23 research outputs found
Plane-wave scattering by self-complementary metasurfaces in terms of electromagnetic duality and Babinet's principle
We investigate theoretically electromagnetic plane-wave scattering by
self-complementary metasurfaces. By using Babinet's principle extended to
metasurfaces with resistive elements, we show that the frequency-independent
transmission and reflection are realized for normal incidence of a circularly
polarized plane wave onto a self-complementary metasurface, even if there is
diffraction. Next, we consider two special classes of self-complementary
metasurfaces. We show that self-complementary metasurfaces with rotational
symmetry can act as coherent perfect absorbers, and those with translational
symmetry compatible with their self-complementarity can split the incident
power equally, even for oblique incidences
Frequency-Independent Response of Self-Complementary Checkerboard Screens
This research resolves a long-standing problem on the electromagnetic
response of self-complementary metallic screens with checkerboardlike geometry.
Although Babinet's principle implies that they show a frequency-independent
response, this unusual characteristic has not been observed yet due to the
singularities of the metallic point contacts in the checkerboard geometry. We
overcome this difficulty by replacing the point contacts with resistive sheets.
The proposed structure is prepared and characterized by terahertz time-domain
spectroscopy. It is experimentally confirmed that the resistive checkerboard
structures exhibit a flat transmission spectrum over 0.1--1.1 THz. It is also
demonstrated that self-complementarity can eliminate even the
frequency-dependent transmission characteristics of resonant metamaterials.Comment: 6 pages, 5 figures + Supplemental Material (6 pages, 7 figures
Broadband and energy-concentrating terahertz coherent perfect absorber based on a self-complementary metasurface
We demonstrate that a self-complementary checkerboard-like metasurface works
as a broadband coherent perfect absorber (CPA) when symmetrically illuminated
by two counter-propagating incident waves. A theoretical analysis based on wave
interference and results of numerical simulations of the proposed metasurface
are provided. In addition, we experimentally demonstrate the proposed CPA in
the terahertz regime by using a time-domain spectroscopy technique. We observe
that the metasurface can work as a CPA below its lowest diffraction frequency.
The size of the absorptive areas of the proposed CPA can be much smaller than
the incident wavelength. Unlike conventional CPAs, the presented one
simultaneously achieves the broadband operation and energy concentration of
electromagnetic waves at the deep-subwavelength scale.Comment: 5 pages, 4 figure
NOR-3, a donor of nitric oxide, increases intracellular Zn²⁺ concentration and decreases cellular thiol content: A model experiment using rat thymocytes, FluoZin-3, and 5-chloromethylfluorescein
Our previous study showed that nitroprusside, a donor of nitric oxide (NO), increased intracellular Zn2+ concentration without affecting cellular content of glutathione (GSH) although it has been proposed that the cytotoxicity of NO is resulted from its interaction with glutathione and zinc. Nitroprusside releases not only NO but also cyanides (Fe(II)CN and Fe(III)CN), CN-, Fe2+, and Fe3+. Therefore, such decomposition products may mask NO-induced action on cellular GSH content. In this study, we used NOR-3 as a donor of NO to reveal the effects of NO on intracellular Zn2+ concentration and cellular GSH content in a cytometric manner with fluorescent probes, FluoZin-3-AM and 5-chloromethylfluorescein diacetate. NOR-3 at 1-3 mM significantly increased intracellular Zn2+ concentration and decreased cellular GSH content. After the removal of extracellular Zn2+ by diethylenetriamine-N,N,N',N",N"-pentaacetic acid (DTPA, a chelator for Zn2+), the increase in intracellular Zn2+ concentration by NOR-3 was still observed although DTPA significantly attenuated the increase in intracellular Zn2+ concentration by NOR-3. Results suggest an involvement of both intracellular Zn2+ release and increase in membrane Zn2+ permeability. It is likely that NO induces oxidative stress, leading to an increase in intracellular Zn2+ concentration
経頚静脈的管肝内門脈大循環短絡術による portal hypertensive gastropathy の変化
金沢大学医学系研究科荻野, 英
Theoretical study on dynamical planar-chirality switching in checkerboard-like metasurfaces
In this paper, we show that the handedness of a planar chiral checkerboard-like metasurface can be dynamically switched by modulating the local sheet impedance of the metasurface structure. We propose a metasurface design to realize the handedness switching and theoretically analyze its electromagnetic characteristic based on Babinet’s principle. Numerical simulations of the proposed metasurface are performed to validate the theoretical analysis. It is demonstrated that the polarity of asymmetric transmission for circularly polarized waves, which is determined by the planar chirality of the metasurface, is inverted by switching the sheet impedance at the interconnection points of the checkerboard-like structure. The physical origin of the asymmetric transmission is also discussed in terms of the surface current and charge distributions on the metasurface