A series of structurally diverse spiro 1,3-oxazines were conveniently prepared from three-component reaction conjugated imines, dialkyl acetylenedicarboxylates (DAAD), and N,N'-disubstituted parabanic acids in dry dichloromethane without catalyst. Initially, various imines synthesized aniline derivatives with cinnamaldehyde. Subsequently, DAAD N,N'-substituted led to mixture the corresponding s...

Investigations using ammonium citrate-(15)N and urea-(15)N showed that children in the acute stage of kwashiorkor and marasmus receiving a diet of adequate protein content retained a considerable percentage of the label from both compounds. Excretion of both total (15)N and urea-(15)N was subnormal and elimination was virtually completed 36 hr after administration of the isotope. During recover...

Urea synthesized commercially and formed naturally as a by-product of cellular metabolism is an important source of nitrogen (N) for primary producers in aquatic ecosystems. Although urea is usually present at ambient concentrations below 1 μM-N, it can contribute 50% or more of the total N used by planktonic communities. Urea may be produced intracellularly via purine catabolism and/or the ure...

low nitrogen (n) use efficiency is considered to be one of the major problems in wheat production fields all over the world. this experiment was conducted to evaluate the effects of nitrification inhibitor (ni) 3, 4- dimethylpyrazole phosphate (dmpp) on the yield and nitrogen use efficiency of spring wheat (triticum aestivum l.) cv. bahar during 2011 at shahrekord university. a factorial experi...

N-Benzyl- and N-2°-alkylpyridinium salts were engaged in visible-light-driven, photoredox-induced radical-cationic three-component couplings with N-methylmaleimide acrylonitrile as radical acceptors, combination 1,1-diarylethylenes donor alkenes. These multicomponent coupling reactions could be achieved under mild conditions, high efficiency, to furnish diverse 3,4-disubstituted pyrrolidin-2,5-...

Two experiments were conducted to assess effects of endophyte treatments (Exp. 1), forage species (Exp. 2), and supplementation (Exp. 2) on urea production, excretion, and recycling in beef steers. Infusion of (15,15)N-urea and enrichment of urea in urine samples were used to calculate urea-N entry and recycling to the gut. Acceptably stable enrichment of (15)N-urea in urine was obtained after ...