Pressurized liquid extraction of six tetracyclines from agricultural soils

Veterinary antibiotics used in agriculture can be introduced into the environment through land application of animal manure, accumulating in soils and groundwaters and posing a significant risk to human health and animal well-being. As the analysis of tetracyclines in soil is challenging due to their strong interaction with soil minerals and organic carbon, the objective of this study was to develop a reliable and reproducible method for quantitative analysis of chlortetracycline and oxytetracycline, and their respective metabolites in soils. A method based on pressurized liquid extraction (PLE) with in-cell clean-up was developed for the extraction of chlortetracycline and oxytetracycline and four likely metabolites from a set of four soils. Optimized conditions included a cell size of 22?mL, soil loading of 5?g, pH of 8.0, methanol:water ratio of 3:1, 50?°C, and two cycles. Soil extracts were analysed by high-performance liquid chromatography (HPLC) coupled with ion trap mass spectrometry (MS). Recoveries of seven tetracyclines from soil ranged from 41% to 110%. The limits of detection for tetracyclines were 0.08–0.3 µg g^?1 soil, and intra- and inter-day variation ranged from 0.12–0.34%. The proposed PLE method is suitable for quantification of tetracyclines in agricultural soils at typical concentrations expected in contaminated environments.     

高效液相色谱-三重四级杆/复合线性离子阱质谱法测定饮用水中22种邻苯二甲酸酯

建立了一种同时测定饮用水中22种邻苯二甲酸酯(PAEs)的高效液相色谱-三重四级杆/复合线性离子阱质谱方法:饮用水样品经针头过滤器过滤,选用Biphenyl液相色谱柱进行分离,以含0.1%甲酸的水溶液和含0.1%甲酸的甲醇溶液为流动相,电离模式为电喷雾正离子,选用多反应监测触发增强子离子扫描模式进行检测。结果表明,22种PAEs的灵敏度良好,定量限为0.001～0.1 μg/L。配制浓度为0.1～100.0 μg/L的混标溶液进行进样分析,分析结果显示,22种PAEs在该范围内的线性关系良好,相关系数均大于0.995,方法的平均回收率为82.9%～108.9%,相对标准偏差为0.9%～11.2%。同时,使用增强子离子扫描谱图进行搜库匹配,定性准确性高。该方法适用于饮用水中PAEs的检测。     

基于ACF-AMDF的气井环空液面回波特征提取方法

为了精确有效地提取声波法检测气井环空液位的回波周期，在分析环空中测试波的传播特征及基音周期检测的基础上，提出1种基于检测信号短时自相关函数(ACF)及平均幅度差函数(AMDF)的液面回波周期提取方法；利用自主搭建的室内模拟实验系统开展了不同初始环空压力下环空液位检测实验；对检测信号进行中心削波处理并计算ACF/AMDF，提取出液面回波周期并与理论计算值对比分析；同时分析了现场环空液位检测信号，提取其回波周期。研究结果表明:提出的新方法能有效地用于提取环空液面回波周期；室内实验中，该方法最大误差绝对值为1.54%；该方法能够有效抑制液面回波信号中的随机噪声及接箍反射波等，处理后的信号曲线在回波周期处峰值更加突出、集中，而在其他位置更加平滑，提高了对液面回波周期特征的辨识能力。     

Morphological characteristics of flashing jet throughout superheated liquid release

Many release problems involve two-phase releases of hazardous materials of superheated liquids with high energy into the atmosphere. Such accidents are accompanied by violent phase transition and form catastrophic flashing jets. In this work, experimental and theoretical analyses were conducted to investigate dynamic characteristics of flashing jet morphology and their dependence on pressure-decay dynamics under different storage pressures, superheats, and nozzle diameters. Flashing jet morphology and angle throughout two-phase releases were captured by a high-speed camera, and the corresponding source pressure in the superheated liquid tank was measured simultaneously. Results show that three typical phases, expansion, stabilization, and decay, are characterized throughout two-phase release based on the evolution of flashing jet morphology. The jet initially expands gradually due to the enhancement of phase transition intensity, and then keeps stable when the intensity reaches its maximum, and terminally decays rapidly due to the depletion of superheated liquid. Phase transition intensity at the nozzle exit is mainly controlled by the pressure-decay dynamics. Bubbles nucleation inception sites gradually move upstream of the nozzle during the pressure decay process increasing the phase transition intensity. The increase of storage pressure, superheat and nozzle diameter promotes the mechanical and thermodynamic effects on the jet breakup. The significant increase of mechanical and thermodynamic effects effectively accelerates droplets evaporation and further affects flashing jet morphology.     

温州近海海域海水及滩涂沉积物中PFOS和PFOA污染特征分析

为了解温州近海海域全氟辛烷磺酸(PFOS)和全氟辛酸(PFOA)的污染状况和特征,采用固相萃取/高效液相串联质谱检测法分析了采自乐清湾、瓯江口、西湾、飞云江口及洞头半屏岛的近海海水和滩涂沉积物中PFOS和PFOA污染水平。结果显示,温州近海海水普遍存在PFOS和PFOA污染,其中,PFOS的浓度范围为<1.0～31.36 ng/L,中位浓度为2.29 ng/L;PFOA的浓度范围为<1.0～23.66 ng/L,中位浓度为5.29 ng/L。滩涂沉积物样品中PFOS和PFOA的浓度范围(干重)分别为(<1.0～11.91)×10-9(中位浓度为3.60×10-9)和(1.84～34.01)×10-9(中位浓度为6.83×10-9)。温州近海海水中PFOS和PFOA的污染水平明显高于香港沿岸、中国南海海水、韩国沿岸海水和近海珠江三角洲,与大连湾的海水相当,海岸滩涂沉积物中的PFOS和PFOA浓度远高于珠江和黄浦江沉积物中的浓度。     

平板显示器回收的新挑战

显示屏（监视器和电视机）经历了从阴极射线管到平板显示器技术的快速变化。截至目前为止,只有少量的平板显示器已记录在废物收集点。平板显示器的数量越来越多,在未来需要足够的用于回收的基础设施。本文旨在通过液晶显示屏幕的回收对经济影响的案例研究来提供数量、成分、回收利用技术和经验的基本数据。对于组件和材料也适用于其他类型的电子产品,如黑色金属和有色金属,印刷电路板或电缆,回收途径和技术是众所周知的和可用的。目前,液晶显示器（LCD）在欧洲不回收。处置时,例如,通过焚烧,有价值的材料,其成分是不再可用。例如：铟具有重要战略意义的应用,如,太阳能光伏作为一种稀缺资源。液晶显示器在欧洲具有回收基础设施,因此是有用的。     

散装液体危化品浮式码头金属软管失效原因分析及对策

介绍了金属软管在码头装卸船管路系统中的作用,并结合散装液体危化品浮式码头的实际,深入探讨了码头金属软管的失效原因,并提出了相应的防范措施,对提升金属软管的安全服役水平具有借鉴意义。     

某机载军用加固液晶显示器的振动试验

针对某型机载军用加固液晶显示器在随机振动试验条件下出现的故障,进行了故障定位和失效机理分析。根据分析结果对故障采取了相应的纠正措施(用硅橡胶减振器代替失效的异戊橡胶减振器),通过试验验证,证明该措施显著提高了该显示器的振动环境适应性。     

液氯泄露环境风险评价

文章以如东易昌化工有限公司为例,按照《建设项目环境风险评价导则》的要求,在对液氯的理化性质及危险性识别的基础上,分别进行了风险识别、伴生/次生危险性分析、源项分析等工作,确定了此次风险评价采用的相关标准,采用导则推荐的多烟团模式进行了事故发生后液氯泄露的环境风险预测和评价,得出了不利气象条件下的事故风险影响范围,求得了最大风险值,并从氯气瓶库及供氯站设置、生产过程等方面提出了相关的风险管理措施。     

乌海市焦炉煤气综合利用技术典型案例分析

介绍目前乌海市在建和已建成的焦化生产企业产能和焦炉煤气综合利用现状,以及当地政府在发展焦化行业的同时开展循环经济、节能减排的工作思路。以当地新建的焦炉煤气制取液化天然气项目为例,论述了该项目焦炉煤气原料保证、液化天然气产能等技术方向及主要工艺流程,对比分析各装置工艺技术路线、主要设备工作原理、设备能力确定的具体方案,讨论评估了焦炉煤气制液化天然气项目各装置采用的技术优势及项目实施后带来的环境、经济和社会效果。