Over the past several decades, nearly half of Japan's public research and development budget has been spent in Tsukuba. Important scientific breakthroughs by its researchers include the identification and specification of the molecular structure of superconducting materials, the development of organic optical films that alter their electrical conductivity in response to changing light, and the creation of extreme low-pressure vacuum chambers. Tsukuba has become one of the world's key sites for government-industry collaborations in basic research. Earthquake safety, environmental degradation, studies of roadways, fermentation science, microbiology, and plant genetics are some of the broad research topics having close public-private partnerships.