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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
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If you were a subscriber of “Entrepreneur Success” or “Business Opportunities” in the early 98, it's likely you have noticed Jeff Paul’s catchy ads, depicting him sitting at his kitchen as well as in his underwear talking on the phone and counting money and ads like “How I earn $4000 every day sitting within my home inside my underwear?” Jeff himself declared he makes 1000’s of dollars each day before his lunch! Those catchy, intriquing, notable and funny ads were run continuously for about three years during the early 98. But those ads were suddenly disappeared; Jeff Paul suddenly sunk somewhere in deep marketing competition.
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