Photocatalytic Reduction of Nitrate in Water on Meso-Porous Hollandite Catalyst: A New Pathway on Removal of Nitrate in Water

Photocatalysis of a hollandite compound K _x Ga _x Sn_8–x O₁₆ (x = ca. 1.8) was examined for the reduction of nitrate to N₂ with a reducing agent of methanol in water under UV irradiation. Hollandites have a characteristic one-dimensional tunnel structure. The meso-porous hollandite was prepared by sol-gel method. This hollandite was used as the photocatalyst and its reaction process was quantitatively analyzed by using ion chromatograph and on-line mass spectrometry. The hollandite photocatalyst showed a significant activity for the formation of N₂ from NO ₃ ^– . Two factors, an increase in UV intensity and a lowering in pH of the solution, contributed to improvement in the selectivity for N₂. The selectivity for N₂ was improved to reach the perfect level by adjusting the factors. Although, in the previous report, the nitrate was mainly reduced to NH ₄ ⁺ or NO ₂ ^– , the present photocatalytic conditions converted it to N₂. The observed photocatalytic reduction of NO ₃ ^– to N₂ with reducing agent CH₃OH was conjugated to the partial oxidation of CH₃OH to HCOOH. This high selective photocatalytic decomposition of NO ₃ ^– to N₂ may be a new pathway among the others reported so far, and it would be useful for environmental protection of water.     

Pareto law of the expenditure of a person in convenience stores

We study the statistical laws of the expenditure of a person in convenience stores by analyzing around 100 million receipts. The density function of expenditure exhibits a fat tail that follows a power law. Using the Lorenz curve, the Gini coefficient is estimated to be 0.70; this implies that loyal customers contribute significantly to a store’s sales. We observe the Pareto principle where both the top 25% and 2% of the customers account for 80% and 25% of the store’s sales, respectively.     

BF3·OEt2 Enhanced Yb(OTf)3-Promoted Glycosidation of 1-O-Acyl-D-Glucopyranose 1

Much attention has been paid to the synthesis of glycosides and oligosaccharides for the preparation of natural products and their analogues to investigate biological functions.² Most known glycosidation methods are based on the activation of a leaving group at the anorneric center of a glycosyl donor.³ In some cases alcohol derivatives such as ROSnBu3 and ROSiMe3 are used to increase the reactivity of glycosyl acceptors.³

     

Effect of Bi surfactant on the heteroepitaxial growth in Fe/Cr(100) multilayers

This study was to investigate the surfactant effect of Bi on the heteroepitaxial growth of Fe/Cr(100) multilayers by reflection high-energy electron diffraction (RHEED) measurements. With predeposition of submonolayer Bi on Fe(100) prior to evaporation of Fe/Cr multilayer, more long-lasting RHEED intensity oscillations were observed. This implies that the layer-by-layer growth of Fe/Cr multilayer is enhanced. The observations of grazing incidence X-ray reflectivity confirmed that the interface structures of Fe/Cr multilayer with Bi were sharper than that of multilayer without Bi. The study was also to investigate the magnetotransport properties between Bi surfactant-mediated multilayers and normal ones. The magnetoresistance (MR) ratio of the multilayers was enhanced by predeposition of Bi.     

Chromatic Properties of Si02-BaO-TiO2-K2O Series Radial Gradient-Index Material

Chromatic properties of SiO₂-BaO-TiO₂-K₂O series radial gradient-index material in the range of visible wavelengths are presented and the possibility of apochromatic microscope objectives is considered.     

Acrylic polymer/silica organic–inorganic hybrid emulsions for coating materials: Role of the silane coupling agent

Acrylic polymer/silica organic–inorganic hybrid emulsions were synthesized by a simple method, that is, a conventional emulsion polymerization and subsequent sol–gel process, to provide water‐based coating materials. The acrylic polymer emulsions contained a silane coupling agent monomer, such as methacryloxypropyltriethoxysilane, to form highly solvent‐resistant hybrid films. On the other hand, the hybrid films from the surface‐modified polymer emulsions, in which the silane coupling agent was located only on the surface of the polymer particles and the particle core was not crosslinked, did not exhibit high solvent resistance. A honeycomblike array structure, which was derived from the polymer particles (diameter ≈ 50 nm) and the silica domain, on the hybrid film surfaces was observed by atomic force microscopy. The crosslinked core part and silane coupling agent containing the shell part of the polymer particles played important roles in attaining high solvent resistance. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4736–4742, 2006     

A $$\mathbb{Z}_{2}$$-orbifold model of the symplectic fermionic vertex operator superalgebra

We give an example of an irrational C ₂-cofinite vertex operator algebra whose central charge is −2d for any positive integer d. This vertex operator algebra is given as the even part of the vertex operator superalgebra generated by d pairs of symplectic fermions, and it is just the realization of the c = −2-triplet algebra given by Kausch in the case d = 1. We also classify irreducible modules for this vertex operator algebra and determine its automorphism group. This research is supported in part by a grant from Japan Society for the Promotion of Science.