Highly selective copper‐catalyzed oxidation of benzyl alcohols to aromatic aldehydes in water at room temperature

Water‐soluble 2N2O–Cu(II) complexes were synthesized and used for the catalytic oxidation of benzylic alcohols to the corresponding aldehydes in pure water resulting in high yields of up to 94%. Importantly, the catalytic system exhibits a wide substrate scope, high functional group tolerance and can be reused directly for subsequent reaction cycles. Using this catalytic system, the product 4‐methylbenzaldehyde can be produced on a multi‐gram scale and in the complete absence of any organic solvent, surfactant or phase transfer reagent. Copyright © 2016 John Wiley & Sons, Ltd.     

Laser-induced voltage characteristics of Bi2Sr2Co2Oy thin films on LaAlO3 substrates

We report the laser-induced voltage (LIV) effects in c-axis oriented Bi₂Sr₂Co₂O_y thin films grown on (0 0 1) LaAlO₃ substrates with the title angle α of 0°, 3°, 5° and 10° by a simple chemical solution deposition method. A large open-circuit voltage with the sensitivity of 300 mV/mJ is observed for the film on 10° tilting LaAlO₃ under a 308 nm irradiation with the pulse duration of 25 ns. When the film surface is irradiated by a 355 nm pulsed laser of 25 ps duration, a fast response with the rise time of 700 ps and the full width at half maximum of 1.5 ns is achieved. In addition, the experimental results reveal that the amplitude of the voltage signal is approximately proportional to sin 2α and the signal polarity is reversed when the film is irradiated from the substrate side rather than the film side, which suggests the LIV effects in Bi₂Sr₂Co₂O_y thin films originate from the anisotropic Seebeck coefficient of this material.     

The effect of microstructure on the laser-induced transverse voltage in Pb-doped Bi2Sr2Co2O y thin films on tilted substrates

Pb-doped Bi₂Sr₂Co₂O _y thin films were prepared on tilted LaAlO₃(001) by using the chemical solution deposition technique under different annealing temperatures and its laser-induced transverse voltage effect was investigated by using a 308 nm pulsed radiation. The shape of the laser-induced voltages in these films depended strongly on the film microstructure. Films with a larger grain size and better crystalline quality had a voltage signal with greater amplitude and faster response time. The experimental results can be explained by a mechanism involving the transverse thermoelectric effect as well as the transport theory of thermoelectric materials.     

On the limit cycles,period-doubling,and quasi-periodic solutions of the forced Van der Pol-Duffing oscillator

In this paper, the limit cycles, period-doubling, and quasi-periodic solutions of the forced Van der Pol oscillator and the forced Van der Pol-Duffing oscillator are studied by combining the homotopy analysis method (HAM) with the multi-scale method analytically. Comparisons of the obtained solutions and numerical results show that this method is effective and convenient even when t is large enough, and the convergence of the approximate solutions is discussed by the so-called discrete square residual error. This method is a capable tool for solving this kind of nonlinear problems.     

齐次Morrey-Herz空间上粗糙核高阶交换子的有界性

在齐次Morrey-Herz空间上建立了由粗糙核算子T与BMO(R~n)函数生成的高阶交换子T_(b,m)的有界性.同时对Hardy-Littlewood极大粗糙算子和相应的分数次极大粗糙算子所生成的高阶交换子也得到了相应的结果.     

Laser-induced lateral voltage in epitaxial Al-doped ZnO thin films on tilted sapphire

Laser-induced voltage effects in epitaxial Al-doped ZnO thin films on tilted sapphire have been experimentally studied at room temperature. An open-circuit lateral voltage signal with nanosecond response time was observed when the film surface was irradiated by laser pulses of 308 nm and 1064 nm, and the voltage responsivity of the signal for 308-nm irradiation is much higher than that for 1064-nm irradiation. A mechanism based on the thermoelectric effect is proposed to explain the origin of the laser-induced lateral voltage in this system. The result suggests that the Al-doped ZnO thin films have a potential application in wide-band photodetectors from ultraviolet to near infrared.     

Synthesis of the azaphilones (+)-sclerotiorin and (+)-8-O-methylsclerotiorinamine utilizing (+)-sparteine surrogates in copper-mediated oxidative dearomatization

Enantioselective syntheses of the azaphilone natural products (+)-sclerotiorin and (+)-8-O-methylsclerotiorinamine that possess the natural R-configuration at the quaternary center are reported. The syntheses were accomplished using copper-mediated asymmetric dearomatization employing bis-μ-oxo copper complexes prepared from readily available (+)-sparteine surrogates. Of note, site-selective O-methylation of a vinylogous pyridone was used to access the isoquinolin-6(7H)-one core of (+)-8-O-methylsclerotiorinamine.