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Ytterbium is a chemical element with the symbol Yb and atomic number 70. It is the fourteenth and penultimate element in the lanthanide series, the basis of the relative stability of its +2 oxidation state. However, like the other lanthanides, its most common oxidation state is +3, as in its oxide and other compounds. In aqueous solution, like compounds of other late lanthanides, soluble ytterbium compounds form complexes with nine water molecules; because of its closed-shell electron configuration, its density and melting and boiling points differ from those of most other lanthanides. In 1878, the Swiss chemist Jean Charles Galissard de Marignac separated from the rare earth "erbia" another independent component, which he called "ytterbia", for Ytterby, the village in Sweden near where he found the new component of erbium, he suspected that ytterbia was a compound of a new element that he called "ytterbium". In 1907, the new earth "lutecia" was separated from ytterbia, from which the element "lutecium" was extracted by Georges Urbain, Carl Auer von Welsbach, Charles James.

After some discussion, Marignac's name "ytterbium" was retained. A pure sample of the metal was not obtained until 1953. At present, ytterbium is used as a dopant of stainless steel or active laser media, less as a gamma ray source. Natural ytterbium is a mixture of seven stable isotopes, which altogether are present at concentrations of 3 parts per million; this element is mined in China, the United States and India in form of the minerals monazite and xenotime. The ytterbium concentration is low. Once extracted and prepared, ytterbium is somewhat hazardous as an skin irritant; the metal is a explosion hazard. Ytterbium is a soft and ductile chemical element that displays a bright silvery luster when pure, it is a rare earth element, it is dissolved by the strong mineral acids. It reacts with cold water and it oxidizes in air. Ytterbium has three allotropes labeled by the Greek letters alpha and gamma; the beta allotrope exists at room temperature, it has a face-centered cubic crystal structure. The high-temperature gamma allotrope has a body-centered cubic crystalline structure.

The alpha allotrope is stable at low temperatures. The beta allotrope has a metallic electrical conductivity at normal atmospheric pressure, but it becomes a semiconductor when exposed to a pressure of about 16,000 atmospheres, its electrical resistivity increases ten times upon compression to 39,000 atmospheres, but drops to about 10% of its room-temperature resistivity at about 40,000 atm. In contrast with the other rare-earth metals, which have antiferromagnetic and/or ferromagnetic properties at low temperatures, ytterbium is paramagnetic at temperatures above 1.0 kelvin. However, the alpha allotrope is diamagnetic. With a melting point of 824 °C and a boiling point of 1196 °C, ytterbium has the smallest liquid range of all the metals. Contrary to most other lanthanides, which have a close-packed hexagonal lattice, ytterbium crystallizes in the face-centered cubic system. Ytterbium has a density of 6.973 g/cm3, lower than those of the neighboring lanthanides and lutetium. Its melting and boiling points are significantly lower than those of thulium and lutetium.

This is due to the closed-shell electron configuration of ytterbium, which causes only the two 6s electrons to be available for metallic bonding and increases ytterbium's metallic radius. Ytterbium metal tarnishes in air. Finely dispersed ytterbium oxidizes in air and under oxygen. Mixtures of powdered ytterbium with polytetrafluoroethylene or hexachloroethane burn with a luminous emerald-green flame. Ytterbium reacts with hydrogen to form various non-stoichiometric hydrides. Ytterbium dissolves in water, but in acids, liberating hydrogen gas. Ytterbium is quite electropositive, it reacts with cold water and quite with hot water to form ytterbium hydroxide: 2 Yb + 6 H2O → 2 Yb3 + 3 H2 Ytterbium reacts with all the halogens: 2 Yb + 3 F2 → 2 YbF3 2 Yb + 3 Cl2 → 2 YbCl3 2 Yb + 3 Br2 → 2 YbBr3 2 Yb + 3 I2 → 2 YbI3 The ytterbium ion absorbs light in the near infrared range of wavelengths, but not in visible light, so ytterbia, Yb2O3, is white in color and the salts of ytterbium are colorless. Ytterbium dissolves in dilute sulfuric acid to form solutions that contain the colorless Yb ions, which exist as nonahydrate complexes: 2 Yb + 3 H2SO4 + 18 H2O → 2 3+ + 3 SO2−4 + 3 H2 Although trivalent, ytterbium forms divalent compounds.

This behavior is unusual for lanthanides, which exclusively form compounds with an oxidation state of +3. The +2 state has a valence electron configuration of 4f14 because the filled f-shell gives more stability; the yellow-green ytterbium ion is a strong reducing agent and decomposes water, releasing hydrogen gas, thus only the colorless ytterbium ion occurs in aqueous solution. Samarium and thulium behave this way in the +2 state

Warkworth Institution

The Warkworth Institution is a medium-security prison facility located in the municipality of Trent Hills, between the communities of Meyersburg and Warkworth. The prison is the largest federal correctional institution in Canada with a population of 625 housed in five units. Construction of Warkworth Institution started on March 26, 1965 on 208 acres of land, purchased by the Department of Justice. In 1967, the institution began operation with staff and no inmate population. In September 1967, ten blocks were opened and the first six inmates arrived from Joyceville Institution; the official opening took place on October 14, 1967. At the end of the 1968 fiscal year, the facility housed 92 inmates. In 1971, the Living Unit concept was introduced; the Warkworth prison, opened in 1967, lies just inside the Brighton border and is a major financial contributor to the municipality. The federal prison does not technically pay property taxes, but the government gives the amount in a grant to the municipality.

The Warkworth Institution gives Brighton $602,000 each year, 16 per cent of the municipality’s budget. The jail gives Northumberland County a grant of $168,500. A riot broke out at 9:00pm on July 21, 2009, during which prisoners took control of the prison infirmary. Subsequently, one inmate died of a drug overdose in his cell. Inmates broke the cement. By doing this inmates were able to get out of their cells; this can be seen. Warkworth is a sister institution to Springhill, NS. Correctional Service of Canada - Institutional Profiles - Ontario Region Sex Offender Characteristics, Response to Treatment, And Correctional Release Decisions At the Warkworth Sexual Behaviour Clinic

Akis Cleanthous

Akis Cleanthous was a Cypriot politician and financial analyst. Cleanhous served as the chairman of the Cyprus Stock Exchange from 2003 to 2007 and Minister of Education and Culture from 2007 until 2008, he was a member of a center-right political party. Cleanthous was born in 1964 in Paphos District, Cyprus, he received a bachelor's degree in marketing management from Baruch College in New York City. Cleanthous obtained a Master of Business Administration in quantitative analysis from St. John's University in Queens, New York. Cleanthous worked as banker, specializing in electronic banking, before moving into the Cypriot Internet Technology sector, he was appointed the chairman of the Cyprus Stock Exchange in 2003 by the Council of Ministers. He remained the head of the CSE until February 20, 2007, when he was appointed Minister of Education and Culture. In February 2007, Cleanthous was appointed the Minister of Education and Culture within the government of President Tassos Papadopoulos, he remained in that position until the Cypriot presidential election in February 2008, when he was succeeded as minister by Andreas Demetriou.

A former member of the House of Representatives of Cyprus for the DIKO, Cleanthous served as the head of the party's political planning bureau and a member of DIKO's executive committee. He served as the chairman of the Spyros Kyprianou Institute, a Cypriot think tank named for Spyros Kyprianou. Outside politics Cleanthous took a position as the managing director of Evresis Loyalty Management in 2008. Cleanthous served as the chairman of Sea Star Capital Plc and as a member of the board of directors of the Nicosia Chamber of Commerce and Industry. Akis Cleanthous died of a heart attack on April 11, 2011, at the age of 46. At the time of his death, Cleanthous had been scheduled to stand for election in the 2011 Cypriot legislative election on May 22, 2011. Cleanthous' funeral was held at the Saint Sophia Church in Strovolos. Dignitaries in attendance included Cypriot President Demetris Christofias, he was buried at St. Nicolaos cemetery. Cleanthous was survived by his wife, Christiana Cleanthous, son, Evangelos

Hymenachne amplexicaulis

Hymenachne amplexicaulis known as West Indian marsh grass in the US, Olive hymenachne in Australia, hereafter referred to as hymenachne, is New World species in the genus Hymenachne. Hymenachne is from the Greek hymen meaning "membrane" and achne meaning "chaff, scale" and amplexicaulis is from Latin "embracing the stem" or "stem-clasping; this freshwater species is native to the tropical and subtropical regions of the West Indies, Northern South America, Central America. Hymenachne is a perennial grass that reproduces via stolons; this robust species is found growing 1-2.5m tall. The stems are hairless and float prostrate across the top of the water grow upright from these bases to support leaves; the flat, triangular leaves auricles. The auricles help to distinguish it from other invasive wetland grasses and the native H. acutigluma in Australia. Hymenachne has been shown to increase the stem length between nodes to keep leaves above water during periods of flooding, its stem is packed with airy tissue called aerenchyma to help the stems float and to aid in flood tolerability.

Hymenachne flowers in the early fall and seeds in late fall. The flower is a panicle. Researchers at the University of Florida have seen multiple panicles per plant originating from branching at a single node. Hymenachne can produce thousands of seeds with up to 98% germination right off the panicle. Hymenachne prefers inundated soil and is known to survive comfortably in about a meter of water for 20 years; this species was shown to survive poorly in Australia. In its native range in Venezuela, in invaded areas of Florida, hymenachne was documented to survive in >1.2m of water for nearly a year. Hymenachne has been found in water greater than 4m deep persisting in floating mats dislodged after a storm event. Conversely, hymenachne is not recorded to survive sites that desiccate. Hymenachne is known to colonize and form dense monocultures in floodplains, roadside ditches, lake margins in invaded and native areas, it is found colonizing areas with little shading and competition from other species.

Although limited information is available on soil preferences of hymenachne, it has been found in deep, poorly drained muck soils in Florida. It is not found in waters with a significant salt concentration. There have been three introductions of hymenachne into Australia, one in Florida, one in Louisiana. Australia now lists hymenachne as one of the top twenty worst weeds. Hymenachne invasions have been shown to decrease species richness, increase invasive fish populations, overall cause fundamental changes in floral and faunal composition in Australia. Hymenachne was introduced in Australia as forage for cattle, for the same reason in Florida; the species was used in ponded pastures, or artificial ponds created to hold water for use in the dry season. High reproducibility from stem fragments aids in the invasion of this species; the first herbarium record of hymenachne in Florida is from 1957. The second specimen is not recorded until 1977; the cause for this gap is unknown.


Birtvisi is a ruined medieval fortress in Kvemo Kartli, nested within limestone cliffs in the Algeti river gorge. It is now within the boundaries of the Tetri-Tsqaro municipality, adjacent to the Algeti National Park, south-west of the nation's capital Tbilisi. Birtvisi is a natural rocky fortress of 1 km², secured by walls and towers, the most prominent of which – known as Sheupovari – tops the tallest rock in the area. Various accessory structures, an aqueduct included, have survived. In written sources, Birtvisi is first mentioned as a possession of the Arab amir of Tiflis of which he was divested by the Georgian nobles Liparit, Duke of Kldekari and Ivane Abazasdze in 1038. In medieval Georgia, Birtvisi entertained a reputation of an impregnable stronghold whose master could control the entire strategic Algeti gorge; the Turco-Mongol amir Timur notably reduced the fortress during one of his invasions of Georgia in 1403. After the partition of the Kingdom of Georgia in the 15th century, Birtvisi was within the borders of the Kingdom of Kartli and in possession of the princes Baratashvili

Angela Singer

Angela Singer is an artist of British and New Zealand nationality who lives in Wellington, New Zealand. An animal rights activist, she addresses the way in which people exploit animals and the environment through the repurposing and remodelling of vintage taxidermy, a process she calls "de-taxidermy". Since the 1990s her work has been exhibited both in New internationally. Singer graduated in 2002 from the Elam School of Fine Arts, University of Auckland with an MFA, she lives with artist Daniel Unverricht, in Wellington, New Zealand. Since the mid-1990s, Singer’s art has explored the human and non-human animal relationship, driven by her concern with the ethical and epistemological consequences of humans using non-human life, the role that humans play in the exploitation and destruction of animals and our environment. Singer sees the boundaries separating other species from humans as permeable, she sculpts in various media including modelling clay, fibre, ceramics and vintage jewelry, as well as wool and silk.

Many of her sculptural works combine mixed media with vintage taxidermy. Singer is known for working with vintage hunting trophy taxidermy, which she recycles into new sculptural forms to explore the human/animal divide, she calls this practice “de-taxidermy”, a process which involves revealing the wounds inflicted on the animal, wounds that are obscured by the taxidermy process and its attempted "rescue from time". Singer incorporates into her work some of the history of the death of the animal, which she obtains from those who give her the vintage taxidermy. Like Karen Knorr, Singer uses old hunting trophies or vintage taxidermy that natural history museums have thrown away; some of the trophy taxidermy Singer uses is found discarded in dumpsters and garbage piles. Curator Jo-Ann Conklin writes:A number of artists in the exhibition react to human treatment of animals and the environment. New Zealand artist and animal activist Angela Singer rails against trophy hunting, her latest work, depicts a decapitated deer with cartoony yet still gruesome bubble-gum pink “blood” spurting from it neck.

Mark Dion’s Concrete Jungle is…the detritus of our contemporary consumer culture — a pile of discards and garbage in which animals attempt to survive. Singer is an animal advocate. Like other artists such as Sue Coe, she is concerned with the ethics of using live animals in art, she will not have living creatures harmed or killed for her art. In the early 1990s she worked with the animal rights group Animal Liberation Victoria, Australia antivivisection campaign. A quote from Singer, regarding her use of taxidermy as an art form:I think using taxidermy is a way for me to honour the animals’ life, because all the taxidermy I use was once a trophy kill.... The idea of a trophy animal is sickening to me, she is not related to the animal rights activist and philosopher. Curious Creatures & Marvellous Monsters. Museum of New Zealand Te Papa Tongarewa, New Zealand. 18 Aug – 4 Nov 2018 The Sexual Politics of Meat. The Animal Museum, Los Angeles, USA. 25 Feb – 30 April 2017 Dead Animals, or the Curious Occurrence of Taxidermy in Contemporary Art.

David Winton Bell Gallery, List Art Center, Rhode Island, USA. 23 Jan – 27 Mar 2016 Ecce animalia. Museum of Contemporary Sculpture, Poland. 8 March – 15 June 2014 Points de vue d’artistes. Universcience Cité des sciences et de l’industrie, France. 23 September 2013 – 1 March 2014 Unnatural Natural History. Royal West of England Academy, Bristol, UK. 14 July – 23 Sept 2012 Controversy: The power of art. Mornington Peninsula Regional Gallery, Australia. 21 June – 12 Aug 2012 The Enchanted Forest. Strychnin Gallery, Germany, May 13 – 5 June, Musei Civici, Palazzo S. Francesco, Reggio Emilia, Italy, 17 June – 31 Aug 2011 Reconstructing the Animal. Plimsoll Gallery, University of Tasmania, Centre for Australia. 18 March – 15 April 2011 The Enchanted Palace. Cabinet of Curiosities. Kensington Palace, London. Mar–Nov, 2010 Creature Discomforts; the Suter Art Gallery Te Aratoi o Whakatū, Nelson, NZ. 13 May – 21 June 2009 The Idea of the Animal. Melbourne International Arts Festival. RMIT Gallery, RMIT University, Australia.

12 Aug – 18 Nov 2006 Animal Nature. Miller Gallery at Carnegie Mellon University, Pittsburgh, USA. 26 Aug – 2 Oct, 2005 Animality. Blue Oyster Art Project Space, New Zealand. 24 June – 5 July 2003 Mark Dion Maurizio Cattelan Annette Messager Modern Painters The Right Stuff article Antennae Journal of Nature in Visual Culture, UK. Issue 7, 2008. Death of the Animal. Angela Singer: Animal Rights and Wrongs. Giovanni Aloi "Animality: Cultural Constructions of the Animal" Blue Oyster Art Gallery and Project Space New Zealand Listener Second Nature review New Zealand Listener review Animality Art New Zealand review Insides Outsides The Independent. Fantasy fashion fit for a princess, The Enchanted Palace exhibition, Kensington Palace, London The Idea of the Animal 2006 Melbourne International Arts Festival Killing Animals. Eds; the Animal Studies Group Urbana and Chicago: University of Illinois Press. Animal Nature. Ed. J. Strayer Pittsburgh: Regina Gouger Miller Gallery, Carnegie Mellon University. ISBN 0-9772053-0-4 Angela Singer website The Criminal Animal Animal Nature