| Related sites for http://en.wikipedia.org/wiki/Tantalum |
| Visual_Elements__Seaborgium Physical information, ionisation energies, and key isotopes. | | WebElements__Seaborgium Information on history, isolation, and properties. | | Wikipedia__Seaborgium History and basic information on the element. | | CAC-2004 9th Conference on Chemometrics in Analytical Chemistry: "New Challenges for a Maturing Science". Lisbon, Portugal; 20--23 September 2004. | | COCHEM\'03 Nonlinear phenomena in computational chemical physics. Barcelona, Spain; 9--14 June 2003. | | DIMACS_Workshop_on_Discrete_Mathematical_Chemistry DIMACS, Rutgers University; 23--25 March 1998. Proceedings can be ordered. | | Effective_Theories_for_Materials_and_Macromolecules Workshop in research session on Mathematics of Materials and Macromolecules, IMA, Minnesota, USA; 8--11 June 2005. | | First_Indo-US_Workshop_on_Mathematical_Chemistry With Applications in Molecular Design and Hazard Assessment of Chemicals. Visva-Bharati University, Santiniketan, West Bengal; 9--13 January 1998. | | MaThCryst Crystallography at the start of the 21st century: Mathematical and Symmetry Aspects. A satellite meeting of the XXII European Crystallographic Meeting (ECM-22). Budapest, Hungary; 24--26 August 200 | | Mathematics_in_Chemical_Kinetics_and_Engineering_(MACKIE-2002) An international workshop to be held in Ghent, Belgium; 5--8 May 2002. | | Second_Indo-US_Workshop_on_Mathematical_Chemistry With Applications to Drug Discovery, Environmental Toxicology, Cheminformatics and Bioinformatics. Duluth, Minnesota, 30 May -- 3 June 2000. | | Third_Indo-US_Workshop With applications to Drug Discovery, Environmental Toxicology, Cheminformatics and Bioinformatics. New Delhi, India. Duluth, Minnesota, USA; 2--7 August 2003. | | ChemicalElements_com__Titanium Basic information, atomic structure, and isotopes. | | EnvironmentalChemistry_com__Titanium Atomic structure, chemical and physical properties, and table of nuclides. | | It\'s_Elemental__Titanium Basic physical and historical information. | | LANL__Titanium History, sources, uses, and properties. | | Lenntech__Titanium Physical data, chemical properties, and health effects. | | Titanium Data tables and historic information. | | USGS_Minerals_Information__Titanium Statistics and information on the worldwide supply, demand, and flow of the element (PDF format). | | Visual_Elements__Titanium Image, general and physical information, source, uses, key isotopes, and ionisation energies. | | WebElements__Titanium Extensive information on history, uses, occurrence, compounds, and properties of the element. | | Wikipedia__Titanium Properties of the element, including its history, applications, and characteristics. | | Radiochemistry_of_Titanium Full text of the monograph by Vincent J. Landis (San Diego State University, San Diego, California). [PDF] (January, 1971) | | ChemicalElements_com__Potassium Basic information, atomic structure, and isotopes. | | EnvironmentalChemistry_com__Potassium Atomic structure, chemical and physical properties, and table of nuclides. | | It\'s_Elemental__Potassium Basic physical and historical information. | | LANL__Potassium Sources, uses, properties, and isotopes. | | Lenntech__Potassium Physical data, chemical properties, and health effects. | | Potassium Data tables and historic information. | | Visual_Elements__Potassium Image, animation, source, uses, physical information, and key isotopes. | | WebElements__Potassium Extensive information on history, uses, occurrence, compounds, and properties of the element. | | Wikipedia__Potassium Properties of the element, including its history, applications, and characteristics. | | Radiochemistry_of_Potassium Full text of the monograph by William T. Mullins and G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] (November, 1961) | | ChemicalElements_com__Tellurium Basic information, atomic structure, and table of isotopes. | | EnvironmentalChemistry_com__Tellurium Atomic structure, chemical and physical properties, and table of nuclides. | | It\'s_Elemental__Tellurium Basic physical and historical information. | | LANL__Tellurium Sources, properties, handling, and uses. | | Lenntech__Tellurium Physical data, chemical properties, health and environmental effects. | | Tellurium Data tables and historic information. | | Visual_Elements__Tellurium General and physical information, source, uses, key isotopes, and ionisation energies. |
|
Tantalum - Wikipedia, the free encyclopedia /**/ /**/ if (wgNotice != '') document.writeln(wgNotice); Tantalum From Wikipedia, the free encyclopedia Jump to: navigation, search 73hafnium ← tantalum → tungstenNb↑Ta↓Db Periodic Table - Extended Periodic TableGeneralName, Symbol, Numbertantalum, Ta, 73Element categorytransition metalsGroup, Period, Block5, 6, dAppearancegray blue Standard atomic weight180.94788(2) g·mol−1Electron configuration[Xe] 4f14 5d3 6s2Electrons per shell2, 8, 18, 32, 11, 2Physical propertiesPhasesolidDensity (near r.t.)16.69 g·cm−3Liquid density at m.p.15 g·cm−3Melting point3290 K(3017 °C, 5463 °F)Boiling point5731 K(5458 °C, 9856 °F)Heat of fusion36.57 kJ·mol−1Heat of vaporization732.8 kJ·mol−1Specific heat capacity(25 °C) 25.36 J·mol−1·K−1Vapor pressureP(Pa)1101001 k10 k100 kat T(K)329735973957439549395634Atomic propertiesCrystal structurecubic body centeredOxidation states5, 4, 3 (mildly acidic oxide)Electronegativity1.5 (Pauling scale)Ionization energies1st: 761 kJ/mol2nd: 1500 kJ/molAtomic radius145 pmAtomic radius (calc.)200 pmCovalent radius138 pmMiscellaneousMagnetic orderingno dataElectrical resistivity(20 °C) 131 n Ω·mThermal conductivity(300 K) 57.5 W·m−1·K−1Thermal expansion(25 °C) 6.3 µm·m−1·K−1Speed of sound (thin rod)(20 °C) 3400 m/sYoung's modulus186 GPaShear modulus69 GPaBulk modulus200 GPaPoisson ratio0.34Mohs hardness6.5Vickers hardness873 MPaBrinell hardness800 MPaCAS registry number7440-25-7Most-stable isotopesMain article: Isotopes of tantalumisoNAhalf-lifeDMDE (MeV)DP177Tasyn56.56 hε1.166177Hf178Tasyn2.36 hε1.910178Hf179Tasyn1.82 aε0.110179Hf180Tasyn8.125 hε0.854180Hf180Tasyn8.125 hβ-0.708180W180mTa0.012%>1.2×1015 y(not observed)ε0.929180Hfβ-0.783180WIT0.075180Ta181Ta99.988%181Ta is stable with 108 neutrons182Tasyn114.43 dβ-1.814182W183Tasyn5.1 dβ-1.070183WReferencesTantalum (pronounced /ˈtæntələm/) (formerly tantalium /tænˈtæliəm/) is a chemical element with the symbol Ta and atomic number 73. A rare, hard, blue-grey, lustrous, transition metal, tantalum is highly corrosion-resistant and occurs naturally in the mineral tantalite, always together with the chemically similar niobium. The chemical inertness of tantalum made it a valuable substance for laboratory equipment and substitute for platinum, but its main use today is in tantalum capacitors. The exploitation of coltan, a tantalum ore, in the conflict regions of the Congo raised ethical questions and human rights issues, and endangered wildlife.Contents1 History2 Characteristics2.1 Chemical2.2 Compounds2.3 Isotopes2.4 Occurrence3 Production4 Applications4.1 Electronics4.2 Alloys4.3 Other use5 Precautions6 References7 External links//[edit] HistoryTantalum was discovered in Sweden in 1802 by Anders Ekeberg and isolated in 1820 by Jöns Berzelius. Many contemporary chemists believed niobium and tantalum were the same elements until 1844 and later 1866 when researchers showed that niobic and tantalic acids were different compounds. Early investigators were only able to isolate impure metal and the first relatively pure ductile metal was produced by Werner von Bolton in 1903. Wires made with tantalum metal were used for light bulbs until tungsten replaced it. [1]Its name is derived from the character Tantalus, father of Niobe in Greek mythology, who was punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him - if he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp.[2] Ekeberg wrote "This metal I call tantalum … partly in allusion to its incapacity, when immersed in acid, to absorb any and be saturated."[3]For many years, the commercial technology for separating tantalum from niobium involved the fractional crystallization of potassium heptafluorotantalate away from potassium oxypentafluoroniobate monohydrate, that had been discovered by Jean Charles Galissard de Marignac in the 1866. The method has been supplanted by solvent extraction from fluoride-containing solutions.[4][edit] CharacteristicsTantalum is dark, dense, ductile, very hard, easily fabricated, and highly conductive of heat and electricity. The metal is renowned for its resistance to corrosion by acids; in fact, at temperatures below 150 °C tantalum is almost completely immune to attack by the normally aggressive aqua regia. It can be dissolved with hydrofluoric acid or acidic solutions containing the fluoride ion and sulfur trioxide, as well as with a solution of potassium hydroxide. Tantalum's high melting point of 3017 °C (boiling point 5458 °C) is exceeded only by tungsten and rhenium for metals, and carbon.[edit] ChemicalSee also: Category:Niobium compoundsIt is able to form oxides with the oxidation states +5 (Ta2O5) and +4 (TaO2),[5] The most stable oxidation state is +5, tantalum pentoxide.[5] Tantalum pentoxide is the starting material for several tantalum compounds. The compounds are created by dissolving the pentoxide in basic hydroxide solutions or by melting it in another metal oxide. Such examples are lithium tantalate (LiTaO3) and lanthan tantalate (LaTaO4). In the lithium tantalate, the tantalate ion TaO3− is not alone, but part of a perovskite-like structure; while the lantane niobate contains lone TaO43− ions.[5]The fluorides of tantalum can be used for its separation from niobium.[6] Tantalum forms halogen compounds in the oxidation states of +5, +4, and +3 of the type TaX5, TaX4, and TaX3, although multi core complexes and substoichiometric compounds are also known.[5][7] Tantalum pentafluoride (TaF5) is a white solid with a melting point of 97.0 °C and tantalum pentachloride (TaCl5) is a white solid with a melting point of 247.4 °C. Tantalum pentachloride is hydrolyzed by water and react with additional tantalum at elevated temperatures by forming the black and highly hygroscopic tantalum tetrachloride (TaCl4). While the trihalogen compounds can be obtained by reduction of the pentahalogenes with hydrogen, the dihalogen compounds do not exist.[5][edit] CompoundsSee also tantalum compounds. Please help improve this article or section by expanding it. Further information might be found on the talk page. (January 2008)Los Alamos National Laboratory scientists have developed a tantalum carbide-graphite composite material that is one of the hardest materials ever synthesized. Korean researchers have developed an amorphous tantalum-tungsten-copper alloy which is more flexible and two to three times stronger than traditional steel alloys.[8]There are two tantalum aluminides, TaAl3 and Ta3Al; they are stable, refractory and reflective, and have been proposed [9] as mirror coatings for use in the IR. Tantalum carbide, like the more commonly used tungsten carbide, is a very hard ceramic used in cutting tools. Tantalum (III) nitride is used as a thin film insulator in some microelectronic fabrication processes.[edit] IsotopesMain article: isotopes of tantalumNatural tantalum consists of two isotopes: 180mTa (0.012%) and 181Ta (99.988%). 181Ta is a stable isotope. 180mTa (m denotes a metastable state) is predicted to decay in three ways: isomeric transition to the ground state of 180Ta, beta decay to 180W, or electron capture to 180Hf. However, any radioactivity of this nuclear isomer was never observed. Only a lower limit on its half life of over 1015 years has been set. The ground state of 180Ta has a half life of only 8 hours.180mTa is the only naturally occurring nuclear isomer (excluding radiogenic and cosmogenic short-living nuclides). It is also the rarest isotope in the Universe, taking into account the elemental abundance of tantalum and isotopic abundance of 180mTa in the natural mixture of isotopes.Tantalum has been proposed as a "salting" material for nuclear weapons (cobalt is another, better-known salting material). A jacket of 181Ta, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 182Ta with a half-life of 114.43 days and produce approximately 1.12 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several months. Such a weapon is not known to have ever been built, tested, or used.[10][edit] Occurrence  Tantalite, Pilbarra district, AustraliaTantalum is estimated to make up about 1 ppm[11] or 2 ppm[7]of the Earth's crust by weight.There are many species of tantalum minerals, only some of which are so far being used by industry as raw materials: tantalite, microlite, wodginite, euxenite, polycrase. Tantalite [(Fe,Mn) Ta2O6] is the most important mineral for tantalum extraction.Other minerals include samarskite and fergusonite.The main production of tantalum occurs in Australia, where the largest producer, Talison Minerals (formerly part of the Sons of Gwalia company), operates the Wodgina mine.[12] Tantalum minerals are also mined in Brazil, Canada, China, Ethiopia and Mozambique. Tantalum is also produced in Thailand and Malaysia as a by-product of tin mining and smelting.Future large sources of supply, in order of magnitude, are being explored in Saudi Arabia, Egypt, Greenland, China, Mozambique, Canada, Australia, U.S.A., Finland and Brazil.[13]A comprehensive, 2002 review of non-Australian mines is available[14].Tantalite has the same mineral structure as columbite [(Fe,Mn) (Ta,Nb)2O6]; when there is more Ta than Nb it is called tantalite and when there is more Nb than Ta is it called columbite (or niobite). In central Africa the colloquial term coltan is used to refer to the two minerals equally, an example being the Democratic Republic of the Congo which the United States Geological Survey reports in its 2006 yearbook as having produced a little less than 1% of the world's tantalum for the past four years.[15]Ethical questions have been raised about responsible corporate behaviour, human rights and endangered wildlife, due to the exploitation of resources such as coltan in the conflict regions of the Congo.[16] According to United Nations report[17] smuggling and exportation of coltan helped fuel the war in the Congo, a crisis that has resulted in approximately 5.4 million[18] deaths since 1998 – making it the world’s deadliest documented conflict since World War II.[edit] ProductionSeveral complicated steps are involved in the extraction of tantalum from tantalite, the first being crushing of the mineral and physical concentration by gravity separation which is generally carried out near the mine site. Further processing by chemical separation is generally accomplished by treating the ores with a mixture of hydrofluoric acid and sulfuric acids at over 90°C. This causes the tantalum and niobium to dissolve as complex fluorides and be separated from the impurities.Ta2O5 + 14HF → 2H2[TaF7] + 5H2ONb2O5 + 10HF → 2H2[NbOF5] + 3H2OThe first industrial scale separation, developed by de Marignac, used the difference in solubility between the complex niobium and tantalum fluorides, dipotassium oxypentafluoroniobate monohydrate (K2[NbOF5].H2O) and dipotassium heptafluorotantalate (K2[TaF7]) in water. Newer processes use the liquid extraction of the fluorides from aqueous solution by organic solvents like cyclohexanone.[6] The complex niobium and tantalum fluorides are extracted separately from the organic solvent with water and either precipitated by the addition of potassium fluoride to produce a potassium fluoride complex, or precipitated with ammonia as the pentoxide:[5]H2[TaF7] + KF → K2[TaF7]↓ + HF2H2[TaF7] + 14NH4OH → Ta2O5↓ + 14NH47 + 9H2OThe resulting potassium fluorotantalate salt is generally treated by reduction with molten sodium to produce a coarse tantalum powder.[19][edit] Applications[edit] Electronics Tantalum electrolytic capacitorThe major use for tantalum, as the metal powder, is in the production of electronic components, mainly capacitors and some high-power resistors[20]. Tantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum powder, pressed into a pellet shape, as one "plate" of the capacitor, the oxide as the dielectric, and an electrolytic solution or conductive solid as the other "plate". Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume. Because of the size and weight advantages, tantalum capacitors are attractive for portable telephones, pagers, personal computers, and automotive electronics.[21][edit] AlloysTantalum is also used to produce a variety of alloys that have high melting points, are strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of superalloys for jet engine components, chemical process equipment, nuclear reactors, and missile parts. Because of its ductility, tantalum can be drawn into fine wires or filaments, which are used for evaporating metals such as Aluminium.[21][22]Due to the fact that it resists attack by body fluids and is nonirritating, tantalum is widely used in making surgical instruments and implants. For example, porous tantalum coatings are used in the construction of orthopedic implants due to tantalum's ability to form a direct bond to hard tissue.[23][edit] Other useThe oxide is used to make special high refractive index glass for camera lenses. The metal is also used to make vacuum furnace parts.Shaped charge and explosively formed penetrator liners have been constructed from tantalum.[edit] PrecautionsCompounds containing tantalum are rarely encountered in the laboratory. The metal is highly biocompatible and is used for body implants and coatings, therefore attention may be focused on other elements or the physical nature of the chemical compound.[24]The only concern in the laboratory with tantalum is with the powder form: as is common with finely divided metal powders this may catch fire.A single study from 1956 (Oppenheimer, B.S., Oppenheimer, E.T., Danishefsky, I. & Stout, A.P. (1956) Carcinogenic effects of metals in rodent. Cancer Res., 16, 439-441) is the only reference in literature ever linking tantalum to local sarcomas. It is possible the result was due to other factors not considered in the study. The study was quoted in IARC Monograph vol. 74 which includes the following "Note to the reader": "Inclusion of an agent in the Monographs does not imply that it is a carcinogen, only that the published data have been examined."[25][edit] References^ "Scanning Our Past from London The Filament Lamp and New Materials". Proceedings of the IEEE 89 (3). 2001. doi:10.1109/5.915382. ^ Aycan, Mugla, Sule (2005). "Chemistry Education and Mythology". Journal of Social Sciences 1 (4): 238–239. ^ Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), Oxford: Butterworth-Heinemann, p. 1138, ISBN 0-7506-3365-4 ^ Gupta, C. K.; Suri, A. K. (1994). Extractive Metallurgy of Niobium, CRC Press. ISBN 0849360714. ^ a b c d e f Holleman, A. F., Wiberg, E., Wiberg, N. (2007). Lehrbuch der Anorganischen Chemie, 102nd ed., de Gruyter. ISBN 978-3-11-017770-1. ^ a b Soisson, Donald J.; McLafferty, J. J.; Pierret, James A. (1961). "Staff-Industry Collaborative Report: Tantalum and Niobium". Ind. Eng. Chem. 53 (11): 861–868. doi:10.1021/ie50623a016. ^ a b Agulyansky, Anatoly (2004). The Chemistry of Tantalum and Niobium Fluoride Compounds, Elsevier. ISBN 9780444516046, http://books.google.de/books?id=Z-4QXNB5Hp8C. Retrieved on 2 September 2008. ^ Digital Chosunilbo (English Edition) : Daily News in English About Korea^ [1]^ Win, David Tin; Masum, Md. Al (2003). Weapons of Mass Destruction. 6. pp. 199–219, http://www.journal.au.edu/au_techno/2003/apr2003/aujt6-4_article07.pdf. ^ Emsley, John (2001). "Tantalum". Nature's Building Blocks: An A-Z Guide to the Elements. Oxford, England, UK: Oxford University Press. pp.420. ISBN 0198503407. ^ Talison Minerals (2008), Wodgina Operations, http://www.talison.com.au/pages/wodgina.htm, retrieved on 3 June 2008 ^ Mining Journal, MJ (2007-November), Tantalum supplement, http://www.noventa.net/pdf/presentations/tanatalumSCR_presentation.pdf, retrieved on 3 June 2008 ^ GSWA Mineral Resources Bulletin 22, Chapter 10: International tantalum resources — exploration and mining^ US Geological Survey (2006), 2006 Minerals Yearbook Nb & Ta, http://minerals.usgs.gov/minerals/pubs/commodity/niobium/#pubs, retrieved on 3 June 2008 ^ Hayes, Karen; Burge, Richard. Coltan Mining in the Democratic Republic of Congo: How tantalum-using industries can commit to the reconstruction of the DRC. 1–64. ISBN 1903703107. ^ S/2003/1027, 2003-10-26, http://www.un.org/Docs/journal/asp/ws.asp?m=S/2003/1027, retrieved on 19 April 2008 ^ International Rescue Committee, Special Report: Congo, http://www.theirc.org/special-report/congo-forgotten-crisis.html, retrieved on 19 April 2008 ^ T.I.C., Extraction/refining, http://www.tanb.org/tantalum1.html, retrieved on 3 June 2008 ^ What is a resistor?^ a b "Commodity Report 2008: Tantalum". United States Geological Survey. Retrieved on 2008-10-24.^ Buckman Jr., R. W. (2000). "New applications for tantalum and tantalum alloys". JOM Journal of the Minerals, Metals and Materials Society 52 (3): 40–41. doi:10.1007/s11837-000-0100-6. ^ Cohen, R. (2006). "Applications of porous tantalum in total hip arthroplasty". Journal of the American Academy of Orthopaedic Surgeons 14: 646–655. ^ Biomaterials (2001), Biocompatibility of tantalum, http://www.ncbi.nlm.nih.gov/pubmed/11336297, retrieved on 3 June 2008 ^ IARC (1999), Surgical implants and other foreign bodies, http://www.inchem.org/documents/iarc/vol74/implants.html, retrieved on 3 June 2008 [edit] External links Look up tantalum inWiktionary, the free dictionary. Wikimedia Commons has media related to: TantalumWebElements.com - TantalumTantalum-Niobium International Study CenterLos Alamos National Laboratory - TantalumT.I.C. industry site - Tantalum uses, ore mining and extractionTantalum - Raw Materials and Processingv • d • ePeriodic tableH HeLiBe BCNOFNeNaMg AlSiPSClArKCa ScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSr YZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgUubUutUuqUupUuhUusUuoUueUbn Alkali metalsAlkaline earth metalsLanthanoidsActinoidsTransition metalsOther metalsMetalloidsOther nonmetalsHalogensNoble gasesRetrieved from "http://en.wikipedia.org/wiki/Tantalum" Categories: Chemical elements | Transition metals | TantalumHidden categories: Articles to be expanded since January 2008 | All articles to be expanded Views Article Discussion Edit this page History Personal tools Log in / create account if (window.isMSIE55) fixalpha(); Navigation Main page Contents Featured content Current events Random article Search Interaction About Wikipedia Community portal Recent changes Contact Wikipedia Donate to Wikipedia Help Toolbox What links here Related changesUpload fileSpecial pages Printable version Permanent linkCite this page Languages Afrikaans العربية Azərbaycan বাংলা Беларуская Bosanski Български Català Česky Corsu Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Furlan Gaelg Galego 한국어 Հայերեն Hrvatski Ido Bahasa Indonesia Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ Kiswahili Kreyòl ayisyen Kurdî / كوردی Latina Latviešu Lëtzebuergesch Lietuvių Lojban Magyar മലയാളം Nāhuatl Nederlands 日本語 Norsk (bokmål) Norsk (nynorsk) Occitan Polski Português Română Русский Shqip Sicilianu Simple English Slovenčina Slovenščina Српски / Srpski Srpskohrvatski / Српскохрватски Suomi Svenska ไทย Tiếng Việt Türkçe Українська 中文   This page was last modified on 1 December 2008, at 02:48. All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.) Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity. Privacy policy About Wikipedia Disclaimers if (window.runOnloadHook) runOnloadHook(); |
|
