The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extractio...The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extraction of uranium from seawater via converging the cooperative functions of adsorption-photocatalysis into the nanospace of covalent organic frameworks(COFs).Functionalization of the organic linkers in the multicomponent COFs allowed exploration of the relationship between material composition and adsorption-photocatalytic activity for uranium extraction.The presence of amidoxime groups in the COFs offered selective binding sites for uranyl,whilst triazine units and bipyridine-Pd groups acted cooperatively to photocatalytically reduce adsorbed U(Ⅵ)to a U(Ⅳ)solid product(UO2)for facile collection.One of our developed COFs,4-Pd-AO,displayed exceptional performance in sequestering and reducing uranyl from natural seawater,with a high extraction capacity of 4.62 mg U/g per day(average data)under visible light irradiation.Mechanistic studies revealed that 4-Pd-AO not only reduced adsorbed uranyl(Ⅵ)to U(Ⅳ)O_(2),but also generated ^(1)O_(2) and superoxide radicals under visible light excitation,thus affording excellent antibacterial and antialgal activities(i.e.,antibiofouling properties)for sustained efficient uranium extraction performance.This proof-ofconcept study establishes multicomponent COFs as promising candidates for efficient uranium extraction from seawater.展开更多
Alkaline phosphatase activity (APA) and dissolved phosphorus were monitored during the batch cultures of two bone microalgae. Results indicate that variation of APA was in the shape of 'S' curve. Different spe...Alkaline phosphatase activity (APA) and dissolved phosphorus were monitored during the batch cultures of two bone microalgae. Results indicate that variation of APA was in the shape of 'S' curve. Different specs of dissolved phaphorus had different effects on APA. The concentrations of dis solved inorganic phosphorus (DIP) and and molecular dissolved organic phosphorus (SDOP) had a sig nificant effect on APA, while the concentration of large molecular dissolved organic phosphorus (LDOP) had a little effect on APA., and the increase of APA could accelerate the decomposing of LDOP in the medium. Results also show that algae species and abundance had why a little effect on APA.展开更多
[Objective] To clarify the effects of different straw retention regimes on soil fertility in double cropping paddy field. [Method] The effects of different straw reten- tion regimes on total organic carbon （CToc）, a...[Objective] To clarify the effects of different straw retention regimes on soil fertility in double cropping paddy field. [Method] The effects of different straw reten- tion regimes on total organic carbon （CToc）, active carbon （CA） and mineralized carbon （CM） were analyzed, and carbon pool active （A）, carbon pool active index （A/）, carbon pool index （CPI） and carbon pool management index （CPMi） for each treat- ment were calculated. [Result] Compared with the unfertilized treatment （CK）, CToc, CA, CM and the available ratio of soil carbon were increased in the treatment of re- turning early season and late season rice straws to field. With the same nutrient application, CToc, CA and the available ratio of soil carbon in the field with straw re- turned to field were higher than that of straw incineration and no straw returning, and the change in soil CA content was more significant. The difference in CPMI be- tween different treatments reached significant or very significant level, and the value was in the order of straw directly returned to field 〉 straw returned to field after in- cineration 〉 no straw returned to field. [Conclusion] This study provided theoretical bases for the increase of soil CA content and soil fertility in double rice fields.展开更多
基金funding support from the National Science Foundation of China(grant nos.U2167218 and 22006036)National Key Research and Development Program of China(grant nos.2017YFA0207002 and 2018YFC1900105)+4 种基金the Science Challenge Project(grant no.TZ2016004)the Beijing Outstanding Young Scientist Programthe Students Innovation Training Program(grant no.202106014)the Robert A.Welch Foundation(B-0027)(S.M.)support from the 14W station in Shanghai Synchrotron Radiation Facility(SSRF).
文摘The extraction of uranium from seawater is challenging though it offers tremendous potential for the sustainable production of nuclear fuel for the energy sector.Herein,we report a new strategy for efficient extraction of uranium from seawater via converging the cooperative functions of adsorption-photocatalysis into the nanospace of covalent organic frameworks(COFs).Functionalization of the organic linkers in the multicomponent COFs allowed exploration of the relationship between material composition and adsorption-photocatalytic activity for uranium extraction.The presence of amidoxime groups in the COFs offered selective binding sites for uranyl,whilst triazine units and bipyridine-Pd groups acted cooperatively to photocatalytically reduce adsorbed U(Ⅵ)to a U(Ⅳ)solid product(UO2)for facile collection.One of our developed COFs,4-Pd-AO,displayed exceptional performance in sequestering and reducing uranyl from natural seawater,with a high extraction capacity of 4.62 mg U/g per day(average data)under visible light irradiation.Mechanistic studies revealed that 4-Pd-AO not only reduced adsorbed uranyl(Ⅵ)to U(Ⅳ)O_(2),but also generated ^(1)O_(2) and superoxide radicals under visible light excitation,thus affording excellent antibacterial and antialgal activities(i.e.,antibiofouling properties)for sustained efficient uranium extraction performance.This proof-ofconcept study establishes multicomponent COFs as promising candidates for efficient uranium extraction from seawater.
基金National Natural Science Foundation of China ! 49206063.
文摘Alkaline phosphatase activity (APA) and dissolved phosphorus were monitored during the batch cultures of two bone microalgae. Results indicate that variation of APA was in the shape of 'S' curve. Different specs of dissolved phaphorus had different effects on APA. The concentrations of dis solved inorganic phosphorus (DIP) and and molecular dissolved organic phosphorus (SDOP) had a sig nificant effect on APA, while the concentration of large molecular dissolved organic phosphorus (LDOP) had a little effect on APA., and the increase of APA could accelerate the decomposing of LDOP in the medium. Results also show that algae species and abundance had why a little effect on APA.
基金Supported by the National Key Technology R&D Program during the Eleventh Five-year Plan Period,China(2006BAD02A04)the Key Technology R&D Program of Jiangxi Province,China(2009BNA03800)~~
文摘[Objective] To clarify the effects of different straw retention regimes on soil fertility in double cropping paddy field. [Method] The effects of different straw reten- tion regimes on total organic carbon （CToc）, active carbon （CA） and mineralized carbon （CM） were analyzed, and carbon pool active （A）, carbon pool active index （A/）, carbon pool index （CPI） and carbon pool management index （CPMi） for each treat- ment were calculated. [Result] Compared with the unfertilized treatment （CK）, CToc, CA, CM and the available ratio of soil carbon were increased in the treatment of re- turning early season and late season rice straws to field. With the same nutrient application, CToc, CA and the available ratio of soil carbon in the field with straw re- turned to field were higher than that of straw incineration and no straw returning, and the change in soil CA content was more significant. The difference in CPMI be- tween different treatments reached significant or very significant level, and the value was in the order of straw directly returned to field 〉 straw returned to field after in- cineration 〉 no straw returned to field. [Conclusion] This study provided theoretical bases for the increase of soil CA content and soil fertility in double rice fields.
