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= = Production = =
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Europium is associated with the other rare earth elements and is , therefore , mined together with them . Separation of the rare earth elements is a step in the later processing . Rare earth elements are found in the minerals bastnäsite , loparite , xenotime , and monazite in mineable quantities . The first two are or... |
4 ( Ln denotes a mixture of all the lanthanides except promethium ) , and the third is a fluorocarbonate LnCO3F . Monazite also contains thorium and yttrium , which complicates handling because thorium and its decay products are radioactive . For the extraction from the ore and the isolation of individual lanthanides ... |
A few large deposits produce or produced a significant amount of the world production . The Bayan Obo iron ore deposit contains significant amounts of bastnäsite and monazite and is , with an estimated 36 million tonnes of rare earth element oxides , the largest known deposit . The mining operations at the Bayan Obo d... |
= = Compounds = =
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Europium compounds tend to exist trivalent oxidation state under most conditions . Commonly these compounds feature Eu ( III ) bound by 6 – 9 oxygenic ligands , typically water . These compounds , the chlorides , sulfates , nitrates , are soluble in water or polar organic solvent . Lipophilic europium complexes often ... |
= = = Halides = = =
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Europium metal reacts with all the halogens :
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2 Eu + 3 X2 → 2 EuX3 ( X = F , Cl , Br , I )
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This route gives white europium ( III ) fluoride ( EuF3 ) , yellow europium ( III ) chloride ( EuCl3 ) , gray europium ( III ) bromide ( EuBr3 ) , and colorless europium ( III ) iodide ( EuI3 ) . Europium also forms the corresponding dihalides : yellow @-@ green europium ( II ) fluoride ( EuF2 ) , colorless europium (... |
= = = Chalcogenides and pnictides = = =
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Europium forms stable compounds with all of the chalcogens , but the heavier chalcogens ( S , Se , and Te ) stabilize the lower oxidation state . Three oxides are known : europium ( II ) oxide ( EuO ) , europium ( III ) oxide ( Eu2O3 ) , and the mixed @-@ valence oxide Eu3O4 , consisting of both Eu ( II ) and Eu ( III... |
Eu2O3 + 3 H2S → 2 EuS + 3 H2O + S
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The main nitride is europium ( III ) nitride ( EuN ) .
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= = History of study = =
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Although europium is present in most of the minerals containing the other rare elements , due to the difficulties in separating the elements it was not until the late 1800s that the element was isolated . William Crookes observed the phosphorescent spectra of the rare elements and observed spectral lines later assigne... |
Europium was first found in 1890 by Paul Émile Lecoq de Boisbaudran , who obtained basic fractions from samarium @-@ gadolinium concentrates which had spectral lines not accounted for by samarium or gadolinium . However , the discovery of europium is generally credited to French chemist Eugène @-@ Anatole Demarçay , w... |
When the europium @-@ doped yttrium orthovanadate red phosphor was discovered in the early 1960s , and understood to be about to cause a revolution in the color television industry , there was a scramble for the limited supply of europium on hand among the monazite processors , as the typical europium content in monaz... |
Frank Spedding , celebrated for his development of the ion @-@ exchange technology that revolutionized the rare earth industry in the mid @-@ 1950s , once related the story of how he was lecturing on the rare earths in the 1930s when an elderly gentleman approached him with an offer of a gift of several pounds of euro... |
= = Applications = =
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Relative to most other elements , commercial applications for europium are few and rather specialized . Almost invariably , they exploit its phosphorescence , either in the + 2 or + 3 oxidation state .
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It is a dopant in some types of glass in lasers and other optoelectronic devices . Europium oxide ( Eu2O3 ) is widely used as a red phosphor in television sets and fluorescent lamps , and as an activator for yttrium @-@ based phosphors . Color TV screens contain between 0 @.@ 5 and 1 g of europium oxide . Whereas triv... |
An application that has almost fallen out of use with the introduction of affordable superconducting magnets is the use of europium complexes , such as Eu ( fod ) 3 , as shift reagents in NMR spectroscopy . Chiral shift reagents , such as Eu ( hfc ) 3 , are still used to determine enantiomeric purity .
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A recent ( 2015 ) application of europium is in quantum memory chips which can reliably store information for days at a time ; these could allow sensitive quantum data to be stored to a hard disk @-@ like device and shipped around the country .
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= = Precautions = =
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There are no clear indications that europium is particularly toxic compared to other heavy metals . Europium chloride , nitrate and oxide have been tested for toxicity : europium chloride shows an acute intraperitoneal LD50 toxicity of 550 mg / kg and the acute oral LD50 toxicity is 5000 mg / kg . Europium nitrate sho... |
= North @-@ Eastern Area Command ( RAAF ) =
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North @-@ Eastern Area Command was one of several geographically based commands raised by the Royal Australian Air Force ( RAAF ) during World War II . For most of its existence it covered central and northern Queensland , and Papua New Guinea . It was formed in January 1942 from the eastern part of the former Norther... |
= = History = =
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= = = World War II = = =
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North @-@ Eastern Area Command was formed at Townsville , Queensland , on 15 January 1942 , taking over the eastern portion of what was previously Northern Area Command . Northern Area had been established on 8 May 1941 as one of the RAAF 's geographically based command @-@ and @-@ control zones , and covered northern... |
The outbreak of the Pacific War in December 1941 was the catalyst for Northern Area being split into North @-@ Western Area ( NWA ) and North @-@ Eastern Area ( NEA ) , to counter distinct threats to Northern Australia and New Guinea , respectively . Air Commodore Frank Lukis , formerly in charge of Northern Area , wa... |
No. 33 Squadron , operating ex @-@ Qantas Short Empire flying boats and several smaller transports , was raised in NEA on 19 February 1942 . Earlier that month , Lukis warned higher command of the poor state of preparedness and low morale of Australian Army troops at Port Moresby , due to lack of air cover and apparen... |
Several USAAF bomber formations operated under NEA 's control in early 1942 , including A @-@ 24 Banshees of the 8th Squadron from Port Moresby , and B @-@ 17 Flying Fortresses of the 435th Squadron ( initially known as the " Kangaroo Squadron " ) from Townsville . As of 20 April , operational authority over all RAAF ... |
NEA 's operational headquarters , a reinforced concrete bunker known as Building 81 , was completed in May 1942 . Located on Green Street , Townsville , at the base of Castle Hill , it was topped with a suburban house to mislead enemy aircraft . The same month , Eastern Area Command was formed , taking control of unit... |
On 1 September 1942 , No. 9 ( Operational ) Group was formed at Port Moresby as a mobile strike force to move forward with Allied advances in the Pacific , in contrast to the static , defensive nature of the area commands . It took over all units in New Guinea previously operating under NEA Command . NEA initially ret... |
In early 1943 , Japan was still believed to be capable of invading , or at least bombing , the Torres Strait islands , and NEA had only No. 7 Squadron , now operating from Horn Island , to counter the threat . It was reinforced in April by No. 84 Squadron , flying CAC Boomerang fighters . The same month , No. 72 Wing ... |
Cobby served as AOC NEA until November 1943 , handing over to Air Commodore John Summers , who held command for the remainder of the war . By the end of November , NEA headquarters staff numbered 499 , including ninety @-@ seven officers . NEA 's Catalinas joined aircraft of No. 9 Group in support of the US invasion o... |
= = = Post @-@ war activity and disbandment = = =
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Following the end of the Pacific War in August 1945 , SWPA was dissolved and RAAF Headquarters again assumed full control of all its operational formations , including the area commands . By the end of the month , NEA headquarters staff numbered 526 , including ninety @-@ eight officers . The Air Force shrank dramatic... |
Commencing in October 1953 , the RAAF was reorganised from a geographically based command @-@ and @-@ control system into one based on function . In February 1954 , the newly constituted functional organisations — Home , Training , and Maintenance Commands — assumed control of all operations , training and maintenance... |
As of 2009 , the former NEA headquarters in Building 81 , Green Street , housed Townsville 's State Emergency Service group .
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= = Order of battle = =
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As at 30 April 1942 , NEA 's order of battle comprised :
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RAAF Station Townsville
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No. 24 ( General Purpose ) Squadron
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No. 33 ( Transport ) Squadron
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No. 76 ( Fighter ) Squadron
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RAAF Station Amberley
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No. 23 ( General Purpose ) Squadron
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RAAF Station Port Moresby
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No. 11 ( General Reconnaissance ) Squadron
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No. 20 ( General Reconnaissance ) Squadron
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No. 32 ( General Reconnaissance ) Squadron
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No. 75 ( Fighter ) Squadron
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No. 3 Fighter Sector Headquarters , Townsville
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No. 4 Fighter Sector Headquarters , Port Moresby
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= Cape lobster =
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The Cape lobster , Homarinus capensis , is a species of small lobster that lives off the coast of South Africa , from Dassen Island to Haga Haga . Only a few dozen specimens are known , mostly regurgitated by reef @-@ dwelling fish . It lives in rocky reefs , and is thought to lay large eggs that have a short larval p... |
= = Distribution and ecology = =
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The Cape lobster is endemic to South Africa . It occurs from Dassen Island , Western Cape in the west to Haga Haga , Eastern Cape in the east , a range of 900 kilometres ( 560 mi ) . Most of the known specimens were regurgitated by fish caught on reefs at depths of 20 – 40 metres ( 66 – 131 ft ) . This suggests that t... |
= = Description = =
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Homarinus capensis is considerably smaller than the large northern lobsters of the Atlantic Ocean , Homarus gammarus ( the European lobster ) and Homarus americanus ( the American lobster ) , at 8 – 10 centimetres ( 3 @.@ 1 – 3 @.@ 9 in ) total length , or 4 – 5 cm ( 1 @.@ 6 – 2 @.@ 0 in ) carapace length . Accounts o... |
Homarinus and Homarus are considered to be the most plesiomorphic genera in the family Nephropidae . Nonetheless , the Cape lobster differs from Homarus in a number of characters . The rostrum of the Cape lobster is flattened , while that of Homarus is rounded in section , and curves upwards at the tip . The three pai... |
= = Taxonomy and evolution = =
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Cape lobsters are elusive and rare , with only fourteen specimens having been collected between 1792 ( the date of its first description ) and 1992 . These include five males in the collections of the South African Museum ( Cape Town ) , two in the Natural History Museum ( London ) , one in each of the East London Mus... |
The Cape lobster was first described by Johann Friedrich Wilhelm Herbst in 1792 as Cancer ( Astacus ) capensis . It was independently described in 1793 by Johan Christian Fabricius as Astacus flavus , possibly based on the same type specimen . When Friedrich Weber erected the genus Homarus in 1795 , he included Fabric... |
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