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72-1167: ER-positive is one of the Receptor statuses identified in the classification of breast cancer . Receptor status was traditionally considered by reviewing each individual receptor ( ER , PR , her2 ) in turn, but newer approaches look at these together, along with the tumor grade , to categorize breast cancer into several conceptual molecular classes that have different prognoses and may have different responses to specific therapies. DNA microarrays have assisted this approach. Breast tumors that do not express ER, PR or Her2 are referred to as triple-negative breast cancers . Endocrine treatment may be beneficial for patients with hormone receptor positive breast tumors. There are two ways for treating these kind of tumors: http://www.breastcancer.org/treatment/hormonal/what_is_it/hormone_role.jsp Receptor (biochemistry) In biochemistry and pharmacology , receptors are chemical structures, composed of protein , that receive and transduce signals that may be integrated into biological systems. These signals are typically chemical messengers which bind to

144-404: A polysaccharide , and the light phase is generally Polyethylene glycol (PEG). Traditionally, the polysaccharide used is dextran . However, dextran is relatively expensive, and research has been exploring using less expensive polysaccharides to generate the heavy phase. If the target compound being separated is a protein or enzyme, it is possible to incorporate a ligand to the target into one of

216-402: A bound ligand is said to display "constitutive activity". The constitutive activity of a receptor may be blocked by an inverse agonist . The anti-obesity drugs rimonabant and taranabant are inverse agonists at the cannabinoid CB1 receptor and though they produced significant weight loss, both were withdrawn owing to a high incidence of depression and anxiety, which are believed to relate to

288-425: A complexing agent is present in the aqueous phase then it can lower the distribution ratio. For instance, in the case of iodine being distributed between water and an inert organic solvent such as carbon tetrachloride then the presence of iodide in the aqueous phase can alter the extraction chemistry: instead of D I + 2 {\displaystyle D_{\mathrm {I} ^{+2}}} being

360-410: A concentration or characteristics that it would damage the instrumentation or interfere with the analysis. If the sample can be extracted from the sorbent using a nonpolar solvent (such as toluene or carbon disulfide), and the coating is polar (such as HBr or phosphoric acid) the dissolved coating will partition into the aqueous phase. Clearly the reverse is true as well, using polar extraction solvent and

432-416: A constant it becomes This is because the iodine reacts with the iodide to form I 3 . The I 3 anion is an example of a polyhalide anion that is quite common. In a typical scenario, an industrial process will use an extraction step in which solutes are transferred from the aqueous phase to the organic phase; this is often followed by a scrubbing stage in which unwanted solutes are removed from

504-405: A direct organic extraction. The beans or leaves can be soaked in ethyl acetate which favorably dissolves the caffeine, leaving a majority of the coffee or tea flavor remaining in the initial sample. These are commonly used in industry for the processing of metals such as the lanthanides ; because the separation factors between the lanthanides are so small many extraction stages are needed. In

576-410: A mercury cathode to form sodium amalgam , while at an inert electrode (such as platinum) the sodium cations are not reduced. Instead, water is reduced to hydrogen. A detergent or fine solid can be used to stabilize an emulsion , or third phase . In solvent extraction, a distribution ratio (D) is often quoted as a measure of how well-extracted a species is. The distribution ratio is a measure of

648-516: A nonpolar diluent such as an alkane . A non- polar diluent favours the formation of uncharged non-polar metal complexes. Some extraction systems are able to extract metals by both the solvation and ion exchange mechanisms; an example of such a system is the americium (and lanthanide ) extraction from nitric acid by a combination of 6,6'- bis -(5,6-di pentyl -1,2,4-triazin-3-yl)- 2,2'-bipyridine and 2-bromo hexanoic acid in tert - butyl benzene . At both high- and low-nitric acid concentrations,

720-424: A nonpolar solvent to partition a nonpolar interferent. A small aliquot of the organic phase (or in the latter case, polar phase) can then be injected into the instrument for analysis. Amines (analogously to ammonia) have a lone pair of electrons on the nitrogen atom that can form a relatively weak bond to a hydrogen atom. It is therefore the case that under acidic conditions amines are typically protonated, carrying

792-557: A particular structure. This has been analogously compared to how locks will only accept specifically shaped keys . When a ligand binds to a corresponding receptor, it activates or inhibits the receptor's associated biochemical pathway, which may also be highly specialised. Receptor proteins can be also classified by the property of the ligands. Such classifications include chemoreceptors , mechanoreceptors , gravitropic receptors , photoreceptors , magnetoreceptors and gasoreceptors. The structures of receptors are very diverse and include

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864-429: A polymer–polymer system is often much more difficult than demixing a solvent extraction. Methods to improve the demixing include centrifugation , and application of an electric field . Polymer–salt systems. Aqueous two-phase systems can also be generated by generating the heavy phase with a concentrated salt solution. The polymer phase used is generally still PEG. Generally, a kosmotropic salt, such as Na 3 PO 4

936-502: A positive charge and under basic conditions they are typically deprotonated and neutral. Amines of sufficiently low molecular weight are rather polar and can form hydrogen bonds with water and therefore will readily dissolve in aqueous solutions. Deprotonated amines on the other hand, are neutral and have greasy , nonpolar organic substituents, and therefore have a higher affinity for nonpolar inorganic solvents. As such purification steps can be carried out where an aqueous solution of an amine

1008-415: A receptor and produce physiological responses such as change in the electrical activity of a cell . For example, GABA , an inhibitory neurotransmitter , inhibits electrical activity of neurons by binding to GABA A receptors . There are three main ways the action of the receptor can be classified: relay of signal, amplification, or integration. Relaying sends the signal onward, amplification increases

1080-410: A receptor is its binding affinity, which is inversely related to the dissociation constant K d . A good fit corresponds with high affinity and low K d . The final biological response (e.g. second messenger cascade , muscle-contraction), is only achieved after a significant number of receptors are activated. Affinity is a measure of the tendency of a ligand to bind to its receptor. Efficacy

1152-401: A sample is important for many modern biotechnology processes. However, samples often contain nucleases that degrade the target DNA before it can be purified. It has been shown that DNA fragments will partition into the light phase of a polymer–salt separation system. If ligands known to bind and deactivate nucleases are incorporated into the polymer phase, the nucleases will then partition into

1224-436: A similar complex to the uranium(VI), but it is possible to strip the plutonium in more than one way; a reducing agent that converts the plutonium to the trivalent oxidation state can be added. This oxidation state does not form a stable complex with TBP and nitrate unless the nitrate concentration is very high (circa 10 mol/L nitrate is required in the aqueous phase). Another method is to simply use dilute nitric acid as

1296-503: A single stage of extraction. A mixer settler consists of a first stage that mixes the phases together followed by a quiescent settling stage that allows the phases to separate by gravity. A novel settling device, Sudhin BioSettler, can separate an oil-water emulsion continuously at a much faster rate than simple gravity settlers. In this photo, an oil-water emulsion, stirred by an impeller in an external reservoir and pumped continuously into

1368-408: A stripping agent for the plutonium. This PUREX chemistry is a classic example of a solvation extraction . In this case, D U = k [TBP] [NO 3 ] . Another extraction mechanism is known as the ion exchange mechanism. Here, when an ion is transferred from the aqueous phase to the organic phase, another ion is transferred in the other direction to maintain the charge balance. This additional ion

1440-525: A suitable solvent. In that case, a soluble compound is separated from an insoluble compound or a complex matrix. From a hydrometallurgical perspective, solvent extraction is exclusively used in separation and purification of uranium and plutonium, zirconium and hafnium, separation of cobalt and nickel, separation and purification of rare earth elements etc., its greatest advantage being its ability to selectively separate out even very similar metals. One obtains high-purity single metal streams on 'stripping' out

1512-440: Is 100, then the silver/nickel separation factor (SF Ag/Ni ) is equal to D Ag /D Ni = SF Ag/Ni = 10. Success of liquid–liquid extraction is measured through separation factors and decontamination factors. The best way to understand the success of an extraction column is through the liquid–liquid equilibrium (LLE) data set. The data set can then be converted into a curve to determine the steady state partitioning behavior of

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1584-442: Is 43.8 kJ mol . Hence, if the aqueous phase in a reaction is a solution of sodium acetate while the organic phase is a nitrobenzene solution of benzyl chloride , then, when a phase transfer catalyst, the acetate anions can be transferred from the aqueous layer where they react with the benzyl chloride to form benzyl acetate and a chloride anion. The chloride anion is then transferred to the aqueous phase. The transfer energies of

1656-464: Is a locally acting feedback mechanism. The ligands for receptors are as diverse as their receptors. GPCRs (7TMs) are a particularly vast family, with at least 810 members. There are also LGICs for at least a dozen endogenous ligands, and many more receptors possible through different subunit compositions. Some common examples of ligands and receptors include: Some example ionotropic (LGIC) and metabotropic (specifically, GPCRs) receptors are shown in

1728-400: Is a method to separate compounds or metal complexes , based on their relative solubilities in two different immiscible liquids, usually water (polar) and an organic solvent (non-polar). There is a net transfer of one or more species from one liquid into another liquid phase, generally from aqueous to organic. The transfer is driven by chemical potential, i.e. once the transfer is complete,

1800-415: Is cheaper and can be done on a commercial scale. Often there are chemical species present or necessary at one stage of sample processing that will interfere with the analysis. For example, some air monitoring is performed by drawing air through a small glass tube filled with sorbent particles that have been coated with a chemical to stabilize or derivatize the analyte of interest. The coating may be of such

1872-446: Is commonly performed after a chemical reaction as part of the work-up , often including an acidic work-up. The term partitioning is commonly used to refer to the underlying chemical and physical processes involved in liquid–liquid extraction , but on another reading may be fully synonymous with it. The term solvent extraction can also refer to the separation of a substance from a mixture by preferentially dissolving that substance in

1944-483: Is extracting anisole from a mixture of water and 5% acetic acid using ether , then the anisole will enter the organic phase. The two phases would then be separated. The acetic acid can then be scrubbed (removed) from the organic phase by shaking the organic extract with sodium bicarbonate . The acetic acid reacts with the sodium bicarbonate to form sodium acetate , carbon dioxide , and water. Caffeine can also be extracted from coffee beans and tea leaves using

2016-405: Is important to investigate the rate at which the solute is transferred between the two phases, in some cases by an alteration of the contact time it is possible to alter the selectivity of the extraction. For instance, the extraction of palladium or nickel can be very slow because the rate of ligand exchange at these metal centers is much lower than the rates for iron or silver complexes. If

2088-469: Is independent of concentration. A classic example is the extraction of carboxylic acids ( HA ) into nonpolar media such as benzene . Here, it is often the case that the carboxylic acid will form a dimer in the organic layer so the distribution ratio will change as a function of the acid concentration (measured in either phase). For this case, the extraction constant k is described by k = [ HA organic ] /[ HA aqueous ] Using solvent extraction it

2160-429: Is neutralized with a base such as sodium hydroxide, then shaken in a separatory funnel with a nonpolar solvent that is immiscible with water. The organic phase is then drained off. Subsequent processing can recover the amine by techniques such as recrystallization, evaporation or distillation; subsequent extraction back to a polar phase can be performed by adding HCl and shaking again in a separatory funnel (at which point

2232-662: Is normally done on the industrial scale using machines that bring the two liquid phases into contact with each other. Such machines include centrifugal contactors , Thin Layer Extraction , spray columns , pulsed columns , and mixer-settlers . The extraction methods for a range of metals include: The extraction of cobalt from hydrochloric acid using Alamine 336 (tri-octyl/decyl amine) in meta - xylene . Cobalt can be extracted also using Ionquest 290 or Cyanex 272 { bis -(2,4,4-trimethylpentyl) phosphinic acid} . Copper can be extracted using hydroxy oximes as extractants,

Hormone receptor positive breast tumor - Misplaced Pages Continue

2304-436: Is not responding sufficiently to the hormone. The main receptors in the immune system are pattern recognition receptors (PRRs), toll-like receptors (TLRs), killer activated and killer inhibitor receptors (KARs and KIRs), complement receptors , Fc receptors , B cell receptors and T cell receptors . Liquid-liquid extraction Liquid–liquid extraction , also known as solvent extraction and partitioning ,

2376-408: Is often a hydrogen ion ; for ion exchange mechanisms, the distribution ratio is often a function of pH . An example of an ion exchange extraction would be the extraction of americium by a combination of terpyridine and a carboxylic acid in tert - butyl benzene . In this case Another example is the extraction of zinc , cadmium , or lead by a di alkyl phosphinic acid (R 2 PO 2 H) into

2448-417: Is possible in non-aqueous systems: In a system consisting of a molten metal in contact with molten salts , metals can be extracted from one phase to the other. This is related to a mercury electrode where a metal can be reduced, the metal will often then dissolve in the mercury to form an amalgam that modifies its electrochemistry greatly. For example, it is possible for sodium cations to be reduced at

2520-431: Is possible to extract uranium , plutonium , thorium and many rare earth elements from acid solutions in a selective way by using the right choice of organic extracting solvent and diluent. One solvent used for this purpose is the organophosphate tributyl phosphate (TBP). The PUREX process that is commonly used in nuclear reprocessing uses a mixture of tri-n-butyl phosphate and an inert hydrocarbon ( kerosene ),

2592-411: Is referred to as its endogenous ligand. E.g. the endogenous ligand for the nicotinic acetylcholine receptor is acetylcholine , but it can also be activated by nicotine and blocked by curare . Receptors of a particular type are linked to specific cellular biochemical pathways that correspond to the signal. While numerous receptors are found in most cells, each receptor will only bind with ligands of

2664-411: Is the measure of the bound ligand to activate its receptor. Not every ligand that binds to a receptor also activates that receptor. The following classes of ligands exist: Note that the idea of receptor agonism and antagonism only refers to the interaction between receptors and ligands and not to their biological effects. A receptor which is capable of producing a biological response in the absence of

2736-600: Is used, however PEG–NaCl systems have been documented when the salt concentration is high enough. Since polymer–salt systems demix readily they are easier to use. However, at high salt concentrations, proteins generally either denature, or precipitate from solution. Thus, polymer–salt systems are not as useful for purifying proteins. Ionic liquids systems. Ionic liquids are ionic compounds with low melting points. While they are not technically aqueous, recent research has experimented with using them in an extraction that does not use organic solvents. The ability to purify DNA from

2808-522: Is useful in extraction organic compounds such as organochloride and organophsophorus pesticides, as well as substituted benzene compounds from water samples. By mixing partially organic soluble samples in organic solvent (toluene, benzene, xylene), the organic soluble compounds will dissolve into the solvent and can be separated using a separatory funnel . This process is valuable in the extraction of proteins and specifically phosphoprotein and phosphopeptide phosphatases. Another example of this application

2880-435: The 'average' chemist is the use of a phase transfer catalyst . This is a charged species that transfers another ion to the organic phase. The ion reacts and then forms another ion, which is then transferred back to the aqueous phase. For instance, the 31.1 kJ mol is required to transfer an acetate anion into nitrobenzene, while the energy required to transfer a chloride anion from an aqueous phase to nitrobenzene

2952-422: The receptor theory of pharmacology stated that a drug's effect is directly proportional to the number of receptors that are occupied. Furthermore, a drug effect ceases as a drug-receptor complex dissociates. Ariëns & Stephenson introduced the terms "affinity" & "efficacy" to describe the action of ligands bound to receptors. In contrast to the accepted Occupation Theory , Rate Theory proposes that

Hormone receptor positive breast tumor - Misplaced Pages Continue

3024-443: The activation of receptors is directly proportional to the total number of encounters of a drug with its receptors per unit time. Pharmacological activity is directly proportional to the rates of dissociation and association, not the number of receptors occupied: As a drug approaches a receptor, the receptor alters the conformation of its binding site to produce drug—receptor complex. In some receptor systems (e.g. acetylcholine at

3096-428: The ammonium ion could be recovered by adding an insoluble counterion), or in either phase, reactions could be performed as part of a chemical synthesis. Temperature swing solvent extraction is an experimental technique for the desalination of drinking water. It has been used to remove up to 98.5% of the salt content in water, and is able to process hypersaline brines that cannot be desalinated using reverse osmosis. It

3168-427: The anions contribute to that given out by the reaction. A 43.8 to 31.1 kJ mol = 12.7 kJ mol of additional energy is given out by the reaction when compared with energy if the reaction had been done in nitrobenzene using one equivalent weight of a tetraalkylammonium acetate. Polymer–polymer systems. In a Polymer–polymer system, both phases are generated by a dissolved polymer. The heavy phase will generally be

3240-405: The cell, and include cytoplasmic receptors and nuclear receptors . A molecule that binds to a receptor is called a ligand and can be a protein, peptide (short protein), or another small molecule , such as a neurotransmitter , hormone , pharmaceutical drug, toxin, calcium ion or parts of the outside of a virus or microbe. An endogenously produced substance that binds to a particular receptor

3312-411: The cell. 4 examples of intracellular LGIC are shown below: Many genetic disorders involve hereditary defects in receptor genes. Often, it is hard to determine whether the receptor is nonfunctional or the hormone is produced at decreased level; this gives rise to the "pseudo-hypo-" group of endocrine disorders , where there appears to be a decreased hormonal level while in fact it is the receptor that

3384-440: The design of a good process, the distribution ratio should be not too high (>100) or too low (<0.1) in the extraction portion of the process. It is often the case that the process will have a section for scrubbing unwanted metals from the organic phase, and finally a stripping section to obtain the metal back from the organic phase. Battery of mixer-settlers counter currently interconnected. Each mixer-settler unit provides

3456-403: The dynamic behavior of receptors have been used to gain understanding of their mechanisms of action. Ligand binding is an equilibrium process. Ligands bind to receptors and dissociate from them according to the law of mass action in the following equation, for a ligand L and receptor, R. The brackets around chemical species denote their concentrations. One measure of how well a molecule fits

3528-399: The effect of a single ligand , and integration allows the signal to be incorporated into another biochemical pathway. Receptor proteins can be classified by their location. Cell surface receptors , also known as transmembrane receptors, include ligand-gated ion channels , G protein-coupled receptors , and enzyme-linked hormone receptors . Intracellular receptors are those found inside

3600-437: The extract phase containing the desired solute is separated out for further processing. A process used to extract small amounts of organic compounds from water samples. This process is done by injecting small amounts of an appropriate extraction solvent (C 2 Cl 4 ) and a disperser solvent (acetone) into the aqueous solution. The resulting solution is then centrifuged to separate the organic and aqueous layers. This process

3672-414: The following major categories, among others: Membrane receptors may be isolated from cell membranes by complex extraction procedures using solvents , detergents , and/or affinity purification . The structures and actions of receptors may be studied by using biophysical methods such as X-ray crystallography , NMR , circular dichroism , and dual polarisation interferometry . Computer simulations of

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3744-644: The heavy phase and be deactivated. Thus, this polymer–salt system is a useful tool for purifying DNA from a sample while simultaneously protecting it from nucleases. The PEG–NaCl system has been shown to be effective at partitioning small molecules, such as peptides and nucleic acids. These compounds are often flavorants or odorants. The system could then be used by the food industry to isolate or eliminate particular flavors. Caffeine extraction used to be done using liquid–liquid extraction, specifically direct and indirect liquid–liquid extraction (Swiss Water Method), but has since moved towards super-critical CO 2 as it

3816-577: The inhibition of the constitutive activity of the cannabinoid receptor. The GABA A receptor has constitutive activity and conducts some basal current in the absence of an agonist. This allows beta carboline to act as an inverse agonist and reduce the current below basal levels. Mutations in receptors that result in increased constitutive activity underlie some inherited diseases, such as precocious puberty (due to mutations in luteinizing hormone receptors) and hyperthyroidism (due to mutations in thyroid-stimulating hormone receptors). Early forms of

3888-410: The metal distribution ratio is higher than it is for an intermediate nitric acid concentration. It is possible by careful choice of counterion to extract a metal. For instance, if the nitrate concentration is high, it is possible to extract americium as an anionic nitrate complex if the mixture contains a lipophilic quaternary ammonium salt . An example that is more likely to be encountered by

3960-757: The metal value from the 'loaded' organic wherein one can precipitate or deposit the metal value. Stripping is the opposite of extraction: Transfer of mass from organic to aqueous phase. Liquid–liquid extraction is also widely used in the production of fine organic compounds , the processing of perfumes , the production of vegetable oils and biodiesel , and other industries. It is among the most common initial separation techniques, though some difficulties result in extracting out closely related functional groups. Liquid-Liquid extraction can be substantially accelerated in microfluidic devices, reducing extraction and separation times from minutes/hours to mere seconds compared to conventional extractors. Liquid–liquid extraction

4032-434: The more polar solvent, and the less polar solutes in the less polar solvent. In this experiment, the nonpolar halogens preferentially dissolve in the non-polar mineral oil. The separation factor is one distribution ratio divided by another; it is a measure of the ability of the system to separate two solutes. For instance, if the distribution ratio for nickel (D Ni ) is 10 and the distribution ratio for silver (D Ag )

4104-417: The multistage processes, the aqueous raffinate from one extraction unit is fed to the next unit as the aqueous feed, while the organic phase is moved in the opposite direction. Hence, in this way, even if the separation between two metals in each stage is small, the overall system can have a higher decontamination factor. Multistage countercurrent arrays have been used for the separation of lanthanides. For

4176-438: The need for a chemical reaction (see absorption ). This is the simplest type of solvent extraction. When a solvent is extracted, two immiscible liquids are shaken together. The more polar solutes dissolve preferentially in the more polar solvent, and the less polar solutes in the less polar solvent. Some solutes that do not at first sight appear to undergo a reaction during the extraction process do not have distribution ratio that

4248-472: The neuromuscular junction in smooth muscle), agonists are able to elicit maximal response at very low levels of receptor occupancy (<1%). Thus, that system has spare receptors or a receptor reserve. This arrangement produces an economy of neurotransmitter production and release. Cells can increase ( upregulate ) or decrease ( downregulate ) the number of receptors to a given hormone or neurotransmitter to alter their sensitivity to different molecules. This

4320-543: The organic phase, then a stripping stage in which the wanted solutes are removed from the organic phase. The organic phase may then be treated to make it ready for use again. After use, the organic phase may be subjected to a cleaning step to remove any degradation products; for instance, in PUREX plants, the used organic phase is washed with sodium carbonate solution to remove any dibutyl hydrogen phosphate or butyl dihydrogen phosphate that might be present. In order to calculate

4392-523: The outlet of the settling sections feed the inlets of the adjacent stage's mixing sections). Mixer-settlers are used when a process requires longer residence times and when the solutions are easily separated by gravity. They require a large facility footprint, but do not require much headspace, and need limited remote maintenance capability for occasional replacement of mixing motors. (Colven, 1956; Davidson, 1957) Centrifugal extractors mix and separate in one unit. Two liquids will be intensively mixed between

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4464-518: The overall system of chemical components that make up the solutes and the solvents are in a more stable configuration (lower free energy). The solvent that is enriched in solute(s) is called extract. The feed solution that is depleted in solute(s) is called the raffinate . Liquid–liquid extraction is a basic technique in chemical laboratories, where it is performed using a variety of apparatus, from separatory funnels to countercurrent distribution equipment called as mixer settlers . This type of process

4536-456: The phase equilibrium, it is necessary to use a thermodynamic model such as NRTL, UNIQUAC, etc. The corresponding parameters of these models can be obtained from literature (e.g. Dechema Chemistry Data Series, Dortmund Data Bank , etc.) or by a correlation process of experimental data. While solvent extraction is often done on a small scale by synthetic lab chemists using a separatory funnel , Craig apparatus or membrane-based techniques, it

4608-437: The polymer phases. This improves the target's affinity to that phase, and improves its ability to partition from one phase into the other. This, as well as the absence of solvents or other denaturing agents, makes polymer–polymer extractions an attractive option for purifying proteins. The two phases of a polymer–polymer system often have very similar densities, and very low surface tension between them. Because of this, demixing

4680-432: The solute between the two phases. The y-axis is the concentration of solute in the extract (solvent) phase, and the x-axis is the concentration of the solute in the raffinate phase. From here, one can determine steps for optimization of the process. This is commonly used on the small scale in chemical labs. It is normal to use a separating funnel . Processes include DLLME and direct organic extraction. After equilibration,

4752-561: The solute exists in more than one chemical form in either phase, then K d and D usually have different values. Depending on the system, the distribution ratio can be a function of temperature, the concentration of chemical species in the system, and a large number of other parameters. Note that D is related to the Gibbs Free Energy (Δ G) of the extraction process. In solvent extraction, two immiscible liquids are shaken together. The more polar solutes dissolve preferentially in

4824-528: The spinning rotor and the stationary housing at speeds up to 6000 RPM. This develops great surfaces for an ideal mass transfer from the aqueous phase into the organic phase. At 200–2000 g, both phases will be separated again. Centrifugal extractors minimize the solvent in the process, optimize the product load in the solvent and extract the aqueous phase completely. Counter current and cross current extractions are easily established. Some solutes such as noble gases can be extracted from one phase to another without

4896-597: The table below. The chief neurotransmitters are glutamate and GABA; other neurotransmitters are neuromodulatory . This list is by no means exhaustive. Enzyme linked receptors include Receptor tyrosine kinases (RTKs), serine/threonine-specific protein kinase, as in bone morphogenetic protein and guanylate cyclase, as in atrial natriuretic factor receptor. Of the RTKs, 20 classes have been identified, with 58 different RTKs as members. Some examples are shown below: Receptors may be classed based on their mechanism or on their position in

4968-427: The total concentration of a solute in the organic phase divided by its concentration in the aqueous phase . The partition or distribution coefficient (K d ) is the ration of solute concentration in each layer upon reaching equilibrium. This distinction between D and K d is important. The partition coefficient is a thermodynamic equilibrium constant and has a fixed value for the solute’s partitioning between

5040-420: The two bottom side ports of BioSettler, is separated very quickly into a clear organic (mineral oil) layer exiting via the top of BioSettler and an aqueous (coloured with a red food dye) layer being pumped out continuously from the bottom of BioSettler. In the multistage countercurrent process, multiple mixer settlers are installed with mixing and settling chambers located at alternating ends for each stage (since

5112-427: The two phases. The distribution ratio’s value, however, changes with solution conditions if the relative amounts of A and B change. If we know the solute’s equilibrium reactions within each phase and between the two phases, we can derive an algebraic relationship between K d and D . The partition coefficient and the distribution ratio are identical if the solute has only one chemical form in each phase; however, if

5184-466: The uranium(VI) are extracted from strong nitric acid and are back-extracted (stripped) using weak nitric acid. An organic soluble uranium complex [UO 2 (TBP) 2 (NO 3 ) 2 ] is formed, then the organic layer bearing the uranium is brought into contact with a dilute nitric acid solution; the equilibrium is shifted away from the organic soluble uranium complex and towards the free TBP and uranyl nitrate in dilute nitric acid. The plutonium(IV) forms

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