Asphalt driveways are typically less expensive than concrete, costing a minimum of about $2.50 per square foot. An asphalt driveway might last just 20 years; however, while a concrete driveway can last more than 30.
Semipermeable membrane. The diffusion of water through a selectively permeable membrane is called osmosis.This allows only certain particles to go through including water and leaving behind the solutes including salt and other contaminants. In the process of reverse osmosis, thin film composite membranes (TFC or TFM) are used.
Facilitated Diffusion Diffusion is the flow of chemicals and other substances to a region of low concentration from a region of high concentration. Certain small nonpolar substances, such as oxygen, can diffuse directly through the membrane in a process called simple diffusion. Large, polar or charged molecules and ions either cannot squeeze through the small membrane spaces or are repelled by the hydrophobic membrane interior.