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Tholin
Tholins (after the Greek (') "hazy" or "muddy"; from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet or cosmic ray irradiation of simple carbon-containing compounds such as carbon dioxide (), methane () or ethane (), often in combination with nitrogen () or water ().Sarah Hörs"What in the world(s) are tholins?" Planetary Society, July 23, 2015. Retrieved 30 Nov 2016. Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups, typically nitriles and hydrocarbons and their degraded forms such as amines and phenyls. Tholins do not form naturally on modern-day Earth, but they are found in great abundance on the surfaces of icy bodies in the outer Solar System, and as reddish aerosols in the atmospheres of outer Solar System planets and moons. In the presence of water, tholins could be raw materials for prebiotic chemistry (i.e., the non-livin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bishun Khare
Bishun Narain Khare (27 June 1933 – 20 August 2013) was a scientist who specialized in the chemistry of planetary atmospheres and of molecules relevant to biology. He published several papers on tholins, the organic molecules formed by ultraviolet radiation or cosmic rays. From 1968 to 1996, Khare worked in Carl Sagan's Laboratory for Planetary Studies at Cornell University. During this time he appeared in the ''Cosmos'' television series. From 1996 to 1998, he worked at the NASA Ames Research Center and from 1998 onward he worked at the SETI Institute. After his death, the International Astronomical Union named a crater on Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the S ... after him called the Khare Crater. Publications References/ External linksProfile on SETI [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miller–Urey Experiment
The Miller–Urey experiment (or Miller experiment) is a famous chemistry experiment that simulated the conditions thought at the time (1952) to be present in the atmosphere of the early, prebiotic Earth, in order to test the hypothesis of the chemical origin of life under those conditions. The experiment used water (H2O), methane (CH4), ammonia (NH3), hydrogen (H2), and an electric arc (the latter simulating hypothesized lightning). At the time, it supported Alexander Oparin's and J. B. S. Haldane's hypothesis that the hypothesized conditions on the primitive Earth favored chemical reactions that synthesized more complex organic compounds from simpler inorganic precursors. One of the most famous experiments of all time, it is considered to be groundbreaking, and to be the classic experiment investigating abiogenesis. It was performed in 1952 by Stanley Miller, supervised by Harold Urey at the University of Chicago, and published the following year. After Miller's death in 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abiogenesis
In biology, abiogenesis (from a- 'not' + Greek bios 'life' + genesis 'origin') or the origin of life is the natural process by which life has arisen from non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to living entities on Earth was not a single event, but an evolutionary process of increasing complexity that involved the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. Many proposals have been made for different stages of the process. The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It primarily uses tools from biology and chemistry, with more recent approaches attempting a synthesis of many sciences. Life functions through the specialized chemistry of carbon and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiolysis
Radiolysis is the dissociation of molecules by ionizing radiation. It is the cleavage of one or several chemical bonds resulting from exposure to high-energy flux. The radiation in this context is associated with ionizing radiation; radiolysis is therefore distinguished from, for example, photolysis of the Cl2 molecule into two Cl- radicals, where (ultraviolet or visible spectrum) light is used. For example, water dissociates under alpha radiation into a hydrogen radical and a hydroxyl radical, unlike ionization of water which produces a hydrogen ion and a hydroxide ion. The chemistry of concentrated solutions under ionizing radiation is extremely complex. Radiolysis can locally modify redox conditions, and therefore the speciation and the solubility of the compounds. Water decomposition Of all the radiation-based chemical reactions that have been studied, the most important is the decomposition of water. When exposed to radiation, water undergoes a breakdown sequence into hydrog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrolysis
The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''pyro'' "fire", "heat", "fever" and '' lysis'' "separating". Pyrolysis is most commonly used in the treatment of organic materials. It is one of the processes involved in charring wood.''Burning of wood'' , InnoFireWood's website. Accessed on 2010-02-06. In general, pyrolysis of organic substances produces volatile products and leaves , a carbon-rich solid residue. Extreme pyrolysis, which leaves mostly |
Alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloalkane by removal of a hydrogen atom from a Ring (chemistry), ring and has the general formula . Typically an alkyl is a part of a larger molecule. In structural formulae, the symbol R is used to designate a generic (unspecified) alkyl group. The smallest alkyl group is methyl, with the formula . Related concepts Alkylation is an important operation in refineries, for example in the production of high-octane gasoline. Alkylating antineoplastic agents are a class of compounds that are used to treat cancer. In such case, the term alkyl is used loosely. For example, nitrogen mustards are well-known alkylating agents, but they are not simple hydrocarbons. In chemistry, alkyl is a group, a substituent, that is attached to other molecular fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstellar Medium
In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. The interstellar medium is composed of multiple phases distinguished by whether matter is ionic, atomic, or molecular, and the temperature and density of the matter. The interstellar medium is composed, primarily, of hydrogen, followed by helium with trace amounts of carbon, oxygen, and nitrogen. The thermal pressures of these phases are in rough equilibrium with one another. Magnetic fields and turbulent motions also provide pressure in the ISM, and are typically more important, dynamically, than the thermal pressure is. In the interstellar medium, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation Of Tholins In Titan's Upper Atmosphere
Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary mineral deposit formed in a cave * Class formation, a topological group acting on a module satisfying certain conditions * Formation (group theory), a class of groups that is closed under some operations * Formation constant, an equilibrium constant for the formation of a complex in solution * Formation enthalpy, standard heat of formation of a compound * Formation (group theory), a class of groups * Formation (geology), a formally named rock stratum or geological unit * Formation of rocks, how rocks are formed * Formation and evolution of the Solar System, history of the Solar System * Rock formation, an isolated, scenic, or spectacular surface rock outcrop * Vegetation formation, a concept used to classify vegetation communities Militar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heteropolymer
In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are sometimes called ''bipolymers''. Those obtained from three and four monomers are called ''terpolymers'' and ''quaterpolymers'', respectively. Copolymers can be characterized by a variety of techniques such as NMR spectroscopy and size-exclusion chromatography to determine the molecular size, weight, properties, and composition of the material. Commercial copolymers include acrylonitrile butadiene styrene (ABS), styrene/butadiene co-polymer (SBR), nitrile rubber, styrene-acrylonitrile, styrene-isoprene-styrene (SIS) and ethylene-vinyl acetate, all of which are formed by chain-growth polymerization. Another production mechanism is step-growth polymerization, which is used to produce the nylon-12/6/66 copolymer of nylon 12, nylon 6 and nylo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carl Sagan
Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation. Sagan assembled the first physical messages sent into space, the Pioneer plaque and the Voyager Golden Record, universal messages that could potentially be understood by any extraterrestrial intelligence that might find them. Sagan argued the hypothesis, accepted since, that the high surface temperatures of Venus can be attributed to, and calculated using, the greenhouse effect.Extract of page 14 Initially an assistant professor at [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poly(acrylonitrile)
Poly, from the Greek πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its subsidiaries: ** Poly Property, a Hong Kong incorporated Chinese property developer ** Poly Real Estate, a Chinese real estate developer ** Poly Technologies, a defense manufacturing company * Poly (company), formerly Polycom, an American communications technology company People * Poly (footballer) (1906-1986), full name Policarpo Ribeiro de Oliveira, Brazilian footballer * Natasha Poly (born 1985), stage name of Russian supermodel Natalya Sergeyevna Polevshchikova * Poly Styrene (1957–2011), stage name of British musician Marianne Joan Elliott-Said Other uses * Hong Kong Polytechnic University, locally known as Poly * Poly (website), a website by Google * Polynesian, often shortened to poly, as in ‘Poly people are also called “Pasifika” or “Tangata Moana” (people of the ocean)’ * Polyamory, often shortened to poly, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
