Simultaneous determination of seven main alkaloids of Chelidonium majus L. by ultra‐performance LC with photodiode‐array detection

A simple and rapid method for the simultaneous determination of seven isoquinoline alkaloids, protopine, chelidonine, coptisine, stylopine, sanguinarine, berberine, and chelerythrine, in Chelidonium majus L. (Ch. majus) samples by ultra‐performance LC method with photodiode array detection is described. The baseline separation of these compounds was performed with (A) acetonitrile–(B) ammonium acetate (10 mM, adjusted to pH 3.0 with acetic acid) as the mobile phase using a C18 RP column (2.1×100 mm, 1.7 μm). Optimized conditions resulted in excellent peak shapes. The seven alkaloids were completely separated within 20 min. Good linear behaviors (r≥0.9992) over the investigated concentration ranges were observed for all the analytes. Validation proved the repeatability of the method was good and recovery was satisfactory. The validated method was successfully applied for 20 batches of Ch. majus. These results demonstrated that the ultra‐performance LC photodiode array method proposed was very useful in the analysis and quality control of Ch. majus.     

聚多巴胺涂敷的聚酰胺-胺功能化二氧化硅复合材料用于水样中苯甲酰脲类杀虫剂的分散微固相萃取北大核心CSCD

近年来,由农药残留导致的环境污染问题已引起社会的广泛关注,开发便捷高效的分析方法对农药残留进行检测和监测十分必要。研究设计并成功制备了聚多巴胺涂敷的聚酰胺-胺树状分子功能化的二氧化硅复合材料(SiO-PAMAM-PDA),并采用透射电镜对其进行表征。开发了以此复合材料为吸附剂的分散微固相萃取方法(D-μ-SPE),并结合高效液相色谱对水基质中的4种苯甲酰脲类杀虫剂(BUs)残留进行了富集检测。多巴胺结构中含有丰富的苯环、氨基及羟基,可与目标物形成氢键、π-π相互作用,从而增强了材料对苯甲酰脲的萃取能力。对吸附剂用量、萃取时间等可能影响萃取效率的条件进行了单因素优化。在最优条件下,该方法的线性范围在10~500μg/L之间,根据3倍信噪比(S/N)计算所得的检出限(LOD)为1.1~2.1μg/L,回收率为82.8%~94.1%,相对标准偏差(RSD)为2.1%~8.0%。将建立的方法与已报道的以苯甲酰脲作为目标物的方法进行了对比,发现方法样品用量及萃取剂用量均较少,且所需前处理时间较短,有机溶剂消耗也较少,为苯甲酰脲类农药的检测提供了更快速、绿色的选择。为评估所开发方法的实际样品适用性,将其应用于3种河水样品中4种苯甲酰脲类杀虫剂的分析检测,所得回收率及RSD分别为69.5%~99.4%和0.2%~9.5%,表明此方法在实际样品中同样具有较高的准确性和精密度。     

应用Dual PDA研究同轴交叉射流轴线速度衰减

采用Ｄｕａｌ　ＰＤＡ研究了２种射流交叉角度和４种密度比的同轴交叉射流的流场,发现射流交叉角度和密度比对射流流场有重要影响。提出了考虑了径向流动速度、密度差别的基于动量守恒的当量直径和当量速度。当量速度与实验结果较为吻合．对充分发展的射流,该法可较好的描述射流交叉角度、密度比对轴线上轴向速度的影响。     

声频下驻波管中微粒的悬浮现象及其相位多普勒测量

本文在声频信号下发现驻波管底部的微小颗粒群在一定声场强度下会腾空而起，在管中形成稳定的悬浮层。通过相位多谱勒（PDA）测量发现，只有粒径在一定范围内的颗粒才能稳定悬浮在管中，且颗粒悬浮层中颗粒的粒径按一定的高度规律分布，这一结果在粉尘颗粒分离，分级中有广阔的应用前景。     

Small moving infrared space target tracking algorithm based on probabilistic data association filter

Numerous false alarms for low signal-to-noise ratio (SNR) would seriously debase the performance for infrared low observable (LO) space target tracking. Due to the motion (i.e. azimuth, elevation and their derivative velocity), amplitude and size of infrared target are almost invariable and highly correlative, a multi-feature association approach based on probabilistic data association (PDA) is presented to track target in this paper. Firstly, the motion, amplitude and size of target are modeled as stationary random signal afforded Gaussian distribution. The probability of motion, amplitude and size of measurement originated as the target of interest is then estimated by Gaussian distribution, and that of false alarm is distributed uniformly. Subsequently, the combined probability of motion, amplitude and size is derived by PDA, and their weight coefficients are estimated adaptively according to their fluctuations. Finally, the relevant parameters including combination measurement are predicted and updated. Some experiments are included and the results show that the performance of target tracking by the proposed approach is significantly enhanced.     

气固两相圆湍射流颗粒对气相流动的影响

采用PDA测量气固两相圆湍射流中轴线上的气相轴向平均速度及轴向和径向湍流强度,并与相同出口速度的单相射流进行比较。研究不同颗粒对气相的调制作用。喷口直径为20 mm,出口Re为13600。采用了从50μm到300 μm不同平均直径的六种密度为2500 kg/m3玻璃微珠作为颗粒相。各组实验质量气载比为0.5。结果表明不同粒径的颗粒对两相流场中气相的平均速度、轴向和径向湍流强度均有不同影响。150μm以下的颗粒对气相湍流有明显抑制作用, 200μm以上颗粒对气相湍流有加强作用。颗粒对气相湍流调制规律的分界取与颗粒随拟序结构扩散的分界不同。     

近红外光谱法测定PDA中残留丙烯酰胺含量

选取38份实验室自制二甲基二烯丙基氯化铵与丙烯酰胺的共聚物(PDA)为样品,用紫外光谱法对PDA中残留丙烯酰胺(AM)含量进行测定,并进行近红外光谱扫描,在图谱中选取七个波段,将每个波段的特征峰作为自变量,吸收峰作为因变量,采用偏最小二乘法(PLS)的数学转换方法建立近红外反射光谱(NIRS)定标模型,采用小波分析对光谱进行降噪处理,建立PDA中残留AM含量的近红外预测模型,并将预测值与紫外光谱法测定值进行比较,其外部验证决定系数达到0.99,预测分布趋势良好,对预测值与实测值进行t检验,结果显示预测值与实测值差异不显著。试验结果表明,采用近红外光谱数据建立的定标模型预测PDA中残留AM单体含量具有较高可行性。     

径向浓浓淡旋流煤粉燃烧器直流二次风对气固流动的影响

本文综述了旋流燃烧器直流二次风对燃烧器区单相流动、烟气温度、煤粉燃尽及ＮＯｘ生成的影响,采用三维ＰＤＡ系统对不同直流二次风率下的气固速度分布、颗粒体积流量分布进行了测量,得出了其对气固流动的影响,分析了对燃烧器性能的影响。     

聚丁二炔Langmuir-Blodgett薄膜的光声谱研究(Ⅰ)结构表征与光声吸收系数

本文在用Ｘ－射线小角衍射对聚合与转载先后次序不同的ＰＤＡＬＢ膜进行结构表征的基础上,不同厚度ＰＤＡＬＢ膜的光声斩波频率效应说明,随着ＰＤＡＬＢ膜厚度增加,ＬＢ膜的热学性质逐渐明显。此外,还探讨了如何从ＰＤＡＬＢ膜的光声谱求得光声吸收系数问题,本文的研究结果表明,光声谱技术是研究ＬＢ膜热学特性的有效手段。