微波消解测定土壤重金属体系的研究

对微波消解测定土壤金属元素的标准曲线绘制方式进行了研究。以铜元素为例,分别使用金属标准使用液和土壤标准样品消解液进行标准曲线的绘制,结果表明:在测定土壤样品时,直接用标准使用液绘制标准曲线,土壤带标测定结果都偏低,测定误差10%以上;用土壤标准样品消解液作为标准曲线进行带标测定,土壤带标测定结果在标准范围内。本方法避免了土壤样品因消解不完全而产生的误差,能够提高土壤金属样品分析的准确率。     

超声波消解测定土壤中锑、铍的方法

对土壤样品先进行超声波消解,再使用电感耦合等离子体原子发射光谱(ICP-AES)对锑、铍元素进行测定;样品加入硝酸、氢氟酸经超声波消解,再高氯酸冒烟飞除硅。在5%的盐酸介质中,于优化后的仪器条件下测定锑、铍元素。本方法方法回收率在93.0%~102.5%之间,方法标准偏差小于3.0%,该方法流程简便,分析快速,结果较准确。     

氟化铵辅助消解结合ICP-MS测定滤棒中的7种元素含量

采用氟化铵辅助微波消解联合电感耦合等离子体质谱法测定卷烟滤棒中铬、镍、砷、硒、镉、汞和铅7种元素含量。以氟化铵/硝酸作为消解体系消解样品,考察了氟化铵用量、消解温度、消解时间对滤棒样品消解效果的影响。结果表明,最佳前处理条件为0.2 g滤棒样品在6 mL 60%硝酸和0.75 mL(12.66 mol/L)氟化铵溶液中消解,消解温度为175℃,恒温保持20 min。对不同样品进行测定,7种元素检出限在0.007～0.044 mg/kg之间,样品的加标回收率为92.50%～108.36%,相对标准偏差为1.71%～5.65%。该方法与传统方法同时测定滤棒样品7种元素含量相比较无显著性差异(P0.05)。方法使用试剂种类少,更加绿色环保,避免了直接使用大量氢氟酸带来的安全隐患,且能快速、准确的测定滤棒中7种元素的残留量。     

不同消解方法在测定样品中重金属含量的应用

介绍了在测定土壤样品、油脂类样品、植物类样品中重金属含量的多种消解方法,主要包括微波消解法、湿法消解、干灰化法三种方法。通过比较三种方法的优缺点,微波消解法因其快速、准确的特点成为实验中消解样品的最优选择。但在实验时,也应考虑待测样品及元素的性质来确定使用的消解方法。     

土壤中重金属消解方法的对比研究

利用标准样品对比研究了3种不同消解方法测定土壤中重金属元素的差异。将(1)电热板消解(2)微波消解(3)全自动消解仪快速消解预处理方法进行分析比较,分析多种消解方法的优点和缺点,推荐实用、准确、高效、方便快捷的消解预处理方法。并对多种消解样品分别测定铜、锌、铅、镉、铬、镍重金属元素含量验证推荐消解方法的预处理效率。结果表明,电热板加热消解将土壤样品彻底消解,但消解时间略长,消解过程敞开系统,对操作人员造成危害;微波消解密封消解避免了一些易挥发组分的损失,并且外源性污染少;快速消解方法速度较快,但消解不完全。     

ICP-MS在食品安全检测中的应用研究

砷是影响食品安全的主要元素之一,因此对食品中砷元素的检测对于保障食品安全有非常重要的作用。在文章的研究中,主要采用ICP-MS对大米、小麦中的砷元素含量进行检测。对大米、小麦中砷的提取方法如下:采用高速匀浆机将大米样品磨碎后,使用微波消解仪高压密闭消解法对大米、小麦样品进行消解,并通过甲醇/水提取进行砷,采用CCT碰撞反应池模式来消除砷总量检测时杂质元素的干扰,利用高效液相色谱仪来确定食品中砷的元素形态。     

电热板消解ICP测定尾矿渣中的锌铅锰镉

文章采用电热板对尾矿渣进行消解方法的摸索,通过样品消解的完全性与时效性对消解方法的评价,得出尾矿渣的消解方法,采用王水-硝酸-高氯酸体系能够完全消解尾矿渣。选择锌铅锰镉元素作为分析目标元素,完全消解的尾矿溶液采用ICP-OES分析测试,为尾矿渣的进一步研究提供可靠数据分析。     

方差分析在烟草金属元素测定中的应用

采用干灰化法、湿法灰化、微波消解3种不同的样品前处理方法处理同一烟草样品,用火焰原子吸收光谱法测定K、Ca、Mg、Cu、Zn元素含量。对每一个元素的测定结果进行方差分析,结果表明,在显著性水平α=0.05水平上,使用3种不同的样品前处理方法采用火焰原子吸收光谱法测定烟草中K、Ca、Mg、Cu、Zn 5个元素含量无明显差异。     

电热板-ICP-AES法分析土壤中总铬的方法优化

在测定土壤中总铬的含量时,结果往往低于比标准值。本实验通过改进消解方法,解决了在消解过程中Cr元素的损失问题。通过在消解过程同步进行样品加标实验,并进行加标校正,解决了基体效应对样品测试结果的影响。结果表明,改进后的方法中,所有标准土壤样品分析结果均在保证值范围内,其变异系数处于1.0%～1.4%,该方法适合用于土壤中总铬的测定。     

微波消解-电感耦合等离子体发射光谱法准确测定原油中S、Ni和V

开展了微波消解结合电感耦合等离子体发射光谱(ICP-OES)分析测量原油中有害元素(S、Ni和V)的方法研究。通过优化样品微波消解前处理条件(样品量、酸体系、消解程序等),实现了4种不同来源、有害元素含量不同的原油样品的完全消解。ICP-OES测量结果表明:原油中Ni和V元素的检测限为0.34～0.45μg/kg、定量限为1.14～1.51μg/kg,原油中S元素的检测限和定量限分别为2.72、9.07μg/kg,原油中3种元素测量重复性均小于2.8%。燃料油和原油有证标准物质分析测量结果表明,3种元素的回收率均为98%～104%,说明了所建立微波消解结合ICP-OES方法的准确可靠性。所建立的原油中S、Ni和V元素的准确测量方法,能够用于原油样品中有害元素的质量控制以及相应标准物质的定值。     

Ageing resistance of SiBCN ceramics

Amorphous SiBCN alloys are known – depending on the elemental composition – for their thermal stability and high-temperature (up to 1500 °C) oxidation resistance, hardness, optical transparency or electrical and/or thermal conductivity. The paper reports ageing of SiBCN ceramics prepared in the form of thin films in a wide range of elemental compositions and preparation conditions. I focus on the room-temperature oxidation resistance, expressed in terms of the thickness and properties of the surface oxide layer 12 years since the deposition. I identify which compositions exhibit perfect long-time room-temperature oxidation resistance (this includes those, but not only those, which exhibit short-time high-temperature oxidation resistance) and which do not. For the latter I discuss the complex relationships between the characteristics of the surface oxide layer, the elemental composition of the films and the ion bombardment during the film growth. The results are important for tailoring long-lifetime ceramics combining the aforementioned functional properties.     

Synthesis and Study of a Polypyrrole–Aluminum Oxide Nanocomposite Film on an Aluminum Surface

Using the method of electrochemical anodization, aluminum oxide porous films are obtained in a sulfuric acid solution. The morphology of the aluminum oxide surface is studied by the method of scanning electron microscopy. The high-quality elemental analysis of the initial and oxidized Al films is performed using the method of electron microprobe analysis. A protective composite polypyrrole-aluminum oxide film is produced on the aluminum surface on top of a porous aluminum oxide film in the galvanostatic oxidation mode by the electrochemical synthesis method. The properties of the polypyrrole–aluminum oxide composite film are studied by the methods of voltammetry, as well as impedance and FTIR spectroscopy.     

A study on the effect of compositing silver oxide nanoparticles by carbon on the ‎electrochemical behavior and electronic properties of zinc‐silver oxide batteries ‎

In this study, the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide batteries have been investigated. For this purpose, firstly four silver oxide electrodes containing 5, 10, 15, and 20 wt% carbon powder were produced by powder metallurgy method. For the next step, all four silver oxide electrodes were sintered at 500°C for 10 minutes. Afterward and in order to investigate the microstructure, phase and elemental analysis of the electrodes were carried out using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X‐ray Diffraction (XRD), and Energy Dispersive Spectroscopy (EDS), respectively. Moreover, in order to investigate the effect of compositing silver oxide nanoparticles by carbon on the electrochemical behavior and electronic properties of zinc‐silver oxide, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and electric discharge test in 1.4 wt%KOH electrolyte were carried out respectively. The microstructural observations revealed that increasing carbon content in the silver oxide electrodes results in increasing the apparent porosities in these electrodes. Investigating the phase and elemental analysis results showed that by increasing the content of carbon in the silver oxide electrode, the amount of Ag₂O and AgO phases in this electrode reduces and also the extent of pure silver formation increases. Investigations on the results of electrochemical tests showed that increasing carbon content results in the reduction of corrosion resistance in silver oxide electrodes. Moreover, the results of electric discharge test revealed that the silver oxide electrode containing 10wt% carbon yields the highest energy efficiency in the zinc‐silver oxide batteries.     

Electroless deposited Ni–P alloys: corrosion resistance mechanism

Electroless Ni–P alloys are produced as coatings on a broad variety of substrates. They exhibit a corrosion resistance that is superior to pure nickel but do not form a NiO oxide film (passive film) as pure nickel does. Despite the fact that many mechanisms have been proposed to explain this superior corrosion behaviour, no consensus has yet been reached. In this work electrochemical and XPS surface analytical methods have been combined in order to gain a deeper insight into the mechanisms underlying the corrosion resistance of electroless deposited Ni–P alloys with phosphorus content between 18 and 22 at.%. The anodic polarization curves in acidic and neutral solutions confirm a broad current plateau followed by a region with increasing current density. During potentiostatic polarization in the plateau region the current decays according to a power law with exponent ca. −0.5 indicating diffusion-limited dissolution of nickel. XPS/XAES measurements performed after potentiostatic polarization show that phosphorus is present in three different chemical environments. Based on the Auger parameter concept and on the chemical state plot, the three phosphorus states were assigned to phosphorus in the bulk alloy, phosphates and an intermediate phosphorus compound attributed to elemental phosphorus. Angle-resolved XPS analysis has shown that the elemental phosphorus is enriched at the interface between the alloy and the outermost surface in contact with the corrosive solution. These results suggest the following conclusions: the high corrosion resistance of electroless deposited Ni–P alloys can be explained by a strong enrichment of elemental phosphorus at the interface which limits the dissolution of nickel via a diffusion mechanism. A complementary explanation––not yet advanced––for the high corrosion resistance may lie in the electronic state of nickel in the Ni–P alloys.     

A novel method to detect unlabeled inorganic nanoparticles and submicron particles in tissue by sedimentation field-flow fractionation

 

A novel methodology to detect unlabeled inorganic nanoparticles was experimentally demonstrated using a mixture of nano-sized (70 nm) and submicron (250 nm) silicon dioxide particles added to mammalian tissue. The size and concentration of environmentally relevant inorganic particles in a tissue sample can be determined by a procedure consisting of matrix digestion, particle recovery by centrifugation, size separation by sedimentation field-flow fractionation (SdFFF), and detection by light scattering.

Background

Laboratory nanoparticles that have been labeled by fluorescence, radioactivity, or rare elements have provided important information regarding nanoparticle uptake and translocation, but most nanomaterials that are commercially produced for industrial and consumer applications do not contain a specific label.

Methods

Both nitric acid digestion and enzyme digestion were tested with liver and lung tissue as well as with cultured cells. Tissue processing with a mixture of protease enzymes is preferred because it is applicable to a wide range of particle compositions. Samples were visualized via fluorescence microscopy and transmission electron microscopy to validate the SdFFF results. We describe in detail the tissue preparation procedures and discuss method sensitivity compared to reported levels of nanoparticles in vivo.

Conclusion

Tissue digestion and SdFFF complement existing techniques by precisely identifying unlabeled metal oxide nanoparticles and unambiguously distinguishing nanoparticles (diameter<100 nm) from both soluble compounds and from larger particles of the same nominal elemental composition. This is an exciting capability that can facilitate epidemiological and toxicological research on natural and manufactured nanomaterials.     

Graphite oxide as a precursor for the synthesis of disordered graphenes using the aerosol-through-plasma method

The synthesis and characterization of graphene-like materials, prepared by plasma processing of graphite oxide is described. The thermal exfoliation and reduction of graphite oxide was obtained by passing an aerosol of coarsely ground graphite oxide with no solvent through a low-power (900 W) microwave generated plasma, with argon as the carrier and plasma gas. The reduced material obtained by this aerosol-through-plasma method was characterized by powder X-ray diffraction, Raman, X-ray photoelectron and solid state ¹³C NMR spectroscopy, transmission electron microscopy, thermo-gravimetric and elemental analysis and surface area analysis methods. These materials consist of single to few-layers of graphene and displays high disorder, large surface areas (∼640 m²/g) and low (<4%) oxygen content.     

磁控溅射氧化钒薄膜的研究进展

氧化钒因其优秀的相变特性和电阻开关特性而广受关注,在氧化钒薄膜多种制备工艺中,磁控溅射法优势明显。本文总结了近年来国内外研究者对磁控溅射法制备氧化钒薄膜的基础工艺研究成果,概述了不同溅射工艺对二氧化钒薄膜结晶特性及光学、电学性能的影响,并对相关机理进行了简要分析。相关结论对氧化钒薄膜的性能提高和应用扩展有一定的指导意义。     

Study of oxide layer formation on Inconel 718 during isothermal oxidation between 800 °C to 1200 °C in hot air

The present study is to investigate the isothermal oxidation behavior of Inconel 718 (a Cr/Ni/Mo/Si-based alloy) because of their excellent thermo-mechanical properties, which are important in aerospace applications. X-ray diffraction (XRD) study confirmed the formation of spinel element of NiCr₂O₄ along with Cr₂Ni₃ at 1000 °C. X-ray photoelectron spectroscopy (XPS) is used to define the elemental composition of oxides and Raman spectroscopy to ascertain the state of oxides. Different morphologies such as tetragonal biaxial pyramids, flakes, and polygonal plates were observed on heated samples. Cross-sectional and EDS studies clearly revealed the drastic increase of oxide layer from 800 °C to 1200 °C. Finally, electrochemical impedance spectroscopy (EIS) analysis was carried out at 800 °C, 1000 °C and 1200 °C with a tenant period and ramping rate of 24 h and 10 min respectively. The EIS results divulged that charge transfer resistance values drastically increased with increasing temperature due to oxide layer.     

Synthesis and characterization of telechelic phosphine oxide polyesters and cobalt(II) chloride complexes

A monofunctional phosphine oxide containing endcapping reagent, 4-carboxyphenyl biphenyl phosphine oxide, was synthesized for the preparation of telechelic polyester oligomers. The chemical structure of the endcapping reagent was verified using NMR spectroscopy, mass spectroscopy, and elemental analysis. Phosphine oxide telechelic polyesters were prepared for the first time via copolymerization of a low molar mass polyester oligomer precursor and the phosphine oxide endcapping reagent in the melt state. The quantitative incorporation of telechelic phosphine oxide functionality was confirmed using ¹H NMR spectroscopy and elemental analysis. The corresponding complexes of phosphine oxide terminated polyesters and cobalt(II) chloride were prepared via charging the cobalt salt at the onset of melt polymerization. ³¹P {¹H} NMR spectroscopy, FT-IR spectroscopy, and UV-vis spectroscopy indicated that the cobalt(II) ion preferentially coordinated with the phosphine oxide end groups. The complexes exhibited higher melt viscosity than their salt-free analogues due to the formation of coordinated polymers. The presence of the telechelic phosphine oxide end groups also aided in the homogeneous dispersion of the cobalt salt in a poly(ethylene terephthalate) (PET) matrix.     

炼焦过程利用含锌粉尘实现高温焦炉煤气脱硫的实验与模拟

提出了在炼焦过程中利用含锌粉尘作为焦煤添加剂，从而实现高温焦炉煤气脱硫的设想.热力学模拟计算和实验表明，在炼焦前期，含锌粉尘是非常有效的缚硫剂. 而在炼焦后期，在炼焦室中锌呈气态从半焦中进入焦炉煤气，在焦炉煤气离开炼焦室后，气态锌与硫化氢反应生成固态硫化锌. 脱硫产物自动从焦炉煤气中分离出来，从而实现了焦炉煤气的脱硫. 锌在焦炭中残留极少；氧化铁的存在有助于炼焦后期半焦中锌的挥发；含锌粉尘对焦炭质量的影响很小.