Ammonia In Medium Research Articles

Kinetics of Dissolution of Tenorite in Ammonium Media

In this work, the dissolution kinetics of tenorite (CuO) in a NH4OH-H2O system was studied. The studied temperature range was 5–55°C, ammonium hydroxide concentration between 0.1 and 0.75 M, and a particle size range of 5–24 µm. The stirring speed, pH of the ammonia solution, and various agents were also studied. The results indicated that the leaching of tenorite occurred quickly with a particle size of 5 µm in a 0.45 M solution of NH4OH for a pH value equal to 10.5. Dissolution of CuO also increases as temperature and the concentration of NH4OH increase. For concentrations less than 0.10 M, there is almost no leaching tenorite. By decreasing the particle size, the dissolution of CuO increase. Results show the stirring speed had no significant effect on the leaching rate of tenorite for values above 250 rpm. Leaching kinetics was analyzed using the model of the surface chemical reaction. The reaction rate was of the order of 2.2 with respect to the concentration of ammonium hydroxide and inversely proportional to the initial particle size. Activation energy of 59 kJ/mol was estimated for the temperature range of 5–55°C.

Influence of light and mineral nitrogen forms on the activity of some enzymes in Cucumis sativus L. cotyledons

It was demonstrated that when nitrogen was deficient in the medium, the activity of glutamine synthetase (GS), glutamate dehydrogenase (GDH), alanine aminotransferase (GPT) and aspartate aminotransferase (GOT) in etiolated cucumber cotyledons was higher than in those of seedlings growing under light. When the plants grew on nitrate or ammonium medium, light stimulated GS activity and depressed that of GDH and GOT, without changing the activity of GPT. It was found that the influence of the form of mineral nitrogen on the activity of the studied enzymes was dependent on light. On the basis of the results. obtained, the contribution of the GS glutamate synthase system and GDH to the incorporation of the taken up nitrogen into the amino acids in light and in darkness is discussed.

Effect of glutamine substitution by TCA cycle intermediates on the production and sialylation of Fc-fusion protein in Chinese hamster ovary cell culture

In an effort to reduce the accumulation of ammonia in culture medium, three different TCA cycle intermediates, (alpha-ketoglutarate (α-KG), citric acid and succinic acid) along with glutamic acid for a comparison, were examined as a substitute for glutamine with rCHO cell line producing a Fc-fusion glycoprotein. Among them, α-KG showed the best production performance. When cells were cultivated with 4mM α-KG, the final ammonia concentration did not exceed 3mM, which is less than one fourth of that with 4mM glutamine. The replacement of glutamine increased the lag phase and reduced cell growth. However, it increased the specific productivity by 2.7-fold, resulting in a 1.3-fold increase in the maximum product concentration. Furthermore, the sialic acid content of the Fc-fusion protein with 4mM α-KG was higher than that with 4mM glutamine in all cultures, most likely due to the lower ammonia concentration. The results of Western blotting and activity assays of intracellular α-2,3-sialyltransferase and extracellular sialidases are in good agreement with tests done to assess the sialic acid content of the Fc-fusion protein. Taken together, the data obtained here demonstrate that α-KG is a potential substitute for glutamine for improved glycoprotein production in rCHO cells.

Catalytic oxidation of benzylamine over N-stimulated graphite oxide

In this paper, we synthesized nitrogen-doped graphite oxide materials by the chemical vapor deposition method, and employed the cheap metal-free catalytic material to replace the noble metal catalysts that are currently used for the production of amide compounds. The metal-free catalytic reactions were performed in the liquid systems to synthesize benzamide by the oxidation of benzylamine. It is found that high selectivity and superior yield towards benzamide was achieved in the ammonia medium. In contrast, oxygen was activated in water to transform benzylamine to the imine compound. A variety of reaction parameters were investigated to study the reaction mechanisms as well as the role of ammonia. We conclude that the reaction process involves multiple elementary steps with the imine as the intermediate. Our work enriches the carbocatalysis knowledge and sheds lights on the C-H bond activation.

The influence of potassium and calcium ions on nitrogen metabolism of cucumber seedlings

It was found that K<sup>+</sup> or Ca<sup>2+</sup> deficiency in a nitrate or ammonium medium increased the amount of accumulated total and non-protein nitrogen in some organs of cucumber seedlings, as also caused changes in accumulated potassium and calcium. Lack of K<sup>+</sup> or Ca<sup>2+</sup> in a medium which did not contain nitrogen led to an increased level of glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in the cotyledons and roots of cucumbers. Similar changes in the activity of these enzymes were noted in certain organs of seedlings growing in nitrate or ammonium medium with decreased K<sup>+</sup> or Ca<sup>2+</sup> contents, although the magnitude of these changes depended upon the applied dosage of these cations, the form of mineral nitrogen, developmental phase of plants and the plant organ dealt with.

The effect of ammonium ions on the activity of glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase in Cucumis sativus L. seedlings

Changes in the activity of glutamate dehydrogenase (GDH), alanine aminotransferase (GPT) and aspartate aminotransferase (GOT) were studied in various organs of <em>Cucumis sativus</em> L. seedlings in relation to the uptake of mineral nitrogen (in form of N0<sub>3</sub><sup>-</sup> or NH<sub>4</sub><sup>+</sup> ) from the medium. Activity of GDH, GPT, and GOT was higher in young leaves and roots of cucumber seedlings if the plants developed- in an ammonium medium. No similar changes of aminotransferases activity were noted in the cotyledons. Factors affecting varying effect of ammonium ions upon GPT and GOT activity are discussed for particular organs of cucumber seedlings.

Aspartate aminotransferase isoenzymes in cucumber roots as depending upon the mineral composition of the medium

Aspartate aminotransferase (GOT) isoenzymes separated by means of electrophoresis on cellulose acetate gel were examined. Five GOT isoenzymes were discovered in cucumber roots after several days of their growth. The activity of these isoenzymes was dependent upon the mineral composition of the medium. If the medium did not contain nitrogen, isoenzymes 1, 3, and 4 showed only slight activity. Activity of all of the isoenzymes in the roots of seedlings assimilating NH<sub>4</sub><sup>+</sup> ions was higher than in the roots of seedlings assimilating N0<sub>3</sub><sup>-</sup> ions. Higher activity was observed in all of the isoemzymes in the nitrate or ammonium medium lacking calcium, while only some showed higher activity at the lack of potassium.

Inhibition of nitrate reductase by azide in microalgae results in triglycerides accumulation

Sodium azide (Az) induces accumulation of triglycerides (TAG) in the green alga Chlorella desiccata with minimal growth retardation (Rachutin-Zalogin & Pick, joint manuscript). To clarify the mechanism of this effect, the involvement of respiration, production of reactive oxygen species (ROS) and suppression of nitrate reductase (NR) was investigated. Different respiratory inhibitors induced minor or no TAG accumulation, ruling out respiration as the primary Az target. ROS generators failed to induce massive TAG accumulation, but the singlet oxygen quencher DABCO inhibited Az-induced TAG biosynthesis and this inhibition was suppressed in 30% D2O. Az-induced TAG accumulation was observed in nitrate, but not in ammonium medium, in which growth is not dependent on NR. Effects of cyanide, cyanate, a singlet oxygen quencher, D2O and of CO2 limitation on TAG accumulation are consistent with inhibition of NR. C. desiccata NR activity is Az-sensitive. The results suggest that Az-induced TAG accumulation results primarily from photoinactivation of NR.

Preparation of Excitation‐Independent Photoluminescent Graphene Quantum Dots with Visible‐Light Excitation/Emission for Cell Imaging

We report the first pyrrole-ring surface-functionalized graphene quantum dots (p-GQDs) prepared by a two-step hydrothermal approach under microwave irradiation in an ammonia medium. The most distinct feature of the functionalized GQDs is that both the excitation and emission wavelengths fall into the visible-light region. The p-GQDs are excited by visible light at λ(ex) 490 nm (2.53 eV) to emit excitation-independent photoluminescence at a maximum wavelength of λ(em) 550 nm. This is thus far the longest emission wavelength reported for GQDs. Stable photoluminescence is achieved at pH 4-10 with an ionic strength of 1.2 mol L(-1) KCl. These features make the p-GQDs excellent probes for bio-imaging and bio-labeling, which is demonstrated by imaging live HeLa cells.

Thermal diffusion of 67Ga from irradiated Zn targets

Gallium-67 is a cyclotron produced radionuclide and 67Ga-citrate complex scans are performed in a variety of applications in Nuclear Medicine. The aim of this study was to evaluate a new method for the chemical separation of 67Ga from Zn targets. The method has 2 steps, first the thermal diffusion of 67Ga with concentrated acetic acid and then purification by cation exchange in ammonium medium. The final 67Ga solution was obtained in 0.1molL−1 HCl with the desirable high purity.

Abstract 104: Effects of Pinacidil and Ca 2 + on Sodium-loaded Rat Heart Mitochondria

Deterioration of the contractile parameters of the heart muscle caused by ischemia and followed reperfusion is known as the main postoperative complication which is related to Ca 2+ and Na + overload in cardiomyocytes and mitochondria. Pinacidil reduced the overload in ischemia/reperfusion experiments. The mechanism of this phenomenon is still not clear. We hypothesized that increased ion permeability of the inner mitochondrial membrane (IMM) followed drop of electrochemical potential (ΔΨ mito ) can reduce the calcium. The aim of the study was to elucidate the effect of pinacidil (100 μM) and Ca 2+ (100 μM ) on swelling, oxygen consumption and ΔΨ mito of isolated sodium-loaded rat heart mitochondria (RHM(Na)) energized glutamate and malate. Pinacidil significantly enchanced the permeability of IMM to protons in ammonium nitrate medium. Also increased swelling of RHM(Na) energized with substrates in potassium acetate medium revealed that pinacidil increased potassium transport into matrix. Pinacidil stimulated oxygen consumption of RHM(Na) in State 4 and detained Ca 2+ -induced dissipation of ΔΨ mito . Under condition of Ca 2+ and Na + overload simulating ischemia/reperfusion, RHM(Na) oxygen consumption was not affected with pinacidil in State 3 and in the presence of 2,4-dinitrophenol. Cyclosporin A and ADP, the inhibitors of mitochondrial permeability transition pore (MPTP), markedly decreased Ca 2+ - induced swelling of RHM(Na) in nitrate ammonium or potassium acetate medium in the presence of pinacidil. Carboxyatractyloside, an inhibitor of cytosolic side-specific adenine nucleotide translocase, eliminated a pinacidil-stimulated oxygen consumption of succinate-energized RHMNa in State 4 regardless of the presence of Ca 2+ . Pinacidil was also concluded to accelerat potassium flux into energized RHM(Na) and promot MPTP opening in the low conduction state. Based on our data we suggested that the effect of pharmacological preconditioning induced by pinacidil could be due to it’s direct effect on mitochondria which is connected with above stimulation of the potassium permeability of the inner mitochondrial membrane and following reduce of the ΔΨ mito that thus prevent calcium overload of cardiomyocytes after ischemia/reperfusion in turn.

Experimental investigations of the effect the electrical conductivity of medium has on the performance of pH meters

Results from tests of pH meters carried out in ammonia media having low electric conductivity (less than 5.0 μS/cm) are presented. The check media for the tests were prepared in a special manner the use of which makes it possible to reproduce the pH value of solution with an error not exceeding ∼0.04pH in the range of electrical conductivities above 0.1 μS/cm. The instrument measurement error was determined at different electrical conductivities of medium. Different electrodes were tested, the majority of which were domestically produced ones intended for general industrial applications. Some results were also obtained for one dedicated electrode from a foreign manufacturer. The test results show that the instrument gives a biased pH value for such media. The bias has a random value, which nonetheless is stable in the majority of cases, depends on the electrical conductivity of medium being monitored, and may be quite essential for small electrical conductivities (0.5pH or more). A conclusion is drawn about the need to calibrate the instruments with respect to standard media having electrical conductivity close to that of the medium being monitored. Analytic relations characterizing the check media used fort tests (check solutions) are presented.

Engineering Pseudomonas protegens Pf-5 for Nitrogen Fixation and its Application to Improve Plant Growth under Nitrogen-Deficient Conditions

Nitrogen is the second most critical factor for crop production after water. In this study, the beneficial rhizobacterium Pseudomonas protegens Pf-5 was genetically modified to fix nitrogen using the genes encoding the nitrogenase of Pseudomonas stutzeri A1501 via the X940 cosmid. Pf-5 X940 was able to grow in L medium without nitrogen, displayed high nitrogenase activity and released significant quantities of ammonium to the medium. Pf-5 X940 also showed constitutive expression and enzymatic activity of nitrogenase in ammonium medium or in nitrogen-free medium, suggesting a constitutive nitrogen fixation. Similar to Pseudomonas protegens Pf-5, Pseudomonas putida, Pseudomonas veronii and Pseudomonas taetrolens but not Pseudomonas balearica and Pseudomonas stutzeri transformed with cosmid X940 showed constitutive nitrogenase activity and high ammonium production, suggesting that this phenotype depends on the genome context and that this technology to obtain nitrogen-fixing bacteria is not restricted to Pf-5. Interestingly, inoculation of Arabidopsis, alfalfa, tall fescue and maize with Pf-5 X940 increased the ammonium concentration in soil and plant productivity under nitrogen-deficient conditions. In conclusion, these results open the way to the production of effective recombinant inoculants for nitrogen fixation on a wide range of crops.

Effect of Dipeptides on In vitro Maturation, Fertilization and Subsequent Embryonic Development of Porcine Oocytes.

The effects of amino acids and dipeptides on in vitro production of porcine embryos and accumulation of ammonia in culture medium during developmental stages were examined in this study. The maturation, fertilization and development of embryonic cultures were performed in modified Tissue culture medium (mTCM)-199 supplemented with 10% (v/v) porcine follicular fluid, modified Tyrode’s albumin lactate pyruvate (mTALP) medium, and modified North Carolina State University (mNCSU)-23 medium, respectively. In addition, amino acids and dipeptides of different concentrations and combinations were used to treat the embryos. The addition of L-alanyl-L-glutamine (AlnGln)+L-glycyl-L-glutamine (GlyGln) significantly (p<0.05) improved oocyte maturation, fertilization and the incorporation and oxidation of 14C(U)-glucose when compared to the control group and other treatment groups. Additionally, 2–4 cell, 8–16 cell, morula and blastocyst development increased significantly (p<0.05) following treatment with AlnGln+GlyGln when compared to the control group and other treatment groups, while this treatment reduced the accumulation of ammonia. Taken together, these findings suggest that treatment with AlnGln+GlyGln may play an important role in increasing the rate of porcine oocyte maturation, fertilization and embryonic development by reducing the level of accumulated ammonia measured in the culture media.

Three-dimensional activated reduced graphene oxide nanocup/nickel aluminum layered double hydroxides composite with super high electrochemical and capacitance performances

The paper reported a three-dimensional activated reduced graphene oxide nanocup/nickel aluminum layered double hydroxides composite (3D-ARGON/NiAl-LDH) with super high electrochemical and capacitance performances. Graphene oxide was reduced by hydrazine in ammonia medium to form three-dimensional reduced graphene oxide nanocup using polystyrene colloidal particle as sacrificial template. The nanocup was then activated by the alkali corrosion and thermal annealing. The 3D-ARGON/NiAl-LDH was finally fabricated by the hydrothermal synthesis via in situ growth of ultrathin NiAl-LDH nanoflakes on the 3D-ARGON in an ethanol medium. The study demonstrated that the composite offers special 3D architecture with a macropore on the rim of a cup and large mesoporous structure on the wall of a cup, which will greatly boost the electron transfer and mass transport during the faradaic redox reaction, and displays excellent electrochemical and capactance performances, including high specific capacitance and rate capability, good charge/discharge stability and long-term cycling life. Its maximum specific capacitance was found to be 2712.7Fg−1 at the current density of 1Ag−1, which is more than 7-fold that of pure NiAl-LDH, 3-fold that of common reduced graphene oxide/NiAl-LDH and 1.8-fold that of two-dimensional activated reduced graphene oxide/NiAl-LDH. The specific capacitance can remain 1174Fg−1 when the current density increases up to 50Ag−1. After 5000 cycles at the current density of 30Ag−1, the capacitance can keep at least 98.9%. This study provides a promising approach for the design and synthesis of graphene-based materials with largely enhanced supercapacitor behaviors, which can be potentially applied in energy storage/conversion devices.

A Study of the Initial Stages of Co Deposition on a Silver Electrode in Ammonia Medium Using an Electrochemical Quartz Crystal Microbalance

The early stages of Co deposition on a silver electrode in ammonia medium were studied using cyclic voltammetry and chronoamperometry coupled with quartz crystal microbalance (EQCM) in ammonia solution. The results obtained by means of EQCM showed that during the initial stages of cobalt deposition a monolayer is formed on the substrate both in the underpotential and overpotential region, and this monolayer is formed at −600 mV and −980 mV. Once the cobalt deposition process starts, the growth is very fast making the investigation of the initial stages rather difficult. During this process, cobalt atoms transfer their two electrons through free species and not through cobalt hydroxide species adsorbed on the electrode as CoOH+ or Co(OH)2. In addition, it has been found that at potentials more positive than −600 mV, ammonia adsorption takes place on the substrate surface, and theses species are replaced when the cobalt atoms arrive at potentials more negative than −600 mV.

A Nitrate-Inducible GARP Family Gene Encodes an Auto-Repressible Transcriptional Repressor in Rice

Nitrogen is the most important macronutrient in plants and its supply induces responses in gene expression, metabolism and developmental processes. However, the molecular mechanisms underlying the nitrogen responses remain poorly understood. Here we show that the supply of nitrate but not ammonium immediately induces the expression of a transcriptional repressor gene in rice, designated NIGT1 (Nitrate-Inducible, GARP-type Transcriptional Repressor 1). The results of DNA-binding site selection experiments and electrophoretic mobility shift assays indicated that NIGT1 binds to DNA containing either of two consensus sequences, GAATC or GAATATTC. In transient reporter assays, NIGT1 was found to repress transcription from the promoters containing the identified NIGT1-binding sequences in vivo. Furthermore, NIGT1 repressed the activity of its own promoter, suggesting an autorepression mechanism. Consistently, nitrate-induced NIGT1 expression was found to be down-regulated after a transient peak during nitrate treatment, and the nitrate-induced expression of NIGT1 decreased in transgenic rice plants in which this gene was constitutively overexpressed. Furthermore, the chlorophyll content that could be a marker of nitrogen utilization was found to be decreased in NIGT1 overexpressors of rice grown with nitrate medium but not with ammonium medium. Thus, we propose NIGT1 as a nitrate-inducible and autorepressible transcriptional repressor that may play a role in the nitrogen response in rice. Taken together with the fact that the NIGT1-binding sites are conserved in promoter sequences of Arabidopsis NIGT1 homologs, our findings imply the presence of a time-dependent complex system for nitrate-responsive transcriptional regulation that is conserved in both monocots and dicots.

Spectral, Magnetic, Thermal, and DNA Interaction of Ni(II) Complexes of Glutamic Acid Schiff Bases

Ni(II) complexes with Schiff bases obtained by condensation of glutamic acid with salicylaldehyde; 2,3-; 2,4-; and 2,5-dihydroxybenzaldehyde; and o-hydroxynaphthaldehyde have been synthesized using the template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR, and 1H NMR spectra as well as thermal analysis (TG, DTG, DTA). The Schiff bases are dibasic tridentate or tetradentate donors and the complexes have square planar and octahedral structures. The complexes decompose in two or three steps where kinetic and thermodynamic parameters of the decomposition steps were computed. The interactions of the formed complexes with FM-DNA were monitored by UV and fluorescence spectroscopy.

Ni(II) complexes of arginine Schiff-bases and its interaction with DNA

Ni(II) complexes with Schiff-bases obtained by condensation of arginine with salicylaldehyde; 2,3-; 2,4-; 2,5-dihydroxybenzaldehyde and o-hydroxynaphthaldehyde have been synthesized using the template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR and 1H NMR spectra as well as thermal analysis (TG, DTG and DTA). The Schiff-bases are dibasic tridentate donors and the complexes have diamagnetic square planar and octahedral structures. The complexes decompose in three steps where kinetic and thermodynamic parameters of the decomposition steps were computed. The interactions of the formed complexes with FM-DNA were monitored by UV and fluorescence spectroscopy.

Isolation and Characterization of Heterotrophic Nitrifying Strain W1

In a high concentration substrate medium, a heterotrophic bacterium with high removal efficiency of ammonium, named W1, was isolated from activated sludge of coking wastewater treatment facility. The bacterium was Gram-negative, rod-shaped, and identified preliminarily as Alcaligenes sp. according to its morphological and physiological properties and its 16S rRNA gene sequence analysis. In the high concentration ammonium medium (400 mg·L−1 NH4+-N), the effects of C source, N source, C/N ratio and initial pH of medium on ammonium removal were investigated in order to determine the optimal condition for strain W1. The maximum ammonium removal was around 95% in 4 days in an improved medium. The production of N2 gas was examined in a closed system that was full of pure oxygen at the beginning. N2 gas was detected in the system after 4 days of cultivation, which further testified that strain W1 has heterotrophic nitrification and aerobic denitrification abilities simultaneously.