Synthesis of PDMS-Based Porous Materials for Biomedical Applications

Polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS)-based porous organically modified silicates (ORMOSILs) for biomedical applications were synthesized through a sol-gel process, using sucrose particles as templates. These materials were characterized by ²⁹Si CP-MAS NMR spectroscopy, thin film X-ray diffraction, and scanning electron microscopy. Their bioactivity was evaluated using a simulated body fluid (SBF) of Kokubo recipe. These materials had a bimodal porous structure with pores of 300–500 m and 10–50 m in diameter. NMR showed that the silanol groups of the PDMS chain cross-linked to silica derived from the hydrolysis and condensation of TEOS. The samples containing Ca(II) exhibited apatite deposition on the pore walls within 3 days in SBF.     

Direct determination of the stereoisomer constitution by 2D-HPLC and stereochemistry-pheromone activity relationship of the copulation release pheromone of the cowpea weevil, Callosobruchus maculatus

The copulation release pheromone of the cowpea weevil, Callosobruchus maculatus, was re-isolated from about 30,000 virgin female. The natural pheromone was confirmed to be stereochemically impure by Ohrui-Akasaka-2D-HPLC methodology. The structure-activity relationship of the pheromone was also clarified.     

Kinetics of ring-opening radical polymerization of vinyloxiranes

Ring-opening radical polymerization has been followed by the flash photolysis method. As an initiator radical, the arylthiyl radical (ArS^˙) was used; the addition reaction rate constants of ArS^˙ to vinyl monomer containing epoxy-ring such as vinyloxiranes have been determined at first. The rate constant of ring opening reaction of the adduct radical changing to ArSCH₂CH ? CROCH₂^˙ were determined in the form of the relative values, which were converted to the absolute values. The ring-opening reaction rate constants were ca. 10⁶ s^?1, which indicates that the ring-opening rates are faster than usual radical propagation rates. The rate constants for vinyl monomer with 5-member ring (1,4-epoxy-1,4-dihydronaphthalene) were similarly evaluated.     

Acceleration effect of allylic hydroxy group on ring-closing enyne metathesis of terminal alkynes: scope and application to the synthesis of isofagomine

An interesting allylic substituent effect on ring-closing enyne metathesis has been found. An allylic hydroxy group on enyne substrates accelerates ring-closing enyne metathesis of terminal alkynes. The reaction proceeds smoothly without ethylene atmosphere and/or more reactive newer generation Ru-carbene catalysts, which are generally necessary to promote the reaction. This efficient reaction was applied to the synthesis of isofagomine.     

Triebel-Lizorkin space boundedness of Marcinkiewicz integrals associated to surfaces

In the present paper, we consider the boundedness of Marcinkiewicz integral operator μΩ,h,φalong a surface Γ = {x = φ(|y|)y/|y|)} on the Triebel-Lizorkin space Fαp,q(Rn) for Ωbelonging to H1(Sn-1) and some class W Fα(Sn-1), which relates to Grafakos-Stefanov class.Some previous results are extended and improved.     

Sequential perfluoroalkylation and asymmetric reduction of nitriles triggered with perfluoroalkyl titanates: catalytic asymmetric synthesis of perfluoroalkyl amines

Highly enantio-enriched perfluoroalkyl amines are shown to be synthesized by perfluoroalkylation and asymmetric reduction of nitriles. Perfluoroalkylation of nitriles can be attained by the Lewis acidic perfluoroalkyl titanate reagents to give acyclic ketimines. Catalytic asymmetric hydrogenation of the acyclic ketimines affords the perfluoroalkyl amine products in up to 93% ee.     

Miniaturized HPTLC of Vitamin B12 Compounds in Foods

High-performance thin-layer chromatography (HPTLC) is a separation technique commonly used to identify and quantify compounds in chemical mixtures. Preliminary experiments indicated that Lichrospher silica gel 60 F254s HPTLC sheets were the most suitable for analyzing vitamin B₁₂ compounds. This study revealed the advantages of miniaturized Lichrospher HPTLC for analyzing authentic vitamin B₁₂ compounds as short migration distances (5 cm) and short development times (<45 min) in combination with high separation efficiency and sensitivity (>25 pmol at 254 nm). The practicability of using miniaturized HPTLC was demonstrated by the separation and identification of vitamin B₁₂ compounds purified from foods using an immunoaffinity column.     

Singular Integral Operators on Besov Spaces

Summary. We introduce generalized BESOV spaces in terms of mean oscillation and weight functions, following a recent work of Dorronsoro, and study the continuity of singular integral operators on them. Relations between these spaces and the BESOV spaces in terms of modulus of continuity are also studied. An application to pseudo-differential operators is given.