低氮燃烧器改造与燃烧调整试验

针对大唐太原第二热电厂300 MW空冷供热机组NOx排放浓度超标问题,进行了燃烧器低氮燃烧技术改造,并先后进行了以稳燃和以降低NOx排放浓度为目的的燃烧调整试验,试验结果表明,燃烧稳定性能得到提高,NOx排放浓度明显降低,但距将于2014年7月1日起实施的火电厂大气污染物排放标准(GB13223-2011)限值还有一定差距,为此建议,需采用烟气脱销技术进一步降低NOx排放浓度以满足国家标准。     

Experimental Investigation on Electrical Tracking of Epoxy Resin Compound with Silicon Rubber

The use of polymer materials as electrical insulators on transmission and distribution lines has been increas- ing such,as epoxy resin. Several advantages of using epoxy resin as an insulating material...     

Evaluation of ITS PCR and RFLP for Differentiation and Identification of Brewing Yeast and Brewery ‘Wild’ Yeast Contaminants

A reference library of ITS PCR/RFLP profiles was collated and augmented to evaluate its potential for routine identification of domestic brewing yeast and known ‘wild’ yeast contaminants associated with wort, beer and brewing processes. This library contains information on band sizes generated by restriction digestion of the ribosomal RNA‐encoding DNA (rDNA) internal transcribed spacer (ITS) region consisting of the 5.8 rRNA gene and two flanking regions (ITS1 and ITS2) with the endonucleases CfoI, HaeIII, HinfI and includes strains from 39 non‐Saccharomyces yeast species as well as for brewing and non‐brewing strains of Saccharomyces. The efficacy of the technique was assessed by isolation of 59 wild yeasts from industrial fermentation vessels and conditioning tanks and by matching their ITS amplicon sizes and RFLP profiles with those of the constructed library. Five separate, non‐introduced yeast taxa were putatively identified. These included Pichia species, which were associated with conditioning tanks and Saccharomyces species isolated from fermentation vessels. Strains of the lager yeast S. pastorianus could be reliably identified as belonging to either the Saaz or Frohberg hybrid group by restriction digestion of the ITS amplicon with the enzyme HaeIII. Frohberg group strains could be further sub‐grouped depending on restriction profiles generated with HinfI.     

低渗透油田提高单井产量技术应用及评价

油水井在修井、开采过程中造成地层污染,产量下降,为了稳定并提高单井产量,开展了堵塞机理研究、低产原因分析、不同油藏工艺措施优选等研究与应用,近几年主要采取的措施类型主要有土酸酸化、暂堵酸化、乳化酸酸化等措施类型,但随着油田开发时间的延长,油井含水上升,堵塞类型复杂,并且油井措施次数增加,部分井采取常规酸化已经达不到增油降水的目的,因此引进多氢酸酸化、负压返排工艺、泡沫酸酸化、潜在酸酸化等措施,目的在于减缓酸岩反应速度、提高酸化后残液的返排率,减缓油井含水上升速度。     

基于声发射特性的玻璃绝缘子污闪预测模型

绝缘子污秽闪络是电力系统不可忽视的灾害之一,绝缘子污秽局部放电声信号可以有效反映绝缘子接近污闪的“危险情况”。首先,在人工污秽实验室内进行大量试验,模拟不同可溶污秽附着密度(soluble contamination density,SCD)、不同灰密对玻璃绝缘子声发射信号的影响。之后,提取了污秽放电声发射信号2个典型特征量并分析了其变化规律。然后,建立了基于广义回归神经网络(general regression neural network,GRNN)的绝缘子外绝缘危险度预测模型,提取7个有效声发射特征量作为GRNN模型的输入,以绝缘子污秽闪络的危险度系数作为输出,得到不同可溶物、不同SCD下的预测结果。结果表明:基于声发射特性的GRNN预测模型准确性较高,声发射特征量的变化受到SCD的影响较大,SCD越低,特征量随机性变化越大,GRNN模型的预测准确性随之降低。所提模型为不同污秽度地区采用声发射测量法监测绝缘子外绝缘状况提供了可信度参考。     

Short communication: Inactivation of microbial contaminants in raw milk La Serena cheese by high-pressure treatments

La Serena cheese, a Spanish variety made from Merino ewes’ raw milk, has a high pH value, low salt content, and high moisture, conditions that are all favorable for growth and survival of contaminating microorganisms, including pathogens. To improve its microbiological quality and safety, high-pressure treatments at 300 or 400 MPa for 10 min at 10°C were applied to 2 batches of La Serena cheese on d 2 or 50 of ripening. Cheese treated on d 2 at 300 MPa showed viable aerobic counts that were 0.99 log units lower than those for control cheese on d 3 and showed counts of enterococci, coagulase-positive staphylococci, gram-negative bacteria, and coliforms that were 2.05, 0.49, 3.14, and 4.13 log units lower, respectively, than control cheese. For cheese treated on d 2 at 400 MPa, the respective reductions in counts were 2.02, 2.68, 1.45, 3.96, and 5.50 log units. On d 60, viable aerobic counts in cheese treated on d 50 at 300 MPa were 0.50 log units lower than those in control cheese, and counts of enterococci, gram-negative bacteria, and coliforms were 1.37, 2.30, and 4.85 log units lower, respectively. For cheese treated on d 50 at 400 MPa, the respective reductions in counts were 1.29, 1.98, 4.47, and > 5 log units. High-pressure treatments at 300 or 400 MPa on d 2 or 50 reduced significantly the counts of undesirable microorganisms, improving the microbiological quality and safety of La Serena cheese immediately after treatment and at the end of the ripening period.     

某油气田污染物的地下运移数值模拟

本文对美国某地一口油气开采井泄漏事故中的污染物在地下运移的过程进行了数值模拟。结果显示在考虑地下水与泄漏污染物的密度效应时,污染物渗透到地下后会污染当地的整个含水层,其滞留时间长达一年之久,对区域生态环境会产生负面影响;在忽略地下水与污染物的密度效应时,污染物主要滞留在地下浅部地区,主要对泄漏区附近的地表生态环境造成污染。因此,泄漏的污染物对当地或区域的生态环境具有长期的负面影响,油气资源的开采需在充分考虑水文地质条件的基础上进行污染防治和环境修复。     

2006-2008年广州市部分食品中违法添加物监测结果分析

目的了解广州市部分食品违法添加非食用物质现状。方法 2006—2008年对广州市市售水产品、保鲜食品、豆制品、粮食、蜜饯、蛋及蛋制品、乳及乳制品等进行食品污染物监测,同时进行部分非食用物质的监测。结果水产品、保鲜食品、豆制品中的甲醛检出率分别为21.21%、44.38%、1.14%,其中一份保鲜食品甲醛检出值最高达2 851.00 mg/kg;粮食、蜜饯、豆制品中的甲醛次硫酸氢钠(吊白块)均未检出;蛋及蛋制品中的苏丹红I～IV均未检出;乳及乳制品、含乳饮料中的三聚氰胺检出率分别为17.65%、11.11%,其中乳及乳制品三聚氰胺最高检出值达328.00 mg/kg。结论目前广州市市售部分食品仍存在违法添加非食用物质现象,应引起相关监管部门重视。     

空调系统新风和回风对室内空气品质的影响

分析了目前空调系统新风和回风对室内空气品质的影响，认为室内污染的不断增加是室内品质变坏的主要原因；新风的质量直接影响室内空气品质；回风是室内空气的二次污染源，导出了回风对室内空气污染的理论计算公式，文中认为新风率是20%能明显提高室内空气品质。     

Speciation of trace inorganic contaminants in corrosion scales and deposits formed in drinking water distribution systems

Sequential extractions utilizing the modified Tessier scheme (Krishnamurti et al., 1995) and measurements of soluble and particulate metal released from suspended solids were used in this study to determine the speciation and mobility of inorganic contaminants (As, Cr, V, U, Cd, Ni, and Mn) found in corrosion scales and particles mobilized during hydraulic flushing events. Arsenic, chromium and vanadium are primarily associated with the mobilization-resistant fraction that is resistant to all eluents used in this study and also bound in highly stable crystalline iron oxides. Very low concentrations of these elements were released in resuspension experiments. X-ray absorbance measurements demonstrated that arsenic in the sample with the highest As concentration was dominated by As(V) bound by iron oxides. Significant fractions of uranium and cadmium were associated with carbonate solids. Nickel and manganese were determined to be more mobile and significantly associated with organic fractions. This may indicate that biofilms and natural organic matter in the drinking water distributions systems play an important role in the accumulation and release of these inorganic contaminants.