La-OMS-2催化剂催化甲苯氧化制苯甲醛

合成了氧化锰八面体(OMS-2)分子筛,采用离子交换法和浸渍法制备了稀土金属La改性的OMS-2分子筛(La-OMS-2)催化剂,并用于甲苯液相选择性氧化制苯甲醛,考察了催化剂用量、反应温度、反应时间、氧气流量及溶剂种类对甲苯转化率和苯甲醛选择性的影响,对La-OMS-2催化剂进行了X射线衍射表征和BET比表面积测定。实验结果表明,离子交换法制备的La-OMS-2-A催化剂的活性高于浸渍法制备的La-OMS-2-B催化剂,在甲苯0.1mol、溶剂冰乙酸10mL、氧气流量60mL/min、La-OMS-2-A催化剂用量0.10g、反应温度353K、反应时间1.0h的条件下,甲苯转化率达61%,苯甲醛收率为56%。加入La对OMS-2分子筛中的MnO晶格结构产生了影响,提高了苯甲醛的收率。     

Electromagnetic properties of ferroelectric-ferrite ceramic composites

The NiFe₂O₄ and Pb(Zr_0.52Ti_0.48)O₃ ceramic composites are prepared by conventional solid state reaction method. The microstructural and morphological properties of the composites are studied by X-ray diffraction analysis and scanning electron microscopy. Results indicate that the ferrite and piezoelectric phases can co-exist in the composites. The relationship between the dielectric constant and frequency (40 Hz–40 MHz) as well as temperature is also investigated. It is noted that the transition temperature of the composites is about 380 °C. A double electric hysteresis loop is observed in our composites. The magnetic properties are relatively weak according to the magnetic hysteresis loop. With increase in the content of the ferrite phase, the permeability increases. The electromagnetic properties of the as-prepared composites are tunable according to the content of the NiFe₂O₄ phase.     

A novel poly(p-phenylene vinylene)-b-poly(methyl methacrylate) rod-coil diblock copolymer

In this letter, a novel well-defined PPV-b-PMMA rod-coil diblock copolymer, consisting of PPV oligomer as its rod block and PMMA as its coil block, respectively, was prepared via ATRP for the first time. The structure of the copolymer was determined by the measurements of FTIR, ¹H NMR and gel permeation chromatography (GPC). The thermal and optical properties of the copolymers are investigated by DSC, TGA, UV-Vis and photoluminescence (PL) spectra. The results showed that, the introduction of PMMA coil block can improve both the thermal stability and optical properties of PPV oligomer. The highly ordered hexagonally honeycomb-structured film of the copolymer fabricated by vaporizing solvent is also investigated by optical microscope and SEM.     

天然气管道燃压机组的性能试验及见证

结合西气东输管道工程燃气轮机驱动压缩机组设备订货及验收中对性能试验项目的确定、工厂试验及见证过程,介绍了燃压机组性能试验项目所涉及的主要内容、执行标准、需要达到的技术指标,各种性能试验的基本情况,买方参加工厂试验见证中需要重点处理好的问题等。以期为我国其他大型长输天然气管道机组订货及试验见证工作提供借鉴。     

Studies of substrate specificities of lipases from different sources

Although lipases are widely applied in a wide variety of reactions, available information on the factors that are responsible for the substrate specificities of lipases from different sources is scarce. In this paper, nine lipase‐producing microorganism strains were isolated from oil‐containing samples. The properties of these enzymes, including pH optima, temperature optima, thermal stability, and pH stability, vary significantly with the different sources from which these lipases were isolated. The substrate specificities of the nine lipases, including fatty acid and positional specificities, were also studied. The fatty acid specificities of the nine lipases were observably different toward 15 substrates with different carbon chain lengths, different saturation degrees and different side chains. The lipases from S₃ Penicillium citrinum (PCL), MJ₁ Aspergillus niger (ANL), MJ₂ Aspergillus oryzae (AOL), YM Bacillus coughing (BCL), S₉ Geotrichum candidum (GCL), and S₁₁ Candida lypolytica (CLL) showed the strongest specificities to short‐chain esters, and the other lipases showed strong selectivity for medium‐ or long‐chain and branched esters. The positional specificities were examined by analyzing the hydrolytic products of triolein catalyzed by the nine lipases, using TLC. The lipases can be mainly classified into two groups by their specificities for the ester bond at position 2 of triglycerides; one group can selectively hydrolyze the ester bond at position 2 of the triglycerides, the other group cannot. All these nine lipases were divided into four groups by hierarchical clustering analysis on the basis of the results of fatty acid and positional specificities.     

基于LVQ网络在轴承座松动故障诊断中的应用

把汽轮机轴承座松动的相关频段上不同频率谱的谱峰能量值作为故障信号的训练样本输入到LVQ网络中去，并由LVQ网络产生训练后不同的权重向量。由于竞争层神经元的权重分布不同，则权重分布图也不同，可根据不同的权重分布图来确认和诊断汽轮机轴承座松动故障的不同程度。     

高效方坯连铸机集成优化设计研究

在对方坯连铸关键技术参数综合研究的基础上 ,以实现正确操作和提高工艺性能为目标而进行的具有世界先进水平的高效方坯连铸机集成优化设计研究已经在实际工作条件下得到验证 ,结果证明可很好地满足质量和产量之间的相互关系。     

等温脉冲自由射流压力场动态特性的实验研究

针对冶金工业过程脉冲燃烧及脉冲流技术所进行研究的基础部分,借助于计算机辅助信号分析手段,运用湍流统计理论,对等温脉冲自由射流压力场动态特性进行了系统的实验研究。实验的Re范围为19486～93936,st范围为0～0.057,所对应的射流脉冲频率为0～25Hz。研究结果表明;脉冲射流极大地提高了射流区压力波动水平,任何受气体的动量、热量和质量传递制约的工业过程均可望通过适当地采用脉冲流技术加以强化.     

不同品种甜菜类型甜菜光合特性的研究

水文研究了甜菜生育期中不同品种类型甜菜的光合特性，结果表明在生育前期，高糖型品种的叶绿素含量高，而生育中前期以丰产型高，标准型介于二者之间，ＲｕＢＰ竣化酶活性的动态变化亦显这种趋势；在叶丛形成期和块根增长期，丰产型品种光合速度最高，在糖分积累期则以高糖型品种光合速度高；不同品种不同叶位的叶绿素含量与光合速率中呈正相关。