施工场地内安全标志位置的有效性研究及其应用

为提高施工场地内安全标志的可见性,选择建筑施工场地内常见的门架式出入口作为研究对象,采取理论推导与实验验证相结合的方法,探讨在观察行为中门架式安全标志的有效布置位置.首先在理论层面,从观察者的角度出发,通过研究行走路径、视野以及安全标志可见域之间的关系,推导出门架式安全标志有效布置区域的理论表示范围;然后在实验验证层面...     

Research progress of nitrous oxide reductase gene (nosZII) and its relationship with the environment北大核心CSCD

The greenhouse effect has become increasingly serious globally. Nitrous oxide (N2O) is both the major ozone depleting substance and a potent greenhouse gas having a global warming potential 298 times that of CO2, and the N2O concentration is still increasing at an annual rate of about 0.8 × 10-9. Nitrous oxide reductase (N2OR) can reduce N2O to N2, and until recently, the nosZ gene was the only gene known to be able to encode N2OR. Besides the well-known nosZI, a new lineage of the N2O-reductase (nosZ clade II), which is abundant and widespread in soils, has been identified. In this paper, the main characters of nosZII-containing microbial communities and the related working mechanisms are summarized. In addition to the main differences between nosZI and nosZII, the important environmental factors that regulate the composition, abundance, and expression of nosZII-containing communities are also discussed in this paper. Studies have shown that nosZII communities are distributed among a diverse range of bacterial and archaeal phyla, such as Epsilon-proteobacteria, Bacteroidetes, and Aquificae. Interestingly, most of the nosZII microbes lack a nitrite reductase encoding gene (nirS or nirK) and are therefore unable to denitrify, indicating the importance of these communities as N2O sinks. Soil properties such as texture, pH, C/ N ratio, temperature, and lake physical gradient could regulate nosZII microbe abundance and diversity, and the pH and C/ N ratio may be the most important influencing factors. Studies on the ecological function of nosZII microbes have advanced considerably with the development of molecular biology technology. However, further studies on the community structure of nosZII microbes, the influencing factors of nosZII microbe abundance and diversity, and characteristics of nosZII strains with strong N2O reducing ability are needed. We hope to provide a theoretical basis that can be used to facilitate N2O reduction and relieve the greenhouse gas problem. © 2018 Science Press. All rights reserved.     

Compliance with recommended protective actions during an H7N9 emergency: a risk perception perspective

This study investigates the factors determining an individual's response to official recommended protective measures, based on the Health Belief Model and the Protective Action Decision Model, to understand the adoption of protective behaviour during an H7N9 (Avian Influenza A) emergency. A public survey involving 1,375 respondents was conducted in Anhui Province, China, during the 2013 H7N9 outbreak to test the research model and hypotheses. The results indicate that protective, stakeholder, and risk perceptions influence positively an individual's willingness to take recommended actions. Protective and stakeholder perceptions also have a positive bearing on lay people's risk perceptions. A stakeholder perception is a vital determinant of a protective perception. More importantly, the effects of protective and stakeholder perceptions on behavioural responses to recommendations are mediated in part by risk perception. These findings can help public health officials to develop messages to encourage members of the population to protect themselves effectively during an influenza crisis.     

安徽淮北矿区地表水氮的富营养化特征及来源解析

为探索淮北临涣矿区地表水体中氮的分布和来源,采集研究区河流和沉陷积水区样品,测试分析其水化学指标和氮、氧同位素特征值,并采用IsoSource模型计算不同端源氮的污染贡献率。结果表明:研究区地表水处于中度富营养化状态,矿区地表水中氮的输入源受含氮肥料、土壤有机氮和粪肥污水共同影响,所发生的硝化及反硝化作用微弱;矿区河水中氮的主要输入源为粪肥污水,贡献率达66.6%,沉陷积水区氮主要受含氮肥料输入的影响,贡献率达52.0%。     

Copeland法与证据权重法在污染物危害性排序上的对比研究

化学物质可能对生态环境或通过不同环境介质对人体健康造成危害。为识别出高危害的污染物,采用Copeland计分排序法和证据权重法,分别选择4、6和8个筛选指标,开展了50种污染物危害特性优先性排序。结果表明:筛选因子数量相同时,2种方法危害性排序结果的斯皮尔曼相关性在0.94以上,具有较好的相关性,可见2种方法均可用于污染物危害性排序;方法相同时,不同指标排序结果之间的相关性相对较小,表明选择不同的筛选指标对结果影响较大。     

TPA下脚料合成增塑剂DOTP的脱色研究

简要介绍了对苯二甲酸（ＴＰＡ）下脚料合成对苯二甲酸二辛酯（ＤＯＴＰ）的工艺路线，着重探讨了深色ＤＯＴＰ的色泽处理方法，优选出物理－化学法作为最佳脱色方法，并确定了最佳操作条件。该法操作简便，产品收率高达８５．４２％，产品质量符合７０℃级电缆料的要求。     

钢铁行业典型HAPs的控制减排

针对钢铁行业有毒有害大气污染物(HAPs)的污染控制难题,以汞和二噁英为典型污染物,论述了钢铁行业HAPs排放特征及控制技术,介绍了HAPs的管控机制,提出了钢铁行业HAPs减排建议。     

Sorption and desorption of naphthalene by soil organic matter: importance of aromatic and aliphatic components

Nonlinear isotherm behavior has been reported for the sorption of hydrophobic organic compounds (HOCs) in soil organic matter (SOM), but the exact mechanisms are unknown. Our objective was to provide insight into the sorption mechanism of HOCs in SOM by studying the sorption-desorption processes of naphthalene in a mineral soil, its humic fractions, and lignin. Additionally, humin and lignin were used for studying the effects of temperature and cosolvent on HOC sorption. All isotherms were nonlinear. The humin and lignin isotherms became more linear at elevated temperatures and with the addition of methanol indicating a condensed to expanded structural phase transition. Isotherm nonlinearity and hysteresis increased in the following order: soil humic acid (HA) < soil < soil humin. Of the samples, aliphatic-rich humin exhibited the largest degree of nonlinearity and had the highest sorption capacity for naphthalene. High nonlinearity and hysteresis in humin were most likely caused by its condensed structure. A novel aliphatic, amorphous condensed conformation is proposed. This conformation can account for both high sorption capacities and increased nonlinearity observed for aliphatic-rich samples and can explain many sorption disparities discussed in the literature. This study clearly illustrates the importance of both aliphatic and aromatic moieties for HOC sorption in SOM.     

ANN模型对污水处理系统性能的评价

作者基于B－P算法的人工神经网络，对污水处理系统的性能作了预测和评价，并通过所建立的一个生物转盘处理系统的人工神经网络预测模型实例，验证了人工神经网络用于污水处理系统性能评价方面的可行性与准确性。