基于函数型数据的系数正则化回归的收敛速度

本文研究了基于函数型输入和₁-正则化的最小二乘回归问题的推广性能.利用基于Rademacher平均的分析技术,获得了学习速度的估计,推广了已有的欧式空间有限维输入结果.     

Electrochemical Behavior of Caffeic Acid Assayed with Gold Nanoparticles/Graphene Nanosheets Modified Glassy Carbon Electrode

A gold nanoparticle (AuNP) and graphene nanosheet (GN) modified glassy carbon electrode (GCE) is proposed as voltammetric sensor for caffeic acid assay. The sensor exhibits a surface‐confined and reversible process for oxidation of caffeic acid revealed by cyclic voltammetry. The results show more favorable electron transfer kinetics than the bare GCE. The linear response of the sensor is from 5×10^?7 to 5×10^?5 M with a detection limit of 5×10^?8 M (S/N=3). The AuNP/GN nanocomposite shows more favorable electrochemical activity and should be a kind of more robust and advanced functional material, which provides a promising platform for electrochemical sensors and biosensors. The method was successfully applied to detect caffeic acid in pharmaceutical tablets with satisfactory results.     

新试剂1-（2-苯并噻唑）-3-（8-（5-对磺酸基苯基偶氮）)喹啉三氮烯（BTSPQT）的合成及其测定铜（Ⅱ）的研究

以2-氨基苯并噻唑和5-对磺酸基苯基偶氮-8-氨基喹啉为原料,合成了一种新的三氮烯试剂1-(2-苯并噻唑)-3-(8-(5-对磺酸基苯基偶氮))喹啉三氮烯(BTSPQT),并研究了该试剂与Cu2+的显色反应。结果表明,在含有0.3%Triton X-100的Na2B4O7-HCl缓冲体系(pH 8.0)中,BTSPQT与Cu2+在室温下可形成摩尔比为2∶1的紫红色配合物,该配合物的稳定常数为(2.59±0.40)×109,最大吸收波长位于610 nm。基于此反应,建立了一种测定Cu2+的光度分析新方法,其表观摩尔吸光系数为3.61×105L.mol-1.cm-1,线性范围为0.025～0.40 mg/L,且浓度在2.5 mg/L以下的常见离子均不干扰0.40 mg/L Cu2+的测定。将该方法用于面粉和茶叶中铜的直接测定,回收率为96%～103%,相对标准偏差均小于4.0%。     

Fabrication,patterning and luminescence properties of X2–Y2SiO5:A (A=Eu3+, Tb3+, Ce3+) phosphor films via sol–gel soft lithography

X₂–Y₂SiO₅:A (A=Eu³⁺, Tb³⁺, Ce³⁺) phosphor films and their patterning were fabricated by a sol–gel process combined with a soft lithography. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy (SEM) optical microscopy and photoluminescence (PL) were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 900 °C with X₁–Y₂SiO₅, which transformed completely to X₂–Y₂SiO₅ at 1250 °C. Patterned thin films with different band widths (5 μm spaced by 5 μm and 16 μm spaced by 24 μm) were obtained by a soft lithography technique (micromoulding in capillaries, MIMIC). The SEM and AFM study revealed that the nonpatterned phosphor films were uniform and crack free, and the films mainly consisted of closely packed grains with an average size of 350 nm. The doped rare earth ions (A) showed their characteristic emissions in X₂–Y₂SiO₅ phosphor films, i.e., ⁵D₀–⁷F_J (J=0,1,2,3,4) for Eu³⁺, ⁵D_{3, 4}–⁷F_J (J=6,5,4,3) for Tb³⁺ and 5d (²D)–4f (²F_{2/5, 2/7}) for Ce³⁺, respectively. The optimum doping concentrations for Eu³⁺, Tb³⁺ were determined to be 13 and 8 mol% of Y³⁺ in X₂–Y₂SiO₅ films, respectively.     

石屏井水中金属元素的分析

用原子吸收光谱法测定了云南省石屏县城用于直接点制豆腐的城内(北门、西门、南门)和城郊天然井水中Ca、Mg、Fe、Zn、Cu、Co、Cr、Ni和Cd等9种金属元素的含量,方法的相对标准偏差在0.28%—1.53%之间,回收率在97.68%—107.30%之间,分析结果满意。城中天然井水Ca和Mg含量非常高,Ca和Mg含量分别在207.83—268.50μg·mL-1和30.88—35.41μg·mL-1之间,其总硬度(以CaCO3计)在646.15—816.30μg·mL-1之间,为极硬水,西门外城郊井水中Ca含量仅为99.10μg·mL-1,Mg含量28.14μg·mL-1,都未检出Cd,其余6种金属元素在城中井水与郊外井水中的含量差别不大,且都较小;城中井水Ca、Mg含量:北门井水西门井水南门井水,井水中Ca和Mg含量在207.83、30.88μg·mL-1及其以上时,具有石膏或卤水凝固剂的作用,可直接点制豆腐;城中井水中Fe、Zn、Cu、Cr、Ni和Co含量大小为FeZnCrNiCuCo。     

Density Functional Theory Study of Water Diffusion and Clustering on Pd（111）

1 INTRODUCTION The interaction of water molecules with metal sur- faces plays a vital role in a number of important pro- cesses, such as corrosion, heterogeneous catalysis, electrochemical processes in aqueous solutions, hydrogen production, etc.[1] The structure and pro- perties of water adsorbed on well-defined metal sur- faces have been the subject of numerous experi- mental and theoretical investigations. There have been a number of experimental studies of water on metal surfaces throu…     

Deoxygenation reactions of c19-diterpenoid alkaloids

Efficient methods for deoxygenation of secondary and tertiary alcohols of some C₁₉-diterpenoid alkaloids are presented. Delphisine (12) was converted to 1-deoxydelphisine (19) via either 1,2-pyrodelphisine (17) or phenyl thionocarbonate 20. The following alkaloids were deoxygenated via their thiocarbonylimidazolyl derivatives: 14-acetyldelcosine (13) to 14-acetyl-l-deoxydelcosine (22); alkaline hydrolysis of 22 gave 1-deoxydelcosine (23); aconitine (24) to 3-deoxyaconitine (27); yunaconitine (25) to crassicauline A (28). Deoxygenation of 14-acetyldictyocarpine (30) via the chloro-derivative 31 gave 14-acetyl-10-deoxydictyocarpine (34). Reduction of 31 with LiAlH₄ gave the unusual elimination product 32. An improved partial synthesis of hypaconitine (35) from aconitine (24) is also presented.