微波消解-分光光度法测定COD的研究

通过试验研究,提出了测定COD的新方法——微波消解-分光光度法。该方法准确度、精密度符合分析要求,与国标中回流法的测定结果没有显著差异。而且采用该方法测定COD可克服回流法、微波消解-滴定法及HACH-COD测定法的操作复杂、耗时长等缺点。     

Removal of Linear and Branched p-Alkylphenols from Aqueous Solution by Combined Use of melB Tyrosinase and Chitosan Beads

In this study, melB tyrosinase was applied for enzymatic removal of linear and branched p-alkylphenols from aqueous solutions. First, systematic studies were carried out to estimate the effects of the process parameters such as the temperature, pH value, and enzyme dose on quinone conversion of p-cresol as a model phenol compound. A variety of p-alkylphenols were removed from aqueous solutions through the tyrosinase-catalyzed quinone conversion and subsequent nonenzymatic adsorption of quinone derivatives on chitosan beads at pH 6.0 and 30 °C under the optimum conditions determined for p-cresol. The % removal values of 98–100 were obtained for p-n-alkylphenols. Branched p-alkylphenols with a weak estrogenic activity containing 4-tert-butylphenol and 4-tert-pentylphenol, which underwent no quinone conversion by commercially available mushroom tyrosinase in the absence of H₂O₂, were also effectively removed by further increasing either the melB tyrosinase concentration or the amount of added chitosan beads. The present technique is much effective in the fact that a series of reactions rapidly progress under mild conditions and the chitosan beads can be readily separated from the reaction medium after the enzymatic treatment.     

Dietary patterns and blood levels of PCDDs, PCDFs, and dioxin-like PCBs in 1656 Japanese individuals

The association between dietary patterns and blood dioxin levels has not been fully investigated. The present study population consisted of 755 men and 901 women (aged 15-73 years) living in 90 different areas of 30 prefectures of Japan. Dietary habits were assessed by inquiring about the consumption frequency of 28 foods, food groups and beverages. In addition, the blood levels of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs), and dioxin-like polychlorinated biphenyl (DL-PCBs) congeners were determined by high-resolution gas chromatography/mass spectrometry. The median total toxicity equivalent (TEQ) in the blood, which was calculated on the basis of the toxicity equivalency factors of WHO (2005), was 16 pg TEQ g⁻¹ lipid. Principal component analysis identified five dietary patterns: Healthy diet (high intake of vegetables and fruits); Meat/High fat intake (high intake of meat, meat products, and eggs); Seafood and Alcohol (high intake of fish, shellfish, and alcoholic beverages); Miscellaneous; and Milk products and Alcohol intake (high intake of milk, Milk products, and alcoholic beverages). After adjusting for sex, age, body mass index, and smoking habits, the Seafood and Alcohol pattern scores were significantly related to higher blood levels of total TEQ and PCDDs/PCDFs/DL-PCBs, and the Milk products and Alcohol pattern scores were correlated with higher blood levels of DL-PCBs. More detailed analysis showed that the intake frequencies for alcoholic beverages and seafood were independently and positively associated with total TEQ and the TEQ of PCDFs and DL-PCBs. The association between alcoholic beverage intake and PCDDs was also significant. Analysis of dietary patterns may be useful for identifying the dietary characteristics of individuals with a high dioxin body burden.     

VISUAL PROPERTIES AND AFFECTIVE APPRAISALS IN RESIDENTIAL AREAS AFTER DARK

The present study examined multiple relationships within and between two sets of variables — visual properties and affective appraisals — in night-time neighbourhood experience. Twenty-eight participants rated twenty night-time neighbourhood scenes on 12 visual property variables and six affective appraisal variables. Canonical correlation revealed relationships between evaluative and natural/open dimensions, arousal and disorder dimensions, and between behavioural active/safe and well-lit/visible dimensions.     

Correspondence analysis of paper recycling society: consumers and paper makers in Japan

Paper passes through many hands. In the present paper, key parts of this cycle in Japan were examined, using questionnaire surveys of households and paper makers. The study aimed to examine the paper makers' strategy for paper production and their attitude to recycling, in comparison with those of the consumers. The study especially focused on toilet paper because consumers have a lot of freedom in purchasing toilet paper. A total of 1242 consumers and 60 paper makers responded. The major findings were as follows. First, we compared the criteria of consumers for purchasing toilet paper with the conjectures of paper makers. Brand, advertisements and the appearance of shopping displays received 60% support from paper makers, but less than 12% of consumers selected these criteria even if we exclude those who do not buy toilet paper or do not have any particular criteria. On the other hand, multiple plies and benefit to the earth were selected by moderate numbers (between 20 and 25%) of consumers, while only 16.77 and 5.69%, respectively of paper makers marked these criteria. Paper makers strongly believe that many retailers sell toilet paper as a loss-leader. By comparing those matters considered important for recycling by consumers with those considered important by makers, it was shown that many makers have a clear awareness of the particular problem, the lack of used paper consumption, in the current paper recycling situation in Japan.     

核桃青皮生物炭对重金属铅、铜的吸附特性研究

采用500℃限氧裂解法将农林废弃物核桃青皮制成核桃青皮生物炭,进行了核桃青皮生物炭对铅、铜的批量吸附实验.同时,利用扫描电镜、FTIR红外等方法探讨了核桃青皮炭吸附Pb~(2+)、Cu~(2+)的特性,探究了吸附时间、溶液初始浓度、吸附温度、吸附剂投加量、溶液初始pH等因素对核桃青皮生物炭吸附Pb~(2+)、Cu~(2+)作用的影响,讨论了吸附动力学特性及吸附等温特性.结果表明:温度298.15 K、pH为3~6条件下,核桃青皮生物炭吸附Pb~(2+)和Cu~(2+)在20 min内即可达到吸附平衡,核桃青皮炭最佳投加量分别为0.8、1.5 g·L~(-1),最大吸附量分别为476.190、153.846 mg·g~(-1);吸附过程符合准二级动力学方程,等温吸附曲线符合Langmuir方程,说明其吸附过程主要是近似单分子层的化学吸附.     

Scale effect of flame instability mechanisms on propagation velocity

Blast pressure is a major source of the damage caused by an accidental gas explosion. Its magnitude depends on the thermal expansion rate and hence on the flame propagation velocity. This paper discusses the influence of two flame instability mechanisms, i.e., diffusive-thermal and hydrodynamic instabilities, on flame propagation velocity with an emphasis on their scale effects as the flame continuously increases its size during an explosion. The Sivashinsky equation is numerically solved to simulate flame propagation behaviors. It is found that flame propagation velocity, V_f, is independent of flame size under the influence of diffusive-thermal instability, whereas V_f increases with flame size under the influence of hydrodynamic instability. The latter result is understood as a result of flame’s fractal structure. Fractal dimension is determined from the dependency of V_f on flame size, and the obtained fractal dimension is close to the known experimental value.     

环境样品中多氯联苯的生物检测方法研究进展

多氯联苯(PCBs)是一种环境中广泛存在的典型的持久性有毒有机污染物.对人类和环境产生了许多有害影响.随着对多氯联苯的研究越来越广泛,其监测方法研究发展得也很快.本文综述了近些年来国内外 采用的多种多氯联苯的分析方法.特别介绍了酶联免疫法、生物传感器法、荧光免疫PCR等近年来发展迅速的检测技术的研究情况.比较了各种免疫...