Showing papers on "Ammonia published in 1969"

Nitrogen Metabolism of Lemna minor. II. Enzymes of Nitrate Assimilation and Some Aspects of Their Regulation

Abstract: In L. minor grown in sterile culture, the primary enzymes of nitrate assimilation, nitrate reductase (NR), nitrite reductase (NiR) and glutamate dehydrogenase (GDH) change in response to nitrogen source. NR and NiR levels are low when grown on amino acids (hydrolyzed casein) or ammonia; both enzymes are rapidly induced on addition of nitrate, while addition of nitrite induces NiR only. Ammonia represses the nitrate induced synthesis of both NR and NiR. NADH dependent GDH activity is low when grown on amino acids and high when grown on nitrate or ammonia, but the activities of NADPH dependent GDH and Alanine dehydro-genase (AIDH) are much less affected by nitrogen source. NADH-GDH and AIDH are induced by ammonia, and it is suggested that these enzymes are involved in primary nitrogen assimilation.

Catalytic hydrogenation of aromatic nitrogen containing compounds over alkali moderated ruthenium

Abstract: ORGANIC AROMATIC NITROGEN CONTAINING COMPOUNDS, SUCH AS P-PHENYLENEDIAMINE OR 4,4''-METHYLENEDIANILINE, CAN BE HYDROGENATED BY ADMIXING THE COMPOUND WITH HYDROGEN AT A HYDROGEN PARTIAL PRESSURE OF AT LEAST 200 PSI, A TOTAL PRESSURE OF FROM 200 PSI TO 15,000 PSI, A TEMPERATURE IN THE RANGE OF FROM 100*C TO 300*C, IN THE PRESENCE OF FROM O% TO 200% BY WEIGHT, BASED ON THE WEIGHT OF THE COMPOUND TO BE HYDROGENATED, OF ADDED AMMONIA, AND IN THE PRESENCE OF FROM 0001% TO 10% BY WEIGHT, BASED ON THE COMPOUND TO BE HYDROGENATED AND CALCULATED AS METALLIC OF A RUTHENIUM CATALYST SUPPORTED ON AN INERT CARRIER, SAID CATALYST BEING ALKALI MODERATED WITH FROM 01% TO 15% OF A BASIC METAL COMPOUND CALCULATED AS THE ALKALI METAL

Biosynthesis of amino acids

Abstract: This chapter discusses the biosynthesis of amino acids. Many bacteria have the ability to grow with nitrate as the sole nitrogen source, which means that nitrate must be reduced to ammonia, an eight-electron change in oxidation state. The enzymes of nitrate assimilation are distinct from those involved in nitrate respiration and are differentiated operationally by the fact that enzymes of nitrate assimilation are pyridine nucleotide-linked while the enzymes of nitrate respiration are connected to the cytochrome system. The first step in nitrate assimilation is the reduction of nitrate to nitrite. The reduction of molecular nitrogen to ammonia is a process principally of microorganisms and occurs in bacteria of such widely diverse genera as Clostridium , Azotobacter , the symbiotic Rhizobium , and photosynthetic Rhodospirillum and Chromatium . Ammonia is the form of inorganic nitrogen most readily assimilated by bacteria able to grow with an inorganic nitrogen compound as the sole nitrogen source. The process has been studied in E. coli , and it seems likely that the route of ammonia fixation involves the reductive amination of glutamate by NADP-linked glutamate dehydrogenase and then dispersal of the amino group to other amino acids by transamination.

Hydrolysis of uranium nitrides.

Abstract: Studies were made on the hydrolysis of uranium nitrides (UN and cubic U2N3) by superheated steam. The resulting gaseous products were mainly hydrogen, though with U2N3 the hydrogen generation was replaced by that of nitrogen at higher temperatures. The condensed water contained ammonia, but not hydrazine. Both UN and U2N3 powders were ultimately converted to UO2, after hydrolysis at temperatures up to 600°C; intermediate products (formed below 400°C) were presumably UO2(N) or UN1,7, in the case of UN and UN18 with U2N3. The reaction mechanisms corresponding to the formation of such chemical species were estimated mainly from the behavior of nitrogen and hydrogen evolution and from the yield of ammonia. The effect brought by N2 atmosphere on the ammonia formation and on the dissolution of nitrogen into solids were studied also by the hydrolysis under flowing N2 gas. It was revealed that the yield of ammonia increased and the dissolution was inhibited by N2 atmosphere.

Metabolism of Urea by Chlorella vulgaris

Abstract: Urea metabolism was studied with nitrogen-starved cells of Chlorella vulgaris Beijerinck var. viridis (Chodat), a green alga which apparently lacks urease. Incorporation of radioactivity from urea-14C into the alcohol-soluble fraction was virtually eliminated in cell suspensions flushed with 10% CO2 in air. This same result was obtained when expected acceptors of urea carbon were replenished by adding ornithine and glucose with the urea. Several carbamyl compounds, which might be early products of urea metabolism and a source of the 14CO2, were not appreciably labeled. If cells were treated with cyanide at a concentration which inhibited ammonia uptake completely and urea uptake only slightly, more than half of the urea nitrogen taken up was found in the medium as ammonia. Cells under nitrogen gas in the dark were unable to take up urea or ammonia, but the normal rate of uptake was resumed in light. Since 3-(3,4-dichlorophenyl)-1,1-dimethylurea did not selectively inhibit this uptake, an active respiration supported by light-dependent oxygen evolution in these cells was ruled out. A tentative scheme for urea metabolism is proposed to consist of an initial energy-dependent splitting of urea into carbon dioxide and ammonia. This reaction in Chlorella is thought to differ from a typical urease-catalyzed reaction by the apparent requirement of a high energy compound, possibly adenosine triphosphate.

Evolution of toxic gases from heated plastics

Abstract: A brief investigation has been carried out into the nature and quantity of the toxic gases evolved during the thermal decomposition of polyurethane, urea-formaldehyde, nylon and acrylonitrile in air and in nitrogen. The weight fractions of the polymers evolved as hydrogen cyanide are given, together with the lowest temperatures at which hydrogen cyanide, carbon monoxide, ammonia and nitrogen oxides are evolved. Apparent activation energies for the evolution of hydrogen cyanide and carbon monoxide have been determined. A brief discussion of the experimental data is given.

Preparation of aniline from phenol and ammonia

Abstract: Aromatic amines are made by reacting a phenol with aluminum nitride and either ammonia or a primary or secondary amine at temperatures from 200°-600°C. For example, 2,6-dimethyl-phenol reacts with aluminum nitride and ammonia to yield 2,6-dimethylaniline.

Oxidation of Ammonia on Platinum

Abstract: WE have investigated the mechanism of ammonia oxidation on platinum using a molecular beam to sample in collision-free conditions the species from the surface for mass-spectroscopic analysis. With controlled molecular flow of the reactants to the surface, it was possible to achieve a molecular flux at the surface equivalent to immersion in a gas at pressures up to 10−2 mm Hg, while ensuring that reaction products had a negligible chance of returning to the surface. The technique was outlined in a previous communication1. Preliminary results reported there supported the earlier conclusion of Fogel et al.2 that oxidation proceeded directly to nitric oxide on the catalyst surface.

Environmental Factors Influencing the Sorption of Atmospheric Ammonia by Soils1

Abstract: Under conditions of controlled temperature and atmospheric ammonia concentation, the sorption rate for atmospheric ammonia by six soils from New Jersey decreased only slightly over exposure periods up to 4 days and averaged 55 to 74 kg of NH/sub 3/-n/ha/year. The ammonia sorption rate for these soils increased rapidly with increasing ammonia concentration and moderately with increasing temperature. Calculated energies of activation suggest that sorbed ammonia is held by chemical bonds rather than by physical adsorption. Increasing the velocity of gas flow across the soil surface brings more ammonia into contact with the soil and thus enhances the sorption rate. Soils sorb significant amounts of ammonia from the atmosphere which under some environmental conditions may constitute a major mechanism in the transfer of nitrogen from the atmosphere to soils.

The influence of hydroxamates on ammonia loss from an acid loamy sand treated with urea

Abstract: In a laboratory investigation of the volatilization of ammonia following the application of urea to an acid loamy sand it was found that the loss of ammonia could be delayed for several days and the maximum rate of loss could be reduced by the addition to the soil of various monohydroxamic acids. All the hydroxamic acids used are non-competitive inhibitors of the enzyme urease but in the soil system caprylo-hydroxamic acid and phenylaceto-hydroxamic acid were ineffective in retarding ammonia loss and on a molar basis acetohydroxamic acid (AHA) was a more effective inhibitor than either benzo-, capro- or salicylohydroxamic acid. The effectiveness of AHA in delaying ammonia loss was proportional to its concentration at any one concentration of urea. AHA added to soil several days before the application of urea did not delay losses of volatile ammonia. This may have been due either to chemical inactivation or biological decomposition of AHA or to the proliferation of ureaseforming organisms tolerant towards AHA. When either sulphanilamide, copper sulphate or sodium diethyldithiocarbamate were added to the soil they caused slight delays in ammonia loss but they were far less effective than AHA. The delay caused by AHA treatment was prolonged in the presence of sulphanilamide and this effect was attributed to toxic effects of sulphanilamide on urease-forming organisms.

The Suppression of Stareh Synthesis and the Accumulation of Uridine Diphosphoglucose in Cucumber Leaves due to Ammonium Toxicity

Abstract: This work is a study of the metabolic disorder due to ammonium toxicity in cucumber (Cucumis sativus L. cv. suisei No. 2) leaves. The cucumber was cultured with 20 and 200 mg/l NH3-N for 5 days. In the first half of this experiment, the plant leaves were photosynthesized for 3 hours to study the distribution of 14C in starch and other fractions. The incorporation of photosynthesized 14C into not only starch but also other higher polymers was suppressed by ammonium toxicity. On the other band, the rate of 14C incorporation in 80 % ethanol soluble fraction was higher in the treatment of 200 mg/l NH3-N. In the latter half of experiment, phosphate esters in the loaves were analyzed by column chromatography. The opposing contents of uridine diphosphoglucose (UDPG) and the uridine compound containing sugar or sugar derivative (UDPX) were determined by different ammonia levels. Toxicity of ammonia resulted in an increase of UDPG and a decrease of UDPX. The level of ATP was not changed so much. The content of glucose-6-phosphate (G-6-P) in injured plants was lower than that of normal plants, while ghicose-1-phosphate (G-1-P) and fructose-6–phosphate (F-6-P) were higher in injured plants. These results further suggested the disorder of carbohydrate metabolism due to ammonium toxicity which was reported previously.

Cyanuric acid as nitrogen source for micro-organisms

Abstract: Several fungi, among which species of Penicillium and Hormodendrum (?), were found to utilize cyanuric acid as a nitrogen source, assimilating 66 to 75% of its nitrogen in cell substance. The growth with cyanurate was essentially as good as with ammonia and urea nitrogen. The optimum reaction for growth was around pH 5 to 6, but pH 7 to 8 was suboptimal. No decrease in growth was seen at a cyanurate concentration of 9.3 mM. The triazine ring as such is thus not biologically very stable, and the strong persistance of the triazine herbicides simazine and atrazine must be ascribed to the external substituents and not to the central ring.

Nitrogen Complexes as Models for Nitrogenase with Nitrogen on the Active Site

Abstract: NITROGEN gas reacts in mild conditions in protic media to give the nitrogen complexes [CoH(N2)(PPh3)3]1, and [Ru(NH3)5(N2)]X2 (X = mono anion)2, and related complexes, but the complexed nitrogen molecule has not yet been reduced to ammonia3. Nevertheless, the mechanism of nitrogen uptake in the formation of these complexes may represent the process by which nitrogen is bound in nitrogenase, and the reduction to ammonia could occur in nature by protonation of the complexed nitrogen with simultaneous influx of electrons from the metal. We have therefore studied quantitatively the reactions with strong acids of [CoH(N2)(PPh3)3]1, the substance formulated as [Co(N2)(PPh3)3]4, trans-[IrCl(N2)(PPh3)2]5, and [Ru(NH3)5-(N2)]X2 (X = Cl or BF4)6,7. If protonation occurred, some reduction of the nitrogen with simultaneous oxidation of the metal would be expected. We have found that in general there is oxidation of the metal by the acid, but it leads to nitrogen evolution, often together with hydrogen, and no ammonia.

Flue gas desulfurization with ammonium sulfite

Abstract: Flue gas is desulfurized by absorption in aqueous ammonium sulfite in a multiple-stage countercurrent absorber The absorber effluent solution is regenerated by acidifying a portion thereof with ammonium bisulfate to liberate sulfur dioxide decomposing the resulting ammonium sulfate at high temperature by direct contact with hot combustion gases, and by reacting the ammonia thus formed with a second portion of the absorber effluent solution to prepare fresh ammonium sulfite absorbent solution Regeneration is carried out at constant rate regardless of variations in the flow rates of flue gas and absorbent solution in the absorber; this is accomplished by use of surge tanks for storage of both absorbent and absorber effluent solutions