Influence Of Ammonium Ions Research Articles

The effect of ammonia upon the electrocatalysis of hydrogen oxidation and oxygen reduction on polycrystalline platinum

The influence of ammonium ions on the catalysis of hydrogen oxidation and oxygen reduction is studied by means of rotating ring-disk electrode experiments on polycrystalline platinum in perchloric acid. While ammonium does not affect the hydrogen oxidation reaction, the oxygen reduction reaction is severely poisoned. Poisoning at the cathode explains the majority of the losses observed in polymer electrolyte membrane fuel cells contaminated with ammonia. Voltammetry in deaerated solution suggest that the poisoning can be attributed to either ammonium oxidation or increased binding to OH species.

Refinement of the (NH4)3H(SO4)2 crystal structure: II. X-ray and neutron single-crystal diffraction from phase II at room temperature

The crystal of (NH4)3H(SO4)2 is of special interest due to the possible influence of ammonium ion on the series of phase transitions: I↔II↔ III↔IV↔V↔VII. Earlier, the x-ray single-crystal diffraction study of phase II of the (NH4)3H(SO4)2 crystal showed that the crystal structure of this compound had two crystallographically independent groups of the ammonium ions NH4(1) and NH4(2) but orientational positions of these ammonium ions were not determined exactly. The refinement of the NH4(1) and NH4(2) orientational positions in phase II was carried out by the x-ray and neutron single-crystal diffraction study. The analysis of difference Fourier maps of electron charge density and nuclear density suggested the possibility of disordering of NH4(2) ammonium ions.

The effect of ammonium ions on oxygen reduction and hydrogen peroxide formation on polycrystalline Pt electrodes

The influence of ammonium ions on the activity and selectivity of the electrocatalytic oxygen reduction reaction (ORR) on polycrystalline Pt was investigated in model studies under continuous mass transport, both in sulfuric and perchloric acid solutions. Ammonium was found to increase the yield of hydrogen peroxide, particularly in sulfuric acid, but also in perchloric acid solutions, and also at higher potentials (0.80–0.90 V RHE) typical for fuel cell cathode operation, which may severely impair the long-term stability of membranes and electrodes in fuel cells exposed to fuel gases and/or air containing ammonia. Adsorbed species, assigned to ammonia and nitric oxide, were identified on a Pt film electrode using in situ FTIR spectroscopy. Adsorbed nitric oxide could only be observed in perchloric acid solutions. The higher coverage of adsorbed ammonia in sulfuric acid solution is attributed to a stabilization by coadsorbed (bi-)sulfate species; the higher total coverage in this electrolyte can explain the larger effect of ammonium ions on the ORR activity and selectivity in sulfuric compared to perchloric acid solution.

Glycogenesis from glucose and ureagenesis in isolated perfused rat livers. Influence of ammonium ion, norvaline, and ethoxyzolamide.

The probable involvement of hepatic carbamyl-P in the reciprocal relationship between hepatic ureagenesis and glycogenesis from glucose was explored. Isolated perfused liver preparations from 48-h fasted rats were employed. Moderate (9.2 mM) and relatively high levels of glucose (34 mM) were perfused. Hepatic glycogenesis, glucose-6-P, carbamyl-P, and citrulline levels, hepatic urea formation, and ureagenesis based upon perfusate urea levels were measured. Experimental probes selected to modify hepatic ureagenesis and carbamyl-P production and utilization included: (a) NH4Cl, maintained at 5 mM by continuous infusion (NH4+ is a substrate for carbamyl-P synthase I and glutamate dehydrogenase); (b) norvaline, an inhibitor of ornithine transcarbamylase which catalyzes the first committed step in the urea cycle; and (c) ethoxyzolamide, an inhibitor of carbonic anhydrase which produces HCO3-, an essential substrate for carbamyl-P synthase I. NH4+ increased ureagenesis and decreased glycogenesis. The inclusion of norvaline with NH4+ decreased ureagenesis and increased glycogenesis. Ethoxyzolamide with or without NH4+ inhibited both ureagenesis and glycogenesis, and decreased the hepatic glucose-6-P level. Glycogenesis was greater at 34 mM than 9.2 mM glucose, increased in norvaline-containing preparations correlative with increased availability of carbamyl-P, and decreased when carbamyl-P formation was inhibited by ethoxyzolamide. Kinetic analysis indicated a Km, Glc of 31 mM for glucose phosphorylation preliminary to glycogenesis. Glycogen formation via the "indirect pathway" (i.e. involving extrahepatic glycolysis, transport of lactate to the liver, and glyconeogenesis therefrom) was quantitatively insufficient to account for the observed glycogenesis. Glucokinase is contraindicated by the inverse relationship between hepatic glycogenesis and ATP availability in the ethoxyzolamide-treated preparations. In contrast, carbamyl-P:glucose phosphotransferase activity of the glucose-6-phosphatase system has the characteristics to bridge hepatic ureagenesis and glycogenesis.

Influence of ammonium ion and glucose on mAb production in suspension and fixed bed hybridoma cultures

Previous work indicated that mAb production by a mouse-mouse hybridoma, grown in a fixed bed of macroporous glass beads with a variable feed glutamine concentration, was correlated only to Qv O2 . The work reported in this study further investigated the metabolic parameters modulating mAb production using metabolic data from a continuous stirred tank reactor (CSTR) to interpret the behaviour of cells grown in a fixed bed bioreactor (FBR). For a FBR culture grown with a feed glutamine concentration of 3 mmol l −1, Qv mAb was correlated to Qv O2 and Qv Gln . However, if the feed glutamine concentration was switched between 1 and 3 mmol l −1, the above relationship did not hold, probably because Qv O2 was at or near its maximum value. For both the FBR and CSTR, switches in the feed glutamine concentration suggested that maximum Qv mAb values were associated with glucose concentrations above 12.8 mmol l −1 and an ammonium concentration of 2.0–2.5 mmol l −1.

Influence of ammonium ion on bacterial struvite production

Abstract The influence of ammonium ion on struvite precipitation by 54 bacterial strains isolated from soil and fresh water was investigated. The availability of ammonium made struvite precipitation by some strains possible. However, in others the presence of this ion in itself was not the only factor required for struvite production. Bacterial formation of struvite may involve the adsorption of magnesium and phosphate ions, which, together with the release of ammonium ions, may form a microenvironment in the vicinity of the cell in which ions may accumulate in amounts sufficient to trigger crystal formation.

The influence of ammonium ions on the aggregation of chicken liver xanthine dehydrogenase

Conference Article| October 01 1987 The influence of ammonium ions on the aggregation of chicken liver xanthine dehydrogenase ANTONIO LOPEZ CABRERA; ANTONIO LOPEZ CABRERA 1Department of Biochemistry and Phisiology, University of Barcelona, Marti Franquès, 1, 08028 Barcelona, Catalunya, Spain Search for other works by this author on: This Site PubMed Google Scholar PAU BRUGUERA; PAU BRUGUERA 1Department of Biochemistry and Phisiology, University of Barcelona, Marti Franquès, 1, 08028 Barcelona, Catalunya, Spain Search for other works by this author on: This Site PubMed Google Scholar ENRIC I. CANELA ENRIC I. CANELA 1Department of Biochemistry and Phisiology, University of Barcelona, Marti Franquès, 1, 08028 Barcelona, Catalunya, Spain Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1987) 15 (5): 883–884. https://doi.org/10.1042/bst0150883 Article history Received: March 24 1987 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation ANTONIO LOPEZ CABRERA, PAU BRUGUERA, ENRIC I. CANELA; The influence of ammonium ions on the aggregation of chicken liver xanthine dehydrogenase. Biochem Soc Trans 1 October 1987; 15 (5): 883–884. doi: https://doi.org/10.1042/bst0150883 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search Keywords: PAGE, polyacrylamide gel electrophoresis This content is only available as a PDF. © 1987 Biochemical Society1987 Article PDF first page preview Close Modal You do not currently have access to this content.

Influence of ammonium ions on calcite and struvite formation byazotobacter in chemically defined media

The formation of calcite and struvite crystals byAzotobacter vinelandii andA.chroococcum was studied on chemically defined media. The crystals were identified microscopically and by X-ray differentiation analysis. Calcite crystal formation was inhibited specifically with 0.05 % ammonium sulfate. However, 0.2 % ammonium sulfate was required for struvite crystal formation.

Influence of ammonium ions on the electronic structure of the hexafluorogermanate ion

Influence of ammonium ions on the electronic structure of the hexafluorogermanate ion

The influence of ammonium ion on local hepatic Po2 and portal blood flow in normal and cirrhotic rats

The influence of ammonium ion on local hepatic Po2 and portal blood flow in normal and cirrhotic rats

Comparison of Metabolic Effect of Ammonia and Adrenaline Infusions in Sheep

Intravenous infusions of ammonium chloride (62.3 mumol.kg-1.min-1) for 30 min caused a significant increase in blood glucose, lactate, pyruvate and free fatty acid (FFA) levels. A similar effect was also observed during infusion of adrenaline. Propanolol--a beta-receptor blocking agent--completely prevented the rise of blood pyruvate and lactate after adrenaline when 8.3 microgram.kg-1.min-1 of propranolol were infused, but not after NH4Cl administration. Lipolytic actions of adrenaline were completely prevented but that of NH4Cl was only significantly diminished by blockade of beta-receptors with propranolol. It was concluded that the influence of ammonium ions on blood lactate and pyruvate and FFA was not entirely mediated by adrenaline.

Influence of ammonium ions on mechanical and electrophysiological responses of skeletal muscle.

Substitution of ammonium ions for sodium ion initially potentiated and then depressed twitch tension of the frog sartorius muscle. The extent of potentiation and the rate of depression of the twitch were dependent upon the concentration of ammonium ions. Ammonium ion depolarized individual muscle fibers in proportion to concentration. Maximum depolarization (33 mV) occurred in muscles equilibrated in 120 mM ammonium-Ringer for 30 min. At the higher concentration of ammonium (72--120 mM), the potentiation was quickly reversed and the tension response was eliminated completely. The gradual loss of twitch tension was accompanied by progressive decrease in the electrical excitability of individual muscle fibers. Raising the extracellular calcium concentration fivefold reduced the twitch-depressant effect of ammonium ions by maintaining excitability of the muscle fibers. Caffeine contractures (3 and 10 mM) in muscles preequilibrated in 72 mM ammonium-Ringer developed similar tensions to paired controls muscles, but the onset of tension was more rapid in the ammonium-treated muscle. It was concluded that the depression of tension could be accounted for by the loss of membrane excitability and that the evidence did not support the hypothesis that ammonium ions acted at other sites in the excitation contraction coupling.

Polarographic and Spectroscopic Studies on the Ion-pair Formation of Trioxalatocobaltate(III) Ions with Cations in Aqueous Solutions

Abstract The ion association between trioxalatocobaltate(III) anion and uni-, bi- and tervalent cations in aqueous solutions has been studied by polarographic and ultraviolet, visible and infrared spectroscopic methods. The association constants have been obtained by the measurement of the polarographic diffusion current of trioxalatocobaltate(III) ions in the presence of varied concentrations of cations at ionic strength 0.1 (NH4NO3) and 25°C. The influence of ammonium ion was taken into consideration in the treatment of polarographic data. The values obtained are 7.9 for (CH3)4N+[Co(ox)3]3−, 3.7±0.4 for (C2H5)4N+[Co(ox)3]3−, 22±1 for Na+[Co(ox)3]3−, 56±6 for Mg2+[Co-(ox)3]3−, 55±4 for Ca2+[Co(ox)3]3−, 53±3 for Sr2+[Co(ox)3]3−, 55±7 for Ba2+[Co(ox)3]3− and 118±17 for Al3+[Co(ox)3]3−. The association constant of NH4+[Co(ox)3]3− was determined by the conductivity measurement to be 33.6 (logK=1.53) at zero ionic strength. No change was observed in the visible, the ultraviolet and the infrared absorption spectra of trioxalatocobaltate (III) ions upon the addition of various cations even at the concentration at which the ion-pair formation is assumed to occur from the polarographic studies. These facts indicate that, in a sense of equilibrium study, there is no direct interaction between the complex anion and the cation, but one or more water molecules interpose between the two ions.

The influence of ammonium ions on glycolysis in red cells

The effect of different ions on red cell metabolism has been examined. Ammonium ions have been found to have a specific effect on the hexose monophosphate shunt. This effect has been observed by adding ammonium chloride and ammonium hydroxide to the cells. The stimulative effect of ammonium on the pentose phosphate pathway is an independent phenomenon, not related to increased alkalinity of the medium. Increasing alkalinity, by addition of sodium hydroxide and potassium hydroxide stimulates mainly the anaerobic pathway of glycolysis. The observed effects were found to be not due to changes in ionic strength or in osmolarity of the media.