Activated carbon supported bimetallic CoMo carbides synthesized by carbothermal hydrogen reduction

A carbothermal hydrogen reduction method was employed for the preparation of activated carbon supported bimetallic carbide. The resultant samples were characterized by BET surface area measurement, X-ray diffraction, and temperature-programmed reduction-mass spectroscopy. The results showed that nanostructured beta-Mo2C can be formed on the activated carbon by carbothermal hydrogen reduction above 700 degreesC. The particle sizes of beta-Mo2C increase with increasing reaction temperatures and Mo loading. The bimetallic CoMo carbide can be synthesized by the carbothermal hydrogen reduction even around 600 degreesC. The bimetallic CoMo carbide is from carbothermal hydrogen reduction of CoMoO4 precursor and is easily formed when the Co/Mo molar ratio is 1.0. Separation of the bimetallic CoMo carbide phase into Mo carbide and Co metal occurs when the temperature of the reduction is above 700 degreesC. The addition of a second metal such as Co and Ni, decreases the formation temperature of carbide because the second metal promotes formation of CHx species from reactive carbon atoms or groups on carbon material and hydrogen, which further carburizes oxide precursors. (C) 2003 Elsevier Science Ltd. All rights reserved.

~(209)Fr的能级结构研究

利用能量为 90— 1 0 5MeV的16 O束流 ,通过197Au( 16 O ,4n)反应研究了2 0 9　Fr的高自旋态能级结构 .进行了γ射线的激发函数、γ γ延迟符合及γ射线的角分布测量 .首次建立了由 2 1条γ射线构成的2 0 9Fr的能级纲图 ,其中包括一个半寿命为 ( 52± 2 0 )ns的同质异能态 .基于2 0 9Fr与2 0 8Rn低位能级结构的相似性 ,用一个h9/ 2 价质子与2 0 8Rn激发态的弱耦合解释了2 0 9Fr的低位能级结构 .

高激发~(213)Fr核的形变研究

对 132MeV16O +197Au反应产生的裂变碎片和巨偶极共振γ射线进行了符合测量 ,得到了E =92MeV的高激发2 13 Fr的γ衰变谱和γ角关联谱 .观测到复合核巨偶极共振γ角关联谱存在很大的各向异性 .利用改进的统计模型程序分析了实验数据 ,不考虑裂变延迟时 ,统计模型计算可以很好拟合地实验结果 .通过对γ角关联谱的理论计算与实验结果的比较 ,可以得出高激发2 13 Fr核(E =92MeV)的形状从集体长椭球向非集体扁椭球变化

On a new genus and new species of xanthid crab (Crustacea, Decapoda, Brachyura, Xanthinae) from the South China Sea, with notes on the genus Liagore De Haan, 1833

A new genus and new species of xanthid crab, Ovatis simplex, is described from the South China Sea. The genus is closest to Liagore but can be distinguished by a suite of carapace and male gonopod characters. The systematic position of Liagore is also considered, and both genera, Liagore and Ovatis, are here referred to the subfamily Xanthinae. Comparisons with the allied genera, Paratergatis and Pulcratis, are also provided.