杭州湾南岸滩涂沉积物中HCHs与DDTs污染特征分析

摘 要：目的 了解六六六（hexachlorocyclohexanes,HCHs）与滴滴涕(dichloro diphenyl trichloroethanes,DDTs)在杭州湾南岸滩涂沉积物中的污染现状。方法 于2018年4月，采集杭州湾南岸地区4个采样点不同深度（0~80 cm）滩涂沉积物，利用气相色谱-串联质谱法（gas chromatography tandem mass spectrometry, GC-MS/MS）测定了该区域中HCHs与DDTs的含量，对其分布规律进行分析，使用共识沉积物质量基准法对其生态学风险进行了评估。结果 所有样品中均检出，HCHs与DDTs含量分别为4.20~6.24 μg/kg与3.37~4.73 μg/kg，主要以β-HCH、δ-HCH以及DDE为主，其污染主要来源于历史性工业品，整体污染处于较低水平；20.3%的沉积物样品中DDEs含量以及28.1%的样品DDTs总量介于阈值效应浓度(threshold concentration, TECs) 和可能效应浓度(probable effect concentration, PECs)之间。结论 杭州湾南岸沉积物中HCHs与DDTs的污染处于较低水平，具有较小的生态学风险。     

Balancing the strength and ductility of Mg-6Zn-0.2Ca alloy via sub-rapid solidification combined with hard-plate rolling

In this study,we successfully prepared a Mg-6Zn-0.2Ca alloy by utilizing sub-rapid solidification (SRS)combined with hard-plate rolling (HPR),whose elongation-to-failure increases from ～17 ％ to ～23 ％without sacrificing tensile strength (～290 MPa) compared with its counterpart processed via conven-tional solidification (CS) followed by HPR.Notably,both samples feature a similar refined grain structure with an average grain size of ～2.1 and ～2.5 μm,respectively.However,the high cooling rate of ～ 150 K/s introduced by SRS modified both the size and morphology of Ca2Mg6Zn3 eutectic phase in comparison to those coarse ones under CS condition.By subsequent HPR,the Ca2Mg6Zn3 phase was further refined and dispersed uniformly by severe fragmentation.Specially,the achieved supersaturation containing exces-sive Ca solute atoms due to high cooling rate was maintained in the SRS-HPR condition.The mechanisms that govern the high ductility of the SRS-HPR sample could be ascribed to following reasons.First,refined Ca2Mg6Zn3 eutectic phase could effectively alleviate or avoid the crack initiation.Furthermore,excessive Ca solute atoms in α-Mg matrix result in the yield point phenomenon and enhanced strain-hardening ability during tension.The findings proposed a short-processed strategy towards superior performance of Mg-6Zn-0.2Ca alloy for industrial applications.     

河南某硫酸烧渣制备氯化铁铵的试验研究

以河南某硫酸烧渣为原料, 采用盐酸浸出-浓缩净化-氯化铵诱导-冷却结晶工艺制备优级纯氯化铁铵晶体。实验所得最佳工艺条件为: 盐酸溶液浓度40%、液固比8∶1、浸出温度85 ℃、浸出时间40 min、氯化铵过量系数0.9, 此条件下原料中铁浸出率为91.43%, 所制备的氯化铁铵纯度达到99.85%。     

飞机机械成品试验信息管理系统设计与应用

分析了航空企业飞机机械成品试验的现状,结合企业信息化管理的发展趋势,对飞机机械成品试验的流程进行梳理,基于ASP.NET技术研究开发了某企业飞机机械成品试验数据收集及信息管理系统,以实现飞机机械成品试验的流程化、数字化及显性化管理,避免因试验台管理不善造成的质量问题,实时掌握试验台状态,促进形成自主管理模式。     

脉冲偏压对TiAlCN薄膜结构与力学性能的影响

利用多弧离子镀-磁控溅射复合技术通过改变脉冲偏压在Si片与SS304基体表面制备了TiAlCN薄膜,研究了不同脉冲偏压对薄膜结构和力学性能的影响。薄膜成分、表面形貌、相结构及力学性能分别利用能量弥散X射线谱(EDS)、扫描电镜(SEM)、X射线衍射(XRD)和纳米压痕仪等设备进行表征。结果表明,随着脉冲负偏压的增加,薄膜中Ti元素的含量先减小后增大,而Al元素有相反的变化趋势。适当增大脉冲偏压,薄膜表面颗粒、凹坑等缺陷得到明显改善。物相分析表明TiAlCN薄膜主要由(Ti,Al)(C,N)相,Ti4N3-x相和Ti3Al相组成。薄膜平均硬度与弹性模量随脉冲负偏压的增加先增大后减小,在负偏压-200 V时达到最大值分别为36.8 GPa和410 GPa。     

Mg2+-CO32--Gly--H2O体系热力学分析

根据碳酸镁在氨基乙酸盐(Gly~--H_2O)体系中的溶解热力学平衡方程建立了其溶解热力学模型,分别分析了298K时体系中镁离子总浓度、游离镁离子浓度、游离氨基乙酸根离子浓度、游离碳酸根离子浓度、镁物种分布以及氨基乙酸根物种分布热力学结果。结果表明,在酸性氨基乙酸盐体系中(pH值7),碳酸镁溶解以酸溶作用为主,碳酸镁可以大量溶于酸性氨基乙酸盐溶液中;在碱性氨基乙酸盐体系中(7pH值14),碳酸镁溶解以氨基乙酸根离子与镁离子配合作用为主,由于氨基乙酸根离子与镁离子配合能力较弱,碳酸镁不可能溶于碱性氨基乙酸盐溶液中。     

A Cloud-Based Wireless Radio Intensity Recording System

Wireless Personal Communications - In recent years, many wireless communication services have become indispensable for our daily life, such as voice telephoning and the internet surfing. However,...