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排序方式: 共有1354条查询结果,搜索用时 136 毫秒
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Karen S. Torosyan Alexey S. Sedegov Kirill V. Kuskov Mohammad Abedi Dmitry I. Arkhipov Philipp V. Kiryukhantsev-Korneev Stepan Vorotilo Dmitry O. Moskovskikh Alexander S. Mukasyan 《Journal of the American Ceramic Society》2020,103(1):520-530
The influence of different SPS-based methods, that is, conventional spark plasma sintering (SPS), flash SPS (FSPS), and reactive SPS (RSPS) on the properties of Al2O3/SiC composite was investigated. It was shown that the application of preliminary high energy ball milling of the powders significantly enhances the sinterability of the ceramics. It was also demonstrated that FSPS provides unique conditions for rapid, that is, less than a minute, consolidation of refractory ceramics. The Al2O3-20 wt% SiC composite produced by FSPS possesses the highest relative density (~99%), fracture toughness (7.5 MPa m1/2), hardness (20.3 GPa) and wear resistance among all ceramics produced by other SPS-based approaches with dwelling time 10 minutes. The RSPS ceramics hold the highest Young's modulus (390 GPa). Substitution of micron-sized Al2O3 particles by nano alumina does not lead to measurable enhancement of the mechanical properties. 相似文献
64.
Chitosan-based fiber-sponge materials as a promising tool for microalgae harvesting from Lake Baikal
Timofei E. Grigoriev Ksenia I. Lukanina Pavel M. Gotovtsev Kirill V. Gorin Anna A. Melnikova Christina G. Antipova Roman Kamyshinsky Sergei N. Chvalun 《应用聚合物科学杂志》2020,137(40):49209
Mass eutrophication of microalgae and cyanobacteria is observed in Lake Baikal in the past decade. In this paper, the concept of replaceable adsorption filter material based on chitosan flocculant filler and chlorinated polyvinyl chloride polymer nonwoven material are proposed. Functional and mechanical properties and morphology of the material are investigated depending on a packing density and a degree of chitosan filling. The introduction of 45% chitosan increases the Young's modulus up to 10 times, and it makes the material more rigid in 2.8 times. The high efficiency of sorption and growth inhibition of cumulative biomass culture was shown. The biomass source is taken from the coast of Barguzinsky Bay of Lake Baikal. Dominant species is microalgae of Scenedesmus genus. 相似文献
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Quanlong Yang Sergey Kruk Yuehong Xu Qingwei Wang Yogesh Kumar Srivastava Kirill Koshelev Ivan Kravchenko Ranjan Singh Jiaguang Han Yuri Kivshar Ilya Shadrivov 《Advanced functional materials》2020,30(4)
All‐dielectric metasurfaces have become a new paradigm for flat optics as they allow flexible engineering of the electromagnetic space of propagating waves. Such metasurfaces are usually composed of individual subwavelength elements embedded into a host medium or placed on a substrate, which often diminishes the quality of the resonances. The substrate imposes limitations on the metasurface functionalities, especially for infrared and terahertz frequencies. Here a novel concept of membrane Huygens' metasurfaces is introduced. The metasurfaces feature an inverted design, and they consist of arrays of holes made in a thin membrane of high‐index dielectric material, with the response governed by the electric and magnetic Mie resonances excited within dielectric domains of the membrane. Highly efficient transmission combined with the 2π phase coverage in the freestanding membranes is demonstrated. Several functional metadevices for wavefront control are designed, including beam deflector, a lens, and an axicon. Such membrane metasurfaces provide novel opportunities for efficient large‐area metadevices, whose advanced functionality is defined by structuring rather than by chemical composition. 相似文献
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D. A. Vinokurov V. V. Vasilyeva V. A. Kapitonov A. V. Lyutetskiy D. N. Nikolaev N. A. Pikhtin S. O. Slipchenko A. L. Stankevich V. V. Shamakhov N. V. Fetisova I. S. Tarasov 《Semiconductors》2010,44(2):233-237
The effect of the active region thickness on the basic characteristics of high-power semiconductor lasers based on AlGaAs/GaAs/InGaAs asymmetric separate-confinement heterostructures grown by MOCVD epitaxy has been studied. It is shown that the threshold current, temperature sensitivity of the threshold current density, internal quantum efficiency of stimulated emission, and differential quantum efficiency are improved as the active region thickness increases. It is demonstrated that the maximum attainable optical emission power of a semiconductor laser and the internal quantum efficiency of photoluminescence are the most sensitive to defect formation in the heterostructure and become lower as the critical thickness of the strained InxGa1–x As layer in the active region is exceeded. 相似文献
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V. I. Kozlovsky V. S. Krivobok P. I. Kuznetsov S. N. Nikolaev E. E. Onistchenko A. A. Pruchkina A. G. Timiryazev S. I. Chentsov 《Semiconductors》2016,50(1):8-15
A technology for the production of fully hybrid microcavities on the basis of Zn(S)Se films and amorphous insulating SiO2/Ta2O5 coatings is proposed. The influence of all stages of the manufacturing cycle on the structure of exciton states in the Zn(S)Se films is demonstrated. This influence is reduced to four main effects: the appearance of a fine structure of emission lines related to free excitons; a decrease in the relative contribution of excitons bound at neutral acceptors to the exciton-emission spectrum; a shift of the emission lines related to exciton–impurity complexes and free excitons to lower frequencies; and a decrease in the splitting between emission lines related to heavy and light excitons. Samples of fully hybrid microcavities, in which the high structural and optical quality of Zn(S)Se films is retained, are fabricated. 相似文献
70.
Alexander Nikolaev 《Review of Communication》2014,14(3-4):229-244
This paper uses a formal content analysis to decide what moral argument looks like in political debate. Does it involve more the abstract arguments and general principles of the philosophers or the devices of the rhetoricians, like ideographs, casuistry, and moral vocabulary? To test this question, we examine the U.S. debate over intervention in Bosnia between 1991 and 1995 as it showed up in the opinion pages of The New York Times, Christian Science Monitor, and The Washington Post.A major, unexpected finding of the research is support for Appiah's (2010) argument against the New Intuitionists in psychology that outside the laboratory, the major moral work to be done is framing. 相似文献