Triton with N---N potential from a quark model

The properties of the three-nucleon bound state are studied employing a nucleon-nucleon potential deduced from the quark cluster model in a five-channel Faddeev calculation. The triton is bound about 0.2–0.3 MeV more than would be expected from conventional meson-exchange models.     

Pyrolysis and mass spectra of trimethylsilyl derivatives of monosaccharides

The pyrolysis of trimethylsilyl derivatives of saccharides (1) was investigated by DTA-TG, MS, GC/MS and TG-GC/MS. The DTA-TG/DTG curves showed that the pyrolysis of 1 occurred in one stage. The exothermic peaks were due to sublimation or thermal decomposition by vaporization. The cleavage mechanism by electron impact of 1 was classified into four categories: 1) stepwise elimination of the side-chain, 2) cleavage of the side-chain, 3) cleavage of the pyranose ring, and 4) cleavage of the pyranose ring and side-chain at the same time. The mass-spectrum for 1 revealed the main common four fragment ions, such asm/z 73, 191, 204 and 217, with cleavage of the pyranose ring. These fragment ions were detected with a similar retention time in the gas cromatogram by GC/MS or TG-GC/MS. The retention time for 1 increased in the sequence aldopentose相似文献   

Design of unique titanium oxide photocatalysts by an advanced metal ion-implantation method and photocatalytic reactions under visible light irradiation

The metal ion-implantation of titanium oxide with various transition metal ions was carried out by applying by high voltage acceleration. The subsequent calcination of the implanted TiO₂ in oxygen at around 723 K resulted in a large shift in the absorption spectra of the TiO₂ toward visible light regions, its extent being dependent on the amount and the kind of metal ions implanted. Such metal ion-implanted titanium oxide catalysts were active in carrying out various photocatalytic reactions such as the decomposition of NO into N₂, O₂ and N₂O at 275 K under irradiation with visible light longer than 450 nm. The application of this advanced, high energy metal ion-implantation method enables the novel design of titanium oxide photocatalysts which can absorb and initiate vital reactions under visible light and will contribute to the development of catalytic systems utilizing solar energy.     

Iridium complex-catalyzed method for the construction of a quaternary carbon center α to allene

[Ir(cod)Cl]₂/dppe-catalyzed allylic alkylation of 1,1-disubstituted-2,3-butadienyl acetates gives a product bearing a quaternary carbon center α to allene in high yield.     

Indirect photometric detection of monovalent cations via postsuppressor ion replacement in microcolumn ion chromatography

Summary Monovalent cations were indirectly detected via postcolumn suppressor ion replacement in microcolumn ion chromatography. The ion-repalcement column loaded by chromophoric ions was connected to the suppressor column. The eluent, nitric acid, was converted to water through the suppressor and anion-replacement columns, while the analyte cations were coeluted with the chromophoric anions. The analyte cations were indirectly detected by measuring UV absorptions of the chromophoric anions.     

Cross section of supercooled238UF6 in multiphoton absorption induced by 16 micrometer Raman-laser radiation

Measurements of multiphoton absorption of 16 µm Raman-laser radiation in supercooled²³⁸UF₆ at 90 K were performed by using a pulsed Laval nozzle with an optical path length of 50 cm. The laser fluence was varied between 50 and 500 mJ/cm² for four frequencies in the range from 625 to 629 cm^–1. The energy absorbed by²³⁸UF₆ molecules was investigated as a function of laser frequency or fluence, and highly accurate results were obtained with the use of the nozzle whose optical path length is much greater than that of nozzles used before. The results indicated that the absorption cross section at the peak absorption frequency (627.8cm^–1) was proportional to the –1/3 power of the fluence.     

Synthesis of multishell fullerenes by laser vaporization of composite carbon targets

Multishell fullerenes are the smallest among multishell carbon clusters, such as the larger graphitic onions or multishell nanotubes. Unlike classical fullerenes, which have a cage structure and are known to have been synthesized in a variety of sizes (C₆₀, C₇₀, C₈₄, C₁₀₂, etc.), multishell fullerenes have a cage-inside-cage concentric structure, such as double-shell C₆₀@C₂₄₀ or triple-shell C₆₀@C₂₄₀@C₅₆₀. We report on the synthesis of multishell fullerenes by laser vaporization of C₆₀-containing composite carbon targets. Transmission electron microscopy, Raman scattering spectroscopy, and other methods were used for characterization of the product. The yield of the process reaches up to 40%, which permits production in gram amounts even in laboratory conditions.     

Inhibitory effects of flavonol glycosides on 12-O-tetradecanoylphorbol-13-acetate-induced tumor promotion

The two-stage carcinogenesis by 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate (TPA) in mice was inhibited by kaempferol and flavonol glycosides, whereas naringenin, a flavanone, had no effect. The induction of epidermal ornithine decarboxylase activity by TPA was also inhibited by kaempferol, whereas mauritianin, a kaempferol glycoside, failed to inhibit it. In addition, the effect of the flavonol glycosides on cell-mediated immunosuppression in the two-stage carcinogenesis, observed in terms of initiation after 14 weeks, was antagonized by mauritianin and myricitrin. Cell-mediated immunosuppression in the two-stage carcinogenesis was unaffected by kaempferol and naringenin. These results suggest that the inhibitory effects of flavonol glycosides may have been at least partly due to activation of immune responses against tumors.     

Dose-dependent enzyme suppression in spleen induced by GM1 (monosialoganglioside 1) administration to mice.

Our previous studies suggested that the administration of exogenous gangliosides to the body modulates enzymatic networks in the brain. In the present study, we tested whether that is the case with another organ, spleen. By testing the dose response relationship, we found that there is a optimum dose for the effect of enzymatic modulation of GM1 (monosialoganglioside 1) administration. Although the optimum level varied depending on each of the examined hydrolytic enzymes, it usually fell in the range around 50 micrograms/kg body weight. The findings led us to conclude that the enzyme-modulating actions of gangliosides come not merely from the bizarre actions in vivo of high molecular exogenous substances.