环境治理中光催化剂的失活与再生

催化剂失活是影响光催化过程用于污染治理经济实用的关键因素。对近几年来国内外环境污染控制中光催化剂的失活现象及其原因进行了综述．分析了液相和气相光催化反应体系中催化剂失活后再生的方法．特别是对气相光催化反应中水蒸汽的影响进行了讨论。     

Validating graph-based connectivity models with independent presence–absence and genetic data sets

Habitat connectivity is a key objective of current conservation policies and is commonly modeled by landscape graphs (i.e., sets of habitat patches [nodes] connected by potential dispersal paths [links]). These graphs are often built based on expert opinion or species distribution models (SDMs) and therefore lack empirical validation from data more closely reflecting functional connectivity. Accordingly, we tested whether landscape graphs reflect how habitat connectivity influences gene flow, which is one of the main ecoevolutionary processes. To that purpose, we modeled the habitat network of a forest bird (plumbeous warbler [Setophaga plumbea]) on Guadeloupe with graphs based on expert opinion, Jacobs’ specialization indices, and an SDM. We used genetic data (712 birds from 27 populations) to compute local genetic indices and pairwise genetic distances. Finally, we assessed the relationships between genetic distances or indices and cost distances or connectivity metrics with maximum-likelihood population-effects distance models and Spearman correlations between metrics. Overall, the landscape graphs reliably reflected the influence of connectivity on population genetic structure; validation R² was up to 0.30 and correlation coefficients were up to 0.71. Yet, the relationship among graph ecological relevance, data requirements, and construction and analysis methods was not straightforward because the graph based on the most complex construction method (species distribution modeling) sometimes had less ecological relevance than the others. Cross-validation methods and sensitivity analyzes allowed us to make the advantages and limitations of each construction method spatially explicit. We confirmed the relevance of landscape graphs for conservation modeling but recommend a case-specific consideration of the cost-effectiveness of their construction methods. We hope the replication of independent validation approaches across species and landscapes will strengthen the ecological relevance of connectivity models.     

Patient demands,lack of reciprocity,and burnout: a five‐year longitudinal study among general practitioners

This study among a sample of 207 general practitioners (GPs) uses a five‐year longitudinal design to test a process model of burnout. On the basis of social exchange and equity theory, it is hypothesized and found that demanding patient contacts produce a lack of reciprocity in the GP–patient relationship, which, in turn, depletes GPs' emotional resources and initiates the burnout syndrome. More specifically, structural equation analyses confirmed that—both at T1 and T2—lack of reciprocity mediates the impact of patient demands on emotional exhaustion. Emotional exhaustion, in turn, evokes negative attitudes toward patients (depersonalization), and toward oneself in relation to the job (reduced personal accomplishment). Moreover, this process model of burnout was confirmed at T2, even after controlling for T1‐scores on each of the model components. Finally, T1 depersonalization predicted the intensity and frequency of T2 patient demands, after controlling for T1 patient demands. This major finding suggests that GPs who attempt to gain emotional distance from their patients as a way of coping with their exhaustion, evoke demanding and threatening patient behaviors themselves. The theoretical and practical implications of these findings are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Occurrence and volatility of several trace elements in pulverized coal boiler

The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements‘ characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1. Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2. Cr has properties of both group ! and 3. In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements (except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.     

北京市几所高校校园安全调查报告

校园安全事关师生人身安全和学校的财产安全,事关教育改革、发展、稳定的大局,加强首都校园安全管理的意义重大。以典型北京高校为例,通过调查研究的方法,客观分析当前首都高校的安全现状,给出开展校园安全管理的基本对策。     

炼钢精炼渣气固碳酸化反应吸附CO2

采用炼钢精炼渣,通过气固碳酸化反应吸附CO₂,考察了不同吸附温度下精炼渣对纯CO₂和模拟高炉煤气中CO₂的吸附能力。实验结果表明：吸附温度对精炼渣吸附CO₂反应有显著的影响,升高温度可以提高精炼渣对CO₂的吸附能力;在400 ℃时,精炼渣吸附纯CO₂和模拟高炉煤气中CO₂的量分别为4.7 mg/g和9.8 mg/g;吸附温度升高到500 ℃和550 ℃时,精炼渣对纯CO₂的吸附能力强于高炉煤气中CO₂;在550 ℃时,精炼渣吸附纯CO₂和模拟高炉煤气中CO₂的量达到最高,分别为14.7 mg/g和12.9 mg/g。     

Treatment of drilling fluid waste during oil and gas drilling: a review

Environmental Science and Pollution Research - Oil and gas exploration and development provide important energy sources for the world, and drilling fluid is an essential engineering material for...     

Industrial production of recycled cement: energy consumption and carbon dioxide emission estimation

Environmental Science and Pollution Research - The urge to reduce greenhouse gas emissions, in particular carbon dioxide, is a global problem, not only in spatial terms but also in terms of the...     

软锰矿浆烟气脱硫反应器试验研究

研究了喷射鼓泡反应器 (JBR)的桨叶直径、桨叶埋深和气体喷射管分布等结构参数对脱硫率和锰浸出率的影响 ,从而优化了反应器结构。