Visible-light-induced oxidative removal of nitrogen oxides in air by metal chloride-modified titanium (IV) oxide nanoparticles

Various metal chloride-modified titanium(IV) oxide (TiO₂) (MCMT) samples were prepared by loading metal chloride on commercial TiO₂ nanoparticles (Ishihara ST-01) having a large specific surface area and used for photoinduced oxidative removal of nitrogen oxides (NO _x ) in air under irradiation of visible light and/or ultraviolet (UV) light. The NO _x removal activity of MCMT samples under photoirradiation from a blue fluorescent lamp (BFL) with a UV cut filter decreased in the following order: RhCl₃/ST-01>H₂PtCl₆/ST-01>RuCl₃/ST-01>ST-01>IrCl₄/ST-01>HAuCl₄/ST-01, indicating that RhCl₃. H₂PtCl₆ and RuCl₃ fixed on TiO₂ effectively worked as photosensitizers for NO _x removal. NO _x was almost quantitatively fixed as nitrate on RhCl₃/ST-01 photoirradiated with BFL or blue light-emitting diodes. Under irradiation of both visible light and UV light from a white fluorescent lamp, RhCl₃/ST-01 exhibited a higher level of removal of NO _x and a much lower level of release of nitrogen dioxide than did bare ST-01, indicating that RhCl₃/ST-01 effectively utilized both visible light and UV light and that two types of reaction (photosensitization by fixed RhCl₃ and photocatalysis by TiO₂) occurred over RhCl₃/ST-01.     

Ion selectivity of crown ethers investigated by UV and IR spectroscopy in a cold ion trap

Electronic and vibrational spectra of benzo-15-crown-5 (B15C5) and benzo-18-crown-6 (B18C6) complexes with alkali metal ions, M(+)?B15C5 and M(+)?B18C6 (M = Li, Na, K, Rb, and Cs), are measured using UV photodissociation (UVPD) and IR-UV double resonance spectroscopy in a cold, 22-pole ion trap. We determine the structure of conformers with the aid of density functional theory calculations. In the Na(+)?B15C5 and K(+)?B18C6 complexes, the crown ethers open the most and hold the metal ions at the center of the ether ring, demonstrating an optimum matching in size between the cavity of the crown ethers and the metal ions. For smaller ions, the crown ethers deform the ether ring to decrease the distance and increase the interaction between the metal ions and oxygen atoms; the metal ions are completely surrounded by the ether ring. In the case of larger ions, the metal ions are too large to enter the crown cavity and are positioned on it, leaving one of its sides open for further solvation. Thermochemistry data calculated on the basis of the stable conformers of the complexes suggest that the ion selectivity of crown ethers is controlled primarily by the enthalpy change for the complex formation in solution, which depends strongly on the complex structure.     

N+NO reaction on Rh(111) surfaces studied with fast near-edge X-ray absorption fine structure spectroscopy: role of NO dimer as an extrinsic precursor

We studied the mechanism of the N+NO reaction on Rh(111) surfaces by means of fast near-edge X-ray absorption fine structure spectroscopy. This reaction is important as a basis of NOx reduction reactions on platinum-group metal surfaces. Atomic nitrogen layers on Rh(111) were titrated with NO at various temperatures. N2O is exclusively formed and desorbs into the gas phase below 350 K. The consumption rate of atomic nitrogen exhibits strange temperature dependence between 100 and 350 K; the reaction proceeds slower with increasing temperature. Reaction kinetics analyses and isotope-controlled experiments have revealed that the surface N atoms do not react with chemisorbed NO molecules but with NO dimers weakly bound on top of the chemisorbed layer, which play a role as an extrinsic precursor. The present results may support the possibility that NO dimers participate in various NO-related synthetic, biochemical, and surface reactions as an intermediate.     

Triethylgallium as a nonnucleophilic base to generate enolates from ketones

Triethylgallium deprotonated cyclic and acyclic ketones at 125-175 degrees C without forming carbonyl addition products, and the resulting gallium enolates underwent facile C-benzoylation and an aldol reaction. Unsymmetrical ketones were preferentially enolized at the methylene moiety, which was under kinetic control. [reaction: see text]     

Most stable metallic phase of the mixed-valence MMX-chain, Pt2(dtp)4I (dtp = C2H5CS2-), in purely d-electronic conductors based on the transition-metal complex

The electrical resistivity and X-ray oscillation photograph measurements for an MMX-chain complex, Pt2(dtp)4I (dtp = C2H5CS2-), under high pressure were performed. We observed the most stable metallic phase (TMI = 70 K, under 2.2 GPa) in the 1-D purely d-electronic conductors and pressure-induced metal-insulator transition including the structural phase transition at 3.0 GPa.     

LET dependence of the formation of oxidative damage 8-hydroxy-2′-deoxyguanosine (8-OHdG) in 2′-deoxyguanosine aqueous solution irradiated with heavy ions

To evaluate the contribution of indirect action mediated by OH radicals in biological effects of high LET radiations, we examined the production of 8-hydroxy-2′-deoxyguanosine (8-OHdG) in 2′-deoxyguanosine aqueous solution using various ion species with an LET range from 20 to 300 keV/μm. The 8-OHdG yield decreased with increasing LET. In the hypoxic irradiation condition, the yield showed constant or rather increasing tendency above about 100 keV/μm, which is consistent with an oxygen-in-the-track hypothesis to explain the diminishment of oxygen effect.     

Permeability retrieval in InP-based waveguide optical device combined with metamaterial

An InP-based Mach-Zehnder interferometer combined with a metamaterial layer consisting of a split-ring resonator array was constructed to measure the complex permeability of the metamaterial. At a wavelength of 1.5 μm, the metamaterial showed non-unity relative permeability induced by magnetic interaction with propagating light in the device. This method of measurement would be useful to determine constitutive parameters in such waveguide-based photonic devices, allowing us to design photonic integrated circuits that make use of metamaterials.     

中国古建筑结构力学研究进展

中国古代建筑是中国古代文化的宝贵遗产. 力学的多样性也反映在古建筑 结构力学研究. 西安交通大学从1982年开始, 对以西安明代箭楼、城楼和宁波宋代保国寺 等国家重点保护文物为代表的木结构建筑, 以唐代大雁塔、小雁塔等国家重点保护文物为代 表的古代高层建筑, 和以国家重点保护文物西安古城墙为代表的砖-土结构以及钟楼、鼓楼 等中国城市的代表性古建筑的结构力学特性进行了一系列研究. 得到关于古建筑结构(如斗 拱、结构非线性、榫卯节点的接触力学特性、地宫、古代夯土、古塔基础、古城墙等)力学 特性的新认识. 本文对此进行小结, 同时也介绍近年来的其它学者的一些研究.