title: Fran Tarkenton

text: Tarkenton's tenure with the Vikings spanned thirteen non-consecutive seasons. He played for Minnesota six seasons from 1961 to 1966 when he was traded to the New York Giants for five seasons, and then traded back to Minnesota for his last seven seasons from 1972 to 1978. At the time of his retirement, Tarkenton owned many quarterback records. He was inducted into the Pro Football Hall of Fame in 1986 and the College Football Hall of Fame in 1987.


title: Fran Tarkenton

text: In addition to his football career, Tarkenton served as a commentator on "Monday Night Football" and a co-host of "That's Incredible!". He also founded Tarkenton Software, a computer-program generator company, and he toured the U.S. promoting CASE (computer-aided software engineering) with Albert F. Case Jr. of Nastec Corporation. Tarkenton Software later merged with KnowledgeWare (with Tarkenton as president), until selling the company to Sterling Software in 1994.


title: Fran Tarkenton

text: Fran Tarkenton was born on February 3, 1940, in Richmond, Virginia. His father, Dallas Tarkenton, was a Methodist minister. Tarkenton went to Athens High School in Athens, Georgia, and later attended the University of Georgia, where he was the quarterback on the Bulldog football team and a member of the Sigma Alpha Epsilon fraternity.


title: Fran Tarkenton

text: Under head coach Wally Butts and with Tarkenton as quarterback, Georgia won the Southeastern Conference championship in 1959. Tarkenton was a first-team All-SEC selection in both 1959 and 1960.


title: Fran Tarkenton

text: The expansion Minnesota Vikings selected Tarkenton in the third round (29th overall) of the 1961 NFL Draft, and he was picked in the fifth round of the AFL draft by the Boston Patriots. He signed with the Vikings. Tarkenton, 21, played his first NFL game (and the Vikings' first game) on September 17 against the Chicago Bears, coming off the bench to lead the Vikings to a come-from-behind victory by passing for 250 yards and four touchdown passes and running for another as the Vikings defeated the Bears 37–13. He was the only player in NFL history to pass for four touchdowns in his first NFL game, until the feat was repeated by Marcus Mariota in the Tennessee Titans' 2015 season opener versus the Tampa Bay Buccaneers.


title: Fran Tarkenton

text: He played for the Vikings from 1961 through 1966. His early years with the team were plagued by the trouble expected for a newly created team, with the Vikings winning a total of 10 games combined in their first three seasons, with Tarkenton winning eight of them. He threw 18 touchdowns and 17 interceptions for 1,997 yards in his first season. He rushed for 308 yards on 56 rushes for five touchdowns. The following year, he threw 22 touchdowns and 25 interceptions for 2,595 yards. He rushed for 361 yards on 41 rushes for two touchdowns.


title: Fran Tarkenton

text: Tarkenton was traded to the New York Giants in March 1967 for three draft picks (and a player to be named later), at which time he moved to the suburb of New Rochelle, New York. In the first game of the 1969 season, the Giants played the Vikings. After trailing 23–10 in the fourth quarter, Tarkenton threw two touchdown passes to secure a 24–23 comeback victory over his former team. The 24 points allowed by Minnesota's defense were a season-worst for the unit, one more point than the Vikings allowed in losing Super Bowl IV to the Kansas City Chiefs in January.


title: Fran Tarkenton

text: Tarkenton enjoyed his best season with the Giants in 1970. They overcame an 0–3 start with nine wins in the next ten games and moved into position to win the NFC East division championship in week 14. However, New York was routed 31–3 by the Los Angeles Rams at Yankee Stadium to finish at 9–5, one game behind the division champion Dallas Cowboys and the wild card Detroit Lions. The 1970 season was the closest the Giants came to making the playoffs during a 17-year drought, from 1964 through 1980.


title: Fran Tarkenton

text: On January 27, 1972, Tarkenton was traded back to the Vikings for quarterback Norm Snead, receiver Bob Grim, running back Vince Clements, a first rounder in 1972 (24th overall–Larry Jacobson, defensive lineman) and a second rounder in 1973 (40th overall–Brad Van Pelt, linebacker). Tarkenton led the Vikings to three National Football Conference championships, but the Vikings lost each ensuing Super Bowl. In Tarkenton's first Super Bowl appearance, Minnesota lost to the Miami Dolphins 24–7 in Houston. They lost the second to the Pittsburgh Steelers 16–6 in New Orleans, and in the last Super Bowl Tarkenton played (and Minnesota's last Super Bowl to date), the Vikings lost to the Oakland Raiders 32–14 at the Rose Bowl in Pasadena, California.


title: Fran Tarkenton

text: In his eighteen NFL seasons, Tarkenton completed 3,686 of 6,467 passes for 47,003 yards and 342 touchdowns, with 266 interceptions, all of which were NFL records at the time of his retirement. Tarkenton's 47,003 career passing yards rank him fourteenth all time, while his 342 career passing touchdowns is eleventh all time in NFL history. He also is eighth on the all-time list of regular-season wins by a starting quarterback with 124 regular season victories. He used his impressive scrambling ability to rack up 3,674 rushing yards and 32 touchdowns on 675 carries. During his career, Tarkenton ran for a touchdown in 15 different seasons, an NFL record among quarterbacks. He ranks sixth in career rushing yards among quarterbacks, behind Randall Cunningham, Steve Young, Michael Vick, Cam Newton, and Russell Wilson. He is also one of four NFL quarterbacks ever to rush for at least 300 yards in seven different seasons; the others are Cam Newton, Michael Vick and Tobin Rote. When he retired, Tarkenton held NFL career records in pass attempts, completions, yardage, touchdowns, rushing yards by a quarterback, and wins by a starting quarterback.


title: Fran Tarkenton

text: The Vikings finished the 1975 season with an NFC-best 12–2 record and Tarkenton won the NFL Most Valuable Player Award and the NFL Offensive Player of the Year Award while capturing All-Pro honors in the process. He was also a second-team All-Pro in 1973 and earned All-NFC selections in 1972 and 1976. He was named second-team All-NFC in 1970 and 1974. Tarkenton was selected to play in nine Pro Bowls.


title: Fran Tarkenton

text: Despite not winning a Super Bowl, he won six playoff games, and in 1999 he was ranked #59 on "The Sporting News" list of the 100 Greatest Football Players.


title: Fran Tarkenton

text: Tarkenton was inducted into the Georgia Sports Hall of Fame in 1977, the Pro Football Hall of Fame in 1986, the College Football Hall of Fame in 1987, and the Athens, Georgia Athletic Hall of Fame in 2000.


title: Fran Tarkenton

text: A biography of Tarkenton titled "Better Scramble than Lose" was published in 1969. This followed Tarkenton's 1967 autobiography "No Time for Losing" and preceded by several years his 1977 autobiography "Tarkenton" co-written with Jim Klobuchar. The autobiographies chronicle not only his football career but also his personal evolution from his early football days as a preacher's son. Tarkenton co-wrote with Brock Yates a book in 1971 titled "Broken Patterns: The Education of a Quarterback", a chronicle of the 1970 New York Giants season.


title: Fran Tarkenton

text: In 1986, Tarkenton, with author Herb Resincow, wrote a novel titled "Murder at the Super Bowl", the whodunit story of a football coach killed just before his team is to participate in the championship game.


title: Fran Tarkenton

text: Tarkenton wrote the self-help, motivational books "Playing to Win" in 1984, and "How to Motivate People: The Team Strategy for Success" in 1986. He also wrote the motivational self-help business book titled "What Losing Taught Me About Winning", and "Every Day is Game Day". In 1987, Tarkenton hosted a "Think and Grow Rich" TV infomercial that sold the book with an audio cassette version (the audio cassettes contained an introduction and conclusion by Tarkenton).


title: Fran Tarkenton

text: Mark McCormack helped Tarkenton invest, making him wealthy enough to "retire this week if [he] wanted to", as "New York" magazine wrote in 1971. Tarkenton was a pioneer in computer software, and founder of Tarkenton Software, a program generator company. He toured the United States promoting CASE or "computer-aided software engineering" with Albert F. Case, Jr. of Nastec Corporation, but ultimately merged his software firm with James Martin's KnowledgeWare, of which Tarkenton was president until selling the company to Sterling Software in 1994.


title: Fran Tarkenton

text: In 1999, Tarkenton was fined by federal regulators as part of a securities fraud sweep. According to the "LA Times", "In Tarkenton's case, the Hall of Fame quarterback and 10 other former executives of his computer software and consulting firm, KnowledgeWare Inc., were accused of inflating by millions of dollars the company's earnings in reports for its fiscal year ended June 30, 1994. The former Minnesota Vikings quarterback agreed to pay a $100,000 fine and $54,187 in restitution. He did not admit any wrongdoing".


title: Fran Tarkenton

text: Since then, Tarkenton has been promoting various products and services including Tony Robbins and 1-800-BAR-NONE. He also founded GoSmallBiz, a small-business consulting website. He also operates an annuity marketing firm called Tarkenton Financial.


title: Fran Tarkenton

text: During the 2016 Republican National Convention, Tarkenton gave a speech endorsing Republican presidential nominee Donald Trump.


title: Fran Tarkenton

text: His first marriage was to Anna Elaine Merrell of Decatur, GA. They wed on December 22, 1960, at First Baptist Church in Decatur, Georgia, and divorced in March 1982. They had three children: daughter Angela (born 1964), son Matthew (born 1968), and daughter Melissa (born 1969).


title: Fran Tarkenton

text: Tarkenton married his second wife Linda Sebastian in the mid-1980s. They have one daughter, Hayley Gray Tarkenton (born 1988), a singer-songwriter.


title: Liquid crystal

text: Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals. For example, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many types of LC phases, which can be distinguished by their optical properties (such as textures). The contrasting textures arise due to molecules within one area of material ("domain") being oriented in the same direction but different areas having different orientations. LC materials may not always be in a LC state of matter (just as water may be ice or water vapor).


title: Liquid crystal

text: Thermotropic and lyotropic liquid crystals consist mostly of organic molecules, although a few minerals are also known. Thermotropic LCs exhibit a phase transition into the LC phase as temperature changes. Lyotropic LCs exhibit phase transitions as a function of both temperature and concentration of molecules in a solvent (typically water). Metallotropic LCs are composed of both organic and inorganic molecules; their LC transition additionally depends on the inorganic-organic composition ratio.


title: Liquid crystal

text: Examples of LCs exist both in the natural world and in technological applications. Lyotropic LCs abound in living systems; many proteins and cell membranes are LCs, as well as the tobacco mosaic virus. LCs in the mineral world include solutions of soap and various related detergents, and some clays. Widespread liquid-crystal displays (LCD) use liquid crystals.


title: Liquid crystal

text: In 1888, Austrian botanical physiologist Friedrich Reinitzer, working at the Karl-Ferdinands-Universität, examined the physico-chemical properties of various derivatives of cholesterol which now belong to the class of materials known as cholesteric liquid crystals. Previously, other researchers had observed distinct color effects when cooling cholesterol derivatives just above the freezing point, but had not associated it with a new phenomenon. Reinitzer perceived that color changes in a derivative cholesteryl benzoate were not the most peculiar feature. He found that cholesteryl benzoate does not melt in the same manner as other compounds, but has two melting points. At it melts into a cloudy liquid, and at it melts again and the cloudy liquid becomes clear. The phenomenon is reversible. Seeking help from a physicist, on March 14, 1888, he wrote to Otto Lehmann, at that time a "" in Aachen. They exchanged letters and samples. Lehmann examined the intermediate cloudy fluid, and reported seeing crystallites. Reinitzer's Viennese colleague von Zepharovich also indicated that the intermediate "fluid" was crystalline. The exchange of letters with Lehmann ended on April 24, with many questions unanswered. Reinitzer presented his results, with credits to Lehmann and von Zepharovich, at a meeting of the Vienna Chemical Society on May 3, 1888.


title: Liquid crystal

text: By that time, Reinitzer had discovered and described three important features of cholesteric liquid crystals (the name coined by Otto Lehmann in 1904): the existence of two melting points, the reflection of circularly polarized light, and the ability to rotate the polarization direction of light.


title: Liquid crystal

text: After his accidental discovery, Reinitzer did not pursue studying liquid crystals further. The research was continued by Lehmann, who realized that he had encountered a new phenomenon and was in a position to investigate it: In his postdoctoral years he had acquired expertise in crystallography and microscopy. Lehmann started a systematic study, first of cholesteryl benzoate, and then of related compounds which exhibited the double-melting phenomenon. He was able to make observations in polarized light, and his microscope was equipped with a hot stage (sample holder equipped with a heater) enabling high temperature observations. The intermediate cloudy phase clearly sustained flow, but other features, particularly the signature under a microscope, convinced Lehmann that he was dealing with a solid. By the end of August 1889 he had published his results in the Zeitschrift für Physikalische Chemie.


title: Liquid crystal

text: Lehmann's work was continued and significantly expanded by the German chemist Daniel Vorländer, who from the beginning of the 20th century until he retired in 1935, had synthesized most of the liquid crystals known. However, liquid crystals were not popular among scientists and the material remained a pure scientific curiosity for about 80 years.


title: Liquid crystal

text: After World War II, work on the synthesis of liquid crystals was restarted at university research laboratories in Europe. George William Gray, a prominent researcher of liquid crystals, began investigating these materials in England in the late 1940s. His group synthesized many new materials that exhibited the liquid crystalline state and developed a better understanding of how to design molecules that exhibit the state. His book "Molecular Structure and the Properties of Liquid Crystals" became a guidebook on the subject. One of the first U.S. chemists to study liquid crystals was Glenn H. Brown, starting in 1953 at the University of Cincinnati and later at Kent State University. In 1965, he organized the first international conference on liquid crystals, in Kent, Ohio, with about 100 of the world's top liquid crystal scientists in attendance. This conference marked the beginning of a worldwide effort to perform research in this field, which soon led to the development of practical applications for these unique materials.


title: Liquid crystal

text: Liquid crystal materials became a focus of research in the development of flat panel electronic displays beginning in 1962 at RCA Laboratories. When physical chemist Richard Williams applied an electric field to a thin layer of a nematic liquid crystal at 125 °C, he observed the formation of a regular pattern that he called domains (now known as Williams Domains). This led his colleague George H. Heilmeier to perform research on a liquid crystal-based flat panel display to replace the cathode ray vacuum tube used in televisions. But the para-azoxyanisole that Williams and Heilmeier used exhibits the nematic liquid crystal state only above 116 °C, which made it impractical to use in a commercial display product. A material that could be operated at room temperature was clearly needed.


title: Liquid crystal

text: In 1966, Joel E. Goldmacher and Joseph A. Castellano, research chemists in Heilmeier group at RCA, discovered that mixtures made exclusively of nematic compounds that differed only in the number of carbon atoms in the terminal side chains could yield room-temperature nematic liquid crystals. A ternary mixture of Schiff base compounds resulted in a material that had a nematic range of 22–105 °C. Operation at room temperature enabled the first practical display device to be made. The team then proceeded to prepare numerous mixtures of nematic compounds many of which had much lower melting points. This technique of mixing nematic compounds to obtain wide operating temperature range eventually became the industry standard and is still used to tailor materials to meet specific applications.


title: Liquid crystal

text: In 1969, Hans Kelker succeeded in synthesizing a substance that had a nematic phase at room temperature, N-(4-methoxybenzylidene)-4-butylaniline (MBBA), which is one of the most popular subjects of liquid crystal research. The next step to commercialization of liquid-crystal displays was the synthesis of further chemically stable substances (cyanobiphenyls) with low melting temperatures by George Gray. That work with Ken Harrison and the UK MOD (RRE Malvern), in 1973, led to design of new materials resulting in rapid adoption of small area LCDs within electronic products.


title: Liquid crystal

text: These molecules are rod-shaped, some created in the laboratory and some appearing spontaneously in nature. Since then, two new types of LC molecules have been synthesized: disc-shaped (by Sivaramakrishna Chandrasekhar in India in 1977) and cone or bowl shaped (predicted by Lui Lam in China in 1982 and synthesized in Europe in 1985).


title: Liquid crystal

text: In 1991, when liquid crystal displays were already well established, Pierre-Gilles de Gennes working at the Université Paris-Sud received the Nobel Prize in physics "for discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymers".


title: Liquid crystal

text: A large number of chemical compounds are known to exhibit one or several liquid crystalline phases. Despite significant differences in chemical composition, these molecules have some common features in chemical and physical properties. There are three types of thermotropic liquid crystals: discotic, conic (bowlic), and rod-shaped molecules. Discotics are disc-like molecules consisting of a flat core of adjacent aromatic rings, whereas the core in a conic LC is not flat, but is shaped like a rice bowl (a three-dimensional object). This allows for two dimensional columnar ordering, for both discotic and conic LCs. Rod-shaped molecules have an elongated, anisotropic geometry which allows for preferential alignment along one spatial direction.


title: Liquid crystal

text: An extended, structurally rigid, highly anisotropic shape seems to be the main criterion for liquid crystalline behavior, and as a result many liquid crystalline materials are based on benzene rings.


title: Liquid crystal

text: The various liquid-crystal phases (called mesophases) can be characterized by the type of ordering. One can distinguish positional order (whether molecules are arranged in any sort of ordered lattice) and orientational order (whether molecules are mostly pointing in the same direction), and moreover order can be either short-range (only between molecules close to each other) or long-range (extending to larger, sometimes macroscopic, dimensions). Most thermotropic LCs will have an isotropic phase at high temperature. That is that heating will eventually drive them into a conventional liquid phase characterized by random and isotropic molecular ordering (little to no long-range order), and fluid-like flow behavior. Under other conditions (for instance, lower temperature), a LC might inhabit one or more phases with significant anisotropic orientational structure and short-range orientational order while still having an ability to flow.


title: Liquid crystal

text: The ordering of liquid crystalline phases is extensive on the molecular scale. This order extends up to the entire domain size, which may be on the order of micrometers, but usually does not extend to the macroscopic scale as often occurs in classical crystalline solids. However some techniques, such as the use of boundaries or an applied electric field, can be used to enforce a single ordered domain in a macroscopic liquid crystal sample. The orientational ordering in a liquid crystal might extend along only one dimension, with the material being essentially disordered in the other two directions.


title: Liquid crystal

text: Thermotropic phases are those that occur in a certain temperature range. If the temperature rise is too high, thermal motion will destroy the delicate cooperative ordering of the LC phase, pushing the material into a conventional isotropic liquid phase. At too low temperature, most LC materials will form a conventional crystal. Many thermotropic LCs exhibit a variety of phases as temperature is changed. For instance, on heating a particular type of LC molecule (called mesogen) may exhibit various smectic phases followed by the nematic phase and finally the isotropic phase as temperature is increased. An example of a compound displaying thermotropic LC behavior is para-azoxyanisole.


title: Liquid crystal

text: The simplest liquid crystal phase is the nematic. In a nematic phase, organic molecules lack a crystalline positional order, but do self-align with their long axes roughly parallel. The molecules are free to flow and their center of mass positions are randomly distributed as in a liquid, but their orientation is constrained to form a long-range directional order.


title: Liquid crystal

text: The word "nematic" comes from the Greek (""), which means "thread". This term originates from the disclinations: thread-like topological defects observed in nematic phases.


title: Liquid crystal

text: Nematics also exhibit so-called "hedgehog" topological defects. In two dimensions, there are topological defects with topological charges and . Due to hydrodynamics, the defect moves considerably faster than the defect. When placed close to each other, the defects attract; upon collision, they annihilate.


title: Liquid crystal

text: Most nematic phases are uniaxial: they have one axis (called a directrix) that is longer and preferred, with the other two being equivalent (can be approximated as cylinders or rods). However, some liquid crystals are biaxial nematic, meaning that in addition to orienting their long axis, they also orient along a secondary axis. Nematic crystals have fluidity similar to that of ordinary (isotropic) liquids but they can be easily aligned by an external magnetic or electric field. Aligned nematics have the optical properties of uniaxial crystals and this makes them extremely useful in liquid-crystal displays (LCD).


title: Liquid crystal

text: Nematic phases are also known in non-molecular systems: at high magnetic fields, electrons flow in bundles or stripes to create an "electronic nematic" form of matter.


title: Liquid crystal

text: The smectic phases, which are found at lower temperatures than the nematic, form well-defined layers that can slide over one another in a manner similar to that of soap. The word "smectic" originates from the Latin word "smecticus", meaning cleaning, or having soap-like properties.


title: Liquid crystal

text: The smectics are thus positionally ordered along one direction. In the Smectic A phase, the molecules are oriented along the layer normal, while in the Smectic C phase they are tilted away from it. These phases are liquid-like within the layers. There are many different smectic phases, all characterized by different types and degrees of positional and orientational order. Beyond organic molecules, Smectic ordering has also been reported to occur within colloidal suspensions of 2-D materials or nanosheets. One example of smectic LCs is "p,p"'-dinonylazobenzene.


title: Liquid crystal

text: The chiral nematic phase exhibits chirality (handedness). This phase is often called the "cholesteric" phase because it was first observed for cholesterol derivatives. Only chiral molecules can give rise to such a phase. This phase exhibits a twisting of the molecules perpendicular to the director, with the molecular axis parallel to the director. The finite twist angle between adjacent molecules is due to their asymmetric packing, which results in longer-range chiral order. In the smectic C* phase (an asterisk denotes a chiral phase), the molecules have positional ordering in a layered structure (as in the other smectic phases), with the molecules tilted by a finite angle with respect to the layer normal. The chirality induces a finite azimuthal twist from one layer to the next, producing a spiral twisting of the molecular axis along the layer normal, hence they are also called "twisted nematics".


title: Liquid crystal

text: The "chiral pitch", p, refers to the distance over which the LC molecules undergo a full 360° twist (but note that the structure of the chiral nematic phase repeats itself every half-pitch, since in this phase directors at 0° and ±180° are equivalent). The pitch, p, typically changes when the temperature is altered or when other molecules are added to the LC host (an achiral LC host material will form a chiral phase if doped with a chiral material), allowing the pitch of a given material to be tuned accordingly. In some liquid crystal systems, the pitch is of the same order as the wavelength of visible light. This causes these systems to exhibit unique optical properties, such as Bragg reflection and low-threshold laser emission, and these properties are exploited in a number of optical applications. For the case of Bragg reflection only the lowest-order reflection is allowed if the light is incident along the helical axis, whereas for oblique incidence higher-order reflections become permitted. Cholesteric liquid crystals also exhibit the unique property that they reflect circularly polarized light when it is incident along the helical axis and elliptically polarized if it comes in obliquely.


title: Liquid crystal

text: Blue phases are liquid crystal phases that appear in the temperature range between a chiral nematic phase and an isotropic liquid phase. Blue phases have a regular three-dimensional cubic structure of defects with lattice periods of several hundred nanometers, and thus they exhibit selective Bragg reflections in the wavelength range of visible light corresponding to the cubic lattice. It was theoretically predicted in 1981 that these phases can possess icosahedral symmetry similar to quasicrystals.


title: Liquid crystal

text: Although blue phases are of interest for fast light modulators or tunable photonic crystals, they exist in a very narrow temperature range, usually less than a few kelvins. Recently the stabilization of blue phases over a temperature range of more than 60 K including room temperature (260–326 K) has been demonstrated. Blue phases stabilized at room temperature allow electro-optical switching with response times of the order of 10 s. In May 2008, the first blue phase mode LCD panel had been developed.


title: Liquid crystal

text: Blue phase crystals, being a periodic cubic structure with a bandgap in the visible wavelength range, can be considered as 3D photonic crystals. Producing ideal blue phase crystals in large volumes is still problematic, since the produced crystals are usually polycrystalline (platelet structure) or the single crystal size is limited (in the micrometer range). Recently, blue phases obtained as ideal 3D photonic crystals in large volumes have been stabilized and produced with different controlled crystal lattice orientations.


title: Liquid crystal

text: Disk-shaped LC molecules can orient themselves in a layer-like fashion known as the discotic nematic phase. If the disks pack into stacks, the phase is called a discotic columnar. The columns themselves may be organized into rectangular or hexagonal arrays. Chiral discotic phases, similar to the chiral nematic phase, are also known.


title: Liquid crystal

text: Conic LC molecules, like in discotics, can form columnar phases. Other phases, such as nonpolar nematic, polar nematic, stringbean, donut and onion phases, have been predicted. Conic phases, except nonpolar nematic, are polar phases.


title: Liquid crystal

text: A lyotropic liquid crystal consists of two or more components that exhibit liquid-crystalline properties in certain concentration ranges. In the lyotropic phases, solvent molecules fill the space around the compounds to provide fluidity to the system. In contrast to thermotropic liquid crystals, these lyotropics have another degree of freedom of concentration that enables them to induce a variety of different phases.


title: Liquid crystal

text: A compound that has two immiscible hydrophilic and hydrophobic parts within the same molecule is called an amphiphilic molecule. Many amphiphilic molecules show lyotropic liquid-crystalline phase sequences depending on the volume balances between the hydrophilic part and hydrophobic part. These structures are formed through the micro-phase segregation of two incompatible components on a nanometer scale. Soap is an everyday example of a lyotropic liquid crystal.


title: Liquid crystal

text: The content of water or other solvent molecules changes the self-assembled structures. At very low amphiphile concentration, the molecules will be dispersed randomly without any ordering. At slightly higher (but still low) concentration, amphiphilic molecules will spontaneously assemble into micelles or vesicles. This is done so as to 'hide' the hydrophobic tail of the amphiphile inside the micelle core, exposing a hydrophilic (water-soluble) surface to aqueous solution. These spherical objects do not order themselves in solution, however. At higher concentration, the assemblies will become ordered. A typical phase is a hexagonal columnar phase, where the amphiphiles form long cylinders (again with a hydrophilic surface) that arrange themselves into a roughly hexagonal lattice. This is called the middle soap phase. At still higher concentration, a lamellar phase (neat soap phase) may form, wherein extended sheets of amphiphiles are separated by thin layers of water. For some systems, a cubic (also called viscous isotropic) phase may exist between the hexagonal and lamellar phases, wherein spheres are formed that create a dense cubic lattice. These spheres may also be connected to one another, forming a bicontinuous cubic phase.


title: Liquid crystal

text: The objects created by amphiphiles are usually spherical (as in the case of micelles), but may also be disc-like (bicelles), rod-like, or biaxial (all three micelle axes are distinct). These anisotropic self-assembled nano-structures can then order themselves in much the same way as thermotropic liquid crystals do, forming large-scale versions of all the thermotropic phases (such as a nematic phase of rod-shaped micelles).


title: Liquid crystal

text: For some systems, at high concentrations, inverse phases are observed. That is, one may generate an inverse hexagonal columnar phase (columns of water encapsulated by amphiphiles) or an inverse micellar phase (a bulk liquid crystal sample with spherical water cavities).


title: Liquid crystal

text: Even within the same phases, their self-assembled structures are tunable by the concentration: for example, in lamellar phases, the layer distances increase with the solvent volume. Since lyotropic liquid crystals rely on a subtle balance of intermolecular interactions, it is more difficult to analyze their structures and properties than those of thermotropic liquid crystals.


title: Liquid crystal

text: Liquid crystal phases can also be based on low-melting inorganic phases like ZnCl that have a structure formed of linked tetrahedra and easily form glasses. The addition of long chain soap-like molecules leads to a series of new phases that show a variety of liquid crystalline behavior both as a function of the inorganic-organic composition ratio and of temperature. This class of materials has been named metallotropic.


title: Liquid crystal

text: Thermotropic mesophases are detected and characterized by two major methods, the original method was use of thermal optical microscopy, in which a small sample of the material was placed between two crossed polarizers; the sample was then heated and cooled. As the isotropic phase would not significantly affect the polarization of the light, it would appear very dark, whereas the crystal and liquid crystal phases will both polarize the light in a uniform way, leading to brightness and color gradients. This method allows for the characterization of the particular phase, as the different phases are defined by their particular order, which must be observed. The second method, differential scanning calorimetry (DSC), allows for more precise determination of phase transitions and transition enthalpies. In DSC, a small sample is heated in a way that generates a very precise change in temperature with respect to time. During phase transitions, the heat flow required to maintain this heating or cooling rate will change. These changes can be observed and attributed to various phase transitions, such as key liquid crystal transitions.


title: Liquid crystal

text: Lyotropic mesophases are analyzed in a similar fashion, though these experiments are somewhat more complex, as the concentration of mesogen is a key factor. These experiments are run at various concentrations of mesogen in order to analyze that impact.


title: Liquid crystal

text: Lyotropic liquid-crystalline phases are abundant in living systems, the study of which is referred to as lipid polymorphism. Accordingly, lyotropic liquid crystals attract particular attention in the field of biomimetic chemistry. In particular, biological membranes and cell membranes are a form of liquid crystal. Their constituent molecules (e.g. phospholipids) are perpendicular to the membrane surface, yet the membrane is flexible. These lipids vary in shape (see page on lipid polymorphism). The constituent molecules can inter-mingle easily, but tend not to leave the membrane due to the high energy requirement of this process. Lipid molecules can flip from one side of the membrane to the other, this process being catalyzed by flippases and floppases (depending on the direction of movement). These liquid crystal membrane phases can also host important proteins such as receptors freely "floating" inside, or partly outside, the membrane, e.g. CTP:phosphocholine cytidylyltransferase (CCT).


title: Liquid crystal

text: Many other biological structures exhibit liquid-crystal behavior. For instance, the concentrated protein solution that is extruded by a spider to generate silk is, in fact, a liquid crystal phase. The precise ordering of molecules in silk is critical to its renowned strength. DNA and many polypeptides, including actively-driven cytoskeletal filaments, can also form liquid crystal phases. Monolayers of elongated cells have also been described to exhibit liquid-crystal behavior, and the associated topological defects have been associated with biological consequences, including cell death and extrusion. Together, these biological applications of liquid crystals form an important part of current academic research.


title: Liquid crystal

text: Examples of liquid crystals can also be found in the mineral world, most of them being lyotropic. The first discovered was vanadium(V) oxide, by Zocher in 1925. Since then, few others have been discovered and studied in detail. The existence of a true nematic phase in the case of the smectite clays family was raised by Langmuir in 1938, but remained an open question for a very long time and was only confirmed recently.


title: Liquid crystal

text: With the rapid development of nanosciences, and the synthesis of many new anisotropic nanoparticles, the number of such mineral liquid crystals is increasing quickly, with, for example, carbon nanotubes and graphene. A lamellar phase was even discovered, HSbPO, which exhibits hyperswelling up to ~250 nm for the interlamellar distance.


title: Liquid crystal

text: Anisotropy of liquid crystals is a property not observed in other fluids. This anisotropy makes flows of liquid crystals behave more differentially than those of ordinary fluids. For example, injection of a flux of a liquid crystal between two close parallel plates (viscous fingering) causes orientation of the molecules to couple with the flow, with the resulting emergence of dendritic patterns. This anisotropy is also manifested in the interfacial energy (surface tension) between different liquid crystal phases. This anisotropy determines the equilibrium shape at the coexistence temperature, and is so strong that usually facets appear. When temperature is changed one of the phases grows, forming different morphologies depending on the temperature change. Since growth is controlled by heat diffusion, anisotropy in thermal conductivity favors growth in specific directions, which has also an effect on the final shape.


title: Liquid crystal

text: Microscopic theoretical treatment of fluid phases can become quite complicated, owing to the high material density, meaning that strong interactions, hard-core repulsions, and many-body correlations cannot be ignored. In the case of liquid crystals, anisotropy in all of these interactions further complicates analysis. There are a number of fairly simple theories, however, that can at least predict the general behavior of the phase transitions in liquid crystal systems.


title: Liquid crystal

text: As we already saw above, the nematic liquid crystals are composed of rod-like molecules with the long axes of neighboring molecules aligned approximately to one another. To describe this anisotropic structure, a dimensionless unit vector n called the "director", is introduced to represent the direction of preferred orientation of molecules in the neighborhood of any point. Because there is no physical polarity along the director axis, n and -n are fully equivalent.


title: Liquid crystal

text: The description of liquid crystals involves an analysis of order. A second rank symmetric traceless tensor order parameter formula_1 is used to describe the orientational order of the most general biaxial nematic liquid crystal. However, to describe the more common case of uniaxial nematic liquid crystals, a scalar order parameter is sufficient. To make this quantitative, an orientational order parameter is usually defined based on the average of the second Legendre polynomial:


title: Liquid crystal

text: where formula_3 is the angle between the liquid-crystal molecular axis and the "local director" (which is the 'preferred direction' in a volume element of a liquid crystal sample, also representing its "local optical axis"). The brackets denote both a temporal and spatial average. This definition is convenient, since for a completely random and isotropic sample, "S" = 0, whereas for a perfectly aligned sample S=1. For a typical liquid crystal sample, "S" is on the order of 0.3 to 0.8, and generally decreases as the temperature is raised. In particular, a sharp drop of the order parameter to 0 is observed when the system undergoes a phase transition from an LC phase into the isotropic phase. The order parameter can be measured experimentally in a number of ways; for instance, diamagnetism, birefringence, Raman scattering, NMR and EPR can be used to determine S.


title: Liquid crystal

text: The order of a liquid crystal could also be characterized by using other even Legendre polynomials (all the odd polynomials average to zero since the director can point in either of two antiparallel directions). These higher-order averages are more difficult to measure, but can yield additional information about molecular ordering.


title: Liquid crystal

text: A positional order parameter is also used to describe the ordering of a liquid crystal. It is characterized by the variation of the density of the center of mass of the liquid crystal molecules along a given vector. In the case of positional variation along the "z"-axis the density formula_4 is often given by:


title: Liquid crystal

text: The complex positional order parameter is defined as formula_6 and formula_7 the average density. Typically only the first two terms are kept and higher order terms are ignored since most phases can be described adequately using sinusoidal functions. For a perfect nematic formula_8 and for a smectic phase formula_9 will take on complex values. The complex nature of this order parameter allows for many parallels between nematic to smectic phase transitions and conductor to superconductor transitions.


title: Liquid crystal

text: A simple model which predicts lyotropic phase transitions is the hard-rod model proposed by Lars Onsager. This theory considers the volume excluded from the center-of-mass of one idealized cylinder as it approaches another. Specifically, if the cylinders are oriented parallel to one another, there is very little volume that is excluded from the center-of-mass of the approaching cylinder (it can come quite close to the other cylinder). If, however, the cylinders are at some angle to one another, then there is a large volume surrounding the cylinder which the approaching cylinder's center-of-mass cannot enter (due to the hard-rod repulsion between the two idealized objects). Thus, this angular arrangement sees a "decrease" in the net positional entropy of the approaching cylinder (there are fewer states available to it).


title: Liquid crystal

text: The fundamental insight here is that, whilst parallel arrangements of anisotropic objects lead to a decrease in orientational entropy, there is an increase in positional entropy. Thus in some case greater positional order will be entropically favorable. This theory thus predicts that a solution of rod-shaped objects will undergo a phase transition, at sufficient concentration, into a nematic phase. Although this model is conceptually helpful, its mathematical formulation makes several assumptions that limit its applicability to real systems.


title: Liquid crystal

text: This statistical theory, proposed by Alfred Saupe and Wilhelm Maier, includes contributions from an attractive intermolecular potential from an induced dipole moment between adjacent rod-like liquid crystal molecules. The anisotropic attraction stabilizes parallel alignment of neighboring molecules, and the theory then considers a mean-field average of the interaction. Solved self-consistently, this theory predicts thermotropic nematic-isotropic phase transitions, consistent with experiment. Maier-Saupe mean field theory is extended to high molecular weight liquid crystals by incorporating the bending stiffness of the molecules and using the method of path integrals in polymer science.


title: Liquid crystal

text: McMillan's model, proposed by William McMillan, is an extension of the Maier–Saupe mean field theory used to describe the phase transition of a liquid crystal from a nematic to a smectic A phase. It predicts that the phase transition can be either continuous or discontinuous depending on the strength of the short-range interaction between the molecules. As a result, it allows for a triple critical point where the nematic, isotropic, and smectic A phase meet. Although it predicts the existence of a triple critical point, it does not successfully predict its value. The model utilizes two order parameters that describe the orientational and positional order of the liquid crystal. The first is simply the average of the second Legendre polynomial and the second order parameter is given by:


title: Liquid crystal

text: The values "z, θ", and "d" are the position of the molecule, the angle between the molecular axis and director, and the layer spacing. The postulated potential energy of a single molecule is given by:


title: Liquid crystal

text: Here constant α quantifies the strength of the interaction between adjacent molecules. The potential is then used to derive the thermodynamic properties of the system assuming thermal equilibrium. It results in two self-consistency equations that must be solved numerically, the solutions of which are the three stable phases of the liquid crystal.


title: Liquid crystal

text: In this formalism, a liquid crystal material is treated as a continuum; molecular details are entirely ignored. Rather, this theory considers perturbations to a presumed oriented sample. The distortions of the liquid crystal are commonly described by the Frank free energy density. One can identify three types of distortions that could occur in an oriented sample: (1) twists of the material, where neighboring molecules are forced to be angled with respect to one another, rather than aligned; (2) splay of the material, where bending occurs perpendicular to the director; and (3) bend of the material, where the distortion is parallel to the director and molecular axis. All three of these types of distortions incur an energy penalty. They are distortions that are induced by the boundary conditions at domain walls or the enclosing container. The response of the material can then be decomposed into terms based on the elastic constants corresponding to the three types of distortions. Elastic continuum theory is an effective tool for modeling liquid crystal devices and lipid bilayers.


title: Liquid crystal

text: Scientists and engineers are able to use liquid crystals in a variety of applications because external perturbation can cause significant changes in the macroscopic properties of the liquid crystal system. Both electric and magnetic fields can be used to induce these changes. The magnitude of the fields, as well as the speed at which the molecules align are important characteristics industry deals with. Special surface treatments can be used in liquid crystal devices to force specific orientations of the director.


title: Liquid crystal

text: The ability of the director to align along an external field is caused by the electric nature of the molecules. Permanent electric dipoles result when one end of a molecule has a net positive charge while the other end has a net negative charge. When an external electric field is applied to the liquid crystal, the dipole molecules tend to orient themselves along the direction of the field.


title: Liquid crystal

text: Even if a molecule does not form a permanent dipole, it can still be influenced by an electric field. In some cases, the field produces slight re-arrangement of electrons and protons in molecules such that an induced electric dipole results. While not as strong as permanent dipoles, orientation with the external field still occurs.


title: Liquid crystal

text: where formula_13, formula_14 and formula_15 are the components of the electric field, electric displacement field and polarization density. The electric energy per volume stored in the system is


title: Liquid crystal

text: (summation over the doubly appearing index formula_17). In nematic liquid crystals, the polarization, and electric displacement both depend linearly on the direction of the electric field. The polarization should be even in the director since liquid crystals are invariants under reflexions of formula_18. The most general form to express formula_19 is


title: Liquid crystal

text: (summation over formula_17). If formula_27 is positive, then the minimum of the energy is achieved when formula_28 and formula_18 are parallel. This means that the system will favor aligning the liquid crystal with the externally applied electric field. If formula_27 is negative, then the minimum of the energy is achieved when formula_28 and formula_18 are perpendicular (in nematics the perpendicular orientation is degenerated, making possible the emergence of vortices).


title: Liquid crystal

text: The difference formula_33 is called dielectrical anisotropy and is an important parameter in liquid crystal applications. There are both formula_34 and formula_35 commercial liquid crystals. 5CB and E7 liquid crystal mixture are two formula_34 liquid crystals commonly used. MBBA is a common formula_35 liquid crystal.


title: Liquid crystal

text: The effects of magnetic fields on liquid crystal molecules are analogous to electric fields. Because magnetic fields are generated by moving electric charges, permanent magnetic dipoles are produced by electrons moving about atoms. When a magnetic field is applied, the molecules will tend to align with or against the field. Electromagnetic radiation, e.g. UV-Visible light, can influence light-responsive liquid crystals which mainly carry at least a photo-switchable unit.


title: Liquid crystal

text: In the absence of an external field, the director of a liquid crystal is free to point in any direction. It is possible, however, to force the director to point in a specific direction by introducing an outside agent to the system. For example, when a thin polymer coating (usually a polyimide) is spread on a glass substrate and rubbed in a single direction with a cloth, it is observed that liquid crystal molecules in contact with that surface align with the rubbing direction. The currently accepted mechanism for this is believed to be an epitaxial growth of the liquid crystal layers on the partially aligned polymer chains in the near surface layers of the polyimide.


title: Liquid crystal

text: Several liquid crystal chemicals also align to a 'command surface' which is in turn aligned by electric field of polarized light. This process is called photoalignment.


title: Liquid crystal

text: The competition between orientation produced by surface anchoring and by electric field effects is often exploited in liquid crystal devices. Consider the case in which liquid crystal molecules are aligned parallel to the surface and an electric field is applied perpendicular to the cell. At first, as the electric field increases in magnitude, no change in alignment occurs. However at a threshold magnitude of electric field, deformation occurs. Deformation occurs where the director changes its orientation from one molecule to the next. The occurrence of such a change from an aligned to a deformed state is called a Fredericks transition and can also be produced by the application of a magnetic field of sufficient strength.


title: Liquid crystal

text: The Fredericks transition is fundamental to the operation of many liquid crystal displays because the director orientation (and thus the properties) can be controlled easily by the application of a field.


title: Liquid crystal

text: As already described, chiral liquid-crystal molecules usually give rise to chiral mesophases. This means that the molecule must possess some form of asymmetry, usually a stereogenic center. An additional requirement is that the system not be racemic: a mixture of right- and left-handed molecules will cancel the chiral effect. Due to the cooperative nature of liquid crystal ordering, however, a small amount of chiral dopant in an otherwise achiral mesophase is often enough to select out one domain handedness, making the system overall chiral.


title: Liquid crystal

text: Chiral phases usually have a helical twisting of the molecules. If the pitch of this twist is on the order of the wavelength of visible light, then interesting optical interference effects can be observed. The chiral twisting that occurs in chiral LC phases also makes the system respond differently from right- and left-handed circularly polarized light. These materials can thus be used as polarization filters.


title: Liquid crystal

text: It is possible for chiral LC molecules to produce essentially achiral mesophases. For instance, in certain ranges of concentration and molecular weight, DNA will form an achiral line hexatic phase. An interesting recent observation is of the formation of chiral mesophases from achiral LC molecules. Specifically, bent-core molecules (sometimes called banana liquid crystals) have been shown to form liquid crystal phases that are chiral. In any particular sample, various domains will have opposite handedness, but within any given domain, strong chiral ordering will be present. The appearance mechanism of this macroscopic chirality is not yet entirely clear. It appears that the molecules stack in layers and orient themselves in a tilted fashion inside the layers. These liquid crystals phases may be ferroelectric or anti-ferroelectric, both of which are of interest for applications.


title: Liquid crystal

text: Chirality can also be incorporated into a phase by adding a chiral dopant, which may not form LCs itself. Twisted-nematic or super-twisted nematic mixtures often contain a small amount of such dopants.


title: Liquid crystal

text: Liquid crystals find wide use in liquid crystal displays, which rely on the optical properties of certain liquid crystalline substances in the presence or absence of an electric field. In a typical device, a liquid crystal layer (typically 4 μm thick) sits between two polarizers that are crossed (oriented at 90° to one another). The liquid crystal alignment is chosen so that its relaxed phase is a twisted one (see Twisted nematic field effect). This twisted phase reorients light that has passed through the first polarizer, allowing its transmission through the second polarizer (and reflected back to the observer if a reflector is provided). The device thus appears transparent. When an electric field is applied to the LC layer, the long molecular axes tend to align parallel to the electric field thus gradually untwisting in the center of the liquid crystal layer. In this state, the LC molecules do not reorient light, so the light polarized at the first polarizer is absorbed at the second polarizer, and the device loses transparency with increasing voltage. In this way, the electric field can be used to make a pixel switch between transparent or opaque on command. Color LCD systems use the same technique, with color filters used to generate red, green, and blue pixels. Chiral smectic liquid crystals are used in ferroelectric LCDs which are fast-switching binary light modulators. Similar principles can be used to make other liquid crystal based optical devices.


title: Liquid crystal

text: Thermotropic chiral LCs whose pitch varies strongly with temperature can be used as crude liquid crystal thermometers, since the color of the material will change as the pitch is changed. Liquid crystal color transitions are used on many aquarium and pool thermometers as well as on thermometers for infants or baths. Other liquid crystal materials change color when stretched or stressed. Thus, liquid crystal sheets are often used in industry to look for hot spots, map heat flow, measure stress distribution patterns, and so on. Liquid crystal in fluid form is used to detect electrically generated hot spots for failure analysis in the semiconductor industry.


title: Liquid crystal

text: Liquid crystal lenses converge or diverge the incident light by adjusting the refractive index of liquid crystal layer with applied voltage or temperature. Generally, the liquid crystal lenses generate a parabolic refractive index distribution by arranging molecular orientations. Therefore, a plane wave is reshaped into a parabolic wavefront by a liquid crystal lens. The focal length of liquid crystal lenses could be continuously tunable when the external electric field can be properly tuned. Liquid crystal lenses are a kind of adaptive optics. Imaging system can be benefited with focusing correction, image plane adjustment, or changing the range of depth-of-field or depth of focus. Liquid crystal lens is one of the candidates to develop vision correction device for myopia and presbyopia eyes (e.g., tunable eyeglass and smart contact lenses). Being an optical phase modulator, a liquid crystal lens feature space-variant optical path length (i.e., optical path length as the function of its pupil coordinate). In different imaging system, the required function of optical path length varies from one to another. For example, to converge a plane wave into a diffraction limited spot, for a physically-planar liquid crystal structure, the refractive index of liquid crystal layer should be spherical or paraboloidal under paraxial approximation. As for projecting images or sensing objects, it may be expected to have the liquid crystal lens with aspheric distribution of optical path length across its aperture of interest. Liquid crystal lenses with electrically tunable refractive index (by addressing the different magnitude of electric field on liquid crystal layer) have potentials to achieve arbitrary function of optical path length for modulating incoming wavefront; current liquid crystal freeform optical elements were extended from liquid crystal lens with same optical mechanisms. The applications of liquid crystals lenses includes pico-projectors, prescriptions lenses (eyeglasses or contact lenses), smart phone camera, augmented reality, virtual reality etc.


title: Liquid crystal

text: Liquid crystal lasers use a liquid crystal in the lasing medium as a distributed feedback mechanism instead of external mirrors. Emission at a photonic bandgap created by the periodic dielectric structure of the liquid crystal gives a low-threshold high-output device with stable monochromatic emission.


title: Liquid crystal

text: Polymer dispersed liquid crystal (PDLC) sheets and rolls are available as adhesive backed Smart film which can be applied to windows and electrically switched between transparent and opaque to provide privacy.


title: Liquid crystal

text: Many common fluids, such as soapy water, are in fact liquid crystals. Soap forms a variety of LC phases depending on its concentration in water.


title: Liquid crystal

text: Liquid crystal films have revolutionized the world of technology. Currently they are used in the most diverse devices, such as digital clocks, mobile phones, calculating machines and televisions. The use of liquid crystal films in optical memory devices, with a process similar to the recording and reading of CDs and DVDs may be possible.


title: Liquid crystal

text: Liquid crystals are also used as basic technology to imitate quantum computers, using electric fields to manipulate the orientation of the liquid crystal molecules, to store data and to encode a different value for every different degree of misalignment with other molecules.


title: Tetracycline

text: Tetracycline, sold under various brand names, is an oral antibiotic in the tetracyclines family of medications, used to treat a number of infections, including acne, cholera, brucellosis, plague, malaria, and syphilis.


title: Tetracycline

text: Common side effects include vomiting, diarrhea, rash, and loss of appetite. Other side effects include poor tooth development if used by children less than eight years of age, kidney problems, and sunburning easily. Use during pregnancy may harm the baby. It works by inhibiting protein synthesis in bacteria.


title: Tetracycline

text: Tetracycline was patented in 1953 and came into commercial use in 1978. It is on the World Health Organization's List of Essential Medicines. Tetracycline is available as a generic medication. Tetracycline was originally made from bacteria of the genus "Streptomyces".


title: Tetracycline

text: Tetracyclines have a broad spectrum of antibiotic action. Originally, they possessed some level of bacteriostatic activity against almost all medically relevant aerobic and anaerobic bacterial genera, both Gram-positive and Gram-negative, with a few exceptions, such as "Pseudomonas aeruginosa" and "Proteus" spp., which display intrinsic resistance. However, acquired (as opposed to inherent) resistance has proliferated in many pathogenic organisms and greatly eroded the formerly vast versatility of this group of antibiotics. Resistance amongst "Staphylococcus" spp., "Streptococcus" spp., "Neisseria gonorrhoeae", anaerobes, members of the Enterobacteriaceae, and several other previously sensitive organisms is now quite common. Tetracyclines remain especially useful in the management of infections by certain obligately intracellular bacterial pathogens such as "Chlamydia", "Mycoplasma", and "Rickettsia". They are also of value in spirochaetal infections, such as syphilis, and Lyme disease. Certain rare or exotic infections, including anthrax, plague, and brucellosis, are also susceptible to tetracyclines. Tetracycline tablets were used in the plague outbreak in India in 1994. Tetracycline is first-line therapy for Rocky Mountain spotted fever ("Rickettsia"), Lyme disease ("B. burgdorferi"), Q fever ("Coxiella"), psittacosis, "Mycoplasma pneumoniae", and nasal carriage of meningococci.


title: Tetracycline

text: It is also one of a group of antibiotics which together may be used to treat peptic ulcers caused by bacterial infections. The mechanism of action for the antibacterial effect of tetracyclines relies on disrupting protein translation in bacteria, thereby damaging the ability of microbes to grow and repair; however, protein translation is also disrupted in eukaryotic mitochondria leading to effects that may confound experimental results.


title: Tetracycline

text: The tetracyclines also have activity against certain eukaryotic parasites, including those responsible for diseases such as dysentery caused by an amoeba, malaria (a plasmodium), and balantidiasis (a ciliate).


title: Tetracycline

text: Since tetracycline is absorbed into bone, it is used as a marker of bone growth for biopsies in humans. Tetracycline labeling is used to determine the amount of bone growth within a certain period of time, usually a period around 21 days. Tetracycline is incorporated into mineralizing bone and can be detected by its fluorescence. In "double tetracycline labeling", a second dose is given 11–14 days after the first dose, and the amount of bone formed during that interval can be calculated by measuring the distance between the two fluorescent labels.


title: Tetracycline

text: Tetracycline is also used as a biomarker in wildlife to detect consumption of medicine- or vaccine-containing baits.


title: Tetracycline

text: Caution should be exercised in long-term use when breastfeeding. Short-term use is safe; bioavailability in milk is low to nil. According to the U.S. Food and Drug Administration (FDA), cases of Stevens–Johnson syndrome, toxic epidermal necrolysis, and erythema multiforme associated with doxycycline use have been reported, but a causative role has not been established.


title: Tetracycline

text: Tetracycline inhibits protein synthesis by blocking the attachment of charged tRNA at the P site peptide chain. Tetracycline blocks the A-site so that a hydrogen bond is not formed between the amino acids. Tetracycline binds to the 30S and 50S subunit of microbial ribosomes. Thus, it prevents the formation of a peptide chain. The action is usually not inhibitory and irreversible even with the withdrawal of the drug. Mammalian cells are less vulnerable to the effect of tetracyclines, despite the fact that tetracycline binds to the small ribosomal subunit of both prokaryotes and eukaryotes (30S and 40S, respectively). This is because bacteria actively pump tetracycline in, even against a concentration gradient, whereas mammalian cells are simply not affected by the mechanisms of tetracycline within the cytoplasm. This accounts for the relatively small off-site effect of tetracycline on human cells.


title: Tetracycline

text: Bacteria usually acquire resistance to tetracycline from horizontal transfer of a gene that either encodes an efflux pump or a ribosomal protection protein. Efflux pumps actively eject tetracycline from the cell, preventing the buildup of an inhibitory concentration of tetracycline in the cytoplasm. Ribosomal protection proteins interact with the ribosome and dislodge tetracycline from the ribosome, allowing for translation to continue.


title: Tetracycline

text: The tetracyclines, a large family of antibiotics, were discovered by Benjamin Minge Duggar in 1948 as natural products, and first prescribed in 1948. Benjamin Duggar, working under Yellapragada Subbarow at Lederle Laboratories, discovered the first tetracycline antibiotic, chlortetracycline (Aureomycin), in 1945. The structure of Aureomycin was elucidated in 1952 and published in 1954 by the Pfizer-Woodward group. After the discovery of the structure, researchers at Pfizer began chemically modifying aureomycin by treating it with hydrogen in the presence of a palladized carbon catalyst. This chemical reaction replaced a chlorine moiety with a hydrogen, creating a compound named tetracycline via hydrogenolysis. Tetracycline displayed higher potency, better solubility, and more favorable pharmacology than the other antibiotics in its class, leading to its FDA approval in 1954. The new compound was one of the first commercially successful semi-synthetic antibiotics that was used, and laid the foundation for the development of Sancycline, Minocycline, and later the Glycylcyclines.


title: Tetracycline

text: Our modern understanding of tetracyclines dates their discovery to 1948, but there is evidence that early inhabitants of Northeastern Africa consumed tetracycline antibiotics. Nubian mummies from between 350 and 550 C.E. were found to exhibit patterns of fluorescence identical with that of modern tetracycline labelled bone.


title: Tetracycline

text: Tetracycline has a high affinity for calcium and is incorporated into bones during the active mineralization of hydroxyapatite. When incorporated into bones, tetracycline can be identified using ultraviolet light.


title: Tetracycline

text: It is conjectured that the beer brewed at the time was the source of the tetracycline found in these bones.


title: Tetracycline

text: According to data from EvaluatePharma and published in the "Boston Globe", in the USA the price of tetracycline rose from $0.06 per 250-mg pill in 2013 to $4.06 a pill in 2015. The "Globe" described the "big price hikes of some generic drugs" as a "relatively new phenomenon" which has left most pharmacists "grappling" with large upswings" in the "costs of generics, with 'overnight' price changes sometimes exceeding 1,000%."


title: Tetracycline

text: It is marketed under the brand names Sumycin, Tetracyn, and Panmycin, among others. Actisite is a thread-like fiber formulation used in dental applications.


title: Tetracycline

text: It is also used to produce several semisynthetic derivatives, which together are known as the tetracycline antibiotics. The term "tetracycline" is also used to denote the four-ring system of this compound; "tetracyclines" are related substances that contain the same four-ring system.


title: Tetracycline

text: Due to the drug's association with fighting infections, it serves as the main "commodity" in the science fiction series Aftermath, with the search for tetracycline becoming a major preoccupation in later episodes.


title: Tetracycline

text: In genetic engineering, tetracycline is used in transcriptional activation. It has been used as an engineered "control switch" in chronic myelogenous leukemia models in mice. Engineers were able to develop a retrovirus that induced a particular type of leukemia in mice, and could then "switch" the cancer on and off through tetracycline administration. This could be used to grow the cancer in mice and then halt it at a particular stage to allow for further experimentation or study.


title: Tetracycline

text: A technique being developed for the control of the mosquito species "Aedes aegypti" (the infection vector for yellow fever, dengue fever, Zika fever, and several other diseases) uses a strain that is genetically modified to require tetracycline to develop beyond the larval stage. Modified males raised in a laboratory develop normally as they are supplied with this chemical and can be released into the wild. Their subsequent offspring inherit this trait, but find no tetracycline in their environments, so never develop into adults.


title: Muhteşem Yüzyıl: Kösem

text: Muhteşem Yüzyıl: Kösem (, ) is a Turkish television sequel to the 2011 Turkish television period drama "Muhteşem Yüzyıl". Written by Yılmaz Şahin, it recounts the life of Mahpeyker Kösem Sultan, a slave girl who became the most powerful woman in Ottoman history after she was captured and sent to the harem of Sultan Ahmed I. Actresses Nurgül Yeşilçay, Beren Saat and Anastasia Tsilimpiou played the titular role in three different ages of her life, while actors Ekin Koç, Boran Kuzum, Taner Ölmez, Metin Akdülger and Tugay Mercan were cast as different sultans of the Ottoman dynasty. Also in the starring cast were actresses Hülya Avşar, Tülin Özen, Leyla Feray, Farah Zeynep Abdullah, Aslıhan Gürbüz and Hande Doğandemir, who played prominent roles of different sultanas in the series.


title: Muhteşem Yüzyıl: Kösem

text: The first few episodes of the series were filmed in Chios, Greece. An excerpt of the show was screened in Cannes, France, at the annual international television festival MIPCOM about a month before its official premiere on Star TV on November 12, 2015. It was later transferred to FOX for its second season. Since its broadcast, "Muhteşem Yüzyıl: Kösem" has been aired in several countries.


title: Muhteşem Yüzyıl: Kösem

text: Its final episode aired on 27 June 2017. The series' finale marked the end of the six-year "Muhteşem Yüzyıl" saga.


title: Muhteşem Yüzyıl: Kösem

text: Sultan Ahmed I, who unexpectedly ascended the throne after the sudden death of his father, vows that he would not murder his younger brother, Mustafa. Meanwhile, Anastasia, who was brought to the palace by order of Safiye Sultan, is gifted to Ahmed as a slave. Although Anastasia initially wanted to return to her home and family, she falls in love with the young sultan and adopts the name Kösem. Kösem increases her dominance in the palace by giving birth to four princes and four princesses and by defeating all her enemies. She becomes Ahmed's chief consort, or Haseki Sultan, and thus puts an end to the reign of Safiye Sultan in the Ottoman harem. Years later, when Sultan Ahmed passes away, the black winter just started for Kösem Sultan. With the agnatic seniority system enforced following Ahmed's death, his younger brother Şehzade Mustafa ascends the throne as Mustafa I, but as his mental health deteriorates, he is dethroned and replaced by Kösem Sultan's step-son, Osman. As Sultan Osman II grows wary of his stepmother Kösem's increasing power, he banished her to the old palace and attempts to establish a new army in place of the Janissary army. He is eventually deposed by the janissaries and brutally murdered in the Yedikule Dungeons, and his uncle Sultan Mustafa ascends the throne for the second time. Later, he is dethroned by Kösem Sultan and her son Şehzade Murad becomes the new sultan. Safiye Sultan gives Kösem Sultan the Hürrem Sultan’s ring when she was killing herself. Also, Sultan Ahmed gave Kösem Sultan Hürrem Sultan’s crown. The palace still talks about Hürrem, Nurbanu Sultan and Safiye Sultan as the most powerful women’s in the World.


title: Muhteşem Yüzyıl: Kösem

text: Kösem has been the all-powerful Valide Sultan and regent to her son Sultan Murad IV for nearly a decade, when the military unrest causes the latter to deprive her of her authority and the two clash. With the control of the state fully in his hands, Murad sets his plans of restoring the empire to the times of prosperity and conquest and checking corruption in motion. At the same time, the Hungarian princess Farya Bethlen seeks refuge at the Ottoman court and the instant attraction between her and the Sultan causes reactions from Kösem and Murad's favourite consort, Ayşe Sultan. A strain is also put on Murad's relationship with his sister Gevherhan after the execution of her husband, as well as in hers with their mother, when she eventually opts for love instead of power games. Their half-brother and Crown Prince, Bayezid, though loyal himself to the sultan, is drawn in conflict too, due to the ambitions of his mother, Gülbahar, who has been long obscured by Kösem; all the while, the agendas of the other princes and those of the European powers remain unknown and anti-Ottoman sentiments and plans resurface in the West.


title: Muhteşem Yüzyıl: Kösem

text: The second season also introduces the reign of Sultan Ibrahim, the clash between Kösem and her daughter-in-law, Turhan for the position of Valide Sultan, concluding the series with Kösem's assassination. After Kösem Sultan’s death, Turhan Sultan takes the Hürrem Sultan’s ring and becomes the only and the most powerful women in the empire.


title: Quincy Jones III

text: Quincy Delight Jones III (born 23 December 1968), better known as QDIII, QD3 and Snoopy, is an English-born Swedish-American music producer and film producer.


title: Quincy Jones III

text: Jones was born in Wimbledon, London, the son of Swedish model Ulla Andersson and American musician-music producer Quincy Jones Jr. He grew up in Sweden with his older sister Martina after their parents legally separated. The two have five American half-sisters by their father's two other marriages and relationships in the United States, including the actresses Kidada and Rashida Jones and fashion model Kenya Kinski-Jones.


title: Quincy Jones III

text: Jones is the founder of QD3 Entertainment, which has produced a series of documentaries known collectively as "Beef." These explore the violence and feuds within hip hop culture. Jones is also a hip hop DJ; he released an album called "Soundlab" (1991).


title: Quincy Jones III

text: On 4 November 2009, Chamillionaire launched the Global Innovation Tournament 2009 with Jones at Stanford University as part of the Stanford Entrepreneurial Thought Leaders Seminar Series.


title: Quincy Jones III

text: Jones is known for his documentary "The Carter" (2009), about rapper Lil Wayne. Lil Wayne filed a lawsuit to prevent distribution because he wanted control over the final cut, but the case was dismissed by the judge. A "Huffington Post" review ranked it as one of the top five movies about hip-hop.


title: Quincy Jones III

text: In 2011, Jones co-founded the health and wellness lifestyle company Feel Rich, Inc. with partner Shawn Ullman, which aimed at promoting "health as the new wealth" to urban communities. Along with QD3's father, Grammy winning producer Quincy Jones, they produced a documentary film, Feel Rich:Health is the New Wealth, that featured celebrities, hip hop icons, and medical and health professionals discussing wellness in the urban community.


title: Quincy Jones III

text: In January 2014, Jones founded WeMash, an Internet service that connects owners of content (movie studios, news organizations, sports entities, music labels/publishers) with creators from every field (video artists, filmmakers, musicians, and more) to reimagine content beyond its original context. Investors include venture capital firm Andreessen Horowitz.


title: Ryan Potter

text: Ryan Potter (born September 12, 1995) is an American actor and voice actor. He made his acting debut as the lead of the Nickelodeon action comedy series "Supah Ninjas" (2011–2013). As a voice actor, he voiced Hiro Hamada in the animated superhero film "Big Hero 6" (2014), its (2017–2021) and the Disney+ series "Baymax!" (2022). Potter also portrays Gar Logan / Beast Boy on the DC Universe / HBO Max superhero series "Titans" (2018–present).


title: Ryan Potter

text: Potter was born in Portland, Oregon on September 12, 1995. His mother, Jordanna Potter-Lew, is Jewish American and his father is Japanese. He uses his mother's maiden name. He was raised in Tokyo, Japan, until returning to the United States when he was seven. He was raised by his single mother. Potter's first language was Japanese; however, he is no longer fluent. At the age of eight, he began studying White Tiger kung fu, a discipline which he would continue to pursue throughout his teenage years. Other childhood interests reportedly included baseball, skateboarding, and playing the drums.


title: Ryan Potter

text: In 2010, Potter began his acting career at the age of 15 when he received a leaflet in his kung fu class announcing Nickelodeon was looking for teenagers to star in a new martial-arts themed program entitled "Supah Ninjas". After a few days of considering an acting career, Potter decided to audition, eventually landing the series' lead role of Mike Fukanaga, a typical American teen who discovers he is a descendant from a long line of ninjas. In March 2012, Nickelodeon announced it had renewed "Supah Ninjas" for a second season.


title: Ryan Potter

text: Following the premiere of "Supah Ninjas" in January 2011, he became one of Nickelodeon's popular young stars, featured in numerous teen magazines and making personal appearances in the network's special "Nickelodeon's Worldwide Day of Play" and its reboot of "Figure It Out", as well as an appearance on its sister network's broadcast of the 2011 TeenNick HALO Awards. In March 2012, Potter began a recurring role on "", portraying Fred's best friend.


title: Ryan Potter

text: Potter later voiced "Big Hero 6" protagonist Hiro Hamada and reprised his role in the and "Kingdom Hearts III".


title: Ryan Potter

text: Potter was also lobbying for the role of Tim Drake and created a concept fight scene using the character's signature bō staff as an audition. He ended the video with a plea to Ben Affleck to cast him as Robin. He was then cast as Beast Boy (or Garfield "Gar" Logan) in Warner Bros.'s live-action Titans series.


title: Ryan Potter

text: In 2011, Potter founded the organization Toy Box of Hope, a charity which holds an annual holiday collection drive for children in homeless shelters and transitional living facilities in the Los Angeles area. During the second annual event in 2012, Potter spoke of the focus of the organization, stating "[W]hat we want to do is provide bedsheets, jackets and toys to [homeless shelters], so these kids are like, 'Wow, someone cares, there's hope.'" In 2012, Potter was reportedly planning to expand Toy Box of Hope to include a "Birthday Party Box" program.


title: Ryan Potter

text: In June 2012, Potter became one of the youngest celebrities to lend his voice to California's No H8 Campaign in support of same-sex marriage. When explaining his involvement, 16-year-old Potter stated, "I know what it feels like to be bullied. And I will not tolerate the thought of anyone, for any reason, being bullied. It starts with young people, and it can end with young people. As we learn to embrace our diversity, we become stronger, more tolerant. The differences are beautiful. The differences matter. It's what makes life an adventure."


title: Miranda Rae Mayo

text: Miranda Rae Mayo is an American television actress. She starred as Lacey Briggs on "Blood & Oil" (2015) and has appeared on "Chicago Fire" as Lieutenant Stella Kidd since 2016.


title: Miranda Rae Mayo

text: Mayo was born in Fresno, California and began her acting career appearing in the local stage productions and at her high school Roosevelt High School. She relocated to Los Angeles and began a modeling career before making her television debut. In 2011, Mayo guest-starred in an episode of the short-lived NBC police series, "".


title: Miranda Rae Mayo

text: In 2013, she had a recurring role in the BET comedy series "The Game". The following year she joined the cast of "Days of Our Lives" as Zoe Browning. She appeared on the show on a recurring basis from August 2014 to July 2015. In early 2015, Mayo had the recurring role as Talia Sandoval during the fifth season of the Freeform teen drama series "Pretty Little Liars".


title: Miranda Rae Mayo

text: In 2015 she appeared in the second season of HBO anthology crime series "True Detective", and was cast in the recurring role of the Showtime drama series "The Affair" as the new love interest of Joshua Jackson's character's. In the same year, Mayo was cast in the series regular role in the ABC prime time soap opera "Blood & Oil" as Lacey Briggs, the daughter of oil tycoon Hap Briggs (Don Johnson).


title: Hydrogen fuel

text: Hydrogen fuel refers to hydrogen which is burned as fuel with oxygen. It is zero-carbon, provided that it is created in a process that does not involve carbon. It can be used in fuel cells or internal combustion engines (see HICEV). Regarding hydrogen vehicles, hydrogen has begun to be used in commercial fuel cell vehicles such as passenger cars, and has been used in fuel cell buses for many years. It is also used as a fuel for spacecraft propulsion and is being proposed for hydrogen-powered aircraft.


title: Hydrogen fuel

text: Because pure hydrogen does not occur naturally on Earth in large quantities, it usually requires a primary energy input to be produced on an industrial scale. Hydrogen fuel can be produced from methane or by electrolysis of water. As of 2020, the majority of hydrogen (∼95%) is produced from fossil fuels by steam reforming or partial oxidation of methane and coal gasification with only a small quantity by other routes such as biomass gasification or electrolysis of water.


title: Hydrogen fuel

text: Steam–methane reforming, the current leading technology for producing hydrogen in large quantities, extracts hydrogen from methane. However, this reaction releases fossil carbon dioxide and carbon monoxide into the atmosphere, which are greenhouse gases exogenous to the natural carbon cycle, and thus contribute to climate change. In electrolysis, electricity is run through water to separate the hydrogen and oxygen. This method can use wind, solar, geothermal, hydro, fossil fuels, biomass, nuclear, and many other energy sources. Obtaining hydrogen from this process is being studied as a viable way to produce domestically at a low cost. Researchers are also developing artificial leaves which integrate light absorbers with catalysts, and can produce hydrogen directly from water. While this technology is still at an early stage, floating farms of lightweight devices may potentially supply remote communities.


title: Hydrogen fuel

text: The world's largest facility for producing hydrogen fuel is claimed to be the Fukushima Hydrogen Energy Research Field (FH2R), a 10 MW-class hydrogen production unit, inaugurated in March 2020, in Namie, Fukushima Prefecture. The site occupies 180,000 m of land, much of which is occupied by a solar array; power from the grid is also used for electrolysis of water to produce hydrogen fuel.


title: Hydrogen fuel

text: Production is usually classed in terms of colour labels; 'grey hydrogen' is produced as a by-product of an industrial process, 'blue hydrogen' is produced through a production process where is also produced then subsequently captured via CCS, and finally 'green hydrogen' is produced entirely from renewable sources.


title: Hydrogen fuel

text: Hydrogen is found in the first group and the first period in the periodic table, i.e., it is the lightest element. Hydrogen is rarely found in its pure form in the atmosphere, H. In flame of pure hydrogen burning in air, the hydrogen (H) reacts with oxygen (O) to form water (HO) with the release of energy.


title: Hydrogen fuel

text: In atmospheric air rather than pure oxygen, hydrogen combustion may yield a small amount of nitrogen oxides with the water vapor. The energy released allows hydrogen to be used as a fuel. In an electrochemical cell, that energy can be used with relatively high efficiency. If the energy is used to produce heat, thermodynamics places limits on the thermal efficiency of the process.


title: Hydrogen fuel

text: Hydrogen is usually considered to be an energy carrier, like electricity, as it must be produced from a primary energy source such as solar energy, biomass, electrical energy (e.g. in the form of solar PV or via wind turbines), or hydrocarbons such as natural gas or coal. Conventional hydrogen production using natural gas induces significant environmental impacts; as with the use of any hydrocarbon, carbon dioxide is emitted. At the same time, the addition of 20% hydrogen (an optimal share that does not affect gas pipes and appliances) to natural gas can reduce emissions from heating and cooking. Hydrogen is locked up in enormous quantities in water, hydrocarbons, and other organic matter.


title: Hydrogen fuel

text: One of the challenges of using hydrogen as a fuel comes from being able to extract hydrogen efficiently from these compounds. Currently, steam reforming, which combines high-temperature steam with natural gas, accounts for the majority of the hydrogen produced. This method of hydrogen production occurs at 700–1100 °C, and has an efficiency of 60–75%. Hydrogen can also be produced from water through electrolysis, which is less carbon-intensive if the electricity used to drive the reaction does not come from fossil-fuel power plants but rather from renewable or nuclear energy sources. The efficiency of water electrolysis is about 70–80%, with a goal of 82–86% efficiency by 2030 using proton exchange membrane (PEM) electrolyzers.


title: Hydrogen fuel

text: Other methods for producing hydrogen for fuel are also currently being tested. Renewable liquid reforming is the process of taking liquid fuels, like ethanol, and reacting with high-temperature steam to produce hydrogen near the point of end use. In the presence of a catalyst, hydrogen, carbon monoxide and carbon dioxide are produced. The resulting carbon monoxide is reacted at high-temperatures with steam to produce more carbon dioxide and hydrogen in a "water-gas shift reaction". Then the hydrogen is separated and purified. Another method is using starch-rich feedstocks to ferment to produce hydrogen. This is known as dark fermentation and uses anaerobic bacteria primarily to ferment mainly carbohydrates into hydrogen. Other processes are photoheterotrophic processes. In this process, a prokaryotic microorganism called pure non-sulfur bacteria (PNS) or green algae reacts with light to produce hydrogen, via a pathway of photosynthesis. Unlike dark fermentation, these processes use enzymes like hydrogenase and nitrogenase for generation of molecular hydrogen.


title: Hydrogen fuel

text: Currently, the breakdown of hydrogen gas production is mainly coming from fossil fuels. In fact, 96% of hydrogen is produced directly from fossil fuels, the majority of which coming from natural gas (48%). Only 4% of hydrogen is produced indirectly from fossil fuels by electrolysis with no breakdown in green hydrogen.


title: Hydrogen fuel

text: Green hydrogen is any hydrogen that is produced from renewable energy. This includes electrolysis with electricity coming from green sources such as solar, wind, and hydroelectric power. Blue hydrogen is hydrogen that is produced from natural gas in advanced processes which emit greenhouse gas emissions. Grey hydrogen is produced from steam methane reforming, or steam reforming, which has a higher greenhouse gas emission total than blue hydrogen. Finally, brown hydrogen is produced from coal in Coal Classification which has one of the highest greenhouse gas emissions per ton of hydrogen produced. Thermochemical water splitting ins the newest source of green hydrogen production beyond hydrolysis. Using chlorine and sulfur, in the presence of a nuclear reactor, sunlight can be focused above a solar thermochemical hydrogen (STCH) reactor to produce hydrogen.


title: Hydrogen fuel

text: Once produced, hydrogen can be used in much the same way as natural gas – it can be delivered to fuel cells to generate electricity and heat, used in a combined cycle gas turbine to produce larger quantities of centrally produced electricity or burned to run a combustion engine; all methods producing no carbon or methane emissions. In each case hydrogen is combined with oxygen to form water. This is also one of its most important advantages as hydrogen fuel is environmentally friendly. The heat in a hydrogen flame is a radiant emission from the newly formed water molecules. The water molecules are in an excited state on the initial formation and then transition to a ground state; the transition releasing thermal radiation. When burning in air, the temperature is roughly 2000 °C (the same as natural gas).


title: Hydrogen fuel

text: Historically, carbon compounds have been the most practical carriers of energy, as hydrogen and carbon combined are more volumetrically dense, although hydrogen itself has three times the specific energy (energy per unit mass) as methane or gasoline. Although hydrogen is the lightest element and thus has a slightly higher propensity to leak from older natural gas pipes such as those made from iron, leakage from plastic (polyethylene PE100) pipes is expected to be very low at about 0.001%.


title: Hydrogen fuel

text: The reason that steam–methane reforming has traditionally been favoured over electrolysis is that whereas methane reforming directly uses natural gas as a source of energy, electrolysis requires electrical energy for this. When the cost of producing electrical energy (via wind turbines and solar PV) falls below the cost of natural gas, electrolysis will become cheaper than SMR.


title: Hydrogen fuel

text: Before natural gas became generally available, in some cases tonnage hydrogen was produced for industry by water electrolysis, although not for use as a fuel. In a plant located at Risdon, Tasmania, Australia, designed to produce 60,963 tonne per annum of ammonium sulfate fertilizer, ammonia was synthesised by reacting nitrogen and hydrogen. The nitrogen was obtained by distilling liquid air and the hydrogen was made by electrolysing water. The design hydrogen production rate was 2,790 tonne per annum and the design ammonia production rate was 15,714 tonne per annum. Production commenced in late 1956 and the plant ran until 1986. Mercury arc rectifiers were used. Some ammonia production continued until 1993. The electricity for electrolysis was generated by hydro-electric power stations.


title: Hydrogen fuel

text: Hydrogen fuel can provide motive power for liquid-propellant rockets, cars, trucks, trains, boats and airplanes, portable fuel cell applications or stationary fuel cell applications, which can power an electric motor. Hydrogen is considered as the primary sustainable source of renewable energy and is "highly required for advanced energy conversion systems."


title: Hydrogen fuel

text: The problems of using hydrogen fuel in cars arise from hydrogen being difficult to store in either a high pressure tank or a cryogenic tank. Alternative storage media such as within complex metal hydrides are in development. In general, batteries are more suitable for vehicles the size of cars or smaller, but hydrogen may be better for larger vehicles such as heavy trucks, because hydrogen energy storage offers greater range and quicker refuelling time.


title: Hydrogen fuel

text: Hydrogen fuel can also be used to power stationary power generation plants, or to provide an alternative to natural gas for heating.


title: Hydrogen fuel

text: Fuel cells present the most attractive choice for energy conversion from hydrogen to electrical power, due to their high efficiency, low noise, and a limited number of moving parts. Fuel cells are of interest for both stationary and mobile power generation from hydrogen. Fuel cells are often considered as part of a vehicle propulsion system.


title: Hydrogen fuel

text: Using a fuel cell to power an electrified powertrain including a battery and an electric motor is two to three times more efficient than using a combustion engine, although some of this benefit is related to the electrified powertrain (i.e., including regenerative braking). This means that significantly greater fuel economy is available using hydrogen in a fuel cell, compared to that of a hydrogen combustion engine.


title: Hydrogen fuel

text: Alongside mono-fuel hydrogen combustion, combustion engines in commercial vehicles have the potential to be converted to run on a hydrogen–diesel mix. This has been demonstrated in prototypes in the UK, where their emissions have been reduced by up to 40% during normal driving conditions. This dual-fuel flexibility eliminates range anxiety as the vehicles can alternatively fill up only on diesel when no hydrogen refuelling is available. Relatively minor modifications are needed to the engines, as well as the addition of hydrogen tanks at a compression of 350 bars.


title: Hydrogen fuel

text: Trials are underway to test the efficiency of the 100% conversion of a Volvo FH16 heavy-duty truck to use only hydrogen. The range is expected to be 300 km/17 kg; which means an efficiency better than a standard diesel engine (where the embodied energy of 1 gallon of gasoline is equal to 1 kilogram of hydrogen).


title: Hydrogen fuel

text: Compared to conventional fuels, if a low price for hydrogen (€5/kg), significant fuel savings could be made via such a conversion in Europe or the UK. A lower price would be needed to compete with diesel/gasoline in the US, since these fuels are not taxed as much.


title: Hydrogen fuel

text: Combustion engines using hydrogen are of interest since the technology offers a less substantial change to the automotive industry, and potentially a lower up-front cost of the vehicle compared to fully electric or fuel cell alternatives. However, the non-zero emission nature of the engine means it will not be able to operate in city zero emission zones, unless part of a hybrid powertrain.


title: Hydrogen fuel

text: Hydrogen has a high energy content per unit mass. However, at room temperature and atmospheric pressure, it has a very low energy content per unit volume compared to liquid fuels or even to natural gas. For this reason, it is usually either compressed or liquefied by lowering its temperature to under 33 K. High-pressure tanks weigh much more than the hydrogen they can hold. For example in the 2014 Toyota Mirai, a full tank contains only 5.7% by weight of hydrogen, the rest of its mass being that of the tank.


title: Hydrogen fuel

text: Hydrogen fuel is hazardous because of its low ignition energy and high combustion energy, and because it tends to leak easily from tanks. Explosions at hydrogen filling stations have been reported. Hydrogen fuelling stations, like petrol, generally receive deliveries of hydrogen by truck from hydrogen suppliers. An interruption at a supply facility can shut down multiple fuelling stations.


title: Ulrika Jonsson

text: Eva Ulrika Jonsson (born 16 August 1967) is a Swedish-British television presenter and model. She became known as a TV-am weather presenter, moved on to present the ITV show "Gladiators", and as a team captain of the BBC Two show "Shooting Stars".


title: Ulrika Jonsson

text: After working as a secretary, Jonsson began her television career on TV-am in 1989, as a weather presenter on "Good Morning Britain". From 12 September 1989, she was also the weather presenter for Swedish TV3, broadcasting from London. In 1991, she co-presented BBC One's short-lived daytime quiz show "Who's Bluffing Who?" with Richard Cartridge, and starred in the French film, "The Annunciation of Marie" (1991). In 1992, she moved into mainstream presenting and played host to numerous shows including ITV's "Gladiators", "The National Lottery Draws" – plus two major international broadcasts, the Eurovision Song Contest in 1998 and Miss World in 1999. She also modelled for Playtex Lingerie during this period and was a team captain on the BBC TV quiz show "Shooting Stars".


title: Ulrika Jonsson

text: In 1997, she interviewed the then British Prime Minister John Major for the BBC 2 programme, "The Enormous Election". In 1998, she interviewed the then Chancellor of the Exchequer, Gordon Brown, for her programme "Ulrika in Euroland".


title: Ulrika Jonsson

text: She presented "Eurovision Song Contest" in 1998 when it was hosted in Birmingham, alongside Sir Terry Wogan; later that year she co-hosted the Royal Variety Performance alongside Ronan Keating at the Lyceum Theatre in London. Following this, she co-hosted Miss World 1999 with Melanie Sykes at the Olympia Hall in London. Jonsson was booked to host Channel 5's reality game show "Jailbreak" in Autumn 2000 but had to pull out of the project due to health concerns over her newborn child. She was replaced as main host by Craig Charles. Jonsson later presented BBC One game show "Dog Eat Dog", broadcast from April 2001 to November 2002, and "The Joy of Text" in June 2001 alongside Terry Alderton.


title: Ulrika Jonsson

text: In 2002, Jonsson presented the first series of ITV makeover show "Home On Their Own", a show where children made alterations to their house (how they wanted the house to be) during the course of a weekend, while their parents went on holiday. Some of the home improvements included an Austin Powers room, individual doorbells for the children and a cinema living room. Jonsson did not return for the second series, which was hosted by Tess Daly the following year.


title: Ulrika Jonsson

text: In 2002, she was the subject of a Channel 4 documentary, "Ulrika Jonsson: the Truth About Men". The programme featured a candid interview with Jonsson, received heavy press attention and attracted 2.8 million viewers.


title: Ulrika Jonsson

text: After intense media attention relating to events in her personal life, Jonsson decided to return to Sweden. The Swedish television network TV3 offered her the role as hostess of the Miss Sweden beauty pageant. She accepted the invitation. In March 2003, Jonsson was a contestant on the BBC's "Comic Relief Does Fame Academy". In 2005, she appeared with four other celebrities on Channel 4's daytime show "Come Dine with Me". On 20 January 2007, she joined 10 other celebrities to take part in the ITV reality TV show "Dancing on Ice", where she was partnered with Pavel Aubrecht. With previous skating experience in her native Sweden, Jonsson was expected to go far in the event but finished 9th after being beaten in the skate-off by Kay Burley during week 3.