The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments,zeta potential measurements and infrared spectrum analysis.Flotation test r...The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments,zeta potential measurements and infrared spectrum analysis.Flotation test results indicate that DLZ is the selective collector of chalcopyrite.Especially,the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems,while the recovery of pyrite is less than 10%.When using CaO as pH regulator,at pH=7-11,the floatability of pyrite is depressed and the recovery is less than 5%.Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ,confirming that collector DLZ shows selectivity to chalcopyrite and pyrite.And FTIR results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.展开更多
We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China ...We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.展开更多
Ore minerals in the sedimentary-type Cu deposits in the Xuanwei Formation overlying the Emeishan basalt are dominated by copper sulfides and native copper. As the ores mostly exhibit concretionary structure, previous ...Ore minerals in the sedimentary-type Cu deposits in the Xuanwei Formation overlying the Emeishan basalt are dominated by copper sulfides and native copper. As the ores mostly exhibit concretionary structure, previous researchers named them the ＂Madouzi-type Copper Deposit＂. Here the authors carried out mineralogical and isotopic studies on copper nodules in this ore deposit. The mineralogical study shows that copper nodules are composed of copper sulfides that have been cemented by ferruginous amorphous minerals, clay, and carbonaceous fragments in the modes of metasomatism and sedimentation. The nodules are preliminarily present as aggregates of gelatinous material. The isotopic analysis shows that the δ^13CPDB values of anhraxolite are within the range of-24.8‰-23.9‰, indicating that the anthraxolite is the product of sedimentary metamorphism of in-situ plants. The δ^34SV-CDT values of chalcocite are within the range of 7.6‰-13.1‰, close to those （about 11%~） of Permian seawater. The δ^34SV-CDT values of bornite and chalcopyrite are 21.6‰-22.2‰, similar to the sulfur isotopic composition （20‰） of marine sulfate, indicative of different sources of sulfur. The above characteristics indicate that the copper nodules were formed in such a process that Cu-bearing basalt underwent weathering-leaching and copper-bearing material was transported into waters （e.g., rivers, lakes, and swamps） and then adsorbed on clay and ferruginous amorphous mineral fragments. Then, the copper-bearing material was suspended and transported in the form of gelinite. In lake or swamp environment it was co-deposited with sediments to form copper nodules. At later stages there occurred metasomatism and hydrothermal superimposition, followed by the replacement of chalcocite by bornite and the superimposition of chalcopyrite over bornite, finally resulting in the formation of the ＂Madouzi-type＂ nodular copper deposit.展开更多
During infections,bacteria stimulate host cells to produce and release histamine,which is a key mediator of vital cellular processes in animals.However,the mechanisms underlying the bacterial cell’s ability to sense ...During infections,bacteria stimulate host cells to produce and release histamine,which is a key mediator of vital cellular processes in animals.However,the mechanisms underlying the bacterial cell’s ability to sense and respond to histamine are poorly understood.Herein,we show that HinK,a Lys R-type transcriptional regulator,is required to evoke responses to histamine in Pseudomonas aeruginosa,an important human pathogen.HinK directly binds to and activates the promoter of genes involved in histamine uptake and metabolism,iron acquisition,and Pseudomonas quinolone signal(PQS)biosynthesis.The transcriptional regulatory activity of HinK is induced when histamine is present,and it occurs when HinK binds with imidazole-4-acetic acid(Im AA),a histamine metabolite whose production in P.aeruginosa depends on the HinK-activated histamine uptake and utilization operon hin DAC-pa0222.Importantly,the inactivation of HinK inhibits diverse pathogenic phenotypes of P.aeruginosa.These results suggest that histamine acts as an interkingdom signal and provide insights into the mechanism used by pathogenic bacteria to exploit host regulatory signals to promote virulence.展开更多
The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate ...The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8＋δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8＋δ, which, we pro- pose, originates from the modulation-doping resultant twodimensional hole liquid confined in the CuO2 layers.展开更多
基金Project(50674102) supported by the National Natural Science Foundation of China
文摘The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments,zeta potential measurements and infrared spectrum analysis.Flotation test results indicate that DLZ is the selective collector of chalcopyrite.Especially,the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems,while the recovery of pyrite is less than 10%.When using CaO as pH regulator,at pH=7-11,the floatability of pyrite is depressed and the recovery is less than 5%.Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ,confirming that collector DLZ shows selectivity to chalcopyrite and pyrite.And FTIR results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.
基金Supported by the Major Science and Technology Program for Water Pollution Control and Treatment of China(Nos.2012ZX07103-005-01,2012ZX07103-004-02)the National Natural Science Foundation of China(Nos.41171366,41471075)the Science Foundation of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2012135013)
文摘We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population （M. aeruginosa） and their correlation with environmental factors in the water source area of Chaohu City, China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass, and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June, and the biomass of cyanobacteria reached a maximum in August. From February to March 2012, the main form of M. aeruginosa was the single-cell form; M. aeruginosa colonies began to appear from April, and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July, and then gradually decreased from August. The diameter range ofM. aeruginosa colonies was 18.37-237.77μm, and most of the colonies were distributed in the range 20-200μm, comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobaeterial growth was in the range of 15-30℃. In natural water bodies, photosynthetically active radiation had a significant positive influence on the colonial diameter of M. aeruginosa （P〈0.01）.
基金supported jointly by National Basic Research Program of China (Grant No. 2007CB411401)Special Fund of State Key Laboratory of Ore Deposit Geochemistry and National Natural Science Foundation of China (Grant No. 40773035)
文摘Ore minerals in the sedimentary-type Cu deposits in the Xuanwei Formation overlying the Emeishan basalt are dominated by copper sulfides and native copper. As the ores mostly exhibit concretionary structure, previous researchers named them the ＂Madouzi-type Copper Deposit＂. Here the authors carried out mineralogical and isotopic studies on copper nodules in this ore deposit. The mineralogical study shows that copper nodules are composed of copper sulfides that have been cemented by ferruginous amorphous minerals, clay, and carbonaceous fragments in the modes of metasomatism and sedimentation. The nodules are preliminarily present as aggregates of gelatinous material. The isotopic analysis shows that the δ^13CPDB values of anhraxolite are within the range of-24.8‰-23.9‰, indicating that the anthraxolite is the product of sedimentary metamorphism of in-situ plants. The δ^34SV-CDT values of chalcocite are within the range of 7.6‰-13.1‰, close to those （about 11%~） of Permian seawater. The δ^34SV-CDT values of bornite and chalcopyrite are 21.6‰-22.2‰, similar to the sulfur isotopic composition （20‰） of marine sulfate, indicative of different sources of sulfur. The above characteristics indicate that the copper nodules were formed in such a process that Cu-bearing basalt underwent weathering-leaching and copper-bearing material was transported into waters （e.g., rivers, lakes, and swamps） and then adsorbed on clay and ferruginous amorphous mineral fragments. Then, the copper-bearing material was suspended and transported in the form of gelinite. In lake or swamp environment it was co-deposited with sediments to form copper nodules. At later stages there occurred metasomatism and hydrothermal superimposition, followed by the replacement of chalcocite by bornite and the superimposition of chalcopyrite over bornite, finally resulting in the formation of the ＂Madouzi-type＂ nodular copper deposit.
基金supported by the Ministry of Science and Technology(MOST)of China(2016YFA0501503 and 2019ZX09721001-004-003)the National Natural Science Foundation of China(31670136,31870127,and 81861138047)+1 种基金the Science and Technology Commission of Shanghai Municipality(19JC1416400)the State Key Laboratory of Drug Research(SIMM2003ZZ-03)。
文摘During infections,bacteria stimulate host cells to produce and release histamine,which is a key mediator of vital cellular processes in animals.However,the mechanisms underlying the bacterial cell’s ability to sense and respond to histamine are poorly understood.Herein,we show that HinK,a Lys R-type transcriptional regulator,is required to evoke responses to histamine in Pseudomonas aeruginosa,an important human pathogen.HinK directly binds to and activates the promoter of genes involved in histamine uptake and metabolism,iron acquisition,and Pseudomonas quinolone signal(PQS)biosynthesis.The transcriptional regulatory activity of HinK is induced when histamine is present,and it occurs when HinK binds with imidazole-4-acetic acid(Im AA),a histamine metabolite whose production in P.aeruginosa depends on the HinK-activated histamine uptake and utilization operon hin DAC-pa0222.Importantly,the inactivation of HinK inhibits diverse pathogenic phenotypes of P.aeruginosa.These results suggest that histamine acts as an interkingdom signal and provide insights into the mechanism used by pathogenic bacteria to exploit host regulatory signals to promote virulence.
基金Acknowledgments The work was financially supported by the National Natural Science Foundation, Ministry of Science and Technology and Ministry of Education of China. The work at Brookhaven National Laboratory was supported by the Office of Basic Energy Sciences, US Department of Energy, under Contract No. DE- SC00112704.
文摘The pairing mechanism of high-temperature superconductivity in cuprates remains the biggest unresolved mystery in condensed matter physics. To solve the problem, one of the most effective approaches is to investigate directly the superconducting CuO2 layers. Here, by growing CuO2 monolayer films on Bi2Sr2CaCu2O8＋δ substrates, we identify two distinct and spatially separated energy gaps centered at the Fermi energy, a smaller U-like gap and a larger V-like gap on the films, and study their interactions with alien atoms by low-temperature scanning tunneling microscopy. The newly discovered U-like gap exhibits strong phase coherence and is immune to scattering by K, Cs and Ag atoms, suggesting its nature as a nodeless superconducting gap in the CuO2 layers, whereas the V-like gap agrees with the well-known pseudogap state in the underdoped regime. Our results support an s-wave superconductivity in Bi2Sr2CaCu2O8＋δ, which, we pro- pose, originates from the modulation-doping resultant twodimensional hole liquid confined in the CuO2 layers.
