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Urea

About: Urea is a research topic. Over the lifetime, 21394 publications have been published within this topic receiving 382444 citations. The topic is also known as: carbamide & carbonic acid diamide.


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TL;DR: In this article, Nitrous oxide, nitric oxide and denitrification losses from an irrigated soil amended with organic fertilizers with different soluble organic carbon fractions and ammonium contents were studied in a field study covering the growing season of potato.
Abstract: Nitrous oxide, nitric oxide and denitrification losses from an irrigated soil amended with organic fertilizers with different soluble organic carbon fractions and ammonium contents were studied in a field study covering the growing season of potato ( Solanum tuberosum ) Untreated pig slurry (IPS) with and without the nitrification inhibitor dicyandiamide (DCD), digested thin fraction of pig slurry (DTP), composted solid fraction of pig slurry (CP) and composted municipal solid waste (MSW) mixed with urea were applied at a rate of 175 kg available N ha −1 , and emissions were compared with those from urea (U) and a control treatment without any added N fertilizer (Control) The cumulative denitrification losses correlated significantly with the soluble carbohydrates, dissolved N and total C added Added dissolved organic C (DOC) and dissolved N affected the N 2 O/N 2 ratio, and a lower ratio was observed for organic fertilizers than from urea or unfertilized controls The proportion of N 2 O produced from nitrification was higher from urea than from organic fertilizers Accumulated N 2 O losses during the crop season ranged from 369 to 731 kg N 2 O–N ha −1 for control and urea, respectively, whereas NO losses ranged from 0005 to 024 kg NO–N ha −1 , respectively Digested thin fraction of pig slurry compared to IPS mitigated the total N 2 O emission by 48% and the denitrification rate by 33%, but did not influence NO emissions Composted pig slurry compared to untreated pig slurry increased the N 2 O emission by 40% and NO emission by 55%, but reduced the denitrification losses (34%) DCD partially inhibited nitrification rates and reduced N 2 O and NO emissions from pig slurry by at least 83% and 77%, respectively MSW+U, with a C:N ratio higher than that of the composted pig slurry, produced the largest denitrification losses (333 kg N ha −1 ), although N 2 O and NO emissions were lower than for the U and CP treatments This work has shown that for an irrigated clay loam soil additions of treated organic fertilizers can mitigate the emissions of the atmospheric pollutants NO and N 2 O in comparison with urea

164 citations

Journal ArticleDOI
TL;DR: It is suggested that PAG may replace urea as a waste nitrogen product when phenylbutyrate is administered at a dose that yields PAG nitrogen excretion equal to 40–44% of a low nitrogen intake.
Abstract: Phenylacetylglutamine (PAG), the amino acid acetylation product of phenylacetate (or phenylbutyrate after β-oxidation) was evaluated as a waste nitrogen product in patients with inborn errors of urea synthesis. A boy with carbamyl phosphate synthetase deficiency receiving a low nitrogen intake excreted SO-90% of administered phenylacetate or phenylbutyrate as PAG. The amount of PAG nitrogen excreted varied from 38–44% of his dietary nitrogen, similar to the relationship between urea nitrogen and dietary nitrogen found in normal subjects receiving low dietary nitrogen. With few exceptions, neither phenylacetate nor phenylbutyrate accumulated in plasma. Treatment with relatively high dose phenylacetate or phenylbutyrate (0.5–0.6 g/kg/d) resulted in normal daytime levels of glutamine. These data suggest that PAG may replace urea as a waste nitrogen product when phenylbutyrate is administered at a dose that yields PAG nitrogen excretion equal to 40–44% of a low nitrogen intake.

163 citations

Journal ArticleDOI
TL;DR: Simulation results reveal the potential importance of the indirect effects of cosolvents in protein denaturation or structure protection, particularly through modifying of the water-amide interactions.
Abstract: The effects of urea, tetramethyl urea (TMU), and trimethylamine N-oxide (TMAO) on the structure and dynamics of aqueous solutions are studied using molecular dynamics simulations. It was found that urea has little effects on the water−water hydrogen-bond length and angle distributions except that it induces a slight collapse of the second shell in the hydrogen-bonding network. TMU and TMAO both strengthen the individual hydrogen bonds and significantly slow the orientational relaxation of water, but have opposite effects on the second shell structure of the hydrogen-bonding network: TMU distorts while TMAO enhances the tetrahedral water structure. Furthermore, TMAO significantly weakens the interactions between the amide carbonyl group and the water molecules, while TMU and urea both strengthen these interactions, with the effect of urea being much less significant than that of TMU. These conclusions are supported by molecular dynamics simulations of three different systems: a model amide compound CH3−NH−...

163 citations

Journal ArticleDOI

163 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,000
20221,982
2021433
2020502
2019589
2018557