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21.
Shigeru Kiryu Yusuke Inoue Kohki Yoshikawa Morio Shimada Makoto Watanabe Kuni Ohtomo 《Magnetic resonance imaging》2010
In magnetic resonance (MR) imaging of small animals, the gastrointestinal contents may give rise to intense signals on T1-weighted images. The aim of this study was to determine the optimal dietary preparation to reduce gastrointestinal signals in mice and to evaluate the usefulness of this approach. Images of the mouse trunk were obtained using a T1-weighted, three-dimensional fast low-angle shot sequence under various dietary conditions and were compared with respect to the gastrointestinal signals and image quality. The dietary preparation studied included giving alternative diets for 24 h, intestinal cleansing, and 6-h fasting. Mice with and without dietary preparation underwent MR lymphography using gadofluorine 8, and the visualization of abdominal lymph nodes was compared. In the absence of dietary preparation, hyperintense areas were conspicuous in the gastrointestinal system, whereas on the images taken from mice fed potato or sweet potato for 24 h before imaging, gastrointestinal hyperintensity was less prominent. This preparation also reduced artifactual signals and resulted in higher-quality images of the kidneys. Intestinal cleansing, which consisted of 24-h fasting and laxative intake, did not reduce the gastrointestinal signals and caused signal changes that were indicative of fatty liver development. Some of the abdominal lymph nodes of the mice that did not receive dietary preparation were visualized on MR lymphography source images but not on maximum intensity projection (MIP) images. In contrast, on the MIP images of mice fed potato, all the lymph nodes delineated on the source images were successfully visualized. In conclusion, feeding mice potato or sweet potato for 24 h before MR imaging reduces the gastrointestinal signals and image degradation due to artifacts. Appropriate dietary preparations facilitate the display of target structures on MIP images and are expected to enhance the capabilities of small animal MR imaging. 相似文献
22.
Motokura K Nakagiri N Mori K Mizugaki T Ebitani K Jitsukawa K Kaneda K 《Organic letters》2006,8(20):4617-4620
Nucleophilic addition of sulfonamides and carboxamides to simple alkenes proceeded smoothly using a proton-exchanged montmorillonite catalyst. The spent catalyst was recovered easily from the reaction mixture and was reusable at least five times without any loss of activity. The unique acidity of the proton-exchanged montmorillonite (H-mont) catalyst was found to be applicable to additional reactions: substitution of hydroxyl groups of alcohols with amides and anilines. 相似文献
23.
Kohki Fujikawa Tomohiro Nohara Hiromune Ando Hideharu Ishida Makoto Kiso 《Tetrahedron letters》2010,51(7):1126-5815
A cyclic glucosyl ceramide (GlcCer) acceptor has been developed as a versatile building block for the synthesis of complex ganglioside. A macrocyclic GlcCer acceptor, which was the product of intramolecular glycosylation between glucose and ceramide, exhibited high reactivity during the coupling reactions with a variety of complex oligosaccharyl donors, thereby furnishing the corresponding ganglioside frameworks in high yields. 相似文献
24.
Kawabata T Mizugaki T Ebitani K Kaneda K 《Journal of the American Chemical Society》2003,125(35):10486-10487
Treatment of a Na+-exchanged montmorillonite with an aqueous Sc(OTf)3 solution afforded a robust Sc3+ aqua complex enwrapped by the silicate layers of the montmorillonites (Sc3+-mont). The resulting Sc3+-mont showed outstanding catalytic activities for the Michael reaction of 1,3-dicarbonyls under aqueous and solvent-free conditions. Moreover, this heterogeneous catalyst had an advantage of a strikingly simple workup procedure over the Lewis acids reported to date and was reusable without any appreciable losses in its activity and selectivity. 相似文献
25.
K. Ebitani Y. Hirano J. -H. Kim A. Morikawa 《Reaction Kinetics and Catalysis Letters》1993,51(2):351-355
TT-phase of niobium oxide was found to decompose CCl4 into CO2 most selectively (without formation of COCl2) at 453 K among oxides, amorphous Nb2O5, TT-phase Nb2O5, SiO2–Al2O3, Al2O3, V2O5, TiO2 and ZrO2. 相似文献
26.
Kiyotomi?KanedaEmail author Kohsuke?Mori Takayoshi?Hara Tomoo?Mizugaki Kohki?Ebitani 《Catalysis Surveys from Asia》2004,8(4):231-239
Novel heterogeneous catalysts, which were designed with atomic precision, easy to prepare, and recyclable, have been developed using a unique inorganic support hydroxyapatite, Ca10(PO4)6(OH)2. The introduction of a Ru cation into the apatite framework can generate a stable monomeric phosphate complex, which exhibits prominent catalytic performances for various oxidation reactions using molecular oxygen as a primary oxidant. Treatment of the RuHAP with an aqueous solution of AgX affords cationic Ru phosphate complexes as Lewis acid catalysts, promoting Diels–Alder and aldol reactions under mild and neutral conditions. Furthermore, two classes of heterogeneous Pd catalysts were synthesized with both stoichiometric and Ca-deficient hydroxyapatites, which show specific functions for aerobic oxidation of alcohols and carbon–carbon bond-forming reactions with extremely high turnover numbers. The catalytic systems described here are simple, efficient, and general for practical organic syntheses; thus meeting the increasing demands for environmentally-benign chemical processes. 相似文献
27.
Kohki Ebitani Masaki Kato Ken Motokura Tomoo Mizugaki Kiyotomi Kaneda 《Research on Chemical Intermediates》2006,32(3):305-315
Montmorillonite-enwrapped titanium hydroxide species (Ti4+-mont) acted as a highly efficient heterogeneous acid catalyst for the acylation of aromatic compounds with acid anhydrides
or carboxylic acids. The catalytic activity of the Ti4+-mont was higher than those of other acid catalysts such as zeolites, SO
4
2−
/ZrO2 and p-toluenesulfonic acid. For example, the reaction of anisole with dodecanoic acid in the presence of the Ti4+-mont catalyst gave 1-(4-methoxyphenyl)-1-dodecanone in 97% yield. Furthermore, the Ti4+-mont catalyst was easily separated from the reaction mixture and was recyclable. 相似文献
28.
Motokura K Nishimura D Mori K Mizugaki T Ebitani K Kaneda K 《Journal of the American Chemical Society》2004,126(18):5662-5663
Treatment of a hydrotacite, Mg6Al2(OH)16CO3, with an aqueous solution of RuCl3.nH2O afforded a monomeric Ru(IV) species on the surface of the hydrotalcite. This novel Ru-grafted hydrotalcite (Ru/HT) efficiently catalyzed alpha-alkylation of nitriles with primary alcohols through the cooperative catalysis between the Ru species and the surface base sites. The catalyst system could be further extended for the one-pot synthesis of alpha,alpha-dialkylated phenylacetonitriles via the base-catalyzed Michael reaction of alpha-alkylated phenylacetonitrile with activate olefins. 相似文献
29.
A half-V-shaped switching ferroelectric liquid crystal (FLC) is a promising candidate for fast response displays. In the half-V FLC display, a liquid crystal with a chiral nematic–chiral smectic C phase transition is used, and the smectic layer is formed by cooling from N* to SmC* with an applied d.c. field. We studied the layer structure by means of X-ray measurements for two axes (ω and χ). By using a point-focused X-ray tube and optimizing the slit width, we succeeded in the two-axis measurement with a commercial X-ray system. The ω–χ profile of the half-V FLC showed two broad peaks in an arc-shaped high-intensity area. Our interpretation of this result is that the major part of the layer consists of a tilted-bookshelf structure and that the minor part consists of a near-bookshelf structure. Since optical microscopy observations on the half-V FLC cells showed a stripe-shaped texture, we consider that the coexistence of the tilted-bookshelf and the near-bookshelf structures forms the stripe-shaped patterns. The radius of the arc-shaped high-intensity area was nearly equal to the molecular tilt angle. This result can explain why the half-V FLC showed a desirable black appearance in spite of the stripe-shaped texture. 相似文献
30.
Poly(N-vinyl-2-pyrrolidone)-capped ruthenium-supported hydroxyapatite (Ru-PVP/HAP) shows significant activity for the synthesis of furfurylamine (FAM) via the reductive amination of furfural. As-prepared 5 wt% Ru-PVP/HAP affords 50 % yield of FAM in 25 % NH3 aqueous solution under pressurized H2 gas (2.5 atm), and the highest yield approaches 60 % at 4.0 H2 atm. Comparison between the activities over four Ru-supported HAP catalysts prepared with different methods and the results of X-ray absorption spectroscopy suggested that the metallic Ru cluster is the active center for the reductive amination of furfural. Transmission electron microscope and inductively-coupled plasma analysis indicated that the as-prepared 5 wt% Ru-PVP/HAP catalyst possessed 4.0 wt% PVP-capped Ru clusters with average diameter of 1.7 ± 0.3 nm on HAP support. It was also demonstrated that the reductive amination approach with Ru-PVP/HAP catalyst, NH3 aq. and pressurized H2 gas has capability for transformation of aromatic aldehydes to the corresponding aromatic amines. According to these results, it is concluded that Ru(0) cluster supported on HAP will represent a suitable catalyst for widely-usable reductive amination to convert an aldehyde functionality towards an amine. 相似文献