Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content an...Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content and chloroplast structure little changed in the course of desiccation, therefore has been called homoiochlorophyllous desiccation-tolerant plants (HDTs). Another type of resurrection angiosperms that lost its chlorophyll dining desiccation is called poikilochlorophyllous desiccation-tolerant plants (PDTs). HDTs have been received more attention because of simplicity of protection mechanism which is much easy to the study and utilization of the desiccation tolerance of resurrection angiosperms. Recent advances in studies of photosynthesis of resurrection angiosperms indicate that photochemical activities are sensitive indicators for the study of physiological state of resurrection angiosperms during desiccation and rehydration. Photochemical activities of resurrection angiosperms are inhibited with loss of water similar to those of general plants, however, the magic thing is that they could reactivate rapidly during rehydration even losing more than 95% water. Up-regulations in xanthophyll cycle and antioxidative systems as well as preservation in integrity and stability of photosynthetic membranes during desiccation may be very important to desiccation tolerance of resurrection angiosperms. The fact that phosphate treatment in rehydration stage also strongly influences resurrection indicated importance of studies on rehydration stages of resurrection angiosperms.展开更多
By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were inv...By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were investigated. The physicochemical properties and redox potential of the catalyst were characterized by N2 adsorption-desorption, XRD, H2-TPR, and XPS. In order to understand the relationship between the oxidation stability of CO and the presence of water, the CO oxidation mechanism was studied by in situ DRIFT. Support pretreatment markedly promoted catalyst stability during CO oxidation; CO conversion was 78% after 150 h at saturated humidity and freezing point. Modification led to an obvious decrease in chloride ion concentration and enhancement in hydrophobicity. The role of water in CO oxidation was complicated. The presence of water favored CO oxidation over active Pd~+ species and Pd0 reoxidation by Cu^(2+) species. Meanwhile, water also inhibited the formation of the active Pd~+ species and helped to produce carbonate species. Compared with the form of the carbonate species, the inhibition of water to produce active Pd~+ species played the main detrimental role in catalyst stability.展开更多
Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an ad...Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.展开更多
The flower-like microsphere Bi2WO6 with an average diameter of 2.5 μm is synthesized by a simple hydrothermal method in the presence of surfactant sodium dodecyl sulfate (SDS) or polyvinylpyrrolidone (PVP). The c...The flower-like microsphere Bi2WO6 with an average diameter of 2.5 μm is synthesized by a simple hydrothermal method in the presence of surfactant sodium dodecyl sulfate (SDS) or polyvinylpyrrolidone (PVP). The crystalline phase, compositions, morphology, microstructure, surface area and band gap energy of the Bi2WO6 are characterized by X-ray diffraction, X-ray energy-dispersive spectrum, scanning electron microscopy, transmission electron microscopy and absorption spectra. It is found that surfactant has a significant influence on the microstructure and properties of the samples. The surfaetant SDS en- hances the surface area and photocatalytic activity of Bi2WO6, while the surfactant PVP has an opposite effect. Under Xe lamp irradiation, the Bi2WO6 sample prepared in the presence of SDS can degrade dye Rhodamine B (RhB) effectively.展开更多
文摘Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content and chloroplast structure little changed in the course of desiccation, therefore has been called homoiochlorophyllous desiccation-tolerant plants (HDTs). Another type of resurrection angiosperms that lost its chlorophyll dining desiccation is called poikilochlorophyllous desiccation-tolerant plants (PDTs). HDTs have been received more attention because of simplicity of protection mechanism which is much easy to the study and utilization of the desiccation tolerance of resurrection angiosperms. Recent advances in studies of photosynthesis of resurrection angiosperms indicate that photochemical activities are sensitive indicators for the study of physiological state of resurrection angiosperms during desiccation and rehydration. Photochemical activities of resurrection angiosperms are inhibited with loss of water similar to those of general plants, however, the magic thing is that they could reactivate rapidly during rehydration even losing more than 95% water. Up-regulations in xanthophyll cycle and antioxidative systems as well as preservation in integrity and stability of photosynthetic membranes during desiccation may be very important to desiccation tolerance of resurrection angiosperms. The fact that phosphate treatment in rehydration stage also strongly influences resurrection indicated importance of studies on rehydration stages of resurrection angiosperms.
基金supported by the National Key Research and Development Program of China(2016YFC0204300)National Natural Science Foundation of China(21207037,21333003,21571061)+1 种基金the "Shu Guang" Project of the Shanghai Municipal Education Commission(12SG29)the Commission of Science and Technology of Shanghai Municipality(15DZ1205305)~~
文摘By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were investigated. The physicochemical properties and redox potential of the catalyst were characterized by N2 adsorption-desorption, XRD, H2-TPR, and XPS. In order to understand the relationship between the oxidation stability of CO and the presence of water, the CO oxidation mechanism was studied by in situ DRIFT. Support pretreatment markedly promoted catalyst stability during CO oxidation; CO conversion was 78% after 150 h at saturated humidity and freezing point. Modification led to an obvious decrease in chloride ion concentration and enhancement in hydrophobicity. The role of water in CO oxidation was complicated. The presence of water favored CO oxidation over active Pd~+ species and Pd0 reoxidation by Cu^(2+) species. Meanwhile, water also inhibited the formation of the active Pd~+ species and helped to produce carbonate species. Compared with the form of the carbonate species, the inhibition of water to produce active Pd~+ species played the main detrimental role in catalyst stability.
基金supported by the National Natural Science Foundation of China(91126006,11305102)the Research Fund for the Doctoral Program of Higher Education of China(20130073110046)
文摘Separation of trivalent minor actinides(MA(ⅡI): Am(ⅡI), Cm(ⅡI)) from fission products(FP) in high-level liquid waste(HLLW) is an important task in advanced nuclear-fuel reprocessing systems. For this purpose, an advanced aqueous partitioning process based on extraction chromatography method was studied. Because R-BTP extractants(R-BTP: 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine, R = alkyl group) exhibit high selectivity for MA(ⅡI) over trivalent rare-earth elements(RE(ⅡI)), a novel adsorbent isoHex-BTP/SiO2-P was prepared by impregnating isoHex-BTP extractant into the macroporous SiO2-P support with a mean diameter of 60 μm. The stability of isoHex-BTP/SiO2-P against nitric acid and γ-irradiation was investigated. It was found that isoHex-BTP/SiO2-P adsorbent shows good adsorption affinity to Dy(ⅡI). The hydrolytic and radiolytic stability of isoHex-BTP/SiO2-P adsorbent in 0.01 mol/L HNO3 was fairly promising. However, the adsorption amount Q of Dy(ⅡI) decreased dramatically in 3 mol/L HNO3 with the increase of the absorbed dose and became nearly zero at the absorbed dose over 46 kGy. These results suggest that with the synergetic effect of radiation and acidic hydrolysis, the adsorbent instantly loses its efficacy.
基金supported by the National High Technology Research and Development Program of China (2009AA03Z217)the National Natural Science Foundation of China (90922028, 50842027)
文摘The flower-like microsphere Bi2WO6 with an average diameter of 2.5 μm is synthesized by a simple hydrothermal method in the presence of surfactant sodium dodecyl sulfate (SDS) or polyvinylpyrrolidone (PVP). The crystalline phase, compositions, morphology, microstructure, surface area and band gap energy of the Bi2WO6 are characterized by X-ray diffraction, X-ray energy-dispersive spectrum, scanning electron microscopy, transmission electron microscopy and absorption spectra. It is found that surfactant has a significant influence on the microstructure and properties of the samples. The surfaetant SDS en- hances the surface area and photocatalytic activity of Bi2WO6, while the surfactant PVP has an opposite effect. Under Xe lamp irradiation, the Bi2WO6 sample prepared in the presence of SDS can degrade dye Rhodamine B (RhB) effectively.