Simultaneous separation of water‐ and fat‐soluble vitamins in isocratic pressure‐assisted capillary electrochromatography using a methacrylate‐based monolithic column

A method of simultaneous separation of water‐ and fat‐soluble vitamins using pressure‐assisted CEC with a methacrylate‐based capillary monolithic column was developed. In the proposed method, water‐soluble vitamins were mainly separated electrophoretically, while fat soluble‐ones were separated chromatographically by the interaction with a methacrylate‐based monolith. A mixture of six water‐soluble and four fat‐soluble vitamins was separated simultaneously within 20 min with an isocratic elution using 1 M formic acid (pH 1.9)/acetonitrile (30:70, v/v) containing 10 mM ammonium formate as a mobile phase. When the method was applied to a commercial multivitamin tablet and a spiked one, the vitamins were successfully analyzed, and no influence of the matrix contained in the tablet was observed.     

Polymerization of 1,3‐dienes with functional groups. II. Free‐radical polymerization of N‐(2‐methylene‐3‐butenoyl)piperidine

The free‐radical homopolymerization and copolymerization behavior of N‐(2‐methylene‐3‐butenoyl)piperidine was investigated. When the monomer was heated in bulk at 60 °C for 25 h without an initiator, about 30% of the monomer was consumed by the thermal polymerization and the Diels–Alder reaction. No such side reaction was observed when the polymerization was carried out in a benzene solution with 1 mol % 2,2′‐azobisisobutylonitrile (AIBN) as an initiator. The polymerization rate equation was found to be R_p ∝ [AIBN]^0.507[M]^1.04, and the overall activation energy of polymerization was calculated to be 89.5 kJ/mol. The microstructure of the resulting polymer was exclusively a 1,4‐structure that included both 1,4‐E and 1,4‐Z configurations. The copolymerizations of this monomer with styrene and/or chloroprene as comonomers were carried out in benzene solutions at 60 °C with AIBN as an initiator. In the copolymerization with styrene, the monomer reactivity ratios were r₁ = 6.10 and r₂ = 0.03, and the Q and e values were calculated to be 10.8 and 0.45, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1545–1552, 2003     

Hydrogen/deuterium adsorption and absorption properties on and in palladium using a combined plane wave and localized basis set method

Detailed information on the H/D isotope effects for adsorption on the surface and absorption in the bulk is important for understanding the nuclear quantum effect. To achieve this, we developed a new theoretical approach, namely, the combined plane wave and localized basis set (CPLB) method. By using the multicomponent quantum chemical method, which takes into account the quantum effect of a proton or deuteron, with the localized part of the CPLB method, direct analysis of the H/D isotope effect about adsorption and absorption is carried out. In this study, we performed a theoretical investigation of the H/D isotope effects for adsorption on a Pd(111) surface and absorption in bulk Pd. We clearly showed an H/D isotope effect on geometry during adsorption and absorption. Our developed CPLB approach is a powerful tool for analyzing the quantum nature of H/D in surface, bulk, and inhomogeneous systems.     

Shock‐tube and modeling study of acetaldehyde pyrolysis and oxidation

Pyrolysis and oxidation of acetaldehyde were studied behind reflected shock waves in the temperature range 1000–1700 K at total pressures between 1.2 and 2.8 atm. The study was carried out using the following methods, (1) time‐resolved IR‐laser absorption at 3.39 μm for acetaldehyde decay and CH‐compound formation rates, (2) time‐resolved UV absorption at 200 nm for CH₂CO and C₂H₄ product formation rates, (3) time‐resolved UV absorption at 216 nm for CH₃ formation rates, (4) time‐resolved UV absorption at 306.7 nm for OH radical formation rate, (5) time‐resolved IR emission at 4.24 μm for the CO₂ formation rate, (6) time‐resolved IR emission at 4.68 μm for the CO and CH₂CO formation rate, and (7) a single‐pulse technique for product yields. From a computer‐simulation study, a 178‐reaction mechanism that could satisfactorily model all of our data was constructed using new reactions, CH₃CHO (+M) → CH₄ + CO (+M), CH₃CHO (+M) → CH₂CO + H₂(+M), H + CH₃CHO → CH₂CHO + H₂, CH₃ + CH₃CHO → CH₂CHO + CH₄, O₂ + CH₃CHO → CH₂CHO + HO₂, O + CH₃CHO → CH₂CHO + OH, OH + CH₃CHO → CH₂CHO + H₂O, HO₂ + CH₃CHO → CH₂CHO + H₂O₂, having assumed or evaluated rate constants. The submechanisms of methane, ethylene, ethane, formaldehyde, and ketene were found to play an important role in acetaldehyde oxidation. © 2007 Wiley Periodicals, Inc. 40: 73–102, 2008     

Basic design and synthesis of sulfonated contrast agents for magnetic resonance imaging based on gadolinium complexes.

Magnetic resonance angiography (MRA) is an imaging method to examine blood vessels based on the magnetic resonance imaging (MRI) technique. For this purpose, blood pool contrast agents have been developed to selectively increase the signal intensity of the intravascular lumen for improvement of the contrast-to-noise ratio in MR images. Here, we describe the design and the syntheses of six novel sulfonated contrast agents (KMR-Sulfo1 - 6), their chemical properties and their in vivo applications. In this study, we investigated the lipophilicity and the hydrophilicity of a gadolinium complex using a convenient two-step synthesis route, with the goal of prolonging the plasma half-life by binding mainly to human serum albumin. We confirmed that KMR-Sulfo5 fulfilled the requirements as a blood pool contrast agent: it showed a sufficient relaxivity r(1) of 5.9 mM(-1) s(-1), a long plasma half-life of 25.7 min and complete elimination from the body within 12 h after the administration.     

Multielement determination of trace metals in river water (certified reference material, JSAC 0301-1) by high efficiency nebulization ICP-MS after 100-fold preconcentration with a chelating resin-packed minicolumn.

The determination of 34 trace metals in a river water certified reference material (CRM), i.e. JSAC 0301-1, which was issued by the Japan Society for Analytical Chemistry in January 2004, was performed by ICP-MS with a high efficiency nebulizer after preconcentration with a laboratory-made chelating resin-packed minicolumn, with which trace metals were concentrated 100-fold from 50 mL of a river water sample to 0.5 mL of the final analysis solution. Trace metals in JSAC 0301-1 were observed in the concentration range from 19 microg L(-1) of Al to 0.000053 microg L(-1) of Bi. It was found that most of the concentrations of trace metals, including rare earth elements (REEs), in JSAC 0301-1 were lower than those in JAC 0031, which was also a previously issued CRM prepared with water from the same river as that of JSAC 0301-1. The low concentrations of trace metals in JSAC 0301-1 might be attributed to the fact that there was a heavy rain before collecting the original water sample to prepare the present CRM. Furthermore, the REE distribution patterns of JSAC 0301-1, JAC 0031 and the average values of river water samples in Japan were parallel to each other. These results indicate that the distributions of REEs in JSAC 0301-1 and JAC 0031 were the typical ones of river water samples in Japan.     

43 Gbit/s x 54 ch Transmission with Dense 75 GHz Channel Spacing in NRZ Modulation Scheme

We demonstrated 2.16-Tbit/s (43 Gbit/s x 54 ch) WDM transmission over 600 km of standard single-mode fiber with high spectral efficiency 0.53 bit/s/Hz using optimized optical mux/demux filters for 75-GHz channel spacing in a simple NRZ modulation scheme.