Search Results (13,774)

Tungsten is a critical metal for advanced industrial applications, yet its supply is challenged by the depletion of high-grade ores. This study presents a comprehensive optimization and mechanistic analysis of the alkaline fusion process for extracting tungsten from wolframite ((Fe,Mn)WO₄) using sodium carbonate (Na₂CO₃). Experimental investigations systematically evaluated the effects of alkali-to-ore ratio, reaction temperature (650–1000 °C), and reaction duration (30–270 min). Optimal conditions were established at a 2:1 Na₂CO₃-to-ore molar ratio, a reaction temperature of 750 °C, and a holding time of 30 min, achieving a tungsten extraction efficiency exceeding 99.9%. This represents a significant improvement in energy and process efficiency over conventional methods. A novel kinetic analysis reveals a two-stage reaction mechanism, transitioning from a slow, diffusion-controlled solid-state reaction (E_a = 243 kJ/mol) to a rapid, autocatalytic liquid-phase reaction (E_a = 212 kJ/mol) upon the formation of a Na₂WO₄–Na₂CO₃ eutectic above approximately 590 °C. The optimal temperature of 750 °C is rationalized as the point that ensures operation within this kinetically favorable liquid-phase regime. Furthermore, a thermochemical analysis of ore impurities indicates that silicon, lead, sulfur, and calcium are effectively sequestered into the slag phase as stable silicates, insoluble lead compounds, and sulfates, highlighting an intrinsic purification benefit. X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses confirmed minimal residual tungsten in the processed slag. This streamlined process, supported by a robust mechanistic understanding, reduces alkaline consumption, shortens reaction times, and maintains high yields, offering a sustainable and efficient pathway for leveraging declining wolframite resources. Full article

Fe-Ni-based alloys have attracted attention due to their potential for applications such as transmission line de-icing, where the core requirements include a Curie temperature near the freezing point and sufficient saturation magnetization. Accordingly, this study designed an Fe-29Ni-2Cr-1.5Mn (at.%) alloy with a Curie temperature around the freezing point, aiming to investigate the correlation between microstructural evolution and magnetic properties after cold rolling and annealing. The alloy was cold-rolled by 65% and subsequently annealed at 873 K for 0 to 60 min. The study reveals systematic evolutions in the alloy’s microstructure and magnetic properties. During the initial annealing stage, recovery substructures predominantly formed within the deformed grains, accompanied by a reduction in dislocation density and lattice constant. In the later annealing stage, the recrystallized fraction increased, although complete recrystallization was not achieved. Texture analysis indicates that the intensity of the Cube texture strengthened from 0.48 to 1.13. Correspondingly, the saturation magnetization and Curie temperature increased by approximately 9.76% and 10.25%, respectively, in the early annealing period, and then stabilized thereafter. The early-stage improvement in properties is likely related to stress relief and lattice distortion relaxation during the recovery stage. The calculated magnetocrystalline anisotropy constant of this alloy at 273 K is K₁ = 126 ± 18 J/m³, indicating that the <100> direction is its easy magnetization axis. This study provides insights into optimizing the magnetic properties of this alloy through controlled annealing. Full article

Based on the discrete element method (DEM), a sand particle contact force model and a motion model for the 3D sand printing (3DSP) process were developed. By accounting for the viscous support force and contact force between sand particles, and gravity acting on each individual sand particle, the displacement of sand particles was calculated, enabling the simulation of the 3DSP process using sand particle ensembles. Furthermore, the effects of the ratio of silica sand to ceramsite sand and the recoating speed on sand-recoating performances and mechanical properties were investigated. Irregularly shaped sand particles (primarily silica sand) were constructed via the multi-sphere filling method. The simulation was performed on a virtual sand-recoating device (180 mm in length, 100 mm in width, 70 mm in height) with reference to the EXONE S-MAX printer. Meanwhile, the EXONE S-MAX was utilized to print the bending samples for experimental validation. Simulation and experimental results indicate that as the ratio increases, the porosity first decreases and then increases, whereas mechanical properties exhibit an initial increase followed by a decrease. At a ratio of 3:7, the porosity reaches a minimum of 21.3%; correspondingly, the shear force of bonding bridges peaks at 908 mN, and the bending strength of specimens attains a maximum of 2.87 MPa. With the increasing recoating speed, the porosity rises consistently, while the shear force of bonding bridges and the bending strength of specimens first increase and then decrease, which is primarily attributed to the penetration behavior of the binder under capillary force. At a recoating speed of 160 mm·s⁻¹, the shear force of bonding bridges reaches its maximum, and the specimens achieve a maximum bending strength of 2.89 MPa. The simulation results are well-validated by the experiments. The DEM-based simulation method proposed in this study offers a practical and convenient tool for parameter optimization in 3DSP process. Full article

Arsenic (As) contamination in paddy soils poses a serious risk to rice safety and human health. To mitigate this issue, we developed a low-temperature, partially pyrolyzed Fe/Mn/Mg-modified biochar (FMM-BC) and evaluated its performance and mechanisms for remediating As-contaminated soil through a pakchoi–rice rotation pot experiment, aiming to reduce As accumulation in rice grains and pakchoi. The results indicated that FMM-BC application altered soil physicochemical properties and As speciation, reducing both water-soluble and bioavailable As and promoting its transformation from exchangeable to more stable organic-bound and residual fractions. Compared with the control, FMM-BC application reduced arsenic content in rice stems, leaves, and brown rice to 1.94 mg∙kg⁻¹, 5.24 mg∙kg⁻¹, and 1.21 mg∙kg⁻¹, respectively. In contrast, unmodified biochar (BC) increased As bioavailability and plant uptake, underscoring the importance of Fe/Mn/Mg modification. FMM-BC also enhanced the translocation of Fe, Mn, and Mg within rice plants, thereby modifying internal As transport dynamics and suppressing its accumulation in aboveground tissues. Under FMM-BC treatment, arsenic content in pakchoi stems and leaves decreased to 1.19 mg∙kg⁻¹ (vs. 1.96 mg∙kg⁻¹ in the control), and brown rice declined to 0.27 mg∙kg⁻¹ (vs. 1.49 mg∙kg⁻¹ in the control)—well below the national food safety threshold (0.35 mg∙kg⁻¹). These findings demonstrate that FMM-BC effectively stabilizes As in contaminated soils and reduces its transfer to edible plant parts, with Fe/Mn/Mg playing a key role in enhancing As immobilization and limiting its mobility within the soil–plant system. Full article

The aim of this study was to evaluate the effects of selenium (Se) biofortification on growth, biomass accumulation, and micronutrient composition of industrial hemp (Cannabis sativa L., cv. Finola) microgreens, with emphasis on Se uptake and its distribution among leaves, stems, and roots. Microgreens were subjected to four Se treatments (Se_0, Se_2, Se_4, and Se_6 µmol Se/L), and changes in morphological traits, micronutrient status (Mn, Fe, Cu, Zn), and Se accumulation were assessed. Selenium biofortification had a marked impact on plant morphology and biomass. Stem length decreased by 12–18% under Se treatments compared with the control, whereas root length increased slightly, particularly at Se_2 and Se_4 (up to +6%). Fresh industrial hemp microgreens biomass responded strongly to Se supply, with the highest stem, root, and total fresh mass recorded at Se_4—representing an increase of 15–22% relative to control plants. At the highest Se level (Se_6), biomass declined by approximately 10–14%, indicating potential growth inhibition at excessive Se concentrations. Micronutrient concentrations were significantly affected by Se. Leaf Mn increased from 152 mg kg⁻¹ at Se_0 to 175 mg kg⁻¹ at Se_6 (+15%), while leaf Zn decreased by 20–25% at higher Se exposure. Stems and roots showed similar antagonistic interactions, with Fe and Zn decreasing by up to 30% at elevated Se levels. Conversely, Mn in stems and roots increased with Se up to Se_4, reaching 400 mg kg⁻¹ in roots. Selenium accumulation exhibited a strong linear response to biofortification, with high coefficients of determination (R² = 0.9685–0.9943), confirming predictable and efficient Se uptake. Correlation analysis revealed strong positive associations among biomass-related traits and distinct interactions among micronutrients, especially the near-perfect correlation between Se and Cu in roots (r ≈ 0.99). Overall, industrial hemp microgreens demonstrate potential for selenium biofortification, provided that selenium application levels remain within safe dietary limits. Full article

Background: Catheter ablation is a validated treatment for ventricular arrhythmias (VA), but conventional radiofrequency (RF) energy may cause collateral injury due to non-selective thermal damage. Pulsed Field Ablation (PFA), a non-thermal modality based on irreversible electroporation, offers myocardial tissue selectivity and enhanced safety. While PFA is widely adopted for atrial arrhythmias’ ablation, its application in the ventricles remains an evolving frontier. Methods: We report a single-center experience using the Centauri PFA system integrated with a focal, contact-force sensing irrigated catheter (Tacticath™ SE, Abbott Laboratories, St. Paul, MN, USA) in four consecutive patients with drug-refractory VA. Two patients presented with frequent premature ventricular complexes (PVC) arising from the right and left ventricular outflow tract, respectively, while two had ischemic cardiomyopathy with recurrent scar-related ventricular tachycardia (VT). All procedures were guided by high-density mapping using the EnSite X system (Abbott Laboratories, St. Paul, MN, USA). Procedural safety, acute efficacy, and early follow-up outcomes were assessed. Results: All ablations achieved acute procedural success without complications. In both PVC cases, PFA led to immediate and complete suppression of ectopy, with a ≥95% reduction in arrhythmic burden at 12- and 9-months follow-up, respectively. In the VT cases, the arrhythmogenic substrate was effectively modified, rendering the clinical VT non-inducible. ICD interrogation during a 9-month follow-up showed complete absence of recurrent sustained VT. No coronary spasm, atrioventricular block, pericardial effusion, or other adverse events occurred. Conclusions: In this initial experience, focal PFA using a contact-force sensing catheter appeared feasible and effective for both focal and scar-related VA. This system provides an intuitive workflow similar to RF ablation. While our data suggest a favourable safety profile, larger studies are required to definitively confirm safety margins near critical structures. Full article

This study presents the fabrication of composite photoelectrodes containing halogenated phthalocyanines (F₁₆CuPc and MnPcCl) embedded in polymeric matrices of PEDOT:PSS (poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate)) and PLA (polylactic acid biopolymer). These composites were deposited on PET, palm leaf, and wheat bagasse recyclable substrates, and were morphologically characterized. The reflectance for F₁₆CuPc/PEDOT:PSS is less than 8.5%, and that for MnPcCl/PLA changes depending on the substrate, ranging between 10% and 40%. Additionally, in the case of F₁₆CuPc/PEDOT:PSS, the Kubelka–Munk band gap is 3.7 eV, and in the case of F₁₆CuPc/PEDOT:PSS, the band gap varied between 2.85 and 3.47 eV. The composites were evaluated as electrodes in bio-based sustainable devices, fabricated with commercially available paper towels used as an organic membrane separator. The palm-device showed the best performance throughout its charge and discharge cycle. The device improves its performance at high speeds and reaches its highest peak at 100 mV s⁻¹ with 3.14 × 10⁴ μA. On the other hand, the greatest thermal stability for the composites is for those deposited onto bagasse substrate, reaching up to 220 °C and 357 °C for F₁₆CuPc/PEDOT:PSS and MnPcCl/PLA, respectively. Also, these composites exhibit charge–discharge behavior when studied in bio-based sustainable devices and can be used as electrodes. Full article

The synthesis of Mn-TiO₂/TiO₂, together with its application as a photoanode for solar flow batteries (SFBs), is reported herein. Both the pure TiO₂ electrode and the Mn-TiO₂/TiO₂ based composite electrode were prepared using the sol–gel spin-coating technique. The incorporation of a Mn-TiO₂ layer led to the enhancement of the built-in electric field within the composite photoanode. This enhancement not only improved the light-harvesting capability of the photoanode but also suppressed the recombination of charge carriers, consequently enhancing the photocatalytic efficiency. Furthermore, the optimal annealing temperature and the optimum TiO₂ loading were systematically controlled and optimized to maximize the photoelectric conversion efficiency of the composite photoanode. Ultimately, the optimized Mn-TiO₂ composite photoanode was integrated into a monolithic solar flow battery. The results demonstrate that the battery’s photocharging current density reaches 300 μA·cm⁻². The photocharging current density was relatively increased by 150%. Full article

D-tagatose is a high-value, low-calorie sweetener that can be produced from dairy lactose via a two-step enzymatic route: lactose hydrolysis to galactose followed by galactose isomerization to tagatose. Here, we combined genomics, in silico structural analysis, and biochemical assays to evaluate the lactose-to-tagatose conversion potential of an Antarctic isolate, L47, identified as Ewingella americana (NCBI accession SAMN54554459). Genome mining revealed one L-arabinose isomerase gene (araA) and three β-galactosidase genes (bgaA, bglY, lacZ), an uncommon combination in a single bacterium. Recombinant AraA was produced in Escherichia coli and biochemically characterized, showing Mn²⁺ dependence and measurable D-galactose isomerization, reaching ~18% tagatose from 100 mM galactose after 48 h under the tested conditions. In contrast, the β-galactosidases were predominantly recovered as insoluble aggregates in E. coli; therefore, β-galactosidase activity was assessed using washed inclusion-body preparations. Under these conditions, BgaA displayed the most consistent o-NPG hydrolyzing activity, whereas BglY and LacZ did not yield reproducible activity. Overall, our results identify BgaA as the most tractable lactose-hydrolyzing candidate from L47 in the current workflow and indicate that AraA performance is the principal bottleneck toward an efficient lactose-to-tagatose process, motivating future optimization at the enzyme and process levels. Full article

Metal pollution from metallurgical emissions poses serious environmental and public health risks in Kazakhstan. A replicated pot-culture experiment (n = 4) in a completely randomized design under controlled phytotron conditions evaluated biomass production and metal accumulation in six crop and forage species, alfalfa (Medicago sativa), amaranth (Amaranthus spp.), corn (Zea mays), mustard (Brassica juncea), rapeseed (Brassica napus), and sunflower (Helianthus annuus); three ornamental species, purple coneflower (Echinacea purpurea), marigold (Tagetes spp., ‘Tiger Eyes’), and sweet alyssum (Lobularia maritima); and three native wild plants, greater burdock (Arctium lappa), horse sorrel (Rumex confertus), and mug wort (Artemisia vulgaris). Plants were grown in soils collected from the Qarmet industrial zone in Temirtau, central Kazakhstan. Initial soil analysis revealed substantial mixed-metal contamination, ranked as Mn > Ba > Zn > Sr > Cr > Pb > Cu > Ni > B > Co. Mn reached 1059 mg·kg⁻¹, ~50-fold higher than B (22.7 mg·kg⁻¹). Ba (620 mg·kg⁻¹) exceeded FAO/WHO limits sixfold, Zn (204 mg·kg⁻¹) surpassed the lower threshold, and Pb (41.6 mg·kg⁻¹) approached permissible levels, while Cr, Cu, Ni, Co, and Sr were lower. Biomass production varied markedly among species: corn and sunflower produced the highest shoot biomass (126.8 and 60.9 g·plant⁻¹), whereas horse sorrel had the greatest root biomass (54.4 g·plant⁻¹). Root-to-shoot ratios indicated shoot-oriented growth (>1–8) in most species, except horse sorrel and burdock (<1). Metal accumulation was strongly species-specific. Corn and marigold accumulated Co, Pb, Cr, Mn, Ni, Cu, B, and Ba but showed limited translocation (transfer function, TF < 0.5), whereas sunflower, amaranth, and mug wort exhibited moderate to high translocation (TF > 0.8 to <1) for selected metals. Corn is recommended for high-biomass metal removal, marigold for stabilization, sunflower, horse sorrel, and mug wort for multi-metal extraction, and amaranth and coneflower for targeted Co, Ni, and Cu translocation, supporting sustainable remediation of industrially contaminated soils. Full article

Background: Solid microneedles (MNs) are effective transdermal delivery devices but are commonly fabricated from metallic or non-biodegradable materials, raising concerns related to sustainability, waste management, and processing constraints. This study aimed to evaluate the suitability of the biodegradable biopolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBHVHHx) as a structuring material for solvent-free fabrication of solid MN arrays and to assess their mechanical performance, insertion capability, and drug delivery potential. Methods: PHBHVHHx MN arrays were fabricated by solvent-free micromolding at 200 °C. The resulting MNs were morphologically characterized by scanning electron microscopy. Mechanical properties were assessed by axial compression testing, and insertion performance was evaluated using a multilayer Parafilm skin simulant model. Diclofenac sodium was used as a model drug and applied via surface coating using a FucoPol-based formulation. In vitro drug release was assessed in phosphate-buffered saline under sink conditions and quantified by UV–Vis spectroscopy. Results: PHBHVHHx MN arrays consisted of sharp, well-defined conical needles (681 ± 45 µm length; 330 µm base diameter) with micro-textured surfaces. The MNs withstood compressive forces up to 0.25 ± 0.03 N/needle and achieved insertion depths of approximately 396 µm in the Parafilm model. Drug-coated MNs retained adequate mechanical integrity and exhibited a rapid release profile, with approximately 73% of diclofenac sodium released within 10 min. Conclusions: The results demonstrate that PHBHVHHx is a suitable biodegradable thermoplastic for the fabrication of solid MN arrays via a solvent-free process. PHBHVHHx MNs combine adequate mechanical performance, reliable insertion capability, and compatibility with coated drug delivery, supporting their potential as sustainable alternatives to conventional solid MN systems. Full article

The South Sakhalin mud volcano (Sakhalin Island, Russia) emits HCO₃-Cl/Na-Mg water, emanates CO₂ prevailing over CH₄ in the gas phase, and extrudes mud bearing five carbonate mineral species. The study focuses on the distribution, diversity, and origin of the carbonate minerals from the mud volcano (MV) ejecta, in terms of carbon cycle processes. The data presented include a synthesis of field observations, compositions of MV gases and waters, chemistry of carbonate minerals, as well as stable isotope geochemistry of MV waters (δ¹³С, δD, and δ¹⁸O) and carbonates (δ¹³С and δ¹⁸O). The sampled MV waters are isotopically heavy, with δ¹⁸O = +5.7 to +7.5 ‰ VSMOW, δD = −18.0 to −11.0 ‰ VSMOW, and ¹³С (δ¹³С_DIC = +6.9 to +8.1 ‰ VPDB). This composition may be due to the dilution of basinal water with dehydration water released during the diagenetic illitization of smectite. Carbonates in the sampled mud masses belong to three genetically different groups. Mg-rich siderite, (Fe_0.54–0.81Mg_0.04–0.30Ca_0.05–0.23Mn_0.00–0.08)CO₃, disseminated in abundance throughout the mud masses, coexists with common calcite and sporadic ankerite. The trace-element chemistry of Mg-siderite, as well as the oxygen (δ¹⁸O = +34.4 to +36.8 ‰ VSMOW) and carbon (δ¹³C = −1.3 to +0.6 ‰ VPDB) isotopic signatures, confirms its authigenic origin. Siderite formed during early diagenesis of the Upper Cretaceous sandy and clayey marine sediments mobilized by mud volcanism in the area. Another assemblage, composed of dawsonite, siderite, and vein calcite (±kaolinite), represents altered arkose sandstones found as few fragments in the mud. This assemblage may be a marker of later CO₂ flooding into the sandstone aquifer in the geological past. The trace-element chemistry, particular morphology, and heavy C (δ¹³С = +5.5 to +7.0 ‰ VPDB) and O (δ¹⁸О = +39.1 to +39.5 ‰ VSMOW) isotope compositions indicate that aragonite is the only carbonate species that is related to the current MV activity. It crystallized in a shallow reservoir and was maintained by СО₂ released from rapidly ascending liquefied mud and HCO₃-Cl/Na-Mg-type of MV waters. Full article

Background: The mirror neuron system (MNS) has been proposed as a key neural mechanism linking action perception, motor representation, and social cognition. This framework has increasingly been applied to pain research, encompassing pain empathy, observational learning of pain, and rehabilitative interventions such as mirror therapy. However, the literature is conceptually heterogeneous, methodologically diverse, and spans experimental, social, and clinical domains. Objective: This scoping review aims to map the extent, nature, and characteristics of the available evidence on the relationship between the MNS and pain, clarifying how MNS-related mechanisms are defined, investigated, and applied across different contexts. Methods: A scoping review was conducted using the methodological framework proposed by the Joanna Briggs Institute and reported in accordance with PRISMA-ScR guidelines. We searched PubMed/MEDLINE, Scopus, Web of Science, and PsycINFO. Studies were included if they addressed MNS-related mechanisms in pain processing, pain empathy, pain modulation, or pain rehabilitation. Eligible studies were charted and synthesized descriptively and thematically. Results: Twenty-one studies met the inclusion criteria. The evidence was predominantly derived from clinical and rehabilitative settings, with most studies focusing on mirror therapy or mirror visual feedback interventions. The majority of included populations consisting of adults with chronic pain conditions, particularly phantom limb pain and complex regional pain syndrome. Pain intensity, assessed mainly through self-reported clinical scales, was the most frequently reported outcome. A smaller number of studies investigated action observation or motor imagery paradigms, primarily in chronic musculoskeletal pain, showing short-term hypoalgesic effects. Across studies, substantial heterogeneity was observed in the conceptualization of MNS-related constructs, intervention protocols, outcome measures, and follow-up duration. Conclusions: Despite extensive theoretical discussion of the MNS, empirical applications are largely confined to clinical mirror-based interventions, with limited use of direct neurophysiological or neuroimaging markers. Since crucial conceptual and methodological gaps constrain comparability and translation into clinical practice, there is a need for clearer operational definitions and more integrated experimental and clinical research approaches. Full article

The development of efficient spinel oxide catalysts for low-temperature oxidation of volatile organic compounds (VOCs) remains an important research objective. In this work, Ru was doped into a CoMn₂O₄ spinel to enhance its catalytic activity toward toluene oxidation and the underlying promotion mechanism of Ru doping was systematically investigated. The resulting Ru-CoMn₂O₄ catalyst showed remarkable performance, with T₉₀ reaching approximately 224 °C at a WHSV of 60,000 cm³ g⁻¹ h⁻¹ and nearly 100% CO₂ selectivity above 200 °C. Mechanism studies revealed that the reaction followed both Mars–van Krevelen (MvK) and Eley–Rideal (E–R) pathways. The reaction rates were strongly influenced by the oxidizing capacity of the catalyst, the abundance of highly valent surface species (namely Co³⁺, Mn⁴⁺, and Ru⁴⁺), adsorbed toluene, lattice oxygen, gaseous toluene, and adsorbed oxygen. With Ru doping, new Ru–O–Mn and Ru–O–Co chains formed in the CoMn₂O₄ spinel structure, leading to a moderate enhancement in oxidizing ability and a moderate increase in the concentration of highly valent surface species, adsorbed toluene, and lattice oxygen. Although a slight reduction in adsorbed oxygen was observed, Ru doping significantly boosted the overall toluene oxidation activity of CoMn₂O₄. In summary, Ru-CoMn₂O₄ represented a promising catalyst for the efficient oxidation of VOCs. Full article

Natural rubber biosynthesis is catalyzed by a unilamella membrane-bound heterologous complex with multiple different subunits (rubber transferase, RTase). Two substrates and divalent metal cation activators are required, and their concentrations affect biosynthetic rate and polymer molecular weight. Rate, molecular weight, and complex stability are highly sensitive to Mg²⁺ and Mn²⁺ concentration, but studies are challenging because methods to control ion concentration may dislodge the elongating rubber polymers from the RTase complexes, halting synthesis and producing low-molecular-weight polymer. Here, programmable chemical actuators (PCAs) are used to electrochemically control rubber biosynthetic rate and subsequent molecular weight in enzymatically active rubber particles purified from Ficus elastica (Indian rubber tree). RTase activity was assayed using ³H-FPP (initiator) and ¹⁴C-IPP (monomer). Since only one FPP molecular is needed to initiate a new rubber polymer, the ratio of incorporated ³H-FPP to ¹⁴C-IPP was used to calculate the mean molecular weight of newly synthesized polymers. PCAs exchange ions in solution through REDOX reactions which we show control cation concentration without dislodging the elongating rubber polymers from the RTase. PCAs demonstrated highly tunable control over monomer incorporation and molecular weight in both Mg²⁺ and Mn²⁺ cations. REDOX cycling PCAs did not irreversibly inhibit the rubber transferase complex, and no indication of enzymatic damage was observed. Precise PCA control of RTase activity may pave the way for rubber eventually to be produced in bioreactors. Full article