Microwave plasma torch mass spectrometry for the direct detection of copper and molybdenum ions in aqueous liquids

Microwave plasma torch (MPT) is a simple and low power‐consumption ambient ion source. And the MPT Mass spectra of many metal elements usually exhibit some novel features different from their inductively coupled plasma (ICP) mass spectra, which may be helpful for metal element analysis. Here, we presented the results about the MPT mass spectra of copper and molybdenum elements by a linear ion trap mass spectrometer (LTQ). The generated copper or molybdenum contained ions in plasma were characterized further in collision‐induced dissociated (CID) experiments. These researches built a novel, direct and sensitive method for the direct analysis of trace levels of copper and molybdenum in aqueous liquids. Quantitative results showed that the limit of detection (LOD) by using MS² procedure was estimated to be 0.265 µg/l (ppb) for copper and 0.497 µg/l for molybdenum. The linear dynamics ranges cover at least 2 orders of magnitude and the analysis of a single aqueous sample can be completed in 5–6 min with a reasonable semi‐quantitative sense. Two practical aqueous samples, milk and urine, were also analyzed qualitatively with reasonable recovery rates and RSD. These experimental data demonstrated that the MPT MS is able to turn into a promising and hopeful tool in field analysis of copper and molybdenum ions in water and some aqueous media, and can be applied in many fields, such as environmental controlling, hydrogeology, and water quality inspection. Moreover, MPT MS could also be used as the supplement of ICP‐MS for the rapid and in‐situ analysis of metal ions. Copyright © 2016 John Wiley & Sons, Ltd.     

Study on scattering correction in fast neutron tomography at NECTAR facility

Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor.Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction results,especially for hydrogenous material object.In this article,an iterative scattering correction method for fast neutron tomography was proposed.In each loop of iteration the scattering component of the projections will be simulated by Monte-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections.The differences between scattering components at different perspectives were quantitatively evaluated and an average scattering component image was used for all projections finally.Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correction,in which case the relative error of the reconstructed attenuation coefficients is about 10%–30%.     

Experiments and analysis of thin tungsten slice and W/Cu brazing for primary collimator scraper in CSNS/RCS

According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.     

A micro-scale strain rosette for residual stress measurement by SEM Moiré method

In this paper,a new method combining focused ion beam(FIB)and scanning electron microscope(SEM)Moirétechnique for the measurement of residual stress at micro scale is proposed.The FIB is employed to introduce stress relief like the macro ring-core method and fabricate gratings with a frequency of 5000 lines/mm on the measured area of the sample surface.Three groups of gratings in different radial directions are manufactured in order to form a micro-scale strain rosette.After milling ring-core by FIB,the deformation incurred by relief of the stress will be recorded with the strain rosette.The displacement/strain field can be measured using SEM scanning Moiréwith random phase-shifting algorithm.In this study,the Nickel alloy GH4169 sample(which was processed by laser shock peening)is selected as a study object to determine its residual stress.The results showed that the components of the in-plane principal stresses were-359 MPa and-207 MPa,respectively,which show good agreement with the results obtained from the available literature.     

Highly stable amorphous indium‐zinc‐oxide thin‐film transistors with back‐channel wet‐etch process

The stabilities of amorphous indium‐zinc‐oxide (IZO) thin film transistors (TFTs) with back‐channel‐etch (BCE) structure are investigated. A molybdenum (Mo) source/drain electrode was deposited on an IZO layer and patterned by hydrogen peroxide (H₂O₂)‐based etchants. Then, after etching the Mo layer, SF₆ plasma with direct plasma mode was employed and optimized to improve the bias stress stability. Scanning electron microscopy and X‐ray photoelectron spectroscopic analysis revealed that the etching residues were removed efficiently by the plasma treatment. The modified BCE‐ TFTs showed only threshold voltage shifts of 0.25 V and –0.20 V under positive/negative bias thermal stress (P/NBTS, V_GS = ±30 V, V_DS = 0 V and T = 60 °C) after 12 hours, respectively. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fermi liquid breakdown and evidence for superconductivity in YFe2Ge2

In the d‐electron system YFe₂Ge₂, an unusually high and temperature dependent Sommerfeld ratio of the specific heat capacity C /T ～ 100 mJ/(mol K²) and an anomalous power law temperature dependence of the electrical resistivity signal Fermi liquid breakdown, probably connected to a close‐by quantum critical point. Full resistive transitions and DC diamagnetic screening fractions of up to 80% suggest that pure samples of YFe₂Ge₂ superconduct below 1.8 K. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Reducing the Entropic Uncertainty via Non-Markovian Effect and Detuning in the Presence of Quantum Memory ∗

The influence of non-Markovian effect and detuning on the entropic uncertainty in the presence of quantum memory is studied by the time-convolutionless master-equation approach. The result shows that the entropic uncertainty in the presence of quantum memory is obviously dependent on both detuning and non-Markovian effect. The bigger the detuning is and the stronger the non-Markovian effect is, the smaller the entropic uncertainty is. Its physical explanation is that the known quantum information stored in the quantum memory can reduce or eliminate the entropic uncertainty about the measurement outcomes of another particle, which is entangled with the quantum memory.     

Solvothermal synthesis and electrochemical performance of Ag-doped V6O13 as cathode material for lithium-ion battery

For the first time, belt-like V₆O₁₃ precursor was synthesized via a simple solvothermal method. Rod-like Ag-doped V₆O₁₃ was successfully synthesized by this method followed by heating at 350 °C. Both crystal domain size, electronic conductivity, and the lithium diffusion coefficient of the Ag-doped V₆O₁₃ samples are influenced by the added amount of AgNO₃. When the amount of AgNO₃ is 0.008 g, the product is rod-like particles, which are 0.1–0.3 μm wide and 1–2 μm long, and exhibits the best electrochemical performance. The enhanced electrochemical performance originates from its higher total conductivity, higher lithium diffusion coefficient, and better structural reversibility.     

双流体等离子体模型的动力学可容变分

动力学可容变分方法是一种广义哈密顿系统中的李扰动变换方法,能自动保证卡西米尔函数在相应阶数上的守恒性质.通过动力学可容方法得到了双流体在欧拉描述中的一组约束变分,而后利用这组变分对双流体哈密顿量取极值得到了平衡方程.     

耦合系统的朗之万动力学产生法

提出一种朗之万动力学方法获取处于热平衡态耦合系统内部振子坐标,数值模拟了单端固定简谐振子链的时间演化行为,并将其平衡性质与解析解进行了比较.结果表明了朗之万动力学方法的有效性.推广应用于非简谐四次方型耦合系统,模拟得到振子的四次方均坐标,与理论值验证;以模拟结果作为样本点计算哈密顿量,其能量分布与Boltzmann分布相符.