Photocatalytic oxidation of acetaldehyde by hybrid Pt/WO3–MOR photocatalysts under visible or sunlight irradiation

A hybrid photocatalyst was prepared from visible light-responsive Pt/WO₃ and siliceous mordenite (MOR) zeolite by simple impregnation with an aqueous solution of (NH₄)₁₀W₁₂O₄₁·5H₂O. Unmodified Pt/WO₃ had low photocatalytic activity in gas phase oxidation of acetaldehyde because of its low surface area (3–5 m²/g). In contrast, the Pt/WO₃–MOR had higher photocatalytic activity under focused sunlight and Xe lamp irradiation. Pt/WO₃–MOR with low WO₃ content (<20 wt%) adsorbed sufficient acetaldehyde, but absorption of light in the visible region was low. The optimum zeolite content enhancing the photocatalytic activity of Pt/WO₃ was estimated to be 30–50 % (w/w). Adsorption of the gaseous reactants and the efficiency of absorption of incident light are both important aspects of high photocatalytic activity.     

Gadolinium tagging for high-precision measurements of 6 nm distances in protein assemblies by EPR

Double electron-electron resonance (DEER) distance measurements of a protein complex tagged with two Gd(3+) chelates developed for rigid positioning of the metal ion are shown to deliver outstandingly accurate distance measurements in the 6 nm range. The accuracy was assessed by comparison with modeled distance distributions based on the three-dimensional molecular structures of the protein and the tag and further comparison with paramagnetic NMR data. The close agreement between the predicted and experimentally measured distances opens new possibilities for investigating the structure of biomolecular assemblies. As an example, we show that the dimer interface of rat ERp29 in solution is the same as that determined previously for human ERp29 in the single crystal.     

Physicochemical Properties of Large-Ring Cyclodextrins (CD 18 ∼CD 21

Cyclomaltooctadecaose(CD₁₈),cyclomaltononadecaose(CD₁₉),cyclomaltoeicosaose(CD₂₀) andcyclomaltoheneicosaose(CD₂₁) are cyclic oligosaccharides composed of 18, 19, 20 and 21 D-glucose units, respectively. This report describes the physicochemical properties of CD₁₈, CD₁₉, CD₂₀ and CD₂₁ in terms of aqueous solubility, surface tension, optical rotation and acid-catalyzed hydrolysis.     

Structural stability in partially substituted lithium manganese spinel oxide cathode

LiMn₂O₄ is one of the most promising cathode materials for lithium secondary battery because of natural abundance of manganese in the crust and its low toxicity to environment. Lithium ion can almost reversibly intercalate into or deintercalate from lithium manganese spinel oxide LiMn₂O₄. A part of substitution of manganese with other transition metals brings the improvement of cycle life. We focused on the local structure of the spinels and considered the effect of the local distortion on the cycle life of the spinel cathodes. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.