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981.
Takayuki Nakano Tomonari Shioda Naomi Enomoto Eiji Abe Masakazu Sugiyama Yoshiaki Nakano Yukihiro Shimogaki 《Journal of Crystal Growth》2012,347(1):25-30
Fabrication of abrupt InGaP on GaAs (InGaP/GaAs) and GaAs on InGaP (GaAs/InGaP) hetero-interfaces has been difficult using metal organic vapor phase epitaxy (MOVPE) due to the exchange of P and As during the fabrication steps. Indium (In) surface segregation during InGaP growth also degrades the abruptness. Here, the MOVPE gas-switching sequence to fabricate atomically abrupt hetero-interfaces was optimized and the effects of this optimization on the hetero-interface abruptness were quantitatively evaluated using the Z-contrast method with scanning transmission electron microscopy (STEM). Results revealed that (a) in the fabrication of InGaP/GaAs hetero-interface, the GaAs top layer should be stabilized using As-source gas supply, and the excess As layer on GaAs should be terminated using an additional supply of Ga species, and (b) in the fabrication of GaAs/InGaP interface, the InGaP layer should be grown using the flow modulation method to suppress In surface segregation. In conclusion, the abruptness of hetero-interfaces of InGaP/GaAs and GaAs/InGaP was improved by using these optimized gas-switching sequences. 相似文献
982.
Abe K Fuke H Haino S Hams T Hasegawa M Horikoshi A Kim KC Kusumoto A Lee MH Makida Y Matsuda S Matsukawa Y Mitchell JW Nishimura J Nozaki M Orito R Ormes JF Sakai K Sasaki M Seo ES Shinoda R Streitmatter RE Suzuki J Tanaka K Thakur N Yamagami T Yamamoto A Yoshida T Yoshimura K 《Physical review letters》2012,108(5):051102
The energy spectrum of cosmic-ray antiprotons (p's) from 0.17 to 3.5 GeV has been measured using 7886 p's detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary p calculations. Cosmologically primary p's have been investigated by comparing measured and calculated p spectra. BESS-Polar II data show no evidence of primary p's from the evaporation of primordial black holes. 相似文献
983.
Abe K Fuke H Haino S Hams T Hasegawa M Horikoshi A Itazaki A Kim KC Kumazawa T Kusumoto A Lee MH Makida Y Matsuda S Matsukawa Y Matsumoto K Mitchell JW Myers Z Nishimura J Nozaki M Orito R Ormes JF Sakai K Sasaki M Seo ES Shikaze Y Shinoda R Streitmatter RE Suzuki J Takasugi Y Takeuchi K Tanaka K Thakur N Yamagami T Yamamoto A Yoshida T Yoshimura K 《Physical review letters》2012,108(13):131301
In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4×10(6) |Z|=2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4.0×10(7) |Z|=2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9×10(-8)} was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0×10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date. 相似文献
984.
Photoelectrochemical measurements were used to study the photoelectrode characteristics of composite nanoparticles composed of fullerene C60 and partially hydrolyzed aluminum phthalocyanine chloride (AlPc). In cyclic voltammetry measurements, the electrodes coated with the composite nanoparticles were found to have photoanodic [electron donor: 2-mercaptoethanol (ME)] and photocathodic (electron acceptor: O2) characteristics similar to those of the vapor-deposited p/n junction electrode. Their photoanodic features were further investigated with respect to the transient photocurrent response to light irradiation and the dependence on ME concentration (under potentiostatic conditions), from which it was noted that there was a decrease in the initial spiky photocathodic current and saturation of the steady-state photoanodic current at a higher ME concentration. Thus, the reaction kinetics was probably dominated by charge transport process. Moreover, external and internal quantum efficiency spectrum measurements indicated that the composite nanoparticles responded to the full spectrum of visible light ( < 880 nm) for both the photoanodic and photocathodic current. The present research will assist comprehension of photocatalytic behavior of the composite nanoparticles. 相似文献
985.
986.
Nakamura T Koyama E Shimoi Y Abe S Ishida T Tsukagoshi K Mizutani W Tokuhisa H Kanesato M Nakai I Kondoh H Ohta T 《The journal of physical chemistry. B》2006,110(18):9195-9203
Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2'-bipyridine-5'-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method. 相似文献
987.
Toshiaki Abe Munenori Inoue Takeyuki Suzuki Tadashi Katoh 《Tetrahedron letters》2006,47(19):3251-3255
The first total synthesis of (−)-nalanthalide (1), a novel blocker of the voltage-gated potassium channel Kv1.3 from a microorganism, was accomplished in a convergent manner by utilizing coupling reaction of the trans-decalin 5 with 3-lithio-γ-pyrone 4. The key intermediate 5 was efficiently prepared from the known trans-decalone 7 through a [2,3]-Wittig rearrangement of the stannylmethyl ether 6 to install the stereogenic center at C9 and the exo-methylene function at C8. 相似文献
988.
Kiyoshi Sato Yuu Katayama Takamichi Yamagishi Sadao Arai 《Journal of heterocyclic chemistry》2006,43(1):177-181
989.
Yoshida N Abe Y Shigeta H Nakajima A Ohsaki H Hashimoto K Watanabe T 《Journal of the American Chemical Society》2006,128(3):743-747
Flat films of methyl methacrylate-fluoroalkyl methacrylate copolymers were prepared, and their hydrophobicity was investigated. It was revealed that the F concentration directly affects the static hydrophobicity on the flat polymer surface in a systematic manner. Furthermore, the sliding behavior of a water droplet on these surfaces depends on the static hydrophobicity; the sliding motion changes from constant velocity to constant acceleration with an increase in the water contact angle. 相似文献
990.
Hashizaki K Taguchi H Tsuchiya K Sakai H Abe M Saito Y Ogawa N 《Chemical & pharmaceutical bulletin》2006,54(4):561-563
The phase behavior of poly(ethylene glycol) grafted liposomes (PEG-liposomes) was investigated by differential scanning calorimetry (DSC), dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM). PEG-liposomes were prepared from mixtures of dipalmitoyl phosphatidylcholine (DPPC) and distearoyl phosphatidylethanolamine with a covalently attached PEG molecular weight of 2000 (DSPE-PEG2000). From the results of DLS measurements, the coexistence of PEG-liposomes and small molecular assemblies were confirmed at mole fractions of DSPE-PEG2000 above about 0.1. Moreover, it was confirmed that small molecular assemblies were disk micelles by cryo-TEM. However, the phase transition enthalpies of PEG-liposomes were hardly changed according to the DSC measurement, though the mole fraction of the PEG lipid increased. From these results, it was suggested that the phase transition enthalpies hardly changed despite mixed micelles being formed because the bilayer structure of the disk micelle maintains high cooperativity between the DPPC molecules. 相似文献