Search Results (512)

Quantum chemical modeling of the formation of active sites in 1,3-butadiene polymerization in the presence of neodymium Ziegler–Natta catalysts at the ONIOM (PBE0/def2–TZVP//GFN1-xTB) level was performed. The influence of chloride ion content and methylaluminoxane (MAO) used as a modifier on catalyst activity was studied. It was found that the use of MAO leads to an enhancement in the coordination interaction between the active site and the monomer. Thermodynamic analysis showed that the formation of active sites modified with MAO is more energetically favorable for less chlorinated structures. It was also found that the effect of MAO leads to the formation of complexes capable of exhibiting catalytic activity even in the absence of chloride ions, while their excess, conversely, leads to the displacement of MAO from the active sites. The stages of polymer chain initiation and growth under the action of MAO-modified neodymium Ziegler–Natta catalysts were studied as well. It was shown that the introduction of methylaluminoxane into the catalytic system leads to a decrease in the activation energy of monomer addition to the growing polymer chain and a reduction in the Gibbs free energy of reaction product formation. Full article

Hepatocellular carcinoma (HCC) is characterized by a poor prognosis, largely driven by metastasis and therapy resistance, processes closely linked to epithelial–mesenchymal transition (EMT) and ferroptosis. Neodymium nitrate (Nd(NO₃)₃), a predominant neodymium species, has shown antitumor potential, yet its specific effects and underlying mechanisms in HCC remain poorly understood. This study investigated whether Nd(NO₃)₃ exerts anti-malignant effects in Hep-G2 cells through the Nrf2–ferroptosis axis. We treated Hep-G2 cells with Nd(NO₃)₃ and assessed proliferation (CCK-8), migration, invasion (wound-healing and Transwell assays), EMT markers (E-cadherin, Vimentin), Nrf2 and GPx4 expression (Western blotting, qRT-PCR), and ferroptosis indicators (ROS, MDA, GSH, Fe²⁺/Fe³⁺). Low-dose Nd(NO₃)₃ significantly inhibited migration, invasion, and EMT-associated marker expression without affecting proliferation and promoted ferroptotic phenotypes, as evidenced by elevated ROS, MDA, and ferrous iron expression; decreased GSH levels; and downregulated GPx4 expression. Mechanistically, Nd(NO₃)₃ downregulated Nrf2 expression. Nrf2 overexpression reversed the suppression of migration, invasion, EMT-associated markers, and ferroptotic phenotypes, while the ferroptosis inhibitor deferoxamine rescued migration and invasion. These findings suggest that Nd(NO₃)₃ exerts anti-malignant effects in Hep-G2 cells by targeting Nrf2 to coordinately suppress EMT and promote ferroptosis, identifying the Nrf2–ferroptosis axis as a potential therapeutic target in HCC cells. However, these findings are based on in vitro experiments in a single Hep-G2 cell line with n = 3 biological replicates, which limits statistical power and generalizability; the results should therefore be interpreted as preliminary evidence requiring further validation in additional cell lines and in vivo models. Full article

Molten salt electrolysis is the primary industrial method for neodymium production, generating large volumes electrolyte crust after prolonged operation. However, the hazardous characteristics and environmental risks of this crust remain insufficiently characterized, which may hinder its proper environmental management and resource recovery. This study systematically analyzed the elemental composition, organic residues, and hazardous characteristics of electrolyte crust using XRF, XRD, XPS, and GC-MS, supplemented by standardized tests conducted in accordance with Chinese national standards GB 5085.1, GB 5085.3–GB 5085.6-2007 and HJ 298-2019. No VOC or SVOC residues were detected. Hazard characteristic tests confirmed that the electrolyte crust did not exhibit ignitability, corrosivity, reactivity, leaching toxicity or other tested hazardous characteristics. The calculated acute toxicity estimate (ATE) did not indicate a significant acute toxicity potential. These findings provide experimental and theoretical support for the environment risk evaluation and resource recovery of rare earth electrolytic solid wastes. Full article

The growing demand for electric vehicles has increased the need for rare earth elements (REEs), promoting the recycling of secondary sources such as end-of-life NdFeB permanent magnets. However, the selective separation of REEs with similar chemical properties, such as neodymium (Nd) and holmium (Ho), remains a major challenge. In this work, their separation from a real NdFeB permanent magnet leachate was investigated by liquid–liquid extraction using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an extractant. The effects of extractant concentration (0.05 M and 0.1 M), organic-to-aqueous phase ratio (1:1 and 2:1, O:A), and pH (0.6 and 2) on the extraction process were evaluated. Increasing extractant concentration and phase ratio improved Ho extraction, reaching above 90%, whereas Nd co-extraction remained relatively low at pH 0.6 (0.8–4.6%, depending on the conditions). However, pH was found to be the key parameter. At pH 2, Ho extraction exceeded 96% in all cases, while Nd co-extraction increased significantly (up to ~28%), reducing selectivity. Due to the high initial Nd:Ho concentration ratio (~12:1), even low Nd co-extraction percentages resulted in significant contamination of Ho-rich products, identifying product purity as the primary limiting factor. These results show a trade-off between recovery and selectivity, with low pH favoring selectivity and high pH favoring extraction efficiency. Full article

Incorporating energy generated from regular human movement into wearable electronics offers a promising alternative to conventional batteries, enabling devices to power themselves by harvesting energy from motion and the surrounding environment. Ambient energy harvesting provides a pathway toward limitless, self-sustaining power and supports the development of cleaner, smarter wearable systems. Among various approaches, integrating hybrid mechanisms into footwear represents a transformative solution for sustainable power generation. In this work, a piezoelectric generator (PEG), an electromagnetic generator (EMG), and a triboelectric generator (TEG) were hybridized within a single architecture to harvest biomechanical energy from walking, jogging, and running. The device incorporates pressure-sensitive Lead Zirconate Titanate (PZT) sheets, a spiral spring with dual neodymium (NdFeB) magnets with wound copper coils, and a nickel foam with polytetrafluoroethylene (PTFE) for triboelectricity operating in contact–separation mode. A dedicated energy-management circuit comprising independent rectification, DC bus energy aggregation, supercapacitor storage, and voltage regulation was implemented to efficiently utilize the harvested energy. The system was optimized through simulation using SOLIDWORKS 2023 and validated experimentally by using LabVIEW-NI myRIO FPGA system and treadmill. The proposed hybrid device achieved an exceptional peak output power of 58 mW and a voltage of 7.4 V, enough to charge low-power wearable devices, significantly surpassing the performance of most reported standalone and hybrid insole energy harvesters. These results demonstrate the effectiveness of multimodal integration in broadening operational bandwidth, increasing energy density, and enhancing compatibility with wearable applications. Piezoelectric, Electromagnetic and Triboelectric Insole Energy Harvesting (PET-IEH) establishes a new benchmark in biomechanical energy harvesting and paves the way for next-generation self-powered and sustainable wearable electronics. Full article

Magnesium alloys are attractive for temporary orthopaedic applications because of their biodegradability and favourable mechanical properties; however, their relatively rapid degradation under physiological conditions remains a challenge. In this study, the microstructural evolution, residual stress and electrochemical corrosion behaviour of WE43, a rare earth-containing magnesium alloy with yttrium, neodymium and zirconium as alloying elements, coated with titanium, were investigated as functions of deposition time using direct-current magnetron sputtering. Titanium coatings were deposited for 1, 1.5, 2 and 3 h, producing coating thicknesses of approximately 500, 650, 1000 and 1400 nm, respectively. Field-emission scanning electron microscopy, atomic force microscopy and grazing-incidence X-ray diffraction revealed progressive changes from fine-grained to dense and, subsequently, coarse-grained morphologies with increasing deposition time. The 2 h coating exhibited the largest crystallite size (27.17 ± 3.42 nm) and a moderate compressive residual stress of 605.3 ± 15.11 MPa. Potentiodynamic polarisation measurements showed that the 2 h coating produced the lowest corrosion current density (0.133 ± 0.026 mA/cm²) and calculated corrosion rate (2.93 ± 0.57 mm/year), representing a 67% reduction relative to independently measured, uncoated WE43 (8.87 ± 1.11 mm/year). The 3 h coating exhibited a higher compressive residual stress of 992.4 ± 21.7 MPa and a higher corrosion rate of 4.81 ± 0.74 mm/year, accompanied by localised microcracking after corrosion testing. Contact-angle measurements performed on the uncoated alloy and the 2 h coating showed an increase from 75.0 ± 2.1° to 83.0 ± 1.8°. Overall, the results indicated that corrosion performance was governed by the combined effects of coating morphology, crystallographic development and residual stress, with the 2 h deposition condition providing the most favourable balance under the present experimental conditions. Full article

The increasing use of electric vehicles has led to a growing demand for rare-earth elements, particularly neodymium (Nd), which is a critical component of Nd–Fe–B permanent magnets used in traction motors. End-of-life electric vehicle motors are therefore considered promising secondary resources for Nd recovery. In this study, a pyrometallurgical process using non-ferrous smelting slag as a flux was proposed for recovering Nd from Nd–Fe–B magnets contained in waste electric vehicle motors. Steel and magnet fractions obtained from a dismantled motor were melted at approximately 1600 °C under an air atmosphere, and Fe₂O₃ was added as an oxidizing agent to promote the selective oxidation of Nd. The oxidized Nd was subsequently partitioned into the slag phase as Nd₂O₃ through metal–slag separation. The effects of the slag flux addition ratio, Fe₂O₃ content, slag flux type, and crucible material on Nd recovery behavior were systematically investigated. Increasing the fayalite-based slag flux addition enhanced Nd transfer into the slag phase, and the highest Nd recovery of approximately 80% was obtained at a slag flux addition ratio of 30 wt%. The addition of 2 wt% Fe₂O₃ was found to be suitable for promoting stable Nd oxidation and efficient slag–metal separation. The non-ferrous smelting slag exhibited chemical and phase characteristics comparable to those of synthetic fayalite slag flux, resulting in similar Nd recovery performance. In addition, the crucible material significantly affected the process stability and Nd recovery behavior. Although a carbon crucible showed relatively high Nd recovery, severe slag foaming and crucible erosion occurred during melting. In contrast, alumina and MgO crucibles provided stable process conditions with comparable Nd recovery behavior, whereas zirconia crucibles caused relatively higher Nd loss. These results demonstrate that non-ferrous smelting slag can be effectively used as a flux for the pyrometallurgical recovery of Nd from end-of-life electric vehicle motors, offering a potential route for sustainable rare-earth recycling. Full article

Rare earth elements (REEs) are increasingly recognized as modulators of male reproductive health. This review presents the first comprehensive and critical analysis of the detrimental and potentially beneficial effects of REEs on male vertebrate reproductive function. In vivo and in vitro studies show that elements, particularly Gadolinium, Lanthanum, and Yttrium, share a toxicological profile characterized by oxidative stress, inflammation, mitochondrial dysfunction, endocrine disruption, and impairment of the blood–testis barrier. These mechanisms converge on both somatic and germ cell populations, ultimately compromising spermatogenesis and hormonal balance. Limited epidemiological data in humans are consistent with experimental findings, indicating inverse associations between seminal REE levels and sperm quality. CeO₂ nanoparticles represent an exception, showing dose-dependent duality: although some murine studies describe toxic effects, a broader and more consistent body of evidence indicates their protective action by restoring testicular homeostasis in diabetic models, in rats exposed to pesticides, pharmacological agents or irradiation, and in in vitro-treated spermatozoa. Preliminary data on Yttrium (YO) and Gadolinium (GdVO₄) nanoparticles similarly point to protective effects under pathological conditions, whereas Neodymium and Samarium show reproductive toxicity, including hormonal disruption and impaired sperm quality. Overall, REEs cannot be considered a homogeneous class: some pose reproductive hazards, others show potential biomedical utility. A systematic, mechanistic research framework is needed to resolve these dualities. It should contextualise reproductive risks in relation to the growing environmental and occupational exposure to REEs, while simultaneously exploring the biomedical potential of those elements that exhibit protective profiles. Full article

Rare earths are a strategically vital mineral resource on a global scale; the security of their supply chain and their recycling face severe challenges amid dual pressures of resource scarcity and environmental protection. This study focuses on the reverse supply chain for rare earth permanent magnet materials—specifically those based on praseodymium and neodymium—constructing a two-level game model comprising a rare earth oligopoly (Stackelberg leader) and two recyclers (Cournot followers). It systematically analyzes the dual decision-making behavior of recyclers between “recycling and selling” and “in-house remanufacturing”, and examines the impact of two policy instruments—government subsidies and environmental taxes—on the supply chain equilibrium. The study employs reverse induction to solve the game equilibrium and combines this with numerical simulation methods to compare the differing effects of the two policies on key indicators such as product output, market share, profit distribution, waste recovery volume, and recycling rates. The results indicate that there is strategic coordination and resource competition in recyclers’ decisions regarding recycling and remanufacturing, causing them to assume dual roles as both “suppliers” and “competitors” within the supply chain. Subsidy policies significantly incentivize recycling and remanufacturing activities, thereby increasing the recycling rate, but exert a slight squeeze on the profits of rare earth conglomerates. Environmental tax policies effectively curb primary mining and promote resource circulation, but may have a negative impact on the remanufacturing industry. Currently, value within the closed-loop rare earth supply chain is highly concentrated among upstream oligopolistic enterprises, whilst the recycling segment suffers from insufficient economic incentives and significant policy dependency. This study provides theoretical support and decision-making references for the government to optimize policy combinations and promote the high-quality development of the rare earth recycling industry. Full article

NdFeB waste is an important rare earth secondary resource, and the current industrial practice primarily employs a hydrochloric acid preferential dissolution method to recover rare earth elements (REEs). However, approximately 1% of REEs (e.g., cerium oxide, neodymium oxide, praseodymium oxide, and dysprosium oxide) remain in the leaching residue, resulting in low recovery efficiency. This work puts forward mechanochemical leaching (integrating mechanical activation and acid leaching) to replace traditional agitated leaching, which realizes synchronous mechanical activation and acid leaching within a stirred ball mill. A systematic comparison is conducted between these two leaching technologies, and the influences of operational variables on rare earth leaching efficiency are explored. The experimental results reveal that sustained mechanical grinding can pulverize particles down to the submicron level, induce substantial lattice distortion and amorphous transformation, destroy the physical coating of rare earth-bearing phases by iron oxides, and thereby drastically improve the extraction efficiency of REEs. The optimal conditions were determined as follows: stirring speed of 700 r/min, leaching temperature of 85 °C, HCl concentration of 1 mol/L, leaching time of 180 min and solid–liquid ratio of 100 g/L. Furthermore, this study reveals the synchronous evolution mechanism of particle refinement and phase transformation during mechanochemical leaching, providing an alternative and more economical recycling route for NdFeB waste. Full article

Techniques such as adsorption have been widely adopted to remove residual microplastics (MPs) because they are efficient at removing contaminants from aqueous environments. In this study, we report a novel, low-cost, biodegradable, and scalable biocomposite (LCMAG NaOH) derived from Luffa cylindrica fruit (LC) and micrometric natural magnetite (MAG), prepared without organic solvents, for the removal of MPs. The performance of LCMAG NaOH was evaluated for the removal of polystyrene (PS) and polyethylene terephthalate (PET) MPs, with particle sizes ranging from 75 to 600 µm in three distinct aqueous media: drinking water, simulated seawater, and water collected from the eutrophic lake of Dourados, MS, Brazil. The material was also evaluated for capture capacity and for reutilization in drinking water over three cycles, using a neodymium magnet. The biocomposite exhibited maximum removal capacities of 163 mg g⁻¹ and 158 mg g⁻¹ for PS and PET, respectively, in drinking water. Additionally, it demonstrated high magnetic recovery efficiency (>90% of the initial mass) and good reusability after immersion (10 and 20 min) and a dry step during the first cycle. Full article

Given the scarce data in the literature regarding the lanthanide content of Greek monofloral honey, Sc (Scandium), Y (Yttrium), La (Lanthanum), Ce (Cerium), Pr (Praseodymium), Nd (Neodymium), Sm (Samarium), Eu (Europium), Gd (Gadolinium), Tb (Terbium), Dy (Dysprosium), Ho (Holmium), Er (Erbium), Tm (Thulium), Yb (Ytterbium), Lu (Lutetium) and Th (Thorium) were determined in honeydew and nectar honey, using inductively coupled plasma mass spectrometry (ICP-MS). Results showed that, in general, honeydew honey had a higher lanthanide content than nectar honey, even though the determined values were below the limit of quantification. Preliminary reference values in this case for pine honey were Ce (26.82 ± 21.49 ng/L) and La (15.25 ± 11.82 ng/L). Adulteration testing was also performed using elemental analysis coupled to isotope ratio mass spectrometry (EA-IRMS), where no adulteration with cheap sugars was detected. Factor analysis identified the principal lanthanides related to honey botanical origin, basically Ce, and the k-NN algorithm classified the samples, achieving a training classification rate of 81.8% and a hold-out classification rate of 76.5%. Even in low amounts, lanthanides may contribute to the botanical origin identification of monofloral honey. Full article

Neodymium (Nd) and dysprosium (Dy) are two critical rare earth elements for fabricating NdFeB permanent magnets, which have crucial applications in modern technologies. The increasing global demand for Nd and Dy emphasizes new efficient processes for their recovery and purification, which are technologically challenging due to their close physical and chemical properties. Through systematic exploration, it was found that Lewatit VP OC 1026 resin impregnated with di-(2-ethylhexyl) phosphoric acid (D2EHPA) had a strong adsorption preference for Dy³⁺ over Nd³⁺, which is highly suitable for Dy-Nd separation from their mixed solutions under optimized conditions. The loaded resin could be eluted using dilute sulfuric solutions for recycling to the adsorption process. By employing a multistage adsorption-elution process analogous to distillation, efficient Dy-Nd separation and purification were realized from their mixed solution, with a prospective purity of 99.13% and recovery of 97.45% for Dy and a prospective purity over 99.96% and recovery of above 99.90% for Nd, despite the large concentration disparity between Dy and Nd, where Nd concentration is over 26 times that of Dy. This research demonstrates that efficient recovery and purification of metals from aqueous solutions can be achieved using selective resin adsorption processes analogous to distillation, despite large concentration differences of the metals in the solutions, which presents new alternative approaches. Full article

Green-synthesized Nd-doped (2%)-ZnO samples were produced using hydrothermal synthesis (HT) and freeze-drying (FT) procedures. A water extract from Vaccinium vitis-idaea leaves was used to modify the Nd-containing zinc acetate solution. The hydrothermal synthesis was carried out in an autoclave at 170 °C for 8 h. The lyophilization process was carried out for 20 h at 0.15 mbar and then for a further 4 h at 0.10 mbar and at a temperature of −100 °C. The final treatment after both these procedures was carried out at 400 °C for 2 h. Both synthesis methods produced mixtures of rugby-like and ridged ZnO particles. The FT particles possess smaller crystallites sizes (24 nm) and higher polarity (I002/I100) in comparison with the hydrothermally obtained particles. It was ascertained by EPR analyses that there was a higher concentration of oxygen-vacancies-related paramagnetic centers after freeze-drying synthesis (more intensive line at g = 2.000). The photocatalytic reaction rates of the freeze-dried samples toward Malachite Green dye discoloration were found to be higher than those of the HT samples. These rates were greatly affected by the smaller crystallites sizes, higher number of singly ionized oxygen vacancies in the crystal lattice and higher surface polarity. Full article

An improved method for separating magnetic minerals based on an isodynamic magnetic field is proposed in this work. The magnetic field distribution generated by the system was first analyzed through numerical simulations performed with finite element electromagnetic simulation software, and the simulation accuracy was subsequently validated against experimental data. Through system modeling and parameter sensitivity analysis, the regulatory mechanisms of various parameters of the field properties were thoroughly investigated. Numerical results show that a constant magnetic force field forms in the separation zone at a 25° arc center angle of the curved pole head, while poor field uniformity occurs at 20° or 30°. A stable constant magnetic force field can be generated in the separation zone when the large arc radius of the curved pole head is 300 mm, 600 mm or 1200 mm, or when permanent magnet materials including N30–N45-grade neodymium iron boron (NdFeB) and ferrite are adopted. The large arc radius of the curved pole head, as well as the type and grade of the permanent magnet, only affect the magnitude of the magnetic force in the separation zone, with no significant correlation with the uniformity of the constant magnetic force field. A constant magnetic force field is generated when the thickness of the side patch magnet on the curved pole head is 40–70 mm and the magnetic system working air gap is 50–60 mm; the magnetic force field will lose uniformity once the parameters deviate from the above ranges. Full article