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The composition, provenance, and genetic mechanism of sediment on different sedimentary units of the East China Sea (ECS) shelf are essential for understanding the depositional dynamics environment in the ECS. The sediments in the northern ECS shelf are distributed in a ring-shaped distribution centered on the southwestern Cheju Island Mud. From the inside to the outside, the grain size goes from fine to coarse. Aside from the "grain size effect", hydrodynamic sorting and mineral composition are important restrictions on the content of rare earth elements (REEs). Based on the grain size, REEs, and clay mineral composition of 300 surface sediments, as well as the sedimentary genesis, the northern ECS shelf is divided into three geochemical zones: southwestern Cheju Island Mud Area (Zone I), Changjiang Shoal Sand Ridges (Zone II -1), Sand Ridges of the East China Sea shelf (Zone II -2). The northern ECS shelf is mostly impacted by Chinese mainland rivers (the Changjiang River and Huanghe River), and the provenance and transport mechanism of sediments of different grain sizes is diverse. The bulk sediments come primarily from the Changjiang River, with some material from the Huanghe River carried by the Yellow Sea Coastal Current and the North Jiangsu Coastal Current, and less from Korean rivers. Among them, surface sediments in the southwestern Cheju Island Mud Area (Zone I) come mostly from the Changjiang River and partly from the Huanghe River. It was formed by the counterclockwise rotating cold eddies in the northern ECS shelf, which caused the sedimentation and accumulation of the fine-grained sediments of the Changjiang River and the Huanghe River. The Changjiang Shoal Sand Ridges (Zone II -1) were developed during the early-middle Holocene sea-level highstand. It is the modern tidal sand ridge sediment formed by intense hydrodynamic action under the influence of the Yellow Sea Coastal Current, North Jiangsu Coastal Current, and Changjiang Diluted Water. The surface sediments mainly originate from the Changjiang River and Huanghe River, with the Changjiang River dominating, and the Korean River (Hanjiang River) influencing just a few stations. Sand Ridges of the East China Sea shelf (Zone II -2) are the relict sediments of the paleo-Changjiang River created by sea invasion at the end of the Last Deglaciation in the Epipleistocene. The clay mineral composition of the surface sediments in the study area is just dominated by the Changjiang River, with the North Jiangsu Coastal Current and the Changjiang Diluted Water as the main transporting currents. [ABSTRACT FROM AUTHOR]

Alloying rare earth (RE) elements is an effective method to improve corrosion resistance of Mg-Al alloy but excessive RE concentration may aggravate galvanic corrosion. In this study, density functional theory calculations are performed to unravel effects of RE (RE = Sc, Y, Nd) concentration on the galvanic corrosion of Mg-Al alloy from the perspectives of work function and surface energy. The results showed that, when the RE concentration was low, the galvanic corrosion between Mg matrix and Mg17Al12 phase could be alleviated with the increasing of RE concentration. When the RE concentration was high, the precipitated RE phases became cathodes and strongly aggravated galvanic corrosion of Mg matrix. Furthermore, regardless of the change of RE concentration, the effectiveness of alleviating galvanic corrosion in Mg-Al alloy was in the order: Sc > Y > Nd. Possible explanations to experiments were provided and potential strategy to improve corrosion resistance of Mg-Al alloy was also proposed.

The addition of rare earth (RE) elements can effectively improve the mechanical properties of Mg alloys, which is attributed to its ability to regulate the plastic deformation behavior of Mg alloys. Here, the effects of the concentration of RE element Y and temperature on the migration behavior of twin boundary (TB) in the Mg alloys are investigated by molecular dynamics simulation. The results show that Y element has a softening effect on the migration of TB and promoted TB migration in the Mg alloys. The higher concentration of Y element, the stronger the softening effect on TB migration, and also the faster the migration speed of TB. The results indicate that higher temperature is beneficial to TB migration, and the softening effect of Y element on TB migration in the Mg alloys decreases with the increase of temperature. In addition, the migration mechanism of TB in the Mg alloys is analyzed in detail. This work provides a theoretical basis for the design and preparation of high-performance Mg alloys.

In this study, scanning electron microscopy (SEM), electron backscatter diffraction analysis (EBSD), and electron probe microanalysis (EPMA) were used to investigate the impact of rare-earth Sc on the interface microstructure and mechanical properties of Al/steel bimetallic composites fabricated by liquid–solid casting. With the addition of 0.3% Sc, the morphology of eutectic Si changed from needle-like to fibrous and granular. The addition of Sc did not change the types of intermetallic compounds in the Al/steel reaction layer, which comprised the Al5Fe2, τ1-Al2Fe3Si3, Al13Fe4, τ5-Al7Fe2Si, and τ6-Al9Fe2Si2 phases. The thickness of the first layer decreased, whereas that of the second layer increased as the Sc content increased to 0.3%. Furthermore, the Al5Fe2 and τ1 phase percentages of the reaction layer decreased, whereas the Al13Fe4, τ5, and τ6 phase percentages increased. Sc was mainly enriched in the front of the ternary compound layer (τ6) near the Al side. The addition of 0.3% Sc reduced the grain size of each phase in the interfacial reaction layer and did not change the preferred orientation of the Al5Fe2, Al13Fe4, τ5, and τ6 phases, but increased the polar density of the Al13Fe4, τ5, and τ6 phases and decreased the polar density of the Al5Fe2 phase. With the addition of 0.3% Sc, the average nanohardness of the reaction layer decreased by 5% and the bonding strength increased by 48%.

In this study, electrochemical deposition was used to synthesize SrS-doped zirconium materials at a varying voltage of deposition. The XRD result shows that SrS/Zr has a prominent peak intensity corresponding to 2theta values of 26.45o, 33.86o, 38.01o, and 51.49o. The crystal lattice is shown by the prominent peak intensity with higher 2theta degree values; the appearance of an unindexed peak is caused by the substrate utilized for the deposition. SrS surface morphology reveals a Clove-like surface with precipitate visible in the SrS micrograph; the large grain size on the surface of the substrate exhibits photon absorption but lacks any signs of pinholes. At the introduction of zirconium as a dopant to the SrS precursor, there was a drastic change in the precursor which is also noticed on the surface micrograph of the analyzed films. The films show a decrease in thickness from 129.14 to 120.09 nm and an increase in film resistivity from 1.24 x 109 to 1.29 x 109 ohm.m, which further led to a decrease in conductivity from 8.06 x 108 to 7.75 x 108 S/m. The impact of the deposition voltage on the reflectance reveals that lower voltage will stabilize the reflectance of SrS/Zr which will be useful for photovoltaic applications. SrS has an energy bandgap of 1.50 eV while SrS/Zr with bandgap energy of 2.00 – 2.50 eV.

Understanding the origins of Tibetan Plateau (TP) glacier dust is vital for glacier dynamics and regional climate understanding. In May 2016, snow pit samples were collected from glaciers on the TP: Qiyi (QY) in the north, Yuzhufeng (YZF) in the center, and Xiaodongkemadi (XDK) in the south. Rare earth element (REE) concentrations were analyzed using inductively coupled plasma mass spectrometry (ICP-MS), and near-surface PM10 concentrations were extracted from a dataset of Chinese near-surface PM10. Two tracing approaches were used: direct REE tracing and an indirect approach combining potential source contribution function (PSCF) and concentration-weighted trajectory (CWT). Both methods yielded consistent results. Pre-monsoon, TP surface soils, Taklimakan Desert, and Qaidam Basin contributed to glacier dust. Notably, central and southern glaciers showed Thar Desert influence, unlike the northern ones. Taklimakan and Thar Deserts were major contributors due to their substantial contribution and high dust concentration. Taklimakan dust, influenced by terrain and westerly winds, affected central and southern glaciers more than northern ones. Westerlies carried Thar Desert dust to the TP after it was uplifted by updrafts in northwest India, significantly affecting southern glaciers. Furthermore, comparing the two tracer methods, the indirect approach combining PSCF and CWT proved more effective for short-term dust source tracing. [ABSTRACT FROM AUTHOR]

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Recent studies have shown that various fern species can accumulate REEs in the soil and may be utilized as indicator plants. Athyrium yokoscense, commonly called hebino negoza in Japan, is a pteridophyte that is used as an indicator of metal-contaminated soils in Japan. Mining and mineral processing increase the potential of mine minerals to oxidize and change their chemical form. A study on the biogeochemical behavior of REEs in the mine area needs to be conducted due to the significant use of REEs as an essential material for various applications in the world. The REE content in sediment and pteridophytes under different mining areas was analyzed by inductively coupled plasma-mass spectrometry. The concentration of REEs contained in Athyrium yokoscense was analyzed and then compared to sediment to determine the ability of the plant to absorb and accumulate rare earth elements in the mine area. Sediment and plant samples were collected from three mining areas: Ikuno mine, Akenobe mine, and Tada mine. Athyrium yokoscense plants were collected and digested with hydrogen peroxide (H2O2) and nitric acid (HNO3) at a ratio of 2:5. Sediment samples were taken and digested by the alkali fusion method using lithium tetraborate and then processed using the conventional column method. The present study determined that the concentration of REEs varies in every location, and light REEs tend to be more abundant in sediments than heavy REEs. The amount that can be transferred to ferns also varies. Athyrium yokoscense in the ex-mining area accumulates proportionately more LREEs than HREEs, specifically in the Athyrium yokoscense leaves. The characteristic of the element significantly contributes to the accumulation of REEs in pteridophytes. [ABSTRACT FROM AUTHOR]

Increasing demand for low carbon technologies and renewable energy sources requires our resources and economies to be circular. Many countries agree that the responsible consumption, production, and recycling of rare-earth-containing products is essential as a way to achieve the sustainable development goals also set out in the European Green Deal. Sustainable sourcing is targeted with carefully designed roadmap for cost efficient REE production from end-of-life products (EoLs) in addition to mining activities as providing primary sources. Hydrometallurgical methods, such as roasting, leaching, precipitation, crystallization, solvent extraction, and ion exchange includes fast developing, selective, eco-friendly, and cost-effective technologies especially for the extraction of REEs. This article provides an overview of primary and secondary resources and summarizes presents case scenario of studies carried out on the use of some promising methods, which could serve as an economical means for recovering REEs. [ABSTRACT FROM AUTHOR]

This study focuses on using the chemical compositions of plagioclase to further investigate the petrogenesis of Chang'E-5 young mare basalts and constrain its parental melt composition. Together with previously published data, our results show that the plagioclase in mare basalts overall displays large variations in major and trace element concentrations. Inversion of the plagioclase data indicates that the melt compositions parental to Chang'E-5 basalts have high rare earth elements (REE) concentrations similar to the high-K KREEP rocks (potassium, rare earth elements, and phosphorus). Such a signature is unlikely to result from the assimilation of KREEP components, because the estimated melt Sr shows positive correlations with other trace elements (e.g., Ba, La), which are far from the KREEP end-member. Instead, the nearly parallel REE distributions and a high degree of trace element enrichment in plagioclase indicate an extensive fractional crystallization process. Furthermore, the estimated melt REE concentrations from plagioclase are slightly higher than those from clinopyroxene, consistent with its relatively later crystallization. Using the Ti partition coefficient between plagioclase and melt, we estimated the parental melt TiO2 content from the earliest crystallized plagioclase to be ~3.3 ± 0.4 wt%, thus providing robust evidence for a low-Ti and non-KREEP origin for the Chang'E-5 young basalts in the Procellarum KREEP terrane. [ABSTRACT FROM AUTHOR]

In this present study, composites of chitosan‐graft‐poly(N‐tertiary butylacrylamide) (CH‐graft‐poly(N‑tert‑BAAm)) copolymer, with Neodymium (Nd), an important rare earth element, were prepared by precipitation technique. Nd was successfully incorporated into the polymer of different weight percentages (0.5%, 1%, and 2%) without any degradation. The effect of neodymium additives on the structural, morphological, and antibacterial activities against gram‐positive bacteria and gram‐negative bacteria of the polymer was analyzed using various instrument techniques. X‐ray diffraction (XRD) results together with Fourier Transform Infrared (FT‐IR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) studies confirmed the morphology of Nd‐doped CH‐graft‐poly(N‑tert‑BAAm) composites without any other impurities. The antibacterial effect of Nd was studied by adding it to the copolymer in a weight ratio of 0.5%–2%. The antibacterial effect of neodymium concentration on four different strains of bacteria was investigated: Escherichia coli (ATCC 25922) (E. coli), Pseudomonas aeruginosa (DSM 50071) (P. aeruginosa), Bacillus subtilis (DSM 1971) (B. subtilis), and Staphylococcus aureus subsp. aureus (ATCC 25923) (S. aureus). The antibacterial activities of the obtained composites were determined using the Agar Well Diffusion Assay Method. Experimental results show that Nd binds well to CH‐graft‐poly(N‑tert‑BAAm). Activity against E. coli, P. aeruginosa, B. subtilis, and S. aureus subsp. aureus creates a potential for pharmaceutical and biomedical applications. [ABSTRACT FROM AUTHOR]

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Ion adsorption-type rare earth element (REE) ore deposits in South China are a major source of heavy rare earth elements (HREE) around the world, which are of considerable economic and strategic significance. In these ores, REE is enriched in the clay minerals, specifically kaolinite and halloysite, which are derived from their parent granitoid by the weathering process. However, the mechanisms of supergene REE mineralization remain unclear. We investigated the nature and origin of supergene REE mineralization, based on a nanoscale study of a typical REE-mineralized granite regolith profile (ΣREEmax = 1201 ppm) in the Dazhou super-large, ion adsorption-type REE deposit, Guangxi Province, South China. Bulk mineralogical and geochemical analyses, coupled with novel nano-characterization techniques [i.e., hollow fiber flow field-flow fractionation inductively coupled plasma-mass spectrometry (HF5-ICP-MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)], were used to determine the nature of the nano-minerals and nanoparticles in the regolith samples. X-ray diffraction and SEM-EDS analyses revealed that ion-adsorption clay minerals are dominated by platy-shaped kaolinite and rod-like halloysite (10 and 7 Å) within the regolith. The average clay mineral contents decreased from 38 to 15% from the fully weathered horizon to the semi-weathered horizon, whereas the proportion of halloysite increased in the clay mineral fraction in the deep horizons. The REE-bearing nanoparticles consist predominantly of macromolecules of organic matter (2–5 nm) and clay minerals (5–40 and 40–80 nm) according to the HF5-ICP-MS analysis. There is a close association between REE and Al contents in particles with sizes of 5–40 nm in the semi-weathered horizons and 40–80 nm in the highly weathered horizons, which indicates that nanoscale clay minerals (halloysite and kaolinite, respectively) are important REE carriers. In addition, nanoscale secondary REE mineral phases, including oxide, silicate, and phosphate, were identified by the SEM and TEM observations. These phases are typically adsorbed onto the surfaces of clay minerals, specifically rod-like halloysite, but have different occurrences in the regolith profile. Cesium-oxide (cerianite) and Ce-silicate (cerite) occur mainly in the upper horizon of the regolith profile, whereas low-crystallinity REE phosphates [rhabdophane-(La)] occur mainly in the lower horizon of the profile. Our results indicate that nano-minerals and nanoparticles affect REE enrichment and fractionation during granite weathering. Migration and accumulation of REE-bearing nano-minerals were caused by leaching and neoformation of REE-bearing nano-minerals during secondary precipitation. These processes contribute to the formation of supergene REE mineralization in granite regolith. [ABSTRACT FROM AUTHOR]

In recent years, there have been efforts to utilize surface water as a power source, material, and food. However, these efforts are impeded due to the vast amounts of contaminants and emerging contaminants introduced by anthropogenic activities. Herbicides such as Glyphosate and Glufosinate are commonly known to contaminate surface water through agricultural industries. In contrast, some emerging contaminants, such as rare earth elements, have started to enter the surface water from the production and waste of electronic products. Duckweeds are angiosperms from the Lemnaceae family and have been used for toxicity tests in aquatic environments, mainly those from the genus Lemna, and have been approved by OECD. In this study, we used duckweed from the genus Wolffia, which is smaller and considered a good indicator of metal pollutants in the aquatic environment. The growth rate of duckweed is the most common endpoint in observing pollutant toxicity. In order to observe and mark the fronds automatically, we used StarDist, a machine learning-based tool. StarDist is available as a plugin in ImageJ, simplifying and assisting the counting process. Python also helps arrange, manage, and calculate the inhibition percentage after duckweeds are exposed to contaminants. The toxicity test results showed Dysprosium to be the most toxic, with an IC50 value of 14.6 ppm, and Samarium as the least toxic, with an IC50 value of 279.4 ppm. In summary, we can provide a workflow for automatic frond counting using StarDist integrated with ImageJ and Python to simplify the detection, counting, data management, and calculation process. [ABSTRACT FROM AUTHOR]

An Al-Zn-Mg-Cu alloy has high specific strength, good corrosion resistance, fracture toughness and fatigue resistance. It is one of the most important structural materials in the fields of aviation, aerospace, weapons and transportation; in particular, it plays a huge role in the field of aerospace. In order to optimize the strength, toughness and corrosion properties of an Al-Zn-Mg-Cu alloy, the focus of research on this alloy has always been on the alloying process. The effects of the main alloying elements, trace alloying elements and rare earth elements on the microstructure and properties of Al-Zn-Mg-Cu alloys are briefly introduced in this paper, and future research directions are proposed. [ABSTRACT FROM AUTHOR]

Microfiber (MF) has a similar structure to natural leather. Four rare earth (RE) elements, La, Ce, Gd, and Er, were loaded onto the surface of microfibers through plant tannins to prepare a wearable microfiber-based X-ray shielding material (RE-MF), and the X-ray shielding performance was tested. The analysis results of ultraviolet absorption spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) indicate that the rare earth elements can be uniformly loaded onto the surface of ultrafine fibers using plant tannins. The test results of X-ray shielding performance show that within the photon energy of 100 keV, the microfiber materials loaded with four rare earth elements have good X-ray shielding performance, and the shielding efficiency is increased with the increase of the loading amount of rare earth element and the thickness of microfiber. In the 20-80 keV energy range, the shielding efficiency of 2.6 mm Gd4-MF is up to 60% against X-rays, nearly equal to that of 0.25 mm lead plate but with non-toxicity, softness and wearability features. The test results of mechanical properties show that the microfiber-based X-ray protective material maintains the original good mechanical properties of microfibers, and is expected to be widely used in the field of X-ray protection.

In this work, effects of rare earth addition on mechanical properties and corrosion behavior of GCr15 bearing steel under hot rolled, annealed, and quenched-tempered conditions were investigated via mechanical tests, electrochemical measurements, and immersion tests. Results show that rare earth elements can refine grains, improve hardness, tensile strength, and impact absorption energy of GCr15 bearing steel under different heat treatment conditions. Besides, it has been found that rare earth elements are beneficial to corrosion resistance of GCr15 bearing steel in 0.1 mol/L NaCl solution by electrochemical and immersion measurements.

By using jasmonic acid (JA) biosynthetic inhibitor ibuprofen (IBU), we investigated the roles of JA in the process of lanthanum nitrate (La(NO3)3)-regulated ascorbic acid (AsA) content and metabolic enzymes responsible for AsA metabolism in strawberry fruit. Findings demonstrated that La(NO3)3 markedly improved AsA content by enhancing the activities and transcript levels of glutathione reductase (GR), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and L-galactono-1,4-lactone dehydrogenase (GalLDH), and inhibiting the activities and transcript levels of ascorbate peroxidase (APX) and ascorbic acid oxidase (AAO). In comparison with La(NO3)3 alone, all the concentrations of IBU plus La(NO3)3 markedly inhibited the activities and transcript levels of DHAR, MDHAR, GalLDH and AAO, and improved the activities and transcript levels of GR and APX, which further reduced AsA content. Besides, La(NO3)3 increased JA content and IBU decreased JA content induced by La(NO3)3. Meanwhile, the results of Pearson correlation analysis showed that JA content had significant correlations with the activities and transcript levels of DHAR, MDHAR and GalLDH. Above findings implied that La(NO3)3 induced JA production, which further increased AsA content in fruits by mainly up-regulating the activities and transcript levels of DHAR, MDHAR and GalLDH.

During the Meishucun period of the Early Cambrian, a large-scale phosphorus formation event occurred on the Upper Yangtze platform. As the product of this event, the sedimentary environment and formation mechanism of phosphorite remains elusive. In order to better understand the sedimentary environment and formation mechanism of phosphorite enrichment, we investigated the geochemical characteristics of phosphorite in Maidiping Formation of Lower Cambrian in Huangjiaping area of Mabian County. The results show that: ΣREE has significant positive correlation with P2O5, and (La/Yb)N and (La/Sm)N ratio are 0.98 ~ 1.61 and 0.93 ~ 1.39, indicating that REE enrichment is affected by early diagenetic adsorption, and the phosphorite retains the original fractionation characteristics of REE. Obvious negative Ce anomalies (average Ce/Ce* is 0.44) and the absence of framboid pyrite in the phosphorite indicating that the phosphorite were deposited under oxic/dysoxic conditions. The high Y/Ho ratio (mean 65) is consistent with the Y/Ho ratio of modern oxygen-containing seawater, indicating that phosphorite is derived from the original oxic seawater. The weak negative Eu anomaly (Eu/Eu* mean value is 0.9) indicates that the formation of phosphorite is not affected by hydrothermal activity. The REE distribution pattern is “hat type”, indicating that the formation of phosphorite is controlled by Fe-redox pump at sea-sediment interface. In combination with the above findings and combined with the highly stratified redox ocean structure and the intensive upwelling in the early Cambrian, the phosphate released during the redox of FeOOH was transported into the shallow water. In the shallow underground burial, phosphate is enriched by biodegradation and reductive release of FeOOH, and finally phosphate and Ca2+ are combined to form apatite, which is continuously enriched and ore-forming.

Kvanefield REE deposit is a world-class REE deposit, which is located at the northern margin of the Ilímaussaq complex in the central part of Gardar igneous province, southwestern Greenland. The intrusion controlling ore is the mesoproterozoic Ilimaussaq complex, where two main varieties of metallogenic parent rocks are distinguished, green aegirine lujavrite and black arfvedsonite lujavrite，which all are agpaitic alkaline rocks, defined as a peralkaline nepheline syenit. The ore bodies are controlled by fractures or interlayer-gliding surfaces, which consist of sodalite lujavrite pegmatite veins and layered arfvedsonite lujavrite. According to mineral assemblage and occurrence form, the ores are divided into arfvedsonite-albite- steenstrupine type and sodalite-aegirine-eudialite type. Specifically, steenstrupine and eudialite are the main bearing rare earth element minerals in the two ores. The steenstrupine have varying ω(REO) contents ranging from 31.5% to 44.9%, with an average of 35.9%, and stone LREE, U and Th enrichment, moreover, which are easily replaced by monazite and uranothorite. In addition, eudialyte have stable ω(REO) contents ranging 1.41% to 1.90%, riching HREE, Nb, and Ta. Two mode of rare earth element occurrence are distinguished in eudialyte, isomorphism and other finely mineral inclusions such as monazite and steenstrupine. With alkaline complex multi-stage diagenesis process of rock mass and alkaline magma in aegirine lujavrite stage of magmatic hydrothermal mineralization and arfvedsonite lujavrite stage magma and mineralization, and form tratiform-lenticular structure on the whole, diagenetic-mineralization model has a different source, multi-stage, with an invasion characteristics.

In order to reveal the formation mechanism of the organic-rich shales of the Shahejie Formation in Nanpu Sag, the depositional environment and provenance were investigated in detail through analyzing trace and rare earth elements(REE) geochemical characteristics. The results show that the trace elements Li, Cs and Bi are enriched, Cr and Sn are relatively depleted, and other trace elements are close to those in the upper continental crust(UCC).The total amount of REE vary widely, which is close to or higher than the average value in the UCC, and the supply of terrestrial source debris is adequate. The REE allocation pattern shows light rare earth element(LREE) enrichment with a high degree of divergence, and a relative deficit of heavy rare earth element(HREE) with a low degree of divergence. Eu negative anomaly is obvious, Ce is basically normal. The variations of Sr abundance and Sr/Ba ratio reflect that, in Nanpu Sag, the lake water was separated to a certain extent, and the fresh water, brackish water and saline water coexisted during sedimentary period of the third member of Shahejie Formation(Es3), and during these dimentary period of the first member of Shahejie Formation(Es1), the connectivity of lake water was enhanced, which was dominated by brackish water.The values of the V/(V+Ni), Th/U, δCe, and Ceanom comprehensively delineate the water body presented suboxic environment with moderate stratification. Respectively, the source Ba content indicated the water body was dominated by high paleoproductivity. The REE assemblage characteristics suggests that the provenance of Shahejie Formation were primarily derived from Yanshanian granites developed in Yanshanian fold belt and a small amount of sedimentary rocks. The development of organic-rich shales in the Shahejie Formation in Nanpu Sag is closely related to paleoenvironment and paleogeography, which can be summarized as the followings: ①suitable paleosalinity as well as sufficient nutrients at water body contributed to the booming of various planktonic algae, improving the production efficiency of the aquatic organic matter; ②suboxic water column slowed down the degradation of oxygen-sensitive material during the burial process, enhancing the preservation efficiency of sedimentary organic matter.

Modern-day devices, transport, and green energy require growing supply of rare earth elements (REEs), which subsequently provide the basics for attempts on developing the efficient and innovative methods for their detection and exploration. Remote sensing data / techniques provide great possibilities to quick and non‑destructive exploration of such deposits, even in relatively unreachable and socially sensitive places. The diagnostic absorption features of REEs are generated in the visible to shortwave infrared (VNIR-SWIR) region of the electromagnetic spectrum, among which, the most prominent absorption features of neodymium (Nd), which could be a key pathfinder for REEs, are displayed in the VNIR region. This study assesses the capability of the Sentinel-2 MSI data for detecting absorption feature of Nd from space. This process was successfully examined and verified in the Esfordi phosphate deposit, Central Iran, and resulted the direct mapping of REE (Nd). For this purpose, firstly, the potential of the Sentinel-2 MSI data for detecting REEs was theoretically evaluated, and then, the adaptive coherence estimator (ACE) algorithm was applied for targeting Nd-bearing zones, using the field spectra of apatite as reference. Field works, X-ray diffraction (XRD), spectroscopy, and the geochemical analyses supported the achievements. The results demonstrated that Sentinel-2 MSI can capably detect the 740 nm absorption band of Nd. Generally, this research attained high overall accuracy of 88.64% for the generated map using in situ collected data for verification.

This study investigated the effects of cerium (Ce) on the growth and fruit quality of strawberries under salt stress. The findings revealed that salt stress markedly enhanced the activities of antioxidant enzymes and increased the contents of malonaldehyde (MDA) and hydrogen peroxide (H2O2) in leaves and the contents of anthocyanins, phenolic compounds, vitamin C (Vc), soluble sugar (SS) and titratable acid (TA) in fruits. Ce markedly improved the activities of ascorbate peroxidase, superoxide dismutase, peroxidase and catalase in leaves and the contents of anthocyanins, phenolic compounds, Vc and SS in fruits, but significantly decreased MDA and H2O2 levels in leaves and TA content in fruits under salt stress. However, salt stress significantly decreased the contents of chlorophyll (Chl) and carotenoids (Car), photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (gs), relative water content (RWC), plant height and biomass, and fruit weight and sugar-acid ratio (SAR). Compared with salt stress alone, Ce obviously increased Chl and Car contents, Pn, Tr, gs, RWC, plant height and biomass, as well as fruit weight and SAR. The above results suggested that Ce showed beneficial effects on the growth and fruit quality of strawberries under salt stress.

Controlling the morphology and composition of Pd-based catalysts is the key to construct highly efficient electrocatalysts for cathodic oxygen reduction reaction (ORR). Here, rare Earth element Y-doped Pd nanosponge (PdY NSs) are prepared by one-step reduction approach using NaBH4 as reductant, which are employed for ORR under 0.1 M KOH. The PdY NSs with plentiful voids can offer a large number of active sites and improve the mass transfer for ORR. Moreover, the introduction of Y alters the electronic structure of Pd, thus promoting the dissociation and adsorption of oxygen. Therefore, the prepared PdY NSs display superior ORR activity and durability to the Pd NSs and Pd black, highlighting the introduction of rare Earth element on the enhancement of ORR performance for Pd-based catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Timings of garnet formation are constrained using garnet-zircon equilibrium. • Multiple garnet-forming metamorphisms are petrochronologically revealed. • A single metamorphism or polymetamorphism are both likely for the garnet formation. The Sør Rondane Mountains (SRM), East Antarctica is located in a key area of Gondwana formation where the East African-Antarctic Orogen and the Kuunga Orogen cross. Timing of peak metamorphism has been considered at ca. 650–600 Ma in the SRM, on which previous tectonic models were built. In this study, timing of garnet-forming metamorphisms is determined using in situ U-Pb dating of zircon and petrochronological approach utilizing distribution coefficient of rare earth elements (D REE) between zircon and garnet and REE patterns of zircon. As a result, we obtained several different periods of garnet-forming metamorphism at ≥600 Ma and ≤580 Ma both from the NE- and SW-terranes. This is the first report of multiple timings of garnet formation detected within single samples from the SRM. The latest garnet formation in each sample is probably caused by regional metamorphism, because the garnets accompany pressure shadows and are wrapped by the penetrative foliation defined mainly by the arrangement of biotite. Therefore, multiple timings of garnet formation during a single metamorphism or polymetamorphism are both likely. In the former case, the SRM may be affected by a single long-lived regional metamorphism. This implies that the regional metamorphism belongs only to the East African-Antarctic Orogeny or that the East African Orogeny continuously transformed into the Kuunga Orogeny in the deep crust. In the latter case, the former regional metamorphism corresponds to the East African(-Antarctic) Orogeny, whereas the latest metamorphism may correspond to the final stage of East African-Antarctic Orogeny or the Kuunga Orogeny. Any temperature drops during these two garnet-forming timings support the polymetamorphism, which needs to be cleared in the future works. [ABSTRACT FROM AUTHOR]

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Background. Analyzing the pollution and health risk of rare earth elements (REEs) in crop-growing soils around rare earth deposits can facilitate the improvement of REE mining-influenced area. In this study, pollution status, fraction and anomaly, plant accumulation characteristics, and potential risks of REEs (including heavy and light rare earth elements, HREEs and LREEs) in C. sinensis planting soil near ion-adsorption deposits in southern Ganzhou were analyzed. The influence of the soil environment on REEs in soil and fruit of C. sinensis was also explored. Methods. The geo-accumulation index (Igeo) and ecological riskindex(RI) were used to analyze the pollution potential and ecological risks of REEs in soils, respectively. Health risk index and translocation factor (TF) were applied to analyze the accumulation and health risks of REEs in fruit of C. sinensis. The influence of soil factors on REEs in soil and fruit of C. sinensis were determined via correlation and redundancy analysis. Results. Comparison with background values and assessment of Igeo and RI indicated that the soil was polluted by REEs, albeit at varying degrees. Fractionation between LREEs and HREEs occurred, along with significant positive Ce anomaly and negative Eu anomaly. With TF values < 1, our results suggest that C. sinensis has a weak ability to accumulate REEs in its fruit. The concentrations of REEs in fruit differed between LREEs and HREEs, with content of HREE in fruit ordered as Jiading > Anxi > Wuyang and of LREE in fruit higher in Wuyang. Correlation and redundancy analysis indicated that K2O, Fe2O3 and TOC are important soil factors influencing REE accumulation by C. sinensis, with K2O positively related and Fe2O3 and TOC negatively related to the accumulation process. [ABSTRACT FROM AUTHOR]

In this study, a sustainable and easily prepared hydrochar from wood waste was studied to adsorb and recover the rare earth element cerium (Ce(III)) from an aqueous solution. The results revealed that the hydrochar contains several surface functional groups (e.g., C–O, C = O, OH, COOH), which largely influenced its adsorption capacity. The effect of pH strongly influenced the Ce(III) removal, achieving its maximum removal efficiency at pH 6.0 and very low adsorption capacity under an acidic solution. The hydrochar proved to be highly efficient in Ce(III) adsorption reaching a maximum adsorption capacity of 327.9 mg g−1 at 298 K. The kinetic and equilibrium process were better fitted by the general order and Liu isotherm model, respectively. Possible mechanisms of Ce(III) adsorption on the hydrochar structure could be explained by electrostatic interactions and chelation between surface functional groups and the Ce(III). Furthermore, the hydrochar exhibited an excellent regeneration capacity upon using 1 mol L−1 of sulfuric acid (H2SO4) as eluent, and it was reused for three cycles without losing its adsorption performance. This research proposes a sustainable approach for developing an efficient adsorbent with excellent physicochemical and adsorption properties for Ce(III) removal. [ABSTRACT FROM AUTHOR]

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To enhance the overall performance of perovskite solar cells, the quality of the electron transport layer (ETL) held significant importance. Zinc oxide (ZnO) emerged as highly promising due to its exceptional optical and electrical characteristics. This study included the incorporation of lanthanum (La III) into the ZnO lattice to improve its optoelectronic properties. All the produced thin films were crystallized at low annealing temperatures. Through careful analysis, it was observed that the inclusion of doping with 4% La (III) resulted in increased crystallinity, leading to low surface roughness. Additionally, this doping strategy facilitated enhanced mobility of charge carriers and conductivity.

Rare earth elements (REEs) are a new type of material resource which have attracted significant attention in recent years. REEs have emerged as essential metals in modern-day technology due to their unique functions. The long-term, large-scale mining and utilization of rare earths has caused serious environmental pollution and constitutes a global health issue, which has raised concerns regarding the safety of human health. However, the toxicity profile of suspended particulate matter in REEs in the environment, which interacts with the human body, remains largely unknown. Studies have shown that REEs can enter the human body through a variety of pathways, leading to a variety of organ and system dysfunctions through changes in genetics, epigenetics, and signaling pathways. Through an extensive literature search and critical analysis, we provide a comprehensive overview of the available evidence, identify knowledge gaps, and make recommendations for future research directions.

The Daggyai hydrothermal area (Tibet) is located on the southern margin of the Lhasa-Gangdise terrane and adjacent to the middle of the Indus-Tsangposuture. Acid, neutral, and weakly alkaline hot springs are ubiquitous in Daggyai, offering a peerless opportunity to study the distribution of rare earth elements (REE) in various geothermal waters as well as their geochemical origins. In this study, different types of the Daggyai hot springs were systematically collected to determine their REE concentrations, to discern the REE patterns and to calculate the REE speciation, which is helpful for revealing the indications of the geochemical behavior of REEs in high-temperature geothermal environments. The results of the study show that the REEs in the Daggyai hot springs behaved conservatively, with their concentrations being affected by the sorption of Fe-or Al-rich minerals or amorphous phases instead of sulfate minerals, and the REE patterns and speciation were controlled by the redox conditions and fluid-rock interactions in the reservoirs, capable of reflecting the geological genesis and the general hydrochemical characteristics of the hot springs. Although the major constituent hydrochemistry of the Daggyai hot springs demonstrates that the reservoir host rocks are primarily felsic rocks, the negative Ce anomaly of the neutral-to-alkaline hot springs implies that there are possibly carbonate rocks in the Daggyai reservoirs. This work is a typical example of relevant studies on REE geochemistry in high-temperature hot springs.

The Zhijin phosphorite (P)-bearing rare earth element (REE) deposit in Guizhou Province (China) hosts vast ore resources (P: 1.348 billion tonnes; REE: 1.44 Mt). Up to date, the Zhijin phosphorite resource has not been exploited because of the uncertain occurrence of the associated REEs, which hampers mineral processing and extraction. In this study, the structure, the valence state, and the coordination position of Y in the REE-yttrium-rich bioclastic samples from Zhijin were revealed by means of synchrotron radiation X-ray absorption fine structure analysis. The results show that the Y occurs as Y(iii) in the samples, and that the form of Y is different from the Y2O3 form in standard xenotime samples. Yttrium in the samples was in a complex coordination position without Y–O–Y bonding, and the Y–O bond lengths range widely without clear patterns. We suggest that Y in the samples is surrounded by organic or macro-molecular compounds, rather than in inorganic ones. Thus, Y in collophanite is unlikely to be in the form of isomorphism.

This mini review article summarizes the recent progress in the modification of Ni-rich cathode materials for Li-ion batteries using rare earth elements. Although layered materials with high nickel content are the most promising cathodes due to their high capacity, the significant chemical, structural and thermal instability considerably hinders their practical application. Overcoming these limitations is possible through morphological or structural modifications based on doping and coating. Numerous reports regarding the use of various elements of the periodic table for this type of modification can be found in the literature. Surprisingly, rare earth elements are the least applied and described in the literature so far, even though they possess all the necessary features qualifying them as effective modifiers of layered cathode materials. This work summarizes the up-to-date publications regarding the application of rare earth elements as a highly prospective group of modifiers for layered Ni-rich cathode materials. These reports provide a better understanding of mechanisms of modification by rare earth elements and their beneficial effects on the electrochemical performance of the studied materials. New prospective strategies for layered cathode materials improvement have also been indicated.

Background: Magnesium alloys (Mg-alloys) have gained significant attention in recent years as a potential bioactive material for clinical applications. The incorporation of rare earth elements (REEs) into Mg-alloys has been of particular interest due to their potential to improve both mechanical and biological properties. Although there are diverse results in terms of cytotoxicity and biological effects of REEs, investigating the physiological benefits of Mg-alloys supplemented with REEs will help in the transition from theoretical to practical applications.Methods: In this study, two culture systems were used to evaluate the effects of Mg-alloys containing gadolinium (Gd), dysprosium (Dy), and yttrium (Y): human umbilical vein endothelial cells (HUVEC) and mouse osteoblastic progenitor cells (MC3T3-E1). Different compositions of Mg-alloys were assessed, and the effects of the extract solution on cell proliferation, viability, and specific cell functions were analyzed.Results: Within the range of weight percentages tested, the Mg-REE alloys did not exhibit any significant negative impacts on either cell line. Interestingly, moderate compositions (Mg-1.5Gd-1.5Dy-0.825Y-0.5Zr and Mg-2Gd-2Dy-1.1Y-0.5Zr) demonstrated a tendency to enhance osteoblastic activity and promote the vascularization process in both HUVEC and MC3T3-E1 cell lines.Discussion: The results of this study provide valuable insights into the potential benefits of REE-supplemented Mg-alloys for clinical applications. The observed enhancement in osteoblastic activity and promotion of vascularization processes suggest that optimizing the compositions of REEs in Mg-alloys could lead to the development of novel, more effective bioactive materials. Further investigations are required to understand the underlying mechanisms and to refine the alloy compositions for improved biocompatibility and performance in clinical settings.

The influence of rare earth (RE) elements on the microstructure and mechanical performance of an extruded ZK60 Mg alloy was studied. Two types of RE elements were added to a ZK60 material and then extruded at a ratio of 18:1. The first new alloy contained 2 wt% Y while the second one was produced using 2 wt% Ce-rich mischmetal. The microstructure, the texture, and the dislocation density in a base ZK60 alloy and two materials with RE additives were studied by scanning electron microscopy, electron backscattered diffraction, and X-ray line profile analysis, respectively. It was found that the addition of RE elements caused a finer grain size, the formation of new precipitates, and changes in the initial fiber texture. As a consequence, Y and Ce-rich RE elements increased the strength and reduced the ductility. The addition of these two types of RE elements to the ZK60 alloy decreased the work hardening capacity and the hardening exponent mainly due to grain refinement. [ABSTRACT FROM AUTHOR]

In the Mardin-Mazıdağı region, which corresponds to the northern Arabian Plate, layers containing marine phosphorite rocks are found within the karababa Formation (Upper Cretaceous). The Karataş member contains phosphorites and carbonate rocks with nodular chert geodes and fossils. The phosphorite and micritic limestones contain invertebrate fossil fragments and materials such as optical isotropic pelletic apatite minerals, angular/subangular and plated fish bone fragments, and brachiopod shells. Sem (scanning electron microscopy) results show that the apatite minerals are either spherical or ellipsoidal in shape and their size varies between 100-200 µm. According to X-ray diffraction (XRD) examinations, the rocks contain apatite (carbonate rich fluorapatite; CFA), carbonate (calcite, dolomite), silica (quartz and opal-CT), little feldspar, and clay (smectite, palygorskite/ sepiolite, kaolinite, illite, chlorite, mixed layered chlorite-vermiculite (C-V) and illite-vermiculite (I-V). The average major and trace elements found in the phosphorite include P2O5 (35.41 wt.%), Rees (44.57 ppm), Y (52.85 ppm), and U (5.45 ppm). The Mazıdağı phosphorite analysis indicates that the conditions are slightly oxic, which is supported by their slightly negative Ceanom average values (-0.30), low Ce/La ratios (0.32), and a V/(V + Ni) mean of 0.93 ppm. All the recoded values of the average REE for the study area are considerably lower than those in Iraq (84.30 ppm), Tunisia (400.3 ppm), morocco (571.75 ppm) and Jordan (187 ppm). It is inferred that mineral formation processes are affected by the biogenic and biogeochemical activities that occurred in conjunction with the changes in sea level driven by the tectonic conditions associated with the evolution of the Neotethys Ocean. [ABSTRACT FROM AUTHOR]

The influence of Er3+ ions on the optical properties of phosphate glasses doped by a fixed concentration of Sm+3 ions had been investigated. Optical absorption studies were executed to estimate the energy gap and Urbach energy. Judd–Ofelt, J–O, model has been applied to the absorption peaks for Er3+ (4f11) transitions to determine the J–O intensity parameters Ωt (t = 2, 4, 6). Using the calculated J–O parameters, the radiative transition probabilities (Ar), Branching ratios (Br), and radiative lifetime (τr) of various excited states of Er3+ ion have been calculated. The studied photoluminescence spectra under an ultraviolet excitation wavelength (380 nm) showed several visible emission bands confirming the down-conversion process. Energy transfer (ET) from 4S3/2 (Er3+) to 4G5/2 (Sm+3) was affirmed. An intensive green emission peak due to 4S3/2 → 4I15/2 transition had been observed with stimulated emission cross-section of 7 × 10–21 cm2. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The EV31A magnesium alloy has the potential for use in aerospace and automotive applications. To ensure the longevity of magnesium and its alloys in final applications, it is essential to know how quickly they corrode. An electrochemical approach (Tafel extrapolation and EIS) was used to evaluate the corrosion behaviour of EV31A alloy in various electrolytic mediums, including 0.6 M NaCl, 0.05 M H2SO4, 0.1 M HNO3, and 0.1 M HF. In each electrolytic solution, the stir-cast, T4, and T6 heat-treated samples corroded electrochemically. The as-cast EV31A alloy has superior corrosion resistance than T4 (solutionising) and T6 (solutionising cum age hardened). Because intermetallic precipitates have a large volume percentage in as-cast, it offers excellent corrosion resistance due to micro-galvanic or localised corrosion. In EV31A, chloride and fluoride ions have the same impact as compared with sulphate and nitrate ions. The as-cast EV31A shows a corrosion rate of 0.03 mm/year in solution containing 0.6 M NaCl and 0.1 M HF. The EV31A is analysed in electrolytes such as 0.6 N NaCl, 0.1 N H2SO4, HNO3, and HF. The electrochemical techniques such as Tafel method and EIS used to analysis the rate of corrosion. Stir-cast EV31A Mg alloy shows better corrosion resistance in all test conditions. [ABSTRACT FROM AUTHOR]

To obtain better hot corrosion resistance for superheater tube material (TP347H), different wt% of cerium oxide (CeO2) powder (0.4 wt%, 0.8 wt%, and 1.2 wt%) was blended with Cr3C2–NiCr and formulated on TP347H substrate with HIPOJET-2700 thermal spray gun. The comparative effect of different contents of Ce on corrosion and erosion behaviour was studied by weight change measurements, and X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and X-ray mapping tools were used to examine corrosion products. The results show that the appropriate addition of cerium oxide can reduce scale spallation and microporosity and enhance the microhardness and surface roughness of the composite coating. Cr3C2–NiCr coatings with and without the addition of CeO2 successfully protected the substrate steel, which might be due to the development of a dense and continued oxide scale composed of Cr2O3 and NiCr2O4. Moreover, it is observed that the addition of CeO2 with 0.4 wt% concentration enhanced the degradation resistance of the Cr3C2–NiCr coating, which might be attributed to the rapid growth of oxide scale on the coating surface, which blocks the penetration of corroding species. Furthermore, the addition of CeO2 also retards the diffusion between substrate and coating. [ABSTRACT FROM AUTHOR]

the results of a study of the galvanomagnetic properties of indium arsenide grown by liquid-phase epitaxy are presented. It is shown that the use of the rare earth element holmium in the growth of InAs epitaxial layers makes it possible to reduce the electron concentration by two orders of magnitude to n = 2.1 × 1015 cm–3 at T = 77 K. This effect is due to the gettering of shallow background impurities with the formation of their compounds in the melt. With an increase in the holmium content of more than 0.12 mol % the concentration of current carriers in the material begins to increase, while mobility decreases due to the influence of VAs–Ho donor centers. This method of gettering is promising for obtaining A3B5 materials with a low concentration of current carriers, which are in demand in the optoelectronic industry. [ABSTRACT FROM AUTHOR]

Chromatographic separation of rare earth elements (REE) as anionic complexes with chelating aminopolycarboxylate ligand methylglycine N,N-diacetate (MGDA) was studied experimentally. A synthetic mixture of La, Nd, and Eu were used to model a REE mixture obtained from processed secondary sources such as phosphogypsum (PG). In the REE extraction from PG, the REEs can be recovered with MGDA to obtain the REE–MGDA mixture. Three strong base anion exchange resins (Dowex 1X8, IRA-402, and IRA-410) were used as the separation materials. Successful separation of the REEs by elution with dilute HNO3 and HCl was attributed to differences in the stabilities of the REE–MGDA complexes. The pKa values of the complexes were determined by titration to be 3.81, 3.25, and 2.96 for La, Nd, and Eu, respectively. Fractionation of the ternary La-Nd-Eu mixture (with a 1:1:1 mole ratio) were studied. La was recovered at approximately 80% purity and 80% yield, but strong trade-offs between the yield and the purity of Nd and Eu must be made. Chromatographic separation was found to be an efficient process option, considering its simplicity and the recovery of several product fractions. The initial process design offers a promising starting point for investigating more advanced process configurations for the efficient recovery of pure REE from phosphogypsum. [ABSTRACT FROM AUTHOR]