Vitrification 305927 222475299 2008-06-29T15:17:36Z DOI bot 6652755 Citation maintenance. Formatted: journal. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. [[Image:Vitrification1.jpg|thumb|right|300px|A vitrification experiment for the study of nuclear waste disposal at [[Pacific Northwest National Labs]]]] '''Vitrification''' is a process of converting a material into a [[glass]]-like [[amorphous solid]] that is free from any [[crystal]]line structure, either by the quick removal or addition of [[heat]], or by mixing with an additive. Solidification of a [[vitreous]] solid occurs at the [[glass transition temperature]] (which is lower than [[melting point|melting temperature]], ''T''<sub>m</sub>, due to [[supercooling]]). When the starting material is solid, vitrification usually involves heating the substances to very high [[temperature]]s. Many [[ceramic]]s are produced in such a manner. Vitrification may also occur naturally when [[lightning]] strikes [[sand]], where the extreme and immediate heat can create hollow, branching rootlike structures of glass, called [[fulgurite]]. When applied to whiteware ceramics, vitreous means the material has an extremely low [[permeability (fluid)|permeability]] to liquids, often but not always water, when determined by a specified test regime. The microstructure of whiteware ceramics frequently contain both [[amorphous]] and crystalline phases. ==Examples== When [[sucrose]] is cooled slowly, the result is crystal [[sugar]] (or [[rock candy]]), but, when cooled rapidly, the result can be in the form of syrupy [[cotton candy]] (candyfloss). Vitrification can also occur when starting with a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of [[ice]] crystals. Additives used in [[cryobiology]] or produced naturally by organisms living in [[polar region]]s are called [[cryoprotectant]]s. [[Wood Frog|Arctic frog]]s and some other [[ectotherm]]s naturally produce [[glycerol]] or [[glucose]] in their [[liver]]s to reduce ice formation. When glucose is used as a cryoprotectant by Arctic frogs, massive amounts of glucose are released at low temperature<ref>{{cite journal | author=Jack R. Layne, Jr., Richard E. Lee, Jr. | title=Adaptations of frogs to survive freezing | journal=Climate Research | volume=5 | year=1995 | pages=53–59 |url=http://www.int-res.com/articles/cr/5/c005p053.pdf | doi=10.3354/cr005053}}</ref>, and a special form of [[insulin]] allows for this extra glucose to enter the cells. When the frog rewarms during [[spring (season)|spring]], the extra glucose must be rapidly removed from the cells and recycled via renal excretion and storage in the bladder. Arctic [[insect]]s also use sugars as cryoprotectants. Arctic fish use [[antifreeze protein]]s, sometimes appended with sugars, as cryoprotectants. ==Applications== Ordinary soda-lime [[glass]], used in windows and drinking containers, is created by the addition of [[sodium carbonate]] and lime ([[calcium oxide]]) to [[silicon dioxide]]. Without these additives, silicon dioxide will (with slow cooling) form [[sand]] or [[quartz]] crystal, not glass. Vitrification is a proven technique in the disposal and long-term storage of [[nuclear waste]] or other hazardous wastes<ref>M. I. Ojovan, W.E. Lee. ''An Introduction to Nuclear Waste Immobilisation'', Elsevier, Amsterdam, 315pp. (2005) </ref>. Waste is mixed with glass-forming chemicals to form molten glass that then solidifies, immobilizing the waste. The final waste form resembles [[obsidian]] and is a non-[[leaching]], durable material that effectively traps the waste inside. The waste can be stored for relatively long periods in this form without concern for [[air pollution|air]] or [[groundwater]] [[radioactive contamination|contamination]]. Bulk vitrification uses [[electrode]]s to melt soil and wastes where they lay buried. The hardened waste may then be disinterred with less danger of widespread contamination. According to the [[Pacific Northwest National Labs]], "Vitrification locks dangerous materials into a stable glass form that will last for thousands of years."<ref name="Waste">{{cite web | title = Waste Form Release Calculations for the 2005 Integrated Disposal Facility Performance Assessment | work = PNNL-15198 | publisher = Pacific Northwest National Laboratory | date = July, 2005 | format = [[PDF]] | url=http://www.pnl.gov/main/publications/external/technical_reports/PNNL-15198.pdf | accessdate = 2006-11-08 }}</ref> [[Ethylene glycol]] is used as automotive [[antifreeze]] and [[propylene glycol]] has been used to reduce ice crystals in [[ice cream]], making it smoother. For years, [[glycerol]] has been used in [[cryobiology]] as a cryoprotectant for blood cells and [[artificial insemination|bull sperm]], allowing storage at [[liquid nitrogen]] temperatures. However, glycerol cannot be used to protect whole [[organ (anatomy)|organs]] from damage. Instead, many biotechnology companies are [[as of 2005|currently]] researching the development of other cryoprotectants more suitable for such uses. A successful discovery may eventually make possible the bulk [[cryogenics|cryogenic]] storage (or "banking") of [[organ transplant|transplantable]] human and [[xenobiotic]] organs. A substantial step in that direction has already occurred. At the July 2005 annual conference of the Society for [[Cryobiology]]<ref name="Kidney">{{cite web | title = Plenary Session: Fundamentals of Biopreservation | work = CRYO 2005 Scientific Program | publisher = Society for Cryobiology | date = Sunday, July 24, 2005 | url=http://www.me.umn.edu/events/cryo2005/program.html | accessdate = 2006-11-08 }}</ref>, [[Twenty-First Century Medicine]] announced the vitrification of a [[rabbit]] [[kidney]] to -135°C with their proprietary vitrification cocktail. Upon rewarming, the kidney was successfully transplanted into a rabbit, with complete functionality and viability. In the context of [[cryonics]], especially in preservation of the [[human brain]], vitrification of tissue is thought to be necessary to prevent destruction of the tissue or information encoded in the brain. At present, vitrification techniques have only been applied to brains ([[neurovitrification]]) by [[Alcor Life Extension Foundation|Alcor]] and to the upper body by the [[Cryonics Institute]], but research is in progress by both organizations to apply vitrification to the whole body. ==References== <references/> *Steven Ashle, ''Divide and Vitrify,'' June 2002, Scientific American *Stefan Lovgren, ''Corpses Frozen for Future Rebirth by Arizona Company,'' March 2005, National Geographic *Vitrification: Putting the Heat on Waste ==See also== *[[Cryogenics]] *[[Cryobiology]] *[[Cryonics]] *[[Cryopreservation]] *[[List of emerging technologies]] *[[Radioactive_waste#Vitrification|Radioactive waste vitrification]] *[[Supercooling]] ==External links== *[http://www.benbest.com/cryonics/vitrify.html Vitrification in Cryonics] *[http://www.21cm.com/abstract.jsp?AID=62&SPub=&STitle=&SAuthor=&SDateStart=mm%2Fyyyy&SDateStop=mm%2Fyyyy&STopic=&SKeywords=&Page=1 CRYOBIOLOGY 48(1):22-35 (2004)] *[http://regionalaffairs.pnl.gov/seminars/speakers/sundaram.stm Vitrification: Putting the Heat on Waste] *[http://eprints.iisc.ernet.in/archive/00000257/01/kjrao.pdf Fragility thy name is glass] *[http://www.public.asu.edu/~caangell/Abstracts/395.pdf Liquid fragility and the glass transition in water and aqueous solutions] [[Category:Chemical processes]] [[Category:Cryobiology]] [[Category:Glass engineering and science]] [[ar:تزجيج]] [[cs:Vitrifikace]] [[de:Vitrifizierung]] [[es:Vitrificación]] [[fr:Vitrification (recyclage)]] [[pl:Witryfikacja]] [[ru:Витрификация]] [[sv:Vitrifikation]]