Ferric Cations Research Articles

Tannin-encapsulated electrospun nanofibrous membrane of cellulose nanowhiskers-reinforced polysulfone for colorimetric detection of iron(III)

A nanocomposite of tannic acid and cellulose nanowhiskers (CNW)-reinforced polysulfone (PSF) was used to develop a metallochromic nanofibrous membrane sensor for iron(III) in aqueous media. Tannic acid was used as an active detecting probe, whereas the CNW@PSF composite was employed as a hosting material. Cellulose nanowhiskers (7–12 nm) were obtained from microcrystalline cellulose (MCC). According to the coloration parameters, a bathochromic shift from colorless (415 nm) to purple (561 nm) occurs when ferric cations bind to the phenolic hydroxyls of the tannic acid probe. The concentration of ferric was found to be directly correlated to the extent of the color change, demonstrating a detection limit of 0.1–250 ppm. This could be attributed to the creation of a coordinative complex between ferric ions and phenolic tannic acid. The generated nanofibers were inspected by energy-dispersive X-ray (EDX) and scanning electron microscopy (SEM). The electrospun nanofibrous membrane showed an average diameter between 75 and 150 nm. The tannic acid-containing nanofibers are remarkably reusable and simple. The tannic acid-encapsulated polysulfone nanofibrous membrane was used to detect various metal ions, demonstrating a high selectivity for Fe3+. The ideal pH range for the identification of Fe3+ was determined to be in the range of 4.25–6.75.

Cell differentiation controls iron assimilation in a choanoflagellate.

Marine microeukaryotes have evolved diverse cellular features that link their life histories to surrounding environments. How those dynamic life histories intersect with the ecological functions of microeukaryotes remains a frontier to understand their roles in essential biogeochemical cycles1,2. Choanoflagellates, phagotrophs that cycle nutrients through filter feeding, provide models to explore this intersection, for many choanoflagellate species transition between life history stages by differentiating into distinct cell types3-6. Here we report that cell differentiation in the marine choanoflagellate Salpingoeca rosetta endows one of its cell types with the ability to utilize insoluble ferric colloids for improved growth through the expression of a cytochrome b561 iron reductase (cytb561a). This gene is an ortholog of the mammalian duodenal cytochrome b561 (DCYTB) that reduces ferric cations prior to their uptake in gut epithelia7 and is part of an iron utilization toolkit that choanoflagellates and their closest living relatives, the animals, inherited from a last common eukaryotic ancestor. In a database of oceanic metagenomes8,9, the abundance of cytb561a transcripts from choanoflagellates positively correlates with upwellings, which are a major source of ferric colloids in marine environments10. As this predominant form of iron11,12 is largely inaccessible to cell-walled microbes13,14, choanoflagellates and other phagotrophic eukaryotes may serve critical ecological roles by first acquiring ferric colloids through phagocytosis and then cycling this essential nutrient through iron utilization pathways13-15. These findings provide insight into the ecological roles choanoflagellates perform and inform reconstructions of early animal evolution where functionally distinct cell types became an integrated whole at the origin of animal multicellularity16-22.

Implementation of Three Gallium-Based Complexes in the "Trojan Horse" Antibacterial Strategy against A. baumannii: A DFT Approach.

Microorganisms of the ESKAPE group pose an enormous threat to human well-being, thus requiring a multidisciplinary approach for discovering novel drugs that are not only effective but utilize an innovative mechanism of action in order to decrease fast developing resistance. A promising but still hardly explored implementation in the "Trojan horse" antibacterial strategy has been recognized in gallium, an iron mimicry species with no known function but exerting a bacteriostatic/bactericidal effect against some representatives of the group. The study herewith focuses on the bacterium A. baumannii and its siderophore acinetobactin in its two isomeric forms depending on the acidity of the medium. By applying the powerful tools of the DFT approach, we aim to delineate those physicochemical characteristics that are of great importance for potentiating gallium's ability to compete with the native ferric cation for binding acinetobactin such as pH, solvent exposure (dielectric constant of the environment), different metal/siderophore ratios, and complex composition. Hence, the provided results not only furnish some explanation of the positive effect of three Ga3+-based anti-infectives in terms of metal cation competition but also shed light on reported in vitro and in vivo observations at a molecular level in regard to gallium's antibacterial effect against A. baumannii.

Yielding behaviour of chemically treated Pseudomonas fluorescens biofilms

The mechanics of biofilms are intrinsically shaped by their physicochemical environment. By understanding the influence of the extracellular matrix composition, pH and elevated levels of cationic species on the biofilm rheology, novel living materials with tuned properties can be formulated. In this study, we examine the role of a chaotropic agent (urea), two divalent cations and distilled deionized water on the nonlinear viscoelasticity of a model biofilm Pseudomonas fluorescens. The structural breakdown of each biofilm is quantified using tools of non-linear rheology. Our findings reveal that urea induced a softening response, and displayed strain overshoots comparable to distilled deionized water, without altering the microstructural packing fraction and macroscale morphology. The absorption of divalent ferrous and calcium cations into the biofilm matrix resulted in stiffening and a reduction in normalized elastic energy dissipation, accompanied by macroscale morphological wrinkling and moderate increases in the packing fraction. Notably, ferrous ions induced a predominance of rate dependent yielding, whereas the calcium ions resulted in equal contribution from both rate and strain dependent yielding and structural breakdown of the biofilms. Together, these results indicate that strain rate increasingly becomes an important factor controlling biofilm fluidity with cation-induced biofilm stiffening. The finding can help inform effective biofilm removal protocols and in development of bio-inks for additive manufacturing of biofilm derived materials.

Palladium doped PDA-coated hercynite as a highly efficient catalyst for mild hydrogenation of nitroareness

Hercynite magnetic nanoparticles were produced through the co-precipitation of ferrous and aluminum cations. The surface of hercynite was respectively coated with silica, 2,4,6-trichloro-1,3,5-triazine, and 1H-pyrazole-3,5-dicarboxylic acid to provide a suitable substrate for Pd(II) loading, furnishing Pd@Her-TCT-PDA. Subsequently, the introduced Pd(II) was reduced to Pd(0) using NaBH4. FT-IR, EDS, XRD, TGA, TEM and SEM images were the characteristic methods to prove the success of catalyst synthesis. The SEM image illustrated the particles with a nanosize of 25–50 nm and TEM image confirmed the presence of Pd nanoparticles with sizes lower than 2 nm. EDS elemental analysis of the catalyst proved the existence of Pd, Fe, and Al atoms along with the C, O, N, and Si atoms belong to the heterocyclic moieties. VSM analysis clarified a considerable drop in the magnetic properties of the hercynite core of the final catalyst due to its modified surface. TGA curve demonstrated that Pd@Her-TCT-PDA contains 20% organic content, attributed to the anchored heterocyclic ligands. Finally, Pd@Her-TCT-PDA was employed along with NaBH4 as a catalytic system to reduce completely the nitro group of aromatic compounds to their corresponding amines. The recyclability tests showed low drop in the catalytic activity of Pd@Her-TCT-PDA after third run with negligible leaching of Pd NPs.

Enhanced dielectric properties of co-substituted M-type Sr-La hexaferrite synthesized by citrate auto-combustion method

In this present research, comparative analysis of dielectric and electrical properties of M−type lanthanum-strontium (La-Sr) hexaferrites substituted with Co-Zr, Mn-Zr and Ni-Zr with chemical formulae: Sr0.85La0.15(CoZr)xFe12-2xO19, Sr0.85La0.15(MnZr)xFe12-2xO19 and Sr0.85La0.15(NiZr)xFe12-2xO19 (where x is 0.00 to 1.00 with ratio of 0.25) respectively have been investigated in 1 kHz to 1 MHz frequency range. The dielectric constant and loss tangent are generally shows decreasing trend with frequency and AC conductivity shows increasing trend with it. Dielectric constant, tangent loss and AC conductivity are increased with increase in substitution of Co-Zr and Mn-Zr doped La-Sr ferrites but shows opposite trend for Ni-Zr doped La-Sr hexaferrites. The higher electron exchange between ferrous cations (Fe2+) and ferric (Fe3+) cations are responsible for the higher polarization in ferrites. These newly synthesized ferrites have great potential for microwave absorbing material and microwave components

Synthesis and characterization of Fe3O4 core nanoparticles coated with TiO2 and ZnO

The room temperature synthesis of the core-shell-shell (CSS) nanoparticles was demonstrated to be green, low-cost, and reproducible. The magnetic core of Fe3O4 nanoparticles was coated with TiO2 and ZnO in two steps. The obtained CSS nanoparticles were extensively characterized by XPS, TEM, XRD, DRS-UV–vis, N2 Physisorption, Electromagnetic, and Raman spectroscopy. XPS analysis revealed that the magnetic core was successfully functionalized with the citric acid. The ratio between the ferric cations (Fe3+) and ferrous (Fe2+) is typically reported to be around two due to the presence of FeO and Fe2O3 to balance the charge in the structure. Nevertheless, XPS results demonstrated that the ratio resulted in higher stability than that of the crystal nominal structure, suggesting that the surface of the CSS is slightly enriched with Fe3+ cations. TEM results indicated an average core diameter of approximately 9±1 nm for Fe3O4 (M-US); the first shell exhibited an average thickness of 3±1 nm, while the ZnO second shell thickness resulted in around 2±1 nm. X-ray diffraction analysis identified inverse spinel, hematite, anatase, and zincite phases in M-US, MT, and MTZ, respectively. Notably, the MTZ sample also contained hematite in addition to inverse spinel. Diffuse Reflectance UV-Vis Spectroscopy results demonstrated a reduction in the band gap as the shell coverage varied. N2 adsorption-desorption isotherms indicated an increase in the surface area as the core nanoparticles were coated with the subsequent shells. Additionally, the coated samples presented a mesoporous structure with a maximum surface area of 110 m2g−1 for the MT material. Raman spectroscopy confirmed the presence of vibrational modes related to TiO2 and ZnO. The core-shell-shell nanoparticles presented suitable electronic properties to potentially be applied in the photodegradation of harmful compounds and azo dyes.

Thermodynamics of mantle minerals – III: the role of iron

SUMMARY We expand the scope of HeFESTo by encompassing the rich physics of iron in the mantle, including the existence of multiple valence and spin states. In our previous papers, we considered iron only in its most common state in the mantle: the high-spin divalent (ferrous) cation. We now add ferric iron end-members to six phases, as well as the three phases of native iron. We also add low-spin states of ferrous and ferric iron and capture the behaviour of the high-spin to low-spin transition. Consideration of the multi-state nature of iron, unique among the major elements, leads to developments of our theory, including generalization of the chemical potential to account for the possibility of multiple distinguishable states of iron co-existing on a single crystallographic site, the effect of the high-spin to low-spin transition on seismic wave velocities in multiphase systems, and computation of oxygen fugacity. Consideration of ferric iron also motivates the addition of the chromia component to several phases, so that we now consider the set of components: Ca, Na, Fe, Mg, Al, Si, O and Cr (CNFMASO+Cr). We present the results of a new global inversion of mineral properties and compare our results to experimental observations over the entire pressure–temperature range of the mantle and over a wide range of oxygen fugacity. Applications of our method illustrate how it might be used to better understand the seismic structure, dynamics and oxygen fugacity of the mantle.

Immobilization of natural extract from Humulus lupulus L. in electrospun polyvinyl alcohol nanofibrous membrane for colorimetric determination of ferric

Metallochromic nanofibrous membranes were electrospun from an aqueous solution of xanthohumol (XNS) of Humulus lupulus L. (common hop) extract and polyvinyl alcohol (PVA) for determination of ferric ions. In order to detect ferric ions in aquatic media, a simple, portable, quick, and colorimetric detector was prepared using xanthohumol chromophore as an active spectroscopic detection site encapsulated in PVA nanofibers as a hosting bulk. The CIE Lab color parameters show that binding these poisonous ferric cations to the xanthohumol active detection sites results in a noticeable color shift from yellow (467 nm) to off-white (337 nm). This could be attributed to the creation of a coordination bonds between Fe(III) and phenolic xanthohumol. Increasing the quantity of ferric ions was shown to have a linear effect on the monitored color. The xanthohumol extraction was investigated by High Performance Liquid Chromatography (HPLC). Energy-dispersive X-ray spectrometer (EDX) and scanning electron microscopy (SEM) were employed to characterize the surface morphologies and structural properties of XNS@PVA nanofibers. Electrospun XNS@PVA nanofibrous film with a nanofiber diameter of 75–225 nm was produced. In order to prepare water-insoluble nanofibers, they were exposed to cross-linking with glutaraldehyde fumes. The xanthohumol-containing nanofibers exhibit remarkable ease of use with a detection limit of 0.1–300 ppm. XNS@PVA exhibited high selectivity when compared to various transition metal ions, such as K+, Na+, Ba2+, Zn2+, Cd2+, Hg2+, Co2+, Mn2+, Cu2+, Mg2+, Ni2+, Ca2+, Al3+, and Cr3+. The optimized pH conditions for the detection of Fe(III) were shown to exist between the values of 5 and 7.75. When compared to alternative detection methods, the current assay has the advantages of rapidity, simplicity, cheapness, environmental safety, and ease of operation.

Investigating magnetic, and magneto-electric properties of Nd doped [(1-y) Bi1-xNdxFeO3-yPbTiO3] solid solution

Magneto-electronic devices applications of room-temperature multiferroics have been made possible by recent developments. But the potential use of pure BFO in multifunctional devices is constrained by its antiferromagnetic nature and need substitution-induced modification to improve magnetic and magnetoelectric properties. In the present paper, attempt has been made to improve the magnetic and magnetoelectric properties of the BiFeO3-PbTiO3 solid solution by incorporating Bismuth cation with Lead(II) ion and Ferric cation with Titanium cation into the formulation of Nd doped,(1-y)Bi1-xNdxFeO3-yPbTiO3where x = 0.05,0.10,0.15,0.20 and y = 0.1, 0.2,0.3 and 0.4. The impact of different PbTiO3 and Nd compositions on magnetoelectric and magnetic characteristics of solid solution has been investigated. The results showed that, degree of magnetization continuously increases with increasing Nd doping by affecting Fe-O-Fe angles. However, the magnetization drops as the volume of PbTiO3 rises, that may be attributed to a rise in the tetragonal phase of solid solutions. The improvement of the magnetoelectric coupling coefficient and change of antiferromagnetic behaviour to ferromagnetic behaviour of solid solutions has been observed with increasing Nd doping. This enhance the ferromagnetic behaviour of the compound.

Predicting Silicate Glass Geochemistry Using Raman Spectroscopy and Supervised Machine Learning: Partial Least Square Applications to Amorphous Raman Spectra.

Here, Raman spectroscopy is used to develop a univariate partial least squares (PLS) calibration capable of quantifying geochemistry in synthetic and natural silicate glass samples. The calibration yields eight oxide-specific models that allow predictions of silicon dioxide (SiO2), sodium oxide (Na2O), potassium oxide (K2O), calcium oxide (CaO), titanium dioxide (TiO2), aluminum oxide (Al2O3), ferrous oxide (FeOT), and magnesium oxide (MgO) (wt%) in glasses spanning a wide range of compositions, while also providing correlation-coefficient matrices that highlight the importance of specific Raman channels in the regression of a particular oxide. The PLS suite is trained on 48 of the 69 total glasses, and tested against 21 validation samples (i.e., held out of training). Trends in root mean square error of calibration (RMSEC), root mean square error of cross-validation (RMSECV), and root mean square error of prediction (RMSEP) model accuracy metrics are investigated to uncover the efficacy of utilizing multivariate analysis for such Raman data and are contextualized against recently produced strategies. The technique yields an average root mean of calibration (∼2.4 wt%), cross-validation (∼ 2.9 wt%), prediction (∼ 2.6 wt%), and normalized variance (∼ 28%). Raman band positional shifts are also mapped against underlying chemical variations; with major influences arising primarily as a function of overall oxidation state and silica concentration: via ferric cation (Fe3+)/ferrous cation (Fe2+) ratios and SiO2 (wt%). The algorithm is further validated preliminarily against a separate external set of 11 natural basaltic glasses to unravel the limitations of the synthetic models on natural samples, and to determine the suitability of "universal" Raman-model applications in scenarios where prior chemical contextualization of the target sample is possible. This study represents the first time Raman spectra of amorphous silicates have been paired with PLS, offering a foundation for future improvements utilizing these systems.

Adsorption isotherm and kinetic study of Bengkulu Kaolinite in removing ferrous cation by continuous operation

Iron is a chemical element that is found in groundwater that can be suspended in the form of ferrous cations. Iron presence that exceeds the threshold can cause detrimental effects such as piping corrosion, bad smells, and health problems. According to observations, groundwater in Sukarame, Bandar Lampung, has smells and colors that indicate iron metal contamination. Hence, it is necessary to research reducing the iron content. The method used in this research is the adsorption method using kaolin adsorbent that has been activated by physical activation at 700°C. The adsorption was conducted continuously with various reactor heights of 20 cm, 15 cm, and 10 cm. The results showed that the most significant reduction in efficiency was found in the adsorption using reactors with a height of 20 cm by 92%. The adsorption phenomenon using a reactor height of 20 cm followed the Langmuir isotherm model (R2 = 0.9255) with an adsorption capacity of 17.03 mg/g. The kinetic data correlated well with the pseudo-second-order equation (R2 = 0.9313). It can be concluded that kaolin adsorbent can reduce iron levels, in which the adsorption using reactors with a height of 20 cm is the most effective.

Synthesis, Antioxidant and Antituberculosis Evaluation of Eugenol Derivatives from Mannich Condensation

AbstractMannich bases are interesting class of molecules thanks to their various pharmacological properties. This paper presents the synthesis and characterization of eugenol derivatives following Mannich condensation. The in vitro antituberculosis activity of the synthesized derivatives was evaluated by the Resazurin microtiter assay (REMA). The 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical scavenging and ferrous cation (FeCl2) chelating tests were used to estimate the antioxidant capacity. All eugenol Mannich bases inhibited the Mycobacterium tuberculosis (Mtb) H37Rv growing. Those of 2‐dimethylaminomethyl‐6‐methoxy‐4‐propenylphenol (1) and 2‐methoxy‐4‐propenyl‐6‐pyrrolidinylmethylphenol (4) were the most active at 10 μg/mL. Additionally, significant antioxidant profile was exhibited by the synthesized derivatives, especially for 2‐dicyclohexylaminomethyl‐6‐methoxy‐4‐propenylphenol (5) that showed an antiradical activity of EC50=20 μg/mL, twice as strong as that of eugenol precursor, and for 2‐methoxy‐6‐methylpiperazinylmethyl‐4‐propenylphenol (3) and compound 4, which were promising iron chelators with EC50 of 0.016 and 0.018 mg/mL, respectively, better than EDTA standard. The molecular docking experiments on two different antituberculosis receptors showed excellent binding affinity of compounds 4 and 5 into the active site of pantothenate kinase (PanK, type I), suggesting PanK as potential molecular target. These encouraging findings showed the importance of Mannich reaction for the development of antitubercular candidates and the improvement of natural products bioactivity.

Development of novel iron(III) crosslinked bioinks comprising carboxymethyl cellulose, xanthan gum, and hyaluronic acid for soft tissue engineering applications.

The advent of three-dimensional (3D) bioprinting offers a feasible approach to construct complex structures for soft tissue regeneration. Carboxymethyl cellulose (CMC) has been emerging as a very promising biomaterial for 3D bioprinting. However, due to the inability to maintain the post-printed stability, CMC needs to be physically blended and/or chemically crosslinked with other polymers. In this context, this study presents the combination of CMC with xanthan gum (XG) and hyaluronic acid (HA) to formulate a multicomponent bioink, leveraging the printability of CMC and XG, as well as the cellular support properties of HA. The ionic crosslinking of printed constructs with iron(III) via the metal-ion coordination between ferric cations and carboxylate groups of the three polymers was introduced to induce improved mechanical strength and long-term stability. Moreover, immortalized human epidermal keratinocytes (HaCaT) and human foreskin fibroblasts (HFF) encapsulated within iron-crosslinked printed hydrogels exhibited excellent cell viability (more than 95%) and preserved morphology. Overall, the presented study highlights that the combination of these three biopolymers and the ionic crosslinking with ferric ions is a valuable strategy to be considered for the development of new and advanced hydrogel-based bioinks for soft tissue engineering applications.

(CN3H6)[FeIIFeIII(SO4)3(H2O)3]: A Framework Iron Sulfate with a Mixed S = 2 and S = 5/2 Honeycomb Lattice.

A new guanidinium-templated hydrated iron sulfate, [CN3H6][FeIIFeIII(SO4)3(H2O)3] (1), was prepared from strongly acidic aqueous solutions. Its crystal structure is comprised from FeIIIO6 and FeIIO3(H2O)3 octahedra linked by sulfate bridges forming a [FeIIFeII(SO4)3(H2O)3]- 3D framework with a layer-by-layer ordering of ferric and ferrous cations. The structural topology of the framework is related to the anhydrous rhombohedral mikasaite Fe2(SO4)3. The removal of part of the sulfate tetrahedra and the partial replacement of the Fe3+ cations in the [Fe3+2(SO4)3]0 framework by Fe2+ provide a negative charge and allow the incorporation of the protonated organic species in the voids. The compound 1 has been characterized by single-crystal X-ray diffraction, TG and DSC analyses, UV-vis-NIR spectroscopy, magnetic susceptibility, Mössbauer spectroscopy, IR and Raman spectroscopy, and density functional band-structure calculations. The magnetic behavior of 1 shows an interplay of FeII (S = 2) and FeIII (S = 5/2) sublattices that exhibit different types of antiferromagnetic couplings, one FeIII-FeIII (J1 ∼ 6.1 K) and two FeII-FeIII couplings (J2 ∼ 1 K, J3 ∼ 5.9 K) within corrugated honeycomb layers. These ferrimagnetic layers are coupled antiparallel to each other, resulting in an overall antiferromagnetic order below TN = 31 K.

Ferric ion-assisted assembly of MXene/TiO2-graphene aerogel for ionic liquid-based supercapacitors

To achieve pseudocapacitance by driving reversible redox reactions is scientifically appealing to realize high energy density of supercapacitors (SCs). In this work, a unique ferric ions-assisted self-assembly MXene/TiO2-graphene aerogel composite (MXene/TiO2-Fe-G) is developed. The MXene/TiO2-Fe-G composite has a 3D hierarchical porous framework, large accessible specific surface area, and amorphous TiO2 modified on the surface of MXene nanosheets. Importantly, amorphous TiO2, generated from the partial oxidation of MXene, can contribute enormous pseudocapacitance via the reversible redox reaction with Lithium ions. In addition, ferric cations with variable valence states can also provide pseudocapacitance. A trinary ionic liquid-based electrolyte (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide-acetonitrile-lithium bis(trifluoromethanesulfonyl)imide, EmimTFSI-ACN-LiTFSI) with a wide electrochemical stability potential window is also formulated to match the new material. Consequently, the MXene/TiO2-Fe-G composite as the negative electrode shows a superb specific capacitance of 196.4 F g−1 at 1 A g−1. An asymmetric supercapacitor assembled with the MXene/TiO2-Fe-G anode and self-synthesized nitrogen-doped reduced graphene oxide aerogel (N-RGA) cathode can deliver a high energy density of 54 Wh kg−1 at a high-power density of 1737 W kg−1. This work provides a possibility of implementing pseudocapacitance by changing the morphology and structure of MXene composites to match the ionic liquid-based electrolyte, which can considerably enhance the performance of MXene-based SCs.

Impact of catalyst, chelating agent and light irradiation on electro-Fenton performance under not optimal conditions.

Electro-Fenton is a promising game-changer for distributed wastewater treatments for the removal of recalcitrant compounds that it is possible to find in industrial effluent and looking for a water reuse approach. This electrochemical advanced oxidation process (EAOPs) is able to provide fast removal of organic compounds, like dyes, due to the in-situ H2O2 production and its reaction with Fe2+ to form hydroxyl radicals. The literature clearly reports that this reaction reaches its optimum in acid conditions (pH = 3) and low catalyst concentrations [Fe2+<0.5 mM]. This paper wants to investigate the effects of the shifting from optimal conditions on the removal of reactive black 5 (RB5), treating solutions which contain a higher amount of catalyst and a less acid pH. Textile effluents usually contain also other metals able to act as catalyst for Fenton reaction, like copper. Here its activity has been investigated as well as the possible synergistic effect with Fe2+. The results confirm that copper can enhance RB5 removal, especially in those conditions critical for ferrous cation. In the second part, possible process modifications to overcome the issues introduced by unfavourable operating conditions (pH > 3 and Fe2+ > 0.5 mM) are considered, such as the usage of a chelating agent (EDTA) and the application of a light source. The results show the positive impact of these two system modifications highlighting the possibility to enlarge the application window of electro-Fenton systems.

Degradation of pesticides by heterogeneous Fenton using iron-exchanged clays

The aim of this research is to study the feasibility of using low-cost and natural bentonite and kaolinite clays, compared with commercial bentonite, as raw materials to prepare catalysts for the removal of two emerging pollutants, the neonicotinoid pesticides nitenpyram and acetamiprid, by heterogeneous Fenton process. The raw materials were subjected to a simple ion exchange method to improve their textural properties using a solution containing ferric cations followed by calcination at 500 °C. Results show high activity for all the catalysts in the removal of these pesticides, Stability tests were carried out confirming the high stability of these materials.

Asbestos and Iron.

Theories of disease pathogenesis following asbestos exposure have focused on the participation of iron. After exposure, an open network of negatively charged functional groups on the fiber surface complexes host metals with a preference for iron. Competition for iron between the host and the asbestos results in a functional metal deficiency. The homeostasis of iron in the host is modified by the cell response, including increased import to correct the loss of the metal to the fiber surface. The biological effects of asbestos develop in response to and are associated with the disruption of iron homeostasis. Cell iron deficiency in the host following fiber exposure activates kinases and transcription factors, which are associated with the release of mediators coordinating both inflammatory and fibrotic responses. Relative to serpentine chrysotile, the clearance of amphiboles is incomplete, resulting in translocation to the mesothelial surface of the pleura. Since the biological effect of asbestos is dependent on retention of the fiber, the sequestration of iron by the surface, and functional iron deficiency in the cell, the greater clearance (i.e., decreased persistence) of chrysotile results in its diminished impact. An inability to clear asbestos from the lower respiratory tract initiates a host process of iron biomineralization (i.e., asbestos body formation). Host cells attempt to mobilize the metal sequestered by the fiber surface by producing superoxide at the phagosome membrane. The subsequent ferrous cation is oxidized and undergoes hydrolysis, creating poorly crystalline iron oxyhydroxide (i.e., ferrihydrite) included in the coat of the asbestos body.

Decoding the black essence of Melianthus nectar.

This article is a Commentary on Magner et al. (2023), 239: 2026–2040.