李渔戏剧"宾白"论

戏剧是一门综合艺术.作为戏剧语言之一的宾白在剧本构成中占有特别重要的地位,但在实际创作中,"宾白"却一直得不到应有的重视.李渔在前人研究的基础上,结合自己的创作和对家庭戏班悉心教诲的丰富经验,在理论上大力提高宾白在剧本中的地位、提出宾白创作中的几个标准以及对宾白创作的具体办法,形成了他的"宾白"论.     

Incipient separation in shock wave/boundary layer interactions as induced by sharp fin

The incipient separation induced by the shock wave/turbulent boundary layer interaction at the sharp fin is the subject of the present study. Existing theories for the prediction of incipient separation, such as those put forward by McCabe (1966) and Dou and Deng (1992), can thus far only predic the direction of surface streamline and tend to overpredict the incipient separation condition based on the Stanbrook’s criterion. In this paper, the incipient separation is first predicted with Dou and Deng (1992)’s theory and then compared with Lu and Settles’ (1990) experimental data. The physical mechanism of the incipient separation as induced by the shock wave/turbulent boundary layer interactions at sharp fin is explained via surface flow pattern analysis. Furthermore, the reason for the observed discrepancy between the predicted and experimental incipient separation conditions is clarified. It is found that when the wall-limiting streamlines behind the shock wave becomes aligned with one ray from the virtual origin as the strength of the shock wave increases, the incipient separation line is formed at which the wall-limiting streamline becomes perpendicular to the local pressure gradient. The formation of this incipient separation line is the beginning of the separation process. The effects of Reynolds number and Mach number on incipient separation are also discussed. Finally, a correlation for the correction of the incipient separation angle as predicted by the theory is also given.

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Platinum Group Metal–free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells

Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low‐grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost‐effective. A variety of noble‐metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS₂, carbon‐based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications.     

Simulations of fibre orientation in dilute suspensions with front moving in the filling process of a rectangular channel using level-set method

The simulation of fibre orientation in dilute suspension with front moving is carried out using the projection and level-set methods. The motion of fibres is described using the Jeffery equation, and the contribution of fibres to the flow is accounted for by the configuration-field method. The dilute suspension of short fibres in Newtonian fluids is considered. The governing Navier–Stokes equation for the fluid flow is solved using the projection method with finite difference scheme, while the fibre-related equations are directly solved with the Runge–Kutta method. In the present study for fibres in dilute suspension flow for injection molding, the effects of various flow and material parameters on the fibre orientation, the velocity distributions and the shapes of the leading flow front are found and discussed. Our findings indicate that the presence of fibre motion has little influence on the front shape in the ranges of fibre parameters studied at the fixed Reynolds number. Influence of changing fibre parameters only causes variation of front shape in the region near the wall, and the front shape in the central core area does not vary much with the fibre parameters. On the other hand, the fibre motion has strong influence on the distributions of the streamwise and transverse velocities in the fountain flow. Fibre motion produces strong normal stress near the wall which leads to the reduction of transversal velocity as compared to the Newtonian flow without fibres, which in turn, leads to the increased streamwise velocity near the wall. Thus, the fibre addition to the flow weakens the strength of the fountain flow. The Reynolds number has also displayed significant influence on the distribution of the streamwise velocity behind the flow front for a given fibre concentration. It is also found that the fibre orientation is not always along the direction of the velocity vector in the process of mold filling. In the region of the fountain flow, the fibre near the centreline is more oriented across the streamwise direction compared to that in the region far behind the flow front. This leads to the fact that the fibre near the centreline in the region of fountain flow is more extended along the transverse direction. As the fibre orientation in the suspension flow and the shape of the flow front have great bearing on the quality of the product made from injection molding, this study has much implications for engineering applications. These results can also be useful in other fields dealing with fibre suspensions.     

无序对准PT对称结构中光子传输与相关特性的影响

主要研究了结构无序对光子在由耦合波导阵列构成的准PT对称体系中的传输与相关特性的影响.结果表明,当在准PT对称体系中引入非对角无序之后,由于Anderson局域效应使光子主要聚束在中心波导附近,且相变点变小,并增强了这种非厄米体系的吸收增强透过现象.     

采用颜色纹理及光谱特征的木材树种分类识别

针对木材分类特征的繁多,同科属木材种间差异小,单纯依靠一种特征分类易误识等特点,提出了一种基于模糊BP综合神经网络的新型木材树种分类识别方法.该方法使用分类特征的模糊化处理,充分考虑木材的分类特征本身存在的不确定性;同时使用一种特征级数据融合方法,该综合神经网络包括颜色特征、主要和次要纹理特征和光谱特征4个BP子网络;并用散度进行光谱特征波段的特征选择,还运用遗传算法对网络结构进行优化处理,提高了该综合神经网络的收敛性和稳定性.实验时针对东北地区常见的5种树种(白松、樟子松、落叶松、杨木和桦木)木材进行分类测试,实验结果表明,5种树种木材的混合识别率达到89%,具有较好的分类识别精度.     

季膦离子液体促进的Morita-Baylis-Hillman反应

膦类离子液体,因其好的热稳定性以及在弱碱性介质中的惰性等优异特点,正在受到越来越多的关注.以廉价的三丁基膦和各种卤代烃为原料,制备了一系列季膦离子液体,然后以其与水组成的复合体系为反应介质,在催化剂1,4-二氮杂二环[2.2.2]辛烷(DABCO)作用下,进行了各种醛与丙烯腈、丙烯酸甲酯及丙烯酰胺的Morita-Baylis-Hillman反应研究.实验结果表明,在室温条件下,溴化乙基三丁基膦与水组成的复合溶剂体系,有效地促进了各种芳香醛及脂肪醛的Morita-Baylis-Hillman反应,不仅反应速度快,而且目标产物产率高.     

Innenrücktitelbild: Developing Conjugated Polymers with High Electron Affinity by Replacing a C?C Unit with a B←N Unit (Angew. Chem. 12/2015)

The key parameters of conjugated polymers are lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energy levels. Few approaches can simultaneously lower LUMO and HOMO energy levels of conjugated polymers to a large extent (>0.5 eV). Disclosed herein is a novel strategy to decrease both LUMO and HOMO energy levels of conjugated polymers by about 0.6 eV through replacement of a C C unit by a B←N unit. The replacement makes the resulting polymer transform from an electron donor into an electron acceptor, and is proven by fluorescence quenching experiments and the photovoltaic response. This work not only provides an effective approach to tune the LUMO/HOMO energy levels of conjugated polymers, but also uses organic boron chemistry as a new toolbox to develop conjugated polymers with high electron affinity for polymer optoelectronic devices.     

Analysis of small interfering RNA by capillary electrophoresis in hydroxyethylcellulose solutions

The analysis of small interfering RNA (siRNA) is important for gene function studies and drug developments. We employed CE to study the separation of siRNA ladder marker, which were ten double‐stranded RNA (dsRNA) fragments ranged from 20 to 1000 bp, in solutions of hydroxyethylcellulose (HEC) polymer with different concentrations and molecular weights (Mws). Migration mechanism of dsRNA during CE was studied by the mobility and resolution length (RL) plots. We found that the RL depended on not only the concentration of HEC, but also the Mw of HEC. For instance, RL of small dsRNA fragment was more influenced by concentration of high Mw HEC than large dsRNA fragment and RL of large dsRNA fragment was more influenced by concentration of low Mw HEC than small dsRNA fragment. In addition, we found electrophoretic evidence that the structure of dsRNA was more compact than dsDNA with the same length. In practice, we succeeded to separate the glyceraldehyde 3‐phosphate dehydrogenase siRNA in the mixture of the siRNA ladder marker within 4 min.