Rare Earth Research Articles

Association between concentrations of rare earth elements in chorionic villus and risk for unexplained spontaneous abortion

Rare earth elements (REEs) exposure during pregnancy may increase the risk of unexplained spontaneous abortion. However, the association between REEs intrauterine exposure and unexplained spontaneous abortion had yet to be studied. In order to conduct this large case-control study, we thus collected chorionic villus from 641 unexplained spontaneous abortion and 299 control pregnant women and detected the concentrations of 15 REEs by inductively coupled plasma mass spectrometer (ICP-MS). Because the detection rates of 10 REEs were less than 80%, the remaining 5 REEs, which were lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd) and yttrium (Y), underwent to further analysis. The association between 5 REEs and unexplained spontaneous abortion was assessed by using the logistic regression, bayesian kernel regression (BKMR) and weighted quantile sum regression (WQS) models. In the adjusted logistic regression model, Pr, Nd and Y enhanced the incidence of unexplained spontaneous abortion in a dose-dependent way and Ce increased the risk only at high concentration group. The result of BKMR model demonstrated that the risk of unexplained spontaneous abortion increased as the percentile of five mixed REEs increased. Y and Nd were both significantly associated with an increased incidence of unexplained spontaneous abortion, but La was correlated with a decrease in the risk of unexplained spontaneous abortion. Pr was substantially associated with an increase in the risk of unexplained spontaneous abortion when other REEs concentrations were fixed at the 25th and 50th percentiles. According to WQS regression analysis, the WQS index was significantly associated with unexplained spontaneous abortion (OR = 3.75, 95% CI:2.40–5.86). Y had the highest weight, followed by Nd and Pr, which was consistent with the analysis results of our other two models. In short, intrauterine exposure to REEs was associated with an increased risk of unexplained spontaneous abortion, with Y, Nd and Pr perhaps playing an essential role.

A distinctive rare earth element signature for pyrite oxidation and glacial weathering

The application of rare earth elements (REE) and neodymium (Nd) isotopes to authigenic Fe-(oxyhydr)oxide phases leached from marine sediments can be used for reconstructing past ocean circulation and chemical weathering patterns on nearby continental landmasses. To explore the behaviour of REE during chemical weathering in glacial environments, we analyzed the authigenic fraction of glacimarine sediments from the continental shelf off northern Svalbard (Arctic Ocean), where the evolution of ice sheet dynamics since the last deglaciation is well constrained. Our results show that leached authigenic fractions in Svalbard sediments exhibit shale-normalized REE patterns characterized by anomalously high mid-REE enrichment relative to both light- and heavy-REE, as expressed by concavity index values (CI > 2.5) that significantly depart from typical REE signatures for leached fractions in marine and river sediments worldwide. Using a compilation of literature data, we provide compelling evidence that the occurrence of pronounced mid-REE enrichment in authigenic fractions of Svalbard marine sediments links to terrestrial oxidation of pyrite following glacial weathering. While future investigation will be required to further understand the detailed mechanism accounting for the observed REE decoupling and its link to pyrite oxidation, we propose that preferential dissolution of mid-REE-enriched rock-bearing minerals such as apatite following glacial erosion, sulfide weathering and subsequent release of sulfuric acid could release a distinctive REE signature in glacial surface environments. Our findings suggest that the use of authigenic REE in the sedimentary record could provide a means for tracing glacial weathering and associated biogeochemical sulfur and iron cycling across geological times.

Distribution analysis of rare earth elements in fine‐grained CAIs of the Allende meteorite using multiple‐spot femtosecond LA‐ICP‐MS

ABSTRACTCalcium–aluminum‐rich inclusions (CAIs) in chondrites are one of the oldest materials in the solar system. Presence of refractory minerals in CAIs suggests that they formed thorough a condensation process from nebular gas of solar composition. In particular, fine‐grained CAIs (FGs) have escaped melting after condensation, and thus, the elemental distribution of rare earth elements (REEs) in FG minerals provides key information for elucidating the condensation processes. Although the REE abundances of FG fragments have been investigated in previous studies, the distribution of REEs in individual FG constituent minerals remains poorly explored. Here, we demonstrate the utility of laser imaging of REE distribution in CAIs by analyzing five FGs found in the Allende CV3 chondrite using multiple‐spot femtosecond laser ablation (msfsLA)‐ICP‐MS. The msfsLA‐ICP‐MS imaging system allows for a rapid acquisition of a wider range of REE distributions than previously achieved by Secondary ion mass spectrometry‐based imaging techniques. Out of the five FGs examined in this study, three showed the homogeneous REE patterns, while the other two indicated variable REE patterns within each FG. These observations presumably reflect differences in the chemical processes experienced by the FGs, and indicate that multi‐step chemical processes were recorded in some of the FGs. The msfsLA‐ICP‐MS imaging technique can characterize the elemental distribution of individual FGs under the comparable spatial resolution with high‐analysis throughput, and thus, it is an effective new method for advancing the taxonomy of FGs, which will improve our understanding of the physicochemical conditions that prevailed in the early solar system.

Strontium isotopes and rare earth elements in terrestrial hot-spring deposits: Characterization and geothermal implications

Identifying geothermal reservoir rock types is fundamental in geothermal exploration, but the absence of active surface geothermal manifestations (especially hot springs) in blind geothermal systems makes this identification difficult. Nevertheless, blind geothermal systems may develop early-formed hot-spring deposits. As (bio-)chemical precipitate, these deposits may retain geochemical signatures of spring waters and thus provide insights into reservoir rock types. To assess their geothermal implications, the 87Sr/86Sr and rare earth elements + yttrium (REE + Y) characteristics of hot-spring deposits in two geothermal systems were investigated and compared with those of their reservoir rocks. Results showed relatively uniform 87Sr/86Sr values in hot-spring deposits within each system, but occasional 87Sr/86Sr contamination induced by exogenous detritus input was also observed. The amount of detritus input relates to the potential for interaction with surrounding soils/rocks and is thus environmentally controlled. Hot-spring deposits with high Sr concentrations showed greater 87Sr/86Sr contamination resistance than those with low Sr concentrations, revealing the influence of Sr concentration in hot-spring deposits on detrital 87Sr/86Sr contamination. The detritus input also influenced the REE + Y signatures of the hot-spring deposits, underscoring the necessity of contamination assessment before geochemical interpretation. Excluding samples with significant 87Sr/86Sr and/or REE + Y contamination, the remaining samples closely mirrored their respective reservoir rocks in terms of 87Sr/86Sr, with partial overlap in REE + Y signatures. This suggests that the 87Sr/86Sr and REE + Y characteristics of hot-spring deposits provide valuable insights into reservoir rock types. However, variations in 87Sr/86Sr or REE + Y compositions between some hot-spring deposits and corresponding reservoir rocks indicate additional influencing factors beyond reservoir rock types. Therefore, a comprehensive understanding of reservoir rock types requires integrated geochemical characterization, probably including 87Sr/86Sr, REE + Y, and other parameters. These findings underscore the potential of geochemical characterization of hot-spring deposits for identifying geothermal reservoir rock types, and this geochemical approach can complement geological and geophysical data to improve exploration efficiency, especially in blind geothermal systems.

Two-dimensional Sb net generated nontrivial topological states in SmAgSb2 probed by quantum oscillations

Abstract The REAgSb2 (RE = rare earth and Y) family has drawn considerable research interest because the two-dimensional Sb net in their crystal structure hosts topological fermions and hence rich topological properties. We report herein the magnetization and magnetotransport measurements of SmAgSb2 single crystal, which unveil very large magnetoresistance and high carrier mobility up to 6.2×103% and 5.58×103 cm2V-1s-1, respectively. The analysis of both Shubnikov-de Haas and de Haas-van Alphen quantum oscillations indicates nontrivial Berry phases in the paramagnetic state while trivial Berry curvature in the antiferromagnetic state, indicating a topological phase transition induced by the antiferromagnetic order. It is also supported by the first-principles calculations. The results not only provide a new interesting topological material but also offer valuable insights into the correlation between magnetism and nontrivial topological states.

Fabrication of rare earth (Tb+3) and alkaline earth metal (Mg+2) Co-doped CdAl2O4@MXene composite: A unique approach to tune bandgap energy through quantum confinement effect for photocatalytic applications

The present work includes the use of effective strategy to improve the photocatalytic degradation activity of CdAl2O4 via dopant assimilation to enhance the bandgap energy (Eg) and to influence the light-sensitive activity of this spinel mixed oxide. In this study, CdAl2O4 (CA), Mg–CdAl2O4 (MCA), and Tb-doped Mg–CdAl2O4 (TMCA) were fabricated by the facile co-precipitation route and an ultra-sonication approach was used to prepare a composite of Tb-doped Mg–CdAl2O4 with MXene (TMCA@MXene). The obtained results from UV–Visible analysis deduce that there is an increase in Eg of MCA (2.51 eV) and TMCA (2.67 eV) as compared to pure CA (2.45 eV) which follows the quantum confinement effect accompanying the decrease in crystallite sizes of doped samples as compared to CA. The significant increase in bandgap energy of TMCA is due to the confinement of electrons in a small area and also due to the conversion of continuous energy levels into discrete energy levels. Moreover, UV–Visible spectroscopic analysis was made to evaluate the catalytic performance of fabricated photocatalysts against harmful organic pollutants. The photocatalytic study showed that the co-doped CdAl2O4 (TMCA) is a better photocatalyst than MCA and CA for the degradation of selected pollutants. Among all synthesized catalysts i.e. CA, MCA, TMCA, and TMCA@MXene, the highest photocatalytic activity was shown by MXene based nanocomposite. TMCA@MXene showed ∼86 % degradation of Rhodamine B (RhB) and 79.6 % degradation of Aspirin (acetylsalicylic acid). The outstanding photocatalytic efficacy of TMCA@MXene could be accredited to the quantum confinement effect produced by co-doping of alkaline earth metal (Mg+2) and rare earth metal (Tb+3) and large surface area, high conductivity, and excellent light harvesting capability provided by MXene sheets. Hence, TMCA@MXene could be an effective photocatalyst in future for the removal of toxic organic pollutants.

Effect of gas protection on form and microstructure of wire arc additive manufactured WE43 magnesium alloy

In this study, WE43 magnesium alloy was successfully fabricated using wire arc additive manufacturing technology, focusing on reducing the common oxide inclusion defects. The implementation of a gas shielding hood significantly improved the grain morphology of the deposited samples and diminished both the quantity and size of oxides. In addition, the cooling effect induced by the shielding gas contributed to the refinement of grain size. The synergistic effect of oxide reduction and grain refinement significantly improves the mechanical properties of the deposited samples. For heat treatable magnesium alloys, minimizing the consumption of rare earth elements is beneficial for optimizing heat treatment mechanical properties.

Rare Earth Interface Structure Materials: Synthesis, Applications, and Mechanisms

Rare Earth Interface Structure Materials: Synthesis, Applications, and Mechanisms

Screw dislocation growth defects enhancing electromagnetic wave absorption performance of GdB6

In this study, a purity of up to 98.36 wt. % GdB6 with screw dislocation growth morphology were successfully fabricated using an in-situ reaction approach. The terraced-like structure of the GdB6 enhanced the interfacial polarization and multiple interface scattering of the electromagnetic waves. As a result, the as-obtained high purity GdB6 powder presented superior electromagnetic wave absorption performance. The minimum reflection loss value can be −49.24 dB at the frequency of 13.12 GHz with a thin matching thickness of 1.44 mm. In addition, the widest effective absorption bandwidth can be up to ∼4 GHz (14–18 GHz) with a thin matching thickness of 1.25 mm. The remarkable electromagnetic wave absorption performance of GdB6 ceramics could be attributed to conductance loss and polarization loss enhanced by the screw dislocation growth defects, as well as synergistic effects with magnetic loss. The as-obtained GdB6 with synergistic dielectric loss and magnetic loss is to be a novel single-phase with excellent electromagnetic wave absorbing material, which will pave the way on the investigation of rare earth hexaborides for the ultra-high temperature environment applications.

Strategy for co-enhancement of corrosion resistance-strength of Cu-7Ni-3Al-1Fe-1Mn alloy: Rare earth Sm microalloying

Both high strength and superior corrosion resistance are necessary for Cu-Ni alloys when serving in marine engineering. We discover that the corrosion resistance and strength of Cu-7Ni-3Al-1Fe-1Mn alloy can be enhanced via rare earth Sm microalloying. When Sm content is 33 ppm, the alloy exhibits not only the lowest corrosion rate, which is 40% lower than the Sm-free alloy, but also the maximum tensile strength, which is 6% higher than the Sm-free alloy. After alloying 33 ppm Sm, the average grain size of Cu-7Ni-3Al-1Fe-1Mn alloy is reduced by 42%, from 205 μm to 118 μm. In addition, CuSm phase and (Sm2S3-Al2O3) composite phase appear in the alloy after alloying 33 ppm Sm. The improvement of corrosion resistance is primarily due to the formation of Cu-Sm precipitates, leading to a positive shift of the corrosion potential. Further analysis indicates that the increased strength can be mainly attributed to grain refinement and the formation of Sm-S precipitations. This work promotes a new method for enhancing the strength and corrosion resistance simultaneously of copper alloy.

The origin of exceptionally large ductility in molybdenum alloys dispersed with irregular-shaped La2O3 nano-particles

Molybdenum and its alloys are known for their superior strength among body-centered cubic materials. However, their widespread application is hindered by a significant decrease in ductility at lower temperatures. In this study, we demonstrate the achievement of exceptional ductility in a Mo alloy containing rare-earth La2O3 nanoparticles through rotary-swaging, a rarity in Mo-based materials. Our analysis reveals that the large ductility originates from substantial variations in the electronic density of states, a characteristic intrinsic to rare-earth elements. This characteristic can accelerate the generation of oxygen vacancies, facilitating the amorphization of the oxide-matrix interface. This process promotes vacancy absorption and modification of dislocation configurations. Furthermore, by inducing irregular shapes in the La2O3 nanoparticles through rotary-swaging, incoming dislocations interact with them, creating multiple dislocation sources near the interface. These dislocation sources act as potent initiators at even reduced temperatures, fostering diverse dislocation types and intricate networks, ultimately enhancing dislocation plasticity.

Occurrence of rare earth elements in umbilical cord serum and association with thyroid hormones and birth outcomes in newborns

Rare earth elements (REEs) are emerging contaminants that are increasingly used in high technology products. However, limited information is available regarding exposure to REEs and associated health effects in neonates. This study aimed to investigate the association between REE concentrations and thyroid hormone levels, as well as birth outcomes in 109 newborns in Beijing, China. We measured the concentrations of 16 REEs and thyroid hormones in umbilical cord serum. To assess the impact of exposure to individual REEs and REE mixtures on thyroid hormone levels and birth outcomes, we employed univariate linear regression, least absolute shrinkage and selection operator (LASSO), and weighted quantile sum (WQS) models. We detected 14 REEs at high rates (92.6%–100%), with yttrium exhibiting the highest median (interquartile range) concentration [43.94 (0.33–172.55) ng/mL], followed by scandium [3.64 (0.46–11.15) ng/mL]. Univariate analyses showed that per logarithmic (ln)-unit change of neodymium (Nd) and samarium (Sm) was associated with 0.039 [95% confidence interval (CI): 0.001, 0.007] and 0.031 (95% CI: 0.003, 0.060) increases in free thyroxine (FT4) levels, respectively. Moreover, 14 REEs exhibited significant associations with triiodothyronine (T3) levels, resulting in increases ranging from 0.066 to 0.307. Elevated concentrations of terbium (Tb) [per ln-unit change: −0.021 (95% CI: −0.041, −0.01)] and lutetium (Lu) [-0.023 (95% CI: −0.043, −0.002)] were inversely correlated with birth length in newborns. A further multiple exposure analysis employing the LASSO model identified Sm, Nd, Y, Sc, and Lu as critical factors influencing FT4 and T3 levels. Additionally, WQS analyses showed positive associations between exposure to a mixture of 14 REEs and FT4 (P = 0.046), T3 (P < 0.001), and birth length (P = 0.049). These findings suggest that in utero exposure to REEs might disrupt thyroid hormone homeostasis and impact intrauterine growth. Further studies are warranted to validate these findings and elucidate the underlying mechanisms.

Effects of doping with selected rare-earth elements (Eu3+, Dy3+, Eu3+/Dy3+) on the structural characteristics as well as electrical and luminescent properties of K0.5Na0.5NbO3

The effects of adding Eu3+, Dy3+, and Eu3+/Dy3+ rare-earth elements on the microstructural, optical and electrical properties of lead-free piezoelectric materials based on K0.5Na0.5NbO3 (KNN) were investigated. A series of fine powders were synthesized via a modified Pechini route utilizing citric acid. Relatively large amounts of rare-earth elements were successfully incorporated into the crystal lattice of KNN. A combination of X-ray diffraction, X-ray absorption spectroscopy, energy-dispersive X-ray and scanning electron microscopy were used to characterize the structure and chemical composition of the powders and sinters. XRD patterns indicated the formation of a single-phase orthorhombic structure in the co-doped sinter. X-ray absorption spectroscopy revealed the nominal 3+ valence states of Eu and Dy in KNN ceramic sinters. The Mott model and group symmetry theory were used to discuss the characteristics of Raman spectra obtained for the EuDy:KNN ceramics. The ceramics exhibited good dielectric permittivity (ε≃1300) and low dielectric loss (tan δ=0.03) in the temperature range of 170–240°C. The electrical properties of the ceramics showed that the basic mechanism of conduction and relaxation was thermal activation, and that small polaron hopping was responsible for charge carrying. The Eu3+ and Dy3+ ions displayed characteristic red and orange emissions in sinters when excited with light in the wide ultraviolet spectra range (380–420 nm).

Enhancement of alpha/beta ratio in NaI:Tl,6Li neutron-gamma scintillators by rare earth co-doping

NaI:Tl,6Li bulk crystals are regarded as promising neutron-gamma (n-γ) scintillators because of low production cost and superior n-γ pulse shape discrimination (PSD) performance. In this work, some rare earth elements (Gd, Y, Lu and Sc) co-doped NaI:Tl,6Li single crystals were grown by the multi-ampoule Bridgman method. It was found that the rare earth co-doping significantly improves the pulse height discrimination (PHD) capability of NaI:Tl,6Li with high alpha/beta (α/β) ratio, approaching to 100%. The optimal α/β ratios achieved for Gd, Y, Lu and Sc co-doped NaI:Tl,6Li are 0.85, 0.93, 0.95, and 0.83, respectively. Electron equivalent energy per neutron interaction is above 3.96 MeV and can be as high as 4.54 MeV, close to the Q value of 4.78 MeV for 6Li(n, α)3H interaction. Moreover, the rare earth co-doped NaI:Tl,6Li crystals still maintain the superior PSD capability with figure of merit (FoM) in the range of 2.1–3.3. These results highlight the great potential of rare-earth co-doped NaI:Tl,6Li crystals serving as high-performance n-γ scintillators.

Two periods of magmatism in the Weishancheng ore concentration area, Henan Province: Evidences from zircon U‐Pb chronology, Hf isotopes and petrogeochemistry

The Weishancheng area of Tongbai County, Henan Province, is an important Au‐Ag polymetallic ore concentration area in China, characterized by a widespread distribution of plutons and frequent magmatic activities. To investigate the genetic relationship between magmatism and the mineralization of gold and silver polymetallic deposits in the area, this study focuses on the porphyritic monzogranite of the Liangwan pluton and the biotite granite of the Taoyuan pluton in detail. The zircon U‐Pb age of the Liangwan pluton is 128.5 ± 0.7 Ma, placing its intrusion age in the Early Cretaceous. Similarly, the zircon U‐Pb age of the Taoyuan pluton is 431.3 ± 2.7 Ma, indicating an intrusion age in the Early Silurian. Petrogeochemical analysis reveals that both the Liangwan and Taoyuan plutons exhibit high SiO2, Na2O and Al2O3 contents, along with low MgO, Fe2O3 and CaO contents, indicating a (high‐K) calc‐alkaline series, and have the properties of peraluminous I‐type granite. The total rare earth elements (REE) concentrations are low, with noticeable fractionation between light and heavy REE, and a negative Eu anomaly. High‐field‐strength elements (such as Nb, Ta, P, Ti) are depleted, while the large‐ion lithophile elements (such as Rb, K, Pb) are enriched. The εHf(t) values of the Liangwan and Taoyuan plutons range from −16.1 to −18.8 and from 11.0 to 14.6, respectively. The mean values of Hf two‐stage model ages (TDM2) are 603 Ma and 2230 Ma, respectively. These results suggest that the Liangwan pluton may have formed through partial melting of ancient crustal materials in the Palaeoproterozoic, during extensional tectonic events following the subduction of Izanagi Plate. It appears closely linked to Au‐Ag mineralization in the ore concentration area. The Taoyuan pluton likely originated from the depleted mantle and experienced some degree of crustal contamination. However, it is unrelated to regional mineralization.

Exploring Quantitative Biological Major, Trace, and Ultratrace Elements Composition and Qualitative Primary-Secondary Metabolites in Lamiaceae Medicinal Plants from Turkey.

Medicinal plants comprise a spectrum of constituents, encompassing both organic and inorganic elements. Elemental composition of 27 species of medicinal plants of Lamiaceae (including 17 endemic) family grown in Turkey was carried out by ICP-MS. The following elements were determined in analysed samples: Na, Mg, Al, K, Ca, Sc, Cr, Mn, Fe, Co, Zn, As, Rb, Sr, Cs, Ba, La, Ce, Sm, U, Se. Quantitative analysis of specific primary and secondary metabolites was carried out. Na and K are major constituents in plants. The concentrations of Na range from 332,495.590g/kg (in sample 10SA) to 279,690.674g/kg (in sample 4SA), while those of K vary from 67,492.456g/kg (in sample 15SA) to 3347.612g/kg (in sample 1A). Some metals such as Al, Cr, Mn, Fe, Co, Zn, As, Se, Rb, Sr, Cs, and Ba were also detected. Flavonoids, carbohydrates and tannins were present in all sample. Saponins were found in all samples except 1C and 2O. Coumarin were detected in samples 2N, 1T, 1O, 1Z, 3SA, 1C, 4SA, 6SA, 8SA, 1M, 11SA, 13SA, 2O, 14SA, 1H, and 16SI. Lipids were present in samples 6S, 9S, 1A, 10S, 1M, 11SA, 12SA, 13SA, 14SA, and 16SI. Plants contain essential, rare earth, and trace elements at mg/kg concentrations, while major elements such as K and Na are present in high levels. Toxic element As (arsenic) was detected in all analyzed plants, but in most samples, its concentration was below the threshold set by World Health Organization.

Provenance signature and tectono–sedimentary setting of the Permian Shihezi formation (Ordos basin, China): Insights from geochemistry and detrital zircon U–Pb dating

During the depositional period of the Permian Shihezi Formation, the southern margin of the Ordos Basin was a key location for studying the tectonic movement of the North China Craton (NCC) and South China Blocks. The sedimentary environment was the first period of complete transition from marine to continental. However, the distribution of sediments controlled by a multi–provenance supply and the response of deposition to tectonics remain ambiguous, and the restoration of paleogeography remains in the qualitative stage, restricting the study of larger-scale tectono–sedimentary patterns. Based on field profiles and core observations, the paleocurrent direction, lithic fragments, heavy mineral assemblages, rare earth element distribution patterns, 11 detrital zircon U–Pb age datasets, and discrimination diagram of major and trace elements, the provenance signature and tectono–sedimentary setting were revealed. The results indicated that there are three main provenances in the southern margin of the Ordos Basin: North Qilian and western and eastern sections of the North Qinling Orogenic Belt. The tectonic setting of the North Qilian was a continental island arc, and the North Qinling was transformed from a passive to an active continental margin. Owing to the continued intense tectonic activities of the North Qilian, a braided river delta with a large sedimentary range developed in the west, and it was mixed with detrital sediments from the western section of the North Qinling with weak tectonic activity in the central. Affected by the uplift of the southern North China Craton, the sedimentary environment in the eastern range was unstable, and the thickness distribution of sandy sediments in the braided river delta was uneven. Refinement of provenance and deposition has important implications for the study of basin–mountain coupling relationships and paleogeographic reconstruction in the southern Ordos Basin and provides a basis for the study of collision evolution of the North and South China Blocks in the Permian.

Gd and Ni co-doped BiFeO3 ferrite/r-GO nanocomposite for photocatalytic environmental remediation applications

Synergistic effects of the co-doping of rare earth and transition metals on the structural, electrical and optical, in multi-ferroic BiFeO3 nanoferrites (NFs) combined with reduced graphene oxide (r-GO) nanosheets, photocatalytic degradation properties can be boosted. In this current study gadolinium and nickel-co-doped Bi1-xGdxFe1-yNiyO3 were synthesised via the tartaric acid-assisted sol-gel method and their composite Bi1-xGdxFe1-yNiyO3/r-GO with 10 % reduced graphene oxide (r-GO) via the ultra-sonication route. Phase and structural investigation were carried out using x-ray diffraction (P-XRD), Raman scattering, and Fourier transform infrared (FTIR) analysis, which confirms the successful fabrication of co-doping in the rhombohedral geometry of the perovskite-type Bi1-xGdxFe1-yNiyO3. Electrical conductivity of the fabricated composite material was observed to increase because of the co-doping and the addition of r-GO. Photoluminescence (PL) spectra of co-doped and r-GO composite material exhibited a decline in PL intensity because optical bandgap energies exhibited narrowing of 1.99 eV and 1.91 eV respectively, which indicates the excellent separation and stabilization of photo-excited charge pairs. Special conduction properties of r-GO nanosheets improved electrical and optical properties, a well-porous nature, large surface area, lower bandgap, and increased dye degradation in the Bi1-xGdxFe1-yNiyO3/r-GO photocatalyst showing excellent photo-degradation of cationic malachite green (M.G.) dye, achieving a degradation efficiency of 96.4 % under natural solar light. Hence, the photocatalyst shows excellent stability where quenching of radicals using selective scavengers shows that OH* radicals and e−/h+ pairs are primarily involved in the mechanism of photo-degradation in a basic pH medium, making the as-fabricated material a potential material for photo-catalytic environmental remediation.

Mercury and rare earth elements (REEs) show different spatial trends in feathers of Kentish plover (Charadrius alexandrinus) breeding along the Adriatic Sea coast, Italy.

Feather analysis is an ethical and effective method for assessing the exposure of wild birds to environmental contamination due to trace elements and organic pollutants. We used feather to monitor the exposure to three toxic and non-essential metals (Hg, Cd, and Pb) and rare earth elements (REEs) of Kentish plover (Charadrius alexandrinus) breeding in different coastal areas (Veneto, Emilia-Romagna, Marche, Abruzzo, and Apulia) along the Italian coast of the Adriatic Sea. Feathers (n = 113) were collected from April to June. Feather concentrations evidenced a significant exposure to Hg (13.05 ± 1.71 mg kg−1 dw) and REEs (447.3 ± 52.8 ng g−1 dw) in the Kentish plover breeding in Veneto (n = 21) compared to the other coastal areas, with several individuals showing Hg concentrations above the adverse effect (5 mg kg−1 dw) and high-risk (9.14 mg kg−1 dw) thresholds reported for birds. Higher REE concentrations compared to Marche (n = 29), Abruzzo (n = 11) and Apulia (n = 13) were also reported for birds breeding in Emilia-Romagna (474.9 ± 41.9 ng g−1 dw; n = 29). The exposure to Cd and Pb was low in all the coastal areas, and only a few samples (n = 6 and n = 4 for Cd and Pb, respectively) exceeded the adverse effect thresholds (0.1 and 4 mg kg−1 for Cd and Pb, respectively). A significant sex-related difference was observed for REE-concentrations, with females showing higher concentration than males. These data highlight the need to monitor the exposure of the Kentish plover to Hg and REEs, especially in the northern basin of the Adriatic Sea, since these elements might negatively affect species' reproductive success and threaten its conservation.

Pre-concentration of REE values from nepheline syenite rocks of western Odisha, India

ABSTRACT The rare-earth elements (REEs) have gained enormous economic and scientific attention due to their distinct properties and new applications. Nepheline syenite rock is an important primary source of rare earth minerals. The nepheline syenite rocks from the Rairakhol area, western Odisha, have been characterized for their rare earth mineralogical and textural characteristics. Preliminary beneficiation studies of these rocks were carried out to upgrade the REE values using falcon gravity separation and floatation technique. Hornblende, biotite, K-feldspar, albite, and nepheline are the major mineral constituents of the nepheline syenite where REE-bearing minerals occur as accessory minerals. The REE mineral phases present are zircon, sphene, apatite, allanite, britholite, and REE phosphate, with grain sizes ranging from 10 to 50 microns. Allanite and britholite occupy the intergranular spaces of major mineral phases and occur as thin lines or veins whereas sphene and zircon occur as inclusions within major mineral phases. The flotation study shows that the total REE content of the froth product could be enriched to 1696 ppm, which is three times more than the total REE content (563 ppm) of the feed sample.