TiO2光催化技术在饮用水深度处理中的研究进展

TiO2光催化技术能有效降解饮用水中微量有机污染物使之彻底矿化,并且具有很好的杀菌和抑制病毒活性的作用,是一种极具应用前景的饮用水处理技术.就光催化技术对饮用水中消毒副产物、腐殖质和内分泌干扰物的降解,微生物的灭活等诸方面的研究现状进行了系统总结与评述,并指出对其进一步研究的重要性和今后主要的研究方向.     

Adsorption and reactions of ethanol and ethanol–water mixture on alumina-supported Pt catalysts

The formation of surface species in the ethanol–water interaction and the reforming of ethanol have been investigated on Pt/Al₂O₃ catalysts and for comparison on the support. By means of infrared spectroscopy it was found that on Pt/Al₂O₃ not only adsorbed ethanol, different types of ethoxy species but also traces of acetaldehyde and a significant amount of acetate groups were detectable on the surface. The latter species were stable even at 700 K. The gas phase analysis of the ethanol-dosed surface showed at higher temperature considerable amount of ethylene in the case of Al₂O₃ and hydrogen in the case of Pt/Al₂O₃.

In the ethanol + water reaction the selectivity of H₂ and CO₂ formation at 723 K decreased in time, while that of ethylene increased. This trend was attenuated by increasing the following parameters: water concentration, metal loading and reaction temperature. It was assumed that this behavior of Pt/Al₂O₃ in the ethanol + water reaction can be attributed to the formation of surface acetate groups which hindered the reaction on the metal, although these species were located rather on the support.     

改性方式对共沉淀法制备S2O82-/Fe2O3-SiO2催化活性的影响

对共沉淀法得到的Fe2O3-SiO2混合氧化物前驱物进行水浴及微波水热改性处理,经负载S2O82-并高温焙烧处理后得S2O22-/Fe2O3-SiO2固体酸催化剂,用乙酸/丁醇酯化催化反应评估该催化剂的催化活性.通过n2吸附/脱附测试,与水浴处理方式相比,前驱物进行微波水热改性处理制得的固体酸微孔消失,中孔增多,孔径分布更加均匀,浸溃时S2O82-在前驱物表面上很快可达到吸附平衡.当(NH4)2S2O8浸渍浓度为O.75mol/L,焙烧温度500℃,焙烧时间3 h,制得的催化剂具有较高的催化活性,催化酯化反应3 h,乙酸的转化率可达97.7%.     

The importance of information localization in scene gist recognition.

People can recognize the meaning or gist of a scene from a single glance, and a few recent studies have begun to examine the sorts of information that contribute to scene gist recognition. The authors of the present study used visual masking coupled with image manipulations (randomizing phase while maintaining the Fourier amplitude spectrum; random image structure evolution [RISE]; J. Sadr & P. Sinha, 2004) to explore whether and when unlocalized Fourier amplitude information contributes to gist perception. In 4 experiments, the authors found that differences between scene categories in the Fourier amplitude spectrum are insufficient for gist recognition or gist masking. Whereas the global 1/f spatial frequency amplitude spectra of scenes plays a role in gist masking, local phase information is necessary for gist recognition and for the strongest gist masking. Moreover, the ability to recognize the gist of a target image was influenced by mask recognizability, suggesting that conceptual masking occurs even at the earliest stages of scene processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photovoltaic properties of SnCl2Pc films and SnCl2Pc/pentacene heterostructures

The optical and photovoltaic properties of dichlorotin phthalocyanine (SnCl₂Pc) films and SnCl₂Pc/pentacene (Pn) heterostructures (HS) have been studied. Weak bands at 1.35, 1.52 and 2.05 eV have been found in absorption and modulated photoreflectance spectra of SnCl₂Pc films. These bands can be caused by the formation of charge transfer states. The low concentration of recombination centers of charge carriers has been formed on a free surface of SnCl₂Pc films. This concentration essentially decreases at air evacuation before vacuum deposition of a Pn layer. Therefore, interface with an insignificant recombination rate of charge carriers is formed for SnCl₂Pc/Pn HS.     

Air-Oxidation Behavior of a Cu60Hf25Ti15 Bulk Metallic Glass at 375–520 °C

The oxidation behavior of a Cu₆₀Hf₂₅Ti₁₅ bulk metallic glass was studied over the temperature range of 375–520 °C in dry air. The oxidation kinetics of the amorphous alloy generally followed the parabolic law at all temperatures, with an oxidation rate increasing with temperature. The oxidation rates of the amorphous alloy were much higher than those of polycrystalline pure-Cu, implying that the additions of Hf and Ti accelerated the oxidation reaction. The composition of the scales formed on the amorphous alloy was strongly temperature-dependent, since they consisted mostly of Cu₄O₃ and CuO with minor amounts of HfO₂ at T ≤ 450 °C, while mostly CuO with minor amounts of HfO₂ and Cu₂TiO₃ were detected at higher temperatures. In addition, nanocrystalline Cu₅₁Hf₁₄ and Cu₃Ti₂ phases were detected on the substrate after oxidation at T ≥ 450 °C, indicating the occurrence of phase transformation.     

Kinetics of methylamine conversion on a Pd catalyst in the presence of H2

The kinetics of disproportionation of methylamine to dimethylamine and ammonia in the presence of hydrogen have been investigated over a silica-supported palladium catalyst. At a fixed partial pressure of methylamine, the reaction rate generally increases with decreasing hydrogen partial pressure, approaching a limiting or maximum value at sufficiently low pressures of hydrogen. The existence of a maximum is supported by the observation that the presence of some hydrogen appears to be necessary for the reaction to proceed at a conveniently measurable rate. At a fixed hydrogen partial pressure, the reaction rate increases with increasing methylamine partial pressure. When the methylamine partial pressure is sufficiently low or the hydrogen partial pressure is sufficiently high, the reaction order with respect to methylamine can be somewhat higher than one. At such conditions, a mechanism involving a bimolecular reaction between two partially dehydrogenated methylamine molecules on the surface appears to make a significant contribution to the overall catalytic reaction.     

直边人口直通道临界流的理论研究

在Ｈｅｎｒｙ模型的基础上，作了一系列改进并对摩擦进行了修正，得到一均匀非平衡模型。该模型比Ｈｅｎｒｙ模型计算范围广，可计算初始饱和、欠热液体及进口含汽量不为零的直边入口、直通道、Ｌ／Ｄ＞１２的临界流。     

Defect formation in epitaxial oxide dielectric layers due to substrate surface relief

Defects were characterized in epitaxial (001) CeO₂ films deposited and planarizedin situ on patterned (001) LaAlO₃ substrates by ion beam assisted deposition (IBAD). A hill and valley structure with steps running parallel to the [100] LaAlO₃ axis was produced on the surface of the substrate by photolithography and ion beam etching prior to film deposition. A conformai epitaxial CeO₂ layer of ∼ 100 nm thickness was deposited on the heated substrate by e-beam evaporation. Lattice-matching between the e-beam film and the substrate was of the type: (001) CeO₂∥(001) LaAlO₃ and [110] CeO₂∥[100] LaAlO₃. Evaporative deposition of additional film onto the conformai layer was accompanied by bombardment with a 500 eV argon/oxygen ion beam to promotein situ planarization. Extreme lattice misfit for the orientation (001) CeO₂∥(001)LaAlO₃ and [001] CeO₂∥[001] LaAlO₃ caused formation of dislocations in the e-beam CeO₂ film in the vicinity of individual ledges in the substrate surface. Coherence of the CeO₂ film was locally lost in the step regions of the hill and valley structure. The large patterned steps, which are composed of numerous adjacent ledges in the LaAlO₃ surface, caused nucleation of CeO₂ with a tilt misalignment of up to ∼5‡ about the substrate [100]. Nucleation and growth of nonepitaxial CeO₂ crystallites was observed along the step regions of the film during the IBAD portion of deposition. Defect formation in the e-beam ceria layer due to substrate surface relief indicates that “lattice engineering≓ of multilayer epitaxial structures may not be possible when nonplanar surfaces are created during device fabrication. The IBAD CeO₂ layer was more defective than the conformai layer deposited without the impinging ion beam, even in the portions of the film where epitaxy was maintained throughout both layers.     

电流变材料及其结构设计

对各种电流变材料做了较贩综述，并从结构与性能关系的角度进行了简单的分析，以鱼电流变材料的结构设计。