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排序方式: 共有677条查询结果,搜索用时 15 毫秒
1.
Tomohiro Kyotani Sonoko Kakui Takehito Mizuno Naoto Shimotsuma Soushi Inoue Junji Saito 《Analytical sciences》2006,22(7):1031-1034
A zeolite NaA (LTA) membrane supported by an alumina porous support tube for pervaporation (PV) dehydration of ethanol was characterized by transmission electron microscopy (TEM) using a focused ion beam (FIB) thin-layer specimen preparation technique and by Fourier transform infrared attenuated total reflectance method (FTIR-ATR) using a diamond prism as the waveguide. FIB-TEM clearly presented cross-section images up to about 15 microm depth from the membrane surface. FTIR-ATR monitored the Si-O asymmetric stretching vibration spectrum. The Si-O spectrum was compared with the TEM image and their relationships were discussed. By combining the two methods, we could study the thickness of surface LTA crystals, the grain boundary, the LTA/alumina interface structure and the crystallinity and density of materials inside of the alumina porous support. Consequently, fine structure changes of the LTA membrane corresponding to the hydrothermal synthesis condition could be sensitively detected. 相似文献
2.
Shigeru Katayama Mika Horiike Kazuyuki Hirao Naoto Tsutsumi 《Journal of Polymer Science.Polymer Physics》2002,40(24):2800-2806
We investigated the structures induced by an irradiation of a near‐infrared (NIR) femtosecond laser pulse in dye‐doped polymeric materials {poly(methyl methacrylate) (PMMA), thermoplastic epoxy resin (Epoxy), and a block copolymer of methyl methacrylate and ethyl acrylate‐butyl acrylate [p(MMA/EA‐BA) block copolymer]}. Dyes used were classified into two types—type 1 with absorption at 400 nm and type 2 with no absorption at 400 nm. The 400‐nm wavelength corresponds to the two‐photon absorption region by the irradiated NIR laser pulse at 800 nm. Type 1 dye‐doped PMMA and p(MMA/EA‐BA) block copolymer showed a peculiar dye additive effect for the structures induced by the line irradiation of a NIR femtosecond laser pulse. On the contrary, dye‐doped Epoxy did not exhibit a dye additive effect. The different results among PMMA, p(MMA/EA‐BA) block copolymer, and Epoxy matrix polymers are supposed to be related to the difference of electron‐acceptor properties. The mechanism of this type 1 dye‐additive‐effect phenomenon for PMMA and p(MMA/EA‐BA) block copolymer is discussed on the basis of two‐photon absorption of type 1 dye at 400 nm by the irradiation of a femtosecond laser pulse with 800 nm wavelength and the dissipation of the absorbed energy to the polymer matrix among various transition processes. Dyes with a low‐fluorescence quantum yield favored the formation of thicker grating structures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2800–2806, 2002 相似文献
3.
In this paper a form of the Lindeberg condition appropriate for martingale differences is used to obtain asymptotic normality of statistics for regression and autoregression. The regression model is yt = Bzt + vt. The unobserved error sequence {vt} is a sequence of martingale differences with conditional covariance matrices {Σt} and satisfying supt=1,…, n
{v′tvtI(v′tvt>a) |zt, vt−1, zt−1, …}
0 as a → ∞. The sample covariance of the independent variables z1, …, zn, is assumed to have a probability limit M, constant and nonsingular; maxt=1,…,nz′tzt/n
0. If (1/n)Σt=1nΣt
Σ, constant, then √nvec(
n−B)
N(0,M−1Σ) and
n
Σ. The autoregression model is xt = Bxt − 1 + vt with the maximum absolute value of the characteristic roots of B less than one, the above conditions on {vt}, and (1/n)Σt=max(r,s)+1(Σtvt−1−rv′t−1−s)
δrs(ΣΣ), where δrs is the Kronecker delta. Then √nvec(
n−B)
N(0,Γ−1Σ), where Γ = Σs = 0∞BsΣ(B′)s. 相似文献
4.
The anomalous Hall effect due to the spin chirality order and fluctuation is studied theoretically in a Kondo lattice model without the relativistic spin-orbit interaction. Even without the correlations of the localized spins, sigma(xy) can emerge depending on the lattice structure and the spin anisotropy. We reveal the condition for this chirality-fluctuation driven mechanism for sigma(xy). Our semiquantitative estimates for a pyrochlore oxide Nd2Mo2O7 give a finite sigma(xy) approximately equal 10 Omega(-1) cm(-1) together with a high resistivity rho(xx) approximately equal 10(-4)-10(-3) Omega cm, in agreement with experiments. 相似文献
5.
The paper presents the first report on χ(2) polarization induced in molecular glass of conjugated compound by all-optical poling. Transparent thin film of molecular glass of 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene (BTAPVB) was prepared using a spin-cast technique. Dipolar as well as octupolar components in BTAPVB contributed to the formation of photoinduced χ(2) polarization. Growth rate of χ(2) polarization has good linear relation with Eω4E2ω, which suggested that the simultaneous processes of two-photon (ω + 2ω) and three-photon (ω + ω + ω) excitation on the same electronic level contributed to the formation of photoinduced χ(2) polarization. 相似文献
6.
Mott's metal-insulator transition at an interface due to band bending is studied by the density matrix renormalization group approach. We show that the result can be recovered by a simple modification of the conventional Poisson's equation approach used in semiconductor heterojunctions. A novel mechanism of colossal electroresistance is proposed, which incorporates the hysteretic behavior of the transition in higher dimensions. 相似文献
7.
Watanabe Hayato Omura Takuya Okaichi Naoto Kano Masanori Sasaki Hisayuki Arai Jun 《Optical Review》2022,29(4):366-374
Optical Review - Light field displays can display three-dimensional (3D) images with smooth motion parallax without the use of special glasses, by reproducing light ray information from objects.... 相似文献
8.
Yusuke Hamabe Sungbong Jung Hikotaro Suzuki Naoto Koizumi Muneyoshi Yamada 《Journal of synchrotron radiation》2010,17(4):530-539
Ni species on the spent NiMo catalyst from ultra‐deep hydrodesulfurization of gas oil in a commercial plant were studied by Ni K‐edge EXAFS and TEM measurement without contact of the catalysts with air. The Ni–Mo coordination shell related to the Ni–Mo–S phase was observed in the spent catalyst by quasi in situ Ni K‐edge EXAFS measurement with a newly constructed high‐pressure chamber. The coordination number of this shell was almost identical to that obtained by in situ Ni K‐edge EXAFS measurement of the fresh catalyst sulfided at 1.1 MPa. On the other hand, large agglomerates of Ni3S2 were observed only in the spent catalyst by quasi in situ TEM/EDX measurement. MoS2‐like slabs were sintered slightly on the spent catalyst, where they were destacked to form monolayer slabs. These results suggest that the Ni–Mo–S phase is preserved on the spent catalyst and Ni3S2 agglomerates are formed by sintering of Ni3S2 species originally present on the fresh catalyst. 相似文献
9.
Electric polarization in insulators is represented by the transferred charge through a shift of the Bloch wave functions induced by an adiabatic change of external parameters Q-->. It is found that this covalent/quantum contribution is determined nonlocally by the topological structure in the Q--> space. The condition for the charge pumping for a cyclic change of Q--> is also obtained. Applications of this picture to various organic ferroelectrics and BaTiO3 are discussed. 相似文献
10.
Anion photoelectron spectroscopy of acetonitrile cluster anions, (CH3CN)(-)(n) (n=10-100), successfully demonstrates the competitive coexistence of two different anionic species: a solvated electron and a solvent-bound valence anion. The distinctly different nature of these anions is revealed by hole-burning-type photoelectron spectroscopy and relative photodetachment cross section measurements. This unusual coexistence is attributed to the closely lying nature of their anionic states at just the number of solvent molecules sufficient to almost complete the first solvation layer. 相似文献