Low-workfunction photocathodes based on acetylide compounds

DOEpatents

Terdik, Joseph Z; Spentzouris, Linda; Terry, Jr., Jeffrey H; Harkay, Katherine C; Nemeth, Karoly; Srajer, George

2014-05-20

A low-workfunction photocathode includes a photoemissive material employed as a coating on the photocathode. The photoemissive material includes A.sub.nMC.sub.2, where A is a first metal element, the first element is an alkali metal, an alkali-earth element or the element Al; n is an integer that is 0, 1, 2, 3 or 4; M is a second metal element, the second metal element is a transition metal or a metal stand-in; and C.sub.2 is the acetylide ion C.sub.2.sup.2-. The photoemissive material includes a crystalline structure or non-crystalline structure of rod-like or curvy 1-dimensional polymeric substructures with MC.sub.2 repeating units embedded in a matrix of A.

Linking the occurrence of cutaneous opportunistic fungal invaders with elemental concentrations in false killer whale (Pseudorca crassidens) skin.

PubMed

Mouton, Marnel; Przybylowicz, Wojciech; Mesjasz-Przybylowicz, Jolanta; Postma, Ferdinand; Thornton, Meredith; Archer, Edward; Botha, Alfred

2015-10-01

Cetaceans, occupying the top levels in marine food chains, are vulnerable to elevated levels of potentially toxic trace elements, such as aluminium (Al), mercury (Hg) and nickel (Ni). Negative effects associated with these toxic metals include infection by opportunistic microbial invaders. To corroborate the link between the presence of cutaneous fungal invaders and trace element levels, skin samples from 40 stranded false killer whales (FKWs) were analysed using culture techniques and inductively coupled plasma-mass spectroscopy. Twenty-two skin samples yielded 18 clinically relevant fungal species. While evidence for bioaccumulation of Hg in the skin of the FKWs was observed, a strong link was found to exist between the occurrence of opportunistic fungal invaders and higher Al : Se and Al : Zn ratios. This study provides indications that elevated levels of some toxic metals, such as Al, contribute to immunotoxicity rendering FKWs susceptible to colonization by cutaneous opportunistic fungal invaders. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Major and Trace Element Analysis of Natural and Experimental Igneous Systems using LA-ICP-MS

NASA Technical Reports Server (NTRS)

Jenner, Frances E.; Arevalo, Ricardo D., Jr.

2016-01-01

Major- and trace-element compositions of minerals provide valuable information on a variety of global Earth-system processes, including melting of distinct mantle reservoirs, the growth and evolution of the Earths crust and the formation of economically viable ore deposits. In the mid-1980s and early 1990s, attempts were made to couple laser ablation (LA) systems to inductively coupled plasma mass spectrometry (ICPMS) instruments (e.g. Fryer et al. 1995; Jackson et al. 1992). The goal was to develop a rapid, highly sensitive in situ analytical technique to measure abundances and spatial distributions of trace elements in minerals and other geological samples. Elemental analysis using LAICPMS was envisaged as a quicker and less destructive means of chemical analysis (requiring only g quantities) than labour-intensive sample digestion and solution analysis (requiring mg-levels of material); and it would be a more cost-effective method than secondary ion mass spectrometry (SIMS) for the routine analysis of trace elements from solid samples. Furthermore, it would have lower limits-of-detection than electron probe microanalysis (EPMA) (e.g. Jackson et al. 1992; Eggins 2003).

Toxic Elements in Different Medicinal Plants and the Impact on Human Health

PubMed Central

Brima, Eid I.

2017-01-01

Local medicinal plants from Madina, Saudi Arabia, are used to cure various diseases. However, some can cause adverse health effects. Five different medicinal plants were collected in the city of Madina: mahareeb (Cymbopogon), sheeh (Artemisia), harjal (Cynanchum argel delile), nabipoot (Equisetum), and kafmariam (Vitex agnus-castus). In total, four toxic elements including Al, Pb, As, and Cd were analyzed using inductively coupled plasma mass spectrometry (ICP-MS). The range of recoveries fell between 86.1 and 90.6% for all measured elements. Al levels were the highest of any of the studied elements in all plant samples, with Cymbopogon showing the highest levels. The range of concentrations of Al was 156–1609 mg/kg. Cd appeared at the lowest levels in all plants samples, with Vitex agnus-castus containing this element at the highest levels. Cd concentrations were in the range of 0.01–0.10 mg/kg. A washing process lowered the toxic elements in all plants; average % recoveries were Al (47.32%), As (59.1%), Cd (62.03%), and Pb (32.40%). The calculated human health risk assessment in one dose for toxic elements in all plants was as follows: Al (1.33 × 10−3–5.57 × 10−2 mg/kg.bw), Pb (0–8.86 × 10−5 mg/kg.bw), As (3.43 × 10−7–1.33 × 10−5 mg/kg.bw), and Cd (0–3.14 × 10−6 mg/kg.bw). Medicinal plants are a source of exposure to toxic elements. However, none of the plants in this study exceeded the daily guideline set by the WHO for any element based on conventional use by the local population. We may cautiously conclude that these medicinal plants pose no risk to users based on conventional use. PMID:29019913

Mechanical behaviour of pressed and sintered CP Ti and Ti-6Al-7Nb alloy obtained from master alloy addition powder.

PubMed

Bolzoni, L; Weissgaerber, T; Kieback, B; Ruiz-Navas, E M; Gordo, E

2013-04-01

The Ti-6Al-7Nb alloy was obtained using the blending elemental approach with a master alloy and elemental titanium powders. Both the elemental titanium and the Ti-6Al-7Nb powders were characterised using X-ray diffraction, differential thermal analysis and dilatometry. The powders were processed using the conventional powder metallurgy route that includes uniaxial pressing and sintering. The trend of the relative density with the sintering temperature and the microstructural evolution of the materials sintered at different temperatures were analysed using scanning electron microscopy and X-ray diffraction. A minimum sintering temperature of 1200°C has to be used to ensure the homogenisation of the alloying elements and to obtain a pore structure composed of spherical pores. The sintered samples achieve relative density values that are typical for powder metallurgy titanium and no intermetallic phases were detected. Mechanical properties comparable to those specified for wrought Ti-6Al-7Nb medical devices are normally obtained. Therefore, the produced materials are promising candidates for load bearing applications as implant materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

Determining baseline element composition of lichens. I. Parmelia sulcata at Theodore Roosevelt national park, North Dakota

USGS Publications Warehouse

Gough, L.P.; Severson, R.C.; Jackson, L.L.

1988-01-01

Element-concentration baselines are given for Parmelia sulcata and associated soils. Parmelia chlorochroa was found sporadically and therefore only representative concentration ranges are reported for this species. Element data include (1) for lichens; Al, As, Ba, B, Ca, Cr, Cu, Fe, Hg, Mn, Ni, P, Sr, S, Ti, V, Y, and Zn; and (2) for soils: Al, Ba, Be, Ca, Cs, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Nb, P, Pb, Sr, S, Ti, V, Y, and Zn. Very little (usually 7.2 km); thus, P sulcata is, in general, chemically similar throughout the park. This same uniformity was found for soil geochemistry. Numerous samples collected at close intervals would be required, therefore, to produce detailed element-concentration maps for P. sulcata and soils. No instances of elemental phytotoxic conditions were found; however, P. sulcata apparently possesses large concentrations of Ba, Cu, Fe, Pb, S, V, and possibly Zn.

NORTHROP REACTOR. REVISION NO. 1 TO THE FINAL SAFEGUARDS REPORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, J.M.; Shimizu, B.; Romine, R.A.

1962-10-01

Additions and changes related to the original application concerning construction and operation of the Northrop Reactor are given. Answers to 13 questions relative to the Final Safeguards Report are included. Answers are also included concerning 12 questions regarding receipt, possession, and storage of fuel elements. Other information is included concerning personnel changes and changes from Al-clad fuel elements to improved stainless steelclad hydride elements. It is concluded that the improved Northrop Reactor does not present any undue hazard to the health and safety of the operating personnel or the public. (J.R.D.)

First Principles Study of Adsorption of Hydrogen on Typical Alloying Elements and Inclusions in Molten 2219 Al Alloy.

PubMed

Liu, Yu; Huang, Yuanchun; Xiao, Zhengbing; Jia, Guangze

2017-07-19

To better understand the effect of the components of molten 2219 Al alloy on the hydrogen content dissolved in it, the H adsorption on various positions of alloying element clusters of Cu, Mn and Al, as well as the inclusion of Al₂O₃, MgO and Al₄C₃, were investigated by means of first principles calculation, and the thermodynamic stability of H adsorbed on each possible site was also studied on the basis of formation energy. Results show that the interaction between Al, MgO, Al₄C₃ and H atoms is mainly repulsive and energetically unfavorable; a favorable interaction between Cu, Mn, Al₂O₃ and H atoms was determined, with H being more likely to be adsorbed on the top of the third atomic layer of Cu(111), the second atomic layer of Mn(111), and the O atom in the third atomic layer of Al₂O₃, compared with other sites. It was found that alloying elements Cu and Mn and including Al₂O₃ may increase the hydrogen adsorption in the molten 2219 Al alloy with Al₂O₃ being the most sensitive component in this regard.

High Density Hydrogen Storage System Demonstration Using NaAlH4 Based Complex Compound Hydrides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel A. Mosher; Xia Tang; Ronald J. Brown

2007-07-27

This final report describes the motivations, activities and results of the hydrogen storage independent project "High Density Hydrogen Storage System Demonstration Using NaAlH4 Based Complex Compound Hydrides" performed by the United Technologies Research Center under the Department of Energy Hydrogen Program, contract # DE-FC36-02AL67610. The objectives of the project were to identify and address the key systems technologies associated with applying complex hydride materials, particularly ones which differ from those for conventional metal hydride based storage. This involved the design, fabrication and testing of two prototype systems based on the hydrogen storage material NaAlH4. Safety testing, catalysis studies, heat exchangermore » optimization, reaction kinetics modeling, thermochemical finite element analysis, powder densification development and material neutralization were elements included in the effort.« less

SiAlON ceramic compositions and methods of fabrication

DOEpatents

O'Brien, M.H.; Park, B.H.

1994-05-31

A method of fabricating a SiAlON ceramic body includes: (a) combining quantities of Si[sub 3]N[sub 4], Al[sub 2]O[sub 3] and CeO[sub 2] to produce a mixture; (b) forming the mixture into a desired body shape; (c) heating the body to a densification temperature of from about 1,550 C to about 1,850 C; (d) maintaining the body at the densification temperature for a period of time effective to densify the body; (e) cooling the densified body to a devitrification temperature of from about 1,200 C to about 1,400 C; and (f) maintaining the densified body at the devitrification temperature for a period of time effective to produce a [beta][prime]-SiAlON crystalline phase in the body having elemental or compound form Ce incorporated in the [beta][prime]-SiAlON crystalline phase. Further, a SiAlON ceramic body comprises: (a) an amorphous phase; and (b) a crystalline phase, the crystalline phase comprising [beta][prime]-SiAlON having lattice substituted elemental or compound form Ce.

Reconstructing Eolian Delivery to the Ulleung Basin (IODP Site U1430) Over the Past 12 Myr

NASA Astrophysics Data System (ADS)

Anderson, C. H.; Dunlea, A. G.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2017-12-01

Spring storms associated with the seasonal phases of the East Asian Monsoon (EAM), transport dust seaward and influence marine sedimentation in adjacent ocean regions. Here, we aim to track changes in the intensity of the EAM since the late Miocene by examining the relative proportions and sources of eolian inputs in marine sediment records. We use bulk sediment recovered from Site U1430 in the Ulleung Basin during Integrated Ocean Drilling Program Expedition 346 in 2013 to examine changes in the EAM over the past 12 Myr. Sediment recovered at this site is clayey silt, nannofossil and diatom oozes, claystone, and basal glauonitic sandstone. We analyze major, trace, and rare earth element concentrations for 72 bulk sediment samples analyzed by ICP-ES and ICP-MS, and interpret this dataset using a variety of multivariate statistical partitioning techniques (Q-mode Factor Analyses (QFA), Multiple Linear Regressions) to investigate sediment provenance. Sedimentologic observations and elemental concentrations indicate the presence of biogenic siliceous and carbonaceous components mixed with aluminosilicates. For example, Si/Al (g/g) reaches local maxima at 3 Ma and 10 Ma in several diatom rich sections, and Ca/Al (g/g) exhibits a peak at 0.58 Ma. Other downhole element ratios exhibit subtle variations, including Ti/Al of 0.05 +/- 0.004 g/g, Sc/Al 2 +/- 0.2 ug/g, and Rb/Al 17 +/- 1.5 ug/g. When plotted in ternary diagrams, samples exhibit offset arrays (La-Th-Sc) or multiple clusters (Zr-Nb-Sc) from an Upper Continental Crust and Mid-Ocean Ridge Basalt mixing line. In Th-Cr-Nb, the data exhibit a V-shaped array. The range of geochemical variability suggests that multiple sources of terrigenous matter and/or volcanic ash are being delivered to the site. The multivariate statistics also indicate the mixing of multiple aluminosilicate sources. Focusing on a suite of seven elements (Al, Ti, Sc, Cr, Rb, Th, La), preliminary QFA suggest that five factors are required to explain 99% of the variability in the dataset. Factors group different co-varying elements: Factor 1 Zr and Th, Factor 2 only Cr, Factor 3 Sc and La, Factor 4 Al and Sc, and Factor 5 with Rb and Th. Terrigenous inputs are likely from several sources including loess and other continental crustal material, and will be discussed further.

Diagnosis through rosary and sand: Islamic elements in the healing custom of the Yoruba (Nigeria).

PubMed

Sanni, Amidu

2002-01-01

The inhabitants of south western Nigeria are known as the Yoruba. Their earliest contact with Islam goes back to the 14th century, but it was only in the 19th century that the faith got firmly established, as Islamic mores and intellectual culture which included medical tradition - became well entrenched. Before the advent of Islam, diagnosis of ailments, witchcraft attacks etc., was carried out through a traditional procedure which involved the use of palm kernels, cowries, the latter similar to "bone throwing" among the Zulu of South Africa. This traditional system has since lost position to divination with rosary (subha) and sand (khatt al-raml), particularly among Muslims. This development notwithstanding, elements of the indigenous medical tradition medical tradition have been incorporated into the Islamic tradition. Inam Ahmad al-Buni (d.622.H) remains a point of reference among Yorouba Muslim healers and standard works on divination with sand, for example, Ahmad al-Afandi's (fl.1290 A.H.) ilm al-raml and al-Adhami's Mizan al-adl fi masqasis ahkam al-raml (1322.A.H.) continue to be popular. Nevertheless, the native Muslim diviners have developed their own literature for this and for divination with rosary, which betrays the level of their linguistic competence as well as the degree of acculturation and hybridization of indigenous and Islamic elements in a healing custom. This paper will examine how traditional elements had been grafted on Islamic divination, and how the practitioners continue to resolve the inherent contradictions between the two phenomena in their dual role as votaries of the Islamic faith and social workers in a medical tradition with a strong religious underpinning.

Influence of Alloying Elements on the Mechanical Properties of PtAl2 from First-Principles Calculations

NASA Astrophysics Data System (ADS)

Pan, Yong; Shi, Chang-Shuai

2018-04-01

Although PtAl2 is a promising high-temperature alloy, the improvement of its strength is still a big challenge. To solve this problem, we apply first-principles calculations to study the influence of alloying elements on the structural stability, elastic properties and brittle-or-ductile behavior of PtAl2. The results show that alloying elements prefer to occupy the Al site in comparison to the Pt site. Importantly, the calculated bulk modulus of doped PtAl2 is much larger than that of the parent PtAl2 due to the formation of TM-Pt and TM-Al bonds. In addition, alloying elements effectively improve the ductility of PtAl2. Finally, our work can provide new information to improve the mechanical properties of Pt-Al high-temperature materials.

Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Chen-Tung; Kandasamy, Selvaraj

2008-05-01

Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

Sialon ceramic compositions and methods of fabrication

DOEpatents

O'Brien, Michael H.; Park, Blair H.

1994-01-01

A method of fabricating a SiAlON ceramic body includes: a) combining quantities of Si.sub.3 N.sub.4, Al.sub.2 O.sub.3 and CeO.sub.2 to produce a mixture; b) forming the mixture into a desired body shape; c) heating the body to a densification temperature of from about 1550.degree. C. to about 1850.degree. C.; c) maintaining the body at the densification temperature for a period of time effective to densify the body; d) cooling the densified body to a devitrification temperature of from about 1200.degree. C. to about 1400.degree. C.; and e) maintaining the densified body at the devitrification temperature for a period of time effective to produce a .beta.'-SiAlON crystalline phase in the body having elemental or compound form Ce incorporated in the .beta.'-SiAlON crystalline phase. Further, a SiAlON ceramic body comprises: a) an amorphous phase; and b) a crystalline phase, the crystalline phase comprising .beta.'-SiAlON having lattice substituted elemental or compound form Ce.

Effect of Alloy Elements on Microstructures and Mechanical Properties in Al-Mg-Si Alloys

NASA Astrophysics Data System (ADS)

Kato, Yoshikazu; Hisayuki, Koji; Sakaguchi, Masashi; Higashi, Kenji

Microstructures and mechanical properties in the modified Al-Mg-Si alloys with variation in the alloy elements and their contents were investigated to enhance higher strength and ductility. Optimizing both the alloy element design and the industrial processes including heat-treatments and extrusion technology was carried out along the recent suggestion from the first principles calculation. The investigation concluded that the addition of Fe and/or Cu could recovery their lost ductility, furthermore increase their tensile strength up to 420 MPa at high elongation of 24 % after T6 condition for Al-0.8mass%Mg-1.0mass%Si-0.8mass%Cu-0.5mass%Fe alloy with excess Si content. The excellent combination between strength and ductility could be obtained by improvement to the grain boundary embitterment caused by grain boundary segregation of Si as a result from the interaction of Si with Cu or Fe with optimizing the amount of Cu and Fe contents.

Magnetite as the indicator of ore genesis for the Huangshaping polymetallic deposit, southern Hunan Province, China

NASA Astrophysics Data System (ADS)

Ding, T.; Ma, D.; Lu, J.; Zhang, R.

2017-12-01

Huangshaping polymetallic deposit, located in southern Hunan Province, China, hosts abundant W-Mo-Pb-Zn mineralization which linked with the skarn system located between late Mesozoic high-K calc-alkaline to shoshonitic granitoids and the Carboniferous carbonate in this deposit. In this study, concentrations of trace and minor elements of the magnetites from different skarn stages are obtained by in situ LA-ICP-MS analysis, in order to further understand the polymetallic mineralization processes within this deposit. The generally high concentrations of spinel elements, including Mg, Al, Ti, Mn, V, Cr, Co, Ni, Ga, Ge, and Sn, in all magnetites from this deposit suggest that these elements are incorporated into magnetite lattice by substituting Fe3+ and/or Fe2+. However, the various concentrations of Na, Si, K, Ca, and W elements in magnetites, combining the abnormal time-resolved analytical signals of LA-ICP-MS analyses, suggest that these elements are significantly affected by the fluid inclusions in magnetites. Two groups of magnetites can be further distinguished based on their trace and minor elements concentrations: Group-1 magnetites, including those in medium grain garnets and calcite, have obvious lower Na, Si, K, Ca, Sn, W, but higher Mg, Al, Ti, V, Co, Ni, Zn concentrations compared with Group-2 magnetites, which including those in coarse grain garnets, tremolite, and bulk magnetite ores. This suggests that the hydrothermal fluids where Group-2 magnetites precipitated are evolved magmatic fluids which have undergone the crystal fractionation during the early skarn stages (eg. Garnet and tremolite), the high Na, Si, K, and Ca in the hydrothermal fluids probably result from the dissolution of the host rocks, such as limestone, sandstone, and evaporite horizons in this deposit. However, the Group-1 magnetites probably precipitated in the hydrothermal fluids with low salinity, which result the low Na, Si, K, and Ca in these magnitites. Furthermore, these fluids might have undergone large scale circulation, the extraction from Zn-rich metamorphic basement and Mg, Al-rich strata probably have provided abundant Mg, Al, Zn in the hydrothermal fluids where Group-1 magnetites precipitated. As a conclusion, this study suggests that the compositions of magnetites can be the proxies of ore genesis.

The 1064 nm laser-induced breakdown spectroscopy (LIBS) inspection to detect the nutrient elements in freshly cut carrot samples

NASA Astrophysics Data System (ADS)

Yudasari, N.; Prasetyo, S.; Suliyanti, M. M.

2018-03-01

The laser-induced breakdown spectroscopy (LIBS) technique was applied to detect the nutrient elements contained in fresh carrot. Nd:YAG laser the wavelength of 1064 nm was employed in the experiments for ablation. Employing simple set-up of LIBS and preparing the sample with less step method, we are able to detect 18 chemical elements including some fundamental element of carrot, i.e Mg, Al, Fe, Mn, Ti, Ca, and Mn. By applying normalized profiles calculation on some of the element, we are able to compare the concentration level of each element of the outer and inner part of carrot.

Effect of Minor Alloying Elements on Localized Corrosion Behavior of Aluminum-Copper-Magnesium based Solid Solution Alloys

NASA Astrophysics Data System (ADS)

Aburada, Tomohiro

2011-12-01

The effects and mechanistic roles of a minor alloying element, Ni, on the localized corrosion behavior were explored by studying (Al75Cu 17Mg8)97Ni3 and Al70Cu 18Mg12 amorphous alloys. To explore the minor alloying element limited to the outer surface layers, the corrosion behavior of Al70Cu 18Mg12 amorphous alloy in solutions with and without Ni 2+ was also studied. Both Ni alloying and Ni2+ in solution improved the localized corrosion resistance of the alloys by ennobling the pitting and repassivation potentials. Pit growth by the selective dissolution of Al and Mg was also suppressed by Ni alloying. Remaining Cu and Ni reorganized into a Cu-rich polycrystalline nanoporous structure with continuous ligaments in pits. The minor Ni alloying and Ni2+ in solution suppressed the coarsening of the ligaments in the dealloyed nanoporous structure. The presence of relatively immobile Ni atoms at the surface suppressed the surface diffusion of Cu, which reduced the coarsening of the nanoporous structure, resulting in the formation of 10 to 30 nm wide Cu ligaments. Two mechanistic roles of minor alloying elements in the improvement of the pitting corrosion resistance of the solid solution alloys are elucidated. The first role is the suppression of active dissolution by altering the atomic structure. Ni in solid solution formed stronger bonds with Al, and reduces the probability of weaker Al-Al bonds. The second role is to hinder dissolution by producing a greater negative shift of the true interfacial potential at the dissolution front under the dealloyed layer due to the greater Ohmic resistance through the finer porous structure. These effects contributed to the elevation of pitting potentials by ennobling the applied potential required to produce enough dissolution for the stabilization of pits. Scientifically, this thesis advances the state of understanding of alloy dissolution, particularly the role of minor alloying elements on preferential oxidation at the atomic, nanometer, and micrometer scales. Technological implementations of the findings of the research are also discussed, including a new route to synthesize nanoporous materials with tunable porosity and new corrosion mitigation strategies for commercial Al-based alloys containing the detrimental Al2CuMg phase.

Compositions of HIMU, EM1, and EM2 from Global Trends between Radiogenic Isotopes and Major Elements in Ocean Island Basalts

NASA Astrophysics Data System (ADS)

Jackson, M. G.; Dasgupta, R.

2008-12-01

Sr and Pb isotopes exhibit global trends with the concentrations of major elements (SiO2, TiO2, FeO, Al2O3 and K2O) and major elements ratios (CaO/Al2O3 and K2O/TiO2) in the shield-stage lavas from 18 oceanic hotspots (including Hawaii, Iceland, Galapagos, Cook-Australs, St. Helena, Cape Verde, Cameroon, Canary, Madeira, Comoros, Azores, Samoa, Society, Marquesas, Mascarene, Kerguelen, Pitcairn, and Selvagen). Based on the relationships between major elements and isotopes in ocean island basalts (OIBs), we find that the lavas derived from the mantle end members, HIMU (or high 'ì' = 238U/204Pb), EM1 (enriched mantle 1), EM2 (enriched mantle 2), and DMM (depleted MORB [mid-ocean ridge basalt] mantle) exhibit distinct major element characteristics: When compared to oceanic hotspots globally, the hotspots with a HIMU (radiogenic Pb-isotopes and low 87Sr/86Sr) component, such as St. Helena and Cook-Australs, exhibit high CaO/Al2O3, FeOT, and TiO2 and low SiO2 and Al2O3. EM1 (enriched mantle 1; intermediate 87Sr/86Sr and low 206Pb/204Pb; sampled by hotspots like Pitcairn and Kerguelen) and EM2 (enriched mantle 2; high 87Sr/86Sr and intermediate 206Pb/204Pb; sampled by hotspots like Samoa and Societies) exhibit higher K2O concentrations and K2O/TiO2 weight ratios than HIMU lavas. EM1 lavas exhibit the lowest CaO/Al2O3 in the OIB dataset, and this sets EM1 apart from EM2. A plot of CaO/Al2O3 vs K2O/TiO2 perfectly resolves the four mantle end member lavas. Melting processes (pressure, temperature and degree of melting) fail to provide an explanation for the full spectrum of major element concentrations in OIBs. Such processes also fail to explain the correlations between major elements and radiogenic isotopes. Instead, a long, time integrated history of various parent- daughter elements appears to be coupled to major element and/or volatile heterogeneity in the mantle source. End member lava compositions are compared with experimental partial melt compositions to place constraints on the lithological characteristics of the mantle end members.

Compositions of HIMU, EM1, and EM2 from global trends between radiogenic isotopes and major elements in ocean island basalts

NASA Astrophysics Data System (ADS)

Jackson, Matthew G.; Dasgupta, Rajdeep

2008-11-01

Sr and Pb isotopes exhibit global trends with the concentrations of major elements (SiO 2, TiO 2, FeO, Al 2O 3 and K 2O) and major elements ratios (CaO/Al 2O 3 and K 2O/TiO 2) in the shield-stage lavas from 18 oceanic hotspots (including Hawaii, Iceland, Galapagos, Cook-Australs, St. Helena, Cape Verde, Cameroon, Canary, Madeira, Comoros, Azores, Samoa, Society, Marquesas, Mascarene, Kerguelen, Pitcairn, and Selvagen). Based on the relationships between major elements and isotopes in ocean island basalts (OIBs), we find that the lavas derived from the mantle end members, HIMU (or high 'μ' = 238U/ 204Pb), EM1 (enriched mantle 1), EM2 (enriched mantle 2), and DMM (depleted MORB [mid-ocean ridge basalt] mantle) exhibit distinct major element characteristics: When compared to oceanic hotspots globally, the hotspots with a HIMU (radiogenic Pb-isotopes and low 87Sr/ 86Sr) component, such as St. Helena and Cook-Australs, exhibit high CaO/Al 2O 3, FeO T, and TiO 2 and low SiO 2 and Al 2O 3. EM1 (enriched mantle 1; intermediate 87Sr/ 86Sr and low 206Pb/ 204Pb; sampled by hotspots like Pitcairn and Kerguelen) and EM2 (enriched mantle 2; high 87Sr/ 86Sr and intermediate 206Pb/ 204Pb; sampled by hotspots like Samoa and Societies) exhibit higher K 2O concentrations and K 2O/TiO 2 weight ratios than HIMU lavas. EM1 lavas exhibit the lowest CaO/Al 2O 3 in the OIB dataset, and this sets EM1 apart from EM2. A plot of CaO/Al 2O 3 vs K 2O/TiO 2 perfectly resolves the four mantle end member lavas. Melting processes (pressure, temperature and degree of melting) fail to provide an explanation for the full spectrum of major element concentrations in OIBs. Such processes also fail to explain the correlations between major elements and radiogenic isotopes. Instead, a long, time integrated history of various parent-daughter elements appears to be coupled to major element and/or volatile heterogeneity in the mantle source. End member lava compositions are compared with experimental partial melt compositions to place constraints on the lithological characteristics of the mantle end members.

Salton Sea 1/sup 0/ x 2/sup 0/ NTMS area California and Arizona: data report (abbreviated)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heffner, J.D.

1980-09-01

Surface sediment samples were collected at 997 sites. Ground water samples were collected at 76 sites. Neutron activation analysis results are given for uranium and 16 other elements in sediments, and for uranium and 9 other elements in ground water. Mass spectrometry results are given for helium in ground water. Data from ground water sites include (1) water chemistry measurements (pH, conductivity, and alkalinity) (2) physical measurements (water temperature, well description where applicable, and scintillometer reading) and (3) elemental analyses (U, Al, Br, Cl, Dy, F, He, Mg, Mn, Na and V). Data from sediment sites include (1) stream watermore » chemistry measurements from sites where water was available and (2) elemental analyses (U, Th, Hf, Al, Ce, Dy, Eu, Fe, La, Lu, Mn, Sc, Sm, Na, Ti, V, and Yb). Sample site descriptors are given. Areal distribution maps, histograms, and cumulative frequency plots for the elements listed above; U/Th and U/Hf ratios; and scintillometer readings at sediment sample sites are included. Analyses of the sediment fraction finer than 149..mu..m show high uranium values clustered in the Eagle and Chuckwalla Mountains. High uranium values in the 420 ..mu..m to 1000 ..mu..m fraction are clustered in the McCoy Mountains. Both fractions show groups of high values in the Chocolate Mountains at the Southeastern edge of the Chocolate Mountains Aerial Gunnery Range. Aerial distribution of analytical values shows that high values of many elements in both size fractions are grouped around the Eagle Mountains and the Chuckwalla Mountains. Fe, Mn, Ti, V, Sc, Hf, and the rare earth elements, all of which typically occur in high-density minerals, have higher average (log mean) concentrations in the finer fraction than in the coarser fraction.« less

Dart model for irradiation-induced swelling of dispersion fuel elements including aluminum-fuel interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rest, J.; Hofman, G.L.

1997-06-01

The Dispersion Analysis Research Tool (DART) contains models for fission-gas induced fuel swelling, interaction of fuel with the matrix aluminum, resultant reaction-product swelling, and calculation of the stress gradient within the fuel particle. The effects of an aluminide shell on fuel particle swelling are evaluated. Validation of the model is demonstrated by a comparison of DART calculations of fuel swelling of U{sub 3}SiAl-Al and U{sub 3}Si{sub 2}-Al for various dispersion fuel element designs with the data. DART results are compared with data for fuel swelling Of U{sub 3}SiAl-Al in plate, tube, and rod configurations as a function of fission density.more » Plate and tube calculations were performed at a constant fuel temperature of 373 K and 518 K, respectively. An irradiation temperature of 518 K results in a calculated aluminide layer thickness for the Russian tube that is in the center of the measured range (16 {mu}m). Rod calculations were performed with a temperature gradient across the rod characterized by surface and central temperatures of 373 K and 423 K, respectively. The effective yield stress of irradiated Al matrix material and the aluminide was determined by comparing the results of DART calculations with postirradiation immersion volume measurement of U{sub 3}SiAl plates. The values for the effective yield stress were used in all subsequent simulations. The lower calculated fuel swelling in the rod-type element is due to an assumed biaxial stress state. Fuel swelling in plates results in plate thickness increase only. Likewise, in tubes, only the wall thickness increases. Irradiation experiments have shown that plate-type dispersion fuel elements can develop blisters or pillows at high U-235 burnup when fuel compounds exhibiting breakaway swelling are used at moderate to high fuel volume fractions. DART-calculated interaction layer thickness and fuel swelling follows the trends of the observations. 3 refs., 2 figs.« less

Clinopyroxene-melt element partitioning during interaction between trachybasaltic magma and siliceous crust: Clues from quartzite enclaves at Mt. Etna volcano

NASA Astrophysics Data System (ADS)

Mollo, S.; Blundy, J. D.; Giacomoni, P.; Nazzari, M.; Scarlato, P.; Coltorti, M.; Langone, A.; Andronico, D.

2017-07-01

A peculiar characteristic of the paroxysmal sequence that occurred on March 16, 2013 at the New South East Crater of Mt. Etna volcano (eastern Sicily, Italy) was the eruption of siliceous crustal xenoliths representative of the sedimentary basement beneath the volcanic edifice. These xenoliths are quartzites that occur as subspherical bombs enclosed in a thin trachybasaltic lava envelope. At the quartzite-magma interface a reaction corona develops due to the interaction between the Etnean trachybasaltic magma and the partially melted quartzite. Three distinct domains are observed: (i) the trachybasaltic lava itself (Zone 1), including Al-rich clinopyroxene phenocrysts dispersed in a matrix glass, (ii) the hybrid melt (Zone 2), developing at the quartzite-magma interface and feeding the growth of newly-formed Al-poor clinopyroxenes, and (iii) the partially melted quartzite (Zone 3), producing abundant siliceous melt. These features makes it possible to quantify the effect of magma contamination by siliceous crust in terms of clinopyroxene-melt element partitioning. Major and trace element partition coefficients have been calculated using the compositions of clinopyroxene rims and glasses next to the crystal surface. Zone 1 and Zone 2 partition coefficients correspond to, respectively, the chemical analyses of Al-rich phenocrysts and matrix glasses, and the chemical analyses of newly-formed Al-poor crystals and hybrid glasses. For clinopyroxenes from both the hybrid layer and the lava flow expected relationships are observed between the partition coefficient, the valence of the element, and the ionic radius. However, with respect to Zone 1 partition coefficients, values of Zone 2 partition coefficients show a net decrease for transition metals (TE), high-field strength elements (HFSE) and rare earth elements including yttrium (REE + Y), and an increase for large ion lithophile elements (LILE). This variation is associated with coupled substitutions on the M1, M2 and T sites of the type M1(Al, Fe3 +) + TAl = M2(Mg, Fe2 +) + TSi. The different incorporation of trace elements into clinopyroxenes of hybrid origin is controlled by cation substitution reactions reflecting local charge-balance requirements. According to the lattice strain theory, simultaneous cation exchanges across the M1, M2, and T sites have profound effects on REE + Y and HFSE partitioning. Conversely, both temperature and melt composition have only a minor effect when the thermal path of magma is restricted to 70 °C and the value of non-bridging oxygens per tetrahedral cations (NBO/T) shifts moderately from 0.31 to 0.43. As a consequence, Zone 2 partition coefficients for REE + Y and HFSE diverge significantly from those derived for Zone 1, accounting for limited cation incorporation into the newly-formed clinopyroxenes at the quartzite-magma interface.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, V.K.; Deevi, S.C.; Fleischhauer, G.S.; Hajaligol, M.R.; Lilly, A.C. Jr.

1997-04-15

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, {<=}1% Cr and either {>=}0.05% Zr or ZrO{sub 2} stringers extending perpendicular to an exposed surface of the heating element or {>=}0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, {<=}2% Ti, {<=}2% Mo, {<=}1% Zr, {<=}1% C, {<=}0.1% B, {<=}30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, {<=}1% rare earth metal, {<=}1% oxygen, {<=}3% Cu, balance Fe. 64 figs.

Geochemical studies of Fe, Mn, Co, As, Cr, Sb, Zn, Sc and V in surface sediments from Jiaozhou Bay

NASA Astrophysics Data System (ADS)

Wu, Run; Li, Pei-Quan; Miao, Lu-Tian; Zhang, Shu-Xin; Tian, Wei-Zhi

1994-12-01

The contents of nearly forty-elements in surface sediments in Jiaozhou Bay were determined using a Neutron Activation Analysis Technique (Grancini, et al., 1976; Li Peiquan et al., 1985, 1986; Li Xiuxia et al., 1986). This paper's detailed discussion on only nine elements (Fe, Mn, Co, Cr, Sc, As, Sb, Zn and V) includes their distributions, concentrations, correlationships, material sources, background, etc. Based on Zavaristski's classification method, Fe, Mn, Co, Cr and V belong to the second group; As and Sb to the eighth groups: Sc and Zn to the third and sixth groups. It was found that their notably good correlationship is mainly due to the similarity of their ionic structures and that their variation is controlled by the Fe content (except Mn). The source of sediments is mainly terristrial material, and the composition of sediment is similar to that of shale and shale+clay. The contents for a large number of elements are within the scope of the background level, but there still is pollution of Zn and Cr, at least in a few stations.

Controls on foliar nutrient and aluminium concentrations in a tropical tree flora: phylogeny, soil chemistry and interactions among elements.

PubMed

Metali, Faizah; Abu Salim, Kamariah; Tennakoon, Kushan; Burslem, David F R P

2015-01-01

Foliar elemental concentrations are predictors of life-history variation and contribute to spatial patterns in biogeochemical cycling. We examined the contributions of habitat association, local soil environment, and elemental interactions to variation in foliar elemental concentrations in tropical trees using methods that account for phylogeny. We sampled top-soils and leaves of 58 tropical trees in heath forest (HF) on nutrient-poor sand and mixed dipterocarp forest (MDF) on nutrient-rich clay soils. A phylogenetic generalized least squares method was used to determine how foliar nutrient and aluminium (Al) concentrations varied in response to habitat distribution, soil chemistry and other elemental concentrations. Foliar nitrogen (N) and Al concentrations were greater for specialists of MDF than for specialists of HF, while foliar calcium (Ca) concentrations showed the opposite trend. Foliar magnesium (Mg) concentrations were lower for generalists than for MDF specialists. Foliar element concentrations were correlated with fine-scale variation in soil chemistry in phylogenetically controlled analyses across species, but there was limited within-species plasticity in foliar elemental concentrations. Among Al accumulators, foliar Al concentration was positively associated with foliar Ca and Mg concentrations, and negatively associated with foliar phosphorus (P) concentrations. The Al-accumulation trait and relationships between foliar elemental and Al concentrations may contribute to species habitat partitioning and ecosystem-level differences in biogeochemical cycles. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

High-temperature site preference and atomic short-range ordering characteristics of ternary alloying elements in γ'-Ni3Al intermetallics

NASA Astrophysics Data System (ADS)

Eriş, Rasim; Mekhrabov, Amdulla O.; Akdeniz, M. Vedat

2017-10-01

Remarkable high-temperature mechanical properties of nickel-based superalloys are correlated with the arrangement of ternary alloying elements in L12-type-ordered γ‧-Ni3Al intermetallics. In the current study, therefore, high-temperature site occupancy preference and energetic-structural characteristics of atomic short-range ordering (SRO) of ternary alloying X elements (X = Mo, W, Ta, Hf, Re, Ru, Pt or Co) in Ni75Al21.875X3.125 alloy systems have been studied by combining the statistico-thermodynamical theory of ordering and electronic theory of alloys in the pseudopotential approximation. Temperature dependence of site occupancy tendencies of alloying X element atoms has been predicted by calculating partial ordering energies and SRO parameters of Ni-Al, Ni-X and Al-X atomic pairs. It is shown that, all ternary alloying element atoms (except Pt) tend to occupy Al, whereas Pt atoms prefer to substitute for Ni sub-lattice sites of Ni3Al intermetallics. However, in contrast to other X elements, sub-lattice site occupancy characteristics of Re atoms appear to be both temperature- and composition-dependent. Theoretical calculations reveal that site occupancy preference of Re atoms switches from Al to both Ni and Al sites at critical temperatures, Tc, for Re > 2.35 at%. Distribution of Re atoms at both Ni and Al sub-lattice sites above Tc may lead to localised supersaturation of the parent Ni3Al phase and makes possible the formation of topologically close-packed (TCP) phases. The results of the current theoretical and simulation study are consistent with other theoretical and experimental investigations published in the literature.

Response of Cr and Cr-Al coatings on Zircaloy-2 to high temperature steam

NASA Astrophysics Data System (ADS)

Zhong, Weicheng; Mouche, Peter A.; Heuser, Brent J.

2018-01-01

The oxidation behavior of chromium (Cr) and chromium-aluminum (CrAl) coatings with various compositions deposited on Zircaloy-2 to 700 °C high-temperature steam (HTS) exposure has been investigated. CrAl coatings with higher Al compositions demonstrate lower oxidation weight gain. A layer of γ-alumina developed on the CrAl coatings with Al composition over 43 at%, while Al2O3 and Cr2O3 developed on CrAl coatings with Al composition below 33 at%. Oxidation of Zircaloy-2 substrate was inhibited by the 1um coatings to 20 h HTS exposure. Coating constituent elements diffused into the substrate and formed intermetallic phases with the Zircaloy substrate. Thicker layers of intermetallic phases developed on the coatings with higher Al composition. The intermetallic phases included Fe and Ni, indicating the dissolution of second phase particles (SPPs) during HTS exposure.

Quantitative analysis of major elements in silicate minerals and glasses by micro-PIXE

USGS Publications Warehouse

Campbell, J.L.; Czamanske, G.K.; MacDonald, L.; Teesdale, W.J.

1997-01-01

The Guelph micro-PIXE facility has been modified to accommodate a second Si(Li) X-ray detector which records the spectrum due to light major elements (11 ??? Z ??? 20) with no deleterious effects from scattered 3 MeV protons. Spectra have been recorded from 30 well-characterized materials, including a broad range of silicate minerals and both natural and synthetic glasses. Sodium is mobile in some of the glasses, but not in the studied mineral lattices. The mean value of the instrumental constant H for each of the elements Mg, Al, and Si in these materials is systematically 6-8% lower than the H-value measured for the pure metals. Normalization factors are derived which permit the matrix corrections requisite for trace-element measurements in silicates to be based upon pure metal standards for Mg, Al and Si, supplemented by well-established, silicate mineral standards for the elements Na, K and Ca. Rigorous comparisons of electron microprobe and micro-PIXE analyses for the entire, 30-sample suite demonstrate the ability of micro-PIXE to produce accurate analysis for the light major elements in silicates. ?? 1997 Elsevier Science B.V.

The peculiar Na-O anticorrelation of the bulge globular cluster NGC 6440

NASA Astrophysics Data System (ADS)

Muñoz, C.; Villanova, S.; Geisler, D.; Saviane, I.; Dias, B.; Cohen, R. E.; Mauro, F.

2017-08-01

Context. Galactic globular clusters (GCs) are essential tools for understanding the earliest epoch of the Milky Way, since they are among the oldest objects in the Universe and can be used to trace its formation and evolution. Current studies using high-resolution spectroscopy for many stars in each of a large sample of GCs allow us to develop a detailed observational picture of their formation and their relation with the Galaxy. However, it is necessary to complete this picture by including GCs that belong to all major Galactic components, including the bulge. Aims: Our aim is to perform a detailed chemical analysis of the bulge GC NGC 6440 in order to determine if this object has multiple populations (MPs) and investigate its relation with the bulge of the Milky Way and with the other Galactic GCs, especially those associated with the bulge, which are largely poorly studied. Methods: We determined the stellar parameters and the chemical abundances of light elements (Na, Al), iron-peak elements (Fe, Sc, Mn, Co, Ni), α-elements (O, Mg, Si, Ca, Ti) and heavy elements (Ba, Eu) in seven red giant members of NGC 6440 using high-resolution spectroscopy from FLAMES-UVES. Results: We found a mean iron content of [Fe/H] =-0.50 ± 0.03 dex in agreement with other studies. We found no internal iron spread. On the other hand, Na and Al show a significant intrinsic spread, but the cluster has no significant O-Na anticorrelation nor does it exhibit a Mg-Al anticorrelation. The α-elements show good agreement with the bulge field star trend, although they are at the high alpha end and are also higher than those of other GCs of comparable metallicity. The heavy elements are dominated by the r-process, indicating a strong contribution by SNeII. The chemical analysis suggests an origin similar to that of the bulge field stars.

Non-CI refractory lithophile abundances in bulk planetary materials

NASA Astrophysics Data System (ADS)

Dauphas, N.

2015-12-01

Refractory inclusions in meteorites show evidence for fractionation of refractory lithophile elements relative to one another. For bulk planetary materials, it is most often assumed that refractory lithophile elements (e.g., Ca, Al, Ti, REEs) are in proportions similar to CI carbonaceous chondrites, which is taken to be a proxy for solar composition. A diagnostic feature of REE patterns in refractory inclusions in meteorites is the presence of thulium anomalies, arising from the fact that this heavy REE is more volatile than the highly refractory HREEs surrounding it (Tm/Tm* is defined relative to either Er-Yb or Er-Lu). Tm anomalies thus represent an excellent diagnostic tool to test the assumption that refractory lithophile elements have uniform relative abundances at a bulk planetary scale. Prior to this work, high precision Tm measurements were lacking because it is mono-isotopic and as such is not amenable to high-precision single spike measurements. We have developed a multi-collector REE abundance measurement technique to measure all REEs at high precision, including the mono-isotopic ones. This technique was used to revise the abundance of CI and PAAS REE abundances (Pourmand et al. 2012) and the CI composition agrees well with an independent study (Barrat et al. 2012). The same technique was applied to measure REE patterns in 41 chondrites as well as terrestrial rocks (Dauphas and Pourmand, 2015). Our results reveal the presence of Tm anomalies of about -4.5 % in terrestrial rocks, enstatite and ordinary chondrites, relative to carbonaceous chondrites including CIs. This demonstrates that the assumption that refractory lithophile elements are in constant proportions among planetary bodies is unwarranted. It also shows that carbonaceous chondrites cannot be a major constituent of the Earth. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust or (ii) CI are enriched in refractory dust and are not representative of solar composition for refractory elements. Barrat J.A. et al. (2012) GCA 83, 79-92. Dauphas N., Pourmand A. (2015) GCA 163, 234-261. Pourmand et al. (2012) Chem. Geol. 291, 38-54.

Saudi Governmental Structure and Foreign Policy

DTIC Science & Technology

1993-01-21

goNrUnent Igeny. SAUDI GOVERNMENTAL STRUCTURE AND FOREIGN POLICY BY COLONEL AL-MUTAIRI NAIF Saudi National Guard DISTRI1BUTION STATEMENT A: Approved for...TASK IWOX UNIT ELEMENT NO. NO. NO. AE NO. 11. TITLE (Include Security Classification) Saudi Governmental Structure and Foreign Policy - Uncl 12... STRUCTURE AND FOREIGN POLICY AN INDIVIDUAL STUDY PROJECT by Colonel al-Mutairi Naif Saudi National Guard Mr. James J. Coyle (Project Adviser) IL

Major and trace (including REEs) element stratigraphy in the first 90 m (around 1 Myr) of ANDRILL AND-1B drillcore.

NASA Astrophysics Data System (ADS)

Rugi, Francesco; Becagli, Silvia; Ghedini, Costanza; Severi, Mirko; Traversi, Rita; Udisti, Roberto; Monien, Donata; Kuhn, Gerhard; Giorgetti, Giovanna; Talarico, Franco

2010-05-01

An integrated system Inductively Coupled Plasma - Sector Field Mass Spectrometry (ICP-SFMS) and Inductively Coupled Plasma - Atomic Emission Spectrophotometry (ICP - AES) has been applied to quantify 39 major and trace elements (including Rare Earths Elements -REE) in Antarctic glaciomarine sediments collected in the framework of ANDRILL. This project aims to study the role of the Antarctic Continent within the global climatic system, by the recovery and analysis of two deep sediment cores (AND-1B, MIS and AND-2A, SMS), drilled close to the margin of the Ross Ice Shelf. The main goals of ANDRILL were to obtain a stratigraphic record that documents key steps in Antarctica's Cenozoic climatic and glacial history, and in the tectonic evolution of the Transantarctic Mountains and the West Antarctic rift System. In particular, the study of the geochemical composition of sediments along the two ANDRILL cores can provide information about the possible source of terrigenous material deposited over the drilling site (Harwood et al., 2006). Preliminary results with a spatial resolution of about 1 m for the geochemical composition of the interval 24.66- 85.24 m of depth of marine sediments from AND-1B core covering about the last 1 Ma, are here shown. The concentration ratio of each measured element with respect to Al concentration, used as terrigenous reference, was calculated in order to remove the possible effect on elemental concentrations of differences in average sediment grain-size along the core and possible dilution effects and point out specified metal enrichments. The presented data and depth profiles (e.g. Fe/Al, Mn/Al, Co/Al, Cr/Al, Eu/Al and Europium anomaly) relative to sediments deposited during the last Ma at the MIS site, show an evident discontinuity from samples collected above and below 58.4 m of depth, corresponding to about 0.45 Ma BP, following the latest AND-1B dating model (85.24 m of depth corresponding to about 0.988 Ma; the chronological datum of the sediments is developed from 40Ar/39Ar ages volcanic deposits, Naish et al. 2009). This difference of geochemical composition suggests different rock sources for the material deposited before and after about 0.45 Ma BP. In particular the geochemical composition of the upper sediments is similar to the one of McMurdo Volcanic Group (MVG) whereas the lower sediments are close to the compositions of samples collected in the Transantarctic Mountain (TAM). Such a different composition could be linked to the climatic discontinuity known as Mid-Brunhes Event (MBE), dated 430 Kyr BP, which marks the boundary between two different global climatic conditions, with the youngest part characterized by a larger temperature gap between short and warm interglacials and long and cold glacials, with respect to the oldest part. Bibliography: Harwood, D. et al. (2006), Deep drilling with the ANDRILL program in Antarctica, Sci. Drill., 3, 43-45. Naish T. et al. (2009), Obliquity-paced Pliocene West Antarctic ice sheet oscillations, Nature, 458, 322-328.

Essential trace elements in amyotrophic lateral sclerosis (ALS): Results in a population of a risk area of Italy.

PubMed

Forte, Giovanni; Bocca, Beatrice; Oggiano, Riccardo; Clemente, Simonetta; Asara, Yolande; Sotgiu, Maria Alessandra; Farace, Cristiano; Montella, Andrea; Fois, Alessandro Giuseppe; Malaguarnera, Michele; Pirina, Pietro; Madeddu, Roberto

2017-09-01

Sardinian (Italy) island population has a uniquely high incidence of amyotrophic lateral sclerosis (ALS). Essential trace element levels in blood, hair, and urine of ALS Sardinian patients were investigated in search of valid biomarkers to recognize and predict ALS. Six elements (Ca, Cu, Fe, Mg, Se, and Zn) were measured in 34 patients compared to 30 age- and sex-matched healthy controls by a validated method. Levels of Ca and Cu in blood and of Se and Zn in hair were significantly higher in ALS than in controls, while urinary excretion of Mg and Se was significantly decreased. The selected cut-off concentrations for these biomarkers may distinguish patients with or without ALS with sufficient sensitivity and specificity. Many positive (as Se-Cu and Se-Zn) and negative associations (as Ca-Mg and Ca-Zn) between elements suggested that multiple metals involved in multiple mechanisms have a role in the ALS degeneration.

Geochemical distribution of major and trace elements in agricultural soils of Castilla-La Mancha (central Spain): finding criteria for baselines and delimiting regional anomalies.

PubMed

Bravo, Sandra; García-Ordiales, Efrén; García-Navarro, Francisco Jesús; Amorós, José Ángel; Pérez-de-Los-Reyes, Caridad; Jiménez-Ballesta, Raimundo; Esbrí, José María; García-Noguero, Eva María; Higueras, Pablo

2017-09-07

Castilla-La Mancha (central Spain) is a region characterized by significant agricultural production aimed at high-quality food products such as wine and olive oil. The quality of agricultural products depends directly on the soil quality. Soil geochemistry, including dispersion maps and the recognition of baselines and anomalies of various origins, is the most important tool to assess soil quality. With this objective, 200 soil samples were taken from agricultural areas distributed among the different geological domains present in the region. Analysis of these samples included evaluation of edaphological parameters (reactivity, electrical conductivity, organic matter content) and the geochemistry of major and trace elements by X-ray fluorescence. The dataset obtained was statistically analyzed for major elements and, in the case of trace elements, was normalized with respect to Al and analyzed using the relative cumulative frequency (RCF) distribution method. Furthermore, the geographic distribution of analytical data was characterized and analyzed using the kriging technique, with a correspondence found between major and trace elements in the different geologic domains of the region as well as with the most important mining areas. The results show an influence of the clay fraction present in the soil, which acts as a repository for trace elements. On the basis of the results, of the possible elements related with clay that could be used for normalization, Al was selected as the most suitable, followed by Fe, Mn, and Ti. Reference values estimated using this methodology were lower than those estimated in previous studies.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

1997-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

1999-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Iron aluminide useful as electrical resistance heating elements

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

2001-01-01

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or ZrO.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B, .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Oxidation of nickel-aluminum and iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathcart, J.V.

1985-01-01

The high-temperature oxidation behavior of several ordered alloys in the Ni-Al and Fe-Al systems is reviewed with special emphasis on Ni/sub 3/Al and NiAl. Ordering influences oxidation through its effect on the activities of the alloy components and by changing the point defect concentration in an alloy. Three categories of Ni-Al alloys are distinguished based on Al content and oxidation behavior. A characteristic feature of the oxidation of high-aluminum Ni-Al and Fe-Al alloys is the formation of voids in the substrate at the oxidate-metal interface. The mechanism of void formation and its suppression by minor additions of oxygen-active elements ismore » discussed. A brief description of the effect of preoxidation on the reactions of Ni/sub 3/Al-base alloys in SO/sub 2//O/sub 2/ environments is also included. 51 references, 14 figures, 1 table.« less

Oxidation of nickel-aluminum and iron-aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathcart, J.V.

1984-01-01

The high-temperature oxidation behavior of several ordered alloys in the Ni-Al and Fe-Al systems is reviewed with special emphasis on Ni/sub 3/Al and NiAl. Ordering influences oxidation through its effect on the activities of the alloy components and by changing the point defect concentration in an alloy. Three categories of Ni-Al alloys are distinguished based on Al content and oxidation behavior. A characteristic feature of the oxidation of high-aluminum Ni-Al and Fe-Al alloys is the formation of voids in the substrate at the oxide-metal interface. The mechanism of void formation and its suppression by minor additions of oxygen-active elements aremore » discussed. A brief description of the effect of pre-oxidation on the reactions of Ni/sub 3/Al-base alloys in SO/sub 2//O/sub 2/ environments is also included.« less

Band gap tuning in transition metal oxides by site-specific substitution

DOEpatents

Lee, Ho Nyung; Chisholm, Jr., Matthew F; Jellison, Jr., Gerald Earle; Singh, David J; Choi, Woo Seok

2013-12-24

A transition metal oxide insulator composition having a tuned band gap includes a transition metal oxide having a perovskite or a perovskite-like crystalline structure. The transition metal oxide includes at least one first element selected form the group of Bi, Ca, Ba, Sr, Li, Na, Mg, K, Pb, and Pr; and at least one second element selected from the group of Ti, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Hf, Ta, W, Re, Os, Ir, and Pt. At least one correlated insulator is integrated into the crystalline structure, including REMO.sub.3, wherein RE is at least one Rare Earth element, and wherein M is at least one element selected from the group of Co, V, Cr, Ni, Mn, and Fe. The composition is characterized by a band gap of less of 4.5 eV.

Alloy Design Data Generated for B2-Ordered Compounds

NASA Technical Reports Server (NTRS)

Noebe, Ronald D.; Bozzolo, Guillermo; Abel, Phillip B.

2003-01-01

Developing alloys based on ordered compounds is significantly more complicated than developing designs based on disordered materials. In ordered compounds, the major constituent elements reside on particular sublattices. Therefore, the addition of a ternary element to a binary-ordered compound is complicated by the manner in which the ternary addition is made (at the expense of which binary component). When ternary additions are substituted for the wrong constituent, the physical and mechanical properties usually degrade. In some cases the resulting degradation in properties can be quite severe. For example, adding alloying additions to NiAl in the wrong combination (i.e., alloying additions that prefer the Al sublattice but are added at the expense of Ni) will severely embrittle the alloy to the point that it can literally fall apart during processing on cooling from the molten state. Consequently, alloying additions that strongly prefer one sublattice over another should always be added at the expense of that component during alloy development. Elements that have a very weak preference for a sublattice can usually be safely added at the expense of either element and will accommodate any deviation from stoichiometry by filling in for the deficient component. Unfortunately, this type of information is not known beforehand for most ordered systems. Therefore, a computational survey study, using a recently developed quantum approximate method, was undertaken at the NASA Glenn Research Center to determine the preferred site occupancy of ternary alloying additions to 12 different B2-ordered compounds including NiAl, FeAl, CoAl, CoFe, CoHf, CoTi, FeTi, RuAl, RuSi, RuHf, RuTi, and RuZr. Some of these compounds are potential high temperature structural alloys; others are used in thin-film magnetic and other electronic applications. The results are summarized. The italicized elements represent the previous sum total alloying information known and verify the computational method used to establish the table. Details of the computational procedures used to determine the preferred site occupancy can be found in reference 2. As further substantiation of the validity of the technique, and its extension to even more complicated systems, it was applied to two simultaneous alloying additions in an ordered alloy.

Experimental constraints on Earth's core formation

NASA Astrophysics Data System (ADS)

Bouhifd, Mohamed Ali

2017-04-01

The Earth contains a Fe-rich metallic core that segregated from the primitive silicate mantle very early in its 4.5 billion year history. One major consequence of this segregation is the depletion of the Earth's mantle from the siderophile elements "high core affinity" relative to primitive solar system abundances. The way in which siderophile elements partition between metal and silicate depends strongly on pressure (P), temperature (T), oxygen fugacity (fO2) and chemical compositions of both metal and silicate phases. In the present presentation, I will discuss the experimental results of metal-silicate partitioning of Ni and Co that show a marked change with increasing pressure (e.g. Bouhifd and Jephcoat, 2011; Siebert et al., 2012; Fischer et al., 2015 for the most recent studies). This behavior coincides with a change in the coordination of silicon (in a basaltic melt composition) from 4-fold coordination under ambient conditions to 6-fold coordination at about 35 GPa, indicating that melt compressibility may controls siderophile-element partitioning (Sanloup et al., 2013). I will also discuss the impact of Earth's core formation on "lithophile" elements such as Sm, Nd, Ta and Nb (e.g. Bouhifd et al. 2015; Cartier et al., 2014), as well as the impact of sulphur on the behavior of various elements during core formation (e.g. Boujibar et al., 2014; Wohlers and Wood, 2015). By combining the metal-silicate partitioning data from siderophile, lithophile and chalcophile elements I will present and discuss the most plausible conditions for Earth's core formation. References Bouhifd and Jephcoat (2011) EPSL, 307, 341-348. Bouhifd et al. (2015) EPSL 413, 158-166. Boujibar et al. (2014) EPSL 391, 42-54. Cartier et al. (2014) Nature Geoscience, 7, 573-576. Fischer et al. (2015) GCA 167, 177-194. Sanloup et al. (2013) Nature, 503, 104-107. Siebert et al. (2012) EPSL 321-322, 189-197. Wohlers and Wood (2015) Nature 520, 337-340.

Nanocrystal dispersed amorphous alloys

NASA Technical Reports Server (NTRS)

Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

2001-01-01

Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

NASA Technical Reports Server (NTRS)

Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

2002-01-01

Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

Local melting in Al embedded with TiNi powder induced by microarea self-propagating high-temperature synthesis

NASA Astrophysics Data System (ADS)

Yamamoto, Tokujiro

2014-10-01

Microarea self-propagating high-temperature synthesis (microSHS) was ignited by the heat of mixing generated at the boundaries between an Al matrix and TiNi particles during plastic deformation at room temperature. The temperature of the boundaries was rapidly increased by microSHS; the temperature elevation resulted in local melting of the TiNi particle and the surrounding Al matrix, because the heat of mixing was localized in the vicinity of the TiNi particle although the amount of the heat of mixing was limited. Since the amount of the local melting region induced by microSHS is restricted, not only major elements (i.e. Al, Ti and Ni) but also impurities were involved in the solidification followed by local melting. As a result, ?FeNi nanoprecipitates, which have not been reported in SHS studies, were formed by inclusion of Fe, initially included as an impurity in raw materials. The formation mechanism of ?FeNi nanoprecipitates is discussed based on reference to the Al-Fe-Ni ternary alloy phase diagram. It is expected that local melting induced by microSHS is a key phenomonon for amorphization during severe plastic deformation of elemental sheets.

Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites

PubMed Central

2013-01-01

Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction. PMID:23601907

Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites

NASA Astrophysics Data System (ADS)

Wen, John Z.; Ringuette, Sophie; Bohlouli-Zanjani, Golnaz; Hu, Anming; Nguyen, Ngoc Ha; Persic, John; Petre, Catalin F.; Zhou, Y. Norman

2013-04-01

Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction.

Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites.

PubMed

Wen, John Z; Ringuette, Sophie; Bohlouli-Zanjani, Golnaz; Hu, Anming; Nguyen, Ngoc Ha; Persic, John; Petre, Catalin F; Zhou, Y Norman

2013-04-20

Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction.

Formal Semantics in the Neurology Clinic: Atypical Understanding of Aspectual Coercion in ALS Patients

PubMed Central

Baggio, Giosuè; Granello, Giulia; Verriello, Lorenzo; Eleopra, Roberto

2016-01-01

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of the motor system with subtle adverse effects on cognition. It is still unclear whether ALS also affects language and semantics, and if so, what aspects and processes exactly. We investigated how ALS patients understand verb phrases modified by temporal preposition phrases, e.g., “To watch TV for half an hour.” Interpretation here requires operations such as aspectual coercion that add or delete elements from event structures, depending on temporal modifiers, and constraints on coercion, which make combinations with certain modifiers not viable. Using a theoretically-motivated experimental design, we observed that acceptance rates for aspectual coercion were abnormally high in ALS patients. The effect was largest for the more complex cases of coercion: not those that involve enrichment of event structures (“To switch on the TV in half an hour,” where a number of failed attempts must be included in the interpretation) but those that, if applied, would result in deletion of event structure elements (“To repair the TV for half an hour”). Our experimental results are consistent with a deficit of constraints on coercion, and not with impaired semantic processes or representations, in line with recent studies suggesting that verb semantics is largely spared in ALS. PMID:27867369

Metapopulation Dynamics of the Softshell Clam, Mya arenaria

DTIC Science & Technology

2008-06-01

LA-ICP-MS. J. Anal. At. Spectrom. 17:8-14. ing of gastropod statoliths to study larval dispersal trajecto- Jones, C. M., and Z. Chen. 2003. New...have expanded the use of elemental tags to inver- tebrates including decapods (DiBacco and Levin, 2000), gastropods (Zacherl et al., 2003a), bivalves...shell uptake has been examined only in one gastropod (Zacherl et al., 2003b) and in no bivalves. We explored the relationships between temperature

Statistical analysis of soil geochemical data to identify pathfinders associated with mineral deposits: An example from the Coles Hill uranium deposit, Virginia, USA

USGS Publications Warehouse

Levitan, Denise M.; Zipper, Carl E.; Donovan, Patricia; Schreiber, Madeline E.; Seal, Robert; Engle, Mark A.; Chermak, John A.; Bodnar, Robert J.; Johnson, Daniel K.; Aylor, Joseph G.

2015-01-01

Soil geochemical anomalies can be used to identify pathfinders in exploration for ore deposits. In this study, compositional data analysis is used with multivariate statistical methods to analyse soil geochemical data collected from the Coles Hill uranium deposit, Virginia, USA, to identify pathfinders associated with this deposit. Elemental compositions and relationships were compared between the collected Coles Hill soil and reference soil samples extracted from a regional subset of a national-scale geochemical survey. Results show that pathfinders for the Coles Hill deposit include light rare earth elements (La and Ce), which, when normalised by their Al content, are correlated with U/Al, and elevated Th/Al values, which are not correlated with U/Al, supporting decoupling of U from Th during soil generation. These results can be used in genetic and weathering models of the Coles Hill deposit, and can also be applied to future prospecting for similar U deposits in the eastern United States, and in regions with similar geological/climatic conditions.

Heterogeneity of Multimedia Exposures to Neurotoxic Elements (Al, As, Cd, Pb, Mn, and Hg) in Breastfed Infants from Porto Velho, Brazil.

PubMed

Bastos, Wanderley R; Vieira, Solange M; Manzatto, Ângelo G; Dórea, José G; Rubira, Marcelo C; de Souza, Victor Francisco P; da Costa Junior, Walkimar A; Souza Bastos, Maria T

2017-10-01

Infant exposure to neurotoxic elements is a public health issue that needs monitoring with regard to breast milk composition. We studied six neurotoxic elements in breast milk samples at different stages of lactation in mothers from Porto Velho, Brazil. We used a flow-injection mercury system (FIMS) to determine total Hg concentrations and an inductively coupled plasma optical emission spectrometer (ICP-OES) to determine the concentrations of Al, As, Cd, Pb, and Mn in 106 donors of a human milk bank. Association rules analyses were applied to determine the pattern of binary and ternary mixtures of the measured exposants. The metal concentration was mostly below the limit of detection (LOD) for Cd (99%), Pb (84%), and Hg (72%), and it was above the LOD for As (53%), Mn (60%), and Al (82%), respectively. Median concentrations (dry weight) of Al, As, Hg, Mn, and Pb were 1.81 μg/g, 13.8 ng/g, 7.1 ng/g, 51.1 ng/g, and 0.43 μg/g, respectively. Al is singly the most frequent element to which infants are exposed. Occurring binary combination (> LOD) was 56% for Al-Mn, 41% for Al-As, 22% for Al-Hg, and 13% for Al-Pb. In 100% of neonates, exposure to Al-ethylmercury (EtHg) occurred through immunization with thimerosal-containing vaccines (TCV). Association rules analysis revealed that Al was present in all of the multilevel combinations and hierarchical levels and that it showed a strong link with other neurotoxic elements (especially with Mn, As, and Hg). (a) Nursing infants are exposed to combinations of neurotoxicants by different routes, dosages, and at different stages of development; (b) In breastfed infants, the binary exposures to Al and total Hg can occur through breast milk and additionally through TCV (EtHg and Al); (c) The measured neurotoxic elements were found at low frequencies in breast milk and at concentrations that pose no public health concerns for milk banking.

Fatigue behavior of Long and Short Cracks in Aluminum Alloys.

DTIC Science & Technology

1987-05-01

Mughrabi : in ’Strength ,f met als ind 121. S. Suresh. D. M. Parks, and R.0. Ritchie: in allws’. (ed. P. Haasen (,t %i. V I. Fatigue thresholds’, ed. J...RITCHIE ET AL . ft MAY 67 W ASSIFED UC/RP/ /A14 AFOSR-TR-B7- F/O 1.1NML LEhEEINOE2 hohEE ’EhmhELIEEmhEsh EEEmohhhhhhEEEE EEEmhEEEmhhEEI...TASK IWORK UNIT ELEMENT NO. NO. NO. ACCESSION NO. 0,0 61102F 2306 Al 11. TITLE Include Security Clasfication) FATIGUE BEHAVIOR OF LONG AND SHORT

Introductory Laboratory Exercises in Radiobiology

ERIC Educational Resources Information Center

Williams, J. R. Parry; Servant, D. M.

1970-01-01

Describes experiments suitable for introducing use of radioisotopes in biology. Includes demonstrations of tracing food chains, uptake of ions by plants, concentration of elements by insects, tracing photosynthetic reactions, activation analysis of copper, and somatic and genetic effects. Uses autoradiographic and counting techniques. (AL)

The relationship between structural stability and electrochemical performance of multi-element doped alpha nickel hydroxide

NASA Astrophysics Data System (ADS)

Miao, Chengcheng; Zhu, Yanjuan; Huang, Liangguo; Zhao, Tengqi

2015-01-01

The multi-element doped alpha nickel hydroxide has been prepared by supersonic co-precipitation method. Three kinds of samples A, B and C are prepared by chemically coprecipitating Ni/Al, Ni/Al/Mn and Ni/Al/Mn/Yb, respectively. Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Particle size distribution (PSD) measurement, X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the physical properties of the synthesized α-Ni(OH)2 samples, such as chemical composition, morphology, structural stability of the crystal. The results show that all samples are nano-sized materials and the interlayer spacing becomes larger and the structural stability becomes better with the increase of doped elements and doped ratio. The prepared alpha nickel hydroxide samples are added into micro-sized beta nickel hydroxide to form biphase electrode materials for Ni-MH battery. The electrochemical characterization of the biphase electrodes, including cyclic voltammetry (CV) and charge/discharge test, are also performed. The results demonstrate that the biphase electrode with sample C exhibits better electrochemical reversibility and cyclic stability, higher charge efficient and discharge potential, larger proton diffusion coefficient (5.81 × 10-12 cm2 s-1) and discharge capacity (309.0 mAh g-1). Hence, it indicates that all doped elements can produce the synergic effect and further improve the electrochemical properties of the alpha nickel hydroxide.

Model of Silicon Refining During Tapping: Removal of Ca, Al, and Other Selected Element Groups

NASA Astrophysics Data System (ADS)

Olsen, Jan Erik; Kero, Ida T.; Engh, Thorvald A.; Tranell, Gabriella

2017-04-01

A mathematical model for industrial refining of silicon alloys has been developed for the so-called oxidative ladle refining process. It is a lumped (zero-dimensional) model, based on the mass balances of metal, slag, and gas in the ladle, developed to operate with relatively short computational times for the sake of industrial relevance. The model accounts for a semi-continuous process which includes both the tapping and post-tapping refining stages. It predicts the concentrations of Ca, Al, and trace elements, most notably the alkaline metals, alkaline earth metal, and rare earth metals. The predictive power of the model depends on the quality of the model coefficients, the kinetic coefficient, τ, and the equilibrium partition coefficient, L for a given element. A sensitivity analysis indicates that the model results are most sensitive to L. The model has been compared to industrial measurement data and found to be able to qualitatively, and to some extent quantitatively, predict the data. The model is very well suited for alkaline and alkaline earth metals which respond relatively fast to the refining process. The model is less well suited for elements such as the lanthanides and Al, which are refined more slowly. A major challenge for the prediction of the behavior of the rare earth metals is that reliable thermodynamic data for true equilibrium conditions relevant to the industrial process is not typically available in literature.

AN ELEMENTAL ASSAY OF VERY, EXTREMELY, AND ULTRA-METAL-POOR STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, T.; Christlieb, N.; Hansen, C. J.

2015-07-10

We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H] < −2.0) stars, 12 of which are extremely metal-poor ([Fe/H] < −3.0), and 4 of which are ultra-metal-poor ([Fe/H] < −4.0). These stars were targeted to explore differences in the abundance ratios for elements that constrain the possible astrophysical sites of element production, including Li, C, N, O, the α-elements, the iron-peak elements, and a number of neutron-capture elements. This sample substantially increases the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars—our program stars include eight that are considered “normal” metal-poor stars, sixmore » CEMP-no stars, five CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. We detect lithium for three of the six CEMP-no stars, all of which are Li depleted with respect to the Spite plateau. The majority of the CEMP stars have [C/N] > 0. The stars with [C/N] < 0 suggest a larger degree of mixing; the few CEMP-no stars that exhibit this signature are only found at [Fe/H] < −3.4, a metallicity below which we also find the CEMP-no stars with large enhancements in Na, Mg, and Al. We confirm the existence of two plateaus in the absolute carbon abundances of CEMP stars, as suggested by Spite et al. We also present evidence for a “floor” in the absolute Ba abundances of CEMP-no stars at A(Ba) ∼ −2.0.« less

Studies of biaxial mechanical properties and nonlinear finite element modeling of skin.

PubMed

Shang, Xituan; Yen, Michael R T; Gaber, M Waleed

2010-06-01

The objective of this research is to conduct mechanical property studies of skin from two individual but potentially connected aspects. One is to determine the mechanical properties of the skin experimentally by biaxial tests, and the other is to use the finite element method to model the skin properties. Dynamic biaxial tests were performed on 16 pieces of abdominal skin specimen from rats. Typical biaxial stress-strain responses show that skin possesses anisotropy, nonlinearity and hysteresis. To describe the stress-strain relationship in forms of strain energy function, the material constants of each specimen were obtained and the results show a high correlation between theory and experiments. Based on the experimental results, a finite element model of skin was built to model the skin's special properties including anisotropy and nonlinearity. This model was based on Arruda and Boyce's eight-chain model and Bischoff et al.'s finite element model of skin. The simulation results show that the isotropic, nonlinear eight-chain model could predict the skin's anisotropic and nonlinear responses to biaxial loading by the presence of an anisotropic prestress state.

Process for synthesizing compounds from elemental powders and product

DOEpatents

Rabin, B.H.; Wright, R.N.

1993-12-14

A process for synthesizing intermetallic compounds from elemental powders is described. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe[sub 3] Al and FeAl. 25 figures.

Process for synthesizing compounds from elemental powders and product

DOEpatents

Rabin, Barry H.; Wright, Richard N.

1993-01-01

A process for synthesizing intermetallic compounds from elemental powders. The elemental powders are initially combined in a ratio which approximates the stoichiometric composition of the intermetallic compound. The mixed powders are then formed into a compact which is heat treated at a controlled rate of heating such that an exothermic reaction between the elements is initiated. The heat treatment may be performed under controlled conditions ranging from a vacuum (pressureless sintering) to compression (hot pressing) to produce a desired densification of the intermetallic compound. In a preferred form of the invention, elemental powders of Fe and Al are combined to form aluminide compounds of Fe.sub.3 Al and FeAl.

Characterization and source identification of trace elements in airborne particulates at urban and suburban atmospheres of Tabriz, Iran.

PubMed

Gholampour, Akbar; Nabizadeh, Ramin; Hassanvand, Mohammad Sadegh; Taghipour, Hasan; Rafee, Mohammad; Alizadeh, Zahra; Faridi, Sasan; Mahvi, Amir Hossein

2016-01-01

Concentration of particulate matter (PM10 and total suspended particulate (TSP)) and their elemental constituents were measured to identify the major sources of elements in urban and industrial suburban sites in Tabriz, Iran, from September 2012 to June 2013. TSP and PM10 samples were collected using high-volume samplers. Concentrations of 31 elements in aerosols and crustal soil were determined by ICPMS. The most abundant detected metals in the urban sampling sites were Al (217.5-4019.9 ng m(-3)), Fe (272.5-7658.0 ng m(-3)), Pt (4.7-1994.4 ng m(-3)), and P (13.6-2054.8 ng m(-3) (for TSP and Al (217.6-3687.3 ng m(-3)), Fe (197.1-3724.9 ng m(-3)), Pt (65.9-2054.5 ng m(-3)), and P (11.0-756.6 ng m(-3)( for PM10. In the suburban sampling site, the most abundant detected metals were Al (2083.0-9664.0 ng m(-3)), Fe (360.0-7221.5 ng m(-3)), P (229.4-870.5 ng m(-3)), and Ti (137.3-849.7 ng m(-3)) for TSP and Al (218.5-4179.6 ng m(-3)), Fe (106.3-2005.1 ng m(-3)), P (251.9-908.4 ng m(-3)), and Ba (10.6-584.9 ng m(-3)) for PM10. For the crustal soil, the most abundant detected elements included Al (60,088-60,694 ppm), Fe (19,886-20,474 ppm), Ti (894-3481 ppm), and Si (365-4246 ppm). Key emission sources were identified, and the concentrations contributed from individual sources were estimated. Enrichment factor (EF) explaining a preponderance of the variance in the data was applied to the datasets. EF calculations revealed that non-crustal trace elements were more enriched in the urban than suburban sampling sites. Results of the factor analysis on the elements showed that emissions from road traffic (involving oil and fuel combustions by vehicles, platinum group elements from vehicle exhaust, and resuspension of particulate matter from polluted soil) and construction dust from nearby construction sites and electricity generation plant were the major contributors of anthropogenic metals at ambient atmosphere in Tabriz. Results of this study elucidated the need for developing pollution control strategy, especially vehicle exhaust control, and creating green spaces around the city.

Geochemical and biogeochemical investigations in national parks [Badania geochemiczne i biogeochemiczne w parkach narodowych

USGS Publications Warehouse

Migaszewski, Z.M.; Lamothe, P.J.; Crock, J.G.

1998-01-01

National parks hold a key position among nature protection areas including a diversity of resources - natural, cultural, recreational and scenic. These "inviolable sanctuaries" are simultaneosuly ecologic knots and pristine nature refuges due to the presence of a number of unique plant and animal species. These species make up a natural gene bank. Classically, the level of biologic degradation in national parks is determined on the basis of qualitative and quantitative studies of plant bioindicators. Their scope encompasses phytosociologic survey the purpose of which is to identify floral assemblages with a detailed list of species to record future changes in their number. The best biomonitors of air quality are epiphytic lichens, ground mosses and conifers. Geochemical and biogeochemical investigations are widely performed in the U.S.A. to evaluate the degree of pollution in the nature protection areas including national parks (Gough et al., 1988a, b; Crock et al., 1992a, 1993; Jackson et al., 1995). Variability of element concentrations in soils and plants is assessed by using unbalanced, nested analysis-of-variance (ANOVA). It enables obtaining important statistical information with a minimum number of samples. In some cases a combined grid and barbell sampling design is applied (Jackson et al., 1995). In specific mountainous parks a method of 2-3 transects parallel to the extent of range (crest) is recommended. To determine the impact of a single pollution source on a given park, traverse sampling beginning near the emitter is used (Crock et al., 1992, 1993). The obtained results are a "snapshot" of chemical composition of soils and plant bioindicators that can be a reference for any future changes in the concentration level of chemical elements and organics. In addition, baseline element and organics composition of the media mentioned above can be compared with that obtained for geochemical atlases of polluted urban and industrial areas. Geochemical and biogeochemical investigations are also used for determining natural or anthropogenic sources of pollution. The best way to trace them is sulfur isotopes (Jackson et al., 1996).

Geochemical fingerprinting and source discrimination in soils at the continental scale

NASA Astrophysics Data System (ADS)

Negrel, Philippe; Sadeghi, Martiya; Ladenberger, Anna; Birke, Manfred; Reimann, Clemens

2014-05-01

Agricultural soil (Ap-horizon, 0-20 cm) samples were collected from a large part of Europe (33 countries, 5.6 million km2) at an average density of 1 sample site per 2500 km2. The resulting 2108 soil samples were air dried, sieved to <2 mm, milled and analysed for their major and trace element concentrations by wavelength dispersive X-ray fluorescence spectrometry (WD-XRF). The main goal of this study is to provide a global view of element mobility and source rocks at the continent scale, either by reference to crustal evolution or normalized patterns of element mobility during weathering processes. The survey area includes several sedimentary basins with different geological history, developed in different climate zones and landscapes and with different land use. In order to normalize the chemical composition of soils, mean values and standard deviation of the selected elements have been checked against values for the upper continental crust (UCC). Some elements turned out to be enriched relative to the UCC (Al, P, Zr, Pb) whereas others, like Mg, Na, Sr and Pb were depleted with regards to the variation represented by the standard deviation. The concept of UCC extended normalization patterns have been further used for the selected elements. The mean value of Rb, K, Y, Ti, Al, Si, Zr, Ce and Fe are very close to the UCC model even if standard deviation suggests slight enrichment or depletion, and Zr shows the best fit with the UCC model using both mean value and standard deviation. Lead and Cr are enriched in European soils when compared to UCC but their standard deviation values show very large variations, particularly towards very low values, which can be interpreted as a lithological effect. Element variability has been explored by looking at the variations using indicator elements. Soil data have been converted into Al-normalized enrichment factors and Na was applied as normalizing element for studying provenance source taking into account the main lithologies of the UCC. This latter normalization highlighted variations related to the soluble and insoluble behavior of some elements (K, Rb versus Ti, Al, Si, V, Y, Zr, Ba, and La, respectively), their reactivity (Fe, Mn, Zn), association with carbonates (Ca and Sr) and with phosphates (P and Ce). The maps of normalized composition revealed some problems with use of classical element ratios due to genetical differences in composition of parent material reflected, for example, in large differences in titanium content in bedrock and soil throughout the Europe.

Concentration of stable elements in food products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montford, M.A.; Shank, K.E.; Hendricks, C.

1980-01-01

Food samples were taken from commercial markets and analyzed for stable element content. The concentrations of most stable elements (Ag, Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Fe, Hf, I, K, La, Mg, Mn, Mo, Na, Rb, Sb, Sc, Se, Sr, Ta, Th, Ti, V, Zn, Zr) were determined using multiple-element neutron activation analysis, while the concentrations of other elements (Cd, Hg, Ni, Pb) were determined using atomic absorption. The relevance of the concentrations found are noted in relation to other literature values. An earlier study was extended to include the determination of the concentrationmore » of stable elements in home-grown products in the vicinity of the Oak Ridge National Laboratory. Comparisons between the commercial and local food-stuff values are discussed.« less

A Large C+N+O Abundance Spread in Giant Stars of the Globular Cluster NGC 1851

NASA Astrophysics Data System (ADS)

Yong, David; Grundahl, Frank; D'Antona, Francesca; Karakas, Amanda I.; Lattanzio, John C.; Norris, John E.

2009-04-01

Abundances of C, N, and O are determined in four bright red giants that span the known abundance range for light (Na and Al) and s-process (Zr and La) elements in the globular cluster NGC 1851. The abundance sum C+N+O exhibits a range of 0.6 dex, a factor of 4, in contrast to other clusters in which no significant C+N+O spread is found. Such an abundance range offers support for the Cassisi et al. scenario in which the double subgiant branch populations are coeval but with different mixtures of C+N+O abundances. Further, the Na, Al, Zr, and La abundances are correlated with C+N+O, and therefore NGC 1851 is the first cluster to provide strong support for the scenario in which asymptotic giant branch stars are responsible for the globular cluster light element abundance variations. This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

The reactive element effect of yttrium and yttrium silicon on high temperature oxidation of NiCrAl coating

NASA Astrophysics Data System (ADS)

Ramandhany, S.; Sugiarti, E.; Desiati, R. D.; Martides, E.; Junianto, E.; Prawara, B.; Sukarto, A.; Tjahjono, A.

2018-03-01

The microstructure formed on the bond coat affects the oxidation resistance, particularly the formation of a protective oxide layer. The adhesion of bond coat and TGO increased significantly by addition of reactive element. In the present work, the effect of yttrium and yttrium silicon as reactive element (RE) on NiCrAl coating was investigated. The NiCrAl (without RE) and NiCrAlX (X:Y or YSi) bond coating were deposited on Hastelloy C-276 substrate by High Velocity Oxygen Fuel (HVOF) method. Isothermal oxidation was carried out at 1000 °C for 100 hours. The results showed that the addition of RE could prevent the breakaway oxidation. Therefore, the coating with reactive element were more protective against high temperature oxidation. Furthermore, the oxidation rate of NiCrAlY coating was lower than NiCrAlYSi coating with the total mass change was ±2.394 mg/cm2 after 100 hours of oxidation. The thickness of oxide scale was approximately 1.18 μm consisting of duplex oxide scale of spinel NiCr2O4 in outer scale and protective α-Al2O3 in inner scale.

Evaluation of occupational exposure to toxic metals released in the process of aluminum welding.

PubMed

Matczak, Wanda; Gromiec, Jan

2002-04-01

The objective of this study was to evaluate occupational exposure to welding fumes and its elements on aluminum welders in Polish industry. The study included 52 MIG/Al fume samples and 18 TIG/Al samples in 3 plants. Air samples were collected in the breathing zone of welders (total and respirable dust). Dust concentration was determined gravimetrically, and the elements in the collected dust were determined by AAS. Mean time-weighted average (TWA) concentrations of the welding dusts/fumes and their components in the breathing zone obtained for different welding processes were, in mg/m3: MIG/Al fumes mean 6.0 (0.8-17.8), Al 2.1 (0.1-7.7), Mg 0.2 (< 0.1-0.9), Mn 0.014 (0.002-0.049), Cu 0.011 (0.002-0.092), Zn 0.016 (0.002-0.14), Pb 0.009 (0.005-0.025), Cr 0.003 (0.002-0.007), and TIG/Al fumes 0.7 (0.3-1.4), Al 0.17 (0.07-0.50). A correlation has been found between the concentration of the main components and the fume/dust concentrations in MIG/Al and TIG/Al fumes. Mean percentages of the individual components in MIG/Al fumes/dusts were Al: 30 (9-56) percent; Mg: 3 (1-5.6) percent; Mn: 0.2 (0.1-0.3) percent; Cu: 0.2 (< 0.1-1.8) percent; Zn: 0.2 (< 0.1-0.8) percent; Pb: 0.2 (< 0.1-1) percent; Cr: < 0.1 percent. The proportion of the respirable fraction in the fumes and their constituents varied between 10 percent and 100 percent. The results showed that MIG/Al fumes concentration was 1.2 times higher than the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV), and the index of the combined exposure to the determined agents was 2.3 (0.4-8.0), mostly because of high Al2O3 contribution. The background concentrations of the components (ca. 5-10 times lower than those in the breathing zone of the welders) did not exceed the Polish MAC value. The elemental composition of total and respirable fume/dust may differ considerably depending on welding methods, the nature of welding-related operations, and work environment conditions.

An Anisotropic A posteriori Error Estimator for CFD

NASA Astrophysics Data System (ADS)

Feijóo, Raúl A.; Padra, Claudio; Quintana, Fernando

In this article, a robust anisotropic adaptive algorithm is presented, to solve compressible-flow equations using a stabilized CFD solver and automatic mesh generators. The association includes a mesh generator, a flow solver, and an a posteriori error-estimator code. The estimator was selected among several choices available (Almeida et al. (2000). Comput. Methods Appl. Mech. Engng, 182, 379-400; Borges et al. (1998). "Computational mechanics: new trends and applications". Proceedings of the 4th World Congress on Computational Mechanics, Bs.As., Argentina) giving a powerful computational tool. The main aim is to capture solution discontinuities, in this case, shocks, using the least amount of computational resources, i.e. elements, compatible with a solution of good quality. This leads to high aspect-ratio elements (stretching). To achieve this, a directional error estimator was specifically selected. The numerical results show good behavior of the error estimator, resulting in strongly-adapted meshes in few steps, typically three or four iterations, enough to capture shocks using a moderate and well-distributed amount of elements.

Prediction and synthesis of a family of atomic laminate phases with Kagomé-like and in-plane chemical ordering

PubMed Central

Dahlqvist, Martin; Lu, Jun; Meshkian, Rahele; Tao, Quanzheng; Hultman, Lars; Rosen, Johanna

2017-01-01

The enigma of MAX phases and their hybrids prevails. We probe transition metal (M) alloying in MAX phases for metal size, electronegativity, and electron configuration, and discover ordering in these MAX hybrids, namely, (V2/3Zr1/3)2AlC and (Mo2/3Y1/3)2AlC. Predictive theory and verifying materials synthesis, including a judicious choice of alloying M from groups III to VI and periods 4 and 5, indicate a potentially large family of thermodynamically stable phases, with Kagomé-like and in-plane chemical ordering, and with incorporation of elements previously not known for MAX phases, including the common Y. We propose the structure to be monoclinic C2/c. As an extension of the work, we suggest a matching set of novel MXenes, from selective etching of the A-element. The demonstrated structural design on simultaneous two-dimensional (2D) and 3D atomic levels expands the property tuning potential of functional materials. PMID:28776034

Methods for Estimating Physicochemical Properties of Inorganic Chemicals of Environmental Concern. Volume 1

DTIC Science & Technology

1987-03-01

available. Kincaid et al. (221 provide an overview of the geochemical code history (up to 1983) in which they group models into four major families...plant. The *Ixample is adapted from a study by Morel ,’t al. 1291 for Los Angeles County. It is prv.ented in four ;ections: I ’ Problem statement, ý2...presents environmentally important priperty dJata for several groups of elements or compcui’ds. The data include, for Pxrimpie, precal- culated

Group typicality, group loyalty and cognitive development.

PubMed

Patterson, Meagan M

2014-09-01

Over the course of childhood, children's thinking about social groups changes in a variety of ways. Developmental Subjective Group Dynamics (DSGD) theory emphasizes children's understanding of the importance of conforming to group norms. Abrams et al.'s study, which uses DSGD theory as a framework, demonstrates the social cognitive skills underlying young elementary school children's thinking about group norms. Future research on children's thinking about groups and group norms should explore additional elements of this topic, including aspects of typicality beyond loyalty. © 2014 The British Psychological Society.

Cell-Sediment Separation and Elemental Stoichiometries in Extreme Environments

NASA Astrophysics Data System (ADS)

Neveu, M.; Poret-peterson, A. T.; Lee, Z. M.; Anbar, A. D.; Elser, J. J.

2012-12-01

Better understanding of the coupling of major biogeochemical cycles requires knowledge of the cellular elemental composition of key microbes. This is difficult in benthic sediments and mats, because of the contributions of non-living components. We are particularly interested in microbial extremophiles, and therefore sought to determine and interpret bulk and cellular elemental ratios in complex field-collected sediment samples from diverse hot spring ecosystems of Yellowstone National Park (YNP). These samples covered a broad range of temperature, pH, and chemical composition. We also sought to extend stoichiometric analysis to a broader suite of elements, including metals (Fe, Ni, Cu, Zn, Mo, etc.) of biological importance (Sterner and Elser, 2002). To overcome the challenge of rigorously isolating communities from their complex mineral matrices (Havig et al., 2011), we adapted a cell-sediment separation procedure from Amalfitano and Fazi (2008). The method involves chemical (use of a detergent and a chelating agent) and physical methods (stirring, gentle sonication, and gradient centrifugation) to break the microbe-mineral bonds. C and N elemental and isotopic abundances were determined by elemental analysis - isotope ratio - mass spectrometry (EA-IR-MS), while P, Na, Mg, Al, K, Ca, V, Cr, Fe, Co, Ni, Cu, Zn, and Mo contents were determined by inductively coupled plasma - mass spectrometry (ICP-MS). We sought to assess the existence of an "Extended Redfield Ratio" (ERR) for these microbes; that is, to establish the multi-element stoichiometric envelope within which extremophilic microbes must operate. Elemental and isotopic mass balance analyses of cultured E. coli before and after separation showed that our procedure preserved cellular C, N, P, Fe, and trace metal contents: neither loss of these elements (e.g., by cell lysis) nor contamination by reagents were observed. On the other hand, cation-forming elements (Na, Mg, K, Ca), were not conserved. Cell counting by epifluorescence microscopy indicated a cell recovery yield between 6 and 40% in field-collected samples (95% for cultured E. coli). Aluminum, assumed to be non-biological in origin, was used to estimate the extent of mineral contamination of isolated cell communities. These results show that our method is successful at separating microbial cells from sediment collected in extreme environments and preserving them for analysis of a broad suite of elements. Photosynthetic sites yielded much more cell material than hotter, chemosynthetic sites (Cox et al., 2011). We are currently measuring cellular elemental abundances and ratios in samples from relatively low-temperature (25 to 65°C), photosynthetic areas, spanning a wide range of pH (2 to 9.5) and composition. These measurements will be compared to existing datasets on the bulk sediment stoichiometry of these ecosystems, and to previous observations of cellular elemental composition. References: Redfield, A.C. (1934) In Daniel, R.J. [Ed.], James Johnstone Memorial Volume, pp. 176-192, Univ. Press Liverpool. Sterner, R.W., Elser, J.J. (2002) Ecological Stoichiometry Princeton Univ. Press, 441p. Havig, J.R., et al. (2011) JGR 116, G01005. Amalfitano, S., Fazi, S. (2008) J. of Microbiol. Methods 75, 237-243. Cox, A., et al. (2011) Chem. Geol. 280, 344-351.

Various soil amendments and environmental wastes affect the (im)mobilization and phytoavailability of potentially toxic elements in a sewage effluent irrigated sandy soil.

PubMed

Shaheen, Sabry M; Shams, Mohamed S; Khalifa, Mohamed R; El-Dali, Mohamed A; Rinklebe, Jörg

2017-08-01

Contamination of long-term sewage effluent irrigated soils by potentially toxic elements (PTEs) is a serious concern due to its high environmental and health risk. Our scientific hypothesis is that soil amendments can cause contradictory effects on the element mobilization and phytoavailability depending on the type of element and amendment. Therefore, we aimed to assess the impact of the application (1%) of several low cost amendments and environmental wastes on the (im)mobilization, availability, and uptake of Al, Cd, Cr, Cu, Fe, Mn, Ni, and Zn by sorghum (Sorghum bicolor) in a long term sewage effluent irrigated sandy soils collected from Egypt. The used materials include activated charcoal (AC), potassium humate (KH), phosphate rock (PR), phosphogypsum (PG), triple superphosphate (TSP), phosphoric acid (PA), sulfur (S), sugar beet factory lime (SBFL), cement bypass kiln dust (CBD), egg shell (ES), bone mill (BM), brick factory residual (BFR), ceramic powder (CP), and drinking water treatment residual (WTR). The mobilization and availability of the elements in the soil were extracted using NH 4 NO 3 and ammonium bicarbonate- diethylene triamine penta acetic acid (AB-DTPA), respectively. The above-ground biomass samples were analyzed for the elements studied. The results confirmed our hypothesis and concluded that although some amendments like S, PA, and TSP can be used for reducing the plant uptake of Al, Cr, and Fe, they might be used with KH for enhancing the phytoextraction of Cd, Cu, Mn, and Ni. Moreover, several wastes such as BFR and WTR might be used for enhancing the phytoextraction of Al, Cd, Cr, Cu, Fe, and Ni and reducing the uptake of Mn from the studied soil. Although SBFL decreased the plant uptake of Al, Fe, Mn, and Zn, it's increased the plant uptake of Cd, Cu, and Ni. Therefore, the amendments which reduce the plant uptake of an element might be suitable candidates for its immobilization, while the amendments which increase the plant uptake of an element might be used for enhancing its phytoextraction when using bioenergy crops like sorghum in similar contaminated sandy soils. The studied materials offered the potential for effective and low cost media for the treatment of PTEs contaminated sewage effluent irrigated sandy soils. These results should be verified in a field study. Copyright © 2017 Elsevier Inc. All rights reserved.

A high-pyrite semianthracite of Late Permian age in the Songzao Coalfield, southwestern China: Mineralogical and geochemical relations with underlying mafic tuffs

USGS Publications Warehouse

Dai, S.; Wang, X.; Chen, W.; Li, D.; Chou, C.-L.; Zhou, Y.; Zhu, Chen; Li, H.; Zhu, Xudong; Xing, Y.; Zhang, W.; Zou, J.

2010-01-01

The No. 12 Coal (Late Permian) in the Songzao Coalfield, Chongqing, southwestern China, is characteristically high in pyrite and some trace elements. It is uniquely deposited directly above mafic tuff beds. Samples of coal and tuffs have been studied for their mineralogy and geochemistry using inductively coupled plasma-mass spectrometry, X-ray fluorescence, plasma low-temperature ashing plus powder X-ray diffraction, and scanning electron microscopy equipped with energy-dispersive X-ray analysis.The results show that the minerals of the No. 12 Coal are mainly composed of pyrite, clay minerals (kaolinite, chamosite, and illite), ankerite, calcite, and trace amounts of quartz and boehmite. Kaolinite and boehmite were mainly derived from sediment source region of mafic tuffs. Chamosite was formed by the reaction of kaolinite with Fe-Mg-rich fluids during early diagenesis. The high pyrite (Sp,d=8.83%) in the coal was related to marine transgression over peat deposits and abundant Fe derived from the underlying mafic tuff bed. Ankerite and calcite were precipitated from epigenetic fluids.Chemical compositions of incompatible elements indicate that the tuffs were derived from enriched mantle and the source magmas had an alkali-basalt character. Compared to other coals from the Songzao Coalfield and common Chinese coals, the No. 12 Coal has a lower SiO2/Al2O3 (1.13) but a higher Al2O3/Na2O (80.1) value and is significantly enriched in trace elements including Sc (13.5??g/g), V (121??g/g), Cr (33.6??g/g), Co (27.2??g/g), Ni (83.5??g/g), Cu (48.5??g/g), Ga (17.3??g/g), Y (68.3??g/g), Zr (444??g/g), Nb (23.8??g/g), and REE (392??g/g on average). Above mineralogical compositions, as well as similar ratios of selected elements (e.g., SiO2/Al2O3 and Al2O3/Na2O) and similar distribution patterns of incompatible elements (e.g., the mantle-normalized diagram for incompatible elements and chondrite-normalized diagram for rare earth elements) of coal and tuff, indicated that enriched trace elements above were largely derived from mafic tuffs, in addition to a minor amount from the Kandian Oldland. ?? 2010 Elsevier B.V.

High H2O/Ce of K-rich MORB from Lena Trough and Gakkel Ridge, Arctic Ocean

NASA Astrophysics Data System (ADS)

Snow, J. E.; Feig, S. T.

2014-12-01

Lena Trough in the Arctic ocean is the oblique spreading continuation of Gakkel Ridge through the Fram Strait (eg Snow et al. 2011). Extreme trace element and isotopic compositions seen in Lena Trough basalt appear to be the enriched end member dominating the geochemistry of the Western Volcanic Zone of the Western Gakkel Ridge as traced by Pb isotopes, K2O/TiO2, Ba/Nb and other isotopic, major and trace element indicators of mixing (Nauret et al., 2011). This is in contrast to neighboring Gakkel Ridge which has been spreading for 50-60 million years. Basalts from Lena Trough also show a pure MORB noble gas signature (Nauret et al., 2010) and peridotites show no evidence of ancient components in their Os isotopes (Lassiter, et al., in press). The major and trace element compositions of the basalts, however are very distinct from MORB, being far more potassic than all but a single locality on the SW Indian Ridge. We determined H2O and trace element composiitions of a suite of 17 basalt glasses from the Central Lena Trough (CLT) and the Gakkel Western Volcanic Zone, including many of those previously analyzed by Nauret et al. (2012). The Western Gakkel glasses have high H2O/Ce for MORB (>300) suggesting a water rich source consistent with the idea that the northernmost Atlantic mantle is enriched in water (Michael et al., 1995). They are within the range of Eastern Gakkel host glasses determined by Wanless et al, 2013. The Lena Trough (CLT) glasses are very rich in water for MORB (>1% H2O) and are among the highest H2O/Ce (>400) ever measured in MORB aside from melt inclusions in olivine. Mantle melting dynamics and melt evolution cannot account for the H2O/Ce variations in MORB, as these elements have similar behavior during melting and crustal evolution. Interestingly, the H2O/K2O ratios in the basalts are only around 1. This is because the K2O levels in the CLT glasses are very high as well relative to REE. The absolutely linear relationship between H2O and K2O/TiO2 in Lena and Gakkel basalts shows that water systematics in these rocks are completely governed by source composition, with little or no modification by mantle melting dynamics or crystal fractionation. The geochemical influence of the WVZ enriched mantle source declines with distance from Lena Trough along Gakkel Ridge.

Choosing a therapy electron accelerator target.

PubMed

Hutcheon, R M; Schriber, S O; Funk, L W; Sherman, N K

1979-01-01

Angular distributions of photon depth dose produced by 25-MeV electrons incident on several fully stopping single-element targets (C, Al, Cu, Mo, Ta, Pb) and two composite layered targets (Ni-Al, W-Al) were studied. Depth-dose curves measured using TLD-700 (thermoluminescent dosimeter) chips embedded in lucite phantoms. Several useful therapy electron accelerator design curves were determined, including relative flattener thickness as a function of target atomic number, "effective" bremsstrahlung endpoint energy or beam "hardness" as a function of target atomic number and photon emission angle, and estimates of shielding thickness as a function of angle required to reduce the radiation outside the treatment cone to required levels.

In Situ Characterization of Boehmite Particles in Water Using Liquid SEM.

PubMed

Yao, Juan; Arey, Bruce W; Yang, Li; Zhang, Fei; Komorek, Rachel; Chun, Jaehun; Yu, Xiao-Ying

2017-09-27

In situ imaging and elemental analysis of boehmite (AlOOH) particles in water is realized using the System for Analysis at the Liquid Vacuum Interface (SALVI) and Scanning Electron Microscopy (SEM). This paper describes the method and key steps in integrating the vacuum compatible SAVLI to SEM and obtaining secondary electron (SE) images of particles in liquid in high vacuum. Energy dispersive x-ray spectroscopy (EDX) is used to obtain elemental analysis of particles in liquid and control samples including deionized (DI) water only and an empty channel as well. Synthesized boehmite (AlOOH) particles suspended in liquid are used as a model in the liquid SEM illustration. The results demonstrate that the particles can be imaged in the SE mode with good resolution (i.e., 400 nm). The AlOOH EDX spectrum shows significant signal from the aluminum (Al) when compared with the DI water and the empty channel control. In situ liquid SEM is a powerful technique to study particles in liquid with many exciting applications. This procedure aims to provide technical know-how in order to conduct liquid SEM imaging and EDX analysis using SALVI and to reduce potential pitfalls when using this approach.

Searching the Sinus Amoris: Using profiles of geological units, impact and volcanic features to characterize a major terrane interface on the Moon

NASA Technical Reports Server (NTRS)

Clark, P.; Joerg, S.; Dehon, R.

1994-01-01

Geochemical profiles of surface units, impact, and volcanic features are studied in detail to determine the underlying structure in an area of extensive mare/highland interface, Sinus Amoris. This study region includes and surrounds the northeastern embayment of Mare Tranquillitatis. The concentrations of two major rock-forming elements (Mg and Al), which were derived from the Apollo 15 orbital geochemical measurements, were used in this study. Mapped units and deposits associated with craters in the northwestern part of the region tend to have correlated low Mg and Al concentrations, indicating the presence of Potassium (K)-Rare Earth Elements (REE)-Phosphorus (P) (KREEP)-enriched basalt. Found along the northeastern rim of Tranquillitatis were areas with correlated high Mg and Al concentration, indicating the presence of troctolite. Distinctive west/east and north/south trends were observed in the concentrations of Mg and Al, and, by implication, in the distribution of major rock components on the surface. Evidence for a systematic geochemical transition in highland or basin-forming units may be observed here in the form of distinctive differences in chemistry in otherwise similar units in the western and eastern portions of the study region.

Visualizing trace element distribution in quartz using cathodoluminescence, electron microprobe, and laser ablation-inductively coupled plasma-mass spectrometry

USGS Publications Warehouse

Rusk, Brian; Koenig, Alan; Lowers, Heather

2011-01-01

Cathodoluminescent (CL) textures in quartz reveal successive histories of the physical and chemical fluctuations that accompany crystal growth. Such CL textures reflect trace element concentration variations that can be mapped by electron microprobe or laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Trace element maps in hydrothermal quartz from four different ore deposit types (Carlin-type Au, epithermal Ag, porphyry-Cu, and MVT Pb-Zn) reveal correlations among trace elements and between trace element concentrations and CL textures. The distributions of trace elements reflect variations in the physical and chemical conditions of quartz precipitation. These maps show that Al is the most abundant trace element in hydrothermal quartz. In crystals grown at temperatures below 300 °C, Al concentrations may vary by up to two orders of magnitude between adjacent growth zones, with no evidence for diffusion. The monovalent cations Li, Na, and K, where detectable, always correlate with Al, with Li being the most abundant of the three. In most samples, Al is more abundant than the combined total of the monovalent cations; however, in the MVT sample, molar Al/Li ratios are ~0.8. Antimony is present in concentrations up to ~120 ppm in epithermal quartz (~200–300 °C), but is not detectable in MVT, Carlin, or porphyry-Cu quartz. Concentrations of Sb do not correlate consistently with those of other trace elements or with CL textures. Titanium is only abundant enough to be mapped in quartz from porphyry-type ore deposits that precipitate at temperatures above ~400 °C. In such quartz, Ti concentration correlates positively with CL intensity, suggesting a causative relationship. In contrast, in quartz from other deposit types, there is no consistent correlation between concentrations of any trace element and CL intensity fluctuations.

Microwave digestion for the quantification of inorganic elements in coal and coal ash using ICP-OES.

PubMed

Low, Fiona; Zhang, Lian

2012-11-15

In this paper, microwave digestion conditions have been optimised to achieve complete recoveries for the ash-forming inorganic elements in coal and coal combustion fly ash, during the analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES). The elements analysed include six major (Al, Ca, Fe, K, Mg and Na) and twelve trace (As, Ba, Be, Co, Cr, Cu, Li, Mn, Ni, Pb, Sr and V). Seven reference samples have been tested, including two standard coal references, SRM1632c and SARM19, their corresponding high-temperature ashes (HTAs), and three coal fly ash references, SRM1633c, SRM2690 and BCR38. The recoveries of individual elements in these samples have been examined intensively, as a function of the amount of hydrofluoric acid (HF, 0-2.0 ml), microwave power (900 W vs. 1200 W) and sample mass (0.05 g vs. 0.1 g). As have been confirmed, the recoveries of these individual elements varied significantly with the microwave digestion condition, elemental type and sample property. For the coal references and their HTAs, the use of HF can be ruled out for most of the elements, except K associated with feldspar, Pb and V. In particular, the recovery of Pb in coal is highly sample-specific and thus unpredictable. The majority of elements in fly ash references require the use of 0.1-0.2 ml HF for a complete recovery. Al in fly ash is the only exceptional element which gave incomplete recoveries throughout, suggesting the use of a complementary technique for its quantification. As has proven to be the only element inconsequential of sample type and digestion conditions, achieving complete recoveries for all cases. On the power parameter, using a higher power such as 1200 W is critical, which has proved to be an ultimatum for the recovery of certain elements, especially in fly ash. Halving sample mass from 0.1 g to 0.05 g was also found to be insignificant. Copyright © 2012 Elsevier B.V. All rights reserved.

PATHFINDER ATOMIC POWER PLANT TECHNICAL PROGRESS REPORT FOR JULY 1, 1959- SEPTEMBER 30, 1959

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1960-10-31

ABS>Fuel Element Research and Development. Dynamic and static corrosion tests on 8001 Al were completed. Annealmmmg of 1100 cladding on 5083 and M400 cladding on X2219 were tested at 500 deg C, and investigation continued on producing X8101 Al alloy cladding in tube plates by extrusion. Boiler fuel element capsule irradiation tests and subassembly tests are described Heat transfer loop studies and fuel fabrication for the critical facility are reported. Boiler fuel element mechanical design and testing progress is desc ribed. and the superheater fuel element temperature evaluating routine is discussed. Low- enrichment superheater fuel element development included design studiesmore » and stainless steel powder and UO/sub 2/ powder fabrication studies Reactor Mechanical Studies. Research is reported on vessel and structure design, fabrication, and testing, recirculation system design, steam separator tests, and control rod studies. Nuclear Analysis. Reactor physics studies are reported on nuclear constants, baffle plate analysis, comparison of core representations, delayed neutron fraction. and shielding analysis of the reactor building. Reactor and system dynamics and critical experiments were also studied. Chemistry. Progress is reported on recombiner. radioactive gas removal and storage, ion exchanger and radiochemical processing. (For preceding period see ACNP-5915.) (T.R.H.)« less

Geochemistry of Woranso-Mille Pliocene basalts from west-central Afar, Ethiopia: Implications for mantle source characteristics and rift evolution

NASA Astrophysics Data System (ADS)

Alene, Mulugeta; Hart, William K.; Saylor, Beverly Z.; Deino, Alan; Mertzman, Stanley; Haile-Selassie, Yohannes; Gibert, Luis B.

2017-06-01

The Woranso-Mille (WORMIL) area in the west-central Afar, Ethiopia, contains several Pliocene basalt flows, tuffs, and fossiliferous volcaniclastic beds. We present whole-rock major- and trace-element data including REE, and Sr-Nd-Pb isotope ratios from these basalts to characterize the geochemistry, constrain petrogenetic processes, and infer mantle sources. Six basalt groups are distinguished stratigraphically and geochemically within the interval from 3.8 to 3 Ma. The elemental and isotopic data show intra- and inter-group variations derived primarily from source heterogeneity and polybaric crystallization ± crustal inputs. The combined Sr-Nd-Pb isotope data indicate the involvement of three main reservoirs: the Afar plume, depleted mantle, and enriched continental lithosphere (mantle ± crust). Trace element patterns and ratios further indicate the basalts were generated from spinel-dominated shallow melting, consistent with significantly thinned Pliocene lithosphere in western Afar. The on-land continuation of the Aden rift into western Afar during the Pliocene is reexamined in the context of the new geochemistry and age constraints of the WORMIL basalts. The new data reinforce previous interpretations that progressive rifting and transformation of the continental lithosphere to oceanic lithosphere allows for increasing asthenospheric inputs through time as the continental lithosphere is thinned. Accepted trace element values for BHVO-2 are those recently recommended by Jochum et al. (2016) rounded to provide the same significant figures as the data. Ternary model after Schilling et al. (1992); Endmembers from Rooney et al. (2012).

Trace element mobility at the slab-mantle interface: constraints from "hybrid

NASA Astrophysics Data System (ADS)

Marocchi, M.; Tropper, P.; Mair, V.; Bargossi, G. M.; Hermann, J.

2009-04-01

Subduction mélanges and hybrid rocks are considered, together with mafic rocks, metasediments and serpentinite as an important volatile-bearing portion of subducting slabs (cf. Spandler et al., 2008 and references therein; Miller et al., 2009). In particular, metasomatic rocks occurring in exhumed HP mélanges have recently attracted growing interest for two main reasons: i) metasomatic rocks forming at the interface between ultramafic and crustal rocks of subducting slabs constitute new bulk compositions which can affect the redistribution of major and trace elements and modify the composition of slab fluids moving to the mantle wedge and ii) these mineral assemblages, consisting mainly of hydrous phases can potentially store and transport water at great depth in subduction zones. Ultramafic rocks belonging to the Hochwart peridotite (Ulten Zone, central-eastern Italian Alps) preserve a series of metasomatic mineral zones generated by infiltration of hydrous fluids/melts, which occurred at the gneiss-peridotite interface (Tumiati et al., 2007; Marocchi et al., 2009). The peridotite body of Mt. Hochwart represents an almost unique occurrence where subduction-related mantle metasomatism can be studied on an outcrop scale. The ultramafic body consists of metaperidotites exposed as a hectometre-size lens along a steep gully, associated to monomineralic zones that developed at the contact between the peridotite body and the garnet-bearing gneiss country rocks. The formation of the metasomatic zones composed exclusively of hydrous phases involved extensive H2O-metasomatism as already documented for the Ulten peridotites (Scambelluri et al., 2006; Marocchi et al., 2007). Whole-rock geochemistry and trace element composition of hydrous phases (phlogopite and amphibole) in different metasomatic zones indicate mobility of many elements, including elements such as Ta, which are considered to have scarce mobility in fluids. Trace element composition of accessory minerals in the phlogopite-rich zone suggests that the trace element signature of subduction zone fluids may be fractionated in this zone. The progressive depletion in some trace elements (LREE and LILE) and enrichment in Li from the gneiss towards the peridotite suggests a strong influence of bulk composition on the trace element budget of hydrous minerals. Since these metasomatic zones can be representative of the processes occurring at the slab-mantle interface, we can infer that metasomatic reactions between slab-derived fluids and ultramafic mantle wedge will follow a specific series of reactions and create mineral zones similar to those observed in this study. Despite the mobility of many elements, in the trace element profiles for amphibole and phlogopite across the different zones, we observe a rapid decrease even of the "fluid mobile" element contents within the reaction zone. With the exception of Li, we assist to an abrupt decrease of most of trace element concentrations going towards the peridotite side contact. Thus, according to the present study, it is not likely that the "crustal trace element signature" (i.e. LILE and LREE-enriched) could be able to travel far into the mantle. Our results further favour the evidence that the primary composition of subduction zone fluids reaching the source region of arc magmas is substantially modified by metasomatic reactions occurring in the mantle wedge. Furthermore, we underline that metasomatic rocks such as those observed at Mt. Hochwart are potentially able to transport H2O and other trace elements to greater depths in subduction zones. References: Marocchi M, Hermann J, Morten L (2007)-Lithos 99: 85-104. Marocchi M, Mair V, Tropper P, Bargossi GM (2009)-Mineral Petrol, in press Miller DP, Marschall RH, Schumacher JC (2009)- Lithos 107: 53-67. Scambelluri M, Hermann J, Morten L, Rampone E (2006)- Contrib Mineral Petrol 151:372-394. Spandler CJ, Hermann J, Faure K, Mavrogenes JA, Arculus RJ (2008)- Contrib Mineral Petrol 155: 181-198. Tumiati S, Godard G, Martin S, Klőtzli U, Monticelli D (2007)- Lithos 94: 148-167.

Finite element analysis of hypervelocity impact behaviour of CFRP-Al/HC sandwich panel

NASA Astrophysics Data System (ADS)

Phadnis, Vaibhav A.; Silberschmidt, Vadim V.

2015-09-01

The mechanical response of CFRP-Al/HC (carbon fibre-reinforced/epoxy composite face sheets with Al honeycomb core) sandwich panels to hyper-velocity impact (up to 1 km/s) is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by mean of a user-defined material model (VUMAT) employing a combination of Hashin and Puck criteria, delamination modelled using cohesive-zone elements. The damaged Al/HC core is assessed on the basis of a Johnson Cook dynamic failure model while its hydrodynamic response is captured using the Mie-Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing HC core.

Research on the relationship between the elements and pharmacological activities in velvet antler using factor analysis and cluster analysis

NASA Astrophysics Data System (ADS)

Zhou, Libing

2017-04-01

Velvet antler has certain effect on improving the body's immune cells and the regulation of immune system function, nervous system, anti-stress, anti-aging and osteoporosis. It has medicinal applications to treat a wide range of diseases such as tissue wound healing, anti-tumor, cardiovascular disease, et al. Therefore, the research on the relationship between pharmacological activities and elements in velvet antler is of great significance. The objective of this study was to comprehensively evaluate 15 kinds of elements in different varieties of velvet antlers and study on the relationship between the elements and traditional Chinese medicine efficacy for the human. The factor analysis and the factor cluster analysis methods were used to analyze the data of elements in the sika velvet antler, cervus elaphus linnaeus, flower horse hybrid velvet antler, apiti (elk) velvet antler, male reindeer velvet antler and find out the relationship between 15 kinds of elements including Ca, P, Mg, Na, K, Fe, Cu, Mn, Al, Ba, Co, Sr, Cr, Zn and Ni. Combining with MATLAB2010 and SPSS software, the chemometrics methods were made on the relationship between the elements in velvet antler and the pharmacological activities. The first commonality factor F1 had greater load on the indexes of Ca, P, Mg, Co, Sr and Ni, and the second commonality factor F2 had greater load on the indexes of K, Mn, Zn and Cr, and the third commonality factor F3 had greater load on the indexes of Na, Cu and Ba, and the fourth commonality factor F4 had greater load on the indexes of Fe and Al. 15 kinds of elements in velvet antler in the order were elk velvet antler>flower horse hybrid velvet antler>cervus elaphus linnaeus>sika velvet antler>male reindeer velvet antler. Based on the factor analysis and the factor cluster analysis, a model for evaluating traditional Chinese medicine quality was constructed. These studies provide the scientific base and theoretical foundation for the future large-scale rational relation development of velvet antler resources as well as the relationship between the elements and traditional Chinese medicine efficacy for the human.

Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA

NASA Astrophysics Data System (ADS)

Weisend, R.; Morton, P. L.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Phytoplankton in oligotrophic marine deserts depend on remote sources to supply trace nutrients. To examine these sources, marine particulate matter samples from the central North Pacific (Station ALOHA) were collected during the July-August 2012 HOE-DYLAN cruises and analyzed for a suite of trace (e.g., Fe, Mn) and major (e.g. Al, P) elements. Daily surface SPM samples were examined for evidence of atmospheric deposition and biological uptake, while five vertical profiles were examined for evidence of surface vertical export and subsurface horizontal transport from nearby sources (e.g., margin sediments, hydrothermal plumes). Maxima in surface particulate P (a biological tracer) corresponded with a diatom bloom, and surprisingly also coincided with maxima in particulate Al (typically a tracer for lithogenic inputs). The surface particulate Al distributions likely result from the adsorption of dissolved Al onto diatom silica frustules, not from atmospheric dust deposition. In addition, a subsurface maximum in particulate Al and P was observed four days later at 75m, possibly resulting from vertical export of the surface diatom bloom. The distributions of other bioactive trace elements (e.g. Cd, Co, Cu) will be presented in the context of the diatom bloom and other biological, chemical and physical features. A second, complementary poster is also being presented which examines the cycling of trace elements in lithogenic particles (Morton et al., "Trace Element Cycling in Lithogenic Particles at Station ALOHA").

Emergence of Habitable Environments in Icy World Interiors

NASA Astrophysics Data System (ADS)

Neveu, Marc

2016-07-01

Finding habitable worlds is a key driver of solar system exploration. Many solar system missions seek environments providing liquid water, energy, and nutrients, the three ingredients necessary to sustain life [1]. Such environments include hydrothermal systems, spatially confined systems where hot aqueous fluid circulates through rock by convection. Hydrothermal activity may be widespread in the solar system. Most solar system worlds larger than 200 km in radius are icy moons and dwarf planets, likely composed of an icy, cometary mantle surrounding a rocky, chondritic core [2]. By improving an icy world evolution code [3] to include the effects of core fracturing and hydrothermal circulation, I show that several icy moons and dwarf planets likely have undergone extensive water-rock interaction [4,5]. This supports observations of aqueous products on their surfaces [6,7]. I simulated the alteration of chondritic rock [8] by pure water or fluid of cometary composition [9] to show that aqueous alteration feeds back on geophysical evolution: it modifies the fluid antifreeze content, affecting its persistence over geological timescales; and the distribution of radionuclides, whose decay is a chief heat source on dwarf planets [10]. Hydrothermal circulation also efficiently transports heat from the core into the ocean, thereby increasing ocean persistence [4]. Thus, these coupled geophysical-geochemical models provide a comprehensive picture of icy world evolution and the emergence of liquid environments in chemical disequilibrium with underlying rock in their interiors. Habitable settings also require a suitable supply of bioessential elements; but what constitutes "suitable"? I sought to quantify the bulk elemental composition of hydrothermal microbial communities, collected in hot spring sediments and mats at Yellowstone National Park, USA. To do so, one must minimize the contribution of non-biological material to the samples analyzed. This was achieved using a separation method that takes advantage of the density contrast between cells and sediment and preserves cellular elemental contents [11]. Using this method, I showed that in spite of the tremendous physical, chemical, and taxonomic diversity of Yellowstone hot springs, the composition of microorganisms there is surprisingly ordinary [12]. This suggests the existence of a stoichiometric envelope common to all life as we know it. Thus, future planetary investigations could use elemental fingerprints to assess the astrobiological potential of hydrothermal settings beyond Earth. References: [1] US National Research Council (2011)Vision & Voyages in the Decade 2013-2022. [2] Hussmann et al. (2006) Icarus 185, 258-273. [3] Desch et al. (2009) Icarus 202, 694-714. [4] Neveu et al. (2015) JGR 120, 123-154. [5] Neveu & Rhoden, in prep. [6] De Sanctis et al. (2015) Nature 528, 241-244. [7] Hsu et al. (2015) Nature 519, 207-210. [8] Wasson & Kallemeyn (1988) Phil Trans R Soc London A 325, 535-544. [9] Mumma & Charnley (2011) Annu Rev Astron Astrophys 49, 471. [10] Neveu et al., in revision. [11] Neveu et al. (2014) Limn Oceanogr 12, 519-529. [12] Neveu et al. (2016) Geobiology 14, 33-53.

Interdiffusion behaviors in doped molybdenum uranium and aluminum or aluminum silicon dispersion fuels: Effects of the microstructure

NASA Astrophysics Data System (ADS)

Allenou, J.; Tougait, O.; Pasturel, M.; Iltis, X.; Charollais, F.; Anselmet, M. C.; Lemoine, P.

2011-09-01

Si addition to Al is considered as a promising route to reduce (U,Mo)-Al interaction kinetics, due to its accumulation in the interaction layer, yielding the formation of silicide phases. The (U,Mo) alloy microstructure, and especially its homogenization state, could play a role on this accumulation process. The addition of a third element in γ(U,Mo) could also influence diffusion mechanisms of Al and Si. These two parameters were studied by means of diffusion couple experiments by joining γU based alloys with Al and (Al,Si) alloy. Chemical elements X added into γ(U,Mo) were thoroughly chosen on the following criteria: (i) the potential solubility of the alloying element into the γ(U,Mo) matrix, (ii) its capability to form the ternary aluminides based on the CeCr 2Al 20 and Ho 6Mo 4Al 43 - types, and (iii) the feasibility to control the microstructure of the alloys. On this basis, a test matrix is defined. It concerns γ(U80,Mo15,X5) alloys (in at.%) with X = Y, Cu, Zr, Ti or Cr. These alloys were homogenized and coupled with Al or (Al,Si) alloy. Results evidenced, first, the importance of the state of homogenization of the γ(U,Mo) binary alloy on interaction processes with (Al,Si) alloy, and the benefit on the diffusion of Si through the interaction layer, as observed on the elementary concentration profiles, when the third element X has some solubility into γ(U,Mo) alloy.

Characterizing coal beds in western Kentucky with the Al-La-Sc coherent triad

USGS Publications Warehouse

Chyi, L.L.; Medlin, J.H.

1996-01-01

Cyclic sedimentation and lateral facies changes make coal bed correlations inconclusive and difficult. This uncertainty can be further complicated if a coal basin has been structurally deformed. Coal macerals can be studied to indicate the nature and degree of coalification. Their use in coal bed correlation, however, is limited. Most of the trace elements and their ratios that have been studied show significant within-bed lateral and stratigraphic variations, and thus are not effective in correlating coal beds regionally. Geochemically coherent groups of elements, such as rare earth elements (REE) and platinum group elements (PGE), appear to be highly differentiated in coal-forming environments. Geochemical coherent elemental triads appear to be useful for coal bed identification or fingerprinting. The best triad which was demonstrated to be effective in coal bed characterization in western Kentucky, is that of Al, La and Sc. These three elements are highly correlated with one another and they can be determined accurately and simultaneously with instrumental neutron activation analysis (INAA). The elemental triad Al-La-Sc is used to identify and fingerprint three key coal beds in western Kentucky: the Springfield (western Kentucky No. 9), the Davis (western Kentucky No. 6), and the Mining City and Dawson Springs are both considered to be the No. 4 coal bed in western Kentucky). Four distinct groupings can be recognized by use of the Al-La-Sc triad. The Dawson Springs coals have the highest Al/(La + Sc) ratios, followed by the Springfield, the Davis and the Mining City. The Mining City coal bed generally has the highest La/Sc ratio. However, the Dawson Springs is not correlated with the Mining City using the triad analysis, even though they have reportedly similar stratigraphic positions in the western Kentucky coal basin. The Al-La-Sc triad appears to be effective in discriminating between the Springfield and the Davis coal beds throughout the entire Illinois Basin. Furthermore, the range of concentration variation of the AL-La-Sc triad suggests individual groupings of the No. 4 coal in western Kentucky. In addition to characterizing these coal beds, the Al-La-Sc triad may be used to confirm stratigraphic correlations.

DIYA: A Bacterial Annotation Pipeline for any Genomics Lab

DTIC Science & Technology

2009-02-12

make more modules available. Functions we are looking to add to the DIYA pipeline include software for detection of prophages, CRISPR elements (Sorek...R. et al. (2008) CRISPR –a widespread system that provides acquired resistance against phages in bacteria and archaea. Nat. Rev. Microbiol., 6, 181

Transmission of atmospherically derived trace elements through an undeveloped, forested Maryland watershed

USGS Publications Warehouse

Scudlark, J.R.; Rice, Karen C.; Conko, Kathryn M.; Bricker, Owen P.; Church, T.M.

2005-01-01

The transmission of atmospherically derived trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn) was evaluated in a small, undeveloped, forested watershed located in north-central Maryland. Atmospheric input was determined for wet-only and vegetative throughfall components. Annual throughfall fluxes were significantly enriched over incident precipitation for most elements, although some elements exhibited evidence of canopy release (Mn) or preferential uptake (As, Cr, and Se). Stream export was gauged based on systematic sampling under varied flow regimes. Particle loading appears to contribute significantly to watershed export (> 10%) for only As, Pb, and Fe, and then only during large precipitation/runoff events. The degree of watershed transmission for each trace element was evaluated based on a comparison of total, net atmospheric input (throughfall) to stream export over an annual hydrologic cycle. This comparison indicates that the atmospheric input of some elements (Al, Cd, Ni, Zn) is effectively transmitted through the watershed, but other elements (Pb, As, Se, Fe, Cr, Cu) appear to be strongly sequestered, in the respective orders noted. Results suggest that precipitation and subsequent soil pH are the primary factors that determine the mobility of sequestered trace element phases.To further resolve primary atmospheric and secondary weathering components, the geochemical model NETPATH was applied. Results indicate that minerals dissolved include chlorite, plagioclase feldspar, epidote, and potassium feldspar; phases formed were kaolinite, pyrite, and silica. The model also indicates that weathering processes contribute negligible amounts of trace elements to stream export, indicative of the unreactive orthoquartzite bedrock lithology underlying the watershed. Thus, the stream export of trace elements primarily reflects atmospheric deposition to the local watershed.

Alumina forming iron base superalloy

DOEpatents

Yamamoto, Yukinori; Muralidharan, Govindarajan; Brady, Michael P.

2014-08-26

An austenitic stainless steel alloy, consists essentially of, in weight percent 2.5 to 4 Al; 25 to 35 Ni; 12 to 19 Cr; at least 1, up to 4 total of at least one element selected from the group consisting of Nb and Ta; 0.5 to 3 Ti; less than 0.5 V; 0.1 to 1 of at least on element selected from the group consisting of Zr and Hf; 0.03 to 0.2 C; 0.005 to 0.1 B; and base Fe. The weight percent Fe is greater than the weight percent Ni. The alloy forms an external continuous scale including alumina, and contains coherent precipitates of .gamma.'-Ni.sub.3Al, and a stable essentially single phase FCC austenitic matrix microstructure. The austenitic matrix is essentially delta-ferrite-free and essentially BCC-phase-free.

The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of 26Al [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of 26Al.

DOE PAGES

Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; ...

2012-09-13

Most accelerator mass spectrometry measurements of 26Al utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense 26AlO- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of twenty. This suppression was insufficient to enable themore » use of 26AlO-, however further refinement of our system may permit its use in the future.« less

Effect of truncated cone roughness element density on hydrodynamic drag

NASA Astrophysics Data System (ADS)

Womack, Kristofer; Schultz, Michael; Meneveau, Charles

2017-11-01

An experimental study was conducted on rough-wall, turbulent boundary layer flow with roughness elements whose idealized shape model barnacles that cause hydrodynamic drag in many applications. Varying planform densities of truncated cone roughness elements were investigated. Element densities studied ranged from 10% to 79%. Detailed turbulent boundary layer velocity statistics were recorded with a two-component LDV system on a three-axis traverse. Hydrodynamic roughness length (z0) and skin-friction coefficient (Cf) were determined and compared with the estimates from existing roughness element drag prediction models including Macdonald et al. (1998) and other recent models. The roughness elements used in this work model idealized barnacles, so implications of this data set for ship powering are considered. This research was supported by the Office of Naval Research and by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

Mapping Fifteen Trace Elements in Human Seminal Plasma and Sperm DNA.

PubMed

Ali, Sazan; Chaspoul, Florence; Anderson, Loundou; Bergé-Lefranc, David; Achard, Vincent; Perrin, Jeanne; Gallice, Philippe; Guichaoua, Marie

2017-02-01

Studies suggest a relationship between semen quality and the concentration of trace elements in serum or seminal plasma. However, trace elements may be linked to DNA and capable of altering the gene expression patterns. Thus, trace element interactions with DNA may contribute to the mechanisms for a trans-generational reproductive effect. We developed an analytical method to determine the amount of trace elements bound to the sperm DNA, and to estimate their affinity for the sperm DNA by the ratio: R = Log [metal concentration in the sperm DNA/metal concentration in seminal plasma]. We then analyzed the concentrations of 15 trace elements (Al, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Ti, V, Zn, As, Sb, and Se) in the seminal plasma and the sperm DNA in 64 normal and 30 abnormal semen specimens with Inductively Coupled Plasma/Mass Spectrometry (ICP-MS). This study showed all trace elements were detected in the seminal plasma and only metals were detected in the sperm DNA. There was no correlation between the metals' concentrations in the seminal plasma and the sperm DNA. Al had the highest affinity for DNA followed by Pb and Cd. This strong affinity is consistent with the known mutagenic effects of these metals. The lowest affinity was observed for Zn and Ti. We observed a significant increase of Al linked to the sperm DNA of patients with oligozoospermia and teratozoospermia. Al's reproductive toxicity might be due to Al linked to DNA, by altering spermatogenesis and expression patterns of genes involved in the function of reproduction.

High-resolution mapping of elemental abundances of the lunar regolith

NASA Astrophysics Data System (ADS)

Wöhler, Christian; Berezhnoy, Alexey; Evans, Richard

Many attempts have been made to derive elemental abundances of the lunar surface from mul-tispectral images (cf. e.g. [1]). The gamma ray spectrometer on board the Lunar Prospector spacecraft (LP GRS) provided the first "direct" global measurements of lunar elemental abun-dances including Fe, Th (15 km surface resolution), Ti, K, Sm (60 km), Al, O, Si, Mg, Ca, and U (150 km). In this study we rely on the elemental abundance estimation method intro-duced in [2], which is based on spectral features derived from the Clementine UVVIS+NIR data set and estimates the abundances of Ca, Al, Fe, Mg, Ti, and O by applying a second order polynomial regression model with the corresponding LP GRS abundances as "ground truth". The regarded spectral features are the continuum slope, the FWHM of the ferrous absorption trough near 1000 nm after continuum division, and the absorption wavelengths and relative absorption depths (cf. [2,3] for details). A petrographic analysis is performed based on the abundances of the key elements Al, Fe, and Mg [4]. The relative abundances of the endmem-bers mare basalt, Mg-rich rock, and ferroan anorthosite are estimated using Fe-Mg and Al-Mg diagrams, where the endmember compositions are determined based on the three-endmember plane fitted in Al-Fe-Mg space to the elemental abundances at 150 km resolution obtained with the regression model. The root-mean-square deviation from the three-endmember plane is only 0.3 wt percent. Our petrographic map shows Mg-rich rocks in the Mare Frigoris region, on the edges of large maria, in the South Pole Aitken basin, and in some cryptomaria such as the Schiller-Schickard basin. The presence of Mg-rich rocks in Mare Frigoris explains the Fe and Ti depletion discussed in [5]. Furthermore, our analysis confirms that the basalts of eastern mare Frigoris have an atypically high Al content [6]. The region south of Lichtenberg and around Seleucus and Briggs in northwestern Oceanus Procellarum is characterised by comparably large deviations from the three-endmember plane in Al-Fe-Mg space of 1 wt percent and more. These anomalous basalts have low ages of 1.7-2.8 Ga [7]. They are characterised by secondary absorption features near 1100 nm and high 2000/1500 spectral ratios, indicating a high olivine content. Anomalous material in lunar craters is generally interpreted as being excavated during crater formation from the lower lunar crust or upper mantle (cf. e.g. [8]). For the highland crater Tycho, our method reveals mafic units in the northern crater wall and in the central peaks and Mg-rich rock in the southwestern crater wall and distributed throughout the crater floor. This material is interpreted in [9] as anorthositic gabbro with a low Fe content and a mafic mineral assemblage dominated by high-Ca pyroxene. Our petrographic map of Copernicus shows the central peaks as small regions composed of the mare basalt endmember (interpreted as gabbroic material) with admixed troctolite (western peak) and mainly troctolite (eastern peak), respectively [8]. For the central peaks of the crater Bullialdus, our technique clearly reveals the Mg-rich rock component, which is interpreted as norite in [10]. We present very high resolution petrographic maps derived from newly released Selene multi-spectral data of the central peaks of Copernicus and Bullialdus. For the pyroclastic deposits (LPDs) on the floor of Alphonsus, our technique indicates high Mg/Al ratios between 1.4 (eastern LPDs) and 2.5 (western LPD) [11]. The secondary absorption near 1100 nm and the high 2000/1500 ratio suggest the presence of a major olivine component. As a general result, we show that our regression-based elemental abundance estimation method allows the detection of the main lunar terrain classes and rock types on small spatial scales based on multispectral imagery in the visible and near-infrared domain. [1] Lucey et al. (2000), JGR 105(E8), 20297-20306. [2] Wühler et al. (2009), EPSC 2009, 263. [3] Evans et al. (2009) LPSC XXXX, 1093. [4] Berezhnoy et al. (2005), PSS 53, 1097-1108. [5] Taylor et al. (1996), LPSC XXVII, 1317-1318. [6] Kramer et al. (2009), LPSC XXXX, 2369. [7] Hiesinger et al. (2003), JGR 108(E7), 5065-5091. [8] Pieters and Tompkins (1999), LPSC XXX, 1286. [9] Lucey et al. (2002), LPSC XXXIII, 1056. [10] Tompkins et al. (1994), Icarus 110(2), 261-274. [11] Schonfeld and Bielefeld (1978), LPSC V, 3037-3048.

Trace elements in urban and suburban rainfall, Mersin, Northeastern Mediterranean

NASA Astrophysics Data System (ADS)

Özsoy, Türkan; Örnektekin, Sermin

2009-10-01

Spatial/temporal variabilities of rainwater constituents are examined based on soluble/insoluble trace elements, pH and electrical conductivity measurements in rainfall sampled during December 2003-May 2005 at two urban and two suburban sites in Mersin, an industrialized city of 850,000 inhabitants on the southern coast of Turkey. In the analyses, backward air mass trajectories for rainy days were used in addition to factor analyses, enrichment factors, phase distributions and correlations between trace elements. The pH varied from 4.8 to 8.5 with an average value of 6.2, reflecting a mainly alkaline regime. Mean concentrations of trace elements collected from urban and suburban sites are spatially variable. Based on the overall data, total concentrations of trace elements were ordered as Ca > Na > Fe > Al > Mg > K > Zn > Mn > Sr > Pb > Ni > Cr > Ba > Cu > Co > Cd. Mainly terrigeneous (Ca, Fe, Al) and, to a lesser extent, sea salt particles (Na, Mg) were shown to be the major source of trace elements. Excluding major cations, the solubilities of trace elements were found to be ordered as Sr > Zn > Ba > Mn > Cu > Ni > Cr > Fe > Al, confirming the lower solubility of crustal elements. Cd, Co and Pb were excluded from the above evaluation because of the low numbers of soluble samples allowing quantitative measurements. The solubilities of Al, Fe, Mn and particularly of Ni were found to be considerably lower than those reported for various sites around the world, most likely due to the effect of pH. During the entire sampling period, a total of 28 dust transport episodes associated with 31 red rain events were identified. Extremely high mean concentration ratios of Al (8.2), Fe (14.4) and Mn (13.1) were observed in red rain, compared to normal rain. The degree of this enhancement displayed a decrease from crustal to anthropogenic origin elements and the lowest enhancements were found for anthropogenic origin elements of Zn and Cd (both having a ratio of 1.1). Aerosol dust was found to be the main source of almost all analyzed elements in Mersin precipitation, regardless that they are crustal or anthropic derived elements. The magnitude of crustal source contribution to trace element budget of precipitation was at its highest levels for crustal originated elements, most probably due to much higher scavenging ratios of crustal elements compared to anthropogenic ones.

Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

NASA Astrophysics Data System (ADS)

Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

2016-05-01

Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation

PubMed Central

Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

2016-01-01

Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis. PMID:27194417

Synthesis of advanced aluminide intermetallic coatings by low-energy Al-ion radiation.

PubMed

Shen, Mingli; Gu, Yan; Zhao, Panpan; Zhu, Shenglong; Wang, Fuhui

2016-05-19

Metals that work at high temperatures (for instance, superalloys in gas-turbines) depend on thermally grown oxide (TGO, commonly alumina) to withstand corrosion attack. Nickel Aluminide (NiAl) as one superior alumina TGO former plays an important role in protective coatings for turbine blades in gas-turbine engines used for aircraft propulsion and power generation. Lowering TGO growth rate is essentially favored for offering sustainable protection, especially in thermal barrier coatings (TBC). However, it can only be achieved currently by a strategy of adding the third element (Pt or reactive elements) into NiAl during traditional diffusion- or deposition-based synthesis of the coating. Here we present a highly flexible Al-ion radiation-based synthesis of advanced NiAl coatings, achieving low TGO growth rate without relying on the third element addition. Our results expand the strategy for lowering TGO growth rate and demonstrate potentials for ion radiation in advancing materials synthesis.

Distribution Behavior of B and P during Al-Si Melt Directional Solidification with Open-Ended Crucible

NASA Astrophysics Data System (ADS)

Bai, Xiaolong; Ban, Boyuan; Li, Jingwei; Peng, Zhijian; Chen, Jian

2018-03-01

Distribution behavior of B and P during directional solidification of Al-20Si, Al-30Si and Al-40Si alloys has been investigated. Macrostructure of the Al-Si alloy ingots and concentration profile of elements B and P reveal that the elements segregate to eutectic Al-Si melt during growth of primary Si flakes, and P gradually segregates to the top of the ingots during directional solidification. An apparent segregation coefficient, ka, is introduced to describe the segregation behavior of B and P between the primary Si and the Al-Si melt and compared with thermodynamic theoretical equilibrium coefficients. The apparent segregation coefficients of B and P decrease with increase of solidification temperature.

Space geodiversity review: a case study in the southwestern region of Paraná State, Brazil.

NASA Astrophysics Data System (ADS)

Manosso, Fernando; Tauana Basso, Bruna; Alcindo Da Roza, Douglas; Souza dos Santos, Daniel

2015-04-01

Considering the strong global concern for nature protection, improvements emerge to support techniques to understand physical and biological means of selecting areas for environmental conservation. Most techniques take into consideration mainly the biological characteristics of nature, however as the nature is a complex of biotic and abiotic elements it becomes thus necessary the creation of parameters to understand the diversity of abiotic elements, their distribution, occurrence, threats and values as well. This paper aims to identify, quantify and perform a spatial analysis of the distribution of geodiversity in the southwestern region of Paraná State, Brazil, from the different concepts of geodiversity with the use of techniques on digital cartographic database in a Geographic Information System - GIS. Gray (2004) conceptualized geodiversity as the natural distribution of geology, including rocks, minerals, fossils, soil characteristics, land forms and processes (geomorphology), and their connections. Geodiversity is composed by the variability of abiotic nature, including lithological elements, tectonic, geomorphological, edaphic, hydrological, topographical and physical processes of the Earth surface, seas, oceans, together with natural endogenous, exogenous and anthropogenic processes that include a diversity of particles, elements and places (Serrano and Ruiz Flaño, 2007). Different methods of quantitative assessment of geodiversity in different territories were applied by Carcavilla et al (2007), Pellitero and González-Amuchastegui (2010), Navarro (2010), Katerina and Dušan (2008), Serrano et al (2007; 2009), Kozlowski (2010), Zwolinski and Stachowiak (2012), Thomas (2012), Hjort and Luoto (2010; 2012), Pellitero et al (2014), and Silva (2014). Considering geodiversity as the abiotic elements which constitute the landscape; it is important to mention that such set may vary spatially according to the occurrence of different geological formations, rock types, landforms, occurrence of fossils, drainage system, soil and other processes that outline the geodiversity. In addition to the wealth index number, which presents a quantity and area ratio, another way of analyzing the geodiversity of a case study is the abundance, dominance or the relative frequency of geodiversity (Carcavilla et al, 2007). As for the southwestern region of Paraná State case study, we used a set of cartographic databases at the 1:250.000 scale; for example: geomorphological and soil compartments, rivers, geological formations, structural lineaments, as well as temperature, rainfall and humidity average maps. The maps were organized relating the attribute tables, quantifying the sum of different elements each sample cell contained in a regular grid of 4km2. As a result, a map of the geodiversity wealth index of the region has been generated. High geodiversity wealth index comprises more carved valleys with steep slopes on some structural lines; on the other hand, less wealthy areas are located on softer relief plateaus with large hills, more homogeneous soils and lower relief structural control. These results, as well as adjustments and efficiency of the method seem to indicate an important tool for area management, especially regarding the selection of priority areas for nature conservation.

Mechanistic Study of Delamination Fracture in Al-Li Alloy C458 (2099)

NASA Technical Reports Server (NTRS)

Tayon, W. A.; Crooks, R. E.; Domack, M. S.; Wagner, J. A.; Beaudoin, A. J.; McDonald, R. J.

2009-01-01

Delamination fracture has limited the use of lightweight Al-Li alloys. In the present study, electron backscattered diffraction (EBSD) methods were used to characterize crack paths in Al-Li alloy C458 (2099). Secondary delamination cracks in fracture toughness samples showed a pronounced tendency for fracture between grain variants of the same deformation texture component. These results were analyzed by EBSD mapping methods and simulated with finite element analyses. Simulation procedures include a description of material anisotropy, local grain orientations, and fracture utilizing crystal plasticity and cohesive zone elements. Taylor factors computed for each grain orientation subjected to normal and shear stresses indicated that grain pairs with the largest Taylor factor differences were adjacent to boundaries that failed by delamination. Examination of matching delamination fracture surface pairs revealed pronounced slip bands in only one of the grains bordering the delamination. These results, along with EBSD studies, plasticity simulations, and Auger electron spectroscopy observations support a hypothesis that delamination fracture occurs due to poor slip accommodation along boundaries between grains with greatly differing plastic response.

Archean crust-mantle geochemical differentiation

NASA Astrophysics Data System (ADS)

Tilton, G. R.

Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

Archean crust-mantle geochemical differentiation

NASA Technical Reports Server (NTRS)

Tilton, G. R.

1983-01-01

Isotope measurements on carbonatite complexes and komatiites can provide information on the geochemical character and geochemical evolution of the mantle, including the sub-continental mantle. Measurements on young samples establish the validity of the method. These are based on Sr, Nd and Pb data from the Tertiary-Mesozoic Gorgona komatiite and Sr and Pb data from the Cretaceous Oka carbonatite complex. In both cases the data describe a LIL element-depleted source similar to that observed presently in MORB. Carbonatite data have been used to study the mantle beneath the Superior Province of the Canadian Shield one billion years (1 AE) ago. The framework for this investigation was established by Bell et al., who showed that large areas of the province appear to be underlain by LIL element-depleted mantle (Sr-85/Sr-86=0.7028) at 1 AE ago. Additionally Bell et al. found four complexes to have higher initial Sr ratios (Sr-87/Sr-86=0.7038), which they correlated with less depleted (bulk earth?) mantle sources, or possibly crustal contamination. Pb isotope relationships in four of the complexes have been studied by Bell et al.

The Genesis Mission: Solar Wind Conditions, and Implications for the FIP Fractionation of the Solar Wind.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reisenfeld, D. B.; Wiens, R. C.; Barraclough, B. L.

2005-01-01

The NASA Genesis mission collected solar wind on ultrapure materials between November 30, 2001 and April 1, 2004. The samples were returned to Earth September 8, 2004. Despite the hard landing that resulted from a failure of the avionics to deploy the parachute, many samples were returned in a condition that will permit analyses. Sample analyses of these samples should give a far better understanding of the solar elemental and isotopic composition (Burnett et al. 2003). Further, the photospheric composition is thought to be representative of the solar nebula, so that the Genesis mission will provide a new baseline formore » the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. Sample analysis is currently underway. The Genesis samples must be placed in the context of the solar and solar wind conditions under which they were collected. Solar wind is fractionated from the photosphere by the forces that accelerate the ions off of the Sun. This fractionation appears to be ordered by the first ionization potential (FIP) of the elements, with the tendency for low-FIP elements to be over-abundant in the solar wind relative to the photosphere, and high-FIP elements to be under-abundant (e.g. Geiss, 1982; von Steiger et al., 2000). In addition, the extent of elemental fractionation differs across different solarwind regimes. Therefore, Genesis collected solar wind samples sorted into three regimes: 'fast wind' or 'coronal hole' (CH), 'slow wind' or 'interstream' (IS), and 'coronal mass ejection' (CME). To carry this out, plasma ion and electron spectrometers (Barraclough et al., 2003) continuously monitored the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons, and those parameters were in turn used in a rule-based algorithm that assigned the most probable solar wind regime (Neugebauer et al., 2003). At any given time, only one of three regime-specific collectors (CH, IS, or CME) was exposed to the solar wind. Here we report on the regime-specific solar wind conditions from in-situ instruments over the course of the collection period. Further, we use composition data from the SWICS (Solar Wind Ion Composition Spectrometer) instrument on ACE (McComas et al., 1998) to examine the FIP fractionation between solar wind regimes, and make a preliminary comparison of these to the FIP analysis of Ulysses/SWICS composition data (von Steiger et al. 2000). Our elemental fractionation study includes a reevaluation of the Ulysses FIP analysis in light of newly reported photospheric abundance data (Asplund, Grevesse & Sauval, 2005). The new abundance data indicate a metallicity (Z/X) for the Sun almost a factor of two lower than that reported in the widely used compilation of Anders & Grevesse (1989). The new photospheric abundances suggest a lower degree of solar wind fractionation than previously reported by von Steiger et al. (2000) for the first Ulysses polar orbit (1991-1998).« less

Source Apportionment and Influencing Factor Analysis of Residential Indoor PM2.5 in Beijing

PubMed Central

Yang, Yibing; Liu, Liu; Xu, Chunyu; Li, Na; Liu, Zhe; Wang, Qin; Xu, Dongqun

2018-01-01

In order to identify the sources of indoor PM2.5 and to check which factors influence the concentration of indoor PM2.5 and chemical elements, indoor concentrations of PM2.5 and its related elements in residential houses in Beijing were explored. Indoor and outdoor PM2.5 samples that were monitored continuously for one week were collected. Indoor and outdoor concentrations of PM2.5 and 15 elements (Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Pb, Se, Tl, V, Zn) were calculated and compared. The median indoor concentration of PM2.5 was 57.64 μg/m3. For elements in indoor PM2.5, Cd and As may be sensitive to indoor smoking, Zn, Ca and Al may be related to indoor sources other than smoking, Pb, V and Se may mainly come from outdoor. Five factors were extracted for indoor PM2.5 by factor analysis, explained 76.8% of total variance, outdoor sources contributed more than indoor sources. Multiple linear regression analysis for indoor PM2.5, Cd and Pb was performed. Indoor PM2.5 was influenced by factors including outdoor PM2.5, smoking during sampling, outdoor temperature and time of air conditioner use. Indoor Cd was affected by factors including smoking during sampling, outdoor Cd and building age. Indoor Pb concentration was associated with factors including outdoor Pb and time of window open per day, building age and RH. In conclusion, indoor PM2.5 mainly comes from outdoor sources, and the contributions of indoor sources also cannot be ignored. Factors associated indoor and outdoor air exchange can influence the concentrations of indoor PM2.5 and its constituents. PMID:29621164

Source Apportionment and Influencing Factor Analysis of Residential Indoor PM2.5 in Beijing.

PubMed

Yang, Yibing; Liu, Liu; Xu, Chunyu; Li, Na; Liu, Zhe; Wang, Qin; Xu, Dongqun

2018-04-05

In order to identify the sources of indoor PM 2.5 and to check which factors influence the concentration of indoor PM 2.5 and chemical elements, indoor concentrations of PM 2.5 and its related elements in residential houses in Beijing were explored. Indoor and outdoor PM 2.5 samples that were monitored continuously for one week were collected. Indoor and outdoor concentrations of PM 2.5 and 15 elements (Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Pb, Se, Tl, V, Zn) were calculated and compared. The median indoor concentration of PM 2.5 was 57.64 μg/m³. For elements in indoor PM 2.5 , Cd and As may be sensitive to indoor smoking, Zn, Ca and Al may be related to indoor sources other than smoking, Pb, V and Se may mainly come from outdoor. Five factors were extracted for indoor PM 2.5 by factor analysis, explained 76.8% of total variance, outdoor sources contributed more than indoor sources. Multiple linear regression analysis for indoor PM 2.5 , Cd and Pb was performed. Indoor PM 2.5 was influenced by factors including outdoor PM 2.5 , smoking during sampling, outdoor temperature and time of air conditioner use. Indoor Cd was affected by factors including smoking during sampling, outdoor Cd and building age. Indoor Pb concentration was associated with factors including outdoor Pb and time of window open per day, building age and RH. In conclusion, indoor PM 2.5 mainly comes from outdoor sources, and the contributions of indoor sources also cannot be ignored. Factors associated indoor and outdoor air exchange can influence the concentrations of indoor PM 2.5 and its constituents.

Concentration and distribution of sixty-one elements in coals from DPR Korea

USGS Publications Warehouse

Hu, Jiawen; Zheng, B.; Finkelman, R.B.; Wang, B.; Wang, M.; Li, S.; Wu, D.

2006-01-01

Fifty coal samples (28 anthracite and 22 lignites) were collected from both main and small coal mines in DPR Korea prioritized by resource distribution and coal production. The concentrations of 61 elements in 50 coal samples were determined by several multielement and element-specific techniques, including inductively coupled plasma atomic emission spectrometry (ICP-AES), and inductively coupled plasma mass spectrometry (ICP-MS), ion chromatogram (IC), cold-vapor atomic absorption spectrometry (CV-AAS), and hydride generation atomic absorption spectrometry (HGAAS). The ranges, arithmetic means and geometric means of concentrations of these elements are presented. A comparison with crustal abundances (Clarke values) shows that some potentially hazardous elements in the coals of DPR Korea are highly enriched Li, B, S, Cl, Zn, As, Se, Cd, Sn, Sb, W, Te, Hg, Ag, Pb, and La, Ce, Dy, Tm, Ge, Mo, Cs, Tl, Bi, Th and U are moderately enriched. A comparison of ranges and means of elemental concentrations in DPR Korea, Chinese, and world coals shows the ranges of most elements in DPR Korea coals are very close to the ranges of world coals. Arithmetic means of most elements in DPR Korea coals are close to that of American coals. Most elements arithmetic means are higher in Jurassic and Paleogene coals than coals of other ages. In DPR Korea coals, only seven elements in early Permian coals are higher than other periods: Li, Zn, Se, Cd, Hg, Pb, and Bi. Only five elements B, As, Sr, Mo, W in Neogene coals have arithmetic means higher than others. SiO2 and Al2O 3 in ashes are more than 70% except six samples. The correlation between ash yields and major elements from high to low is in the order of Si>Al>Ti>K>Mg>Fe>Na>Ca>P>S. Most elements have high positive correlation with ash (r>0.5) and show high inorganic affinity. ?? 2005 Elsevier Ltd. All rights reserved.

Al-26, Pu-244, Ti-50, REE, and trace element abundances in hibonite grains from CM and CV meteorites

NASA Technical Reports Server (NTRS)

Fahey, A. J.; Mckeegan, K. D.; Zinner, E.; Goswami, J. N.

1987-01-01

Hibonites from the CM meteorites Murchison, Murray, and Cold Bokkeveld, and hibonites and Ti-rich pyroxene from the CV chondrite Allende are studied. Electron microprobe measurements of major element concentrations and track and ion probe measurements of Mg and Ti isotopic ratios, rare earth elements (REEs), and trace element abundances are analyzed. Correlations between isotopic anomalies in Ti, Al-26, Pu-244, and Mg-26(asterisk) are examined. Ti isotopic anomalies are compared with REE and trace element abundance patterns. Reasons for the lack of Al-26 in the hibonites are investigated and discussed. It is observed that there is no correlation between the Ti isotopic compositions, and the presence of Mg-26(asterisk), Pu-244, and REE and trace element patterns in individual hibonite samples. The data reveal that hibonites are not interstellar dust grains but formed on a short time scale and in localized regions of the early solar system.

The mechanical heterogeneity of the hard callus influences local tissue strains during bone healing: a finite element study based on sheep experiments.

PubMed

Vetter, A; Liu, Y; Witt, F; Manjubala, I; Sander, O; Epari, D R; Fratzl, P; Duda, G N; Weinkamer, R

2011-02-03

During secondary fracture healing, various tissue types including new bone are formed. The local mechanical strains play an important role in tissue proliferation and differentiation. To further our mechanobiological understanding of fracture healing, a precise assessment of local strains is mandatory. Until now, static analyses using Finite Elements (FE) have assumed homogenous material properties. With the recent quantification of both the spatial tissue patterns (Vetter et al., 2010) and the development of elastic modulus of newly formed bone during healing (Manjubala et al., 2009), it is now possible to incorporate this heterogeneity. Therefore, the aim of this study is to investigate the effect of this heterogeneity on the strain patterns at six successive healing stages. The input data of the present work stemmed from a comprehensive cross-sectional study of sheep with a tibial osteotomy (Epari et al., 2006). In our FE model, each element containing bone was described by a bulk elastic modulus, which depended on both the local area fraction and the local elastic modulus of the bone material. The obtained strains were compared with the results of hypothetical FE models assuming homogeneous material properties. The differences in the spatial distributions of the strains between the heterogeneous and homogeneous FE models were interpreted using a current mechanobiological theory (Isakson et al., 2006). This interpretation showed that considering the heterogeneity of the hard callus is most important at the intermediate stages of healing, when cartilage transforms to bone via endochondral ossification. Copyright © 2010 Elsevier Ltd. All rights reserved.

Influence of phase composition on microstructure and properties of Mg-5Al-0.4Mn-xRE (x = 0, 3 and 5 wt.%) alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braszczyńska-Malik, K.N., E-mail: kacha@wip.pcz.pl; Grzybowska, A.

2016-05-15

The microstructure and mechanical properties investigations of two AME503 and AME505 experimental alloys in as-cast conditions were presented. The investigated materials were fabricated on the basis of the AM50 commercial magnesium alloy with 3 and 5 wt.% cerium rich mischmetal. In the as-cast condition, both experimental alloys were mainly composed of α-Mg, Al{sub 11}RE{sub 3} and Al{sub 10}RE{sub 2}Mn{sub 7} intermetallic phases. Additionally, due to non-equilibrium solidification conditions, a small amount of α + γ divorced eutectic and Al{sub 2}RE intermetallic phase were revealed. The obtained results also show a significant influence of rare earth elements on Brinell hardness, tensilemore » and compression properties at ambient temperature and especially on creep properties at 473 K. Improved alloy properties with a rise in rare earth elements mass fraction results from an increase in Al{sub 11}RE{sub 3} phase volume fraction and suppression of α + γ eutectic volume fraction in the alloy microstructure. Additionally, the influence of rare earth elements on the dendrite arm space value was discussed. The presented results also proved the thermal stability of the intermetallic phases during creep testing. - Highlights: • Two different Mg-5Al-0.4Mn alloys containing 3 and 5 wt.% of rare earth elements were fabricated. • Addition of rare earth elements leads to a reduction of dendrite arm spaces. • Mechanical properties depend on the phase composition of the alloys. • The increase of the rare earth elements content causes rise of the creep resistance.« less

Intermediate Temperature Fluids Life Tests - Theory

NASA Technical Reports Server (NTRS)

Tarau, Calin; Sarraf, David B.; Locci, Ivan E.; Anderson, William G.

2008-01-01

There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 750 K, including space nuclear power system radiators, and high temperature electronics cooling. Potential working fluids include organic fluids, elements, and halides, with halides being the least understood, with only a few life tests conducted. Potential envelope materials for halide working fluids include pure aluminum, aluminum alloys, commercially pure (CP) titanium, titanium alloys, and corrosion resistant superalloys. Life tests were conducted with three halides (AlBr3, SbBr3, and TiCl4) and water in three different envelopes: two aluminum alloys (Al-5052, Al-6061) and Cp-2 titanium. The AlBr3 attacked the grain boundaries in the aluminum envelopes, and formed TiAl compounds in the titanium. The SbBr3 was incompatible with the only envelope material that it was tested with, Al-6061. TiCl4 and water were both compatible with CP2-titanium. A theoretical model was developed that uses electromotive force differences to predict the compatibility of halide working fluids with envelope materials. This theory predicts that iron, nickel, and molybdenum are good envelope materials, while aluminum and titanium halides are good working fluids. The model is in good agreement with results form previous life tests, as well as the current life tests.

Titanite petrochronology in the Fish Canyon Tuff

NASA Astrophysics Data System (ADS)

Schmitz, M. D.; Crowley, J. L.

2014-12-01

The petrologic complexity of the archtypical 'monotonous intermediate' Fish Canyon Tuff (FCT) has been previously established by a variety of mineralogical and geochemical proxies [1-2], and the unusual storage and eruptive dynamics of the FCT have been delineated by several geochronological studies [3-5]. Titanite is an apparent equilibrium phase in the penultimate FCT magma, and can be linked petrographically to hornblende crystals that preserve up-temperature core-to-rim zoning profiles. As a reactive, trace element-rich phase, we hypothesized that titanite may record an intracrystalline record of magma chamber dynamics. Titanite crystals from the same separate analyzed in [4] were oriented and doubly-polished to yield characteristic wedge-shaped cross-sectional wafers approximately 300 µm in thickness. BSE imaging guided LA-ICPMS analyses of a full suite of trace elements using a 25 µm beam diameter and crater depth on multiple locations across both sides of the wafer. Most titanite crystals are characterized by large variations in trace elements, including at least two generations of REE-enriched, actinide-poor, low Sr, large Eu anomaly cores overgrown by REE-depleted, actinide-rich, high Sr domains with small Eu anomalies and distinctive concave-up middle to heavy REE patterns. Trace element contents and patterns correlate strongly with Eu anomaly; intermediate compositions are abundant and spatially correlated to reaction zones between core and rim domains. Within the context of the batholithic rejuvenation model for the FCT magma [1-2], these trace element variations are interpreted to record the partial melting of a differentiated crystalline FCT precursor and its hybridization with a more 'mafic' flux. ID-TIMS dating of end-member titanites confirm older ages (ca 28.4 to 29.0 Ma) for cores and define a younger age for rejuvenation of ca 28.2 Ma, consistent with recent U-Pb zircon and 40Ar/39Ar studies [5-7]. [1] Bachmann & Dungan (2002) Am Mineral 87, 1062-1076. [2] Bachmann et al (2002) J Petrology 43, 1469-1503. [3] Bachmann et al (2007) Chem Geol 236, 134-166. [4] Schmitz & Bowring (2001) GCA 65, 2571-2587. [5] Wotzlaw et al (2013) Geology 41, 867-870. [6] Rivera et al. (2011) EPSL 311, 420-426. [7] Kuiper et al (2008) Science 320, 500-504.

How Trace Element Levels of Public Drinking Water Affect Body Composition in Turkey.

PubMed

Cetin, Ihsan; Nalbantcilar, Mahmut Tahir; Tosun, Kezban; Nazik, Aydan

2017-02-01

Since waterborne minerals appear in ionic form and are readily absorbed by the gastrointestinal tract, drinking water could be a crucial source of mineral intake. However, no comprehensive research has yet determined how trace elements in drinking water relate to body composition. We aimed to assess the relationship between clinically important trace elements in public drinking water and body composition in average, overweight and obese individuals in Turkey. The study's population consisted of 423 participants: 143 overweight, 138 obese and 142 healthy control individuals, grouped according to clinical cutoff points of body mass index (BMI). We measured levels of lithium (Li), nickel (Ni), lead (Pb), silicon (Si), tin (Sn), strontium (Sr), boron (B), aluminium (Al), barium (Ba) and rubidium (Rb) in samples from wells of municipal water by using inductively coupled plasma mass spectrometry. We gauged all the participants' body composition measurements with a BC-418 body composition analyser. In all the participants, body weight values showed significant positive correlations with Ni levels in drinking water, as did BMI values with Al levels and percentage of obesity with Ni, Si and B levels. In particular, Ni levels showed significant positive correlations with the basal metabolic rate, activity calories, and total activity of participants. Giving findings showing correlations between obesity-related parameters and Al, Si, B and Ni content in drinking water, we hope that these associations will be clarified with further studies including cellular, experimental and clinical studies. Hence, medical practitioners must be aware of trace element levels in drinking water for overweight and obese patients.

Experimental and Computational Investigation of High Entropy Alloys for Elevated-Temperature Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liaw, Peter; Zhang, Fan; Zhang, Chuan

2016-07-30

To create and design novel structural materials with enhanced creep-resistance, fundamental studies have been conducted on high-entropy alloys (HEAs), using (1) thermodynamic calculations, (2) mechanical tests, (3) neutron diffraction, (4) characterization techniques, and (5) crystal-plasticity finite-element modeling (CPFEM), to explore future candidates for next-generation power plants. All the constituent binary and ternary systems of the Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems were thermodynamically modeled within the whole composition range. Comparisons between the calculated phase diagrams and literature data are in good agreement. Seven types of HEAs were fabricated from Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems. The Al xCrCuFeMnNi HEAs have disordered [face-centered cubic (FCC)more » + body-centered cubic (BCC)] crystal structures, not FCC or BCC single structure. Excessive alloying of the Al element results in the change of both microstructural and mechanical properties in Al xCoCrFeNi HEAs. There are mainly three structural features in Al xCoCrFeNi: (1) the morphology, (2) the volume fractions of the constitute phases, and (3) existing temperatures of all six phases. After homogenization, the Al 0.3CoCrFeNi material is a pure FCC solid solution. After aging at 700 °C for 500 hours, the optimal microstructure combinations, the FCC matrix, needle-like B2 phase within grains, and granular σ phase along grain boundary, is achieved for Al 0.3CoCrFeNi. The cold-rolling process is utilized to reduce the grain size of Al 0.1CoCrFeNi and Al 0.3CoCrFeNi. The chemical elemental partitioning of FCC, BCC, B2, and σphases at different temperatures, before and after mechanical tests, in Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems are quantitatively characterized by both synchrotron X-ray diffraction, neutron diffraction with levitation, scanning electron microscopy (SEM), advanced atom probe tomography (APT), and transmission electron microscopy (TEM). In-situ neutron diffraction experiments were conducted to study the strengthening effect of B2 phase on tensile properties of Al 0.3CoCrFeNi HEAs directly. The results shows the creep behavior of Al 0.3CoCrFeNi is superior to conventional alloys, and the heat treatment introduces secondary B2 phase into the FCC matrix, which increase the yielding strength, decrease the ductility, diminish the serrated flow during compression tests at high temperatures. In summary, the outcomes of the development of the HEAs with creep resistance include: (1) Suitable candidates, for the application to boilers and steam and gas turbines at temperatures above 760 °C and a stress of 35 MPa. (2) Fundamental understanding on the precipitate stability and deformation mechanisms of both single-phase and precipitate-strengthened alloys at room and elevated temperatures, and (3) The demonstration of an integrated approach, coupling modeling [thermodynamic calculations and crystal-plasticity finite-element modeling (CPFEM)] and focused experiments, to identify HEAs that outperform conventional alloys for high-temperature applications, which will be applicable for the discovery and development of other high-temperature materials in the power-generating industry.« less

Multi-elements determination in medical and edible Alpinia oxyphylla and Morinda officinalis and their decoctions by ICP-MS.

PubMed

Zhao, Xiangsheng; Wei, Jianhe; Shu, Xiaoyan; Kong, Weijun; Yang, Meihua

2016-12-01

Contents of twenty elements (Mg, K, Ca, Na, Fe, Al, Zn, Ba, Mn, Cu, Mo, Cr, Ni, As, Se, Cd, Hg, Tl, Pb and V) in two medical and edible plant species, Alpinia oxyphylla and Morinda officinalis were simultaneously determined by inductively coupled plasma-mass spectrometry (ICP-MS) method after microwave digestion with HNO 3 -H 2 O 2 (6:1, v/v) as the digestion solvent. Certified standard reference material Poplar leaf was used to assess the accuracy of the method. The greatest contents of Mg, K, Ca, Al, Fe and Na were found in dried Alpinia oxyphylla and Morinda officinalis samples. The contents of five heavy metals including Pb, Cd, As, Hg and Cu in Alpinia oxyphylla did not exceed the limits. The contents of Pb in 76.67% samples and Cd in two batches of Morinda officinalis samples exceeded the limits set by Chinese Pharmacopeia. The contents of the selected elements in different parts (leaves, stems, roots and fruits) of Alpinia oxyphylla varied considerably. The highest concentrations of Mg, Ca, Mn and Se were found in the leaves of Alpinia oxyphylla, at the same time, while, the contents of 9 elements including Cd, Cr, Cu, As, Pb in the roots were the highest. The transfer ratios of selected elements from both species of herbs into their decoctions were reduced. Especially for the heavy metals, the transfer ratios were below 30% except As (79.73%) in Morinda officinalis. The results showed that decoction of the samples may reduce the intake of heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Review of atmospheric metallic elements in Asia during 2000-2004

NASA Astrophysics Data System (ADS)

Fang, Guor-Cheng; Wu, Yuh-Shen; Huang, Shih-Han; Rau, Jui-Yeh

Metallic element transfer through the atmosphere is a significant part of the biogeochemical cycle of these elements. Natural and anthropogenic were two processes which can increase heavy metal concentrations in the atmosphere. Atmospheric particulates, especially secondary anthropogenic fine particles (PM 2.5), have been influence human health. Generally speaking, the total daily mortality increases by approximately 1% for every 10 μg m -3 increase in PM 10 concentration (Lippmann, 1998). This is why the PM 10 and PM 2.5 measurements are included in the US ambient air quality standards (US-EPA, 1987 for PM 10; 1996 for PM 2.5) (Querol et al., 2001). In recent years, since the great efforts made by Taiwan government towards the reduction of O 3 and PM 10 concentrations by controlling the emission rates of local pollutants sources, the frequency of exceeded PSI has gradually decrease the value of 4.9% in 1999 (Taiwan EPA, 2000). Urban populations are exposed to metals in suspended particles and these are often well above natural background levels owing to anthropogenic processes (Espinosa et al., 2002). This results in elevated metal concentrations that can pose an important risk to human health. Understanding emissions from traffic includes identification of the sources, which is also crucial for designing control measures. Road traffic involves numerous potential sources of metals, combustion products from fuel and oil, wear products from tires, brake linings, bearings, coach and road construction materials, and re-suspension of soil and road dust. The different sample collection devices, pretreatment and analysis methods were discussed in this study. The purpose of this study arranges the atmospheric metallic elements investigations in Asia regions. The data obtained here can also help to understand the sources, concentration, phase distribution and health impact of atmospheric metallic elements in Asian countries.

Extensive Aspartoacylase Expression in the Rat Central Nervous System

DTIC Science & Technology

2011-01-01

pathways are shown in panel (A) including the corpus callosum (cc), anterior com- missure (see also C; aco), and fornix ( fx ). The subfornical organ (sfo...14 MOFFETT ET AL. GLIA protein. That antibody and the one used in the current study both stained the same cellular elements. Astro - cytes were the

Senator Doug Jones (D-AL) Tour of MSFC Facilities

NASA Image and Video Library

2018-02-22

Senator Doug Jones (D-AL.) and wife, Louise, tour Marshall Space Flight facilities. Steve Doering, manager, Stages Element, Space Launch System (SLS) program at MSFC, views the test stand 4693 where key SLS structural elements will be subjected to stress testing simulating space flight.

Taking Another Look: Zr and Y abundances in Halo Stars

NASA Astrophysics Data System (ADS)

Burris, Debra L.; Jones, E.

2007-12-01

The elements Zirconium and Yttrium are produced via neutron capture (n-capture). These elements reside in the mass range where there is uncertainty about the production mechanism at early time. The rapid n-capture process (r-process) was believed to be responsible for the production, but no study (Burris et al 2000, Gilroy et al 1988 and others) has been able to successfully use the r-process to reproduce the abundance signature for elements in this mass range for metal-poor halo stars. It has been suggested (Sneden and Cowan 2003) that there may be an undiscovered component to the r-process. New abundance calculations for these elements have been conducted for a sample of metal-poor halo stars. Transition probabilities for Zr II from Malcheva et al (2006) and for YII from Hannaford et al (1982) were utilized in these calculations. This work is supported in part by the AAS Small Grant Program, the Arkansas Space Grant Consortium and the UCA Undergraduate Research Council.

Driving forces of redistribution of elements during quasicrystalline phase formation under heating of mechanically alloyed Al65Cu23Fe12 powder

NASA Astrophysics Data System (ADS)

Tcherdyntsev, V. V.; Kaloshkin, S. D.; Shelekhov, E. V.; Principi, G.; Rodin, A. O.

2008-02-01

Al65Cu23Fe12 alloys were prepared by ball milling of the elemental powders mixture. Phase and structural transformations at heating of as-milled powders were investigated by X-ray diffraction analysis. Precision analysis of Mössbauer spectra was performed to check the adequacy of the fitting of X-ray diffraction patterns. The results were compared with the data of differential scanning and solution calorimetry, as well as with the thermodynamic literature data, in order to estimate the driving forces of redistribution of elements that preceded the formation of single-phase quasicrystalline structure. The heat of elements mixing, which is positive for Cu-Fe system and negative for Al-Fe and Al-Cu systems, was supposed to be a decisive factor for phase transformations during heating of the alloy. The correlation between sequence of phase transformations during heating and the thermodynamic data was discussed and the scheme describing phase transformations observed was proposed.

Trace elements distribution in hawksbill turtle (Eretmochelys imbricata) and green turtle (Chelonia mydas) tissues on the northern coast of Bahia, Brazil.

PubMed

de Macêdo, Gustavo R; Tarantino, Taiana B; Barbosa, Isa S; Pires, Thaís T; Rostan, Gonzalo; Goldberg, Daphne W; Pinto, Luis Fernando B; Korn, Maria Graças A; Franke, Carlos Roberto

2015-05-15

Concentrations of elements (As, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn) were determined in liver, kidneys and bones of Eretmochelys imbricata and Chelonia mydas specimens found stranded along the northern coast of Bahia, Brazil. Results showed that the concentrations of Cd, Cu, Ni and Zn in the liver and kidneys of juvenile C. mydas were the highest found in Brazil. We also observed a significant difference (p<0.05) on the bioaccumulation of trace elements between the two species: Al, Co, Mo, Na and Se in the liver; Al, Cr, Cu, K, Mo, Ni, Pb, Sr and V in the kidneys; and Al, Ba, Ca, Cd, Mn, Ni, Pb, Se, Sr and V in the bones. This study represents the first report on the distribution and concentration of trace elements in E. imbricata in the Brazilian coast. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trace elements are associated with urinary 8-hydroxy-2'-deoxyguanosine level: a case study of college students in Guangzhou, China.

PubMed

Lu, Shaoyou; Ren, Lu; Fang, Jianzhang; Ji, Jiajia; Liu, Guihua; Zhang, Jianqing; Zhang, Huimin; Luo, Ruorong; Lin, Kai; Fan, Ruifang

2016-05-01

Many trace heavy elements are carcinogenic and increase the incidence of cancer. However, a comprehensive study of the correlation between multiple trace elements and DNA oxidative damage is still lacking. The aim of this study is to investigate the relationships between the body burden of multiple trace elements and DNA oxidative stress in college students in Guangzhou, China. Seventeen trace elements in urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of DNA oxidative stress, was also measured using liquid chromatography tandem mass spectrometer (LC-MS/MS). The concentrations of six essential elements including manganese (Mn), copper (Cu), nickel (Ni), selenium (Se), strontium (Sr), and molybdenum (Mo), and five non-essential elements including arsenic (As), cadmium (Cd), aluminum (Al), stibium (Sb), and thallium (Tl), were found to be significantly correlated with urinary 8-OHdG levels. Moreover, urinary levels of Ni, Se, Mo, As, Sr, and Tl were strongly significantly correlated with 8-OHdG (P < 0.01) concentration. Environmental exposure and dietary intake of these trace elements may play important roles in DNA oxidative damage in the population of Guangzhou, China.

High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

NASA Astrophysics Data System (ADS)

Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

2018-03-01

The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

High Temperature Oxidation of Hot-Dip Aluminized T92 Steels

NASA Astrophysics Data System (ADS)

Abro, Muhammad Ali; Hahn, Junhee; Lee, Dong Bok

2018-05-01

The T92 steel plate was hot-dip aluminized, and oxidized in order to characterize the high-temperature oxidation behavior of hot-dip aluminized T92 steel. The coating consisted of Al-rich topcoat with scattered Al3Fe grains, Al3Fe-rich upper alloy layer with scattered (Al, Al5Fe2, AlFe)-grains, and Al5Fe2-rich lower alloy layer with scattered (Al5Fe2, AlFe)-grains. Oxidation at 800 °C for 20 h formed (α-Al2O3 scale)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer), while oxidation at 900 °C for 20 h formed (α-Al2O3 scale plus some Fe2O3)/(AlFe layer)/(AlFe3 layer)/(α-Fe(Al) layer) from the surface. During oxidation, outward migration of all substrate elements, inward diffusion of oxygen, and back and forth diffusion of Al occurred according to concentration gradients. Also, diffusion transformed and broadened AlFe and AlFe3 layers dissolved with some oxygen and substrate alloying elements. Hot-dip aluminizing improved the high-temperature oxidation resistance of T92 steel through preferential oxidation of Al at the surface.

Infrastructure resources for clinical research in amyotrophic lateral sclerosis.

PubMed

Sherman, Alexander V; Gubitz, Amelie K; Al-Chalabi, Ammar; Bedlack, Richard; Berry, James; Conwit, Robin; Harris, Brent T; Horton, D Kevin; Kaufmann, Petra; Leitner, Melanie L; Miller, Robert; Shefner, Jeremy; Vonsattel, Jean Paul; Mitsumoto, Hiroshi

2013-05-01

Clinical trial networks, shared clinical databases, and human biospecimen repositories are examples of infrastructure resources aimed at enhancing and expediting clinical and/or patient oriented research to uncover the etiology and pathogenesis of amyotrophic lateral sclerosis (ALS), a rapidly progressive neurodegenerative disease that leads to the paralysis of voluntary muscles. The current status of such infrastructure resources, as well as opportunities and impediments, were discussed at the second Tarrytown ALS meeting held in September 2011. The discussion focused on resources developed and maintained by ALS clinics and centers in North America and Europe, various clinical trial networks, U.S. government federal agencies including the National Institutes of Health (NIH), the Agency for Toxic Substances and Disease Registry (ATSDR) and the Centers for Disease Control and Prevention (CDC), and several voluntary disease organizations that support ALS research activities. Key recommendations included 1) the establishment of shared databases among individual ALS clinics to enhance the coordination of resources and data analyses; 2) the expansion of quality-controlled human biospecimen banks; and 3) the adoption of uniform data standards, such as the recently developed Common Data Elements (CDEs) for ALS clinical research. The value of clinical trial networks such as the Northeast ALS (NEALS) Consortium and the Western ALS (WALS) Consortium was recognized, and strategies to further enhance and complement these networks and their research resources were discussed.

Characterizing marine particles and their impact on biogeochemical cycles in the GEOTRACES program

NASA Astrophysics Data System (ADS)

Anderson, Robert F.; Hayes, Christopher T.

2015-04-01

Trace elements and their isotopes (TEIs) are of priority interest in several subdisciplines of oceanography. For example, the vital role of trace element micronutrients in regulating the growth of marine organisms, which, in turn, may influence the structure and composition of marine ecosystems, is now well established (Morel and Price, 2003; Twining and Baines, 2013). Natural distributions of some TEIs have been severely impacted by anthropogenic emissions, leading to substantial perturbations of natural ocean inventories. Pb and Hg, for example, (Lamborg et al., 2002; Schaule and Patterson, 1981), may represent a significant threat to human food supply. Furthermore, much of our knowledge of past variability in the ocean environment, including the ocean's role in climate change, has been developed using TEI proxies archived in marine substrates such as sediments, corals and microfossils. Research in each of these areas relies on a comprehensive knowledge of the distributions of TEIs in the ocean, and on the sensitivity of these distributions to changing environmental conditions. With numerous processes affecting the regional supply and removal of TEIs in the ocean, a comprehensive understanding of the marine biogeochemical cycles of TEIs can be attained only by a global, coordinated, international effort. GEOTRACES, an international program designed to study the marine biogeochemical cycles of trace elements and their isotopes (Anderson et al., 2014; Henderson et al., 2007), aims to achieve these goals.

Not rare. But, endangered Elemental profiles of three corticolous lichen species on red spruce in Maine. [Usnea subfloridana; Platismatia glauca; Hypogymnia physodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stubbs, C.S.; Homola, R.H.

1990-01-01

Usnea subfloridana Stirton, Platismatia glauca (L.) Club. and Club., and Hypogymnia physodes (L.) Nyl. are lichen species moderately to highly sensitive to air pollutants, including acid deposition and ozone. Some researchers have attributed depauperate populations and local extinctions of these species to poor air quality. Since 1985, areas of Maine annually experienced mean summer rain and fog events of pH 4.5 or lower and ozone levels above national standards. Given this possible threat to these and other pollution sensitive species, baseline elemental analyses for Ca, K, P, Mg, Al, B, Fe, Cu, Mn, Zn, N, S, Na, and Pb weremore » performed in 1986 on coastal and inland populations on Picea rubens L. Elemental analyses were again performed on nontransplanted and transplanted lichens from the same populations in 1988. There were statistically significant differences in elemental profiles between nontransplanted 1986 and 1988 samples for all three species, such as significant decreases in Ca and Mg concentrations, and increases in Al, Cu, Fe, and Zn for U. subfloridana. Elemental concentrations between nontransplanted and transplanted material differed significantly, but no consistent pattern emerged. These results, coupled with other evidence (such as luxuriance and density ratings), suggest that both inland and coastal populations of U. subfloridana on red spruce are experiencing ecophysiological stress.« less

Developing precipitation hardenable high entropy alloys

NASA Astrophysics Data System (ADS)

Gwalani, Bharat

High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi 2 (0 < x < 1.5) complex concentrated alloys as a candidate system. The composition gradient has been achieved from CrCuFeNi2 to Al 1.5CrCuFeNi2 over a length of ˜25 mm, deposited using the laser engineered net shaping process from a blend of elemental powders. With increasing Al content, there was a gradual change from an fcc-based microstructure (including the ordered L12 phase) to a bcc-based microstructure (including the ordered B2 phase), accompanied with a progressive increase in microhardness. Based on this combinatorial assessment, two promising fcc-based precipitation strengthened systems have been identified; Al0.3CuCrFeNi2 and Al0.3CoCrFeNi, and both compositions were subsequently thermo-mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (gamma') and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale gamma' precipitates. Furthermore, precipitation of bcc based ordered phase B2 in Al0.3CoCrFeNi can further strengthen the alloy. Fine-tuning the microstructure by thermo-mechanical treatments achieved a wide range of mechanical properties in the same alloy. The Al0.3CoCrFeNi HEA exhibited ultimate tensile strength (UTS) of ˜250 MPa and ductility of ˜65%; a UTS of ˜1100 MPa and ductility of ˜30%; and a UTS of 1850 MPa and a ductility of 5% after various thermo-mechanical treatments. Grain sizes, precipitates type and size scales manipulated in the alloy result in different strength ductility combinations. Henceforth, the alloy presents a fertile ground for development by grain boundary strengthening and precipitation strengthening, and offers very high activation energy of grain growth aptly suitable for high-temperature applications.

Refining a definition of reflection for the being as well as doing the work of a physician.

PubMed

Wald, Hedy S

2015-04-21

Reflection is core to professional competency and supports the active, constructive process of professional identity formation. Medical educators thus grapple with operationalizing and effectively integrating reflection as a foundational construct within health care professions education and practice. Core elements of reflection including role of emotions and awareness of self, other and situation, do not appear within various working definitions of reflection. This observation as well as noted recent shift in medical education toward emphasis on the "being" as well as "doing the work" of a physician led to the author's proposed refining of Sandars' reflection definition and expansion of Nguyen et al.'s reflection model. A refined reflection definition is offered for a more inclusionary approach. A caveat regarding potential for expected reflective learning outcomes (given reflection as a process) is provided and the integral role of mentor-enhanced reflection is discussed. Reflection as a continuum is highlighted and exemplified within Wald et al.'s REFLECT rubric and Nguyen et al.'s reflection model.

Oxidation, carburization and/or sulfidation resistant iron aluminide alloy

DOEpatents

Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier S.; Hajaligol, Mohammad R.; Lilly, Jr., A. Clifton

2003-08-19

The invention relates generally to aluminum containing iron-base alloys useful as electrical resistance heating elements. The aluminum containing iron-base alloys have improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The alloy has an entirely ferritic microstructure which is free of austenite and includes, in weight %, over 4% Al, .ltoreq.1% Cr and either .gtoreq.0.05% Zr or Zro.sub.2 stringers extending perpendicular to an exposed surface of the heating element or .gtoreq.0.1% oxide dispersoid particles. The alloy can contain 14-32% Al, .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Zr, .ltoreq.1% C, .ltoreq.0.1% B. .ltoreq.30% oxide dispersoid and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, .ltoreq.1% oxygen, .ltoreq.3% Cu, balance Fe.

Elements of the Chicxulub Impact Structure as Revealed in SRTM and Surface GPS Topographic Data

NASA Technical Reports Server (NTRS)

Kinsland, Gary L.; Sanchez, Gary; Kobrick, Michael; Cardador, Manuel Hurtado

2003-01-01

Pope et al. [1] utilized the elevations from the Petroleos Mexicanos (PEMEX) gravity data files to show that the main component of the surface expression of the Chicxulub Impact Structure is a roughly semi-circular, lowrelief depression about 90 km in diameter. They also identified other topographic features and the elements of the buried impact, which possibly led to the development of these features. These are summarized in Table 1. Kinsland et al. [2] presented a connection between these topographic anomalies, small gravity anomalies and buried structure of the impact. Very recently we have acquired digital topography data from NASA s Shuttle Radar Topography Mission (SRTM). Our subset covers 6 square degrees from 20deg N 91degW to 22deg N 88degW (corner to corner) with a pixel size of about 90m. This area includes all of the identified portion of the crater on land.

Elemental ratios and enrichment factors in aerosols from the US-GEOTRACES North Atlantic transects

NASA Astrophysics Data System (ADS)

Shelley, Rachel U.; Morton, Peter L.; Landing, William M.

2015-06-01

The North Atlantic receives the highest aerosol (dust) input of all the oceanic basins. Dust deposition provides essential bioactive elements, as well as pollution-derived elements, to the surface ocean. The arid regions of North Africa are the predominant source of dust to the North Atlantic Ocean. In this study, we describe the elemental composition (Li, Na, Mg, Al, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Cd, Sn, Sb, Cs, Ba, La, Ce, Nd, Pb, Th, U) of the bulk aerosol from samples collected during the US-GEOTRACES North Atlantic Zonal Transect (2010/11) in order to highlight the differences between a Saharan dust end-member and the reported elemental composition of the upper continental crust (UCC), and the implications this has for identifying trace element enrichment in aerosols across the North Atlantic basin. As aerosol titanium (Ti) is less soluble than aerosol aluminum (Al), it is a more conservative tracer for lithogenic aerosols and trace element-to-Ti ratios. However, the presence of Ti-rich fine aerosols can confound the interpretation of elemental enrichments, making Al a more robust tracer of aerosol lithogenic material in this region.

Mineralogical and Geochemical Analysis of Howardite DaG 779: understanding geological evolution of asteroid (4) Vesta

NASA Astrophysics Data System (ADS)

Marcel Müller, Christian; Mengel, Kurt; Singh Thangjam, Guneshwar; Weckwerth, Gerd

2016-04-01

The HED meteorites, a clan of stony achondrites, are believed to originate from asteroid (4) Vesta (e.g. Mittlefehldt et al. (2015)). Recent evolution models (e.g. Toplis et al. (2013)) and observations from Dawn spacecraft data (e.g., Prettyman et al. (2013)) indicate that diogenites form the lower crust and uppermost mantle of (4) Vesta. Deep seated material excavated by large impacts such as the Rheasilvia- and Veneneiaforming event should be present in howardites. We analysed a slice of howardite DaG 779 which had been recovered from the Libyan Desert in 1999 and was briefly described by Grossmann (2000). The data presented here include electron microprobe, bulk-rock XRD and XRF as well as trace element analysis by ICP-MS and INA. The petrographic results confirm earlier observations that DaG 779 is polymict and mainly contains diogenite and eucrite clasts. Mass balance calculations using bulk-rock and microprobe major element data reveal a modal mineralogy of 77% orthopyroxene, 8% plagioclase, 7% clinopyroxene and 2% spinels, the rest being olivine, SiO2-phases, sulphides, and native Fe(Ni). When compared with the element compilation recently reported by Mittlefehldt (2015) the 39 trace element analysed here (including REE and PGE) confirm that this howardite is clearly dominated by diogenite. Beside the modal petrographic information, a number of more detailed observations obtained from microprobe investigations reveal fresh and recrystallized glasses, troilite-orthopyroxene symplectites from a mixed silicate-sulphide melt giving rise to graphic intergrowths as well as vermicular and reticular FeS in highly disrupted clasts. While the origin of the FeS in these clasts is not clear yet, its particular shape and distribution indicates that this mineral has been (partially) molten and recrystallized from a sulphide melt. The silicate minerals around these FeS occurrences are recrystallized but there is no indication for a partial silicate melt. Further metasomatic reactions were observed between clinopyroxene (pigeonite) and a sulphide-bearing agent, according to the principal reaction Pigeonite (Fe-rich) + S2 ↔ FeS + Augit (Mg-rich) + SiO2. This type of metasomatism (Zhang et al. (2013)) is not well understood yet. References: Grossman, J. N. (2000): The Meteoritical Bulletin, No. 84, 2000 August. Meteoritics & Planetary Science, 35: A119-A225. doi: 10.1111/j.1945-5100.2000.tb01797.x. Toplis, M.J. et al. (2013): Chondritic models of 4 Vesta: Implications for geochemical and geophysical properties. Meteoritics & Planetary Science, 48: 2300-2315. doi: 10.1111/maps.12195. Zhang, A. et al. (2013): Record of S-rich vapors on asteroid 4 Vesta: Sulfurization in the Northwest Africa 2339 eucrite. Geochim. Cosmochim. Acta 109, 1-13. Mittlefehldt, D.W., (2015): Asteroid (4) Vesta: I. The howardite-eucrite-diogenite (HED) clan of meteorites. Chemie Erde-Geochem. 75, 2, 155-183. Prettyman, T.H. et al. (2013): Neutron absorption constraints on the composition of 4 Vesta. Meteoritics & Planetary Science 48:2211-2236.

Chemical analyses of micrometre-sized solids by a miniature laser ablation/ionisation mass spectrometer (LMS)

NASA Astrophysics Data System (ADS)

Tulej, Marek; Wiesendanger, Reto; Neuland, Maike; Meyer, Stefan; Wurz, Peter; Neubeck, Anna; Ivarsson, Magnus; Riedo, Valentine; Moreno-Garcia, Pavel; Riedo, Andreas; Knopp, Gregor

2017-04-01

Investigation of elemental and isotope compositions of planetary solids with high spatial resolution are of considerable interest to current space research. Planetary materials are typically highly heterogenous and such studies can deliver detailed chemical information of individual sample components with the sizes down to a few micrometres. The results of such investigations can yield mineralogical surface context including mineralogy of individual grains or the elemental composition of of other objects embedded in the sample surface such as micro-sized fossils. The identification of bio-relevant material can follow by the detection of bio-relevant elements and their isotope fractionation effects [1, 2]. For chemical analysis of heterogenous solid surfaces we have combined a miniature laser ablation mass spectrometer (LMS) (mass resolution (m/Dm) 400-600; dynamic range 105-108) with in situ microscope-camera system (spatial resolution ˜2um, depth 10 um). The microscope helps to find the micrometre-sized solids across the surface sample for the direct mass spectrometric analysis by the LMS instrument. The LMS instrument combines an fs-laser ion source and a miniature reflectron-type time-of-flight mass spectrometer. The mass spectrometric analysis of the selected on the sample surface objects followed after ablation, atomisation and ionisation of the sample by a focussed laser radiation (775 nm, 180 fs, 1 kHz; the spot size of ˜20 um) [4, 5, 6]. Mass spectra of almost all elements (isotopes) present in the investigated location are measured instantaneously. A number of heterogenous rock samples containing micrometre-sized fossils and mineralogical grains were investigated with high selectivity and sensitivity. Chemical analyses of filamentous structures observed in carbonate veins (in harzburgite) and amygdales in pillow basalt lava can be well characterised chemically yielding elemental and isotope composition of these objects [7, 8]. The investigation can be prepared with high selectivity since the host composition is typically readily different comparing to that of the analysed objects. In depth chemical analysis (chemical profiling) is found in particularly helpful allowing relatively easy isolation of the chemical composition of the host from the investigated objects [6]. Hence, both he chemical analysis of the environment and microstructures can be derived. Analysis of the isotope compositions can be measured with high level of confidence, nevertheless, presence of cluster of similar masses can make sometimes this analysis difficult. Based on this work, we are confident that similar studies can be conducted in situ planetary surfaces delivering important chemical context and evidences on bio-relevant processes. [1] Summons et al., Astrobiology, 11, 157, 2011. [2] Wurz et al., Sol. Sys. Res. 46, 408, 2012. [3] Riedo et al., J. Anal. Atom. Spectrom. 28, 1256, 2013. [4] Riedo et al., J. Mass Spectrom.48, 1, 2013. [5] Tulej et al., Geostand. Geoanal. Res., 38, 423, 2014. [6] Grimaudo et al., Anal. Chem. 87, 2041, 2015 [7] Tulej et al., Astrobiology, 15, 1, 2015. [8] Neubeck et al., Int. J. Astrobiology, 15, 133, 2016.

Modulating the band structure and sub-bandgap absorption of Co-hyperdoped silicon by co-doping with shallow-level elements

NASA Astrophysics Data System (ADS)

Dong, Xiao; Fang, Xiuxiu; Wang, Yongyong; Song, Xiaohui; Lu, Zhansheng

2018-06-01

Hyperdoped group-III elements can lower the Fermi energy in the band structures of Co-hyperdoped silicon. When the Co-to-X (X = B, Al, Ga) ratio is 2:1, the intermediate band (IB) in the bandgap includes the Fermi energy and is partially filled by electrons, which is in accordance with the requirement of an IB material. The hyperdoped X atoms can cause the blueshift of the sub-bandgap absorption of the compound compared with the material with no shallow-level elements, which is due to the enlargement of the electronic excitation energy of the Co,X-co-doped silicon.

Bonanza: An extremely large dust grain from a supernova

NASA Astrophysics Data System (ADS)

Gyngard, Frank; Jadhav, Manavi; Nittler, Larry R.; Stroud, Rhonda M.; Zinner, Ernst

2018-01-01

We report the morphology, microstructure, and isotopic composition of the largest SiC stardust grain known to have condensed from a supernova. The 25-μm diameter grain, termed Bonanza, was found in an acid-resistant residue of the Murchison meteorite. Grains of such large size have neither been observed around supernovae nor predicted to form in stellar environments. The large size of Bonanza has allowed the measurement of the isotopic composition of more elements in it than any other previous presolar grain, including: Li, B, C, N, Mg, Al, Si, S, Ca, Ti, Fe, and Ni. Bonanza exhibits large isotopic anomalies in the elements C, N, Mg, Si, Ca, Ti, Fe, and Ni typical of an astrophysical origin in ejecta of a Type II core-collapse supernova and comparable to those previously observed for other presolar SiC grains of type X. Additionally, we extracted multiple focused ion beam lift-out sections from different regions of the grain. Our transmission electron microscopy demonstrates that the crystalline order varies at the micrometer scale, and includes rare, higher order polytype domains (e.g., 15 R). Analyses with STEM-EDS show Bonanza contains a heterogeneous distribution of subgrains with sizes ranging from <10 nm to >100 nm of Ti(N, C); Fe, Ni-rich grains with variable Fe:Ni; and (Al, Mg)N. Bonanza also has the highest ever inferred initial 26Al/27Al ratio, consistent with its supernova origin. This unique grain affords us the largest expanse of data, both microstructurally and isotopically, to compare with detailed calculations of nucleosynthesis and dust condensation in supernovae.

Experiments of eliminating the destructive effects of excessive Fe inclusions for Al secondary products

NASA Astrophysics Data System (ADS)

Sun, D. Q.; Dai, G. H.; Geng, F.; Yang, K.

2017-02-01

Excessive Fe content in Al alloys caused the serious decline of mechanical properties, such as the ductility and impact toughness. Carried out the experiments of eliminating the destructive effects of excessive Fe content by flux-adding technology, which including removing a part of Fe content from Al scrap melt and modifying the morphology of Fe rich precipitates. The experimental results showed that, the ratio of removing Fe element was above 20%, and the morphology of Fe rich precipitates changed from Lamellar to bulk or lath precipitations under the process parameters: the fluxing-agents composed of borax, and MnCl2 (mixed by mass ratio of 1:1), and the adding amount of fluxing-agents was about 1.5%; thrown the fluxing-agents into the Al scrap melt by powder injection process and kept for 30 min.

Atomic Layer Deposition of Aluminum Sulfide: Growth Mechanism and Electrochemical Evaluation in Lithium-Ion Batteries

DOE PAGES

Meng, Xiangbo; Cao, Yanqiang; Libera, Joseph A.; ...

2017-10-01

This work describes the synthesis of aluminum sulfide (AlS x) thin films by atomic layer deposition (ALD) using tris(dimethylamido)aluminum and hydrogen sulfide. We employed a suite of in situ measurement techniques to explore the ALD AlS x growth mechanism, including quartz crystal microbalance, quadrupole mass spectrometry, and Fourier transform infrared spectroscopy. A variety of ex situ characterization techniques were used to determine the growth characteristics, morphology, elemental composition, and crystallinity of the resultant AlS x films. This study revealed that the AlS x growth was self-limiting in the temperature range 100–250 °C, and the growth per cycle decreased linearly withmore » increasing temperature from ~0.45 Å/cycle at 100 °C to ~0.1 Å/cycle at 250 °C. The AlSx films were amorphous in this temperature range. We conducted electrochemical testing to evaluate the ALD AlS x as a potential anode material for lithium-ion batteries (LIBs). Finally, the ALD AlS x exhibited reliable cyclability over 60 discharge–charge cycles with a sustainable discharge capacity of 640 mAh/g at a current density of 100 mA/g in the voltage window of 0.6–3.5 V.« less

Atomic Layer Deposition of Aluminum Sulfide: Growth Mechanism and Electrochemical Evaluation in Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Xiangbo; Cao, Yanqiang; Libera, Joseph A.

This work describes the synthesis of aluminum sulfide (AlS x) thin films by atomic layer deposition (ALD) using tris(dimethylamido)aluminum and hydrogen sulfide. We employed a suite of in situ measurement techniques to explore the ALD AlS x growth mechanism, including quartz crystal microbalance, quadrupole mass spectrometry, and Fourier transform infrared spectroscopy. A variety of ex situ characterization techniques were used to determine the growth characteristics, morphology, elemental composition, and crystallinity of the resultant AlS x films. This study revealed that the AlS x growth was self-limiting in the temperature range 100–250 °C, and the growth per cycle decreased linearly withmore » increasing temperature from ~0.45 Å/cycle at 100 °C to ~0.1 Å/cycle at 250 °C. The AlSx films were amorphous in this temperature range. We conducted electrochemical testing to evaluate the ALD AlS x as a potential anode material for lithium-ion batteries (LIBs). Finally, the ALD AlS x exhibited reliable cyclability over 60 discharge–charge cycles with a sustainable discharge capacity of 640 mAh/g at a current density of 100 mA/g in the voltage window of 0.6–3.5 V.« less

Asteroid orbital inversion using uniform phase-space sampling

NASA Astrophysics Data System (ADS)

Muinonen, K.; Pentikäinen, H.; Granvik, M.; Oszkiewicz, D.; Virtanen, J.

2014-07-01

We review statistical inverse methods for asteroid orbit computation from a small number of astrometric observations and short time intervals of observations. With the help of Markov-chain Monte Carlo methods (MCMC), we present a novel inverse method that utilizes uniform sampling of the phase space for the orbital elements. The statistical orbital ranging method (Virtanen et al. 2001, Muinonen et al. 2001) was set out to resolve the long-lasting challenges in the initial computation of orbits for asteroids. The ranging method starts from the selection of a pair of astrometric observations. Thereafter, the topocentric ranges and angular deviations in R.A. and Decl. are randomly sampled. The two Cartesian positions allow for the computation of orbital elements and, subsequently, the computation of ephemerides for the observation dates. Candidate orbital elements are included in the sample of accepted elements if the χ^2-value between the observed and computed observations is within a pre-defined threshold. The sample orbital elements obtain weights based on a certain debiasing procedure. When the weights are available, the full sample of orbital elements allows the probabilistic assessments for, e.g., object classification and ephemeris computation as well as the computation of collision probabilities. The MCMC ranging method (Oszkiewicz et al. 2009; see also Granvik et al. 2009) replaces the original sampling algorithm described above with a proposal probability density function (p.d.f.), and a chain of sample orbital elements results in the phase space. MCMC ranging is based on a bivariate Gaussian p.d.f. for the topocentric ranges, and allows for the sampling to focus on the phase-space domain with most of the probability mass. In the virtual-observation MCMC method (Muinonen et al. 2012), the proposal p.d.f. for the orbital elements is chosen to mimic the a posteriori p.d.f. for the elements: first, random errors are simulated for each observation, resulting in a set of virtual observations; second, corresponding virtual least-squares orbital elements are derived using the Nelder-Mead downhill simplex method; third, repeating the procedure two times allows for a computation of a difference for two sets of virtual orbital elements; and, fourth, this orbital-element difference constitutes a symmetric proposal in a random-walk Metropolis-Hastings algorithm, avoiding the explicit computation of the proposal p.d.f. In a discrete approximation, the allowed proposals coincide with the differences that are based on a large number of pre-computed sets of virtual least-squares orbital elements. The virtual-observation MCMC method is thus based on the characterization of the relevant volume in the orbital-element phase space. Here we utilize MCMC to map the phase-space domain of acceptable solutions. We can make use of the proposal p.d.f.s from the MCMC ranging and virtual-observation methods. The present phase-space mapping produces, upon convergence, a uniform sampling of the solution space within a pre-defined χ^2-value. The weights of the sampled orbital elements are then computed on the basis of the corresponding χ^2-values. The present method resembles the original ranging method. On one hand, MCMC mapping is insensitive to local extrema in the phase space and efficiently maps the solution space. This is somewhat contrary to the MCMC methods described above. On the other hand, MCMC mapping can suffer from producing a small number of sample elements with small χ^2-values, in resemblance to the original ranging method. We apply the methods to example near-Earth, main-belt, and transneptunian objects, and highlight the utilization of the methods in the data processing and analysis pipeline of the ESA Gaia space mission.

The cyclic oxidation resistance at 1200 C of beta-NiAl, FeAl, and CoAl alloys with selected third element additions

NASA Technical Reports Server (NTRS)

Barrett, C. A.; Titran, R. H.

1992-01-01

The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale.

Stardust Interstellar Preliminary Examination VII: Synchrotron X-Ray Fluorescence Analysis of Six Stardust Interstellar Candidates Measured with the Advanced Photon Source 2-ID-D Microprobe

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Anderson, David; Bastien, Ron K.; Brenker, Frank E.; Flynn, George J.; Frank, David; Gainsforth, Zack; Sandford, Scott A.; Simionovici, Alexandre S.; Zolensky, Michael E.

2014-01-01

The NASA Stardust spacecraft exposed an aerogel collector to the interstellar dust passing through the solar system. We performed X-ray fluorescence element mapping and abundance measurements, for elements 19 < or = Z < or = 30, on six "interstellar candidates," potential interstellar impacts identified by Stardust@Home and extracted for analyses in picokeystones. One, I1044,3,33, showed no element hot-spots within the designated search area. However, we identified a nearby surface feature, consistent with the impact of a weak, high-speed particle having an approximately chondritic (CI) element abundance pattern, except for factor-of-ten enrichments in K and Zn and an S depletion. This hot-spot, containing approximately 10 fg of Fe, corresponds to an approximately 350 nm chondritic particle, small enough to be missed by Stardust@Home, indicating that other techniques may be necessary to identify all interstellar candidates. Only one interstellar candidate, I1004,1,2, showed a track. The terminal particle has large enrichments in S, Ti, Cr, Mn, Ni, Cu, and Zn relative to Fe-normalized CI values. It has high Al/Fe, but does not match the Ni/Fe range measured for samples of Al-deck material from the Stardust sample return capsule, which was within the field-of-view of the interstellar collector. A third interstellar candidate, I1075,1,25, showed an Al-rich surface feature that has a composition generally consistent with the Al-deck material, suggesting that it is a secondary particle. The other three interstellar candidates, I1001,1,16, I1001,2,17, and I1044,2,32, showed no impact features or tracks, but allowed assessment of submicron contamination in this aerogel, including Fe hot-spots having CI-like Ni/Fe ratios, complicating the search for CI-like interstellar/interplanetary dust.

Stardust Interstellar Preliminary Examination VII: Synchrotron X-ray fluorescence analysis of six Stardust interstellar candidates measured with the Advanced Photon Source 2-ID-D microprobe

NASA Astrophysics Data System (ADS)

Flynn, George J.; Sutton, Steven R.; Lai, Barry; Wirick, Sue; Allen, Carlton; Anderson, David; Ansari, Asna; Bajt, SašA.; Bastien, Ron K.; Bassim, Nabil; Bechtel, Hans A.; Borg, Janet; Brenker, Frank E.; Bridges, John; Brownlee, Donald E.; Burchell, Mark; Burghammer, Manfred; Butterworth, Anna L.; Changela, Hitesh; Cloetens, Peter; Davis, Andrew M.; Doll, Ryan; Floss, Christine; Frank, David; Gainsforth, Zack; Grün, Eberhard; Heck, Philipp R.; Hillier, Jon K.; Hoppe, Peter; Hudson, Bruce; Huth, Joachim; Hvide, Brit; Kearsley, Anton; King, Ashley J.; Leitner, Jan; Lemelle, Laurence; Leroux, Hugues; Leonard, Ariel; Lettieri, Robert; Marchant, William; Nittler, Larry R.; Ogliore, Ryan; Ong, Wei Ja; Postberg, Frank; Price, Mark C.; Sandford, Scott A.; Tresseras, Juan-Angel Sans; Schmitz, Sylvia; Schoonjans, Tom; Silversmit, Geert; Simionovici, Alexandre; Sol, Vicente A.; Srama, Ralf; Stadermann, Frank J.; Stephan, Thomas; Sterken, Veerle; Stodolna, Julien; Stroud, Rhonda M.; Trieloff, Mario; Tsou, Peter; Tsuchiyama, Akira; Tyliszczak, Tolek; Vekemans, Bart; Vincze, Laszlo; von Korff, Joshua; Westphal, Andrew J.; Wordsworth, Naomi; Zevin, Daniel; Zolensky, Michael E.

2014-09-01

The NASA Stardust spacecraft exposed an aerogel collector to the interstellar dust passing through the solar system. We performed X-ray fluorescence element mapping and abundance measurements, for elements 19 ≤ Z ≤ 30, on six "interstellar candidates," potential interstellar impacts identified by Stardust@Home and extracted for analyses in picokeystones. One, I1044,3,33, showed no element hot-spots within the designated search area. However, we identified a nearby surface feature, consistent with the impact of a weak, high-speed particle having an approximately chondritic (CI) element abundance pattern, except for factor-of-ten enrichments in K and Zn and an S depletion. This hot-spot, containing approximately 10 fg of Fe, corresponds to an approximately 350 nm chondritic particle, small enough to be missed by Stardust@Home, indicating that other techniques may be necessary to identify all interstellar candidates. Only one interstellar candidate, I1004,1,2, showed a track. The terminal particle has large enrichments in S, Ti, Cr, Mn, Ni, Cu, and Zn relative to Fe-normalized CI values. It has high Al/Fe, but does not match the Ni/Fe range measured for samples of Al-deck material from the Stardust sample return capsule, which was within the field-of-view of the interstellar collector. A third interstellar candidate, I1075,1,25, showed an Al-rich surface feature that has a composition generally consistent with the Al-deck material, suggesting that it is a secondary particle. The other three interstellar candidates, I1001,1,16, I1001,2,17, and I1044,2,32, showed no impact features or tracks, but allowed assessment of submicron contamination in this aerogel, including Fe hot-spots having CI-like Ni/Fe ratios, complicating the search for CI-like interstellar/interplanetary dust.

Contributions of trace elements to the sea by small uncontaminated rivers: Effects of a water reservoir and a wastewater treatment plant.

PubMed

Álvarez-Vázquez, Miguel Ángel; Prego, Ricardo; Caetano, Miguel; De Uña-Álvarez, Elena; Doval, Maryló; Calvo, Susana; Vale, Carlos

2017-07-01

Trace element contributions from small rivers to estuaries is an issue barely addressed in the literature. In this work, freshwater flowing into the Ria of Cedeira (NW Iberian Peninsula) was studied during a hydrological year through the input from three rivers, one considered uncontaminated (the Das-Mestas River), a second affected by urban treated wastewater discharges (the Condomiñas River), and the third containing a water reservoir for urban supply (the Forcadas River). With the objective of assessing the possible influence of human pressure, the annual yields for selected trace elements (Al, Fe, As, Cd, Co, Cr, Cu, Mn, Mo, Ni and Pb) were estimated and compared by normalizing by basin surface. Both dissolved and particulate transported elements were considered. After the data treatment and analysis it can be highlighted that: (i) the Das Mestas River is suitable to be included between the short European pristine baseline of small rivers, at least regarding the transported trace elements; (ii) natural enrichments were identified associated to the lithology of the basin in the Das-Mestas River (i.e. As) and in the Condomiñas River (i.e. Co, Cr and Ni); this fact highlights the importance of considering the local background for a proper assessment; (iii) the impoundment in the Forcadas River is related with a general decrease, even depletion, of the particulate and dissolved transported trace elements, except Mn; (iv) the discharge of sewage to the Condomiñas River is increasing the inputs to the ria of some trace elements in the particulate phase (i.e. Al, Cu and Pb). Both observed human-induced changes can be regarded as typical disturbances of trace element contributions from small rivers to estuaries. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methods for separating oxygen from oxygen-containing gases

DOEpatents

Mackay, Richard; Schwartz, Michael; Sammells, Anthony F.

2000-01-01

This invention provides mixed conducting metal oxides particularly useful for the manufacture of catalytic membranes for gas-phase oxygen separation processes. The materials of this invention have the general formula: A.sub.x A'.sub.x A".sub.2-(x+x') B.sub.y B'.sub.y B".sub.2-(y+y') O.sub.5+z ; where x and x' are greater than 0; y and y' are greater than 0; x+x' is less than or equal to 2; y+y' is less than or equal to 2; z is a number that makes the metal oxide charge neutral; A is an element selected from the f block lanthanide elements; A' is an element selected from Be, Mg, Ca, Sr, Ba and Ra; A" is an element selected from the f block lanthanides or Be, Mg, Ca, Sr, Ba and Ra; B is an element selected from the group consisting of Al, Ga, In or mixtures thereof; and B' and B" are different elements and are independently selected from the group of elements Mg or the d-block transition elements. The invention also provides methods for oxygen separation and oxygen enrichment of oxygen deficient gases which employ mixed conducting metal oxides of the above formula. Examples of the materials used for the preparation of the membrane include A.sub.x Sr.sub.x' B.sub.y Fe.sub.y' Co.sub.2-(y+y') O.sub.5+z, where x is about 0.3 to about 0.5, x' is about 1.5 to about 1.7, y is 0.6, y' is between about 1.0 and 1.4 and B is Ga or Al.

The use of olive tree (Olea europaea L.) leaves as a bioindicator for environmental pollution in the Province of Aydın, Turkey.

PubMed

Turan, Dilek; Kocahakimoglu, Cemre; Kavcar, Pınar; Gaygısız, Handan; Atatanir, Levent; Turgut, Cafer; Sofuoglu, Sait C

2011-03-01

In this study, olive tree leaves, collected from 50 sampling sites throughout the Province of Aydın, Turkey, were used to estimate level of pollution by measuring Al, As, B, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, and Zn concentrations and calculating pollution factor (PF) values. After sample preparation, collected leaves were microwave digested, and extracts were analyzed by an inductively coupled plasma-mass spectrometer. The maximum PF values were ≥10 for a number of elements ranging from 11-13 (Al, As, Cr, Fe, Mn, Ni) to >100 for Cu, Li, and Na. Urban-rural and roadside-nonroadside concentration comparisons showed that some of the elements (As, Cu, and Pb) were at significantly higher levels on urban and/or roadside sampling sites. Correlations and factor analysis showed that there may be common sources for some elements, which included several soil types and anthropogenic activities. Based on the results of the statistical source apportionment, possible sources were narrowed down with help of the constructed elemental concentration maps. In conclusion, utilization of olive tree leaves for biomonitoring and assessment of environmental pollution was shown to be possible in the Mediterranean region where they are indigenous and cultivated.

Reconnaissance geochemical survey of Al Jurdhawiyah and Wadi al Jarir quadrangles, sheets 25/42 D and 25/42 C, Kingdom of Saudia Arabia

USGS Publications Warehouse

Samater, Rashid M.

1983-01-01

A reconnaissance wadi-sediment geochemical survey was conducted in the Al Jurdhawiyah (sheet 28/42 D) and Wadi al Jarir (sheet 2G/42 C) quadrangles in order to identify anomalies potentially related to mineralized rock. Sieved bulk-sediment fractions and pan concentrates were created from the original samples collected from wadis in the two quadrangles. A semiquantitative 30-element spectrographic analysis was completed on both the sieved bulk-sediment fraction and the pan concentrate of each sample. The results were statistically analyzed in an attempt to identify anomalous regions. Anomaly threshold values were calculated for most elements; the threshold value of an element in a data set is defined as the geometric mean value plus two standard deviations. The Bald al Jimalah West tin-tungsten deposit (MODS 02661) in the southern part of the Al Jurdhawiyah quadrangle was identified by one pan-concentrate sample containing anomalous concentrations of tin and tungsten. Samples near the Bald al Jimalah East ancient lead-zinc-silver mines (MODS 00960) contain strongly anomalous concentrations of tin and lead and to a lesser extent of tungsten and copper. Both of these regions and other regions containing anomalous concentrations of certain elements are recommended for additional studies. A comparison of results obtained from sieved bulk-sediment fractions and pan concentrates indicates that the latter is the better medium for these geochemical investigations.

Development of phase analysis methods of impurity elements in alloys based on iron and nickel

NASA Astrophysics Data System (ADS)

Andreeva, N. A.; Anuchkin, S. N.; Volchenkova, V. A.; Kazenas, E. K.; Penkina, T. N.; Fomina, A. A.

2018-04-01

Using the method of AES with ICP, new methods have been developed for quantifying the content of various forms of existence of impurity elements: Al-Al2O3; Zr-ZrO2 in alloys based on iron (Fe-Sn) and nickel (Ni-Sn). Open systems were used to dissolve Al and Zr. To translate difficult-to-open aluminum oxides (corundum) and zirconium oxide (baddeleyite) into the solution, accelerated techniques were developed using the microwave system Mars 5. To confirm the completeness of the dissolution of oxides, a classical scheme of alloy fusion with alkali metal salts was used. Optimal analytical parameters for determining the elements: Al and Zr were chosen. The influence of matrix elements (iron and nickel) and methods of its elimination were studied. This made it possible to determine the elements in a wide concentration range from 1 • 10-3 to n% Al and from 1 • 10-4 to n% Zr without preliminary separation of the matrix with good metrological characteristics. The relative standard deviation (Sr) does not exceed 0,2. The separate determination of the contents of aluminum and aluminium oxide in the model melt of Fe-Sn-Al2O3 and zirconium and zirconium oxide in the Ni-Sn-ZrO2 model melt allowed us to estimate the number of nanoparticles participating in the heterophase interaction with tin and retired to the interface in the form of ensembles and the number of nanoparticles present in the melt and affecting the crystallization process and the structure of the metal.

Trace elements and radon in groundwater across the United States, 1992-2003

USGS Publications Warehouse

Ayotte, Joseph D.; Gronberg, Jo Ann M.; Apodaca, Lori E.

2011-01-01

Trace-element concentrations in groundwater were evaluated for samples collected between 1992 and 2003 from aquifers across the United States as part of the U.S. Geological Survey National Water-Quality Assessment Program. This study describes the first comprehensive analysis of those data by assessing occurrence (concentrations above analytical reporting levels) and by comparing concentrations to human-health benchmarks (HHBs). Data from 5,183 monitoring and drinking-water wells representing more than 40 principal and other aquifers in humid and dry regions and in various land-use settings were used in the analysis. Trace elements measured include aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), uranium (U), vanadium (V), and zinc (Zn). Radon (Rn) gas also was measured and is included in the data analysis. Climate influenced the occurrence and distribution of trace elements in groundwater whereby more trace elements occurred and were found at greater concentrations in wells in drier regions of the United States than in humid regions. In particular, the concentrations of As, Ba, B, Cr, Cu, Mo, Ni, Se, Sr, U, V, and Zn were greater in the drier regions, where processes such as chemical evolution, ion complexation, evaporative concentration, and redox (oxidation-reduction) controls act to varying degrees to mobilize these elements. Al, Co, Fe, Pb, and Mn concentrations in groundwater were greater in humid regions of the United States than in dry regions, partly in response to lower groundwater pH and (or) more frequent anoxic conditions. In groundwater from humid regions, concentrations of Cu, Pb, Rn, and Zn were significantly greater in drinking-water wells than in monitoring wells. Samples from drinking-water wells in dry regions had greater concentrations of As, Ba, Pb, Li, Sr, V, and Zn, than samples from monitoring wells. In humid regions, however, concentrations of most trace elements were greater in monitoring wells than in drinking-water wells; the exceptions were Cu, Pb, Zn, and Rn. Cu, Pb, and Zn are common trace elements in pumps and pipes used in the construction of drinking-water wells, and contamination from these sources may have contributed to their concentrations. Al, Sb, Ba, B, Cr, Co, Fe, Mn, Mo, Ni, Se, Sr, and U concentrations were all greater in monitoring wells than in drinking-water wells in humid regions. Groundwater from wells in agricultural settings had greater concentrations of As, Mo, and U than groundwater from wells in urban settings, possibly owing to greater pH in the agricultural wells. Significantly greater concentrations of B, Cr, Se, Ag, Sr, and V also were found in agricultural wells in dry regions. Groundwater from dry-region urban wells had greater concentrations of Co, Fe, Pb, Li, Mn, and specific conductance than groundwater from agricultural wells. The geologic composition of aquifers and aquifer geochemistry are among the major factors affecting trace-element occurrence. Trace-element concentrations in groundwater were characterized in aquifers from eight major groups based on geologic material, including (1) unconsolidated sand and gravel; (2) glacial unconsolidated sand and gravel; (3) semiconsolidated sand; (4) sandstone; (5) sandstone and carbonate rock; (6) carbonate rock; (7) basaltic and other volcanic rock; and (8) crystalline rock. The majority of groundwater samples and the largest percentages of exceedences of HHBs were in the glacial and nonglacial unconsolidated sand and gravel aquifers; in these aquifers, As, Mn, and U are the most common trace elements exceeding HHBs. Overall, 19 percent of wells (962 of 5,097) exceeded an HHB for at least one trace element. The trace elements with HHBs included in this summary were Sb, As, Ba, Be, B, Cd, Cr,

The Facade of Stability in Assisted Living

PubMed Central

2014-01-01

Objectives. The study sought to identify the varied types of change arising from internal and external influences in assisted living (AL) settings, expanding upon the literature’s limited focus on resident decline and staff turnover and clarifying the importance of changes to life and work there. Method. This analysis employed qualitative interviews and observations from 4 studies involving 17 ALs to identify elements of change largely absent from the literature. Case material identified by the research team members relating to persons, groups, and settings exemplifying typical changes, as well as variations across settings, are presented. Results. Multiple domains of AL change were identified, to include those in: (a) the external economic or competitive environments; (b) ownership, management, or key personnel; and (c) physical health or cognition of the aggregate resident population. In many cases, the changes influenced residents’ satisfaction and perceived fit with the AL environment. Discussion. Change of many types is a regular feature of AL; many changes alter routines or daily life; raise concerns of staff, residents, or families; or modify perceptions of residential normalcy. Environmental gerontology should more often extend the environment to include the social and interpersonal characteristics of collective living sites for elders. PMID:24642968

Process recognition in multi-element soil and stream-sediment geochemical data

USGS Publications Warehouse

Grunsky, E.C.; Drew, L.J.; Sutphin, D.M.

2009-01-01

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on the spatial separation of the stream-sediment and soil samples, some elements are more highly correlated than others. Crown Copyright ?? 2009.

Reconstructing paleoceanographic conditions in the westernmost Mediterranean during the last 4.000 yr: tracking rapid climate variability

NASA Astrophysics Data System (ADS)

Nieto-Moreno, V.; Martínez-Ruiz, F.; Jiménez-Espejo, F. J.; Gallego-Torres, D.; Rodrigo-Gámiz, M.; Sakamoto, T.; Böttcher, M.; García-Orellana, J.; Ortega-Huertas, M.

2009-04-01

The westernmost Mediterranean (Alboran Sea basin) is a key location for paleoceanographic and paleoclimatic reconstructions since high sedimentation rates provide ultra high-resolution records at centennial and millennial scales. Here, we present a paleoenvironmental reconstruction for the last 4000 yr, which is based on a multi-proxy approach that includes major and trace element-content fluctuations and mineral composition of marine sediments. The investigated materials correspond to several gravity and box cores recovered in the Alboran Sea basin during different oceanographic cruises (TTR-14 and TTR-17), which have been sampled at very high resolution. Comparative analysis of these cores allows establishing climate oscillations at centennial to millennial scales. Although relatively more attention have been devoted to major climate changes during the last glacial cycle, such as the Last Glacial Maximun, deglaciation and abrupt cooling events (Heinrich and Younger Dryas), the late Holocene has also been punctuated by significant rapid climate variability including polar cooling, aridity and changes in the intensity of the atmospheric circulation. These climate oscillations coincide with significant fluctuations in chemical and mineral composition of marine sediments. Thus, bulk and clay mineralogy, REE composition and Rb/Al, Zr/Al, La/Lu ratios provide information on the sedimentary regime (eolian-fluvial input and source areas), Ba-based proxies on fluctuations in marine productivity and redox sensitive elements on oxygen conditions at time of deposition. A decrease in fluvial-derived elements/minerals (e.g., Rb, detrital mica) takes places during the so-called Late Bronze Age-Iron Age, Dark Age, and Little Ice Age Period. Meanwhile an increase is evidenced during the Medieval Warm Period and the Roman Humid Period. This last trend runs parallel to a decline of element/minerals of typical eolian source (Zr, kaolinite) with the exception of the Roman Humid Period where Zr/Al ratio increases. These climate oscillations (wet and dry periods) are also accompanied by changes in marine productivity rates, as suggested by the Ba/Al ratio. Additionally, anthropic contribution during the Industrial Period is also evidenced by a significant increase in Pb content in most recent sediments. Acknowledges: Projects Marcal CGL2006-13327-C04-04, Sagas CTM2005-08071-C03-01, Ministerio MARM 200800050084447, RNM 0179, CSD2006-00041.

Metal/Silicate Partitioning of P, Ga, and W at High Pressures and Temperatures: Dependence on Silicate Melt Composition

NASA Technical Reports Server (NTRS)

Bailey, Edward; Drake, Michael J.

2004-01-01

The distinctive pattern of element concentrations in the upper mantle provides essential evidence in our attempts to understand the accretion and differentiation of the Earth (e.g., Drake and Righter, 2002; Jones and Drake, 1986; Righter et al., 1997; Wanke 1981). Core formation is best investigated through use of metal/silicate partition coefficients for siderophile elements. The variables influencing partition coefficients are temperature, pressure, the major element compositions of the silicate and metal phases, and oxygen fugacity. Examples of studies investigating the effects of these variables on partitioning behavior are: composition of the metal phase by Capobianco et al. (1999) and Righter et al. (1997); silicate melt composition by Watson (1976), Walter and Thibault (1995), Hillgren et al. (1996), Jana and Walker (1997), and Jaeger and Drake (2000); and oxygen fugacity by Capobianco et al. (1999), and Walter and Thibault (1995). Here we address the relative influences of silicate melt composition, pressure and temperature.

Natural and anthropogenic controls on sediment composition of an arid coastal environment: Sharm Obhur, Red Sea, Saudi Arabia.

PubMed

Ghandour, I M; Basaham, A S; Basaham, S; Al-Washmi, H A; Al-Washmi, A; Masuda, H

2014-03-01

The present study investigated the natural and anthropogenic processes that control the composition of the bottom sediments of Sharm Obhur, Red Sea. Mineralogical analysis using XRD indicated that the sediments consist of carbonate and non-carbonate minerals. Elemental interrelationships allowed differentiating two groups of elements of different sources and origin. Elements that are in the same group are positively correlated, while they correlate negatively with elements of the other group. The first group includes silicon, Al, Fe, Mn, Mg, vanadium (V), chromium (Cr), Co, Ni, Cu, and Zn, whereas the other group includes Ca, Sr, and CaCO3. The highest concentration levels of the first group and the highest content of non-carbonate minerals were obtained from the sediments near the head of the sharm (zone A), whereas the sediments near the mouth of the sharm (zone B) yielded high concentrations of second group and carbonate minerals. Metal enrichment and contamination factors and pollution load index were calculated. The values of these indices differentiate two groups of metals: lithogenic and non-lithogenic. Except for lead (Pb) at one sampling site, metals in zone A sediments are of lithogenic source, supplied to the sharm either naturally by aeolian transportation and through Wadi Al-Kuraa'a during rare but major floods or by human activities such as dumping and shore protection. Non-lithogenic Cr, Pb, V, and Mn were documented from some sampling sites in zone B, and their occurrences are related to waste disposal and fossil fuel combustion.

Evaluation of frictional melting on the basis of trace element analyses of fault rocks

NASA Astrophysics Data System (ADS)

Ishikawa, T.; Ujiie, K.

2016-12-01

Pseudotachylytes (solidified frictional melts produced during seismic slip) found in exhumed accretionary complexes are considered to have formed originally at seismogenic depths, and help our understanding of the dynamics of earthquake faulting in subduction zones. The frictional melting should affect rock chemistry. Actually, major element compositions of unaltered pseudotachylyte matrix in the Shimanto accretionary complex are reported to be similar to that of illite, implying disequilibrium melting in the slip zone (Ujiie et al., 2007). Bulk-rock trace element analyses of the pseudotachylyte-bearing fault rocks also revealed their shift to the clay-mineral-like compositions (Honda et al., 2011). Toward better understanding of the frictional melting using chemical means, we carried out detailed major and trace element analyses for pseudotachylyte-bearing dark veins and surrounding host rocks from the Mugi area of the Shimanto accretionary complex (Ujiie et al., 2007). About one milligram each of samples was collected from a rock chip along the microstructure by using the PC-controlled micro-drilling apparatus, and then analyzed by ICP-MS. Host rocks showed a series of compositional trends controlled by mixing of detrital sedimentary components. Unaltered part of the pseudotachylyte vein, on the other hand, showed striking enrichment of fluid-immobile trace elements, consistent with selective melting of fine-grained, clay-rich matrix of the fault rock. Importantly, completely altered parts of the dark veins exhibit essentially the same characteristics as the unaltered part, indicating that the trace element composition of the pseudotachylyte is well preserved even after considerable alteration in the later stages. These results demonstrate that trace element and structural analyses are useful to detect preexistence of pseudotachylytes resulting from selective frictional melting of clay minerals. It has been controversial that pseudotachylytes are rarely formed or rarely preserved. Trace element analyses on clay-rich localized slipping zones shed light on this topic. References: Ujiie et al. (2007) J. Struct. Geol. 29, 599-613; Honda et al. (2011) GRL 38, L06310.

Synergistic effect of alloying elements doping and external pressure on the elastic property of Ni{sub 3}Al: A first-principles study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, C., E-mail: lichun@nwpu.edu.cn; Shang, J.; Yue, Z.

2015-07-15

In this paper, the basic electronic structures and elastic properties of Ni{sub 3}Al doping with alloying elements (Re, Cr, and Mo) under different pressures have been investigated using first-principles calculations based on density functional theory. It is shown that both alloying elements and external applied pressure contribute positively to the elastic properties of Ni{sub 3}Al, and the configurations of the compounds remain almost unchanged. The calculated elastic constants and moduli increase linearly with the pressure increasing from 0 and 40 GPa. Among the alloying elements studied in the present work, Re exhibits the most significant effect compared with the othermore » elements, showing its practical importance. Especially, if both alloying elements doping and pressure effects are considered simultaneously, which has not been considered previously, the studied compounds exhibit an even better elastic property than the simple superposition of the two influences. Such synergistic effect demonstrates promising applications of Ni-based single crystal superalloys in possible extreme mechanical environments.« less

Ancient crustal components in the Fra Mauro breccias

NASA Technical Reports Server (NTRS)

Shervais, J. W.; Taylor, L. A.; Laul, J. C.

1983-01-01

Texturally pristine clasts preserve primary petrographic relationships and mineral compositions, yielding insights into igneous processes of the early lunar crust that cannot be gained from highly shocked and brecciated 'chemically pristine' samples. The use of texture as a prime criterion allows for expansion of the data base derived solely from chemical criteria, and provides complementary data. Texturally pristine clasts from the Apollo 14 site studied here include anorthosite, troctolites, gabbronorites, and basalts. Alkali anorthosites are plagioclase orthocumulates and may form by flotation in Mg-suite plutons. Ferroan anorthosite was cataclastically deformed and metamorphosed to granulite facies. Troctolites include both 01 + Plg and 01 + En + Plg cumulates. Major and trace element analyses of two troctolites reveal 'eastern' geochemical affinities that contrast other 'western' troctolites. Gabbronorites are Pig + Plg + or - Sp cumulates whose parent magmas may range from high-Al to intermediate-Ti mare basalt. At least three varieties of mare basalt are found at Apollo 14: high-Al, low-Ti; low-Al, intermediate-Ti; and low-Al, Ti VHK basalt. VHK (Very High Potassium) basalt is a new variety indigenous to Apollo 14.

An Integer Optimization Approch To A Probabilistic Reserve Site Selection Problem

Treesearch

Robert G. Haight; Charles S. Revelle; Stephanie A. Snyder

2000-01-01

Human economic and agricultural activities contribute to the endangerment of over 900 species that are currently listed or proposed for listing under the federal Endangered Species Act in the United States (Dobson et al. 1997). One approach to conserving the elements of biological diversity--including plants, animals, and ecological communities--is to establish and...

Microembossing of ultrafine grained Al: microstructural analysis and finite element modelling

NASA Astrophysics Data System (ADS)

Qiao, Xiao Guang; Bah, Mamadou T.; Zhang, Jiuwen; Gao, Nong; Moktadir, Zakaria; Kraft, Michael; Starink, Marco J.

2010-10-01

Ultra-fine-grained (UFG) Al-1050 processed by equal channel angular pressing and UFG Al-Mg-Cu-Mn processed by high-pressure torsion (HPT) were embossed at both room temperature and 300 °C, with the aim of producing micro-channels. The behaviour of Al alloys during the embossing process was analysed using finite element modelling. The cold embossing of both Al alloys is characterized by a partial pattern transfer, a large embossing force, channels with oblique sidewalls and a large failure rate of the mould. The hot embossing is characterized by straight channel sidewalls, fully transferred patterns and reduced loads which decrease the failure rate of the mould. Hot embossing of UFG Al-Mg-Cu-Mn produced by HPT shows a potential of fabrication of microelectromechanical system components with micro channels.

Characterization of an internal ribosomal entry segment within the 5' leader of avian reticuloendotheliosis virus type A RNA and development of novel MLV-REV-based retroviral vectors.

PubMed

López-Lastra, M; Gabus, C; Darlix, J L

1997-11-01

The murine leukemia virus (MLV)-related type C viruses constitute a major class of retroviruses that includes numerous endogenous and exogenous mammalian viruses and the related avian spleen necrosis virus (SNV). The MLV-related viruses possess a long and multifunctional 5' untranslated leader involved in key steps of the viral life cycle--splicing, translation, RNA dimerization, encapsidation, and reverse transcription. Recent studies have shown that the 5' leader of Friend murine leukemia virus and Moloney murine leukemia virus can direct cap independent translation of gag precursor proteins (Berlioz et al., 1995; Vagner et al., 1995b). These data, together with structural homology studies (Koning et al., 1992), prompted us to undertake a search for new internal ribosome entry segment (IRES) of retroviral origin. Here we describe an IRES element within the 5' leader of avian reticuloendotheliosis virus type A (REV-A) genomic RNA. Data show that the REV-A 5' IRES element maps downstream of the packaging/dimerization (E/DLS) sequence (Watanabe and Temin, 1982; Darlix et al., 1992) and the minimal IRES sequence appears to be within a 129 nt fragment (nucleotides 452-580) of the 5' leader, immediately upstream of the gag AUG codon. The REV-A IRES has been successfully utilized in the construction of novel high titer MLV-based retroviral vectors, containing one or more IRES elements of retroviral origin. These retroviral constructs, which represent a starting point for the design of novel vectors suitable for gene therapy, are also of interest as a model system of internal translation initiation and its possible regulation during development, cancer, or virus infection.

Distribution and environmental assessment of trace elements contamination of water, sediments and flora from Douro River estuary, Portugal.

PubMed

Ribeiro, C; Couto, C; Ribeiro, A R; Maia, A S; Santos, M; Tiritan, M E; Pinto, E; Almeida, A A

2018-10-15

The present study evaluated the content and distribution of several trace elements (Li, Be, Al, V, Cr, Co, Ni, Cu, Zn, Se, Mo, Ag, Cd, Sb, Ba, Tl, Pb, and U) in the Douro River estuary. For that, three matrices were collected (water, sediments and native local flora) to assess the extent of contamination by these elements in this estuarine ecosystem. Results showed their occurrence in estuarine water and sediments, but significant differences were recorded on the concentration levels and pattern of distribution among both matrices and sampling points. Generally, the levels of trace elements were higher in the sediments than in the respective estuarine water. Nonetheless, no correlation among trace elements was determined between water and sediments, except for Cd. Al was the trace element found at highest concentration at both sediments and water followed by Zn. Pollution indices such as geo-accumulation (I geo ), enrichment factor (EF) and contamination factor (CF) were determined to understand the levels and sources of trace elements pollution. I geo showed strong contamination by anthropogenic activities for Li, Al, V, Cr, Ni, Cu, Zn, Ba and Pb at all sampling points while EF and CF demonstrated severe enrichment and contamination by Se, Sb and Pb. Levels of trace elements were compared to acceptable values for aquatic organisms and Sediment Quality Guidelines. The concentration of some trace elements, namely Al, Pb and Cu, were higher than those considered acceptable, with potential negative impact on local living organisms. Nevertheless, permissible values for all trace elements are still not available, demonstrating that further studies are needed in order to have a complete assessment of environmental risk. Furthermore, the occurrence and possible accumulation of trace elements by local plant species and macroalgae were investigated as well as their potential use as bioindicators of local pollution and for phytoremediation purposes. Copyright © 2018 Elsevier B.V. All rights reserved.

Phase transformation and magnetic properties of MnAl powders prepared by elemental-doping and salt-assisted ball milling

NASA Astrophysics Data System (ADS)

Qian, Hui-Dong; Si, Ping-Zhan; Choi, Chul-Jin; Park, Jihoon; Cho, Kyung Mox

2018-05-01

The effects of elemental doping of Si and Fe on the ɛ→τ phase transformation and the magnetic properties of MnAl were studied. The magnetic powders of Si- and Fe-doped MnAl were prepared by using induction melting followed by water-quenching, annealing, and salt-assisted ball-milling. The Fe-doped MnAl powders are mainly composed of the L10-structured τ-phase, while the Si-doped MnAl are composed of τ-phase and a small fraction of γ2- and β-phases. A unique thin leaves-like morphology with thickness of several tens of nanometers and diameter size up to 500 nm were observed in the Si-doped MnAl powders. The Fe-doped MnAl powders show irregular shape with much larger dimensions in the range from several to 10 μm. The morphology difference of the samples was ascribed to the variation of the mechanical properties affected by different doping elements. The phase transformation temperatures of the ɛ-phase of the samples were measured. The doping of Fe decreases the onset temperature of the massive phase transformation in MnAl, while the Si-doping increases the massive phase transformation temperature. Both Fe and Si increase the Curie temperature of MnAl. A substantially enhanced coercivity up to 0.45 T and 0.42 T were observed in the ball-milled MnAl powders doped with Si and Fe, respectively.

Abundances in metal-rich stars. Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] > 0.10 dex

NASA Astrophysics Data System (ADS)

Feltzing, S.; Gustafsson, B.

1998-04-01

We have derived elemental abundances of O, Na, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, Co, Ni as well as for a number of s-elements for 47 G and K dwarf, with [Me/H]>0.1 dex. The selection of stars was based on their kinematics as well as on their uvby-beta photometry. One sample of stars on rather eccentric orbits traces the chemical evolution interior to the solar orbit and another, on circular orbits, the evolution around the solar orbit. A few Extreme Population I stars were included in the latter sample. The stars have -0.1 dex < [Fe/H] < 0.42 dex. The spectroscopic [Fe/H] correlate well with the [Me/H] derived from uvby-beta photometry. We find that the elemental abundances of Mg, Al, Si, Ca, Ti, Cr and Ni all follow [Fe/H]. Our data put further constraints on models of galactic chemical evolution, in particular of Cr, Mn and Co which have not previously been studied for dwarf stars with [Me/H] >0.1 dex. The increase in [Na/Fe] and [Al/Fe] as a function of [Fe/H] found previously by \\cite[Edvardsson et al. (1993a)]{Edv93} has been confirmed for [Na/Fe]. This upturning relation, and the scatter around it, are shown not to be due to a mixture of populations with different mean distances to the galactic centre. We do not confirm the same trend for aluminium, which is somewhat surprising since both these elements are thought to be produced in the same environments in the pre-supernova stars. Nor have we been able to trace any tendency for relative abundances of O, Si, and Ti relative to Fe to vary with the stellar velocities, i.e. the stars present mean distance to the galactic centre. These results imply that there is no significant difference in the chemical evolution of the different stellar populations for stars with [Me/H]>0.1 dex. We find that [O/Fe] continue to decline with increasing [Fe/H] and that oxygen and europium correlate well. However [Si/Fe] and [Ca/Fe] seem to stay constant. A real (``cosmic'') scatter in [Ti/Fe] at given [Fe/H] is suggested as well as a decreasing abundance of the s-elements relative to iron for the most metal-rich dwarf stars. We discuss our results in the context of recent models of galactic chemical evolution. In our sample we have included a few very metal rich stars, sometimes called SMR (super metal rich) stars. We find these stars to be among the most iron-rich in our sample but far from as metal-rich as indicated by their photometric metallicities. SMR stars on highly eccentric orbits, alleged to trace the evolution of the chemical evolution in the galactic Bulge, have previously been found overabundant in O, Mg and Si. We have included three such stars from the study by \\cite[Barbuy & Grenon (1990)]{Bar90}. We find them to be less metal rich and the other elemental abundances remain puzzling. Detailed spectroscopic abundance analyses of K dwarf stars are rare. Our study includes 5 K dwarf stars and has revealed what appears to be a striking example of overionization. The overionization is especially prominent for Ca, Cr and Fe. The origin of this apparent overionization is not clear and we discuss different explanations in some detail. Based on observations at the McDonald Observatory.

Simultaneous increase in strength and ductility by decreasing interface energy between Zn and Al phases in cast Al-Zn-Cu alloy.

PubMed

Han, Seung Zeon; Choi, Eun-Ae; Park, Hyun Woong; Lim, Sung Hwan; Lee, Jehyun; Ahn, Jee Hyuk; Hwang, Nong-Moon; Kim, Kwangho

2017-09-22

Cast-Al alloys that include a high amount of the second element in their matrix have comparatively high strength but low ductility because of the high volume fraction of strengthening phases or undesirable inclusions. Al-Zn alloys that have more than 30 wt% Zn have a tensile strength below 300 MPa, with elongation under 5% in the as-cast state. However, we found that after substitution of 2% Zn by Cu, the tensile strength of as-cast Al-Zn-Cu alloys was 25% higher and ductility was four times higher than for the corresponding Al-35% Zn alloy. Additionally, for the Al-43% Zn alloy with 2% Cu after 1 h solution treatment at 400 °C and water quenching, the tensile strength unexpectedly reached values close to 600 MPa. For the Al-33% Zn alloy with 2% Cu, the tensile strength was 500 MPa with 8% ductility. The unusual trends of the mechanical properties of Al-Zn alloys with Cu addition observed during processing from casting to the subsequent solution treatment were attributed to the precipitation of Zn in the Al matrix. The interface energy between the Zn particles and the Al matrix decreased when using a solution of Cu in Zn.

Multi-elemental imaging of paraffin-embedded human samples by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Moncayo, S.; Trichard, F.; Busser, B.; Sabatier-Vincent, M.; Pelascini, F.; Pinel, N.; Templier, I.; Charles, J.; Sancey, L.; Motto-Ros, V.

2017-07-01

Chemical elements play central roles for physiological homeostasis in human cells, and their dysregulation might lead to a certain number of pathologies. Novel imaging techniques that improve the work of pathologists for tissue analysis and diagnostics are continuously sought. We report the use of Laser-Induced Breakdown Spectroscopy (LIBS) to perform multi-elemental images of human paraffin-embedded skin samples on the entire biopsy scale in a complementary and compatible way with microscope histopathological examination. A specific instrumental configuration is proposed in order to detect most of the elements of medical interest (i.e. P, Al, Mg, Na, Zn, Si, Fe, and Cu). As an example of medical application, we selected and analysed skin biopsies, including healthy skin tissue, cutaneous metastasis of melanoma, Merkel-cell carcinoma and squamous cell carcinoma. Clear distinctions in the distribution of chemical elements are observed from the different samples investigated. This study demonstrates the high complementarity of LIBS elemental imaging with conventional histopathology, opening new opportunities for any medical application involving metals.

Background levels of some major, trace, and rare earth elements in indigenous plant species growing in Norway and the influence of soil acidification, soil parent material, and seasonal variation on these levels.

PubMed

Gjengedal, Elin; Martinsen, Thomas; Steinnes, Eiliv

2015-06-01

Baseline levels of 43 elements, including major, trace, and rare earth elements (REEs) in several native plant species growing in boreal and alpine areas, are presented. Focus is placed on species metal levels at different soil conditions, temporal variations in plant tissue metal concentrations, and interspecies variation in metal concentrations. Vegetation samples were collected at Sogndal, a pristine site in western Norway, and at Risdalsheia, an acidified site in southernmost Norway. Metal concentrations in the different species sampled in western Norway are compared with relevant literature data from Norway, Finland, and northwest Russia, assumed to represent natural conditions. Except for aluminium (Al) and macronutrients, the levels of metals were generally lower in western Norway than in southern Norway and may be considered close to natural background levels. In southern Norway, the levels of cadmium (Cd) and lead (Pb) in particular appear to be affected by air pollution, either by direct atmospheric supply or through soil acidification. Levels of some elements show considerable variability between as well as within plant species. Calcium (Ca), magnesium (Mg), and potassium (K) are higher in most species at Sogndal compared to Risdalsheia, despite increased extractable concentrations in surface soil in the south, probably attributed to different buffer mechanisms in surface soil. Antagonism on plant uptake is suggested between Ca, Mg, and K on one hand and Al on the other. Tolerance among calcifuges to acid conditions and a particular ability to detoxify or avoid uptake of Al ions are noticeable for Vaccinium vitis-idaea.

Geochemistry and mineralogy of fly-ash from the Mae Moh lignite deposit, Thailand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hart, B.R.; Powell, M.A.; Fyfe, W.S.

The concentration of 21 elements in fly ash from three boilers (75 MW, 150 MW, and 300 MW) at the EGAT power plant, Mae Moh, Thailand, were determined by INAA. The concentration of 10 major elements was determined by XRF. As, Co, Cr, Ni, Mo, and Sb generally increase in concentration going from bottom ash (BA) through the sequence of electrostatic precipitator ashes (ESPA) and reach maxima of As (352 ppm), Co (45 ppm), Cr (105 ppm), Mo (32 ppm), Ni (106 ppm), and Sb (15 ppm) in the ESPA. Ce, Cs, Fe, Hf, La, Sc, Ta, Tb, and Ybmore » did not exhibit concentration trends or are variable except in the case of one boiler, which showed an increase going from BA to ESPA. Only Br decreased in composition going from BA to ESPA. Rb, Sm, U, and Th showed marked variation in trends. The major elements identified by EDS were Al, Si, S, K, Ca, Fe, and Ba, with minor amounts of Mg, Na, Ti, Mn, and Sr. Al, Si, K, and Ca occur together and are present in most of the fly-ash particles. Ba was found as a major component with Ca, Al, and Si. Fe and Ca are usually associated with sulfur. Some small spheres (< 5 {mu}m) are comprised almost entirely of Fe (probably as oxide). Symplectite textures are noted in high-Fe phases. All elements except Br are significantly enriched in the fly ash relative to the coal, which contains 35% ash. Particle chemistry is consistent with the major mineral phases identified by XRD, which include: quartz, magnetite, mullite, gehlenite, anorthite, hematite, anhydrite, and clinopyroxene.« less

The Easternmost Southwest Indian Ridge: A Laboratory to Study MORB and Oceanic Gabbro Petrogenesis in a Very Low Melt Supply Context

NASA Astrophysics Data System (ADS)

Paquet, M.; Cannat, M.; Hamelin, C.; Brunelli, D.

2014-12-01

Our study area is located at the ultra-slow Southwest Indian Ridge, east of the Melville Fracture Zone, between 61 and 67°E. The melt distribution in this area is very heterogeneous, with corridors of ultramafic seafloor where plate separation is accommodated by large offset normal faults [Sauter, Cannat et al., 2013]. These ultramafic corridors also expose rare gabbros and basalts. We use the major and trace elements composition of these magmatic rocks to document the petrogenesis of MORB in this exceptionnally low melt supply portion of the MOR system. Basalts from the easternmost SWIR represent a global MORB end-member for major element compositions [Meyzen et al., 2003], with higher Na2O and Al2O3 wt%, and lower CaO and FeO wt% at a given MgO. Within this group, basalts from the ultramafic corridors have particularly high Na2O, low CaO and FeO wt%. Best fitting calculated liquid lines of descent are obtained for crystallization pressures of ~8 kbar. Gabbroic rocks recovered in the ultramafic corridors include gabbros, oxide-gabbros and variably impregnated peridotites. This presentation focuses on these impregnated samples, where cpx have high Mg#, yet are in equilibrium with the nearby basalts in terms of their trace element compositions. Plagioclase An contents vary over a broad range, and there is evidence for opx resorption. These characteristics result from melt-mantle interactions in the axial lithosphere, which may explain several peculiar major element characteristics of the basalts. Similar interactions probably occur beneath ridges at intermediate to slow and ultraslow spreading rates. We propose that they are particularly significant in our study area due to its exceptionnally low integrated melt-rock ratio.

Electronic structure, phase transitions and diffusive properties of elemental plutonium

NASA Astrophysics Data System (ADS)

Setty, Arun; Cooper, B. R.

2003-03-01

We present a SIC-LDA-LMTO based study of the electronic structure of the delta, alpha and gamma phases of plutonium, and also of the alpha and gamma phases of elemental cerium. We find excellent agreement with the experimental densities and magnetic properties [1]. Furthermore, detailed studies of the computational densities of states for delta plutonium, and comparison with the experimental photoemission spectrum [2], provide evidence for the existence of an unusual fluctuating valence state. Results regarding the vacancy formation and self-diffusion in delta plutonium will be presented. Furthermore, a study of interface diffusion between plutonium and steel (technologically relevant in the storage of spent fuel) or other technologically relevant alloys will be included. Preliminary results regarding gallium stabilization of delta plutonium, and of plutonium alloys will be presented. [1] M. Dormeval et al., private communication (2001). [2] A. J. Arko, J. J. Joyce, L. Morales, J. Wills, and J. Lashley et. al., Phys. Rev. B, 62, 1773 (2000). [3] B. R. Cooper et al, Phil. Mag. B 79, 683 (1999); B.R. Cooper, Los Alamos Science 26, 106 (2000)); B.R. Cooper, A.K. Setty and D.L.Price, to be published.

Concepts for the Next Generation Space Telescope

NASA Astrophysics Data System (ADS)

Margulis, M.; Tenerelli, D.

1996-12-01

In collaboration with NASA GSFC, we have examined a wide range of potential concepts for a large, passively cooled space telescope. Our design goals were to achieve a theoretical imaging sensitivity in the near-IR of 1 nJy and an angular resolution at 1 micron of 0.06 arcsec. Concepts examined included a telescope/spacecraft system with a 6-m diameter monolithic primary mirror, a variety of telescope/spacecraft systems with deployable primary mirror segments to achieve an 8-m diameter aperture, and a 12-element sparse aperture phased array telescope. Trade studies indicate that all three concept categories can achieve the required sensitivity and resolution, but that considerable technology development is required to bring any of the concepts to fruition. One attractive option is the system with the 6-m diameter monolithic primary. This option achieves high sensitivity without telescope deployments and includes a stiff structure for robust attitude and figure control. This system capitalizes on coming advances in launch vehicle and shroud technology, which should enable launch of large, monolithic payloads into orbit positions where background noise due to zodiacal dust is low. Our large space telescope study was performed by a consortium of organizations and individuals including: Domenick Tenerelli et al. (Lockheed Martin Corp.), Roger Angel et al. (U. Ariz.), Tom Casey et al. (Eastman Kodak Co.), Jim Gunn (Princeton), Shel Kulick (Composite Optics, Inc.), Jim Westphal (CIT), Johnny Batache et al. (Harris Corp.), Costas Cassapakis et al. (L'Garde, Inc.), Dave Sandler et al. (ThermoTrex Corp.), David Miller et al. (MIT), Ephrahim Garcia et al. (Garman Systems Inc.), Mark Enright (New Focus Inc.), Chris Burrows (STScI), Roc Cutri (IPAC), and Art Bradley (Allied Signal Aerospace).

Heavy Element Abundances in Two B0-B0.5 Main Sequence Stars in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Peters, Geraldine J.

We propose FUSE observations of AV304 (B0.5V) and NGC346-637 B0V), two sharp-lined main-sequence stars in the Small Magellanic Cloud, to determine the abundances of heavy elements, especially those of the iron group. The FUSE spectral region contains numerous Fe III lines, including the resonance multiplet (UV 1) near 1130 Angstroms, that is excellent for abundance determinations and two strong multiplets of V III, an ion that does not produce measurable lines longward of 1200 Angstoms, in metal-deficient stars. In addition there are several measurable lines from Cr III and Mn III. A limited analyses of ground-based spectra of these stars by Dufton et al. (1990) and Rolleston et al. (1993) indicated an average underabundance of 0.7-0.8 dex for most light elements and a recent analysis of HSTSTIS data on AV304 by Peters & Grigsby (2001) suggests that the Fe group elements are depleted by the same amount relative to the sun. When combined with the HST-STIS results, this effort will represent the first attempt to measure the abundances of Fe group elements in the photospheres of early B, main sequence stars in an external galaxy. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, the ground-based study did not yield this information because measurable lines from these species are found only in the UV spectral region. Abundances and abundance ratios of both heavy & light elements will be compared with the HST-STIS results from AV304, H II regions, supernova remnants, evolved massive stars in the SMC, and theoretical calculations of nucleosynthesis.

Hypervelocity Impact Behaviour of CFRP-A1/HC Sandwich Panel: Finite-Element Studies

NASA Astrophysics Data System (ADS)

Phadnis, Vaibhav A.; Roy, Anish; Silberschmidt, Vadim V.

2014-06-01

The mechanical response of CFRP-Al/HC (carbon fibre- reinforced/epoxy composite face sheets with Al honeycomb core) sandwich panels to hyper-velocity impact ( 1 km/s) is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by the means of a user-defined material model (VUMAT) employing a combination of Hashin and Puck criteria and delamination is modelled using cohesive-zone elements. The damage of Al/HC core is assessed on the basis of a Johnson-Cook dynamic failure model while its hydrodynamic response is captured using the Mie- Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing of HC core.

Reactive codoping of GaAlInP compound semiconductors

DOEpatents

Hanna, Mark Cooper [Boulder, CO; Reedy, Robert [Golden, CO

2008-02-12

A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

Magnetic and noncentrosymmetric Weyl fermion semimetals in the R AlGe family of compounds (R =rare earth )

NASA Astrophysics Data System (ADS)

Chang, Guoqing; Singh, Bahadur; Xu, Su-Yang; Bian, Guang; Huang, Shin-Ming; Hsu, Chuang-Han; Belopolski, Ilya; Alidoust, Nasser; Sanchez, Daniel S.; Zheng, Hao; Lu, Hong; Zhang, Xiao; Bian, Yi; Chang, Tay-Rong; Jeng, Horng-Tay; Bansil, Arun; Hsu, Han; Jia, Shuang; Neupert, Titus; Lin, Hsin; Hasan, M. Zahid

2018-01-01

Weyl semimetals are novel topological conductors that host Weyl fermions as emergent quasiparticles. In this Rapid Communication, we propose a new type of Weyl semimetal state that breaks both time-reversal symmetry and inversion symmetry in the R AlGe (R =rare -earth ) family. Compared to previous predictions of magnetic Weyl semimetal candidates, the prediction of Weyl nodes in R AlGe is more robust and less dependent on the details of the magnetism because the Weyl nodes are generated already by the inversion breaking and the ferromagnetism acts as a simple Zeeman coupling that shifts the Weyl nodes in k space. Moreover, R AlGe offers remarkable tunability, which covers all varieties of Weyl semimetals including type I, type II, inversion breaking, and time-reversal breaking, depending on a suitable choice of the rare-earth elements. Furthermore, the unique noncentrosymmetric and ferromagnetic Weyl semimetal state in R AlGe enables the generation of spin currents.

Precision Half-life Measurement of 25Al

NASA Astrophysics Data System (ADS)

Long, Jacob; Ahn, Tan; Allen, Jacob; Bardayan, Daniel; Becchetti, Fredrich; Blankstein, Drew; Brodeur, Maxime; Burdette, Daniel; Frentz, Bryce; Hall, Matthew; Kelly, James; Kolata, James; O'Malley, Patrick; Schultz, Bradley; Strauss, Sabrina; Valverde, Adrian; TwinSol Collaboration

2017-09-01

In recent years, precision measurements have led to considerable advances in several areas of physics, including fundamental symmetry. Precise determination of ft values for superallowed mixed transitions between mirror nuclides could provide an avenue to test the theoretical corrections used to extract the Vud matrix element from superallowed pure Fermi transitions. Calculation of the ft value requires the half-life, branching ratio, and Q value. 25Al decay is of particular interest as its half-life is derived from a series of conflicting measurements, and the largest uncertainty on the ft value stems from the half-life uncertainty. The life-time was determined by the β counting of implanted 25Al on a Ta foil that was removed from the beam for counting. The 25Al beam was produced by a transfer reaction and separated by the TwinSol facility of the Nuclear Science Laboratory of the University of Notre Dame. The 25Al results will be presented with preliminary results of more recent half-life measurements. The National Science Foundation.

Particle size effects on bioaccessible amounts of ingestible soil-borne toxic elements.

PubMed

Qin, Junhao; Nworie, Obinna Elijah; Lin, Chuxia

2016-09-01

The unified BARGE method was used to examine the effects of soil particle size on the bioaccessible amounts of potentially toxic elements in multi-contaminated soils from a closed landfill site. The results show that bioaccessible As, Al, Cd, Cr, Cu, Mn, Ni, Pb and Zn increased with decreasing soil particle size and the <0.002 mm soil fraction contained much greater amounts of the bioaccessible elements, as compared to other soil fractions (0.002-0.063 mm, 0.063-0.125 mm, and 0.125-0.250 mm). As, Al and Cr had much lower bioaccessibility, as compared to the six cationic heavy metals. In contrast with other elements, As bioaccessibility tended to be higher in the gastrointestinal phase than in the gastric phase. There was a significant soil particle size effect on bioaccessibility of As and Al in the gastrointestinal phase: As bioaccessibility decreased with decreasing particle size, and the finer soil fractions tended to have a higher Al bioaccessibility, as compared to the coarser soil fractions. The research findings prompt the need for further division of soil particle size fractions in order to more accurately assess the bioaccessible amounts of soil-borne potentially toxic elements in contaminated lands. Copyright © 2016 Elsevier Ltd. All rights reserved.

Aluminum-induced entropy in biological systems: implications for neurological disease.

PubMed

Shaw, Christopher A; Seneff, Stephanie; Kette, Stephen D; Tomljenovic, Lucija; Oller, John W; Davidson, Robert M

2014-01-01

Over the last 200 years, mining, smelting, and refining of aluminum (Al) in various forms have increasingly exposed living species to this naturally abundant metal. Because of its prevalence in the earth's crust, prior to its recent uses it was regarded as inert and therefore harmless. However, Al is invariably toxic to living systems and has no known beneficial role in any biological systems. Humans are increasingly exposed to Al from food, water, medicinals, vaccines, and cosmetics, as well as from industrial occupational exposure. Al disrupts biological self-ordering, energy transduction, and signaling systems, thus increasing biosemiotic entropy. Beginning with the biophysics of water, disruption progresses through the macromolecules that are crucial to living processes (DNAs, RNAs, proteoglycans, and proteins). It injures cells, circuits, and subsystems and can cause catastrophic failures ending in death. Al forms toxic complexes with other elements, such as fluorine, and interacts negatively with mercury, lead, and glyphosate. Al negatively impacts the central nervous system in all species that have been studied, including humans. Because of the global impacts of Al on water dynamics and biosemiotic systems, CNS disorders in humans are sensitive indicators of the Al toxicants to which we are being exposed.

Aluminum-Induced Entropy in Biological Systems: Implications for Neurological Disease

PubMed Central

Shaw, Christopher A.; Seneff, Stephanie; Kette, Stephen D.; Tomljenovic, Lucija; Oller, John W.; Davidson, Robert M.

2014-01-01

Over the last 200 years, mining, smelting, and refining of aluminum (Al) in various forms have increasingly exposed living species to this naturally abundant metal. Because of its prevalence in the earth's crust, prior to its recent uses it was regarded as inert and therefore harmless. However, Al is invariably toxic to living systems and has no known beneficial role in any biological systems. Humans are increasingly exposed to Al from food, water, medicinals, vaccines, and cosmetics, as well as from industrial occupational exposure. Al disrupts biological self-ordering, energy transduction, and signaling systems, thus increasing biosemiotic entropy. Beginning with the biophysics of water, disruption progresses through the macromolecules that are crucial to living processes (DNAs, RNAs, proteoglycans, and proteins). It injures cells, circuits, and subsystems and can cause catastrophic failures ending in death. Al forms toxic complexes with other elements, such as fluorine, and interacts negatively with mercury, lead, and glyphosate. Al negatively impacts the central nervous system in all species that have been studied, including humans. Because of the global impacts of Al on water dynamics and biosemiotic systems, CNS disorders in humans are sensitive indicators of the Al toxicants to which we are being exposed. PMID:25349607

Source and fate of inorganic solutes in the Gibbon River, Yellowstone National Park, Wyoming, USA. II. Trace element chemistry

USGS Publications Warehouse

McCleskey, R. Blaine; Nordstrom, D. Kirk; Susong, David D.; Ball, James W.; Taylor, Howard E.

2010-01-01

The Gibbon River in Yellowstone National Park receives inflows from several geothermal areas, and consequently the concentrations of many trace elements are elevated compared to rivers in non-geothermal watersheds. Water samples and discharge measurements were obtained from the Gibbon River and its major tributaries near Norris Geyser Basin under the low-flow conditions of September 2006 allowing for the identification of solute sources and their downstream fate. Norris Geyser Basin, and in particular Tantalus Creek, is the largest source of many trace elements (Al, As, B, Ba, Br, Cs, Hg, Li, Sb, Tl, W, and REEs) to the Gibbon River. The Chocolate Pots area is a major source of Fe and Mn, and the lower Gibbon River near Terrace Spring is the major source of Be and Mo. Some of the elevated trace elements are aquatic health concerns (As, Sb, and Hg) and knowing their fate is important. Most solutes in the Gibbon River, including As and Sb, behave conservatively or are minimally attenuated over 29 km of fluvial transport. Some small attenuation of Al, Fe, Hg, and REEs occurs but primarily there is a transformation from the dissolved state to suspended particles, with most of these elements still being transported to the Madison River. Dissolved Hg and REEs loads decrease where the particulate Fe increases, suggesting sorption onto suspended particulate material. Attenuation from the water column is substantial for Mn, with little formation of Mn as suspended particulates.

New trace element determinations in the fingernails of ALS patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Dalsem, D.J.; Ehmann, W.D.; Robinson, L.

1996-12-31

Amyotrophic lateral sclerosis (ALS) afflicts 2 of every 100,000 people in the United States each year. A well-known example of ALS today is Stephen Hawking. He is a theoretical physicist, the author of A Brief History of Time, and is virtually immobilized by ALS. Diseases that cause progressive paralysis because of motor neuron degeneration in the central nervous system are termed motor neuron disorders (MND). Amyotrophic lateral sclerosis is a common form of MND. Pain-free, progressive muscular weakness is the most common clinical symptom. There is chronic weakness with atrophy of the affected muscles by the time the disease ismore » diagnosed. Atrophy eventually results in wheelchair confinement and then only bed without the ability to speak or swallow. Death often occurs as a result of respiratory problems. Unlike other neurodegenerative diseases, in ALS the patient`s bladder and bowel control, eye movement, and mental faculties are preserved. The question today is whether or not certain trace elements are involved in the etiology or pathogenesis of ALS. A collaborative study was undertaken by the University of Kentucky and Oak Ridge National Laboratory (ORNL) using neutron activation analysis (NAA) to study trace element concentrations in ALS patients fingernails to determine if there existed statistically significant imbalances.« less

Trace Elements in Calcifying Marine Invertebrates Indicate Diverse Sensitivities to the Seawater Carbonate System

NASA Astrophysics Data System (ADS)

Doss, W. C.

2015-12-01

Surface ocean absorption of anthropogenic CO2 emissions resulting in ocean acidification may interfere with the ability of calcifying marine organisms to biomineralize, since the drop in pH is accompanied by reductions in CaCO3 saturation state. However, recent experiments show that net calcification rates of cultured benthic invertebrate taxa exhibit diverse responses to pCO2-induced changes in saturation state (Ries et al., 2009). Advancement of geochemical tools as biomineralization indicators will enable us to better understand these results and therefore help predict the impacts of ongoing and future decrease in seawater pH on marine organisms. Here we build upon previous work on these specimens by measuring the elemental composition of biogenic calcite and aragonite precipitated in four pCO2 treatments (400; 600; 900; and 2850 ppm). Element ratios (including Sr/Ca, Mg/Ca, Li/Ca, B/Ca, U/Ca, Ba/Ca, Cd/Ca, and Zn/Ca) were analyzed in 18 macro-invertebrate species representing seven phyla (crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida), then compared to growth rate data and experimental seawater carbonate system parameters: [CO32-], [HCO3-], pH, saturation state, and DIC. Correlations between calcite or aragonite composition and seawater carbonate chemistry are highly taxa-specific, but do not resemble trends observed in growth rate for all species. Apparent carbonate system sensitivities vary widely by element, ranging from strongly correlated to no significant response. Interpretation of these results is guided by mounting evidence for the capacity of individual species to modulate pH and/or saturation state at the site of calcification in response to ambient seawater chemistry. Such biomineralization pathways and strategies in turn likely influence elemental fractionation during CaCO3 precipitation. Ries, J.B., A.L. Cohen, A.L., and D.C. McCorkle (2009), Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification, Geology, 37(12), 1131-1134.

Uptake of Elements From Aerosols by Humans ~ A Case Study From Delhi & Bangalore Cities

NASA Astrophysics Data System (ADS)

Anand, S.; Yadav, S.; Jain, V. K.

2006-05-01

Aerosol research has gained tremendous importance globally due to the cumulative effects of increasing industrialization and urbanization on aerosol production which can have an alarming impact on the climate of the planet as well as the health of its inhabitants. Therefore, there is an increasing need to study aerosols for all of their physicochemical and biological aspects on both local and global scales. World over extensive research has gone into studying the physical and the chemical aspects of aerosols. However, little information is yet available on the health impacts of aerosols particularly in the Asian context. Here we report uptake of various elements that are concentrated in aerosols by the human body in Delhi and Bangalore cities and their possible health effects. In many urban areas, for example in Delhi, inhalable fractions of aerosols are known to have high concentrations of elements such as Cu, Zn, Pb, Ba, Ni and Cr (Yadav and Rajamani 2004). Also aerosols in the North West part of India seem to be particularly enriched in these elements. If so, there is a high possibility of these elements getting into the human system either directly or indirectly through water and food. To determine the concentrations of these elements that are present in significant concentrations in the inhalable fractions of aerosols, human hair and blood samples are used as proxies. Both these regions have contrasting geographic and climatic conditions. Delhi (altitude : 213-305m above MSL) located on the fringes of the Thar desert which supplies considerable amount of dust, is semi-arid with annual rainfall of 60-80 cms & temperatures varying between 1° - 45°. Bangalore (altitude of 900m above MSL) receives a high annual rainfall of 80-100 cms and being located on the fringes of tropical forests of the Sahyadri Mountains (Western Ghats) receives little crustal contribution to the aerosols. Samples from least polluted mountainous areas of Himalayas (Gangothri) and Sahyadri (Ooty) were also collected as reference samples. All the samples were digested in a microwave system. Elemental analyses were carried out using both ICP-MS and ICP-AES methods using multi-element standard solutions from Merck. The elements analyzed include Al, Ca, Mg, Ni, Cu, Ba, Zn, Pb, Cr, Sr, K, Na, Si, and P in about 100 samples of blood and hair. Preliminary results indicate a possible human uptake of elements from the aerosols. In comparison to the international reference and local background values (Gangothri), Delhi and Bangalore samples of human hair and blood show significant enrichment of these elements. Samples from Gangothri are comparable to those of the international reference values. Delhi samples have much higher concentrations of several elements, especially Al, Zn, Pb and Cu. Although the Bangalore samples are also enriched compared to the reference values, they are much less enriched relative to the Delhi samples. Bangalore samples have negligible contributions from the crustal aerosols as compared to the Delhi samples where the crustal contributions seem to be very high. Elements enriched in the PM 10 aerosols or the respirable fractions include Ca, Mg, Al (crustal) and Ba, Zn,Cu, Pb, Ni, Cr (anthropogenic). In all the samples, hair seems to be a better long term indicator of elemental uptake compared to blood. The health effect of aerosols can be several as indicated by studies elsewhere and will be discussed.

Metallic elements occurrences within metallic fragments in the municipal waste incineration bottom ash

NASA Astrophysics Data System (ADS)

Kowalski, Piotr; Kasina, Monika; Michalik, Marek

2017-04-01

Bottom ash (BA) from municipal solid waste incineration (MSWI) is composed of grainy ash material, residual components and metallic fragments (from few µm up to 3-5 cm). Its mineral and chemical composition is related to the composition of the waste stream in the incinerator operational area. Wide use of thermal techniques in management of solid waste makes important the studies on valuable components and their distribution within the material in terms of their further processing. By using various valorization or extraction techniques it is possible to extend the range of its possible further application. To investigate metallic elements distribution within metallic fragments of the MSWI BA material produced in municipal waste incineration plant in Poland were collected in 2015 and 2016. BA and its components were investigated using spectroscopic methods of chemical analysis: ICP-OES, ICP-MS, LECO and EDS (used for microanalysis during SEM observations). BA is a material rich in Si (22.5 wt%), Ca (13.4 wt%), Fe (4 wt%), Al (5.2 wt%) and Na (3.5 wt%), composed of equal part of amorphous (silicate glass dominated) and crystalline phase (rich in silicates, aluminosilicates, oxides of non- and metallic elements and sulphates). The content of metallic elements (Al, Fe, Mg, Ti, Mn, Cr, Ni, Sc, Mo, Cu, Pb, Zn, Sn) is 11.5 wt% with domination of Al (5.2 wt%) and Fe (4 wt%) and elevated values of Mg (1 wt%), Ti (0.54 wt%), Cu (0.26 wt%) and Zn (0.27 wt%) (Kowalski et al., 2016). They were mostly concentrated in the form of metallic fragments, mainly as metallic inclusions in the size of 1-20 µm and separated metallic grains in the size of 50-300 µm. Metallic fragments present in the BA are characterized by their composition heterogeneity and various oxygen content. Fragments are rarely composed of single metallic element and usually in their composition up to few main elements dominated over others. The most common were Fe-, Al- and Zn-rich fragments forming respectively 70%, 15% and 5% of the total amount of fragments. Fe occurred mainly as component of metallic inclusions and separate grains. Al was mostly present in metallic fragments on grains boundaries and also and as separate grains (often oxidised), moreover Al was important component of aluminosilicates and amorphous phase. Zn-rich metallic fragments were mostly in the form of separate grains. In complex composition of metallic fragments some regularities in elements co-occurrences were observed: Fe often co-existed with Si, Ca, P, Al and Ti; Al co-occurred with Fe, Si and Ca; Zn co-existed with Ca, Al and Si. Forms and composition of metallic fragments allows to evaluate them as potential polymetallic resource, however an economically reasonable extraction techniques must be applied. Acknowledgment Research was funded by Polish National Science Centre (NCN). Scientific grant No. UMO-2014/15/B/ST10/04171. Reference Kowalski, P.R., Kasina, M. and Michalik M.: Metallic elements fractionation in municipal solid waste incineration residues, Energy Procedia, 97, 31-36, doi: 10.1016/j.egypro.2016.10.013, 2016.

Behaviour of aluminium in forest soils with different lithology and herb vegetation cover.

PubMed

Hubová, Petra; Tejnecký, Václav; Češková, Michaela; Borůvka, Luboš; Němeček, Karel; Drábek, Ondřej

2018-04-01

The aim of this study was to determine the content, distribution and behaviour of Al in soils under beech forest with different parent rock, and to assess the role of herbaceous vegetation on soil Al behaviour. We hypothesize that the contents of elements in the soil sorption complex (Al etc.) are strongly influenced by vegetation cover. Also, low molecular mass organic acids (LMMOA) can be considered as an indicator of soil organic matter (SOM) decomposition and vegetation litter turnover. Speciation of LMMOA, nutrition content (PO 4 3- , Ca 2+ , K + ) and element composition in aqueous extracts were determined by means of ion chromatography and inductively coupled plasma - optical emission spectrometry (ICP-OES) respectively. Active and exchangeable pH, sorption characteristics and exchangeable Al (Al ex ) were determined in BaCl 2 extracts by ICP-OES. Elemental composition of parent rocks was assessed by means of X-ray fluorescence spectroscopy. Herb-poor localities showed lower pH, less nutrients (PO 4 3- , Ca 2+ , K + ), less LMMOA, a larger stock of SOM and greater cation exchange capacity. There was also lower mobilisation of Al in organic horizons, which explains the larger pools of Al. Generally, we can conclude that LMMOA, and thus soil vegetation cover, play an important role in the Al soil cycle. Copyright © 2017 Elsevier Inc. All rights reserved.

Hydrothermal Synthesis and Characterization of Ni-Al Montmorillonite-Like Phyllosilicates

PubMed Central

Reinholdt, Marc X.; Brendlé, Jocelyne; Tuilier, Marie-Hélène; Kaliaguine, Serge; Ambroise, Emmanuelle

2013-01-01

This work describes the first hydrothermal synthesis in fluoride medium of Ni-Al montmorillonite-like phyllosilicates, in which the only metallic elements in the octahedral sheet are Ni and Al. X-ray diffraction , chemical analysis, thermogravimetric and differential thermal analysis, scanning electron microscopy and transmission electron microscopy confirm that the synthesized samples are montmorillonite-like phyllosilicates having the expected chemical composition. The specific surface areas of the samples are relatively large (>100 m2 g−1) compared to naturally occurring montmorillonites. 29Si and 27Al nuclear magnetic resonance (NMR) indicate substitutions of Al for Si in the tetrahedral sheet. 19F NMR and Ni K-edge extended X-ray absorption fine structure (EXAFS) local probes highlight a clustering of the metal elements and of the vacancies in the octahedral sheet of the samples. These Ni-Al phyllosilicates exhibit a higher local order than in previously synthesized Zn-Al phyllosilicates. Unlike natural montmorillonites, where the distribution of transition metal cations ensures a charge equilibrium allowing a stability of the framework, synthetic montmorillonites entail clustering and instability of the lattice when the content of divalent element in the octahedral sheet exceeds ca. 20%. Synthesis of Ni-Al montmorillonite-like phyllosilicates, was successfully achieved for the first time. These new synthetic materials may find potential applications as catalysts or as materials with magnetic, optical or staining properties. PMID:28348321

Baseline element concentrations in soils and plants, Bull Island, Cape Romain National Wildlife Refuge, South Carolina, U.S.A.

USGS Publications Warehouse

Gough, L.P.; Severson, R.C.; Jackson, L.L.

1994-01-01

Baseline element concentrations are given for Spanish moss (Tillandsia usneoides), loblolly pine (Pinus taeda), and associated soils. Baseline and variability data for ash, Al, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Sr, Th, Ti, V, Y, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration among and within 0.5 km grid cells are given for each of the media. In general, only a few elements in Spanish moss showed statistically significant landscape patterns, whereas several elements in loblolly pine and in soils exhibited differences among sampling grids. Significant differences in the concentration of three elements in Spanish moss and eight elements (including total S) in loblolly pine were observed between two sampling dates (November and June); however, the absolute amount of these differences was small. Except for perhaps Ni and Pb concentrations in Spanish moss, element levels in all sample media exhibited ranges that indicate natural rather than anthropogenic additions of trace elements.

Aluminium exposure disrupts elemental homeostasis in Caenorhabditis elegans†

PubMed Central

Page, Kathryn E.; White, Keith N.; McCrohan, Catherine R.

2013-01-01

Aluminium (Al) is highly abundant in the environment and can elicit a variety of toxic responses in biological systems. Here we characterize the effects of Al on Caenorhabditis elegans by identifying phenotypic abnormalities and disruption in whole-body metal homeostasis (metallostasis) following Al exposure in food. Widespread changes to the elemental content of adult nematodes were observed when chronically exposed to Al from the first larval stage (L1). Specifically, we saw increased barium, chromium, copper and iron content, and a reduction in calcium levels. Lifespan was decreased in worms exposed to low levels of Al, but unexpectedly increased when the Al concentration reached higher levels (4.8 mM). This bi-phasic phenotype was only observed when Al exposure occurred during development, as lifespan was unaffected by Al exposure during adulthood. Lower levels of Al slowed C. elegans developmental progression, and reduced hermaphrodite self-fertility and adult body size. Significant developmental delay was observed even when Al exposure was restricted to embryogenesis. Similar changes in Al have been noted in association with Al toxicity in humans and other mammals, suggesting that C. elegans may be of use as a model for understanding the mechanisms of Al toxicity in mammalian systems. PMID:22534883

Spatial analysis of Puerto Rico's terrestrial protected areas [1:240 000

Treesearch

M. Quinones; W.A. Gould; J. Castro-Prieto; S. Martinuzzi

2013-01-01

This research map describes Puerto Rico's terrestrial protected areas based on natural and anthropogenic elements of the landscape. We used geospatial data, i.e., land cover (Gould et al. 2007); urban, suburban, and rural settlements (Martinuzzi et al. 2008); and physiography to illustrate landscape elements and analyze what and how much is protected in Puerto...

Phytoextraction of potentially toxic elements by Indian mustard, rapeseed, and sunflower from a contaminated riparian soil.

PubMed

Shaheen, Sabry M; Rinklebe, Jörg

2015-12-01

The objective of this study was to quantify the phytoextraction of the potentially toxic elements Al, As, Cd, Co, Cr, Cu, Mo, Ni, Pb, Se, V, and Zn by Indian mustard, rapeseed, and sunflower from a contaminated riparian soil. To achieve this goal, a greenhouse pot experiment was established using a highly contaminated grassland soil collected at the Wupper River (Germany). The impact of ethylene-diamine-tetra-acetic acid (EDTA), humate (HK), and phosphate potassium (PK) on the mobility and uptake of the elements by rapeseed also was investigated. Indian mustard showed the highest efficiency for phytoextraction of Al, Cr, Mo, Se, and V; sunflower for Cd, Ni, Pb, and Zn, and rapeseed for Cu. The bioconcentration ratios were higher than 1 for the elements (except As and Cu), indicating the suitability of the studied plants for phytoextraction. Application of EDTA to the soil increased significantly the solubility of Cd, Co, Cr, Ni, and Pb and decreased the solubility of Al, As, Se, V, and Mo. Humate potassium decreased significantly the concentrations of Al and As in rapeseed but increased the concentrations of Cu, Se, and Zn. We may conclude that HK can be used for immobilization of Al and As, while it can be used for enhancing the phytoextraction of Cu, Se, and Zn by rapeseed. Phosphate potassium immobilized Al, Cd, Pb, and Zn, but enhanced phytoextraction of As, Cr, Mo, and Se by rapeseed.

NanoSIMS opens a New Window for Deciphering Organic Matter in Terrestrial and Extraterrestrial Samples

NASA Technical Reports Server (NTRS)

Oehler, Dorothy ZS.; Robert, Francois; Mostefaoui, Smail; Meibom, Anders; Selo, Madeleine; McKay, David S.; Gibson, Everett K.

2007-01-01

Recognition of the earliest morphological or chemical evidence of terrestrial life has proved to be challenging, as organic matter in ancient rocks is commonly fragmentary and difficult to distinguish from abiotically-produced materials (Schopf, 1993; Van Zuilen et al., 2002; Altermann & Kazmierczak, 2003; Cady et al., 2003; Brasier et al., 2002, 2004, 2005; Hofmann, 2004; Skrzypczak et al., 2004, 2005). Yet, the ability to identify remnants of earliest life is critical to our understanding of the timing of life's origin on earth, the nature of earliest terrestrial life, and recognition of potential remnants of microbial life that might occur in extraterrestrial materials. The search for earliest life on Earth now extends to early Archean organic remains; these tend to be very poorly preserved and considerably more difficult to interpret than the delicately permineralized microfossils known from many Proterozoic deposits. Thus, recent efforts have been directed toward finding biosignatures that can help distinguish fragmentary remnants of ancient microbes from either pseudofossils or abiotic organic materials that may have formed hydrothermally or in extraterrestrial processes (House et al., 2000; Boyce et al., 2001; Kudryavtsev et al., 2001; Schopf, 2002; Schopf et al., 2002, 2005a,b; Cady et al., 2003; Garc a-Ruiz et al., 2003; Hofmann, 2004; Brasier et al., 2005; Rushdi and Simoneit, 2005; Skrzypczak et al., 2005). An exciting area of biosignature research involves the developing technology of NanoSIMS. NanoSIMS is secondary ion mass spectrometry (SIMS) for ultrafine feature, elemental and isotopic analysis. Its resolution approaches 0.05 micrometers for element mapping, which is 10-50 times finer than that attainable with conventional SIMS or electron microprobes. Consequently, NanoSIMS has the potential to reveal previously unknown, chemical and structural characteristics of organic matter preserved in geologic materials. Robert et al. (2005) were the first to combine NanoSIMS element maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity. They showed that the ability to simultaneously map the distribution of organic elements [such as carbon (C), nitrogen (N), and sulfur (S)] and compare those element distributions with optically recognizable, cellularly preserved fossils could provide significant new insights into the origin of organic materials in ancient sediments. This chapter details a recent NanoSIMS study which was designed to acquire new data relevant to establishing critical biosignatures (Oehler et al., 2006a-c). In this study, NanoSIMS was used to characterize element distributions of spheroidal and filamentous microfossils and associated organic laminae in chert from the approx. 0.85 billion year old (Ga) Bitter Springs Formation of Australia. Previous work established preservation of a diverse microbiota in the Bitter Springs Formation (Schopf, 1968; Schopf and Blacic, 1971), and there is no dispute within the scientific community regarding the biogenicity of any of the Bitter Springs structures evaluated in this new study. Thus, the NanoSIMS results described below provide new insight into - and can be used as a guide for assessing - the origin of less well understood organic materials that may occur in early Archean samples and in meteorites or other extraterrestrial samples.

Using Formal Game Design Methods to Embed Learning Outcomes into Game Mechanics and Avoid Emergent Behaviour

ERIC Educational Resources Information Center

Grey, Simon; Grey, David; Gordon, Neil; Purdy, Jon

2017-01-01

This paper offers an approach to designing game-based learning experiences inspired by the Mechanics-Dynamics-Aesthetics (MDA) model (Hunicke et al., 2004) and the elemental tetrad model (Schell, 2008) for game design. A case for game based learning as an active and social learning experience is presented including arguments from both teachers and…

Psychological Operations: Fighting the War of Ideas

DTIC Science & Technology

2007-05-18

is the success of the Joint Interagency Task Force on the Former Regime Elements (JIATF- FRE) operation to capture Fadhil Ibrahim Habib al-Mashadani... DAPS ), Fly Away Broadcast System (FABS), and Target Audience Analysis Detachment (TAAD). This provides the Brigade a radio development and broadcast...level. Production and dissemination assets must include a Modular Print System (MPS), Deployable Audio Production Suite ( DAPS ), and Special

A Viable Scheme for Elemental Extraction and Purification Using In-Situ Planetary Resources

NASA Technical Reports Server (NTRS)

Sen, S.; Schofield, E.; ODell, S.; Ray, C. S.

2005-01-01

NASA's new strategic direction includes establishing a self-sufficient, affordable and safe human and robotic presence outside the low earth orbit. Some of the items required for a self-sufficient extra-terrestrial habitat will include materials for power generation (e.g. Si for solar cells) and habitat construction (e.g. Al, Fe, and Ti). In this paper we will present a viable elemental extraction and refining process from in-situ regolith which would be optimally continuous, robotically automated, and require a minimum amount of astronaut supervision and containment facilities, The approach is based on using a concentrated heat source and translating sample geometry to enable simultaneous oxide reduction and elemental refining. Preliminary results will be presented to demonstrate that the proposed zone refining process is capable of segregating or refining important elements such as Si (for solar cell fabrication) and Fe (for habitat construction). A conceptual scheme will be presented whereby such a process could be supported by use of solar energy and a precursor robotic mission on the surface of the moon.

Architecture and Functionality of the Advanced Life Support On-Line Project Information System

NASA Technical Reports Server (NTRS)

Hogan, John A.; Levri, Julie A.; Morrow, Rich; Cavazzoni, Jim; Rodriguez, Luis F.; Riano, Rebecca; Whitaker, Dawn R.

2004-01-01

An ongoing effort is underway at NASA Ames Research Center (ARC) to develop an On-line Project Information System (OPIS) for the Advanced Life Support (ALS) Program. The objective of this three-year project is to develop, test, revise and deploy OPIS to enhance the quality of decision-making metrics and attainment of Program goals through improved knowledge sharing. OPIS will centrally locate detailed project information solicited from investigators on an annual basis and make it readily accessible by the ALS Community via a Web-accessible interface. The data will be stored in an object-oriented relational database (created in MySQL) located on a secure server at NASA ARC. OPE will simultaneously serve several functions, including being an research and technology development (R&TD) status information hub that can potentially serve as the primary annual reporting mechanism for ALS-funded projects. Using OPIS, ALS managers and element leads will be able to carry out informed R&TD investment decisions, and allow analysts to perform accurate systems evaluations. Additionally, the range and specificity of information solicited will serve to educate technology developers of programmatic needs. OPIS will collect comprehensive information from all ALS projects as well as highly detailed information specific to technology development in each ALS area (Waste, Water, Air, Biomass, Food, Thermal, Controls and Systems Analysis). Because the scope of needed information can vary dramatically between areas, element-specific technology information is being compiled with the aid of multiple specialized working groups. This paper presents the current development status in terms of the architecture and functionality of OPIS. Possible implementation approaches for OPIS are also discussed.

Oxygen adsorption onto pure and doped Al surfaces--the role of surface dopants.

PubMed

Lousada, Cláudio M; Korzhavyi, Pavel A

2015-01-21

Using density functional theory (DFT) with the PBE0 density functional we investigated the role of surface dopants in the molecular and dissociative adsorption of O2 onto Al clusters of types Al50, Al50Alad, Al50X and Al49X, where X represents a dopant atom of the following elements Si, Mg, Cu, Sc, Zr, and Ti. Each dopant atom was placed on the Al(111) surface as an adatom or as a substitutional atom, in the last case replacing a surface Al atom. We found that for the same dopant geometry, the closer is the ionization energy of the dopant element to that of elemental Al, the more exothermic is the dissociative adsorption of O2 and the stronger are the bonds between the resulting O atoms and the surface. Additionally we show that the Mulliken concept of electronegativity can be applied in the prediction of the dissociative adsorption energy of O2 on the doped surfaces. The Mulliken modified second-stage electronegativity of the dopant atom is proportional to the exothermicity of the dissociative adsorption of O2. For the same dopant element in an adatom position the dissociation of O2 is more exothermic when compared to the case where the dopant occupies a substitutional position. These observations are discussed in view of the overlap population densities of states (OPDOS) computed as the overlap between the electronic states of the adsorbate O atoms and the clusters. It is shown that a more covalent character in the bonding between the Al surface and the dopant atom causes a more exothermic dissociation of O2 and stronger bonding with the O atoms when compared to a more ionic character in the bonding between the dopant and the Al surface. The extent of the adsorption site reconstruction is dopant atom dependent and is an important parameter for determining the mode of adsorption, adsorption energy and electronic structure of the product of O2 adsorption. The PBE0 functional could predict the existence of the O2 molecular adsorption product for many of the cases investigated here.

The abundance and relative volatility of refractory trace elements in Allende Ca,Al-rich inclusions - Implications for chemical and physical processes in the solar nebula

NASA Technical Reports Server (NTRS)

Kornacki, Alan S.; Fegley, Bruce, Jr.

1986-01-01

The relative volatilities of lithophile refractory trace elements (LRTE) were determined using calculated 50-percent condensation temperatures. Then, the refractory trace-element abundances were measured in about 100 Allende inclusions. The abundance patterns found in Allende Ca,Al-rich inclusions (CAIs) and ultrarefractory inclusions were used to empirically modify the calculated LRTE volatility sequence. In addition, the importance of crystal-chemical effects, diffusion constraints, and grain transport for the origin of the trace-element chemistry of Allende CAIs (which have important implications for chemical and physical processes in the solar nebula) is discussed.

Petrologic Consequences of the Magmatic Death of a Continental Arc: Vanda Dike Swarm, Dry Valleys, Antarctica

NASA Astrophysics Data System (ADS)

Harpp, K. S.; Christensen, B. C.; Geist, D. J.; Garcia, M. O.

2005-12-01

The Dry Valleys of southern Victoria Land, Antarctica, are notable for the presence of the Vanda dikes, prominent NE-trending swarms that crosscut a sequence of granitoid plutons. These older plutons are regional in extent and comprise 3 Cambro-Ordovician groups, including: a) calc-alkaline granitoids formed at an active plate margin during the Ross Orogeny (c. 505 Ma); b) adakitic granitoids, likely marking the conclusion of Ross Orogeny subduction-related activity (c. 490 Ma); and c) younger monzonitic plutons, probably generated in an intraplate extensional setting (Cox et al., 2000). The Vanda dikes crosscut the younger plutons, possibly between c. 490 and 477 Ma (Allibone et al., 1993; Encarnacion and Grunow, 1996). Dikes from the east wall of Bull Pass and the south wall of the Wright Valley range from 0.5-25 m wide with nearly vertical dips, are usually several km long, and, in the center of the swarms, occur with a frequency of ~18 dikes/km. Most have chilled margins and are surrounded by brittle fractures, indicative of shallow intrusion into cold country rock. Dike compositions are bimodal, most defining a trend at the boundary between the high-K calc-alkaline and shoshonite series in SiO2-K2O space; some Wright Valley dikes have slightly lower K2O and are calc-alkaline. Granite porphyry dikes are relatively homogeneous (69-73 wt.% SiO2), whereas the mafic dikes exhibit a wider range of compositions (49-57 wt.% SiO2). The felsic and mafic dikes have distinct trace element abundances but similar normalized distribution patterns, including fractionated heavy rare earth elements and negative Eu and high field-strength element anomalies. Average Sr/Y ratios of both the felsic and mafic dikes cluster around 20, well below a typical adakite signature. Major and trace element variations suggest that the felsic dikes may be differentiates of the mafic magmas. Field relations further indicate that the felsic lavas may represent, on average, a later phase of dike intrusion (Keiller, 1988; Allibone et al., 1993). The high-K calc-alkaline Vanda dike swarm likely represents the last phase of magmatism in a dying continental arc, perhaps accompanied by extension and uplift of the orogen. The relatively alkaline compositions of the dikes may result from lower degrees of melting, as subduction waned. References: Allibone, AH et al., New Zealand J of Geology and Geophysics, 36: 281-297, 1993. Cox, SC et al., New Zealand J of Geology and Geophysics, 43: 501-520, 2000. Encarnacion, J and Grunow, A, Tectonics, 15: 1325-1341, 1996. Keiller, IG, New Zealand Antarctic Record, 8: 25-34, 1988.

Evaluating Local and Regional Sources of Trace Element Contamination in a Rural Sub Estuary of the Upper Chesapeake Bay

NASA Astrophysics Data System (ADS)

Krahforst, C.; Hartman, S.; Sherman, L.; Kehm, K.

2014-12-01

The distribution of trace elements (V, Cr, Co, Ni, Cu, Zn, As, Ag, Cd, Sn, Ba, W, Pb and U) along with Al and Fe and other sediment characteristics in surface sediment and sediment cores from the Chester River - a sub estuary of the Chesapeake Bay located in a predominantly agricultural watershed of Maryland's upper Eastern Shore, USA - have been determined in order to add to the understanding of contaminant transport and fate and inform management strategies designed to maintain or improve the ecological condition of estuaries. These analyses coupled with the comparison of elemental analysis of 210Pb - dated sediment cores, main stem water quality surveys, and a review of recent EPA National Coastal Condition Assessment sediment data from Chesapeake Bay provide added information about the roles of local and region scale processes on ecosystem condition. The high amount of suspended sediment in the Chester River (5-20 mg L-1) is an important factor controlling water quality conditions of the Chester River and a prime focus for environmental management of this system. Sources of suspended matter include local runoff, atmospheric deposition, local resuspension, and exchange with the Chesapeake Bay. In principle, each of these sources could be distinguished on the basis of chemical composition of surface sediment. Preliminary results from multivariate analytic models indicate that many of the elements investigated display significant covariance with Al (and other predominantly crustal signatures) which may indicate limited exogenic sources of contamination for sediments of this watershed. For example total Pb concentrations are mostly below the NOAA's low toxic effects level and lower than the median value of NCCA data for the upper Chesapeake suggesting that sediments have significant sources from within the watershed. Further, significant higher concentrations of Sn and Cu coincide with sediment collected in or near marinas and point to localized anthropogenic sources for these elements. Elemental enrichment values relative to Al of Chester River sediments are significantly lower than observations in sediments from Chesapeake Bay overall and may indicate that local watershed management strategies may be effective for improving water and habitat quality of the Chester River.

Synthesis and characterization of CuAlO(2) and AgAlO(2) delafossite oxides through low-temperature hydrothermal methods.

PubMed

Xiong, Dehua; Zeng, Xianwei; Zhang, Wenjun; Wang, Huan; Zhao, Xiujian; Chen, Wei; Cheng, Yi-Bing

2014-04-21

In this work, we present one-step low temperature hydrothermal synthesis of submicrometer particulate CuAlO2 and AgAlO2 delafossite oxides, which are two important p-type transparent conducting oxides. The synthesis parameters that affect the crystal formation processes and the product morphologies, including the selection of starting materials and their molar ratios, the pH value of precursors, the hydrothermal temperature, pressure, and reaction time, have been studied. CuAlO2 crystals have been synthesized from the starting materials of CuCl and NaAlO2 at 320-400 °C, and from Cu2O and Al2O3 at 340-400 °C, respectively. AgAlO2 crystals have been successfully synthesized at the low temperature of 190 °C, using AgNO3 and Al(NO3)3 as the starting materials and NaOH as the mineralizer. The detailed elemental compositions, thermal stability, optical properties, and synthesis mechanisms of CuAlO2 and AgAlO2 also have been studied. Noteworthy is the fact that both CuAlO2 and AgAlO2 can be stabilized up to 800 °C, and their optical transparency can reach 60%-85% in the visible range. Besides, it is believed the crystal formation mechanisms uncovered in the synthesis of CuAlO2 and AgAlO2 will prove insightful guildlines for the preparation of other delafossite oxides.

Accumulation of elements by edible mushroom species II. A comparison of aluminium, barium and nutritional element contents.

PubMed

Mleczek, Mirosław; Siwulski, Marek; Stuper-Szablewska, Kinga; Sobieralski, Krzysztof; Magdziak, Zuzanna; Goliński, Piotr

2013-01-01

The aim of the study was to compare accumulation efficiency of Al, Ba and nutritional elements (Ca, Fe, K, Mg, Mn, Na) exhibited by six edible mushrooms collected in particular regions of Poland during the last 20 years. The studied mushroom species were Boletus edulis, Cantharellus cibarius, Lactarius deliciosus, Leccinum aurantiacum, Suillus luteus and Xerocomus badius. The highest and the lowest concentrations of the elements in tested mushroom species were 11 - 410, 34 - 337, 16785 - 34600, 140 - 607, 12 - 75 and 16 - 143 mg kg(-1)d.m., respectively. The highest average concentrations of Al, Mg and Mn were observed in Suillus luteus fruiting bodies, while for Ba, Ca, K and Na it was in Lactarius deliciosus. BCF >1 was found for K and Mg in all tested mushroom species and additionally for the highest Ca and Na concentrations of all tested mushroom species except for C. cibarius and S. luteus, respectively. For the other tested elements (Al, Ba, Fe and Mn) BCF values < 1 were recorded.

Analysis of some chosen elements of cerebrospinal fluid and serum in amyotrophic lateral sclerosis patients by total reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Ostachowicz, B.; Lankosz, M.; Tomik, B.; Adamek, D.; Wobrauschek, P.; Streli, C.; Kregsamer, P.

2006-11-01

Trace elements play an important role in the human central nervous system. Significant variations of the concentration of trace elements in body fluids may occur in neurodegenerative diseases. In the present work an investigation of the elemental composition of the serum, and the cerebrospinal fluid in amyotrophic lateral sclerosis patients and a control group was performed. For the analysis of the body fluids Total reflection X-ray Fluorescence (TXRF) spectrometry was used. The samples were taken during routine diagnostic procedures. Na, Mg, Cl, K, Ca, Cu, Zn, and Br were determined in both fluids. In order to validate the results of analysis a serum standard reference material was measured. A t-test was applied to check if the mean concentrations of the elements are different for ALS and the control group. For the serum samples higher values for Br were found in the ALS group, for the cerebrospinal fluid lower values of Na, Mg and Zn as well as higher Ca values were found in the ALS group compared to the control group.

Earth's Archean Impact Record In The ICDP Drilling "Barberton Mountain Land".

NASA Astrophysics Data System (ADS)

Fritz, Jörg; Schmitt, Ralf-Thomas; Reimold, Uwe; Koeberl, Christian; Mc Donald, Ian; Hofmann, Axel; Luais, Beatrice

2013-04-01

The marine meta-sedimentary successions in the "Barberton Mountain Land" are formed by Archean volcanic and sedimentary rocks including the oldest known impact ejecta layers on Earth. The chemical signature (high iridium concentrations, chromium isotopic ratios) of some of these up to tens of cm thick Archean spherule layers advocate that these ejecta deposits represent mainly extraterrestrial material [1]. These ejecta layers contain millimetre sized spherules that are larger and accumulated thicker layers compared to any impact ejecta layer known from Phanerozoic sediments, including the global ejecta layer of the Chicxulub impact catering event terminating the Mesozoic era of Earth's history [2]. The Archean spherule layers are interpreted as products of large impacts by 20 to >100 km diameter objects [3, 4]. Identifying traces of mega-impacts in Earth's ancient history could be of relevance for the evolution of atmosphere, biosphere, and parts of the Earth's crust during that time. In addition, recognizing global stratigraphic marker horizons is highly valuable for inter-correlating sedimentary successions between Archean cratons [5]. However estimates regarding size of the impact event and correlations between the different outcrops in the Barberton mountain land are complicated by post depositional alterations of the tectonically deformed sediments [6, 7]. The relatively fresh samples recovered from below the water table during the 2011-2012 ICDP drilling "Barberton Mountain Land" are promising samples to investigate and to discriminate primary and secondary features of these rare rocks. We plan to conduct 1) petrographic, micro-chemical and mineralogical characterization of the impact ejecta layers, 2) bulk chemical analyses of major and trace elements, and 3) LAICP- MS elemental mapping of platinum group element (PGE) distributions. and elemental analyses of moderately siderophile elements. This aims at 1) characterization of the ejecta layers, 2) identification of the phases hosting the extraterrestrial PGE signature, 3) discrimination of the primary geological evidence of the impact event from those characteristics that resulted from syn- and post-sedimentary alteration. Acknowledgement: Financial support by the DFG - RE 528/14-1. References: [1] Lowe D. R. et al. (2003) Astrobiology 3, 7-47. [2] Simonson B. M. and Harnik P. (2000) Geology 28, 975-978. [3] Lowe D. R. and Byerly G. R. (1986) Geology 14, 83-86. [4] Melosh H. J. and Vickery A. M. (1991) Nature 350, 494-497. [5] Byerly G. R. et al. (2002) Science 297, 1325-1327. [6] Reimold W. U. et al. (2000) Impacts and the Early Earth. Eds.: Gilmour I., Koeberl C. Lecture Notes in Earth Sciences 91, Springer-Verlag, Berlin, pp.117-180. [7] Hofmann A. et al. (2006) GSA Special Paper 405, 33 - 56.

Experimental Study into the Partitioning Behavior of Fluorine, Chlorine, Hydroxyl, and Sulfur (S2-) Between Apatite and a Synthetic Kreep Basalt Melt

NASA Technical Reports Server (NTRS)

Turner, Amber; Vander Kaaden, Kathleen; McCubbin, Francis; Danielson, Lisa R.

2017-01-01

The mineral apatite (Ca5 (PO4)3(F, Cl, OH)) is known for its ability to constrain the petrogenesis of the rock in which it is hosted and for its ubiquity throughout the Solar System, as it is found in lunar, martian, and terrestrial rocks alike (McCubbin et. al, 2015). The abundance of volatile elements, and for this particular study, the elevated abundance of sulfur (S2-) in high-Al basalt samples bearing apatite, could provide more insight for inquiries posed about the behavior of volatiles in lunar and martian magmatic systems (Boyce et. al, 2010). Oxygen fugacity will be an important parameter for these experiments, as the Moon, Mars, and Earth have different redox states (Herd, 2008). The objective of this experimental endeavor is to determine apatite-melt partition coefficients for the volatile elements (F-, Cl-, OH-, S2-) that make up the X-site (i.e., the typically monovalent anion site) in the mineral apatite in a lunar melt composition under lunar oxygen fugacity conditions approx.1-2 log units below the iron-wüstite buffer). All experiments will be conducted at NASA, Johnson Space Center in the High Pressure Experimental Petrology Laboratory. In order to conduct apatite-melt partition experiments with oxygen fugacity as an additional parameter, we will create a synthetic mix of the lunar KREEP basalt 15386, a sample retrieved during Apollo 15 that is believed to represent an indigenous volcanic melt derived from the lunar interior (Rhodes, J.M et. al, 2006). Other geochemically significant elements including C, Co, Ni, Mo, and rare earth elements will be included in the mix at trace abundances in order to assess their partitioning behavior without effecting the overall behavior of the system. The synthetic mix will then be loaded into a piston cylinder, an apparatus used to simulate high-pressure/high-temperature conditions of planetary interiors, and exposed to 0.5 GPa of pressure, the pressure observed in the upper mantle of the Moon, and heated to the melting temperature of the materials. To make sure crystals grow large enough for the necessary analyses, the sample will be kept at the crystallization temperature for 8 hours. This extended run time should also allow the sample to achieve a steady state which is necessary to accurately assess the partitioning of these elements between apatite and melt. The results from this experimental study will allow us to determine the fate of F-, Cl-, OH-, and S2- during the magmatic evolution of the Moon.

Surface chemistry of the Moon: New views from Chandrayaan-1 X-ray Spectrometer and future potentials

NASA Astrophysics Data System (ADS)

Narendranath, Shyama; Athiray, Subramania; Parameswaran, Sreekumar; Grande, Manuel

2015-04-01

X-ray remote sensing is an established technique for chemical mapping of atmosphere-less inner solar system bodies. Chandrayaan-1 X-ray Spectrometer (C1XS) [Grande et al, 2009], on-board the first Indian lunar mission Chandrayaan-1 [Bhandari et al, 2004], was flown with the objective [Crawford et al, 2009] of globally mapping the abundances of the major rock-forming elements Mg, Al, Si, Ca ,Ti and Fe with a spatial resolution of 25 km on the lunar surface. The instrument was developed by the Rutherford Appleton Laboratory (RAL), UK in collaboration with the Indian Space Research Organization (ISRO). X-ray fluorescence (XRF) observations measure the abundance irrespective of the mineral structure. XRF spectral analysis can uniquely identify and quantify elemental signatures from all commonly occurring elements. C1XS is one of the first instruments to unambiguously map the abundance of elements from Na to Fe at scales of tens of kilometers. Because of the exceptionally low solar activity in 2009, the strongest solar flare observed was of C3 class and hence global mapping could not be achieved. However from the available coverage of ~ 5%, we have determined elemental abundances accurately through a detailed calibration of the instrument and inversion methodology [Narendranath et al, 2010; Athiray et al, 2013]. The end-to-end capacity to derive independent and accurate global surface chemical abundances using x-ray signatures was clearly demonstrated with C1XS. We present results from a comprehensive analysis of all data from C1XS with emphasis on the new finding of enhanced sodium in the southern lunar highlands that suggests possible new lithologies [Narendranath et al, 2011; Athiray et al, 2014]. It is generally believed that lunar highlands are mainly composed of plagioclase feldspar with lower amounts of the mafic minerals. Plagioclase in lunar samples have been found to have an anorthite content as high as An98 with the average highlands estimated to be An95. Lower anorthite content (as low as An70) plagioclase grains have been found in lunar samples but is much rarer. C1XS measurements especially of Na, Al and Ca reveal larger regions of low An than previously thought of. We provide evidence for this from quantitative estimates of elemental abundances. Further, we present the development of Chandrayaan-2 Large Area Soft x-ray Spectrometer (CLASS) [Narendranath et al, 2014] to be flown on the second Indian lunar mission (~2018) which would continue from where C1XS left off but with a greater sensitivity and better spatial resolution.

Forbidden line emission from highly ionized atoms in tokamak plasmas

NASA Technical Reports Server (NTRS)

Feldman, U.; Doschek, G. A.; Bhatia, A. K.

1982-01-01

Considerable interest in the observation of forbidden spectral lines from highly ionized atoms in tokamak plasmas is related to the significance of such observations for plasma diagnostic applications. Atomic data for the elements Ti Cr, Mn, Fe, Ni, and Kr have been published by Feldman et al. (1980) and Bhatia et al. (1980). The present investigation is concerned with collisional excitation rate coefficients and radiative decay rates, which are interpolated for ions of elements between calcium, and krypton and for levels of the 2s2 2pk, 2s 2p(k+1), and 2p(k+2) configurations, and for the O I, N I, C I, B I, and Be I isoelectronic sequences. The provided interpolated atomic data can be employed to calculate level populations and relative line intensities for ions of the considered sequences, taking into account levels of the stated configurations. Important plasma diagnostic information provided by the forbidden lines includes the ion temperature

Geochemical studies of the White Breccia Boulders at North Ray Crater, Descartes region of the lunar highlands

NASA Technical Reports Server (NTRS)

Lindstrom, M. M.; Lindstrom, D. J.; Lum, R. K. L.; Schuhmann, P. J.; Nava, D. F.; Schuhmann, S.; Philpotts, J. A.; Winzer, S. R.

1977-01-01

The samples of the White Breccia Boulders obtained during the Apollo 16 mission and investigated in the reported study include an anorthositic breccia (67415), a dark matrix breccia (67435), a light matrix breccia (67455), and a large clast of dark matrix breccia (67475) taken from the 67455 boulder. The chemical analyses of bulk samples of the samples are listed in a table. A graph shows the lithophile trace element abundances. Another graph indicates the variation of Sm with Al2O3 content for samples from the White Breccia Boulders. The North Ray Crater breccias are found to be in general slightly more aluminous than breccias from the other stations at the Apollo 16 site. Analyses of eight Apollo 16 breccias cited in the literature range from 25% to 35% Al2O3. However, the North Ray Crater breccias are more clearly distinct from the other Apollo 16 breccias in their contents of lithophile trace elements.

The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-Au deposit, Tongling ore district, Anhui Province, Eastern China

NASA Astrophysics Data System (ADS)

Xiao, Xin; Zhou, Tao-fa; White, Noel C.; Zhang, Le-jun; Fan, Yu; Wang, Fang-yue; Chen, Xue-feng

2018-03-01

Xinqiao is a large copper-gold deposit and consists of two major mineralization types: stratabound and skarn. The skarn occurs along the contact between a quartz diorite intrusion and Carboniferous-Triassic limestone. Xinqiao has a strongly developed skarn zone, including endoskarn and exoskarn; the exoskarn is divided into proximal and distal exoskarn. We present systematic major, trace and rare earth element (REE) concentrations for garnets from the skarn zone, discuss the factors controlling the incorporation of trace elements into the garnets, and constrain the formation and evolution of the garnet from skarn zone in Xinqiao deposit. Grossular (Adr20-44Grs56-80) mostly occurs in endoskarn and has typical HREE-enriched and LREE-depleted patterns, with small Eu anomalies and low ∑REE. Garnets from the exoskarn show complex textures and chemical compositions. The composition of garnets range from Al-rich andradite (Adr63-81Grs19-47) to andradite (Adr67-98Grs2-33). Garnet in endoskarn has typical HREE-enriched and LREE-depleted patterns. Al-rich andradite in proximal skarn has small Eu anomalies and moderate ∑REE. Andradite from distal exoskarn shows strong positive Eu anomalies and has variable ∑REE. The U, Y, Fe and Al relationship with ∑REE shows that two mechanisms controlled incorporation of REE into the garnets: crystal chemistry (substitution and interstitial solid solution) mainly controlled in the endoskarn garnet (grossular) and the proximal exoskarn (Al-rich andradite), and fluid and rock chemistry (surface adsorption and occlusion) controlled REEs in the distal exoskarn. Furthermore, Al has a negative relationship with ∑REE indicating that REE3+ did not follow a coupled, YAG-type substitution into the garnets. Variations in textures and trace and rare earth elements of garnets suggest that the garnets in the endoskarn formed by slow crystal growth at low W/R ratios and near-neutral pH in a closed system during periods of diffusive metasomatism. The garnets in the exoskarn formed rapidly from externally derived fluids during advective metasomatism, and adsorption had a major control on the REE patterns in distal exoskarn. With the end of water-rock reaction, the contents of REE decreased in the hydrothermal fluid, and the system became nearly closed.

Architecture and Functionality of the Advanced Life Support On-Line Project Information System (OPIS)

NASA Technical Reports Server (NTRS)

Hogan, John A.; Levri, Julie A.; Morrow, Rich; Cavazzoni, Jim; Rodriquez, Luis F.; Riano, Rebecca; Whitaker, Dawn R.

2004-01-01

An ongoing effort is underway at NASA Amcs Research Center (ARC) tu develop an On-line Project Information System (OPIS) for the Advanced Life Support (ALS) Program. The objective of this three-year project is to develop, test, revise and deploy OPIS to enhance the quality of decision-making metrics and attainment of Program goals through improved knowledge sharing. OPIS will centrally locate detailed project information solicited from investigators on an annual basis and make it readily accessible by the ALS Community via a web-accessible interface. The data will be stored in an object-oriented relational database (created in MySQL(Trademark) located on a secure server at NASA ARC. OPE will simultaneously serve several functions, including being an R&TD status information hub that can potentially serve as the primary annual reporting mechanism. Using OPIS, ALS managers and element leads will be able to carry out informed research and technology development investment decisions, and allow analysts to perform accurate systems evaluations. Additionally, the range and specificity of information solicited will serve to educate technology developers of programmatic needs. OPIS will collect comprehensive information from all ALS projects as well as highly detailed information specific to technology development in each ALS area (Waste, Water, Air, Biomass, Food, Thermal, and Control). Because the scope of needed information can vary dramatically between areas, element-specific technology information is being compiled with the aid of multiple specialized working groups. This paper presents the current development status in terms of the architecture and functionality of OPIS. Possible implementation approaches for OPIS are also discussed.

The use of multifractal modelling for targeting resources from soil and stream geochemistry data: the case of the Variscan basement of the Iberian Peninsula

NASA Astrophysics Data System (ADS)

Gonçalves, Mario; Mateus, Antonio

2016-04-01

The safeguarding of access/use of many critical raw materials for Society requires that much of previously dismissed areas for exploration must be re-evaluated with new criteria in which the significance of "anomaly" should not be treated independently of the geochemical signals of the ore-forming processes and how the different chemical elements are interrelated. For much of the previous decade, several multifractal methods were methodically being refined as automatic tools to analyze and detect geochemical anomalies. These included the early concentration-area method (Cheng et al., 1994), singularity mapping (Cheng, 2007), and spectrum-area (Cheng et al., 2000), which has been recently combined with the bi-dimensional empirical mode decomposition (Xu et al., 2016) as a tool to separate different contributing sources of an otherwise complex geochemical pattern. We propose yet another approach, the use of geochemical indexes, which links to the geological and ore-forming processes known to define a given region in order to assess much of these numerical approaches. Therefore, we picked several areas from the Variscan basement in Portugal, with different geologic and metallogentic contexts, some of them previously analyzed with multifractal methods (Gonçalves et al., 2001; Jesus et al., 2013) and a multi-element geochemical campaign on which to test the different multifractal methods combined with the geochemical indexes, as an advantageous alternative to principal component mapping, for example. Some preliminary essays with stochastic models similar to those reported in Gonçalves (2001) and Agterberg (2007), with different overprinted pulses are presented as well. Acknowledgments: This is a contribution from UID/GEO/50019/2013 - Instituto Dom Luiz, supported by FCT. Agterberg, 2007, Math. Geol., 39, 1. Cheng et al, 1994, J. Geochem. Explor., 51, 109. Cheng et al., 2000, Nat. Resour. Res, 9, 43. Cheng, 2007, Ore Geol. Rev., 32, 314. Gonçalves, 2001, Math. Geol., 33, 41. Gonçalves et al., 2001, J. Geochem. Explor., 72, 91. Jesus et al., 2013, J. Geochem. Explor., 126-127, 23. Xu et al., 2016, J. Geochem. Explor., in press

Einsteinium

NASA Astrophysics Data System (ADS)

Haire, Richard G.

The discovery of einsteinium, element 99, came about during the analyses of nuclear products produced in and then recovered from test debris following a thermonuclear explosion (weapon test device, ‘Mike', November 1952) at Eniwetok Atoll in the Pacific Ocean. The uranium present in this device was subjected to a very intense neutron flux (integrated fluence of about 1024neutrons) in an extremely short time frame (few nanoseconds), which allowed a large number of multiple neutron captures with a minimal degree of decay of the products formed. Nuclei were formed with usually high neutron/proton ratios (very ‘heavy' uranium isotopes), which then rapidly beta-decayed into new, transuranium isotopes through element 100. Scientists from several U.S. Government laboratories separated and analyzed extensively the debris samplings in the following weeks. From these investigations came the discovery and identification of einsteinium and fermium. The first element was named in honor of Albert Einstein, and assigned the symbol, E (later changed to the current symbol, Es). Additional details and discussions about the discovery of this element and the scientists involved are given in several references (Thompson et al., 1954; Ghiorso et al., 1955; Fields et al., 1956; Hyde et al., 1964; Seaborg and Loveland, 1990).

A geochemical assessment of possible lunar ore formation

NASA Technical Reports Server (NTRS)

Haskin, Larry A.; Colson, Russell O.; Vaniman, David

1991-01-01

The Moon apparently formed without appreciable water or other relatively volatile materials. Interior concentrations of water or other volatile substances appear to be extremely low. On Earth, water is important to the genesis of nearly all types of ores. Thus, some have reasoned that only abundant elements would occur in ore concentrations. The definition and recognition of ores on the Moon challenge the imaginations and the terrestrial perceptions of ore bodies. Lunar ores included solar-wind soaked soils, which contain abundant but dilute H, C, N, and noble gases (including He-3). Oxygen must be mined; soils contain approximately 45 percent (wt). Mainstream processes of rock formation concentrated Si, Mg, Al, Fe, and Ca, and possibly Ti and Cr. The highland surface contains approximately 70 percent (wt) feldspar (mainly CaAl2Si2O8), which can be separated from some highland soils. Small fragments of dunite were collected; dunite may occur in walls and central peaks of some craters. Theoretical extensions of observations of lunar samples suggest that the Moon may have produced ores of trace elements. Some small fragments have trace-element concentrations 10(exp 4) times higher than the lunar average, indicating that effective geochemical separations occurred; processes included fractional crystallization, silicate immiscibility, vaporization and condensation, and sulfide metamorphism. Operations of these processes acting on indigenous materials and on meteoritic material in the regolith could have produced ores. Infalling carbonaceous meteorites and comets have added water and hydrocarbons that may have been cold-trapped. Vesicles in basalts, pyroclastic beads, and reported transient events suggest gag emission from the lunar interior; such gas might concentrate and transport rare elements. Large impacts may disperse ores or produce them through deposition of heat at depth and by vaporization and subsequent condensation. The main problem in assessing lunar resources is the ignorance about the largely unexplored Moon.

Exploring the uncertainty in attributing sediment contributions in fingerprinting studies due to uncertainty in determining element concentrations in source areas.

NASA Astrophysics Data System (ADS)

Gomez, Jose Alfonso; Owens, Phillip N.; Koiter, Alex J.; Lobb, David

2016-04-01

One of the major sources of uncertainty in attributing sediment sources in fingerprinting studies is the uncertainty in determining the concentrations of the elements used in the mixing model due to the variability of the concentrations of these elements in the source materials (e.g., Kraushaar et al., 2015). The uncertainty in determining the "true" concentration of a given element in each one of the source areas depends on several factors, among them the spatial variability of that element, the sampling procedure and sampling density. Researchers have limited control over these factors, and usually sampling density tends to be sparse, limited by time and the resources available. Monte Carlo analysis has been used regularly in fingerprinting studies to explore the probable solutions within the measured variability of the elements in the source areas, providing an appraisal of the probability of the different solutions (e.g., Collins et al., 2012). This problem can be considered analogous to the propagation of uncertainty in hydrologic models due to uncertainty in the determination of the values of the model parameters, and there are many examples of Monte Carlo analysis of this uncertainty (e.g., Freeze, 1980; Gómez et al., 2001). Some of these model analyses rely on the simulation of "virtual" situations that were calibrated from parameter values found in the literature, with the purpose of providing insight about the response of the model to different configurations of input parameters. This approach - evaluating the answer for a "virtual" problem whose solution could be known in advance - might be useful in evaluating the propagation of uncertainty in mixing models in sediment fingerprinting studies. In this communication, we present the preliminary results of an on-going study evaluating the effect of variability of element concentrations in source materials, sampling density, and the number of elements included in the mixing models. For this study a virtual catchment was constructed, composed by three sub-catchments each of 500 x 500 m size. We assumed that there was no selectivity in sediment detachment or transport. A numerical excercise was performed considering these variables: 1) variability of element concentration: three levels with CVs of 20 %, 50 % and 80 %; 2) sampling density: 10, 25 and 50 "samples" per sub-catchment and element; and 3) number of elements included in the mixing model: two (determined), and five (overdetermined). This resulted in a total of 18 (3 x 3 x 2) possible combinations. The five fingerprinting elements considered in the study were: C, N, 40K, Al and Pavail, and their average values, taken from the literature, were: sub-catchment 1: 4.0 %, 0.35 %, 0.50 ppm, 5.0 ppm, 1.42 ppm, respectively; sub-catchment 2: 2.0 %, 0.18 %, 0.20 ppm, 10.0 ppm, 0.20 ppm, respectively; and sub-catchment 3: 1.0 %, 0.06 %, 1.0 ppm, 16.0 ppm, 7.8 ppm, respectively. For each sub-catchment, three maps of the spatial distribution of each element was generated using the random generator of Mejia and Rodriguez-Iturbe (1974) as described in Freeze (1980), using the average value and the three different CVs defined above. Each map for each source area and property was generated for a 100 x 100 square grid, each grid cell being 5 m x 5 m. Maps were randomly generated for each property and source area. In doing so, we did not consider the possibility of cross correlation among properties. Spatial autocorrelation was assumed to be weak. The reason for generating the maps was to create a "virtual" situation where all the element concentration values at each point are known. Simultaneously, we arbitrarily determined the percentage of sediment coming from sub-catchments. These values were 30 %, 10 % and 60 %, for sub-catchments 1, 2 and 3, respectively. Using these values, we determined the element concentrations in the sediment. The exercise consisted of creating different sampling strategies in a virtual environment to determine an average value for each of the different maps of element concentration and sub-catchment, under different sampling densities: 200 different average values for the "high" sampling density (average of 50 samples); 400 different average values for the "medium" sampling density (average of 25 samples); and 1,000 different average values for the "low" sampling density (average of 10 samples). All these combinations of possible values of element concentrations in the source areas were solved for the concentration in the sediment already determined for the "true" solution using limSolve (Soetaert et al., 2014) in R language. The sediment source solutions found for the different situations and values were analyzed in order to: 1) evaluate the uncertainty in the sediment source attribution; and 2) explore strategies to detect the most probable solutions that might lead to improved methods for constructing the most robust mixing models. Preliminary results on these will be presented and discussed in this communication. Key words: sediment, fingerprinting, uncertainty, variability, mixing model. References Collins, A.L., Zhang, Y., McChesney, D., Walling, D.E., Haley, S.M., Smith, P. 2012. Sediment source tracing in a lowland agricultural catchment in southern England using a modified procedure combining statistical analysis and numerical modelling. Science of the Total Environment 414: 301-317. Freeze, R.A. 1980. A stochastic-conceptual analysis of rainfall-runoff processes on a hillslope. Water Resources Research 16: 391-408.

Corrosion behavior in high-temperature pressurized water of Zircaloy-4 joints brazed with Zr-Cu-based amorphous filler alloys

NASA Astrophysics Data System (ADS)

Lee, Jung Gu; Lee, Gyoung-Ja; Park, Jin-Ju; Lee, Min-Ku

2017-05-01

The compositional effects of ternary Zr-Cu-X (X: Al, Fe) amorphous filler alloys on galvanic corrosion susceptibility in high-temperature pressurized water were investigated for Zircaloy-4 brazed joints. Through an Al-induced microgalvanic reaction that deteriorated the overall nobility of the joint, application of the Zr-Cu-Al filler alloy caused galvanic coupling to develop readily between the Al-bearing joint and the Al-free base metal, finally leading to massive localized corrosion of the joint. Contrastingly, joints prepared with a Zr-Cu-Fe filler alloy showed excellent corrosion resistance comparable to that of the Zircaloy-4 base metal, since the Cu and Fe elements forming fine intermetallic particles with Zr did not influence the electrochemical stability of the resultant joints. The present results demonstrate that Fe is a more suitable alloying element than Al for brazing filler alloys subjected to high-temperature corrosive environments.

Migration laws of major elements of Laowashan bauxite in Zunyi area, northern Guizhou province of China

NASA Astrophysics Data System (ADS)

Cui, Tao

2018-01-01

After exploring migration laws of major elements in Laowashan bauxite of northern Guizhou Province by geochemical methods, it was found that: 1) Si was negatively correlated to Al and Ti; Al showed significant negative correlations with Si and Fe; Al was positively correlated to Ti. 2) The content of Si and Fe was low in the middle part, high at the top and the highest at the bottom. The content of Al and Ti is the highest in the middle, followed by the content at the top and the bottom successively. 3) Karst depressions are favorable for groundwater discharge through leaching, leading to heavy loss of Fe in ZK-CS1.

Irradiation of Wrought FeCrAl Tubes in the High Flux Isotope Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linton, Kory D.; Field, Kevin G.; Petrie, Christian M.

The Advanced Fuels Campaign within the Nuclear Technology Research and Development program of the Department of Energy Office of Nuclear Energy is seeking to improve the accident tolerance of light water reactors. Alumina-forming ferritic alloys (e.g., FeCrAl) are one of the leading candidate materials for fuel cladding to replace traditional zirconium alloys because of the superior oxidation resistance of FeCrAl. However, there are still some unresolved questions regarding irradiation effects on the microstructure and mechanical properties of FeCrAl at end-of-life dose levels. In particular, there are concerns related to irradiation-induced embrittlement of FeCrAl alloys due to secondary phase formation. Tomore » address this issue, Oak Ridge National Laboratory has developed a new experimental design to irradiate shortened cladding tube specimens with representative 17×17 array pressurized water reactor diameter and thickness in the High Flux Isotope Reactor (HFIR) under relevant temperatures (300–350°C). Post-irradiation examination will include studies of dimensional change, microstructural changes, and mechanical performance. This report briefly summarizes the capsule design concept and the irradiation test matrix for six rabbit capsules. Each rabbit contains two FeCrAl alloy tube specimens. The specimens include Generation I and Generation II FeCrAl alloys with varying processing conditions, Cr concentrations, and minor alloying elements. The rabbits were successfully assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. Pictures of the rabbit assembly process and detailed dimensional inspection of select specimens are included in this report. The rabbits were inserted into HFIR starting in cycle 472 (May 2017).« less

TIC/TOC and Redox Sensitive Trace Element (RSTEs) Signals Indicating Redox Conditions of the Lower Part of the Cabo Formation Near Organya (Organya Basin), Catalunya, Spain

NASA Astrophysics Data System (ADS)

Herdocia, C.; Maurrasse, F. J.

2017-12-01

The thick (> 4.5 km) sedimentary succession of the Organya Basin includes the Cabo Formation [1] which is well exposed in the Cabo valley area and is characteristically composed of black to dark gray marlstones and limestones that accumulated during the greenhouse climate and contain variable amount of organic matter [2-4]. Here we present geochemical results to assess redox conditions of 35.6 m of the Cabo Formation near the Barremian / Aptian boundary, along Catalunya Route C-14, immediately north of the town of Organya. TOC values range between 1 wt% and 5.8 wt%, and peak in all black limestones (0.43 m, 4.38 m, 14.85 m, 29.95 m, and 35.6 m). These TOC values average about 2.0 wt %, except at a height of 0.43 m, where the TOC has a strong peak (5.78 wt%). TIC values oscillated between 86.7 wt% and 96.8 wt%, and averaged at 92.7 wt% and show a strong negative correlation with TOC (r = -0.78). Measured carbon isotope on the organic carbon fraction (δ13Corg) showed fluctuations that ranged from -24.41‰ to -22.15‰. The TOC and δ13Corg curves show a positive correlation (r = 0.58), suggesting that carbon sequestration in the basin followed the overall global signature. Redox sensitive trace elements (V, Ni, Cu, and Mo) correlate with TOC values (r > 0.6), suggesting that dysoxic conditions were responsible for the preservation of organic matter. Biolimiting trace elements (Fe, P) also correlate positively with redox trace elements, and both have highest concentrations at 14.85 m, in concurrence with a high TOC value (2.93 wt%) indicating high primary productivity at that level. Major elements (Al, Si, and Ti) also correlates slightly with TOC (Al: r = 0.39; Si: r = 0.36; Ti: r = 0.43). References: [1] García-Senz, J., 2002, PhD Thesis, University of Barcelona, 310 pp. [2] Bernaus, J.M., et al., 2003. Sedimentary Geology 159 (3-4), 177-201. [3] Caus, E., et al., 1990. Cret. Research 11, 313-320. [4] Sanchez-Hernandez, Y., Maurrasse, F.J-M.R. 2014. Chem.Geology 372, 12-31.

Characteristics and environmental aspects of slag: a review

USGS Publications Warehouse

Piatak, Nadine M.; Parsons, Michael B.; Seal, Robert R.

2015-01-01

The composition of ferrous slag is dominated by Ca and Si. Steel slag may contain significant Fe, whereas Mg and Al may be significant in Fe slag. Calcium-rich olivine-group silicates, melilite-group silicates that contain Al or Mg, Ca-rich glass, and oxides are the most commonly reported major phases in ferrous slag. Calcite and trace amounts of a variety of sulfides, intermetallic compounds, and pure metals are typically also present. The composition of non-ferrous slag, most commonly from base-metal production, is dominated by Fe and Si with significant but lesser amounts of Al and Ca. Silicates in the olivine, pyroxene, and melilite groups, as well as glass, spinels, and SiO2 (i.e., quartz and other polymorphs) are commonly found in non-ferrous slag. Sulfides and intermetallic compounds are less abundant than the silicates and oxides. The concentrations of some elements exceed generic USEPA soil screening levels for human contact based on multiple exposure pathways; these elements include Al, Cr, Cu, Fe, Mn, Pb, and Zn based on bulk chemical composition. Each slag type usually contains a specific suite of elements that may be of environmental concern. In general, non-ferrous slag may have a higher potential to negatively impact the environment compared to ferrous slag, and is thus a less attractive material for reuse, based on trace element chemistry, principally for base metals. However, the amount of elements released into the environment is not always consistent with bulk chemical composition. Many types of leaching tests have been used to help predict slag’s long-term environmental behavior. Overall, ferrous slags produce an alkaline leachate due to the dissolution of Ca oxides and silicates derived from compounds originally added as fluxing agents, such as lime. Ferrous slag leachate is commonly less metal-rich than leachate from non-ferrous slag generated during base metal extraction; the latter leachate may even be acidic due to the oxidation of sulfides. Because of its characteristics, ferrous slag is commonly used for construction and environmental applications, whereas both non-ferrous and ferrous slag may be reprocessed for secondary metal recovery. Both types of slag have been a source of some environmental contamination. Research into the environmental aspects of slag will continue to be an important topic whether the goal is its reuse, recycling, or remediation.

Electronic circuits having NiAl and Ni.sub.3 Al substrates

DOEpatents

Deevi, Seetharama C.; Sikka, Vinod K.

1999-01-01

An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

Element uptake and physiological responses of Lactuca sativa upon co-exposures to tourmaline and dissolved humic acids.

PubMed

Jia, Weili; Wang, Cuiping; Ma, Chuanxin; Wang, Jicheng; Sun, Hongwen

2018-06-01

Element migration and physiological response in Lactuca sativa upon co-exposure to tourmaline (T) and dissolved humic acids (DHAs) were investigated. Different fractions of DHA 1 and DHA 4 and three different doses of T were introduced into Hoagland's solution. The results indicated that T enhanced the contents of elements such as N and C, Si and Al in the roots and shoots. The correlation between TF values of Si and Al (R 2  = 0.7387) was higher than that of Si and Mn (R 2  = 0.4961) without the presence of DHAs. However, both DHA 1 and DHA 4 increased the correlation between Si and Mn, but decreased the one between Si and Al. CAT activities in T treatments were positively correlated to the contents of N and Al in the shoots, whose R 2 was 0.9994 and 0.9897, respectively. In the co-exposure of DHAs and tourmaline, DHA 4 exhibited more impacts on element uptake, CAT activities, as well as ABA contents in comparison with the presence of DHA 1 , regardless of the T exposure doses. These results suggested that DHAs have effects on mineral element behaviors and physiological response in Lactuca sativa upon exposure to tourmaline for the first time, which had great use in guiding soil remediation.

Assessment of the analytical capabilities of inductively coupled plasma-mass spectrometry

USGS Publications Warehouse

Taylor, Howard E.; Garbarino, John R.

1988-01-01

A thorough assessment of the analytical capabilities of inductively coupled plasma-mass spectrometry was conducted for selected analytes of importance in water quality applications and hydrologic research. A multielement calibration curve technique was designed to produce accurate and precise results in analysis times of approximately one minute. The suite of elements included Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, Pb, Se, Sr, V, and Zn. The effects of sample matrix composition on the accuracy of the determinations showed that matrix elements (such as Na, Ca, Mg, and K) that may be present in natural water samples at concentration levels greater than 50 mg/L resulted in as much as a 10% suppression in ion current for analyte elements. Operational detection limits are presented.

Trace Element Geochemistry as a Tool for the Reconstruction of Upwelling Patterns at 12oS off Peru since the Last Glacial Maximum (LGM)

NASA Astrophysics Data System (ADS)

Boening, P.; Brumsack, H.; Wolf, A.

2002-05-01

Laminated sediments (core 106KL), recovered during R/V Sonne cruise 147 from the Peruvian upper slope mud lens at 12oS, were analyzed for bulk parameters (TOC, TIC, TS) and opal as well as major and trace element composition by XRF and ICP-MS in 5 cm intervals. The composition of the terrigenous-detrital sediment fraction is comparable to average shale. The sediments exhibit slight increases in biogenic silica (diatoms) and carbonate contents (foraminifera) in varying layers. The experimentally determined opal contents correlate well with Si/Al ratios. High TOC and P contents are due to enhanced primary productivity, high sedimentation rates and corresponding organic matter preservation under a strong OMZ. We distinguish between three different groups of elements: 1.) trace elements involved in bio-cycling (e.g. Cd, Ag, Ni, Cu) are highly enriched in the sediments due to their association with plankton, high sedimentation rates (preventing remobilization from the sediments) and fixation as sulfides. 2.) redox-sensitive elements (e.g. Re, Mo) are significantly enriched probably due to reduction and precipitation under suboxic/anoxic conditions. Diffusion of these elements from the water column into sub/anoxic sediments seems to be the controlling factor, besides sulfide precipitation. An average Re/Mo ratio of 1.3 indicates anoxic sedimentary conditions. Most trace elements correlate well with the TOC content presumably documenting productivity events. 3.) Al, Zr and Y are well correlated, presumably representing sporadic high-energy fluvial input from the continent or enhanced current velocities. The three element groups were used to reconstruct the upwelling patterns off Lima since the LGM: TOC content and Al-normalized trace element patterns from the bio/redox-sensitive fractions represent the signal from the water column, whereas Al, Y and Zr reflect the terrigenous input. During the LGM (about 17 ky BP) the site was hardly affected by upwelling as the upwelling cell was located more basinward. As the sea level rose during the Late Glacial (17-10 ky BP) the upwelling cell shifted towards the coast. The Early Holocene (10-5 ky BP) is not documented likely because strong currents (presumably the Peru counter current) eroded the slope. In the Late Holocene the upwelling cell was established at the site. However, a higher terrrigenous proportion and lower input from the water column suggest a basinward shifting of the upwelling cell during the Second Neoglacial (2000-2700 BP). Stronger Element/Al and TOC variabilities indicate the influence of El Nino during the Late Holocene.

Phase constitution in the interfacial region of laser penetration brazed magnesium–steel joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Yugang; Han, Duanfeng, E-mail: handuanfeng@gmail.com; Xu, Xiangfang

2014-07-01

The phase constitution in the interfacial region of laser penetration brazed magnesium–steel joints was investigated using electron microscopy. From the distribution of elements, the transition zone was mainly composed of elements Mg and Fe along with some Al and O. Furthermore, the transition layer consisted mainly of intermetallic compounds and metal oxides. The compounds were identified as Al-rich phases, such as Mg{sub 17}Al{sub 12}, Mg{sub 2}Al{sub 3}, FeAl and Fe{sub 4}Al{sub 13}. More noteworthy was that the thickness of the transition layer was determined by Fe–Al compounds. The presence of FeAl and Fe{sub 4}Al{sub 13} was a result of themore » complex processes that were associated with the interfacial reaction of solid steel and liquid Mg–Al alloy. - Highlights: • A technology of laser penetration brazed Mg alloy and steel has been developed. • The interface of Mg/Fe dissimilar joints was investigated using electron microscopy. • The transition layer consisted of intermetallic compounds and metal oxides. • Moreover, the thickness of transition layer was determined by Fe/Al compounds. • The presence of FeAl and Fe{sub 4}Al{sub 13} was associated with the interfacial reaction.« less

Trace elements record complex histories in diogenites

NASA Astrophysics Data System (ADS)

Balta, J. B.; Beck, A. W.; McSween, H. Y.

2012-12-01

Diogenite meteorites are cumulate rocks composed mostly of orthopyroxene and chemically linked to eucrites (basaltic) and howardites (brecciated mixtures of diogenites and eucrites). Together, they represent the largest single family of achondrite meteorites delivered to Earth, and have been spectrally linked to the asteroid 4 Vesta, the largest remaining basaltic protoplanet. However, this spectral link is non-unique as many basaltic asteroids likely formed and were destroyed in the early solar system. Recent work suggested that Vesta may be an unlikely parent body for the diogenites based on correlations between trace elements and short-lived isotope decay products, which would be unlikely to survive on a body as large as Vesta due to its long cooling history [1]. Recent analyses of terrestrial and martian olivines have demonstrated that trace element spatial distributions can preserve evidence of their crystallization history even when major elements have been homogenized [2]. We have mapped minor elements including Cr, Al, and Ti in seemingly homogeneous diogenite orthopyroxenes and found a variety of previously unobserved textures. The pyroxenes in one sample (GRA 98108) are seemingly large grains of variable shapes and sizes, but the trace elements reveal internal grain boundaries between roughly-equal sized original subgrains, with equilibrated metamorphic triple junctions between them and trace element depletions at the boundaries. These trends suggest extraction of trace elements by a magma along those relict grain boundaries during a reheating event. Two other samples show evidence of fracturing and annealing, with trace element mobility within grains. One sample appears to have remained a closed system during annealing (MET 01084), while the other has interacted with a fluid or magma to move elements along annealed cracks (LEW 88679). These relict features establish that the history of diogenite pyroxenes is more complex than their homogeneous major element compositions imply. Many trace element analyses are performed using either bulk rock techniques or spot analyses, and these maps suggest those types of analyses likely sample variable trace element abundances even within otherwise homogeneous grains, rendering their results difficult to interpret. Consequently, the correlation discussed previously between trace elements and short lived isotopes has likely been impacted by post-magmatic alteration and cannot solely be used to argue that HED's cannot be derived from Vesta. Furthermore, these maps strengthen the HED-Vesta link by suggesting that the diogenites underwent an extended history of cooling, reheating, partial melting, impact fragmentation, fluid/melt migration, and finally re-annealing. These complicated steps are particularly noteworthy as the pyroxene cumulate layer on the asteroid Vesta should lie beneath the eucritic crust, implying that early impacts were able to penetrate that crust and affect the diogenite layers early in Vesta's history, most likely while the asteroid was still hot enough to allow for annealing and regrowth of fractured grains. [1] Schiller et al. (2011) [2] Milman-Barris et al. (2008)

A review of lignite resources of western Tennessee and the Jackson Purchase area, western Kentucky

USGS Publications Warehouse

Hackley, Paul C.; Warwick, Peter D.; Thomas, Roger E.; Nichols, Douglas J.; Warwick, Peter D.; Karlsen, Alexander K.; Merrill, Matthew D.; Valentine, Brett J.

2011-01-01

This review of the lignite deposits of western Tennessee and the Jackson Purchase area in western Kentucky (Figure 1) is an updated report on part of the U.S. Geological Survey's National Coal Resource Assessment of the Gulf Coastal Plain Coal Province (see Ruppert et al., 2002; Hackley et al., 2006; Dennen, 2009; and other chapters of this publication). Lignite deposits of western Kentucky and Tennessee are an extension of the Gulf Coastal Plain Coal Province (Cushing et al., 1964), and currently are not economic to mine. These deposits have not been extensively investigated or developed as an energy resource. This review includes a description of the geology of the lignite-bearing units, a discussion of the available coal quality data, and information on organic petrology. Palynological data for lignite samples collected in Kentucky and Tennessee as part of this work are presented in Table 1. Lignite trace element data originally presented in Hackley et al. (2006) are not included in this report due to potential laboratory quality control issues during the time the samples were analyzed (U.S. Geological Survey Energy Resources Program, 2010).

Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

NASA Astrophysics Data System (ADS)

Darwish, Ahmed A.; Fadlallah, Mohamed M.; Badawi, Ashraf; Maarouf, Ahmed A.

2016-07-01

Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-doped boron nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

Prompt Gamma Activation Analysis (PGAA): Technique of choice for nondestructive bulk analysis of returned comet samples

NASA Technical Reports Server (NTRS)

Lindstrom, David J.; Lindstrom, Richard M.

1989-01-01

Prompt gamma activation analysis (PGAA) is a well-developed analytical technique. The technique involves irradiation of samples in an external neutron beam from a nuclear reactor, with simultaneous counting of gamma rays produced in the sample by neutron capture. Capture of neutrons leads to excited nuclei which decay immediately with the emission of energetic gamma rays to the ground state. PGAA has several advantages over other techniques for the analysis of cometary materials: (1) It is nondestructive; (2) It can be used to determine abundances of a wide variety of elements, including most major and minor elements (Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, Co, Ni), volatiles (H, C, N, F, Cl, S), and some trace elements (those with high neutron capture cross sections, including B, Cd, Nd, Sm, and Gd); and (3) It is a true bulk analysis technique. Recent developments should improve the technique's sensitivity and accuracy considerably.

Trace Elements and Health

ERIC Educational Resources Information Center

Pettyjohn, Wayne A.

1972-01-01

Summarizes the effects of arsenic, lead, zinc, mercury, and cadmium on human health, indicates the sources of the elements in water, and considers the possibility of students in high schools analyzing water for trace amounts of the elements. (AL)

Rare Earth Element Yttrium Modified Mg-Al-Zn Alloy: Microstructure, Degradation Properties and Hardness

PubMed Central

Liu, Long; Yuan, Fulai; Zhao, Mingchun; Gao, Chengde; Feng, Pei; Yang, Youwen; Yang, Sheng; Shuai, Cijun

2017-01-01

The overly-fast degradation rates of magnesium-based alloys in the biological environment have limited their applications as biodegradable bone implants. In this study, rare earth element yttrium (Y) was introduced into AZ61 magnesium alloy (Mg-6Al-1Zn wt %) to control the degradation rate by laser rapid melting. The results showed that the degradation rate of AZ61 magnesium alloy was slowed down by adding Y. This was attributed to the reduction of Mg17Al12 phase and the formation of Al2Y phase that has a more active potential, which decreased galvanic corrosion resulting from its coupling with the anodic matrix phase. Meanwhile, the hardness increased as Y contents increased due to the uniform distribution of the Al2Y and Mg17Al12 phases. However, as the Y contents increased further, the formation of excessive Al2Y phase resulted in the increasing of degradation rate and the decreasing of hardness due to its agglomeration. PMID:28772837

Phosphorus application reduces aluminum toxicity in two Eucalyptus clones by increasing its accumulation in roots and decreasing its content in leaves.

PubMed

Teng, Weichao; Kang, Yachao; Hou, Wenjuan; Hu, Houzhen; Luo, Wenji; Wei, Jie; Wang, Linghui; Zhang, Boyu

2018-01-01

Under acidic conditions, aluminum (Al) toxicity is an important factor limiting plant productivity; however, the application of phosphorus (P) might alleviate the toxic effects of Al. In this study, seedlings of two vegetatively propagated Eucalyptus clones, E. grandis × E. urophylla 'G9' and E. grandis × E. urophylla 'DH32-29'were subjected to six treatments (two levels of Al stress and three levels of P). Under excessive Al stress, root Al content was higher, whereas shoot and leaf Al contents were lower with P application than those without P application. Further, Al accumulation was higher in the roots, but lower in the shoots and leaves of G9 than in those of DH32-29. The secretion of organic acids was higher under Al stress than under no Al stress. Further, under Al stress, the roots of G9 secreted more organic acids than those of DH32-29. With an increase in P supply, Al-induced secretion of organic acids from roots decreased. Under Al stress, some enzymes, including PEPC, CS, and IDH, played important roles in organic acid biosynthesis and degradation. Thus, our results indicate that P can reduce Al toxicity via the fixation of elemental Al in roots and restriction of its transport to stems and leaves, although P application cannot promote the secretion of organic acid anions. Further, the higher Al-resistance of G9 might be attributed to the higher Al accumulation in and organic acid anion secretion from roots and the lower levels of Al in leaves.

Finite Element Simulation and Assessment of Single-Degree-of-Freedom Prediction Methodology for Insulated Concrete Sandwich Panels Subjected to Blast Loads

DTIC Science & Technology

2011-02-01

24 Figure 21. Stress-Strain Curve of Expanded Polystyrene Insulation Foam Samples ....................25 Figure 22. Stress-Strain Curve of...Polyisocyanruate Insulation Foam Samples ............................25 Figure 23. Stress-Strain Curve of Extruded Expanded Polystyrene Insulation Foam...for modeling (Naito et al. 2009a). Insulating foams included expanded polystyrene (EPS), extruded expanded polystyrene (XPS), and polyisocyanurate

Changes in macrominerals, trace elements and pigments content during lettuce (Lactuca sativa L.) growth: influence of soil composition.

PubMed

Pinto, Edgar; Almeida, Agostinho A; Aguiar, Ana A R M; Ferreira, Isabel M P L V O

2014-01-01

Changes in macrominerals, trace elements and photosynthetic pigments were monitored at 5 stages of lettuce growth. Plants were grown in three experimental agriculture greenhouse fields (A1, A2 and A3). Soil composition was also monitored to understand its influence on lettuce composition. In general, the content of macrominerals, trace elements, chlorophylls and carotenoids decreased during lettuce growth and consequently, high nutritional value was observed at younger stages. A2 lettuces showed an increase of Fe, Al, Cr, V and Pb due to the different soil physicochemical parameters. Multiple linear regression analysis with stepwise variable selection, indicated that soil characteristics, namely, pH(CaCl2) for Fe and Cr, silt and fine-sand for Al and V, OM for Al and Pb, coarse-sand and CEC for Cr, had a key role determining element bioavailability and plant mineral content. Thus, lettuce nutritional value was strongly dependent of growth stage and soil characteristics. Copyright © 2013 Elsevier Ltd. All rights reserved.

Composition of the lithospheric mantle in the northern part of Siberian craton: Constraints from peridotites in the Obnazhennaya kimberlite

NASA Astrophysics Data System (ADS)

Sun, Jing; Liu, Chuan-Zhou; Kostrovisky, Sergey I.; Wu, Fu-Yuan; Yang, Jin-Hui; Chu, Zhu-Yin; Yang, Yue-Heng; Kalashnikova, Tatiana; Fan, Sheng

2017-12-01

The character of the lithospheric mantle of the northern Siberian craton is not well established; nearly all published data are for mantle xenoliths from a single kimberlite in the center of the craton (Udachnaya). We report major elements of the whole rock, trace elements data of clinopyroxene and Re-Os isotope and PGE concentration of mantle xenoliths from the Obnazhennaya kimberlite pipe (160 Ma) in the northern part of Siberian craton. The Obnazhennaya mantle xenoliths include spinel harzburgites, spinel dunites, spinel lherzolites and spinel-garnet lherzolite. The spinel harzburgites and dunites have refractory compositions, with 0.23-1.35 wt% Al2O3, 0.41-3.11 wt% CaO and 0.00-0.09 wt% TiO2, whereas the lherzolites (both spinel- and spinel-garnet-) have more fertile compositions, containing 2.16-6.55 wt% Al2O3, 2.91-7.55 wt% CaO and 0.04-0.15 wt% TiO2. The trace element compositions and mineralogical textures of the Obnazhennaya xenoliths indicate the occurrence of metasomatic enrichments, including carbonatite melts, basaltic melts from Siberian Trap and kimberlitic melts. The spinel harzburgites and dunites have 187Os/188Os of 0.11227-0.11637, giving a TRD age of 1.6-2.2 Ga. This suggests that old cratonic mantle still existed beneath the Obnazhennaya. In contrast, both spinel and spinel-garnet lherzolites have more radiogenic 187Os/188Os ratios (0.11931-0.17627), enriched P-PGEs. But the higher Al2O3 and Os character of these lherzolites suggest that they were not juvenile mantle but the refertilized ancient mantle. Therefore, our results suggest that the cratonic mantle beneath the northern part of Siberian craton contain both ancient and reworked lithospheric mantle, and the metasomatism may not be effective at overprinting/eroding the pre-existing lithosphere.

Planetary Protection Considerations in EVA System Design

NASA Technical Reports Server (NTRS)

Eppler, Dean B.; Kosmo, Joseph J.

2011-01-01

To better constrain their origin, we have performed systematic studies of the siderophile element distribution in metal from Enstatite achondrites and iron-rich meteorites linked to Enstatite achondrites. Humayun (2010) reported 20 siderophile elements in the metal of Horse Creek, Mt. Egerton and Tucson, three iron meteorites known for their high Si content in their metal. The Horse Creek and Mt. Egerton irons have elemental patterns identical to metallic solids derived from partially molten enstatite chondrites. Tucson has an unusual siderophile element pattern that is reminiscent of IVA irons, except for the most volatile siderophiles with condensation temperatures below that of Cu (Sb, Ge, Sn) which are more depleted. The origin of Tucson metal is likely linked to an impact involving a reduced chondritic body that provided the silicates, and IVA iron. In a related study, van Acken et al. (2010) reported siderophile element abundances in metal and sulfides from aubrites, chondritic inclusions in aubrites, and other enstatite achondrites (including a separate section of Mt. Egerton). They found that aubrite metal was linked to metal in enstatite chondrites by low degree partial melting forming sulfur-rich metallic liquids. A restite origin of aubrites is not consistent with these metal compositions. The link between the metal compositions and cumulate silicates is not simple. The metal must have been incorporated from enstatite chondritic material that was assimilated by the aubrite magma. A manuscript is in preparation (van Acken et al., 2010). In a related study, van Acken et al. (2010, submitted) reported new precise Os isotope ratios and highly siderophile element abundances in Enstatite chondrites, Enstatite achondrites, Rumurutite chondrites to explore the range of nucleosynthetic variation in s-process Os. They observed nucleosynthetic anomalies, deficiencies of s-process Os, in most primitive enstatite chondrites, but showed the Rumurutite chondrites have very little expression of these anomalies. hardware from the human-occupied area may limit (although not likely eliminate) external materials in the human habitat. Definition of design-to requirements is critical to understanding technical feasibility and costs. The definition of Planetary Protection needs in relation to EVA mission and system element development cost impacts should be considered and interpreted in terms of Plausible Protection criteria. Since EVA operations will have the most direct physical interaction with the Martian surface, PP needs should be considered in the terms of mitigating hardware and operations impacts and costs.

Cross Sections of P-Induced Reactions up to 100 MeV for the Interpretation of Solar Cosmic Ray Produced Nuclides

NASA Astrophysics Data System (ADS)

Schiekel, T.; Rosel, R.; Herpers, U.; Bodemann, R.; Michel, R.; Dittrich, B.; Hofmann, H. J.; Suter, M.; Wolfli, W.; Holmqvist, B.; Conde, H.; Malmborg, P.

1992-07-01

Integral excitation functions for the production of residual nuclides by proton-induced reactions are the basic data for an accurate modelling of the interactions of solar cosmic ray (SCR) particles with extraterrestrial matter. Due to the relatively low energies (<200 MeV/A) of SCR particles the production of nuclear active secondary particles can be widely neglected and theoretical production rate depth profiles can be calculated by simply folding the depth dependent SCR spectra with thin target cross sections of the underlying nuclear reactions. The accuracy of such calculations exclusively depends on the quality of the available cross sections. For many nuclides, in particular for long-lived radionuclides and stable rare gas isotopes, the exis- ting cross section database is neither comprehensive nor reliable. Therefore, we started a series of experiments to improve this situation. Eighteen elements (C, N as Si3N4, O as SiO2, Mg, Al, Si, Ti, V, Mn as Mn/Ni-alloy, Fe, Co, Ni, Cu, Zr, Nb, Rh, Ba as Ba-contai- ning glass, and Au) were irradiated with 94 and 99 MeV protons at the external beam of the TSL-cyclotron at Uppsala. Cross sections were determined using the stacked foil technique. Beam monitoring was done by investigating the production of ^22Na from Al, for which evaluated cross sections exist. Residual nuclides were measured by X-, gamma- and accelerator-mass spectrometry. In order to check the quality of our experimental procedure some target elements (22 <= Z <= 28) were included in the new exper- iments, which had been formerly irradiated at Julich, at Louvain La Neuve, and at IPN Orsay. Comparisons between the earlier measurements (1,2) and the new cross sections showed excellent agreement. Up to now, cross sections were measured for more than 120 different reactions. Here, we report on the results obtained for the target elements C, N, O, Mg, Al, and Si. The status of experimental excitation functions for the production of some radionuclides relevant for SCR interactions with terrestrial and extraterrestrial matter, i.e., ^7Be and ^10Be from C, N, O, Mg, Al, and Si and ^22Na and ^26Al from Mg, Al, and Si, is discussed in detail. In order to investigate whether theoretical calculations can be used to supply the necessary cross sections for SCR model calcu- lations, a theoretical analysis of the experimental data is given on the basis of model calculations of equilibrium and pre-equilibrium reactions for light target elements. The new data are applied to model calculations of the production of SCR-produced nuclides in lunar surface materials and in meteorites. Acknowledgement: This work was supported by the Deutsche Forschungsgemeinschaft and by the Swiss National Science Foundation. References: (1) Michel et al. (1984) J. Geophys Res. 89, B673- B684. (2) Michel R. et al. (1985) Nucl. Phys. A441, 617-639.

Reconciling elemental Ba and barite as proxies of export production: Multiple Ba reservoirs in biogenic sediment

NASA Astrophysics Data System (ADS)

Murray, R. W.; Kryc, K. A.; Murray, D. W.

2003-12-01

The use of barite has long been recognized as a promising proxy for export production due to the relationship between its formation and settling biogenic matter. Accordingly, excess Ba (total Ba minus Ba associated with terrigenous material) calculations have been applied as a proxy of barite to assess export production, although this approach may be problematic. For example, because there are additional carrying phases of Ba in sediment other than terrigenous Ba and barite (e.g., oxides, organic matter), excess Ba may not be related in a predictable manner to export production. Indeed, previous workers have also identified the importance of non-barite reservoirs of Ba in sediment traps (e.g., Dymond et al., 1992; Francois et al., 1995) and sediment (e.g., Schroeder et al., 1997; Eagle et al., 2003). Despite these multiple reservoirs, the use of elemental Ba in biogenic sediment as a proxy of export production has a proven and resilient track record. To further understand the partitioning of Ba in biogenic sediment, we sequentially extracted seven, operationally-defined fractions (loosely-bound, exchangeable, carbonate, oxide, organic, opal, and residual) of sediment from surface and downcore samples from a cross-equatorial meridional transect in the equatorial Pacific. We find that Ba is evenly distributed between the sedimentary components with approximately 25-40 percent of the total extracted Ba in each of the exchangeable, carbonate, and oxide fractions for both surface and downcore sediment samples. In the surface sediment transect across the equator, there is no Ba in the residual fraction, and between 10 and 50 percent of the total extracted Ba is in the organic fraction. Also, downcore samples that were extracted from sediments with low relative bulk Ba/Ti tend to have Ba in both the residual and organic fractions as opposed to samples with high relative bulk Ba/Ti where there is a lack of Ba in both the residual and organic fractions. These observations indicate that alternate carriers of Ba, including the exchangeable, carbonate, and oxide fractions of sediment, may exert a larger influence on total Ba than previously suspected. Our new results, when interpreted in the context of recent experimental (Ganeshram et al., 2003) and observational (Eagle et al., 2003) studies of barite formation and the relationship between barite and Ba, further explain why elemental Ba is a valid proxy of export production, as is the distribution of barite (e.g., Paytan et al., 1996). Our results show that while there is a reorganization of elemental Ba between sedimentary phases (which can be considered a continuation of the water column processes described by Ganeshram et al., 2003), the reorganization only affects the distribution of the Ba and does not destroy the primary relationship between export flux and the accumulation of Ba preserved in the sedimentary record.

RRh2Al10 (R = Ce, Yb): New intermetallic compounds in the 1 : 2 : 10 stoichiometry series

NASA Astrophysics Data System (ADS)

Strydom, A. M.; Djoumessi, R. F.; Blinova, M.; Tursina, A.; Nesterenko, S.; Avzuragova, V.

2018-05-01

The orthorhombic, space group Cmcm YbFe2Al10 structure type series of compounds are known to form with practically the entire series of rare-earth elements R, but only with the three d - electron elements Fe, Ru, and Os. The Ce-derivatives in particular have been of much interest since the first reports of their highly unusual physical properties. Classified as Kondo insulators, CeRu2Al10 and CeOs2Al10 controversially order magnetically and with uncharacteristically high Néel temperatures of ≃ 28 K. CeFe2Al10 on the other hand shows pronounced semiconducting and Kondo features but remains paramagnetic. As part of our ongoing studies into the rich physics of this class of materials we have succeeded in synthesizing new members of the 1:2:10 stoichiometry involving the chemical element Rh for the first time. CeRh2Al10 is found to crystallize in the tetragonal system with space group I41 / amd . Yb Rh2Al10 on the other hand forms in the serial Cmcm orthorhombic structure type. We discuss important similarities between the two types. At 5.310 Å the shortest Ce-Ce distance is, likewise to the situation in CeRu2Al10 and CeOs2Al10 , also well above the Hill limit of 3.40 Å. Despite the cage-like structure and large rare-earth separation distances, this study reveals the onset of long-range magnetic ordering in CeRh2Al10 at 3.9 K. The magnetic ordering develops out of an incoherent Kondo state that dominates the electrical resistivity below about 40 K.

Identifying Type Ia Supernova Mechanisms in Dwarf Spheroidal Galaxies through Analysis of Iron-peak Elemental Abundances

NASA Astrophysics Data System (ADS)

Guo, Rachel; Xie, Justin Long; Kirby, Evan N.

2017-01-01

Through the fusion of nucleons to produce elements heavier than hydrogen and helium, stellar nucleosynthesis produces most of the elements in the universe. Such is the case in a supernova explosion, which creates most of the elements on the periodic table—including iron-peak elements, atomic numbers 21 through 30—through nucleosynthesis and ejects them into the interstellar medium. In this study, we determine the best theoretical supernova model appropriate for the stars in the dwarf spheroidal galaxies Sculptor, Fornax, Ursa Minor, and Leo II by calculating the abundances of iron-peak elements in these stars. To determine iron-peak elemental abundances, we compare synthesized spectra with observed spectra from medium-resolution spectroscopy and determine the best-fitting spectrum by way of a chi-squared minimization. Through inspecting the relationship between the iron-peak element abundances and the abundance of iron itself and by comparing them to previously hypothesized supernova model theories, we discover that the near-Chandrasekhar mass “n1” model, as predicted by Seitenzahl et al., most accurately represents the trends and patterns within our data, presenting new insight into Type Ia supernovae mechanisms within the Milky Way and beyond.

New methods for image collection and analysis in scanning Auger microscopy

NASA Technical Reports Server (NTRS)

Browning, R.

1985-01-01

While scanning Auger micrographs are used extensively for illustrating the stoichiometry of complex surfaces and for indicating areas of interest for fine point Auger spectroscopy, there are many problems in the quantification and analysis of Auger images. These problems include multiple contrast mechanisms and the lack of meaningful relationships with other Auger data. Collection of multielemental Auger images allows some new approaches to image analysis and presentation. Information about the distribution and quantity of elemental combinations at a surface are retrievable, and particular combinations of elements can be imaged, such as alloy phases. Results from the precipitate hardened alloy Al-2124 illustrate multispectral Auger imaging.

Highly siderophile element constraints on the genesis of Azorean lavas

NASA Astrophysics Data System (ADS)

Waters, C. L.; Watanabe, S.; Olson, K. M.; Walker, R. J.; Widom, E.; Hanan, B. B.; Day, J. M.

2013-12-01

Ocean island basalts (OIB) from the Azores archipelago show incompatible element and Sr-Nd-Hf-Pb isotopic heterogeneity both among different islands and within individual islands. This heterogeneity has commonly been attributed to the presence of a mantle plume delivering diverse recycled materials--including terrigenous sediments, metasomatized subcontinental lithosphere, and oceanic crust--to the melting region beneath the Azores (Turner et al., 1997; Widom and Shirey, 1996; Beier et al., 2007). Despite an abundance of datasets including major and trace element and Sr, Nd, Hf, and Pb isotopic compositions, the origin of elemental and isotopic heterogeneity in the Azores remains vigorously debated. We report new highly siderophile element (HSE: Os, Ir, Pd, Pt, Ru, Re) abundance data alongside major and trace element abundance and Nd-Hf-Os-Pb isotope data for a suite of high MgO (8-17 wt%) lavas from the islands of Sao Miguel, Pico, Faial, and Terceira. These lavas span most of the range of incompatible trace element and Nd-Hf-Pb isotopic heterogeneity observed for the Azores. Because HSEs are largely controlled by sulfide, they provide an alternative to the classic perspective of OIB petrogenesis derived from lithophile elements. The results show distinct fractionation patterns for HSEs from different islands at a similar range of MgO contents. Lavas from Pico and Faial have lower absolute HSE abundances (total HSE abundances ~0.001 × CI chondrite; Ir=0.014-0.133 ppb) and are generally more homogeneous than lavas from Terceira and Sao Miguel (total HSE = ~0.003 × CI chondrite; Ir=0.038-0.657 ppb)). Faial and Pico lavas (IrN* = 0.8×0.3, where IrN* = IrN/[(OsN+RuN)0.5] x 100) also commonly lack the positive relative enrichment in Ir observed in Terceira and Sao Miguel lavas (IrN* = 2.4 ×1.1). In contrast to previous studies of OIB in which HSEs are observed to positively correlate with MgO (e.g., Day, 2013), only Re correlates with MgO, as expected given its moderate incompatibility in silicate systems. All other HSEs show wide variability at similar MgO, broadly correlate with each other, yet do not correlate with Nd-Hf-Pb isotope compositions. Thus, we interpret HSE variability to reflect variations in mantle sulfide source composition and sulfide melting beneath different islands in the Azores hotspot.

A volatile-rich Earth's core inferred from melting temperature of core materials

NASA Astrophysics Data System (ADS)

Morard, G.; Andrault, D.; Antonangeli, D.; Nakajima, Y.; Auzende, A. L.; Boulard, E.; Clark, A. N.; Lord, O. T.; Cervera, S.; Siebert, J.; Garbarino, G.; Svitlyk, V.; Mezouar, M.

2016-12-01

Planetary cores are mainly constituted of iron and nickel, alloyed with lighter elements (Si, O, C, S or H). Understanding how these elements affect the physical and chemical properties of solid and liquid iron provides stringent constraints on the composition of the Earth's core. In particular, melting curves of iron alloys are key parameter to establish the temperature profile in the Earth's core, and to asses the potential occurrence of partial melting at the Core-Mantle Boundary. Core formation models based on metal-silicate equilibration suggest that Si and O are the major light element components1-4, while the abundance of other elements such as S, C and H is constrained by arguments based on their volatility during planetary accretion5,6. Each compositional model implies a specific thermal state for the core, due to the different effect that light elements have on the melting behaviour of Fe. We recently measured melting temperatures in Fe-C and Fe-O systems at high pressures, which complete the data sets available both for pure Fe7 and other binary alloys8. Compositional models with an O- and Si-rich outer core are suggested to be compatible with seismological constraints on density and sound velocity9. However, their crystallization temperatures of 3650-4050 K at the CMB pressure of 136 GPa are very close to, if not higher than the melting temperature of the silicate mantle and yet mantle melting above the CMB is not a ubiquitous feature. This observation requires significant amounts of volatile elements (S, C or H) in the outer core to further reduce the crystallisation temperature of the core alloy below that of the lower mantle. References 1. Wood, B. J., et al Nature 441, 825-833 (2006). 2. Siebert, J., et al Science 339, 1194-7 (2013). 3. Corgne, A., et al Earth Planet. Sc. Lett. 288, 108-114 (2009). 4. Fischer, R. a. et al. Geochim. Cosmochim. Acta 167, 177-194 (2015). 5. Dreibus, G. & Palme, H. Geochim. Cosmochim. Acta 60, 1125-1130 (1995). 6. McDonough, W. F. Treatise in Geochemistry 2, 547-568 (2003). 7. Anzellini, S., et al Science 340, 464-6 (2013). 8. Morard, G. et al. Phys. Chem. Miner. 38, 767-776 (2011). 9. Badro, J., et al Proc. Natl. Acad. Sci. U. S. A. 111, 7542-5 (2014).

Influence of pH and temperature on alunite dissolution rates and products

NASA Astrophysics Data System (ADS)

Acero, Patricia; Hudson-Edwards, Karen

2015-04-01

Aluminium is one of the main elements in most mining-affected environments, where it may influence the mobility of other elements and play a key role on pH buffering. Moreover, high concentrations of Al can have severe effects on ecosystems and humans; Al intake, for example, has been implicated in neurological pathologies (e.g., Alzheimer's disease; Flaten, 2001). The behaviour of Al in mining-affected environments is commonly determined, at least partially, by the dissolution of Al sulphate minerals and particularly by the dissolution of alunite (KAl3(SO4)2(OH)6), which is one of the most important and ubiquitous Al sulphates in mining-affected environments (Nordstrom, 2011). The presence of alunite has been described in other acid sulphate environments, including some soils (Prietzel & Hirsch, 1998) and on the surface of Mars (Swayze et al., 2008). Despite the important role of alunite, its dissolution rates and products, and their controlling factors under conditions similar to those found in these environments, remain largely unknown. In this work, batch dissolution experiments have been carried out in order to shed light on the rates, products and controlling factors of alunite dissolution under different pH conditions (between 3 and 8) and temperatures (between 279 and 313K) similar to those encountered in natural systems. The obtained initial dissolution rates using synthetic alunite, based on the evolution of K concentrations, are between 10-9.7 and 10-10.9 mol-m-2-s-1, with the lowest rates obtained at around pH 4.8, and increases in the rates recorded with both increases and decreases in pH. Increases of temperature in the studied range also cause increases in the dissolution rates. The dissolution of alunite dissolution is incongruent, as has been reported for jarosite (isostructural with alunite) by Welch et al. (2008). Compared with the stoichiometric ratio in the bulk alunite (Al/K=3), K tends to be released to the solution preferentially over Al, leading to dissolved Al/K ratios between 0.5 and 2.5. This depletion of Al in the solution is especially clear for the experiments at pH 4.5-4.8 and 8 and it is consistent with the results of elemental quantifications of the same proportions in the reacted alunite surfaces using X-ray Photoelectron Spectroscopy (XPS). REFERENCES Flaten, T.P. (2001): Aluminium as a risk factor in Alzheimzer's disease, with emphasis on drinking water. Brain Research Bulletin 55: 187-196. Nordstrom, D.K. (2011): Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters. Applied Geochemistry 26: 1777-1791. Prietzel, J., & Hirsch, C. (1998). Extractability and dissolution kinetics of pure and soil-added synthesized aluminium hydroxy sulphate minerals. European journal of soil science, 49(4), 669-681. Swayze, G.A., Ehlmann, B.L., Milliken, R.E., Poulet, F., Wray, J.J., Rye, R.O., Clark, R.N., Desborough, G.A., Crowley, J.K., Gondet, B., Mustard, J.F., Seelos, K.D. and Murchie, S.L., 2008. Discovery of the Acid-Sulfate Mineral Alunite in Terra Sirenum, Mars, Using MRO CRISM: Possible Evidence for Acid-Saline Lacustrine Deposits?, American Geophysical Union, Fall Meeting 2008, abstract #P44A-04. Welch, S. A., Kirste, D., Christy, A. G., Beavis, F. R., & Beavis, S. G. (2008): Jarosite dissolution II'Reaction kinetics, stoichiometry and acid flux. Chemical Geology, 254(1), 73-86.

Application of Cathodoluminescence to The Study of Feldspars: Imaging and Spectrometry

NASA Astrophysics Data System (ADS)

Fonseca, Rute; Couto, Helena

2017-12-01

Cathodoluminescence (CL) studies were carried out on polished thin sections of different feldspar samples (from migmatites, granites, aplite-pegmatites and granitic aggregates) using a hot cathode CL equipment HC3-LM coupled to an optical microscope and to a spectrometer (SpectraPro 2300i and a CCD Pixis 400B detector and the software Winspec32) from the Faculty of Sciences of University of Porto. The system was operated at 14kV and a filament current of 0.18 mA. The samples were coated with a thin gold film using a Cressington 108 Auto device. Luminescence images were acquired during the CL analysis with an adapted digital video-camera (KAPPA PS 40C-285 (DX) with dual stage Peltier cooling) and an acquisition time between 351ms and 3,52s. The CL study, including imaging and spectrometry, proved to be an important tool to complement the feldspar petrography as it contributes to the identification of features not observed under optical microscope. The application of the Cathodoluminescence to feldspar allows distinguishing between potassic feldspar and plagioclase, differentiating generations of feldspar and displaying internal zoning and growth areas, among other. The spectrometry complements the CL imaging. It allows obtaining a qualitative level of emission intensity, which permits the interpretation of the nature of this luminescence in each feldspar. Bands shown in the spectra are related to the existing activator elements. In the present study, it was found an association of each feldspar to different spectra and respective colour. The plagioclases exhibit yellow or green luminescence. The activator element is Mn2+, showing a broad emission band between 550 - 570 nm specially detected on this type of feldspars, due to the replacement of K+ for Mn2+. The potassium feldspars have more or less intense blue colour associated with various activators elements: the activator element is Cu2+ showing a broad emission band between 420±5 nm. This emission band can be detected either in potassium feldspar or in plagioclases, but when associated with the blue colour, it indicates that it is a potassium feldspar. Spectra with a wavelength of 460±10 nm, associated to the element activator/synthesizer Ti3+, which is initially deposited as Ti4+, replacing Al, as temperature rise. The emission band with a wavelength of 860 nm correspond to the activator element Pb+, and occurs specially in potassium feldspar like adularia and orthoclase. The activator element Al - O - Al, show a broad emission band between 450-480 nm. This emission in CL is caused by the replacement of Al3+ and Si4+ in feldspars.

Evidence of Arc Magma Genesis in a Paleo-Mantle Wedge, the Higashi-Akaishi Peridotite, Japan

NASA Astrophysics Data System (ADS)

Till, C. B.; Guild, M. R.; Grove, T. L.; Carlson, R. W.

2014-12-01

Located in the Sanbagawa subduction-related high-pressure metamorphic belt in SW Japan on the island of Shikoku, the Higashi-akaishi peridotite body is composed of dunite, lherzolite and garnet clinopyroxenite, interfingered in one locality with quartz-rich eclogite. Previous work indicates the P-T history of the peridotite includes rapid prograde metamorphism with peak temperatures of 700-810°C and pressures of 2.9-3.8 GPa [1] at ~88-89 Ma followed by rapid exhumation at >2.5 cm/yr [2,3]. Major and trace element and isotopic data from samples within the Higashi-akaishi peridotite presented here and in another recent study [4] provide a record of subduction zone melting processes in a paleo-mantle wedge. Ultramafic samples range from 40-52 wt.% SiO2, 1-11 wt.% Al2O3 and 21-45 wt.% MgO with olivine and clinopyroxene Mg#'s as high as 0.93. The quartz-rich eclogite contains 62 wt.% SiO2, 6 wt.% MgO and 13 wt.% Al2O3 with trace element concentrations that are enriched relative to the ultramafic samples. 87Sr/86Sr (.703237-.704288), 143Nd/144Nd (ɛNd=+2 to +6) and Pb isotopic compositions are within the range of previously studied Japanese arc rocks. We interpret the pyroxenites as shallowly crystallized cumulates with varying amounts of trapped hydrous melt and the harzburgites as residues of melting. The peak P-T conditions of these rocks are similar to the solidus conditions of H2O-saturated fertile mantle near the base of the mantle wedge [5,6]. The presence of garnet porphyroblasts that enclose primary euhedral chlorite together with the chemical evidence, suggest these samples are associated with mantle melting in the presence of H2O. Major element modeling suggests the quartz-rich eclogite composition can be reproduced through mixing melts of subducted sediment with wet peridotite melts in the mantle wedge. Thus the Higashi-aikashi rock suite provides an in-situ record of the beginnings of hydrous melting and the mechanisms of metasomatism in the mantle wedge. [1] Enami et al. (2004) J. Meta. Geol. 22, 1-15. [2] Okamoto et al. (2004) Terra Nova 16, 81-89. [3] Wallis et al. (1990) J. Meta. Geol. 27, 93-105. [4] Hattori et al. (2010) Island Arc 19, 192-207. [5] Grove et al. (2006) Earth Planet. Sci. Lett. 249, 74-89. [6] Till et al. (2012) Cont. Min. Petrol. 163, 669-688.

Microstructure and properties of Ti-Al intermetallic/Al2O3 layers produced on Ti6Al2Mo2Cr titanium alloy by PACVD method

NASA Astrophysics Data System (ADS)

Sitek, R.; Bolek, T.; Mizera, J.

2018-04-01

The paper presents investigation of microstructure and corrosion resistance of the multi-component surface layers built of intermetallic phases of the Ti-Al system and an outer Al2O3 ceramic sub-layer. The layers were produced on a two phase (α + β) Ti6Al2Mo2Cr titanium alloy using the PACVD method with the participation of trimethylaluminum vapors. The layers are characterized by a high surface hardness and good corrosion, better than that of these materials in the starting state. In order to find the correlation between their structure and properties, the layers were subjected to examinations using optical microscopy, X-ray diffraction analysis (XRD), surface analysis by XPS, scanning electron microscopy (SEM), and analyses of the chemical composition (EDS). The properties examined included: the corrosion resistance and the hydrogen absorptiveness. Moreover growth of the Al2O3 ceramic layer and its influence on the residual stress distribution was simulated using finite element method [FEM]. The results showed that the produced layer has amorphous-nano-crystalline structure, improved corrosion resistance and reduces the permeability of hydrogen as compared with the base material of Ti6Al2Mo2Cr -titanium alloy.

Characterization and evolution of dissolved organic matter in acidic forest soil and its impact on the mobility of major and trace elements (case of the Strengbach watershed)

NASA Astrophysics Data System (ADS)

Gangloff, Sophie; Stille, Peter; Pierret, Marie-Claire; Weber, Tiphaine; Chabaux, François

2014-04-01

Dissolved Organic Carbon (DOC) plays an important role in the behavior of major and trace elements in the soil and influences their transfer from soil to soil solution. The first objective of this study is to characterize different organic functional groups for the Water Extractable Organic Carbon (WEOC) fractions of a forest soil as well as their evolution with depth. The second objective is to clarify the influence of these organic functional groups on the migration of the trace elements in WEOC fractions compared to those in the soil solution obtained by lysimeter plates. All experiments have been performed on an acidic forest soil profile (five depths in the first meter) of the experimental spruce parcel in the Stengbach catchment. The Infra-red spectra of the freeze-dried WEOC fractions show a modification of the molecular structure with depth, i.e. a decrease of the polar compounds such as polysaccharides and an increase of the less polar hydro-carbon functional groups with a maximum value of the aromaticity at 30 cm depth. A Hierarchical Ascending Classification (HAC) of the evolution of Water Extractable Chemical Elements (WECE) with the evolution of the organic functional groups in the organic matter (OM) enriched soil compartments permits recognition of relationships between trace element behavior and the organic functional group variations. More specifically, Pb is preferentially bound to the carboxylic acid function of DOC mainly present in the upper soil compartment and rare earth elements (REE) show similar behavior to Fe, V and Cr with a good affinity to carboxy-phenolic and phenolic groups of DOC. The experimental results show that heavy REE compared to light REE are preferentially bound to the aromatic functional group. This different behavior fractionates the REE pattern of soil solutions at 30 cm depth due to the here observed aromaticity enrichment of DOC. These different affinities for the organic functional groups of the DOC explain some aspects of the behavior of trace elements in soil solutions and in the soil profile but, also the competition between trace elements in complexation with DOC. The results of this study are important for the understanding of the mobility and the migration of pollutants (as heavy metals or radionuclides) as well as nutrients in natural ecosystems. WE PrN/YbN is constant between 3 and 16 cm depth whereas SS PrN/YbN slightly decreases from 0.80 at 5 cm depth to 0.74 at 10 cm depth. This results from Pr (LREE) enrichment in the soil solution of the upper soil compartment caused by vegetation controlled LREE recycling and/or atmospheric depositions (see above). WE PrN/YbN and SS PrN/YbN show similar depth dependent distributions including the enrichment at 30 cm depth. It results from Yb depletion at this depth and enrichment in the deeper soil compartment compared to Pr. Similar to Marsac et al. (2012, 2013) one might suggest that there is competition between Fe3+, Al3+ and REE for the binding with DOC. They have a high affinity with the same organic functional groups which is confirmed by the classification scheme (Fig. 8). The studies of Marsac et al. suggest that at acidic pH and low metal/DOC ratios, Fe3+and Al3+ compete more with HREE than LREE; moreover, at high metal/DOC ratios and acidic pH, Al3+ competes with LREE. The Fig. 13 showing the variations of WECEN for Al and Fe in function of WECEN LREE and HREE confirms Marsac et al.’s observations. The slope of the extrapolation line resulting from WECEN Al and HREE values remains rather unchanged for the OM depleted and enriched soil compartments; thus, the change in the metal/DOC ratio in the soil does not change the extraction behavior of Al and HREE. However, the WECEN Fe strongly increase compared to the corresponding HREE values in the OM enriched compartment pointing to the competition between Fe and HREE. Alternatively, one observes that the WECEN Fe and LREE values in the OM enriched compartment plot on the extrapolation line derived from OM depleted soil samples. Thus, in this case, the change in the metal/DOC ratio does not affect the extraction behavior of Fe and LREE. However, the WECEN values for Al and corresponding LREE of samples from the OM enriched soil compartment plot below the extrapolation line and point to the competition between Al and LREE. These results are also in agreement with the REE distribution pattern of the soil solutions from the same site which are at greater depth LREE depleted (Stille et al., 2009).

In situ major and trace element analysis of amphiboles in quartz monzodiorite porphyry from the Tonglvshan Cu-Fe (Au) deposit, Hubei Province, China: insights into magma evolution and related mineralization

NASA Astrophysics Data System (ADS)

Duan, Deng-Fei; Jiang, Shao-Yong

2017-05-01

The Tonglvshan deposit is the largest Cu-Fe (Au) skarn deposit in the Edong district, which is located in the westernmost part of the Middle and Lower Yangtze River metallogenic belt, China. In this study, we performed a detailed in situ analysis of major and trace elements in amphiboles from the ore-related Tonglvshan quartz monzodiorite porphyry using electron microprobe (EMPA) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Two distinct populations of amphiboles, which can be distinguished by their aluminum content, are found in the quartz monzodiorite porphyry. The low-aluminum (Low-Al) amphiboles are subhedral or anhedral and formed at 46.3-73.5 MPa and 713-763 °C. In contrast, the high-aluminum (High-Al) amphiboles are euhedral and formed at 88-165 MPa and 778-854 °C. Some euhedral amphiboles are partially or completely replaced by Low-Al amphibole. The compositions of parental melts in equilibrium with the High-Al amphibole ( Melt 1) and Low-Al amphibole ( Melt 2) were computed by applying solid/liquid partition coefficients. This modeling shows that magma in equilibrium with High-Al amphibole ( Melt 1) underwent 40% fractional crystallization of amphibole, plagioclase and apatite at a depth of 5 km to evolve to magma in equilibrium with Low-Al amphibole ( Melt 2). Copper enrichment occurred in the magma after undergoing fractional crystallization. The magma had a high oxygen fugacity, increasing from NNO + 1 ( Melt 1) through NNO + 2 to HM ( Melt 2), which could have prevented the loss of Cu (and possibly Au) to sulfide minerals during crystallization. Finally, the evolved magma intruded to shallower depths, where it presumably exsolved aqueous ore-forming fluids. Therefore, the large Cu-Fe-Au reserves of the Tonglvshan deposit can likely be attributed to a combination of controlling factors, including high oxygen fugacity, fractional crystallization, fluid exsolution, and a shallow emplacement depth.

Geochemical behaviour of PM10 aerosol constituents under the influence of succeeding anticyclonic/cyclonic situations: case of Sfax City, southern Tunisia.

PubMed

Bahloul, Moez; Chabbi, Iness; Dammak, Rim; Amdouni, Ridha; Medhioub, Khaled; Azri, Chafai

2015-12-01

The present study investigates the geochemical behaviour of PM10 aerosol constituents (Cl, Na, Si, Al, Ca, Fe, Mg, Mn, Pb, Zn, S) at Sfax City (Tunisia) under succeeding meteorological conditions, including short-lived anticyclonic, cyclonic and prolonged anticyclonic situations. The results revealed daily total concentrations fluctuating between 4.07 and 88.51 μg/m(3). The highest level recorded was noted to occur under the effect of the short-lived anticyclonic situation characterized by low wind speeds. It was 1.5 times higher than those recorded during cyclonic and long-lived anticyclonic situations characterized by moderate to high wind speeds. During the cyclonic situation, the marked increase of (Na and Cl) concentrations is associated with relatively high sea wind speeds (6 to 9 m/s), which are in turn responsible for a slight increase of crustal elements such as Al, Ca, Si, Fe and Mg, by the entrainment in the air of dust from roads and undeveloped areas. During the two anticyclonic situations, the simultaneous increase (due to communal transport) of crustal (Ca, Si, Al, Fe, Mg) and man-made (Mn, S, Pb, Zn) elements was noted to be associated with the dominance of terrigenious wind flows with speeds varying between 1.5 and 4 m/s. However, the significant contribution rates observed for Cl under the prevalence of such winds as compared to other crustal elements such as Fe suggested the influence of the sebkhas of Southern Tunisia.

Origin of the Elements

NASA Astrophysics Data System (ADS)

Truran, J. W., Jr.; Heger, A.

2003-12-01

Nucleosynthesis is the study of the nuclear processes responsible for the formation of the elements which constitute the baryonic matter of the Universe. The elements of which the Universe is composed indeed have a quite complicated nucleosynthesis history, which extends from the first three minutes of the Big Bang through to the present. Contemporary nucleosynthesis theory associates the production of certain elements/isotopes or groups of elements with a number of specific astrophysical settings, the most significant of which are: (i) the cosmological Big Bang, (ii) stars, and (iii) supernovae.Cosmological nucleosynthesis studies predict that the conditions characterizing the Big Bang are consistent with the synthesis only of the lightest elements: 1H, 2H, 3He, 4He, and 7Li (Burles et al., 2001; Cyburt et al., 2002). These contributions define the primordial compositions both of galaxies and of the first stars formed therein. Within galaxies, stars and supernovae play the dominant role both in synthesizing the elements from carbon to uranium and in returning heavy-element-enriched matter to the interstellar gas from which new stars are formed. The mass fraction of our solar system (formed ˜4.6 Gyr ago) in the form of heavy elements is ˜1.8%, and stars formed today in our galaxy can be a factor 2 or 3 more enriched (Edvardsson et al., 1993). It is the processes of nucleosynthesis operating in stars and supernovae that we will review in this chapter. We will confine our attention to three broad categories of stellar and supernova site with which specific nucleosynthesis products are understood to be identified: (i) intermediate mass stars, (ii) massive stars and associated type II supernovae, and (iii) type Ia supernovae. The first two of these sites are the straightforward consequence of the evolution of single stars, while type Ia supernovae are understood to result from binary stellar evolution.Stellar nucleosynthesis resulting from the evolution of single stars is a strong function of stellar mass (Woosley et al., 2002). Following phases of hydrogen and helium burning, all stars consist of a carbon-oxygen core. In the mass range of the so-called "intermediate mass" stars (1<˜M/M⊙<˜10), the temperatures realized in their degenerate cores never reach levels at which carbon ignition can occur. Substantial element production occurs in such stars during the asymptotic giant branch (AGB) phase of evolution, accompanied by significant mass loss, and they evolve to white dwarfs of carbon-oxygen (or, less commonly, oxygen-neon) composition. In contrast, the increased pressures that are experienced in the cores of stars of masses M>˜10M⊙ yield higher core temperatures that enable subsequent phases of carbon, neon, oxygen, and silicon burning to proceed. Collapse of an iron core devoid of further nuclear energy then gives rise to a type II supernova and the formation of a neutron star or black hole remnant (Heger et al., 2003). The ejecta of type IIs contain the ashes of nuclear burning of the entire life of the star, but are also modified by the explosion itself. They are the source of most material (by mass) heavier than helium.Observations reveal that binary stellar systems comprise roughly half of all stars in our galaxy. Single star evolution, as noted above, can leave in its wake compact stellar remnants: white dwarfs, neutron stars, and black holes. Indeed, we have evidence for the occurrence of all three types of condensed remnant in binaries. In close binary systems, mass transfer can take place from an evolving companion onto a compact object. This naturally gives rise to a variety of interesting phenomena: classical novae (involving hydrogen thermonuclear runaways in accreted shells on white dwarfs (Gehrz et al., 1998)), X-ray bursts (hydrogen/helium thermonuclear runaways on neutron stars (Strohmayer and Bildsten, 2003)), and X-ray binaries (accretion onto black holes). For some range of conditions, accretion onto carbon-oxygen white dwarfs will permit growth of the CO core to the Chandrasekhar limit MCh=1.4M⊙, and a thermonuclear runaway in to core leads to a type Ia supernova.In this chapter, we will review the characteristics of thermonuclear processing in the three environments we have identified: (i) intermediate-mass stars; (ii) massive stars and type II supernovae; and (iii) type Ia supernovae. This will be followed by a brief discussion of galactic chemical evolution, which illustrates how the contributions from each of these environments are first introduced into the interstellar media of galaxies. Reviews of nucleosynthesis processes include those by Arnett (1995), Trimble (1975), Truran (1984), Wallerstein et al. (1997), and Woosley et al. (2002). An overview of galactic chemical evolution is presented by Tinsley (1980).

Contents of chemical elements in stomach during prenatal development: different age-dependent dynamical changes and their significance

PubMed Central

Hou, Shao-Fan; Li, Hai-Rong; Wang, Li-Zhen; Li, De-Zhu; Yang, Lin-Sheng; Li, Chong-Zheng

2003-01-01

AIM: To observe dynamic of different chemical elements in stomach tissue during fetal development. METHODS: To determine contents of the 21 chemical elements in each stomach samples from fetus aging four to ten months. The content values were compared to those from adult tissue samples, and the values for each month group were also analyzed for dynamic changes. RESULTS: Three representations were found regarding the relationship between contents of the elements and ages of the fetus, including the positive correlative (K), reversely correlative (Na, Ca, P, Al, Cu, Zn, Fe, Mn, Cr, Sr, Li, Cd, Ba, Se) and irrelevant groups (Mg, Co, Ni, V, Pb, Ti). CONCLUSION: The chemical elements’ contents in stomach tissues were found to change dynamically with the stomach weights. The age-dependent representations for different chemical elements during the prenatal development may be of some significance for assessing development of fetal stomach and some chemical elements. The data may be helpful for the nutritional balance of fetus and mothers during prenatal development and even the perinatal stages. PMID:12717857

Inclusion of Regional Poroelastic Material Properties Better Predicts Biomechanical Behavior of Lumbar Discs Subjected to Dynamic Loading

PubMed Central

Williams, Jamie R.; Natarajan, Raghu N.; Andersson, Gunnar B.J.

2009-01-01

Understanding the relationship between repetitive lifting and the breakdown of disc tissue over several years of exposure is difficult to study in vivo and in vitro. The aim of this investigation was to develop a three-dimensional poroelastic finite element model of a lumbar motion segment that reflects the biological properties and behaviors of in vivo disc tissues including swelling pressure due to the proteoglycans and strain dependent permeability and porosity. It was hypothesized that when modeling the annulus, prescribing tissue specific material properties will not be adequate for studying the in vivo loading and unloading behavior of the disc. Rather, regional variations of these properties, which are known to exist within the annulus, must also be included. Finite element predictions were compared to in vivo measurements published by Tyrrell et al., (Tyrrell et al., 1985) of percent change in total stature for two loading protocols, short-term creep loading and standing recovery and short-term cyclic loading with standing recovery. The model in which the regional variations of material properties in the annulus had been included provided an overall better prediction of the in vivo behavior as compared to the model in which the annulus properties were assumed to be homogenous. This model will now be used to study the relationship between repetitive lifting and disc degeneration. PMID:17156786

[Effect of loading suit "Penguin" on human metabolism during movements].

PubMed

Barer, A S; Kozlovskaia, I B; Tikhomirov, E P; Sinigin, V M; Letkova, L I

1998-01-01

Additional energy expenses due to stretching of the elastic elements of anti-loading suit (ALS) "Penguin" as a whole (shoulders-feet) or only its lower part (waist-feet) in the course of cyclic leg movements were measured in five female and five male volunteers. ALS design enabled tensometric monitoring of efforts applied to specific elastic elements, and total efforts applied to the shoulder or pelvic girdles separately. Energy spend were determined with the indirect calorimetric techniques from the data of the expired air analysis. Registered were electromyograms of m. longus spinae, femoral extensor (m. biceps femoris) and femoral flexor (m. rectus femoris), and m. gastrocnemius. On the first stage, bicycle ergometer was pedaled w/o loading with a frequency of 60 cycles/min. The next stage included testing by incremental loading in which pedaling ceased at the pulse rate of 150/min. Results of the experiments that did not require stretching elastic parts of the suit and in which the total strain effort made up 20 to 25 kg and 15 to 16 kg by males and females, respectively, were compared. It was ascertained that ALS enhanced metabolism during motion by 20 to 30%; however, there was no significant difference in energy expenses when loaded by the whole suit or only its lower part.

DART model for irradiation-induced swelling of uranium silicide dispersion fuel elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rest, J.; Hofman, G.L.

1999-04-01

Models for the interaction of uranium silicide dispersion fuels with an aluminum matrix, for the resultant reaction product swelling, and for the calculation of the stress gradient within the fuel particles are described within the context of DART fission-gas-induced swelling models. The effects of an aluminide shell on fuel particle swelling are evaluated. Validation of the model is demonstrated by comparing DART calculations with irradiation data for the swelling of U{sub 3}SiAl-Al and U{sub 3}Si{sub 2}-Al in variously designed dispersion fuel elements.

A Compilation of Metals and Trace Elements Extracted from Materials Relevant to Pharmaceutical Applications such as Packaging Systems and Devices.

PubMed

Jenke, Dennis; Rivera, Christine; Mortensen, Tammy; Amin, Parul; Chacko, Molly; Tran, Thang; Chum, James

2013-01-01

Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions and the levels of 32 metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The extracting solvents included aqueous mixtures at low and high pH and an organic solvent mixture (40/60 ethanol water). The sealed vessel extractions were performed by placing an appropriate portion of the test articles and an appropriate volume of extracting solution in inert extraction vessels and exposing the extraction units (and associated extraction blanks) to defined conditions of temperature and duration. The levels of extracted target elements were measured by inductively coupled plasma atomic emission spectroscopy. The overall reporting threshold for most of the targeted elements was 0.05 μg/mL, which corresponds to 0.5 μg/g for the most commonly utilized extraction stoichiometry (1 g of material per 10 mL of extracting solvent). The targeted elements could be classified into four major groups depending on the frequency with which they were present in the over 250 extractions reported in this study. Thirteen elements (Ag, As, Be, Cd, Co, Ge, Li, Mo, Ni, Sn, Ti, V, and Zr) were not extracted in reportable quantities from any of the test articles under any of the extraction conditions. Eight additional elements (Bi, Cr, Cu, Mn, Pb, Sb, Se, and Sr) were rarely extracted from the test articles at reportable levels, and three other elements (Ba, Fe, and P) were infrequently extracted from the test articles at reportable levels. The remaining eight elements (Al, B, Ca, Mg, Na, S, Si, and Zn) were more frequently present in the extracts in reportable quantities. These general trends in accumulation behavior were compared to compiled lists of elements of concern as impurities in pharmaceutical products. Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions, and the levels of thirty-two metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The targeted elements could be classified into four major groups depending on the frequency with which they were present in the extractions reported in this study: those elements that were not extracted in reportable quantities from any of the test articles under any of the extraction conditions, those elements that were rarely extracted from the test articles at reportable levels, those elements that were infrequently extracted from the test articles at reportable levels, and those elements that were more frequently present in the extracts in reportable quantities.

Determination of elemental impurities and U and O isotopic compositions with a view to identify the geographical and industrial origins of uranium ore concentrates

NASA Astrophysics Data System (ADS)

Salaun, A.; Hubert, A.; Pointurier, F.; Aupiais, J.; Pili, E.; Richon, P.; Fauré, A.; Diallo, S.

2012-12-01

First events of illicit trafficking of nuclear and radiological materials occurred 50 years ago. Nuclear forensics expertise are aiming at determining the use of seized material, its industrial history and provenance (geographical area, place of production or processing), at assisting in the identification and dismantling of illicit trafficking networks. This information is also valuable in the context of inspections of declared facilities to verify the consistency of operator's declaration. Several characteristics can be used to determine the origin of uranium ore concentrates such as trace elemental impurity patterns (Keegan et al., 2008 ; Varga et al., 2010a, 2010b) or uranium, oxygen and lead isotopic compositions (Tamborini et al., 2002a, 2002b ; Wallenius et al., 2006; Varga et al., 2009). We developed analytical procedures for measuring the isotopic compositions of uranium (234U/238U and 235U/238U) and oxygen (18O/16O) and levels of elemental impurities (e.g. REE, Th) from very small amounts of uranium ore concentrates (or yellow cakes). Micrometer particles and few milligrams of material are used for oxygen isotope measurements and REE determination, respectively. Reference materials were analyzed by mass spectrometry (TIMS, SF-ICP-MS and SIMS) to validate testing protocols. Finally, materials of unknown origin were analyzed to highlight significant differences and determine whether these differences allow identifying the origin of these ore concentrates. References: Keegan, E., et al. (2008). Applied Geochemistry 23, 765-777. Tamborini, G., et al. (2002a). Analytical Chemistry 74, 6098-6101. Tamborini, G., et al. (2002b). Microchimica Acta 139, 185-188. Varga, Z., et al. (2009). Analytical Chemistry 81, 8327-8334. Varga, Z., et al. (2010a). Talanta 80, 1744-1749. Varga, Z., et al. (2010b). Radiochimica Acta 98, 771-778 Wallenius, M., et al. (2006). Forensic Science International 156, 55-62.

Astrophysics with Presolar Stardust

NASA Astrophysics Data System (ADS)

Clayton, Donald D.; Nittler, Larry R.

2004-09-01

Meteorites and interplanetary dust particles contain presolar stardust grains: solid samples of stars that can be studied in the laboratory. The stellar origin of the grains is indicated by enormous isotopic ratio variations compared with Solar System materials, explainable only by nuclear reactions occurring in stars. Known presolar phases include diamond, SiC, graphite, Si3N4, Al2O3, MgAl2O4, CaAl12O19, TiO2, Mg(Cr,Al)2O4, and most recently, silicates. Subgrains of refractory carbides (e.g., TiC), and Fe-Ni metal have also been observed within individual presolar graphite grains. We review the astrophysical implications of these grains for the sciences of nucleosynthesis, stellar evolution, grain condensation, and the chemical and dynamic evolution of the Galaxy. Unique scientific information derives primarily from the high precision (in some cases <1%) of the measured isotopic ratios of large numbers of elements in single stardust grains. Stardust science is just now reaching maturity and will play an increasingly important role in nucleosynthesis applications.

Novel AlInN/GaN integrated circuits operating up to 500 °C

NASA Astrophysics Data System (ADS)

Gaska, R.; Gaevski, M.; Jain, R.; Deng, J.; Islam, M.; Simin, G.; Shur, M.

2015-11-01

High electron concentration in 2DEG channel of AlInN/GaN devices is remarkably stable over a broad temperature range, enabling device operation above 500 °C. The developed IC technology is based on three key elements: (1) exceptional quality AlInN/GaN heterostructure with very high carrier concentration and mobility enables IC fast operation in a broad temperature range; (2) heterostructure field effect transistor approach t provides fully planar IC structure which is easy to scale and to combine with the other high temperature electronic components; (3) fabrication advancements including novel metallization scheme and high-K passivation/gate dielectrics enable high temperature operation. The feasibility of the developed technology was confirmed by fabrication and testing of the high temperature inverter and differential amplifier ICs using AlInN/GaN heterostructures. The developed ICs showed stable performance with unit-gain bandwidth above 1 MHz and internal response time 45 ns at temperatures as high as 500 °C.

Geochemistry of the Nsuta Mn deposit in Ghana: Implications for the Paleoproterozoic atmosphere and ocean chemistry

NASA Astrophysics Data System (ADS)

Goto, K. T.; Ito, T.; Suzuki, K.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

2013-12-01

Oxygenation of the atmosphere and oceans has influenced the evolution of ocean chemistry and diversification of early life. A number of large manganese (Mn) deposits are distributed in the Paleoproterozoic sedimentary successions that were formed during the great oxidation event (GOE) around 2.4-2.2 Ga (Meynard, 2010). Due to the high redox potential of Mn, occurrences of Mn deposits have been regarded as important evidence for a highly oxidized environment during the Paleoproterozoic (Kirschvink et al., 2000). Furthermore, because Mn oxides strongly adsorb various elements, including bioessential elements such as Mo, formation of large Mn deposits may have affected the seawater chemical composition and ecology during the Paleoproterozoic. However, the genesis of each Mn deposit is poorly constrained, and the relationships among the formation of Mn deposits, the evolution of atmospheric and ocean chemistry, and the diversification of early life are still ambiguous. In this study, we report the Re-Os isotope compositions, rare earth element (REE) compositions, and abundance of manganophile elements in the Mn carbonate ore and host sedimentary rock samples collected from the Nsuta Mn deposit of the Birimian Supergroup, Ghana. The Nsuta deposit is one of the largest Paleoproterozoic Mn deposits, although its genesis remains controversial (Melcher et al., 1995; Mucke et al., 1999). The composite Re-Os isochron age (2149 × 130 Ma) of the Mn carbonate and sedimentary rock samples was consistent with the depositional age of the sedimentary rocks (~2.2 Ga) presumed from the U-Pb zircon age of volcanic rocks (Hirdes and Davis, 1998), suggesting that the timing of Mn ore deposition was almost equivalent to the host rock sedimentation. The PAAS-normalized REE pattern showed a positive Eu anomaly in all samples and a positive Ce anomaly only in the Mn carbonate ore. These REE patterns indicate the possible contribution of Eu-enriched fluids derived from hydrothermal activity and Ce enrichment due to the oxidation of Ce(III) by Mn(IV) during an ore formation. Among the manganophile elements, merely Mo is enriched in the Mn carbonate ore compared with the host sedimentary rocks. The profile of manganophile elements was similar to that of modern hydrothermal Mn oxide (Kuhn et al., 2003), although the exact Mo concentration was much lower. These geochemical lines of evidence provide the following plausible genetic model for the Nsuta deposits: (1) Mn(II) was derived from hydrothermal vents, (2) Mn(II) was oxidized to Mn(IV) oxide by the oxygenated seawater, (3) the precipitation of Mn oxide is almost concurrent with the deposition of the host sedimentary rocks, (4) Mn oxide was diagenetically transformed to be a Mn carbonate ore. The geochemical features of the Nsuta deposits suggest that, as in the present oxic oceans, Mn oxide was a potential sink for several trace elements in the Paleoproterozoic oceans. The low-Mo concentration in the Mn carbonate ore probably reflects the large difference between the chemical compositions of Paleoproterozoic and present seawater, implying the prevalence of reduced marine conditions even during the GOE (Scott et al., 2008)

Magma evolution as seen through zircon geochemistry: an example from the Southern Adamello Batholith, N. Italy

NASA Astrophysics Data System (ADS)

Broderick, C.; Schaltegger, U.; Gerdes, A.; Frick, D.; Guenther, D.; Brack, P.

2012-04-01

Zircon is an ubiquitous accessory mineral often used for U-Pb geochronology but is also an important recorder of geochemical information. The trace element and isotopic characteristics of zircon yield potential for tracking changes in an evolving magma through time. With recent advances in U-Pb zircon geochronology, 10-100 ka to Ma timescales are observed for incremental pluton construction (Michel et al., 2008, Schaltegger et al., 2009). In observed 100 ka timescales of zircon crystallization, can zircon record the processes that produce trace element variations in a magma? This study focuses on the Val Fredda Complex (VFC) in the southern tip of the 43 to 33 Ma Adamello batholith, N. Italy. The VFC displays complex relationships among mafic melts that were injected into solidifying felsic magmas. Single zircon crystals were dated using CA-ID-TIMS. With permil uncertainties on 206Pb/238U zircon dates, zircons reveal complexities within single populations. The mafic units crystallized potential autocrystic zircons over a duration of 100 - 150ka, whereas the felsic units record up to 200ka of zircon crystallization. In order to understand these complex zircon populations, we analyzed Hf isotopes and trace elements, on the same volume of zircon used for U-Pb dating, following the TIMS-TEA method (Schoene et al., 2010). This detailed zircon study will allow us to look at how magmas are evolving with time. Hf isotopes of VFC mafic zircons reveal distinct ɛHf values between the three mafic units and their ɛHf values remain consistent through time, whereas the VFC felsic units record more complexity in their ɛHf values. We observe changes such as increasing and slight decreases in ɛHf with time which suggest different processes are occurring to produce the different felsic units. Trace element ratios in zircon reveal differences which allow us to make distinctions between felsic and mafic units (e.g. Th/U, (Lu/Gd)N, REEs). The VFC records 200 ka of zircon crystallization and our data suggests that zircons do in fact reflect changes in isotopic and in trace element signatures on 100 ka timescales. Although we observe changes in our trace elements, the TIMS-TEA method provides an average of trace element concentrations from a zircon volume, dominated by more marginal growth zones. Therefore we will compare our data with in situ methods to determine how our trace element data compares with trace elements across zircon profiles. We acknowledge funding of FNS in the frame of ProDoc Adamello 4-D. Michel et al., 2008, Geol. 36 : 459-462 ; Schaltegger et al., 2009, Earth Planet. Sci.Lett. 286: 208-218; Schoene et al., 2010, Geochim. Cosmochim. Acta 74, 7144-7159.

On the Development of Multi-Step Inverse FEM with Shell Model

NASA Astrophysics Data System (ADS)

Huang, Y.; Du, R.

2005-08-01

The inverse or one-step finite element approach is increasingly used in the sheet metal stamping industry to predict strain distribution and the initial blank shape in the preliminary design stage. Based on the existing theory, there are two types of method: one is based on the principle of virtual work and the other is based on the principle of extreme work. Much research has been conducted to improve the accuracy of simulation results. For example, based on the virtual work principle, Batoz et al. developed a new method using triangular DKT shell elements. In this new method, the bending and unbending effects are considered. Based on the principle of extreme work, Majlessi and et al. proposed the multi-step inverse approach with membrane elements and applied it to an axis-symmetric part. Lee and et al. presented an axis-symmetric shell element model to solve the similar problem. In this paper, a new multi-step inverse method is introduced with no limitation on the workpiece shape. It is a shell element model based on the virtual work principle. The new method is validated by means of comparing to the commercial software system (PAMSTAMP®). The comparison results indicate that the accuracy is good.

The effects of minor elements in La0.6Sr0.4Co0.2Fe0.8O3-δ cathodes on oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Oishi, Junya; Otomo, Junichiro; Oshima, Yoshito; Koyama, Michihisa

2015-03-01

It is known that the minor elements affect the performance of solid oxide fuel cell (SOFC). In this study, we focus on the influence of minor elements on the SOFC cathode properties. The Ca, Ba, Al, and Si, which originate from raw materials and production processes for SOFC cathodes, are investigated as minor elements that may have effect on the properties of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode. To examine the effects of minor elements on the cathode properties, Ca, Ba, Al, and Si with a controlled concentration are added to the LSCF reference sample. Conductivity relaxation measurements are conducted to determine the chemical diffusion coefficient (Dchem) and surface exchange coefficient (ktr), which governs the overpotential characteristics of the LSCF cathode. The results show that Al and Si have negative effects on both Dchem and ktr while Ca and Ba do not alter Dchem and show weakly positive effects on ktr. The effects of Ca and Ba for the cathode properties are discussed on the basis of XPS measurements.

Trace elements in fish from the Arabian Gulf and the Shatt al-Arab river, Iraq

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abaychi, J.; Al-Saad, H.T.

1988-02-01

In the Arabian Gulf region, recently, vast industrial, agricultural, economic and social developments have taken place, in addition to an increase in population. This may enhance the magnitude of environmental pollution year by year. No detailed study has been undertaken to assess the concentrations of trace elements in commercial species of fish from the Arabian Gulf and the Shatt al-Arab River, despite the fact that fish are considered an essential part of the diet in the region. Therefore, an investigation was carried out on the concentration of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in themore » following fish species from the Arabian Gulf: Tylosurus strongylurus, Eleutheoronema tetradactum, Pomadasys arel, Platycephalus indicus, Ilisha elongata, Thryssa hamiltonii, Arius thalassinus, Acanthophagrus luteus, Johnieops sina, Liza dussumeiri, Hilsa ilisha, Nematolosa nasus and Otoliths argenteus, and on species from the Shatt al-Arab River: Mesopotamichthys sharpeyi, Barbus xanthopterus, Barbus scheich, Aspius vorax, Cyprinus carpio, and Barbus grypus. Trace element levels in sediment samples from the area were also determined since sediments can accumulate different elements and may reflect the extent of pollution by these elements.« less

Trace element biomonitoring using mosses in urban areas affected by mud volcanoes around Mt. Etna. The case of the Salinelle, Italy.

PubMed

Bonanno, Giuseppe; Lo Giudice, Rosa; Pavone, Pietro

2012-08-01

Trace element impact was assessed using mosses in a densely inhabited area affected by mud volcanoes. Such volcanoes, locally called Salinelle, are phenomena that occur around Mt. Etna (Sicily, Italy) and are interpreted as the surface outflow of a hydrothermal system located below Mt. Etna, releasing sedimentary fluids (hydrocarbons and NaCl brines) along with magmatic gases (mainly CO(2) and He). To date, scarce data are available about the presence of trace elements, and no biomonitoring campaigns are reported about the cumulative effects of such emissions. In this study, concentrations of Al, As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, V, and Zn were detected in the moss Bryum argenteum, in soil and water. Results showed that the trace element contribution of the Salinelle to the general pollution was significant for Al, Mn, Ni, and Zn. The comparison of trace concentrations in mosses from Salinelle and Etna showed that the mud volcanoes release a greater amount of Al and Mn, whereas similar values of Ni were found. Natural emissions of trace elements could be hazardous in human settlements, in particular, the Salinelle seem to play an important role in environmental pollution.

Experimental and Analytical Studies of Solar System Chemistry

NASA Technical Reports Server (NTRS)

Burnett, Donald S.

2003-01-01

The cosmochemistry research funded by this grant resulted in the publications given in the attached Publication List. The research focused in three areas: (1) Experimental studies of trace element partitioning. (2) Studies of the minor element chemistry and O isotopic compositions of MgAlO4 spinels from Ca-Al-Rich Inclusions in carbonaceous chondrite meteorites, and (3) The abundances and chemical fractionations of Th and U in chondritic meteorites.

Transforming Research and Clinical Knowledge in Traumatic Brain Injury

DTIC Science & Technology

2016-12-01

Szuflita, N., Orman, J., and Schwab, K. (2010). Advancing integrated research in psychological health and traumatic brain injury: common data ele- ments...Szuflita N, Orman J, et al. Advancing Integrated Research in Psychological Health and Traumatic Brain Injury: Common Data Elements. Arch Phys Med Rehabil...R, Gleason T, et al. Advancing integrated research in psychological health and traumatic brain injury: common data elements. Arch Phys Med Rehabil

Trace elements in muscle of three fish species from Todos os Santos Bay, Bahia State, Brazil.

PubMed

de Santana, Carolina Oliveira; de Jesus, Taíse Bomfim; de Aguiar, William Moura; de Jesus Sant'anna Franca-Rocha, Washington; Soares, Carlos Alberto Caroso

2017-03-01

In this study, an analysis was performed on the concentrations of the trace elements Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn in muscle of two carnivorous and one planktivorous fish species collected at Todos os Santos Bay (BTS). The accumulation order of the trace elements in Lutjanus analis was Al >Zn >Fe >Cr >Ba >Ni. In Cetengraulis edentulus, the order was Al >Fe >Zn >Cr >Ni >Mn >As. In the species Diapterus rhombeus, the order was Al >Fe >Zn >Cr >Ni >Mn >Cd. To determine the risk related to the consumption of fish, toxicity guidelines were used as standard references. It was observed that the species C. edentulus contained concentrations of As exceeding WHO limits, but these concentrations were acceptable according to the Agência Nacional de Vigilância Sanitária (ANVISA) guidelines. Cd levels were found only in D. rhombeus and in low concentrations according to the determinations of WHO and ANVISA. Pb levels were not detected in any of the three fish species. The analyzed elements did not differ statistically according to the species and feeding habits. The results point to possible risks of human contamination by As related to the consumption of the fish species C. edentulus from the BTS.

Low absorption loss p-AlGaN superlattice cladding layer for current-injection deep ultraviolet laser diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martens, M.; Kuhn, C.; Ziffer, E.

2016-04-11

Current injection into AlGaN-based laser diode structures with high aluminum mole fractions for deep ultraviolet emission is investigated. The electrical characteristics of laser diode structures with different p-AlGaN short period superlattice (SPSL) cladding layers with various aluminum mole fractions are compared. The heterostructures contain all elements that are needed for a current-injection laser diode including cladding and waveguide layers as well as an AlGaN quantum well active region emitting near 270 nm. We found that with increasing aluminum content in the p-AlGaN cladding, the diode turn-on voltage increases, while the series resistance slightly decreases. By introducing an SPSL instead of bulkmore » layers, the operating voltage is significantly reduced. A gain guided broad area laser diode structure with transparent p-Al{sub 0.70}Ga{sub 0.30}N waveguide layers and a transparent p-cladding with an average aluminum content of 81% was designed for strong confinement of the transverse optical mode and low optical losses. Using an optimized SPSL, this diode could sustain current densities of more than 4.5 kA/cm{sup 2}.« less

Preferential site occupancy of alloying elements in TiAl-based phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holec, David, E-mail: david.holec@unileoben.ac.at; Reddy, Rajeev K.; Klein, Thomas

2016-05-28

First principles calculations are used to study the preferential occupation of ternary alloying additions into the binary Ti-Al phases, namely, γ-TiAl, α{sub 2}-Ti{sub 3}Al, β{sub o}-TiAl, and B19-TiAl. While the early transition metals (TMs, group IVB, VB, and VIB elements) prefer to substitute for Ti atoms in the γ-, α{sub 2}-, and B19-phases, they preferentially occupy Al sites in the β{sub o}-TiAl. Si is, in this context, an anomaly, as it prefers to sit on the Al sublattice for all four phases. B and C are shown to prefer octahedral Ti-rich interstitial positions instead of substitutional incorporation. The site preferencemore » energy is linked with the alloying-induced changes of energy of formation, hence alloying-related (de)stabilisation of the phases. We further show that the phase-stabilisation effect of early TMs on β{sub o}-phase has a different origin depending on their valency. Finally, an extensive comparison of our predictions with available theoretical and experimental data (which is, however, limited mostly to the γ-phase) shows a consistent picture.« less

A miniaturised laser ablation/ionisation analyser for investigation of elemental/isotopic composition with the sub-ppm detection sensitivity

NASA Astrophysics Data System (ADS)

Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

2012-04-01

Detailed knowledge of the elemental and isotopic composition of solar system objects imposes critical constraints on models describing the origin of our solar system and can provide insight to chemical and physical processes taking place during the planetary evolution. So far, the investigation of chemical composition of planetary surfaces could be conducted almost exclusively by remotely controlled spectroscopic instruments from orbiting spacecraft, landers or rovers. With some exceptions, the sensitivity of these techniques is, however, limited and often only abundant elements can be investigated. Nevertheless, the spectroscopic techniques proved to be successful for global chemical mapping of entire planetary objects such as the Moon, Mars and asteroids. A combined afford of the measurements from orbit, landers and rovers can also yield the determination of local mineralogy. New instruments including Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation/Ionisation Mass Spectrometer (LIMS), have been recently included for several landed missions. LIBS is thought to improve flexibility of the investigations and offers a well localised chemical probing from distances up to 10-13 m. Since LIMS is a mass spectrometric technique it allows for very sensitive measurements of elements and isotopes. We will demonstrate the results of the current performance tests obtained by application of a miniaturised laser ablation/ionisation mass spectrometer, a LIMS instrument, developed in Bern for the chemical analysis of solids. So far, the only LIMS instrument on a spacecraft is the LAZMA instrument. This spectrometer was a part of the payload for PHOBOS-GRUNT mission and is also currently selected for LUNA-RESURCE and LUNA-GLOB missions to the lunar south poles (Managadze et al., 2011). Our LIMS instrument has the dimensions of 120 x Ø60 mm and with a weight of about 1.5 kg (all electronics included), it is the lightest mass analyser designed for in situ chemical analysis of solid materials on the planetary surfaces (Rohner et al., 2003). Initial laboratory tests that were conducted with an IR laser radiation for the ablation, atomisation and ionisation of the material, indicated a high performance of the instrument in terms of sensitivity, dynamic range and mass resolution (Tulej et al., 2011). After some technical improvements and implementation of a computer-controlled performance optimiser we have achieved further improvements of both, the instrumental sensitivity down to sub-ppm level and reproducibility of the measurements. We will demonstrate the potential of the mass analyser to perform the quantitative elemental analysis of solids with a spatial (vertical, lateral) resolution commensurate with typical grain sizes, and its capabilities for investigation of isotopic patterns with accuracy and precision comparable to that of large analytical laboratory instruments, e.g., TIMS, SIMS, LA-ICP-MS. The results can be of considerable interest for in situ dating or investigation of other fine isotopic fractionation effects including studies of bio-markers.

Lunar bulk chemical composition: a post-Gravity Recovery and Interior Laboratory reassessment

PubMed Central

Taylor, G. Jeffrey; Wieczorek, Mark A.

2014-01-01

New estimates of the thickness of the lunar highlands crust based on data from the Gravity Recovery and Interior Laboratory mission, allow us to reassess the abundances of refractory elements in the Moon. Previous estimates of the Moon fall into two distinct groups: earthlike and a 50% enrichment in the Moon compared with the Earth. Revised crustal thicknesses and compositional information from remote sensing and lunar samples indicate that the crust contributes 1.13–1.85 wt% Al2O3 to the bulk Moon abundance. Mare basalt Al2O3 concentrations (8–10 wt%) and Al2O3 partitioning behaviour between melt and pyroxene during partial melting indicate mantle Al2O3 concentration in the range 1.3–3.1 wt%, depending on the relative amounts of pyroxene and olivine. Using crustal and mantle mass fractions, we show that that the Moon and the Earth most likely have the same (within 20%) concentrations of refractory elements. This allows us to use correlations between pairs of refractory and volatile elements to confirm that lunar abundances of moderately volatile elements such as K, Rb and Cs are depleted by 75% in the Moon compared with the Earth and that highly volatile elements, such as Tl and Cd, are depleted by 99%. The earthlike refractory abundances and depleted volatile abundances are strong constraints on lunar formation processes. PMID:25114309

Lunar bulk chemical composition: a post-Gravity Recovery and Interior Laboratory reassessment.

PubMed

Taylor, G Jeffrey; Wieczorek, Mark A

2014-09-13

New estimates of the thickness of the lunar highlands crust based on data from the Gravity Recovery and Interior Laboratory mission, allow us to reassess the abundances of refractory elements in the Moon. Previous estimates of the Moon fall into two distinct groups: earthlike and a 50% enrichment in the Moon compared with the Earth. Revised crustal thicknesses and compositional information from remote sensing and lunar samples indicate that the crust contributes 1.13-1.85 wt% Al2O3 to the bulk Moon abundance. Mare basalt Al2O3 concentrations (8-10 wt%) and Al2O3 partitioning behaviour between melt and pyroxene during partial melting indicate mantle Al2O3 concentration in the range 1.3-3.1 wt%, depending on the relative amounts of pyroxene and olivine. Using crustal and mantle mass fractions, we show that that the Moon and the Earth most likely have the same (within 20%) concentrations of refractory elements. This allows us to use correlations between pairs of refractory and volatile elements to confirm that lunar abundances of moderately volatile elements such as K, Rb and Cs are depleted by 75% in the Moon compared with the Earth and that highly volatile elements, such as Tl and Cd, are depleted by 99%. The earthlike refractory abundances and depleted volatile abundances are strong constraints on lunar formation processes. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Imaging of glial cell morphology, SOD1 distribution and elemental composition in the brainstem and hippocampus of the ALS hSOD1G93A rat.

PubMed

Stamenković, Stefan; Dučić, Tanja; Stamenković, Vera; Kranz, Alexander; Andjus, Pavle R

2017-08-15

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor and cognitive domains of the CNS. Mutations in the Cu,Zn-superoxide dismutase (SOD1) cause 20% of familial ALS and provoke formation of intracellular aggregates and copper and zinc unbinding, leading to glial activation and neurodegeneration. Therefore, we investigated glial cell morphology, intracellular SOD1 distribution, and elemental composition in the brainstem and hippocampus of the hSOD1 G93A transgenic rat model of ALS. Immunostaining for astrocytes, microglia and SOD1 revealed glial proliferation and progressive tissue accumulation of SOD1 in both brain regions of ALS rats starting already at the presymptomatic stage. Glial cell morphology analysis in the brainstem of ALS rats revealed astrocyte activation occurring before disease symptoms onset, followed by activation of microglia. Hippocampal ALS astrocytes exhibited an identical reactive profile, while microglial morphology was unchanged. Additionally, ALS brainstem astrocytes demonstrated progressive SOD1 accumulation in the cell body and processes, while microglial SOD1 levels were reduced and its distribution limited to distal cell processes. In the hippocampus both glial cell types exhibited SOD1 accumulation in the cell body. X-ray fluorescence imaging revealed decreased P and increased Ca, Cl, K, Ni, Cu and Zn in the brainstem, and higher levels of Cl, Ni and Cu, but lower levels of Zn in the hippocampus of symptomatic ALS rats. These results bring new insights into the glial response during disease development and progression in motor as well as in non-motor CNS structures, and indicate disturbed tissue elemental homeostasis as a prominent hallmark of disease pathology. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Occurrence of high-Al N-MORB along the Easternmost Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Meyzen, C. M.; Humler, E.; Ludden, J. N.

2017-12-01

One of the deepest and slowest part of the mid-ocean-ridge system lies within the easternmost part of the Southwest Indian Ridge between 61°E and 69° E. In this region, a distinctive sea-floor terrain characterized by high-relief segments separated by long, deep tectonized sections shows a predominance of tectonic over magmatic extensional processes, suggesting an unstable and weak, but locally focalized magma supply. Other features of this section include the absence of long-lived transforms, thick lithosphere, high upper mantle seismic wave velocities and thin oceanic crust (4-5 km). When compared to other ridge segments, most MORB erupted along this section distinguish themselves by their higher Na2O, Sr and Al2O3 compositions, very low CaO/Al2O3 ratios relative to TiO2 and depleted heavy rare-earth element (REE) distributions. Another peculiar feature is their subparallel LREE enriched patterns. The high-Al-MgO magma type erupted periodically around the ridge system is also found in this region at 61.93°E. These lavas are characterized by high Al2O3 (> 17 wt. %), MgO (> 8.8 wt. %) and FeO contents, low SiO2 (< 49 wt. %) and Na2O and very low TiO2 (< 1 wt. %), and a LREE depleted pattern compared to the main population. At slightly lower MgO, sporadically, two other dredges located at 63.36-63.66°E share some of these distinct compositional characteristics. As a whole, these lavas are the most depleted in highly incompatible elements, but are also characterized by an offset toward lower MREE/HREE ratios relative to the main population. These peculiar basalts are not parental to the more common lower MgO compositions and cannot be related to them by fractional crystallization alone. Instead, their major element features, and the occasional presence of positive Eu and Sr anomalies might indicate assimilation of plagioclase cumulates, while their offset in MREE/HREE might require a multistage melting evolution with an earlier event in the garnet stability field.

[Aluminum--occurrence and toxicity for organisms].

PubMed

Ochmański, W; Barabasz, W

2000-01-01

Aluminium (Al.) is an ubiquitous element found in every food product. The sources of Al. are especially corn, yellow cheese, salt, herbs, spices, tea and tap water. In household Al.-made ware is a major source of the element. Al. may cause diseases in humans, especially hampers many metabolic processes especially turnover of calcium, phosphorus and iron. Salts of Al. may bind to DNA, RNA, inhibit such enzymes as hexokinase, acid and alkaline phosphatases, phosphodiesterase and phosphooxydase. Al. salts are especially harmful to nervous, hematopoietic systems and to skeleton. Al. gets to organism with food, water, cosmetics, from aluminium ware and containers. Toxicity comes from substitution of Mg and Fe ions effecting in disturbances in intracellular signaling, excretory functions and cellular growth. Neurotoxic action of Al. probably comes from substitution of Mg ions in ATP, what finally influences function of every ATP using-enzymes. There are observations in experimental models proving Al. salts are responsible for Alzheimer disease development. Toxicity of Al. to skeletal system results in diminished resistance thus tendencies to breaking, and comes from lower collagen synthesis and slowing down of mineralisation. Low erythropoietin production, inhibition of hem-synthesing enzymes and binding of Al. to transferrin, effects in anaemia. Carcinogenic effects of Al. were nor proved nor denied, but high concentrations of Al. were found in many neoplastic cells. In conclusion, we should introduce prophylactic measures effecting in less Al. intake esp. avoiding use of Al.-made ware nad controlling food for Al. content.

A Novel Synthesis Routine for Woodwardite and Its Affinity towards Light (La, Ce, Nd) and Heavy (Gd and Y) Rare Earth Elements.

PubMed

Consani, Sirio; Balić-Žunić, Tonci; Cardinale, Anna Maria; Sgroi, Walter; Giuli, Gabriele; Carbone, Cristina

2018-01-14

A synthetic Cu-Al-SO₄ layered double hydroxide (LDH), analogue to the mineral woodwardite [Cu 1-x Al x (SO₄) x/2 (OH)₂·nH₂O], with x < 0.5 and n ≤ 3x/2, was synthesised by adding a solution of Cu and Al sulphates to a solution with NaOH. The pH values were kept constant at 8.0 and 10.0 by a continuous addition of NaOH. The material obtained had poor crystallinity, turbostratic structure, and consisted of nanoscopic crystallites. The analyses performed in order to characterise the obtained materials (X-ray diffraction (XRD), thermogravimetry (TG), and Fourier Transform Infra-Red (FTIR) spectroscopy) showed that the Cu-Al-SO₄ LDH is very similar to woodwardite, although it has a smaller layer spacing, presumably due to a lesser water content than in natural samples. The synthesis was performed by adding light rare earth elements (LREEs) (La, Ce, and Nd) and heavy rare earth elements (HREEs) (Gd and Y) in order to test the affinity of the Cu-Al-SO₄ LDH to the incorporation of REEs. The concentration of rare earth elements (REEs) in the solid fraction was in the range of 3.5-8 wt %. The results showed a good affinity for HREE and Nd, especially for materials synthesised at pH 10.0, whereas the affinities for Ce and La were much lower or non-existent. The thermal decomposition of the REE-doped materials generates a mixture of Cu, Al, and REE oxides, making them interesting as precursors in REE oxide synthesis.

Observation of New Spontaneous Fission Activities from Elements 100 TO 105.

NASA Astrophysics Data System (ADS)

Somerville, Lawrence Patrick

Several new Spontaneous Fission (SF) activities have been found. Their half-lives and production cross sections in several reactions have been measured by collecting and transporting recoils at known speed past mica track detectors. No definite identification could be made for any of the new SF activities; however, half-lives and possible assignments to element-104 isotopes consistent with several cross bombardments include ('257)Rf(3.8 s, 14% SF), ('258)Rf(13 ms), ('259)Rf((TURN)3 s, 8% SF), ('260)Rf((TURN)20 ms), and ('262)Rf((TURN)50ms). The 80-ms SF activity claimed by the Dubna group for the discovery of element 104 (('260)104) was not observed. A difficulty exists in the interpretation that ('260)Rf is a (TURN)20-ms SF activity: in order to be correct, for example, the SF activities with half-lives between 14 and 24 ms produced in the reactions 109- to 119-MeV ('18)O + ('248)Cm, 88- to 100-MeV ('15)N + ('249)Bk, and 96-MeV ('18)O + ('249)Cf must be other nuclides due to their large production cross sections, or the cross sections for production of ('260)Rf must be enhanced by unknown mechanisms. Based on calculated total production cross sections a possible (TURN)1% electron-capture branch in ('258)Lr(4.5 s) to the SF emitter ('258)No(1.2 ms) and an upper limit of 0.05% for SF branching in ('254)No(55 s) were determined. Other measured half-lives from unknown nuclides produced in respective reactions include (TURN)1.6 s (('18)O + ('248)Cm), indications of a (TURN)47-s SF activity (75-MeV ('12)C + ('249)Cf), and two or more SF activities with 3 s (LESSTHEQ) T(, 1/2) (LESSTHEQ) 60 s (('18)O + ('249)Bk). The most exciting conclusion of this work is that if the tentative assignments to even-even element -104 isotopes are correct, there would be a sudden change in the SF half-life systematics at element 104 which has been predicted theoretically by Randrup et al. and Baran et al. and attributed to the disappearance of the second hump of the double-humped fission barrier. This disappearance of the second barrier also explains the tentative low hindrance factors compared to lighter elements for SF of the odd -mass isotopes ('257)Rf((TURN)4 x 10('3)) and ('259)Rf((TURN)2 x 10('3)). On the basis of recent odd-mass alpha-decay energy data, the 152-neutron sub-shell effect is probably weaker for element 104 than for element 102, confirming predictions of Randrup et al., and not strong enough to significantly alter the SF half-life predictions. This weakening sub-shell effect is in contrast to the continuing strong effect assumed in the Ghiorso half-life systematics. The possibilities of enhanced stability against SF with 157 neutrons for ('261)RF(65 s) and theoretical arguments concerning the SF-mass distributions for element-104 nuclei are discussed.

Short-term low-severity spring grassland fire impacts on soil extractable elements and soil ratios in Lithuania.

PubMed

Pereira, Paulo; Cerda, Artemi; Martin, Deborah; Úbeda, Xavier; Depellegrin, Daniel; Novara, Agata; Martínez-Murillo, Juan F; Brevik, Eric C; Menshov, Oleksandr; Comino, Jesus Rodrigo; Miesel, Jessica

2017-02-01

Spring grassland fires are common in boreal areas as a consequence of slash and burn agriculture used to remove dry grass to increase soil nutrient properties and crop production. However, few works have investigated fire impacts on these grassland ecosystems, especially in the immediate period after the fire. The objective of this work was to study the short-term impacts of a spring grassland fire in Lithuania. Four days after the fire we established a 400m 2 sampling grid within the burned area and in an adjacent unburned area with the same topographical, hydrological and pedological characteristics. We collected topsoil samples immediately after the fire (0months), 2, 5, 7 and 9months after the fire. We analysed soil pH, electrical conductivity (EC), major nutrients including calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K), and the minor elements aluminium (Al), manganese (Mn), iron (Fe) and zinc (Zn). We also calculated the soil Na and K adsorption ratio (SPAR), Ca:Mg and Ca:Al. The results showed that this low-severity grassland fire significantly decreased soil pH, Al, and Mn but increased EC, Ca, Mg, and K,. There was no effect on Na, Fe, and Zn. There was a decrease of EC, Ca, Mg, and Na from 0months after the fire until 7months after the fire, with an increase during the last sampling period. Fire did not significantly affect SPAR. Ca:Mg decreased significantly immediately after the fire, but not to critical levels. Ca:Al increased after the fire, reducing the potential effects of Al on plants. Overall, fire impacts were mainly limited to the immediate period after the fire. Copyright © 2016 Elsevier B.V. All rights reserved.

Forbidden transition probabilities for ground terms of ions with p or p5 configurations. [for solar atmosphere

NASA Technical Reports Server (NTRS)

Kastner, S. O.

1976-01-01

Forbidden transition probabilities are given for ground term transitions of ions in the isoelectronic sequences with outer configurations 2s2 2p (B I), 2p5 (F I), 3s2 3p (Al I), and 3p5 (Cl I). Tables give, for each ion, the ground term interval, the associated wavelength, the quadrupole radial integral, the electric quadrupole transition probability, and the magnetic dipole transition probability. Coronal lines due to some of these ions have been observed, while others are yet to be observed. The tales for the Al I and Cl I sequences include elements up to germanium.

A six-parameter Iwan model and its application

NASA Astrophysics Data System (ADS)

Li, Yikun; Hao, Zhiming

2016-02-01

Iwan model is a practical tool to describe the constitutive behaviors of joints. In this paper, a six-parameter Iwan model based on a truncated power-law distribution with two Dirac delta functions is proposed, which gives a more comprehensive description of joints than the previous Iwan models. Its analytical expressions including backbone curve, unloading curves and energy dissipation are deduced. Parameter identification procedures and the discretization method are also provided. A model application based on Segalman et al.'s experiment works with bolted joints is carried out. Simulation effects of different numbers of Jenkins elements are discussed. The results indicate that the six-parameter Iwan model can be used to accurately reproduce the experimental phenomena of joints.

Sequential Electrolytic Degradation of Energetic Compounds in Groundwater

DTIC Science & Technology

2004-11-12

Investigators: Dave Gilbert, Ph.D. and Tom Sale, Ph.D. Date: November 12, 2004 Revision: 1.0 Distribution Statement A: Approved for...Degradation of Energetic Compounds in Groundwater 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dave Gilbert, Ph.D. and...catholyte include MNX and nitramide indicating that reduction pathways suggested by others are likely ( Bonin , et al., 2004). As in the TNT

Corrosion resistant PEM fuel cell

DOEpatents

Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen Joel; Doll, Gary Lynn

2001-07-17

The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

Corrosion resistant PEM fuel cell

DOEpatents

Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen Joel; Doll, Gary Lynn

2002-01-01

The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

Corrosion resistant PEM fuel cell

DOEpatents

Li, Yang; Meng, Wen-Jin; Swathirajan, Swathy; Harris, Stephen J.; Doll, Gary L.

1997-01-01

The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell's operating environment. Stainless steels rich in CR, Ni, and Mo are particularly effective protective interlayers.

Small scale heterogeneity of Phanerozoic lower crust: evidence from isotopic and geochemical systematics of mid-Cretaceous granulite gneisses, San Gabriel Mountains, southern California

USGS Publications Warehouse

Barth, A.P.; Wooden, J.L.; May, D.J.

1992-01-01

An elongate belt of mid-Cretaceous, compositionally banded gneisses and granulites is exposed in Cucamonga terrane, in the southeastern foothills of the San Gabriel Mountains of southern California. Banded gneisses include mafic granulites of two geochemical types: type 1 rocks are similar to high Al arc basalts and andesites but have higher HFSE (high-field-strength-element) abundances and extremely variable LILE (largeion-lithophile-element) abundances, while type 2 rocks are relatively low in Al and similar to alkali rich MOR (midocean-ridge) or intraplate basalts. Intercalated with mafic granulites are paragneisses which include felsic granulites, aluminous gneisses, marble, and calc-silicate gneisses. Type 1 mafic granulites and calcic trondhjemitic pegmatites also oceur as cross-cutting, synmetamorphic dikes or small plutons. Small-scale heterogeneity of deep continental crust is indicated by the lithologic and isotopic diversity of intercalated ortho-and paragneisses exposed in Cucamonga terrane. Geochemical and isotopic data indicate that K, Rb, and U depletion and Sm/Nd fractionation were associated with biotite +/- muscovite dehydration reactions in type 1 mafic granulites and aluminous gneisses during high-grade metamorphism. Field relations and model initial isotopic ratios imply a wide range of protolith ages, ranging from Early Proterozoic to Phanerozoic. ?? 1992 Springer-Verlag.

Substitutional alloy of Ce and Al

PubMed Central

Zeng, Qiao-Shi; Ding, Yang; Mao, Wendy L.; Luo, Wei; Blomqvist, Andreas; Ahuja, Rajeev; Yang, Wenge; Shu, Jinfu; Sinogeikin, Stas V.; Meng, Yue; Brewe, Dale L.; Jiang, Jian-Zhong; Mao, Ho-kwang

2009-01-01

The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce3Al intermetallic compound >15 GPa or the Ce3Al metallic glass >25 GPa. Synchrotron X-ray diffraction, Ce L3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions. PMID:19188608

Atom probe tomography of a Ti-Si-Al-C-N coating grown on a cemented carbide substrate.

PubMed

Thuvander, M; Östberg, G; Ahlgren, M; Falk, L K L

2015-12-01

The elemental distribution within a Ti-Si-Al-C-N coating grown by physical vapour deposition on a Cr-doped WC-Co cemented carbide substrate has been investigated by atom probe tomography. Special attention was paid to the coating/substrate interface region. The results indicated a diffusion of substrate binder phase elements into the Ti-N adhesion layer. The composition of this layer, and the Ti-Al-N interlayer present between the adhesion layer and the main Ti-Si-Al-C-N layer, appeared to be sub-stoichiometric. The analysis of the interlayer showed the presence of internal surfaces, possibly grain boundaries, depleted in Al. The composition of the main Ti-Al-Si-C-N layer varied periodically in the growth direction; layers enriched in Ti appeared with a periodicity of around 30 nm. Laser pulsing resulted in a good mass resolution that made it possible to distinguish between N(+) and Si(2+) at 14 Da. Copyright © 2015 Elsevier B.V. All rights reserved.

Laser diode bars based on strain-compensated AlGaPAs/GaAs heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marmalyuk, Aleksandr A; Ladugin, M A; Yarotskaya, I V

2012-01-31

Traditional (in the AlGaAs/GaAs system) and phosphorus-compensated (in the AlGaAs/AlGaPAs/GaAs system) laser heterostructures emitting at a wavelength of 850 nm are grown by MOVPE and studied. Laser diode bars are fabricated and their output characteristics are studied. The method used to grow heterolayers allowed us to control (minimise) mechanical stresses in the AlGaPAs/GaAs laser heterostructure, which made it possible to keep its curvature at the level of the initial curvature of the substrate. It is shown that the use of a compensated AlGaPAs/GaAs heterostructure improves the linear distribution of emitting elements in the near field of laser diode arrays andmore » allows the power - current characteristic to retain its slope at high pump currents owing to a uniform contact of all emitting elements with the heat sink. The radius of curvature of the grown compensated heterostructures turns out to be smaller than that of traditional heterostructures.« less

Partitioning of Large-ion Lithophile Elements Between Aqueous Fluids and Melts: Role of Saline Fluids in Sub-arc Mantle

NASA Astrophysics Data System (ADS)

Kawamoto, T.; Mibe, K.

2014-12-01

Chemical fractionation of slab-derived supercritical fluids can play an important role in elemental transfer from subducting slab to the mantle wedge and arc magmatism [1]. Recent findings of saline fluids from sub-arc mantle peridotite indicate that aqueous fluids in mantle wedge can contain 3.7 wt% NaCl in Ichinomageta, Northeast Japan arc [2] to 5.1 wt% NaCl in Pinatubo, Luzon arc [3]. It is, therefore, important to determine the effect of Cl on the trace element partitioning between aqueous fluids and melts. Synchrotron radiation X-ray fluorescence (XRF) analysis is conducted to know Rb, Sr, and Pb partitioning between aqueous fluids and melts [4]. There is a positive correlation between partition coefficients and pressure, as well as salinity. Two slab-derived components, melt and fluid components, are suggested to explain trace element characteristics of arc-basalts in the Mariana arc [5]. The fluid component is characterized by enrichment of alkali and alkali earth elements. Such features can be explained if the fluid component is a saline fluid, because alkali earth elements and Pb are much less mobile with Cl-free fluids than Cl-rich fluids [4]. We suggest that slab-derived components have compositional features consistent with a saline fluid and a melt, which can be formed through a separation of a slab-derived supercritical fluid [1]. Slab derived supercritical fluids contain Cl, and aqueous fluids inherit much of the Cl and some of the large-ion lithophile elements. [1] Kawamoto et al. 2012, Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism. PNAS, pnas.org/content/109/46/18695 [2] Kumagai et al. Evolution of carbon dioxide bearing saline fluids in the mantle wedge beneath the Northeast Japan arc, CMP [3] Kawamoto et al. 2013, Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab. PNAS, pnas.org/content/110/24/9663 [4] Kawamoto et al. 2014, Large ion lithophile elements delivered by saline fluids to the sub-arc mantle, EPS, earth-planets-space.com/content/66/1/61 [5] Pearce et al. 2005, Geochemical mapping of the Mariana arc-basin system: Implications for the nature and distribution of subduction components. G-cubed, onlinelibrary.wiley.com/doi/10.1029/2004GC000895/full

The multi-factorial origins of Chronic Traumatic Encephalopathy (CTE) symptomology in post-career athletes: The athlete post-career adjustment (AP-CA) model.

PubMed

Gaetz, Michael

2017-05-01

CTE has two prominent components: the pathophysiology that is detected in the brain postmortem and the symptomology that is present in the interval between retirement and end of life. CTE symptomology has been noted to include memory difficulties, aggression, depression, explosivity, and executive dysfunction at early stages progressing to problems with attention, mood swings, visuospatial difficulties, confusion, progressive dementia, and suicidality (e.g. McKee et al. (2012), Omalu et al. (2010a-c), McKee et al. (2009)). There are a number of assumptions embedded within the current CTE literature: The first is the assumption that CTE symptomology reported by athletes and their families is the product of the pathophysiology change detected post-mortem (e.g. McKee et al. (2009)). At present, there is little scientific evidence to suggest that all CTE symptomology is the product of CTE pathophysiology. It has been assumed that CTE pathophysiology causes CTE symptomology (Meehan et al. (2015), Iverson et al. (2016)) but this link has never been scientifically validated. The purpose of the present work is to provide a multi-factorial theoretical framework to account for the symptomology reported by some athletes who sustain neurotrauma during their careers that will lead to a more systematic approach to understanding post-career symptomology. There is significant overlap between the case reports of athletes with post-mortem diagnoses of CTE, and symptom profiles of those with a history of substance use, chronic pain, and athlete career transition stress. The athlete post-career adjustment (AP-CA) model is intended to explain some of the symptoms that athletes experience at the end of their careers or during retirement. The AP-CA model consists of four elements: neurotrauma, chronic pain, substance use, and career transition stress. Based on the existing literature, it is clear that any one of the four elements of the AP-CA model can account for a significant number of CTE symptoms. In addition, depression can be a chronic lifelong co-morbid condition that may be present prior to an athletic career, or may be developed secondary to any of the model elements as shown in Fig. 1. Notably, neurotrauma is a necessary, but not a sufficient condition, for the development of CTE symptomology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of Three Carbon- and Nitrogen-Rich Particles from Comet 81P/WILD

NASA Technical Reports Server (NTRS)

Gallien, J.-P.; Khodja, H.; Herzog, G. F.; Taylor, S.; Koepsell, E.; Daghlian, C. P.; Flynn, G. J.; Sitnitsky, I.; Lanzirotti, A.; Sutton, S. R.;

Exposure of women to trace elements through the skin by direct contact with underwear clothing.

PubMed

Nguyen, Thao; Saleh, Mahmoud A

2017-01-02

Heavy metals pose a potential danger to human health when present in textile materials. In the present study, inductive coupled plasma mass spectrometry (ICPMS) was used to determine the concentrations and the identity of extractable inorganic elements from different brands of women undergarments. A total of 120 samples consisting of 63 cottons, 44 nylons and 13 polyesters manufactured in 14 different countries having different colors were analyzed for their extractable metals contents. Elements analyzed were Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Ti, V and Zn. Cotton undergarments were rich in Al, Fe and Zn, nylon undergarments had high levels of Cr, Cu and Al, while polyester fabrics contained higher levels of Ni and Fe compared to cotton or nylon. With respect to manufacturing countries, China, Egypt and India showed the highest concentrations of metals in all fabrics. With respect to the color, black garments were characteristic by high concentration of Fe, blue colors with Cu, brown garments with Fe and Cu, green garments with Cu and Fe, pink garments with Al, purple garments with Al and Cu and red garments with Cr, Zn and Al. The consumer should be made aware of the potential dangers of these metals in their clothing.

Altered Methylation in Tandem Repeat Element and Elemental Component Levels in Inhalable Air Particles

PubMed Central

Hou, Lifang; Zhang, Xiao; Zheng, Yinan; Wang, Sheng; Dou, Chang; Guo, Liqiong; Byun, Hyang-Min; Motta, Valeria; McCracken, John; Díaz, Anaité; Kang, Choong-Min; Koutrakis, Petros; Bertazzi, Pier Alberto; Li, Jingyun; Schwartz, Joel; Baccarelli, Andrea A.

2014-01-01

Exposure to particulate matter (PM) has been associated with lung cancer risk in epidemiology investigations. Elemental components of PM have been suggested to have critical roles in PM toxicity, but the molecular mechanisms underlying their association with cancer risks remain poorly understood. DNA methylation has emerged as a promising biomarker for environmental-related diseases, including lung cancer. In this study, we evaluated the effects of PM elemental components on methylation of three tandem repeats in a highly-exposed population in Beijing, China. The Beijing Truck Driver Air Pollution Study was conducted shortly before the 2008 Beijing Olympic Games (June 15-July 27, 2008) and included 60 truck drivers and 60 office workers. On two days separated by 1-2 weeks, we measured blood DNA methylation of SATα, NBL2, D4Z4, and personal exposure to eight elemental components in PM2.5, including aluminum (Al), silicon (Si), sulfur (S), potassium (K), calcium (Ca) titanium (Ti), iron (Fe), and zinc (Zn). We estimated the associations of individual elemental component with each tandem repeat methylation in generalized estimating equations (GEE) models adjusted for PM2.5 mass and other covariates. Out of the eight examined elements, NBL2 methylation was positively associated with concentrations of Si (0.121, 95%CI: 0.030; 0.212, FDR=0.047) and Ca (0.065, 95%CI: 0.014; 0.115, FDR=0.047) in truck drivers. In office workers, SATα methylation was positively associated with concentrations of S (0.115, 95%CI: 0.034; 0.196, FDR=0.042). PM-associated differences in blood tandem-repeat methylation may help detect biological effects of the exposure and identify individuals who may eventually experience higher lung cancer risk. PMID:24273195

Effects of Alloying Elements on the Formation of Core-Shell-Structured Reinforcing Particles during Heating of Al-Ti Powder Compacts.

PubMed

Chen, Tijun; Gao, Min; Tong, Yunqi

2018-01-15

To prepare core-shell-structured Ti@compound particle (Ti@compound p ) reinforced Al matrix composite via powder thixoforming, the effects of alloying elements, such as Si, Cu, Mg, and Zn, on the reaction between Ti powders and Al melt, and the microstructure of the resulting reinforcements were investigated during heating of powder compacts at 993 K (720 °C). Simultaneously, the situations of the reinforcing particles in the corresponding semisolid compacts were also studied. Both thermodynamic analysis and experiment results all indicate that Si participated in the reaction and promoted the formation of Al-Ti-Si ternary compounds, while Cu, Mg, and Zn did not take part in the reaction and facilitated Al₃Ti phase to form to different degrees. The first-formed Al-Ti-Si ternary compound was τ1 phase, and then it gradually transformed into (Al,Si)₃Ti phase. The proportion and existing time of τ1 phase all increased as the Si content increased. In contrast, Mg had the largest, Cu had the least, and Si and Zn had an equivalent middle effect on accelerating the reaction. The thicker the reaction shell was, the larger the stress generated in the shell was, and thus the looser the shell microstructure was. The stress generated in (Al,Si)₃Ti phase was larger than that in τ1 phase, but smaller than that in Al₃Ti phase. So, the shells in the Al-Ti-Si system were more compact than those in the other systems, and Si element was beneficial to obtain thick and compact compound shells. Most of the above results were consistent to those in the semisolid state ones except the product phase constituents in the Al-Ti-Mg system and the reaction rate in the Al-Ti-Zn system. More importantly, the desirable core-shell structured Ti@compound p was only achieved in the semisolid Al-Ti-Si system.

Phosphorus application reduces aluminum toxicity in two Eucalyptus clones by increasing its accumulation in roots and decreasing its content in leaves

PubMed Central

Kang, Yachao; Hou, Wenjuan; Hu, Houzhen; Luo, Wenji; Wei, Jie; Wang, Linghui; Zhang, Boyu

2018-01-01

Under acidic conditions, aluminum (Al) toxicity is an important factor limiting plant productivity; however, the application of phosphorus (P) might alleviate the toxic effects of Al. In this study, seedlings of two vegetatively propagated Eucalyptus clones, E. grandis × E. urophylla ‘G9’ and E. grandis × E. urophylla ‘DH32-29’were subjected to six treatments (two levels of Al stress and three levels of P). Under excessive Al stress, root Al content was higher, whereas shoot and leaf Al contents were lower with P application than those without P application. Further, Al accumulation was higher in the roots, but lower in the shoots and leaves of G9 than in those of DH32-29. The secretion of organic acids was higher under Al stress than under no Al stress. Further, under Al stress, the roots of G9 secreted more organic acids than those of DH32-29. With an increase in P supply, Al-induced secretion of organic acids from roots decreased. Under Al stress, some enzymes, including PEPC, CS, and IDH, played important roles in organic acid biosynthesis and degradation. Thus, our results indicate that P can reduce Al toxicity via the fixation of elemental Al in roots and restriction of its transport to stems and leaves, although P application cannot promote the secretion of organic acid anions. Further, the higher Al-resistance of G9 might be attributed to the higher Al accumulation in and organic acid anion secretion from roots and the lower levels of Al in leaves. PMID:29324770

Chemical signature of a migrating grain boundaries in polycrystalline olivine

NASA Astrophysics Data System (ADS)

Boneh, Y.; Marquardt, K.; Skemer, P. A.

2017-12-01

Olivine is the most abundant phase and influences strongly the physical and chemical properties of the upper mantle. The structure and chemistry of olivine grain-boundaries is important to understand, as these interfaces provide a reservoir for incompatible elements and partial melt, and serve as a fast pathway for chemical diffusion. This project investigates the chemical characteristics of grain boundaries in an olivine-rich aggregate. The sample is composed of Fo50 olivine crystals with minor amounts of enstatite. It was previously deformed (Hansen et al., 2016) and then annealed (Boneh et al., 2017) to investigate the microstructural changes during recrystallization. This transient microstructure has a bimodal grain size distribution and includes grains that experienced abnormal grain-growth, (porphyroblasts) and highly strained grains with no significant recrystallization or growth (matrix). Using high-resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray (EDX) at the Bayerisches Geoinstitut (BGI), we characterized boundaries between pairs of porphyroblasts, pairs of matrix grains, and mixed boundaries between porphyroblast and matrix grains. It was found that the boundary between porphyroblasts is enriched in Al and Ca and depleted in Mg, in comparison to grain interiors. However, matrix-matrix boundaries show less chemical segregation of these elements. The relatively high level of chemical segregation to porphyroblast grain boundaries offers different possible interpretations: 1) During grain boundary migration incompatible elements are swept up by the migrating grain boundary. 2) Large angle grain boundaries provide a large density of energetically favorable storage sites for incompatible elements. 3) Diffusion along low angle grain boundaries is too slow to allow for fast chemical equilibration between the different grain boundaries. 4) Dislocations cores serve as an important transport media for impurities (i.e., Cottrell atmosphere). We will further discuss these different interpretations, their feasibility, and implications for the geochemistry of the mantle.

Multiple populations in more metal-rich galactic globular clusters

NASA Astrophysics Data System (ADS)

Cordero, Maria J.

In this thesis we present chemical abundances for bright stars in the intermediate metallicity globular cluster (GC) M5, and the relatively metal-rich GCs M71 and 47 Tuc with the goal of improving the understanding of chemical evolution in the metallicity regime sampled by these three GCs. The first chapter presents a brief historical overview in light element abundance variations in globular clusters. In the second chapter we present the results obtained for 47 Tuc, the most-metal rich cluster of my sample. 47 Tuc is an ideal target to study chemical evolution and GC formation in massive more metal-rich GCs since it is the closest massive GC. Chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu were determined for 164 red giant branch (RGB) stars in 47 Tuc using spectra obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m telescope and the FLAMES multi-object spectrograph at the ESO Very Large Telescope. The average [Fe/H]= --0.79+/-0.09 dex is consistent with literature values, as well as over-abundances of alpha-elements ([alpha/Fe] ~ 0.3 dex). The n-capture process elements indicate that 47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature typically seen in Galactic GCs, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] ~ --0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A KS-test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of AGB nucleosynthesis yields. Aluminum is the heaviest light element displaying large star-to-star variations in Galactic GCs. This element may provide additional insight into the origin of the multiple populations and the nature of the first-generation stars responsible for chemical inhomogeneities. We found that, unlike more metal-poor GCs, 47 Tuc did not exhibit a strong Na-Al correlation, which motivates a careful study of the similar metallicity but less massive GC M71. In chapter 3, we present chemical abundances of O, Na, Al, and Fe for 33 giants in M71 using spectra obtained with the WIYN-Hydra spectrograph. Our spectroscopic analysis finds that, similar to 47 Tuc and in contrast with more metal-poor GCs, M71 stars do not exhibit a strong Na-Al correlation and span a relatively narrow range in [Al/Fe]. Furthermore, these data suggest that only a small fraction of stars (29%) have an [Na/Fe] ratio similar to halo stars at this metallicity, which is a characteristic reproduced by GC formation and evolution models. In the fourth chapter we present chemical abundances for a sample of 61 red giants in the intermediate-metallicity GC M5. The data were obtained using the Hydra multi-fiber positioner and bench spectrograph on the WIYN telescope. We find that our abundance ratios for Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu agree with published values for this cluster. The scatter seen in Fe-peak, alpha, and neutron-capture elements is consistent with typical spectroscopic errors. However, we identified a star modestly enhanced in La by performing a careful comparison of stellar spectra with similar atmospheric parameters. La-enhanced stars are rare in GCs. For instance, we have found only one such star in each of M5 and 47 Tuc. M5 red giants exhibit a strong Na-Al correlation, which is absent in M71 and 47 Tuc. Furthermore, M5 is at the metallicity regime where GCs seem to transition from small to large [Al/Fe] scatter. Interestingly, this metallicity regime also separates metal-poor from metal-rich Galactic GCs. In the fifth chapter we present radial distributions, population fractions, detailed examination of behavior of Al in more metal-rich GCs in the context of cluster chemical evolution, and, finally, a kinematical study of the GC M13 using spectra acquired with the WIYN-Hydra spectrograph. We find a rotational signal and a kinematical difference between the intermediate and extreme generations. Specifically, we find that the extreme O-depleted population, which is also more centrally concentrated than the primordial and intermediate populations, has the highest rotational amplitude. (Abstract shortened by UMI.)

Defect investigations of micron sized precipitates in Al alloys

NASA Astrophysics Data System (ADS)

Klobes, B.; Korff, B.; Balarisi, O.; Eich, P.; Haaks, M.; Kohlbach, I.; Maier, K.; Sottong, R.; Staab, T. E. M.

2011-01-01

A lot of light aluminium alloys achieve their favourable mechanical properties, especially their high strength, due to precipitation of alloying elements. This class of age hardenable Al alloys includes technologically important systems such as e.g. Al-Mg-Si or Al-Cu. During ageing different precipitates are formed according to a specific precipitation sequence, which is always directed onto the corresponding intermetallic equilibrium phase. Probing the defect state of individual precipitates requires high spatial resolution as well as high chemical sensitivity. Both can be achieved using the finely focused positron beam provided by the Bonn Positron Microprobe (BPM) [1] in combination with the High Momentum Analysis (HMA) [2]. Employing the BPM, structures in the micron range can be probed by means of the spectroscopy of the Doppler broadening of annihilation radiation (DBAR). On the basis of these prerequisites single precipitates of intermetallic phases in Al-Mg-Si and Al-Cu, i.e. Mg2Si and Al2Cu, were probed. A detailed interpretation of these measurements necessarily relies on theoretical calculations of the DBAR of possible annihilation sites. These were performed employing the DOPPLER program. However, previous to the DBAR calculation the structures, which partly contain vacancies, were relaxed using the ab-initio code SIESTA, i.e. the atomic positions in presence of a vacancy were recalculated.

Deformation behaviour of Rheocast A356 Al alloy at microlevel considering approximated RVEs

NASA Astrophysics Data System (ADS)

Islam, Sk. Tanbir; Das, Prosenjit; Das, Santanu

2015-03-01

A micromechanical approach is considered here to predict the deformation behaviour of Rheocast A356 (Al-Si-Mg) alloy. Two representative volume elements (RVEs) are modelled in the finite element (FE) framework. Two dimensional approximated microstructures are generated assuming elliptic grains, based on the grain size, shape factor and area fraction of the primary Al phase of the said alloy at different processing condition. Plastic instability is shown using stress and strain distribution between the Al rich primary and Si rich eutectic phases under different boundary conditions. Boundary conditions are applied on the approximated RVEs in such a manner, so that they represent the real life situation depending on their position on a cylindrical tensile test sample. FE analysis is carried out using commercial finite element code ABAQUS without specifying any damage or failure criteria. Micro-level in-homogeneity leads to incompatible deformation between the constituent phases of the rheocast alloy and steers plastic strain localisation. Plastic stain localised regions within the RVEs are predicted as the favourable sites for void nucleation. Subsequent growth of nucleated voids leads to final failure of the materials under investigation.

Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

DOE PAGES

Wang, Lin -Lin; Herwadkar, Aditi; Reich, Jason M.; ...

2016-08-18

Here, alane (AlH 3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H 2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H 2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H 2 exposure, alanemore » monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH 3 or closely related species at 344 bar H 2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.« less

EXPLORING ANTICORRELATIONS AND LIGHT ELEMENT VARIATIONS IN NORTHERN GLOBULAR CLUSTERS OBSERVED BY THE APOGEE SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C–N and Mg–Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two mostmore » metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that {sup 28}Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.« less

Exploring Anticorrelations and Light Element Variations in Northern Globular Clusters Observed by the APOGEE Survey

NASA Astrophysics Data System (ADS)

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew; Lucatello, Sara; Troup, Nicholas W.; Bovy, Jo; Cunha, Katia; García-Hernández, Domingo A.; Overbeek, Jamie C.; Allende Prieto, Carlos; Beers, Timothy C.; Frinchaboy, Peter M.; García Pérez, Ana E.; Hearty, Fred R.; Holtzman, Jon; Majewski, Steven R.; Nidever, David L.; Schiavon, Ricardo P.; Schneider, Donald P.; Sobeck, Jennifer S.; Smith, Verne V.; Zamora, Olga; Zasowski, Gail

2015-05-01

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C-N and Mg-Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two most metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that 28Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.

Superconductivity up to 114 K in the Bi-Al-Ca-Sr-Cu-O compound system without rare-earth elements

NASA Technical Reports Server (NTRS)

Chu, C. W.; Bechtold, J.; Gao, L.; Hor, P. H.; Huang, Z. J.

1988-01-01

Stable superconductivity up to 114 K has been reproducibly detected in Bi-Al-Ca-Sr-Cu-O multiphase systems without any rare-earth elements. Pressure has only a slight positive effect on T(c). These observations provide an extra material base for the study of the mechanism of high-temperature superconductivity and also the prospect of reduced material cost for future applications of superconductivity.

Growth Structure and Properties of Gradient Nanocrystalline Coatings of the Ti-Al-Si-Cu-N System

NASA Astrophysics Data System (ADS)

Ovchinnikov, S. V.; Pinzhin, Yu. P.

2016-10-01

Methods of electron microprobe analysis, X-ray structure analysis and electron microscopy were used to study the element composition and features of the structure-phase, elastic stress state of nanocrystalline coatings of the Ti- Al- Si- Cu- N system with gradient of copper concentration across their thickness. The authors established the effects of element composition modification, non-monotonous behavior of the lattice constant of alloyed nitride and rise in the bending-torsion value of the crystalline lattice in individual nanocrystals to values of around 400 degrees/μm with increase in copper concentration, whereas the sizes of alloyed nitride crystals remained practically unchanged. Mechanical (hardness), adhesion and tribological properties of coatings were examined. Comparative analysis demonstrates higher values of adhesion characteristics in the case of gradient coatings of the Ti- Al- Si- Cu- N system than in the case of single-layer (with constant element concentration) analogues.

Minor elements in magnetic concentrates from the Syenite-Shonkinite Province, southern Asir, Kingdom of Saudi Arabia

USGS Publications Warehouse

Overstreet, W.C.; Day, G.W.; Botinelly, Theodore; VanTrump, George

1987-01-01

Magnetic concentrates from 106 localities in three plutons of syenite and one pluton of shonkinite in the southern Asir were analyzed spectrographically for 31 elements to determine if anomaly-enhancement techniques would identify mineralization not disclosed by conventional geochemical sample media. Positive anomalies are lacking for all elements except vanadium. Vanadium contents as high as 0.7 percent were identified in magnetic concentrates from the syenite pluton to the southeast of Suq al Ithnayn, but magnetite is sparse. This observation indicates a need to reexamine magnetite-rich drill core for possible ore-grade tenors in vanadium from the zoned pluton at Lakathah. Experimental analyses for platinum-group metals in magnetic concentrates from layered mafic plutons at Jabal Sha'i', Jabal al Ashshar, and Hishshat al Hawi should be performed to determine whether micron-size particles of the platinum-group metals are present in mafic rocks of the Arabian Shield.

The Effect of Hydrogen Annealing on the Impurity Content of Alumina-Forming Alloys

NASA Technical Reports Server (NTRS)

Smialek, James L.

2000-01-01

Previously, the effect of hydrogen annealing on increasing the adhesion of Al2O3 scales had been related to the effective desulfurization that occurred during this process. The simultaneous reduction of other impurities has now been re-examined for up to 20 impurity elements in the case of five different alloys (NiCrAl, FeCrAl, PWA 1480, Rene'142, and Rene'N5). Hydrogen annealing produced measurable reductions in elemental concentration for B, C, Na, Mg, P, K, Sr, or Sn in varying degrees for at least one and up to three of these alloys. No single element was reduced by hydrogen annealing for all the alloys except sulfur. In many cases spalling occurred at low levels of these other impurities, while in other cases the scales were adherent at high levels of the impurities. No impurity besides sulfur was strongly correlated with adhesion.

Asteroid orbital error analysis: Theory and application

NASA Technical Reports Server (NTRS)

Muinonen, K.; Bowell, Edward

1992-01-01

We present a rigorous Bayesian theory for asteroid orbital error estimation in which the probability density of the orbital elements is derived from the noise statistics of the observations. For Gaussian noise in a linearized approximation the probability density is also Gaussian, and the errors of the orbital elements at a given epoch are fully described by the covariance matrix. The law of error propagation can then be applied to calculate past and future positional uncertainty ellipsoids (Cappellari et al. 1976, Yeomans et al. 1987, Whipple et al. 1991). To our knowledge, this is the first time a Bayesian approach has been formulated for orbital element estimation. In contrast to the classical Fisherian school of statistics, the Bayesian school allows a priori information to be formally present in the final estimation. However, Bayesian estimation does give the same results as Fisherian estimation when no priori information is assumed (Lehtinen 1988, and reference therein).

Trace element and petrologic clues to the formation of forsterite-bearing Ca-Al-rich inclusions in the Allende meteorite

NASA Astrophysics Data System (ADS)

Wark, D. A.; Boynton, W. V.; Keays, R. R.; Palme, H.

1987-03-01

This work presents new trace element and petrographic data for three forsterite-bearing, Ca-Al-rich inclusions from the Allende meteorite: TE, 818a, and 110-A. Such inclusions form a continuum with Type B1 and B2 Ca-Al-rich inclusions (CAIs), and the authors refer to them as "Type B3" CAIs. Textures, mineral chemistries, crystal-chemically fractionated REE patterns, and other properties suggest that Type B3 crystallized from partly molten evaporative residues. They also present evidence that 818a was strongly re-heated and modified in the nebula after its initial crystallization: it consists of a core of coarse-grained Ti-Al-pyroxene (Tpx), forsterite, spinel and metal grains and a thick, surrounding mantle of melilite.

Pyrometallurgical Extraction of Valuable Elements in Ni-Metal Hydride Battery Electrode Materials

NASA Astrophysics Data System (ADS)

Jiang, Yin-ju; Deng, Yong-chun; Bu, Wen-gang

2015-10-01

Gas selective reduction-oxidation (redox) and melting separation were consecutively applied to electrode materials of AB5-type Ni-metal hydride batteries leading to the production of a Ni-Co alloy and slag enriched with rare earth oxides (REO). In the selective redox process, electrode materials were treated with H2/H2O at 1073 K and 1173 K (800 °C and 900 °C). Active elements such as REs, Al, and Mn were oxidized whereas relatively inert elements such as Ni and Co were transformed into their elemental states in the treated materials. SiO2 and Al2O3 powders were added into the treated materials as fluxes which were then melted at 1823 K (1550 °C) to yield a Ni-Co alloy and a REO-SiO2-Al2O3-MnO slag. The high-purity Ni-Co alloy produced can be used as a raw material for AB5-type hydrogen-storage alloy. The REO content in slag was very high, i.e., 48.51 pct, therefore it can be used to recycle rare earth oxides.

Arsenic and mercury contamination related to historical goldmining in the Sierra Nevada, California

USGS Publications Warehouse

Alpers, Charles N.

2017-01-01

Arsenic (As) is a naturally occurring constituent in low-sulphide gold-quartz vein deposits, the dominant deposit type for lode mines in the Sierra Nevada Foothills (SNFH) gold (Au) province of California. Concentrations of naturally occurring mercury (Hg) in the SNFH Au province are low, but extensive use and loss of elemental Hg during amalgamation processing of ore from lode and placer Au deposits led to widespread contamination of Hg in the Sierra Nevada foothills and downstream areas, such as the Sacramento–San Joaquin Delta and San Francisco Bay. This review paper provides an overview of As and Hg contamination related to historical Au mining in the Sierra Nevada of California. It summarizes the geology, mineralogy, and geochemistry of the Au deposits, and provides information on specific areas where detailed studies have been done in association with past, ongoing, and planned remediation activities related to the environmental As and Hg contamination.Arsenic is a naturally occurring constituent in low-sulphide Au-quartz vein deposits, the dominant deposit type for lode mines in the Sierra Nevada Foothills (SNFH) Au province (Ashley 2002). Because of elevated concentrations of As in accessory iron-sulphide minerals including arsenopyrite (FeAsS) and arsenian pyrite (Fe(S,As)2), As is commonly a contaminant of concern in lode Au mine waste, including waste rock and mill tailings. The principal pathways of human As exposure from mine waste include ingestion of soil or drinking water, and inhalation of dust in contaminated areas (Mitchell 2014).Concentrations of naturally occurring Hg in the SNFH Au province are low, but extensive use and loss of elemental Hg during amalgamation processing of ore from lode and placer Au deposits (Churchill 2000) led to widespread contamination of Hg in the Sierra Nevada foothills and downstream areas, such as the Sacramento–San Joaquin Delta and San Francisco Bay (Alpers et al. 2005a). Conversion of Hg to monomethylmercury (MeHg) by sulphate-reducing and iron-reducing microbes facilitates its bioaccumulation (Wiener et al. 2003). The human Hg exposure pathway of main concern is ingestion of MeHg from sport (non-commercial) fish, especially higher trophic levels such as bass species (Davis et al. 2008). Wildlife exposure to MeHg is also a concern because of chronic and reproductive effects, for example in fish-eating and invertebrate-foraging birds (e.g. Wiener et al. 2003; Eagles-Smith et al. 2009; Ackerman et al. 2016).

An Experimental Investigation of Effects of Fluxes (Na3AlF6 and K2TiF6), Element Alloys (Mg), and Composite Powders ((Al + TiC)CP and (Al + B4C)CP) on Distribution of Particles and Phases in Al-B4C and Al-TiC Composites

NASA Astrophysics Data System (ADS)

Mazaheri, Younes; Emadi, Rahmatollah; Meratian, Mahmood; Zarchi, Mehdi Karimi

2017-04-01

The wettability, incorporation, and gravity segregation of TiC and B4C particles into molten aluminum are important problems in the production of Al-TiC and Al-B4C composites by the casting techniques. In order to solve these problems, different methods consisting of adding the Na3AlF6 and K2TiF6 fluxes and Mg (as the alloying element) into the molten aluminum and injection of the (Al + TiC)CP and (Al + B4C)CP composite powders instead of B4C and TiC particles are evaluated. In this work, the conditions of sample preparation, such as particle addition temperature, stirring speed, and stirring time, are determined after many studies and tests. Microstructural characterizations of samples are investigated by scanning electron microscopy equipped with energy dispersive spectroscopy (EDS) and X-ray diffractometry. The results show better distribution and incorporation of TiCp and B4Cp in aluminum matrix when the fluxes are used, as well as EDS analysis of the interface between the matrix and reinforcement-strengthened formation of the different phases such as Al4C3 in the Al-TiC composites and Al3BC, TiB2 in the Al-B4C composites.

Evolution of trace elements in the planetary boundary layer in southern China: Effects of dust storms and aerosol-cloud interactions

NASA Astrophysics Data System (ADS)

Li, Tao; Wang, Yan; Zhou, Jie; Wang, Tao; Ding, Aijun; Nie, Wei; Xue, Likun; Wang, Xinfeng; Wang, Wenxing

2017-03-01

Aerosols and cloud water were analyzed at a mountaintop in the planetary boundary layer in southern China during March-May 2009, when two Asian dust storms occurred, to investigate the effects of aerosol-cloud interactions (ACIs) on chemical evolution of atmospheric trace elements. Fe, Al, and Zn predominated in both coarse and fine aerosols, followed by high concentrations of toxic Pb, As, and Cd. Most of these aerosol trace elements, which were affected by dust storms, exhibited various increases in concentrations but consistent decreases in solubility. Zn, Fe, Al, and Pb were the most abundant trace elements in cloud water. The trace element concentrations exhibited logarithmic inverse relationships with the cloud liquid water content and were found highly pH dependent with minimum concentrations at the threshold of pH 5.0. The calculation of Visual MINTEQ model showed that 80.7-96.3% of Fe(II), Zn(II), Pb(II), and Cu(II) existed in divalent free ions, while 71.7% of Fe(III) and 71.5% of Al(III) were complexed by oxalate and fluoride, respectively. ACIs could markedly change the speciation distributions of trace elements in cloud water by pH modification. The in-cloud scavenging of aerosol trace elements likely reached a peak after the first 2-3 h of cloud processing, with scavenging ratios between 0.12 for Cr and 0.57 for Pb. The increases of the trace element solubility (4-33%) were determined in both in-cloud aerosols and postcloud aerosols. These results indicated the significant importance of aerosol-cloud interactions to the evolution of trace elements during the first several cloud condensation/evaporation cycles.

Allergic reaction to vanadium causes a diffuse eczematous eruption and titanium alloy orthopedic implant failure.

PubMed

Engelhart, Sally; Segal, Robert J

2017-04-01

Allergy as a cause of adverse outcomes in patients with implanted orthopedic hardware is controversial. Allergy to titanium-based implants has not been well researched, as titanium is traditionally thought to be inert. We highlight the case of a patient who developed systemic dermatitis and implant failure after surgical placement of a titanium alloy (Ti6Al4V) plate in the left foot. The hardware was removed and the eruption cleared in the following weeks. The plate and screws were submitted for metal analysis. The elemental composition of both the plate and screws included 3 major elements-titanium, aluminum, and vanadium-as well as trace elements. Metal analysis revealed that the plate and screws had different microstructures, and electrochemical studies demonstrated that galvanic corrosion could have occurred between the plate and screws due to their different microstructures, contributing to the release of vanadium in vivo. The patient was patch tested with several metals including components of the implant and had a positive patch test reaction only to vanadium trichloride. These findings support a diagnosis of vanadium allergy and suggests that clinicians should consider including vanadium when patch testing patients with a suspected allergic reaction to vanadium-containing implants.

[Distribution Characteristics, Sources and Pollution Assessment of Trace Elements in Surficial Sediments of the Coastal Wetlands, Northeastern Hainan Island].

PubMed

Zhang, Wei-kun; Gan, Hua-yang; Bi, Xiang-yang; Wang, Jia-sheng

2016-04-15

Totally 128 surficial sediments samples were collected from the coastal wetlands, northeastern Hainan Island and analyzed for their concentrations of 14 elements including Al2O3, Fe2O3, MnO, Cu, Ni, Sr, Zn, V, Pb, Cr, Zr, As, Cd and Hg, TOC and grain sizes. The mean concentrations of trace metals V, Cr, Ni, Cu, Zn, As, Pb, Cd and Hg were (40.13 +/- 32.65), (35.92 +/- 26.90), (13.03 +/- 11.46), (11.56 +/- 10.27)-, (48.75 +/- 27.00), (5.48 +/- 1.60), ( 18.70 +/- 8.66), (0.054 +/- 0.045 ), (0.050 +/- 0.050) microg x g(-1), respectively, which were much lower than those in Pearl River Estuary, Yangzi River Estuary, Bohai Bay, upper crust and average shale. The average concentrations of Sr and Zr were much higher, reaching up to (1253.60 +/- 1649.58) microg x g(-1) and (372.40 +/- 516.49) microg x g(-1), respectively. The spatial distribution patterns of Al2O3, Fe2O3, MnO, Cu, Ni, Zn, V, Pb, Cr, Cd and Hg concentrations were the same as each other except for those of As, Sr and Zr. Generally, relatively high concentrations of these elements only appeared in the Haikou Bay, Nandu estuary, Dongzhai Harbor, Qinglan Harbor and Xiaohai in study area. The factor analysis revealed that the trace elements Al2O3 Fe2O3, MnO, Cu, Ni, Zn, V, Pb, Cr and part of Hg were mainly originated from the rock material by natural weathering processes, while the Cd and a part of Hg were from the biological source controlled by TOC. As and part of MnO were influenced by anthropogenic source, especially by aquacultures. Zr and some MnO were derived from heavy minerals dominated by the coarse grain of sediments. In contrast to the ERL, ERM and the results of enrichment factors (EF) , the environment of study area was good in general and the degree of contamination by trace elements was low on the whole. However, there are still some places where anthropogenic input have caused serious enrichments of trace elements and the occasional adverse effect on benthic organism induced by Ni could probably occur in 22% areas of all the sampling stations.

Comparative effect of Al, Se, and Mo toxicity on NO3(-) assimilation in sunflower (Helianthus annuus L.) plants.

PubMed

Ruiz, Juan M; Rivero, Rosa M; Romero, Luis

2007-04-01

Here, we study the effect caused by three trace elements--Al, Se, and Mo--applied at the same concentration (100 microM) and in their oxyanionic forms--NaAl(OH)(4), Na(2)SeO(4), and Na(2)MoO(4)--on NO(3)(-) assimilation (NO(3)(-), nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) activities, and concentrations of amino acids and proteins) in sunflower (Helianthus annuus L. var. Kasol) plants. The most harmful element for sunflower plants proved to be selenate, followed by aluminate. On the contrary, the application of molybdate had no negative effect on the growth of this plant, suggesting the possibility of using sunflower for the phytoremediation of this metal, mainly in agricultural zones used for grazing where the excess of this element can provoke problems of molybdenosis in ruminants (particularly in cattle). In addition, we found that the alteration of NO(3)(-) assimilation by SeO(4)(2-) and Al(OH)(4)(-) directly influences the growth and development of plants, foliar inhibition of NR activity by SeO(4)(2-) being more harmful than the decrease in foliar availability of NO(3)(-) provoked by Al(OH)(4)(-).

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Correlations between elements in the fur of wild animals.

PubMed

Długaszek, Maria; Kopczyński, Krzysztof

2014-07-01

There is little data on the elemental composition of wild animals fur. In the paper, an attempt has been made to evaluate the concentration of elements in the fur of roe deer, wild boar and hare. The contents of following elements: calcium (Ca), magnesium (Mg), zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), cadmium (Cd), aluminium (Al), chromium (Cr), nickel (Ni) were determined by atomic absorption spectrometry method. Their content was in the range 0.01 (Cd) to 1,519 (Ca) μg/g. Correlations between the content of Mn, Al, Ca, Pb, Cr, Ni in the fur of animals, liver and muscle tissues were found. Thus it can be assumed that the fur of wild animals can provide an information on the bioavailability of elements and environmental exposure and can be considered as an useful biomarker in animals and environmental studies, although research on this subject should be continued.

Nanogeochemistry of hydrothermal magnetite

NASA Astrophysics Data System (ADS)

Deditius, Artur P.; Reich, Martin; Simon, Adam C.; Suvorova, Alexandra; Knipping, Jaayke; Roberts, Malcolm P.; Rubanov, Sergey; Dodd, Aaron; Saunders, Martin

2018-06-01

Magnetite from hydrothermal ore deposits can contain up to tens of thousands of parts per million (ppm) of elements such as Ti, Si, V, Al, Ca, Mg, Na, which tend to either structurally incorporate into growth and sector zones or form mineral micro- to nano-sized particles. Here, we report micro- to nano-structural and chemical data of hydrothermal magnetite from the Los Colorados iron oxide-apatite deposit in Chile, where magnetite displays both types of trace element incorporation. Three generations of magnetites (X-Z) were identified with concentrations of minor and trace elements that vary significantly: SiO2, from below detection limit (bdl) to 3.1 wt%; Al2O3, 0.3-2.3 wt%; CaO, bdl-0.9 wt%; MgO, 0.02-2.5 wt%; TiO2, 0.1-0.4 wt%; MnO, 0.04-0.2 wt%; Na2O, bdl-0.4 wt%; and K2O, bdl-0.4 wt%. An exception is V2O3, which is remarkably constant, ranging from 0.3 to 0.4 wt%. Six types of crystalline nanoparticles (NPs) were identified by means of transmission electron microscopy in the trace element-rich zones, which are each a few micrometres wide: (1) diopside, (2) clinoenstatite; (3) amphibole, (4) mica, (5) ulvöspinel, and (6) Ti-rich magnetite. In addition, Al-rich nanodomains, which contain 2-3 wt% of Al, occur within a single crystal of magnetite. The accumulation of NPs in the trace element-rich zones suggest that they form owing to supersaturation from a hydrothermal fluid, followed by entrapment during continuous growth of the magnetite surface. It is also concluded that mineral NPs promote exsolution of new phases from the mineral host, otherwise preserved as structurally bound trace elements. The presence of abundant mineral NPs in magnetite points to a complex incorporation of trace elements during growth, and provides a cautionary note on the interpretation of micron-scale chemical data of magnetite.

Geochemical properties of topsoil around the coal mine and thermoelectric power plant.

PubMed

Stafilov, Trajče; Šajn, Robert; Arapčeska, Mila; Kungulovski, Ivan; Alijagić, Jasminka

2018-03-19

The results of the systematic study of the spatial distribution of trace metals in surface soil over the Bitola region, Republic of Macedonia, known for its coal mine and thermo-electrical power plant activities are reported. The investigated region (3200 km 2 ) is covered by a sparse sampling grid of 5 × 5 km, but in the urban zone and around the thermoelectric power plant the sampling grid is denser (1 × 1 km). In total, 229 soil samples from 149 locations were collected including top-soil (0-5 cm) and bottom-soil samples (20-30 cm and 0-30 cm). Inductively coupled plasma - atomic emission spectrometry (ICP-AES) was applied for the determinations of 21 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V and Zn). Based on the results of factor analyses, three geogenic associations of elements have been defined: F1 (Fe, Ni, V, Co, Cr, Mn and Li), F2 (Zn, B, Cu, Cd, Na and K) and F3 (Ca, Sr, Mg, Ba and Al). Even typical trace metals such as As, Cd, Cu, Ni, P, Pb and Zn are not isolated into anthropogenic geochemical associations by multivariate statistical methods still show some trends of local anthropogenic enrichment. The distribution maps for each analyzed element is showing the higher content of these elements in soil samples collected around the thermoelectric power plants than their average content for the soil samples collected from the whole Bitola Region. It was found that this enrichment is a result of the pollution by fly ash from coal burning which deposited near the plant having a high content of these elements.

Elemental Composition of 433 Eros: New Calibration of the NEAR-Shoemaker XRS Data

NASA Technical Reports Server (NTRS)

Lim, Lucy F.; Nittler, Larry R.

2009-01-01

We present a new calibration of the elemental-abundance data for Asteroid 433 Fros taken by the X-ray spectrometer (XRS) aboard the NEAR-Shoemaker spacecraft. (NEAR is an acronym for "Near-Earth Asteroid Rendezvous,") Quintification of the asteroid surface elemental abundance ratios depends critically on accurate knowledge of the incident solar X-ray spectrum, which was monitored simultaneously with asteroid observations. Previously published results suffered from incompletely characterized systematic uncertainties due to an imperfect ground calibrations of the NEAR gas solar monitor. The solar monitor response function and associated uncertainties have now been characterized by cross-calibration of a large sample of NEAR solar monitor flight data against. contemporary broadband solar X-ray data from the Earth-orbiting GOES-8 (Geostationary Operational Environmental Satellite). The results have been used to analyze XRS spectra acquired from Eros during eight major solar flares (including three that have not previously been reported). The end product of this analysis is a revised set of Eros surface elemental abundance ratios with new error estimates that more accurately reflect the remaining uncertainties in the solar flare spectra: Mg/Si=.753 +0.078/-0.055, Al/Si=0.069 +/-0.055, S/Si=0.005+/-0.008, Ca/Si=0.060+0.023/-0.024, and Fe/Si= 1.578+0.338/-0.320. These revised abundance ratios are consitent within cited uncertainties with the results of Nittler et al. [Nittler, L.R., and 14 colleagues, 2001. Meteorit Planet. Sci 36, 1673-1695] and thus support the prior conclusions that 433 Eros has major-element composition simular to ordinary chondrites with the exception of a stong depletoin in sulfur, most likely caused by space weathering.

Fluorescent lighting with aluminum nitride phosphors

DOEpatents

Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

2016-05-10

A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

Investigation of major and trace element distribution in the extraction-transesterification process of fatty acid methyl esters from microalgae Chlorella sp.

PubMed

Soares, Bruno M; Vieira, Augusto A; Lemões, Juliana S; Santos, Clarissa M M; Mesko, Márcia F; Primel, Ednei G; Montes D'Oca, Marcelo G; Duarte, Fábio A

2012-04-01

This work reports, for the first time, the determination of major and trace elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Se, Sn, Sr, Ti, Tl, U, V, and Zn) in the fractions of the synthesis of fatty acid methyl esters (FAMEs). These include fresh microalgae, residual biomass, lipid fraction, crude FAMEs, insoluble fraction and purified FAMEs from microalgae Chlorella sp. A microwave-assisted digestion procedure in closed vessels was applied for sample digestion and subsequent element determination by inductively coupled plasma-based techniques. The proposed method was suitable for the multielement determination in FAMEs and its fractions obtained from microalgae. The element concentration was compared with results found in the literature and a careful discussion about the use of residual biomass for different applications was performed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of Santa Catarina (Brazil) coal with respect to human health and environmental concerns

USGS Publications Warehouse

Silva, L.F.O.; Oliveira, M.L.S.; Boit, K.M.; Finkelman, R.B.

2009-01-01

The current paper presents the concentration, distribution, and modes of occurrence of trace elements of 13 coals from south Brazil. The samples were collected in the state of Santa Catarina. Chemical analyses and the high ash yields indicate that all studied coals are rich in mineral matter, with SiO2 and Al2O3 dominating as determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Quartz is the main mineral species and is associated with minor levels of feldspars, kaolinite, hematite, and iron-rich carbonates. The contents of trace elements, including As, Pb, Cd, Ni, Cr, Mn, Be, V, U, Zn, Li, Cu, Tl, and Ni, in coals were determined. A comparison of ranges and means of elemental concentrations in Santa Catarina, Brazil, and world coals shows that the ranges of most elements in Santa Catarina coal are very close to the usual worldwide concentration ranges in coal. ?? Springer Science+Business Media B.V. 2008.

Face-Centred Cubic Iron: Ab Initio Calculations of Sound Velocities in the Lunar Core

NASA Astrophysics Data System (ADS)

Wood, M. C.; Wood, I. G.; Vočadlo, L.

2017-12-01

Studies, such as the reanalysis of the Apollo lunar seismograms [1], have shown that the Moon has undergone differentiation and possesses a small core. The composition of the lunar core is not well constrained, and many compositional models have been suggested including combinations of iron, nickel, and light elements such as sulphur and carbon [e.g. 1, 2, 3, 4], and other more exotic compositions [5]. Additional constraints are crucial to our understanding of the Moon, including its formation, the dynamics of its interior, and a lunar dynamo. We use ab initio molecular dynamics simulations to calculate elastic constants of face-centred cubic (fcc) iron and iron alloys and hence sound velocities at lunar core conditions, at 5-6 GPa and 1,300-1,900 K [3]. The results from these simulations will then be compared with the data from the Apollo seismograms and experimental data to help form a description of the lunar interior. [1] Weber et al. (2011) Science 331, 309-312. [2] Dasgupta et al. (2009) Geochim. Cosmochim. Acta 73, 6678-6692. [3] Antonangeli et al. (2015) Proc. Natl. Acad. Sci. U.S.A. 112, 3916-3919. [4] Righter et al. (2017) Earth Planet. Sci. Lett. 463, 323-332. [5] Wieczorek & Zuber (2002) Lunar Planet. Sci. 33, abstract 1384.

26Al-containing acidic and basic sodium aluminum phosphate preparation and use in studies of oral aluminum bioavailability from foods utilizing 26Al as an aluminum tracer

NASA Astrophysics Data System (ADS)

Yokel, Robert A.; Urbas, Aaron A.; Lodder, Robert A.; Selegue, John P.; Florence, Rebecca L.

2005-04-01

We synthesized 26Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down (∼3000- and 850-fold) to prepare ∼300-400 mg of each SALP. The 26Al was incorporated at the beginning of the syntheses to maximize 26Al and 27Al equilibration and incorporate the 26Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used to characterize the two SALP samples and some intermediate samples. Multi-elemental analysis (MEA) was used to determine Na, Al and P content. Commercial products were included for comparison. Satisfactory XRD analyses, near infrared spectra and MEA results confirmed that we synthesized acidic and basic SALP, as well as some of the syntheses intermediates. The 26Al-containing acidic and basic SALPs were incorporated into a biscuit material and a processed cheese, respectively. These were used in oral bioavailability studies conducted in rats in which the 26Al present in blood after its oral absorption was quantified by accelerator mass spectrometry. The results showed oral Al bioavailability from acidic SALP in biscuit was ∼0.02% and from basic SALP in cheese ∼0.05%, lower than our previous determination of Al bioavailability from drinking water, ∼0.3%. Both food and water can appreciably contribute to the Al absorbed from typical human Al intake.

Investigation into MIS 11 in the U.S. Great Basin Using Trace Elements and Stable Isotopes from two Lehman Caves Stalagmites

NASA Astrophysics Data System (ADS)

Neary, A.; McGee, D.; Tal, I.; Shakun, J. D.

2015-12-01

Marine Isotope Stage 11 (MIS 11) represents a long interglacial period of high temperatures and muted orbital variability that occurred around 424-374 kya, and is referred to as a 'super-interglacial'. MIS 11 is marked by especially pronounced high latitude warming in the Northern Hemisphere from 410-400 ka and thus presents a natural experiment for investigating the response of Great Basin precipitation to high latitude temperatures.MIS 11 is recorded by stalagmites LC3 and BT1 from Lehman Caves in Great Basin National Park, Nevada. LC3 represents 378-413 ka, while BT1 has a bottom age of 410 ka. Ongoing U-Th dating will refine chronologies from these samples. We will present stable isotope (δ13C and δ18O) and trace element (Mg/Ca and Sr/Ca) data from these stalagmites to study changes in precipitation recorded in them. Previous studies have shown a relationship between Mg/Ca, Sr/Ca, δ13C and prior calcite precipitation, and thus infiltration rates, in the cave system (Cross et al., 2015; Steponaitis et al., 2015). Meanwhile, δ18O has been shown to reflect larger scale atmospheric circulation.We will compare the records to previously published trace element and stable isotope data from more recent interglacials (Lachniet et al., 2014; Cross et al., 2015; Steponaitis et al., 2015) to test whether extensive high-latitude warming during MIS 11 was marked by anomalous precipitation patterns in the Great Basin. As they are coeval, we will also test the reproducibility between the stalagmites.References cited:Cross M., et al. (2015) Great Basin hydrology, paleoclimate, and connections with the North Atlantic: A speleothem stable isotope and trace element record from Lehman Caves, NV. Quaternary Science Reviews, in press.Steponaitis E., et al. (2015) Mid-Holocene drying the U.S. Great Basin recorded in Nevada speleothems. Quaternary Science Reviews, in press.Lachniet M. S., et al. (2014) Orbital control of western North America atmospheric circulation and climate over two glacial cycles. Nature Communications 5, 1-8.

The microstructure-processing-property relationships in an aluminum matrix composite system reinforced by aluminum-copper-iron alloy particles

NASA Astrophysics Data System (ADS)

Tang, Fei

Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of the matrix choice (elemental Al) and the "low shear" consolidation methods utilized. This reinforcement effectiveness is further evidenced by elastic modulus measurements of the composites that are very close to the upper bound predictions of the rule of mixtures. The load partitioning measurements by neutron diffraction showed that composite samples made from GARS powders present significantly higher load transfer efficiency than the composites made from commercially atomized powders. Further analysis of the load sharing measurements and the calculated values of the mismatch of coefficient of thermal expansion (CTE) and the geometrically necessary dislocation (GND) effects suggest that these strengthening mechanisms can be combined to predict accurately the strength of the composites. By neutron diffraction measurements, it also was found that the composites consolidated from Al and Al63Cu25Fe12 quasicrystal alloy reinforcement powders have compressive residual stress in the Al matrix, contrary to the tensile residual stress in typical Al/SiC composites. The composites made by the quasi-isostatic forging process exhibited higher tensile strengths and much higher compressive residual stresses than the composites made by the VHP process.

Assessment of elemental and NROM/TENORM hazard potential from non-nuclear industries in North Sinai, Egypt.

PubMed

El-Mekawy, A F; Badran, H M; Seddeek, M K; Sharshar, T; Elnimr, T

2015-09-01

Non-nuclear industries use raw materials containing significant levels of naturally occurring radioactive material (NORM). The processing of these materials may expose workers engaged in or even people living near such sites to technologically enhanced naturally occurring radioactive material (TENORM) above the natural background. Inductively coupled plasma and gamma ray spectrometry have been used to determine major and trace elements and radionuclide concentrations in various samples, respectively, in order to investigate the environmental impact of coal mining and cement plant in North Sinai, Egypt. Generally, very little attention was directed to the large volumes of waste generated by either type of industrial activities. Different samples were analyzed including various raw materials, coal, charcoal, Portland and white cement, sludge, and wastes. Coal mine and cement plant workers dealing with waste and kaolin, respectively, are subjected to a relatively high annual effective dose. One of the important finding is the enhancement of all measured elements and radionuclides in the sludge found in coal mine. It may pose an environmental threat because of its large volume and its use as combustion material. The mine environment may have constituted Al, Fe, Cr, and V pollution source for the local area. Higher concentration of Al, Fe, Mn, B, Co, Cr, Mn, Ni, Sr, V, and TENORM were found in Portland cement and Zn in white cement. Coal has higher concentrations of Al, Fe, B, Co, Cr, and V as well as (226)Ra and (232)Th. The compiled results from the present study and different worldwide investigations demonstrate the obvious unrealistic ranges normally used for (226)Ra and (232)Th activity concentrations in coal and provided ranges for coal, Portland and white cement, gypsum, and limestone.

Detailed abundances for a large sample of giant stars in the globular cluster 47 Tucanae (NGC 104)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cordero, M. J.; Pilachowski, C. A.; Johnson, C. I.

2014-01-01

47 Tuc is an ideal target to study chemical evolution and globular cluster (GC) formation in massive more metal-rich GCs, as it is the closest massive GC. We present chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu in 164 red giant branch stars in the massive GC 47 Tuc using spectra obtained with both the Hydra multifiber spectrograph at the Blanco 4 m telescope and the FLAMES multiobject spectrograph at the Very Large Telescope. We find an average [Fe/H] = –0.79 ± 0.09 dex, consistent with literature values, as well as overabundances of alpha-elementsmore » ([α/Fe] ∼ 0.3 dex). The n-capture process elements indicate that 47 Tuc is r process-dominated ([Eu/La] = +0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anticorrelation, a signature typically seen in Galactic GCs, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] ∼ –0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A Kolmogorov-Smirnov test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of asymptotic giant branch nucleosynthesis yields.« less

Geochemical Consequences of Lithospheric Delamination in the Eastern Mediterranean: Evidence From Young Turkish Basalts

NASA Astrophysics Data System (ADS)

Furman, T.; Kurkcuoglu, B.; Plummer, C.

2007-12-01

Magmatism associated with continental collision is increasingly attributed to major disturbance of or within the lithosphere. Geochemical and isotopic data on post-collisional primitive mafic lavas from across the Anatolian plate enable us to assess the effects of lithospheric delamination (slab rollback and breakoff) as indicated by geophysical studies. The Anatolian province displays geodynamically complex manifestations of the closure of neo-Tethys and the collision between Africa and Europe that commenced circa 30 Ma. The current south- southwestward motion of Anatolia, a.k.a. "Turkish escape", is accommodated by slab rollback along the Hellenic trench and orogenic collapse along both the eastern and western margins of the microplate. Volcanism occurs primarily along the fault zones that border and cross-cut Anatolia, and major element characteristics of the lavas vary with both space and time. In Western Anatolia, early Miocene collisional calc- alkaline magmatism was followed by Quaternary alkaline volcanism (Alici et al. 1998, 2002; Aldanmaz et al. 2000, 2006) related to orogenic collapse, presumably resulting from slab rollback. Orogenic collapse in Eastern Anatolia is facilitated by slab breakoff as determined by geophysical studies (Zor et al. 2003; Angus et al. 2006; Lei & Zhao 2007). This transition was accompanied a change from mid-Miocene calc-alkaline to Quaternary alkaline volcanism (e.g., Yilmaz 1990; Pearce et al. 1990). Central Anatolia displays calc-alkaline and tholeiitic volcanism, including alkali olivine basalts; plate tectonic reconstructions (Lyberis et al. 1992) indicate that the African slab did not reach Central Anatolia. Sr-Nd isotope values from each volcanic province define linear arrays that converge upon a common unradiogenic value typical of global depleted mantle. We suggest that mafic volcanism throughout Anatolia is supported by a common asthenospheric component, modified by identifiable, location-specific additions. In areas of lithospheric removal, young basalts have Sr-Nd values close to that of the inferred asthenospheric source, whereas older lavas display more enriched signatures. Limited Pb isotopic data fall within the range of Atlantic and Pacific Ocean sediments, suggesting the mantle signature is masked or strongly influenced by sediments. We focus on the Sivas volcanics, northernmost of the Central provinces, where the most highly magnesian lavas of Anatolia are found. Incompatible trace element considerations suggest that the Sivas suite provides key insights into the nature of the common source region. These lavas have MORB- and OIB-like values of most incompatible trace elements e.g., La/Nb, Ba/Nb, Ba/Rb, Rb/Sr and Th/La, and lack positive Pb anomalies characteristic of crustal interaction. Their geochemical and isotopic compositions - and comparisons between Sivas and areas of orogenic collapse to the east and west - provide new information on the interaction between lithospheric and asthenospheric materials across Turkey. References: Aldanmaz et al. 2000 JVGR 102, 67-95; Aldanmaz et al. 2006 Lithos 86, 50-76; Alici et al. 1998 JVGR 85, 423-446; Alici et al. 2002 JVGR 115, 487-510; Angus et al. 2006 GJI 166, 1335-1346; Lei & Zhao 2007 EPSL 257, 14-28; Lyberis et al. 1992 Tectonophysics 204, 1-15; Pearce et al. 1990 JVGR 44, 189-229; Yilmaz 1990 JVGR 44, 69-87; Zor et al. 2003 GRL 30, doi: 10.1029/2003GL018192

A preliminary study on the insect fauna of Al-Baha Province, Saudi Arabia, with descriptions of two new species

PubMed Central

El-Hawagry, Magdi S.; Khalil, Mohammed W.; Sharaf, Mostafa R.; Hassan H. Fadl; Aldawood, Abdulrahman S.

2013-01-01

Abstract A preliminary study was carried out on the insect fauna of Al-Baha Province, south-western part of Saudi Arabia. A total number of 582 species and subspecies (few identified only to the genus level) belonging to 129 families and representing 17 orders were recorded. Two of these species are described as new, namely: Monomorium sarawatensis Sharaf & Aldawood, sp. n. [Formicidae, Hymenoptera] and Anthrax alruqibi El-Hawagry sp. n. [Bombyliidae, Diptera]. Another eight species are recorded for the first time in Saudi Arabia, namely: Xiphoceriana arabica (Uvarov, 1922) [Pamphagidae, Orthoptera], Pyrgomorpha conica (Olivier, 1791) [Pyrgomorphidae, Orthoptera], Catopsilia florella (Fabricius, 1775) [Pieridae, Lepidoptera], Anthrax chionanthrax (Bezzi, 1926) [Bombyliidae, Diptera], Spogostylum near tripunctatum Pallas in Wiedemann, 1818 [Bombyliidae, Diptera], Cononedys dichromatopa (Bezzi, 1925) [Bombyliidae, Diptera], Mydas sp. [Mydidae, Diptera], and Hippobosca equina Linnaeus, 1758 [Hippoboscidae, Diptera]. Al-Baha Province is divided by huge and steep Rocky Mountains into two main sectors, a lowland coastal plain at the west, known as “Tihama”, and a mountainous area with an elevation of 1500 to 2450 m above sea level at the east, known as “Al-Sarat or Al-Sarah” which form a part of Al-Sarawat Mountains range. Insect species richness in the two sectors (Tihama and Al-Sarah) was compared, and the results showed that each of the two sectors of Al-Baha Province has a unique insect community. The study generally concluded that the insect faunal composition in Al-Baha Province has an Afrotropical flavor, with the Afrotropical elements predominant, and a closer affiliation to the Afrotropical region than to the Palearctic region or the Eremic zone. Consequently, we tend to agree with those biogeographers who consider that parts of the Arabian Peninsula, including Al-Baha Province, should be included in the Afrotropical region rather than in the Palaearctic region or the Eremic zone. PMID:23794807

AFRRI (Armed Forces Radiobiology Research Institute) Reports, October, November and December 1987.

DTIC Science & Technology

1988-03-01

cells (Blakely et al., 1979), mouse BalbC 3T3 cells (Ngo et al., 1981), cells grown in multicellular spheroids (Durand and Olive , 1976), in situ mela...0 radiation. It appeared that an experimental elemental diet was associated with both an enhanced cellular proliferation in the blood-forming tissues...elemental diet for I week before irradiation, and the mean survival time was 59 days. Beginning the diet after irradiation offered no protection. Vitamin E

Rotordynamic Analysis with Shell Elements for the Transfer Matrix Method

DTIC Science & Technology

1989-08-01

consistent kindness and extraordinarily good direction in the completion of this work. I am very pleased to acknowledge my brothers in Christ. Vinai ...modelling used in the transfer ma- trix approach. Rouch et al., (1979), Nelson (1980), To (1981), Greenhill et al., (1985), and Gupta (1986) have all...Reliability in Design, Vol. 107, pp. 4 2 1-4 3 0 . Gupta , A.K., 1986, --Finite Element Analysis of Vibration of Tapered Beams," Shock and Vibration

Effect of multi-element addition of Alnico alloying elements on structure and magnetic properties of SmCo5-based ribbons

NASA Astrophysics Data System (ADS)

Bian, Lu-peng; Li, Ying; Han, Xu-hao; Cheng, Jin-yun; Qin, Xiao-ning; Zhao, Yan-qiu; Sun, Ji-bing

2018-02-01

New SmCo5 + x wt% Alnico composite ribbons melt-spun at 40 m/s are designed by multi-element addition of Alnico alloy into SmCo5 matrix, and their structure and magnetic properties are investigated. The results show that the main phase in x ≤ 2.5 ribbons is Sm(Co,M)5, whereas the main phase changes into Sm(Co,M)7 at x = 4.0-8.5, and simultaneously that the content of Al-rich and amorphous phases increases with increasing x. The hard magnetic properties of the ribbons are found to improve with an increase in Alnico content, and particularly the average magnetic properties reach maximum, i.e., Hc = 19.6 ± 1.2 kOe, Mr = 47.7 ± 3.4 emu/g and M2T = 59.1 ± 5.6 emu/g, at x = 4.0. The main reasons for such improvement are that the finer grains divided by three grain boundaries exist in main phase, the dispersed Al-Ni and Al-Co-rich phases distribute in grains and grain boundaries, and the Fe-rich Alnico alloying elements dissolve into Sm(Co,M)7 matrix phase. However, when x > 4.0, the gradually increasing Al-Co and amorphous phases lead to the reduction of hard magnetic properties.

Toward Efficient Military Retirement Accrual Charges

DTIC Science & Technology

2017-01-01

benefited from reviews provided by Al Robbert of RAND and David Rodney of the CNA Corporation. 1 CHAPTER ONE Introduction Primary elements of the costs ...leaving the military. This report focuses on retirement benefits . Public Law (PL) 98–94, enacted in 1984 and implemented in fiscal year (FY) 1985...in the current budget the cost of future retirement benefits asso- ciated with current manning decisions. Under PL 98–94, DoD includes an accrual

Employee Involvement White Collar Work Force (Phase 1)

DTIC Science & Technology

1991-07-01

TITLE AND SUBTITLE Employee Involvement White Collar Work Force (Phase 1) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...N COMMITTEE August 1991 NSRP 0337 AL EFFECTS TRANSFER Employee Involvement White Collar Work Force (Phase 1) UNITED STATES NAVY David Taylor Research...report. AS used In the above, “Persons acting on behalf of the United States Navy” includes any employee , contractor, or subcontractor to the

Corrosion resistant PEM fuel cell

DOEpatents

Li, Y.; Meng, W.J.; Swathirajan, S.; Harris, S.J.; Doll, G.L.

1997-04-29

The present invention contemplates a PEM fuel cell having electrical contact elements (including bipolar plates/septums) comprising a titanium nitride coated light weight metal (e.g., Al or Ti) core, having a passivating, protective metal layer intermediate the core and the titanium nitride. The protective layer forms a barrier to further oxidation/corrosion when exposed to the fuel cell`s operating environment. Stainless steels rich in Cr, Ni, and Mo are particularly effective protective interlayers. 6 figs.

Effect of Ca and RE additions on microstructures and tensile properties of AZ31 alloys

NASA Astrophysics Data System (ADS)

Fu, Li; Le, Qichi; Tang, Yan; Sun, Jingying; Jia, Yonghui; Song, Zetian

2018-05-01

Microstructures and tensile properties of AZ31 magnesium alloys with the same amount of Ca and RE (Gd + La) additions are investigated. The results show that Al2Ca new phases form after adding Ca elements, Al2Gd and Al11La3 new phases form after adding Gd and La elements, and formations of Al-Ca and Al-RE phases could decrease Mg17Al12 phases and refine grains. Al2Ca and Al11La3 phases are crushed into granules because of severe deformation during hot extrusion, while Al2Gd phases are not. Room temperature (TR) and 150 °C (T150°C) tensile tests results reveal that both AZ31-1.5Ca and AZ31-1.5RE as-extruded alloys exhibit superior comprehensive tensile properties when compared to AZ31 as-extruded alloy, however, AZ31-1.5Ca as-extruded alloy could be a better choice in view of the costs. Textures images of as-extruded alloys indicate that 1.5 wt% Ca and RE additions affects little on textures of AZ31 as-extruded alloy, therefore, morphologies of second phases and average grain sizes are the leading cause of tensile properties of as-extruded alloys.

Terrestrial Chemical Alteration of Hot Desert Meteorites

NASA Astrophysics Data System (ADS)

Crozaz, G.; Floss, C.

2001-12-01

Large numbers of meteorites have recently been recovered from terrestrial hot deserts. They include objects whose study holds the promise of significantly increasing our knowledge of the origin and petrogenesis of rare groups of meteorites (e.g., martian and lunar rocks, ureilites, etc). However, these meteorites have typically been exposed to harsh desert conditions for more than 10,000 yr since their fall on earth. A number of alterations have been described, including mineralogical and chemical changes (e.g., Crozaz and Wadhwa, 2001, and references therein). Through weathering, Fe-bearing minerals are progressively altered into clays and iron oxides and hydroxides, which often fill cracks and mineral fractures, together with terrestrial quartz and carbonates. In addition, for whole rock samples, elevated Ba, Sr, and U seem to be the telltale signs of terrestrial contamination (e.g., Barrat et al., 1999). In our work, we use the rare earth elements (REE) as monitors of terrestrial alteration. These elements are important because they are commonly used to decipher the petrogenesis and chronology of meteorites. We have made in-situ concentration measurements, by secondary ion mass spectrometry (SIMS), of individual grains in shergottites (assumed to have formed on Mars), lunar, and angritic meteorites. Terrestrial contamination, in the form of LREE enrichment and Ce anomalies, is encountered in the olivine and pyroxene, the two minerals with the lowest REE concentrations, of all objects analyzed. However, the contamination is highly heterogeneous, affecting some grains and not others of a given phase. Therefore, provided one uses a measurement technique such as SIMS to obtain data on individual grains and to identify the unaltered ones, it is still possible to obtain geochemical information about the origins of hot desert meteorites. On the other hand, great caution must be exercised if one uses data for whole rocks or mineral separates. The U-Pb, Rb-Sr and Sm-Nd systematics are likely to be affected by terrestrial contamination even in samples with a fresh appearance. Leachates are particularly suspicious (Crozaz and Wadhwa, 2001; Dreibus et al., 2001). In the case of shergottites which have proven difficult to date (Nyquist et al., 2001), this is a complicating and especially unfortunate factor. References: Barrat et al. (1999) MAPS 34, 91-97. Crozaz G. and Wadhwa M. (2001) GCA 65, 971-978. Dreibus et al. (2001) MAPS, in press. Nyquist et al. (2001) Space Sci. Rev., in press.

The Ecological Genomics of Fungi: Repeated Elements in Filamentous Fungi with a Focus on Wood-Decay Fungi

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murat, Claude; Payen, Thibaut; Petitpierre, Denis

2013-01-01

In the last decade, the genome of several dozen filamentous fungi have been sequenced. Interestingly, vast diversity in genome size was observed (Fig. 2.1) with 14-fold differences between the 9 Mb of the human pathogenic dandruff fungus (Malassezia globosa; Xu, Saunders, et al., 2007) and the 125 Mb of the ectomycorrhizal black truffle of P rigord (Tuber melanosporum; Martin, Kohler, et al., 2010). Recently, Raffaele and Kamoun (2012) highlighted that the genomes of several lineages of filamentous plant pathogens have been shaped by repeat-driven expansion. Indeed, repeated elements are ubiquitous in all prokaryote and eukaryote genomes; however, their frequencies canmore » vary from just a minor percentage of the genome to more that 60 percent of the genome. Repeated elements can be classified in two major types: satellites DNA and transposable elements. In this chapter, the different types of repeated elements and how these elements can impact genome and gene repertoire will be described. Also, an intriguing link between the transposable elements richness and diversity and the ecological niche will be highlighted.« less

A dietary strategy for the management of artemether-lumefantrine-induced cardiovascular and renal toxicity.

PubMed

Asiedu-Gyekye, Isaac Julius; Seidu, Mahmood Abdulai; N'guessan, Banga Benoit; Frimpong-Manso, Samuel; Sarkodie, Joseph Edusei; Adjei, Samuel; Kutu, Schevadnazy; Osei-Little, Joseph; Nyarko, Alexander Kwadwo; Debrah, Philip

2016-09-06

Unsweetened natural cocoa has antimalarial properties. Unsweetened natural cocoa powder (UNCP), obtained as a result of the removal of cocoa butter from a cocoa bean protects against malaria episodes. Cocoa powder, which is prepared after removal of the cocoa butter, contains about 1.9 % theobromine and 0.21 % caffeine. Concomitant consumption of cocoa and artemether/lumefantrine (A/L) is a common practice in Ghana, West Africa. This study seeks to determine the elemental composition of UNCP and its protective effect on the heart and kidney against (A/L) administration. Energy dispersive x-ray fluorescence spectroscopy was used to detect the quality and quantity of the elemental composition in UNCP. Thereafter, 30 nonmalarious male guinea pigs were divided into five groups of six animals each. One group was administered with 75 mg/kg body weight A/L only and another group distilled water (control group). The rest received 300 mg/kg, 900 mg/kg and 1500 mg/kg body weight UNCP for 14 days orally and A/L for the last 3 days (ie day 11 to day 14). Biochemical and histopathological examinations were carried out after euthanisation of the animals. A total of thirty-eight (38) micro and macro elements were detected with the ED-XRF. Macro elements like sodium (Na), magnesium (Mg), aluminium (Al), phosphorus (P), chlorine (Cl), potassium (K), calcium (Ca), manganese (Mn) and iron (Fe) and micro elements like chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), and lead (Pb) were identified and evaluated. Biochemical analysis revealed increases in HDL levels (p>0.05) while there were decreases in LDL levels (p>0.05), creatine kinase and AST levels (P<0.05) in animals that received UNCP compared to A/L only administered group. Urea levels reduced significantly by 53 % (p<0.05) in group that received 1500 mg/kg UNCP. Histopathological examinations of the heart and kidney buttressed the protective effects of cocoa administration. The percentage of recommended daily allowance of UNCP for chromium is 3750 % for men and 5250 % for women while % RDA for copper corresponds to 103.6 % in both sexes. UNCP proved to possess cardioprotective and renoprotective potential during artemether-lumefantrine administration.

SIMS Investigations on Growth and Sector Zoning in Natural Hydrothermal Quartz: Isotopic and Trace Element Analyses

NASA Astrophysics Data System (ADS)

May, E.; Vennemann, T. W.; Baumgartner, L. P.; Meisser, N.

2014-12-01

Quartz is the most abundant mineral in the Earth's crust and is found in virtually every geological context. Despite its ubiquity and the detailed studies on the conditions of quartz crystallization, some questions concerning its growth and sector zoning with regard to trace element incorporation and oxygen isotope fractionations and the implications thereof for interpretations on the conditions of formation remain (e.g., Jourdan et al., 2009). This study presents new in-situ measurements of trace element and oxygen isotope ratios on natural hydrothermal quartz from an extensional gold-bearing quartz vein in the western Swiss Alps. The temperature of formation of the veins is estimated by quartz-hematite oxygen isotope thermometry to be about 360°C. A detailed SEM-CL study of this sample shows cyclic lamellar growth, alternating with phases of dissolution that are directly followed by macro-mosaic growth of the quartz, before returning to a cyclic lamellar growth again. Trace element concentrations (measured for Na, K, Li, Al, and Ti) notably showed Al/Si variations of three orders of magnitude and coupled Al and Li variations, likely substituting for Si in different growth zones with lower values in macro-mosaic zones precipitating after the period of dissolution. The oxygen isotope composition of the crystal, in contrast, is homogeneous through all growth zones (δ18O values between 15.6‰ and 16.2‰) indicating that the fluid must have been buffered by the host-rock and/or the source of the fluid remained the same despite the period of quartz dissolution. Furthermore, the temperature during crystallization of the quartz crystal has likely also remained similar. The fact that no variations are measured in oxygen isotope compositions but some variations in trace element contents may suggest that changes in pressure were important during the formation of this quartz crystal. Give the pressure effects on the solubility of quartz (Fournier and Potter, 1982), both the cyclic character of quartz growth and perhaps also the changes in Al/Si may be related to pressure variations caused by seismic activity during retrograde Alpine metamorphism. A-L. Jourdan et al. (2009) Mineralogical Magazine, 73, 615-632. R.O. Fournier and R.W. Potter (1982) Geochimica et Cosmochimica Acta, 46, 1969-1973.

Preclinical Studies of Induced Pluripotent Stem Cell-Derived Astrocyte Transplantation in ALS

DTIC Science & Technology

2012-10-01

Pluripotent Stem Cell -Derived Astrocyte Transplantation in ALS PRINCIPAL INVESTIGATOR: Nicholas J. Maragakis, M.D...Pluripotent Stem Cell -Derived Astrocyte Transplantation in ALS 5b. GRANT NUMBER W81XWH-10-1-0520 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d...into astrocytes following transplantation. 15. SUBJECT TERMS Stem Cells , iPS cells, astrocytes, familial ALS 16. SECURITY CLASSIFICATION OF

Halogens in normal- and enriched-basalts from Central Indian Ridge (18-20°S): Testing the E-MORB subduction origin hypothesis

NASA Astrophysics Data System (ADS)

Ruzie, L.; Burgess, R.; Hilton, D. R.; Ballentine, C. J.

2012-12-01

Basalts emitted along oceanic ridges have often been subdivided into two categories: the Normal-MORB and the Enriched-MORB, anomalously enriched in highly incompatible elements. Donnelly et al. (2004) proposed that the formation of enriched sources is related to two stages of melting. The first one occurs in subduction zones where the mantle wedge is enriched by the addition of low-degree melts of subducted slab. The second stage of melting occurs beneath ocean ridges. Because of their incompatibility, relatively high concentrations and distinct elemental compositions in surface reservoirs, the heavy halogens (Cl, Br, I) are good tracers to detect the slab contribution in E-MORB sources. However, the halogen systematics in mantle reservoirs remains poorly constrained mainly because of their very low abundance in materials of interest. An innovative halogen analytical technique, developed at the University of Manchester, involving neutron irradiation of samples to convert halogens to noble gases provides detection limits unmatched by any other technique studies [Johnson et al. 2000]. For the first time Cl, Br and I can now be determined in appropriate samples. We focus on the content of halogens in the glassy margins of basalts erupted along the CIR from 18-20°S and the off-axis Gasitao Ridge. Our set of samples contains both N- and E-MORB and is fully described in terms of major and trace elements, as well as 3He/4He ratios and water concentrations [Murton et al., 2005; Nauret et al., 2006; Füri et al., 2011; Barry et al., in prep.]. The halogen concentration range is between 10 and 140 ppm for Cl, 30 and 500 ppb for Br and 0.8 and 10 ppb for I. The higher concentrations are found in E-MORB samples from the northern part of ridge axis. Comparing our data with previous halogen studies, our sample suites fall within the range of N-MORB from East Pacific Ridge (EPR) and Mid-Atlantic Ridge (MAR) [Jambon et al. 1995; Deruelle et al. 1992] and in the lower range of E-MORB from Macquarie Island [Kendrick et al., 2012]. The concentrations are not related to superficial processes. The on-axis samples display a relatively restricted range (6.9-8.6wt%) of MgO contents, suggesting no control of the crystallisation processes. The basalts were erupted between 3900-2000 m bsl, so no appreciable degassing of halogens would be expected. The strong correlation, which exists between the halogens and other incompatible elements (e.g., Rb, La), also rules out seawater assimilation. Therefore, concentrations and elemental ratios can be directly linked to melting and source features. Estimates of halogens abundances in the depleted-mantle source are 4 ppm Cl, 14 ppb Br and 0.3 ppb I. These low abundances, which are in agreement with values derived for sub-continental mantle from coated diamonds [Burgess et al., 2002], suggest that, like noble gases, the upper mantle is degassed of its halogens. Critically, the halogen elemental ratios show no significant variations along the axial ridge and off-axis ridge or between N-MORB and E-MORB: Br/Cl=0.00147±0.00014, I/Cl=0.000021±0.000005; I/Br=0.0142±0.0036. These ratios are similar to E-MORB from Macquarie Island [Kendrick et al., 2012]. This observation is thus not consistent with subduction as a source of halogen enrichment in E-MORB.

Role of Y in the oxidation resistance of CrAlYN coatings

NASA Astrophysics Data System (ADS)

Domínguez-Meister, S.; El Mrabet, S.; Escobar-Galindo, R.; Mariscal, A.; Jiménez de Haro, M. C.; Justo, A.; Brizuela, M.; Rojas, T. C.; Sánchez-López, J. C.

2015-10-01

CrAlYN coatings with different aluminum (4-12 at.%) and yttrium (2-5 at.%) contents are deposited by d.c. reactive magnetron sputtering on silicon and M2 steel substrates using metallic targets and Ar/N2 mixtures. The influence of the nanostructure and chemical elemental distribution on the oxidation resistance after heating in air at 1000 °C is studied by means of cross-sectional scanning electron microscopy (X-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and glow discharge optical emission spectroscopy (GD-OES). The sequential exposure to the metallic targets during the synthesis leads to a multilayer structure where concentration of metallic elements (Cr, Al and Y) is changing periodically. A good oxidation resistance is observed when Al- and Y-rich regions are separated by well-defined CrN layers, maintaining crystalline coherence along the columnar structure. This protective behavior is independent of the type of substrate and corresponds to the formation of a thin mixed (Al, Cr)-oxide scale that protects the film underneath. The GD-OES and XRD analysis have demonstrated that Y acts as a reactive element, blocking the Fe and C atoms diffusion from the steel and favoring higher Al/Cr ratio in the passivation layer after heating. The coating with Y content around 4 at.% exhibited the best performance with a thinner oxide scale, a delay in the CrN decomposition and transformation to Cr2N, and a more effective Fe and C blocking.

Geochemical background/baseline values in top soils of Campania region: assessment of the toxic elements threat to ecosystem and human health

NASA Astrophysics Data System (ADS)

de Vivo, B.; Lima, A.; Albanese, S.; Bove, M.; Cicchella, D.; Civitillo, D.; Cosenza, A.; Grezzi, G.

2009-04-01

In the late years an intense geochemical prospecting activity on the whole territory of Campania region (Southern Italy) has been carried aiming at the definition of the geochemical backgrounds/baselines at both regional and local scale. At the end of 2003 the first edition of an atlas containing 200 maps showing the distribution patterns of 40 chemical elements on the whole regional territory was published (De Vivo et al., 2003, 2006a; Albanese et al., 2007a). The atlas provided a base knowledge of environmental status of the region and allowed to individuate some critical areas to be further investigated by topsoils sampling follow up activity; the topsoils are considered as the best media in order to examine closely the sources and the distribution patterns of harmful elements at a local scale. The topsoils sampling was mainly focused on anthropized areas (at urban and metropolitan scale), industrial settlments, brownfields and intensely cultivated zones, aimed at: • showing the distribution of concentration values and to determine baseline values (or backgrounds, depending on local conditions) of each analyzed element (38) in the top soils; • assessing harmful elements pollution levels and their geographic distribution; • providing reliable analytical data for assessment of toxic element pollution threat to ecosystem and human health; • creating a sound basis for policy makers and legislators who need to address the public concerns regarding environmental pollution. Five atlases (De Vivo et al., 2006b; Albanese et al., 2007b; Lima et al., 2007; Fedele et al., 2007 Cicchella et al., 2009) were produced reporting soil geochemical maps compiled using 1620 samples collected both in the metropolitan and provincial area of Napoli and in the cities of Avellino, Benevento, Caserta and Salerno. Further studies were also carried out taking into account Pb isotopes (Cicchella et al., 2008a), PGE's (Cicchella et al., 2003; 2008b) and bioavailability of harmful elements (Albanese, 2008) distributions to better discriminate the influence of human activities on urban environment. A detailed analysis of harmful elements distribution and some organic compounds (PCB and PAH's) was also completed for the Bagnoli brownfield area, in the western sector of the city of Napoli (Tarzia et al., 2002; De Vivo and Lima, 2008; Albanese et al, in press). Since Bagnoli is located inside an active volcanic field (Campi Flegrei) characterized by a strong geothermal activity that generates hydrothermal fluids, the definition of the anthropic impact on environment for this area was complicated by the presence of two main contamination sources, one natural (originating from the hydrothermal activity) and one anthropogenic (from the industrial activity). At present, a geochemical prospecting based on soil and water sampling is also being completed on two contiguous areas mainly devoted to agriculture in correspondence of the north-western coastal sector of Campania Region territory (Domitio-Flegreo Littoral e Agro Aversano). The latter studies aim at defining the impact of agricultural activities (including the use of fertilizers) on soil and deep waters. All the geochemical data obtained for the whole territory of Campania have been also spatially compared with cancer mortality data distribution (Montella et al., 1996) to individuate, at least, some spatial correspondences between high concentration levels of harmful elements and mortality incidence (Albanese et al., 2008). An interesting overlapping has been found for the Napoli metropolitan area for some elements and cancer types: Zn-Cd-rich areas overlap with areas of high prostate-cancer mortality; bladder and pancreatic cancer are correlated with Pb-Sb-rich areas, whereas, bronchial-tracheal-lung cancer is correlated with As-, Cd- and Pb-rich areas. References ALBANESE, S., DE VIVO, B., LIMA, A. & CICCHELLA, D. 2007a. J. Geoch. Expl., 93, 21-34. ALBANESE, S., LIMA, A., DE VIVO, B. & CICCHELLA, D. 2007b. Geochemical Environmental Atlas of the Soils of Avellino. Aracne Editrice, Roma. ALBANESE, S. 2008. Geochemistry: Expl., Env., Anal., 8, 49-57. ALBANESE S., DE LUCA M. L., DE VIVO B., LIMA A. and GREZZI G., 2008. In: Environmental Geochemistry: Site characterization, Data analysis and Case histories (De Vivo B., Belkin H. E. and Lima A., Eds). Elsevier, Amsterdam, 391-404. ALBANESE, S., CIVITILLO, D., COSENZA, A., DE VIVO, B., & LIMA., A., J. Geoch. Explor.. In press. CICCHELLA, D., DE VIVO, B. & LIMA, A. 2003. Science of the Total Environment, 308 (1-3), 121-131. CICCHELLA, D., DE VIVO, B. & LIMA, A. 2005. Geochemistry: Expl., Env., Anal., 5, 29-40. CICCHELLA, D., DE VIVO, B., LIMA, A., ALBANESE, S., MCGILL, R.A.R. & PARRISH, R.R. 2008a. Geochemistry: Expl.,. Env., Ana.s, 8, 103-112. CICCHELLA, D., FEDELE, L., DE VIVO, B., ALBANESE, S. & LIMA, A. 2008b. Geochemistry: Expl., Env., Anal., 8, 31-40. CICCHELLA, D., ALBANESE, S., DE VIVO, B., LIMA, A., GREZZI, G. & ZUPPETTA, A. 2009. Geochemical Environmental Atlas of the soils of Benevento. Aracne Editrice, Roma. DE VIVO B. and LIMA A., 2008. In: Environmental Geochemistry: Site characterization, Data analysis and Case histories (De Vivo B., Belkin H. E. and Lima A., Eds). Elsevier, Amsterdam, 355-385. DE VIVO, B., LIMA, A., ALBANESE, S. & CICCHELLA, D. 2003. Geochemical Environmental Atlas of Campania Region. De Frede Editore, Napoli. DE VIVO, B., LIMA, A., ALBANESE, S. & CICCHELLA, D. 2006a. Geochemical Environmental Atlas of Campania Region. Aracne Editrice, Roma. DE VIVO, B., CICCHELLA, D., LIMA, A. & ALBANESE, S. 2006b. Geochemical Environmental Atlas of the Urban and Provincial Soils of Napoli. Aracne Editrice, Roma. FEDELE, L., DE VIVO, B., LIMA, A., CICCHELLA, D. & ALBANESE, S. 2007. Geochemical Environmental Atlas of the Soils of Salerno. Aracne Editrice, Roma. LIMA, A., DE VIVO, B., GREZZI, G., ALBANESE, S. & CICCHELLA, D. 2007. Geochemical Environmental Atlas of the Soils of Caserta. Aracne Editrice, Roma. MONTELLA, M., BIDOLI, E., DE MARCO, M. R., REDIVO, A., AND FRANCESCI, S. 1996. Atlante della mortalita` per tumori nella Regione campania, 1998-92. Lega Italiana per la Lotta contro i Tumori, Istituto Nazionale Tumori, Napoli. TARZIA, M., DE VIVO, B., SOMMA, R., AYUSO, R.A., MCGILL, R.A.R. & PARRISH, R.R. 2002. Anthropogenic versus natural pollution: an environmental study of an industrial site under remediation (Naples, Italy). Geochemistry: Expl., Env., Anal., 2, 45-56.

Trace Elements and Carbon and Nitrogen Stable Isotopes in Organisms from a Tropical Coastal Lagoon

PubMed Central

van Hattum, B.; de Boer, J.; van Bodegom, P. M.; Rezende, C. E.; Salomons, W.

2010-01-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (δ13C and δ15N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by 15N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between δ15N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption. PMID:20217062

Trace elements and carbon and nitrogen stable isotopes in organisms from a tropical coastal lagoon.

PubMed

Pereira, A A; van Hattum, B; de Boer, J; van Bodegom, P M; Rezende, C E; Salomons, W

2010-10-01

Trace elements (Fe, Mn, Al, Zn, Cr, Cu, Ni, Pb, Cd, Hg, and As) and stable isotope ratios (delta(13)C and delta(15)N) were analyzed in sediments, invertebrates, and fishes from a tropical coastal lagoon influenced by iron ore mining and processing activities to assess the differences in trace element accumulation patterns among species and to investigate relations with trophic levels of the organisms involved. Overall significant negative relations between trophic level (given by (15)N) and trace element concentrations in gastropods and crustaceans showed differences in internal controls of trace element accumulation among the species of different trophic positions, leading to trace element dilution. Generally, no significant relation between delta(15)N and trace element concentrations was observed among fish species, probably due to omnivory in a number of species as well as fast growth. Trace element accumulation was observed in the fish tissues, with higher levels of most trace elements found in liver compared with muscle and gill. Levels of Fe, Mn, Al, and Hg in invertebrates, and Fe and Cu in fish livers, were comparable with levels in organisms and tissues from other contaminated areas. Trace element levels in fish muscle were below the international safety baseline standards for human consumption.

An On-Line Technology Information System (OTIS) for Advanced Life Support

NASA Technical Reports Server (NTRS)

Levri, Julie A.; Boulanger, Richard; Hoganm John A.; Rodriquez, Luis

2003-01-01

An On-line Technology Information System (OTIS) is currently being developed for the Advanced Life Support (ALS) Program. This paper describes the preliminary development of OTIS, which is a system designed to provide centralized collection and organization of technology information. The lack of thorough, reliable and easily understood technology information is a major obstacle in effective assessment of technology development progress, trade studies, metric calculations, and technology selection for integrated testing. OTIS will provide a formalized, well-organized protocol to communicate thorough, accurate, current and relevant technology information between the hands-on technology developer and the ALS Community. The need for this type of information transfer system within the Solid Waste Management (SWM) element was recently identified and addressed. A SWM Technology Information Form (TIF) was developed specifically for collecting detailed technology information in the area of SWM. In the TIF, information is requested from SWM technology developers, based upon the Technology Readiness Level (TRL). Basic information is requested for low-TRL technologies, and more detailed information is requested as the TRL of the technology increases. A comparable form is also being developed for the wastewater processing element. In the future, similar forms will also be developed for the ALS elements of air revitalization, food processing, biomass production and thermal control. These ALS element-specific forms will be implemented in OTIS via a web-accessible interface,with the data stored in an object-oriented relational database (created in MySQLTM) located on a secure server at NASA Ames Research Center. With OTIS, ALS element leads and managers will be able to carry out informed research and development investment, thereby promoting technology through the TRL scale. OTIS will also allow analysts to make accurate evaluations of technology options. Additionally, the range and specificity of information solicited will help educate technology developers of programmatic needs.

The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO 3 Fe 3Al, Co 3Al, and Ni 3Al based intermetallic phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co and Ti within the AlNi-based matrix phase. In our paper we report the results of first-principles calculations of the site preference of ternarymore » alloying additions in DO 3 Fe 3Al, Co 3Al and Ni 3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which corresponds to experimental situation, Ti and Fe are found to occupy the sites, while Co and Ni prefer the sites of the DO 3 lattice. Finally, an important finding is that the magnetic moments of transition metals in Fe 3Al and Co 3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co are added as a ternary element.« less

The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO{sub 3} Fe{sub 3}Al, Co{sub 3}Al, and Ni{sub 3}Al based intermetallic phases

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samolyuk, G. D.; Stocks, G. M.; Újfalussy, B.

Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co, and Ti within the AlNi-based matrix phase. In this paper, we report the results of first-principles calculations of the site preference of ternarymore » alloying additions in DO{sub 3} Fe{sub 3}Al, Co{sub 3}Al, and Ni{sub 3}Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which correspond to experimental situation, Ti and Fe are found to occupy the α sites, while Co and Ni prefer the γ sites of the DO{sub 3} lattice. An important finding is that the magnetic moments of transition metals in Fe{sub 3}Al and Co{sub 3}Al are ordered ferromagnetically, whereas the Ni{sub 3}Al were found to be nonmagnetic unless the Fe or Co is added as a ternary element.« less

The distribution alloying elements in alnico 8 and 9 magnets: Site preference of ternary Ti, Fe, Co, and Ni additions in DO 3 Fe 3Al, Co 3Al, and Ni 3Al based intermetallic phases

DOE PAGES

Samolyuk, G. D.; Újfalussy, B.; Stocks, G. M.

2014-11-07

Recently, interest in alnico magnetic alloys has been rekindled due to their potential to substitute for rare-earth based permanent magnets provided modest improvements in their coercivity can be achieved without loss of saturation magnetization. Recent experimental studies have indicated that atomic and magnetic structure of the two phases (one AlNi-based, the other FeCo-based) that comprise these spinodally decomposed alloy is not as simple as previously thought. A key issue that arises is the distribution of Fe, Co and Ti within the AlNi-based matrix phase. In our paper we report the results of first-principles calculations of the site preference of ternarymore » alloying additions in DO 3 Fe 3Al, Co 3Al and Ni 3Al alloys, as models for the aluminide phase. For compound compositions that are Al rich, which corresponds to experimental situation, Ti and Fe are found to occupy the sites, while Co and Ni prefer the sites of the DO 3 lattice. Finally, an important finding is that the magnetic moments of transition metals in Fe 3Al and Co 3Al are ordered ferromagnetically, whereas the Ni3Al were found to be nonmagnetic unless the Fe or Co are added as a ternary element.« less

The Effect of Plume Impingement on Lithospheric Preservation Beneath the Kenya Rift, East Africa

NASA Astrophysics Data System (ADS)

Hamblock, J. M.; Anthony, E. Y.; Chesley, J. T.; Omenda, P. A.

2003-12-01

The Kenya Rift is located at the transition between Archean Tanzanian craton and Proterozoic mobile belt. Currently, discrepancies exist between geochemical and geophysical interpretations of lithospheric preservation in the Kenya Rift. Seismic data show a sharp vertical boundary between low velocity mantle in the axis and higher velocity mantle on the flanks, which is interpreted to reflect lithospheric erosion from the axis (Mechie et al., 1997; Prodehl et al., 1997). However, geochemical data suggest that the lithospheric mantle is intact beneath both the axis and the flanks. Different elemental groups are observed for rocks from Kenya (Hamblock et al., 2003). One group is characterized by elemental concentrations greater than ocean island basalts (OIB), negative K and Sr anomalies, and Lan and Cen greater than 100. These characteristics are found in silica-undersaturated rocks such as nephelinites, basanites, and some alkali basalts from the flank and the axis and are interpreted to represent melting of an enriched lithosphere. A second group is characterized by elemental concentrations less than OIB, a flat overall pattern, and Lan and Cen less than 100. This pattern is found in alkali basalts and hypersthene-normative rocks. The multi-element pattern varies minimally between axis and flank lavas, with axial lavas containing higher concentrations of Ba (Macdonald et al., 2001). Because rocks of both groups are present in the axis and the flanks, lithosphere appears to be intact across the Kenya Rift, and strong lateral contrasts in composition do not exist. Sr, Nd, and Pb isotopes also suggest that ancient lithospheric mantle is present in Kenya and Tanzania (Macdonald et al., 2001; Paslick et al., 1995). A consistent difference between axis and flank is lower La/Yb for axis lavas, indicating that they originate in the spinel stability field. Flank lavas, regardless of their silica saturation, have higher La/Yb and are interpreted to come from garnet peridotite. Discrepancies between geophysical and geochemical data exist for other parts of the East African Rift as well. In the axis of the rift in Tanzania, tomography suggests that upwelling asthenosphere has eroded the lithosphere (Nyblade, 2002). However, gravity models (Simiyu and Keller, 1997, 2001) and the presence of subchondritic 187Os/188Os in spinel and garnet-bearing xenoliths (TRD of 2.6 Ga) suggest that the lithosphere is intact (Chesley et al., 1999). In contrast, for the Tanzanian craton, Os isotopes, gravity, and tomography are consistent with 2.5-2.9 Ga lithosphere existing to depths of 140 km and a broad thermal and geochemical anomaly (plume?) below the lithosphere (Chesley et al., 1999; Owens et al., 2000; Nyblade et al., 2000; Simiyu and Keller, 1997, 2001). In the Sidamo region of Ethiopia, Os isotopes suggest that ancient depleted mantle is present and has been modified by recent melt percolation (Lorand et al., 2003; Reisberg et al., in press). Finally, for Ethiopian flood basalts, element chemistry, petrology, and 3He/4He (Marty et al., 1996; Scarsi and Craig, 1996) indicate a dominant role for plume. Os isotopes (Davies et al., 2003), however, are lower than PUM, indicating that an ancient lithospheric mantle reservoir is present. In order to help resolve the discrepancies between geophysical and geochemical interpretations, we will obtain petrologic and isotopic data for xenoliths and mafic lavas in both east-west and north-south directions. The lavas span a wide range of silica saturation and La/Yb ratios, and thus are intended to represent lithospheric as well as asthenospheric sources.

A comparative study between two smoothing strategies for the simulation of contact with large sliding

NASA Astrophysics Data System (ADS)

Batailly, Alain; Magnain, Benoît; Chevaugeon, Nicolas

2013-05-01

The numerical simulation of contact problems is still a delicate matter especially when large transformations are involved. In that case, relative large slidings can occur between contact surfaces and the discretization error induced by usual finite elements may not be satisfactory. In particular, usual elements lead to a facetization of the contact surface, meaning an unavoidable discontinuity of the normal vector to this surface. Uncertainty over the precision of the results, irregularity of the displacement of the contact nodes and even numerical oscillations of contact reaction force may result of such discontinuity. Among the existing methods for tackling such issue, one may consider mortar elements (Fischer and Wriggers, Comput Methods Appl Mech Eng 195:5020-5036, 2006; McDevitt and Laursen, Int J Numer Methods Eng 48:1525-1547, 2000; Puso and Laursen, Comput Methods Appl Mech Eng 93:601-629, 2004), smoothing of the contact surfaces with additional geometrical entity (B-splines or NURBS) (Belytschko et al., Int J Numer Methods Eng 55:101-125, 2002; Kikuchi, Penalty/finite element approximations of a class of unilateral contact problems. Penalty method and finite element method, ASME, New York, 1982; Legrand, Modèles de prediction de l'interaction rotor/stator dans un moteur d'avion Thèse de doctorat. PhD thesis, École Centrale de Nantes, Nantes, 2005; Muñoz, Comput Methods Appl Mech Eng 197:979-993, 2008; Wriggers and Krstulovic-Opara, J Appl Math Mech (ZAMM) 80:77-80, 2000) and, the use of isogeometric analysis (Temizer et al., Comput Methods Appl Mech Eng 200:1100-1112, 2011; Hughes et al., Comput Methods Appl Mech Eng 194:4135-4195, 2005; de Lorenzis et al., Int J Numer Meth Eng, in press, 2011). In the present paper, we focus on these last two methods which are combined with a finite element code using the bi-potential method for contact management (Feng et al., Comput Mech 36:375-383, 2005). A comparative study focusing on the pros and cons of each method regarding geometrical precision and numerical stability for contact solution is proposed. The scope of this study is limited to 2D contact problems for which we consider several types of finite elements. Test cases are given in order to illustrate this comparative study.

Gamma-rays and heat-treatment conversions of point defects in massive rose quartz from the Borborema Pegmatite Province, Northeast Brazil

NASA Astrophysics Data System (ADS)

Guzzo, Pedro L.; Barreto, Sandra B.; Miranda, Milena R.; Gonzaga, Raysa S. G.; Casals, Sandra A.

2017-11-01

An extensive characterization of trace elements and point defects in rose quartz from the Borborema Pegmatite Province (BPP) in the northeast of Brazil was carried out by complementary spectroscopic methods. The aim here was to document the change in the configuration of point defects into the quartz lattice induced by heat-treatment and ionizing radiation. The samples were extracted from the core of two granitic rare element (REL) pegmatites, Taboa (Carnaúba dos Dantas, RN) and Alto do Feio (Pedra Lavrada, PB). The contents of Al, P, Ti, Ni, Fe, Ge, Li, Be, B and K were measured by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Polished plates were heat-treated at 500 and 1000 °C and then irradiated with 50 kGy of γ rays. Point defects were characterized by optical (UV-Vis), infrared (IR), and electron paramagnetic resonance (EPR) spectroscopies. In the as-received condition, [AlO4/H]0 centers, Li- and B-dependent OH defects were observed. Point defects related to Al and Li species were significantly affected by heat-treatment at 1000 °C and/or γ radiation. Paramagnetic centers such as [AlO4]0, [GeO4/Li]0, [TiO4/Li]0 and [O2 3-/Li]0 were created by the diffusion of Li+ ions from their original diamagnetic centers related to substitutional Al3+ and OH-species. The smoky color developed after irradiation and the signal intensities of the paramagnetic centers were independent from the original rose color grade. The samples from the Taboa (TB) pegmatite showed the highest concentration of Al, Ti, Fe and Li elements as well as the highest signal intensities for [AlO4]0, [AlO4/H]0, [GeO4/Li]0 and [TiO4/Li]0 centers. Although TB also showed the higher concentration of B element, the intensity of the 3597 cm-1 IR band related to [BO4/H]0 centers was higher for Alto do Feio (AF) samples. This result suggests that the uptake of B into the quartz core of each pegmatite took place through different mechanisms. It was concluded that the change in the point defect configuration was essentially governed by the motion of Li species whose incorporation into the quartz lattice is closely related to Al concentration.

Influence of alloying elements on the oxidation behavior of NbAl3

NASA Technical Reports Server (NTRS)

Hebsur, M. G.; Stephens, J. R.; Smialek, J. L.; Barrett, C. A.; Fox, D. S.

1988-01-01

NbAL3 is one candidate material for advanced aeropropulsion systems because of its high melting point, low density, and good oxidation resistance. Although NbAl3 has the lowest oxidation rate among the binary Nb-Al alloys, it does not form exclusive layers of protective Al2O3 scales. Recently Perkin et al., have shown the feasibility of forming alumina scales on Nb-Al alloys at greatly reduced Al contents. However, the objective was to maintain the high Al content, and hence low density, while achieving the capability of growing protective alumina scales. Alloy development followed approaches similar to those used successfully for superalloys and oxidation resistant MCrAlY coatings. Among the three elements examined (Ti, Si, and Cr) as ternary additions to Nb-Al3, Cr was the most effective in favoring the selective oxidation of Al. Nb-41Al-8Cr formed exclusive layers of alumina and had a k sub p value of 0.22 mg squared/cm (sup 4)/hr at 1200 C. The addition of 1 wt percent Y to this alloy was also beneficial, resulting in nearly an order of magnitude decrease in K sub p at 1200 C. Further improvements were achieved by adding about 1 wt percent Si to the quaternary alloy. The k sub p value of 0.012 mg squared/cm (sup 4)/hr for Nb-40Al-8Cr-1Y-1Si at 1200 C was identical to the best NiAl + Zr alloys. These NbAl3 alloys also exhibited excellent cyclic oxidation resistance for 100 hr at 1200 C, being nearly equivalent to NiAl + Zr.

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-06-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

An Overview of the Effects of Alloying Elements on the Properties of Lightweight Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C Steel

NASA Astrophysics Data System (ADS)

Xing, Jia; Wei, Yinghui; Hou, Lifeng

2018-04-01

In this review, the influences of alloying elements on the phase constitution, density, and stacking fault energy of Fe-(15-35) Mn-(5-12) Al-(0.3-1.2) C lightweight steel are discussed. The mechanical properties of austenite single-phase and austenite-ferrite dual-phase Fe-Mn-Al-C steels processed by different procedures are also statistically analyzed. The austenite single-phase steel was found to possess superior strength and plasticity. Three reasonable explanations for the mechanism of plastic deformation are presented, namely, shear band-induced plasticity, microband-induced plasticity, and slip band refinement-induced plasticity.

Deposition behavior of mixed binary metallic powders in cold spraying process

NASA Astrophysics Data System (ADS)

Zhou, X. L.; Mou, S. J.; Wu, X. K.; Zhang, J. S.

2011-10-01

In the present study, Zn/Al composite coating was selected for the typical case to study the deposition behavior and the deformation of binary mixing particles in cold spraying process by means of an experiment and numerical simulation. The experimental results demonstrated that the coating had a dense microstructure, and that Zn and Al were uniformly distributed in the coating. Al particles deformed more severely than Zn particles, and extensively deformed Al particles had a local jet-metallic mixing area. The steel substrate underwent a small amount of deformation when impacted by Zn particles, whereas the substrate did not deform when impacted by Al particles. XRD results show that the Zn/Al composite coating did not form a new phase, and only resulted in the mechanical mixing of Zn and Al, producing a pseudo-alloy coating. In addition, a binary Zn/Al multiparticle impact was first simulated using the finite element analysis software ANSYS/LS-DYNA. The effective plastic strain contour, which enabled the description of the particle deposit procedure, was demonstrated. The plastic deformation evolution of Zn and Al particles in the composite coating was analyzed individually, and the curves of effective plastic strain versus time of typical monitored elements at the edge of the Zn and Al particles were plotted. The simulations showed good concordance with the experimental results.

Mechanisms and FEM Simulation of Chip Formation in Orthogonal Cutting In-Situ TiB₂/7050Al MMC.

PubMed

Xiong, Yifeng; Wang, Wenhu; Jiang, Ruisong; Lin, Kunyang; Shao, Mingwei

2018-04-15

The in-situ TiB₂/7050Al composite is a new kind of Al-based metal matrix composite (MMC) with super properties, such as low density, improved strength, and wear resistance. This paper, for a deep insight into its cutting performance, involves a study of the chip formation process and finite element simulation during orthogonal cutting in-situ TiB₂/7050Al MMC. With chips, material properties, cutting forces, and tool geometry parameters, the Johnson-Cook (J-C) constitutive equation of in-situ TiB₂/7050Al composite was established. Then, the cutting simulation model was established by applying the Abaqus-Explicit method, and the serrated chip, shear plane, strain rate, and temperature were analyzed. The experimental and simulation results showed that the obtained material's constitutive equation was of high reliability, and the saw-tooth chips occurred commonly under either low or high cutting speed and small or large feed rate. From result analysis, it was found that the mechanisms of chip formation included plastic deformation, adiabatic shear, shearing slip, and crack extension. In addition, it was found that the existence of small, hard particles reduced the ductility of the MMC and resulted in segmental chips.

Trace Element Compositions of Pallasite Olivine Grains and Pallasite Origin

NASA Technical Reports Server (NTRS)

Mittlefehldt, David W.; Herrin, J. S.

2010-01-01

Pallasites are mixtures of metal with magnesian olivine. Most have similar metal compositions and olivine oxygen isotopic compositions; these are the main-group pallasites (PMG). The Eagle Station grouplet of pallasites (PES) have distinctive metal and olivine compositions and oxygen isotopic compositions. Pallasites are thought to have formed at the core-mantle boundary of their parent asteroids by mixing molten metal with solid olivine of either cumulatic or restitic origin. We have continued our investigation of pallasite olivines by doing in situ trace element analyses in order to further constrain their origin. We determined Al, P, Ca, Ga and first row transition element contents of olivine grains from suite of PMG and PES by LA-ICP-MS at JSC. Included in the PMG suite are some that have anomalous metal compositions (PMG-am) and atypically ferroan olivines (PMG-as). Our EMPA work has shown that there are unanticipated variations in olivine Fe/Mn, even within those PMG that have uni-form Fe/Mg. Manganese is homologous with Fe2+, and thus can be used the same way to investigate magmatic fractionation processes. It has an advantage for pallasite studies in that it is unaffected by redox exchange with the metal. PMG can be divided into three clusters on the basis of Mn/Mg; low, medium and high that can be thought of as less, typically and more fractionated in an igneous sense. The majority of PMG have medium Mn/Mg ratios. PMG-am occur in all three clusters; there does not seem to be any relationship between putative olivine igneous fractionation and metal composition. The PMG-as and one PMG-am make up the high Mn/Mg cluster; no PMG are in this cluster. The high Mn/Mg cluster ought to be the most fractionated (equivalent to the most Fe-rich in igneous suites), yet they have among the lowest contents of incompatible lithophile elements Al and Ti and the two PMG-as in this cluster also have low Ca and Sc contents. This is inconsistent with simple igneous fractionation on a single, initially homogeneous parent asteroid. For Al and Ti, the low and high Mn/Mg clusters have generally uniform contents, while the medium cluster has wide ranges. This is also true of analyses of duplicate grains from the medium cluster pallasites which can have very different Al and Ti contents. Those from the low and high clusters do not. These observations suggest that pallasite olivines are not cumulates, but rather are restites from high degrees of melting. The moderately siderophile elements P and Ga show wide ranges in the high Mn/Mg cluster, but very uniform compositions in the medium cluster, opposite the case for Al and Ti. There is no correlation of P or Ga and Fe/Mn as might be expected if redox processes controlled the contents of moderately siderophile elements in the olivines. The lack of correlation of P could reflect equilibration with phosphates, although there is no correlation of Ca with P as might be expected

The effects of Ni, Mo, Ti and Si on the mechanical properties of Cr free Mn steel (Fe-25Mn-5Al-2C)

NASA Technical Reports Server (NTRS)

Schuon, S. R.

1982-01-01

The FeMnAlC alloys may hold potential as Cr-free replacements for high strategic material iron base superalloys, but little is known about their intermediate temperature (650 C to 870 C) mechanical properties. The effects of alloying elements on the mechanical properties of model FeMnAlC alloys were studied. Results showed that modified FeMnAlC alloys had promising short term, intermediate temperature properties but had relatively poor stress rupture lives at 172 MPa and 788 C. Room temperature and 788 C tensile strength of FeMnAlC alloys were better than common cast stainless steels. Changes in room temperature tensile and 788 C tensile strength and ductility, and 788 C stress rupture life were correlated with changes in Ni, Mo, Ti, and Si levels due to alloying effects on interstitial carbon levels and carbide morphology. Fe-25Mn-5Al-2C had a very poor stress rupture life at 172 MPa and 788 C. Addition of carbide-forming elements improved the stress rupture life.

Modeling of Substitutional Site Preference in Ordered Intermetallic Alloys

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Noebe, Ronald D.; Honecy, Frank

1998-01-01

We investigate the site substitution scheme of specific alloying elements in ordered compounds and the dependence of site occupancy on compound stoichiometry, alloy concentration. This basic knowledge, and the interactions with other alloying additions are necessary in order to predict and understand the effect of various alloying schemes on the physical properties of a material, its response to various temperature treatments, and the resulting mechanical properties. Many theoretical methods can provide useful but limited insight in this area, since most techniques suffer from constraints in the type of elements and the crystallographic structures that can be modeled. With this in mind, the Bozzolo-Ferrante-Smith (BFS) method for alloys was designed to overcome these limitations, with the intent of providing an useful tool for the theoretical prediction of fundamental properties and structure of complex systems. After a brief description of the BFS method, its use for the determination of site substitution schemes for individual as well as collective alloying additions to intermetallic systems is described, including results for the concentration dependence of the lattice parameter. Focusing on B2 NiAl, FeAl and CoAl alloys, the energetics of Si, Ti, V, Cr, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Hf, Ta and W alloying additions are surveyed. The effect of single additions as well as the result of two simultaneous additions, discussing the interaction between additions and their influence on site preference schemes is considered. Finally, the BFS analysis is extended to ternary L1(sub 2) (Heusler phase) alloys. A comparison between experimental and theoretical results for the limited number of cases for which experimental data is available is also included.

Development and Evaluation of TiAl Sheet Structures for Hypersonic Applications

NASA Technical Reports Server (NTRS)

Draper, S. L.; Krause, D.; Lerch, B.; Locci, I. E.; Doehnert, B.; Nigam, R.; Das, G.; Sickles, P.; Tabernig, B.; Reger, N.;

Finite Element Simulations of Micro Turning of Ti-6Al-4V using PCD and Coated Carbide tools

NASA Astrophysics Data System (ADS)

Jagadesh, Thangavel; Samuel, G. L.

2017-02-01

The demand for manufacturing axi-symmetric Ti-6Al-4V implants is increasing in biomedical applications and it involves micro turning process. To understand the micro turning process, in this work, a 3D finite element model has been developed for predicting the tool chip interface temperature, cutting, thrust and axial forces. Strain gradient effect has been included in the Johnson-Cook material model to represent the flow stress of the work material. To verify the simulation results, experiments have been conducted at four different feed rates and at three different cutting speeds. Since titanium alloy has low Young's modulus, spring back effect is predominant for higher edge radius coated carbide tool which leads to the increase in the forces. Whereas, polycrystalline diamond (PCD) tool has smaller edge radius that leads to lesser forces and decrease in tool chip interface temperature due to high thermal conductivity. Tool chip interface temperature increases by increasing the cutting speed, however the increase is less for PCD tool as compared to the coated carbide tool. When uncut chip thickness decreases, there is an increase in specific cutting energy due to material strengthening effects. Surface roughness is higher for coated carbide tool due to ploughing effect when compared with PCD tool. The average prediction error of finite element model for cutting and thrust forces are 11.45 and 14.87 % respectively.

Binary Phase Diagrams and Thermodynamic Properties of Silicon and Essential Doping Elements (Al, As, B, Bi, Ga, In, N, P, Sb and Tl)

PubMed Central

Mostafa, Ahmad; Medraj, Mamoun

2017-01-01

Fabrication of solar and electronic silicon wafers involves direct contact between solid, liquid and gas phases at near equilibrium conditions. Understanding of the phase diagrams and thermochemical properties of the Si-dopant binary systems is essential for providing processing conditions and for understanding the phase formation and transformation. In this work, ten Si-based binary phase diagrams, including Si with group IIIA elements (Al, B, Ga, In and Tl) and with group VA elements (As, Bi, N, P and Sb), have been reviewed. Each of these systems has been critically discussed on both aspects of phase diagram and thermodynamic properties. The available experimental data and thermodynamic parameters in the literature have been summarized and assessed thoroughly to provide consistent understanding of each system. Some systems were re-calculated to obtain a combination of the best evaluated phase diagram and a set of optimized thermodynamic parameters. As doping levels of solar and electronic silicon are of high technological importance, diffusion data has been presented to serve as a useful reference on the properties, behavior and quantities of metal impurities in silicon. This paper is meant to bridge the theoretical understanding of phase diagrams with the research and development of solar-grade silicon production, relying on the available information in the literature and our own analysis. PMID:28773034

ALLOY COMPOSITION FOR NEUTRONIC REACTOR CONTROL RODS

DOEpatents

Lustman, B.; Losco, E.F.; Snyder, H.J.; Eggleston, R.R.

1963-01-22

This invention relates to alloy compositons suitable as cortrol rod material consisting of, by weight, from 85% to 85% Ag, from 2% to 20% In, from up to 10% of Cd, from up to 5% Sn, and from up to 1.5% Al, the amount of each element employed being determined by the equation X + 2Y + 3Z + 3W + 4V = 1.4 and less, where X, Y, Z, W, and V represent the atom fractions of the elements Ag, Cd, In, Al and Sn. (AEC)

Low TCR nanocomposite strain gages

NASA Technical Reports Server (NTRS)

Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

2012-01-01

A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

Comparison of light harmonic generation in Al and Ge consisted silicate materials

NASA Astrophysics Data System (ADS)

Smirnov, Vitaly A.; Vostrikova, Liubov I.

2018-04-01

The silicate materials are perspective for different areas of laser physics and photonics. In this paper the comparison of the nonlinear conversion with the generation of the light harmonic in Al- and Ge-containing silicate materials is presented. The peculiarities of the processes of the light harmonic generation in dependence on the concentrations of the chemical components are discussed and the influences of the additional small inclusion of the elements of fifth group and the rare-earth elements are estimated.

Atomistic modeling and simulation of the role of Be and Bi in Al diffusion in U-Mo fuel

NASA Astrophysics Data System (ADS)

Hofman, G. L.; Bozzolo, G.; Mosca, H. O.; Yacout, A. M.

2011-07-01

Within the RERTR program, previous experimental and modeling studies identified Si as the alloying addition to the Al cladding responsible for inhibiting Al interdiffusion in the UMo fuel. However, difficulties with reprocessing have rendered this choice inappropriate, leading to the need to study alternative elements. In this work, we discuss the results of an atomistic modeling effort which allows for the systematic study of several possible alloying additions. Based on the behavior observed in the phase diagrams, beryllium or bismuth additions suggest themselves as possible options to replace Si. The results of temperature-dependent simulations using the Bozzolo-Ferrante-Smith (BFS) method for the energetics for varying concentrations of either element are shown, indicating that Be could have a substantial effect in stopping Al interdiffusion, while Bi does not. Details of the calculations and the dependence of the role of each alloying addition as a function of temperature and concentration (of beryllium or bismuth in Al) are shown.

Variation of Aging Precipitates and Mechanical Strength of Al-Cu-Li Alloys Caused by Small Addition of Rare Earth Elements

NASA Astrophysics Data System (ADS)

Ma, Yun-long; Li, Jin-feng

2017-09-01

The effect of small rare earth (RE) addition of 0.11%Ce, 0.2%Er and 0.082%Sc on aging precipitates and mechanical strength of an Al-(3.3-4.2)Cu-1.2Li-X alloy were investigated. It is found that Cu-rich residual particles containing RE element exist in the solutionized alloy, which leads to a decrease of dissolved Cu concentration in the solutionized matrix. Like RE-free alloy, the main aging precipitate types in RE-containing alloy are T1 (Al2CuLi) and θ' (Al2Cu), but their fraction is decreased. The strength of the corresponding alloys is therefore lowered by the small RE addition. Combined with the analysis of some reported references, it is proposed that the effect of small RE addition on Al-Cu-Li alloy strength is also associated with the Cu and Li concentrations and their ratio.

Characterization of members to stellar kinematic groups using chemical tagging

NASA Astrophysics Data System (ADS)

Tabernero, H. M.

2014-10-01

In this thesis we have characterized more than one thousand late-type stars. For this characterization we have been making use of high resolution spectroscopy (R > 40,000) taken in different spectrographs, HERMES at the Mercator telescope in La Palma, FOCES in the 2.2m telescope at Calar Alto, the Coudé-Echelle spectrograph at 2 m-the Alfred- Jensch-Teleskop in Tautenburg, and UVES at the Very Large Telescope in La Silla. Stellar spectroscopy, in particular at high-resolution, is a modern tool that allows us to extract a lot of information of a given star. In particular, we have obtained their atmospheric parameters, namely: effective temperature (Teff), surface gravity (log g), microturbulent velocity (ξ), and iron abundance ([Fe/H], used as a metallicity proxy). An automatic code (StePar) has been developed. This code allows to derive stellar atmospheric parameters (Teff , log g, ξ, and [Fe/H]) only in a few minutes. Also, with these parameters at hand we have derived chemical abundances for 20 different chemical elements: Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ba, Ce, and Nd, which offer many or at least some isolated transitions in the wavelength range of the spectra taken with these spectrographs. This work comprises two publications in Astronomy & Astrophysics. The first one is about chemical tagging applied to the Hyades SC (see Chapter 2 or Tabernero et al. 2012). The second paper is a in-depth study of the chemical composition of candidate members to the Ursa Major MG (see Chapter 3 or Tabernero et al. 2015). Additionally there is another chapter that comprises the analysis of Galactic stars within the GAIA ESO Survey stars (GES, Gilmore et al. 2012; Randich & Gilmore 2013) whose data have contributed to the publication of some release (Lanzafame et al. 2014; Smiljanic et al. 2014) and science papers (Jofre et al. 2014; Sousa et al. 2014; Spina et al. 2014a,b) that made use the survey results. The two papers included in this thesis deal with the characterization of late-type stars (F, G, and K spectral types). In particular, this thesis is based on the determination of stellar atmospheric parameters and element abundances.

Effect of alloying elements and coiling temperature on the recrystallization behavior and the bainitic transformation in TRIP steels

NASA Astrophysics Data System (ADS)

Han, Seongho; Seong, Hwangoo; Ahn, Yeonsang; Garcia, C. I.; DeArdo, A. J.; Kim, Inbae

2009-08-01

The effects of alloying elements and coiling temperature on recrystallization behavior and bainitic transformation were investigated based on 0.07C-Mn-Cr-Nb steel with a low carbon equivalent. Based on the ferrite recrystallization behavior, the proper intercritical annealing temperature of all studied steels was suggested to produce TRIP steel with good strength and elongation balance. All steels coiled at 550 °C showed much faster ferrite recrystallization behavior than steels coiled at 700 °C. In addition to the coiling temperature, the effect of increasing carbon content on the ferrite recrystallization was minor at a coiling temperature of 550 °C, but much more prominent at a coiling temperature of 700 °C. The highest Mo added steel showed the best strength and elongation balance, and the highest carbon and Mo added steel showed the highest tensile strength at a coiling temperature of 550 °C. The steel containing a higher amount of elemental Al (0.7 wt.% Al) exhibited much better elongation than the lower Al added steel (0.04 wt.% Al) in TS 780 MPa grade, about 24 % and 19 %, respectively.

Inteins, introns, and homing endonucleases: recent revelations about the life cycle of parasitic genetic elements

PubMed Central

Gogarten, J Peter; Hilario, Elena

2006-01-01

Self splicing introns and inteins that rely on a homing endonuclease for propagation are parasitic genetic elements. Their life-cycle and evolutionary fate has been described through the homing cycle. According to this model the homing endonuclease is selected for function only during the spreading phase of the parasite. This phase ends when the parasitic element is fixed in the population. Upon fixation the homing endonuclease is no longer under selection, and its activity is lost through random processes. Recent analyses of these parasitic elements with functional homing endonucleases suggest that this model in its most simple form is not always applicable. Apparently, functioning homing endonuclease can persist over long evolutionary times in populations and species that are thought to be asexual or nearly asexual. Here we review these recent findings and discuss their implications. Reasons for the long-term persistence of a functional homing endonuclease include: More recombination (sexual and as a result of gene transfer) than previously assumed for these organisms; complex population structures that prevent the element from being fixed; a balance between active spreading of the homing endonuclease and a decrease in fitness caused by the parasite in the host organism; or a function of the homing endonuclease that increases the fitness of the host organism and results in purifying selection for the homing endonuclease activity, even after fixation in a local population. In the future, more detailed studies of the population dynamics of the activity and regulation of homing endonucleases are needed to decide between these possibilities, and to determine their relative contributions to the long term survival of parasitic genes within a population. Two outstanding publications on the amoeba Naegleria group I intron (Wikmark et al. BMC Evol Biol 2006, 6:39) and the PRP8 inteins in ascomycetes (Butler et al.BMC Evol Biol 2006, 6:42) provide important stepping stones towards integrated studies on how these parasitic elements evolve through time together with, or despite, their hosts. PMID:17101053

Influence of alloying elements on the oxidation behavior of NbAl3

NASA Technical Reports Server (NTRS)

Hebsur, M. G.; Stephens, J. R.; Smialek, J. L.; Barrett, C. A.; Fox, D. S.

1989-01-01

NbAl3 is one candidate material for advanced aeropropulsion systems because of its high melting point, low density, and good oxidation resistance. Although NbAl3 has the lowest oxidation rate among the binary Nb-Al alloys, it does not form exclusive layers of protective Al203 scales. Recently Perkin et al., have shown the feasibility of forming alumina scales on Nb-Al alloys at greatly reduced Al contents. However, the objective was to maintain the high Al content, and hence low density, while achieving the capability of growing protective alumina scales. Alloy development followed approaches similar to those used successfully for superalloys and oxidation resistant MCrAly coatings. Among the three elements examined (Ti, Si, and Cr) as ternary additions to Nb-Al3, Cr was the most effective in favoring the selective oxidation of Al. Nb-41Al-8Cr formed exclusive layers of alumina and had a k sub p value of 0.22 mg squared/cm (sup 4)/hr at 1200 C. The addition of 1 wt percent Y to this alloy was also beneficial, resulting in nearly an order of magnitude decrease in K sub p at 1200 C. Further improvements were achieved by adding about 1 wt percent Si to the quaternary alloy. The k sub p value of 0.012 mg squared/cm (sup 4)/hr for Nb-40Al-8Cr-1Y-1Si at 1200 C was identical to the best NiAl + Zr alloys. These NbAl3 alloys also exhibited excellent cyclic oxidation resistance for 100 hr at 1200 C, being nearly equivalent to NiAl + Zr.

Orthopyroxenes as Recorders of Diogenite Petrogenesis: Al-Cr-Ti Systematics

NASA Astrophysics Data System (ADS)

Fowler, G. W.; Papike, J. J.; Spilde, M. N.; Shearer, C. K.

1993-07-01

This research represents a continuing effort to understand the petrogenesis of diogenites and their relationship to eucrites. Our present suite of 17 diogenites includes: Aioun El Atrouss, Ellemeet, Garland, Ibbenburen, Johnstown, Manegoan, Peckelsheim, Roda, Shalka, Tatahouine, EET 83246, EET 83247, EET 87530, EET A79002, LEW 88008, and olivine diogenites ALH 84001 and ALH A77256. In our previous studies [1,2], we reported major, minor, and trace element systematics for a subgroup of 13 of these samples. In these studies, we concluded that Fe/Mg was compromised by post-crystallization annealing reactions. We also demonstrated [1] strong, positive correlations between Cr and Al along several trajectories on a Cr-Al data display. REE and Zr-Ti systematics indicate that most sampled diogenites represent cumulates from similar basaltic melts. These modeled melt compositions are similar to eucrites but show a greater compositional range. Here we further explore the Al-Cr-Ti systematics. Figure 1 (figures include over 1,000 high quality EMP analyses) is a Ti-Al plot that shows a main trend with a positive correlation between Ti and Al. Rhoda and one of the assemblages in polymict Garland have elevated Ti concentrations relative to the main trend while Manegoan has relatively depleted Ti concentrations. Figure 2 is a (Cr+Ti) vs. Al plot with a main trend that shows a strong, positive correlation between (Cr+Ti) and Al. Manegoan occupies the high (Cr+Ti)-Al end of the trend while Peckelsheim occupies the low end. Olivine diogenite ALH A77256 falls distinctly off the trend. However, ALH 84001, our only other olivine diogenite, plots with the other diogenite in the main trend. Several things are indicated by these systematics. The positive correlation of (Cr+Ti) vs. Al indicate that the most important charge balance couples are ^VITi^4+-^IVAl(sub)2, ^VITi^3+-^IVAl, ^VICr^3+-^IVAl, and ^VIAl-^IVAl. The ^VIAl-^IVAl couple is relatively more important in olivine diogenite ALH A77256, which accounts for its data plotting below the main trend. It should be noted that the main trend and the ALH A77256 trend have less scatter near the bottom of the data arrays than near the top. In fact, lines drawn through the bottom of the arrays project through the origin. Some of the reason for the scatter, other than subsolidus annealing effects [3], may be the result of different Ti^3+/Ti^4+ ratios in OPX resulting from variable fO2 environments. A possible charge balance equation, for other then quadrilateral components is: ^VITi^3++2^VITi^4++^VICr^3++^VIAl^3+=^IVAl (Na is so low it can be ignored). The cores of most OPX grains probably still retain their igneous signatures; therefore, the high Al, Cr, Ti end of the main trend likely reflects melt compositions enriched in these elements. Acknowledgment. This research was supported by NASA Grant NAGW- 3347 and the Institute of Meteoritics. References. [1] Papike J. J. et. al. (1993) LPS XXIV, 1109-1110. [2] Shearer C. K. et al. (1993) LPS XXIV, 1289-1290. [3] Papike J. J. and Spilde M. N. (1993) This volume. Fig. 1, which appears here in the hard copy, shows Al vs. Ti atoms per formula unit. Fig. 2, which appears here in the hard copy, shows Ti + Cr vs. Al in atoms per formula unit.

Concentrations and bioaccessibilities of trace elements in barbecue charcoals.

PubMed

Sharp, Annabel; Turner, Andrew

2013-11-15

Total and bioaccessible concentrations of trace elements (Al, As, Cd, Cu, Fe, Hg, Mn, Ni, Pb and Zn) have been measured in charcoals from 15 barbecue products available from UK retailers. Total concentrations (available to boiling aqua regia) were greater in briquetted products (with mean concentrations ranging from 0.16 μg g(-1) for Cd to 3240 μg g(-1) for Al) than in lumpwoods (0.007 μg g(-1) for Cd to 28 μg g(-1) for Fe), presumably because of the use of additives and secondary constituents (e.g. coal) in the former. On ashing, and with the exception of Hg, elemental concentrations increased by factors ranging from about 1.5 to 50, an effect attributed to the combustion of organic components and offset to varying extents by the different volatilities of the elements. Concentrations in the ashed products that were bioaccessible, or available to a physiologically based extraction test (PBET) that simulates, successively, the chemical conditions in the human stomach and intestine, exhibited considerable variation among the elements studied. Overall, however, bioaccessible concentrations relative to corresponding total concentrations were greatest for As, Cu and Ni (attaining 100% in either or both simulated PBET phases in some cases) and lowest for Pb (generally <1% in both phases). A comparison of bioaccessible concentrations in ashed charcoals with estimates of daily dietary intake suggest that Al and As are the trace elements of greatest concern to human health from barbecuing. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of X-Ray Microradiographs of Al-Au Interface Quench Profile using Modeling of Solidification Including Double-Diffusion and Convection in the Melt

NASA Technical Reports Server (NTRS)

Bune, Andris V.; Kaukler, William

1999-01-01

Experimental data on Al-0.8Au horizontal solidification of a 1 mm thick specimen in a BN crucible shows the effect of growth rate on the solidification interface shape. For translation rates below 0.5 micron/s the interface maintains a plain and flat shape. When the translation rate is 3 to 5 micron/s or more, the interface appearance changes to two planar zones, with the zone closer to the bottom having higher inclination. The interface shapes were measured by first quenching in place during growth. X-ray microscopy shows the interface shape within the quenched sample by viewing through the side of the specimen. In order to provide theoretical explanation of the phenomena, numerical modeling was undertaken using finite element code FIDAP. Double diffusion convection in Al-0.8Au melt and crystal-melt interface curvature during directional solidification was analyzed numerically. Actual thermophysical properties of Al-0.8Au including the binary Al-Au phase diagram were used. Although convection in the sample is weak, for the slower translation rate convection and diffusion is sufficient for the redistribution of initial compositional stratification caused by gravity. When translation rate is raised, neither convection nor diffusion can provide proper mixing so that solidification temperatures differ significantly near the bottom within the bulk of the sample. As a result, the solid-liquid interface appears to have two planar zones with different inclination.

Photoionization Models of Bromine, Rubidium, and Xenon in Planetary Nebulae

NASA Astrophysics Data System (ADS)

Sterling, Nicholas C.; Porter, Ryan; Spencer, Courteney; Sherrard, Cameroun G.

2017-06-01

We present numerical simulations of the Br, Rb, and Xe ionization balance in five planetary nebulae (PNe). These neutron-capture elements (atomic number Z > 30) can be enriched by s-process nucleosynthesis during the asymptotic giant branch (AGB) evolutionary stage of PN progenitor stars. Recent calculations of photoionization cross sections and rate coefficients for radiative recombination, dielectronic recombination, and charge transfer (Kerlin et al. 2017, in preparation; Sterling & Kerlin 2016, 227th AAS, #238.02; Sterling & Stancil 2011, A&A, 535, A117) allow the Br, Rb, and Xe ionization equilibria to be modeled in PNe for the first time. We have added these elements and their atomic data to Cloudy (Ferland et al. 2013, RMxA&A, 49, 137). We model the PNe IC 418, IC 2501, IC 4191, NGC 2440, and NGC 7027, all of which exhibit emission from multiple Xe ions in the optical data of Sharpee et al. (2007, ApJ, 659, 1265). Multiple Br and Rb ions were also detected in NGC 7027. The model central star temperatures and luminosities, and nebular densities, outer radii, and abundances were optimized to best reproduce the observed intensities of Sharpee et al. We find that IC 418 and NGC 7027 are enriched in Br, Rb, and Xe, in accordance with results for Se and Kr (Sterling et al. 2015, ApJS, 218, 25). Given the small sample size and the weakness of the lines involved, it is not clear whether discrepancies between modeled and observed intensities are due to observational, model, or atomic data uncertainties. This sample will be expanded to include other PNe, such as those in our optical survey (Sherrard et al. poster, this session), which will allow us to test the veracity of the new atomic data for Xe and, for a smaller number of PNe, Br and Rb. Following the methods of Sterling et al. (2015), grids of Cloudy models will be computed to derive ionization correction factors for Br, Rb, and Xe for the first time, allowing their abundances to be determined with higher accuracy than previously possible. We acknowledge support from NSF grant AST-1412928.

Positive Psychology and Disaster Mental Health: Strategies for Working with Children and Adolescents.

PubMed

Vernberg, Eric M; Hambrick, Erin P; Cho, Bridget; Hendrickson, Michelle L

2016-12-01

Positive psychology concepts and principles can be incorporated into preparedness, crisis response, and recovery phases of disaster mental health efforts to address the needs of children, adolescents, and families. This article articulates general developmental considerations for applying positive psychology in disaster mental health contexts and discusses how 5 essential elements of immediate and midterm mass trauma intervention identified by Hobfoll et al. (2007) may be infused in applications of positive psychology for children and adolescents. Specific strategies for working with children, adolescents, and their families in home, community, and school contexts are drawn in part from disaster mental health resources developed jointly by the National Child Traumatic Stress Network and National Center for Posttraumatic Stress Disorder, including the Psychological First Aid Field Operations Guide (Brymer et al., 2006), the Skills for Psychological Recovery Field Operations Guide (Berkowitz et al., 2010), and the Psychological First Aid for Schools Field Operations Manual (Brymer et al., 2012). Two case examples illustrate the use of positive psychology principles. © 2016 Wiley Periodicals, Inc.

Nasir al-Din al-Tusi's Memoir on Astronomy (al-Tadhkira fi cilm al-hay'a)

NASA Astrophysics Data System (ADS)

Ragep, F. J.

Tusi (1201-1274 a.d.) was an Arabic scholar whose writings became the standard texts in several disciplines for several centuries. They include editions of Euclid's Elements and Ptolemy's Almagest, as well as other books on mathematics and astronomy, and books on logic, ethics, religion. He wrote the Tadhkira, to be "a summary account of `astronomy' presented in narrative form. The details are expounded and proofs of the validity are furnished in the Almagest. Indeed, ours would not be a complete science if taken in isolation from the Almagest for it is a report of what is established therein." It is thus not only a sort of running commentary on the Almagest, but also an account of medieval Arabic cosmology. Jamil Ragep has not only translated the text of the Tadhkira, but has also provided a lengthy introduction with a biography of Tusi and a discussion of the context in which the Tadhkira was written and its influence, as well as a detailed and thorough commentary on each section of the text.

The influence of nepheloid layers on global model simulations of 231Pa and 230Th.

NASA Astrophysics Data System (ADS)

Basak, C.; Plancherel, Y.; Khatiwala, S.; Anderson, R. F.

2016-12-01

231Pa and 230Th in the ocean are produced at a constant ratio by Uranium decay but adsorption onto particles removes these tracers differentially. This fractionation process makes it possible to use the elemental 231Pa/230Th ratio as a paleoceanography proxy, frequently used for deriving the strength of Atlantic Meridional Overturning Circulation. The removal process, however, is further complicated by the abundance and composition of the available particle types. Understanding how dissolved tracers interact with the particle field in the ocean is key to better understand the biogeochemical cycling of these particle-reactive elements and their use as a flux tracer in present and past oceans. We here present simulations of the 231Pa/230Th ratio using the Transport Matrix Method (TMM, Khatiwala, 2007), focusing especially on the role of the nepheloid layer in controlling the distribution of these radiotracers. The model simulates each tracer separately, with advective-diffusive transport based on the ECCO ocean state estimate (Stammer et al., 2004). Sources include production by Uranium decay and dust dissolution. Radioactive decay and importantly, reversible scavenging and sedimentation are the main sinks that control the removal of the radiotracers. Similar to previous studies, we consider particle fields consisting of calcium carbonate, opal, particle organic matter, and dust. A novelty is that we explicitly consider the influence of an additional bottom particle layer (nepheloid). Simulations that include a nepheloid layer produce vertical profiles that better fit the observed distribution of 230Th and 231Pa. Specifically, observational data in the South Atlantic and eastern South Pacific indicate a mid-depth inflection (for both Pa and Th), a feature that can only be obtained if a nepheloid layer is included in the simulation. Our simulations reinforce the idea that nepheloid layers play an important role in Pa and Th cycling in the ocean (Deng et al., 2014; Hayes et al., 2015).

Vacuum Pressureless Sintering of Ti-6Al-4V Alloy with Full Densification and Forged-Like Mechanical Properties

NASA Astrophysics Data System (ADS)

Zhang, Ce; Lu, Boxin; Wang, Haiying; Guo, Zhimeng; Paley, Vladislav; Volinsky, Alex A.

2018-01-01

Ti-6Al-4V ingots with a nearly 100% density, fine and homogeneous basket-weave microstructure, and better comprehensive mechanical properties (UTS = 935 MPa, Y.S. = 865 MPa, El. = 15.8%), have been manufactured by vacuum pressureless sintering of blended elemental powders. Coarse TiH2 powder, Al powder (2, 20 μm), V powder, and Al-V master alloy powder were used as raw materials to produce different powder mixtures ( D 50 = 10 μm). Then, the compacts made by cold isostatic pressing were consolidated by different sintering curves. A detailed investigation of different as-sintered samples revealed that a higher density can be obtained by generating transient molten Al in the sintering process. Coarse Al powder and a rapid heating rate under the melting point of Al contribute to molten Al formation. The presence of temporary liquid phase changes the sintering mechanism, accelerating the sintering neck formation, improving sinterability of the powder mixtures. Density of 99.5% was achieved at 1150 °C, which is markedly lower than the sintering temperatures reported for conventional blended elemental powder metallurgy routes. In addition, low interstitial content, especially for oxygen (0.17 wt.%), is obtained by strict process control.

Study of Cu-Al-Ni-Ga as high-temperature shape memory alloys

NASA Astrophysics Data System (ADS)

Zhang, Xin; Wang, Qian; Zhao, Xu; Wang, Fang; Liu, Qingsuo

2018-03-01

The effect of Ga element on the microstructure, mechanical properties and shape memory effect of Cu-13.0Al-4.0Ni- xGa (wt%) high-temperature shape memory alloy was investigated by optical microscopy, SEM, XRD and compression test. The microstructure observation results showed that the Cu-13.0Al-4.0Ni- xGa ( x = 0.5 and 1.0) alloys displayed dual-phase morphology which consisted of 18R martensite and (Al, Ga)Cu phase, and their grain size was about several hundred microns, smaller than that of Cu-13.0Al-4.0Ni alloy. The compression test results proved that the mechanical properties of Cu-13.0Al-4.0Ni- xGa alloys were improved by addition of Ga element owing to the grain refinement and solid solution strengthening, and the compressive fracture strains were 11.5% for x = 0.5 and 14.9% for x = 1.0, respectively. When the pre-strain was 8%, the shape memory effect of 4.2 and 4.6% were obtained for Cu-13.0Al-4.0Ni-0.5 Ga and Cu-13.0Al-4.0Ni-1.0 Ga alloys after being heated to 400 °C for 1 min.

Exploring the influence of constitutive models and associated parameters for the orthogonal machining of Ti6Al4V

NASA Astrophysics Data System (ADS)

Pervaiz, S.; Anwar, S.; Kannan, S.; Almarfadi, A.

2018-04-01

Ti6Al4V is known as difficult-to-cut material due to its inherent properties such as high hot hardness, low thermal conductivity and high chemical reactivity. Though, Ti6Al4V is utilized by industrial sectors such as aeronautics, energy generation, petrochemical and bio-medical etc. For the metal cutting community, competent and cost-effective machining of Ti6Al4V is a challenging task. To optimize cost and machining performance for the machining of Ti6Al4V, finite element based cutting simulation can be a very useful tool. The aim of this paper is to develop a finite element machining model for the simulation of Ti6Al4V machining process. The study incorporates material constitutive models namely Power Law (PL) and Johnson – Cook (JC) material models to mimic the mechanical behaviour of Ti6Al4V. The study investigates cutting temperatures, cutting forces, stresses, and plastic strains with respect to different PL and JC material models with associated parameters. In addition, the numerical study also integrates different cutting tool rake angles in the machining simulations. The simulated results will be beneficial to draw conclusions for improving the overall machining performance of Ti6Al4V.

Investigation of Product Performance of Al-Metal Matrix Composites Brake Disc using Finite Element Analysis

NASA Astrophysics Data System (ADS)

Fatchurrohman, N.; Marini, C. D.; Suraya, S.; Iqbal, AKM Asif

2016-02-01

The increasing demand of fuel efficiency and light weight components in automobile sectors have led to the development of advanced material parts with improved performance. A specific class of MMCs which has gained a lot of attention due to its potential is aluminium metal matrix composites (Al-MMCs). Product performance investigation of Al- MMCs is presented in this article, where an Al-MMCs brake disc is analyzed using finite element analysis. The objective is to identify the potentiality of replacing the conventional iron brake disc with Al-MMCs brake disc. The simulation results suggested that the MMCs brake disc provided better thermal and mechanical performance as compared to the conventional cast iron brake disc. Although, the Al-MMCs brake disc dissipated higher maximum temperature compared to cast iron brake disc's maximum temperature. The Al-MMCs brake disc showed a well distributed temperature than the cast iron brake disc. The high temperature developed at the ring of the disc and heat was dissipated in circumferential direction. Moreover, better thermal dissipation and conduction at brake disc rotor surface played a major influence on the stress. As a comparison, the maximum stress and strain of Al-MMCs brake disc was lower than that induced on the cast iron brake disc.

A Novel Synthesis Routine for Woodwardite and Its Affinity towards Light (La, Ce, Nd) and Heavy (Gd and Y) Rare Earth Elements

PubMed Central

Consani, Sirio; Balić-Žunić, Tonci; Cardinale, Anna Maria; Sgroi, Walter; Giuli, Gabriele; Carbone, Cristina

2018-01-01

A synthetic Cu-Al-SO4 layered double hydroxide (LDH), analogue to the mineral woodwardite [Cu1−xAlx(SO4)x/2(OH)2·nH2O], with x < 0.5 and n ≤ 3x/2, was synthesised by adding a solution of Cu and Al sulphates to a solution with NaOH. The pH values were kept constant at 8.0 and 10.0 by a continuous addition of NaOH. The material obtained had poor crystallinity, turbostratic structure, and consisted of nanoscopic crystallites. The analyses performed in order to characterise the obtained materials (X-ray diffraction (XRD), thermogravimetry (TG), and Fourier Transform Infra-Red (FTIR) spectroscopy) showed that the Cu-Al-SO4 LDH is very similar to woodwardite, although it has a smaller layer spacing, presumably due to a lesser water content than in natural samples. The synthesis was performed by adding light rare earth elements (LREEs) (La, Ce, and Nd) and heavy rare earth elements (HREEs) (Gd and Y) in order to test the affinity of the Cu-Al-SO4 LDH to the incorporation of REEs. The concentration of rare earth elements (REEs) in the solid fraction was in the range of 3.5–8 wt %. The results showed a good affinity for HREE and Nd, especially for materials synthesised at pH 10.0, whereas the affinities for Ce and La were much lower or non-existent. The thermal decomposition of the REE-doped materials generates a mixture of Cu, Al, and REE oxides, making them interesting as precursors in REE oxide synthesis. PMID:29342887

Trace elements in streambed sediments of small subtropical streams on O'ahu, Hawai'i: Results from the USGS NAWQA program

USGS Publications Warehouse

De Carlo, E. H.; Tomlinson, M.S.; Anthony, S.S.

2005-01-01

Data are presented for trace element concentrations determined in the <63 ??m fraction of streambed sediment samples collected at 24 sites on the island of O'ahu, Hawai'i. Sampling sites were classified as urban, agricultural, mixed (urban/agricultural), or forested based on their dominant land use, although the mixed land use at selected sampling sites consisted of either urban and agricultural or forested and agricultural land uses. Forest dominated sites were used as reference sites for calculating enrichment factors. Trace element concentrations were compared to concentrations from studies conducted in the conterminous United States using identical methods and to aquatic-life guidelines provided by the Canadian Council of Ministers of the Environment. A variety of elements including Pb, Cr, Cu and Zn exceeded the aquatic-life guidelines in selected samples. All of the Cr and Zn values and 16 of 24 Cu values exceeded their respective guidelines. The potential toxicity of elements exceeding guidelines, however, should be considered in the context of strong enrichments of selected trace elements attributable to source rocks in Hawai'i, as well as in the context of the abundance of fine-grained sediment in the streambed of O'ahu streams. Statistical methods including cluster analysis, Kruskal-Wallis non-parametric test, correlation analysis, and principal component analysis (PCA) were used to evaluate differences and elucidate relationships between trace elements and sites. Overall, trace element distributions and abundances can be correlated to three principal sources of elements. These include basaltic rocks of the volcanic edifice (Fe, Al, Ni, Co, Cr, V and Cu), carbonate/seawater derived elements (Mg, Ca, Na and Sr), and elements enriched owing to anthropogenic activity (P, Sn, Cd, Sn, Ba and Pb). Anthropogenic enrichment gradients were observed for Ba, Cd, Pb, Sn and Zn in the four streams in which sediments were collected upstream and downstream. The findings of this study are generally similar to but differ slightly from previous work on sediments and suspended particulate matter in streams, from two urban watersheds of O'ahu, Hawai'i. Inter-element associations in the latter were often stronger and indicated a mixture of anthropogenic, agricultural and basaltic sources of trace elements. Some elements fell into different statistical categories in the two studies, owing in part to differences in study design and the hydrogeological constraints on the respective study areas.

Optimisation of the geometry of the drill bit and process parameters for cutting hybrid composite/metal structures in new aircrafts

NASA Astrophysics Data System (ADS)

Isbilir, Ozden

Owing to their desirable strength-to-weight characteristics, carbon fibre reinforced polymer composites have been favourite materials for structural applications in different industries such as aerospace, transport, sports and energy. They provide a weight reduction in whole structure and consequently decrease fuel consumption. The use of lightweight materials such as titanium and its alloys in modern aircrafts has also increased significantly in the last couple of decades. Titanium and its alloys offer high strength/weight ratio, high compressive and tensile strength at high temperatures, low density, excellent corrosion resistance, exceptional erosion resistance, superior fatigue resistance and relatively low modulus of elasticity. Although composite/metal hybrid structures are increasingly used in airframes nowadays, number of studies regarding drilling of composite/metal stacks is very limited. During drilling of multilayer materials different problems may arise due to very different attributes of these materials. Machining conditions of drilling such structures play an important role on tool wear, quality of holes and cost of machining.. The research work in this thesis is aimed to investigate drilling of CFRP/Ti6Al4V hybrid structure and to optimize process parameters and drill geometry. The research work consist complete experimental study including drilling tests, in-situ and post measurements and related analysis; and finite element analysis including fully 3-D finite element models. The experimental investigations focused on drilling outputs such as thrust force, torque, delamination, burr formation, surface roughness and tool wear. An algorithm was developed to analyse drilling induced delamination quantitatively based on the images. In the numerical analysis, novel 3-D finite element models of drilling of CFRP, Ti6Al4V and CFRP/Ti6Al4V hybrid structure were developed with the use of 3-D complex drill geometries. A user defined subroutine was developed to model material and failure behaviour of CFRP. The effects of process parameters on drilling outputs have been investigated and compared with the experimental results. The influences of drill bit geometries have been simulated in this study..

Impact of mineral fertility and bedrock erosion on single-mineral detrital studies: insights from trace-element and Nd-isotope systematics of detrital apatite from the Po River catchment

NASA Astrophysics Data System (ADS)

Malusa', Marco Giovanni; Wang, Jiangang; Garzanti, Eduardo; Villa, Igor M.; Wittman, Hella

2017-04-01

The detrital record provides an archive of mountain erosion that preserves key information for paleotectonic and paleoclimatic reconstructions. Detrital studies are often based on single-mineral analyses (e.g., geo/thermochronologic analyses on apatite and zircon). Their geologic interpretation can be challenging, because the impact of each eroding source on the detrital record is controlled by a range of factors including the rate of erosion and the fertility of chosen minerals in eroded bedrock. Here, we combine (i) a state-of-the art dataset of trace element and Nd isotope fingerprints of detrital apatite, (ii) a comprehensive dataset of apatite-fertility measurements (Malusà et al. 2016), (iii) fission-track data, and (iv) cosmogenic-derived erosion rates from the Po River catchment (Wittmann et al. 2016), to test the impact of mineral fertility and bedrock erosion on the single-mineral detrital signal preserved in the final sediment sink. Our results show that the information provided by accessory minerals, when complemented with accurate mineral fertility measurements, are fully consistent with information provided by the analysis of more abundant framework minerals. We found that trace element and Nd isotope analyses provide a reliable tool to disentangle the complex single-mineral record of orogenic erosion, and demonstrate that such a record is largely determined by high-fertility source rocks exposed within the drainage. Detrital thermochronology studies based on the lag-time approach should thus preferably include independent provenance discriminations and a full mineral fertility characterization of the potential source areas, in order to ensure a correct identification of the sediment sources and of the exogenic and endogenic processes monitored in the stratigraphic archive. Malusà M.G., Resentini A., Garzanti E., 2016. Hydraulic sorting and mineral fertility bias in detrital geochronology. Gondwana Res., 31, 1-19 Wittmann H., Malusà M.G., Resentini A., Garzanti E., Niedermann S., 2016. The cosmogenic record of mountain erosion transmitted across a foreland basin: Source-to-sink analysis of in situ 10Be, 26Al and 21Ne in sediment of the Po river catchment. Earth Planet. Sci. Lett. 452, 258-271

Fish scales in sediments from off Callao, central Peru

NASA Astrophysics Data System (ADS)

Díaz-Ochoa, J. A.; Lange, C. B.; Pantoja, S.; De Lange, G. J.; Gutiérrez, D.; Muñoz, P.; Salamanca, M.

2009-07-01

We study fish scales as a proxy of fish abundance and preservation biases together with phosphorus from fish remains (P fish) in a sediment core retrieved off Callao, Peru (12°1'S, 77°42'W; water depth=179 m; core length=52 cm). We interpret our results as a function of changing redox conditions based on ratios of redox-sensitive trace elements (Cu/Al, Mo/Al, Ni/Al, Zn/Al, V/Al), terrigenous indicators (Fe in clays, Ti, Al), and biogenic proxies (CaCO 3, biogenic opal, total nitrogen, organic carbon, barite Ba). The core covers roughly 700 years of deposition, based on 210Pb activities extrapolated downcore and 14C dating at selected intervals. Our fish-scale record is dominated by anchovy ( Engraulis ringens) scales followed by hake ( Merluccius gayii) scales. The core presented an abrupt lithological change at 17 cm (corresponding to the early 19th century). Above that depth, it was laminated and was more organic-rich (10-15% organic carbon) than below, where the core was partly laminated and less organic-rich (<10%). The lithological shift coincides with abrupt changes in dry bulk density and in the contents of terrigenous and redox-sensitive trace elements, biogenic proxies, and fish scales. The remarkable increase in redox-sensitive trace elements in the upper 17 cm of the core suggests more reducing conditions when compared with deeper and older horizons, and is interpreted as an intensification of the oxygen minimum zone off Peru beginning in the early 19th century. Higher fish-scale contents and higher P fish/P total ratios were also observed within the upper 17 cm of the core. The behavior of biogenic proxies and redox-sensitive trace elements was similar; more reduced conditions corresponded to higher contents of CaCO 3, C org, total nitrogen and fish scales, suggesting that these proxies might convey an important preservation signal.

Cycles of selected elements in the frame of Globalization and Global Change in the environment of Tenerife (Canary Islands, Spain)

NASA Astrophysics Data System (ADS)

Heidak, Markus O.; Glasmacher, Ulrich A.; Schöler, Heinfried; Trieloff, Mario; Kober, Bernd

2010-05-01

The Laurel Forest is an important and sensitive ecosystem with particular element cycling mechanisms. On Tenerife the distribution is straitened to some parts in the north, north-west and northeast. The NE trade wind ensures a permanently humid climate in the north. Major urban and industrial development is centred on Tenerife, and as a touristy hotspot the Island is exposed to heavy air traffic. Furthermore, the short distance to the African coastline and, therefore, to the Sahara, contribute a regular influence of African Dust emissions. In summary, Laurel Forest is exposed to different climatic conditions, variations in lithology and soils, and aerosols caused by local anthropogenic emissions, Saharan dust, and sea spray. The present study aims to understand geogenic and anthropogenic element transports of K, P, N, and organic components between soils and Laurel Forest. In addition, the element contribution from the aerosols such as the Sahara dust has to be quantified to understand the rock - soil - vegetation coupling system. The Sahara dust as one of the important aerosols has been studied by various researchers (Bustos et al., 1998; Rodrıguez, 1999; Torres et al., 2001; Viana et al., 2002). Viana et al.,(2002) quantified the impacts of African dust outbreaks for Tenerife and Gran Canaria, after the interpretation of the PM10 (thoracis particulate matter) from nineteen air quality monitoring stations. Three types of African dust contributions were identified and characterized (winter, summer and autumn-winter dust outbreaks). Collected samples with and without African dust influence proved that: (a) for the intensive winter African dust outbreaks (daily PM10 levels up to 191 mg/m3) at least 76% of the bulk PM10 levels may be attributable to dust load, whereas the anthropogenic input accounts for only 3-14% and (b) SiO2, Al2O3, Ca, K, Fe, Ti, V, Mn and Ba concentrations are excellent tracers of African origin (Viana et al., 2002).

Thermal Modeling of Al-Al and Al-Steel Friction Stir Spot Welding

NASA Astrophysics Data System (ADS)

Jedrasiak, P.; Shercliff, H. R.; Reilly, A.; McShane, G. J.; Chen, Y. C.; Wang, L.; Robson, J.; Prangnell, P.

2016-09-01

This paper presents a finite element thermal model for similar and dissimilar alloy friction stir spot welding (FSSW). The model is calibrated and validated using instrumented lap joints in Al-Al and Al-Fe automotive sheet alloys. The model successfully predicts the thermal histories for a range of process conditions. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Fe welds. Temperature predictions were used to study the evolution of hardness of a precipitation-hardened aluminum alloy during post-weld aging after FSSW.

Construction of inorganic elemental fingerprint and multivariate statistical analysis of marine traditional Chinese medicine Meretricis concha from Rushan Bay

NASA Astrophysics Data System (ADS)

Wu, Xia; Zheng, Kang; Zhao, Fengjia; Zheng, Yongjun; Li, Yantuan

2014-08-01

Meretricis concha is a kind of marine traditional Chinese medicine (TCM), and has been commonly used for the treatment of asthma and scald burns. In order to investigate the relationship between the inorganic elemental fingerprint and the geographical origin identification of Meretricis concha, the elemental contents of M. concha from five sampling points in Rushan Bay have been determined by means of inductively coupled plasma optical emission spectrometry (ICP-OES). Based on the contents of 14 inorganic elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, and Zn), the inorganic elemental fingerprint which well reflects the elemental characteristics was constructed. All the data from the five sampling points were discriminated with accuracy through hierarchical cluster analysis (HCA) and principle component analysis (PCA), indicating that a four-factor model which could explain approximately 80% of the detection data was established, and the elements Al, As, Cd, Cu, Ni and Pb could be viewed as the characteristic elements. This investigation suggests that the inorganic elemental fingerprint combined with multivariate statistical analysis is a promising method for verifying the geographical origin of M. concha, and this strategy should be valuable for the authenticity discrimination of some marine TCM.

Marine Biogeochemistry of Particulate Trace Elements in the Exclusive Economic Zone (eez) of the State of Qatar

NASA Astrophysics Data System (ADS)

Yigiterhan, O.; Al-Ansari, I. S.; Abdel-Moati, M.; Murray, J. W.; Al-Ansi, M.

2016-02-01

We focus on the trace element geochemistry of particulate matter in the Exclusive Economic Zone (EEZ) of Qatar. A main goal of this research was to analyze a complete suite of trace elements on particulate matter samples from the water column from different oceanographic biogeochemical zones of the EEZ around Qatar. The sample set also includes plankton samples which are the main source of biogenic particles, dust samples which are a source of abiological particles to surface seawater and surface sediments which can be a source of resuspended particles and a sink for settling particles. The 15 metals and 2 non-metals analyzed in this study will be Al, Ti, V, Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn, Mo, Ag, Ba, U and P, N. Many factors control the composition of trace elements in marine particles. Most of these are important in the EEZ of Qatar, including:1. Natural sources: These are rivers, atmospheric dust, sediment resuspension and leaks from oil beds. However, due to very limited rainfall rivers play no major role in Qatar but resuspension of shallow carbonate rich sediments and input of atmospheric dust are important due to strong currents and surrounding deserts.2. Adsorption/desorption: These chemical processes occur everywhere in the ocean and transfer metals between particles and the solution phase.3. Biological uptake: This process is likewise a universal ocean process and results in transport of metals from the solution phase to biological particles.4. Redox conditions: These are important chemical reactions in the oxic, suboxic and anoxic zones. This can be the dominant controlling mechanism in the northeastern hypoxic deeper waters of the Qatar EEZ.5. Anthropogenic sources: The eastern part of the Qatar contains numerous industrial sites, petroleum/gas platforms and refineries. There are numerous industrial sources but the main hot spots are the port of Doha and the industrial cities of Mesaieed, Khor Al-Odaid, and Ras Laffan. We aimed to determine the influence of the different current systems, water masses, and terrestrial inputs on the distribution, fractionation, and fate of trace metal contaminants and elemental pollutants. We have also observed the level of anthropogenic enrichments for some of the elements which have not been previously documented. This research should be viewed as the first stage of a complete study.

The Cultural Content in EFL Textbooks and What Teachers Need to Do about It (El contenido cultural en los textos de inglés y qué necesitan hacer los profesores al respecto)

ERIC Educational Resources Information Center

Gómez Rodríguez, Luis Fernando

2015-01-01

This article analyzes the cultural content in three communicative English as a foreign language textbooks that are used as main instructional resources in the English classroom. The study examined whether the textbooks include elements of surface or deep culture, and the findings indicate that the textbooks contain only static and congratulatory…

Social Moderation and Dynamic Elements in Crowdsourced Geospatial Data: A Report on Quality Assessment, Dynamic Extensions and Mobile Device Engagement in the George Mason University Geocrowdsourcing Testbed

DTIC Science & Technology

2015-11-01

GMU) Associate Professor Dieter Pfoser describes an explosion of user generated content (UGC) available over the Internet (Pfoser 2011, Crooks et al...Crowdsourced and User - Generated Geospatial Data,” Annual (Fairfax, VA: George Mason University, November 29, 2012), http://www.dtic.mil/dtic/tr/fulltext/u2...area include GPS-enabled geosocial and 34 Dieter Pfoser, “On User - Generated

Towards the Early Detection of Breast Cancer in Young Women

DTIC Science & Technology

2006-10-01

approach. 4. Poroelastic model for tissue deformation: We have implemented the model of Netti et al. in a finite element program in order to simulate...changes would not be expected. 44Interstitial Fluid Flow 5. Conclusions A poroelastic model that includes the effects of fluid flow and the possibility of...images to produce a displacement field. Using this displacement field, and an assumed linear elastic model for the tissue, an inverse problem is solved

Critical Assessment 14: High Entropy Alloys and Their Development as Structural Materials (Postprint)

DTIC Science & Technology

2015-01-01

Mn and Cu or on refractory metals such as V, Cr, Ti, Mo, Nb , Ta, W, Zr and Hf.5,6 The compound forming elements Al and Ti are often added to both...additional properties include environmental resistance , processibil- ity, appearance (for architectural uses) and low cost. Workhardening and solid...be successful, and some work already reports on the corrosion resistance , oxidation behaviour and wear properties of structural HEAs.5 High entropy

Configuring High Frequency Radar Observations in the Southern Chukchi Sea

DTIC Science & Technology

2013-02-24

latitude regions (e.g., Barth et al., 2010; Chavanne et al., 2007 ; Hisaki et al., 2001; Sentchev and Yaremchuk, 2007 ; Shay et al., 2008). During the...using the method of Köhl and Stammer (2004). Technically, this analysis is quite similar to the computation of the representative matrix elements that...et al., 2007 ). The model was configured on a spherical grid with a mean resolution of 10 km in the horizontal, and 11 vertical levels with spacing

Magnetism in icosahedral quasicrystals: current status and open questions

DOE PAGES

Goldman, Alan I.

2014-07-02

Progress in our understanding of the magnetic properties of R-containing icosahedral quasicrystals (R = rare earth element) from over 20 years of experimental effort is reviewed. This includes the much studied R-Mg-Zn and R-Mg-Cd ternary systems, as well as several magnetic quasicrystals that have been discovered and investigated more recently including Sc-Fe-Zn, R-Ag-In, Yb-Au-Al, the recently synthesized R-Cd binary quasicrystals, and their periodic approximants. In many ways, the magnetic properties among these quasicrystals are very similar. However, differences are observed that suggest new experiments and promising directions for future research.

Spatial characterization of dissolved trace elements and heavy metals in the upper Han River (China) using multivariate statistical techniques.

PubMed

Li, Siyue; Zhang, Quanfa

2010-04-15

A data matrix (4032 observations), obtained during a 2-year monitoring period (2005-2006) from 42 sites in the upper Han River is subjected to various multivariate statistical techniques including cluster analysis, principal component analysis (PCA), factor analysis (FA), correlation analysis and analysis of variance to determine the spatial characterization of dissolved trace elements and heavy metals. Our results indicate that waters in the upper Han River are primarily polluted by Al, As, Cd, Pb, Sb and Se, and the potential pollutants include Ba, Cr, Hg, Mn and Ni. Spatial distribution of trace metals indicates the polluted sections mainly concentrate in the Danjiang, Danjiangkou Reservoir catchment and Hanzhong Plain, and the most contaminated river is in the Hanzhong Plain. Q-model clustering depends on geographical location of sampling sites and groups the 42 sampling sites into four clusters, i.e., Danjiang, Danjiangkou Reservoir region (lower catchment), upper catchment and one river in headwaters pertaining to water quality. The headwaters, Danjiang and lower catchment, and upper catchment correspond to very high polluted, moderate polluted and relatively low polluted regions, respectively. Additionally, PCA/FA and correlation analysis demonstrates that Al, Cd, Mn, Ni, Fe, Si and Sr are controlled by natural sources, whereas the other metals appear to be primarily controlled by anthropogenic origins though geogenic source contributing to them. 2009 Elsevier B.V. All rights reserved.

Light, alpha, and Fe-peak element abundances in the galactic bulge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Christian I.; Rich, R. Michael; Kobayashi, Chiaki

2014-10-01

We present radial velocities and chemical abundances of O, Na, Mg, Al, Si, Ca, Cr, Fe, Co, Ni, and Cu for a sample of 156 red giant branch stars in two Galactic bulge fields centered near (l, b) = (+5.25,–3.02) and (0,–12). The (+5.25,–3.02) field also includes observations of the bulge globular cluster NGC 6553. The results are based on high-resolution (R ∼ 20,000), high signal-to-noise ration (S/N ≳ 70) FLAMES-GIRAFFE spectra obtained through the European Southern Observatory archive. However, we only selected a subset of the original observations that included spectra with both high S/N and that did notmore » show strong TiO absorption bands. This work extends previous analyses of this data set beyond Fe and the α-elements Mg, Si, Ca, and Ti. While we find reasonable agreement with past work, the data presented here indicate that the bulge may exhibit a different chemical composition than the local thick disk, especially at [Fe/H] ≳ –0.5. In particular, the bulge [α/Fe] ratios may remain enhanced to a slightly higher [Fe/H] than the thick disk, and the Fe-peak elements Co, Ni, and Cu appear enhanced compared to the disk. There is also some evidence that the [Na/Fe] (but not [Al/Fe]) trends between the bulge and local disk may be different at low and high metallicity. We also find that the velocity dispersion decreases as a function of increasing [Fe/H] for both fields, and do not detect any significant cold, high-velocity populations. A comparison with chemical enrichment models indicates that a significant fraction of hypernovae may be required to explain the bulge abundance trends, and that initial mass functions that are steep, top-heavy (and do not include strong outflow), or truncated to avoid including contributions from stars >40 M {sub ☉} are ruled out, in particular because of disagreement with the Fe-peak abundance data. For most elements, the NGC 6553 stars exhibit abundance trends nearly identical to comparable metallicity bulge field stars. However, the star-to-star scatter and mean [Na/Fe] ratios appear higher in the cluster, perhaps indicating additional self-enrichment.« less

No Martian soil component in shergottite meteorites

NASA Astrophysics Data System (ADS)

Barrat, J. A.; Jambon, A.; Ferrière, L.; Bollinger, C.; Langlade, J. A.; Liorzou, C.; Boudouma, O.; Fialin, M.

2014-01-01

We report on the major and trace element geochemistry of the impact melts contained in some shergottite meteorites. It has been previously proposed that some of these impact melts formed from a mixture of the host rock and a Martian soil component (e.g., Rao et al., 1999) or from partially weathered portions of the host rock (Chennaoui Aoudjehane et al., 2012). Our results contradict both of these theories. Trace element abundances of a glass pod from the EETA 79001A meteorite are identical to those of the host lithology, and indicate that no additional component is required in this case. The impact melts in Tissint share the same trace element features as the host rock, and no secondary phases produced by Martian secondary processes are involved. The light rare earth enrichments displayed by two small samples of Tissint (Chennaoui Aoudjehane et al., 2012) are possibly the result of some contamination of small stones on desert soil before the recovery of the meteorites.

Trace Element Cycling in Lithogenic Particles at Station ALOHA

NASA Astrophysics Data System (ADS)

Morton, P. L.; Weisend, R.; Landing, W. M.; Fitzsimmons, J. N.; Hayes, C. T.; Boyle, E. A.

2014-12-01

Trace element cycling in marine particles is influenced by atmospheric deposition, vertical export, biological uptake and remineralization, scavenging, and lateral transport processes. To investigate the cycling of lithogenic particles in the central North Pacific Ocean, surface and vertical profile samples of marine suspended particulate matter (SPM) were collected July-August 2012 during the HOE-DYLAN cruises at Station ALOHA. In the late summer, atmospheric dust inputs from the Gobi desert (which peak during the spring, April-May) were sparse, as indicated by low surface particulate Ti (pTi) concentrations. In contrast, surface pAl concentrations did not follow pTi trends as expected, but appear to be dominated by scavenging/uptake of dissolved Al during diatom blooms. Surface pMn concentrations were low, but vertical profiles of pMn and pMn/pTi reveal a strong sedimentary source at 200 m, originating from the Hawaiian continental shelf through a combination of redox mobilization and resuspension processes. The redox active elements Ce and Co can have chemistries similar to that of Mn, but in these samples the pCe and pCo distributions were distinct from Mn and each other in both surface trends and vertical profiles. Surface pREE (e.g., La, Ce, Pr) were highest during the earliest sampling events and quickly decreased to consistently low concentrations, while vertical distributions were characterized by scavenging onto biotic particles and mid-depth inputs. The surface particulate Co trend is similar to those of pAl and pP, while the pCo vertical profiles reflect surface enrichment but low concentrations and little variability at depth. A second, complementary poster is also being presented which examines the biological influence over particulate trace element cycling (Weisend et al., "Particulate Trace Element Cycling in a Diatom Bloom at Station ALOHA").

Trace elements and organic contaminants in stream sediments from the Red River of the North Basin

USGS Publications Warehouse

Brigham, M.E.; Tornes, L.H.

1996-01-01

To assess the presence and distribution of a variety of hydro-phobic chemicals in streams in the Red River of the North Basin, bottom sediments were analyzed for trace elements, organochlorines, and polycyclic aromatic hydrocarbons (PAHs). Glaciolacustrine clays and carbonate minerals are common in fine sediments of the region, and can help explain the distribution of many elements. Aluminum (Al), an indicator of glaciolacustrine clay minerals, correlates strongly (r>0.75, p<0.05) with Cr, Co, Fe, La, Li, K, Sc, and Ti; and moderately (0.55

Investigation of micrometre-sized fossil by laser mass spectrometer (LMS) designed for in situ space research

NASA Astrophysics Data System (ADS)

Tulej, Marek; Neubeck, Anna; Ivarsson, Magnus; Brigitte Neuland, Maike; Riedo, Andreas; Wurz, Peter

2015-04-01

Search for signatures of life on other planets is one of the most important goals of current planetary missions. Among various possible biomarkers, which can be investigated in situ on planetary surfaces, the detection of bio-relevant elements in planetary materials is of considerable interest and the abundance of isotopes can be important signatures of past and present bioactivities [1, 2]. We investigate the chemical composition of fossilised biological inclusions embedded in a carbonate host phase by a miniature laser ablation mass spectrometer (LMS) [3]. The LMS instrument combines a laser ablation ion source for ablation, atomisation and ionisation of surface material with a reflectron time-of-flight (TOF) mass spectrometer. LMS delivers mass spectra of almost all elements and their isotopes. In the current setup a fs-laser ablation ion source is applied with high lateral (15 um) and vertical (sub-um) resolution [4, 7] and the mass analyser supports mass resolution of 400-500 (at 56Fe mass peak) and dynamic range of eight orders of magnitude [5, 6]. From the 200 mass spectra recorded at 200 different locations on the carbonate sample surface, five mass spectra were identified which recorded the chemical composition of inclusions; from the other mass spectra the composition of the carbonate host matrix could be determined. The microscopic inspection of the sample surface and correlation with the coordinates of the laser ablation measurements made the confirmation to the location of the inclusion [8]. For the carbonate host matrix, the mass spectrometric analysis yielded the major elements H, C, O, Na, Mg, K and Ca and the trace elements Li, B and Cl. The measurements at the inclusion locations yielded in addition, the detection of F, Si, P, S, Mn, Fe, Ni, Co and Se. For most of the major elements the isotope ratios were found to be conform to the terrestrial values within a few per mills, while for minor and trace elements the determination of isotope ratios were less accurate due to low signal to noise ratios (SNR). The isotope abundances for the lightest isotope of B, S were observed to be larger than terrestrial, which is consistent with isotope fractionation by bio-relevant processes and a salty ocean. The studies demonstrates the current performance of the miniature LMS for in situ investigation of highly heterogeneous samples and its capabilities for the identification of fossilised biological matter. References: [1] Summons et al., Astrobiology, 11, 157, 2011. [2] Wurz et al., Sol. Sys. Res. 46 408, 2012. [3] Rohner et al.,Meas. Sci. Technol., 14, 2159, 2003. [4] Riedo et al., J. Anal. Atom. Spectrom. 28, 1256, 2013. [5] Riedo et al., J. Mass Spectrom.48, 1, 2013. [6] Neuland et al., Planet. Space. Sci. 101, 196, 2014. [7] Grimaudo et al., Anal. Chem. 2014, submitted. [8] Tulej et al. Geostand. Geoanal. Res., 2014; DOI: 10.1111/j.1751-908X.2014.00302.x

Atomistic Modeling of Nanostructures via the BFS Quantum Approximate Method

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Garces, Jorge E.; Noebe, Ronald D.; Farias, D.

2003-01-01

Ideally, computational modeling techniques for nanoscopic physics would be able to perform free of limitations on the type and number of elements, while providing comparable accuracy when dealing with bulk or surface problems. Computational efficiency is also desirable, if not mandatory, for properly dealing with the complexity of typical nano-strucured systems. A quantum approximate technique, the BFS method for alloys, which attempts to meet these demands, is introduced for the calculation of the energetics of nanostructures. The versatility of the technique is demonstrated through analysis of diverse systems, including multi-phase precipitation in a five element Ni-Al-Ti-Cr-Cu alloy and the formation of mixed composition Co-Cu islands on a metallic Cu(III) substrate.

Tungsten wire/FeCrAlY matrix turbine blade fabrication study

NASA Technical Reports Server (NTRS)

Melnyk, P.; Fleck, J. N.

1979-01-01

The objective was to establish a viable FRS monotape technology base to fabricate a complex, advanced turbine blade. All elements of monotape fabrication were addressed. A new process for incorporation of the matrix, including bi-alloy matrices, was developed. Bonding, cleaning, cutting, sizing, and forming parameters were established. These monotapes were then used to fabricate a 48 ply solid JT9D-7F 1st stage turbine blade. Core technology was then developed and first a 12 ply and then a 7 ply shell hollow airfoil was fabricated. As the fabrication technology advanced, additional airfoils incorporated further elements of sophistication, by introducing in sequence bonded root blocks, cross-plying, bi-metallic matrix, tip cap, trailing edge slots, and impingement inserts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels,more » cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.« less

The effect of environmentally friendly hot-dipping auxiliary on the morphology of alloy coatings

NASA Astrophysics Data System (ADS)

Chen, Suhong; Guo, Kai; Zhu, Yi; Gao, Feng; Han, Zhijun

2017-10-01

Zn-Al-Mg-RE hot-dip alloy coatings which prepared by the environmentally friendly plating auxiliary were investigated by X-ray diffraction (XRD), SEM analysis and salt spray measurement. Significant variation in coating surface morphology and element content are observed with increasing content of Al and Mg in this paper. A reinforced ternary eutectic Zn-Al-MgZn2 is confirmed which attribute to improvement metallographic structure derived from certain ternary eutectic reaction in alloy solidification. For Mg-containing coatings, the enhanced corrosion resistance is observed by corrosion resistance test in salt spray at 35°C with 5% NaCl in terms of corrosion weight changes. It is found that the incorporation of 3 wt.% Mg and 0.1 wt.% rare earth element in to Zn-Al-Mg-RE bath caused structural refinement of the crystal and also helped to achieve excellent surface morphology.

Advanced Mechanical Properties of a Powder Metallurgy Ti-Al-N Alloy Doped with Ultrahigh Nitrogen Concentration

NASA Astrophysics Data System (ADS)

Shen, J.; Chen, B.; Umeda, J.; Kondoh, K.

2018-03-01

Titanium and its alloys are recognized for their attractive properties. However, high-performance Ti alloys are often alloyed with rare or noble-metal elements. In the present study, Ti alloys doped with only ubiquitous elements were produced via powder metallurgy. The experimental results showed that pure Ti with 1.5 wt.% AlN incorporated exhibited excellent tensile properties, superior to similarly extruded Ti-6Al-4V. Further analysis revealed that its remarkably advanced strength could primarily be attributed to nitrogen solid-solution strengthening, accounting for nearly 80% of the strength increase of the material. In addition, despite the ultrahigh nitrogen concentration up to 0.809 wt.%, the Ti-1.5AlN sample showed elongation to failure of 10%. This result exceeds the well-known limitation for nitrogen (over 0.45 wt.%) that causes embrittlement of Ti alloys.

Geochemistry of komatiites and basalts from the Rio das Velhas and Pitangui greenstone belts, São Francisco Craton, Brazil: Implications for the origin, evolution, and tectonic setting

NASA Astrophysics Data System (ADS)

Verma, Sanjeet K.; Oliveira, Elson P.; Silva, Paola M.; Moreno, Juan A.; Amaral, Wagner S.

2017-07-01

The Neoarchean Rio das Velhas and Pitangui greenstone belts are situated in the southern São Francisco Craton, Minas Gerais, Brazil. These greenstone belts were formed between ca. 2.79-2.73 Ga, and consist mostly of mafic to ultramafic volcanics and clastic sediments, with minor chemical sediments and felsic volcanics that were metamorphosed under greenschist facies. Komatiites are found only in the Rio das Velhas greenstone belt, which is composed of high-MgO volcanic rocks that have been identified as komatiites and high-Mg basalts, based on their distinctive geochemical characteristics. The Rio das Velhas komatiites are composed of tremolite + actinolite + serpentine + albite with a relict spinifex-texture. The Rio das Velhas komatiites have a high magnesium content ((MgO)adj ≥ 28 wt.%), an Al-undepleted Munro-type [(Al2O3/TiO2)adj and (CaO/Al2O3)adj] ratio ranging from 27 to 47 and 0.48 to 0.89, relatively low abundances of incompatible elements, a depletion of light rare earth elements (LREE), a pattern of non-fractionated heavy rare- earth elements (HREE), and a low (Gd/Yb)PM ratio (≤ 1.0). Negative Ce anomalies suggest that alteration occurred during greenschist facies metamorphism for the komatiites and high-Mg basalts. The low [(Gd/Yb)PM < 1.0] and [(CaO/Al2O3)adj < 0.9)], high [(Al2O3/TiO2)adj > 18] and high HREE, Y, and Zr content suggest that the Rio das Velhas komatiites were derived from the shallow upper mantle without garnet involvement in the residue. The chemical compositions [(Al2O3/TiO2)adj, (FeO)adj, (MgO)adj, (CaO/Al2O3)adj, Na, Th, Ta, Ni, Cr, Zr, Y, Hf, and REE] indicate that the formation of the komatiites, high-Mg basalts and basalts occurred at different depths and temperatures in a heterogeneous mantle. The komatiites and high-Mg basalts melted at liquidus temperatures of 1450-1550 °C. The Pitangui basalts are enriched in the highly incompatible LILE (large-ion lithophile elements) relative to the moderately incompatible HFS (high field strength) elements. The Zr/Th ratio ranging from 76 to 213 and the relationship between the Nb/Th and Th/Yb ratios indicate that there is no crustal contamination in the Pitangui greenstone basalts. New multi-dimensional discrimination diagrams and conventional normalized multi-element diagrams indicate an island arc (IA) setting for the komatiites and high-Mg basalts from the Rio das Velhas and a mid ocean-ridge (MOR) to IA setting for the basalts from the Pitangui greenstone belts.

Method For Making Electronic Circuits Having Nial And Ni3al Substrates

DOEpatents

Deevi, Seetharama C.; Sikka, Vinod K.

2001-01-30

A method for making electronic circuit component having improved mechanical properties and thermal conductivity comprises steps of providing NiAl and/or Ni.sub.3 Al, and forming an alumina layer thereupon prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

Multiscale Concrete Modeling of Aging Degradation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammi, Yousseff; Gullett, Philipp; Horstemeyer, Mark F.

In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Ginermore » et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].« less

Major factors influencing the elemental composition of surface estuarine sediments: the case of 15 estuaries in Portugal.

PubMed

Mil-Homens, M; Vale, C; Raimundo, J; Pereira, P; Brito, P; Caetano, M

2014-07-15

Upper sediments (0-5 cm) were sampled in 94 sites of water bodies of the fifteen Portuguese estuaries characterized by distinct settings of climate, topography and lithology, and marked by diverse anthropogenic pressures. Confined areas recognized as highly anthropogenic impacted, as well as areas dominated by erosion or frequently dredged were not sampled. Grain size, organic carbon (Corg), Al and trace elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn) were determined. Normalisation of trace element concentrations to Al and Corg, correlations between elements and Principal Component Analysis (PCA) allowed identifying elemental associations and the relevance of grain-size, lithology and anthropogenic inputs on sediment chemical composition. Whereas grain-size is the dominant effect for the majority of the studied estuaries, the southern estuaries Mira, Arade and Guadiana are dominated by specific lithologies of their river basins, and anthropogenic effects are identified in Ave, Leça, Tagus and Sado. This study emphasizes how baseline values of trace elements in sediments may vary within and among estuarine systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

Finite element simulation of texture evolution and Swift effect in NiAl under torsion

NASA Astrophysics Data System (ADS)

Böhlke, Thomas; Glüge, Rainer; Klöden, Burghardt; Skrotzki, Werner; Bertram, Albrecht

2007-09-01

The texture evolution and the Swift effect in NiAl under torsion at 727 °C are studied by finite element simulations for two different initial textures. The material behaviour is modelled by an elastic-viscoplastic Taylor model. In order to overcome the well-known shortcomings of Taylor's approach, the texture evolution is also investigated by a representative volume element (RVE) with periodic boundary conditions and a compatible microstructure at the opposite faces of the RVE. Such a representative volume element takes into account the grain morphology and the grain interaction. The numerical results are compared with experimental data. It is shown that the modelling of a finite element based RVE leads to a better prediction of the final textures. However, the texture evolution path is not accounted for correctly. The simulated Swift effect depends much more on the initial orientation distribution than observed in experiment. Deviations between simulation and experiment may be due to continuous dynamic recrystallization.

Assessment of the factors affecting protective alumina formation under hot corrosion conditions

NASA Astrophysics Data System (ADS)

Task, Michael Nathan

In this study, the influence of microstructure, composition, and phase constitution on the Type I (900°C) and Type II (700°C) hot corrosion resistance of MCrAlY and β-NiAl base alloys was investigated. The Type II hot corrosion resistance of MCrAlY alloys is generally enhanced by microstructural refinement. This can be attributed to the more rapid establishment of a protective Al2O3-rich scale due to the higher density of short-circuit diffusion paths for Al (phase boundaries). However, it was shown that for a given bulk composition, the compositions of the individual phases is also extremely important. If one phase is lean in an element which is highly beneficial from a hot corrosion standpoint, e.g., Cr, Type II hot corrosion resistance is quite poor, regardless of the microstructural scale. In addition, coarse reactive-element-rich phases, which are commonly found in MCrAlY alloys, can be incorporated into the thermally grown Al2O 3 scale and act as initiation sites for Type II attack. This stresses the importance of reactive element content and distribution in MCrAlY coatings. During Type I hot corrosion exposure of β-Ni-36Al (at. %) base alloys, the incubation stage is greatly extended by the addition of 5% Pt, Co, or Cr. In each case, the beneficial effects can be linked to an enhanced ability to rapidly form a protective Al2O3 scale, and to heal this scale when it sustains damage during exposure. With regard to Type II hot corrosion, individual additions of 5 at. % Pt or Cr are beneficial, largely for the same reason; however, additions of 5 at. % Co and co-additions of 5 at. % Pt + 5 at. % Cr result in a decrease in the duration of the incubation stage. Subsurface phase transformations that occur in the latter systems prevent the alloy from maintaining the growth of the Al2O3 scale. This mechanism is discussed in detail. Finally, the influence of alloy composition and exposure environment on the kinetics of the θ→α Al2O3 transformation in scales grown on β-NiAl alloys at 900°C was thoroughly investigated. The relative importance of the kinetics of this transformation during Type I hot corrosion exposure is discussed.

Elemental Fractionation During Rapid Accretion of the Moon Triggered by a Giant Impact

NASA Technical Reports Server (NTRS)

Abe, Y.; Zahnle, K. J.; Hashimoto, A.

1998-01-01

Recently, Ida et al. made an N-body simulation of lunar accretion from a protolunar disk formed by a giant impact. One of their important conclusions is that the accretion time of the Moon is as short as one month. Such rapid accretion is a necessary consequence of the high surface density of a lunar mass disk accreting just beyond the Roche limit (about 3Re); the Safronov accretion time (a few days) is even shorter. The energy of accretion always exceeds the gravitational binding energy of newly arriving matter. Hence, without an energy sink, the accreting body is thermally unstable. For the Earth and other planets, radiation acts as the sink. However, in such a short accretion time, the Moon cannot radiate the accretional energy. Even radiating at a silicate cloudtop temperature of roughly 2000 K, it would take more than 100 yr to radiatively cool the Moon. The plausible alternative heat sinks are heat capacity, latent heat of vaporization, and thermal escape of the gas to space (i.e., hydrodynamic blowoff). The latter becomes plausible for the Moon because the scale height at 2000 K (about 300 km) is a significant fraction of the lunar radius. The early stages of lunar (or "lunatesimal") growth release relatively little energy and can occur simply by heating the material, especially if the accreting material is originally cold. However, the material is unlikely to be cold, because the disk itself is hot and cooling time is long, while the lunar accretion time iss very short. Therefore, the moon is likely to accrete condensed material just after it condenses. Accordingly, the newly accreted material will be on the verge of vaporization and will have very little heat capacity to spare. The immediate heat sink is the latent heat of vaporization. Most of the vapor will escape from the moon, because the thermal energy in the gas can be used to drive escape. However, vaporization is generally incomplete. the latent heat of vaporization exceeds the energy of accretion. Viewed globally, the accretional energy is about half the energy required to vaporize the entire Moon. Thus to first approximation, half of the Moon-forming material can be vaporized and lost during accretion. During this process, we would expect preferential loss of relatively volatile elements. Escape will retard the rate of accretion. To test these ideas, we computed detailed models of the thermal state of the Moon during accretion. We pay special attention to the structure of the silicate atmosphere and its loss rate by calculating the chemical species at equilibrium. We used the PHEQ program which includes 12 elements (H,O,C,Mg,Si,Fe,Ca, Al, Na,Ti, and N.) and 272 compounds (including ionic compounds). Because of the large heats of vaporization and ionization, the adiabatic atmosphere is nearly isothermal and massive escape is expected. The pressure of the atmosphere is determined by the balance between vaporization of a accreting material and escape. If the accretion time is one month, a 0.3 bar atmosphere is expected. Elemental fractionation depends strongly on the temperature of the accreting material. The initial temperature of the material can be estimated from the condition of gravitational instability in the protolunar disk. As shown by Ida et al, accretion starts when gravitational instability occurs when more than 99% of the material condenses. At this point, all of Ca, Al, Si, Mg, and Fe, and 95% of Na (probably K also), are in condensed phases. If the moon is formed from the accretion of such material, volatile elements such as Na, and K are retained by the moon only early in accretion. At later times, K and Na are lost and a fraction of the MG, Si and Fe is lost. However, refractory elements such as Ca and Al are retained and so achieve a mild degree (factor 2) of superabundance.

A new model of physical evolution of Jupiter-family comets

NASA Astrophysics Data System (ADS)

Rickman, H.; Szutowicz, S.; Wójcikowski, K.

2014-07-01

We aim to find the statistical physical lifetimes of Jupiter Family comets. For this purpose, we try to model the processes that govern the dynamical and physical evolution of comets. We pay special attention to physical evolution; attempts at such modelling have been made before, but we propose a more accurate model, which will include more physical effects. The model is tested on a sample of fictitious comets based on real Jupiter Family comets with some orbital elements changed to a state before the capture by Jupiter. We model four different physical effects: erosion by sublimation, dust mantling, rejuvenation (mantle blow-off), and splitting. While for sublimation and splitting there already are some models, like di Sisto et. al. (2009), and we only wish to make them more accurate, dust mantling and rejuvenation have not been included in previous, statistical physical evolution models. Each of these effects depends on one or more tunable parameters, which we establish by choosing the model that best fits the observed comet sample in a way similar to di Sisto et. al. (2009). In contrast to di Sisto et. al., our comparison also involves the observed active fractions vs. nuclear radii.

(abstract) Transmission Electron Microscopy of Al(sub x)Ga(sub 1-x)N/SiC Multilayer Structures Grown on Sapphire Substrates

NASA Technical Reports Server (NTRS)

Pike, W. T.; George, T.; Khan, M. A.; Kuznia, J. N.

1994-01-01

The potential of wide-band-gap III-V nitrides as ultraviolet sensors and light emitters has prompted an increasing amount of work recently, including the fabrication of the first UV sensors from as-deposited single crystal GaN. We have used high resolution transmission electron microscopy (TEM) to study the microstructure of two novel developments of wide-band-gap III-V nitrides: the growth of ultra-short period GaN/AlN superlattices; and the incorporation of SiC layers into Al(sub x)Ga(sub 1-x)N structures. By varying the relative periods in a GaN/AlN superlattice, the band gap of the composite can be tailored to lie between the elemental values of 365 nm for GaN and 200 nm for AlN. The group IV semiconductor, SiC, has a wide band-gap and has a close lattice match (less than 3 %) to Al(sub x)Ga(sub 1-x)N for growth on the basal plane. Demonstration of epitaxial growth for Al(sub x)Ga(sub 1-x)N/SiC multilayers would introduce a wide band-gap analog to the already existing family of III-V and Si(sub 1-x)Ge(sub x) heteroepitaxial growth systems. Although good quality growth of GaN on SiC substrates has been demonstrated, Al(sub x)Ga(sub 1-x)N/SiC multilayer structures have never been grown and the interfacial structure is unknown.

First principle study of AlX (X=3d, 4d, 5d elements and Lu) dimer.

PubMed

Ouyang, Yifang; Wang, Jianchuan; Hou, Yuhua; Zhong, Xiaping; Du, Yong; Feng, Yuanping

2008-02-21

The ground state equilibrium bond length, harmonic vibrational frequency, and dissociation energy of AlX (X=3d,4d,5d elements and Lu) dimers are investigated by density functional method B3LYP. The present results are in good agreement with the available experimental and other theoretical values except the dissociation energy of AlCr. The present calculations show that the late transition metal can combine strongly with aluminum compared with the former transition metal. The present calculation also indicates that it is more reasonable to replace La with Lu in the Periodic Table and that the bonding strengths of zinc, cadmium, and mercury with aluminum are very weak.

Investigation of the Influence of Selected Soil and Plant Properties from Sakarya, Turkey, on the Bioavailability of Trace Elements by Applying an In Vitro Digestion Model.

PubMed

Altundag, Huseyin; Albayrak, Sinem; Dundar, Mustafa S; Tuzen, Mustafa; Soylak, Mustafa

2015-11-01

The main aim of this study was an investigation of the influence of selected soil and plant properties on the bioaccessibility of trace elements and hence their potential impacts on human health in urban environments. Two artificial digestion models were used to determine trace element levels passing from soil and plants to man for bioavailability study. Soil and plant samples were collected from various regions of the province of Sakarya, Turkey. Digestive process is started by addition of soil and plant samples to an artificial digestion model based on human physiology. Bioavailability % values are obtained from the ratio of the amount of element passing to human digestion to element content of soil and plants. According to bioavailability % results, element levels passing from soil samples to human digestion were B = Cr = Cu = Fe = Pb = Li < Al < Ni < Co < Ba < Mn < Sr < Cd < Na < Zn < Tl, while element levels passing from plant samples to human digestion were Cu = Fe = Ni = Pb = Tl = Na = Li < Co < Al < Sr < Ba < Mn < Cd < Cr < Zn < B. It was checked whether the results obtained reached harmful levels to human health by examining the literature.

Mechanical characterization of hybrid and functionally-graded aluminum open-cell foams with nanocrystalline-copper coatings

NASA Astrophysics Data System (ADS)

Sun, Yi

Cellular/foam materials found in nature such as bone, wood, and bamboo are usually functionally graded by having a non-uniform density distribution and inhomogenous composition that optimizes their global mechanical performance. Inspired by such naturally engineered products, the current study was conducted towards the development of functionally graded hybrid metal foams (FGHMF) with electrodeposited (ED) nanocrystalline coatings. First, the deformation and failure mechanisms of aluminum/copper (Al/Cu) hybrid foams were investigated using finite element analyses at different scales. The micro-scale behavior was studied based on single ligament models discretized using continuum elements and the macro-scale behavior was investigated using beam-element based finite element models of representative unit volumes consisting of multiple foam cells. With a detailed constitutive material behavior and material failure considered for both the aluminum ligament and the nano-copper coating, the numerical models were able to capture the unique behavior of Al/Cu hybrid foams, such as the typically observed sudden load drop after yielding. The numerical models indicate that such load drop is caused by the fracture of foam ligaments initiated from the rupture of the ED nano-copper coating due to its low ductility. This failure mode jeopardizes the global energy absorption capacity of hybrid foams, especially when a thick coating is applied. With the purpose of enhancing the performance of Al/Cu hybrid foams, an annealing process, which increased the ductility of the nanocrystalline copper coating by causing recovery, recrystallination and grain growth, was introduced in the manufacturing of Al/Cu hybrid foams. Quasi-static experimental results indicate that when a proper amount of annealing is applied, the ductility of the ED copper can be effectively improved and the compressive and tensile behavior of Al/Cu hybrid foams can be significantly enhanced, including better energy absorption capacity. The behavior of Al/Cu hybrid foams under high-strain-rate condition was then investigated using experiments on a split Hopkinson pressure bar. It was found that the ED nano-copper coating can also effectively enhance the energy absorption capacities of aluminum open-cell foams under high strain rate. Similar to the quasi-static behavior, a large stress drop was observed in the compressive response of Al/Cu hybrid foams under high strain rate, which was accompanied by dramatic shattering of material. It is shown that a more ductile behavior and better energy absorption performance under high strain rate condition can be also obtained by introducing an annealing process. Finally, the manufacturing process of Al/Cu hybrid foams was customized to fabricate FGHMF systems with two dimensional property gradients. The performance of these FGHMFs at both quasi-static and dynamic conditions was evaluated. Under quasi-static condition, two flexural type loading conditions were considered, namely, a three point bending condition and a cantilever beam condition. The dynamic behavior of FGHMFs was investigated by conducting drop weight tower tests on a three point bending setup. It was found that the failure mechanism of hybrid metal foams can be modified and the mechanical properties, such as stiffness and strength, and energy absorption capacities of hybrid metal foams can be optimized under both quasi-static and dynamic conditions by introducing strategically designed coating patterns. The presented novel approach and findings in this study provide valuable information on the development of high performance hybrid and functionally-graded cellular materials.

Chemical abundances and kinematics of TYC 5619-109-1

NASA Astrophysics Data System (ADS)

Pereira, C. B.; Smith, V. V.; Drake, N. A.; Roig, F.; Hasselquist, S.; Cunha, K.; Jilinski, E.

2017-07-01

Previous determinations of chemical abundances of the metal-poor red giant TYC 5619-109-1, derived via high-resolution near-infrared spectra from the Apache Point Observatory Galactic Evolution Experiment survey, indicate that this star is strongly enriched in the elements N and Al. Here, we obtain and analyse high-resolution optical spectra of TYC 5619-109-1 to verify these large N and Al overabundances and to measure abundances of a wider range of chemical elements. Our analysis confirms the N- and Al-rich nature of this star, and shows that the abundances of the s-process elements are also strongly enhanced, particularly in the heavy second s-process peak elements (Ba, La, Ce, Nd). Lighter s-process elements (Y, Zr) show smaller overabundances, and the ratio of the light-to-heavy s-process elements is consistent with the 13C(α, n)16O neutron source operating in a low-metallicity environment. The lack of Tc I lines and the abundance of Nb compared to Zr indicate that this red giant is probably not a thermally pulsing asymptotic giant branch (TP-AGB) star. Mass transfer from a former s-process-rich TP-AGB companion may produce the observed overabundances, but our radial velocity analysis provides no evidence that TYC 5619-109-1 is a binary with a white dwarf companion. We suggest that TYC 5619-109-1 formed from gas already strongly enriched in s-process elements, as found in many dwarf galaxies and globular clusters. A dynamical analysis reveals that there is only a small probability that TYC 5619-109-1 is an escaped member of a globular cluster, and in this case the most likely candidate would be ω Cen.

Elemental Gains/Losses Associated with Alteration Fractures in an Eolian Sandstone, Gale Crater, Mars

NASA Technical Reports Server (NTRS)

Ming, D. W.; Yen, A. S.; Gellert, R.; Sutter, B.; Berger, J. A.; Thompson, L. M.; Schmidt, M. E.; Morris, R. V.; Treiman, A. H.

2016-01-01

The Mars Science Laboratory rover Curiosity has traversed up section through approximately 100 m of sedimentary rocks deposited in fluvial, deltaic, lacustrine, and eolian environments (Bradbury group and overlying Mount Sharp group). The Stimson formation unconformably overlies a lacustrine mudstone at the base of the Mount Sharp group and has been interpreted to be a cross-bedded sandstone of lithified eolian dunes. Unaltered Stimson sandstone has a basaltic composition similar to the average Mars crustal composition, but is more variable and ranges to lower K and higher Al. Fluids passing through alteration "halos" adjacent to fractures have altered the chemistry and mineralogy of the sandstone. Elemental mass gains and losses in the alteration halos were quantified using immobile element concentrations, i.e., Ti (taus). Alteration halos have elemental gains in Si, Ca, S, and P and large losses in Al, Fe, Mn, Mg, Na, K, Ni, and Zn. Mineralogy of the altered Stimson is dominated by Ca-sulfates, Si-rich X-ray amorphous materials along with plagioclase feldspar, magnetite, and pyroxenes. The igneous phases were less abundant in the altered sandstone with a lower pyroxene/plagioclase feldspar. Large elemental losses suggest acidic fluids initially removed these elements (Al mobile under acid conditions). Enrichments in Si, Ca, and S suggest secondary fluids (possibly alkaline) passed through these fractures leaving behind X-ray amorphous Si and Ca-sulfates. The mechanism for the large elemental gains in P is unclear. The geochemistry and mineralogy of the altered sandstone suggests a complicated diagenetic history with multiple episodes of aqueous alteration under a variety of environmental conditions (e.g., acidic, alkaline).

Ordinary Stoichiometry of Extraordinary Microbes

NASA Astrophysics Data System (ADS)

Neveu, M.; Poret-Peterson, A. T.; Anbar, A. D.; Elser, J. J.

2013-12-01

Life on Earth seems to be composed of the same chemical elements in relatively conserved stoichiometric proportions. However, this observation is largely based on observations of biota from habitats spanning a moderate range of temperature and chemical composition (e.g., temperate lakes, forests, grasslands, oceanic phytoplankton). Whether this stoichiometry is conserved in settings that differ radically from such "normal" planetary settings may provide insight into the habitability of environments with radically different stoichiometries, and into possible stoichiometries for putative life beyond Earth. Here we report the first measurements of elemental stoichiometries of microbial extremophiles from hot springs of Yellowstone National Park (YNP). These phototrophic and chemotrophic microbes were collected in locations spanning large ranges of temperature (ambient to boiling) and pH (1 to 9). Microbial biomass was carefully extracted from hot spring sediment substrata following a procedure adapted from [1], which conserves cellular elemental abundances [2]. Their C and N contents were determined by Elemental Analysis Isotope Ratio Mass Spectrometry, and their P and trace element (Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, and non-biogenic Al and Ti) contents were measured by Inductively Coupled Plasma Mass Spectrometry. Residual mineral contamination was an issue in some samples with low measured C and N; we eliminated these from our results. Even in the remaining samples, contamination sometimes prevented accurate determinations of cellular Mg, Ca, Mn, and Fe abundances; however, the cellular Ni, Cu, Zn, and Mo contents were several-fold above contamination level. Although hot spring water and sediment elemental abundances varied by orders of magnitude, the data showed that the extremophiles have a major and trace element stoichiometry similar to those previously measured in "normal" microbial biomass [3-6]. For example, biomass C:N:P ratios resembled those commonly observed in temperate lakes (e.g., C:P ratios of 260 to 1600 and N:P ratios of 35 to 200) while cellular C:Fe ratios were of a similar magnitude to those of marine phytoplankton. Exceptions were Al and Ti, much higher than previously measured, likely because of contamination from residual sediment. Moreover, the low phosphorus contents (high C:P and N:P ratios) are suggestive of limited P supply. Chemotrophs and phototrophs had similar elemental compositions to one another, although Mg, Mn, Ni, and Zn abundances were higher and nearly constant in phototrophs, due to their importance in phototrophic metabolism. Despite the tremendous physical and chemical diversity of YNP environments, the stoichiometry of life in these settings is surprisingly ordinary. Thus, our study supports the view that the biological stoichiometry of life is heavily constrained by the elemental composition of core biomolecules, and that even life in extreme environments must operate within these constraints. In the frame of life detection in exotic locales, these results suggest a general elemental biosignature for life as we know it. References: [1] Amalfitano and Fazi. 2008. J. Microbiol. Meth. 75:237 [2] Neveu et al. L&O: Meth., in review [3] Ho et al. 2003. J. Phycol. 39:1145 [4] Nuester et al. 2012. Front. Microbiol. 3:150 [5] Sterner and Elser. 2002. Ecological Stoichiometry. Princeton U. Press [6] Twining et al. 2011. Deep-Sea Res. II 58:325

High temperature properties of non-critical Fe-Al alloys doped by non critical or “slightly–critical” elements

NASA Astrophysics Data System (ADS)

Vodičková, Věra; Hanus, Pavel; Vlasák, Tomáš; Švec, Martin

2018-03-01

Iron aluminides were developed as an alternative to stainless steels after World War II. The main intended impact was to save strategic elements (chromium or nickel). The result of these investigations was development of registered alloys as Pyroferal (Czechoslovak Republic), Thugal (Soviet Union) or Thermagal (France). The investigation of these type alloys continued in the nineties thanks to technological progress. In this time iron aluminides seems to be promising material with very good corrosive and environment resistivity. The mechanical properties of binary iron aluminides (Fe-Al) are average at higher temperatures but strengthening effect of alloying elements is significant. The aim of the article is to show influence of non-critical additives (such as C, Ti, Zr) and also “slightly critical” elements as e.g. Ce, Nb on high temperature creep properties of alloys.

Geochemistry and Minerality of Wine

NASA Astrophysics Data System (ADS)

Oze, C.; Horton, T. W.; Beaman, M.

2010-12-01

Kaolinite (Al2Si2O5(OH)4) and gibbsite (Al(OH)3) are capable of forming in a variety of environments including anthropogenic solutions such as wine. Here, we evaluate the geochemistry of twelve white wines in order to assess the potential relationship between kaolinite/gibbsite saturation and minerality, a common wine descriptor used to express the rock and/or soil character in the aromas and flavors of wines. Aluminum and Si concentrations ranged from 228-1,281 µg L-1 and 6,583-19,746 µg L-1, respectively, where Si and Al are the only elements to demonstrate positive covariance with minerality scores. Sulfur levels varied from 25,013-167,383 µg L-1 and show the strongest negative covariance with minerality scores. However, like all of the elements studied (Al, Si, Na, Mg, S, K, Ca, and Fe), these trends were not significantly different than random at the 95% confidence level. In contrast, the relative degrees of gibbsite/kaolinite saturation display strong positive covariance with minerality scores and these trends are not random at the greater than 95% confidence level. Overall, our tasters were able to accurately assess the degree of gibbsite/kaolinite saturation amongst the twelve wines based on the objective of assessing minerality. Although the wines were undersaturated with respect to gibbsite/kaolinite, geochemical modeling reveals that increasing the wines’ pHs from ~3.3 to 4.1-4.6 (which is achievable on the palate where saliva has a pH of 7.4) results in gibbsite/kaolinite oversaturation. By considering that minerality is a function of gibbsite/kaolinite saturation and decreasing S, the origin of minerality’s taste and chemical origin in wine with known physical standards becomes increasingly crystalline.

Release of Si from Silicon, a Ferrosilicon (FeSi) Alloy and a Synthetic Silicate Mineral in Simulated Biological Media

PubMed Central

Herting, Gunilla; Jiang, Tao; Sjöstedt, Carin; Odnevall Wallinder, Inger

2014-01-01

Unique quantitative bioaccessibility data has been generated, and the influence of surface/material and test media characteristics on the elemental release process were assessed for silicon containing materials in specific synthetic body fluids at certain time periods at a fixed loading. The metal release test protocol, elaborated by the KTH team, has previously been used for classification, ranking, and screening of different alloys and metals. Time resolved elemental release of Si, Fe and Al from particles, sized less than 50 µm, of two grades of metallurgical silicon (high purity silicon, SiHG, low purity silicon, SiLG), an alloy (ferrosilicon, FeSi) and a mineral (aluminium silicate, AlSi) has been investigated in synthetic body fluids of varying pH, composition and complexation capacity, simple models of for example dermal contact and digestion scenarios. Individual methods for analysis of released Si (as silicic acid, Si(OH)4) in synthetic body fluids using GF-AAS were developed for each fluid including optimisation of solution pH and graphite furnace parameters. The release of Si from the two metallurgical silicon grades was strongly dependent on both pH and media composition with the highest release in pH neutral media. No similar effect was observed for the FeSi alloy or the aluminium silicate mineral. Surface adsorption of phosphate and lactic acid were believed to hinder the release of Si whereas the presence of citric acid enhanced the release as a result of surface complexation. An increased presence of Al and Fe in the material (low purity metalloid, alloy or mineral) resulted in a reduced release of Si in pH neutral media. The release of Si was enhanced for all materials with Al at their outermost surface in acetic media. PMID:25225879

Evaluation of metal ion release from Ti6Al4V and Co-Cr-Mo casting alloys: in vivo and in vitro study.

PubMed

El Sawy, Amal A; Shaarawy, Mohammed A

2014-02-01

The aim of this study was to evaluate the amount of ions released from Ti6Al4V and Co-Cr-Mo alloys both in vivo and in vitro. Twenty-one discs of each alloy were constructed and divided into seven groups. Three specimens from each group were immersed in a buffered saline solution over a period of 1, 3, 5, 7, 14, 21, and 28 days. Twenty-eight participants were also included in the study, where the study group consisted of 14 mandibular partially edentulous patients, and the control group consisted of 14 volunteers. The study group was further divided into two equal groups: the first group received removable partial dentures (RPDs) constructed from Co-Cr-Mo alloy, while the second group received RPDs constructed from Ti6Al4V alloy. Saliva samples were collected from each participant over the same study period. The conditioning media and saliva samples were analyzed using a spectrophotometer. One-way ANOVA and Tukey tests were used for statistical analysis (p < 0.05). The concentrations of metal ions released from the studied alloys were significantly higher in the in vitro than in the in vivo study group during the follow-up periods. A statistically significant increase in ion concentrations of the different elements for both alloys was found with time (p < 0.05). The amounts of released metallic ions from Co-Cr-Mo and Ti6Al4V alloys were higher in the buffered saline solutions than in the studied saliva samples and control groups; however, these amounts were still within the physiological limit of trace elements in the human body. © 2013 by the American College of Prosthodontists.

Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

NASA Astrophysics Data System (ADS)

Chen, M.; Kocar, B. D.

2016-12-01

Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).

Characterisation of a complex thin walled structure fabricated by selective laser melting using a ferritic oxide dispersion strengthened steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boegelein, Thomas, E-mail: t.boegelein@liv.ac.uk; Louvis, Eleftherios; Dawson, Karl

2016-02-15

Oxide dispersion strengthened (ODS) alloys exhibit superior mechanical and physical properties due to the presence of nanoscopic Y(Al, Ti) oxide precipitates, but their manufacturing process is complex. The present study is aimed at further investigation of the application of an alternative, Additive Manufacturing (AM) technique, Selective Laser Melting (SLM), to the production of consolidated ODS alloy components. Mechanically alloyed PM2000 (ODS-FeCrAl) powders have been consolidated and a fine dispersion of Y-containing precipitates were observed in an as built thin-walled component, but these particles were typically poly-crystalline and contained a variety of elements including O, Al, Ti, Cr and Fe. Applicationmore » of post-build heat treatments resulted in the modification of particle structures and compositions; in the annealed condition most precipitates were transformed to single crystal yttrium aluminium oxides. During the annealing treatment, precipitate distributions homogenised and localised variations in number density were diminished. The resulting volume fractions of those precipitates were 25–40% lower than have been reported in conventionally processed PM2000, which was attributed to Y-rich slag-like surface features and inclusions formed during SLM. - Highlights: • A wall structure was grown from ODS steel powder using selective laser melting. • A fine dispersion of nano-precipitates was apparent in as-build material. • Precipitates were multi-phased containing several elements, e.g. O, Ti, Al, Fe, Cr, Y. • Post-build annealing changed those into typically single-crystalline Y–Al–O. • The anneal also reduced and stabilised the volume fraction of precipitates to ~ 0.006.« less

Trace elements concentration and distributions in coal and coal mining wastes and their environmental and health impacts in Shaanxi, China.

PubMed

Hussain, Rahib; Luo, Kunli; Chao, Zhao; Xiaofeng, Zhao

2018-05-07

This study probe the probable impacts of coal mining pollution and its impacts on human's health and environment. A total of 144 samples including coal and coal wastes, soil, plants, foods, and water were collected from the Hancheng county and countryside of Shaanxi, China. All the samples were analyzed for trace elements using ICP-MS, OES, and AFS. Results showed that the concentration of Se, As, Cr, Cu, Pb, Cd, Co, Ni, Mo, U, Th (mgKg -1 ), Fe, Mn, Al, Ti (%) etc., in coal and coal wastes were 7.5, 12.1, 275, 55, 54.2, 0.8, 14.8, 94.5, 8.9, 4.9, 17.2, 3.5, 0.02, 19, 0.7, respectively. While in soil 0.6, 12, 194, 27.5, 7.4, 0.6, 11.3, 83.4, 0.7, 1.7, 9.9, 3.1, 0.04, 10.5, and 0.4 for the above elements, respectively. In Hancheng foods, the average concentration of Se-0.09, As-0.15, Cr-1.8, Cu-3.2, Pb-0.4, Cd-0.02, Co-0.09, Ni-0.4, Mo-0.64, U-0.01, Th-0.03, Fe-129, Mn-15.6, Al-234, and Ti-5.2 in mgKg -1 , respectively, which are comparably higher than the countryside. The elemental concentration in groundwater of both areas was below the WHO-2004 standard. In Hancheng, the average daily intake (mgKg -1 bw/d) of Se 0.004-0.0038, As 0.004-0.13, Cr 0.055-0.06, Cd 0.001-0.004, Ni 0.018-13.91, Pb 0.05-0.001 adult-children, respectively. The toxic trace elements such as Cr, Cu, Mn, Pb, Ti, Cd, Co, Th, Fe, Al, and Mo caused non-carcinogenic risk with high morbidity in children than adults. By assessing environmental risks, coal and coal wastes caused high risk, food and plants faced moderate to high risk, while mountain and agriculture soil are prone to low to considerable risk. The pollution in Hancheng County is extreme as compared to the countryside. The study concluded that the contamination is geogenic in both the areas but coal mining enhance the metals contamination and has extensive impacts on the living community and environment of Hancheng areas.

Artificial topography changes the growth strategy of Spartina alterniflora, case study with wave exposure as a comparison.

PubMed

Hong, Hualong; Dai, Minyue; Lu, Haoliang; Liu, Jingchun; Zhang, Jie; Chen, Chaoqi; Xia, Kang; Yan, Chongling

2017-11-17

This paper reports findings about the growth of Spartina alterniflora (Loisel.) near an engineered coastal protection defences to discover the potential influences on vegetation growth from the artificial topography. Impacts of the artificial topography on the sediment element composition were detected by comparing the fixed effects caused by artificial topography and wave exposure using linear mixed models. Surficial sediments under the impacts of artificial topography contain elevated levels of biogenic elements and heavy metals, including C (and organic carbon), N, S, Al, Fe, Mn, Cu, Zn, As, Cd, Cr, Ni, and Pb. The results showed that element enrichment caused by artificial topography reduced the vegetation sexual reproduction. Contrary to the potential inhibition caused by direct wave exposure, which was due to the biomass accumulation limit, the inhibition caused by artificial topography was related to the transition of growth strategy. The contents of Cu, Mn, N, Ni, S and As in the sediments were critical in considering the relationship between the change in the sediment element composition and the alteration in the plant growth. Our study emphasizes the importance of rethinking the impacts of coastal development projects, especially regarding the heterogeneity of sediment element composition and its ecological consequences.

Major and trace elements in Boletus aereus and Clitopilus prunulus growing on volcanic and sedimentary soils of Sicily (Italy).

PubMed

Alaimo, M G; Dongarrà, G; La Rosa, A; Tamburo, E; Vasquez, G; Varrica, D

2018-08-15

The aim of this study was to determine and compare the content of 28 elements (Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Rb, Sb, Se, Sr, Tl, U, V and Zn) in fruiting bodies of Boletus aereus Bull. and Clitopilus prunulus P. Kumm collected from eleven unpolluted sites of Sicily (Italy) and, also to relate the abundance of chemical elements in soil with their concentration in mushrooms. Median concentrations of the most abundant elements in Boletus aereus ranged from 31,290 μg/g (K) to 107 μg/g (Zn) in caps and from 24,009 μg/g (K) to 57 μg/g (Zn) in stalks with the following abundance order: K > Na > Ca > Mg > Fe > Al > Rb > Zn. The same elements, in the whole fruiting body of Clitopilus prunulus samples, varied in the range 54,073-92 μg/g following the abundance order: K > Na > Mg > Ca > Fe > Al > Rb > Zn. Metal contents in Boletus aereus and in the whole fruiting body of Clitopilus prunulus, collected from the same sampling sites, showed statistically significant differences for most elements. In particular, Clitopilus prunulus contained around two to four times more Co, Cr, Fe, Mg, Mo, Pb, U and V than caps and stalks of Boletus aereus species which, in turn, was from two to four times more enriched in Cu, Se and Tl. Thus, the elemental content of Boletus aereus and Clitopilus prunulus appeared to be species-dependent. The distribution of chemical elements in Boletus aereus was not uniform throughout the whole fruiting body as most elements were significantly bioconcentrated in caps. Furthermore, the fruit bodies of Boletus aereus from the volcanic soil differed both in major and minor elements concentrations from those collected from sedimentary soils. Cadmium and lead concentrations were below the threshold limits for wild mushrooms proposed by EU Directives (2008 and 2015). The elemental content was not significantly influenced by soil pH. Copyright © 2018 Elsevier Inc. All rights reserved.

Toxic and essential mineral elements content of black tea leaves and their tea infusions consumed in Iran.

PubMed

Salahinejad, Maryam; Aflaki, Fereydoon

2010-04-01

The metal contents of eleven black tea samples, four cultivated in Iran and seven imported, and their tea infusions were determined. Twelve elements consisting toxic metals (Al, As, Pb, Cr, Cd, and Ni) and essential mineral elements (Fe, Zn, Cu, Mn, Ca, and Mg) were analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Al, Ca, Mg, and Mn ranged in black tea leaves at mg g(-1) levels, while Cr, Fe, Ni, Cu, Zn were at microg g(-1) levels. Analysis of variance showed no statistically significant differences among most elements determined in cultivated and imported black teas in Iran except for Ni and Cu. The extraction efficiency of each element into tea infusions was evaluated. The solubility of measured metals in infusion extracts varied widely and ranged from 0 to 59.3%. Among the studied elements, Cr, Pb, and Cd showed the lowest rates of solubility and Ni had the highest rates of solubility. The amount of toxic metals and essential mineral elements that one may take up through consumption of black tea infusion was estimated. The amount of realizing each element into tea infusions and acceptable daily intake, for safety consumption of black tea, was compared.

LROC Targeted Observations for the Next Generation of Scientific Exploration

NASA Astrophysics Data System (ADS)

Jolliff, B. L.

2015-12-01

Imaging of the Moon at high spatial resolution (0.5 to 2 mpp) by the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Cameras (NAC) plus topographic data derived from LROC NAC and WAC (Wide Angle Camera) and LOLA (Lunar Orbiting Laser Altimeter), coupled with recently obtained hyperspectral NIR and thermal data, permit studies of composition, mineralogy, and geologic context at essentially an outcrop scale. Such studies pave the way for future landed and sample return missions for high science priority targets. Among such targets are (1) the youngest volcanic rocks on the Moon, including mare basalts formed as recently as ~1 Ga, and irregular mare patches (IMPs) that appear to be even younger [1]; (2) volcanic rocks and complexes with compositions more silica-rich than mare basalts [2-4]; (3) differentiated impact-melt deposits [5,6], ancient volcanics, and compositional anomalies within the South Pole-Aitken basin; (4) exposures of recently discovered key crustal rock types in uplifted structures such as essentially pure anorthosite [7] and spinel-rich rocks [8]; and (5) frozen volatile-element-rich deposits in polar areas [9]. Important data sets include feature sequences of paired NAC images obtained under similar illumination conditions, NAC geometric stereo, from which high-resolution DTMs can be made, and photometric sequences useful for assessing composition in areas of mature cover soils. Examples of each of these target types will be discussed in context of potential future missions. References: [1] Braden et al. (2014) Nat. Geo. 7, 787-791. [2] Glotch et al. (2010) Science, 329, 1510-1513. [3] Greenhagen et al. (2010) Science, 329, 1507-1509. [4] Jolliff et al. (2011) Nat. Geo. 4, 566-571. [5] Vaughan et al (2013) PSS 91, 101-106. [6] Hurwitz and Kring (2014) J. Geophys. Res. 119, 1110-1133 [7] Ohtake et al. (2009) Nature, 461, 236-241 [8] Pieters et al. (2014) Am. Min. 99, 1893-1910. [9] Colaprete et al. (2010) Science 330, 463-468.

Mechanical Properties of High Entropy Alloy Al0.1CoCrFeNi for Peripheral Vascular Stent Application.

PubMed

Alagarsamy, Karthik; Fortier, Aleksandra; Komarasamy, Mageshwari; Kumar, Nilesh; Mohammad, Atif; Banerjee, Subhash; Han, Hai-Chao; Mishra, Rajiv S

2016-12-01

High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored. This paper discusses the mechanical behavior and microstructure of Al 0.1 CoCrFeNi HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rates. Results show that Al 0.1 CoCrFeNi alloy possesses characteristics that compare well against currently used stent materials and it can potentially find use in peripheral vascular stent implants and extend their life-cycle.

Microstructure and Properties of the Al-27Si/Cu/Al-50Si Joint Brazed by the Partial Transient Liquid Phase Bonding

NASA Astrophysics Data System (ADS)

Sun, Qingzhu; Wang, Haibo; Yang, Cheng

2018-06-01

Al-27Si and Al-50Si were brazed by using a thin Cu interlayer. The metallurgical bonding without obvious defects is achieved, and a wide brazing seam consisting of fine eutectic structures and coarse Si particles is formed in the Al-27Si/Cu/Al-50Si joint. The deposition of Si element in the liquid phases during solidification results in the formation of the larger Si particles and ultra-small Si particles in the brazing seam. The shear strength of the joint reaches 63 MPa.

Microstructure and Properties of the Al-27Si/Cu/Al-50Si Joint Brazed by the Partial Transient Liquid Phase Bonding

NASA Astrophysics Data System (ADS)

Sun, Qingzhu; Wang, Haibo; Yang, Cheng

2018-04-01

Al-27Si and Al-50Si were brazed by using a thin Cu interlayer. The metallurgical bonding without obvious defects is achieved, and a wide brazing seam consisting of fine eutectic structures and coarse Si particles is formed in the Al-27Si/Cu/Al-50Si joint. The deposition of Si element in the liquid phases during solidification results in the formation of the larger Si particles and ultra-small Si particles in the brazing seam. The shear strength of the joint reaches 63 MPa.

Application of Relational Contracting Methods to Federal Construction Projects

DTIC Science & Technology

2011-03-24

59 viii List of Figures Page Figure 1 Wittgenstein Model (Chan et al., 2010...a precise and comprehensive definition of the concept (Chan et al, 2010). Ludwig Wittgenstein argued that complex concepts are unable to be defined...recently, Chan et al. (2010) utilized the Wittgenstein concept and both of these previous researchers’ work to develop a model of the elements of

Oxidation and corrosion behavior of modified-composition, low-chromium 304 stainless steel alloys

NASA Technical Reports Server (NTRS)

Stephens, J. R.; Barrett, C. A.

1977-01-01

The effects of substituting less strategic elements than Cr on the oxidation and corrosion resistance of AISI 304 stainless steel were investigated. Cyclic oxidation resistance was evaluated at 870 C. Corrosion resistance was determined by exposure of specimens to a boiling copper-rich solution of copper sulfate and sulfuric acid. Alloy substitutes for Cr included Al, Mn, Mo, Si, Ti, V, Y, and misch metal. A level of about 12% Cr was the minimum amount of Cr required for adequate oxidation and corrosion resistance in the modified composition 304 stainless steels. This represents a Cr saving of at least 33%. Two alloys containing 12% Cr and 2% Al plus 2% Mo and 12% Cr plus 2.65% Si were identified as most promising for more detailed evaluation.

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

DOE PAGES

Hlova, Ihor; Goldston, Jennifer F.; Gupta, Shalabh; ...

2017-05-30

Solid-state mechanochemical synthesis of alane (AlH 3) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction,more » which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.« less

A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hlova, Ihor; Goldston, Jennifer F.; Gupta, Shalabh

Solid-state mechanochemical synthesis of alane (AlH 3) starting from sodium hydride (NaH) and aluminum chloride (AlCl 3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl 3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl 3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH 3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction,more » which revealed that the overall reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl 3 system presents some subtle differences compared to LiH–AlCl 3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.« less

Primitive Melt Inclusions from Multiple Samples from the FAMOUS Zone: Insights into the Mantle Melting Column and the Fractionation Processes

NASA Astrophysics Data System (ADS)

Laubier, M.; Langmuir, C. H.

2008-12-01

On mid-ocean ridges, the influential work by Sobolev and Shimizu (Nature, 1993) and Sobolev (Petrology, 1996) has inferred fractional melting during polybaric upwelling by showing that olivine-hosted inclusions were formed over a range of pressures. However melt inclusion studies have often concerned single MORB samples and may be seen as anecdotal in the sense that they are neither repeated nor globally verified. Recent modeling and experimental results also suggest the importance of post-entrapment processes for major and trace elements. This study presents major and trace element data in 300 olivine-hosted melt inclusions from 11 samples from the FAMOUS segment on the Mid-Atlantic Ridge. Published data from Shimizu (Phys. Earth Planet. Int., 1998) and Kamenetsky (EPSL, 1996; spinel-hosted inclusions) are also reported. In parallel, major and trace element measurements were performed in 150 glasses of the segment in order to have consistent datasets. Melt inclusions, trapped in olivine phenocrysts Mg#85-92, display complex trends in major element plots and can be divided into three groups. Group 1, the largest, is characterized by high MgO (9.4-13.4 wt.%), intermediate SiO2 and Al2O3 contents. Group 2 displays distinctively high Al2O3 (up to 18.4 wt.%), low SiO2 (as low as 46.5 wt.%) and high MgO (10.5-12.8 wt.%) contents, along with low CaO and variable TiO2, K2O and incompatible element concentrations. Group 3 consists of the melt inclusions trapped in less primitive olivines (Mg#<88.5) and displays higher SiO2, CaO and trace element contents. In the lava population, two groups can be distinguished. A small subset, that shares many features with the group 2 melt inclusions, displays high MgO and Al2O3 and low SiO2 and incompatible element contents. This type of lava - high-Al, low-Si and high-Mg - has been previously reported for various mid-ocean ridges (e.g., le Roux et al., Contrib. Min. Petrol., 2002; Eason and Sinton, EPSL, 2008). The second group plots along liquid lines of descent at low pressure starting from the compositions of the group 1 melt inclusions. Modeling of continuous polybaric melting and crystallization shows that the different inclusion groups are derived from melts formed at various pressures in the melting column (~12-6 kbar). After segregation from the mantle, the three batches of melts are fractionated at distinct pressures. The group 2 melt inclusions are consistent with the highest pressure of melt formation and a major role of cpx+olivine fractionation at high pressure (8 kbar), whereas group 3 results indicate the lowest pressure of extraction and entrapment (1kbar). An important observation is that high-Al, low-Si lavas contain melt inclusions from both the low-Si, high-Al group 2 and normal compositions (groups 1 and 3). These lavas can be reproduced by mixing between these two populations of inclusions, followed by some extent of differentiation. Therefore, this study shows that lavas represent averages of melts differentiated from the melt inclusions, and that the major element variability among inclusions can be explained by the combined effects of polybaric melting and crystallization at variable pressure. Trace element compositions of group 1 and 2 melt inclusions show large variations; incompatible element ratios (Ba/La, Rb/Nb, etc) suggest local source heterogeneity. Further modeling will be carried out in order to distinguish between the effects of partial melting and source composition.

Plasma-Arc Deposited Elemental Boron Film for use as a Durable Nonstick Coating

DTIC Science & Technology

2007-09-01

therefore inexpensive) to deposit by either magnetron sputtering or vacuum arc techniques. As it turned out, a Ti-coated sample of 1100Al was available...in dual -use applications, such as the ones just mentioned. 2. RESULTS OF THE PHASE I WORK The Phase I project demonstrated that it is possible to...this upgrade, we replaced the original source assembly by one that could handle very long-pulse operation, by including water-cooling in the anode

The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares

NASA Astrophysics Data System (ADS)

Doschek, George A.; Warren, Harry

2016-05-01

Recently Doschek et al. (2015, ApJL, 808, L7) reported on an observation of an enhancement of the abundance of Ar XIV relative to Ca XIV of about a factor of 30 near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. This enhancement yields an argon/calcium abundance ratio 7 times greater than expected from the photospheric abundances. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as due to an inverse First Ionization Potential (FIP) effect. Argon is a high-FIP element and calcium is a low-FIP element. In the published work two lines of Ar XIV were observed and one line was tentatively identified as an Ar XI line. The number of argon lines was limited by the limitations of the flare study that was executed. In this paper we report observing a similar enhancement in a full-CCD EIS flare spectrum in argon lines with reasonable statistics and lack of blending that lie within the EIS wavelength ranges. The observed lines include two Ar XI lines, four Ar XIII lines, six Ar XIV lines, and one Ar XV line. The enhancement is far less than reported in Doschek et al. (2015) but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and is only marginally an inverse FIP effect. However, as for the published cases, this newly discovered enhancement occurs in association with a sunspot in a small area only a few arcsec in size and therefore we feel it is produced by the same physics that produced the strong inverse FIP case. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. (2015) indicate that the argon/calcium enhancement is due to a depletion of low-FIP elements. This work is supported by a NASA Hinode grant.

On-road emission factors of PM pollutants for light-duty vehicles (LDVs) based on urban street driving conditions

NASA Astrophysics Data System (ADS)

Kam, Winnie; Liacos, James W.; Schauer, James J.; Delfino, Ralph J.; Sioutas, Constantinos

2012-12-01

An on-road sampling campaign was conducted on two major surface streets (Wilshire and Sunset Boulevards) in Los Angeles, CA, to characterize PM components including metals, trace elements, and organic species for three PM size fractions (PM10-2.5, PM2.5-0.25, and PM0.25). Fuel-based emission factors (mass of pollutant per kg of fuel) were calculated to assess the emissions profile of a light-duty vehicle (LDV) traffic fleet characterized by stop-and-go driving conditions that are reflective of urban street driving. Emission factors for metals and trace elements were highest in PM10-2.5 while emission factors for PAHs and hopanes and steranes were highest in PM0.25. PM2.5 emission factors were also compared to previous freeway, roadway tunnel, and dynamometer studies based on an LDV fleet to determine how various environments and driving conditions may influence concentrations of PM components. The on-road sampling methodology deployed in the current study captured substantially higher levels of metals and trace elements associated with vehicular abrasion (Fe, Ca, Cu, and Ba) and crustal origins (Mg and Al) than previous LDV studies. The semi-volatile nature of PAHs resulted in higher levels of PAHs in the particulate phase for LDV tunnel studies (Phuleria et al., 2006) and lower levels of PAHs in the particulate phase for freeway studies (Ning et al., 2008). With the exception of a few high molecular weight PAHs, the current study's emission factors were in between the LDV tunnel and LDV freeway studies. In contrast, hopane and sterane emission factors were generally comparable between the current study, the LDV tunnel, and LDV freeway, as expected given the greater atmospheric stability of these organic compounds. Overall, the emission factors from the dynamometer studies for metals, trace elements, and organic species are lower than the current study. Lastly, n-alkanes (C19-C40) were quantified and alkane carbon preference indices (CPIs) were determined to be in the range of 1-2, indicating substantial anthropogenic source contribution for surface streets in Los Angeles.

Phase relations in the system Fe-Si determined in an internally-resistive heated DAC

NASA Astrophysics Data System (ADS)

Komabayashi, T.; Antonangeli, D.; Morard, G.; Sinmyo, R.; Mezouar, N.

2015-12-01

It is believed that the iron-rich Earth's core contains some amounts of light elements on the basis of the density deficit of 7 % compared to pure iron. The identification of the kinds and amounts of the light elements in the core places constraints on the origin, formation, and evolution of the Earth because dissolution of light elements into an iron-rich core should place important constraints on the thermodynamic conditions (pressure (P), temperature (T), and oxygen fugacity) of the equilibration between liquid silicate and liquid iron during the core formation. Among potential light elements, silicon has been attracting attentions because it is abundant in the mantle, partitioned into both solid and liquid irons, and very sensitive to the oxygen fugacity. An important phase relation in iron alloy is a transition between the face-centred cubic (FCC) structure and hexagonal close-packed (HCP) structure. This boundary is a key to infer the stable structure in the inner core and is used to derive thermodynamic properties of the phases (Komabayashi, 2014). In the Fe-Si system, previous reports were based on experiments in laser-heated diamond anvil cells (DAC), which might have included large termperature uncertainties. We have revisited this boundary in the system Fe-Si using an internally resistive-heated DAC combined with synchrotron X-ray diffraction at the beamline ID27, ESRF. The internally-heated DAC (Komabayashi et al., 2009; 2012) provides much more stable heating than the laser-heated DAC and much higher temperature than externally resistive-heated DAC, which enables us to place tight constraints on the P-T locations of the boundaries. Also because the minimum measurable temperature is as low as 1000 K due to the stable electric heating, the internal heating is able to examine the low temperature phase stability which was not studied by the previous studies. We will report the P-T locations of the boundaries and evaluate the effect of Si on the phase relation of Earth's core materials. References Komabayashi, J. Geophys. Res., 119, 2014; Komabayashi et al., Earth Planet. Sci. Lett. 282, 2009; Komabayashi et al., Phys. Chem. Mineral 39, 2012.

Impacts of sampling design and estimation methods on nutrient leaching of intensively monitored forest plots in the Netherlands.

PubMed

de Vries, W; Wieggers, H J J; Brus, D J

2010-08-05

Element fluxes through forest ecosystems are generally based on measurements of concentrations in soil solution at regular time intervals at plot locations sampled in a regular grid. Here we present spatially averaged annual element leaching fluxes in three Dutch forest monitoring plots using a new sampling strategy in which both sampling locations and sampling times are selected by probability sampling. Locations were selected by stratified random sampling with compact geographical blocks of equal surface area as strata. In each sampling round, six composite soil solution samples were collected, consisting of five aliquots, one per stratum. The plot-mean concentration was estimated by linear regression, so that the bias due to one or more strata being not represented in the composite samples is eliminated. The sampling times were selected in such a way that the cumulative precipitation surplus of the time interval between two consecutive sampling times was constant, using an estimated precipitation surplus averaged over the past 30 years. The spatially averaged annual leaching flux was estimated by using the modeled daily water flux as an ancillary variable. An important advantage of the new method is that the uncertainty in the estimated annual leaching fluxes due to spatial and temporal variation and resulting sampling errors can be quantified. Results of this new method were compared with the reference approach in which daily leaching fluxes were calculated by multiplying daily interpolated element concentrations with daily water fluxes and then aggregated to a year. Results show that the annual fluxes calculated with the reference method for the period 2003-2005, including all plots, elements and depths, lies only in 53% of the cases within the range of the average +/-2 times the standard error of the new method. Despite the differences in results, both methods indicate comparable N retention and strong Al mobilization in all plots, with Al leaching being nearly equal to the leaching of SO(4) and NO(3) with fluxes expressed in mol(c) ha(-1) yr(-1). This illustrates that Al release, which is the clearest signal of soil acidification, is mainly due to the external input of SO(4) and NO(3).

In vitro cytotoxicity evaluation of elemental ions released from different prosthodontic materials.

PubMed

Elshahawy, Waleed M; Watanabe, Ikuya; Kramer, Phillip

2009-12-01

This study investigated the cytotoxicity of elemental ions contained in four fixed prosthodontic materials (gold, nickel-chromium, stainless-steel alloys and CAD-CAM ceramics). According to the determination of elements released from prosthodontic materials by using inductively coupled plasma mass spectroscopy, similar amounts of elements Pd, Ag, Zn, Cu, Ni, Cr, Mo, Be, Fe, Al, and K were prepared as salt solutions. Wells with a tenfold higher concentration of the tested elements were used as positive controls, while a well without any tested element was used as a negative control. These salt solutions were tested for cytotoxicity by culturing mouse L-929 fibroblasts in the salt solutions for a 7-day period of incubation. Then, the percentage of viable cells for each element was measured using trypan blue exclusion assay. The data (n=5) were statistically analyzed by ANOVA/Tukey test (p<0.05). The results showed a statistically significant difference for the cytotoxic effect of the tested elements salt solutions. For the released element concentrations the lowest percentage of viable cells (mean+/-SD) was evident with Zn, Cu or Ni indicating that they are the highly toxic elements. Be and Ag were found to be intermediate in cytotoxic effect. Fe, Cr, Mo, Al, Pd or K were found to be the least cytotoxic elements. Zn and Cu released from gold alloys, and Ni released from nickel-chromium alloys, which are commonly used as fixed prosthodontic restorations, show evidence of a high cytotoxic effect on fibroblast cell cultures.

Rocket-Plume Spectroscopy Simulation for Hydrocarbon-Fueled Rocket Engines

NASA Technical Reports Server (NTRS)

Tejwani, Gopal D.

2010-01-01

The UV-Vis spectroscopic system for plume diagnostics monitors rocket engine health by using several analytical tools developed at Stennis Space Center (SSC), including the rocket plume spectroscopy simulation code (RPSSC), to identify and quantify the alloys from the metallic elements observed in engine plumes. Because the hydrocarbon-fueled rocket engine is likely to contain C2, CO, CH, CN, and NO in addition to OH and H2O, the relevant electronic bands of these molecules in the spectral range of 300 to 850 nm in the RPSSC have been included. SSC incorporated several enhancements and modifications to the original line-by-line spectral simulation computer program implemented for plume spectral data analysis and quantification in 1994. These changes made the program applicable to the Space Shuttle Main Engine (SSME) and the Diagnostic Testbed Facility Thruster (DTFT) exhaust plume spectral data. Modifications included updating the molecular and spectral parameters for OH, adding spectral parameter input files optimized for the 10 elements of interest in the spectral range from 320 to 430 nm and linking the output to graphing and analysis packages. Additionally, the ability to handle the non-uniform wavelength interval at which the spectral computations are made was added. This allowed a precise superposition of wavelengths at which the spectral measurements have been made with the wavelengths at which the spectral computations are done by using the line-by-line (LBL) code. To account for hydrocarbon combustion products in the plume, which might interfere with detection and quantification of metallic elements in the spectral region of 300 to 850 nm, the spectroscopic code has been enhanced to include the carbon-based combustion species of C2, CO, and CH. In addition, CN and NO have spectral bands in 300 to 850 nm and, while these molecules are not direct products of hydrocarbon-oxygen combustion systems, they can show up if nitrogen or a nitrogen compound is present as an impurity in the propellants and/or these can form in the boundary layer as a result of interaction of the hot plume with the atmosphere during the ground testing of engines. Ten additional electronic band systems of these five molecules have been included into the code. A comprehensive literature search was conducted to obtain the most accurate values for the molecular and the spectral parameters, including Franck-Cordon factors and electronic transition moments for all ten band systems. For each elemental transition in the RPSSC, six spectral parameters - Doppler broadened line width at half-height, pressure-broadened line width at half-height, electronic multiplicity of the upper state, electronic term energy of the upper state, Einstein transition probability coefficient, and the atomic line center - are required. Input files have been created for ten elements of Ni, Fe, Cr, Co, Cu, Ca, Mn, Al, Ag, and Pd, which retain only relatively moderate to strong transitions in 300 to 430 nm spectral range for each element. The number of transitions in the input files is 68 for Ni; 148 for Fe; 6 for Cr; 87 for Co; 1 for Ca; 3 for Mn; 2 each for Cu, Al, and Ag; and 11 for Pd.

Partially etched Ti3AlC2 as a promising high capacity Lithium-ion battery anode.

PubMed

Chen, Xifan; Zhu, Yuanzhi; Zhu, Xiaoquan; Peng, Wenchao; Li, Yang; Zhang, Guoliang; Zhang, Fengbao; Fan, Xiaobin

2018-06-25

MXenes, a family of two-dimensional transition-metal carbide and nitride materials, are supposed to be the promising materials in energy storage because of the high electronic conductivity, hydrophilic surfaces and low diffusion barriers. MXenes are generally prepared by removing the "A" elements (A = Al, Si, Sn, etc.) from their corresponding MAX phases by using hydrofluoric acid (HF) and the other etching agents, despite the fact that these "A" elements usually have great volumetric and gravimetric capacities. Herein, we studied the etching progress of Ti3AlC2 and evaluated their anode performance in Lithium-ion batteries. We found that a partially etched sample (0.5h-peTi3C2Tx) showed much higher capacity (160 mA h g-1, 331.6 mA h cm-3 at 1C) when compared with the fully etched Ti3C2Tx (110 mA h g-1, 190.3 mA h cm-3 at 1C). Besides, a 99% capacity retention was observed even after 1000 cycles in the 0.5h-peTi3C2Tx anode. This interesting result can be explained, at least in part, by the alloying of the residue Al element during lithiation. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Responses of trace elements to aerobic maximal exercise in elite sportsmen.

PubMed

Otag, Aynur; Hazar, Muhsin; Otag, Ilhan; Gürkan, Alper Cenk; Okan, Ilyas

2014-02-21

Trace elements are chemical elements needed in minute quantities for the proper growth, development, and physiology of the organism. In biochemistry, a trace element is also referred to as a micronutrient. Trace elements, such as nickel, cadmium, aluminum, silver, chromium, molybdenum, germanium, tin, titanium, tungsten, scandium, are found naturally in the environment and human exposure derives from a variety of sources, including air, drinking water and food. The Purpose of this study was investigated the effect of aerobic maximal intensity endurance exercise on serum trace elements as well-trained individuals of 28 wrestlers (age (year) 19.64±1.13, weight (Kg) 70.07 ± 15.69, height (cm) 176.97 ± 6.69) during and after a 2000 meter Ergometer test protocol was used to perform aerobic (75 %) maximal endurance exercise. Trace element serum levels were analyzed from blood samples taken before, immediately after and one hour after the exercise. While an increase was detected in Chromium (Cr), Nickel (Ni), Molybdenum (Mo) and Titanium (Ti) serum levels immediately after the exercise, a decrease was detected in Aluminum (Al), Scandium (Sc) and Tungsten (W) serum levels. Except for aluminum, the trace elements we worked on showed statistically meaningful responses (P < 0.05 and P < 0.001). According to the responses of trace elements to the exercise showed us the selection and application of the convenient sport is important not only in terms of sportsman performance but also in terms of future healthy life plans and clinically.

Refinements to the Graves and Pitarka (2010) Broadband Ground Motion Simulation Method

USGS Publications Warehouse

Graves, Robert; Arben Pitarka,

2015-01-01

This brief article describes refinements to the Graves and Pitarka (2010) broadband ground motion simulation methodology (GP2010 hereafter) that have been implemented in version 14.3 of the SCEC Broadband Platform (BBP). The updated version of our method on the current SCEC BBP is referred to as GP14.3. Our simulation technique is a hybrid approach that combines low-­‐frequency and high-­‐frequency motions computed with different methods into a single broadband response. The separate low-­‐ and high-­‐frequency components have traditionally been called “deterministic” and “stochastic”, respectively; however, this nomenclature is an oversimplification. In reality, the low-­‐frequency approach includes many stochastic elements, and likewise, the high-­‐frequency approach includes many deterministic elements (e.g., Pulido and Kubo, 2004; Hartzell et al., 2005; Liu et al., 2006; Frankel, 2009; Graves and Pitarka, 2010; Mai et al., 2010). While the traditional terminology will likely remain in use by the broader modeling community, in this paper we will refer to these using the generic terminology “low-­‐frequency” and “high-­‐ frequency” approaches. Furthermore, one of the primary goals in refining our methodology is to provide a smoother and more consistent transition between the low-­‐ and high-­‐ frequency calculations, with the ultimate objective being the development of a single unified modeling approach that can be applied over a broad frequency band. GP2010 was validated by modeling recorded strong motions from four California earthquakes. While the method performed well overall, several issues were identified including the tendency to over-­‐predict the level of longer period (2-­‐5 sec) motions and the effects of rupture directivity. The refinements incorporated in GP14.3 are aimed at addressing these issues with application to the simulation of earthquakes in Western US (WUS). These refinements include the addition of a deep weak zone (details in following section) to the rupture characterization and allowing perturbations in the correlation of rise time and rupture speed with the specified slip distribution. Additionally, we have extended the parameterization of GP14.3 so that it is also applicable for simulating Eastern North America (ENA) earthquakes. This work has been guided by the comprehensive set of validation studies described in Goulet and Abrahamson (2014) and Dreger et al. (2014). The GP14.3 method shows improved performance relative to GP2010, and we direct the interested reader to Dreger et al. (2014) for a detailed assessment of the current methodology. In this paper, we concentrate on describing the modifications in more detail, and also discussing additional refinements that are currently being developed.

Magnetism and Solid Solution Effects in NiAI (40% AI) Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chain T; Fu, Chong Long; Chisholm, Matthew F

2007-01-01

The solid solution effects of ternary additions of transition elements in intermetallic Ni-40% Al were investigated by both experimental studies and theoretical calculations. Co solute atoms when sitting at Ni sublattice sites do not affect the lattice parameter and hardening behavior of Ni-40Al. On the other hand, Fe, Mn, and Cr solutes, which are mainly on Al sublattice sites, substantially expand the lattice parameter and produce an unusual solid solution softening effect. First-principles calculations predict that these solute atoms with large unfilled d-band electrons develop large magnetic moments and effectively expand the lattice parameter when occupying Al sublattice sites. Themore » theoretical predictions were verified by both electron loss-energy spectroscopy (EELS) analyses and magnetic susceptibility measurements. The observed softening behavior can be explained quantitatively by the replacement of Ni anti-site defects (potent hardeners) by Fe, Mn, and Cr anti-site defects with smaller atom size mismatch between solute and Al atoms. This study has led to the identification of magnetic interaction as an important physical parameter affecting the solid solution hardening in intermetallic alloys containing transition elements.« less

Investigation of the effect of alumina and compaction pressure on physical, electrical and tribological properties of Al-Fe-Cr-Al2O3 powder composites

NASA Astrophysics Data System (ADS)

Mohsin, Mohammad; Mohd, Aas; Suhaib, M.; Arif, Sajjad; Arif Siddiqui, M.

2017-10-01

In this experimental work, aluminium Al-20Fe-5Cr (in wt.%) matrix reinforced with varying wt.% Al2O3 (0, 10, 20 and 30) and compaction pressure (470, 550 and 600 MPa) were prepared by powder metallurgy technique. The characterization of composites were performed by scanning electron microscopy (SEM), x-ray diffraction (XRD), energy dispersive spectrum (EDS) and elemental mapping. Uniform distribution of Al2O3 in aluminium matrix were observed by elemental mapping. The composites showed an increase in density and hardness by increasing both alumina and compaction pressure. While, electrical conductivity decreased by the addition of alumina. The tribological study of the composites were performed on pin-on-disc apparatus at sliding conditions (applied load 40 N, sliding speed 1.5 m s-1, sliding distance 300 m). The tribological properties of the composites were improved by increasing alumina and compaction pressure. SEM analysis were also carried out to understand wear mechanism of the worn surfaces of various fabricated composites and aluminium matrix.

Effects of Ti and La Additions on the Microstructures and Mechanical Properties of B-Refined and Sr-Modified Al-11Si Alloys

NASA Astrophysics Data System (ADS)

Li, Chenlin; Pan, Ye; Lu, Tao; Jing, Lijun; Pi, Jinhong

2018-03-01

The effects of Ti and La additions on the microstructures and mechanical properties of B-refined and Sr-modified Al-11Si alloys were investigated in the present work. The interactions among Ti, La, B and Sr elements were discussed employing microstructure observation, thermal analysis and tensile test, respectively. It was found that the addition of 0.05 wt% B induces a transformation of eutectic Si from finely fibrous to coarsely plate-like morphology in the Al-11Si alloy with 0.02 wt%Sr modification, owing to the poisoning of IIT mechanism, and the eutectic Si grows only with TPRE mechanism. Both titanium and lanthanum can neutralize the co-poisoning effect between Sr and B in the Al-11Si alloy, but the neutralizing effect of La is dependent on the addition sequence. The combinative addition of La and B elements promotes the effective refinement of α-Al grains, but an inhomogeneous modification of eutectic Si phases is also observed, leading to a slightly decrease in the elongation.

Residual stresses in shape memory alloy fiber reinforced aluminium matrix composite

NASA Astrophysics Data System (ADS)

Tsz Loong, Tang; Jamian, Saifulnizan; Ismail, Al Emran; Nur, Nik Hisyammudin Muhd; Watanabe, Yoshimi

2017-01-01

Process-induced residual stress in shape memory alloy (SMA) fiber reinforced aluminum (Al) matrix composite was simulated by ANSYS APDL. The manufacturing process of the composite named as NiTi/Al is start with loading and unloading process of nickel titanium (NiTi) wire as SMA to generate a residual plastic strain. Then, this plastic deformed NiTi wire would be embedded into Al to become a composite. Lastly, the composite is heated form 289 K to 363 K and then cooled back to 300 K. Residual stress is generated in composite because of shape memory effect of NiTi and mismatch of thermal coefficient between NiTi wire and Al matrix of composite. ANSYS APDL has been used to simulate the distribution of residual stress and strain in this process. A sensitivity test has been done to determine the optimum number of nodes and elements used. Hence, the number of nodes and elements used are 15680 and 13680, respectively. Furthermore, the distribution of residual stress and strain of nickel fiber reinforced aluminium matrix composite (Ni/Al) and titanium fiber reinforced aluminium matrix composite (Ti/Al) under same simulation process also has been simulated by ANSYS APDL as comparison to NiTi/Al. The simulation results show that compressive residual stress is generated on Al matrix of Ni/Al, Ti/Al and NiTi/Al during heating and cooling process. Besides that, they also have similar trend of residual stress distribution but difference in term of value. For Ni/Al and Ti/Al, they are 0.4% difference on their maximum compressive residual stress at 363K. At same circumstance, NiTi/Al has higher residual stress value which is about 425% higher than Ni/Al and Ti/Al composite. This implies that shape memory effect of NiTi fiber reinforced in composite able to generated higher compressive residual stress in Al matrix, hence able to enhance tensile property of the composite.

Trace elements have limited utility for studying migratory connectivity in shorebirds that winter in Argentina

USGS Publications Warehouse

Torres-Dowdall, J.; Farmer, A.H.; Abril, M.; Bucher, E.H.; Ridley, I.

2010-01-01

Trace-element analysis has been suggested as a tool for the study of migratory connectivity because (1) trace-element abundance varies spatially in the environment, (2) trace elements are assimilated into animals' tissues through the diet, and (3) current technology permits the analysis of multiple trace elements in a small tissue sample, allowing the simultaneous exploration of several elements. We explored the potential of trace elements (B, Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, Mn, Ni, Cu, Zn, As, Sr, Cs, Hg, Tl, Pb, Bi, Th, and U) to clarify the migratory connectivity of shorebirds that breed in North America and winter in southern South America. We collected 66 recently replaced secondary feathers from Red Knots (Calidris canutus) at three sites in Patagonia and 76 from White-rumped Sandpipers (C. fuscicollis) at nine sites across Argentina. There were significant differences in trace-element abundance in shorebird feathers grown at different nonbreeding sites, and annual variability within a site was small compared to variability among sites. Across Argentina, there was no large-scale gradient in trace elements. The lack of such a gradient restricts the application of this technique to questions concerning the origin of shorebirds to a small number of discrete sites. Furthermore, our results including three additional species, the Pectoral Sandpiper (C. melanotos), Wilson's Phalarope (Phalaropus tricolor), and Collared Plover (Charadrius collaris), suggest that trace-element profiles change as feathers age. Temporal instability of trace-element values could undermine their application to the study of migratory connectivity in shorebirds. ?? The Cooper Ornithological Society 2010.

Water contamination with heavy metals and trace elements from Kilembe copper mine and tailing sites in Western Uganda; implications for domestic water quality.

PubMed

Abraham, Mwesigye R; Susan, Tumwebaze B

2017-02-01

The mining and processing of copper in Kilembe, Western Uganda, from 1956 to 1982 left over 15 Mt of cupriferous and cobaltiferous pyrite dumped within a mountain river valley, in addition to mine water which is pumped to the land surface. This study was conducted to assess the sources and concentrations of heavy metals and trace elements in Kilembe mine catchment water. Multi-element analysis of trace elements from point sources and sinks was conducted which included mine tailings, mine water, mine leachate, Nyamwamba River water, public water sources and domestic water samples using ICP-MS. The study found that mean concentrations (mg kg -1 ) of Co (112), Cu (3320), Ni (131), As (8.6) in mine tailings were significantly higher than world average crust and were being eroded and discharged into water bodies within the catchment. Underground mine water and leachate contained higher mean concentrations (μg L -1 ) of Cu (9470), Co (3430) and Ni (590) compared with background concentrations (μg L -1 ) in un contaminated water of 1.9, 0.21 and 0.67 for Cu, Co and Ni respectively. Over 25% of household water samples exceeded UK drinking water thresholds for Al of 200 μg L -1 , Co exceeded Winsconsin (USA drinking) water thresholds of 40 μg L -1 in 40% of samples while Fe in 42% of samples exceeded UK thresholds of 200 μg L -1 . The study however found that besides mining activities, natural processes of geological weathering also contributed to Al, Fe, and Mn water contamination in a number of public water sources. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comment on the treatment of residual water content in “A consistent set of parametric models for the two-phase flow of immiscible fluids in the subsurface” by L. Luckner et al.

USGS Publications Warehouse

Nimmo, John R.

1991-01-01

Luckner et al. [1989] (hereinafter LVN) present a clear summary and generalization of popular formulations used for convenient representation of porous media fluid flow characteristics, including water content (θ) related to suction (h) and hydraulic conductivity (K) related to θ or h. One essential but problematic element in the LVN models is the concept of residual water content (θr; in LVN, θw,r). Most studies using θr determine its value as a fitted parameter and make the assumption that liquid flow processes are negligible at θ values less than θr. While the LVN paper contributes a valuable discussion of the nature of θr, it leaves several problems unresolved, including fundamental difficulties in associating a definite physical condition with θr, practical inadequacies of the models at low θ values, and difficulties in designating a main wetting curve.

Thermodynamic tabulations for selected phases in the system CaO-Al2O3-SiO2-H2 at 101.325 kPa (1 atm) between 273.15 and 1800 K

USGS Publications Warehouse

Haas, John L.; Robinson, Glipin R.; Hemingway, Bruch S.

1981-01-01

The standard thermodynamic properties of phases in the lime‐alumina‐silica‐ water system between 273.15 and 1800 K at 101.325 kPa (1 atm) were evalated from published experimental data. Phases included in the compilation are boehmite, diaspore, gibbsite, kaolinite, dickite, halloysite, andalusite, kyanite, sillimanite, Ca‐Al cliniopyroxene, anorthite, gehlenite, grossular, prehnite, zoisite, margarite, wollastonite, cyclowollastonite ( = pseudowollastonite), larnite, Ca olivine, hatrurite, and rankinite. The properties include heat capacity, entropy, relative enthalpy, and the Gibbs energy function of the phases and the enthalpies, Gibbs energies, and equilibrium constants for formation both from the elements and the oxides. Tabulated values are given at 50 K intervals with the 2‐sigma confidence limit at 250 K intervals. Summaries for each phase give the temperature‐ dependent functions for heat capacity, entropy, and relative enthalpy and the experimental data used in the final evaluation.

Metal-doped graphene layers composed with boron nitride-graphene as an insulator: a nano-capacitor.

PubMed

Monajjemi, Majid

2014-11-01

A model of a nanoscale dielectric capacitor composed of a few dopants has been investigated in this study. This capacitor includes metallic graphene layers which are separated by an insulating medium containing a few h-BN layers. It has been observed that the elements from group IIIA of the periodic table are more suitable as dopants for hetero-structures of the {metallic graphene/hBN/metallic graphene} capacitors compared to those from groups IA or IIA. In this study, we have specifically focused on the dielectric properties of different graphene/h-BN/graphene including their hetero-structure counterparts, i.e., Boron-graphene/h-BN/Boron-graphene, Al-graphene/h-BN/Al-graphene, Mg-graphene/h-BN/Mg-graphene, and Be-graphene/h-BN/Be-graphene stacks for monolayer form of dielectrics. Moreover, we studied the multi dielectric properties of different (h-BN)n/graphene hetero-structures of Boron-graphene/(h-BN)n/Boron-graphene.

Line strengths of QED-sensitive forbidden transitions in B-, Al-, F- and Cl-like ions

NASA Astrophysics Data System (ADS)

Bilal, M.; Volotka, A. V.; Beerwerth, R.; Fritzsche, S.

2018-05-01

The magnetic dipole (M 1 ) line strength between the fine-structure levels of the ground configurations in B-, F-, Al-, and Cl-like ions are calculated for the four elements argon, iron, molybdenum, and tungsten. Systematically enlarged multiconfiguration Dirac-Hartree-Fock (MCDHF) wave functions are employed to account for the interelectronic interaction with the Breit interaction included in first-order perturbation theory. The QED corrections are evaluated to all orders in α Z utilizing an effective potential approach. The calculated line strengths are compared with the results of other theories. The M 1 transition rates are reported using accurate energies from the literature. Moreover, the lifetimes in the range of millisecond to picosecond are predicted including the contributions from the transition rate due to the E 2 transition channel. The discrepancies of the predicted rates from those available from the literature are discussed and a benchmark data set of theoretical lifetimes is provided to support future experiments.

Fabrication and Magnetic Properties of Co₂MnAl Heusler Alloys by Mechanical Alloying.

PubMed

Lee, Chung-Hyo

2018-02-01

We have applied mechanical alloying (MA) to produce nanocrystalline Co2MnAl Heusler alloys using a mixture of elemental Co50Mn25Al25 powders. An optimal milling and heat treatment conditions to obtain a Co2MnAl Heusler phase with fine microstructure were investigated by X-ray diffraction, differential scanning calorimeter and vibrating sample magnetometer measurements. α-(Co, Mn, Al) FCC phases coupled with amorphous phase are obtained after 3 hours of MA without any evidence for the formation of Co2MnAl alloys. On the other hand, a Co2MnAl Heusler alloys can be obtained by the heat treatment of all MA samples up to 650 °C. X-ray diffraction result shows that the average grain size of Co2MnAl Heusler alloys prepared by MA for 5 h and heat treatment is in the range of 95 nm. The saturation magnetization of MA powders decreases with MA time due to the magnetic dilution by alloying with nonmagnetic Mn and Al elements. The magnetic hardening due to the reduction of the grain size with ball milling is also observed. However, the saturation magnetization of MA powders after heat treatment increases with MA time and reaches to a maximum value of 105 emu/g after 5 h of MA. It can be also seen that the coercivity of 5 h MA sample annealed at 650 °C is fairly low value of 25 Oe.

First-principles investigation on the structures, energies, electronic and defective properties of Ti2AlN surfaces

NASA Astrophysics Data System (ADS)

Liu, Pei; Han, Xiuli; Sun, Dongli; Wang, Qing

2018-03-01

In this research work, the structures, energies, electronic and defective properties of (0001), (10 1 bar 0) , (11 2 bar 0) and (10 1 bar 3) surfaces of Ti2AlN were investigated systematically by the first-principles calculations based on density functional theory. The (0001) and (10 1 bar 0) are polar surfaces and have different kinds of surface terminations, while the (11 2 bar 0) and (10 1 bar 3) are non-polar surfaces. The calculated results show that the Ti(Al)-, Al- terminated (0001) surfaces experience the least relaxation, and N- terminated (0001) surface experiences the greatest relaxation. The calculated surface energies of non-polar surfaces are independent on the constituent element chemical potential, while surface energies of polar surfaces are correlated with the constituent element chemical potential. It is found that the (0001)-Ti(Al), (0001)-Al, (10 1 bar 0) -TiAl and (10 1 bar 3) surface are stable under the condition of Ti- and Al- rich environments, the (0001)-N surface is the most stable one under the Ti- and Al- poor condition. The electronic structures of all the surfaces except (10 1 bar 3) are significantly influenced by structure relaxations. Furthermore, the monovacancy formation energies on the surface layer are lower than that in the bulk, the monovacancies are most difficult to exist on the (10 1 bar 3) surface among all the surfaces.

Mechanisms and FEM Simulation of Chip Formation in Orthogonal Cutting In-Situ TiB2/7050Al MMC

PubMed Central

Wang, Wenhu; Jiang, Ruisong; Lin, Kunyang; Shao, Mingwei

2018-01-01

The in-situ TiB2/7050Al composite is a new kind of Al-based metal matrix composite (MMC) with super properties, such as low density, improved strength, and wear resistance. This paper, for a deep insight into its cutting performance, involves a study of the chip formation process and finite element simulation during orthogonal cutting in-situ TiB2/7050Al MMC. With chips, material properties, cutting forces, and tool geometry parameters, the Johnson–Cook (J–C) constitutive equation of in-situ TiB2/7050Al composite was established. Then, the cutting simulation model was established by applying the Abaqus–Explicit method, and the serrated chip, shear plane, strain rate, and temperature were analyzed. The experimental and simulation results showed that the obtained material’s constitutive equation was of high reliability, and the saw-tooth chips occurred commonly under either low or high cutting speed and small or large feed rate. From result analysis, it was found that the mechanisms of chip formation included plastic deformation, adiabatic shear, shearing slip, and crack extension. In addition, it was found that the existence of small, hard particles reduced the ductility of the MMC and resulted in segmental chips. PMID:29662047

Senator Doug Jones (D-AL) Tour of MSFC Facilities

NASA Image and Video Library

2018-02-22

Senator Doug Jones (D-AL.) and wife, Louise, tour Marshall Space Flight facilities. Steve Doering, manager, Stages Element, Space Launch System (SLS) program at MSFC, along with Senator and Mrs. Jones, viewed the MSFC campus from the top of test stand 4693.

Microstructure engineering of Pt-Al alloy thin films through Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Harris, R. A.; Terblans, J. J.; Swart, H. C.

2014-06-01

A kinetic algorithm, based on the regular solution model, was used in conjunction with the Monte Carlo method to simulate the evolution of a micro-scaled thin film system during exposure to a high temperature environment. Pt-Al thin films were prepared via electron beam physical vapor deposition (EB-PVD) with an atomic concentration ratio of Pt63:Al37. These films were heat treated at an annealing temperature of 400 °C for 16 and 49 minutes. Scanning Auger Microscopy (SAM) (PHI 700) was used to obtain elemental maps while sputtering through the thin films. Simulations were run for the same annealing temperatures and thin-film composition. From these simulations theoretical depth profiles and simulated microstructures were obtained. These were compared to the experimentally measured depth profiles and elemental maps.

A New Discrete Element Sea-Ice Model for Earth System Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, Adrian Keith

Sea ice forms a frozen crust of sea water oating in high-latitude oceans. It is a critical component of the Earth system because its formation helps to drive the global thermohaline circulation, and its seasonal waxing and waning in the high north and Southern Ocean signi cantly affects planetary albedo. Usually 4{6% of Earth's marine surface is covered by sea ice at any one time, which limits the exchange of heat, momentum, and mass between the atmosphere and ocean in the polar realms. Snow accumulates on sea ice and inhibits its vertical growth, increases its albedo, and contributes to pooledmore » water in melt ponds that darken the Arctic ice surface in the spring. Ice extent and volume are subject to strong seasonal, inter-annual and hemispheric variations, and climatic trends, which Earth System Models (ESMs) are challenged to simulate accurately (Stroeve et al., 2012; Stocker et al., 2013). This is because there are strong coupled feedbacks across the atmosphere-ice-ocean boundary layers, including the ice-albedo feedback, whereby a reduced ice cover leads to increased upper ocean heating, further enhancing sea-ice melt and reducing incident solar radiation re ected back into the atmosphere (Perovich et al., 2008). A reduction in perennial Arctic sea-ice during the satellite era has been implicated in mid-latitude weather changes, including over North America (Overland et al., 2015). Meanwhile, most ESMs have been unable to simulate observed inter-annual variability and trends in Antarctic sea-ice extent during the same period (Gagne et al., 2014).« less

Three-dimensional nanometer scale analyses of precipitate structures and local compositions in titanium aluminide engineering alloys

NASA Astrophysics Data System (ADS)

Gerstl, Stephan S. A.

Titanium aluminide (TiAl) alloys are among the fastest developing class of materials for use in high temperature structural applications. Their low density and high strength make them excellent candidates for both engine and airframe applications. Creep properties of TiAl alloys, however, have been a limiting factor in applying the material to a larger commercial market. In this research, nanometer scale compositional and structural analyses of several TiAl alloys, ranging from model Ti-Al-C ternary alloys to putative commercial alloys with 10 components are investigated utilizing three dimensional atom probe (3DAP) and transmission electron microscopies. Nanometer sized borides, silicides, and carbide precipitates are involved in strengthening TiAl alloys, however, chemical partitioning measurements reveal oxygen concentrations up to 14 at. % within the precipitate phases, resulting in the realization of oxycarbide formation contributing to the precipitation strengthening of TiAl alloys. The local compositions of lamellar microstructures and a variety of precipitates in the TiAl system, including boride, silicide, binary carbides, and intermetallic carbides are investigated. Chemical partitioning of the microalloying elements between the alpha2/gamma lamellar phases, and the precipitate/gamma-matrix phases are determined. Both W and Hf have been shown to exhibit a near interfacial excess of 0.26 and 0.35 atoms nm-2 respectively within ca. 7 nm of lamellar interfaces in a complex TiAl alloy. In the case of needle-shaped perovskite Ti3AlC carbide precipitates, periodic domain boundaries are observed 5.3+/-0.8 nm apart along their growth axis parallel to the TiAl[001] crystallographic direction with concomitant composition variations after 24 hrs. at 800°C.

High-order space-time finite element schemes for acoustic and viscodynamic wave equations with temporal decoupling.

PubMed

Banks, H T; Birch, Malcolm J; Brewin, Mark P; Greenwald, Stephen E; Hu, Shuhua; Kenz, Zackary R; Kruse, Carola; Maischak, Matthias; Shaw, Simon; Whiteman, John R

2014-04-13

We revisit a method originally introduced by Werder et al. (in Comput. Methods Appl. Mech. Engrg., 190:6685-6708, 2001) for temporally discontinuous Galerkin FEMs applied to a parabolic partial differential equation. In that approach, block systems arise because of the coupling of the spatial systems through inner products of the temporal basis functions. If the spatial finite element space is of dimension D and polynomials of degree r are used in time, the block system has dimension ( r + 1) D and is usually regarded as being too large when r > 1. Werder et al. found that the space-time coupling matrices are diagonalizable over [Formula: see text] for r ⩽ 100, and this means that the time-coupled computations within a time step can actually be decoupled. By using either continuous Galerkin or spectral element methods in space, we apply this DG-in-time methodology, for the first time, to second-order wave equations including elastodynamics with and without Kelvin-Voigt and Maxwell-Zener viscoelasticity. An example set of numerical results is given to demonstrate the favourable effect on error and computational work of the moderately high-order (up to degree 7) temporal and spatio-temporal approximations, and we also touch on an application of this method to an ambitious problem related to the diagnosis of coronary artery disease. Copyright © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.

High-order space-time finite element schemes for acoustic and viscodynamic wave equations with temporal decoupling

PubMed Central

Banks, H T; Birch, Malcolm J; Brewin, Mark P; Greenwald, Stephen E; Hu, Shuhua; Kenz, Zackary R; Kruse, Carola; Maischak, Matthias; Shaw, Simon; Whiteman, John R

2014-01-01

We revisit a method originally introduced by Werder et al. (in Comput. Methods Appl. Mech. Engrg., 190:6685–6708, 2001) for temporally discontinuous Galerkin FEMs applied to a parabolic partial differential equation. In that approach, block systems arise because of the coupling of the spatial systems through inner products of the temporal basis functions. If the spatial finite element space is of dimension D and polynomials of degree r are used in time, the block system has dimension (r + 1)D and is usually regarded as being too large when r > 1. Werder et al. found that the space-time coupling matrices are diagonalizable over for r ⩽100, and this means that the time-coupled computations within a time step can actually be decoupled. By using either continuous Galerkin or spectral element methods in space, we apply this DG-in-time methodology, for the first time, to second-order wave equations including elastodynamics with and without Kelvin–Voigt and Maxwell–Zener viscoelasticity. An example set of numerical results is given to demonstrate the favourable effect on error and computational work of the moderately high-order (up to degree 7) temporal and spatio-temporal approximations, and we also touch on an application of this method to an ambitious problem related to the diagnosis of coronary artery disease. Copyright © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd. PMID:25834284

Elemental concentration variations in Plio-Pleistocene sediments from ODP Site 1143 (southern South China Sea) obtained by XRF analyses

NASA Astrophysics Data System (ADS)

Tian, J.; Xie, X.; Jin, H.; Wang, P.; Jian, Z.

2009-12-01

Energy dispersive X-ray fluorescence (XRF) scanning technology provides the most accurate and most economic analytical methods for the determination of major and minor elements of the deep-sea sediment ranging from sodium (11) to uranium (92). Scanning on the smooth core surface by XRF Core scanner is reliable and non-destructive to the sediment, requiring little or no time to prepare the core. This method overcomes the drawback of the traditional analytical method by ICP-AES or ICP-MS which requires long time for sample preparation. Thus, it makes it viable to reconstruct long and high-resolution elemental time series from sediment cores. We have performed relatively elemental concentration analyses on the deep sea sediment cores from ODP site 1143 (southern SCS) down to 190.77 mcd (meters composite depth) by XRF core scanner. The depth resolution of the scanning is 1 cm, equivalent to a time resolution of ~250 years. The age model is based on tuning the benthic foraminiferal d18O at Site 1143 to obliquity and precession (Tian et al., 2002) which indicates that the 190.77 meters long sediment spans the past 5 Myr. We compared the records between 99.5 and 136.46 mcd with the elemental records from the same site obtained by Philips PW 2400 X-ray spectrometer (Wehausen et al., online publication). Comparison reveals, regardless of the absolute changes of the elements, that the elemental records (Si, Ti, Al, Fe, Mn, Ca, K, P, Ba, Rb, Sr) obtained by two methods are nearly the same. Results show that the relative concentration variations of the productivity related elements such as Ba and Ca display distinctive glacial-interglacial cycles for the past 5 Myr. These productivity cycles recorded show one-on-one relationship with the glacial-interglacial cycles of the global ice volume change recorded in the benthic foraminiferal d18O. The glacial-interglacial cycles in productivity and global ice volume changes are consistent with each other not only in amplitude but also in secular variations. The benthic d18O implies the final formation of the northern hemisphere glaciation between ~2.5 Ma and ~3.3 Ma, as indicated by gradually increased values of d18O. During this period, both Ba and Ca show gradually increased values of relative concentration, indicating increased productivity which was probably caused by intensified East Asia summer monsoon. The close relationship of the productivity related elemental variations with benthic foraminiferal d18O reveals that the Plio-Pleistocene variations of the East Asian monsoon have been greatly dominated by global ice volume change. Although the elements related to terrigenous detrital matter composition of site 1143 such as Ti, Fe, As, Co and Ni display distinct glacial-interglacial cycles for the past 5 Myr, they display different patterns in secular variation with that of the benthic foraminiferal d18O. The mismatch indicates that besides northern hemisphere glaciation other multiple processes including changes in provenance and weathering intensity caused by monsoonal climate variability and sea level fluctuations could have affected the terrigenous detrital matter composition of site 1143.

Elements of effective palliative care models: a rapid review

PubMed Central

2014-01-01

Background Population ageing, changes to the profiles of life-limiting illnesses and evolving societal attitudes prompt a critical evaluation of models of palliative care. We set out to identify evidence-based models of palliative care to inform policy reform in Australia. Method A rapid review of electronic databases and the grey literature was undertaken over an eight week period in April-June 2012. We included policy documents and comparative studies from countries within the Organisation for Economic Co-operation and Development (OECD) published in English since 2001. Meta-analysis was planned where >1 study met criteria; otherwise, synthesis was narrative using methods described by Popay et al. (2006). Results Of 1,959 peer-reviewed articles, 23 reported systematic reviews, 9 additional RCTs and 34 non-randomised comparative studies. Variation in the content of models, contexts in which these were implemented and lack of detailed reporting meant that elements of models constituted a more meaningful unit of analysis than models themselves. Case management was the element most consistently reported in models for which comparative studies provided evidence for effectiveness. Essential attributes of population-based palliative care models identified by policy and addressed by more than one element were communication and coordination between providers (including primary care), skill enhancement, and capacity to respond rapidly to individuals’ changing needs and preferences over time. Conclusion Models of palliative care should integrate specialist expertise with primary and community care services and enable transitions across settings, including residential aged care. The increasing complexity of care needs, services, interventions and contextual drivers warrants future research aimed at elucidating the interactions between different components and the roles played by patient, provider and health system factors. The findings of this review are limited by its rapid methodology and focus on model elements relevant to Australia’s health system. PMID:24670065

Children's, parents' and other stakeholders' perspectives on early dietary self-management to delay disease progression of chronic disease in children: a protocol for a mixed studies systematic review with a narrative synthesis.

PubMed

Pugh, Pearl; Hemingway, Pippa; Christian, Martin; Higginbottom, Gina

2018-01-25

Chronic disease of childhood may be delayed by early dietary intervention. The purpose of this systematic review is to provide decision-makers with a perspective on the role of early dietary intervention, as a form of self-management, to delay disease progression in children with early chronic disease, as described by children, parents and other stakeholders. The study will systematically review empirical research (qualitative, quantitative and mixed method designs), including grey literature, using a narrative synthesis. A four-stage search process will be conducted involving a scoping search, the Scottish Intercollegiate Guidelines Network (SIGN) Patient Issues search filter on MEDLINE, the search of seven databases using a chronic disease and chronic kidney disease (CKD) search strategy, and hand searching the reference lists of identified papers for additional studies. All studies retrieved during the search process will undergo a screening and selection process against the inclusion/exclusion criteria. Methodological quality of relevant studies will be assessed using a validated Mixed Studies Review scoring system, before inclusion in the review. Relevant grey literature will be assessed for methodological quality and relative importance using McGrath et al.'s framework and the Academy Health advisory committee categories, respectively. Data extraction will be guided by the Centre for Review and Dissemination guidance and Popay et al.'s work. The narrative synthesis of the findings will use elements of Popay et al.'s methodology of narrative synthesis, applying recognised tools for each of the four elements: (1) developing a theory of how the intervention works, why and for whom; (2) developing a preliminary synthesis of findings of included studies; (3) exploring relationships in the data; and (4) assessing the robustness of the synthesis. This mixed studies systematic review with a narrative synthesis seeks to elucidate the gaps in current knowledge and generate a fresh explanation of research findings on early dietary self-management in chronic disease, with particular application to CKD, from the stakeholders' perspective. The review will provide an important platform to inform future research, identifying the facilitators and barriers to implementing early dietary interventions. Ultimately, the review will contribute vital information to inform future improvements in chronic disease. The lead author has a particular interest in CKD paediatric service delivery. The review has been registered with PROSPERO (CRD42017078130).