Decay kinetics of benzophenone oxide in the liquid phase

The kinetics of self-termination of benzophenone oxide (BPO) in the liquid phase was studied by flash photolysis. The extinction coefficient of BPO (ε) was found to be virtually independent of the solvent nature, ε=(1.9±0.1)·10³ L mol⁻¹ cm⁻¹. The rate constant of the BPO self-temination increases from 1.8·10⁷ (MeCN) and 7.4·10⁷ (C₆H₆) to 1.5·10⁹ (n-decane) and 2.0·10⁹ L mol⁻¹ s⁻¹ (n-pentane) at 293±2 K. Solvation of BPO promotes a polar state of the molecule in MeCN and C₆H₆. In nonpolar hydrocarbons, a great contribution is made by the biradical structure resulting in an increase in the rate constant and a shift of the absorption maximum to the long-wave region (from 410 nm in MeCN to 425 nm inn-pentane). In solutions of benzene and acetonitrile, benzophenone oxide reacts with the parent diazo compound with a rate constant of (2–4)·10⁵ L mol⁻¹ s⁻¹ (293±2 K) along with the self-termination. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1329–1332, July, 1998.     

钙钛矿结构在CO还原SO2催化脱硫中的作用

通过对钴和镧的单一氧化物、混合氧化物及具有钙钛矿结构的复合氧化物（ＬａＣｏＯ３等）上ＣＯ还原ＳＯ２脱硫反应的活性以及钴镧氧化物在反应条件下活化过程的考察，指出钙钛矿结构促进了活性晶相ＬａＯ２Ｓ和ＣｏＳ２的生成，增强了钴和镧在活化硫化及脱硫反应中的协同效应。     

锰基催化剂上CO2加氢反应性能的研究

研究了Ｍｎ基催化上ＣＯ２的加氢反应性能，结果表明：ＣＯ２活化吸附量的增加有利于ＣＯ２转化率的提高。Ｍｎ具有较好的ＣＯ２加氢生成ＣＯ的催化活性，ＣｕＯ，Ｆｅ２Ｏ３的ＺｎＯ的加入使催化剂活性得到进一步的提高；ＮｉＯ的加入增加了催化剂的Ｈ２活化吸附量，从而使催化剂对ＣＨ４的选择性得到提高，同时使ＣＯ２的转化率与Ｎｉ／γ－Ａｌ２Ｏ３相比略有下降。     

Archetypical Conductive Polymer Structure for Specific Interaction with Proteins

A series of 2,4-dinitrophenyl (DNP) functionalized polypyrrole terpolymers, capable of specific binding to IgE antibodies (proteins), have been synthesized using oxidizing initiator, ammonium persulfate and were characterized by ¹H-NMR, IR, DSC, Light Scattering etc. The terpolymers were composed of monomers and macromonomers: monomer (pyrrole), macromonomer A (pyrrole with pendant ethylene glycol) and macromonomer B (pyrrole with pendant DNP) with specific functionality of conductance, processiblity and binding, respectively. The terpolymers are found to be semiconductive, (5 × 10^?6 S cm^?1) by itself without the addition of doping agents. Molecular dynamics simulation of terpolymer shows that the DNP-(2,4-dinitrophenyl) functional group extends out from the polymer backbone and thus, is available for binding. The DNP functional groups on the terpolymer achieve steady state binding with anti-DNP IgE proteins at nanomolar concentrations in solution. The terpolymer was blended with sulfonated polystyrene and processed in fibers which exhibited effective specific binding to fluorescently tagged IgE proteins and therefore, possessed the potential to be an active component in biosensor.     

La掺杂在BiOBr光催化剂氧化和还原性能调控中的不同作用

同时使用有机溴源十六烷基三甲基溴化铵（CTAB）和无机溴源NaBr,通过溶剂热法合成了具有层状类囊体结构的La掺杂BiOBr光催化剂。通过第一性原理（DFT）计算了La掺杂对BiOBr能带结构的影响。采用X射线衍射、扫描电子显微镜、透射电子显微镜、X射线光电子能谱及荧光光谱对催化剂进行了表征。在可见光照射下,以光催化降解酸性橙Ⅱ和氨氮废水测试了La-BiOBr的氧化性能;以亚甲基蓝为还原指示剂,测试了La-BiOBr的还原性能。研究表明,La的掺杂可以促进晶粒的堆积。而且BiOBr的氧化性能和还原性能分别被促进和抑制,即La的掺杂促进了BiOBr光催化剂的氧化性能,抑制了其还原性能。     

Nanoscale Perovskites as Catalysts and Supports for Direct Methanol Fuel Cells

With the ultimate goal of simultaneously finding cost-effective, more earth-abundant, and high-performance alternatives to commercial Pt/Pd-based catalysts for electrocatalysis, this review article highlights advances in the use of perovskite metal oxides as both catalysts and catalyst supports towards the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) within a direct methanol fuel cell (DMFC) configuration. Specifically, perovskite metal oxides are promising as versatile functional replacements for conventional platinum-group metals, in part because of their excellent ionic conductivity, overall resistance to corrosion, good proton-transport properties, and potential for interesting acidic surface chemistry, all of which contribute to their high activity and reasonable stability, especially within an alkaline electrolytic environment.     

甲烷在金属铁及氧化铁表面还原NO的研究

在程序控温电加热水平陶瓷管反应器、N₂气氛和模拟烟气气氛及300~1 100℃时,对甲烷在金属铁及其氧化铁表面还原NO的特性进行了实验研究。为使甲烷在脱硝反应后完全燃尽以及脱硝反应过程生成的CO等中间产物完全燃尽,在第一段加热炉后串联了第二段加热炉,补充氧气,实现燃尽。结果表明,甲烷在金属铁及氧化铁表面能够高效地还原NO。在N₂气氛中,在900℃以上温度范围内甲烷在金属铁表面的脱硝效率超过95%,与甲烷在氧化铁表面的脱硝效率差别很小。在模拟烟气条件下,当过量空气系数小于1.0时,在900℃以上时,甲烷在金属铁和氧化铁表面的脱硝效率都能超过90%,且未燃尽和燃尽两种条件下NO的还原率相差不大。NO同时通过金属铁的直接还原和甲烷的再燃还原两种反应机理脱除。而甲烷则通过还原氧化铁为金属铁,从而使金属铁直接还原NO可持续进行。同时,甲烷再燃反应的中间产物HCN/NH₃等被氧化铁还原,从而使燃尽后的脱硝效率不下降。研究结果表明,甲烷和金属铁或氧化铁在富燃料条件下可有效地还原NO。     

Synthesis, Characterization and Humidity Sensitive Properties of Nanocrystalline LaCoxFe1-xO3

The nanocrystalline LaCo_xFe_1-xO₃ with different concentrations of Co was prepared by polyethylene glycol (PEG) sol-gel method and characterized by differential thermal analysis and thermal gravimetric analysis (DTA-TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). It was found that the crystal structure of perovskite-type could be obtained at 600 °C, and the concentration of Co had significant effects on the solid-state reaction and the average particle size of the obtained nanocrystals. Furthermore, the humidity-sensitive properties of nanocrystalline LaCo_xFe_1-xO₃ were investigated, and it was found that LaCo_0.3Fe_0.7O₃ exhibited higher sensitivity to humidity compared with other samples. The addition of Na₂CO₃ improved the humidity-sensitive properties of this sample, and made its response to humidity good in the whole humidity range of 11%-95% relative humidity (RH).     

Effect of oxygen non-stoichiometry on the structural and magnetotransport properties of LaMn0.85Cr0.15O3+δ

Thermogravimetry, X-ray diffraction (XRD), d.c. magnetization, high-temperature susceptibility and electrical resistivity measurements were performed for LaMn_0.85Cr_0.15O_3+δ perovskites with accurate control of the oxygen content (0?δ?0.11). For 0?δ<0.09, three orthorhombic structures (Pnma) are found: for 0?δ<0.045, the O′ phase (b/√2<c<a), for 0.045?δ<0.06, the O″ (b/√2<a<c) and for 0.06?δ<0.09, the O^? (a<b/√2<c). For 0.09?δ?0.11, a rhombohedral symmetry coexists with O^? in a biphasic field. Magnetic measurements revealed the ferromagnetic interactions (FM) character of the Mn³⁺-O-Cr³⁺ interaction, but also the intricate magnetic phase diagram due to the presence of multiple interactions (Mn^3+,4+-O-Mn^3+,4+, Cr³⁺-O-Mn³⁺, etc.). The comparison of the results for LaMn_0.85Cr_0.15O_3+δ with those of LaMn_0.9Cr_0.1O_3+δ allows discuss the role of Cr³⁺ on the structural, magnetic and magnetotransport properties of the LaMn_1−xCr_xO_3+δ perovskites.     

Synthesis and study of the crystallographic and magnetic structure of DyFeMnO5: A new ferrimagnetic oxide

The title oxide has been obtained by replacing Mn³⁺ by Fe³⁺ in the parent oxide DyMn₂O₅. The crystallographic and magnetic structures have been analysed from neutron powder diffraction (NPD) data, in complement with susceptibility and magnetic measurements. DyFeMnO₅ is orthorhombic, belonging to the Pbam space group as the parent compound. The crystal structure contains infinite chains of edge-sharing Mn⁴⁺O₆ octahedra, interconnected by dimer units of Fe³⁺O₅ square pyramids. There is a certain antisite disorder in the crystal structure, with 8.0% of the Mn⁴⁺ sites occupied by Fe cations, and 8.2% of the Fe³⁺ positions occupied by Mn³⁺ cations. The magnetization measurements show that DyFeMnO₅ presents magnetic order below T_C≈178 K; a study of the magnetic structure from the low-temperature NPD patterns indicates an antiferromagnetic coupling of the Mn⁴⁺ and Fe³⁺ spins, with the polarization of the Dy³⁺ magnetic moments parallel to the those of the Fe sublattice.