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21.
We describe two methods for the analysis of oligosaccharide chains in glycoproteins by high-performance liquid chromatography (HPLC) and high-performance capillary electrophoresis (HPCE).O-andN-glycosidically linked oligosaccharides released from glycoproteins can be identified as their borohydride-reduced forms by anion-exchange HPLC with pulsed amperometric detection.N-Glycosidically linked oligosaccharides can also be analyzed as 2-aminopyridine derivatives by HPCE in direct zone electrophoresis mode in an acidic phosphate buffer and zone electrophoresis mode as borate complexes in an alkaline buffer. We also present a convenient procedure for the analysis of the constituent monosaccharides of these oligosaccharides chains by HPLC based on reversed-phase partition mode as 1-phenyl-3-methyl-5-pyrazolone derivatives. 相似文献
22.
A porphyrin-DNA complex in which helical porphyrin assemblies were stacked as π-stacked aggregates on a DNA scaffold was found. The complex indicates the inversions of optical rotation by only the control of ionic equilibrium without any structural changes of DNA scaffold. 相似文献
23.
Tadashi Kawai Masako Komaki Tomokazu Iyoda 《Journal of molecular catalysis. A, Chemical》2002,190(1-2):45-53
Metathesis of 2-vinyl aromatic heterocycles such as furan, thiophene, pyrrole and pyridine in the presence of a molybdenum-based Schrock catalyst has been investigated from a synthetic point of view. The self-metathesis of 2-vinyl aromatic heterocycles was not successful. However, in cross-metathesis of thiophene, furan and styrene with 1-octene, the cross-metathesis product, heterodimer, was readily obtained selectively, together with only small amounts of the two corresponding self-metathesis products. The origin of the surprisingly high selectivity of heterodimer formation was elucidated through metallacyclobutane intermediate mechanism, observations of carbenes by in situ 1H NMR, and reaction products. 相似文献
24.
Yûetsu Danzaki Kunio Takada Kazuaki Wagatsuma Masaoki Oku 《Analytical and bioanalytical chemistry》1998,361(5):410-418
A practical method to estimate spectral interferences and to select optimum analytical lines in ICP-AES is suggested. Depending on the matrix composition and the amounts of the analyte, the analytical lines suffering from little interferences and the limit of determination can be determined from calculation using spectral interference coefficients. For this calculation, the spectral interference coefficients, which are defined as apparent mass of the analyte equivalent to the spectral interference from unit mass of the interferent, are obtained experimentally for 639 emission lines of 68 elements. There is a good correlation between the coefficients obtained on two spectrometers having different resolutions. 相似文献
25.
Kazuaki Wagatsuma 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(3):231-239
The relative intensities of silver emission lines from Grimm glow discharge plasmas were investigated in the wavelength range from 160 to 600 nm when using different plasma gases. It was characteristic of the plasma excitation that the spectral patterns were strongly dependent on the nature of the plasma gas employed. Intense emission lines of silver ion were observed when argonhelium mixed gases were employed as the plasma gas. Selective excitation of the ionic lines could be principally attributed to the charge transfer collisions between silver atoms and helium ions. 相似文献
26.
[reaction: see text] Triethylborane-induced hydrometalation of alkynes proceeds in an anti manner to afford the corresponding (Z)-alkenylmetal compounds stereoselectively, where dichloroindium hydride would play a key role. A variety of functional groups including hydroxy, carbonyl, and carboxy groups were tolerant under the reaction conditions. Following iodolysis and cross-coupling reaction of the (Z)-alkenylmetal species show the usefulness of this strategy. 相似文献
27.
Stabilization of the spark-discharge point on a sample surface by laser irradiation for steel analysis. 总被引:1,自引:0,他引:1
A combined technique with laser irradiation is suggested to control spark discharge for analytical use, having a unique feature that firing points of the spark discharge can be fixed by laser irradiation. Because the spark discharge easily initiates at particular surface sites, such as non-metallic inclusions, called selective discharge, the concentration of some elements sometimes deviates from their average one in spark discharge optical emission spectrometry. Therefore, stabilization of firing points on a sample surface could improve the analytical precision. 相似文献
28.
Kazuhiro Watanabe Noboru Akino Tetsuo Aoyagi Noboru Ebisawa Yukio Fujiwara Atsusi Honda Takashi Inoue Takao Itoh Mikito Kawai Minoru Kazawa Junichi Koizumi Masaaki Kuriyama Kenji Miyamoto Naoki Miyamoto Kazuhiko Mogaki Yoshihiro Ohara Tokumichi Ohga Yoshikazu Okumura Hiroshi Oohara Katsumi Ohshima Fujio Satoh Kazuhiko Shimizu Syunji Takahashi Hirotsugu Usami Katsutomi Usui Masahiro Yamamoto Takeshi Yamazaki 《Radiation Physics and Chemistry》1997,49(6):631-639
A negative-ion-based neutral beam injector (N-NBI) has been constructed for JT-60U. The N-NBI is designed to inject 500 keV, 10 MW neutral beams using two ion sources, each producing a 500 keV, 22 A D− ion beam. In the preliminary experiment using one ion source, a D− ion beam of 13.5 A has been successfully accelerated with an energy of 400 keV (5.4 MW) for 0.12 s at an operating pressure of 0.22 Pa. This is the highest D− beam current and power in the world. Co-extracted electron current was effectively suppressed to the ratio of Ie/ID− < 1. The highest energy beam of 460 keV, 2.4 A, 0.44 s has also been obtained. To realize 1 MeV class NBI system for ITER (International Thermonuclear Experimental Reactor), demonstration of ampere class negative ion beam acceleration up to 1 MeV is an important mile stone. To achieve the mile stone, a prototype accelerator and a 1 MV, 1 A test facility called MeV Test Facility (MTF) were constructed. Up to now, an H− ion beam was accelerated up to the energy of 805 keV with an acceleration drain current of 150 mA for 1 s in a five stage electrostatic multi-aperture accelerator. 相似文献
29.
A new strategy using a BINOL derivative as a chiral leaving group and Lewis acid has been developed for enantioselective alkylation of prochiral olefins. (R)-2,2'-Bis[2-(trimethylsilyl)ethoxymethyl]-1,1'-binaphthol is demonstrated to be an effective reagent for enantioselective hydroxymethylation of silyl enol ethers and trisubstituted alkenes. Electrophilic addition to prochiral olefins is accompanied by cleavage of an acetal that is dual activated by SnCl4 and the delta-effect of silicon through the S(N)2 substitution process. Enantioselective synthesis of cyclic terpenes is also described using this strategy. 相似文献
30.
Shogo Mitsuhashi Junko Kawai Tomofumi Santa Toshimasa Toyo’oka 《Analytica chimica acta》2006,562(1):36-43
Kynurenic acid (KYNA), an endogenous antagonist of ionotropic glutamate and α7 nicotinic receptors, was fluorometrically determined by column-switching high-performance liquid chromatography (HPLC) with fluorescence detection. The HPLC system consists of two octadecyl silica (ODS) columns, both of which are connected with an anion-exchange column (trapping column). Following sample injection onto the HPLC column, KYNA was separated on the first ODS column with a mobile phase of H2O/acetonitrile (95/5) containing 0.1% acetic acid. The peak fraction of KYNA was trapped on the anion-exchange column by changing the position of a six-port valve and then introduced into the second ODS column. Subsequently, KYNA was detected fluorometrically as a fluorescence complex formed with zinc ion which was pumped constantly. Instrumental limit of detection was approximately 0.16 nM, which corresponded to 8.0 fmol (per 50 μl injection, signal to noise ratio 3), and the limit of quantification was 0.53 nM (signal to noise ratio 10). Intra- and inter-day relative standard deviations were 1.1-3.9% (n = 3) and 3.0-5.3% (n = 3), respectively. The peak of KYNA in rat plasma was clearly detected by the proposed column-switching HPLC system after a facile pretreatment procedure. Intra- and inter-day relative mean errors were −1.6-1.4% (n = 3) and −2.4 to −0.4% (n = 3), respectively, with a satisfactory precision (within 5.0%). A calibration curve for the determination of KYNA showed a good linearity (r2 > 0.999) in the range of 25-200 nM. The KYNA concentrations in the plasma of male Sprague-Dawley rats (8-week-old) were 44 ± 5.5 nM (mean ± S.E., n = 5). In ketamine-treated rats, which are animal models of schizophrenia, the plasma KYNA concentrations were significantly increased compared with those in the control rats (p < 0.05). 相似文献