductor Waveguide-Type Optical Frequency Shifter

A waveguide-type optical frequency shifter based on a rotating half-wave plate is proposed. The underlying principle can be used to realize a bit-rate-free and modulation-code-free optical frequency shifter. The waveguide was formed along the ≪1 1 1> direction on a GaAs (1 1 0) substrate by molecular beam epitaxy (MBE) and reactive ion beam etching (RIBE). A 10-MHz optical frequency shift with 16 V_p-p applied voltage and 22.5% shift efficiency is demonstrated.