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An InGaAs/InAlAs five-layer asymmetric coupled quantum well (FACQW) is expected to show very large electrorefractive index change. n in a wideband transparency region. Band structures of the FACQW are analyzed with Luttinger-Kohn Hamiltonian. The electrorefractive characteristics of the FACQW are discussed. 相似文献
3.
Arakawa R Shimomae Y Morikawa H Ohara K Okuno S 《Journal of mass spectrometry : JMS》2004,39(8):961-965
A low molecular mass polyester was analyzed by desorption/ionization on porous silicon (DIOS) mass spectrometry. The results were compared with those of matrix-assisted laser desorption ionization (MALDI) mass spectrometry using matrixes of alpha-cyano-4-hydroxycinnamic acid (CHCA) and 10,15,20-tetrakis(pentafluorophenyl)porphyrin (F20TPP). The CHCA matrix was not suitable for characterization of low molecular mass components of the polyester because the matrix-related ions interfered with the component ions. On the other hand, the F20TPP matrix showed no interference because no matrix-related ions appeared below m/z 822. However, the solvent selection for determining optimal conditions of sample preparation was limited, because F20TPP does not dissolve readily in any of the available organic solvents. In the DIOS spectra, the polymer ions were observed at high sensitivity without a contaminating ion. No matrix is needed for DIOS spectra of low molecular mass polyesters, facilitating sample preparation and selectivity of a precursor ion in post-source decay measurements. 相似文献
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Excitation energies of 123 polycyclic aromatic hydrocarbons were calculated by incorporating the improved method of new-γ for the two-center electron repulsion integral into two semiempirical molecular orbital methods (CNDO/S and INDO/S). This variable method well reproduced experimental excitation energies of them. The average error of the improvement is about 0.162 (CNDO/S) or 0.237 eV (INDO/S) though the average error without the improvement is about 0.541 (CNDO/S) or 0.536 eV (INDO/S). The improvement was useful for the calculations of other organic compounds including hetero atoms, such as organic dye. 相似文献
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T Takamura T Kato E Arakawa S Ogawa Y Suzumura T Kato 《Chemical & pharmaceutical bulletin》1989,37(10):2828-2831
Several analogues substituted with fatty acid at the 2'-, 3'-, or 5'-position of the ribose moiety of N6,N6-dimethyladenosine were synthesized and tested for antitumor activity against cultured cells of L1210 leukemia and/or Ehrlich ascites. The cytotoxicity and increase of life span obtained with congeners in the N6,N6-dimethyladenosine 3'- or 5'-substituted series were comparable to in vitro or several times better in vivo than those of the mother compound. 相似文献
9.
Arakawa Y Ohnishi M Yoshimura N Yoshifuji S 《Chemical & pharmaceutical bulletin》2003,51(8):1015-1020
Synthesis of (1R,2S,5S,6R,8S)-3-azabicyclo[3.3.0]octane-2,6,8-tricarboxylic acid (2) from trans-4-hydroxy-L-proline (5) was attempted. A Diels-Alder reaction of 3,4-dehydroproline derivative 9 and cyclopentadiene afforded a single stereoisomer 11. The Diels-Alder adduct was smoothly converted to the hydrochloride of 2 (24) via RuO(4) oxidation. Although some racemization of the material or product was observed during the synthetic processes, the amino acid 24 proved to be optically pure. 相似文献
10.
Mizooku Y Yoshikawa M Tsuneyoshi T Arakawa R 《Rapid communications in mass spectrometry : RCM》2003,17(16):1915-1918
(-)-Epigallocatechin gallate (EGCG) of catechins changes from non-colored at around neutral pH to yellow at higher pH region in aqueous solution. The pH-dependent oxidation of EGCG was analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS). LC/MS/MS analysis of EGCG and its related compounds, (-)-epicatechin gallate (ECG) and (-)-epigallocatechin (EGC), successfully elucidated the structure relationship of EGCG solution involving the color change reaction at different pH conditions. The oxidation species produced at alkaline pH was detected at a different retention time from EGCG in the chromatograms of the EGCG sample. The oxidation species was found to correspond to M+14 (where M is the molecular weight of EGCG), which has two hydrogen atoms removed and addition of one oxygen atom to the gallyl moiety in the B-ring of EGCG. 相似文献