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101.
Ko Sugihara 《Journal of Physics and Chemistry of Solids》1973,34(10):1727-1736
Thermoelectric power in antiferromagnetic semiconductors is calculated in the vicinity of the Néel temperature by assuming the presence of the well-defined propagating modes (magnon) and a temperature-dependent magnon velocity. Carriers are specified by the mobile carriers in a broad band with an isotropic effective mass. Magnons and carriers are coupled via the sd-interaction. Anomaly near TN does not result from the diffusion term Sdiff. and it is ascribed to the magnon-drag contribution Sdrag which is obtained from,where R(q) is the momentum transfer ratio between the magnon system and carriers, cm(q) denotesthe specific heat of the magnon q. The assumed temperature dependence of the magnon velocity makesSdru divergent at TN with TN ? T → +0 and it might be removed in consideration of the magnon frequency spreading. Except this divergence the calculation provides a qualitative explanation for the anomalous feature in MnTe. 相似文献
102.
103.
104.
Nakayama J Aoki S Takayama J Sakamoto A Sugihara Y Ishii A 《Journal of the American Chemical Society》2004,126(29):9085-9093
5,6-Di-tert-butyl-2,3,7-trithiabicyclo[2.2.1]hept-5-ene 7-endo-oxide (4) was prepared by addition of S(2)Cl(2) to 3,4-di-tert-butylthiophene 1-oxide (3) in high yield. The oxidation of 4 with dimethyldioxirane gave a 7:1 isomeric mixture of 5,6-di-tert-butyl-2,3,7-trithiabicyclo[2.2.1]hept-5-ene 2-endo-7-endo-dioxide (5a) and 2-exo-7-endo-dioxide (5b) quantitatively. The thermally labile 5 was shown to undergo a retro-Diels-Alder reaction that produces S(2)O and 3 in a reversible way. The resulting S(2)O was trapped by Diels-Alder reactions with dienes to give 3,6-dihydro-1,2-dithiin 1-oxides in good yields. In the absence of the dienes, S(2)O disproportionates to SO(2) and S(3), and the resulting S(3) underwent a 1,3-dipolar cycloaddition with 3 on its syn-pi-face with respect to the S[double bond]O bond to give a trithiolane derivative, whereas in the presence of excess norbornene, it produced the 1,3-dipolar cycloadduct with norbornene in good yield. Thus, the retro-Diels-Alder reaction of 5 functions as an S(2)O and S(3) source. DFT calculations at the B3LYP/6-311+G(3df,2p) level were carried out in order to explain why S(2)O disproportionates to SO(2) and S(3) and why S(2)O acts as a dienophile and not a 1,3-dipole, whereas O(3) and S(3) serve as 1,3-dipoles. 相似文献
105.
Sugihara T Kuwahara K Wakabayashi A Takao H Imagawa H Nishizawa M 《Chemical communications (Cambridge, England)》2004,(2):216-217
Nitric oxide reacts efficiently with alkynyllithium at low temperature producing 1,2,3-oxadiazole 3-oxides in good yields. 相似文献
106.
107.
We give a geometric framework for analysing iterative methods on singular linear systems A x = b and apply them to Krylov subspace methods. The idea is to decompose the method into the ?(A) component and its orthogonal complement ?(A)?, where ?(A) is the range of A. We apply the framework to GMRES, GMRES(k) and GCR(k), and derive conditions for convergence without breakdown for inconsistent and consistent singular systems. The approach also gives a geometric interpretation and different proofs of the conditions obtained by Brown and Walker for GMRES. We also give examples arising in the finite difference discretization of two‐point boundary value problems of an ordinary differential equation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
108.
Multifunctional Core–Shell Silica Nanoparticles for Highly Sensitive 19F Magnetic Resonance Imaging 下载免费PDF全文
Hisashi Matsushita Dr. Shin Mizukami Dr. Fuminori Sugihara Yosuke Nakanishi Prof. Yoshichika Yoshioka Prof. Kazuya Kikuchi 《Angewandte Chemie (International ed. in English)》2014,53(4):1008-1011
19F magnetic resonance imaging (19F MRI) is useful for monitoring particular signals from biological samples, cells, and target tissues, because background signals are missing in animal bodies. Therefore, highly sensitive 19F MRI contrast agents are in great demand for their practical applications. However, we have faced the following challenges: 1) increasing the number of fluorine atoms decreases the solubility of the molecular probes, and 2) the restriction of the molecular mobility attenuates the 19F MRI signals. Herein, we developed novel multifunctional core–shell nanoparticles to solve these issues. They are composed of a core micelle filled with liquid perfluorocarbon and a robust silica shell. These core–shell nanoparticles have superior properties such as high sensitivity, modifiability of the surface, biocompatibility, and sufficient in vivo stability. By the adequate surface modifications, gene expression in living cells and tumor tissue in living mice were successfully detected by 19F MRI. 相似文献
109.
Hirofumi Totsuka Takashi Sugihara Takashi Mizuochi Hiroshi Kubo Hitoyuki Tagami Kuniaki Motoshima 《光学学报》2003,23(Z1)
A numerical simulation shows that by using electronic equalizers 1 bit/s/Hz spectral efficiency can be attained with the same signal quality as a 0.8 bit/s/Hz system. Waveform distortion due to optical band-limiting is corrected with nearly 3 dB improvement of the Q-penalty. 相似文献
110.
Yasuhiro Matsuda Yuji Miyazaki Shinji Sugihara Sadahito Aoshima Kazuya Saito Takahiro Sato 《Journal of Polymer Science.Polymer Physics》2005,43(20):2937-2949
Cloud‐point and binodal curves of the LCST type were obtained for aqueous solutions of a thermoresponsive polymer, poly [2‐(2‐ethoxy)ethoxyethyl vinyl ether], poly(EOEOVE). The cloud‐point curve obtained was very flat except in a dilute region, that is the cloud‐point temperature was insensitive to the polymer concentration, resembling the cloud‐point curve for aqueous solutions of poly(N‐isopropylacrylamide). On the other hand, the binodal curve obtained was parabolic, and located within the two‐phase region of the cloud‐point curve. Accompanied with the phase separation, a sharp endothermic peak was observed in a region including the cloud‐point and binodal temperatures. The reciprocal of the osmotic compressibility ?Π/?c obtained by sedimentation equilibrium indicated that water changes from a good to poor solvent for poly(EOEOVE) with increasing temperature. Analyzing the ?Π/?c data by a thermodynamic perturbation theory, we determined the interchain interaction parameters, the hard‐core diameter d and the depth ε of the square‐well potential. Theoretical binodal and endothermic curves calculated by the perturbation theory using the estimated interaction parameters reproduced experimental ones semiquantitatively, but the theoretical binodal disagreed with the experimental flat cloud‐point curve. The disagreement at high concentrations was in the opposite direction to that expected from the sample polydispersity in the molecular weight. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2937–2949, 2005 相似文献