The photocatalytic performance of barium tantalates in the decomposition of H2O into H2 and O2 was investigated. Ba5Ta4O15 that was prepared under Ta rich atmosphere exhibited remarkable photocatalytic activity. Under the same reaction conditions, its activity was the highest among all of the alkali earth-tantalum mixed-oxide photocatalysts prepared.

Poly[2-(methacryloyloxy)ethyl phosphorylcholine]s (PMPCs) with one pendant cholesteryl moiety at the polymer end (PMPC-Chol-I and PMPC-Chol-II) and two pendant cholesteryl moieties at both polymer ends as terminal groups (PMPC-2Chol-I and PMPC-2Chol-II) were prepared by the radical polymerization of 2-(methacryloyloxy)ethyl phosphorylcholine initiated with 4,4Ј-azobis[(3-cholesteryl)-4-cyanopentanoate] in the presence of 2-mercaptoethanol or thiocholesterol as chain-transfer reagents, respectively. The self-organization of PMPC-Chol and PMPC-2Chol was analyzed with fluorescence and 1 H NMR measurements. The critical micelle concentrations of PMPC-Chol-I with a degree of polymerization (P n ) of 91 and of PMPC-2Chol-I with a P n value of 165 were 250 and 27 mg L Ϫ1 , respectively. The blood compatibility of PMPC-2Chol was evaluated from the Michaelis constant (K m ) for the enzymatic reaction of thrombin and a synthetic substrate, S-2238, in the presence of PMPC-2Chol. K m was 0.07, 0.05, and 0.56 for PMPC-2Chol-I with P n ϭ 165, PMPC-2Chol-II with P n ϭ 38, and PMPC (an intrinsic viscosity of 0.54 dL g Ϫ1 ) initiated with 2,2Ј-azobisisobutyronnitrile in the absence of chain transfer agent, respectively. A mixture of PMPC-2Chol-II and cholesterol as a drug model formed a lamellar type of complex with an interplanar spacing of d ϭ 35.2 Å.

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This paper was read a t the Annual Meeting of the Society of Fiber Science and Technology, Japan, held on 27th May, 1968. 252Crystallization of A-B-A Type Block Copolymers pros.) in quadratischen Plattchen kristallisieren, ahnlich denen der Polyathylenoxideinkristalle. Elektronenmikroskopische Aufnahmen dieser Kristalle zeigten, daB die Poly-arnethylstyrol-Ketten aus dem kristallinen Teil ausgeschlossen und wahrend der Kristallisation auf der Oberflache der Einkristalle abgeschieden werden. So bilden sich laoge Sehlaufen, die in der Losung oder beim Trocknen der Kristalle aggregieren, je nach den angewandten Losungsrnitteln. Wenn man die Konzentration des Polymeren auf 0,5 yo erhoht, bilden sich unregelmaBig geformte, mehrschichtige Kristalle, an deren Oberflache eine Anzahl von Lochern gefunden wird, was zur Annahrne fiihrt, daB die Haufigkeit des Vorkommens von Molekiilen, die mehrere Schichten miteinander vernetzen, rasch mit ansteigender Konzentration steigt.Es werden experimentelle Unterlagen fur die Bildung von langen Schlaufen auf der Oberflache der lamellaren Kristalle und von molekularen Verbindungen zwischen den einzelnen Lamellen bei der Kettenfaltungskristallisation geliefert.

The title compound, prepared under Ta-rich atmosphere, exhibits a high photocatalytic activity in the decomposition of H2O into H2 and O2. Under the same reaction conditions, its activity is the highest among all of the alkaline earth-tantalum mixed-oxide photocatalysts prepared. Its activity can be significantly improved by controlling the preparation conditions. -(OTSUKA, H.; KIM, K.; KOUZU, A.; TAKIMOTO, I.; FUJIMORI, H.; SAKATA, Y.; IMAMURA, H.; MATSUMOTO, T.; TODA, K.; Chem. Lett. 34 (2005) 6, 822-823; Dep. Adv. Mater. Sci. Eng., Fac. Eng., Yamaguchi Univ., Tokiwadai, Ube, Yamaguchi 755, Japan; Eng.) -W. Pewestorf 40-020