Sm Concentrations Research Articles

2,6-Dithiopurine, a nucleophilic scavenger, protects against mutagenesis in mouse skin treated in vivo with 2-(chloroethyl) ethyl sulfide, a mustard gas analog

Sulfur mustard [bis(2-chloroethyl)sulfide, SM] is a well-known DNA-damaging agent that has been used in chemical warfare since World War I, and is a weapon that could potentially be used in a terrorist attack on a civilian population. Dermal exposure to high concentrations of SM produces severe, long-lasting burns. Topical exposure to high concentrations of 2-(chloroethyl) ethyl sulfide (CEES), a monofunctional analog of SM, also produces severe skin lesions in mice. Utilizing a genetically engineered mouse strain, Big Blue, that allows measurement of mutation frequencies in mouse tissues, we now show that topical treatment with much lower concentrations of CEES induces significant dose- and time-dependent increases in mutation frequency in mouse skin; the mutagenic exposures produce minimal toxicity as determined by standard histopathology and immunohistochemical analysis for cytokeratin 6 and the DNA-damage induced phosphorylation of histone H2AX (γ-H2AX). We attempted to develop a therapeutic that would inhibit the CEES-induced increase in mutation frequency in the skin. We observe that multi-dose, topical treatment with 2,6-dithiopurine (DTP), a known chemical scavenger of CEES, beginning 1h post-exposure to CEES, completely abolishes the CEES-induced increase in mutation frequency. These findings suggest the possibility that DTP, previously shown to be non-toxic in mice, may be useful as a therapeutic agent in accidental or malicious human exposures to SM.

Visible light emission and energy transfer processes in Sm-doped nitride films

Even though the great interest in studying the near-infrared light emission due to Er3+ ions for telecommunication purposes, efficient visible radiation can be achieved from many different rare-earth (RE) ions. In fact, visible and/or near-infrared light emission takes place in RE-doped wide bandgap semiconductors following either photon or electron excitation, suggesting their technological potential in devices such as light-emitting diodes (LED's) and flat-panel displays, for example. Taking into consideration these aspects, the present contribution reports on the investigation of AlN, BeN, GeN, and SiN thin films doped with samarium. The samples were prepared by sputtering and as a result of the deposition method and conditions they present an amorphous structure and Sm concentrations in the low 0.5 at. %. After deposition, the samples were submitted to thermal annealing treatments and investigated by different spectroscopic techniques. A detailed examination of the experimental data allowed to identify optical transitions due to Sm3+ and Sm2+ ions as well as differences in their mechanisms of photon excitation and recombination. Moreover, it is shown that the Sm-related spectral features and emission intensity are susceptible, respectively, to the atomic environment the Sm3+/Sm2+ ions experience and to the presence of non-radiative recombination centers.

Analysis of Chrome Tanned Leather Shavings Using Neutron Activation Analysis

Chrome tanned leather shavings collected from the federal college of chemical and leather technology (CHELTECH) Zaria, Nigeria's tannery were analyzed using centre for energy research and training (CERT), Zaria Nigeria's miniature neutron source reactor (MNSR). The main aim of this work was to determine the concentration of chromium and other constituents of the shavings. Chromium is known for its human toxicity which includes skin irritation, lung cancer, as well as Kidney, liver and gastric damages. The disposal of this waste without treatment will constitute a serious impact on the environment. The result obtained indicates that Chromium is as much as 1%. The analyzed concentrations of As, Ba, Br, Co, Fe, La, Na, Sb, Sc, Sm and Zn in the sample are also presented. The results obtained were validated with the data obtained from the analysis of certified reference materials, IAEA-336 (Lichen) and IAEA 359 (Cabbage).

Bioindication of volatile elements emission by the Puyehue–Cordón Caulle (North Patagonia) volcanic event in 2011

The emission of volatile pollutants from the volcanic eruption of the Puyehue–Cordón Caulle complex (North Patagonia Andean Range) that started in June 4th, 2011, was investigated by bioindication means with the epyphytic fruticose lichen Usnea sp. The elemental composition of pooled samples made up with 10 lichen thalli were analysed by Instrumental Neutron Activation Analysis. Eleven sampling sites were selected within the impacted region at different distance from the volcanic source. Five sites were selected as they were already sampled in a previous study prior to the eruption. Two other new sampling sites were selected from outside the impacted zone to provide non-impacted baseline sites.The elements associated with the lichen incorporation of particulate matter (PM) of geological origin were identified by linear correlation with a geochemical tracer (Sm concentrations). The elements associated with PM uptake were Ce, Eu, Fe, Hf, La, Lu, Na, Nd, Sb, Sc, Se, Ta, Tb, Th, U, and Yb. Arsenic and Cs concentrations showed contributions exceeding the PM fraction in sites near the volcanic centre, also higher than the baseline concentrations, which could be associated with permanent emissions from the geothermal system of the Puyehue–Cordón Caulle complex. The lichen concentrations of Ba, Ca, Co, Hg, K, Rb, Sr, and Zn were not associated with the PM, not showing higher concentrations in the sites nearby the volcanic source or respect to the baseline values either. Therefore, there is no indication of the emission of volatile forms of these elements in the lichen records. The lichen records only identified Br volatile emissions associated with the Puyehue–Cordón Caulle complex eruption in 2011.

Microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu)5 thin films grown on Ru underlayer

In this paper, microstructure study of pinning sites of highly (0001) textured Sm(Co,Cu)5 thin films was presented. Various types of pinning sites were identified, such as voids, grain/matrix boundaries (or crystalline/amorphous boundaries), grain boundaries between crystalline grains, and composition inhomogeneity in grains. One key finding of TEM elemental mapping was that Cu atoms were rich in the inner part of Sm(Co,Cu)5 grains (defined by Sm and Co concentrations), instead of the outer part of grains, such as grain boundaries. Cu served as an alloying element in Sm(Co,Cu)5 grains, not as a doping element to form Cu-rich grain boundaries. A model of Sm(Co,Cu)5 films with lateral graded anisotropy due to composition/crystallization variation can explain the huge difference between the HC and HK.

Tillandsia usneoides L, a biomonitor in the determination of Ce, La and Sm by neutron activation analysis in an industrial corridor in Central Mexico

The atmosphere of the Tula Industrial Corridor in Central Mexico is contaminated due to several industries including oil refining while station monitoring in this area are limited. Lanthanides are considered fingerprint of oil refinery activities, and La, Ce and Sm have been previously detected in this area using filters. The suitability of T. usneoides as a biomonitor assessing the La, Ce and Sm concentrations in Particulate Matter is evaluated by NAA. Results of both biomonitor and filters are highly correlated.

A reddish La2O2S-based long-afterglow phosphor with effective absorption in the visible light region

Abstract Sm 3+ -activated La 2 O 2 S phosphors with good crystallinity were prepared by solid-state reaction. The formation mechanism of La 2 O 2 S formation was assumed and the phase change with different temperatures was discussed. The luminescence properties of phosphors with different sintering temperatures and different doping concentrations of Sm 3+ were investigated. The emission peak at 605 nm showed a well intensity can be attributed to the 4 G 5/2 → 6 H 7/2 transition of Sm 3+ . The optical absorption of La 2 O 2 S phosphors showed a stronger intensity in UV–vis region comparing with the Y 2 O 2 S phosphors. The long afterglow properties were investigated after the phosphors were excited with a fluorescent lamp. Phosphorescence lasted for about 3 min in the limit of light perception of the dark-adapted human eye (0.32 mcdm −2 ).

Concentration influence on temperature-dependent luminescence properties of samarium substituted strontium tetraborate

The series of divalent samarium substituted strontium tetraborate (Sr 1− x Sm x B 4O 7) polycrystalline samples were prepared by the conventional solid-state reaction. The phase formation of the samples was investigated by X-ray powder diffraction measurements. The luminescence spectra and decay curves of the Sm 2+ ions were measured. Temperature dependent Sm 2+ luminescence properties were investigated. The f–d and 5D 1– 7F J transitions appeared at 350 K and increased with increase in the temperature while the intensity of 5D 0– 7F J transitions decreased. The emission spectra pointed out that Sm 2+ occupies of C 2v or lower symmetry site. The photoluminescence decay times of strontium tetraborate doped with different concentrations of Sm 2+ was investigated as a function of temperature in the range of 100–500 K. However, no obvious concentration quenching was observed.

Ce3+ Ions Determine Redox-Dependent Anti-apoptotic Effect of Cerium Oxide Nanoparticles

Antioxidant therapy is the novel frontier to prevent and treat an impressive series of severe human diseases, and the search for adequate antioxidant drugs is fervent. Cerium oxide nanoparticles (nanoceria) are redox-active owing to the coexistence of Ce(3+) and Ce(4+) oxidation states and to the fact that Ce(3+) defects, and the compensating oxygen vacancies, are more abundant at the surface. Nanoceria particles exert outstanding antioxidant effects in vivo acting as well-tolerated anti-age and anti-inflammatory agents, potentially being innovative therapeutic tools. However, the biological antioxidant mechanisms are still unclear. Here, the analysis on two leukocyte cell lines undergoing apoptosis via redox-dependent or independent mechanisms revealed that the intracellular antioxidant effect is the direct cause of the anti-apoptotic and prosurvival effects of nanoceria. Doping with increasing concentrations of Sm(3+), which progressively decreased Ce(3+) without affecting oxygen vacancies, blunted these effects, demonstrating that Ce(3+)/Ce(4+) redox reactions are responsible for the outstanding biological properties of nanoceria.

Comparison of Trace Element Concentrations in Ambient Air of Industrial and Residential Areas in Tehran City

Tehran is densely populated possessing unhealthy and polluted air. There are 22 municipality districts in Tehran, and considerable numbers of industries are located within each district. Due to adverse environmental and health effects of trace elements in urban air, this study has been carried out to measure and compare concentration of trace elements including Ag, As, Br, Ce, Co, Cr, Cs, Cu, Mn, Hf, La, Sb, Sc, Sm, Th, and Zn in industrial (district 21) and residential (district 22) areas. For this purpose, total suspended particles were collected in two different time intervals in the year 2008. As a result, maximum and minimum concentrations in residential area associated with Mn (2.9μg/m(3)) and Hf (2.92 × 10(-4)μg/m(3)), respectively. Also, in industrial sites, these concentrations are higher for Mn (4.79 × 10(-1)μg/m(3)) and Hf (6.65 × 10(-4)μg/m(3)). The concentrations of Mn (2.07μg/m(3)) and Hf (7.46 × 10(-4)μg/m(3)) in traffic zone are close to residential values. General, concentrations of Ce, Co, Cs, La, Sc, Sm, Th, Br, and Hf in industrial area were higher than in residential area. The source of these elements in Tehran's air is mainly anthropogenic. According to the achieved results, the concentration levels of As, Cr, and Zn were close together in both residential and industrial zones. Therefore, these elements could have been originated from natural sources. Also, results show that levels of Ag, Mn, Sb, and Cu in residential area were higher than in industrial area. Finally, obtained data indicated that the trends of average concentration of trace elements in industrial area (from low to high) follow as Hf<Cs<Sm<Th<La<Ce<Sc<Co<Ag<As<Sb<Cr<Br<Zn<Cu<Mn and, in residential area, are in order of Hf<Cs<La<Th<Ce<Sc<Sm<Co<As<Ag<Br<Sb<Cr<Zn<Cu<Mn.

Plutonium uptake and behavior in vegetation of the desert southwest: A preliminary assessment

Eight species of desert vegetation and associated soils were collected from the Nevada National Security Site (N2S2) and analyzed for 238Pu and 239 + 240Pu concentrations. Amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. The diversity of growth strategies provided insight into the geochemical behavior and bio-availability of Pu at the N2S2. The highest concentrations of Pu were measured in the onion moss (24.27 Bq kg-1 238Pu and 52.78 Bq kg-1 239 + 240Pu) followed by the rimmed navel lichen (8.18 Bq kg-1 and 18.4 Bq kg-1 respectively), pointing to the importance of eolian transport of Pu. Brome and desert globemallow accumulated between 3 and 9 times higher concentrations of Pu than creosote and sage brush species. These results support the importance of species specific elemental accumulation strategies rather than exposure duration as the dominant variable influencing Pu concentrations in these plants. Total vegetation elemental concentrations of Ce, Fe, Al, Sm and others were also analyzed. Strong correlations were observed between Fe and Pu. This supports the conclusion that Pu was accumulated as a consequence of the active accumulation of Fe and other plant required nutrients. Cerium and Pu are considered to be chemical analogs. Strong correlations observed in plants support the conclusion that these elements displayed similar geochemical behavior in the environment as it related to the biochemical uptake process of vegetation. Soils were also sampled in association with vegetation samples. This allowed for the calculation of a concentration ratio (CR). The CR values for Pu in plants were highly influenced by the heterogeneity of Pu distribution among sites. Results from the naturally occurring elements of concern were more evenly distributed between sample sites. This allowed for the development of a pattern of plant species that accumulated Ce, Sm, Fe and Al. The highest accumulators of these elements were onion moss, lichen flowed by brome. The lowest accumulators were creosote bush and fourwing saltbush. This ranked order corresponds to plant accumulations of Pu.

Precise and accurate determination of Sm, Nd concentrations and Nd isotopic compositions in geological samples by MC-ICP-MS

In this work, we established a highly reproducible analysis of Sm, Nd concentrations and Nd isotopic compositions in geological samples by isotope dilution analysis with MC-ICP-MS. This technique is superior in terms of the analytical reproducibility or rapidity of analysis compared with quadrupole ICP-MS or with thermal ionization mass spectrometry (TIMS) isotope dilution techniques. Samples were spiked with 149Sm–150Nd enriched tracer and then digested by a commonly used HF, HNO3 and HClO4 acid protocol. The bulk rare earth elements (REEs) were separated from the sample on a standard cation exchange resin, and further purified on Eichrom Technologies Ln Resin, to obtain Sm and Nd fractions prior to mass spectrometric measurements. Replicate analyses of international certified reference materials (CRMs) demonstrate that our obtained 147Sm/144Nd and 143Nd/144Nd isotopic ratios are in good agreement with previously published values from isotope dilution methods. In addition to determining the concentrations of Sm and Nd, the Nd isotopic composition can be measured simultaneously during Nd isotope dilution run. Additionally, a mineral Sm-Nd isochronal age that is identical to, within error, a U-Th-Pb zircon age for the same rock is further measured and validates the robustness of the present protocol. Therefore, the high actual sample throughput inherent to the MC-ICP-MS can be fully exploited for the determination of Sm and Nd concentrations and Nd isotopic compositions.

Luminescence and X‐ray phosphor properties of samarium and lanthanum‐doped cubic barium chloride

AbstractLanthanum and samarium‐doped barium chloride samples with composition of the form Ba1‐x‐yLaxSmyCl2+x+y with x = 0.125 and 0 &lt; y &lt; 0.01 have been prepared in transparent ceramic form. X‐ray diffraction confirms that the material adopts the high temperature cubic (fluorite) phase of barium chloride. The photoluminescence spectrum shows a combination of broad band 5d and narrow 4f transitions. The broad band can be decomposed into strong and weak components which we attribute to Sm2+ ions with and without an adjacent interstitial Cl‐ ion respectively. The temperature dependence of the strongest broad band indicates that the lowest 5d level is 800 cm‐1 above the 5D0 level. The X‐ray induced fluorescence spectrum shows an additional blue emission band for Sm concentrations y &lt; 0.01 centred at around 420 nm which is ascribed to excitonic processes involving H centres. This emission band coincides with a photoluminescence excitation band for Sm2+ in this material, and so it is likely that the X‐ray induced luminescence from Sm2+ arises via an energy transfer process. Scintillation arising from the blue band can be observed, but is characterised by a long tail extending over hundreds of microseconds. The relative efficiency of the material as an X‐ray phosphor compared to commercial terbium‐doped gadolinium oxysulphide is around 11%. (© 2011 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

In situ U–Pb and Nd–Hf–(Sr) isotopic investigations of zirconolite and calzirtite

Although the calcium- and titanium-bearing zirconsilicates, zirconolite and calzirtite, are common minerals in carbonatites little is known regarding their trace element or isotopic characteristics. Available data indicate that they can have significant contents of U, Pb, Nb, Ta, Zr, Hf, rare earth elements (REEs), minor Sr and low Rb/Sr and Lu/Hf ratios. Their compositions indicate that they have potential for U–Pb age determination together with Nd–Hf and possibly Sr isotopic analyses. In this study, zirconolite and calzirtite from carbonatites occurring at Phalaborwa (South Africa), Prairie Lake (Canada), Afrikanda and Kovdor (Kola, Russia), Guli (Siberia, Russia) and Jacupiranga (Brazil) were selected for an isotopic analysis by in situ techniques. Ion microprobe analyses using a CAMECA 1280 ion microprobe show that reliable Pb–Pb ages can be obtained from these minerals as they have extremely high U concentrations, coupled with negligible common Pb. Although these minerals have low Rb/Sr ratios, their low Sr concentrations, in most cases, render in situ Sr isotopic analyses difficult. In contrast, their high Sm, Nd and Hf concentrations, with generally low Lu/Hf ratios, permit precise in situ isotopic analysis of Nd and Hf.

La, Ce, Pr, Nd and Sm concentrations in Pu'er tea of Yunnan, China

The rare earth elements contents (La, Ce, Pr, Nd, Sm) in 150 Pu'er tea samples were analyzed by using inductively coupled plasma atomic emission spectroscopy (ICP-AES), to evaluate the safety of Pu'er tea. Among the investigated rare earth elements (REEs), Ce was the highest (35% of the total REEs content) whose concentrations were found to be in the range of 0.11-1.39 mg/kg, whereas that of Sm in the range 0.01-0.21 mg/kg, showing minimum levels (5.2%). La was the second highest element (28%) found in Pu'er tea samples, followed by Nd (24%) and Pr (7.7%). The concentration of La was in the range of 0.07-1.14 mg/kg while that of Nd and Pr were in the range of 0.01-1.17 mg/kg and 0.01-0.30 mg/kg, respectively. The contents of La, Ce and Nd in ripened Pu'er tea were significantly higher than those in raw Pu'er tea. There were significant differences on the distribution of La, Ce, Pr, Nd and Sm in Pu'er tea among the main producing areas. Based upon the present Chinese quality safety standards, 43% samples in this study were found to be unsafe for human consumption.

Preparation and characterization of ZrO 2:Sm amorphous thin films by solid state photochemical deposition method

Thin films of ZrO 2 loaded with 10, 30 and 50 mol% Sm were prepared by a photochemical method using thin films of metal acetylacetonate complexes as precursors. The photolysis of these films induces the fragmentation of the acetylacetonate ligand and the partial reduction of metal ion together with volatile organic compounds. When the metallic complex is exposed to air, the product of the reaction is metal oxide. The photoreactivity of these films was monitored by FT-IR spectroscopy, followed by a post-annealing treatment process. The obtained films were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Photoluminescense studies of the films employed 400 nm radiation for excitation of the Sm ions present. The emission spectra showed signals arising from the 4G 5/2→ 6H J ( J=3/2, 7/2, 9/2) transitions, where the 4G 5/2→ 6H 3/2 transition has the highest intensity. The concentration dependence of the PL intensity was also studied. A maximum PL intensity was observed with 10 mol% Sm content but then diminished with higher Sm concentrations.

Calibration of Sm-Nd mixed spike by teflon powder method

Isotopic composition of Sm-Nd mixed spike was calibrated by teflon powder method. Sm and Nd isotopic compositions of the spike were externally calibrated with reference to the nNdǰstandard and normal Sm. Sm and Nd concentrations in the mixed spike were determined by isotope dilution protocol. Sm and Nd were separated by teflon powder method from the mixture of the spike with an interlaboratory standard (CIT Sm-Nd standard). We confirmed that precise Sm/Nd ratio (< 0.1 % error) and undisturbed Nd isotopic composition can be measured at the same time on condition that the sample to spike ratio is optimized. Garnet from the shear zone between the Gyeonggi massif and the Imjingang belt (Gyeonggi shear zone) was dated as a practical test of our experimental procedure. The Sm-Nd data of garnet, K-feldspar and whole rock samples from the shear zone define an Early Proterozoic age of 1730‚71 Ma, indicating that Sm-Nd system of the garnet was not disturbed during Triassic deformation.

ENHANCED PHOTOLUMINESCENCE OF Sm3+/Bi3+ CO-DOPED La2O3 NANOPHOSPHORS BY COMBUSTION SYNTHESIS

Nanosized La 2 O 3: Sm 3+ and La 2 O 3: Sm 3+, Bi 3+ phosphor powders were prepared via combustion synthesis. The structures and morphology were examined using powder X-ray diffraction and transmission electron microscope, respectively. The photoluminescence spectra were investigated at different doping concentrations of Sm 3+ and Bi 3+ ions. The results indicate that La 2 O 3: Sm 3+ ( Bi 3+) exhibited good crystallinity and spherical-like particles. All phosphors give emission bands centered at 564, 608 and 650 nm corresponding to 4 G 5/2→6 H J ( J =5/2, 7/2 and 9/2) transitions of Sm 3+ ions, respectively. Interestingly, the emission intensity of Sm 3+ ions is significantly enhanced with the addition of Bi 3+ ions to La 2 O 3: Sm 3+ and the maximum occurs at a Bi 3+ concentration of 0.8 mol%. The La 2 O 3: Sm 3+, Bi 3+ phosphor with highly enhanced luminescence is very encouraging for applications in display and tunable solid lasers.

Rare earth elements determination and distribution patterns in surface marine sediments of the South China Sea by INAA, Malaysia

Results obtained from the analysis of sediments surface samples taken from rivers mouth and polluted marine environment were analyzed for REE contents to determine the concentrations of La, Ce, Sm, Eu, Tb, Dy, Lu and Yb using instrumental neutron activation analysis. Thirty surface samples were collected from ten sites in the coastal marine sediments of the South China Sea along 957 km stretch of the east coast of Peninsular Malaysia. The samples prepared in the powdered form before irradiating them in a neutron flux of ~4 × 1012 n cm−2 s−1 at 750 kW power using the TRIGA Mark II research reactor at Malaysian Institute for Nuclear Technology (MINT). Results of the total concentration are used to establish baseline data in environmental pollution assessment and to develop the correlations between the Ce/Ce* anomalies and the distribution patterns of some the light rare earth elements (LREEs) and the heavy rare earth elements (HREEs). The Chondrite-normalized REE pattern from each site examined and used to explain the sedimentation patterns by anthropogenic activities and by natural processes such as shoreline erosion, weathering deposits. Shale-normalized (NASC) patterns suggest enrichment of LREEs relative to the HREEs with a positive Ce/Ce* anomaly. Validation of the used method was done using a Soil-7 SRM.

Study of the luminescent properties of KMgF 3:Sm

The photoluminescence (PL), radioluminescence (RL) and thermoluminescence (TL) of KMgF 3 doped at several Sm concentrations have been investigated. The maximum TL and RL yield under beta irradiation has been observed in KMgF 3:Sm 0.02 mol%. The glow curve of this doped perovskite is made up of at least five peaks located at 95, 120, 160, 270, and 330 °C. The third peak appears to be the most convenient for personal or environmental dosimetry, since it shows no fading and good linearity within the investigated dose range (0.020–200 Gy). From the RL and PL spectra it has been found that most of KMgF 3:Sm emission is located at wavelengths higher than 650 nm. This emission, which is characteristic of Sm 2 + , makes this doped compound attractive for fiber-optic dosimetry.