NO reduction by C3H6 over apatite-type A10(PO4)6(OH)2 (A?=?Ca and Sr)-supported Pt catalysts

A₁₀(PO₄)₆(OH)₂ (A = Ca and Sr)-supported Pt catalysts were prepared and their catalytic activity in NO reduction were investigated. The Sr₁₀(PO₄)₆(OH)₂-supported catalyst had high catalytic activity in the C₃H₆?CNO?CO₂ reaction; the activity was higher than that of the ??-Al₂O₃-supported catalyst at 300 °C. The basicity of the apatite supports would affect the chemical state of Pt on catalyst, resulting in promotion of NO reduction.     

Confinement in carbon nanospace-induced production of KI nanocrystals of high-pressure phase

An outstanding compression function for materials preparation exhibited by nanospaces of single-walled carbon nanohorns (SWCNHs) was studied using the B1-to-B2 solid phase transition of KI crystals at 1.9 GPa. High-resolution transmission electron microscopy and synchrotron X-ray diffraction examinations provided evidence that KI nanocrystals doped in the nanotube spaces of SWCNHs at pressures below 0.1 MPa had the super-high-pressure B2 phase structure, which is induced at pressures above 1.9 GPa in bulk KI crystals. This finding of the supercompression function of the carbon nanotubular spaces can lead to the development of a new compression-free route to precious materials whose syntheses require the application of high pressure.     

Synthesis of acetic acid from methanol alone by homogeneous metal complex catalyst. Part 4. In-situ formation of catalyst species and halogen effect in the RuCl3·3H2O–SnX2 (X=F, Cl, Br, I) composite system

Highly selective formation of methyl acetate has been found possible from methanol alone using the catalyst generated in situ from RuCl₃·3H₂O and SnCl₂ as well as SnX₂ (X=F, Br, I). The reaction did not occur in the absence of SnCl₂ added and the optimum [Sn]/[Ru] ratio appeared at about 16. The halogen effect showed the order of SnF₂>SnCl₂>SnBr₂>SnI₂, which indicates the importance of cationic character of Ru(II) center to facilitate its electrophilic interaction with β-hydrogen of Ru–OCH₃ intermediate in the rate-limiting dehydrogenation step.     

Influence of the type of alkyl group on hydrolysis and polycondensation of tetraalkoxysilane

The early stage of hydrolysis and polycondensation of tetraalkoxysilanes (TAOS) in the closed TAOS-C₂H₅OH-H₂O-HCl system at 40°C was studied by the trimethylsilylation technique combined with the gas-liquid and gel permeation chromatographies. Tetramethoxy, tetraethoxy, tetra (n-propoxy) and tetra (n-butoxy) silanes were used as TAOS. The tendencies of variation with time in the distribution and molecular weight of silicate species in the solutions were almost the same in all the TAOS solutions, suggesting that the differences in the alkyl group of the TAOS had little effect on the hydrolysis and polycondensation.     

On some properties of almost-analytic tensors in an *O-space

Summary We consider an *O-space which is a kind of almost-Hermitian space. There is stated a theorem, that is, in a compact *O-space a skew-symmetric covariant almost-analytic tensor is closed. From this theorem, we get many important properties of almost-analytic tensors in an almost-K?hlerian space or a K-space and an interesting result related to the Lie derivative.     

A steep one-step [HS-HS] to [LS-LS] spin transition in a 4,4'-bipyridine linked one-dimensional coordination polymer constructed from a pyrazolato bridged Fe(II) dimer

The variable temperature magnetic susceptibility, X-ray crystallography, and M?ssbauer and Raman spectra of a new dinuclear complex-based one-dimensional coordination polymer [[Fe(II)2(NCS)2(mu-bpypz)2](micro-4,4'-bpy)].MeOH demonstrated a steep one-step [HS-HS] to [LS-LS] spin transition.     

Control of hole opening in single-wall carbon nanotubes and single-wall carbon nanohorns using oxygen

Due to the simplicity of the process, holes in the graphene walls of single-wall carbon nanotubes (SWNTs) and single-wall carbon nanohorns (SWNHs) have often been opened using O2 gas at high temperatures, even though this contaminates the nanotubes with carbonaceous dust (C-dust). To open holes with less C-dust contamination, we found that a slow temperature increase of 1 degrees C/min or less, in air, was effective. We also found that SWNHs having little C-dust could store a large quantity of materials inside the tubes. We infer that the local temperature increase due to the exothermic reaction of combustion may have been suppressed in the slow combustion process, which was effective in reducing the C-dust.     

Mathematical modeling of grown-in defects formation in Czochralski silicon

On the basis of a mathematical model proposed previously [S. Kobayashi, J. Crystal Growth 174 (1997) 163], oxygen precipitation in growing Czochralski (CZ) crystals is analyzed, and the calculated results are compared with experimental data of grown-in defects observed with laser scattering tomography (LST). The behavior of oxygen precipitates is qualitatively very similar to that of grown-in defects, but there are quantitative discrepancies between the calculation and the observation. The formation process of grown-in defects is discussed.     

Hydration of phosphate and borate glasses in an autoclave

Kinetics of hydration of CaO---Al₂O₃---P₂O₅ and Na₂O---CaO---B₂O₃---Al₂O₃ glasses in an autoclave at high temperatures and high pressures has been investigated. The hydration of the phosphate glasses may occur as a result of hydrolysis of glass constituents to form orthophosphate crystals. Cabal glasses which do not contain any alkali oxides have shown a quite high resistance to water. Substitution of sodium for calcium deteriorates the chemical durability of Cabal glasses.