The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydropon...The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory.Plasmolemma permeability and contents of malonadialdehyde（MDA）,hydrogen peroxide（H2O2）,and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress.The dynamic tendency of catalase（CAT）activity was similar to that of the above four indices.The activity of peroxidase（POD）initially increased,then remained at a high level,and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation.However,POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage.With the addition of La （Ⅲ） of 20 mg·L-1,the rising tendency of plasmolemma permeability and contents of MDA,H2O2,and proline were slowed down during the stress period,whereas the declining speed was accelerated during the recovery period.The activities of CAT and POD were higher than those without La （Ⅲ） in all experiments.It suggested that the regulative effect of La （Ⅲ） on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species（ROS）,decrease contents of MDA and proline,and maintain normal plasmolemma permeability.Further more,the protective potential of La （Ⅲ） was better under low UV-B radiation than under a high one.展开更多
The structure and catalytic properties based on Chromium Oxide supported on mesoporous SBA-15 for oxidative dehydrogenation of propane by CO2 have been studied by using X-ray diffraction (XRD), ultraviolet-visible dif...The structure and catalytic properties based on Chromium Oxide supported on mesoporous SBA-15 for oxidative dehydrogenation of propane by CO2 have been studied by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and propane pulsing experiments in the absence of gas-phase O2. It has been shown that propane conversion and propene yield increase with Cr loadings. The propane conversion and propene yield on CrOx (Cr: 10wt%)/SBA-15 catalyst for oxidative dehydrogenation of propane by CO2 at 550 ℃ reach 24.8% and 21.8%, respectively .The results of ESR, UV-Vis DRS and propane pulsing experiments indicate that CrⅢ in the CrOx / SBA-15 catalyst is the main active species in oxidative dehydrogenation of propane by CO2 and CrⅥ, CrⅤ is inactive in dehydrogenation.展开更多
基金Project supported by the National Natural Science Foundation of China(30570323)the Foundation of State Developingand Reforming Committee(IFZ20051210)
文摘The effect of lanthanum （Ⅲ） on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation（UV-B：280~320 nm）at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory.Plasmolemma permeability and contents of malonadialdehyde（MDA）,hydrogen peroxide（H2O2）,and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress.The dynamic tendency of catalase（CAT）activity was similar to that of the above four indices.The activity of peroxidase（POD）initially increased,then remained at a high level,and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation.However,POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage.With the addition of La （Ⅲ） of 20 mg·L-1,the rising tendency of plasmolemma permeability and contents of MDA,H2O2,and proline were slowed down during the stress period,whereas the declining speed was accelerated during the recovery period.The activities of CAT and POD were higher than those without La （Ⅲ） in all experiments.It suggested that the regulative effect of La （Ⅲ） on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species（ROS）,decrease contents of MDA and proline,and maintain normal plasmolemma permeability.Further more,the protective potential of La （Ⅲ） was better under low UV-B radiation than under a high one.
文摘The structure and catalytic properties based on Chromium Oxide supported on mesoporous SBA-15 for oxidative dehydrogenation of propane by CO2 have been studied by using X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and propane pulsing experiments in the absence of gas-phase O2. It has been shown that propane conversion and propene yield increase with Cr loadings. The propane conversion and propene yield on CrOx (Cr: 10wt%)/SBA-15 catalyst for oxidative dehydrogenation of propane by CO2 at 550 ℃ reach 24.8% and 21.8%, respectively .The results of ESR, UV-Vis DRS and propane pulsing experiments indicate that CrⅢ in the CrOx / SBA-15 catalyst is the main active species in oxidative dehydrogenation of propane by CO2 and CrⅥ, CrⅤ is inactive in dehydrogenation.
