Reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma.

This paper describes the fabrication and characterization of a reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma. The silicon reflector, composed of serially connected p-i-n diodes, forms a highly dense solid-state plasma by injecting electrons and holes into the intrinsic region. When this plasma silicon reflector is turned on, the front-realized gain of the antenna increases by more than 2 dBi beyond 5.3 GHz. To achieve the large gain increment, the structure of the antenna is carefully designed with the aid of semiconductor device simulation and antenna simulation. By using an aluminum nitride (AlN) substrate with high thermal conductivity, self-heating effects from the high forward current in the p-i-n diode are efficiently suppressed. By comparing the antenna simulation data and the measurement data, we estimated the conductivity of the plasma silicon reflector in the on-state to be between 104 and 105 S/m. With these figures, silicon material with its technology is an attractive tunable material for a reconfigurable antenna, which has attracted substantial interest from many areas, such as internet of things (IoT) applications, wireless network security, cognitive radio, and mobile and satellite communications as well as from multiple-input-multiple-output (MIMO) systems.

Porcine epidemic diarrhea virus infection: inhibition by polysaccharide from Ginkgo biloba exocarp and mode of its action.

Porcine epidemic diarrhea virus (PEDV) is the predominant cause of severe entero-pathogenic diarrhea in swine. Until now there is no recorded clinically effective antiviral chemotherapeutic agent for treatment of diseases caused by PEDV. This study aimed to investigate in vitro anti-PEDV effect of polysaccharide from Ginkgo biloba exocarp and mode of its action. The polysaccharide exhibited potent antiviral activity against PEDV reducing the formation of a visible CPE [a 50% inhibitory concentration (IC50)=1.7±1.3µg/mL], compared to positive control, ribavirin and it did not show cytotoxicity at 100µg/mL [a 50% cytotoxicity concentration (CC50)=100µg/mL]. Polysaccharide also showed effective inhibitory effects when added at the viral attachment and entry steps. Moreover, polysaccharide effectively inactivated PEDV infection in time-, dose- and temperature-dependent manners. Overall, this research revealed that polysaccharide could inhibit PEDV infection, and that polysaccharide may be involved in PEDV-Vero cell interactions, as the virus attachment and entry to the Vero cells was hindered by the polysaccharide. Therefore, polysaccharide possessing effective inhibitory effect on viral attachment and entry steps of PEDV life cycle is a good candidate for development of antivirals.