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1.
A photoinduced synthesis of β-keto thiosulfone/β-keto selenosulfone by the reaction of α-bromoacetophenone with thiosulfonate/selenosulfonate under metal-free and visible light irradiation conditions is developed. Two C−S bonds or one C−S bond and one C−Se bond were constructed simultaneously.  相似文献   
2.
    
We present a rigorous theoretical model for the influence of the aperture in interferometric out-of-focus imaging. We investigate the role of this effect on the properties of speckle-like patterns generated by irregular, rough particles. Finally, we determine the conditions under which these patterns are no longer representative of particle size but of the aperture itself and the defocus parameter.  相似文献   
3.
    
《Journal of Crystal Growth》2006,286(2):205-208
We demonstrated seeded growth of AlN on large-area Al- and N-polar <0 0 0 1>-oriented AlN seeds using the physical vapor transport method (PVT). In both cases, crystals having a diameter of 15 mm were obtained from 5 mm seeds. Based on growth step and terrace width analyses, it was found that the N-polar face was suitable for growth within a large window of growth parameters while the Al-polar seeds yielded high-quality crystals only at low supersaturation.  相似文献   
4.
    
We present a numerical investigation of breakup modes of an axisymmetric, laminar compound jet of immiscible fluids, which flows in a coflowing immiscible outer fluid. We use a front-tracking/finite difference method to track the unsteady evolution and breakup of the compound jet, which is governed by the Navier–Stokes equations for incompressible Newtonian fluids. Numerical results show that depending on parameters such as the Reynolds number Re (in the range of 5–30) and Weber Number We (in the range of 0.1–0.7), based on the inner jet radius and inner fluid properties, the compound jet can break up into drops in various modes: inner dripping–outer dripping (dripping), inner jetting–outer jetting (jetting), and mixed dripping–jetting. Decreasing Re or increasing We promotes the jetting mode. The transition from dripping to jetting is also strongly affected by the velocity ratios, U21 (intermediate to inner velocities) and U31 (outer to inner velocities). Increasing U21 makes the inner jet thinner and stretches the outer jet and thus promotes jetting. In contrast, increasing U31 thins the outer jet, and thus, when the inner jet is dripping, the outer jet can break up into drops in the mixed dripping–jetting mode. Continuously increasing U31 results in thinning both inner and outer jets and thus produces small drops in the jetting mode. In addition, starting from dripping, a decrease in the interfacial tension ratio of the outer to inner interfaces results in the mixed dripping–jetting and jetting modes. These modes produce various types of drops: simple drops, and compound drops with a single inner drop (single-core compound drops) or a few inner drops (multi-core compound drops).  相似文献   
5.
Cheng  Yao 《Numerical Algorithms》2019,80(4):1329-1359
Numerical Algorithms - In this paper, we present the optimal L2-norm error estimate of the local discontinuous Galerkin method based on the generalized alternating numerical flux for nonlinear...  相似文献   
6.
The purpose of this paper is to study a new two-step iterative scheme with mean errors of mixed type for two asymptotically nonexpansive self-mappings and two asymptotically nonexpansive nonself-mappin...  相似文献   
7.
    
《中国化学快报》2020,31(9):2330-2332
By integrating the merits of lanthanide elements and quantum dots, we firstly design CeO2 quantum dots doped Ni-Co hydroxide nanosheet via a controllable synthetic strategy, which exhibits a large specific capacitance (1370.7 F/g at 1.0 A/g) and a good cyclic stability (90.6% retention after 4000 cycles). Moreover, we assemble an aqueous asymmetric supercapacitor with the obtained material, which has an extremely high energy density (108.9 Wh/kg at 378 W/kg) and outstanding cycle stability (retaining 88.1% capacitance at 2.0 A/g after 4000 cycles).  相似文献   
8.
    
Broadband light absorption and excellent charge separation/migration efficiency are two important indicators for promising photocatalyst. However, realizing the above two aspects simultaneously is still a challenge. Here, an ultrathin and broadband carbon nitride (UBCN) is synthesized via a short-time thermal oxidation process. The as-prepared UBCN exhibits outstanding photocatalytic H2 generation activity (240.60 μmol h−1) under irradiation with λ>400 nm. Moreover, UBCN can work under irradiation with a longer wavelength (λ>500 nm), the corresponding H2 evolution rate is 5.08 μmol h−1, which is 14.8 times higher than that of bulk carbon nitride (Bulk CN). The excellent photocatalytic performance should be credited to the efficient charge separation/migration (the ultrathin structure) and the extended light absorption range. This work provides a simple and convenient strategy to prepare broadband and ultrathin metal-free photocatalytic materials.  相似文献   
9.
    
Developing non-noble metal catalysts for methanol oxidation in fuel cells is of importance. In this work, Ni-MOF-74 was synthesized through a simple solvothermal method and fully characterized. The as-made Ni-MOF-74 modified carbon paste electrode (Ni-MOF-74/CPE) was applied for methanol electrooxidation reaction in 0.1 M NaOH solution. Ni-MOF-74 had high electrochemical stability and exhibited good electrocatalytic property for methanol oxidation, a mechanism for the reaction was proposed, the current density increases impressively on Ni-MOF-74/CPE compared with carbon paste electrode, and a really high catalytic rate constant (kcat) of 8.1×105 cm3 ⋅ mol−1 ⋅ s−1 was obtained in this work. The given results indicate that Ni-MOF-74 can be a promising candidate of electrocatalysts for direct methanol fuel cells (DMFCs).  相似文献   
10.
在量子通讯的实验中,由于外界环境的影响,我们很难得到最大的纠缠纯态.量子信道可能以混合纠缠态的形式出现.而固体材料中的热平衡态就是一种重要的混合纠缠态.本文利用了两个独立的外加不均匀磁场的一维海森堡链的热纠缠态作为量子信道,实现了两粒子纠缠态的远程传送,分析了外界温度和磁场对纠缠和传输保真度的影响.为了突出传输效果,我们对平均保真度做了研究,结果发现当温度很低,外加反方向的磁场B1和B2时,平均保真度大于经典通道的传输极限值2/3.  相似文献   
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