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Although coal, hydrocarbons, iron ore, platinum, copper, chromium, nickel, gold and other minerals have been found, they have not been in large enough quantities to exploit. The 1991 Protocol on Environmental Protection to the Antarctic Treaty also restricts a struggle for resources. In 1998, a compromise agreement was... |
This large collection of meteorites allows a better understanding of the abundance of meteorite types in the solar system and how meteorites relate to asteroids and comets. New types of meteorites and rare meteorites have been found. Among these are pieces blasted off the Moon, and probably Mars, by impacts. These spec... |
In 2002 the Antarctic Peninsula's Larsen-B ice shelf collapsed. Between 28 February and 8 March 2008, about 570 km2 (220 sq mi) of ice from the Wilkins Ice Shelf on the southwest part of the peninsula collapsed, putting the remaining 15,000 km2 (5,800 sq mi) of the ice shelf at risk. The ice was being held back by a "t... |
Antarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a Terra Australis—a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa—had existed since the times of Ptolemy... |
About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km (1.0 mi) thick. The continent has about 90% of the world's ice (and thereby about 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 60 m (200 ft). In most of the interior of... |
There is some evidence, in the form of ice cores drilled to about 400 m (1,300 ft) above the water line, that Lake Vostok's waters may contain microbial life. The frozen surface of the lake shares similarities with Jupiter's moon, Europa. If life is discovered in Lake Vostok, it would strengthen the argument for the po... |
Africa separated from Antarctica in the Jurassic, around 160 Ma, followed by the Indian subcontinent in the early Cretaceous (about 125 Ma). By the end of the Cretaceous, about 66 Ma, Antarctica (then connected to Australia) still had a subtropical climate and flora, complete with a marsupial fauna. In the Eocene epoch... |
Antarctica is colder than the Arctic for three reasons. First, much of the continent is more than 3,000 m (9,800 ft) above sea level, and temperature decreases with elevation in the troposphere. Second, the Arctic Ocean covers the north polar zone: the ocean's relative warmth is transferred through the icepack and prev... |
Emilio Marcos Palma was the first person born south of the 60th parallel south (the continental limit according to the Antarctic Treaty), as well as the first one born on the Antarctic mainland, in 1978 at Base Esperanza, on the tip of the Antarctic Peninsula; his parents were sent there along with seven other families... |
About 1150 species of fungi have been recorded from Antarctica, of which about 750 are non-lichen-forming and 400 are lichen-forming. Some of these species are cryptoendoliths as a result of evolution under extreme conditions, and have significantly contributed to shaping the impressive rock formations of the McMurdo D... |
The Argentine, British and Chilean claims all overlap, and have caused friction. On 18 December 2012, the British Foreign and Commonwealth Office named a previously unnamed area Queen Elizabeth Land in tribute to Queen Elizabeth II's Diamond Jubilee. On 22 December 2012, the UK ambassador to Argentina, John Freeman, wa... |
There has been some concern over the potential adverse environmental and ecosystem effects caused by the influx of visitors. Some environmentalists and scientists have made a call for stricter regulations for ships and a tourism quota. The primary response by Antarctic Treaty Parties has been to develop, through their ... |
Researchers include biologists, geologists, oceanographers, physicists, astronomers, glaciologists, and meteorologists. Geologists tend to study plate tectonics, meteorites from outer space, and resources from the breakup of the supercontinent Gondwana. Glaciologists in Antarctica are concerned with the study of the hi... |
At Buya in Eritrea, one of the oldest hominids representing a possible link between Homo erectus and an archaic Homo sapiens was found by Italian scientists. Dated to over 1 million years old, it is the oldest skeletal find of its kind and provides a link between hominids and the earliest anatomically modern humans. It... |
The Scottish traveler James Bruce reported in 1770 that Medri Bahri was a distinct political entity from Abyssinia, noting that the two territories were frequently in conflict. The Bahre-Nagassi ("Kings of the Sea") alternately fought with or against the Abyssinians and the neighbouring Muslim Adal Sultanate depending ... |
The creation of modern-day Eritrea is a result of the incorporation of independent, distinct kingdoms and sultanates (for example, Medri Bahri and the Sultanate of Aussa) eventually resulting in the formation of Italian Eritrea. In 1947 Eritrea became part of a federation with Ethiopia, the Federation of Ethiopia and E... |
Excavations in and near Agordat in central Eritrea yielded the remains of an ancient pre-Aksumite civilization known as the Gash Group. Ceramics were discovered that were related to those of the C-Group (Temehu) pastoral culture, which inhabited the Nile Valley between 2500–1500 BC. Some sources dating back to 3500 BC.... |
The Aksumites erected a number of large stelae, which served a religious purpose in pre-Christian times. One of these granite columns, the obelisk of Aksum, is the largest such structure in the world, standing at 90 feet. Under Ezana (fl. 320–360), Aksum later adopted Christianity. In the 7th century, early Muslims fro... |
Eritrea is a member of the United Nations, the African Union, and is an observing member of the Arab League. The nation holds a seat on the United Nations' Advisory Committee on Administrative and Budgetary Questions (ACABQ). Eritrea also holds memberships in the International Bank for Reconstruction and Development, I... |
The kingdom is mentioned in the Periplus of the Erythraean Sea as an important market place for ivory, which was exported throughout the ancient world. Aksum was at the time ruled by Zoskales, who also governed the port of Adulis. The Aksumite rulers facilitated trade by minting their own Aksumite currency. The state a... |
In 1888, the Italian administration launched its first development projects in the new colony. The Eritrean Railway was completed to Saati in 1888, and reached Asmara in the highlands in 1911. The Asmara–Massawa Cableway was the longest line in the world during its time, but was later dismantled by the British in World... |
Following the adoption of UN Resolution 390A(V) in December 1950, Eritrea was federated with Ethiopia under the prompting of the United States. The resolution called for Eritrea and Ethiopia to be linked through a loose federal structure under the sovereignty of the Emperor. Eritrea was to have its own administrative a... |
Additionally, the Italian Eritrea administration opened a number of new factories, which produced buttons, cooking oil, pasta, construction materials, packing meat, tobacco, hide and other household commodities. In 1939, there were around 2,198 factories and most of the employees were Eritrean citizens. The establishme... |
Lions are said to inhabit the mountains of the Gash-Barka Region. There is also a small population of elephants that roam in some parts of the country. Dik-diks can also be found in many areas. The endangered African wild ass can be seen in Denakalia Region. Other local wildlife include bushbucks, duikers, greater kudu... |
Eritrea can be split into three ecoregions. To the east of the highlands are the hot, arid coastal plains stretching down to the southeast of the country. The cooler, more fertile highlands, reaching up to 3000m has a different habitat. Habitats here vary from the sub-tropical rainforest at Filfil Solomona to the preci... |
It is estimated that there are around 100 elephants left in Eritrea, the most northerly of East Africa's elephants. The endangered African wild dog (Lycaon pictus) was previously found in Eritrea, but is now deemed extirpated from the entire country. In Gash Barka, deadly snakes like saw-scaled viper are common. Puff a... |
Eritrea is a one-party state in which national legislative elections have been repeatedly postponed. According to Human Rights Watch, the government's human rights record is considered among the worst in the world. Most Western countries have accused the Eritrean authorities of arbitrary arrest and detentions, and of d... |
In an attempt at reform, Eritrean government officials and NGO representatives have participated in numerous public meetings and dialogues. In these sessions they have answered questions as fundamental as, "What are human rights?", "Who determines what are human rights?", and "What should take precedence, human or comm... |
In its 2014 Press Freedom Index, Reporters Without Borders ranked the media environment in Eritrea at the very bottom of a list of 178 countries, just below totalitarian North Korea. According to the BBC, "Eritrea is the only African country to have no privately owned news media", and Reporters Without Borders said of ... |
Even during the war, Eritrea developed its transportation infrastructure by asphalting new roads, improving its ports, and repairing war-damaged roads and bridges as a part of the Warsay Yika'alo Program. The most significant of these projects was the construction of a coastal highway of more than 500 km connecting Mas... |
Eritrea is a multilingual country. The nation has no official language, as the Constitution establishes the "equality of all Eritrean languages". However, Tigrinya serves as the de facto language of national identity. With 2,540,000 total speakers of a population of 5,254,000 in 2006, Tigrinya is the most widely spoken... |
Eritrea has achieved significant improvements in health care and is one of the few countries to be on target to meet its Millennium Development Goal (MDG) targets in health, in particular child health. Life expectancy at birth has increased from 39.1 in 1960 to 59.5 years in 2008, maternal and child mortality rates hav... |
Additionally, owing to its colonial history, cuisine in Eritrea features more Italian influences than are present in Ethiopian cooking, including more pasta and greater use of curry powders and cumin.The Italian Eritrean cuisine started to be practiced during the colonial times of the Kingdom of Italy, when a large num... |
The culture of Eritrea has been largely shaped by the country's location on the Red Sea coast. One of the most recognizable parts of Eritrean culture is the coffee ceremony. Coffee (Ge'ez ቡን būn) is offered when visiting friends, during festivities, or as a daily staple of life. During the coffee ceremony, there are tr... |
Eritrea (/ˌɛrᵻˈtreɪ.ə/ or /ˌɛrᵻˈtriːə/;, officially the State of Eritrea, is a country in East Africa. With its capital at Asmara, it is bordered by Sudan in the west, Ethiopia in the south, and Djibouti in the southeast. The northeastern and eastern parts of Eritrea have an extensive coastline along the Red Sea. The n... |
Eritrea's ethnic groups each have their own styles of music and accompanying dances. Amongst the Tigrinya, the best known traditional musical genre is the guaila. Traditional instruments of Eritrean folk music include the stringed krar, kebero, begena, masenqo and the wata (a distant/rudimentary cousin of the violin). ... |
During the Middle Ages, the Eritrea region was known as Medri Bahri ("sea-land"). The name Eritrea is derived from the ancient Greek name for Red Sea (Ἐρυθρὰ Θάλασσα Erythra Thalassa, based on the adjective ἐρυθρός erythros "red"). It was first formally adopted in 1890, with the formation of Italian Eritrea (Colonia Er... |
In 2010, a genetic study was conducted on the mummified remains of baboons that were brought back as gifts from Punt by the ancient Egyptians. Led by a research team from the Egyptian Museum and the University of California, the scientists used oxygen isotope analysis to examine hairs from two baboon mummies that had b... |
After the decline of Aksum, the Eritrean highlands were under the domain of Bahr Negash ruled by the Bahr Negus. The area was then known as Ma'ikele Bahr ("between the seas/rivers," i.e. the land between the Red Sea and the Mereb river). It was later renamed under Emperor Zara Yaqob as the domain of the Bahr Negash, th... |
In 1922, Benito Mussolini's rise to power in Italy brought profound changes to the colonial government in Italian Eritrea. After il Duce declared the birth of the Italian Empire in May 1936, Italian Eritrea (enlarged with northern Ethiopia's regions) and Italian Somaliland were merged with the just conquered Ethiopia i... |
When Emperor Haile Selassie unilaterally dissolved the Eritrean parliament and annexed the country in 1962, the Eritrean Liberation Front (ELF) waged an armed struggle for independence. The ensuing Eritrean War for Independence went on for 30 years against successive Ethiopian governments until 1991, when the Eritrean ... |
Disagreements following the war have resulted in stalemate punctuated by periods of elevated tension and renewed threats of war. The stalemate led the President of Eritrea to urge the UN to take action on Ethiopia with the Eleven Letters penned by the President to the United Nations Security Council. The situation has ... |
However, Eritrea still faces many challenges. Despite number of physicians increasing from only 0.2 in 1993 to 0.5 in 2004 per 1000 population, this is still very low. Malaria and tuberculosis are common in Eritrea. HIV prevalence among the 15–49 group exceeds 2%. The fertility rate is at about 5 births per woman. Mate... |
Traditional Eritrean attire is quite varied among the ethnic groups of Eritrea. In the larger cities, most people dress in Western casual dress such as jeans and shirts. In offices, both men and women often dress in suits. Traditional clothing for Christian Tigrinya-speaking highlanders consists of bright white gowns c... |
Football and cycling are the most popular sports in Eritrea. In recent years, Eritrean athletes have also seen increasing success in the international arena. Zersenay Tadese, an Eritrean athlete, currently holds the world record in half marathon distance running. The Tour of Eritrea, a multi-stage international cycling... |
During the last interglacial period, the Red Sea coast of Eritrea was occupied by early anatomically modern humans. It is believed that the area was on the route out of Africa that some scholars suggest was used by early humans to colonize the rest of the Old World. In 1999, the Eritrean Research Project Team composed ... |
At the end of the 16th century, the Aussa Sultanate was established in the Denkel lowlands of Eritrea. The polity had come into existence in 1577, when Muhammed Jasa moved his capital from Harar to Aussa (Asaita) with the split of the Adal Sultanate into Aussa and the Sultanate of Harar. At some point after 1672, Aussa... |
In the vacuum that followed the 1889 death of Emperor Yohannes II, Gen. Oreste Baratieri occupied the highlands along the Eritrean coast and Italy proclaimed the establishment of the new colony of Italian Eritrea, a colony of the Kingdom of Italy. In the Treaty of Wuchale (It. Uccialli) signed the same year, King Menel... |
In the 1950s, the Ethiopian feudal administration under Emperor Haile Selassie sought to annex Eritrea and Italian Somaliland. He laid claim to both territories in a letter to Franklin D. Roosevelt at the Paris Peace Conference and at the First Session of the United Nations. In the United Nations, the debate over the f... |
The Eritrean highway system is named according to the road classification. The three levels of classification are: primary (P), secondary (S), and tertiary (T). The lowest level road is tertiary and serves local interests. Typically they are improved earth roads which are occasionally paved. During the wet seasons thes... |
According to recent estimates, 50% of the population adheres to Christianity, Islam 48%, while 2% of the population follows other religions including traditional African religion and animism. According to a study made by Pew Research Center, 63% adheres to Christianity and 36% adheres to Islam. Since May 2002, the gove... |
Education in Eritrea is officially compulsory between seven and 13 years of age. However, the education infrastructure is inadequate to meet current needs. Statistics vary at the elementary level, suggesting that between 65 and 70% of school-aged children attend primary school; Approximately 61% attend secondary school... |
A typical traditional Eritrean dish consists of injera accompanied by a spicy stew, which frequently includes beef, kid, lamb or fish. Overall, Eritrean cuisine strongly resembles those of neighboring Ethiopia, Eritrean cooking tend to feature more seafood than Ethiopian cuisine on account of their coastal location. Er... |
Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium. Other uses of depleted uranium include counterwei... |
The discovery and isolation of radium in uranium ore (pitchblende) by Marie Curie sparked the development of uranium mining to extract the radium, which was used to make glow-in-the-dark paints for clock and aircraft dials. This left a prodigious quantity of uranium as a waste product, since it takes three tonnes of ur... |
The X-10 Graphite Reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, formerly known as the Clinton Pile and X-10 Pile, was the world's second artificial nuclear reactor (after Enrico Fermi's Chicago Pile) and was the first reactor designed and built for continuous operation. Argonne National Labor... |
Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is the 51st element in order of abundance in the Earth's crust. Uranium is also the highest-numbered element to be found naturally in significant quantities on Earth and is almost always found combined wit... |
Uranium-235 was the first isotope that was found to be fissile. Other naturally occurring isotopes are fissionable, but not fissile. On bombardment with slow neutrons, its uranium-235 isotope will most of the time divide into two smaller nuclei, releasing nuclear binding energy and more neutrons. If too many of these n... |
In nature, uranium(VI) forms highly soluble carbonate complexes at alkaline pH. This leads to an increase in mobility and availability of uranium to groundwater and soil from nuclear wastes which leads to health hazards. However, it is difficult to precipitate uranium as phosphate in the presence of excess carbonate at... |
It is estimated that 5.5 million tonnes of uranium exists in ore reserves that are economically viable at US$59 per lb of uranium, while 35 million tonnes are classed as mineral resources (reasonable prospects for eventual economic extraction). Prices went from about $10/lb in May 2003 to $138/lb in July 2007. This has... |
A team led by Enrico Fermi in 1934 observed that bombarding uranium with neutrons produces the emission of beta rays (electrons or positrons from the elements produced; see beta particle). The fission products were at first mistaken for new elements of atomic numbers 93 and 94, which the Dean of the Faculty of Rome, Or... |
The interactions of carbonate anions with uranium(VI) cause the Pourbaix diagram to change greatly when the medium is changed from water to a carbonate containing solution. While the vast majority of carbonates are insoluble in water (students are often taught that all carbonates other than those of alkali metals are i... |
Uranium is more plentiful than antimony, tin, cadmium, mercury, or silver, and it is about as abundant as arsenic or molybdenum. Uranium is found in hundreds of minerals, including uraninite (the most common uranium ore), carnotite, autunite, uranophane, torbernite, and coffinite. Significant concentrations of uranium ... |
Natural uranium consists of three major isotopes: uranium-238 (99.28% natural abundance), uranium-235 (0.71%), and uranium-234 (0.0054%). All three are radioactive, emitting alpha particles, with the exception that all three of these isotopes have small probabilities of undergoing spontaneous fission, rather than alpha... |
An additional 4.6 billion tonnes of uranium are estimated to be in sea water (Japanese scientists in the 1980s showed that extraction of uranium from sea water using ion exchangers was technically feasible). There have been experiments to extract uranium from sea water, but the yield has been low due to the carbonate p... |
Many contemporary uses of uranium exploit its unique nuclear properties. Uranium-235 has the distinction of being the only naturally occurring fissile isotope. Uranium-238 is fissionable by fast neutrons, and is fertile, meaning it can be transmuted to fissile plutonium-239 in a nuclear reactor. Another fissile isotope... |
A person can be exposed to uranium (or its radioactive daughters, such as radon) by inhaling dust in air or by ingesting contaminated water and food. The amount of uranium in air is usually very small; however, people who work in factories that process phosphate fertilizers, live near government facilities that made or... |
The most common forms of uranium oxide are triuranium octoxide (U 3O 8) and UO 2. Both oxide forms are solids that have low solubility in water and are relatively stable over a wide range of environmental conditions. Triuranium octoxide is (depending on conditions) the most stable compound of uranium and is the form mo... |
The use of uranium in its natural oxide form dates back to at least the year 79 CE, when it was used to add a yellow color to ceramic glazes. Yellow glass with 1% uranium oxide was found in a Roman villa on Cape Posillipo in the Bay of Naples, Italy, by R. T. Gunther of the University of Oxford in 1912. Starting in the... |
On 2 December 1942, as part of the Manhattan Project, another team led by Enrico Fermi was able to initiate the first artificial self-sustained nuclear chain reaction, Chicago Pile-1. Working in a lab below the stands of Stagg Field at the University of Chicago, the team created the conditions needed for such a reactio... |
Uranium is used as a colorant in uranium glass producing orange-red to lemon yellow hues. It was also used for tinting and shading in early photography. The 1789 discovery of uranium in the mineral pitchblende is credited to Martin Heinrich Klaproth, who named the new element after the planet Uranus. Eugène-Melchior Pé... |
In nature, uranium is found as uranium-238 (99.2742%) and uranium-235 (0.7204%). Isotope separation concentrates (enriches) the fissionable uranium-235 for nuclear weapons and most nuclear power plants, except for gas cooled reactors and pressurised heavy water reactors. Most neutrons released by a fissioning atom of u... |
The major application of uranium in the military sector is in high-density penetrators. This ammunition consists of depleted uranium (DU) alloyed with 1–2% other elements, such as titanium or molybdenum. At high impact speed, the density, hardness, and pyrophoricity of the projectile enable the destruction of heavily a... |
The discovery of the element is credited to the German chemist Martin Heinrich Klaproth. While he was working in his experimental laboratory in Berlin in 1789, Klaproth was able to precipitate a yellow compound (likely sodium diuranate) by dissolving pitchblende in nitric acid and neutralizing the solution with sodium ... |
Uranium ore is mined in several ways: by open pit, underground, in-situ leaching, and borehole mining (see uranium mining). Low-grade uranium ore mined typically contains 0.01 to 0.25% uranium oxides. Extensive measures must be employed to extract the metal from its ore. High-grade ores found in Athabasca Basin deposit... |
Two major types of atomic bombs were developed by the United States during World War II: a uranium-based device (codenamed "Little Boy") whose fissile material was highly enriched uranium, and a plutonium-based device (see Trinity test and "Fat Man") whose plutonium was derived from uranium-238. The uranium-based Littl... |
In 2005, seventeen countries produced concentrated uranium oxides, with Canada (27.9% of world production) and Australia (22.8%) being the largest producers and Kazakhstan (10.5%), Russia (8.0%), Namibia (7.5%), Niger (7.4%), Uzbekistan (5.5%), the United States (2.5%), Argentina (2.1%), Ukraine (1.9%) and China (1.7%)... |
During the Cold War between the Soviet Union and the United States, huge stockpiles of uranium were amassed and tens of thousands of nuclear weapons were created using enriched uranium and plutonium made from uranium. Since the break-up of the Soviet Union in 1991, an estimated 600 short tons (540 metric tons) of highl... |
Salts of many oxidation states of uranium are water-soluble and may be studied in aqueous solutions. The most common ionic forms are U3+ (brown-red), U4+ (green), UO+ 2 (unstable), and UO2+ 2 (yellow), for U(III), U(IV), U(V), and U(VI), respectively. A few solid and semi-metallic compounds such as UO and US exist for ... |
Some organisms, such as the lichen Trapelia involuta or microorganisms such as the bacterium Citrobacter, can absorb concentrations of uranium that are up to 300 times the level of their environment. Citrobacter species absorb uranyl ions when given glycerol phosphate (or other similar organic phosphates). After one da... |
Uranium metal heated to 250 to 300 °C (482 to 572 °F) reacts with hydrogen to form uranium hydride. Even higher temperatures will reversibly remove the hydrogen. This property makes uranium hydrides convenient starting materials to create reactive uranium powder along with various uranium carbide, nitride, and halide c... |
Uranium carbides and uranium nitrides are both relatively inert semimetallic compounds that are minimally soluble in acids, react with water, and can ignite in air to form U 3O 8. Carbides of uranium include uranium monocarbide (UC), uranium dicarbide (UC 2), and diuranium tricarbide (U 2C 3). Both UC and UC 2 are form... |
To be considered 'enriched', the uranium-235 fraction should be between 3% and 5%. This process produces huge quantities of uranium that is depleted of uranium-235 and with a correspondingly increased fraction of uranium-238, called depleted uranium or 'DU'. To be considered 'depleted', the uranium-235 isotope concentr... |
Normal functioning of the kidney, brain, liver, heart, and other systems can be affected by uranium exposure, because, besides being weakly radioactive, uranium is a toxic metal. Uranium is also a reproductive toxicant. Radiological effects are generally local because alpha radiation, the primary form of 238U decay, ha... |
The gas centrifuge process, where gaseous uranium hexafluoride (UF 6) is separated by the difference in molecular weight between 235UF6 and 238UF6 using high-speed centrifuges, is the cheapest and leading enrichment process. The gaseous diffusion process had been the leading method for enrichment and was used in the Ma... |
Uranium is a chemical element with symbol U and atomic number 92. It is a silvery-white metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all its isotopes are unstable (with half-lives of the six na... |
Uranium metal reacts with almost all non-metal elements (with an exception of the noble gases) and their compounds, with reactivity increasing with temperature. Hydrochloric and nitric acids dissolve uranium, but non-oxidizing acids other than hydrochloric acid attack the element very slowly. When finely divided, it ca... |
During the later stages of World War II, the entire Cold War, and to a lesser extent afterwards, uranium-235 has been used as the fissile explosive material to produce nuclear weapons. Initially, two major types of fission bombs were built: a relatively simple device that uses uranium-235 and a more complicated mechani... |
Uranium was also used in photographic chemicals (especially uranium nitrate as a toner), in lamp filaments for stage lighting bulbs, to improve the appearance of dentures, and in the leather and wood industries for stains and dyes. Uranium salts are mordants of silk or wool. Uranyl acetate and uranyl formate are used a... |
In 1972, the French physicist Francis Perrin discovered fifteen ancient and no longer active natural nuclear fission reactors in three separate ore deposits at the Oklo mine in Gabon, West Africa, collectively known as the Oklo Fossil Reactors. The ore deposit is 1.7 billion years old; then, uranium-235 constituted abo... |
Uranium's average concentration in the Earth's crust is (depending on the reference) 2 to 4 parts per million, or about 40 times as abundant as silver. The Earth's crust from the surface to 25 km (15 mi) down is calculated to contain 1017 kg (2×1017 lb) of uranium while the oceans may contain 1013 kg (2×1013 lb). The c... |
Uranium-238 is the most stable isotope of uranium, with a half-life of about 4.468×109 years, roughly the age of the Earth. Uranium-235 has a half-life of about 7.13×108 years, and uranium-234 has a half-life of about 2.48×105 years. For natural uranium, about 49% of its alpha rays are emitted by each of 238U atom, and... |
Most ingested uranium is excreted during digestion. Only 0.5% is absorbed when insoluble forms of uranium, such as its oxide, are ingested, whereas absorption of the more soluble uranyl ion can be up to 5%. However, soluble uranium compounds tend to quickly pass through the body, whereas insoluble uranium compounds, es... |
Calcined uranium yellowcake, as produced in many large mills, contains a distribution of uranium oxidation species in various forms ranging from most oxidized to least oxidized. Particles with short residence times in a calciner will generally be less oxidized than those with long retention times or particles recovered... |
Appointments to the Order of the British Empire were at first made on the nomination of the self-governing Dominions of the Empire, the Viceroy of India, and the colonial governors, as well as on nominations from within the United Kingdom. As the Empire evolved into the Commonwealth, nominations continued to come from ... |
Any individual made a member of the Order for gallantry could wear an emblem of two crossed silver oak leaves on the same riband, ribbon or bow as the badge. It could not be awarded posthumously and was effectively replaced in 1974 with the Queen's Gallantry Medal. If recipients of the Order of the British Empire for G... |
Honorary knighthoods are appointed to citizens of nations where Queen Elizabeth II is not Head of State, and may permit use of post-nominal letters but not the title of Sir or Dame. Occasionally honorary appointees are, incorrectly, referred to as Sir or Dame - Bill Gates or Bob Geldof, for example. Honorary appointees... |
The Order has six officials: the Prelate; the Dean; the Secretary; the Registrar; the King of Arms; and the Usher. The Bishop of London, a senior bishop in the Church of England, serves as the Order's Prelate. The Dean of St Paul's is ex officio the Dean of the Order. The Order's King of Arms is not a member of the Col... |
Appointments to the Order of the British Empire were discontinued in those Commonwealth realms that established a national system of honours and awards such as the Order of Australia, the Order of Canada, and the New Zealand Order of Merit. In many of these systems, the different levels of award and honour reflect the ... |
The members of The Beatles were made MBEs in 1965. John Lennon justified the comparative merits of his investiture by comparing military membership in the Order: "Lots of people who complained about us receiving the MBE [status] received theirs for heroism in the war – for killing people… We received ours for entertain... |
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