Usefulness.

A 2016 systematic review indicates that using toothpaste when brushing the teeth has no impact on the level of plaque removal.

Ingredients.

In addition to 20%–42% water, toothpastes are derived from a variety of components, the three main ones being abrasives, fluoride, and detergents.

Abrasives.

Abrasives constitute at least 50% of a typical toothpaste. These insoluble particles are designed to help remove plaque from the teeth. The removal of plaque and calculus prevents the accumulation of tartar and is widely claimed to help minimize cavities and periodontal disease, although the clinical significance of this benefit is debated. Representative abrasives include particles of aluminum hydroxide (Al(OH)), calcium carbonate (CaCO), various calcium hydrogen phosphates, various silicas and zeolites, and hydroxyapatite (Ca(PO)OH).  Abrasives, like the dental polishing agents used in dentists' offices, also cause a small amount of enamel erosion which is termed "polishing" action. Some brands contain powdered white mica, which acts as a mild abrasive, and also adds a cosmetically pleasing glittery shimmer to the paste. The polishing of teeth removes stains from tooth surfaces, but has not been shown to improve dental health over and above the effects of the removal of plaque and calculus.  The abrasive effect of toothpaste is indicated by its RDA value. Too high RDA values are deleterious. Some dentists recommend toothpaste with an RDA value no higher than 50 for daily use.

Fluorides.

Fluoride in various forms is the most popular active ingredient in toothpaste to prevent cavities. Fluoride is present in small amounts in plants, animals, and some natural water sources. The additional fluoride in toothpaste has beneficial effects on the formation of dental enamel and bones. Sodium fluoride (NaF) is the most common source of fluoride, but stannous fluoride (SnF), olaflur (an organic salt of fluoride), and sodium monofluorophosphate (NaPOF) are also used. Stannous fluoride has been shown to be more effective than sodium fluoride in reducing the incidence of dental caries and controlling gingivitis, but causes somewhat more surface stains.  Much of the toothpaste sold in the United States has 1,000 to 1,100 parts per million fluoride. In European countries, such as the UK or Greece, the fluoride content is often higher; a NaF content of 0.312% w/w (1,450 ppm fluoride) is common. All of these concentrations are likely to prevent tooth decay, according to a 2019 Cochrane review. Concentrations below 1,000 ppm are not likely to be preventive, and the preventive effect increases with concentration. Clinical trials support the use of high fluoride dentifrices, as it was found to reduce the amount of plaque accumulated, decrease the number of mutans streptococci and lactobacilli and possibly promote calcium fluoride deposits to a higher degree than after the use of traditional fluoride containing dentifrices. However, these effects must be balanced with the increased risk of harm at higher concentrations.

Surfactants.

Many, although not all, toothpastes contain sodium lauryl sulfate (SLS) or related surfactants (detergents). SLS is found in many other personal care products as well, such as shampoo, and is mainly a foaming agent, which enables uniform distribution of toothpaste, improving its cleansing power.

Other components.

Antibacterial agents.

Triclosan, an antibacterial agent, is a common toothpaste ingredient in the United Kingdom. Triclosan or zinc chloride prevent gingivitis and, according to the American Dental Association, helps reduce tartar and bad breath. A 2006 review of clinical research concluded there was evidence for the effectiveness of 0.30% triclosan in reducing plaque and gingivitis. Another Cochrane review in 2013 has found that triclosan achieved a 22% reduction in plaque, and in gingivitis, a 48% reduction in bleeding gums. However, there was insufficient evidence to show a difference in fighting periodontitis and there was no evidence either of any harmful effects associated with the use of triclosan toothpastes for more than 3 years. The evidence relating to plaque and gingivitis was considered to be of moderate quality while for periodontitis was low quality.

Flavorants.

Toothpaste comes in a variety of colors and flavors, intended to encourage use of the product. The three most common flavorants are peppermint, spearmint, and wintergreen. Toothpaste flavored with peppermint-anise oil is popular in the Mediterranean region. These flavors are provided by the respective oils, e.g. peppermint oil. More exotic flavors include Anethole anise, apricot, bubblegum, cinnamon, fennel, lavender, neem, ginger, vanilla, lemon, orange, and pine. Alternatively, unflavored toothpastes exist.

Remineralizers.

Hydroxyapatite nanocrystals and a variety of calcium phosphates are included in formulations for remineralization, i.e. the reformation of enamel.

Miscellaneous components.

Agents are added to suppress the tendency of toothpaste to dry into a powder. Included are various sugar alcohols, such as glycerol, sorbitol, or xylitol, or related derivatives, such as 1,2-propylene glycol and polyethyleneglycol. Strontium chloride or potassium nitrate is included in some toothpastes to reduce sensitivity. Two systemic meta-analysis reviews reported that arginine, and calcium sodium phosphosilicate - CSPS containing toothpastes are also effective in alleviating dentinal hypersensitivity respectively. Another randomized clinical trial found superior effects when both formulas were combined together.  Sodium polyphosphate is added to minimize the formation of tartar. Other example to components in toothpastes is the Biotene, which has proved its efficiency in relieving the symptoms of dry mouth in people who suffer from xerostomia according to the results of two randomized clinical trials.  Chlorohexidine mouthwash has been popular for its positive effect on controlling plaque and gingivitis, however, a systemic review studied the effects of chlorohexidine toothpastes and found insufficient evidence to support its use, tooth surface discoloration was observed as a side effect upon using it, which is considered a negative side effect that can affect patients' compliance.  Sodium hydroxide, also known as lye or caustic soda, is listed as an inactive ingredient in some toothpaste, for example Colgate Total.

Xylitol.

Some studies have demonstrated that toothpastes with xylitol as an ingredient are more effective at preventing dental caries in permanent teeth of children than toothpastes containing fluoride alone. Furthermore, xylitol has not been found to cause any harmful effects. Further investigation into the efficacy of toothpastes containing this product is however required as the currently available studies are of low quality and therefore the results of such studies must be applied carefully.

Safety.

Fluoride.

Fluoride-containing toothpaste can be acutely toxic if swallowed in large amounts, but instances are exceedingly rare and result from prolonged and excessive use of toothpaste (i.e. several tubes per week). Approximately 15 mg/kg body weight is the acute lethal dose, even though as small amount as 5 mg/kg may be fatal to some children.  The risk of using fluoride is low enough that the use of full-strength toothpaste (1350–1500 ppm fluoride) is advised for all ages. However, smaller volumes are used for young children, for example, a smear of toothpaste until three years old. A major concern of dental fluorosis is for children under 12 months ingesting excessive fluoride through toothpaste. Nausea and vomiting are also problems which might arise with topical fluoride ingestion.

Diethylene glycol.

The inclusion of sweet-tasting but toxic diethylene glycol in Chinese-made toothpaste led to a recall in 2007 involving multiple toothpaste brands in several nations. The world outcry made Chinese officials ban the practice of using diethylene glycol in toothpaste.

Triclosan.

Reports have suggested triclosan, an active ingredient in many kinds of toothpastes, can combine with chlorine in tap water to form chloroform, which the United States Environmental Protection Agency classifies as a probable human carcinogen. An animal study revealed the chemical might modify hormone regulation, and many other lab researches proved bacteria might be able to develop resistance to triclosan in a way which can help them to resist antibiotics also.

Polyethylene glycol - PEG.

PEG is a common ingredient in some of the formulas of toothpastes; it is a hydrophilic polymer that acts as a dispersant in toothpastes. Also, it is used in many cosmetic and pharmaceutical formulas, for example: ointments, osmotic laxatives, some of the non steroidal anti-inflammatory drugs, other medications and household products. However, 37 cases of PEG hypersensitivity (delayed and immediate) to PEG-containing substances have been reported since 1977, suggesting that they have unrecognized allergenic potential.

Miscellaneous issues and debates.

With the exception of toothpaste intended to be used on pets such as dogs and cats, and toothpaste used by astronauts, most toothpaste is not intended to be swallowed, and doing so may cause nausea or diarrhea. Tartar fighting toothpastes have been debated. Case reports of plasma cell gingivitis have been reported with the use of herbal toothpaste containing cinnamon. Sodium lauryl sulfate (SLS) has been proposed to increase the frequency of mouth ulcers in some people, as it can dry out the protective layer of oral tissues, causing the underlying tissues to become damaged. In studies conducted by the university of Oslo on recurrent aphthous ulcers, it was found that SLS has a denaturing effect on the oral mucin layer, with high affinity for proteins, thereby increasing epithelial permeability. In a double-blind cross-over study, a significantly higher frequency of aphthous ulcers was demonstrated when patients brushed with an SLS-containing versus a detergent-free toothpaste. Also patients with Oral Lichen Planus who avoided SLS-containing toothpaste benefited.

Alteration of taste perception.

After using toothpaste, orange juice and other juices have an unpleasant taste. Sodium lauryl sulfate alters taste perception. It can break down phospholipids that inhibit taste receptors for sweetness, giving food a bitter taste. In contrast, apples are known to taste more pleasant after using toothpaste. Distinguishing between the hypotheses that the bitter taste of orange juice results from stannous fluoride or from sodium lauryl sulfate is still an unresolved issue and it is thought that the menthol added for flavor may also take part in the alteration of taste perception when binding to lingual cold receptors.

Whitening toothpastes.

Many toothpastes make whitening claims. Some of these toothpastes contain peroxide, the same ingredient found in tooth bleaching gels. The abrasive in these toothpastes, not the peroxide, removes the stains. Whitening toothpaste cannot alter the natural color of teeth or reverse discoloration by penetrating surface stains or decay. To remove surface stains, whitening toothpaste may include abrasives to gently polish the teeth or additives such as sodium tripolyphosphate to break down or dissolve stains. When used twice a day, whitening toothpaste typically takes two to four weeks to make teeth appear whiter. Whitening toothpaste is generally safe for daily use, but excessive use might damage tooth enamel. Teeth whitening gels represent an alternative. A recent systematic review in 2017 concluded that nearly all dentifrices that are specifically formulated for tooth whitening were shown to have a beneficial effect in reducing extrinsic stains, irrespective of whether or not a chemical discoloration agent was added. However, the whitening process can permanently reduce the strength of the teeth, as the process scrapes away a protective outer layer of enamel.

Herbal and natural toothpastes.

Companies such as Tom's of Maine, among others, manufacture natural and herbal toothpastes and market them to consumers who wish to avoid the artificial ingredients commonly found in regular toothpastes. Many herbal toothpastes do not contain fluoride or sodium lauryl sulfate. The ingredients found in natural toothpastes vary widely but often include baking soda, aloe, eucalyptus oil, myrrh, plant extract (strawberry extract), and essential oils. A systemic review in 2014 found insufficient evidence to determine whether the aloe vera herbal dentifrice can reduce plaque or improve gingival health, as the randomized studies were found to be flawed with high risk of bias.  According to a study by the Delhi Institute of Pharmaceutical Sciences and Research, many of the herbal toothpastes being sold in India were adulterated with nicotine.  Charcoal has also been incorporated in toothpaste formulas; however, there is no evidence to determine its safety and effectiveness.

Striped toothpaste.

Striped toothpaste was invented by Leonard Marraffino in 1955. The patent (US patent, issued 1957) was subsequently sold to Unilever, who marketed the novelty under the Stripe brand-name in the early 1960s. This was followed by the introduction of the Signal brand in Europe in 1965 (UK patent 813,514). Although Stripe was initially very successful, it never again achieved the 8% market share that it cornered during its second year.  Marraffino's design, which remains in use for single-color stripes, is simple. The main material, usually white, sits at the crimp end of the toothpaste tube and makes up most of its bulk. A thin pipe, through which that carrier material will flow, descends from the nozzle to it. The stripe-material (this was red in Stripe) fills the gap between the carrier material and the top of the tube. The two materials are not in separate compartments, however, they are sufficiently viscous that they will not mix. When pressure is applied to the toothpaste tube, the main material squeezes down the thin pipe to the nozzle. Simultaneously, the pressure applied to the main material causes pressure to be forwarded to the stripe material, which thereby issues out through small holes (in the side of the pipe) onto the main carrier material as it is passing those holes.  In 1990, Colgate-Palmolive was granted a patent (USPTO ) for two differently colored stripes. In this scheme, the inner pipe has a cone-shaped plastic guard around it, and about halfway up its length. Between the guard and the nozzle-end of the tube is a space for the material for one color, which issues out of holes in the pipe. On the other side of the guard is space for second stripe-material, which has its own set of holes.  Striped toothpaste should not be confused with layered toothpaste. Layered toothpaste requires a multi-chamber design (e.g. USPTO ), in which two or three layers extrude out of the nozzle. This scheme, like that of pump dispensers (USPTO ), is more complicated (and thus, more expensive to manufacture) than either the Marraffino design or the Colgate design.

History.

Early toothpastes.

Since 5000 BC, the Egyptians made a tooth powder, which consisted of powdered ashes of ox hooves, myrrh, powdered and burnt eggshells, and pumice. The Greeks, and then the Romans, improved the recipes by adding abrasives such as crushed bones and oyster shells. In the 9th century, Iraqi musician and fashion designer Ziryab invented a type of toothpaste, which he popularized throughout Islamic Spain. The exact ingredients of this toothpaste are unknown, but it was reported to have been both "functional and pleasant to taste". It is not known whether these early toothpastes were used alone, were to be rubbed onto the teeth with rags, or were to be used with early toothbrushes, such as neem-tree twigs and "miswak". During Japan's Edo period, inventor Hiraga Gennai's "Hika rakuyo" (1769), contained advertisements for "Sosekiko", a "toothpaste in a box." Toothpastes or powders came into general use in the 19th century.

Tooth powder.

Tooth powders for use with toothbrushes came into general use in the 19th century in Britain. Most were homemade, with chalk, pulverized brick, or salt as ingredients. An 1866 Home Encyclopedia recommended pulverized charcoal, and cautioned that many patented tooth powders that were commercially marketed did more harm than good.  Arm & Hammer marketed a baking soda-based toothpowder in the United States until approximately 2000, and Colgate currently markets toothpowder in India and other countries.

Modern toothpaste.

An 18th-century American and British toothpaste recipe called for burned bread. Another formula around this time called for dragon's blood (a resin), cinnamon, and burned alum.  By 1900, a paste made of hydrogen peroxide and baking soda was recommended for use with toothbrushes. Pre-mixed toothpastes were first marketed in the 19th century, but did not surpass the popularity of tooth-powder until World War I.  Together with Willoughby D. Miller, Newell Sill Jenkins developed a toothpaste and named it Kolynos, the first toothpaste containing disinfectants. The name's origin is from Greek "Kolyo nosos" (κωλύω νόσος), meaning "disease prevention". Numerous attempts to produce the toothpaste by pharmacists in Europe have been uneconomic. After returning to the US, he continued experimenting with Harry Ward Foote (1875-1942), professor of chemistry at Sheffield Chemical Laboratory of Yale University. After 17 years of development of Kolynos and clinical trials, Jenkins retired and transferred the production and distribution to his son Leonard A. Jenkins, who brought the first toothpaste tubes on the market on April 13, 1908. Within a few years the company expanded in North America, Latin America, Europe and the Far East. A branch operation opened in London in 1909. In 1937, Kolynos was produced in 22 countries and sold in 88 countries. Kolynos has been sold mainly in South America and in Hungary. Colgate-Palmolive took over the production of American Home Products in 1995 at a cost of one billion US dollars.  Fluoride was first added to toothpastes in the 1890s. Tanagra, containing calcium fluoride as the active ingredient, was sold by Karl F. Toellner Company, of Bremen, Germany, based upon the early work of chemist Albert Deninger. An analogous invention by Roy Cross, of Kansas City, Missouri, was initially criticized by the American Dental Association (ADA) in 1937. Fluoride toothpastes developed in the 1950s received the ADA's approval. To develop the first ADA-approved fluoride toothpaste, Procter & Gamble started a research program in the early 1940s. In 1950, Procter & Gamble developed a joint research project team headed by Joseph C. Muhler at Indiana University to study new toothpaste with fluoride. In 1955, Procter & Gamble's Crest launched its first clinically proven fluoride-containing toothpaste. On August 1, 1960, the ADA reported that "Crest has been shown to be an effective anticavity (decay preventative) dentifrice that can be of significant value when used in a conscientiously applied program of oral hygiene and regular professional care."  In 1980, the Japanese company, Sangi Co., Ltd., launched APADENT, the world's first remineralizing toothpaste to use a nano-form of hydroxyapatite, the main component of tooth enamel, rather than fluoride, to remineralize areas of mineral loss below the surface of tooth enamel (incipient caries lesions). After many years of laboratory experiments and field trials, its hydroxyapatite ingredient was approved as an active anti-caries agent by the Japanese Ministry of Health in 1993, and given the name Medical Hydroxyapatite to distinguish it from other forms of hydroxyapatite used in toothpaste, such as dental abrasives.  In 2006, BioRepair appeared in Europe with the first European toothpaste containing synthetic hydroxylapatite as an alternative to fluoride for the remineralization and reparation of tooth enamel. The "biomimetic hydroxylapatite" is intended to protect the teeth by creating a new layer of synthetic enamel around the tooth instead of hardening the existing layer with fluoride that chemically changes it into fluorapatite.

Toothpaste tubes.

In 1880, Doctor Washington Sheffield of New London, CT manufactured toothpaste into a collapsible tube, Dr. Sheffield's Creme Dentifrice. He had the idea after his son traveled to Paris and saw painters using paint from tubes. In York in 1896, Colgate & Company Dental Cream was packaged in collapsible tubes imitating Sheffield. The original collapsible toothpaste tubes were made of lead.

Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, assists in suppressing halitosis, and delivers active ingredients (most commonly fluoride) to help prevent tooth decay (dental caries) and gum disease (gingivitis). Salt and sodium bicarbonate (baking soda) are among materials that can be substituted for commercial toothpaste. Large amounts of swallowed toothpaste can be toxic.

牙膏是一种洁齿剂,一般呈凝胶状,通常会抹在牙刷上用于清洁牙齿保持牙齿美观和亮白。牙膏是用来提高口腔健康问题的:它提供了充足的摩擦力,协助清洁牙齿、牙龈间的牙菌斑、食物等,协助降低口臭问题,其活性成分(一般是氟化物)可防龋以及牙龈相关疾病(牙龈病)。


Overview.

Pedipalps are composed of six segments or articles: the coxae, a single trochanter, the femur, a short patella, the tibia, and the tarsus. In spiders the coxae frequently have extensions called maxillae or gnathobases, which function as mouth parts with or without some contribution from the coxae of the anterior legs. The limbs themselves may be simple tactile organs outwardly resembling the legs, as in spiders, or chelate weapons (pincers) of great size, as in the scorpions.  Comparative studies of pedipalpal morphology may suggest that leg-like pedipalps are primitive in arachnids. At present, the only reasonable alternative to this view is to assume that Xiphosurans reflect the morphology of the primitive arachnid pedipalp and to conclude that this appendage is primitively chelate. Pedipalps are traditionally thought to be homologous with mandibles in crustaceans and insects, although more recent studies (e.g. using Hox genes) suggest they are probably homologous with the crustacean second antennae.

Chelate pedipalps.

Chelate or sub-chelate (pincer-like) pedipalps are found in several arachnid groups (Ricinulei, Thelyphonida, scorpions and pseudoscorpions) but the chelae in most of these groups may not be homologous with those found in Xiphosura. The pedipalps are distinctly raptorial (i.e., modified for seizing prey) in the Amblypygi, Thelyphonida, Schizomida, and some Opiliones belonging to the laniatorid group.

Spider pedipalps.

Pedipalps of spiders have the same segmentation as the legs, but the tarsus is undivided, and the pretarsus has no lateral claws. Pedipalps contain sensitive chemical detectors and function as taste and smell organs, supplementing those on the legs. In sexually mature male spiders, the final segment of the pedipalp, the tarsus, develops a complicated structure (sometimes called the palpal bulb or palpal organ) that is used to transfer sperm to the female seminal receptacles during mating. The details of this structure vary considerably between different groups of spiders and are useful for identifying species.  The cymbium is a spoon-shaped structure located at the end of the spider pedipalp that supports the palpal organ. The cymbium may also be used as a stridulatory organ in spider courtship.  The embolus is a narrow whip-like or leaf-like extension of the palpal bulb.

Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ("jaws") and anterior to the first pair of walking legs.

触肢(英文:Pedipalps),又称为钳足、须肢、颚肢,为螯肢亚门成员(包含蜘蛛、蝎子、鲎与海蜘蛛等在内的一群节肢动物)的第二对附肢,位于螯肢之后,第一对步足之前。


History.

Early years.

The National Hockey League was established in 1917 as the successor to the National Hockey Association (NHA). Founded in 1909, the NHA began play one year later with seven teams in Ontario and Quebec, and was one of the first major leagues in professional ice hockey. But by the NHA's eighth season, a series of disputes with Toronto Blueshirts owner Eddie Livingstone led team owners of the Montreal Canadiens, Montreal Wanderers, Ottawa Senators, and Quebec Bulldogs to hold a meeting to discuss the league's future. Realizing the NHA constitution left them unable to force Livingstone out, the four teams voted instead to suspend the NHA, and on November 26, 1917, formed the National Hockey League. Frank Calder was chosen as its first president, serving until his death in 1943.  The Bulldogs were unable to play, and the remaining owners created a new team in Toronto, the Arenas, to compete with the Canadiens, Wanderers and Senators. The first games were played on December 19, 1917. The Montreal Arena burned down in January 1918, causing the Wanderers to cease operations, and the NHL continued on as a three-team league until the Bulldogs returned

The Original Six.

The first NHL All-Star Game was held in 1934 to benefit Ace Bailey, whose career ended on a vicious hit by Eddie Shore. The second was held in 1937 in support of Howie Morenz's family when he died of a coronary embolism after breaking his leg during a game.  The Great Depression and the onset of World War II took a toll on the league. The Pirates became the Philadelphia Quakers in 1930, then folded one year later. The Senators likewise became the St. Louis Eagles in 1934, also lasting only one year. The Maroons did not survive, as they suspended operations in 1938. The Americans were suspended in 1942 due to a lack of available players,

Post-Original Six expansion.

By the mid-1960s, the desire for a network television contract in the U.S., and concerns that the Western Hockey League was planning to declare itself a major league and challenge for the Stanley Cup, spurred the league to undertake its first expansion since the 1920s. The league doubled in size to 12 teams for the 1967–68 season, adding the Los Angeles Kings, Minnesota North Stars, Philadelphia Flyers, Pittsburgh Penguins, California Seals and St. Louis Blues. Canadian fans were outraged that all six teams were placed in the United States,

Labour issues.

There have been four league-wide work stoppages in NHL history, all occurring after 1992. The first was a strike by the National Hockey League Players' Association in April 1992 which lasted for ten days, but the strike was settled quickly and all affected games were rescheduled.  A lockout at the start of the 1994–95 season forced the league to reduce the schedule from 84 games to just 48, with the teams playing only intra-conference games during the reduced season. The resulting collective bargaining agreement (CBA) was set for renegotiation in 1998 and extended to September 15, 2004.  With no new agreement in hand when the contract expired on September 15, 2004, league commissioner Gary Bettman announced a lockout of the players union and closed the league's head office. The league vowed to install what it dubbed "cost certainty" for its teams, but the Players' Association countered that the move was little more than a euphemism for a salary cap, which the union initially said it would not accept. The lockout shut down the league for 310 days, the

Player safety issues.

Player safety has become a major issue, with concussions – a result from a hard hit to the head – being the primary concern. Recent studies have shown how the consequences of concussions can last beyond player retirement. This has significant effects on the league as elite players have suffered from the aftereffects of concussions, such as Sidney Crosby being sidelined for approximately 10 and a half months, which adversely affects the league's marketability. In December 2009, Brendan Shanahan was hired to replace Colin Campbell and given

Women in the NHL.

From 1952 to 1955, Marguerite Norris served as president of the Detroit Red Wings, the first woman NHL executive and the first woman to have her name engraved on the Stanley Cup. In 1992, Manon Rheaume became the first woman to play a game in any of the major professional North American sports leagues, as a goaltender for the Tampa Bay Lightning in an NHL pre-season game against the St. Louis Blues, stopping seven of nine shots. In 2016, Dawn Braid was hired as the Arizona Coyotes' skating coach, making her the first female full-time coach in

Organizational structure.

Board of Governors.

The Board of Governors is the ruling and governing body of the National Hockey League. In this context, each team is a member of the league, and each member appoints a Governor (usually the owner of the club), and two alternates to the Board.

Executives.

The chief executive of the league is Commissioner Gary Bettman.

Teams.

The NHL consists of 31 teams, 24 of which are based in the United States and seven in Canada. The NHL divides the 31 teams into two conferences: the Eastern Conference and the Western Conference. Each conference is split into two divisions: the Eastern Conference contains 16 teams (eight per division), while the Western Conference has 15 teams (seven in the Central Division and eight in the Pacific Division). The current alignment has existed since the 2017–18 season.  The number of NHL teams held constant at 30 teams from the 2000–01 season when the Minnesota Wild and the Columbus Blue Jackets joined the league as expansion teams, until 2017. That expansion capped a period in the 1990s of rapid expansion and relocation when the NHL added nine

Game.

Each National Hockey League regulation game is 60 minutes long. The game is composed of three 20-minute periods with an intermission between periods. At the end of regulation time, the team with the most goals wins the game. If a game is tied after regulation time, overtime ensues. During the regular season, overtime is a five-minute, three-on-three sudden-death period, in which whoever scores a goal first will win the game. If the game is still tied at the end of overtime, the game enters a shootout. Three players for each team in

Hockey rink.

National Hockey League games are played on a rectangular hockey rink with rounded corners surrounded by walls and Plexiglas. It measures by in the NHL, approximately the same length but much narrower than International Ice Hockey Federation standards. The centre line divides the ice in half, and is used to judge icing violations. There are two blue lines that divide the rink roughly into thirds, delineating one neutral and two attacking zones. Near the end of

Rules.

The National Hockey League's rules are one of the two standard sets of professional ice hockey rules in the world. The rules themselves have evolved directly from the first organized indoor ice hockey game in Montreal in 1875, updated by subsequent leagues up to 1917, when the NHL adopted the existing NHA set of rules. The NHL's rules are the basis for rules governing most professional and major junior ice hockey leagues in North America. Infractions of the rules, such as offside and icing, lead to a stoppage of play and subsequent face-offs, while more serious infractions leading to penalties to the offending teams. The league also determines the specifications for playing equipment used in its games.  The league has regularly modified its rules to counter perceived imperfections in the game. The penalty shot was adopted from the Pacific Coast Hockey Association to ensure players were not being blocked from opportunities to score. For the 2005–06 season, the league changed some of the rules regarding being offside. First, the league removed the "offside pass" or "two-line pass" rule, which required a stoppage in play if a pass originating from inside a team's defending zone was completed on the offensive side of the centre line, unless the puck crossed the line before the player. Furthermore, the league reinstated the "tag-up offside" which allows an attacking player a chance to get back onside by returning to the neutral zone. The changes

Season structure.

The National Hockey League season is divided into a preseason (September and early October), a regular season (from early October through early to mid April) and a postseason (the Stanley Cup playoffs).  Teams usually hold a summer showcase for prospects in July and participate in prospect tournaments, full games that do not feature any veterans, in September. Full training camps begin in mid-to-late September, including a preseason consisting of six to eight exhibition games. Split squad games, in which parts of a team's regular season roster play separate games on the same day, are occasionally played during the preseason.  During the regular season, clubs play each other in a predefined schedule. In the regular season, each team plays 82 games: 41 games each of home and road. Eastern teams play 28 games in their own geographic division—four against each of their seven other divisional opponents—and 24 games against the eight remaining non-divisional intra-conference opponents—three games against every team in the other division of its conference. Western teams play 26 or

Entry Draft.

The annual NHL Entry Draft consists of a seven-round off-season draft held in late June. Early NHL drafts took place at the Queen Elizabeth (currently Fairmont) Hotel in Montreal. Amateur players from junior, collegiate, or European leagues are eligible to enter the Entry Draft. The selection order is determined by a combination of the standings at the end of the regular season, playoff results, and a draft lottery. The 15 teams that did not qualify for the playoffs are entered in a weighted

Trophies and awards.

Teams.

The most prestigious team award is the Stanley Cup, which is awarded to the league champion at the end of the Stanley Cup playoffs. The team that has the most points in the regular season is awarded the Presidents' Trophy.  The Montreal Canadiens are the most successful franchise in the league. Since the formation of the league in 1917, they have 25 NHL championships (three between 1917 and 1925 when the Stanley Cup was still contested in an interleague competition, twenty-two since 1926 after the Stanley Cup became the NHL's championship trophy). They also lead all teams with 24 Stanley Cup championships (one as an NHA team, twenty-three as an NHL team). Of the four major professional sports leagues in North America, the Montreal Canadiens are surpassed

Players.

There are numerous trophies that are awarded to players based on their statistics during the regular season; they include, among others, the Art Ross Trophy for the league scoring champion (goals and assists), the Maurice "Rocket" Richard Trophy for the goal-scoring leader, and the William M. Jennings Trophy for the goaltender(s) for the team with the fewest goals against them.  The other player trophies are voted on by the Professional Hockey Writers' Association or the team general managers. These individual awards are presented at a formal ceremony held in late June after the playoffs have concluded. The most prestigious individual award is the Hart Memorial Trophy which is awarded annually to the Most Valuable Player; the voting is conducted by members of the Professional Hockey Writers Association to judge the player who is the most valuable to his team during the regular season. The Vezina Trophy is awarded annually to the person deemed the best goaltender as voted on by the general managers of the teams in the NHL. The James Norris Memorial Trophy is awarded annually to the

Origin of players.

In addition to Canadian and American born and trained players, who have historically composed a large majority of NHL rosters, the NHL also draws players from an expanding pool of other nations where organized and professional hockey is played. Since the collapse of the Soviet Bloc, political/ideological restrictions on the movement of hockey players from this region have disappeared, leading to a large influx of players mostly from Czech Republic, Slovakia and Russia into the NHL. Swedes, Finns, and other Western Europeans, who were always free to move to North America, came to the league in greater numbers than before.  Many of the league's top players in recent years have come from these European

Corporate sponsors.

The NHL lists its several official corporate partners into three categories: North American Partners, USA Partners, and Canada Partners. Discover Card is the league's official credit card in the US, while competitor Visa is an official sponsor in Canada. Likewise, Tim Hortons is the league's official coffee and doughnuts chain in Canada, while Dunkin' Donuts is the NHL's sponsor in the US.  Among its North American corporate sponsors, Kraft Heinz sponsors "Kraft Hockeyville", an annual competition in which

Media coverage.

Canada.

Broadcasting rights in Canada have historically included the CBC's "Hockey Night in Canada" ("HNIC"), a Canadian tradition dating to 1952, and even prior to that on radio since the 1920s.  The current national television and digital rightsholder is Rogers Communications, under a 12-year deal valued at C$5.2 billion which began in the 2014–15 season, as the national broadcast and cable television rightsholders. National English-language coverage of the NHL is carried primarily by Rogers' Sportsnet group

United States.

Historically, the NHL has never fared well on American television in comparison to the other American professional leagues. The league's American broadcast partners have been in flux for decades, ranging from such networks as CBS, SportsChannel America, the USA Network, Fox, ABC, and ESPN.  National U.S. television rights are currently held by NBC Sports; its current 10-year, US$2 billion contract, which began in the 2011–12 season, extended and unified rights deals that were first established in the 2005–06 season, when Comcast acquired cable rights to replace ESPN, and NBC acquired broadcast television rights under a revenue-sharing agreement to replace ABC. NBC Sports Network and

NHL Network.

The league co-owns the NHL Network, a television specialty channel devoted to the NHL. Its signature show is "NHL Tonight". The NHL Network also airs live

Out-of-market packages.

The NHL operates two subscription-based services allowing access to live, out-of-market games. NHL Centre Ice in Canada and NHL Center Ice in the United States offer access to out-of-market feeds of games through a cable or satellite television provider.

International.

Outside of Canada and the United States, NHL games are broadcast across Europe, in the Middle East, in Australia, and in the Americas across Mexico, Central America, Dominican Republic, Caribbean, South America and Brazil, among others.

International competitions.

The National Hockey League has occasionally participated in international club competitions. Most of these competitions were arranged by the NHL or NHLPA. The first international club competition was held in 1976, with eight NHL teams playing against the Soviet Championship League's HC CSKA Moscow, and Krylya Sovetov Moscow. Between 1976 and 1991, the NHL, and the Soviet Championship League would hold a number of exhibition games between the two leagues known as the Super Series. No NHL club had played a Russian-based club from the end of the Super Series in 1991 to 2008, when the New York Rangers faced Metallurg Magnitogorsk in the 2008 Victoria Cup.  In addition to the Russian clubs, NHL clubs had participated in a number of international club exhibitions and competitions with various European-based clubs. The first exhibition game to feature an NHL team against a European-based team (aside from clubs based in the former Soviet Union) was in December 1977, when the New York Rangers faced Poldi Kladno of the Czechoslovak First Ice Hockey League. In the 2000s the NHL had organized four NHL Challenge series between NHL, and European clubs. From 2007 to 2011, the NHL organized exhibition games prior to the

Popularity.

The NHL is considered one of the four major professional sports leagues in North America, along with Major League Baseball, the National Football League, and the National Basketball Association. The league is very prominent in Canada, where hockey is the most popular of these four major sports as alongside CFL. Overall, hockey has the smallest total fan base of the four leagues, the smallest revenue from television, and the least sponsorship.  The NHL holds one of the most affluent fan bases. Studies by the Sports Marketing Group conducted from 1998 to 2004 show that the NHL's fan base is much more affluent than that of the PGA Tour. A study done by the Stanford Graduate School of Business in 2004, found that NHL fans in America were the most educated and affluent of the four major leagues. Further it noted that season-ticket sales were more prominent in the NHL than the other three because of the financial ability of the NHL fan to purchase them. According to Reuters in 2010, the largest demographic of NHL fans was highly sought after group males aged 18–34. The NHL estimates that half of its fan base roots for teams in outside markets. Beginning in 2008, the NHL began a shift toward using digital technology to market to fans to capitalize on this.  The debut of the Winter Classic, an outdoor regular season NHL game held on New Year's Day 2008, was a major success for the league. The game has since become an annual staple of the NHL schedule. This, along with the transition to a national "Game of the Week" and an annual "Hockey Day in America" regional coverage, all televised on NBC, has helped increase the NHL's regular season television viewership in the United States. These improvements led NBC and the cable channel Versus to sign a ten-year broadcast deal, paying US$200 million per year for both American cable and broadcast rights; the deal will lead to further increases in television coverage on the NBC channels.  This television contract has boosted viewership metrics for the NHL. The 2010 Stanley Cup playoffs saw the largest audience in the history of the sport "after a regular season that saw record-breaking business success, propelled in large part by the NHL's strategy of engaging fans through big events and robust digital offerings." This success has resulted in a 66 percent rise in NHL advertising and sponsorship revenue. Merchandise sales were up 22 percent and the number of unique visitors on the NHL.com website were up 17 percent during the playoffs after rising 29 percent in the regular season.

The National Hockey League (NHL; ) is a professional ice hockey league in North America, currently comprising 31 teams: 24 in the United States and seven in Canada. The NHL is considered to be the premier professional ice hockey league in the world, and one of the major professional sports leagues in the United States and Canada. The Stanley Cup, the oldest professional sports trophy in North America, is awarded annually to the league playoff champion at the end of each season.

国家冰球联盟(英语:英语:National Hockey League,简称NHL,法语:,简称LNH,其他翻译:北美冰联),是一个由北美冰球队伍所组成的职业运动联盟,也是一个非注册非营利性的联盟。NHL是全世界最高层级的职业冰球比赛,为北美四大职业运动之一。队伍共分成东、西两个大区,每个大区各分为三个分区,每年东西两区的冠军会在联盟总决赛中争夺史坦利杯。联盟于1917年在魁北克蒙特利尔成立,成立之初有五支队伍,在一系列的扩展之后,现在共有31支球队,24支位于美国,7支位于加拿大。传统上,因为联盟的加拿大血统,大多数的球员都为加拿大籍。在NHL积极向美国扩展以及它相较于其他联盟的高标准和东欧铁幕垮台后的现成高水准球员的输出,欧洲球员和美国球员人数有着明显增加的趋势。即便如此,2005-2006球季球员名单中有一半的球员仍是在加拿大出生的。


Origins.

One of humanistic psychology's early sources was the work of Carl Rogers, who was strongly influenced by Otto Rank, who broke with Freud in the mid-1920s. Rogers' focus was to ensure that the developmental processes led to healthier, if not more creative, personality functioning. The term 'actualizing tendency' was also coined by Rogers, and was a concept that eventually led Abraham Maslow to study self-actualization as one of the needs of humans. Rogers and Maslow introduced this positive, humanistic psychology in response to what they viewed as the overly pessimistic view of psychoanalysis.  The other sources of inspiration include the philosophies of existentialism and phenomenology.

Conceptual origins.

The humanistic approach has its roots in phenomenological and existentialist thought (see Kierkegaard, Nietzsche, Heidegger, Merleau-Ponty and Sartre). Eastern philosophy and psychology also play a central role in humanistic psychology, as well as Judeo-Christian philosophies of personalism, as each shares similar concerns about the nature of human existence and consciousness.  For further information on influential figures in personalism, see: Emmanuel Mounier, Gabriel Marcel, Denis de Rougemont, Jacques Maritain, Martin Buber, Emmanuel Levinas, Max Scheler and Karol Wojtyla.  As behaviorism grew out of Ivan Pavlov's work with the conditioned reflex, and laid the foundations for academic psychology in the United States associated with the names of John B. Watson and B. F. Skinner; Abraham Maslow gave behaviorism the name "the second force". Historically "the first force" were psychologists like Sigmund Freud, Alfred Adler, Erik Erikson, Carl Jung, Erich Fromm, Karen Horney, Melanie Klein, Harry Stack Sullivan, and others.  In the late 1930s, psychologists, interested in the uniquely human issues, such as the self, self-actualization, health, hope, love, creativity, nature, being, becoming, individuality, and meaning—that is, a concrete understanding of human existence—included Abraham Maslow, Carl Rogers, and Clark Moustakas, who were interested in founding a professional association dedicated to a psychology focused on these features of human capital demanded by post-industrial society.  The humanistic psychology perspective is summarized by five core principles or "postulates" of humanistic psychology first articulated in an article written by James Bugental in 1964 and adapted by Tom Greening, psychologist and long-time editor of the "Journal of Humanistic Psychology". The five basic principles of humanistic psychology are:  While humanistic psychology is a specific division within the American Psychological Association (Division 32), humanistic psychology is not so much a "discipline" within psychology as a "perspective" on the human condition that informs psychological research and practice.

Practical origins.

WWII created practical pressures on military psychologists, they had more patients to see and care for than time or resources permitted. The origins of group therapy are here. Eric Berne's progression of books shows this transition out of what we might call pragmatic psychology of WW II into his later innovation, Transactional Analysis, one of the most influential forms of humanistic Popular Psychology of the later 1960s-1970.

Orientation to scientific research.

Humanistic psychologists generally do not believe that we will understand human consciousness and behavior through mainstream scientific research. The objection that humanistic psychologists have to traditional research methods is that they are derived from and suited for the physical sciences and not especially appropriate to studying the complexities and nuances of human meaning-making.  However, humanistic psychology has involved scientific research of human behavior since its inception. For example:  A human science view is not opposed to quantitative methods, but, following Edmund Husserl:  Research has remained part of the humanistic psychology agenda, though with more of a holistic than reductionistic focus. Specific humanistic research methods evolved in the decades following the formation of the humanistic psychology movement.

Development of the field.

These preliminary meetings eventually led to other developments, which culminated in the description of humanistic psychology as a recognizable "third force" in psychology (first force: psychoanalysis, second force: behaviorism). Significant developments included the formation of the Association for Humanistic Psychology (AHP) in 1961 and the launch of the "Journal of Humanistic Psychology" (originally "The Phoenix") in 1961.  In November 1964 key figures in the movement gathered at Old Saybrook (CT) for the "first invitational conference on Humanistic psychology". The meeting was a co-operation between the Association for Humanistic Psychology (AHP), which sponsored the conference, the Hazen Foundation, which provided financing, and Wesleyan University, which hosted the meeting. In addition to the founding figures of Humanistic psychology; Abraham Maslow, Rollo May, James Bugental and Carl Rogers, the meeting attracted several academic profiles from the humanistic disciplines, including: Gordon Allport, George Kelly, Clark Moustakas, Gardner Murphy, Henry Murray, Robert White, Charlotte Bühler, Floyd Matson, Jacques Barzun and René Dubos. Robert Knapp was chairman and Henry Murray gave the keynote address.  Among the intentions of the participants was to formulate a new vision for psychology that, in their view, took into consideration a more complete image of the person than the image presented by the current trends of Behaviorism and Freudian psychology. According to Aanstoos, Serlin & Greening the participants took issue with the positivistic trend in mainstream psychology at the time. The conference has been described as a historic event that was important for the academic status of Humanistic psychology and its future aspirations.  Subsequently, graduate programs in Humanistic Psychology at institutions of higher learning grew in number and enrollment. In 1971, humanistic psychology as a field was recognized by the American Psychological Association (APA) and granted its own division (Division 32) within the APA. Division 32 publishes its own academic journal called "The Humanistic Psychologist".  The major theorists considered to have prepared the ground for Humanistic Psychology are Otto Rank, Abraham Maslow, Carl Rogers and Rollo May. Maslow was heavily influenced by Kurt Goldstein during their years together at Brandeis University. Psychoanalytic writers also influenced humanistic psychology. Maslow himself famously acknowledged his "indebtedness to Freud" in "Towards a Psychology of Being" Other psychoanalytic influences include the work of Wilhelm Reich, who discussed an essentially 'good', healthy core self and "Character Analysis" (1933), and Carl Gustav Jung's mythological and archetypal emphasis. Other noteworthy inspirations for, and leaders of the movement include Roberto Assagioli, Gordon Allport, Medard Boss, Martin Buber (close to Jacob L. Moreno), James Bugental, Viktor Frankl, Erich Fromm, Hans-Werner Gessmann, Amedeo Giorgi, Kurt Goldstein, Sidney Jourard, R. D. Laing, Clark Moustakas, Lewis Mumford, Fritz Perls, Anthony Sutich, Thomas Szasz, Kirk J. Schneider, and Ken Wilber. Carl Rogers was trained in psychoanalysis before developing humanistic psychology.

Counseling and therapy.

The aim of humanistic therapy is usually to help the client develop a stronger and healthier sense of self, also called self-actualization. Humanistic therapy attempts to teach clients that they have potential for self-fulfillment. This type of therapy is insight-based, meaning that the therapist attempts to provide the client with insights about their inner conflicts.

Approaches.

Humanistic psychology includes several approaches to counseling and therapy. Among the earliest approaches we find the developmental theory of Abraham Maslow, emphasizing a hierarchy of needs and motivations; the existential psychology of Rollo May acknowledging human choice and the tragic aspects of human existence; and the person-centered or client-centered therapy of Carl Rogers, which is centered on the client's capacity for self-direction and understanding of his or her own development. Client-centered therapy is non-directive; the therapist listens to the client without judgement, allowing the client to come to insights by themselves. The therapist should ensure that all of the client's feelings are being considered and that the therapist has a firm grasp on the concerns of the client while ensuring that there is an air of acceptance and warmth. Client-centered therapist engages in active listening during therapy sessions.  A therapist cannot be completely non-directive; however, a nonjudgmental, accepting environment that provides unconditional positive regard will encourage feelings of acceptance and value.  Existential psychotherapies, an application of humanistic psychology, applies existential philosophy, which emphasizes the idea that humans have the freedom to make sense of their lives. They are free to define themselves and do whatever it is they want to do. This is a type of humanistic therapy that forces the client to explore the meaning of their life, as well as its purpose. There is a conflict between having freedoms and having limitations. Examples of limitations include genetics, culture, and many other factors. Existential therapy involves trying to resolve this conflict.  Another approach to humanistic counseling and therapy is Gestalt therapy, which puts a focus on the here and now, especially as an opportunity to look past any preconceived notions and focus on how the present is affected by the past. Role playing also plays a large role in Gestalt therapy and allows for a true expression of feelings that may not have been shared in other circumstances. In Gestalt therapy, non-verbal cues are an important indicator of how the client may actually be feeling, despite the feelings expressed.  Also part of the range of humanistic psychotherapy are concepts from depth therapy, holistic health, encounter groups, sensitivity training, marital and family therapies, body work, the existential psychotherapy of Medard Boss, and Positive Psychology.  Most recently Compassionate Communication, the rebranding of Nonviolent Communication of Marshall Rosenberg seems to be the leading edge of innovation in this field because it is one of very few psychologies with both a simple and clear model of the human psyche and a simple and clear methodology, suitable for any two persons to address and resolve interpersonal conflict without expert intervention, a first in the field.  George Kelly's humanistic theory is based on Fundamental Postulate, where a person acts on anticipation of future events. Stating that a person's actions are based on expectation of possible events and interpretation from past circumstances.

Empathy and self-help.

Empathy is one of the most important aspects of humanistic therapy. This idea focuses on the therapist's ability to see the world through the eyes of the client. Without this, therapists can be forced to apply an external frame of reference where the therapist is no longer understanding the actions and thoughts of the client as the client would, but strictly as a therapist which defeats the purpose of humanistic therapy. Included in empathizing, unconditional positive regard is one of the key elements of humanistic psychology. Unconditional positive regard refers to the care that the therapist needs to have for the client. This ensures that the therapist does not become the authority figure in the relationship allowing for a more open flow of information as well as a kinder relationship between the two. A therapist practicing humanistic therapy needs to show a willingness to listen and ensure the comfort of the patient where genuine feelings may be shared but are not forced upon someone. Marshall Rosenberg, one of Carl Rogers' students, emphasizes empathy in the relationship in his concept of Nonviolent Communication.  Self-help is also part of humanistic psychology: Sheila Ernst and Lucy Goodison have described using some of the main humanistic approaches in self-help groups. Humanistic Psychology is applicable to self-help because it is oriented towards changing the way a person thinks. One can only improve once they decide to change their ways of thinking about themselves, once they decide to help themselves. Co-counselling, which is an approach based purely on self-help, is regarded as coming from humanistic psychology as well. Humanistic theory has had a strong influence on other forms of popular therapy, including Harvey Jackins' Re-evaluation Counselling and the work of Carl Rogers, including his student Eugene Gendlin; (see Focusing) as well as on the development of the Humanistic Psychodrama by Hans-Werner Gessmann since the 80s.

The ideal self.

The ideal self and real self involve understanding the issues that arise from having an idea of what you wish you were as a person, and having that not match with who you actually are as a person (incongruence). The ideal self is what a person believes should be done, as well as what their core values are. The real self is what is actually played out in life. Through humanistic therapy, an understanding of the present allows clients to add positive experiences to their real self-concept. The goal is to have the two concepts of self become congruent. Rogers believed that only when a therapist was able to be congruent, a real relationship occurs in therapy. It is much easier to trust someone who is willing to share feelings openly, even if it may not be what the client always wants; this allows the therapist to foster a strong relationship.

Non-pathological.

Humanistic psychology tends to look beyond the medical model of psychology in order to open up a non-pathologizing view of the person. This usually implies that the therapist downplays the pathological aspects of a person's life in favour of the healthy aspects. Humanistic psychology tries to be a science of human experience, focusing on the actual lived experience of persons. Therefore, a key ingredient is the actual meeting of therapist and client and the possibilities for dialogue to ensue between them. The role of the therapist is to create an environment where the client can freely express any thoughts or feelings; he does not suggest topics for conversation nor does he guide the conversation in any way. The therapist also does not analyze or interpret the client's behavior or any information the client shares. The role of the therapist is to provide empathy and to listen attentively to the client.

Societal applications.

Social change.

While personal transformation may be the primary focus of most humanistic psychologists, many also investigate pressing social, cultural, and gender issues. In an academic anthology from 2018, British psychologist Richard House and his co-editors wrote, "From its very outset, Humanistic Psychology has engaged fulsomely and fearlessly with the social, cultural and political, in a way that much of mainstream scientific, 'positivistic' psychology has sought to avoid". Some of the earliest writers who were associated with and inspired by psychological humanism explored socio-political topics. For example:  Relevant work was not confined to these pioneer thinkers. In 1978, members of the Association for Humanistic Psychology (AHP) embarked on a three-year effort to explore how the principles of humanistic psychology could be used to further the process of positive social and political change. The effort included a "12-Hour Political Party", held in San Francisco in 1980, where nearly 1,400 attendees discussed presentations by such non-traditional social thinkers as "Ecotopia" author Ernest Callenbach, "Aquarian Conspiracy" author Marilyn Ferguson, "Person/Planet" author Theodore Roszak, and "New Age Politics" author Mark Satin. The emergent perspective was summarized in a manifesto by AHP President George Leonard. It proffered such ideas as moving to a slow-growth or no-growth economy, decentralizing and "deprofessionalizing" society, and teaching social and emotional competencies in order to provide a foundation for more humane public policies and a healthier culture.  There have been many other attempts to articulate humanistic-psychology-oriented approaches to social change. For example, in 1979 psychologist Kenneth Lux and economist Mark A. Lutz called for a new economics based on humanistic psychology rather than utilitarianism. Also in 1979, California state legislator John Vasconcellos published a book calling for the integration of liberal politics and humanistic-psychological insight. From 1979–1983 the New World Alliance, a U.S. political organization based in Washington, D.C., attempted to inject humanistic-psychology ideas into political thinking and processes; sponsors of its newsletter included Vasconcellos and Carl Rogers.  In 1989 Maureen O'Hara, who had worked with both Carl Rogers and Paolo Freire, pointed to a convergence between the two thinkers. According to O'Hara, both focus on developing critical consciousness of situations which oppress and dehumanize. Throughout the 1980s and 1990s, Institute of Noetic Sciences president Willis Harman argued that significant social change cannot occur without significant consciousness change. In the 21st century, humanistic psychologists such as Edmund Bourne, Joanna Macy, and Marshall Rosenberg continued to apply psychological insights to social and political issues.  In addition to its uses in thinking about social change, humanistic psychology is considered to be the main theoretical and methodological source of humanistic social work.

Social work.

After psychotherapy, social work is the most important beneficiary of the humanistic psychology's theory and methodology. These theories have produced a deep reform of the modern social work practice and theory, leading, among others, to the occurrence of a particular theory and methodology: Humanistic Social Work. Most values and principles of the humanistic social work practice, described by Malcolm Payne in his book "Humanistic Social Work: Core Principles in Practice", directly originate from the humanistic psychological theory and humanistic psychotherapy practice, namely creativity in human life and practice, developing self and spirituality, developing security and resilience, accountability, flexibility and complexity in human life and practice.  Also, the representation and approach of the client (as "human" being) and social issue (as "human" issue) in social work is made from the humanistic psychology position. According to Petru Stefaroi, the way humanistic representation and approach of the client and their personality is realized is, in fact, the theoretical-axiological and methodological foundation of humanistic social work.  In setting goals and the intervention activities, in order to solve social/human problems, there prevail critical terms and categories of the humanistic psychology and psychotherapy, such as: self-actualization, human potential, holistic approach, human being, free will, subjectivity, human experience, self-determination/development, spirituality, creativity, positive thinking, client-centered and context-centered approach/intervention, empathy, personal growth, empowerment.

Creativity in corporations.

Humanistic psychology's emphasis on creativity and wholeness created a foundation for new approaches towards human capital in the workplace stressing creativity and the relevance of emotional interactions. Previously the connotations of "creativity" were reserved for and primarily restricted to, working artists. In the 1980s, with increasing numbers of people working in the cognitive-cultural economy, creativity came to be seen as a useful commodity and competitive edge for international brands. This led to corporate creativity training in-service trainings for employees, led pre-eminently by Ned Herrmann at G.E. in the late 1970s.  Concepts of humanistic psychology were embraced in education and social work, peaking in the 1970s-1980s in North America. However, as with the whole language theory, training practices were too superficial in most institutional settings. Though humanistic psychology raised the bar of insight and understanding of the whole person, professionally it is primarily practiced today by individual licensed counselors and therapists. Outside of those fields humanistic psychology provides the foundation for virtually every method of Energy Medicine; but little coherence exists yet in this field to discuss it easily.

Humanistic psychology is a psychological perspective that rose to prominence in the mid-20th century in answer to the limitations of Sigmund Freud's psychoanalytic theory and B. F. Skinner's behaviorism. With its roots running from Socrates through the Renaissance, this approach emphasizes the individual's inherent drive toward self-actualization, the process of realizing and expressing one's own capabilities and creativity.

人本主义心理学兴起于20世纪五、六十年代的美国。由亚伯拉罕·马斯洛创立,以卡尔·罗哲斯为代表,被称为除行为学派和精神分析以外,心理学上的「第三势力」。


Toponymy.

The present name seems to derive from "Oxmal," meaning "three times built." This seems to refer to the site's antiquity and the times it had to rebuild. The etymology is disputed; another possibility is "Uchmal" which means "what is to come, the future." By tradition, this was supposed to be an "invisible city," built in one night by the magic of the dwarf king.

Ancient history.

While much work has been done at the popular tourist destination of Uxmal to consolidate and restore buildings, little in the way of serious archeological excavation and research has been done. The city's dates of occupation are unknown and the estimated population (about 15,000 people) is a rough guess. Most of the city's major construction took place while Uxmal was the capital of a Late Classic Maya state around 850-925 AD. After about 1000 AD, Toltec invaders took over, and most building ceased by 1100 AD.  Maya chronicles say that Uxmal was founded about 500 A.D. by Hun Uitzil Chac Tutul Xiu. For generations Uxmal was ruled over by the Xiu family. It was the most powerful site in western Yucatán, and for a while, in alliance with Chichen Itza, dominated all of the northern Maya area. Sometime after about 1200, no new major construction seems to have been made at Uxmal, possibly related to the fall of Uxmal's ally Chichen Itza and the shift of power in Yucatán to Mayapan. The Xiu moved their capital to Maní, and the population of Uxmal declined.  Uxmal was dominant from 875 to 900 CE. The site appears to have been the capital of a regional state in the Puuc region from 850-950 CE. The Maya dynasty expanded their dominion over their neighbors. This prominence did not last long, as the population dispersed around 1000 CE.  After the Spanish conquest of Yucatán (in which the Xiu allied with the Spanish), early colonial documents suggest that Uxmal was still an inhabited place of some importance into the 1550s. As the Spanish did not build a town here, Uxmal was soon after largely abandoned.  The Mayan story "The Dwarf-Wizard of Uxmal" is set in Uxmal.

Description of the site.

Even before the restoration work, Uxmal was in better condition than many other Maya sites. Much was built with well-cut stones set into a core of concrete not relying on plaster to hold the building together. The Maya architecture here is considered matched only by that of Palenque in elegance and beauty. The Puuc style of Maya architecture predominates. Thanks to its good state of preservation, it is one of the few Maya cities where the casual visitor can get a good idea of how the entire ceremonial center looked in ancient times.  Some of the more noteworthy buildings include:  The structure is featured in one of the best-known tales of Yucatec Maya folklore, "el enano del Uxmal" ("the dwarf of Uxmal"), which is also the basis for the structure's common name. Multiple versions of this tale are recorded. It was popularised after one of these was recounted by John Lloyd Stephens in his influential 1841 book, "Incidents of Travel in Central America, Chiapas, and Yucatan". According to Stephens' version, the pyramid was magically built overnight during a series of challenges issued to a dwarf by the "gobernador" (ruler or king) of Uxmal. The dwarf's mother (a "bruja, or witch) arranged the trial of strength and magic to compete against the king. A number of other temple-pyramids, quadrangles, and other monuments, some of significant size, and in varying states of preservation, are also at Uxmal. These include North Long Building, House of the Birds, House of the Turtles, Grand Pyramid, House of the Doves, and South Temple.  The majority of hieroglyphic inscriptions were on a series of stone stelae unusually grouped together on a single platform. The stelae depict the ancient rulers of the city. They show signs that they were deliberately broken and toppled in antiquity; some were re-erected and repaired. A further suggestion of possible war or battle is found in the remains of a wall which encircled most of the central ceremonial center.  A large raised stone pedestrian causeway links Uxmal with the site of Kabah, some 18 km to the south-east. Archaeological research at the small island site of Uaymil, located to the west on the Gulf coast, suggests that it may have served as a port for Uxmal and provided the site access to the circum-peninsular trade network.

Modern history of the ruins.

The site, located not far from Mérida beside a road to Campeche, has attracted many visitors since the time of Mexico's independence. The first detailed account of the ruins was published by Jean Frederic Waldeck in 1838. John Lloyd Stephens and Frederick Catherwood made two extended visits to Uxmal in the early 1840s, with architect/draftsman Catherwood reportedly making so many plans and drawings that they could be used to construct a duplicate of the ancient city (unfortunately most of the drawings are lost).) Désiré Charnay took a series of photographs of Uxmal in 1860. Some three years later Empress Carlota of Mexico visited Uxmal; in preparation for her visit local authorities had some statues and architectural elements depicting phallic themes removed from the ancient façades.  Sylvanus G. Morley made a map of the site in 1909 which included some previously overlooked buildings. The Mexican government's first project to protect some of the structures from risk of collapse or further decay came in 1927. In 1930 Frans Blom led a Tulane University expedition to the site. They made plaster casts of the façades of the "Nunnery Quadrangle"; using these casts, a replica of the Quadrangle was constructed and displayed at the 1933 World's Fair in Chicago, Illinois. The plaster replicas of the architecture were destroyed following the fair, but some of the plaster casts of Uxmal's monuments are still kept at Tulane's Middle American Research Institute. In 1936 a Mexican government repair and consolidation program was begun under José Erosa Peniche.  Queen Elizabeth II of the United Kingdom visited on 27 February 1975 for the inauguration of the site's sound & light show. When the presentation reached the point where the sound system played the Maya prayer to Chaac (the Maya rain deity), a sudden torrential downpour occurred. Gathered dignitaries included Gaspar Antonio Xiu, a descendant of the Xiu noble Maya lineage.  Three hotels and a small museum have been built within walking distance of the ancient city.

Microbial degradation.

Microbial biofilms have been found degrading stone buildings at Uxmal and Kabah. Phototrophs such as "Xenococcus" are found more often on interior walls. However stone degrading "Gloeocapsa" and "Synechocystis" were also present in large numbers. "Aureobasidium" and "Fusarium" fungi species are present at Chichen Itza and Uxmal. Cyanobacteria were prevalent in the interiors of rooms with low light levels.

Uxmal (Yucatec Maya: "Óoxmáal" ) is an ancient Maya city of the classical period located in present-day Mexico. It is considered one of the most important archaeological sites of Maya culture, along with Palenque, Chichén, and Calakmul in Mexico, Caracol and Xunantunich in Belize, and Tikal in Guatemala. It is located in the Puuc region of the eastern Yucatan Peninsula, and is considered one of the Maya cities most representative of the region's dominant architectural style. It has been designated a UNESCO World Heritage Site in recognition of its significance.

乌斯马尔(Uxmal,犹加敦马雅语: Óoxmáal )是位于墨西哥尤卡坦州的大型玛雅古城遗址。1996年,被联合国教科文组织列入世界文化遗产。乌斯马尔的发音为“Oosh-mahl”,在古玛雅语中意为“建造三次”,但亦有玛雅语专家执有异议。


Overview.

At present, there is no single equation of state that accurately predicts the properties of all substances under all conditions. An example of an equation of state correlates densities of gases and liquids to temperatures and pressures, known as the ideal gas law, which is roughly accurate for weakly polar gases at low pressures and moderate temperatures. This equation becomes increasingly inaccurate at higher pressures and lower temperatures, and fails to predict condensation from a gas to a liquid.  Another common use is in modeling the interior of stars, including neutron stars, dense matter (quark–gluon plasmas) and radiation fields. A related concept is the perfect fluid equation of state used in cosmology.  Equations of state can also describe solids, including the transition of solids from one crystalline state to another.  In a practical context, equations of state are instrumental for PVT calculations in process engineering problems, such as petroleum gas/liquid equilibrium calculations. A successful PVT model based on a fitted equation of state can be helpful to determine the state of the flow regime, the parameters for handling the reservoir fluids, and pipe sizing.  Measurements of equation-of-state parameters, especially at high pressures, can be made using lasers.

Historical.

Boyle's law (1662).

Boyle's Law was perhaps the first expression of an equation of state. In 1662, the Irish physicist and chemist Robert Boyle performed a series of experiments employing a J-shaped glass tube, which was sealed on one end. Mercury was added to the tube, trapping a fixed quantity of air in the short, sealed end of the tube. Then the volume of gas was measured as additional mercury was added to the tube. The pressure of the gas could be determined by the difference between the mercury level in the short end of the tube and that in the long, open end. Through these experiments, Boyle noted that the gas volume varied inversely with the pressure. In mathematical form, this can be stated as:  The above relationship has also been attributed to Edme Mariotte and is sometimes referred to as Mariotte's law. However, Mariotte's work was not published until 1676.

Charles's law or Law of Charles and Gay-Lussac (1787).

In 1787 the French physicist Jacques Charles found that oxygen, nitrogen, hydrogen, carbon dioxide, and air expand to roughly the same extent over the same 80-kelvin interval. Later, in 1802, Joseph Louis Gay-Lussac published results of similar experiments, indicating a linear relationship between volume and temperature:

Dalton's law of partial pressures (1801).

Dalton's Law of partial pressure states that the pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone.  Mathematically, this can be represented for "n" species as:

The ideal gas law (1834).

In 1834, Émile Clapeyron combined Boyle's Law and Charles' law into the first statement of the "ideal gas law". Initially, the law was formulated as "pV" = "R"("T" + 267) (with temperature expressed in degrees Celsius), where "R" is the gas constant. However, later work revealed that the number should actually be closer to 273.2, and then the Celsius scale was defined with 0°C = 273.15K, giving:

Van der Waals equation of state (1873).

In 1873, J. D. van der Waals introduced the first equation of state derived by the assumption of a finite volume occupied by the constituent molecules. His new formula revolutionized the study of equations of state, and was most famously continued via the Redlich–Kwong equation of state and the Soave modification of Redlich-Kwong.

General form of an equation of state.

For a given amount of substance contained in a system, the temperature, volume, and pressure are not independent quantities; they are connected by a relationship of the general form  An equation used to model this relationship is called an equation of state. In the following sections major equations of state are described, and the variables used here are defined as follows. Any consistent set of units may be used, although SI units are preferred. Absolute temperature refers to use of the Kelvin (K) or Rankine (°R) temperature scales, with zero being absolute zero.

Classical ideal gas law.

The classical ideal gas law may be written  In the form shown above, the equation of state is thus  If the calorically perfect gas approximation is used, then the ideal gas law may also be expressed as follows  where formula_19 is the density, formula_20 is the adiabatic index (ratio of specific heats), formula_21 is the internal energy per unit mass (the "specific internal energy"), formula_22 is the specific heat at constant volume, and formula_23 is the specific heat at constant pressure.

Cubic equations of state.

Cubic equations of state are called such because they can be rewritten as a cubic function of V.

Van der Waals equation of state.

The Van der Waals equation of state may be written:  where formula_25 is molar volume. The substance-specific constants formula_26 and formula_27 can be calculated from the critical properties formula_28 and formula_29 (noting that formula_29 is the molar volume at the critical point) as:  Also written as  Proposed in 1873, the van der Waals equation of state was one of the first to perform markedly better than the ideal gas law. In this landmark equation formula_26 is called the attraction parameter and formula_27 the repulsion parameter or the effective molecular volume. While the equation is definitely superior to the ideal gas law and does predict the formation of a liquid phase, the agreement with experimental data is limited for conditions where the liquid forms. While the van der Waals equation is commonly referenced in text-books and papers for historical reasons, it is now obsolete. Other modern equations of only slightly greater complexity are much more accurate.  The van der Waals equation may be considered as the ideal gas law, "improved" due to two independent reasons:  With the reduced state variables, i.e. V=V/V, P=P/P and T=T/T, the reduced form of the Van der Waals equation can be formulated:  The benefit of this form is that for given T and P, the reduced volume of the liquid and gas can be calculated directly using Cardano's method for the reduced cubic form:  For P<1 and T<1, the system is in a state of vapor–liquid equilibrium. The reduced cubic equation of state yields in that case 3 solutions. The largest and the lowest solution are the gas and liquid reduced volume.

Redlich-Kwong equation of state.

Introduced in 1949, the Redlich-Kwong equation of state was a considerable improvement over other equations of the time. It is still of interest primarily due to its relatively simple form. While superior to the van der Waals equation of state, it performs poorly with respect to the liquid phase and thus cannot be used for accurately calculating vapor–liquid equilibria. However, it can be used in conjunction with separate liquid-phase correlations for this purpose.  The Redlich-Kwong equation is adequate for calculation of gas phase properties when the ratio of the pressure to the critical pressure (reduced pressure) is less than about one-half of the ratio of the temperature to the critical temperature (reduced temperature):

Soave modification of Redlich-Kwong.

Where ω is the acentric factor for the species.  This formulation for formula_54 is due to Graboski and Daubert. The original formulation from Soave is:  for hydrogen:  We can also write it in the polynomial form, with:  then we have: where formula_60 is the universal gas constant and Z=PV/(RT) is the compressibility factor.  In 1972 G. Soave replaced the 1/ term of the Redlich-Kwong equation with a function α(T,ω) involving the temperature and the acentric factor (the resulting equation is also known as the Soave-Redlich-Kwong equation of state; SRK EOS). The α function was devised to fit the vapor pressure data of hydrocarbons and the equation does fairly well for these materials.  Note especially that this replacement changes the definition of "a" slightly, as the formula_61 is now to the second power.

Volume translation of Peneloux et al. (1982).

The SRK EOS may be written as  where  where formula_54 and other parts of the SRK EOS is defined in the SRK EOS section.  A downside of the SRK EOS, and other cubic EOS, is that the liquid molar volume is significantly less accurate than the gas molar volume. Peneloux et alios (1982) proposed a simple correction for this by introducing a volume translation  where formula_66 is an additional fluid component parameter that translates the molar volume slightly. On the liquid branch of the EOS, a small change in molar volume corresponds to a large change in pressure. On the gas branch of the EOS, a small change in molar volume corresponds to a much smaller change in pressure than for the liquid branch. Thus, the perturbation of the molar gas volume is small. Unfortunately, there are two versions that occur in science and industry.  In the first version only formula_67 is translated,  In the second version both formula_67 and formula_70 are translated, or the translation of formula_67 is followed by a renaming of the composite parameter. This gives  The c-parameter of a fluid mixture is calculated by  The c-parameter of the individual fluid components in a petroleum gas and oil can be estimated by the correlation  where the Rackett compressibility factor formula_75 can be estimated by  A nice feature with the volume translation method of Peneloux et al. (1982) is that it does not affect the vapor-liquid equilibrium calculations. This method of volume translation can also be applied to other cubic EOSs if the c-parameter correlation is adjusted to match the selected EOS.

Peng–Robinson equation of state.

In polynomial form:  where formula_81 is the acentric factor of the species, formula_60 is the universal gas constant and formula_83 is compressibility factor.  The Peng–Robinson equation of state (PR EOS) was developed in 1976 at The University of Alberta by Ding-Yu Peng and Donald Robinson in order to satisfy the following goals:  For the most part the Peng–Robinson equation exhibits performance similar to the Soave equation, although it is generally superior in predicting the liquid densities of many materials, especially nonpolar ones. The departure functions of the Peng–Robinson equation are given on a separate article.  The analytic values of its characteristic constants are:

Peng–Robinson-Stryjek-Vera equations of state.

PRSV1.

A modification to the attraction term in the Peng–Robinson equation of state published by Stryjek and Vera in 1986 (PRSV) significantly improved the model's accuracy by introducing an adjustable pure component parameter and by modifying the polynomial fit of the acentric factor.  The modification is:  where formula_88 is an adjustable pure component parameter. Stryjek and Vera published pure component parameters for many compounds of industrial interest in their original journal article. At reduced temperatures above 0.7, they recommend to set formula_89 and simply use formula_90. For alcohols and water the value of formula_91 may be used up to the critical temperature and set to zero at higher temperatures.

PRSV2.

A subsequent modification published in 1986 (PRSV2) further improved the model's accuracy by introducing two additional pure component parameters to the previous attraction term modification.  The modification is:  where formula_88, formula_94, and formula_95 are adjustable pure component parameters.  PRSV2 is particularly advantageous for VLE calculations. While PRSV1 does offer an advantage over the Peng–Robinson model for describing thermodynamic behavior, it is still not accurate enough, in general, for phase equilibrium calculations. The highly non-linear behavior of phase-equilibrium calculation methods tends to amplify what would otherwise be acceptably small errors. It is therefore recommended that PRSV2 be used for equilibrium calculations when applying these models to a design. However, once the equilibrium state has been determined, the phase specific thermodynamic values at equilibrium may be determined by one of several simpler models with a reasonable degree of accuracy.  One thing to note is that in the PRSV equation, the parameter fit is done in a particular temperature range which is usually below the critical temperature. Above the critical temperature, the PRSV alpha function tends to diverge and become arbitrarily large instead of tending towards 0. Because of this, alternate equations for alpha should be employed above the critical point. This is especially important for systems containing hydrogen which is often found at temperatures far above its critical point. Several alternate formulations have been proposed. Some well known ones are by Twu et all or by Mathias and Copeman.  Peng,-Robinson-Babalola equation of state: (PRB)  Babalola [ ] modified the Peng–Robinson Equation of state as:  formula_96  The attractive force parameter ‘a’, which was considered to be a constant with respect to pressure in Peng–Robinson EOS as well as in other EOS was modified by Babalola. The modification, in which parameter ‘a’ was treated as a variable with respect to pressure for multi component multi-phase high density reservoir systems was to improve accuracy in the prediction of properties of complex reservoir fluids for PVT modeling. The variation was represented with a linear equation:  a = aP + a  where a and a represent the slope and the intercept respectively of the straight line obtained when values of parameter ‘a’ are plotted against pressure.  This modification increases the accuracy of Peng–Robinson equation of state for heavier fluids particularly at pressure ranges (>30MPa) and eliminates the need for tuning the equation of state before use thereby minimizing the cost of using the EOS in the oil industry.

Elliott, Suresh, Donohue equation of state.

The Elliott, Suresh, and Donohue (ESD) equation of state was proposed in 1990. The equation seeks to correct a shortcoming in the Peng–Robinson EOS in that there was an inaccuracy in the van der Waals repulsive term. The EOS accounts for the effect of the shape of a non-polar molecule and can be extended to polymers with the addition of an extra term (not shown). The EOS itself was developed through modeling computer simulations and should capture the essential physics of the size, shape, and hydrogen bonding.  where:  and  where The characteristic size parameter is related to the shape parameter formula_66 through where  Noting the relationships between Boltzmann's constant and the Universal gas constant, and observing that the number of molecules can be expressed in terms of Avogadro's number and the molar mass, the reduced number density formula_104 can be expressed in terms of the molar volume as  The shape parameter formula_115 appearing in the Attraction term and the term formula_116 are given by  where formula_119 is the depth of the square-well potential and is given by  The model can be extended to associating components and mixtures of nonassociating components. Details are in the paper by J.R. Elliott, Jr. "et al." (1990).

Cubic-Plus-Association.

The Cubic-Plus-Association (CPA) equation of state combines the Soave-Redlich-Kwong equation with an association term from Wertheim theory. The development of the equation began in 1995 as a research project that was funded by Shell, and in 1996 an article was published which presented the CPA equation of state.  In the association term formula_130 is the mole fraction of molecules not bonded at site A.

Non-cubic equations of state.

Dieterici equation of state.

where "a" is associated with the interaction between molecules and "b" takes into account the finite size of the molecules, similar to the Van der Waals equation.  The reduced coordinates are:

Virial equations of state.

Virial equation of state.

Although usually not the most convenient equation of state, the virial equation is important because it can be derived directly from statistical mechanics. This equation is also called the Kamerlingh Onnes equation. If appropriate assumptions are made about the mathematical form of intermolecular forces, theoretical expressions can be developed for each of the coefficients. "A" is the first virial coefficient, which has a constant value of 1 and makes the statement that when volume is large, all fluids behave like ideal gases. The second virial coefficient "B" corresponds to interactions between pairs of molecules, "C" to triplets, and so on. Accuracy can be increased indefinitely by considering higher order terms. The coefficients "B", "C", "D", etc. are functions of temperature only.  One of the most accurate equations of state is that from Benedict-Webb-Rubin-Starling shown next. It was very close to a virial equation of state. If the exponential term in it is expanded to two Taylor terms, a virial equation can be derived:  Note that in this virial equation, the fourth and fifth virial terms are zero. The second virial coefficient is monotonically decreasing as temperature is lowered. The third virial coefficient is monotonically increasing as temperature is lowered.

The BWR equation of state.

where  Values of the various parameters for 15 substances can be found in

Lee-Kesler equation of state.

The Lee-Kesler equation of state is based on the corresponding states principle, and is a modification of the BWR equation of state.

SAFT equations of state.

Statistical associating fluid theory (SAFT) equations of state use statistical mechanical methods (in particular perturbation theory) to describe the interactions between molecules in a system. The idea of a SAFT equation of state was first proposed by Chapman et al. in 1989, but since then many different SAFT equations of state have been proposed. Often SAFT equations represent molecules as collections of spherical particles that interact with one another. One popular SAFT equation represents molecules as chains composed of spherical segments (PC-SAFT). In general, SAFT equations give more accurate results than traditional cubic equations of state, especially for systems containing liquids or solids.

Multiparameter equations of state.

Helmholtz Function form.

Multiparameter equations of state (MEOS) can be used to represent pure fluids with high accuracy, in both the liquid and gaseous states. MEOS's represent the Helmholtz function of the fluid as the sum of ideal gas and residual terms. Both terms are explicit in reduced temperature and reduced density - thus:  where:  The reduced density and temperature are typically, though not always, the critical values for the pure fluid.  Other thermodynamic functions can be derived from the MEOS by using appropriate derivatives of the Helmholtz function; hence, because integration of the MEOS is not required, there are few restrictions as to the functional form of the ideal or residual terms. Typical MEOS use upwards of 50 fluid specific parameters, but are able to represent the fluid's properties with high accuracy. MEOS are available currently for about 50 of the most common industrial fluids including refrigerants. Mixture models also exist.

Other equations of state of interest.

Stiffened equation of state.

When considering water under very high pressures, in situations such as underwater nuclear explosions, sonic shock lithotripsy, and sonoluminescence, the stiffened equation of state is often used:  where formula_139 is the internal energy per unit mass, formula_140 is an empirically determined constant typically taken to be about 6.1, and formula_141 is another constant, representing the molecular attraction between water molecules. The magnitude of the correction is about 2 gigapascals (20,000 atmospheres).  The equation is stated in this form because the speed of sound in water is given by formula_142.  Thus water behaves as though it is an ideal gas that is "already" under about 20,000 atmospheres (2 GPa) pressure, and explains why water is commonly assumed to be incompressible: when the external pressure changes from 1 atmosphere to 2 atmospheres (100 kPa to 200 kPa), the water behaves as an ideal gas would when changing from 20,001 to 20,002 atmospheres (2000.1 MPa to 2000.2 MPa).  This equation mispredicts the specific heat capacity of water but few simple alternatives are available for severely nonisentropic processes such as strong shocks.

Ultrarelativistic equation of state.

An ultrarelativistic fluid has equation of state  where formula_41 is the pressure, formula_145 is the mass density, and formula_146 is the speed of sound.

Ideal Bose equation of state.

The equation of state for an ideal Bose gas is  where α is an exponent specific to the system (e.g. in the absence of a potential field, α = 3/2), "z" is exp("μ"/"kT") where "μ" is the chemical potential, Li is the polylogarithm, ζ is the Riemann zeta function, and "T" is the critical temperature at which a Bose–Einstein condensate begins to form.

Jones–Wilkins–Lee equation of state for explosives (JWL equation).

The equation of state from Jones–Wilkins–Lee is used to describe the detonation products of explosives.  The ratio formula_149 is defined by using formula_150 = density of the explosive (solid part) and formula_151 = density of the detonation products. The parameters formula_152, formula_153, formula_154, formula_155 and formula_156 are given by several references. In addition, the initial density (solid part) formula_157, speed of detonation formula_158, Chapman–Jouguet pressure formula_159 and the chemical energy of the explosive formula_160 are given in such references. These parameters are obtained by fitting the JWL-EOS to experimental results. Typical parameters for some explosives are listed in the table below.

Equations of state for solids and liquids.

Common abbreviations: formula_161

In physics and thermodynamics, an equation of state is a thermodynamic equation relating state variables which describe the state of matter under a given set of physical conditions, such as pressure, volume, temperature (PVT), or internal energy. Equations of state are useful in describing the properties of fluids, mixtures of fluids, solids, and the interior of stars.

在物理学和热力学中,状态方程(英语:Equation of state),也称物态方程,表达了热力学系统中若干个态函数参量之间的关系。特别是在热力学中,状态方程是一个热力学方程,描述了给定物理条件环境下物质的状态,例如其温度、压强、体积和内能。状态方程在描述流体、混合流体、固体甚至是研究恒星内部都十分有用。