Range Of Iron Concentrations Research Articles

Geochemical and mineralogical heterogeneity of the Cantung mine tailings: implications for remediation and reprocessing

Reprocessing tailings to recover minerals of economic interest and environmental concern can add value to a project and decrease environmental risk, but dealing with heterogeneity within tailings facilities is a challenge. This study investigates the heterogeneity of the Cantung Mine tailings to assess the potential for reprocessing for both value recovery and remediation purposes. The Cantung Mine, Northwest Territories, was a world-class tungsten (W) deposit that was mined periodically from 1962 to 2015. Geochemical analysis of 196 tailings samples shows substantial heterogeneity in the elements of value (tungsten and copper (Cu)) and elements of environmental concern for acid rock drainage (iron (Fe) and sulfur (S)). Tungsten and copper concentrations range from 0.06 to 1.06 wt% W (average 0.32 wt% W) and 0.05 to 0.48 wt% Cu (average 0.23 wt% Cu). Iron and sulfur concentrations range from 8.25 to 34.08 wt% Fe (average 17.14 wt% Fe) and 2.20 to 19.70 wt% S (average 6.7 wt% S). Characterization of 29 samples by scanning electron microscope with automated mineralogy software shows that geochemical heterogeneity corresponds to mineralogical heterogeneity with variability in the concentrations of scheelite (CaWO4), chalcopyrite (CuFeS2) and pyrrhotite (Fe(1-x)S). Liberation analyses indicate that additional grinding would be necessary to recover scheelite, chalcopyrite or pyrrhotite. Pyrrhotite with monoclinic and hexagonal-orthorhombic forms were identified. Overall, the Cantung tailings display considerable heterogeneity, which could lead to difficulties in reprocessing for economic or environmental benefit, but characterizing the heterogeneity allows for systems to be optimized.

Correlation between serum iron levels and pulmonary function: A cross-sectional analysis based on NHANES database 5319 cases.

Pulmonary function, one of the main indicators of respiratory system assessment, is difficult to measure in specific cases. The study investigated the association between serum iron levels and pulmonary function. The cross-sectional study was conducted using data from 5319 participants from the 2010-2012 National Health and Nutrition Examination Survey. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and forced expiratory flow from 25% to 75% of FVC were used as indicators of pulmonary function to analyze the relationship of serum iron and pulmonary function. Univariate and stratified analyses, multiple equation regression analysis, smoothed curve fitting analysis, and threshold effect analysis were performed to explore the relationship between pulmonary function and serum iron concentrations. Threshold effect analysis revealed a nonlinear relationship between serum iron levels and FVC, as well as FEV1, with inflection points observed at 8.1 (µmol/L) and 8.4 (µmol/L), respectively. When serum iron concentrations fell below the inflection point, there was no statistically significant relationship between serum iron and FVC (P = .065) or FEV1 (P = .095) (P > .005). However, when serum iron concentrations exceeded the inflection point, both FVC (β = 6.87; 95% confidence interval [CI] = 3.95, 9.79; P < .0001) and FEV1 (β = 7.09; 95% CI = 4.54, 9.64; P < .0001) exhibited a positive correlation with increasing serum iron levels. Additionally, forced expiratory flow from 25% to 75% of FVC (mL/s) demonstrated a positive association with serum iron (β = 6.72; 95% CI = 2.30, 11.13; P = .0029). Serum iron level was positively correlated with pulmonary function within a certain range of serum iron concentration. Serum iron level may be a protective factor for pulmonary function.

Development of facile field-test paper for rapid determination of iron contamination in natural water of acid sulfate soils

Abstract The iron concentration in natural water of acid sulfate soils is usually determined by complicated methods of SMEWW 3111B:2017 or ISO 6332: 1988 E in the laboratory for acidified water samples at pH ∼2–3. Therefore, the rapid field determination of iron content in natural water is a very useful method because it limits the error and reduces the experimental time for analysis. In this study, we proposed, developed, and tested a rapid colorimetric analysis method based on the chemical reaction of ferric and anion thiocyanate (SCN−) ions for an iron concentration range of 0–100 mg/L with a linear equation of ΔE = 0.5955x + 2.0909 and high correlation coefficient (R2) of 0.9864. The results from 10 water samples by this method were very close to those by flame absorption spectroscopy with a difference of less than 5%. Besides the biggest advantage of rapid site testing, this method also gives quite high accuracy compared to the molecular absorption method of ISO 6332:1988 E. In addition, this new method can quantify Fe3+, Fe2+, and total iron in water, suggesting a very useful and potential method for determining the iron content of natural water from acid sulfate soils.

Advances in iron(III) hydrolysis studies. Effect of the metal concentration, ionic medium and ionic strength

The hydrolytic behaviour of iron(III) was studied in absence and in presence of different salt solutions, in the ionic strength range: 0 < I/moldm−3 ≤ 1.0 in NaNO3(aq) and NaClO4(aq), and 0 < I/moldm−3 ≤ 3.0 in NaCl(aq), at T = 298.15 ± 0.15 K, by means of potentiometry and UV–Vis spectrophotometry (only in NaClO4). The two techniques allowed to perform the study in a wide range of iron(III) concentration: 2.5 ≤ cFe3+/mmoldm−3 ≤ 195.6 for the first, while 0.04 ≤ cFe3+/mmoldm−3 ≤ 0.25, for the second one. The results obtained by potentiometric measurements in NaNO3(aq) and NaCl(aq), allowed to determine the speciation model: Fe(OH)2+, Fe(OH)2+, Fe2(OH)24+, Fe3(OH)45+ and Fe12(OH)342+. In the case of the spectrophotometric titrations in NaClO4(aq), the best results were obtained considering the species: Fe(OH)2+, Fe(OH)2+ and Fe(OH)3(aq); for each one, the molar absorptivity values were calculated at the various experimental conditions investigated. The dependence on the ionic strength of the hydrolytic constants was modelled by means of Debye-Hückel type equation and of the Specific ion Interaction Theory. The differences of the hydrolytic constants in NaCl(aq) and NaNO3(aq) were interpreted in terms of different interactions of the Fe3+ with the anions of the supporting electrolyte. This interaction can be neglected when a not interacting medium as NaNO3(aq) is used. This consideration allowed to extrapolate the formation constants at infinite dilution of the weak FeCl2+ and FeCl2+ complexes; by using experimental data, it was also possible to calculate the equilibrium constant of the mixed FeOHCl+ species.

Encapsulation of atomized erythrocytes in liposomes as source of heme iron for oral supplementation strategies

AbstractThis work aimed to develop and characterize liposomes of atomized bovine erythrocytes (ABE‐liposomes) for potential use as a heme iron supplement or to fortify food with heme iron. Soy lecithin (SL) and Tween 80 (T80) were chosen to prepare empty liposomes (8 types), and ABE‐liposomes (16 types) by a rotary‐evaporated film method. Variables of interest for our study were: ABE concentration, proportion of SL:T80 and ultrasonic bath time. ABE‐liposomes were characterized according to appearance, color, morphology, Fourier transform infrared spectroscopy (FTIR), size, zeta potential, total iron content, encapsulation efficiency (EE) and in vitro iron release under gastrointestinal conditions. ABE‐liposomes presented a brown color and spherical shape. Hydrogen bridges were the main interactions in ABE‐liposomes. Their size ranged from 379 to 964 nm, the zeta potential from −56 to −74 mV, the iron concentration range was 0.8–9.0 mg/100 mL, and EE ranged from 29% to 48%. Ultrasonic bath time was the most important variable on the reduction of ABE‐liposomes' size and EE. Under in vitro gastrointestinal conditions, iron release from ABE‐liposomes occurred mainly at the intestinal level. In conclusion, ABE‐liposomes were effectively developed, which could become a complement for supplementation or food fortification strategies with nonheme for the prevention of iron deficiency anemia.Practical ApplicationsIn this study atomized bovine erythrocytes (ABE)‐liposomes were developed, due to the: (1) lack of supplements or products to fortify foods based on heme iron, (2) higher bioavailability of heme iron than nonheme iron, especially when working with ABE, and (3) ABE is a low value‐added product that is generated in slaughter plants and in turn is an excellent source of underutilized heme iron. In this study it was possible to develop ABE‐liposomes, where ABE was encapsulated inside liposomes, obtaining a product that could be used as a complement in iron supplementation strategies or food fortification to prevent or treat iron deficiency or iron deficiency anemia, especially in developing countries that have low consumption of heme iron.

Bio-Accumulation of Heavy Metals in Aquatic Organism in Otamiri River in Owerri, Imo State, Nigeria

Depending on a number of variables, heavy metals from both natural and anthropogenic sources may accumulate in fish bodies and heads in aquatic environments. This study intends to evaluate the degree of heavy metal bioaccumulation in Tilipia fish from the Otamiri river. A sample of dry tissue weighing around one gram was weighed, placed into polyethylene tubes, and treated with 8 ML of nitric acid and 4 ML of perchloric acid. An atomic absorption spectrophotometer was used to determine the presence of heavy metals in the fish tissues. The amount of heavy metals present in fish sections was listed as follows: Lead varies from 32.00-7.23mg/kg, and the greatest value was found in the fish head that was caught in the Otammiri River. Zinc ranges from 16.75 mg/kg to 17.13 mg/kg, with the highest value recorded in the fish head. Copper concentrations range from 1.50 to 5.43 mg/kg, and iron concentrations range from 67.25 to 90.58 mg/kg, with the greatest value found in fish heads. Nickel ranges from 5.78 to 13.90mg/kg and cadmium ranges from 1.38 to 3.68mg/kg; the fish head has the highest concentration of these elements. The region of the fish's head was discovered to have the highest concentration of all the heavy metals. This is due to the fact that the fish's gills are the first organs to be exposed to heavy metal exposure and are a significant site for heavy metal intake. However, when the levels of heavy metals in the fish from this Rivers was compared to the WHO's tolerable standard, the concentrations were significantly higher, raising serious concerns because, by all accounts, the Otammiri River is highly contaminated and these fish could have a negative impact on human health if consumed. Therefore, steps should be done to prevent additional River contamination.

Data adaptive regularization with reference tissue constraints for liver quantitative susceptibility mapping.

To improve repeatability and reproducibility across acquisition parameters and reduce bias in quantitative susceptibility mapping (QSM) of the liver, through development of an optimized regularized reconstruction algorithm for abdominal QSM. An optimized approach to estimation of magnetic susceptibility distribution is formulated as a constrained reconstruction problem that incorporates estimates of the input data reliability and anatomical priors available from chemical shift-encoded imaging. The proposed data-adaptive method was evaluated with respect to bias, repeatability, and reproducibility in a patient population with a wide range of liver iron concentration (LIC). The proposed method was compared to the previously proposed and validated approach in liver QSM for two multi-echo spoiled gradient-recalled echo protocols with different acquisition parameters at 3T. Linear regression was used for evaluation of QSM methods against a reference FDA-approved -based LIC measure and measurements; repeatability/reproducibility were assessed by Bland-Altman analysis. The data-adaptive method produced susceptibility maps with higher subjective quality due to reduced shading artifacts. For both acquisition protocols, higher linear correlation with both - and -based measurements were observed for the data-adaptive method ( for , for ) than the standard method ( and ). For both protocols, the data-adaptive method enabled better test-retest repeatability (repeatability coefficients 0.19/0.30 ppm for the data-adaptive method, 0.38/0.47 ppm for the standard method) and reproducibility across protocols (reproducibility coefficient 0.28 vs. 0.53ppm) than the standard method. The proposed data-adaptive QSM algorithm may enable quantification of LIC with improved repeatability/reproducibility across different acquisition parameters as 3T.

The role of iron in the formation of Ediacaran 'death masks'.

The Ediacara biota are an enigmatic group of Neoproterozoic soft-bodied fossils that mark the first major radiation of complex eukaryotic and macroscopic life. These fossils are thought to have been preserved via pyritic "death masks" mediated by seafloor microbial mats, though little about the chemical constraints of this preservational pathway is known, in particular surrounding the role of bioavailable iron in death mask formation and preservational fidelity. In this study, we perform decay experiments on both diploblastic and triploblastic animals under a range of simulated sedimentary iron concentrations, in order to characterize the role of iron in the preservation of Ediacaran organisms. After 28 days of decay, we demonstrate the first convincing "death masks" produced under experimental laboratory conditions composed of iron sulfide and probable oxide veneers. Moreover, our results demonstrate that the abundance of iron in experiments is not the sole control on death mask formation, but also tissue histology and the availability of nucleation sites. This illustrates that Ediacaran preservation via microbial death masks need not be a "perfect storm" of paleoenvironmental porewater and sediment chemistry, but instead can occur under a range of conditions.

A novel colorimetric technique for estimating iron in magnetosomes of magnetotactic bacteria based on linear regression.

Magnetotactic bacteria (MTB) use iron from their habitat to create magnetosomes, a unique organelle required for magnetotaxis. Due to a lack of cost-effective assay methods for estimating iron in magnetosomes, research on MTB and iron-rich magnetosomes is limited. A systemized assay was established in this study to quantify iron in MTB using ferric citrate colorimetric estimation. With a statistically significant R2 value of 0.9935, the iron concentration range and wavelength for iron estimation were optimized using linear regression. This colorimetric approach and the inductively coupled plasma optical emission spectrometry (ICP-OES) exhibited an excellent correlation R2 value of 0.961 in the validatory correlative study of the iron concentration in the isolated magnetotactic bacterial strains. In large-scale screening studies, this less-expensive strategy could be advantageous.

Spatial Distribution and Source Identification of Water Quality Parameters of an Industrial Seaport Riverbank Area in Bangladesh

The Pasur River is a vital reservoir of surface water in the Sundarbon area in Bangladesh. Mongla seaport is located on the bank of this river. Many industries and other commercial sectors situated in this port area are discharging waste into the river without proper treatment. For this reason, geospatial analysis and mapping of water pollutant distribution were performed to assess the physicochemical and toxicological situation in the study area. We used different water quality indices such as Metal Index (MI), Comprehensive Pollution Index (CPI), and Weighted Arithmetic Water Quality Index Method (WQI) to improve the understanding of pollution distribution and processes determining the quality of river water. Multivariate statistical methods were used to evaluate loads and sources of pollutants in the Pasur River system. The results indicate that the sources of contaminants are both geogenic and anthropogenic, including untreated or poorly treated wastewater from industries and urban domestic waste discharge. The concentration range of total suspended solid (TSS), chloride, iron (Fe), and manganese (Mn) were from 363.2 to 1482.7, 108.2 to 708.93, 1.13 to 2.75, and 0.19 to 1.41 mg/L, respectively, significantly exceeding the health-based guideline of WHO and Bangladeshi standards. The high Fe and Mn contents are contributions from geogenic and anthropogenic sources such as industrial waste and construction activities. The average pH value was 8.73, higher than the WHO and Bangladeshi standard limit. WQI (ranging from 391 to 1336), CPI (6.71 to 23.1), and MI (7.23 to 23.3) were very high and greatly exceeded standard limits indicating that the Pasur River water is highly polluted. The results of this study can be used as a first reference work for developing a surface water quality monitoring system and guide decisionmakers for priorities regarding wastewater treatment.

Spectroscopy-based multi-parametric quantification in subjects with liver iron overload at 1.5T and 3T.

To evaluate the precision profile (repeatability and reproducibility) of quantitative STEAM-MRS and to determine the relationships between multiple MR biomarkers of chronic liver disease in subjects with iron overload at both 1.5 Tesla (T) and 3T. MRS data were acquired in patients with known or suspected liver iron overload. Two STEAM-MRS sequences (multi-TE and multi-TE-TR) were acquired at both 1.5T and 3T (same day), including test-retest acquisition. Each acquisition enabled estimation of R1, R2, and FWHM (each separately for water and fat); and proton density fat fraction. The test-retest repeatability and reproducibility across acquisition modes (multi-TE vs. multi-TE-TR) of the estimates were evaluated using intraclass correlation coefficients, linear regression, and Bland-Altman analyses. Multi-parametric relationships between parameters at each field strength, across field strengths, and with liver iron concentration were also evaluated using linear and nonlinear regression. Fifty-six (n = 56) subjects (10 to 73 years, 37 males/19 females) were successfully recruited. Both STEAM-MRS sequences demonstrated good-to-excellent precision (intraclass correlation coefficient ≥ 0.81) for the quantification of R1water , R2water , FWHMwater , and proton density fat fraction at both 1.5T and 3T. Additionally, several moderate (R2 = 0.50 to 0.69) to high (R2 ≥ 0.70) correlations were observed between biomarkers, across field strengths, and with liver iron concentration. Over a broad range of liver iron concentration, STEAM-MRS enables rapid and precise measurement of multiple biomarkers of chronic liver disease. By evaluating the multi-parametric relationships between biomarkers, this work may advance the comprehensive MRS-based assessment of chronic liver disease and may help establish biomarkers of chronic liver disease.

A Friendly Complexing Agent for Spectrophotometric Determination of Total Iron.

Iron, one of the most common metals in the environment, plays a fundamental role in many biological as well as biogeochemical processes, which determine its availability in different oxidation states. Its relevance in environmental and industrial chemistry, human physiology, and many other fields has made it necessary to develop and optimize analysis techniques for accurate determination. Spectrophotometric methods are the most frequently applied in the analytical determination of iron in real samples. Taking advantage of the fact that desferrioxamine B, a trihydroxamic acid used since the 1970s in chelation therapy for iron overload treatment, forms a single stable 1:1 complex with iron in whichever oxidation state it can be found, a smart spectrophotometric method for the analytical determination of iron concentration was developed. In particular, the full compliance with the Lambert-Beer law, the range of iron concentration, the influence of pH, and the interference of other metal ions have been taken into account. The proposed method was validated in terms of LoD, LoQ, linearity, precision, and trueness, and has been applied for total iron determination in natural water certified material and in biological reference materials such as control human urine and control serum.

Potentiometric Response of Solid-State Sensors Based on Ferric Phosphate for Iron(III) Determination.

A novel ion-selective electrode with membranes based on iron(III) phosphate and silver sulfide integrated into a completely new electrode body design has been developed for the determination of iron(III) cations. The best response characteristics with linear potential change were found in the iron(III) concentration range from 3.97 × 10−5 to 10−2 mol L−1. The detection limit was found to be 2.41 × 10−5 mol L−1 with a slope of −20.53 ± 0.63 and regression coefficient of 0.9925, while the quantification limit was 3.97 × 10−5 M. The potential change per concentration decade ranged from −13.59 ± 0.54 to −20.53 ± 1.56 for Electrode Body 1 (EB1) and from −17.28 ± 1.04 to −24 ± 1.87 for Electrode Body 2 (EB2), which is presented for the first time in this work. The prepared electrode has a long lifetime and the ability to detect changes in the concentration of iron cations within 20 s. Membrane M1 showed high recoveries in the determination of iron cations in iron(III) standard solutions (98.2–101.2%) as well as in two different pharmaceuticals (98.6–106.5%). This proves that this type of sensor is applicable in the determination of ferric cations in unknown samples, and the fact that all sensor parts are completely manufactured in our laboratory proves the simplicity of the method.

Method validation on iron determination by spectrophotometric method in aqueous medium

This paper deals with the validation of a method for the determination of iron in spectrophotometric method in aqueous medium. The method is based on complex formation of iron with thioglycolic acid (TGA) in alkaline medium in presence of a masking agent to produce a red purple chelate that has an absorption maximum at 535 nm wavelength. Beer’s-Lambert’s law is obeyed and linear calibration curves were obtained for the concentration range of iron from 0.1 mg/L to 30 mg/L. The reaction is found to be spontaneous in alkaline medium. The limit of detection (LOD) and limit of quantification (LOQ) for the developed method are 0.0108 and 0.0345 respectively. Effect of different parameters like molar ratio of iron to different reagents and interferences, effect of time and effect of temperature of this method of determination were studied. It is found that this method is moderately sensitive and has been successfully applied for the determination of iron (III) in different fields like ceramic materials, clay, sand, glass, stone, soil, water, and any inorganic iron containing compound or alloys. A comparison report is made for Chevron gas field waste material and Certified Reference Material (CRM) of iron, which was done by Atomic Absorption Spectrophotometer (AAS) and Ultraviolet-visible (UV-Vis) spectrophotometer and found to be comparable.

The role of iron in magnetic damping of Mg(Al,Fe)2O4 spinel ferrite thin films

We have investigated magnesium aluminum ferrite thin films with a range of iron concentrations and identified the optimal iron content to obtain high crystalline quality thin films with the low magnetic damping required for spin current-based applications. Epitaxial MgAl2−x FexO4 films with 0.8 &amp;lt; x &amp;lt; 2.0 were grown by pulsed laser deposition on single crystal MgAl2O4 substrates and were characterized structurally and magnetically. We find that the x = 1.5 composition minimizes the room-temperature magnetic damping with a typical Gilbert damping parameter of αeff=1.8×10−3. This minimized damping is governed by a competition between the more robust magnetic ordering with increased iron content, x, and the more defective structure due to larger film-substrate lattice mismatch with increased iron content. The temperature-dependent magnetization curves indicate that Tc is suppressed below room temperature for iron content x≤1.2 and eventually suppressed entirely for x = 0.8. X-ray magnetic circular dichroism results indicate that for all x the magnetic moment is dominated by Fe3+ cations distributed in a 60:40 ratio on the octahedral and tetrahedral sites, with minimal contribution from Fe2+ cations. Films with x=1.4−1.6 exhibit very strong ferromagnetic resonance and low Gilbert damping with αeff=(1.8−6)×10−3, making them ideal candidates for microwave and spintronic applications.

Relationship between the ideality factor and the iron concentration in silicon solar cells

Abstract The ideality factor value of silicon n + − p solar cells with iron contaminants has been studied by means of computer simulation. The iron concentration range of 1 0 10 − 1 0 13 cm−3, base doping level range of 1 0 15 − 1 0 17 cm−3, and temperature range of 290 − 340 K were used in the investigation. The Solar Cells Capacitance Simulator (SCAPS) was the tool used for numerical simulation of these devices. The two-diode model was used to extract the ideality factor. The following cases were considered: (i) Shockley–Read–Hall (SRH) recombination; (ii) both intrinsic recombination and SRH recombination; (iii) unpaired interstitial iron atoms; (iv) both iron–boron pairs and interstitial iron atoms. The algorithms of iron concentration evaluation in silicon solar cell by using current–voltage curve are proposed. The analytic expressions are suggested as well as calibration curves are calculated.

Insight into the interaction mechanism of iron ions with soil humic acids. The effect of the pH and chemical properties of humic acids.

The main aim of this work was to study the mechanisms of interaction between iron(II) ions and humic acids as a function of pH, iron concentration and various humic acids chemical properties, including the degree of humification, elemental composition, aromaticity and content of acidic functional groups. The results indicated that iron was bound by humic acids at pH 7 in amounts ∼2 times higher than at pH 5 (averaged capacities: 117 and 57 cmol/kg, respectively). Iron binding at pH 7 increased with increasing the total carboxylic and phenolic groups content and the degree of humification of humic acids (R-coefficients: 0.99 and 0.95, respectively). The stability of humic acid-iron complexes at pH 7 were only slightly lower than at pH 5 due to iron hydroxides formed at pH > 5 (averaged stability constants: 5.18 and 5.26, respectively). Iron coordination mode varied depending on pH: at pH 5, the bidentate (chelate) mode dominated, whereas at pH 7 the bridging mode appeared prevalent. The total amount of bound iron was much smaller than the content of the carboxylic and phenolic groups in humic acids, on average by ∼80 (pH 7) and ∼90.1% (pH 5) indicating the occurrence of steric effects in humic acid structure i.e. the reduction of the complexation capacity of free functional groups by adjacent groups occupied by iron and/or the formation of intramolecular aggregates with iron hindering the access of further metal ions. At pH 5 the complexes were soluble in the iron concentration range positively correlated to carboxylic and phenolic groups content, showing the protective nature of negatively charged functional groups on the stability of the solution. At this pH, the destabilization of the system was governed by the neutralization of humic acid charged structures by metal cations and the compression of the double electric layer. At pH 7 the stability of the humic acid-iron solution was largely determined by the form of iron, mainly by the precipitation of metal hydroxides acting as a flocculant destabilizing the solution by co-precipitation of humic acid-iron complexes.

Regulation of Iron Uptake by Fine-Tuning the Iron Responsiveness of the Iron Sensor Fur.

Iron is one of most abundant environmental metal ions but is highly limited in organisms. It is an important metal ion as it facilitates various biological processes, including catalysis of metabolic enzymes and DNA biogenesis. In bacteria, the ferric uptake regulator (Fur) protein controls iron uptake by regulating genes coding for iron transporters in response to iron concentration. This iron response is ascribed to Fur's intrinsic affinity for iron because its binding to iron dictates its regulatory function. However, we now report that the pathogen Salmonella achieves a proper response of Fur to changes in environmental iron concentrations via EIIANtr (a nitrogen metabolic phosphotransferase system component). We establish that EIIANtr increases expression of iron transporter-coding genes under low-iron conditions (i.e., nanomolar ranges) in a Fur-dependent manner, which promotes Salmonella growth under such conditions. EIIANtr directly hampers Fur binding to DNA, thereby inducing expression of those genes. This regulation allows Salmonella to express Fur-regulated genes under low-iron conditions. Our findings reveal a potentially widespread control mechanism of bacterial iron uptake systems operating in response to iron availability.IMPORTANCE Iron is a fundamental metal ion for living organisms as it facilitates various biological processes. The ferric uptake regulator (Fur) protein controls iron homeostasis in various bacterial species. It is believed that Fur's iron-dependent regulatory action is sufficient for it to function as an iron sensor. However, we now establish that the bacterial pathogen Salmonella enables Fur to properly reflect changes in surrounding iron availability by fine-tuning its responsiveness to iron. This process requires a protein that hampers Fur DNA binding at low iron concentrations. In this way, Salmonella broadens the range of iron concentrations that Fur responds to. Our findings reveal a potentially widespread control mechanism of bacterial iron homeostasis.

Basic and clinical science posters: Beta cells, islets and stem cells

Aims: Exposure to high levels of glucose and iron have been co‐related to reactive oxygen species (ROS) generation and oxidative stress in beta cell. This study aimed to test their accumulation in the beta cell and effects upon cellular oxidative dysfunction, cell viability, and insulin synthesis and secretion. Methods: MIN6 pseudoislets were exposed to a range of iron concentrations (20–100µM) at predefined glucose levels (5.5 and 11mM) in a static incubation experiment (48 and 72h). Iron storage was assessed by a ferritin immunoassay. Cellular insulin release and content were measured by an insulin immunoassay. ROS mediated cellular oxidative stress was estimated by measuring cellular lipid peroxidation (TBARS assay) and cell viability was assessed by a resazurin dye‐based assay. Results: Our results demonstrate that the presence of 11mM glucose and 100µM iron exposure at 72h exerted the most detrimental effect on the MIN6 beta cell viability (viability ≤59.5% and ≤54% respectively, n = 4). This observation is consistent with the data from cellular iron uptake analysis, which revealed the highest iron accumulation (ferritin = 325 ± 2.62ng/µg protein, n = 4) and TBARS assay that demonstrated the highest levels of lipid peroxidation (323.9 ± 1.57nmol/µg protein, n = 4) under these conditions. Insulin secretion and content were progressively decreased corresponding to chronic incubation time (27.5 ± 0.4and 38.4 ± 2.83ng/mg protein, respectively, p < 0.05, n = 4). Summary: Our data suggest that exposure to high iron and glucose concentrations results in cellular damage and may initiate secretory dysfunction in the beta cell.

Iron Transport from Ferrous Bisglycinate and Ferrous Sulfate in DMT1-Knockout Human Intestinal Caco-2 Cells.

This experiment was conducted to investigate the transport characteristics of iron from ferrous bisglycinate (Fe-Gly) in intestinal cells. The divalent metal transporter 1 (DMT1)-knockout Caco-2 cell line was developed by Crispr-Cas9, and then the cells were treated with ferrous sulfate (FeSO4) or Fe-Gly to observe the labile iron pool and determine their iron transport. The results showed that the intracellular labile iron increased significantly with Fe-Gly or FeSO4 treatment, and this phenomenon was evident over a wide range of time and iron concentrations in the wild-type cells, whereas in the knockout cells it increased only after processing with high concentrations of iron for a long time (p < 0.05). DMT1-knockout suppressed the synthesis of ferritin and inhibited the response of iron regulatory protein 1 (IRP-1) and IRP-2 to these two iron sources. The expression of peptide transporter 1 (PepT1) was not altered by knockout or iron treatment. Interestingly, the expression of zinc-regulated transporter (ZRT) and iron-regulated transporter (IRT)-like protein 14 (Zip14) was elevated significantly by knockout and iron treatment in wild-type cells (p < 0.05). These results indicated that iron from Fe-Gly was probably mainly transported into enterocytes via DMT1 like FeSO4; Zip14 may play a certain role in the intestinal iron transport.