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71.
A new compound of sodium nonatitanate, Na2Ti9O19, has been prepared by the hydrothermal reactions of titanium dioxide gel with sodium hydroxide aqueous solution. The crystal has a C-centered monoclinic lattice with the unit-cell dimensions a = 12.2, b = 3.78, c = 15.3Å, and β = 98.0°. It is expected that the structure consists of a framework different from those in tri-, hexa-, hepta-, and octatianates. 相似文献
72.
Vibrational spectra reveal that ice VII′ transforms to low-density amorphous ice (LDA) at low temperature on release of pressure to ambient pressure and low temperature. The measurements were obtained using in situ Raman spectroscopy of samples of ice VII′ as a function of pressure at 135 K. The observation of this direct decompression-induced VII′-LDA transition complements the previously observed pressure-induced reversible transition between LDA and high-density amorphous ice (HDA) at 120–140 K and the temperature-induced amorphization of metastable ice VII and ice VIII at 0.1 MPa. 相似文献
73.
Tachi T Hase T Okamoto Y Kaji N Arima T Matsumoto H Kondo M Tokeshi M Hasegawa Y Baba Y 《Analytical and bioanalytical chemistry》2011,401(7):2301-2305
Microchip analysis is a promising method for therapeutic drug monitoring. This led us to evaluate a microchip-based fluorescence
polarization immunoassay (FPIA) system for point-of-care testing on patients being treated with theophylline. The sera were
collected from 20 patients being treated with theophylline. Fluorescence polarization was measured on the microchip and theophylline
concentrations in serum were obtained. Regression analysis of the correlations was done between the results given by the microchip-based
FPIA and the conventional cloned enzyme donor immunoassay (CEDIA), and between the results given by the microchip-based FPIA
and the conventional particle-enhanced turbidimetric inhibition immunoassay (PETINIA). We successfully carried out a quantitative
analysis of theophylline in serum at values near its therapeutic range in 65 s. The results obtained by the microchip-based
FPIA correlated well with CEDIA and PETINIA results; the correlation coefficients (R
2) were 0.986 and 0.989, respectively. The FPIA system is a simple and rapid method for point-of-care testing of drugs in serum,
and its accuracy is the same as the conventional CEDIA and PETINIA. It is essential to use real samples from patients and
to confirm good correlations with conventional methods for a study on the realization of microchip. 相似文献
74.
Fumiaki Ishii Toshio Ohga Akihiro Tsutsumi Hiroji Ohigashi 《Journal of Polymer Science.Polymer Physics》2002,40(10):1026-1037
The heterogeneous higher order structure and molecular motion in a single crystalline film of a vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer with 73 mol % VDF was investigated with the 1H–13C cross‐polarization/magic‐angle spinning NMR technique. A transient oscillation was observed in plots of the 13C peak intensity versus the contact time for the CH2, CHF, and CF2 groups. On the basis of the extended cross‐relaxation theory of spin diffusion, we determined that the oscillation behavior was caused by the TrFE‐rich segments in the chain and that the crystal consisted of VDF‐rich and TrFE‐rich domains. The former had TrFE‐rich segments in VDF and TrFE fractions of 0.24 and 0.27, respectively, and the latter had VDF‐rich segments in a VDF fraction of 0.49. The spin–lattice relaxation time T1ρH in the rotating frame for each group was minimal in the three temperature regions of β, αb, and αc (↑) on heating and in the two temperature regions of α1D and αc (↓) on cooling. The αc (↑) and αc (↓) processes depended on the first‐order ferroelectric phase‐transition regions on heating and cooling, respectively. The motional modes for the other processes were confirmed by the T1ρH minimum behavior of the VDF and TrFE groups in the TrFE‐rich domain and the VDF‐rich segments in the VDF‐rich domain. The β and αb processes were attributed to the flip–flop motion of the TrFE‐rich segments and the competitive motion of the TrFE‐ and VDF‐rich segments in the ferroelectric phase, respectively. The α1D process was due to the one‐dimensional diffusion motion of the conformational defects along the chain in the paraelectric phase, accompanied by the trans and gauche transformation of the VDF conformers of ttg+tg? and g+tg?tt. The effect of the competitive motion of the TrFE‐rich segment on the thermal stability of the VDF‐rich segment in the chain near the Curie temperature was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1026–1037, 2002 相似文献
75.
We construct a supersymmetric left–right model in four dimension with gauge-Higgs unification starting from a SU(3)c×SU(4)w×U(1)B−L gauge symmetry in five dimension. The model has several interesting features, such as, the CKM mixings in the quark sector are naturally small while for the neutrino sector it is not, light neutrino masses can be generated via the seesaw mechanism in the usual way, and the model has a U(1)R symmetry which naturally forbid dimension five proton decay operators. We also discuss the grand unification of our model in SO(12) in five dimensions. 相似文献
76.
77.
Yukihiro Nishikawa 《Studies in Applied Mathematics》2007,119(1):1-71
We develop the exact WKB analysis of the P II hierarchy introduced by Gordoa et al. [ 5 ] in this paper; our particular interest is in the relation between the Stokes geometry of a higher order Painlevé equation in the hierarchy and that of its underlying Lax pair. An important observation is that Stokes curves of the Painlevé equation may cross, reflecting the higher order character of the equation, and in a neighborhood of the crossing point an unexpected degeneracy of the Stokes geometry of the Lax pair may occur along a curved ray emanating from the crossing point. 相似文献
78.
Hitoshi Shimasaki Makoto Tsutsumi 《International Journal of Infrared and Millimeter Waves》1989,10(9):1131-1138
Conclusions We have analyzed coupling properties of the coupled microstrip lines whose substrate contain electron-hole plasma by means of the spectral domain method. Scattering parameters in each ports have been evaluated numerically as a function of plasma density.Experiments were carried out using high resistivity silicon and LEDs. The agreement of the theoretical and experimental results was satisfactory. The plasma density observed in the experiments is one-third as large as the theoretically estimated value. 相似文献
79.
Tsuyoshi Kiyotsukuri Naoto Tsutsumi Ying-Hsien Chen 《Journal of polymer science. Part A, Polymer chemistry》1990,28(5):1197-1208
Novel regular network polyester films were prepared from benzenetricarboxylic acids of trimesic (Y) and trimellitic (Z) acids, and glycols of ethylene (2G), tetramethylene (4G), and hexamethylene (6G) glycols. Prepolymers prepared by melt polycondensation for a short period within 1 h were cast from a DMF solution and successively post-polymerized at various temperatures and times to form a network. The resultant films were transparent, flexible, and insoluble in any solvents. Distortion temperature measured by a penetration mode of thermomechanical analysis (TMA) increased with increasing post polymerization time and temperature, and leveled out at 222, 168, 125 and 75°C, for the 2GY, 2GZ, 4GY, and 6GY films, respectively. Temperatures close to 400°C at which the probe had completely penetrated corresponded to the thermal decomposition temperature of these films. Two broad but strong peaks in the x-ray diffraction curves appears for the 2GY, 4GY, and 6GY, suggesting the formation of some ordered supramolecular structure owing to the regular network formed by symmetrical trimesic acid moiety, and the intensity of diffraction peaks became higher with increasing length of the methylene chain of the glycol monomer. Densities of the 2GY and 2GZ films decreased with increasing post-polymerization time and temperature. Tensile strength and Young's modulus increased and elongation decreased with increasing network formation. These tensile properties was affected by the chemical structure of the network films. 相似文献
80.
Naoki Yoneda Yukihiro Fukata Dr. Keisuke Asano Prof. Dr. Seijiro Matsubara 《Angewandte Chemie (International ed. in English)》2015,54(51):15497-15500
Chiral spiroketal skeletons are found as core structures in a range of bioactive compounds. These natural compounds and their analogues have attracted much attention in the field of drug discovery. However, methods for their enantioselective construction are limited, and easily available optically active spiroketals are rare. We demonstrate a novel catalytic asymmetric synthesis of spiroketal compounds that proceeds through an intramolecular hemiacetalization/oxy‐Michael addition cascade mediated by a bifunctional aminothiourea catalyst. This results in spiroketal structures through the relay formation of contiguous oxacycles, in which multipoint recognition by the catalyst through hydrogen bonding imparts high enantioselectivity. This method offers facile access to spiroketal frameworks bearing an alkyl group at the 2‐position, which are prevalent in insect pheromones. Optically active (2S,5S)‐chalcogran, a pheromone of the six‐spined spruce bark beetle, and an azide derivative could be readily synthesized from the bicyclic reaction product. 相似文献