[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the ...[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the Actinomycetes genomic DNA was successful extracted. 16S rDNA was amplified by PCR and sequenced by Sanger dideoxy sequencing method. [Result] All the sequences were blasted in genbank,eight strains belonged to the genus of Streptomyces (80%),and two strains belonged to the genus of Nocardiopsis (20%). [Conclusion] There are many different Actinomycetes species in Mangrove forest soil samples in Beihai,Guangxi Province.展开更多
A new scheme for the preparation of highly dispersed precious metal catalysts is proposed in this work. Samples of LaCol-xPtxO3/SiO2 （x = 0.03, 0.05, 0.07, 0.09, and 0.10） were prepared through a simple method of ci...A new scheme for the preparation of highly dispersed precious metal catalysts is proposed in this work. Samples of LaCol-xPtxO3/SiO2 （x = 0.03, 0.05, 0.07, 0.09, and 0.10） were prepared through a simple method of citrate acid complexa-tion combined with impregnation. In a nanocrystallite of LaCOl-xPtxO3, ions of lanthanum, cobalt, and platinum are evenly mixed at the atomic level and confined within the nanocrystallite. In the reduction process, platinum ions were reduced and migrated onto the surface of the nanocrystallite, and the platinum should be highly dispersed owing to the even mixing of the platinum ions in the precursor. When x = 0.05 or lower, the highest dispersion of Pt could be achieved. The highly dispersed Pt is stable, because of the strong interaction between Pt atoms and the support. The catalysts were characterized by BET surface area, temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, CO temperature-programmed desorption, and turnover frequency. Compared with general precious metal Pt catalysts, the LaCo0.95Pt0.05O3/ SiO2 catalyst exhibited better activity for CO oxidation, and it maintained stability at a high temperature of 400 ℃ for 250 h with complete CO conversion.展开更多
Aims Successful plant invaders usually exhibit three strategies:Jack-of-all-trades(more robust in stressful sites),Master-of-some(more responsive in favorable sites)and Jack-and-master(both robustness and responsivene...Aims Successful plant invaders usually exhibit three strategies:Jack-of-all-trades(more robust in stressful sites),Master-of-some(more responsive in favorable sites)and Jack-and-master(both robustness and responsiveness).To revisit these strategies,we examined how soil inorganic nitrogen(N)compositions and levels influence the success of native and invasive plant congeners in the context of plant communities.Methods We conducted an experiment involving three fixed factors:species origin,N composition and N level.Here,we selected 21 plant species(eight pairs of invasive and native congeners and five non-congeneric natives)to assemble plant communities,which were subject to nine N environments consisting of three N compositions(3:1,2:2 and 1:3 NO3−/NH4+)and three N levels(low,medium and high N).We determined the following metrics:total biomass,relative biomass(a proxy of species success),mortality rate and mortality time.Important Findings Across nine N environments,native and invasive congeners exhibited similar total biomass,relative biomass and mortality time,but invaders had a marginally lower mortality rate than natives.Similar success between native and invasive congeners was linked to their similar growth and tolerance.N compositions influenced mortality time and N levels affected the total biomass and relative biomass.Importantly,species origin,N composition and N level interactively affected the total biomass,relative biomass and mortality time.These findings suggest that native and invasive plant congeners may be similarly successful across different N environments,and that inorganic N compositions and levels both contribute to plant invasion success.展开更多
基金Supported by Science Foundation of Guangxi Province (0899006)South China Agricultural University Principal Foundation ( 5100-k05099)~~
文摘[Objective] The aim was to identify the species diversity of Actinomycetes from Mangrove forest in Beihai,Guangxi Province. [Method] 10 strains of typical Actinomycetes were isolated from Mangrove forest soil,and the Actinomycetes genomic DNA was successful extracted. 16S rDNA was amplified by PCR and sequenced by Sanger dideoxy sequencing method. [Result] All the sequences were blasted in genbank,eight strains belonged to the genus of Streptomyces (80%),and two strains belonged to the genus of Nocardiopsis (20%). [Conclusion] There are many different Actinomycetes species in Mangrove forest soil samples in Beihai,Guangxi Province.
基金supported by the National Natural Science Foundation of China(Nos.21576192,21776214)
文摘A new scheme for the preparation of highly dispersed precious metal catalysts is proposed in this work. Samples of LaCol-xPtxO3/SiO2 （x = 0.03, 0.05, 0.07, 0.09, and 0.10） were prepared through a simple method of citrate acid complexa-tion combined with impregnation. In a nanocrystallite of LaCOl-xPtxO3, ions of lanthanum, cobalt, and platinum are evenly mixed at the atomic level and confined within the nanocrystallite. In the reduction process, platinum ions were reduced and migrated onto the surface of the nanocrystallite, and the platinum should be highly dispersed owing to the even mixing of the platinum ions in the precursor. When x = 0.05 or lower, the highest dispersion of Pt could be achieved. The highly dispersed Pt is stable, because of the strong interaction between Pt atoms and the support. The catalysts were characterized by BET surface area, temperature-programmed reduction, X-ray diffraction, transmission electron microscopy, CO temperature-programmed desorption, and turnover frequency. Compared with general precious metal Pt catalysts, the LaCo0.95Pt0.05O3/ SiO2 catalyst exhibited better activity for CO oxidation, and it maintained stability at a high temperature of 400 ℃ for 250 h with complete CO conversion.
基金by Ministry of Science and Technology of the People's Republic of China(2017YFC1200102)the National Natural Science Foundation of China(31971552).
文摘Aims Successful plant invaders usually exhibit three strategies:Jack-of-all-trades(more robust in stressful sites),Master-of-some(more responsive in favorable sites)and Jack-and-master(both robustness and responsiveness).To revisit these strategies,we examined how soil inorganic nitrogen(N)compositions and levels influence the success of native and invasive plant congeners in the context of plant communities.Methods We conducted an experiment involving three fixed factors:species origin,N composition and N level.Here,we selected 21 plant species(eight pairs of invasive and native congeners and five non-congeneric natives)to assemble plant communities,which were subject to nine N environments consisting of three N compositions(3:1,2:2 and 1:3 NO3−/NH4+)and three N levels(low,medium and high N).We determined the following metrics:total biomass,relative biomass(a proxy of species success),mortality rate and mortality time.Important Findings Across nine N environments,native and invasive congeners exhibited similar total biomass,relative biomass and mortality time,but invaders had a marginally lower mortality rate than natives.Similar success between native and invasive congeners was linked to their similar growth and tolerance.N compositions influenced mortality time and N levels affected the total biomass and relative biomass.Importantly,species origin,N composition and N level interactively affected the total biomass,relative biomass and mortality time.These findings suggest that native and invasive plant congeners may be similarly successful across different N environments,and that inorganic N compositions and levels both contribute to plant invasion success.
