The technology by which selective materials separates into different fractions via pores or minute gaps depending upon their pore size and the separation driving force is known as membrane separations. They can be classified as: Microfiltration (MF), Ultrafiltration (UF), Ion-Exchange (IE), and Reverse Osmosis (RO). Journal Article is sometimes called a Scientific Article, a Peer-Reviewed Article, or a Scholarly Research Article. Together, journal articles in a particular field are often referred to as The Literature. Journal articles are most often Primary Research Articles. However, they can also be Review Articles.