掺银的Sm0.5Sr0.5CoO3中温固体氧化物燃料电池复合阴极材料的制备与性能研究

采用硝酸盐分解方法在Sm0.5Sr0.5CoO3 (SSC)中掺入少量的银 (Ag), 形成可用于SOFC的多孔阴极材料 (SSC-Agx). 通过X射线衍射测试确定了材料的物相组成; 用SEM观测了中温电解质Ce0.8Sm0.2O1.9表面涂层电极的微结构; 利用电化学极化曲线和阻抗谱研究了这些材料中低温 (500～800 ℃)电化学性能, 确定掺Ag量和烧结温度对阴极电化学性能的影响. 结果表明, SSC在中温区掺20% Ag时具有最佳的电化学性能, 在600 ℃阴极总阻抗是SSC的1/11, 在750 ℃为SSC的1/4, SSC中掺Ag是提高阴极在中温区电化学性能的有效途径.     

Influence of the texture of chromia catalysts on their activity in synthesis of 2-methylthiophene

The texture of Cr₂O₃-K₂O/Al₂O₃catalysts containing oxides of rare earth elements (REE) was studied. The catalysts are used for the synthesis of 2-methylthiophene by the reaction of H₂S with n-pentane or piperilene. The heterocyclization of n-pentane is a consecutive reaction involving a step of dehydrogenation of initial hydrocarbon. At this step the texture of the catalyst affects the yield of 2-methylthiophene. The yield of 2-methylthiophene obtained from piperilene and I₂S is independent of the catalyst texture.     

Own N-layered integrated molecular orbital and molecular mechanics study of the reaction of OH<Superscript>−</Superscript> with polychlorinated hydrocarbons CH<Subscript>(4−n)</Subscript>Cl<Subscript>n</Subscript> (n=2–4)

The reliability of the two-layer own N-layered integrated molecular orbital and molecular mechanics (ONIOM) method was examined for the S_N2 reaction CH_(4–n)Cl_n+OH^–. In the ONIOM calculation, only the methyl chloride and OH^–were treated at a high level and the effect of polychlorination was taken into account only at a low level. The ONIOM results were compared with the target CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ results obtained by Borisov etal. [(2001) J. Phys. Chem. A 105:7724]. The ONIOM[MP2/aug-cc-pVDZ:B3LYP/6-31+G(d)] was found to reproduce well the target geometry and energy at the MP2/aug-cc-pVDZ level. The single-point improved energetics at the ONIOM[CCSD(T)/aug-cc-pVDZ:MP2/6-31+G(d)] is found to give results nearly as accurate as the target CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ results. The substantially reduced cost, 20% for optimization and 5% for single-point improved energy of the target cost for n=4, as well as small errors suggest that ONIOM is a powerful tool for accurate potential-energy surfaces of the reaction of large polyhalohydrocarbons.     

6-Arylamino-3-methyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines: Novel N-Arylamidine Structures

We propose a method for obtaining derivatives of 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine by alkylation of 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol by substituted -chloroacetanilides, followed by cyclization of the intermediate by phosphorus oxychloride.     

Flow injection system with in-line Winkler's procedure using 16-way valve and spectrofluorimetric determination of dissolved oxygen in environmental waters

Flow injection spectrofluorimetry with in-line Winklers procedure was developed for the dissolved oxygen (DO) determination. 2-Thionaphthol reacted with iodine produced by Winkler’s method to form fluorescence inactive disulfide compound. To automate the process completely, a 5-channel flow system with a newly designed 16-way valve was assembled. The system consisted of a dispersion coil (DC), a precipitate formation coil (PFC), a precipitate dissolving coil (PDC), and extraction coil (EC). A calibration can be constructed by using a standard iodine solution for dissolved oxygen. The calibration graph was linear over the range 1.2×10⁻⁴∼6.0×10⁻⁴ mol l⁻¹ iodine (1.96∼9.80 mg O l⁻¹)). The relative standard deviation (n=6) was below 0.3% for the 4×10⁻⁴ mol l⁻¹ iodine (6.27 mg O l⁻¹) determination. The sample throughput was 12/h.     

The phase diagram of KNO3-KClO3

The binary phase diagram of KNO₃-KClO₃ is studied by means of differential scanning calorimetry (DSC) and high-temperature X-ray diffraction. The limited solid solutions, K(NO₃)_1−x(ClO₃)_x (0<x<0.20) and K(NO₃)_1−x(ClO₃)_x (0.90<x<1.0), were formed in the KNO₃-based solid solutions and KClO₃-based solid solutions phase, respectively. For KNO₃-based solid solutions, KNO₃ ferroelectric phase can be stable from 423 to 223 K as a result of substituting of NO₃ by ClO₃-radicals. The temperatures for solidus and liquidus have been determined based on limited solid solutions. Two models, Henrian solution and regular solution theory for KNO₃-based (α) phase and KClO₃-based (β) phase, respectively, are employed to reproduce solidus and liquidus of the phase diagram. The results are in good agreement with the DSC data. The thermodynamic properties for α and β solid solutions have been derived from an optimization procedure using the experimental data. The calculated phase diagram and optimized thermodynamic parameters are thermodynamically self-consistent.     

Theoretical study of ribonucleotide reductase mechanism-based inhibition by 2'-azido-2'-deoxyribonucleoside 5'-diphosphates

2'-azido-2'-deoxyribonucleoside 5'-diphosphates are mechanism-based inhibitors of Ribonucleotide Reductase. Considerable effort has been made to elucidate their mechanism of inhibition, which is still controversial and not fully understood. Previous studies have detected the formation of a radical intermediate when the inhibitors interact with the enzyme, and several authors have proposed possible structures for this radical. We have conducted a theoretical study of the possible reactions involved, which allowed us to identify the structure of the new radical among the several proposals. A new reactional path is also proposed that is the most kinetically favored to yield this radical and ultimately inactivate the enzyme. The energetic involved in this mechanism, both for radical formation and radical decay, as well as the calculated Hyperfine Coupling Constants for the radical intermediate, are in agreement with the correspondent experimental values. This mechanistic alternative is fully coherent with remaining experimental data.     

Synthesis and properties of substituted 2-methylene-hydrazono-2,3-dihydro-3-benzo[<Emphasis Type="Italic">b</Emphasis>]furanones

The reaction of 2,3-dihydro-2,3-benzo[b]furandione with the triphenylphosphazines of diazo compounds leads to substituted 2-methylenehydrazono-2,3-dihydro-3-benzo[b]furanones, which are hydrolyzed in an acidic medium to the substituted methylenehydrazides of o-hydroxyphenylglyoxalic acid and react with amines to form the products of addition at the activated CH=N bond of the side chain or 2-hydrazono-2,3-dihydro-3-benzo[b]furanone respectively. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 817–822, June, 2007.     

First radical cation salts of 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP) with copper(II) metal complex anions: β-(BDA-TTP)4Cu2Cl6 and (BDA-TTP)2CuCl4

New radical cation salts based on 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene (BDA-TTP) with copper(II) metal complex anions, β-(BDA-TTP)₄Cu₂Cl₆ and (BDA-TTP)₂CuCl₄, were synthesized and structurally characterized. Single crystals were prepared by electrochemical oxidation of BDA-TTP under galvanostatic conditions. X-ray diffraction study demonstrated that the salts have a layered structure, in which the conducting BDA-TTP layers alternate with the [Cu₂Cl₆]²⁻ or [CuCl₄]²⁻ anions. Both salts show the semiconductor-type temperature dependence of the conductivity. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 48–54, January, 2007.     

手性3,5-二甲基-2-芳基-2-吗啉醇盐酸盐的合成及其晶体结构

以(S)-2-氨基丙醇为手性源与α-溴-3-氯苯丙酮反应, (R)-2-氨基丙醇为手性源与6-甲氧基-2-(2-溴丙酰基)萘反应, 分别合成了手性纯化合物(2R,3R,5S)-3,5-二甲基-2-(3-氯苯基)-2-吗啉醇盐酸盐(4a)和(2S,3S,5R)-3,5-二甲基-2-(6-甲氧基-2-萘基)-2-吗啉醇盐酸盐(4b), 利用X射线单晶衍射仪测定了两化合物的晶体结构和两化合物的空间结构, 并初步分析两化合物空间结构, 化合物4a晶体属正交晶系, 空间群为P2₁2₁2, 晶胞参数为: a＝0.8718(2) nm, b＝0.7883(2) nm, c＝2.0247(6) nm, Z＝4, V＝1.3915(7) nm³, D_c＝1.328 g/cm³, F(000)＝584, R₁＝0.0399, wR₂＝0.0797, S＝1.042. 化合物4b晶体属正交晶系, 空间群为P2₁2₁2₁, 晶胞参数为: a＝0.71035 (9) nm, b＝0.77703(10) nm, c＝2.9820(4) nm, Z＝4, V＝1.6318(4) nm³, D_c＝1.318 g/cm³, F(000)＝688, R₁＝0.0520, wR₂＝0.1108, S＝0.994.