Topic
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, the progress in urea based fuel cells and electrocatalysts for urea oxidation is reviewed, and the main limitation of urea fuel cells is the relative low power density due to the sluggish anode reaction.
Abstract: Urea is a new member of hydrogen-storage materials for low-temperature fuel cells. It avoids issues of toxicity and safety compared to ammonia and hydrazine. The main limitation of urea fuel cells is the relative low power density due to the sluggish anode reaction. Rapid advances in nano-catalysts for urea electrooxidation have been achieved in order to lower overpotential and improve activity. Urine, as a natural resource of urea, is also an environmental pollutant. Most technologies of treating urine with self-generation electricity are based on microbial fuel cells. However, microbes are only able to utilize the organic substrates rather than urea in urine. Chemical fuel cells in contrast directly oxidize urea to nitrogen gas and removed from urine. Thus urea fuel cells have been used as an alternative method to treat urine. In the paper, the progress in urea based fuel cells and electrocatalysts for urea oxidation is reviewed.
167 citations
Journal Article•
TL;DR: It was calculated that protein production in the rumen at the highest nitrogen intake was less than the potential production from the energy supplied to the microorganisms.
Abstract: Direct measurement has been made of the daily production of microbial protein in the rumen. When sheep were fed on a virtually protein-free purified diet, increases in the intake of nitrogen from 2 to 9 g/day increased linearly the production of protein in the rumen from 32.5 to 50.0 g/day. There was no further increase in protein production when the nitrogen intake was raised to 16 g/day. The amount of total nitrogen flowing out of the rumen showed a net increase over that ingested at daily nitrogen intakes of 2 and 4 g, no change at 9 g, and a substantial net loss at 16 g. At the lowest nitrogen intake at least 4 g recycled nitrogen was utilized by the rumen microorganisms daily. The yield of protein from the ruminal fermentation increased from 9.1 g/100 g organic matter digested in the rumen when nitrogen was most limiting, to 13.3 g/100 g when nitrogen was in excess of requirements. It was calculated that protein production in the rumen at the highest nitrogen intake was less than the potential production from the energy supplied to the microorganisms. Possible limiting factors are discussed.
167 citations
167 citations
TL;DR: The protein metabolic response to burn injury was assessed in 17 children and the protein kinetic response did not correlate with changes in the metabolic rate since resting energy expenditure was significantly increased above predicted levels during the acute and flow phases, and returned to normal in convalescence.
Abstract: The protein metabolic response to burn injury was assessed in 17 children aged 7.1 ± 1.1 years (mean ± SEM) and a mean burn size of 65 ± 7% total body surface area (TBSA) during the acute, flow, convalescent, and recovery phases. Stable isotopes of leucine, valine, lysine, and urea were infused in postabsorptive patients in order to measure protein kinetics. The absolute rate of protein breakdown was assessed from the plasma flux of the essential amino acids (EAA), and the rate of urea production (Ra urea) was used as an index of net protein catabolism. Compared to values obtained in recovered patients, the plasma fluxes of all three EAAs were significantly increased ( P P
166 citations
TL;DR: The global warming potential was lower with the inhibitors (except hydroquinone) as compared to urea alone, suggesting that these substances could be used for mitigating greenhouse gas emission from the rice-wheat systems.
166 citations