Search Results (505)

Selenium nanoparticles (Se NPs) have shown potential for regulating cadmium (Cd) accumulation in rice; however, their particle-size-dependent effects in the paddy soil–rice system remain unclear. In this study, a whole-growth-period pot experiment was conducted to investigate the mechanisms of Se NPs with different particle sizes (50, 100, and 200 nm) applied at different rates (20 and 50 mg/kg) in regulating Cd accumulation in rice grown in Cd-contaminated paddy soil. Se NP application significantly altered rhizosphere pH and redox potential, decreased Cd concentrations in soil solution and DTPA-extractable Cd, and increased soil solution Se and KH₂PO₄-extractable Se. In the 20 mg/kg treatment, Se NPs promoted the transformation of Cd from exchangeable fractions to Fe–Mn oxide-bound fractions, indicating reduced Cd mobility. Se NPs also enhanced root iron plaque formation and increased the retention of Fe, Cd, and Se on the root surface. XPS analysis showed that 50 and 100 nm Se NPs increased the proportion of Fe(III) in root iron plaque, thereby strengthening Cd adsorption and immobilization at the root–soil interface. In addition, Se NP treatments reshaped rhizosphere microbial communities. The 50 nm treatment showed stronger effects on fungal taxa related to organic matter decomposition and Se activation, whereas the 100 nm treatment more effectively enriched bacterial groups associated with Fe and S cycling, including Thermodesulfobacteriota and Sideroxydans. Among all treatments, 100 nm Se NPs at 20 mg/kg reduced grain Cd from 0.466 to 0.050 mg/kg, representing an 89.27% reduction, while maintaining grain Se at 0.384 mg/kg, which is within the acceptable range for selenium-enriched rice. Overall, 100 nm Se NPs showed the best balance among Cd mitigation, Se biofortification, and ecological safety, suggesting their potential for application in safe rice production in Cd-contaminated paddy soils. Full article

Chiral salen-type metal complexes are promising for diverse applications, yet their crystals often exhibit complicated chiral behavior. We investigated the crystal structures of chlorine-substituted salen-type ligands incorporating a 1,2-diphenylethylenediamine moiety and their iron complexes, which revealed varied chiral phenomena. Synthesis of the ligands using (1S,2S)-, (1R,2R)-, and racemic starting amines exclusively produced racemic ligands. A similar racemization of the ligand was observed during the formation of a dinuclear oxidized Fe(III)-O-Fe(III) complex from FeSO₄·6H₂O (1). Conversely, complexation with FeCl₃ maintained the optically active (1S,2S)-configuration even in the iron(III) complex (2). To elucidate these structural features, intermolecular interactions were quantified via Hirshfeld surface analysis. Additionally, generative AI (Gemini, Google) was employed for data interpretation to discuss the correlation between the structural characteristics of chirality and Hirshfeld surface analysis. Full article

Progressive bladder fibrosis and impaired detrusor function represent converging pathological endpoints across diverse bladder disorders, including bladder outlet obstruction (BOO) associated with benign prostatic hyperplasia, spinal cord injury (SCI)-induced neurogenic bladder, radiation cystitis, and interstitial cystitis/bladder pain syndrome. Conventional therapies primarily manage symptoms and rarely reverse established fibrosis or restore durable bladder homeostasis. Mesenchymal stem/stromal cells (MSCs) have attracted considerable interest as therapeutic agents owing to their antifibrotic, immunomodulatory, angiogenic, and trophic paracrine activities. This review synthesises six key studies from our group and places them within the broader international literature on bladder regenerative medicine: (i) feasibility of superparamagnetic iron oxide (SPIO)-based molecular MRI tracking of transplanted human MSCs (hMSCs) in the bladder; (ii) SPIO-hMSC therapy for BOO-associated fibrosis with concurrent MRI monitoring; (iii) hepatocyte growth factor (HGF)-overexpressing engineered hMSC (B10.HGF) therapy in BOO; (iv) hMSC transplantation into the SCI-injured bladder wall monitored by MRI; (v) systematic review and meta-analysis of stem cell therapy effects on urodynamic outcomes in SCI models; and (vi) HGF-overexpressing hMSC therapy for BOO-induced underactive bladder. These six key studies are contextualised within the broader literature addressing cell sources, biomaterial-assisted delivery platforms, mechanistic pathways, emerging clinical evidence, and the evolving regulatory landscape for cell-based advanced therapy medicinal products. Key translational challenges include product standardisation, long-term durability, and mechanism-linked potency assay development. Full article

This case study investigates the ageing behaviour of hydroxyl-terminated polybutadiene (HTPB)-based solid propellants, containing 0.5% iron oxide and a bimodal ammonium perchlorate (AP) distribution (300 µm coarse AP and 40 µm fine AP). To achieve higher burning rates in large solid rocket motors, burning-rate catalysts were preferred over ultra-fine oxidiser compositions due to processing advantages. Characterisation of the iron oxide burning rate catalyst, specific to its surface area, was attempted. The role of surface characteristics in burning rate augmentation and ageing reactions was studied. Particle size and surface area estimates were obtained, and propellant burning rates, pressure exponents, and propellant ageing behaviour were evaluated to support the study. Accelerated thermal ageing of composite solid propellant samples at three different temperatures is carried out. The Arrhenius equation was used to model the dependence of the initial modulus on ageing time and temperature. An activation energy of 68.18 kJ/mole was obtained, which is approximately 4–8% lower than previously reported values for conventional propellants. The study concludes that iron oxide with a specific surface area of 10 m²/g and proportions up to 0.5% by weight can be safely used in propellant formulations without a significant reduction in the propellant’s shelf life. Full article

In this work, an ultrasonic relaxation spectroscopic study of aqueous ammonium Fe(II) sulfate, aqueous ammonium Fe(III) sulfate and the corresponding ternary system has been undertaken. A variety of acoustic parameters including relaxation frequency, relaxation amplitude and speed of sound were determined as a function of solution concentration. In addition, the adiabatic compressibility and the molar volume change during the ionic association in ammonium Fe(II) sulfate and ammonium Fe(III) sulfate aqueous solutions were also estimated from the acoustic data. This approach facilitated a comprehensive characterization of the three systems across different concentrations. In the two binary systems, the presence of an ion association mechanism was identified involving the divalent and trivalent iron ions, with the sulfate anions, respectively. Furthermore, in the ternary system, an internal sphere oxidation–reduction mechanism occurred between the divalent and trivalent iron ions. All ions within each solution play an active role in shaping the structure of water molecules, owing to the prevailing kosmotropic characteristics specific to each solution. The results are examined within the context of the current phenomenological understanding in the field. Full article

Soil salinization poses a significant global challenge to agriculture and the environment, leading to decreased soil fertility and hindered crop growth. Therefore, the development of effective and environmentally friendly soil improvement strategies is crucial for sustainable agriculture. In this study, a range of eco-friendly, versatile, and highly absorbent hydrogels for soil enhancement were created using itaconic acid (IA) as a hydrophilic monomer. Furthermore, their effectiveness and application in agriculture were thoroughly evaluated. The nano-iron-loaded IA-based hydrogels (nano-iron (III) oxide (nano-Fe₂O₃)/Poly itaconic acid (PIA)-Acrylamide (AM)/Sodium alginate (SA)) hydrogels demonstrated exceptional water absorption and retention capabilities. They exhibited remarkable soil conditioning properties by leveraging carboxyl groups for electrostatic adsorption of saline ions and the porous structure created by the crosslinked network. These features not only significantly facilitated gradual regulation of pH levels and salinity but also effectively enhanced organic matter in saline–alkali soil. Meanwhile, nano-Fe₂O₃ simultaneously served to stabilize the hydrogel structure and enhance crop nutrient absorption. Wheat cultivation trials demonstrated that the hydrogels notably enhanced the growth of 7-day-old wheat seedlings. The degradation rates of the hydrogels can be adjusted by varying the IA amount, allowing for the continuous release of small organic molecules to enhance soil quality, aligning with various crop growth cycles. Overall, these hydrogels function as environmentally friendly and versatile soil conditioners, offering significant potential for enhancing agricultural soil quality and expanding into related fields. Full article

Petroleum hydrocarbons contamination in soil is difficult to remediate due to strong adsorption and limited bioavailability. This study investigated the coupled remediation of diesel contamination in an alkaline kaolin-based model substrate using a silica gel-loaded, iron-catalyzed sodium percarbonate composite (SPC^SF) and Bacillus subtilis. The alkaline model substrate was used as a simplified representation of difficult-to-reclaim hydrocarbon- and reagent-impacted matrices that may occur at oil drilling or production sites. In this study, a combined remediation strategy integrating a silica gel-loaded, iron-catalyzed sodium percarbonate composite (SPC^SF) with Bacillus subtilis ATCC 11774 was developed for diesel-contaminated soil. The remediation performance of chemical oxidation, microbial remediation, and their combined application was systematically evaluated. The simultaneous SPC^SF–microbial treatment achieved the highest removal efficiency, reaching 65.1% after 31 d, which was markedly higher than that of chemical oxidation (22.5%) or microbial remediation alone (31.1%). Within the mineral model substrate used in this study, SPC^SF effectively regulated pH and oxidation–reduction potential, creating conditions more favorable for microbial activity. Spectroscopic analyses (three-dimensional fluorescence spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy) indicated that SPC^SF promoted the transformation of diesel hydrocarbons into bioavailable intermediates, which were further converted by microorganisms into carboxyl-rich organic matter. Bacillus subtilis was associated with a higher Fe(II) proportion in the coupled system, which may have favored maintenance of Fe redox activity and sustained Fenton-like reactivity. However, direct measurements of reactive oxygen species and Fe(II)/Fe(III) dynamics were not performed; therefore, this interpretation should be regarded as a plausible hypothesis based on indirect evidence. The specific microbial contribution to Fe redox transformation was inferred from indirect evidence and may also have been influenced by medium-derived components or microbial metabolites. This study presents a coupled supported sodium percarbonate and microbial remediation strategy providing mechanistic evidence for the compatibility of supported chemical oxidation and microbial degradation in diesel-contaminated soil. Full article

In this study, polyhedral self-assembled spherical titania (TS) photocatalyst was successfully synthesized via a one-step hydrothermal method from titanium chloride, sodium dodecyl sulfate and sulfuric acid. Titania modification with iron was carried out through the same procedure by the addition of different amounts of iron(III) chloride to the substrate mixture. Various methods were applied for sample characterization, e.g., XRD, SEM, TEM, XPS, UV-vis DRS, and photo-electrochemical measurements, such as EIS, CV, transient photocurrent, whereas photocatalytic activity was investigated for hydrogen evolution under UV/vis and oxidative decomposition of antibiotics under UV and/or vis, including also tests with scavengers. It has been found that iron was both incorporated in the titania structure (doping) and adsorbed on its surface. Although iron presence has hardly influenced the properties (slight changes in morphology, bandgap energy, and crystallite size), the photocatalytic activity has increased significantly. Therefore, it is proposed that iron might work as an electron sink, hindering the charge carriers’ recombination. Linear evolution of hydrogen, recycling experiments and characterization of samples after recycling have confirmed a good stability of iron-modified titania. Full article

The identification of the chemical species responsible for the anomalous near-ultraviolet (UV) opacity in the Venusian cloud for “unknown absorber” remains a paramount challenge in planetary science. This study presents a comprehensive quantum chemical investigation into a broad suite of candidate molecules, including isomers of thiosulfeno (S₂O₂), the hydroxysulfonyl radical (HSO₃), disulfur monoxide (S₂O), disulfur dichloride (S₂Cl₂), iron(III) chloride (FeCl₃), phosphine (PH₃), and structural isomers of polysulfur oxides (S₃O). Utilizing Time-Dependent Density Functional Theory (TD-DFT) at the CAM-B3LYP/def2-TZVPP level of theory, we systematically mapped electronic transitions across three distinct environmental phases: gas-phase (without solvent), supercritical CO₂, and concentrated H₂SO₄ aerosols. To establish confidence in the predicted results, our TD-DFT approach was rigorously benchmarked against high-level theoretical methods (CCSD(T), EOM-CCSD, and MRCI+Q) from recent literature. All these electronic transitions were modeled via the Solvation Model based on Density (SMD). Our results demonstrate a profound topological and environmental dependence on spectral signatures. Among the candidates, trans-OSSO (t-OSSO) emerged as the most viable near-UV absorber candidate, exhibiting a highly allowed π → π* transition at 379.37 nm (f = 0.1140) in H₂SO₄, providing a near-perfect alignment with the observed 365 nm planetary albedo drop. Conversely, the polysulfur oxide cis-S₃O was acknowledged as a primary visible-light chromophore, with an intense absorption at 436.31 nm (f = 0.1280) responsible for the characteristic yellow tint of the planet. Additionally, the photochemically maintained SSCl₂ isomer was identified as a critical broadband near-UV absorber. Species such as S₂O and planar S₃O were found to function as critical mid-UV shields (270–300 nm). This work establishes a multi-chromophore model of the Venusian atmosphere, where a chemically stratified network of sulfur-oxygen chains and chlorine-sulfur reservoirs, tuned by the acidic aerosol matrix, collectively governs radiative balance and atmospheric super-rotation of the planet. Furthermore, to account for massive continuum tailing into the visible region (>400 nm), we employed a semi-classical Reflection Principle approach to model 1D vibronic broadening. This analysis revealed that while standard solvent effects induce minor solvatochromic shifts, ground-state structural fluxionality in the OSSO isomers drives intense, symmetry-allowed transitions deep into the visible spectrum, an effect absent in structurally constrained or rigid control species. Full article

Iron-exchanged bentonites derived from a natural montmorillonite-rich clay (Taganskoe deposit, Kazakhstan) were prepared through a simple aqueous ion-exchange route using Fe(II) or Fe(III) inorganic salt precursors, yielding final Fe contents of ca. 5–7 wt.%, while preserving the smectite layered framework. A mild thermal treatment under air was applied to tune iron coordination without triggering major structural collapse. The resulting materials were characterized by ED-XRF, PXRD, FE-SEM/EDX, DLS/ζ-potential and DR UV–Vis–NIR spectroscopy, revealing predominantly exchanged Fe species with a limited fraction of surface iron-oxide clusters, whose contribution increases after activation. Structure–reactivity relationships were probed under mild conditions in liquid-phase ethyl acetate using dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethyl sulfide (2-CEES) as organophosphorus and organosulfur hazardous chemicals and chemical warfare agent simulants, respectively. Fe(III)-bentonite enabled very fast DMMP removal (ca. 93% within 0.5 h) with a remarkable improved performance with respect to Fe(II)-bentonite and the pristine mineral clay. For 2-CEES, the presence of H₂O₂ markedly enhanced oxidation on Fe-containing clays, reaching quantitative abatement within 24 h (up to >90%), with strong retention of oxidized sulfur products by the clay matrix. These results highlight Fe-exchanged natural bentonites as robust, cheap and multifunctional adsorption/catalytic solids for decontamination and water-treatment applications. Full article

Shallow-water hydrothermal systems in active volcanic arcs serve as natural analogs for geothermal reservoir characterization and potential sources of Critical Raw Materials (CRMs). This study examines the Panarea hydrothermal system (Aeolian Islands, Tyrrhenian Sea, 37–207 m depth) to characterize its mineralogical facies and assess CRM enrichment patterns. Sixteen sediment samples collected during 2013–2015 research cruises were analyzed using SEM-EDS, XRPD with Rietveld refinement, and XRF. Four hydrothermal alteration facies were identified: (i) a low-temperature iron oxide facies dominated by nanocrystalline goethite with enrichments in As, V, and Mo; (ii) an argillic to propylitic facies containing smectite-group clays and high-temperature silica polymorphs, consistent with alteration at 200–350 °C; (iii) a phyllic to propylitic facies showing exceptional Ba enrichment (up to 46,976 ppm) and base-metal sulfide accumulations; and (iv) an advanced argillic facies including the first documented aluminophosphate–sulfate mineral at Panarea, a svanbergite–woodhouseite solid solution. Vanadium concentrations at Panarea exceed values reported across the Tyrrhenian–Aeolian domain, ranking this site among the highest-V shallow hydrothermal fields in the Mediterranean. These findings support a genetic model involving fault-controlled seawater circulation, magmatic CO₂ input, and episodic redox fluctuations, providing baseline data for CRM cycling and geothermal evaluation in Mediterranean submarine volcanic systems. Full article

The paper describes the preparation of silver-containing nanocomposites by thermolysis of silver cinnamate and their application for the manufacture of reactive indicator paper (RIP) sensitive to iodine. The composition, structure, and properties of the obtained materials were studied using IR spectroscopy, X-ray diffraction, the gravimetric analysis method, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Optimal conditions for modifying a cellulose carrier with nanocomposites in laboratory conditions were selected, ensuring high sensitivity of RIP to iodine and uniform and reproducible distribution of the reagent. A new gas extraction colorimetric technique for determining iodide ions in the range of 0.03–1.6 mg L⁻¹ (limit of detection 0.01 mg L⁻¹) was developed, allowing iodides to be determined in multicomponent objects such as food products, pharmaceuticals, and various water bodies with minimized sample preparation. The use of iron(III) as an oxidizing agent and the use of dynamic gas extraction ensure high selectivity and good analytical performance. Full article

Ferrate(VI) has increasingly been proposed as an environmentally friendly oxidant due to its high reactivity and the relatively low toxicity of its by-products. However, its performance in degrading emerging pollutants (EPs) has not been systematically compared with conventional systems. This study presents a novel comparative assessment of three oxidation systems for the degradation of acetaminophen (APAP): (i) Fe⁰-activated hydrogen peroxide (HP), (ii) Fe⁰-activated persulfate (PS), and (iii) a commercial ferrate(VI)-based product, Envifer^® (Fe(VI)). Optimal conditions were determined based on degradation kinetics, pH dependence, and oxidant stability. Oxidant systems were then evaluated in realistic matrices, including tap water and synthetic wastewater. When UP water was used, the HP/Fe⁰ system achieved the highest APAP mineralization (i.e., 66%) with 1 mM of oxidant dosage, and PS/Fe⁰ was shown to be effective without pH adjustment. Nevertheless, these heterogeneous systems presented serious limitations when applied in more complex matrices. Fe(VI) instead achieved a rapid APAP degradation even in the presence of carbonates and natural organic matter without pH adjustment. This represents a key advantage over HP- and PS-based systems, enabling simpler implementation and lower chemical demand. Furthermore, Fe(VI) resulted in lower dissolved iron concentrations, potentially enabling less intensive post-treatment requirements. Overall, the results identify Fe(VI)-based AOPs as a potentially green alternative to conventional systems for wastewater treatment. Full article

Arsenic (As) contamination in groundwater represents a critical global environmental health issue. The reductive dissolution of arsenic-bearing iron oxides by dissimilatory metal-reducing bacteria (DMRB) is a key biogeochemical process driving arsenic mobilization and release in groundwater. However, the mechanism of exogenous electron shuttles in this process remains poorly understood. This study investigated the impact of the quinone-based electron shuttle anthraquinone-2,6-disulfonate (AQDS) on the reductive dissolution of arsenic-loaded goethite by the model DMRB Shewanella putrefaciens CN32 (S.P CN32). The mobilization and transformation behaviors of arsenic and iron were compared under different pH conditions and using different arsenic-loading methods (coprecipitation vs. adsorption). Results demonstrated that AQDS acted as an electron transfer mediator. It significantly enhanced the reductive dissolution of Fe(III). It also significantly enhanced the reduction of As(V). These actions collectively accelerated arsenic release and mobilization. The study also revealed a competitive preferential order in microbial reduction, where the thermodynamically more favorable Fe(III) reduction preceded As(V) reduction. Environmental pH co-regulated this process. Its influence worked through microbial activity and mineral surface properties. A neutral pH was most conducive to the AQDS-mediated bioreduction of arsenic and iron. This study elucidates the critical role of electron shuttles in the biogeochemical cycling of arsenic in contaminated sites, providing a scientific basis for a deeper understanding of the formation mechanisms and risk assessment of high-arsenic groundwater. Full article

To further understand redox mechanisms occurring in wine, caffeic acid (CAF, 150 mg/L) and/or glutathione (GSH, 150 mg/L) were added to a model wine solution, followed by ferric iron (2 mg/L Fe(III), added as 10 mg/L Fe(III) chloride hexahydrate), while monitoring the oxidation–reduction potential (ORP, redox potential). Caffeic acid produced only modest ORP changes. In contrast, glutathione and caffeic acid + glutathione additions dropped the ORP from 243 mV and 238 mV, respectively, to the same post-addition value of 189 mV, suggesting that glutathione dictated the ORP, while caffeic acid showed no effect. The quinone of caffeic acid (assumed as changes in AU at 420 nm), was not detected, suggesting caffeic acid did not participate in oxidation reactions under wine conditions under superfluous amounts of dissolved oxygen (DO). After the addition of Fe(III), ORP increased to similar values across all treatments: 266 mV (FE), 269 mV (CAF), 284 mV (GSH), and 242 mV (CAF + GSH), suggesting that the Fe(II)/Fe(III) redox couple dominated the ORP electrode response. CAF + GSH produced the steepest ORP decline after the addition of Fe(III) chloride hexahydrate (β (slope of the ORP) = −0.7082), significantly steeper than FE (β = −0.3051; p = 0.0032) and GSH (β = −0.4643; p = 0.0496), suggesting synergistic radical quenching and metal redox cycling. Photo-Fenton-like reactions likely contributed to slight decreases in the ORP over time. In conclusion, glutathione strongly lowered the ORP, Fe(III) increased the ORP across treatments, and caffeic acid had minimal impact on the ORP under model wine conditions. Full article