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Encyclopedia > Perfluorocarbon
Fluorotelomer alcohol FTOH 8:2

Perfluorocarbons (PFCs) are compounds derived from hydrocarbons by replacement of hydrogen atoms by fluorine atoms. PFCs are made up of atoms of carbon, fluorine, and/or sulfur. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Oil refineries are key to obtaining hydrocarbons; crude oil is processed through several stages to form desirable hydrocarbons, used in fuel and other commercial products. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Properties In chemistry and physics, an atom (Greek ἄτομος or átomos meaning indivisible) is the smallest particle still characterizing a chemical element. ... General Name, Symbol, Number fluorine, F, 9 Chemical series halogens Group, Period, Block 17, 2, p Appearance Yellowish brown gas Atomic mass 18. ... General Name, symbol, number carbon, C, 6 Chemical series nonmetals Group, period, block 14, 2, p Appearance black (graphite) colorless (diamond) Standard atomic weight 12. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Standard atomic weight 32. ...

Contents

Medicine

Perfluorocarbons are commonly used in eye surgery as temporary replacements of the vitreous humor in retinal detachment surgery. The length of the perfluorated carbon chain determines the physical properties of a particular perfluorocarbon. Small chain perfluorocarbons, such as perfluoro-propane, are gases that rise inside the eye and seal retinal holes. Larger chain perfluorocarbons, such as perfluoro-octane, are liquids heavier than water and are used in surgery to immobilize an infolded retina. Eye surgery in the middle ages. ... Vitreous humour is the clear gel that fills the eyeball, lying between the lens and the retina in the eye. ... Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. ...


Perfluorocarbons are also used in contrast-enhanced ultrasound to improve ultrasound signal backscatter. The perfluorocarbons used in the microbubbles of some ultrasound contrast media are liquids at room temperature, but gases at body temperature. The gas-filled microbubbles oscillate and vibrate when a sonic energy field is applied and characteristically reflect ultrasound waves. This distinguishes the microbubbles from surrounding tissues. Contrast-enhanced ultrasound (CEU) is the application of ultrasound contrast agents to traditional medical sonography. ... Ultrasound is a form of cyclic sound pressure with a frequency greater than the upper limit of human hearing, this limit being approximately 20 kilohertz (20,000 hertz). ...


Their stability, inertness, low diffusion rate and solubility increase the duration of contrast enhancement as compared to microbubbles containing air. The uses of PFCs in artificial blood and liquid breathing are currently being investigated. The theory behind liquid breathing is that, since perfluorocarbons carry oxygen so well, a person should be able to breathe normally with lungs filled with perfluorocarbon fluids. However, in practice liquid breathing has so far proved to be problematic; trials on animals have shown evidence of lung damage and carbon dioxide build-up from respiration. In addition, as perfluorocarbon liquids (and liquids in general) are much denser and more viscous than air, rates of breathing, and therefore of gas exchange, are limited. In English, to be inert is to be in a state of doing little or nothing. ... This article does not cite any references or sources. ... Solubility refers to the ability for a given substance, the solute, to dissolve in a solvent. ... Blood substitutes are used to fill fluid volume and/or carry oxygen and other gases in the cardiovascular system. ... Liquid breathing is a form of respiration in which someone breathes an oxygen rich liquid (usually from the perfluorocarbon family), rather than breathing air. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Standard atomic weight 15. ... Liquid breathing is a form of respiration in which someone breathes an oxygen rich liquid (usually from the perfluorocarbon family), rather than breathing air. ...


Industry and the environment

PFCs are being used in refrigerating units and "clean" fire extinguishers. However, PFCs are extremely potent greenhouse gases, and they are a long-term problem with a lifetime up to 50,000 years (PMID 14572085). In a 2003 study, the most abundant atmospheric PFC was tetrafluoromethane (PMID 14572085). The greenhouse warming potential (GWP) of tetrafluoromethane is 6,500 times that of carbon dioxide, and the GWP of hexafluoroethane is 9,200 times that of carbon dioxide.[1] Several governments concerned about the properties of PFCs have already tried to implement international agreements to limit their usage before it becomes a global warming issue. PFCs are one of the classes of compounds regulated in the Kyoto Protocol. Larger PFC compounds include PFOS and PFOA, which are persistent in the environment and are detected in blood samples all over the world. Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. ... Fire extinguisher A fire extinguisher is a device used to put out a fire, often in an emergency situation. ... Carbon tetrafluoride, CF4, is a carbon fluoride. ... In order to meet Wikipedias quality standards, this article requires cleanup. ... Flash point Non-flammable Supplementary data page Structure and properties n, εr, etc. ... Kyoto Protocol Opened for signature December 11, 1997 in Kyoto, Japan Entered into force February 16, 2005. ... Perfluorooctanoic acid (PFOA) is an artificial acid that has many industrial uses. ... Perfluorooctanoic acid (PFOA) is an artificial acid that has many industrial uses. ...


See also

Fluorinertâ„¢ is the brand name for the line of electronics coolant liquids sold commercially by 3M. It is an electrically insulating, inert perfluorocarbon fluid which is used in various cooling applications but is mainly for cooling electronics. ... A coolant, or heat transfer fluid, is a fluid which flows through a device in order to prevent its overheating, transferring the heat produced by the device to other devices that utilize or dissipate it. ... 3M Company (NYSE: MMM), formerly Minnesota Mining and Manufacturing Company until 2002, is an American corporation with a worldwide presence. ... A fluoropolymer is a polymer that contains atoms of fluorine. ... Liquid breathing is a form of respiration in which someone breathes an oxygen rich liquid (usually from the perfluorocarbon family), rather than breathing air. ...

External link

  • Perfluorocarbons as a transport for Oxygen to the lungs, e.g. partial liquid ventilation.
  • Envionmental Working Group defines PFC health concerns.

  Results from FactBites:
 
editorial octobre 99 virtanes (2403 words)
Perfluorocarbons are a promising new class of molecules without direct toxicity, and possessing interesting properties on the respiratory gases as well as on the other inert gases.
Perfluorocarbons are not metabolized but are cleared from the vascular space by the reticuloendothelial system and collected in the liver and spleen, eventually leaving the body as a vapor in the respiratory gases (15).
The concentration of perfluorocarbons reached in plasma is measured by the fluorocrit that is defined as the relative height of the column of perfluorocarbons in spun whole blood.
Medical Applications : Perfluorodecalin, Perfluorohexane, Octafluoropropane, Perfluoroperhydrophenanthrene, ... (1011 words)
For many years a huge amount of interest has been shown in perfluorocarbons for medical applications due to their remarkably low toxicity, lack of biological activity, short retention time in the body and their ability to dissolve gases especially oxygen and carbon dioxide.
Perfluorocarbons are immisible with blood so they are used in an emulsion form.
Perfluorocarbons emulsions have a relatively small particle size and so have the added advantage that they are able to oxygenate ischaemic tissue and tumours (increasing sensitivity to radiation therapy).
  More results at FactBites »

 
 

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