Losev, who devoted his career to the study of crystal detectors. In 1922 working at the new Nizhny Novgorod Radio Laboratory he discovered negative resistance in biased zincite (zinc oxide) point contact junctions. He realized that amplifying crystals could be an alternative to the fragile, expensive, energy-wasting vacuum tube. He used biased negative resistance crystal junctions to build solid-state amplifiers, oscillators, and amplifying and regenerative radio receivers, 25 years before the invention of the transistor. Later he even built a superheterodyne receiver. However his achievements were overlooked because of the success of vacuum tubes. His technology was dubbed "Crystodyne" by science publisher Hugo Gernsback one of the few people in the West who paid attention to it. After ten years he abandoned research into this technology and it was forgotten. The negative resistance diode was rediscovered with the invention of the tunnel diode in 1957, for which Leo Esaki won the 1973 Nobel Prize in Physics. Today, negative resistance diodes such as the Gunn diode and IMPATT diode are widely used as microwave oscillators in such devices as radar speed guns and garage door openers. Discovery of the light emitting diode (LED) In 1907 British Marconi engineer Henry Joseph Round noticed that when direct current was passed through a silicon carbide (carborundum) point contact junction, a spot of greenish, bluish, or yellowish light was given off at the contact point. Round had constructed a light emitting diode (LED). However he just published a brief two paragraph note about it and did no further research. While investigating crystal detectors in the mid-1920s at Nizhny Novgorod, Oleg Losev independently discovered that biased carborundum and zincite junctions emitted light. Losev was the first to analyze this device, investigate the source of the light, propose a theory of how it worked, and envision practical applications. He published his experiments in 1927 in a Russian journal, and the 16 papers he published on LEDs between 1924 and 1930 constitute a comprehensive study of this device. Losev did extensive research into the mechanism of light emission. He measured rates of evaporation of benzine from the crystal surface and found it was not accelerated when light was emitted, concluding that the luminescence was a "cold" light not caused by thermal effects. He theorized correctly that the explanation of the light emission was in the new science of quantum mechanics, speculating that it was the inverse of the