Influence of Geometric Tooth Shape Parameters of Labyrinth Seals on the Flow Law and the Algorithm for Designing Straight Grate Teeth

Russian Physics Journal - In view of the fact that the traditional method does not summarize flow rules through straight labyrinth seals, there is no rule to summarize the sealing effects of the...     

Improving photovoltaic parameters of all-polymer solar cells through integrating two polymeric donors

Science China Chemistry - The incorporation of an additional component into the bulk-heterojunction light-harvesting layer of polymer solar cells has been considered as an effective strategy to...     

Density functional theory for adsorption of HCHO on the FeO（100） surface

The density functional theory (DFT) and periodic slab model were used to get information concerning the adsorption of HCHO on the FeO(100) surface. A preferred η2-(C,O)-di-σ four-membered ring adsorption conformation on the Fe-top site was found to be the most favorable structure with the predicted adsorption energy of 210.7 kJ/mol. The analysis of density of states, Mulliken population, and vibrational frequencies before and after adsorption showed clear weakening of the carbonyl bond, and high sp3 charact...     

兆焦耳级高功率激光驱动器光机结构设计

兆焦耳级高功率激光驱动器是实现激光惯性约束聚变点火的必备手段,光机结构是兆焦耳激光装置的重要组成部分。对美国国家点火装置（NIF）和法国兆焦耳激光装置（LMJ）的总体结构进行了概述和分析,对神光-Ⅲ激光装置的结构特点进行了介绍,并对重要光机模块的结构特点及安装使用情况进行了分析,对总体集成技术和A6的安装集成情况进行了总结。     

Growth mechanism of palladium clusters on rutile TiO2 （110） surface

Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n (n=1-5) clusters adsorbed on TiO2 (110) surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states (TSs) search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional (3D) models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.     

Scaling up of high-speed countercurrent chromatographic apparatus with three columns connected in series for rapid preparation of (−)-epicatechin

In the present study, compact high-speed countercurrent chromatographic apparatus was constructed with three columns connected in series. Two sets of columns were prepared from 10 mm and 12 mm I.D. tubing to form 12 L and 15 L capacities, respectively. Performance of these columns was compared for the separation of (−)-epicatechin gallate (ECG) from a tea extract by flash countercurrent chromatography (FCCC). In each separation, 200 g of the tea extract in 1600 mL of mobile phase was loaded onto the column. The 12 L column gave 7.5 L (35 g of ECG) and the 15 L column gave 9 L (40 g of ECG) of ECG solution without impurities. The ECG solution was directly hydrolyzed by tannase into (−)-epicatechin. The hydrolysate was purified by flash chromatography on AB-8 macroporous resin to give 52 g of EC (purity 99.1%). This scaled up apparatus could be used for the industrial separation of natural products.     

Isolation of the retinal isomers from the isomerization of all-trans-retinal by flash countercurrent chromatography

The isolation of the retinal isomers from all-trans-retinal was performed by flash countercurrent chromatography. In each separation, isomerization reaction solution of 200 mg all-trans-retinal could be loaded on a 1200 mL of high-speed countercurrent chromatographic column with 5 mm bore, eluted by a mobile phase flow rate of 25 mL/min, resulting in 63 mg of 11-cis-retinal, 24 mg of 13-cis-retinal and 26 mg of 9-cis-retinal with purities more than 95%. n-Hexane–acetonitrile (3:1) was used as the solvent system which possesses the advantages of simplicity, re-use of the solvent and multiple injections. This method could be used to prepare 13-cis-retinal, 11-cis-retinal and 9-cis-retinal for the photoisomerization investigation, such as the effect of 11-cis-retinal in the visual system.     

Structural and electronic properties of tungsten trioxides: from cluster to solid surface

Geometries and electronic structures of WO₃(001) surface and a series of stoichiometric (WO₃) _n clusters (n = 1–6) have been systematically investigated using first-principles density functional calculations. Six possible reconstructured models of WO₃(001) surface with cubic phase are explored, and the most stable configuration is the \( (\sqrt 2 \times \sqrt 2 )R45^{\circ} \) surface. The main feature of WO₃(001) surface is that the top of valence band is dominated by the 2p states of the bridging oxygen atom, rather than the top terminal oxygen. By comparing the geometrical parameters, from the structural point of view, the W₃O₉ cluster can be used as the smallest molecular prototype of the WO₃ surface. However, in terms of the electronic structure, only until W₆O₁₈, the cluster begins to appear the electronic feature of the WO₃(001) surface. This may be due to the reason that the W₆O₁₈ cluster and the top layer of WO₃(001) surface show similar “stoichiometry” if we treat two kinds of oxygen atoms as different “elements”. In addition, for the chemical reactivity, using BH₃ as a probe molecule, the W₆O₁₈ cluster also bears general resemblance to the WO₃(001) surface, and the bridging oxygen atoms in two systems are the preferred sites for the nucleophilic reaction. Therefore, our results indicate that the W₆O₁₈ cluster with a spherical buckyball structure can be viewed as the smallest molecular model to understand the properties such as catalytic activity of WO₃(001) surface.