Absorption (EM radiation)
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The process by which the energy of a photon is taken up by matter, typically the electrons of an atom. The electromagnetic energy is transformed to another form of energy, e.g. to heat.
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Absorption (physical)
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A physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase - gas, liquid or solid material. This is a different from Adsorption, since the molecules are taken up by the volume, not by surface.
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Bingham Plastic
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A viscoplastic material that behaves as a rigid body at low stresses but flows as a viscous fluid at high stress. A common example is toothpaste, which will not be extruded until a certain pressure is applied to the tube. It then is pushed out as a solid plug.
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Colloid
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A type of chemical mixture where one substance is dispersed evenly throughout another. The particles of the dispersed substance are only suspended in the mixture, unlike a solution, where they are completely dissolved within. This occurs because the particles in a colloid are larger than in a solution - small enough to be dispersed evenly and maintain a homogenous appearance, but large enough to scatter light and not dissolve.
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Combustion
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(or burning) A complex sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. Direct combustion by atmospheric oxygen is a reaction mediated by radical intermediates typically produced as a result of thermal runaway, where the heat generated by combustion is necessary to maintain the high temperature necessary for radical production.
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Conduction (electrical)
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The movement of electrically charged particles through a transmission medium (electrical conductor). The movement of charge constitutes an electric current. The charge transport may result as a response to an electric field, or as a result of a concentration gradient in carrier density, that is, by diffusion .
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Conduction (thermal)
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The spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature. Conduction acts to equalize temperature differences. It is also described as heat energy transferred from one material to another by direct contact.
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Cooling
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The act of reducing temperature.
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Deflagration
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A technical term describing subsonic combustion that usually propagates through thermal conductivity (hot burning material heats the next layer of cold material and ignites it). Most 'fire' found in daily life, from flames to explosions, is technically deflagration. Deflagration is different from detonation (which is supersonic and propagates through shock compression).
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Desorption
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A phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption (i.e adsorption and absorption). This occurs in a system being in the state of sorption equilibrium between bulk phase (fluid, i.e. gas or liquid solution) and an adsorbing surface (solid or boundary separating two fluids). When the concentration (or pressure) of substance in the bulk phase is lowered, some of the sorbed substance changes to the bulk state.
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Detonation
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Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases.
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Dielectric Heating
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(also known as electronic heating, RF heating, high-frequency heating) The phenomenon in which radiowave or microwave electromagnetic radiation heats a dielectric material, especially as caused by dipole rotation.
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Eddy Currents
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An electrical phenomenon caused when a conductor is exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. This can cause eddys of circulating current within the conductor which create electromagnets with magnetic fields that opposes the change of the magnetic field.
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Through inductive heating
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Electron Impact Desorption
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Desorption arising from electron-impact induced adsorbate surface bond breaking. Molecules on surfaces may also be chemically converted to other species by electron impact
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Electrorheological Effect
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Electrorheological (ER) fluids are suspensions of extremely fine non-conducting particles (up to 50 micrometres diameter) in an electrically insulating fluid. The apparent viscosity of ER fluids changes reversibly by an order of up to 100,000 in response to an electric field. A typical ER fluid can go from the consistency of a liquid to that of a gel, and back, with response times of the order of ms. Sometimes called the Winslow Effect.
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Evaporation
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The change of the physical state of aggregation (or simply state) of matter from liquid phase to gaseous phase.
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Exothermic Reaction
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An exothermic reaction is a chemical reaction accompanied by the release of heat. In other words, the energy needed for the reaction to occur is less than the total energy released. As a result of this, the extra energy is released, usually in the form of heat.
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Explosion
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A sudden increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases.
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Fluidisation
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A process similar to liquefaction whereby a granular material is converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas) is passed up through the granular material. When fluidized, a bed of solid particles will behave as a fluid, like a liquid or gas.
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Heating
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The act of increasing temperature.
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Hydrophile
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A physical property of a molecule that can transiently bond with water (H2O) through hydrogen bonding. This is thermodynamically favorable, and makes these molecules soluble not only in water, but also in other polar solvents.
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Infrared Radiation
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Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light (400-700 nm), but shorter than that of terahertz radiation (3-300 µm) and microwaves (~30,000 µm). Infrared radiation spans roughly three orders of magnitude (750 nm and 1000 µm).
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Joule Heating
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The process by which the passage of an electric current through a conductor releases heat. Heat generated is a function of current, resistance and time. Also known as the Joule-Lenz effect, Ohmic heating or resitive heating.
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Latent Heat
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Energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process. An example is a state of matter change, meaning a phase transition, such as ice melting or water boiling.
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Melting
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A process that results in the phase change of a substance from a solid to a liquid. The internal energy of a solid substance is increased (typically by the absorbtion of heat) to a specific temperature (called the melting point) at which it changes to the liquid phase.
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Nuclear Fission
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The splitting of the nucleus of an atom into parts (lighter nuclei) often producing free neutrons and other smaller nuclei, which may eventually produce photons (in the form of gamma rays). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place).
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Nuclear Fusion
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The generation of power by the fusing together of atomic nuclei to form a heavier nucleus.
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Phase Change
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The transformation of a thermodynamic system from one phase to another. Most commonly used to describe transitions between solid, liquid and gaseous states of matter, in rare cases including plasma.
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Plasma
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A partially ionized gas, in which a certain proportion of electrons are free rather than being bound to an atom or molecule. The ability of the positive and negative charges to move somewhat independently makes the plasma electrically conductive so that it responds strongly to electromagnetic fields. Plasma therefore has properties quite unlike those of solids, liquids or gases and is considered to be a distinct state of matter.
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Radiation
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A process in which energetic particles or waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing.
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Solvation
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(commonly called dissolution) The process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules. The bigger the ion, the more solvent molecules are able to surround it and the more it becomes solvated.
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Sorption
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The action of both absorption and adsorption taking place simultaneously, i.e. the effect of gases or liquids being incorporated into a material of a different state and adhering to the surface of another molecule. Absorption is the incorporation of a substance in one state into another of a different state (e.g., liquids absorbed by solid or gas absorbed by liquid). Adsorption is the physical adherence or bonding of ions and molecules onto the surface of another molecule.
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Sublimation
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The change of the physical state of aggregation (or simply state) of matter directly from solid phase to gaseous phase without passing through an intermediate liquid phase.
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Supersaturation
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A solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances. It can also refer to a vapour of a compound that has a higher (partial) pressure than the vapour pressure of that compound.
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Temperature Gradient
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The variation in temperature over distance.
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Thermal Radiation
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Electromagnetic radiation emitted from the surface of an object due to the object's temperature.
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Thermolysis
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(or Thermal decomposition) A chemical decomposition caused by heat. The reaction is usually endothermic as heat is required to break chemical bonds in the compound undergoing decomposition. If decomposition is sufficiently exothermic, a positive feedback loop is created producing thermal runaway and possibly an explosion.
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Thixotropy
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The property of some non-Newtonian pseudoplastic fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite amount of time to attain equilibrium viscosity when introduced to a step change in shear rate. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated.
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Some thixotrophic materials have a divided solid as one of their constituents, e.g. some clays.
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Viscoelasticity
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The property of exhibiting both viscous and elastic characteristics when undergoing deformation.
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