Decorating Mn3O4 nanoparticle on NiO nanoflake arrays for high-performance electrochemical biosensors

Journal of Solid State Electrochemistry - Substrate materials play a significant role in the improvement of electrochemical biosensors. In the present work, NiO nanoflake arrays were fully and...     

A faster aggregation for 3D fast evanescent wave solvers using rotations

A novel technique to accelerate the aggregation and disaggregation stages in evanescent plane wave methods is presented. The new method calculates the six plane wave radiation patterns from a multipole expansion (aggregation) and calculates the multipole expansion of an incoming field from the six plane wave incoming field patterns. It is faster than the direct approach for multipole orders larger than one, and becomes six times faster for large multipole orders. The method relies on a connection between the discretizations of the six integral representations, and on the fact that the Wigner D-matrices become diagonal for rotations around the z-axis. The proposed technique can also be extended to the vectorial case in two different ways, one of which is very similar to the scalar case. The other method relies on a Beltrami decomposition of the fields and is faster than the direct approach for any multipole order. This decomposition is also not limited to evanescent wave solvers, but can be used in any vectorial multilevel fast multipole algorithm.     

Dielectric and piezoelectric properties of Fe2O3-doped (Na0.5K0.5)0.96Li0.04Nb0.86Ta0.1Sb0.04O3 lead-free ceramics

The effect of a small amount Fe₂O₃ (0.1-2 mol%) doping on the electrical properties of (Na_0.5K_0.5)_0.96Li_0.04Nb_0.86Ta_0.1Sb_0.04O₃ (NKLNTS) ceramics was investigated. It was found that the B-site substitution of Fe³⁺ does not change the crystal structure within the studied doping level and all modified ceramics have a pure tetragonal perovskite structure at room temperature. The addition of Fe₂O₃ can promote the sintering of NKLNTS ceramics, and simultaneously cause the grain growth so that Fe³⁺-doped NKLNTS compositions show degraded densification at higher doping level. Furthermore, the dielectric properties of the NKLNTS ceramics do not show a significant change by Fe₂O₃ doping. However, the addition of Fe₂O₃ was found to have a significant influence on the electric fatigue resistance and the durability against water. The presence of oxygen vacancies caused by the replacement of Fe³⁺ for B-site ions makes the NKLNTS ceramics harder.     

Phase transformation in Sm2O3 at high pressure: In situ synchrotron X-ray diffraction study and ab initio DFT calculation

Sm₂O₃ was compressed at room temperature up to 44.0 GPa and then decompressed back to ambient pressure. In situ X-ray diffraction was used to monitor the structural changes in the sample. A cubic to hexagonal phase transformation was observed in Sm₂O₃ for the first time. After decompression back to ambient pressure, the hexagonal phase was not quenchable and transformed to a monoclinic phase. Ab initio Density- Functional-Theory (DFT) calculations were performed to obtain theoretical data for comparison with the experimental results and elucidation of the transformation mechanism. A possible phase transformation mechanism that is consistent with the experimental results and theoretical calculations is proposed.     

电子束蒸发沉积Ir膜真空紫外反射特性

Ir是一种重要的真空紫外反射材料,在太阳物理、宇宙物理、生命科学、大气物理、同步辐射等方面有着十分重要的应用.对电子束蒸发沉积Ir膜在真空紫外波段的反射特性进行了系统的理论和实验研究.根据吸收材料基底上单层金属膜数学计算模型,对不同基片上各种厚度的Ir膜真空紫外反射率进行了优化计算.根据计算和前期实验结果,采用电子束蒸发方法,在石英、K9玻璃基片上沉积了不同厚度的Ir膜,在入射波长120 nm处获得了近30%正入射反射率,对应的Ir膜厚度为12 nm.过厚或过薄均不利于Ir膜反射率的提高.经退火处理后,Ir膜中张应力有所释放但并未消除,同时晶粒平均尺寸显著增大,反射率下降.     

Kinetics of Liquid Structure Transition of Sn-（40wt%）Bi Melt

The kinetics of temperature-induced liquid-liquid structure transition （TI-LLST） process in Sn-（40wt%）Bi melt is investigated in isothermal and continuous heating experiments with electrical resistivity method. The time evolution pattern of the electrical resistivity suggested the transition mechanism of TI-LLST for Sn-（40wt%）Bi melt in accordance with the autocatalytic reaction model, which is an indication of nucleation-growth type. With the calculated reaction rate constant KT and apparent activation energy Δ E, we deduce the reason for the characteristics of TI-LLST. The present result may be beneficial for further understanding of the nature of TI-LLST.     

多注毫米波行波管收集极的热设计

 为解决多注毫米波行波管收集极的散热问题,保障行波管工作可靠性与稳定性,利用 ANSYS 有限元软件模拟分析了收集极的传热特性,针对性地调整和优化了收集极相关参数与结构。研究结果表明：接触热阻是造成收集极具有较高温升的一个重要因素,由接触热阻所造成的温升约占收集极内外温度差的1/3;并不是第二电极与磁环接触宽度越宽所对应的收集极散热能力就越强,而是在一定工作条件下其散热能力存在极限值;对于绝缘陶瓷材料,应根据绝缘陶瓷的温度特性以及行波管的功率大小来进行选择;翼片式散热器是一种符合设计要求的理想散热结构。     

A coupled IEM/FEM approach for solving elastic problems with multiple cracks

In this paper, the detailed two-dimensional infinite element method (IEM) formulation with infinite element (IE)–finite element (FE) coupling scheme for investigating mode I stress intensity factor in elastic problems with imbedded geometric singularities (e.g. cracks) is presented. The IE–FE coupling algorithm is also successfully extended to solve multiple crack problems. In this method, the domain of the primary problem is subdivided into two sub-domains modeled separately using the IEM for the multiple crack sub-domain, and the FEM for the uncracked sub-domain. In the IE sub-domain, the similarity partition concept together with the IEM formulation are employed to automatically generate a large number of infinitesimal elements, layer by layer, around the tip of each crack. All degrees of freedom related to the IE sub-domain, except for those associated with the coupling interface, are condensed and transformed to form a finite master IE for each crack with master nodes on sub-domain boundary only. All of the stiffness matrices constructed in the IE sub-domains are assembled into the system stiffness matrix for the FE sub-domain. The resultant FE solution with a symmetrical stiffness matrix, having the singularity effect of imbedded cracks in IEs, is required only for solving multiple crack problems.Using these efficient numerical techniques a very fine mesh pattern can be established around each crack tip without increasing the degree of freedom of the global FEM solution. One is easily allowed to conduct parametric analyses for various crack sizes without changing the FE mesh. Numerical examples are presented to show the performance of the proposed method and compared with the corresponding known results where available.     

Boron doping and structure control of carbon materials for supercapacitor application: the effect of freeze-drying and air-drying for porosity engineering

Journal of Solid State Electrochemistry - In the present work, we demonstrate a strategy of combining boron doping and porosity engineering for a highly modulated carbon component and pore...