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91.
92.
Nuclear magnetic resonance studies of alkaline earth phosphosilicate and aluminoborosilicate glasses
Hiroshi Yamashita Hidetake Yoshino Keishi Nagata Hyuma Inoue Takeshi Nakajin Takashi Maekawa 《Journal of Non》2000,270(1-3):48-59
The 11B, 27Al, 29Si and 31P magic angle spinning (MAS) NMR spectra of MO–P2O5, MO–SiO2–P2O5 and MO(M′2O)–SiO2–Al2O3–B2O3 (M=Mg, Ca, Sr and Ba, M′=Na) glasses were examined. In binary MO–P2O5 (M=Ca and Mg) glasses, the distributions of the phosphate sites, P(Qn), can be expressed by a theoretical prediction that P2O5 reacts quantitatively with MO. In the ternary 0.30MO–0.05SiO2–0.65P2O5 glasses, the 6-coordinated silicon sites were detected, whose population increases in the order of MgOxCaO–0.05SiO2–(0.95−x)P2O5 glasses, its population increases with an increase in f (=([P2O5]−[MO]−[B2O3]−[Na2O])/[SiO2]) and has maximum at f=9. The signal due to the 5-coordinated silicon atoms is also observed when x is smaller than 0.45. When three network-forming oxides such as SiO2, Al2O3 and B2O3 coexist, Al2O3 reacts preferably with MO. The populations of 4-coordinated boron atoms, N4, are expressed well with r/(1−r), where r=([Na2O]−[Al2O3])/([Na2O]−[Al2O3]+[B2O3]). The correlation of the Raman signal at 1210 and 1350 cm−1 with the NMR signal of Si(Q6) at −215 ppm is also seen. 相似文献
93.
Katsuhiro Saito Yoichi Omura Etsuro Maekawa Paul G. Gassman 《Tetrahedron letters》1984,25(24):2573-2576
Addition reactions of cyclooctatetraene with 1,3-diphenylisobenzofuran resulted in the formation of three 1:1 cycloadducts, 1, 2, and 3, and a 1:2 cycloadduct, 4. Single crystal x-ray analysis established 3 to be a cage compound formed by an unprecedented [4+2] cycloaddition reaction of 1 in which the double bond of the benzene moiety acted as the dienophile. 相似文献
94.
Hideki Maekawa Kotaro Kawata Yue Ping Xiong Natsuko Sakai Harumi Yokokawa 《Solid State Ionics》2009,180(4-5):314-319
Local coordination structure around Yttrium ions in CeO2–Y2O3 binary and [(CeO2)x(ZrO2)1?x]0.8(YO1.5)0.2 (x = 0.0 ~ 1.0) ternary system has been investigated by 89Y MAS-NMR. NMR spectra are found to be consisted of multiple peaks that can be assigned to 6-, 7- and 8-oxygen coordinated Yttrium ions. Compositional dependence of the spectrum was observed and compared with the previous results for ZrO2–Y2O3 binary system. The present investigation suggested the degree of localization of the oxygen vacancy around the cation is in the order of Zr4+ > Y3+ > Ce4+. The degree of the oxygen vacancy preference for each cation was quantitatively determined for CeO2–ZrO2–Y2O3 ternary system the first time. 相似文献
95.
Guo‐Qing Bian Takayoshi Kuroda‐Sowa Hisashi Konaka Masahiko Maekawa Megumu Munakata 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):m338-m340
The title compound, [Mn2(μ‐O)(C6H3NO3)2(C5H5N)4]·H2O, was isolated from the reaction of 2,6‐pyridinedicarboxylic acid with [Mn12O12(CH3COO)16(H2O)4] in pyridine. The dimanganese complex has twofold symmetry; the MnIII atoms are bridged by one oxo and two amidate ligands and show compressed octahedral Jahn–Teller distortion. The molecular packing comprises a three‐dimensional structure constructed by means of extensive intermolecular interactions, including three kinds of hydrogen bonds and π–π interactions. 相似文献
96.
Yasunori Maekawa 《Journal of Mathematical Analysis and Applications》2009,349(1):181-200
Axisymmetric or non-axisymmetric Burgers vortices have been studied numerically as a model of concentrated vorticity fields. Recently it has been rigorously proved that non-axisymmetric Burgers vortices exist for all values of the vortex Reynolds number if an asymmetry parameter is sufficiently small. On the other hand, several numerical results indicate that Burgers vortices have simpler structures as the vortex Reynolds number is increasing, even when the asymmetry parameter is not sufficiently small. In this paper we give a rigorous explanation for this numerical observation and extend the existence and stability results of Burgers vortices for high vortex Reynolds numbers. 相似文献
97.
Mg-promoted reductive coupling of aromatic carbonyl compounds (1) with chlorosilanes, such as trimethylsilyl chloride (TMSCl:2), 1,2-bis(chlorodimethylsilyl)ethane (3) and 1,5-dichlorohexamethyltrisiloxane (4), in N,N-dimethylformamide (DMF) at room temperature brought about selective and facile reductive formation of both of carbon-silicon and oxygen-silicon bonds to give the corresponding α-trimethylsilylalkyl trimethylsilyl ethers (5) and cyclic siloxanes (6), (7) in moderate to good yields, respectively. The present facile and selective coupling may be initiated through electron transfer from Mg metal to aromatic carbonyl compounds (1). 相似文献
98.
1H-1,2,3-triazole,a promising precursor for chemical vapor deposition of hydrogenated carbon nitride
Md. Nizam Uddin Iqbal Ahmed Siddiquey Md. Jahurul Islam Osama A. Fouad Masamitsu Nagano 《Journal of Crystal Growth》2009,311(13):3528-3532
Well-crystallized hydrogenated carbon nitride thin films have been prepared by microwave plasma enhanced chemical vapor deposition (MWPECVD). 1H-1,2,3-triazole+N2 and Si (1 0 0) were used as precursor and substrate, respectively. Substrate temperature during the deposition was recorded to be 850 °C. The synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photo-electron spectroscopy (XPS) analyses. The plasma compositions were checked by optical emission spectroscopy (OES). XRD observation strongly suggests that the films contain polycrystalline carbon nitride with graphitic structure of (1 0 0), (0 0 2), (2 0 0) and (0 0 4). XPS peak quantification reveals that the atomic ratio of the materials C:N:O:Si is 32:41:18:9. X-ray photo-electron peak deconvolution shows that the most dominant peak of C (1s) and N (1s) narrow scans correspond to sp2 hybrid structure of C3N4. These observations indicate that 1H-1,2,3-triazole favors the formation of hydrogenated carbon nitride with graphitic phase by CVD method and thus is in good agreement with XRD results. SEM of surface and OES of plasma also support the formation of polycrystalline carbon nitride films from 1H-1,2,3-triazole+N2 by CVD. 相似文献
99.
Chiral 2-piperidinone compounds with various C-6 substituents were successfully synthesized via a Pd-catalyzed asymmetric 6-endo cyclization of dienamides, which were evidently activated by both N-p-toluenesulfonyl and C-3 ester substituents. 相似文献
100.
Recently, the Voice Handicap Index (VHI), developed in the United States, has been highlighted as a means to assess a patient's perceptions of the severity of his or her voice disorder. The VHI is based on a self-administered questionnaire that quantifies the degree of a patient's disability related to his/her voice disorder. The questionnaire was translated into Japanese and applied to Japanese patients with various kinds of disordered voice or dysphonia. The results were analyzed and the usefulness discussed. In this study, 546 patients (281 males and 265 females) were included. Mean VHI scores were 36.2/120 in males and 44.1/120 in females. In the male patients, VHI scores were the highest among teens. However, VHI scores did not vary with age in the female patients. Patients with vocal fold paralysis, functional dysphonia, psychological dysphonia, and spasmodic dysphonia showed relatively high VHI scores, whereas those with laryngeal granuloma and laryngopharyngeal reflux disease showed low scores. In most diseases, functional and physiological scores were higher than emotional scores. In any treated patients, those with vocal nodule, vocal polyp, polypoid vocal fold, and recurrent laryngeal nerve paralysis, VHI scores decreased after therapeutic intervention. These findings suggest that the Japanese VHI is a useful tool for monitoring a patient's psychological status, choosing appropriate treatment, and assessing the therapeutic outcome. 相似文献