甲基肼/四氧化二氮反应化学动力学模型构建及分析

甲基肼(MMH)和四氧化二氮(NTO)是常用的液体火箭发动机推进剂,但目前对其反应机理的研究还十分有限.本文首先构建了一个包含23种组分和20个基元反应的MMH/NTO反应动力学模型;对MMH/NTO自燃着火过程进行的验证计算表明,该机理能够合理地描述MMH/NTO的自燃温升过程,准确预测反应物系统的着火延迟时间及平衡温度,并能合理地反映MMH/NTO反应物系统着火延迟时间对反应初始压力以及氧燃比的依赖关系;通过灵敏度分析方法指出了影响MMH/NTO着火过程的关键反应.模拟分析了在不同压力和氧燃比条件下MMH/NTO系统的自燃温升过程,结果表明,随着压力的升高,系统着火延迟时间变短,平衡温度升高;在一定范围内增大氧燃比,着火延迟时间变长,平衡温度先升高后减小.     

Pole Analysis of Unitarized One Loop χ PT Amplitudes —— A Triple Channel Study

In a previous paper [Commun. Theor. Phys., [arxiv:hep-ph/11081451]], we proposed a method to distin- guish poles of different dynamical origin, in unitarized amplitudes of ππ, K K system. That is based on the observation that “A Breit–Wigner resonance should exhibit two poles on different Riemann sheets which meet each other on the real axis when N_c = ∞”. In this paper, we extend our previous work [Commun. Theor. Phys., [arXiv:hep-ph/11081451]] to the ππ-K K -ηη three channel system. We reconfirm most of the predictions in our previous work [Commun. Theor. Phys., [arxiv:hep-ph/11081451]]. Especially the f₀(980) is of K K molecule nature. Other poles, including the σ, are of Breit–Wigner type.     

Ir/CeO2催化剂的表征和CO氧化性能

采用浸渍法制备了Ir/CeO2催化剂,考察了催化剂的CO氧化活性。随着Ir负载量的增加,Ir/CeO2催化剂的CO氧化活性先上升后下降,当Ir的负载量为1%时,催化剂的活性最高。Ir/CeO2催化剂中Ir以IrO2的形式存在,当低负载量(≤1%)时以高分散形式存在;高负载量(>1%)时以晶相IrO2的形式存在。随着Ir负载量增加,Ir粒子逐渐变大,反应比速率和反应转换频率(TOF)逐渐下降,表明小粒子上具有更高的CO反应活性。同时也发现金属态Ir催化剂的CO氧化活性高于氧化态IrOx催化剂。     

Ir/ZrO2催化剂对甲烷催化燃烧性能的研究

采用浸渍法制备了ZrO₂为载体负载Ir的催化剂(Ir/ZrO₂), 考察了催化剂的CH₄催化燃烧性能. 采用X射线衍射(XRD), 拉曼光谱(Raman), X射线光电子能谱(XPS), 氢气程序升温还原(H₂-TPR)等技术对催化剂的结构和Ir物种的存在形式进行了表征. 结果表明, Ir/ZrO₂催化剂中Ir是以IrO₂形式存在的, Ir/ZrO₂催化剂的CH₄燃烧表观活性随着Ir负载量的增加而提高, 并且催化剂表现出较高的催化活性和良好的反应稳定性. 在低Ir负载量(≤1%)时, CH₄燃烧的转换频率(TOF)随着Ir粒子的增大而提高|然而高Ir负载量(≥1%)时, TOF随着Ir粒子的增大保持不变.     

金属配合物Cd（phen）2（NO3）（NO2）对ZnO光阳极的敏化特性

采用具有紫外光区吸收的金属配合物Cd(phen)2(NO3)(NO2)和N719对ZnO光阳极进行共敏化.结果表明,配合物能够对ZnO光阳极进行共敏化,同时被电解液还原再生,共敏化增加电池对光的吸收,电池光电流密度增加63%,共敏化降低了电池各个界面电阻,有利于电子在界面的传输,电池的光电转换效率提高了37%.     

硅/石墨复合物用作锂离子电池负极材料

以石墨和纳米硅粉为原料, 利用机械球磨的方法制备了硅/石墨复合物, 用作锂离子电池负极材料. 采用XRD, SEM以及电化学测试等手段对材料进行了结构表征和性能测试. 通过球磨不同质量比的硅和石墨, 并对相应的复合物进行充放电测试, 寻找到了硅和石墨的最佳比例, 其值为1∶9. 实验结果表明, 所得材料既具备高于纯纳米硅的循环性能, 又具有比石墨高的可逆容量.     

Multifractal Detrended Cross-Correlation Analysis of agricultural futures markets

We investigated geographically far but temporally correlated China’s and US agricultural futures markets. We found that there exists a power-law cross-correlation between them, and that multifractal features are significant in all the markets. It is very interesting that the geographically far markets show strong cross-correlations and share much of their multifractal structure. Furthermore, we found that for all the agricultural futures markets in our studies, the cross-correlation exponent is less than the averaged generalized Hurst exponents (GHE) when q < 0 and greater than the averaged GHE when q > 0.     

One-dimensional Coordination Polymers Assembled into Two Supramolecular Frameworks with High Stability

The dual ligand system of V-shaped 5-(4-carboxy-2-nitrophenoxy)-isophthalic acid(Hcn-H2ipa) and dipyridy-type molecules produces two new coordination polymers: {[Ni(cn-Hipa)(bpa)(H2O)3]·1.5H2O}n 1 and {[Cu(Hcn-ipa)(ppe)2]}n 2(bpa = 1,2-bis(4-pyridyl)ethane, and ppe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene). Two complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, IR, and thermogravimetric analysis(TGA). Complex 1 is of monoclinic system, space group C2 with a = 25.936(3), b = 7.6100(10), c = 16.558(2), β = 105.9470(10)°, V = 3142.4(7) ?3, Dc = 1.415 g/cm3, Mr = 669.23, Z = 4, F(000) = 1388, μ = 0.687 mm-1, the final R = 0.0397 and w R = 0.0967 for 12070 observed reflections with I 2σ(I). Complex 2 belongs to the triclinic system, space group P1 with a = 10.165(5), b = 14.946(7), c = 15.506(11) ?, α = 106.461(7), β = 102.454(8), γ = 107.861(5)°, V = 2029(2) ?3, Dc = 1.266 g/cm3, Mr = 773.20, Z = 2, F(000) = 794, μ = 0.595 mm-1, the final R = 0.0538 and w R = 0.1378 for 15488 observed reflections with I 2σ(I). Two complexes show that the 1D polymeric chains are cohered together by extensive H-bonds to complete stable supramolecular microporous frameworks.