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Chinese Chemical Letters 2024年第4期35卷 193-198页

作者： Tingting Liu Pengfei Sun Wei Zhao Yingshuang Li Lujun Cheng Jiahai Fan xiaohui bi Xiaoping Dong College of Chemistry and Chemical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China College of Environmental Science and Engineering Nankai UniversityTianjin 300071China Hangzhou Kaiming Catalyst Co. Ltd.Hangzhou 310013China

Mg-doped manganese oxide octahedral molecular sieve(Mg-OMS-2)catalysts were prepared by hydrothermal method.The photothermal degradation performance of these catalysts for formaldehyde(HCHO)in batch system and continuous system was investigated.The light absorption of OMS-2 was increased by Mg-doped,especially for near infrared light,which promoted surface temperature reach a maximum of 214.8℃ under xenon irradiation.At this temperature,the reinforced surface lattice oxygen and oxygen vacancy that formed by lattice distortion via Mg-doped were activated.The best HCHO elimination efficiency was achieved over Mg_(0.2)/OMS-2 catalyst with Mg^(2+)/Mn^(2+)=1/5,which could reduce HCHO from 250 ppm to 10 ppm within 20 min.The in situ DRIFTS was also carried out to monitor the changes in the content of reaction intermediates and analyze the degradation paths of HCHO.It was found the HCHO was attacked by formed·OH and·O^(2-) to generate formate species and carbonate species,and finally transformed to CO_(2) and H_(2)O.This photothermal catalytic oxidation process exhibited a high efficiency purification of HCHO without the help of extra energy consumption.

关键词： Mg doping Photothermal catalysis OMS-2 HCHO Reaction mechanism

Quantifying the impacts of emissions and meteorology on the interannual variations of air pollutants in major Chinese cities from 2015 to 2021

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Science China Earth Sciences 2023年第8期66卷 1725-1737页

作者： Qili DAI Tianjiao DAI Linlu HOU Linxuan LI xiaohui bi Yufen ZHANG Yinchang FENG State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control College of Environmental Science and EngineeringNankai UniversityTianjin 300350China China Meteorological Administration-Nankai University Cooperative Laboratory for Atmospheric Environment-Health Research Tianjin 300350China

Air pollutant concentration is a function of emission rates and meteorology.To accurately evaluate the effect of control measures,the meteorological covariate must be corrected from the observations.This study quantified the impacts of emission abatement and meteorological condition on the interannual variations of SO_(2),NO_(2),CO,O_(3),PM_(10) and PM_(2.5) concentrations in 31 major Chinese cities using an optimized machine learning-based meteorological normalization technique.Overall,the annual average concentrations of SO_(2),NO_(2),CO,PM_(10)and PM_(2.5)were reduced by 86%,51%,99%,86% and 88%from 2015 to 2020,respectively,in the studied cities,attributable to their emission reductions.However,the concentration of O_(3) was found with no significant decrease with the reduction of precursors.Emission abatement notably improved air quality between 2015 and 2018.Such a decline in emissions tended to progressively slow down since 2018.Overall,the meteorological conditions in 2016–2017 and 2018–2019 were unfavorable for a better air quality,while it became favorable in 2020–2021.Specifically,emission abatement in 2021 further lowered the concentrations of SO_(2),NO_(2),CO,and PM_(2.5),while the emission of PM_(10) increased.And changes in precursors emissions worsened O_(3) air quality.To meet the demand of improving air quality,more aggressive abatement measures need to be formulated to synergistically reduce NOx,volatile organic compounds,and coarse particles.

关键词： Air pollution Air quality Machine learning Meteorology Emissions Policy evaluation

Size distribution and chemical characteristics of particles from crop residue open burning in North China

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Journal of Environmental Sciences 2021年第11期33卷 66-76页

作者： Tingkun Li Qili Dai xiaohui bi Jianhui Wu Yufen Zhang Yinchang Feng State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control College of Environmental Science and EngineeringNankai UniversityTianjin300350China.

Crop residue open burning is an important emission source of ambient particles in China.This study analyzed the particle emission characteristics of crop residue open burning through combustion experiments with a novel open combustion simulation device using three typical crop straws in north China(corn,wheat,and rice).Particle samples size ranging from 0.006–9.890μm were collected by an Electrical Low Pressure Impactor plus,a high size-resolution instrument capable of dividing particles into 14 size stages.The size distributions of organic carbon(OC),elemental carbon(EC),water-soluble ions,and elements were analyzed,and source chemical profiles were constructed for PM0.1,PM1,PM2.5,and PM10.The number concentration of particles was concentrated in the Aiken nuclei mode(0.006–0.054μm),accounting for 75%of the total number,whereas the mass concentration was concentrated in the accumulation mode(0.054–0.949μm),accounting for 85.43%of the mass loading.OC,EC,Cl−,and K(include total K and water-soluble K)were the major chemical components of the particles,whose mass percentage distributions differed from those of other components.These fivemain components exhibited a bell-shaped size distribution in the 0.006–9.890μm range,whereas the other components exhibited a U-shaped distribution.Among the chemical profiles for PM0.1–PM10,OC was the most important component at 10–30%,followed by EC at 2%–8%.The proportions of K^(+),Cl^(−),and K varied substantially in different experimental groups,ranging from 0–15%,and K+and Cl−were significantly correlated(r=0.878,α=0.000).

关键词： Crop residue Open burning Size distribution Source profile Electrical Low Pressure Impactor plus(ELPI+)

Assessment of heavy metal pollution characteristics and human health risk of exposure to ambient PM_(2.5) in Tianjin,China

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Particuology 2015年第3期13卷 104-109页

作者： Peifei Chen xiaohui bi Jiaqi Zhang Jianhui Wu Yinchang Feng College of Environmental Science and Safety Engineering Tianjin University of Technology College of Environmental Science and Engineering Nankai University

To examine the features of heavy metal pollution of PM2.5 （particulate matter less than 2.5 μm） in Tianjin, China, as well as the exposure risk of PM2.5 to human health, we analyzed ambient PM2.5samples collected from a campus of Nankai University in June, August, and October 2012. The concentrations of PM2.5 and heavy metals （Ni, Cu, Pb, Zn, Cr, Cd, Hg, As and Mn） in PM2.5 were analyzed by gravimetric analysis and inductively coupled plasma-mass spectrometry, respectively. The results show that the heavy metals contained in PM2.5 were, in descending order, Cu, Zn, Pb, Mn, Cr, Ni, Cd, As, and Hg. The proportion of Cd exceeded the secondary level of National Ambient Air Quality Standard of China （GB 3095-2012） by 1.3 times, while others were within the limit. Enrichment factor analysis indicated that Cu, Zn, Cd, Pb, and Hg are mainly from anthropogenic sources. Principal component analysis indicated that the main sources of the heavy metals are vehicle exhaust, chemical waste, and coal-burning activities. The nine heavy metals which may cause health issues by exposure through the human respiratory system and should be further examined are Cr, Cd, As, Ni, Cu, Pb, Mn, Zn, and Hg, in the order of decreasing risk levels. With reference to the U.S. EPA standard the risk levels of all nine metals were below the acceptable level （10 6/year）.

关键词： PM2.5 Heavy metalEnrichment factorPrincipal component analysisHealth risk assessment

Insight into the critical factors determining the particle number concentrations during summer at a megacity in China

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Journal of Environmental Sciences 2019年第1期31卷 169-180页

作者： Baoshuang Liu xiaohui bi Jiaying Zhang Jie Yuan Zhimei Xiao Qili Dai Yinchang Feng Yufen Zhang State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control & Center for Urban Transport Emission Research College of Environmental Science and EngineeringNankai University Tianjin Environmental Monitoring Center

To identify the critical factors impacting the number concentration of particles with the aerodynamic diameters less than 2.5 μm(PNC_(2.5)), the continuous measurement of PNC_(2.5),chemical components in PM_(2.5), gaseous pollutants and meteorological conditions were conducted at an urban site in Tianjin in June 2015. Results indicated that the average PNC_(2.5) was 2839 ± 2430 d N/dlog Dp 1/cm^3 during the campaign. Compared to other meteorological parameters, the relative humidity(RH) had the strongest relationship with PNC_(2.5), with a Pearson's correlation coefficient of 0.53, and RH larger than 30% influenced strongly PNC_(2.5).The important influence of secondary reactions on PNC_(2.5) was inferred due to higher correlation coefficients between PNC_(2.5) and SO_4^(2-), NO_3^-, NH_4^+(r = 0.78–0.89; p < 0.01) and between PNC_(2.5) and ratios that represent the conversion of nitrogen and sulfur oxides to particulate matter(r = 0.42–0.49; p < 0.01). Under specific RH conditions, there were even stronger correlations between PNC_(2.5) and NO_3^-, SO_4^(2-), NH_4^+, while those between PNC_(2.5) and EC, OC were relatively weak, especially when RH exceeded 50%. Principal component analysis(PCA) and Pearson's correlation analysis indicated that secondary sources, vehicle emission and coal combustion might be major contributors to PNC_(2.5). Backward trajectory and potential source contribution function(PSCF) analysis suggested that the transport of air masses originated from these regions around Tianjin(Liaoning, Hebei, Shandong and Jiangsu) influenced critically PNC_(2.5). The north of Jiangsu, the west of Shandong, and the east of Hebei were distinguished as major potential source-areas of PNC_(2.5) by PSCF model.

关键词： Particle number concentration Correlation analysis Emission sources PSCF

Roles of histones and nucleosomes in gene transcription

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Chinese Science Bulletin 2001年第3期46卷 184-188页

作者： Baiqu Huang Qinhua Zeng xiaohui bi Yuhong Wang Yuxin Li NE Normal Univ Inst Cytol & Genet Changchun 130024 Peoples R China

This article reviews the latest research developments in the field of eukaryotic gene regulation by the structural alterations of chromatin and nucleosomes. The following issues are briefly addressed: (i) nucleosome and histone modifications by both the ATP-dependent remodeling complexes and the histone acetyltransferases and their roles in gene activation; (ii) competitive binding of histones and transcription factors on gene promoters, and transcription repression by nucleosomes; and (iii) influences of linker histone HI on gene regulation. Meanwhile, the significance and impact of these new research progresses, as well as issues worthwhile for further study are commented.

关键词： histones nucleosome chromatin remodeling gene transcription.

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无人车目标识别主干网络技术特点对比分析

兵工自动化 2024年第1期43卷 78-87页

作者：樊胜利张玉芝毕晓慧河北工业职业技术大学汽车工程系石家庄050019

目标识别是无人车自动驾驶视觉感知模块的核心技术之一。当前,目标识别主要依靠主干网络提取特征,进而对目标进行分类与回归。通常情况下,无人车嵌入式计算平台的计算与存储能力有限,为了降低主干网络的算力与存储量,提升无人车的计算... 详细信息

目标识别是无人车自动驾驶视觉感知模块的核心技术之一。当前,目标识别主要依靠主干网络提取特征,进而对目标进行分类与回归。通常情况下,无人车嵌入式计算平台的计算与存储能力有限,为了降低主干网络的算力与存储量,提升无人车的计算速度与效率,对目标分类任务的主干网络进行综合比较分析。围绕卷积核、感受野、池化层、全连接层、激活函数等,以cifar10和cifar100为实验数据,从理论分析与数据实践层面,对主干网络算子的选择与网络搭建进行分析对比,总结、归纳特征提取主干网络搭建的主要思路与做法。结果表明,该分析结论对目标分类主干网络在嵌入式无人车系统中的应用具有一定的理论指导与参考价值。

关键词：无人车目标检测与分类人工智能卷积神经网络

Source apportionment of ambient PM_(10) in urban areas of Wuxi,China

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Frontiers of Environmental Science & Engineering 2011年第4期5卷 552-563页

作者： Bo HAN xiaohui bi Yonghua XUE Jianhui WU Tan ZHU Baogui ZHANG Jianqing DING Yuanxin DU College of Environmental Science and Engineering Nankai UniversityTianjin 300071China Wuxi Environmental Monitoring Center Jiangsu 214023China

A total of 168 PM_(10)samples were collected during the year of 2005 at eight sites in the city of Wuxi in China.Fifteen chemical elements,three water-soluble ions,total carbon and organic carbon were analyzed.Six source categories were identified and their contributions to ambient PM_(10)in Wuxi were estimated using a nested chemical mass balance method that reduces the effects of colinearity on the chemical mass balance model.In addition,the concentrations of secondary aerosols,such as secondary organic carbon,sulfate and nitrate,were quantified.The spatially averaged PM_(10)was high in the spring and winter(123μg·m^(-3)and low in the summer-fall(90μg·m^(-3)).According to the result of source apportionment,resuspended dust was the largest contributor to ambient PM_(10),accounting for more than 50%of the PM_(10)mass.Coal combustion(14.6%)and vehicle exhaust(9.4%)were also significant source categories of ambient PM_(10).Construction and cement dust,sulfates,secondary organic carbon,and nitrates made contributions ranging between 4.1%and 4.9%.Other source categories such as steel manufacturing dust and soil dust made low contributions to ambient PM_(10).

关键词： source apportionment inhalable particulate matter nested chemical mass balance method

User Grouping and Scheduling for Joint Spatial Division and Multiplexing in FDD Massive MIMO System

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International Journal of Communications, Network and System Sciences 2017年第8期10卷 176-185页

作者： Gang Wang Jianing Zhao xiaohui bi Yuting Lu Fuyu Hou National Mobile Communications Research Laboratory Southeast University Nanjing China

Massive multiple-input multiple-output (MIMO) is a key technology for the 5th Generation wireless communication systems. Joint spatial division and multiplexing (JSDM) method can reduce the cost of downlink training and feedback for CSIT of frequency-division duplexing (FDD) system. In this paper, we studied user grouping and user scheduling problems based on JSDM, and proposed an improved greedy user scheduling algorithm with lower complexity. Numerical results show that the user grouping and scheduling based on the proposed improved algorithm have much lower computational complexity while resulting in only a slight loss in system performance.

关键词： Massive MIMO FDD JSDM User Scheduling

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富硒乳酸菌的制备

食品工业 2024年第3期45卷 53-56页

作者：陈丹曹亚莉刘文雅苗梦雅毕小惠王烁骞商丘市产品质量检验检测研究中心商丘476000

课题以嗜酸乳杆菌(Lactobacillus acidophilus)、动物双歧杆菌(bifidobacterium animals)、植物乳杆菌(Lactobacillus plantarum)、嗜热链球菌(Streptococcus thermopiles)作为供试菌株,进行富硒发酵试验,测定菌株的富硒能力及确定其适宜硒浓度。采用单因素试验和正交试验优化了益生菌的培养基组成。采用响应面法研究了富硒益生菌的发酵工艺,获得了富硒菌粉。结果显示:(1)在选购的4种乳酸菌中,嗜酸乳杆菌的富硒能力最强,且硒添加量为0~1 000 mg/kg时,嗜酸乳杆菌冻干粉的活菌数均能达到千亿级(即1×1012);优化的益生菌的培养基配方为蔗糖5%、蛋白胨与酵母膏的总添加量0.35%、蛋白胨-酵母膏比例3∶2、K2HPO4的总添加量0.1%;(2)优化嗜酸乳杆菌的最佳富硒工艺,并进行验证试验:菌种硒含量为2 902.81 mg/kg,加硒量为15.30 mg/kg,加硒时间为6.64 h。在此条件下,富硒益生菌产品得率为498.46 mg/kg,硒含量为13 039.62 mg/kg。

关键词：富硒益生菌嗜酸乳杆菌生物转化