GA 20-oxidase, the most important limiting enzyme, can catalyze a series of oxidization of GA biosynthesis pathway from GA12 to GA9 and from GA53 to GA20 in the higher plants. This paper reviews the studies on the cha...GA 20-oxidase, the most important limiting enzyme, can catalyze a series of oxidization of GA biosynthesis pathway from GA12 to GA9 and from GA53 to GA20 in the higher plants. This paper reviews the studies on the characters of GA 20-oxidase, the gene and the protein of GA 20-oxidase and the regulation of GA 20-oxidase gene expression in recent years. At the same time, the prospects for the gene transformation of GA 20-oxidase in agriculture, forestry and horticulture are also discussed.展开更多
Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified ...Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW.展开更多
用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的...用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的内界面、近 Si 表面的热分布进行分析;揭示出开管方式扩散 Ga 的实质是由 SiO_2薄膜对 Ga 原子的快速输运及其在 SiO_2-Si 内界面分凝效应两者统一的必然结果;并对该过程 Ga 杂质浓度分布机理进行了分析和讨论。展开更多
基金National Natural Science Foundation of China(Grant No.30271097)
文摘GA 20-oxidase, the most important limiting enzyme, can catalyze a series of oxidization of GA biosynthesis pathway from GA12 to GA9 and from GA53 to GA20 in the higher plants. This paper reviews the studies on the characters of GA 20-oxidase, the gene and the protein of GA 20-oxidase and the regulation of GA 20-oxidase gene expression in recent years. At the same time, the prospects for the gene transformation of GA 20-oxidase in agriculture, forestry and horticulture are also discussed.
文摘Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW.
文摘用 H2 和 Ga_2O_3的高温反应形成元素 Ga 的恒定表面源,通过 SiO_2-Si 复合结构实现了 Ga 在 Si 中的高均匀性掺杂;利用二次离子质谱分析(SIMS)、扩展电阻(SRP)、四探针测试等方法,对 P 型杂质 Ga 在 SiO_2薄膜、SiO_2-Si 两固相接触的内界面、近 Si 表面的热分布进行分析;揭示出开管方式扩散 Ga 的实质是由 SiO_2薄膜对 Ga 原子的快速输运及其在 SiO_2-Si 内界面分凝效应两者统一的必然结果;并对该过程 Ga 杂质浓度分布机理进行了分析和讨论。
