超临界流体干燥过程的分析

以ZrOCl2•8H2O为原料，采用超临界流体干燥（SCFD）法，在短时间内制备出大孔体积高比表面ZrO2气凝胶超细粉．该法具有良好的稳定性和可靠性．建立了醇凝胶中液相含水量的分析方法，为产品质量控制及确认体系是否处于超临界状态提供了依据．对抽提后的溶剂分析表明，SCFD过程是一物理过程．对水的抽提干燥过程亦进行了初步的理论探讨．     

甲烷氧化偶联Na2WO4-Mn/SiO2催化剂热效应的研究

采用固定床微型反应装置,研究了甲烷氧化偶联反应过程中Na2WO4-Mn/S iO2催化剂床层的热效应和催化性能的关系,考察了反应炉温、CH4/O2比和反应气体空速对催化剂床层热点分布的影响.研究结果表明,甲烷氧化偶联催化剂床层的热效应强烈依赖于反应条件.反应炉温越高,CH4/O2比越低,反应气体空速越大,催化剂床层的热点温度越高.结合催化性能和热效应关系的研究,为优化甲烷氧化偶联的反应操作提供了实验依据.     

Dielectric properties and frequency response of self-assembled monolayers of alkanethiols

This paper presents dielectric properties of alkanethiol self-assembled monolayers (SAMs) under an ac electric field. Using a Hg-SAM/SAM-Hg junction, we measured the ac impedance of alkanethiol SAMs using a sinusoidal perturbation of 30 mV (peak-to-peak) with frequency ranging from 1 Hz to 1 MHz at zero bias. Semicircles at higher frequencies and at middle frequencies along with Warburg lines at lower frequencies were observed in complex plane impedance plots, that is, Nyquist plots. The frequency response of SAMs was analyzed by modeling the junction using an equivalent circuit and fitting the Nyquist plots. The semicircles at higher frequencies are attributed to the effect of the SAM/SAM interfaces, and the ones at middle frequencies are attributed to the effect of alkanethiol SAMs. The comparison in the plots of the imaginary part of the impedance Z against frequency for the bare Hg electrodes (in pure ethanal) and the SAM-covered Hg electrodes (in alkanethiol solution) supports the analysis. The Warburg lines are attributed to a certain ionic impurity. The dielectric loss spectra are further analyzed. Chain-length-dependent peaks, which correspond to different relaxation mechanisms, at higher frequencies and middle frequencies were observed in the spectra of the dissipation factor (tan delta vs frequency). The peaks move to small frequency with the increase of chain length of alkanethiols. Using a correlation of peak position with the chain length, we then derived active energies of 39-99 meV for alkanethiol SAMs of C7-C18 under an ac electric field.     

配体形状对多吡啶铜(Ⅱ)配合物与DNA作用的影响

合成了一系列含有平面配体的Cu(Ⅱ)多吡啶配合物[Cu(IP)₂]²⁺、[Cu(PIP)₂]²⁺、[Cu(DPPZ)₂]²⁺和[Cu(HPIP)₂]²⁺，用吸收光谱、CD光谱和粘度等方法研究了这些配合物与小牛胸腺DNA的作用。结果表明配体上的取代基及配体的平面性对这些四面体配合物与DNA的结合强弱产生一定的影响。[Cu(DPPZ)₂]²⁺与DNA的结合较强，而[Cu(HPIP)₂]²⁺与DNA的结合较弱。CD光谱显示配合物[Cu(DPPZ)₂]²⁺、[Cu(PIP)₂]²⁺和[Cu(HPIP)₂]²⁺的加入会导致DNA的CD光谱减弱。而[Cu(IP)₂]²⁺的加入则会使DNA的CD光谱增强。同时，[Cu(IP)₂]²⁺与DNA结合后，还会引起一定程度的DNA构型转换，即DNA从B型转换成Z型。     

芴取代的有机膦化合物的合成及发光性能

合成了以芴为取代基，P原子为核的一类新型有机膦化合物．此类化合物的HOMO值在-5．35～-5．24eV之间．在二氯甲烷中的最大紫外吸收光谱峰值在313～351nm之间，荧光光谱峰值在334～397nm之间．利用此类小分子与纯聚芴进行掺杂，制作了有机电致发光器件．低HOMO值有机膦化合物的引入有效地降低了聚芴发光器件的开启电压，提高了器件的发光效率．     

Preparation ,Structural Characterization and Luminescent Property of Binucleasr Silver（Ⅰ）Complex Formed by Benzotriazole and 1—Hydroxymethyl Benzotriazole

Dinuclear silver (I) six‐membered ring complex [Ag₂ (bta)₂ ‐(hmbta)₂] (ClO₄)₂ (3) has been synthesized by the reaction of benzotriazole (bta) (1) and 1‐hydroxymethyl benzotriazole (hmbta) (2) with Ag (CH₃CN)₄ClO₄. The structures of compound 2 and Complex 3 have been studied by single crystal X‐ray diffraction analysis. The change of luminescent intensity of 1, 2 and 3 was reported. Compound 2 crystallizes in the monoclinic system with space group P2 (1)/c, a = 0.7655 (10) nm, b = 1.0126 (14) nm, c =0.9502 (13) nm, β = 95.07 (2)°, V = 0.7337 (17) nm³ and Z = 4. Complex 3 crystallizes in the triclinic system with space group P1, a = 0.73611 (18) nm, b = 0.9152 (2) nm, c = 1.2277 (3) nm, β = 87.170 (5)°, V = 0.8221 (3) nm³ and Z = 1. The main structural feature of complex 3 is a symmetric dinuclear six‐membered ring formed by two silver (I) atoms and four N‐atoms from two benzotriazoles. The second structural feature of complex 3 is the τ‐τ stacking interaction between two adjacent molecular planes, which forms the two‐dimentional layer structure. Besides, compared with 2, the luminescent intensity of complex 3 shows a remarkable enhancement.     

负载型非晶态Cu/SiO2催化剂的非晶性质

以超细ＳｉＯ２为载体，用ＫＢＨ４还原Ｃｕ＾２＋盐溶液制备了非负载型Ｃｕ和负载型Ｃｕ／ＳｉＯ２催化剂，ＸＲＤ，ＴＥＭ和电子衍射分析结果表明，负载型Ｃｕ／ＳｉＯ２为完全非晶态，而非负载型Ｃｕ中存在着少量晶态Ｃｕ，ＤＳＣ结果表明，非晶态Ｃｕ／ＳｉＯ２的热稳定性明显高于非负载型Ｃｕ，说明超细ＳｉＯ２具有稳定非晶结构的作用，ＸＰＳ结果表明，还原产物中的铜原子呈Ｃｕ状态，ＩＣＰ分析结果表明，样品中的Ｂ含量均低     

Self-assembled multivalent vancomycin on cell surfaces against vancomycin-resistant enterococci (VRE)

A vancomycin (Van) derivative self-assembles in a phosphate buffer as a divalent Van and on cell surfaces as a multivalent Van, which offers potent activity against VRE.     

Crystal Structure of (6S,9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-17-methylmorphinan-4,6-diol

1 INTRODUCTION (9S,13R,14S)-7,8-Didehydro-3,7-dimethoxy-4-hydroxy-17-methylmorphinan-6-one I is an impor- tant natural product that was used to ease pain, decrease blood pressure and diminish inflammation. In order to study the stereochemistry of the reduction of I with potassium boronhydride, the crystal structure of the title compound II was determined by X-ray diffraction method. 2 EXPERIMENTAL 2. 1 Instrument The melting point was measured on a Yanagimoto MP-500 apparatus…     

弯曲铝合金方管的轴压性能试验研究

为研究带初弯曲度铝合金方管的轴压承载力,完成了8个试件的轴压稳定性试验,并建立了与试验条件一致的有限元模型。通过对比试验和有限元分析结果验证了有限元模型的可靠性。结果表明,带有较大初弯曲度铝合金方管的破坏模式为整体弯曲失稳。最后,根据有限元分析结果拟合得到较大初弯曲度铝合金方管的整体稳定系数计算式,并将拟合计算式结果和数值分析结果及试验结果进行对比,验证了计算式的正确性。