Showing papers on "Ammonia published in 1977"

Ammonia in the human airways: neutralization of inspired acid sulfate aerosols.

Abstract: In the human being, expired ammonia concentrations from 7 to 520 micrograms per cubic meter are controlled by the last airway segment traversed by the air, and such concentrations are higher in the mouth than nose. Inspired submicrometric sulfuric acid aerosol at a mass concentration of 600 +/- 100 micrograms per cubic meter was found to be an ammonium salt with an average ammonium to sulfate molar ratio of greater than or equal to 1, when sampled within 0.5 second after exhalation.

Inhibition of nitrate uptake by ammonia in a blue-green alga, Anabaena cylindrica

Abstract: Ammonia at concentrations above 1×10-5 M inhibits uptake of nitrate in the nitrogen-fixing blue-green alga, Anabaena cylindrica. This inhibition takes place both in the light and in the dark. The rate of nitrate uptake is stimulated by light. Addition of relatively high concentrations of nitrate (1–10 mM) reversibly inhibits ammonia uptake. FCCP, an uncoupler of phosphorylation, inhibits both nitrate and ammonia uptake. Ammonia may inhibit nitrate uptake by reducing the supply of energy (ATP) for active nitrate transport.

Field Measurements of Ammonia Volatilization from Surface Applications of Ammonium Salts to a Calcareous Soil1

Abstract: Many laboratory experiments have been conducted to study ammonia volatilization from N fertilizers, but few experiments have been conducted under field conditions. The objective of this study was to evaluate ammonia volatilization in the field from ammonium sulfate and ammonium nitrate applied to the surface of a calcareous soil, Houston Black Clay, that belongs to the fine, montmorillonitic, thermic family of Udic Pellusterts. Volatilization was evaluated indirectly by measuring N uptake by Coastal bermudagrass (Cynodon dactylon L.) and directly by measuring ammonia as it volatilized. In the field plot study, estimated losses ranged from 3 to 10% of the applied N for ammonium nitrate, from 36 to 45% of the applied N for pelleted ammonium sulfate, and from 25 to 55% of the applied N for liquid ammonium sulfate at rates of 140 and 280 kg N/ha. Direct measurements of ammonia losses from pelleted ammonium sulfate were 47, 43, 59, and 50% of the applied N in late summer, 1975, and 39, 30, 27, and 35% of the applied N in spring, 1976, at rates of 33, 66, 140, and 280 kg N/ ha. The lower loss of ammonia in the spring was apparently in response to lower soil temperatures at that time. Consistent diurnal fluctuations in ammonia losses occurred at both times. These fluctuations corresponded closely with daily fluctuations in the atmospheric relative humidity. These results agree with earlier laboratory studies in that ammonium sulfate loses considerably more ammonia than ammonium nitrate when applied to the surface of a calcareous clay soil.

Nitrate formation in atmospheric aerosols

Abstract: Equilibrium nitrate levels in aqueous solution in the presence of sodium chloride, nitric oxide, nitrogen dioxide, sulfur dioxide, carbon dioxide, ammonia, and sulfuric acid are calculated. Nitrate levels in solution are of the order of those observed in the atmosphere when the gaseous concentrations are at typical urban levels. Sulfate levels in such solutions are predicted to be relatively low in the absence of oxidation catalysts. When sulfate formation is assumed to occur by gas-phase oxidation of sulfur dioxide to sulfuric acid followed by absorption of the sulfuric acid in aerosols, predicted nitrate and sulfate size distributions are in qualitative agreement with those observed in the atmosphere.

Inhibition of conditions arising from microbial production of ammonia

Abstract: Methods, compositions and products are described which inhibit the development of undesirable conditions arising as a result of microbial formation of ammonia from urea in excreted urine. Amino acid compounds are employed.

The origin and fate of salivary urea and ammonia in man.

Abstract: 1. Saliva obtained from the parotid duct of normal and uraemic subjects had an average urea concentration of 86% of the plasma concentration whereas in mixed saliva obtained from the mouth the urea concentration was only 31% of the plasma concentration. Ammonia concentrations were low or unmeasurable in parotid saliva but varied between 0·6 and 26 mmol/kg in oral saliva, showing a positive correlation with the plasma urea concentration. 2. The urea in samples of mixed oral saliva incubated at 37°C disappeared by 290 min. Ammonia steadily increased during incubation; within the first 100 min, the increase could be largely accounted for by bacterial hydrolysis of urea, but later non-urea sources became relatively more important. 3. These findings suggest that the ammonia in mixed oral saliva is derived by bacterial hydrolysis of urea within the mouth. However, the concentration of ammonia plus urea nitrogen in oral saliva was only 76% of the urea nitrogen concentration of parotid saliva, which suggests that some ammonia is lost from the mouth by buccal absorption or by volatilization. 4. To assess the role of non-ionic diffusion of ammonia through the buccal mucosa, we studied the effect of pH on the disappearance of ammonia from buffered solutions retained in the mouth. Ammonia concentrations fell more rapidly at pH 9 than at pH 7, as also did those of hydrazine, a non-volatile analogue of ammonia which is known to be absorbed through other mucosae by non-ionic diffusion. These findings suggest that salivary ammonia is reabsorbed passively through the oral mucosa in the un-ionized phase.

Ammonia volatilization from a flooded tropical soil

Abstract: Ammonia volatilization, which follows upon the application of nitrogenous fertilizers to a flooded tropical soil, was directly measured in the greenhouse and in the field. Most of the ammonia volatilization losses occurred during the first 9 days after nitrogen application. Ammonia volatilization increased markedly with increases in soil pH. Nitrogen losses from ammonium sulfate applied to soils whose pH values were below 7.5 were very small. The losses from urea were much greater than those from ammonium sulfate. Mixing the fertilizer materials with the puddled soil reduced the losses. Ammonia losses from flooded soil were larger than from dry soil, and drying of a flooded soil reduced the duration and magnitude of ammonia volatilization. It is suggested that only a small amount of nitrogen is being lost through ammonia volatilization from many lowland rice soils. re]19750820

Polarographic Study of Ammonia Assimilation by Isolated Chloroplasts

Abstract: Illuminated pea ( Pisum sativum ) chloroplasts catalyze (ammonia plus α-ketoglutarate [α-KG])-dependent O 2 evolution at rates which are commensurate with other estimates of the flux of assimilated nitrogen (mean of eight determinations, 8.3 μmole per mg chlorophyll per hour, sd 2.4). The reaction was usually initiated with 1 mm ammonia after preincubating chloroplasts in the presence of α-KG, ADP, pyrophosphate, and MgCl 2 . Progressive increases in ammonia concentration gave V max /2 at 0.2 mm (approximately) and V max at about 1 mm. Higher concentrations were inhibitory; at 7 mm the rate was again about V max /2. The highest ratio of O 2 evolved per mol of ammonia supplied was 0.36. The (ammonia plus α-KG)-dependent reaction was inhibited by methionine sulfoximine, azaserine, and aspartate in the presence of amino-oxyacetate but not by amino-oxyacetate alone and not by l-glutamate. The rate of O 2 evolution in the presence of 1 mm ammonia and 2.5 mm α-KG was increased only slightly by addition of 5 mm glutamine. Similarly, the rate of O 2 evolution in the presence of 5 mm glutamine and 2.5 mm α-KG was increased only slightly by addition of 1 mm ammonia. The results are attributed to the incorporation of ammonia via glutamine synthetase and reductive transamination of the glutamine formed by photosynthetically coupled glutamate synthase using α-KG as the amino acceptor. Several lines of evidence rule out the possibility that photosynthetically coupled glutamate dehydrogenase is involved.

Amino Acid Metabolism of Pea Leaves Labeling Studies on Utilization of Amides

Abstract: Short term (2-hour) incorporation of nitrogen from nitrate, glutamine, or asparagine was studied by supplying them as unlabeled (14N) tracers to growing pea (Pisum sativum L.) leaves, which were previously labeled with 15N, and then following the elimination of 15N from various amino components of the tissue. Most components had active and inactive pools. Ammonia produced from nitrate was assimilated through the amide group of glutamine. When glutamine was supplied, its nitrogen was rapidly transferred to glutamic acid, asparagine, and other products, and there was some transfer to ammonia. Nitrogen from asparagine was widely distributed into ammonia and amino compounds. There was a rapid direct transfer to glutamine, which did not appear to involve free ammonia. Alanine nitrogen could be derived directly from asparagine, probably by transamination. Homoserine was synthesized in substantial amounts from all three nitrogen sources. Homoserine appears to derive nitrogen more readily from asparagine than from free aspartic acid. A large proportion of the pool of γ-aminobutyric acid turned over, and was replenished with nitrogen from all three supplied sources.

Influence of aldosterone on renal ammonia production

Abstract: Administering D-aldosterone, 7 microgram 100 g-1, to rats results in a marked rise in ammonium excretion and metabolic alkalosis. Increased ammonium excretion is not related to either a significant elevation in potassium excretion nor to hypokalemia. Consequently, potassium depletion does not appear to be the causative factor in the aldosterone-stimulated ammonium excretion. Isolated kidneys from aldosterone-treated rats, perfused with 1 mM L-glutamine, produced twice as much ammonia from glutamine as did controls. Ammonia production per glutamine extracted increased from 1.33 +/- 0.07 in control to 1.79 +/- 0.08 in kidneys from hormone-treated rats, suggesting stimulation of the mitochondrial glutaminase I-glutamate dehydrogenase pathway; this was supported by a proportional rise in production of glucose and CO2, end products of glutamine's carbon skeleton. Consequently, aldosterone-stimulated renal ammonia production, by specifically activating the mitochondrial pathway, leads to the elimination of hydrogen ions in the form of urinary ammonium excretion and an ensuing metabolic alkalosis.

Catalyst composition with support comprising titanium oxide and clay mineral for vapor phase reduction of nitrogen oxides

Abstract: A catalyst composition for the vapor phase reduction of nitrogen oxides with ammonia, which consists essentially of a non-noble transition metal compound supported on a shaped carrier comprising a titanium oxide and a clay mineral having an average particle size of 0.1 to 100 microns. The shaped carrier preferably contains an additional component which is an inorganic fibrous material, silica hydrogel, silica sol, or a mixture of at least two of these. An exhaust gas containing nitrogen oxides is treated, with a high percent NO removal, by contacting it with the catalyst composition in the presence of ammonia gas at 200 to 600° C.

Nitrate determination by reduction to ammonia and gas-phase ultraviolet absorption spectrometry

Abstract: Nitrate can be rapidly reduced to ammonia by the action of titanium(III) sulphate, even at room temperature. Subsequent displacement of the ammonia by a current of air enables the gas-phase molecular absorbance of the ammonia to be measured and thus provides a sensitive and selective method for the determination of nitrate. Ions which affect the reduction of nitrate by titanium(III) salts interfere with the method and must be removed if present in large amounts.

Theoretical calculations on the influence of the inorganic nitrogen source on parameters for aerobic growth of microorganisms

Abstract: The amount of ATP required for the formation of microbial cells growing in a minimal medium with various nitrogen sources was calculated. In a glucose-mineral salts medium 28.8 g cells can be formed per mole ATP with ammonia and 23.1 for growth with nitrate. For growth with molecular nitrogen 11.1; 8.7; 7.1 and 6.0 g cells can be formed per mole ATP for ATP/N2 ratios of 12, 18, 24 and 30 respectively. A method is given for the calculation of Ysub, YO2 and Yc02 values for aerobic growth with glucose, succinate or methanol and various nitrogen sources. In this method use is made of the elementary composition of the cells and of mass balance equations. As an assimilation equation: C6H12O7 + 1.4 HNO3 + 6.85 “H2” → C6H10.84N1.4O3.07 + 8.13 H2O is given for growth ofParacoccus denitrificans with gluconate and nitrate. From this equation and the molar growth yield for gluconate the oxygen uptake, carbon dioxide evolution and the YO2 value can be calculated. A very good agreement between the calculated values and the experimental values was obtained. For the calculation of the ATP production it is essential to know the number of phosphorylation sites in the respiratory chain. Calculations are given for 2 (sites I + II) and 3 phosphorylation sites. The molar growth yields for growth with nitrate and nitrogen are much smaller than that for growth with ammonia. The YO2 values for growth with glucose and nitrate are higher (with 2 sites) or somewhat smaller (with 3 sites) than for growth with ammonia. The YO2 values for growth with nitrogen are always very low. The calculations show that especially YO2 is very dependent on the number of phosphorylation sites. For growth with methanol YCO2 is strongly dependent on the nature of the assimilation pathway for methanol and on the nitrogen source. The molar growth yields for growth with glucose, succinate or methanol and nitrogen are about the same as when nitrate is the nitrogen source for organisms with 3 phosphorylation sites. The theoretical efficiency of nitrogen fixation in grow-ing cells is much lower (dependent on the ATP/N2 ratio) than that in nongrowing cells.

Transport of urea at low concentrations in Chlamydomonas reinhardi.

Abstract: Urea transport into the unicellular green alga Chlamydomonas reinhardi was investigated to further our understanding of controls operating on urea catabolism in this organism Transport into cells grown with acetate and deprived of ammonia is a saturable process, mediated by at least two systems operating maximally at different external urea concentrations The lower concentration system, with an apparent Km for urea of 51 micron, was the object of detailed study Transport of urea from a saturating concentration (57 micron) into ammonia- and acetate-grown cells freshly suspended in ammonia-limited medium was not detected Upon further culturing in the absence of ammonia, derepression occurred with transport ability, first appearing at about 1 h , reaching a maximum at about 2 h, and maintaining this maximum at least 5 h In contrast to this, CO2-grown cells became derepressed more slowly, and maximum transport ability was not maintained Addition of ammonia or methylamine (5 mM) during nitrogen deprivation prevented further increases in transport ability and caused loss of previously acquired transport ability Cycloheximide (10 microng/ml) had a similar effect Energy uncouplers or dark, anaerobic conditions depressed transport By these criteria, transport from low urea concentrations is mediated by a process that requires protein synthesis and activation by cellular energy, and the process has a rapid rate of turnover and of deactivation by ammonia

Ion exchange materials to increase consumption of non-protein nitrogen by ruminants

Abstract: In the feeding of non-protein nitrogen (NPN) compounds such as urea to ruminants, the NPN compound is decomposed to ammonia in the rumen. To mitigate against toxic effects of the resulting high ammonium ion content of the ruminal fluid, a zeolite, or crystalline alumino silicate cation exchange material, is introduced into the rumen and maintained therein so that ammonium ions formed by NPN decomposition are accumulated during the post-feeding fermentation period, and later released by the regenerant action of saliva entering the rumen during rumination.

Process for removing nitrogen oxides using ammonia as a reductant and sulfated metallic catalysts

Abstract: Nitrogen oxides are removed from flue gas evolving from stationary sources and containing the nitrogen oxides through reduction of nitrogen oxides to nitrogen by passing the flue gas over a catalyst of metal compounds containing oxysulfur compounds in the presence of an ammonia gas