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solution to the foam surface. In this case, the following equation can be applied where a is the activity of the surfactant, R is the gas constant, and T is the absolute temperature: Γ 2 = − a R T ( ∂ γ ∂ a ) T {\displaystyle \Gamma _{2}=-{\frac {{a}\,}{RT}}\,\left({\frac {\partial \gamma }{\partial a}}\right)_{T}\,} I...	{ "page_id": 36052045, "title": "Continuous foam separation" }
=== Foam separation can be used for the extraction of proteins from a solution especially to concentrate the protein from a dilute solution. When purifying proteins from solution on an industrial scale, the most cost efficient method is desired. As such, foam separation offers a method with low capital and maintenance ...	{ "page_id": 36052045, "title": "Continuous foam separation" }
better the process is at recovering protein from solute into the foam state. Foam hydrodynamics as well as many of the variables that affect the success of foaming have limited understanding. This complicates using mathematical calculations to predict protein recovery by foaming. However some trends have been determine...	{ "page_id": 36052045, "title": "Continuous foam separation" }
However, in recent years foaming for protein and pharmaceutical extraction has gained increased interest for researchers. Purification of products is the most expensive part of product production in biotechnology, foaming offers an alternative method that is less expensive than some current techniques. == Separation eq...	{ "page_id": 36052045, "title": "Continuous foam separation" }
diagram, but can vary with placements and addition of equipment. === Design considerations === Additional equipment on the basic form of a foam separator apparatus can be used to achieve other desired effects that suit the type of application, but the underlying process of separation remains the same. The addition of e...	{ "page_id": 36052045, "title": "Continuous foam separation" }
in the percent removal of the surfactant. ==== Other ==== Some other factors that affect the effectiveness of foaming include the flow rate of the gas, the bubble size and distribution, the temperature of the solution, and the agitation of the solution. Detergents are known to affect foaming. They increase the ability ...	{ "page_id": 36052045, "title": "Continuous foam separation" }
The membrane theory of shells, or membrane theory for short, describes the mechanical properties of shells when twisting or under bending and assumes that bending moments are small enough to be negligible. The spectacular simplification of membrane theory makes possible the examination of a wide variety of shapes and s...	{ "page_id": 43457615, "title": "Membrane theory of shells" }
Nucleic acid sequence-based amplification, commonly referred to as NASBA, is a method in molecular biology which is used to produce multiple copies of single stranded RNA. NASBA is a two-step process that takes RNA and anneals specially designed primers, then utilizes an enzyme cocktail to amplify it. == Background == ...	{ "page_id": 9313361, "title": "NASBA (molecular biology)" }
single mixture at one temperature". Immediately after the invention of NASBA it was used for the rapid diagnosis and quantification of HIV-1 in patient sera. Although RNA can also be amplified by PCR using a reverse transcriptase (in order to synthesize a complementary DNA strand as a template), NASBA's main advantage ...	{ "page_id": 9313361, "title": "NASBA (molecular biology)" }
however, the second primer first binds to the (-)RNA The reverse transcriptase now produces a (+)cDNA/(-)RNA duplex. RNAse H again degrades the RNA and the first primer binds to the now single stranded +(cDNA) The reverse transcriptase now produces the complementary (-)DNA, creating a dsDNA duplex Exactly like step 6, ...	{ "page_id": 9313361, "title": "NASBA (molecular biology)" }
Bulging factor is an engineering term describing the geometry of out-of plane deformations of the surface of a crack on a pressurized fuselage structure. It is used in evaluating the damage tolerance of airframe fuselages. The single curved geometry and pressure differential causes a longitudinal crack to bulge out or ...	{ "page_id": 20978769, "title": "Bulging factor" }
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animal...	{ "page_id": 7251, "title": "Central nervous system" }
only central nervous tissue outside the meninges in direct contact with the environment, which opens up a pathway for therapeutic agents which cannot otherwise cross the meninges barrier. == Structure == The CNS consists of two major structures: the brain and spinal cord. The brain is encased in the skull, and protecte...	{ "page_id": 7251, "title": "Central nervous system" }
as well as midbrain and hindbrain) consists of a cortex, composed of neuron-bodies constituting gray matter, while internally there is more white matter that form tracts and commissures. Apart from cortical gray matter there is also subcortical gray matter making up a large number of different nuclei. === Spinal cord =...	{ "page_id": 7251, "title": "Central nervous system" }
nerves and the optic nerves are often considered structures of the CNS. This is because they do not synapse first on peripheral ganglia, but directly on CNS neurons. The olfactory epithelium is significant in that it consists of CNS tissue expressed in direct contact to the environment, allowing for administration of c...	{ "page_id": 7251, "title": "Central nervous system" }
and both cerebral hemispheres, among others. Additionally, parts of the visual and auditory systems are located in the midbrain, including control of automatic eye movements. The brainstem at large provides entry and exit to the brain for a number of pathways for motor and autonomic control of the face and neck through...	{ "page_id": 7251, "title": "Central nervous system" }
as a linkage between incoming pathways from the peripheral nervous system as well as the optical nerve (though it does not receive input from the olfactory nerve) to the cerebral hemispheres. Previously it was considered only a "relay station", but it is engaged in the sorting of information that will reach cerebral he...	{ "page_id": 7251, "title": "Central nervous system" }
voluntary movement. === Difference from the peripheral nervous system === The PNS consists of neurons, axons, and Schwann cells. Oligodendrocytes and Schwann cells have similar functions in the CNS and PNS, respectively. Both act to add myelin sheaths to the axons, which acts as a form of insulation allowing for better...	{ "page_id": 7251, "title": "Central nervous system" }
at the front, the mesencephalon, and, between the mesencephalon and the spinal cord, the rhombencephalon. (By six weeks in the human embryo) the prosencephalon then divides further into the telencephalon and diencephalon; and the rhombencephalon divides into the metencephalon and myelencephalon. The spinal cord is deri...	{ "page_id": 7251, "title": "Central nervous system" }
in the body, above the gut and notochord/spine. The basic pattern of the CNS is highly conserved throughout the different species of vertebrates and during evolution. The major trend that can be observed is towards a progressive telencephalisation: the telencephalon of reptiles is only an appendix to the large olfactor...	{ "page_id": 7251, "title": "Central nervous system" }
have a moderate degree of convolutions, and humans have quite extensive convolutions. Extreme convolution of the neocortex is found in dolphins, possibly related to their complex echolocation. == Clinical significance == === Diseases === There are many CNS diseases and conditions, including infections such as encephali...	{ "page_id": 7251, "title": "Central nervous system" }
The foot per second (plural feet per second) is a unit of both speed (scalar) and velocity (vector quantity, which includes direction). It expresses the distance in feet (ft) traveled or displaced, divided by the time in seconds (s). The corresponding unit in the International System of Units (SI) is the meter per seco...	{ "page_id": 2956372, "title": "Foot per second" }
Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multip...	{ "page_id": 1186904, "title": "Confocal microscopy" }
increased resolution is at the cost of decreased signal intensity – so long exposures are often required. To offset this drop in signal after the pinhole, the light intensity is detected by a sensitive detector, usually a photomultiplier tube (PMT) or avalanche photodiode, transforming the light signal into an electric...	{ "page_id": 1186904, "title": "Confocal microscopy" }
transgenic techniques can create organisms that produce their own fluorescent chimeric molecules (such as a fusion of GFP, green fluorescent protein with the protein of interest). Confocal microscopes work on the principle of point excitation in the specimen (diffraction limited spot) and point detection of the resulti...	{ "page_id": 1186904, "title": "Confocal microscopy" }
light blocked by the spinning-disk. Microlens enhanced confocal microscopes are therefore significantly more sensitive than standard spinning-disk systems. Yokogawa Electric invented this technology in 1992. Programmable array microscopes (PAM) use an electronically controlled spatial light modulator (SLM) that produce...	{ "page_id": 1186904, "title": "Confocal microscopy" }
advantage of not requiring a probe to be suspended nanometers from the surface, as in an AFM or STM, for example, where the image is obtained by scanning with a fine tip over a surface. The distance from the objective lens to the surface (called the working distance) is typically comparable to that of a conventional op...	{ "page_id": 1186904, "title": "Confocal microscopy" }
effect by using more sensitive photodetectors or by increasing the intensity of the illuminating laser point source. Increasing the intensity of illumination laser risks excessive bleaching or other damage to the specimen of interest, especially for experiments in which comparison of fluorescence brightness is required...	{ "page_id": 1186904, "title": "Confocal microscopy" }
quality and uniformity of the drug distribution. Confocal microscopy is also used to study biofilms — complex porous structures that are the preferred habitat of microorganisms. Some of temporal and spatial function of biofilms can be understood only by studying their structure on micro- and meso-scales. The study of m...	{ "page_id": 1186904, "title": "Confocal microscopy" }
The intersection of the two point spread functions gives a much smaller effective sample volume. From this evolved the single plane illumination microscope. Additionally deconvolution may be employed using an experimentally derived point spread function to remove the out of focus light, improving contrast in both the a...	{ "page_id": 1186904, "title": "Confocal microscopy" }
Science for spectrophotometry. The first confocal scanning microscope was built by Marvin Minsky in 1955 and a patent was filed in 1957. The scanning of the illumination point in the focal plane was achieved by moving the stage. No scientific publication was submitted and no images made with it were preserved. === The ...	{ "page_id": 1186904, "title": "Confocal microscopy" }
was a simple lens with a focal length of 8.5 mm. As opposed to all earlier and most later systems, the sample was scanned by movement of this lens (objective scanning), leading to a movement of the focal point. Reflected light came back to the semitransparent mirror, the transmitted part was focused by another lens on ...	{ "page_id": 1186904, "title": "Confocal microscopy" }
the first time. In 1978 and 1980, the Oxford-group around Colin Sheppard and Tony Wilson described a confocal microscope with epi-laser-illumination, stage scanning and photomultiplier tubes as detectors. The stage could move along the optical axis (z-axis), allowing optical serial sections. In 1979 Fred Brakenhoff and...	{ "page_id": 1186904, "title": "Confocal microscopy" }
finally sponsored development of a prototype. The design was acquired by Bio-Rad, amended with computer control and commercialized as 'MRC 500'. The successor MRC 600 was later the basis for the development of the first two-photon-fluorescent microscope developed 1990 at Cornell University. Developments at the KTH Roya...	{ "page_id": 1186904, "title": "Confocal microscopy" }
the light from a point excitation source using deep convolutional neural networks. == See also == Two-photon excitation microscopy == References == Hoffman, David P.; Shtengel, Gleb; Xu, C. Shan; Campbell, Kirby R.; Freeman, Melanie; Wang, Lei; Milkie, Daniel E.; Pasolli, H. Amalia; Iyer, Nirmala; Bogovic, John A.; Sta...	{ "page_id": 1186904, "title": "Confocal microscopy" }
Photosymbiosis is a type of symbiosis where one of the organisms is capable of photosynthesis. Examples of photosymbiotic relationships include those in lichens, plankton, ciliates, and many marine organisms including corals, fire corals, giant clams, and jellyfish. Photosymbiosis is important in the development, maint...	{ "page_id": 74062937, "title": "Photosymbiosis" }
can predominate over mycobiont preference. Phylogenetic analyses in lichenized fungi have suggested that, throughout evolutionary history, there has been repeated loss of photosymbionts, switching of photosymbionts, and independent lichenization events in previously unrelated fungal taxa. Loss of lichenization has like...	{ "page_id": 74062937, "title": "Photosymbiosis" }
coral fossil record, understanding the evolutionary history of the symbiosis is difficult. === Bilaterians === In basal bilaterians, photosymbiosis in marine or brackish systems is present only in the family Convolutidae. In the group Acoela there is limited knowledge on the symbionts present, and they have been vaguel...	{ "page_id": 74062937, "title": "Photosymbiosis" }
gastropods, heterobranch sea slugs, have two different systems for symbiosis. The first, Nudibranchia, acquire their symbionts through feeding on cnidarian prey that are in symbiotic relationships. In Nudibranchs, photosymbiosis has evolved twice, in Melibe and Aeolidida. In Aeolidida it is likely there have been sever...	{ "page_id": 74062937, "title": "Photosymbiosis" }
in open ocean communities. Photosynthetic plankton species associate with the symbiotes of dinoflagellates, diatoms, rhodophytes, chlorophytes, and cyanophytes that can be transferred both vertically and horizontally. In Foraminifera, benthic species will either have a symbiotic relationship with Symbiodinium or retain...	{ "page_id": 74062937, "title": "Photosymbiosis" }
Parker theorem, or the fundamental magnetostatic theorem, was formulated by physicist Eugene Parker in 1972. Parker's theorem describes how magnetic fields behave in perfectly conducting fluids, particularly in space plasmas. The theorem states that three-dimensional magnetic fields naturally form infinitesimally thin ...	{ "page_id": 78191707, "title": "Parker theorem" }
Nikolai Ivanovich Ivanov (Russian: Никола́й Ива́нович Ивано́в; April 8, 1836 – February 13, 1906) was a Russian businessman operating out of Tashkent, Russian Turkestan. He was known as the largest and most successful entrepreneur and commerce advisor in Tashkent, owning multiple distilleries and breweries in Tashkent ...	{ "page_id": 62331996, "title": "Nikolai Ivanov (entrepreneur)" }
production in Shymkent, as the city was near the Arys river valley, where santonin could be extracted naturally from plants. Ivanov built the Savinkov-Ivanov Chemical-Pharmaceutical Plant, and heavy equipment was carried from Altona, Hamburg to Shymkent through Orenburg on camel-drawn wagons with specially designed whe...	{ "page_id": 62331996, "title": "Nikolai Ivanov (entrepreneur)" }
Temple to Alexander Nevsky on the territory of the Botkin Cemetery is Ivanov's grave. == References ==	{ "page_id": 62331996, "title": "Nikolai Ivanov (entrepreneur)" }
Transposable elements (transposons, TEs, 'jumping genes') are short strands of repetitive DNA that can self-replicate and translocate within genomes of plants, animals, and prokaryotes, and they are generally perceived as parasitic in nature. Their transcription can lead to the production of dsRNAs (double-stranded RNA...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
indicating the rapid success of this class of transposon in the creation of hybrids, such as wheat, and peppermint and, in the distant past, maize. Plant hybridization often creates polyploids, with double, triple, quadruple or more the number of chromosomes present in the parent generation. Polyploid hybrids seem to b...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
process to unravel the strands involved, replicate the helitron, and subsequently ligate the replicated material into the new site. During this process, it is thought that the helitrons often encode for the surrounding DNA and integrate this into their own material. Non-autonomous helitrons may lack a transposase, a he...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
discovery, transposons can be difficult for the cellular machinery to detect. Many TEs contain stretches of genuine coding DNA, copied from the host, and there is no distinct structure, code, or identifying characteristic of any kind that would allow a cell to recognize the full range of transposable elements with accu...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
to histone modification and, if further epigenetic modification occurs, heterochromatin formation. This process is not well understood, as almost all information regarding it comes to us from the study of the FWA gene in Arabidopsis thaliana, a relatively TE-poor example in the plant kingdom. This paucity of informatio...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
certain allelic type that produces distinct morphological differences from the wild type. The predominant research into this subject has been conducted on Arabidopsis thaliana, which has the dual disadvantages of being both TE-poor and an overly genetically stable organism. The manner of formation of epialleles is some...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
siRNA or miRNA that stimulates in RNA-directed DNA methylation (RdDM) silencing of a similarly coded gene Insertion into a specific gene, interrupting its normal function Any one of these can have an extreme or minimal effect, depending on what systems the mutation affects. For example, if a transposon were to interrup...	{ "page_id": 42671200, "title": "Epigenetic regulation of transposable elements in the plant kingdom" }
The q-Gaussian is a probability distribution arising from the maximization of the Tsallis entropy under appropriate constraints. It is one example of a Tsallis distribution. The q-Gaussian is a generalization of the Gaussian in the same way that Tsallis entropy is a generalization of standard Boltzmann–Gibbs entropy or...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
= [ 1 + ( 1 − q ) x ] + 1 1 − q {\displaystyle e_{q}(x)=[1+(1-q)x]_{+}^{1 \over 1-q}} is the q-exponential and the normalization factor C q {\displaystyle C_{q}} is given by C q = 2 π Γ ( 1 1 − q ) ( 3 − q ) 1 − q Γ ( 3 − q 2 ( 1 − q ) ) for − ∞ < q < 1 {\displaystyle C_{q}={{2{\sqrt {\pi }}\Gamma \left({1 \over 1-q}\r...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
be used. For q < 1 {\displaystyle q<1} , F ( x ) = { 0 x < − 1 β ( 1 − q ) , 1 2 + 1 − q Γ ( 5 − 3 q 2 ( 1 − q ) ) x β 2 F 1 ( 1 2 , 1 q − 1 ; 3 2 ; − ( q − 1 ) β x 2 ) π Γ ( 2 − q 1 − q ) − 1 β ( 1 − q ) < x < 1 β ( 1 − q ) , 1 x > 1 β ( 1 − q ) . {\displaystyle F(x)={\begin{cases}0&x<-{\frac {1}{\sqrt {\beta (1-q)}}}...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
real values of ν. The scaled reparametrization introduces the alternative parameters q and β which are related to ν. Given a Student's t-distribution with ν degrees of freedom, the equivalent q-Gaussian has q = ν + 3 ν + 1 with β = 1 3 − q {\displaystyle q={\frac {\nu +3}{\nu +1}}{\text{ with }}\beta ={\frac {1}{3-q}}}...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
Box–Muller technique can generates pairs of q-Gaussian deviates that are not independent. In practice, only a single deviate will be generated from a pair of uniformly distributed variables. The following formula will generate deviates from a q-Gaussian with specified parameter q and β = 1 3 − q {\displaystyle \beta ={...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
entropy Tsallis distribution q-exponential distribution Q-Gaussian process == Notes == == Further reading == Juniper, J. (2007) "The Tsallis Distribution and Generalised Entropy: Prospects for Future Research into Decision-Making under Uncertainty" (PDF). Archived from the original (PDF) on 2011-07-06. Retrieved 2011-0...	{ "page_id": 32185446, "title": "Q-Gaussian distribution" }
Fibrinoid necrosis is a pathological lesion that affects blood vessels, and is characterized by the occurrence of endothelial damage, followed by leakage of plasma proteins, including fibrinogen, from the vessel lumen; these proteins infiltrate and deposit within the vessel walls, where fibrin polymerization subsequent...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
undergoing necrosis. A 2000 review stated that "whether the lesion is truly necrotic, in the sense that it reflects the result of unprogrammed cell death, has never been investigated in depth", and an electron microscopy study examining fibrinoid necrosis in rat models with induced pulmonary hypertension found that fib...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
term used to describe pathological changes in small arteries caused by a variety of conditions. Mislabeling lipohyalinosis as arteriolosclerosis overlooks the specific nature of lipohyalinosis as a condition involving fibrinoid necrosis (a particular form of vascular injury) and contributes to confusion. == Localizatio...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
is less pronounced than in PAN, despite both being forms of medium-sized vessel vasculitides. Systemic lupus erythematosus. Leucocytoclastic vasculitis. Systemic sclerosis, arthus reaction (a type III hypersensitivity reaction) and rheumatoid subcutaneous nodules. Malignant hypertension: Fibrinoid necrosis arises in th...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
the vascular endothelium. High blood pressure in malignant hypertension causes direct traumatic injury to the blood vessel wall, primarily due to increased tension, and mechanical stress on the arterial walls. Numerous studies have shown that sudden and substantial blood pressure elevations can induce fibrinoid changes...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
leads to ischemia and nerve damage, and ultimately gives rise to the clinical manifestations of neuropathy. ==== Hemorrhage ==== Whenever hypertension induces fibrinoid necrosis in the small cerebral arteries, this considerably raises the risk of intracerebral hemorrhage (ICH) due to two main factors: The deposition of...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
LCV from other similar conditions. Histopathologically, LCV is defined by the following key features: Neutrophilic infiltration in and around the vessel wall with leukocytoclasia. Fibrinoid necrosis. Vessel wall and tissue damage. The lack of fibrinoid necrosis and inflammatory infiltration in the vessel may preclude t...	{ "page_id": 1186919, "title": "Fibrinoid necrosis" }
The molecular formula C19H30O5 (molar mass: 338.43 g/mol) may refer to: Dodecyl gallate, Idebenone, a synthetic analog of coenzyme Q10 Piperonyl butoxide (PBO)	{ "page_id": 23993454, "title": "C19H30O5" }
Kentrophoros is a genus of ciliates in the class Karyorelictea. Ciliates in this genus lack a distinct oral apparatus and depend primarily on symbiotic bacteria for their nutrition. == Systematics == Kentrophoros is the sole genus in the family Kentrophoridae Jankowski 1980. The type species of the genus is K. fasciola...	{ "page_id": 54729846, "title": "Kentrophoros" }
capacity to fix CO2 autotrophically into biomass; instead they appear to be entirely heterotrophic. The ciliates ingest the bacteria as their primary food source. This symbiosis has therefore been called a "kitchen garden" carried by the ciliates to feed themselves. The symbionts occupy about 50% of the total volume. T...	{ "page_id": 54729846, "title": "Kentrophoros" }
The Plant Genomics and Phenomics Research Data Repository (PGP) is a data publication infrastructure to comprehensively publish multi-domain plant research data. It is hosted at the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) in Gatersleben, Germany. The repository hosts Digital Object Identifier ...	{ "page_id": 58858617, "title": "The Plant Phenomics and Genomics Research Data Repository" }
Institute of Plant Genetics and Crop Plant Research (IPK)	{ "page_id": 58858617, "title": "The Plant Phenomics and Genomics Research Data Repository" }
Acetylmethionine sulfoxide reductase may refer to: Methionine-S-oxide reductase L-methionine (S)-S-oxide reductase	{ "page_id": 38280313, "title": "Acetylmethionine sulfoxide reductase" }
The saxion is the scalar superpartner of the axion, and part of a chiral superfield. The axion represents the CP violating theory of the Standard Model. The axion and saxion are examples of the scalar boson class of particles with a very small mass, and a charge of 0.	{ "page_id": 39197820, "title": "Saxion" }
Emery's rule is the trend of social parasites to be parasites to species or genera they are closely related to. == History == In 1909, the Italian entomologist Carlo Emery noted that social parasites among insects (e.g., kleptoparasites) tend to be parasites of species or genera to which they are closely related. Over ...	{ "page_id": 4988029, "title": "Emery's rule" }
The Henry reaction is a classic carbon–carbon bond formation reaction in organic chemistry. Discovered in 1895 by the Belgian chemist Louis Henry (1834–1913), it is the combination of a nitroalkane and an aldehyde or ketone in the presence of a base to form β-nitro alcohols. This type of reaction is also referred to as...	{ "page_id": 2038911, "title": "Henry reaction" }
to the lack of a committed step in the reaction to form product. It is for this reason that research has been geared towards modifications to drive the reaction to completion. More information about this can be found in the modification section of this article. == Stereochemical Course == The figure below illustrates o...	{ "page_id": 2038911, "title": "Henry reaction" }
depiction of this coordination is illustrated above. == General Features == One of the many features of the Henry reaction that makes it synthetically attractive is that it utilizes only a catalytic amount of base to drive the reaction. Additionally a variety of bases can be used including ionic bases such as alkali me...	{ "page_id": 2038911, "title": "Henry reaction" }
addition to the previously mentioned modifications to the Henry reaction there are a variety of others. This includes the conversion of unreactive alkyl nitro compounds to their corresponding dianions which will react faster with carbonyl substrates, reactions can be accelerated using PAP as base, utilization of the re...	{ "page_id": 2038911, "title": "Henry reaction" }
== References == == External links == Media related to Henry reaction at Wikimedia Commons	{ "page_id": 2038911, "title": "Henry reaction" }
The International Academy of Mathematical Chemistry (IAMC) was founded in Dubrovnik, Croatia, in 2005 by Milan Randić. It is an organization for chemistry and mathematics avocation; its predecessors have been around since the 1930s. There are 88 Academy members (as of 2011) from around the world (27 countries), compris...	{ "page_id": 23534720, "title": "International Academy of Mathematical Chemistry" }
The Billion-Dollar Molecule is a book by journalist Barry Werth about the founding and early research efforts of the American biotechnology company Vertex Pharmaceuticals, which was founded in 1989 by Joshua Boger and was among the first biotechnology companies to adopt an explicit strategy of rational drug design as o...	{ "page_id": 10099846, "title": "The Billion-Dollar Molecule" }
A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those that include t...	{ "page_id": 7304, "title": "Coordination complex" }
one kind of a complex ion (or simply a complex), a species formed between a central metal ion and one or more surrounding ligands, molecules or ions that contain at least one lone pair of electrons. If all the ligands are monodentate, then the number of donor atoms equals the number of ligands. For example, the cobalt(...	{ "page_id": 7304, "title": "Coordination complex" }
compared his theoretical ammonia chains to hydrocarbons of the form (CH2)X. Following this theory, Danish scientist Sophus Mads Jørgensen made improvements to it. In his version of the theory, Jørgensen claimed that when a molecule dissociates in a solution there were two possible outcomes: the ions would bind via the ...	{ "page_id": 7304, "title": "Coordination complex" }
one electron, with the central atom providing the other electron, thus forming a regular covalent bond. The ligands are said to be coordinated to the atom. For alkenes, the pi bonds can coordinate to metal atoms. An example is ethylene in the complex [PtCl3(C2H4)]− (Zeise's salt). === Geometry === In coordination chemi...	{ "page_id": 7304, "title": "Coordination complex" }
ligands), where orbital overlap (between ligand and metal orbitals) and ligand-ligand repulsions tend to lead to certain regular geometries. The most observed geometries are listed below, but there are many cases that deviate from a regular geometry, e.g. due to the use of ligands of diverse types (which results in irr...	{ "page_id": 7304, "title": "Coordination complex" }
The arrangement of the ligands is fixed for a given complex, but in some cases it is mutable by a reaction that forms another stable isomer. There exist many kinds of isomerism in coordination complexes, just as in many other compounds. ==== Stereoisomerism ==== Stereoisomerism occurs with the same bonds in distinct or...	{ "page_id": 7304, "title": "Coordination complex" }
are themselves different. Four types of structural isomerism are recognized: ionisation isomerism, solvate or hydrate isomerism, linkage isomerism and coordination isomerism. Ionisation isomerism – the isomers give different ions in solution although they have the same composition. This type of isomerism occurs when th...	{ "page_id": 7304, "title": "Coordination complex" }
in a complex as ionic and assumes that the ligands can be approximated by negative point charges. More sophisticated models embrace covalency, and this approach is described by ligand field theory (LFT) and Molecular orbital theory (MO). Ligand field theory, introduced in 1935 and built from molecular orbital theory, c...	{ "page_id": 7304, "title": "Coordination complex" }
electronic spectroscopy; also known as UV-Vis. For simple compounds with high symmetry, the d–d transitions can be assigned using Tanabe–Sugano diagrams. These assignments are gaining increased support with computational chemistry. === Colors of lanthanide complexes === Superficially lanthanide complexes are similar to...	{ "page_id": 7304, "title": "Coordination complex" }
electrons and others with none. This effect is illustrated by the compounds TiX2[(CH3)2PCH2CH2P(CH3)2]2: when X = Cl, the complex is paramagnetic (high-spin configuration), whereas when X = CH3, it is diamagnetic (low-spin configuration). Ligands provide an important means of adjusting the ground state properties. In b...	{ "page_id": 7304, "title": "Coordination complex" }
state, absence of electrons in orbitals that are M–L antibonding, plus some "ligand field stabilization" associated with the d3 configuration. Associative processes Complexes that have unfilled or half-filled orbitals are often capable of reacting with substrates. Most substrates have a singlet ground-state; that is, t...	{ "page_id": 7304, "title": "Coordination complex" }
as phosphines, hydride, and CO. Example: (C5H5)Fe(CO)2CH3 Bioinorganic chemistry: Ligands are those provided by nature, especially including the side chains of amino acids, and many cofactors such as porphyrins. Example: hemoglobin contains heme, a porphyrin complex of iron Example: chlorophyll contains a porphyrin com...	{ "page_id": 7304, "title": "Coordination complex" }
o. This replaces the final 'e' when the anion ends with '-ide', '-ate' or '-ite', e.g. chloride becomes chlorido and sulfate becomes sulfato. Formerly, '-ide' was changed to '-o' (e.g. chloro and cyano), but this rule has been modified in the 2005 IUPAC recommendations and the correct forms for these ligands are now ch...	{ "page_id": 7304, "title": "Coordination complex" }
metal ions for ligands is described by a stability constant, also called the formation constant, and is represented by the symbol Kf. It is the equilibrium constant for its assembly from the constituent metal and ligands, and can be calculated accordingly, as in the following example for a simple case: xM (aq) + yL (aq...	{ "page_id": 7304, "title": "Coordination complex" }
solution. By Le Chatelier's principle, this causes the equilibrium reaction for the dissolving of the silver chloride, which has silver ion as a product, to shift to the right. This new solubility can be calculated given the values of Kf and Ksp for the original reactions. The solubility is found essentially by combini...	{ "page_id": 7304, "title": "Coordination complex" }
complex ions. Cyanide is used chiefly for extraction of gold and silver from their ores. Phthalocyanine complexes are an important class of pigments. === Analysis === At one time, coordination compounds were used to identify the presence of metals in a sample. Qualitative inorganic analysis has largely been superseded ...	{ "page_id": 7304, "title": "Coordination complex" }
Allopatric speciation (from Ancient Greek ἄλλος (állos) 'other' and πατρίς (patrís) 'fatherland') – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model: 86 – is a mode of speciation that occurs when biological populations become geographically isolated from each other...	{ "page_id": 334986, "title": "Allopatric speciation" }
to sympatry (speciation within the same area). Furthermore, the terms allopatric, vicariant, and geographical speciation are often used interchangeably in the scientific literature. This article will follow a similar theme, with the exception of special cases such as peripatric, centrifugal, among others. Observation o...	{ "page_id": 334986, "title": "Allopatric speciation" }
of rivers or bodies of water; glaciation; the formation or elimination of land bridges; the movement of continents over time (by tectonic plates); or island formation, including sky islands. Vicariant barriers can change the distribution of species populations. Suitable or unsuitable habitat may be come into existence,...	{ "page_id": 334986, "title": "Allopatric speciation" }
this too is debated. === Reproductive isolation === Reproductive isolation acts as the primary mechanism driving genetic divergence in allopatry and can be amplified by divergent selection. Pre-zygotic and post-zygotic isolation are often the most cited mechanisms for allopatric speciation, and as such, it is difficult...	{ "page_id": 334986, "title": "Allopatric speciation" }
arguments have been put forth that suggest the hybrids themselves can possibly become their own species: known as hybrid speciation. Reinforcement can play a role in all geographic modes (and other non-geographic modes) of speciation as long as gene flow is present and viable hybrids can be formed. The production of in...	{ "page_id": 334986, "title": "Allopatric speciation" }

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