Articles de revues : « Urea production »

1

Lemon, Peter W. R., David T. Deutsch et Warren R. Payne. « Urea production during prolonged swimming ». Journal of Sports Sciences 7, n^o 3 (décembre 1989) : 241–46. http://dx.doi.org/10.1080/02640418908729844.

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Zhao, Xin, Baolin Zhang, Sancai Liu et Xiushi Yang. « Evaluation of efficiency of controlled-release N fertiliser on tartary buckwheat production ». Plant, Soil and Environment 67, No. 7 (13 juillet 2021) : 399–407. http://dx.doi.org/10.17221/32/2021-pse.

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To provide reference for scientific management of nitrogen (N) fertiliser on tartary buckwheat, the effects of the mixed application of controlled-release N fertiliser (a kind of thermoplastic polymer-coated urea types that are characterised by a semi-permeable membrane) and common urea was studied in the main tartary buckwheat production area in China. In 2018 and 2019, a two-year field experiment was conducted a randomised block design with five treatments: (1) no nitrogen fertilisation (CK); (2) 100% N from common urea (T1); (3) 15% N from controlled-released urea fertiliser (plastic coated) + 85% N from common urea (T2); (4) 30% N from controlled-released fertiliser + 70% N from urea (T3); (5) 45% N from controlled-released fertiliser + 55% N of urea (T4). The N fertilisation rate was 90 kg N/ha in all fertilisation treatments. The results showed: (1) the mixed application of controlled-release N fertiliser and common urea was conductive to enhance the yield, dry mass, N uptake and apparent N fertiliser efficiency (NFE), compared with a single application of common urea. In two seasons, NFE was 38.6% (T1), 48.6% (T2), 53.6% (T3) and 53% (T4), separately; (2) the mixed application of controlled-release N fertiliser and common urea could significantly increase the soil inorganic N content in the soil surface layer and decreased the leaching loss of N; (3) with the increasing ration of controlled-release N fertiliser, the tendency of increasing N content of crop uptake and soil residual and decreasing rate of N loss and N surplus was visible. Overall, considered the indicators of grain yield, input cost, N utilisation and N balance, the suitable N fertilisation mode for tartary buckwheat production is the mixed application of 30% controlled-release N fertiliser and 70% common urea when 90 kg N/ha is applied.

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Carraro, F., T. D. Kimbrough et R. R. Wolfe. « Urea kinetics in humans at two levels of exercise intensity ». Journal of Applied Physiology 75, n^o 3 (1 septembre 1993) : 1180–85. http://dx.doi.org/10.1152/jappl.1993.75.3.1180.

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A primed constant infusion of [15N2]urea was used to quantify the response of urea production to exercise at 40 and 70% maximal oxygen consumption on a treadmill. Total urea production, urea production from recycled N, urea production from nonrecycled N, and urea N recycled back into body protein were calculated. Most components of urea kinetics were unaffected by exercise at either intensity. The rate of urea reincorporated into protein was significantly increased during exercise and recovery at both levels of exercise. We conclude that exercise does not stimulate urea production but that there may be an accelerated reincorporation of urea N back into body protein.

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Wheeler, R. A., A. A. Jackson et D. M. Griffiths. « Urea production and recycling in neonates ». Journal of Pediatric Surgery 26, n^o 5 (mai 1991) : 575–77. http://dx.doi.org/10.1016/0022-3468(91)90710-b.

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Bozzano, G., M. Dente et F. Zardi. « New internals for urea production reactors ». Journal of Chemical Technology & ; Biotechnology 78, n^o 2-3 (2003) : 128–33. http://dx.doi.org/10.1002/jctb.694.

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Hamadeh, Mazen J., et L. John Hoffer. « Tracer methods underestimate short-term variations in urea production in humans ». American Journal of Physiology-Endocrinology and Metabolism 274, n^o 3 (1 mars 1998) : E547—E553. http://dx.doi.org/10.1152/ajpendo.1998.274.3.e547.

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Urea production rate (Ra) is commonly measured using a primed continuous tracer urea infusion, but the accuracy of this method has not been clearly established in humans. We used intravenous infusions of unlabeled urea to assess the accuracy of this technique in normal, postabsorptive men under the following four different conditions: 1) tracer [13C]urea was infused under basal conditions for 12 h (control); 2) tracer [13C]urea was infused for 12 h, and unlabeled urea was infused from hours 4 to 12 at a rate twofold greater than the endogenous Ra (“step” infusion); 3) tracer [13C]urea was infused for 12 h, and unlabeled urea was infused from hours 4 to 8 (“pulse” infusion); and 4) tracer [13C]urea was infused for 9 h, and unlabeled alanine was infused at a rate of 120 mg ⋅ kg−1 ⋅ h−1(1.35 mmol ⋅ kg−1 ⋅ h−1) from hours 4 to 9. Urea Ra was calculated using the isotopic steady-state equation (tracer infusion rate/tracer-to-tracee ratio), Steele’s non-steady-state equation, and urinary urea excretion corrected for changes in total body urea. For each subject, endogenous urea Ra was measured at hour 4 of the basal condition, and the sum of this rate plus exogenous urea input was considered as “true urea input.” Under control conditions, urea Ra at hour 4 was similar to that measured at hour 12. After 8-h step and 4-h pulse unlabeled urea infusions, Steele’s non-steady-state equation underestimated true urea input by 22% (step) and 33% (pulse), whereas the nonisotopic method underestimated true urea input by 28% (step) and 10% (pulse). Similar conclusions were derived from the alanine infusion. These results indicate that, although Steele’s non-steady-state equation and the nontracer method more accurately predict total urea Ra than the steady-state equation, they nevertheless seriously underestimate total urea Ra for as long as 8 h after a change in true urea Ra.

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Maynard, Elizabeth T. « Nitrogen Sources for Tomato and Pepper Production ». HortScience 32, n^o 3 (juin 1997) : 518C—518. http://dx.doi.org/10.21273/hortsci.32.3.518c.

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Three nitrogen sources applied through drip irrigation were compared to preplant-applied urea to evaluate their effects on tomato (Lycopersicon esculentum Mill.) and bell pepper (Capsicum annum L.) earliness, yield, and blossom end rot (BER) in 1995 and 1996. Calcium nitrate (CaNO3), urea ammonium nitrate (UAN), and ammonium nitrate (NH4NO3) were applied at 11.2 kg N/ha weekly beginning 2 weeks after transplanting for a total of 8 weeks. The urea treatment received 112 kg N/ha before planting and fertigated treatments received 22.4 kg N/ha from urea before planting. In 1995 only, two additional treatments were fertilized with chicken manure only (1.3N–0.7P–0.8K) at 112 kg N/ha and 168 kg N/ha. In 1996, nitrogen treatments were compared at two levels of potassium fertilization: 0 or 269 kg K/ha. `Sunrise' or `Mountain Spring' tomatoes and `Ranger' peppers were transplanted into black plastic in mid to late June each year. Nitrogen treatments had no effect on marketable or total yield, fruit size, or BER of tomatoes. Total pepper yield was lower with urea than with CaNO3; early and marketable yields showed similar trends, but differences were not consistently significant. UAN and NH4NO3 pepper yields were usually similar to yield with CaNO3, but did not always differ from urea yields. Compost treatments produced yields intermediate between urea and fertigated treatments in 1995. In 1996, peppers from UAN and NH4NO3 plots had more BER (0.5% to 1%) than CaNO3 plots (0%); urea plots had an intermediate amount of BER (0.2%).

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Zhu, Xiaoyan, Jianchao Chen, Jieyu Chen, Xinrong Lei et Chunjie Yan. « Urea intercalation compound production in industrial scale for paper coating ». Chemical Industry and Chemical Engineering Quarterly 20, n^o 2 (2014) : 241–48. http://dx.doi.org/10.2298/ciceq121025007z.

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Urea intercalation compounds were produced in a new designed industrial scale. The conditions and locations of the new industrial process for the production of urea intercalation compound pigment were studied through the control of correlative parameters. Properties of the compound pigment such as particle morphology, particle size distribution and viscosity, were analyzed to evaluate its potentiality for paper coating application. Results showed that the intercalation ratio of urea intercalation compound increased from 6.3% with 2wt. % of urea addition to 56.08% with 6wt.% of urea addition. Viscosity concentration of urea intercalation compound improved from 69% of original kaolinite to the highest value, 74.23% of the compound. Particle size distribution was centralized. Properties of light weight papers coated with urea intercalation compound showed interesting results, similar to a standard grade.

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Osiecka, Anna, Patrick J. Minogue et Dwight K. Lauer. « Utilization of Urea or Polymer-Coated Urea in Florida Slash Pinestraw Production ». Forest Science 67, n^o 6 (25 octobre 2021) : 740–56. http://dx.doi.org/10.1093/forsci/fxab034.

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Abstract Controlled-release fertilizers may improve productivity and mitigate environmental hazards in Southern pine plantations intensively managed for pinestraw harvesting. We examined the effects of pinestraw removal and fertilization with conventional and polymer-coated urea (PCU) on foliar, needlefall, and pinestraw nutrients and yields in a North Florida slash pine (Pinus elliottii Engelm.) plantation. Raking treatments (raked or nonraked) were applied annually in February 2014–2017. Fertilization treatments (PCU at 0, 28, 56, 140, or urea at 56 kg N ha−1 year−1) were applied annually in June 2014–2016. Four years of pinestraw removal did not affect needlefall mass or foliar and needlefall nutrient concentrations. The positive fertilization rate effect on pinestraw yield, needlefall mass, foliar, needlefall, and pinestraw total Kjeldahl nitrogen (TKN) and K concentrations, and on foliar and needlefall Ca concentrations increased in magnitude with subsequent applications. TKN, total P, and K concentrations were lower in needlefall and pinestraw relative to foliage by 65%–90%, whereas Ca concentrations were higher by 120%–180%. Three PCU applications at 140 N ha−1 year−1 increased three-year cumulative pinestraw yield over the control by 19% and TKN, K, Ca, and Mg removals by 49%, 86%, 24%, and 32%, respectively. Responses to PCU did not differ from urea.

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Dai, Ben Lin, An Feng Zhu, Fei Hu Mu, Ning Xu et Zhen Wu. « Urea (CO(NH₂)₂) Pretreatment Improve Biogas Production Performance of Rice Straw ». Applied Mechanics and Materials 587-589 (juillet 2014) : 896–99. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.896.

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To discuss the internal effect of urea (CO(NH2)2) pretreatment on anaerobic digestion biogas production of rice straw waste, a self-designed laboratory-scale continuous anaerobic biogas digester was used in this study. Anaerobic biogas slurry, urea pretreatment and anaerobic digestion were evaluated for biogas production from rice straw. The results showed that the peak value of biogas production was attained on the 17th day by using 6% urea pretreatment on rice straw. However, the highest CH4 content was 49.8% on the 15th day for the 8% urea-treated rice straw. The cumulative biogas production of 6% urea pretreatment was the highest, about 16 540 mL, which was followed by 2% urea (12 283 mL), 8% urea (9 883 mL), and 4% urea (5 668 mL).

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Jahoor, F., et R. R. Wolfe. « Regulation of urea production by glucose infusion in vivo ». American Journal of Physiology-Endocrinology and Metabolism 253, n^o 5 (1 novembre 1987) : E543—E550. http://dx.doi.org/10.1152/ajpendo.1987.253.5.e543.

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We have investigated the acute in vivo regulation of urea production in normal postabsorptive volunteers by administering a primed constant infusion of 15N2-urea to measure urea production during the constant intravenous infusion of equivalent molar quantities of exogenous nitrogen, given as alanine or glutamine, either with or without a simultaneous infusion of glucose at 4 mg.kg-.min-1. These responses were compared with the response to the infusion of glucose alone. Both amino acid infusions elicited significant (P less than 0.05) and identical (26%) increases in urea production over 4 h. When the glucose infusion was added to the amino acid infusions, urea production remained constant, despite the comparable increases in plasma total nonessential amino nitrogen, as were observed with the amino acid infusions alone. Glucose infused alone elicited a significant (P less than 0.05) reduction (18%) in urea production but no corresponding change in plasma total amino nitrogen. We conclude that 1) infused glucose or its hormonal response suppresses urea production by blunting the normal hepatic ureagenic response to a fixed nitrogen load, 2) this suppressive effect is not mediated via a reduction in substrate (nitrogen) supply, and 3) the inhibition of hepatic gluconeogenesis from amino acids represents one component of this suppressive effect, and direct suppression of urea cycle activity probably represents another component.

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Dodgson, S. J., et R. E. Forster. « Carbonic anhydrase : inhibition results in decreased urea production by hepatocytes ». Journal of Applied Physiology 60, n^o 2 (1 février 1986) : 646–52. http://dx.doi.org/10.1152/jappl.1986.60.2.646.

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The amount of urea produced in 60 min, [urea]t = 60, from intact guinea pig hepatocytes incubated in NH4Cl, oleate, lactate, NaHCO3, and ornithine at 37 degrees C at pH 7.1 is decreased by ethoxzolamide (EZ): Ki,EZ [urea]t = 60 +/- SD at 37 degrees C, pH 7.1 is 0.14 +/- 0.11 mM (10 Dixon plots). This value is in the same range as Ki,EZ for carbonic anhydrase (CA) activity of disrupted hepatocytes at 37 degrees C: 0.08 +/- 0.06 mM (2). [Urea]t = 60 is pH dependent whether external CO2 is supplied (25 mM HCO-3, 95% O2–5% CO2 and 5 mM HCO-3, 99% O2–1% CO2) or not [20 mM N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES), 100% O2]. Ki,EZ [urea]t = 60 is independent of both external pH and external total CO2. Ki,EZ (CA) of disrupted mitochondria at 37 degrees C is 0.033 +/- 0.013 microM (2). This value was approximately 3,000-fold lower than the Ki,EZ [urea]t = 60 for intact hepatocytes or Ki,EZ (CA) for disrupted hepatocytes. These results support the general hypothesis that mitochondrial CA is involved in urea synthesis by intact hepatocytes and that cytosolic components raise the experimentally determined Ki,EZ [urea]t = 60. We also conclude that the value of Ki,EZ [urea]t = 60 is independent of the availability of the substrate HCO-3 from external sources.

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Ahmed, Osumanu H., Aminuddin Hussin, Husni M. H. Ahmad, Anuar A. Rahim et Nik Muhamad Abd Majid. « Enhancing the Urea-N Use Efficiency in Maize (Zea mays) Cultivation on Acid Soils Amended with Zeolite and TSP ». Scientific World JOURNAL 8 (2008) : 394–99. http://dx.doi.org/10.1100/tsw.2008.68.

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Ammonia loss significantly reduces the urea-N use efficiency in crop production. Efforts to reduce this problem are mostly laboratory oriented. This paper reports the effects of urea amended with triple superphosphate (TSP) and zeolite (Clinoptilolite) on soil pH, nitrate, exchangeable ammonium, dry matter production, N uptake, fresh cob production, and urea-N uptake efficiency in maize (Zea mays) cultivation on an acid soil in actual field conditions. Urea-amended TSP and zeolite treatments and urea only (urea without additives) did not have long-term effect on soil pH and accumulation of soil exchangeable ammonium and nitrate. Treatments with higher amounts of TSP and zeolite significantly increased the dry matter (stem and leaf) production of Swan (test crop). All the treatments had no significant effect on urea-N concentration in the leaf and stem of the test crop. In terms of urea-N uptake in the leaf and stem tissues of Swan, only the treatment with the highest amount of TSP and zeolite significantly increased urea-N uptake in the leaf of the test crop. Irrespective of treatment, fresh cob production was statistically not different. However, all the treatments with additives improved urea-N uptake efficiency compared to urea without additives or amendment. This suggests that urea amended with TSP and zeolite has a potential of reducing ammonia loss from surface-applied urea.

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Daryatmo, Joko, Wida Wahidah Mubarokah et B. Budiyanto. « Pengaruh Pupuk Urea terhadap Produksi dan Pertumbuhan Rumput Odot (Pennisetum purpureum cv Mott) ». Jurnal Ilmu Peternakan dan Veteriner Tropis (Journal of Tropical Animal and Veterinary Science) 9, n^o 2 (23 septembre 2019) : 62. http://dx.doi.org/10.30862/jipvet.v9i2.63.

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This study aims to determine the effect of 4 doses of urea fertilizer on production and growth of Odot grass (Pennisetum Purpureum cv. Mott). The experimental design used was a completely randomized design (CRD) pattern in line with 4 treatments and each treatment consisted of 5 replications. The treatment used is Control (P0), urea at a dose of 100 kg/ha (P1), urea at a dose of 150 kg/ha (P2), urea at a dose of 200 kg/ha (P3). The parameters observed were number of tillers, stem length, leaf length, grass height and grass production. The results of statistical analysis showed that the treatment of urea fertilizer had no significant effect on plant height. The treatment of urea fertilizer had a significant effect (P<0.05) on number of tillers, stem length, leaf length and grass production. It can be concluded that the administration of urea fertilizer can increase the number of tillers, stem length, leaf length and odot grass production compared to odot grass that is not given urea fertilizer. Keywords: Urea, Fertilizer, Growth, Production, Pennisetum purpureum cv Mott

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Freyse, E. J., et S. Knospe. « Estimation of Urea Production Rate With [15N2]Urea and [13C]Urea to Measure Catabolic Rates inDiabetes Mellitus ». Isotopes in Environmental and Health Studies 34, n^o 1-2 (septembre 1998) : 107–18. http://dx.doi.org/10.1080/10256019708036338.

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McClelland, Irene S. M., Chandarika Persaud et Alan A. Jackson. « Urea kinetics in healthy women during normal pregnancy ». British Journal of Nutrition 77, n^o 2 (février 1997) : 165–81. http://dx.doi.org/10.1079/bjn19970022.

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Urea kinetics were measured in normal women aged 22-34 years at weeks 16, 24 and 32 on either their habitual protein intake (HABIT.) or a controlled intake of 60 g protein/d (CONTROL), using primed-intermittent oral doses of [15N15N]urea and measurement of plateau enrichment in urinary urea over 18 h (ID) or a single oral dose of [15N15N]urea and measurement of enrichment of urea in urine over the following 48 h (SD). The intake of protein during HABIT-ID (80 g/d) was greater than that on HABIT-SD (71 g/d); urea production as a percentage of intake was significantly greater at week 16 for HABIT-ID than HABIT-SD, whereas urea hydrolysis at week 16 was greater for HABIT-SD than HABIT-ID and urea excretion at week 32 was greater for HABIT-ID than HABIT SD. The combined results for HABIT-ID and HABIT-SD showed a significant reduction in urea production at week 32 compared with week 24. Urea excretion decreased significantly from week 16 to week 24 with no further decrease to week 32 and urea hydrolysis was significantly greater at week 24 than either week 16 or week 32. Compared with HABIT, on CONTROL there was a decrease in urea production at week 16, and urea excretion was significantly reduced at week 16. For all time periods urea production was closely related to the sum of intake plus hydrolysis. Hydrolysis was greatest at week 24 and closely related to urea production. There was a significant inverse linear relationship overall for hydrolysis as a proportion of production and excretion as a proportion of intake. The results show that on HABIT N is more effectively conserved in mid-pregnancy through an increase in urea hydrolysis and salvage, and during late pregnancy through a reduction in urea formation. Lowering protein intake at any stage of pregnancy increased the hydrolysis and salvage of urea. The staging of these changes was later than that in pregnancy in Jamaica.

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GUO, J. M., J. Q. XUE, A. D. BLAYLOCK, Z. L. CUI et X. P. CHEN. « Film-mulched maize production : response to controlled-release urea fertilization ». Journal of Agricultural Science 155, n^o 8 (3 août 2017) : 1299–310. http://dx.doi.org/10.1017/s002185961700048x.

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SUMMARYOptimal nitrogen (N) management for maize in the film-mulched production systems that are widely used in dryland agriculture is difficult because top-dressing N is impractical. The current research determined how matching N supply and demand was achieved before and after silking stages, when single applications of controlled release urea (CRU) were combined with conventional urea in film-mulched maize production. The CRU: urea mixture was applied in a 1 : 2 or 2 : 1 ratio and all three fertilizer regimes (urea alone and CRU: urea at 1 : 2 or 2 : 1) were applied at N rates of 180 and 240 kg/ha over 2 years. The 1 : 2 CRU: urea mixture, applied once at 180 kg N/ha, was found to synchronize N supply with demand, thereby reducing N losses. The highest grain yields (11·8–12·0 t/ha), N uptake (232–239 kg/ha), N recovery (65·8–67·7%) and high net economic return were achieved with this regime. These results indicate that a single application of a mixture of CRU and urea can synchronize N supply with demand and provide higher yields and profits than conventional N fertilization in film-mulched maize systems.

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YAMAMOTO, Nami, Hiroshi UZU et Akira TOTSUKA. « Conditions of Urea Production by Sake Yeast ». JOURNAL OF THE BREWING SOCIETY OF JAPAN 84, n^o 12 (1989) : 883–87. http://dx.doi.org/10.6013/jbrewsocjapan1988.84.883.

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Pierzynski, G. M., M. F. Vigil et D. E. Kissel. « Urea nitricphosphate for cool‐season grass production ». Communications in Soil Science and Plant Analysis 24, n^o 13-14 (août 1993) : 1665–81. http://dx.doi.org/10.1080/00103629309368907.

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Boggs, Bryan K., Rebecca L. King et Gerardine G. Botte. « Urea electrolysis : direct hydrogen production from urine ». Chemical Communications, n^o 32 (2009) : 4859. http://dx.doi.org/10.1039/b905974a.

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Miranda, Eval O., Victor H. R. Silva, Mirtânia A. Leão, Elaine C. M. Cabral-Albuquerque, Silvio Cunha et Rosana L. Fialho. « Mechanochemical Production of Urea-citric Acid Copolymer ». IOP Conference Series : Materials Science and Engineering 958 (27 octobre 2020) : 012008. http://dx.doi.org/10.1088/1757-899x/958/1/012008.

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Matijašević, Ljubica, Igor Dejanović et Hrvoje Lisac. « Treatment of wastewater generated by urea production ». Resources, Conservation and Recycling 54, n^o 3 (janvier 2010) : 149–54. http://dx.doi.org/10.1016/j.resconrec.2009.07.007.

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Wright, Patricia A., et Michelle D. Land. « Urea Production and Transport in Teleost Fishes ». Comparative Biochemistry and Physiology Part A : Molecular & ; Integrative Physiology 119, n^o 1 (janvier 1998) : 47–54. http://dx.doi.org/10.1016/s1095-6433(97)00407-8.

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Van Dijk, D. P. J., S. W. M. Olde Damink, C. H. C. Dejong et M. C. G. van der Poll. « OP002 : Enteral Glutamine Administration Increases Urea Production ». Clinical Nutrition 33 (septembre 2014) : S1. http://dx.doi.org/10.1016/s0261-5614(14)50002-7.

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Nuryawan, A., I. Risnasari, T. Sucipto, A. Heri Iswanto et R. Rosmala Dewi. « Urea-formaldehyde resins : production, application, and testing ». IOP Conference Series : Materials Science and Engineering 223 (juillet 2017) : 012053. http://dx.doi.org/10.1088/1757-899x/223/1/012053.

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Pittiruti, Mauro. « Determinants of Urea Nitrogen Production in Sepsis ». Archives of Surgery 124, n^o 3 (1 mars 1989) : 362. http://dx.doi.org/10.1001/archsurg.1989.01410030112019.

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Alfian, Mohammad, et Widodo W. Purwanto. « Multi‐objective optimization of green urea production ». Energy Science & ; Engineering 7, n^o 2 (20 février 2019) : 292–304. http://dx.doi.org/10.1002/ese3.281.

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任, 军. « Research Progress in Ammonia Production from Urea ». Journal of Advances in Physical Chemistry 11, n^o 04 (2022) : 226–33. http://dx.doi.org/10.12677/japc.2022.114025.

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Alkanani, Thamir, et Angus F. MacKenzie. « Banding urea and lignosulfonate in corn (Zea mays L.) production and 15N recovery ». Canadian Journal of Soil Science 76, n^o 3 (1 août 1996) : 365–71. http://dx.doi.org/10.4141/cjss96-044.

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The use of urea in corn (Zea mays L.) production is common. Under current N fertilizer recommendations for corn, urea may have adverse effects on corn growth when applied in a band. The effects of ammonium lignosulfonate (LS) on corn growth and on N uptake from the banded application of urea and diammonium phosphate (DAP) mixtures were investigated on two soils from eastern Quebec. Field experiments were initiated in the first week of May 1991 on an Ormstown silty clay and a Ste. Rosalie clay soils (fine, mixed, nonacid, mesic Typic Humaquepts). Treatments were two rates of urea (30 and 90 kg urea-N ha−1) in combination with DAP (14 kg N ha−1), with or without banded fertilizer solutions of LS (8 kg N ha−1) applied at planting 5 cm to the side and 3 cm below the seed. A no treatment control was included. The low rate of urea and DAP (no LS added) resulted in a 19 and 24% increase in grain yield at the Ste. Rosalie and Ormstown, respectively, when compared with the unfertilized plots. When compared with the unfertilized treatment, the high rate of urea and DAP (no LS added) caused 10% increase in grain yield. However, addition of LS to the high rate of urea and DAP increase grain yield by band 20%. In general, LS significantly increased corn N uptake from urea on both soils. Separate 15N field experiments were initiated in June 1991. Mean recovery of 15N in total dry matter (grain and stover) was 51.9% in Ormstown and 47.9% in Ste. Rosalie soil. Denitrification estimates, calculated as 15N not accounted for, were not affected by LS and the rate of banded urea-N. Immobilization of 15N ranged from 17.8% to 30.9% of the applied labelled urea. The rate of urea-N banded had no significant effect on immobilization, but LS resulted in significantly less 15N immobilized. These observations suggest that LS can reduce the biological immobilization of urea-N and increase the efficiency of urea fertilizer by reducing the negative effects of banding high levels of urea, while attaining benefits of band placement. Key words: Lignosulfonate, corn, urea, 15N

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Urban, W. J., W. L. Hargrove, B. R. Bock et R. A. Raunikar. « Evaluation of Urea-Urea Phosphate as a Nitrogen Source for No-tillage Production ». Soil Science Society of America Journal 51, n^o 1 (janvier 1987) : 242–46. http://dx.doi.org/10.2136/sssaj1987.03615995005100010049x.

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Ahmed, Shafi. « Urea Fertilizer for Bangladesh Challenges and Opportunity ». Journal of Chemical Engineering 26 (24 mars 2012) : 22–26. http://dx.doi.org/10.3329/jce.v26i1.10177.

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The outlook for Urea Fertilizer at present and in coming years for Bangladesh-is a very much concerned issue and studied in the paper. The urea production vs. design capacity of all Fertilizer Plants and consumption has been shown. Main constraint for reduced urea production is identified as Natural gas shortage. To meet countries demand, the possibility of import from global urea supply and its impact on economy is also studied. Analyzing all the above; support to Urea Fertilizer factories- to ensure food security of the country - has been emphasized. Daily Natural Gas requirement for maintaining urea production is estimated. DOI: http://dx.doi.org/10.3329/jce.v26i1.10177 JCE 2011; 26(1): 22-26

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Beresford, R. M., I. J. Horner et P. N. Wood. « Autumnapplied urea and other compounds to suppress Venturia inaequalis ascospore production ». New Zealand Plant Protection 53 (1 août 2000) : 387–92. http://dx.doi.org/10.30843/nzpp.2000.53.3614.

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The effect of urea applied to apple leaves in autumn on production of ascospores of Venturia inaequalis (black spot) was quantified in four studies Autumn urea at concentrations from 020 reduced ascospore production in spring in proportion to the log of the urea concentration A single application of 5 urea sprayed onto fallen leaves gave an 88 decrease in ascospore production Urea applied to apple trees before leaf fall significantly reduced black spot disease on leaves the following spring in cv Fuji but not in cv Royal Gala Ascospore production was reduced by the fungicide cupric hydroxide but was not affected by a low concentration of fish fertilizer Three methods of ascospore assessment were used to detect differences in ascospore production

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Mutsvangwa, Timothy, Jock G. Buchanan-Smith et Brian W. McBride. « Effects of in vitro addition of ammonia on the metabolism of 15N-labelled amino acids in isolated sheep hepatocytes ». Canadian Journal of Animal Science 79, n^o 3 (1 septembre 1999) : 321–26. http://dx.doi.org/10.4141/a98-082.

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Isolated hepatocytes prepared from sheep were used to determine the effects of added ammonia (as NH4Cl) on the flux of 15N from 15N-labelled amino acids to [14N15N]urea and [15N15N]urea. Hepatocyte suspensions were incubated with NH4Cl (0, 0.31, 0.63 and 1.25 mM) in the presence of L-[15N]alanine, L-[15N]methionine, L-[15N]leucine or L-[15N]phenylalanine (1.0 mM final concentration in the incubation media). Following 1.5 h incubation, addition of NH4Cl increased total urea and unlabelled (14N14N) urea production in all incubations (P < 0.001). Adding NH4Cl did not affect 15N isotopic enrichment of [14N15N]urea (P = 0.705) and [15N15N]urea (P = 0.204), or production of [14N15N]urea (P = 0.279) and [15N15N]urea (P = 0.708) in isolated hepatocytes incubated with [15N]alanine. Addition of NH4Cl increased [14N15N]urea production in incubations containing [15N]methionine (quadratic effect, P = 0.019), but had no effect in incubations containing [15N]leucine (P = 0.107) or [15N]phenylalanine (P = 0.135). There was no detectable production of [15N15N]urea in incubations containing [15N]methionine, [15N]leucine and [15N]phenylalanine. In all incubations, unlabelled (14N14N) urea was the predominant form of urea, indicating that isolated sheep hepatocytes can detoxify excess NH3 by channelling NH3-N into both mitochondrial carbamoyl phosphate and cytoplasmic aspartate synthesis. Key words: Sheep, liver cells, amino acids, ureagenesis, ammonia, 15N

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Obitsu, T., D. Bremner, E. Milne et G. E. Lobley. « Effect of abomasal glucose infusion on alanine metabolism and urea production in sheep ». British Journal of Nutrition 84, n^o 2 (août 2000) : 157–63. http://dx.doi.org/10.1017/s0007114500001380.

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The effect of abomasal infusion of glucose (120 kJ/d per kg body weight (BW)0·75, 758 mmol/d) on urea production, plasma alanine-N flux rate and the conversion of alanine-N to urea was studied in sheep offered a low-N diet at limited energy intake (500 kJ/d per kg BW0·75), based on hay and grass pellets. Glucose provision reduced urinary N (P= 0·040) and urea (P= 0·009) elimination but this was offset by poorer N digestibility. Urea-N production was significantly reduced (822v. 619 mmol/d,P= 0·024) by glucose while plasma alanine-N flux rate was elevated (295v. 342 mmol/d,P= 0·011). The quantity of urea-N derived from alanine tended to be decreased by glucose (127v. 95 mmol/d) but the fraction of urea production from alanine was unaltered (15 %). Plasma urea and alanine concentrations (plus those of the branched chain amino acids) decreased in response to exogenous glucose, an effect probably related to enhanced anabolic usage of amino acids and lowered urea production.

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Hansell, Dennis A., et John J. Goering. « A Method for Estimating Uptake and Production Rates for Urea in Seawater using [14C] Urea and [15N] Urea ». Canadian Journal of Fisheries and Aquatic Sciences 46, n^o 2 (1 février 1989) : 198–202. http://dx.doi.org/10.1139/f89-027.

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Improved estimates of the rates of urea production and uptake by natural populations of phytoplankton were made after determining the change in 15N-atom% enrichment of urea during incubations. A [14C] urea method is described by which the change in enrichment is measured. Estimates of uptake rates are increased (relative to uptake rates determined without correction for isotope dilution) by up to 83% using a 15N accumulation model and by >210% using a 15N disappearance model. A discrepancy exists between [15N] urea removed from the aqueous phase and 15N accumulated in the particulate phase at stations occupied in the northeastern Bering Sea. The ability to find in the particulate fraction the 15N removed from solution as [15N] urea was improved by 72% following removal of the >20-μm particulate fraction. This corresponded to only a 4% reduction in the concentration of chlorophyll a and a 37% reduction in the concentration of particulate N. Removal of microzooplankton may have improved the efficiency of urea-N retention by phytoplankton.

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Chauhan, H. S., et B. Mishra. « Fertilizer–use efficiency of amended urea materials in flooded rice ». Journal of Agricultural Science 112, n^o 2 (avril 1989) : 277–81. http://dx.doi.org/10.1017/s0021859600085178.

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summaryIn a field experiment on a typic hapludoll in 1983 and 1984, deep placement of urea supergranules at 40 and 80 kg N/ha proved to be the best N source, of five tested, for grain production, but at 120 kg N/ha it was similar to neem-cake-coated urea. The results showed that deep placement of urea supergranules can save fertilizer use by 60% compared with prilled urea to obtain the same yield. Shellac-coated urea and dicyandiamide-coated urea was more effective than prilled urea in 1984. Differences in dry-matter production and grain yield were directly related to N uptake by the plants. On average, apparent recovery of applied N increased from 35% for prilled urea to 55, 52·5,46·5 and 37·5% for urea supergranules, neem-cake-coated urea, shellac-coated urea and dicyandiamide-coated urea, respectively.

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Othman, Mohd Roslee, M. R. Anuar et W. J. N. Fernando. « Production of Layered Hydrotalcite Using Tapai as Fuel ». Advanced Materials Research 545 (juillet 2012) : 401–4. http://dx.doi.org/10.4028/www.scientific.net/amr.545.401.

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Lamellar hydrotalcite (HT) was synthesized in the laboratory following combustion method. Tapai fueled HT was found to exhibit more orderly packed microstructure and was more crystalline in nature than its urea fueled counterpart, particularly at higher combustion temperature. The pore structure of tapai fueled HT resembled that of bottle neck with possibility of tapered with open-end that might also be present. The crystal size of tapai fueled HT was larger than urea fueled HT but greater size reduction was experienced by the former material, suggesting that more energy might have been supplied to the sample to disintegrate the particles, since tapai has higher and cleaner carbohydrate source than urea.

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Koivunen, Marja E., Christophe Morisseau, William R. Horwath et Bruce D. Hammock. « Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea (ureaformaldehyde) as nitrogen source ». Canadian Journal of Microbiology 50, n^o 3 (1 mars 2004) : 167–74. http://dx.doi.org/10.1139/w04-001.

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Methylene ureas (MU) are slow-release nitrogen fertilizers degraded in soil by microbial enzymatic activity. Improved utilization of MU in agricultural production requires more knowledge about the organisms and enzymes responsible for its degradation. A Gram-negative, MU-degrading organism was isolated from a soil in Sacramento Valley, California. The bacterium was identified as Agrobacterium tumefaciens (recently also known as Rhizobium radiobacter) using both genotypic and phenotypic characterization. The pathogenic nature of the organism was confirmed by a bioassay on carrot disks. The MU-hydrolyzing enzyme (MUase) was intracellular and was induced by using MU as a sole source of nitrogen. The bacterial growth was optimized in NH4Cl, urea, or peptone, whereas the production and specific activity of MUase were maximized with either NH4Cl or urea as a nitrogen source. The result has a practical significance, demonstrating a potential to select for this plant pathogen in soils fertilized with MU.Key words: methylene urea, ureaformaldehyde, slow-release fertilizer, soil, nitrogen, isolation, Agrobacterium tumefaciens, Rhizobium radiobacter.

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Mantovani, José Ricardo, Jéssica da Silva Bernardes, Belchior de Souza Costa et Gisele de Fátima Esteves. « Production and nutritional value of Mombaça grass with application of whey as an alternative nitrogen source ». Research, Society and Development 11, n^o 4 (12 mars 2022) : e10811427158. http://dx.doi.org/10.33448/rsd-v11i4.27158.

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Whey is a waste generated in large quantities in dairy industries, and its use in agriculture as a source of nutrients can be an appropriate destination. Thus, the objective of this study was to evaluate the effect of whey as a nitrogen source for production and nutritional value of Mombaça grass. The experiment was conducted in pots, in a randomized blocks factorial scheme with four replicates. The treatments consisted of 5 doses of whey (0; 100; 200; 300 and 400 mg dm-3 N) associated with 3 doses de N-urea (0; 100 and 200 mg dm-3 N). Portions of 7 dm3 soil were incubated with lime and phosphate fertilizer and, 15 days before the end of incubation, the doses of whey were applied. After incubation, sowing followed by thinning (four plants/pot) were carried out, and the doses of N-urea were divided into 3 applications. Three grass cuts were made and, after the first cut, the treatments doses of whey and N-urea were reapplied. Whey fertilization increased the number of tillers, shoot dry matter production and crude protein of Mombaça grass, and the increases obtained varied as a funcion of the grass cycle and the N-ureea dose. The agronomic efficiency index of whey with N source in relation to urea was, on average, 69%. The whey increases production and improves the nutritional value of Mombaça grass, being an efficient alternative source of N for the forage.

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d’Apolito, Maria, Anna Colia, Enrica Manca, Massimo Pettoello-Mantovani, Michele Sacco, Angela Maffione, Michael Brownlee et Ida Giardino. « Urea Memory : Transient Cell Exposure to Urea Causes Persistent Mitochondrial ROS Production and Endothelial Dysfunction ». Toxins 10, n^o 10 (11 octobre 2018) : 410. http://dx.doi.org/10.3390/toxins10100410.

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Urea at post-dialysis levels induces increased ROS in a number of cell types. The aim of this study was to determine whether urea-induced production of ROS remains elevated after urea is no longer present, and, if it does, to characterize its origin and effects. Human arterial endothelial cells were incubated with 20 mM urea for two days, and then cells were incubated for an additional two days in medium alone. Maximal ROS levels induced by initial urea continued at the same level despite urea being absent. These effects were prevented by either MnSOD expression or by Nox1/4 inhibition with GKT13781. Sustained urea-induced ROS caused a persistent reduction in mtDNA copy number and electron transport chain transcripts, a reduction in transcription of mitochondrial fusion proteins, an increase in mitochondrial fission proteins, and persistent expression of endothelial inflammatory markers. The SOD-catalase mimetic MnTBAP reversed each of these. These results suggest that persistent increases in ROS after cells are no long exposed to urea may play a major role in continued kidney damage and functional decline despite reduction of urea levels after dialysis.

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Walsh, Olga S., et Kefyalew Girma. « Environmentally Smart Nitrogen Performance in Northern Great Plains’ Spring Wheat Production Systems ». International Journal of Agronomy 2016 (2016) : 1–12. http://dx.doi.org/10.1155/2016/8969513.

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Experiments were conducted in Montana to evaluate Environmentally Smart Nitrogen (ESN) as a nitrogen (N) source in wheat. Plots were arranged in a split-plot design with ESN, urea, and a 50%-50% urea-ESN blend at low, medium, and high at-seeding N rates in the subplot, with four replications. Measurements included grain yield (GY), protein (GP), and N uptake (GNU). A partial budget economic analysis was performed to assess the net benefits of the three sources. Average GY varied from 1816 to 5583 kg ha−1and grain protein (GP) content ranged from 9.1 to 17.3% among site-years. Urea, ESN, and the blend resulted in higher GYs at 3, 2, and 2 site-years out of 8 evaluated site-years, respectively. Topdressing N improved GY for all sources. No trend in GP associated with N source was observed. With GP-adjusted revenue, farmer would not recover investment costs from ESN or blend compared with urea. With ESN costing consistently more than urea per unit of N, we recommend urea as N source for spring wheat in Northern Great Plains.

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Baia, Luana, de Raddi, Carlos Pereira, de Carvalho et de Gaya. « Adsorption as alternative process in the preliminary production of automotive additive ». Chemical Industry and Chemical Engineering Quarterly 26, n^o 3 (2020) : 215–26. http://dx.doi.org/10.2298/ciceq190419038b.

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Nitrogenous contaminants in the diesel fraction are converted to NOx compounds in an automotive combustion chamber. Afterwards, they are reduced to nitrogen by catalytic reduction/oxidation reactions in presence of ammonia derived from a 32.5 wt.% urea solution. This process is named selective catalytic reduction (SCR). In Brazil, the urea solution for SCR is ARLA 32 and must comply with the limit content of 0.3 wt.% of biuret. However, the commercial Brazilian urea solution has an average biuret content of 0.5 wt.%. Thus, it is necessary to adjust the biuret content in urea solution to be used as ARLA 32, and adsorption is a low energy option. The objective of this study was to evaluate commercial adsorbents for removing biuret from solution of commercial urea to adjust it to the specification of ARLA 32. Two activated coals and one ion exchange resin were tested in adsorption assays, with best performances of both coals.

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Beres, B. L., R. J. Graf, R. B. Irvine, J. T. O’Donovan, K. N. Harker, E. N. Johnson, S. Brandt et al. « Enhanced nitrogen management strategies for winter wheat production in the Canadian prairies ». Canadian Journal of Plant Science 98, n^o 3 (1 juin 2018) : 683–702. http://dx.doi.org/10.1139/cjps-2017-0319.

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To address knowledge gaps around enhanced efficiency urea fertilizer efficacy for nitrogen (N) management, a study was designed to improve integrated nutrient management systems for western Canadian winter wheat producers. Three factors were included in Experiment 1: (i) urea type [urea, urea + urease inhibitor—Agrotain®; urea + urease and nitrification inhibitor—SuperU®, polymer-coated urea—Environmentally Smart Nitrogen® (ESN®), and urea ammonium nitrate (UAN)], (ii) application method (side-band vs. spring-broadcast vs. 50% side-band: 50% spring-broadcast), and (iii) cultivar (AC Radiant hard red winter wheat vs. CDC Ptarmigan soft white winter wheat). The Agrotain® and CDC Ptarmigan treatments were removed in Experiment 2 to allow for additional application methods: (i) fall side-band, (ii) 50% side-band — 50% late fall broadcast, (iii) 50% side-band — 50% early spring broadcast, (iv) 50% side-band — 50% mid-spring broadcast, and (v) 50% side-band — 50% late spring broadcast. CDC Ptarmigan produced superior grain yield and N utilization over AC Radiant. Grain yield and protein content were influenced by N form and application method. Split applications of N usually provided the maximum yield and protein, particularly with Agrotain® or SuperU®. An exception to the poor fall-application results was the SuperU® treatments, which produced similar yield to the highest-yielding treatments. The results suggest that split applications of N might be most efficient for yield and protein optimization when combined with an enhanced efficiency urea product, particularly with urease or urease + nitrification inhibitors, and if the majority of N is applied in spring.

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Mazinani, M., A. A. Naserian, M. Danesh Mesgaran et R. Valizadeh. « Effects of Adding Coated Urea on in vitro Gas Production of Dairy Cow ». Biosciences, Biotechnology Research Asia 15, n^o 2 (15 juin 2018) : 343–50. http://dx.doi.org/10.13005/bbra/2638.

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In this experiment the effects of different urea products (urea, Paraffin-sulfur Coated Urea (PSCU) and controlled release urea product (Optigen, Alltech Inc., Lexington, KY)) on rumen fermentation were investigated in dependence of different diet sources by using in vitro techniques. The experiment followed a completely randomized design using four N-source treatmentes (urea, Paraffin-sulfur Coated Urea, Optigen and canola meal) in four diets (wheat straw+ %3 isonitrogenous of each N-source, barley grain+ %3 isonitrogenous of each N-source, barley grain+ molasses+ %3 isonitrogenous of each N-source and formulated TMR diets for dairy cow+ %3 isonitrogenous), the cumulative gas production (96 hours) influenced by diets and N-source treatments was different, which was higher gas production in formulated TMR diets for dairy cow and least gas production in wheat straw. The result indicated that Optigen (90.82) and then PSCU (90.81) the highest gas producer in the formulated TMR diets for dairy cow and the canola meal (69.04) and urea (69.43) had the least gas production in wheat straw (P<005). As a result, little difference between treatments for slow-release urea with control (canola) was observed in animal experiments. And therefore reducing feed costs and increasing the efficiency of the rumen microorganisms can be used NPN sources as a replacement for part of dietary protein.

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Lam, Teresa, Mark McLean, Amy Hayden, Anne Poljak, Birinder Cheema, Howard Gurney, Glenn Stone et al. « A potent liver-mediated mechanism for loss of muscle mass during androgen deprivation therapy ». Endocrine Connections 8, n^o 5 (mai 2019) : 605–15. http://dx.doi.org/10.1530/ec-19-0179.

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Context Androgen deprivation therapy (ADT) in prostate cancer results in muscular atrophy, due to loss of the anabolic actions of testosterone. Recently, we discovered that testosterone acts on the hepatic urea cycle to reduce amino acid nitrogen elimination. We now hypothesize that ADT enhances protein oxidative losses by increasing hepatic urea production, resulting in muscle catabolism. We also investigated whether progressive resistance training (PRT) can offset ADT-induced changes in protein metabolism. Objective To investigate the effect of ADT on whole-body protein metabolism and hepatic urea production with and without a home-based PRT program. Design A randomized controlled trial. Patients and intervention Twenty-four prostate cancer patients were studied before and after 6 weeks of ADT. Patients were randomized into either usual care (UC) (n = 11) or PRT (n = 13) starting immediately after ADT. Main outcome measures The rate of hepatic urea production was measured by the urea turnover technique using 15N2-urea. Whole-body leucine turnover was measured, and leucine rate of appearance (LRa), an index of protein breakdown and leucine oxidation (Lox), a measure of irreversible protein loss, was calculated. Results ADT resulted in a significant mean increase in hepatic urea production (from 427.6 ± 18.8 to 486.5 ± 21.3; P < 0.01) regardless of the exercise intervention. Net protein loss, as measured by Lox/Lra, increased by 12.6 ± 4.9% (P < 0.05). PRT preserved lean body mass without affecting hepatic urea production. Conclusion As early as 6 weeks after initiation of ADT, the suppression of testosterone increases protein loss through elevated hepatic urea production. Short-term PRT was unable to offset changes in protein metabolism during a state of profound testosterone deficiency.

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Kabore, Steve, Ryusei Ito et Naoyuki Funamizu. « Effect of Formaldehyde/Urea Ratio on Production Rate of Methylene Urea from Human Urine ». Journal of Water and Environment Technology 14, n^o 2 (2016) : 47–56. http://dx.doi.org/10.2965/jwet.15-016.

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Isozaki, T., A. G. Gillin, C. E. Swanson et J. M. Sands. « Protein restriction sequentially induces new urea transport processes in rat initial IMCD ». American Journal of Physiology-Renal Physiology 266, n^o 5 (1 mai 1994) : F756—F761. http://dx.doi.org/10.1152/ajprenal.1994.266.5.f756.

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We reported that feeding rats 8% protein for 4 wk induces two new urea transport processes in initial inner medullary collecting ducts (IMCD); neither is present in rats fed 18% protein. In this study, we measured the time course of induction of these transporters in perfused initial IMCD segments from rats fed 8% protein. Net urea flux was induced after 3 wk, whereas vasopressin-stimulated passive urea permeability (P(urea)) was induced after 2 wk. 8-Bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) significantly increased P(urea)); adding vasopressin did not increase P(urea) further. In fact, there was no difference in vasopressin-stimulated cAMP production in initial or terminal IMCD segments from rats fed 18% or 8% protein, suggesting that the adaptive response was not due to increased cAMP production. Glucagon did not change cAMP production or P(urea). Specificity of the response was suggested because neither aldose reductase nor sorbitol dehydrogenase activity changed with feeding 8% protein. Thus 1) in initial IMCD segments, vasopressin-stimulated P(urea) is induced after 2 wk, but net urea flux requires 3 wk of feeding 8% protein; 2) this adaptation is not solely due to a higher rate of cAMP production; and 3) specificity of the adaptive response is suggested because activities of enzymes responding to decreases in concentrating ability are unchanged. These results suggest that two distinct urea transporters may be involved in the adaptation to a low-protein diet.

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BAKHSH, A., I. BASHIR, H. U. FARID et S. A. WAJID. « USING CERES-WHEAT MODEL TO SIMULATE GRAIN YIELD PRODUCTION FUNCTION FOR FAISALABAD, PAKISTAN, CONDITIONS ». Experimental Agriculture 49, n^o 3 (26 février 2013) : 461–75. http://dx.doi.org/10.1017/s0014479713000185.

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SUMMARYUsing computer simulation model as a management tool requires model calibration and validation against field data. A three-year (2008–2009 to 2010–2011) field study was conducted at the Postgraduate Agricultural Research Station of the University of Agriculture, Faisalabad, Pakistan, to simulate wheat grain yield production as a function of urea fertilizer applications using Crop Environment REsource Synthesis (CERES)-Wheat model. The model was calibrated using yield data for treatment of urea fertilizer application at the rate of 247 kg-urea ha−1 during growing season 2009–2010 and was validated against independent data sets of yield of two years (2008–2009 and 2010–2011) for a wide variety of treatments ranging from no urea application to 247 kg-urea ha−1 application. The model simulations were found to be acceptable for calibration as well as validation period, as the model evaluation indicators showed a mean difference of 8.9%, ranging from 0.05 to 15.38%, root mean square error of 356 having its range from 242 to 471 kg ha−1, against all observed grain yield data. The scenario simulations showed maximum grain yield of 4100 kg ha−1 for 350 kg-urea ha−1 in 2008–2009; 4600 kg ha−1 for 300 kg-urea ha−1 in 2009–2010 and 5200 kg ha−1 for 340 kg-urea ha−1 in 2010–2011. Any further increase in urea application resulted in decline of grain yield function. These results show that model has the ability to simulate effects of urea fertilizer applications on wheat yield; however, the simulated maximum grain yield data need field-based verification.

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Sitompul, J. P. « Studi Produksi Hidrasin VIA Proses Urea ». REAKTOR 9, n^o 2 (19 juin 2017) : 20. http://dx.doi.org/10.14710/reaktor.9.2.20-25.

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The use of hydrazine,N2H4 becomes very broad nowadays, in the production of polymer such as automobile air bags, in pharmacy, and in the water treatment for oxygen scavenge. Three commercial processes are available for hydrazine production , i.e. via Rasching-Olin, Ketazin, and Urea process. The operating condition for the later process is very mild compared to with the other two processes and hence requires simple processing equipments. This paper concerns with the kinetic study on production and on the effect of deactivator/ inhibitor during hydrazine bench-scale production via Urea process. Operating condition are at 1 bar and at temperature range 5-100 0C. The yield of the hydrazine and its concentration with varying reactants, NaOH, hypochlorite, and urea during the cource of reaction are presented. Futher, the effect of gelatin as the deactivator toward hydrazine yield is futher examined. A kinetic model is proposed and used to predict yield of hydrazine. The predicted yield is in close agreement with the experimental yield.Keywords : hydrazine, bench-scale production, kinetic model, oxygen scavenger, inhibitor, geltine

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Wu, Kaikuo, Zhe Zhang, Liangshan Feng, Wei Bai, Chen Feng, Yuchao Song, Ping Gong, Yue Meng et Lili Zhang. « Effects of Corn Stalks and Urea on N2O Production from Corn Field Soil ». Agronomy 11, n^o 10 (4 octobre 2021) : 2009. http://dx.doi.org/10.3390/agronomy11102009.

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Returning corn stalks to the field is an important and widely used soil management practice which is conducive to the sustainable development of agriculture. In this study, the effects of corn stalks and urea on N2O production in corn field soil were investigated through a 21-day incubation experiment. This study showed that increasing amounts of urea added to soil with a history of corn cultivation leads to increasing overall N2O emissions, by increasing both the intensity and the duration of emissions. Although N2O production was affected primarily by urea-derived NH4+-N and NO3−-N, its main source was native soil nitrogen, which accounted for 78.5 to 94.5% of N2O. Returning corn stalk residue to the field reduced the production of N2O, and the more urea was applied, the stronger the effect of corn residue on reducing N2O emissions. Combining the application of corn stalks and urea could reduce the concentration of NH4+-N and NO3−-N derived from urea, and then reduce the substrate required for N2O production in nitrification and denitrification processes. In addition, the combined application of corn stalks and urea could effectively inhibit the abundance of key N2O-producing genes AOA amoA, nirS and nirK.

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