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Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

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Journal of Environmental Sciences 2018年第9期30卷 32-44页

作者： Yanqin Ren Gehui Wang Jianjun Li Can Wu Cong Cao Jiayuan Wang Lu Zhang Fan Meng Hong Li State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710061 China. Key Laboratory of Geographic Information Science of the Ministry of Education School of Geographic Sciences East China Normal UniversityShanghai 200041 China Center of Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China University of Chinese Academy of Sciences Beijin9 100049 China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences Beijing 100012 China

size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured using gas chromatography/mass spectrometry （GC/MS）. Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations （R^2 = 0.44-0.90） between BSOA and sulfate were found at the six sites, suggesting that anthropogenic pollution （i.e., sulfate） could enhance SOA formation, because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode （〈3.3 μm） except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse （〉3.3 μm） modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.

关键词： Biogenic secondary organic aerosols Photochemical oxidation Seasonal and spatial variations size distribution Sulfate

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size distribution of sulfur species in fine and ultrafine aerosol particles using sulfur K-edge XANES

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Chinese Physics C 2009年第11期33卷 965-968页

作者：林俊包良满刘卫李燕李玉兰马陈燕赵屹东 Shanghai Institute of Applied Physics Chinese Academy of Sciences Institute of High Energy Physics Chinese Academy of Sciences

The sulfur species existing in different size aerosol particles were determined based on the ＇white line＇ energy shift and the features of post edge structure of sulfur K-edge XANES （X-ray Absorption Near Edge Structure）. The results indicated that sulfates were dominant sulfur species in aerosol particles. However, small amount of reductive sulfur species were also found in the ultrafine aerosol particles（〈0.1 μm）. Sulfates in aerosols mostly exhibited as （NH4）2SO4 and gypsum. than 0.952 μm, while gypsum was the dominant sulfate Most （NH4）2SO4 distributed in aerosol particles finer in coarse aerosols.

关键词： sulfur species aerosol size distribution XANES

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Chemical composition and size distribution of secondary organic aerosol formed from the photooxidation of isoprene

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Journal of Environmental Sciences 2009年第11期21卷 1525-1531页

作者： LIU Xianyun, ZHANG Weijun, WANG Zhenya, ZHAO Weixiong, TAO Ling, YANG Xibin Laboratory of Environmental Spectroscopy, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China. Laboratory of Environmental Spectroscopy Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Hefei 230031 China

Photooxidation of isoprene leads to the formation of secondary organic aerosol （SOA）. In this study, the chemical composition of SOA formed from OH-initiated photooxidation of isoprene has been investigated with gas chromatography/mass spectrometry （GC/MS） and a home-made aerosol time-of-fiight mass spectrometer. Sampling particles generated in a home-made smog chamber. The size distribution of SOA particles was detected by a TSI 3321 aerodynamic particle size spectrometer in real time. Results showed that SOA created by isoprene photooxidation was predominantly in the form of fine particles, which have diameters less than 2.5 μm. The obtained mass spectra of individual particles show that products of the OH-initiated oxidation of isoprene contain methyl vinyl ketone, methacrolein, formaldehyde, and some other hydroxycarbonyls. The possible reaction mechanisms leading to these products were also discussed.

关键词： secondary organic aerosols isoprene aerosol time-of-fiight mass spectrometer smog chamber size distribution

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size distribution of Particles Emitted from Liquefied Natural Gas Fueled Engine

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Journal of Beijing Institute of Technology 2008年第4期17卷 410-414页

作者：王军方葛蕴珊何超谭建伟尤可为 School of Mechanical and Vehicular Engineering Beijing Institute of Technology China Automotive Technology & Research Center

The results of measurements conducted to determine the number and mass concentration of particles emitted from the liquefied natural gas （LNG） fueled spark ignition engines are presented. Particle size distributions were measured at different speeds, different loads and ESC cycles. The nanoparticles with diameter smaller than 39 nm, measured by the electrical low-pressure impactor （ELPI）, are dominant in number con- centration that is nearly 92.7 % of the total number of the emitted particles at the peak point. As for the mass of emission particle, it is shown that the mass of the particles greater than 1.2μm is more than 65 % that of the emitted particles.

关键词： particle matter emission size distribution number mass

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An experimental study on size distribution and zeta potential of bulk cavitation nanobubbles

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International Journal of Minerals,Metallurgy and Materials 2020年第2期27卷 152-161页

作者： Xu-yu Zhang Qian-shuai Wang Zhong-xian Wu Dong-ping Tao School of Mining Engineering University of Science and Technology LiaoningAnshan 114051China School of Resources and Environmental Engineering Shandong University of TechnologyZibo 255049China

Nanobubble flotation technology is an important research topic in the field of fine mineral particle separation.The basic characteristics of nanobubbles,including their size,concentration,surface zeta potential,and stability have a significant impact on the nanobubble flotation performance.In this paper,bulk nanobubbles generated based on the principle of hydrodynamic cavitation were investigated to determine the effects of different parameters(e.g.,surfactant(frother)dosage,air flow,air pressure,liquid flow rate,and solution pH value)on their size distribution and zeta potential,as measured using a nanoparticle analyzer.The results demonstrated that the nanobubble size decreased with increasing pH value,surfactant concentration,and cavitation-tube liquid flow rate but increased with increasing air pressure and increasing air flow rate.The magnitude of the negative surface charge of the nanobubbles was positively correlated with the pH value,and a certain relationship was observed between the zeta potential of the nanobubbles and their size.The structural parameters of the cavitation tube also strongly affected the characteristics of the nanobubbles.The results of this study offer certain guidance for optimizing the nanobubble flotation technology.

关键词： nanobubble hydrodynamic cavitation zeta potential size distribution

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Effects of high pressure roller grinding on size distribution of vanadium-titanium magnetite concentrate particles and improvement of green pellet strength

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Journal of Iron and Steel Research(International) 2017年第3期24卷 266-272页

作者： Feng Chen Yu-feng Guo Tao Jiang Fu-qiang Zheng Shuai Wang Ling-zhi Yang School of Minerals Processing and Bioengineering Central South University Changsha 410083 Hunan China

The vanadium-titanium magnetite concentrate from Panxi region of China was pretreated by high pressure roller grinding（ HPRG） and then used in pelletization. size distribution change of the vanadiumtitanium magnetite concentrate after HPRG and the improvement of its green pellet strength were investigated. The results indicated that,besides the increase of fine particles,the vanadium-titanium magnetite concentrate after HPRG had a smaller size ratio of fine particle to coarse particle of 0. 126,meaning a lower porosity,compared with the size ratio of raw material of 0. 157. The concentrate particles were more closely packed when there was a smaller size ratio of fine particle to coarse particle. The particle packing in the green pellets was closer after HPRG,which strengthened the green pellets with an average drop number of 5. 1（ drop height of 0. 5 m） and average compressive strength of 13. 1 N per pellet of 11 mm in diameter.

关键词： High pressure roller grinding Particle packing size distribution size ratio Green pellet strength

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The size distribution of airborne bacteria and human pathogenic bacteria in a commercial composting plant

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Frontiers of Environmental Science & Engineering 2021年第3期15卷 87-96页

作者： Min Gao Ziye Yang Yajie Guo Mo Chen Tianlei Qiu Xingbin Sun Xuming Wang Beijing Key Laboratory of Agricultural Genetic Resources and Biotechnology Beijing Agro-Biotechnology Research CenterBeijing Academy of Agriculture and Forestry SciencesBeijing 100097China College of Forestry Northeast Forestry UniversityHarbin 150040China

Composting plants are regarded as one of the important sources of environmental bioaerosols.However,limitations in the size distribution of airborne bacteria have prevented our comprehensive understanding of their risk to human health and their dispersal behavior.In this study,different sizes of airborne bacteria were collected using an eight-stage impactor from a full-scale composting facility.size-related abundance and communities of airborne bacteria as well as human pathogenic bacteria(HPB)were investigated using 16S rRNA gene sequencing coupled with droplet digital PCR.Our results indicate that the bacterial concentrations from the eight stages were approximately 10^(4)-105copies/m^(3).Although no statistical correlation was detected between the particle size and the Shannon index,the influence of size on bacterial lineages was observed in both composting and packaging areas.For airborne bacteria from different stages,the dominant phyla were Firmicutes,Proteobacteria,and Actinobacteria,and the dominant genera was Bacillus.Seven out of eight HPB with a small geometric mean aerodynamic diameter had a high concentration in composting areas.Based on diameters of 2.42 to 5.09μm,most HPB in the composting areas were expected to be deposited on the bronchus and secondary bronchus.However,in the packaging areas,the deposition of HPB(diameters 3.70 to 8.96μm)occurred in the upper part of the respiratory tract.Our results on the size distribution,abundance,and diversity of these bacteria offer important information for the systematic evaluation of bacterial pathogenicity and the potential health impacts on workers in composting plants and the surrounding residents.

关键词： size distribution Airborne bacteria Biological diversity Human pathogenic bacteria Composting plants

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Statistical Description of Debris Particle size distribution in Electrical Discharge Machining

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 67-72页

作者： JIA Zhenyuan ZHENG Xinyi WANG Fuji LIU Wei Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education Dalian University of Technology Dalian 116023 China

Gap debris as discharge product is closely related to machining process in electrical discharge machining（EDM）. A lot of recent researches have focused on the relationship among debris size, surfaces texture, remove rate, and machining stability. The study on statistical distribution of debris size contributes to the research, but it is still superficial currently. In order to obtain the distribution law of the debris particle size, laser particle size analyzer（LPSA） combined with scanning electron microscope（SEM） is used to analyze the EDM debris size. Firstly, the heating dried method is applied to obtain the debris particles. Secondly, the measuring range of LPSA is determined as 0.5–100 μm by SEM observation, and the frequency distribution histogram and the cumulative frequency distribution scattergram of debris size are obtained by using LPSA. Thirdly, according to the distribution characteristic of the frequency distribution histogram, the statistical distribution functions of lognormal, exponentially modified Gaussian（EMG）, Gamma and Weibull are chosen to achieve curve fitting of the histogram. At last, the distribute law of the debris size is obtained by fitting results. Experiments with different discharge parameters are carried out on an EDM machine designed by the authors themselves, and the machining conditions are tool electrode of red-copper material, workpiece of ANSI 1045 material and working fluid of de-ionized water. The experimental results indicate that the debris sizes of all experiment sample truly obey the Weibull distribution. The obtained distribution law is significantly important for all the models established based on the debris particle size.

关键词： electrical discharge machining debris particle measurement size distribution curve fitting

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Application of multi-phase particle swarm optimization technique to retrieve the particle size distribution

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Chinese Optics Letters 2008年第5期6卷 346-349页

作者：齐宏阮立明王圣刚史萌赵辉 School of Energy Science and Engineering Harbin Institute of Technology

The multi-phase particle swarm optimization （MPPSO） technique is applied to retrieve the particle size distribution （PSD） under dependent model. Based on the Mie theory and the Lambert-Beer theory, three PSDs, i.e., the Rosin-Rammer （R-R） distribution, the normal distribution, and the logarithmic normal distribution, are estimated by MPPSO algorithm. The results confirm the potential of the proposed approach and show its effectiveness. It may provide a new technique to improve the accuracy and reliability of the PSD inverse calculation.

关键词： Beverages Grain size and shape Optimization Particle size Particle size analysis Power spectral density Pulse shaping circuits size distribution

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Information Measure for size distribution of Avalanches in the Bak—Sneppen Evolution Model

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Chinese Physics Letters 2003年第1期20卷 31-34页

作者：李炜蔡勖 InstituteofParticlePhysics HuazhongNormalUniversityWuhau430079 SantaFeInstitute 1399HydeParkRoadSantaFeNM87501USA InstituteofParticlePhysics HuazhongNormalUniversityWuhau430

Information of avalanche size distribution is measured by calculating information entropy (IE) in the Bak-Sneppen evolution model. It is found that the IE increases as the model evolves. Specifically, we establish the relation between the IE and the self-organized threshold fc. The variation of the IE near the critical point yields an exponent entropy index E = (τ-1)/σ, where τ and σ represent the critical exponents for avalanche size distribution and avalanche size cutoff, respectively. A new quantity Dτ(g) (g = 1-(fc-G)(τ-1)/σ, where G is the gap of the current state), defined as 1-Iτ(g)/Iτ(1), with Iτ(g) and Iτ(1) being the IE for the current state and the critical one respectively, is suggested that it represents the distance between the state with gap G and the critical one.

关键词： size distribution

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