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A radionuclide is an atom with an unstable nucleus, characterized by excess energy available to be imparted either to a newly created radiation particle within the nucleus or via internal conversion. During this process, the radionuclide is said to undergo radioactive decay, resulting in the emission of gamma ray(s) and/or subatomic particles such as alpha or beta particles.^[1] These emissions constitute ionizing radiation. Radionuclides occur naturally, or can be produced artificially.

Radionuclides are often referred to by chemists and physicists as radioactive isotopes or radioisotopes. Radioisotopes with suitable half-lives play an important part in a number of technologies (for example, nuclear medicine). Radionuclides can also present both real and perceived dangers to health.

The number of radionuclides is uncertain because the number of very short-lived radionuclides that have yet to be characterized is extremely large and potentially unquantifiable. Even the number of long-lived radionuclides is uncertain (to a lesser degree), because many "stable" nuclides are calculated to have half-lives so long that their decay has not been experimentally measured. The total list of nuclides contains 90 nuclides that are theoretically stable, and 255 total stable nuclides that have not been observed to decay. In addition, there exist about 650 radionuclides that have been experimentally observed to decay, with half-lives longer than 60 minutes (see list of nuclides for this list). Of these, about 339 are known from nature (they have been observed on Earth, and not as a consequence of man-made activities).

Including artificially produced nuclides, more than 3300 nuclides are known (including ~3000 radionuclides), many of which (> ~2400) have decay half-lives shorter than 60 minutes. This list expands as new radionuclides with very short half-lives are characterized.

All elements form a number of radionuclides, although the half lives of many are too short for them to be observed in nature. Even the lightest element, hydrogen, has a well-known radioisotope, tritium. The heaviest elements (heavier than bismuth) exist only as radionuclides. For every chemical element, many radioisotopes that do not occur in nature (due to short half lives or the lack of an ongoing natural production mechanism), have been produced artificially.

Origin[link]

Naturally occurring radionuclides fall into three categories: primordial radionuclides, secondary radionuclides, and cosmogenic radionuclides. Primordial radionuclides, such as uranium and thorium, originate mainly from the interiors of stars and are still present as their half-lives are so long they have not yet completely decayed. Secondary radionuclides are radiogenic isotopes derived from the decay of primordial radionuclides. They have shorter half-lives than primordial radionuclides. Cosmogenic isotopes, such as carbon-14, are present because they are continually being formed in the atmosphere due to cosmic rays.^[2]

Artificially produced radionuclides can be produced by nuclear reactors, particle accelerators or by radionuclide generators:

• Radioisotopes produced with nuclear reactors exploit the high flux of neutrons present. These neutrons activate elements placed within the reactor. A typical product from a nuclear reactor is thallium-201 and iridium-192. The elements that have a large propensity to take up the neutrons in the reactor are said to have a high neutron cross-section.
• Particle accelerators such as cyclotrons accelerate particles to bombard a target to produce radionuclides. Cyclotrons accelerate protons at a target to produce positron emitting radioisotopes, e.g., fluorine-18.
• Radionuclide generators contain a parent isotope that decays to produce a radioisotope. The parent is usually produced in a nuclear reactor. A typical example is the technetium-99m generator used in nuclear medicine. The parent produced in the reactor is molybdenum-99.
• Radionuclides are produced as an unavoidable side effect of nuclear and thermonuclear explosions.

Trace radionuclides are those that occur in tiny amounts in nature either due to inherent rarity, or to half-lives that are significantly shorter than the age of the Earth. Synthetic isotopes are inherently not naturally occurring on Earth, but can be created by nuclear reactions.

Uses[link]

Radionuclides are used in two major ways: for their chemical properties and as sources of radiation. Radionuclides of familiar elements such as carbon can serve as tracers because they are chemically very similar to the non-radioactive nuclides, so most chemical, biological, and ecological processes treat them in a near identical way. One can then examine the result with a radiation detector, such as a geiger counter, to determine where the provided atoms ended up. For example, one might culture plants in an environment in which the carbon dioxide contained radioactive carbon; then the parts of the plant that had laid down atmospheric carbon would be radioactive.

In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma rays or positrons can provide diagnostic information about a person's internal anatomy and the functioning of specific organs. This is used in some forms of tomography: single-photon emission computed tomography and positron emission tomography scanning and Cerenkov luminescence imaging.

Radioisotopes are also a method of treatment in hemopoietic forms of tumors; the success for treatment of solid tumors has been limited. More powerful gamma sources sterilise syringes and other medical equipment.

In biochemistry and genetics, radionuclides label molecules and allow tracing chemical and physiological processes occurring in living organisms, such as DNA replication or amino acid transport.

In food preservation, radiation is used to stop the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables.

In industry, and in mining, radionuclides examine welds, to detect leaks, to study the rate of wear, erosion and corrosion of metals, and for on-stream analysis of a wide range of minerals and fuels.

Radionuclides are also used to trace and analyze pollutants, to study the movement of surface water, and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers. Natural radionuclides are used in geology, archaeology, and paleontology to measure ages of rocks, minerals, and fossil materials.

Common examples[link]

Americium-241[link]

Americium-241 container in a smoke detector.

Americium-241 capsule as found in smoke detector. The circle of darker metal in the center is americium-241, the surrounding casing is aluminium.

Most household smoke detectors contain americium formed in nuclear reactors. The radioisotope used is americium-241. The element americium is created by bombarding plutonium with neutrons in a nuclear reactor. Its isotope, Am-241 decays by emitting alpha particles and gamma radiation to become neptunium-237. The most common household smoke detectors use a very small quantity of Am-241 (about 0.29 micrograms per smoke detector) in the form of americium dioxide. The smoke detectors use the Am-241 since the alpha particles it emits collide with oxygen and nitrogen particles in the air. This occurs in the detector's ionization chamber where it produces charged particles or ions. Then, these charged particles are collected by a small electric voltage that will create an electric current that will pass between two electrodes. Then, the ions that are flowing between the electrodes will be neutralized when coming in contact with smoke, thereby decreasing the electric current between the electrodes, which will activate the detector's alarm. ^[3][4]

Steps for creating americium-241[link]

The plutonium-241 is formed in any nuclear reactor by neutron capture from uranium-238.

1. 238
   U + neutron => 239
   U
2. 239
   U by beta decay => 239
   Np
3. 239
   Np by beta decay => 239
   Pu
4. 239
   Pu + neutron => 240
   Pu
5. 240
   Pu + neutron => 241
   Pu

This will decay both in the reactor and subsequently to form Am-241 (Half-life: 432.2 years)^[5][6]

Gadolinium-153[link]

The Gd-153 isotope is used in X-ray fluorescence and osteoporosis screening. It is a gamma-emitter with an 8-month half-life, making it easier to use for medical purposes. In nuclear medicine, it serves to calibrate the equipment needed like single-photon emission computed tomography systems (SPECT) to make x-rays. It ensures that the machines work correctly to produce images of radioisotope distribution inside the patient. This isotope is produced in a nuclear reactor from europium or enriched gadolinium.^[7] It can also detect the loss of calcium in the hip and back bones, allowing the ability to diagnose osteoporosis. ^[8]

Dangers[link]

Radionuclides that find their way into the environment may cause harmful effects of radioactive contamination. They can also cause damage if they are excessively used during treatment or in other ways applied to living beings, by radiation poisoning.

Summary table for classes of nuclides, "stable" and radioactive[link]

Following is a summary table for the total list of nuclides with half-lives greater than one hour. Ninety of these 905 nuclides are theoretically stable, except to proton-decay (which has never been observed). About 255 nuclides have never been observed to decay, and are classically considered stable.

The remaining 650 radionuclides have half-lives longer than 1 hour, and are well characterized (see list of nuclides for a complete tabulation). They include 27 nuclides with measured half-lives longer than the estimated age of the universe (13.7 billion years), and another 6 nuclides with half-lives long enough (> 80 million years) that they are radioactive primordial nuclides, and may be detected on Earth, having survived from their presence in interstellar dust since before the formation of the solar system, about 4.6 billion years ago. Another ~51 short-lived nuclides can be detected naturally as daughters of longer-lived nuclides or cosmic-ray products. The remaining known nuclides are known solely from artificial nuclear transmutation.

Numbers are not exact, and may change slightly in the future, as "stable nuclides" are observed to be radioactive with very long half-lives.

This is a summary table ^[9] for the 905 nuclides with half-lives longer than one hour (including those that are stable), given in list of nuclides.

List of commercially available radionuclides[link]

This list covers common isotopes, most of which are available in very small quantities to the general public in the US and other countries. Others which are not publicly accessible are traded commercially in industrial, medical, and scientific fields and are subject to government regulation. For a complete list of all known isotopes for every element (minus activity data), see Isotope Lists and Table of Nuclides.

Gamma only[link]

Beta only[link]

Alpha only[link]

Multiple radiation emitters[link]

See also[link]

• List of nuclides shows all radionuclides with half-life > 1 hour
• Hyperaccumulators table – 3
• Radioactivity in biology
• Radiometric dating
• Radionuclide cisternogram

Notes[link]

References[link]

• Carlsson, J.; et al., E; Hietala, SO; Stigbrand, T; Tennvall, J (2003). "Tumour therapy with radionuclides: assessment of progress and problems". Radiotherapy and Oncology 66 (2): 107–117. DOI:10.1016/S0167-8140(02)00374-2. PMID 12648782. 
• "Radioisotopes in Industry". World Nuclear Association. http://world-nuclear.org/info/inf56.html. 
• Martin, James (2006). Physics for Radiation Protection: A Handbook. pp. 130. ISBN 3527406115. 

External links[link]

• EPA – Radionuclides – EPA's Radiation Protection Program: Information.
• FDA – Radionuclides – FDA's Radiation Protection Program: Information.
• Interactive Chart of Nuclides – A chart of all nuclides
• National Isotope Development Center – U.S. Government source of radionuclides – production, research, development, distribution, and information
• The Live Chart of Nuclides – IAEA
• Willey Online Library: Book Article

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Medicine 8 are a British electronic music duo composed of brothers Liam May and Luke May.

Biography[link]

The duo began Djing and producing in the mid-nineties under a variety of aliases, releasing music under their own imprint. Luke explained how they took on the Medicine 8 name in an interview with Scruff: “We started our own label in 1996 putting out twelve inches which was when everything really started, though that wasn’t as Medicine 8. It just so happened that one of the 12”s people picked up on was Capital Rocka, for which we had just happened to use the name Medicine 8, so we stuck with it,”.^[1]

They released their rock-fused electro debut album, IronStylings in 2002 on Regal Recordings to critical acclaim. The album spawned the singles Rock Music Pays Off and Capital Rocka. The latter of which had gained popularity in its own right after they gave a dub-plate to Carl Cox who played it at the Miami Music Winter Conference.

They have been regulars in Ibiza as well as at the Miami Winter Music Conference, and have appeared at many of the major UK dance festivals such as Glastonbury Festival, Creamfields and Homelands. They also held a residency at Pacha in Argentina and featured in a number of sessions on BBC Radio 1.^[2]

As remixers, they have re-worked tracks for Gus Gus, Kylie Minogue, Orbital, Manic Street Preachers, Nirvana, Tiga, X-Press2 and many others.

Now releasing music through their own label, Trashmouth Records,^[3] they began work on their second album in 2011. The year also took in live appearances that included the Cloud 9 Festival in Cheshire. ^[4]

Releases[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Medicine 8

• Medicine 8 on Facebook
• Medicine 8 on Twitter
• Video on YouTube
• Medicine 8 discography at Discogs

Kurt Everett Miller (August 24, 1972) is a former professional baseball pitcher. He played parts of five seasons in Major League Baseball, between 1994 and 1999, for the Chicago Cubs and Florida Marlins. He also played in two seasons Nippon Professional Baseball in Japan, 1999 and 2000, for the Hanshin Tigers.

Playing career[link]

Early career[link]

Miller was drafted by the Pittsburgh Pirates out of West High School in Bakersfield, California with the 5th overall pick in the 1990 MLB Draft. A little over a year later, he was traded to the Texas Rangers with fellow pitching prospect Héctor Fajardo for third baseman Steve Buechele. He spent nearly two seasons in the Rangers organization before being traded again, this time to the expansion Marlins, again with another pitching prospect, this time Robb Nen, for pitcher Cris Carpenter.

Marlins[link]

Miller finished the 1993 season with the Edmonton Trappers, the Marlins' Triple-A farm team. He began the 1994 season with Edmonton as well, but was called up to the major leagues in June to replace the injured Mark Gardner in the starting rotation. He made his major league debut at age 20 on June 11 against the team that had drafted him, the Pirates. He gave up 7 runs on 9 hits in just 4 innings pitched. He improved substantially in his next start, throwing 8.2 innings against the New York Mets and giving up just 4 hits. However, after two more bad starts he was returned to the minor leagues.

Miller's minor league numbers in 1994 were not impressive, either. He won 7 games and lost 13 while posting an ERA of 6.88. The next season, with the Marlins' new top farm club the Charlotte Knights, Miller's numbers improved to 8–11 with a 4.62 ERA.

Miller began the 1996 season back in Charlotte, but he was called up in early May. After pitching one game in relief, the first time he had appeared in the majors as a reliever and just his fifth professional relief appearance, he was moved back into the rotation to replace Chris Hammond. His first start was a good one, giving up just one run in eight innings against the Colorado Rockies, but after two less-successful starts he was sent back to the bullpen. He was subsequently returned to Charlotte in mid-July, where he returned to starting. He came back to the majors a month later, made two more starts, then spent September in the bullpen. In 26 major league games, Miller posted a record of 1–3 with an ERA of 6.80.

Miller spent most of 1997 in Charlotte, missing a chunk of the season due to an elbow injury.^[1] He returned to the Marlins to pitch 7 games in September, but gave up 8 runs in 7.1 innings. After the season, he was traded to the Cubs.

Remaining career[link]

Miller was assigned to the Triple-A Iowa Cubs to start the 1998 season, and he responded with his best season at that level, going 14–3 with a 3.81 ERA. He was brought up to the majors in late September, and pitched four scoreless innings over three games. He made the 1999 Cubs out of spring training, but pitched in just four games before suffering a ribcage injury. He came back to pitch in eight games in Iowa, and in June, he was allowed to go to Japan and sign with Hanshin.

Miller returned to starting with the Tigers, appearing in 11 games and posting a 2–4 record with a 5.98 ERA. The next season, the Tigers tried to use him as their closer, and he posted 6 saves in his first 17 games, but he also gave up 15 runs on 17 hits and 11 walks with a 7.41 ERA. He was released after the season.

Notes[link]

External links[link]

• Career statistics and player information from Baseball-Reference
• Foreign Pitching Stats K-M at Japan Baseball Daily

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