wiktionary TOCright Turnover may refer to Business Turnover is sometimes a synonym for revenue or in certain contexts, sales , especially in European and South African usage. Services sold by a company during a particular period of time. Turnover is sometimes the name for a measure of how quickly Inventory High level inventory management inventory is sold. A high turnover means that goods are sold quickly, while a low turnover means that goods are sold more slowly. Asset turnover is a financial ratio that measures the efficiency of a company s use of its asset s in generating sales revenue or sales income to the company. ref cite book last Bodie first Zane coauthors Alex Kane and Alan J. Marcus title Essentials of Investments, 5th ed publisher McGraw Hill Irwin date 2004 isbn 0072510773 page 459 ref Turnover employment , relative rate at which an employer gains and loses staff, especially in North American usage Customer attrition Customer turnover , the rate at which a business loses customers, sometimes called the churn. Biology Cell turnover refers to the replacement of old cells with newly ... Giants season Turnover football , in American football occurs when the offense loses possession of the football because of a fumble, interception, or on downs Turnover basketball , a turnover in basketball ... without taking a shot Turnover rugby union , a turnover in rugby union occurs when a team loses possession in a ruck or a maul. Turnover rugby league , a turnover in rugby league occurs when a team loses possession or at the end of a team s six tackles. Demographics Population turnover, measures gross ... Turnover number , is the number of moles of substrate that a mole of catalyst can convert before ... converted by a mole of enzyme per second Music Turnover is a song by Fugazi from their album Repeater album Repeater Turn Over is a live album by Japanese band Show Ya Food Turnover food , a type of pastry or cake References Reflist Disambig ar cs Obrat da Turnover de Turnover ... more details
Refimprove date December 2009 Turnover number has two related meanings In enzymology , turnover number also termed k sub cat sub is defined as the maximum number of molecules of Substrate biochemistry substrate that an enzyme can convert to product per catalytic site per unit of time and can be calculated as follows k sub cat sub V sub max sub E sub T sub see Michaelis Menten kinetics . For example, carbonic anhydrase has a turnover number of 400,000 to 600,000 s sup 1 sup , which means that each carbonic anhydrase molecule can produce up to 600,000 molecules of product bicarbonate ions per second . ref name Hagen cite book author Hagen J title Industrial Catalysis A Practical Approach year 2006 publisher Wiley VCH location Weinheim, Germany ref In other chemical fields, such as organometallic chemistry organometallic catalysis , turnover number abbreviated TON is used with a slightly different meaning the number of moles of substrate that a mole of catalyst can convert before becoming inactivated. An ideal catalyst would have an infinite turnover number in this sense, because it wouldn t ever be consumed, but in actual practice one often sees turnover numbers which go from 100 to a million or more. The term turnover frequency abbreviated TOF is used to refer to the turnover per unit time, as in enzymology. For most relevant industrial applications, the turnover frequency is in the range ... 1 sup Turnover number of acetylcholinesterase Acetylcholinesterase AChE may be one of the fastest enzymes. It hydrolyzes acetylcholine to choline and an acetate group. One of the earliest values of the turnover ... sup min sup 1 sup . ref name Wilson cite journal author Wilson IB, Harrison MA title Turnover number .... ref name Berry cite journal author Berry WK title The turnover number of cholinesterase journal Biochem ... External links DEFAULTSORT Turnover Number Category Enzyme kinetics Category Chemical kinetics Category Units of catalytic activity Science stub de Wechselzahl nl Omzettingsgetal ja pl Liczba ... more details
distinguish Asymmetric catalytic oxidation Multiple issues context December 2009 wikify December 2009 Catalytic oxidation CO combines the production of random and honeycomb block catalyst s with fixed bed technology and integrated tube or plate heat exchanger s. It is used for destroying contaminants in the exhaust gases from industrial processes. ref http www.frtr.gov matrix2 section4 4 59.html ref References references DEFAULTSORT Catalytic Oxidation Category Catalysis ... more details
A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst ref Kinetics of catalytic reactions 2005 M. Albert Vannice ref . The catalytic cycle is the main method for describing the role of catalysts in biochemistry , organometallic chemistry , materials science, etc. Often such cycles show the conversion of a precatalyst to the catalyst. Since catalysts are regenerated, catalytic cycles are usually written as a sequence of chemical reactions in the form of a loop. In such loops, the initial step entails binding of one or more reactants by the catalyst, and the final step is the release of the product and regeneration of the catalyst. Articles on the Monsanto process , the Wacker process , and the Heck reaction show catalytic cycles. Image Catcycle.png thumb center 350px Catalytic cycle for conversion of A and B into C. A catalytic cycle is not necessarily a full reaction mechanism . For example, it may be that the intermediates have been detected, but it is not known by which mechanisms the actual elementary reactions occur. Sacrificial catalysts Often a so called sacrificial catalyst is also part of the reaction system with the purpose of regenerating the true catalyst in each cycle. As the name implies, the sacrificial catalyst is not regenerated and irreversibly consumed. This sacrificial compound is also known as a stoichiometric catalyst when added in Stoichiometry stoichiometric quantities compared to the main reactant . Usually the true catalyst is an expensive and complex molecule and added in quantities as small as possible. The stoichiometric catalyst on the other hand should be cheap and abundant. Citation needed date October 2007 This applies to the entire paragraph. References Reflist DEFAULTSORT Catalytic Cycle Category Reaction mechanisms Category Catalysis es Ciclo catal tico ja pt Ciclo catal tico fi Katalyyttinen sykli ... more details
A Catalytic receptor is an integral membrane protein possessing both Enzyme enzymatic catalysis catalytic and Receptor biochemistry receptor functions. ref name pmid17279064 cite journal author Alexander SP, Mathie A, Peters JA title Catalytic receptors journal Br. J. Pharmacol. volume 150 Suppl 1 issue pages S122 7 year 2007 month February pmid 17279064 pmc 2013840 doi 10.1038 sj.bjp.0707205 url issn ref The following is a list of the five major families of catalytic receptors class wikitable Family Member Gene Catalytic activity Endogenous Ligands Synthetic Ligands align center rowspan 4 align center Erb ref name ErbB family cite journal author Alexander SP, Mathie A, Peters JA title Catalytic receptors ErbB family journal Br. J. Pharmacol. volume 150 Suppl 1 issue pages S146 year 2007 month February doi 10.1038 sj.bjp.0706476 url issn ref ErbB1 epidermal growth factor receptor Gene EGFR tyrosine kinase EC number 2.7.10.1 Epidermal growth factor , amphiregulin , betacellulin , epigen , epiregulin , Heparin binding EGF like growth factor HB EGF , TGF alpha TGFa GW583340, gefitinib , erlotinib , tyrphostins AG879 and AG1478 align center HER2 neu ErbB2 Gene ERBB2 align center ERBB3 ErbB3 Gene ERBB3 Neuregulin 1 NRG 1 , NRG2 NRG 2 GW583340, gefitinib, erlotinib, tyrphostins AG879 and AG1478 align center Her 4 ErbB4 Gene ERBB4 Betacellulin, epiregulin, HB EGF, NRG 1, NRG 2, NRG 3, NRG ..., Mathie A, Peters JA title Catalytic receptors GDNF family journal Br. J. Pharmacol. volume 150 Suppl ... cite journal author Alexander SP, Mathie A, Peters JA title Catalytic receptors Natriuretic peptide ... JA title Catalytic receptors Neurotrophin family journal Br. J. Pharmacol. volume 150 Suppl 1 ... author Alexander SP, Mathie A, Peters JA title Catalytic receptors Toll like receptor family journal ... External links cite journal url http www.nature.com bjp journal vgrac ncurrent index.html Catalytic Receptors title Catalytic Receptors author authorlink coauthors date format work journal British Journal ... more details
Refimprove article date December 2007 File DodgeCatCon.jpg thumb right Catalytic converter on a 1996 Dodge Ram Van 2004 A catalytic converter colloquially, cat or catcon is a device used to reduce the array of emissions from an internal combustion engine . A catalytic converter works by using a catalyst ... oxides into less harmful gases. ref http www.ipa news.com en 89 0 Catalytic Converters.html Catalytic ... Environmental Protection Agency regulations on auto exhaust, catalytic converters are still most commonly used in automobile motor vehicle exhaust system s. Catalytic converters are also used on Electrical ... engine equipped machines. History The catalytic converter was invented by Eugene Houdry , a French mechanical engineer and expert in catalytic oil refining ref name Csere1988p63 Cite journal ... Catalyst, to develop catalytic converters for Petrol engine gasoline engines an idea ahead of its time ... Foundation . Retrieved January 7, 2011. ref The catalytic converter was further developed by John ... http www.nytimes.com 2008 11 15 us 15keith.html Carl D. Keith, a Father of the Catalytic Converter, Dies at 88 . The New York Times . November 15, 2008. ref creating the first production catalytic ... Image Pot catalytique vue de la structure.jpg thumb Ceramic core converter The catalytic converter ... honeycomb in modern catalytic converters, but stainless steel foil honeycombs are also used. The honeycomb ... dibenzodioxins dioxin . Types Two way A two way catalytic converter has two simultaneous ... 2x 2 sub 3x 1 2 O sub 2 sub xCO sub 2 sub x 1 H sub 2 sub O a combustion reaction This type of catalytic ... converters. Three way Since 1981, three way catalytic converters have been used in vehicle emission control systems in North America and many other countries on road going vehicles. A three way catalytic ... when the catalytic converter receives exhaust from an engine running slightly above the stoichiometric ... with 3 way catalytic converters are equipped with a Engine control unit computerized closed loop ... more details
Catalytic reforming is a chemical process used to convert petroleum refinery naphtha s, typically having ... . This process is quite different from and not to be confused with the catalytic steam reforming process ... other catalytic reforming processes that use methanol or biomass biomass derived feedstocks to produce ... Oil Products UOP , developed a catalytic reforming process using a catalyst containing platinum ... from the catalytic reforming process. To name a few of the other catalytic reforming versions that were ... version, designed for continuous catalyst regeneration, developed by UOP. Octanizing A catalytic reforming ... catalyst regeneration. Chemistry Before describing the reaction chemistry of the catalytic reforming process as used in petroleum refineries, the typical naphthas used as catalytic reforming ... catalytic hydrodesulfurizer to remove sulfur containing hydrocarbons and a catalytic ... to as straight run naphthas. It is the straight run heavy naphtha that is usually processed in a catalytic .... The table just below lists some fairly typical straight run heavy naphtha feedstocks, available for catalytic ... derived from the fluid catalytic cracking and Delayed coker coking processes used in many refineries ... naphthas. However, for the most part, catalytic reforming is mainly used on the straight run heavy naphthas ... chemistry There are a good many chemical reactions that occur in the catalytic reforming process, all ... the type or version of catalytic reforming used as well as the desired reaction severity, the reaction ... Administration ref The commonly used catalytic reforming catalysts contain noble metals such as platinum ... compounds. Therefore, the naphtha feedstock to a catalytic reformer is always pre processed in a hydrodesulfurization ... catalytic reforming reactions are ref name Gary cite book author Gary, J.H. and Handwerk, G.E. title ... of paraffins produce hydrogen. The overall net production of hydrogen in the catalytic reforming ... ref In many petroleum refineries, the net hydrogen produced in catalytic reforming supplies ... more details
A catalytic triad refers to the three amino acid residues found inside the active site of certain protease enzymes serine S , aspartate D , and histidine H . They work together to break peptide bonds on polypeptides . In general terms, catalytic triad can refer to any set of three residues that function together and are directly involved in catalysis . Because enzymes fold into complex three dimensional shapes, the residues of a catalytic triad can be far from each other in the primary structure however, they are brought close together in the tertiary structure the macromolecule macromolecular 3 dimensional unit. Example An example of a catalytic triad is present in chymotrypsin , wherein the triad on the enzyme consists of S195 that is, the serine found at residue 195 in the protein sequence , D102 and H57. In essence, S195 binds to the Substrate biochemistry substrate polypeptide to the side of a phenylalanine , tryptophan , or tyrosine residue closer to the C terminus , holding it in place. D102 and H57 then hydrolyze the bond. This takes place in several steps. Upon binding of the target protein, the carboxylic group COOH on D102 forms a low barrier hydrogen bond with H57, increasing the pKa of its imidazole nitrogen from 7 to about 12. This allows H57 to act as a powerful general base, and deprotonate S195. The deprotonated S195 serves as a nucleophile , attacking the carbonyl carbon on the C terminal side of the residue and forcing the carbonyl oxygen to accept an electron, and transforming the sp2 carbon into a tetrahedral intermediate. This intermediate is stabilized by an oxanion hole , which also involves S195. Collapse of this intermediate back to a carbonyl causes H57 to donate its proton to the nitrogen attached to the alpha carbon. The nitrogen and the attached peptide fragment c terminal to the F W or Y residue leave by diffusion. A water molecule then donates a proton to H57 and the remaining OH attacks the carbonyl carbon, forming another tetrahedral ... more details
Unreferenced date March 2008 Image Turnover 001.jpg thumb right 200px Sweet turnover made from puff pastry A turnover is a kind of pastry made by placing a filling on a piece of dough, folding the dough over, and sealing it. Turnovers can be sweet or savory and are often made as a sort of portable meal or dessert, similar to a sandwich . It is common for sweet turnovers to have a fruit filling and be made with a shortcrust pastry or puff pastry dough savory turnovers generally contain meat and or vegetables and can be made with any sort of dough, though a kneaded yeast dough seems to be the most common in Western cuisines. They are usually baking baked , but may be fried pie fried . Savory turnovers are often sold as convenience food s in supermarkets. Savory turnovers with meat or poultry and identified as a turnover for example, Beef Turnover or Cheesy Chicken Turnover have to meet a standard of identity or composition, and must contain a certain amount of meat or poultry. See also Calzone stromboli food Stromboli Panzerotti Hot Pockets Knish Jamaican patty Empanada Cornish pasty Sambusac Samosa Strudel Bridie Category Pies dessert stub pt Pastel culin ria fr Chausson aux pommes it Appelflap nl Appelflap ... more details
Citations missing date November 2009 A turnover tax is similar to a sales tax or a VAT , with the difference that it taxes intermediate and possibly capital goods. It is an indirect tax , typically on an ad valorem basis, applicable to a production process or stage. For example, when manufacturing activity is completed, a tax may be charged on some companies. Sales tax occurs when merchandise has been sold. See also Cascade tax Turnover tax in the Soviet Union DEFAULTSORT Turnover Tax Category Sales taxes lt Apyvartos mokestis zh ... more details
Refimprove date January 2009 In a human resources context, turnover or staff turnover or labor turnover ... long employees tend to stay or the rate of traffic through the revolving door. Turnover is measured ... a high turnover relative to its competitors, it means that employees of that company have a shorter average tenure than those of other companies in the same industry. High turnover can be harmful to a company ... total non farm seasonally adjusted monthly turnover rate was 3.3 . ref name jolt2008 cite web ... title Job Openings and Labor Turnover Survey publisher Bureau of Labor Statistics accessdate 2009 ... job sectors. For example, during the period 2001 2006, the annual turnover rate for all industry ... data.bls.gov cgi bin surveymost?jt Job Openings and Labor Turnover Survey ref during the same period ... , Series ID JTU70000000TSR, http data.bls.gov cgi bin surveymost?jt Job Openings and Labor Turnover ... turnover to for profit organizations has been estimated to be up to 150 of the employees remuneration ... overtime and low morale. In a healthcare context, staff turnover has been associated with worse ... and staff turnover affect outcomes in group CBT for persistent pain. Pain , 148 3 , 481 6 ref Internal vs. external turnover Like recruitment, turnover can be classified as internal or external . ref ... January first Allen M. last Ruby title Internal Teacher Turnover in Urban Middle School Reform volume 7 issue 4 pages 379 406 doi 10.1207 S15327671ESPR0704 2 ref Internal turnover involves employees ... disruption, or the Peter Principle effects of internal turnover exist, and therefore, it may be equally important to monitor this form of turnover as it is to monitor its external counterpart. Internal turnover might be moderated and controlled by typical HR mechanisms, such as an internal recruitment ... have high turnover, and employees can generally be replaced without the organization or business ... and lead to increased turnover as employees seek, and eventually find, more favorable employment ... more details
Accounting In accountancy accounting , the Inventory turnover is a measure of the number of times inventory is sold or used in a time period such as a year. The equation for inventory turnover equals the cost of goods sold divided by the average inventory . Inventory turnover is also known as inventory turns , stockturn , stock turns , turns , and stock turnover . Inventory Turnover Equation The formula for inventory turnover math mbox Inventory Turnover frac mbox Average Cost of Goods Sold mbox Average Inventory math The formula for average inventory math mbox Average Inventory frac mbox Beginning inventory Ending inventory mbox 2 math Alternatively, the average days to sell the inventory may also be calculated as follows ref Weygandt, J. J., Kieso, D. E., & Kell, W. G. 1996 . Accounting Principles 4th ed. . New York, Chichester, Brisbane, Toronto, Singapore John Wiley & Sons, Inc. p. 802. ref math mbox Average days to sell the inventory frac mbox 365 days mbox Inventory Turnover Ratio math Application in Business A low turnover rate may point to overstocking ref Commercial Loan Analysis principles and techniques for credit analysts and lenders By Kenneth R. Pirok ISBN 1557387168 ref ... rising prices or shortages. A high turnover rate may indicate inadequate inventory levels, which ... inventory is 9,000. The inventory turnover equals 7.37 times 70,000 9500 . Some compilers of industry ... yields a more realistic turnover ratio, but it is often necessary to use sales for purposes of comparative ... holding cost than one that turns over twice, or three times, or more in that time.Stock turnover also ..., chocolates, soft drinks so the stock turnover will be higher. However, a car dealer will have a low turnover due to the item being a slow moving item. As such only intra industry comparison will be appropriate ..., Chapter 7, 4, ISBN 0321277821 http www.kowboyz.nl blog mc44 inventory turnover Inventory Turnover Business Scenarios DEFAULTSORT Inventory Turnover Category Management accounting Category Financial ... more details
In basketball , a turnover occurs when a player from one team gives possession to a member of the opposing team by losing the ball. This can result from the ball being steal basketball stolen , the player making mistakes such as stepping out or throwing the ball out of bounds, or committing a violation such as traveling basketball traveling or committing an foul basketball offensive foul . Some players are prone to turnovers because of having poor court vision or making mental mistakes. Also, many superstars average more turnovers than anybody on their team as they will often be handling the ball. It is unusual for the best player of a team to have zero turnovers. Also, a point guard may often have the most turnovers because they are usually the player that possesses the ball most for their respective team. See also List of National Basketball Association career turnovers leaders Basketball statistics DEFAULTSORT Turnover Basketball Category Basketball terminology Category Basketball statistics de Turnover Basketball fr Turnover basket ball ru ... more details
Unreferenced date October 2006 Protein turnover also known as protein accretion is the balance between protein synthesis and Proteolysis protein degradation . More synthesis than breakdown indicates an anabolic state that builds lean tissues, more breakdown than synthesis indicates a catabolic state that burns lean tissues. Protein turnover is believed to decrease with age in all senescence organisms including humans. This results in an increase in the amount of damaged protein within the body. It is unknown if this is a cause or consequence of aging but it seems likely that it is in fact both. The damaged protein results in a slower protein turnover which then results in more damaged protein causing an exponential increase in damage to all protein within the body and to aging. Some bodybuilding supplement s claim to reduce the protein breakdown by reducing or blocking the number of catabolic hormones within the body. This is believed to increase anabolism. However if protein breakdown falls too low then the body would not be able to remove muscle cells that have been damaged during workouts which would in turn prevent the growth of new muscle cells. When older proteins are broken down in the body, they must be replaced. This concept is called protein turnover, and different types of proteins have very different turnover rates. Protein synthesis occurs during the process of Translation biology translation on ribosome s. Protein breakdown occurs generally in two cellular locations br lysosome Lysosomal protease s digest endocytosis endocytosed proteins br cytoplasm Cytoplasmic complexes, called proteasome s, digest older or abnormal proteins that have been tagged with ubiquitin for destruction. DEFAULTSORT Protein Turnover Category Protein biosynthesis Protein stub ... more details
Asset turnover is a financial ratio that measures the efficiency of a company s use of its asset s in generating sales revenue or sales income to the company. ref cite book last Bodie first Zane coauthors Alex Kane and Alan J. Marcus title Essentials of Investments, 5th ed publisher McGraw Hill Irwin date 2004 isbn 0072510773 page 459 ref math mbox Asset Turnover frac mbox Sales mbox Average Total Assets math Sales is the value of Net Sales or Sales from the company s income statement Average Total Assets is the average of the values of Total assets from the company s balance sheet in the beginning and the end of the fiscal period. References Reflist Category Financial ratios econometrics stub ja pl Wska nik rotacji maj tku ru vi S v ng quay t ng t i s n ... more details
The term Toarcian turnover, alternatively the Toarcian extinction, the Pliensbachian Toarcian extinction, or the Early Jurassic extinction, refers to the wave of extinctions that marked the end of the Pliensbachian stage and the start of the Toarcian stage of the Early Jurassic period, c. 183 million years ago. The Toarcian turnover was most strongly manifested in aquatic lifeforms, notably in mollusk groups like ammonites ref Wignall, Paul B., and Anthony Hallam. Mass Extinctions and Their Aftermath. Oxford, Oxford University Press, 1997 pp. 164 5. ref its reach was global in extent, as evidenced by research in Japanese waters, the Andean basin, and the floor of the former Tethys Sea . ref MacLeod, Kenneth G., and Christian Koeberl. Catastrophic Events and Mass Extinctions Impacts and Beyond. Boulder, CO, Geological Society of America, 2002 pp. 525 9. ref Evidence points to Hypoxia environmental anoxic bottom waters as the probable cause of these marine extinctions, linked in turn to the massive volcanism of the Karoo Ferrar eruptions in the relevant era. ref Marti, Joan, and Gerald Ernst. Volcanoes and the Environment. Cambridge, Cambridge University Press, 2005 p. 219. ref See also Anoxic event References reflist ExtEvent nav Category Extinction events Category Jurassic paleo stub geochronology stub eu Toarciar iraungitzea hu Pliensbachi toarci kihal si esem ny nn Den toarkiske omveltinga zh ... more details
In American football , a turnover on downs occurs when a team fails to convert a fourth down into a first down by gaining the required yardage. A team has four chances each chance is called a Down American football down to gain ten yard s or to score. Any ground gained during one down short of these ten yards is kept for the next chance. Thus, if a team gains four yards on first down, it then has three chances to gain the six remaining yards. If a team gains the required ten yards, it receives another four downs to gain another ten yards an event called a first down or cross the goal line for a score. Though teams have four chances, in most cases, only three are used. Usually, if a team fails to gain the needed yardage after the third down, it will then Punt football punt the ball, offering the opposing team possession, or attempt to kick a field goal football field goal if close enough. The opposing team will start their new set of downs to wherever the punt returner can advance the ball prior to being tackle American football tackled , or where the punt comes to rest, after rolling to a stop. But in some instances, a team may elect to use its fourth down to try to gain the yardage, rather than punt. This is often referred to as going for it or sticking as opposed to kicking . Factors that may lead to a team making this choice are Only a small distance is needed to gain a first down A team is close to, but not within field goal range The game s end is near, and if the team surrenders possession of the ball, they may not have another chance to score what is needed to win or tie the game. The game s end is near, and if the team is in field goal range but is trailing such that a field goal would not tie or win the game, but a touchdown would. Occasionally, a team trailing by exactly one field goal s points will elect to attempt a conversion if tying the game on a field goal ... of the ball, thus causing a turnover on downs. See also 1st & Ten graphics system 1st & Ten , the graphics ... more details
Synthetic Catalytic Scavenger is an artificial anti oxidant that has been demonstrated to extend cellular life. It was successful in C. elegans and in first promising trials in mice. Category Antioxidants Biology stub ... more details
A catalytic bead sensor is a type of sensor that is used for Gas detector gas detection . Principle File Sensor MSA 94150.jpg The catalytic bead sensor MSA 94150 thumb The catalytic bead sensor consist of two coils of fine platinum wire each embedded in a bead of alumina, connected electrically in a Wheatstone bridge circuit. One of the pellistor s is impregnated with a special catalyst which promotes oxidation whilst the other is treated to inhibit oxidation. Current is passed through the coils so that they reach a temperature at which oxidation of a gas readily occurs at the catalysed bead 500 550 C . Passing combustible gas raises the temperature further which increases the resistance of the platinum coil in the catalysed bead, leading to an imbalance of the bridge. This output change is linear, for most gases, up to and beyond 100 Explosive limit LEL , response time is a few seconds to detect alarm levels around 20 LEL ref http www.intlsensor.com pdf catalyticbead.pdf Catalytic bead sensor ref , at least 12 oxygen by volume is needed for the oxidation. Issues Catalyst poisoning because of the direct contact of the gas with the catalytic surface it may be deactivated in some circumstances. Sensor drift Decreased sensitivity may occur depending on operating and ambient conditions. Modes of failure which include poisoning and sinter blockage, they become apparent during routine maintenance checking. See also List of sensors References reflist Category Gas sensors ... more details
Primary sources date January 2008 Context date October 2009 Image Microlith screen.jpg thumb 100px left Close up of a Microlith screen Microlith is a brand of catalytic reactor constructed with a very thin substrate with short metal channels that resemble screens or meshes. Microlith reactors have low pressure drop, enabling design of a high cell density and low thermal mass, which simultaneously leads to a smaller, lighter and higher efficiency catalytic reactor. Both mass transfer and heat transfer are significantly increased by the design, allowing more rapid reactor response to gas temperatures as well as improved rates of reactant contact with the surface. The substrate is coated with a variety of materials including catalysts or adsorbent materials which provide a unique and superior approach to chemical reaction. Both mass transfer and heat transfer are significantly increased by the substrate design, allowing more rapid reactor response to gas temperatures as well as improved rates of reactant contact with the substrate surface. External links http www.precision combustion.com microlithreactor.html Microlith Reactor Systems http www.precision combustion.com 2003 01 1366 20Isooctane.pdf Performance of Microlith Based Catalytic Reactors for an Isooctane Reforming System tech stub Category Heating ... more details
Selective Non Catalytic Reduction SNCR is a method to lessen nitrogen oxide emissions in conventional power plants that burn biomass , incineration waste and coal . The process involves injecting either ammonia or urea into the firebox of the boiler at a location where the flue gas is between convert 760 and 1093 C F sigfig 2 lk on to react with the nitrogen oxides formed in the combustion process. The resulting product of the chemical redox reaction is elemental nitrogen N sub 2 sub , carbon dioxide CO sub 2 sub , and water H sub 2 sub O . Urea NH sub 2 sub CONH sub 2 sub is easier to handle and store than the more dangerous ammonia NH sub 3 sub . In the process it reacts like ammonia NH sub 2 sub CONH sub 2 sub H sub 2 sub O 2NH sub 3 sub CO sub 2 sub The reduction happens according to simplified ref Duo et al., 1992 Can. J. Chem. Engng, 70 , 1014 1020 ref 4 NO 4 NH sub 3 sub O sub 2 sub 4 N sub 2 sub 6 H sub 2 sub O The reaction mechanism itself involves NH sub 2 sub Radical chemistry radical s that attach to NO and then decompose. The reaction requires a certain temperature range to be effective, typically convert 760 to 1093 C F , otherwise the NO and the ammonia don t react. Ammonia that hasn t reacted is called ammonia slip and is undesirable, as the ammonia can react with other combustion species, such as sulfur trioxide SO sub 3 sub , to form ammonium ammonium salts . ref Cite book author The Babcock & Wilcox Company authorlink coauthors title Steam its generation and use ... near the walls slips through. Though in theory selective non catalytic reduction can achieve the same efficiency of about 90 as selective catalytic reduction selective catalytic reduction SCR .... However, selective non catalytic reduction has an economical advantage over selective catalytic reduction, as the cost of the catalyst isn t there. References reflist See also Selective catalytic reduction DEFAULTSORT Selective Non Catalytic Reduction Category NOx control de Selektive nicht katalytische ... more details
Asymmetric catalytic oxidation is a technique of oxidation oxidizing various substrate chemistry substrate s to give an enantiopure product using a catalyst . Reactions Jacobsen epoxidation of alkenes using manganese Salen ligand salen complex and sodium hypochlorite NaOCl Sharpless epoxidation of allyl alcohol s using titanium isopropoxide , diethyl tartrate , and t butyl hydroxyperoxide Sharpless asymmetric dihydroxylation of alkenes using dihydroquinine or dihydroquinidine ligands on an osmium metal center Sharpless oxyamination Shi epoxidation of alkenes using oxone and a fructose derived chiral catalyst Sulfonyloxaziridine enolate oxidation References Unreferenced date October 2007 references Chiral synthesis organic chem stub Category Catalysis es Oxidaci n asim trica catal tica ... more details
Catalytic chain transfer CCT is a process that can be incorporated into radical polymerization to obtain greater control over the resulting products. Introduction Radical polymerization of vinyl monomers, like Methyl methacrylate methyl metha acrylate of vinyl acetate is a common industrial method to prepare polymeric materials. One of the problems associated with this method is, however, that the radical polymerisation reaction rate is so high that even at short reaction times the polymeric chains are exceedingly long. This has several practical disadvantages, especially for polymer processing e.g. melt processing . A solution to this problem is catalytic chain transfer , which is a way to make shorter polymer chains in radical polymerisation processes. The method involves adding a catalytic chain transfer agent to the reaction mixture of the monomer and the radical initiator . Historical background Boris Smirnov and Alexander Marchenko USSR discovered in 1975 that cobalt porphyrin s are able to reduce the molecular weight of Poly methyl methacrylate PMMA formed during radical polymerization ... than the porphyrin catalysts and are the catalysts actually used commercially. Process File Catalytic ... Atom Transfer Radical Polymerization vs Catalytic Chain Transfer journal Macromolecules year 2003 ... doi 10.1021 cr9901236 author Gridnev, A. A. Steven Ittel Ittel, S. D. title Catalytic Chain Transfer ... 2 can become catalytic, and such catalytic chain transfer reactions are generally used to reduce the polymer molecular weight during the radical polymerization process. Mechanistically, catalytic ... pathways. ref name CCT0 5 The major products of catalytic chain transfer polymerization are vinyl terminated polymer chains. One of the major drawbacks of the process is that catalytic chain ... yields are obtained when using catalytic chain transfer agents during the polymerization of acrylate ... during these polymerization reactions. Utility The catalytic chain transfer process was commercialized ... more details
Asymmetric catalytic reduction is the use of various chiral catalyst s to reduction chemistry reduce a prochiral organic compound to obtain a chiral product. This is one of the several techniques used in chiral synthesis . Typically, a transition metal is used with a bulky chiral ligand to such that the substrate molecule can only approach in a particular orientation. This causes an external reductant to reduce the substrate in a predictable fashion. Well known examples include William Standish Knowles Knowles ruthenium based catalyst, similar to Wilkinson s catalyst , which reduces alkenes, and Noyori asymmetric hydrogenation catalysts using chiral BINAP ligands and dihydrogen to reduce ketones and alkenes. Transition metal free catalysts, i.e. organocatalyst s such as the CBS catalyst based on proline used to ketone s are known as well. References Unreferenced date October 2007 references Chiral synthesis Category Stereochemistry Category Catalysis organic chem stub ... more details
Receivable Turnover Ratio is one of the accounting activity ratios, a financial ratio . This ratio measures the number of times, on average, receivables e.g. Accounts Receivable are collected during the period. A popular variant of the receivables turnover ratio is to convert it into an Average Collection Period in terms of days. Remember that the Receivable turnover ratio is figured as turnover times and the Average collection period is in days . Sources Receivables Turnover Ratio Net receivable sales Average net receivables ref Weygandt, J. J., Kieso, D. E., & Kell, W. G. 1996 . Accounting Principles 4th ed. . New York, Chichester, Brisbane, Toronto, Singapore John Wiley & Sons, Inc. p. 800. ref Average Collection Period 365 Receivables Turnover Ratio ref Weygandt, J. J., Kieso, D. E., & Kell, W. G. 1996 . Accounting Principles 4th ed. . New York, Chichester, Brisbane, Toronto, Singapore John Wiley & Sons, Inc. p. 801. ref References references Category Financial ratios Finance stub vi S v ng quay kho n ph i thu ... more details
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