We find a sufficient condition for the existence of surface (Rayleigh) waves based on the Rayleigh-Ritz variational method.
When specialized to a homogeneous half-space, the sufficient condition recovers the known criterion for the existence of subsonic
surface waves. A simple existence criterion in terms of material properties is obtained for periodic half-spaces of general
anisotropic materials. Further, we numerically compute the dispersion relation of the surface waves for a half-space of periodic
laminates of two materials and demonstrate the existence of surface wave band gaps. 相似文献
Antimony trichloride is an efficient catalyst for the cyclization of 2-amino chalcones to the corresponding 2-aryl-2,3-dihydroquinolin-4(1H)-ones under mild reaction conditions and in almost quantitative yields. 相似文献
CO2 and steam/CO2 electroreduction to CO and methane in solid oxide electrolytic cells (SOEC) has gained major attention in the past few years. This work evaluates, for the very first time, the performance of two different ZnO–Ag cathodes: one where ZnO nanopowder was mixed with Ag powder for preparing the cathode ink (ZnOmix–Ag cathode) and the other one where Ag cathode was infiltrated with a zinc nitrate solution (ZnOinf –Ag cathode). ZnOmix–Ag cathode had a better distribution of ZnO particles throughout the cathode, resulting in almost double CO generation while electrolysing both dry CO2 and H2/CO2 (4:1 v/v). A maximum overall CO2 conversion of 48% (in H2/CO2) at 1.7 V and 700 °C clearly indicated that as low as 5 wt% zinc loading is capable of CO2 electroreduction. It was further revealed that for ZnOinf –Ag cathode, most of CO generation took place through RWGS reaction, but for ZnOmix–Ag cathode, it was the synergistic effect of both RWGS reaction and CO2 electrolysis. Although ZnOinf –Ag cathode produced trace amount of methane at higher voltages, with ZnOmix–Ag cathode, there was absolutely no methane. This seems to be due to strong electronic interaction between Zn and Ag that might have suppressed the catalytic activity of the cathode towards methanation.
Experimental Mechanics - The DIC Challenge 2.0 follows on from the work accomplished in the first Digital Image Correlation (DIC) Challenge Reu et al. (Experimental Mechanics 58(7):1067, 1). The... 相似文献
Quantum correlations provide dramatic advantage over the corresponding classical resources in several communication tasks. However, a broad class of probabilistic theories exists that attributes greater success than quantum theory in many of these tasks by allowing supra-quantum correlations in “space-like” and/or “time-like” paradigms. In this letter, a communication task involving three spatially separated parties is proposed where one party (verifier) aims to verify whether the bit strings possessed by the other two parties (terminals) are equal or not. This task is called authentication with limited communication, the restrictions on communication being: i) the terminals cannot communicate with each other, but (ii) each of them can communicate with the verifier through single use of channels with limited capacity. Manifestly, classical resources are not sufficient for perfect success of this task. Moreover, it is also not possible to perform this task with certainty in several nonclassical theories although they might possess stronger “space-like” and/or “time-like” correlations. Surprisingly, quantum resources can achieve the perfect winning strategy. The proposed task thus stands apart from all previously known communication tasks as it exhibits quantum advantage over other nonclassical strategies. 相似文献
We present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy. 相似文献
Radio wave operating in millimetrewave and microwave frequency bands are adversely affected due to rain. Particularly the attenuation is of immense significance for sensitive remote measurements by satellites using frequencies greater than 10 GHz. Maintenance of an uninterrupted communication link requires a precise knowledge of the attenuation effect due to rain for commissioning right kind of transmitting sources for various purposes required in present day situation. Precise measurement of attenuation at various frequencies will enable us to choose the right frequency, polarization, incident angle and power of the source for different purposes. In this paper we have compared the results of earlier works using aRb Olsen et al, (1) and the formulation by Moupfouma, (2) on the basis of theoretical analysis for explaining the observed results. Effect of temperature, considered in detail in this communication, has contributed the necessary correction factor of the rain attenuation for explaining the observed results. Theoretical analyses to measure the attenuation of the propagating wave due to temperature variation in the rain path have been presented. Correction factor due to temperature profile (temperature from the ground to the rain height within which the radio wave traces its path) has been incorporated in two models by using the concept of dipole energy changes. The effect of this temperature is noted to be quite significant and incorporates an error to the extent of 7–8%. 相似文献
An explicit form of a colour-singlet Fermion field is constructed from the operator solution of SU(n) Thirring model where the quark-fields are known to be confined in LSZ sense. In simple cases of massless quarks these ferions are free with zero mass and can be expressed as the antisymmetric composites of constituent quark fields. This simple exercise suggests an alternative to conventional two-dimensional QCD which seems to confine all Fermion including baryons by Schwinger mechanism. 相似文献
Ternary and quaternary fission produced in silver and bromine nuclei have been studied withK5 nuclear emulsion exposed to 1.8 GeV/cK− beams. The frequency of the ternary events is found to be ∼0.08 of that of the binary events produced in the same volume
of the emulsion. The range ratio and range distribution of the fission fragments are studied and the angles between each pair
of the fragments are determined. Ranges are found to vary from 5 to 40μ with a maximum number lying between 5 and 10μ. The angles between the fission fragments are found to form a broad distribution extending from 40° to 180°. A few of the
events have also been analysed to give them a possible identity. A possible case of quaternary fission has also been reported.
This paper was presented at the Symposium on 3rd High Energy Physics held at Bhubaneswar during November 1976. 相似文献