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排序方式: 共有57条查询结果,搜索用时 12 毫秒
1.
Sadao Hayashi Toshihiro Hirai Sonoko Shimomichi Nobumasa Hojo 《Journal of polymer science. Part A, Polymer chemistry》1982,20(3):839-846
Polyiodide formed by complexation of poly(vinyl acetate) (PVAc) with iodine in the presence of iodide has been investigated by chemical analysis and resonance Raman spectrophotometry. When PVAc films were immersed in iodide-iodine aqueous solutions which had different ratios of iodide to iodine concentration [I?]/[I2], the complex films exhibited tremendous variations of swelling degree, despite the relatively small change in the amount of bound iodine. From a quantitative chemical analysis, the composition of polyiodide bound to PVAc was found to be 1.01 ± 0.035 in the molar ratio of iodide to iodine irrespective of the composition of the iodide-iodine aqueous solution ([I?]/[I2] = 2–500). The polyiodide formed in PVAc-iodine-iodide complex was therefore inferred to be (I3?)n. Resonance Raman spectra obtained on PVAc-iodine-iodide complexes were also identical to those of the benzamide-iodine complex, in which the polyiodide consists of (I3?)n, consistent with the result from chemical analysis. 相似文献
2.
Reactions of Ph(2)C(3) dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with alkyl thiocyanates or alkane dithiocyanates gave 1,3-bis(alkylthio)allenes 1 or tetrathiacyclic bisallenes 2, respectively. Thermal reactions of 1 gave thiophenes 4 and 7, benzothiepin 5, 1,2-bis(benzylidene)cyclobutane 6, thiete 8, and alpha,beta-unsaturated ketone 9, and the reactions of tetrathiacyclic bisallenes 2a gave a cyclic dimer, 1,2-bis(benzylidene)cyclobutane derivative 10, quantitatively. Irradiation of 1,3-bis(alkylthio)allenes 1 and tetrathiacyclic bisallenes 2a caused rearrangement to give alkynes 18, 20, and 21. In the irradiation of the cyclic bisallenes 2a, isomerizations from dl to meso and meso to dl isomers were also found. In the reactions of allenes 1 and cyclic bisallenes 2a with diphenyl diazomethane, the diazomethane reacted selectively with the double bond rather than with the sulfur atom. 相似文献
3.
Nobumasa Kamigata 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4):667-678
Abstract The synthesis and stereochemistry of tricoordinated optically active selenium and tellurium compounds are described. Telluronium salts, telluronium imides, and seleninic acids were prepared and optically resolved by fractional recrystallization of diastereomeric mixtures or by chromatography using a chiral column of racemic mixtures. Diphenyl dichalcogenides also were optically resolved by chiral crystallization. Their absolute configurations were determined or estimated based on X-ray crystallographic analysis, specific rotations, and circular dichroism spectra. The kinetic studies and the mechanism for the racemization were also studied. 相似文献
4.
Toshio Shimizu Kazuko Iwata Hideyuki Murakami Nobumasa Kamigata 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):457-458
Sulfur-containing cycloalkenes possessing disulfide units 1, 2, and 3 were obtained by oxidation of cis-disodium ethene-1,2-dithiolate, and their crystal structures were determined by the X-ray crystallographic analyses. Compound 1 was found to give the ring expansion product 3 in acetonitrile even at room temperature and also form reactive thioaldehyde under irradiation. 相似文献
5.
Steady-progressive-wave solutions are sought to the nonlinear wave equation derived previously [J. Fluids Struct. 16 (2002) 597] for flexural motions of an elastic beam traveling in an air-filled tube along its center axis at a subsonic speed. Fluid-structure interactions are taken into account through aerodynamic loading on the lateral surface of the beam subjected to small but finite deflection but end effects and viscous effects are neglected. Linear dispersion characteristics are first examined by exploiting the small ratio of the induced mass to the mass of the beam per unit length. Centered around the traveling speed of the beam, there exists such a narrow range of propagation velocity that the linear steady propagation is prohibited. In this range, it is revealed that some interesting nonlinear solutions exist. The periodic wavetrain is found to exist as the exact solution. Asymptotic analysis is then made by applying the method of multiple scales and the stationary nonlinear Schrödinger equation is derived for a complex amplitude. A monochromatic solution to this equation corresponds to the exact periodic solution. Imposing undisturbed boundary conditions at infinity, it is revealed that the localized solution exists as a result of balance between the linear instability and the nonlinearity. This solution is checked by solving the nonlinear equation numerically. It is further revealed that the amplitude-modulated wavetrain exists not only in the range of the velocity mentioned above but also outside of it. 相似文献
6.
Hiroaki Minamisawa Ryoko Okunugi Mayumi Minamisawa Satoshi Tanaka Kazunori Saitoh Nobumasa Arai Masami Shibukawa 《Analytical sciences》2006,22(5):709-713
The solid-phase extraction (SPE) method for the preconcentration of trace amounts of cadmium using synthetic zeolite A-4 and its determination by graphite furnace atomic absorption spectrometry (GFAAS) was investigated. The preconcentration conditions, such as the optimum pH range of the sample solution for the adsorption of cadmium and the kind of acid solution for dissolving the cadmium-adsorbed synthetic zeolite A-4, as well as the measurement conditions for the determination of cadmium by GFAAS, e.g., the ashing and atomizing temperature, were investigated. Quantitative recovery of cadmium onto zeolite A-4 from the sample solution over the pH range 2.0 - 9.0 was achieved by the batch method. After the solid-phase (cadmium-adsorbed zeolite A-4) was separated from the sample solution by a membrane filter, it was dissolved in 2.0 cm(3) of 2.0 mol dm(-3) nitric acid. An aliquot of the resulting solution was injected into the graphite furnace. In GFAAS measurements an alternate gas (Ar, 90%; O(2), 10%) was used as a sheath gas, and the ashing temperature and atomizing temperature were 400 degrees C and 1600 degrees C, respectively. The detection limit (3 sigma) for cadmium was 0.002 microg dm(-3). The relative standard deviation at 0.010 microg dm(-3) was 3.5 - 4.5% (n = 5). The proposed method has been successfully applied to the analysis of trace cadmium in environmental water samples. 相似文献
7.
H. Nobumasa K. Shimizu M. Nishina T. Kawai 《Zeitschrift für Physik B Condensed Matter》1993,90(4):387-392
Roles of the blocking layer that we named the layer which separates Cu–O2 layers more than 6Å have been studied by comparing two kinds of highT
c
copperoxide superconductors such as Bi(2212) and La(2126) compound. These following results have been obtained. The hole concentration decreases when Sr is substituted by La and increases when Bi is substituted by Pb in Bi(2212), and it can be optimized by these substitution. In La(2126)T
c
becomes up to 43K and the hole concentration (p;[Cu–O]+p) increases to 0.09 by the substitution of Ca for La and heat treatment under high oxygen partial pressure. The distance between Cu–O2 layers in both Bi(2212) and La(2126) are not changed by these substitution and heat treatment. We have found that the blocking layer has not direct roles for the maximumT
c
value of the material though by supplying carriers to Cu–O2 layers, it affects the actualT
c
value. 相似文献
8.
According to the principles proposed for the design of possible new superconductors, we have synthesized two kinds of copper oxides which consist of Pb based layers and fluorite Ln2O2 layers as blocking layers. One consists of SrO/PbO–Cu–PbO/SrO and Ln2O2 as blocking layers inserted by Cu–O2 sheets. The other consists of SrO/(Pb, Cu)O/SrO and Ln2O2 as blocking layers inserted by Cu–O2 sheets. These copper oxides have common characteristics for the candidates of a high temperature superconductor. 相似文献
9.
Nobumasa Chaki Dr. Satoru Muramatsu Yuji Iida Seiya Kenjo Prof. Dr. Yoshiya Inokuchi Prof. Dr. Toshifumi Iimori Prof. Dr. Takayuki Ebata 《Chemphyschem》2019,20(8):996-1000
The S1 electronic state of 7,7,8,8-Tetracyanoquinodimethane (TCNQ) has been investigated by laser induced fluorescence (LIF), dispersed fluorescence (DF) spectroscopy, and lifetime measurements under jet-cooled conditions in the gas-phase. The LIF spectrum showed a weak origin band at 412.13 nm (24262 cm−1) with prominent progression and combination bands involving vibrations of 327, 1098, and 2430 cm−1. In addition, very strong bands appeared at ∼363.6 nm (3300 cm−1 above the origin). Both the LIF and DF spectra indicate considerable geometric change in the S1 state. The fluorescence lifetime of S1 at zero-point level was obtained to be 220 ns. This lifetime is 40 times longer than the radiative lifetime estimated from the S1−S0 oscillator strength. Furthermore, the lifetimes of the vibronic bands exhibited drastic energy dependence, indicating a strong mixing with the triplet (T1) or intramolecular charge-transfer (CT) state. This study is thought to disclose intrinsic nature of TCNQ, which has been well known as a component of organic semiconductors and a versatile p-type dopant. 相似文献
10.
Sterically bulky pyrazines have been successfully utilized for the preparation of discrete oligo-nuclear TBP (trigonal bipyramidal), SqP (square pyramidal), and Oh (octahedral) copper(II) complexes. We have synthesized a unique linear pentanuclear complex [{Cu(hfac)2}5(μ-2-butyl-3-methylpyrazine)4]. The two terminal copper(II) ions have a SqP structure while the three inner ions have an Oh one. The solvent molecule was incorporated in the clearance of the lattice. From another reaction under harsh conditions, we separated [{Cu(hfac)2}3(μ-2-butyl-3-methylpyrazine)2], which can be regarded as the central moiety of the pentanuclear one. We also prepared a dinuclear complex [{Cu(hfac)2}2(μ-tetramethylpyrazine)], in which the pyrazine nitrogen atoms were located at TBP equatorial positions. Single-crystal EPR measurements supported its compressed TBP structure. The exchange coupling was antiferromagnetic with JTBP–TBP/kB = −3.6 K. The linear trinuclear [{Cu(hfac)2}3(μ-2,3,5-trimethylpyrazine)2], having two TBP Cu ions with an intervening Oh Cu ion, showed very weak antiferromagnetic coupling. DFT calculations on these compounds indicated that the σ-type orbital overlap between the Cu and N atoms is essential for superexchange interactions. 相似文献