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101.
Takaishi S Kawakami D Yamashita M Sasaki M Kajiwara T Miyasaka H Sugiura K Wakabayashi Y Sawa H Matsuzaki H Kishida H Okamoto H Watanabe H Tanaka H Marumoto K Ito H Kuroda S 《Journal of the American Chemical Society》2006,128(19):6420-6425
We synthesized a novel iodo-bridged linear chain platinum compound, having the quasi-two-dimensional charge-density-wave (CDW) ground state and the smallest band gap. In this compound, we discovered an anomalous valence state in the boundary region at which the CDW phase alternates in the crystal by means of ESR, X-ray diffuse scattering, STM, and electrical resistivity. This anomalous state can be explained by the fast fluctuation between Pt(IV)-I...Pt(II) and Pt(II)...I-Pt(IV) in the double well potential. This is the first observation of the dynamical fluctuation of the CDW phase among the quasi one-dimensional halogen-bridged complexes. 相似文献
102.
In order to reveal mechanisms for the electrospinning of proteins, this study focuses on the polymer chain conformation, which is considered to be a critical factor for successful electrospinning. Poly(gamma-benzyl-L-glutamate) (PBLG) is employed and the relationships between the chain conformations of the pre-spun PBLG molecules and the morphologies of the post-spun PBLG fibers are investigated. By combining viscosity measurements, and circular dichroism and FT-IR spectroscopies, chain conformations of the pre- and post-spun PBLG are characterized. The chain conformations of the pre-spun PBLG changes from an alpha-helix to a random coil upon changing the solvent ratios of dichloromethane (CH(2)Cl(2)) and trifluoroacetic acid (CF(3)COOH) from 100:0 to 0:100. In an alpha-helix conformation, the morphology of PBLG fibers is relatively thick, while that of the random coil is thin and homogenous. The mean fiber diameters decrease when the chain conformations change from an alpha-helix to a random coil. FT-IR spectroscopy and wide-angle X-ray diffraction measurements reveal that electrospinning predominantly induces an alpha-helical conformation in post-spun PBLG fibers, and more highly crystallized fibers are generated as the alpha-helical content in the pre-spun solution increases. 相似文献
103.
Shigeru Matsuo Ken-Ichi Mitsuhashi 《Journal of polymer science. Part A, Polymer chemistry》1994,32(10):1969-1975
Poly(arylene ether ketone)s containing imide units were prepared by the aromatic nucleophilic displacement reaction of the potassium salts of bisphenols with bis(4-fluorobenzoyl)phthalimides in N-methyl-2-pyrrolidone at elevated temperature. The polymers having inherent viscosities of 0.34–0.77 dL/g were obtained in 2 h. The polymers exhibited glass transition temperatures ranging from 216 to 268°C and decomposition temperatures (5% weight loss under air atmosphere) ranging from 450–570°C mainly depending on the bisphenols used in the polymer synthesis. The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'-biphenol- and hydroquinone-based poly(arylene ether ketone imide)s belong to a superior class of heat resistant polymers. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc. 相似文献
104.
Ken-Ichi Yoshikawa 《Mathematische Annalen》2007,337(1):61-89
Let π: X → S be a holomorphic map from a compact Kähler manifold (X,g X ) to a compact Riemann surface S. Let Σπ be the critical locus of π and let Δ = π(Σπ) be the discriminant locus. Let (ξ, h ξ) be a holomorphic Hermitian vector bundle on X. We determine the singularity of the Quillen metric on det Rπ*ξ near Δ with respect to g X | TX/S and h ξ. 相似文献
105.
1st-5th generation poly(propyleneimine) dendrimers having peripheral 2,3-difluorobiphenyl mesogenic groups have been synthesized. They exhibited smectic liquid crystalline behaviour. All the liquid crystalline dendrimers exhibited a smectic A (SmA) phase and a crystal E (E) phase. The SmA-isotropic phase transition temperature increased with increasing generation. In addition, a homeotropic structure was spontaneously formed on a glass plate in the SmA phase for the 2nd, 3rd, and 4th generation dendrimers. The hometropic structure remained unchanged in the phase. 相似文献
106.
We shall present a couple of norm inequalities which will much improve the sharp triangle inequality with n elements and its reverse inequality in a Banach space shown recently by the last three authors. 相似文献
107.
When Cu(110), Ni(l 10), Ag(110) surfaces are exposed to O2 at room temperature, one dimensional metal-oxygen strings grow in the < 001 > direction of the (110) surfaces. A similar phenomenon occurs in the adsorption of H2 on Ni( 110) surface at room temperature, where the one dimensional strings grow along the < 110 > direction. These phenomena are undoubtedly different from the adsorption induced reconstruction but are explained by the chemical reconstruction involving the formation of quasi-compounds and their self-ordering on the metal surfaces. The chemical reconstruction is indispensablly important to understand the structure and catalysis of alloy and bimetallic surfaces. Pt0.25Rh0.75(100) alloy surface being active for the reaction of NO with H2 is an interesting example. When the Pt-Rh(100) alloy surface is exposed to NO or O2 at arround 500 K, a p(3 × 1) ordered Rh-O over-layer is obtained on a Pt-enriched 2nd layer by the chemical reconstruction. Ordering of Rh-0 in the p(3 × 1) structure on the Pt(100) surface was reproduced by heating a Rh/Pt(100) bimetallic surface in O2, and the chemical reconstruction making the p(3 × 1) Rh-O overlayer on a Pt enriched 2nd layer was also proved by heating a Pt/Rh(100) bimetallic surface in O2 or NO. The activation mechanism of the Pt-Rh alloy and the Pt/Rh bimetallic surfaces by the chemical reconstruction was evidently shown by using a Pt deposited Rh(100), Pt/Rh(100), surface. That is, the Pt/Rh(100) is not so active for the reaction of NO with H2, but the reconstructed p(3 × 1)Rh-O/Pt-layer/Rh(100) surface is very active for the reaction. Therefore, it was concluded that the chemical reconstruction of the Pt-Rh catalyst makes the active surface which is composed of Rh-O and a Pt layer. 相似文献
108.
Subratanath Koner Sandip Saha Ken-Ichi Okamoto 《Journal of Physics and Chemistry of Solids》2004,65(4):697-700
A rare asymmetric end-on double-bridged copper (II) azido complex with ∠Cu-N(azide)-Cu=89.1°, has been synthesized and characterized structurally and magnetically. The Cu-N(azide)-Cu angle is unusually low in the complex reported here in comparison to the same in other similar complexes. The magnetic study reveals that the interaction between metal centers in this complex is antiferromagnetic in nature. Though a ferromagnetic interaction between the metal centers is expected in the complex the coupling has actually been found to be antiferromagnetic, instead. 相似文献
109.
Kazuhiro Tanaka Masaaki Okano Hiroyuki Toshino Hidetoshi Kita Ken-Ichi Okamoto 《Journal of Polymer Science.Polymer Physics》1992,30(8):907-914
Permeability and solubility coefficients for H2, CO2, O2, CO, N2, and CH4 in polyimides prepared from 6FDA and methyl-substituted phenylenediamines were measured to investigate effects of the substituents on gas permeability and permselectivity. The methyl substituents restrict internal rotation around the bonds between the phenyl rings and the imide rings. The rigidity and nonplanar structure of the polymer chain, and the bulkiness of methyl groups make chain packing inefficient, resulting in increases in both diffusion and solubility coefficients of the gases. Polyimides from tetramethyl-p-phenylenediamine and trimethyl-m-phenylenediamine display very high permeability coefficients and very low permselectivity due to very high diffusion coefficients and very low diffusivity selectivity, as compared with the other polyimides having a similar fraction of free space. This suggests that these polyimides have high fractions of large-size free spaces. 相似文献
110.
Miyasaka H Madanbashi T Sugimoto K Nakazawa Y Wernsdorfer W Sugiura K Yamashita M Coulon C Clérac R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(27):7028-7040
An alternated 1:1 chain compound of a Mn(III) salen derivative and the TCNQ monoradical was synthesized: [Mn(5-TMAMsaltmen)(TCNQ)](ClO(4))(2) (1) (TCNQ=tetracyano-p-quinodimethane; 5-TMAMsaltmen=N,N'-(1,1,2,2-tetramethylethylene) bis(5-trimethylammoniomethylsalicylideneiminato)). Compound 1 has a zigzag chain structure packed with adjacent chains with an interchain MnMn distance of over 8 Angatrom. As compound 1 contains no crystallization solvent, the void spaces between chains are occupied only by ClO(4) (-) counter ions. Compound 1 has a structure reminiscent of what has been observed in the family of Mn(III)(porphyrin)-TCNE or -TCNQ compounds reported previously by Miller and co-workers and we demonstrate herein its unique single-chain magnet behavior among this family of compounds. The direct current (dc) magnetic measurements established the one-dimensional nature of compound 1 with an antiferromagnetic exchange coupling, J/k(B) approximately -96 K, between the Mn(III) ion and TCNQ radical and with an activated correlation length (Delta(xi)=26.5 K) at low temperatures (50-15 K). The slow relaxation of the magnetization was shown in compound 1 by the field hysteresis of the magnetization observed below 3.5 K (with a coercive field up to 14 kOe at 1.8 K). Single-crystal magnetization measurements demonstrated the uniaxial symmetry of this compound and allowed an estimation of the anisotropy field, H(a) approximately 97 kOe. The absence of magnetic ordered phase or spin-glass behavior was established by heat-capacity calorimetry measurements that exhibit no abnormality of C(p) between 0.5 K and 10 K. The study of the magnetization relaxation by combined ac (alternating current) and dc techniques showed that compound 1 possesses a single relaxation time (tau). As the consequence of the finite size of the chain, the temperature dependence of tau presents two activated regimes above and below 4.5 K with tau(01)=2.1 x 10(-10) s, Delta(tau1)=94.1 K and tau(02)=6.8 x 10(-8) s and Delta(tau2)=67.7 K, respectively. The detailed analysis of these dynamics properties together with the correlation length, allows an unambiguous demonstration of the single-chain magnet behavior in 1. 相似文献