Look on the hoses and gaskets to find from where the fluid could be leaking. Add power steering stop leak additive to your power steering fluid. Lucas Power Steering Stop Additive is 100 percent guaranteed to stop seal leaks. In older cars, the seals shrink, causing leaks.
Diffusion is the net movement of molecules or atoms from a region of high concentration with high chemical potential to a region of low concentration with low chemical potential.
Facilitated Diffusion goes with, or down, the concentration gradient. The type of transport that goes against the gradient is active transport. Facilitated diffusion is different from regular diffusion in that it is facilitated or helped by proteins along the cell membrane (if you were talking in that context).