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Zinc, also referred to in nonscientific contexts as spelter, [encyclo.co.uk] is a bluish-white, lustrous, diamagnetic metal, [CRC 2006] though most common commercial grades of the metal have a dull finish. [Heiserman 1992]:123 It is somewhat less dense than iron and has a hexagonal crystal structure. [Lehto 1968]:826
The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C.[CRC 2006] [Heiserman, 1992:123] Above 210 °C, the metal becomes brittle again and can be pulverized by beating. [Scoffern 1861] Zinc is a fair conductor of electricity. [CRC 2006] For a metal, zinc has relatively low melting (420 °C) and boiling points (900 °C). [galvanizeit.org] Its melting point is the lowest of all the transition metals aside from mercury and cadmium. [galvanizeit.org]
Many alloys contain zinc, including brass, an alloy of zinc and copper. Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium and sodium. [Ingalls 1902] While neither zinc nor zirconium are ferromagnetic, their alloy ZrZn2 exhibits ferromagnetism below 35 K. [CRC 2006]
Zinc makes up about 75 ppm (0.007%) of the Earth's crust, making it the 24th most abundant element there. [Emsley 2001]:503 Soil contains 5–770 ppm of zinc with an average of 64 ppm.[Emsley 2001]:503 Seawater has only 30 ppb zinc and the atmosphere contains 0.1–4 µg/m3. [Emsley 2001]:503
The element is normally found in association with other base metals such as copper and lead in ores.[Lehto 1968]:822 Zinc is a chalcophile ("sulfur loving"), meaning the element has a low affinity for oxygen and prefers to bond with sulfur in highly insoluble sulfides. Chalcophiles formed as the crust solidified under the reducing conditions of the early Earth's atmosphere. [Greenwood 1997]:1202 Sphalerite, which is a form of zinc sulfide, is the most heavily mined zinc-containing ore because its concentrate contains 60–62% zinc. [Lehto 1968]:822
Other minerals, from which zinc is extracted, include smithsonite (zinc carbonate), hemimorphite (zinc silicate), wurtzite (another zinc sulfide), and sometimes hydrozincite (basic zinc carbonate).[Emsley 2001]:502 With the exception of wurtzite, all these other minerals were formed as a result of weathering processes on the primordial zinc sulfides. [Greenwood 1997]:1202
World zinc resources total about 1.8 gigatonnes.[usgs.gov 2009] Nearly 200 megatonnes were economically viable in 2008; adding marginally economic and subeconomic reserves to that number, a total reserve base of 500 megatonnes has been identified. [usgs.gov 2009] Large deposits are in Australia, Canada and the United States.[Greenwood 1997]:1202 At the current rate of consumption, these reserves are estimated to be depleted sometime between 2027 and 2055.[Cohen 2007] [idtechex.com] About 346 megatonnes have been extracted throughout history to 2002, and one estimate found that about 109 megatonnes of that remains in use. [Gordon 2006]
Zinc is an essential trace element, necessary for plants,[Broadley 2007] animals, [Prasad 2008] and microorganisms.[Sugarman 1983] Zinc is found in nearly 100 specific enzymes [NRC 2000]:443 (other sources say 300), serves as structural ions in transcription factors and is stored and transferred in metallothioneins.[Cotton 1999]:625–629 It is "typically the second most abundant transition metal in organisms" after iron and it is the only metal which appears in all enzyme classes.[Broadley 2007]
There are 2–4 grams of zinc[Rink 2000] distributed throughout the human body. Most zinc is in the brain, muscle, bones, kidney, and liver, with the highest concentrations in the prostate and parts of the eye.[Wapnir 1990]:131 Semen is particularly rich in zinc, which is a key factor in prostate gland function and reproductive organ growth.[Berdanier 2007]:210
In humans, zinc plays "ubiquitous biological roles".[Hambridge 2007] It interacts with "a wide range of organic ligands",[Hambridge 2007] and has roles in the metabolism of RNA and DNA, signal transduction, and gene expression. It also regulates apoptosis. A 2006 study estimated that about 10% of human proteins (2800) potentially bind zinc, in addition to hundreds which transport and traffic zinc; a similar in silico study in the plant Arabidopsis thaliana found 2367 zinc-related proteins.[Broadley 2007]
In the brain, zinc is stored in specific synaptic vesicles by glutamatergic neurons [Bitanihirwe 2009] and can "modulate brain excitability".[Hambridge 2007] It plays a key role in synaptic plasticity and so in learning.[Nakashima 2009] However it has been called "the brain's dark horse"[Bitanihirwe 2009] since it also can be a neurotoxin, suggesting zinc homeostasis plays a critical role in normal functioning of the brain and central nervous system.[Bitanihirwe 2009]
- [Bitanihirwe 2009] ^ 1 2 3 Bitanihirwe BK, Cunningham MG (2009). «Zinc: The brain's dark horse». Synapse 63. PMID 19623531.
- [Nakashima 2009] ^ Nakashima AS, Dyck RH (2009). «Zinc and cortical plasticity». Brain Res Rev 59. DOI:10.1016/j.brainresrev.2008.10.003. PMID 19026685.
- [Hambridge 2007] ^ 1 2 3 Hambidge, K. M. and Krebs, N. F. (2007). «Zinc deficiency: a special challenge». J. Nutr. 137. PMID 17374687.
- [Prasad 2003] Prasad, A. S. (2003). «Zinc deficiency». British Medical Journal 326. DOI:10.1136/bmj.326.7386.409. PMID 12595353.
- [encyclo.co.uk] ^ Spelter. Encyclo. Проверено 1 августа 2009.
- [CRC 2006] ^ 1 2 3 4 CRC contributors (2006). David R. Lide Handbook of Chemistry and Physics, 87th, Boca Raton, Florida: CRC Press, Taylor & Francis Group, 4-41. ISBN 0849304873.
- [Heiserman 1992] ^ Heiserman, David L. (1992). “Element 30: Zinc”, Exploring Chemical Elements and their Compounds. New York: TAB Books. ISBN 083063018X.
- [Lehto 1968] ^ 1 2 3 Lehto, R. S. (1968). “Zinc”, Clifford A. Hampel The Encyclopedia of the Chemical Elements. New York: Reinhold Book Corporation, 822–830. LCCN 68-29938. ISBN 0442155980.
- [Scoffern 1861] ^ Scoffern, John (1861). The Useful Metals and Their Alloys. Houlston and Wright, 591–603. Retrieved on 2009-04-06.
- [galvanizeit.org] ^ 1 2 Zinc Metal Properties. American Galvanizers Association (2008). Проверено 15 февраля 2009.
- [Ingalls 1902] ^ Ingalls, Walter Renton (1902). Production and Properties of Zinc: A Treatise on the Occurrence and Distribution of Zinc Ore, the Commercial and Technical Conditions Affecting the Production of the Spelter, Its Chemical and Physical Properties and Uses in the Arts, Together with a Historical and Statistical Review of the Industry. The Engineering and Mining Journal, 142–146.
- [Emsley 2001] ^ 1 2 3 4 Emsley, John (2001). “Zinc”, Nature's Building Blocks: An A-Z Guide to the Elements. Oxford, England, UK: Oxford University Press, 499–505. ISBN 0198503407.
- [Greenwood 1997] ^ 1 2 3 Greenwood, N. N., Earnshaw, A. (1997). Chemistry of the Elements, 2nd, Oxford: Butterworth-Heinemann. ISBN 0750633654.
- [usgs.gov 2009] ^ 1 2 Tolcin, A. C. Mineral Commodity Summaries 2009: Zinc (PDF). United States Geological Survey (2009). Проверено 25 ноября 2008.
- [Cohen 2007] ^ Cohen, David (2007). «Earth audit». New Scientist 194. DOI:10.1016/S0262-4079(07)61315-3.
- [idtechex.com] ^ Augsberg University Calculate When Our Materials Run Out. IDTechEx (2007-06-04). Проверено 9 декабря 2008.
- [Gordon 2006] ^ Gordon, R. B.; Bertram, M.; Graedel, T. E. (2006). «Metal stocks and sustainability». Proceedings of the National Academy of Sciences 103. DOI:10.1073/pnas.0509498103. PMID 16432205.
- [Broadley 2007] ^ 1 2 3 Broadley, M. R.; White, P. J.; Hammond, J. P.; Zelko I.; Lux A. (2007). «Zinc in plants». New Phytologist 173. DOI:10.1111/j.1469-8137.2007.01996.x. PMID 17286818.
- [Prasad 2008] ^ Prasad A. S. (2008). «Zinc in human health: effect of zinc on immune cells». Mol. Med. 14. DOI:10.2119/2008-00033.Prasad. PMID 18385818.
- [Sugarman 1983] ^ Zinc's role in microorganisms is particularly reviewed in: Sugarman B (1983). «Zinc and infection». Review of Infectious Diseases 5. PMID 6338570.
- [NRC 2000] ^ United States National Research Council, Institute of Medicine. (2000). Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academies Press, 442–455.
- [Cotton 1999] ^ Cotton, F. Albert, Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999). Advanced Inorganic Chemistry, 6th, New York: John Wiley & Sons, Inc. ISBN 04711999575.
- [Rink 2000] ^ Rink, L. (2000). «Zinc and the immune system». Proc Nutr Soc 59. DOI:10.1017/S0029665100000781. PMID 11115789.
- [Wapnir 1990] ^ Wapnir, Raul A. (1990). Protein Nutrition and Mineral Absorption. Boca Raton, Florida: CRC Press. ISBN 0849352274.
- [Berdanier 2007] ^Berdanier, Carolyn D., Dwyer, Johanna T.; Feldman, Elaine B. (2007). Handbook of Nutrition and Food. Boca Raton, Florida: CRC Press. ISBN 0849392187.
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