Experimental evidence of the impact of rare-earth elements on particle growth and mechanical behaviour of silicon nitride

2006 ◽  
Vol 422 (1-2) ◽  
pp. 66-76 ◽  
Author(s):  
Raphaëlle L. Satet ◽  
Michael J. Hoffmann ◽  
Rowland M. Cannon
Keyword(s):  
Rare Earth ◽  
Silicon Nitride ◽  
Rare Earth Elements ◽  
Experimental Evidence ◽  
Mechanical Behaviour ◽  
Particle Growth ◽  
The Impact

scholarly journals Cretaceous-Paleogene boundary Fish Clay at Højerup (Stevns Klint, Denmark): Zn, Pb and REE in kerogen

2008 ◽  
Vol 73 (4) ◽  
pp. 453-461
Author(s):  
Pavle Premovic ◽  
Maja Stankovic ◽  
Mirjana Pavlovic ◽  
Milos Djordjevic
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Humic Substances ◽  
Rare Earths ◽  
Land Surface ◽  
Coastal Areas ◽  
Previous Hypothesis ◽  
Geochemical Analyses ◽  
The Impact ◽  
Fish Clay

Geochemical analyses of Zn, Pb and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in the kerogen of the black marl at the Cretaceous - Paleogene boundary Fish Clay at H?jerup were performed. Substantial proportions of the Zn, Pb and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics enriched in Zn, Pb and rare earth elements were transported mainly through fluvial transport into the deposition site of the Fish Clay. Local weathering/leaching of the impact-eject fallout on the land surface and local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing Zn, Pb and rare earths to these humic substances. Apparently, chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by exposed rocks in the coastal areas of eastern Denmark.

Experimental evidence for very low solubility of rare-earth elements in C02-rich fluids at mantle conditions

Nature ◽  
1989 ◽  
Vol 340 (6231) ◽  
pp. 301-303 ◽  
Author(s):  
James K. Meen ◽  
David H. Eggler ◽  
John C. Ayers
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Experimental Evidence ◽  
Low Solubility

Arrangement of rare-earth elements at prismatic grain boundaries in silicon nitride

2004 ◽  
Vol 84 (12) ◽  
pp. 755-762 ◽  
Author(s):  
G. B. Winkelman * ◽  
C. Dwyer ◽  
T. S. Hudson ◽  
D. Nguyen-Manh ◽  
M. Döblinger ◽  
...  
Keyword(s):  
Rare Earth ◽  
Silicon Nitride ◽  
Rare Earth Elements ◽  
Grain Boundaries

Green chemistry and sustainable development: approaches to chemical footprint analysis

2018 ◽  
Vol 90 (1) ◽  
pp. 143-155 ◽  
Author(s):  
Natalia P. Tarasova ◽  
Anna S. Makarova ◽  
Stanislav F. Vinokurov ◽  
Vladimir A. Kuznetsov ◽  
Pavel I. Shlyakhov
Keyword(s):  
Heavy Metals ◽  
Sustainable Development ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Regional Scale ◽  
Small Water ◽  
Federal Districts ◽  
Footprint Analysis ◽  
Development Goals ◽  
The Impact

AbstractThe methods to monitor the distribution of chemicals in the biosphere and to estimate the impact of chemicals on the biosphere are necessary to reach Sustainable Development Goals (SDGs). The paper presents the examples of methods to measure the concentration of heavy metals (including rare earth elements) and to rank them by the level of hazard to human health on different scales. The megacity scale presents the investigation of the impact of heavy metals on the small water bodies using water contamination index (WCI); and the investigation of snow contamination to estimate the level of short-term seasonal emission of heavy metals and rare earth elements. The 2nd part of the paper presents approaches to mitigate the exposure to mercury on the regional scale: the estimation of the current concentrations of mercury in atmospheric air, natural soils, and fresh waters using UNEP/SETAC USEtox model, as well as the estimations of the variations in the concentrations of mercury for the year 2045 in the federal districts of the Russian Federation, based on representative concentration pathways (RCPs) scenario and Minamata Convention scenario.

scholarly journals Increasing the depth of apatite processing by extracting rare-earth elements

2021 ◽  
Vol 266 ◽  
pp. 02002
Author(s):  
E.S. Lukyantseva ◽  
V.V. Sergeev
Keyword(s):  
Rare Earth ◽  
Phosphoric Acid ◽  
Rare Earth Elements ◽  
Extraction Process ◽  
Extractant Concentration ◽  
Wet Process ◽  
Heavy Rare Earth Elements ◽  
Knowledge Intensive ◽  
The Impact ◽  
Method Of Extraction

Currently, most high-technology productions are impossible without rare-earth elements (REE). The heavy rare-earth elements are of great interest as they have the highest market value and are in demand in the vast majority of knowledge-intensive industries. The main recourse of REE in Russia is apatite ore which is used in the production of fertilizers. As a result of its leaching, about 15-20% of REE goes to wet-process phosphoric acid. To enhance the depth of apatite processing, it is necessary to develop a technology which will allow obtaining rare-earth elements as by-products. The method of extraction and concentration of REE discussed in this paper was conducted by using the extractant based on di-(2-ethylhexyl) phosphoric acid (D2EHPA). The mechanism of extraction was studied, as well as the impact of the extractant concentration, phase ratio and the number of stages on the extraction process.

scholarly journals Some Mechanical Properties of Experimental Mg-Al -RE-Mn Magnesium Alloys

2014 ◽  
Vol 14 (1) ◽  
pp. 13-16 ◽  
Author(s):  
K.N. Braszczyńska-Malik
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Impact Strength ◽  
Rare Earth Elements ◽  
Mass Fraction ◽  
Brinell Hardness ◽  
Mechanical Tests ◽  
Gravity Casting ◽  
Compression Properties ◽  
The Impact

Abstract The results of some mechanical properties of four Mg-5Al-xRE-0.4Mn (x = 1 - 5) alloys are presented. The microstructure of experimental alloys consisted of an α-Mg phase and an α+γ semi-divorced eutectic, Al11RE3 phase and an Al10RE2Mn7 intermetallic compound. For gravity casting in metal mould alloys, Brinell hardness, impact strength, tensile and compression properties at ambient temperature were determined. The performed mechanical tests allowed the author to determine the proportional influence of the mass fraction of rare earth elements in the alloys on their tensile strength, yield strength, compression strength and Brinell hardness. The impact strength of the alloys slightly decreases with a rise in the rare earth elements mass fraction.

scholarly journals Effects of Lanthanum on the Photosystem II Energy Fluxes and Antioxidant System of Chlorella Vulgaris and Phaeodactylum Tricornutum

2019 ◽  
Vol 16 (12) ◽  
pp. 2242 ◽  
Author(s):  
Dong Sun ◽  
Ning He ◽  
Qi Chen ◽  
Shunshan Duan
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Antioxidant System ◽  
System Analysis ◽  
Marine Pollution ◽  
Kinetic Curve ◽  
Theoretical Data ◽  
Antioxidant Systems ◽  
Human Beings ◽  
The Impact

The rare earth elements are widely used in agricultural and light industry development. They promote the growth of crop seedlings, enhance root development and change the metal properties. Due to the large amount of rare earth minerals mined in China, rare earth elements have been detected in both coastal and estuary areas. They cause pollution and threaten the health of aquatic organisms and human beings. This study investigates the effects of lanthanum on two marine bait algae, and analyzes the changes in the photosynthetic and antioxidant systems of the two algae. The results show that rare earth elements have significant inhibitory effects upon the two algae. The OJIP kinetic curve value decreases with an increasing concentration of La(NO3)3 ·6H2O. The parameters of the fluorescence value were analyzed. The ABS/RC increases and the DI0/RC decreases during the first 24 h after exposure. The effects on the photosynthetic and antioxidant systems at low concentrations (both EC10 and EC20) show that the TR0/ABS increases, and the ET0/RC, ABS/RC, and DI0/RC has a decreasing trend after 30 min. However, after 24 h, normal levels were restored. In addition, the study finds that the TR0/ABS increases after 24 h, leading to an increase in reactive oxygen species. The antioxidant system analysis also confirms the increase in the activities of antioxidant enzymes, such as SOD and GSH. The experiment is expected to support the marine pollution of rare earths and the theoretical data of the impact on marine primary producers.

Cretaceous – Paleogene boundary Fish Clay at Højerup (Stevns Klint, Denmark): trace metals in kerogen

2007 ◽  
Vol 178 (5) ◽  
pp. 411-421 ◽  
Author(s):  
Pavle I. Premović ◽  
Bratislav Ž. Todorović ◽  
Mirjana S. Pavlović
Keyword(s):  
Rare Earth ◽  
Trace Metals ◽  
Rare Earth Elements ◽  
Humic Substances ◽  
Rare Earths ◽  
Land Surface ◽  
Coastal Areas ◽  
Geochemical Analyses ◽  
The Impact ◽  
Fish Clay

Abstract Geochemical analyses of trace metals (Ir, Ni, Co, Cr, Zn, Au and Pb) and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in kerogen of the black marl at the Cretaceous–Paleogene boundary Fish Clay at Højerup have been undertaken. Substantial proportions of the trace metals and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics were transported mainly through fluvial transport into the site of the deposition of the Fish Clay. The local weathering/leaching of the impact-ejecta fallout on the land surface or local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing trace metals and rare earths for these humic substances. Apparently, chondritic Ir, Au, Ni, Co, Cr and chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by the rocks exposed in the coastal areas of eastern Denmark.

scholarly journals How Do Rare Earth Elements (Lanthanoids) Affect Root Development and Protocorm-Like Body Formation in Hybrid CYMBIDIUM?

2014 ◽  
Vol 22 (1) ◽  
pp. 67-75
Author(s):  
Jaime A. Teixeira da Silva
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Negative Impact ◽  
Dry Weight ◽  
Nitrate Hexahydrate ◽  
Fresh Weight ◽  
Shoot Dry Weight ◽  
Plant Hybrid ◽  
The Impact

AbstractOnly few studies in the plant tissue culture literature have examined the impact of lanthanoids, or rare earth elements, on in vitro plant organogenesis. In this study, using a model plant, hybrid Cymbidium Twilight Moon ‘Day Light’, the impact of six lanthanoids (lanthanum (III) nitrate hexahydrate (La(NO3)3 · 6H2O), cerium (III) nitrate hexahydrate (Ce(NO3)3 · 6H2O), neodymium (III) nitrate hexahydrate (Nd(NO3)3 · 6H2O), praseodymium (III) nitrate hexahydrate (Pr(NO3)3 · 6H2O), samarium (III) nitrate hexahydrate (Sm(NO3)3 · 6H2O), gadolinium (III) nitrate hexahydrate (Gd(NO3)3 · 6H2O) on new protocorm-like body (neo-PLB) formation on Teixeira Cymbidium (TC) medium was examined. 0 (control), 1, 2, 4 and 8 mg·dm-3 of each lanthanoid was tested. All lanthanoids could produce more neo-PLBs and neo-PLB fresh weight than TC medium lacking plant growth regulators (PGRs), suggesting some PGR-like ability of lanthanoids, although PLB-related traits (percentage of half-PLBs forming neo-PLBs; number of neo-PLBs formed per half-PLB; fresh weight of half-PLB + neo-PLBs) was always significantly lower than TC medium containing PGRs. Except for Gd, all other lanthanoids had no negative impact on the number of new leaves from neo-PLB-derived shoots, but all lanthanoids showed a significantly lower plant height, shoot fresh weight and shoot dry weight and, in most cases, SPAD (chlorophyll content) value. In addition, using the same concentration of the six lanthanoids, the ability to fortify root formation of neo-PLB-derived plantlets was also assessed. Except for Sm, all other lanthanoids significantly increased the number of roots, root fresh and dry weight.

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