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71.
A new configuration is proposed for continuously transforming aspect ratios of field-intensity distributions in optical fibers. The field aspect ratio varies in proportion to the angle between the principal axes of two cascaded graded-index oval-core fibers. The highest aspect-ratio conversion is obtained at an angle of 90 degrees. The conversion effect is numerically and experimentally confirmed, showing that a circular field is successfully transformed into an elliptical one with an aspect ratio as high as 9 at a wavelength of 0.98 microm. 相似文献
72.
Yoshiumi Kohno Eriko Haga Keiko Yoda Masashi Shibata Choji Fukuhara Yasumasa Tomita Yasuhisa Maeda Kenkichiro Kobayashi 《Journal of Physics and Chemistry of Solids》2014
Because of its non-toxicity, naturally occurring anthocyanin is potentially suitable as a colorant for foods and cosmetics. To the wider use of the anthocyanin, the immobilization on the inorganic host for an easy handling as well as the improvement of the stability is required. This study is focused on the adsorption of significant amount of the natural anthocyanin dye onto mesoporous silica, and on the stability enhancement of the anthocyanin by the complexation. The anthocyanin has successfully been adsorbed on the HMS type mesoporous silica containing small amount of aluminum. The amount of the adsorbed anthocyanin has been increased by modifying the pore wall with n-propyl group to make the silica surface hydrophobic. The light fastness of the adsorbed anthocyanin has been improved by making the composite with the HMS samples containing aluminum, although the degree of the improvement is not so large. It has been proposed that incorporation of the anthocyanin molecule deep inside the mesopore is required for the further enhancement of the stability. 相似文献
73.
74.
Satoshi Tsutsui Susumu Shimomura Yoshitaka Yoda Hisao Kobayashi Hideya Onodera 《Hyperfine Interactions》2014,226(1-3):637-642
149Sm nuclear resonant inelastic scattering was carried out in a charge density wave compound SmNiC2. We have investigated temperature dependences of the Sm partial phonon density of states and recoil-free fraction at the Sm site and the average sound velocity estimated from the Sm partial density of states. The Sm partial density of states exhibits temperature dependence, suggesting that the phonon modes between 20 and 25 meV may correlate with the charge density wave. Temperature dependence of the recoil-free fraction is difficult to prove the correlation with either the charge density wave or ferromagnetic ordering. The average sound velocity obtained by the Sm partial phonon density of states exhibits temperature dependence, agreeing qualitatively with very recent elastic constant measurements. 相似文献
75.
The wall ζ‐potential ζw, the potential at the shear plane of the electric double layer, depends on the properties of the BGE solution such as the valence and type of electrolyte, the pH and the ionic strength. Most of the methods estimate ζw from measurements of the EOF velocity magnitude ueo, usually spatially averaged over the entire capillary. In these initial studies, evanescent‐wave particle velocimetry was used to measure ueo in steady EOF for a variety of monovalent aqueous solutions to evaluate the effect of small amounts of divalent cations, as well as the pH and ionic strength of BGE solutions. In brief, the magnitude of the EOF velocity of NaCl‐NaOH and borate buffer‐NaOH solutions was estimated from the measured velocities of radius α = 104 nm fluorescent polystyrene particles in 33 μm fused‐silica microchannels. The particle ζ‐potentials were measured separately using laser‐Doppler micro‐electrophoresis; ζw was then determined from ueo. The results suggest that evanescent‐wave particle velocimetry can be used to estimate ζw for a variety of BGE solutions, and that it can be used in the future to estimate local wall ζ‐potential, and hence spatial variations in ζw. 相似文献
76.
Aikawa K Hioki Y Shimizu N Mikami K 《Journal of the American Chemical Society》2011,133(50):20092-20095
A highly enantioselective and atom-economical [2 + 2] cycloaddition of various alkynes with trifluoropyruvate using a dicationic (S)-BINAP-Pd catalyst has been established. This is the first enantioselective synthesis of stable oxetene derivatives, whose structure has been clarified by X-ray analysis. This catalytic process offers a practical synthetic method for oxetene derivatives (catalyst loading: up to 0.1 mol %), which can serve as novel chiral building blocks for pharmaceuticals and agrochemicals and can also be transformed into a variety of enantiomerically enriched CF(3)-substituted compounds with high stereoselectivity. 相似文献
77.
Natsumi Nitta Mei Takatsuka Shin‐ichi Kihara Takehiro Hirao Takeharu Haino 《Angewandte Chemie (International ed. in English)》2020,59(38):16690-16697
The repeating guest units of poly‐(R)‐ 2 were selectively encapsulated by the self‐assembled capsule poly‐ 1 possessing eight polymer side chains to form the supramolecular graft polymer (poly‐ 1 )n?poly‐(R)‐ 2 . The encapsulation of the guest units was confirmed by 1H NMR spectroscopy and the DOSY technique. The hydrodynamic radius of the graft polymer structure was greatly increased upon the complexation of poly‐ 1 . The supramolecular graft polymer (poly‐ 1 )n?poly‐(R)‐ 2 was stably formed in the 1:1 host–guest ratio, which increased the glass transition temperature by more than 10 °C compared to that of poly‐ 1 . AFM visualized that (poly‐ 1 )n?poly‐(R)‐ 2 formed the networked structure on mica. The (poly‐ 1 )n?poly‐(R)‐ 2 gelled in 1,1,2,2‐tetrachloroethane, which led to fabrication of distinct viscoelastic materials that demonstrated self‐healing behavior in a tensile test. 相似文献
78.
S. Kikuta Y. Yoda Y. Hasegawa K. Izumi T. Ishikawa X. W. Zhang S. Kishimoto H. Sugiyama T. Matsushita M. Ando C. K. Suzuki M. Seto H. Ohno H. Takei 《Hyperfine Interactions》1992,71(1-4):1491-1494
Experiments of nuclear Resonant scattering carried out at PF and TRISTAN-AR of KEK are described, which include nuclear Bragg
scattering in time domain as well as energy domain, time-resolved nuclear resonant forward scattering, and interferometric
studies. 相似文献
79.
80.
George SJ Igarashi RY Xiao Y Hernandez JA Demuez M Zhao D Yoda Y Ludden PW Rubio LM Cramer SP 《Journal of the American Chemical Society》2008,130(17):5673-5680
NifB-co, an Fe-S cluster produced by the enzyme NifB, is an intermediate on the biosynthetic pathway to the iron molybdenum cofactor (FeMo-co) of nitrogenase. We have used Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy together with (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to probe the structure of NifB-co while bound to the NifX protein from Azotobacter vinelandii. The spectra have been interpreted in part by comparison with data for the completed FeMo-co attached to the NafY carrier protein: the NafY:FeMo-co complex. EXAFS analysis of the NifX:NifB-co complex yields an average Fe-S distance of 2.26 A and average Fe-Fe distances of 2.66 and 3.74 A. Search profile analyses reveal the presence of a single Fe-X (X = C, N, or O) interaction at 2.04 A, compared to a 2.00 A Fe-X interaction found in the NafY:FeMo-co EXAFS. This suggests that the interstitial light atom (X) proposed to be present in FeMo-co has already inserted at the NifB-co stage of biosynthesis. The NRVS exhibits strong bands from Fe-S stretching modes peaking around 270, 315, 385, and 408 cm(-1). Additional intensity at approximately 185-200 cm(-1) is interpreted as a set of cluster "breathing" modes similar to those seen for the FeMo-cofactor. The strength and location of these modes also suggest that the FeMo-co interstitial light atom seen in the crystal structure is already in place in NifB-co. Both the EXAFS and NRVS data for NifX:NifB-co are best simulated using a Fe 6S 9X trigonal prism structure analogous to the 6Fe core of FeMo-co, although a 7Fe structure made by capping one trigonal 3S terminus with Fe cannot be ruled out. The results are consistent with the conclusion that the interstitial light atom is already present at an early stage in FeMo-co biosynthesis prior to the incorporation of Mo and R-homocitrate. 相似文献