Background Mycoplasma pneumonia （M.pneumoniae） is one of the key pathogens of community-acquired pneumonia.A global pandemic of M.pneumoniae has occurred since 2010.The aim of this study was to survey the prevalence...Background Mycoplasma pneumonia （M.pneumoniae） is one of the key pathogens of community-acquired pneumonia.A global pandemic of M.pneumoniae has occurred since 2010.The aim of this study was to survey the prevalence of M.pneumoniae in children in Beijing from 2007-2012.Methods A total of 3 073 clinical specimens were obtained from pediatric patients with respiratory tract infections from January 2007 to December 2012,and examined by nested polymerase chain reaction.PCR products were visualized by 2％ agarose gel electrophoresis,positive products sequenced,and compared with reference sequences in GenBank.Macrolide resistance-associated mutations were also detected for some positive samples.Results Of the 3 073 specimens,588 （19.13％） were positive for M.pneumoniae,12.4％ of which were accompanied by viral infections.Positive rates for M.pneumoniae were highest in 2007 and 2012,showing a significant difference when compared with other years.Infections tended to occur in autumn and winter and positive rates were significantly higher for children aged 3-16.The rate of macrolide resistance-associated mutations was 90.7％,and the predominant mutation was an A→G transition （89.92％） at position 2063 in domain V of the 23S rRNA gene.Conclusions M.pneumoniae outbreaks occurred in 2007 and 2012 in pediatric patients in Beijing,which is consistent with the global prevalence of M.pneumoniae.M.pneumoniae can cause multi-system infections in children,and may be accompanied with viral infections.We determined that school-age children are more susceptible to this disease,particularly in autumn and winter.Gene mutations associated with macrolide resistance were very common in M.pneumoniae-positive specimens during this period in Beijing.展开更多
There is an increasing interest in understanding ambient bioaerosols due to their roles both in health and in climate. Here, we deployed an Ultraviolet Aerodynamic Particle Sizer to monitor viable （fluorescent） bioa...There is an increasing interest in understanding ambient bioaerosols due to their roles both in health and in climate. Here, we deployed an Ultraviolet Aerodynamic Particle Sizer to monitor viable （fluorescent） bioaerosol concentration levels at city centers （highly polluted） and their corresponding suburbs （near pristine） （total 40 locations） in 11 provinces featuring different climate zones in China between July 16 and 28, 2013. The concentration levels of viable bioaerosol particles （BioPM） of 〉0.5 μm were measured, and corresponding percentages of BioPM% （biological fraction of total PM） and BioPM2.5% （biological fraction of PM2.5） in particulate matter （PM） and BioPM, respectively, were determined. For some key cities, indoor viable bioaerosol levels were also obtained. In addition, bacterial structures of the air samples collected across these monitoring locations were studied using pyrosequencing. BioPM concentration levels ranged from 2.1 ×10^4 to 2.4 × 10^5/m3 for city centers [BioPM% = 6.4 % （4-6.3 %）] and 0.5 × 10^4 to 4.7 × 10^5/m3 for suburbs [BioPM% = 10 % （4-8.7 %）]. Distinctive bioaerosol size distribution patterns were observed for different climate zones, e.g., some had fluorescence peaks at 3 μm, while the majority had peaks at 1 μm. Ambient bacterial aerosol community structures were also found different for different geophysical locations. Results suggest that there was a poor overall relationship between PM and BioPM across 40 monitoring locations （R2= 0.081, two-tailed P value = 0.07435）. Generally, city centers had higher PM concentrations than suburbs, but not BioPM and BioPM%. Indoor bioaerosol levels were found at least tenfold higher than those corresponding outdoors. Bacillus was observed to dominate the bacterial aerosol community in the air sample.展开更多
The accurate fault-cause identification for overhead transmission lines supports the operation and maintenance personnel in formulating targeted maintenance strategies and shortening the time of inspecting faulty line...The accurate fault-cause identification for overhead transmission lines supports the operation and maintenance personnel in formulating targeted maintenance strategies and shortening the time of inspecting faulty lines.With the goal of achieving“carbon peak and carbon neutrality”,the schemes for clean energy generation have rapidly developed.Moreover,new energy-consuming equipment has been widely connected to the power grid,and the operating characteristics of the power system have significantly changed.Consequently,these have impacted traditional fault identification methods.Based on the time-frequency characteristics of the fault waveform,new energy-related parameters,and deep learning model,this study proposes a fault identification method suitable for scenarios where a high proportion of new energy is connected to the power grid.Ten parameters related to the causes of transmission line fault and new energy connection scenarios are selected as model characteristic parameters.Further,a fault identification model based on adaptive deep belief networks was constructed,and its effect was verified by field data.展开更多
In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling p...In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling process of microwave pulse into a slot is studied by using the modified FD-TD method, and the dependence of microwave coupling on slot sizes, the carrier frequencies and the polarization directions of the incident waves is analysed. Resonant and enhancement effects which occur in this process are observed. The condition at which the resonant effect takes place is also presented.展开更多
Organoids have attracted great interest for disease modelling,drug discovery and development,and tissue growth and homeostasis investigations.However,lack of standards for quality control has become a prominent obstac...Organoids have attracted great interest for disease modelling,drug discovery and development,and tissue growth and homeostasis investigations.However,lack of standards for quality control has become a prominent obstacle to limit their translation into clinic and other applications.“Human intestinal organoids”is the first guideline on human intestinal organoids in China,jointly drafted and agreed by the experts from the Chinese Society for Cell Biology and its branch society:the Chinese Society for Stem Cell Research.This standard specifies terms and definitions,technical requirements,test methods,inspection rules for human intestinal organoids,which is applicable to quality control during the process of manufacturing and testing of human intestinal organoids.It was originally released by the Chinese Society for Cell Biology on 24 September 2022.We hope that the publication of this standard will guide institutional establishment,acceptance and execution of proper practical protocols and accelerate the international standardization of human intestinal organoids for applications.展开更多
Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(H...Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(HER),but are greatly limited by their low reserves and high cost.Here,we report an interfacial engineering strategy to obtain a promising low-Pt loading catalyst with atomically Pt-doped molybdenum carbide quantum dots decorated on conductive porous carbon(Pt-MoCx@C)for high-rate and stable HER in PEMWE.Benefiting from the strong interfacial interaction between Pt atoms and the ultra-small MoCx quantum dots substrate,the Pt-MoCx catalyst exhibits a high mass activity of 8.00 A·mgPt−1,5.6 times higher than that of commercial 20 wt.%Pt/C catalyst.Moreover,the strong interfacial coupling of Pt and MoCx substrate greatly improves the HER stability of the Pt-MoCx catalyst.Density functional theory studies further confirm the strong metal-support interaction on Pt-MoCx,the critical role of MoCx substrate in the stabilization of surface Pt atoms,as well as activation of MoCx substrate by Pt atoms for improving HER durability and activity.The optimized Pt-MoCx@C catalyst demonstrates>2000 h stability under a water-splitting current of 1000 mA·cm^(−2)when applied to the cathode of a PEM water electrolyzer,suggesting the potential for practical applications.展开更多
Ion-exchange membranes(IEMs)are utilized in numerous established,emergent,and emerging applications for water,energy,and the environment.This article reviews the five different types of IEM selectivity,namely charge,v...Ion-exchange membranes(IEMs)are utilized in numerous established,emergent,and emerging applications for water,energy,and the environment.This article reviews the five different types of IEM selectivity,namely charge,valence,specific ion,ion/solvent,and ion/uncharged solute selectivities.Technological pathways to advance the selectivities through the sorption and migration mechanisms of transport in IEM are critically analyzed.Because of the underlying principles governing transport,efforts to enhance selectivity by tuning the membrane structural and chemical properties are almost always accompanied by a concomitant decline in permeability of the desired ion.Suppressing the undesired crossover of solvent and neutral species is crucial to realize the practical implementation of several technologies,including bioelectrochemical systems,hypersaline electrodialysis desalination,fuel cells,and redox flow batteries,but the ion/solvent and ion/uncharged solute selectivities are relatively understudied,compared to the ion/ion selectivities.Deepening fundamental understanding of the transport phenomena,specifically the factors underpinning structure-property-performance relationships,will be vital to guide the informed development of more selective IEMs.Innovations in material and membrane design offer opportunities to utilize ion discrimination mechanisms that are radically different from conventional IEMs and potentially depart from the putative permeability-selectivity tradeoff.Advancements in IEM selectivity can contribute to meeting the aqueous separation needs of water,energy,and environmental challenges.展开更多
基金This work was supported by the grants from the Beijing Natural Science Foundation （No.7112019） and the Beijing City Talent Training Project Fund （No.20071A0303200118）.
文摘Background Mycoplasma pneumonia （M.pneumoniae） is one of the key pathogens of community-acquired pneumonia.A global pandemic of M.pneumoniae has occurred since 2010.The aim of this study was to survey the prevalence of M.pneumoniae in children in Beijing from 2007-2012.Methods A total of 3 073 clinical specimens were obtained from pediatric patients with respiratory tract infections from January 2007 to December 2012,and examined by nested polymerase chain reaction.PCR products were visualized by 2％ agarose gel electrophoresis,positive products sequenced,and compared with reference sequences in GenBank.Macrolide resistance-associated mutations were also detected for some positive samples.Results Of the 3 073 specimens,588 （19.13％） were positive for M.pneumoniae,12.4％ of which were accompanied by viral infections.Positive rates for M.pneumoniae were highest in 2007 and 2012,showing a significant difference when compared with other years.Infections tended to occur in autumn and winter and positive rates were significantly higher for children aged 3-16.The rate of macrolide resistance-associated mutations was 90.7％,and the predominant mutation was an A→G transition （89.92％） at position 2063 in domain V of the 23S rRNA gene.Conclusions M.pneumoniae outbreaks occurred in 2007 and 2012 in pediatric patients in Beijing,which is consistent with the global prevalence of M.pneumoniae.M.pneumoniae can cause multi-system infections in children,and may be accompanied with viral infections.We determined that school-age children are more susceptible to this disease,particularly in autumn and winter.Gene mutations associated with macrolide resistance were very common in M.pneumoniae-positive specimens during this period in Beijing.
基金supported by the National Natural Science Foundation of China(21277007,21477003,and 41121004)the Ministry of Science and Technology of China(2015DFG92040,2015CB553401)Ministry of Education(20130001110044)
文摘There is an increasing interest in understanding ambient bioaerosols due to their roles both in health and in climate. Here, we deployed an Ultraviolet Aerodynamic Particle Sizer to monitor viable （fluorescent） bioaerosol concentration levels at city centers （highly polluted） and their corresponding suburbs （near pristine） （total 40 locations） in 11 provinces featuring different climate zones in China between July 16 and 28, 2013. The concentration levels of viable bioaerosol particles （BioPM） of 〉0.5 μm were measured, and corresponding percentages of BioPM% （biological fraction of total PM） and BioPM2.5% （biological fraction of PM2.5） in particulate matter （PM） and BioPM, respectively, were determined. For some key cities, indoor viable bioaerosol levels were also obtained. In addition, bacterial structures of the air samples collected across these monitoring locations were studied using pyrosequencing. BioPM concentration levels ranged from 2.1 ×10^4 to 2.4 × 10^5/m3 for city centers [BioPM% = 6.4 % （4-6.3 %）] and 0.5 × 10^4 to 4.7 × 10^5/m3 for suburbs [BioPM% = 10 % （4-8.7 %）]. Distinctive bioaerosol size distribution patterns were observed for different climate zones, e.g., some had fluorescence peaks at 3 μm, while the majority had peaks at 1 μm. Ambient bacterial aerosol community structures were also found different for different geophysical locations. Results suggest that there was a poor overall relationship between PM and BioPM across 40 monitoring locations （R2= 0.081, two-tailed P value = 0.07435）. Generally, city centers had higher PM concentrations than suburbs, but not BioPM and BioPM%. Indoor bioaerosol levels were found at least tenfold higher than those corresponding outdoors. Bacillus was observed to dominate the bacterial aerosol community in the air sample.
基金This work was supported by State Grid Science and Technology Project(B3440821K003).
文摘The accurate fault-cause identification for overhead transmission lines supports the operation and maintenance personnel in formulating targeted maintenance strategies and shortening the time of inspecting faulty lines.With the goal of achieving“carbon peak and carbon neutrality”,the schemes for clean energy generation have rapidly developed.Moreover,new energy-consuming equipment has been widely connected to the power grid,and the operating characteristics of the power system have significantly changed.Consequently,these have impacted traditional fault identification methods.Based on the time-frequency characteristics of the fault waveform,new energy-related parameters,and deep learning model,this study proposes a fault identification method suitable for scenarios where a high proportion of new energy is connected to the power grid.Ten parameters related to the causes of transmission line fault and new energy connection scenarios are selected as model characteristic parameters.Further,a fault identification model based on adaptive deep belief networks was constructed,and its effect was verified by field data.
文摘In this paper, modifications to the finite-difference time-domain(FD-TD) method for modeling microwave pulse coupling into a slot, which is much narrower than one conventional FD-TD cell, are discussed. The coupling process of microwave pulse into a slot is studied by using the modified FD-TD method, and the dependence of microwave coupling on slot sizes, the carrier frequencies and the polarization directions of the incident waves is analysed. Resonant and enhancement effects which occur in this process are observed. The condition at which the resonant effect takes place is also presented.
基金supported by grants from the National Natural Science Foundation of China(31988101 to Y.-G.C.,82173461 To G.Q.H.)Guangdong Basic and Applied Basic Research Foundation(2021A1515111215)to Y.L.W.+2 种基金China Postdoctoral Science Foundation(2021M703230 and 2022T150653)to Y.L.W.National Key R&D Program of China(2018YFA0108400)to T.B.Z.the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16040501)to A.J.M..
文摘Organoids have attracted great interest for disease modelling,drug discovery and development,and tissue growth and homeostasis investigations.However,lack of standards for quality control has become a prominent obstacle to limit their translation into clinic and other applications.“Human intestinal organoids”is the first guideline on human intestinal organoids in China,jointly drafted and agreed by the experts from the Chinese Society for Cell Biology and its branch society:the Chinese Society for Stem Cell Research.This standard specifies terms and definitions,technical requirements,test methods,inspection rules for human intestinal organoids,which is applicable to quality control during the process of manufacturing and testing of human intestinal organoids.It was originally released by the Chinese Society for Cell Biology on 24 September 2022.We hope that the publication of this standard will guide institutional establishment,acceptance and execution of proper practical protocols and accelerate the international standardization of human intestinal organoids for applications.
基金the National Natural Science Foundation of China(Nos.22171287,21901136,51972342,51972345,22105226,and 51872056)Taishan Scholar Project of Shandong Province(Nos.tsqn202103046 and ts20190922)+3 种基金Natural Science Foundation of Shandong Province(Nos.ZR2022QE175 and ZR2019ZD51)Fundamental Research Funds for the Central Universities(Nos.20CX06024A,22CX01002A-1,and 21CX06002A)China Postdoctoral Science Foundation(Nos.2019M650027 and 2019TQ0169)National Natural Science Foundation of Beijing(No.2204082),and Shandong Province Postdoctoral Innovative Talent Support Program(No.SDBX20200004).
文摘Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(HER),but are greatly limited by their low reserves and high cost.Here,we report an interfacial engineering strategy to obtain a promising low-Pt loading catalyst with atomically Pt-doped molybdenum carbide quantum dots decorated on conductive porous carbon(Pt-MoCx@C)for high-rate and stable HER in PEMWE.Benefiting from the strong interfacial interaction between Pt atoms and the ultra-small MoCx quantum dots substrate,the Pt-MoCx catalyst exhibits a high mass activity of 8.00 A·mgPt−1,5.6 times higher than that of commercial 20 wt.%Pt/C catalyst.Moreover,the strong interfacial coupling of Pt and MoCx substrate greatly improves the HER stability of the Pt-MoCx catalyst.Density functional theory studies further confirm the strong metal-support interaction on Pt-MoCx,the critical role of MoCx substrate in the stabilization of surface Pt atoms,as well as activation of MoCx substrate by Pt atoms for improving HER durability and activity.The optimized Pt-MoCx@C catalyst demonstrates>2000 h stability under a water-splitting current of 1000 mA·cm^(−2)when applied to the cathode of a PEM water electrolyzer,suggesting the potential for practical applications.
文摘Ion-exchange membranes(IEMs)are utilized in numerous established,emergent,and emerging applications for water,energy,and the environment.This article reviews the five different types of IEM selectivity,namely charge,valence,specific ion,ion/solvent,and ion/uncharged solute selectivities.Technological pathways to advance the selectivities through the sorption and migration mechanisms of transport in IEM are critically analyzed.Because of the underlying principles governing transport,efforts to enhance selectivity by tuning the membrane structural and chemical properties are almost always accompanied by a concomitant decline in permeability of the desired ion.Suppressing the undesired crossover of solvent and neutral species is crucial to realize the practical implementation of several technologies,including bioelectrochemical systems,hypersaline electrodialysis desalination,fuel cells,and redox flow batteries,but the ion/solvent and ion/uncharged solute selectivities are relatively understudied,compared to the ion/ion selectivities.Deepening fundamental understanding of the transport phenomena,specifically the factors underpinning structure-property-performance relationships,will be vital to guide the informed development of more selective IEMs.Innovations in material and membrane design offer opportunities to utilize ion discrimination mechanisms that are radically different from conventional IEMs and potentially depart from the putative permeability-selectivity tradeoff.Advancements in IEM selectivity can contribute to meeting the aqueous separation needs of water,energy,and environmental challenges.
基金supported by the National Key R&D Program of China(2022YFC2105501)the National Natural Science Foundation of China(32202720)+2 种基金the Agricultural Science and Technology Innovation Program(CAAS-ZDRW202304 and CAAS-ASTIPG2022-IFST-07)the Central Public-interest Scientific Institution Basal Research Fund(1610392020001)the Agricultural Science and Technology Innovation Program(ASTIP)。
