This is a report regarding the preparation of nanosized gold/palladium bimetallic particles utilizing a cavitation phenomenon induced by irradiation of high-intensity ultrasound in an aqueous solution of gold(III) and palladium(II) ions. The particles are found to be composed of gold-core and palladium-shell by a transmission electron microscopic and nanoarea energy-dispersive X-ray spectroscopic analyses. Sodium dodecyl sulfate added to the sample solution is found to be a stabilizer for the nanoparticles generated as well as an important source of reducing species for noble metal ions. The thickness of a palladium shell and the size of a gold core seem to depend on the ratio of the concentrations of noble metal ions. The morphological differences in the sonochemical and radiochemical products suggest that the formation of a core-shell structure can be affected by the physical effects of ultrasound, such as effective stirring, microjet stream, or shock wave during the collapse of a cavitation bubble. Bimetallic nanoparticles show higher activities for the hydrogenation of 4-pentenoic acid than for those of the mixtures of monometallic nanoparticles with a corresponding gold/ palladium ratio. When the gold/palladium ratio is 1:4, the activity of the bimetallic particles is about three times higher than that of palladium monometallic nanoparticles prepared under the same conditions.

A series of poly(sodium acrylate) gels was synthesized via end-linking reaction between tetra-arm poly(tert-butyl acrylate)s by copper-catalyzed azide–alkyne cycloaddition followed by deprotection of tert-butyl group and neutralization. Characterization of the gels using gravimetry, IR measurement, and stretching test revealed that they have only small amounts of sol fractions, dangling chains, and trapped entanglements. The relationship between polymer weight fraction (ϕe) and shear modulus (G′) at equilibrium swelling in saline was expressed as G′ ∝ ϕe 2.5. The power index (2.5) was comparable with the theoretical value for nonionic gels swollen in good solvents (2.3). The relationship between G′ and ϕe was superior to that of poly(sodium acrylate) gels synthesized by conventional radical copolymerization. The difference may be partly attributed to the difference in the ratio of chemical cross-links to trapped entanglements.

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Porous alumina samples were prepared by the sol-gel process using aluminum tri-sec-butoxide in the presence of D-(＋)-glucose, D-(-)-ribose, or sucrose. The crystallinity and porosity of the alumina samples obtained were controlled by changing the amount of the sugar added and the calcination temperature. The less crystalline alumina samples exhibited a higher ability of sugar adsorption and a higher catalytic activity for the formose reaction. These observations indicate that lattice defects act as strong base sites.

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