谁说它只能用来喝饮料

1根塑料吸管有何用？顶多用来喝饮料罢了。可1000根塑料吸管呢？或者更多一点,10000根塑料吸管呢？很多艺术家都先我们一步思考,以实际行为告诉了我们答案。小小的塑料吸管在他们手中变化出各种极具创意的造型。这下,谁还会说塑料吸管只能用来喝饮料呢？     

Oxidative coupling of methane over promoted strontium chlorapatite

Strontium zirconium phosphate, unpromoted strontium chlorapatite and strontium hydroxyapatite showed low C₂ selectivity for the oxidative coupling of methane, but promoted strontium chlorapatite catalysts showed markedly increased activity and selectivity and also exhibited stable behavior. SrCl₂ was the primary promoter and strontium zirconium oxides were considered to be acting as other promoters, but strontium zirconium phosphate and strontium carbonate seemed to be acting adversely. A promoted strontium chlorapatite catalyst which contained a slightly larger amount of SrCl₂ than needed to form the chlorapatite showed the best performance and was stable up to 50 h at 1,023 K, and the highest C₂₊ selectivity and yield were 52% and 13.8%, respectively. Although SrCl₂ was more stable than NaCl it decomposed slowly during the reaction, leaving strontium oxide or strontium carbonate behind, which is considered to result in slow deactivation of the catalyst.     

A computational study on optimal design for organic tandem solar cells

A new model is developed by combining the optical model and the drift-diffusion model to optimize the thicknesses of active layers of individual sub-cells for high performance of organic tandem solar cell. When the photovoltaic properties of tandem organic solar cells based on poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta (2,1-b;3,4-b′) dithiophene)-alt-4,7-(2,1,3-benzo-thiadiazole))/(6,6)-phenyl C71-butyric acid methyl ester and poly(3-hexylthiophene)/(6,6)-phenyl C61-butyric acid methyl ester are calculated as functions of thicknesses of individual sub-cells using the new model, it is found that the optimum thickness pair of active layers is 150 and 120 nm for the front and back sub-cell, respectively. Comparison of simulation with experiment reveals that the simulated results are very consistent with experimental ones.     

Numerical study for laminar wavy motions of liquid film flow on vertical wall

Film flows are classified into non-wavy laminar, wavy laminar and turbulence along the Reynolds number or the flow stability. Since the wavy motions of the film flows are so intricate and nonlinear, the studies have largely been dependent upon the experimental way. The numerical approaches have been limited on the non-wavy flow regime. To track the free surface position, various numerical techniques such as the VOF (Volume of Fluids), the MAC (Marker and Cell) and the moving grid have been adopted. However those were for a more accurate estimation of the average film thickness and not for capturing the wavy motion. Because the wavy motion highly affects the heat transfer in the film flow, the profound concern for the wavy motion is significant. In this study, the wavy motions of the laminar wavy film flow with the Reynolds number 200–1000 are successfully found by the VOF and PLIC (Piecewise Linear Interface Calculation) method. The numerical results, including the average film thickness, and the wave’s amplitude, frequency and velocity, are compared with the experimental results.     

Steady-flow characteristics and its influence on spray for direct injection diesel engine

Flow and spray characteristics are critical factors that affect the performance and exhaust emissions of a direct injection diesel engine. It is well known that the swirl control system is one of the useful ways to improve the fuel consumption and emission reduction rate in a diesel engine. However, until now there have only been a few studies on the effect of flow on spray. Because of this, the relationship between the flow pattern in the cylinder and its influence on the behavior of the spray is in need of investigation. First, in-cylinder flow distributions for 4-valve cylinder head of Dl (Direct Injection) Diesel engine were investigated under steady-state conditions for different SCV (Swirl Control Valve) opening angles using a steady flow rig and 2-D LDV (Laser Doppler Velocimetry). It was found that swirl flow was more dominant than that of tumble in the experimented engine. In addition, the in-cylinder flow was quantified in terms of swirl/tumble ratio and mean flow coefficient. As the SCV opening angle was increased, high swirl ratios more than 3.0 were obtained in the case of SCV -70ΰ and 90ΰ. Second, spray characteristics of the intermittent injection were investigated by a PDA (Phase Doppler Anemometer) system. A Time Dividing Method (TDM) was used to analyze the microscopic spray characteristics. It was found that the atomization characteristics such as velocity and SMD (Sauter Mean Diameter) of the spray were affected by the in-cylinder swirl ratio. As a result, it was concluded that the swirl ratio improves atomization characteristics uniformly.     

E-auction web assessment model in China

Electronic auction (e-auction), a major e-commerce model, has enjoyed rapid growth in many countries. This study develops a web assessment model (EAWAM) from a consumer perspective that suggests that user intention to continue using an e-auction website is based on users’ satisfaction with the e-auction website, which is determined by perceived e-auction user friendliness, functionality and interactivity. Web trustworthiness serves as an important antecedent to perceived e-auction user friendliness and functionality. To validate this model, a survey was conducted using 191 users of Taobao.com from 15 cities in China. Partial Least Square analysis results provided strong support for this model and also yielded important implications and suggestions for further research.     

Absorption of D(g) atoms in ultrathin Mg films and Pd-catalyzed decomposition of MgD2

We have investigated the interaction of the gas-phase D atoms with ultrathin Mg films thermally evaporated on SiO₂ by temperature programmed desorption. The gas-phase D atoms impinging upon a Mg (100 Å) film directly penetrate into the bulk with a constant probability of 0.22 until the top 16 Å is deuterated, whereafter the MgD₂(s) growth quickly slows down. Upon heating the partially deuterated Mg film, Mg atoms diffuse out to the surface to desorb at the same temperature as a pure Mg film. On the other hand, MgD₂(s) decomposes to result in simultaneous desorption of D₂ and Mg at 590 K with an activation energy of 133 ± 5 kJ/mol. A Pd layer of 20 Å thickness deposited on top of MgD₂(s) acts as a catalyst to greatly reduce the decomposition temperature from 590 to 350 K. We interpret the catalytic effect of Pd in terms of reverse spill-over, in which the surface of Pd clusters in contact with MgD₂(s) provides an intermediate adsorption sites with a low activation energy for the recombinative desorption of D atoms.