Variation of the photoluminescence and vacuum ultraviolet excitation characteristics of BaZr(BO3)2:Eu3+ by the incorporation of Al3+, La3+, or Y3+ into the lattice

The photoluminescence (PL) and vacuum ultraviolet (VUV) excitation properties are studied for the BaZr(BO₃)₂:Eu³⁺ phosphor with incorporating the Al³⁺, La³⁺, or Y³⁺ ion into the lattice. The excitation spectrum shows an absorption band in the VUV region with the band-edge at 200 nm and a very weak charge transfer band of Eu³⁺ at about 226 nm. The luminescence spectrum shows a strong emission at 615 nm (⁵D₀ → ⁷F₂ transition) and weak emission at 594 nm (⁵D₀ → ⁷F₁ transition) in BaZr(BO₃)₂:Eu³⁺, with a good red color purity. The PL intensity is increased by incorporating Al³⁺ into the BaZr(BO₃)₂ lattice. The PL intensity has also increased by incorporating La³⁺ into the lattice, however, the red color purity has deteriorated because of the increased centrosymmetric nature of the site. With the incorporation of Y³⁺ into the BaZr(BO₃)₂ lattice, the PL characteristics of the Eu³⁺ activator resembles that in the YBO₃ lattices. The intensity of the red PL for the Eu³⁺ activator is the highest with good color purity for BaZr(BO₃)₂:Eu³⁺ incorporated with both Al³⁺ (10%) and La³⁺ (0.5%).     

Nanostructure SnO2 and supported Au catalysts: Synthesis,characterization, and catalytic oxidation of CO

Nanostructure tin dioxide (SnO₂) powders prepared by sol-gel dialytic processes using tin (IV) chloride and anhydrous alcohol as start materials, ammonia gas as catalyst of the formation of colloid solution and agent of removing Cl⁻, and by introducing dialytic processes to improve and accelerate the formation of gels. From the result of TG–DTA analyses, the dried samples were calcined at 673 K in air for 3 h. Tin dioxide nanoparticles were characterized by thermogravimetry and differential thermal analyses (TG–DTA), X-ray diffraction (XRD), nitrogen adsorption–desorption, X-ray photoelectron spectroscopy (XPS). The average particle size of the as-prepared tin dioxide was about 5 nm. The as-prepared SnO₂ possessed mesoporous structure and large surface area. The Au/SnO₂ catalysts for low-temperature CO oxidation were prepared by the deposition–precipitation method using as-prepared SnO₂ powders as the support. The Au/SnO₂ catalysts exhibited high catalytic activity for low-temperature CO oxidation. The nanostructure SnO₂ has promising applications in sensor, catalyst, catalytic support, mesoporous membranes, etc.     

PVC一次性使用输液器中可沥滤物研究

通过模拟临床使用PVC一次性输液器的输注,对一次性使用输液器中可沥滤物进行了分析。建立了增塑剂邻苯二甲酸二(2-乙基己基)酯(DEHP)的高效液相分析方法,粘合剂环己酮的顶空气相色谱分析方法及金属元素(Cr、Cu、Cd、Sn、Ba、Pb)的电感耦合等离子体质谱分析方法。结果表明DEHP在3.674~104.970μg/mL范围内线性关系良好(r=0.9995),平均回收率为99.1%(n=9,RSD=1.7%);环己酮在0.5100~10.201μg/mL浓度范围内线性关系良好(r=0.9995),平均回收率为101.1%(n=9,RSD=2.4%);六种金属元素在0~100μg/L浓度范围内线性关系良好(r=0.9999),平均回收率在97.8%~110.6%(n=9,RSD≤2.8%)。本文建立的方法准确、灵敏,适用于PVC输液器中DEHP、环己酮和金属元素的溶出进行测定,为标准完善、质量监督及相关风险评价提供了参考依据。     

文化维度理论视域下的《迷失东京》研究

《迷失东京》是一部表现人生迷惘的电影。人生方向的迷失与个体所处的人生阶段密切相关。像星途暗淡又逢迈入中年、大学毕业即步入婚姻殿堂这样重大的人生变化都会使个体对人生道路产生迷茫。在一个语言不通,文化迥异的环境中,这种迷失感会愈发强烈。文章旨在运用霍夫斯泰德的文化维度理论分析影片中所展现的文化差异及其对男女主人公所产生的影响。     

3D QSAR Studies,Pharmacophore Modeling and Virtual Screening on a Series of Steroidal Aromatase Inhibitors

Aromatase inhibitors are the most important targets in treatment of estrogen-dependent cancers. In order to search for potent steroidal aromatase inhibitors (SAIs) with lower side effects and overcome cellular resistance, comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were performed on a series of SAIs to build 3D QSAR models. The reliable and predictive CoMFA and CoMSIA models were obtained with statistical results (CoMFA: q² = 0.636, r²_ncv = 0.988, r²_pred = 0.658; CoMSIA: q² = 0.843, r²_ncv = 0.989, r²_pred = 0.601). This 3D QSAR approach provides significant insights that can be used to develop novel and potent SAIs. In addition, Genetic algorithm with linear assignment of hypermolecular alignment of database (GALAHAD) was used to derive 3D pharmacophore models. The selected pharmacophore model contains two acceptor atoms and four hydrophobic centers, which was used as a 3D query for virtual screening against NCI2000 database. Six hit compounds were obtained and their biological activities were further predicted by the CoMFA and CoMSIA models, which are expected to design potent and novel SAIs.     

Evaluation of the lift-off robustness of eddy current imaging techniques

The development of lift-off invariant strategies is one of the main goals in Eddy Current Non-Destructive Testing research. In the present work, from the analysis of amplitude and phase signals of magnetic field sensors under Multi-Frequency Eddy Current excitation, two imaging procedures are analyzed and compared with respect to their ability to retrieve reliable results even in presence of huge changes of lift-off. A figure of merit based on the Signal to Noise Ratio evaluated on the 2D reconstructed images allows the comparison of the different strategies in terms of the quality of the image to show the defect. The numerical and the experimental tests realized show that the imaging procedure relying on the analysis of the phase-lag is quite insensitive to changes in the lift-off with respect to that based on the amplitude analysis. In detail the former guarantees good results even when the probe lift-off is randomly changed during the test with variations up to 3 mm, while the latter is able to tolerate only lift-off fluctuation lower than 1 mm.     

Sn-induced CuO–CeO2 catalysts with improved performance for CO preferential oxidation in H2-rich streams

Sn modified CuO–CeO₂ catalysts with different Sn loadings were prepared by a facile, green and solvent-free method. The effect of Sn/Ce ratio over Sn–Cu–Ce-x (x = 0, 1, 2.5, 5, 7.5) samples on CO activity and O₂ selectivity was investigated. The samples were characterized by various techniques using N₂-adsorption/desorption, XRD, H₂-TPR, XPS, Raman and in-situ DRIFTS. It was revealed that stronger interaction between acitve sites and support, higher amounts of Sn²⁺ and Ce³⁺, associated with increased amount of oxygen vacancies, were observed on the catalyst of Sn–Cu–Ce-5. As a result, the optimized catalyst displayed an excellent catalytic performance even in the presence of CO₂ and H₂O. In this sense, probing the Sn modified CuO–CeO₂ catalyst can elucidate some useful keys for the development of high CO₂ and H₂O-resistance catalyst during CO-preferential oxidation in H₂-rich streams.     

Structural,electrical and mechanical properties of selenium doped thallium based high-temperature superconductors

In this study, highly-refined chemical powders were synthesized by having them ready in appropriate stoichiometric proportions with conventional solid state reaction method so that they would produce the superconductor TlPb_0.3Sr₂Ca_1−xSe_xCu₂O_y (x = 0; 0.4; 0.6; 1.0). This study aims to understand effect of the selenium doping on the superconducting, structural and mechanical properties of the aforementioned superconducting material. The effect of the doping rates on the structural and electrical properties of the sample has been identified. Electrical characteristics of the TlPb_0.3Sr₂Ca_1−xSe_xCu₂O_y material were measured using standard four point probe method. Structural characteristics were examined with the powder X-ray diffractometer (XRD) and scanning electron microscope (SEM). Mechanical properties were analyzed with Vickers microhardness measurements on the sample surface. According to the results, it was observed that the reflection comes from the (00l) and parallel planes increased with Se doping. Particle size increases with increasing doping ratio. According to results of the mechanical measurements, all samples exhibit indentation size effect (ISE) behavior. Comparing the obtained results with theoretical studies, it was understood that Hays Kendall approach is the best method in determination of mechanical properties and analyzing microhardness of the materials.     

Vibration component separation by iteratively using stochastic resonance with different frequency-scale ratios

It is well-known that stochastic resonance (SR) is mainly used for signal denoising and weak signal detection. In this paper, we firstly find the frequency range selection characteristic (filtering characteristic) of re-scaling frequency SR (RFSR) caused by the driving frequency limitation of bistable SR. It then follows that a novel approach to separate vibration components with different frequencies by iteratively using SR is explored. The frequencies of most vibration signals exceed the driving frequency limitation, thus by use of different frequency-scale ratios, the vibration signals with different frequency range can be extracted by RFSR. Firstly, a small frequency-scale ratio is used to obtain the vibration signal with a narrow frequency range, i.e. low frequency vibration. As the output of SR may have a phase lag, a simple phase-shift correction method is proposed to improve the accuracy of signal component separation. The phase-shift corrected signal of RFSR output is separated from the original vibration signal and the residue is treated as the new vibration signal. Then, increasing the frequency-scale ratio according to a searching algorithm, the vibration signal with higher frequency can be obtained by RFSR. Through this iterative process, several harmonic vibration components can be separated from the original noisy vibration signal. The proposed method, empirical mode decomposition (EMD) and Hilbert vibration decomposition (HVD) are respectively applied to analyzing a simulated vibration signal and extracting the fault feature of a rotor system. The contrastive results show that this proposed method has good frequency resolution and can successfully separate monocomponent harmonic signals from a strongly noisy multicomponent harmonic vibration signal while EMD and HVD cannot.