Degradation of acrylonitrile–ammonium itaconate copolymers

Acrylonitrile–ammonium itaconate copolymers were prepared by H₂O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry results of the degradation of acrylonitrile–ammonium itaconate copolymers in air are presented. The apparent activation energy of degradation of the copolymer was calculated using the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. Increasing the dimethyl formamide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of acrylonitrile–ammonium itaconate copolymer. The value of the degradation apparent activation energy of the copolymer synthesized in dimethyl formamide solvent increases up to 168.3 kJ mol^?1. The apparent activation energy decreases quickly along with an increase in ammonium itaconate concentration, and this change becomes less prominent as the weight ratio of ammonium itaconate/acrylonitrile goes beyond 6/94, ΔE_a = 89.4 ± 2.0 kJ mol^?1. The apparent activation energy shows a trend of increase with increasing copolymerization temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1708–1711, 2005     

Treatment of Groundwater Contaminated with 1,4-Dioxane,Tetrahydrofuran, and Chlorinated Volatile Organic Compounds Using Advanced Oxidation Processes

Ozonation and four types of advanced oxidation processes, including O₃/H₂O₂, O₃/UV, O₃/H₂O₂/UV, and UV/H₂O₂, were evaluated for the treatment of contaminated groundwater at a Superfund site in Simpsonville, South Carolina using bench-scale, batch ozone and UV apparatuses. Although the contaminants of concern were 1,4-dioxane, 1,1-dichloroethene, and trichloroethene, several other chlorinated organics as well as tetrahydrofuran were found in the groundwater samples. The O₃/H₂O₂ treatment with O₃ and H₂O₂ doses of 6 and 1.5 mg/L, respectively, and the UV/H₂O₂ treatment with UV and H₂O₂ doses of 1,000 mJ/cm and 20 mg/L, respectively, were sufficient to degrade 200 µg/L of 1,4-dioxane, 110 µg/L of 1,1-dichloroethene, and 10 µg/L of trichloroethene below their performance standards of 10, 7, and 4 µg/L, respectively. Due to a high bromide concentration (0.35 mg/L) in the groundwater sample, bromate formation was found to be significant in ozone-based treatment, including O₃/H₂O₂.     

Effect of Winter Low Temperature on Physiological and Biochemical Indexes of Desert Plants Yucca brevifolia Seedlings

利用2年生约书亚树(Yucca brevifolia)幼苗进行低温越冬试验,对冻害程度及其生理生化指标进行测定分析.结果表明:随着冻害程度的加重,质膜透性、游离脯氨酸及可溶性糖含量逐渐升高,叶绿素含量SPAD值逐渐降低,其中覆土容器苗的冻害程度最为严重,其质膜透性、游离脯氨酸及可溶性糖含量分别达到了74.869 8%,3.558 3 mg/g和174.886 4 mg/g,SPAD值仅为28.566 7,与对照相比差异均达到极显著水平;林下约书亚树幼苗的MDA含量最高,达到了5.511 5 mmol/g,且与其他处理间存在极显著差异.结合越冬后约书亚树幼苗的冻窖指数及生理生化指标,利用主成分分析法综合评价3种越冬方式下约书亚树幼苗的表现为地窖内防寒越冬效果最好,室外覆土容器苗和林下栽植幼苗冻伤较严重.     

非等温蠕变时效对Al-Zn-Mg-Cu合金力学性能和耐腐蚀性能的影响

研究了非等温蠕变时效处理中升温速率和峰值温度对Al-Zn-Mg-Cu合金回弹性能、力学性能和耐腐蚀性能的影响。通过透射电镜分析了合金的析出行为和时效强化机理。结果表明：随着加热速率的降低和峰值温度的升高,合金的回弹率降低;晶内析出相的尺寸增大,而体积分数先增大后减小;晶界析出相逐渐变得不连续,无析出区扩大。经非等温蠕变时效（20℃/h,180℃）处理后的合金主要析出相为致密的η’相,晶界析出相不连续,无析出区的宽度约为44.2 nm。非等温蠕变时效（20℃/h,180℃）处理的合金力学性能和耐腐蚀性能均优于常见的等温蠕变时效（120℃,24 h）处理的合金,并且时效时间缩短了67%。     

Experimental definition and its significance on the minimum safe distance of blown sand between the proposed Qinghai-Tibet Expressway and the existing Qinghai-Tibet Railway

Science China Technological Sciences - The Qinghai-Tibet Expressway is a major strategic project planned by China that will be built along the Qinghai-Tibet Engineering Corridor. At present,...     

历史保护建筑的生态节能更新——同济大学文远楼改造工程

具有包豪斯建筑风格的同济大学文远楼是我国现代保护建筑的典范之一,2005年同济大学与德国节能技术专家合作,运用当代最新的建筑节能技术,建立一套综合节能技术系统,为我国保护建筑的节能更新改造提供了范例,本文重点介绍一些改造技术的实践情况。     

用γ能谱分析法作元件破损实时监测中的影响因素

本文对用γ能谱分析法反应堆燃料元件破损实时监测中的影响因素进行了分析，干扰监测的主要因素为由＾１９Ｏ和＾１６Ｎ产生的γ光子，活化腐蚀产物的γ辐射，湮灭辐射以及ＮａＩ探测器周围铅屏蔽上由高能γ产生的ＰｂＸ射线，在一座压水反应堆的两次故障排除工作中，作者利用上述分析结果，对实时监测中产生的异常情况作了正确分析，并正确报判断了反应堆内元件的安全性。     

最优模糊控制的两种设计方法

本文基于二次型性能指标，给出了采用梯度法和遗传算法的模糊控制规则优化方法，并比较了它们的优缺点。仿真结果表明，这两种方法对未知系统的模糊规则优化具有明显的应用价值。     

数字城市规划研讨厅数据组织体系的构建方法探究

数据组织是数字城市规划研讨厅的基础,该文从规划研讨厅的可持续发展出发,分析了城市规划数据的基础内容,探讨了数据体系构建的理论和方法,最终形成了数字城市规划研讨厅数据体系的基本框架,并重点阐述其特性.     

常用的几种低热粘结温度柔软型PP短纤维的剖析与研讨

应用ＤＳＣ,ＷＡＸＤ,ＳＥＭ和红外光谱等技术对热轧法生产卫生用薄型非织造布的几种常用纤维进行了剖析,并对其形态结构、热性能、力学性能、含油率、含湿率、抗静电性和渗水性等进行了比较和研讨。结果表明：低热粘结温度ＰＰ短纤维多为细旦、低强、高伸度、低起始熔融温度和低序态,且适宜的含油率、含湿率和表面比电阻可保证梳理性好,成网均匀