Adiabatic Heating
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Adiabatic heating occurs when the pressure of a gas is increased from work done on it by its surroundings, e.g. a piston. Diesel engines rely on adiabatic heating during their compression stroke to elevate the temperature sufficiently to ignite the fuel.
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Avalanche Breakdown
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A phenomenon that can occur in both insulating and semiconducting materials (solids, liquids, or gases), allowing very large currents to flow within materials which are otherwise good insulators. Occurs when the electric field in the material is great enough to accelerate free electrons to the point that, when they strike atoms in the material, they can knock other electrons free: the number of free electrons is thus increased rapidly as newly generated particles become part of the process.
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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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Boiling
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A type of phase transition. The rapid vaporisation of a liquid, which typically occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding environmental pressure.
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Capillary Evaporation
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The transport of a liquid from within a capillary system (e.g. a block of porous material) and the subsequent evaporation from its surface.
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By lowering temperature through latent heat of evaporation
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Coagulation
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A complex process by which blood forms clots. It is an important part of hemostasis (the cessation of blood loss from a damaged vessel) whereby a damaged blood vessel wall is covered by a platelet and fibrin containing clot to stop bleeding and begin repair of the damaged vessel.
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In the sense of a liquid (blood) changing to a solid form (clot).
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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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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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Through heating resulting from the flow of current.
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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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Crystallisation
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The (natural or artificial) process of formation of solid crystals precipitating from a identical solution or melt, or more rarely deposited directly from a gas. Crystallisation is also a chemical solid-liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.
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Depressurisation
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Reduction in pressure. Rapid depressurisation can be used to create pressure differences.
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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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Electric Arc
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An electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air
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Endothermic Reaction
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A process or reaction that absorbs energy typically (but not always) in the form of heat. The concept is frequently applied in physical sciences to e.g. chemical reactions, where thermal energy (heat) is converted to chemical bond energy.
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Entropic Explosion
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An explosion in which the reactants undergo a large change in volume without releasing a large amount of heat.
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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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By lowering temperature through latent heat of evaporation
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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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Fermentation
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In an industrial context, fermentation refers to the breakdown of organic substances and re-assembly into other substances. Somewhat paradoxically, fermenter culture in industrial capacity often refers to highly oxygenated and aerobic growth conditions, whereas fermentation in the biochemical context is a strictly anaerobic process.
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Not a phase change in the strict sense of the term, but nonetheless a way of transforming a liquid into a gas.
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Freezing
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A phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. Colloquially it is applied to water, but technically it applies to any liquid. All known liquids, except liquid helium, freeze when the temperature is lowered enough.
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Gel
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A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute crosslinked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional crosslinked network within the liquid. It is the crosslinks within the fluid that give a gel its structure (hardness) and contribute to stickiness (tack).
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In the sense that a liquid component of a gel behaves somewhat like a solid.
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Heating
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The act of increasing temperature.
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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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From energy of incident infrared radiation.
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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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Leidenfrost Effect
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A phenomenon in which a liquid, in near contact with a mass significantly hotter than its boiling point, produces an insulating vapour layer which keeps that liquid from boiling rapidly. Due to this repulsive force, the droplet hovers over the surface rather than making physical contact with it. Commonly seen in the case of droplets of water skittering across a very hot metal surface.
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Magnetoelastic Effects
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A group of effects including Magnetostriction (or Joule Magnetostriction), Delta-E Effect, Wiedemann Effect, Magnetovolume Effect, and their Inverses: Villari Effect, Delta-E Effect, Matteucci Effect and the Nagaoka-Honda Effect.
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Through heating resulting from collapse of cavitation bubbles resulting from the manetostriction effect on a magnetic liquid.
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Magnetostriction
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A property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetisation. The variation of material's magnetisation due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation value. This effect can cause losses due to frictional heating in susceptible ferromagnetic cores.
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Through heating resulting from collapse of cavitation bubbles resulting from the manetostriction effect on a magnetic liquid.
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Nucleation
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The extremely localised budding of a distinct thermodynamic phase. Some examples of phases that may form via nucleation in liquids are gaseous bubbles, crystals or glassy regions. Creation of liquid droplets in saturated vapor is also characterized by nucleation. Most nucleation processes are physical, rather than chemical, but a few exceptions do exist (e.g. electrochemical nucleation).
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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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Pressure Drop
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Pressure is an effect which occurs when a force is applied on a surface. Pressure is transmitted to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. Rapid pressure drop is a useful technique for applying force or breaking objects apart.
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Pressurisation
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The application of pressure in a given situation or environment; and more specifically refers to the process by which atmospheric pressure is maintained in an isolated or semi-isolated atmospheric environment (for instance, in an aircraft, or whilst scuba diving).
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Regelation
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The phenomenon of melting under pressure and freezing again when the pressure is reduced. Occurs only for substances, such as ice, that have the property of expanding upon freezing, for the melting points of those substances decrease with increasing external pressure.
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Sonochemistry
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The effect of sonic waves and wave properties on chemical systems. Sonochemistry arises from acoustic cavitation: the formation, growth, and implosive collapse of bubbles in a liquid. This is demonstrated in phenomena such as ultrasound, sonication, sonoluminescence, and sonic cavitation.
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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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Suction
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The flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area.
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Low pressure may cause a liquied to boil/evaporate
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Supercritical Fluid
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Any substance at a temperature and pressure above its critical point. It can diffuse through solids like a gas, and dissolve materials like a liquid. Additionally, close to the critical point, small changes in pressure or temperature result in large changes in density, allowing many properties to be 'tuned'.
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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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A hot liquid (e.g. molten metal) cools as a result of the loss of energy required to generate the thermal radiation
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Ultrasonic Vibration
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Vibration at ultrasonic frequencies.
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Ultrasound
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Cyclic sound pressure with a frequency greater than the upper limit of human hearing. Although this limit varies from person to person, 20 kHz serves as a useful lower limit in describing ultrasound.
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The ultrasonic humidifier, one type of nebulizer (a device that creates a very fine spray), is a popular type of humidifier. It works by vibrating a metal plate at ultrasonic frequencies to nebulize (sometimes incorrectly called 'atomize') the water.
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Vacuum
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A volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in practice. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they simply call 'vacuum' or 'free space', and use the term partial vacuum to refer to real vacuum.
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Viscous Heating
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The work done by a fluid on adjacent layers due to the action of shear forces is transformed into heat.
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