钛金属材料干摩擦磨损特性研究

目的研究钛金属材料干摩擦磨损失效机制。方法选用TA2工业纯钛和TC4钛合金材料,采用CETR UMT-3多功能摩擦磨损测试仪进行往复摩擦磨损试验,采集摩擦系数曲线,计算摩擦系数均值,从动态和静态分析钛金属材料的摩擦特性。采用Micromet-6030型自动显微硬度计测量样品材料表面硬度值,通过表面硬度分析耐磨损性能。采用Nova Nano SEM 650场发射扫描电镜并配置能谱仪对磨损表面和磨屑进行微观形貌观察和元素成分计量分析,从微观角度分析钛金属材料的磨损机理。采用Olympus Lext OLS3000-R型激光共聚焦显微镜测量磨损体积和轮廓,并观察磨损表面的三维形貌。结果频率对钛金属材料的摩擦系数和耐磨损性能影响较大,随着频率的加快,摩擦系数增大,数据跃变幅度增大,磨损体积随之增大。载荷对摩擦系数影响相对较小,随着载荷增大,在摩擦初期,摩擦系数有下降交汇趋势;摩擦后期,摩擦系数才明显上升,载荷与磨损体积之间基本呈线性增长关系。钛金属材料的磨痕呈现为\"擦后型,随着载荷的增大和频率的加快,磨损体积轮廓呈现出加深变宽的趋势。TC4的表面硬度约为359.2 HV,TA2的表面硬度约为247.8 HV,前者比后者高出约111.4 HV。在相同试验条件下进行干摩擦磨损试验,TA2的磨损体积约为TC4的2.5倍,TA2的耐磨损性能相对较差。TA2的磨屑为细小的颗粒状磨屑,磨损表面存在严重的剥层脱落特征;TC4的磨屑粒径大小不一,在低频低载状态下,磨损表面有犁沟痕迹,不存在明显的剥落坑。随着载荷和频率的增大,摩擦表面层出现裂纹和碎化剥落现象。结论 TA2的磨损机制主要是剥层磨损和磨粒磨损。在低频低载状态下,TC4的磨损机制主要为磨粒磨损和氧化磨损,随着载荷和频率的升高,在瞬时闪现温度和载荷的作用下,其磨损机制主要为粘着磨损和剥层磨损。     

活性炭对海岛纤维开纤剥离废水中回收TA吸附效果的研究

采用活性炭吸附做为海岛纤维开纤剥离废水直接酸析前的预处理,净化废水,提高回收TA的品质。对工艺条件进行了系统研究。以酸值、光密度和灰分为考核指标,设计正交实验,得出因素影响水平为:活性炭投入量>吸附温度>吸附时间>振荡速度,分析各因素对回收TA性能的影响趋势,建立回归方程。同时建立活性炭对废水中COD,TA的吸附理论模型(Langinulr和Freundlich等温方程),结果表明Freundlich等温方程能较好反应此吸附过程。     

Combination of in vitro bioassays for the determination of cytotoxic and genotoxic potential of wastewater, surface water and drinking water samples

In this study we evaluated genotoxicity and cytotoxicity of native samples of wastewaters (15 samples), surface waters (28 samples) and potable waters (8 samples) with the SOS/umuC assay with Salmonella typhimurium TA1535/pSK1002 and MTT assay with human hepatoma HepG2 cells. The genotoxicity of selected samples was confirmed with the comet assay with HepG2 cells. In the SOS/umuC assay 13 out of the 51 samples were genotoxic: two effluent samples from chemical industry; one sample of wastewater treatment plant effluent; two hospital wastewater samples; three river water samples and four lake water samples. Six samples were cytotoxic for HepG2 cells: both effluent samples of chemical industry, two wastewater treatment plant effluent samples, and two river water samples, however, only the chemical industry effluent samples were genotoxic and cytotoxic, indicating that different contaminants are responsible for genotoxic and toxic effects. Comparing genotoxicity of river and lake water samples with the chemical analytical data of the presence of the residues of pharmaceutical and personal care products (non-steroidal anti-inflammatory drugs, UV filters and disinfectants) in these samples, indicated that the presence of UV filters might be linked to the genotoxicity of these samples. The results showed that the application of the bacterial SOS/umuC assay and mammalian cell assays (MTT and comet assay) with HepG2 cells was suitably sensitive combination of assays to monitor genotoxicity and cytotoxicity of native samples of wastewaters and surface waters. With this study we also confirmed that the toxicity/genotoxicity bioassays should be an integral tool in the evaluation of toxicity of complex wastewaters before the release into environment, as well as for the monitoring of surface water quality, providing data useful in risk assessment.     

A study of 2,4,6-trinitrotoluene inhibition of benzo[a]pyrene uptake and activation in a microbial mutagenicity assay

A number of in vitro and in vivo studies have determined that binary and complex mixtures may interact to produce a toxicity that could not be predicted based on the individual chemicals. The present study was conducted with a binary mixture of model compounds to investigate possible interactions affecting their mutagenicity. The compounds included Benzo[a]pyrene (BAP), a polycyclic aromatic hydrocarbon that is an indirect-acting mutagen of great environmental concern, and 2,4,6-Trinitrotoluene (TNT), a nitro-aromatic compound that is a direct-acting mutagen frequently found as a soil contaminant at munitions sites. This study indicated that a binary mixture of BAP and TNT failed to induce the positive mutagenic response in Salmonella typhimurium strain TA98 characteristic of either compound alone. Spectrofluorometric analysis of BAP, and kinetic analyses of ³HBAP uptake in the presence or absence of TNT using TA98 cells that were treated or untreated with activated rat liver microsomes were performed. In cells preloaded with BAP, cellular BAP fluorescence was rapidly suppressed in the presence of TNT. Mass spectroscopy of BAP and TNT mixtures revealed a number of products, believed to be the result of complexation and nitration, that may account for the antagonistic action of TNT on BAP-induced mutagenicity in TA98 cells. Further, kinetic studies indicated that TNT inhibited the incorporation of BAP into cells.     

Correlations between mutagenic activity of organic extracts of airborne particulate matter, NOx and sulphur dioxide in southern Germany: results of a two-year study

Goals, Scope and Background Among other substances, sulphur dioxide (SO2), nitric oxide (NO) and nitrogen dioxide (NO2) are parameters which are routinely measured to describe basic air quality. Organic extracts of airborne particulate matter contain mutagenic chemical compounds of different origins. The aim of the study was to find correlations between routine monitoring data and mutagenic activity of organic extracts of simultaneously drawn samples.Methods Specimens were collected over a period of two years at 8 sampling sites in south-west Germany. Simultaneously, concentrations of NO, NO2, and SO2 were measured on-line within the framework of the official air monitoring network of Baden-Württemberg, Germany. Dust samples were collected for biotesting using high volume air samplers equipped with glass fibre filters. After sampling was completed, filters were extracted and samples were prepared for biological testing. Mutagenic activity was tested by means of the plate incorporation assay (Ames test) using S. typhimurium TA98 and TA100 tester strains. During the first year of the study, all tests have been performed with and without metabolic activation. Additionally, a series of tests has been performed in parallel with TA98 and TA98NR.Results and Discussion Comparison of Ames test data obtained with and without metabolic activation indicates no statistically significant difference between both methods. Therefore, during the second year of the study, all tests have been performed without metabolic activation. Average yearly activities at the sampling sites were between 1 und 27 Revertants per m³ (Rev/m³). High activities were preferably found at congested sites (Karlsruhe, up to 95 Rev/m³). However, peak values of over 100 Rev/m³ were found in other places where pollution by traffic is significantly lower. The reason for these high level values is not evident. Tests performed using TA98NR tester strain indicate a significant share (average 31%) of compounds requiring activation by nitroreductase for mutagenic activity. Average mutagenic activity can be correlated to routine monitoring parameters. Comparison of averaged data for particular sampling sites indicates significant correlation between nitric oxide and mutagenic activity in TA98 (r²=0.90), while correlation between nitrogen dioxide (0.84) or sulphur dioxide (0.52) and mutagenic activity is weaker. For TA100, correlations are generally weaker than for TA98. Comparison of data for mutagenic activity and routine monitoring data of distant sites being sampled simultaneously shows parallel behaviour.Conclusions Results from this study show that mutagenic activity can be compared to seasonal and local variations of gaseous indicator air pollutants. Tester strain TA98 generally shows the best correlations. Although pollution by particle-bound mutagenic substances is significantly higher during the cold season than during summer on average, mutagenic activity of airborne dust is not a continuous effect. During winter, peak levels as well as low pollution periods can occur. Even during winter time mutagenic activity can reach very low levels typical for summertime. Comparison of results for distant sampling sites where samples have been collected simultaneously indicate that “classical” indicators of air pollution and bacterial mutagenicity of organic extracts from airborne particulate matter are influenced by connected effects. Seasonal trend of mutagenic activity, in particular, is similar to the concentrations of nitrogen oxide. NO is a strong indicator for vehicle exhaust gases. It is concluded that the average mutagenic activity at particular sites can be estimated using NO concentrations as an indicator.     

色纤碱减量废水中对苯二甲酸的回收精制研究

文章研究了酸析法从带色碱减量废水中回收对苯二甲酸(TA)过程,并且通过废水预处理进行TA的简单精制。结果表明,这种处理方法不但能大幅度降低碱减量废水的COD值,而且可以获得高纯度对苯二甲酸。另外,文章还对回收得到的对苯二甲酸的用途进行了简单分析。     

海洋大气对TA15钛合金应力腐蚀影响研究

采用恒位移WOL试样测定KISCC的原理对已在海洋平台户外和海水飞溅区暴露2a的TA15钛合金样及原始TA15钛合金样进行了应力腐蚀行为研究。探讨了TA15钛合金预制裂纹的条件,并用裂纹终止法测量应力腐蚀临界应力场强度因子,确立了应力场强度因子KISCC与裂纹瞬时扩展速率da1dt-C间的联系,并绘制了lg（da／dt）-K1曲线。通过扫描电镜对试件断面进行了分析,对其断裂特征进行了描述。     

二次热解吸直接进样气相色谱法测定空气中苯系物

文章建立了空气中苯系物的分析方法,方法用Tenax TA吸附管吸附空气中苯系物,二次热解吸直接进毛细管气相色谱分析。该方法定性、定量准确,线性响应良好,回归方程的线性相关系数大于0．9991,相对标准偏差在2．1％～5．3％之间,加标回收率大于92％,具有良好的重现性。测定干扰小,检测灵敏度高,当采样体积1L时,平均解吸率在95％以上,苯系物的最低检出浓度可达0．5ug／m^3。本方法适合测定空气中低浓度的苯系物。     

硝酸盐对降解对苯二甲酸厌氧污泥驯化的影响

硝酸盐在通过反硝化作用加速菌体生长的同时,对污泥中降解ＴＡ菌群的形成有进一步的诱导作用。经过６周的驯化其对ＴＡ的比降能力达到１８．７５ｍｇ／（ｄＶＳＳ．ｄ）,而对照组为１０．２８ｍｇ／（ｇＶＳＳ．ｄ）研究结果还显示,经过２－３周可以完成从反硝化作用到产甲烷作用的转化。