Synthesis of iron—cobalt ultrafine particles by decomposition of Fe(CO)5---Co(CO)3NO using a TEA CO2 laser

Ultrafine particles of iron—cobalt alloy were synthesized and isolated at room temperature in a maximum yield of 90% by the dielectric breakdown of a mixture of Fe(CO)₅ (5 Torr) and Co(CO)₃NO (0.5 Torr) on irradiation with a tightly-focused laser beam of a transversely-excited-atmospheric (TEA) CO₂ laser. CO and NO are also obtained as volatile products. Transmission electron micrographs of the iron-cobalt particles show the existence of fine and well-organized spherical particles. The distribution of the particle size is relatively uniform in the range 6–9 nm with a mean particle size of 8 nm. In X-ray diffractometry, the ultrafine particles are found to be mainly f.c.c. γ-iron—cobalt alloy which is normally stable in the range 1183–1234 K to 1673–1773 K. The b.c.c. -iron—cobalt, iron oxides and cobalt oxides are observed as minor products (γ-iron—cobalt to iron---cobalt OXIDES=8:1:1). The ratio of iron and cobalt atoms in the particles can be changed by changing the mixture of Fe(CO)₅ and Co(CO)₃NO. The ratio of γ-iron—cobalt to -iron—cobalt to iron—cobalt oxide also depends on the ratio of iron and cobalt atoms in the particles.     

An improved method for acetaldehyde determination in blood by high-performance liquid chromatography and solid-phase extraction

This study reports on an improved method for acetaldehyde (ACH) determination in blood by high-performance liquid chromatography (HPLC). In the case of HPLC analysis, ACH is generally converted to derivatives for ultraviolet detection (for example 2,4-dinitrophenylhydrazine [DNPH] derivative). Nevertheless, elevation of the background during protein precipitation, hydrazone synthesis, or both frequently results in a serious loss of accuracy and precision of the analysis. The method in this study is developed to minimize the increase in nonspecific ACH-DNPH with a view to optimize mainly the synthetic condition of ACH-DNPH. The background is decreased dramatically by gentle deproteination, optimization of the DNPH amount and reaction pH, and reversed-phase solid extraction for the elimination of excess DNPH reagent. The standard curves show good linearity between 0 and 100 microM and minimal background is observed, indicating that the method is useful for monitoring the ACH concentration in blood.     

Formation and metabolism of pungent principle of Capsicum fruits. XV. Microdetermination of capsaicin by high-performance liquid chromatography with electrochemical detection

A new, highly sensitive method for quantitative separation and determination of capsaicin and dihydrocapsaicin by high-performance liquid chromatography with electrochemical detection is elaborated. The method employs a Cosmosil 5Ph column eluted with 100 mM potassium dihydrogenphosphate containing 45% acetonitrile (pH 5.0) at a flow-rate of 1.0 ml/min, and an electrochemical detector (at a potential of +750 mV versus the Ag/AgCl electrode). The detection limits for both capsaicin and dihydrocapsaicin were 12 pg (39 fmol) at a signal-to-noise ratio of 3:1. By applying this method, the biological half-life of capsaicin in the rat was investigated.     

High-temperature gas-chromatography of some inorganic chlorides

Summary Electric-conductivity detector is used successfully for the detection of inorganic chlorides in high temperature gas chromatography (450–1000°C). Following mixtures can be separated by the carrier gas He (60 ml/min) on a 250 mm Pt-column with the packing constructed of a fused salt and Chromosorb WAW: BeCl₂/AlCl₃at 560°C; PbCl₂/SnCl₂at 780°C; BiCl₃/SbCl₃at 660°C; BiCl₃/PbCl₂ at 560°C; TlCl/FeCl₃, TlCl/BeCl₂, TlCl/AlCl₃, ThCl₄/AlCl₃ at 640°C; InCl₃/(AlCl₃+FeCl₃) at 660°C; ZnCl₂/PbCl₂ at 780°C; SnCl₂/(NaCl+KCl) at 830°C; and TlCl/PbCl₂ at 830°C.

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Hochtemperatur-Gas-Chromatographie einiger anorganischer Chloride

Zusammenfassung Zum Nachweis anorganischer Chloride bei der Hochtemperatur-Gas-Chromatographie (450–1000°C) wird mit gutem Erfolg ein Leitfähigkeitsdetektor verwendet. Es wird eine 250 mm-Pt-Säule benutzt, gefüllt mit einem geschmolzenen Salz (Alkaki oder Erd-alkalichloride) auf Chromosorb WAW. Als Trägergas dient Helium (60 ml/min). Folgende Gemische können getrennt werden: BeCl₂/AlCl₃ bei 560°C; PbCl₂/SnCl₂ bei 780°C; BiCl₃/SbCl₃ bei 660°C; BiCl₃/PbCl₂ bei 560°C; TlCl/FeCl₃, TlCl/BeCl₂, TlCl/AlCl₃, ThCl₄/AlCl₃ bei 640°C; InCl₃/(AlCl₃ + FeCl₃) bei 660°C; ZnCl₂/PbCl₂ bei 780°C; SnCl₂/(NaCl+KCl) bei 830°C; TlCl/PbCl₂ bei 830°C.

     

Temperature dependence on the binding of butyl orange by bovine serum albumin: The effect of urea

The effect of urea on the extent of the binding of butyl orange by bovine serum albumin has been examined by an equilibrium dialysis method. The first binding constants and the thermodynamic parameters for the formation of the first dye anion–protein complex have been calculated. Addition of urea to the binding system causes a marked decrease in the absolute magnitude of the free energy change. The enthalpy change during binding becomes more exothermic, and the entropy change tends to decrease with increasing concentration of urea. These results can be interpreted in terms of the concept that urea reduces the structure of the aqueous environment and hence lowers the tendency of apolar groups of the dye and the albumin to participate in the formation of hydrophobic interactions.     

Nakinadines B-F: new pyridine alkaloids with a β-amino acid moiety from sponge Amphimedon sp.

Five new 3-alkylpyridine alkaloids with a β-amino acid moiety, nakinadines B-F (1-5), have been isolated from an Okinawan marine sponge Amphimedon sp. (SS-1059), and the structures and stereochemistry were elucidated by spectroscopic data. Nakinadines B (1) and C (2) showed modest cytotoxicity.     

Stereoselective hydrothiolation of alkynes catalyzed by cesium base: facile access to (Z)-1-alkenyl sulfides

Treatment of alkyne with alkanethiol in the presence of a catalytic amount of cesium carbonate and a radical inhibitor in DMSO provides the corresponding adduct, (Z)-1-alkenyl alkyl sulfide, in good yield with high selectivity.     

Momentum dependence of charge excitations in the electron-doped superconductor Nd1.85 Ce0.15 CuO4: a resonant inelastic x-ray scattering study

We report a resonant inelastic x-ray scattering (RIXS) study of charge excitations in the electron-doped high-T(c) superconductor Nd1.85 Ce0.15 CuO4. The intraband and interband excitations across the Fermi energy are separated for the first time by tuning the experimental conditions properly to measure charge excitations at low energy. A dispersion relation with q-dependent width emerges clearly in the intraband excitation, while the intensity of the interband excitation is concentrated around 2 eV near the zone center. The experimental results are consistent with theoretical calculation of the RIXS spectra based on the Hubbard model.