Criticality of the Rare Earth Elements

Recent constraints on supplies of the rare earth elements (REEs) have led to concerns about their long‐term availability as well as the consequences that shortages would pose for modern technology. To assess this situation, we apply a comprehensive “criticality” methodology to the REE: lanthanum (La); cerium (Ce); praseodymium (Pr); neodymium (Nd); samarium (Sm); europium (Eu); gadolinium (Gd); terbium (Tb); dysprosium (Dy); holmium (Ho); erbium (Er); thulium (Tm); ytterbium (Yb); lutetium (Lu); and yttrium (Y). Assessments are made on national (U.S. and China) and global levels for the year 2008. Evaluations of each indicator are presented and the results plotted in “criticality space” on a 0 to 100 scale. Over the medium term (5 to 10 years), supply risk (SR) for all REEs is moderate with minimal variation (62.8 to 65.1). Over the long term (10 to 100 years), SR is low (42.1 to 49.2). Environmental implications scores, reflecting the economic allocation of environmental burdens, range from 4.2 for La to 34.4 for Lu. Eu, Er, and Dy have the highest vulnerability to supply restriction (VSR) at the global level (50.6, 49.2, and 47.4, respectively), whereas Sm has the lowest (15.1). This is mainly a reflection of their substitution potential. Similarly, at the national level for the United States and China, Eu and Sm have the highest and lowest VSR scores, respectively, although there are notable differences in scores among the REEs and between countries. Although China's export restrictions render REE supplies inadequate to meet demand at present, our analysis indicates a lower criticality for REEs over the longer term than for a number of other industrially used metals.     

稀土元素生物效应中的Hormesis现象

综述了稀土元素在动物、植物和微生物生理、生化过程中的Hormesis现象,并就其机理进行了讨论,以期为进一步弄清稀土元素的生物效应机制提供参考。     

Recovery and Separation of Rare Earth Elements Using Salmon Milt

Recycling rare earth elements (REEs) used in advanced materials such as Nd magnets is important for the efficient use of REE resources when the supply of several REEs is limited. In this work, the feasibility of using salmon milt for REE recovery and separation was examined, along with the identification of the binding site of REEs in salmon milt. Results showed that (i) salmon milt has a sufficiently high affinity to adsorb REEs and (ii) the adsorption capacity of the milt is 1.04 mEq/g, which is comparable with that of commercial cation exchange resin. Heavier REEs have higher affinity for milt. A comparison of stability constants and adsorption patterns of REEs discussed in the literature suggests that the phosphate is responsible for the adsorption of REE in milt. The results were supported by dysprosium (Dy) and lutetium (Lu) L_III-edge extended x-ray absorption fine structure (EXAFS) spectroscopy. The REE-P shell was identified for the second neighboring atom, which shows the importance of the phosphate site as REE binding sites. The comparison of REE adsorption pattern and EXAFS results between the milt system and other adsorbent systems (cellulose phosphate, Ln-resin, bacteria, and DNA-filter hybrid) revealed that the coordination number of phosphate is correlated with the slope of the REE pattern. The separation column loaded with milt was tested to separate REE for the practical use of salmon milt for the recovery and separation of REE. However, water did not flow through the column possibly because of the hydrophobicity of the milt. Thus, sequential adsorption–desorption approach using a batch-type method was applied for the separation of REE. As an example of the practical applications of REE separation, Nd and Fe(III) were successfully separated from a synthetic solution of Nd magnet waste by a batch-type method using salmon milt.     

稀土多元复合肥和三种稀土元素的遗传毒性研究

采用蚕豆根尖细胞微核技术,研究市售稀土多元复合肥和稀土元素镧、铈、铒的化合物对蚕豆根尖细胞的遗传毒性和细胞毒性。结果表明,稀土复合肥和三种稀土元素均可诱发微核效应,在一定浓度下可损伤细胞,影响根尖的正常生长,其中稀土复合肥的微核效应表现出明显的剂量-效应关系。稀土复合肥和稀土元素镧、铈、铒的化合物对蚕豆根尖细胞具有一定的遗传毒性作用和细胞毒性作用,在施用稀土微肥和使用稀土制品时应引起重视。 Abstract：This paper presents the study of genetic toxicity and cell toxicity that is give n by rare earth multi-element compound fertilizer and a chemical compound of rar e earth elements-La3＋、Ce4＋、Er3＋ in root tip cells of Vicia faba.The technique used is micronucleus in root tip cells of Vicia faba.The experiment statistical result shows that both the rare earth compound fertilizer and the three kinds of rare earth elements can cause micronucleus ef fect and under certain concentration,they can hurt cells, affect root tip gro wth .The micronucleus effect of the rare earth compound fertilizer shows a clear relation of dosage-effect. The conclusion is that rare earth compound fertilize r and the chemical compound of rare earth elements La3＋、Ce4＋、E r3＋cause certain genetic toxicity and cell toxicity effect to root tip cells of Vicia faba.Therefore a close attention should be paid when the rar e earth multi-fertilizer and other things made by rare earth are used.     

Water quality response to the Angora Fire, Lake Tahoe, California

The Angora Fire (summer of 2007) was the largest and most severe wildfire in recent history within the Lake Tahoe basin of the Sierra Nevada. To determine the watershed response and to assess the potential for downstream impacts of nutrient and sediment delivery to Lake Tahoe, we monitored the post-fire hydrology and stream water chemistry for 2 years at four locations along the length of Angora Creek, a perennial stream draining the burned watershed. When compared with unburned streams, the hydrology of Angora Creek indicated an earlier and faster melting of the spring snowpack. Peak stream water concentrations of total N (TN) and ammonium occurred within the burned area, whereas peak concentrations of nitrate (NO₃ ^?), total P, soluble reactive P, total suspended solids, turbidity, electrical conductivity (EC), and dissolved organic C occurred below the burned area. In comparison to pre-fire data, TN, NO₃ ^?, TP, total dissolved P, EC, and turbidity increased following the fire, particularly in the wetter second year. Yields for subwatershed areas suggest that the burned urban subwatershed was the largest source of nutrients and sediments, whereas the wet meadow subwatershed downstream of the burned area retained materials. Erosion control efforts, below-average annual precipitation and the timing of its arrival (absence of summer and fall rainstorms), and the existence of a wet meadow below the burned watershed likely reduced the negative impacts that would have been expected from such a severe wildfire.     

稀土元素在药用植物细胞和组织培养中的应用

介绍了稀土元素对药用植物细胞、组织的生长及次生代谢产物合成的作用,探讨了稀土的作用机理。大量的实验证明,稀土在药用植物细胞和组织培养中具有广泛的应用前景。     

稀土元素在药用植物细胞和组织培养中的应用

介绍了稀土元素对药用植物细胞、组织的生长及次生代谢产物合成的作用,探讨了稀土的作用机理.大量的实验证明,稀土在药用植物细胞和组织培养中具有广泛的应用前景.     

稀土元素对短叶对齿藓生理生化的研究

通过测定分析3个主要生理指标过氧化物酶（POD）活性、丙二醛（MDA）含量和叶绿素含量的变化,研究了短叶对齿藓组培苗在6个不同浓度梯度的轻稀土La³⁺,Ce⁴⁺和重稀土Y³⁺单一元素胁迫下的生理响应和变化。结果如下：（1）短叶对齿藓体内的过氧化物酶（POD）活性和丙二醛（MDA）含量各处理组均低于对照组;Ce⁴⁺元素在3.55×10^-2 mmol·L^-1时显著提高了POD活性,在7.1×10^-2 mmol·L^-1时显著增加了膜脂过氧化产物丙二醛（MDA）含量。表明短叶对齿藓对Ce⁴⁺元素胁迫响应较强;而La³⁺元素各处理浓度间POD的变化较为平缓,胁迫响应较弱;Y³⁺处理居中。（2）较低浓度的La³⁺（1.8×10^-2 mmol·L^-1）和Ce⁴⁺（3.55×10^-2 mmol·L^-1）时显著提高叶绿素a、叶绿素b和总叶绿素含量;3种稀土元素在较高浓度时叶绿素的含量均有明显下降。本研究为进一步探明白云鄂博稀土矿区的苔藓植物生长发育受稀土元素的影响奠定了基础。     

Assessment the Exposure Level of Rare Earth Elements in Workers Producing Cerium,Lanthanum Oxide Ultrafine and Nanoparticles

In order to assess occupational exposure level of 15 rare earth elements (REEs) and identify the associated influence, we used inductively coupled plasma mass spectrometry (ICP-MS) based on closed-vessel microwave-assisted wet digestion procedure to determinate the concentration of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in urinary samples obtained from workers producing ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggest that La and Ce were the primary component, together accounting for 97 % of total REEs in workers. The urinary levels of La, and Ce among the workers (6.36, 15.32 μg.g^?1 creatinine, respectively) were significantly enriched compared to those levels measured in the control subjects (1.52, 4.04 μg.g^?1 creatinine, respectively) (p < 0.05). This study simultaneously identified the associated individual factors, the results indicate that the concentrations in over 5 years group (11.64 ± 10.93 for La, 27.83 ± 24.38 for Ce) were significantly elevated compared to 1–5 years group (2.58 ± 1.51 for La, 6.87 ± 3.90 for Ce) (p < 0.05). Compared the urinary levels of La and Ce at the separation and packaging locations (9.10 ± 9.51 for La, 22.29 ± 21.01 for Ce) with the other locations (2.85 ± 0.98 for La, 6.37 ± 2.12 for Ce), the results show urinary concentrations were significantly higher in workers at separation and packaging locations (p < 0.01). Inter-individual variation in levels of La and Ce in urine is the result of multi-factorial comprehensive action. Further researches should focus on the multiple factors contributing to the REEs levels of the occupationally exposed workers.     

Oxygen and Air Nanobubble Water Solution Promote the Growth of Plants,Fishes, and Mice

Nanobubbles (<200 nm in diameter) have several unique properties such as long lifetime in liquid owing to its negatively charged surface, and its high gas solubility into the liquid owing to its high internal pressure. They are used in variety of fields including diagnostic aids and drug delivery, while there are no reports assessing their effects on the growth of lives. Nanobubbles of air or oxygen gas were generated using a nanobubble aerator (BUVITAS; Ligaric Company Limited, Osaka, Japan). Brassica campestris were cultured hydroponically for 4 weeks within air-nanobubble water or within normal water. Sweetfish (for 3 weeks) and rainbow trout (for 6 weeks) were kept either within air-nanobubble water or within normal water. Finally, 5 week-old male DBA1/J mice were bred with normal free-chaw and free-drinking either of oxygen-nanobubble water or of normal water for 12 weeks. Oxygen-nanobubble significantly increased the dissolved oxygen concentration of water as well as concentration/size of nanobubbles which were relatively stable for 70 days. Air-nanobubble water significantly promoted the height (19.1 vs. 16.7 cm; P<0.05), length of leaves (24.4 vs. 22.4 cm; P<0.01), and aerial fresh weight (27.3 vs. 20.3 g; P<0.01) of Brassica campestris compared to normal water. Total weight of sweetfish increased from 3.0 to 6.4 kg in normal water, whereas it increased from 3.0 to 10.2 kg in air-nanobubble water. In addition, total weight of rainbow trout increased from 50.0 to 129.5 kg in normal water, whereas it increased from 50.0 to 148.0 kg in air-nanobubble water. Free oral intake of oxygen-nanobubble water significantly promoted the weight (23.5 vs. 21.8 g; P<0.01) and the length (17.0 vs. 16.1 cm; P<0.001) of mice compared to that of normal water. We have demonstrated for the first time that oxygen and air-nanobubble water may be potentially effective tools for the growth of lives.     

稀土元囊对小麦幼苗氮素吸收及同化的影响

稀土元素浸种能够促进小麦(Triticum aestivum L.)幼苗对No3-的吸收,提高硝酸还原酶活力。这些效应与稀土浓度有关,低浓度有促进作用,高浓度则有抑制作用。稀土元素处理还能促进小麦幼苗体内No3-的同化还原,使硝态氮含量降低,氨基氮含量增加,促进了氮素代谢过程。     

Investigation of Elements Sufficient To Imprint the Mouse Air Promoter

Imprinted maternal-allele-specific expression of the mouse insulin-like growth-factor type 2 receptor (Igf2r) gene depends on a 3.7-kb element named region 2, located in the second intron of the gene. Region 2 carries a maternal-allele-specific methylation imprint and contains an imprinted CpG island promoter (Air) that expresses a noncoding antisense RNA from the paternal inherited allele only. Here, we use transgenes to test the minimal requirements for imprinting of Air and to test if the action of region 2 is restricted to Igf2r. Transgenes up to 9 kb with Air as a single promoter are expressed but not imprinted. When coupled to the Igf2r CpG island promoter on a 44-kb transgene, Air was imprinted in one of three lines. However, Air on a 4.6-kb fragment is also imprinted in 2 of 14 lines when inserted in an intron of an adenine phosphoribosyltransferase (Aprt) transgene, and in one line, the imprinted methylation and expression of Air have been transferred onto the Aprt CpG island promoter. These data suggest that a dual CpG island promoter setting may facilitate Air imprinting as a short transgene and also show that Air can transfer imprinting onto other genes. However, for reliable Air imprinting, elements are necessary that are located outside a 44-kb region spanning the Air-Igf2r promoters.     

Uptake of Trace Metals and Rare Earth Elements from Hornblende by a Soil Bacterium

Analysis of trace elements released from hornblende between pH 6.5 and 7.5 in the presence of Arthrobacter sp. shows that Fe, Ni, V, Mn, and, to a lesser extent, Co are preferentially released into solution relative to bacteria-free experiments. This enhanced release into solution could be due to contributions from the slightly lowered pH, the presence of low molecular weight organic acids (LMWOAs), or the presence of a catecholate siderophore in experiments with bacteria. The best explanation for enhanced metal release is siderophore complexation at the mineral surface followed by release to solution. However,the relative rates of metal release to solution in these experiments do not strictly follow the trend predicted by the relative ordering of metal hydrolysis, which might be predicted for siderophore-promoted dissolution. For some of these metals, release to solution is fast initially in biotic experiments, but concentrations in solution reach a steady state value or decrease with time as the bacteria cell numbers increase exponentially. Lack of enhanced release to solution for some metals and decreases in release rate with time for others may be explained by uptake into bacteria. Many of the metals predicted to strongly complex with siderophore (including Al, Ti, Fe, Cu) are heavily taken up into cellular material. The relative ordering of organic ligand-element complexation may therefore partially explain the relative ordering of uptake of trace metals and rare earth elements into cell material. Fractionation of heavy rare earth elements taken up into cellular material is also very strong, and increases from Ho to Lu. Strong fractionation in uptake of some elements by bacteria may create biological signatures either in the mineral substrate or in any mineral precipitates associated with the cellular material.     

Undecaprenyl Pyrophosphate Involvement in Susceptibility of Bacillus subtilis to Rare Earth Elements

The rare earth element scandium has weak antibacterial potency. We identified a mutation responsible for a scandium-resistant phenotype in Bacillus subtilis. This mutation was found within the uppS gene, which encodes undecaprenyl pyrophosphate synthase, and designated uppS86 (for the Thr-to-Ile amino acid substitution at residue 86 of undecaprenyl pyrophosphate synthase). The uppS86 mutation also gave rise to increased resistance to bacitracin, which prevents cell wall synthesis by inhibiting the dephosphorylation of undecaprenyl pyrophosphate, in addition to enhanced amylase production. Conversely, overexpression of the wild-type uppS gene resulted in increased susceptibilities to both scandium and bacitracin. Moreover, the mutant lacking undecaprenyl pyrophosphate phosphatase (BcrC) showed increased susceptibility to all rare earth elements tested. These results suggest that the accumulation of undecaprenyl pyrophosphate renders cells more susceptible to rare earth elements. The availability of undecaprenyl pyrophosphate may be an important determinant for susceptibility to rare earth elements, such as scandium.     

稀土元素对酥梨叶片氮、磷、钾及其同化能力的影响

本文报道了稀土元素对酥梨叶片中氮、磷、钾含量,叶绿素含量及其光合效率的影响。结果表明,稀土元素有效地促进树体对氮、磷、钾的吸收。其中对磷的促进作用更显著。同时,增加了叶绿素含量,提高了光合强度。从而,提高了果实产量和品质。