Detection of multiple endocrine-disrupting chemicals in milk: Improved and safe high performance liquid chromatography tandem mass spectrometry method

Herein, an improved method for detecting the endocrine-disrupting chemicals in milk is presented, which is based on high performance liquid chromatography tandem mass spectrometry, coupled with a quick, effective, and safe method. The linearity of the proposed method was in the range of 0.05–100 μg/L, and all correlation coefficients were ≥0.9973. At three concentration levels, the spiked recoveries ranged from 77.7 to 107.5%, relative standard deviations ranged from 0.2 to 14.6%, limits of quantitation ranged from 0.1 to 40 μg/kg, limits of detection ranged from 0.03 to 13.3 μg/kg. The proposed method for the identification and quantitation of 26 endocrine disruptors present in milk is not only easy, fast, and cost-efficient but also provides a reference for the detection of various endocrine disruptors in milk and other dairy products.     

Qualitative-quantitative analysis of multi-mycotoxin in milk using the high-performance liquid chromatography-tandem mass spectrometry coupled with the quick,easy, cheap,effective, rugged and safe method

High-performance liquid chromatography-tandem mass spectrometry coupled with the quick, easy, cheap, effective, rugged and safe method was established for the qualitative and quantitative detections of 20 mycotoxins in milk. The linear range of this method was 0.01–10 μg/L and the correlation coefficients were all greater than or equal to 0.9933. At three levels of addition, the spiked recoveries ranged from 80.00 to 112.50%, relative standard deviations were 2.67–14.97%, limits of quantitation were 0.02–4.00 μg/kg, and limits of detection were 0.007–1.300 μg/kg. This developed procedure for the identification and quantitation of mycotoxins provided prospective support for quality regulation.     

Boundedness of Rough Singular Integral Operators on Homogeneous Herz Spaces with Variable Exponents

We establish the boundedness of rough singular integral operators on homogeneous Herz spaces with variable exponents. As an application, we obtain the boundedness of related commutators with BMO functions on homogeneous Herz spaces with variable exponents.     

Some iterative algorithms for positive definite solution to nonlinear matrix equations

This paper is concerned with the unique positive definite solution to a system of nonlinear matrix equations $X-A^*\bar{Y}^{-1}A=I_n$ and $Y-B^*\bar{X}^{-1}B=I_n$, where $A,B\in\mathbb{C}^{n\times n}$ are given matrices. Based on the special structure of the system of nonlinear matrix equations, the system can be equivalently reformulated as $V-C^*\bar{V}^{-1}C=I_{2n}$. Moreover, by means of Sherman-Moorison-Woodbury formula, we derive the relationship between the solutions of $V-C^*\bar{V}^{-1}C =I_{2n}$ and the well studied standard nonlinear matrix equation $Z+D^*Z^{-1}D=Q$, where $D$, $Q$ are uniquely determined by $C$. Then, we present a structure-preserving doubling algorithm and two modified structure-preserving doubling algorithms to compute the positive definite solution of the system. Furthermore, cyclic reduction algorithm and two modified cyclic reduction algorithms for the positive definite solution of the system are proposed. Finally, some numerical examples are presented to illustrate the efficiency of the theoretical results and the behavior of the considered algorithms.     

气相色谱-质谱指纹图谱在鉴别贵州茅台酒中的应用

应用气相色谱-质谱(GC-MS)建立了贵州茅台酒的指纹图谱,确证了贵州茅台酒中35种特征组分,并采用浙江大学的中药指纹图谱相似度计算软件对样品图谱之间的相似度进行了评价和鉴别。方法的精密度及重复性良好。研究考察了38个批次贵州茅台酒、5种由贵州茅台酒股份有限公司生产的酱香型系列白酒以及12种由其他厂家生产的白酒的指纹图谱与贵州茅台酒指纹图谱模板的相似度。结果表明,通过酒的特征组分比较和基于“夹角余弦法”的指纹图谱相似度分析,可以区分贵州茅台酒和其他不同酒精度、不同香型的白酒。所建立的方法为贵州茅台酒的真伪鉴定提供了技术储备。     

荧光光度法同时测定稀土氧化物中铈钆铽

在０．６ｍｏｌ．Ｌ＾－１的 到介质中,分别用２５２、２７３、２２０ｎｍ作为Ｃｅ＾３＋、Ｇｄ＾３＋、Ｔｂ＾３＋的激发波和燕生相应最佳发波长为３５０、３１０和５４４ｎｍ。用盐酸体系测定混合样比用硫酸体系测定时,Ｇｄ＾３＋的检出限提高一倍,Ｇｄ＾３＋抗Ｃｅ＾３＋的干扰能力提高１０倍。同时测定三种离子的回收率在９５．３％～１０８．１％之间。     

钱塘江鲴鱼类寄生单殖吸虫生态研究

本文报道了在两种新的池塘养殖鱼类细鳞斜颌鲴和黄尾密鲴呼吸器官中寄生的13种单殖吸虫的感染率和强度的季节变化;发现广温性种类8种,适宜生长的水温至少在4℃—32℃范围内,喜温性种类5种,它们不能忍受低于11.6℃的水温条件,所有种类的寄生高峰期均在春夏两季;研究了其中危害较重的6种优势指环虫的感染强度逐月变化的特点;探讨了非专一性寄生的Dactylogyrus tendiculus A·Gussev,1955的感染强度、产卵率与鱼类寄主的关系。     

Degradation and Stabilization of Poly(propylene carbonate)

Low‐molecular‐weight poly(propylene carbonate) resins, useful for polyurethane preparation, surfactant production and many other purposes, were obtained by copolymerization of CO₂ and propylene oxide. This study describes an investigation into their stability against thermal degradation, offers details of the random chain‐breaking and “unzipping” processes, and suggests possible methods to avoid degradation.     

890 mW Diode Pumped Nd∶YVO_4 Intracavity-doubled Red Light Laser

Ｔｈｅｒｅｉｓａｗｉｄｅｓｐｒｅａｄｎｅｅｄｆｏｒａｌａｓｅｒｓｏｕｒｃｅｉｎ1.3μｍｒｅｇｉｏｎｉｎｔｈｅｔｒａｎｓｍｉｓｓｉｏｎｗｉｎｄｏｗｏｆｓｏｌｉｃａｏｐｔｉｃａｌｆｉｂｅｒｓ.Ｆｕｒｔｈｅｒｍｏｒｅ,ｉｔｓｓｅｃｏｎｄｈａｒｍｏｎｉｃ(ＳＨ)...