environmentaldegradation as The reduction of the capacity of the environment to meet social and ecological ... 2010 06 09 date 2004 03 31 ref Environmentaldegradation is of many types. When natural habitats are destroyed or natural resources are depleted, environment is degraded. Environmental Change ... Population growth and environmentaldegradation http www.blackwell synergy.com links doi 10.1111 0004 5608.00156 abs Annals of the Association of American Geographers Environmental Change in the Kalahari Integrated Land Degradation Studies for Nonequilibrium Dryland Environments http meta2.com PDB Weekly PDBEnvironmentalDegradation.pdf Public Daily Brief Threat EnvironmentalDegradation http www.ourplanet.com imgversn 95 roberts.html Focus Environmentaldegradation is contributing to health threats worldwide http www.tms.org Meetings Specialty ED2005 home.html EnvironmentalDegradation of Materials ... EnvironmentalDegradation Index by Jha & Murthy for 174 countries Category Environmental issues Category Environmental science ar ca Impacte ambiental es Impacto ambiental gl Impacto ambiental ... , acute respiratory infection s or diarrhea illnesses that are largely preventable. See also Environmental ... more details
wiktionarypar degradationDegradation may refer to Biodegradation , the processes by which organic substances are broken down by living organisms Chemical decomposition , the degradation of chemical compounds Degradation song , by the Violent Femmes Degradation telecommunications , the loss of quality of an electronic signal Cashiering or degradation ceremony, a ritual performed when cleric is deprived of office or a Knight is stripped of the honour Elegant degradation , in engineering, the gradual failing of a machine Graceful degradationEnvironmentaldegradation , in ecology , damage to the ecosystem and loss of biodiversity disambig cs Degradace de Degradation fr D gradation id Degradasi it Degradazione pl Degradacja sk Degrad cia ... more details
In telecommunication , degradation , which may be categorized as either graceful degradation graceful or catastrophic , has the following meanings The deterioration in quality, level, or standard of performance of a functional unit . In telecommunication communications , a condition in which one or more of the required performance parameters fall outside predetermined limits, resulting in a lower quality of service . There are several forms and causes of degradation in electric signals, both in the time domain and in the physical domain, including runt pulse , Voltage spike , jitter , wander , swim, Drift telecommunication drift , glitch , ringing signal ringing , crosstalk , antenna effect not the same antenna effect as in IC manufacturing , and phase noise . Degradation usually refers to reduction in quality of an analog or digital signal. When a signal is being transmitted or received, it undergoes changes which are undesirable. These changes are called degradation. Degradation is usually caused by Weather or environmental conditions. Terrain Other signals. Faulty or poor quality equipments. 1. Degradation by weather conditions A signal has two important factors a Frequency b Wavelength. If weather is fine & temperature is normal, the signal can be transmitted within given frequency & wavelength limits. The signal travels with velocity c 3 10 sup 8 sup m s, which is equal to speed of light. For frequency f Hz & wavelength m, we have f c . So, when weather conditions detoriate, frequency f has to be increased. This causes the wavelength to decrease, which means that the signal travels lesser distance now. FS1037C electronics stub Category Digital electronics Category Fault tolerance Category Noise Category Telecommunications terms ... more details
Sustainable agriculture Environmental impact of irrigation col2 Desertification Soil Degradation Soil degradation References reflist 2 Further reading cite web title Human Induced Land Degradation ...File Karst following phosphate mining on Nauru.jpg thumb Serious land degradation in Nauru after the depletion of the phosphate cover through mining Land degradation is a concept in which the value of the biophysical environment is affected by one or more combination of human induced processes acting upon the land. ref name rural cite book title Rural Land Degradation in Australia last Conacher first ... Nelson. 1997. Meanings of environmental terms. Journal of Environmental Quality 26 581 589. ref Natural ... Overgrazing by livestock can lead to land degradation Land degradation is a global problem, largely ... Environmental Impacts of Irrigation Projects a Review series In Annual Report 1988 of the International ... Pullman, Washington Pullman , USA. The main outcome of land degradation is a substantial reduction ... cause land degradation include shifting cultivation without adequate fallow periods, absence of soil .... The role of population factors in land degradation processes obviously occurs in the context of the underlying ... multiple crops by irrigating unsuitable soils. Severe land degradation affects a significant ... land degradation from seawater inundation , particularly in river delta s and on low lying islands ... 2001 title Land degradation an overview booktitle Responses to Land Degradation. Proc. 2nd. International Conference on Land Degradation and Desertification publisher Oxford Press location New Delhi, India url http soils.usda.gov use worldsoils papers land degradation overview.html accessdate 2006 06 20 D.L. Johnson and L.A. Lewis Land Degradation Creation and Destruction , 2nd edition, Rowman and Littlefield, Lanham, Boulder, New York, Toronto, Oxford, 2007. DEFAULTSORT Land Degradation Category Environmental soil science Category Environmental issues Category Physical geography ar ... more details
. Degradation can be useful for recycling reusing the polymer waste to prevent or reduce environmental pollution . Degradation can also be induced deliberately to assist structure determination . Polymeric ...Polymer degradation is a change in the properties tensile strength , colour , shape, etc. of a polymer or polymer based product under the influence of one or more environmental factors such as heat , light ... and plastics encountered in daily life. Each of these polymers has its own characteristic modes of degradation ... 200px Close up of broken fuel pipe connector Photoinduced degradation main UV degradation Most polymers ... ray s are usually involved in such reactions. Thermal degradation main Thermal degradation ... and water. The degradation takes place by class wikitable Thermolysis type Added material Temperature ... dioxide and hydrogen Chemical degradation main Chemically Assisted Degradation of Polymers Solvolysis .... Nylon Polyamide is sensitive to degradation by acids and polyamide mouldings will crack when attacked ... to degradation. Ozone cracks form in products under tension, but the critical strain is very small ... IR spectrum showing carbonyl absorption due to oxidative degradation of polypropylene crutch moulding ... start to grow in the regions affected. Galvanic action Polymer degradation by galvanic action was first ... that plastics can corrode , i.e. polymer degradation may occur through galvanic action similar ... polyimide s, triazine s, and blends thereof. Degradation occurs in the form of dissolved resin and loose ... structure. Standard corrosion protection procedures were found to prevent polymer degradation ... elsewhere in the world. Biological degradation main Synthetic biodegradable polymer Biodegradable ... site where degradation is very difficult due to the lack of oxygen and moisture. Stabilisers ... of crosslinking of the polymers and degradation the property of polymers. See also Applied spectroscopy Forensic engineering Forensic materials engineering Forensic polymer engineering Environmental ... more details
The Weerman degradation is an organic reaction in carbohydrate chemistry in which an aldonamide derived from an aldonic acid is degraded by sodium hypochlorite forming a new sugar with one less carbon. The reaction is named after R.A. Weerman ref R. A. Weerman, Rec. Trav. Chim., 37, 16 1917 . ref The reaction mechanism is that of the related Hofmann degradation . One study demonstrated the direct oxidation of glucose to arabinose by the same sodium hypochlorite skipping the aldonic acid and aldoamide steps. ref cite doi 10.1021 ja01528a042 ref References Reflist See also Curtius rearrangement Hofmann degradation Ruff Fenton degradation Wohl degradation Category Rearrangement reactions Category Carbohydrates Category Degradation reactions Category Name reactions zh Weerman ... more details
The Bergmann degradation is a series of chemical reaction s designed to remove a single amino acid from the carboxylic acid end of a peptide . ref Bergmann, M. Science 1934 , 79 , 439. ref ref Bergmann, M. Zervas, L. J. Biol. Chem. 1936 , 113 , 341. ref Image Bergmann Degradation Reaction Scheme.png center 600px The Bergmann degradation The acyl azide of a peptide 1 undergoes a Curtius rearrangement in the presence of benzyl alcohol 2 to give a Carboxybenzyl benzyl carbamate 3 . The Cbz group of intermediate 3 is removed by hydrogenolysis to give an unsubstituted amide 4 and an aldehyde 5 . References Reflist See also Curtius rearrangement Edman degradation reaction stub Category Organic redox reactions Category Rearrangement reactions Category Degradation reactions Category Name reactions es Degradaci n de Bergmann zh Bergmann ... more details
Orphan date October 2008 File LogP200.jpg right 200px thumb Flow reaction system for automated forced degradation testing Forced degradation or accelerated degradation is a process whereby the natural degradation rate of a product or material is increased by the application of an additional stress. Introduction Forced degradation studies are used to identify reactions which may occur to degrade a processed product. Usually conducted before final formulation, forced degradation uses external stresses to rapidly screen material stabilities. Longer term storage tests are usually used to measure similar properties when final formulations are involved because of the stringent FDA regulations. These tests are generally more expensive because of the time involved than forced degradation which is therefore used for rapid selection and elimination tests. Common stresses There are a number of common stresses which are used to pH acid base Chemical processes are often catalysed by the presence of acids and bases. The exposure of materials to these can therefore accelerate degradation reactions. Temperature In accordance to Arrhenius equation arrhenius kinetics , increasing temperature increases the rate of any degradation process. Temperature is often used in conjunction with other stresses to increase reaction rates. Oxidation Concentration Light Methodologies Standard methodologies include Wet chemistry methods Flow chemistry Calorimetry HPLC Application Empty section date July 2010 See also Chemical decomposition Thermogravimetric analysis Total productive maintenance External links http www.syrris.com Degradation.aspx Flow chemistry degradation by Syrris Category Chemical engineering ... more details
Unreferenced date December 2009 Elegant degradation is a term used in engineering to describe what occurs to machines which are subject to constant, repetitive stress. Externally, such a machine maintains the same appearance to the user, appearing to function properly. Internally, the machine slowly weakens over time. Eventually, unable to withstand the stress, it breaks down. Compared to Fault tolerant system graceful degradation , the operational quality does not decrease at all, but the breakdown may be just as sudden. This term s meaning varies depending on context and field, and may not be strictly considered exclusive to engineering. ie. if someone knows of different uses, please add them here and possibly other pages See also Fail safe Fail safe Fail soft Category Engineering Category Fault tolerance DEFAULTSORT Elegant Degradation Tech stub ... more details
The Emde degradation also called Emde reaction or Emde reduction is a method for the Redox reduction of a quaternary ammonium cation to a tertiary amine with sodium amalgam ref H. Emde. Ber deutsch chem Ges 42 1909 p2590 ref ref W P tsch. Lexikon bedeutender Chemiker VEB Bibliographisches Institut Leipzig, 1989 ISBN 3817110553 ref ref M B Smith, J March. March s Advanced Organic Chemistry Wiley, 2001 ISBN 0 471 58589 0 ref Image 500px Emderxn.png center 500px Emde degradation This organic reaction was first described in 1909 by the German chemist Hermann Emde and was for a long time of great importance in structure elucidation of many alkaloid s, for example that of ephedrine . Alternative reducing agent s exist for this reaction for instance, lithium aluminium hydride . See also Related reactions are the Hofmann elimination and the Von Braun reaction References references DEFAULTSORT Emde Degradation Category Organic redox reactions Category Name reactions Category Degradation reactions nl Emde degradatie ja zh Emde ... more details
In geology , degradation refers to the lowering of a fluvial surface, such as a stream bed or floodplain , through Erosion erosional processes . ref cite web url http www.esc.nsw.gov.au site Landcare 2 3.asp title Estuarine & Floodplain degradation publisher Eurobodalla Landcare accessdate 2009 08 31 Dead link date October 2010 bot H3llBot ref ref cite journal doi 10.1029 WR019i005p01057 title Causes of River Bed Degradation year 1983 author Galay, V. J. journal Water Resources Research volume 19 pages 1057 ref It is the opposite of aggradation . Degradation is characteristic of channel networks in which either bedrock erosion is taking place, or in systems that are sediment starved and are therefore entraining more material than is being deposited. When a stream degrades, it leaves behind a fluvial terrace . This can be further classified as a strath terrace a bedrock terrace that may have a thin mantle of alluvium if the river is incising through bedrock. These terraces may often be dated with methods such as cosmogenic radionuclide dating , OSL dating , and Geomagnetic reversal Geomagnetic polarity time scale paleomagnetic dating using reversals in the Earth s magnetic field to constrain the timing of events to find when a river was at a particular level and how quickly it is downcutting. References references cite journal doi 10.1061 ASCE 0733 9429 1986 112 6 497 title Simulation of Missouri River Bed Degradation year 1986 author Holly, Forrest M. journal Journal of Hydraulic Engineering volume 112 pages 497 last2 Karim first2 M. Fazle cite journal doi 10.2110 jsr.2005.029 title Discontinuity Bounded Alluvial Sequences of the Southern Gangetic Plains, India Aggradation and Degradation in Response to Monsoonal Strength year 2005 author Gibling, M.R. journal Journal of Sedimentary Research volume 75 pages 369 River morphology geology stub geo term stub Category geological processes Category Sedimentology Category Geomorphology Category Fluvial landforms Category Water ... more details
. Polymers which possess UV absorbing groups such as aromatic ring s may also be sensitive to UV degradation ... carbonyl absorption due to UV degradation of polyethylene The problem can be detected before serious ... used in sunscreen cosmetic products, which protect skin from UV attack. UV degradation in material testing The effects of UV degradation on materials that require a long service life can be measured ... in 1 Year ref In Solar Power Modules degradation is a longterm issue according to material testings the efficiency loss by UV degradation is about 6.81 to 9.54 in 20 years. ref http www.rechner photovoltaik.de rechner solardegradation Degradation Calculator German, translation by Google . ref See also Forensic polymer engineering Polymer degradation Depolymerization Stress corrosion cracking ... UV damage to polymers Category Polymers Category Materials degradation Category Ultraviolet radiation ... more details
The Wohl degradation in carbohydrate chemistry is a chain contraction method for aldose s. ref citation last Wohl first A. authorlink Alfred Wohl title Abbau des Traubenzuckers journal Chem. Ber. year 1893 volume 26 issue 1 pages 730 744 doi 10.1002 cber.189302601150 . ref The classic example is the conversion of glucose to arabinose as shown below. The reaction is named after the chemist Alfred Wohl . Image WohlDegradation.png center 600px The Wohl degradation In one modification ref OrgSynth first G za last Braun title D Arabinose prep CV3P0101 volume 20 pages 14 year 1940 collvol 3 collvolpages 101 . ref ref OrgSynth first1 H. T. last1 Clarke first2 S. M. last2 Nagy title Pentaacetyl d gluconitrile prep CV3P0690 volume 20 pages 74 year 1940 collvol 3 collvolpages 690 . ref , glucose d glucose is converted to the glucose oxime by reaction with hydroxylamine and sodium methoxide . In the second step the pentaacetyl glycononitrile is formed by reaction with acetic anhydride in acetic acid with sodium acetate . In this reaction step the oxime is converted into the nitrile with simultaneous conversion of all the alcohol groups to acetate groups. In the final step sodium methoxide in methanol is added on which the nitrile group is split off as sodium cyanide with formation of a new formyl group. Ruff Fenton degradation In a variation the Ruff Fenton degradation Otto Ruff 1898, O. Fenton 1893 converts the aldose first to the alpha hydroxy carboxylic acid with bromine and calcium hydroxide and then to the shortened aldose by reaction with Iron III sulfate and hydrogen peroxide ref Organic syntheses based on name reactions , Volume 22 Alfred Hassner,C. Stumer ref See also Nef reaction References Reflist Category Carbohydrate chemistry Category Elimination reactions Category Degradation reactions Category Name reactions es Degradaci n de Wohl zh ... more details
The Strecker degradation is a chemical reaction which converts an amino acid into an aldehyde by an imine intermediate. It is named after Adolph Strecker , a German chemist. The original observation by Strecker involved the use of alloxan as the oxidant ref cite journal title Notiz ber eine eigenth mliche Oxydation durch Alloxan pages 363&ndash 365 doi 10.1002 jlac.18621230312 first A last Strecker journal Annalen der Chemie volume 123 issue 2 year 1862 ref File Strecker Degradation.png 500px The reaction can take place using a variety of organic and inorganic reagents. ref cite journal title The Strecker Degradation of Amino Acids pages 261&ndash 277 doi 10.1021 cr60156a002 first Alexander last Schonberg coauthors Moubacher, Radwan journal Chem. Rev. volume 50 issue 2 year 1952 ref References reflist Category Organic reactions Category Name reactions Category Degradation reactions de Strecker Abbau ja zh Strecker ... more details
Edman degradation , developed by Pehr Edman , is a method of Protein sequencing sequencing amino acids in a peptide . ref citation last Edman first P. year 1950 title Method for determination of the amino acid sequence in peptides journal Acta Chem. Scand. volume 4 pages 283 293 doi 10.3891 acta.chem.scand.04 0283 . ref In this method, the amino terminal residue chemistry residue is labeled and cleaved from the peptide without disrupting the peptide bonds between other amino acid residues. Mechanism Image EdmanDegradation.png 600px center Edman Degradation with generic amino acid peptide chain. isothiocyanate Phenylisothiocyanate is reacted with an uncharged terminal amino group, under mildly alkaline conditions, to form a cyclical phenylthiocarbamoyl derivative. Then, under acidic conditions, this derivative of the terminal amino acid is cleaved as a thiazolinone derivative. The thiazolinone amino acid is then selectively extracted into an organic solvent and treated with acid to form the more stable phenylthiohydantoin PTH amino acid derivative that can be identified by using chromatography or electrophoresis . This procedure can then be repeated again to identify the next amino acid. A major drawback to this technique is that the peptides being sequenced in this manner cannot have more than 50 to 60 residues and in practice, under 30 . The peptide length is limited due to the cyclical ... acid . An advantage of the Edman degradation is that it only uses 10 100 pico moles of peptide for the sequencing process. Edman degradation reaction is automated to speed up the process. ref cite journal author Niall HD title Automated Edman degradation the protein sequenator journal Meth. Enzymol ... Because the Edman degradation proceeds from the N terminus of the protein, it will not work ... amino acid may be subsequent to identity a Protein of Interest POI . See also Bergmann degradation ... structure Category Proteomics Category Name reactions Category Chemical tests Category Degradation ... more details
Infobox Album See Wikipedia WikiProject Albums Name Degradation Trip Type studio Artist Jerry Cantrell Cover Jerry Cantrell Degradation Trip.jpg Released June 18, 2002 Recorded Fall 2001 at A&M Studios ... Blender magazine Blender Rating 4 5 http www.blender.com guide new 50514 degradation trip.html link ... albums album 104529 review 5941089 degradation trip link Obnoxious Listeners Rating 4 5 http www.obnoxiouslisteners.com album degradation trip jerry cantrell link Last album Boggy Depot br 1998 This album Degradation Trip br 2002 Next album Degradation Trip Volumes 1 & 2 br 2002 Misc Singles Name Degradation Trip Type studio single 1 Anger Rising single 1 date April 2002 single 2 Angel Eyes single 2 date September 2002 Degradation Trip is the second solo album by Alice in Chains guitarist and vocalist ... died two months before its release. Degradation Trip featured two single music single s and was well ... to his work in Alice in Chains. On November 26, 2002, the full Degradation Trip sessions worth of songs was released in its entirely as Degradation Trip Volumes 1 & 2 . Recording and background ... of this follow up, later entitled Degradation Trip , was written in the seclusion of a house in the Cascade ... compared to this. The massive sonic growth from Boggy Depot to Degradation Trip is comparable .... Cantrell was unable to find a replacement and decided to self produce Degradation Trip with his friend ... be released in some form. Indeed, on November 26, 2002, a Degradation Trip Volumes 1 & 2 second version ... has called the single disc release the Reader s Digest version of Degradation Trip . ref Kaye, Don. A Long, Strange Trip Degradation Trip Volumes 1 & 2 November 26, 2002 . Retrieved on 6 20 09. ref ... planned for Degradation Trip however, the group s interest in them lead to Staley writing lyrics ... www.popmatters.com music interviews cantrell jerry 021226.shtml Degradation Trip An Interview with Jerry ... of Degradation Trip , She Was My Girl appeared on the soundtrack , Music from and Inspired ... more details
unreferenced date January 2011 In 1898, Otto Ruff published his work on the transformation of D Glucose to D Arabinose later called the Ruff degradation. In this reaction, D Glucose is converted to D Arabinose . In this reaction, primarily terminal aldehyde group is converted to Carboxylic acid carboxylic group, using selective oxidizing of aldehyde group using Bromine water Bromine Organic chemistry Bromine water and then converted to gluconate ion. After it, Fe OAc sub 3 sub with 30 of H sub 2 sub O sub 2 sub is added. br br Thus COO ion will form CO2 and Stereo Selective compound will form. And below CH2OH will convert to CHO group, thus forming D Arabinose. <No Image> Chemistry stub Category Name reactions de Ruff Abbau zh ... more details
The Marker degradation is a three step chemical synthesis synthetic route in steroid chemistry developed by American chemist Russell Earl Marker in 1938 40. It is used for the production of cortisone and mammalian sex hormone s progesterone , estradiol , etc. from plant steroids, and established Mexico as a world center for steroid production in the years immediately after World War II . ref name landmark citation url http acswebcontent.acs.org landmarks marker marker.html title The Marker Degradation publisher American Chemical Society accessdate 2010 03 03 . ref The discovery of the Marker degradation allowed the production of substantial quantities of steroid hormones for the first time, and was fundamental in the development of the contraceptive pill and corticosteroid anti inflammatory drugs. In 1999, the American Chemical Society and the Sociedad Qu mica de M xico named the route as a National Historic Chemical Landmark. ref name landmark The first large scale application of the route took place in 1943, when Russell Earl Marker collected 10 tons of yam vegetable yam tuber ... degradation led to the development of a Fine chemicals fine chemical industry in Mexico which ... in what would become known as the Marker degradation. Sarsasapogenin was too expensive to be a commercial ... body, as in the industrial process developed after the discovery of the Marker degradation. ref The quantities ..., the Marker degradation relies heavily on kinetic control to degrade the sapogenin side chain ... books.google.com books?id iyzlMSPp EMC&pg PA281 v onepage&q &f false . ref File Marker degradation 1.png .... File Marker degradation 2.png 500px The ester is then hydrolyzed under strongly basic conditions ... a double bond. File Marker degradation 3.png 500px The resulting 3 hydroxypregna 5,16 dien 20 one ... One consequence of this split was that the Marker degradation was never patent ed. ref name ... note References reflist 2 Category Degradation reactions Category Name reactions ... more details
refimprove date November 2009 Concrete degradation may have various causes. Concrete can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage from carbonation, chlorides, sulfates and distilled water . This process adversely affects concrete exposed to these damaging stimuli. Aggregate expansion File ASR cracks concrete step barrier FHWA 2006.jpg thumb right 275px Typical crack pattern associated to the Alkali Silica Reaction alkali silica reaction affecting a concrete step barrier on an US motorway photograph, courtesy of the Federal Highway Administration US Department of Transportation . Various types of aggregate undergo chemical reactions in concrete, leading to damaging expansive phenomena. The most common are those containing reactive silica, that can react in the presence of water with the alkalis in concrete K sub 2 sub O and Na sub 2 sub O, coming principally from cement . Among the more reactive mineral components of some aggregates are opal , chalcedony , flint and strained quartz . Following the Alkali Silica Reaction alkali silica reaction ASR , an expansive gel forms, that creates extensive cracks and damage on structural members. On the surface of concrete pavements the ASR can cause pop outs, i.e. the expulsion of small cones up to 3 cm about in diameter in correspondence of aggregate particles. When some aggregates containing dolomite are used, a dedolomitization reaction occurs where the magnesium carbonate compound reacts with hydroxyl ions and yields magnesium hydroxide and a Carbonate carbonate ion . The resulting expansion may cause destruction of the material. Far less common are pop outs caused by the presence of pyrite , an iron sulfide that generates expansion by forming iron oxide and ettringite . Other reactions and recrystallizations, e.g. hydration of clay minerals in some aggregates, may lead to destructive expansion as well. Corrosion of reinforcement ... more details
, the polymer and surrounding environment. See also Indication of weather degradationEnvironmental stress cracking Weather testing of polymers Photo oxidation process Thermal degradation of polymers Use of stabilisters to enhance weathering resistance Polymer degradation Ozone cracking UV degradation ...Chemically assisted degradation of polymers is a type of polymer degradation that involves a change of the polymer properties due to a chemical reaction with the polymer s surroundings. There are many different types of possible chemical reactions causing degradation however most of these reactions result in the breaking of double bonds within the polymer structure. Examples of chemically assisted degradationDegradation of rubber by ozone One common example of chemically assisted degradation is the degradation ... for degradation to occur. Degradation of poly vinyl chloride PVC Degradation can also occur ... and broken by ozone, just like the degradation of rubbers described above. Degradation of polyester Degradation of polyester may occur without the presence of the acidic catalyst that causes degradation ... degradation mainly at high temperature and pressure during processing. In this process the water ... products may also cause further degradation of the polymer chain. This chain scission lowers average ... and increasing deformation at low stresses. Protection against chemically assisted degradation Both physical and chemical barriers can be used to protect a polymer from chemically assisted degradation ... reacts with the environmental conditions rather than the polymer itself. This barrier involves ... Degradation of Poly ethylene terepthalate Studied by Matrix assisted Laser Desorption Ionisation Mass .... Mitra, S, Ghanbari Siahkali, A, Amdal, K 2006, A novel method for monitoring chemical degradation of crosslinked rubber by stress relaxation under tension , Polymer Degradation and Stability , Vol ... Category Materials degradation ... more details
known for oxidation. See also Chemically Assisted Degradation of Polymers Environmental stress cracking Indication of weather degradation Photo oxidation process Use of stabilisters to enhance weathering ...Thermal degradation of polymers is molecular deterioration as a result of overheating. At high temperatures the components of the long chain backbone of the polymer can begin to separate molecular scission and react with one another to change the properties of the polymer. Thermal degradation can present an upper limit to the service temperature of plastics as much as the possibility of mechanical property loss. Indeed unless correctly prevented, significant thermal degradation can occur at temperatures much lower than those at which mechanical failure is likely to occur. The chemical reactions involved in thermal degradation lead to physical and optical property changes relative to the initially specified properties. Thermal degradation generally involves changes to the molecular weight and molecular ... Degradation of Polymers The Zeus Polymer Minute Bot generated title ref The Mechanism of Thermal Degradation Most types of degradation follow a similar basic pattern. The conventional model for thermal degradation is that of an autoxidation process which involves the major steps of initiation ... degradation involves the loss of a hydrogen atom from the polymer chain as a result of energy input ... atom with an unpaired electron H . Propagation The propagation of thermal degradation can involve ... from the polymer chain . Termination The termination of thermal degradation is achieved by mopping ... or it can be assisted by using stabilizers in the plastic . The Research Methods of Thermal Degradation .... Soldi. Thermal degradation of natrural polymers. Journal of Thermal Analysis and Calorimetry, Vol ... Thermal Degradation Depolymerisation main Depolymerization Under thermal effect, the end of polymer ... Category Polymer chemistry Category corrosion Category Forensic phenomena Category Materials degradation ... more details
Degradation Acid sulfate soil Alkaline soil Desertification Land degradation col2 Environmental impact ...Soil retrogression and degradation are two regressive evolution processes associated with the loss of equilibrium of a stable soil . Retrogression is primarily due to erosion and corresponds to a phenomenon where succession reverts back to pioneer conditions such as bare ground . Degradation is an evolution, different of natural evolution, related to the locale climate and vegetation. It is due to the replacement of the primitive vegetation known as climax by a secondary vegetation. This replacement ... related to human activity. Soil degradation may also be viewed as any change or disturbance to the soil ... of environmental terms. Journal of Environmental Quality 26 581 589. ref At the beginning of a soil ... name, the equilibrium stage of primary succession is the highest natural form of development that the environmental ... vulnerable to the effects of induced retrogression and degradation. Ecological factors influencing soil ... factor for soil degradation and is due to several mechanisms water erosion, wind erosion, chemical degradation and physical degradation. Erosion is strongly related to human activity. For example ... , in particular, is responsible for degradation of forest soils. Agriculture increases the risk ... and degradation main land degradation Crop yield yields impact Recent increases in the human ... ref Many soils suffer from various types of degradation, that can ultimately reduce their ability to produce food resources. Slight degradation refers to land where yield potential has been reduced by 10 , moderate degradation refers to a yield decrease from 10 50 . Severely degraded soils have lost ... spectrum of action. biological diversity soil degradation may involve the disappearance of the climax ..., M. Saul, and A.E. Winter Nelson. 1997. Meanings of environmental terms. Journal of Environmental ... references Category Environmental soil science cs Degradace p d es Retroceso y degradaci n del ... more details
The Von Braun amide degradation is the chemical reaction of a monosubstituted amide with phosphorus pentachloride to give a nitrile and an organo halide . ref cite journal title Ueber die Spaltung des Benzenylmethylimidchlorids author Hans von Pechmann journal Berichte der deutschen chemischen Gesellschaft volume 33 issue 1 pages 611 612 year 1900 url http gallica.bnf.fr ark 12148 bpt6k907551 f616.table doi 10.1002 cber.19000330199 ref ref cite journal title Ueber 1.5 Dibrompentan author von Braun, J. journal Berichte der deutschen chemischen Gesellschaft volume 37 issue 3 pages 3210 3213 year 1904 url doi 10.1002 cber.190403703118 ref ref cite journal title Mechanism of the von Braun amide degradations with carbonyl bromide or phosphorus pentabromide author B. A. Phillips, G. Fodor, J. Gal, F. Letourneau and J. J. Ryan journal Tetrahedron journal Tetrahedron volume 29 issue 21 pages 3309 3327 year 1973 url doi 10.1016 S0040 4020 01 93483 0 ref Image Von Braun Amide Degradation Scheme.png center 400px The von Braun amide degradation See also von Braun reaction References Reflist Category Elimination reactions Category Degradation reactions Category Name reactions zh Von Braun ... more details
Image D dimer.png thumb Principles of D dimer testing Fibrin degradation product FDPs , also known as fibrin split products, are components of the blood produced by clot degeneration. ref name pmid7786784 cite journal author Gaffney PJ, Edgell T, Creighton Kempsford LJ, Wheeler S, Tarelli E title Fibrin degradation product FnDP assays analysis of standardization issues and target antigens in plasma journal Br. J. Haematol. volume 90 issue 1 pages 187 94 year 1995 pmid 7786784 doi 10.1111 j.1365 2141.1995.tb03399.x ref These are produced by the action of plasmin on deposited fibrin. The most notable subtype of fibrin degradation products is D dimer . The levels of these FDPs rises after any thrombotic event. It can be used to test for disseminated intravascular coagulation . ref http peir.path.uab.edu coag article 77.shtml Fibrin Fibrinogen Degradation Products Bot generated title ref See also D dimer References references External links MedlinePlus 003655 medicine stub Category Coagulation system nl Fibrinedegradatieproduct sl Razgradni produkt fibrina ... more details
Orphan date January 2011 In the Gallagher Hollander Degradation 1946 pyruvic acid is removed from a linear aliphatic carboxylic acid yielding a new acid with 2 carbon atoms less ref Vincent P. Hollander and T. F. Gallagher PARTIAL SYNTHESIS OF COMPOUNDS RELATED TO ADRENAL CORTICAL HORMONES. VII. DEGRADATION OF THE SIDE CHAIN OF CHOLANIC ACID J. Biol. Chem. , Mar 1946 162 549 554 http www.jbc.org cgi reprint 162 3 549 Link ref . The original publication concerns the conversion of bile acid in a series of reactions acid chloride 2 formation with thionyl chloride , diazoketone formation 3 with diazomethane , chloromethyl ketone formation 4 with hydrochloric acid , organic reduction of chlorine to methylketone 5 , ketone halogenation to 6 , elimination reaction with pyridine to enone 7 and finally oxidation with chromium trioxide to bisnorcholanic acid 8 . Image Gallagher Hollander Degradation.svg 600px Gallagher Hollander Degradation References reflist Category Organic reactions Category Name reactions Category Degradation reactions es Degradaci n de Gallagher Hollander zh Gallagher Hollander ... more details
Encyclopedia
top
