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Anton Eduard Van Arkel
Anton Eduard van Arkel, (19 November 1893 – 14 March 1976) was a Dutch chemist. Van Arkel suggested the names " pnictogen" and "pnictide" to refer to chemical elements in group 15 (the nitrogen group or nitrogen family) of the periodic table. Van Arkel, together with Jan Hendrik de Boer, developed a method for the preparation of very pure tungsten: the dissociation of the vapor of tungsten chloride on an incandescent core wire known as the Van Arkel–de Boer process. This method was later used by himself and others for many other metals and non-metals. Van Arkel and de Boer thus provided the first method to fabricate pure titanium. Van Arkel became member of the Royal Netherlands Academy of Arts and Sciences in 1962. See also *Crystal bar process *Hafnium Hafnium is a chemical element with the Symbol (chemistry), symbol Hf and atomic number 72. A lustre (mineralogy), lustrous, silvery gray, tetravalence, tetravalent transition metal, hafnium chemically resembles zirco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Dirk Coster and George de Hevesy, making it the penultimate stable element to be discovered (the last being rhenium in 1925). Hafnium is named after , the Latin name for Copenhagen, where it was discovered. Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nanometers and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium's large neutron capture cross section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jan Hendrik De Boer
Jan Hendrik de Boer (19 March 1899 – 25 April 1971) was a Dutch physicist and chemist. De Boer was born in Ruinen, De Wolden, and died in The Hague. He studied at the University of Groningen and was later employed in industry. Together with Anton Eduard van Arkel, de Boer developed a chemical transport reaction for titanium, zirconium, and hafnium known as the crystal bar process. In a closed vessel the metal reacts with iodine at elevated temperature forming the iodide. At a tungsten filament of 1700 °C the reverse reaction occurs, and the iodine and the metal are set free. The metal forms a solid coating at the tungsten filament and the iodine can react with additional metal, resulting in a steady turnover. ::M + 2I2 (>400 °C) → MI4 ::MI4 (1700 °C) → M + 2I2 De Boer became a member of the Royal Netherlands Academy of Arts and Sciences in 1940, and foreign member in 1947. See also *Metal–insulator transition *Van Arkel–de Boer process The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Utrecht University Alumni
Utrecht ( , , ) is the fourth-largest city and a municipality of the Netherlands, capital and most populous city of the province of Utrecht. It is located in the eastern corner of the Randstad conurbation, in the very centre of mainland Netherlands, about 35 km south east of the capital Amsterdam and 45 km north east of Rotterdam. It has a population of 361,966 as of 1 December 2021. Utrecht's ancient city centre features many buildings and structures, several dating as far back as the High Middle Ages. It has been the religious centre of the Netherlands since the 8th century. It was the most important city in the Netherlands until the Dutch Golden Age, when it was surpassed by Amsterdam as the country's cultural centre and most populous city. Utrecht is home to Utrecht University, the largest university in the Netherlands, as well as several other institutions of higher education. Due to its central position within the country, it is an important hub for both rail and roa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People From 's-Gravenzande
A person ( : people) is a being that has certain capacities or attributes such as reason, morality, consciousness or self-consciousness, and being a part of a culturally established form of social relations such as kinship, ownership of property, or legal responsibility. The defining features of personhood and, consequently, what makes a person count as a person, differ widely among cultures and contexts. In addition to the question of personhood, of what makes a being count as a person to begin with, there are further questions about personal identity and self: both about what makes any particular person that particular person instead of another, and about what makes a person at one time the same person as they were or will be at another time despite any intervening changes. The plural form "people" is often used to refer to an entire nation or ethnic group (as in "a people"), and this was the original meaning of the word; it subsequently acquired its use as a plural form of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1976 Deaths
Events January * January 3 – The International Covenant on Economic, Social and Cultural Rights enters into force. * January 5 – The Pol Pot regime proclaims a new constitution for Democratic Kampuchea. * January 11 – The 1976 Philadelphia Flyers–Red Army game results in a 4–1 victory for the National Hockey League's Philadelphia Flyers over HC CSKA Moscow of the Soviet Union. * January 16 – The trial against jailed members of the Red Army Faction (the West German extreme-left militant Baader–Meinhof Group) begins in Stuttgart. * January 18 ** Full diplomatic relations are established between Bangladesh and Pakistan 5 years after the Bangladesh Liberation War. ** The Scottish Labour Party is formed as a breakaway from the UK-wide party. ** Super Bowl X in American football: The Pittsburgh Steelers defeat the Dallas Cowboys, 21–17, in Miami. * January 21 – First commercial Concorde flight, from London to Bahrain. * January 27 ** The United States vetoes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1893 Births
Events January–March * January 2 – Webb C. Ball introduces railroad chronometers, which become the general railroad timepiece standards in North America. * Mark Twain started writing Puddn'head Wilson. * January 6 – The Washington National Cathedral is chartered by Congress; the charter is signed by President Benjamin Harrison. * January 13 ** The Independent Labour Party of the United Kingdom has its first meeting. ** U.S. Marines from the ''USS Boston'' land in Honolulu, Hawaii, to prevent the queen from abrogating the Bayonet Constitution. * January 15 – The ''Telefon Hírmondó'' service starts with around 60 subscribers, in Budapest. * January 17 – Overthrow of the Kingdom of Hawaii: Lorrin A. Thurston and the Citizen's Committee of Public Safety in Hawaii, with the intervention of the United States Marine Corps, overthrow the government of Queen Liliuokalani. * January 21 ** The Cherry Sisters first perform in Marion, Iowa. ** The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Arkel–Ketelaar Triangle
Bond triangles or Van Arkel–Ketelaar triangles (named after Anton Eduard van Arkel and J. A. A. Ketelaar) are triangles used for showing different compounds in varying degrees of ionic, metallic and covalent bonding. History In 1941 Van Arkel recognised three extreme materials and associated bonding types. Using 36 main group elements, such as metals, metalloids and non-metals, he placed ionic, metallic and covalent bonds on the corners of an equilateral triangle, as well as suggested intermediate species. The bond triangle shows that chemical bonds are not just particular bonds of a specific type. Rather, bond types are interconnected and different compounds have varying degrees of different bonding character (for example, covalent bonds with significant ionic character are called polar covalent bonds). Six years later, in 1947, Ketelaar developed van Arkel's idea by adding more compounds and placing bonds on different sides of the triangle. Many people developed the tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium
Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine. Titanium was discovered in Cornwall, Kingdom of Great Britain, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titan (mythology), Titans of Greek mythology. The element occurs within a number of minerals, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere; it is found in almost all living things, as well as bodies of water, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll process, Kroll and Hunter process, Hunter processes. The most common compound, titanium dioxide, is a popular photocatalysis, photocatalyst and is used in the manufacture of white pigments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
's-Gravenzande
s-Gravenzande is a town in the province of South Holland, in the Netherlands. It is a part of the municipality of Westland, and lies about southwest of The Hague. Until 2004 it was a separate municipality and covered an area of 20.77 km2 (of which 3.38 km2 water). The town of 's-Gravenzande had 15,241 inhabitants in 2011. The built-up area of the town was 2.7 km2, and contained 5,879 residences.Statistics Netherlands (CBS)''Bevolkingskernen in Nederland 2001''. (Statistics are for the continuous built-up area). The statistical area "'s-Gravenzande", which also can include the peripheral parts of the village, as well as the surrounding countryside, has a population of around 119,750.Statistics Netherlands (CBS)''Statline: Kerncijfers wijken en buurten 2003-2005'' As of 1 January 2005. As of 1 January 2009, 's-Gravenzande is the largest town in Westland with 19.428 inhabitants. The former municipality of 's-Gravenzande also included the township of Heenweg. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Netherlands
) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherlands , established_title2 = Act of Abjuration , established_date2 = 26 July 1581 , established_title3 = Peace of Münster , established_date3 = 30 January 1648 , established_title4 = Kingdom established , established_date4 = 16 March 1815 , established_title5 = Liberation Day , established_date5 = 5 May 1945 , established_title6 = Kingdom Charter , established_date6 = 15 December 1954 , established_title7 = Caribbean reorganisation , established_date7 = 10 October 2010 , official_languages = Dutch , languages_type = Regional languages , languages_sub = yes , languages = , languages2_type = Recognised languages , languages2_sub = yes , languages2 = , demonym = Dutch , capital = Amsterdam , largest_city = capital , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Bar Process
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macroscopic single crystals are usually identifiable by their geometrical shape, consisting of flat faces with specific, characteristic orientations. The scientific study of crystals and crystal formation is known as crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. The word ''crystal'' derives from the Ancient Greek word (), meaning both " ice" and " rock crystal", from (), "icy cold, frost". Examples of large crystals include snowflakes, diamonds, and table salt. Most inorganic solids are not crystals but polycrystals, i.e. many microscopic crystals fused together into a single solid. Polycrystals include most metals, rocks, ceramics, and ice. A third cat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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