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  • enzymes
  • If your child has a urea cycle disorder, his liver can't make one of the enzymes the cycle needs. (webmd.com)
  • ammonia
  • and in 1773 it was noted that urea gave off ammonia when heated. (infoplease.com)
  • In 1828 urea also became the first organic compound to be synthesized from inorganic materials (lead or silver cyanate and ammonia) this work was done by German chemist Friedrich Wöhler in 1828. (infoplease.com)
  • In metabolism of proteins and other materials, the ammonia molecule that enters the cycle originates from glutamic acid, but glutamic acid can acquire the group that generates this ammonia from many other amino acids thus most of the nitrogen in protein can eventually be converted to nitrogen in urea. (infoplease.com)
  • The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea ((NH2)2CO) from ammonia (NH3). (wikipedia.org)
  • The urea cycle converts highly toxic ammonia to urea for excretion. (wikipedia.org)
  • Organisms that cannot easily and safely remove nitrogen as ammonia convert it to a less toxic substance such as urea or uric acid. (wikipedia.org)
  • The conversion from ammonia to urea happens in five main steps. (wikipedia.org)
  • The reactions of the urea cycle 1 L-ornithine 2 carbamoyl phosphate 3 L-citrulline 4 argininosuccinate 5 fumarate 6 L-arginine 7 urea L-Asp L-aspartate CPS-1 carbamoyl phosphate synthetase I OTC Ornithine transcarbamoylase ASS argininosuccinate synthetase ASL argininosuccinate lyase ARG1 arginase 1 Before the urea cycle begins ammonia is converted to carbamoyl phosphate. (wikipedia.org)
  • It is based upon the ability of H. pylori to convert urea to ammonia and carbon dioxide. (wikipedia.org)
  • These amino groups are converted to ammonia (NH 3 ), which is toxic to the body and thus must be converted to urea by the liver . (britannica.com)
  • Urea is now prepared commercially in vast amounts from liquid ammonia and liquid carbon dioxide . (britannica.com)
  • Because its nitrogen content is high and is readily converted to ammonia in the soil, urea is one of the most concentrated nitrogenous fertilizers . (britannica.com)
  • Urea also plays a very important role in protein catabolism, removal of toxic ammonia from the body, and the countercurrent system which allows for reabsorption of water and critical ions in the nephrons. (abcam.com)
  • serum
  • Both of these factors make the actual post-dialysis serum urea level higher than expected, and the URR lower than expected, when the extremely simplified equation above, is used. (wikipedia.org)
  • urease
  • this indicates that urease (the enzyme that H. pylori uses to metabolize urea) is present in the stomach, and hence that H. pylori bacteria are present. (wikipedia.org)
  • adduct
  • urea adduct The equilibrium of the reaction is dependent on the concentrations of the reactants, the solvent and the temperature. (wikipedia.org)
  • The urea is added as a supersaturated aqueous solution to compensate for losses due to adduct formation during the process. (wikipedia.org)
  • The urea-paraffin-adduct can be filtered off and thereby separated from the iso-paraffins and other non-paraffinic components. (wikipedia.org)
  • Nitrate
  • Urea nitrate is a fertilizer-based high explosive that has been used in improvised explosive devices in Afghanistan, Pakistan, Iraq, and various other terrorist acts elsewhere in the world, like the 1993 World Trade Center bombings. (wikipedia.org)
  • Urea nitrate is produced in one step by reaction of urea with nitric acid. (wikipedia.org)
  • Urea nitrate explosions may be initiated using a blasting cap. (wikipedia.org)
  • This forms an ionic bond and hence the compound urea nitrate. (wikipedia.org)
  • Urea phosphate is sometimes added to blends which contain calcium nitrate and magnesium nitrate to produce water-soluble formulas such as 15-5-15, 13-2-20, and 13-2-13. (wikipedia.org)
  • What Is Urea Nitrate? (wisegeek.com)
  • In the case of urea nitrate, as with most commercial and military explosives, the fuel and the oxidizer are present in the same molecule, and like most compounds of this type, it is classed as a high explosive. (wisegeek.com)
  • urea nitrate is classed as a secondary explosive, as a small explosive charge is normally required to provide sufficient shock to cause detonation. (wisegeek.com)
  • Urea nitrate does not normally explode if ignited, but burns easily in air, producing carbon dioxide , water and oxides of nitrogen. (wisegeek.com)
  • Urea and nitric acid are both manufactured on a huge scale for use in the fertilizer industry - urea is itself a widely used fertilizer - and the availability of these raw materials in bulk quantities combined with the ease of urea nitrate synthesis has led to this explosive often being favored by terrorist groups. (wisegeek.com)
  • It is thought that urea nitrate was the main explosive used in the 1993 car bomb attack on the World Trade Center. (wisegeek.com)
  • A simple field test can identify urea nitrate by exploiting its reaction with p-dimethylaminocinnamaldehyde (P-DMAC) to form a strongly colored red compound. (wisegeek.com)
  • From your description, very little, if any, urea nitrate would be formed, though I don't know what quantities you are using. (wisegeek.com)
  • If you are concerned about leaving an explosive residue, you can dilute with lots of water when you are finished, which should dissolve any urea nitrate, then you can dispose of it safely. (wisegeek.com)
  • compound
  • The compound is synthesized by gradual addition of urea into a perchloric acid solution: CO(NH2)2 + HClO4 → CO(NH2)2·HClO4 An alternative route is addition of urea to hydrochloric acid solution, followed by addition of sodium perchlorate, and filtration of the salt. (wikipedia.org)
  • The compound is less likely to explode if it is wet, and in the presence of water, it tends to decompose non-violently into urea and nitric acid. (wisegeek.com)
  • Nitric acid and urea do not react explosively, but form a compound that is potentially explosive. (wisegeek.com)
  • carbon
  • Instead, new data indicate that the hydroxymethyl functional group of each imidazolidine ring is attached to the carbon, rather than on the nitrogen atom: Imidazolidinyl urea is produced by the chemical reaction of allantoin and formaldehyde in the presence of sodium hydroxide solution and heat. (wikipedia.org)
  • Instead, new data indicate that one of the hydroxymethyl functional groups of the imidazolidine ring is attached to the carbon, rather than on the urea nitrogen atom: Some people have a contact allergy to imidazolidinyl urea causing dermatitis. (wikipedia.org)
  • The systematic name of this enzyme class is urea:carbon-dioxide ligase (ADP-forming). (wikipedia.org)
  • The entire process converts two amino groups, one from NH4+ and one from Asp, and a carbon atom from HCO3−, to the relatively nontoxic excretion product urea at the cost of four "high-energy" phosphate bonds (3 ATP hydrolyzed to 2 ADP and one AMP). (wikipedia.org)
  • In addition to the n-alkanes are also unbranched fatty acids with more than four carbon atoms, their esters and unbranched fatty alcohols can migrate into the channels of the crystallized urea and form a clathrate. (wikipedia.org)
  • The necessary quantity of urea for the formation of inclusion compounds varies from about 1 to 0.8 mole of urea per methyl- and methylene group in a carbon chain. (wikipedia.org)
  • Patients swallow urea labelled with an uncommon isotope, either radioactive carbon-14 or non-radioactive carbon-13. (wikipedia.org)
  • phosphate
  • The acidity of urea phosphate allows Ca, Mg and P to co-exist in solution. (wikipedia.org)
  • Urea phosphate is often used in Drip irrigation to clean the pipe system. (wikipedia.org)
  • In enzymology, an urea carboxylase (EC 6.3.4.6) is an enzyme that catalyzes the chemical reaction ATP + urea + HCO3- ⇌ {\displaystyle \rightleftharpoons } ADP + phosphate + urea-1-carboxylate The 3 substrates of this enzyme are ATP, urea, and HCO3-, whereas its 3 products are ADP, phosphate, and urea-1-carboxylate (allophanate). (wikipedia.org)
  • The carbamoyl phosphate then enters the urea cycle. (wikipedia.org)
  • Compounds
  • A branching in the fatty acid molecule or an autoxidation result in a large deviation from the straight-chain molecular structure, so that these compounds do not form urea adducts. (wikipedia.org)
  • For the separation of n-paraffins from other hydrocarbon compounds, urea is added with an approximately 20-fold molar excess. (wikipedia.org)
  • Urea and other related compounds do not produce this reaction, reducing the chances of a false positive result. (wisegeek.com)
  • decomposes
  • These two materials are combined under high pressures and elevated temperatures to form ammonium carbamate, which then decomposes at much lower pressures to yield urea and water . (britannica.com)
  • displaystyle
  • Kt/V, like the URR, focuses on urea as the target solute, and is based on the assumption that removal of urea is from a single space - urea distribution volume, or V {\displaystyle V\,} similar in capacity to the total body water. (wikipedia.org)
  • The urea distribution volume V {\displaystyle V\,} , although traditionally thought of as 60% of body weight, may actually be closer to 50% of the body weight in women and 55% in men with stage V (GFR (wikipedia.org)
  • So K ⋅ t {\displaystyle K\cdot t} is also a volume, either m l m i n ⋅ m i n = m l {\displaystyle {\frac {ml}{min}}\cdot min=ml} , or L h r ⋅ h r = L {\displaystyle {\frac {L}{hr}}\cdot hr=L} , and represents the volume of blood (in ml or L) cleared of urea during the dialysis session. (wikipedia.org)
  • The second term, ( 4 − 3.5 ( 1 − U R R ) ) ⋅ 0.55 ⋅ U F V {\displaystyle (4-3.5(1-URR))\cdot {\frac {0.55\cdot UF}{V}}} adjusts for the additional urea that is cleared from the body through volume contraction. (wikipedia.org)
  • dissolves
  • Urea dissolves the intercellular matrix of the cells of the stratum corneum, promoting desquamation of scaly skin, eventually resulting in softening of hyperkeratotic areas. (wikipedia.org)
  • fertilizers
  • Coated urea fertilizers are a group of controlled release fertilizers consisting of prills of urea coated in less-soluble chemicals such as sulfur, polymers, other products or a combination. (wikipedia.org)
  • Another disadvantage has to do with the relatively large particle size of sulfur-coated urea fertilizers, which makes their use on closely mown surfaces like putting greens impractical. (wikipedia.org)
  • Polymer-coated urea, also called plastic-coated urea, or PCU, fertilizers can permit a more precise rate of nitrogen release than sulfur-coated urea products. (wikipedia.org)
  • gradual
  • These coatings permit the gradual release of urea in a controlled fashion, allowing for less-frequent applications. (wikipedia.org)
  • ornithine cycle
  • Years of investigation of the biosynthesis of urea culminated in the proposal of the ornithine cycle (sometimes known as the Krebs urea cycle, named for German-born chemist Hans Krebs) in 1932. (infoplease.com)
  • reaction proceeds
  • The production of DMEU is through the condensation of formaldehyde with ethylene urea: 2CH2O + (C2H4N2H2)CO → (C2H2N2(CH2OH)2)CO The reaction proceeds around 200 °C but this temperature can be brought down to around 70 °C in the presence of an acid catalyst. (wikipedia.org)
  • Methodology
  • This is the methodology for the monthly Urea Outlook report, which is produced by Integer Research on behalf of ICIS. (icis.com)
  • This is the ICIS pricing methodology for urea. (icis.com)
  • citation needed
  • The optimum temperature for microbe activity is approximately 70-90 °F (approx 20-30 °C).[citation needed] Urea-formaldehyde foam insulation (UFFI) dates to the 1930s and made a synthetic insulation with R-values near 5.0 per inch. (wikipedia.org)
  • form
  • Sulfur-coated urea products can only be applied in granular form, and thus cannot be applied via liquid fertilization methods. (wikipedia.org)
  • 4) Arginine is cleaved by arginase to form urea and ornithine. (wikipedia.org)
  • In the urea assay protocol, urea is acted on by enzymes to form a product that reacts with a probe to generate color (ODmax=570nm). (abcam.com)
  • dialysis
  • For the Scottish river see: Urr Water The urea reduction ratio (URR), is a dimensionless number used to quantify dialysis treatment adequacy. (wikipedia.org)
  • It permits easy monitoring of the amount of dialysis therapy delivered to individual patients, as well as across dialysis units, groups of units, states, regions, or countries, because monthly predialysis and postdialysis urea nitrogen values are routinely measured. (wikipedia.org)
  • This gives results that are quite similar to formal urea modeling as long as dialysis treatments of 2-6 hours in duration are given, and Kt/V is between 0.7 and 2.0. (wikipedia.org)
  • stable
  • Thus stearic acid (C18: 0) forms more stable urea adducts compared to oleic acid (C18: 1 cis -9) or linoleic acid (C18: 2 cis -9, cis -12). (wikipedia.org)
  • blood
  • Blood urea nitrogen Gerber GS, Brendler CB. (wikipedia.org)
  • If kidney problems are the main concern, the creatinine levels in your blood will likely also be measured when your blood is tested for urea nitrogen levels. (mayoclinic.org)
  • During the blood urea nitrogen test, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm. (mayoclinic.org)
  • Results of the blood urea nitrogen test are measured in milligrams per deciliter (mg/dL) in the United States and in millimoles per liter (mmol/L) internationally. (mayoclinic.org)
  • It can be used as a blood urea nitrogen assay kit (BUN assay kit). (abcam.com)
  • ab83362 was used as a BUN assay (Blood urea nitrogen assay) to measure urea levels in 80 female Sprague-Dawley rats (age 10-12 months-old). (abcam.com)