Gold nanoparticles located at the interface of anatase/rutile TiO2 particles as active plasmonic photocatalysts for aerobic oxidation

Visible-light irradiation (λ > 450 nm) of gold nanoparticles loaded on a mixture of anatase/rutile TiO(2) particles (Degussa, P25) promotes efficient aerobic oxidation at room temperature. The photocatalytic activity critically depends on the catalyst architecture: Au particles with <5 nm diameter located at the interface of anatase/rutile TiO(2) particles behave as the active sites for reaction. This photocatalysis is promoted via plasmon activation of the Au particles by visible light followed by consecutive electron transfer in the Au/rutile/anatase contact site. The activated Au particles transfer their conduction electrons to rutile and then to adjacent anatase TiO(2). This catalyzes the oxidation of substrates by the positively charged Au particles along with reduction of O(2) by the conduction band electrons on the surface of anatase TiO(2). This plasmonic photocatalysis is successfully promoted by sunlight exposure and enables efficient and selective aerobic oxidation of alcohols at ambient temperature.     

Phenomenon of labyrinth seal with low static pressure difference and large clearance

This paper discusses the straight-through type labyrinth seal. This labyrinth seal is used for axial flow fans, which h ave an outer ring at the blade tip to seal the clearance between the ring tip and the fan shroud, in order to prevent the reverse flow or leakage. These fans are used for the cooling of automobile radiators . In these cases, the labyrinth seal is used in an extremely low static pressure difference and a large clearance . A significant decrease of the leakage rate was reported even when the labyrinth seal rotated in comparatively low speed in this unique condition according to the authors’ former report. However, this phenomen on is differ ent from past research. Further more the cause of th is phenomenon has not been determined. Therefore, the internal flow was depicted with Computational Fluid Dynamics (CFD) in or der to clarify the ca use of this phenomenon. The results of CFD show that the leakage rate decreases significantly because the carry -over flow is intercepted in the expansion groove. This is the newly discovered phenomenon which occurs under the unique condition of an extremely low differential pressure. It has not been pointed out before as the reason why the rotation decreases the leakage rate.     

Morphological studies of a hydrogen-bonded LC polymer obtained by photopolymerization in LC solvents

Anisotropic morphologies and the phase behaviour of a hydrogen-bonded LC polymer obtained by photopolymerization in two kinds of LC solvent are discussed. The hydrogen-bonded LC monomer, 4-(6-acryloyloxyhexyloxy) benzoic acid (A6OBA), was photopolymerized in 4-cyano-4′-hexyloxybiphenyl (6OCB) and in 4-cyano-4′-undecyloxybiphenyl (11OCB), which show a nematic phase and a smectic A phase, respectively. After photo-polymerization, the LC media were removed by extraction and the pure polymer was observed by scanning electron microscopy. SEM images showed that the polymer possessed fibrous morphology with a fibre diameter of a few micrometers, based on polymerization-induced phase separation. The overall geometries reflected typical LC characteristics such as schlieren and focal-conic fan textures. It was found that the hydrogen bond between benzoic acid groups in the monomer was rigid enough to fix the anisotropic phase-separated structure forming during the early stage of phase separation; however, it could not permanently maintain the fibre structure due to dissociation at elevated temperature. X-ray measurements revealed that a well developed layer structure of the hydrogen-bonded mesogen existed in the polymer obtained from the smectic phase of 11OCB, whereas a polymer layer structure could develop only partially from the nematic phase of 6OCB.     

Study of reduction processes over cerium oxide surfaces with atomic hydrogen using ultra accelerated quantum chemical molecular dynamics

Ceria plays an important role in catalysis, due to its ability to store and release oxygen depending on the condition present in the catalyst environment. To analyze the role of ceria in catalytic reactions, it is necessary to know the details of the interaction of ceria surface with environmentally sensitive molecules. This study was conducted using ultra accelerated quantum chemical molecular dynamics. Its purpose was to investigate the reduction process of the (1 1 1) and (1 1 0) surfaces of ceria with atomic hydrogen as well as water desorption mechanisms from the surfaces. This simulation demonstrated that when a high-energy colliding hydrogen atoms are adsorbed on the ceria, it pulls up an O atom from the ceria surfaces and results in the formation of a H₂O molecule. This is the first dynamics simulation related to such reduction processes based on quantum chemistry.     

C-S bond cleavage of pyridine-2-thiol: a new functionality of quadruply bridged dinuclear platinum and palladium complexes

Treatment of pyridine-2-thiol (pytH) with H(2) (60 atm) in the presence of 5-methylpyridine-2-thiolate (5-mpyt)-bridged dinuclear Pt(III), Pt(II), or Pd(II) complexes (1 mol %) in DMF at 150 degrees C for 72 h leads to the formation of pyridine in 3-51% yield. From the (1)H NMR study of the exchange reactions and of the products under D(2) pressure, it is suggested that the catalytic reaction involves bimetallic activation of the pyt ligand followed by the liberation of pyridine and H(2)S.     

Ruthenium(II)-catalyzed [2 + 2 + 2] cycloaddition of 1,6-diynes with tricarbonyl compounds

In the presence of catalytic amounts of Cp*Ru(cod)Cl, unsymmetrical 1,6-diynes possessing a variety of functional groups reacted with electron-deficient tricarbonyl compounds at the ketone C=O double bonds to selectively afford dienones via electrocyclic ring opening of the expected alpha-pyrans. The intramolecular Michael addition of the cycloadducts having an acetyl and an alkylidenemalonate moiety gave bicyclo[3.3.0]octenone derivatives.     

Isotope-dependent crystalline phases at ambient temperature: Spectroscopic and calorimetric evidence for a deuteration-induced phase transition at 320 K in α-DCrO2

The heat capacities of HCrO₂ and DCrO₂ have been measured at temperatures between 5 and 360 K. A lambda anomaly occurred at 320 K for DCrO₂ but not for HCrO₂. Infrared spectra were recorded at temperatures between 5 and 405 K. The spectrum of DCrO₂ changed at 320 K with respect to the peak wave-number and splitting of some of the vibrations, while those of HCrO₂ depended smoothly on temperature. These experimental results are discussed in terms of a deuteration-induced phase transition.     

Evidence for muon neutrino oscillation in an accelerator-based experiment

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).     

Single-particle light scattering study of polyethyleneglycol-grafted poly(ureaurethane) microcapsule in ethanol

Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol.