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81.
In the presence of a catalytic amount of ammonium chiral borate salt, asymmetric Friedel-Crafts alkylation of indoles with α,β-disubstituted enals proceeded to give the corresponding 1,4-addition products with moderate enantioselectivities. 相似文献
82.
Stretch-flangeability is an important formability factor for advanced high-strength steels (AHSS) when manufacturing automotive parts. However, the reproducibility of the hole expansion test (HET), a standard testing method established by the international organization for standardization, is quite poor compared with other mechanical testing methods. In this study, we propose a new method, the sheared-edge tensile test (SETT), for evaluating stretch-flangeability with excellent reproducibility. SETT takes into account the deformation behavior during the HET and the critical extrinsic factors influencing the hole expansion ratio (HER). The correlation between the sheared-edge surface characteristics, the tensile properties of the SETT specimen, and stretch-flangeability were investigated to gain in-depth understanding of the proposed evaluation method. Although the correlation between HER and the post-uniform elongation of the SETT specimen with an HER >80% was ambiguous, the SETT results exhibited good reproducibility, and the stretch-flangeability indicated by HER tended to increase linearly with increases in the post-uniform elongation of the SETT specimen. Furthermore, the roughness of the sheared-edge surface had a significant effect on the local deformation behavior of the materials. The proposed method requires only a small amount of specimen, as compared with the HET and can evaluate stretch-flangeability with good reproducibility. 相似文献
83.
Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels
Seung Hwan Ko Daeho Lee Heng Pan Sang-Gil Ryu Costas P. Grigoropoulos Nick Kladias Elias Panides Gerald A. Domoto 《Applied Physics A: Materials Science & Processing》2010,100(2):391-400
Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel
are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the
thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the
speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acoustic
wave in various internal channel structures ((a) sudden expansion and contraction channels, (b) bifurcating channels, (c) gradual
contraction wall channels and (d) a cylinder). Fairly good agreement between the experimental results and numerical simulation
is observed. 相似文献
84.
Young Bok Ryu Ji Sun Kim Kyeong Ho Kim Yangdo Kim Man Sig Lee 《Research on Chemical Intermediates》2016,42(1):83-93
Zn/Al mixed oxide was prepared by the coprecipitation or the hydrothermal method under different conditions and used as catalyst for synthesis of glycerol carbonate by carbonylation of glycerol with urea. The physical properties of the prepared Zn/Al mixed oxide particles were investigated, as well as their activity as catalyst in the mentioned synthesis. The dried Zn/Al mixed-oxide particles prepared by the coprecipitation method showed higher activity in synthesis of glycerol carbonate than those prepared by the hydrothermal method. The Zn/Al mixed oxide prepared by the coprecipitation method without NaNO3 showed the highest catalytic activity in synthesis of glycerol carbonate. 相似文献
85.
[reaction: see text] The above reaction is much faster with Y = CF(3)CH(2)O than with Y = CH(3)O. However, the methyl ester is a strong inhibitor of the Diels-Alder reaction of the trifluoroethyl ester, since it has a higher affinity for the catalyst 1. 相似文献
86.
It has been known since the early days of plasma physics research that superthermal electrons are generated during beam-plasma laboratory experiments. Superthermal electrons (the kappa distribution) are also ubiquitously observed in space. To explain such a feature, various particle acceleration mechanisms have been proposed. However, self-consistent acceleration of electrons in the context of plasma kinetic theory has not been demonstrated to date. This Letter reports such a demonstration. It is shown that the collisionality, defined via the "plasma parameter" g=1/n(lambda(D)(3), plays a pivotal role. It is found that a small but moderately finite value of is necessary for the superthermal tail to be generated, implying that purely collisionless (g=0) Vlasov theory cannot produce a superthermal population. 相似文献
87.
88.
Anion complexation. A ditriphenylphosphonium calix[4]arene derivative as a novel receptor for anions
A novel anionic receptor 2 consisting of a calix[4]arene bearing two alkytriphenylphosphonium has been prepared by two different procedures. The complexation occurred at the phosphonium sites probably due to electrostatic and/or π-anion forces. 相似文献
89.
Ryu Sasaki 《Czechoslovak Journal of Physics》2003,53(11):1111-1117
The relationship (resemblance and/or contrast) between quantum and classical integrability in Ruijsenaars-Schneider (R-S) and Calogero-Moser systems is addressed. The classical Calogero and Sutherland systems (based on any root system) at equilibrium have many remarkable properties; for example, the minimum energies, frequencies of small oscillations and the eigenvalues of Lax pair matrices at equilibrium are all integer valued. These are related to the energy eigenvalues of the quantum Calogero and Sutherland systems. Similar features and results hold for the R-S type of integrable systems based on the classical root systems. 相似文献
90.
Photoelectrochemical decomposition of water on nanocrystalline BiVO4 film electrodes under visible light 总被引:1,自引:0,他引:1
Sayama K Nomura A Zou Z Abe R Abe Y Arakawa H 《Chemical communications (Cambridge, England)》2003,(23):2908-2909
The nanocrystalline BiVO4 film electrode on conducting glass showed an excellent efficiency (IPCE = 29% at 420 nm) for the decomposition of water under visible light. 相似文献