Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting...Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting the reaction.During the reaction,the presence of oxygen vacancies can extract oxygen from NO,thereby facilitating the cleavage of NO on the catalyst surface.Thus,the formation of oxygen vacancies is key to accelerating the CO-SCR reaction,with different types of oxygen vacancies being more conducive to their generation.In this study,Rh/CeCuO_(x) catalysts were synthesized using the co-crystallization and impregnation methods,and asymmetric oxygen vacancies were induced through hydrogen thermal treatment.This structuralmodification was aimed at regulating the behavior of NO on the catalyst surface.The Rh/Ce0.95Cu0.05O_(x)-H_(2) catalyst exhibited the best performance in CO-SCR,achieving above 90%NO conversion at 162℃.Various characterization techniques showed that the H_(2) treatment effectively reduced some of the CuO and Rh_(2)O_(3),creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface,rather than forming difficult-to-decompose nitrates.This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts.展开更多
Biomass burning(BB)emits carbonaceous aerosols that significantly influence air quality in Southwest China during spring.To further understand the characteristics of spring BB and its original contribution to organic ...Biomass burning(BB)emits carbonaceous aerosols that significantly influence air quality in Southwest China during spring.To further understand the characteristics of spring BB and its original contribution to organic carbon(OC),daily fine particulate matter(PM_(2.5))samples were collected from March to May 2022 in Pu'er,Southwest China.The concentrations of OC,elemental carbon(EC),levoglucosan(Lev),and potassium from BB(K+BB)during the study period ranged from 5.3 to 31.2μg/m^(3),0.86-13.1μg/m^(3),0.06-0.82μg/m^(3),and 0.05-2.88μg/m^(3),respectively.To eliminate the effects of Lev degradation,this study uses the Aging of Air Mass(AAM)index to correct the atmospheric concentration of Lev and combines Bayesian mixture modeling with a molecular tracer method to assess the original contribution of BB to OC.The results indicated that the AAM index was 0.18±0.05,indicating that the degradation of Lev reached 82%.When considering the degradation of levoglucosan in the atmosphere,the primary source of BB aerosols was crop-straw combustion(71.1%),followed by the combustion of certain hardwoods and softwoods(24.9%)and grasses(4.0%).The original contribution of BB to OC was 62.4%,which was much greater than the contribution when levoglucosan degradation(23.7%)was ignored.The air mass inverse trajectories and Moderate Resolution Imaging Spectroradiometer(MODIS)fire hotspots indicated that the BB plume from Southeast Asia during spring could influence PM_(2.5)long-range transport in remote locations,and the contribution could reach 82%in Southwest China.展开更多
The recent concurrent emergence of H5N1,H5N6,and H5N8 avian influenza viruses(AIVs)has led to significant avian mortality globally.Since 2020,frequent human-animal interactions have been documented.To gain insight int...The recent concurrent emergence of H5N1,H5N6,and H5N8 avian influenza viruses(AIVs)has led to significant avian mortality globally.Since 2020,frequent human-animal interactions have been documented.To gain insight into the novel H5 subtype AIVs(i.e.,H5N1,H5N6 and H5N8),we collected 6102 samples from various regions of China between January 2021 and September 2022,and identified 41 H5Nx strains.Comparative analyses on the evolution and biological properties of these isolates were conducted.Phylogenetic analysis revealed that the 41 H5Nx strains belonged to clade 2.3.4.4b,with 13 related to H5N1,19 to H5N6,and 9 to H5N8.Analysis based on global 2.3.4.4b viruses showed that all the viruses described in this study were likely originated from H5N8,exhibiting a heterogeneous evolutionary history between H5N1 and H5N6 during 2015–2022 worldwide.H5N1 showed a higher rate of evolution in 2021–2022 and more sites under positive selection pressure in 2015–2022.The antigenic profiles of the novel H5N1 and H5N6 exhibited notable variations.Further hemagglutination inhibition assay suggested that some A(H5N1)viruses may be antigenically distinct from the circulating H5N6 and H5N8 strains.Mammalian challenge assays demonstrated that the H5N8 virus(21GD001_H5N8)displayed the highest pathogenicity in mice,followed by the H5N1 virus(B1557_H5N1)and then the H5N6 virus(220086_H5N6),suggesting a heterogeneous virulence profile of H5 AIVs in the mammalian hosts.Based on the above results,we speculate that A(H5N1)viruses have a higher risk of emergence in the future.Collectively,these findings unveil a new landscape of different evolutionary history and biological characteristics of novel H5 AIVs in clade 2.3.4.4b,contributing to a better understanding of designing more effective strategies for the prevention and control of novel H5 AIVs.展开更多
Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for con...Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for controlling crop diseases and ensuring sustainable crop production.Cloning disease-resistance(R)genes and understanding their underlying molecular mechanisms provide new genetic resources and strategies for crop breeding.Novel genetic engineering and genome editing tools have accelerated the study and engineering of BSR genes in crops,which is the primary focus of this review.We first summarize recent advances in understanding the plant immune system,followed by an examination of the molecular mechanisms underlying BSR in crops.Finally,we highlight diverse strategies employed to achieve BSR,including gene stacking to combine multiple R genes,multiplexed genome editing of susceptibility genes and promoter regions of executor R genes,editing cis-regulatory elements to fine-tune gene expression,RNA interference,saturation mutagenesis,and precise genomic insertions.The genetic studies and engineering of BSR are accelerating the breeding of disease-resistant cultivars,contributing to crop improvement and enhancing global food security.展开更多
Among the various strategies to achieve C(sp^(3))-C(sp^(3))bond formation,the direct application of alkanes and ethers as coupling partners is an emerging and appealing method that circumvents the need for functionali...Among the various strategies to achieve C(sp^(3))-C(sp^(3))bond formation,the direct application of alkanes and ethers as coupling partners is an emerging and appealing method that circumvents the need for functionalized alkanes.However,it generally requires photocatalytic hydrogen atom transfer(HAT)coupled with nickel catalysis or multiple-step strategies.Herein,we report the direct C(sp^(3))-C(sp^(3))bond formation through C-H insertions using commercially available alkanes/ethers and N-tosylhydrazones under catalyst-free photoinduced conditions.This system is easy to operate and tolerates a diverse range of alkanes and ethers.Additionally,the one-pot reaction for directly coupling alkanes/ethers with aldehydes has also been developed.Furthermore,the gram-scale synthesis and the late-stage modifications demonstrated the potential of this strategy.The mechanism investigations demonstrated that the donor-type free carbene was generated under light irradiation,which then undergoes association and concerted insertion into C-H bonds of alkanes/ethers selectively to access C(sp^(3))-C(sp^(3))bond formation.展开更多
A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM2.5 at three sites ofKunming, a plateau city in South-west C...A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM2.5 at three sites ofKunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions （WSI）, organic and element carbon （OC and EC） in PM2.5 were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 μg.m -3, 17.83±9.57 μg.m-3 and 5.114-4.29 μg.m-3, respectively. They totally accounted for 53.0% of PM2.5. Secondary organic and inorganic aerosols （SOA and SIA） were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM2.5 concentration. The low proportion suggested the primary emission was the main source of PM2.5 in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.展开更多
Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic ...Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic hydrocarbons(PAHs)are susceptible to the influences of meteorological conditions,emissions,and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path.The daily concentrations of total PM_(2.5)-bound PAHs ranged from 0.65 to 80.76 ng/m^(3),with an annual mean of 11.94 ng/m^(3).Here,we found that the concentration of PM_(2.5)-bound PAHs in winter was significantly higher than that in summer,which was mainly due to source and meteorology influence.The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs,while precipitation and low temperature exacerbated this difference.According to the concentration variation trend of PM_(2.5)-bound PAHs and their relationship with meteorological conditions,a new grouping of PAHs is applied,which suggested that PAHs have different environmental fates and migration paths.A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle,but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting.Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_(2.5)-bound PAHs than that in other regions,and the risk in winter was three times than in summer.展开更多
基金supported by the support of the National Natural Science Foundation of China(Nos.22072141,22176185 and 52304429)the National Key Research and Development Program of China(Nos.2022YFB3504200,2021YFB3501900)+4 种基金the Natural Science Foundation of Jiangxi Province for Distinguished Young Scholars(No.20232ACB213004)Jiangxi Provincial Key Research and Development Program(No.20232BBG70012)Jiangxi Provincial Natural Science Foundation(No.20212BAB213032)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2018263)the Research Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences(No.E355C001).
文摘Selective catalytic reduction of NO_(x) with CO(CO-SCR)is a process that purifies both NO and CO pollutants through a catalytic reaction.Specifically,the cleavage of NO on the catalyst surface is crucial for promoting the reaction.During the reaction,the presence of oxygen vacancies can extract oxygen from NO,thereby facilitating the cleavage of NO on the catalyst surface.Thus,the formation of oxygen vacancies is key to accelerating the CO-SCR reaction,with different types of oxygen vacancies being more conducive to their generation.In this study,Rh/CeCuO_(x) catalysts were synthesized using the co-crystallization and impregnation methods,and asymmetric oxygen vacancies were induced through hydrogen thermal treatment.This structuralmodification was aimed at regulating the behavior of NO on the catalyst surface.The Rh/Ce0.95Cu0.05O_(x)-H_(2) catalyst exhibited the best performance in CO-SCR,achieving above 90%NO conversion at 162℃.Various characterization techniques showed that the H_(2) treatment effectively reduced some of the CuO and Rh_(2)O_(3),creating asymmetric oxygen vacancies that accelerated the cleavage of NO on the catalyst surface,rather than forming difficult-to-decompose nitrates.This study offers a novel approach to constructing oxygen vacancies in new CO-SCR catalysts.
基金supported by the Basic Research Key Project of Science and Technology Department of Yunnan Province(No.202401AS070116)the National Natural Science Foundation of China(No.21966016)。
文摘Biomass burning(BB)emits carbonaceous aerosols that significantly influence air quality in Southwest China during spring.To further understand the characteristics of spring BB and its original contribution to organic carbon(OC),daily fine particulate matter(PM_(2.5))samples were collected from March to May 2022 in Pu'er,Southwest China.The concentrations of OC,elemental carbon(EC),levoglucosan(Lev),and potassium from BB(K+BB)during the study period ranged from 5.3 to 31.2μg/m^(3),0.86-13.1μg/m^(3),0.06-0.82μg/m^(3),and 0.05-2.88μg/m^(3),respectively.To eliminate the effects of Lev degradation,this study uses the Aging of Air Mass(AAM)index to correct the atmospheric concentration of Lev and combines Bayesian mixture modeling with a molecular tracer method to assess the original contribution of BB to OC.The results indicated that the AAM index was 0.18±0.05,indicating that the degradation of Lev reached 82%.When considering the degradation of levoglucosan in the atmosphere,the primary source of BB aerosols was crop-straw combustion(71.1%),followed by the combustion of certain hardwoods and softwoods(24.9%)and grasses(4.0%).The original contribution of BB to OC was 62.4%,which was much greater than the contribution when levoglucosan degradation(23.7%)was ignored.The air mass inverse trajectories and Moderate Resolution Imaging Spectroradiometer(MODIS)fire hotspots indicated that the BB plume from Southeast Asia during spring could influence PM_(2.5)long-range transport in remote locations,and the contribution could reach 82%in Southwest China.
基金supported by the Science and Technology Program of Guangdong Province(2022B1111010004,2021B1212030015)China Agriculture Research System of MOF and MARA(CARS-41)China National Animal Disease Surveillance and Epidemiological Survey Program(2021–2025)(No.202111).
文摘The recent concurrent emergence of H5N1,H5N6,and H5N8 avian influenza viruses(AIVs)has led to significant avian mortality globally.Since 2020,frequent human-animal interactions have been documented.To gain insight into the novel H5 subtype AIVs(i.e.,H5N1,H5N6 and H5N8),we collected 6102 samples from various regions of China between January 2021 and September 2022,and identified 41 H5Nx strains.Comparative analyses on the evolution and biological properties of these isolates were conducted.Phylogenetic analysis revealed that the 41 H5Nx strains belonged to clade 2.3.4.4b,with 13 related to H5N1,19 to H5N6,and 9 to H5N8.Analysis based on global 2.3.4.4b viruses showed that all the viruses described in this study were likely originated from H5N8,exhibiting a heterogeneous evolutionary history between H5N1 and H5N6 during 2015–2022 worldwide.H5N1 showed a higher rate of evolution in 2021–2022 and more sites under positive selection pressure in 2015–2022.The antigenic profiles of the novel H5N1 and H5N6 exhibited notable variations.Further hemagglutination inhibition assay suggested that some A(H5N1)viruses may be antigenically distinct from the circulating H5N6 and H5N8 strains.Mammalian challenge assays demonstrated that the H5N8 virus(21GD001_H5N8)displayed the highest pathogenicity in mice,followed by the H5N1 virus(B1557_H5N1)and then the H5N6 virus(220086_H5N6),suggesting a heterogeneous virulence profile of H5 AIVs in the mammalian hosts.Based on the above results,we speculate that A(H5N1)viruses have a higher risk of emergence in the future.Collectively,these findings unveil a new landscape of different evolutionary history and biological characteristics of novel H5 AIVs in clade 2.3.4.4b,contributing to a better understanding of designing more effective strategies for the prevention and control of novel H5 AIVs.
基金supported by Biological Breeding-National Science and Technology Major Projects(2023ZD04070)the Key R&D Program of Hubei Province(2023BBB171)+3 种基金the National Key R&D Program of China(2022YFA1304402)Fundamental Research Funds for the Central Universities(2662023PY006,AML2023A05,2662024ZKPY001)(to G.L.)supported by the Fundamental Research Funds for the Central Universities(2662023PY006)(to K.X.)supported by the National Natural Science Foundation of China(32172373 and 32293243)(to G.L.and K.X.,respectively)and Hubei Hongshan Laboratory.
文摘Plant diseases,caused by a wide range of pathogens,severely reduce crop yield and quality,posing a significant threat to global food security.Developing broad-spectrum resistance(BSR)in crops is a key strategy for controlling crop diseases and ensuring sustainable crop production.Cloning disease-resistance(R)genes and understanding their underlying molecular mechanisms provide new genetic resources and strategies for crop breeding.Novel genetic engineering and genome editing tools have accelerated the study and engineering of BSR genes in crops,which is the primary focus of this review.We first summarize recent advances in understanding the plant immune system,followed by an examination of the molecular mechanisms underlying BSR in crops.Finally,we highlight diverse strategies employed to achieve BSR,including gene stacking to combine multiple R genes,multiplexed genome editing of susceptibility genes and promoter regions of executor R genes,editing cis-regulatory elements to fine-tune gene expression,RNA interference,saturation mutagenesis,and precise genomic insertions.The genetic studies and engineering of BSR are accelerating the breeding of disease-resistant cultivars,contributing to crop improvement and enhancing global food security.
基金supported by the Chenguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22CGA51,to Yu Zhang)the Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(2024Y08,to Yu Zhang)+5 种基金the National Natural Science Foundation of China(82404460,to Yu Zhang82141203,82003624,to Wei-Dong Zhang)the National Key Research and Development Program of China(2022YFC3502000,to Wei-Dong Zhang)the Shanghai Municipal Science and Technology Major Project(ZD2021CY001,to Wei-Dong Zhang)the General Project of Shanghai Natural Science Foundation(24ZR1466700,to Yu Zhang)the Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine(ZYYCXTDD202004,to Wei-Dong Zhang)。
文摘Among the various strategies to achieve C(sp^(3))-C(sp^(3))bond formation,the direct application of alkanes and ethers as coupling partners is an emerging and appealing method that circumvents the need for functionalized alkanes.However,it generally requires photocatalytic hydrogen atom transfer(HAT)coupled with nickel catalysis or multiple-step strategies.Herein,we report the direct C(sp^(3))-C(sp^(3))bond formation through C-H insertions using commercially available alkanes/ethers and N-tosylhydrazones under catalyst-free photoinduced conditions.This system is easy to operate and tolerates a diverse range of alkanes and ethers.Additionally,the one-pot reaction for directly coupling alkanes/ethers with aldehydes has also been developed.Furthermore,the gram-scale synthesis and the late-stage modifications demonstrated the potential of this strategy.The mechanism investigations demonstrated that the donor-type free carbene was generated under light irradiation,which then undergoes association and concerted insertion into C-H bonds of alkanes/ethers selectively to access C(sp^(3))-C(sp^(3))bond formation.
基金This study was fimded by the Society Development Science Plan in Yunnan （2012CA016）, the National Natural Science Foundation of China （Grant Nos. 21567012 and 21207055）.
文摘A sampling campaign including summer, autumn and winter of 2014 and spring of 2015 was accomplished to obtain the characteristic of chemical components in PM2.5 at three sites ofKunming, a plateau city in South-west China. Nine kinds of water-soluble inorganic ions （WSI）, organic and element carbon （OC and EC） in PM2.5 were analyzed by ion chromatography and thermal optical reflectance method, respectively. Results showed that the average concentrations of total WSI, OC and EC were 22.85±10.95 μg.m -3, 17.83±9.57 μg.m-3 and 5.114-4.29 μg.m-3, respectively. They totally accounted for 53.0% of PM2.5. Secondary organic and inorganic aerosols （SOA and SIA） were also assessed by the minimum ratio of OC/EC, nitrogen and sulfur oxidation ratios. The annual average concentrations of SOA and SIA totally accounted for 28.3% of the PM2.5 concentration. The low proportion suggested the primary emission was the main source of PM2.5 in Kunming. However, secondary pollution in the plateau city should also not be ignorable, due to the appropriate temperature and strong solar radiation, which can promote the atmospheric photochemical reactions.
基金supported by the National Key R&D Projects of China(No.2019YFC0214405)the National Natural Science Foundation of China(Nos.21966016,21667014).
文摘Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic hydrocarbons(PAHs)are susceptible to the influences of meteorological conditions,emissions,and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path.The daily concentrations of total PM_(2.5)-bound PAHs ranged from 0.65 to 80.76 ng/m^(3),with an annual mean of 11.94 ng/m^(3).Here,we found that the concentration of PM_(2.5)-bound PAHs in winter was significantly higher than that in summer,which was mainly due to source and meteorology influence.The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs,while precipitation and low temperature exacerbated this difference.According to the concentration variation trend of PM_(2.5)-bound PAHs and their relationship with meteorological conditions,a new grouping of PAHs is applied,which suggested that PAHs have different environmental fates and migration paths.A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle,but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting.Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_(2.5)-bound PAHs than that in other regions,and the risk in winter was three times than in summer.
