نتایج جستجو برای: REE elements

تعداد نتایج: 278802  

2018
Xiangmin Zhang Xiangfu Zeng Lianbin Liu Xiaolin Lan Jing Huang Hongxue Zeng Rong Li Keqing Luo Wei Wu Maohua Zhou Shaojin Li

The concentration and distribution of rare earth elements (REE) in nasopharyngeal carcinoma (NPC) were measured to investigate connections with tumor size, lymph node metastasis, clinical stages, and Epstein-Barr virus (EBV) infection. There were 30 patients with NPC who met the criteria for inclusion in the present study. The EBV copy number, as well as the concentration and distribution of RE...

Journal: :Environmental science. Processes & impacts 2017
Gwyneth Anne MacMillan John Chételat Joel P Heath Raymond Mickpegak Marc Amyot

Few ecotoxicological studies exist for rare earth elements (REEs), particularly field-based studies on their bioaccumulation and food web dynamics. REE mining has led to significant environmental impacts in several countries (China, Brazil, U.S.), yet little is known about the fate and transport of these contaminants of emerging concern. Northern ecosystems are potentially vulnerable to REE enr...

2011
Xiaoyue Du T. E. Graedel

The rare earth elements (REE) are a group of fifteen elements with unique properties that make them indispensable for a wide variety of emerging, critical technologies. Knowledge of the life cycles of REE remains sparse, despite the current heightened interest in their future availability. Mining is heavily concentrated in China, whose monopoly position and potential restriction of exports rend...

2001
Takuo Ozaki Shuichi Enomoto

Mechanisms of uptake of rare earth elements (REEs) were investigated, particularly those by REE accumulator species (autumn fern). Rare earth elements are practically insoluble under natural conditions, suggesting some unknown mechanism in REE accumulator species. In the present investigation, two notable phenomena were observed. (I) Concerning the ionic-radius dependence of REE uptake by leave...

Journal: :Journal of experimental botany 2005
Shiming Ding Tao Liang Chaosheng Zhang Juncai Yan Zili Zhang

Previous studies on rare earth element (REE) bioaccumulation have focused on their accumulation rate and fractionation, but the processes involved remain unclear. In this study, the accumulation and fractionation of REEs in wheat (Triticum aestivum L.) were investigated using solution culture with exogenous mixed REEs. A decrease in REE contents was observed from the roots to the tops of wheat....

2000
ILYA N. BINDEMAN ANDREW M. DAVIS

We present results from an ion microprobe study of REE-doped and natural concentration plagioclase-basalt run products of Drake (1972) that carries on from our earlier study (Bindeman et al., 1998). The goals of this work are (1) to determine plagioclase/melt partition coefficients for all REE for four analyzed plagioclase compositions (An40–80); and (2) to determine whether doping with REE inf...

2011

Definitions and characteristics The rare earth elements (REE) (sometimes referred to as the rare earth metals) are a group of 17 chemically similar metallic elements, including the 15 lanthanides, scandium and yttrium. The lanthanides are elements spanning atomic numbers 57 (lanthanum, La) to 71 (lutetium, Lu) (Table 1). The lanthanides all occur in nature, although promethium, the rarest, only...

2017
Cheng Xu Jindřich Kynický Martin P. Smith Antonin Kopriva Martin Brtnický Tomas Urubek Yueheng Yang Zheng Zhao Chen He Wenlei Song

Heavy rare earth elements (HREE) are dominantly mined from the weathering crusts of granites in South China. Although weathering processes occur globally, no economic HREE resources of this type have yet been found outside China. Here, we report the occurrence of unidentified REE minerals in the granites from South Chinese deposits. They contain high levels of both HREE and light REE, but are s...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2006
Yali Sun Min Sun Guochun Zhao

This study developed a methodology to analyze trace rare earth elements (REEs) in geological materials by capillary electrophoresis (CE). Changed from dilute HNO3 into a water medium by heating, REE ions are detectable at approximately 2 ng mL(-1). In the presence of coexisting elements from geological samples, REE separations were carried out. After sample fusion with Na2O2 and interference se...

2017
Marc Ulrich Sarah Bureau Catherine Chauvel Christian Picard

This study reports precise and accurate data for rare earth elements (REE) measured on eight geological reference materials, five enriched in REE (BE-N, BHVO-2, BR, BR-24 and RGM-1) and three very depleted in REE (BIR-1, UB-N and DTS-2). Data were acquired by quadrupole ICP-MS after isolation of the REE using an ion-exchange chromatography procedure. All the measured REE abundances are similar ...

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