Recently,the newly synthesized septuple-atomic layer two-dimensional(2D)material MoSi_(2)N_(4)(MSN)has attracted attention worldwide.Our work delves into the effect of vacancies and external electric fields on the ele...Recently,the newly synthesized septuple-atomic layer two-dimensional(2D)material MoSi_(2)N_(4)(MSN)has attracted attention worldwide.Our work delves into the effect of vacancies and external electric fields on the electronic properties of the MSN/graphene(Gr)heterostructure using first-principles calculation.We find that four types of defective structures,N-in,N-out,Si and Mo vacancy defects of monolayer MSN and MSN/Gr heterostructure are stable in air.Moreover,vacancy defects can effectively modulate the charge transfer at the interface of the MSN/Gr heterostructure as well as the work function of the pristine monolayer MSN and MSN/Gr heterostructure.Finally,the application of an external electric field enables the dynamic switching between n-type and p-type Schottky contacts.Our work may offer the possibility of exceeding the capabilities of conventional Schottky diodes based on MSN/Gr heterostructures.展开更多
Nicotine,a toxic and addictive alkaloid from tobacco,is an environmental pollutant.However,nicotine-degrading bacteria(NDB)and their function in tobacco planting soil are not fully understood.First,52 NDB strains belo...Nicotine,a toxic and addictive alkaloid from tobacco,is an environmental pollutant.However,nicotine-degrading bacteria(NDB)and their function in tobacco planting soil are not fully understood.First,52 NDB strains belonging to seven genera were isolated from tobacco soil.The most dominant genera were Flavobacterium(36.5%),Pseudomonas(30.8%),and Arthrobacter(15.4%),and Chitinophaga and Flavobacterium have not been previously reported.Then,two efficient NDB strains,Arthrobacter nitrophenolicus ND6 and Stenotrophomonas geniculata ND16,were screened and inoculated in the compost fertilizer from tobacco waste.The nicotine concentrations were reduced from 1.5 mg/g(DW)to below the safety threshold of 0.5 mg/g.Furthermore,strain ND6 followed the pyridine pathway of nicotine degradation,but the degrading pathway in strain ND16 could not be determined according to genomic analysis and color change.Finally,the abundance of nicotine-degrading genes in tobacco rhizosphere soil was investigated via metagenomic analysis.Five key genes,ndhA,nctB,kdhL,nboR,and dhponh,represent the whole process of nicotine degradation,and their abundance positively correlated with soil nicotine concentrations(p<0.05).In conclusion,various NDB including unknown species live in tobacco soil and degrade nicotine efficiently.Some key nicotine-degrading genes could be used in monitoring nicotine degradation in the environment.The fermentation of compost from tobacco waste is a promising application of efficient NDB.展开更多
基金Project supported by the Industry and Education Combination Innovation Platform of Intelligent Manufacturing and Graduate Joint Training Base at Guizhou University(Grant No.2020-520000-83-01-324061)the National Natural Science Foundation of China(Grant No.61264004)the High-level Creative Talent Training Program in Guizhou Province of China(Grant No.[2015]4015).
文摘Recently,the newly synthesized septuple-atomic layer two-dimensional(2D)material MoSi_(2)N_(4)(MSN)has attracted attention worldwide.Our work delves into the effect of vacancies and external electric fields on the electronic properties of the MSN/graphene(Gr)heterostructure using first-principles calculation.We find that four types of defective structures,N-in,N-out,Si and Mo vacancy defects of monolayer MSN and MSN/Gr heterostructure are stable in air.Moreover,vacancy defects can effectively modulate the charge transfer at the interface of the MSN/Gr heterostructure as well as the work function of the pristine monolayer MSN and MSN/Gr heterostructure.Finally,the application of an external electric field enables the dynamic switching between n-type and p-type Schottky contacts.Our work may offer the possibility of exceeding the capabilities of conventional Schottky diodes based on MSN/Gr heterostructures.
文摘Nicotine,a toxic and addictive alkaloid from tobacco,is an environmental pollutant.However,nicotine-degrading bacteria(NDB)and their function in tobacco planting soil are not fully understood.First,52 NDB strains belonging to seven genera were isolated from tobacco soil.The most dominant genera were Flavobacterium(36.5%),Pseudomonas(30.8%),and Arthrobacter(15.4%),and Chitinophaga and Flavobacterium have not been previously reported.Then,two efficient NDB strains,Arthrobacter nitrophenolicus ND6 and Stenotrophomonas geniculata ND16,were screened and inoculated in the compost fertilizer from tobacco waste.The nicotine concentrations were reduced from 1.5 mg/g(DW)to below the safety threshold of 0.5 mg/g.Furthermore,strain ND6 followed the pyridine pathway of nicotine degradation,but the degrading pathway in strain ND16 could not be determined according to genomic analysis and color change.Finally,the abundance of nicotine-degrading genes in tobacco rhizosphere soil was investigated via metagenomic analysis.Five key genes,ndhA,nctB,kdhL,nboR,and dhponh,represent the whole process of nicotine degradation,and their abundance positively correlated with soil nicotine concentrations(p<0.05).In conclusion,various NDB including unknown species live in tobacco soil and degrade nicotine efficiently.Some key nicotine-degrading genes could be used in monitoring nicotine degradation in the environment.The fermentation of compost from tobacco waste is a promising application of efficient NDB.
