Structural characterization and identification of C19‐ and C20‐diterpenoid alkaloids in roots of Aconitum carmichaeli by rapid‐resolution liquid chromatography coupled with time‐of‐flight mass spectrometry

Aconite alkaloids from the roots of Aconitum carmichaeli (Fuzi, in Chinese) have been investigated by rapid‐resolution liquid chromatography coupled with time‐of‐flight mass spectrometry (TOFMS) in positive mode. With dynamic adjustment of the key role as fragmentor voltage in TOFMS, an efficient transmission of the ions was achieved to obtain the best sensitivity for providing the molecular formula for each analyte, and abundant fragment ions for structural information. Fifteen authentic standards isolated from Fuzi with various structures were first characterized by TOFMS, including diester‐diterpenoid alkaloids (DDAs), monoester‐diterpenoid alkaloids (MDAs), alkylol amine‐diterpenoid alkaloids (ADAs), veatchine‐type alkaloids and atisine‐type alkaloids. Fragmentation rules and key diagnostic fragment ions have been summarized, and possible pathways of fragmentation have been proposed. By accurate mass measurements within 5 ppm error for each ion, 30 C₁₉‐diterpenoid alkaloids including 10 DDAs, 3 MDAs, 9 ADAs and 8 other type alkaloids, and 8 C₂₀‐diterpenoid alkaloids including 4 veatchine‐type alkaloids and 4 atisine‐type alkaloids could be identified in a methanolic extract of Fuzi. Some isomers of aconite alkaloids were also differentiated. Based on the differences between their fragmentation pathways and special fragment ions, each type of aconite alkaloids was differentiated. Copyright © 2009 John Wiley & Sons, Ltd.     

The slagging propensity of Zn-rich scrap tyre ash in reducing environments consisting of CO and CO2 and its promotion of the slagging of Si-rich coal ash

This study includes a comprehensive investigation on the ash slagging characteristics of zinc (Zn)-rich tyre ash and its interaction with silica (Si)-rich coal ash blended at different ratios in a 5% CO in CO₂ reducing environment. Such an environment is expected to occur near the burner in a combustor, as well as serves as a fundamental study on the slagging propensity upon the effect of CO, which is a principal reducing agent in a gasifier. An approach consisting of experimental studies using modified inclined plane (M-IP) methodology, advanced analytical techniques including the scanning electron microscopy (SEM) and x-ray photoelectron (XPS) spectroscopy, and thermodynamic equilibrium calculations were used to elaborate the slagging propensities of the single and blended ashes. Furthermore, the fate of Zn within tyre ash and its potential implications on the slagging properties were evaluated. Tyre ash easily melts to liquid slag upon increasing temperature compared to the silica-rich coal ash. Zinc does not evaporate but rather remains within tyre slag mostly as a hemimorphite (Zn₄(Si₂O₇)(OH))-like coordination structure attributing to the characteristic blue colour of tyre slag. The low ionic potential value of 2.7 for Zn²⁺ is characteristic of basic ions that have a greater tendency to depolymerise the Si-rich ash slag matrix and acts as a fluxing agent in ash slag. Moreover, it was proven that Zn²⁺ plays a synergistic role with Ca²⁺ in enhancing the flowability of the Si-rich slag remarkably. Furthermore, for the pure tyre slag, Zn was found to preferentially deposit at the corundum (Al₂O₃) substrate interface and even penetrate/react with the porous corundum, causing a strong corrosion on the substrate. However, blending of tyre ash with coal ash alleviates this problem by a preferred scavenging of Zn into the entire Si matrix, which in turn protects the corundum plate.     

Synthesis and properties of a thiophene-substituted diaza[7]helicene for application as a blue emitter in organic light-emitting diodes

Carbazole-based diaza[7]helicene substituted by thiophene groups, 2,12-dithiophene-5,15-dihexyl-5,15-diaza[7]helicene (6), was synthesised successfully and confirmed by ¹H NMR, ¹³C NMR, High Resolution Mass Spectrometry, Time of Flight Mass Spectrometry. Compound 6 exhibited good solubility and excellent thermal stability with no melting point and a high decomposition temperature of 453.64 °C. A doped device with a structure of ITO/NPB (50 nm)/CBP: 10% 6 (30 nm)/Bphen (20 nm)/Mg:Ag (150 nm)/Ag (50 nm) emitted the blue light at 460 nm with Commission Internationale de LEclairage (CIE) coordinate of (0.176, 0.26). The maximum brightness and external quantum efficiency (EQE) were 2306 cd m^?2 and 0.41%, respectively.     

Fluorometric determination of the activity and inhibition of terminal deoxynucleotidyl transferase via in-situ formation of copper nanoclusters using enzymatically generated DNA as template

The authors report on a simple strategy for sensitive determination of the activity of terminal deoxynucleotidyl transferase (TdT) using copper nanoclusters (CuNCs) as fluorescent probes. TdT-polymerized long chain AT-rich DNA serves as a template for the synthesis of the CuNCs, and TdT activity is detected fluorometrically at excitation/emission wavelengths of 340/570 nm. The protocol relies on the target-triggered formation of dsDNA polymers and in-situ formation of CuNCs. The calibration plot is linear in the 0.7 to 14 U L^?1 activity range, with a 60 mU L^?1 detection limit (at a signal-to-noise ratio of 3). The protocol was applied to determine TdT activity in acute lymphatic leukemia cells. This approach is selective, simple, convenient and cost-efficient because a complex DNA sequence is not required. In our perception, the method provides a viable new platform for monitoring the activity and inhibition of TdT.

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Graphical abstract Based on the target-triggered formation of dsDNA polymers and in-situ formation of CuNCs with strong fluorescence, a turn-on fluorescence assay for TdT activity is presented.

     

Vulgarisins B–D,three novel diterpenoids with a rare skeleton isolated from Prunella vulgaris Linn

Three new diterpenoids, vulgarisins B–D (1–3), have been isolated from a medicinal plant Prunella vulgaris Linn. These diterpenoids contain a rare 5/6/4/5 fused tetracyclic ring skeleton. Their structures were determined through the analysis of spectroscopic data, and the absolute configuration were further confirmed by single crystal X-ray diffraction as well as CD analysis. All the compounds were evaluated for their cytotoxicity activity, vulgarisins B (1) and C (2) demonstrated modest cytotoxicity activity against human lung carcinoma A549 cell line.     

一种铈（Ⅲ）配合物对含石墨粘结涂层耐蚀性的影响

为了改善含石墨粘结涂层的耐蚀性，首先对这种涂层在腐蚀环境中耐蚀性差的原因进行了分析，然后将二正丁基磷酸、ＣｅＦ＿３、Ｓｂ＿２Ｏ＿３和一种Ｃｅ（Ⅲ）配合物Ｃｅ（ＮＯ＿３）（Ｃ＿８Ｈ＿（１８）ＰＯ＿４）＿２分别添加于酚醛环氧－ＭｏＳ＿２－石墨粘结涂层中，考察了它们对这种涂层耐蚀性的影响，并对含Ｃｅ（ＮＯ＿３）（Ｃ＿８Ｈ＿（１８）ＰＯ＿４）＿２的涂层和空白样涂层进行了表面分析。盐雾试验表明，添加Ｃｅ（ＮＯ＿３）（Ｃ＿８Ｈ＿（１８）ＰＯ＿４）＿２可以有效地抑制涂层中ＭｏＳ＿２的氧化和由石墨所引起的金属底材之电化学腐蚀；根据Ｘ射线光电子能谱分析结果可知，添加Ｃｅ（ＮＯ＿３）（Ｃ＿８Ｈ＿（１８）ＰＯ＿４）＿２之所以能够提高含石墨粘结涂层的耐蚀性，应当归因于它在ＭｏＳ＿２晶体表面和金属底材表面的吸附。因此，Ｃｅ（Ⅲ）配合物Ｃｅ（ＮＯ＿３）（Ｃ＿８Ｈ＿（１８）ＰＯ＿４）＿２是含石墨粘结涂层的一种实用性能良好的新型防腐添加剂。     

多化学组份反应气体流动的Godunov格式

本文将单介质气体流动的Goduoov方法推广到多化学组份气体流动的计算中,建立了多化学组份气体的间断分解公式以及任意四边形网格下的Godunov方法的差分格式,提出了处理自由边界的虚相法,应用第二类网格,计算了超音速射流及其冲击问题的几个算例,并且同实验结果进行了比较。     

真实火箭射流冲击流场中激波结构的实验研究

本文采用一种有效的激光-莫瑞光栅干涉系统首次拍摄到真实火箭燃气射流冲击流场的激波结构.解决了长期以来无法拍摄到高温、高速、强火焰光的火箭射流流场图像的问题。利用这一系统,研究了射流冲击流场中激波结构的一些变化规律,发现了一些新的激波结构。较系统地研究了欠膨胀射流冲击各种锥体的激波形态。     

Synthesis, spectroscopic and electrochemical property of an unsymmetrical porphyrin and its Zn compound

<正>In this article,a new 5-(p-maleicaminophenyl)-10,15,20-triphenylporphyrin(H_2P) and relative zinc compound(ZnP) were synthesized and characterized by means of elemental analyses,UV-vis,IR,MS and ~1H NMR spectroscopies.Furthermore,we have investigated the fluorescence spectroscopy of these compounds.The oxidation and reduction properties of the compounds were studied by the cyclic voltarnmetry,the oxidation-reduction potentials were obtained.