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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 This process is now known as Van Arkel–de Boer process. However, in 1937 De Boer and Evert Verwey reported that many transition-metal oxides (such as NiO) with a partially filled d-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ruinen
Ruinen is a village in the Dutch province of Drenthe. It is located in the municipality of De Wolden, about 10 km northwest of Hoogeveen. The Dwingelderveld National Park is located near Ruinen. History The village was first mentioned in 1139 as de Runa. The etymology is unknown. Ruinen is an ''esdorp'' from the Early Middle Ages. Around 1140, a double monastery of the Benedictines was founded in Ruinen, however they moved to De Wijk in 1325. The Dutch Reformed has been built in the 15th century replacing and reusing the monastery church of which dated from around 1140. The tower was built in 1423. The spire has been renewed in 1660 after it had been damaged by a storm, and the crown was replaced in 1952. Between 1972 and 1975, the church was restored to its original form before 1836. Ruinen was home to 1,059 people in 1840. Ruinen was a separate municipality until 1998, when it became part of De Wolden. The windmill A windmill is a machine operated by the force o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium
Hafnium is a chemical element; it has 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 1922, by Dirk Coster and George de Hevesy. 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 the neutron-transparent corrosion-resistant zirconium alloys used in nuclear r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People From De Wolden
The term "the people" refers to the public or common mass of people of a polity. As such it is a concept of human rights law, international law as well as constitutional law, particularly used for claims of popular sovereignty. In contrast, a people is any plurality of persons considered as a whole. Used in politics and law, the term "a people" refers to the collective or community of an ethnic group or nation. Concepts Legal Chapter One, Article One of the Charter of the United Nations states that "peoples" have the right to self-determination. Though the mere status as peoples and the right to self-determination, as for example in the case of Indigenous peoples (''peoples'', as in all groups of indigenous people, not merely all indigenous persons as in ''indigenous people''), does not automatically provide for independent sovereignty and therefore secession. Indeed, judge Ivor Jennings identified the inherent problems in the right of "peoples" to self-determination, as i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1971 Deaths
* The year 1971 had three partial solar eclipses (Solar eclipse of February 25, 1971, February 25, Solar eclipse of July 22, 1971, July 22 and Solar eclipse of August 20, 1971, August 20) and two total lunar eclipses (February 1971 lunar eclipse, February 10, and August 1971 lunar eclipse, August 6). The world population increased by 2.1% this year, the highest increase in history. Events January * January 2 – 1971 Ibrox disaster: During a crush, 66 people are killed and over 200 injured in Glasgow, Scotland. * January 5 – The first ever One Day International cricket match is played between Australia and England at the Melbourne Cricket Ground. * January 8 – Tupamaros kidnap Geoffrey Jackson, British ambassador to Uruguay, in Montevideo, keeping him captive until September. * January 9 – Uruguayan president Jorge Pacheco Areco demands emergency powers for 90 days due to kidnappings, and receives them the next day. * January 12 – The landmark United States televis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1899 Births
Events January * January 1 ** Spanish rule formally ends in Cuba with the cession of Spanish sovereignty to the U.S., concluding 400 years of the Spanish Empire in the Americas.''The American Monthly Review of Reviews'' (February 1899), pp. 153-157 ** In Samoa, followers of Mataafa, claimant to the rule of the island's subjects, burn the town of Upolu in an ambush of followers of other claimants, Malietoa Tanus and Tamasese, who are evacuated by the British warship HMS ''Porpoise''. ** Queens and Staten Island become administratively part of New York City. * January 2 – Theodore Roosevelt is inaugurated as Governor of New York at the age of 39. * January 3 – A treaty of alliance is signed between Russia and Afghanistan. * January 5 – **A fierce battle is fought between American troops and Filipino defenders at the town of Pililla on the island of Luzon. *The collision of a British steamer and a French steamer kills 12 people on the English Channel. * Jan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Netherlands Academy Of Arts And Sciences
The Royal Netherlands Academy of Arts and Sciences (, KNAW) is an organization dedicated to the advancement of science and literature in the Netherlands. The academy is housed in the Trippenhuis in Amsterdam. In addition to various advisory and administrative functions it operates a number of research institutes and awards many prizes, including the Lorentz Medal in theoretical physics, the Dr Hendrik Muller Prize for Behavioural and Social Science and the Heineken Prizes. Main functions The academy advises the Dutch government on scientific matters. While its advice often pertains to genuine scientific concerns, it also counsels the government on such topics as policy on careers for researchers or the Netherlands' contribution to major international projects. The academy offers solicited and unsolicited advice to parliament, ministries, universities and research institutes, funding agencies and international organizations. * Advising the government on matters related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal–insulator Transition
Metal–insulator transitions are transitions of a material from a metal (material with good electrical conductivity of electric charges) to an insulator (material where conductivity of charges is quickly suppressed). These transitions can be achieved by tuning various ambient parameters such as temperature, pressure or, in case of a semiconductor, doping. History The basic distinction between metals and insulators was proposed by Hans Bethe, Arnold Sommerfeld and Felix Bloch in 1928-1929. It distinguished between conducting metals (with partially filled bands) and nonconducting insulators. However, in 1937 Jan Hendrik de Boer and Evert Verwey reported that many transition-metal oxides (such as NiO) with a partially filled d-band were poor conductors, often insulating. In the same year, the importance of the electron-electron correlation was stated by Rudolf Peierls. Since then, these materials as well as others exhibiting a transition between a metal and an insulator hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition-metal Oxides
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinide elements (the f-block) are called inner transition metals and are sometimes considered to be transition metals as well. They are lustrous metals with good electrical and thermal conductivity. Most (with the exception of group 11 and group 12) are hard and strong, and have high melting and boiling temperatures. They form compounds in any of two or more different oxidation states and bind to a variety of ligands to form coordination complexes that are often coloured. They form many useful alloys and are often employed as catalysts in elemental form or in compounds such as coordination complexes and oxides. Most are strongly paramagnetic because of their unpaired d electrons, as are many of their compounds. All of the elements that are ferro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evert Verwey
Evert Johannes Willem Verwey, also Verweij, (April 30, 1905 in Amsterdam – February 13, 1981 in Utrecht) was a Dutch chemist, who also did research in physical chemistry. Verwey studied chemistry at the University of Amsterdam and obtained his MSc () in 1929. From 1931 he worked as an assistant at the University of Groningen, where he obtained his PhD under the guidance of Hugo Rudolph Kruyt (1934, ''cum laude''). In 1934 he moved to the Philips Laboratories in Eindhoven. He continued work on colloids, which was also the topic of his dissertation, and on oxides. The Verwey transition in magnetite is named after him. Some of his studies on transition metal oxides (carried out jointly with Jan Hendrik de Boer) showed that some transition-metal oxides had electrical properties that could not be explained on the basis of band theory. Between 1946 and 1967, together with physicist Hendrik Casimir and the engineer Herre Rinia, he was director of the Laboratories. He is known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iodine
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a violet gas at . The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek , meaning 'violet'. Iodine occurs in many oxidation states, including iodide (I−), iodate (), and the various periodate anions. As the heaviest essential mineral nutrient, iodine is required for the synthesis of thyroid hormones. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. The dominant producers of iodine today are Chile and Japan. Due to its high atomic number and ease of attachment to organic compounds, it has also found favour as a non-toxic radiocontrast material. Because of the spec ... [...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 categor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
