In this paper we propose a new design for an ultra-wideband microwave metamaterial absorber. This metamaterial absorber has a sandwich structure, and the top metal pattern is periodically arranged on the copper background. This metamaterial absorber is combined with Fe–Co composites and metamaterials, which solves the narrow-band problem of microwave absorption. We realize an absorptivity of more than 90% in the 2.16–18 GHz frequency band for normal incidence. The thickness of the structure is 0.61 mm (about 1/48.8 wavelength at the central frequency). The performance of the proposed absorber is not sensitive to the polarization of incident waves.

HIRRV is a fish rhabdovirus that is considered as an important pathogen threatening the fish farming industry represented by flounder because of its high infectivity and fatality rate. To date, research toward understanding the complex pathogenic mechanism of HIRRV is still in its infancy and faces many challenges.

We propose a nonlinear fluid model to describe the dust void formation in a magnetic field environment. It is found that the radius of the dust void keeps decreasing as the intensity of the magnetic field increases. Further research shows that the circular motion of ions affects the balance of electric field force and ion-drag force, which is the main reason for the change of dust voids. The Lorentz force of grains theoretically tends to increase the radius of the dust void, but the force is so small that it can be ignored.