按序列分布混沌与拓扑混合

本文讨论了按序列分布混沌与拓扑混合的关系,并证明了:若X为至少两点的可分局部紧致度量空间,连续映射f:X→X是拓扑混合的,则对于任一正整数递增序列{mi},存在X的c-稠密Fσ子集D是f按{mi}的某子序列的分布混沌集.     

亚纯函数的Valiron亏函数

对于开平面内有穷级的超越亚纯函数f(z),本文主要讨论其Valiron亏函数问题,得到f(z)的Valiron亏函数的F_δ-集合必为μ-集合的结论,去掉了陈怀惠等对f(z)的极点的要求。最后指出对于无穷级的情形,也有相应的结论。     

Ferric Phosphate Hydroxide Microstructures Affect Their Magnetic Properties

Uniformly sized and shape-controlled nanoparticles are important due to their applications in catalysis, electrochemistry, ion exchange, molecular adsorption, and electronics. Several ferric phosphate hydroxide (Fe₄(OH)₃(PO₄)₃) microstructures were successfully prepared under hydrothermal conditions. Using controlled variations in the reaction conditions, such as reaction time, temperature, and amount of hexadecyltrimethylammonium bromide (CTAB), the crystals can be grown as almost perfect hyperbranched microcrystals at 180 °C (without CTAB) or relatively monodisperse particles at 220 °C (with CTAB). The large hyperbranched structure of Fe₄(OH)₃(PO₄)₃ with a size of ∼19 μm forms with the “fractal growth rule” and shows many branches. More importantly, the magnetic properties of these materials are directly correlated to their size and micro/nanostructure morphology. Interestingly, the blocking temperature (T_B) shows a dependence on size and shape, and a smaller size resulted in a lower T_B. These crystals are good examples that prove that physical and chemical properties of nano/microstructured materials are related to their structures, and the precise control of the morphology of such functional materials could allow for the control of their performance.     

溶剂极性控制下的煤抽余物吸附甲烷能力研究

基于原煤和有机溶剂抽余物的等温吸附实验结果,对比分析溶剂极性与其煤抽余物吸附甲烷能力变化关系,探讨抽提溶剂极性差异对煤抽余物吸附甲烷能力控制的地球化学机理。结果表明,煤溶剂抽余物等温吸附甲烷曲线都遵循Langmuir方程,且二硫化碳(CS₂)和苯(C₆H₆)溶剂抽提作用增大了煤吸附甲烷量,四氢呋喃(THF)和丙酮溶剂抽提作用减小了煤吸附甲烷量。实验发现,煤抽余物吸附甲烷能力变化与抽提溶剂极性成负相关关系,该现象可用相似相容原理解释:CS₂和C₆H₆溶剂极性较弱,抽提出较多具有非极性结构(-CH₃和-CH₂-)的烷烃和芳烃,为甲烷在煤表面吸附增多了吸附位而增强了抽余物吸附甲烷能力,THF和丙酮溶剂极性较强,抽提出较多具有极性结构(-CHO、-OH、和-COOH)的非烃和沥青质,减少了吸附位而降低煤抽余物的甲烷吸附能力。     

Topological Effect on the Structure of Self‐Assembled Aggregates from Amphiphilic Macromolecules in Solution

The self‐assembled morphologies of cyclic amphiphiles, which are composed of a long hydrophobic block and a short hydrophilic block, in selective solutions are studied by using a simulated annealing method. The morphological dependence of the aggregates on solvent quality is investigated. The topology effects are studied by comparing results from linear counterparts of the amphiphiles. It is observed that, in addition to spherical micelles, cylindrical micelles, disklike micelles, vesicles, and large compound micelles, muticompartment vesicles with several fluidic cores can be formed by the cyclic systems. The morphologies are regulated by the interaction parameter ε_AS between the hydrophobic block and solvents. Furthermore, it is revealed that the differences of characteristics of the self‐assembled aggregates originate from the difference in architectural constraint. The wide region of forming multicompartment vesicles suggests that cyclic amphiphilic macromolecules could be a suitable candidate for applications to deliver multiple functional components by compartmentalizing different components in different confined space of vesicles.     

Hydrothermal Synthesis of Nickel Phosphate Nanorods for High‐Performance Flexible Asymmetric All‐Solid‐State Supercapacitors

Ni₂₀[(OH)₁₂(H₂O)₆][(HPO₄)₈(PO₄)₄]·12H₂O nanorods are successfully synthesized via a one‐pot hydrothermal reaction. A high‐performance flexible asymmetric all‐solid‐state supercapacitor based on the obtained Ni₂₀[(OH)₁₂(H₂O)₆][(HPO₄)₈(PO₄)₄]·12H₂O nanorods (positive electrode) and graphene nanosheets (negative electrode) is successfully assembled. It is the first report of this nanomaterial applied for all‐solid‐state supercapacitors. Interestingly, a maximum volumetric energy density of 0.446 mW h cm^?3 at a current density of 0.5 mA cm^?2 and a maximum power density of 44.1 mW cm^?3 at a current density of 6.0 mA cm^?2 are achieved by the as‐assembled device. What's more, the device also shows excellent mechanical flexibility and little capacitance change after over 5000 charge/discharge cycles at a current density of 0.5 mA cm^?2.     

High speed injection molding of high density polyethylene �� Effects of injection speed on structure and properties

Thin wall samples of high density polyethylene (HDPE) were prepared via injection molding with different injection speeds ranging from 100 mm/s to 1200 mm/s. A significant decrease in the tensile strength and Young??s modulus was observed with increasing injection speed. In order to investigate the mechanism behind this decrease, the orientation, molecular weight, molecular weight distribution, melt flow rate, crystallinity and crystal morphology of HDPE were characterized using two-dimensional wide-angle X-ray diffraction (2D-WAXD), gel permeation chromatography (GPC), capillary rheometry and differential scanning calorimetry (DSC), respectively. It is demonstrated that the orientation, molecular weight, molecular weight distribution, melt flow rate and crystallinity have no obvious change with increasing injection speed. Nevertheless, the content of extended chain crystals or large folded chain crystals was found to decrease with increasing injection speed. Therefore, it is concluded that the decrease in tensile properties is mainly contributed by the reduced content of extended chain crystals or large folded chain crystals. This study provides industry with valuable information for the application of high speed injection molding.     

Two mononuclear octahedral complexes with benzimidazole‐2‐carboxylate: supramolecular networks constructed by hydrogen bonds

The title compounds, trans‐bis(1H‐benzimidazole‐2‐carboxylato‐κ²N³,O)bis(ethanol‐κO)cadmium(II), [Cd(C₈H₅N₂O₂)₂(C₂H₆O)₂], (I), and trans‐bis(1H‐benzimidazole‐κN³)bis(1H‐benzimidazole‐2‐carboxylato‐κ²N³,O)nickel(II), [Ni(C₈H₅N₂O₂)₂(C₇H₆N₂)₂], (II), are hydrogen‐bonded supramolecular complexes. In (I), the Cd^II ion is six‐coordinated by two O atoms from two ethanol molecules, and by two O and two N atoms from two bidentate benzimidazole‐2‐carboxylate (HBIC) ligands, giving a distorted octahedral geometry. The combination of O—H...O and N—H...O hydrogen bonds results in two‐dimensional layers parallel to the ab plane. In (II), the six‐coordinated Ni^II atom, which lies on an inversion centre, shows a similar distorted octahedral geometry to the Cd^II ion in (I); two benzimidazole molecules occupy the axial sites and the equatorial plane contains two chelating HBIC ligands. Pairs of N—H...O hydrogen bonds between pairs of HBIC anions connect adjacent Ni^II coordination units to form a one‐dimensional chain parallel to the a axis. Moreover, these one‐dimensional chains are further linked via N—H...O hydrogen bonds between HBIC anions and benzimidazole molecules to generate a three‐dimensional supramolecular framework. The two compounds show quite different supramolecular networks, which may be explained by the fact that different co‐ligands occupy the axial sites in the coordination units.     

OSCILLATION OF SOLUTIONS TO SECOND ORDER NEUTRAL PARTIAL FUNCTIONAL DIFFERENTIAL EQUATIONS

Some new oscillation criteria are established for a second order neutral partial functional differential equation.Assumptions in our theorems are less restrictive,also the proofs are simpler than those in Li and Cui [11].We remove some assumptions that are required for the related results in the previous papers,thus our results generalize and improve many known conclusions.