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Californium-252
Californium (98Cf) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 245Cf in 1950. There are 20 known radioisotopes ranging from 237Cf to 256Cf and one nuclear isomer, 249mCf. The longest-lived isotope is 251Cf with a half-life of 898 years. List of isotopes , - , rowspan=3, 237Cf , rowspan=3 style="text-align:right" , 98 , rowspan=3 style="text-align:right" , 139 , rowspan=3, 237.06207(54)# , rowspan=3, 2.1(3) s , SF , (various) , rowspan=3, 5/2+# , - , β+ , 237Bk , - , α , 233Cm , - , rowspan=3, 238Cf , rowspan=3 style="text-align:right" , 98 , rowspan=3 style="text-align:right" , 140 , rowspan=3, 238.06141(43)# , rowspan=3, 21.1(13) ms , SFLightest nuclide known to undergo spontaneous fission as the main decay mode , (various) , rowspan=3, 0+ , - , β+ (rare) , 238Bk , - , α (rare) , 234Cm , - , rowspan=2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Californium
Californium is a radioactive chemical element with the symbol Cf and atomic number 98. The element was first synthesized in 1950 at Lawrence Berkeley National Laboratory (then the University of California Radiation Laboratory), by bombarding curium with alpha particles ( helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all elements that have been produced in amounts large enough to see with the naked eye (after einsteinium). The element was named after the university and the U.S. state of California. Two crystalline forms exist for californium at normal pressure: one above and one below . A third form exists at high pressure. Californium slowly tarnishes in air at room temperature. Californium compounds are dominated by the +3 oxidation state. The most stable of californium's twenty known isotopes is californium-251, with a half-life of 898 years. This short half-life means the element is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radioisotope
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are energetic enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single nuclide the decay rate, and thus the half-life (''t''1/2) for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fission
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay. Nuclear fission of heavy elements was discovered on Monday 19 December 1938, by German chemist Otto Hahn and his assistant Fritz Strassmann in cooperation with Austrian-Swedish physicist Lise Meitner. Hahn understood that a "burst" of the atomic nuclei had occurred. Meitner explained it theoretically in January 1939 along with her nephew Otto Robert Frisch. Frisch named the process by analogy with biological fission of living cells. For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). Like nuclear fusion, for fission to produce energy, the total binding energy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mortar (weapon)
A mortar is usually a simple, lightweight, man-portable, muzzle-loaded weapon, consisting of a smooth-bore (although some models use a rifled barrel) metal tube fixed to a base plate (to spread out the recoil) with a lightweight bipod mount and a sight. They launch explosive shells (technically called bombs) in high-arcing ballistic trajectories. Mortars are typically used as indirect fire weapons for close fire support with a variety of ammunition. History Mortars have been used for hundreds of years. The earliest mortars were used in Korea in a 1413 naval battle when Korean gunsmiths developed the ''wan'gu'' (gourd-shaped mortar) (완구, 碗口). The earliest version of the ''wan'gu'' dates back to 1407. Choi Hae-san (최해산, 崔海山) (1380–1443), the son of Choe Mu-seon (최무선, 崔茂宣) (1325–1395), is generally credited with inventing the ''wan'gu''. In the Ming dynasty, general Qi Jiguang recorded the use of a mini cannon called the Hu dun pao that was simi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shell (projectile)
A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage sometimes includes large solid kinetic projectiles that is properly termed shot. Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used. All explosive- and incendiary-filled projectiles, particularly for mortars, were originally called ''grenades'', derived from the French word for pomegranate, so called because of the similarity of shape and that the multi-seeded fruit resembles the powder-filled, fragmentizing bomb. Words cognate with ''grenade'' are still used for an artillery or mortar projectile in some European languages. Shells are usually large-caliber projectiles fired by artillery, armored fighting vehicles (e.g. tanks, assault guns, and mortar carriers), warships, and autocannons. The shape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Homeland Security
The United States Department of Homeland Security (DHS) is the Federal government of the United States, U.S. United States federal executive departments, federal executive department responsible for public security, roughly comparable to the Interior minister, interior or home ministries of other countries. Its stated missions involve anti-terrorism, border security, immigration and customs, cyber security, and disaster prevention and management. It began operations in 2003, formed as a result of the Homeland Security Act of 2002, enacted in response to the September 11 attacks. With more than 240,000 employees, DHS is the third-largest Cabinet of the United States, Cabinet department, after the Departments of United States Department of Defense, Defense and United States Department of Veterans Affairs, Veterans Affairs. Homeland security policy is coordinated at the White House by the United States Homeland Security Council, Homeland Security Council. Other agencies with signi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Guard Of The United States
The National Guard is a state-based military force that becomes part of the reserve components of the United States Army and the United States Air Force when activated for federal missions.National Guard: FAQ . . Accessed February 2, 2022. It is a military reserve force composed of National Guard military members or units of each state and the territories of , the |
United States Armed Forces
The United States Armed Forces are the military forces of the United States. The armed forces consists of six service branches: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. The president of the United States is the commander-in-chief of the armed forces and forms military policy with the Department of Defense (DoD) and Department of Homeland Security (DHS), both federal executive departments, acting as the principal organs by which military policy is carried out. All six armed services are among the eight uniformed services of the United States. From their inception during the American Revolutionary War, the U.S. Armed Forces have played a decisive role in the history of the United States. They helped forge a sense of national unity and identity through victories in the First Barbary War and the Second Barbary War. They played a critical role in the American Civil War, keeping the Confederacy from seceding from the republic and preserving the uni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Fuel
Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing and sustaining nuclear fission. The three most relevant fissile isotopes are uranium-233, uranium-235 and plutonium-239. When the unstable nuclei of these atoms are hit by a slow-moving neutron, they frequently split, creating two daughter nuclei and two or three more neutrons. In that case, the neutrons released go on to split more nuclei. This creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon. Alternatively, if the nucleus absorbs the neutron without splitting, it creates a heavier nucleus with one additional neutron. The processes involved in mining, refining, purifying, using, and disposing of nuclear fuel are collectively known as the nuclear fuel cycle. Not all typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nuclear fission is passed to a working fluid (water or gas), which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, or for production of weapons-grade plutonium. , the International Atomic Energy Agency reports there are 422 nuclear power reactors and 223 nuclear research reactors in operation around the world. In the early era of nuclear reactors (1940s), a reactor was known as a nuclear pile or atomic pile (so-called because the graphite moderator blocks of the first reactor were placed into a tall pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrochemical
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as maize, palm fruit or sugar cane. The two most common petrochemical classes are olefins (including ethylene and propylene) and aromatics (including benzene, toluene and xylene isomers). Oil refineries produce olefins and aromatics by fluid catalytic cracking of petroleum fractions. Chemical plants produce olefins by steam cracking of natural gas liquids like ethane and propane. Aromatics are produced by catalytic reforming of naphtha. Olefins and aromatics are the building-blocks for a wide range of materials such as solvents, detergents, and adhesives. Olefins are the basis for polymers and oligomers used in plastics, resins, fibers, elastomers, lubricants, and gels. Global ethylene production was 190 million tonnes an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics In Medicine And Biology
''Physics in Medicine & Biology'' is a biweekly peer-reviewed medical journal covering research on the application of physics to medicine, physiology, and biology. It was established in 1956 and is published by IOP Publishing on behalf of the Institute of Physics and Engineering in Medicine. It is also an official journal of the following medical societies: Canadian Organization of Medical Physics, Deutsche Gesellschaft für Medizinische Physik, Japanese Association of Radiological Physics, European Federation of Organisations for Medical Physics, and the International Organization for Medical Physics. The editor-in-chief is Katia Parodi (Ludwig Maximilian University of Munich). Abstracting and indexing The journal is abstracted and indexed in: * Inspec *Chemical Abstracts *BIOSIS Previews/Biological Abstracts *Compendex * Embase/Excerpta Medica *PASCAL *Science Citation Index *Current Contents *Index Medicus/MEDLINE/PubMed *VINITI Database RAS According to the ''Journal Citatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
