Glossary - F

foam

Foam is a gas in a liquid colloidal system.

Surfactants play an important role in their manufacture and their subsequent stability. Surfactants are used to enhance the stability of desired foams and also used to break down (degrade) unwanted foams e.g. the foams formed in effluent streams.

first law of thermodynamics

see: thermodynamics.

floating point

This is a particular way of representing numbers on computers similar to the scientific notation for writing numbers (e.g. 0.31415 x 10¹ also written as 0.31415E1 by computers where `E1' means `x 10¹'). It is almost universally used to represent numbers that are not integers (0,1,2..). Operations such as addition, multiplication and division using these number are usually the most time consuming parts of scientific computations and the number of such operations that can be performed each second is used as a (crude) measure of computer performance. See FLOPS.

FLOPS

Stands for `Floating-point operations per second' (see Floating Point). This is the usual measure of the number of arithmetic operations that a computer can perform per second. It usuall refers to addition and subtractions which are the fastest operations. Multiplication and especially division may be significantly slower (less FLOPS). See also MFLOPS, GFLOPS, TFLOPS.

fluid

Liquids and gasses are fluid, they can flow. Fuild is used in a more general context for things which can flow or have no fixed structure. See for example, fluid membrane.

fluid membrane

A membrane where the structure is not fixed. Cell membranes are fluid membranes.

freeze-fracturing

Freeze-fracturing is a technique developed in the 1960s whereby a sample is frozen, typically with liquid nitrogen, and then struck with a knife to break (fracture) it. The exposed surfaces can then be examined with an electron microscope. In places where the sample fractures along the interior of a plasma membrane it is possible to see where the large protein molecules are.