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81.
Orthogonally branched single-crystalline magnesium oxide nanostructures were synthesized through a simple chemical vapor transport and condensation process in a flowing Ar/O(2) atmosphere. Other morphologies, such as cubes and nanowires, can also be obtained under different controlled conditions. The formation of different types of nanostructures can be tuned by modifying oxygen partial pressure during the synthesis. All the nanostructures are cubic single-crystalline enclosed by low-index {100} facets. Growth mechanisms for the nanostructures are discussed in detail: different supersaturation ratios, relatively high substrate temperatures, and surface defects in certain crystallographic planes cooperatively take important effects on determining the product morphologies. Structural defect-related blue light emission of the three types of MgO nanostructures was investigated. The MgO nanostructures with abundant morphologies may find applications in various nanodevices, and the kinetics-driven methodology might be exploited to synthesize similar nanostructures of other functional oxide materials. 相似文献
82.
83.
Phenyl-1,2,3-triazoles containing (E)-vinyl halide were readily synthesized via a one-pot, three-component reaction of 3-(4- or 2-azidophenyl)acrylic acid, NXS(X=Cl, Br and I) and 1-alkynes in MeCN-H2O (9:1 v/v) catalyzed by LiOAc/CuI–sodium ascorbate system.
84.
从G倾斜功率谱和倾斜跟踪残余误差两个方面分析了大气湍流外尺度对倾斜跟踪系统跟踪精度的影响。详细推导了G倾斜功率谱以及倾斜跟踪残差与大气湍流外尺度的函数关系式。数值计算结果表明大气湍流外尺度对G倾斜功率谱以及倾斜跟踪残余误差的低频段影响较大,而对高频段的影响可以忽略不计。 相似文献
85.
86.
In a radial shearing interferometer, a portion of the test beam is magnified and used as the reference for the tested wavefront. However, the reference portion is always off center (lateral shear), which complicates the wavefront reconstruction. A modal method for solving this problem is presented here. This method uses orthogonal Zernike polynomials and its matrix formalism to calculate the Zernike coefficient of the wavefront under test. This approach has easier implementation, is better filtering, and has a more adaptive practical situation. The corresponding mathematical formula is deduced, and a computer simulation is also made to verify operation of the algorithm. The result of simulation analysis shows that the proposed method is correct and accurate. 相似文献
87.
Binary Level Set Methods for Dynamic Reservoir Characterization by Operator Splitting Scheme 下载免费PDF全文
Changhui Yao 《advances in applied mathematics and mechanics.》2012,4(6):780-798
In this paper, operator splitting scheme for dynamic reservoir
characterization by binary level set method is employed.
For this problem, the absolute permeability of the two-phase
porous medium flow can be simulated by the constrained augmented
Lagrangian optimization method with well data and seismic
time-lapse data. By transforming the constrained optimization
problem in an unconstrained one, the
saddle point problem can be solved by Uzawas algorithms
with operator splitting scheme, which is based on the essence
of binary level set method. Both the simple and complicated
numerical examples demonstrate that the given algorithms are
stable and efficient and the absolute permeability can be
satisfactorily recovered. 相似文献
88.
89.
研究了硫脲和硫代硫酸钠体系中ZnS∶Cu 纳米微粒的光致发光性能随Cu+ 离子掺杂浓度及生长时间的变化. 在325nm 的紫外光激发下, ZnS∶Cu 纳米微粒产生位于500~540nm 的宽带发射, Cu+ 掺杂浓度为0.6% 时发射达到最强. 该发射峰随掺杂浓度的提高和微粒生长时间的延长而红移; 当Cu+ 掺杂浓度为0.2% 时, ZnS∶Cu 纳米微粒还产生一个位于450nm 的蓝色发射带, 该发射在掺杂浓度更高时被猝灭. 硫脲和硫代硫酸钠体系中ZnS∶Cu 的发光性质较为相似, 但后者的发射强度明显高于前者. 相似文献
90.
本文研究了7-安替吡啉偶氮-8-羟基喹啉-5-磺酸(AQS)与钪(Ⅲ)的显色反应。在高酸度下该试剂与钪(Ⅲ)所成配合物具有较好的选择性,其最大吸收波长在490nm处,摩尔吸光系数为1.37×104 L·ctn-1·mol-1,Sc2O3含量在2.5μg~40μg/25mL范围内符合比尔定律。100倍的镧和30倍的 相似文献