Determination of Hg isotopic compositions in certified reference material NIES No. 13 Human Hair by cold vapor generation multi-collector inductively coupled plasma mass spectrometry

Hg isotopic ratios of NIES CRM No. 13 Human Hair were analyzed using cold vapor generation coupled to multi-collector inductively coupled plasma mass spectrometer to meet the growing demand for better understanding of Hg exposure routes by using Hg isotopic compositions in human hair samples. To validate and assure the accuracy of our analytical method, (1) the reproducibility of the Hg isotopic measurement was monitored and (2) the Hg isotopic compositions of four secondary reference materials—IAEA-085, IAEA-086, and CRPG-RL24H—were measured. Our results for NIES CRM No. 13 show the mass-dependent fractionation values of δ ¹⁹⁹Hg = (2.13 ± 0.07) ‰, δ ²⁰⁰Hg = (0.98 ± 0.08) ‰, δ ²⁰¹Hg = (2.77 ± 0.10) ‰, δ ²⁰²Hg = (1.89 ± 0.10) ‰, and δ ²⁰⁴Hg = (2.76 ± 0.16) ‰ (2SD, n = 11) and the mass-independent fractionation values of Δ ¹⁹⁹Hg = (1.65 ± 0.06) ‰, Δ ²⁰⁰Hg = (0.04 ± 0.04) ‰, Δ ²⁰¹Hg = (1.36 ± 0.07) ‰, and Δ ²⁰⁴Hg = (?0.04 ± 0.11) ‰ (2SD, n = 11). Interlaboratory comparison of the CRM performed at the University of Pau showed good agreement with the values obtained at NIES.     

Stereospecific analysis of loxoprofen in plasma by chiral column liquid chromatography with a circular dichroism-based detector

The chiral separation of loxoprofen was achieved on a chiral column with UV and circular dichroism (CD) detection. The good resolution of four loxoprofen stereoisomers was obtained. The column used for the chiral separation was Chiralcel OJ column (250 x 4.6 mm) using hexane-2-propanol-trifluoroacetic acid (95:5:0.1), as an eluent. The flow-rate was 1.0 ml/min and the detection was at 225 nm. In addition, CD and UV spectra were obtained by stopped flow scanning. The method allows the determination of the stereoisomers of loxoprofen in human plasma after the administration of therapeutic dose of the racemic drug, thus HPLC with CD detector is useful for the stereospecific determination of loxoprofen products in biological samples.     

Preparation of highly potent and selective non-peptide antagonists of the arginine vasopressin V1A receptor by introduction of a 2-ethyl-1H-1-imidazolyl group

To find a new series of arginine vasopressin (AVP) V1A receptor antagonists, the influence of the 2-phenyl group of 2-phenyl-4'-[(2,3,4,5-tetrahydro-1H-1-benzazepin-1-yl)carbonyl]benzanilide (7) was investigated. Replacement of the 2-phenyl group by a 2-ethyl-1H-imidazol-1-yl group was effective in yielding a V1A-selective compound. Moreover, this imidazolyl group was introduced in the same position in YM-35471 (6), and further studies of these compounds were performed. Consequently, we found that the (Z)-4'-({4,4-difluoro-5-[(N-cyclopropylcarbamoyl)methylene]-2,3,4,5-tetrahydro-1H-1-benzazepin-1-yl}carbonyl)-2-(2-ethyl-1H-1-imidazol-1-yl)benzanilide (9f) exhibited highly potent affinity and selectivity, and was the most potent antagonist for the V1A receptor among our compounds. The synthesis and pharmacological evaluation of these compounds are described in this paper.     

Non-covalent switch for intramolecular energy transfer

The axially coordinated complex of phenylazopyridine and a Zn-porphyrin/free-base porphyrin conjugate provides a switch for intramolecular energy transfer, with reversible complexation/decomplexation as a switching protocol.     

Synthesis of nylon 6–clay hybrid by montmorillonite intercalated with ϵ-caprolactam

It was found that montmorillonite was intercalated with ?-caprolactam. X-ray diffraction revealed that the chain axes of the ?-caprolactam were parallel to the montmorillonite plates. The intercalated montmorillonite was swollen by molten ?-caprolactam at 200°C. ?-Caprolactam and 6-aminocaproic acid (accelerator) were polymerized with the intercalated montmorillonite at 260°C for 6 h, yielding a nylon 6-clay hybrid. X-ray diffraction and transmission electron micrography revealed that the silicate layers of the hybrid were uniformly dispersed in the nylon 6 matrix. Mechanical properties of the hybrid were improved. The strength and the modulus of the hybrid increased compared with the previously reported nylon 6 clay-hybrid (NCH) synthesized by montmorillonite intercalated with 12-aminolauric acid. The heat distortion temperature (HDT) of the hybrid was 164°C, which was 12°C higher than that of NCH. © 1993 John Wiley & Sons, Inc.     

Morphological and spectroscopic properties of thin films of self-assembling amphiphilic porphyrins on a hydrophilic surface as revealed by scanning near-field optical microscopy

We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties.     

Hexagonal columnar porphyrin assembly by unique trimeric complexation of a porphyrin dimer with pi-pi stacking: remarkable thermal behavior in a solid

On heating, syn-diporphyrin zinc complexes fused with bis(ethano)dimethoxyanthracene, the crystal structure of which showed a unique trimeric assembly, extruded one ethylene molecule at 240-310 degrees C to give a porphyrin-naphthoporphyrin diad, and the second retro-Diels-Alder reaction and concomitant decomposition of the methoxy groups occurred at 280-350 degrees C to give the anthraquinone-fused diporphyrin, while the first thermal conversion of the anti-diporphyrin zinc complex occurred in a much lower temperature range (180-230 degrees C).     

Glycosides of Atractylodes lancea

Five sesquiterpenoid glycosides (two guaiane-type glycosides and three eudesmane-type glucosides) and a glucoside of an acetylene derivative were newly isolated from the water-soluble portion of the methanolic extract of Atractylodes lancea rhizome together with 26 known compounds. Their structures were characterized as atractyloside A 14-O-beta-D-fructofuranoside, (1S,4S,5S,7R,10S)-10,11,14-trihydroxyguai-3-one 11-O-beta-D-glucopyranoside, (5R,7R,10S)-isopterocarpolone beta-D-glucopyranoside, cis-atractyloside I, (2R,3R,5R,7R,10S)-atractyloside G 2-O-beta-D-glucopyranoside, and (2E,8E)-2,8-decadiene-4,6-diyne-1,10-diol 1-O-beta-D-glucopyranoside on the basis of chemical and spectroscopic investigation. The presence of six characteristic guaiane-type glucosides in both rhizomes of A. lancea and Atractylodes japonica suggested a close chemotaxonomic relationship between them.     

Radiation-induced chemical evolution of biomolecules

Chemical evolution in glycilglycine (Gly2) films irradiated with 146 nm vacuum ultraviolet light was studied. It is found that quantum efficiency of chemical evolution from Gly2 to glycilglycilglycine (Gly3) is smaller than that to glycilglycilglycilglycine (Gly4) due to the multiple step of reaction. Furthermore, we have carried out measurement of soft X-ray natural circular dichroism spectra for serine and alanine films in the energy region of oxygen 1s transition and we report the splitting of 1s→π* transitions.