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Oxygen-17
Oxygen-17 (17O) is a low-abundance, natural, stable isotope of oxygen (0.0373% in seawater; approximately twice as abundant as deuterium). As the only stable isotope of oxygen possessing a nuclear spin (+) and a favorable characteristic of field-independent relaxation in liquid water, 17O enables NMR studies of oxidative metabolic pathways through compounds containing 17O (i.e. metabolically produced H217O water by oxidative phosphorylation in mitochondria) at high magnetic fields. Water used as nuclear reactor coolant is subjected to intense neutron flux. Natural water starts out with 373 ppm of 17O; heavy water starts out incidentally enriched to about 550 ppm of oxygen-17. The neutron flux slowly converts 16O in the cooling water to 17O by neutron capture, increasing its concentration. The neutron flux slowly converts 17O (with much greater cross section) in the cooling water to carbon-14, an undesirable product that can escape to the environment: : 17O (n,α) → 14C S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heavy Water
Heavy water (deuterium oxide, , ) is a form of water (molecule), water in which hydrogen atoms are all deuterium ( or D, also known as ''heavy hydrogen'') rather than the common hydrogen-1 isotope (, also called ''protium'') that makes up most of the hydrogen in normal water. The presence of the heavier isotope gives the water different nuclear properties, and the increase in mass gives it slightly different physical and chemical properties when compared to normal water. Deuterium is a heavy Isotopes of hydrogen, hydrogen isotope. Heavy water contains deuterium atoms and is used in nuclear reactors. Semiheavy water (HDO) is more common than pure heavy water, while heavy-oxygen water is denser but lacks unique properties. Tritiated water is radioactive due to tritium content. Heavy water has different physical properties from regular water, such as being 10.6% denser and having a higher melting point. Heavy water is less Dissociation (chemistry), dissociated at a given temperatur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tritium
Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the common isotope hydrogen-1 (''protium'') contains one proton and no neutrons, and that of non-radioactive hydrogen-2 ('' deuterium'') contains one proton and one neutron. Tritium is the heaviest particle-bound isotope of hydrogen. It is one of the few nuclides with a distinct name. The use of the name hydrogen-3, though more systematic, is much less common. Naturally occurring tritium is extremely rare on Earth. The atmosphere has only trace amounts, formed by the interaction of its gases with cosmic rays. It can be produced artificially by irradiation of lithium or lithium-bearing ceramic pebbles in a nuclear reactor and is a low-abundance byproduct in normal operations of nuclear reactors. Tritium is used as the energy source in radio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relaxation (NMR)
In magnetic resonance imaging (MRI) and nuclear magnetic resonance spectroscopy (NMR), an observable nuclear spin polarization (magnetization) is created by a homogeneous magnetic field. This field makes the magnetic dipole moments of the sample precess at the resonance ( Larmor) frequency of the nuclei. At thermal equilibrium, nuclear spins precess randomly about the direction of the applied field. They become abruptly phase coherent when they are hit by radiofrequency (RF) pulses at the resonant frequency, created orthogonal to the field. The RF pulses cause the population of spin-states to be perturbed from their thermal equilibrium value. The generated transverse magnetization can then induce a signal in an RF coil that can be detected and amplified by an RF receiver. The return of the longitudinal component of the magnetization to its equilibrium value is termed ''spin-lattice'' relaxation while the loss of phase-coherence of the spins is termed ''spin-spin'' relaxation, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen-18
Oxygen-18 (, Ω) is a natural, stable isotope of oxygen and one of the environmental isotopes. is an important precursor for the production of fluorodeoxyglucose (FDG) used in positron emission tomography (PET). Generally, in the radiopharmaceutical industry, enriched water () is bombarded with hydrogen ions in either a cyclotron or linear accelerator, producing fluorine-18. This is then synthesized into FDG and injected into a patient. It can also be used to make an extremely heavy version of water when combined with tritium (hydrogen-3): or . This compound has a density almost 30% greater than that of natural water. The accurate measurements of rely on proper procedures of analysis, sample preparation and storage. Paleoclimatology In ice cores, mainly Arctic and Antarctic, the ratio of to (known as δ) can be used to determine the temperature of precipitation through time. Assuming that atmospheric circulation and elevation has not changed significantly over the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stable Nuclide
Stable nuclides are isotopes of a chemical element whose nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The nuclei of such isotopes are not radioactive and unlike radionuclides do not spontaneously undergo radioactive decay. When these nuclides are referred to in relation to specific elements they are usually called that element's stable isotopes. The 80 elements with one or more stable isotopes comprise a total of 251 nuclides that have not been shown to decay using current equipment. Of these 80 elements, 26 have only one stable isotope and are called monoisotopic. The other 56 have more than one stable isotope. Tin has ten stable isotopes, the largest number of any element. Definition of stability, and naturally occurring nuclides Most naturally occurring nuclides are stable (about 251; see list at the end of this article), and about 35 more (total of 286) are known to be radioactive with long eno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorine-17
Fluorine (9F) has 19 known isotopes ranging from to and two isomers ( and ). Only fluorine-19 is stable and naturally occurring in more than trace quantities; therefore, fluorine is a monoisotopic and mononuclidic element. The longest-lived radioisotope is ; it has a half-life of . All other fluorine isotopes have half-lives of less than a minute, and most of those less than a second. The least stable known isotope is , whose half-life is , corresponding to a resonance width of . List of isotopes , -id=Fluorine-13 , , style="text-align:right" , 9 , style="text-align:right" , 4 , # , , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 1/2+# , , -id=Fluorine-14 , , style="text-align:right" , 9 , style="text-align:right" , 5 , , [] , p ?Decay mode shown is energetically allowed, but has not been experimentally observed to occur in this nuclide. , ? , 2− , , -id=Fluorine-15 , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen-17
Natural nitrogen (7N) consists of two stable isotopes: the vast majority (99.6%) of naturally occurring nitrogen is nitrogen-14, with the remainder being nitrogen-15. Thirteen radioisotopes are also known, with atomic masses ranging from 9 to 23, along with three nuclear isomers. All of these radioisotopes are short-lived, the longest-lived being nitrogen-13 with a half-life of . All of the others have half-lives shorter than ten seconds, with most of these being below 500 milliseconds. Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of , though the half-life of nitrogen-9 has not been measured exactly. List of isotopes , -id=Nitrogen-9 , , style="text-align:right" , 7 , style="text-align:right" , 2 , , , , -id=Nitrogen-14m , style="text-indent:1em" , , colspan="3" style="text-indent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxygen-16
Oxygen-16 (symbol: 16O or ) is a nuclide. It is a stable isotope of oxygen, with 8 neutrons and 8 protons in its nucleus, and when not ionized, 8 electrons orbiting the nucleus. Oxygen-16 has a mass of . It is the most abundant isotope of oxygen and accounts for 99.757% of oxygen's natural abundance. The relative and absolute abundances of oxygen-16 are high because it is a principal product of stellar evolution and because it is a primordial isotope, meaning it can be made by stars that were initially made exclusively of hydrogen. Most oxygen-16 is synthesized at the end of the helium fusion process in stars; the triple-alpha process creates carbon-12, which captures an additional helium-4 to make oxygen-16. It is also created by the neon-burning process. Oxygen-16 is doubly magic. Solid samples (organic and inorganic) for oxygen-16 studies are usually stored in silver cups and measured with pyrolysis and mass spectrometry. Researchers need to avoid improper or prolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Giauque
William Francis Giauque (; May 12, 1895 – March 28, 1982) was a Canadian-born American chemist and Nobel laureate. He was recognized in 1949, for his studies in the properties of matter, at temperatures close to absolute zero. He spent virtually all of his educational and professional career at the University of California, Berkeley. Biography William Francis Giauque was born in Niagara Falls, Ontario, on May 12, 1895. His father (William Tecumseh Giauque) was an American citizen, and so William Francis Giauque was conferred American citizenship, despite being born in Canada, allowing him to attend public grammar schools in Michigan. In 1908, his father died, and he returned to Canada for his secondary education. After completing a two-year business course at the Niagara Falls Collegiate Institute, he searched for work in the field of electrical engineering, and eventually found employment at the Hooker Electrochemical Company in Niagara Falls, New York. He decided to become ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson (30 August 1871 – 19 October 1937) was a New Zealand physicist who was a pioneering researcher in both Atomic physics, atomic and nuclear physics. He has been described as "the father of nuclear physics", and "the greatest experimental physics, experimentalist since Michael Faraday". In 1908, he was awarded the Nobel Prize in Chemistry "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances." He was the first Oceanian Nobel laureate, and the first to perform the awarded work in Canada. Rutherford's discoveries include the concept of radioactive half-life, the radioactive element radon, and the differentiation and naming of Alpha decay, alpha and Beta particle, beta radiation. Together with Thomas Royds, Rutherford is credited with proving that alpha radiation is composed of helium nuclei. In 1911, he theorized that atoms have their charge concentrated in a very small atomi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frederick Soddy
Frederick Soddy FRS (2 September 1877 – 22 September 1956) was an English radiochemist who explained, with Ernest Rutherford, that radioactivity is due to the transmutation of elements, now known to involve nuclear reactions. He also proved the existence of isotopes of certain radioactive elements. In 1921, he received the Nobel Prize in Chemistry "for his contributions to our knowledge of the chemistry of radioactive substances, and his investigations into the origin and nature of isotopes". Soddy was a polymath who mastered chemistry, nuclear physics, statistical mechanics, finance, and economics. Biography Soddy was born at 6 Bolton Road, Eastbourne, England, the son of Benjamin Soddy, corn merchant, and his wife Hannah Green. He went to school at Eastbourne College, before going on to study at University College of Wales at Aberystwyth and at Merton College, Oxford, where he graduated in 1898 with first class honours in chemistry. He was a researcher at Oxford f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Transmutation
Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed. A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay, where no outside cause is needed. Natural transmutation by stellar nucleosynthesis in the past created most of the heavier chemical elements in the known existing universe, and continues to take place to this day, creating the vast majority of the most common elements in the universe, including helium, oxygen and carbon. Most stars carry out transmutation through fusion reactions involving hydrogen and helium, while much larger stars are also capable of fusing heavier elements up to iron late in their evolution. Elements heavier than iron, such as gold or lead, are created through elemental transmutations that can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
