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31.
Usui S 《Journal of colloid and interface science》2008,320(1):353-359
The force of double-layer interaction between dissimilar flat oxide surfaces charged oppositely at infinite separation and with Stern-Grahame layers was calculated as a function of the surface separation under the conditions of charge regulation. The interaction force showed a monotonic attraction with respect to the surface separation, lying between constant surface potential and constant surface charge conditions. The variations of surface potentials and surface charge densities of respective double layers were also presented as functions of the surface separation. When the negative diffuse-layer potential at infinite separation changed its sign to positive as a result of specific adsorption of cations on the negatively changed surface, the double-layer interaction force showed a repulsive force barrier followed by an attraction at some particular separation. 相似文献
32.
Aratake S Itoh T Okano T Usui T Shoji M Hayashi Y 《Chemical communications (Cambridge, England)》2007,(24):2524-2526
A small organic molecule, Pro-NH(2), catalyzing the enantioselective aldol reaction "in water" not merely "in the presence of water" with good enantioselectivity has been discovered for the first time. 相似文献
33.
Allylic alcohols are chemoselectively oxidized to alpha,beta-unsaturated carbonyl compounds in high yield with aqueous H(2)O(2) in the presence of Pt black catalyst under organic solvent-free conditions. The catalyst is easily recyclable and effective for at least 7 cycles. 相似文献
34.
Usui S Fujieda H Suzuki T Yoshida N Nakagawa H Ogura M Makishima M Miyata N 《Chemical & pharmaceutical bulletin》2007,55(7):1053-1059
To find novel PPAR ligands, we prepared several 3-{3 or 4-[2-(nonylpyridin-2-ylamino)ethoxy]phenyl}propanoic acid derivatives which were designed based on the structure of our previous PPARgamma ligand 1. In PPAR binding affinity assays, compound 4, which had an ethoxy group at the C-2 position of the propanoic acid of 1, showed selective binding affinity for PPARgamma. Compound 3, with an ethyl group at the C-2 position, was found to be a PPARalpha/gamma dual ligand. Compound 6, the meta isomer of 1, has been shown to be a PPARalpha ligand. The introduction of methyl (7) and ethyl (8) groups to the C-2 position of the propanoic acid of 6 further improved PPARalpha-binding potency. In cell-based transactivation assay, compounds 3 and 4 showed dual-agonist activity toward PPARalpha and PPARgamma. Compound 6 was found to be a triple agonist and compound 8 proved to be a selective PPARalpha agonist. In the human hypodermic preadipocyte differentiation test, it was demonstrated that the maximal activity of compounds 3 and 4 was higher than that of rosiglitazone. 相似文献
35.
Usui K Hiratsuka A Shiseki K Maruo Y Matsushima T Takahashi K Unuma Y Sakairi K Namatame I Ogawa Y Yokoyama K 《Electrophoresis》2006,27(18):3635-3642
We developed a polymeric 2-DE chip system. The chip consisted of an IEF region, an SDS-PAGE region, a valveless connection port, and a sample introduction port. A "junction structure" as a valveless connection port, which allowed separating and connecting the first- and second-dimensional gels, was fabricated between their regions. A "solution inlet" as a sample introduction port was fabricated to perform the liquid and sample introductions without solution leakage. Simultaneous sample monitoring was performed using the on-chip detection system. The performances of the system were demonstrated using commercially available proteins as a standard specimen and tissue-extracted proteins as the real samples. All procedures were employed without any movement of relocation part. This new 2-D separation system realized improved labor-intensive operations and a reduced experimental time. 相似文献
36.
Hitoshi Sasaki Haruo SunakawaNorihiko Sumi Kazutomi YamamotoAkira Usui 《Journal of Crystal Growth》2009,311(10):2910-2913
A freestanding m-plane GaN wafer is fabricated by using the hydride vapor-phase epitaxy (HVPE) technique on an aluminum carbide buffer layer on an m-plane sapphire substrate. X-ray pole-figure measurements show a clear m-plane orientation of the GaN surface. The full-width at half-maximum (FWHM) of GaN (1 1¯ 0 0) X-ray rocking curve (XRC) with the scattering vector along the [1 1 2¯ 0] direction is approximately 800 arcsec; this indicates good crystallinity. On the other hand, the FWHM for the case in which the scattering vector is oriented along the [0 0 0 1] direction is broad; this suggests the influence of structural defects along this direction. In fact, basal plane stacking faults (BSF) with a density of approximately 3×105 cm−1 is observed by transmission electron microscopy (TEM). The preparation of a 45-mm-diameter m-plane GaN wafer due to spontaneous separation of the GaN layer from the sapphire substrate is demonstrated. 相似文献
37.
We present a new theorem concerning a sufficient condition for a symmetric operator acting in a complex Hilbert space to be essentially self-adjoint. By applying the theorem, we prove that the Dirac–Maxwell Hamiltonian, which describes a quantum system of a Dirac particle and a radiation field minimally interacting with each other, is essentially self-adjoint. Our theorem covers the case where the Dirac particle is in the Coulomb-type potential. 相似文献
38.
Dr. Hayato Fukuda Yuko Nishiyama Shiina Nakamura Yutaro Ohno Prof. Dr. Tadashi Eguchi Prof. Dr. Yoshiharu Iwabuchi Prof. Dr. Takeo Usui Prof. Dr. Naoki Kanoh 《化学:亚洲杂志》2012,7(12):2872-2881
We have developed two syntheses of vicenistatin and its analogues. Our first‐generation strategy included the rapid and sequential assembly of the macrocyclic lactam by using an intermolecular Horner–Wadsworth–Emmons reaction between the C3–C13 fragment and the C1–C2, C14–C19 fragment, followed by an intramolecular Stille coupling reaction. The second‐generation strategy utilized a ring‐closing metathesis of a hexaene intermediate to generate the desired 20‐membered macrolactam. This second‐generation strategy made it possible to prepare synthetic analogues of vicenistatin, including the C20‐ and/or C23‐demethyl analogues. Evaluation of the cytotoxic effect of these analogues indicated the importance of the fixed conformation of aglycon for determining the biological activity of the vicenistatins. 相似文献
39.
Y Igarashi K Aoki H Nishimura I Morishita K Usui 《Chemical & pharmaceutical bulletin》2012,60(8):1088-1091
Here, we describe the first total synthesis of hydroxyl-α- and hydroxyl-β-sanshool, which involves Suzuki-Miyaura coupling (SMC). Hydroxy-α-sanshool (1) was synthesized by SMC of bromoalkyne 4 with boronate 3 followed by (Z)-selective reduction of the triple bond in the coupling product. Hydroxy-β-sanshool (2) was synthesized by regio- and (E)-selective conversion of 4 to iodoalkene 11 followed by SMC with 3. 相似文献
40.
Hiroyuki Usui Yoshifumi Watanabe Munefumi Kanao 《Journal of heterocyclic chemistry》1993,30(2):551-552
The preparation of bicyclic 1,3,5-triazine-2,4(3H)-diones 3 has been investigated. Diphenyl iminodicarboxylate ( 2 ) reacted smoothly with cyclic amidines to give bicyclic triazinediones in good yields. 相似文献