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21.
3,4-Dhydro-6,7-dimethoxy-4-methyl-3-oxo-quinoxaline-2-carbonyl azide is a highly senstive fluorescence derivatization reagent for primary, secondary and tertiary alcohols for high-performance liquid chromatography. Reaction conditions are optimized with benzyl alcohol, n-hexanol, cyclohexanol and 2-methyl-2-butanol. The reagent reacts with the alcohols in benzene to produce the corresponding fluorescent carbamic acid esters, which can be separated on a reversed-phase column YMC Pack C8 with aqueous methanol as eluent. the detection limits for the alchols are 2–5 fmol per 10-μl njection. The reagent also reacts with hydroxysteroids with primary, secondary and/or tertiary alcoholic group(s) to form fluorescent derivatives. Hydroxycarboxylic acids and phenols do not give any chromatographic peaks. 相似文献
22.
A simple and sensitive method is described for the determination of biogenic indole compounds adsorbed on cellulose or alumina plates for thin-layer chromatography by room-temperature phosphorimetry. The optimum conditions were investigated for 5-hydroxyindole-3-acetic acid and indole-3-acetic acid. The compounds are spotted on the plates, which are then sprayed successively with sodium citrate or sodium acetate, and sodiu iodide solutions. The plates are dried completely under a stream of dry nitrogen, and immediately dipped in molten paraffin. The phosphorescence is stable for at least 3 h even in moist air. The limits of detection for nine biogenic indole compounds tested are between 2 and 300 pmol per sample spot. 相似文献
23.
Absorption and photoluminescence (PL) spectra, PL quantum efficiency, and PL lifetime have been investigated on bis(8-hydroxyquinoline)
zinc (Znq2) and magnesium (Mgq2) in solutions and powder. Znq2 and Mgq2 have the lowest-energy absorption band at 376 and 396 nm in acetonitrile solution, respectively, and emission band with peak
at 555 and 480 nm. The PL quantum efficiency is 0.03 and 0.45 for Znq2 and Mgq2 in the solution, respectively, while 0.45 and 0.36 in powder. Unlike the case of powders, two PL lifetimes are obtained in
solutions. The longer lifetime is attributed to molecule having interaction with its neighboring molecule, while the shorter
one to the isolated single molecule. 相似文献
24.
Ikuya Tagawa Yosuke UrakamiMaki Maeda Youji MaruyamaKazue Kudo Hiromi ShiinaMasafumi Mochizuki 《Journal of magnetism and magnetic materials》2012,324(3):327-329
To make the write-field much stronger with sharper cross-track field gradient in Shingled perpendicular Magnetic Recording (SMR), we have successfully developed asymmetric SMR heads with one-side shield design. Using these heads, higher track density capability on the shielded-side was demonstrated, which came from narrower erase-band width at shielded side. 相似文献
25.
26.
Tohru TakeiTakumi Ohki Yosuke HaradaNaoto Kumagai Hiroki FukumotoTake-aki Koizumi Akihiro MaedaTakahiro Kojima Yoshihisa SeiKohei Shiramizu Masahiro AbeMasashi Oota Takakazu Yamamoto 《Tetrahedron letters》2012,53(44):5907-5910
Dibromopyridines or dibromopyridone with -(CH2)m-SO3Na group(s) has been prepared via the reactions of the corresponding dibromopyridines with -OH and -NH2 groups with sultone. These compounds were converted into polymers with the -(CH2)m-SO3H groups via organometallic polycondensation. The polymer showed proton conducting properties and high stability toward oxidation. 相似文献
27.
Masami Kuriyama Satoko Tanigawa Yuki Kubo Yosuke Demizu Osamu Onomura 《Tetrahedron: Asymmetry》2010,21(11-12):1370-1373
A facile synthetic method toward optically active 3,3-disubstituted oxindoles with excellent enantioselectivity was achieved using chiral copper-catalyzed desymmetrization of prochiral 1,3-diols. The monotosylated product was transformed into oxindole derivatives efficiently. 相似文献
28.
Makoto Uchimura Ryohei Ishige Masayuki Shigeta Yuki Arakawa Yosuke Niko Junji Watanabe Gen-Ichi Konishi 《Research on Chemical Intermediates》2013,39(1):403-414
We synthesized thermotropic liquid-crystalline polyesters in which 9,10-diphenylanthracene moieties are incorporated into the main chain type of polyester forming the chiral smectic C (Sm C*). The polymers were prepared by the isopropyltitanate-catalyzed reaction of biphenyldicarboxylic acid and the corresponding diols, with different ratios of diol of 9,10-diphenylanthracene moiety to the alkane diols (1, 5, and 10 mol %) under nitrogen atmosphere. The polymers exhibited thermotropic liquid crystals despite the presence of a bulky diphenylanthracene moiety in the main chain. The circular dichroism spectra revealed that a Sm C* phase was formed in the polymer with 1 mol % of anthracene moiety, although only an Sm A phase was formed in the other polymers. This is the first example of a Sm C* polyester containing a diphenylanthracene moiety in the main chain. Furthermore, we measured the optical properties of the polymers and found that they exhibited very high fluorescent efficiency. The fluorescence spectra of the thin film differed from that of a CH2Cl2 solution. 相似文献
29.
To achieve immune homeostasis in such a harsh environment as the intestinal mucosa, both active and quiescent immunity operate simultaneously. Disruption of gut immune homeostasis leads to the development of intestinal immune diseases such as colitis and food allergies. Among various intestinal innate immune cells, mast cells (MCs) play critical roles in protective immunity against pathogenic microorganisms, especially at mucosal sites. This suggests the potential for a novel MC-targeting type of vaccine adjuvant. Dysregulated activation of MCs also results in inflammatory responses in mucosal compartments. The regulation of this yin and yang function of MCs remains to be elucidated. In this review, we focus on the roles of mucosal MCs in the regulation of intestinal allergic reaction, inflammation and their potential as a new target for the development of mucosal adjuvants. 相似文献
30.
Huihui Li Yosuke Imai Takanori Takiue Hiroki Matsubara Makoto Aratono 《Colloid and polymer science》2014,292(5):1209-1215
The composition of the adsorbed film and the excess Gibbs energy of adsorption $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were evaluated from thermodynamic analysis of surface tensions for the 1-decyl-3-methylimidazoulium bromide (C10mimBr)–tetraethylene glycol monooctyl ether (C8E4) and 1-decyl-3-methyl-imidazolium tetrafluorobrorate (C10mimBF4)–C8E4 systems, where the counter anion of imidazolium salts is different from each other. The higher miscibility of two components compared to an ideal mixing and thus negative $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were observed in the former, which comes from the ion–dipole interaction between imidazolium cation and the oxyethylene group of C8E4. On the other hand, the lower miscibility and thus positive $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were observed for the latter. Such differences were attributed to that BF4 ? forms two hydrogen bonds and has stronger affinity with the cationic head group of C10mim+ than Br?. This results in that the ion–dipole interaction between C8E4 and C10mim+ cation is diminished in the C10mimBF4–C8E4 system. 相似文献