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971.
Wang L Zhang W Sheng Su D Meng X Xiao FS 《Chemical communications (Cambridge, England)》2012,48(44):5476-5478
Au nanoparticles with small sizes (1-4 nm) were effectively formed on Mg-Al mixed oxides (Au/MAO), which showed superior catalytic performances and good recyclability in aerobic homocoupling of phenylboronic acid. 相似文献
972.
Tran Duc Thiep Truong Thi An Nguyen Tuan Khai Nguyen The Vinh Phan Viet Cuong Iu. P. Gangrski A. G. Belov O. D. Maslov 《Physics of Particles and Nuclei Letters》2012,9(8):648-655
We have determined the total bremsstrahlung photon fluxes with end-point energies in the giant dipole resonance (GDR) region produced by electron accelerator Microtron MT??25 (the Flerov Laboratory of Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia) and that of 65 MeV bremsstrahlung produced by the linear electron accelerator (the Pohang Neutron Facility, Pohang, South Korea). The method that we used was the photon activation technique. To ensure the accuracy of the results, we carried out simultaneous photon activation of two monitors made of Cu and Au foils in the same irradiation conditions. The results are discussed in the paper. 相似文献
973.
Nanostructured topological insulator materials such as ultrathin films, nanoplates, nanowires, and nanoribbons are attracting much attention for fundamental research as well as potential applications in low-energy dissipation electronics, spintronics, thermoelectrics, magnetoelectrics, and quantum computing due to their extremely large surface-to-volume ratios and exotic metallic edge/surface states. Layered Bi2Se3 and Bi2Te3 serve as reference topological insulator materials with a large nontrivial bulk gap up to 0.3 eV (equivalent to 3600 K) and simple single-Dirac-cone surface states. In this mini-review, we present an overview of recent advances in nanostructured topological insulator Bi2Se3 and Bi3Te3 from the viewpoints of controlled synthesis and physical properties. We summarize our recent achievements in the vapor-phase synthesis and structural characterization of nanostructured topological insulator Bi2Se3 and Bi2Te3, such as nanoribbons and ultrathin nanoplates.We also demonstrate the evolution of Raman spectra with the number of few-layer topological insulators, as well as the transport measurements that have succeeded in accessing the surface conductance and surface state manipulations in the device of topological insulator nanostructures. 相似文献
974.
975.
Viet Duc La 《Journal of sound and vibration》2012,331(15):3429-3436
A passive dynamic vibration absorber (DVA) moving along a pendulum can cause the nonlinear Coriolis damping to reduce the pendulum swing. This paper proposes a simple semi-active on–off damping controller to improve the passive Coriolis DVA. The aim of the on–off damping control is to amplify the DVA resonance motion to increase the energy dissipated. Moreover, the paper finds the analytical solution of the harmonic vibration of semi-active controlled system. The accuracy of the analytical formulas and the superior performance of the semi-active DVA are verified by numerical simulations. 相似文献
976.
977.
Daschbach JL Chang TM Corrales LR Dang LX McGrail P 《The journal of physical chemistry. B》2006,110(35):17291-17295
Molecular dynamics simulations are used to investigate the molecular interactions of hydrogen-loaded beta-hydroquinone clathrate. It is found that, at lower temperatures, higher loadings are more stable, whereas at higher temperatures, lower loadings are more stable. Attractive forces between the guest and host molecules lead to a stabilized minimum-energy configuration at low temperatures. At higher temperatures, greater displacements take the system away from the shallow energy minimum, and the trend reverses. The nature of the cavity structure is nearly spherical for a loading of one, leads to preferential occupation near the hydroxyl ring crowns of the cavity with a loading of two, and at higher loadings, leads to occupation of the interstitial sites (the hydroxyl rings) between cages by a single H(2) molecule with the remaining molecules occupying the equatorial plane of the cavity. Occupation of the interstitial positions of the cavities leads to facile diffusion. 相似文献
978.
Dang TT Albrecht U Gerwien K Siebert M Langer P 《The Journal of organic chemistry》2006,71(6):2293-2301
The one-pot cyclization of dilithiated oximes with epibromohydrin provided a convenient and regioselective approach to 6-hydroxymethyl-5,6-dihydro-4H-1,2-oxazines. The reaction of the latter with phosphorus tribromide resulted in a Beckmann rearrangement and formation of 5-bromomethyl-2-iminotetrahydrofurans. The reaction of dilithiated hydrazones with epibromohydrin afforded oxazolo[3,4-b]pyridazin-7-ones, which were formed by a novel domino cyclization. 相似文献
979.
The sorption of selenite from aqueous solutions onto hematite was investigated as a function of pH (2-12), ionic strength (0.01-0.1 M), and concentration of selenium (10(-7)-10(-2) M). The sorption may proceed according to two processes: surface complexation, followed by the precipitation of ferric selenite starting at approximate [Se] = 4 x 10(-4) M (surface coverage>ca. 2 at nm(-2)). The sorption isotherms have been fitted by a Tempkin equation. A surface complexation model (2-pK/Constant Capacitance Model) was used to fit the sorption data. The nature of the surface species of selenite cannot be determined by modeling since monodentate >FeOSe(O)O- or >FeOSe(O)OH and bidentate (>FeO)2SeO surface complexes are both able to fit the experimental data. The reversibility and kinetics of sorption were also studied. The affinity of selenite ions toward hematite, expressed as the distribution coefficient with respect to the surface area (K(D) in L m(-2)), was compared with results published for other ferric oxides (goethite and amorphous ferric oxide). It was found that the reactivity toward selenite is similar, contrary to acid-base properties which depend on the nature of the oxide and its level of purity. 相似文献
980.
Wolfgang Stadlbauer Anna E. Tubl Hoai V. Dang Claudia Reidlinger Klaus Zangger 《Journal of heterocyclic chemistry》2006,43(1):117-125
4‐Chloro‐ or 4‐tosyloxyquinolines 1 and 10 react with CH‐acidic compounds such as malonates 2a,b , ethyl cyanoacetate ( 2c ), malononitrile ( 2d ), ethyl acetoacetate ( 2e ), acetylacetone ( 2f ) or dimedone ( 2g ) under mild conditions and good yields to quinolin‐4‐yl substituted derivatives 3‐8 and 11 . With 3‐phenylsulfonylquinolones 1i‐k a redox reaction to 2‐hydroxy‐2‐quinolin‐4‐yl‐malonates 9 was observed. Amination of 3‐nitroquinolinyl malonate 3f leads to malonester‐amides 13 and 14 . 相似文献