The photocatalytic reduction of nitrous oxide with propane on lead(II) ion-exchanged ZSM-5 catalysts

UV irradiation of the Pb²⁺/ZSM-5 catalyst prepared by an ion-exchange method in the presence of N₂O leads to the decomposition of N₂O into N₂. This reaction is found to be dramatically enhanced by the addition of propane to produce N₂ and oxygen-containing compounds such as ethanol or acetone. UV light effective for the reaction lies in wavelength regions shorter than 250 nm where the absorption band of the Pb²⁺ ion ([Xe] 4f¹⁴5d¹⁰6s² [Xe] 4f¹⁴5d¹⁰6s¹6p¹) exists, indicating that the excited state of the isolated Pb²⁺ ions plays a significant role in this decomposition of N₂O both in the absence and the presence of propane, and the role of propane is found to be a capture of oxygen atoms formed by the decomposition of N₂O.     

Photocatalytic oxidation of ethylene to CO2 and H2O on ultrafine powdered TiO2 photocatalysts: Effect of the presence of O2 and H2O and the addition of Pt

The complete photocatalytic oxidation of C₂H₄ with O₂ into CO₂ and H₂O has been achieved on ultrafine powdered TiO₂ photocatalysts and the addition of H₂O was found to enhance the reaction. The photocatalytic reaction has been studied by IR, ESR, and analysis of the reaction products. UV irradiation of the photocatalysts at 275 K led to the photocatalytic oxidation of C₂H₄ with O₂ into CO₂, CO, and H₂O. The large surface area of the photocatalyst is one of the most important factors in achieving a high efficiency in the photocatalytic oxidation of C₂H₄. The photoformed OH species as well as O ₂ ⁻ and O ₃ ⁻ anion radicals play a significant role as a key active species in the complete photocatalytic oxidation of C₂H₄ with O₂ into CO₂ and H₂O. Interestingly, small amount of Pt addition to the TiO₂ photocatalyst increased the amount of selective formation of CO₂ which was the oxidation product of C₂H₄ and O₂.     

Scanning tunneling microscopy and spectroscopy of electron-irradiated thin films of C60 molecules

We have used scanning tunneling microscopy and spectroscopy to determine the effect of electron irradiation on thin films of C₆₀ molecules. Upon the irradiation of electrons with an energy of 100 eV or 2 keV, clusters of molecules are created in the C₆₀ films as the initial products. The molecules in the clusters exhibit different electronic structures from that of pristine C₆₀ molecules; the molecule at the center of the cluster exhibits a metallic or semimetallic nature and the other molecules exhibit an additional density of states in the filled states. C₆₀ thin films are covered with clusters upon continuous electron irradiation for a longer duration, changing the electronic structure of the films. We consider that the electron-induced polymerization between C₆₀ molecules is responsible for the observed alteration of the C₆₀ thin films.     

The fracture mechanism of polylactic acid resin and the improving mechanism of its toughness by addition of acrylic modifier

The fracture mechanism of polylactic acid (PLA) resin and the improving mechanism of its toughness by addition of an acrylic modifier were examined. Plane strain compression testing of PLA clearly showed strong softening after yielding. Because the stress for craze nucleation of PLA was close to the yield stress, brittle fractures resulted. The addition of an acrylic modifier to the PLA significantly lowered the yield stress and formed many voids. The release of the strain constraint because of the formation of many voids and the decrease of yield stress resulted in the relaxation of stress concentration, and the toughness was improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Inhibition of cell growth by a fused protein of human ribonuclease 1 and human basic fibroblast growth factor

Pancreatic-type RNases are considered to have cytotoxic potentialdue to their ability to degrade RNA molecules when they enterthe cytosol. However, most of these RNases show little cytotoxicitybecause cells have no active uptake mechanism for these RNasesand because the ubiquitous cytoplasmic RNase inhibitor is consideredto play a protective role against the endocytotic leak of RNasesfrom the outside of cells. To study the cytotoxic potentialof RNase toward malignant cells targeting growth factor receptors,the C-terminus of human RNase 1 was fused to the N-terminusof human basic fibroblast growth factor (bFGF). This RNase–FGFfused protein effectively inhibited the growth of mouse melanomacell line B16/BL6 with high levels of cell surface FGF receptor.This effect appeared to result from prolongation of the overallcell cycle rather than the killing of cells or specific arrestin a particular phase of the cell cycle. Thus, human RNase 1fused to a ligand of cell surface molecules, such as the FGFreceptor, is shown to be an effective candidate for a selectivecell targeting agent with low toxic effects on normal cell types.     

Effects of the shapes and addition amounts of crosslinking reagents on the properties of poly-3-hydroxybutyrate/poly(caprolactone) blends

The effects of the shapes and addition amount of crosslinking reagents on the expression mechanisms of polymer properties of poly(3-hydroxybutyrate) (PHB) and poly(caprolactone) (PCL) blends are investigated. A static tensile test is carried out on 60%PHB/40%PCL blends by adding liquid and solid crosslinking reagents, showing that the Young's modulus of the blends decrease with increasing effective peroxide value of the crosslinking reagent. In addition, the elasticity of the blends increases only when the liquid crosslinker is added, even though T₁H analysis and scanning electron microscopy observation reveal that both crosslinking reagents improve the miscibility of the blend. Furthermore, the ¹H and ¹³C PST-MAS NMR spectra related to the molecular motions of polymer main chains in the blends increase with increasing effective peroxide value of the crosslinking reagents. However, the local molecular motions of substituents in the blends matched with the T₁C values reveal an opposite trend between the rigid PHB and flexible PCL with the addition of the solid crosslinker. The solid-state NMR spectral and relaxation time analyses suggest the possibility of the polymer chain scission as a side reaction, as well as the occurrence of intra-domain crosslinking, both of which reduce the toughness of the blends containing the solid crosslinker.