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991.
利用溶胶凝胶燃烧合成法分别制备了八种重稀土掺杂的硼酸钐粉体,采用XRD和SEM对粉体的物相组成和形貌进行了表征。结果表明,重稀土离子的引入并没有改变SmBO3的晶体结构,SmBO3以三斜相为主,并含有少量的六方相,六方相的含量随着掺杂离子半径的减小而增加。重稀土离子掺杂的SmBO3粉体形貌呈现不规则片状,颗粒尺寸差别不大。采用紫外可见分光光度计对粉体进行了反射率测试,八种粉体在1.064μm处的反射率变化不大,但均较未掺杂SmBO3粉体的反射率略有提高,说明六方相的存在明显降低了SmBO3的光学性能。 相似文献
992.
993.
994.
A series of carbazole cationic compounds based on donor- Π—acceptor (D-Π-A) structure were synthesized and characterized.
They exhibit large two-photon absorption cross sections when excited by a 810 nm a laser beam, and their photophysical properties
show that the intramolecular charge transfer (ICT) character is predominant. Moreover these compounds can easily pass though
the intact cell membrane of living cells, amongst, 3-(1-hydroxyethyl -4-vinylpyridium iodine)-N-butyl carbazole (9B-HVC) has
been proven to be capable of accumulating within the mitochondria possessing large membrane potential and imaging this organelle
in living cells by means of two-photon fluorescence microscopy. At the same time usable fluorescent photos can be obtained
at lower incident excitation power (5 mW) and low-micromolar concentrations (2 μM), which does not result in significant reduction
in cell viability over a period of at least 24 h. 相似文献
995.
In this paper, we present a new preconditioned AOR-type iterative method for solving the linear system Ax=b, where A is a Z-matrix, and prove its convergence. Then we give some comparison theorems to show that the rate of convergence of the preconditioned AOR-type iterative method is faster than the rate of convergence of the AOR-type iterative method. Finally, we give two numerical examples to illustrate our results. 相似文献
996.
In this paper, the authors introduce an enhanced photovoltaic device with nanohole arrays only in its antireflection coating. These nanoholes can improve light trapping efficiency as well as photoelectric conversion efficiency of the device. The authors analyze the light absorption of the devices with nanohole arrays by Finite-Difference Time Domain method and calculate the photoelectric conversion efficiency. The results show that the nanohole arrays can improve the light trapping more efficiently than the Si3N4 antireflection coating, especially, in 400-600 nm spectral range. Nanohole arrays with different characteristic parameters were fabricated in the antireflection coating layer of a Φ200 μm Si detector by using focused-ion beam system. With the optimized nanohole arrays, the enhancements factor of the experimental sample's photoelectric conversion efficiency is ~ 16% within the 400-600 nm spectral range and ~ 10% within the 400-1100 nm spectral range. 相似文献
997.
A design method along with its results, for a space optical system with high resolution and wide field of view, is described. Such optical systems can be used in the infrared as well as visible configurations. The proposed design is based on an on-axis Ritchey-Chrétien system with corrected lens element while the primary mirror is a segmented aperture. Here the on-axis concept allows wide-field enabling a variety of observations designed for the multi-object spectrometer instruments, optimized for low scattering and low emission of light. The use of segmented mirrors in the optical system allows adopting any method for its fabrication purposes. Segment results are discussed and the image quality of the design based on these results is evaluated in this paper. 相似文献
998.
Hydrogen storage material has been much developed recently because of its potential for proton exchange membrane (PEM) fuel cell applications. A successful solid-state reversible storage material should meet the requirements of high storage capacity, suitable thermodynamic properties, and fast adsorption and desorption kinetics. Complex hydrides, including boron hydride and alanate, ammonia borane, metal organic frameworks (MOFs), covalent organic frameworks (COFs) and zeolitic imidazolate frameworks (ZIFs), are remarkable hydrogen storage materials because of their advantages of high energy density and safety. This feature article focuses mainly on the thermodynamics and kinetics of these hydrogen storage materials in the past few years. 相似文献
999.
S. H. Ma Z. Y. Jiao X. Q. Dai Z. X. Yang 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(4):437-443
Ordered sulphur overlayers adsorbed on Ir(100) surface are studied with differentcoverage ranging from 0.11 to 1.0 ML. Calculations indicate that atomic S adsorbsfavourably in hollow sites, forming strong covalent bonds with the substrate surface andthe adsorption energy is nearly unchanged at lower coverages(θ S ≤ 0.50 ML). In good agreement withexperimental observations, the p(2 × 2)-S and c(2 × 2)-Sare predicted to be the most stable overlayers. The obtained surface electronic structuremodifications induced by sulphur adsorption are coverage-dependent and the results are inaccordance with the rectangular band and the Hammer-Nørskov models. Moreover, the effectof sulphur on the adsorption of CO is discussed in the p(2 × 2)?(S + CO)overlayer on Ir(100). 相似文献
1000.
C. Wang H. Q. Ma R. Z. Jiao Y. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):573-578
This article indicates an improved protocol of quantum repeaters through the scheme of nest entanglement purification [Phys. Rev. Lett. 81, 5932 (1998)]. The hyperentangled photon pairs are utilized to overcome the limitations of long distance quantum communication via noisy channels. In addition, it is mentioned that if there are imperfect quantum operations and noises in realistic communication, the fidelities of hyperentangled quantum channels will be improved compared with the traditional entangled states. 相似文献