超音速气流固相反应合成对二甲胺基苯甲醛缩对氨基苯甲酸Schiff碱

在自制的超音速气流固相反应装置中,以对二甲胺基苯甲醛和对氨基苯甲酸为原料合成了对二甲胺基苯甲醛缩对氨基苯甲酸 Schiff 碱。特点是采用超音速气流使对二甲胺基苯甲醛和对氨基苯甲酸在反应器中摩擦活化,再通过撞击固定靶产生快速的能量转换而发生化学反应。用傅里叶变换红外光谱、核磁共振、质谱等方法对产物进行了表征,考察了循环反应次数和反应压力对产物收率的影响。实验结果表明,对二甲胺基苯甲醛缩对氨基苯甲酸 Schiff 碱适宜的反应条件为:n(对二甲胺基苯甲醛):n(对氨基苯甲酸)=1:1,反应压力0.4 SPa,循环反应次数5次。在此条件下,原料的转化率达100%,产物收率为92.45%。     

The influence of microstructure on the failure behaviour of PEEK

In this study, different molecular weight PEEK materials were used to determine the effect of spherulite size on fracture. Melt processing of the PEEK at different temperatures produced samples of different average spherulite size. A permanganic etching technique was used to reveal the spherulites. It was found that for low molecular weight 150P PEEK, the spherulite size increased with melt processing temperature; but, for the higher molecular weight 450G PEEK, the spherulite size remained approximately constant. Also, the average spherulite size was markedly lower for the material of higher molecular weight. The failure behaviour of these samples was studied using a compact tension test. It was found that the fracture toughness of PEEK varied with processing temperature. Also, the average spherulite size of a PEEK material had a profound influence on the fracture mechanism.     

An enantiomeric pair of sodium(I) organic/inorganic frameworks having novel two-dimensional inorganic comb-like separating layers

An enantiomeric pair of sodium(I) directed organic/inorganic frameworks have been obtained via the Schiff base condensation between terephthaldicarboxaldehyde and sodium salts of D- or L-phenylalanine wherein two novel two-dimensional (2D) inorganic sodium(I) separating layers composed of fully fused twelve-membered [Na₆(H₂O)₁₂] comb-like rings are constituted. To the best of our knowledge, they are the first structural examples of terephthaldicarboxaldehyde-based chiral Schiff base compounds and 2D [Na_x(H₂O)_y]_n robust inorganic frameworks.     

Synthesis and characterization of strontium 1,3,5-benzenetricarboxylate, [Sr3(1,3,5-BTC)2(H2O)4]·H2O

A three-dimensional strontium-based metal-organic framework was constructed using 1,3,5-benzenetricarboxylic acid, [Sr₃((OOC)₃C₆H₃)₂(H₂O)₄]·H₂O. This new compound was synthesized hydrothermally and is a rare example of a strontium metal-organic network. The compound network contains three distinct Sr centers, one of which is seven-coordinate and the other two are nine-coordinate geometry. The benzene rings form a herring-bone type of arrangement down the a-axis. The material is thermally stable to ca. 230 °C and transforms to an unknown material before finally decomposing to phase-pure SrCO₃ at 650 °C. The synthesis, structure, morphology and materials properties are discussed.     

我国耐火材料真空油浸技术的现状与未来

对我国耐火材料行业的真空浸渍工艺及设备现状进行了分析，介绍了国产化真空油浸装备及工艺特点。指出今后应积极倡导推广应用高温、高压，符合环保要求的真空油浸工艺及装备。     

Negative differential resistance of porous silicon

A porous silicon Al Schottky barrier diode shows differential negative resistance. The thin wires in porous silicon have much lower electron mobility than that of thick wires, due to electron surface scattering from space confinement. The energy of carriers in thick wires increases with applied bias. Some carriers can overcome the conduction-band discontinuity and flow into the thin wires. The negative differential resistance comes from the mobility difference between thick wires and thin wires in porous silicon.     

Case Study: Modeling Tidal Transport of Urban Runoff in Channels Using the Finite-Volume Method

A coupled flow and pollutant transport model based on the finite-volume method is developed and applied to predict the tidal transport of urban runoff in a southern California network of flood control channels that drain to near-shore bathing waters. Urban runoff in southern California contains elevated levels of indicator bacteria that signal the presence of fecal pollution and pose a risk to human health, and model predictions are used to understand the transport of these pollutants toward the coastline. The model is based on 1D conservation equations for fluid mass, momentum, and pollutant mass that are solved in integral form along channel reaches. A 2D formulation is solved at channel junctions. The model incorporates the monotone upwind scheme for conservation laws approach to give a high-resolution, nonoscillatory prediction of water level, velocity, and pollutant concentration. Model predictions and field measurements of water level, velocity, and a conservative urban runoff tracer are presented and compare favorably. This case study demonstrates that this finite-volume method–based scheme results in an accurate, stable, nonoscillatory and computationally manageable model. The nonoscillatory behavior is particularly beneficial in this study, since runoff enters the channels in pulses that create large gradients in pollutant concentration.