Kinetics and mechanism of the reactions of CH3CO and CH3C(O)CH2 radicals with O2. Low-pressure discharge flow experiments and quantum chemical computations

The reactions CH(3)CO + O(2)--> products (1), CH(3)CO + O(2)--> OH +other products (1b) and CH(3)C(O)CH(2) + O(2)--> products (2) have been studied in isothermal discharge flow reactors with laser induced fluorescence monitoring of OH and CH(3)C(O)CH(2) radicals. The experiments have been performed at overall pressures between 1.33 and 10.91 mbar of helium and 298 +/- 1 K reaction temperature. OH formation has been found to be the dominant reaction channel for CH(3)CO + O(2): the branching ratio, Gamma(1b) = k(1b)/k(1), is close to unity at around 1 mbar, but decreases rapidly with increasing pressure. The rate constant of the overall reaction, k(2), has been found to be pressure dependent: the fall-off behaviour has been analysed in comparison with reported data. Electronic structure calculations have confirmed that at room temperature the reaction of CH(3)C(O)CH(2) with O(2) is essentially a recombination-type process. At high temperatures, the further reactions of the acetonyl-peroxyl adduct may yield OH radicals, but the most probable channel seems to be the O(2)-catalysed keto-enol transformation of acetonyl. Implications of the results for atmospheric modelling studies have been discussed.     

Crystal Structure of the 1:2 Stoichiometric Nd: [α-SiW_(11)O_(39)]~(8-): K_5Na_5H_3[Nd(α-SiW_(11)O_(39))_2]·6H_2O

Single-crystal X-ray structural analysis of K5Na5H3[Nd(α-SiW11O39)2]·6H2O (triclinic, space group P1, a = 13.7738(10), b = 19.722(2), c = 20.6647(15) , α = 111.0090(10), β = 105.1740(10), γ = 98.6870(10)o, Z = 2, V = 4867.2(8), Mr = 5914.40, Dc = 4.026, μ = 26.754 mm-1, F(000) = 5076, R = 0.0750 and wR = 0.2077) reveals that two [α-SiW11O39]8- moieties are connected through one Nd atom which is in a square antiprismatic coordination environment by eight oxygen atoms from two [α-SiW11O391]8- moieties. The Nd(Ⅲ ) ion is substituted for a [WO]4+ unit in the "cap" region of the tungsten-oxygen framework of the parent Keggin ion. Disordered Na+ cations and water molecules reside outside these channels, leaving empty pores with an intersecting slot (13 × 10 ).     

Analysis of tensides in complex samples with comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry

Multidimensional gas-chromatographical analysis of various tensides of natural or synthetic origin in cosmetic products is demonstrated. Comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry allows the qualitative and quantitative determination of alkyl polyglucosides (AG), fatty alcohol ethoxylates (FAEO), fatty alcohol sulfates (FAS), fatty alcohol ether sulfates (FAES) and cocamidopropyl betaines (CAPB) in shower gel and cleaning agents. The samples were aliquoted in two parts. The first part was silylated, diluted and analysed; then, in order to detect anionic tensides (FAES, FAS) too, the second aliquot was hydrolysed before being silylated for analysis. Because of their amphoteric character, the betaines can only be analysed by gas chromatography after thermal decomposition in the injector, which leads to the corresponding amidoamines among other products.     

Crystal Structure of 〔PrAl(CF_3COO)_2(CF_3CHOO)(C_2H_5)_2(C_4H_8O)_2〕_2

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The Molecular Structure and Potential Energy Function for Ne-HF System

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Dumb-bell Structures of Nonstoichiometric La（Ni, Sn）5＋x Alloys and Their Relationships with the Preparation Methods

Crystal structures of nonstoichiometric La(Ni, Sn)5 x (x = 0.1～0.4) alloysprepared by different methods were investigated by using powder X-ray diffraction and Rietveldrefinement analysis. Space group of this type of alloys belongs to P6/mmm, in which Sn onlyoccupies the 3g sites. It has been demonstrated that some of the la sites of the nonstoichiometricalloy are replaced by the Ni-Ni dumb-bells which have a strong correlation with the anisotropicthermal parameter B33. The preparation methods have an effect on the number of dumb-bells thatcan substitute the l a sites. It was found that the annealed alloys have more Ni-Ni dumb-bells inthe structure than the rapid solidified and as-cast alloys have while still keep good crystallinity.     

四氯合钯(II)喹诺酮配合物的合成及与DNA的作用和抗增殖活性

在酸性条件下, 分别合成了四氯合钯(II)离子与2种喹诺酮(诺氟沙星, NFLX＝C16H18N3O3F; 环丙沙星, CPLX＝C17H18N3O3F)离子形成的配合物(NFLXH)2[PdCl4]•2H2O (1)和(CPLXH)2[PdCl4]•2H2O (2). 用元素分析、IR、UV以及摩尔电导测定等方法对其进行了表征. 配合物1的晶体结构经X射线单晶衍射确定, 结构参数: 三斜晶系, P-1空间群, a＝0.84561(17) nm, b＝0.94191(19) nm, c＝1.2832(3) nm; α＝111.26(3)°, β＝97.23(3)°, g＝96.38(3)°, V＝0.9312(4) nm3, Z＝1, 最后吻合因子R＝0.040, wR＝0.088. 利用紫外光谱法、荧光光谱法对配合物与小牛胸腺DNA (ct-DNA)的作用进行了研究, 研究表明, 配合物对DNA的作用模式为插入作用, 与DNA的结合常数Kb分别为: Kb(1)＝2.06×104, Kb(2)＝2.43×104. 其后测试了配合物对体外肿瘤细胞的抗增殖活性. 经采用四甲基偶氮唑蓝分析法(MTT法)测试后发现配合物1和2对人肺腺癌A549细胞、人原髓细胞白血病HL-60细胞的增殖抑制作用显著强于相应的喹诺酮分子本身, 其中配合物2对人肺腺癌A549细胞增殖有明显的抑制作用, 抑制率可高达(95.4±3.7)%, 半数抑制浓度(IC50, 72 h)为(124.5±10.3) μmol•L－1.     

AlF3包覆LiNi0.45Mn0.45Co0.10O2锂离子电池正极材料的结构表征和 电化学性能研究

通过共沉淀与固相反应法制备层状的LiNi0.45Mn0.45Co0.10O2, 并利用X射线衍射(XRD)和电子扫描显微镜(SEM)测定材料的结构和形貌. 在2.5～4.5 V范围内, 以0.1 C (28 mA•g－1)放电, LiNi0.45Mn0.45Co0.10O2正极材料的起始放电容量达到167.2 mAh•g－1, 但循环性能较差. 当采用AlF3包覆后, 材料的循环性能得到明显改善. 利用电化学阻抗谱(EIS)技术探索AlF3包覆对正极材料的电化学性能改善机理, 实验结果表明: AlF3包覆层能够阻止电解液对正极材料的溶解和侵蚀, 稳定其层状结构, 同时降低了电极界面阻抗. 因此AlF3包覆技术是一种改善LiNi0.45Mn0.45Co0.10O2材料电化学性能的有效方法和工具.     

人面果树皮中口 山 酮 化合物及其DPPH自由基的清除活性

从人面果乙酸乙酯提取物中分离出5个新的口 山 酮 化合物garcinenone A (1), B (3), C (4), D (7) and E (8)和7个已知化合物,其结构经过波谱技术,特别是2D-NMR技术来鉴定。Jacareubin (2), 1,4,6-trihydroxy-5-methoxy-7-(3-methyl-2-buteny1)xanthone (6), subeliptenone B (11) 和symphoxanthone (12)为首次从该植物中分离出来。在DPPH自由基的清除活性实验中,所有的化合物都显示抗氧化活性,其IC50的值在 6.0-23.2 mM。结果表明人面果是潜在的有前景的天然抗氧化剂。