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311.
Parthasarathy R Bykhovski A Gelmont B Globus T Swami N Woolard D 《Physical review letters》2007,98(15):153906
In this work, a theoretical study of the coupling of TM polarized subterahertz (THz) radiation with periodic semiconductor rectangular slot arrays was conducted, using InSb as an example. Simulation results showed that the structure with 4-12 microm thickness provides over a 20-30-fold increase in the electric field at slot edges in a nanosize region ( approximately 500 nm). The enhancement of the THz electromagnetic field extends across the slots and reaches peak values at the edges due to discontinuity effects. Because of the strong local electromagnetic field enhancement, the structure can potentially be used for the development of novel biophotonic sensors, leading to improved detection sensitivity. 相似文献
312.
Optical gap solitons, which exist due to a balance of nonlinearity and dispersion due to a Bragg grating, can couple to acoustic waves through electrostriction. This gives rise to a new species of "gap-acoustic" solitons (GASs), for which we find exact analytic solutions. The GAS consists of an optical pulse similar to the optical gap soliton, dressed by an accompanying phonon pulse. Close to the speed of sound, the phonon component is large. In subsonic (supersonic) solitons, the phonon pulse is a positive (negative) density variation. Coupling to the acoustic field damps the solitons' oscillatory instability, and gives rise to a distinct instability for supersonic solitons, which may make the GAS decelerate and change direction, ultimately making the soliton subsonic. 相似文献
313.
Synthesis of Carbon/Sulfur Nanolaminates by Electrochemical Extraction of Titanium from Ti2SC
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Dr. Meng‐Qiang Zhao Morgane Sedran Zheng Ling Maria R. Lukatskaya Olha Mashtalir Michael Ghidiu Boris Dyatkin Darin J. Tallman Prof. Thierry Djenizian Prof. Michel W. Barsoum Prof. Yury Gogotsi 《Angewandte Chemie (International ed. in English)》2015,54(16):4810-4814
Herein we electrochemically and selectively extract Ti from the MAX phase Ti2SC to form carbon/sulfur (C/S) nanolaminates at room temperature. The products are composed of multi‐layers of C/S flakes, with predominantly amorphous and some graphene‐like structures. Covalent bonding between C and S is observed in the nanolaminates, which render the latter promising candidates as electrode materials for Li‐S batteries. We also show that it is possible to extract Ti from other MAX phases, such as Ti3AlC2 , Ti3SnC2 , and Ti2GeC, suggesting that electrochemical etching can be a powerful method to selectively extract the “M” elements from the MAX phases, to produce “AX” layered structures, that cannot be made otherwise. The latter hold promise for a variety of applications, such as energy storage, catalysis, etc. 相似文献
314.
Inside Back Cover: Designed Enclosure Enables Guest Binding Within the 4200 Å3 Cavity of a Self‐Assembled Cube (Angew. Chem. Int. Ed. 19/2015)
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315.
Dr. Zhuhua Zhang Yang Yang Guoying Gao Prof. Boris I. Yakobson 《Angewandte Chemie (International ed. in English)》2015,54(44):13022-13026
Two‐dimensional (2D) materials, such as graphene and boron nitride, have specific lattice structures independent of external conditions. In contrast, the structure of 2D boron sensitively depends on metal substrate, as we show herein using the cluster expansion method and a newly developed surface structure‐search method, both based on first‐principles calculations. The preferred 2D boron on weaker interacting Au is nonplanar with significant buckling and numerous polymorphs as in vacuum, whereas on more reactive Ag, Cu, and Ni, the polymorphic energy degeneracy is lifted and a particular planar structure is found to be most stable. We also show that a layer composed of icosahedral B12 is unfavorable on Cu and Ni but unexpectedly becomes a possible minimum on Au and Ag. The substrate‐dependent 2D boron choices originate from a competition between the strain energy of buckling and chemical energy of electronic hybridization between boron and metal. 相似文献
316.
Influence of Solution Volume on the Dissolution Rate of Silicon Dioxide in Hydrofluoric Acid
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Boris Shvartsev Danny Gelman Ilia Komissarov Alon Epshtein Dr. David Starosvetsky Prof. Yair Ein‐Eli 《Chemphyschem》2015,16(2):370-376
Experimental data and modeling of the dissolution of various Si/SiO2 thermal coatings in different volumes of hydrofluoric acid (HF) are reported. The rates of SiO2‐film dissolution, measured by means of various electrochemical techniques, and alteration in HF activity depend on the thickness of the film coating. Despite the small volumes (0.6–1.2 mL) of the HF solution, an effect of SiO2‐coating thickness on the dissolution rate was detected. To explain alterations detected in HF activity after SiO2 dissolution, spectroscopic analyses (NMR and FTIR) of the chemical composition of the solutions were conducted. This is associated with a modification in the chemical composition of the HF solution, which results in either the formation of an oxidized species in solution or the precipitation of dissolution products. HF2? accumulation in the HF solution, owing to SiO2 dissolution was identified as the source of the chemical alteration. 相似文献
317.
The Synthesis of New Organoselenium Heterocyclic Compounds: 2‐aryl‐4‐phenyl‐5,6,7,8‐tetrahydro‐4H‐selenochromenes
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Dmitriy Yurievich Direnko Yaroslav Borisovich Drevko Boris Ivanovich Drevko 《中国化学会会志》2015,62(12):1068-1071
We have explored the reactions of 2‐(3‐oxo‐1‐aryl‐3‐phenylpropyl)cyclohexanone ( 1–3 ) with hydrogen selenide in situ in conditions of acid catalysis, and synthesized new 2‐aryl‐4‐phenyl‐5,6,7,8‐tetrahydro‐4H‐selenochromenes ( 4–6 ). 相似文献
318.
319.
We consider inverse potential scattering problems where the source of the incident waves is located on a smooth closed surface outside of the inhomogeneity of the media. The scattered waves are measured on the same surface at a fixed value of the energy. We show that these data determine the bounded potential uniquely. 相似文献
320.
Jai Rajyaguru Mario E. Villanueva Boris Houska Benoît Chachuat 《Journal of Global Optimization》2017,68(2):413-438
This article presents an arithmetic for the computation of Chebyshev models for factorable functions and an analysis of their convergence properties. Similar to Taylor models, Chebyshev models consist of a pair of a multivariate polynomial approximating the factorable function and an interval remainder term bounding the actual gap with this polynomial approximant. Propagation rules and local convergence bounds are established for the addition, multiplication and composition operations with Chebyshev models. The global convergence of this arithmetic as the polynomial expansion order increases is also discussed. A generic implementation of Chebyshev model arithmetic is available in the library MC++. It is shown through several numerical case studies that Chebyshev models provide tighter bounds than their Taylor model counterparts, but this comes at the price of extra computational burden. 相似文献