TAILIEUCHUNG - Mechanical vacuum pumps *

This study investigated the chemical, physical, and mechanical properties of the bamboo species Phyllostachys pubescens and its utilization potential to manufacture medium density fiberboard (MDF). The result showed holocellulose and alpha-cellulose content increased from the base to the top portion. There was no significant variation in Klason lignin content or ash content from the base to the top portion of the bamboo. The outer layer had the highest holocellulose, alpha cellulose, and Klason lignin contents and the lowest extractive and ash contents. The epidermis had the highest extractive and ash contents and the lowest holocellulose and alpha-cellulose content | Mechanical vacuum pumps . Chew BOC Edwards Crawley United Kingdom Abstract This presentation gives an overview of the technology of contemporary primary and secondary mechanical vacuum pumps. For reference a brief history of vacuum and a summary of important and basic vacuum concepts are first presented. 1 Introduction Vacuum It is just like turning on a tap. We have come to take for granted vacuum and its application in all its degrees from vacuum forming metallurgy integrated circuitry fabrication to space simulation. The current provision the engineering innovations and global availability bear testament to the technical and commercial pioneers of the 19th and 20th centuries. The full history itself can be traced back to the ancient philosophers however here we touch briefly on the revolutionary work of the Natural Philosophers of the period of the Scientific Enlightenment. There is some debate as to who achieved the first deliberate experimental vacuum Berti or Torricelli however it is pretty certain that it was in Italy in the 1640s. The concept of a vacuum or void was a huge discussion amongst philosophical heavyweights across Europe in the 17th century. Indeed in reasoning against a vacuum the Aristotolean horror vacuii the Torricellian void in an inverted mercury column was said to have been filled with elements from the liquid mercury itself. As well as creating a vacuum they also recognised the concept of outgasssing a concept familiar to many practitioners today. Galileo and Descartes were party to the debate be it via the concept of the weight of air measured as g l compared to a modern value of g l . The work spread from Italy Baliani to Mersenne and Pascal in France. It is worth noting that these intellectual endeavours were patronized by the great realms of the time both for application to live issues for example suction of water in mines and also for the reflected glory on the patrons themselves. Science as Natural Philosophy was truly .

• Cơ khí - Chế tạo máy
• Responses in Cereals
• C4 Plants Adaptation
• High Levels
• Drought Environments
• Response Crosstalk
• Reactive Oxygen