色谱质谱联用技术在一起农药污染事故应急监测中的应用

在一起污染源应急事故中,色谱质谱联用技术在确定污染源类型,并快速做出准确定性定量分析中发挥了重要作用。通过气相色谱-质谱联用技术,首先确定可能污染物类型为三嗪类化合物;之后,通过液相色谱-串连质谱全扫描,推断可能为三嗪类除草剂——甲磺隆。正、负ESI子离子全扫描后图谱与甲磺隆标准物质图谱相对照,完全吻合。最后,通过SRM模式下对380.0→139.0的母、子离子选择反应监测,测定了农田灌溉水源和土壤中甲磺隆的含量。     

壳聚糖-丙烯酰胺-二甲基二烯丙基氯化铵三元接枝共聚物的合成及应用

在N2保护下,以硝硬驱铈铵为引发剂,将壳聚糖（CTS）、丙烯酰胺（AM）及二甲基二烯丙基氯化铵（DMDAAC）接枝共聚得到CTS-AM-DMDAAC三元接枝共聚物,考察了反应条件对接枝共聚反应的影响。实验结果表明,在反应温度50℃、反应时间5-6h,m（CTS）：m（AM）：m（DMAAAC）=1：6：0.67、c（Ce^4＋）=0.8mmol/L的最佳反应条件下,接枝共聚反应的接枝率和接枝效率分别为64%和10.5%。用傅里叶变换红外光谱仪对CTS-AM-DMDAAC进行了表征。絮凝实验结果表明：CTS-AM-DMDAAC对高岭土水样具有较强的絮凝能力,可在很宽的pH范围内使用。用CTS-AM-DMDAAC处理COD为165.5mg/L的啤酒生产废水,COD去除率达90.1%.     

基于文献计量法的火灾灾害研究现状及展望

为了解火灾灾害研究领域的发展现状及未来趋势,基于多种可视化工具,对2014—2020年期间,火灾灾害领域内的发文态势、学术合作、学术热点、研究趋势等内容展开分析。研究结果表明：该时期内,火灾领域发文量呈持续上升趋势;我国科研活力及持续发展性均处于世界前沿地位,中国科学技术大学是全球发文量和合作活跃度较高的机构;载发文量排名前5的期刊研究方向和出刊数量整体呈现出一定差异性和波动性;研究热点涵盖基于无人飞行器的森林火灾(野火)侦测调查、基于火灾现场整体模型搭建的计算机模拟火灾事故技术与研究、火灾下建筑物构件的耐火及倒塌行为研究、池火燃烧特性试验及现象调查、火灾碎片实验与分析方法,研究内容总体呈现具体化、精细化;目前火灾领域研究的前沿方向为热释放速率研究、基于数值模拟的火灾事故研究、对点火器(源)的调查研究、基于数值模拟的火灾事故调查等;根据分析推测该领域未来的科研活跃度将继续上升。研究结果可为火灾灾害领域内相关学者把握学科现状,研讨未来发展提供参考依据。     

Living with nuclear power: Sense of place,proximity, and risk perceptions in local host communities

Previous research notes that sense of place may intensify, and that levels of public risk perception may decrease with proximity to an established hazardous or stigmatised site. In addition, the literature suggests that sense of place may act either to mediate or moderate community perceptions of risk in such localities. This study comprised a major household survey (n = 1326) and an interview study (n = 39) and was conducted close to the nuclear power stations at Oldbury and Hinkley Point, both in the UK. It investigated the roles of perceptions of place and hazard proximity in considering (a) perceptions of risk and (b) public attitudes towards the building of a new nuclear power station in the nearby area. In addition, a novel scale was developed to measure the perceived contribution of the nearby nuclear power station to sense of place. The results suggest first, that sense of place mediates (but does not moderate) perceptions of risk in very proximate communities, and second, that public attitudes to new build in communities situated very close to established nuclear sites may be largely dependent on the extent to which the existing facility is perceived to contribute towards sense of place. The implications of these results for existing theory are discussed.     

针铁矿及腐残质对水体重金属离子的吸附作用

采用针铁矿、腐殖质,针铁矿－腐殖复合微粒对重合微粒对重金属离子进行了吸附－解吸实验。结果表明它们对Cu^2 ,Zn^2 有强烈的吸附作用。针铁矿对Cu^2 和Zn^2 的吸附边界pH值分别为4．3和5．8,且吸附率可达95％以上。腐殖质对Cu^2 和Zn^2 的吸附边界pH值分别为4．1和5．6,且在pH值为8时,吸附率可达96％以上。针铁矿与腐殖形成的稳定复合微粒不仅对重金属离子具有良好的吸附作用,还具有均匀性好和沉降稳定的特点,可用于土壤修复和含重金属离子的污水的处理。     

Ecosystem service tradeoff between traditional and modern agriculture: a case study in Congjiang County, Guizhou Province, China

Besides crops, agriculture supplies all three major categories of ecosystem services (ES). However, agriculture also supplies an array of ecosystem dis-services (EDS) that may harm other ecosystems. The flows of ES and EDS are directly dependent on the management of agricultural ecosystems. The traditional method of Chinese agriculture, which supports sustainable agriculture, has been proven to increase ES and reduce EDS. However, there is a lack of a detailed understanding of the ES and EDS associated with traditional agriculture, and also of differences between traditional and modern agriculture. In this study, an investigation was conducted on the ecosystem services (ES) and ecosystem dis-services (EDS) of traditional and modern agriculture in Congjiang County, Guizhou Province, China. Afterwards, the economic values of ES and EDS were quantified experimentally and calculated based on the market price. The results show that: the net economic value of traditional rice-fish agriculture was 3.31×10⁴ CNY·ha^?1 (6.83 CNY = 1 USD as of July, 2009) and that of rice monoculture was 1.99×10⁴ CNY·ha^?1. Significant differences existed between traditional rice-fish and rice monoculture fields for their economic values of some ES or EDS. A benefit and cost analysis (BCA) model was used to adjust the conflict between the economic income and environmental loss from traditional and modern agriculture. The BCA model not only calculates the net income but also monetizes the EDS of the agricultural systems. The results showed that the net income of rice-fish agriculture was 1.94×10⁴ CNY·ha^?1 higher than that of rice monoculture. However, the benefit to cost ratio (BCR) of rice-fish agriculture was lower than that of rice monoculture, indicating that the traditional agricultural model was not the most optimized choice for farmers. The value of the rice-fish agriculture was much higher than that of the rice monoculture. Thus, when considering the benefits that rice-fish agriculture contributes to the largescale society, these agricultural methods needs to be utilized. Furthermore, the labor opportunity costs were calculated and the comprehensive value of rice monoculture was negative. Finally, the compensation standard was calculated based on the comprehensive benefit analysis. The lowest level was 1.09×10³ CNY·ha^?1, and the highest level was 1.21×10⁴ CNY·ha^?1.     

Research on transesterification parameters for producing plant sterols with supercritical methanol

The supercritical fluid method, regarded as a type of individual production process in the course of preparing plant sterols, has become a promising technology, which possesses advantages of high conversion rate without any pretreatment and need of a catalyst. This study examined the reaction process of the deodorizer distillate (DOD), which mainly included the direct transesterification of DOD to convert into free sterols. The effects of the ratio of methanol to DOD, reaction temperature and time on transesterification were studied. Furthermore, the interactions between different factors were also assessed using the response surface methodology. The optimal conditions obtained were as follows: reaction temperature 553 K, reaction time 80 min, and CH₃OH: DOD = 25:1 (mass ratio). Under these conditions, 36.42% sterol concentration was obtained, which is significantly higher in comparison with the initial sterols’ concentration in raw material (22.45%).     

基于BP神经网络的天线识别

本文比较研究了BP神经网络中的几种常用算法,针对这些不同算法下的BP神经网络进行训练,并得出了各自网络的性能。在此基础上,针对经典BP算法和LM算法进行对比研究,找到LM算法的改进之处。此外,在实际的应用中表明,不仅不同的BP算法对网络的运算速度、泛化能力等有较大的影响,而且BP神经网络对隐含层神经元数目也很敏感。我们希望在BP神经网络的基础上,构建一种合适的天线模型,来应用于天线的分类识别,这将具有很大的现实意义。