水溶液中苯酚电离形态表征及电渗析过程迁移特征

建立了紫外全波长扫描水溶液中苯酚电离形态的表征与定量分析方法,在此基础上,阐明了不同电离形态苯酚在电渗析过程中的迁移特征。结果表明：离子态、分子态和混合态（离子态和分子态的混合物）苯酚紫外全波长扫描在220～260 nm特征区间存在不同形状的特征峰,其浓度分别与特征波长258、236和236 nm处的吸光度有显著的线性定量关系;在电渗析过程中,离子态苯酚迁移特征为电渗迁移,分子态苯酚与酸协同迁移,混合态符合电离平衡控制迁移;离子态、分子态、混合态苯酚的迁移率分别为42%、4%和13%,在电渗析水处理过程中,有机污染物分子态和混合态的迁移也是重要的研究内容。     

智能视觉视角下DCS高危现场意外状况的识别方法研究

DCS分布式控制系统的高危现场意外状况仅仅以传感信号进行识别,很难保证识别过程的抗干扰性。为解决这一问题,提出基于智能视觉的DCS高危现场意外状况识别方法。采用计算机视觉特征方法采集DCS高危现场视觉图像,对视觉图像实施小波降噪预处理,提取降噪后DCS高危现场视觉图像边缘轮廓特征,根据该特征采用关键点帧扫描技术判断DCS高危现场关键点,完成DCS高危现场意外状况识别。实验结果表明,所提方法能够准确识别DCS高危现场的意外状况,具有效率高、抗干扰性强的优势。     

重构土壤垂直剖面重金属Cd赋存形态及影响因素

针对矿业废弃地高背景值-历史矿业源相叠加区下土壤重金属Cd污染问题,以西南地区某历史硫磺矿业废弃地重构土壤为研究对象,采集剖面土壤共30个样品,分析测试土壤样品中镉(Cd)、铬(Cr)、镍(Ni)、砷(As)和汞(Hg),利用电镜扫描-能谱分析(SEM-EDS)和重金属形态连续提取的BCR方法,分析不同土层厚度下Cd的赋存形式,运用风险评价编码法(RAC)和次生相与原生相分布比值法(RSP)对其进行有效性评价,以及对不同理化性质下Cd各形态的变化规律进行了初步探讨.结果表明,研究区5种重金属中Cd全量的富集系数最高,达4以上;通过形貌特征可以发现,样品中存在较多的次棱角状、棱角状颗粒,不同深度下的能谱特征显示结果相似,均含有Cd、Fe、S和As等元素,Cd元素是以类质同象形式存在;对Cd进行潜在风险评价,RAC结果显示为中等风险及以下,RSP结果主要为重度污染;重金属全量是影响Cd各形态含量分布的最主要因素,其次pH、有机质和CEC,对垂直深度的土壤Cd赋存形态也表现出不同程度的影响.该研究结果可为进一步了解Cd在剖面土壤的活性、迁移规律、生物毒性和赋存形式提供科学依据.     

Synthesis of novel CeO2-BiVO4/FAC composites with enhanced visible-light photocatalytic properties

To utilize visible light more effectively in photocatalytic reactions, a fly ash cenosphere （FAC）-supported CeO2-BiV04 （CeO2-BiVO4/FAC） composite photocatalyst was prepared by modified metalorganic decomposition and impregnation methods. The physical and photophysical properties of the composite have been characterized by X-ray diffraction （XRD）, scanning electron microscope （SEM） and energy dispersive X-ray spectroscopy （EDX）, X-ray photoelectron spectroscopy （XPS）, and UV-Visible diffuse reflectance spectra. The XRD patterns exhibited characteristic diffraction peaks of both BiVO4 and Ce02 crystalline phases. The XPS results showed that Ce was present as both Ce4＋ and Ce3＋ oxidation states in Ce02 and dispersed on the surface of BiV04 to constitute a p-n heterojunction composite. The absorption threshold of the CeO2-BiVO4/FAC composite shifted to a longer wavelength in the UV-Vis absorption spectrum compared to the pure Ce02 and pure BiV04. The composites exhibited enhanced photocatalytic activity for Methylene Blue （MB） degradation under visible light irradiation. It was found that the 7.5 wt.% CeO2-BiVO4/FAC composite showed the highest photocatalytic activity for MB dye wastewater treatment.     

全球乐活城市扫描

如果您有一颗年轻的心,关注时尚的生活方式,如果您像关心自己一样关心我们赖以生存的家园——地球的命运,您一定会注意到,有一种新的生活方式,正在越来越多的人的生活中被贯彻,这就是“乐活”。产生于西方发达国家的乐活,在国外发展得相当迅速。现在,从乐活原料供应商、乐活生产商、乐活商店、     

两种老化温度对某型双基推进剂的热分解性能的影响

目的探索某型双基推进剂在85℃和95℃条件下的热分解性能随老化时间的变化趋势。方法采用恒温加速老化试验,并对老化不同时间的样品进行热重分析(TG)和差示扫描(DSC)试验。结果计算了其两种老化温度条件下的动力学参数。结论某型双基推进剂性能良好,与老化时间相比,老化温度对其性能影响较大。     

Moisture distribution in sludges based on di erent testing methods

Moisture distributions in municipal sewage sludge, printing and dyeing sludge and paper mill sludge were experimentally studied based on four di erent methods, i.e., drying test, thermogravimetric-di erential thermal analysis (TG-DTA) test, thermogravimetricdi erential scanning calorimetry (TG-DSC) test and water activity test. The results indicated that the moistures in the mechanically dewatered sludges were interstitial water, surface water and bound water. The interstitial water accounted for more than 50% wet basis (wb) of the total moisture content. The bond strength of sludge moisture increased with decreasing moisture content, especially when the moisture content was lower than 50% wb. Furthermore, the comparison among the four di erent testing methods was presented. The drying test was advantaged by its ability to quantify free water, interstitial water, surface water and bound water; while TG-DSC test, TG-DTA test and water activity test were capable of determining the bond strength of moisture in sludge. It was found that the results from TG-DSC and TG-DTA test are more persuasive than water activity test.     

Novel synthetic approaches and TWC catalytic performance of flower-like Pt/CeO2

A novel Ultrasonic Assisted Membrane Reduction （UAMR）-hydrothermal method was used to prepare flower-like Pt/CeO2 catalysts. The texture, physical/chemical properties, and reducibility of the flower-like Pt/CeO2 catalysts were characterized by X-Ray Diffraction （XRD）, Scanning Electron Microscope （SEM）, Transmission Electron Microscope （TEM）, N2 adsorption, and hydrogen temperature programmed reduction （HE-TPR） techniques. The catalytic performance of the catalysts for treating automobile emission was studied relative to samples prepared by the conventional wetness impregnation method. The Pt/CeO2 catalysts fabricated by this novel method showed high specific surface area and metal dispersion, excellent three-way catalytic activity, and good thermal stability. The strong interaction between the Pt nanoparticles and CeO2 improved the thermal stability. The Ce4＋ ions were incorporated into the surfactant chains and the Pt nanoparticles were stabilized through an exchange reaction of the surface hydroxyl groups. The SEM results demonstrated that the Pt/CeO2 catalysts had a typical three-dimensional （3D） hierarchical porous struc- ture, which was favorable for surface reaction and enhanced the exposure degree of the Pt nanoparticles. In brief, the flower-like Pt/CeO2 catalysts prepared by UAMR-hydrothermal method exhibited a higher Pt metal dispersion, smaller particle size, better three-way catalytic activity, and improved thermal stability versus conven- tional materials.     

Mg(BH_4)_2和MgH_2对RDX热分解特性的影响

在黑索今(RDX)中加入具有高热值的金属氢化物(Mg(BH4)2和MgH2)有望提高RDX的爆炸性能,但同时给RDX的安全使用带来挑战。为了探索RDX与这2种金属氢化物的相容性与安定性,采用差示扫描量热法(DSC)研究Mg(BH4)2和MgH2对RDX热分解性能的影响,并由DSC得到的数据计算动力学参数,参照GJB770B—2005的方法分析这2种金属氢化物与RDX的相容性和安定性。结果表明,加入Mg(BH4)2使RDX的表观活化能从159.22 kJ/mol增加至180.27 kJ/mol,加入MgH2使RDX的表观活化能降低至133.69 kJ/mol;Mg(BH4)2与RDX的相容性为1级,MgH2与RDX的相容性为3级,加入Mg(BH4)2使RDX的安定性有所提高,加入MgH2降低了RDX的安定性。因此,在将MgH2作为RDX的高能添加剂以前,必须首先提高其与RDX的相容性以保证试验和存储过程的安全。     

电子显微技术研究生物膜特性

介绍了激光共聚焦扫描显微镜、扫描电子显微镜、环境扫描电子显微镜的工作原理、特点和功能,分析了电子显微技术在观察生物膜结构、形貌和微生物群落分布的优缺点.