Abstract: The present disclosure belongs to the technical field of biological products for veterinary medicine, and specifically relates to a recombinant foot-and-mouth disease virus (FMDV) with a reduced immunosuppressive activity, a preparation method and use thereof, and a recombinant vaccine strain. According to the present disclosure, it is firstly discovered that FMDV 3B protein has an immunosuppressive function, and key sites for exerting the immunosuppressive function are found. A recombinant FMDV vaccine strain with a lost immunosuppressive function in FMDV 3B protein is constructed by introducing amino acid mutations into three repeated copies of FMDV 3B protein.

Abstract: A method and device for controlling a flight of an unmanned aerial vehicle (UAV) is provided. The UAV includes a fuselage, two wings, two supporting arms, two rotor wing structures, two second power modules, two third power modules, two steering modules, a lifting module, an altitude sensor, and a speed sensor. The two wings are fixed to the fuselage, the supporting arms are fixed to the wings, the rotor wing structure includes a first power module and a driving module, the driving module of the rotor wing structure is fixed to the supporting arm, and the driving module is configured to drive the first power module to rotate such that the first power module switches between the level flight mode and the lifting mode.

Abstract: A method and an apparatus for protecting an unmanned aerial vehicle and an unmanned aerial vehicle are provided. After a positioning system of the unmanned aerial vehicle fails, a flight speed of the unmanned aerial vehicle is acquired at a time point before the positioning system fails, and then a flight state of the unmanned aerial vehicle is determined according to the flight speed, where the flight state includes a low-speed flight state and a high-speed flight state; and then a flight protection strategy of the unmanned aerial vehicle is adjusted according to the flight state. By implementing the method, after the positioning system of the unmanned aerial vehicle is in failure, explosion probability of the unmanned aerial vehicle can be reduced, and flight safety of the unmanned aerial vehicle can be improved.

Abstract: Embodiments of the present invention relate to an unmanned aerial vehicle protection method and apparatus and an unmanned aerial vehicle. The method includes: switching the unmanned aerial vehicle to an attitude mode after a positioning system of the unmanned aerial vehicle fails; controlling the unmanned aerial vehicle in the attitude mode and reducing a height of the unmanned aerial vehicle; and controlling the unmanned aerial vehicle to land safely when obtained ground environment information meets a preset landing condition. By adopting the foregoing method, the unmanned aerial vehicle can safely and smoothly land on the ground after a positioning sensor of the unmanned aerial vehicle fails, thereby reducing the probability of explosion of the unmanned aerial vehicle and improving the flight safety of the unmanned aerial vehicle.

Abstract: The embodiments is an unmanned aerial vehicle. The unmanned aerial vehicle includes: an airframe; and a fixed-wing assembly and a rotor assembly, both replaceably connected to the airframe. The fixed-wing assembly is connected to the airframe to form a vertical take-off and landing fixed-wing unmanned aerial vehicle and the rotor assembly is connected to the airframe to form a multi-rotor unmanned aerial vehicle, thereby implementing an unmanned aerial vehicle that can switch between the vertical take-off and landing fixed-wing unmanned aerial vehicle and the multi-rotor unmanned aerial vehicle.

Abstract: Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten alkali metal and the electrode comprising the combined alkali/non-alkali metals.

Abstract: Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten alkali metal and the electrode comprising the combined alkali/non-alkali metals.

Abstract: Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

Abstract: Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.