query: What is the heaviest naturally occurring element?

title: Naturally occurring radioactive material

text: Naturally occurring radioactive material Naturally Occurring Radioactive Materials (NORM) and Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium and any of their decay products, such as radium and radon. Natural radioactive elements are present in very low concentrations in Earth's crust, and are brought to the surface through human activities such as oil and gas exploration or mining, and through natural processes like leakage of radon gas to the atmosphere or through dissolution in ground water. Another example of

text: 1 NORM industrial activity or a type 2 NORM industrial activity. Naturally occurring radioactive material Naturally Occurring Radioactive Materials (NORM) and Technologically Enhanced Naturally Occurring Radioactive Materials (TENORM) consist of materials, usually industrial wastes or by-products enriched with radioactive elements found in the environment, such as uranium, thorium and potassium and any of their decay products, such as radium and radon. Natural radioactive elements are present in very low concentrations in Earth's crust, and are brought to the surface through human activities such as oil and gas exploration or mining, and through natural processes like leakage of radon gas to

title: Synthetic element

text: short half-lives. The following elements do not occur naturally on Earth. All are transuranium elements and have atomic numbers of 95 and higher. All elements with atomic numbers 1 through 94 are naturally occurring at least in trace quantities, but the following elements are often produced through synthesis. Except for polonium, francium, actinium, and protactinium, they were all discovered through synthesis before being found in nature. Synthetic element In chemistry, a synthetic element is a chemical element that does not occur naturally on Earth, and can only be created artificially. So far, 24 synthetic elements have been created (those with

title: Period 5 element

text: and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature. Naturally occurring technetium occurs as a spontaneous fission product in uranium ore or by neutron capture in molybdenum ores. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese. Many of technetium's properties were predicted by Dmitri Mendeleev before the element was discovered. Mendeleev noted a gap in his periodic table and gave the undiscovered element the provisional name "ekamanganese"

title: Chemical element

text: remaining naturally occurring chemical elements were identified and characterized by 1900, including: Elements isolated or produced since 1900 include: The first transuranium element (element with atomic number greater than 92) discovered was neptunium in 1940. Since 1999 claims for the discovery of new elements have been considered by the IUPAC/IUPAP Joint Working Party. As of January 2016, all 118 elements have been confirmed as discovered by IUPAC. The discovery of element 112 was acknowledged in 2009, and the name "copernicium" and the atomic symbol "Cn" were suggested for it. The name and symbol were officially endorsed by IUPAC on 19

title: Chemical element

text: neutrons) for a particular isotope of an element, with this number combined with the pertinent element's symbol. IUPAC prefers that isotope symbols be written in superscript notation when practical, for example C and U. However, other notations, such as carbon-12 and uranium-235, or C-12 and U-235, are also used. As a special case, the three naturally occurring isotopes of the element hydrogen are often specified as H for H (protium), D for H (deuterium), and T for H (tritium). This convention is easier to use in chemical equations, replacing the need to write out the mass number for each atom.

title: Period 6 element

text: University of California, Berkeley in 1940. Three years later, it was found in nature; however, with an estimated amount of less than 28 grams (1 oz) at given time, astatine is the least abundant element in Earth's crust among non-transuranium elements. Among astatine isotopes, six (with mass numbers 214 to 219) are present in nature as the result of decay of heavier elements; however, the most stable astatine-210 and the industrially used astatine-211 are not. Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as the

title: Chemical element

text: through 94 are unstable to the point that radioactive decay of all isotopes can be detected. Some of these elements, notably bismuth (atomic number 83), thorium (atomic number 90), and uranium (atomic number 92), have one or more isotopes with half-lives long enough to survive as remnants of the explosive stellar nucleosynthesis that produced the heavy metals before the formation of our Solar System. At over 1.9 years, over a billion times longer than the current estimated age of the universe, bismuth-209 (atomic number 83) has the longest known alpha decay half-life of any naturally occurring element, and is almost

text: UK regulation is via the Environmental Permitting (England and Wales)Regulations 2010. This defines two types of NORM activity: (a)the production and use of thorium, or thorium compounds, and the production of products where thorium is deliberately added; or (b)the production and use of uranium or uranium compounds, and the production of products where uranium is deliberately added (a)the extraction, production and use of rare earth elements and rare earth element alloys; (b)the mining and processing of ores other than uranium ore; (c)the production of oil and gas; (d)the removal and management of radioactive scales and precipitates from equipment associated with

title: Chemical element

text: of crystal structures: cubic, body-centered cubic, face-centered cubic, hexagonal, monoclinic, orthorhombic, rhombohedral, and tetragonal. For some of the synthetically produced transuranic elements, available samples have been too small to determine crystal structures. Chemical elements may also be categorized by their origin on Earth, with the first 94 considered naturally occurring, while those with atomic numbers beyond 94 have only been produced artificially as the synthetic products of man-made nuclear reactions. Of the 94 naturally occurring elements, 83 are considered primordial and either stable or weakly radioactive. The remaining 11 naturally occurring elements possess half lives too short for them to

title: Uranium in the environment

text: in munitions is controversial because of questions about potential long-term health effects. Uranium is a naturally occurring element found in low levels within all rock, soil, and water. This is the highest-numbered element to be found naturally in significant quantities on earth. According to the United Nations Scientific Committee on the Effects of Atomic Radiation the normal concentration of uranium in soil is 300 μg/kg to 11.7 mg/kg. It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten and is about as abundant as tin, arsenic or molybdenum. It is found in many minerals

title: Transactinide element

text: Transactinide element In chemistry, transactinide elements (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers from 104 to 120. Their atomic numbers are immediately greater than those of the actinides, the heaviest of which is lawrencium (atomic number 103). Glenn T. Seaborg first proposed the actinide concept, which led to the acceptance of the actinide series. He also proposed the transactinide series ranging from element 104 to 121 and the superactinide series approximately spanning elements 122 to 153. The transactinide seaborgium was named in his honor. By definition, transactinide elements are also transuranic elements, i.e. have an

title: Transuranium element

text: by Glenn T. Seaborg, and are categorised as the "island of stability". Heavy transuranic elements are difficult and expensive to produce, and their prices increase rapidly with atomic number. As of 2008, the cost of weapons-grade plutonium was around $4,000/gram, and californium exceeded $60,000,000/gram. Einsteinium is the heaviest transuranic element that has ever been produced in macroscopic quantities. Transuranic elements that have not been discovered, or have been discovered but are not yet officially named, use IUPAC's systematic element names. The naming of transuranic elements may be a source of controversy. So far, essentially all the transuranium elements have been

title: Naturally occurring phenols

text: such as "Botrytis cinerea" and delta-viniferin is another grapevine phytoalexin produced following fungal infection by "Plasmopara viticola". Pinosylvin is a pre-infectious stilbenoid toxin (i.e. synthesized prior to infection), contrary to phytoalexins, which are synthesized during infection. It is present in the heartwood of Pinaceae. It is a fungitoxin protecting the wood from fungal infection. Sakuranetin is a flavanone, a type of flavonoid. It can be found in "Polymnia fruticosa" and rice, where it acts as a phytoalexin against spore germination of "Pyricularia oryzae". In "Sorghum", the "SbF3'H2" gene, encoding a flavonoid 3'-hydroxylase, seems to be expressed in pathogen-specific 3-deoxyanthocyanidin phytoalexins

title: Synthetic element

text: of the Earth. Only minute traces of technetium occur naturally in the Earth's crust—as a spontaneous fission product of uranium-238 or by neutron capture in molybdenum ores—but technetium is present naturally in red giant stars. The first discovered purely synthetic element was curium, synthesized in 1944 by Glenn T. Seaborg, Ralph A. James, and Albert Ghiorso by bombarding plutonium with alpha particles. The discoveries of americium, berkelium, and californium followed soon. Einsteinium and fermium were discovered by a team of scientists led by Albert Ghiorso in 1952 while studying the radioactive debris from the detonation of the first hydrogen bomb.

title: Chemical element

text: universe's 94 naturally occurring chemical elements are thought to have been produced by at least four cosmic processes. Most of the hydrogen, helium and a very small quantity of lithiumin the universe was produced primordially in the first few minutes of the Big Bang. Other three recurrently occurring later processes are thought to have produced the remaining elements. Stellar nucleosynthesis, an ongoing process inside stars, produces all elements from carbon through iron in atomic number, but little lithium, beryllium, or boron. Elements heavier in atomic number than iron, as heavy as uranium and plutonium, are produced by explosive nucleosynthesis in

title: Uranium

text: Uranium is a naturally occurring element that can be found in low levels within all rock, soil, and water. Uranium is the 51st element in order of abundance in the Earth's crust. Uranium is also the highest-numbered element to be found naturally in significant quantities on Earth and is almost always found combined with other elements. The decay of uranium, thorium, and potassium-40 in the Earth's mantle is thought to be the main source of heat that keeps the outer core liquid and drives mantle convection, which in turn drives plate tectonics. Uranium's average concentration in the Earth's crust is

title: Naturally occurring phenols

text: The white rot fungus "Phanerochaete chrysosporium" can remove up to 80% of phenolic compounds from coking waste water. Tannins are used in the tanning industry. Some natural phenols can be used as biopesticides. Furanoflavonoids like karanjin or rotenoids are used as acaricide or insecticide. Enological tannins are important elements in the flavor of wine. Some phenols are sold as dietary supplements. Phenols have been investigated as drugs. For instance, Crofelemer (USAN, trade name Fulyzaq) is a drug under development for the treatment of diarrhea associated with anti-HIV drugs. Additionally, derivatives have been made of phenolic compound, combretastatin A-4, an anticancer

title: Naturally occurring phenols

text: Naturally occurring phenols In biochemistry, naturally occurring phenols refers to phenol functional group that is found in natural products. Phenolic compounds are are produced by plants and microorganisms. Organisms sometimes synthesize phenolic compounds in response to ecological pressures such as pathogen and insect attack, UV radiation and wounding. As they are present in food consumed in human diets and in plants used in traditional medicine of several cultures, their role in human health and disease is a subject of research. Some phenols are germicidal and are used in formulating disinfectants. Various classification schemes can be applied. A commonly used scheme

title: Naturally occurring phenols

text: human gene encoding a phenol UDP glucuronosyltransferase active on simple phenols. The enzyme encoded by the gene UGT1A8 has glucuronidase activity with many substrates including coumarins, anthraquinones and flavones. Naturally occurring phenols In biochemistry, naturally occurring phenols refers to phenol functional group that is found in natural products. Phenolic compounds are are produced by plants and microorganisms. Organisms sometimes synthesize phenolic compounds in response to ecological pressures such as pathogen and insect attack, UV radiation and wounding. As they are present in food consumed in human diets and in plants used in traditional medicine of several cultures, their role in

title: Naturally occurring retirement community

text: South Houses, a ten-building 2,800-unit moderate-income housing cooperative located in New York City, with support from the UJA/Federation of New York. Since then, the NORC program model has been broadly replicated at the local, state, and national levels and can be found in more than 25 states across the country. Naturally occurring retirement community A naturally occurring retirement community (NORC; ) is a term used to describe a community that has a large proportion of residents over 60 but was not specifically planned or designed to meet the needs of seniors living independently in their homes. NORCs may develop in

text: Naturally occurring retirement community A naturally occurring retirement community (NORC; ) is a term used to describe a community that has a large proportion of residents over 60 but was not specifically planned or designed to meet the needs of seniors living independently in their homes. NORCs may develop in three different ways: The demographic term "NORC" was first coined in the 1980s by Michael Hunt, a professor of urban planning at the University of Wisconsin-Madison. He defined NORCs as neighborhoods and housing developments, originally built for young families, in which 50 percent of the residents are 60 years or

title: Period 6 element

text: oxide. Bismuth metal has been known from ancient times, although until the 18th century it was often confused with lead and tin, which each have some of the metal's bulk physical properties. The etymology is uncertain but possibly comes from Arabic "bi ismid" meaning having the properties of antimony or German words "weisse masse" or "wismuth" meaning"white mass." Bismuth is the most naturally diamagnetic of all metals, and only mercury has a lower thermal conductivity. Bismuth has classically been considered to be the heaviest naturally occurring stable element, in terms of atomic mass. Recently, however, it has been found to

title: DNA damage (naturally occurring)

text: or via environmental factors. The DNA damage response (DDR) is a complex signal transduction pathway which recognizes when DNA is damaged and initiates the cellular response to the damage. Damage to DNA that occurs naturally can result from metabolic or hydrolytic processes. Metabolism releases compounds that damage DNA including reactive oxygen species, reactive nitrogen species, reactive carbonyl species, lipid peroxidation products and alkylating agents, among others, while hydrolysis cleaves chemical bonds in DNA. Naturally occurring oxidative DNA damages arise at least 10,000 times per cell per day in humans and 50,000 times or more per cell per day in rats,

title: Chemical element

text: than the current estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any naturally occurring element. The very heaviest 24 elements (those beyond plutonium, element 94) undergo radioactive decay with short half-lives and cannot be produced as daughters of longer-lived elements, and thus they do not occur in nature at all. The properties of the chemical elements are often summarized using the periodic table, which powerfully and elegantly organizes the elements by increasing atomic number into rows ("periods") in which the columns ("groups") share recurring ("periodic") physical and chemical properties. The current standard table contains

title: Monoisotopic element

text: primordially which are not monoisotopic because the naturally occurring nuclide is radioactive, and thus the element has no stable isotopes at all. For an element to be monoisotopic, it must have one stable nuclide. Non-mononuclidic elements are marked with an asterisk, and the long-lived primordial radioisotope given. In two notable cases (indium and rhenium), the highest abundance naturally occurring isotope is the mildly radioactive one, and in the case of europium, nearly half of it is. Monoisotopic element A monoisotopic element is one of 26 chemical elements which have only a single stable isotope (nuclide). A list is given in

title: DNA damage (naturally occurring)

text: it is hypothesized that RAD9 forms a complex with RAD1 and HUS1, and this complex is recruited to sites of DNA damage. It is in this way that RAD9 is able to exert its effects. Although the function of RAD9 has primarily been studied in the budding yeast Saccharomyces cerevisiae, many of the cell cycle control mechanisms are similar between species. Thus, we can conclude that RAD9 likely plays a critical role in the DNA damage response in humans as well. DNA damage (naturally occurring) DNA damage is distinctly different from mutation, although both are types of error in DNA.

title: DNA damage (naturally occurring)

text: DNA damage (naturally occurring) DNA damage is distinctly different from mutation, although both are types of error in DNA. DNA damage is an abnormal chemical structure in DNA, while a mutation is a change in the sequence of standard base pairs. DNA damages cause changes in the structure of the genetic material and prevents the replication mechanism from functioning and performing properly. DNA damage and mutation have different biological consequences. While most DNA damages can undergo DNA repair, such repair is not 100% efficient. Un-repaired DNA damages accumulate in non-replicating cells, such as cells in the brains or muscles of

title: Period 7 element

text: As a rule, period 7 elements fill their 7s shells first, then their 5f, 6d, and 7p shells, in that order; however, there are exceptions, such as plutonium. All elements of period 7 are radioactive. This period contains the actinides, which contains the heaviest naturally occurring element, plutonium; subsequent elements must be synthesized artificially. Whilst the first five of these are now available in macroscopic quantities, most are extremely rare, having only been prepared in microgram amounts or less. The later, transactinide elements have only been identified in laboratories in batches of a few atoms at a time. Although the

title: DNA damage (naturally occurring)

text: (or tolerance) are shown in this table. For a brief description of the steps in repair see DNA repair mechanisms or see each individual pathway. The schematic diagram indicates the roles of insufficient DNA repair in aging and cancer, and the role of apoptosis in cancer prevention. An excess of naturally occurring DNA damage, due to inherited deficiencies in particular DNA repair enzymes, can cause premature aging or increased risk for cancer (see DNA repair-deficiency disorder). On the other hand, the ability to trigger apoptosis in the presence of excess un-repaired DNA damage is critical for prevention of cancer. DNA

title: DNA damage (naturally occurring)

text: as documented below. Oxidative DNA damage can produce more than 20 types of altered bases as well as single strand breaks. Other types of endogeneous DNA damages, given below with their frequencies of occurrence, include depurinations, depyrimidinations, double-strand breaks, O6-methylguanines and cytosine deamination. DNA can be damaged via environmental factors as well. Environmental agents such as UV light, ionizing radiation, and genotoxic chemicals. Replication forks can be stalled due to damaged DNA and double strand breaks are also a form of DNA damage. The list below, from reference, shows some frequencies with which new naturally occurring DNA damages arise per

title: Chemical element

text: formation of Earth, they are extremely likely, to the point of certainty, to have already decayed, and if present in novae have been in quantities too small to have been noted. Technetium was the first purportedly non-naturally occurring element synthesized, in 1937, although trace amounts of technetium have since been found in nature (and also the element may have been discovered naturally in 1925). This pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring rare elements. List of the elements are available by name, atomic number, density, melting point, boiling point and

title: Chemical element

text: these numbers are integers), and also resolves some ambiguities in the chemistry-based view due to varying properties of isotopes and allotropes within the same element. Currently, IUPAC defines an element to exist if it has isotopes with a lifetime longer than the 10 seconds it takes the nucleus to form an electronic cloud. By 1914, seventy-two elements were known, all naturally occurring. The remaining naturally occurring elements were discovered or isolated in subsequent decades, and various additional elements have also been produced synthetically, with much of that work pioneered by Glenn T. Seaborg. In 1955, element 101 was discovered and

title: What Comes Naturally

text: What Comes Naturally What Comes Naturally is the tenth studio album by Scottish-born singer Sheena Easton, released in 1991 through MCA Records. This album includes Easton’s final American Top 40 hit to date, "What Comes Naturally", which remained on the pop chart for 10 weeks. Other singles released were "You Can Swing It" and "To Anyone", both which failed to chart. The album charted in the United States at number 90. Easton is the co-writer on three tracks on the album. Easton is one of the few white artists to adopt the new jack swing sound from the early 1990s

title: What Comes Naturally

text: with chart success. What Comes Naturally What Comes Naturally is the tenth studio album by Scottish-born singer Sheena Easton, released in 1991 through MCA Records. This album includes Easton’s final American Top 40 hit to date, "What Comes Naturally", which remained on the pop chart for 10 weeks. Other singles released were "You Can Swing It" and "To Anyone", both which failed to chart. The album charted in the United States at number 90. Easton is the co-writer on three tracks on the album. Easton is one of the few white artists to adopt the new jack swing sound from

title: Chemical element

text: naturally produced in nucleogenic reactions, or in cosmogenic processes, such as cosmic ray spallation. New atoms are also naturally produced on Earth as radiogenic daughter isotopes of ongoing radioactive decay processes such as alpha decay, beta decay, spontaneous fission, cluster decay, and other rarer modes of decay. Of the 94 naturally occurring elements, those with atomic numbers 1 through 82 each have at least one stable isotope (except for technetium, element 43 and promethium, element 61, which have no stable isotopes). Isotopes considered stable are those for which no radioactive decay has yet been observed. Elements with atomic numbers 83

title: Group 7 element

text: high melting and boiling points. Group 7 contains the two naturally occurring transition metals discovered last: technetium and rhenium. Manganese was discovered much earlier owing to its much larger abundance in nature. Rhenium was discovered when Masataka Ogawa found what he thought was element 43 in thorianite, but this was dismissed; recent studies by H. K. Yoshihara suggest that he discovered rhenium instead, a fact not realized at the time. Walter Noddack, Otto Berg, and Ida Tacke were the first to conclusively identify rhenium; it was thought they discovered element 43 as well, but as the experiment could not be

title: P element

text: effect contributes to piRNAs being inherited only in the maternal line, which provides a defence mechanism against P elements. The P element has found wide use in "Drosophila" research as a mutagen. The mutagenesis system typically uses an autonomous but immobile element, and a mobile nonautonomous element. Flies from subsequent generations can then be screened by phenotype or PCR. Naturally-occurring P elements contain: Transposase is an enzyme that regulates and catalyzes the excision of a P element from the host DNA, cutting at two recognition sites, and then reinserting randomly. It is the random insertion that may interfere with existing

title: Period 2 element

text: a supplement for the prevention and treatment of osteoporosis and arthritis. Carbon is the chemical element with atomic number 6, occurring as C, C and C. At standard temperature and pressure, carbon is a solid, occurring in many different allotropes, the most common of which are graphite, diamond, the fullerenes and amorphous carbon. Graphite is a soft, hexagonal crystalline, opaque black semimetal with very good conductive and thermodynamically stable properties. Diamond however is a highly transparent colourless cubic crystal with poor conductive properties, is the hardest known naturally occurring mineral and has the highest refractive index of all gemstones. In

title: Period 5 element

text: Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and it has often been classified as a "rare earth element". Yttrium is almost always found combined with the lanthanides in rare earth minerals and is never found in nature as a free element. Its only stable isotope, Y, is also its only naturally occurring isotope. In 1787, Carl Axel Arrhenius found a new mineral near Ytterby in Sweden and named it "ytterbite", after the village. Johan Gadolin discovered yttrium's oxide in Arrhenius' sample in 1789, and

title: Period 2 element

text: alloys with aluminium, cadmium, copper and manganese are used to make high performance parts for aircraft, most notably the external tank of the Space Shuttle. Beryllium (Be) is the chemical element with atomic number 4, occurring in the form of Be. At standard temperature and pressure, beryllium is a strong, steel-grey, light-weight, brittle, bivalent alkali earth metal, with a density of 1.85 g·cm. It also has one of the highest melting points of all the light metals. Beryllium's most common isotope is Be, which contains 4 protons and 5 neutrons. It makes up almost 100% of all naturally occurring beryllium

title: Period 6 element

text: price of approximately US$4,575 per kilogram (US$142.30 per troy ounce) as of August 2011; it is also of critical strategic military importance, for its use in high performance military jet and rocket engines. Osmium is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, blue-gray or blue-black transition metal in the platinum family and is the densest naturally occurring element, with a density of (slightly greater than that of iridium and twice that of lead). It is found in nature as an alloy, mostly in platinum ores; its alloys with platinum, iridium, and

title: Group 5 element

text: Group 5 element Group 5 (by IUPAC style) is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals. The lighter three Group 5 elements occur naturally and share similar properties; all three are hard refractory metals under standard conditions. The fourth element, dubnium, has been synthesized in laboratories, but it has not been found occurring in nature, with half-life of

title: Chemical element

text: always considered on par with the 80 stable elements. The very heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives so short that they are not found in nature and must be synthesized. As of 2010, there are 118 known elements (in this context, "known" means observed well enough, even from just a few decay products, to have been differentiated from other elements). Of these 118 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and

title: DNA damage (naturally occurring)

text: to progress to mitosis. The three main checkpoints are at G1/s, G2/m, and at the spindle assembly checkpoint regulating progression through anaphase. G1 and G2 checkpoints involve scanning for damaged DNA. During S phase the cell is more vulnerable to DNA damage than any other part of the cell cycle. G2 checkpoint checks for damaged DNA and DNA replication completeness. DNA damage is an alteration in the chemical structure of DNA, such as a break in a strand of DNA, a base missing from the backbone of DNA, or a chemically changed base as 8-OHdG. DNA damage can occur naturally

title: Period 5 element

text: electrical contacts and the production of thick-film resistors. A minor application of ruthenium is its use in some platinum alloys. Rhodium is a chemical element that is a rare, silvery-white, hard, and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope,Rh. Naturally occurring rhodium is found as the free metal, alloyed with similar metals, and never as a chemical compound. It is one of the rarest precious metals and one of the most costly (gold has since taken over the top

title: Period 2 element

text: is the 33rd most abundant element on earth, occurring in concentrations of between 20 and 70 ppm by weight, but due to its high reactivity it is only found naturally in compounds. Lithium salts are used in the pharmacology industry as mood stabilising drugs. They are used in the treatment of bipolar disorder, where they have a role in treating depression and mania and may reduce the chances of suicide. The most common compounds used are lithium carbonate, LiCO, lithium citrate, LiCHO, lithium sulphate, LiSO, and lithium orotate, LiCHNO·HO. Lithium is also used in batteries as an anode and its

title: Chemical element

text: February 2010. The heaviest element that is believed to have been synthesized to date is element 118, oganesson, on 9 October 2006, by the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. Tennessine, element 117 was the latest element claimed to be discovered, in 2009. On 28 November 2016, scientists at the IUPAC officially recognized the names for four of the newest chemical elements, with atomic numbers 113, 115, 117, and 118. The following sortable table shows the 118 known chemical elements. Chemical element A chemical element is a species of atoms having the same number of protons in their

title: Heaviest trains

text: from Beyer-Peacock. These locos increased the maximum load over 1:50 grades from 200 tons (203 tonnes) to 270 tons (274 tonnes). The world heaviest train record is registered as follow: Australia, BHP: 2001, trial with 682 ore cars and eight distributed GE AC6000CW locomotives with a total weight of 99,734 t (98,159 tons) South Africa, Sishen Saldanha: 1989, 660 fully laden ore trucks, nine electric locomotives, seven Diesel engines and three other cars made the journey,(70,543 tons train took 12 minutes to pass by the watching engineers. Heaviest trains The heaviest trains in the world are freight trains hauling bulk

title: What Is the Fastest Thing in the World?

text: of which was good and some bad. The king set riddles to them: whoever guessed the riddles would get good land. The first riddle was what was the fastest thing in the world. The stupid brother's daughter told him what to say; his brother guessed a bird or a horse, and the stupid brother said the mind. The second riddle was what was the heaviest thing in the world; the clever brother guessed stone or iron, and the stupid brother repeated his daughter's answer: fire because no one could lift it. The third was what was the most important thing

title: Terbium

text: CeF. Naturally occurring terbium is composed of its only stable isotope, terbium-159; the element is thus called mononuclidic and monoisotopic. Thirty-six radioisotopes have been characterized, with the heaviest being terbium-171 (with atomic mass of 170.95330(86) u) and lightest being terbium-135 (exact mass unknown). The most stable synthetic radioisotopes of terbium are terbium-158, with a half-life of 180 years, and terbium-157, with a half-life of 71 years. All of the remaining radioactive isotopes have half-lives that are much less than a quarter of a year, and the majority of these have half-lives that are less than half a minute. The primary

title: Heaviest trains

text: Heaviest trains The heaviest trains in the world are freight trains hauling bulk commodities such as coal and iron ore. The weight of trains generally does not include the weight of the operating locomotives; this is not considered dead weight, so is not included. If for example a train had two locomotives operating and was simply hauling a third off line, this third locomotive would be included in the payload weight. If the track and its alignment are strong, gauge is not so important. Among railways with over gross train weight, the Sishen–Saldanha railway line uses , while the others

title: Periodic table

text: rather than in rows, and those columns numbered I to VIII corresponding with the element's oxidation state. He also gave detailed predictions for the properties of elements he had earlier noted were missing, but should exist. These gaps were subsequently filled as chemists discovered additional naturally occurring elements. It is often stated that the last naturally occurring element to be discovered was francium (referred to by Mendeleev as "eka-caesium") in 1939. Plutonium, produced synthetically in 1940, was identified in trace quantities as a naturally occurring element in 1971. The popular periodic table layout, also known as the common or standard

title: Synthetic element

text: Synthetic element In chemistry, a synthetic element is a chemical element that does not occur naturally on Earth, and can only be created artificially. So far, 24 synthetic elements have been created (those with atomic numbers 95–118). All are unstable, decaying with half-lives ranging from 15.6 million years to a few hundred microseconds. Seven other elements were first created artificially and thus considered synthetic, but later discovered to exist naturally (in trace quantities) as well; among them plutonium—first synthesized in 1940—the one best known to laypeople, because of its use in atomic bombs and nuclear reactors. Synthetic elements are radioactive

title: Group 12 element

text: four. Coordination numbers of 2, 3, 5, 7 and 8 are also known. Although copernicium is the heaviest known group 12 element, there has been some theoretical work regarding possible heavier group 12 elements. Although a simple extrapolation of the periodic table would put element 162, unhexbium (Uhb), under copernicium, relativistic Dirac-Fock calculations predict that the next group 12 element after copernicium should actually be element 164, unhexquadium (Uhq), which is predicted to have an electron configuration of [Og] 5g 6f 7d 8s 8p. The 8s and 8p orbitals are predicted to be so strongly stabilized relativistically that they become

title: Period (periodic table)

text: nonmetal. Of the three heaviest elements with biological roles, two (molybdenum and iodine) are in this period; tungsten, in period 6, is heavier, along with several of the early lanthanides. Period 5 also includes technetium, the lightest exclusively radioactive element. Period 6 is the first period to include the f-block, with the lanthanides (also known as the rare earth elements), and includes the heaviest stable elements. Many of these heavy metals are toxic and some are radioactive, but platinum and gold are largely inert. All elements of period 7 are radioactive. This period contains the heaviest element which occurs naturally

title: Period 7 element

text: Period 7 element A period 7 element is one of the chemical elements in the seventh row (or "period") of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The seventh period contains 32 elements, tied for the most with period 6, beginning with francium and ending with oganesson, the heaviest element currently discovered.

title: Heaviest Corner on Earth

text: Heaviest Corner on Earth The Heaviest Corner on Earth is a promotional name given to the corner of 20th Street and 1st Avenue North in Birmingham, Alabama, United States, in the early 20th century. The name reflected the nearly simultaneous appearance of four of the tallest buildings in the South, the 10-story "Woodward Building" (1902), 16-story "Brown Marx Building" (1906), 16-story "Empire Building" (1909), and the 21-story "American Trust and Savings Bank Building" (1912). The announcement of the last building was made in the "Jemison Magazine" in a January 1911 article titled "Birmingham to Have the Heaviest Corner in the

title: Heaviest Corner on Earth

text: 11, 1985. Heaviest Corner on Earth The Heaviest Corner on Earth is a promotional name given to the corner of 20th Street and 1st Avenue North in Birmingham, Alabama, United States, in the early 20th century. The name reflected the nearly simultaneous appearance of four of the tallest buildings in the South, the 10-story "Woodward Building" (1902), 16-story "Brown Marx Building" (1906), 16-story "Empire Building" (1909), and the 21-story "American Trust and Savings Bank Building" (1912). The announcement of the last building was made in the "Jemison Magazine" in a January 1911 article titled "Birmingham to Have the Heaviest Corner

title: Transactinide element

text: mix characteristics of the elements of group 10, 12, and 18. Transactinide element In chemistry, transactinide elements (also, transactinides, or super-heavy elements) are the chemical elements with atomic numbers from 104 to 120. Their atomic numbers are immediately greater than those of the actinides, the heaviest of which is lawrencium (atomic number 103). Glenn T. Seaborg first proposed the actinide concept, which led to the acceptance of the actinide series. He also proposed the transactinide series ranging from element 104 to 121 and the superactinide series approximately spanning elements 122 to 153. The transactinide seaborgium was named in his honor.

title: Period 5 element

text: dimethyl telluride, (CH)Te, a gas with a garlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure. Iodine is the heaviest essential element utilized widely by life in biological functions (only tungsten, employed in enzymes by a few species of bacteria, is heavier). Iodine's rarity in many soils, due to initial low abundance as a crust-element, and also leaching of soluble iodide by rainwater, has led to many deficiency problems in land animals and inland human populations. Iodine deficiency affects about two billion people and is the leading preventable cause of intellectual disabilities. Iodine is

title: Group 12 element

text: "water-silver" (hydr- = water, argyros = silver) — since it is liquid like water and shiny like silver. The element was named after the Roman god Mercury, known for speed and mobility. It is associated with the planet Mercury; the astrological symbol for the planet is also one of the alchemical symbols for the metal. Mercury is the only metal for which the alchemical planetary name became the common name. The heaviest known group 12 element, copernicium, was first created on February 9, 1996, at the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, by Sigurd Hofmann, Victor Ninov et al.

title: Period 6 element

text: away rapidly, so much less is known about this element than its upper neighbors in the periodic table. Earlier studies have shown this element follows periodic trends, being the heaviest known halogen, with melting and boiling points being higher than those of lighter halogens. Until recently most of the chemical characteristics of astatine were inferred from comparison with other elements; however, important studies have already been done. The main difference between astatine and iodine is that the HAt molecule is chemically a hydride rather than a halide; however, in a fashion similar to the lighter halogens, it is known to

title: Chemical element

text: to cause chemical effects), the isotopes of a given element are chemically nearly indistinguishable. All of the elements have some isotopes that are radioactive (radioisotopes), although not all of these radioisotopes occur naturally. The radioisotopes typically decay into other elements upon radiating an alpha or beta particle. If an element has isotopes that are not radioactive, these are termed "stable" isotopes. All of the known stable isotopes occur naturally (see primordial isotope). The many radioisotopes that are not found in nature have been characterized after being artificially made. Certain elements have no stable isotopes and are composed "only" of radioactive

title: Chemical element

text: Chemical element A chemical element is a species of atoms having the same number of protons in their atomic nuclei (that is, the same atomic number, or "Z"). For example, the atomic number of oxygen is 8, so the element oxygen consists of all atoms which have exactly 8 protons. 118 elements have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements. Iron is the most abundant

title: Mononuclidic element

text: Mononuclidic element A mononuclidic element or monotopic element is one of the 22 chemical elements that is found naturally on Earth essentially as a single nuclide (which may, or may not, be a stable nuclide). This single nuclide will have a characteristic atomic mass. Thus, the element's natural isotopic abundance is dominated either by one stable isotope or by one very long-lived isotope. There are 19 elements in the first category (which are both monoisotopic and mononuclidic), and 3 (bismuth, thorium and protactinium) in the second category (mononuclidic but not monoisotopic, since they have zero, not one, stable nuclides). A

title: Chemical element

text: whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the

title: What Is the What

title: What Is the What

title: Finite element method

text: with variable size "h", polynomial degree of the local approximations "p" and global differentiability of the local approximations "(k-1)" in order to achieve best convergence rates. The extended finite element method (XFEM) is a numerical technique based on the generalized finite element method (GFEM) and the partition of unity method (PUM). It extends the classical finite element method by enriching the solution space for solutions to differential equations with discontinuous functions. Extended finite element methods enrich the approximation space so that it is able to naturally reproduce the challenging feature associated with the problem of interest: the discontinuity, singularity, boundary

title: Period 2 element

text: in all living organisms, and the nitrogen cycle describes movement of the element from air into the biosphere and organic compounds, then back into the atmosphere. Synthetically produced nitrates are key ingredients of industrial fertilizers, and also key pollutants in causing the eutrophication of water systems. Nitrogen is a constituent element of amino acids and thus of proteins, and of nucleic acids (DNA and RNA). It resides in the chemical structure of almost all neurotransmitters, and is a defining component of alkaloids, biological molecules produced by many organisms. Oxygen is the chemical element with atomic number 8, occurring mostly as

title: Naturally 7

text: the competition. Riding their new-found success and still having made no decision whether to have Naturally 7 as an "a cappella" group or a traditional band, Roger had the novel idea that the group would become both. Naturally 7 has released a number of albums over the years since the formation at New York City in 1999, including their first debut studio album entitled "Non-Fiction" released in 2000, "What Is It" released in 2003, "Christmas... It's a Love Story" released in 2004, and "Ready II Fly" in 2006, released through Virginia Records. The group gained success by the partial cover

title: Initiator element

text: as the most frequently occurring sequence at the start site of genes in multiple species. Further research can allow for more understanding of the elements that regulate gene production. In nucleic acid notation for DNA, K stands for G/T (Keto) 2. Initiator element The initiator element ("Inr"), sometimes referred to as initiator motif, is a core promoter that is similar in function to the Pribnow box (in prokaryotes) or the TATA box (in eukaryotes). The "Inr" is the simplest functional promoter that is able to direct transcription initiation without a functional TATA box. It has the consensus sequence YYANWYY. Similarly

title: Naturally occurring phenols

text: oxidation of a phenolic substance forming sclerotin. In the analogous hardening of the cockroach ootheca, the phenolic substance concerned is 3:4-dihydroxybenzoic acid (protocatechuic acid). Acetosyringone is produced by the male leaffooted bug ("Leptoglossus phyllopus") and used in its communication system. Guaiacol is produced in the gut of Desert locusts, "Schistocerca gregaria", by the breakdown of plant material. This process is undertaken by the gut bacterium "Pantoea agglomerans". Guaiacol is one of the main components of the pheromones that cause locust swarming. Orcinol has been detected in the "toxic glue" of the ant species "Camponotus saundersi". "Rhynchophorus ferrugineus" (red palm weevil)

title: Naturally occurring phenols

text: is converted back to its colorless neutral form. The reaction may be monitored spectrophotometrically. This assay is often referred to as the Trolox equivalent antioxidant capacity (TEAC) assay. The reactivity of the various antioxidants tested are compared to that of Trolox, which is a vitamin E analog. Other antioxidant capacity assays that use Trolox as a standard include the diphenylpicrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), ferric reducing ability of plasma (FRAP) assays or inhibition of copper-catalyzed "in vitro" human low-density lipoprotein oxidation. A cellular antioxidant activity (CAA) assay also exists. Dichlorofluorescin is a probe that is trapped within cells

title: Earth (classical element)

text: (the platonic solids) and he assigned the cube to the element of "earth" in his dialogue "Timaeus". Aristotle (384–322 BCE) believed "earth" was the heaviest element, and his theory of "natural place" suggested that any "earth–laden" substances, would fall quickly, straight down, towards the center of the "cosmos". In Classical Greek and Roman myth, various goddesses represented the Earth, seasons, crops and fertility, including Demeter and Persephone; Ceres; the Horae (goddesses of the seasons), and Proserpina; and Hades (Pluto) who ruled the souls of dead in the Underworld. In ancient Greek medicine, each of the four humours became associated with

title: Group 3 element

text: the current heaviest element known, oganesson. In 1787, Swedish part-time chemist Carl Axel Arrhenius found a heavy black rock near the Swedish village of Ytterby, Sweden (part of the Stockholm Archipelago). Thinking that it was an unknown mineral containing the newly discovered element tungsten, he named it ytterbite. Finnish scientist Johan Gadolin identified a new oxide or "earth" in Arrhenius' sample in 1789, and published his completed analysis in 1794; in 1797, the new oxide was named "yttria". In the decades after French scientist Antoine Lavoisier developed the first modern definition of chemical elements, it was believed that earths could

title: Naturally occurring phenols

text: phenols is then expressed as equivalents of the appropriate standard. Some methods for quantification of total phenolic content are based on colorimetric measurements. Total phenols (or antioxidant effect) can be measured using the Folin-Ciocalteu reaction. Results are typically expressed as "gallic acid equivalents" (GAE). Ferric chloride (FeCl) test is also a colorimetric assay. Lamaison and Carnet have designed a test for the determination of the total flavonoid content of a sample (AlCI method). After proper mixing of the sample and the reagent, the mixture is incubated for 10 minutes at ambient temperature and the absorbance of the solution is read

title: Naturally occurring phenols

text: molecule, including nitrogen or halogens atoms to increase the efficacy of the treatment. Phenol extraction is a processing technology used to prepare phenols as raw materials, compounds or additives for industrial wood processing and for chemical industries. Extraction can be performed using different solvents. There is a risk that polyphenol oxidase (PPO) degrades the phenolic content of the sample therefore there is a need to use PPO inhibitors like potassium dithionite (KSO) or to perform experiment using liquid nitrogen or to boil the sample for a few seconds (blanching) to inactivate the enzyme. Further fractionation of the extract can be

title: Naturally occurring phenols

text: and recalcitrant humic substances by polymerization and condensation reactions (with the contribution of soil organisms); they might adsorb to clay minerals or form chelates with aluminium or iron ions; or they might remain in dissolved form, leached by percolating water, and finally leave the ecosystem as part of dissolved organic carbon (DOC). Leaching is the process by which cations such as iron (Fe) and aluminum (Al), as well as organic matter are removed from the litterfall and transported downward into the soil below. This process is known as podzolization and is particularly intense in boreal and cool temperate forests that

title: Naturally occurring phenols

text: achieved using solid phase extraction columns, and may lead to isolation of individual compounds. The recovery of natural phenols from biomass residue is part of biorefining. pK of phenolic compounds can be calculated from the retention time in liquid chromatography. Studies on evaluating antioxidant capacity can used electrochemical methods. Detection can be made by recombinant luminescent bacterial sensors. Phenolic profiling can be achieved with liquid chromatography–mass spectrometry (LC/MS). A method for phenolic content quantification is volumetric titration. An oxidizing agent, permanganate, is used to oxidize known concentrations of a standard solution, producing a standard curve. The content of the unknown

title: Naturally occurring phenols

text: synthesis, for example in "Sorghum-Colletotrichum" interactions. 6-Methoxymellein is a dihydroisocoumarin and a phytoalexin induced in carrot slices by UV-C, that allows resistance to "Botrytis cinerea" and other microorganisms. Danielone is a phytoalexin found in the papaya fruit. This compound showed high antifungal activity against "Colletotrichum gloesporioides", a pathogenic fungus of papaya. Stilbenes are produced in "Eucalyptus sideroxylon" in case of pathogens attacks. Such compounds can be implied in the hypersensitive response of plants. High levels of phenolics in some woods can explain their natural preservation against rot. In plants, VirA is a protein histidine kinase which senses certain sugars and

title: Naturally occurring phenols

text: claim that organically grown potatoes, oranges, and leaf vegetables have more phenolic compounds and these may provide antioxidant protection against heart disease and cancer. However evidence on substantial differences between organic food and conventional food is insufficient to make claims that organic food is safer or more healthy than conventional food. In animals and humans, after ingestion, natural phenols become part of the xenobiotic metabolism. In subsequent phase II reactions, these activated metabolites are conjugated with charged species such as glutathione, sulfate, glycine or glucuronic acid. These reactions are catalysed by a large group of broad-specificity transferases. UGT1A6 is a

title: Naturally occurring phenols

text: "Sargassum" and "Turbinaria" species that are often preferentially consumed by herbivorous fishes and echinoids, there is a relatively low level of phenolics and tannins. Marine allelochemicals generally are present in greater quantity and diversity in tropical than in temperate regions. Marine algal phenolics have been reported as an apparent exception to this biogeographic trend. High phenolic concentrations occur in brown algae species (orders Dictyotales and Fucales) from both temperate and tropical regions, indicating that latitude alone is not a reasonable predictor of plant phenolic concentrations. In "Vitis vinifera" grape, "trans"-resveratrol is a phytoalexin produced against the growth of fungal pathogens

title: Naturally occurring phenols

text: at 440 nm. Flavonoid content is expressed in mg/g of quercetin. Quantitation results produced by the means of diode array detector-coupled HPLC are generally given as relative rather than absolute values as there is a lack of commercially available standards for every phenolic molecules. The technique can also be coupled with mass spectrometry (for example, HPLC–DAD–ESI/MS) for more precise molecule identification. Other tests measure the antioxidant capacity of a fraction. Some make use of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation, which is reactive towards most antioxidants including phenolics, thiols and vitamin C. During this reaction, the blue ABTS radical cation

title: Element Hunters

text: Element Hunters In the year 2029, chemical elements such as oxygen, carbon, gold, molybdenum, and cobalt were continually disappearing from Earth. These disappearing elements ultimately disrupted the environment and led to the destruction of various homes, cities, and even entire countries. Researchers discovered that the vanishing elements drained into a planet called Nega Earth, located in another dimension. Element dematerialization was occurring rapidly; thus, to save Earth, three special pre-teens picked by the space colony government formed the Element Hunters. Their job was to transport themselves to Nega-Earth to battle monsters called Q-EXes and retrieve lost elements. However, out of

title: Naturally occurring phenols

text: the visible spectrum is absorbed. The wavelengths left in the process (generally in red section of the spectrum) recompose the color of the particular substance. Acylation with cinnamic acids of anthocyanidins shifted color tonality (CIE Lab hue angle) to purple. Here is a series of UV visible spectra of molecules classified from left to right according to their conjugation level: The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young "Quercus coccifera" leaves. Natural phenols are reactive species toward oxidation, notably the complex mixture of

title: Naturally occurring phenols

text: long aliphatic chains bonded to a phenolic moiety. Many natural phenols are chiral. An example of such molecules is catechin. Cavicularin is an unusual macrocycle because it was the first compound isolated from nature displaying optical activity due to the presence of planar chirality and axial chirality. Natural phenols show optical properties characteristic of benzene, e.g. absorption near 270 nm. According to Woodward's rules, bathochromic shifts often also happen suggesting the presence of delocalised π electrons arising from a conjugation between the benzene and vinyls groups. As molecules with higher conjugation levels undergo this bathochromic shift phenomenon, a part of

title: Naturally occurring phenols

text: been best known for its involvement in plant-pathogen recognition, especially its role as a signal attracting and transforming unique, oncogenic bacteria in genus "Agrobacterium". The virA gene on the Ti plasmid in the genome of "Agrobacterium tumefaciens" and "Agrobacterium rhizogenes" is used by these soil bacteria to infect plants, via its encoding for a receptor for acetosyringone and other phenolic phytochemicals exuded by plant wounds. This compound also allows higher transformation efficiency in plants, in A. tumefaciens mediated transformation procedures, and so is of importance in plant biotechnology. Notable sources of natural phenols in human nutrition include berries, tea, beer,

title: Naturally occurring phenols

text: phenolic compounds. These compounds are typically found from wounded plants, and as a result VirA is used by "Agrobacterium tumefaciens" to locate potential host organisms for infection. Natural phenols can be involved in allelopathic interactions, for example in soil or in water. Juglone is an example of such a molecule inhibiting the growth of other plant species around walnut trees. The aquatic vascular plant "Myriophyllum spicatum" produces ellagic, gallic and pyrogallic acids and (+)-catechin, allelopathic phenolic compounds inhibiting the growth of blue-green alga "Microcystis aeruginosa". Phenolics, and in particular flavonoids and isoflavonoids, may be involved in endomycorrhizae formation. Acetosyringone has

title: Naturally occurring phenols

text: is a phenolic compound found in the orchids "Gastrodia elata" and "Galeola faberi". Phenolics can also be found in non-vascular land plants (bryophytes). Dihydrostilbenoids and bis(bibenzyls) can be found in liverworts (Marchantiophyta), for instance, the macrocycles cavicularin and riccardin C. Though lignin is absent in mosses (Bryophyta) and hornworts (Anthocerotophyta), some phenolics can be found in those two taxa. For instance, rosmarinic acid and a rosmarinic acid 3'-O-β-D-glucoside can be found in the hornwort "Anthoceros agrestis". The hardening of the protein component of insect cuticle has been shown to be due to the tanning action of an agent produced by

title: Astatine

text: Astatine Astatine is a radioactive chemical element with symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. A sample of the pure element has never been assembled, because any macroscopic specimen would be immediately vaporized by the heat of its own radioactivity. The bulk properties of astatine are not known with any certainty. Many of them have been estimated based on the element's position on

title: Naturally occurring phenols

text: is based on the number of carbons and was devised by Jeffrey Harborne and Simmonds in 1964 and published in 1980: Not in this Harborne classification are the C-C-C diarylheptanoids. They can also be classified on the basis of their number of phenol groups. They can therefore be called "simple phenols" or "monophenols", with only one phenolic group, or "di-" ("bi-"), "tri-" and "oligophenols", with two, three or several phenolic groups respectively. A diverse family natural phenols are the flavonoids, which include several thousand compounds, among them the flavonols, flavones, flavan-3ol ("catechins"), flavanones, anthocyanidins, and isoflavonoids. The phenolic unit can

title: Naturally occurring phenols

text: be found dimerized or further polymerized, creating a new class of polyphenol. For example, ellagic acid is a dimer of gallic acid and forms the class of ellagitannins, or a catechin and a gallocatechin can combine to form the red compound theaflavin, a process that also results in the large class of brown thearubigins in tea. Two natural phenols from two different categories, for instance a flavonoid and a lignan, can combine to form a hybrid class like the flavonolignans. Nomenclature of polymers: Plants in the genus "Humulus" and "Cannabis" produce terpenophenolic metabolites, compounds that are meroterpenes. Phenolic lipids are

title: Naturally occurring phenols

text: are mainly constituted by coniferous pines whose litterfall is rich in phenolic compounds and fulvic acid. Phenolic compounds can act as protective agents, inhibitors, natural animal toxicants and pesticides against invading organisms, i.e. herbivores, nematodes, phytophagous insects, and fungal and bacterial pathogens. The scent and pigmentation conferred by other phenolics can attract symbiotic microbes, pollinators and animals that disperse fruits. Volatile phenolic compounds are found in plant resin where they may attract benefactors such as parasitoids or predators of the herbivores that attack the plant. In the kelp species "Alaria marginata", phenolics act as chemical defence against herbivores. In tropical

title: Naturally occurring phenols

text: sacs of the mature North American beaver ("Castor canadensis") and the European beaver ("Castor fiber"), used in perfumery. In some cases of natural phenols, they are present in vegetative foliage to discourage herbivory, such as in the case of Western poison oak. In soils, it is assumed that larger amounts of phenols are released from decomposing plant litter rather than from throughfall in any natural plant community. Decomposition of dead plant material causes complex organic compounds to be slowly oxidized lignin-like humus or to break down into simpler forms (sugars and amino sugars, aliphatic and phenolic organic acids), which are

title: Naturally occurring phenols

text: further transformed into microbial biomass (microbial humus) or are reorganized, and further oxidized, into humic assemblages (fulvic and humic acids), which bind to clay minerals and metal hydroxides. There has been a long debate about the ability of plants to uptake humic substances from their root systems and to metabolize them. There is now a consensus about how humus plays a hormonal role rather than simply a nutritional role in plant physiology. In the soil, soluble phenols face four different fates. They might be degraded and mineralized as a carbon source by heterotrophic microorganisms; they can be transformed into insoluble

title: Naturally occurring phenols

text: (i) the shikimate/chorizmate or succinylbenzoate pathway, which produces the phenyl propanoid derivatives (C6–C3); (ii) the acetate/malonate or polyketide pathway, which produces the side-chain-elongated phenyl propanoids, including the large group of flavonoids (C6–C3–C6) and some quinones; and (iii) the acetate/mevalonate pathway, which produces the aromatic terpenoids, mostly monoterpenes, by dehydrogenation reactions. The aromatic amino acid phenylalanine, synthesized in the shikimic acid pathway, is the common precursor of phenol containing amino acids and phenolic compounds. In plants, the phenolic units are esterified or methylated and are submitted to conjugation, which means that the natural phenols are mostly found in the glycoside form

title: Naturally occurring phenols

text: and is easily oxidized to fluorescent dichlorofluorescein (DCF). The method measures the ability of compounds to prevent the formation of DCF by 2,2'-Azobis(2-amidinopropane) dihydrochloride (ABAP)-generated peroxyl radicals in human hepatocarcinoma HepG2 cells. Other methods include butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), Rancimat method (rancidification assessment of fat). Larvae of the model animal "Galleria mellonella", also called waxworms, can be used to test the antioxidant effect of individual molecules using boric acid in food to induce induced an oxidative stress. The content of malondialdehyde, an oxidative stress indicator, and activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione S-transferase and glutathione

title: Naturally occurring phenols

text: "Botryococcus braunii" is the subject of research into the natural production of butylated hydroxytoluene (BHT), an antioxidant, food additive and industrial chemical. Phenolic acids such as protocatechuic, p-hydroxybenzoic, 2,3-dihydroxybenzoic, chlorogenic, vanillic, caffeic, "p"-coumaric and salicylic acid, cinnamic acid and hydroxybenzaldehydes such as p-hydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, vanillin have been isolated from in vitro culture of the freshwater green alga "Spongiochloris spongiosa". Phlorotannins, for instance eckol, are found in brown algae. Vidalenolone can be found in the tropical red alga "Vidalia sp". Phenolic compounds are mostly found in vascular plants (tracheophytes) i.e. Lycopodiophyta (lycopods), Pteridophyta (ferns and horsetails), Angiosperms (flowering plants or Magnoliophyta)