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The reduction of ferric iron (Fe(III)) to ferrous iron (Fe(II)) by dissimilatory iron-reducing bacteria is widespread in anaerobic environments. The oxidation of Fe(II) in aerobic environments has been found to produce hydroxyl radicals (

Pathogenic bacteria scavenge ferric iron from the host for survival and proliferation using small-molecular chelators, siderophores. Here, we introduce and assess the gallium(III) complex of ciprofloxacin-functionalized desferrichrome (D2) as a potential therapeutic for bacterial infection using an in vitro assay and radiochemical, tracer-based approach. Ga-D2 exhibits a minimum inhibitory concentration of 0.23 μM in Escherichia coli, in line with the parent fluoroquinolone antibiotic. Competitive and mutant strain assays show that Ga-D2 relies on FhuA-mediated transport for internalization. Ga-D2 is potent against Pseudomonas aeruginosa (3.8 μM), Staphylococcus aureus (0.94 μM), and Klebsiella pneumoniae (12.5 μM), while Fe-D2 is inactive in these strains. Radiochemical experiments with E. coli reveal that (67)Ga-D2 is taken up more efficiently than (67)Ga-citrate. In naive mice, (67)Ga-D2 clears renally and is excreted 13% intact in the urine. These pharmacokinetic and bacterial growth inhibitory properties qualify Ga-D2 for future investigations as a diagnosis and treatment tool for infection.

Streptomyces are a distinguished group of gram-positive bacteria mostly acknowledged for their immense contribution to life-saving drugs and lines of compounds with diverse bioactivities. To date, there remains limited studies on Streptomyces with biological activities residing in underexplored ecosystems such as the mangrove forests. For this purpose, the present work aimed at investigating the biological activity of Streptomyces sp. MUSC 11 collected from soil sample in mangrove forests, situated in the State of Pahang, Peninsular of Malaysia. The cultured strain resembled phenotypic and genotypic traits of genus Streptomyces. Investigations of the methanolic extract from Streptomyces sp. MUSC 11 revealed antioxidant activities in form of scavenging free radicals ABTS, DPPH, chelating iron and reducing ferric iron. Besides the antioxidant tests, antioxidant results corresponded well to the presence of phenolic content. In summary, Streptomyces derived from extreme and understudied ecosystem such as the mangrove forests are potential sources of biologically active and therapeutically useful compounds.

The cumulative effects of periodic redox cycling on the mobility of As, Fe, and S from alluvial sediment to groundwater were investigated in bioreactor experiments. Two particular sediments from the alluvial floodplain of the Mekong Delta River were investigated: Matrix A (14 m deep) had a higher pyrite concentration than matrix B (7 m deep) sediments. Gypsum was present in matrix B but absent in matrix A. In the reactors, the sediment suspensions were supplemented with As(III) and SO42-, and were subjected to three full-redox cycles entailing phases of nitrogen/CO2, compressed air sparging, and cellobiose addition. Major differences in As concentration and speciation were observed upon redox cycling. Evidences support the fact that initial sediment composition is the main factor controlling arsenic release and its speciation during the redox cycles. Indeed, a high pyrite content associated with a low SO42- content resulted in an increase in dissolved As concentrations, mainly in the form of As(III), after anoxic half-cycles; whereas a decrease in As concentrations mainly in the form of As(V), was instead observed after oxic half-cycles. In addition, oxic conditions were found to be responsible for pyrite and arsenian pyrite oxidation, increasing the As pool available for mobilization. The same processes seem to occur in sediment with the presence of gypsum, but, in this case, dissolved As were sequestered by biotic or abiotic redox reactions occurring in the Fe-S system, and by specific physico-chemical condition (e.g. pH). The contrasting results obtained for two sediments sampled from the same core show that many complexes and entangled factors are at work, and further refinement is needed to explain the spatial and temporal variability of As release to groundwater of the Mekong River Delta (Vietnam). (C) 2019, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V.

Iron is an essential nutrient needed for physiological functions, particularly during the developmental period of the early childhood of at-risk populations. The purpose of this study was to investigate, in an experimental colitis, the consequences of daily oral iron ingestion in the early period on the inflammatory response, the spleen T helper (Th) profiles and the associated molecular mechanisms. Juvenile mice orally received microencapsulated ferric iron or water for 6 weeks. On adult mice, we induced a sham or experimental trinitrobenzene sulfonic acid (TNBS) moderate colitis during the last week of the experiment before sacrificing the animals 7 days later. The severity of the gut inflammation was assessed by macroscopic damage scores (MDS) and the myeloperoxidase activity (MPO). Th profiles were evaluated by the examination of the splenic gene expression of key transcription factors of the Th differentiation (Tbet, Gata3, Foxp3 and ROR&gamma, ) and the methylation of their respective promoter. While TNBS-induced colitis was associated with a change of the Th profile (notably an increase in the Tbet/Gata3 ratio in the spleen), the colitis-inhibition induced by ferric iron was associated with a limitation of the splenic Th profiles perturbation. The inhibition of the splenic Tbet gene overexpression was associated with an inhibition of promoter hypomethylation. In summary, mice treated by long-term oral ferric iron in the early period of life exhibited an inhibition of colitis associated with the inhibition of the splenic Tbet promoter hypomethylation and gene overexpression.

espanolEl objetivo de esta investigacion fue obtener snacks de cidra Sechium edule (Jacq.) Sw. liofilizados utilizando la tecnica de impregnacion a vacio para la incorporacion de pulpa de lulo, inulina y calcio con el fin de potenciar sus caracteristicas funcionales. La cidra se lavo, pelo y troceo en cilindros. Se elaboraron cinco snacks a partir de los cilindros de cidra, impregnandolos a vacio con los siguientes componentes: pulpa de lulo (C1), pulpa de lulo-inulina (C2), pulpa de lulo-CaCl2 (C3) y pulpa de lulo-CaCl2-inulina (C4). Se tomaron como control, cilindros de cidra sin impregnar (C0). Se evaluo el contenido de compuestos fenolicos totales usando el metodo colorimetrico de Folin-Ciocalteu y la capacidad antioxidante por el metodo de reduccion de hierro ferrico. Se registraron diferencias significativas en el contenido de compuestos fenolicos de los snacks impregnados con los diferentes compuestos, evidenciandose un mayor contenido en los snacks C1 y C2 y una mayor actividad antioxidante en el snack C4. Se observo que la matriz de cidra en cilindros permite la incorporacion de compuestos bioactivos incrementando sus caracteristicas funcionales. La adicion de pulpa de lulo e inulina aumentaron la actividad antioxidante de los snacks. EnglishThe objective of this research was to obtain cidra snacks (Sechium edule (Jacq.) Sw.) lyophilized using the technique of vacuum impregnation for the incorporation of pulp of lulo, inulin and calcium in order to enhance their functional characteristics. The cidra was washed, peeled and cut into cylinders. Five snacks were made from the cidra cylinders, impregnated in vacuum with the following components: pulp of lulo (C1), pulp of naranjilla-inulina (C2), pulp of naranjilla-CaCl2 (C3) and pulp of naranjilla-CaCl2-inulin (C4); were taken as control, cylinders of citron without impregnated (C0). The content of total phenolic compounds was evaluated using the Folin-Ciocalteu colorimetric method and the antioxidant capacity by the ferric iron reduction method. Significant differences were registered in the content of phenolic compounds of the snacks impregnated with the different compounds, evidencing a higher content in the C1 y C2 snacks and a greater antioxidant activity in the C4 snack. It was observed that the cidra matrix in cylinders allows the incorporation of bioactive compounds increasing their functional characteristics. The addition of naranjilla pulp and inulin increased the antioxidant activity of the snack.

In modern conditions of electronic warfare, effective protection of information and control complexes of aircraft (AC) from the destructive effects of external interference is impossible without the use of innovative solutions in the field of creating new composite materials (CM) with radio-absorbing properties. This scientific area is inextricably linked with the issues of predicting the properties of these materials. A wide variety of design solutions to protect aircraft “electronics”, as well as a wide range of electromagnetic and mechanical effects, require the creation of functional materials for specific operating conditions. Thus, the developers of functional materials must have an effective tool to predict the properties of the CM being created. Solutions can be based on mathematical models that allow predicting the properties of CM and subsequently optimizing their composition. The article discusses the identification and verification of mathematical models of the mechanical characteristics of CMs based on BASF polyurethane with the addition of both untreated and processed ferric iron oxide as a filler, with subsequent optimization of the characteristics and determination of the corresponding CM composition with radio-absorbing properties. Experimental studies have been carried out, which confirm the adequacy of the developed mathematical models.

Since the process of anaerobic ammonium oxidation (anammox) coupled with ferric iron reduction (termed Feammox) was discovered, it has been observed in various natural environments. However, besides the vertical distribution of Feammox in paddy soils, its differences and relationships with traditional nitrogen loss processes, including denitrification and anammox, remain unclear. Here, we studied the distribution of nitrogen loss pathways in different layers (0–50 cm) of paddy soil in southeastern China using 15N isotope tracer technology and molecular analysis. Our study showed that denitrification had a rate of 2.19 ± 0.39 mg N·kg−1·d−1, which was the highest activity in the surface layer (0–10 cm). The activities of anammox and Feammox reached peak values in the 10–20 cm (1.13 ± 0.16 mg N·kg−1·d−1) and 20–30 cm (0.23 ± 0.02 mg N·kg−1·d−1) soil layer, respectively. The nitrogen loss in the surface layer was more serious than that in the deep layer under paddy cultivation. In this study, denitrification was the main nitrogen loss pathway in the surface soil, but Feammox became an important nitrogen loss pathway (up to 26.1%) in the 20–40 cm depth. Overall, our research could improve and perfect the nitrogen cycle pathways in paddy soil.

A major problem of oral iron supplementation efficacy in children is its tolerability and compliance. We aimed to determine the safety and efficacy of a novel food supplement >Your< Iron Syrup in the replenishment of iron stores and improvement of hematological parameters in iron-deficient children aged nine months to six years. We randomized 94 healthy children with iron deficiency in a ratio of 3:1 to either receive >Your< Iron Syrup or placebo. A 12-week supplementation with >Your< Iron Syrup resulted in a significant increase in ferritin and hemoglobin levels as compared to placebo (p = 0.04 and p = 0.02). Adverse events were reported with similar frequencies across both study arms. >Your< Iron Syrup represents an effective, well-tolerated, and safe option for the management of nutritional iron deficiency in children.

Iron is a ubiquitous element with a rich (i.e., complex) chemical behavior. It possesses three oxidation states, metallic iron (Fe), ferrous iron (Fe2+) and ferric iron (Fe3+). The distribution of these oxidation states is markedly stratified in the Earth.

Introduction: Iron cycle is one of the most important biogeochemical processes which affect the availability of iron in soils. Ferric iron oxides are the most abundant forms of iron in soils and sediments. Ferric iron is highly insoluble at circumneutral pH. Present investigations have shown that the structural ferric iron bound in clay minerals is reduced by some microorganisms. Anaerobic bacteria reduce ferric iron which bound to soil clay minerals under anaerobic conditions. They have the ability to use ferric iron as a terminal electron acceptor. Many studies presented that dissimilatory iron reducing bacteria (DIRB) mediate the transfer of electrons from small organic molecules like acetate and glucose to various humic materials (electron shuttles) which then pass electrons abiotically to ferric iron oxyhydroxide and phyllosilicate minerals. Electron shuttles like AQDS, a tricyclic quinone, increase the rate of iron reduction by iron reducing bacteria on sites of iron oxides and oxyhydroxides. By increasing the rate of bioreduction of ferric iron, the solubility and availability of iron enhanced meaningfully. Royer et al. (2002) showed that bioreduction of hematite (common iron mineral in soils) increased more than three times in the presence of AQDS and Shewanella putrefaciens comparedto control treatments. Previous works have mostly used synthetic minerals as electron acceptor in bioreduction process. Furthermore, the effect of quinones as electron acceptor for microorganisms were studied with poorly crystalline ferric iron oxides . The main objective of this study was to study the effect of AQS, humic acid and fulvic acid (as electron shuttle) and Shewanella sp. and Pseudomonas aeruginosa, on bioreduction of native ferric iron in two acidic and calcareous soils. Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in vitro condition. The soil samples collected from locations in Mashhad and Guilan cities, Iran, in 2015. The soil samples were air dried in a glasshouse and later subjected to general analysis. Some part of the soil samples were kept at 4 oC as fresh soil samples for bioreduction assay. In that part of experiment, all soil samples were treated with glucose (10 mM) as electron donor. Native ferric iron considered as electron acceptor. Then soil samples were treated with AQS, humic acid and fulvic acid (as electron shuttles) and inoculated with bacterial cells (Shewanella sp. and P. aeruginosa) and they were incubated for 30 days in an incubator at 30 and 37 oC according to the optimum temperature for bacteria in an anaerobic condition. At the end of incubation time, ferrous and acid extractable iron were determined with Ferrozine assay by spectrophotometer in 562 nm (8, 25). Results and Discussion: Results showed that the AQS had a noticeable effect on ferrous iron concentrations in both acidic and calcareous soils. In these cases ferrous iron concentrations were 8 and 15.7 times higher compared to initial concentration in acidic and calcareous soils, respectively. The Shewanella sp. intensified ferrous iron concentration 7.2 and 16.3 fold in acidic and calcareous soils, respectively but P. aeruginosa increased it 5.6 and 12.1 fold compared to initial concentration of ferrous iron. In acidic soil, in the presence of Shewanella sp. and AQS, ferrous and acid extractable iron concentrations were 1.45 and 4.50 mg g-1, respectively. Results showed that 11.7 fold enhancements occur in the presence of Shewanella sp. and AQS compared to initial (0.385 mg g-1) concentration of iron in acidic soil. When P. aeruginosa was inoculated in acidic soil in the presence of AQS, soluble ferrous iron concentration was 1.27 mg g-1. The acid extractable iron in this treatment was 2.85 mg g-1. The concentration of soluble ferrous iron in calcareous soil was 0.81 mg g-1, when AQS was added to Shewanella sp. treatments. That value was 0.54 when P. aeruginosa was added. The acid extractable iron was 3.90 mg g-1 in the presence of AQS and Shewanella sp. By adding P. aeruginosa, acid extractable iron was 2.84 mg g-1 compared to control treatments. Conclusions: Dissimilatory ferric iron reduction is a potentially important process in controlling contaminant fate. It has the potential for being particularly useful in the remediation of metals and radionuclides. Means for stimulating ferric iron reduction will be useful in enhancing bioremediation process. Results illustrated that the Shewanella sp. and P. aeruginosa were enhanced the bioreduction of ferric iron in the presence of AQS, humic acid and fulvic acid in soils. When soil samples were inoculated with Shewanella sp., and AQS was added to the soil samples (in acidic and calcareous soil samples) the concentration of ferrous iron increased intensively.

The kaolin (s.l.) in many tropical soils is distinctly different from most specimen and industrial kaolins. Crystal structure is highly disordered and crystal sizes are much smaller than for specimen and industrial kaolins. The crystal habit of soil kaolins is diverse ranging through euhedral hexagonal and anhedral platy, spheroidal and tubular. The specific surface of soil kaolins is higher than for most industrial kaolins. Consequently, cation and anion retention capacities are higher although there is no compelling evidence that the high structural disorder of soil kaolin is associated with a greater specific reactivity of the kaolin surface. A small amount of ferric iron substitutes for octahedral Al but there is generally little or no substitution of other cations. Soil kaolin commonly contains minor amounts of potassium but this is present in mica layers within, attached or associated with kaolin crystals so that potassium is not within the kaolin structure. Due to its considerable chemical reactivity soil kaolin helps provide an effective substrate to support agriculture and other land uses in the tropics.

Numerous techniques are available to determine the amount of Fe 2+ and Fe 3 + in minerals. Calculating Fe 2+ and Fe 3 + by charge-balance using electron probe microanalysis (EPMA) data is the most common method, but several studies question the usefulness and accuracy of this approach (Canil and O’Neill 1996; Dyar et al. 1993, 2012; Lalonde et al. 1998; Li et al. 2005; McGuire et al. 1989; Schingaro et al. 2016; Schmid et al. 2003; Sobolev et al. 2011). We compile and compare data for natural garnets that have been analyzed by both EPMA and Mossbauer spectroscopy. Comparison of Fe 3 + / ∑Fe determined by charge-balance vs. Mossbauer spectroscopy shows an approximate 1:1 correlation. The EPMA data set of Dyar et al. (2012) is reexamined and it is shown that disagreement between EPMA and Mossbauer for their data is not nearly as bad as reported. Data for charge-balance vs. Mossbauer spectroscopy are compared and show that the EPMA/charge-balance approach provides a suitable alternative when other methods are not practical.

The aim of the study is — to develop a strategy of prevention of hypoxic fetal abnormalities in pregnant women with congenital heart disease, heart failure and iron deficiency anemia. Materials and methods. The study included 86 pregnant women with CHD and NYHA II–III. 68 women in the third trimester of pregnancy is diagnosed anemia (group I), 18 pregnant women with CHD, NYHA II–III without anemia (II group), the control group consisted of 24 pregnant women without cardiac disease, with physiological pregnancy. All pregnant with information registration consent studied the concentration of ferritin, hemoglobin level, morphological study of the placenta. All pregnant women were assigned to iron supplements, oral iron (III) hydroxide polymaltose complex (Maltofer) when hemoglobin levels above 95 g/l and the expected delivery date more than 40 days of starting treatment. When the hemoglobin level below 95 g/l of intravenously administered iron (III) hydroxide sucrose complex (Venofer) followed by transfer to oral iron (III). Results. In groups of pregnant I and II did not have perinatal losses, births in gestation less than 28 weeks, with a score Apgar at birth of less than 4 points. Pregnant women with cyanotic heart defects and the need for early delivery in less than 37 weeks are not included in the study. Also, there is a correlation between the degree of severity of anemia in women with CHD with HF and prematurity, and the presence of IUGR child birth asphyxia able to varying degrees (respectively, r=0.8, r=0.75 and r=0.85). Conclusions. Formation of fetoplacental unit in women with CHD on a background of heart failure occurs with complications associated with the presence of tissue hypoxia, as well as the possible impact on the process of oxidative stress. The development of iron deficiency anemia in this group is an additional risk factor for placental dysfunction, which is confirmed by morphometric and morphological studies of placentas. Early prevention and prompt treatment can significantly reduce the incidence of complications and improve perinatal outcomes in this group of patients.

The observed biological differences in safety and efficacy of intravenous (IV) iron formulations are attributable to physicochemical differences. In addition to differences in carbohydrate shell, polarographic signatures due to ferric iron [Fe(III)] and ferrous iron [Fe(II)] differ among IV iron formulations. Intravenous iron contains Fe(II) and releases labile iron in the circulation. Fe(II) generates toxic free radicals and reactive oxygen species and binds to bacterial siderophores and other in vivo sequestering agents. To evaluate whether differences in Fe(II) content may account for some observed biological differences between IV iron formulations, samples from multiple lots of various IV iron formulations were dissolved in 12 M concentrated HCl to dissociate and release all iron and then diluted with water to achieve 0.1 M HCl concentration. Fe(II) was then directly measured using ferrozine reagent and ultraviolet spectroscopy at 562 nm. Total iron content was measured by adding an excess of ascorbic acid to reduce Fe(III) to Fe(II), and Fe(II) was then measured by ferrozine assay. The Fe(II) concentration as a proportion of total iron content [Fe(III) + Fe(II)] in different lots of IV iron formulations was as follows: iron gluconate, 1.4 and 1.8 %; ferumoxytol, 0.26 %; ferric carboxymaltose, 1.4 %; iron dextran, 0.8 %; and iron sucrose, 10.2, 15.5, and 11.0 % (average, 12.2 %). The average Fe(II) content in iron sucrose was, therefore, ≥7.5-fold higher than in the other IV iron formulations. Further studies are needed to investigate the relationship between Fe(II) content and increased risk of oxidative stress and infections with iron sucrose.

Zero-valent iron (ZVI) is commonly used for the in situ remediation of groundwater aquifers contaminated with trichloroethylene (TCE); however, ZVI is susceptible to passivation over time, which can significantly reduce its treatment efficiency. Recent studies have suggested that electrically-induced reduction (EIR) or "E-Redox" technology, which applies a low-level direct current (DC), can restore the reactivity of passivated ZVI in situ . In this study, a continuous-flow column reactor was used to assess the effects of low-voltage DC on the abiotic reduction of TCE in groundwater and on the performance of passivated ZVI. In experiments with partially passivated ZVI, the application of DC increased the rate and the extent of TCE reduction; both were correlated with the level of applied voltage (0–12 V). The results provide evidence that EIR may partially recover the reduction potential of passivated ZVI and shows promise as a technique to extend the longevity of zero-valent iron. Several mechanisms, including the reduction of ferric iron minerals to ferrous iron at the ZVI surface, likely results in the enhanced TCE reduction.

Summary Viscoelastic-surfactant (VES) -based acid systems have been used successfully in matrix-acidizing and acid-fracturing treatments. However, the existence of Fe(III) as a contaminant in such systems may lead to many problems because of the interactions between VES and Fe(III). Such interactions can reduce the effectiveness of VES-based acid systems and potentially lead to formation damage. In this study, two commercial VES products were used and the interactions between VES and Fe(III) were studied. Rheological properties of these two VES-based acids were examined with various concentrations of Fe(III). Energy-dispersive X-ray spectroscopy was used to identify precipitates from the reaction products. Inductively coupled plasma was applied to measure iron concentrations, and the two-phase titration method was used to determine the VES concentrations in all liquid phases of the samples. The effect of several chelating agents on the reaction of VES with Fe(III) was also examined. Experimental results indicate that the apparent viscosity of live VES-1-based acids [20 wt% hydrochloric acid (HCl) and 4 vol% VES-1] increased from approximately 2 to 126 cp at a shear rate of 100 s−1 at room temperature when the Fe(III) concentration increased from 0 to 1,400 ppm, and it started to decrease at higher Fe(III) concentrations. This is because of the electrostatic interactions between negatively charged [FeCl4]− groups and positively charged amine groups in VES in live acids. Live VES-2-based acids (20 wt% HCl and 4 vol% VES-2) showed properties similar to those of the VES-1-based acids in apparent viscosity. Both surfactants interacted with Fe(III) and precipitates, which are complexes containing iron and VES. These interactions were noted at Fe(III) concentrations greater than 5,000 ppm. On the other hand, the addition of a chelating agent [1:1 mole ratio to Fe(III)] helped to reduce the apparent viscosity of the sample, which means that the chelating agent reacted with Fe(III) and reduced the interactions between VES and Fe(III). At the same time, when the Fe(III) concentration was 6,000 ppm in VES-2-based acid, the disappearance of precipitates with the addition of chelating agents showed a reduction of the Fe(III) impact on such VES-based acid systems. Moreover, the addition of enough chelating agent [more than 1:1 mole ratio to Fe(III) amount] reduced the amount of precipitates that formed significantly when the Fe(III) concentration was very high. Adding a suitable chelating agent can minimize the impact of Fe(III) on VES-based acids.

Objective: As a pharmaceutical raw material, ferric chloride hexahydrate has been included in the British Pharmacopoeia, the European Pharmacopoeia (2008) and the United States Pharmacopoeia (2015), and there are detailed discussions on quality standards and testing methods. Ferric chloride hexahydrate has not been included in the Chinese Pharmacopoeia. This study is the part of research to establish a spectrophotometric method for the determination of ferrous iron in ferric chloride hexahydrate. In this study, the two methods were discussed in detail, and the spectrophotometric method for detecting the content of ferrous iron in ferric chloride hexahydrate was proposed. Methods: The detection method on ferrous iron in ferric chloride hexahydrate among European pharmacopoeia, United States pharmacopoeia and Chemical Reagent Ferric Chloride Hexahydrate (HG/T3474-2014) of China's Chemical Industry were compared. The last two methods were not easy to operation. On the basis of the European pharmacopoeia, a method was proposed that after Fe3+ were screened with H3PO4, Fe2+ was measured by spectrophotometry, and the method was verified by experiments. Results and Conclusion: The spectrophotometry method is easy to operate and has good reproducibility. The content of ferrous iron can be calculated semi-quantitatively by masking ferric iron with H3PO4 and spectrophotometric determination of ferrous ion content. Therefore, the method established in this study can more clearly detect whether the ferrous content in ferric chloride hexahydrate is up to standard.

A variety of Magnetic Resonance Imaging (MRI) techniques are known to be sensitive to brain iron content. In principle, iron sensitive MRI techniques are based on local magnetic field variations caused by iron particles in tissue. The purpose of this study was to investigate the sensitivity of MR relaxation and magnetization transfer parameters to changes in iron oxidation state compared to changes in iron concentration. Therefore, quantitative MRI parameters including R1, R2, R2∗, quantitative susceptibility maps (QSM) and magnetization transfer ratio (MTR) of post mortem human brain tissue were acquired prior and after chemical iron reduction to change the iron oxidation state and chemical iron extraction to decrease the total iron concentration. All assessed parameters were shown to be sensitive to changes in iron concentration whereas only R2, R2∗ and QSM were also sensitive to changes in iron oxidation state. Mass spectrometry confirmed that iron accumulated in the extraction solution but not in the reduction solution. R2∗ and QSM are often used as markers for iron content. Changes in these parameters do not necessarily reflect variations in iron content but may also be a result of changes in the iron’s oxygenation state from ferric towards more ferrous iron or vice versa.

Low-level saltwater intrusion and ferric iron (Fe(III)) loading are predicted for many mineral tidal freshwater ecosystems under sea-level rise. To assess their effects on the carbon mineralization processes, in-situ experiments were conducted with four treatments: Fe(III) amendment, saltwater addition, saltwater addition plus Fe(III) amendment, and a control. Soil and porewater samples (0–30 cm) were collected to assess geochemical properties and soil incubation on Days 460 and 580 after the start of the experiment. Saltwater addition increased the salinity from freshwater (0.1 mg·g−1) to oligohaline (

The thiourea (TU) leaching of gold from refractory ores can be considered an alternative to cyanidation. However, the high reagent consumption causes an increase in cost, which seriously limits its use. In order to effectively reduce the TU consumption, it is necessary to analyze the influencing parameters of gold recovery and TU consumption and apply them to the prediction of the TU leaching process. This paper investigated six potential influencing parameters and used grey relational analysis (GRA) to analyze the relational degree between each parameter and gold recovery and TU consumption. Then, the artificial neural network (ANN) model was established to simultaneously predict the gold recovery and TU consumption in the TU gold leaching process. The results of the GRA indicated that the leaching time, initial pH, temperature, TU dosage, stirring speed, and ferric iron concentration were all well related to the gold recovery and TU consumption. Therefore, the incorporation of these parameters can significantly improve the ANN model validation. The predictive results noted that the prediction accuracy of gold recovery varied from 94.46% to 98.06%, and the TU consumption varied from 95.15% to 99.20%. Thus, the predicted values corresponded closely to the experimental results, which suggested that the ANN model can accurately reflect the relationship between the operational conditions and the gold recovery and TU consumption. This prediction method can be used as an auxiliary decision-making tool in the TU gold leaching process, and it has broad engineering application prospects in engineering.

Turmeric is increasingly studied as an anti-inflammatory and anti-neoplastic agent. It binds to ferric iron in the gut and causes iron deficiency in mice. We report here a possible case of iron deficiency anemia in a human taking turmeric. A 66-year-old physician treated himself for an osteoarthritis flare after steroids with six turmeric extract capsules (538 mg) daily, to help with inflammation. During this time, his hemoglobin never rose above 12 and his iron and ferritin levels were consistent with iron deficiency. Upper and lower endoscopy and Hemoccult™ studies were negative. Two weeks after stopping the turmeric and continuing his usual iron supplement, his hemoglobin had returned to normal, with normalizing iron studies. Turmeric was associated with significant iron deficiency anemia, consistent with the binding of available iron in the gut and the prevention of absorption. This resolved after the turmeric was stopped, consistent with animal studies. This may be the first case of documented iron deficiency anemia in people due to turmeric supplements. Given the widespread use of turmeric and curcumin supplements across many illnesses, further attention is warranted.

More than 500 siderophores that bind ferric iron have been characterized and grouped by type based on their chemical structure. The chrome azurol S (CAS) assay is a universal colorimetric method that detects siderophores independent of their structure. In this assay, siderophores scavenge iron from an Fe-CAS-hexadecyltrimethylammonium bromide complex, and subsequent release of the CAS dye results in a color change from blue to orange. Solution-based experiments with CAS result in a quantitative measure of siderophore production, while an observable color change on CAS agar plates can be performed for qualitative detection of siderophores. Cross-feeding assays are another useful method to detect and characterize siderophores produced by bacteria. Under iron-limiting conditions, cross-feeding assays test the ability of an indicator strain to grow when supplied with a specific siderophore (from a test strain) to which it has a cognate receptor required for import into the cell. The cross-feeding assay can be tested with a variety of wild-type strains, siderophore biosynthesis mutants, and siderophore receptor mutants.

Recent studies have revealed that Earth's deep mantle may have a wider range of oxygen fugacities than previously thought. Such a large heterogeneity might be caused by material subducted into the deep mantle. However, high-pressure phase relations are poorly known in systems including Fe3+ at the top of the lower mantle, where the subducted slab may be stagnant. We therefore conducted high-pressure and high-temperature experiments using a multi-anvil apparatus to study the phase relations in a Fe3+-bearing system at 26 GPa and 1573–2073 K, at conditions prevailing at the top of the lower mantle. At temperatures below 1923 K, MgSiO3-rich bridgmanite, an Fe3+-rich oxide phase, and SiO2 coexist in the recovered sample. Quenched partial melt was observed above 1973 K, which is significantly lower than the solidus temperature of an equivalent Fe3+-free bulk composition. The partial melt obtained from the Fe3+-rich bulk composition has a higher iron content than coexisting bridgmanite, similar to the Fe2+-dominant system. The results suggest that strong mantle oxygen fugacity anomalies might alter the subsolidus and melting phase relations under lower mantle conditions. We conclude that (1) a small amount of melt may be generated from an Al-depleted region of a stagnant slab, such as subducted former banded-iron-formation, and (2) Fe3+ is not transported into the deep part of the lower mantle because of its incompatibility during melting.

During transport of wastewater in force mains, sulphide and possibly methane formation take place due to prokaryotic activity. Sulphide has several detrimental effects and addition of ferrous or ferric iron for abatement by precipitation is commonly applied. Precipitation stoichiometry and efficiency of this process have been investigated in detail. However, it is largely unknown how ferrous and ferric iron influence prokaryotic populations of sewer biofilms. The microbiomes of iron-treated force main biofilms were, together with an untreated control, examined by sequencing of the 16S rDNA V3+ V4 regions. Differences in distribution and abundance of several bacterial and archaeal genera were observed, indicating that treatment with ferrous and ferric iron for sulphide abatement differentially changed sewer force main microbiomes. Furthermore, differences at the functional level (KEGG orthologs, KOs) indicate that ferrous and ferric iron treatment possibly can decrease methane formation, whereas functions related to dissimilatory sulphate reduction seemed unaffected.

Various organic contaminants accumulated in the environment pose great threat to ecosystems and human health. Sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted increasing attention for the removal of these contaminants in recent years. Iron species, including ferrous and ferric iron, zero-valent iron, iron oxides and oxyhydroxides, iron sulfides and various supported iron catalysts, are known to be effective in activating persulfate (PS) or peroxymonosulfate (PMS) to generate sulfate radicals. This review is dedicated to summarize the up-to-date research progresses of iron-mediated activation of PS and PMS mediated by these iron-based species in both homogeneous and heterogeneous ways. The activators are categorized based on their chemistry, and the up-to-date knowledge regarding the activation mechanisms are summarized and discussed. Then, a summary of frequently-used synthesis methods of heterogeneous iron catalysts is presented. In addition, the effects of anions, solution pH, dissolved oxygen, and external energy on the activation processes are discussed. Finally, future research perspectives on the iron-based PS/PMS activation method are proposed and how to further improve such a technology for practical application are also discussed.

Metals removal from industrial process residues is essential to alleviate the potential threat to environment and avoid the resource waste. Because of very low concentration of metals and complexity of residues, conventional pyrometallurgical and hydrometallurgical routes suffer high cost and uncompleted removal. Here acid catalysis coupling bioleaching strategy was proposed for cost-efficient cleaning of metals from waste resin powder by applying double stress adapted consortium. The results showed that low pH bioleaching significantly improved the metals release, near 100% metals was leached out and no impurities of Fe(III)-precipitates was present in bioleached residue at pulp density of 10% and pH 0.7, which indicated the positive effects of acid in bioleaching of waste resin powder. Economic analysis exhibited that more profits of 33.7 $/t and 56.2 $/t residue were obtained respectively from metals recovery in case of pH 0.7 bioleaching compared with bioleaching at pH 1.5 and acid leaching at pH 0.7. Further stirring bioleaching and static leaching showed similar metals extraction rate under high pulp density conditions and TCLP tests indicated all bioleached residues could be reused as nonhazardous materials safely. However, static bioleaching showed higher ferric iron regeneration capacity and more stable community composition. These findings demonstrated that static low pH bioleaching might be more feasible for treatment of solid waste in full-scale applications from a technological and economical perspective.

The increase of waste from electric and electronic equipment has pushed the research towards the development of high sustainability treatments for their exploitation. The end-of-life printed circuit boards (PCBs) represent one of the most significant waste in this class. The interest for these scraps is due to the high Cu and Zn content, with concentrations around 25% and 2% respectively, combined with further precious metals (e.g. Au, Ag, Pd). Currently, the most common approaches developed for PCBs recycling include pyrometallurgical and hydrometallurgical treatments. On the other hand, biohydrometallurgical strategies are gaining increasing prominence, for the possibility to decrease both the environmental and the economic costs. Nevertheless, these techniques show the main limit due to the possibility to treat low quantities of waste, which makes unsustainable the further scale-up. To overcome this criticality, the present paper introduces an innovative bioleaching process carried out by Acidithiobacillus ferrooxidans (At. ferrooxidans) and Leptospirillum ferrooxidans (L. ferrooxidans). The developed technology allows to reach high PCB concentration, up to 5% (w/v), thanks to a high efficiency two-step design, able to reduce the metal toxicity on the bacteria metabolism. The treatment uses the ferric iron generated by bacterial oxidation, as oxidant, to leach Cu and Zn from PCBs. The possibility to overcome the solid concentration criticality is combined with high yield of 94% and 70% for Cu and Zn, respectively. The best selected conditions involve the At. ferrooxidans bacteria use at: 30 °C, solid concentration of 5% (w/v), 10 g/L of Fe2+, time of treatment 9 days. The experimental results are further enhanced by the carbon footprint assessment which proved the environmental advantage, compared to both the reference chemical treatment through ferric iron and literature processes (hydrometallurgical and bioleaching approaches). The analysis explained as the PCBs concentration in the solution allows to decrease the bioreactor size with the consequent reduction of energy and raw material demand. This benefit can be translated into a 4 times reduction of the CO2-eq./kg treated PCB emissions, compared to the best bioleaching processes, reported in the literature.