Simultaneous determination of naphazoline and pyridoxine in eye drops using excitation–emission matrix fluorescence coupled with second-order calibration method based on alternating trilinear decomposition algorithm

A novel method is developed for the direct determination of naphazoline hydrochloride(NAP) and pyridoxine hydrochloride(VB6) in commercial eye drops. By using excitation–emission matrix(EEM)fluorescence coupled with second-order calibration method based on the alternating trilinear decomposition(ATLD) algorithm, the proposed approach can achieve quantitative analysis successfully even in the presence of unknown and uncalibrated interferences. The method shows good linearity for NAP and VB6 with correlation coefficients greater than 0.99. The results were in good agreement with the labeled contents. To further confirm the feasibility and reliability of the proposed method, the same batch samples were analyzed by multiple reaction monitoring(MRM) based on LC–MS/MS method.T-test demonstrated that there are no significant differences between the prediction results of the two methods. The satisfactory results obtained in this work indicate that the use of the second-order calibration method coupled with the EEM is a promising tool for industrial quality control and pharmaceutical analysis due to its advantages of high sensitivity, low-cost and simple implementation.     

超高效液相色谱-串联质谱法检测花生中36种农药及其代谢物残留

建立了花生中36种农药及其代谢物残留的超高效液相色谱-串联质谱(UHPLC-MS/MS)快速检测技术。采用乙腈提取,增强型脂质去除净化剂(EMR-Lipid)净化,正离子多反应监测(MRM)模式测定。结果表明,所有农药的线性相关系数均大于0.994,在0.005,0.01,0.10 mg/kg 3个加标水平下,36种农药的平均回收率为70.4%~119%,相对标准偏差(RSDs)为1.3%~19.4%,方法的定量下限为0.002 5~0.05 mg/kg。该方法简便、快速,灵敏度高、净化效果好,适用于花生中农药多残留的快速检测分析。     

固相萃取/液相色谱-串联质谱法测定食品中二甲基黄

建立了液相色谱-串联质谱(LC-MS/MS)测定食品中二甲基黄(DMY)的分析方法。样品经乙酸乙酯提取,二甲基黄专用固相萃取小柱(ProElut DMY SPE)净化,XDB-C18色谱柱(50 mm×4.6 mm,1.8μm)分离,并以5mmol/L乙酸铵水溶液(含0.1%(v/v)甲酸)-乙腈(含0.1%(v/v)甲酸)为流动相,梯度洗脱,电喷雾正离子模式(ESI~+)电离,多反应监测模式(MRM)检测,内标法定量。结果表明,DMY在0~50μg/L范围内线性关系良好,相关系数(r~2)均大于0.999。方法的检出限(LOD,S/N3)和定量限(LOQ,S/N10)分别为2μg/kg和10μg/kg。不同食品基质中,DMY在10、20和100μg/kg的添加水平下的平均加标回收率为93.3%~98.9%,相对标准偏差为1.6%~3.9%(n=6)。该方法有效补偿了液相色谱-串联质谱检测过程中的离子化抑制效应,灵敏度和准确度高,适用于腐乳、辣椒酱、禽蛋、豆干、糖果和火腿中DMY的测定。     

Synthesis,characterization, and hydrolytic degradation of polylactide/poly(ϵ-caprolactone)/nano-silica composites

Poly(lactic acid) (PLA)/poly(?-caprolactone) (PCL)/nano-silica composite degradable films were prepared by a solvent casting method. SEM results showed that the nano-silica particles were dispersed uniformly in the PLA/PCL matrix. TGA results indicated that the thermal decomposition temperature rose with the increase of nano-silica content. The tensile strength of the composites was enhanced with the increase of nano-silica content up to 2%. The tensile strength increased with the silica content and reached its maximum (22.51 Mpa). The improvement in the water uptake ratio in the PLA/PCL/silica nanocomposites may be attributable to the presence of silica nanoparticles in the PLA/PCL matrix. After 15 weeks total processing time for the solution of alkaline and phosphate buffer, the performances of 16.23% and 3.65% for degradation.     

基于严格α-双链对角占优矩阵的非奇H-矩阵的判定准则

研究了非奇H-矩阵的判定问题.先给出了几个判定严格α-双链对角占优矩阵的充要条件,进一步利用矩阵对角占优理论得到了判定非奇H-矩阵的一些充分条件,推广和改进了已有的相关结果,并用数值算例说明了这些判定方法的有效性.     

一类含时滞的比率依赖捕食系统正平衡点的全局稳定性分析

讨论了一种食饵增长为Gilpin-Ayala型的比率依赖的食饵捕食者模型,利用第二加性复合矩阵原理证明线性化系统正轨道解的稳定性,结合系统在凸集中存在唯一的局部正平衡点,证明了正平衡点的全局渐近稳定性.结合数值模拟验证了所得结论的合理性,同时指出定理结论仅为充分条件,丰富完善了模型的动力学性质.     

浅析几类双输入排队系统模型

从矩阵几何解的角度出发,分析了七种类型的Geom/Geom/(Geom/Geom)/H 双输入排队系统.对这几个模型进行了描述,使用拟生灭过程探讨了各类模型的矩阵结构,并给出了其状态转移概率矩阵.     

高维约束矩阵回归问题

高维约束矩阵回归是指高维情况下带非凸约束的多响应多预测统计回归问题,其数学模型是一个NP-难的矩阵优化,它在机器学习与人工智能、医学影像疾病诊疗、基因表达分析、脑神经网络、风险管理等领域有广泛应用.从高维约束矩阵回归的优化理论和算法两方面总结和评述这些新成果,同时,列出了相应的重要文献.     

矩阵优化扰动性分析的若干进展

由于近年来实际问题特别是大数据应用的发展,矩阵优化问题越来越得到优化研究者,甚至是其他领域的研究者的高度关注,成为热点问题.优化问题的扰动性分析是优化理论研究的基础与核心,为包括算法设计在内的优化研究提供重要的理论基础.由于矩阵优化问题的非多面体性,使得相应扰动分析理论的研究本质上与经典的多面体优化问题(非线性规划)不同.结合文献[1,2],简要介绍矩阵优化扰动性分析方面取得的若干最新进展.     

Non-synchronous oscillations in four-dimensional nonlinear semelparous Leslie matrix models

In a certain class of semelparous Leslie matrix models, either a positive equilibrium is stable and an invariant set on the boundary of the nonnegative cone is unstable or vice versa generically if the model dimension is two or three. This dynamic dichotomy is expected to be failed in the four-dimensional case. Our study focuses on a semelparous Leslie matrix model with specific nonlinearities and rigorously proves that the dynamic dichotomy does not hold in the four-dimensional case. This result is derived by showing that the four-dimensional semelparous Leslie matrix model can be uniformly persistent with respect to the boundary of the nonnegative cone even if there exists an unstable positive equilibrium. In such a situation, there are no missing age-classes but population oscillation occurs.