广义超立方体网络中一类容错路由选择

证明了n-维广义超立方体网络Q(m1,m2,…,mn)中,任意两个节点x和y之间存在长度均不超过H(x,y)+2的m1+m2+…+mn-n条内点不交的路由,其中有H(x,y)条长度不超过H(x,y),此处H(x,y)表示x到y的汉明距离.并在此基础上讨论了广义超立方体网络的容错路由问题.证明了即使无效点很多,但只要存在某个(n-1)-维广义超子立方体中无效节点较少,则该n-维广义超立方体中的任意两个有效节点之间可以找到最优路由或接近最优路由的有效路由.     

Evidence for direct observation by Mössbauer spectroscopy of surface tin atoms in platinum–tin particles

The diamond-bearing gravels found along South Africa's West Coast are being beneficiated by means of dense medium separation (DMS) to reclaim the alluvial diamonds. Granular ferrosilicon (Fe–Si) is used as the DMS material and at the end of each operation the Fe–Si is reclaimed from the process stream using a magnetic separator and is then recycled but losses of Fe–Si due to attrition, adhesion to the separation products, density changes and changes to the magnetic properties can occur. The gravel obtained from the mining operation is washed and screened before heavy mineral separation. The concentrate, tailings and Fe–Si samples were investigated by means of SEM and Mössbauer spectroscopy to determine where changes to the Fe–Si, or contamination could occur. The composition of the Fe–Si was determined to be Fe (76.1 at.%), Si (20.3 at.%), Mn (1.5 at.%), Al (1.5 at.%) and Cr (0.6 at.%) resulting in a more or less ordered DO₃ phase with a calculated composition of Fe₃Si for this Fe–Si, consistent with the Mössbauer results where two sextets with hyperfine magnetic fields of 18.6 T and 28.4 T were observed. After DMS, magnetite and ilmenite, the minerals found in the gravel, were still present in the concentrate. In the tailings virtually no magnetite or ilmenite was found and only a doublet, identified as an oxihydroxide, due to the abrasion of the Fe–Si, was found. After magnetic separation, to wash and clean the Fe–Si for re-use, it was found that magnetite and ilmenite were still present in the Fe–Si, which results in a change in density of the Fe–Si, resulting in a higher density and loss of valuable diamonds.     

一个哈密顿系统正则动量的软模振荡

本文进一步研究了以前提出的哈密顿系统,说明非线性振子的实振幅具有的极限圈运动,由于另一类模式耦合扰动,引起振子的线性频率重新激发,而失稳到二维环。据此,分析了有关的实验及理论研究,推断流体力学矩方程之间的耦合,可能在显示Ruelle-Takens途径上起了关键作用,同时猜想向湍流转变的图象是轨迹被吸引在两个二维环上不断调节的运动。     

CoPc在八面沸石笼中的原位合成及性能研究

采用苯酐－尿素路线，对CoPc金属配合物在八面沸石超笼中原位合成进行了考察，并采用多种物化手段和催化反应对所制备的CoPcY进行了详细的表征。结果表明，该制备路线是一简便有效的合成路线，采用该路线可在八面沸石超笼中原位合成CoPc金属配合物并将之固定于八面沸石中。在该制备方法中合成温度、离子交换所采用的盐类型及催化剂对CoPc金属配合物在八面沸石超笼中的合成及所制备的CoPcY在环己烷氧化反应中的催化性能有很大的影响，其中180 ℃为最佳合成温度，氯化钴较适合作为交换的盐类。在八面沸石超笼中原位合成的CoPc金属配合物在温和的反应条件下对环己烷氧化具有良好催化活性，转化数TON最高可达5 000以上。     

Synthesis, structure and properties of new chain cuprates, Na3Cu2O4 and Na8Cu5O10

Na₃Cu₂O₄ and Na₈Cu₅O₁₀ were prepared via the azide/nitrate route from stoichiometric mixtures of the precursors CuO, NaN₃ and NaNO₃. Single crystals have been grown by subsequent annealing of the as prepared powders at 500 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structures (Na₃Cu₂O₄: P2₁/n, Z=4, a=5.7046(2), b=11.0591(4), c=8.0261(3) Å, β=108.389(1)°, 2516 independent reflections, R₁(all)=0.0813, wR₂ (all)=0.1223; Na₈Cu₅O₁₀: Cm, Z=2, a=8.228(1), b=13.929(2), , β=111.718(2)°, 2949 independent reflections, R₁(all)=0.0349, wR₂ (all)=0.0850), the main feature of both crystal structures are CuO₂ chains built up from planar, edge-sharing CuO₄ squares. From the analysis of the Cu-O bond lengths, the valence states of either +2 or +3 can be unambiguously assigned to each copper atom. In Na₃Cu₂O₄ these ions alternate in the chains, in Na₈Cu₅O₁₀ the periodically repeated part consists of five atoms according to Cu^II-Cu^II-Cu^III-Cu^II-Cu^III. The magnetic susceptibilities show the dominance of antiferromagnetic interactions. At high temperatures the compounds exhibit Curie-Weiss behaviour (Na₃Cu₂O₄: , , Na₈Cu₅O₁₀: , , magnetic moments per divalent copper ion). Antiferromagmetic ordering is observed to occur in these compounds below 13 K (Na₃Cu₂O₄) and 24 K (Na₈Cu₅O₁₀).     

Leaching of the Anthraquinone Dye Solvent Blue 59 Incorporated into Organically Modified Silica Xerogels

The effects of preparation method and precursor composition on the leaching behavior of the anthraquinone dye Solvent Blue 59 incorporated into silica based xerogels have been studied. Xerogels were prepared under acidic conditions from mixtures of 20 mol% of organically modified silicon alkoxides, R–Si(OR)3, in Si(OR)4 (R = methyl or ethyl, R = methyl, vinyl, phenyl). The dye was added at the beginning of the sol-gel reaction. The reaction was carried out by either hydrolysis under acidic conditions or acidolysis by formic acid. The dye incorporated was leached with refluxing ethanol using a Soxhlet extraction procedure to simulate the long-term stability of the samples prepared. With increasing size of organic substituent (methyl < vinyl < phenyl), the amount of dye leached decreases. Results from nitrogen adsorption experiments show that all samples characterized have about the same average pore diameter, but they differ in total pore volume and BET surface area. With increasing size of the organic residue, the pore volume decreases by an order of magnitude. Therefore, it is concluded that the microstructure of the xerogels prepared determines the retention behavior of dyes incorporated during the sol-gel reaction.     

PYRIDINATION OF POLY（VINYL CHLORIDE） via A HOMOLYTIC PATHWAY

PVC was subjected to a chemical modification aiming at replacing the chlorine atoms by pyridine groups via a homolytic route. Pyridine groups were peculiarly affixed to the PVC matrix via a carbon-carbon bond rather than a carbon-nitrogen one. PVC was first iodinated using the Conant-Finkelstein reaction, followed by the application of the homolytic conditions of Minisci to generate pyridinated PVC with a varying degree of substitution. The extent of substitution was not high; the reaction on 30% iodinated PVC afforded a degree of modification no greater than 3%.     

制备参数影响ZrO2气凝胶结构特性的机理

探讨了胶凝顺序、老化介质和氨水溶度影响样品结构的内在机理，结果表明，ＺｒＯ２样品形貌的不同是由于或胶凝顺序不同而引起的水解和缩聚的进程不同，或老化介质不同而引起的老化机理不同所致。氨水浓度的影响一方面与粒子活动体积有关，一方面与氨水中的水抑制缩聚有关。且经过老化后使其影响更加明显。     

新型锂离子电池CaSnO3负极材料的湿化学制备与电化学性能

采用湿化学方法合成了具有钙钛矿结构的CaSnO₃，将其作为锂离子电池的负极活性物质，研究了其电化学性能。结果表明，湿化学方法制备的锡酸钙，粒度分布集中、平均粒径在500 nm左右，在0～1.0 V之间以0.1 C倍率充放电时，其可逆容量达到469 mAh·g^-1，而且循环性能良好。经80次循环后的容量衰减率只有0.57%。从首次放电容量和可逆容量来看，锡酸钙的储锂机制与锡基氧化物材料相似，即:首先是结构的还原并形成金属锡；然后金属锡与锂发生可逆的合金化与去合金化过程。锡酸钙的可逆容量、循环性能都比文献报道的块状锡氧化物或者是无定型锡基复合氧化物好，这说明钙钛矿结构和钙离子的存在可能对改善锡基负极材料的性能是有益的。     

Solvothermal Route to Prepare the Metastable Phase 3c-Fe7S8 with Hexagonal Platelet Morphology

The metastable phase 3c-Fe7S8 with the hexagonal platelct morphology has been prepared by using solvothermal route.The product was characterized by mcans of X-ray powder diffraction(XRD) and transmission electron microscopy (TEM) and X-ray photoelectron speetra (XPS).The experiment results show that the as-prepared Fe7S8 is a metastable phase with the hexagonal platelet morphology.