F

Ferroelectrics

Crystalline substances that have a permanent spontaneous electric polarization (electric dipole moment per cubic centimeter) that can be reversed by an electric field.

Ferrofluid

A fluid in which fine particles of iron, magnetite or cobalt are suspended, typically in an oil. A ferrofluid is superparamagnetic and can create liquid seals held in position by magnetic fields. One application of ferrofluids is to keep dust off of the drive shafts of magnetic disk drives. Ferrofluids were invented by NASA as a way to control the flow of liquid fuels in space.

Ferromagnetic materials

Substances, including a number of crystalline materials, that are characterized by a possible permanent magnetization.

Ferromagnetism

A phenomenon by which a material can exhibit spontaneous magnetization. One of the strongest forms of magnetism, ferromagnetism is responsible for most of the magnetic behavior encountered in everyday life and is the basis for all permanent magnets.

Field effect

The local change from the normal value produced by an electric field in the charge-carrier concentration of a semiconductor.

Field emission

The emission of electrons from the surface of a metallic conductor into a vacuum (or into an insulator) under influence of a strong electric field. In field emission, electrons penetrate through the potential surface barrier by virtue of the quantum-mechanical tunnel effect. Also known as cold emission. See also electron tunneling.

Fluorescence

The process in which molecules or matter absorb high energy photons and then emit lower energy photons. The difference in energy causes molecular vibrations.

Fluorescence spectroscopy

A technique to measure the interaction of radiant energy with matter by passing emitted fluorescent light through a monochromator to record the fluorescence emission spectrum.

Fluorescent probe

A stain used for tagging and labeling biological cells to detect structures, molecules, or proteins within the cell. Also single-stranded pieces of DNA, with enzymatically incorporated fluorescent tags, affixed in a microscopic array (DNA microarray).

Fuel cell

An electrical cell that converts the intrinsic chemical free energy of a fuel into direct-current electrical energy in a continuous catalytic process. Fuel cells extract the chemical energy bound in fuel and, in combination with air as an oxidant, transform it into electricity. Researchers are hoping to develop fuel cells that could take the place of combustion engines, thereby reducing the world dependence on fossil fuels.

Fullerene

A molecular form of pure carbon that takes the form of a hollow cage-like structure with pentagonal and hexagonal faces. The most abundant form of fullerenes is C60 (carbon-60), a naturally occurring form of carbon with 60 carbon atoms arranged in a spherical structure that allows each of the molecule's 60 atomic corners to bond with other molecules. Larger fullerenes may contain from 70 to 500 carbon atoms. Named for R. Buckminster Fuller for his writing on geodesic domes; also referred to as “buckyballs.”

G

Gas-phase reactions

A class of chemical reactions that occur in a single gaseous phase based on the physical state of the substances present. Examples include the combination of common household gas and oxygen to produce a flame.

Gene expression

The transcription, translation, and phenotypic manifestation of a gene.

Gene sequencing

Technology used to interpret the sequence of the nucleotides (adenine, cytosine, guanine, and thymine) in a DNA sample from bands on an X-ray film image. Scientists use a combination of lasers, high-precision optics, and computer software to determine the sequence of fluorescently tagged DNA molecules.

Gene technology

Techniques that allow experimenters to manipulate specific genes within an organism and determine the effect this has on the functioning of the organism.

Genomics

The study of the genetic content of organisms.

Green chemistry

The use of chemical products and processes that reduce or eliminate substances hazardous to human health or the environment, creating no waste or generating only benign waste.

H

Heterogeneous catalysis

A chemical process in which the catalyst and the reactant are present in separate phases. Usually the catalyst is a solid, the reactants and products are in gaseous or liquid phases, and the catalytic reaction occurs on the surface of the solid.

High Throughput Screening (HTS)

An assortment of technologies used to identify small molecules. HTS is often used in drug development to screen potential sources for novel molecules. It is capable of processing a wide variety of input samples and track data for each.

Homogeneous catalysis

A process in which a catalyst is in the same phase — usually a gas or liquid — as the reactant. Catalysis of the transformation of organic molecules by acids or bases is one of the most widespread types of homogeneous catalysis.

Hydrogen bonding

The interaction of a hydrogen atom with another atom, influencing the physical properties and three-dimensional structure of a chemical substance. Hydrogen bonding generally occurs between atoms of hydrogen and nitrogen, oxygen, or fluorine. An important example of a hydrogen bonding is the formation of the DNA double helix.

Hydrophilic effect

Having an affinity for, attracting, adsorbing, or absorbing water. Hydrophilic effect occurs when a liquid comes in contact with another phase — typically a solid substrate, if it attracts the liquid molecules — causing the liquid to attain a relatively large contact area with the substrate.

Hydrophobic effect

Lacking an affinity for, repelling, or failing to adsorb or absorb water. Hydrophobic effect occurs when a liquid comes in contact with another phase — typically a solid substrate, if it exerts a repulsive force onto the liquid — causing the liquid to retract from the surface, with relatively little contact area between liquid and substrate.

I

Infrared (IR) spectroscopy

A technique in which infrared light is passed through matter and some of the light is absorbed by inciting molecular vibration. The difference between the incident and the emitted radiation reveals structural and functional data about the molecule.

Ion channel

A protein-coated pore in a cell membrane that selectively regulates the diffusion of ions into and out of the cell, allowing only certain ion species to pass through the membrane.

Ion conductors

The discharge of charged particles in a fluid electrolyte to conduct an electrical current.