scholarly journals Effect of the Rare Earth Element Lanthanum (La) on the Growth and Development of Citrus Rootstock Seedlings

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1388
Author(s):  
Hang Yin ◽  
Junxiu Wang ◽  
Yao Zeng ◽  
Xinjian Shen ◽  
Yizhong He ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Growth And Development ◽  
Earth Element ◽  
Growth Parameters ◽  
Poncirus Trifoliata ◽  
Trifoliate Orange ◽  
Low Concentrations ◽  
Citrus Rootstock ◽  
Hormesis Effect

Rare earth elements (REEs) can affect the growth and development of plants. However, few studies have been carried out on the effects of REEs on citrus seedlings. In this study, the growth parameters, toxicity symptoms, chlorophyll content, and La content of three citrus rootstocks are analyzed under different concentrations of La, a representative REE. The results show that the growth of citrus rootstock seedlings was stimulated at La ≤ 0.5 mmol·L−1 and inhibited at concentrations above 1 mmol·L−1. The chlorophyll and carotenoid contents of trifoliate orange (Poncirus trifoliata L. Raf.) and Ziyang Xiangcheng (C. junos Sieb. ex Tanaka) leaves of plants grown at low concentrations of La (≤1.5 mmol·L−1) were similar to those of the control but were significantly reduced at 4 mmol·L−1 La. Toxic symptoms gradually appeared with increasing La concentrations, with yellowed leaves and burst veins appearing at 4 mmol·L−1 La. The symptoms of toxicity were most severe in trifoliate orange, followed by Shatian Pomelo (Citrus grandis var. shatinyu Hort) and then Ziyang Xiangcheng. Moreover, in leaves, the Ca content was significantly negatively correlated with La content (p < 0.01). These results indicate that La has a hormesis effect on the growth of citrus rootstocks. Of the studied citrus seedlings, Ziyang Xiangcheng is the most resistant to La.

scholarly journals Tracing method of Rare Earth Elements in surrounding rock of geological formation based on three-dimensional positioning algorithm

2021 ◽  
Vol 25 (1) ◽  
pp. 21-28
Author(s):  
Yan Lv ◽  
Laijun Lu ◽  
Mengxue Cao
Keyword(s):  
Mass Spectrometry ◽  
Rare Earth ◽  
Mass Spectrum ◽  
Rare Earth Elements ◽  
Earth Element ◽  
Three Dimensional ◽  
Test Sample ◽  
Surrounding Rock ◽  
Geological Formation ◽  
Positioning Algorithm

Because of the interference of mass spectrum and non-mass spectrum, the tracing accuracy of rare earth elements in the surrounding rock of geological formation is low. Pretreatment of test sample reagent, dissolution of test sample residue, characterization of rare earth element doped materials, analysis of mass spectrometry and non-mass spectrometry interference in rare earth element tracking, using three-dimensional positioning algorithm to track rare earth elements in geological strata surrounding rock. In the experiment, five samples of surrounding rock of geological strata are selected as experimental indexes. The experimental results show that the tracking accuracy of four rare earth elements is high.

scholarly journals Screening of ‘King’ Mandarin Hybrids as Tolerant Citrus Rootstocks to Flooding Stress

Horticulturae ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 388
Author(s):  
Mary-Rus Martínez-Cuenca ◽  
Amparo Primo-Capella ◽  
María Ángeles Forner-Giner
Keyword(s):  
Water Relations ◽  
Growth Parameters ◽  
Chlorophyll Concentration ◽  
Co2 Assimilation ◽  
Poncirus Trifoliata ◽  
Control Treatment ◽  
Gene Expressions ◽  
Flooding Stress ◽  
Citrus Rootstock ◽  
Osmotic Potentials

This work compares the tolerance to long-term anoxia conditions (35 days) of five new citrus ‘King’ mandarin (Citrus nobilis L. Lour) × Poncirus trifoliata ((L.) Raf.) hybrids (named 0501XX) and Carrizo citrange (CC, Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), the widely used citrus rootstock in Spain. Growth parameters, chlorophyll concentration, gas exchange and fluorescence parameters, water relations in leaves, abscisic acid (ABA) concentration, and PIP1 and PIP2 gene expressions were assessed. With a waterlogging treatment, the root system biomass of most hybrids went down, and the chlorophyll a and b concentrations substantially dropped. The net CO2 assimilation rates (An) and stomatal conductance (gs) lowered significantly due to flooding, and the transpiration rate (E) closely paralleled the changes in gs. The leaf water and osmotic potentials significantly increased in most 0501 hybrids. As a trend, flooding stress lowered the ABA concentration in roots from most hybrids, but increased in the leaves of CC, 05019 and 050110. Under the control treatment (Ct) conditions, most 0501 hybrids showed higher PIP1 and PIP2 expressions than the control rootstock CC, but were impaired due to the flooding conditions in 05019 and 050110. From this study, we conclude that 0501 genotypes develop some adaptive responses in plants against flooding stress such as (1) stomata closure to prevent water loss likely mediated by ABA levels, and (2) enhanced water and osmotic potentials and the downregulation of those genes regulating aquaporin channels to maintain water relations in plants. Although these traits seemed especially relevant in hybrids 050110 and 050125, further experiments must be done to determine their behavior under field conditions, particularly their influence on commercial varieties and their suitability as flooding-tolerant hybrids for replacing CC, one of the main genotypes that is widely used as a citrus rootstock in Spain, under these conditions.

The Obtaining Layered Composite Materials that Contain Rare Earth Element

2019 ◽  
Vol 822 ◽  
pp. 117-121
Author(s):  
A.N. Burlova ◽  
Fedor Y. Isupov ◽  
Sergey A. Kotov ◽  
Maria G. Livintsova
Keyword(s):  
Plastic Deformation ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Earth Element ◽  
Spent Nuclear Fuel ◽  
Layered Composite ◽  
Structural Elements ◽  
Friction Stir ◽  
Combination Of Methods ◽  
Metallurgical Processes

Materials with high content of rare-earth elements can be used for the manufacture of structural elements of containers for the transport of spent nuclear fuel. The combination of methods of powder metallurgy and methods of intensive plastic deformation allows to introduce a greater number of additives into the composition of the material than in the classical metallurgical processes. The article shows the possibility of using a combination of friction stir welding and friction stir processing in order to create a layered composite with a high content of rare-earth elements.

scholarly journals Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica

2020 ◽  
Vol 6 (41) ◽  
pp. eabb6570 ◽  
Author(s):  
Michael Anenburg ◽  
John A. Mavrogenes ◽  
Corinne Frigo ◽  
Frances Wall
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Element Mobility ◽  
Sodium Potassium ◽  
Ree Mineralization ◽  
Anionic Species ◽  
Ree Mobility ◽  
Modern Technologies

Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.

scholarly journals The Occurrence States of Rare Earth Elements Bearing Phosphorite Ores and Rare Earth Enrichment Through the Selective Reverse Flotation

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 698
Author(s):  
Wenxiang Chen ◽  
Feng Zhou ◽  
Hongquan Wang ◽  
Sen Zhou ◽  
Chunjie Yan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Ion Beam ◽  
Western China ◽  
Reverse Flotation ◽  
Flotation Process ◽  
Element Bearing ◽  
Element Contents

The reserve of rare-earth element-bearing phosphorite ores in Guizhou province in western China is huge. Increased demand for the different products manufactured from rare-earth elements has resulted in an extreme need for reasonable and comprehensive extraction of rare-earth elements. An improved understanding of rare-earth element occurrence states in single minerals of ores is important for their further processing. In this paper, rare-earth element contents were analyzed by inductively coupled plasma (ICP), and the occurrence states in single minerals were further investigated through SEM-EDS and focused ion beam-scanning electron microscope (FIB-SEM) methods. The results indicate that rare-earth element contents of apatite are far more than that of dolomite. No independent mineral of rare-earth elements exists for the studied sample. Rare-earth elements are present in the form of ions in the lattices of apatite. Based on the analysis of occurrence states and properties in single minerals, the distribution of rare-earth elements in the flotation process was investigated by reverse flotation technology. It shows that rare-earth elements are mainly concentrated in apatite concentrate. Under the optimized conditions, the P2O5 grade increases from 11.36% in the raw ore to 26.04% in the concentrate, and the recovery is 81.92%, while the total rare-earth oxide grade increases from 0.09% to 0.21% with the recovery of 80.01%, which is similar to P2O5 recovery. This study presents the feasibility of extracting rare-earth elements from rare-earth element-bearing phosphorite ores through the flotation of apatite.

Study on Mechanisms of Rare Earth Elements on Improving Thermoelectric Properties of RExCo4Sb12

2011 ◽  
Vol 71-78 ◽  
pp. 3737-3740
Author(s):  
Ke Gao Liu ◽  
Jing Li
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Mechanical Alloy ◽  
Spark Plasma Sintering ◽  
Thermoelectric Properties ◽  
Rare Earth Element ◽  
Figure Of Merit ◽  
Earth Element ◽  
Plasma Sintering ◽  
Spark Plasma

It is the important way to improve thermoelectric properties of skutterudite materials by doping with rare earth elements. The mechanisms of improving properties of bulk RExCo4Sb12materials prepared by mechanical alloy and spark plasma sintering (MA-SPS) at 650°C were investigated by analyzing the composition, microstructure and atomic occupying locations. According the results it can be considered that the mechanism to improve the thermoelectric properties of rare earth elements is that rare earth element Ce in the samples mainly plays the doping role in reducing the resistivity of the sample and improving the conductivity, so that it makes the figure of merit ZT of samples increase significantly.

Fractionation of rare-earth elements during magmatic differentiation and weathering of calc-alkaline granites in southern Myanmar

2016 ◽  
Vol 80 (1) ◽  
pp. 77-102 ◽  
Author(s):  
Kenzo Sanematsu ◽  
Terumi Ejima ◽  
Yoshiaki Kon ◽  
Takayuki Manaka ◽  
Khin Zaw ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Geochemical Characteristics ◽  
Magmatic Differentiation ◽  
Calc Alkaline ◽  
Mineral Assemblages ◽  
Weathering Resistance

AbstractGeochemical characteristics and rare-earth element (REE)-bearing minerals of calc-alkaline granites in southern Myanmar were investigated to identify the minerals controlling fractionation between light and heavyREE(LREE and HREE) during magmatic differentiation and weathering. The granites were classified on the basis of the mineral assemblages into two contrasting groups: allanite-(Ce)- and/or titanite-bearing granites; and more HREE-enriched granites characterized by hydrothermal minerals including synchysite(Y), parisite-(Ce), bastnäsite-(Ce), xenotime-(Y), monazite-(Ce), Y-Ca silicate, waimirite-(Y) and fluorite. This suggests that allanite-(Ce) and titanite are not stable in differentiated magma and HREE are eventually preferentially incorporated into the hydrothermal minerals. The occurrence of theREE-bearing minerals is constrained by the degree of magmatic differentiation and the boundary of two contrasting granite groups is indicated by SiO2contents of ∼74 wt.% or Rb/Sr ratios of ∼3–8. Fractionation between LREE and HREE during weathering of the granites is influenced by weathering resistance of theREE-bearing minerals, i.e. allanite-(Ce), titanite, theREEfluorocarbonates and waimirite-(Y) are probably more susceptible to weathering, whereas zircon, monazite-(Ce) and xenotime-(Y) are resistant to weathering. Ion-exchangeableREEin weathered granites tend to be depleted in HREE relative to the whole-rock compositions, suggesting that HREE are more strongly adsorbed on weathering products or that HREE remain in residual minerals.

Study on Recovery of Rare Earth Elements from NdFeB Magnet Scrap by Using Selective Leaching

2020 ◽  
Vol 1009 ◽  
pp. 149-154
Author(s):  
Tanongsak Yingnakorn ◽  
Piamsak Laokhen ◽  
Loeslakkhana Sriklang ◽  
Tapany Patcharawit ◽  
Sakhob Khumkoa
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Rare Earth Metals ◽  
Hard Disk Drives ◽  
Selective Leaching ◽  
High Concentration ◽  
Neodymium Magnets ◽  
The Rare Earth

High power neodymium magnets have been used extensively, such as components of hard disk drives, electric vehicles, and maglev trains. This type of magnet contains of high concentration of rare earth elements. After the device is out of service, the magnet will be removed and the rare earth element contained in the magnet will be extracted in order to reuse for any purposes. Recently, the study on extraction of rare earth elements (REE) from neodymium magnets is increased. However, there was only few research regarding to the extraction of rare earth metals by using a water leaching method. In this study, rare-earth elements were extracted from neodymium magnet scrap by using selective leaching technique. Initially, magnets were leached with 2 M of sulfuric acid for 24 hrs. Then, the leached solution was heated at 110°C in order to remove water and the green powder was remained. The green powder was further roasted in a muffle furnace at various temperatures from 750°C to 900°C for 2 hrs. and subsequently leached by water. Finally, the iron oxide residue was separated from rare earth element solution by filtration. Based on this experiment, it was found that the purity of the rare earth metals can be achieved up to 99.4%.

Origin, tectonic environment and age of the Bibole banded iron formations, northwestern Congo Craton, Cameroon: geochemical and geochronological constraints

2021 ◽  
pp. 1-19
Author(s):  
Arlette Pulcherie Djoukouo Soh ◽  
Sylvestre Ganno ◽  
Lianchang Zhang ◽  
Landry Soh Tamehe ◽  
Changle Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Atmospheric Oxygen ◽  
Banded Iron Formations ◽  
True Negative ◽  
Low Concentrations ◽  
Heavy Rare Earth Elements ◽  
Geochronological Constraints ◽  
Geochemical Studies ◽  
Iron Formations

Abstract The newly discovered Bibole banded iron formations are located within the Nyong Group at the northwest of the Congo Craton in Cameroon. The Bibole banded iron formations comprise oxide (quartz-magnetite) and mixed oxide-silicate (chlorite-magnetite) facies banded iron formations, which are interbedded with felsic gneiss, phyllite and quartz-chlorite schist. Geochemical studies of the quartz-magnetite banded iron formations and chlorite-magnetite banded iron formations reveal that they are composed of >95 wt % Fe2O3 plus SiO2 and have low concentrations of Al2O3, TiO2 and high field strength elements. This indicates that the Bibole banded iron formations were not significantly contaminated by detrital materials. Post-Archaean Australian Shale–normalized rare earth element and yttrium patterns are characterized by positive La and Y anomalies, a relative depletion of light rare earth elements compared to heavy rare earth elements and positive Eu anomalies (average of 1.86 and 1.15 for the quartz-magnetite banded iron formations and chlorite-magnetite banded iron formations, respectively), suggesting the influence of low-temperature hydrothermal fluids and seawater. The quartz-magnetite banded iron formations display true negative Ce anomalies, while the chlorite-magnetite banded iron formations lack Ce anomalies. Combined with their distinct Eu anomalies consistent with Algoma- and Superior-type banded iron formations, we suggest that the Bibole banded iron formations were deposited under oxic to suboxic conditions in an extensional basin. SIMS U–Pb data indicate that the Bibole banded iron formations were deposited at 2466 Ma and experienced metamorphism and metasomatism at 2078 Ma during the Eburnean/Trans-Amazonian orogeny. Overall, these findings suggest that the studied banded iron formations probably marked the onset of the rise of atmospheric oxygen, also known as the Great Oxidation Event in the Congo Craton.

Foliar application of rare earth elements to maize and mungbean

1999 ◽  
Vol 39 (2) ◽  
pp. 189 ◽  
Author(s):  
E. Diatloff ◽  
C. J. Asher ◽  
F. W. Smith
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Foliar Application ◽  
Dry Weight ◽  
Cerium Nitrate ◽  
Beneficial Effects ◽  
Shoot Dry Weight ◽  
The Rare Earth

The foliar application of rare earth elements to plants has been reported to increase yields of a range of crops particularly when soils contain low levels of rare earth elements. A rare earth element fertiliser obtained from China was chemically analysed and found to contain 45.3% nitrate plus 8.7% lanthanum and 12.4% cerium; lanthanum and cerium were the most abundant rare earth elements measured. This fertiliser was applied once, as 0, 0.025, 0.05, 0.1, 0.5 and 1.0% (w/v) aqueous solutions to the foliage of 10-day-old maize (Zea mays L. cv. Hycorn 82) and 14-day-old mungbean [Vigna radiata (L.) Wilczek cv. Berken] plants grown in a nutrient-rich potting mix of low total rare earth element status. For comparison, a duplicate set of plants was sprayed with solutions containing analytical grade lanthanum and cerium nitrate at concentrations equivalent to those measured in the rare earth element fertiliser. No beneficial effects of the rare earth element treatments were observed. The shoots of maize and mungbean sprayed with ≤0.1% rare earth element fertiliser or equivalent appeared completely healthy throughout the experiment, but plants in the 0.5 and 1.0% treatments showed symptoms of leaf burn in maize, and small necrotic spots on mungbean leaves within 1–3 days of treatment. These symptoms became more severe over the next 5–9 days. The shoot dry weight of mungbean sprayed with 0.5 and 1.0% solutions was significantly (P<0.05) reduced by 27%. Symptoms observed on plants sprayed with lanthanum and cerium nitrate solutions were similar to those observed on plants sprayed with the rare earth element fertiliser, and similar growth reductions occurred also.

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