N

Nanocharacterization

The understanding of the chemical and physical properties of atomic and nanoscale materials.

Nanocomposites

Materials that result from the intimate mixture of two or more nanophase materials. See composite.

Nanocrystalline materials

Solids with small domains of crystallinity within the amorphous phase. Applications include optical electronics and solar cells.

Nanoelectromechanical Systems (NEMS)

A generic term to describe nanoscale electrical/mechanical devices.

Nanofiber

A polymer membrane formed by electrospinning, with filament diameters of 150–200 nanometers. Also called nanomesh, it is used in air and liquid filtration applications.

Nanofluidics

The control of nanoscale amounts of fluids.

Nanolithography

Writing nanoscale patterns. See Lithography.

Nanomanipulation

The process of manipulating items at an atomic or molecular scale in order to produce precise structures.

Nanomaterials

Nanoscale particles, films, and composites designed and assembled in controlled ways.

Nanometer

A unit of measurement equal to one-billionth of one meter. The head of a pin is about 1 million nanometers across. A human hair is about 60,000 nanometers in diameter, and a DNA molecule is between 2-12 nanometers wide.

Nanoparticles

Particles ranging from 1 to 100 nanometers in diameter. Semiconductor nanoparticles up to 20 nanometers in diameter are often called quantum dots, nanocrystals, or Q-particles.

Nanoporous materials

Engineered materials with nanoscale holes, used in filters, sensors, and diffraction gratings. In DNA sequencing, nanoporous materials have tiny holes that allow DNA to pass through one strand at a time. In biology, complex protein assemblies that span cell membranes allow ionic transport across the otherwise impermeable lipid bilayer.

Nanoshell

A nanoparticle that has a metallic shell surrounding a semiconductor. Nanoshells are being investigated for use in treating cancer.

Nanostructures

Structures made from nanomaterials.

Nanotubes

Long, thin cylinders of carbon, discovered in 1991 by S. Iijima. These large macromolecules are unique for their size, shape, and remarkable physical properties. They can be thought of as a sheet of graphite (a hexagonal lattice of carbon) rolled into a cylinder. The physical properties are still being discovered. Nanotubes have a very broad range of electronic, thermal, and structural properties that change depending on the different kinds of nanotube (defined by its diameter, length, and chirality, or twist). To make things more interesting, besides having a single cylindrical wall (Single Walled Nanotubes or SWNTs), nanotubes can have multiple walls (MWNTs)--cylinders inside the other cylinders. Usually referred to as carbon nanotubes, also known as nanorods. Applications for carbon nanotubes include high-density data storage, nanoscale electronics, and flexible solar cells.

NMR (Nuclear Magnetic Resonance) pectroscopy

Analytical technique used to determine the structure of molecules. In NMR, the molecule is placed within a strong magnetic field to align the atomic nuclei. An oscillating electromagnetic field is applied, and the radiation absorbed or emitted by the molecule is measured. Not all atoms can be detected using NMR because the nuclei must have non-zero magnetic moments.

Noncovalent interactions

Interactions first recognized by J. D. van der Waals in the nineteenth century. In contrast to the covalent interactions, noncovalent interactions are weak interactions that bind together different kinds of building blocks into supramolecular entities. Also referred to as van der Waals interactions.

O

Oxidation

Process in which a molecule loses one or more electrons to another component of the reaction.

P

Phase

A part of a sample of matter that is in contact with other parts but is separate from them. Properties within a phase are homogeneous (uniform). For example, oil and vinegar salad dressing contains two phases: an oil-rich liquid, and a vinegar-rich liquid. Shaking the bottle breaks the phases up into tiny droplets, but there are still two distinct phases.

Phase diagram

A map that shows which phases of a sample are most stable for a given set of conditions. Phases are depicted as regions on the map; the borderlines between regions correspond to conditions where the phases can coexist in equilibrium.

Phase transport

The movement of heat, mass, and momentum in a medium.

Photoluminescence

Light excited in a body by some form of electromagnetic radiation in the ultraviolet, visible, or infrared regions of the electromagnetic spectrum. See electroluminescence, LED, and luminescence.

 

Piezoelectrics

Dielectric crystal that produce a voltage when subjected to mechanical stress or can change shape when subjected to a voltage.

 

Polymer

A macromolecule formed from a long chain of molecules called monomers; a high-molecular-weight material composed of repeating sub-units. Polymers may be organic, inorganic, or organometallic, and synthetic or natural in origin. See biopolymer.

 

Polymerase chain reaction

A technique for copying and amplifying the complementary strands of a target DNA molecule.

 

Polymorphism

The property of a chemical substance crystallizing into two or more forms having different structures, such as diamond, graphite, and fullerenes from carbon. Also known as pleomorphism.

 

Protein

Large organic molecules involved in all aspects of cell structure and function.

 

Proteomics

The separation, identification, and characterization of the complete set of proteins present in the various cells of an organism; the design and construction of new proteins.

 

Q

Quantum confinement effect

Atoms caged inside nanocrystals.

 

Quantum dot

A nanoscale crystalline structure made from cadmium selenide that absorbs white light and then re-emits it a couple of nanoseconds later in a specific color. The quantum dot was originally investigated for possible computer applications. Recently, researchers are investigating the use of quantum dots for medical applications, using the molecule-sized crystals as probes to track antibodies, viruses, proteins, or DNA within the human body.

R

Raman spectroscopy

Analysis of the intensity of Raman scattering, in which light is scattered as it passes through a material medium and suffers a change in frequency and a random alteration in phase. The resulting information is useful for determining molecular structure.

Reduction

In analytical chemistry, the preparation of one or more subsamples from a sample of material that is to be analyzed chemically. In chemistry, reduction refers to the reaction of hydrogen with another substance or the chemical reaction in which an element gains an electron.

 

Resists

Elements used in performing photolithography experiments. Resists are polymer materials spun onto a substrate. When exposed to UV light, the polymer in the resist cross-links. When treated with a solvent, the cross-linked portion of the resist dissolves, leaving the desired pattern.

 

RNA (ribonucleic acid)

A long linear polymer of nucleotides found mainly in the cytoplasm of a cell that transmits genetic information from DNA to the cytoplasm and controls certain chemical processes in the cell.

 

RNA structures

Molecules that act as scaffolds upon which proteins are assembled to form functional ribosomes. RNA structures include a variety of single-stranded and double-stranded structures that result in complex three-dimensional structures.