Amount Of Iron Ions Research Articles

Formation of Iron Oxide Nanoparticles in the Internal Cavity of Ferritin-Like Dps Protein: Studies by Anomalous X-Ray Scattering

DNA-binding protein from starved cells (Dps) takes a special place among dodecamer mini-ferritins. Its most important function is protection of bacterial genome from various types of destructive external factors via in cellulo Dps–DNA co-crystallization. This protective response results in the emergence of bacterial resistance to antibiotics and other drugs. The protective properties of Dps have attracted a significant attention of researchers. However, Dps has another equally important functional role. Being a ferritin-like protein, Dps acts as an iron depot and protects bacterial cells from the oxidative damage initiated by the excess of iron. Here we investigated formation of iron oxide nanoparticles in the internal cavity of the Dps dodecamer. We used anomalous small-angle X-ray scattering as the main research technique, which allows to examine the structure of metal-containing biological macromolecules and to analyze the size distribution of metal nanoparticles formed in them. The contributions of protein and metal components to total scattering were distinguished by varying the energy of the incident X-ray radiation near the edge of the metal atom absorption band (the K-band for iron). We examined Dps specimens containing 50, 500, and 2000 iron atoms per protein dodecamer. Analysis of the particle size distribution showed that, depending on the iron content in the solution, the size of the nanoparticles formed inside the protein molecule was 2 to 4 nm and the growth of metal nanoparticles was limited by the size of the protein inner cavity. We also found some amount of iron ions in the Dps surface layer. This layer is very important for the protein to perform its protective functions, since the surface-located N-terminal domains determine the nature of interactions between Dps and DNA. In general, the results obtained in this work can be useful for the next step in studying the Dps phenomenon, as well as in creating biocompatible and solution-stabilized metal nanoparticles.

Cytotoxicity of a Cell Culture Medium Treated with a High-Voltage Pulse Using Stainless Steel Electrodes and the Role of Iron Ions.

High-voltage pulses applied to a cell suspension cause not only cell membrane permeabilization, but a variety of electrolysis reactions to also occur at the electrode–solution interfaces. Here, the cytotoxicity of a culture medium treated by a single electric pulse and the role of the iron ions in this cytotoxicity were studied in vitro. The experiments were carried out on mouse hepatoma MH-22A, rat glioma C6, and Chinese hamster ovary cells. The cell culture medium treated with a high-voltage pulse was highly cytotoxic. All cells died in the medium treated by a single electric pulse with a duration of 2 ms and an amplitude of just 0.2 kV/cm. The medium treated with a shorter pulse was less cytotoxic. The cell viability was inversely proportional to the amount of electric charge that flowed through the solution. The amount of iron ions released from the stainless steel anode (>0.5 mM) was enough to reduce cell viability. However, iron ions were not the sole reason of cell death. To kill all MH-22A and CHO cells, the concentration of Fe3+ ions in a medium of more than 2 mM was required.

Тенденция изменения качества воды главного Ширванского коллектора за многолетний период

The article examines the tendency of changes in the hydrochemical regime of the water of the Main Shirvan collector over a long period of time and the suitability of the collector water for irrigation. Continuous laboratory analyzes performed between 2004 and 2019 were compared to 1986. According to experimental data, it was determined that the hydrochemical regime of the collector water is gradually improving, and the salt content is decreasing. The degree of mineralization of the collector water decreased by 2.3 times, the total hardness by 2.2 times, the number of chloride ions by 10.5 times, the number of calcium ions by 1.3 times, the number of magnesium ions by 2.8 times, the total number of cations sodium and potassium decreased by 3.9 times. For 2004–2019 biochemical oxygen consumption in collector water increased 7.9 times, chemical oxygen demand increased 7.5 times, and the number of suspended particles increased 9 times. The amount of iron ions in water decreased by 2 times, while the amount of aluminum and zinc did not change. The suitability of collector water for irrigation was determined according to 7 internationally accepted assessment criteria. Collector water is considered suitable for irrigation in accordance with 6 assessment criteria — the degree of salinity, irrigation coefficient, sodium sorption coefficient, potential salinity, water alkalinity index and percentage of sodium, as well as 1 criterion not suitable for irrigation — the percentage of magnesium. Collector water can be used to irrigate crops.

Electrochemical oxidation of 2,4,6-trichlorophenol on iron-doped nanozirconia ceramic

Solvothermaly synthesized zirconium oxide nanopowders, pure and doped with various amounts of iron ions (1?20 %), were used as modifiers of glassy carbon electrodes. The modified electrodes were tested in the reaction of electrochemical oxidation of 2,4,6-trichlorophenol (TCP) in order to investigate the influence of doping on electrochemical performance of zirconia matrix. The techniques of cyclic voltammetry and electrochemical impedance spectroscopy were employed. Cyclic voltammetry showed that electrooxidation of TCP proceeded through the oxidation of hydroxyl group. Possible pathway included the formation of quinones and the formation of polyphenol film on the electrode surface, leading to the electrode fouling. Iron doping enhanced the activity of zirconia matrix towards TCP electrooxidation. Electrochemical impedance spectroscopy showed the importance of iron content in zirconia matrix for the preferable pathway of TCP electrooxidation. The quinone formation pathway was favoured by low iron doped zirconia (doped with 1% of iron), while polyphenol film formation on the electrode surface was more pronounced at samples with higher iron ion content (for doping with 10 and 20 % of iron). The sample with 5 % of added iron ions, showed intermediate behaviour, where the formed polyphenol film showed slight degradation.

PO-295 Effect of resveratrol on preventing iron overload in liver of mice

Objective To investigate the mechanism of resveratrol improving iron overload in liver of mice and its effect on alleviating liver oxidative damage.
 Methods 40 male Balb/Cj mice, 2 months old, were randomly divided into 4 groups, Quiet control group (group C), sucrose iron group (group I), resveratrol group (group R), resveratrol + sucrose iron group (group IR), 10 in each group. Group IC and group IR were intraperitoneally injected with sucrose iron solution (100mg/5mL) once every two days, 75uL each time; R group and IR group were intragastrically resveratrol (Res), dissolved in 1% DMSO solution, each time 30mg / Kg; Group C and IC group were intragastrically administered with 1% DMSO solution once daily for 30 mg/Kg. After the end of the intervention for 8 weeks, the mice were dissected and taken. Perls' staining was used to observe the distribution of iron in the liver of mice; biochemical kit for serum glucose, serum iron (SI), total iron binding capacity (TIBC), liver iron, liver superoxide dismutase (T-SOD), liver malondialdehyde (MDA), total liver oxidative capacity (T-AOC); enzyme-linked immunosorbent assay (ELISA) for detection of serum ferritin (SF), octahydroxydeoxyguanosine (8-OHdG); Western blot detection of FPN1 protein expression in liver; the expression of Hepcidin in liver was detected by PCR.
 Results (1) Perls' staining results: 8 weeks of iron sucrose caused a significant increase in iron content in mouse hepatocytes, and Res decreased the amount of iron ions in hepatocytes; (2) Results of iron metabolism index: 8 weeks of sucrose iron had a significant increase in liver iron, SI, TIBC and SF (P<0.01), and Res intervention reduced liver iron (P<0.05) and SF (P<0.01). The content of TIBC (P<0.01) and SI (P<0.05) increased, and the iron supplement and Res interacted with the effects of liver iron, SI and TIBC; (3) Results of glucose metabolism index: iron overload increased glucose level in mice (P<0.01), Res decreased glucose level, iron overload reduced liver glycogen storage in mice (P<0.05), iron supplement and Res, there is no interaction on the effects of glucose metabolism indicators; (4) Oxidation index results: 8 weeks of sucrose iron significantly inhibited liver T-SOD and T-AOC activity (P<0.01), increased liver MDA and 8-OHDG activity (P<0.01), and Res promoted liver T-AOC (P<0.01) and T-SOD activity increased, and the liver 8-OHDG (P<0.01) and liver MDA activity were decreased. The effects of iron supplement and Res on 8-OHDG and T-AOC were interactive (P<0.01); (5) 8 weeks of sucrose iron inhibited the expression of FPN1 protein in the liver of mice, and the intervention of Res could enhance the expression of FPN1 protein; iron supplement promoted the expression of Hepcidin in liver (P<0.01), Res inhibited Hepcidin, iron supplement and Res had no interaction with the expression of FPN1 and Hepcidin in liver.
 Conclusions 8 weeks of sucrose iron caused iron overload in the liver of mice, and increased oxidative stress in the liver. Res can alleviate iron overload, reduce oxidative stress and improve glucose metabolism. The main reason is that Res inhibits Hepcidin expression in liver and promotes FPN1 expression and promotes The liver iron is released, thereby reducing the state of iron deposition.

Oxidation/elimination of heterocyclic sulfur compounds in a biphasic system with mesostructured FeOx/Ti-MCM-41 catalysts

A series of FeOx/Ti-MCM-41 mesostructured catalysts were synthesized and characterized by the X-ray diffraction (XRD), N2 adsorption-desorption isotherms, transmission electron microscopy (TEM), and Mössbauer spectroscopy. The surface reducibility and acidity of the catalysts were measured by temperature-programmed reduction of hydrogen (TPR-H2) and temperature-programmed desorption of ammonia (TPR-NH3) methods. Incorporating Ti4+ in the MCM-41 framework and loading Fe2O3 in the surface of the catalysts would create the acid sites and enhance the surface oxygen reducibility. Most of Fe3+ ions were highly dispersed on the surface and some were inserted into the framework of the support with different structural environments. The amount of the Fe3+ ions locating around the structural defects increased as the Fe content increased. In a biphasic reaction system (n-hexadecane/acetonitrile), the oxidation/elimination of dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) could correlate perfectly with the surface acidity and the amount of iron ions around the structural defects of the catalysts. The reactivity of sulfur compounds decreased with increasing of the steric hindrance, showing an order as: DBT>4-MDBT>4,6-DMDBT. In the presence of catalyst and oxidant, the polar/non-polar biphasic reaction system developed herein could effectively oxidize the sterically hindered sulfur compounds and simultaneously extracted the produced sulfones from oil phase into polar phase.

15N solid-state nuclear magnetic resonance study of pyrolyzed metal-polyaniline cathode catalysts for oxygen reduction in fuel cells

The oxygen reduction reaction (ORR) activity of pyrolyzed metal-free and metal (Mn, Fe, Co, Ni and Cu)-containing polyaniline (PANI) in polymer electrolyte fuel cell (PEFC) was studied. The metal-free PANI800 shows quite poor ORR catalytic activity, whilst the metal-containing PANIMe800 display a better ORR activity. The 15N CP/MAS NMR spectra of PANINi800 and PANICu800 show one weak peak at 118 ppm and there is no peak observed in PANIFe800, against that of PANI800, PANIMn800, PANICo800 and PANINi800 show two peaks at 273 and 118 ppm assigned to the pyridinic and pyridinium nitrogens. It is because of the paramagnetic effect of metal ions. The 15N spin-echo NMR spectra of PANIMe800 with fast recycle delay show the peaks at 140 and 270 ppm assigned to the graphitic and pyridinic nitrogens, against that of PANI800 shows no peak. The spectra of PANIMn800, PANICo800, PANINi800 and PANICu600 also contain a very broaden peak at 430 ppm assigned to the nitrogen with Fermi-contact effect from metal ions. The spectra of PANIFe800 show some spinning side bands and the average Fe3+–15N distance can be calculated. The some amount of iron ion are relieved and average Fe3+–15N distance increase after acid washing and the ORR activity decreases.

Optimizing Phenanthrene and Anthracene Oxidation by Sodium Persulfate and Fe-Modified Diatomite Using the Response Surface Method

This study proposes an improved activation for hydrogen peroxide and persulfate using Fe-modified diatomite (MD) to favorably lead the reaction to generate hydroxyl and sulfate radicals to degrade the contaminants phenanthrene and anthracene. Diatomite was modified by impregnating it with a mixture of ferrous (Fe2+) and ferric (Fe3+) ions in the form of precipitated iron oxides and hydroxides. The raw and synthesized materials were characterized by powder X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size by laser diffraction, chemical microanalysis of the elements by energy-dispersive X-ray, and scanning electron microscopy (SEM). Batch experiments were performed to compare the new activator material (modified diatomite) with traditional methods of activation for these oxidants and to statistically study the optimum ratio between the amount of this material and the concentration of one oxidant to the degradation of the contaminants phenanthrene and anthracene. The characterization results showed that the materials are amorphous and that the Fe ion concentration was 4.78 and 17.65 % for the raw and modified diatomites, respectively. This result shows a significant increase in the amount of iron ions after synthesis. Comparing the traditional activation method with the modified diatomite, the results of batch experiments showed that the synthesized material presents significant catalytic activity for the oxidation of these contaminants, using sodium persulfate and hydrogen peroxide as oxidants. The analysis of the variables results showed that the concentration of the oxidant has higher significance than the amount of the catalyst.

Inhibition efficiency of aminobenzonitrile compounds on steel surface

The aim of this study is to investigate the inhibition efficiency of benzonitriles with functional amine groups in different positions, for mild steel corrosion in 0.5M HCl solution. For this purpose, electrochemical impedance spectroscopy and potentiodynamic measurements were realized. Besides, these electrochemical analyses were carried out at different temperatures in order to obtain temperature dependency of inhibition efficiency. By using atomic absorption spectroscopy techniques, the amount of iron ions that released to the solution was determined, during immersion time. The surface analysis was also carried out by scanning electron microscopy technique. The results show that all these inhibitors have a good inhibition effect on mild steel in 0.5M HCl solution, and it depends on the position of amine group.

The identification of a vacuolar iron transporter involved in the blue coloration of cornflower petals

The blue petal color of the cornflower (Centaurea cyanus) is caused by protocyanin, a kind of metalloanthocyanin, which is a self-assembled supramolecular metal complex pigment. Protocyanin is composed of six molecules of anthocyanin, six molecules of flavone, one ferric ion, and one magnesium ion. The ferric ion is essential for blue color development. Here, we identify the vacuolar iron transporter gene (CcVIT) from the blue petals of C. cyanus and its function is identified and characterized. The CcVIT transcript was observed only in the petals. Its amino acid sequence is highly homologous to the Arabidopsis thaliana (AtVIT1) and Tulipa gesneriana (TgVit1) vacuolar iron transporters. Heterologous expression of the CcVIT gene in yeast indicated that the corresponding gene product transports ferrous ion into vacuoles. Analysis of purple mutant-line petals clarified that the anthocyanin and flavone components were the same as those found in plants with blue petals, but the amount of iron ions in the colored cells decreased, and consequently the amount of blue protocyanin was reduced. The CcVIT gene was expressed even in purple mutant petals, however, an amino acid substitution (A236E) occurred in that case. This change in the CcVIT gene sequence also resulted in loss of iron transport activity. The CcVIT protein thus plays a critical role in the blue coloration of cornflower petals.

Effects of iron ion contents on composition, morphology, structure and properties of chromium coatings electrodeposited from novel trivalent chromium sulphate electrolyte

Chromium coatings were electrodeposited from a novel trivalent chromium sulphate electrolyte using oxalate as the complexing agent. Energy dispersive spectroscopy, Scanning electron microscopy, X-ray diffraction, Tafel curve, and X-ray photoelectron spectroscopy techniques were used to characterise the compositions, surface morphologies, structures, corrosion resistances, and element chemical states of the coatings. The effects of Fe2+ ions were investigated in detail. Results show that the small amount of iron ions generated coatings containing iron. The coating obtained is actually a Cr–Fe alloy of solid solution structure and microcrack surface morphology. X-ray photoelectron spectroscopy study revealed that a thin Cr(III) oxide film was formed on the surface of the coatings, and Cr(s) and Fe(s) states were observed within the coatings. As Fe2+ ion contents were increased in the electrolyte, the iron content of the coatings significantly increased. The electrodeposited coatings exhibited a crack-free surface morphology when Fe weight content exceeded 30·1%. The coating with 26·3 wt-%Fe had an amorphous structure and the lowest electrochemical activity.

A wood-based fibrous chemisorbent

A method and the conditions for fabricating a fibrous chemisorbent by graft polymerization of acrylamide on pine wood in the presence of a Fe 2+ —H 2 O 2 redox initiating system were developed. The maximum values of the yield of commercial copolymer (76.79%) and mass fraction of the graft component (53.49%) were attained at a 0.017 wt. % concentration of H 2 O 2 , 1.5% monomer, temperature of 60°C, and process time of 1 h. The process takes place with 97.85% efficiency and insignificant formation of homopolymer (1.4%). The sorption and kinetic properties of the samples with respect to mercury ions were established. It was found that sorbent with a 9.93% nitrogen content extracts 65-64% of Hg(II) ions from dilute and concentrated solutions and is equal to the industrial strongly acid sulfo cation exchanger Ky-2x8. Based on the data from IR spectroscopy and the linear anamorphoses of equilibrium sorption isotherms, the chemisorption mechanism of absorption of mercury(II) ions by wood with graft amide groups was established. Graft polymerization of unsaturated nitrogen-containing monomers, acrylamide (AA) in particular, on different natural matrices, for example, lignin, coconut shells, starch, and especially cellulose [1-4], has been relatively widely treated in scientific publications. However, the studies on synthesis of graft amino copolymers based on wood are limited. Moreover, modification of such lignocellulosic material with chemically active monomers, where it is possible to create fibrous ion exchangers that differ from ordinary sorbents by smaller geometric dimensions and developed external surface which determine their high capacity and kinetic characteristics, is very pressing. We synthesized a graft copolymer of wood and AA (Wd-AA) and studied its sorption properties with respect to mercury(II) ions. Air-dried pine sawdust of the 2 mm screen sizing fraction containing (in wt. %) 48.3% cellulose, 17.6% hemicellulose, 28.6% lignin, 5.0% extractives, 0.52% ash (including 0.48% insoluble and 0.04% water-soluble residue; pH of ash of 4.72) was used for modification. The elemental composition of the wood was (in %): 45.63 C, 6.10 H, 47.40 O, 0.87 N; moisture content of 9.85; dryness coefficient of 0.9015. Graft polymerization was conducted with the Fe 2+ —H 2 O 2 redox initiating system. The wood was held in a solution of Mohr’s salt with a 7.09 mg/liter concentration of Fe 2+ at pH = 5 and after washing off the excess metal ions, immersed in an aqueous solution containing a different amount of monomer and H 2 O 2 . The concentration of Fe 2+ in the polymer matrix was 2.52 mg/g. The product was purified of homopolymer — polyacrylamide (PAA) and unreacted AA with distilled water in a Soxhlet apparatus. The amount of ungrafted polymer was determined gravimetrically after precipitation of PAA from aqueous solution into ethanol or evaporation of the solution at low pressure. The characteristics of the graft copolymer and grafting parameters were: mass content of PAA in modified wood (W), degree of conversion of AA into homo-, graft polymer (C hp , C g ); the total conversion of monomer (C t ), grafting percentage (P g ) and efficiency (G E ) were calculated according to [5, 6]. The content of amide groups in the reaction products (E N ) was determined by titration with an accurate weighed portion of samples in a solution of acetic anhydride with 0.1 N solution of HClO 4 in glacial acetic acid. The amount of iron ions adsorbed in the polymer phase was established by atomic-absorption analysis and the nitrogen content in the graft copolymers was determined chromatographically. Sorption of Hg(II) was conducted in static conditions from 20 ml of a solution of Hg(NO 3 ) 2 ⋅2H 2 O (analytically pure) with copolymer weighing 0.05 g. The initial and equilibrium concentrations of metal ions in the solution was determined by

Fretting corrosion resistance and fretting corrosion product cytocompatibility of ferritic stainless steel.

To avoid nickel ion release from SUS317L as an implant material, a new type of nickel, commercially free, of high purity, and high chromium ferritic stainless steel, was developed. The new stainless steel (FJ) was studied for aspects of fretting corrosion and cytocompatibility compared with SUS317L. A pin-on-plate fretting corrosion test in an artificial physiologic solution, and cell culture in media with the addition of the artificial physiologic solution used for fretting was conducted. Resistance to the fretting induced crevice corrosion of FJ was higher than that of SUS317L because of the favorable electrochemical stability of the FJ alloy. The amount of iron ion or colloidal fine particles released from FJ was about a quarter of that from SUS317L, although the weight loss of a pin of FJ was almost 5/3 that of SUS317L. The artificial physiologic solution used for SUS317L fretting was more harmful to the growth of L929 and MC3T3-E1 cells than that used for FJ fretting. FJ was therefore superior to SUS317L as a biomaterial, judging from the resistance to fretting-induced crevice corrosion, electrochemical stability, and the cytocompatibility of fretting corrosion products.

Effect of Temperature and Dissolved Oxygen on the Corrosion Behavior of Carbon Steel in High-Temperature Water

Abstract The corrosion behavior of carbon steel in high-temperature water, and the structure and composition of the oxide film were examined as functions of dissolved oxygen concentration (DO), temperature (T), and corrosion time (t). The total amount of iron corroded (WT) was differentiated into the amounts of iron ions in the oxide (WF) and dissolved into the water (WD). The total rate of corrosion (rT), the rate of iron dissolution (rD), and the rate of accumulation of iron in the oxide (rF) were obtained by differentiating the time variations in WT, WF, and WD. The structure and composition of the oxide film were examined by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and transmission and scanning electron microscopy. In general, rT increases with increasing DO and T, rD shows T- and DO-dependent minimum, and there is serious localized corrosion at high DO above 500 ppb. Oxide films consist of magnetite except at T=60°C, DO=50 to 200 ppb where a thin layer of hydrous ferric oxide is formed. At DO=500 ppb , the outermost part of the magnetite changes into γ-Fe2O3, and above DO=1.0 ppm, appreciable amounts of α-Fe2O3 cover the magnetite oxide layer. The rT and rD values are not related to the presence of αFe2O3 or Fe3O4 in the surface structure of the oxide, but clearly decrease as the OH−/Fe mole ratio at the oxide surface increases. The mechanism determining the corrosion rate changes is discussed.