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Allen’s Rule — a biological rule proposed by Joel Asaph Allen in 1877. It states that warm blooded animals from colder climates usually have shorter limbs than the equivalent animals from warmer climates to help conserve heat.

Allotropes — they are distinct forms of the same element. Allotropes have different chemical and physical properties; for example, graphite and diamond are allotropes of carbon, where connections between pairs of carbon atoms are not all identical among the allotropes.

Atomic force microscope (AFM) — a type of scanning probe microscope. Being a microscope, it can image objects smaller than can be seen by the unaided eye—in fact, much smaller: as small as an atom. It does not use light or any other electromagnetic energy to get an image, nor does it use electrons. The AFM is a mechanical instrument that is used to image and manipulate matter on the nanometer scale.

Bergmann’s Rule — a rule proposed by Christian Bergmann in 1847; it asserts that within a species the body mass of mammals and birds increases with latitude and colder climate, or that within closely related species that differ only in relation to size that one would expect the larger species to be found at the higher latitude.

Bonds (chemical) — a strong attraction between two or more atoms. Bonds hold atoms in molecules and crystals together. There are many types of chemical bonds, but all involve electrons which are either shared or transferred among the bonded atoms.

Brownian motion — the random, incessant movement of very fine particles suspended in liquid or gas; the motion is caused by unbalanced impacts of molecules on the particle. It was discovered by English botanist Robert Brown (in 1827) and appeared as a proof of chaotic molecular motion.

Buckminsterfullerene (buckyball or fullerene) — a form of carbon consisting of 60 carbon atoms bound together to make a roughly spherical “buckyball,” which looks rather like a soccer ball.

Capillaries — one of the minute blood vessels that connect arterioles and venules. These blood vessels form an intricate network throughout the body for the interchange of various substances, such as oxygen and carbon dioxide, between blood and tissue cells.

Caramelization — the oxidation of sugar, a process used extensively in cooking for the resulting nutty flavor and brown color. As the process occurs, chemicals are released producing the characteristic caramel flavor. However, unlike the Maillard reaction (see definition below), caramelization is about oxidation, as opposed to reaction with amino acids.

Carbonization — the conversion of an organic substance into carbon or a carbon-containing residue by heating it strongly in absence of oxygen. Fossil fuels, in general, are the products of the carbonization of vegetable matter.

Carbyne—one of the carbon allotropes that has the chemical structure –(C;C)n–.Carbon in this modification is linear and is a polymer with alternating single and triple bonds.

Conductivity (electrical) — a measure of how easily an electric current, flow of electrons, can pass through a material.

Covalent bond — a covalent bond is a very strong attraction between two atoms that are sharing their electrons. If the atoms share more than two electrons, double and triple bonds are formed, because each shared pair produces its own bond. By sharing their electrons, both atoms are able to achieve a highly stable electron configuration corresponding to that of an inert gas. Covalent bonds are of particular importance in organic chemistry because of the ability of the carbon atom to form four covalent bonds, with its four outermost electrons. These bonds are oriented in definite directions in space, giving rise to the complex geometry of organic molecules.

Cross-linked polymer — a network of polymer chains that are linked by covalent chemical bonds; each polymer is a large molecule (macromolecule) composed of repeating structural units. Cross-links are formed by chemical reactions that are initiated by heat and/or pressure, or by the addition of specific chemicals called crosslinking reagents.

Diamond bond — every carbon atom in diamond has four (single) covalent bonds in a tetrahedral arrangement. In contrast, both buckyball and graphite bonds have two bonds, commonly called double bonds, to one neighboring carbon and two single bonds to two other neighboring carbons, forming 5- and 6-carbon planar rings.

Dimensionality — a measure of spatial extent, especially width, height, or length. For nanoscale objects, it is critical to specify which of the object’s spatial dimensions are in the nanometer scale. For example, a nanotube or a nanofiber would be a 1D nano-object because one of its dimensions (length) is much larger than the other two; similarly, a graphene sheet that is large in two dimensions relative to the third dimension would be a 2D nano-object.

Equilibrium — state of balance; when a body or a system is in equilibrium, there is no net tendency to change. Chemical equilibrium refers to reversible chemical reactions in which the reactions involved are occurring in opposite directions at equal rates, so that no net change is observed.

Graphene — the name given to a single layer of carbon atoms that consists exclusively of hexagonal cells. It is essentially an atom-thick sheet of graphite and is widely used to describe properties of many carbon-based materials, including graphite, large fullerenes, nanotubes, etc. Carbon nanotubes are usually thought of as graphene sheets rolled up into nanometer-sized cylinders.

Homeothermic — (Greek: “homoios” = similar, “therm” = heat); thermoregulation that maintains a constant internal body temperature that is largely independent of the temperature of its surroundings. This temperature is often higher than the immediate environment. A large proportion of the creatures traditionally called “warm-blooded” (mammals and birds) fit this category. The energy required to maintain the homeothermic temperature comes from food—this results in homeothermic animals needing to eat proportionally more food than poikilothermic (cold-blooded) animals.

Hydrogen fuel cell — a device that uses hydrogen and oxygen to create electricity by an electrochemical process, with water and heat as byproducts. The most common type of hydrogen fuel cell is the PEM (Polymer Electrolyte Membrane) fuel cell.

Isometric — a mathematical term that comes from the Greek for “equal measure,” reflecting a congruent relationship between two geometric figures or structures such that to each part of one structure there is a corresponding part in the other structure. If an object changes isometrically as a result of a uniform scaling (enlarging or shrinking), it retains geometric similarity in size and shape of the other.

Lipids — a diverse group of organic molecules that contain long hydrocarbon chains or rings and are hydrophobic; examples are fats, oils, waxes, and steroids.

Macroscale — scale at which objects are large enough to be observed by the naked eye.

Magnetic resonance imaging (MRI) — a noninvasive diagnostic technique that uses nuclear magnetic resonance (magnetic response of an atom’s nucleus with radio waves) to produce cross-sectional computer images of organs and other internal body structures. It is invaluable in detecting and delineating tumors and in providing images of the brain, the heart, and other soft-tissue organs because it provides excellent contrast between normal and diseased tissues.

Maillard (browning) reaction — a chemical reaction between an amino acid (from protein) and a sugar, usually requiring heat; although used since ancient times, the reaction is named after the chemist Louis-Camille Maillard who first investigated it in 1910. The Maillard reaction is responsible for many colors and flavors in foods, such as roasted or seared meat, roasted coffee, chocolate, maple syrup, roasted peanuts, aromatic varieties of cooked rice, and the biscuit or crackerlike flavor present in baked goods like toasted bread, popcorn, and tortilla products.

Microscale — (Greek: “micron” = small, “skopein” = to look at); the scale at which objects are at the “micrometer-size,” too small to be seen with the naked eye unless aided by a light microscope. The microscale is intermediate between macroscale and nanometer scale; the lower end of the microscale is typically around 0.2 micrometers (0.2 3 10-6 m 5 200 nm), which is the practical limit of the light microscope.

Nanocos (card game) — an interactive card game developed for learning nanotechnology concepts; players will become familiar with the size of objects spanning many size scales, including the nanoscale; players also learn about important tools and instruments used at the nanoscale, as well as many unique properties of nanoscale objects.

Nanometer — a metric unit of length equal to one billionth of a meter:
1 nm = 1 3 10-9 m; 1.0 nm = 10 A (angstroms).

Nanoparticle — a very minute particle whose size is measured in the approximate range of 1–100 nm.

Nanoscale — relating to or occurring on a scale of nanoparticles (1–100 nm).

Nanotechnology — technology development whose unifying theme is the control of matter on the atomic, molecular, or macromolecular scale of approximately 1–100 nanometers to create and use structures, devices, and systems that have novel properties.

Nanotube — a cylindrical carbon molecule with properties that make them potentially useful in extremely small scale electronic and mechanical applications; they exhibit unusual strength, unique electrical properties, and are efficient conductors of heat.

Nucleating agent — a substance or particle whose surfaces act as a nucleus or starting point around which molecules collect to begin a phase transition in a small region; the phase transition can be the formation of a bubble from a pressurized liquid such as a carbonated beverage or the formation of crystal from liquid such as freezing of water.

Orbitals (bonding electron) — describes what an electron with a given energy is doing inside an atom or molecule.

Polar attraction — refers to the dipole-dipole intermolecular forces between the slightly positively-charged end of one molecule to the slightly negatively-charged end of another molecule.

Prototype — the first or original model of a product, which is built to experiment with the function and feel of the new design and to see if changes to the design are necessary prior to constructing the final product. In many fields, “rapid-prototyping” techniques are used to implement part, but not all, of the complete design. This allows designers and manufacturers to rapidly and inexpensively experiment with parts of the design that are most likely to have problems, solve those problems, and then build the full design.

Quantum mechanics — (also called wave mechanics) a modern theory of atomic structure based on the wave property of matter. Quantum theory is able to explain facts that previous physical theories were unable to account for, in particular, the fact that energy is absorbed and released in small, discrete quantities called quanta, and that all matter displays both wavelike and particlelike properties, especially when viewed at atomic and subatomic scales. Quantum mechanics suggests that the behavior of matter and energy is inherently probabilistic and that the effect of the observer on the physical system being observed must be understood as a part of that system.

Reaction (self-sustaining) — a chain reaction that, once started, continues without further outside influence. A chain reaction can be of various types, but nuclear chain reactions are the best known. A line of dominoes falling after the first one has been pushed is an example of a mechanical chain reaction. A pile of wood burning after it has been kindled is an example of a chemical chain reaction; each piece of wood, as it burns, must release enough heat to raise the temperature of nearby pieces to the kindling point to continue the combustion process.

Scanning electron microscope (SEM) — a type of microscope that uses electrons instead of light as a way to illuminate and create a three-dimensional image of a specimen. The scanning electron microscope moves a beam of narrowly focused electrons back and forth across an object and detects both the electrons that are scattered by the object and the electrons knocked loose from the object to produce a three-dimensional pattern of the specimen surface. It has much higher magnification and resolving power than a light microscope, with magnifications up to about two million times, compared to about two thousand that can be achieved with visible light microscopes.

Solar cell — (also photovoltaic cell) a device that transfers light energy of photons into electrical energy of moving charges, typically consisting of layers or sheets of specially prepared silicon. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified. Solar cells are used as power supplies in calculators, satellites, and other devices, and as a primary source of electricity in remote locations.

Scanning transmission electron microscope (STEM) — a type of electron microscope, but, unlike scanning electron microscopes used to look at surfaces of materials that move a focused beam over the sample, the electron beam in STEM passes through the specimen in order to study the interiors of materials. Thus, in order to use the transmission electron microscope, specimens must undergo special preparation; because the electrons do not have very high penetrating power, all samples must be sliced into 50 to 100 nm thin sections.

Structure (crystalline) — like a crystal, containing or consisting of the nature of crystal structure; it implies a solid having a regular arrangement of atoms, molecules, or ions that are packed in an ordered, repeating pattern extending uniformly in all three spatial dimensions. In contrast, an amorphous solid is a noncrystalline material with a lack of long-range structure.

Superabsorbent polymer (SAP) — polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass. Water absorbing polymers, classified as hydrogels, absorb aqueous solutions through hydrogen bonding with the water molecule; in deionized and distilled water, SAP may absorb 500 times its weight, but when put into a 0.9% saline solution, the absorbency drops to approximately 50 times its weight. Polyacrylate (polymer used in diapers) is the most common type of SAP made in the world today; superabsorbent polyacrylamide is the polymer used in this module.

Superorganism — a group of organisms, such as an insect colony, that functions as a single social unit, where division of labor is highly specialized and where individuals are not able to survive by themselves for extended periods of time. Ants and bees are the most well known examples of such a superorganism.

Surface area-to-volume ratio (SA/V) — a numerical quotient of the total area of the surface of a 3-D solid divided by the total amount of space the 3-D object occupies. It changes with size and shape and becomes increasingly important at the nanoscale. A high surface area-to-volume ratio, e.g., very small diameter, or very porous or very spread out, also means that a solid object has increased contact with the environment through the surface of the object relative to its volume. This can speed up reaction rates in a chemical reaction or increase the nutrient uptake in a biological organism.

Surface tension — a property of liquids arising from unbalanced molecular cohesive forces at or near the surface, as a result of which the surface tends to contract and has properties resembling those of a stretched elastic membrane. Due to surface tension, the surface of a liquid can support light objects such as water beetles on the surface of a pond. Surface tension is responsible for the spherical shape of drops of liquid since spheres minimize the surface area of the drop and thus minimize surface tension.

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