Effects Of Fe2 Research Articles

Reducing dissolution of MnO2 nanofibers by doping with ferric ion

MnO2 nanofiber was found to possess high adsorption capacities for heavy metal ions such as, arsenic and lead, in water due to its high specific surface area (SSA) and high surface activity. However, a significant amount of manganese was found to leach from MnO2 nanofibers. Reducing MnO2 dissolution is very important for improving its applications in drinking water treatment. In this study, MnO2 nanofiber was doped with Fe3+ to reduce its dissolution in water. Dissolution tests were conducted on un-doped and Fe-doped MnO2 nanofibers. The results revealed that doping with Fe3+ significantly reduced MnO2 dissolution. SSA and defects of MnO2 materials were analyzed by BET and XRD methods. The effects of Fe3+ on MnO2 dissolution were discussed and the optimal dopant amount was identified.

Magnetically loaded poly(methyl methacrylate-co-acrylic acid) nano-particles

Magnetically loaded polymeric nano-particles carrying functional groups on their surface were prepared by a two-stage process. In the first stage, super-paramagnetic magnetite (Fe3O4) nano-particles were produced by a co-precipitation method from the aqueous solutions of FeCl2·4H2O and FeCl3·6H2O using a NaOH solution. The smallest size obtained was 40.9 nm with poly-dispersity index of 0.194 obtained by using a Zeta Sizer. The effects of Fe2+/Fe3+ molar ratio, stirring rate, temperature, base concentration, and pH on the particle size/size distribution and stability of the dispersions were examined. Increasing the relative concentration of Fe2+ ion and decreasing the stirring rate and pH increased the particle size, while the concentration of NaOH and temperature did not change the particle size significantly. Polymer coating was achieved by emulsion polymerization at high surfactant to monomer ratio of methyl methacrylate (MMA) and acrylic acid which were used as comonomers (comonomer ratio: 90/10 weight) with high surfactant to monomer ratio. The surfactant and initiator were SDS and KPS, respectively. Nano-particles in the range of 115 and 300 nm in diameter were produced depending on recipe. Increasing the Fe3O4/monomer and surfactant/monomer ratios, the KPS concentration caused a decrease in the average diameter. Magnetic properties of the nano-particles were obtained by electron spin resonance and vibrating-sample magnetometer. Most of the polymer-coated nano-particles exhibited super paramagnetic behavior.

Optimization of Ionic and Chelated Iron and Its Interaction with Disodium Ethylenediaminetetraacetic Acid for Enhancement of Plant Regeneration in Rice (Oryza sativa L)

Interactive effects of Fe2(SO4)3 and Na2EDTA on callus induction and plant regeneration in indica rice (Oryza sativa cv Pusa Basmati-1) was investigated. Callus induction and subsequent plant regeneration from seed was obtained on MS medium supplemented with 11.31 µM 2,4-D and 2.68 µM NAA + 8.87 µM BAP respectively. Both the callus induction and the plant regeneration media were supplemented with different levels of Fe2(SO4)3, Na2EDTA and their combinations. Callus induction, its morphogenic potential, average number of regenerated plants as well as the appearance of the regenerants was influenced by the levels of Fe2(SO4)3 and Na2EDTA. Embryogenic callus could be induced in the presence of Fe2(SO4)3 / Na2EDTA. Iron was essential for plant regeneration. Non-chelated iron could induce callus formation as well as plant regeneration, yet the chelated form was more suitable. A higher level of Na2EDTA in the regeneration medium was detrimental. Differential requirement of Fe2(SO4)3 at induction and regeneration level was observed. Method of medium preparation affected the regeneration response. Nearly three fold increase in the number of regenerated plants was achieved with 0.05 mM Fe2(SO4)3 + 0.1 mM Na2EDTA at callus induction and 0.1 mM Fe2(SO4)3+ 0.1 mM Na2EDTA at plant regeneration and standard method of autoclaving.

Modulation of iron uptake in heart by L-type Ca2+ channel modifiers: possible implications in iron overload.

Heart failure is the leading cause of mortality in patients with transfusional iron (Fe) overload in which myocardial iron uptake ensues via a transferrin-independent process. We examined the ability of L-type Ca2+ channel modifiers to alter Fe2+ uptake by isolated rat hearts and ventricular myocytes. Perfusion of rat hearts with 100 nmol/L 59Fe2+ and 5 mmol/L ascorbate resulted in specific 59Fe2+ uptake of 20.4+/-1.9 ng of Fe per gram dry wt. Abolishing myocardial electrical excitability with 20 mmol/L KCl reduced specific 59Fe2+ uptake by 60+/-7% (P<0.01), which suggested that a component of myocardial Fe2+ uptake depends on membrane voltage. Accordingly, 59Fe2+ uptake was inhibited by 10 micromol/L nifedipine (45+/-12%, P<0.02) and 100 micromol/L Cd2+ (86+/-3%; P<0. 001) while being augmented by 100 nmol/L Bay K 8644 (61+/-18%, P<0. 01) or 100 nmol/L isoproterenol (40+/-12%, P<0.05). By contrast, uptake of 100 nmol/L ferric iron (59Fe3+) was significantly lower (1. 4+/-0.3 ng Fe per gram dry wt; P<0.001) compared with divalent iron. These data suggest that a component of Fe2+ uptake into heart occurs via the L-type Ca2+ channel in myocytes. To investigate this further, the effects of Fe2+ on cardiac myocyte L-type Ca2+ currents were measured. In the absence of Ca2+, noninactivating nitrendipine-sensitive Fe2+ currents were recorded with 15 mmol/L [Fe2+]o. Low concentrations of Fe2+ enhanced Ca2+ current amplitude and slowed inactivation rates, which was consistent with Fe2+ entry into the cell, whereas higher Fe2+ levels caused dose-dependent decreases in peak current. Fe3+ had no effect on current amplitude or decay. Combined, our data suggest that myocardial Fe2+ uptake occurs via L-type Ca2+ channels and that blockade of these channels might be useful in the treatment of patients with excessive serum iron levels.

Kinetic studies on oxidations of leucomethylene blue and leucothionine by iron (III) in aqueous solution

The reaction kinetics and mechanism of the oxidations of leucomethylene blue (MBH) and leucothionine (TH) by iron (III) sulfate in aqueous solution were studied spectrophotometrically by the stopped-flow technique. MBH and TH, which were freshly prepared by photoreduction of methylene blue and thionine, respectively, with ascorbic acid were used in the kinetic measurements. The pseudo-first-order rate constants (kobsd) show kinetic saturation at high initial concentrations of iron (III) sulfate for MBH and TH. It was found that the reciprocal of kobsd increases linearly with increase in the reciprocal of [Fe3+]0. A broad absorption band was observed on mixing MBH and Fe3+ solutions at low temperatures, and this was attributed to a charge-transfer complex between MBH and Fe3+. The effects of Fe2+ ion and L-(+)-ascorbic acid on the rates of oxidation were also investigated. A small kinetic isotope effect on the oxidation rate for MBH was observed. The results can be explained by a general mechanism with stepwise electron–proton–electron transfers with the formation of a complex between reactants. Copyright © 1999 John Wiley & Sons, Ltd.

Effects of Fe2+ and Fe3+ contents on cation ordering in omphacite

Effects of Fe2+ and Fe3+ contents on cation ordering in omphacite

Effect of Ferric Chloride on Silica Fouling

This study presents the results of an experimental investigation of the effects of Fe3+ ion in aqueous solution on silica fouling of heat exchanger and assesses the relative effect of Fe3+, Na+, and K+ ions on silica fouling. Experiments were conducted at 165–125°C, 1.58 MPa, and under turbulent flow conditions. It was shown that adding a few ppm of Fe3+ into silica solution was sufficient to formulate chemical coagulation and deposition of silica colloidal particles, which in turn caused a significant increase in the fouling rate. It was also observed that when Fe3+ was added to the silica solutions containing either Na+ or K+ ions, the fouling behaviors were found to be similar. Thus Fe3+ was found to be dominant over Na+ and K+ ions in its effects on silica fouling.

Purification and Some Properties ofα-Galactosidase fromCandida guilliermondiiH-404

Candida guilliermondii H-404, isolated from soil, produced thermostable α-galactosidase, but small amounts of other glycosidases (such as β-galactosidase, α-glucosidase, and β-glucosidase). The enzyme was separated into two fractions by DEAE-Toyopearl 650M chromatography, and the two enzymes were designated galactosidase I and II. These two enzymes had the same molecular weight (270,000 by gel filtration, 64,000 by SDS-PAGE). The isoelectric points of α-galactosidase I and II were 6.16 and 6.21, respectively. These two enzymes were different from each other in pH stability, temperature stability, and effects of Fe2 + and Cu2 + ion on α-galactosidase activity. The enzyme had stronger transfer activity and wider acceptor specificity than α-galactosidases which have been reported.

Effects of Fe3+ on electron spin echo signals in zeolites

The presence of paramagnetic Fe3+ impurities in zeolites can interfere with electron spin echo studies to decrease echo intensity. To study these effects Fe3+ as iron oxide and as structural Fe3+ was extracted from zeolites with an extraction procedure using ethylenediaminetetraacetic acid in the presence of aluminium nitrate. Comparison of electron spin echo signals of exchanged Cu2+ before and after iron extraction in X, Y and mordenite zeolites is reported. Commonly occurring quantities of Fe3+ influence both three-pulse and two-pulse echo signals by decreasing the echo intensity and by increasing the echo decay rate.

Effect of Cu2+ on Prostaglandin Synthesis and Catabolism in Rabbit Gastric Antral Mucosal Slices In Vitro.

The effects of Fe2+ and Cu2+ on prostaglandin (PG) synthesis and catabolism in rabbit gastric antral mucosal slices have been compared. Fe2+ markedly promoted the lipid peroxidation of gastric mucosal slices. The lipid peroxidation induced by Fe2+ inhibited the formation of all four PGs examined (PGE2, PGF2α, 13, 14-dihydro-15-keto PGE2 and 13, 14-dihydro-15-keto PGF2α) to a similar extent. While Cu2+ produced only a small increase in lipid peroxidation, it had a powerful stimulatory effect on PGE2 and PGF2α formation. Cu2+ induced no change in the formation of 13, 14-dihydro-15-keto PGE2 and 13, 14-dihydro-15-keto PGF2α. Moreover, tert-butyl hydroperoxide stimulated the formation of all four PGs at low concentrations (5 and 10μM), but inhibited it at a high concentration (1, 000μM). These results suggest that Cu2+ has the potential to increase the levels of biologically active PGs in gastric mucosa by affecting the activities of both PG cyclo-oxygenase and PG-catabolizing enzymes.

Crystal field and superposition model analysis for high-spin Fe2+ and Fe4+ ions in YBa2(Cu1-xFex)3O7- delta

Crystal field energy levels of Fe2+ and Fe4+ ions at several possible sites in YBa2(Cu1-xFex)3O7- delta namely, Cu(1) planar, pyramidal and octahedral sites, as well as Cu(2) sites, have been investigated. The superposition model formulae are developed to relate the crystal field parameters Bka with the available crystal structure parameters. The parameters Bka are calculated for Fe2+ and Fe4+ ions using the most likely values of the intrinsic parameters determined for crystal structures similar to that of YBa2Cu3O7. The crystal field energy levels and the ground states are then determined for Fe2+ and Fe4+ ions at each site. The superposition model enables the authors to also study the dependence of Bka and energy levels on the concentration (x) of Fe ions in YBa2(Cu1-xFex)3O7- delta . The ground state for most of the cases considered appears to be an orbital singlet with high spin S=2 and well separated from the excited 5D orbital levels due to the strong orthorhombic crystal field. This justifies application, in a subsequent paper, of the spin Hamiltonian analysis to gain further insight into the effects of Fe2+ and Fe4+ ions on the properties of high-Tc 123 superconductors.

Reaction characteristics of dental and synthetic apatites with Fe2 + and Fe3 + ions

Various effects of Fe2+ and Fe3+ ions on the reaction characteristics of dental and synthetic apatites have been investigated. It has been found that both Fe2+ and Fe3+ ions inhibit crystallization of calcium phosphates during the calcification process, and that the colour of the reaction product turns brown owing to the incorporation of these ions. The dental and the synthetic hydroxyapatites, the latter being a pure model substance of dental apatite, were also coloured when they were treated with Fe2+ solutions. The results show that Ca2+ ions in the apatites are exchanged for Fe2+ ions in solution and the ion-exchanged Fe2+ ions are partially oxidized to Fe3+ ions by dissolved oxygen in solution. Furthermore, the dissolution rate of the dental apatite treated with Fe2+ is inhibited in organic acid solution. For the reaction of the dental and the synthetic hydroxyapatites with Fe3+ ions, both the reaction rate and the removal of Fe3+ are far larger than those of Fe2+ and the product is a stable amorphous solid even in acidic solution of pH 3.0–5.0. These interesting phenomena are explained in terms of formation of an amorphous ferric phosphate hydrate by an attack reaction of Fe3+ ions in solution for Ca2+ ions of the apatite, assisted by the loosening effect of H+ ions on the skeletal structure of the apatite.

硫酸水溶液中における銅フェライトの溶解挙動に関する研究

In this research, dissolution of the synthesized copper ferrite in aqueous sulphuric acid was investigated where temperatures were varied from 323 K to 343 K, sulphuric acid concentration from 1 M to 3 M and experiment was done using a rotating disc system Effects of Fe3+, Fe2+ and SO42-were also studied. The experimental results have shown that, in the initial period of dissolution, rate of copper was greater than one of iron, leaving Fe203layer outside, and therefore, non stoichiometric dissolution of copper and iron. After long time of dissolution period, the stoichiometric dissolution of copper and iron was shown to be attained as described as follows: CuFe2O4+8H+=Cu++2Fe3++4H2OIncreases of temperature and acid concentration both lead to increase in dissolution rate of copper ferrite. However, increases in any of Fe3+, Fe2+ or SO42-decreased the dissolution rate, that has been discussed due to the decrease of hydrogen ion activity.

The Effects of Fe3 and Mn3 on Aluminum Silicate Phase Relations in North-Central New Mexico, U.S.A.

The Effects of Fe3 and Mn3 on Aluminum Silicate Phase Relations in North-Central New Mexico, U.S.A.

マグネシウム珪酸塩高圧相の構造

The structures of high-pressure phases of Mg2SiO4 and MgSiO3 are summarized based on the results of X-ray diffraction method using single crystals, and the relationships among their structures are discussed with configurations of polyhedra about cations. The α→β→γ phase transformations of Mg2SiO4, which are not accompanied with the change in coordination number of cations, are mainly characterized by the idealization and compression of MgO6 and _??_O6. The high-pressure phases of MgSiO3, ilmenite- and perovskite-types, have. SiO6 octahedra which show a slight expansion in the high-pressure phase. On the other hand, the coordination of Mg-polyhedra change remarkably in high-pressure phase. A linear correlation is observed between phase-transformation pressure and cation polyhedral volume. The Mg_??_Si disorder is not observed in any high-pressure phases of magnesiumsilicates. Effects of Fe2+ on the β- and γ-phase structures are also discussed.

Effects of Fe3+ binding on the microenvironments of individual amino groups in human serum transferrin as determined by differential kinetic labeling.

Effects of Fe3+ binding on the microenvironments of individual amino groups in human serum transferrin as determined by differential kinetic labeling.

O-82 - Effects of Fe2+, Cu2+ and adrenergic agents on membrane Na+, K+-ATPase activity from the central nervous system in various concentrations of Ca2+

O-82 - Effects of Fe2+, Cu2+ and adrenergic agents on membrane Na+, K+-ATPase activity from the central nervous system in various concentrations of Ca2+

Relation Between Initial Permeability and Fe2+ Ion of Mn-Zn Ferrite Systems

The effects of Fe2+ ion content on the initial permeability have been studied in Mn-Zn ferrites of various Mn/Fe ratios. The initial permeability and resistivity depend substantially on the Fe2+ ion content at. the regions containing a small excess of Fe2O3 over the stoichiometric composition.While, when additives are used, the relation between initial permeability and resistivity can not be simply compared to none additive ferrites.It was found that the values of initial permeability of Mn-Zn ferrite systems containing small amount of Te or MoO3 were strongly dependent on the Fe2+ ion content, but the resistivity values were nearly independent upon the presence of Fe2+ ions. The conduction mechanism of resistivity of the materials containing additives could not be explained on the theory of the electron transfer of Fe2+ ?? Fe3+ ion at the B-site in spinel lattice. Some explanations of these additive effects are presented.

Effects of Fe3+ on Corrosion of Iron in Acidic Solutions

Polarization curves of a platinum rotating disk electrode in acidic solutions containing Fe2+ and Fe3+ showed typical shapes of the diffusion-controlled process in both anodic and catholic directions. The process is governed by the diffusion of Fe3+ when the catholic reduction of Fe3+ couples the anodic dissolution of Fe because the anodic process is relatively fast under the given condition of the experiment. The corrosion test on iron rotating disks was carried out under various conditions. Some discussions on aqueous corrosion of iron in acidic solution containing Fe3+ as well as dissolved oxygen have been made.

Kinetics of vapour phase hydration of magnesium oxide. Part 3.—Effect of iron oxides in solid solution

The hydration of magnesiowustite, both ferrous and ferric types, containing 5 atom % iron was measured under identical conditions as in part 2 for MgO. Iron oxides in solid solution in MgO cause initial nucleation of the reaction to be greatly protracted. However, the remainder of the reaction for magnesiowustites of similar particle size follows reaction kinetics similar to those for MgO with respect to temperature and water vapour pressure. Activation energies for stoichiometric (i.e., ferrous), and non-stoichiometric (i.e., mainly ferric) magnesiowustites are 14.4 and 20.4 kcal/mole respectively. A “quasi-solution” mechanism is suggested for the hydration reaction of MgO and magnesiowustite governed by phase-boundary reaction kinetics. The progress of the phase-boundary reaction may be directly influenced by the effects of Fe2+ and Fe3+ on the MgO lattice.