Carbon dioxide(CO_(2))emissions from aquatic ecosystems are important components of the global carbon cycle,yet the CO_(2)emissions from coastal reservoirs,especially in developing countries where urbanization and rap...Carbon dioxide(CO_(2))emissions from aquatic ecosystems are important components of the global carbon cycle,yet the CO_(2)emissions from coastal reservoirs,especially in developing countries where urbanization and rapid land use change occur,are still poorly understood.In this study,the spatiotemporal variations in CO_(2)concentrations and fluxes were investigated in Wenwusha Reservoir located in the southeast coast of China.Overall,the mean CO_(2)concentration and flux across the whole reservoir were 41.85±2.03μmol/L and 2.87±0.29 mmol/m2/h,respectively,and the reservoir was a consistent net CO_(2)source over the entire year.The land use types and urbanization levels in the reservoir catchment significantly affected the input of exogenous carbon towater.The mean CO_(2)fluxwasmuch higher from waters adjacent to the urban land(5.05±0.87 mmol/m2/hr)than other land use types.Sites with larger input of exogenous substance via sewage discharge and upstream runoff were often the hotspots of CO_(2)emission in the reservoir.Our results suggested that urbanization process,agricultural activities,and large input of exogenous carbon could result in large spatial heterogeneity of CO_(2)emissions and alter the CO_(2)biogeochemical cycling in coastal reservoirs.Further studies should characterize the diurnal variations,microbial mechanisms,and impact of meteorological conditions on reservoir CO_(2)emissions to expand our understanding of the carbon cycle in aquatic ecosystems.展开更多
Solution processes have shown excellent potential for application to the growth of single-crystal materials. We have developed a confined-solution method for the preparation of single crystals with a controlled morpho...Solution processes have shown excellent potential for application to the growth of single-crystal materials. We have developed a confined-solution method for the preparation of single crystals with a controlled morphology. By confining the precursor solution within a micrometer-thick cavity and then controlling the saturation by adjusting the temperature gradient and fluid flow, high-quality CHBNH3PbBr3 single crystals with tunable morphologies could be obtained. The morphologies of the CH3NH3PbBr3 can be adjusted from sub-square centimeter-scale thin sheets that are square or rectangular, to one-dimensional wires with lengths in the order of centimeters, simply by changing the temperature. The thicknesses of the CH3NH3PbBr3 sheets could be adjusted from hundreds of nanometers to tens of microns. The CH3NHBPbBr3 sheets feature very clean surfaces with an atomic-scale roughness. This simple strategy provides a means of growing high-quality single crystals with clean surfaces, which realize high levels of performance when applied to devices.展开更多
Objective: The aim of this study was to determine the etiology and prevalence of pediatric CAP in Beijing using a real-time polymerase chain reaction (PCR) technique. Methods: Between February 15, 2011 and January 18...Objective: The aim of this study was to determine the etiology and prevalence of pediatric CAP in Beijing using a real-time polymerase chain reaction (PCR) technique. Methods: Between February 15, 2011 and January 18, 2012, 371 pediatric patients with CAP were enrolled at Beijing Children's Hospital. Sixteen respiratory viruses and two bacteria were detected from tracheal aspirate specimens using commercially available multiplex real-time reverse transcription PCR (RT-PCR) kits. Results: A single viral pathogen was detected in 35.3%of enrolled patients, multiple viruses in 11.6%, and virus/bacteria co-infection in 17.8%. In contrast, only 6.5%of patients had a single bacterial pathogen and 2.2%were infected with multiple bacteria. The etiological agent was unknown for 26.7% of patients. The most common viruses were respiratory syncytial virus (RSV) (43.9%), rhinovirus (14.8%), parainfluenza virus (9.4%), and adenovirus (8.6%). In patients under three years of age, RSV (44.6%), rhinovirus (12.8%), and Streptococcus pneumoniae (9.9%) were the most frequent pathogens. In children aged 3e7 years, S. pneumoniae (38.9%), RSV (30.6%), Haemophilus influenzae (19.4%), and adenovirus (19.4%) were most prevalent. Finally in children over seven years, RSV (47.3%), S. pneumoniae (41.9%), and rhinovirus (21.5%) infections were most frequent. Conclusions: Viral pathogens, specifically RSV, were responsible for the majority of CAP in pediatric patients. However, both S. pneumoniae and H. influenzae contributed as major causes of disease. Commercially available multiplexing real-time PCR allowed for rapid detection of the etiological agent. Copyright ? 2015, Chinese Medical Association Production. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).展开更多
Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.Th...Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.This work developed a scalable and feasible method to assemble SWCNT thin films on water surfaces based on Marangoni flow induced by surface tension gradient.The films possess a large area of 40 cm×30 cm(extensible),a tunable thickness of 15∼150 nm,a high transparency of up to 96%,and a decent conductivity.They are ready to be directly transferred to various substrates,including flexible ones.Flexible strain sensors were fabricated with the films on flexible substrates.These sensors worked with high sensitivity and repeatability.By realizing multi-functional human motion sensing,including responding to voices,monitoring artery pulses,and detecting knuckle and muscle actions,the assembled SWCNT films demonstrated the potential for application in smart devices.展开更多
In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reu...In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reusable plasmonic substrates that ensures single molecule sensitivity and acquires intrinsic information of molecules.Here,we proposed a strategy to utilize single-walled carbon nanotubes(SWNTs)to construct SERS substrates.Employing ultrasonic spray pyrolysis,we prepared in situ polyhedral gold nanocrystals closely spaced and attached to nanotubes,ensuring valid hot spots formed along the tube-walls.With such SERS substrates,we proved the single molecule detection by the statistical analysis based on the natural abundance of isotopes.Since SWNTs provide non-chemical bonding adsorption sites,our SERS substrates are easily reusable and have a unique advantage of preserving the intrinsic property of the molecules detected.Using SWNTs to build SERS substrates may become a powerful general strategy in various static and dynamic studies of single molecules.展开更多
基金supported by the National Science Foundation of China(Nos.41801070,41671088)the National Science Foundation of Fujian Province(No.2020J01136)+2 种基金2020 Innovation Training Programme Project for Fujian Normal University Student’s(No.cxxl-2020270)the Research Grants Council of the Hong Kong Special Administrative Region,China(Nos.CUHK458913,14302014,14305515)the CUHK Direct Grant(No.SS15481),Open Research Fund Program of Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control(No.KHK1806),a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)and the Minjiang Scholar Programme.
文摘Carbon dioxide(CO_(2))emissions from aquatic ecosystems are important components of the global carbon cycle,yet the CO_(2)emissions from coastal reservoirs,especially in developing countries where urbanization and rapid land use change occur,are still poorly understood.In this study,the spatiotemporal variations in CO_(2)concentrations and fluxes were investigated in Wenwusha Reservoir located in the southeast coast of China.Overall,the mean CO_(2)concentration and flux across the whole reservoir were 41.85±2.03μmol/L and 2.87±0.29 mmol/m2/h,respectively,and the reservoir was a consistent net CO_(2)source over the entire year.The land use types and urbanization levels in the reservoir catchment significantly affected the input of exogenous carbon towater.The mean CO_(2)fluxwasmuch higher from waters adjacent to the urban land(5.05±0.87 mmol/m2/hr)than other land use types.Sites with larger input of exogenous substance via sewage discharge and upstream runoff were often the hotspots of CO_(2)emission in the reservoir.Our results suggested that urbanization process,agricultural activities,and large input of exogenous carbon could result in large spatial heterogeneity of CO_(2)emissions and alter the CO_(2)biogeochemical cycling in coastal reservoirs.Further studies should characterize the diurnal variations,microbial mechanisms,and impact of meteorological conditions on reservoir CO_(2)emissions to expand our understanding of the carbon cycle in aquatic ecosystems.
文摘Solution processes have shown excellent potential for application to the growth of single-crystal materials. We have developed a confined-solution method for the preparation of single crystals with a controlled morphology. By confining the precursor solution within a micrometer-thick cavity and then controlling the saturation by adjusting the temperature gradient and fluid flow, high-quality CHBNH3PbBr3 single crystals with tunable morphologies could be obtained. The morphologies of the CH3NH3PbBr3 can be adjusted from sub-square centimeter-scale thin sheets that are square or rectangular, to one-dimensional wires with lengths in the order of centimeters, simply by changing the temperature. The thicknesses of the CH3NH3PbBr3 sheets could be adjusted from hundreds of nanometers to tens of microns. The CH3NHBPbBr3 sheets feature very clean surfaces with an atomic-scale roughness. This simple strategy provides a means of growing high-quality single crystals with clean surfaces, which realize high levels of performance when applied to devices.
文摘Objective: The aim of this study was to determine the etiology and prevalence of pediatric CAP in Beijing using a real-time polymerase chain reaction (PCR) technique. Methods: Between February 15, 2011 and January 18, 2012, 371 pediatric patients with CAP were enrolled at Beijing Children's Hospital. Sixteen respiratory viruses and two bacteria were detected from tracheal aspirate specimens using commercially available multiplex real-time reverse transcription PCR (RT-PCR) kits. Results: A single viral pathogen was detected in 35.3%of enrolled patients, multiple viruses in 11.6%, and virus/bacteria co-infection in 17.8%. In contrast, only 6.5%of patients had a single bacterial pathogen and 2.2%were infected with multiple bacteria. The etiological agent was unknown for 26.7% of patients. The most common viruses were respiratory syncytial virus (RSV) (43.9%), rhinovirus (14.8%), parainfluenza virus (9.4%), and adenovirus (8.6%). In patients under three years of age, RSV (44.6%), rhinovirus (12.8%), and Streptococcus pneumoniae (9.9%) were the most frequent pathogens. In children aged 3e7 years, S. pneumoniae (38.9%), RSV (30.6%), Haemophilus influenzae (19.4%), and adenovirus (19.4%) were most prevalent. Finally in children over seven years, RSV (47.3%), S. pneumoniae (41.9%), and rhinovirus (21.5%) infections were most frequent. Conclusions: Viral pathogens, specifically RSV, were responsible for the majority of CAP in pediatric patients. However, both S. pneumoniae and H. influenzae contributed as major causes of disease. Commercially available multiplexing real-time PCR allowed for rapid detection of the etiological agent. Copyright ? 2015, Chinese Medical Association Production. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
基金supported by National Natural Science Foundation of China(22120102004,21631002)Ministry of Science and Technology of China(2016YFA0201904)+3 种基金Shenzhen KQTD Project(KQTD20180411143400981)Beijing National Laboratory for Molecular Sciences(BNLMS-CXTD-202001)JSPS KAKENHI(JP20H00220)and by JST,CREST(JPMJCR20B5),Japan,。
文摘Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.This work developed a scalable and feasible method to assemble SWCNT thin films on water surfaces based on Marangoni flow induced by surface tension gradient.The films possess a large area of 40 cm×30 cm(extensible),a tunable thickness of 15∼150 nm,a high transparency of up to 96%,and a decent conductivity.They are ready to be directly transferred to various substrates,including flexible ones.Flexible strain sensors were fabricated with the films on flexible substrates.These sensors worked with high sensitivity and repeatability.By realizing multi-functional human motion sensing,including responding to voices,monitoring artery pulses,and detecting knuckle and muscle actions,the assembled SWCNT films demonstrated the potential for application in smart devices.
基金supported by the National key R&D Progrom of China(No.2016YFA0201904)the National Natural Science Foundation of China(Nos.21873008 and 21631002)+1 种基金Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXTD-202001)Shenzhen Basic Research Project(No.JCYJ20170817113121505).
文摘In single molecule study,surface-enhanced Raman scattering(SERS)has the advantage of specifically providing structural information of the molecules targeted.The main challenge in single molecule SERS is developing reusable plasmonic substrates that ensures single molecule sensitivity and acquires intrinsic information of molecules.Here,we proposed a strategy to utilize single-walled carbon nanotubes(SWNTs)to construct SERS substrates.Employing ultrasonic spray pyrolysis,we prepared in situ polyhedral gold nanocrystals closely spaced and attached to nanotubes,ensuring valid hot spots formed along the tube-walls.With such SERS substrates,we proved the single molecule detection by the statistical analysis based on the natural abundance of isotopes.Since SWNTs provide non-chemical bonding adsorption sites,our SERS substrates are easily reusable and have a unique advantage of preserving the intrinsic property of the molecules detected.Using SWNTs to build SERS substrates may become a powerful general strategy in various static and dynamic studies of single molecules.
