Preparation of monodisperse SiO2 nanoparticles by membrane emulsification using ideally ordered anodic porous alumina

Monodisperse SiO2 particles of nanometer dimensions were fabricated by membrane emulsification using ideally ordered anodic porous alumina. For the preparation of monodisperse emulsion droplets, the dispersed phase was pressed through a porous alumina membrane into the continuous phase. After solidification treatment of the emulsion droplets, prepared spherical SiO2 nanoparticles with uniform sizes were obtained. From scanning electron microscope observation of the obtained particles, it was confirmed that the size distribution of SiO2 nanoparticles is relatively narrow.     

Thermal analysis graphite intercalation compounds with dichlorides of some d-elements: A.S. Skoropanov,G.S. Petrov,A.A. Vecher,Yu.N. Novikov and M.E. Vol'pin,Thermochim. Acta, 90 (1985) 339-342

Kinetic and thermodynamic aspects of the axial base dissociation of solid Co(salen) (X-py) complexes, X = H (1), 3-Me (2), 4-Me (3), 3,4-Me₂ (4), 3,5-Me₂ (5), 3-NH₂ (6), 3-Cl (7), 3-CN (8), 4-CN (9), have been investigated by means of TG-DSC and isothermal weight-loss measurements. These adducts endothermically dissociate the axial base giving rise to the oxygen-active Co(salen) complex. The axial base dissociation reactions fit the contracting disc equation and the kinetic compensation effect is observed for all the adducts excepting Adducts 4–6. For the remaining adducts the kinetic and thermodynamic stabilities of the Co-(X-py) bond are found to increase linearly with increasing Hammett's substitution constants of X except for Adducts 3 and 9. These results are discussed in terms of the σ and π interactions between cobalt(II) and substituted pyridine. Factors dominating the kinetic bond stability are briefly discussed.     

Measurements of equilibrium water vapor pressures for the dehydration of magnesium, manganese and cobalt formate dihydrates by means of the transpiration method

The equilibrium water vapor pressures for the thermal dehydration of Mg(HCO(2))(2). 2H(2)O, Mn(HCO(2))(2). 2H(2)O and Co(HCO(2))(2). 2H(2)O were measured by means of the transpiration method. These hydrates form isomorphous crystals with space group P21/c. In this structure, the water molecules lie in the planes parallel to the (100) planes. Thermodynamic data such as DeltaG, DeltaH and DeltaS were derived from the values of the water vapor pressures. The relationship between these thermodynamic data and the crystal structures is discussed.     

Phlomisflavosides A and B, new flavonol bisglycosides from Phlomis spinidens

From the aerial parts of Phlomis spinidens, two new flavonol bisglycosides, phlomisflavosides A (1) and B (2), were isolated together with the known compounds, astragalin, isoquercitrin, lamiridoside, phlomoside A, shanzhiside methyl ester, 8-O-acetylshanzhiside methyl ester, phlorigidoside C, rodioloside (=salidroside), forsythoside B, citroside A and lariciresinol-4'-O-beta-D-glucoside. The structures of the new compounds were elucidated based on spectral and chemical evidence.     

Effect of substituent on the enantioselectivity for lipase-catalyzed kinetic resolution of glycerol derivatives

The lipase-catalyzed transesterifications of various substituted diphenyl 1,2-ketals of glycerol have been investigated. Efficient modification of the substrate structure with bis(4-bromophenyl) ketal was found to enhance the enantioselectivity up to E=57 at 0 °C.     

Polymerization of silylacetylenes by W and Mo catalysts

Polymerization of HC?CSiMe₃ homologues (HC?CSiMe₂R; R = n-C₆H₁₃, CH₂CH₂Ph, CH₂Ph, Ph, and t-Bu) was studied by use of W and Mo catalysts. W catalysts provided polymers in good yields from all these monomers. Mo catalysts gave mainly a polymer from HC?CSiMe₂–t-Bu, but virturally only cyclotrimers from sterically less croweded monomers (R = n-C₆H₁₃, CH₂CH₂Ph, CH₂Ph, and Ph). Polymers with flexible R groups (n-C₆H₁₃, CH₂CH₂Ph, and CH₂Ph) were totally soluble, their number-average molecular weights being 7000–18,000. Polymers with inflexible R groups (Ph and t-Bu) were partly insoluble. Every polymer was a yellow rubber or powder, and had the structure, \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH} = {\rm C}\left( {{\rm SiMe}_{\rm 2} {\rm R}} \right)\rlap{--} ]_n $\end{document}. The results were compared with the polymerization and polymer of HC?CSiMe₃.     

Infrared spectra of the water-nitrogen complexes (H2O)2-(N2)n(n = 1-4) in argon matrices

The infrared spectra of the water-nitrogen complexes trapped in argon matrices have been studied with Fourier transform infrared absorption spectroscopy. The absorption lines of the H20-N2 1:1, 1:2, 1:n, and 2:1 complexes have been confirmed on the basis of the concentration effects. In addition, we have observed a few lines and propose the assignments for the 2:2, 2:3, and 2:4 complexes in the nu1 symmetric stretching and nu2 bending regions of the proton-acceptor molecule, and in the bonded OH stretching region of the proton-donor molecule. The redshifts in the bonded OH stretching mode and blueshifts in the OH bending mode suggest that the hydrogen bonds in the (H2O)2-(N2)n complexes with n = 1-4 are strengthened by the cooperative effects compared to the pure H2O dimer. Two absorption bands due to the 3:n complexes are also observed near the bonded OH stretching region of the H2O trimer.     

Improvement of culture conditions forl-proline production by a recombinant strain ofSerratia marcescens

Serratia marcescens SP511 was previously reported to be anl-proline-producing strain that harbors a recombinant plasmid carrying the mutant type of the proline operon. This strain produced 65 g/L ofl-proline in a medium containing 22% sucrose and urea after 5 d of incubation under the conventional culture conditions. We searched for more suitable culture conditions for more abundantl-proline production by SP511. To improve the supply of a nitrogen source to cells, ammonium was used instead of urea and fed to a culture under control of the pH of the medium. The concentrations of MgSO₄ and K₂HPO₄ were increased, and in addition, sucrose was continuously added to the culture at a final concentration of 32%. Under these conditions, the cell amount was increased twofold over that under the previous conditions andl-proline production reached a maximum of more than 100 g/L after 4 d of incubation.