Search

Parkinson's disease (PD) is a progressive movement disorder associated with brain iron (Fe) accumulation and free radicals. Brown rice (BR) is antioxidant-rich and has been shown to ameliorate oxidative stress-induced damage. The aim of this study was to investigate the effects of BR compared to white rice (WR) on Fe-induced PD in a fruit fly model. Three-day-old male adult flies were divided into two groups: one on a normal diet and the other on Fe-diet (1 mmol/L) for 10 days to induce PD. After 10 days, the Fe-fed flies were redistributed into four groups: one on normal diet (Fe group), while the others were treated with BR (Fe + BR group), WR (Fe + WR group), or L-3,4-dihydroxyphenylalanine (L-dopa) (Fe + L-dopa group) for 5 days. Similarly, the flies initially on a normal diet were separated into four groups: one on normal diet (Control group), while the others were treated with BR (BR group), WR (WR group), or L-dopa (L-dopa group) for 5 days. Finally, Fe levels, dopamine, malonaldehyde (MDA), and antioxidant enzymes were measured, and the mRNA levels of antioxidant and Fe metabolism genes were assessed. BR significantly improved motor and cognitive functions, decreased fly head MDA and Fe levels, and increased antioxidant enzyme levels in comparison to the Fe and WR groups. Similarly, BR upregulated the mRNA levels of antioxidant genes: catalase, GPx, Nrf2, and DJ-1. The results suggest that BR could potentially reduce morbidities associated with PD possibly due to its bioactive compounds compared to WR. [ABSTRACT FROM AUTHOR]

The involvement of the immune oxidative stress response in the pathophysiology and pathogenesis of allergic asthma is well documented. However, reports on the role of iron homeostasis in allergic asthma is scarce. Therefore, this study aims to identify iron-related genes and proteins in mouse models of allergic asthma. Related articles were identified from SCOPUS and Web of Science databases. The article search was limited to publications in English, within a 10-year period (2014 – 2023, up to 16 August 2023) and original/research papers. All identified articles were screened for eligibility using the inclusion and exclusion criteria. All eligible articles were quality appraised prior to data extraction. Five studies were selected for data extraction. Based on the extracted data, three themes and seven subthemes related to iron homeostasis were identified. The type of samples and analytical methods used were also identified. In conclusion, our study elucidates that iron-related proteins are regulated in animal models of allergic asthma. However, the currently available data do not allow us to conclude whether the disease model resulted in iron accumulation or depletion. Therefore, further studies with other related markers should be conducted. [ABSTRACT FROM AUTHOR]

Hydrous Fe3+‐bearing bridgmanite (Bdg) is potentially a critical water host in the lowermost mantle. The spin transition behaviors of such materials are pivotal for understanding geophysical heterogeneity in the deep Earth but are poorly understood. Here, we investigated the spin transition and related geophysical properties of Fe3+ with associated H defects [Fe3+‐H] at high P‐T conditions using first‐principles simulations. Our calculations predict that the presence of hydrogen reduces the onset pressure of the spin transition of Fe3+ in Bdg, leading to higher fractions of low spin Fe3+. Along standard geotherms, spin transition is predicted to remain incomplete even at the core‐mantle boundary (CMB), and lateral temperature variations would significantly affect the proportions of high and low spin Fe and related properties like elasticity. The thermoelastic property of hydrous Fe3+‐bearing bridgmanite exhibit stronger softening anomalies at the lower mantle conditions compared to dry system, which potentially enhancing the seismic detectability of the hydrous Bdg in the deep earth. Density profile of hydrous Fe3+‐bearing bridgmanite indicates that the [Fe3+‐H] defect modestly increases the system's density, but much less than that caused by incorporating an equivalent amount of iron alone. This is crucial for understanding regions like Large Low Shear Velocity Provinces (LLSVPs), which exhibits large velocity drops but only minor density changes. The co‐adsorption of Fe and H allows for the introduction of Fe to induce velocity drops without the concomitant sharp increase in density, as pure iron would, thus enabling Fe‐H enrichment as a potential source of LLSVPs. Plain Language Summary: Ferric iron (Fe3+)‐bearing bridgmanite is the major mineral in the Earth's lower mantle and a crucial potential host for water, a vital volatile component within Earth's interior. However, the change on the electronic configuration of Fe3+, so called spin state transition in hydrous bridgmanite in lower mantle remains poorly understood. In this work, we calculated the spin transition of Fe3+ and related geophysical properties in hydrous Fe3+‐bearing bridgmanite. We found that water promotes the Fe3+ spin transition and that this transition is present over most of range of the lower mantle. We observed that the distinction in thermoelastic properties arise between hydrous and dry Fe3+‐bearing bridgmanite, potentially providing a way to distinguish between dry and hydrous bridgmanite case in the deep Earth. Finally, we found that the [Fe3+‐H] defect slightly increase the density of bridgmanite, but far less than the addition of pure iron would. This finding helps to explain the unique characteristics of Large Low Shear Velocity Provinces (LLSVPs), which show large velocity reductions but minor density changes. Therefore, [Fe3+‐H] defects could as a promising explanation for the source of LLSVPs. Key Points: Hydrogen shifts the onset pressure of Fe3+ spin transition in bridgmanite to shallower depths in the lower mantleHydrous Fe3+‐bearing bridgmanite exhibit stronger softening anomalies on elasticity compared to H‐free case at lower mantle conditionHydrogen provides a mechanism to incorporate seismic‐softening iron into bridgmanite without geophysically implausible density changes [ABSTRACT FROM AUTHOR]

In this study, 3,4-diaminobenzoic acid (DABA) was introduced into the porphyrin metal–organic framework (PCN-224) for the first time to prepare a ratiometric fluorescent probe (PCN-224-DABA) to quantitatively detect ferric iron (Fe(III)) and selenium (IV) (Se(IV)). The fluorescence attributed to the DABA of PCN-224-DABA at 345 nm can be selectively quenched by Fe(III) and Se(IV), but the fluorescence emission peak attributed to tetrakis (4-carboxyphenyl) porphyrin (TCPP) at 475 nm will not be disturbed. Therefore, the ratio of I345nm/I475nm with an excitation wavelength of 270 nm can be designed to determine Fe(III) and Se(IV). After the experimental parameters were systematically optimized, the developed method shows good selectivity and interference resistance for Fe(III) and Se(IV) detection, and has good linearity in the ranges of 0.01–4 μM and 0.01–15 μM for Fe(III) and Se(IV) with a limit of detection of 0.045 μM and 0.804 μM, respectively. Furthermore, the quenching pattern was investigated through the Stern–Volmer equation, and the results suggest that both Se(IV) and Fe(III) quenched on PCN-224-DABA can be attributed to the dynamic quenching. Finally, the constructed ratiometric fluorescent probe was applied in the spiked detection of lake water samples, which shows good applicability in real sample analysis. Moreover, the Fe(III) and Se(IV) contents in spinach and selenium-enriched rice were determined, respectively. [ABSTRACT FROM AUTHOR]

The valence state of Fe plays a vital role in setting and recording the oxidation state of magmas, commonly expressed in terms of oxygen fugacity ( f O 2 ). However, our knowledge of how and why f O 2 varies within and between magmatic systems remains patchy because of diverse challenges associated with estimating the valence state of Fe in glasses and minerals routinely. Here we investigate Fe valence systematics in magmatic clinopyroxene crystals from ocean island basalts (OIBs) erupted in Iceland and the Azores to explore whether they record information about magma Fe 3 + contents and magmatic f O 2 conditions. Although many studies assume that all Fe in augitic clinopyroxene crystals from OIBs occurs as Fe 2 + , we find that up to half of the total Fe present can occur as Fe 3 + , with crystals from alkali systems typically containing more Fe 3 + than those from tholeiitic systems. Thus, Fe 3 + is a major if under-appreciated constituent of augitic clinopyroxene crystals erupted from ocean island volcanoes. Most Fe 3 + in these crystals is hosted within esseneite component (CaFe 3 + AlSiO 6 ), though some may be hosted in aegirine component (NaFe 3 + Si 2 O 6 ) in crystals from alkali systems. Observations from samples containing quenched matrix glasses suggest that the incorporation of Fe 3 + is related to the abundance of tetrahedrally coordinated Al ( IV Al), implying some steric constraints over Fe 3 + partitioning between clinopyroxene and liquid (i.e., D Fe 2 O 3 cpx - liq values), though this may not be an equilibrium relationship. For example, IV Al-rich { h k 0 } prism sectors of sector-zoned crystals contain more Fe 3 + than IV Al-poor { 1 ¯ 11 } hourglass sectors. Moreover, IV Al-rich compositions formed during disequilibrium crystallisation are enriched in Fe 3 + . Apparent clinopyroxene-liquid Fe 2 + –Mg exchange equilibria (i.e., K D , Fe 2 + - Mg cpx - liq values) are similarly affected by disequilibrium crystallisation in our samples. Nonetheless, it is possible to reconcile our observed clinopyroxene compositions with glass Fe valence systematics estimated from olivine-liquid equilibria if we assume that K D , Fe 2 + - Mg cpx - liq values lies closer to experimentally reported values of 0.24 - 0.26 than values of ∼ 0.28 returned from a general model. In this case, olivine-liquid and clinopyroxene-liquid equilibria record equivalent narratives, with one of our glassy samples from Iceland recording evolution under f O 2 conditions about one log unit above fayalite-magnetite-quartz (FMQ) equilibrium (i.e., ∼ FMQ+1) and our glassy Azorean sample recording evolution under significantly more oxidising conditions (≥ FMQ+2.5) before experiencing syn-eruptive reduction, likely as a result of SO 2 degassing; our other glassy sample from Iceland was also affected by reductive SO 2 degassing. Overall, our findings demonstrate that the Fe valence systematics of clinopyroxene crystals can record information about the conditions under which OIBs evolve, but that further experimental work is required to properly disentangle the effects of magma composition, disequilibrium and f O 2 conditions on clinopyroxene-liquid equilibria involving Fe 2 + and Fe 3 + . [ABSTRACT FROM AUTHOR]

In this study, 3,4-diaminobenzoic acid (DABA) was introduced into the porphyrin metal–organic framework (PCN-224) for the first time to prepare a ratiometric fluorescent probe (PCN-224-DABA) to quantitatively detect ferric iron (Fe(III)) and selenium (IV) (Se(IV)). The fluorescence attributed to the DABA of PCN-224-DABA at 345 nm can be selectively quenched by Fe(III) and Se(IV), but the fluorescence emission peak attributed to tetrakis (4-carboxyphenyl) porphyrin (TCPP) at 475 nm will not be disturbed. Therefore, the ratio of I345nm/I475nm with an excitation wavelength of 270 nm can be designed to determine Fe(III) and Se(IV). After the experimental parameters were systematically optimized, the developed method shows good selectivity and interference resistance for Fe(III) and Se(IV) detection, and has good linearity in the ranges of 0.01–4 μM and 0.01–15 μM for Fe(III) and Se(IV) with a limit of detection of 0.045 μM and 0.804 μM, respectively. Furthermore, the quenching pattern was investigated through the Stern–Volmer equation, and the results suggest that both Se(IV) and Fe(III) quenched on PCN-224-DABA can be attributed to the dynamic quenching. Finally, the constructed ratiometric fluorescent probe was applied in the spiked detection of lake water samples, which shows good applicability in real sample analysis. Moreover, the Fe(III) and Se(IV) contents in spinach and selenium-enriched rice were determined, respectively.

In the framework of the H2020 project CROCODILE, the recovery of Co from oxidized ores by reductive bioleaching has been studied. The objective was to reduce Fe(III) to Fe(II) to enhance the dissolution of Co from New-Caledonian limonitic laterites, mainly composed of goethite and Mn oxides. This study focused on the Fe(III) bioreduction which is a relevant reaction of this process. In the first step, biomass growth was sustained by aerobic bio-oxidation of elemental sulfur. In the second step, the biomass anaerobically reduced Fe(III) to Fe(II). The last step, which is not in the scope of this study, was the reduction of limonites and the dissolution of metals. This study aimed at assessing the Fe(III) bioreduction rate at 35°C with a microbial consortium composed predominantly of Sulfobacillus (Sb.) species as the iron reducers and Acidithiobacillus (At.) caldus. It evaluated the influence of the biomass concentration on the Fe(III) bioreduction rate and yield, both in batch and continuous mode. The influence of the composition of the growth medium on the bioreduction rate was assessed in continuous mode. A mean Fe(III) bioreduction rate of 1.7 mg·L-1·h-1 was measured in batch mode, i.e., 13 times faster than the abiotic control (0.13 mg·L-1·h-1). An increase in biomass concentrations in the liquid phase from 4 × 108 cells·mL-1 to 3 × 109 cells·mL-1 resulted in an increase of the mean Fe(III) bioreduction rate from 1.7 to 10 mg·L-1·h-1. A test in continuous stirred tank reactors at 35°C resulted in further optimization of the Fe(III) bioreduction rate which reached 20 mg·L-1·h-1. A large excess of nutrients enables to obtain higher kinetics. The determination of this kinetics is essential for the design of a reductive bioleaching process. [ABSTRACT FROM AUTHOR]

Abstract The lunar surface and interior are highly reducing, resulting in the virtually absence of ferric ion. However, recent studies suggest the presence of ferric iron in lunar samples, and in most cases they were found in amorphous silicates (e.g., glass beads) measured by TEM–EELS. In this work, we conducted a systematic TEM–EELS analysis on the iron valence states of Chang’e-5 impact glass beads. The Fe3+/ΣFe ratio of each silicate glass sample was determined from integral intensity of Fe L3 and L2 edge. The measurements show a positive correlation between the dwell time and Fe3+/ΣFe ratio, which reveals that ferric iron can be significantly produced by electron beam bombardment under routine analytical condition. The calculated Fe3+/ΣFe with short dwell times (≤ 20 ms) in our Chang’e-5 impact glass beads show no detectable inherent ferric iron, suggesting that the ferric iron is not ubiquitous as previously reported. It is obvious that a careful control of experiment conditions is critical to determine the inherent redox state of other beam-sensitive terrestrial and extraterrestrial samples. Graphical Abstract

In the framework of the H2020 project CROCODILE, the recovery of Co from oxidized ores by reductive bioleaching has been studied. The objective was to reduce Fe(III) to Fe(II) to enhance the dissolution of Co from New-Caledonian limonitic laterites, mainly composed of goethite and Mn oxides. This study focused on the Fe(III) bioreduction which is a relevant reaction of this process. In the first step, biomass growth was sustained by aerobic bio-oxidation of elemental sulfur. In the second step, the biomass anaerobically reduced Fe(III) to Fe(II). The last step, which is not in the scope of this study, was the reduction of limonites and the dissolution of metals. This study aimed at assessing the Fe(III) bioreduction rate at 35°C with a microbial consortium composed predominantly of Sulfobacillus (Sb.) species as the iron reducers and Acidithiobacillus (At.) caldus. It evaluated the influence of the biomass concentration on the Fe(III) bioreduction rate and yield, both in batch and continuous mode. The influence of the composition of the growth medium on the bioreduction rate was assessed in continuous mode. A mean Fe(III) bioreduction rate of 1.7 mg·L−1·h−1 was measured in batch mode, i.e., 13 times faster than the abiotic control (0.13 mg·L−1·h−1). An increase in biomass concentrations in the liquid phase from 4 × 108 cells·mL−1 to 3 × 109 cells·mL−1 resulted in an increase of the mean Fe(III) bioreduction rate from 1.7 to 10 mg·L−1·h−1. A test in continuous stirred tank reactors at 35°C resulted in further optimization of the Fe(III) bioreduction rate which reached 20 mg·L−1·h−1. A large excess of nutrients enables to obtain higher kinetics. The determination of this kinetics is essential for the design of a reductive bioleaching process.

Clinopyroxene is a major rock forming mineral capable of incorporating diverse metal cations. As a consequence, clinopyroxene preserves valuable archives of magmatic processes. Understanding clinopyroxene is thus essential for understanding Earth's wider chemical evolution. However, knowledge about the relative abundances of ferrous and ferric iron in magmatic clinopyroxene remains sparse because it is not currently possible to routinely measure the valence of iron in clinopyroxene crystals without either separating single crystals for bulk analysis or securing access to Mössbauer spectroscopy or a synchrotron radiation source to perform in-situ microanalysis. This is despite magmatic clinopyroxene crystals often containing appreciable quantities of ferric iron that affect its stability and behaviour in currently ill-constrained ways and limit our ability to exploit its chemistry to robustly reconstruct conditions of magma storage and evolution. Here we integrate optimised electron probe microanalysis and Mössbauer spectroscopy on endmember and single-crystal clinopyroxene samples to re-evaluate previously discredited approaches for estimating clinopyroxene ferric iron contents by stoichiometry. By ensuring that we measured all major and minor elements in clinopyroxene crystals with sufficient precision, we show that it is possible to readily obtain stoichiometric estimates of clinopyroxene ferric-to-total iron ratios with similar precisions to those derived from Mössbauer spectroscopy (1 σ ∼ 3.5% absolute). Being able to robustly determine clinopyroxene ferric iron contents enables us to propose a new empirical scheme for assigning clinopyroxene components that explicitly accounts for ferric iron, which is primarily hosted within esseneite component (CaFe 3 + AlSiO 6 ) in clinopyroxenes dominated by quadrilateral components and aegirine component (NaFe 3 + Si 2 O 6 ) in alkali clinopyroxenes. Our new scheme provides a framework for documenting the full spectrum of clinopyroxene compositions in both natural and experimental systems when analyses are performed with sufficient precision. [ABSTRACT FROM AUTHOR]

Iron acquisition is an essential process of cell physiology for biological systems. In Klebsiella pneumoniae, the siderophore and ferric-acquisition ABC (ATP-Binding-Cassette) transporter KfuABC is utilized for iron uptake. Initial recognition of the various ferric sources in periplasm and transportation across the cytoplasmic membrane is performed by the substrate-binding protein (SBP) KfuA. Here we report the 2.0 Å resolution crystal structure of KfuA from K. pneumoniae, which crystallizes in the space group P12 1 1 with a single monomer in the asymmetric unit. A bound metal ion reveals the residues required for binding ferric ions. Binding analysis shows that ferric iron and the iron-mimicking gallium bind with high affinity to KfuA. Growth curves show that gallium inhibits growth of K. pneumoniae whereas ferric iron enhances it. This work suggests a mechanism whereby gallium effectively competes with ferric iron, disrupting iron-dependent biological functions via binding to KfuA and leading to heightened antimicrobial efficacy. Significantly, humans lack equivalent ABC transporters like SBP KfuA, underscoring the potential of KfuA as an attractive target for therapeutic intervention. • We determined the 2.0 Å crystal structure of K. pneumoniae KfuA. • A bound metal ion reveals the residues required for binding ferric ions. • Ferric iron and the iron-mimicking gallium bind with high affinity to KfuA. • Gallium inhibits growth of K. pneumoniae whereas ferric iron enhances it. • KfuA is a potential target for therapeutic intervention using gallium. [ABSTRACT FROM AUTHOR]

We investigated the compositions of a suite of 361 chrome-bearing spinels from spinel peridotites, ophiolitic mantle chromitites and from layered igneous intrusions in which the Fe2+/Fe3+ ratio has been determined by Mössbauer spectroscopy. We explore the crystal-chemical controls on the distribution of Fe3+ and on mineral stoichiometry with regard to electron-probe correction procedures for estimating Fe3+ in spinel. We find that chrome-bearing spinels can be subdivided into three groups: a Cr–Al-rich group; a high-Fe group; and a highly oxidised group. Spinels of the Cr–Al group are found in spinel peridotites and ophiolitic mantle chromitites. They are normal spinels with a low Fe3+ content and compositions that are close to stoichiometric. Spinels in the high-Fe group are found in layered igneous intrusions. They are also normal spinels which have higher concentrations of Fe3+ on the octahedrally coordinated site than is found for the Cr–Al group. Stoichiometric calculations tend to overestimate the Fe3+ content and their compositions do not conform to the MgO–cr# correlation found in the Cr–Al group. Spinels in the highly oxidised group are found in layered intrusions and ophiolitic mantle chromitites. They have (Fe3+/ΣFe)Möss > 0.4 and high Cr (cr# > 0.5), but relatively low Fe2+ (fe# 0.24–0.56). Stoichiometric calculations tend to underestimate the Fe3+ content. They represent normal spinels in which tetrahedrally coordinated Fe2+ has been oxidised to Fe3+. Our data show that spinels with greater Cr and Fe are sufficiently different in their crystal chemistry from the aluminous spinels to indicate that the EPMA correction procedures developed for Fe3+ in aluminous spinels on the basis of the Cr/Al ratio, and used in oxy-thermobarometry, are inappropriate for Cr-rich and Fe-rich compositions. [ABSTRACT FROM AUTHOR]

The lunar surface and interior are highly reducing, resulting in the virtually absence of ferric ion. However, recent studies suggest the presence of ferric iron in lunar samples, and in most cases they were found in amorphous silicates (e.g., glass beads) measured by TEM–EELS. In this work, we conducted a systematic TEM–EELS analysis on the iron valence states of Chang'e-5 impact glass beads. The Fe3+/ΣFe ratio of each silicate glass sample was determined from integral intensity of Fe L3 and L2 edge. The measurements show a positive correlation between the dwell time and Fe3+/ΣFe ratio, which reveals that ferric iron can be significantly produced by electron beam bombardment under routine analytical condition. The calculated Fe3+/ΣFe with short dwell times (≤ 20 ms) in our Chang'e-5 impact glass beads show no detectable inherent ferric iron, suggesting that the ferric iron is not ubiquitous as previously reported. It is obvious that a careful control of experiment conditions is critical to determine the inherent redox state of other beam-sensitive terrestrial and extraterrestrial samples. [ABSTRACT FROM AUTHOR]

Chloritoid and kyanite coexist in metapelites from the high‐pressure/low‐temperature Massa Unit in the Alpi Apuane metamorphic complex (Northern Apennines, Italy). The composition of chloritoid is extremely variable throughout the Massa Unit. Fe‐chloritoid occurs in association with hematite‐free, graphite‐bearing schists, whereas strongly zoned Fe‐Mg chloritoid is found with hematite and kyanite. We investigated the effect of different bulk Fe2O3 contents in controlling chloritoid composition through phase equilibria modelling of four selected samples, representative of the different chloritoid‐bearing parageneses found in the Massa Unit. The ferric iron content, measured through wet chemical titration, ranges from 0 (graphite‐chloritoid schist) to 73% of the total iron (hematite‐chloritoid schist). We show that Mg‐rich chloritoid compositions and stability of kyanite at greenschist to blueschist facies conditions can be reproduced in the MnO–Na2O–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O (MnNKFMASHTO) chemical system only considering the presence of significant amounts of ferric iron as part of the bulk composition. The stabilization of kyanite at lower grade is directly linked to the presence of Fe2O3, which renders the reactive bulk rock composition effectively enriched in Al2O3 with respect to Fe and Mg. We also document that high Fe2O3 contents exacerbate the effect of chloritoid fractionation, producing strongly zoned Fe‐Mg‐chloritoid grains. Finally, the P–T modelling of the Massa Units performed in this study allows, for the first time, the recognition of a two‐stage evolution at peak conditions, with an earlier pressure peak (1.2–1.3 GPa at 350–400°C), and a later thermal peak (0.7–1.1 GPa at 440–480°C), compatible with subduction, underthrusting and exhumation of the Adria continental margin during growth of the Northern Apennine orogenic wedge. [ABSTRACT FROM AUTHOR]

Glyphosate, the most used herbicide in the world, has a residue problem that cannot be ignored. However, glyphosate itself does not have fluorescence emission and lacks the conditions for fluorescence detection. In this work, a rapid and selective fluorescence detection method of glyphosate was designed by an 'on–off–on' fluorescent switch based on a luminous covalent organic framework (L‐COF). Only the fixed concentration of Fe3+ as an intermediate could trigger the fluorescent switch and no incubation step was required. The proposed method showed good accuracy with a correlation coefficient of 0.9978. The method's limits of detection and quantitation were 0.88 and 2.93 μmol/L, which were lower than the maximum allowable residue limits in some regulations. Environmental water samples and tomatoes were selected as actual samples to verify the application in a complex matrix. A satisfactory mean recovery from 87% to 106% was gained. Furthermore, Fe3+ could induce fluorescence quenching of L‐COF through the photo‐induced electron transfer (PET) effect, while the addition of glyphosate could block the PET effect to achieve detection. These results demonstrated the proposed method had abilities to detect glyphosate and broaden the application of L‐COF. [ABSTRACT FROM AUTHOR]

Sustainable serpentine/polyamide nanocomposite (SP/PAM) was fabricated using malicious mining (serpentine chrysotile, SP Ctl) and industrial (polyamide, PA6) wastes via the electro-spinning technique. Before fabrication, the fibrous nature of Ctl was demolished through intensive grinding into nano-fractions. The successful impregnation of Ctl within PA6 via the electro-spinning technique at fixed ratios of precursor raw materials in the dissolving agent (7.5/92.5% SP/PA wt/wt solid/solid) created an internal network structure within the polymer fibers by molecular self-assembly. SP/PAM showcased its prowess in tackling the remediation of diverse dyes and Fe(III) from synthetic solutions in a batch system. Based on correlation coefficient outcomes (R2 ≈ 0.999), the pseudo-second-order equation justified the sorption data in an adequate way for all contaminants. In addition, intra-particle diffusion was not the only driving factor in the sorption process. Similarly, the Langmuir equation with maximum removal capacity (qmax) 5.97, 4.33, and 5.36 mg/g for MO, MB, and Fe(Ⅲ), respectively, defined the sorption data better than Freundlich. [ABSTRACT FROM AUTHOR]

Fomitiporia mediterranea (Fmed) is the primary Basidiomycota species causing white rot in European vineyards affected by the Esca complex of diseases (ECD). In the last few years, an increasing number of studies have highlighted the importance of reconsidering the role of Fmed in ECD etiology, justifying an increase in research interest related to Fmed's biomolecular pathogenetic mechanisms. In the context of the current re-evaluation of the binary distinction (brown vs. white rot) between biomolecular decay pathways induced by Basidiomycota species, our research aims to investigate the potential for non-enzymatic mechanisms adopted by Fmed, which is typically described as a white rot fungus. Our results demonstrate how, in liquid culture reproducing nutrient restriction conditions often found in wood, Fmed can produce low molecular weight compounds, the hallmark of the non-enzymatic "chelator-mediated Fenton" (CMF) reaction, originally described for brown rot fungi. CMF reactions can redox cycle with ferric iron, generating hydrogen peroxide and ferrous iron, necessary reactants leading to hydroxyl radical (•OH) production. These observations led to the conclusion that a non-enzymatic radical-generating CMF-like mechanism may be utilized by Fmed, potentially together with an enzymatic pool, to contribute to degrading wood constituents; moreover, indicating significant variability between strains. [ABSTRACT FROM AUTHOR]

Steel is used as reinforcement in construction materials and it is also an important component of cement-stabilized waste materials to be disposed of in deep geological repositories for radioactive waste. Steel corrosion releases dissolved Fe(II/III) species that can form corrosion products on the steel surface or interact with cementitious materials at the iron-cement interface. The thermodynamically stable Fe species in the given conditions may diffuse further into the adjacent, porous cement matrix and react with individual cement phases. Thus, the retention of Fe(II/III) by the hydrate assemblage of cement paste is an important process affecting the diffusive transport of the aqueous species into the cementitious materials. The diffusion of aqueous Fe(II/III) species from the steel surface into the adjacent cementitious material coupled with the kinetically controlled formation of iron corrosion products, such as by Fe(II) oxidation, decisively determines the extension of the corrosion front. This review summarises the state-of-the art knowledge on the interaction of ferrous and ferric iron with cement phases based on a literature survey and provides new insights and proper perspectives for future study on interaction systems of iron and cement. [ABSTRACT FROM AUTHOR]

Huiyang Wang,1,* Siqi Wang,2,* Xisong Zhu,3 Wenxiu Ding,4 Tianlun Shen,2 Hongjie Fan,1 Yanhua Zhang,5 Lijun Peng,6 Hong Yuan,6 Xiangrui Liu,7 Jun Ling,2 Jihong Sun1 1Department of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, People’s Republic of China; 2MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, People’s Republic of China; 3Department of Radiology, Quzhou Central Hospital Affiliated to Zhejiang Chinese Medical University, Quzhou, 324002, People’s Republic of China; 4Department of Ultrasound Medicine, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310003, People’s Republic of China; 5Department of Pathology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, People’s Republic of China; 6College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310030, People’s Republic of China; 7Department of Pharmacology, Zhejiang University School of Medicine, Hangzhou, 310058, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jihong Sun, Department of Radiology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310016, People’s Republic of China, Tel +13857176538, Fax +571-86006762, Email sunjihong@zju.edu.cn Jun Ling, MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, People’s Republic of China, Tel +13645717301, Fax +571-87953739, Email lingjun@zju.edu.cnPurpose: To develop an iron-based solid lipid nanoparticle (SLN) absorbable by the intestinal wall and assess the differential diagnostic value of intestinal lesions in magnetic resonance imaging (MRI).Methods: SLNs were prepared with the simultaneous loading of trivalent Fe ions (Fe3+), levodopa methyl ester (DM), and fluorescein isothiocyanate (FITC). We evaluated the particle size, loading rate, encapsulation efficiency, and cytotoxicity of SLNs. The T1 contrast effects of the FeDM-FITC-SLNs and gadolinium-based contrast agent (GBCA) were compared in different mouse models: acute ulcerative colitis (AUC), chronic ulcerative colitis (CUC), colon adenocarcinoma (COAD), and normal control. MRI was performed in the same mouse with intravenous injection of GBCA on day 1 and enema of FeDM-FITC-SLNs on day 2. The signal-to-noise ratios (SNRs) were compared using one-way analysis of variance. Tissues were then collected for histology.Results: The average particle size of FeDM-FITC-SLN was 220 nm. The mean FeDM loading rate was 94.3%, and the encapsulation efficiency was 60.3%. The relaxivity was 4.02 mM− 1·s− 1. After enema with FeDM-FITC-SLNs, MRI showed the following contrast enhancement duration: AUC = COAD > normal > CUC. Confocal fluorescence microscopy confirmed that FeDM-FITC-SLNs were mainly distributed in the intestinal mucosa and tumor capsule.Conclusion: Iron-based SLNs are promising alternatives for contrast enhancement at T1-weighted MRI and will help in the differential diagnosis of intestinal bowel diseases (IBDs).Keywords: solid lipid nanoparticles, magnetic resonance imaging, contrast agent, ferric iron, intestinal bowel diseases

Arsenic is a naturally occurring contaminant in waters, which is toxic and adversely affects human health. Therefore, treatment of water for arsenic removal is very important production of safe drinking water. Coagulation using Fe(III) salts is the most frequently applied technology for arsenic removal, but is efficient mostly for As(V) removal. As(III) removal usually requires the application of a pre-oxidation step, which is mainly conducted by chemical or biological means. In this study, we show that Fe(III) coagulation in the presence of H2O2 can be a very efficient treatment process for As(III) removal, which has been never been shown before in the literature. The results showed that addition of 8.7–43.7 mM hydrogen peroxide to Fe(III) coagulation process was able to increase the effectiveness of As(III) removal in synthetic groundwater by 15–20% providing residual concentrations well below the regulatory limit of 10 μg/L from initial As(III) concentrations of 100 μg/L, at pH 7. The enhanced coagulation process was affected by the solution pH. The removal efficiency substantially declined at alkaline pH values (pH > 8). Addition of EDTA in the absence of H2O2 had a strong inhibiting effect where the As(III) removal was almost zero when 88.38 μΜ EDTA were used. Radical quenching experiments with 50, 100 and 200 mM DMSO, methanol and 2-propanol in the H2O2-coagulation process had a slightly adverse effect on the removal efficiency. This is considered as indicative of an adsorption/oxidation of As(III) process onto or very near the surface of iron oxide particles, formed by the hydrolysis of Ferric iron ions. In practice, the results suggest that addition of H2O2 increases the As(III) removal efficiency for Fe(III) coagulation systems. This is an important finding because the pre-oxidation step can be omitted with the addition of H2O2 while treating water contaminated with As(III). [ABSTRACT FROM AUTHOR]

The impacts of curing plus antioxidant or prooxidant inclusion in model meat systems on malondialdehyde (MDA) levels detected by three different assays as spectrophotometry (M-1), test kit (M-2), and high-performance liquid chromatography (HPLC, M-3) were explored. Four different treatments that included non-cured, cured, cured plus zeaxanthin-added, and cured plus ferric iron-added meat systems were produced. MDA levels during storage recorded by M-1 were higher than both M-2 (up to 29-fold) and M-3 (up to 53-fold). The effects of curing were visibly detected by all assays, whereas the impacts of antioxidant or prooxidant addition were more obvious when determined by M-2 and M-3. Despite the variations within numerical values, both M-1 and M-2 presented strong correlations with M-3. Overall, it was concluded that spectrophotometric assays could be reliable on condition that acceptable coefficients are utilized to avoid overestimation. Besides, the simultaneous improvement and simplification of chromatographic techniques as well as rapid test kits would pave the way for their widespread use. [ABSTRACT FROM AUTHOR]

Ferric ions (Fe3+) and pyrophosphate anions (PPi) are involved in many physiological processes and play important roles in biological systems. The abnormal level of Fe3+ and PPi will cause serious damage to the environment and life. At present, the application of such probes in life, especially in vivo, is still very scarce. So, the development of a fluorescent probe to simultaneously detect Fe3+ and PPi has great significance to the health of the environment and organisms. Herein, nitrogen-doped carbon quantum dots (N-CDs) were synthesized via solvothermal treatment, using biuret and citric acid as precursors. The synthesized N-CDs showed highly selective and sensitive detection of Fe3+ through a photoluminescence quenching effect. The fluorescence of N-CDs quenched by Fe3+ could be restored with PPi, rendering the N-CDs/Fe3+ sensor promising for PPi detection ('OFF–ON'). The linear ranges of detection for Fe3+ and PPi were 3–30 and 2–12 μM, and the limits of detection were 2.71 and 1.12 μM, respectively. The practical applications of N-CDs were tested using tap water samples. Furthermore, N-CDs can be used for the detection and imaging of Fe3+ and PPi in HeLa cells and zebrafish owing to their excellent optical properties. [ABSTRACT FROM AUTHOR]

Background: Ceruloplasmin plays an important role in the regulation of iron metabolism. Ceruloplasmin is an acute-phase protein known to have many metabolic effects. Its activity increases during infection, inflammation, and compensation of oxidation. In the current study, our aim is to develop a new method for the measurement of ferroxidase activity without requiring any chromogen. Methods: Venous blood samples were collected into serum separator tubes. Ferric iron ions formed by the enzyme ferroxidase were measured, both manually and fully automatically, at the 415 nm wavelength without using chromogen. These results were compared to conventional ferroxidase measurement methods and to the immunoturbidimetric ceruloplasmin measurement method. Results: The detection limit of the new assay was 14.8 U/L. The upper limit of the linearity was 1380 U/L. Precision values were calculated for high, medium, and low levels of ferroxidase activity in serum pool. The coefficient of variation was <5% for each level. Conclusion: In the present method, chromogens are not used. With its considerably low cost and short reaction time, this method is able to provide fast results, can be performed easily, and makes accurate measurements. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a progressive movement disorder associated with brain iron (Fe) accumulation and free radicals. Brown rice (BR) is antioxidant-rich and has been shown to ameliorate oxidative stress-induced damage. The aim of this study was to investigate the effects of BR compared to white rice (WR) on Fe-induced PD in a fruit fly model. Three-day-old male adult flies were divided into two groups: one on a normal diet and the other on Fe-diet (1 mmol/L) for 10 days to induce PD. After 10 days, the Fe-fed flies were redistributed into four groups: one on normal diet (Fe group), while the others were treated with BR (Fe + BR group), WR (Fe + WR group), or L-3,4-dihydroxyphenylalanine (L-dopa) (Fe + L-dopa group) for 5 days. Similarly, the flies initially on a normal diet were separated into four groups: one on normal diet (Control group), while the others were treated with BR (BR group), WR (WR group), or L-dopa (L-dopa group) for 5 days. Finally, Fe levels, dopamine, malonaldehyde (MDA), and antioxidant enzymes were measured, and the mRNA levels of antioxidant and Fe metabolism genes were assessed. BR significantly improved motor and cognitive functions, decreased fly head MDA and Fe levels, and increased antioxidant enzyme levels in comparison to the Fe and WR groups. Similarly, BR upregulated the mRNA levels of antioxidant genes: catalase, GPx, Nrf2, and DJ-1. The results suggest that BR could potentially reduce morbidities associated with PD possibly due to its bioactive compounds compared to WR., Competing Interests: The authors declare no competing interests.

Nepheline is a nominally anhydrous aluminosilicate that typically contains an impurity of ferric iron replacing aluminum in tetrahedral sites. However, previous researchers noted the constant presence of ferrous iron in the chemical composition of nepheline from the rocks of the Khibiny and Lovozero massifs (Kola Peninsula, Russia). We have carried out microprobe, spectroscopic, chemical and crystal chemical studies of nepheline from the Lovozero massif. We have established the presence of molecular water in nepheline, and also that the incorporation of ferrous iron into nepheline crystal structure is associated with the simultaneous increasing of the coordination number from four to five (or six) due to the inclusion of the 'additional' water molecules that form point [FeO4(H2O)n]-defects (where n = 1, 2) in the tetrahedral framework. The nepheline iron content is closely related to the presence of small needle-like aegirine inclusions. The total iron content in nepheline saturated with aegirine needles is approximately an order of magnitude lower than in nepheline free from aegirine inclusions. Most likely the aegirine inclusions in nepheline are formed as a result of the decomposition of the nepheline–"iron nepheline" solid solution. We propose that this process is triggered by the oxidation of ferrous iron in the crystal structure of nepheline. [ABSTRACT FROM AUTHOR]

Adaptation and microbial attachment mechanisms for the degradation of sulfide ores are mediated by the production of extracellular polymeric substances (EPS) and their role in biofilm formation. EPS production responds to induction mechanisms associated with environmental conditions. In this study, the double induction of EPS with galactose and high ferric iron concentrations in planktonic cells of Acidithiobacillus ferrooxidans, and their attachment on the surface of a polymetallic sulfide ore from Bella Rica-Azuay in Ecuador were evaluated. A. ferrooxidans cells were previously adapted to different concentrations of galactose [0, 0.15, and 0.25% (w/v)], using two ferrous iron concentrations as an energy source (9 and 18 g L-1) in a 9K culture medium. EPS production and its effect on mineral attachment were determined at the time point of maximal growth. The results obtained show a maximum cell attachment of 94.1% within 2 h at 0.15% of galactose and 18 g·L-1 of ferric iron concentration, compared to 71.4% without galactose and 9 g·L-1 of ferric iron. The maximum concentration of EPS was obtained with a 0.25% galactose concentration; however, it did not result in greater attachment compared to 0.15% galactose concentration. Through the combined induction of low galactose concentration and high ferric iron concentration, the percentage of bacterial attachment can be increased and, therefore, a possible increase in the rate of biooxidation and bioleaching could be obtained. [ABSTRACT FROM AUTHOR]

Three sets of experiments were performed to test the stability and geologic importance of ferric (FeIII) chloride complexes in acidic, Cl-rich solutions at 150–300 °C, p = p sat. Experiment Set A used the change in solubility of AgCl(s) in the presence of FeCl 3 or FeCl 2 to determine the stoichiometry of Fe(III) and Fe(II) chloride complexes at ΣCl = 0.1–3.0 molal. Results show that FeCl 4 − and FeCl 2 (aq) are the dominant Fe(III) and Fe(II) species, respectively, at T > 200 °C and ΣCl ≥ 1 m. Set B experiments used the solubility of elemental gold as a redox sensor to determine the a O 2 of the FeCl 4 −/FeCl 2 (aq) boundary and log K values of +6.56 and +7.19 for the following reaction at 250 and 300 °C, respectively: FeCl 2 (aq) + ¼O 2 (g) + 2Cl− + H+ = FeCl 4 − + ½H 2 O(l). Ferric chloride complexes are stable under conditions of a Cl−, a O 2 , and pH where gold is soluble as AuCl 2 −. Set C experiments measured the solubility of hematite in NaCl-HCl solutions at 200–300 °C by preparing a series of silica tubes with identical matrix chemistry (0.9 m NaCl + 0.1 m HCl) and increasing concentration of FeCl 3. Hematite saturation was constrained by the tube with the lowest FeCl 3 concentration that precipitated hematite at high temperature. Set C results were used to compute log K values of +3.6, +5.2, and + 7.4 for the following reaction at 200, 250 and 300 °C, respectively: 0.5Fe 2 O 3 (s) + 4Cl− + 3H+ = FeCl 4 − + 1.5H 2 O. Hematite solubility as FeCl 4 − is independent of redox state, and increases quickly with an increase in temperature, increase in Cl− concentration (power of 4), and decrease in pH (power of 3). Concentrations in excess of 100 mg/L ΣFe are attainable under geologically realistic conditions. Once formed, FeCl 4 − is an extremely effective oxidizing agent, capable of destabilizing any sulfide mineral and dissolving Fe, Au, and other metals (e.g., Cu, Pt, Pd) as chloride complexes. In deep hydrothermal systems, FeCl 4 − is a more viable oxidant than dissolved O 2 gas, although its presence requires a source area with abundant hematite and a lack of reductants such as organic carbon, sulfides, or silicate minerals containing ferrous iron. Dissolved ferric chloride could be an important and previously overlooked reactant in the formation of certain types of hematite-rich hydrothermal mineral deposits, including iron oxide-copper–gold (IOCG) deposits. [ABSTRACT FROM AUTHOR]

Adaptation and microbial attachment mechanisms for the degradation of sulfide ores are mediated by the production of extracellular polymeric substances (EPS) and their role in biofilm formation. EPS production responds to induction mechanisms associated with environmental conditions. In this study, the double induction of EPS with galactose and high ferric iron concentrations in planktonic cells of Acidithiobacillus ferrooxidans, and their attachment on the surface of a polymetallic sulfide ore from Bella Rica-Azuay in Ecuador were evaluated. A. ferrooxidans cells were previously adapted to different concentrations of galactose [0, 0.15, and 0.25% (w/v)], using two ferrous iron concentrations as an energy source (9 and 18 g L–1) in a 9K culture medium. EPS production and its effect on mineral attachment were determined at the time point of maximal growth. The results obtained show a maximum cell attachment of 94.1% within 2 h at 0.15% of galactose and 18 g⋅L–1 of ferric iron concentration, compared to 71.4% without galactose and 9 g⋅L–1 of ferric iron. The maximum concentration of EPS was obtained with a 0.25% galactose concentration; however, it did not result in greater attachment compared to 0.15% galactose concentration. Through the combined induction of low galactose concentration and high ferric iron concentration, the percentage of bacterial attachment can be increased and, therefore, a possible increase in the rate of biooxidation and bioleaching could be obtained.

Iron deficiency (ID), with or without anemia, is commonly found worldwide and affects the health and wellbeing of pregnant and nonpregnant women. Symptoms of ID- which include fatigue, pica (ice craving), restless legs syndrome, poor concentration and work function, increased susceptibility to infection, and cardiovascular stress- can cause significant morbidity and reduced quality of life. The etiologies of iron deficiency in women are usually specific to each community. In the developing world, iron deficiency is usually associated with poor iron intake and parasitic infections, whereas in higher income regions, iron deficiency is typically the result of heavy, abnormal uterine bleeding, and pregnancy. Iron-poor diets and poor iron absorption resulting from gut disorders can also play a role. Diagnosis of iron deficiency is usually straightforward and characterized by a low ferritin level; however, the diagnosis can be challenging in women with concomitant inflammatory disorders, in which case a low percent transferrin saturation, performed after an overnight fast, can inform on the need for iron. Therapy is frequently initiated with oral iron salts; however, use of these oral regimens is commonly associated with adverse events, mostly gastrointestinal in nature, that have been shown to adversely impact compliance, continuation, and the achievement of therapeutic goals. A further impediment to the effectiveness of oral iron is its poor absorption because of comorbidity (i.e., celiac disease, gastritis, etc.), surgery (bariatric), or physiologic inhibitory mechanisms. As such, intravenous (IV) iron regimens are increasingly being used to treat ID, as such regimens have been shown to avoid the gastrointestinal adverse events commonly associated with oral regimens. Indeed, IV iron has been shown to provide adequate iron replacement in women with functional iron deficiencies as well as those with ID resulting from inflammatory disorders- patients often resistant to oral iron therapy. More recent IV iron regimens have been shown to provide iron replacement in a safe and effective manner, being associated with more salutary adverse event profiles than earlier IV iron regimens. In fact, these iron regimens can provide a complete replacement dose in a single 15–60-min visit. [ABSTRACT FROM AUTHOR]

Chitosan (CS) was modified with ferric chloride hexahydrate (FeCl3·6H2O) and sodium laurylsulfonate (SLS) to prepare the compound adsorbent CS-Fe-SLS. Taking Cr(VI) as the target pollutant, the influence of different factors (solution pH, adsorption time, initial adsorption concentration and coexisting ions) were investigated. The results showed that the optimal pH value was 3.0; the adsorption equilibrium was reached at 120 min, with both physical and chemical process being involved in the adsorption process; the maximum adsorption value was 131.91 mg/g, with the adsorption being both single-layer and multi-layer adsorption; Cl−, NO3- and SO42- had little effect on adsorption, CO32- reduced it and Cu(II) increased it. The characterization results of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction showed that CS-Fe-SLS and chitosan had different morphological characteristics: in contrast with chitosan, CS-Fe-SLS had a larger volume and more flakes on the surface. CS-Fe-SLS was significantly lower in crystallinity than chitosan, and was more irregular and amorphous in shape, and the experimental results showed that CS-Fe-SLS had better adsorption capacity for Cr(VI). The adsorption Cr(VI) was related to -NH and -OH on the material. Some Cr(VI) was reduced to Cr(III) during the adsorption process.

Wastewater pollution with detergents is one of the environmental problems associated with the rational use of water resources. The existing methods of physicochemical wastewater treatment, despite their efficiency, are open to secondary environmental pollution. Biological coagulation/flocculation methods are widely used with the plant waste. The aim of this research was the use of ferric iron obtained by means of the bacterial-chemical method and bentonite to reduce the chemical oxygen demand in the wastewater containing detergents. It was identified that the use of Fe2(SO4)3 obtained using the bacterial-chemical method with thionic bacteria Acidithiobacillus ferrooxidans BIT 1 and bentonite as a clay material is promising. At the same time, it was found that the highest reduction degree in the chemical oxygen demand - 88.1 ± 7.9% in wastewater was noted in the variation where the bacterialchemical ferric iron in the amount of 1.75 g/L was used in combination with bentonite in the amount of 600 mg/L. [ABSTRACT FROM AUTHOR]

ABSTRACT. The main aim of this study was to assess the effects of ferrous iron oxidation, hydrolysis and precipitation of the ferric iron on the mechanisms of arsenate removal from acid mine drainage. The study was realized at the pH range 2,0 – 6,5. H2O2 was the oxidant used in the chemical test. A mixed culture of mesophilic iron–oxidizing chemolithotrophic bacteria (Acidithiobacillus ferrooxidans, Leptospirillum ferroxidans) carried out the ferrous oxidation in the biological test. NaOH was used as an alkalizing agent which triggered the ferric iron hydrolysis and precipitation. The results showed that the total content of retained arsenic by ferric iron hydrous oxides and its speciation as geochemical fractions depended on the iron and phosphate concentrations in acid solution. The results showed that phosphate concentration lower than 6 mg/ L limited the ferrous iron oxidation rate. At the tested experimental conditions, arsenic sorption by formed ferric iron hydrous oxides was the main mechanism for its removal from acid mine drainage, as the ratio between iron and phosphate determined the proportions between the geochemical fractions of scavenged arsenic.

Fomitiporia mediterranea (Fmed) is the primary Basidiomycota species causing white rot in European vineyards affected by the Esca complex of diseases (ECD). In the last few years, an increasing number of studies have highlighted the importance of reconsidering the role of Fmed in ECD etiology, justifying an increase in research interest related to Fmed’s biomolecular pathogenetic mechanisms. In the context of the current re-evaluation of the binary distinction (brown vs. white rot) between biomolecular decay pathways induced by Basidiomycota species, our research aims to investigate the potential for non-enzymatic mechanisms adopted by Fmed, which is typically described as a white rot fungus. Our results demonstrate how, in liquid culture reproducing nutrient restriction conditions often found in wood, Fmed can produce low molecular weight compounds, the hallmark of the non-enzymatic “chelator-mediated Fenton” (CMF) reaction, originally described for brown rot fungi. CMF reactions can redox cycle with ferric iron, generating hydrogen peroxide and ferrous iron, necessary reactants leading to hydroxyl radical (•OH) production. These observations led to the conclusion that a non-enzymatic radical-generating CMF-like mechanism may be utilized by Fmed, potentially together with an enzymatic pool, to contribute to degrading wood constituents; moreover, indicating significant variability between strains.

Electrochemical tests were developed to investigate the electrochemical dissolution behavior of gold and its main coexistent sulfide minerals in acid thiocyanate solutions. The optimal leaching conditions for gold in acidic thiocyanate system were pH 2, 0.15 mol·L−1 thiocyanate and 0.2 g·L−1 Fe3+. Fe3+ addition to the acidic thiocyanate system promoted gold dissolution significantly, arsenopyrite dissolution was inhibited, chalcopyrite dissolution was increased, and the dissolution behavior of other associated minerals remained mostly unchanged. Thiocyanate made gold and associated mineral leaching easier. The galvanic corrosion effect of gold and its main coexistent sulfide minerals in an acidic thiocyanate-free system was that the chalcocite, arsenopyrite and pyrite acted as a cathode to reduce anodic gold dissolution; galena as an anode undergoes oxidation to inhibit anodic gold dissolution. There was almost no galvanic corrosion behavior between stibnite, yellow sphalerite and black sphalerite and gold. Thiocyanate addition changed the galvanic corrosion behavior of stibnite and yellow sphalerite in the thiocyanate system, which inhibited anodic gold dissolution. In the acidic thiocyanate system in the presence of ferric iron, the arsenopyrite promoted anodic gold dissolution, the chalcocite and gold were mostly free of galvanic corrosion, and the remaining minerals inhibited anodic gold dissolution. [ABSTRACT FROM AUTHOR]

Bridgmanite may contain a large proportion of ferric iron in its crystal structure in the forms of FeFeO3 and MgFeO2.5 components. We investigated the pressure dependence of FeFeO3 and MgFeO2.5 contents in bridgmanite coexisting with MgFe2O4‐phase and with or without ferropericlase in the MgO‐SiO2‐Fe2O3 ternary system at 2,300 K, 33 and 40 GPa. Together with the experiments at 27 GPa reported in Fei et al. (2020, https://doi.org/10.1029/2019GL086296), our results show that the FeFeO3 and MgFeO2.5 contents in bridgmanite decrease from 7.6 to 5.3 mol % and from 2 to 3 mol % to nearly zero, respectively, with increasing pressure from 27 to 40 GPa. Accordingly, the total Fe3+ decreases from 0.18 to 0.11 pfu. The formation of oxygen vacancies (MgFeO2.5 component) in bridgmanite is therefore dramatically suppressed by pressure. Oxygen vacancies can be produced by ferric iron in Fe3+‐rich bridgmanite under the topmost lower mantle conditions, but the concentration should decrease rapidly with increasing pressure. The variation of oxygen‐vacancy content with depth may potentially affect the physical properties of bridgmanite and thus affect mantle dynamics. Plain Language Summary: Bridgmanite is the most abundant mineral in the Earth's lower mantle. Although its basic chemical formula is MgSiO3, large amounts of Fe3+ can be added in the following two ways: (1) Two Fe3+ replace Mg2+ and Si4+ and form the FeFeO3 component. This is called charge‐coupled substitution because the overall charge does not change. (2) One Fe3+ replaces one Si4+ and forms the MgFeO2.5 component. Here the loss of positive charge is compensated by a loss of oxygen and is therefore called oxygen‐vacancy substitution. In this study, we measured the effect of pressure on the abundance of these two components of bridgmanite. We found that the MgFeO2.5 content decreases greatly with increasing pressure. Some oxygen sites may therefore be vacant in bridgmanite at the top of lower mantle, but the concentration of oxygen vacancies should decrease rapidly in deeper regions. The decrease of oxygen‐vacancy concentration in bridgmanite will change the nature of the lower mantle, for example, rocks will become harder, and electrical conductivity will decrease with increasing depth. Key Points: MgFeO2.5, FeFeO3, and total Fe3+ contents in bridgmanite decrease with increasing pressureFe3+‐linked oxygen vacancies in bridgmanite are destabilized by increasing pressureMgFeO2.5 can be formed in Fe3+‐rich bridgmanite under the topmost lower mantle conditions [ABSTRACT FROM AUTHOR]

Jeffbenite, ideally Mg3Al2Si3O12, has been identified as inclusions in super-deep diamonds originating from depths that exceed 300 km. Although Mg-end member jeffbenite has limited stability at upper-mantle conditions, iron-bearing jeffbenite may have broader P–T stability that extends to the transition zone or uppermost lower mantle, incorporating significant amounts of ferric iron. Using synchrotron-based, single-crystal X-ray diffraction (XRD) and synchrotron Mössbauer spectroscopy (SMS) at pressures up to 29 GPa, we report the crystal structure, compressibility, and likely spin transition of iron in ferromagnesian jeffbenite (Mg2.32Al0.03Fe2+1.28Fe3+1.77Si2.85O12). High-pressure structure refinements reveal that Fe3+ substitution for Si in the T2 site, which shares edges with the M2 octahedron, likely stabilizes jeffbenite at high pressure, because it increases the cation-to-cation distance between these sites. Although ferromagnesian jeffbenite does not undergo a structural phase transition below 30 GPa, SMS hyperfine parameters suggest the onset of an electronic spin transition of iron from high-spin (HS) to low-spin (LS) at around 22 GPa, which may increase its stability at high pressures. Pressure–volume data were fit to a third order Birch–Murnaghan equation of state, resulting in V0 = 816.54(9), KT0 = 181.54(1.39), and K T 0 ′ = 2.76(14). These equation of state parameters are applicable to evaluating the encapsulation pressures of super-deep diamonds. The density and bulk modulus of ferromagnesian jeffbenite are similar to or higher than pyrope–almandine, pyrope–majorite, and skiagite–majorite solid solution garnets, further suggesting that jeffbenite may be an important ferric–iron silicate in the deeper parts of the mantle transition zone and uppermost lower mantle. However, future studies on the influence of temperature and oxidation state on the stability and equations of state of iron-bearing jeffbennite are still needed to determine what role, if any, jeffbenite plays in transition-zone mineralogy. [ABSTRACT FROM AUTHOR]

Background: Ceruloplasmin plays an important role in the regulation of iron metabolism. Ceruloplasmin is an acute-phase protein known to have many metabolic effects. Its activity increases during infection, inflammation, and compensation of oxidation. In the current study, our aim is to develop a new method for the measurement of ferroxidase activity without requiring any chromogen. Methods: Venous blood samples were collected into serum separator tubes. Ferric iron ions formed by the enzyme ferroxidase were measured, both manually and fully automatically, at the 415 nm wavelength without using chromogen. These results were compared to conventional ferroxidase measurement methods and to the immunoturbidimetric ceruloplasmin measurement method. Results: The detection limit of the new assay was 14.8 U/L. The upper limit of the linearity was 1380 U/L. Precision values were calculated for high, medium, and low levels of ferroxidase activity in serum pool. The coefficient of variation was

The aquatic chemistry of iron involves many environmental aspects because dissolved iron is present as ferrous and ferric ion and the equilibrium between these two forms depends on many natural or antropogenic factors. This paper aims to provide a brief introduction to chemistry of iron in an oligotrophic lake, a new topic in this domain. A number of 28 sampling were taken from Cătămărăști Lake, Botoșani (Romania). The main physico-chemical properties showed that the acidity, dissolved oxygen, electrical conductivity and saturation satisfied the water quality criteria for this ecosystem. The results for dissolved iron species indicated that there is no strictly correlation with the variation of oxygen content. Thus, for the samples from NE shore, the contents of ferrous iron are bigger than of ferric iron, for the samples from SW shore the contents are almost equal, because of the low contents of oxygen. For the samples from the middle and from downstream of the lake, the contents of ferric iron are bigger than of ferrous iron, due to the oxygen content recorded. [ABSTRACT FROM AUTHOR]

The crystal chemistry of ten well‐characterized bridgmanite single‐crystals with Fe and Al contents ranging from 0 to 0.40 atoms per two‐cation formula units were investigated by single‐crystal X‐ray diffraction. Structural refinements indicate that Fe3+ and Al mainly occupy the Mg and Si sites, respectively, when present in similar proportions. Molar volumes of bridgmanite endmember components were refined using data from this and previous studies and found to decrease in the order Fe3+Fe3+O3 > MgFe3+O2.5 > Fe3+AlO3 > MgAlO2.5 > AlAlO3 > Fe2+SiO3 > MgSiO3. Fe3+AlO3 charge‐coupled substitution leads to an anisotropic increase of B‐O bond distances, resulting in more distorted octahedral B sites and in a more significant increase of the c‐axis with respect to the a‐ and b‐axes. Valence bond calculations indicate that the A site is more compressible than the B site for all bridgmanite samples studied, implying that octahedral tilting and distortion will dominate the bridgmanite compression mechanism. Guided by these crystal chemical observations, bulk moduli of bridgmanite endmember components were estimated using results of previous studies. The volume changes of equilibria controlling the speciation of bridgmanite components were then calculated at conditions relevant to the top of Earth's lower mantle. The proportion of oxygen vacancy components is predicted to decrease with pressure. While the stability of the bridgmanite Fe3+AlO3 component will drive charge disproportionation to produce iron metal at the top of the lower mantle, this appears to be much less favorable by 50 GPa. An increase in the proportion of the Fe3+Fe3+O3 bridgmanite component, however, may favor the formation of iron metal at higher pressures. Plain Language Summary: Fe‐Al‐bearing MgSiO3 bridgmanite is the most abundant mineral in the Earth's lower mantle. Its physical and chemical properties, which are closely related to its crystal structure, play a major role in controlling processes in the Earth's lower mantle. In this study, we synthesized several bridgmanite single crystals with various compositions, which allowed the substitution mechanisms and site occupancies of Fe and Al in the structure to be determined. The changes in volume and structure resulting from the different substitution mechanisms were identified and can be used to explain the compressibility of different bridgmanite endmembers. The effect of pressure on the composition of bridgmanite was then predicted. We found that pressure should favor charge‐coupled substitution where 3+ cations enter both the Mg and Si cation sites. The alternative mechanism, where 3+ cations enter the Si site and oxygen vacancies are created, is not favored with pressure. Also Fe3+ and Al may become disordered onto both the Mg and Si sites as pressure increases. The formation of Fe metal through reduction and oxidation of Fe2+ may be suppressed at greater depths in the lower mantle, therefore, the deep lower mantle may be less reduced than the shallower region. Key Points: The molar volumes of bridgmanite endmember components were determined to be Fe3+Fe3+O3 > MgFe3+O2.5 > Fe3+AlO3 > MgAlO2.5 > AlAlO3 > Fe2+SiO3 > MgSiO3Fe3+ and Al mainly occupy the A and B sites, respectively, at 25 GPa when Fe3+ = Al but disordering may be favored at higher pressuresPressure favors charge‐coupled substitution over oxygen vacancy formation and may suppress Fe metal precipitation [ABSTRACT FROM AUTHOR]

The chemistry of bridgmanite (Brg), especially the oxidation state of iron, is important for understanding the physical and chemical properties, as well as putting constraints on the redox state, of the Earth's lower mantle. To investigate the controls on the chemistry of Brg, the Fe3+ content of Brg was investigated experimentally as a function of composition and oxygen fugacity (f o 2) at 25 GPa. The Fe3+/∑Fe ratio of Brg increases with Brg Al content and f o 2 and decreases with increasing total Fe content and with temperature. The dependence of the Fe3+/∑Fe ratio on f o 2 becomes less steep with increasing Al content. Thermodynamic models were calibrated to describe Brg and ferropericlase (Fp) compositions as well as the inter-site partitioning of trivalent cations in Brg in the Al–Mg–Si–O, Fe–Mg–Si–O and Fe–Al–Mg–Si–O systems. These models are based on equilibria involving Brg components where the equilibrium thermodynamic properties are the main adjustable parameters that are fit to the experimental data. The models reproduce the experimental data over wide ranges of f o 2 with a relatively small number of adjustable terms. Mineral compositions for plausible mantle bulk compositions can be calculated from the models as a function of f o 2 and can be extrapolated to higher pressures using data on the partial molar volumes of the Brg components. The results show that the exchange of Mg and total Fe (i.e., ferric and ferrous) between Brg and Fp is strongly f o 2 dependent, which allows the results of previous studies to be reinterpreted. For a pyrolite bulk composition with an upper mantle bulk oxygen content, the f o 2 at the top of the lower mantle is −0.86 log units below the iron–wüstite buffer (IW) with a Brg Fe3+/∑Fe ratio of 0.50 and a bulk rock ratio of 0.28. This requires the formation of 0.7 wt.% Fe–Ni alloy to balance the raised Brg ferric iron content. With increasing pressure, the model predicts a gradual increase in the Fe3+/∑Fe ratio in Brg in contrast to several previous studies, which levels off by 50 GPa. Oxygen vacancies in Brg decrease to practically zero by 40 GPa, potentially influencing elasticity, diffusivity and rheology in the top portion of the lower mantle. The models are also used to explore the f o 2 recorded by inclusions in diamonds, which likely crystallized as Brg in the lower mantle, revealing oxygen fugacities which likely preclude the formation of some diamonds directly from carbonates, at least at the top of the lower mantle. [ABSTRACT FROM AUTHOR]

BACKGROUND: Three lab‐scale sequencing batch reactors were used to investigate the effects of Fe3+ on aerobic granular sludge (AGS) formation, nutrient removal, and microbial community. RESULTS: The addition of 6 and 12 mg Fe3+ L−1 could not shorten the granulation time. However, compared to the reactor without Fe3+ addition (average sludge volume index at 30 min (SVI30) 70.8 mL g−1; stable average particle size 548 μm), the addition of 12 mg Fe3+ L−1 helped improve the physical properties of AGS (average SVI30 57.0 mL g−1; stable average particle size 1067 μm). Furthermore, with 12 mg Fe3+ L−1 addition (Fe3+ to PO43−‐P molar ratio = 1.33), effective removal of NH4+‐N (≤0.5 mg L−1) and PO43−‐P (<1 mg L−1) was achieved. The addition of Fe3+ reduced the microbial diversity and specific activity of heterotrophic bacteria, but promoted the growth of nitrite‐oxidizing bacteria. The growth of particle size not only increased the active biomass ratio and microbial diversity, but alleviated the inhibition effect of Fe3+ on the specific heterotrophic bacteria activity. CONCLUSION: The addition of Fe3+ had both negative and positive effects on the formation and stability of AGS. The results will help enrich the understanding of AGS application in nutrient removal and especially that of phosphorus. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Novel magnetic sodium alginate-based biopolymer Fe3O4@SA-Fe was successfully prepared by the cross-linking reaction of sodium alginate (SA) and Fe(III) ions and adding magnetic ferric oxide (Fe3O4), and characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), Fourier Transform-Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM), respectively. The effects of preparation and adsorption conditions on the adsorbent were investigated by adsorbing Congo red (CR) and Direct red 23 (DR 23) dyes. The results showed that the synthesized Fe3O4@SA-Fe polymer gel beads exhibited super-high adsorption property and good stability when the mass concentrations of SA, Fe(III) ions and Fe3O4 are 16, 12.5 and 7 g/L at room temperature respectively. The adsorption rates of two dyes by Fe3O4@SA-Fe were very fast at 298 K, and the time required to reach the equilibrium was very short, which was 30 min for CR and 60 min for DR 23. Moreover, the dye removal efficiencies were over 99.4% and 95.2% in a wide pH range of 2.0 ~ 9.0 for CR and 2.0 ~ 10.0 for DR 23, respectively. The adsorption process could be accurately described by the pseudo-second-order rate model, which were mostly controlled by intra-particle diffusion. The fitting results of isothermic data by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models revealed that the equilibrium data completely obeyed the Langmuir model and the obtained maximum adsorption capacities of CR and DR 23 were 3333 and 1429 mg/g at 298 K, respectively. FTIR, UV-Vis and XPS analysis indicated that the electrostatic adsorption, hydrogen bonding and ligand exchange promoted the interaction between dye molecules and Fe3O4@SA-Fe. A green magnetic biosorbent Fe3O4@SA-Fe gel beads with simple preparation method and high-cost performance can be used for super-efficient purification of high-concentration dye effluent and quickly separated from the aqueous phase and recovered, which would have a good application prospect. [ABSTRACT FROM AUTHOR]

This paper presents data for the assessment of a portable UV-Vis spectrophotometer's performance on predicting stream water DOC and Fe content. The dataset contains DOC and Fe concentrations by laboratory methods, in-situ and ex-situ spectral absorbances, monitoring environmental indexes such as water depth, temperature, turbidity and voltage. The records in Yli-Nuortti river (Cold station, Finland) took place during the hydrological year 2018-2019 and in Krycklan (C4 and C5, Sweden) during the hydrological years 2016-2019. The data analyses were conducted with ‘pls’ and ‘caret’ package in R. The correlation coefficient (R), root-mean-square deviation (RMSD), standard deviation (STD) and bias were used to check the performance of the models. This dataset can be combined with datasets from other regions around the world to build more universal models. For discussion and more information of the dataset creation, please refer to the full-length article “Assessment of a portable UV–Vis spectrophotometer's performance for stream water DOC and Fe content monitoring in remote areas” [1].

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.

The oxidation state of iron in upper mantle minerals is widely used to constrain the Earth mantle's oxidation state. Previous studies showed high levels of ferric iron in high-pressure majoritic garnets and pyroxenes despite reducing conditions. To disentangle the effects of pressure and increasing oxygen fugacity on the Fe3+/ΣFe ratios of garnet and clinopyroxene, we performed high-pressure experiments at a pressure of 10 GPa in a 1000-ton Walker-type multi-anvil apparatus at the University of Münster. We synthesized majoritic garnets and clinopyroxenes with a total iron content close to natural mantle values at different oxygen fugacities, ranging from IW+4.7 to metal saturation at IW+0.9. We analyzed the iron oxidation state in garnets with the electron microprobe "flank method." Furthermore, we investigated the oxidation state of iron in garnets and clinopyroxenes with transmission electron microscopy (TEM) electron energy loss spectroscopy (EELS). Although the flank method measurements are systematically lower than the EELS measurements, Fe3+/ΣFe obtained with both methods agree well within 2σ errors. The "flank method" has the advantage of being much faster and more easily to set up, whereas TEM-EELS has a much higher spatial resolution and can be applied to various non-cubic minerals such as orthopyroxenes and clinopyroxenes. We used our experimental results to compare two geobarometers that contain a term for ferric iron in garnet (Beyer and Frost 2017; Tao et al. 2018) with two geobarometers that do not account for ferric iron (Collerson et al. 2010; Wijbrans et al. 2016). We found that for garnets with low total Fe and Fe3+ (like many natural garnets), the pressures can be calculated without including the ferric iron content. [ABSTRACT FROM AUTHOR]