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101.
Ali Khumaeni Masahiko Tani Kazuyoshi Kurihara Kiichiro Kagawa Hideaki Niki 《Analytical letters》2017,50(12):1992-1999
A novel method of laser-induced plasma spectroscopy utilizing a pulsed transversely excited atmospheric CO2 laser has been developed for the high-sensitivity determination of heavy metals in soil. A coarse metal powder was used to trap the soil and to assist with plasma generation. When the CO2 laser (10.6?µm, 1.5?J, 200?ns) was irradiated on the metal and soil powder, a high-temperature and long-lifetime luminous plasma was induced. Fine particles of soil were dissociated and were excited in the plasma region. The method was used for the rapid determination of Cr, Pb, and Hg in loam. The limits of detection for Cr, Pb, and Hg were approximately 0.8, 15, and 0.7?mg/kg, respectively. 相似文献
102.
Taku Hirama Takayuki Umemura Noriyuki Kogure Mariko Kitajima Hiromitsu Takayama 《Tetrahedron letters》2017,58(3):223-226
A new procedure for the asymmetric total synthesis of lythraceous alkaloids with a 4-arylquinolizidine skeleton was developed, which involved an organocatalyzed asymmetric intramolecular aza-Michael addition. 相似文献
103.
Experimental investigation on tunnel sonic boom 总被引:1,自引:0,他引:1
Upon the entrance of a high-speed train into a relatively long train tunnel, compression waves are generated in front of the train. These compression waves subsequently coalesce into a weak shock wave so that a unpleasant sonic boom is emitted from the tunnel exit. In order to investigate the generation of the weak shock wave in train tunnels and the emission of the resulting sonic boom from the train tunnel exit and to search for methods for the reduction of these sonic booms, a 1300 scaled train tunnel simulator was constructed and simulation experiments were carried out using this facility.In the train tunnel simulator, an 18 mm dia. and 200 mm long plastic piston moves along a 40 mm dia. and 25 m long test section with speed ranging from 60 to 100 m/s. The tunnel simulator was tilted 8° to the floor so that the attenuation of the piston speed was not more than 10 % of its entrance speed. Pressure measurements along the tunnel simulator and holographic interferometric optical flow visualization of weak shock waves in the tunnel simulator clearly showed that compression waves, with propagation, coalesced into a weak shock wave. Although, for reduction of the sonic boom in prototype train tunnels, the installation of a hood at the entrance of the tunnels was known to be useful for their suppression, this effect was confirmed in the present experiment and found to be effective particularly for low piston speeds. The installation of a partially perforated wall at the exit of the tunnel simulator was found to smear pressure gradients at the shock. This effect is significant for higher piston speeds. Throughout the series of train tunnel simulator experiments, the combination of both the entrance hood and the perforated wall significantly reduces shock overpressures for piston speeds ofu
p
ranging from 60 to 100 m/s. These experimental findings were then applied to a real train tunnel and good agreement was obtained between the tunnel simulator result and the real tunnel measurements. 相似文献
104.
Kobayashi M Matsuo T Fukunaga T Hashizume D Fueno H Tanaka K Tamao K 《Journal of the American Chemical Society》2010,132(43):15162-15163
π-Conjugated disilenes with 2-naphthyl or 2-fluorenyl groups on the silicon atoms have been synthesized as air-stable emissive red solids using the bulky 1,1,3,3,5,5,7,7-octaethyl-s-hydrindacen-4-yl (Eind) groups. The strong π-π* absorptions and distinct emission at room temperature, both in solution and in the solid state, have been observed due to the substantial contribution of the 3p(π)*(Si-Si)-2p(π)*(carbon π-electron system) conjugation. 相似文献
105.
106.
Takashi Nishikazea Mitsuo Takayama 《Journal of the American Society for Mass Spectrometry》2010,21(12):1979-1988
Although conventional N-Cα bond cleavage in electron capture dissociation (ECD) of multiply-charged peptides generates a complementary
c′ and z′ fragment pair, the N-Cα cleavage followed by hydrogen transfer from c′ to z′ fragments produces other fragments,
namely c′ and z′. In this study, the influence of charge state and amino acid composition on hydrogen transfer in ECD is described
using sets of peptides. Hydrogen transferred ionic species such as c′ and z′ were observed in ECD spectra of doubly-protonated
peptides, while the triply-protonated form did not demonstrate hydrogen transfer. The extent of hydrogen transfer in ECD of
doubly-protonated peptides was dependent on constituent amino acids. The ECD of doubly-protonated peptides possessing numerous
basic sites showed extensive hydrogen transfer compared with ECD of less basic peptides. The extent of hydrogen transfer is
discussed from the viewpoints of the structure of peptide ions, the possibility of internal hydrogen bonding and intermediate
lifetime of complex [c′+z′]. 相似文献
107.
We have performed high-resolution spin- and angle-resolved photoemission spectroscopy of bismuth thin film on Si(111) to investigate the spin structure of surface states. Unlike the conventional Rashba splitting, the magnitude of the in-plane spin polarization is asymmetric between the two elongated surface hole pockets across the zone center. Moreover, we uncovered a giant out-of-plane spin polarization as large as the in-plane counterpart which switches the sign across the Γ-M line. We discuss the present finding in terms of the symmetry breaking and the many-body effects. 相似文献
108.
109.
110.
Ikuma N Tsue H Tsue N Shimono S Uchida Y Masaki K Matsuoka N Tamura R 《Organic letters》2005,7(9):1797-1800
[reaction: see text] Enantiomerically enriched samples of chiral cyclic nitroxides with a 4-hydroxyphenyl group on the stereogenic center bearing the NO radical group undergo unprecedented spontaneous racemization and/or epimerization in aprotic solvents, which can be well accounted for by the multistep equilibrations involving planar quinoid intermediates. 相似文献