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471.
Susceptibility effect of intracerebral hematoma was estimated on the phase images of gradient echo (GrE). Thirty-five hematomas were studied 3 hr to 5 yr after the onset, a total of 72 times with use of phase and magnitude images of GrE, as well as T1-, T2-, and density-weighted spin-echo (SE) images at 1.5 T. On the basis of the theory of electromagnetism, phase shift to hematoma was calculated for simplified models with concentric distribution of paramagnetic susceptibility. All hematomas were well visualized by the phase images, the pattern of which changed sequentially. The distribution of paramagnetic susceptibility could be estimated by correlating the observed phase shifts with the calculated one. SE images were necessary to presume the type of magnetic substances. A probable hypothesis of the evolution of intracerebral hematoma is proposed. 相似文献
472.
473.
474.
Yasutoshi Naito Dominique Bourbon Katsuhiko Terada Yoshinori Kamiya 《Journal of Polymer Science.Polymer Physics》1993,31(6):693-697
A previously proposed theoretical treatment to elucidate the pressure dependence of gas permeability is improved in order to apply it to polymer-gas systems in which gas dissolution follows the Flory-Huggins equation. Permeation rates of N2, CH4, and CO2 in poly(ethylene-co-vinyl acetate) are measured in the pressure range below 90 atm at 10–40°C, and the effect of pressure on permeability is found for each gas. The data are analyzed using the improved method to estimate the contributions of concentration and hydrostatic pressure to the pressure dependence of permeability. The concentration effect decreases with increasing temperature, whereas the hydrostatic-pressure effect is almost independent of temperature. Crystallinity dependence of the concentration effect is discussed in connection with high-pressure permeation data of other semicrystalline polymers reported elsewhere. © 1993 John Wiley & Sons, Inc. 相似文献
475.
Yoshinori Kamiya Katsuhiko Terada Yasutoshi Naito Jin-Sheng Wang 《Journal of Polymer Science.Polymer Physics》1995,33(11):1663-1671
Sorption and dilation isotherms and diffusion coefficients for seven hydrocarbons (n-butane, isobutane, 1-butene, cis-2-butene, trans-2-butene, isobutylene, and 1,3-butadiene) in two rubbery polymers, 1,2-polybutadiene (PB) and poly(ethylene-co-vinyl acetate) (EVAc), were measured at 25°C. Dissolution parameters (Henry's law coefficient and Flory-Huggins interaction parameter), partial molar volumes, and diffusion coefficients were determined. PB exhibited greater affinity and lower diffusivity than EVAc to the C4 gases, although the gases showed nearly the same partial molar volumes in the two polymers. The diffusivity of such elongated molecules as trans-2-butene in both polymers was higher than that of bulky molecules with similar partial molar volume, such as cis-2-butene and isobutylene. Pressure-dependent permeabilities of PB and EVAc films to the hydrocarbons were predicted and discussed based on the dissolution parameters and the diffusivities. © 1995 John Wiley & Sons, Inc. 相似文献
476.
Taizo Ono Yoshihisa Inoue Chikara Fukaya Yoshio Arakawa Youichiro Naito Kazumasa Yokoyama Kouichi Yamanouchi Yoshiro Kobayashi 《Journal of fluorine chemistry》1985,27(3):333-346
Electrochemical fluorination of 2-methoxy-1,1,1-trifluoro-2-(F-methyl) octane gave the corresponding perfluorinated ether in 27% yield, along with cyclic by-products in 9%. A mixture of partly fluorinated tertiary amines, consisting of 1-dipropylamino-F-1-propene and 1-dipropylamino-2-hydryl-F-propane, did not afford a superior yield of tri(F-propyl)amine compared to the unfluorinated tripropylamine. 1-Diethylamino-2-(F-methyl)-F-1-pentene was fluorinated to give the corresponding F-tertiary amine in fairly good yields, together with 1-di(F-ethyl)amino-2-hydryl-2-(F-methyl)-F-pentane and their fragmented products. The study indicates that blocking of the α-carbon atom of an ether with F-methyl groups seems to reduce fragmentation, resulting in good yields of an unrearranged product. However, partial fluorination of a tertiary amine prior to electrochemical fluorination rather allows high yields of undesired by-products, as far as our experiments were concerned. 相似文献
477.
Nobuya Katagiri Masayuki Sato Toshihiko Naito Makoto Muto Toshiyuki Sakamoto Satoshi Saikawa Chikara Kaneko 《Tetrahedron letters》1984,25(49):5665-5668
The title compound, a synthetic equivalent of 4-(2-oxoethyl)-azetidin-2-one, has been synthesized as a stable crystalline solid either from 4-(-butyldimethylsilyloxy)- or 4-benzyloxy-2-pyridone photopyridone formation, catalytic hydrogenation, and deblocking of the protecting group. 相似文献
478.
Schülzgen A Kawabe Y Hanamura E Yamanaka A Blanche PA Lee J Sato H Naito M Dan NT Uchida S Tanabe Y Peyghambarian N 《Physical review letters》2001,86(14):3164-3167
Combining linear absorption and nonlinear third harmonic generation (THG) experiments, we investigate details of the electronic structure of the highly correlated electronic system in La2CuO4. We demonstrate strong THG mainly due to the charge transfer excitation from O (2p(sigma)) to Cu (3d(x2-y2)). The THG spectrum shows pronounced features due to three-photon and two-photon resonance enhancement as well as quantum interference effects. We obtain excellent agreement with a THG spectrum calculated in terms of the excitonic cluster model and can identify both odd and even symmetry excitation modes. 相似文献
479.
Gerry Bagtasa Cheng Liu Nobuo Takeuchi Hiroaki Kuze Suekazu Naito Akihiro Sone Hirofumi Kan 《Optical Review》2007,14(1):39-47
Lidar data observed by two continuously operated portable automated lidar (PAL) systems and images from the visible and thermal
infrared channels of the advanced very high resolution radiometer (AVHRR) sensor on board the noaa16 satellite are employed for the characterization of cloud heights and cloud types. The PAL systems are located in Chiba
and Ichihara city areas, separated by approximately 10 km. Measurements from October 2003 to March 2005 reveal that monthly
averages of cloud base height and cloud cover ratio show good agreement between the two sites. The characteristics of the
vertical (Chiba) and slant (Ichihara) measurements are also discussed. The PAL data are used to adjust threshold values of
a cloud-type classification method in split-window data of noaa16-AVHRR. Comparisons between the lidar signals and the cloud classification results from the concurrent AVHRR images show
that the classification method can reasonably be applied to this mid-latitude case, although the split-window technique was
originally developed for tropical clouds. 相似文献
480.
Kawamura I Degawa Y Yamaguchi S Nishimura K Tuzi S Saitô H Naito A 《Photochemistry and photobiology》2007,83(2):346-350
Bacteriorhodopsin (bR) is a retinal protein in purple membrane of Halobacterium salinarum, which functions as a light-driven proton pump. We have detected pressure-induced isomerization of retinal in bR by analyzing 15N cross polarization-magic angle spinning (CP-MAS) NMR spectra of [zeta-15N]Lys-labeled bR. In the 15N-NMR spectra, both all-trans and 13-cis retinal configurations have been observed in the Lys N(zeta) in protonated Schiff base at 148.0 and 155.0 ppm, respectively, at the MAS frequency of 4 kHz in the dark. When the MAS frequency was increased up to 12 kHz corresponding to the sample pressure of 63 bar, the 15N-NMR signals of [zeta-15N]Lys in Schiff base of retinal were broadened. On the other hand, other [zeta-15N]Lys did not show broadening. Subsequently, the increased signal intensity of [zeta-15N]Lys in Schiff base of 13-cis retinal at 155.0 ppm was observed when the MAS frequency was decreased from 12 to 4 kHz. These results showed that the equilibrium constant of [all-trans-bR]/[13-cis-bR] in retinal decreased by the pressure of 63 bar. It was also revealed that the structural changes induced by the pressure occurred in the vicinity of retinal. Therefore, microscopically, hydrogen-bond network around retinal would be disrupted or distorted by a constantly applied pressure. It is, therefore, clearly demonstrated that increased pressure induced by fast MAS frequencies generated isomerization of retinal from all-trans to 13-cis state in the membrane protein bR. 相似文献