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Rural vehicle emission as an important driver for the variations of summertime tropospheric ozone in the Beijing-Tianjin-Hebei region during 2014-2019

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Journal of Environmental Sciences 2022年第4期34卷 126-135页

作者： Yifei Song Yuanyuan Zhang Junfeng Liu Chenglong Zhang Chengtang liu Pengfei liu Yujing Mu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Tropospheric ozone(O_(3))pollution is increasing in the Beijing-Tianjin-Hebei(BTH)region despite a significant decline in atmospheric fine aerosol particles(PM_(2.5))in recent years.However,the intrinsic reason for the elevation of the regional O_(3)is still unclear.In this study,we analyzed the spatio-temporal variations of tropospheric O_(3)and relevant pollutants(PM_(2.5),NO_(2),and CO)in the BTH region based on monitoring data from the China Ministry of Ecology and Environment during the period of 2014-2019.The results showed that summertime O_(3)concentrations were constant in Beijing(BJ,0.06μg/(m^(3)·year))but increased significantly in Tianjin(TJ,9.09μg/(m^(3)·year))and Hebei(HB,6.06μg/(m3·year)).Distinct O_(3)trends between Beijing and other cities in BTH could not be attributed to the significant decrease in PM_(2.5)(from-5.08 to-6.32μg/(m3·year))and CO(from-0.053 to-0.090 mg/(m^(3)·year))because their decreasing rates were approximately the same in all the cities.The relatively stable O_(3)concentrations during the investigating period in BJ may be attributed to a faster decreasing rate of NO_(2)(BJ:-2.55μg/(m^(3)·year);TJ:-1.16μg/(m^(3)·year);HB:-1.34μg/(m3·year)),indicating that the continued reduction of NOx will be an effective mitigation strategy for reducing regional O_(3)pollution.Significant positive correlations were found between daily maximum8 hr average(MDA8)O_(3)concentrations and vehicle population and highway freight transportation in HB.Therefore,we speculate that the increase in rural NO_(x)emissions due to the increase in vehicle emissions in the vast rural areas around HB greatly accelerates regional O_(3)formation,accounting for the significant increasing trends of O_(3)in HB.

关键词： Tropospheric ozone The Beijing-Tianjin-Hebei region Spatio-temporal trends Rural vehicle emission

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A subspace based method for modelling building’s thermal dynamic in district heating system and parameter extrapolation verification

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Building Simulation 2023年第11期16卷 2145-2158页

作者： junfeng Zhang Lanbin liu Yameng liu University of Science and Technology Beijing 30 Xueyuan RoadBeijing100083China Beijing Nuanliu Technology Co. Ltd.Beijing100083China

The district heating system(DHS)consumes a lot of energy in winter,and its control accuracy needs to be improved urgently.To apply advanced process control(APC)in DHS,the thermal dynamic model of the existing buildings is essential.This paper uses the subspace method which is a data-driven approach for modelling the thermal dynamics of the building.The model’s performance is analyzed using the collected data,and the differences compared to the classical methods are also analyzed.The method reduces the RMSE by about 20%compared with the ARX model for the same complexity.Subsequently,the analysis of the training residuals indicates that the estimate of periodic intra-building disturbance can be obtained by minimizing the training residuals.By introducing the estimated disturbance function,the RMSE on the test set is further reduced by 26%.At the end of the article,a simple parameter extrapolation experiment is conducted,and the result shows that the parameters can be extrapolated to other buildings without large errors.

关键词： modelling district heating system state-space ARX thermal dynamics

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Evaluation of offline sampling for atmospheric C3-C11 non-methane hydrocarbons

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Journal of Environmental Sciences 2022年第3期34卷 132-140页

作者： Zhiguo liu Chengtang liu Zhouming He Yujing Mu Chenglong Zhang Yuanyuan Zhang Pengfei liu Yuzheng Wang Junfeng Liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Regional EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China Clear Science&Technology Co. LtdBeijing 100029China

The concentration variation of C3-C11 non-methane hydrocarbons(NMHCs)collected in several types of commercial flexible bags and adsorption tubes was systematically inves-tigated using a gas chromatography-flame ionization detector(GC-FID)system.The per-centage loss of each NMHC in the polyvinyl fluoride(PVF)bags was less than 5%during a 7-hr storage period;significant NMHCs loss was detected in aluminum foil composite film and fluorinated ethylene propylene bags.The thermal desorption efficiency of NMHCs for adsorption tubes filled Carbopack B and Carboxen1000 sorbents was greater than 95%at 300℃,and the loss of NMHCs in the adsorption tubes during 20-days storage at 4℃was less than 8%.The thermal desorption efficiency for C11 NMHCs in the adsorption tube filled with Carbograph 1 and Carbosieve SⅢabsorbents was less than 40%at 300℃,and pyrolysis of the absorbents at 330℃interfered significantly with the measurements of some alkenes.The loss of alkenes was significant when NMHCs were sampled by cryo-enrichment at-90℃in the presence of O3 for the online NMHC measurements,and negligible for enrichment us-ing adsorption tubes at 25℃.Although O_(3)scrubbers have been widely used to eliminate the influence of O_(3)on NMHC measurements,the loss of NMHCs with carbon numbers greater than 8 was more than 10%.Therefore,PVF bags and adsorption tubes filled Carbopack B and Carboxen1000 sorbents were recommended for the sampling of atmospheric NMHCs.

关键词： Non-methane hydrocarbons(NMHCs) Gas chromatography-flame ionization detector(GC-FID) Offline sampling Adsorption tubes Ozone scrubber

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Characteristics and sources of peroxyacetyl nitrate(PAN)in the rural North China Plain:Results from1-year continuous observations

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Journal of Environmental Sciences 2024年第4期138卷 719-731页

作者： Xin liu Xiaowei He Chenglong Zhang Yifei Song Shuyang Xie Chengtang liu Pengfei liu Yuanyuan Zhang Yujing Mu Junfeng Liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Peroxyacetyl nitrate(PAN)is an important photochemical pollutant in the troposphere,whereas long-term measurements are scarce in rural areas in North China Plain(NCP),resulting in unclear seasonal variations and sources of PAN in rural NCP.In this study,we conducted a 1-year observation of PAN during 2021-2022 at the rural NCP site.The average concentrations of PAN were 1.10,0.75,0.65,and 0.88 ppbv in spring,summer,autumn,and winter,respectively,with a 1-year average of 0.81±0.60 ppbv.Calculations indicate that the loss of PAN through thermal decomposition in summer accounts for 43.2% of the total formed PAN,which is an important reason for the low concentration of PAN in summer.We speculate that since the correlation between PAN and O_(3) in winter is significantly lower than that in other seasons,the observed regional transport of PAN cannot be ignored in winter.Through budget analysis,regional transport accounted for 12.8% and 55.9% of the observed PAN on the spring and winter pollution days,respectively,which showed that regional transport played key roles during the photochemical pollution of the rural NCP in winter.The potential source contribution function revealed that the transported PAN mainly comes from southern Hebei in spring.In winter,the transported PAN was mainly from Langfang,Hengshui,and southern Beijing.Our findings may aid in understanding PAN variations in different seasons in rural areas and highlight the impact of regional transport on the PAN budget.

关键词： Photochemical pollution Peroxyacetyl nitrate(PAN) Seasonal variations Regional transport Rural area

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Structure elucidation,immunomodulatory activity,antitumor activity and its molecular mechanism of a novel polysaccharide from Boletus reticulatus Schaeff

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Food Science and Human Wellness 2023年第2期12卷 647-661页

作者： Siyuan Su Xiang Ding Yiling Hou Binbin liu Zhouhe Du Junfeng Liu Key Laboratory of Southwest China Wildlife Resources Conservation College of Life SciencesChina West Normal UniversityNanchong 637009China Sericultural Research Institute Sichuan Academy of Agricultural SciencesNanchong 637000China College of Environmental Science and Engineering China West Normal UniversityNanchong 637009China

A new water-soluble heteropolysaccharide with a molecular weight of 15 k Da was isolated from the fruiting bodies of Boletus reticulatus Schaeff.Structural characterization results revealed that B.reticulatus Schaeff polysaccharide(BRS-X)had a backbone of 1,6-linkedα-D-galactose and 1,2,6-linkedα-D-galactose which branches were mainly composed of a terminal 4-linkedβ-D-glucose and the ratio of D-galactose and D-glucose was 5:1.Bioactivity assays indicated that BRS-X displayed a strong proliferative activity in T cells and B cells and promoted the secretion of immunoglobulin G(Ig G),Ig E,Ig D and Ig M.In addition,BRS-X could facilitate the proliferation and phagocytosis of RAW264.7 cells and could significantly inhibit the growth of tumors in S180-bearing mice.The results of transcriptome sequencing analysis illustrated that total 46 genes enriched in MAPK and total 34 genes enriched in PI3 K/Akt signaling pathways in BRS-X group.The protein VEGF and VEGFR expression were significantly reduced under the treatment with BRS-X.These findings provide a scientific basis for the edible and medicinal value of BRS-X.

关键词： Boletus reticulatus Schaeff Polysaccharides Structure identification Immunomodulatory activity Antitumor activity

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Focused Widely Linear Beamforming

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Journal of Beijing Institute of Technology 2019年第4期28卷 744-749页

作者： Yougen Xu Junfeng Liu Zhiwen liu School of Information and Electronics Beijing Institute of TechnologyBeijing 100081China

The problem addressed in this paper concerns the extension of widely linear beamforming to the wideband case,developing a wide-focused linear beamformer for the extraction of a wideband second-order(SO)noncircular signal-of-interest(SOI)contaminated by uncorrelated interferences and noise.In the proposed beamformer,the beamforming array observation is first focused to adopt a standard linear minimum variance distortionless response(MVDR)framework.The augmented SOI steering vector then is obtained by estimating the SOI noncircularity parameter with the newly proposed oblique projection with an augmented sparse representation scheme.The covariance matrix of the virtual interference,true interference and noise is further reconstructed using the newly presented complementary spatial spectrum technique.The wideband widely linear spatial filtering is finally realized via MVDR like beamforming.The performance of the proposed beamformer is verified by simulation.

关键词： array signal processing adaptive beamforming direction-of-arrival estimation noncircularity wideband

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PdMoSb trimetallene as high-performance alcohol oxidation electrocatalyst

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Nano Research 2023年第2期16卷 2041-2048页

作者： Junfeng Liu Qiuxia Wang Tong Li Yong Wang Huaming Li Andreu Cabot Institute for Energy Research School of Chemistry and Chemical EngineeringJiangsu UniversityZhenjiang 212013China Catalonia Institute for Energy Research-IREC Sant Adriàde BesòsBarcelona 08930Spain ICREA Pg.Lluís Companys 23Barcelona 08010Spain

Metallenes are an emerging class of two-dimensional(2D)material with outstanding potential in electrocatalysis.Herein,we present a new PdMoSb trimetallene produced by a facile wet-chemistry procedure and tested for the alcohol oxidation reaction.PdMoSb shows an extremely high Pd utilization and superior performance toward ethanol,methanol,and glycerol electro-oxidation compared with PdMo and commercial Pd/C catalysts.Experimental results and density functional theory calculations reveal that the enhanced activity relies not only on the high surface area that characterizes the ultrathin 2D metallene structure,but also on the particular electronic configuration of Sb.Sb facilitates OH−adsorption in the reactive-intermediate pathway and strongly enhances the CO tolerance in the poisoning-intermediate pathway for alcohol oxidation.The excellent alcohol oxidation performance of PdMoSb trimetallene demonstrates the high potential of multimetallenes in the field of electrocatalysis.

关键词： metallene ternary alloy 2D material alcohol oxidation reaction electrocatalysis

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Experimental and Numerical Analysis of the Uniaxial Tensile Properties of F321 Austenitic Stainless Steel at Different Temperatures

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Acta Mechanica Solida Sinica 2022年第3期35卷 409-420页

作者： Meidan liu junfeng Nie Pandong Lin Institute of Nuclear and New Energy Technology Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China

F321 austenitic stainless steel,well known for its excellent corrosion and oxidation resistance,is widely used as a structural component in the pipelines and pumps of light water reactors(LWRs)and generation IV(GenlV)reactors.However,the material failure arising from the high-temperature softening of the 300 series austenitic stainless steels has recently received significant attention.In this study,we conducted uniaxial tensile tests on F321 stainless steel at different temperatures.P\irthermore,we developed a face-centered cubic(FCC)crystal plasticity method emphasizing the temperature factor of the evolution of dislocations inferred by the physical mechanisms at the microscopic level to simulate the polycrystalline mechanical response and model the high-temperature softening phenomenon of F321 austenitic stainless steel.Subsequently,this model was implemented using the ABAQUS finite-element platform.On this basis,the crystal plastic finite-element method(CPFEM)of F321 stainless steel was established.The calculated results were in good agreement with the experimental results,which validated the effectiveness of this numerical method.

关键词： Uniaxial tensile properties F321 austenitic stainless steel Crystal plastic finite-element method

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A Remark on Weighted Cubic Variation of Subfractional Brownian Motion with H<1/6

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Journal of Mathematical Research with Applications 2015年第5期35卷 568-580页

作者： Junfeng Liu Department of Statistics Nanjing Audit University

In this paper,we prove by means of Malliavin calculus the convergence in L2 of some properly renormalized weighted cubic variation of sub-fractional Brownian motion SH with parameter H <16.

关键词： Subfractional Brownian motion Malliavin calculus weighted cubic variation

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Photochemical production of carbonyl sulfide,carbon disulfide and dimethyl sulfide in a lake water

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Journal of Environmental Sciences 2017年第1期29卷 146-156页

作者： Qianqian Du Yujing Mu Chenglong Zhang Junfeng Liu Yuanyuan Zhang Chengtang liu Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Photochemical production of carbonyl sulfide（COS）,carbon disulfide（CS_2） and dimethyl sulfide（DMS） was intensively studied in the water from the Aohai Lake of Beijing city.The lake water was found to be highly supersaturated with COS,CS_2 and DMS,with their initial concentrations of 0.91 ± 0.073 nmol/L,0.55 ± 0.071 nmol/L and 0.37 ± 0.062 nmol/L,respectively.The evident photochemical production of COS and CS_2 in the lake water under irradiation of 365 nm and 302 nm indicated that photochemical production of them might be the reason for their supersaturation.The similar dependence of wavelength and oxygen for photochemical production of COS,CS_2 and DMS implied that they might be from the same precursors.The water cage effect was found to favor COS production but inhibit CS_2and DMS formation,indicating that COS photochemical production was mainly from direct degradation of the precursors and the formation of CS_2 and DMS needed intermediates via combination of carbon-centered radicals and sulfur-centered radicals.The above assumptions were further confirmed by simulation experiments with addition of carbonyls and amino acids（cysteine and methionine）,and the photochemical formation mechanisms for COS,CS_2 and DMS in water were derived from the investigations.

关键词： Photochemical production Carbonyl sulfide Carbon disulfide Dimethyl sulfide Water

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