Homogeneous Iron Research Articles

Shifting to biology promotes highly efficient iron removal in groundwater filters

Rapid sand filters are established and widely applied technologies for groundwater treatment. In these filters, main groundwater contaminants such as iron, manganese, and ammonium are oxidized and removed. Conventionally, intensive aeration is employed to provide oxygen for these redox reactions. While effective, intensive aeration promotes flocculent iron removal, which results in iron oxide flocs that rapidly clog the filter. In this study, we operated two parallel full-scale sand filters at different aeration intensities to resolve the relative contribution of homogeneous, heterogeneous and biological iron removal pathways, and identify their operational controls. Our results show that mild aeration in the LOW filter (5 mg/L O2, pH 6.9) promoted biological iron removal and enabled iron oxidation at twice the rate compared to the intensively aerated HIGH filter (>10 mg/L O2, pH 7.4). Microscopy images showed distinctive twisted stalk-like iron solids, the biosignatures of Gallionella ferruginea, both in the LOW filter sand coatings as well as in its backwash solids. In accordance, 10 times higher DNA copy numbers of G. ferruginea were found in the LOW filter effluent. Clogging by biogenic iron solids was slower than by chemical iron flocs, resulting in lower backwash frequencies and yielding four times more water per run. Ultimately, our results reveal that biological iron oxidation can be actively controlled and favoured over competing physico-chemical routes. The production of more compact and practically valuable iron oxide solids is of outmost interest. We conclude that, although counterintuitive, slowing down iron oxidation in the water before filtration enables rapid iron removal in the biofilter.

Aerobic Oxidative Coupling of 2-Aminonaphthalenes by Homogenous Nonheme Iron Catalysts

Aerobic Oxidative Coupling of 2-Aminonaphthalenes by Homogenous Nonheme Iron Catalysts

Printability and Mechanical Properties of PLA/Iron Composites for FDM 3D Printing

Metal particle reinforcement plays an important role in the mechanical properties and printability of composite materials for FDM 3D-printing technology. PLA/Iron composite filament is widely used in many applications, such as magnetic and biomedical devices. This research aims to study the effect of iron particles on the printability and mechanical properties of PLA/Iron composite and compare it with another PLA composite of PLA/Stainless steel composite. The PLA/Iron (Fe) and PLA/Stainless steel (SS) composites were printed at different printing temperatures between 260-290 °C, printing speeds between 30-90 mm/s, and infill density of 100%. The max stress and elongation of printed PLA/Fe composite were higher than that of printed PLA/SS composite about 1.5 and 1.2 times. Moreover, the highest max stress of printed PLA/Fe composite specimens was 40.20 MPa at a printing temperature of 280 °C and printing speed of 60 mm/s. The optical microscope observed the homogeneous iron and stainless-steel particle distribution in PLA composite matrix and revealed the printed structure.

Effect of royal jelly on chronıc lıver and kıdney damage ınduced by cadmıum chlorıde ın rats

Forty eight rats were used to evaluate the protective effect of royal jelly (RJ) against chronic liver and kidney damage induced by cadmium chloride (CdCl2). In the histopathology of the CdCl2 group, the findings of inflammation and necrosis in liver sections, inflammation in kidney sections, proximal tubule degeneration and adiposity in the glomerulus were similar to the histopathological findings in the CdCl2 + RJ group. In immunohistochemical staining, it was determined that Caspase-3, Iba-1, KIM-1 and Tnf-a immunoreactivities in the liver and kidney tissue sections of the CdCl2-only group (Group III) were significantly increased compared to the control groups (Groups I, II). In the CdCl2 + RJ applied group (Group IV), Caspase-3, Iba-1, KIM-1 and TNF-α immunoreactivities were observed to be partially reduced compared to the CdCl2 (Group III) group. It was determined that AST, ALT, glucose, triglyceride, cholesterol and creatinine levels increased in the CdCl2 group and decreased in the CdCl2 + RJ group. While MDA levels increased in the group given only CdCl2 (Group III) compared to the control groups (Groups I, II), GSH levels decreased. In the CdCl2 + RJ group (Group IV), it was determined that MDA levels decreased and GSH levels increased compared to the CdCl2 (Group III) group. While the amounts of cadmium, zinc, copper, iron, magnesium and calcium in the liver tissue homogenates increased significantly in the CdCl2 group, it was observed that they decreased numerically in the CdCl2 + RJ group. This result shows that royal jelly application against CdCl2 toxicity does not prevent liver and kidney tissue damage, but can bring serum biochemical parameters, lipid peroxidation and trace element levels closer to control group levels.

Biodiesel from Waste Cooking Oil: Highly Efficient Homogeneous Iron(III) Molecular Catalysts

This article presents an efficient iron(III) molecular catalyst for the production of biodiesel from waste vegetable oils. The approach involved an initial screening of eight salophen complexes with various substituents on the arene rings, leading to the selection of the simplest unsubstituted species as the most active catalyst. Under optimized conditions, this catalyst demonstrated the capability to achieve complete conversion of the oil at a low catalyst loading (0.10% mol/mol) and convenient conditions (160 °C, 20/1 MeOH/oil ratio).

Formation of Red Elemental Selenium from Seleniferous Oxyanions: Deoxygenation by a Homogeneous Iron Catalyst.

Seleniferous oxyanions are groundwater contaminants from both anthropogenic and natural sources, while pure amorphous selenium nanoparticles have a variety of industrial applications. Biology can achieve the multicomponent 6 e-/8 H+ reduction of selenate to amorphous selenium using multiple metalloenzymes, like selenate and selenite reductase. Inspired by biology, we developed a new homogeneous system that can generate pure elemental selenium with no caustic waste. The stoichiometric reductions of selenate, selenite, and selenium dioxide with an iron(II) complex produced an iron(III)-oxo and red elemental selenium, the latter of which has been characterized by a variety of spectroscopic techniques. The catalytic reduction of SeO42- and SeO32- directly to amorphous Se and isolated as Se=PPh3 is reported with a turnover number of 12 and 7, respectively.

Possibilities and Limitations of the Sono-Fenton Process Using Mid-High-Frequency Ultrasound for the Degradation of Organic Pollutants.

Mid-high-frequency ultrasound (200-1000 kHz) eliminates organic pollutants and also generates H2O2. To take advantage of H2O2, iron species can be added, generating a hybrid sono-Fenton process (sF). This paper presents the possibilities and limitations of sF. Heterogeneous (a natural mineral) and homogeneous (Fe2+ and Fe3+ ions) iron sources were considered. Acetaminophen, ciprofloxacin, and methyl orange were the target organic pollutants. Ultrasound alone induced the pollutants degradation, and the dual competing role of the natural mineral (0.02-0.20 g L-1) meant that it had no significant effects on the elimination of pollutants. In contrast, both Fe2+ and Fe3+ ions enhanced the pollutants' degradation, and the elimination using Fe2+ was better because of its higher reactivity toward H2O2. However, the enhancement decreased at high Fe2+ concentrations (e.g., 5 mg L-1) because of scavenger effects. The Fe2+ addition significantly accelerated the elimination of acetaminophen and methyl orange. For ciprofloxacin, at short treatment times, the degradation was enhanced, but the pollutant complexation with Fe3+ that came from the Fenton reaction caused degradation to stop. Additionally, sF did not decrease the antimicrobial activity associated with ciprofloxacin, whereas ultrasound alone did. Therefore, the chemical structure of the pollutant plays a crucial role in the feasibility of the sF process.

Relationship Between Iron Distribution in Deep Gray Matter Nuclei Measured by Quantitative Susceptibility Mapping and Motor Outcome After Deep Brain Stimulation in Patients With Parkinson's Disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor deficits in advanced Parkinson's disease (PD) patients, but the degree of motor improvement varies across individuals. PD pathology involves the changes of iron spatial distribution in the deep gray matter nuclei. To explore the relationship between the iron spatial distribution and motor improvement among PD patients who underwent STN-DBS surgery in three regions: substantia nigra (SN), STN, and dentate nucleus (DN). Prospective. Forty PD patients (49.7 ± 8.8 years, 22 males/18 females) who underwent bilateral STN-DBS. A 3 T preoperative three-dimensional spoiled bipolar-readout multi-echo gradient recalled echo and two-dimensional fast spin echo sequences. Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III) scores were assessed 2-3 days before and 6 months after STN-DBS. The first- and second-order texture features in regions of interest were measured on susceptibility maps. Intraclass correlation coefficient was used to determine the consistency of the region of interest volumes delineated by the two raters. Pearson or Spearman's correlation coefficients were used to assess the relationship between motor improvement after DBS and texture features. A P-value <0.05 was considered statistically significant. MDS-UPDRS III scores were reduced by 59.9% after STN-DBS in 40 PD patients. Motor improvement correlated with second-order texture parameters in the SN including angular second moment (r=-0.449), correlation (rho=0.326), sum of squares (r=0.402), sum of entropy (rho=0.421), and entropy (r=0.410). Additionally, DBS outcome negatively correlated with mean susceptibility values in the DN (r=-0.400). PD patients with a more homogeneous iron distribution throughout the SN or a higher iron concentration in the DN responded worse to STN-DBS. 2 TECHNICAL EFFICACY: Stage 1.

Applying green chemistry principles to iron catalysis: mild and selective domino synthesis of pyrroles from nitroarenes.

An efficient and general cascade synthesis of pyrroles from nitroarenes using an acid-tolerant homogeneous iron catalyst is presented. Initial (transfer) hydrogenation using the commercially available iron-Tetraphos catalyst is followed by acid catalysed Paal-Knorr condensation. Both formic acid and molecular hydrogen can be used as green reductants in this process. Particularly, under transfer hydrogenation conditions, the homogeneous catalyst shows remarkable reactivity at low temperatures, high functional group tolerance and excellent chemoselectivity transforming a wide variety of substrates. Compared to classical heterogeneous catalysts, this system presents complementing reactivity, showing none of the typical side reactions such as dehalogenation, debenzylation, arene or olefin hydrogenation. It thereby enhances the chemical toolbox in terms of orthogonal reactivity. The methodology was successfully applied to the late-stage modification of multi-functional drug(-like) molecules as well as to the one-pot synthesis of the bioactive agent BM-635.

Nonmonotonic Superparamagnetic Behavior of the Ferritin Iron Core Revealed via Quantum Spin Relaxometry

Ferritin is the primary storage protein in our body and is of significant interest in biochemistry, nanotechnology, and condensed matter physics. More specifically within this sphere of interest are the magnetic properties of the iron core of ferritin, which have been utilized as a contrast agent in applications such as magnetic resonance imaging. This magnetism depends on both the number of iron atoms present, L, and the nature of the magnetic ordering of their electron spins. In this work, we create a series of ferritin samples containing homogeneous iron loads and apply diamond-based quantum spin relaxometry to systematically study their room temperature magnetic properties. We observe anomalous magnetic behavior that can be explained using a theoretical model detailing a morphological change to the iron core occurring at relatively low iron loads. This model provides an L0.35±0.06 scaling of the uncompensated Fe spins, in agreement with previous theoretical predictions. The necessary inclusion of this morphological change within the model is also supported by electron microscopy studies of ferritin with low iron content. This provides evidence for a magnetic consequence of this morphological change and positions diamond-based quantum spin relaxometry as an effective, noninvasive tool for probing the magnetic properties of metalloproteins. The low detection limit (ferritin 2% loaded at a concentration of 7.5 ± 0.4 μg/mL) also makes this a promising method for precision applications where low analyte concentrations are unavoidable, such as in biological research or even clinical analysis.

Homogeneous ferrous iron oxidation in a pilot-scale electrocoagulation system treating municipal wastewater: a model validation and simulation study.

During an iron-electrocoagulation (Fe-EC) process, floc formation is essential for achieving high contaminants removal. Thus, the complete oxidation of the Fe2+ dosed as coagulant is a critical step for ferric oxides flocs formation. Since the fluctuation in the quality of the influent wastewater affects the kinetics of Fe2+ oxidation, the estimation of optimal operating conditions (i.e. the retention time, dissolved oxygen (DO) concentration, etc.) for high Fe2+ oxidation is required. In this study, the kinetics of Fe2+ oxidation was simulated using PHREEQC software by theoretically optimizing, validating and improving the previously published kinetic models. During model simulation, the process parameters were varied from low to high ranges: Fe2+ dosage (10-100 mg/L) and retention times under the influence of changing pH (7.5-8.2), temperature (12-22 °C), alkalinity (5-10 mEq/L) and initial DO (8.6-10.5 mg/L). Fe2+ oxidation rate was more affected by pH variations in the influent than by temperature variations. A pH increase (+0.4 to +1.7 pH units) was observed due to the low wastewater alkalinity, promoting high Fe2+ oxidation rates. To ensure optimum Fe2+ oxidation levels (≥98%), a minimum retention time of 20 minutes was estimated. Finally, the residual DO concentration should be >3.5 mg/L to avoid a decrease in the oxidation rate. This study contributes to the ongoing research in the field of physico-chemical wastewater treatment with EC by establishing the optimal process parameters required for system optimization and process scalability.

In-situ alloying of Ti-5Fe titanium alloy using direct powder forging and the effect of the powder mixing method

This study investigates direct powder forging (DPF) as a new approach for the consolidation and in-situ alloying of the titanium alloy Ti-5Fe from loose powder. The absence of green compaction before thermomechanical processing and the effect of the powder blending method have been found to significantly influence the chemical and microstructure homogeneity. Two different powder mixing techniques were compared, ball milling (BM) and blended elemental (BE). After the initial heating stage, the BM sample has a uniform α+β lamella microstructure within the particles with a homogeneous iron distribution, unlike the BE sample, which shows a heterogeneous lamella microstructure, retained β-Ti (Fe-rich) and TiFe intermetallic compounds. Even if the BM samples exhibit a slightly higher density over the BE samples after the initial heating stage, all samples achieved full density and had a α+β lamella microstructure after the thermomechanical steps. However, for the BE sample, even if the DPF process was able to eliminate the intermetallic compounds, the thermomechanical process did not homogenize the iron, resulting in a heterogeneous and coarser microstructure. Based on the results, it can be concluded that DPF using a BM technique led to a fully homogenous and fully consolidated Ti-5Fe alloy. Therefore, direct powder forging has significant potential as an alternative fabrication strategy to produce the Ti-5Fe alloy. Moreover, this work can expand the opportunities for the development of the promising Ti-5Fe alloy.

Stellar population astrophysics (SPA) with the TNG

Context. The Perseus complex in the outer disk of the Galaxy hosts a number of clusters and associations of young stars. Gaia is providing a detailed characterization of their kinematic structure and evolutionary properties. Aims. Within the SPA Large Program at the TNG, we secured HARPS-N and GIANO-B high-resolution optical and near-infrared (NIR) spectra of the young red supergiant (RSG) stars in the Perseus complex in order to obtain accurate radial velocities, stellar parameters, and detailed chemical abundances. Methods. We used spectral synthesis to best fit hundreds of atomic and molecular lines in the spectra of the observed 27 RSGs. We obtained accurate estimates of the stellar temperature, gravity, micro- and macroturbulence velocities, and chemical abundances for 25 different elements. We also measured the 12C/13C abundance ratio. Results. Our combined optical and NIR chemical study provides homogeneous half-solar iron with a low dispersion, about solar-scaled abundance ratios for the iron-peak, alpha-, and other light elements, and a low enhancement of Na, K, and neutron-capture elements. This is consistent with the thin-disk chemistry traced by older stellar populations at a similar galactocentric distance of about 10 kpc. We inferred an enhancement of N and a depletion of C and of the 12C/13C isotopic abundance ratio that are consistent with mixing processes in the stellar interiors during the RSG evolution.

Constraining the original composition of the gas forming first-generation stars in globular clusters

ABSTRACT Disentangling distinct stellar populations along the red-giant branches (RGBs) of globular clusters (GCs) is possible by using the pseudo-two-colour diagram dubbed chromosome map (ChM). One of the most intriguing findings is that the so-called first-generation (1G) stars, characterized by the same chemical composition of their natal cloud, exhibit extended sequences in the ChM. Unresolved binaries and internal variations in helium or metallicity have been suggested to explain this phenomenon. Here, we derive high-precision Hubble Space Telescope photometry of the GCs NGC 6362 and NGC 6838 and build their ChMs. We find that both 1G RGB and main-sequence (MS) stars exhibit wider ChM sequences than those of second-generation (2G). The evidence of this feature even among unevolved 1G MS stars indicates that chemical inhomogeneities are imprinted in the original gas. We introduce a pseudo-two-magnitude diagram to distinguish between helium and metallicity, and demonstrate that star-to-star metallicity variations are responsible for the extended 1G sequence. Conversely, binaries provide a minor contribution to the phenomenon. We estimate that the metallicity variations within 1G stars of 55 GCs range from less than [Fe/H]∼0.05 to ∼0.30 and mildly correlate with cluster mass. We exploit these findings to constrain the formation scenarios of multiple populations showing that they are qualitatively consistent with the occurrence of multiple generations. In contrast, the fact that 2G stars have more homogeneous iron content than the 1G challenges the scenarios based on accretion of material processed in massive 1G stars on to existing protostars.

Constructive Improvements in the In-Ladle Treatments

Nodular gray cast iron having properties superior to conventional gray cast iron can be produced by treating the molten iron so that, when cast, the graphite will be compacted rather than in flake form. One such treatment involves the introduction of magnesium (Mg) into a molten iron bath of such composition. It is the principal object of the present industrial experiments to provide an improved process for the ductile cast iron production. Another object is to provide a process which permits the efficient use of the nodulizing agents, which results in the efficient production of an improved homogeneous nodular cast iron. Essentially such treatments result in the retention by the cast iron of small amounts of nodulizing agents, for example magnesium (Mg). Conventionally these agents are added to cast iron, usually in the form of pre-alloys and the efficiency of the process is illustrated by the high assimilation of the added nodulizer’s constituents. Another object of this technological practice is to provide an improved method for introducing the nodulizing agents, using constructive improvements to the in-ladle equipment. Finding magnesium (Mg) using novel techniques is the first step to advance the understanding of the role of magnesium (Mg) in the formation of the nodular graphite, the mechanism behind nodular graphite formation due to the addition of Magnesium (Mg) being still relative unclear at present time. Moreover, this may advance new methods to improve the nodulizing treatment process. This study take into account the flexibility of the used technique, which describes the elasticity of the treatment process, by improvement or alternative to the existing one. As nodulizing agents magnesium-ferrosilicon (Fe-Si-Mg type) and cerium-magnesium-ferrosilicon (Nodulin type) are examples of materials containing nodulizing agents that have given excellent results in the mixture. This experiments relates to a process for the production of ductile iron (nodular gray cast iron) and particularly to a process for adding magnesium (Mg) to the melted iron.

Synthesis features, structure, magnetometry and NMR spectroscopy of nanowires of various types

Various types of nanowires obtained by matrix synthesis --- homogeneous (from iron) and heterogeneous (layered) --- have been studied. A technique for obtaining arrays of layered nanowires with alternating thin layers of magnetic and non-magnetic metals (Co/Cu, Ni/Cu) has been developed and described. Microscopy methods (SEM and TEM with elemental analysis) have been used to study the topography of the resulting structures, the diameters of nanowires and the thicknesses of individual layers, and the features of interlayer interfaces. Methods of synthesis of nanowires with thin layers and clear boundaries are proposed --- dilution of the electrolyte, use of a reference electrode, control of the leaked charge. Layered nanowires have been studied by magnetometry methods and it has been shown that the magnetic properties of an array of layered nanowires (in particular, the direction of the axis of light magnetization in the Co/Cu-NP array) depend not only on the aspect ratio of the magnetic layer, but also on the ratio of the thickness of the magnetic metal layer to the thickness of a non-magnetic spacer (copper layer). The nuclear magnetic resonance (NMR) method was used to study two types of nanowires. The NMR method (on 59-Co nuclei) studied the layer structures of Co/Cu: it is shown that in nanowires with layers of smaller thickness (and, accordingly, with a large contribution of interfaces), a large proportion of Co atoms coordinated by Cu atoms is observed. The high proportion of atoms coordinated by copper suggests that an admixture of copper enters the cobalt layers. Homogeneous iron nanowires (NMR on 57-Fe nuclei) were compared with bulk iron samples. A shift of the line towards high frequencies (by 0.3 MHz) was detected, indicating an increase in the field by about 0.2 T. A significant broadening of the line and a decrease in the spin-lattice relaxation time may indicate a significant variation in the local magnetic field values. Keywords: nanowires, matrix synthesis, microscopy, elemental analysis, magnetic properties, NMR.

Iron-catalyzed domino coupling reactions of π-systems.

The development of environmentally benign, inexpensive, and earth-abundant metal catalysts is desirable from both an ecological and economic standpoint. Certainly, in the past couple decades, iron has become a key player in the development of sustainable coupling chemistry and has become an indispensable tool in organic synthesis. Over the last ten years, organic chemistry has witnessed substantial improvements in efficient synthesis because of domino reactions. These protocols are more atom-economic, produce less waste, and demand less time compared to a classical stepwise reaction. Although iron-catalyzed domino reactions require a mindset that differs from the more routine noble-metal, homogenous iron catalysis they bear the chance to enable coupling reactions that rival that of noble-metal-catalysis. This review provides an overview of iron-catalyzed domino coupling reactions of π-systems. The classifications and reactivity paradigms examined should assist readers and provide guidance for the design of novel domino reactions.

Fabricating iron wires with superior strength–ductility combination through a gradient lamellar structure

A gradient lamellar structure iron wire (GLS-IW) was fabricated by pre-torsion and severe cold-drawing. Compared to the homogenous lamellar structure iron wire (HLS-IW) produced by single cold-drawing, the tensile strength of GLS-IW was increased by 35% and the uniform elongation was tripled. GLS-IW exhibits decreasing lamellar thickness and increasing high angle grain boundaries (HAGBs) from center-layer to surface-layer. The reasons for good mechanical properties were discussed.

Bringing Homogeneous Iron Catalysts on the Heterogeneous Side: Solutions for Immobilization.

Noble metal catalysts currently dominate the landscape of chemical synthesis, but cheaper and less toxic derivatives are recently emerging as more sustainable solutions. Iron is among the possible alternative metals due to its biocompatibility and exceptional versatility. Nowadays, iron catalysts work essentially in homogeneous conditions, while heterogeneous catalysts would be better performing and more desirable systems for a broad industrial application. In this review, approaches for heterogenization of iron catalysts reported in the literature within the last two decades are summarized, and utility and critical points are discussed. The immobilization on silica of bis(arylimine)pyridyl iron complexes, good catalysts in the polymerization of olefins, is the first useful heterogeneous strategy described. Microporous molecular sieves also proved to be good iron catalyst carriers, able to provide confined geometries where olefin polymerization can occur. Same immobilizing supports (e.g., MCM-41 and MCM-48) are suitable for anchoring iron-based catalysts for styrene, cyclohexene and cyclohexane oxidation. Another excellent example is the anchoring to a Merrifield resin of an FeII-anthranilic acid complex, active in the catalytic reaction of urea with alcohols and amines for the synthesis of carbamates and N-substituted ureas, respectively. A SILP (Supported Ionic Liquid Phase) catalytic system has been successfully employed for the heterogenization of a chemoselective iron catalyst active in aldehyde hydrogenation. Finally, FeIII ions supported on polyvinylpyridine grafted chitosan made a useful heterogeneous catalytic system for C–H bond activation.

Single Atomic Iron Site Catalysts via Benign Aqueous Synthesis for Durability Improvement in Proton Exchange Membrane Fuel Cells

Atomically-dispersed iron-nitrogen-carbon (Fe–N–C) catalysts have arisen as promising candidates for replacing the costly precious metal catalysts in fuel cells but still face some grand challenges, such as insufficient site density and durability. Herein, we report a self-assembly method in an aqueous solution to develop an atomically-dispersed iron catalyst with high oxygen reduction reaction (ORR) activity and stability in acidic electrolytes. As determined by high-resolution transmission electron microscopy (HR-TEM), X-ray absorption spectroscopy (XAS), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), this benign aqueous synthesis strategy facilitates the formation of homogeneous atomic nitrogen-coordinated iron sites embedded in a popcorn-like porous graphitic carbon matrix. These catalyst properties contribute to the improved ORR kinetic current density and mass transport. By controlling synthesis chemistry, the correlation between structure and property is systematically investigated. The iron content is the most critical material property and can regulate site density and graphitic carbon structures in the catalyst, impacting catalytic activity and stability. The enhanced performance and durability were examined in both acidic aqueous electrolytes and membrane electrode assemblies.