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Synthetic Molecular Motor
Synthetic molecular motors are molecular machines capable of continuous directional rotation under an energy input. Although the term "molecular motor" has traditionally referred to a naturally occurring protein that induces motion (via protein dynamics), some groups also use the term when referring to non-biological, non-peptide synthetic motors. Many chemists are pursuing the synthesis of such molecular motors. The basic requirements for a synthetic motor are repetitive 360° motion, the consumption of energy and unidirectional rotation. The first two efforts in this direction, the chemically driven motor by Dr. T. Ross Kelly of Boston College with co-workers and the light-driven motor by Ben Feringa and co-workers, were published in 1999 in the same issue of Nature. As of 2020, the smallest atomically precise molecular machine has a rotor that consists of four atoms. Chemically driven rotary molecular motors An example of a prototype for a synthetic chemically driven rotar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MD Rotor 250K 1ns
MD, Md, mD or md may refer to: Places * Moldova (ISO country code MD) * Maryland (US postal abbreviation MD) * Magdeburg (vehicle plate prefix MD), a city in Germany * Mödling District (vehicle plate prefix MD), in Lower Austria, Austria People * Muhammad (name) or Mohammed (Md) Arts, entertainment, and media Music * ' or ' (MD or m.d.; "right hand"), in piano scores * Music director * Mini Disc Other arts, entertainment, and media * ''MDs'' (TV series), 2002 * ', ("Materials and discussions for the analysis of classical texts"), an Italian journal Brands and enterprises * Air Madagascar, IATA airline code * McDonnell Douglas aircraft model prefix * MD Helicopters Science and technology Biology and medicine * Doctor of Medicine, a medical degree * Medial dorsal nucleus, a cluster of neurons in the thalamus * Muscular dystrophy, a group of diseases involving breakdown of skeletal muscles * Ménière's disease, a disorder of the inner ear * MD (Ayurveda), a degree in Indian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratchet (device)
A ratchet (occasionally spelled rachet) is a mechanical device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Ratchets are widely used in machinery and tools. The word ''ratchet'' is also used informally to refer to a ratcheting socket wrench. __TOC__ Theory of operation A ratchet consists of a round gear or a linear rack with teeth, and a pivoting, spring-loaded finger called a '' pawl'' (or ''click'', in clocks and watches) that engages the teeth. The teeth are uniform but are usually asymmetrical, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge. When the teeth are moving in the unrestricted (i.e. forward) direction, the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing it (often with an audible 'click') into the depression between the teeth as it passes the tip of each tooth. When the teeth move in the opposite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Helicity
In plasma physics, magnetic helicity is a measure of the linkage, twist, and writhe of a magnetic field. In ideal magnetohydrodynamics, magnetic helicity is conserved. When a magnetic field contains magnetic helicity, it tends to form large-scale structures from small-scale ones. This process can be referred as an inverse transfer in Fourier space. This second property makes magnetic helicity special: three-dimensional turbulent flows tend to "destroy" structure, in the sense that large-scale vortices break-up in smaller and smaller ones (a process called "direct energy cascade", described by Lewis Fry Richardson and Andrey Nikolaevich Kolmogorov). At the smallest scales, the vortices are dissipated in heat through viscous effects. Through a sort of "inverse cascade of magnetic helicity", the opposite happens: small helical structures (with a non-zero magnetic helicity) lead to the formation of large-scale magnetic fields. This is for example visible in the heliospheric curren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moiety ''
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Moiety may refer to: Chemistry * Moiety (chemistry), a part or functional group of a molecule ** Moiety conservation, conservation of a subgroup in a chemical species Anthropology * Moiety (kinship), either of two groups into which a society is divided ** A division of society in the Iroquois government and societal structure ** An Australian Aboriginal kinship group ** Native Hawaiian realm ruled by a moʻi or an aliʻi Law * Moiety title, ownership of part of a property Entertainment * ''Moiety'', a 2012 album by Keith Kenniff (as Helios) * Moiety, a rebel group in the computer game ''Riven ''Riven'' is a Adventure game#Puzzle adventure, puzzle adventure video game. It is the sequel to ''Myst'' and second in the Myst (series), ''Myst'' series of games. Developed by Cyan Worlds, it was initially published by Red Orb Entertainment, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as a placeholder for the aryl group in chemical structure diagrams, analogous to “R” used for any organic substituent. “Ar” is not to be confused with the elemental symbol for argon. A simple aryl group is phenyl (), a group derived from benzene. Examples of other aryl groups consist of: * The tolyl group () which is derived from toluene (methylbenzene) * The xylyl group (), which is derived from xylene (dimethylbenzene) * The naphthyl group (), which is derived from naphthalene Arylation is the process in which an aryl group is attached to a substituent. It is typically achieved by cross-coupling reactions. Nomenclature The most basic aryl group is phenyl, which is made up of a benzene ring with one hydrogen atom substituted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feringa Chem Motor
Bernard Lucas Feringa (, born 18 May 1951) is a Dutch synthetic organic chemist, specializing in molecular nanotechnology and homogeneous catalysis. He is the Jacobus van 't Hoff Distinguished Professor of Molecular Sciences, at the Stratingh Institute for Chemistry, University of Groningen, Netherlands, and an Academy Professor of the Royal Netherlands Academy of Arts and Sciences. He was awarded the 2016 Nobel Prize in Chemistry, together with Sir J. Fraser Stoddart and Jean-Pierre Sauvage, "for the design and synthesis of molecular machines". Personal life Feringa was born as the son of farmer Geert Feringa (1918–1993) and his wife Lies Feringa née Hake (1924–2013). Feringa was the second of ten siblings in a Catholic family. He spent his youth on the family's farm, which is directly on the border with Germany, in Barger-Compascuum in the Bourtange moor. He is of Dutch and German descent. Among his ancestors is the settler Johann Gerhard Bekel. Together with hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactone
Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the corresponding hydroxycarboxylic acids, which takes place spontaneously when the ring that is formed is five- or six-membered. Lactones with three- or four-membered rings (α-lactones and β-lactones) are very reactive, making their isolation difficult. Special methods are normally required for the laboratory synthesis of small-ring lactones as well as those that contain rings larger than six-membered. Nomenclature Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biaryl
Biphenyl (also known as diphenyl, phenylbenzene, 1,1′-biphenyl, lemonene or BP) is an organic compound that forms colorless crystals. Particularly in older literature, compounds containing the functional group consisting of biphenyl less one hydrogen (the site at which it is attached) may use the prefixes xenyl or diphenylyl. It has a distinctively pleasant smell. Biphenyl is an aromatic hydrocarbon with a molecular formula (C6H5)2. It is notable as a starting material for the production of polychlorinated biphenyls (PCBs), which were once widely used as dielectric fluids and heat transfer agents. Biphenyl is also an intermediate for the production of a host of other organic compounds such as emulsifiers, optical brighteners, crop protection products, and plastics. Biphenyl is insoluble in water, but soluble in typical organic solvents. The biphenyl molecule consists of two connected phenyl rings. Properties and occurrence Biphenyl occurs naturally in coal tar, crude oil, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Racemic Mixture
In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. History The first known racemic mixture was racemic acid, which Louis Pasteur found to be a mixture of the two enantiomeric isomers of tartaric acid. He manually separated the crystals of a mixture by hand, starting from an aqueous solution of the sodium ammonium salt of racemate tartaric acid. Pasteur benefited from the fact that ammonium tartrate salt that gives enantiomeric crystals with distinct crystal forms (at 77 °F). Reasoning from the macroscopic scale down to the molecular, he reckoned that the molecules had to have non-superimposable mirror images. A sample with only a single enantiomer is an ''enantiomerically pure'' or ''enantiopure'' compound. Etymology From racemic acid found in grapes; from Latin ''racemus'', meani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring-opening Reaction
A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where all the atoms are carbon (i.e., are carbocycles), none of the atoms are carbon (inorganic cyclic compounds), or where both carbon and non-carbon atoms are present (heterocyclic compounds). Depending on the ring size, the bond order of the individual links between ring atoms, and their arrangements within the rings, carbocyclic and heterocyclic compounds may be aromatic or non-aromatic; in the latter case, they may vary from being fully saturated to having varying numbers of multiple bonds between the ring atoms. Because of the tremendous diversity allowed, in combination, by the valences of common atoms and their ability to form rings, the number of possible cyclic structures, even of small size (e.g., < 17 total atoms) numbers in the many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoselectivity
In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non- stereospecific creation of a new stereocenter or during a non-stereospecific transformation of a pre-existing one. The selectivity arises from differences in steric and electronic effects in the mechanistic pathways leading to the different products. Stereoselectivity can vary in degree but it can never be total since the activation energy difference between the two pathways is finite. Both products are at least possible and merely differ in amount. However, in favorable cases, the minor stereoisomer may not be detectable by the analytic methods used. An enantioselective reaction is one in which one enantiomer is formed in preference to the other, in a reaction that creates an optically active product from an achiral starting material, using either a chiral catalyst, an enzyme or a chiral reagent. The degree of selectivity is meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David Leigh (scientist)
David Alan Leigh (born 1963) FRS FRSE FRSC is a British chemist, Royal Society Research Professor and, since 2014, the Sir Samuel Hall Chair of Chemistry in the Department of Chemistry at the University of Manchester. He was previously the Forbes Chair of Organic Chemistry at the University of Edinburgh (2001–2012) and Professor of Synthetic Chemistry at the University of Warwick (1998–2001). Education Leigh was educated at Codsall Community High School and the University of Sheffield. Career and research He is noted for the invention of fundamental methods to control molecular-level dynamics and entanglement, including strategies to construct rotaxanes, catenanes and molecular knots and some of the earliest synthetic molecular motors, molecular robots and functional nanomachines. Using mechanically-interlocked molecular architectures he prepared a novel molecular information ratchet that employs a mechanism reminiscent of Maxwell's demon (although it requires an energy i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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