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91.
Enrico Bovero Dr. Kazuhisa Yano Dr. Tadashi Nakamura Yuri Yamada Frank C. J. M. van Veggel Prof. Dr. Ir. 《Chemphyschem》2010,11(12):2550-2554
The effects of the stop band (SB) in colloidal photonic crystals composed of silica spheres containing Eu3+‐ and Tb3+‐doped yttria nanoparticles are analysed. Reflection and transmission spectra indicate movement of the stop band, due to the 111 series of planes, towards shorter wavelengths with increasing angle of observation. The profile of the emission spectra is modified by the presence of the SB depending on the angle of measurement. Such a modification is more effective for a narrow emission band and it is thus more evident in the case of Tb3+ than Eu3+. An angular effect is also observed in the lifetime, which presents two maxima and one minimum. In the case of Tb3+ the maxima are at observation angles of 35 and 50°, and the minimum at 45°. We attribute this behaviour to penetration of the excitation beam at 475 nm modulated by the stop band. The ions excited in this way emit from different depths in the crystal, and therefore their lifetime will be affected differently by the same stop band, depending on the thickness of the crystal that must be crossed. Eu3+ shows a similar but less pronounced effect for two reasons: first, the main stop band (due to the 111 planes) is not effective at the excitation wavelength of 392 nm; second, the broadness of the Eu3+ emission is comparable to the width of the SB, and a decrease in the transition rate at the wavelength of the SB maximum is compensated by an increase at the sides of the SB. 相似文献
92.
Toshihiro Kondo Kazuhisa Tamura Satoru Takakusagi Ken Kitamura Masamitu Takahasi Jun’ichiro Mizuki Kohei Uosaki 《Journal of Solid State Electrochemistry》2009,13(7):1141-1145
The interfacial structures of Ag bilayer prepared by underpotential deposition on Au(111) (Ag(2ML)/Au(111)) were determined
by ex situ scanning tunneling microscopy and in situ surface X-ray scattering measurements before and after oxidative adsorption
and after reductive desorption of a self-assembled monolayer (SAM) of hexanethiol (C6SH) in alkaline ethanol solution. While no structural change was observed after oxidative formation of C6SH SAM on the Ag(2ML)/Au(111) in an ethanol solution containing 20 mM KOH and 0.1 mM C6SH, some of the Ag atoms in the bilayer were stripped when the SAM was reductively desorbed.
Dedicated to Professor J. O’M. Bockris on the occasion of his 85th birthday. 相似文献
93.
Yui T Kobayashi Y Yamada Y Tsuchino T Yano K Kajino T Fukushima Y Torimoto T Inoue H Takagi K 《Physical chemistry chemical physics : PCCP》2006,8(39):4585-4590
Photochemical Electron Transfer (ET) between an organic dye, the porphyrin derivative TMPyP, and an electron acceptor, methyl viologen MV2+, have been investigated at the interface of two different inorganic films, i.e., layered titania nano-sheets (TNS) and a monolayer film of spherical and mono-dispersed mesoporous silica (sMPS) particles (ca. 0.5 microm). TMPyP ions were intercalated within the sMPS nano-cavities to form (TMPyP-sMPS) while MV2+ ions were intercalated into the TNS interlayers to form (MV2+-TNS). The (TMPyP-sMPS) and (MV2+-TNS) films were then stacked on a silica substrate in this order to form a (MV2+-TNS)/(TMPyP-sMPS) film and, upon UV light irradiation, ET could be induced. However, when this film was stacked inversely, i.e., for the (TMPyP-sMPS)/(MV2+-TNS) films on a silica substrate, no photoinduced ET were observed. Interestingly, however, even for this photo-inactive inversely stacked film, ET could be generated by inserting a gold vapor-deposited layer between the (MV2+-TNS) and (TMPyP-sMPS) films. The conjugation conditions at the interface of the inversely stacked (TMPyP-sMPS)/(MV2+-TNS) hybrid film were, thus, confirmed to strongly affect the photoinduced electron transfers and their efficiencies. 相似文献
94.
Shigeto Fukushima Megumi Machida Tomoko Akutsu Kazuhisa Shimizu Shigeo Tanaka Kazuya Okamoto Hiroko Mashiba Masayuki Yokoyama Teruo Okano Yasuhisa Sakurai Kazunori Kataoka 《Colloids and surfaces. B, Biointerfaces》1999,16(1-4):227-236
Adriamycin (ADR) dimer was prepared and its antitumor activity was evaluated with mouse colon adenocarcinoma 26 (C 26). As compared with original ADR, the dimer did not show significant antitumor activity, either in vitro or in vivo. Furthermore, polymeric micelles containing varied ratios of the dimer to the original ADR were prepared. Polymeric micelles with a higher dimer/ADR ratio (9.7) showed significant antitumor activity, but the effective dose shifted higher. Effective doses were found to largely depend on the concentration of the original ADR, rather than that of the dimer at the tumor sites. Therefore, it was presumed that the original ADR played a major role in antitumor activity, and the dimer played a supplementary role to contribute selective delivery of ADR to the tumor sites. 相似文献
95.
Junzo Otera Yukari Yoshinaga Kazuhisa Hirakawa Tetsuya Nakata 《Tetrahedron letters》1985,26(27):3219-3222
Organotin phosphate condensates proved to catalyze the ring opening reaction of epoxides with alcohols in a highly regioselective manner. 相似文献
96.
Kazuhisa Hiratani Hirotaka Uzawa Kazuyuki Kasuga Hide Kambayashi 《Tetrahedron letters》1997,38(52):319-8996
A series of crownophanes containing two phenolic moieties within a macrocyclic ring have been successfully synthesized by a one-step thermal reaction from the corresponding macrocyclic polyethers by using a “Tandem Claisen Rearrangement”. 相似文献
97.
1,3-Butadiene-2-carboxylates were treated with a titanium(II) alkoxide reagent, Ti(O-i-Pr)4/2i-PrMgCl, to generate diene-titanium alkoxide complexes, the presence of which was verified by hydrolysis and deuteriolysis to give the corresponding monoolefins or their bis-deuterated counterpart. These diene complexes underwent successive addition to an aldehyde (as the first electrophile) and iodine (as the second one) in a highly regio- and stereoselective manner to give the corresponding iodo alcohol. Optically active 1,3-butadiene-2-carboxylates afforded the same adducts of high asymmetric induction. Besides these electron-deficient dienes, electron-rich 2-siloxy-1,3-butadienes also participated in the formation of the titanium complex, which led to the preparation of functionalized enol silyl ethers through regio- and stereoselective coupling with carbonyl compounds and hydrolytic workup. 相似文献
98.
Shiro Kobayashi Hiroshi Uyama Seog Won Lee Yasuhiro Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》1993,31(12):3133-3139
This article describes the preparation of micron-size monodisperse polymer particles by dispersion copolymerization of styrene with a poly(2-oxazoline) macromonomer in an aqueous ethanol solution. The macromonomer acted as a comonomer as well as a stabilizer. The diameter of the particles increased as the concentration of the macromonomer decreased. The higher the molecular weight of the macromonomer, the smaller the particle size. The copolymerization in the solvent containing higher water content gave smaller polymer particles. Under the condition giving the monodisperse particles, the particles volume increased linearly with the yield of the particles. From ESCA analysis of the particle surface, poly(2-oxazoline) chains were enriched on the surface. © 1993 John Wiley & Sons, Inc. 相似文献
99.
100.
The lipase‐catalyzed regioselective polymerization of divinyl sebacate and triols has been carried out. Immobilized lipase derived from Candida antarctica induces the polymerization of divinyl sebacate and glycerol, yielding a soluble polymer of relatively high molecular weight. NMR analysis showed that 1,3‐diglyceride is a main unit and the branching unit (triglyceride) is contained in the resulting polymer. These data indicate that the polymerization proceeds regioselectively to give the reactive polyester having a pendant hydroxy group. 相似文献