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671.
Michael Augustine Sunny Mathew Vincent Mathew 《International Journal of Infrared and Millimeter Waves》2008,29(5):534-544
This paper studies electromagnetic wave propagation in hybrid structures consisting of ferrite and superconducting films.
Dispersion relations for transverse electric mode of propagation are derived. Numerical results are presented for two specific
structures viz. a ferrite/superconductor structure and a ferrite/superconductor/ferrite structure and dependence of propagation
on various structural parameters and frequency are determined. The non-reciprocal nature of propagation is also established. 相似文献
672.
Stereoselective synthesis of highly functionalized tetrahydrofurans via the 1,3-dipolar cycloaddition reaction of acyclic carbonyl ylides to activated alkenes is described. 相似文献
673.
One of the difficulties in analyzing eigenvalue problems that arise in connection with integrable systems is that they are
frequently non-self-adjoint, making it difficult to determine where the spectrum lies. In this paper, we consider the problem
of locating and counting the discrete eigenvalues associated with the Faddeev-Takhtajan eigenvalue problem, for which the
sine-Gordon equation is the isospectral flow. In particular we show that for potentials having either zero topological charge
or topological charge ± 1, and satisfying certain monotonicity conditions, the point spectrum lies on the unit circle and
is simple. Furthermore, we give an exact count of the number of eigenvalues. This result is an analog of that of Klaus and
Shaw for the Zakharov-Shabat eigenvalue problem. We also relate our results, as well as those of Klaus and Shaw, to the Krein
stability theory for J-unitary matrices. In particular we show that the eigenvalue problem associated to the sine-Gordon equation has a J-unitary structure, and under the above conditions the point eigenvalues have a definite Krein signature, and are thus simple
and lie on the unit circle. 相似文献
674.
Hema Tresa Varghese C. Yohannan Panicker V.S. Madhavan Samuel Mathew Jarmila Vinsova Christian Van Alsenoy 《Journal of Raman spectroscopy : JRS》2009,40(9):1211-1223
FT‐IR and FT‐Raman spectra of 4‐chloro‐2‐(4‐bromophenylcarbamoyl)phenyl acetate were recorded and analyzed. The vibrational wavenumbers and corresponding vibrational assignments were examined theoretically using the Gaussian03 set of quantum chemistry codes. The red shift of the NH stretching wavenumber in the infrared (IR) spectrum from the computed wavenumber indicates the weakening of the NH bond resulting in proton transfer to the neighbouring oxygen atom. The simultaneous IR and Raman activations of the CO stretching mode give the charge transfer interaction through a π‐conjugated path. Optimized geometrical parameters of the title compound are in agreement with similar reported structures. From the optimized structure, it is clear that the hydrogen bonding decreases the double bond character of CO bond and increases the double bond character of the C N bonds. The first hyperpolarizability, predicted infrared intensities and Raman activities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non‐linear optics. The assignments of the normal modes are done by potential energy distribution (PED) calculations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
675.
Mathew D. Anker Martyn P. Coles 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(38):13586-13589
We report the anion [Al(NONAr)(Se)]? (NONAr=[O(SiMe2NAr)2]2?, Ar=2,6‐iPr2C6H3), which is an isoelectronic Group 13 metal analogue of the carbonyl group containing an aluminium–selenium multiple bond. It was synthesized in a single step from the reaction of the aluminyl anion [Al(NONAr)]? with elemental selenium. Spectroscopic, crystallographic, and computational analysis confirmed multiple bonding between aluminium and selenium. Addition of a second equivalent of selenium afforded the diselenirane, [Al(NONAr)(κ2‐Se2)]?, which is an isoelectronic analogue of the dioxirane group. 相似文献
676.
Effect of post thermal annealing on the structural and optical properties of ZnO thin films prepared from polymer precursor 下载免费PDF全文
ZnO thin films were synthesised by a new method which uses polyvinyl alcohol (PVA) as polymer precursor. The films are annealed at different temperatures and for different annealing times. The structural parameters, like grain size, lattice constants, optical band gap, and Urbach energy, depend on the annealing temperature and annealing time. All the films possess tensile strain which relaxes as the annealing temperature and the annealing time increases. The photoluminescence (PL) spectra contain only ultraviolet (UV) peaks at low temperature, but as the annealing temperature and time increase we observe peaks at blue and green regions with variation of the intensities of these peaks with annealing temperature and annealing time. 相似文献
677.
Hunan Yi Ahmed Iraqi Mathew Stevenson Claire J. Elliott David G. Lidzey 《Macromolecular rapid communications》2007,28(10):1155-1160
Attachment of triarylamino‐functional groups at the 9‐position of 2,7‐linked carbazole polymers results in blue‐emitting materials with two independent redox processes that were attributed to the triarylamino groups and the polymer backbone, respectively. This new class of blue‐emitting conjugated polymers was prepared via a Suzuki cross‐coupling reaction and showed low turn‐on voltages in electroluminescent devices as a result of their low ionisation potentials. The photophysical, electrochemical and electroluminescent properties of these materials are discussed.
678.
Supported liquid membrane (SLM) has been used as a sample preparation method in the simultaneous extraction of a mixture of three stilbene compounds in cow's milk, urine, bovine kidney and liver tissues matrices. The stilbene compounds analysed included, dienestrol, diethylstilbestrol and hexestrol. The liquid membrane used for trapping these compounds consisted of 5% tri-n-octylphosphine oxide (TOPO) dissolved in di-n-hexylether/n-undecane (1:1). The extraction efficiencies obtained after enrichment of 1 ng/L stilbenes in variety of biological matrices of milk, urine, liver, kidney and water, ranged from 60 - 70%, 71 - 86%, 69 - 80%, 63 - 7A% and 72 - 93% respectively. The detection limits obtained from urine extraction were 2.1 ng/L, 1.3 ng/L and 3.0 ng/L; from liver and kidney tissues were 2.9 ng/L, 1.6 ng/L and 3.8 ng/L and from milk was 3.2 ng/L, 2.5 ng/L and 4.3 ng/L for hexestrol, dienestrol and diethylstilbestrol respectively. 相似文献
679.
680.
Mathew A. Johnson Pascal Noble L. Miguel Rodrigues Kevin Zumbrun 《Archive for Rational Mechanics and Analysis》2013,207(2):693-715
Extending results of Johnson and Zumbrun showing stability under localized (L 1) perturbations, we show that spectral stability implies nonlinear modulational stability of periodic traveling-wave solutions of reaction diffusion systems under small perturbations consisting of a nonlocalized modulation plus a localized perturbation. The main new ingredient is a detailed analysis of linear behavior under modulational data ${\bar{u}^{\prime}(x)h_{0}(x)}$ , where ${\bar{u}}$ is the background profile and h 0 is the initial modulation. 相似文献