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Boiling

Boiling or ebullition is the rapid phase transition from liquid to gas or vapor; the reverse of boiling is condensation. Boiling occurs when a liquid is heated to its boiling point, so that the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere. Boiling and evaporation are the two main forms of liquid vapourization.

There are two main types of boiling: nucleate boiling where small bubbles of vapour form at discrete points, and critical heat flux boiling where the boiling surface is heated above a certain critical temperature and a film of vapour forms on the surface. Transition boiling is an intermediate, unstable form of boiling with elements of both types. The boiling point of water is 100 °C or 212 °F but is lower with the decreased atmospheric pressure found at higher altitudes.

Boiling water is used as a method of making it potable by killing microbes and viruses that may be present. The sensitivity of different micro-organisms to heat varies, but if water is held at 100 C for one minute, most micro-organisms and viruses are inactivated. Ten minutes at a temperature of 70 °C (158 °F) is also sufficient to inactivate most bacteria.

Boiling water is also used in several cooking methods including boiling, steaming, and poaching.

Free convection
The lowest heat flux seen in boiling is only sufficient to cause [natural convection], where the warmer fluid rises due to its slightly lower density. This condition occurs only when the superheat is very low, meaning that the hot surface near the fluid is nearly the same temperature as the boiling point.

Nucleate
Nucleate boiling is characterised by the growth of bubbles or pops on a heated surface (heterogeneous nucleation), which rises from discrete points on a surface, whose temperature is only slightly above the temperature of the liquid. In general, the number of nucleation sites is increased by an increasing surface temperature.

An irregular surface of the boiling vessel (i.e., increased surface roughness) or additives to the fluid (i.e., surfactants and/or nanoparticles) facilitate nucleate boiling over a broader temperature range, while an exceptionally smooth surface, such as plastic, lends itself to superheating. Under these conditions, a heated liquid may show boiling delay and the temperature may go somewhat above the boiling point without boiling.

Homogeneous nucleation, where the bubbles form from the surrounding liquid instead of on a surface, can occur if the liquid is warmer in its center, and cooler at the surfaces of the container. This can be done, for instance, in a microwave oven, which heats the water and not the container.

Critical heat flux
Critical heat flux (CHF) describes the thermal limit of a phenomenon where a phase change occurs during heating (such as bubbles forming on a metal surface used to heat water), which suddenly decreases the efficiency of heat transfer, thus causing localised overheating of the heating surface. As the boiling surface is heated above a critical temperature, a film of vapour forms on the surface. Since this vapour film is much less capable of carrying heat away from the surface, the temperature rises very rapidly beyond this point into the transition boiling regime. The point at which this occurs is dependent on the characteristics of boiling fluid and the heating surface in question.

Transition
Transition boiling may be defined as the unstable boiling, which occurs at surface temperatures between the maximum attainable in nucleate and the minimum attainable in film boiling.

The formation of bubbles in a heated liquid is a complex physical process which often involves cavitation and acoustic effects, such as the broad-spectrum hiss one hears in a kettle not yet heated to the point where bubbles boil to the surface.

Film
If a surface heating the liquid is significantly hotter than the liquid then film boiling will occur, where a thin layer of vapour, which has low thermal conductivity, insulates the surface. This condition of a vapour film insulating the surface from the liquid characterises film boiling.

Pool boiling
"Pool boiling" refers to boiling where there is no forced convective flow. Instead, the flow occurs due to density gradients. It can experience any of the regimes mentioned above.

Flow boiling
"Flow boiling" occurs when the boiling fluid circulates, typically through pipes. Its movement can be powered by pumps, such as in power plants, or by density gradients, such as in a Thermosiphon or a heat pipe. Flows in flow boiling are often characterised by a void fraction parameter, which indicates the fraction of the volume in the system that is vapor. One can use this fraction and the densities to calculate the vapor quality, which refers to the mass fraction that is in the gas phase. Flow boiling can be very complex, with heavy influences of density, flow rates, and heat flux, as well as surface tension. The same system may have regions that are liquid, gas, and two-phase flow. Such two phase regimes can lead to some of the best heat transfer coefficients of any system.

Confined boiling
Confined boiling refers to boiling in confined geometries, typically characterized by a Bond number that compares the gap spacing to the capillary length. Confined boiling regimes begin to play a major role when Bo < 0.5. This boiling regime is dominated by "vapour stem bubbles" left behind after vapour departs. These bubbles act as seeds for vapor growth. Confined boiling typically has higher heat transfer coefficient but a lower CHF than pool boiling. CHF occurs when the vapor momentum force at the two-phase interface balances the combined surface tension and hydrostatic forces, leading to irreversible growth of the dry spot. Confined boiling is particularly promising for electronics cooling.

Physics
The boiling point of an element at a given pressure is a characteristic attribute of the element. This is also true for many simple compounds including water and simple alcohols. Once boiling has started and provided that boiling remains stable and the pressure is constant, the temperature of the boiling liquid remains constant. This attribute led to the adoption of boiling points as the definition of 100 °C.

Distillation
Mixtures of volatile liquids have a boiling point specific to that mixture producing vapour with a constant mix of components - the constant boiling mixture. This attribute allows mixtures of liquids to be separated or partly separated by boiling and is best known as a means of separating ethanol from water.

Refrigeration and air conditioning
Most types of refrigeration and some type of air-conditioning work by compressing a gas so that it becomes liquid and then allowing it to boil. This adsorbs heat from the surroundings cooling the fridge or freezer or cooling the air entering a building. Typical liquids include propane, ammonia, carbon dioxide or nitrogen.

For making water potable
As a method of disinfecting water, bringing it to its boiling point at 100 °C, is the oldest and most effective way since it does not affect the taste, it is effective despite contaminants or particles present in it, and is a single step process which eliminates most microbes responsible for causing intestine related diseases. The boiling point of water is 100 C at sea level and at normal barometric pressure. In places having a proper water purification system, it is recommended only as an emergency treatment method or for obtaining potable water in the wilderness or in rural areas, as it cannot remove chemical toxins or impurities.

The elimination of micro-organisms by boiling follows first-order kinetics—at high temperatures, it is achieved in less time and at lower temperatures, in more time. The heat sensitivity of micro-organisms varies, at 70 °C, Giardia species (which cause giardiasis) can take ten minutes for complete inactivation, most intestine affecting microbes and E. coli (gastroenteritis) take less than a minute; at boiling point, Vibrio cholerae (cholera) takes ten seconds and hepatitis A virus (causes the symptom of jaundice), one minute. Boiling does not ensure the elimination of all micro-organisms; the bacterial spores Clostridium can survive at 100 °C but are not water-borne or intestine affecting. Thus for human health, complete sterilization of water is not required.

The traditional advice of boiling water for ten minutes is mainly for additional safety, since microbes start getting eliminated at temperatures greater than 60 °C and bringing it to its boiling point is also a useful indication that can be seen without the help of a thermometer, and by this time, the water is disinfected. Though the boiling point decreases with increasing altitude, it is not enough to affect the disinfecting process.

In cooking
Boiling is the method of cooking food in boiling water or other water-based liquids such as stock or milk. Simmering is gentle boiling, while in poaching the cooking liquid moves but scarcely bubbles.

The boiling point of water is typically considered to be 100 °C, especially at sea level. Pressure and a change in the composition of the liquid may alter the boiling point of the liquid. High elevation cooking generally takes longer since boiling point is a function of atmospheric pressure. At an elevation of about 1 mile, water boils at approximately 95 °C. Depending on the type of food and the elevation, the boiling water may not be hot enough to cook the food properly. Similarly, increasing the pressure as in a pressure cooker raises the temperature of the contents above the open air boiling point.

Boil-in-the-bag
Also known as "boil-in-bag", this involves heating or cooking ready-made foods sealed in a thick plastic bag. The bag containing the food, often frozen, is submerged in boiling water for a prescribed time. The resulting dishes can be prepared with greater convenience as no pots or pans are dirtied in the process. Such meals are available for camping as well as home dining.

Contrast with evaporation
At any given temperature, the molecules in a liquid have varying kinetic energies. Some high energy particles on the liquid surface may have enough energy to escape the intermolecular forces of attraction of the liquid and become a gas. This is called evaporation.

Evaporation only happens on the surface while boiling happens throughout the liquid. When a liquid reaches its boiling point bubbles of gas form in it which rise into the surface and burst into the air. This process is called boiling. If the boiling liquid is heated more strongly the temperature does not rise but the liquid boils more quickly.

This distinction is exclusive to the liquid-to-gas transition; any transition directly from solid to gas is always referred to as sublimation regardless of whether it is at its boiling point or not.

title: Boiling


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Altria

Altria Group, Inc. (previously known as Philip Morris Companies, Inc.) is an American corporation and one of the world's largest producers and marketers of tobacco, cigarettes, and medical products in the treatment of illnesses caused by tobacco. It operates worldwide and is headquartered in Henrico County, Virginia, just outside the city of Richmond.

Altria is the parent company of Philip Morris USA, John Middleton, Inc., U.S. Smokeless Tobacco Company, Inc., and Philip Morris Capital Corporation. Altria also maintains large minority stakes in Belgium-based brewer AB InBev and the Canadian cannabis company Cronos Group. It is a component of the S&P 500 and was a component of the Dow Jones Industrial Average from 1985 to 2008, dropping due to spin-offs of Kraft Foods Inc. in 2007 and Philip Morris International in 2008.

History
Altria emerged from Philip Morris USA. The onset of "rebranding" of Philip Morris Companies to Altria took place in 2003 (Philip Morris would later split, with PM USA remaining Altria's primary and only consistently held asset). According to Altria, it was created because Philip Morris wished to emphasize that its business portfolio had come to consist of more than Philip Morris USA and Philip Morris International; at the time, it owned an 84% stake in Kraft, although that business has since been spun off. The name "Altria" is claimed to come from the Latin word for "high" and was part of a trend of companies rebranding to names that previously did not exist, Accenture (previously Andersen Consulting) and Verizon being notable examples, though linguist Steven Pinker suggests that in fact the name is an "egregious example" of phonesthesia—with the company attempting to "switch its image from bad people who sell addictive carcinogens to a place or state marked by altruism and other lofty values".

The company's branding consultants, the Wirthlin Group, said: "The name change alternative offers the possibility of masking the negatives associated with the tobacco business", thus enabling the company to improve its image and raise its profile without sacrificing tobacco profits. Philip Morris executives thought a name change would insulate the larger corporation and its other operating companies from the political pressures on tobacco.

The rebranding took place amidst social, legal, and financially troubled circumstances. In 2003 Altria was ranked Fortune number 11, and has steadily declined since. In 2010 Altria Group (MO) ranked at Fortune number 137, whereas its former asset, Philip Morris International, was ranked 94th.

In 2006, a United States court found that Philip Morris "publicly ... disputed scientific findings linking smoking and disease knowing their assertions were false." In a 2006 ruling, a federal court found that Altria, along with R. J. Reynolds Tobacco, Lorillard and Philip Morris were found guilty of misleading the public about the dangers of smoking. Within this ruling, it was noted that "defendants altered the chemical form of nicotine delivered in mainstream cigarette smoke for the purpose of improving nicotine transfer efficiency and increasing the speed with which nicotine is absorbed by smokers." This was done by manipulating smoke pH with ammonia. Adding ammonia increases the smoke pH, in a process called "freebasing" which causes smokers to be "exposed to higher internal nicotine doses and become more addicted to the product."

On March 30, 2007, Altria's 88.1% stake in Kraft Foods was spun off, through a distribution of the remaining stake of shares (88.1%) to Altria shareholders. That same year, Altria began selling all its shares of Philip Morris International to Altria stockholders, a spin-off that was completed on March 28, 2008. Again in 2007 the company began the acquisition of cigar manufacturer John Middleton Co. from Bradford Holdings, which was complete in 2008. After Philip Morris International spun off, the former international subsidiaries halted the purchase of tobacco from America, which was a major factor in the closing of a newly renovated plant in North Carolina, an approximately 50% reduction in manufacturing, large-scale layoffs, and induced early retirements.

In 2008, Altria officially moved its headquarters from New York City to Richmond, Virginia, after Philip Morris sold its downtown offices in New York City a decade earlier. With a few exceptions, all manufacturing, commercial, and executive employees had long been based in and around Richmond. Currently the company is headquartered in an unincorporated area within Henrico County, less than five miles west of the city limits of Richmond and less than ten miles from its downtown Richmond campus.

Aside from the Philip Morris/Altria headquarters, some of their other buildings included the Altria Center for Research and Technology in downtown Richmond, their manufacturing center in South Richmond, and the adjacent operations center which began shutting down in 2007–2008, as a result of the loss of demand from PMI member companies. The layoffs beginning in 2007 affected thousands of Altria, Altria Client Services, Philip Morris USA, and contracted employees in Richmond and North Carolina.

In 2009, Altria finalized its purchase of UST Inc., whose products included smokeless tobacco (made by U.S. Smokeless Tobacco Company) and wine (made by Chateau Ste. Michelle). This ended a short era of competition between the new Marlboro smokeless tobacco products such as snus, and those produced by UST Inc.

On December 8, 2018, Altria announced its intent to acquire a 45% stake in Cronos Group for $1.8 billion.

On December 20, 2018, Altria finalized the acquisition of a 35% stake in JUUL Labs, an e-cigarette company based out of San Francisco, California, for $12.8 billion. On November 3, 2019, it was reported that Altria was taking a $4.5 billion writedown on its stake in Juul, 35% of its original value. On July 28, 2022, it was reported that Altria's investment in Juul is now worth only 5% of the original amount of $12.8 billion. Despite the losses, Altria has announced that it will continue to support Juul and avoid investing in competing products.

Altria is taking a stake in the global business of Swiss tobacco company Burger Söhne (Helix Innovations with the On! brand) for $372 million in June 2019.

Altria and Japan Tobacco announced a joint venture called Horizon Innovations LLC on October 27, 2022. Horizon, owned 75 percent by Altria and 25 percent by Japan Tobacco, intends to sell Ploom heated tobacco sticks in the United States. FDA approval was expected to take until 2025, with customers able to buy Ploom by 2027.

Altria completed the acquisition of NJOY Holdings, Inc. on June 1, 2023.

Finances
For the fiscal year 2020, Altria reported earnings of US$4.45 billion, with an annual revenue of US$26.15 billion. Altria's shares traded at over $66 per share, and its market capitalization was valued at over US$118.5 billion in October 2018. As of 2018, the company ranked 154th on the Fortune 500 list of the largest United States corporations by revenue.

Board of directors
Members of the board of directors of Altria Group as of February 2013 were:
 * Elizabeth E. Bailey, professor emerita, the Wharton School, University of Pennsylvania
 * Gerald L. Baliles (2008–2019), director, Miller Center of Public Affairs at University of Virginia; former Virginia governor
 * Martin Barrington, chairman and chief executive officer, Altria Group, Inc.
 * John T. Casteen III (2010– ), president emeritus, University of Virginia
 * Dinyar S. Devitre (2008– ), special advisor, General Atlantic Partners, New York, NY; former SVP and CFO of Altria
 * Thomas F. Farrell II (2008–2021), chairman, president and CEO, Dominion Resources, Richmond, VA
 * Thomas W. Jones (2002– ), senior partner, TWJ Capital LLC, Stamford, CT; formerly with Citigroup, Travelers and TIAA-CREF
 * Debra J. Kelly-Ennis (2013– ), former president and CEO of Diageo Canada, Inc.; also formerly with RJR Nabisco, Inc., Coca-Cola, General Motors and Grand Metropolitan
 * W. Leo Kiely III (2011– ), retired CEO, MillerCoors LLC, Golden, CO; formerly with Frito-Lay
 * Kathryn B. McQuade (2012– ), retired EVP and CFO, Canadian Pacific Railway Limited; formerly with Norfolk Southern Corporation
 * George Muñoz (2004– ), principal, Muñoz Investment Banking Group, LLC, Washington, DC; Partner, Tobin & Muñoz, Chicago, IL; formerly Overseas Private Investment Corporation and assistant secretary of the United States Treasury Department
 * Nabil Y. Sakkab (2008– ), retired Senior Vice President, corporate research and development, Procter & Gamble, Cincinnati, OH

Headquarters
Prior to being based in Virginia, Philip Morris had its headquarters in Midtown Manhattan, New York City. In 2003, Philip Morris announced that it would move its headquarters to Virginia. The company said that it planned to keep around 750 employees in its former headquarters. Brendan McCormick, a spokesperson for Philip Morris, said that the company estimated that the move would save the company over $60 million each year. The company now has its head offices in an unincorporated area of Henrico County, Virginia, near Richmond. In addition, the company has a 450,000-square-foot, $350 million Center for Research and Technology located in downtown Richmond at the Virginia BioTechnology Research Park that employs approximately 600 scientists, engineers and support staff.

Diversification
Altria like other tobacco companies, has invested in science and medical companies, which develop and produce medical products for conditions caused or aggravated by smoking. As of 2024, Altrias three medical subsidiaries included the following: Cronos group (maker of recreational cannabis), Lexaria Bioscience (Developer of proprietary drug delivery technology, DehydraTECH, to improve active pharmaceutical ingredients entrance into the bloodstream) and Micreos (biotech company focused on discovering and developing recombinant proteins for chronic dermatology and oncology conditions).

Political influence
According to the Center for Public Integrity, Altria spent around $101 million on lobbying the United States government between 1998 and 2004, the second-highest such figure for any organization in the nation.

Altria also funded The Advancement of Sound Science Coalition which lobbied against the scientific consensus on anthropogenic climate change.

Daniel Smith, representing Altria, sits on the Private Enterprise Board of the American Legislative Exchange Council.

Controversies
In August 2006, the Altria group was found guilty of civil fraud and racketeering. The lawsuit claimed that Altria's marketing of "light" and "low tar" cigarettes constituted fraudulent misrepresentations under the Maine Unfair Trade Practices Act (MUTPA) because it deceived smokers into thinking the products are safer than regular cigarettes.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Altria


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William McMahon

Sir William McMahon (23 February 1908 – 31 March 1988) was an Australian politician who served as the 20th prime minister of Australia from 1971 to 1972. He held office as the leader of the Liberal Party of Australia. He was a government minister for over 21 years, the longest continuous service in Australian history.

McMahon was born and raised in Sydney, and worked as a commercial lawyer before entering politics. He served in the Australian Army during World War II, reaching the rank of major. After the war's end he returned to university to complete an economics degree. McMahon was elected to the House of Representatives at the 1949 federal election. Robert Menzies promoted him to the ministry in 1951 and added him to cabinet in 1956. He held several different portfolios in the Menzies government, most notably as Minister for Labour and National Service from 1958 to 1966. In that capacity, he oversaw the reintroduction of conscription in 1964.

In 1966, Menzies retired and was replaced as prime minister by Harold Holt. McMahon then succeeded Holt as deputy leader of the Liberal Party. He was appointed Treasurer in the Holt government, and over the following three years oversaw a large reduction in the national deficit. After Holt's death in 1967, McMahon wished to contest the Liberal leadership but had his candidacy vetoed by John McEwen, the leader of the Country Party. The new prime minister was John Gorton. McMahon initially continued on as Treasurer in the Gorton government, but in 1969 was demoted to Minister for External Affairs after an unsuccessful challenge for the leadership. He eventually replaced Gorton in March 1971 following Gorton’s resignation, winning a vote against Billy Snedden.

McMahon became prime minister at the age of 63, and remains the oldest non-interim prime minister to take office. His government has been described by the Australian Dictionary of Biography as "a blend of cautious innovation and fundamental orthodoxy". It continued many of the policies of its immediate predecessors, such as the phased withdrawal of Australian troops from Vietnam. In its final year it faced high inflation and unemployment. Gough Whitlam's Labor Party defeated McMahon at the 1972 federal election, ending 23 consecutive years of Coalition rule. No other Australian prime minister has served for longer without winning a general election. He resigned the Liberal leadership, but remained in parliament until 1982 as a backbencher.

McMahon has been described as one of Australia's worst prime ministers by Australian political scientists and historians,  and after leaving office several of his former colleagues openly criticised his leadership style and personal character. Whitlam, his successor, acknowledged him as "an extraordinarily skilful, resourceful and tenacious politician", and credited him with having prevented a larger margin of defeat in 1972.

Birth and family background
McMahon was born in Redfern, Sydney, New South Wales, on 23 February 1908. He was the third of five children born to solicitor William Daniel McMahon and Mary (née Walder), daughter of a sailmaker; an older brother predeceased him. His father, a Catholic, had a reputation as a heavy drinker and habitual gambler; his mother, an Anglican, was of English and Irish descent.

McMahon's paternal grandfather, James "Butty" McMahon, was born in County Clare, Munster, Ireland, and married Mary Coyle of County Fermanagh, Ulster, Ireland. He arrived in Australia as a child, and eventually founded his own freight company, which became one of the largest in Sydney. Upon his death in 1914, his estate was valued at almost £240,000, an immense sum at the time.

Childhood and education
McMahon spent his early life in Redfern. His mother died in 1917, when he was nine years old, and he was subsequently raised by her relatives. He moved home frequently as he was shifted between family members, living for periods in Kensington, Beecroft, Gordon, and Centennial Park. McMahon saw little of his father or his siblings, who were raised separately; his older brother James died of Spanish flu in 1919. His uncle Samuel Walder – a businessman who was Lord Mayor of Sydney in 1932 – acted as a sort of surrogate father.

McMahon began his education at Abbotsholme College, a short-lived private school in Killara. One of his schoolmates there was Harold Holt, another future prime minister. He was later sent to Sydney Grammar School, where he was an above-average student without excelling academically.

McMahon's father died when he was 18, leaving him a substantial inheritance. He had failed the leaving certificate at Sydney Grammar. However, by his passing a matriculation exam, McMahon was able to enter the University of Sydney in 1927. At the insistence of his uncle, he chose to study law, graduating with a Bachelor of Laws in 1930. McMahon, who lived at St Paul's College, was more interested in the social scene than his degree. He spent his inheritance freely, owning several racehorses, and was known for betting significant amounts on the races. According to Alan Reid, "his reputation was that he completed his university career on less actual work than anyone in the college".

Despite his diminutive physique – he stood 5 ft as an adult – McMahon did achieve some success as an athlete. He won his university's lightweight boxing title, and in his final year at Sydney Grammar rowed in the Head of the River race.

Legal career and military service
According to Don Whitington, McMahon's life before entering politics was "the aimless, indolent existence of a wealthy young man with a position in a big city's smart set, no positive ambition or even interests, except in enjoying himself, and no family ties to give him a feeling of responsibility or even consideration for others". After graduating from university, he secured a position as a solicitor with Allen, Allen & Hemsley, a major Sydney law firm; he was made a junior partner in 1939. He was assigned to the Commonwealth Bank and the Bank of New South Wales for periods, which helped spark his interest in economics. McMahon had hoped to practise as a barrister, but his partial deafness made this impractical. His hearing remained an issue throughout his life, making parliamentary debates hard to follow, but did improve somewhat through surgery and the use of hearing aids.

In April 1940, McMahon was commissioned as a lieutenant in the Citizens Military Force. He transferred to the Australian Imperial Force (the regular army) in October 1940, and was promoted to captain in 1942 and to major in 1943. McMahon was turned down for overseas service due to his hearing loss and a knee injury. In the early part of the war he was attached to coastal defence units in Sydney. He later served on the headquarters staff of the II Corps (1942–1943) and the Second Army (1943–1945). He was formally discharged in October 1945.

After leaving the military, McMahon travelled overseas for 18 months, visiting Europe and North America. His experience of post-war Europe was said to have been one of the primary influences on his subsequent decision to enter politics. In 1947, McMahon returned to the University of Sydney to study economics and public administration. He graduated with a Bachelor of Economics degree in 1948, completing the course two years early due to his previous studies. He topped his economics class and won two prizes for proficiency in his final year.

Under Menzies
McMahon was elected to the House of Representatives at the 1949 federal election, winning the newly created Division of Lowe for the Liberal Party. His candidacy was endorsed by Billy Hughes, who had known his grandfather. McMahon soon developed a reputation as "a deadly earnest, dogged, enormously hardworking and dedicated member". In 1950, he successfully proposed an amendment to the Menzies government's Communist Party Dissolution Bill, reversing the effect of a clause so that the burden of proof was on the government rather than an accused person. However, the bill was subsequently struck down by the High Court. In July 1951, McMahon replaced Philip McBride as Minister for the Navy and Minister for Air. He subsequently approved and oversaw Donald Hardman's proposal to reorganise the Royal Australian Air Force (RAAF) along functional command lines (rather than the previous area command system).

After the 1954 election, McMahon was appointed Minister for Social Services in place of Athol Townley. In January 1956, he was instead made Minister for Primary Industry, an appointment that was seen as a surprise given his lack of experience in agriculture. He effectively became the junior minister to John McEwen, the deputy leader of the Country Party and Minister for Trade. It was hoped by the Country Party (and tacitly accepted by Menzies) that McMahon would simply be a proxy for McEwen on policy matters. However, he managed to preserve the influence and independence of his department, and in fact made a number of cabinet submissions that were contrary to McEwen's wishes. This impressed his colleagues in the Liberal Party, but laid the foundations for the poor relations with the Country Party that would prove challenging later in his career.

McMahon was promoted to Minister for Labour and National Service after the 1958 election, in place of Harold Holt. This brought him firmly into the inner ranks of the Liberal Party, and in terms of cabinet rank placed him among the party's most senior figures in New South Wales. McMahon oversaw the creation and administration of what became the National Service Act 1964, which re-introduced compulsory conscription for 20-year-old males in anticipation of further Australian involvement in South-East Asia. On the labour side of his portfolio, he frequently came into conflict with the leadership of the Australian Council of Trade Unions (ACTU), though there was no major industrial action during his tenure. He attempted to reduce the influence of trade unions known to be controlled by the Communist Party, particularly the Waterside Workers' Federation. In 1964, McMahon was made Vice-President of the Executive Council, further confirming his status within the government.

Under Holt

In 1966, McMahon was elected the Liberal Party of Australia's deputy leader under Harold Holt. During his tenure, he became the Treasurer of Australia and held executive roles with the International Monetary Fund and Asian Development Bank.

Under Gorton

When Holt disappeared in December 1967, McMahon was assumed to be his probable successor. However, John McEwen, interim Prime Minister and leader of the Country Party, announced that he and his party would not serve in a government led by McMahon. McEwen did not state his reasons publicly, but privately he told McMahon he did not trust him. McEwen, an arch-protectionist, correctly suspected that McMahon favoured policies of free trade and deregulation.

McMahon therefore withdrew, and Senator John Gorton won the subsequent party room ballot for party leader and therefore Prime Minister. McMahon remained Treasurer and waited for his chance at a comeback. The Coalition was nearly defeated at the 1969 federal election. After the election, McMahon unsuccessfully challenged for the leadership, but was nonetheless re-elected as deputy leader. He was subsequently demoted from Treasurer to Minister for External Affairs. John McEwen had announced in the lead-up to the spill that he would lift his party's veto on McMahon as prime minister.

In March 1971, the Defence Minister, Malcolm Fraser, resigned from Cabinet and denounced Gorton, who then announced a leadership spill. The ensuing party room vote was tied, and under the party rules of the time this meant the motion was lost and Gorton could have theoretically remained as leader and Prime Minister. Nevertheless, Gorton declared that a tie vote meant he no longer had the confidence of the party, and voluntarily resigned the leadership. McMahon was then elected leader (and thus prime minister), and Gorton was elected deputy leader.

Prime Minister (1971–1972)
McMahon came into office at a bad time for the Coalition, which was increasingly seen as tired and unfocused after 22 years in power. His first problem was Gorton. Since Gorton had been elected as Liberal deputy leader, McMahon was all but forced to name him Defence Minister. This farcical situation came to a head when Gorton published two articles detailing the problems he had with ministers leaking information from cabinet. McMahon forced Gorton's resignation. Billy Snedden was chosen as the new deputy Liberal leader. McMahon found himself dealing with a resurgent Labor Party under Gough Whitlam. Labor had come within four seats of winning government in 1969, and since then had positioned itself as a credible government-in-waiting. Over the next year-and-a-half, McMahon was unable to get the better of Whitlam. McMahon was no match in parliamentary debates for Whitlam, a witty and powerful orator. He frequently found himself on the defensive as Whitlam attacked the increasingly unpopular Vietnam War and advocated radical new policies such as universal health insurance. In a typical instance, McMahon attacked Whitlam for his demands that Australia recognise the People's Republic of China, only to have to back down when U.S President Richard Nixon announced his visit to China. He was not helped by rising inflation, which hurt his reputation as a sound economic manager. Additionally, the Liberal Party was showing severe schisms, which came at an especially bad time since McMahon had, at most, two years before the next election. His voice and appearance also came across badly on television.

In June 1971, McMahon cancelled Gorton's planned nuclear power program, which had included a reactor capable of generating weapons-grade plutonium. He considered it inconsistent with the goals of the Nuclear Non-Proliferation Treaty, signed under Gorton in 1970 and ratified under Whitlam in 1973. McMahon went into 1972 facing a statutory general election. By then, Labor had established a clear lead in the polls and McMahon's approval ratings had dwindled to 28 percent. The press had turned on him so violently that the British psephologist David Butler recalled on a visit to Australia that he could not recall a prime minister in any country being "so comprehensively panned" as McMahon. By then, it was widely perceived that McMahon simply "did not look or sound like a Prime Minister". He waited for as long as he could, but finally called a federal election for 2 December. During the campaign, McMahon was abandoned by some of his own ministers, unheard of in a Westminster system. The Coalition was swept from power on an eight-seat swing. Late on election night, with the result beyond doubt, McMahon conceded defeat, ending the longest unbroken run in government in Australian history. McMahon had been a minister continuously for 21 years and 6 months, a record in the Australian Government that has never been threatened. Only Sir George Pearce and Sir John McEwen had longer overall ministerial service, but their terms were not continuous.

Political journalist Laurie Oakes described McMahon as "devious, nasty, dishonest - he lied all the time and stole things" before describing an incident where McMahon attempted to steal a tape recorder from his radio station by claiming ownership of the device despite it having the radio station's name engraved on it. He concludes by saying that McMahon was a "totally unworthy individual and the fact that he was Prime Minister of this country was a disgrace".

Later parliamentary career (1972–1982)
McMahon's term as prime minister ended on 5 December 1972. He did not immediately resign as Liberal leader, but it soon became clear that there was no support for him to continue.

McMahon became the first Prime Minister to have lost an election and had retained his seat who did not then serve as Leader of the Opposition.

On 20 December, the Liberal Party elected Billy Snedden as his successor. As a mark of respect for his past service, McMahon was included in Snedden's new shadow cabinet (as was John Gorton). However, at his own request he was not allocated a specific portfolio. In an interview with HSV7 in June 1973, McMahon stated that "disloyalty within our own party" was the main reason the Liberals had lost the election. He also said that he had three regrets from his time as prime minister – that he failed to abolish national service, that he had mishandled the 1971 budget, and that he had been a poor communicator.

After the 1974 election, McMahon returned to the backbench for the first time since 1951. In the lead-up to the dismissal of the Whitlam government in 1975, he strongly defended the power of the Senate to block supply. However, he believed that Governor-General John Kerr had acted unconstitutionally in dismissing the prime minister, and said that he would have challenged the decision in the High Court if he had been in Whitlam's position. McMahon believed that those responsible for the "loans affair" – including Whitlam and several of his ministers – had acted illegally and should be prosecuted for their involvement. He assisted Danny Sankey (a private citizen) in bringing a private prosecution against Whitlam, which eventually came before the High Court as Sankey v Whitlam. Malcolm Fraser had promised Kerr that his government would bring no action against its predecessor, and was frustrated by McMahon's actions. In his memoirs, he said: "I knew McMahon was running around up to his tricks ... I couldn't control what he did, but I could make damn sure that the government, my government, did not get involved".

Prior to the 1977 election, McMahon was unsuccessfully challenged for Liberal preselection by John Abel, whose Division of Evans had been abolished in an electoral redistribution. After being re-elected, he became the joint Father of the House of Representatives with Clyde Cameron. He was the sole Father of the House after the 1980 election, winning election for a fourteenth and final time at the age of 72. In his final years in parliament he was often critical of the Fraser government. McMahon left parliament in January 1982, citing dissatisfaction with the 1981 budget as a major factor in his decision to retire before a general election. He nominated future prime minister Malcolm Turnbull as his preferred successor in Lowe, but the Liberal Party chose another candidate Philip Taylor. The by-election was won by the Labor Party on a 9.4-point swing.

He was the last former Prime Minister to be reelected to Parliament until Kevin Rudd in 2010.

Final years and death
In retirement, McMahon devoted much of his time to working on his memoirs, which he planned to title A Liberal View. They were rejected by six publishers, and reviewers (who included Barry Jones and Phillip Adams) considered them to be poorly written and overly detailed. In 1984, McMahon endorsed Bob Hawke and the Labor Party for re-election over the Coalition, which he said would not be ready for government for another four or five years. Later that year, he described Andrew Peacock's hold on the Liberal leadership as "very, very fragile", and tacitly endorsed John Howard as a future leader.

In his final years, McMahon underwent a series of operations related to skin cancer. He died in his sleep at St Luke's Private Hospital, Potts Point, on the morning of 31 March 1988. His remains were cremated at the Northern Suburbs Crematorium. A state memorial service was held at St Andrew's Cathedral, Sydney, on 8 April, with the eulogy given by David Fairbairn.

Personal life
In 1965, aged 57, McMahon married Sonia Rachel Hopkins, who was then aged 32. McMahon had proposed six months after the pair first met. The wedding was held three months later at St Mark's Church, Darling Point, followed by a reception for 400 people at the Royal Sydney Golf Club. She would survive him by over twenty years, dying aged 77 on 2 April 2010.

They had three children; Melinda, Julian and Deborah. Julian is an actor and model while Melinda and Deborah lead largely private lives.

Throughout his life there were also frequent rumours that he was homosexual. The suggestion was repeatedly denied by Lady McMahon; one occasion in the 1970s resulted in an infamous tabloid headline "My Billy's No Poofter – Sonia Tells".

Religion
McMahon was an Anglican. He did not have a strong religious upbringing – his father was a lapsed Catholic and self-described "rationalist", while his mother's family were Anglican. McMahon developed an interest in theology as a teenager, and read widely on the subject over the rest of his life. He cited the works of William Temple as a major influence. McMahon was one of the few contemporary politicians to speak publicly on the connection between their religious and political beliefs. In 1953, he gave an address to the Australian Institute of Political Science in which he explained how he believed Christian doctrines necessitated parliamentary democracy and a market economy.

Evaluation
McMahon is often ranked among Australia's worst prime ministers. In 2001, five out of six historians surveyed by Australian Financial Review ranked him among their worst five prime ministers. Similarly, The Age surveyed eight historians in 2004 and all but one ranked McMahon as Australia's worst prime minister since World War II. Some of McMahon's most prominent critics have been those who served with him in cabinet. John Gorton called him "utterly untrustworthy", while Doug Anthony said he was "just not big enough for the job". Malcolm Fraser said he "had an insatiable ambition [...] he wasn't immoral, he was totally amoral". Billy Snedden considered McMahon "conspiratorial, devious, untrustworthy", and Paul Hasluck viewed him as "disloyal, devious, dishonest, untrustworthy, petty, cowardly", in his diaries referring to him as "that treacherous bastard".

McMahon was nicknamed "Billy the Leak" for his willingness to divulge intimate and confidential information to the media. Despite this, he was disliked by many journalists and political commentators. Donald Horne called him "perhaps the silliest prime minister we ever had", and Peter Ryan said that "McMahon's way of politics was one of lying and leaking, conniving and conspiring, deceit and double-crossing". Malcolm Mackerras thought that he had "no achievements beyond actually getting the top job". Laurie Oakes, who spent over 50 years in the Canberra Press Gallery, viewed McMahon as "a liar and a sneak" and rated him as the worst prime minister he had worked with. Oakes recalled that he had continued leaking cabinet discussions even after becoming prime minister, and accused him of once having stolen a tape recorder.

Some writers have defended McMahon's reputation, arguing that he was a skilled politician who has been unfairly scapegoated for an almost inevitable election loss. According to John Hawkins, McMahon was "grudgingly admired for his energy and diligence", and generally acknowledged as having a mastery of economic policy. Mungo MacCallum, while noting that he left no lasting achievements, called his prime ministership a "brief but cheerful interlude" and praised him for leaving office with good grace. Marian Simms compared McMahon to Richard Nixon, suggesting that his character traits have been overemphasised, while Troy Bramston viewed him as "a prime minister who clearly understood the challenge of the times and was fighting to get his ship back on course" when he was forced out of office. Andrew Peacock, who served in McMahon's ministry, said that McMahon was "much better than he has been painted... He is somewhat ill-treated by history", and described him as "difficult, irascible, nervous yet capable". In his memoirs, Gough Whitlam wrote that McMahon was "an extraordinarily skilful, resourceful and tenacious politician ... had he been otherwise, the ALP victory in December 1972 would have been more convincing than it was".

Honours

McMahon was appointed a Privy Counsellor in 1966, a Member of the Order of the Companions of Honour in the 1972 New Year Honours, and a Knight Grand Cross of the Order of St Michael and St George in the Queen's Birthday Honours of 1977.

Following the 2009 redistribution of New South Wales federal electorates, the Division of Prospect was renamed the Division of McMahon starting at the 2010 federal election.

title: William McMahon


text:
Van de Graaff generator

A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate electric charge on a hollow metal globe on the top of an insulated column, creating very high electric potentials. It produces very high voltage direct current (DC) electricity at low current levels. It was invented by American physicist Robert J. Van de Graaff in 1929. The potential difference achieved by modern Van de Graaff generators can be as much as 5 megavolts. A tabletop version can produce on the order of 100 kV and can store enough energy to produce visible electric sparks. Small Van de Graaff machines are produced for entertainment, and for physics education to teach electrostatics; larger ones are displayed in some science museums.

The Van de Graaff generator was originally developed as a particle accelerator for physics research, as its high potential can be used to accelerate subatomic particles to great speeds in an evacuated tube. It was the most powerful type of accelerator until the cyclotron was developed in the early 1930s. Van de Graaff generators are still used as accelerators to generate energetic particle and X-ray beams for nuclear research and nuclear medicine.

The voltage produced by an open-air Van de Graaff machine is limited by arcing and corona discharge to about 5 MV. Most modern industrial machines are enclosed in a pressurized tank of insulating gas; these can achieve potentials as large as about 25 MV.

Background
The concept of an electrostatic generator in which charge is mechanically transported in small amounts into the interior of a high-voltage electrode originated with the Kelvin water dropper, invented in 1867 by William Thomson (Lord Kelvin), in which charged drops of water fall into a bucket with the same polarity charge, adding to the charge. In a machine of this type, the gravitational force moves the drops against the opposing electrostatic field of the bucket. Kelvin himself first suggested using a belt to carry the charge instead of water. The first electrostatic machine that used an endless belt to transport charge was constructed in 1872 by Augusto Righi. It used an india rubber belt with wire rings along its length as charge carriers, which passed into a spherical metal electrode. The charge was applied to the belt from the grounded lower roller by electrostatic induction using a charged plate. John Gray also invented a belt machine about 1890. Another more complicated belt machine was invented in 1903 by Juan Burboa A more immediate inspiration for Van de Graaff was a generator W. F. G. Swann was developing in the 1920s in which charge was transported to an electrode by falling metal balls, thus returning to the principle of the Kelvin water dropper.

Initial development
The Van de Graaff generator was developed, starting in 1929, by physicist Robert J. Van de Graaff at Princeton University, with help from colleague Nicholas Burke. The first model was demonstrated in October 1929. The first machine used an ordinary tin can, a small motor, and a silk ribbon bought at a five-and-dime store. After that, he went to the chairman of the physics department requesting $100 to make an improved version. He did get the money, with some difficulty. By 1931, he could report achieving 1.5 million volts, saying "The machine is simple, inexpensive, and portable. An ordinary lamp socket provides the only power needed." According to a patent application, it had two 60-cm-diameter charge-accumulation spheres mounted on borosilicate glass columns 180 cm high; the apparatus cost $90 in 1931.

Van de Graaff applied for a second patent in December 1931, which was assigned to Massachusetts Institute of Technology in exchange for a share of net income; the patent was later granted.

In 1933, Van de Graaff built a 40 ft (12 m) model at MIT's Round Hill facility, the use of which was donated by Colonel Edward H. R. Green. One consequence of the location of this generator in an aircraft hangar was the "pigeon effect": arcing from accumulated droppings on the outer surface of the spheres.

Higher energy machines
In 1937, the Westinghouse Electric company built a 65 ft machine, the Westinghouse Atom Smasher capable of generating 5 MeV in Forest Hills, Pennsylvania. It marked the beginning of nuclear research for civilian applications. It was decommissioned in 1958 and was partially demolished in 2015. (The enclosure was laid on its side for safety reasons.)

A more recent development is the tandem Van de Graaff accelerator, containing one or more Van de Graaff generators, in which negatively charged ions are accelerated through one potential difference before being stripped of two or more electrons, inside a high-voltage terminal, and accelerated again. An example of a three-stage operation has been built in Oxford Nuclear Laboratory in 1964 of a 10 MV single-ended "injector" and a 6 MV EN tandem.

By the 1970s, as much as 14 MV could be achieved at the terminal of a tandem that used a tank of high-pressure sulfur hexafluoride (SF6) gas to prevent sparking by trapping electrons. This allowed the generation of heavy ion beams of several tens of MeV, sufficient to study light-ion direct nuclear reactions. The greatest potential sustained by a Van de Graaff accelerator is 25.5 MV, achieved by the tandem in the Holifield Radioactive Ion Beam Facility in Oak Ridge National Laboratory.

A further development is the pelletron, where the rubber or fabric belt is replaced by a chain of short conductive rods connected by insulating links, and the air-ionizing electrodes are replaced by a grounded roller and inductive charging electrode. The chain can be operated at a much greater velocity than a belt, and both the voltage and currents attainable are much greater than with a conventional Van de Graaff generator. The 14 UD Heavy Ion Accelerator at the Australian National University houses a 15 MV pelletron. Its chains are more than 20 m long and can travel faster than 50 km/h.

The Nuclear Structure Facility (NSF) at Daresbury Laboratory was proposed in the 1970s, commissioned in 1981, and opened for experiments in 1983. It consisted of a tandem Van de Graaff generator operating routinely at 20 MV, housed in a distinctive building 70 m high. During its lifetime, it accelerated 80 different ion beams for experimental use, ranging from protons to uranium. A particular feature was the ability to accelerate rare isotopic and radioactive beams. Perhaps the most important discovery made using the NSF was that of super-deformed nuclei. These nuclei, when formed from the fusion of lighter elements, rotate very rapidly. The pattern of gamma rays emitted as they slow down provided detailed information about the inner structure of the nucleus. Following financial cutbacks, the NSF closed in 1993.

Description

A simple Van de Graaff generator consists of a belt of rubber (or a similar flexible dielectric material) moving over two rollers of differing material, one of which is surrounded by a hollow metal sphere. A comb-shaped metal electrode with sharp points (2 and 7 in the diagram), is positioned near each roller. The upper comb (2) is connected to the sphere, and the lower one (7) to ground. When a motor is used to drive the belt, the triboelectric effect causes the transfer of electrons from the dissimilar materials of the belt and the two rollers. In the example shown, the rubber of the belt will become negatively charged while the acrylic glass of the upper roller will become positively charged. The belt carries away negative charge on its inner surface while the upper roller accumulates positive charge.

Next, the strong electric field surrounding the positive upper roller (3) induces a very high electric field near the points of the nearby comb (2). At the points of the comb, the field becomes strong enough to ionize air molecules. The electrons from the air molecules are attracted to the outside of the belt, while the positive ions go to the comb. At the comb they are neutralized by electrons from the metal, thus leaving the comb and the attached outer shell (1) with fewer net electrons and a net positive charge. By Gauss's law (as illustrated in the Faraday ice pail experiment), the excess positive charge is accumulated on the outer surface of the outer shell, leaving no electric field inside the shell. Continuing to drive the belt causes further electrostatic induction, which can build up large amounts of charge on the shell. Charge will continue to accumulate until the rate of charge leaving the sphere (through leakage and corona discharge) equals the rate at which new charge is being carried into the sphere by the belt.

Outside the terminal sphere, a high electric field results from the high voltage on the sphere, which would prevent the addition of further charge from the outside. However, since electrically charged conductors do not have any electric field inside, charges can be added continuously from the inside without needing to overcome the full potential of the outer shell.

The larger the sphere and the farther it is from ground, the higher its peak potential. The sign of the charge (positive or negative) can be controlled by the selection of materials for the belt and rollers. Higher potentials on the sphere can also be achieved by using a voltage source to charge the belt directly, rather than relying solely on the triboelectric effect.

A Van de Graaff generator terminal does not need to be sphere-shaped to work, and in fact, the optimum shape is a sphere with an inward curve around the hole where the belt enters. A rounded terminal minimizes the electric field around it, allowing greater potentials to be achieved without ionization of the air, or other dielectric gas, surrounding it. Since a Van de Graaff generator can supply the same small current at almost any level of electrical potential, it is an example of a nearly ideal current source.

The maximal achievable potential is roughly equal to the sphere radius R multiplied by the electric field Emax at which corona discharges begin to form within the surrounding gas. For air at standard temperature and pressure (STP) the breakdown field is about $5 MeV$. Therefore, a polished spherical electrode 30 cm in diameter could be expected to develop a maximal voltage Vmax = R·Emax of about $30 kV/cm$. This explains why Van de Graaff generators are often made with the largest possible diameter.

Use as a particle accelerator
The initial motivation for the development of the Van de Graaff generator was as a source of high voltage to accelerate particles for nuclear physics experiments. The high potential difference between the surface of the terminal and ground results in a corresponding electric field. When an ion source is placed near the surface of the sphere (typically within the sphere itself) the field will accelerate charged particles of the appropriate sign away from the sphere. By insulating the generator with pressurized gas, the breakdown voltage can be raised, increasing the maximum energy of accelerated particles.

Tandem accelerators
Particle-beam Van de Graaff accelerators are often used in a "tandem" configuration with the high potential terminal located at the center of the machine. Negatively charged ions are injected at one end, where they are accelerated by attractive force toward the terminal. When the particles reach the terminal, they are stripped of some electrons to make them positively charged, and are subsequently accelerated by repulsive forces away from the terminal. This configuration results in two accelerations for the cost of one Van de Graaff generator and has the added advantage of leaving the ion source instrumentation accessible near ground potential.

Pelletron
The pelletron is a style of tandem accelerator designed to overcome some of the disadvantages of using a belt to transfer charge to the high voltage terminal. In the pelletron, the belt is replaced with "pellets", metal spheres joined by insulating links into a chain. This chain of spheres serves the same function as the belt in a traditional Van de Graff accelerator – to convey charge to the high voltage terminal. The separate charged spheres and higher durability of the chain mean that higher voltages can be achieved at the high voltage terminal, and charge can be conveyed to the terminal more quickly.

Entertainment and educational generators
The largest air-insulated Van de Graaff generator in the world, built by Dr. Van de Graaff in the 1930s, is now displayed permanently at Boston's Museum of Science. With two conjoined 4.5 m aluminium spheres standing on columns 22 ft tall, this generator can often obtain 2 MV (2 million volts). Shows using the Van de Graaff generator and several Tesla coils are conducted two to three times a day. Many science museums, such as the American Museum of Science and Energy, have small-scale Van de Graaff generators on display, and exploit their static-producing qualities to create "lightning" or make people's hair stand up. Van de Graaff generators are also used in schools and science shows.

Comparison with other electrostatic generators
Other electrostatic machines such as the Wimshurst machine or Bonetti machine work similarly to the Van De Graaff generator; charge is transported by moving plates, disks, or cylinders to a high voltage electrode. For these generators, however, corona discharge from exposed metal parts at high potentials and poorer insulation result in smaller voltages. In an electrostatic generator, the rate of charge transported (current) to the high-voltage electrode is very small. After the machine is started, the voltage on the terminal electrode increases until the leakage current from the electrode equals the rate of charge transport. Therefore, leakage from the terminal determines the maximum voltage attainable. In the Van de Graaff generator, the belt allows the transport of charge into the interior of a large hollow spherical electrode. This is the ideal shape to minimize leakage and corona discharge, so the Van de Graaff generator can produce the greatest voltage. This is why the Van de Graaff design has been used for all electrostatic particle accelerators. In general, the larger the diameter and the smoother the sphere is, the higher the voltage that can be achieved.

Patents

 * — "Electrostatic Generator"
 * — "Apparatus For Reducing Electron Loading In Positive-Ion Accelerators"

title: Van de Graaff generator


text:
Cysteine

Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula HOOC\sCH(\sNH2)\sCH2\sSH. The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. Cysteine is chiral, but interestingly, both D and L -cysteine are found in nature with D -cysteine having been found in developing brain (see Semenza et al., 2021). Cysteine is named after its discovery in urine, which comes from the urinary bladder or cyst, from kystis "bladder".

The thiol is susceptible to oxidation to give the disulfide derivative cystine, which serves an important structural role in many proteins. In this case, the symbol Cyx is sometimes used. The deprotonated form can generally be described by the symbol Cym as well.

When used as a food additive, cysteine has the E number E920.

Cysteine is encoded by the codons UGU and UGC.

Structure
Like other amino acids (not as a residue of a protein), cysteine exists as a zwitterion. Cysteine has chirality in the older / notation based on homology to - and -glyceraldehyde. In the newer R/S system of designating chirality, based on the atomic numbers of atoms near the asymmetric carbon, cysteine (and selenocysteine) have R chirality, because of the presence of sulfur (or selenium) as a second neighbor to the asymmetric carbon atom. The remaining chiral amino acids, having lighter atoms in that position, have S chirality. Replacing sulfur with selenium gives selenocysteine.

Dietary sources
Cysteinyl is a residue in high-protein foods. Some foods considered rich in cysteine include poultry, eggs, beef, and whole grains. In high-protein diets, cysteine may be partially responsible for reduced blood pressure and stroke risk. Although classified as a nonessential amino acid, in rare cases, cysteine may be essential for infants, the elderly, and individuals with certain metabolic diseases or who suffer from malabsorption syndromes. Cysteine can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available.

Industrial sources
The majority of -cysteine is obtained industrially by hydrolysis of animal materials, such as poultry feathers or hog hair. Despite widespread belief otherwise, little evidence shows that human hair is used as a source material and its use is explicitly banned for food additives and cosmetic products in the European Union. Synthetically produced -cysteine, compliant with Jewish kosher and Muslim halal laws, is also available, albeit at a higher price. The synthetic route involves fermentation using a mutant of E. coli. Evonik (formerly Degussa) introduced a route from substituted thiazolines. Following this technology, -cysteine is produced by the hydrolysis of racemic 2-amino-Δ2-thiazoline-4-carboxylic acid using Pseudomonas thiazolinophilum.

Biosynthesis
In animals, biosynthesis begins with the amino acid serine. The sulfur is derived from methionine, which is converted to homocysteine through the intermediate S-adenosylmethionine. Cystathionine beta-synthase then combines homocysteine and serine to form the asymmetrical thioether cystathionine. The enzyme cystathionine gamma-lyase converts the cystathionine into cysteine and alpha-ketobutyrate. In plants and bacteria, cysteine biosynthesis also starts from serine, which is converted to O-acetylserine by the enzyme serine transacetylase. The enzyme cysteine synthase, using sulfide sources, converts this ester into cysteine, releasing acetate.

Biological functions
The cysteine sulfhydryl group is nucleophilic and easily oxidized. The reactivity is enhanced when the thiol is ionized, and cysteine residues in proteins have pKa values close to neutrality, so are often in their reactive thiolate form in the cell. Because of its high reactivity, the sulfhydryl group of cysteine has numerous biological functions.

Precursor to the antioxidant glutathione
Due to the ability of thiols to undergo redox reactions, cysteine and cysteinyl residues have antioxidant properties. Its antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans and other organisms. The systemic availability of oral glutathione (GSH) is negligible; so it must be biosynthesized from its constituent amino acids, cysteine, glycine, and glutamic acid. While glutamic acid is usually sufficient because amino acid nitrogen is recycled through glutamate as an intermediary, dietary cysteine and glycine supplementation can improve synthesis of glutathione.

Precursor to iron-sulfur clusters
Cysteine is an important source of sulfide in human metabolism. The sulfide in iron-sulfur clusters and in nitrogenase is extracted from cysteine, which is converted to alanine in the process.

Metal ion binding
Beyond the iron-sulfur proteins, many other metal cofactors in enzymes are bound to the thiolate substituent of cysteinyl residues. Examples include zinc in zinc fingers and alcohol dehydrogenase, copper in the blue copper proteins, iron in cytochrome P450, and nickel in the [NiFe]-hydrogenases. The sulfhydryl group also has a high affinity for heavy metals, so that proteins containing cysteine, such as metallothionein, will bind metals such as mercury, lead, and cadmium tightly.

Roles in protein structure
In the translation of messenger RNA molecules to produce polypeptides, cysteine is coded for by the UGU and UGC codons.

Cysteine has traditionally been considered to be a hydrophilic amino acid, based largely on the chemical parallel between its sulfhydryl group and the hydroxyl groups in the side chains of other polar amino acids. However, the cysteine side chain has been shown to stabilize hydrophobic interactions in micelles to a greater degree than the side chain in the nonpolar amino acid glycine and the polar amino acid serine. In a statistical analysis of the frequency with which amino acids appear in various proteins, cysteine residues were found to associate with hydrophobic regions of proteins. Their hydrophobic tendency was equivalent to that of known nonpolar amino acids such as methionine and tyrosine (tyrosine is polar aromatic but also hydrophobic ), those of which were much greater than that of known polar amino acids such as serine and threonine. Hydrophobicity scales, which rank amino acids from most hydrophobic to most hydrophilic, consistently place cysteine towards the hydrophobic end of the spectrum, even when they are based on methods that are not influenced by the tendency of cysteines to form disulfide bonds in proteins. Therefore, cysteine is now often grouped among the hydrophobic amino acids, though it is sometimes also classified as slightly polar, or polar.

Most cysteine residues are covalently bonded to other cysteine residues to form disulfide bonds, which play an important role in the folding and stability of some proteins, usually proteins secreted to the extracellular medium. Since most cellular compartments are reducing environments, disulfide bonds are generally unstable in the cytosol with some exceptions as noted below.

Disulfide bonds in proteins are formed by oxidation of the sulfhydryl group of cysteine residues. The other sulfur-containing amino acid, methionine, cannot form disulfide bonds. More aggressive oxidants convert cysteine to the corresponding sulfinic acid and sulfonic acid. Cysteine residues play a valuable role by crosslinking proteins, which increases the rigidity of proteins and also functions to confer proteolytic resistance (since protein export is a costly process, minimizing its necessity is advantageous). Inside the cell, disulfide bridges between cysteine residues within a polypeptide support the protein's tertiary structure. Insulin is an example of a protein with cystine crosslinking, wherein two separate peptide chains are connected by a pair of disulfide bonds.

Protein disulfide isomerases catalyze the proper formation of disulfide bonds; the cell transfers dehydroascorbic acid to the endoplasmic reticulum, which oxidizes the environment. In this environment, cysteines are, in general, oxidized to cystine and are no longer functional as a nucleophiles.

Aside from its oxidation to cystine, cysteine participates in numerous post-translational modifications. The nucleophilic sulfhydryl group allows cysteine to conjugate to other groups, e.g., in prenylation. Ubiquitin ligases transfer ubiquitin to its pendant, proteins, and caspases, which engage in proteolysis in the apoptotic cycle. Inteins often function with the help of a catalytic cysteine. These roles are typically limited to the intracellular milieu, where the environment is reducing, and cysteine is not oxidized to cystine.

Applications
Cysteine, mainly the -enantiomer, is a precursor in the food, pharmaceutical, and personal-care industries. One of the largest applications is the production of flavors. For example, the reaction of cysteine with sugars in a Maillard reaction yields meat flavors. -Cysteine is also used as a processing aid for baking.

In the field of personal care, cysteine is used for permanent-wave applications, predominantly in Asia. Again, the cysteine is used for breaking up the disulfide bonds in the hair's keratin.

Cysteine is a very popular target for site-directed labeling experiments to investigate biomolecular structure and dynamics. Maleimides selectively attach to cysteine using a covalent Michael addition. Site-directed spin labeling for EPR or paramagnetic relaxation-enhanced NMR also uses cysteine extensively.

Reducing toxic effects of alcohol
Cysteine has been proposed as a preventive or antidote for some of the negative effects of alcohol, including liver damage and hangover. It counteracts the poisonous effects of acetaldehyde. Cysteine supports the next step in metabolism, which turns acetaldehyde into acetic acid.

In a rat study, test animals received an LD90 dose of acetaldehyde. Those that received cysteine had an 80% survival rate; when both cysteine and thiamine were administered, all animals survived. The control group had a 10% survival rate.

In 2020 an article was published that suggests L-cysteine might also work in humans.

N-Acetylcysteine
N-Acetyl--cysteine is a derivative of cysteine wherein an acetyl group is attached to the nitrogen atom. This compound is sold as a dietary supplement, and used as an antidote in cases of acetaminophen overdose.

Sheep
Cysteine is required by sheep to produce wool. It is an essential amino acid that is taken in from their feed. As a consequence, during drought conditions, sheep produce less wool; however, transgenic sheep that can make their own cysteine have been developed.

Chemical reactions
Being multifunctional, cysteine undergoes a variety of reactions. Much attention has focused on protecting the sulfhydryl group. Methylation of cysteine gives S-methylcysteine. Treatment with formaldehyde gives the thiazolidine thioproline. Cysteine forms a variety of coordination complexes upon treatment with metal ions.

Safety
Relative to most other amino acids, cysteine is much more toxic.

Dietary restrictions
The animal-originating sources of -cysteine as a food additive are a point of contention for people following dietary restrictions such as kosher, halal, vegan, or vegetarian. To avoid this problem, -cysteine can also be sourced from microbial or other synthetic processes.

History
In 1884 German chemist Eugen Baumann found that when cystine was treated with a reducing agent, cystine revealed itself to be a dimer of a monomer which he named "cysteïne".

title: Cysteine


text:
Liberty (disambiguation)

Liberty is the ability to do as one pleases, or have the power and resources to fulfill one's purposes.

Liberty may also refer to:

Films and television

 * Liberty (serial), a 1916 film serial
 * Liberty (1929 film), a short film starring Laurel and Hardy
 * Liberty (1986 film), a television historical drama
 * Liberty!, a 1997 documentary about the American Revolutionary War

Magazines

 * Liberty (1881–1908 periodical), an anarchist political magazine
 * Liberty (Adventist magazine), a religious liberty magazine
 * Liberty (general interest magazine), a magazine published from 1924 to 1950
 * Liberty (libertarian magazine), a political magazine published from 1987
 * Liberties, an American literary magazine edited by Leon Wieseltier

Newspapers

 * Liberty (British newspaper), an anarcho-communist paper published from 1894 to 1896
 * Liberty (Thai newspaper), a defunct English-language newspaper published in Thailand

Others

 * Liberty (manga), a 2017 manga by Izumi Kitta
 * "Liberty" (poem), a 1942 poem by Paul Éluard
 * "Liberty", a 1730 poem by James Thomson
 * Liberty! The Saga of Sycamore Shoals, an outdoor play performed seasonally in Tennessee, US
 * Liberty Liberty!, a 2005 Japanese manga
 * Liberty style, the Italian variant of Art Nouveau
 * Liberty/Libertà, a 2019 exhibition by the sculptor Martin Puryear at the Venice Biennale's American pavilion
 * On Liberty, an 1859 political philosophy paper written by John Stuart Mill
 * Liberty, a dachshund character in PAW Patrol and PAW Patrol: The Movie

Business

 * Liberty (department store), a London store founded in 1875 by Arthur Lasenby Liberty
 * The Liberty, a shopping centre in Havering, London, England
 * Liberty 2, a former name of The Mercury Mall, an adjacent shopping centre
 * Liberty Aerospace, a manufacturer of general aviation aircraft
 * Liberty Alliance, a standards consortium for identity management
 * Liberty Broadcasting System, a defunct radio network
 * Liberty Corporation, a defunct insurance and media company, based in South Carolina, United States
 * Liberty Global, a media company and broadband provider
 * Liberty Holdings Limited, a financial services company in South Africa
 * Liberty Media, holding company for the media interests of John C. Malone
 * Liberty Medical, a company that sells diabetes testers
 * Liberty Mutual, a large United States insurance company
 * Liberty Oil, Australian petrol retailer
 * Liberty Reserve, a former digital currency service
 * Liberty Safe, a safe manufacturer located in the United States founded in 1988
 * Liberty Shoes, a shoe company based in India, established in 1954
 * Liberty Steel Group, a British industrial and metals company

Albums

 * Liberty (Duran Duran album), 1990
 * Liberty, a 1995 album by The Guess Who
 * Liberty (Lindi Ortega album), 2018
 * Liberty (Miliyah Kato album), 2016
 * Liberty! (album), a 1997 album by Mark O'Connor

Songs

 * "Liberty", a song by Janis Ian from Present Company
 * "Liberty", a song by Heavenly from Virus
 * "Liberty", a song by John 5 from Vertigo
 * "Liberty", a song by Vertical Horizon from There and Back Again
 * "Liberty", a song by the Grateful Dead from So Many Roads (1965–1995) and Road Trips Volume 2 Number 4
 * "Liberty", a song by Journey from Time3

Other uses

 * Liberty Music Shop Records, a record label
 * Liberty Records, a former US record label
 * Liberty X (formerly Liberty), a pop group founded on the British reality show Popstars

Given name

 * Liberty Hyde Bailey (1858–1954) American botanist
 * Liberty Barnes, American sociologist, ethnographer, and writer
 * Liberty Bartlett (1810–unknown)
 * Liberty Billings (1823–1877), American officer in the Union Army, minister, and politician
 * Liberty DeVitto (born 1950), American rock drummer
 * Liberty Ellman (born 1971), London-born American jazz guitarist
 * Liberty Heap (born 2003), English cricketer
 * Liberty Ma Mya Yin (1904–1945), Burmese dancer and singer
 * Liberty Poole (born 1999), English television personality and model
 * Liberty Ross (born 1978), English model
 * Liberty Silver (born c. 1961), Canadian singer

Mononym

 * Liberty, one half of the professional wrestling tag-team The American Eagles
 * Liberty, a female professional wrestler from the Gorgeous Ladies of Wrestling

Surname

 * Arthur Lasenby Liberty (1843–1917), English merchant and founder of Liberty & Co.

Fictional characters

 * Liberty Valance, title character of the film The Man Who Shot Liberty Valance
 * Liberty Savage, a character from the British Channel 4 soap opera Hollyoaks
 * Liberty Van Zandt, a character from the Canadian television drama Degrassi: The Next Generation

Places

 * The Liberties, Dublin, a district in the south-west inner city of Dublin, Ireland
 * Liberty, Saskatchewan, Canada

United States

 * Liberty City (disambiguation)
 * Liberty County (disambiguation)
 * Liberty Township (disambiguation)
 * Liberty, Arizona
 * Liberty, California, a community in Sonoma County
 * Liberty, San Joaquin County, California, a ghost town
 * Liberty, Idaho
 * Liberty, Illinois
 * Liberty, Saline County, Illinois
 * Liberty, Indiana
 * Liberty, Kansas
 * Liberty, Kentucky
 * Garden Village, Kentucky or Liberty, a community in Pike County
 * Liberty, Maine
 * Liberty, Mississippi
 * Liberty, Missouri
 * Liberty, Nebraska
 * Liberty (town), New York, a town in Sullivan County, New York
 * Liberty (village), New York, a village in Sullivan County, New York
 * Liberty, North Carolina
 * Liberty, Ohio
 * Liberty, Oklahoma
 * Liberty, Pennsylvania (disambiguation), three places
 * Liberty Mountain Resort, a ski area located in Carroll Valley, Pennsylvania
 * Liberty, South Carolina
 * Liberty, Tennessee
 * Liberty, Texas
 * Liberty, Utah
 * Tridell, Utah, also called Liberty
 * Liberty, Washington
 * Liberty, West Virginia
 * Liberty, Wisconsin (disambiguation), five places
 * West Liberty (disambiguation)

Water transport

 * Liberty ship, a design of cargo ship mass-produced in the United States during World War II
 * Liberty (ship), a list of ships named Liberty
 * Liberty pass, for shore leave
 * HMS Liberty (J391), a World War II minesweeper

Aviation

 * Liberty (rocket), a proposed rocket for crew and cargo
 * Airco DH.4, at one point called "Liberty Planes"
 * Associated Air Liberty 181, an American aircraft design
 * Rolls-Royce AE 1107C-Liberty aeroengine

Land transport

 * Avelia Liberty, a high-speed train built by Alstom for the North American market
 * Liberty Motor Car, an American car manufacturer from 1916 to 1923
 * Liberty truck, a former United States cargo vehicle
 * Jeep Liberty, an SUV
 * Liberty L-12, a United States First World War V12 aero-engine also used in 1930s British tanks as the Nuffield Liberty
 * Tank Mark VIII, the Mark VIII or "Liberty", an Anglo-American development of the main British tank of the First World War

Other uses

 * Liberty (advocacy group), a United Kingdom pressure group that campaigns to protect civil liberties and human rights
 * Liberty (apple), a hybrid apple cultivar
 * Liberty (cucumber), used for pickling
 * Liberty (division), a largely medieval English administrative unit
 * Liberty (dog) (1974–1984), golden retriever pet of Gerald Ford
 * "Liberty" (Fringe), an episode of the television series Fringe
 * Liberty (Go), an empty space adjacent to a group of stones in the board game Go
 * Liberty (Muni), a station on the San Francisco Municipal Railway
 * Liberty (personification), the anthropomorphic portrayal of the concept of liberty, often as a goddess
 * Liberty Bell, an iconic symbol of American independence located in Philadelphia
 * Liberty University, a Christian research university in Lynchburg, Virginia
 * Liberty Flames and Lady Flames, the university's athletic program
 * New York Liberty, a women's basketball team
 * Statue of Liberty, an 1886 colossal neoclassical sculpture on Liberty Island in the middle of New York Harbor, in Manhattan, New York City
 * Liberty, a term used for shore leave in the United States Coast Guard, United States Marine Corps, and United States Navy
 * Liberty, a cheerleading stunt

title: Liberty (disambiguation)