活性氧参与多壁碳纳米管诱导的RAW264.7细胞毒性

碳纳米管以其独特的结构和性能,在生物医药和电子等领域广泛应用,而其生态安全性也成为科学界关注的焦点。为探究多壁碳纳米管(MWCNTs)诱导的细胞毒性机制,将小鼠肺泡巨噬细胞(RAW264.7)暴露于6个浓度梯度(0、25、50、100、150和200μg.mL-1)的MWCNTs中,应用噻唑蓝(MTT)法测定细胞存活率,用2’,7’-二氯荧光素二乙酸(DCFH-DA)荧光染色法测定细胞内活性氧的生产量,用流式细胞方法测定MWCNTs对细胞周期的影响。同时使用抗氧化剂氮乙酰半胱氨酸(NAC)验证MWCNTs诱导的细胞氧化损伤的作用机理。结果显示,MWCNTs对RAW264.7的细胞毒性呈剂量依赖性。暴露于不同浓度的MWCNTs(25、50、100、150和200μg.mL-1)下24h后,细胞活力分别为对照的74%、62%、59%、51%和45%。MWCNTs对RAW264.7的周期阻滞作用主要发生在G0/G1期。200μg.mL-1的MWCNTs处理3h后活性氧较对照组上升6.6倍。NAC对MWCNTs细胞毒作用有明显的抑制作用,且NAC能减弱MWCNTs对RAW264.7的细胞周期阻滞作用。研究表明,活性氧能够介导MWCNTs对小鼠巨噬细胞RAW264.7的损伤,并且MWCNTS通过细胞周期G0/G1期的阻滞,诱导细胞凋亡。     

实施最严格的野生动物保护:中国现状与改革方向

随着全球工业化和城市化的快速发展,野生动物及其栖息地保护面临着前所未有的挑战。本文识别了我国的野生动物保护存在的主要问题:(1)现行《野生动物保护法》对野生动物保护范围界定过窄,资源利用主导思维干扰了野生动物保护,缺乏对生态系统与生物安全的足够重视。(2)由于现行野生动物保护立法、执法和管理制度不健全甚至缺失,导致野生动物驯养繁殖交易市场长期混乱,甚至成为非法野生动物交易的"洗白工具"。(3)社会公众群体尊重和保护野生动物意识淡薄,全民参与和监督举报机制不健全。本文认为,我国应该实施最严格的野生动物保护制度,实现人与野生动物平等、文明、和谐相处,建议:(1)树立尊重野生动物物种生存权、人与野生动物文明和谐相处的理念,摒弃野生动物资源利用观,重构人与野生动物平等共存关系。(2)清晰界定野生动物法律定义,扩大野生动物保护范围,围绕捕猎、繁育、运输、储存、转让、食用等环节,全面、科学、精准地构建最严格的野生动物保护制度。(3)立足于全面保护野生动物,严格禁止滥食滥用野生动物和过度商业化利用,实行野生动物保护利用特许制度,并大幅提高标准严格控制交易和利用,建立职责清晰的执法监管和惩治体系。(4)建立最严格的野生动物保护公众参与和司法治理体系,实施野生动物非法贸易、猎杀的行政公益诉讼制度,引导公众建立爱护保护野生动物、不食不用野生动物的文明行为,最终实现人类社会与野生动物的文明和谐共处。     

Population structure and community characteristics of Acer catalpifolium Rehd北大核心CSCD

Acer catalpifolium Rehd., a critically endangered tree species with an extremely limited range of distribution, is one of the 120 plant species with extremely small populations, as approved by the state forestry administration of the People's Republic of China and requires urgent rescue action. In order to comprehensively understand the population status and the future developmental trend of A. catalpifolium, the plant communities were investigated from 5 sites, including Caishenmiao (CSM), Banruosi (BRS), Zhangshancun (ZSC), Fuhusi (FHS), and Baoguosi (BGS). The population structure of A. catalpifolium as well as the species composition and community characteristics of its habitat were investigated. The results showed that A. catalpifolium is mainly distributed in the evergreen broad-leaved and deciduous broad-leaved mixed forests, in different community layers, namely, the tree layer, shrub layer, and herb layer, and is accompanied by 52, 74, and 52 plant species, respectively. Analyses of the distribution of population abundance revealed that BRS had the largest distribution of A. catalpifolium, accounting for 26.04% of the total population, followed by FHS, ZSC, BGS, and CSM, in that order. Analyses of the community characteristics revealed that the species diversity indices in FHS, BRS, BGS, and CSM were greater than that in ZSC. Analyses of the population age structure of A. catalpifolium revealed the gap in the distribution of the levels of seedlings and young trees. There were serious obstacles to the regeneration of the natural population. We concluded that the obstacle to the regeneration of the population of A. catalpifolium might be caused by the high competitive pressure from the dominant species and the micro-environment in the forest. Understanding the community characteristics and the population structure of A. catalpifolium could provide a theoretical foundation for its reintroduction and recovery. © 2018 Science Press. All rights reserved.     

Tolerance of the black soldier fly,Hermetia illucens (Diptera: Stratiomyidae) to pH value,pungency, and NaCl in foodstuffs北大核心CSCD

The black soldier fly (BSF), Hermetia illucens, has been considered impressive as a saprophagous insect, for its high ability to convert organic waste to insect protein and oil. Hence, it has been regarded by the municipal administration that BSF might be used as a medium to deal with food waste. However, food waste in China has been characterized as having a high salt content, oily, and very spicy, which usually renders them unsuitable for animal feeding. In order to assess the technological reliability for BSF conversion of food waste, the tolerance of BSF for pH values, pungency, and NaCl in food were investigated in this case. Results indicated that strong acidity (pH = 3) was not good for the development of BSF, demonstrating less body weight and eclosion failure. In contrast, strong basicity (pH = 11) seemed to be beneficial for larval development with high biomass, and there is no difference in pupation, eclosion, larval biomass, and livability for BSF for pH values between 5 and 11. With regards to salinity, liner correlations were observed; the salinity strength increased along with the extension of the larval phase, but body weight, pupation rate, emerging rate, and livability were still consistent under 6% density of salinity. Influence of pungency on BSF larvae has not yet been found. In conclusion, BSF showed a high tolerance to pH value, pungency, and salinity in foodstuffs. Hence, it is expected that food waste from common environments might have a lesser possibility to cause negative effects on BSF development, which could be good news for BSF conversion technology. As for the process design, the conclusion suggested that food waste optimum for BSF is expected to be alkaline and low-salt, which would be helpful to improve the efficiency and harvest. © 2018 Science Press. All rights reserved.     

污泥龄对LSP & PNR污泥减量新工艺运行效能的影响

通过研究分析污泥龄（SRT）对富磷污水除磷的LSP&PNR污泥减量新工艺运行效果的影响,结果发现,延长污泥龄有利于提高系统的厌氧释磷能力,但不影响其总的除磷率,同时磷的回收比例增大,当SRT=50 d时,磷回收率取得最大值70.4％;LSP&PNR系统污泥龄增加,还有利于污泥产率的降低。试验还发现,排富磷污水除磷的长污泥龄LSP&PNR系统的除磷效率与污泥产率之间不存在制约关系,即系统可以同时获得优异的污泥减量与生物除磷效果,当SRT=50 d时,每降解1 kg COD仅产生0.143 kg污泥,而除磷率达最高值928％;LSP&PNR系统中SRT、DO与SVI之间存在一定的相关性,在供氧充足（DO＝0.8～1.5 mg/L）条件下,SRT增加,SVI越高,但对于SRT为50 d的LSP&PNR系统,稳定运行时没有污泥膨胀之虞。     

污泥龄对LSP & PNR污泥减量新工艺运行效能的影响

通过研究分析污泥龄(SRT)对富磷污水除磷的LSP&PNR污泥减量新工艺运行效果的影响,结果发现,延长污泥龄有利于提高系统的厌氧释磷能力,但不影响其总的除磷率,同时磷的回收比例增大,当SRT=50 d时,磷回收率取得最大值70.4%;LSP&PNR系统污泥龄增加,还有利于污泥产率的降低.试验还发现,排富磷污水除磷的长污泥龄LSP&PNR系统的除磷效率与污泥产率之间不存在制约关系,即系统可以同时获得优异的污泥减量与生物除磷效果,当SRT=50 d时,每降解1 kg COD仅产生0.143 kg污泥,而除磷率达最高值92.8%;LSP&PNR系统中SRT、DO与SVI之间存在一定的相关性,在供氧充足(DO=0.8～1.5 mg/L)条件下,SRT增加,SVI越高,但对于SRT为50 d的LSP&PNR系统,稳定运行时没有污泥膨胀之虞.     

A directional passive air sampler for monitoring polycyclic aromatic hydrocarbons (PAHs) in air mass

A passive air sampler was developed for collecting polycyclic aromatic hydrocarbons (PAHs) in air mass from various directions. The airflow velocity within the sampler was assessed for its responses to ambient wind speed and direction. The sampler was examined for trapped particles, evaluated quantitatively for influence of airflow velocity and temperature on PAH uptake, examined for PAH uptake kinetics, calibrated against active sampling, and finally tested in the field. The airflow volume passing the sampler was linearly proportional to ambient wind speed and sensitive to wind direction. The uptake rate for an individual PAH was a function of airflow velocity, temperature and the octanol-air partitioning coefficient of the PAH. For all PAHs with more than two rings, the passive sampler operated in a linear uptake phase for three weeks. Different PAH concentrations were obtained in air masses from different directions in the field test.     

Recent advances in the photocatalytic reduction of carbon dioxide

Fossil fuels are currently the major energy source and are rapidly consumed to supply the increasing energy demands of mankind. CO₂, a product of fossil fuel combustion, leads to climate change and will have a serious impact on our environment. There is an increasing need to mitigate CO₂ emissions using carbon–neutral energy sources. Therefore, research activities are devoted to CO₂ capture, storage and utilization. For instance, photocatalytic reduction of CO₂ into hydrocarbon fuels is a promising avenue to recycle carbon dioxide. Here we review the present status of the emission and utilization of CO₂. Then we review the photocatalytic conversion of CO₂ by TiO₂, modified TiO₂ and non-titanium metal oxides. Finally, the challenges and prospects for further development of CO₂ photocatalytic reduction are presented.     

Removal of elemental mercury by KI-impregnated clay

This study described the use of clay impregnated by KI in gas phase elemental mercury (Hg^o) removal in flue gas. The effects of KI loading, temperature, O₂, SO₂ and H₂O on Hg^o removal were investigated using a fixed bed reactor. The Hg^o removal efficiency of KI-clay with 3% KI loading could maintain at a high level (approximately 80 %) after 3 h. The KI-clay demonstrated to be a potential adsorbent for Hg^o removal when compared with activated carbon based adsorbent. O₂ was found to be an important factor in improving the Hg^o removal. O₂ was demonstrated to assist the transfer of KI to I₂ on the surface of KI-clay, which could react with Hg^o directly. NO and SO₂ could slightly improve Hg^o removal, while H₂O inhibited it greatly. The results indicated that after adsorption, most of the mercury escaped from the surface again. Some of the mercury may have been oxidized as it left the surface. The results demonstrated that the chemical reaction primarily occurred between KI and mercury on the surface of the KI-clay.     

Improving simulations of sulfate aerosols during winter haze over Northern China: the impacts of heterogeneous oxidation by NO<Subscript>2</Subscript>

We implemented the online coupled WRF-Chem model to reproduce the 2013 January haze event in North China, and evaluated simulated meteorological and chemical fields using multiple observations. The comparisons suggest that temperature and relative humidity (RH) were simulated well (mean biases are–0.2K and 2.7%, respectively), but wind speeds were overestimated (mean bias is 0.5 m?s^–1). At the Beijing station, sulfur dioxide (SO₂) concentrations were overpredicted and sulfate concentrations were largely underpredicted, which may result from uncertainties in SO₂ emissions and missing heterogeneous oxidation in current model. We conducted three parallel experiments to examine the impacts of doubling SO₂ emissions and incorporating heterogeneous oxidation of dissolved SO₂ by nitrogen dioxide (NO₂) on sulfate formation during winter haze. The results suggest that doubling SO₂ emissions do not significantly affect sulfate concentrations, but adding heterogeneous oxidation of dissolved SO₂ by NO₂ substantially improve simulations of sulfate and other inorganic aerosols. Although the enhanced SO₂ to sulfate conversion in the HetS (heterogeneous oxidation by NO₂) case reduces SO₂ concentrations, it is still largely overestimated by the model, indicating the overestimations of SO₂ concentrations in the North China Plain (NCP) are mostly due to errors in SO₂ emission inventory.

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