纳米SnO2/TiO2电极的制备及其电催化降解间-硝基苯酚

用电化学方法在乙二醇溶液中制备锡、钛醇盐配合物Sn0.75Ti(OCH2CH2OH)(7-x),将电解液水解、干燥后在400℃煅烧2 h,得到纳米级SnO2/TiO2粉体。通过红外光谱(FT-IR)和拉曼光谱(Raman)对电解产物进行测试,纳米SnO2/TiO2粉体通过X射线粉末衍射(XRD)和扫描电子显微镜(SEM)进行表征。实验表明,在有机体系电解得到的纳米SnO2/TiO2粉体颗粒分散较理想,粒径在100～200 nm。再通过溶胶-凝胶法在钛丝表面得到纳米SnO2/TiO2电极,采用循环伏安法研究电极在酸性溶液和间-硝基苯酚溶液中的氧化还原行为和电催化活性。结果表明,纳米TiO2掺杂SnO2电极的氧化峰电流达到143×10-3A/cm2,氧化还原峰电位差明显减小,催化降解间-硝基苯酚的COD去除率达到86.1%,具有较高的电催化活性。     

稀土对中碳中合金ZG70Cr2MnNiSi钢组织和性能的影响

中碳中合金钢是近年发展起来的一种新型耐磨材料,可通过微合金化和变质处理来提高该钢种的强韧性。本研究以ZG70Cr2MnNiSi钢为研究对象,选用了两种稀土复合变质剂对其进行变质处理,测试并比较了不同变质剂处理后钢的力学性能和磨损性能,分析了钢的XRD物相图谱、金相组织、断口形貌和TEM微观组织,研究结果表明:变质处理有利于马氏体高密度位错的形成,促进了组织细化和碳化物的弥散析出,从而提高了铸钢的综合力学性能。     

Synthesis and characterization of TiO2/Fe2O3 core-shell nanocomposition film and their photoelectrochemical property

TiO₂/Fe₂O₃ core-shell nanocomposition film has been fabricated via two-step method. TiO₂ nanorod arrays are synthesized by a facile hydrothermal method, and followed by Fe₂O₃ nanoparticles deposited on TiO₂ nanorod arrays through an ordinary chemical bath deposition. The phase structures, morphologies, particle size, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and ultraviolet-visible (UV-vis) spectrophotometer. The results confirm that Fe₂O₃ nanoparticles of mean size ca. 10 nm coated on the surface of TiO2 NRs. After depositing Fe₂O₃, UV-vis absorption property is induces the shift to the visible-light range, the annealing temperature of 600 °C is the best condition for UV-vis absorption property of TiO₂/Fe₂O₃ nanocomposite film, and increasing Fe content, optical activity are enhanced one by one. The photoelectrochemical (PEC) performances of the as-prepared composite nanorods are determined by measuring the photo-generated currents under illumination of UV-vis light. The TiO₂ NRs modified by Fe₂O₃ show the photocurrent value of 1.36 mA/cm² at 0 V vs Ag/AgCl, which is higher than those of unmodified TiO₂ NRs.     

Investigation of SiO2/Si3N4 films prepared on sapphire by r.f. magnetron reactive sputtering

Sapphire is a desired material for infrared-transmitting windows and domes because of its excellent optical and mechanical properties. However, its thermal shock resistance is limited by loss of compressive strength along the c-axis of the crystal with increasing temperature. In this paper, double layer films of SiO₂/Si₃N₄ were prepared on sapphire (α-Al₂O₃) by radio frequency magnetron reactive sputtering in order to increase both transmission and high temperature mechanical performance of infrared windows of sapphire. Composition and structure of each layer of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. Surface morphology and roughness of coated and uncoated sapphire have been measured using a talysurf. Flexural strengths of sapphire sample uncoated and coated with SiO₂/Si₃N₄ have been studied by 3-point bending tests at different temperatures. The results show that SiO₂/Si₃N₄ films can improve the surface morphology and reduce the surface roughness of sapphire substrate. In addition, the designed SiO₂/Si₃N₄ films can increase the transmission of sapphire in mid-wave infrared and strengthen sapphire at high temperatures. Results for 3-point bending tests indicated that the SiO₂/Si₃N₄ films increased the flexural strength of c-axis sapphire by a factor of about 1.4 at 800 °C.     

Transverse coupling between two general biisotropic slabs

The general formulation for the determining of transverse coupling behaviour between two different biisotropic slabs is proposed based on the method of conventional field perturbation, and some special cases are considered. Since biisotropic medium is a generalization of the well-studied nonreciprocal and reciprocal chiral media, our results are suitable for much more cases.     

Anthocyanins attenuate alcohol-induced hepatic injury by inhibiting pro-inflammation signalling

We assessed phytochemical components of anthocyanins from purple sweet potato (PSP) and purple potato (PP) with UPLC-MS/MS, and investigated their inhibitory effect on inflammatory response in alcoholic liver disease (ALD). Results showed that serum AST and ALT levels in PP anthocyanins (PPAs) and PSP anthocyanins (PSPAs) treatments were lower than those of alcohol-treated group. PPAs and PSPAs could inhibit mRNA expressions of inflammatory factors (TNF-α, VCAM-1, IFN-γ and CXCL-1). The mRNA levels of NF-κB, STAT, and TLR in PPAs and PSPAs treatment groups were lower than in alcohol treatment group. Our results indicate that PP and PSP are good source of anti-inflammatory anthocyanins to prevent ALD.     

Materials doping through sol–gel chemistry: a little something can make a big difference

Several examples of sol–gel preparation of doped materials are taken to illustrate the various situations where the doping elements are responsible for the main function of the material or govern its structure. Other examples are used to illustrate that sometimes unexpected effects can be observed like structural modification and the appearance of new properties. Rare earth doped scintillators demonstrate higher homogeneity for materials prepared via sol–gel chemistry when compared with classical solid state reaction. The XRD study of rare earth doped orthoborates shows that doping can affect the vaterite to calcite phase transition observed in these compounds. A Raman spectroscopic study has been performed on doped silica xerogels and it has been shown that doping ions can modify greatly the densification process in these amorphous materials. Finally, it has been evidenced that sol–gel chemistry allows the preparation of bioactive ceramics with enhanced properties. In particular Zn-doped HAP with anti inflammatory properties has been prepared and Sr-doped bioactive glasses have demonstrated superior in-vitro bioactivity as evidenced by PIXE-RBS study.     

Proline as Lewis base catalyst: diastereoselective synthesis of isoxazoline-N-oxide through [3 + 2] cycloaddition

A catalytic cascade synthesis of isoxazoline-N-oxide was developed through proline-catalyzed nitroalkene activation. A large substrate scope was obtained with good to excellent yields. Mechanistic studies revealed intramolecular cyclization as the rate-determining step, giving only trans isomers in all cases.