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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
The development of modern society has made the division of labor more and more fine. The era of individual fighting alone has become a thing of the past, and more and more need collective cooperation. The ability of individual to be strong again, work to do again outstanding, also cannot leave the team this big atmosphere. Therefore, team members can only grow together with mutual trust, initiative and sharing. Trust is a critical step for the whole team to work together. If the team members don't have enough trust in each other, it will be difficult to communicate with each other, and they will lose the foundation of each other's cooperation, and the whole team will be separated from the sand and have no strength to speak of
2. If diarrhea, abdominal distension, loss of appetite and other symptoms occur, it is important to be mindful of the light diet and adequate nutrition.
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