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24篇 您的检索式:作者名="Junke Liu"
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1Mechanism for the formation of the January 2013 heavy haze pollution episode over central and eastern China显示文摘In January 2013,a long-lasting episode of severe haze occurred in central and eastern China,and it attracted attention from all sectors of society.The process and evolution of haze pollution episodes were observed by the'Forming Mechanism and Control Strategies of Haze in China'group using an intensive aerosol and trace gases campaign that simultaneously obtained data at 11 ground-based observing sites in the CARE-China network.The characteristics and formation mechanism of haze pollution episodes were discussed.Five haze pollution episodes were identified in the Beijing-Tianjin-Hebei(Jing-Jin-Ji)area;the two most severe episodes occurred during 9–15 January and 25–31 January.During these two haze pollution episodes,the maximum hourly PM2.5mass concentrations in Beijing were 680 and 530μg m 3,respectively.The process and evolution of haze pollution episodes in other major cities in the Jing-Jin-Ji area,such as Shijiazhuang and Tianjin were almost the same as those observed in Beijing.The external cause of the severe haze episodes was the unusual atmospheric circulation,the depression of strong cold air activities and the very unfavorable dispersion due to geographical and meteorological conditions.However,the internal cause was the quick secondary transformation of primary gaseous pollutants to secondary aerosols,which contributed to the'explosive growth'and'sustained growth'of PM2.5.Particularly,the abnormally high amount of nitric oxide(NOx)in the haze episodes,produced by fossil fuel combustion and vehicle emissions,played a direct or indirect role in the quick secondary transformation of coal-burning sulphur dioxide(SO2)to sulphate aerosols.Furthermore,gaseous pollutants were transformed into secondary aerosols through heterogeneous reactions on the surface of fine particles,which can change the particle’s size and chemical composition.Consequently,the proportion of secondary inorganic ions,such as sulphate and nitrate,gradually increased,which enhances particle hygroscopicity and thereby accelerating formation of the haze pollution.WANG YueSi YAO Li WANG LiLi LIU ZiRui JI DongSheng TANG GuiQian ZHANG JunKe SUN Yang HU Bo XIN JinYuan 2014Science China Earth Sciences2014,57,1:189
2Characteristics of PM_(2.5) pollution in Beijing after the improvement of air quality显示文摘Following the implementation of the strictest clean air policies to date in Beijing,the physicochemical characteristics and sources of PM_(2.5) have changed over the past few years.To improve pollution reduction policies and subsequent air quality further,it is necessary to explore the changes in PM_(2.5) over time.In this study,over one year(2017-2018)field study based on filter sampling(TH-150C;Wuhan Tianhong,China)was conducted in Fengtai District,Beijing,revealed that the annual average PM_(2.5) concentration(64.8±43.1μg/m^3)was significantly lower than in previous years and the highest PM_(2.5) concentration occurred in spring(84.4±59.9μg/m^3).Secondary nitrate was the largest source and accounted for 25.7%of the measured PM_(2.5).Vehicular emission,the second largest source(17.6%),deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants.In addition,the contribution from coal combustion to PM_(2.5) decreased significantly.During weekends,the contribution from EC and NO3−increased whereas the contributions from SO4^2−,OM,and trace elements decreased,compared with weekdays.During the period of residential heating,PM_(2.5) mass decreased by 23.1%,compared with non-heating period,while the contributions from coal combustion and vehicular emission,and related species increased.With the aggravation of pollution,the contribution of vehicular emission and secondary sulfate increased and then decreased,while the contribution of NO3−and secondary nitrate continued to increase,and accounted for 34.0%and 57.5%of the PM_(2.5) during the heavily polluted days,respectively.Xiaojuan Huang Guiqian Tang Junke Zhang Baoxian Liu Chao Liu Jin Zhang Leilei Cong Mengtian Cheng Guangxuan Yan Wenkang Gao Yinghong Wang Yuesi Wang 2021Journal of Environmental Sciences2021,33,2:14
3Characterization of submicron particles during autumn in Beijing,China显示文摘In this study, we performed a highly time-resolved chemical characterization of nonrefractory submicron particles(NR-PM_1) in Beijing by using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer(HR-ToF-AMS). The results showed the average NR-PM_1 mass concentration to be 56.4 ± 58.0 μg/m^3, with a peak at 307.4 μg/m^3. Due to the high frequency of biomass burning in autumn, submicron particles significantly increased in organic content, which accounted for 51% of NR-PM_1 on average. Secondary inorganic aerosols(sulfate + nitrate + ammonium) accounted for 46% of NR-PM_1, of which sulfate,nitrate, and ammonium contributed 15%, 20%, and 11%, respectively. To determine the intrinsic relationships between the organic and inorganic species, we used the positive matrix factorization(PMF) model to merge the high-resolution mass spectra of the organic species and NO+and NO_2^+ions. The PMF analysis separated the mixed organic and nitrate(NO+and NO_2^+) spectra into four organic factors, including hydrocarbon-like organic aerosol(HOA), oxygenated organic aerosol(OOA), cooking organic aerosol(COA), and biomass burning organic aerosol(BBOA), as well as one nitrate inorganic aerosol(NIA) factor. COA(33%) and OOA(30%) contributed the most to the total organic aerosol(OA) mass, followed by BBOA(20%) and HOA(17%). We successfully quantified the mass concentrations of the organic and inorganic nitrates by the NO+and NO2+ions signal in the organic and NIA factors. The organic nitrate mass varied from 0.01-6.8 μg/m^3, with an average of 1.0 ±1.1 μg/m^3, and organic nitrate components accounted for 10% of the total nitrate mass in this observation.Peng Xu Junke Zhang Dongsheng Ji Zirui Liu Guiqian Tang Changsheng Jiang Yuesi Wang 2018Journal of Environmental Sciences2018,30,1:5
4Research Progress of the Antiviral Bioactivities of Natural Flavonoids显示文摘Flavonoids are now considered as an indispensable component in a variety of nutraceutical and pharmaceutical applications.Most recent researches have focused on the health aspects of flavonoids for humans.Especially,different flavonoids have been investigated for their potential antiviral activities,and several natural flavonoids exhibited significant antiviral properties both in vitro and in vivo.This review provides a survey of the literature regarding the evidence for antiviral bioactivities of natural flavonoids,highlights the cellular and molecular mechanisms of natural flavonoids on viruses,and presents the details of most reported flavonoids.Meanwhile,future perspectives on therapeutic applications of flavonoids against viral infections were discussed.Lin Wang Junke Song Ailin Liu Bin Xiao Sha Li Zhang Wen Yang Lu Guanhua Du 2020Natural Products and Bioprospecting2020,10,5:4
5Pharmacokinetic study of gallocatechin-7-gallate from Pithecellobium clypearia Benth. in rats显示文摘The pharmacokinetic profile of gallocatechin-7-gallate(J10688)was studied in rats after intravenous administration.Male and female Sprague-Dawley(SD)rats received 1,3,and 10 mg/kg(i.v.)of J10688 and plasma drug concentrations were determined by a high performance liquid chromatography-mass spectrometry(LC–MS)method.The pharmacokinetic software Data Analysis System(Version 3.0)was used to calculate the pharmacokinetic parameters.For different i.v.doses of J10688,the mean peak plasma concentration(C_0)values ranged from 11.26 to 50.82 mg/L,and mean area under the concentration-time curve(AUC_(0–t))values ranged from 1.75 to 11.80(mg h/L).J10688 lacked dosedependent pharmacokinetic properties within doses between 1 and 10 mg/kg,based on the power model.The method developed in this study was sensitive,precise,and stable.The pharmacokinetic properties of J10688 in SD rats were shown to have rapid distribution and clearance values.These pharmacokinetic results may contribute to an improved understanding of the pharmacological actions of J10688.Chao Li Xiaowei Song Junke Song Xiaocong Pang Zhe Wang Ying Zhao Wenwen Lian Ailin Liu Guanhua Du 2016Acta Pharmaceutica Sinica B2016,6,1:4
6Characterization of Organic Aerosols in Beijing Using an Aerodyne High-Resolution Aerosol Mass Spectrometer显示文摘Fine particle of organic aerosol(OA), mostly arising from pollution, are abundant in Beijing. To achieve a better understanding of the difference in OA in summer and autumn, a high-resolution time-of-flight aerosol mass spectrometer(HRTo F-AMS, Aerodyne Research Inc., USA) was deployed in urban Beijing in August and October 2012. The mean OA mass concentration in autumn was 30 ± 30 μg m-3, which was higher than in summer(13 ± 6.9 μg m-3). The elemental analysis found that OA was more aged in summer(oxygen-to-carbon(O/C) ratios were 0.41 and 0.32 for summer and autumn,respectively). Positive matrix factorization(PMF) analysis identified three and five components in summer and autumn, respectively. In summer, an oxygenated OA(OOA), a cooking-emission-related OA(COA), and a hydrocarbon-like OA(HOA)were indentified. Meanwhile, the OOA was separated into LV-OOA(low-volatility OOA) and SV-OOA(semi-volatile OOA);and in autumn, a nitrogen-containing OA(NOA) was also found. The SOA(secondary OA) was always the most important OA component, accounting for 55% of the OA in the two seasons. Back trajectory clustering analysis found that the origin of the air masses was more complex in summer. Southerly air masses in both seasons were associated with the highest OA loading, while northerly air masses were associated with the lowest OA loading. A preliminary study of OA components,especially the POA(primary OA), in different periods found that the HOA and COA all decreased during the National Day holiday period, and HOA decreased at weekends compared with weekdays.ZHANG Junke WANG Yuesi HUANG Xiaojuan LIU Zirui JI Dongsheng SUN Yang 2015Advances in Atmospheric Sciences2015,32,6:2
7Effect of Adding Microwave Absorber on Structures and Properties of Hypercoal-Based Activated Carbons显示文摘Using lignite-based hypercoal as raw material, KOH as activator and CuO as microwave absorber, we prepared hypercoal-based activated carbons by microwave-assisted activation. The pore structure and the electrochemical performance of the activated carbons were tested, and the effects of adding CuO in the activation reaction process were also investigated. The activated carbons prepared were characterized by nitrogen adsorption-desorption, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The specific surface area and mesoporous ratio of the hypercoal-based activated carbon are 1257 m2/g and 55.4%, respectively. When the activated carbons are used as the electrode materials, the specific capacitance reaches 309 F/g in 3 M KOH electrolyte. In comparison with those prepared without CuO absorber, the specific capacitance increases by 11.6%. It was proved that the addition of microwave absorber in microwave-assisted activation was a low-cost method for rapidly preparing activated carbon, and it could effectively promote the development of the pore structure and improve its electrochemical performance.谢立军 樊丽华 HOU Caixia LIU Junke SUN Zhang 2020Journal of Wuhan University of Technology(Materials Science)2020,35,3:2
8Characterization of submicron aerosols during a month of serious pollution in Beijing,2013显示文摘Zhang Junke Sun Yang Liu Zirui 2014Atmospheric Chemistry and Physics2014,14,6:1
9Alterations and Its Mechanisms of Wnt Signal Pathway in Human High-matastatatic Large Cell Lung Cancer Cell Line L9981 by Transfecting with Nm23-H1 Gene显示文摘Backgroud and Objective Tumor metastasis is not only the malignant marker and characteristics of lung cancer, but also the main cause of failure to cure and lose their life of theJunke FU Zhe WANG Sen WEI Gang CHEN Zhigang LI Jun CHEN Hongyu LIU Zhihao WU Ke XU Qinghua ZHOU 2009中国肺癌杂志2009,12,6:1
10The heaviest particulate air-pollution episodes occurred in northern China in January, 2013: Insights gained from observation显示文摘Dongsheng Ji Liang Li Yuesi Wang Junke Zhang Mengtian Cheng Yang Sun Zirui Liu Lili Wang Guiqian Tang Bo Hu Na Chao Tianxue Wen Hongyan Miao 2014Atmospheric Environment2014,,:1
11An innovative rhein-matrine cocrystal: Synthesis, characterization,formation mechanism and pharmacokinetic study显示文摘Rhein(Rhe), an anthraquinone derivative, exhibits excellent anti-inflammatory effects and other pharmacological activities, but its clinical application remains limited due to poor solubility. The present work aims at the improvement of solubility and oral bioavailability of Rhe through cocrystal formation. For this purpose, Rhe and matrine(Mat) were selected as pharmaceutical ingredient(API) and cocrystal former(CCF), respectively, and the Rhe-Mat cocrystal was synthesized and characterized by single crystal X-ray diffraction(SXRD), powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA), differential scanning calorimetry(DSC). The formation mechanism of Rhe-Mat cocrystal was elucidated by molecular surface electrostatic potential(MSEP). It is worth mentioning that the 50-fold increment of dissolution in vitro was observed in pure water in the form of Rhe-Mat cocrystal. Furthermore, the in vivo studies revealed that Rhe-Mat cocrystal indicated the faster absorption rate and the higher peak blood concentration than the pure Rhe. Hence, it can be concluded that current study successfully improved the solubility and oral bioavailability of Rhe.Hongjuan Wang Dezhi Yang Wen Zhang Junke Song Ningbo Gong Mingchao Yu Shiying Yang Baoxi Zhang Qiwen Liu Guanhua Du Yang Lu 2023Chinese Chemical Letters2023,34,2:0
12An Efficient and Secure Aggregation Encryption Scheme in Edge Computing显示文摘Edge computing is a highly virtualized paradigm that can services the Internet of Things(Io T)devices more efficiently.It is a non-trivial extension of cloud computing,which can not only meet the big data processing requirements of cloud computing,but also collect and analyze distributed data.However,it inherits many security and privacy challenges of cloud computing,such as:authentication and access control.To address these problem,we proposed a new efficient privacy-preserving aggregation scheme for edge computing.Our scheme consists of two steps.First,we divided the data of the end users with the Simulated Annealing Module Partition(SAMP)algorithm.And then,the end sensors and edge nodes performed respectively differential aggregation mechanism with the Differential Aggregation Encryption(DAE)algorithm which can make noise interference and encryption algorithm with trusted authority(TA).Experiment results show that the DAE can preserve user privacy,and has significantly less computation and communication overhead than existing approaches.Junhua Wu Xiaofei Sheng Guangshun Li Kan Yu Junke Liu 2022China Communications2022,19,3:0
13Alterations in the Cytoskeleton and Biological Behavior in Human Lung Cancer Cell Line L9981 by Nm23-H1 gene Transfection显示文摘Objective and Methods The key cause of failure to cure and high mortality in lung cancer. At present, it has been knownZhe WANG Junke FU Zhihao WU Hongyu LIU Jun CHEN Liya SUN Q inghua ZHOU 2009中国肺癌杂志2009,12,6:0
14Single-atom cobalt catalysts for chemoselective hydrogenation of nitroarenes to anilines显示文摘Single-atomic catalysts(SACs)caught considerable attention due to their unique structural properties,complete exposed active site,and 100%atom utilization efficiency with remarkable catalytic activity.Mesoporous single-atomic cobalt catalyst with Co-N_(4) active sites was synthesized by using nitrogen-doped graphene derived from acrylonitrile.Single-atomic cobalt was observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)in Co@Nx-C-800.Notably,the density functional theory(DFT)calculation and the extended X-ray absorption fine structures(EXAFS)fitting results indicate that the coordination structure of Co-N is four-coordinated.In this work,the practical hydrogenation of nitroarenes to anilines enabled by Co@Nx-C-800 was established with excellent yields and selectivity,which proved its advantages and potential applications.Xiaochun Liu Chaoyue Wang Jiaolong Meng Xiaodong Yue Qingyun Wang Jiatian Lu Junke Wang Xicun Wang Yingxiao Zong Xuefeng Jjiang 2023Chinese Chemical Letters2023,34,12:0
15The sparse array elements selection in sparse imaging of circular-array photoacoustic tomography显示文摘Photoacoustic imaging(PAI)has been developed,and photoacoustic computed tomography(PACT)is widely used for in vivo tissue and mouse imaging.Simulated annealing(SA)algorithm solves optimization problems,and compressed sensing(CS)recovers sparse signals from undersampled measurements.We aim to develop an advanced sparse imaging framework for PACT,which invloves the use of SA to¯nd an optimal sparse array element distribution and CS to perform sparse imaging.PACT reconstructions were performed using a dummy and porcine liver phantoms.Compared to traditional sparse reconstruction algorithms,the proposed method recovers signals using few ultrasonic transducer elements,enabling high-speed,low-cost PACT for practical application.Zezheng Qin Yang Liu Junke Chi Yiming Ma Mingjian Sun 2022Journal of Innovative Optical Health Sciences2022,15,5:0
16HIRFL-CSR Control System Progress显示文摘The control system architecture is divided into several parts and three levels. Level I: CPCI architecture for special control processing.Level II: Industrial computer, (PC and SUN SPARC). PCI Modules for general control processing. Level III: Micro-gateway + 31 application modules. The Gateway connects Ethernet to RS-485 and CANBUS or other field-Level II System Progress bus. Run real-time LINUX (NUT) for general control processing.Qiao Weimin, Jing Lan, Ma Yunhai, Gou Shizhe, Lin Jie, Liang Yihai, Liu Ning, Zhang Chunxia Wang Dan, Zhang Shuocheng, Meng Jian, Liu Junke and Zhang Changshuan 2002近代物理研究所和兰州重离子加速器实验室年报:英文版2002,,1:0
17320 kV实验平台新狭缝控制系统显示文摘In the year of 2018,we upgraded the motor control for six group of slits in both high voltage platform and beamline at the 320 kV experimental platform.This new control system is based on Experimental Physics and Industrial Control System(EPICS)[1]and embedded PLC of Beckhoff Ltd.The new control system is 3-layer standard structure.One powerful industry computers from Advantech running CentOS are used as EPICS Input and Output Controller(IOC)with control software running in them.Another IOC running windows operating system is used as Operator Interface(OPI).Embedded PLC in charge of motion control for slits.The communication between embedded PLC and motor drivers is based on EtherCAT,which is a kind of real-time Ethernet.Chang Jianjun Zhang Wei An Shi Liu Xiaojun Wang Pengpeng Liu Junke 2018IMP & HIRFL Annual Report2018,,1:0
18Improving superficial microstructure and properties of the laser-processed ultrathin kerf in Ti-6Al-4V alloy by water-jet guiding显示文摘In the present research,the gas-assisted laser(GAL)and water-jet guided laser(WGL)processing technologies were applied to machine the ultrathin kerf in the wrought Ti-6Al-4V alloy.The microstructure,microhardness,and wear properties of the superficial layer were investigated.The results reveal that the GAL processing could machine the kerf with a high depth-to-width ratio of 12–15,but the increased processing times enhance the depth little.Due to the oxygen entrainment and relatively low heat and mass transferring efficiency,the assisted gas promotes the formation of a scaled recast layer containingβ-Ti phase and oxides,which increases the roughness to 20μm.The WGL processed kerf has a low depth-to-width ratio with a value of 1.9–2.5 and the depth could be increased by increasing the WGL processing times.With the assistance of the water jet,the remelted debris and heat could be eliminated immediately,which restrains the formation of the recast layer and heat-affected zone.The ultrathin oxide outer layer with hundreds of nanometers and ultrafineα-Ti grain inner layer are formed on the surface,which decreases the roughness to 12μm.Compared with the as-received Ti-6Al-4V alloy,the microhardness of GAL processed kerf surface is increased to 382.8 HV accompanied by residual tensile stress,while the microhardness of WGL processed kerf surface is increased to 481.6 HV accompanying with residual compressive stress.In addition,the GAL processing increases the wear rate at room temperature but decreases the wear rate at high temperatures.Comparatively,the WGL processing decreases the wear rate at room and high temperatures,simultaneously.Such wear behaviors could be ascribed to their different superficial microstructures and phase constituents.Yang Chao Yuezhuan Liu Zifa Xu Weixin Xie Li Zhang Wentai Ouyang Haichen Wu Zebin Pan Junke Jiao Shujun Li Guangyi Zhang Wenwu Zhang Liyuan Sheng 2023Journal of Materials Science & Technology2023,,25:0
19Characterization and source identification of submicron aerosol dur ing ser ious haze pollution periods in Beijing显示文摘Submicron aerosol is of extensive concern not only due to its significant impact on air quality but also because it is detrimental to human health.In this study,we investigated the characteristics,sources and chemical processes of submicron aerosol based on realtime online measurements of submicron aerosols(NR-PM 1)during December 2015 at an urban site in Beijing.The average mass concentration of NR-PM 1 was 92.5±84.9μg/m^(3),the hourly maximum was 459.1μg/m^(3) during the entire observation.The organic aerosol(OA)(55%)was the largest contributor to NR-PM 1.The average mass concentration of PAHs was 0.217±0.247μg/m^(3),exhibiting the highest concentration at night and the lowest levels in the daytime.The average mass concentration of organic nitrate was 2.52±2.36μg/m^(3) and that of inorganic nitrate was 7.62±8.22μg/m^(3),accounting for 36%and 64%,respectively,of the total nitrate mass.Positive matrix factorization(PMF)differentiated the OA into five chemical components including LV-OOA,SV-OOA,COA,HOA and CCOA,accounting for 22%,16%,13%,25%and 24%respectively,of the total OA.The average NR-PM 1 mass concentration on the heavy polluted days(HPD)was 182.8±70.2μg/m^(3),which was approximately 9 times that on clean days(CD).The enhanced secondary formation of SNA was evident on HPD,especially the rapid increase of sulfate(23%)and nitrate(19%).Peng Xu Yuan Yang Junke Zhang Wenkang Gao Zirui Liu Bo Hu Yuesi Wang 2022Journal of Environmental Sciences2022,34,2:0
20Implementation of Control System for LECR5显示文摘The LECR5 is a multi-purpose highly charged ion source.The control system is an important subsystem of this facility and a control system has been implemented.Chang Jianjun Zhang Wei An Shi Liu Xiaojun Wang Pengpeng Liu Junke 2019IMP & HIRFL Annual Report2019,,1:0
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