Search Results (91)

Proper joint function has a significant impact on people’s quality of life. Joints are the point of connection between two or more bones and consist of at least three elements: joint surfaces, the joint capsule, and the joint cavity. Joint diseases are a serious social problem. Risk factors for the development of these diseases include overweight and obesity, gender, and intestinal microbiome disorders. Another factor that is considered to influence joint diseases is trace elements. Under normal conditions, elements such as iron (Fe), copper (Cu), cobalt (Co), iodine (I), manganese (Mn), zinc (Zn), silver (Ag), cadmium (Cd), mercury (Hg), lead (Pb), nickel (Ni) selenium (Se), boron (B), and silicon (Si) are part of enzymes involved in reactions that determine the proper functioning of cells, regulate redox metabolism, and determine the maturation of cells that build joint components. However, when the normal concentration of the above-mentioned elements is disturbed and toxic elements are present, dangerous joint diseases can develop. In this article, we focus on the role of trace elements in joint function. We describe the molecular mechanisms that explain their interaction with chondrocytes, osteocytes, osteoblasts, osteoclasts, and synoviocytes, as well as their proliferation, apoptosis, and extracellular matrix synthesis. We also focus on the role of these trace elements in the pathogenesis of joint diseases: rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), ankylosing spondylitis (AS), and systemic lupus erythematosus (SLE). We describe the roles of increased or decreased concentrations of individual elements in the pathogenesis and development of joint diseases and their impact on inflammation and disease progression, referring to molecular mechanisms. We also discuss their potential application in the treatment of joint diseases. Full article

Hydrogen energy is a pivotal carrier for achieving carbon neutrality, requiring green and efficient production via water electrolysis. However, the anodic oxygen evolution reaction (OER) involves a sluggish four-electron transfer process, resulting in high overpotentials, while the prohibitive cost and complex preparation of precious metal catalysts impede large-scale commercialization. In this study, we develop a FeCo-based bimetallic deep eutectic solvent (FeCo-DES) as a multifunctional reaction medium for engineering a three-dimensional (3D) coral-like FeOOH-Co₂(OH)₃Cl/NF composite via a mild one-step impregnation approach (70 °C, ambient pressure). The FeCo-DES simultaneously serves as the solvent, metal source, and redox agent, driving the controlled in situ assembly of FeOOH-Co₂(OH)₃Cl hybrids on Ni(OH)₂/NiOOH-coated nickel foam (NF). This hierarchical architecture induces synergistic enhancement through geometric structural effects combined with multi-component electronic interactions. Consequently, the FeOOH-Co₂(OH)₃Cl/NF catalyst achieves a remarkably low overpotential of 197 mV at 100 mA cm⁻² and a Tafel slope of 65.9 mV dec⁻¹, along with 98% current retention over 24 h chronopotentiometry. This study pioneers a DES-mediated strategy for designing robust composite catalysts, establishing a scalable blueprint for high-performance and low-cost OER systems. Full article

The widespread contamination of aquatic environments by tetracycline antibiotics (TCs) poses a substantial threat to public health and ecosystem stability. Although photo-Fenton processes have demonstrated remarkable efficacy in degrading TCs, their practical application is limited by challenges associated with catalyst recyclability. This study reports the development of a novel magnetic recoverable SrFe₁₂O₁₉/g-C₃N₄ heterostructure photocatalyst synthesized via a facile one-step co-calcination method using industrial-grade precursors. Comprehensive characterization revealed that nitrogen defects and the formation of heterojunction structures significantly suppress electron (e⁻)–hole (h⁺) pair recombination, thereby markedly enhancing catalytic activity. The optimized 7-SFO/CN composite removes over 90% of oxytetracycline (OTC) within 60 min, achieving degradation rate constants of 0.0393 min⁻¹, which are 9.1 times higher than those of SrFe₁₂O₁₉ (0.0043 min⁻¹) and 4.2 times higher than those of g-C₃N₄ (0.0094 min⁻¹). The effectively separated e⁻ play three critical roles: (i) directly activating H₂O₂ to generate ·OH radicals, (ii) promoting the redox cycling of Fe²⁺/Fe³⁺ ions, and (iii) reducing dissolved oxygen to form ·O₂⁻ species. Concurrently, h⁺ directly oxidize OTC molecules through surface-mediated reactions. Furthermore, the 7-SFO/CN composite exhibits exceptional operational stability and applicability, offering a transformative approach for scalable photocatalytic water treatment systems. This work provides an effective strategy for designing efficient and recoverable photocatalysts for environmental remediation. Full article

Superdeep diamonds and their syngenetic inclusions are crucial for understanding Earth’s deep carbon cycle and slab–mantle redox dynamics. The origins of these diamonds, especially their links to iron (Fe) carbides and ferropericlase with varying Mg# [=Mg/(Mg+Fe)_at], however, remain elusive. In this study, we performed high pressure–temperature (P-T) experiments (10–16 GPa and 1200–1700 K) across cold-to-warm subduction zones using a multi-anvil press. The results reveal a stepwise Fe-mediated carbonate reduction process for the formation of superdeep diamonds: MgCO₃ → Fe-carbides (Fe₃C/Fe₇C₃) → graphite/diamond. This mechanism explains two phenomena regarding superdeep diamonds: (1) anomalous ¹³C depletion results from kinetic isotope fractionation during ¹²C enrichment into the intermediate Fe-carbides; (2) nitrogen scarcity is due to Fe-carbides acting as nitrogen sinks. Ferropericlase [(Mg,Fe)O] formed during the reactions in our experiments shows Mg# variations (0.2–0.9), similar to those found in natural samples. High Mg# (>0.7) variants from lower temperature experiments indicate diamond crystallization from carbonatitic melts in the shallow lower mantle, while the broad Mg# range (0.2–0.9) from experiments at higher temperatures suggests multi-depth formation processes as found in Brazilian diamonds. These findings suggest that slab–mantle interactions produce superdeep diamonds with distinctive Fe-carbides and ferropericlase assemblages as inclusions, coupled with their ¹³C- and nitrogen-depleted signatures, which underscore thermochemical carbon cycling as a key factor in deep carbon storage and mantle mineralogy. Full article

The Luhai uranium deposit is a large-scale uranium deposit newly discovered in recent years through comprehensive prospecting methods. It is located in the Basaiqi Paleochannel Uranium metallogenic belt of the Erlian Basin and is characterized by its shallow burial and large scale. This paper provides new data on the genetic processes of sandstone-type uranium mineralization through sedimentological and geochemical environmental indicators (such as Fe³⁺/Fe²⁺, organic carbon, total sulfur, etc.), analysis of C-O isotopes of carbonate cements and H-O isotopes of groundwater, and geochemical and mineralogical studies of uranium minerals, iron–titanium oxides (involving backscatter analysis, micro-area chemical composition determination, and elemental surface scanning), and organic matter. Sedimentological analysis shows that the ore- bearing layer in the upper member of the Saihan Formation developed a braided channel within floodplain subfacies, which control the distribution of uranium ore bodies. Uranium mineralogical observations, geochemical environmental indicators, and organic geochemical data indicate that the main reducing agents related to mineralization are pyrite, terrestrial plants, and deep-sourced oil and gas. The δD values of groundwater in the ore-bearing layer range from −95.34‰ to −90.68‰, and the δ¹⁸O values range from −12.24‰ to −11.87‰. For calcite cements, the δ¹⁸O_V-PDB values range from −24‰ to −11.5‰, and the δ¹⁸_OV-SMOW values range from 6.2‰ to 19‰. It was determined that the ore-forming fluid is mainly surface fresh water that entered the strata during the tectonic uplift stage, with local mixing of deep-sourced brine. Based on these data, the main modes of uranium mineralization in the paleochannel were obtained as follows: (1) Redox mineralization occurs due to the reducing medium within the sand body itself and the reduction caused by deep- sourced oil and gas generated from the Tengge’er and Arshan Formations. (2) Mineralization is achieved through the mixing of fluids from different sources. Furthermore, a genetic model related to uranium mineralization in the paleochannels of the Luhai area has been established: favorable uranium reservoirs were formed during the sedimentary period, and during the post-sedimentary stage, reverse structures promoted redox reactions and fluid-mixing-induced mineralization. The research findings can provide guidance for the exploration of paleochannel sandstone-type uranium deposits in other areas of the Erlian Basin. Full article

This study demonstrates, for the first time, the formation of a hemiester of carbonic acid on self-assembled monolayers using voltammetric techniques and redox probes. A gold electrode (GE) was modified with 2-mercaptoethanol (ME) through self-assembly. With this modified electrode (GE-ME), a well-defined peak was observed by differential pulse voltammetry (DPV) for the negatively charged redox probe, ferricyanide/ferrocyanide, [Fe(CN)₆]³⁻/⁴⁻, in sodium acetate as an electrolyte adjusted to pH 8.2. In the presence of dissolved CO₂ in equilibrium with bicarbonate, there is a decrease in the ferrocyanide peak current with time (~30% in 60 min), attributed to the formation of hemiester 2-mercapto ethyl carbonate at the GE-ME/solution interface. Similarly, dissolved CO₂ and bicarbonate also affect the electrochemical impedance measurements by increasing resistance to the charge transfer process with time (elevation of Rct values), compatible with the formation of the hemiester. The addition of barium salt led to the displacement of the equilibrium towards BaCO₃ precipitation and consequent dissociation of the hemiester, attested by the recovery of the initial ferricyanide DPV signal. With the positively charged redox probe [Ru(NH₃)₆]²⁺, no decrease in the DPV peak was observed during the formation of the hemiester by reaction with bicarbonate. The repulsion of [Fe(CN)₆]³⁻, but not of [Ru(NH3)₆]²⁺, suggests that the formed species is the negatively charged 2-mercapto-ethyl carbonate, i.e., the hemiester with a dissociated proton. Due to the lack of a voltammetric signal from the hemiester itself, the formation of a self-assembled layer of thio-alcohol followed by the gradual formation of the corresponding carbonic acid hemiester allowed us to reach an elegant way of electrochemically demonstrating the formation of these species. Full article

The chemical looping reforming of methane using an SrFeO₃ oxygen carrier to produce synthesis gas from solar energy was experimentally investigated and validated. High-temperature solar heat was used to provide the reaction enthalpy, and therefore the methane feedstock was entirely dedicated to producing syngas. The two-step isothermal process encompassed partial perovskite reduction with methane (partial oxidation of CH₄) and exothermic oxidation of SrFeO_3-δ with CO₂ or H₂O splitting under the same operating temperature. The oxygen carrier material was shaped in the form of a reticulated porous foam structure for enhancing heat and mass transfer, and it was cycled in a solar-heated tubular reactor under different operating parameters (temperature: 950–1050 °C, methane mole fraction: 5–30%, and type of oxidant gas: H₂O vs. CO₂). This study aimed to assess the fuel production capacity of the two-step process and to demonstrate the potential of using strontium ferrite perovskite during solar cycling for the first time. The maximum H₂ and CO production rates during CH₄-induced reduction were 70 and 25 mL/min at 1000 °C and 15% CH₄ mole fraction. The increase in both the cycle temperature and the methane mole fraction promoted the reduction step, thereby enhancing syngas yields up to 569 mL/g during reduction at 1000 °C under 30% CH₄ (778 mL/g including both cycle steps), and thus outperforming the performance of the benchmark ceria material. In contrast, the oxidation step was not significantly affected by the experimental conditions and the material’s redox performance was weakly dependent on the nature of the oxidizing gas. The syngas yield remained above 200 mL/g during the oxidation step either with H₂O or CO₂. Twelve successive redox cycles with stable patterns in the syngas production yields validated material stability. Combining concentrated solar energy and chemical looping reforming was shown to be a promising and sustainable pathway toward carbon-neutral solar fuels. Full article

This work presents a study of the redox properties of CeO₂ particles with (FeCeHS) and without (CeHS) Fe₂O₃ impregnation, as possible innovative catalysts for oxidation and combustion reactions as well as CO₂ activation. The topic, therefore, is part of a broader analysis of environmental catalysis, which aims to reduce the emissions of polluting substances and improve the exploitation of energy resources, with consequent progress in the eco-friendly field. Different laboratory techniques (Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Ultraviolet–Visible (UV-Vis), and Fourier Transform–Infrared (FT-IR) spectroscopies) point out that iron oxide is deposited on the surface of ceria, which maintains its lattice structure, although the particle morphology is slightly changed. Methanol and ethanol adsorption and conversion were evaluated on these catalysts by Temperature Programmed Surface Reaction (TPSR) and by in situ FT-IR spectroscopy of the probe redox properties, evidencing the formation of surface oxidized intermediates and combustion products. The FeCeHS catalyst demonstrates, in our reaction conditions, a good combustion activity in total oxidation of oxygenated molecules, hindering the formation of formaldehyde from methanol and reducing the quantity of CO produced by the partial oxidation reaction. A cooperative effect is suggested by the mixture of these two metals in the oxidation process. Full article

The ascorbic acid (AA) assay is a widely recognized tool for assessing the oxidation potential (OP) of atmospheric particulate matter (PM), including PM_2.5. OP quantified through the cell-free AA assay can be used to study the association between chemical properties and harmful biological effects, such as the degradation of AA in the lungs by PM sample. AA is oxidized and depleted in solutions containing redox-active species such as polycyclic aromatic hydrocarbon quinones and heavy metal ions (Cu²⁺ and Fe²⁺), which are potential PM components. The metal ions form a Werner-type complex with ligands; thus, the AA depletion rate changes with the co-existing ligands in the PM sample. However, how the coordination structure of the complexes affects the AA depletion rate is poorly understood. This study examined the impact of the Werner-type complex formation of Cu²⁺ and Fe²⁺ on the AA depletion rate. Cu²⁺ and Fe²⁺ complexes were prepared by mixing them with three ethyleneamine forms: ethylenediamine, diethylenetriamine, and triethylenetetramine. The AA depletion rate was determined by measuring the changes in absorbance at 265 nm in the reaction solutions. Results indicated that the AA depletion rates of Cu²⁺ and Fe²⁺ were suppressed by the formation of complexes, and the degree of suppression depended on the coordination number and stability constants of the ethyleneamines. Additionally, AA depletion rates decreased with decreasing oxidative reduction potential in the solutions and changes in the coordination structures of the metal ion complexes. These findings demonstrate that the formation of Werner-type complexes with Cu²⁺ and Fe²⁺ reduces the AA depletion rate. As the number of ligands coordinating to the metal ions increases, the ORP decreases, creating a reducing environment that suppresses the oxidation of AA. Full article

The conversion of NO_x and the yield of N₂O during NH₃-SCR-DeNO_x below 473 K over TiO₂-supported transition metal oxide catalysts with equal loading of 20 wt.-% decreases in the following order of the supported oxides: MnO_x > CuO_x > CoO_x > FeO_x > NiO_x > CeO_x. The storage capacity for NH₃, characterized by the acid site density of the catalyst, is not directly correlated with the catalytic activity. Rather, the temperature range for the reduction of the supported transition metal oxides as determined by TPR-H₂ is the main governing factor for high NH₃-SCR-DeNO_x activity, especially in the temperature range below 473 K. At the same time, oxidation temperature range and the density of Lewis acid sites govern the formation of N₂O. The decomposition of NH₄NO₃ as an intermediate in the NH₃-SCR-DeNO_x reaction is determined by the redox property of TMO-based catalysts, which further influences both the windows of the decomposition temperature and the yield of N₂O. The correlation between the redox properties and the activity for NH₃-SCR-DeNO_x was confirmed for a series of MnO_x-CeO_x/TiO₂-SiO₂ mixed transition metal oxide catalysts as a promising combination of the less active and more selective CeO_x with less selective and highly active MnO_x. The linear correlation between reduction temperature range and the NH₃-SCR-DeNO_x activity indicates that the found relation can be transferred to other supported transition metal-containing catalysts for low-temperature NH₃-SCR-DeNO_x. Full article

Chemical looping partial oxidation of methane (CLPOM) is a low energy consumption and environmentally friendly new technology that can generate syngas. The main challenge is to find suitable oxygen carriers, which should be highly active, stable, low cost, and eco-friendly. This study found that Fe₂SiO₄ had good reactivity in the CLPOM process. Thermodynamic calculations were carried out by FactSage8.1 to demonstrate the feasibility of Fe₂SiO₄ as an oxygen carrier for CLPOM. Fe₂SiO₄ was prepared by the direct ball milling method and the high-temperature solid-phase synthesis method. The reaction properties of Fe₂SiO₄ were investigated in the fixed bed reactor. The XRD and FTIR results indicate that Fe₂SiO₄ can be synthesized successfully through the high-temperature solid-phase synthesis method. The results of fixed bed experiments showed that when the reaction temperature was 980 °C and the reaction time was 28 min, the $X_{C{H}_4}$ reached 87%, and the $S_{H_2}$ and $S_{\mathit{CO}}$ were 70% and 71%, respectively. Subsequently, 20 redox cycle experiments were conducted under the optimal reaction conditions. The results showed that Fe₂SiO₄ exhibited good reactivity in the first two cycles, and as the reaction progressed, the reduced oxygen carrier could not regain the lattice oxygen, leading to a decline in cyclic performance. This study demonstrates that Fe₂SiO₄ can couple CO₂ and CH₄ to produce syngas and is conducive to reducing carbon emissions. Full article

Heterogeneous Mg-Fe oxide/biochar (MgFeO@BC) nanocomposites were synthesized by a co-precipitation method and used as biochar-based catalysts to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) removal. The optimal conditions for SMX degradation were examined as follows: pH 7.0, MgFeO@BC of 0.4 g/L, PMS concentration of 0.6 mM and SMX concentration of 10.0 mg/L at 25 ℃. In the MgFeO@BC/PMS system, the removal efficiency of SMX was 99.0% in water within 40 min under optimal conditions. In the MgFeO@BC/PMS system, the removal efficiencies of tetracycline (TC), cephalexin (CEX), ciprofloxacin (CIP), 4-chloro-3-methyl phenol (CMP) and SMX within 40 min are 95.3%, 98.4%, 98.2%, 97.5% and 99.0%, respectively. The radical quenching experiments and electron spin resonance (ESR) analysis suggested that both non-radical pathway and radical pathway advanced SMX degradation. SMX was oxidized by sulfate radicals (SO₄^•−), hydroxyl radicals (•OH) and singlet oxygen (¹O₂), and SO₄^•− acted as the main active species. MgFeO@BC exhibits a higher current density, and therefore, a higher electron migration rate and redox capacity. Due to the large number of available binding sites on the surface of MgFeO@BC and the low amount of ion leaching during the catalytic reaction, the system has good anti-interference ability and stability. Finally, the intermediates of SMX were detected. Full article

This study investigates the impact of kaolin and boehmite alumina binders on the synthesis, catalytic properties, and attrition resistance of a La_0.7Sr_0.3FeO₃ (LSF) perovskite catalyst designed for the chemical looping partial oxidation (CLPO) of methane to produce synthesis gas sustainably. The as-synthesized and used catalysts with varying kaolin and boehmite alumina contents (KB_(x,y)/LSF) were scrutinized by a variety of characterization methods, including XRD, FE-SEM/EDS, BET, TPD-NH₃, and TPD-O₂ techniques. The catalytic activity of the synthesized samples was tested at 800 to 900 °C in a fixed-bed reactor producing syngas through the CLPO process over the consecutive redox cycles. Additionally, the attrition resistance of the fresh and used catalyst samples was examined in a jet cup apparatus to assess their durability against the stresses induced by thermal shocks or changes in the crystal lattice caused by chemical reactions. The characterization results showed the pure perovskite crystal structure of KB_(x,y)/LSF catalysts demonstrating adequate oxygen adsorption capacity, effective coke mitigation capability, robust thermal stability, and resilience to agglomeration during repetitive redox cycles. Among the tested catalysts, KB_(25,15)/LSF was identified as the superior sample, as it could consistently produce syngas with a suitable H₂:CO molar ratio varying from 2 to 3 within ten redox cycles at 900 °C, with CH₄ conversion and CO selectivity values up to 64% and 87%, respectively. The synthesized catalysts demonstrated a logarithmic attrition pattern in the jet cup tests at room temperature, featuring high attrition resistance after the erosion of particle shape irregularities or weakly bound particles. Moreover, the KB_(25,15)/LSF catalyst used at 900 °C showed great resistance in the attrition test, warranting its endurance in the face of extraordinarily harsh conditions in fluidized bed reactors employed for the CLPO process. Full article

Plant secondary metabolites, including phenolics, represent a large quantity of organic material that enters soil and contributes to the formation of soil organic matter (SOM). The process of phenolics forming SOM remains poorly understood. One possible mechanism is oxidation of the phenolic compound catalyzed by redox active metals such as manganese (Mn) and iron (Fe) in soils. In this work, we report how three phenolic compounds react with a redox active environmentally relevant metal, Mn(IV). The reactions were monitored via nuclear magnetic resonance (NMR), high-performance liquid chromatography (HPLC), and direct CO₂ measurements. Using these techniques, we demonstrate that gallic acid reacts with Mn(IV) less efficiently than pyrogallol. The products of the gallic acid:Mn(IV) reaction are more oxidized than the products of the pyrogallol reaction. Gallic acid produces small molecules and releases CO₂, while pyrogallol produces a less oxidized product, likely a quinone, and releases less CO₂. Benzoic acid did not react with Mn(IV). This work provides a framework for how different classes of plant secondary metabolites may be degraded abiotically by redox active metals in soil. Full article

Herein, motivated by the excellent redox properties of rod-shaped ceria (CeO₂-NR), a series of TM/CeO₂ catalysts, employing the first-row 3d transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) as active metal phases, were comparatively assessed under identical synthesis and reaction conditions to decipher the role of active metal in the CO₂ hydrogenation process. Notably, a volcano-type dependence of CO₂ hydrogenation activity/selectivity was disclosed as a function of metal entity revealing a maximum for the Ni-based sample. Ni/CeO₂ is extremely active and fully selective to methane (Y_CH4 = 90.8% at 350 °C), followed by Co/CeO₂ (Y_CH4 = 45.2%), whereas the rest of the metals present an inferior performance. No straightforward relationship was disclosed between the CO₂ hydrogenation performance and the textural, structural, and redox properties, whereas, on the other hand, a volcano-shaped trend was established with the relative concentration of oxygen vacancies and partially reduced Ce³⁺ species. The observed trend is also perfectly aligned with the previously reported volcano-type dependence of atomic hydrogen adsorption energy and CO₂ activation as a function of 3d-orbital electron number, revealing the key role of intrinsic electronic features of each metal in conjunction to metal–support interactions. Full article