微波辐射下苯偶姻的干法氧化反应

研究了微波辐射下干法氧化苯偶姻生成苯偶酰的反应。结果表明，硅胶和酸性氧化铝是本反应的良好载体，空气是良好的氧化剂。在较短时间内(8～15min)即可获得很高的产率(92%～98%)，为一种有效的苯偶姻氧化反应新方法。     

A 1.107 μm Yb3+-doped Phosphate Fiber Laser Pumped by a Ti:sapphire

Lasers and amplifiers in a single fiber have been developed rapidly, especially for optical fiber communication and various sensors, in the recent years. However, remarkable progress and achievement have been made mainly in silica fiber doped with rare earth elements. In this paper, we report the progress on the development of the Yb3+-doped phosphate fiber laser.     

Luminescence Enhancement from Silica-Coated Gold Nanoparticle Agglomerates Following Multi-photon Excitation

Multi-photon absorption induced luminescence (MAIL) from bare gold nanoparticles, silica-coated particles, as well as silica-coated agglomerated gold nanoparticles suspended in aqueous solution was studied by using time-resolved and steady-state luminescence spectroscopy. The nanoparticles were excited by femtosecond pulses of wavelengths ranging from 630 nm to 900 nm. The luminescence from the particles exhibits a broad spectrum in the UV and VIS region. The time-resolved measurements indicate a luminescence lifetime of a few ps, limited by the response of the experimental system. The studied dependence of the MAIL efficiency on the excitation wavelength showed that the luminescence from silica-coated agglomerates was enhanced over the whole range of excitation wavelengths, when compared to the luminescence from individual gold nanoparticles. The agglomerates show an almost excitation wavelength independent efficiency of the MAIL, while for individual nanoparticles a rapid decrease of the MAIL efficiency was observed with increasing excitation wavelength. The observed enhancement of the MAIL from the agglomerated nanostructures can be attributed to the presence of localized surface plasmon resonances in the spectral region corresponding to the excitation wavelengths. The high MAIL efficiency from the agglomerated nanoparticle structures in the near-infrared could be an advantage in the expanding field of luminescence-based-imaging, as well as in biosensor technology.     

Properties of the πh_(9/2)  νi_(13/2) band in odd-odd ~(188)Au

A new rotational band has been identified and assigned to 188Au for the first time using the 173Yb(19F,4nγ) reaction at the beam energies of 86 and 90 MeV. This band is proposed to be built on the πh9/2  νi13/2 configuration by comparing the band properties with known bands in neighboring nuclei. The prolate-to-oblate shape transition through triaxial shape has been proposed to occur around 188Au for the πh9/2  νi13/2 bands in odd-odd Au isotopes on the basis of total Routhian surface (TRS) calculations.     

原子核电荷半径的新公式

结合原子核的电荷半径的实验数据,详细分析了描述原子核电荷半径的经验公式,表明电荷半径的Z^1/3律优于A^1/3律.更细致的考察发现,对于远离β稳定线的核素,电荷半径具有近似线性的同位旋相关性.由此得到的同位旋相关的Z^1/3公式更适合描述原子核的电荷半径.     

Liquid-Phase Selective Oxidation of Propane on Silica-Supported Nafion Catalysts

The liquid-phase partial oxidation of propane in the presence of the Fen+/H2O2 Fenton system at 70℃ and 1.4 atm on silica supported Nafion catalysts has been investigated. The reaction proceeds via a radical reaction path the efficiency of which is improved by silica-supported Nafion catalysts. Because of the direct relationship between reaction rate and concentration of sulphonic acid sites of Nafion catalysts, it is inferred that the active phase enahnces the kinetics of propane conversion by promoting the rate of active radicals generation.     

TS分子筛的催化氧化性能研究Ⅴ.环己酮氨肟化反应

研究了自制的钛硅分子筛(TS-1)催化H_2O_2参与的环己酮氨肟化反应.结果表明,降低反应溶液中H_2O_2的浓度、增加NH_3用量有利于H_2O_2利用率、环己酮肟收率和选择性的提高,适宜的n(H_2O_2):n(酮)<1.0,n(NH_3):n(酮)>2.0.反应时间应控制在3.5h左右.对溶剂的研究显示,叔丁醇在溶剂中所占的体积对反应有较大的影响,在叔丁醇体积分数为0.2到0.8之间,实验获得了较好的结果.当n(NH_3):n(H_2O_2):n(酮)=2.0:1.0:1.0,叔丁醇体积分数为0.5,反应时间2.5h,反应温度353K时,H_2O_2利用率、环己酮肟收率和选择性分别达95%,94%和97%以上.并对空白实验结果和TS-1的重复性试验进行了讨论.     

过碳酸钠-醋酸酐作用下的Baeyer-Villiger反应

在醋酸酐介质中, 过碳酸钠可以与酮进行Baeyer-Villiger反应, 将它们氧化成相应的酯。其中脂环酮的反应结果较好, 环内酯的产率约为80%。芳香酮除芳环被活化的以外, 效果欠佳。当反应施加超声辐射后可显著加快反应速度, 并对过碳酸钠的作用机理进行了讨论。     

含吡啶环系西佛碱大环配合物和氮杂大环自由配体的合成

2,6-二羟甲基吡啶(1)经活性MnO_2氧化得到2,6-二甲酰基吡啶(2)。邻硝基苯酚与N-取代的二(氯乙基)胺在DMF溶液中反应,得到N-取代的1,5-二(邻硝基苯氧基)-3-氮杂戊烷(3a～3c),再经水合肼/Raney Ni还原,获得N-取代的1,5-二(邻氨基苯氧基)-3-氮杂戊烷(4a～4c)。利用Ba~(2 )作为模板离子,(2)分别与(4a～4c)反应,合成了一类新的含吡啶环系西佛碱大环配合物Ⅰ～Ⅲ,配合物Ⅰ、Ⅲ经与NaBH_4的乙醇溶液还原解络,得到氮杂大环自由配体Ⅳ和Ⅴ。所有西佛碱大环配合物和氮杂大环自由配体均经元素分析、IR、~1H NMR、MS等证实了它们的结构和组成。     

THERMODYNAMIC AND PARTICLE-DYNAMIC STUDIES ON SYNTHESIS OF SILICA NANOPARTICLES USING MICROWAVE-INDUCED PLASMA CVD

1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can …