Role Of Ammonium Ions Research Articles

A theoretical study on the role of ammonium ions in the double-layered V2O5 electrode.

Double-layered V2O5 and its analogues have received increasing attention as a proper cathode for Mg2+, Na+, Li+ ion batteries, even for ammonium ion batteries. Our theoretical research focuses on the effects of NH4+ ions on the structural stability and the ion diffusion properties of double-layered V2O5. The elastic constant calculations indicate the NH4+ and water contents have a dramatic influence on the stability of the electrode. When the ratio of H2O and ammonia ions decreases to (NH4)0.125V2O5·0.125H2O, double-layered bronze will transform into other phases. The predicted specific capacity for the redox process from (NH4)0.5V2O5·0.5H2O to (NH4)0.125V2O5·0.125H2O is 54.6 mA h g-1, which agrees with the experimental value of 55.6 mA h g-1. From the diffusion barrier calculations, it is found that the H2O molecules can shield the polarization of NH4+ and lower the diffusion barrier of NH4+ ions. Furthermore, the migrations of common charge carriers in NH4+ pre-intercalated V2O5 have also been studied, which implies that Li+, Zn2+, Na+, Mg2+ ions may move easily in the electrode with energy barriers lower than 525 meV. Our findings match well with the reported experimental results. A special structure of Mg6NH4V8O20 with a much higher Mg ion concentration has been reported. Our findings show that the theoretical specific density of Mg batteries based on NH4+ pre-intercalated V2O5 can be improved to 431 mA h g-1, which is 2.5 times larger than the reported values. This work highlights the effects of the ratio of NH4+ and H2O on double-layered V2O5 and provides insights into designing vanadium oxide based fast-diffusion multivalent ion conductors, which are suitable for battery applications.

Role of Ammonium Ions in Colloidal Silica Slurries for Ru CMP

The chemical mechanical polishing (CMP) of ruthenium (Ru) based barrier layer has been a pivotal process in the manufacture of a novel copper (Cu) interconnect structure. This paper mainly investigated the role of NH4+ in colloidal silica slurries for Ru CMP. The polishing results show that the Ru removal rate increases with the increasing concentration of NH4+. The influence mechanism of NH4+ on removal rate of Ru was investigated by electrochemistry, scanning electron microscope (SEM) and zeta potential. It is revealed that the NH4+ can promote the surface corrosion rate of Ru by forming a water-soluble Ru-NH4 complex with Ru oxide, meanwhile can also result in the neutralization of the zeta potentials of both silica particles and the Ru surface, and thus can lead to the decrease of the electrostatic repulsive force and the increase of the mechanical abrasion intensity between silica particles and Ru surface. Further, the surface quality of the polished Ru wafer and slurry stability were evaluated, and the results show that the addition of an appropriate amount of NH4+ can achieve a low surface roughness of Ru and a high slurry stability.

Role of ammonium ions on the stability of TiO2 sol

In this paper, the role of the trace ammonium ions on the stability of TiO2 sol prepared by peroxo titanic acid (PTA) sol was investigated. The results showed that the removal of ammonium ions in PTA sol is beneficial to reduce agglomeration and increase the negative charge on the surface of TiO2 colloidal particles, contributing to the higher stability and longer storage time of the TiO2 sol. It was also approved by the increase of interaction energy calculated by classical DLVO theory. In addition, the photocatalytic performance of TiO2 sol was improved due to the decrease of aggregation of TiO2 colloidal particles.

Role of ammonium ion on the aggregation and adsorption properties of sodium dodecylsulfate

ABSTRACTThe role of mixed counterion toward the aggregation behavior of sodium dodecylsulfate (SDS) is quantified by determining the critical micelle concentration (cmc) of SDS micelle in the presence of added NH4Cl salt. The dependence of cmc of SDS on added salt is explained in the light of the modified Corrin–Harkins equation and the nonlinearity of this plot is shown due to the exchange of Na+ ion by added ion. The aggregation number (N) of SDS micelle is also calculated using the steady-state fluorescence method, where sudden change in N value was observed in two different concentration regions of the modified CH plot. Furthermore, the hydrodynamic diameter (dH) of dodecyl sulfate micelles was determined using the dynamic light scattering method. In scattering studies, a sharp change in the value of dH occurred at around 50 mM of added salt, which might hint toward the shape change of dodecyl sulfate micelle. The surface excess values of SDS in the presence of mixed inorganic counterion are also calculated in the light of the Gibbs adsorption isotherm.

Structures of N-acetyl-DL-isoleucine, N-acetyl-DL-alloisoleucine and their ammonium salts; role of ammonium ions in crystal structure formation.

The crystal structures of N-acetyl-DL-isoleucine, N-acetyl-DL-alloisoleucine and their ammonium salts show that these four compounds exist as racemic compounds around room temperature. The two ammonium salts are arranged around a 21 screw axis, forming a helical column which consists of ammonium ions and single enantiomeric anions similar to the crystals of the ammonium salts of optically active N-acetyl-L-isoleucine and N-acetyl-D-alloisoleucine. The ammonium ion and the carboxylate ion in the helix are connected by three hydrogen bonds, the fourth hydrogen bond being formed between the ammonium ion and an external acetyl amino group of the neighboring helical column. The fourth hydrogen bond is formed between the ammonium ion and an external acetyl amino group of the neighboring 21 column. Ammonium N-acetyl-DL-alloisoleucinate was revealed to exist as an unstable racemic compound due to conformational similarity between the racemic and optically active compounds in the solid state and was optically resolved by fractional crystallization at 293 K.

Role of Ammonium Ions in the Formation of Ammonium Uranyl Peroxides and Uranyl Peroxo-oxalates

The flexibility of the ammonium ion environment is suitable for inducing the formation of several uranyl peroxides and peroxo-oxalates. For a given concentration of uranium and various oxalate/uranium ratios, by varying the pH with ammonium hydroxide, crystals of eight compounds have been isolated and characterized by X-ray diffraction, in addition to the studtite (UO2)(O2)·4H2O. All the compounds contain anionic uranyl polyhedra clusters with charge compensated by ammonium ions. Three are uranyl peroxides built from uranyl hexagonal bipyramids [(UO2)(O2)3]4– or [(UO2)(O2)2(OH)2]4– sharing peroxide or dihydroxyl equatorial edges to form cage clusters [(UO2)28(O2)42]28– (U28) and [(UO2)44(O2)66]44– (U44) in 7 and 3 respectively, or crown-shaped cluster [(UO2)32(O2(OH)2)52]40– (U32R) in 2. In these uranyl peroxides the pentagonal and hexagonal uranyl polyhedra rings are stabilized by ammonium ions. The other five compounds are uranyl peroxo-oxalates with various condensations of uranyl hexagonal bipyramids: (i) condensation of two [(UO2)(O2)(C2O4)2] bipyramids by peroxide ion sharing to form the dimer [(UO2)2(O2)(C2O4)4]6– (U2Ox4) in 8, (ii) assembly of five [(UO2)(O2)2(C2O4)] bipyramids linked by sharing peroxide to form the [(UO2)5(O2)5(C2O4)5]10– (U5Ox5) pentameric rings in 4 and 6, (iii) further condensation of 12 U5Ox5 rings through bis-bidentate oxalates to create the [(UO2)60(O2)60(C2O4)30]60– (U60Ox30) nanosphere in 5, (iv) replacing an oxalate by two hydroxide ions in U5Ox5 rings and sharing of the OH–OH bridge between two pentamers to form the dimer of pentamers [(UO2)10(O2)10(OH)2(C2O4)8]18– (U10Ox8) in 9. In the last four compounds, the ammonium ions stabilize the pentameric cycles. The ammonium ion has different effects, particularly in the case of pentamers, and thus provides access to a large panel of cluster sizes.

Ammonia Sensing Mechanism of Tungstated-Zirconia Thick Film Sensor

A sensor element of interdigital capacitor (IDC) electrodes covering with tungstated-zirconia thick film shows a good response and cross-sensitivity in gaseous ammonia sensing. The sensing mechanism of the tungstated-zirconia thick film has been investigated by means of in situ FT/IR and H/D isotope effect. In the absence of ammonia, the role of protonic conduction was clarified by the H/D isotope effect of water vapor on the conductivity. In the presence of gas phase ammonia, the conductivity of the tungstated-zirconia thick film significantly increased. The conductivity in the presence of ammonia showed unique temperature dependence, i.e., the conductivity at first increased with a decrease in temperature, showed the maximum at 633 K, and then decreased with further decrease in temperature. In situ FT/IR spectra revealed the presence of both ammonium ion adsorbed on Brønsted acid site and ammonia coordinated to Lewis acid site on the tungstated-zirconia surface. Temperature dependence and dynamic response of the conductivity were in good accordance with the surface concentration of ammonium ion adsorbed on Brønsted acid site. The contribution of ammonium ion to electric conductivity was indicated. The role of ammonium ion as a migrating species for ammonia sensing was verified from negligible H/D isotope effect of ammonia and mobility of ammonium ion.

Synthesis of hafnium germanate (HfGeO 4) by co-precipitation routes

Hafnium germanate (HfGeO 4) presents under X-ray excitation a high UV fluorescence at around 365 nm that may be used for X-ray imaging. Its synthesis by different co-precipitation routes with sodium hydroxide, ammonia, potassium hydroxide, dimethylamin and tetramethylammonium hydroxide was studied. Precipitated amorphous hydroxides were then washed, dried and calcined at 1100°C for 6 h to make HfGeO 4 crystallize. Hydroxides and oxides were characterized by Fourier transformed infrared spectroscopy, X-ray diffraction and X-ray fluorescence. Hence we could emphasize importance and role of ammonium ions on the structure and optical properties of the synthesized products. More particularly, it has been demonstrated that only amorphous products precipitated in the presence of ammonium ions lead to single-phase HfGeO 4.

Fate and Role of Ammonium Ions during Fermentation of Citric Acid by Aspergillus niger

Stoichiometric modeling of the early stages of the citric acid fermentation process by Aspergillus niger revealed that ammonium ions combine with a carbon-containing metabolite inside the cell, in a ratio 1:1, to form a nitrogen compound which is then excreted by the mycelium. High-performance liquid chromatography analysis identified glucosamine as the product of the relationship between glucose and ammonium during the early stages of the citric acid fermentation process. Slightly acidic internal pHs, extremely low ammonium ion concentrations inside the cell, and glucosamine synthesis come into direct contradiction with the earlier theory of the ammonium pool inside the cell, regarded as responsible for inhibition of the enzyme phosphofructokinase. At later fermentation stages, when the mycelium is involved in a process of fragmentation and regrowth, the addition of ammonium sulfate leads to a series of events: the formation and secretion of glucosamine in elevated amounts, the short inhibition of citrate synthesis, growth enhancement, the utilization of glucosamine, and finally, the enhancement of citric acid production rates. Obviously, the enzymatic processes underlining the phenomena need to be reexamined. As a by-product of the citric acid fermentation, glucosamine is reported for the first time here. Suitable process manipulations of the system described in this work could lead to successful glucosamine recovery at the point of its highest yield before degradation by the fungus occurs.

Influence of NH4-Rb substitution on the phase transitions with different kinds of proton disorder in mixed [(NH4)1–x Rb x ]3H(SO4)2 crystals

The role of ammonium ions in order–disorder ferroelastic, ferroelectric and structural phase transitions was studied in mixed [(NH4)1–x Rb x ]3H(SO4)2 0 < x < 1 crystals by dielectric spectroscopy and ac calorimetry. A new superprotonic phase was detected in compounds with x > 0·6. It was found that small Rb concentrations, x < 0·05, strongly smear out the temperature anomalies of dielectric constant and specific heat for phase transitions II–III, III–IV, IV–V and V–VIII. At x > 0·09 these phase transitions are fully suppressed. Finally, for Rb concentrations 0·05 < x < 0·9 a proton glass phase appears below 35 K.

The role of ammonium ions during toluene ammoxidation on α-(NH 4) 2[(VO) 3(P 2O 7) 2] used as catalyst

Isotopic transient experiments in vacuum of the ammoxidation of toluene were carried out, applying the temporal-analysis-of-products reactor (TAP) using α-( 14NH 4) 2[(VO) 3(P 2O 7) 2] as catalyst and 15NH 3-containing ammoxidation feed gas. The study revealed the participation of ammonium ions in the N-insertion step during benzonitrile formation. The benzonitrile formed during the ammoxidation pulses is composed of the 14N- and 15N-product. The share of the 15N-benzonitrile increased with pulse number.

AMP deaminase reaction as a control system of glycolysis in yeast. Role of ammonium ion in the interaction of phosphofructokinase and pyruvate kinase activity with the adenylate energy charge.

The role of ammonium ion and AMP deaminase (EC 3.5.4.6) reaction in the activation of phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40) by the decrease in the adenylate energy charge was investigated using permeabilized yeast cells. Response of AMP deaminase, phosphofructokinase, and pyruvate kinase to variation in the energy charge is typical of the ATP-regenerating enzymes: an activation with the decrease in the energy charge under the in situ conditions. The addition of polyamine activated AMP deaminase in situ, resulting in the subsequent increase in ammonium production, which can stimulate the phosphofructokinase activity with the increase in the optimal energy charge value giving maximal activity of the enzyme. The optimal energy charge value of phosphofructokinase was 0.2-0.25 in the absence of ammonium ion and was shifted to the value above 0.5 by the addition of ammonium ion, whereas Pi, an activator of the enzyme showed little effect on the increase in the optimal energy charge value. The optimal energy charge value of AMP deaminase and pyruvate kinase was not affected by the addition of their effectors. Modulation of the response to the energy charge of phosphofructokinase and pyruvate kinase was analyzed in terms of the "activation coefficient," which was defined as the ratio of the activity at the energy charge of 0.6 to that at the value of 0.9. Activation of phosphofructokinase by the physiological decrease in the energy charge (0.9 to 0.6) can be enhanced by the increase in ammonium ion specifically, although the coefficient of pyruvate kinase remained unaffected by ammonium ion. These results suggest that the AMP deaminase reaction as an ammonium-forming reaction can participate in a key role in the stimulation of phosphofructokinase or glycolytic flux in cells.

Morphogenesis in callus tissue ofMedicago sativa: The role of ammonium ion in somatic embryogenesis

Exogenously supplied ammonium ion is critical to alfalfa morphogenesis in vitro. In alfalfa, the ability to induce the formation of either roots or somatic embryos provided an opportunity to examine the effects of ammonium ion on each pattern of morphogenesis. Somatic embryo formation required a minimum of 12.5 mM NH4+ in regeneration medium for optimal expression. Root formation was inhibited by NH4+ levels of 50 mM and above, and occurred in the absence of exogenous NH4+. At high levels of NH4+ somatic embryos were formed from cells exposed to the root-inducing combination of hormones. This observation suggests that the growth regulators and exogenously supplied ammonium ion comprise an interactive system controlling the in vitro pattern of alfalfa morphogenesis.

Studies on the activity of rumen protozoa. I. Role of ammonium ions and free amino acids in the regulation of nitrogen metabolism in rumen protozoa.

SummaryThe protozoal masses isolated from the rumen liquor (rl) of a crossbred Red‐Dane Sahiwal calf and two buffalo calves were made up of large and very large and small and medium sized cells, respectively.From kinetic and electrophoretic studies it was evident that more than one type of protease is present in these protozoa. The partially purified proteases are relatively less sensitive to variations in temperature and pH and were completely inhibited by 2.5, 5.0, 10.0 mM NH4C1 and activated by 2 mM CaCl2. The presence of free amino acids (425, 850 μg) in the incubation medium decreased the uptake of U‐14C‐L‐leucine and serine and their incorporation into protozoal proteins. NH4+ ions greatly enhanced the uptake and incorporation of 14C‐amino acids into proteins in larger sized protozoa. It was concluded that the levels of NH4+ ions regulate the uptake of amino acids, their incorporation into proteins and proteolysis in large sized rumen protozoa.ZusammenfassungAktivität der PansenprotozoenI. Die Bedeutung der Ammoniumionen und freien Aminosäuren bei der Regulation des Stickstoffmetabolismus der PansenprotozoenDie aus der Pansenflüssigkeit eines Kalbes (Kreuzung Red‐Dane/Sahiwal) sowie von zwei Büffelkälbern isolierte Protozoenpopulation setzte sich aus verschieden großen Zellen zusammen, welche folgendermaßen klassifiziert wurden: sehr große, große, mittelgroße und kleine.Kinetische und elektrophoretische Untersuchungen zeigten, daß Protozoen mehr als einen Proteasentyp besitzen. Die partiell gereinigten Proteasen sind relativ wenig empfindlich für Temperatur‐ und pH‐Änderungen. Durch 2,5; 5,0; 10,0 mM NH4Cl wurden die Proteasen vollständig inaktiviert durch 2 mM CaCl2 hingegen aktiviert. Freie Aminosäuren (425, 850 μg) im Inkubationsmedium (O,5 ml) reduzierten die Aufnahme von U‐14C‐L‐Leucin und Serin sowie deren Einbau in die Protozoenproteine. NH4+‐Ionen erhöhten die Aufnahme sowie den Einbau von 14C‐Aminosäuren in die Proteine der großen Protozoen.Folgerung: NH4+‐Ionen regulieren die Aufnahme von Aminosäuren und deren Einbau in die Proteine sowie die Proteolyse bei den großen Protozoen.RésuméActivité des protozoaires de la panseI. Signification de ions ammonium et des acides aminés libres lors de la régulation du métabolisme de l'azote des protozoaires de la panseLes populations de protozoaires isolées à partir du liquide de la panse d'un veau (croisement Red‐Dane/Sahiwal) et de deux veaux de buffle se sont réparties en cellules de différentes grosseurs, classées de la manière suivante; très grosses, grosses, moyennement grosses et petites.Des recherches cinétiques et électrophorétiques ont montré que les protozoaires possèdent plus d'un type de protéases. Les protéases partiellement purifiées sont relativement moins sensibles aux changements de température et de pH. Les protéases ont été complètement inactivées par 2,5, 5,0 et 10,0 mM NH4Cl et activées par contre par 2 mM CaCl2. Des acides aminés libres (425, 850 μg) dans un milieu d'incubation (0,5 ml) ont réduit la prise de U‐14C‐L‐leucine et sérine ainsi que leur incorporation dans les protéines des protozoaires. Les ions NH4+ ont augmenté la prise et l'incorporation de 14C‐acides aminés dans les protéines des gros protozoaires.Conclusions: les ions NH4+ régularisent la prise des acides aminés et leur incorporation dans les protéines ainsi que la protéolyse chez les gros protozoaires.ResumenActividad de los protozoos del rumen 1. Significación de los iones amonio y aminoácidos libres en la regulación del metabolismo del nitrógeno de los protozoos del rumenLas masas protozoarias aisladas del líquido de la panza de una ternera (cruce roja danesa/Sahiwal) así como de dos terneros de búfala estaban compuestas por células de tamaños diferentes, las cuales se clasificaron de la manera siguiente: muy grandes, grandes, medianas y pequeñas.Los estudios cinéticos y electroforéticos pusieron en evidencia que estos protozoos poseen más de un tipo de proteasas. Las proteasas purificadas de forma parcial son menos sensibles relativamente a los cambios térmicos y del pH. Mediante 2,5; 5,0; 10,0 mM NH4Cl se inhibieron las proteasas por completo, mientras que las mismas fueron activadas por 2 mM CaCl2. La presencia de aminoácidos libres (425, 850 μg) en el medio de incubación (0,5 ml) reducían la asimilación de leucina U‐14C‐L y serina y su incorporación en las proteínas protozoales. Iones NH4+ aumentaban la asimilación e incorporación de aminoácidos 14C en las proteínas de los protozoos grandes. Se saca en conclusión que los niveles de los NH4+ regulan la asimilación de los aminoácidos, su incorporación en las proteínas y la proteolisis en los protozoos ruminales de tamaño grande.

Effect of exercise on AMP deaminase and adenylosuccinase in rat skeletal muscle.

Effect of exercise on AMP deaminase and adenylosuccinase in rat skeletal muscle.

Role of ammonium ion in the biosynthesis of beta-nitropropionic acid.

The metabolism of inorganic nitrogen compounds was studied in extracts of Penicillium atrovenetum which had been grown under conditions in which beta-nitropropionic acid (BNP) synthesis varied from 0 to 12.5 mumoles per ml. None of the extracts was able to oxidize ammonium ion or nitrite. An enzyme was detected which catalyzed the oxidation of hydroxylamine with cytochrome c as the electron acceptor. The activity of this enzyme was not related to the ability of the organism to produce BNP. Nitrate and nitrite reductase activities were detected only in P. atrovenetum cultures grown on nitrate as a nitrogen source. These results indicated that BNP synthesis is probably not directly associated with the metabolism of inorganic nitrogen compounds and that an organic pathway for the formation of the nitro group is more likely. The activities of certain enzymes related to the metabolism of aspartic acid were investigated. Aspartate ammonia-lyase activity could not be detected in P. atrovenetum extracts. Aspartate aminotransferase and glutamate dehydrogenase activities were found in the extracts but were highest in the cultures which did not produce BNP. beta-Nitroacrylic acid reductase activity was highest in extracts of cultures which were actively synthesizing BNP.