We investigated the influence mechanism of N-doping for dissolved black carbon(DBC)photodegradation of organic pollutants.The degradation performance of N-doped dissolved black carbon(NDBC)for tetracycline(TC)(71%)is ...We investigated the influence mechanism of N-doping for dissolved black carbon(DBC)photodegradation of organic pollutants.The degradation performance of N-doped dissolved black carbon(NDBC)for tetracycline(TC)(71%)is better than that for methylene blue(MB)(28%)under irradiation.These levels are both better than DBC degradation performances for TC(68%)and MB(18%)under irradiation.Reactive species quenching experiments suggest that h and-O,are the main reactive species for NDBC photodegraded TC,while-OH and h*are the main reactive species for NDBC photodegraded MB.-OH is not observed during DBC photodegradation of MB.This is likely because N-doping increases valence-band(VB)energy from 1.55 eV in DBC to 2.04 eV in NDBC;the latter is strong enough to oxidize water to form-OH.Additionally,N-doping increases the DBC band gap of 2.29 to 2.62 eV in NDBC,resulting in a higher separation efficiency of photo-generated electrons-holes in NDBC than in DBC.AIl these factors give NDBC stronger photodegradation performance for TC and MB than DBC.High-performance liquid chromatography-mass spectrometry(HPLC-MS)characterization and toxicity evaluation with the quantitative structure-activity relationship(QSAR)method suggest that TC photodegradation intermediates produced by NDBC have less aromatic structure and are less toxic than those produced by DBC.We adopted a theoretical approach to clarify the relationship between the surface groups of NDBC and the photoactive species produced.Our results add to the understanding of the photochemical behavior of NDBC.展开更多
[Objectives]This study was conducted to investigate the spoilage microorganisms in the storage process of Chinese flowering cabbage.[Methods]Pathogenic bacteria were separated and purified from rotted Chinese flowerin...[Objectives]This study was conducted to investigate the spoilage microorganisms in the storage process of Chinese flowering cabbage.[Methods]Pathogenic bacteria were separated and purified from rotted Chinese flowering cabbage during storage.The gradient dilution culture method and streaking purification method were applied to selectively cultivate spoilage microorganisms for separation and observation.The isolated strains were identified through the ITS and sequence analysis of 16 S rDNA combined with the morphological characteristics and physiological and biochemical properties of the microbes.On the basis of morphology,combined with gene sequence analysis,the isolated pathogenic bacteria A1,A2,A3,and A4 were identified by PCR using the bacterial universal primer 16 S rDNA sequences,and B1 was amplified using the fungal universal primer ITS sequence.The gene sequences obtained by sequencing were subjected to homologous sequence alignment in the NCBI gene library to determine the biological classification of the spoilage bacteria.[Results]The results showed that the four bacteria numbered A1,A2,A3,and A4 were Klebsiella,Acinetobacter baylyi,Staphylococcus epidermidis,and Pseudomonas,respectively.The saprophytic fungus labeled B1 was Streptomyces albus.Re-contacting it to Chinese flowering cabbage caused the cabbage to rot,so it was the main saprophytic fungus that caused the cabbage to rot after picking.Therefore,the main spoilage microorganisms during storage of Chinese flowering cabbage were Klebsiella,A.baylyi,S.epidermidis,Pseudomonas,and S.albus.[Conclusions]This study provides a certain scientific basis and theoretical basis for the storage and preservation of Chinese flowering cabbage.展开更多
基金supported by the Project of the State Key Laboratory of Pollution Control and Resource Reuse Foundation,Nanjing University(No.PCRRF21012)。
文摘We investigated the influence mechanism of N-doping for dissolved black carbon(DBC)photodegradation of organic pollutants.The degradation performance of N-doped dissolved black carbon(NDBC)for tetracycline(TC)(71%)is better than that for methylene blue(MB)(28%)under irradiation.These levels are both better than DBC degradation performances for TC(68%)and MB(18%)under irradiation.Reactive species quenching experiments suggest that h and-O,are the main reactive species for NDBC photodegraded TC,while-OH and h*are the main reactive species for NDBC photodegraded MB.-OH is not observed during DBC photodegradation of MB.This is likely because N-doping increases valence-band(VB)energy from 1.55 eV in DBC to 2.04 eV in NDBC;the latter is strong enough to oxidize water to form-OH.Additionally,N-doping increases the DBC band gap of 2.29 to 2.62 eV in NDBC,resulting in a higher separation efficiency of photo-generated electrons-holes in NDBC than in DBC.AIl these factors give NDBC stronger photodegradation performance for TC and MB than DBC.High-performance liquid chromatography-mass spectrometry(HPLC-MS)characterization and toxicity evaluation with the quantitative structure-activity relationship(QSAR)method suggest that TC photodegradation intermediates produced by NDBC have less aromatic structure and are less toxic than those produced by DBC.We adopted a theoretical approach to clarify the relationship between the surface groups of NDBC and the photoactive species produced.Our results add to the understanding of the photochemical behavior of NDBC.
基金Huanggang Normal University High-level Cultivation Project(04201711903)Youth Talent Project of Hubei Provincial Department of Education(03201718402)。
文摘[Objectives]This study was conducted to investigate the spoilage microorganisms in the storage process of Chinese flowering cabbage.[Methods]Pathogenic bacteria were separated and purified from rotted Chinese flowering cabbage during storage.The gradient dilution culture method and streaking purification method were applied to selectively cultivate spoilage microorganisms for separation and observation.The isolated strains were identified through the ITS and sequence analysis of 16 S rDNA combined with the morphological characteristics and physiological and biochemical properties of the microbes.On the basis of morphology,combined with gene sequence analysis,the isolated pathogenic bacteria A1,A2,A3,and A4 were identified by PCR using the bacterial universal primer 16 S rDNA sequences,and B1 was amplified using the fungal universal primer ITS sequence.The gene sequences obtained by sequencing were subjected to homologous sequence alignment in the NCBI gene library to determine the biological classification of the spoilage bacteria.[Results]The results showed that the four bacteria numbered A1,A2,A3,and A4 were Klebsiella,Acinetobacter baylyi,Staphylococcus epidermidis,and Pseudomonas,respectively.The saprophytic fungus labeled B1 was Streptomyces albus.Re-contacting it to Chinese flowering cabbage caused the cabbage to rot,so it was the main saprophytic fungus that caused the cabbage to rot after picking.Therefore,the main spoilage microorganisms during storage of Chinese flowering cabbage were Klebsiella,A.baylyi,S.epidermidis,Pseudomonas,and S.albus.[Conclusions]This study provides a certain scientific basis and theoretical basis for the storage and preservation of Chinese flowering cabbage.
