The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerat...The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerated CO dissociation. The H2 was adsorbed first, and activated to form H＊ over metal sites, then reacted with carbonaceous species. The oxygen species for CO2 formation in the presence of hydrogen was mostly OH^＊, which reacted with adsorbed CO subsequently via CO^＊＋OH^＊ → CO2^＊＋H^＊; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C-O bond in the presence of H2 proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO on the surface via CO^＊＋2H^＊ → CH^＊＋OH^＊. The formation of the surface species （CH） from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.展开更多
In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that main...In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 （noe1）, higher H2O2 levels induced the generation of nitric oxide （NO） and higher S-nitrosothiol （SNO） levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species （RNS）. Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response （HR）, leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.展开更多
基金The National Key Project for Basic Research of China(973 Project)(No.2005CB221402)China National Petroleum Corporation
文摘The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerated CO dissociation. The H2 was adsorbed first, and activated to form H＊ over metal sites, then reacted with carbonaceous species. The oxygen species for CO2 formation in the presence of hydrogen was mostly OH^＊, which reacted with adsorbed CO subsequently via CO^＊＋OH^＊ → CO2^＊＋H^＊; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C-O bond in the presence of H2 proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO on the surface via CO^＊＋2H^＊ → CH^＊＋OH^＊. The formation of the surface species （CH） from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.
基金supported by grants from the National Natural Science Foundation of China (31171514, 30600407)the Ministry of Science and Technology of China (2009CB118506)+2 种基金an international exchange grant provided by the National Natural Science Foundation of Chinathe Royal Society of Edinburgh (30811130222)supported by a BBSRC grant BB/D0118091/1
文摘In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 （noe1）, higher H2O2 levels induced the generation of nitric oxide （NO） and higher S-nitrosothiol （SNO） levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species （RNS）. Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response （HR）, leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.
