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[1] The timing of the Jiufotang Formation remains speculative despite recent progress in the study of the Jehol Biota. In this paper we contribute to this topic with 40 Ar/ 39 Ar dating on K-feldspar (sanidine and orthoclase) from tuffs interbedded within the fossil-bearing shales of the Jiufotang Formation, from the upper part of the Jehol Group in Chaoyang, Liaoning, northeastern China. 40 Ar/ 39 Ar step heating analyses of K-feldspar and the SHRIMP U-Pb zircon data indicate that tuffs at the Shangheshou section erupted at 120.3 ± 0.7 million years ago. This result confirms an Aptian age for the Jiufotang Formation that was mainly based on biostratigraphic evidence. It also places stringent controls on the age of the fossils from the formation, providing a minimum age (120 Ma) for the four-winged dinosaur, Microraptor, and the seed-eating bird, Jeholornis.

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A kinetic study on soybean oil transesterification without a catalyst in subcritical and supercritical methanol was made at pressures between 8.7 and 36 MPa. It was found that the conversion of soybean oil into the corresponding methyl esters was enhanced considerably in the supercritical methanol. The apparent activation energies of the transesterification are different with the subcritical and the supercritical states of methanol, which are 11.2 and 56.0 kJ/mol (molar ratio of methanol to oil: 42, pressure: 28 MPa), respectively. The reaction pressure considerably influenced the yield of fatty acid methyl esters (FAME) in the pressure range from ambient pressure up to 25 MPa (280°C, 42:1). The reaction activation volume of transesterification in supercritical methanol is approximately -206 cm 3 /mol. The PDV " term accounts for nearly 10% of the apparent activation energy, and can not be ignored (280°C, 42:1).