Cell encapsulation unit) and N-acetyl-D-glucosamine (acetylated unit). It is derived from the N-deacetylation of chitin and has been used for several applications such as drug delivery, space-filling implants and in wound dressings. However, one drawback of this polymer is its weak mechanical properties and is thus often combined with other polymers such collagen to form a polymer with stronger mechanical properties for cell encapsulation applications. Agarose is a polysaccharide derived from seaweed used for nanoencapsulation of cells and the cell/agarose suspension can be modified to form microbeads by reducing the temperature during preparation. However, one drawback with the microbeads so obtained is
History of the petroleum industry Arabia due to its crude reserves derived from bitumen. History of the petroleum industry The petroleum industry is not of recent origin, but petroleum's current status as the key component of politics, society, and technology has its roots in the early 20th century. The invention of the internal combustion engine was the major influence in the rise in the importance of petroleum. According to Herodotus, more than four thousand years ago natural asphalt was employed in the construction of the walls and towers of Babylon, great quantities of it were found on the banks of the river Issus, one of