Planar lipid bilayer reconstitution with a micro-fluidic system

A planar lipid bilayer which is widely used for the electrophysiological study of membrane proteins in laboratories is reconstituted using a micro-fluidic system, in a manner that is suitable for automated processing. We fabricated micro-channels on both sides of the substrate, which are connected through a 100-200 microm aperture, and showed that the bilayer can be formed at the aperture by flowing the lipid solution and buffer, alternately. Parylene coating is found to be suitable for both bilayer formation and electric noise reduction. Future applications include a high-sensitivity ion sensor chip and a high-throughput drug screening device.     

Selective extraction of higher fullerenes using cyclic dimers of zinc porphyrins

Higher fullerenes (>/=C76) were selectively extracted from a fullerene mixture obtained from a combustion-based industrial production source by cyclic dimers of beta-unsubstituted porphyrin zinc complexes 2C5-2C7 with C5-C7 alkylene spacers as host molecules. Results of single extraction of the fullerene mixture with 2C5-2C7 together with a beta-substituted analogue of 2C6 (1C6) and spectroscopic titration of 2C6 and 1C6 with C60, C70, and C96 indicated that the host selectivity toward higher fullerenes is much dependent on the structure of the porphyrin units and the size of the host cavity. Sequential three-stage extraction of the fullerene mixture with the best-behaved 2C6 resulted in considerable enrichment in very rare fullerenes C102-C110 (<0.1 abs %) up to 82 abs % (C76-C114, 99 abs %) (356 nm) of total fullerenes.     

Molecular-length and chiral discriminations by beta-structural poly(L-alanine) on silica

Poly(L-alanine)-grafted porous silica (Sil-Ala22) was prepared by polymerization of N-carboxyanhydride of L-alanine initiated by 3-aminopropylated silica. Its selective interaction with aromatic guest molecules was evaluated by the retention time in liquid chromatography using the column packed with Sil-Ala22. Sil-Ala22 showed a specific selective retention with discriminating molecular shapes, such as molecular length, linearity and planarity. This selectivity can be explained by a multiple pi-pi interaction with the carbonyl groups one dimensionally-aligned on the rigid beta-form structure in the peptide main chain. Chiral separation with Sil-Ala22 was also described.     

Bivariant Chern classes for morphisms with nonsingular target varieties

W. Fulton and R. MacPherson posed the problem of unique existence of a bivariant Chern class—a Grothendieck transformation from the bivariant theory F of constructible functions to the bivariant homology theory H. J.-P. Brasselet proved the existence of a bivariant Chern class in the category of embeddable analytic varieties with cellular morphisms. In general however, the problem of uniqueness is still unresolved. In this paper we show that for morphisms having nonsingular target varieties there exists another bivariant theory of constructible functions and a unique bivariant Chern class γ: . Partially supported by Grant-in-Aid for Scientific Research (C) (No. 15540086+No. 17540088), the Japanese Ministry of Education, Science, Sports and Culture.     

Cytotoxic major saponin from tomato fruits

A major novel steroidal alkaloid glycoside, possessing cytotoxic activity has been isolated from the fruits of Lycopersicon esculentum.     

Asymmetric total synthesis of pseurotin A

The asymmetric total syntheses of pseurotin A and 8-O-demethylpseurotin A have been accomplished. Key reactions are a NaH-promoted intramolecular cyclization of an alkynylamide to form a gamma-lactam, an aldol reaction of a benzylidene-substituted ketone, and the late-stage introduction of the benzoyl group by a selective oxidation of a benzylidene moiety with dimethyldioxirane (DMD). [reaction: see text]     

On Ginzburg's bivariant Chern classes

The convolution product is an important tool in geometric representation theory. Ginzburg constructed the ``bivariant" Chern class operation from a certain convolution algebra of Lagrangian cycles to the convolution algebra of Borel-Moore homology. In this paper we prove a ``constructible function version" of one of Ginzburg's results; motivated by its proof, we introduce another bivariant algebraic homology theory on smooth morphisms of nonsingular varieties and show that the Ginzburg bivariant Chern class is the unique Grothendieck transformation from the Fulton-MacPherson bivariant theory of constructible functions to this new bivariant algebraic homology theory, modulo a reasonable conjecture. Furthermore, taking a hint from this conjecture, we introduce another bivariant theory of constructible functions, and we show that the Ginzburg bivariant Chern class is the unique Grothendieck transformation from to satisfying the ``normalization condition" and that it becomes the Chern-Schwartz-MacPherson class when restricted to the morphisms to a point.