Effect of Yb3+ concentration on the green-yellow upconversion emission of SrGe4O9:Er3+ phosphors

This work presents the structural, morphological and luminescent, properties of SrGe₄O₉ (SGO):Er³⁺,Yb³⁺ phosphors. These phosphors were synthesized by simple combustion synthesis and subsequently annealed at 1100 °C. The XRD patterns revealed that all the SGO samples doped with Yb³⁺ concentrations from 2 to 10 at.% presented a trigonal pure phase (the Er³⁺ concentration was fixed to 1 at.%). The morphology of the SGO samples was analyzed by scanning electron microscopy and found that they are formed by microparticles with irregular shapes and average sizes in the range of 0.2 μm–3 μm. The luminescence measurements of the SGO:Er³⁺,Yb³⁺ samples showed the presence of two main emission bands at 551 nm (green) and at 662 nm (red) under excitation at 980 nm, which are associated to Er³⁺ transitions. For Yb concentration of 2 and 3 at.% the green band dominated, but the red band became more intense for Yb concentrations above 5 at.%. As result, the CIE coordinate changed from the green to the yellow region. The increase for the Yb content from 2 to 10 at.% also enhanced of the NIR emission of Er³⁺ ≈5 times and the maximum upconversion emission was observed for 8% of Yb concentration. Further, the surface of the SGO samples was analyzed by the FTIR technique in order to find OH groups which are common luminescent quenching centers, but these groups were not detected on the samples. Since the SGO samples presented tunable emission, absence of OH groups on their surface and stable crystalline structure for high Yb dopant concentrations, they could be good candidates as phosphors for solid state lighting or displays applications.     

超高压液相色谱-串联质谱法测定腐竹、米线、年糕中的乌洛托品

目的 建立腐竹、米线、年糕中乌洛托品的超高压液相色谱-串联质谱分析方法。方法 样品经粉碎后, 用乙腈提取, MCX小柱净化, Waters ACQUITYTM UPLC BEH HILIC色谱柱分离, 最后在电喷雾正离子多反应监测模式下, 用超高压液相色谱-串联质谱仪进行分析。结果 乌洛托品在1.00～100.00 μg/L的范围内呈现良好的线性关系良好, 线性方程为Y=2391.11X+253.197, R2大于0.99。该方法检出限(S/N=3)和定量限(S/N=10)分别为0.30 μg/kg 和1.00 μg/kg。在1.00、10.00、50.00 μg/kg三个添加水平下, 乌洛托品平均回收率为82.0%～107.0%, 相对标准偏差为6.3%～15.6%。结论 该方法操作简便、检出限低, 能够满足腐竹、米线、年糕中乌洛托品检测的要求。     

饮用水中臭氧消毒副产物溴酸盐含量的控制技术探讨

在阐述臭氧化过程中溴酸盐的生成机理的前提下,从原水预处理、溴酸盐形成过程控制、溴酸盐形成后消除3个阶段来分析研究控制饮用水中溴酸盐含量的方法。经过探讨和实践表明,采用膜分离技术(控制原水电导率和微生物含量)、加氨、采用新型消毒剂和多种消毒剂组合使用、优化臭氧消毒工艺和活性炭吸附技术等是较为可行的控制途径。饮用水生产企业根据水源特点,生产能力,企业规模、运行成本等条件进行选择尝试,从而实现臭氧、微生物和溴酸盐之间的平衡。     

Degradation assessment and life prediction of electro-hydraulic servo valve under erosion wear

This paper presents a degradation assessment and life prediction method for electro-hydraulic servo valve (EHSV). Unlike traditional statistical methods, our work is motivated by the failure mechanism of erosion wear. The degradation of performance characteristic was related with structure wear in twin flapper–nozzle valve and spool valve. Mathematic models of turbulent and erosion wear were established by the combined technologies of computational fluid dynamics and erosion theory. By visual simulation, we analyzed the erosion wear distribution and erosion wear rate under different contaminated oil conditions and working missions. Furthermore, degradation models of performance characteristic were built according to degradation trends of system performance under different erosive wear stages. Finally, the assessment results show that: (1) Hydraulic oil with contaminant particles will distinctly erode the sharp edges of valve bushing and spool. Besides, the erosion rate depends on valve structure and port opening size. (2) Wear at sharp edges of spool valve influences pressure gain, null leakage flow and lap. Furthermore, these performance indicators are monotonically degraded. With the definition of failure for the EHSV, the service life is 9000 missions by our simple mission profile.     

同位素内标UPLC -MS/MS法测定婴儿配方奶粉中性激素苯甲酸雌二醇残留

建立测定婴儿配方奶粉中性激素苯甲酸雌二醇的超高效液相色谱-串联质谱方法。样品前处理采用酶解、甲醇提取,经LC-C18和LC-NH2基固相萃取柱净化。苯甲酸雌二醇由超高效液相色谱-串联质谱(UPLC-MS/MS)分离、在正离子电离模式(ESI+)及多反应监测模式(MRM)下,以氘代诺龙-d3为内标进行定量检测。方法对婴儿配方奶粉中苯甲酸雌二醇的检出限(LOD)0.39μg/kg,定量限(LOQ)为0.95μg/kg。在4μg/kg和10μg/kg两个加标水平下,婴儿配方奶粉中苯甲酸雌二醇的回收率在76.5%～86.3%的范围内,相对标准偏差在9.7%～15.2%范围内。     

超高效液相色谱-串联质谱多组分检测牛奶中外源性激素残留

在多反应监测模式条件下采用正离子采集模式建立牛奶中7 种激素的超高效液相色谱- 质谱/ 质谱(UPLCMS/MS)检测方法。样品以甲醇溶液为提取剂超声辅助提取,经LC-C18 柱净化,经BEH-C18(100mm × 2.1mm,1.7μm)柱分离后进行UPLC-MS/MS 多反应监测模式下的定性及定量分析。7 种激素方法检出限为0.01～0.25μg/kg,定量限为0.06～0.5μg/kg,添加水平为10μg/kg 时,平均回收率为83%～124%,相对标准偏差为4.3%～24%。该法灵敏度高、检出限低、分析时间短、操作简便,可应用于实际样品检测。     

Battery impedance characterization through inspection of discharge curve and testing with short pulses

A simple method is proposed for battery impedance characterization at low frequencies (relevant to the electrochemical processes) and at higher frequencies (relevant to the double-layer process). The electrochemical impedance at very low frequencies is described using discharge curve information. This method makes it possible to distinguish between outwardly similar batteries that differ in backup times. The double-layer impedance at higher frequencies is characterized using short testing pulses. It is shown that the double-layer impedance of the negative electrode is observable in hertz range while the positive electrode is observable at the boundary to the millihertz range. The double-layer impedance of deeply discharged battery is observable at higher frequencies than the impedance of fully charged (or significantly discharged) battery because the electrodes are less overlapping in frequency and the spectrum shift to the higher frequencies is larger especially for the negative electrode.     

润滑油和纳米材料对蒸发两相流型影响模拟分析

理论模拟了润滑油、纳米材料的添加以及质量流量对蒸发换热管内制冷剂流体流型的影响。润滑油的溶入促使各流型转换提前,制冷剂质量流速越高,弹状流区域扩大,含量相同及特性相近的润滑油对两相流的影响相近,与纳米Al2O3的影响相比,纳米CuO的添加更加压缩了弹状流区域。     

发酵酒中甜蜜素的确证技术分析及解决方案

为了解决发酵酒中甜蜜素测定的基质干扰和离子丰度比偏差不能满足液相色谱-质谱法的要求的问题,将发酵酒样品挥去酒精,经水稀释后,以甲醇-5 mmol/L甲酸铵为流动相,以BEH C18色谱柱（100 mm×2.1 mm,1.7 μm）进行分离,采用多反应监测（MRM）正负离子同时采集模式分析,当甜蜜素含量≥2 mg/kg时,稀释后进行确认,当甜蜜素含量＜2 mg/kg时,采用WAX固相萃取小柱净化后进行确认。经过方法学验证,该方法线性关系良好,相关系数R2为0.999 2,在3个添加水平条件下的加标回收率为82%～109%,测定结果的相对标准偏差（RSD）为2.2%～8.6%（n=6）,方法检出限为0.03 mg/kg,定量限为0.1 mg/kg。该方法准确、稳定性好,从实际检测出发较好地解决了发酵酒中甜蜜素定性困难问题。     

Numerical analysis of cavitation erosion and particle erosion in butterfly valve

The investigation of butterfly valve applied in the circulation water filtration system (CWF) of one pressurized water reactor (PWR) nuclear power station is performed in the paper. A coupling computational fluid dynamics model combined multiphase, cavitation and discrete phase model has been built to simulate the cavitation erosion and particle erosion. The validity and rationality of the coupling model is sufficiently verified with the experiment of flow coefficient and effects of different factors including inlet pressure and valve opening angle are discussed in detail. The results reveal that the erosion of butterfly valve mainly occurs at the forward and backward part of valve disc. With the increase of inlet pressure, max velocity, mass flow rate, wall shear stress, turbulent intensity and particle erosion would increase. Mass flow rate, wall shear stress, turbulent intensity and particle erosion decrease with the decrease of valve opening angle. The simulation results are well consistent with the failure feature of butterfly valve applied in actual operation. The numerical analysis is expected to improve the erosion condition and reliability of butterfly valve.