[Ambient VOCs Characteristics and Reactivity During O3 Pollution in Autumn in Urban Beijing].

In order to understand the effect of volatile organic compounds (VOCs) on ozone pollution, the concentrations, chemical composition variations, and ozone formation potential (OFP) were studied under different O3 concentrations, using high-resolution online monitoring data obtained in the urban site of Beijing in autumn of 2019. The results showed that the average concentration of VOCs was (22.22±10.10)×10-9, with the largest contribution of VOCs from alkanes (55.65%), followed by that of oxygenated volatile organic compounds (OVOCs) (16.23%) and alkenes (8.13%). Three ozone pollution episodes were captured during the observation period. The average concentration of VOCs on pollution days was (26.22±12.52)×10-9, which was 60.17%higher than that on clear days (16.37±7.19)×10-9. The value of ozone formation potential (OFP) on pollution days was 113.63 µg·m-3, which was 56.55%higher than that on clear days. The contributions of OVOCs and aromatics to OFP on pollution days increased by 6.51%and 1.55%, respectively, whereas that of alkenes declined (8.72%). The ratios of toluene to benzene (T/B) and benzene, toluene, and ethylbenzene (B:T:E) were 1.55 and 0.36:0.55:0.09, respectively, indicating that vehicle exhaust had significant effects on VOCs in autumn in urban Beijing. The back-trajectory results indicated a high contribution of southern air masses to atmospheric VOCs variations in autumn in urban Beijing.

High expression of MAGE-A9 contributes to stemness and malignancy of human hepatocellular carcinoma.

MAGE-A9, a well-characterized cancer testis antigen (CTA), belongs to a member of melanoma antigen gene (MAGE) family. In human malignancies, aberrant expression of MAGE genes correlated with poor clinical prognosis, increased tumor growth, metastases, and enrichment in stem cell populations of certain cancers. Cancer stem cells (CSCs) have been proposed to contribute to the major malignant phenotypes of liver cancer, including recurrence, metastasis and chemoresistance. However, expression and potential role of MAGE-A9 in liver cancer stem cells (LCSCs) still remain unclear. In the present study, we first analyzed the expression profiling of MAGE family genes in EpCAM+ and EpCAM- human hepatocellular carcinoma (HCC), based on public Gene Expression Omnibus (GEO) database. Among these examined MAGE members, MAGE-A9 is the only one with significantly higher expression in EpCAM+ HCC specimens as compared with EpCAM- HCC. Quantitative PCR analysis further confirmed that MAGE-A9 expression significantly elevated in a subtype of HCC patients that had features of hepatic stem/progenitor cells with high-level expression of EpCAM and α-fetoprotein (AFP). Moreover, MAGE-A9 displayed remarkably enriched expression in EpCAM+ HCC cells that were sorted by fluorescence-activated cell sorting and cultured HCC cell spheroids with characteristics of stem/progenitor cells. Functional experiments further revealed that MAGE-A9 overexpression promoted cell proliferation, colony formation, migration, chemoresistance, and tumorigenicity in the context of EpCAM+ HCC cells, whereas MAGE-A9 knockdown significantly inhibited anchorage-dependent and spheroid colony formation and in vivo tumorigenicity. Collectively, these data demonstrate that MAGE-A9 functions as an important regulator of LCSCs, and MAGE-A9 may serve as a potential therapeutic target against HCC stem/progenitor cells.

[Fugitive Dust Emission Characteristics from Building Construction Sites of Beijing].

Particulate matter (PM) is the primary air pollutant in Beijing, and its emission control is an important direction of air pollution prevention and control. Construction dust plays a significant role in the source of airborne particulate matter in Beijing. Due to population growth and economic development, the demand for residential and office space has been increasing which results in a high construction area in Beijing and dust pollution caused by construction activities. However, there are few studies focusing on fugitive dust emissions from construction sites and their contribution to air pollution in Beijing. Under this background, this paper established an estimation model of dust emission from construction sites, and used the localized emission factor to calculate the dust emission from 2000 to 2015 in Beijing, identified the emission characteristics and laws of construction dust emission and quantified the uncertainty range of the emissions. The WRF/CMAQ model system was used to simulate the contribution of dust pollution to quantify its influence on air quality. The results showed that the dust emission from construction sites in Beijing has been increasing, but the construction area is falling in recent years. However, the emission of PM is still high and needs to be paid enough attention. In the spatial distribution, the dust emissions in summer and autumn are larger than those in other seasons. As for spatial distribution, the construction dust is mainly concentrated in the urban function extension area and suburban area, which is related to the extension of population activities and the gradual development of urbanization. The contribution of construction dust to PM10 and PM2.5 concentration in the ambient air can reach 31.3 µg·m-3 and 9.6 µg·m-3, respectively. Through scenarios analysis, for further reduction of the emission from construction sites in 2030, more stricter standard for green construction and powerful supervision are needed.

[Exploring the Severe Haze in Beijing During December, 2015: Pollution Process and Emissions Variation].

Severe haze episodes shrouded Beijing and its surrounding regions again during December, 2015, causing major environmental and health problems. Beijing authorities had launched two red alerts for atmospheric heavy pollution in this period, adopted a series of emergency control measures to reduce the emissions from major pollution sources. To better understand the pollution process and emissions variation during these extreme pollution events, we performed a model-assisted analysis of the hourly observation data of PM2.5, and meteorological parameters combined with the emissions variation of pollution sources. The synthetic analysis indicated that: (1) Compared with the same period of last year, the emissions of atmospheric pollution sources decreased in December 2015. However, the emission levels of primary pollutants were still rather high, which were the main intrinsic causes for haze episodes, and the unfavorable diffusion conditions represented the important external factor. High source emissions and meteorological factors together led to this heavy air pollution process. (2) Emergency control measures taken by the red alert for heavy air pollution could decrease the pollutants emission by about 36% and the PM2.5 concentrations by 11% to 21%. Though the implementation of red alert could not reverse the evolution trend of heavier pollution, it indeed played an active role in mitigation of PM2.5 pollution aggravating. (3) Under the heavy pollution weather conditions, air pollutants continued to accumulate in the atmosphere, and the maximum effect by taking emergency measures occurred 48-72 hours after starting the implementation; therefore, the best time for executing emergency measures should be 36-48 hours before the rapid rise of PM2.5 concentration, which requires a more powerful demand on the accuracy of air quality forecast.

Conferring Natural-Derived Porous Microspheres with Surface Multifunctionality through Facile Coordination-Enabled Self-Assembly Process.

In this study, multifunctional chitin microspheres are synthesized and utilized as a platform for multiple potential applications in enzyme immobilization, catalytic reduction and adsorption. Porous chitin microspheres with an average diameter of 111.5 µm and a porous architecture are fabricated through a thermally induced phase separation method. Then, the porous chitin microspheres are conferred with surface multifunctionality through facile coordination-enabled self-assembly of tannic acid (TA) and titanium (Ti(IV)) bis(ammonium lactate)dihydroxide (Ti-BALDH). The multipoint hydrogen bonds between TA and chitin microspheres confer the TA-Ti(IV) coating with high adhesion capability to adhere firmly to the surface of the chitin microspheres. In view of the biocompatibility, porosity and surface activity, the multifunctional chitin microspheres are used as carriers for enzyme immobilization. The enzyme-conjugated multifunctional porous microspheres exhibit high catalytic performance (102.8 U·mg(-1) yeast alcohol dehydrogenase). Besides, the multifunctional chitin microspheres also find potential applications in the catalytic reduction (e.g., reduction of silver ions to silver nanoparticles) and efficient adsorption of heavy metal ions (e.g., Pb(2+)) taking advantages of their porosity, reducing capability and chelation property.

[Regional Source Apportionment of PM2.5 in Beijing in January 2013].

In January 2013, Beijing area experienced several severe haze weather events. The pollution of fine particles has become an important problem in Beijing. Understanding the sources of PM2.5 in Beijing is essential for solutions and related policy-formulations. Three-dimensional air quality modelling system was established to analyze the PM2.5 pollution during 20-24 January in 2013. PSAT technology was used to study the regional sources of Beijing PM2.5 pollution. The results showed that local emission was the major source of PM2.5 in Beijing City, with an average contribution rate of 34% . The average contribution rates of Hebei and Tianjin were 26% and 4%, respectively. The neighboring area and the boundary conditions contributed 12% and 24% to PM2.5 in Beijing. In the heavy pollution period, the influence of regional transportation increased significantly, and became the major source of PM2.5 pollution in Beijing. Nitrate in PM2.5 in Beijing mainly came from the surrounding area of Beijing City, while sulfate and secondary organic aerosols showed characteristics of long-distance transportation. Ammonium salt and other components were mainly from Beijing local contribution.

[Formation Mechanism of a Serious Pollution Event in January 2013 in Beijing].

The weather conditions, atmospheric environmental background and formation mechanism of a heavy air pollution episode in Beijing City from January 9th to 15th, 2013 was preliminarily investigated by combining observed data and the WRF meteorology model. The results showed that the average concentration of PM2.5 was 323 µg x m(-3) from January 10th to 14th; the heavy pollution episode was closely related to the local meteorological conditions; the stable atmospheric circulation pattern provided favorable environmental field for the lasting of this heavy air pollution; small wind speed, high humidity, low PBL, and lasting temperature inversion were the main reasons for this heavy air pollution incident; further analysis showed that contributions of regional transmission to the receptor sites in Beijing were between 53% - 69% and there were obvious secondary conversions and transformations; overall regional transportation played a more important role during this serious air pollution incident; the meteorological conditions played a key role in the formation and destruction of the heavy air pollution, therefore we need to strengthen the study on early warning of heavy air pollution, in order to prevent and control the air heavy pollution effectively.