Polymerization behaviors of racemic and chiral amphiphilic monomers in organized bilayer membranes of lamellar liquid crystalline phase

A racemic amphiphilic monomer, n‐dodecyl glyceryl itaconate (DGI), forms bilayer membranes in water in the presence of small amount of ionic cosurfactant and shows iridescent color. A chiral DGI, S‐DGI, also shows an iridescent property, but with a rather red shift in the color, which can be ascribed to the increased packing density of the monomer in the bilayer membranes. Chrial DGI has a more compact packing density than racemic one owing to closer distance between the monomer molecules; the conversion rate, however, is slower than that of racemic one when H₂O₂ is used as an initiator. When the initiator is changed to an amphiphilic one, 4‐(2‐hydroxyethoxy) phenyl‐(2‐hydroxy‐2‐propyl) ketone (Irgacure 2959), the chiral DGI shows even a little faster conversion rate than that of racemic one. The NMR chemical shift results of protons in benzene ring show that the molecules of Irgacure 2959 insert into the bilayer membranes. The molecular weights of the corresponding polymers prove that the initiation by H₂O₂ is restricted compared to that by Irgacure 2959. It is concluded that the decelerated polymerization behavior of chiral DGI initiated by H₂O₂ is a result of limited diffusion of the initiator into the lamellar bilayer structures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4891–4900, 2007     

Simultaneous determination of serotonin and 5-hydroxyindole-3-acetic acid in human urine by automated precolumn derivatization and semi-microbore column liquid chromatography with fluorescence detection.

An improved high-performance liquid-chromatographic (HPLC) assay for the simultaneous determination of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in human urine is reported. Following the automated precolumn derivatization of urinary 5-HT and 5-HIAA with benzylamine, the derivatives are separated by isocratic elution on a reversed-phase C18 semi-microbore column, and are fluorometrically detected at an excitation wavelength of 345 nm and an emission wavelength of 480 nm. The detection limits of 5-HT and 5-HIAA are 7 and 5 nmol/l in urine (0.7 and 0.5 fmol/20-microl injection). The proposed automatic method permits a highly selective and sensitive determination of 5-HT and 5-HIAA in human urine without any sample purification.     

A simple and sensitive method for the determination of hydroxylamine in fresh-water samples using hypochlorite followed by gas chromatography.

A new and simple method for the determination of hydroxylamine in environmental water, such as fresh rivers and lakes using hypochlorite, followed by its gas choromatographic detection, has been developed. A glass vial filled with sample water was sealed by a butyl-rubber stopper and aluminum cap without head-space, and then sodium hypochlorite solution was injected into the vial through a syringe to convert hydroxylamine to nitrous oxide. The head-space in the glass vial was prepared with 99.9% grade N2 using a gas-tight syringe. After the glass vial was shaken for a few minutes, nitrous oxide in the gas-phase was measured by a gas chromatograph with an electron-capture detector. The dissolved nitrous oxide in the liquid-phase was calculated according to the solubility formula. The proposed method was applied to the analysis of fresh-water samples taken from Iu river and Hii river, flowing into brackish Lakes Nakaumi and Shinji, respectively.     

Endoscopic Observation of Tissue by Narrowband Illumination

We propose a new illumination method for a medical endoscope: narrow band imaging (NBI), in which the spectral bandwidth of the filtered light is narrowed. To confirm how the spectral specifications of the filtered light influence a reproduced image, an experiment was conducted observing the endoscopic images of the back mucosa of a human tongue. In addition, the effect of NBI on endoscopic images was investigated through preliminary clinical tests in colonoscopy and upper gastrointestinal endoscopy. It has been shown that NBI can enhance the capillary pattern and the crypt pattern on the mucosa. These patterns are useful features for diagnosing an early cancer.     

A fast atom bombardment mass spectrometric analysis of crown ether complexes [1]

Analyses of crown ether complexes of alkali metal ions and characterization of the complexes formed inm-nitrobenzyl alcohol have been carried out by fast atom bombardment (FAB) mass spectrometry. By using m-nitrobenzyl alcohol as a matrix for measurements, the stoichiometry of the complexes was assessed on the basis of the observed FAB peaks. In addition, the formation of crown ether-alkali metal complexes at a 2 : 1 molar ratio was enhanced by increasing the ionic radius of the metal ion in agreement with previous observations. On these grounds, FAB mass spectrometry may provide a rapid means for investigation of the complexation behavior of crown ethers and the stoichiometry of the complexes.     

High-performance liquid chromatographic method for determining trichothecene mycotoxins by post-column fluorescence derivatization

The method described here is based on a separation of deoxynivalenol, nivalenol and fusarenon-X on a C18 column using aqueous acetonitrile, and successive post-column fluorescence derivatization involving an alkaline decomposition to form formaldehyde and modified Hantzsch reaction with methyl acetoacetate and ammonium acetate (lambda ex = 370 nm and lambda em = 460 nm). By this method, 5-10 ng of the standard trichothecenes could be determined. By employing a clean-up procedure with a florisil column and a Sep-Pak CN cartridge, 61.4-96.9% recoveries were obtained for deoxynivalenol and nivalenol added to corn, wheat and barley at concentration levels of 0.05-1 ppm.