Chemoselective preparation of ketones by the grignard reaction of N-acylpyrazoles

N-Acylpyrazoles afford chemoselectively the corresponding ketones in good yields by the use of equimolar amounts of Grignard reagent. In the case of an optically active N-acylpyrazole, optical asymmetry was retained in comparable optical yield. Ketone formation by the Grignard reactions can be regarded as an important functionalization in a synthetic loop using pyrazoles as the auxiliary compound.     

Synthesis of monoglucosylated high-mannose-type dodecasaccharide,a putative ligand for molecular chaperone,calnexin, and calreticulin

Convergent and stereoselective synthetic routes to Man9GlcNAc2 (1b), alpha-Glc1M9GlcNAc2 (2b), and its stereoisomer beta-Glc1M9GlcNAc2 (3) were established. Interaction analysis of 2b with CRT was measured by 1H NMR spectroscopy, and the first NMR-based evidence for the specific binding of CRT to 2b was obtained.     

Angular dependence in the transmittance from self‐organized striped pattern of refractive indices in photopolymer

We report on a self‐organized striped pattern of refractive indices in a photopolymer and the resulting angular dependence in the transmittance as a result of the microstructure. The photopolymer plates were obtained by photoreaction of a monomer mixture placed in a space between two glass plates. The monomer mixture was prepared by mixing bifunctional methacrylate monomer, cyanoethylmethacrylate, and 2,4,6‐trimethylbenzoyldiphenylphosphine oxide as photoinitiator. After the photoreaction by uniform irradiation of UV light, the self‐organized striped pattern was observed in the crosslinked photopolymer plate by optical microscopy. Electron probe microanalysis of the cross section of the polymer plate confirms that a compositional inhomogeneity in the medium is quite small. The result suggests that the optically observed striped pattern is not due to the compositional and/or density modulation through the diffusion of monomers. We attribute the striped pattern to the crosslink density modulation and the resulting refractive‐index modulation. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 216–225, 2002     

Properties of Pd---Au and Pt---Cu alloy surfaces for the adsorption and catalytic reduction of O2 and NO by H2

The adsorption and catalytic properties of Pd---Au and Pt---C alloy surfaces were investigated under low pressure conditions, with the real surface composition being monitored using Auger electron spectroscopy. Flash desorption experiments on O₂ and NO, and steady state kinetic experiments involving the reduction of these substances by H₂ were performed on polycrystalline alloy surfaces. For the Pd---Au system, O₂ desorption was promoted by gold, as shown by the shift of O₂ desorption toward lower temperature and a linear decrease in the saturated amount of O₂ adsorption with increase in gold content. For the Pt---Cu system, O₂ desorption was retarded by copper i.e. the O₂ desorption temperature shifted upward with increase in copper content. In both the alloy systems, catalytic activities for the above reactions were significantly suppressed by the addition of gold or copper to the platinum group metals. The drop was more pronounced for NO reduction, suggesting that a larger ensemble of active platinum group metal atoms are necessary for NO dissociation.     

Influence of simulated microgravity on the activation of the small GTPase Rho involved in cytoskeletal formation – molecular cloning and sequencing of bovine leukemia-associated guanine nucleotide exchange factor

Background  

The irregular formation of cytoskeletal fibers in spaceflown experimental cells has been observed, but the disorganization process of fibers is still poorly understood. It is well known that the activation of the small GTPase Rho leads to actin stress fibers assembly. This study was performed to evaluate the effect of simulated microgravity on the activation of Rho that is involved in actin fiber remodeling in cells.     

Preparation of cationic nanoparticles by the particle dissolution method from submicron-sized,styrene-butyl acrylate-dimethylaminoethyl methacrylate terpolymer particles

Cationic nanoparticles were prepared from submicron-sized styrene-butyl acrylate-dimethylaminoethyl methacrylate terpolymer (59.2/20.8/20.0, molar ratio) particles in a polyoxyethylene nonylphenylether nonionic emulsifier aqueous solution at pH 2.0 above 150 °C.     

Elucidation of dominant effect on initial bacterial adhesion onto polymer surfaces prepared by radiation-induced graft polymerization

Surface-modified polyethylene (PE) membrane sheets were prepared by the radiation-induced graft polymerization (RIGP) of an epoxy-group-containing monomer, glycidyl methacrylate (GMA). The epoxy ring of GMA was opened by introducing diethylamine (DEA) or sodium sulfite (SS). We examined the properties of these sheets by measuring the amount of grafting polymer, surface roughness and membrane potential, and also investigated the adhesion of five Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, Pseudomonas fluorescens and Paracoccus denitrificans, onto the prepared sheet surfaces. A linear relationship between the degree of grafting (dg) and surface roughness was observed. Moreover, membrane potential was dependent on the amount of DEA or SS as the ionizable group. These results indicate that RIGP enables the control of the physicochemical properties of such a sheet surface by adjusting dg and the subsequent conversion of functional groups. A batch test on bacterial adhesion onto the sheets clarified that the DEA-containing sheet (DEA sheet) exhibited an adhesion rate constant, k, significantly greater than those of other types of sheet. Clearly, the adhesion rate constant of the DEA sheet increased with dg, indicating that electrostatic interaction is the most decisive factor for bacterial adhesion when it works as an attractive force. Furthermore, the densities of bacteria adhering onto the GMA-containing sheet (GMA sheet) and the SS-containing sheet (SS sheet) were almost the same as that onto a PE sheet, whereas that onto a DEA sheet significantly increased. Thus, the introduction of the GMA- and SS-containing graft chain did not have much influence on bacterial adhesion onto the surfaces, supporting the conclusion that the promotion of bacterial adhesion onto the GMA and SS sheets was due to an increase in surface area resulting from RIGP. Moreover, the scanning electron microscopy images of the sheet surfaces indicate that the conditions and morphologies of initial bacterial adhesion are dependent on surface properties, particularly membrane potential.     

Analysis of the intermolecular interactions between CH3OCH3, CF3OCH3, CF3OCF3, and CH2F2, CHF3

The intermolecular interaction energy curves of CH(3)OCH(3)-CH(2)F(2), CF(3)OCH(3)-CH(2)F(2), CF(3)OCF(3)-CH(2)F(2), CH(3)OCH(3)-CHF(3), CF(3)OCH(3)-CHF(3), and CF(3)OCF(3)-CHF(3) complexes were calculated by the MP2 level ab initio molecular orbital method using the 6-311G** basis set augmented with diffuse polarization functions. We investigate the fluorine substitution effects of both methane and dimethyl ether on intermolecular interactions. In addition, orientation dependence of intermolecular interaction energies is also studied with utilizing eight types of orientations. Our analyses demonstrate that partial fluorinations of methane make electrostatic interaction dominant, and consequently enhance attractive interaction at several specific orientations. On the contrary, fluorine substitutions of dimethyl ether substantially decrease the electrostatic interaction between ether and CH(2)F(2) or CHF(3); thus, there is no such characteristic interaction between the C-H of fluorinated methane and ether oxygen of CF(3)OCF(3) as conventional hydrogen bonding, due to reduced polarity of fluorinated ether. The combination of different pairs of the electrostatic interaction is therefore responsible for the intermolecular interaction differences among the complexes investigated herein and also their orientations.     

Calorimetric study on pure and KOH-doped argon clathrate hydrates

Pure and KOH (x=1.3×10^?3)-doped argon clathrate hydrates were synthesized in an adiabatic high-pressure calorimetric cell from one mole of water and 200 MPa of Ar gas. The heat capacities of the hydrates were measured from 12 to 130 K. No anomaly was found in the pure sample but a glass transition considered to be related to a proton-configurational mode of the host hydrogen-bonded lattice was observed for the first time at 55 K in the doped sample. Comparison with the results on pure and KOH-doped tetrahydrofuran clathrate hydrates indicated that the thermodynamic properties of a hydrogen-bonded system depend on the kind of guest molecule. The heat capacity of argon in the hydrate cages was adequately analyzed with the one-dimensional Pöschl-Teller potential as used in the Ar-β-quinol clathrate and the addivity of heat capacities of the guest and host was shown to be valid in the temperature range 12–130 K.