Probiotics such as bifidobacteria are typically used in cases when a disease occurs or might occur due to a kill-off of normal bacteria. For example, treatment with antibiotics can destroy disease-causing bacteria, but also normal bacteria in the GI (gastrointestinal) and urinary tracts.
The 3-place Hiller Model 360, military H-23 Raven, was based on the U.S. Navy UH-12, which was first flown in 1948. The H-23 Raven performed as a utility, observation, and MedEvac helicopter during the Korean war.
  1896 The helicopter was first invented in 1907.   1900 The firs â¦ t helicopter was made in 1939 be Igor Sikorsky the model was a VS-300. Experimental helicopters existed in the 1920s. The first unit designated practical military helicopters used in combat was the Korean War (1950-53).rench inventor, Etienne Oehmichen built and flew a helicopter one kilometer in 1924. Another early helicopter that flew for a decent distance was the German Focke-Wulf Fw 61, invented by an unknown inventor.