稻壳SiO2/钒催化剂上苯乙酮液相氧化（英文）

Rice husk silica catalyst loaded with 10 wt% vanadium was synthesized from agricultural biomass via a sol-gel synthetic route at pH = 9. The catalyst was characterized by different physico-chemical methods. The FTIR spectra showed the formation of Si–O–V and V=O stretching bands. The presence of vanadium was confirmed by EDX elemental analysis. RH-10V possessed a high specific surface area of 276 m2/g and pore volume of 0.83 ml/g. The prepared catalyst possessed a narrow pore size distribution centered around 7.9 nm. The catalytic performance of RH-10V was tested in the oxidation of acetophenone at 70 ℃. RH-10V was found to be an active catalyst in the oxidation of acetophenone, producing 36.28% conversion efficiency. The products identified were benzoic acid, 2-hydroxyacetophenone, phenol, acetic acid, and 3-hydroxyacetophenone.     

Facile Selective Diels-Alder Reactions of Chiral 5, 5-Dimethyl-4,6-Mathano-2-Methoxycarbonyl-2-Cyclohexenone. Application to the Total Synthesis of Qinghaosu

Starting from (--)-β-pinene,an efficient synthesis of qinghaosu (8) in natural form hasbeen accomplished. The synthesis involves keto ester 7 as a key intermediate which is conveniently pre-pared using the Diels-Alder chemistry developed in our laboratory.     

Error Bounds for the Truncation of Infinite Linear Differential Systems

An infinite system of linear differential equations of the form = Ax + f, x(0) = y is considered, wherex, y and f are infinite column vectors in E, and A is a constantinfinite matrix defining a bounded operator on E, where E isl₁, (c₀), or l. Explicit error bounds are obtained for the approximationof the solution of the infinite system by the solutions of thefinite truncated systems.     

A simple template-free sol–gel synthesis of spherical nanosilica from agricultural biomass

Mesoporous silica nanoparticles with a spherical morphology have been synthesized from rice husk (agricultural biomass) by a simple, template-free synthetic approach, which was carried out via sol–gel technique at ambient condition. Transmission electron micrographs revealed the formation of spherical silica nanoparticles with an average diameter of 50.9 nm. From the nitrogen adsorption–desorption analysis, the rice husk silica shows a high specific BET surface area of 245 m² g⁻¹. The silica nanoparticles have a narrow pore size distribution of 5.6–9.6 nm.     

RELATIVE WATER VAPOR PRESSURE OF WATER - IN - OIL MICROEMULSIONS BY HEADSPACE GAS CHROMATOGRAPHIC ANALYSIS

The headspace gas chromatography has been used for the determination of relative water vapor pressures of microemulsions consisting of Aerosol OT and various alkanes. The relative water vapor pressure of the micromulsions do not seem to vary significantly as a function of Chain function of chain length of n-alkane, i. e.from heptane to dodecane. This is in sharp contrast with its water solubilization capacity which increases markedly from the systems of heptane to nonane and it decreases sharply to that of dodecane. The results are explained in terms of the pseudophase model, and the effects of curvature and attraction on the microemulsion droplets.     

稻壳SiO_2/钒催化剂上苯乙酮液相氧化(英文)

Rice husk silica catalyst loaded with 10 wt% vanadium was synthesized from agricultural biomass via a sol-gel synthetic route at pH = 9. The catalyst was characterized by different physico-chemical methods. The FTIR spectra showed the formation of Si–O–V and V=O stretching bands. The presence of vanadium was confirmed by EDX elemental analysis. RH-10V possessed a high specific surface area of 276 m2/g and pore volume of 0.83 ml/g. The prepared catalyst possessed a narrow pore size distribution centered around 7.9 nm. The catalytic performance of RH-10V was tested in the oxidation of acetophenone at 70 ℃. RH-10V was found to be an active catalyst in the oxidation of acetophenone, producing 36.28% conversion efficiency. The products identified were benzoic acid, 2-hydroxyacetophenone, phenol, acetic acid, and 3-hydroxyacetophenone.