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51.
Tetsuo Mori Yutaka Kuchihara Ryuichi Tanaka Takehide Tanaka 《Journal of Polymer Science.Polymer Physics》1974,12(3):501-513
Heterogeneous network polymers composed of rigid polypeptide chains and flexible polyether chains were synthesized. That is, poly(L -glutamic acid) (PLGA) was crosslinked with poly(oxyethylene glycol) (PEG) at various carboxy/hydroxyl mole ratios K. The solubility tests and hydrolysis of heterogeneous network polymers suggest that the crosslinking reaction proceeds by esterification. The dynamic mechanical properties of these polymers(100 Hz, ?100–200°C) are greatly influenced by the presence of a trace of water and the weight per cent of PLGA. In addition, some of these polymers show only one maximum in the temperature dispersion of dynamic loss modulus E″ and tan δ, although their shape is rather broad. The x-ray photographs of these polymers show an amorphous halo or weak Debye-Sherrer rings. These findings suggest that these polymers are not simple adducts; neverthless PLGA and/or PEG domains exist. 相似文献
52.
53.
Yamada K Wada N Onaka H Matsubara R Isobe R Inagaki M Higuchi R 《Chemical & pharmaceutical bulletin》2005,53(7):788-791
An ante-iso type regio-isomer on the long chain base moiety of a glucocerebroside, HLC-2-A, has been isolated from its parent glucocerebroside molecular species HLC-2 composed of iso and ante-iso isomers, from the less polar lipid fraction of a chloroform/methanol extract of the sea cucumber Holothuria leucospilota. Reverse-phase HPLC that included a recycling system was effective in separating the regio-isomer from its counterpart, revealing a very close resemblance in structure. Other typical glucocerebroside molecular species HLC-1 and HLC-3 were obtained together with HLC-2. The structures of these glucocerebrosides were determined on the basis of chemical and spectroscopic evidence. 相似文献
54.
Tetrathiafulvalen (TTF) and tetraselenafulvalen (TSF) salts with diorganochloro-stannate anions, [TTF][SnEt2Cl3] (1), [TTF]2[SnPh2Cl4] (2), [TTF]3[SnEt2Cl4] (3), [TTF]3.3[SnPh2Cl4] (4), [TSF]2[SnPh2Cl4] (5) and [TSF]3.3[SnPh2Cl4] (6), were prepared by the reactions of [TTF or TSF]3[BF4]2 with SnR2Cl2 (R = Et or Ph) in the presence of [Ph3PCH2Ph]Cl and by electrocrystallization of TTF or TSF in acetonitrile containing SnR2Cl2 and [Ph3PCH2Ph]Cl. All the salts behave as semiconductors with electrical resistivities of the order of 10–108 Ω cm as compacted samples at 25°C. Electronic reflectance spectra of the simple salts 1, 2 and 5, show a band due to the dimeric(TTF+)2 or (TSF+)2 unit in the 12,200–12,800-cm?1 region. The complex salt 3 exhibits a TTF+/TTF° charge-transfer (CT) band at 8700 cm?1, and the remaining complex salts, 4 and 6, both display CT bands between the radical cations and between the radical cation and the neutral donor molecule. The crystal structure of 3 was determined by a single-crystal X-ray diffraction. The tetragonal crystal, space group I4cm, has cell dimensions a = 11.710(3) Å, c = 25.242(7) Å, and Z = 4. The structure was solved by the heavy-atom method and refined to a final R value of 0.082 for 479 independent reflections with >F° > 3σ(F). TTF molecules exist as trimers, in which a slight lateral shift from the eclipsed TTF overlap occurs, although TTF molecules are arranged with equal spacing between them. The trimer units are located perpendicularly to each other, forming a two-dimensional layer. The [SnEt2Cl4]2? anion is disordered with respect to the two SnEt and two SnCl bonds. 相似文献
55.
56.
Shin'ichi Ishimaru Hitomi Sawatari Ryuichi Ikeda 《Molecular Crystals and Liquid Crystals》2013,570(2):309-314
Abstract Adsorption and electronic properties in tetramethylbenzidine-intercalated tetrasilicicfluormica were investigated by powder X-ray diffraction, ESR, TG, and DC-electric conductivity measurements. 相似文献
57.
YASUYUKI KIMURA ATSUSHI DOI MASATOSHI MISONO SHUNJI KASAHARA HAJIME KATÔ MASAAKI BABA 《Molecular physics》2013,111(8):1161-1170
A single-mode autoscan laser spectrometer operating in the ultraviolet in combination with a collimated molecular beam was used to measure high resolution fluorescence excitation spectra of the CS2 V 1B2 ← X 1Σ+ g transition under collision-free conditions, and the effects of a magnetic field were measured. Rotational and vibrational levels were fully resolved, and Zeeman splittings were observed in many of the perturbed lines. The Zeeman interaction was observed to induce new perturbation, which induces new transitions, level splitting, and energy shift. When the magnetic field strength was changed, the magnitude of the interaction, which was observed in the absence of a magnetic field, changed dramatically depending on the energy shifts of the Zeeman components. It is shown that the V 1B2(1Δu) state is mixed with the B2(3A2) component by first-order spin-orbit interaction, and through the mixed component, the Zeeman interaction between the V 1B2(1Δu) and 3A2(3Δu) states is induced. Large Zeeman splittings were observed for most of the background lines of weak intensity, and this demonstrates that the background levels are levels of the 3A2(3Δu) state. The fluorescence decays of single Zeeman components were observed to be single exponential. The lifetimes of the perturbing 3A2(3Δu) levels were determined by deperturbation analysis. Triplet-triplet 3A2(3Δu) → 3B2(3Σ+ u) emission was confirmed. It was demonstrated that the quenching of the V 1B2 → X 1Σ+ g fluorescence by a magnetic field was caused by mixing of the 3A2 state with the V 1B2 state and the resulting increase of triplet-triplet emission. In a time-dependent picture, the intersystem crossing from the 1B2(1Δu) and 3A2(3Δu) states is enhanced by the magnetic field. 相似文献
58.
A review of system identification based on distribution theory is given. By the Schwartz kernel theorem, to every continuous linear system there corresponds a unique distribution, called kernel distribution. Formulae using wavelet transform to access time--frequency information of kernel distributions are deduced. A new wavelet-based system identification method for health monitoring systems is proposed as an application of a discretized formula using stationary wavelet transform. 相似文献
59.
Ryuichi Ashino Carlos A. Berenstein Akira Morimoto Mitsuo Morimoto Domenico Napoletani 《Applicable analysis》2013,92(5):577-609
The blind source separation problem is discussed in this article. Focusing on the assumption of independency of the sources in the time-frequency domain, we present a mathematical formulation for the estimation problem of the number of sources. The proposed method uses the quotient of complex valued time-frequency information of only two observed signals to detect the number of sources. No fewer number of observed signals than the detected number of sources is needed to separate sources. The assumption on sources is quite general independence in the time-frequency plane, which is different from that of independent component analysis. We propose algorithms with feedback and give numerical simulations to show the method works well even for noisy case. 相似文献
60.
Free-vibration acoustic resonance of a one-dimensional nonlinear elastic bar was investigated by direct analysis in the calculus of variations. The Lagrangian density of the bar includes a cubic term of the deformation gradient, which is responsible for both geometric and constitutive nonlinearities. By expanding the deformation function into a complex Fourier series, we derived the action integral in an analytic form and evaluated its stationary conditions numerically with the Ritz method for the first three resonant vibration modes. This revealed that the bar shows the following prominent nonlinear features: (i) amplitude dependence of the resonance frequency; (ii) symmetry breaking in the vibration pattern; and (iii) excitation of the high-frequency mode around nodal-like points. Stability of the resonant vibrations was also addressed in terms of a convex condition on the strain energy density. 相似文献