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21.
Yasumitsu Tamura Takayuki Yakura Jun-ichi Haruta Yasuyuki Kita 《Tetrahedron letters》1985,26(32):3837-3840
A short and efficient synthesis of dihydroxyacetone groups from keto groups involving the oxidation of ethynylcarbinol intermediates with [bis(trifluoroacetoxy) iodo] benzene (PIFA), is described. 相似文献
22.
Tomihiro Nishiyama Yasumitsu Takahama Fukiko Yamada 《Journal of heterocyclic chemistry》1990,27(2):195-197
The title compounds were prepared by the reaction of the corresponding N-2-hydroxyisopropylanilines with thionyl chloride in the presence of triethylamine, and their pmr and cmr spectra were examined. On the basis of the chemical shifts due to the γ- and δ-effects, the stereochemical structures are discussed. 相似文献
23.
Yasumitsu Uraki Takeshi Imura Takao Kishimoto Mokoto Ubukata 《Cellulose (London, England)》2006,13(3):225-234
The lower critical solution temperature (LCST) of hydroxypropylcellulose bearing lignin (HPC-L) prepared from unbleached pulp depends on the amount of residual lignin. An HPC-L gel having thermal properties reflective of original HPC-L was prepared using ethyleneglycol diglycidylether as a crosslinker, as previously reported [Uraki et al. (2004) Carbohydr. Polym. 58:123–130], and the volume transition temperature was detected as an endothermic peak by differential scanning calorimetry (DSC). The adsorption and release behavior of the guest molecules to/from this gel was then examined. When the adsorption of cationic and anionic guests was compared, cationic methylene blue (MB) was adsorbed in larger amounts than anionic methyl orange (MO). In addition, MB adsorption into the HPC-L gel was greater than MB adsorption into the HPC gel prepared from commercially available HPC. This suggests that residual lignin affects the adsorption of organic dyes. Significant differences were not observed with respect to the release of MB from HPC-L at 38 °C and lower temperatures. In the adsorption of surfactants, marked adsorption at around the critical micelle concentration of the ionic surfactants and gel swelling were observed. Such swelling did not occur in the aqueous nonionic surfactant solution, although the nonionic surfactant was adsorbed into the gel. Gel swelling may have been caused by the electrostatic repulsion of the ionic surfactants adsorbed onto the polymer chains within the gel structure. 相似文献
24.
Yasumitsu Matsuo Yasuhito Tanaka Junko Hatori Seiichiro Ikehata 《Solid State Communications》2005,134(5):361-365
We have investigated the origin of the change in proton activity in the phase transition at TII-III (=369 K) in Cs3H(SeO4)2 from the viewpoint of its ferroelasticity by using 1H NMR and X-ray measurements. It is found that the second moment of the 1H NMR absorption line rapidly decreases at TII-III with increasing temperature. From this result, we conclude that the hopping motion of a proton, which is the precursor motion in the superprotonic phase, becomes more active above TII-III. This result is consistent with the fact that the electrical conductivity in phase II is larger than that in phase III. Furthermore, it is also found that the spontaneous strain decreases abruptly at TII-III. From these results, it is deduced that the decrease in the spontaneous strain at TII-III causes the increase in the proton activity at TII-III. In addition, it is deduced that the increase in proton activity and the decrease in the spontaneous strain at TII-III are closely related with the appearance of the superprotonic phase transition at TI-II (=456 K). 相似文献
25.
Yasumitsu Matsuo Go Kumasaka Keiko Saito Seiichiro Ikehata 《Solid State Communications》2005,133(1):61-64
We have fabricated a fuel cell based on the DNA film (DNAFC) and examined its properties under various humidity conditions at room temperature. The open-circuit voltage of a DNAFC is generated by supplying H2 gas to the anode. The open-circuit voltage strongly depends on the humidity conditions, and in a DNA film, the optimum condition in which the open-circuit voltage attains a value as high as 0.55 V is achieved under the relative humidity condition of 55%. Furthermore, the cell voltage of the DNAFC decreases with an increase in current density, as observed in fuel cells such as proton exchange membrane fuel cell, solid oxide fuel cell, and several others. These results indicate that DNA film can be used as the fuel cell electrolyte under approximately 55% humidity condition. 相似文献
26.
Dumont E Ogra Y Vanhaecke F Suzuki KT Cornelis R 《Analytical and bioanalytical chemistry》2006,384(5):1196-1206
Liquid chromatography (LC) hyphenated with both elemental and molecular mass spectrometry has been used for Se speciation
in Se-enriched garlic. Different species were separated by ion-pair liquid chromatography–inductively coupled plasma mass
spectrometry (LC–ICP–MS) after hot-water extraction. They were identified by on-line reversed-phase liquid chromatography–electrospray
ionization tandem mass spectrometry (RPLC–ESI–MS–MS). Se-methionine and Se-methylselenocysteine were determined by monitoring
their product ions. Another compound, γ-glutamyl-Se-methylselenocysteine, shown to be the most abundant form of Se in the
garlic, was determined without any additional sample pre-treatment after extraction and without the need for a synthesized
standard. Product ions for this dipeptide were detected by LC–ESI–MS–MS for three isotopes of Se—78
Se, 80Se: and 82Se. The method was extended to the species extracted during in-vitro gastrointestinal digestion. Because both Se-methylselenocysteine
and γ-glutamyl-Se-methylselenocysteine have anticarcinogenic properties, their extractability and stability during human digestion
are very important. Garlic was also treated with saliva, to enable detection and analysis of species extracted during mastication.
Detailed information on the extractability of selenium species by both simulated gastric and intestinal fluid are given, and
variation of the distribution of Se among the different species with time is discussed. Although the main species in garlic
is the dipeptide γ-glutamyl-Se-methylselenocysteine, Se-methylselenocysteine is the main compound present in the extracts
after treatment with gastrointestinal fluids. Two more, so far unknown compounds were observed in the chromatogram. The extracted
species and their transformations were analysed by combining LC–ICP–MS and LC–ESI–MS–MS. In both the simulated gastric and
intestinal digests, Se-methionine, Se-methylselenocysteine, and γ-glutamyl-Se-methylselenocysteine could be determined by
LC–ESI–MS–MS by measuring their typical product ions.
相似文献
27.
Ogra Y Ishiwata K Ruiz Encinar J Łobiński R Suzuki KT 《Analytical and bioanalytical chemistry》2004,379(5-6):861-866
The major selenium compound in an aqueous extract of the most popular mushroom in Eastern Asian countries, shiitake (Lentinula edodes), fortified with selenium (Se) was identified by means of hyphenated techniques, i.e. HPLC-inductively coupled argon plasma mass spectrometry and HPLC-electrospray ionization mass spectrometry (HPLC–ICP MS and HPLC–ESI MS). Sixty-eight per cent of the total Se in the selenized shiitake was extracted with water, and 49.8% of the Se in the water extract was eluted in the high molecular mass fraction (>40,000 kDa) before incubation at 37 °C. After incubation, 40.6% of the Se in the water extract was eluted in a lower molecular mass fraction and the Se eluted in the high molecular mass fraction had decreased to 14.0%, suggesting that the major selenium compound in the water extract was initially in a form bound to macromolecule(s) and was then enzymatically liberated from the macromolecule(s). The retention time of the liberated selenium compound in HPLC–ICP MS matched that of selenomethionine (SeMet), and the masses of molecular and fragment ions detected by HPLC–ESI MS also suggested that the selenium compound was SeMet. The selenized shiitake accumulated Se as SeMet, and SeMet might be bound to the water extractable high molecular mass protein(s).Electronic Supplementary Material Supplementary material is available for this article at 相似文献
28.
Yasumitsu Tamura Sundo Kwon Moon Woo Chun Masazumi Ikeda 《Journal of heterocyclic chemistry》1978,15(3):425-427
Treatment of indole, 2-phenylindole, 2-methylindole, and ethyl indole-2-carboxylate with thiocyanogen in acetic acid at 0° afforded the corresponding 3-thiocyanatoindoles in quantitative yields, whereas similar treatment of 3-methyl-2-phenylindoles and 2,3-diphenylindoles gave the corresponding 6-thiocyanatoindoles in high yields. 相似文献
29.
Yasumitsu Tamura Hironori Hayashi Joong-Heup Kim Masazumi Ikeda 《Journal of heterocyclic chemistry》1973,10(6):947-951
The reaction of 2-amino-and 2-acylaminothiazoles with O-mesitylenesulfonylhydroxylamine resulted in the ready formation in the corresponding 3-aminium salts, which were converted into thiazolo[3,2-b]-s-triazoles in high yields. 相似文献
30.