稀土萃取分离过程软测量方法的研究

分析了稀土组分含量在线检测技术进展缓慢的原因,分析了稀土萃取分离过程机制,找出影响稀土组分含量检测的主要因素,确定辅助变量。利用从包钢稀土厂采集的数据通过newrb函数创建径向基网络来实现稀土组分含量的软测量。文中通过流程图详细阐述了建模方法,采用50组样本数据对所建立的模型进行计算机仿真验证,仿真结果证明了模型的可行性。     

Barium‐Mediated Cross‐Dehydrocoupling of Hydrosilanes with Amines: A Theoretical and Experimental Approach

Alkaline‐earth (most prominently barium) complexes of the type [Ae{N(SiMe₃)₂}₂?(THF)_x] and [{N^N}Ae{N(SiMe₃)₂}?(THF)_x] are very active and productive precatalysts (TON=396, TOF up to 3600 h^?1; Ca相似文献   

Rare Earth Ion Mediated Fluorescence Accumulation on a Single Microbead: An Ultrasensitive Strategy for the Detection of Protein Kinase Activity at the Single‐Cell Level

A single microbead‐based fluorescence imaging (SBFI) strategy that enables detection of protein kinase activity from single cell lysates is reported. We systematically investigated the ability of various rare earth (RE) ions, immobilized on the microbead, for specific capturing of kinase‐induced phosphopeptides, and Dy³⁺ was found to be the most prominent one. Through the efficient concentration of kinase‐induced fluorescent phosphopeptides on a Dy³⁺‐functionalized single microbead, kinase activity can be detected and quantified by reading the fluorescence on the microbead with a confocal fluorescence microscope. Owing to the extremely specific recognition of Dy³⁺ towards phosphopeptides and the highly‐concentrated fluorescence accumulation on only one microbead, ultrahigh sensitivity has been achieved for the SBFI strategy which allows direct kinase analysis at the single‐cell level.     

Effect of Y2O3 on microstructural characteristics and wear resistance of cobalt‐based composite coatings produced on TA15 titanium alloy surface by laser cladding

The effects of Y₂O₃ on the microstructure, phase composition of the coatings, microhardness and wear resistance of cobalt‐based composite coatings prepared by laser cladding were investigated. The TA15 titanium alloy was selected as substrate which the cobalt‐based composite powder with different content of Y₂O₃ was cladded on. The microstructure of the coatings was observed by scanning electron microscope (SEM) and metallurgical microscope. The phase structure of the coatings was determined by X‐ray diffraction (XRD), and the microhardness and wear resistance of the coatings were measured by hardness tester and wear testing machine. The results show that the rare earth oxide Y₂O₃ can refine and purify the microstructure of the coatings, reduce the porosities and cracks and improve compactness of the coatings. Moreover the addition of Y₂O₃ improves the microhardness of the coatings and reduces the friction coefficient, thus improving the wear property of the coatings. And the wear resistance of the coating with Y₂O₃ has improved about 50 times; the highest value of microhardness in the coating is HV1181.1. And 0.8 wt% content of Y₂O₃ in the coating is the best choice for improving the microhardness and wear resistance of the coating. It is feasible to improve the microstructure and tribological properties of laser cladding coatings by adding of Y₂O₃. Copyright © 2014 John Wiley & Sons, Ltd.     

Dependency of dynamic interlaminar shear strength of composites on test technique used

Studies are presented on dependency of dynamic interlaminar shear (ILS) strength on the experimental technique used for a typical plain weave E-glass/epoxy composite. Dynamic ILS strength was determined based on two experimental techniques, namely torsional split Hopkinson bar (TSHB) apparatus using thin walled tubular specimens and compressive split Hopkinson pressure bar (SHPB) apparatus using single lap specimens. The results obtained from these techniques are compared. In general, it is observed that dynamic ILS strength for composites obtained by TSHB testing using thin walled tubular specimens is lower than the dynamic ILS strength obtained using single lap specimens in compressive SHPB. The issues involved in TSHB testing of thin walled tubular specimens made of composites are discussed and the reasons for reduced dynamic ILS strength using thin walled tubular specimens are highlighted. Finite element analysis (FEA) of thin walled tubular specimens made of composite and resin subjected to quasi-static torsional loading is presented. Using FEA results, the reasons for lower ILS strength of composite thin walled tubular specimens are substantiated.     

Enhanced conformational sampling method for proteins based on the TaBoo SeArch algorithm: Application to the folding of a mini‐protein,chignolin

The conformational samplings are indispensible for obtaining reliable canonical ensembles, which provide statistical averages of physical quantities such as free energies. However, the samplings of vast conformational space of biomacromolecules by conventional molecular dynamics (MD) simulations might be insufficient, due to their inadequate accessible time‐scales for investigating biological functions. Therefore, the development of methodologies for enhancing the conformational sampling of biomacromolecules still remains as a challenging issue in computational biology. To tackle this problem, we newly propose an efficient conformational search method, which is referred as TaBoo SeArch (TBSA) algorithm. In TBSA, an inverse energy histogram is used to select seeds for the conformational resampling so that states with high frequencies are inhibited, while states with low frequencies are efficiently sampled to explore the unvisited conformational space. As a demonstration, TBSA was applied to the folding of a mini‐protein, chignolin, and automatically sampled the native structure (C_α root mean square deviation < 1.0 Å) with nanosecond order computational costs started from a completely extended structure, although a long‐time 1‐µs normal MD simulation failed to sample the native structure. Furthermore, a multiscale free energy landscape method based on the conformational sampling of TBSA were quantitatively evaluated through free energy calculations with both implicit and explicit solvent models, which enable us to find several metastable states on the folding landscape. © 2015 Wiley Periodicals, Inc.     

Lanthanide‐Doped Nanocrystals: Strategies for Improving the Efficiency of Upconversion Emission and Their Physical Understanding

The fundamental understanding of lanthanide‐doped upconverted nanocrystals remains a frontier area of research because of potential applications in photonics and biophotonics. Recent studies have revealed that upconversion luminescence dynamics depend on host crystal structure, size of the nanocrystals, dopant concentration, and core–shell structures, which influence site symmetry and the distribution and energy migration of the dopant ions. In this review, we bring to light the influences of doping/co‐doping concentration, crystal phase, crystal size of the host, and core–shell structure on the efficiency of upconversion emission. Furthermore, the lattice strain, due to a change in the crystal phase and by the core–shell structure, strongly influences the upconversion emission intensity. Analysis suggests that the local environment of the ion plays the most significant role in modification of radiative and nonradiative relaxation mechanisms of overall upconversion emission properties. Finally, an outlook on the prospects of this research field is given.     

UV Emission of Gd3+ in the Presence of Cu2+: Towards Luminescence Quenching through Quantum Cutting?

The first investigation into the ultraviolet (UV) photoluminescence of gadolinium(III) in the presence of copper(II) is reported. A melt‐quenched barium phosphate glass was used as a model matrix. The optical spectroscopy assessment shows that with increasing CuO concentration the Cu²⁺ absorption band grows steadily, whereas the UV emission from Gd³⁺ ions is progressively quenched. The data, thus, suggests the existence of a Gd³⁺→Cu²⁺ energy‐transfer process ocurring through quantum cutting. A downconversion/cross‐relaxation pathway proceeding through a virtual state in Gd³⁺ is proposed. These findings suggest gadolinium(III) could potentially be used in the optical sensing of copper(II).     

Note on rare Z-boson decays to double heavy quarkonia

Within the standard model, we have investigated rare Z-boson decays into double heavy quarkonia, \begin{document}$ Z\to VV $\end{document} and \begin{document}$ Z\to VP $\end{document}, with V and P denoting vector and pseudoscalar quarkonia, respectively. It is assumed that the leading-order QCD diagrams would give the dominant contributions to these processes, and the corresponding branching fractions, for instance, \begin{document}$ {\cal B}(Z\to J/\Psi J/\Psi) $\end{document}, have been estimated to be approximately\begin{document}$ 10^{-13} $\end{document} in literature. However, these decays could also happen through electromagnetic transitions \begin{document}$ Z\to V\gamma^* $\end{document} and \begin{document}$ Z\to P\gamma^* $\end{document}, with the virtual photon transforming into V. Interestingly, the smallness of the vector quarkonium mass can give rise to a large factor \begin{document}$ m_Z^2/m_V^2 $\end{document} relative to the QCD contributions, which thus counteracts the suppression from the electromagnetic coupling. We systematically include these two types of contributions in our calculation to predict branching fractions for these decays. Particularly, owing to the virtual photon effects, it is found that \begin{document}$ {\cal B}(Z\to J/\Psi J/\Psi) $\end{document} will be significantly enhanced, up to \begin{document}$ 10^{-10} $\end{document}.     

用平行双样测定结果相对偏差限值评估方法验证实验重复性限合理性的研究

分析方法标准验证实验得到的分析方法基本性能参数重复性限和再现性限是日常检测工作质控规范重要依据。以环境监测领域土壤、沉积物及固废样品中无机元素分析为例,考察了已颁布执行的标准文本和在生态环境部官网公开征求意见的分析方法标准中重复性限。将重复性限转化为相对偏差后,与日常检测工作中质控限值进行了比较。根据目前现行有效的平行双样测定结果相对偏差限值,方法验证数据有多大比例符合质控要求？根据方法验证结果,平行双样测定结果相对偏差限值有无改进可能？从上述两个角度进行了研究。研究结果表明：土壤、沉积物、固体废弃物中无机元素的测定,不同文献来源相同分析方法标准和不同分析方法标准,其重复性限转化得到的平行测定相对偏差合格率存在明显区别;用平行测定相对偏差限值可以快速判断标准文本中的重复性限是否合理,审核方法验证数据质量是否满足要求。基于已有标准文本方法验证数据,探讨了修改平行测定结果相对偏差限值可行性。