Formation and Characterization of Reversed Micelles Composed of Phospholipids and Fatty Acids

The formation of reversed micellar systems composed of phosphatidylcholine (PC) and fatty acid was newly demonstrated by a significant increase in water content in the organic ethyl oleate phase when the micelles were prepared by the contact method. The solubilized water concentration in the reversed micellar organic phase reached 3 wt%. The new systems are expected to be used as highly biocompatible reversed micellar systems. The structure of the reversed micelles composed of PC and oleic acid was characterized by determining the water concentration and by small-angle X-ray scattering analysis. The reversed micelles composed of PC and oleic acid formed in ethyl oleate were spherical. The radius of gyration was between 30 and 50 Å. The size of the reversed micelles decreased with an increase in the oleic acid concentration and was independent of the PC concentration. Experimental results indicated that the structure of the reversed micellar system was determined by the oleic acid concentration. An increase in the PC concentration caused an increase in the number of reversed micelles of the same size. These reversed micellar systems are expected to be used as solubilization media in pharmaceutical and food industries because they are not toxic.     

Fabrication of high performance Gd–Ba–Cu–O single grains in air using a practical melt processing technique

A practical processing route for the fabrication of LRE-Ba–Cu–O single grain superconductors has been developed at the University of Cambridge based on a generic, Mg-doped Nd-123 melt textured seed and suppression of the formation of the solid solution phase in air by enriching the precursors with higher Ba concentration. The processing of high performance Gd–Ba–Cu–O single grains using this processing route is described. The Mg-doped generic seed crystal has been used effectively to promote heterogeneous nucleation via a cold-seeding process. The Gd/Ba solid solution has been suppressed by enriching Gd–Ba–Cu–O precursor powders with two different Ba-rich compositions. This involved adding BaO₂ and GdBa₆Cu₃O_y (Gd-163) (a novel Ba-rich second phase) to the precursor powders, respectively. The Gd-163 phase has been observed not only to suppress formation of the solid solution phase, but also to promote increased heterogeneous grain size. A detailed further study has been carried out with an initial aim of optimizing the BaO₂ and Gd-163 phase content of the precursor composition to produce a single grain almost free of solid solution. Based on the optimized parameters, large single grain Gd–Ba–Cu–O superconductors have been fabricated in an air atmosphere and demonstrated to exhibit record trapped magnetic fields for this material melt processed in air in relatively small single grain samples. The trapped fields of samples produced in air atmosphere are at least comparable to those processed under reduced oxygen partial pressure.     

Highly refractive polymer resin derived from sulfur‐containing aromatic acrylate

New sulfur‐containing polymers with high‐refractive indices and low birefringences have been developed as UV‐curable high‐refractive polymer resins. The polymers derived from 2,7‐bis[(2‐acryloylethyl)sulfanyl]thianthrene (2,7‐BAST) and 4,4′‐bis[(acryloyloxyethylthio)diphenylsulfide (4,4′‐BADS) were prepared by photopolymerization under UV irradiation. Transparent UV‐cured films were obtained in both cases. Both polymers showed good thermal stability, such as a 5% weight‐loss temperature at 355 °C under nitrogen and glass transition temperatures (T_g) in the range of 94–143 °C. They also showed high‐refractive indices of 1.6531 and 1.6645 at 632.8 nm and low birefringences of 0.0039 and 0.0069 in addition to high transparency in the visible region. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2604–2609, 2010     

Intramolecular Friedel-Crafts type reaction of vinyloxiranes linked to an ester group

The 7-endo Friedel-Crafts cyclization of arylpropyl vinyloxiranes was found to proceed regio- and stereoselectively to afford polyfunctional seven-membered carbocycles in excellent yields.     

Repetitive spectral subtraction method for the spectrophotometric determination of rare earth elements

Summary A new multiwavelength data-analysis method for the determination of multicomponent mixtures, the repetitive spectral subtraction method (RSSM), is proposed. In RSSM, spectral data are obtained at evenly spaced wavelengths in the range of interest, and the analysis of the spectrum is performed as repetitive determination-subtraction cycle. In the determination step, the series of data in the narrow wavelength range is used, which is specified as to include the most characteristic or the largest peak for each component. Assuming a linear background, the target component, which can be a small group of components, is simultaneously determined together with co-existing components. In the next subtraction step, the calculated contribution of the component is subtracted from the spectral data in the whole measured wavelength range, and the component is assigned as determined and is excluded from the following analysis. This determination-subtraction cycle is repeated until all the components are determined.With RSSM, a mixture of many components can be precisely determined by the use of most information contained in the spectrum. The accuracy of determination can be improved by automatic estimation of the background and the gradual decrease of interferences. In order to demonstrate the usefulness of RSSM, the 8 rare earth elements (Pr, Nd, Sm, Eu, Dy, Ho, Er, Tm) in the model mixtures were determined by spectrophotometry, and the results were compared with those of the usual correction factor method and the derivative method. Furthermore, the 8 rare earth elements were determined in ores, monazite and xenotime.

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Spektralphotometrische Bestimmung von Seltenen Erden mit Hilfe eines Verfahrens der wiederholten Subtraktion