两个投影算子的组合的幂等性

研究了两个交换的投影算子P和Q的组合aP+bQ+cPQ(a≠0,b≠0)的幂等性,并给出了它们的值域与核.利用矩阵的CS-分解研究了两个正交投影算子P和Q的组合aP+bQ+cPQ(a≠0,b≠0)的正交幂等性,证明了只有当两个正交投影算子P与Q交换时,aP+bQ+cPQ才有可能是正交幂等的.这些结果刻画了两个投影算子的一些重要特性.     

Fluorescence sensing of Cu within a pseudo 18-crown-6 cavity

We report herein a pseudo-crown based fluorescent receptor (1) for the selective detection of Cu²⁺ cation. Receptor 1 can detect Cu²⁺ even in 5 μM level in acetonitrile-water (9:1 v/v). Compound 1 is very effective for the detection of Cu²⁺ amongst the series of metal ions studied (Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, Ba²⁺, Pb²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Mn²⁺).     

Die trikline Kristallstruktur von Ag2Bi2S3Cl2: Pseudosymmetrie und Zwillingsbildung

Ruby‐red crystals of Ag₂Bi₂S₃Cl₂ were synthesized from AgCl and Bi₂S₃ by cooling a melt from 770 K to room temperature. X‐ray diffraction on powders and single‐crystals revealed a triclinic crystal structure with special lattice constants (P &1macr; (No. 2), a = 1085.0(2), b = 717.2(1), c = 1137.6(1) pm, α = 89.80(1)?, β = 74.80(1)?, γ = 87.81(1)?). In the structure [Bi^IIIS₃Cl₄] polyhedra form 2[BiS_3/2Cl_4/4]^‐ double‐layers by sharing common faces and edges. The silver(I) cations between the layers are coordinated either octahedrally by sulfide ions or tetrahedrally by sulfide and chloride ions. The deviations from the monoclinic space group P 1 2₁/c 1 are small and induce twinning along [010]. Further pseudosymmetry is based on the stacking of layer packages with the symmetry of the layer group P (2/c) 2₁/c 2/b.     

Simultaneous determination of boscalid and fludioxonil in grape and soil under field conditions by gas chromatography/tandem triple quadrupole mass spectrometry

A gas chromatography–tandem mass spectrometry method was developed and validated to simultaneously determine boscalid and fludioxonil in grape and soil samples. These samples were extracted with 10 mL of acetonitrile and purified using a mixed primary secondary amine/octadecylsilane sorbent. The method showed good linearity (R² > 0.99) in the calibration range 0.005–2 μg/mL for both pesticides. The limits of detection and quantification for the two analytes in grape and soil were 0.006 and 0.02 mg/kg, respectively. Fungicide recoveries in grape and soil were 81.18–92.11% for boscalid and 82.73–97.67% for fludioxonil with relative standard deviations of 1.31–10.31%. The established method was successfully applied to the residual analysis of boscalid and fludioxonil in real grape and soil samples. The terminal residue concentrations of boscalid and fludioxonil in grape samples collected from Anhui and Guizhou were <5 mg/kg (the maximum residue limit set by China) 7 days after the last application and 1 mg/kg (the maximum residue limit set by USA) 14 days after the last application. These results could provide guidance for the proper and safe use of boscalid and fludioxonil in grape and help the Chinese government to establish an MRL for fludioxonil in grape.     

Classification of chromatographic data using multidimensional polynomials

Summary A pattern recognition methodology has been developed for analysis of chromatographic data. The method uses a new class of multidimensional orthogonal polynomials developed by Cohen in conjunction with a supervised learning technique. The method is applicable to any chromatographic data for which classification into two or more categories is desired. The algorithm analyzes both elution times and peak areas. An application is shown for the analysis of organic acids in ascitic fluid obtained from patients with liver disorders. Classification of these patients for presence or absence of bacterial infection shows over ninety percent correct classification.     

有限局部环上对称矩阵的计数定理(I)

设$A_{n}(R)$是有限局部环$Z/p^{k}Z$上$n$阶对称矩阵的集合, 这里$n\geq 2$. $p$是大于$2$素数, $p\equiv1({\rm mod}4)$ 且$k>1$. 通过确定有限局部环$Z/p^{k}Z$上对称矩阵的标准型, 计算出$A_{n}(R)$在线性群${\rm GL}_{n}(R)$作用下的轨道数, 从而计算出由特定对称矩阵确定的正交群的阶以及与特定对称矩阵在同一轨道的对称矩阵的阶.     

基于正交试验法的显微镜上照明设计

根据LED光源特性和目标面光强的分布要求,采用正交试验法,对显微镜的LED照明系统进行优化设计。利用TracePro软件对所设计的系统进行光线追迹仿真,结果表明,在Φ50mm的范围内照度均匀性达到83.7%,能量利用率达到52.8%。该结构简单,成本低,易于实现。     

粒子群优化算法在光纤光栅传感器波长解调中的应用

为了提高光纤光栅(FBG)解调系统的波长解调精度,采用粒子群优化(PSO)算法结合参考光纤光栅(FBG),对常用波长解调器Fabry-Perot型光纤滤波器(FPF)的透射光谱中心波长与控制电压之间存在的非线性和回滞特性进行了研究,并提出一种实时建立FPF透射光中心波长与其控制电压之间关系模型的方法。该方法利用粒子群优化算法收敛快、易实现的特点,保证了FPF模型建立的准确性和实时性。实验结果证明,利用所建模型可有效提高FBG传感系统的波长测量准确度,测量误差不超过25 pm。系统结构简单,对提高FBG传感系统的测量准确度具有重要意义。     

主链型阳离子表面活性剂聚季铵盐的制备

以N,N-二甲基-1,3-丙二胺、尿素及1,4-二氯丁烷为原料,通过共缩聚反应两步法制备了一种新的主链型的水溶性聚季铵盐.采用正交试验获得了制备聚季铵盐的最佳条件：N,N-二甲基-1,3-丙二胺与尿素的物质的量比为2∶1,反应温度为135℃,反应时间为11h,得到中间体双[3-（N,N-二甲基丙胺基）]丙脲,产率高达99％;中间体与1,4-二氯丁烷的物质的量比为1∶1,于90℃下反应6h.采用红外光谱和核磁氢谱对产物结构进行表征,测定了其热稳定性和特性粘数.