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991.
Dasu S de Barbaro P Bodek A Harada H Krasny MW Lang K Riordan EM Arnold R Benton D Bosted P Clogher L deChambrier G Lung A Rock SE Szalata ZM Walker RC Filippone BW Jourdan J Milner R McKeown R Potterveld D Para A Dietrich F Van Bibber K Button-Shafer J Debebe B Hicks RS Gearhart R Whitlow LW Alster J 《Physical review letters》1988,61(9):1061-1064
992.
Oka H Harada K Suzuki M Fujii K Iwaya M Ito Y Goto T Matsumoto H Ito Y 《Journal of chromatography. A》2003,989(2):249-255
Quinoline yellow (Color Index No. 47005) consists of multiple components that show a large difference in their partition coefficients (K), ranging from 0.03 to 3.3 in the solvent system tert.-butyl methyl ether (MTBE)-1-butanol-acetonitrile-aqueous 0.1 M trifluoroacetic acid (TFA). Consequently, it requires an excessively long elution time for the simultaneous separation of all components by the standard high-speed counter-current chromatography technique, which uses a constant flow-rate of the mobile phase. In order to overcome this problem, we increased the flow-rate of the mobile phase stepwise from 0.1 to 2.0 mL/min. Using this new procedure, six components (0.2-6.1 mg) were successfully isolated from 25 mg of a commercial quinoline yellow preparation in a single run using a two-phase solvent system composed of MTBE-1-butanol-acetonitrile-aqueous 0.1 M TFA (1:3:1:5, v/v). The purified components were analyzed by high-performance liquid chromatography, electrospray ionization mass spectrometry, and nuclear magnetic resonance spectroscopy. 相似文献
993.
Akira Harada Masaoki Furue Shun-Ichi Nozakura 《Journal of polymer science. Part A, Polymer chemistry》1978,16(1):189-196
Crosslinked α- and β-cyclodextrin gels (α-CD-E and β-CD-E) were used for the chromatographic resolution of racemic mandelic acid and its derivatives. β-CD-E bound L -(+)-isomers preferentially over D -(?)-isomers and resolved DL -methyl mandelate to give a D -(?)-isomer of 100% optical purity in the first fraction. Mandelic acid, ethyl mandelate, and O-methylated mandelic acid yielded resolutions of 65–83% in initial fractions. α-CD-E, on the contrary, bound D -(?)-isomers more strongly than L -(+)-isomers, resolving DL -methyl mandelate to a smaller extent than β-CD-E. Binding of DL -mandelic acid and DL -methyl mandelate on β-CD-E was studied quantitatively by the equilibrium method. β-CD-E has a similar binding capacity to starch with 1:1 stoichiometry but bound much more strongly than starch. β-CD-E has the same mode of selectivity as starch for the asymmetric binding of the mandelic acid derivatives, but α-CD-E has a reverse selectivity to β-CD-E and starch. 相似文献
994.
Germanium(IV) is preconcentrated on Sephadex G-25 from a carbonate solution (pH 12), and desorbed into 0.1 mol dm?3 nitric acid. Iron(III) and tin(IV) in eluate were removed by a small cation-exchange column. The combination of the two columns made it possible to determine germanium in rocks at mg kg?1 levels by spectrophotometry with phenylfluorone. 相似文献
995.
Silica gel and glass beads were modified by using acid chloride of metal–tetrakis(4-carboxyphenyl)porphine (M–TCPP) through a peptide bond, and an anion-exchange resin with M–TCPP by ion-exchange reaction and physical adsorption. The carriers modified with Co3+–TCPP proved to accelerate the redox reaction which is catalyzed by glutathione oxidase (GSHOx), while those modified with Mn3+–TCPP exhibited no activity. Formation of GS-SG and hydrogen peroxide was confirmed by means of mass spectroscopy and colored reaction, respectively. The silica gel modified with Co3+–TCPP exhibited the strongest activity among the tested carriers, and was expected to be useful practically as a solid catalyst for the determination of glutathione. 相似文献
996.
Diterpenoid Leaf-Gland Pigments: 11 Coleons and Royleanones from Coleus carnosus HASSK . The above mentioned plant has been investigated for its leaf-gland pigments. The following diterpenoids have been isolated (listed according to their elution from Sephadex LH-20, SiO2 and polyamide; in parentheses the yield of each product in g/kg dried leafs): royleanone ( 1 )/6,7-dehydroroyleanone ( 2 ) (0.004, as a mixture); 7α-acetyloxyroyleanone ( 3 , 0.009); a novel dimeric diterpene of hitherto unknown structure (0.03); horminone ( 4 , 0.08); 6β-hydroxyroyleanone ( 5 , 0.04, new as a natural product); 7α-acetyloxy-6β-hydroxyroyleanone ( 6 , 5.45); 6β, 7α-dihydroxyroyleanone ( 7 , 1.20); 7α-acetyloxy-6β, 20-dihydroxyroyleanone ( 8 , 0.046, a novel compound); coleon U ( 9 , 1.32); coleon V ( 10 , 13.84); carnosolone (6α, 11, 12-trihydroxy-6,20-epoxymethano-abieta-8, 11, 13-trien-7-one ( 11 ), 1.25, a novel compound). Therefore, this plant is one of the richest one in royleanones and coleons so far investigated by us (pure crystalline compounds 2,3%, estimated total amount > 3% of dry weight). Among the isolated compounds carnosolone ( 11 ) is of special interest being the first of a group of colourless diterpenoids from Coleus- and Plectranthus- species turning blue on TLC. Its oxydation product 12 is one of the rare 4-acyl-ortho-quinones having high reactivity and characteristic spectral properties. 相似文献
997.
Tada S Harada C Yoshida H Wada S Hiraya A Tanaka K Tabayashi K 《The Journal of chemical physics》2005,123(12):124309
Dissociation of free methyl-formate (MF), HC(O)OCH3, and its clusters (MF)n, (HC(O)OCH3)n, induced by core-level excitation was studied near the oxygen K edge by time-of-flight fragment-mass spectroscopy. Besides the protonated clusters, (MF)nH+ with n < or = 15, we identified the production for another series of (MF)mCH3OH2+ with m < or = 14 as well as methyl-oxonium ion, CH3OH2+, characteristic of hydrogen transfer reactions in the cationic clusters. Here; specifically labeled methyl-formate-d (MFD), DC(O)OCH3 was also used to examine the core-excited dissociation mechanisms. Deuterium-labeled experiments indicated that MFD+ with low internal energies, partially generated after the core excitation, produces CH3OD+ via a site-specific deuterium transfer from the alpha carbonyl in the molecular cation and that CH3OD2+ can be formed via the successive transfer of another deuterium from the neighbor molecule in the clusters. The deuteron (proton) transfer was also found to take place preferentially from the alpha carbonyl of the neighbor molecule for the production of deuteronated (MFD)nD+, (protonated (MF)nH+), clusters. The minimal energy requirement paths were examined for dimer (MF)2+ cation to support the present dissociation mechanisms of core-excited (MF)n clusters using ab initio molecular-orbital calculations. 相似文献
998.
Masashi Eto Koji Setoguchi Akiko Harada Eri Sugiyama Kazunobu Harano 《Tetrahedron letters》1998,39(52):6813
A series of crystalline host compounds, which have a bicyclo[2.2.1]heptene-7-one system, has been synthesized and their inclusion behavior has been investigated. The cycloadduct of phencyclone and N-naphthylmaleimide forms a 1:1 crystalline inclusion complex with 2-butanone. The crystal structure indicates the presence of weak lattice forces supported by CH···π and CH···O interactions. 相似文献
999.
Harada H 《Ultrasonics sonochemistry》1998,5(2):73-77
Sonolysis of carbon dioxide dissolved in water was performed from a standpoint of reducing this material in atmosphere. During one hour of sonication, the amount of CO2 decreased to about half at 5 degrees C under CO2-Ar atmosphere. The decreasing rate for CO2 followed the order Ar > He > H2 > N2 and it was down with increasing temperature in the range of 5-45 degrees C. The most favorable concentration for reducing CO2 was 0.03 (mole fraction of CO2 in gas phase). This concentration in gas phase means an equal mixture of CO2 and Ar in water, because CO2 is more soluble than Ar. Since carbon dioxide dissolved in water would be partly ionized, the roles of ions on the sonolysis were also examined. Gaseous reaction products were CO, H2 and a small amount of O2. Carbon monoxide and hydrogen might be obtained from CO2 and H2O by sonolysis, respectively. Both gases are fuel and react each other to C1 compounds such as methanol, and so on. Therefore, irradiation of ultrasonic waves should be an important technique for reducing CO2. 相似文献
1000.
Walker RC Filippone BW Jourdan J Milner R McKeown R Potterveld D Andivahis L Arnold R Benton D Bosted P deChambrier G Lung A Rock SE Szalata ZM Para A Dietrich F Van Bibber K Button-Shafer J Debebe B Hicks RS Dasu S de Barbaro P Bodek A Harada H Krasny MW Lang K Riordan EM Gearhart R Whitlow LW Alster J 《Physical review D: Particles and fields》1994,49(11):5671-5689