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651.
We studied the crystallization of CaCO3 by the photoisomerization of azobenzene groups in poly[1-[4-[3-carboxy-4-hydroxyphenylazobenzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO) in a mixture of dimethyl sulfoxide and water at 30 °C. The products were characterized by scanning electron microscopy (SEM), FT-IR, and powder X-ray diffraction (XRD) analysis. We observed that the different shapes of spherical vaterite particles were produced by the changes of configuration and polarity of the azobenzene groups in the polymer which resulted from photo-induced isomerization. The results indicate that the nucleation of primary particles of CaCO3 was inhibited by in situ photo-induced cis–trans isomerization of PAZO. Therefore, we suggest that the shapes of the spherical vaterite can be effectively modified by photoisomerization of the azobenzene groups in the polymer at the initial stage of CaCO3 crystallization. 相似文献
652.
Yoshiki Nakata Keiichi Murakawa Kenji Sonoda Kazuma Momoo Noriaki Miyanaga Takuya Hiromoto 《Applied Physics A: Materials Science & Processing》2013,112(1):191-196
We have studied material processing by using an interfering ultra-short pulse laser. In this process, an interference pattern is transferred to material surface, and a periodic structure can be generated in a single shot of laser irradiation. Here, it is well known that the period of the interference pattern can be controlled by correlation angle and wavelength. In addition, a composite, doubled in density or designed interference pattern can be formed by controlling the phase shift and variation of amplitude between the interfering laser beams. In this paper, basic patterns of interference are summarized in the case of four-beam correlation. 相似文献
653.
Kazuya Takemoto Yoshiki Sakuma Shinichi Hirose Tatsuya Usuki Naoki Yokoyama Toshiyuki Miyazawa Motomu Takatsu Yasuhiko Arakawa 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):185
We present an optical spectroscopy and photon correlation measurement at telecommunication wavelengths performed on single InAs/InP quantum dots. Two main approaches brought high optical quality: an application of a ‘double-cap’ growth method to metalorganic chemical vapor deposition, and fabrication of a small mesa structure using low-damage wet chemical etching. Sharp and discrete exciton transition lines have been observed on the single quantum dots, which widely cover the spectral range of 1.3–1.55 μm. Using a pulsed excitation source and gated single-photon detection modules, we observed a photon antibunching behavior for an isolated exciton emission line, indicating nonclassical light emission near the wavelength of 1.3 μm. 相似文献
654.
[5-Acyl-2-(trimethylsilyl)phenyl]iodonium triflates were prepared for the generation of benzynes bearing ketone function. Treatment of the iodonium triflates with Bu4NF in CH2Cl2 in the presence of furan at room temperature gave 6-acyl-1,4-epoxy-1,4-dihydronaphthalenes in high yields. The mild conditions and the tolerance of the ketone function on benzyne generation are attributable to the advantage of hypervalent iodine compounds. 相似文献
655.
656.
Brendan J. Kennedy Christopher J. Howard Yoshiki Kubota 《Journal of solid state chemistry》2004,177(12):4552-4556
The crystal structure of the layered perovskite La1/3NbO3 has been studied between room temperature and 500 °C using synchrotron X-ray powder diffraction methods. The structure shows ordering of the La cations at all temperatures. At room temperature La1/3NbO3 is orthorhombic with the NbO6 octahedra showing out-of-phase tilting about the a-axis. This tilting diminishes as the temperature increases, so that above 200 °C the structure is tetragonal. The transition to the tetragonal structure is found to be continuous and analysis of the spontaneous strains shows it to be tricritical in nature. 相似文献
657.
Subaqueous deltaic deposits with approximately 30 radiocarbon ages show that the Changjiang River delta was strongly affected by tides and that the delta progradation rate after 2 kaBP was almost double the rate before 2 kaBP. This change in the progradation rate correlates well with the active extension of the subaerial delta plain shown by previous work. Widespread human activities, such as farming, deforestation, and dike construction, probably resulted in an increase in sediment discharge to the river-mouth area. 相似文献
658.
Development of near-infrared-emissive aza-boron dipyrromethene (aza-BODIPY) derivatives having furanyl groups is reported. From the optical measurements, it was clearly indicated that the emission bands were presented in the longer wavelength region than those of the conventional aza-BODIPYs. The emission bands with the peaks at 730 nm and 758 nm were observed from the bis- and tetra-substituted furanyl aza-BODIPYs with similar extents of emission efficiencies, respectively. According to the computer calculations, it was proposed that molecular planarity could be enhanced in the case of the furan groups. As a result, band-gap energy could be lowered comparing to those of the conventional benzene and thiophene-substituted aza-BODIPYs. 相似文献
659.
Yoshihiro Suyama Yusuke Higashino Naonobu Tanaka Yutaka Tatano Hideki Yagi Kazuyoshi Kawazoe Kotaro Murakami Shun-Lin Li Han-Dong Sun Yoshiki Kashiwada 《Tetrahedron letters》2017,58(48):4568-4571
Three new naphthoquinone derivatives, rubiaquinones A–C (1–3), were isolated from the roots of Rubia yunnanensis. Rubiaquinone A (1) was a racemic naphthoquinone dimer consisting of a 1,4-dihydroxynaphthalene and a 4-hydroxy-1,2-naphthoquinone moieties with a 2-oxo-propyl group. Rubiaquinones B (2) and C (3) were structurally unique trimeric naphthoquinones with a racemic nature possessing one chiral axis and one chiral carbon in common. The planar structures of 1–3 were assigned by detailed spectroscopic analyses, and enantiomers of 1–3 were obtained by optical resolutions. The absolute configurations of (+)-1 and (?)-1 were elucidated by interpretation of the ECD spectra with the aid of TDDFT ECD calculation, while those of enantiomers obtained from 2 and 3 were assigned by analyses of the composite ECD spectra generated by summing appropriate ECD spectra of enantiomers. Rubiaquinone A (1) exhibited antimicrobial activity against Bacillus subtilis. 相似文献
660.
In this study, we developed a method to observe interactions between cellulase and cellulose microfibril by transmission electron microscopy. Although negative staining and low-angle metal shadowing increase image contrast, neither method is sufficient to view enzyme interactions with microfibril. However, we found that the combination of negative staining and low-angle metal shadowing provided better contrast for enzyme-like particles on the microfibril. The lengths of the particles interacting with microfibrils were 7.03 and 5.05 nm, parallel and perpendicular to the fiber direction, respectively. Accounting for the additional thickness owing to metal shadowing, the particle sizes were consistent with that of CBH I from Trichoderma reesei based on a crystalline structural analysis. The combination of these electron staining techniques successfully visualized morphological changes in microfibril as well as enzymes adsorbed on it, thus demonstrating cellulase in action. These results indicate that appropriate staining techniques can be applied to extend the applications of transmission electron microscopy, which may be particularly beneficial for studies on enzymatic behavior. 相似文献