Photodegradation of 4-tert octylphenol in aqueous solution promoted by Fe(III)

4-Tert-octylphenol (4-t-OP), a kind of endocrine-disrupting compounds, is widely distributed in natural water surroundings but can hardly be biodegraded. The advanced oxidation processes (AOPs) have been proved to be an efficient method to degrade 4-t-OP. In this study, the photodegradation of 4-t-OP in aqueous solution promoted by Fe(III) and the photooxidation mechanism were investigated. The ferric perchlorate was added into the aqueous solution for the production of hydroxyl radical. The efficiency of mineralization was monitored by total organic carbon analyzer, and photooxidation products were determined by high-performance liquid chromatography and liquid chromatography-mass spectrometer. 4-t-OP (2.4?×?10^?5 M) in aqueous solution was completely degraded after 45 min in the presence of Fe(III) (1.2?×?10^?3 M) under UV irradiation (λ?=?365 nm). The optimal pH was 3.5. Higher Fe(III) concentration or lower initial 4-t-OP concentration led to increased photodegradation efficiency of 4-t-OP. The reaction was almost completely inhibited in the presence of 2-propanol. About 70 % mineralization of the solution was obtained after 50 h. The photooxidation product was supposed to be 4-tert-octyl catechol. 4-t-OP in aqueous solution can be degraded in the presence of Fe(III) under the solar irradiation. The photoinduced degradation is due to the reaction with hydroxyl radicals. It shows that the 4-t-OP is mineralized by the inducement of Fe(III) aquacomplexes, which exposes to solar light. Therefore, the results would provide useful information for the potential application of the AOPs to remove 4-t-OP in water surroundings.     

Visual range trends in the Yangtze River Delta Region of China, 1981-2005

Visual range (VR) data from 1981 to 2005 were examined for 20 meteorological monitoring sites in the Yangtze River Delta Region of China. Cumulative percentile analysis was used to construct VR trend. The 25-yr average domain-average 50% VR was approximately 21.9 +/- 1.9 km. Domain-average 50% VR decreased from 1981 to 2005 with a trend of -2.41 km/decade. The worst 20% and 50% and best 20% VR and variation rates for the 20 sites were analyzed. The 50% VR of the town, county-level city, and prefecture-level city sites were 24.1, 21.5, and 19.4 km, respectively. The best 20% VR decreased fastest with a rate of -3.5 km/decade. Regional median VR decreased from the coastal sites to the inland sites. Ridit analysis and cumulative percentile were adopted to study the VR variation properties between economically developed areas (e.g., Nanjing and Hangzhou) and remote areas (e.g., Lvsi). The two analyses show that VR decreased in Nanjing and Hangzhou but remained constant in Lvsi from 1981 to 2005.     

基于细观结构的压实黄土抗剪特性试验研究∗

压实度是填方工程质量验收的主要控制项目之一,较高压实度对改善黄土力学性能效果显著。为全面系统分析压实对黄土抗剪特性的影响规律,更好地揭示较高压实度提高黄土抗剪能力的内在原因,利用室内三轴剪切试验和电镜扫描试验,基于 4 种不同压实度,对甘肃省临夏市北塬地区压实黄土的抗剪特性和细观结构进行了研究。研究表明：压实黄土应力—应变满足双曲线形式,较高压实度对提高黄土体抗剪强度和剪切模量作用显著;较高压实度通过改变土体颗粒之间的接触形式以改善黄土体抗剪特性,主要表现为压实黄土颗粒之间的接触形式随着压实度的增加由棱边接触、支架镶嵌向面接触逐渐过渡;较高压实度通过改变土体孔隙尺度特征和形态分布以改善土体抗剪特性,主要表现为随着压实度的增加孔隙分布范围内微、小孔隙的含量增加,中、大、特大孔隙含量减小,孔隙形状也相对变得圆滑。     

基于高阶动力格式的基底隔震结构地震响应分析∗

隔震支座在强烈地震作用下将产生复杂的动力响应,精确掌握地震响应行为及其规律是研发高质量隔震支座和进行隔震结构设计的基础。在进行结构地震响应分析,特别是非线性分析时,采用传统逐步积分方法以及低阶格式建立起的动力时程分析方法都难以达到高精度,而采用传统高阶时间积分算法则会出现计算过程繁琐,工作量大等情况。本文采用一种基于高阶动力格式的显式时间积分新式算法,应用于基底隔震结构的地震响应分析中。首先通过自由度凝聚缩减原理,建立设置隔震支座钢筋混凝土框架结构简化计算模型;同时采用隔震支座恢复力双切线本构模型构建基底隔震体系运动方程,并转化为状态方程;进而基于微分求积（DQ）原理编制高阶动力格式算法求解状态方程;最后分析一高层基底隔震结构,在高、中、低不同频率地震波下地震响应,验证该方法适用性。结果表明,①利用静态凝聚技术建立隔震结构模型,从而构建地震响应状态方程,是高阶动力分析方法实施的基础。②结构高阶动力分析方法仅通过矩阵乘法运算即可获得结构动力响应,可较好且高效地用于解决非线性地震响应分析问题。③将结构高阶动力分析方法应用于基底隔震结构,能获得隔震结构较为精确的分析结果。     

生死线上的一段经历

1964年,我作为实习生在国家测绘总局第二地形测量队工作期间,进入塔克拉玛干沙漠的西北腹地,参加完成了两幅1：10万地形图的高程控制测量及航空摄影野外调绘任务。这是令我终生难忘的一段踩在生死线上的经历。     

天然气净化厂管道泄漏H2S毒害后果影响因素数值分析

为定量评估高含硫天然气开敞空间泄漏过程中风速、风向、泄漏速度、泄漏方向对毒害后果的影响,以天然气净化厂管道泄漏为例,采用正交实验设计方法设计实验场景,基于CFD进行泄漏扩散仿真实验,以吸入剂量、毒害面积、最大毒害面积到达时间、毒害体积、最大毒害体积到达时间作为毒害效应指标,分析不同因素对毒害后果的影响,并提出后果控制建议。研究结果表明:采用CFD方法进行泄漏扩散仿真能够还原泄漏扩散过程;利用正交实验进行影响因素分析可以节省实验资源、获取准确结果;风向和风速对各后果指标均比较敏感,在天然气净化厂建设过程中应着重考虑风的影响。仿真与正交实验结合的方法能够有效评估毒害后果影响因素的敏感性,可为毒害气体泄漏风险防控提供指导。     

Applying Zonation Methods and Tabu Search to Improve the Ground‐Water Modeling1

Abstract: An optimization procedure combining zonation methods with the Tabu Search method is proposed to identify the spatial distribution of hydraulic conductivity field. Three zonation methods, Voronoi diagram (VD), multiplicatively weighted Voronoi diagram (MWVD), and pattern zonation are adopted for the parameterization purposes. With the consideration of the homogeneity and the heterogeneity, there are four spatial distributions of hydraulic conductivity designed to test whether the parameter structure can be successfully identified. The fitting residual error is first considered to determine an adequate number of zones without over parameterization. Then, the parameter uncertainty is evaluated the decision of the number of zones. The results indicate that the MWVD performs better than other two methods because the MWVD has better flexibility in describing the zonal boundaries with small number of decision variables.     

Comparison of EC and BC and evaluation of dust aerosol contribution to light absorption in Xi'an, China

The concentrations of EC, BC and dust aerosols were determined for atmospheric samples collected from an observation station in Xi'an, China. The results show that the averaged correlation coefficient between EC and BC was founded to be 0.72 with 0.81 (n = 49) in autumn, 0.70 (n = 112) in winter and 0.69 (n = 57) in spring, respectively. Absorption coefficients of dust aerosol were estimated to be 2.7 m² g⁻¹ in autumn and 4.4 m² g⁻¹ in winter. The comparison of absorption coefficients of dust aerosol with those of BC implies that BC is the principal light-absorbing aerosol over Xi'an atmosphere. By combining thermal analysis of elemental carbon and dust contents in the aerosol samples, however, the fraction of dust absorption to total light absorption is estimated to be 19% in autumn and 31% in winter, respectively.     

中央空调净化系统的改进措施

介绍了室内空气净化技术及其特点.针对中央空调系统的特点,提出了将活性炭吸附技术、TiO2光催化技术与静电除尘技术结合的静电活性炭-TiO2光催化复合技术,这一组合技术可能成为今后空调系统空气净化系统重要的改进措施.     

PAM的毒性作用及矿场防护措施

通过对油田现场施工情况的调研,论述了PAM及PAM类型的油田化学用剂在生产和应用过程中的毒性作用、毒性特点以及中毒后的临床表现,提出现场污染对环境的危害,同时为从事油田化学的技术人员提供了防护措施建议。