[Analysis of the Jumping Characteristics and Influencing Factors of Ozone Pollution in Beijing].

Based on environmental monitoring data and meteorological observation data from 2016 to 2022 in Beijing, combined with backward trajectory clustering and potential source area contribution analysis, the characteristics, meteorological impacts, and potential source areas of ozone (O3) pollution were analyzed. The results showed that there was a total of 41 O3 pollution processes with jumping characteristics in Beijing from 2016 to 2022, with an average of 5.9 times a year. The occurrence time was concentrated in May to July, and the day of the jump (OJD2) was higher than the day before the jump (OJD1). The average value of ρ(O3-8h) was 78.3% higher, and the peak concentration was 78.9% higher. The high O3 concentration zone in the OJD2 region exhibited a characteristic of advancing from south to north. The main reasons for the occurrence of jumped O3 pollution in Beijing could be summarized as local accumulation caused by unfavorable meteorological conditions and regional transmission impact. The occurrence of jump-type ozone pollution was characterized by an increase in southerly wind frequency, temperature rise, pressure decrease, and precipitation decrease. The increase in southerly wind frequency provided conditions for the transport of O3 and its precursors, and rapid photochemical reactions occurred under local high temperatures, with less superimposed precipitation, comprehensively pushing up the ozone concentration level of OJD2. Six air mass transporting pathways were identified through clustering analysis; the air mass from the direction north of OJD2 decreased by 11.2%, whereas the air mass from the south and east directions increased by 6.7% and 4.4%, respectively, with the air masses mainly transmitting over short distances. The ozone concentration corresponding to the south and east directions was relatively high, making a significant contribution to Beijing's pollution. The analysis of potential source areas revealed that the main potential source areas of OJD2 ozone pollution were the central, southern, and eastern parts of Beijing-Tianjin-Hebei, which contributed 82.6% to the pollution trajectory. There was a significant contribution of regional transport during jump-type ozone pollution, and it is necessary to strengthen joint prevention and control in the Beijing-Tianjin-Hebei Region.

Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach.

A simple thermal-mechanical model for friction stir spot welding (FSSW) was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design.

[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.

Conditionally replicative adenovirus vector carrying TRAIL gene for enhanced oncolysis of human hepatocellular carcinoma.

Conditionally replicative adenovirus (CRAd) mediated tumor specific gene therapy based on transcriptional control is considered a new direction for the treatment of cancer. Our previous studies showed that an HS4 insulator increased the alpha-fetoprotein (AFP) promoter-driven expression in the context of an adenovirus (Ad) vector, while retaining the highly specific gene expression in hepatoma cells in vitro and in vivo. In this study, we constructed two HS4-AFP promoter based CRAd vectors (Ad.HS4.AFP.E1a/TRAIL and Ad.HS4.AFP.E1a) with and without the expression cassette of TNF-related apoptosis-inducing ligand (TRAIL). The TRAIL-expressing virus vector, Ad.HS4.AFP.E1a/TRAIL, exhibited more obvious oncolytic effect than Ad.HS4.AFP.E1a in both high-AFP-producing HCC cell lines (Hep3B and HUH7) and a low-AFP-producing HCC cell line (PLC/PRF/5) examined, indicating endogenous TRAIL over-expression increased CRAd potency. The enhanced hepatoma cell death was mainly mediated through apoptotic mechanism, as evidenced by the activation of caspase-3, binding of annexin V and inhibition by caspase inhibitor z-vad-fmk. In s.c. xenograft of low-AFP-producing PLC/PRF/5 hepatoma model, the administration of Ad.HS4.AFP.E1a/TRAIL resulted in a more potent oncolytic effect compared with the same dose of Ad.HS4.AFP.E1a 28 days after virus exposure. This study demonstrated that the TRAIL in the context of a CRAd vector was able to increase the oncolytic activity in low-AFP-producing HCC cells in vitro and in vivo. Considering that oncolytic viruses destroy tumor cells expressing low levels of the tumor marker is a clinical concern, TRAIL might be a useful tool to improve the efficacy of these vectors.