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181.
Satoshi Yamazaki Kenji Ohoyama Masaki Ichihara Yutaka Ueda 《Journal of solid state chemistry》2010,183(7):1496-1503
V4O9: A missing link of Wadsley phases has been successfully synthesized by using sulfur as a reducing agent at a low temperature and its structure has been determined by combining electron, X-ray and neutron diffractions. V4O9 has an orthorhombic Cmcm structure and the lattice parameters are a=10.356(2) Å, b=8.174(1) Å and c=16.559(3) Å at room temperature. The structure is composed of shared edges and corners of three types of polyhedra; a VO6 distorted octahedron, a VO5 pyramid and a VO4 tetrahedron. The structure of V4O9 is very similar to that of vanadyl pyrophosphate (VO)2P2O7 which has PO4 tetrahedra instead of VO4 tetrahedra. This indicates that V4O9 is a salt of pyro-ion [V2O7]4-; (VO)2V2O7. The magnetic properties of V4O9 have been investigated by magnetic susceptibility, high-field magnetization and inelastic neutron scattering measurements. V4O9 is a quantum spin system with a spin-gapped ground state. The excitation gap between the singlet ground state and the excited triplet state is approximately 73 K. The magnetic susceptibility behavior suggests that V4O9 is a spin-1/2 dimer system with significant interdimer interactions, as opposed to (VO)2P2O7, which is an alternating spin-1/2 chain system. This difference is thought to be due to the fact that VO4-mediated interactions are considerably weaker than PO4-mediated interactions. 相似文献
182.
David M. Hodgson Matthew L. Jones Andrew R. Cowley Osamu Ichihara 《Tetrahedron》2009,65(37):7825-6337
Additions of alkyl or aryl Grignard reagents, or pyridin-3-yl-lithiums or lithium alkoxides, to exo-5,6-epoxy-7-(tert-butoxycarbonyl)-2-tosyl-7-azabicyclo[2.2.1]hept-2-ene lead to 7-substituted-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols. Radical deoxygenations of 7-alkyl-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols give 7-alkyl-4-tosyl-2-azabicyclo[2.2.1]hept-5-enes, whereas 7-aryl-1-tosyl-3-azatricyclo[2.2.1.02,6]heptan-5-ols give 2-(arylmethyl)-5-tosyl-1,2-dihydropyridines. 相似文献
183.
Ichihara C Kawakami N Yasuno S Hino A Fujikawa K Kobayashi A Ochi M Gotoh H Kugimiya T 《Micron (Oxford, England : 1993)》2009,40(1):66-69
High-resolution Rutherford backscattering spectrometry (HRBS) in combination with grazing angle argon sputtering was carried out to characterize the interface of aluminum-nickel (Al-Ni) alloy and amorphous-silicon films in a thin film transistor (TFT) for liquid crystal display (LCD). After thinning the top Al-Ni layer by a 1-keV Ar sputtering, the sensitivity of the interface oxygen was improved to be twice higher than that before sputtering. The results revealed that the oxygen at the interface relates to the contact characteristics. 相似文献
184.
185.
186.
Mie KodaniAyumi Takamori Kazuo TakimiyaYoshio Aso Tetsuo Otsubo 《Journal of solid state chemistry》2002,168(2):582-589
Seven conductive radical cation salts based on MDSe-TSF (methylenediselenotetraselenafulvalene) have been synthesized by electrocrystallization in the presence of Cl−, Br−, I3−, I2Br−, PF6−, ClO4−, and Cu(NCS)2− counter anions. The crystal appearances of these salts fairly depend on the anions employed. X-ray crystallographic analyses have revealed that the PF6 and ClO4 salts in the shape of brown thin plates adopt the θ-type structures characterized by the herringbone arrangement of donor stacks, whereas the Cl and Br salts in the shape of black thick plates favor the κ-type structures with the orthogonal arrangement of donor dimers. Regardless of different crystal appearances or crystal packing patterns, all these salts show high conductivity (>102 S cm−1) at room temperature and retain metallic properties down to 4.2 K. Of them, the Br salt shows a weak but distinct diamagnetic shielding signal below 4 K in the dc magnetization measurement under zero-field-cooled (ZFC) condition, suggesting a sign of superconductivity. The band calculations of both PF6 and Br salts demonstrate closed Fermi surfaces indicative of two-dimensional molecular conductors. 相似文献
187.
Dr. Mie Andersen Dr. Andrew J. Medford Prof. Jens K. Nørskov Prof. Dr. Karsten Reuter 《Angewandte Chemie (International ed. in English)》2016,55(17):5210-5214
Bifunctional coupling of two different catalytic site types has often been invoked to explain experimentally observed enhanced catalytic activities. We scrutinize such claims with generic scaling‐relation‐based microkinetic models that allow exploration of the theoretical limits for such a bifunctional gain for several model reactions. For sites at transition‐metal surfaces, the universality of the scaling relations between adsorption energies largely prevents any improvements through bifunctionality. Only the consideration of systems that involve the combination of different materials, such as metal particles on oxide supports, offers hope for significant bifunctional gains. 相似文献
188.
189.
Assessment of T1 time course changes and tissue-blood ratios after Gd-DTPA administration in brain tumors 总被引:1,自引:0,他引:1
K Yoshida M Furuse Y Kaneoke K Saso S Inao Y Motegi K Ichihara A Izawa 《Magnetic resonance imaging》1989,7(1):9-15
Sequential T1 changes in brain tumor tissue after Gd-DTPA administration were investigated in 10 patients, including 4 meningiomas, 2 gliomas, 3 metastatic cerebral tumors and 1 brain abscess. T1 values were measured serially for 60 minutes following Gd-DTPA injection using a magnetic focusing technique. In vitro T1 of the whole blood samples was also comparatively examined. Time processes in the tissue-blood ratio (TBR) were calculated from two-point relaxation rates at 5 and 30 minutes. The obtained ratios of TBR were ranged from 1.0 to 3.0, probably depending on histological types of brain tumor (the value of 1.0 to 1.5 for meningioma and 1.5 to 3.0 for glioma and metastatic tumor). No significant changes in the T1 value were observed in the examined normal tissue and peritumoral edema. These results indicate that Gd-DTPA plays an important role not only as an image enhancer for tumor tissue but also as an indicator for estimating the blood-brain barrier function. 相似文献
190.
Miyuki Takei Yoshiharu Tsujita Shigetaka Shimada Hisakatsu Ichihara Motohiro Enokida Akira Takizawa Takatoshi Kinoshita 《Journal of Polymer Science.Polymer Physics》1988,26(5):997-1008
The ionic interaction of poly(ethylene-co-methacrylic acid) ionomer neutralized with Mn2+ or Cu2+ was studied by ESR spectroscopy to explore the local structure in the ionic aggregate. ESR spectra of the ethylene ionomer were obtained as functions of degree of neutralization and temperature. The existence of both isolated and aggregated cations in the ionomer was confirmed by ESR. In addition, the formation of a Cu2+?Cu2+ dimer structure similar to the crystal structure of copper acetate monohydrate was found in ethylene ionomer containing the Cu2+. Cation-cation interactions changed markedly around 70°C with increasing temperature, representing the onset of the motion of cations in the aggregated ionic structure. 相似文献