Coupling Sr-Nd-Hf Isotope Ratios and Elemental Analysis to Accurately Quantify North African Dust Contributions to PM2.5 in a Complex Urban Atmosphere by Reducing Mineral Dust Collinearity

Tracking Saharan-Sahelian dust across the globe is essential to elucidate its effects on Earth's climate, radiation budget, hydrologic cycle, nutrient cycling, and also human health when it seasonally enters populated/industrialized regions of Africa, Europe, and North America. However, the elemental composition of mineral dust arising locally from construction activities and aeolian soil resuspension overlaps with African dust. Therefore, we derived a novel "isotope-resolved chemical mass balance" (IRCMB) method by employing radiogenic strontium, neodymium, and hafnium isotopes to accurately differentiate and quantitatively apportion collinear proximal and synoptic-scale crustal and anthropogenic mineral dust sources. IRCMB was applied to two air masses that transported African dust to Barbados and Texas to track particulate matter (PM) spikes at both locations. During Saharan-Sahelian intrusions, the radiogenic content of urban PM_2.5 increased with respect to ⁸⁷Sr/⁸⁶Sr and ¹⁷⁶Hf/¹⁷⁷Hf but decreased in terms of ¹⁴³Nd/¹⁴⁴Nd, demonstrating the ability of these isotopes to sensitively track African dust intrusions even in complex metropolitan atmospheres. The principal aerosol strontium, neodymium, and hafnium end members were concrete dust and soil, soil and motor vehicles, and motor vehicles and North African dust, respectively. IRCMB separated and quantified local soil and distal crustal dust even when PM_2.5 concentrations were low, opening a promising source apportionment avenue for urbanized/industrialized atmospheres.

Characterization of Neodymium Speciation in the Presence of Fulvic Acid by Ion Exchange Technique and Single Particle ICP-MS

It has been well known that the free ion concentration of metals plays a vital role in metal bioavailability. However, measurement of this fraction is still not easy over years of development. Nowadays, rare earth elements (REEs) are drawing more attentions as an emerging contaminant due to their wide applications in our daily life. To analyze the free ion concentration of neodymium (Nd), we adopted ion-exchange technique (IET) to investigate the changes on Nd free ion concentration in the presence of fulvic acid (FA). With the dynamic mode of IET analysis, the concentrations of Nd free ion were in the range of 0.85-36.8 × 10^-8 M at the total Nd concentration of 5 × 10^-7 M when FA varied from 0.4 to 10 M. However, these concentrations were 3-58 times higher than the one calculated by WHAM 7.0, which may be due to the particulate Nd spontaneously formed in solution. With single particle ICP-MS analysis, we found 0.25%-2.36% of Nd was in the form of colloids when the total Nd concentrations varied from 8.5 × 10^-9 to 4.7 × 10^-7 M, with the average particle sizes in the range of 26.5-39.2 nm. The presence of FA significantly decreased the number of Nd colloids, but increased the average particle size. Under the TEM, we found that Nd colloids were amorphous, with the size less than 200 nm. The present study provided a relatively new perspective on REE speciation in water. The natural organic matters not only affect the free ion concentration of Nd, but also influenced the size and numbers of Nd colloids in solution.

Rare earth elements in umbilical cord and risk for orofacial clefts

Questions remain about the effects of rare earth elements (REEs) on reproductive health, and no study has explored in utero exposure to REEs and risk of orofacial clefts (OFCs). We recruited subjects from a case-control study conducted in Shanxi Province, China. Concentrations of fifteen REEs were quantified in umbilical cord samples by means of Inductively Coupled Plasma Mass Spectrometry measurements. We employed logistic regression and weighted quantile sum (WQS) regression models to estimate the association between REEs exposures and OFCs. Of 226 subjects included in our study, 34 were cleft lip only, 44 were cleft lip with cleft palate and 6 were cleft palate only. In the logistic regression model, concentrations above the median of all subjects were associated with an increased OFCs risk of 2.35-fold (95% CI: 1.22, 4.53) for Lanthanum and 2.12-fold for Neodymium (95% CI: 1.10, 4.10) adjusting for maternal age, BMI, gestational weeks, sex of infants and passive smoking. In WQS model, a quartile increase in the index resulting in an increase of 3.10 (95% CI: 1.38, 6.96) in the odds of OFC. Lanthanum and Neodymium were suggested to be important factors. The results were largely consistent for OFC subtypes. In conclusion, in utero exposure to mixtures of REEs increased the risk of OFCs. Lanthanum and Neodymium were likely to be important factors in the development of OFCs.

La, Ce and Nd in the soil-plant system in a vegetation experiment with barley (Hordeum vulgare L.)

Rare earth elements (REEs) have received enormous attention in recent years. However, there are many gaps in the understanding of their behavior in the soil-plant system. The aim of this study is to investigate the behavior of three most common REEs (La, Ce, Nd) in the soil-plant system directly on soil samples using barley (Hordeum vulgare L.) in a vegetation experiment. We attribute the absence of significant changes in plant biomass and photosynthetic pigment content to the reduced availability of REEs in soil samples. The concentration of water-soluble forms of La, Ce and Nd didn't exceed 1 mg/kg, while the concentration of exchangeable forms varied and decreased in a row La > Ce > Nd. The transfer factor (TF) from soil to above-ground biomass was low for all three elements (<1). The stem-to-leaf TF increased with the increase in REEs concentration in soil. The concentration in plant material increased in the row Ce < Nd < La. REEs concentrations in barley leaves didn't exceed 1-3% of the corresponding element concentration in soil samples. REEs concentration in plant tissues is in close direct correlation with the REEs total concentration in soil, water-soluble and exchange forms. REEs concentration in barley leaves is 3-4 times higher than in the stems and for the group with extraneous concentration of 200 mg/kg for La, Ce and Nd was 6.20 ± 1.48, 2.10 ± 0.51, 6.90 ± 3.00 mg/kg, respectively. We show that there were no major changes in barley plants, but further study is needed of the relationship between the absorption of lanthanides by plants and the content of various forms of lanthanides in the soil.

Ecological Risk Assessment of Neodymium and Yttrium on Rare Earth Element Mine Sites in Ganzhou, China

Nowadays rare earth elements (REEs) are widely applied in high-technology and clean energy products, but their environmental risks are still largely unknown. To estimate the ecological risk of REEs, soil samples were collected from REE mine tailings with and without phytoremediation. The results showed that the tailings had rather low organic matter and high total REE concentrations, up to 808.5 mg/kg. The 10% effective concentration (EC10) of neodymium (Nd) and yttrium (Y) were calculated based on the toxicity tests of seed germination and root growth. For both wheat and mung bean, the EC10 of Nd and Y in soils were in the range of 1053.1-1300.1 mg/kg. The average hazard quotient of mine tailing soil without phytoremediation was higher than that with phytoremediation. All the hazard quotient of Nd and Y were less than 1, indicating that Nd or Y alone was unlikely to cause adverse ecological effects. Given to the coexistence of REEs on mine sites, the ecological risk of REE mixture could be potentially high towards local soil environments, even for soils with phytoremdiation.

Investigation of rare earth elements in urine and drinking water of children in mining area

To compare the contents of rare earth elements in urine and drinking water of children in the mining and control areas and evaluate the health risk of children in the mining area.Urine and drinking water of 128 children in the mining area and 125 children in the control area were collected from June to July 2015. The contents of rare earth elements were determined using inductively coupled plasma mass spectrometry.The detection rates of rare earth elements, including yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and samarium (Sm), in the urine of children in the exposed group were all 100%, except for samarium (98%); the rates in the control group were 85.7%, 100%, 100%, 98%, 98%, and 59.2%, respectively, and the remaining elements were not detectable. The concentrations of Y, La, Ce, Pr, Nd, and Sm in the urine of children in the exposed group were significantly higher than that in the control group (P < .01). In addition, the composition ratio of lanthanum was higher than that in the control group. The detection rates of lanthanum and Ce in the drinking water of children in the exposed group were 1.44% and 0.72%, respectively. The others were not detectable; the rates in the control group were all 0%.The pollution caused by the presence of Y, La, Ce, Pr, Nd, and Sm in the mining area might affect the health of children in the area, but drinking water might not be the cause.

Global patterns of dust and bedrock nutrient supply to montane ecosystems

A global compilation of erosion rates and modeled dust fluxes shows that dust inputs can be a large fraction of total soil inputs, particularly when erosion is slow and soil residence time is therefore long. These observations suggest that dust-derived nutrients can be vital to montane ecosystems, even when nutrient supply from bedrock is substantial. We tested this hypothesis using neodymium isotopes as a tracer of mineral phosphorus contributions to vegetation in the Sierra Nevada, California, where rates of erosion and dust deposition are both intermediate within the global compilation. Neodymium isotopes in pine needles, dust, and bedrock show that dust contributes most of the neodymium in vegetation at the site. Together, the global data sets and isotopic tracers confirm the ecological significance of dust in eroding mountain landscapes. This challenges conventional assumptions about dust-derived nutrients, expanding the plausible range of dust-reliant ecosystems to include many temperate montane regions, despite their relatively high rates of erosion and bedrock nutrient supply.

Dissolved rare earth elements in the central-western sector of the Ross Sea, Southern Ocean: Geochemical tracing of seawater masses

The present essay contributes to the existing literature on rare earth elements (REEs) in the southern hemisphere by presenting the first data, to our knowledge, on the vertical profiles of dissolved REEs in 71 samples collected in the central-western sector of the Ross Sea (Southern Ocean-SO). The REEs were measured in the water samples collected during the 2002-2003 and 2005-2006 austral summers. 4 samples were collected and analysed in the framework of a test experiment, as part of the WISSARD Project (Whillans Ice Stream Subglacial Access Research Drilling). Our results show significant differences between the REE patterns of the main water masses present in the SO: we could observe specific signature in the High Salinity Shelf Water (HSSW), Ice Shelf Water (ISW) and Low Salinity Shelf Water (LSSW). A significant increase in Terbium (Tb) concentration was observed in the HSSW and ISW, the two principal water masses contributing to the formation of Antarctic Bottom Water (AABW) in the Ross Sea area, and in LSSW. Some of the HSSW samples show enrichment in Neodymium (Nd). Dissolved REE could therefore be used as tracers to understand the deep circulation of the SO (Pacific sector). We hypothesize that: (I) the characteristic dissolved REE pattern may derive from the composition of source area and from the hydrothermal activity of the central-western area of the Ross Sea; (II) the Tb anomaly observed in the AABW on the South Australian platform could be partially explained by the contribution of AABW generated in the Ross Sea region.

Capillary electrophoresis coupled with in-column fiber-optic laser-induced fluorescence detection for the rapid separation of neodymium

In this study, in-column fiber-optic (ICFO) laser-induced fluorescence (LIF) detection technique is coupled with capillary electrophoresis (CE) for the rapid separation of neodymium for the first time. The effects of buffer concentration, buffer pH, and separation voltage on the CE behaviors, including electrophoretic efficiency and detection sensitivity, are investigated in detail. Under the optimal condition determined in this study (15 mM borate buffer, pH 10.50, separation voltage 24 kV), neodymium could be separated effectively from the neighboring lanthanides (praseodymium and samarium) within several minutes, and the limit of detection for neodymium is estimated to be at the ppt level. The ICFO-LIF-CE system assembled in this study exhibits unique performance characteristics such as low cost and flexibility. Meanwhile, the separation efficiency and detection sensitivity of the assembled CE system are comparable to or somewhat better than those obtained in the previous traditional CE systems, indicating the potential of the assembled CE system for practical applications in the fields of spent nuclear fuel analysis, nuclear waste disposal/treatment, and nuclear forensics.

Commercial-scale recycling of NdFeB-type magnets with grain boundary modification yields products with 'designer properties' that exceed those of starting materials

NdFeB-type magnets dominate the market for high performance magnetic materials, yet production of 'virgin' magnets via mining is environmentally, financially and energetically costly. Hence, interest is growing in 'magnet to magnet' recycling schemes that offer the potential for cheaper, more environmentally-friendly solutions to the world's growing appetite for rare-earth based magnetic materials. Unfortunately, previously described recycling processes only partially capitalise on this potential, because the methods described to date are limited to 'laboratory scale' or operate only under ideal conditions and result in products that fail to recapture the coercivity of the starting, scrap materials. Herein, we report a commercial scale process (120 kg batches) that completely recovers the properties of the starting scrap magnets. Indeed, 'grain boundary modification', via careful addition of a proprietary mix of blended elements, produces magnets with 'designer properties' that can exceed those of the starting materials and can be closely tailored to meet a wide variety of end-user applications, including high-coercivity (>2000 kA/m), sintered magnets suitable for motor applications.

Provenance tracing of Nd isotopes of sandstorm in Harbin, Heilongjiang province and analysis of its tracks

The present study analyzed sandstorms in Harbin, a city in Heilongjiang province in northeastern part of China. Based on the available ground observation data from meteorological stations in Harbin from 1961 to 2010, investigation was conducted for temporal and spatial distribution characteristics and weather conditions. 48 samples of dust collected from two sites were studied in laboratory. By testing the major and trace elements in samples collected, along with Nd isotope content, the component characteristics of these samples was determined. Annual change in law of sandstorm occurrence was found. Increase in occurrence of dust and sand was particularly obvious since 21st century. Occurrence of sandstorm frequency in different seasons was not same. It was high during spring and fall while low during summer and winter. Occurrence of sandstorm in Harbin was potentially related to direction of strong-wind, and winds from southwest was predominant; Horqin sandy land and Otindag sandy land was deemed as far-forth mass source, and the farmland and desertification area around Harbin was near-source.

Framework for resilience in material supply chains, with a case study from the 2010 Rare Earth Crisis

In 2010, Chinese export restrictions caused the price of the rare earth element neodymium to increase by a factor of 10, only to return to almost normal levels in the following months. This despite the fact that the restrictions were not lifted. The significant price peak shows that this material supply chain was only weakly resistant to a major supply disruption. However, the fact that prices rapidly returned to lower levels implies a certain resilience. With the help of a novel approach, based on resilience theory combined with a material flow analysis (MFA) based representation of the neodymium magnet (NdFeB) supply chain, we show that supply chain resilience is composed of various mechanisms, including (a) resistance, (b) rapidity, and (c) flexibility, that originate from different parts of the supply chain. We make recommendations to improve the capacity of the NdFeB system to deal with future disruptions and discuss potential generalities for the resilience of other material supply chains.

Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling

In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

Managing critical materials with a technology-specific stocks and flows model

The transition to low carbon infrastructure systems required to meet climate change mitigation targets will involve an unprecedented roll-out of technologies reliant upon materials not previously widespread in infrastructure. Many of these materials (including lithium and rare earth metals) are at risk of supply disruption. To ensure the future sustainability and resilience of infrastructure, circular economy policies must be crafted to manage these critical materials effectively. These policies can only be effective if supported by an understanding of the material demands of infrastructure transition and what reuse and recycling options are possible given the future availability of end-of-life stocks. This Article presents a novel, enhanced stocks and flows model for the dynamic assessment of material demands resulting from infrastructure transitions. By including a hierarchical, nested description of infrastructure technologies, their components, and the materials they contain, this model can be used to quantify the effectiveness of recovery at both a technology remanufacturing and reuse level and a material recycling level. The model's potential is demonstrated on a case study on the roll-out of electric vehicles in the UK forecast by UK Department of Energy and Climate Change scenarios. The results suggest policy action should be taken to ensure Li-ion battery recycling infrastructure is in place by 2025 and NdFeB motor magnets should be designed for reuse. This could result in a reduction in primary demand for lithium of 40% and neodymium of 70%.

Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum

This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

Atmospheric pollution in an urban environment by tree bark biomonitoring - part II: Sr, Nd and Pb isotopic tracing

The harmful effect of manmade particles on natural processes and human health is documented by a large number of studies showing a positive correlation between particulate matter (PM) concentration and health effects. Diminution of this health risk necessitates among others the precise knowledge of the particle sources, their physical and chemical properties and their dissemination in the environment. Pb isotope ratios have been successfully used during the past decades as tracers of anthropogenic Pb disseminated in the biosphere. Here we show that tree bark biomonitoring with lead (Pb), strontium (Sr) and neodymium (Nd) isotope ratios as tracers allow a thorough analysis of the impacts of industrial and other anthropogenic emissions on the urban environment. This is the first comprehensive multi-isotope tracer study of atmospheric pollution in an urban environment allowing to identify and to integrate the different plume paths of emissions in a digital map system. This innovative approach might become an important tool for environmental management and policy-making processes dealing especially with risks and surveillance of air quality in the urban environment.

Spectral and fluorescent kinetics features of Nd3+ ion in Nb2O5, Ta2O5 and La2O3 mixed lithium zirconium silicate glasses

Li(2)O-ZrO(2)-SiO(2):Nd(3+) glasses mixed with Nb(2)O(5), Ta(2)O(5) and La(2)O(3) were prepared. Optical absorption and photoluminescence spectra of these glasses have been recorded at room temperature. The Judd-Ofelt theory was successfully applied to characterize Nd(3+) spectra of all the three glasses. From this theory, various radiative properties like transition probability A, branching ratio β(r), the radiative lifetime τ(r), for (4)F(3/2) emission level in the spectra of these glasses has been evaluated. The radiative life time for (4)F(3/2) level of Nd(3+) ions has also been measured and quantum efficiencies were estimated. Among the three glasses studied, the La(2)O(3) mixed glass has exhibited the highest quantum efficiency. The reasons for such higher value have been discussed based on the relationship between the structural modifications taking place around the Nd(3+) ions.

Spontaneous and stimulated emission spectroscopy of a Nd(3+)-doped phosphate glass under wavelength selective pumping

The influence of the host matrix on the spectroscopic and laser properties of Nd(3+) in a K-Ba-Al phosphate glass has been investigated as a function of rare-earth concentration. Site-selective time resolved laser spectroscopy and stimulated emission experiments under selective wavelength laser pumping show the existence of a very complex crystal field site distribution of Nd(3+) ions in this glass. The peak of the broad stimulated (4)F(3/2)→(4)I(11/2) emission shifts in a non monotonous way up to 3 nm as a function of the excitation wavelength. This behavior can be explained by the relatively moderate inter-site energy transfer among Nd(3+) ions found in this system and measured by using fluorescence line narrowing spectroscopy. The best slope efficiency obtained for the laser emission was 40%.

Determination of the provenance of cocoa by soil protolith ages and assessment of anthropogenic lead contamination by pb/nd and lead isotope ratios

The Pb contents of chocolate and the products it flavors are among the highest of all commonly consumed substances. Others have shown that this Pb is acquired by cocoa beans after harvesting and is concentrated in their shells, portions of which are ground up with the cotyledons during processing. It is shown here that the shells also contain the lanthanides Nd and Sm, which they appear to take up more slowly than Pb when dried on bare soil. Consideration of Pb/Nd ratios, model Sm-Nd ages and the isotope ratios of Pb and Sr indicates that, in the absence of contamination, the relationship between Pb and Nd in shells is y = 13.1x(-0.383), where x is the Nd concentration in microg/kg and y is the Pb/Nd ratio. For cocoa powders, the relationship is y = 114x(-0.988). Samples that plot above these curves are probably contaminated. Model ages indicate where the cocoa of cocoa powders is grown, and these same considerations point to African samples being uncontaminated but samples from Asia containing 50% anthropogenic Pb of Australian origin. No measurable Pb contamination occurs during the transport of beans and the manufacture of chocolate.

Identifying the origins of local atmospheric deposition in the steel industry basin of Luxembourg using the chemical and isotopic composition of the lichen Xanthoria parietina

Trace metal atmospheric contamination was assessed in one of the oldest European industrial sites of steel production situated in the southern part of the Grand-Duchy of Luxembourg. Using elemental ratios as well as Pb, Sr, and Nd isotopic compositions as tracers, we found preliminary results concerning the trace metal enrichment and the chemical/isotopic signatures of the most important emission sources using the lichen Xanthoria parietina sampled at 15 sites along a SW-NE transect. The concentrations of these elements decreased with increasing distance from the historical and actual steel-work areas. The combination of the different tracers (major elements, Rare Earth Element ratios, Pb, Sr and Nd isotopes) enabled us to distinguish between three principal sources: the historical steel production (old tailings corresponding to blast-furnace residues), the present steel production (industrial sites with arc electric furnace units) and the regional background (baseline) components. Other anthropogenic sources including a waste incinerator and major roads had only weak impacts on lichen chemistry and isotopic ratios. The correlation between the Sr and Nd isotope ratios indicated that the Sr-Nd isotope systems represented useful tools to trace atmospheric emissions of factories using scrap metal for steel production.

Measurement of absolute intensities of some prompt γ-lines from the 91Zr, 143Nd, 177Hf and 116,118–120,122,124Sn(n,γ) reactions and isomeric cross-sections of 123m,125mSn by in-beam γ-spectroscopy method

The previously unknown absolute intensities of 28 prompt gamma-rays from the thermal neutron capture in 91Zr, 143Nd, 177Hf and 116,118-120,122,124Sn were measured by an in-beam gamma-spectroscopy method at the WWR-M reactor (PNPI, Gatchina). Cross sections of the production of isomers 123m,125mSn were also measured.

REE characteristics and Pb, Sr and Nd isotopic compositions of steel plant emissions

A comprehensive Pb-Sr-Nd isotope and REE tracer study of atmospheric trace metal pollution by a steel plant situated to the north of the urban communities of Strasbourg (France) and Kehl (Germany) has been performed using tree barks as biomonitors. The 206Pb/207Pb and 208Pb/207Pb isotopic ratios of the steel plant's filter dust are similar to values found in dust of waste incinerators. The 87Sr/86Sr ratio is similar to present-day ratios of Phanerozoic or Precambrian granitic rocks. The 143Nd/144Nd isotopic composition is very low and corresponds to an (Nd) value of -17.5. Such a low value is characteristic of old Precambrian granitic rocks and banded iron formations. Thus, this low (Nd) value might point to the origin of the iron necessary for the steel production. The fact, that this isotopic composition does not occur in crustal rocks of Western Central Europe makes the Nd isotope ratio a powerful tool to trace steel plants atmospheric emissions. The rare earth element (REE) distribution pattern of the steel plant's filter dust shows very specific fractionations like La and Nd enrichments which are traceable in tree barks over a distance of 4 km. The Pb, Sr and Nd isotope ratios not only enable the steel plant's emissions to be traced in a north-easterly direction, along the principal wind pathway but also enables the interference of this emission at 4 km NE from the steel plant with another atmospheric component originating from the Strasbourg Rhine harbour to be identified.

Vibrational spectra of mono, di and trimethyl ammonium double sulphates of rare earths Pr, Nd, Ho and Eu

Infrared and Raman spectra of four rare earth (Ho, Eu, Nd and Pr) double sulphates have been recorded and analysed based on the vibrations of methyl ammonium cations, sulphate anions and water molecules. Formation of hydrogen bonds of the type N-H...O and O-H...O are identified in all the compounds. Bifurcated hydrogen bonds are present in the compounds with dimethyl ammonium cations. The sulphate anions are distorted and occupy a lower site symmetry in the compounds. The bands obtained for (CH(3))(2)NH(2) and SO(4)(2-) ions indicate that the structural bonding of (CH(3))(2)NH(2)Eu(SO(4))(2).H(2)O and (CH(3))(2)NH(2)Ho(SO(4))(2).4H(2)O is identical. Electronic transition bands of Eu(3+) and Nd(3+) observed in the Raman spectra of these two compounds have been identified and discussed.

Dissolution of functional materials and rare earth oxides into pseudo alveolar fluid

The dissolution rates of rare earth oxides and two types of rare earth containing functional materials into water, saline solution, and Gamble's fluid were measured in order to evaluate the biological effects of rare earth-containing functional materials. The tested materials were yttrium, lanthanum, cerium and neodymium oxides, and neodymium-boron-iron magnet alloy (NdBFe) and lanthanum-mish-metal-nickel-cobalt (LmNiCo) hydrogen-containing alloy. The dissolution rates of the rare earth oxides were very low, resulting in concentrations of rare earth elements in the test solutions of the order of ppb. In the most extreme case, Gamble's fluid dissolved 1,400 times more of the rare earth oxides than pure water. Fairly high concentration of neodymium were found in the dissolving fluids, which means that trace neodymium present as an impurity in each rare earth oxide dissolved preferentially. For yttrium oxide, the ratio of neodymium to yttrium that dissolved in the saline solution was greater than 78,000 to 1, taking into account the amount of each that was originally present in the yttrium oxide.

Neodymium nanoparticles: biosynthesis and structural analysis

Small metallic nanoparticles of neodymium are obtained by a facile route based on the biosynthesis and the pH conditions that demonstrate the possibility of obtaining particles of 1-8 nm. The size is controlled by synthesis conditions. Smaller clusters were obtained with pH = 5, while for pH = 10 evidences of nanorods productions are found and this opens the perspective to use this rare-earth element for zero and one dimensional based applications. Using transmission electron microscopy techniques, the size distribution and structure are studied. Density functional theory-based calculations allow the determination of the lowest energy configuration, which is based on the hexagonal bulk symmetry. Theoretical models are used to simulate the high resolution transmission electron microscopy to identify the experimental image, determining that the synthesized nanoparticles reach the lowest energy hexagonal configurations.

Spectroscopic properties of neodymium(III)-containing polyoxometalates in aqueous solution

The spectroscopic properties of the neodymium(III)-containing polyoxometalates (POMs) [Nd(PW(11)O(39))(2)](11-), [Nd(PMo(2)W(9)O(39))(2)](11-), [Nd(PMo(4)W(7)O(39))(2)](11-), [Nd(PMo(6)W(5)O(39))(2)](11-), [Nd(SiMo(2)W(9)O(39))(2)](13-), [Nd(P(2)W(17)O(61))(2)](17-), [NdW(10)O(36)](9-), [NdP(5)W(30)O(110)](12-) and [NdAs(4)W(40)O(140)](25-) are described. Absorption spectra of aqueous solutions of the complexes have been recorded and the transition intensities are parameterised in terms of the Judd-Ofelt intensity parameters Omega(lambda) (lambda=2, 4, 6). Marked differences were found between the luminescence lifetimes of the complexes of the type Nd(POM) and those of the type Nd(POM)(2), due to a better shielding of the neodymium(III) ions from the bulk water molecules in the latter type of complexes.

[Determination of ten trace rare earth elements in the sample by atomic emission spectrometry]

This paper describes the determination of trace La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Yb and Lu in the sample, using carbon powder, potassium sulfate, barium sulfate, strontium sulfate, and scandium chloride as buffer, by atomic emission spectrometry (AES). Scandium was selected as internal standard line. Sample separation and chemical treatment were not required. The sample was directly loaded into ordinary electrode. The method is simple, rapid and accurate. The determination requirement and influence factors were studied. A new method was developed for the determination of ten rare earth elements, for which the detection limit is smaller than 0.030%, and the range of the recovery is 94%-105%. The results of these elements in standard sample are in agreement with certified values, and the RSD is smaller than 5% (n = 9). The method has been applied to the determination of ten rare earth elements with satisfactory results.

Neodymium neutron cross section measurements

Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m-long flight station with a 16-segment NaI(Tl) multiplicity detector, and the transmission measurements were performed at 15 and 25 m flight stations with a 6Li glass scintillation detector. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes lie within the energy range of 1.0-500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 0.5 b that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters.

Absolute isotopic composition and atomic weight of neodymium using thermal ionization mass spectrometry

Synthetic mixtures prepared gravimetrically from highly enriched isotopes of neodymium in the form of oxides of well-defined purity were used to calibrate a thermal ionization mass spectrometer. A new error analysis was applied to calculate the final uncertainty of the atomic weight value. Measurements on natural neodymium samples yielded an absolute isotopic composition of 27.153(19) atomic percent (at.%) 142Nd, 12.173(18) at.% 143Nd, 23.798(12) at.% 144Nd, 8.293(7) at.% 145Nd, 17.189(17) at.% 146Nd, 5.756(8) at.% 148Nd, and 5.638(9) at.% 150Nd, and the atomic weight of neodymium as 144.2415(13), with uncertainties given on the basis of 95% confidence limits. No isotopic fractionation was found in terrestrial neodymium materials.

Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol

A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.

Phosphorus as a potential guide in the search for extinct life on Mars

In contrast to the search for extant organisms, the quest for fossil remains of life on Mars need not be guided by the presence of water and organic compounds on the present surface. An appropriate tracer might be the element phosphorus which is a common constituent of living systems. Utilizing terrestrial analogues, it should preferentially exist in the form of sedimentary calcium phosphate (phosphorites), which would have readily resisted changing conditions on Mars. Moreover, higher ratios of P/Th in phosphorites in comparison to calcium phosphates from magmatic rocks give us the possibility to distinguish them from inorganically formed phosphorus deposits at or close to the Martian surface. Identification of anomalous phosphorus enrichments by remote sensing or in situ analysis could be promising approaches for selecting areas preferentially composed of rocks with remains of extinct life.

Rapid accretion and early differentiation of Mars indicated by 142Nd/144Nd in SNC meteorites

Small differences in the ratio of neodymium-142 to neodymium-144 in early formed mantle reservoirs in planetary bodies are the result of in situ decay of the extinct radionuclide samarium-146 and can be used to constrain early planetary differentiation and therefore the time scale of planetary accretion. The martian meteorite Nakhla (approximately 1.3 billion years old), the type sample of the nakhlite subgroup of the Shergottite-Nakhlite-Chassigny (SNC) meteorites, exhibits a 59 +/- 13 parts per million excess in the ratio of neodymium-142 to neodymium-144 relative to normal neodymium. This anomaly records differentiation in the martian mantle before 4539 million years ago and implies that Mars experienced no giant impacts at any time later than 27 million years after the origin of the solar system.