Deposition of c-axis orientation aluminum nitride films on flexible polymer substrates by reactive direct-current magnetron sputtering

Aluminum nitride (AlN) piezoelectric thin films with c-axis crystal orientation on polymer substrates can potentially be used for development of flexible electronics and lab-on-chip systems. In this study, we investigated the effects of deposition parameters on the crystal structure of AlN thin films on polymer substrates deposited by reactive direct-current magnetron sputtering. The results show that low sputtering pressure as well as optimized N 2/Ar flow ratio and sputtering power is beneficial for AlN (002) orientation and can produce a highly (002) oriented columnar structure on polymer substrates. High sputtering power and low N 2/Ar flow ratio increase the deposition rate. In addition, the thickness of Al underlayer also has a strong influence on the film crystallography. The optimal deposition parameters in our experiments are: deposition pressure 0.38 Pa, N 2/Ar flow ratio 2:3, sputtering power 414 W, and thickness of Al underlayer less than 100 nm. © 2012 Elsevier B.V. All rights reserved.

Room-temperature remote-plasma sputtering of c-axis oriented zinc oxide thin films

Highly c-axis oriented ZnO films have been deposited at room temperature with high rates (∼50 nm·min -1) using an innovative remote plasma sputtering configuration, which allows independent control of the plasma density and the sputtering ion energy. The ZnO films deposited possess excellent crystallographic orientation, high resistivity (>10 9 Ω·m), and exhibit very low surface roughness. The ability to increase the sputtering ion energy without causing unwanted Ar + bombardment onto the substrate has been shown to be crucial for the growth of films with excellent c-axis orientation without the need of substrate heating. In addition, the elimination of the Ar + bombardment has facilitated the growth of films with very low defect density and hence very low intrinsic stress (100 MPa for 3 μm-thick films). This is over an order of magnitude lower than films grown with a standard magnetron sputtering system. © 2012 American Institute of Physics.

饲料中不同维生素C���量对长吻的影响

用维生素C���量为38、364和630mg/kg的三种饲料饲喂初体重为(23.19±0.58)g的长吻8个月,实验结果表明,38mg/kgVC���料组饲喂的长吻表现出了典型的VC���乏症状:体色发黑,脊椎侧弯,鳍边由开始的萎缩直到腐烂、贫血、特定生长率显著降低(p<0.05)。并且38mg/kgVC���料组长吻的生理指标也受到影响:血清溶菌酶活性显著下降(p<0.05),肝脏的SOD活性及MDA含量均显著升高(p<0.05),血清皮质醇没有显著差异(p>0.05),但各处理组长吻肝脏中均未检测到诱导型HS

低C/N对湿地中硝化反硝化作用的影响

通过监测几种形态氮的变化,研究了人工湿地小试系统在不同浓度和低C/N条件下的除氮效果和反硝化途径.结果发现,湿地对浓度为5.5～50.5mg/L的NH4+-N有很好的去除效果,去除率可达95%以上.在此浓度范围内,NH4+-N的进、出水浓度呈线性关系,R2值为0.9971.当进水含氮量低于16.4mg/L时,湿地的除氮效率随进水浓度的增加而明显增加.进水含氮量为16.4～51.4mg/L时,湿地的除氮效率为85%以上,且浓度对去除率无显著影响.当C/N<1时,湿地系统对总氮的去除率为86.3%,而碳源充足

3D modeling of high-T c superconductors by finite element software

A three-dimensional (3D) numerical model is proposed to solve the electromagnetic problems involving transport current and background field of a high-T c superconducting (HTS) system. The model is characterized by the E-J power law and H-formulation, and is successfully implemented using finite element software. We first discuss the model in detail, including the mesh methods, boundary conditions and computing time. To validate the 3D model, we calculate the ac loss and trapped field solution for a bulk material and compare the results with the previously verified 2D solutions and an analytical solution. We then apply our model to test some typical problems such as superconducting bulk array and twisted conductors, which cannot be tackled by the 2D models. The new 3D model could be a powerful tool for researchers and engineers to investigate problems with a greater level of complicity.