Abstract: The present disclosure is related to a microwave source. The microwave source may include a cathode heater and a thermionic emitter. The cathode heater may include a first component, and a second component enclosing at least a portion of the first component. The thermionic emitter may be configured to release electrons when the thermionic emitter is heated by the cathode heater. At least a portion of the second component of the cathode heater may be in contact with the thermionic emitter.

Abstract: The-use of magnesium hydride in the preparation of a composition for preventing and treating chronic periodontitis, and a magnesium hydride toothpaste are provided. In the composition or the magnesium hydride toothpaste, magnesium hydride has a weight percentage of 1% to 3%. The toothpaste has the functions of disinfection, anti-inflammation, anti-oxidation, removing tooth stains, improving bad breath, alleviating gingival swelling, bleeding, and recession, and improving periodontitis symptoms. An appropriate amount of magnesium hydride fine particles is added in toothpaste, and the magnesium hydride particles can be hydrolyzed into hydrogen and magnesium ions with anti-inflammatory effects, which can also inhibit alveolar bone resorption. The magnesium hydride-containing composition is safe in use, and can effectively prevent the occurrence and development of periodontal diseases after long-term use.