Topic
Ammonia
About: Ammonia is a research topic. Over the lifetime, 16217 publications have been published within this topic receiving 271940 citations. The topic is also known as: NH3 & azane.
Papers published on a yearly basis
Papers
More filters
TL;DR: Experimental evidence is presented that the threshold pressure of ~120 GPa induces in molecular ammonia the process of autoionization to yet experimentally unknown ionic compound--ammonium amide, opening new possibilities for studying molecular interactions in hydrogen-bonded systems.
Abstract: Ionization of highly compressed ammonia has previously been predicted by computation. Here, the authors provide experimental evidence for this autoionization process at high pressures, showing the transformation of molecular ammonia into ammonium amide.
3,638 citations
TL;DR: The results suggest that addition of non-protein N supplements to ruminant rations are warranted only if the prevailing concentration of ruminal ammonia is less than 50 mg NH3-N/l ruminal fluid.
Abstract: 1. The effect of ammonia concentration on microbial protein production was determined in continuous-culture fermentors charged with ruminal contents obtained from steers fed on either a protein-free purified diet, a maize-based all-concentrate diet, or a forage–concentrate (23:77) diet. Urea was infused into the fermentors to maintain various concentrations of ammonia in the incubating mixtures.2. Under nitrogen-limiting conditions, microbial protein yield measured as tungstic acid-precipitable N (TAPN) increased linearly with supplementary urea until ammonia started to accumulate in the incubating ingesta. Increasing the ammonia concentration beyond 50 mg NH3-N/l had no effect on microbial protein production.3. The molar proportions of volatile acids produced were not affected by the level of urea supplementation. Total acid production was decreased slightly under N-limiting conditions, but not to the same extent as microbial protein production.4. Estimated yield of microbial dry matter/mol ATP produced averaged 15·6 when non-limiting N as urea was provided with the purified diet.5. These results suggest that addition of non-protein N supplements to ruminant rations are warranted only if the prevailing concentration of ruminal ammonia is less than 50 mg NH3-N/l ruminal fluid.
1,731 citations
TL;DR: A critical evaluation of the literature data on the ammonia–water equilibrium system has been carried out and results of calculations of values of pKa at different temperatures and of percent of NH3 in aqueous ammonia solutions of zero salinity as a function of pH and temperature are presented.
Abstract: The toxicity of ammonia to fishes has been attributed to the un-ionized ammonia chemical species present in aqueous solution Because the percent of total ammonia present as un-ionized ammonia (NH3) is so dependent upon pH and temperature, an exact understanding of the aqueous ammonia equilibrium is important for toxicity studies A critical evaluation of the literature data on the ammonia–water equilibrium system has been carried out Results of calculations of values of pKa at different temperatures and of percent of NH3 in aqueous ammonia solutions of zero salinity as a function of pH and temperature are presented
1,329 citations
TL;DR: The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively and the anammox process was completely inhibited by nitrite concentrations higher than 0.1 g of nitrogen per liter.
Abstract: The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively. The physiological pH and temperature ranges were 6.7 to 8.3 and 20 to 43°C, respectively. The affinity constants for the substrates ammonium and nitrite were each less than 0.1 mg of nitrogen per liter. The anammox process was completely inhibited by nitrite concentrations higher than 0.1 g of nitrogen per liter. Addition of trace amounts of either of the anammox intermediates (1.4 mg of nitrogen per liter of hydrazine or 0.7 mg of nitrogen per liter of hydroxylamine) restored activity completely.
1,274 citations
TL;DR: The denitrification pathway in this cycle, that is, the conversion of nitrate to dinitrogen, is employed by certain bacteria to produce ATP anaerobically and gain energy for cell growth.
Abstract: After carbon, hydrogen, and oxygen, nitrogen is the next most abundant element in the human body. Inorganic and organic compounds of nitrogen feature prominently in many biological and environmental, as well as industrial, processes. In nature, the inorganic compounds of nitrogen are controlled by a reaction cycle called the nitrogen cycle (Figure 1).1 The denitrification pathway in this cycle, that is, the conversion of nitrate to dinitrogen, is employed by certain bacteria to produce ATP anaerobically and gain energy for cell growth. All organisms use ammonia as one of the starting building blocks for the synthesis of amino acids, nucleotides, and many other important biological compounds. Nitric oxide is * Corresponding author. E-mail: m.koper@chem.leidenuniv.nl. † Present address: Energy research Centre of The Netherlands (ECN), P.O. Box 1, 1755 ZG Petten, The Netherlands. ‡ Present address: Research, Development & Innovation, AkzoNobel Chemicals bv, Velperweg 76, P.O. Box 9300, 6800 SB Arnhem, The Netherlands. Chem. Rev. 2009, 109, 2209–2244 2209
992 citations