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71.
72.
Hisatoyo Morinaga Yusuke Ujihara Naho Yuto Daisuke Nagai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5210-5216
Metal‐free controlled ring‐opening polymerization of glycidyl phenyl ether (GPE) was achieved using tetra‐n‐butylammonium fluoride (Bu4NF) as an initiator in the presence of water and ethanol as chain transfer agents (CTAs). Number‐averaged molecular weight of poly(GPE) increased with an increase of [GPE]0/([Bu4NF]0 + [CTA]0) values, showing relatively narrow molecular weight distributions. NMR spectroscopic analysis exhibited a formation of ethoxy groups as well as FCH2 at the initiating polymer chain‐end when ethanol was used as the CTA in the polymerization. These results indicate that Bu4NF acts as a catalyst as well as the initiator for this polymerization system. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
73.
Effect of refraction index and thickness of the light guide in the position-sensitive gamma-ray detector using compact PS-PMTs 总被引:1,自引:0,他引:1
Koji Inoue Haruo Saito Yasuyuki Nagashima Toshio Hyodo Yasuyoshi Nagai Shinichi Muramatsu Shota Nagai 《Radiation Physics and Chemistry》2000,58(5-6):763-766
We constructed a position-sensitive gamma-ray detector consisting of an array of BGO scintillators, a light guide and compact PS-PMTs. The effects of refractive index and thickness of the light guide of a glass plate on the detector performance were investigated. A light guide with higher refractive index and smaller thickness is found better for a good spatial resolution. 相似文献
74.
Daisuke Nagai Asuka Fujii Masayoshi Tanaka Bungo Ochiai Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2009,47(6):1510-1521
Anionic polymerization of methacrylates under sterically confined environment in a spherical beads‐shaped networked polystyrene (NwPS) matrix is described. The initiator used herein is a samarium (Sm) (III) enolate, which was formed by treatment of 2‐bromoisobutylate immobilized in the side chain of NwPS with Sm (II) iodide. By using this NwPS‐bound initiator, polymerization of a series of methacrylates (=solid‐supported polymerization) was studied to find its two aspects: (1) In the early stages, the rate constant for each methacrylate was comparable to that for its conventional solution‐phase polymerization using a Sm (III) enolate, suggesting that methacrylate can be efficiently supplied to the propagating end by its free permeation without any interference by the networked structure of the matrix. (2) After the early stages, the rate constant decreased remarkably, implying that permeation of methacrylate was sterically interfered by the formed poly(methacrylate) that filled the confined space in NwPS, as supported by a SEM image of the resulting beads, of which pores were filled with the formed polymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1510–1521, 2009 相似文献
75.
H. Nagai N. Oyama H. Yoshie A. Tsujimura 《Journal of magnetism and magnetic materials》1987,70(1-3):171-172
The educed Gd atoms in the X-structure (Th6Mn23-type) of Gd(Fe1−xMnx)2 were magnetically investigated by comparing with Gd6(Fe1−yMny)23 whose structure is Th6Mn23-type. The magnetic properties of Gd(Fe1−xMnx)2 (0.4≤x≤0.7) were observed to be quite similar to those of Gd6(Fe1−yMny)23 (0.4≤y≤0.7). 相似文献
76.
Akira Tanaka Mitsuhiro Fukuda Hiroyuki Nagai Masayuki Shinohara Shigeharu Onogi 《Journal of Polymer Science.Polymer Physics》1989,27(11):2283-2293
A new apparatus was designed to investigate the dynamic viscoelastic properties of solid polymer materials in the nonlinear viscoelastic region. The apparatus was combined with a birefringence apparatus in such a way that birefringence could be measured simultaneously with stress under oscillatory deformation. The nonlinear viscoelastic behavior of bulk-crystallized high-density polyethylene films was examined. Nonlinearity of mechanical properties became evident around 30°C, while optical properties became markedly nonlinear around 50°C. The nonlinearity of viscoelastic properties changes very little when the films are swollen with tetrachloroethane. It is proposed that disruption of lamellae to crystallites in the drawing process is one of the most important causes of the nonlinear behavior of high-density polyethylene films. 相似文献
77.
High-speed, wide-range wavelength scanning is demonstrated using a laser diode with an antireflection coating and an external cavity employing an acousto-optic deflector. The narrow spectral width of 0.2 nm observed in the experiment indicates the availability of a highly coherent laser beam. The scanning range of 15 nm under rapid modulation is confirmed in the prototype system. A tuning rate of more than 100 kHz is achieved without any mode hops. To the best of our knowledge, no such high-speed wavelength tuning based on an acousto-optical configuration has been demonstrated thus far. 相似文献
78.
N. Nakai Y. Nagai M. Machida 《Physica C: Superconductivity and its Applications》2011,471(21-22):743-746
We have performed numerical calculations for low-lying excitations induced by a single non-magnetic impurity in a d-wave superconductor on the basis of two different frameworks. One is the Bogoliubov–de Gennes theory in real coordinates, while the other is the Born approximation in wave-number coordinates. This paper shows that these results for low-lying excitations are identical by using Fourier transformations. 相似文献
79.
Masako Maekawa Haruko Nagai Kayoko Magara 《Colloids and surfaces. A, Physicochemical and engineering aspects》2000,170(2-3):191-198
Mixture diffusion of two dyes (C.I. Direct Blue 15 (DB15) and C.I. Direct Yellow 12 (DY12)) with different affinity onto the substrate into cellulose membrane from the binary solution was studied at 55°C. Uptake curves and concentration–distance profiles were measured experimentally in the ratios (DB15:DY12) 1:0.5, 1:1 and 1:2. It was examined whether the diffusion of the dyes could be analyzed based on the parallel diffusion theory of surface and pore diffusion. It was revealed that the diffusion of DB15 with higher affinity could be analyzed based on the model in the ratios 1:0.5 and 1:1, although the theoretical value deviated slightly from the data in the concentration–distance profile in the ratio 1:1. On the other hand, the diffusion of DY12 with smaller affinity could not be described by the model, because the diffusivity of the dye changed during the adsorption process against the assumption of the model. 相似文献
80.
Makoto Obata Noriko Matsuura Kazunori Mitsuo Hiroki Nagai Keisuke Asai Masafumi Harada Shiho Hirohara Masao Tanihara Shigenobu Yano 《Journal of polymer science. Part A, Polymer chemistry》2010,48(3):663-670
A novel methacrylate monomer bearing 5,10,15,20‐tetraphenylporphyrinato palladium(II) (PdTPP) (monomer 1a ) was synthesized and copolymerized with isobutyl methacrylate (IBM) and 2,2,2‐trifluoroethyl methacrylate (TFEM) to give poly (IBM‐co‐TFEM) bearing PdTPP (copolymer 2a ) as a dye‐conjugated oxygen‐permeable polymer for pressure‐sensitive paint applications. The introduction of PdTPP into copolymer 2a was confirmed by UV–vis spectroscopy and extended X‐ray absorption fine structure analysis. The Stern–Volmer plots of the copolymer 2a and a mixture of PdTPP and poly(IBM‐co‐TFEM) both showed downward curvature, unlike that of the platinum complex analogue (copolymer 2b ) previously reported. The plots were successfully fitted with a two‐site model to give two distinct Stern–Volmer constants (KSV1 and KSV2) and the partition ratio f1. Interestingly, the f1 values for the copolymer 2a were almost constant at about 0.98, whereas those of the mixture of PdTPP and poly(IBM‐co‐TFEM) increased from 0.889 to 0.967 as the temperature was increased. This finding suggests that there are two distinct microheterogeneities, one temperature‐dependent and the other temperature‐independent, in the mixture of PdTPP and poly(IBM‐co‐TFEM). The dye‐conjugation approach effectively eliminates the temperature‐dependent, but not the temperature‐independent microheterogeneity. The luminescence decays of copolymers 2a and 2b and the corresponding mixtures in the absence of oxygen indicated that the temperature‐dependent microheterogeneity involves an oxygen diffusion process, whereas the temperature‐independent one appears to be inherent nature in PdTPP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 663–670, 2010 相似文献