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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
To own one of these vintages defines what you are, how we hang around and the way you wish to be known, and Cubans will go to incredible lengths to keep their classic cars running. 1950's bumpers and tailpipes are recreated and myriad the rest are adapted. Steering wheels carved from wood, hub cabs made from aluminum cans and plastic sheets for windows are typical. While such shortcuts could be frowned upon in the United States, classic car lovers admire the Cubans' ingenuity and their ability to maintain the cars running.
Nevertheless in case you have failed to do this for quite a while you'd probably come to be in all probability now struggling the consequences and still have just a few extra pounds than you when had, then you could do something and begin obeying the golden rules of eating healthy and exercising to get back in form
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