Water-soluble brown carbon in atmospheric aerosols from the resource-dependent cities: Optical properties, chemical compositions and sources.

As a vital type of light-absorbing aerosol, brown carbon (BrC) presents inherent associations with atmospheric photochemistry and climate change. However, the understanding of the chemical and optical properties of BrC is limited, especially in some resource-dependent cities with long heating periods in northwest China. This study showed that the annual average abundances of Water-soluble BrC (WS-BrC) were 9.33±7.42 and 8.69±6.29 µg/m3 in Baotou and Wuhai and the concentrations, absorption coefficient (Abs365), and mass absorption efficiency (MAE365) of WS-BrC presented significant seasonal patterns, with high values in the heating season and low values in the non-heating season; while showing opposite seasonal trends for the Absorption Ångström exponent (AAE300-400). Comparatively, the levels of WS-BrC in developing regions (such as cities in Asia) were higher than those in developed regions (such as cities in Europe and Australia), indicating the significant differences in energy consumption in these regions. By combining fluorescence excitation-emission matrix (EEM) spectra with the parallel factor (PARAFAC) model, humic-like (C1 and C2) and protein-like (C3) substances were identified, and accounted for 61.40%±4.66% and 38.6%±3.78% at Baotou, and 60.33%±6.29% and 39.67%±4.17% at Wuhai, respectively. The results of source apportionment suggested that the potential source regions of WS-BrC varied in heating vs. non-heating seasons and that the properties of WS-BrC significantly depended on primary emissions (e.g., combustion emissions) and secondary formation.

Changes in stoichiometric characteristics of ambient air pollutants pre-to post-COVID-19 in China.

To prevent the Corona Virus Disease 2019 (COVID-19) spreading, Chinese government takes a series of corresponding measures to restrict human mobility, including transportation lock-down and industries suspension, which significantly influenced the ambient air quality and provided vary rare time windows to assess the impacts of anthropological activities on air pollution. In this work, we divided the studied timeframe (2019/12/24-2020/2/24) into four periods and selected 88 cities from 31 representative urban agglomerations. The indicators of PM2.5/PM10 and NO2/SO2 were applied, for the first time, to analyze the changes in stoichiometric characteristics of ambient air pollutants pre-to post-COVID-19 in China. The results indicated that the ratios of NO2/SO2 presented a responding decline, especially in YRD (-5.01), YH (-3.87), and MYR (-3.84), with the sharp reduction of traffic in post-COVID-19 periods (P3-P4: 2.34 ± 0.94 m/m) comparing with pre-COVID-19 periods (P1-P2: 4.49 ± 2.03 m/m). Whereas the ratios of PM2.5/PM10 increased in P1-P3, then decreased in P4 with relatively higher levels (>0.5) in almost all urban agglomerations. Furthermore, NO2 presented a stronger association with PM2.5/PM10 variation than CO; and PM2.5 with NO2/SO2 variation than PM10. In summary, the economic structure, lockdown measures and meteorological conditions could explain the noteworthy variations in different urban agglomerations. These results would be in great help for improving air quality in the post-epidemic periods.

Stoichiometric characteristics and economic implications of water-soluble ions in PM2.5 from a resource-dependent city.

The stoichiometric characteristics of water-soluble ions (WSIs) in PM2.5, which can be used as an indicator socioeconomic development level, are mostly depending on the sources and formation mechanism of PM2.5. This work presents the stoichiometric characteristics and socioeconomic linkage of WSIs in PM2.5 from a resource-dependent city. The relationship between NO3-/SO42- and car parc indexes the contribution of mobile emission source. The equivalent ratio of WSIs suggested that aerosol particles were weak acidic due to the deficiency of cations in PM2.5, which was consistent with the average annual pH (6.27) of precipitation in Wuhai in 2015. NH4+ neutralizes PM2.5 acidity in clean and polluted days, while Ca2+ and NH4+ in dust storm days. Furthermore, the PCA analysis indicated the multi-sources pollution characteristics from Spring to Fall, which was related the small build-up area (only 62.30 km2) and the close-set of various industrial enterprises in Wuhai. The ratios of NO2/SO2 may not work effectively to identify the importance of mobile versus stationary pollution emission sources when the heavy emission from the secondary industry, especially the proportion of secondary industry higher than 65% and the ratios of NO2/SO2 lower than 0.4. This work contributes to more effective control strategies for PM2.5 in resource-dependent areas.

Geochemical characteristics and socioeconomic associations of carbonaceous aerosols in coal-fueled cities with significant seasonal pollution pattern.

Carbonaceous aerosols, comprising organic carbon (OC) and elemental carbon (EC), are critical component of fine particulate matter (PM2.5), with diverse impacts on air quality and human health. This study investigated the concentrations and seasonal patterns of carbonaceous species in PM2.5 during both the heating season (January 2021) and non-heating season (July 2021) in three coal-fueled cities in northern China, as well as the differences in carbonaceous aerosols and their associations with socioeconomic parameters in cities situated on either side of the "Hu Line" in China. The results showed that, owing to intensified coal combustion and unfavorable meteorological conditions, levels of OC, EC, and OC/EC ratios were higher in winter compared to summer. Moreover, the presence of dust (DU) and light pollution (LP) days resulted in elevated OC levels but decreased EC levels. The Char-EC/Soot-EC ratios were highest during LP, followed by CL and DU. A source apportionment analysis demonstrated that coal burning, vehicle exhaust, road dust, and biomass burning were the primary contributors to carbonaceous aerosols, as confirmed by diagnostic ratios, Char-EC/Soot-EC ratios, and PCA analysis. Furthermore, our study found that carbonaceous aerosols concentrations and source apportionment primarily varied with diurnal and seasonal trends and different pollution types. Additionally, at the national scale, population density and urban green space exhibited a positive correlation with OC/EC ratios (p < 0.05), while energy consumption per unit of GDP showed a negative correlation (p < 0.05). The observation that OC/EC ratios were lower in coal-fueled cities than in economy-based cities suggests a more severe pollution scenario. These findings highlight the importance of comprehending of the seasonal variation and chemical characteristics of carbonaceous aerosol for understanding air pollution sources and characteristics, which is essential for both air quality management and human health.

Heating events drive the seasonal patterns of volatile organic compounds in a typical semi-arid city.

The emission characteristics, source apportionment and chemical behavior of volatile organic compounds (VOCs) are important for strategy-making on ozone (O3) and fine particulate matter (PM2.5) control. Based on the continuous observation during four seasons, the seasonal characteristics, chemical reactivity and source apportionment of 116 VOCs species were studied in a typical semi-arid city with no relevant research. The results showed that the annual average concentrations of total volatile organic compounds (TVOCs) in Hohhot was 44.67 ± 46.59 ppbv with the predominant of alkanes and oxygenated volatile organic compounds (OVOCs). The sharp increment of TVOCs were explained by the elevating OVOCs and alkanes in autumn, while alkanes and alkenes in winter. The levels of alkenes presented negative and positive correlations with solar radiation and PM10, respectively. The mixing ratios accounted for 30% (alkanes) and 23% (alkenes and aromatics) of the TVOCs, respectively; while their ozone formation potential (OFP) ~15% and nearly 50% (even 75% in winter), respectively, indicating that the OFP of different VOCs species depends not only on their concentrations but more importantly on their chemical activity in atmosphere. According to the seasonal source apportionment, both the high levels of short-chain alkanes, alkenes and aromatics and the increasing coal sales volume suggested that the combustion sources were the predominant in heating seasons, while solvent uses was extracted as the most predominant during non-heating seasons. In non-heating seasons, the biogenic emission sources, ranking as the second contributor, were significantly higher than heating seasons. Isoprene was the most active biogenic VOCs species, bagging test results showed that deciduous trees were the predominant contributors for isoprene (~99%), while coniferous trees and shrub for monoterpenes (>95%). It will be helpful for understanding the characteristics of VOCs in Chinese national key development areas and informing policy to control semi-arid regional VOCs air pollution.

[Immunogenicity of single-dose HBsAg-PLGA controlled release microspheres in mice].

AIM: To investigate the level of immune response and the immune mechanism of the single-dose hepatitis B surface antigen (HBsAg)-poly (d, l)-lactide-co-glicolide acid (PLGA) microspheres in BALB/c mice. METHODS: Three kind of HBsAg-PLGA microspheres, HBsAg-PLGA50/50-COOH microspheres, HBsAg-PLGA75/25 microspheres and HBsAg-PLGA50/50 microspheres, were prepared by double emulsion microencapsulation technique used three kinds of PLGA with different L/G ratio. The single-dose of HBsAg-PLGA microspheres was subcutaneously injected into BALB/c mice at the dose of 7.5 microg HBsAg per mouse. The conventional aluminum-adjuvant vaccine was subcutaneously injected at 0, 1 and 2 month as positive control. In certain time interval, the induced immune level of total antibody was detected by enzyme linked immunosorbent assay (ELISA). For subclass of IgG antibody and cytokines studies, the dose of HBsAg was 2.5 microg per mouse. RESULTS: The HBsAg-PLGA microspheres could successfully induce a humoral immune response in BALB/c mice. Compared with the conventional aluminum-adjuvant vaccine, the antibody response of the HBsAg-PLGA50/50-COOH microspheres was significantly lower than the group received three injections of aluminum-adjuvant vaccine (P < 0.01) except for a higher priming response during the early 6 weeks. The results were ascribed to the relatively rapid degradation charactics of PLGA50/50-COOH polymer. The immune response for the HBsAg-PLGA50/50 microspheres and HBsAg-PLGA75/25 microspheres were comparable to the group administered with aluminum-adjuvant vaccine (P > 0.05) which was due to the sustained degradation of PLGA50/50 and PLGA75/25 polymer. CONCLUSION: The HBsAg-PLGA microsphere is a promising candidate for the controlled delivery of a vaccine which does not require multiple injections.

Overcoming HBV immune tolerance to eliminate HBsAg-positive hepatocytes via pre-administration of GM-CSF as a novel adjuvant for a hepatitis B vaccine in HBV transgenic mice.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is known to be a potential vaccine adjuvant despite contradictory results from animal and human studies. The discrepancies may be due to the different doses and regimens of GM-CSF that were used, given that either mature or immature dendritic cells (DCs) could be induced under different conditions. To test the hypothesis that GM-CSF can be used as a novel adjuvant for a hepatitis B virus (HBV) therapeutic vaccine, we administered GM-CSF once per day for three days prior to vaccination with recombinant HBV vaccine (rHBVvac) in mice. We observed greater DC maturation in these pre-treated animals at day 3 as compared to day 1 or day 2 of daily GM-CSF administration. This strategy was further investigated for its ability to break the immune tolerance established in hepatitis B surface antigen-transgenic (HBsAg-Tg) animals. We found that the levels of induced anti-HBsAg antibodies were significantly higher in animals following three days of GM-CSF pre-treatment before rHBV vaccination after the third immunization. In addition to the increase in anti-HBsAg antibody levels, cell-mediated anti-HBsAg responses, including delayed-type hypersensitivity, T-cell proliferation, interferon-γ production, and cytotoxic T lymphocytes, were dramatically enhanced in the three-day GM-CSF pre-treated group. After adoptive transfers of CD8+ T cells from immunized animals, antigen-specific CD8+ T cells were observed in the livers of recipient HBsAg-Tg animals. Moreover, the three-day pre-treatments with GM-CSF prior to rHBVvac vaccination could significantly eliminate HBsAg-positive hepatocytes, suggesting beneficial therapeutic effects. Therefore, this protocol utilizing GM-CSF as an adjuvant in combination with the rHBVvac vaccine has the potential to become a novel immunotherapy for chronic hepatitis B patients.

[Preparation, release and immunogenicity evaluation of HBsAg-PLGA microspheres].

OBJECTIVE: To investigate microencapsulation technique, release of HBsAg-PLGA microspheres and degradation of the polymer in vitro, and the level of immune response after the single-dose HBsAg-PLGA microspheres subcutaneously injected (sc) to BALB/c mice. METHODS: HBsAg-PLGA microspheres were prepared by double emulsion microencapsulation technique with orthogonal experiments. The pharmaceutical characteristics of size and surface morphology, antigen loading efficiency, release of HBsAg-PLGA microspheres and degradation of the polymer in vitro, and the level of immune response after single sc of PLGA microspheres in BALB/c mice were investigated. RESULTS: The concentration of PVA was the significant factor affecting the particle size (P<0.05). The release of protein from the microspheres was controlled mainly by the bulk erosion of polymer matrix. When single sc of HBsAg-PLGA microspheres mixed with different formulations, the immunogenicity effect was comparable to that of the aluminium adjuvant vaccine. CONCLUSION: The single-dose HBsAg-PLGA microspheres mixture with different release behavior is a promising candidate for controlled delivery vaccine.

[Effect of strategy of control and prevention of intestinal nematodiasis in Dongtai City, Jiangsu Province].

OBJECTIVE: To explore the strategy of intestinal nematodiasis control in Dongtai City, Jiangsu Province. METHODS: The strategy of mass drug administration assisted with health education was applied in Dongtai City, which was a high endemic area of intestinal nematodiasis, and then the health education and promotion assisted with drug administration of focus population and other integrated control measures, such as the improvement of drinking water, lavatories, and environment, was applied to consolidate the achievement. RESULTS: The infection rate of intestinal nematodes reduced from 79.97% in 1989 to 6.30% in 1999, and the infection rates of hookworm, Ascaris lumgricoides and Trichuris trichura reduced to 3.31%, 0.60% and 2.57%, respectively, achieving the standard of intestinal nematodiasis control. In 2002, the infection rate of intestinal nematodes reduced to 3.73%, and the infection rates of hookworm, Ascaris lumgricoides and Trichuris trichura reduced to 2.46%, 0.20% and 1.08%, respectively, achieving the standard of effective intestinal nematodiasis control. The infection rate of intestinal nematodes was kept less than 1% after 2004. CONCLUSION: The integrated strategy of intestinal nematodiasis control in Dongtai City is effective and valuable for promotion in high endemic areas of intestinal nematodiasis.

[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province. II. Surveillance pattern and effect of Oncomelania hupensis snail status in Dongtai City, Jiangsu Province].

OBJECTIVE: To explore the method of Oncomelania hupensis snail surveillance in transmission-interrupted regions of schistosomiasis, so as to provide a new pattern for the surveillance of snail status in the transmission-interrupted areas. METHODS: In Dongtai County, north of Jiangsu Province where the transmission of schistosomiasis was interrupted, the surveillance of snail status was performed by means of the village-level general survey, village-level sampling survey, snail survey in key settings of township and county, and snail reporting by residents. In addition, quality-control snail sites were set up for quality control. The effectiveness and cost of the four methods of snail surveillance was compared. RESULTS: A total of 163 079 settings and 22 785.62 hm2 were surveyed in Dongtai County from 2008 to 2013, and 89 residual snail breeding sites were found, with a snail area of 1.48 hm2. The patterns of village-level general survey, village-level sampling survey, and snail survey in key settings of township and county were employed for investigation of 94 550, 45 033 and 23 496 settings, consisting of 57.98%, 27.61% and 14.41% of total settings, and 2, 0 and 6 settings were found with snails, with 0.021/thousand, 0, and 0.255/thousand detection rates of settings with snail breading sites, respectively. The pattern of snail survey in key settings of township and county was more effective than that of village-level survey to detect-snail breeding sites (χ2 = 19.158, P = 0). The recovery rate of quality-control snail breeding sites was 52.56%, 38.27% and 73.62% for the three patterns of snail survey, respectively, and the pattern of snail survey in key settings of township and county showed a higher quality for snail survey than that of village-level survey (χ2 = 111.597 and 85.991, both P = 0). During the period from 2008 to 2013, 289 person-times reported 279 suspected snail habitats and 1 501 living snails, and no Oncomelania snails were found. During the 6-year period, there were 1617.5, 964.7 and 527.7 thousand RMB invested for village-level general survey, village-level sampling survey, and snail survey in key settings of township and county, and the cost of snail survey per hm2 was 129.88, 133.6 and 162.57 RMB/hm2, respectively. The cost of village-level general survey and snail survey in key settings of township and county to detect a snail-breeding site was 808 800 and 88 000 RMB, respectively (t = 12.850, P = 0.000), and the cost of snail survey in key settings of township and county was 10.88% of that of village-level general survey. CONCLUSION: The snail survey in key settings of township and county is a highly effective and high-quality method for snail surveillance, which miay serve as a prior way for the surveillance of snail status in the transmission-interrupted areas of schistosomiasis.

A "GC-rich" method for mammalian gene expression: a dominant role of non-coding DNA GC content in regulation of mammalian gene expression.

High mammalian gene expression was obtained for more than twenty different proteins in different cell types by just a few laboratory scale stable gene transfections for each protein. The stable expression vectors were constructed by inserting a naturally-occurring 1.006 kb or a synthetic 0.733 kb DNA fragment (including intron) of extremely GC-rich at the 5' or/and 3' flanking regions of these protein genes or their gene promoters. This experiment is the first experimental evidence showing that a non-coding extremely GC-rich DNA fragment is a super "chromatin opening element" and plays an important role in mammalian gene expression. This experiment has further indicated that chromatin-based regulation of mammalian gene expression is at least partially embedded in DNA primary structure, namely DNA GC-content.

[Transplantation of free latissimus dorsi myocutaneous flaps for craniomaxillofacial reconstruction].

OBJECTIVE: This clinical study was to improve the surgical treatment to craniomaxillofacial tissue defects. METHODS: Since 1997, eight cases with severe craniomaxillofacial defects were treated using free latissimus dorsi myocutaneous flaps. In the operation, nerve anastomosis was performed. Of the 8 cases, 7 were treated in one stage, 1 was treated in 3 steps. The craniomaxillofacial defects ranged from 10 cm x 8 cm to 30 cm x 12 cm. The flaps was 12 cm x 10 cm to 32 cm x 16 cm in size. RESULTS: Postoperative follow-up for 6 months to 4 years demonstrated satisfactory results in all the cases. There was neither necrosis nor ulcer after the operation. The sensation recovery of the flap was also satisfactory. CONCLUSION: Free transfer of the latissimus dorsi myocutaneous flap is an ideal treatment to severe craniomaxillofacial defects as it possesses the advantages of reliable blood supply, ability against infections, large size, concealed donor site, and functional restoration of sensation and movement.