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The rapid development of air filters is closely related to the development of military industry and electronic industry. In the first world war, the use of various chemical agents, asbestos fibre filter paper as the smoke filter layer of military gas masks came into being. The glass fiber filter medium is used in air filtration to obtain a patent in the United States in October 1940. In the 1950s, the United States studied the production process of glass fiber filter paper, and the air filter was improved and developed. In the 1960s, HEPA filters came out; In the 1970s, the filter paper of fine glass fiber was used as the HEPA filter of filter medium, and the filtration efficiency of particle size of 013 micron particle diameter was 99.9998%. Since the eighty s, with the emergence of new test method, use evaluation to improve and to improve the filtering performance requirements, found the HEPA filter there is a serious problem, and he had a higher ULPA filter performance. Countries are still working on it and expect more advanced air filters soon
Volkswagen's Chairman, Ferdinand Piech, has previously expressed curiosity about purchasing Ducati last 2008. It appears his desire has become an actuality and can mark the 12th brand inside Volkswagen make. This purchase will give Ferdinand the opportunity to finally own the company that makes some of the finest most effective bikes. Ferdinand, who he himself owns one of these fine superbikes, notes until this deal really should have happened 30 years ago and he is finally getting another shot advertising online. In fact, Piech once told Reuters that he was only enthusiastic about Ducati, even though on offer the rival Italian motorcycle company MV Agusta.
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