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[Display omitted] Macrophages are known to depict two major phenotypes: classically activated macrophages (M1), associated with high production of pro-inflammatory cytokines, and alternatively activated macrophages (M2), which present an anti-inflammatory function. A precise control over M1-M2 polarization is a promising strategy in therapeutics to modulate both tissue regeneration and tumor progression processes. However, this is not a simple task as macrophages behave differently depending on the microenvironment. In agreement with this, non-consistent data have been reported regarding macrophages response to magnetic iron oxide nanoparticles (MNPs). To investigate the impact of both tissue microenvironment and MNPs properties on the obtained macrophage responses, single-core (SC) and multi-core (MC) citrate coated MNPs, are synthesized and, afterwards, loaded with a macrophage polarization trigger, IL-4. The developed MNPs are then tested in macrophages subjected to different stimuli. We demonstrate that macrophages treated with low concentrations of MNPs behave differently depending on the polarization stage independently of the concentration of iron. Moreover, we find out that MNPs size and morphology determines the effect of the IL-4 loaded MNPs on M1 macrophages, since IL-4 loaded SC MNPs favor the polarization of M1 macrophages towards M2 phenotype, while IL-4 loaded MC MNPs further stimulate the secretion of pro-inflammatory cytokines. [ABSTRACT FROM AUTHOR]

[Display omitted] This study presents a comprehensive community data-driven surface complexation modeling framework for simulating potentiometric titration of mineral surfaces. Compiled community data for ferrihydrite, goethite, hematite, and magnetite are fit to produce representative protolysis constants that can reproduce potentiometric titration data collected from multiple literature sources. Using this framework, the impact of surface complexation model type and surface site density (SSD) on the fit quality and protolysis constants can be readily evaluated. For example, the non-electrostatic model yielded a poor data fit compared to diffuse double layer model and constant capacitance models due to the absence of known surface charge effects. Regardless of the choice of iron oxide mineral, pK a1 decreased with increasing SSD while the opposite tendency was observed for pK a2. This newly developed framework demonstrates a method to reconcile community data-wide potentiometric titration data using Findable, Accessible, Interoperable, Reusable data principles to produce mineral protolysis constants that improve robustness of surface complexation models for applications in metal sorption and reactive transport modeling. The framework is readily expandable (as community data increase) and extensible (as the number of minerals increase). The framework provides a path forward for developing self-consistent, comprehensive, and updateable surface complexation databases for surface complexation and reactive transport modeling. [ABSTRACT FROM AUTHOR]

Yolk-shell porous Fe 3 O 4 @C anchored on graphene nanosheets (Y-S-P-Fe 3 O 4 /GNs@C) with fast electron/ion transport channels, exhibits excellent rate capability and cycling stability. The assembled Y-S-P-Fe 3 O 4 /GNs@C//LiFePO 4 full-cell delivers a high energy density of 341.0 Wh kg−1 at 37.9 W kg−1. [Display omitted] Iron oxides have been widely studied as anode materials for lithium-ion batteries (LIBs) due to their high conductivity (5 × 104 S m−1) and high capacity (ca. 926 mAh g−1). However, having a large volume change and being highly prone to dissolution/aggregation during charge/discharge cycles hinder their practical application. Herein, we report a design strategy for constructing yolk-shell porous Fe 3 O 4 @C anchored on graphene nanosheets (Y-S-P-Fe 3 O 4 /GNs@C). This particular structure can not only introduce sufficient internal void space to accommodate the volume change of Fe 3 O 4 but also afford a carbon shell to restrict Fe 3 O 4 overexpansion, thus greatly improving capacity retention. In addition, the pores in Fe 3 O 4 can effectively promote ion transport, and the carbon shell anchored on graphene nanosheets is capable of enhancing overall conductivity. Consequently, Y-S-P-Fe 3 O 4 /GNs@C features a high reversible capacity of 1143 mAh g−1, an excellent rate capacity (358 mAh g−1 at 10.0 A g−1), and a prolonged cycle life with robust cycling stability (579 mAh g−1 remaining after 1800 cycles at 2.0 A g−1) when assembled into LIBs. The assembled Y-S-P-Fe 3 O 4 /GNs@C//LiFePO 4 full-cell delivers a high energy density of 341.0 Wh kg−1 at 37.9 W kg−1. The Y-S-P-Fe 3 O 4 /GNs@C is proved to be an efficient Fe 3 O 4 -based anode material for LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] The pseudocapacitive metal oxide anchored nanocarbon-based three-dimensional (3D) materials are considered attractive electrode materials for high-performance supercapacitor applications. However, the complex multistep synthesis approaches raise production costs and act as a major barrier to the practical real-world field. To overcome this limitation, in this study, an easily scalable and effective fabrication approach for the development of iron oxide (Fe 3 O 4) anchored highly porous carbon nanotube hybrid foam (f- Fe 3 O 4 /O-CNTF) with micro/mesoporous structure was suggested to improve the durability and energy storage performance. The surface morphology-tuned f -Fe 3 O 4 /O-CNTF (f -Fe 3 O 4 /O-CNTF(M)) was fabricated through electromagnetic interaction between the anchored magnetic Fe 3 O 4 on the CNT surface and the applied magnetic field. The obtained results clearly demonstrated that the changed surface morphology of the f -Fe 3 O 4 /O-CNTF(M) strongly affected the meso- and micropore structure, electrochemical performance, and durability. Consequently, the f -Fe 3 O 4 /O-CNTF(M) showed an almost 120% enhanced specific surface area and nearly 1.9 times increased specific capacitance compared to that of the f -Fe 3 O 4 /O-CNTF. Furthermore, the changed surface morphology successfully prevented the re-aggregation of the initial structure and significantly improved durability. As a result, f -Fe 3 O 4 /O-CNTF(M) showed outstanding cycling stability, maintaining almost 100% capacitance retention after 14,000 cycles. Consequently, the assembled symmetric supercapacitor device delivered an energy density of 20.1 Wh·kg−1 at a power density of 0.37 kW·kg−1 with good cycling stability. These results suggest that the f -Fe 3 O 4 /O-CNTF(M) can potentially be used as an electrode for supercapacitors with good durability. [ABSTRACT FROM AUTHOR]

Compared with defect-free FeO x , the ultrafine FeO x in the FeO x (0.03)@HG-110 with abundant surface defects shows lower energy barrier and higher OER activity. [Display omitted] • The FeO x (0.03)@HG-110 exhibits an OER overpotential as low as 342 mV at 10 mA cm−2. • The average particle size of FeOx is ca. 1.6 nm. • FeO x (0.03)@HG-110 possesses a low E a of 35.9 kJ mol−1. • The rate-determining step is *O → *OOH with the energy barriers of 0.79 eV. Development of earth-abundant and robust oxygen evolution reaction (OER) catalysts is imperative for cost-effective hydrogen production via water electrolysis. Herein, we report ultrafine iron (oxy)hydroxide nanoparticles with average particle size of 2.6 nm and abundant surface defects homogeneously supported on oleum-treated graphite (FeO x (n)@HG-T), providing abundant active sites for the OER. The optimal FeO x (0.03)@HG-110 exhibits high electrocatalytic OER activity and excellent stability. Electrochemical testing results and theoretical calculations reveal that the outstanding OER activity of FeO x (0.03)@HG-110 is due to its stronger charge transfer ability and lower OER energy barrier than defect-free FeO x nanoparticles. This work demonstrates that the OER performance of oxyhydroxide-based electrocatalysts can be improved by surface defect engineering. [ABSTRACT FROM AUTHOR]

Hematite nanoparticles commonly undergoes isomorphic substitution of Al3+ in nature, while how the Al-substitution-induced morphological change, defective structure and newly generated Al–OH sites affect the adsorption behavior of hematite for contaminants remains poorly understood. Herein, the interfacial reactions between Al-substituted hematite and Pb2+ was investigated via CD-MUSIC modeling and DFT calculations. As the Al content increased from 0% to 9.4%, Al-substitution promoted the proportion of (001) facets and caused Fe vacancies on hematite, which increased the total active site density of hematite from 5.60 to 17.60 sites/nm2. The surface positive charge of hematite significantly increased from 0.096 to 0.418 C/m2 at pH 5.0 due to the increases in site density and proton affinity (log K H) of hematite under Al-substitution. The adsorption amount of hematite for Pb2+ increased from 3.92 to 9.74 mmol/kg at pH 5.0 and 20 μmol/L initial Pb2+ concentration with increasing Al content. More Fe vacancies may lead to a weaker adsorption energy (E ad) of hematite for Pb2+, while the E ad was enhanced at higher Al content. The adsorption affinity (log K Pb) of bidentate Pb complexes slightly increased while that of tridentate Pb complexes decreased with increasing Al content due to the presence of ≡ AlOH−0.5 and ≡ Fe 2 AlO−0.5 sites. Tridentate Pb complexes were dominant species on the surface of pure hematite, while bidentate ones became more dominant with increasing Al content. The obtained model parameters and molecular scale information are of great importance for better describing and predicting the environmental fate of toxic heavy metals in terrestrial and aquatic environments. [Display omitted] • Adsorption of Al-hematite for Pb2+ was studied via CD-MUSIC and DFT calculation. • Al-substitution increased total active site density of hematite from 5.60 to 17.60 sites/nm2. • Al-substitution in hematite enhance its surface charge and Pb2+ adsorption. • Presence of ≡ AlOH−0.5 and ≡ Fe 2 AlO−0.5 sites altered the log K Pb and E ads of Pb2+ on hematite. • Bidentate Pb complexes became more dominant on hematite with increasing Al content. [ABSTRACT FROM AUTHOR]

Pesticides can have harmful impacts on the environment and living organisms. Thus, removing them from polluted water is crucial. In this study, a bionanocomposite of carboxymethyl tragacanth- grafted -poly(3-aminophenol)/zinc oxide@iron oxide (CMT- g -P3AP/ZnO@Fe 3 O 4) synthesized by in situ copolymerization as an efficient adsorbent to eliminate the acetamiprid pesticide from polluted water. The CMT- g -P3AP/ZnO@Fe 3 O 4 magnetic nanocomposite was analyzed utilizing various techniques including FTIR, EDX, FESEM, XRD, BET, CHNSO, and TGA. The results displayed that the resulting nanocomposite with maximum adsorption capacity (Q max) successfully removed the acetamiprid pesticide from polluted water under optimal conditions such as pH of 7.00, 5.00 mg of adsorbent, 20.0 min duration, and 400 mg/L acetamiprid concentration. According to the linear Langmuir isotherm, the Q max of the biosorbent was 833 mg/g. The experimental adsorption data fitted well with Temkin's nonlinear isotherm model. The adsorption kinetic data were closely related to the Weber-Morris intraparticle diffusion nonlinear model. After three repetitive cycles, CMT- g -P3AP/ZnO@Fe 3 O 4 can be outstandingly renewed and recycled without significant reduction in its adsorption efficacy, as evidenced by the adsorption-desorption experiments. In addition, the CMT-g-P3AP/ZnO@Fe 3 O 4 displayed the good antibacterial activity against E. coli and S. aureus. [Display omitted] • Antibacterial magnetic bionanocomposite based on carboxymethyl tragacanth synthesized. • Antibacterial magnetic bionanocomposite used as a sorbent for acetamiprid removal. • Maximum adsorption capacity of the bionanocomposite for acetamiprid was 833 mg/g. • Bionanocomposite showed good antibacterial activity against E. coli and S. aureus. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stronger Fe-Al interactions decrease FeC x /FeO x ratio but increase Fe 5 C 2 /Fe 7 C 3 ratio. • High content of FeC x is benefit for improving CO 2 hydrogenation activity. • Fe 5 C 2 is more favorable for the formation of heavy hydrocarbons than Fe 7 C 3. • Fe 7 C 3 phase is partially transformed into Fe 5 C 2 during CO 2 hydrogenation. Different iron species exhibit distinct activity and selectivity in CO 2 hydrogenation reaction. Herein, by controlling calcination temperature, Fe-Al interaction in Na promoted Fe-Al catalysts has been regulated, which further leads to various compositions of iron oxide (FeO x) and iron carbides (Fe 7 C 3 and Fe 5 C 2) after CO activation and CO 2 hydrogenation reaction. The phase compositions and structures of Fe-Al catalysts are carefully distinguished by multiple characterizations, including XRD, XPS, MES and TEM, and the reactivity of different phases is studied with the combination of experiments (kinetics, TP and in situ DRIFTS) and Density Functional Theory (DFT) calculations. Our FeAl350 with the highest FeC x content shows the highest CO 2 conversion of 48.2% and the lowest CO selectivity of 10.1%, and FeAl900 with the highest Fe 5 C 2 / FeC x ratio presents the highest C 5+ selectivity of 44.6%. Finally, a correlation between different compositions of iron species with the activity and selectivity of Fe-based for CO 2 hydrogenation to olefins was established. [ABSTRACT FROM AUTHOR]

The surface chemistry of monoethanolamine (MEA) on oxide surfaces is investigated by Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy under different environmental conditions of pH, concentration, and ionic strength. [Display omitted] Chemical contaminants are becoming an increasingly greater concern for water quality and it is well known that interactions with geochemical interfaces impact the fate and transport of these contaminants in the environment. In this study, we investigated the interactions of one such chemical contaminant, monoethanolamine (MEA), with oxide surfaces, particularly titanium dioxide (TiO 2) and iron oxide (α-Fe 2 O 3). Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy was used to probe the adsorption behavior of MEA on titanium dioxide (TiO 2) and iron oxide (α-Fe 2 O 3) nanoparticles as a function of pH and other environmental conditions including concentration and ionic strength. Both the extent and initial rates of adsorption of MEA on these oxide surfaces increases with increasing pH. Adsorption on these oxide surfaces increases with solution concentration until saturation occurs and MEA adsorbs more readily at higher pH. Furthermore, adsorption decreases with increasing ionic strength, demonstrating the importance of electrostatic interactions to this process. Based on these results, a mechanistic picture emerges for the interaction of MEA with titanium dioxide and iron oxide across a range of pH values. Overall, this study provides important insights into the surface chemistry and interactions between an alkanolamine and geochemical oxide interfaces. [ABSTRACT FROM AUTHOR]

The development of biocompatible adsorbents is vital for environmental remediation to control and reduce pollution and waste accumulation in ecosystems. Biocompatible hydrogels represent an innovative class of materials that are primarily composed of polymer chain units forming their structural framework. They have a high affinity for water molecules. This research thus aims to incorporate iron oxide particles into the gelatin matrix to produce gelatin hydrogel beads to remove hexavalent chromium from an aqueous solution. The synthesized beads, known for their consistent size, low friction, high specific surface area, mechanical stability, and lightweight characteristics, demonstrated their suitability for various industrial applications. The effectiveness of these hydrogels in removing hexavalent chromium ions was confirmed through a thorough analysis using techniques such as FTIR, TGA, SEM, EDX, VSM, and XPS. Batch experiments revealed that the gelatin-based nanocomposite beads exhibited optimal adsorption efficiency under acidic conditions, lower initial concentrations of chromium ions, extended contact time, and elevated temperature (50–60 °C). The composite achieved a maximum removal efficiency of 99% at pH 1, with an adsorbent dose of 0.5 g at 50 °C, and an initial concentration of 50 mg per liter. The use of 0.7 N NaOH in the regeneration process resulted in a commendable 70.5% desorption efficiency, enabling potential reuse and regeneration. Significantly, the desorption efficiency remained consistently high even after four desorption-readsorption cycles, contributing to the economic and environmental sustainability of chromium removal. Additionally, the study determined that the sorption process was feasible, spontaneous, and endothermic. These collective findings suggest that magnetic gelatin hydrogel beads could serve as a cost-effective alternative adsorbent for the efficient removal of chromium ions from aqueous solutions. • Synthesized gelatin hydrogel beads for the removal of hexavalent chromium from aqueous solution. • Gelatin-based nanocomposite beads exhibited optimal adsorption efficiency under acidic conditions. • 0.7 N NaOH in the regeneration process resulted in a commendable 70.5% desorption efficiency. • Desorption efficiency remained consistently high even after four desorption-readsorption cycles. • The sorption process was feasible, spontaneous, and endothermic in nature. [ABSTRACT FROM AUTHOR]

A weak electric field (WEF, 2 mA cm−2) was employed to promote Fe(III)/Fe(II) cycle on goethite-impregnated activated carbon (FeOOH@AC) filled in a continuous-flow column for enhanced Cr(VI) elimination from water. Surficial analysis and Cr species distribution showed that α-FeOOH of 0.2–1 μm was successfully synthesized and evenly loaded onto AC. Electron transfer from WEF to α-FeOOH was facilitated with AC as electron shuttles, thereby boosting Fe(III) reduction in the α-FeOOH. The generated Fe(II) reduced Cr(VI) and the resultant Cr(III) subsequently precipitated with OH− and Fe(III) to form Cr(OH) 3 and (Cr χ Fe 1-χ)(OH) 3. Therefore, the WEF-FeOOH@AC column exhibited a much lower Cr(VI) migration rate of 0.0018 cm PV−1 in comparison with 0.0037 cm PV−1 of the FeOOH@AC column, equal to 104 % higher Cr(VI) elimination capacity and 90 % longer column service life-span. Additionally, under different Cr(VI) loadings by varying either seepage velocities or influent Cr(VI) concentrations, the WEF-FeOOH@AC column maintained 1.0–1.5 folds higher Cr(VI) elimination and 0.9–1.4 folds longer longevity than those of the FeOOH@AC column owing to the interaction between FeOOH@AC and WEF. Our research demonstrated that WEF-FeOOH@AC was a potential method to promote Cr(VI) elimination from water and offer an effective strategy to facilitate Fe(III)/Fe(II) cycle in iron oxides. [Display omitted] • Weak electric field promoted Fe(III)/Fe(II) cycle on FeOOH@AC by transferring cathodic electrons with AC as shuttles. • WEF-FeOOH@AC could effectively eliminate Cr(VI) by adsorption, reduction, and sequestration. • The WEF-FeOOH@AC column also exhibited excellent resistance to shock Cr(VI) loadings. [ABSTRACT FROM AUTHOR]

In aquifers, the sequestration and transformation of organic carbon are closely associated with soil iron oxides and can facilitate the release of iron ions from iron oxide minerals. There is a strong interaction between dissolved organic matter (DOM) and iron oxide minerals in aquifers, but the extent to which iron is activated by DOM exposure to active iron minerals in natural aquifers, the microscopic distribution of minerals on the surface, and the mechanisms involved in DOM molecular transformation are currently unclear. This study investigated the nonbiological reduction transformation and coupled adsorption of iron oxide minerals in aquifers containing DOM from both macro- and micro perspectives. The results of macroscopic dynamics experiments indicate that DOM can mediate soluble iron release during the reduction of iron oxide minerals, that pH strongly affects DOM removal, and that DOM is more efficiently degraded at low rather than high pH values, suggesting that a low pH is conducive to DOM adsorption and oxidation. Spherical aberration-corrected scanning transmission electron microscopy (SACTS) indicates that the reacted mineral surfaces are covered with large amounts of carbon and that dynamic agglomeration of iron, carbon, and oxygen occurs. At the nanoscale, three forms of DOM are found in the mineral surface agglomerates (on the surfaces, inside the surface agglomerates, and in the polymer pores). The microscopic organic carbon and iron mineral reaction patterns can form through oxidation reactions and selective adsorption effects. Fourier transform ion cyclotron resonance mass spectra indicate that both synergistic and antagonistic reactions occur between DOM and the minerals, that the release of iron is accompanied by DOM decomposition and humification, that large oxygen- and carbon-containing molecules are broken down into smaller oxygen- and carbon-containing compounds and that more molecules are produced through oxidation under acidic rather than alkaline conditions. These molecules provide adsorption sites for sediment, meaning that more iron can be released. Microscopic evidence for the release of iron was acquired. These results improve the understanding of the geochemical processes affecting iron in groundwater, the nonbiological transformation mechanisms that occur at the interfaces between natural iron minerals and organic matter, groundwater pollution control, and the environmental behavior of pollutants. • DOM can mediate the release of soluble Fe from the reduction of soil iron oxide minerals. • Adsorption and oxidation of molecules occur on the mineral surface after DOM action. • Conversion of DOM molecules by minerals through decomposition and condensation, etc. • The release of Fe is accompanied by decomposition and humification of DOM. • Simultaneous synergism and antagonism in the reaction of DOM with minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] The adhesion of dissimilatory iron reducing bacteria (DIRB) to iron oxides is an important process to initiate direct extracellular electron transfer. Iron oxides in natural environments are often coated by organic matter or silica (SiO 2) which alters their surface physicochemical properties. To investigate the influence of these surface coatings, we characterized the dynamic adhesion processes of Shewanella oneidensis MR-1 to bare hematite, humic acid-coated hematite (hematite-HA), and SiO 2 -coated hematite (hematite-SiO 2) using Quartz Crystal Microbalance with Dissipation (QCM-D). The molecular-level process and mechanism were investigated using in situ Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectrometry. We found that MR-1 formed a rigid bacterial layer on bare hematite. Coating with HA or SiO 2 decreased the surface cell density during the initial adhesion stage, and compromised the stability of the subsequent bacterial attachment. The FTIR combined with two-dimensional correlation spectroscopy (2D-COS) analysis showed that C-moieties of polysaccharides dominated interactions in initial adhesion on HA and SiO 2 -coated hematite. In the longer term, the HA coating hindered the adsorption of amide, but promoted the binding of polysaccharide C-moieties to hematite. We concluded that, in general, both the HA and SiO 2 coatings reduced the attachment of MR-1 on hematite. These results advance our understanding of the roles of surface coatings on microbe-mineral interactions, which has significant implications for a series of biogeochemical processes in nature. [ABSTRACT FROM AUTHOR]

[Display omitted] Access to detailed information on cells loaded with nanoparticles with nanoscale precision is of a long-standing interest in many areas of nanomedicine. In this context, designing a single experiment able to provide statistical mean data from a large number of living unsectioned cells concerning information on the nanoparticle size and aggregation inside cell endosomes and accurate nanoparticle cell up-take is of paramount importance. Small-angle X-ray scattering (SAXS) is presented here as a tool to achieve such relevant data. Experiments were carried out in cultures of B16F0 murine melanoma and A549 human lung adenocarcinoma cell lines loaded with various iron oxide nanostructures displaying distinctive structural characteristics. Five systems of water-dispersible magnetic nanoparticles (MNP) of different size, polydispersity and morphology were analyzed, namely, nearly monodisperse MNP with 11 and 13 nm mean size coated with meso -2,3-dimercaptosuccinic acid, more polydisperse 6 nm colloids coated with citric acid and two nanoflowers (NF) systems of 24 and 27 nm in size resulting from the aggregation of 8 nm MNP. Up-take was determined for each system using B16F0 cells. Here we show that SAXS pattern provides high resolution information on nanoparticles disposition inside endosomes of the cytoplasm through the structure factor analysis, on nanoparticles size and dispersity after their incorporation by the cell and on up-take quantification from the extrapolation of the intensity in absolute scale to null scattering vector. We also report on the cell culture preparation to reach sensitivity for the observation of MNP inside cell endosomes using high brightness SAXS synchrotron source. Our results show that SAXS can become a valuable tool for analyzing MNP in cells and tissues. [ABSTRACT FROM AUTHOR]

[Display omitted] • Influence Cu on WGS catalysts under ambient (2 bar) and industrial (25 bar) conditions. • Mössbauer spectroscopy used for phase identification. • Cu doping favors ferrihydrite at the expense of hematite in the precursor. • Cu forms a metallic phase at the surface after activation, enhances WGS activity. • Copper does not affect the Fe2+/Fe3+ ratio in magnetite unlike chromium. Copper promotion of chromium-doped iron oxide prepared via co-precipitation for high-temperature water–gas shift (WGS) catalysis is investigated. Low-temperature Mössbauer spectra demonstrate that copper doping delays hematite (α-Fe 2 O 3) formation in the fresh catalyst, favoring the formation of small crystallites of ferrihydrite (Fe 5 HO 8 ∙4 H 2 O). Catalysts are treated under industrial WGS conditions at 360 °C (activity evaluation) and 450 °C (ageing) at 2 and 25 bar. Mössbauer spectra show that chromium is incorporated in octahedral sites of the active magnetite (Fe 3 O 4) phase, resulting in a partially oxidized structure. Copper doping did not affect the bulk magnetite structure of the activated catalyst, which points to the presence of a separate copper phase. Near-ambient pressure XPS shows that copper is in the metallic state. XPS of discharged catalysts evidenced that reaction at elevated pressure resulted in the surface reduction of Fe3+ to Fe2+. Copper promotion enhances CO conversion under high-temperature WGS conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] Iron oxide nanoparticles have been extensively studied for a wide variety of applications. However, there remains a challenge in developing hierarchical magnetic iron oxide nanoparticles as existing synthetic techniques require harsh, toxic chemical conditions and high temperatures or give poorly defined product with weak magnetic properties. In addition, drug loading is limited to post-loading methods such as chemical conjugation or surface adsorption that have poor loading efficiency and are prone to premature drug release. We report a facile biomimetic method for making iron oxide nanoparticle-loaded silica nanocapsules based on a bimodal catalytic peptide surfactant stabilized nanoemulsion template. Iron oxide nanoparticles can be preloaded into the oil phase of the nanoemulsion at tunable concentrations, and the excellent surface activity of the designed bimodal peptide in combination with sufficient electrostatic repulsion promotes the stability of the nanoemulsions. Biosilicification induced by the catalytic peptide module leads to the formation of silica shell nanocapsules containing a magnetic oil core. The bioinspired silica nanocapsules encapsulating iron oxide nanoparticles demonstrate the next-generation of magnetic nanostructures for drug delivery applications. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, perovskite intercalated montmorillonite (MMT) composite catalyst loaded by different mass fraction iron oxide, xFe 2 O 3 /LaCu 0.5 Co 0.5 O 3 -MMT 0.2 (x was the mass fraction of Fe 2 O 3 and x = 0.02, 0.04, 0.06), were prepared by impregnation method, and their catalytic activity were evaluated by microwave induced catalytic degradation of bisphenol A (BPA). Fe 2 O 3 had a certain absorption effect on microwave, which could enhance the absorption property of composite material, improve the catalytic activity of catalyst. XRD, SEM, XPS and vector network analysis were used to analysis the structure, morphology, surface element composition and microwave absorption performance of the composite catalyst. The results indicated that the sample had uniform structure, a larger specific surface, a higher ratio of O ads /O lat and excellent microwave absorption performance. The effects of microwave power, pH value and H 2 O 2 dosage on the catalytic degradation performance were studied, and 0.04Fe 2 O 3 /LCCOM 0.2 had the most obvious effect on the removal of BPA. The possible reaction mechanisms were discussed by characterization and experimental results of free radical capture. The surface active sites of the catalyst could be excited by microwave to generate oxidative free radicals, which could degrade BPA through electron hole transport. Response surface methodology (RSM) was used to optimize the operation parameters for the 0.04Fe 2 O 3 /LCCOM 0.2 -BPA microwave degradation system. [ABSTRACT FROM AUTHOR]

Luminescent magnetic nanocomposites are of interest because of their promising applications in the biomedical field. This article reports the preparation of silica-coated lanthanide terephthalate complexes, Ln-TA (Ln = Tb and Eu) containing luminescent magnetic nanocomposites. Cubic-shaped iron oxide nanoparticles were synthesized through the thermal decomposition of the iron-oleate complex. Then, polymerization of tetraethyl ortho silicate in a water-in-oil reverse microemulsion in the presence of previously prepared iron oxide nanocubes and a terbium (Tb3+)/europium (Eu3+)-terephthalate (TA) complex was performed to obtain luminescent magnetic Fe 3 O 4 @Ln-TA (Ln = Tb, Eu)/SiO 2 nanocomposites. The size (8.9 nm) and cubic shape of magnetic core were determined via transmission electron microscopy and the superparamagnetic behavior using a vibrating sample magnetometer. Energy dispersive X-ray analysis and inductively coupled plasma optical emission spectroscopy found that the luminescent Tb-TA and Eu-TA complexes were incorporated in the magnetic silica nanocomposites. The nanocomposites, Fe 3 O 4 @Ln-TA/SiO 2 , exhibited distinct luminescent green and red emission peaks and showed promise as a T 1 contrast agent for magnetic resonance imaging. [Display omitted] • Tb/Eu Terephthalate complex and cubic shaped Fe 3 O 4 nanoparticles were incorporated together in a uniform silica matrix by water-in-oil (w/o) reverse microemulsion. • The well-defined core-shell nanocomposite synthesis was influenced by the number of solid particles in microemulsion and TEOS amount. • The nanocomposites Fe 3 O 4 @Ln-TA/SiO 2 exhibited distinct green and red emission peaks. • The luminescence property of the nanocomposites was influenced by the nature of the suspending media. [ABSTRACT FROM AUTHOR]

• CO oxidation on FeO/Pt(1 1 1) occurs on FeO/FeO 2 interface along the islands edge as the "reaction zone". • Strong size effect on the light-off temperature of FeO 2−x islands below 5 nm in size. • Combined thermal desorption and STM experiments revealed weaker O bonding on the island edges. • An extended DFT analysis provided insight into the bonding of various oxygen species in such systems. Transition metal oxide layers on metal surfaces often show superior catalytic performance as compared to conventional, i.e. , metal-on-oxide, systems. In this work, we studied the CO oxidation reaction over FeO supported by Pt(1 1 1) and observed strong size effects on the reactivity. The monolayer islands below 5 nm in size showed a light-off temperature for CO 2 production 200 K lower than for the 30 nm islands. In an attempt to rationalize the size effect, we have performed oxygen desorption experiments and have combined them with an extended DFT analysis to provide insight into the bonding of various oxygen species in such systems. The theoretical results on isolated FeO 2 islands indicate a substantially lower stability of the boundary oxygen atoms as compared with the same islands embedded into an FeO layer in qualitative agreement with experiment showing that the smaller the island, the lower the desorption temperature. To the best of our knowledge, the results demonstrate the first example of a size effect in oxidation catalysis on two-dimensional systems. [ABSTRACT FROM AUTHOR]

• LEIS improves the accuracy of component additive surface complexation models. • Component additivity using bulk composition failed due to surface coatings. • Only LEIS truly captured iron oxide surface enrichment, XRF and XPS did not. • SCM modelling of As(III) required addition of surface precipitation reactions. Novel composite materials are increasingly developed for water treatment applications with the aim of achieving multifunctional behaviour, e.g. combining adsorption with light-driven remediation. The application of surface complexation models (SCM) is important to understand how adsorption changes as a function of pH, ionic strength and the presence of competitor ions. Component additive (CA) models describe composite sorbents using a combination of single-phase reference materials. However, predictive adsorption modelling using the CA-SCM approach remains unreliable, due to challenges in the quantitative determination of surface composition. In this study, we test the hypothesis that characterisation of the outermost surface using low energy ion scattering (LEIS) improves CA-SCM accuracy. We consider the TiO 2 /Fe 2 O 3 photocatalyst-sorbents that are increasingly investigated for arsenic remediation. Due to an iron oxide surface coating that was not captured by bulk analysis, LEIS significantly improves the accuracy of our component additive predictions for monolayer surface processes: adsorption of arsenic(V) and surface acidity. We also demonstrate non-component additivity in multilayer arsenic(III) adsorption, due to changes in surface morphology/porosity. Our results demonstrate how surface-sensitive analytical techniques will improve adsorption models for the next generation of composite sorbents. [ABSTRACT FROM AUTHOR]

This study explores the use of differential heating of magnetic nanoparticles with different sizes and compositions (MFe 2 O 4 (M = Fe, Co)) for heteroplexed temporal controlled release of conjugated fluorophores from the surface of nanoparticles. By exploiting these differences, we were able to control the amount of hysteretic heating occurring with the distinct sets of magnetic nanoparticles using the same applied alternating magnetic field radio frequency (AMF-RF). Using thermally labile retro-Diels-Alder linkers conjugated to the surface of nanoparticles, the fluorescent payload from the different nanoparticles disengaged when sufficient energy was locally generated during hysteretic heating. 1H, 13C NMR, ESI-MS, and SIMS characterized the thermally responsive fluorescent cycloadducts used in this study; the Diels Alder cycloadducts were modeled using density functional theory (DFT) computations. The localized point heating of the different nanoparticle compositions drove the retro-Diels-Alder reaction at different times resulting in higher release rates of fluorophores from the CoFe 2 O 4 compared to the Fe 3 O 4 nanoparticles. [ABSTRACT FROM AUTHOR]

• The Vo content of Fe 2 O 3 nanoplates is tuned by annealing at different temperatures. • Fe 2 O 3 with the oxygen vacancy content of 17% has the highest capacity. • The SSC shows a high energy density of 58.5 Wh kg−1 at a power density of 9.32 kW kg−1. As a promising anode material for supercapacitors, Fe 2 O 3 has been widely studied but still face the problem of low conductivity. Inducing oxygen vacancy (Vo) into Fe 2 O 3 is a widely used approach to tune the conductivity to enhance its capacitive performance, but there is little research on the influence of Vo content. Herein, we report the effect of Vo in Fe 2 O 3 nanoplates with various content. We tuned the Vo content by annealing at 200–500 °C. XPS and EPR were taken to characterize the Vo content, ranging from 11% to 26%. Electrochemical results show that FO-300 with 17% Vo has the highest capacity of 301 mAh g−1, and the capacity of the highest Vo content's (26% Vo) is only 107 mAh g−1. The symmetric supercapacitor based on FO-300 shows a considerably high energy density of 58.5 Wh kg−1 at a power density of 9.32 kW kg−1 and remains 84.6% after 12,000 cycles. [ABSTRACT FROM AUTHOR]

The subventricular zone (SVZ) is a neurogenic niche in the mammalian brain, giving rise to migratory neural progenitor cells (NPC). In rodents, it is well-established that neurogenesis decreases with aging. MRI-based cell tracking has been used to measure various aspects of neurogenesis and NPC migration in rodents, yet it has not yet been validated in the context of age-related decrease in neurogenesis. This validation is critical to using these MRI techniques to study changes in neurogenesis that arise in diseases prevalent in aging populations and their combination with advanced cellular therapeutic approaches aiming to combat neurodegeneration. As such, in this work we used MRI-based cell tracking to measure endogenous neurogenesis and cell migration from the SVZ along the rostral migratory stream to the olfactory bulb, for 12 days duration, in rats aged 9 weeks to 2 years old. To enable the specific detection of NPCs by MRI, we injected micron sized particles of iron oxide (MPIOs) into the lateral ventricle to endogenously label cells within the SVZ, which then appeared as hypo-intensive spots within MR images. In vivo MRI data showed that the rate of NPC migration was significantly different between all ages examined, with decreases in the distance traveled and migration rate as age progressed. The total number of MPIO-labeled cells within the olfactory bulb on day 12, was significantly decreased when compared across ages in ex vivo high-resolution scans. We also demonstrate for the first-time, provocative preliminary data suggesting age-dependent MPIO uptake within the dentate gyrus (DG) as well. Histology to identify doublecortin-positive NPCs, verified the decrease in cell labeling as a function of aging, for both regions. The dramatic reduction of NPC labeling within the SVZ observed with MRI, validates the sensitivity of MRI-based cell tracking to neurogenic potential and demonstrates the importance of understanding the impact of age on the relationship of NPC and disease. Image 1 •. MRI enables serial monitoring of endogenous neural progenitor cell (NPC) migration. •. In situ labeling of endogenous NPCs with magnetic particles yields MRI signature. •. Decreased NPC migration in aged rats measured by MRI matches histology, literature. •. First evidence of magnetic cell labeling and MRI of cells in dentate gyrus. [ABSTRACT FROM AUTHOR]

Tofacitinib (TOF) is gaining recognition as a potent therapeutic agent for a variety of autoimmune disorders, including rheumatoid arthritis and psoriasis. Ensuring precise drug concentration control during treatment necessitates a rapid and sensitive detection method. This study introduces a novel electrochemical sensor employing a composite of nanodiamond (ND), copper aluminate spinel oxide (CuAl 2 O 4), and iron (II, III) oxide (Fe 3 O 4) as modified materials for efficient TOF detection. Extensive analyses using physicochemical and electrochemical techniques were carried out to characterize the morphological, structural, and electrochemical properties of the ND@CuAl 2 O 4 @Fe 3 O 4 composite. Thereafter, various voltammetric methods were utilized to evaluate the electrochemical behavior of the ND@CuAl 2 O 4 @Fe 3 O 4 -modified glassy carbon electrode (GCE) concerning TOF determination. The fabricated electrode showcased superior performance in electrochemical TOF detection in a buffered solution (pH = 5), achieving a remarkably low detection limit of 7.8 nM and a linear response from 0.05 μM to 13.21 μM. Furthermore, applying the modified electrode as an electrochemical sensor exhibited exceptional selectivity, stability, and practicality in determining TOF in pharmaceutical and biological samples. Alongside the sensor development, this study conducted a thorough investigation using Density Functional Theory (DFT) for the geometry optimization of TOF and the TOF-ND complex. Consequently performed molecular docking studies using Janus Kinase 1 (JAK1) (PDB ID: 3EYG) and JAK3 (PDB ID: 3LXK) indicated higher interaction of the TOF-ND conjugate with the JAKs, reflected by binding energies of −12.9 kcal/mol and −11.7 kcal/mol for JAK1 and JAK3 respectively, compared to −7.0 kcal/mol and −6.9 kcal/mol for TOF alone. These findings illustrate the potential of the ND-based ND@CuAl2O4@Fe3O4 composite as a proficient sensing material for TOF detection and the merits of DFT in providing a detailed understanding of the interactions at play. This pioneering research holds promise for real-time TOF monitoring, which will advance personalized treatment strategies and improve therapeutic outcomes for patients with autoimmune disorders. • Developed novel sensor using ND@CuAl 2 O 4 @Fe 3 O 4 for Tofacitinib detection. • ND@CuAl 2 O 4 @Fe 3 O 4 electrode showcases superior electrochemical metrics. • Sensor proven effective in real-world pharmaceutical/biological samples. • Utilized DFT and molecular docking for TOF interaction mapping. • TOF-ND conjugate shows enhanced affinity towards JAK1 and JAK3. [ABSTRACT FROM AUTHOR]

Exposure to geogenic (earth-derived) particulate matter (PM) is linked to an increased prevalence of bronchiectasis and other respiratory infections in Australian Indigenous communities. Experimental studies have shown that the concentration of iron in geogenic PM is associated with the magnitude of respiratory health effects, however, the mechanism is unclear. We investigated the effect of geogenic PM and iron oxide on the invasiveness of non-typeable Haemophilus influenzae (NTHi). Peripheral blood mononuclear cell-derived macrophages or epithelial cell lines (A549 & BEAS-2B) were exposed to whole geogenic PM, their primary constituents (haematite, magnetite or silica) or diesel exhaust particles (DEP). The uptake of bacteria was quantified by flow cytometry and whole genome sequencing (WGS) was performed on NTHi strains. Geogenic PM increased the invasiveness of NTHi in bronchial epithelial cells. Of the primary constituents, haematite also increased NTHi invasion with magnetite and silica having significantly less impact. Furthermore, we observed varying levels of invasiveness amongst NTHi isolates. WGS analysis suggested isolates with more genes associated with heme acquisition were more virulent in BEAS-2B cells. The present study suggests that geogenic particles can increase the susceptibility of bronchial epithelial cells to select bacterial pathogens in vitro , a response primarily driven by haematite content in the dust. This demonstrates a potential mechanism linking exposure to iron-laden geogenic PM and high rates of chronic respiratory infections in remote communities in arid environments. • Geogenic particles are linked to severe respiratory infections in Indigenous Australian communities, but the mechanism is unknown. • Particles containing haematite increased susceptibility of the airway epithelium to invasion by non-typeable Haemophilus influenzae. • Whole genome sequencing identified genes related to heme acquisition that were associated with this response. • This has implications for communities exposed to high levels of iron-laden particles. [ABSTRACT FROM AUTHOR]

Chitosan-magnetic-graphene oxide (CMGO) nanocomposite was prepared for arsenic adsorption. The nanocomposite was characterized through BET, FTIR, FESEM, EDX, and VSM analyses. These characterizations confirmed the formation of CMGO nanocomposites with high specific surface area (152.38 m2/g) and excellent saturation magnetization (49.30 emu/g). Batch adsorption experiments were conducted to evaluate the performance of the nanocomposite in the adsorption of arsenic from aqueous solution. The effects of operational parameters, adsorption kinetic, equilibrium isotherm and thermodynamics were evaluated. The removal efficiency of arsenic increased with increasing adsorbent dosage and contact time. However, the effect of pH followed a different pattern, with the removal efficiency increasing from acidic to neutral pH, and then decreasing at alkaline conditions. The highest adsorption capacity (45 mg/g) and removal efficiency (61%) were obtained at pH 7.3. The adsorption kinetic followed a pseudo-second-order kinetic model. The analysis of adsorption isotherm shows that the adsorption data fitted well to Langmuir isotherm model, indicating a homogeneous process. Thermodynamic analysis shows that the adsorption of As(III) is exothermic and spontaneous. The superparamagnetic properties of the nanocomposite enabled the separation and recovery of the nanoparticles using an external magnetic field. Thus, the developed nanocomposite has a potential for arsenic remediation. • Chitosan magnetic graphene oxide (CMGO) was prepared for As(III) adsorption. • CMGO exhibits high specific surface area (152 m2/g) and abundant functional groups. • Highest adsorption capacity and As(III) removal at circumneutral pH. • Adsorption process controlled by surface complex formation. • Easy separation and recovery of CMGO nanoparticles by external magnetic field. [ABSTRACT FROM AUTHOR]

Surfactants are easily accumulated in groundwater, sediment, and aquifers, due to their excessive use in household, industrial, and agricultural processes. These residual surfactants are expected to influence the transformation and fate of organic contaminants by Fe(II) sorbed on iron oxides in anaerobic environments. Here, we investigated the effects of various surfactants including nonionic TX-100, anionic SDBS and bio-surfactant saponin on the removal of nitrobenzene (NB) by Fe(II) sorbed on goethite (goethite/Fe(II)) through batch experiments. We also elucidated the mechanism behind the effects by XPS, XRD, and determination of the amounts of sorbed Fe(II) on goethite. The results showed that the presence of TX-100 improved NB removal from 77.2% in the absence of surfactant, to 93.8% within 6 h, and improved the removal rate by about 1.3 times. In contrast, the presence of SDBS decreased the removal efficiency to 45.5%, and the presence of saponin nearly inhibited the removal of NB completely. The removed NB was finally nearly reduced to aniline in the absence or presence of surfactants, except in the case of saponin. The amounts of sorbed Fe(II) listed in the sequence as goethite/Fe(II)+TX-100 > goethite/Fe(II) > goethite/Fe(II)+SDBS > goethite/Fe(II)+saponin, and this order negatively correlated with that in the redox potential of these systems. These results confirmed that the presence of surfactants influenced the sorption of Fe(II) on goethite and changed the reactivity of goethite/Fe(II) for NB removal. This finding will promote a clear understanding of the impact of coexisting surfactants on the transformation and fate of organic contaminants in real anaerobic environments. [ABSTRACT FROM AUTHOR]

The electrochemical nitrogen reduction reaction (NRR) under mild conditions is significantly challenging, due to the extremely high stability of dinitrogen (N 2) molecules. The NRR pathway also confronts the competitive water reduction reaction that takes places universally in an aqueous solution. Herein, a Fe 2 O 3 /Cu catalyst is demonstrated as an efficient NRR electrocatalyst. The electronic interactions elevate the d -state electron center, enabling strong back-bonding for N 2 molecules. The altering of d -electron distribution promotes the adsorption of N 2 , leading to a high catalytic activity. As a result, the Fe 2 O 3 /Cu catalyst exhibits an outstanding ammonia production rate of 15.66 μg·h−1·mg cat. −1 at −0.1 V versus reversible hydrogen electrode (RHE), a Faradaic efficiency of 24.4%, and a good electrochemical stability. [ABSTRACT FROM AUTHOR]

Anaerobic batch tests with a 22 full-factorial design of ammonia (1.5, 6.5 g N/L) and magnetite concentrations (0, 20 mmol/L) were conducted separately for methanogenic degradation of acetate, propionate, and butyrate (volatile fatty acids (VFAs)) to 1) quantify the effect of magnetite as an enhancer in methanogenic degradation of each of the VFAs in conditions without ammonia stress (1.5 g N/L) and with ammonia stress (6.5 g N/L), and 2) identify methanogenic consortia that are related to such enhancement. Among the three VFAs, methanogenic degradation of propionate was the least feasible (57% lower specific methanogenic activity R CH4 and three times longer lag time λ than acetate degradation). At low ammonia concentration, only propionate showed improvement in R CH4 (46%) with supplementation of magnetite. In the ammonia-stressed condition without magnetite, R CH4 decreased by 38–58% and λ increased 2.2–8.8 times for all VFAs; magnetite supplementation significantly alleviated these effects. These results demonstrate that magnetite supplementation effectively increases methanogenic degradation of the VFAs even under ammonia-stressed conditions. 16S metagenomic sequencing revealed that distinctive methanogenic consortia were active in the different combinations of substrate, ammonia and magnetite. Alkaliphilus , Hyphomonadaceae SWB02 and Clostridia DTU014 , Clostridia D8A-2 , Christensenellaceae R-7 group and Rikenellaceae DMER64 were identified as potential syntrophic bacteria that can establish magnetite-mediated direct electron transfer with methanogens (Methanosaeta concilii , Methanosaeta harundinacea , Methanolinea tarda , Methanoculleus bourgensis and Methanosarcina spp.) during methanogenic degradation of VFAs. The results may be useful as a reference to develop effective strategies using magnetite supplementation to remediate anaerobic digestion processes that have been afflicted by VFA accumulation and ammonia inhibition. • Magnetite effect on AD of VFAs under NH 3 -stressed condition was tested. • Methanogenic degradation of propionate was improved by magnetite addition. • Magnetite alleviated NH 3 inhibition of methanogenic degradation of VFAs. • Distinctive syntrophic consortia were responsible for such enhancement effect. [ABSTRACT FROM AUTHOR]

Abstract We present the successful synthesis and characterization of pure and Al: Fe 2 O 3 thin films prepared by spray pyrolysis. The XRD analysis showed a rhomboedric structure with (104) as a preferential orientation for all the layers. AFM and SEM observations exhibited a dense surface with grains uniformly distributed. Optical measurements demonstrated that Al: Fe 2 O 3 (y = 6 and 8 at. %) were highly transparent. In addition, the band gaps values found in the range from 1.98 to 2.17 eV. Hall Effect measurements indicated an n-type conductivity with the lowest resistivity of 2.68 x 102 Ω.cm which reached for the 8 at. % Al: Fe 2 O 3 thin films. Moreover, Al: Fe 2 O 3 thin film based sensor demonstrated a good response to a small amount of ethanol vapor with the adequate response and recovery period at a low operating temperature equal to 250 °C. Highlights • The n -type Fe 2 O 3 :Al thin films with low resistivity were obtained by spray method. • All the thin films of Fe 2 O 3 :Al have (104) as a preferential orientation. • The electrical properties of Fe 2 O 3 :Al are extremely sensitive to the aluminum doping. • Film doped with 8 at. % Al concentration exhibits a fast response to low gas concentration. [ABSTRACT FROM AUTHOR]

Highlights • Pigment production into the mining process in Andean region. • Different phases of the production sequence in association to habitational structures. • Pigment production in the negotiation between different social entities. • Pigment consumption in the Atacama Desert during Late pre-Hispanic periods. • Inca expansion defines new sociopolitical rules related to local negotiation. Abstract The mineral richness of the Atacama Desert permitted the development of a diverse array of mining activities, including the production of metals, lapidary, and pigments, which developed into significant sociocultural practices for desert dwellers throughout the occupation of the region. El Cóndor mine is an important hematite source located in the middle section of the Loa River, exploited from the Formative Period (ca. AD 300) until Inca times (ca. AD 1500). In contrast to other mining sites of Atacama region, the El Condor mine complex contains specialized infrastructure where different kinds of activities were carried out: extraction pits, processing areas with multiple anvils and grinding tools, and semicircular structures used for domestic activities. Pigment production was initially developed as a small-scale craft that intensified during later periods (ca. AD 1200). It was most extensive following the Inca expansion (ca. AD 1400), as evidenced by wider networks of distribution and consumption, as well as infrastructural changes. El Cóndor mine constitutes a notable example of a large-scale hematite operation that articulated important networks of exchange, and as such provides a case study for evaluating the organization of mining activities during late periods of the pre-Hispanic sequence in the Atacama Desert. We then emphasize that the circulation of pigments constitutes an important social practice and a salient economic activity, fulfilling a political role through the production and reproduction of social relations between different cultural entities that could be compared to similar cases from other regions in the world. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract A three-component nano-electrocatalyst, magnetite coated molybdenum disulfide hybridized with reduced graphene oxide (Fe 3 O 4 @MoS 2 /RGO), is synthesized by a two-step hydrothermal method. This catalyst is applied as an effective substitution for the platinum catalyst in methanol oxidation and hydrogen evolution reactions. Cyclic voltammetry, chronoamperometry, and linear sweep voltammetry are used to evaluate the performance of the electrocatalyst in acidic and basic media. The results of methanol oxidation reaction on the hybridized nano-electrocatalyst showed good electrocatalytic properties with considerable diffusion currents. This fact is confirmed by the Tafel plots and the calculated kinetic parameters of electron transfer. Fe 3 O 4 @MoS 2 /RGO showed an anodic transfer coefficient and exchange current of 0.464 and 4.80 × 10−8, respectively that are higher than Fe 3 O 4 /RGO. The presence of the porous MoS 2 in catalyst has a key effect on supplying electroactive sites for electron transfer. Also, the high actual surface area obtained for the hybridized nano-electrocatalyst (A = 0.0295 cm2). The maximum power density of 35.03 mW cm−2 obtained for a single cell containing the prepared hybridized catalyst as the anode which shows a competitive feature of the synthetic catalyst compared to other reports. Furthermore, the synthetic catalyst shows the low-value overpotential of 108 mV and Tafel slope of 48 mV dec−1 during the hydrogen evolution process in acidic media. This is attributed to the synergistic effect between Fe 3 O 4 and MoS 2 and also increase the electron transfer rate due to adding conductive RGO to the catalyst. The results show that the synthetic nanocatalyst can have promising applications for hydrogen evolution and methanol oxidation reactions. [ABSTRACT FROM AUTHOR]

Stable and efficient oxygen evolution reaction (OER) catalysts for the oxidation of water to dioxygen in highly acidic media are currently limited to expensive noble metal (Ir and Ru) oxides since presently known OER catalysts made of inexpensive earth-abundant materials generally suffer anodic corrosion at low pH. In this study, we report that a mixed-polymorph film comprising maghemite and hematite, prepared using spray pyrolysis deposition followed by low-temperature annealing, showed a sustained OER rate (>24 h) corresponding to a current density of 10 mA cm −2 at an initial overpotential of 650 mV, with a Tafel slope of only 56 mV dec −1 and near-100% Faradaic efficiency in 0.5 M H 2 SO 4 (pH 0.3). This performance is remarkable, since iron (III) oxide films comprising only maghemite were found to exhibit a comparable intrinsic activity, but considerably lower stability for OER, while films of pure hematite were OER-inactive. These results are explained by the differences in the polymorph crystal structures, which cause different electrical conductivity and surface interactions with water molecules and protons. Our findings not only reveal the potential of iron (III) oxide as acid-stable OER catalyst, but also highlight the important yet hitherto largely unexplored effect of crystal polymorphism on electrocatalytic OER performance. [ABSTRACT FROM AUTHOR]

Much attention has been paid to the relationship between microbial iron reduction and the behavior of cadmium (Cd) recently, but most previous research has employed unrealistically high Cd concentrations (e.g., 2–55 mg L −1 ) and has failed to consider the effects of iron oxides and microbial cells together. We investigated the reduction of lepidocrocite by Shewanella oneidensis MR-1 in the presence of a low concentration of Cd using batch reactor systems. The results showed that with 422 μg L −1 added dissolved Cd 2+ , an initial 137 μg L −1 decrease in aqueous Cd occurred due to adsorption onto lepidocrocite and that the further removal of remaining aqueous Cd occurred only in the system containing bacteria. This further decrease in aqueous Cd was unlikely to be caused by mineral transformation because the microbial reduction of lepidocrocite resulted in particle-size-increased (thus, specific-surface-area-decreased) lepidocrocite, and unlikely to be caused by the pH increase to 7.4 induced by iron reduction either because a pH-adsorption edge suggested that at pH 7.4, less than 60% of aqueous Cd can be adsorbed by lepidocrocite in the reactors. An adsorption isotherm showed a significant Cd adsorption capacity by S. oneidensis MR-1 cells, and we therefore attributed the further Cd removal to adsorption by S. oneidensis MR-1 cells. The results suggest that a realistically low concentration of Cd can be immobilized during microbial iron reduction by adsorption on iron oxides and microbial cells. [ABSTRACT FROM AUTHOR]

Arsenic contamination is one of serious environmental problems in the world. In this study, an innovative yttrium-doped iron oxide magnetic adsorbent was synthesized through a simple precipitation method for better arsenic decontamination and ease in separation after the application. The adsorbent with a rough surface and porous structure was aggregated of nano-sized irregular particles after heat-drying procedure. The point of zero charge value of the adsorbent was about 7.0, giving good performance on the arsenate removal at weakly acidic and neutral conditions. The thermal gravimetric analysis, X-ray powder diffraction and X-ray photoelectron spectroscopy studies demonstrated that hydroxyl groups from goethite and amorphous species of the adsorbent were mainly responsible for the arsenic adsorption. The adsorption equilibrium of arsenate and arsenite was respectively established in 24 and 4 h. The maximum adsorption capacities of As(V) and As(III) at pH 7.0 were 170.48 and 84.22 mg-As/g, respectively. The better fit by the Freundlich isotherm indicated the mechanism of multi-layer adsorption for the removal. Our study demonstrated that the material would be suitable for treating arsenic-containing water with higher efficiency and ease in use. [ABSTRACT FROM AUTHOR]

Despite attractive properties for both therapeutic and diagnostic applications, the clinical use of iron oxide nanoparticles (IONPs) is limited to iron replacement in severely anemic patient populations. While several studies have reported about the immunotoxicity of IONPs, the mechanisms of this toxicity are mostly unknown. We conducted a mechanistic investigation using an injectable form of IONP, Feraheme®. In the cultures of primary human T cells, Feraheme induced miotochondrial oxidative stress and resulted in changes in mitochondrial dynamics, architecture, and membrane potential. These molecular events were responsible for the decrease in cytokine production and proliferation of mitogen-activated T cells. The induction of mitoROS by T cells in response to Feraheme was insufficient to induce total redox imbalance at the cellular level. Consequently, we resolved this toxicity by the addition of the mitochondria-specific antioxidant MitoTEMPO. We further used these findings to develop an experimental framework consisting of critical assays that can be used to estimate IONP immunotoxicity. We explored this framework using several immortalized T-cell lines and found that none of them recapitulate the toxicity observed in the primary cells. Next, we compared the immunotoxicity of Feraheme to that of other FDA-approved iron-containing complex drug formulations and found that the mitochondrial damage and the resulting suppression of T-cell function are specific to Feraheme. The framework, therefore, can be used for comparing the immunotoxicity of Feraheme with that of its generic versions, while other iron-based complex drugs require case-specific mechanistic investigation. [ABSTRACT FROM AUTHOR]

Hypothesis Ligand exchange is a widely-used method of controlling the surface chemistry of nanomaterials. Exchange is dependent on many factors including the age of the core particle being modified. Aging of the particles can impact surface structure and composition, which in turn can affect ligand binding. Experiments To quantify the effects of aging on ligand exchange, we employed a technique to track the exchange of radiolabeled 14 C-oleic acid with unlabeled, oleic acid bound to iron oxide nanoparticles. Liquid scintillation counting (LSC) was used to determine the amount of 14 C-oleic acid adsorbing to the particles throughout the duration of the exchange for particles aged for 2 days, 7 days, and 30 days. Findings Results revealed an increase in the total amount of ligands exchanged with aging up to 30 days. Kinetic analysis of these results revealed a significant decrease in the overall rate of ligand exchange between 2 and 30 days. The change in extent of adsorption with age could suggest increased availability of free binding sites. A follow-up study comparing exchange with oxidized and unoxidized particles suggested this increase in ligand adsorption may be due to changes in the Fe 2+ /Fe 3+ ratio on the surface as the particles aged. [ABSTRACT FROM AUTHOR]

Methylene Blue (MB) is a cationic dye causing various health problems such as asthma, heartbeat, eye and skin irritation, nausea, and distress during prolonged exposure. In this regard, the green magnetite nanoparticle was synthesized using the extract of Prosopis farcta. The synthesized Fe 3 O 4 nanoparticle was characterized by X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier transforms Infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), and Brunauer-Emmett-Teller (BET). The corresponding parameters, including the primary concentration of MB (5–65 mg/L), the dose of synthesized nanoparticle (0.025–0.925 g/L), solution pH (3–11), and contact time (20–60 min), were considered. Also, central composite design (CCD), as one of the response surface methodologies (RSM), was used for the related modelling and optimization. The particle size of the adsorbent was between 5 and 70 nm, and the nanoparticle has 206.75 m2/g of a specific surface, 6.1 nm of average pore size, and 0.3188 cm3/g of the total pore volume. The optimal conditions for MB removal by the nanoparticle were found to follow an initial MB concentration of 20 mg/L, 0.7 g/L of the nanoparticle dose, pH = 9, and a contact time of 50 min. The pseudo-second-order (PSO) and Freundlich models were the best kinetic and isothermal models for MB removal by the synthesized nanoparticle. Molecular modelling was used to optimize the MB molecular configuration and compute HOMO-LUMO energies, quantum-chemical descriptors, and molecular electrostatic potential to evaluate the nature reactivity of the MB molecule. [Display omitted] [ABSTRACT FROM AUTHOR]

The sustainable management of toner waste (T–raw) was performed via carbonization at 500 °C (T-500) and 600 °C (T–600) to produce iron oxide-nanographene nanohybrid (FeO-NG) for activating persulfate (PS) to efficiently degrade dyes (methylene blue, MB), antibiotics (sulfamethazine, SMZ), and pesticides (diazinon, DZN). Morphology, crystallinity, chemical structure, chemical composition, surface area, and pore size distribution of the synthesized materials were investigated using various analyses. High degradation ratios of MB were attained over a wide pH range (2–7), and the optimum operating conditions were determined. The FeO-NG/PS system was tested in different water matrices. MB degradation efficiency dropped from 80.13% to 78.56% after five succeeding experiments, proving the high stability of T–500. Trapping experiments proved the major role of sulfate radicals and the minor contribution of singlet oxygen. The toxicity evaluation of the treated and untreated MB solutions was conducted via measuring the cell viability, showing an increase in cell viability ratio after the degradation of MB. The degradation efficiencies of DZN and SMZ were 97.54% and 83.7%, respectively and the mineralization ratios were 74.08% and 60.37% at initial concentrations of sulfamethazine and diazinon of 50 and 100 mg/L, respectively. The high degradation efficiency of emerging micropollutants as well as the inexpensiveness, and facile synthesis of the catalyst boost the prospect of applying the proposed system on an industrial scale. [Display omitted] • 500 °C carbonization of toner waste yielded a porous and high surface FeO-NG. • FeO-NG can effectively activate persulfate to generate reactive oxygen species. • High degradation and mineralization of target pollutants were achieved. • Sulfate radicals were the dominant reactive species. • The toxicity of methylene blue decreased after the treatment by FeO-NG/PS system. [ABSTRACT FROM AUTHOR]

'Wealth from Waste' is an emerging concept, since it leads an effective waste treatment and waste recyclability. On the other hand, cost effective production iron oxide (IO) nanomaterials is still needed to develop, owing to their wide applications. Herein, we proposed a simple direct calcination method to prepare porous IO (Fe 3 O 4 and Fe 2 O 3) nanomaterials from waste toner powder. Characterization techniques reveal that a structural change happened from Fe 3 O 4 to γ-Fe 2 O 3 and γ-Fe 2 O 3 to α-Fe 2 O 3 at the calcination temperature of 500 °C and 700 °C respectively. Consequently, optical (band gap) and magnetic parameters of IO samples were significantly varied. The pigment characteristics of the IO samples were evaluated using Commission Internationale de l'Eclairage (CIE) analysis. IO900 sample has shown good brown-red coloration (L* = 43.11, a* = 13.26 and b* = 5.69) and it also exhibited good stability in acidic and basic conditions. Practical applicability of IO pigments were also tested by mixing with plaster of paris (PP) powder. Further, porous IO samples were also used as catalysts in the reductive degradation of methyl orange (MO) dye in presence of excess sodium borohydride (NaBH 4). IO, prepared at 900 °C exhibited ∼99.9% reduction efficiency within 40 min. Recycling experiments indicated that IO900 possess good stability up to seven cycles. The present porous IO samples will become potential in pigment and environmental remediation. [ABSTRACT FROM AUTHOR]

The conventional synthesis methods of magnetite nanoparticles by hydrothermal required high temperature and aging process, which results in an unstable magnetite phase. In this work, the focus is on producing magnetite nanoparticles by simple and sustainable titration methods with the variable in parameters on the precipitate growth rate and structure of iron oxide nanoparticles utilizing a single sulphate precursor. Iron salt precursor hydrolysis was faster at temperatures of 30 ​°C and 45 ​°C; hence the number of hydroxyl ions (OH−) needed to reach the equivalence point for the precipitate to form is lower, creating the highest percentage of magnetite nanoparticles. However, at 45 ​°C, larger magnetite nanoparticles were obtained hence higher magnetization through lower coercivity. Precipitating agent rate of addition increase leads to reaction sequence delay, favoring goethite nanoparticle formation and lower magnetization. The novel understanding of precipitation parameter synergistic effect has resulted in promising ferromagnetic and stabilization properties of magnetite nanoparticle synthesis. [Display omitted] • Precipitating parameters effect on the particle size and magnetism of Fe 3 O 4. • High rate of precipitating agents reduces the particle size and magnetism of Fe 3 O 4. • Synthesis at 45 ​°C and 5 ​ml/min gives the highest saturation magnetization hence with the smallest particle size. [ABSTRACT FROM AUTHOR]

A metakaolinite-hematite (KH) red pigment was prepared using an ocherous iron oxide sludge recovered from a water treatment plant of an abandoned coal mine. The KH pigment was prepared by heating the kaolinite and the iron oxide sludge at kaolinite's dehydroxylation temperature. Both the raw sludge and the KH specimen were characterised for their colour properties and toxic characteristics. The KH specimen could serve as a pigment for integrally coloured concrete and offers a potential use for the large volumes of the iron oxide sludge collected from mine water treatment plants. [ABSTRACT FROM AUTHOR]

Au@FeOx dumbbell nanocrystals (NCs) with different sizes of the Au domain (i.e. 4 nm, 6 nm and 10 nm) were successfully synthesized by means of a colloidal synthesis procedure. They were then deposited on γ-alumina and tested in CO oxidation. The use of alumina minimized the contribution of the Au-support interaction in the CO oxidation, thus enabling us to clearly identify a synergy between the Au and the iron oxide that eventually resulted in an enhanced activity in CO oxidation, good sintering resistance and good stability of the catalytic performances. Among the three gold sizes tested, the dumbbells with 4 nm Au domains were found to be the most active ones. Nevertheless, we found that the activity of the 4 nm dumbbells was significantly hampered by the limited exposure of the Au or of the Au/iron oxide interface to the reacting environment. [ABSTRACT FROM AUTHOR]

Hypothesis Phosphate influences the sorption of metals to iron (hydr)oxides. An enhanced formation of inner-sphere complexes on the (hydr)oxide surface can be attributed to electrostatic interactions and/or to changes in metal coordination on the iron (hydr)oxide surface. Phosphate was expected to increase cadmium(II) sorption on ferrihydrite. It should be possible to identify changes in cadmium(II) coordination upon phosphate addition by Extended X-ray absorption fine structure (EXAFS) spectroscopy and implement the identified complexes in a surface complexation model (SCM). Experiments The effect of phosphate addition on cadmium(II) sorption to ferrihydrite was studied by a series of batch experiments covering the pH range from 4 to 8. EXAFS spectroscopy was performed on ferrihydrite from the batch experiments at the cadmium K edge. The identified surface complexes were incorporated in the Charge distribution multisite complexation (CD-MUSIC) model, and new surface complexation constants were optimized. Findings Without phosphate addition cadmium(II) formed inner-sphere bidentate complexes on the ferrihydrite surface. With phosphate there was an increased cadmium(II) sorption that could not be explained by electrostatic interactions alone. The enhancement was best explained by the formation of a ternary complex including cadmium(II), phosphate and ferrihydrite surface groups. [ABSTRACT FROM AUTHOR]

Core-shell nanostructures of Zinc and Cobalt ferrites synthesized by solution evaporation route are observed to perform novel magnetic response. The structural and morphological analyses of ZnFe 2 O 4− core / Fe 3 O 4− shell and CoFe 2 O 4− core / Fe 3 O 4− shell nanoparticles (NPs) are confirmed with X-ray diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM). Physical properties measurement system (PPMS) investigations at room temperature reveal that the synthesized core-shell NPs (∼8 nm in diameter) are in super-paramagnetic state. The coercivity of ZnFe 2 O 4 / Fe 3 O 4 is much lower than that of CoFe 2 O 4 / Fe 3 O 4 NPs (e.g., at 5 K : H c = 0.6 kOe for ZnFe 2 O 4 / Fe 3 O 4 and H c = 18kOe for CoFe 2 O 4 / Fe 3 O 4 . Fe 3 O 4 is preferable to reduce magnetic hardness for Zinc ferrite and enhance for Cobalt Ferrite. [ABSTRACT FROM AUTHOR]

Magnetically responsive oil-in-water emulsions are effectively stabilized by a halloysite nanotube supported superparamagnetic iron oxide nanoparticle system. The attachment of the magnetically functionalized halloysite nanotubes at the oil–water interface imparts magnetic responsiveness to the emulsion and provides a steric barrier to droplet coalescence leading to emulsions that are stabilized for extended periods. Interfacial structure characterization by cryogenic scanning electron microscopy reveals that the nanotubes attach at the oil–water interface in a side on-orientation. The tubular structure of the nanotubes is exploited for the encapsulation and release of surfactant species that are typical of oil spill dispersants such as dioctyl sulfosuccinate sodium salt and polyoxyethylene (20) sorbitan monooleate. The magnetically responsive halloysite nanotubes anchor to the oil–water interface stabilizing the interface and releasing the surfactants resulting in reduction in the oil–water interfacial tension. The synergistic adsorption of the nanotubes and the released surfactants at the oil–water interface results in oil emulsification into very small droplets (less than 20 μm). The synergy of the unique nanotubular morphology and interfacial activity of halloysite with the magnetic properties of iron oxide nanoparticles has potential applications in oil spill dispersion, magnetic mobilization and detection using magnetic fields. [ABSTRACT FROM AUTHOR]

α-Fe 2 O 3 nanosheet-assembled hierarchical hollow mesoporous microspheres (HHMSs) were prepared by thermal transformation of nanosheet-assembled hierarchical hollow mesoporous microspheres of a precursor. The precursor was rapidly synthesized using FeCl 3 ·6H 2 O as the iron source, ethanolamine (EA) as the alkali source, and ethylene glycol (EG) as the solvent by the microwave-assisted solvothermal method. The samples were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption isotherm. The effects of the microwave solvothermal temperature and EA amount on the morphology of the precursor were investigated. The as-prepared α-Fe 2 O 3 HHMSs exhibit a good photocatalytic activity for the degradation of salicylic acid, and are promising for the application in wastewater treatment. [ABSTRACT FROM AUTHOR]

The biochemical mechanisms by which microbes interact with extracellular soluble metal ions and insoluble redox-active minerals have been the focus of intense research over the last three decades. The process presents two challenges to the microorganism. Firstly, electrons have to be transported at the cell surface, which in Gram-negative bacteria presents an additional problem of electron transfer across the ~ 6 nm of the outer membrane. Secondly, the electrons must be transferred to or from the terminal electron acceptors or donors. This review covers the known mechanisms that bacteria use to transport electrons across the cell envelope to external electron donors/acceptors. In Gram-negative bacteria, electron transfer across the outer membrane involves the use of an outer membrane β-barrel and cytochrome. These can be in the form of a porin-cytochrome protein, such as Cyc2 of Acidithiobacillus ferrooxidans, or a multiprotein porin-cytochrome complex like MtrCAB of Shewanella oneidensis MR-1. For mineral-respiring organisms, there is the additional challenge of transferring the electrons from the cell to mineral surface. For the strict anaerobe Geobacter sulfurreducens this requires electron transfer through conductive pili to associated cytochrome OmcS that directly reduces Fe(III)oxides, while the facultative anaerobe S. oneidensis MR-1 accomplishes mineral reduction through direct membrane contact, contact through filamentous extensions and soluble flavin shuttles, all of which require the outer membrane cytochromes MtrC and OmcA in addition to secreted flavin. [ABSTRACT FROM AUTHOR]

The introduction of biocompatible coatings onto nanoparticle surfaces can be synthetically challenging. In this work, calcium phosphate (brushite, CaHPO 4 ⋅2H 2 O), iron oxide (hematite, α-Fe 2 O 3 ), zinc oxide (ZnO), and CaHPO 4 @ZnO and α-Fe 2 O 3 @ZnO nanoparticles were synthesized and treated with the biocompatible, biodegradable, polysaccharide inulin {(2R,3S,4S,5R)-2-[[(2R,3S,4S,5R)-3,4-dihydroxy-2,5-bis(hydroxymethyl)oxolan-2-yl]oxymethyl]-5-(hydroxymethyl)oxolane-2,3,4-triol} under mild conditions. The products were fully characterized by Fourier transforms infrared (FTIR) spectroscopy, energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), differential thermogravimetric/differential thermal analysis (TGA/DTA), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). Surface interactions among hematite and brushite with inulin are weak, but coating the nanoparticle surface with ZnO increased the affinity toward the polysaccharide. Inulin adsorption on the nanoparticle surface was confirmed by thermal and spectroscopic analyses. The nanoparticles had diameters ranging from 50 to 80 nm, with nearly spherical morphology. The nanoparticles sizes, stability and solubility in water could make them useful as components for enriched foods. [ABSTRACT FROM AUTHOR]

The effects of soil fulvic (JGFA) and humic acid (JGHA) on Pb binding to goethite were investigated with batch experiments and modeling. The CD-MUSIC and NICA-Donnan model could describe the Pb binding to, respectively, the binary Pb–goethite and Pb–HS systems. The adsorption of humic substances (HS) on goethite strongly depended on pH and was promoted by Pb binding. The mass amount of adsorbed JGFA (mg/g) was smaller than that of JGHA, but when expressed in number of particles/nm 2 the JGFA adsorption was higher. At low pH and low initial Pb concentration the linear additivity rule always underestimated Pb adsorption to goethite–HS complex, which was caused by the strong effect of adsorbed HS on the electrostatic potentials in the Stern layer region. At other conditions except the 450 mg/L JGHA in the 0.5 mmol/L Pb system the additivity rule predicted the experimental results reasonably well, and at high pH nearly all Pb is bound to goethite. At the same mass adsorbed, the effect of JGFA on Pb adsorption to goethite is stronger than that of JGHA, due to the fact that the JGFA particles were primarily adsorbed in the Stern layer, whereas JGHA particles were present in both Stern layer and diffuse layer. Therefore, the electrostatic potential profile of the goethite-JGFA complex is considerably different from that of goethite-JGHA complex and affects Pb binding strongly. [ABSTRACT FROM AUTHOR]