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11.
A Yamamoto A Matsunaga E Mizukami K Hayakawa M Miyazaki 《Journal of chromatography. A》1991,585(2):315-317
An ion chromatographic separation with photometric detection using a chiral copper(II) complex as the eluent has been developed for the resolution of enantiomers of malic acid in commercially available apple juices. The results obtained by this method were in good agreement with those by an enzymatic method with separation by high-performance liquid chromatography. 相似文献
12.
Chetiyanukornkul T Toriba A Kizu R Kimura K Hayakawa K 《Biomedical chromatography : BMC》2004,18(9):655-661
A simple liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) method for the determination of nicotine and cotinine in human hair was established. In the procedure, a hair sample (10 mg) was washed with dichloromethane and digested in 2.5 M sodium hydroxide. The digest was extracted with dichloromethane and then 25 mM hydrochloric acid in methanol was added to the extract, to prevent loss of analytes. The solution was evaporated and redissolved in the mobile phase, methanol/10 mM ammonium acetate (30/70, v/v). A 20 microL aliquot of redissolved solution was subjected to analysis. Nicotine and cotinine in human hair were quantified by using deuterated analytes as internal standards. The quantification limits were 8 microg/L for nicotine and 0.9 microg/L for cotinine. The proposed method was applied to measure the concentrations of nicotine and cotinine in hair of smokers and non-smokers to evaluate their self-reported smoking and exposure to environmental tobacco smoke. In both cases, the method provided good selectivity, accuracy and precision. 相似文献
13.
Fumiyo Saito Ryo Takeuchi Tomoyuki Kamino Kouji Kuramochi Kengo Sakaguchi Susumu Kobayashi Masashi Tsuda 《Tetrahedron letters》2004,45(43):8069-8071
A total synthesis of the proposed structure of plakevulin A was accomplished. However, the NMR spectral data of the synthetic plakevulin A were not identical of those of the reported compound. We next converted the synthetic plakevulin A into 1-dihydrountenone A. The 1H and 13C NMR spectral data of 1-dihydrountenone A were identical with those of reported plakevulin A except for the peaks derived from levulinic acid. Thus, we repurified sample of the natural product and confirmed that the natural sample contained 1-dihydrountenone A and levulinic acid in the ratio of one to one. We also found that not plakevulin A but 1-dihydountenone A possessed the inhibitory activity against mammalian DNA polymerases α and β. 相似文献
14.
Yoshiyasu Ichikawa Yohei Matsukawa Mari Tamura Fumiyo Ohara Minoru Isobe Hiyoshizo Kotsuki 《化学:亚洲杂志》2006,1(5):717-723
A new method for the synthesis of urea‐linked disaccharides in aqueous media has been developed. The key feature of our approach is two strained Steyermark‐type gluco‐ and galactopyranosyl oxazolidinones. Each oxazolidinone is attached to a pyranose ring in a di‐equatorial trans‐annulation framework. Reaction of these oxazolidinones with 4‐aminohexopyranose in water proceeded smoothly to afford the urea‐tethered cellobiose and lactose analogues. The galactose‐type oxazolidinone proved to be more reactive than the glucose‐type, which is explained by the presence of an axial hydroxy group at C4 in the former. 相似文献
15.
Takeo Katami Tomokuni Hayakawa Masamichi Furukawa Shozo Shibata Tadashi Hara 《Analytica chimica acta》1986
An extraction-spectrophotometric method is described for the determination of traces of zinc with 2-[2-(3,5-dibromopyridyl)azo]-5-dimethylaminobenzoic acid. The reagent forms a stable, blue 1:2 zinc/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the zinc(II) complex is 1.26 × 105 l mol?1 cm?1 at 610 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper and nickel can be masked with dimethylglyoxime and aluminium and iron with a mixture of sodium fluoride and triethanolamine. The method is applied to the determination of zinc in coal fly ash and pond sediments with good precision and accuracy. 相似文献
16.
Methane partial oxidation to formaldehyde with oxygen over SiO2-supported molybdenum oxide catalysts
Hideo Orita Takashi Hayakawa Masao Shimizu Katsuomi Takehira 《Reaction Kinetics and Catalysis Letters》1993,51(1):87-93
The formation rate of formaldehyde increases with increasing surface area of SiO2 support, but the selectivity does not. From the characterization of catalysts using XRD, SEM and Raman spectroscopy, highly dispersed molybdenum oxide was considered to be much more active for the formation of formaldehyde than crystallite forms of MoO3. 相似文献
17.
Nogami Masayuki Nagakura Takehito Hayakawa Tomokatsu Kasuga Toshihiro 《Journal of Sol-Gel Science and Technology》2000,19(1-3):253-256
Persistent spectral hole burning was studied in Eu3+ ions-doped Al2O3-SiO2 glass prepared by a sol-gel method. The gel synthesized by the hydrolysis of Si- and Al-alkoxides and EuCl3·6H2O was heated in air and hydrogen gas atmospheres. For the glass heated in air to contain OH bonds, the hole was formed by the photoinduced rearrangement of the OH bonds surrounding the Eu3+ ions, and was thermally refilled and erased above 200 K. On the other hand, the glass heated in hydrogen gas showed the hole spectrum above 200 K. It was found that the hole depth was independent of the temperature and was 7% of the total intensity at room temperature. The proposed mechanism was the electron transfer between the Eu3+ ions and the defect centers formed in glass matrix. 相似文献
18.
Iida K Hayakawa Y Okamoto H Danjo K Luenbergerb H 《Chemical & pharmaceutical bulletin》2003,51(12):1455-1457
The effect of the surface covering of lactose carrier particles on the dry powder inhalation properties of salbutamol sulfate was investigated. Lactose carrier surfaces were covered with sucrose tristearate (J-1803F) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with various particle surface conditions prepared by surface covering. These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covering lactose carrier were significantly different, showing that the in vitro inhalation properties of salbutamol sulfate were improved. In vitro inhalation properties increased with the percentage of J-1803F added. Using this surface covering system would thus be valuable for increasing the inhalation properties of dry powder inhalation with lactose carrier particles. 相似文献
19.
Influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier 总被引:1,自引:0,他引:1
Iida K Hayakawa Y Okamoto H Danjo K Luenberger H 《Chemical & pharmaceutical bulletin》2004,52(4):444-446
The influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier was investigated. In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with different particle surface conditions prepared by surface covering. Lactose carrier surfaces were covered with vegetable magnesium stearate (Mg-St-V) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covered lactose carrier were little decreased with increased in relative humidity (RH), showing that the in vitro inhalation properties of salbutamol sulfate were improved at high RH. Using this surface covering technique would thus be valuable for storage humidity of dry powder inhalation (DPI) with lactose carrier particles. 相似文献
20.
Reinosuke Hayakawa Toshio Nishi Kunio Arisawa Yasaku Wada 《Journal of Polymer Science.Polymer Physics》1967,5(1):165-177
Thermal expansion and dielectric relaxation of polyacrylonitrile were measured in the temperature range from ?75 to 152°C. at frequencies from 30 cps to 3 Mc./sec. The thermal expansion curve and the temperature dependence of logarithmic relaxation time both show an inflection at 85°C. An x-ray study by Bohn reveals that this inflection comes from the thermal expansion of the paracrystalline phase of this polymer, and consequently the transition at 85°C. and the associated relaxation are ascribed to molecular motion in the paracrystalline phase. The relaxation strength increases with increasing temperature above this point. The transition is caused by freezing of the bending vibration of chains whereas the relaxation results from rotational vibration. The length of segments in this phase is roughly estimated to be ca. 100 A. by comparing the observed relaxation strength with the theory developed on the basis of the above considerations. 相似文献