Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release

The spatial distribution of Ce³⁺ and Ce⁴⁺ in each particle of Ce₂Zr₂O_x in a three‐way conversion catalyst system was successfully imaged during an oxygen storage/release cycle by scanning X‐ray absorption fine structure (XAFS) using hard X‐ray nanobeams. For the first time, nano‐XAFS imaging visualized and identified the modes of non‐uniform oxygen diffusion from the interface of Pt catalyst and Ce₂Zr₂O_x support and the active parts in individual catalyst particles.     

Synthesis of dendritic oligothiophenes and their self-association properties by intermolecular pi-pi interactions

[structure: see text] The addition of oligothiophene into a dendritic structure causes a self-association behavior by intermolecular pi-pi interactions in a solution and in a solid state. Increasing the generation of the dendritic structure gives not only a high association constant but also sufficient field-effect hole mobility, which indicates that the charge-transporting passes are formed by the strong pi-pi interactions.     

A simplified modification of the AOAC official method for determination of total dietary fiber using newly developed enzymes

Since 1985, AOAC Method 985.29 has been globally adopted as a standard method for determination of total dietary fiber in foods. Nevertheless, an aspect of AOAC Method 985.29 that needs to be improved is the laborious process to treat 3 enzymes separately at their individual proper pH, which is quite time-consuming. Several examinations have been carried out to resolve this problem. The characteristics of newly developed thermostable alpha-amylase, neutral protease, and amyloglucosidase were evaluated based on the pH-activity profile and the property of starch hydrolysis in comparison with those of the conventional enzyme reagents. These 3 developed enzymes were found to work under the same pH condition and to accomplish sufficient digestion for the typical 3 starches: soluble starch, corn starch, and wheat starch. The experimental results revealed that the dietary fiber determination in foods could be performed without pH adjustment in the enzymatic digestion process. The modified method will be greatly helpful in determining the total dietary fiber contents in food materials with less laborious work and with an accuracy equivalent to that of AOAC Method 985.29.     

Lower critical solution temperature type of phase separation in aqueous mixture of polyelectrolytes

Phase separation behavior in aqueous mixture of different polyelectorolytes having like charges has been investigated as functions of concentration and charge density. When the charge densities of both polyelectorolytes were equally high, the compatibility between different polyelectorolytes was relatively good and the phase separation behavior was a normal upper critical solution temperature (UCST) type. With decreasing the charge density of one polyelectorolyte keeping the charge density of another polyelectrolyte unchanged, the compatibility between different polyelectorolytes became poorer. When the charge density of one polyelectorolyte was lowered below a certain value, the phase separation behavior suddenly changed from the UCST type to a lower critical solution temperature (LCST) type.     

Modulation of the absorption maximum of rhodopsin by amino acids in the C-terminus

Vision begins when light is absorbed by visual pigments. It is commonly believed that the absorption spectra of visual pigments are modulated by interactions between the retinal and amino acids within or near 4.5 angstroms of the retinal in the transmembrane (TM) segments. However, this dogma has not been rigorously tested. In this study, we show that the retinal-opsin interactions extend well beyond the retinal binding pocket. We found that, although it is positioned outside of TM segments, the C-terminus of the rhodopsin in the rockfish longspine thornyhead (Sebastolobus altivelis) modulates its lambda(max) by interacting mainly with the last TM segment. Our results illustrate how amino acids in the C-terminus are likely to interact with the retinal. We anticipate our analyses to be a starting point for viewing the spectral tuning of visual pigments as interactions between the retinal and key amino acids that are distributed throughout the entire pigment.     

Electrochemically assisted visible light photocatalysis in a heterosupramolecular system consisting of alpha-Fe2O3 and surfactant molecular assembly

The synergy of an anodic-biased alpha-Fe2O3 film and a cationic surfactant molecular assembly leads to a high visible light induced activity for 2-naphthol oxidation and high stability. An abrupt increase in the photocatalytic activity at a surfactant concentration of ca. 0.2 mmol dm(-3) results from the adsolubilization of 2-naphthol into the hydrophobic nanospace of the surfactant bilayer formed on the alpha-Fe2O3 surface. Also, the surfactant bilayer provides sustainable photocurrent during the reaction.     

Surface-coil-type resonators for in vivo temporal ESR measurements in different organs of nitroxide-treated rats

Three kinds of surface-coil-type resonators (SCRs) operating at 720 MHz were fabricated for in vivo temporal electron spin resonance (ESR) measurements. The inner diameter of the singleturn coil of the SCRs was 3, 4, or 10 mm. ResonatorQ increases and the detection limit decreases with coil diameter. The distance across which the microwave magnetic field can penetrate in the direction facing to the coil was about the same (about 2 mm) for all SCRs. In vivo kinetic studies of intravenously injected 4-hydroxy-2,2,6,6-tetramethylpiperidin-l-oxyl (TEMPOL) were performed at the liver, kidney, stomach, rectum, vein, and skin of rats with SCRs suited to the target areas. The halflife of TEMPOL was estimated from the exponential decay of the ESR signal intensity (the peak-to-peak height). Different sites in the rat showed apparent differences in the half-life of TEMPOL. This suggests that the apparent differences in the reducing ability of TEMPOL are related to the organ or tissue where measurement is taken because no excretion of TEMPOL was observed.     

Organic hybrid of chlorinated polyethylene and hindered phenol. II. Influence of the chemical structure of small molecules on viscoelastic properties

The viscoelastic properties and stabilities of those properties of organic hybrids consisting of chlorinated polyethylene (CPE) and tetrakis[methylene‐3‐(3‐5‐di‐tert‐butyl‐4‐hydroxy phenyl)propionyloxy]methane (AO‐60) and triethylene glycol bis[3‐(3‐tert‐butyl‐4‐hydroxy‐5‐methyl phenyl)propionyloxy] (AO‐70) were investigated. The CPE/AO‐70 hybrids show only one transition, whereas for the CPE/AO‐60 hybrids, one novel relaxation appears above the glass‐transition temperature of CPE. This relaxation on the higher temperature side in the mechanical spectrum for CPE/AO‐60 is associated with the appearance of the AO‐60‐rich phase. Furthermore, the stabilities of the viscoelastic properties and microstructures of the organic hybrids consisting of CPE and multifunctional hindered phenols are dominated by the strength of the intermolecular interaction between CPE and phenols and the conformations of the middle skeletal parts of hindered phenols. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1496–1503, 2000     

Enhancement of electroluminescence intensity in poly(3-alkylthiophene) with different alkyl side-chain length by doping of fluorescent dye

Electroluminescent diodes utilizing poly(3-alkylthiophene) (PAT) containing fluorescent dyes have been fabricated and their unique enhancement of emission characteristics have been studied. Remarkable enhancement of the electroluminescence efficiency has been observed for diodes with PAT doped with oxadiazole derivative (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole; PBD) and perylene derivative (N,N′ - Bis(2,5 - di - tert - butylphenyl) - 3,4,9,10 - perylenedi- carboximide; BPPC). The mechanism of emission enhancement by doping of PBD into PAT has been discussed with different alkyl side-chain lengths. © 1997 John Wiley & Sons, Ltd.     

Multiple cluster model (MCM) for surface reaction systems

Multiple cluster model (MCM) for investigating surface reactions is formulated. In this model the reaction center, where electron correlation effects often play a key role, is described by an accurate high‐level approximation, and bulk effects such as the lattice distortion energy are evaluated using a simple low‐level approximation. Therefore, the MCM can properly simulate the potential energy hypersurface of the surface reaction system with a feasible computational cost. Since there exists no fixed atom in the MCM, we can rigorously characterize the stationary point (the minimum energy point or the transition state) on the potential energy hypersurface by vibrational frequency analysis. The MCM can be applied not only to surface systems, but also to various large systems. A detailed comparison of the MCM with the integrated molecular orbital+molecular mechanics (IMOMM), the integrated molecular orbital+molecular orbital (IMOMO), and ONIOM developed by Morokuma and co‐workers is also presented. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 403–413, 1999