Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primar...Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primary cause for the resistance of Cyperus difformis.However,the effect of different mutations on AHAS function is not clear in Cyperus difformis.To confirm the effect of mutations on AHAS function,six biotypes were collected,including Pro197Arg,Pro197Ser,Pro197Leu,Asp376Glu,Trp574Leu and wild type,from Hunan,Anhui,Jiangxi and Jiangsu provinces,China and the function of AHAS was characterized.The AHAS in vitro inhibition assay results indicated that the mutations decreased the sensitivity of AHAS to pyrazosulfuron-ethyl,in which the I_(50)(the half maximal inhibitory concentration)of wild type AHAS was 0.04μmol L^(-1)and Asp376Glu,Pro197Leu,Pro197Arg,Pro197Ser and Trp574Leu mutations were 3.98,11.50,40.38,38.19 and 311.43μmol L^(-1),respectively.In the determination of enzyme kinetics parameters,the Km and the maximum reaction velocity(Vmax)of the wild type were 5.18 mmol L^(-1)and 0.12 nmol mg^(-1)min^(-1),respectively,and the Km values of AHAS with Asp376Glu,Trp574Leu,Pro197Leu and Pro197Ser mutations were 0.38-0.93 times of the wild type.The Km value of the Pro197Arg mutation was 1.14times of the wild type,and the Vmax values of the five mutations were 1.17-3.33-fold compared to the wild type.It was found that the mutations increased the affinity of AHAS to the substrate,except for the Pro197Arg mutation.At a concentration of 0.0032-100 mmol L^(-1)branched-chain amino acids(BCAAs),the sensitivity of the other four mutant AHAS biotypes to feedback inhibition decreased,except for the Pro197Arg mutation.This study elucidated the effect of different mutations on AHAS function in Cyperus difformis and provided ideas for further study of resistance development.展开更多
The Meteorological Archives of Inner Mongolia Autonomous Region is the largest professional meteorological archives in the Inner Mongolia region,and it is also the first national meteorological archives to be promoted...The Meteorological Archives of Inner Mongolia Autonomous Region is the largest professional meteorological archives in the Inner Mongolia region,and it is also the first national meteorological archives to be promoted to a national first-class archive management unit.Inner Mongolia Meteorological Archives now preserves more than 80,000 volumes of meteorological management files,meteorological observation records,meteorological scientific research files,and meteorological infrastructure files,providing the most fundamental support services for the development,research and application of meteorological services.展开更多
The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asym...The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asymmetric reduction ofα,β-unsaturated nitriles with water as a hydrogen source is reported.The reaction is catalyzed by the complex of[Ir(COD)Cl]_(2)and(R_(a),S)-Ph-Bn-SiPhox,and allows the preparation of useful enantioenriched chiral 3,3-disubstituted propionitriles with high optical purities in mild conditions.展开更多
The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scan...The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution electron microscopy （HRTEM）. The struc- tural feature was typical of the particle reinforced composites. The HRTEM images revealed that the observed Ag/SnO2 interface was absence of the precipitated phase and the lattice contrast across the interface was clear and sharp. The average particle size of SnO2 in composite was near 50 nm and it was well dispersed in spherical shape. The thermodynamic mechanism of reactive synthesis method was also discussed. The electronic density distribution analysis of the interface showed the charges of Ag atoms transmitted to 0 atoms and the conductivity of the material was also affected. No extra compounds expected such as AgxOy formed at interface. The distribution of electrons was of inequality near the interface which explained why the mechanical property of the metal/ceramic materials was improved but the machining property declined.展开更多
The mechanical properties of nano-scale Cu/FeS composite were simulated by molecular dynamics （MD） simulation in this paper. Through the analysis on the stress-strain curves, the results of MD simulation were in goo...The mechanical properties of nano-scale Cu/FeS composite were simulated by molecular dynamics （MD） simulation in this paper. Through the analysis on the stress-strain curves, the results of MD simulation were in good agreement with mechanisms of macroscopic deformation. When the size of particles was smaller than a certain value, the relationship between yield strength and size, which was different from the large size crystals abided by the contrary Hall-Petch relationship. Based on the discussion of nano-scale Cu/FeS composite, some interesting conclusions were obtained. For example, the ＂S＂ type curves were discovered in stress-strain curves and the anisotropy of FeS was very evident when the exposures of reinforcing phase （FeS） were different and so on. The basic theories and calculations of the composite that contains nano-scale particles were discussed. At the same time, a new modeling building method of composites, which was close to actual experiences, were considered in this paper.展开更多
New blue-light promoted methods for the addition of iodoacetonitrile(ICH_(2)CN)to alkene/alkynes have been developed.The reaction led to the formation of cyanoalkylated products when conjugated alkene/styrene was used...New blue-light promoted methods for the addition of iodoacetonitrile(ICH_(2)CN)to alkene/alkynes have been developed.The reaction led to the formation of cyanoalkylated products when conjugated alkene/styrene was used.In the case of alkynes and non-conjugated alkenes,iodoalkylation takes place furnishing the corresponding alkenyl iodides and alkyl iodides,respectively.Notably,trans-alkenyl iodides were obtained as the major product.A plausible reaction mechanism is also proposed.展开更多
基金funded by the National Natural Science Foundation of China(31972281)。
文摘Cyperus difformis L.is a troublesome weed in paddy fields and has attracted attention due to its resistance to acetohydroxyacid synthase(AHAS)inhibitors.It was found that the amino acid mutation in AHAS was the primary cause for the resistance of Cyperus difformis.However,the effect of different mutations on AHAS function is not clear in Cyperus difformis.To confirm the effect of mutations on AHAS function,six biotypes were collected,including Pro197Arg,Pro197Ser,Pro197Leu,Asp376Glu,Trp574Leu and wild type,from Hunan,Anhui,Jiangxi and Jiangsu provinces,China and the function of AHAS was characterized.The AHAS in vitro inhibition assay results indicated that the mutations decreased the sensitivity of AHAS to pyrazosulfuron-ethyl,in which the I_(50)(the half maximal inhibitory concentration)of wild type AHAS was 0.04μmol L^(-1)and Asp376Glu,Pro197Leu,Pro197Arg,Pro197Ser and Trp574Leu mutations were 3.98,11.50,40.38,38.19 and 311.43μmol L^(-1),respectively.In the determination of enzyme kinetics parameters,the Km and the maximum reaction velocity(Vmax)of the wild type were 5.18 mmol L^(-1)and 0.12 nmol mg^(-1)min^(-1),respectively,and the Km values of AHAS with Asp376Glu,Trp574Leu,Pro197Leu and Pro197Ser mutations were 0.38-0.93 times of the wild type.The Km value of the Pro197Arg mutation was 1.14times of the wild type,and the Vmax values of the five mutations were 1.17-3.33-fold compared to the wild type.It was found that the mutations increased the affinity of AHAS to the substrate,except for the Pro197Arg mutation.At a concentration of 0.0032-100 mmol L^(-1)branched-chain amino acids(BCAAs),the sensitivity of the other four mutant AHAS biotypes to feedback inhibition decreased,except for the Pro197Arg mutation.This study elucidated the effect of different mutations on AHAS function in Cyperus difformis and provided ideas for further study of resistance development.
文摘The Meteorological Archives of Inner Mongolia Autonomous Region is the largest professional meteorological archives in the Inner Mongolia region,and it is also the first national meteorological archives to be promoted to a national first-class archive management unit.Inner Mongolia Meteorological Archives now preserves more than 80,000 volumes of meteorological management files,meteorological observation records,meteorological scientific research files,and meteorological infrastructure files,providing the most fundamental support services for the development,research and application of meteorological services.
基金grateful to the National Natural Science Foundation of China(Nos.21961045 and 22061048)the Basic Research Project of Chongqing Academy of Chinese Materia Medica(No.jbky20190028)+2 种基金the Fund Project of Yunnan Key Laboratory of Pharmacology for Natural Products(No.YKLPNP-K2303)Yunnan Provincial Key Laboratory Construction Plan Funding of UniversitiesYunnan Provincial Engineering Research Center Construction Plan Funding of Universities for their financial support.
文摘The nitrile compounds are present in a variety of biologically active natural products and pharmaceuticals,and the nitrile groups are versatile synthetic intermediates to other functionalized compounds.Herein,the asymmetric reduction ofα,β-unsaturated nitriles with water as a hydrogen source is reported.The reaction is catalyzed by the complex of[Ir(COD)Cl]_(2)and(R_(a),S)-Ph-Bn-SiPhox,and allows the preparation of useful enantioenriched chiral 3,3-disubstituted propionitriles with high optical purities in mild conditions.
基金supported by the National Natural Science Foundation of China (Nos. 2008CB617609,u0837601, u0837603 and 50874054)the Science Innovation Foundation of Kunming University of Science and Technology
文摘The electric contact material of Ag/SnO2 composite was achieved by reactive synthesis method. The compositions and microstructure of Ag/SnO2 composite were analyzed and characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution electron microscopy （HRTEM）. The struc- tural feature was typical of the particle reinforced composites. The HRTEM images revealed that the observed Ag/SnO2 interface was absence of the precipitated phase and the lattice contrast across the interface was clear and sharp. The average particle size of SnO2 in composite was near 50 nm and it was well dispersed in spherical shape. The thermodynamic mechanism of reactive synthesis method was also discussed. The electronic density distribution analysis of the interface showed the charges of Ag atoms transmitted to 0 atoms and the conductivity of the material was also affected. No extra compounds expected such as AgxOy formed at interface. The distribution of electrons was of inequality near the interface which explained why the mechanical property of the metal/ceramic materials was improved but the machining property declined.
基金supported by the National Basic Research Program of China (973 Program) under Grant No. 2008CB617609the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China under Grant No.2007BAE23B02
文摘The mechanical properties of nano-scale Cu/FeS composite were simulated by molecular dynamics （MD） simulation in this paper. Through the analysis on the stress-strain curves, the results of MD simulation were in good agreement with mechanisms of macroscopic deformation. When the size of particles was smaller than a certain value, the relationship between yield strength and size, which was different from the large size crystals abided by the contrary Hall-Petch relationship. Based on the discussion of nano-scale Cu/FeS composite, some interesting conclusions were obtained. For example, the ＂S＂ type curves were discovered in stress-strain curves and the anisotropy of FeS was very evident when the exposures of reinforcing phase （FeS） were different and so on. The basic theories and calculations of the composite that contains nano-scale particles were discussed. At the same time, a new modeling building method of composites, which was close to actual experiences, were considered in this paper.
基金We are grateful to the National Natural Science Foundation of China(Nos.21961045,22061048)the Yunnan Provincial Key Laboratory Construction Plan Funding of Universities and Yunnan Provincial Engineering Research Center Construction Plan Funding of Universities for their financial support.
文摘New blue-light promoted methods for the addition of iodoacetonitrile(ICH_(2)CN)to alkene/alkynes have been developed.The reaction led to the formation of cyanoalkylated products when conjugated alkene/styrene was used.In the case of alkynes and non-conjugated alkenes,iodoalkylation takes place furnishing the corresponding alkenyl iodides and alkyl iodides,respectively.Notably,trans-alkenyl iodides were obtained as the major product.A plausible reaction mechanism is also proposed.
