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41.
Hatem Samaali Fehmi Najar Slim Choura Ali H. Nayfeh Mohamed Masmoudi 《Nonlinear dynamics》2011,63(4):719-734
In this paper, we propose the design of an ohmic contact RF microswitch with low voltage actuation, where the upper and lower
microplates are displaceable. We develop a mathematical model for the RF microswitch made up of two electrostatically actuated
microplates; each microplate is attached to the end of a microcantilever. We assume that the microbeams are flexible and that
the microplates are rigid. The electrostatic force applied between the two microplates is a nonlinear function of the displacements
and applied voltage. We formulate and solve the static and eigenvalue problems associated with the proposed microsystem. We
also examine the dynamic behavior of the microswitch by calculating the limit-cycle solutions. We discretize the equations
of motion by considering the first few dominant modes in the microsystem dynamics. We show that only two modes are sufficient
to accurately simulate the response of the microsystem under DC and harmonic AC voltages. We demonstrate that the resulting
static pull-in voltage and switching time are reduced by 30 and 45%, respectively, as compared to those of a single microbeam-microplate
RF-microswitch. Finally, we investigate the global stability of the microswitch using different excitation conditions. 相似文献
42.
Azouzi S Morandat S El Kirat K 《Langmuir : the ACS journal of surfaces and colloids》2011,27(15):9465-9472
Cyclosporin A (CsA) is a hydrophobic peptide drug produced by the fungus Tolypocladium inflatum. CsA is commonly used as an immunosuppressive drug, but it also has antimalarial activity. The immunosuppressive activity of CsA is clearly due to its association with specific proteins of immune cells such as cyclophilins. By contrast, the antimalarial properties of this peptide are completely independent of the association with a parasite's cyclophilins. Because of its hydrophobicity, CsA may interact with biological membranes, which may participate in its therapeutic effect. Recently, we have shown a marked preference of CsA for insertion into sphingomyelin (SM) monolayers. In this article, we measure for the first time the ability of CsA to induce permeabilization and aggregation and to change the lipid order, especially in the presence of SM. Calcein-release experiments permitted us to show that CsA causes the leakage of the fluorescent probe from SM-rich liposomes by 40% and PC liposomes by 11%, suggesting a lipid-selective effect. Electron microscopy and dynamic light scattering experiments confirmed the different interaction of CsA with SM and PC vesicles: it formed much larger aggregates with SM than with PC. Our results taken together suggest that CsA could specifically weaken and aggregate SM-rich membranes, which could in turn explain why CsA is efficient in the treatment of malaria. Indeed, CsA could inhibit the development of Plasmodium by permeabilizing and aggregating the SM-rich membrane network formed by the parasite during its intraerythrocytic growth cycle. 相似文献
43.
Existence of a ground state and scattering for a nonlinear Schrödinger equation with critical growth
Takafumi Akahori Slim Ibrahim Hiroaki Kikuchi Hayato Nawa 《Selecta Mathematica, New Series》2013,19(2):545-609
We study the energy-critical focusing nonlinear Schrödinger equation with an energy-subcritical perturbation. We show the existence of a ground state in the four or higher dimensions. Moreover, we give a sufficient and necessary condition for a solution to scatter, in the spirit of Kenig and Merle (Invent Math 166:645–675, 2006). 相似文献
44.
45.
We study the cycle structure of words in several random permutations. We assume that the permutations are independent and that their distribution is conjugation invariant, with a good control on their short cycles. If, after successive cyclic simplifications, the word still contains at least two different letters, then we get a universal limiting joint law for short cycles for the word in these permutations. These results can be seen as an extension of our previous work (Kammoun and Maïda. Electron. Commun. Probab. 2020;25:1-14.) from the product of permutations to any non-trivial word in the permutations and also as an extension of the results of Nica (Random Struct. Algorithms1994;5:703-730.) from uniform permutations to general conjugation invariant random permutations. In particular, we get optimal assumptions in the case of the commutator of two such random permutations. 相似文献
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48.
Synthesis of graphitic ordered macroporous carbon with a three-dimensional interconnected pore structure for electrochemical applications 总被引:4,自引:0,他引:4
Su F Zhao XS Wang Y Zeng J Zhou Z Lee JY 《The journal of physical chemistry. B》2005,109(43):20200-20206
In this study, ordered macroporous carbon with a three-dimensional (3D) interconnected pore structure and a graphitic pore wall was prepared by chemical vapor deposition (CVD) of benzene using inverse silica opal as the template. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectrometry, nitrogen adsorption, and thermogravimetric analysis techniques were used to characterize the carbon samples. The electrochemical properties of the carbon materials as a carbon-based anode for lithium-ion batteries and as a Pt catalyst support for room-temperature methanol electrochemical oxidation were examined. It was observed that the CVD method is a simple route to fabrication of desired carbon nanostructures, affording a carbon with graphitic pore walls and uniform pores. The graphitic nature of the carbon enhances the rate performance and cyclability in lithium-ion batteries. The specific capacity was found to be further improved when SnO(2) nanoparticles were supported on the carbon. The specific activity of Pt catalyst supported on the carbon materials for room-temperature methanol electrochemical oxidation was observed to be higher than that of a commercial Pt catalyst (E-TEK). 相似文献
49.
50.
Marwa Abbes Slim Salhi Lénaïg Lefevre Christelle Delaite Rachid El Gharbi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(1):56-63
A series of polyesteramides (PEAs) differing in their amide/ester ratio, within a range of molar composition from 90/10 to 10/90, have been synthesized by a direct melt polycondensation of 1,4-butanediol, adipic acid and β-alanine. Their structure was fully characterized by FTIR and NMR spectroscopy. The resulting copolymers are amorphous, they are thermally stable to temperatures up to 330°C, and present increasing glass transition temperatures at increasing amide content. 相似文献