The researchers used commercially available rod-shaped cerium dioxide particles, designated CeO2 NRs, with most of the measured size distribution between 6.5 and 11.7 nanometres. Cerium dioxide has redox properties associated with the reversible conversion of Ce3+ and Ce4+, allowing it to participate in reactions involving reactive oxygen species. This dualistic behavior has supported interest in possible antioxidant biomedical uses while also making biological effects dependent on factors such as concentration, exposure duration, morphology and route of administration. Earlier studies have reported both antioxidant activity and harmful effects involving oxidative stress, inflammation and cellular damage. The current experiments were designed to examine neurological function and signaling rather than to establish the material’s general safety or toxicity.

Eight-week-old male C57BL/6J mice received 10.5 milligrams per kilogram of CeO2 NRs by intranasal instillation once daily for three consecutive days. Control animals received the same volume of saline. After the last exposure, the researchers conducted behavioral tests, seizure-susceptibility tests and EEG recordings before collecting brain tissue for histological staining, transcriptome sequencing and proteomics. A separate experiment included controls, particle-exposed mice, mice given anpirtoline alone and exposed mice treated with anpirtoline. The agonist was administered intraperitoneally at 0.5 milligrams per kilogram, 30 minutes after each particle exposure. The selected particle dose was lower than the 40 milligrams per kilogram used in some earlier mouse studies that focused heavily on oxidative brain injury and cell death.

Analysis of brain tissue by inductively coupled plasma optical emission spectrometry showed significantly greater cerium accumulation in the hippocampus and striatum than in the other examined regions, with reported differences of p less than 0.0001. Biological transmission electron microscopy then revealed rod-shaped or particulate cerium dioxide structures inside hippocampal neurons, including material enclosed in lysosomes and particles observed in nuclei. In a separate lysosome-mimicking experiment, artificial lysosomal fluid altered the particles’ surface structure, reduced their crystallinity and broadened selected diffraction peaks, consistent with partial transformation under lysosome-like conditions. Primary cortical neurons took up the particles after one hour of exposure to fluorescently labeled CeO2 NRs at 100 micrograms per millilitre. After three days, 100 micrograms per millilitre reduced measured apoptosis, whereas 500 and 1,000 micrograms per millilitre significantly increased apoptosis and neuronal death. The tested concentrations exceeded those directly measured in vivo, however, and the authors cautioned that the cellular results could not be directly extrapolated to physiological exposure.

Behavioral testing showed a consistent shift toward unusually intensive exploration. In the open-field test, exposed mice spent more time in the central zone and entered it more frequently than controls. In the novel-object recognition test, they spent longer and made more frequent approaches toward the novel object. Particle-exposed animals also spent a greater proportion of their time in the open arms of the elevated plus maze, a pattern the authors associated with increased risk-taking. Their forced-swim immobility was approximately 20%, compared with roughly 60% in controls, while social-preference and social-novelty indices were also elevated. The investigators interpreted the combined pattern as increased novelty seeking and weaker behavioral inhibition. These assays measured behavioral differences in mice and did not diagnose a human psychiatric disorder or establish the motivation underlying the altered behavior.

Seizure testing indicated that the particles also changed responses to an epileptogenic challenge. Under cumulative pentylenetetrazol administration, exposed mice developed more severe seizure-like responses after the first and second injections than controls, although the groups no longer differed significantly after the third and fourth injections. EEG recordings provided a separate measure of network excitability. Mice exposed to CeO2 NRs displayed burst-like discharges, occasional epileptiform spikes and localized increases in time-frequency power despite not exhibiting overt seizures. When a larger pentylenetetrazol challenge was administered, particle-exposed animals produced more frequent and prolonged epileptiform activity than animals receiving pentylenetetrazol alone. The measured outcomes therefore associate intranasal particle exposure with increased abnormal electrical activity and reduced resistance to seizure-inducing stimulation, while the absence of spontaneous overt seizures in the exposed mice remains an important boundary on the findings.

Integrated transcriptomic and quantitative proteomic analyses pointed toward changes in neurotransmitter regulation, oxidative metabolism, inflammation and neuronal stability. Under the study’s differential-expression criteria, 33 genes were upregulated and 39 were downregulated in exposed mice compared with controls. Htr1b, the gene encoding the 5-HT1B receptor, was among the reduced transcripts, while expression of Glul, which encodes glutamine synthetase, also fell. Pathway analysis implicated oxidative phosphorylation, arachidonic-acid-related inflammatory pathways, chemokine signaling and mitogen-activated protein kinase signaling. Quantitative proteomics identified 6,733 proteins across 20 samples, including decreases in Kcnt2 and Slc24a3, which are involved in maintaining neuronal electrical stability. RNA and protein integration revealed several concordant changes associated with oxidative stress, but the effects were modest and may have been weakened by inter-individual variability because the transcriptomic and proteomic measurements did not use matched animals.

Immunofluorescence measurements in the hippocampus and striatum showed increased serotonin fluorescence together with reduced 5-HT1B receptor expression. The abundance of tryptophan hydroxylase 2, described in the study as a rate-limiting enzyme of central serotonin synthesis, did not change significantly. The researchers therefore inferred that the higher local serotonin signal was more consistent with altered utilization, secretion or feedback regulation than with increased synthesis. The 5-HT1B receptor acts as an inhibitory presynaptic autoreceptor and heteroreceptor that restrains the release of serotonin and other neurotransmitters. Its downregulation was accompanied by increased hippocampal c-Fos, used as a marker of neuronal activation, and elevated intracellular calcium in exposed primary neurons. Stronger inducible nitric oxide synthase and weaker arginase-1 signals indicated a shift toward a more pro-inflammatory and less repair-oriented cellular environment. BV2 microglial cells exposed to CeO2 NRs also showed increased inducible nitric oxide synthase expression, supporting a direct effect on the cell model under the tested conditions.

The anpirtoline experiment provided functional evidence that impaired 5-HT1B signaling contributed to at least some of the measured abnormalities. The agonist reduced central-zone activity to control levels in the open-field test, shortened novel-object exploration, reduced open-arm time and brought social-preference measures closer to control values. It partially restored forced-swim immobility. During the cumulative seizure challenge, treated exposed mice had lower early Racine seizure scores than exposed animals without anpirtoline and resembled controls after the first injection. Anpirtoline also reduced abnormal EEG discharges and high-power regions during the pentylenetetrazol challenge, while it did not significantly alter baseline EEG activity in unexposed mice. Molecular analyses showed partial restoration of 5-HT1B receptor protein, lower serotonin and c-Fos signals, and increased arginase-1 expression in the hippocampus and striatum. These results support a functional role for the receptor, but the intervention was partial and does not exclude contributions from inflammation, oxidative stress, glutamate signaling and gamma-aminobutyric acid release.

Overall, the experiments connect short-term intranasal CeO2 NR exposure with brain accumulation, altered exploration, increased seizure susceptibility, abnormal EEG activity, serotonergic dysregulation, neuroinflammation and neuronal hyperactivation in male mice. The rescue experiments indicate that loss of 5-HT1B signaling is an important mechanism rather than the only possible mechanism. Important limitations remain: the work involved short exposure in one mouse strain and sex, the in vitro concentrations exceeded directly measured in vivo levels, and species differences in nasal anatomy and olfactory deposition prevent direct translation of the dose into a human exposure. The anpirtoline findings therefore provide a mechanistic lead for nanomaterial safety research and future testing, not evidence of a clinical treatment or a quantified human neurological hazard.

Subject of Research: Neurobehavioral effects of intranasally administered cerium dioxide nanorods in male mice

Article Title: High-dose cerium dioxide nanorods induce behavioral and electroencephalographic abnormalities through 5-HT1B receptor signaling disruption with an evaluation of anpirtoline's therapeutic potential

Article References: Liu, M., Li, Y., Shen, C., Huang, H., Liu, Q., Fu, B., Wu, B., Wu, X., Luo, Y., Shan, Y., Niu, X., & Zhao, G. (2026). High-dose cerium dioxide nanorods induce behavioral and electroencephalographic abnormalities through 5-HT1B receptor signaling disruption with an evaluation of anpirtoline's therapeutic potential. Materials Today Bio, 41, Article 103749. https://doi.org/10.1016/j.mtbio.2026.103749

Image Credits: AI Generated

DOI: 10.1016/j.mtbio.2026.103749

Keywords: cerium dioxide nanorods, intranasal exposure, mouse neurotoxicity, serotonin 1B receptor, anpirtoline, electroencephalography, seizure susceptibility, neuroinflammation, brain accumulation, multi-omics, High-dose, cerium

Combining five or more metals into a single-phase solid solution offers a way around that limitation. The high-entropy effect, already demonstrated for high-entropy alloys and oxides, can deliver catalytic behavior far better than any individual component. High-entropy carbides, however, are still in their infancy. Multiple metallic elements are chemically immiscible within a carbide lattice, and producing nanosized carbides with controlled size and morphology is difficult. The synthesis routes developed so far, including electrical-discharge-induced bulk-to-nanoparticle transformation, ultra-fast Joule heating, nanoconfined impulse synthesis on carbon nanotube films, pyrolysis of metal-ion-impregnated zeolitic-imidazolate-framework-derived carbon, and solid-phase combustion synthesis, have all expanded the compositional space. Every material reported to date, though, has been a dense, solid particle.

That constraint represents a missed opportunity. Hollow nanostructures offer high surface-to-volume ratios and abundant interior voids, which translate into more exposed active sites, lower mass-transport resistance, and shorter charge-transport pathways. Conventional hollow synthesis, however, relies on templates, which means multi-step preparation and often harsh template-removal conditions. In parallel, rare-earth elements are known to tune the electronic structure of transition-metal alloys and oxides and to boost catalytic activity, but rare-earth-containing high-entropy carbide catalysts remain scarce, largely because the large atomic-size mismatch between rare earths and transition metals hinders incorporation of rare-earth atoms into the carbide lattice. Fabricating hollow structures and introducing rare earths into high-entropy carbides are thus two formidable challenges that conventional synthesis has struggled to meet simultaneously.

Molten-salt electrolysis offers a mild, low-temperature alternative that converts inexpensive oxide precursors directly into nanomaterials in a single step. Sure and Schwandt first produced single-phase (NbTaTiZrHf)C nanoparticles of 15 to 80 nanometers by electro-deoxidation of a metal oxide and graphite mixture in molten calcium chloride at 900 degrees Celsius. Yang and colleagues later coupled anodic carbon dioxide capture with in situ cathodic carburization in the MSCC-ET process, preparing (NbTaTiZrHf)C of 20 to 100 nanometers in a lithium chloride-calcium chloride-potassium chloride melt at 980 degrees Celsius with carbon dioxide as the sole carbon source, and reported an alkaline hydrogen evolution overpotential of 350 millivolts at 10 milliamperes per square centimeter with a Tafel slope of 61 millivolts per decade. Both studies, however, were confined to five-component d-block carbides with solid particulate morphologies.

Now a team led by Wen Ma at the Inner Mongolia Key Laboratory of New Materials and Surface Engineering, Inner Mongolia University of Technology, has broken both barriers at once. The researchers achieved the first synthesis of hollow nanostructured high-entropy carbides with compositions (HfNbTaTiZr)C, (HfNbTaTiZrRE)C where the rare earth is gadolinium, cerium, or yttrium, and (HfNbTaTiZrCeY)C, through a direct electroreduction process in molten calcium chloride-sodium chloride at 800 degrees Celsius. All of the as-synthesized carbides exhibit a single face-centered cubic phase and compositional homogeneity from the nanoscale to the microscale. Critically, the team found that the microstructure can be tailored from solid to hollow particles simply by selecting a different carbon source, dispensing with templates altogether.

When evaluated as hydrogen evolution catalysts in 1.0 molar potassium hydroxide, the engineered hollow architecture combined with rare-earth incorporation substantially enhanced performance, and the dual-rare-earth compositions outperformed their single-rare-earth analogues. The best performer, (HfNbTaTiZrCeY)C, reached an overpotential of just 167 millivolts at 10 milliamperes per square centimeter, with a Tafel slope of 58.8 millivolts per decade and a charge-transfer resistance of only 2.7 ohms. Those figures compare favorably with the 350-millivolt overpotential and 61-millivolt-per-decade Tafel slope reported for the earlier solid five-component carbide, and they were achieved without a trace of noble metal.

The work was published in the Journal of Advanced Ceramics on September 10, 2026. In the paper, the authors describe how a family of hollow rare-earth-containing high-entropy carbide nanoparticles was successfully synthesized for the first time, exhibiting a single face-centered cubic structure obtained by a one-pot electroreduction process from oxides and carbon black in molten chlorides at 800 degrees Celsius. The results show that the microstructure of these carbides can be easily tailored from solid to hollow particles by selecting different carbon sources, and that the electrocatalytic performance for hydrogen evolution is noticeably enhanced by the tailored hollow nanostructure compared with solid counterparts.

The dual rare-earth incorporation appears to do more than add sites. According to the researchers, adding two distinct rare-earth species, cerium and yttrium, into the transition-metal-based carbides can not only construct more electroactive sites but also accelerate electrocatalytic kinetics, yielding enhanced hydrogen evolution performance that far surpasses the single-rare-earth counterparts. The superior activity arises from the synergistic effects of the two rare-earth elements working together within the carbide lattice, a combination that the large atomic-size mismatch had long made difficult to realize.

The study establishes a general and facile platform for synthesizing a wide family of hollow rare-earth-containing high-entropy carbide nanoparticles and suggests a new design strategy for high-performance noble-metal-free catalysts. The authors note that further work is needed to clarify how individual rare-earth elements govern the electronic structure and activity, a question that will determine how far this design principle can be pushed. Other contributors include Hongxia Liu, Jinqiao Zhang, Shiyu Qin, and Yu Bai from the School of Materials Science and Engineering at Inner Mongolia University of Technology in Hohhot, China. The work was supported by the Carbon Peak and Carbon Neutrality Research Program of Higher Education Institutions in Inner Mongolia Autonomous Region, the Natural Science Foundation of Inner Mongolia Autonomous Region, the National Natural Science Foundation of China, and Science and Technology Projects of Inner Mongolia Autonomous Region.

For the hydrogen economy, the implications are straightforward. A catalyst that combines abundant hafnium, niobium, tantalum, titanium, and zirconium with modest amounts of cerium and yttrium, synthesized in a single electrochemical step at 800 degrees Celsius, delivered performance approaching that of far more complex engineered systems while avoiding both noble metals and template chemistry. If the molten-salt electroreduction route proves scalable, the combination of hollow architecture and dual rare-earth tuning could become a standard design principle for the next generation of earth-abundant water-splitting catalysts, bringing low-cost green hydrogen a meaningful step closer to reality.

Subject of Research: First hollow rare-earth-containing high-entropy carbide nanoparticles synthesized by molten-salt electroreduction as noble-metal-free hydrogen evolution catalysts

Article Title: First hollow rare-earth-containing high-entropy carbide nanoparticles: A facile electrochemical route yields efficient noble-metal-free hydrogen evolution catalyst

Article References: First hollow rare-earth-containing high-entropy carbide nanoparticles: A facile electrochemical route yields efficient noble-metal-free hydrogen evolution catalyst. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: high-entropy carbides, hydrogen evolution reaction, rare-earth elements, molten-salt electrolysis, electrocatalysis, hollow nanoparticles, noble-metal-free catalysts, water splitting, transition metal carbides, green hydrogen, cerium, yttrium

Rare earth elements are a group of seventeen chemically similar metals, including neodymium, cerium, and ytterbium, that have become indispensable to modern technology. They appear in magnets, batteries, catalysts, and electronic displays, and as mining and manufacturing have intensified worldwide, these elements have quietly accumulated in soil, water, and air. People are exposed through food, drinking water, and dust, and pregnant women pass them across the placenta to their developing babies. While previous research had hinted that prenatal exposure to these metals could impair childhood neurodevelopment, the biological mechanisms remained murky.

To probe those mechanisms, researchers turned to the Wuhan Healthy Baby Cohort, a long-running birth cohort study in central China. The team, led by Ya Xie and Wei Xia of Wuhan Children’s Hospital and Huazhong University of Science and Technology, measured concentrations of thirteen rare earth elements in urine samples collected from mothers during the first trimester of pregnancy. They then performed metabolomic profiling on cord blood, the blood remaining in the placenta after birth, capturing a snapshot of each newborn’s metabolic state. Two years later, trained assessors evaluated each child’s cognitive and motor skills using the Bayley Scales of Infant Development, a widely used standardized test.

The results were striking. After adjusting for a range of covariates, the researchers found that higher first-trimester maternal levels of seven rare earth elements were each significantly associated with increased odds of cognitive developmental delay. The elements neodymium, samarium, gadolinium, holmium, erbium, thulium, and ytterbium each carried elevated risk, with adjusted odds ratios ranging from 1.13 to 1.25 for every one-unit increase in natural log-transformed urinary concentration. In practical terms, a modest rise in maternal exposure translated into a measurable increase in the likelihood that a toddler would score below developmental benchmarks on cognitive testing.

Because people are exposed to mixtures of rare earth elements rather than single metals in isolation, the team also used two statistical approaches designed for environmental mixtures: quantile g-computation and weighted quantile sum regression. Both methods confirmed a positive overall mixture effect, meaning the combined burden of rare earth elements raised the risk of both cognitive and psychomotor developmental delays. Intriguingly, the two methods identified different dominant contributors. Ytterbium emerged as the primary driver of cognitive developmental delay, while cerium played the leading role in psychomotor delay, hinting that individual rare earth elements may exert distinct biological effects even within a chemically similar family.

The study’s most innovative move came next. Rather than treating metabolites as isolated signals, the researchers applied weighted gene co-expression network analysis, a technique originally developed for genomics, to the cord blood metabolomic data. Using a soft-thresholding power of 5, which produced a network with strong scale-free topology, the team clustered thousands of metabolites into thirteen color-coded modules representing coordinated metabolic networks. This approach allowed them to ask which entire biological pathways, rather than individual molecules, were perturbed by prenatal rare earth exposure.

Two modules stood out. Prenatal rare earth element exposure was consistently associated with perturbations in metabolic modules enriched in lysophospholipids and phosphatidylethanolamines, two classes of phospholipids that are fundamental building blocks of cell membranes. These molecules are especially important in the developing brain, where membranes are being rapidly assembled and remodeled as neurons grow and form connections. The finding suggests that rare earth elements may interfere with fetal neurodevelopment by scrambling the lipid architecture on which brain construction depends.

Crucially, the association was more than correlational. Mediation analyses demonstrated that the lysophospholipid and phosphatidylethanolamine modules partially mediated the link between prenatal exposure and increased risk of neurodevelopmental delay. In other words, part of the statistical pathway from rare earth exposure to developmental impairment runs through these disrupted lipid networks. The identification of a plausible biological mechanism elevates the findings from an observational association toward a more causal interpretation, though the researchers note that mediation captures only a portion of the overall effect and other pathways likely remain to be discovered.

The implications ripple outward in several directions. For public health officials, the study strengthens the case for including rare earth elements in routine risk assessments during pregnancy, a step that has lagged far behind their growing environmental presence. As global demand for these metals surges with the green energy transition and the proliferation of electronic devices, exposure levels in ordinary populations may continue to climb. The study also points toward potential interventions: if phospholipid disruption is a key mechanism, researchers could eventually explore whether nutritional or pharmacological strategies that support healthy lipid metabolism during pregnancy might buffer developing brains against environmental insult.

For the families in Wuhan whose participation made the study possible, the research offers no easy answers, since rare earth exposure is diffuse and difficult for individuals to avoid. But it adds an urgent data point to a larger conversation about the hidden costs of the technologies that define modern life. The metals that power our digital world are now demonstrably reaching the next generation before they take their first breath, and the developing brain appears to register their presence in ways we are only beginning to measure. As the authors conclude, the findings highlight the need for health risk assessment of rare earth element exposure during pregnancy, and they provide early clues to intervention targets that could protect children before the damage is done.

Subject of Research: Prenatal rare earth element exposure and its association with neurodevelopmental delay and phospholipid metabolic disruption in children

Article Title: Cord blood metabolic network profiles link prenatal rare earth element exposure to neurodevelopmental delay in 2-year-old children

Article References: Xie, Y., Qiu, L., Fang, X., Cao, Z., Li, S., Gong, H., Tan, T., Wang, J., Li, Y., Xu, S., Xiao, H., Zhou, A., & Xia, W. (2026). Cord blood metabolic network profiles link prenatal rare earth element exposure to neurodevelopmental delay in 2-year-old children. BMC Medicine. https://doi.org/10.1186/s12916-026-05306-9

Image Credits: AI Generated

DOI: 10.1186/s12916-026-05306-9

Keywords: rare earth elements, prenatal exposure, neurodevelopmental delay, metabolomics, cord blood, phospholipid metabolism, WGCNA, Bayley Scales, birth cohort, cognitive development, psychomotor development, environmental health

The stakes are high. Rare earth elements underpin LEDs, wind turbines, electric vehicle motors, mobile phones and defense technologies, and analysts expect demand to outstrip current supply in the coming years. Mining new rare earths is difficult, geographically concentrated and environmentally fraught, so recycling end-of-life products has become a central strategy in the push toward a circular economy. Waste fluorescent lamps are an especially attractive feedstock because their phosphor powder contains roughly six weight percent rare earths — a far richer grade than many natural ores, where individual rare earth concentrations can be orders of magnitude lower. The catch is that the powder also carries a heavy load of unwanted calcium and other impurities that complicate downstream separation.

The research team, led by Pallabi Roy and Musthaq Mohammad Syed under the supervision of Arunabh Meshram and Krishanu Biswas, attacked that problem with an integrated enrichment-and-adsorption strategy. Their first move was thermal rather than chemical: a three-cycle alkali roasting process at 800 degrees Celsius. This treatment transforms the stubborn phosphate phases in the phosphor powder — crystalline compounds that resist ordinary dissolution — into far more reactive oxides. It is a decisive preprocessing step, because the chemistry of the rare earth phosphates used in lamp coatings makes them notoriously reluctant to give up their metal atoms under mild leaching conditions. Converting them to oxides opens the door to hydrometallurgical recovery with weaker, cheaper reagents.

Once roasted, the powder went through a sequential two-stage leaching protocol designed to dissolve the useful elements while stripping away calcium, the main contaminant. The first stage used 2 moles per liter sulfuric acid at 40 degrees Celsius to attack the oxide matrix. The second stage was more unusual: a brine leach using 2.5 moles per liter sodium chloride solution held at pH 5, 90 degrees Celsius, for 90 minutes. The high chloride concentration leverages salt solubility chemistry to pull calcium out of the solid, while the near-neutral pH avoids dissolving more of the rare earth fraction than necessary. The combined effect was dramatic: calcium content dropped from 36.74 to 8.06 weight percent, a 78.1 percent decrease, leaving behind a solid substantially enriched in the target rare earths.

With the pre-concentrated material in hand, the team turned to the adsorption stage, which is where the study’s most distinctive chemistry lives. Chitosan is a polysaccharide obtained by deacetylating chitin, the structural polymer of crustacean shells, and it is prized in materials science for its abundance, biodegradability and dense array of amine groups that naturally bind metal ions. On its own, however, chitosan’s affinity for rare earths is limited. The researchers therefore grafted EDTA — ethylenediaminetetraacetic acid, the workhorse chelating agent of analytical chemistry — onto the chitosan backbone. EDTA’s carboxylate and amine groups wrap around metal ions in stable coordination complexes, and when anchored to a solid polymer, they act as molecular fishing lines that pluck dissolved rare earth cations out of solution.

The adsorption experiments were run under optimized conditions of pH 5, 50 degrees Celsius and 24 hours of contact time. The performance varied across the five elements, and the pattern is chemically telling. Terbium, the heaviest and most valuable of the set, was captured most efficiently at 82.4 percent, followed by yttrium at 79.15 percent, cerium at 74.10 percent, lanthanum at 60.13 percent and europium at 31.87 percent. Adsorption efficiency generally tracks ionic radius and hydration chemistry: smaller, more highly charged rare earth cations form stronger complexes with EDTA ligands, so the heavy elements win out. Europium’s comparatively modest uptake reflects the specific speciation and competition among ions in the leach liquor rather than a failure of the material itself.

To quantify the adsorbent’s true capacity, the team fitted their equilibrium data to the Langmuir isotherm, a classical adsorption model that assumes a finite number of identical binding sites forming a single molecular layer on the surface. The fitted maximum capacities were 179.54 milligrams of terbium per gram of adsorbent, 115.35 milligrams for cerium, 106.45 for yttrium, 77.68 for lanthanum and 28.47 for europium. Good Langmuir fits indicate monolayer adsorption and site saturation — in other words, the EDTA groups behave in a predictable, well-behaved manner rather than showing the erratic multi-layer accumulation that plagues many crude sorbents. For a bio-derived material, capacities approaching 180 milligrams per gram for terbium are competitively strong against synthetic ion-exchange resins.

The choice of a biopolymer adsorbent is more than an aesthetic nod to green chemistry. Conventional rare earth separation relies on solvent extraction circuits that consume large volumes of organic solvents and generate acidic wastewater, and on ion-exchange resins derived from petrochemical feedstocks. Chitosan-based sorbents are renewable, biodegradable and inexpensive, and earlier work by other groups — including EDTA- and DTPA-functionalized chitosan for chromatographic rare earth separation, and magnetic chitosan composites for heavy metal capture — has established the platform’s versatility. The IIT Kanpur team’s own previous study demonstrated the same functionalized chitosan recovering neodymium and dysprosium from discarded hard disk magnets, and the present work extends the concept to a fundamentally different waste stream with a messier, calcium-laden chemistry.

What makes the study notable is less any single step than the integration. Alkali roasting, selective sequential leaching and bio-based adsorption are each known techniques, but combining them into one coherent flowsheet that takes raw lamp phosphor powder from six percent rare earths to a pre-concentrated, selectively adsorbed product is the kind of process-level engineering that determines whether lab chemistry can ever scale. The authors frame the approach as a technically efficient route for selective rare earth recovery that contributes to sustainable and circular economic development, and the framing is fair: the strategy replaces aggressive, solvent-intensive separation with a sequence that leans on heat, table salt, dilute acid and a shrimp-shell polymer.

Challenges remain before such a process could feed industrial supply chains. Adsorption selectivity among the five elements is incomplete — europium lags considerably — so a full recovery scheme would still need downstream polishing or fractional desorption to deliver separated, high-purity oxides. Adsorbent regeneration and reuse over many cycles, process economics at tonne scale, and the logistics of collecting spent lamps all remain open questions that the published data do not fully resolve. Yet as a demonstration, the work lands at a consequential moment. The fluorescent lamp is a fading technology being replaced by LEDs worldwide, which means the stock of phosphor-rich waste is peaking right now and will gradually become the legacy inventory of a bygone lighting era. Harvesting its rare earths before they disperse irretrievably is exactly the kind of urban mining that resource security strategists have been calling for, and this study shows a credible, greener path for doing it — one grounded not in exotic chemistry but in sulfuric acid, brine and the shells of the seafood industry.

Subject of Research: Recovery of rare earth elements from waste fluorescent lamp phosphor powder using integrated leaching and bio-based adsorption

Article Title: Recovery of rare earth elements (Y, La, Ce, Eu and Tb) from waste fluorescent lamps via integrated leaching and EDTA-functionalized Chitosan adsorption

Article References: Roy, P., Syed, M. M., Meshram, A., & Biswas, K. (2026). Recovery of rare earth elements (Y, La, Ce, Eu and Tb) from waste fluorescent lamps via integrated leaching and EDTA-functionalized Chitosan adsorption. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38276-9

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38276-9

Keywords: rare earth elements, fluorescent lamps, yttrium, terbium, europium, lanthanum, cerium, EDTA-functionalized chitosan, adsorption, leaching, urban mining, circular economy

Bainbridgeite-(NdCe) has the ideal chemical formula Na2Ba2NdCe(CO3)6·3H2O, meaning that each unit of the mineral combines two sodium atoms, two barium atoms, one neodymium atom, one cerium atom, six carbonate groups, and three water molecules. It belongs to the mckelveyite group, a family of rare hydrated carbonates whose general formula can be written as A3B3(CO3)6·3H2O, where the A sites are occupied by elements such as sodium, calcium, yttrium, zirconium, and neodymium, while the B sites host strontium, barium, cerium, and lanthanum. The new species is the neodymium analogue of bainbridgeite-(YCe), which was described from the same locality in 2024, and it is also the barium-neodymium analogue of alicewilsonite-(YCe). Both the mineral and its name were approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association under proposal number IMA 2023-018, and the holotype specimen has been deposited in the collection of the Canadian Museum of Nature in Ottawa under catalogue number CMNMC 90534.

The mineral was found at the Poudrette quarry, a site within the Mont Saint-Hilaire alkaline and agpaitic complex that has produced an extraordinary number of new mineral species over the decades. Bainbridgeite-(NdCe) turned up in two quite different geological settings. The first is an environment referred to in the literature as carbonate pegmatites or carbonate vugs, bodies rich in calcite that lack the pyroxene and amphibole minerals typical of alkaline pegmatites and whose origin remains poorly understood. In this setting, the type material was recovered from a heavily altered body consisting mostly of calcite and albite, collected by Elsa Pfenninger-Horváth and László Horváth in February 1978. There, bainbridgeite-(NdCe) forms thin rims, up to twenty to thirty micrometers thick, on barrel-shaped short prismatic crystals reaching two millimeters in size. Remarkably, the cores of those same crystals are composed of bainbridgeite-(YCe), with an intermediate zone corresponding to a member of the bainbridgeite-(YCe)-alicewilsonite-(YCe) series, so a single crystal records a sequence of changing chemical conditions during its growth.

The second occurrence is quite different. In a hornfels rock, bainbridgeite-(NdCe) appears as white or pale-grey tabular, saucer-shaped crystals up to half a millimeter across, commonly stacked together and associated with yellow acicular rutile, colourless hexagonal tabular gmelinite-Na, sphalerite, calcite, analcime, and pyrite. In these crystals, the entire grain is bainbridgeite-(NdCe), with no yttrium-dominant core. The coexistence of the mineral in both a carbonate-rich vug environment and a hornfels highlights the versatility of late-stage fluids in the Mont Saint-Hilaire complex, which apparently could deliver the right combination of sodium, barium, carbonate, and rare-earth elements in more than one geological context.

Physically, bainbridgeite-(NdCe) is a pale yellow, pale orange, white, or pale grey mineral with a white streak and a vitreous lustre. It shows no cleavage, has an uneven fracture, and a Mohs hardness of three, determined on material from the hornfels occurrence because the rims in the holotype are too thin for such a test. The mineral is non-fluorescent under ultraviolet light, and its calculated density is 3.49 grams per cubic centimeter. Optically it is biaxial positive, with refractive indices of 1.577, 1.592, and 1.657 for the three principal axes, and a measured axial angle of forty degrees. These modest, unassuming properties are typical of the mckelveyite group, whose members are usually recognized not by striking appearance but by careful chemical and crystallographic analysis.

Characterizing the new species demanded a battery of analytical techniques, and the researchers had to contend with some serious practical obstacles. Electron microprobe analyses were performed with a JEOL 8230 SuperProbe using wavelength-dispersive spectroscopy, but bainbridgeite-(NdCe) is unstable under the electron beam, so larger beam diameters of ten to twenty micrometers were used to minimize element migration, and time-dependent intensity corrections were applied for several elements. Water and carbon dioxide contents could not be measured directly because of the scarcity of material and were instead calculated from stoichiometry. Infrared spectroscopy, carried out at the Canadian Conservation Institute on a tiny fragment mounted in a diamond anvil cell, confirmed the presence of water molecules through characteristic oxygen-hydrogen stretching and hydrogen-oxygen-hydrogen bending bands, and revealed a band at 1064 wavenumbers indicating that the carbonate groups in the structure are polarized rather than symmetric.

X-ray diffraction work proved equally challenging. Powder diffraction data could not be collected from pure bainbridgeite-(NdCe), because not enough separate grains could be recovered, so the measured pattern represents an average of the new mineral and its yttrium-dominant neighbour. Single-crystal diffraction, performed at the Natural History Museum in Oslo on a Rigaku XtaLAB Synergy-S diffractometer, faced the same problem: because bainbridgeite-(NdCe) occurs only as a thin rim on bainbridgeite-(YCe) and the boundary between the two phases is not visually identifiable, the structural model represents an average of both phases. Even so, the structure was solved and refined to an R1 value of 0.036 in the triclinic space group P1, with unit-cell parameters a of 9.0525 angstroms, b of 9.1178 angstroms, c of 6.8518 angstroms, and a cell volume of 438.23 cubic angstroms. The structure is of the weloganite type and is strongly pseudotrigonal, with six independent large-cation sites forming two alternating layers parallel to the ab plane, three water molecules bonded to barium- and sodium-centred polyhedra, and six carbonate groups, three of which lie nearly coplanar with the (001) plane.

The heart of the discovery lies in the distribution of cations among those sites. By combining electron microprobe data, refined site-scattering factors from the diffraction experiment, interatomic distances, bond valence calculations, and charge balance, the team demonstrated that neodymium atoms overwhelmingly prefer the site designated Nd6, while cerium atoms concentrate at the Ce3 site. The evidence is compelling from chemistry alone: the neodymium content of the holotype, 0.35 atoms per formula unit, is significantly higher than that of any single heavier lanthanide, higher than the combined total of all heavier lanthanides from samarium through dysprosium, higher than the yttrium content, and far higher than the neodymium content of the yttrium-dominant holotype of bainbridgeite-(YCe). A specimen from the hornfels shows an even stronger pattern, with 0.41 atoms of neodymium per formula unit. Structural evidence reinforces the case: the site occupied predominantly by yttrium in bainbridgeite-(YCe) is instead dominated by neodymium and other lanthanides in the new mineral, consistent with a substitution of yttrium by rare-earth elements at that position.

Why does neodymium, an element that usually disperses among other rare-earth-bearing minerals rather than forming its own phases, concentrate here? The authors propose a mechanism rooted in crystal chemistry. Neodymium has a particular affinity for yttrium, and in late-stage agpaitic environments, as yttrium becomes depleted from the residual fluid, neodymium can rise to become the dominant rare-earth element in a newly forming phase. The team previously demonstrated this behaviour in piilonenite-(Nd), another neodymium-dominant carbonate from Mont Saint-Hilaire. The model makes a testable prediction: samarium and gadolinium, which are smaller than neodymium but larger than the heavy rare earths that typically follow yttrium, should show an even greater affinity for yttrium-favouring sites and should therefore also become enriched in late-stage phases. The chemical data bear this out. Samarium and gadolinium contents rise from negligible values of 0.01 and 0.03 atoms per formula unit in the yttrium-dominant cores of the crystals to 0.18 and 0.14 atoms per formula unit in the neodymium-dominant rims, with similar enrichment in the hornfels material.

Bainbridgeite-(NdCe) thus does more than add a name to the mineralogical record. It provides a natural experiment in element sorting, showing how the subtle size preferences of individual rare-earth atoms can drive their separation into distinct structural sites as a magmatic system evolves. Because rare-earth elements underpin modern technologies from permanent magnets to phosphors, understanding the crystallochemical rules that govern their partitioning in alkaline complexes has relevance well beyond mineral taxonomy. Mont Saint-Hilaire, which has yielded dozens of new species since quarrying began, once again demonstrates its unmatched ability to preserve the chemistry of late-stage fluids in exquisitely rare and structurally intricate minerals, and the mckelveyite group, now spanning five formally described parts, continues to reveal how nature organizes some of the rarest elements in the crust.

Subject of Research: Crystal chemistry and site-specific rare-earth element partitioning in a new mckelveyite-group carbonate mineral

Article Title: Mckelveyite group minerals – Part 5: Bainbridgeite-(NdCe), Na2Ba2NdCe(CO3)6●3H2O, a new neodymium and cerium-dominant species from Mont Saint-Hilaire, Canada

Article References: Lykova, I., Rowe, R., Poirier, G., Friis, H., Ojaste, K., & Barnes, S. (2026). Mckelveyite group minerals – Part 5: Bainbridgeite-(NdCe), Na 2 Ba 2 NdCe(CO 3 ) 6 ●3H 2 O, a new neodymium and cerium-dominant species from Mont Saint-Hilaire, Canada. European Journal of Mineralogy, 38(4), 419-429. https://doi.org/10.5194/ejm-38-419-2026

Image Credits: AI Generated

DOI: 10.5194/ejm-38-419-2026

Keywords: bainbridgeite-(NdCe), new mineral species, Mont Saint-Hilaire, mckelveyite group, rare-earth elements, neodymium, cerium, carbonate mineral, crystal structure, X-ray diffraction, alkaline complex, mineralogy

The challenge the team set out to solve is deceptively simple to state and notoriously hard to engineer around. Plasticizers are small molecules blended into rigid PVC to make it flexible, and their compatibility with the polymer chains is entirely physical rather than chemical. Under cold conditions, the polymer chains lose mobility and the plasticizer can no longer remain uniformly dissolved; it begins to phase-separate, migrating toward surfaces and interfaces. This migration embrittles the material, contaminates whatever the plastic touches, and, in the case of older phthalate plasticizers, raises well-documented toxicological concerns. Conventional inorganic modifiers such as silica and calcium carbonate can slow migration somewhat, but they typically do so at the cost of low-temperature toughness, and most layered double hydroxide research has focused on flame retardancy and thermal stability rather than cold-region flexibility.

The Qinghai group, led by Yongchun Li together with corresponding authors Li Gao and Bingxin Liu, synthesized a magnesium-based layered double hydroxide co-doped with lanthanum and cerium via a straightforward co-precipitation route. Layered double hydroxides, often called hydrotalcite-like compounds, consist of positively charged brucite-like metal hydroxide sheets interspersed with charge-balancing anions and water. Their layered architecture gives them enormous surface area and an ability to form strong interfacial interactions with polymer chains, which is precisely what a plasticizer-locking additive needs. By substituting trivalent lanthanum and cerium ions into the magnesium-based host layers, the researchers tuned the charge density, layer spacing, and surface chemistry of the filler, creating a family of additives with systematically varying La-to-Ce ratios.

The filler was then blended into PVC plasticized with dioctyl terephthalate, or DOTP, a terephthalate ester increasingly favored over legacy phthalates for its improved safety profile. The team then subjected the resulting composites to a battery of tests designed to mimic plateau service conditions. Mechanical tensile testing was performed at minus 40 degrees Celsius, a temperature representative of the harshest winter nights on the Qinghai-Tibet Plateau. Plasticizer migration was quantified through standardized extraction measurements. Low-temperature Raman spectroscopy was used to track what happens to the plasticizer molecules inside the polymer matrix as the material cools, and biosafety assessments were carried out to confirm that the modified materials remain non-toxic.

The results split neatly along the lanthanum-to-cerium ratio, revealing a trade-off that the team could exploit. The composite containing the filler with a La-to-Ce ratio of 1:3 achieved an elongation at break of 456.1 percent at minus 40 degrees Celsius, an extraordinary figure for a plasticized polymer at such temperatures and a direct indication that the filler preserves chain mobility and suppresses the cold-induced phase separation that normally embrittles the material. Conversely, the composite with a 3:1 ratio delivered a 100 percent pass rate in low-temperature impact testing alongside a plasticizer migration rate of just 1.2 percent, meaning the additive effectively locks the DOTP molecules in place even as the material endures mechanical shock in deep cold.

The low-temperature Raman characterization provides the mechanistic thread connecting these observations. Raman spectroscopy probes the vibrational signatures of chemical bonds, and by following the characteristic bands of the terephthalate plasticizer as temperature drops, the researchers could watch the onset of phase separation directly. In unmodified PVC, the plasticizer bands shift and broaden as the molecules cluster together and squeeze out of the polymer matrix. In the La/Ce-doped composites, those signatures remain far more stable, indicating that the layered double hydroxide platelets anchor the plasticizer through interfacial interactions, likely involving hydrogen bonding and coordination between the ester groups and the metal hydroxide layer surfaces. The rare-earth dopants, with their high coordination affinity, appear to strengthen these anchoring sites further.

Just as important as the performance numbers is what the biosafety assessments showed. All of the modified materials passed non-toxicity evaluations, addressing a persistent concern with both plasticized PVC and nanostructured inorganic additives. The literature is full of cautionary studies documenting the health risks of migrating phthalates, from gut-liver axis disruption in animal models to cardiotoxicity in zebrafish embryos, and nanoparticle toxicology remains an active field of scrutiny. By combining a relatively benign terephthalate plasticizer with a non-leaching, non-toxic inorganic filler, the Qinghai team has assembled a formulation in which the two principal chemical-exposure pathways of flexible PVC, plasticizer release and additive leaching, are both constrained.

To move beyond trial and error, the researchers applied response surface methodology, a statistical optimization technique that models how multiple formulation variables interact and maps out the response landscape to locate the optimum. This allowed them to identify the best filler loading and La-to-Ce ratio systematically rather than through exhaustive screening, and it provides a practical recipe that other labs and manufacturers can follow. The approach also makes clear that the two desirable properties, cold flexibility and migration resistance, sit at different points on the composition map, so real-world applications can be tuned toward whichever property matters most, or toward a balanced compromise.

The authors are candid about the limits of the current study. All testing was conducted under single low-temperature simulation conditions; the multi-field coupling of cold, ultraviolet radiation, wind erosion, and large diurnal temperature swings that defines genuine plateau service was not reproduced, and long-term aging was not assessed. The team states that future work will focus on field exposure and multi-environmental aging tests, which will be the true test of whether laboratory performance translates into decades of reliable service on power lines, greenhouses, and buildings at altitude. Even so, the study fills a conspicuous gap. Most layered double hydroxide research on PVC has chased flame retardancy and heat stability, while cold-region flexibility and anti-migration performance have been addressed mainly through new plasticizer chemistry. Demonstrating that a single rare-earth-doped inorganic filler can deliver both properties simultaneously, in a green and scalable co-precipitation process, offers the PVC industry a genuinely new tool for one of the harshest environments its products must survive.

Subject of Research: La/Ce-doped magnesium layered double hydroxide as a multifunctional filler for improving the cold resistance and plasticizer migration stability of flexible PVC

Article Title: La/Ce-doped Mg-LDH for simultaneous cold resistance and plasticizer migration suppression of PVC in high-altitude environments

Article References: Li, Y., Qiao, L., Gao, L., Zhang, P., Wang, H., Wang, W., Zeng, P., Zhang, Y., Tian, Y., Song, X., Chen, X., Liu, B., & Zhang, W. (2026). La/Ce-doped Mg-LDH for simultaneous cold resistance and plasticizer migration suppression of PVC in high-altitude environments. Polymer Bulletin, 83(12), Article 641. https://doi.org/10.1007/s00289-026-06694-x

Image Credits: AI Generated

DOI: 10.1007/s00289-026-06694-x

Keywords: PVC, layered double hydroxide, plasticizer migration, low-temperature flexibility, lanthanum, cerium, rare-earth doping, DOTP plasticizer, high-altitude materials, response surface methodology, biosafety, polymer composites