Yasuhiro Tamayama

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The five phenylethanoids, acteoside (1), cistanoside F (2), lavandulifolioside (3), plantamajoside (4) and isoacteoside (5) were isolated from the herb of Plantago lanceolata L. (Plantaginaceae). Compounds 1, the major phenylethanoid in the herb of P. lanceolata L., and 4, the major phenylethanoid in the herb of P. asiatica L., showed inhibitory effects on(More)
A new phenylethanoid glycoside, plantasioside, was isolated from the aerial parts of Plantago asiatica. The structure of plantasioside was deduced from chemical and spectral evidence to be 1',2'-[beta(3,4-dihydroxyphenyl)-alpha,beta-dioxoethanol]-6'-O- caffeoyl- O-beta-D-glucopyranoside. In addition, the structure of orobanchoside from P. depressa and P.(More)
We study the no reflection condition for a planar boundary between vacuum and an isotropic chiral medium. In general chiral media, elliptically polarized waves incident at a particular angle satisfy the no reflection condition. When the wave impedance and wavenumber of the chiral medium are equal to the corresponding parameters of vacuum, one of the(More)
In this review, we describe recent developments in functional metamaterials based on coupled resonators. We first consider coupled resonator metamaterials that mimic electromagnetically induced transparency (EIT). We present a circuit model for EIT-like metamaterials and introduce a new coupled resonator in which the coupling is provided by a field gradient(More)
We develop a theory for realizing frequency-independent, reflectionless, single-layer metafilms based on the Brewster effect. A designed metafilm based on the theory is numerically analyzed using a finite-difference time-domain method. The numerical analysis demonstrates that the reflectance of the metafilm vanishes independent of the frequency and that the(More)
The Brewster effect is extended to single-layer metafilms. In contrast to bulk media, the Brewster effect in metafilms can be realized by tailoring the radiation pattern of a distribution of meta-atoms rather than the effective medium parameters. A metafilm composed of bi-anisotropic split-ring resonators is designed based on the theory, and its(More)
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