Observation of the magnetic C 4 phase in Ca 1 - x Na x Fe 2 As 2 and its universality in the hole-doped 122 superconductors

DOE PAGES

Taddei, K. M.; Allred, J. M.; Bugaris, D. E.; ...

2017-02-15

Since its discovery in 2014, the magnetic tetragonal C 4 phase has been identified in a growing number of hole-doped 122 Fe-based superconducting compounds. Exhibiting a unique double-Q magnetic structure and a strong competition with both superconducting and magnetic order parameters, the C 4 phase and the conditions of its formation are of significant interest to understanding the fundamental mechanisms in these materials. Particularly, separating the importance of direct changes to the relative size of hole and electron pockets at the Fermi surface (achieved via charge doping) from the role of structural changes due to differences of ionic radii ofmore » dopants is useful to determine the underlying parameter which causes the C 4 instability. Here, we report the discovery of the C 4 phase in a fourth member of the hole-doped 122 materials Ca 1-xNa xFe 2As 2(0.20 ≤ x ≤ 0.50) as determined from neutron and x-ray powder diffraction studies. The maximum of the C 4 dome is observed at x = 0.44 with a reentrant temperature T r = 52 K and an extent of Δx ~ 0.07 in composition. It is observed that for a range of compositions within the C 4 dome (0.40 ≤ x ≤ 0.42), there is a second reentrance (Tr 2 < Tr) where the antiferromagnetic C 2 phase is recovered—a feature previously only seen in Ba 1-xK xFe 2As 2. A phase diagram is presented for Ca 1-xNa xFe 2As 2 and compared to the other Na-doped 122's—A 1-xNa xFe 2As 2 with A = Ba, Sr, and Ca. Lastly, the structural parameters for these three systems are compared and the importance of the “chemical pressure” due to changing the A-site ion (A = Ba, Sr, Ca) is discussed.« less

[Analysis of mineral elements in different organs at different harvesting times of Schizonepeta tenuifolia on ICP-AES].

PubMed

Shan, Ming-Qiu; Yu, Sheng; Yu, Li-Xia; Ding, An-Wei

2014-02-01

To study the main storage organ of each mineral element in Schizonepeta tenuifolia, and explain its reasonable harvesting time and medicinal parts in view of mineral elements. The mineral elements of Schizonepeta tenuifolia in different organs at different harvesting times were determined by ICP-AES technique. The mineral elements, K, Ca, Na, P, Mg, Mn, Zn, Cu, Fe, Mo, were determined in the study. The results showed that at different harvesting times, (1) the contents of K, P, Cu in fringe and the contents of Mg, Ca, Na, Fe, Mn, Zn in leaf were highest among different organs. (2) among the macroelements, the contents of K and Ca were highest while the content of Na was lowest; among the microelements, the content of Fe was highest while the content of Mo was lowest. (3) in item, the proportion of K:P was highest while the proportion of Zn: Cu was lowest; in fringe, the proportions of Ca:Mg and Fe:Mn were lowest. (4) within the harvest period, variations of the mineral elements were not obvious. In the stem of Schizonepeta tenuifolia, the contents of every mineral elements were lower than other organs, including leaves and spikes. Considering the mineral elements, the correlations of harvesting time and content change were not remarkable.

Optimization of Performance of Arc Welding Using Fluxes in Welded Ship Structures from HY-100 and HY-130 KPSI.

DTIC Science & Technology

1981-09-01

production and formulation for several decades. NMgO + NCaO + NMnO + NFeO + NAI 20 3Basicity = NSiO 2 + NTi0 2 + NZr0 2 + NA1 203 This differs from the widely...20 3 100 (CaO-SiO, )(40) slag CaO/SiO 2 0.15 none 2600 NCaO /NSiO2 0.17 8% FeSi 1900 16% FeSi 1700 32% FeSi 1400 52 I Table 8 (continued). Islag Ca0...SiO~e .79 none 1200 NCaO /NSiOz .84 2% FeSi 1000 4% FeSi 900 16% FeSi 500 32% FeSi 500 Mechanical Property Tests Mechanical property weldments were

[Characterization and optimization of the NaOH-EDTA extracts for solution 31P-NMR analysis of organic phosphorus in river sediments].

PubMed

Zhang, Wen-Qiang; Shan, Bao-Qing; Zhang, Hong; Tang, Wen-Zhong

2014-01-01

Optimization and mechanism of NaOH-EDTA extraction solutions were studied in phosphorus (P) pollution river sediments, which were Fe, Al-rich sediment, by solution 31P nuclear magnetic resonance spectroscopy (31P-NMR). Different proportions of NaOH and EDTA showed different extraction efficiency on total P (TP) and organic P (Po) in the sediment. The concentration of Po in NaOH + EDTA extract was higher than that in NaOH extract. The mechanism was that the TP and Po were released under the conditions of EDTA chelating with Fe and Al. The concentration of TP and Po were the highest in 1.00 mol x L(-1) NaOH +75 mmol x L(-1) EDTA extract and 0.25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA extract, which were 3.88 mg x g(-1) and 0.24 mg x g(-1), respectively. The extractions of Fe, Mn, Ca, Mg, Al were increasing as the EDTA increased under the same NaOH concentration. Extraction efficiency of Fe, Mn, Ca showed negative correlation with the pH of the extracting solution (P < 0.01). Exponential relationship was found between the extraction of Al and the pH of the extraction solution (P < 0.01) because of the AlO2- and EDTA-Al complex. The quality of spectra of NaOH-EDTA extract was better than that of NaOH extract. Six P species were detected in different extractions, including phosphonates, orthophosphate, pyrophosphate, orthophosphate monoesters, phospholipids and deoxyribonucleic acids. Therefore, 0. 25 mol x L(-1) NaOH + 50 mmol x L(-1) EDTA was the optimization extraction solution for Po analysis in Fe and Al-rich river sediment by 31P-NMR.

Abundances in the red giants of M13 and M22

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

Lehnert, M.D.; Bell, R.A.; Cohen, J.G.

Abundances of Ca, Na, and Fe are derived for 10 red giant branch stars in the globular clusters M13 and M22, by means of model atmosphere analyses of high-dispersion spectra. It was found that M13 and M22 represent two different types of globular clusters. M13 is similar to M92 and many other globular clusters in that it displays variations in CH and CN band strengths, while showing no variation in either Ca or Fe abundance. The Na abundance was found to vary and its variation correlates with CN band strengths. This suggests that the source of the observed CN bandmore » strength variation is the same as that of the Na variation. M22, on the other hand, is similar to Omega Cen, in that it displays variations in Ca, Na, and Fe abundances, and these variations correlate with variations in CH and CN band strengths. These correlations suggest that the cause of the variations in M22 is largely primordial, and that mixing may only make a relatively small contribution to the C and N variations observed. 61 refs.« less

Sensory Acceptability of Iron-Fortified Red Lentil (Lens culinaris Medik.) Dal.

PubMed

Podder, Rajib; Khan, Shaan M; Tar'an, Bunyamin; Tyler, Robert T; Henry, Carol J; Jalal, Chowdhury; Shand, Phyllis J; Vandenberg, Albert

2018-03-01

Panelists in Saskatoon, Canada (n = 45) and Dhaka, Bangladesh (n = 98) participated in sensory evaluations of the sensory properties of both cooked and uncooked dehulled red lentil dal fortified with FeSO 4 ·7H 2 O, NaFeEDTA or FeSO 4 ·H 2 O at fortificant Fe concentrations of 800, 1,600 (both cooked and uncooked), or 2,800 ppm. Appearance, odor, and overall acceptability of cooked and uncooked samples were rated using a 9-point hedonic scale (1 = dislike extremely to 9 = like extremely). Taste and texture were rated for the cooked samples prepared as typical south Asian lentil meals. Significant differences in sensory quality were observed among all uncooked and cooked samples at both locations. Overall, scores for all sensory attributes and acceptability of uncooked lentil decreased with increasing concentration of Fe in the fortificant; however, Fe fortification (particularly with NaFeEDTA) had small effects on acceptability. Panelists from Saskatoon provided a wider range of scores than those from Bangladesh for all attributes of cooked lentil. Overall, sensory evaluation of Fe fortification using NaFeEDTA minimally affected consumer perception of color, taste, texture, odor, and overall acceptability of cooked lentil. Reliability estimates (Cronbach's alpha [CA]) indicated that consumer scores were generally consistent for all attributes of all lentil samples (mean CA > 0.80). NaFeEDTA was found to be the most suitable Fe fortificant for lentil based on consumer acceptability. Consumption of 45 to 50 g of NaFeEDTA-fortified lentil (fortificant Fe concentration of 1,600 ppm) per day meets the estimated average requirements (EARs) of Fe for humans (10.8 to 29.4 mg). Iron fortification of dehulled lentil dal may change organoleptic attributes that can influence consumer acceptability. Sensory evaluation by consumers helps to determine the effect on appearance, odor, taste, texture, and overall acceptability of fortified lentils. In this study, consumer acceptability was evaluated with panelists who consume lentil regularly. Panelists provided significantly different scores for 5 sensory attributes for 10 uncooked and 3 cooked lentil samples. Panelists reliably preferred NaFeEDTA as the most suitable Fe fortificant for dehulled lentils for 5 attributes. Overall, lentil dal fortified with NaFeEDTA can offer a simple and low-cost solution to human health problems associated with iron-related malnutrition. © 2018 Institute of Food Technologists®.

ICP-AES Determination of Mineral Content in Boletus tomentipes Collected from Different Sites of China.

PubMed

Wang, Xue-mei; Zhang, Ji; Li, Tao; Li, Jie-qing; Wang, Yuan-zhong; Liu, Hong-gao

2015-05-01

P, Na, Ca, Cu, Fe, Mg, Zn, As, Cd, Co, Cr and Ni, contents have been examined in caps and stipes of Boletus tomentipes collected from different sites of Yunnan province, southwest China. The elements were determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES) with microwave digestion. P, Ca, Mg, Fe, Zn and Cu were the most abundant amongst elements determined in Boletus tomentipes. The caps were richer in P, Mg, Zn and Cd, and the stipes in Ca, Co and Ni. Cluster analysis showed a difference between Puer (BT7 and BT8) and other places. The PCA explained about 77% of the total variance, and the minerals differentiating these places were P (PC1) together with Ca, Cu, Fe, Mg, As and Ni, Na (PC2) together with Cd, and Zn (PC3). The results of this study imply that element concentrations of a mushroom are mutative when collected from the different bedrock soil geochemistry.

Origin of coronas in metagabbros of the Adirondack mts., N. Y

USGS Publications Warehouse

Whitney, P.R.; McLelland, J.M.

1973-01-01

Metagabbros from two widely separated areas in the Adirondacks show development of coronas. In the Southern Adirondacks, these are cored by olivine which is enclosed in a shell of orthopyroxene that is partially, or completely, rimmed by symplectites consisting of clinopyroxene and spinel. Compositions of the corona phases have been determined by electron probe and are consistent with a mechanism involving three partial reactions, thus: (a) Olivine=Orthopyroxene+(Mg, Fe)++. (b) Plagioclase+(Mg, Fe)+++Ca++=Clinopyroxene+Spinel+Na+. (c) Plagioclase+(Mg, Fe)+++Na+=Spinel+more sodic plagioclase+Ca++. Reaction (a) occurs in the inner shell of the corona adjacent to olivine; reaction (b) in the outer shell; and (c) in the surrounding plagioclase, giving rise to the spinel clouding which is characteristic of the plagioclase in these rocks. Alumina and silica remain relatively immobile. These reactions, when balanced, can be generalized to account for the aluminous nature of the pyroxenes and for changing plagioclase composition. Summed together, the partial reactions are equivalent to: (d) Olivine + Anorthite = Aluminous orthopyroxene + Aluminous Clinopyroxene + Spinel (Kushiro and Yoder, 1966). In the Adirondack Highlands, coronas between olivine and plagioclase commonly have an outer shell of garnet replacing the clinopyroxene/spinel shell. The origin of the garnet can also be explained in terms of three partial reactions: (e) Orthopyroxene+Ca++=Clinopyroxene+(Mg, Fe)++. (f) Clinopyroxene+Spinel+Plagioclase+(Mg, Fe)++=Garnet+Ca+++Na+. (g) Plagioclase+(Mg, Fe)+++Na+=Spinel + more sodic plagioclase+Ca++. These occur in the inner and outer corona shell and the surrounding plagioclase, respectively, and involve the products of reactions (a)-(d). Alumina and silica are again relatively immobile. Balanced, and generalized to account for aluminous pyroxenes and variable An content of plagioclase, they are equivalent to: (h) Orthopyroxene+Anorthite+Spinel=Garnet (Green and Ringwood, 1967). Amphibole coronas about opaque oxides in rocks of both areas are the result of oxide/plagioclase reactions with addition of magnesium from coexisting olivine. Based on published experimental data, pressure and temperature at the time of corona formation were on the order of 8 kb and 800?? C for the garnet bearing coronas, with somewhat lower pressures indicated for the clinopyroxene/spinel coronas. ?? 1973 Springer-Verlag.

Evidence from an Ice Core of a Large Impact Circa 1443 A.D.

NASA Astrophysics Data System (ADS)

Abbott, D.; Biscaye, P.; Cole-Dai, J.; Breger, D.

2005-12-01

Published data on melt water from the Siple Dome ice core show distinct anomalies at 1443.16 A.D. The Ca value is 111 ppb, over 9 times the next highest Ca value between 850-1760 A.D. The K value is 20 ppb, about 1.4 times the next highest K value. The Ca anomaly may be due to partial dissolution of CaCO3 microfossils from the 24 km Mahuika bolide impact crater on the southern New Zealand shelf. Deep-sea samples of the Mahuika ejecta layer contain >98% carbonate microfossils. The Mahuika impact may have produced tsunami runups of 130 meters in Jervis Bay, Australia. The Australian megatsunami deposits date to 1450±50 A.D. We analyzed the melt water from 8 ice-core samples from the West Antarctic Siple Dome ice core that date from 1440-1448 A.D. The 1443 A.D. level contained a peak in K of 53 ppb as compared to a background of ~6-7 ppb. Ca was high at 26 ppb but this is not as pronounced as reported earlier. We extracted solid material from the melt water. Except for the 1443 A.D. horizon and one fractured grain at the 1442 A.D. level, most samples were barren except for typical dust. At the 1443 A.D. level, we found 5 carbonate microfossils (coccoliths?) from 5 to 20 microns across. Two were round and solid. One microfossil appeared either caught during mitosis or broken during deformation and elongation. Another carbonate microfossil was unbroken, but appeared deformed into a square. We found a Cu grain with a small amount of oxygen. It is most likely a grain of native copper with an oxidized surface. Deformed microfossils and native minerals are both characteristic of bolide impacts. We also found many microcrystalline magnetite cubes, with an average crystal size of 0.3 microns or less. The high magnetic susceptibility of impact ejacta layers is caused by microcrystalline magnetite. We found a grain of conchoidally fractured feldspar ~15 microns long. A semi-quantitive EDAX analysis found 21% Si, 55% O, 9% Al, 5% Na, 3% K, 2% Fe, and 1% Ca (atomic %), well within the range of K-feldspar compositions. Because Fe does not fit into the feldspar structure, its occurrence implies either that the Fe-bearing feldspar is a glass, or that the Fe is in microcracks within the grain. As ice is not Fe-rich, the former is more likely. Because conchoidal fracture is characteristic of glass, this suggests that the feldspar is a glass (maskelynite) derived from an impact onto continental crust. We also found Al Fe oxide, Ti Al oxide, and amphibole. A semi-quantitative EDAX analysis of the latter found 53% O, 20% Si, 5% Na, 4% Al, Mg, and Fe, 3% Ca, and 0.5% K (atomic %) with trace Ti, S and Cl, close to the composition of the alkali amphibole richterite, which forms in contact metamorphosed limestones (skarns). The Al Fe oxide is most likely hercynite, a spinel that forms in contact metamorphic aureoles in silica-poor environments. All mineral grains had distinct edges. We also found radiating, fibrous crystals of a Ca Na silicate. An EDAX analysis of the mineral found 59% O, 13% Ca, 8% Si, 3% Na, and 1% Mg (atomic %). The Ca Na silicate is most likely pectolite (NaCa2Si3O8), which has radiating, fibrous crystals and forms in skarns. The presence of minerals characteristic of contact metamorphism is important as we have found abundant skarn facies minerals in the Mahuika ejecta layer within deep sea sediment. Thus, our data taken together are most consistent with an impact ejecta layer within the Siple Dome ice core that comes from the Mahuika impact event about 4044 kilometers away; providing a well-constrained date for the event around 1443 A.D.

Content and distribution of macro- and micro-elements in the body of pasture-fed young horses.

PubMed

Grace, N D; Pearce, S G; Firth, E C; Fennessy, P F

1999-03-01

To determine the content and distribution of Na, K, Ca, P, Mg, S, Cu, Mn, Fe and Zn in the body of pasture-fed young horses and then use a factorial model to calculate the dietary mineral requirements for growth. Twenty-one foals were killed at about 150 days of age and the organs, soft tissues, skin and bones and a sample of muscle were dissected out and weighted. The mineral concentrations of elements in all soft tissues and bones were measured by inductively coupled emission spectrometry. The total mineral element composition associated with a tissue was determined from the weight of tissue and its mineral element concentration. Expressed as a percent of total body mineral elements, muscle contained 20% Na, 78% K, 32% Mg, 62% Cu, 36% Mn and 57% Zn, bone contained 47% Na, 99% Ca, 81% P, 62% Mg, 30% Mn and 28% Zn while the organs accounted for a smaller percentage ranging from 0.06% for Ca to 26% for Fe. In liver Cu accounted for 9.2% of total body Cu. Each kilogram of empty body weight was associated with 1.0 g Na, 2.5 g K, 17.1 g Ca, 10.1 g P, 0.4 g Mg, 1.1 mg Cu, 0.39 mg Mn, 52.5 mg Fe and 21.4 mg Zn. The mineral element content of body weight gain is a component used in the factorial model to determine dietary mineral element requirements for growth. The calculated dietary mineral requirements, expressed per kg dry matter, for a 200 kg horse gaining 1.0 kg/day were 1.0 g Na, 2.1 g K, 4.6 g Ca, 3.5 g P, 0.7 g Mg, 4.5 mg Cu and 25 mg Zn.

Iron overload impact on P-ATPases.

PubMed

Sousa, Leilismara; Pessoa, Marco Tulio C; Costa, Tamara G F; Cortes, Vanessa F; Santos, Herica L; Barbosa, Leandro Augusto

2018-03-01

Iron is a chemical element that is active in the fundamental physiological processes for human life, but its burden can be toxic to the body, mainly because of the stimulation of membrane lipid peroxidation. For this reason, the action of iron on many ATPases has been studied, especially on P-ATPases, such as the Na + ,K + -ATPase and the Ca 2+ -ATPase. On the Fe 2+ -ATPase activity, the free iron acts as an activator, decreasing the intracellular Fe 2+ and playing a protection role for the cell. On the Ca 2+ -ATPase activity, the iron overload decreases the enzyme activity, raising the cytoplasmic Ca 2+ and decreasing the sarco/endoplasmic reticulum and the Golgi apparatus Ca 2+ concentrations, which could promote an enzyme oxidation, nitration, and fragmentation. However, the iron overload effect on the Na + ,K + -ATPase may change according to the tissue expressions. On the renal cells, as well as on the brain and the heart, iron promotes an enzyme inactivation, whereas its effect on the erythrocytes seems to be the opposite, directly stimulating the ATPase activity, or stimulating it by signaling pathways involving ROS and PKC. Modulations in the ATPase activity may impair the ionic transportation, which is essential for cell viability maintenance, inducing irreversible damage to the cell homeostasis. Here, we will discuss about the iron overload effect on the P-ATPases, such as the Na + ,K + -ATPase, the Ca 2+ -ATPase, and the Fe 2+ -ATPase.

Characterizing the composition and evolution of and urban particles in Chongqing (China) during summertime

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo; Mi, Tian; Cao, Junji; Shi, Guangming; Huang, Rujin; Wang, Huanbo; Chen, Jun; Lou, Shengrong; Wang, Qiyuan

2017-05-01

Urban particles were investigated using a single particle aerosol mass spectrometer (SPAMS) in Chongqing during the summertime (from 07/05/2014 to 08/06/2014). Chemical composition, mixing state, and atmospheric behavior of urban particles were studied. The major particle types include ECOC (Elemental-Carbon-Organic-Carbon 20.6%), OC (20.1%), KSec (K-Secondary) (13.3%), BB (Biomass burning, 11.9%), NaK (sodium-potassium-rich, 7.3%), Al-rich (4.0%), Fe-rich (3.2%), Ca-rich (1.4%), Ca-EC (1.6%), and NaKPb (0.5%). EC, ECOC, OC, and Ca-EC were prevalent in the condensation mode (< 0.7 μm), while KSec, EC, NaK were significant in both the droplet mode (0.7-1.1 μm) and coarse mode. Increases in aged groups such as EC, KSec, and NaK were observed in the afternoon. Case studies suggested that wet scavenging (rain) rates of different single particle types followed an order of NaKPb > Fe-rich > EC > Ca-EC > Ca-rich > KSec > OC > NaK > ECOC > Al-rich > BB. Increased number fraction of EC and KSec were correlated with the increase of odd oxygen (Ox = O3 + NO2). EC, OC, and ECOC were enriched at higher relative humidity. The findings of this study on the mixing state, temporal variation, processing, and evolution of single particles provide new insight into the atmospheric behavior and impacts of urban particles.

[Analysis of inorganic elements in hydroponic Taraxacum mongolicum grown under different spectrum combinations by ICP-AES].

PubMed

Chen, Xiao-li; Morewane, M B; Xue, Xu-zhang; Guo, Wen-zhong; Wang, Li-chun

2015-02-01

Dandelion (Taraxacum mongolicum) was hydroponically cultured in a completely enclosed plant factory, in which fluorescence and LED emitting spectra of different bands were used as the sole light source for plant growth. Effects of spectral component on the growth of dandelion were studied and the contents of ten inorganic elements such as K, P, Ca, Mg, Na, Fe, Mn, Zn, Cu and B in dandelion were analyzed by ICP-AES technology. The results showed that: (1) Under the condition of similar photosynthetic active radiation (PAR), single R or combined spectrums of FLRB were beneficial for biomass accumulation, while single B was the contrary; (2) Macroelements content ratio in Taraxacum mongolicum grown under FLwas K:Ca:P:Mg : Na=79.74:32.39:24.32:10.55:1.00, microelements content ratio was Fe:Mn:B:Zn:Cu = 9.28:9.71:3.82:2.08:1.00; (3) Red light (peak at 660 nm) could promote the absorptions of Ca, Fe, Mn, Zn, while absorption of Cu was not closely related to spectral conditions; (4) Thehighest accumulation of Ca, Na, Mn and Zn were obtained in aerial parts of Taraxacum mongolicum plants grown under pure red spectrum R, while the accumulation of the rest six elements reached the highest level under the mixed spectrum FLRB.

CaFe interstellar clouds

NASA Astrophysics Data System (ADS)

Bondar, A.; Kozak, M.; Gnaciński, P.; Galazutdinov, G. A.; Beletsky, Y.; Krełowski, J.

2007-07-01

A new kind of interstellar cloud is proposed. These are rare (just a few examples among ~300 lines of sight) objects with the CaI 4227-Å, FeI 3720-Å and 3860-Å lines stronger than those of KI (near 7699 Å) and NaI (near 3302 Å). We propose the name `CaFe' for these clouds. Apparently they occupy different volumes from the well-known interstellar HI clouds where the KI and ultraviolet NaI lines are dominant features. In the CaFe clouds we have not found either detectable molecular features (CH, CN) or diffuse interstellar bands which, as commonly believed, are carried by some complex, organic molecules. We have found the CaFe clouds only along sightlines toward hot, luminous (and thus distant) objects with high rates of mass loss. In principle, the observed gas-phase interstellar abundances reflect the combined effects of the nucleosynthetic history of the material, the depletion of heavy elements into dust grains and the ionization state of these elements which may depend on irradiation by neighbouring stars. Based on data collected using the Maestro spectrograph at the Terskol 2-m telescope, Russia; and on data collected using the ESO Feros spectrograph; and on data obtained from the ESO Science Archive Facility acquired with the UVES spectrograph, Chile. E-mail: `arctur'@rambler.ru (AB); marizak@astri.uni.torun.pl (MK); pg@iftia.univ.gda.pl (PG); gala@boao.re.kr (GAG); ybialets@eso.org (YB); jacek@astri.uni.torun.pl (JK)

Chemistry of impact events on Mercury

NASA Astrophysics Data System (ADS)

Berezhnoy, Alexey A.

2018-01-01

Based on the equilibrium thermochemical approach and quenching theory, formation of molecules and dust grains in impact-produced clouds formed after collisions between meteoroids and Mercury is considered. Based on observations of Al, Fe, and Mn atoms in the exosphere of Mercury and new results of studies of the elemental composition of the surface of Mercury, quenching temperatures and pressures of main chemical reactions and condensation of dust particles were estimated. The behavior of the main Na-, K-, Ca-, Fe-, Al-, Mn-, Mg-, Si-, Ti, Ni-, Cr-, Co, Zn-, O-, H-, S-, C-, Cl-, N-, and P-containing species delivered to the Hermean exosphere during meteoroid impacts was studied. The importance of meteoroid bombardment as a source of Na, K, Ca, Fe, Al, Mn, Mg, and O atoms in the exosphere of Mercury is discussed.

Cytocompatibility, mechanical and dissolution properties of high strength boron and iron oxide phosphate glass fibre reinforced bioresorbable composites.

PubMed

Sharmin, Nusrat; Hasan, Muhammad S; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

2016-06-01

In this study, Polylactic acid (PLA)/phosphate glass fibres (PGF) composites were prepared by compression moulding. Fibres produced from phosphate based glasses P2O5-CaO-MgO-Na2O (P45B0), P2O5-CaO-MgO-Na2O-B2O3 (P45B5), P2O5-CaO-MgO-Na2O-Fe2O3 (P45Fe3) and P2O5-CaO-MgO-Na2O-B2O3-Fe2O3 (P45B5Fe3) were used to reinforce the bioresorbable polymer PLA. Fibre mechanical properties and degradation rate were investigated, along with the mechanical properties, degradation and cytocompatibility of the composites. Retention of the mechanical properties of the composites was evaluated during degradation in PBS at 37°C for four weeks. The fibre volume fraction in the composite varied from 19 to 23%. The flexural strength values (ranging from 131 to 184MPa) and modulus values (ranging from 9.95 to 12.29GPa) obtained for the composites matched those of cortical bone. The highest flexural strength (184MPa) and modulus (12.29GPa) were observed for the P45B5Fe3 composite. After 28 days of immersion in PBS at 37°C, ~35% of the strength profile was maintained for P45B0 and P45B5 composites, while for P45Fe3 and P45B5Fe3 composites ~40% of the initial strength was maintained. However, the overall wet mass change of P45Fe3 and P45B5Fe3 remained significantly lower than that of the P45B0 and P45B5 composites. The pH profile also revealed that the P45B0 and P45B5 composites degraded quicker, correlating well with the degradation profile. From SEM analysis, it could be seen that after 28 days of degradation, the fibres in the fractured surface of P45B5Fe3 composites remain fairly intact as compared to the other formulations. The in vitro cell culture studies using MG63 cell lines revealed both P45Fe3 and P45B5Fe3 composites maintained and showed higher cell viability as compared to the P45B0 and P45B5 composites. This was attributed to the slower degradation rate of the fibres in P45Fe3 and P45B5Fe3 composites as compared with the fibres in P45B0 and P45B5 composites. Copyright © 2015 Elsevier Ltd. All rights reserved.

Abundance ratios in dwarf elliptical galaxies

NASA Astrophysics Data System (ADS)

Şen, Ş.; Peletier, R. F.; Boselli, A.; den Brok, M.; Falcón-Barroso, J.; Hensler, G.; Janz, J.; Laurikainen, E.; Lisker, T.; Mentz, J. J.; Paudel, S.; Salo, H.; Sybilska, A.; Toloba, E.; van de Ven, G.; Vazdekis, A.; Yesilyaprak, C.

2018-04-01

We determine abundance ratios of 37 dwarf ellipticals (dEs) in the nearby Virgo cluster. This sample is representative of the early-type population of galaxies in the absolute magnitude range -19.0 < Mr < -16.0. We analyse their absorption line-strength indices by means of index-index diagrams and scaling relations and use the stellar population models to interpret them. We present ages, metallicities, and abundance ratios obtained from these dEs within an aperture size of Re/8. We calculate [Na/Fe] from NaD, [Ca/Fe] from Ca4227, and [Mg/Fe] from Mgb. We find that [Na/Fe] is underabundant with respect to solar, whereas [Mg/Fe] is around solar. This is exactly opposite to what is found for giant ellipticals, but follows the trend with metallicity found previously for the Fornax dwarf NGC 1396. We discuss possible formation scenarios that can result in such elemental abundance patterns, and we speculate that dEs have disc-like star formation history (SFH) favouring them to originate from late-type dwarfs or small spirals. Na-yields appear to be very metal-dependent, in agreement with studies of giant ellipticals, probably due to the large dependence on the neutron-excess in stars. We conclude that dEs have undergone a considerable amount of chemical evolution, they are therefore not uniformly old, but have extended SFH, similar to many of the Local Group galaxies.

The Universal Cpx Jd-Di barometer for mantle peridotite eclogite and pyroxenites and it using for the mantle petrology

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor

2015-04-01

The Jd-Di exchange in clinopyroxenes used for the calibration of pyroxene barometer (Ashchepkov, 2000;2002; Ashchepkov et al 2010;2011;2012) was transformed to make one universal equation for mantle peridotite eclogites and pyroxenites. The original barometer (Ashchepkov, 2002) calibrated on pressures produced by Opx barometry (McGregor , 1974) was transformed (Ashchepkov et al ., 2004; 2010; 2011) to satisfy the increasing data bases for the mantle xenoliths and experimental values 530 in peridotitic and 650 in elcogitic systems . The obtained difference Pd =Pcpx- Pexp were studied for the dependence on each component and their combination . Instead of the common activities we used the temperature-dependent empirical equations. The three separate equations for the common peridotites, pyroxenites and eclogites (Ashchepkov et al., 2010) were checked and complex To and Al-Na-Fe dependent universal coefficients were received. The KD is determined as follows: KD=Na/AlCr*Mg/Ca The logarithmic dependence between P and KD was transformed to a linear one. Final pressure equations are: AlCr=(Al-0.01) *((T-600)/700)**0.75+Cr*(ToK-100)/1000+(4*Ti-0.0125)/ (T0-801)*650 +0.55*((Fe-0.23) *(T0-900)/10000-K) P=0.26*(5+12*(Al+0.30*Na)KD* ToK**0.75 /(1+Fe+ Fe*(ToK-600)/1000)-ln(1273/ ToK))*40*(7*Na-Al-15*Ti+10*Cr+Mg/4)+7.5*Si-20*( Al*Na*Mg/Ca/(Al-2*Ti+Na-2*Fe/(Fe+Mg))+50*(Na+0.1*Al-2*Ti+0.05*Mg-0.22*Ca-0.7*Na)/Ca). Obtained equation in combination with the (Nimis,Taylor, 2000) thermometer allow to reconstruct position of the magma feeder systems of the alkali basaltic magma withing the mantle diapirs in modern platforms like in Vitim plateau (Ashchepkov et al., 2011) and now was applicated to reconstruct the deep seated magma conduits beneath the mountain collision systems, island arcs ocean plateaus etc. This equation allows to receive the positions of the major groups of eclogites mantle sections and to find out the regularities of their behavior. The Fe rich eclogites commonly trace he boundary between the lower upper part of subcontinental lithospheric mantle (SCLM) at 3 -4 GPa marking pyroxenite eclogites layer. Ca- rich eclogites and especially grospydites in SCLM beneath Precambrian kimberlites occurs near pyroxenite layer but in younger mantle sections they became common in the lower parts marking presence of the subducted sediments. The Mg Cr- less group eclogites commonly diamondiferous and referring to the ancient island arc complexes are also common in the middle part of mantle sections and near 5-6 GPa. The group is often dominated in the young kimberlites and sometimes is highly diamondiferous. Commonly P-Fe# for eclogites in the lower SCLM part show rising Fe# with decreasing pressures which very of then reflect the differentiation of the magmatic systems commonly rather significant. Commonly the Fe#-values for the eclogites show that they can't be simple subucted oceanic basalts but material remelted not only during the low angle "hot"subduction but also under the influence of the kimberlite melts including protokimberlite magmas. The Mg - rich and Fe rich pyroxenites also show the extending in pressures trends which suggest the anatexic melting under the influence of volatiles or under the plum magma hybridization. RBRF grants 05-05-64718, 03-05-64146; 11 -05-00060a; 11-05-91060-PICS. Projects 77-2, 65-03, 02-05 IGM SD RAS and ALROSA Stock Company.

Characterization of Sintering Dust, Blast Furnace Dust and Carbon Steel Electric Arc Furnace Dust

NASA Astrophysics Data System (ADS)

Chang, Feng; Wu, Shengli; Zhang, Fengjie; Lu, Hua; Du, Kaiping

In order to make a complete understanding of steel plant metallurgical dusts and to realize the goal of zero-waste, a study of their properties was undertaken. For these purposes, samples of two sintering dusts (SD), two blast furnace dusts (BFD), and one electric arc furnace dust (EAFD) taken from the regular production process were subjected to a series of tests. The tests were carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy via SEM (EDS), and Fourier transform infrared spectroscopy (FTIR). The dominant elements having an advantage of reuse are Fe, K, Cl, Zn, C. The dominant mineralogical phases identified in sintering dust are KCl, Fe2O3, CaCO3, CaMg(CO3)2, NaCl, SiO2. Mineralogical phases exist in blast furnace dust are Fe2O3, Fe3O4, with small amount of KCl and kaolinite coexist. While in electric arc furnace dust, Fe3O4, ZnFe2O4, CaCO3, CaO, Ca(OH)2 are detected.

Arbuscular mycorrhizas enhance nutrient uptake in different wheat genotypes at high salinity levels under field and greenhouse conditions.

PubMed

Mardukhi, Baran; Rejali, Farhad; Daei, Gudarz; Ardakani, Mohammad Reza; Malakouti, Mohammad Javad; Miransari, Mohammad

2011-07-01

Since most experiments regarding the symbiosis between arbuscular mycorrhizal (AM) fungi and their host plants under salinity stress have been performed only under greenhouse conditions, this research work was also conducted under field conditions. The effects of three AM species including Glomus mosseae, G. etunicatum and G. intraradices on the nutrient uptake of different wheat cultivars (including Roshan, Kavir and Tabasi) under field and greenhouse (including Chamran and Line 9) conditions were determined. At field harvest, the concentrations of N, Ca, Mg, Fe, Cu, and Mn, and at greenhouse harvest, plant growth, root colonization and concentrations of different nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl were determined. The effects of wheat cultivars on the concentrations of N, Ca, and Mn, and of all nutrients were significant at field and greenhouse conditions, respectively. In both experiments, AM fungi significantly enhanced the concentrations of all nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl. The synergistic and enhancing effects of co-inoculation of AM species on plant growth and the inhibiting effect of AM species on Na(+) rather than on Cl(-) uptake under salinity are also among the important findings of this research work. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

High waterborne Mg does not attenuate the toxic effects of Fe, Mn, and Ba on Na+ regulation of Amazonian armored catfish tamoatá (Hoplosternum litoralle).

PubMed

Duarte, Rafael M; Benaduce, Ana Paula; Garcia, Luciano; Gomes, Levy C; Gomes, Adriana Chippari; Val, Adalberto L; Baldisserotto, Bernardo

2018-04-24

Formation water (FoW) is a by-product from oil and gas production and usually has high concentrations of soluble salts and metals. Calcium (Ca) and magnesium (Mg) have been shown to reduce the toxicity of metals to aquatic animals, and previous study showed that high waterborne Ca exerts mild effect against disturbances on Na + regulation in Amazonian armored catfish tamoatá (Hoplosternum littorale) acutely exposed to high Fe, Mn, and Ba levels. Here, we hypothesized that high Mg levels might also reduce the toxic effects of these metals on Na + regulation of tamoatá. The exposure to 5% FoW promoted an increase in Na + uptake and a rapid accumulation of Na + in all tissues analyzed (kidney

Disproportionation of marokite at high pressures and temperatures with geophysical implications

NASA Astrophysics Data System (ADS)

Liu, Lin-gun

1983-07-01

Natural marokite (CaMn 2O 4) has been studied at high pressures and temperatures using a diamond-anvil press coupled with laser heating in the pressure range 100-250 kbar. A mixture of marokite, CaMnO 3 (perovskite) and MnO (rocksalt) has been observed in all runs in the above pressure range by X-ray diffraction study of the quenched samples. It was interpreted that marokite disproportionates into the mixture CaMnO 3 (perovskite) + MnO (rocksalt) at pressures below 100 kbar. A general comparison of the molar volume for all known compounds having the marokite-related structures (including CaFe 2O 4 and CaTi 2O 4) with those for a mixture of perovskite plus rocksalt structures suggested that the mixture is more stable than the marokite-related structures at high pressures, as confirmed by the present experimental result. The CaFe 2O 4-modification of common nepheline (NaAlSiO 4) is also suggested to be unstable relative to the component oxides of α-NaAlO 2 + SiO 2 (stishovite) at high pressures.

AFLOWLIB.ORG: a Distributed Materials Properties Repository from High-throughput Ab initio Calculations

DTIC Science & Technology

2011-11-15

uncle) fcc (uncle) hcp (uncle) phase-diagram Ag Al Al Au Au Bi Bi Ca Ca Cd Cd Ce Ce Co Co Cr Cr Cu Cu Fe Fe Ga Ga Gd Gd Ge Ge Hf...Hf Hg Hg In In Ir Ir La La Li Li Mg Mg Mn Mn Mo Mo Na Na Nb Nb Ni Ni Os Os Pb Pb Pd Pd Pt Pt Rb Rb Re Re Rh Rh Ru Ru Sb Sb Sc...2 S. Curtarolo, A. N. Kolmogorov, and F. H. Cocks, High-throughput ab initio analysis of the Bi-In, Bi- Mg , Bi-Sb, In- Mg , In-Sb, and Mg -Sb systems

[Analysis of mineral elements of sunflower (Helianthus annuus L.) grown on saline land in Hetao Irrigation District by ICP-AES].

PubMed

Tong, Wen-Jie; Chen, Fu; Wen, Xin-Ya

2014-01-01

The absorption and accumulation of ten mineral elements in four kinds of organs (root, steam, leaf and flower disc) in Helianthus annuus L. plants cultured in Hetao Irrigation District under different level of salinity stress were determined by ICP-AES with wet digestion (HNO3 + HClO4). The results showed that: (1) The contents of Fe, Mn, Zn, Ca, and Na were highest in roots, so was K in stems, B and Mg in leaves and P in flower discs, while no significant difference was detected in the content of Cu among these organs; (2) The cumulants of Ca, Mg, P, Cu, B and Zn were highest in flower discs, so were Na, Fe and Mn in roots and K in stems; (3) In sunflower plants, the proportion of mineral element cumulant for K : Ca : Mg : P : Na was 16.71 : 5.23 : 3.86 : 1.23 : 1.00, and for Zn : Fe : B : Mn: Cu was 56.28 : 27.75 : 1.93 : 1.17 : 1.00, respectively; (4) The effect of salinity stress on absorption of mineral elements differed according to the kind of organ and element, root was the most sensitive to soil salt content, followed by stem and leaf, and the effect on flower disc seemed complex.

Magnetic penetration-depth measurements of a suppressed superfluid density of superconducting Ca0.5Na0.5Fe2As2 single crystals by proton irradiation

NASA Astrophysics Data System (ADS)

Kim, Jeehoon; Haberkorn, N.; Graf, M. J.; Usov, I.; Ronning, F.; Civale, L.; Nazaretski, E.; Chen, G. F.; Yu, W.; Thompson, J. D.; Movshovich, R.

2012-10-01

We report on the dramatic effect of random point defects, produced by proton irradiation, on the superfluid density ρs in superconducting Ca0.5Na0.5Fe2As2 single crystals. The magnitude of the suppression is inferred from measurements of the temperature-dependent magnetic penetration depth λ(T) using magnetic force microscopy. Our findings indicate that a radiation dose of 2×1016 cm-2 produced by 3 MeV protons results in a reduction of the superconducting critical temperature Tc by approximately 10%. In contrast, ρs(0) is suppressed by approximately 60%. This breakdown of the Abrikosov-Gorkov theory may be explained by the so-called “Swiss cheese model,” which accounts for the spatial suppression of the order parameter near point defects similar to holes in Swiss cheese. Both the slope of the upper critical field and the penetration depth λ(T/Tc)/λ(0) exhibit similar temperature dependences before and after irradiation. This may be due to a combination of the highly disordered nature of Ca0.5Na0.5Fe2As2 with large intraband and simultaneous interband scattering as well as the s±-wave nature of short coherence length superconductivity.

A Comparative Study on Macro- and Microelement Bioaccumulation Properties of Leaves and Bark of Quercus petraea and Pinus sylvestris.

PubMed

Klink, Agnieszka; Polechońska, Ludmiła; Dambiec, Małgorzata; Białas, Kamila

2018-01-01

Trees are widely used for biomonitoring and filtering air in industrial, urban, and rural areas. This research was undertaken to examine accumulation capacities of macroelements (Ca, K, Mg, Na) and trace metals (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in needles and bark of Pinus sylvestris and leaves and bark of Quercus petraea growing in the vicinity of the chlor-alkali plant PCC Rokita in Brzeg Dolny (Lower Silesia, SW Poland). Because Scots pine is well studied and considered a useful bioindicator, we have used this species as a base for comparison of the accumulation ability of sessile oak that shows some features of good bioindicator, but whose biogeochemistry was scarcely studied. Results showed that for both species leaves contained more macroelements (Ca, K, Mg), whereas the bark was richer in most trace metals (Cd, Cr, Cu, Fe, and Pb). However, trees studied differed with respect to element content. Oak bark and leaves were more effective in accumulating macro- and trace elements (bark Cd, Co, Cr, Cu, K, Mg, Mn, Na, Ni, Pb and leaves Ca, Cr, Cu, Fe, K, Mg, Na, Ni) than Scots pine tissues. Nevertheless, foliar metal accumulation index of these species was similar, suggesting that their overall ability to accumulate trace metals was similar.

The influence of manganese treatment on the distribution of metal elements in rats and the protection by sodium para-amino salicylic acid.

PubMed

Yuan, Zong-Xiang; Chen, Hai-Bin; Li, Shao-Jun; Huang, Xiao-Wei; Mo, Yu-Huan; Luo, Yi-Ni; He, Sheng-Nan; Deng, Xiang-Fa; Lu, Guo-Dong; Jiang, Yue-Ming

2016-07-01

Manganese (Mn) overexposure induced neurological damages, which could be potentially protected by sodium para-aminosalicylic acid (PAS-Na). In this study, we systematically detected the changes of divalent metal elements in most of the organs and analyzed the distribution of the metals in Mn-exposed rats and the protection by PAS-Na. Sprague Dawley (SD) rats received intraperitoneal injections of 15mg/kg MnCl2·4H2O (5d/week for 3 weeks), followed by subcutaneous (back) injections of PAS-Na (100 and 200mg/kg, everyday for 5 weeks). The concentrations of Mn and other metal elements [Iron (Fe), Copper (Cu), Zinc (Zn), Magnesium (Mg), Calcium (Ca)] in major organs (liver, spleen, kidney, thighbone and iliac bone, cerebral cortex, hippocampus and testes) and blood by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results showed that Mn overexposure significantly increased Mn in most organs, Fe and Zn in liver, Fe and Mg in blood; however decreased Fe, Cu, Zn, Mg and Ca in cortex, Cu and Zn in kidney, Cu and Mg in iliac bone, and Zn in blood. In contrast, PAS-Na treatment restored most changes particularly in cortex. In conclusion, excessive Mn exposure disturbed the balance of other metal elements but PAS-Na post-treatments could restore these alterations. Copyright © 2016 Elsevier GmbH. All rights reserved.

Preparation of Ferrotitanium from Ilmenite by Electrolysis-Assisted Calciothermic Reduction in CaCl2-NaCl Molten Salt

NASA Astrophysics Data System (ADS)

Zhou, Zhongren; Hua, Yixin; Xu, Cunying; Li, Jian; Li, Yan; Gong, Kai; Ru, Juanjian; Xiong, Li

2016-02-01

Electrolysis-assisted calciothermic reduction method is proposed and successfully used to prepare ferrotitanium alloy from ilmenite by using equal-molar CaCl2-NaCl molten salt as electrolyte, molybdenum rod as cathode, and graphite as anode at 973 K with cell voltages of 3.2-4.4 V under inert atmosphere. Thermodynamics analysis of the process is presented, and the products obtained are examined with x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. It is demonstrated that the calciothermic reduction of ilmenite is a stepwise process since intermediate CaTiO3 is observed in the products partially reduced. In the calciothermic reduction process, the reduction of FeTiO3 first gives rise to the formation of Fe and CaTiO3, which as intermediates will further react with calcium metal to form ferrotitanium alloys. This is in good agreement with the prediction of thermodynamics. Experimental results also show that increasing cell voltage can accelerate the formation of calcium metal through electrolysis of CaO and CaCl2 and, hence, promote the calciothermic reduction of ilmenite. As the electrolytic zone and reduction zone are combined in the same bath, the theoretical energy requirement for the production of FeTi in the calciothermic process is lower than that in the aluminothermic process.

A preliminary analysis of trace-elemental signatures in statoliths of different spawning cohorts for Dosidicus gigas off EEZ waters of Chile

NASA Astrophysics Data System (ADS)

Liu, Bilin; Chen, Xinjun; Fang, Zhou; Hu, Song; Song, Qian

2015-12-01

We applied solution-based ICP-MS method to quantify the trace-elemental signatures in statoliths of jumbo flying squid, Dosidius gigas, which were collected from the waters off northern and central Chile during the scientific surveys carried out by Chinese squid jigging vessels in 2007 and 2008. The age and spawning date of the squid were back-calculated based on daily increments in statoliths. Eight elemental ratios (Sr/Ca, Ba/Ca, Mg/Ca, Mn/Ca, Na/Ca, Fe/Ca, Cu/Ca and Zn/Ca) were analyzed. It was found that Sr is the second most abundant element next to Ca, followed by Na, Fe, Mg, Zn, Cu, Ba and Mn. There was no significant relationship between element/Ca and sea surface temperature (SST) and sea surface salinity (SSS), although weak negative or positive tendency was found. MANOVA analysis showed that multivariate elemental signatures did not differ among the cohorts spawned in spring, autumn and winter, and no significant difference was found between the northern and central sampling locations. Classification results showed that all individuals of each spawned cohorts were correctly classified. This study demonstrates that the elemental signatures in D. gigas statoliths are potentially a useful tool to improve our understanding of its population structure and habitat environment.

The excretion of biotrace elements using the multitracer technique in tumour-bearing mice.

PubMed

Wang, X; Tian, J; Yin, X M; Zhang, X; Wang, Q Z

2000-12-01

A radioactive multitracer solution obtained from the nuclear reaction of selenium with 25 MeV/nucleon 40Ar ions was used for investigation of trace element excretion into the faeces and urine of cancerous mice. The excretion rates of 22 elements (Na, K, Rb, Mg, Ca, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Mo, Nb, Tc, Ru, Ag and In) were simultaneously measured under strictly identical experimental conditions, in order to clarify the excretion behavior of these elements in cancerous mice. The faecal and urinary excretion rates of Mg, Sr, Ga, As, Sc, V, Cr, Mn, Co, Fe, Y, Zr, Nb, Ru and Mo in cancerous mice, showed the in highest value at 0-8 hours. The accumulative excretion of Ca, Mo, Y and Zr was decreased and Na, Fe, Mn and Co increased in tumour-bearing mice, when compared to normal mice.

The Eclogite-Garnetite transformation in the MORB + H 2O system

NASA Astrophysics Data System (ADS)

Okamoto, Kazuaki; Maruyama, Shigenori

2004-08-01

To decipher phase relations of oceanic crust in the coldest slab at the mantle transition zone, multi-anvil experiments were conducted in the MORB+H 2O system at pressures of 10-19 GPa, and temperatures of 700-1500 °C. Garnet and stishovite were recognized in all run charges. Above 15 GPa, garnet drastically increases NaSi (Na 2MSi 5O 12) component (M = Ca, Mg, Fe 2+), jadeite occurs instead of omphacite. Na-, K-hollandite containing 7 mol% NaAlSi 3O 8 and Ca-perovskite with 60 mol% CaTiO 3, were observed at P>17 GPa. With decomposition of omphacite and increase of modal ratio of garnet, there is a sharp increase of density at 440 km. The density increase due to appearance of Ca-perovskite at 570 km, is estimated approximately 100 km shallower than that of previous estimation.

Arsenic release from Fe/Mn oxide-rich (model) soils/sediments - A comparison of single extraction procedures

NASA Astrophysics Data System (ADS)

Vanek, A.; Komarek, M.; Galuskova, I.

2012-04-01

Arsenic extractability in As-modified Fe(III) and Mn(III,IV) oxide-coated sands was tested using five widely used 2-h single extraction procedures: deionised water, 0.01 M CaCl2, 1 M NH4NO3, 0.1 M Na2HPO4 and 0.005 DTPA. In general, the highest As recoveries reaching 39-50% of total As concentration were observed for all extracting media in the birnessite (delta-MnO2) system, indicating relatively weak adsorption of As onto the Mn oxides. The Na2HPO4 extracts from the Fe oxide systems (i.e., associated with ferrihydrite and goethite) were highest in As, accounting for up to 34% of total As amount. Surprisingly, comparable recoveries of As (14-20%) yielded deionised water, CaCl2, NH4NO3, DTPA as extracting media for both ferrihydrite and goethite coatings. Deionised water and Na2HPO4 extractions are suggested for quick estimation of easily soluble, exchangeable and/or specifically adsorbed As in real soil/sediment samples.

Seasonal changes of the mineral contents in the rumen of wild Yeso sika deer (Cervus nippon yesoensis).

PubMed

Hayashida, Maki; Souma, Kousaku; Hanagata, Osamu; Okamoto, Masayo; Masuko, Takayoshi

2012-03-01

The rumen contents were collected from 36 wild Yeso sika deer (Cervus nippon yesoensis) captured by deer culling or by hunting in the spring, summer, autumn and winter in Hokkaido, Japan. Botanical classification was conducted, and the contents of mineral (calcium (Ca), phosphorus (P), potassium (K), sodium (Na), iron (Fe), copper (Cu) and zinc (Zn)) were measured. The animals were captured around pastures or fallow field areas in the Kushiro area. The rumen contents consisted of grasses and Sasa sp. leaves regardless of the season. Leaves and bark were ingested in the spring, autumn and winter. The macro-mineral contents in the rumen showed seasonal changes. In the summer, the Ca, K and P contents were high, and the Na content was low. There were no seasonal changes in the Fe content. The P, Na and Fe contents were higher than the animals' requirements. In a future survey, it is needed to determine the mineral contents of the food ingested by wild Yeso sika deer. © 2011 The Authors. Animal Science Journal © 2011 Japanese Society of Animal Science.

[Analysis of changes in minerals contents during cider fermentation process by inductively coupled plasma mass spectrometry].

PubMed

Ye, Meng-qi; Yue, Tian-li; Gao, Zhen-peng; Yuan, Ya-hong; Nie, Gang

2015-01-01

The changes in mineral elements during cider fermentation process were determined using ICP-MS. The results showed that the main minerals in the fermentation liquor included K, Na, Ca, Mg, Fe, Mn, Zn, Cu, Sr and B. The content of K was the highest in both the apple juice and the cider, being 1 853. 83 and 1 654. 38 mg . L-1 respectively. The content of minerals was in dynamic changes along with the fermentation process. As a whole, during 72-120 h and 144-216 h, most of the minerals contents underwent great fluctuation. Especially when fermented for 192 h, the content of most of the minerals reached peak value or valley value. The content of Fe and Zn achieved their peak value, while the content of K, Na, Ca, Mg, Mn and B achieved valley value. But during the following 24 h, the content of minerals underwent a sharp reversal. After fermentation, the content of K, Mg, Cu, Zn and B decreased significantly, while the content of Na, Ca, Mn, Fe and Sr did not change significantly. The correlational analysis was conducted to evaluate the correlation between the mineral elements, and the result showed that the correlation between Ca and Mn was the most significant, with the correlation index reaching 0. 924. The information of this study will supply sufficient data for the fermentation process control and quality improvement of cider.

Ferric iron partitioning between plagioclase and silicate liquid: thermodynamics and petrological applications

NASA Astrophysics Data System (ADS)

Sugawara, Toru

2001-06-01

A series of Fe and Mg partition experiments between plagioclase and silicate liquid were performed in the system SiO2-Al2O3-Fe2O3-FeO-MgO-CaO-Na2O under oxygen fugacities from below the IW buffer up to that of air. A thermodynamic model of plagioclase solid solution for the (CaAl,NaSi,KSi)(Fe3+,Al3+)Si2O8-Ca(Fe2+,Mg)Si3O8 system is proposed and is calibrated by regression analysis based on new and previously reported experimental data of Fe and Mg partitioning between plagioclase and silicate liquid, and reported thermodynamic properties of end members, ternary feldspar and silicate liquid. Using the derived thermodynamic model, FeOt, MgO content and Mg/(Fet+Mg) in plagioclase can be predicted from liquid composition with standard deviations of +/-0.34 wt% (relative error =9%) and +/-0.08 wt% (14%) and +/-0.7 (8%) respectively. Calculated Fe3+-Al exchange chemical potentials of plagioclase, $μ { Fe{ 3 + } ( {Al} ){ - 1} }{ Pl} agree with those calculated using reported thermodynamic models for multicomponent spinel, μ { Fe{ 3 + } ( {Al} ){ - 1} }{ Sp} and clinopyroxene, μ { Fe{ 3 + } ( {Al} ){ - 1} }{ Cpx} $ . The FeOt content of plagioclase coexisting with spinel or clinopyroxene is affected by Fe3+/(Fe3++Al) and Mg/(Fe+Mg) of spinel or clinopyroxene and temperature, while it is independent of the anorthite content of plagioclase. Three oxygen barometers based on the proposed model are investigated. Although the oxygen fugacities predicted by the plagioclase-liquid oxygen barometer are scattered, this study found that plagioclase-spinel-clinopyroxene-oxygen and plagioclase-olivine-oxygen equilibria can be used as practical oxygen barometers. As a petrological application, prediction of plagioclase composition and fO2 are carried out for the Upper Zone of the Skaergaard intrusion. The estimated oxygen fugacities are well below QFM buffer and consistent with the estimation of oxidization states in previous studies.

Ultrabasic-basic change over primary inclusions in lower-mantle diamonds: Mineralogical and experimental evidence for crucial role of stishovite paradox

NASA Astrophysics Data System (ADS)

Litvin, Yuriy; Spivak, Anna

2017-04-01

Melting relations of the lower-mantle magmatic system MgO - FeO - CaO - SiO2 are characterized by peritectic reaction of bridgmanite (Mg,Fe)SiO3 and melt with formation of Fe-rich phases of periclase-wustite solid solutions (MgO•FeO)ss and stishovite SiO2. The reaction proceeds also in melts-solutions of lower-mantle diamond-parental system MgO - FeO - CaO - SiO2 - (Mg-Fe-Ca-Na-carbonate) - C. Xenoliths of lower mantle rocks were never found among the deep mantle derived materials. Estimation of lower-mantle mineralogy as ferropericlase+ bridgmanite+ Ca-perovskite association is inferred from high-pressure subsolidus experiments with ultrabasic pyrolite composition (Akaogi, 2007). The paradoxical in situ paragenesis of stishovite and ferropericlase as primary inclusions in lower-mantle diamonds (Kaminsky, 2012) takes its explanation from the bridgmanite peritectic reaction (effect of "stishovite paradox") (Litvin et al., 2014). Based on the data for inclusions, physico-chemical study on syngenesis of diamonds and primary inclusions has experimentally revealed the ferropericlase-bridgmanite-Ca-perovskite-stishovite-magnesiowustite-(Mg-Fe-Ca-Na-carbonate)-carbon compositions of the lower-mantle diamond-forming system .(Litvin et al., 2016). The generalized diagram of diamong-forming media characterizes the variable compositions of growths melts for diamonds and paragenetic phases and their genetic relationships with lower mantle matter, and it is the reason for genetic classifying primary inclusions. Fractional ultrabasic-basic evolution and continuous paragenetic transition from ultrabasic bridgmanite-ferropericlase to basic stishovite-magnesiowustite assemblages in the of lower-mantle diamond-parental melts-solutions are providing by the physico-chemical mechanism of stishovite paradox. References Akaogi M. (2007). Phase transformations of minerals in the transition zone and upper part of the lower mantle. In Advances in High-Pressure Mineralogy (Ohtani E., ed.). Geol. Soc. Am. Spec. Paper 421, 1-13. Kaminsky F.V. (2012). Mineralogy of the lower mantle: a review of "supper-deep" mineral inclusions in diamonds. Earth Sci. Rev. 110, 127-147. Litvin Yu.A., Spivak A.V., Solopova N.A., Dubrovinsky L.S. (2014). On origin of lower-mantle diamonds and their primary inclusions. Phys. Earth Planet. Inter. 228, 176-185. Litvin Yu.A., Spivak A.V., Dubrovinsky L.S. (2016). Magmatic evolution of the material of the Earth's lower mantle: stishovite paradox and origin of superdeep diamonds (experiments at 24-26 GPa). Geochemistry Internat. 54(11, 936-947.)

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.

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.

Survey on composition and bioconcentration potential of 12 metallic elements in King Bolete (Boletus edulis) mushroom that emerged at 11 spatially distant sites.

PubMed

Falandysz, Jerzy; Frankowska, Aneta; Jarzynska, Grazyna; Dryzałowska, Anna; Kojta, Anna K; Zhang, Dan

2011-01-01

This paper provides data on baseline concentrations, interrelationships and bioconcentration potential of 12 metallic elements by King Bolete collected from 11 spatially distant sites across Poland. There are significant differences in concentrations of metals (Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Sr, Zn) and their bioconcentration potential in King Bolete Boletus edulis at 11 spatially distant sites surveyed across Poland. These have resulted from significant geographical differences in trace metal concentrations in a layer (0-10 cm) of organic and mineral soil underneath to fruiting bodies and possible local bioavailabilities of macro- (Ca, K, Mg, Na) and trace metals (Al, Ba, Cd, Cu, Fe, Mn, Sr, Zn) to King Bolete. The use of highly appreciated wild-grown edible King Bolete mushroom has established a baseline measure of regional minerals status, heavy metals pollution and assessment of intake rates for wild mushroom dish fanciers against which future changes can be compared. Data on Cd, Cu and Zn from this study and from literature search can be useful to set the maximum limit of these metals in King Bolete collected from uncontaminated (background) areas. In this report also reviewed are data on Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Sr and Zn accumulation in King Bolete.

The composition of pigeon peas (Cajanus cajan (L.) Millsp.) grown in Botswana.

PubMed

Amarteifio, J O; Munthali, D C; Karikari, S K; Morake, T K

2002-01-01

This study investigated the composition of pigeon peas (Cajanus cajan), grown at Sebele, Botswana. The raw seeds of six varieties were analyzed for dry matter, crude fat, protein, fiber, and ash, using Association of Official Analytical Chemists procedures. Major minerals, Ca, K, P, Mg, Na and trace minerals, Cu, Fe and Zn were also assessed. The range of nutrient contents obtained were: dry matter 86.6-88.0%, crude protein 19.0-21.7%, crude fat 1.2-1.3%, crude fiber 9.8-13.0%, and ash 3.9-4.3%. Minerals ranges (mg/100 g dry matter) were: K 1845-1941, P 163-293, Ca 120-167, Mg 113-127, Na 11.3-12.0, Zn 7.2-8.2, Fe 2.5-4.7 and Cu 1.6-1.8. There were no significant differences in Na among the six varieties (p > 0.05). For the other components, varietal differences (p < 0.05) were observed. The values obtained for the dry matter, crude protein, fat, ash, Ca, Cu, Fe, and Mg were similar to those in pigeon peas grown elsewhere, while those for crude fiber and Zn were higher. In general, the composition of pigeon peas compared favorably with those of other legumes such as Bambara groundnut (Vigna subterranea). The levels of crude protein, crude fiber, K, Ca, P and Mg indicated that pigeon peas could be valuable in the diet of the people of Botswana. This crop would positively contribute protein in the diet and the diversification of agricultural produce.

Biomineralogy of human urinary calculi (kidney stones) from some geographic regions of Sri Lanka.

PubMed

Chandrajith, Rohana; Wijewardana, Geethika; Dissanayake, C B; Abeygunasekara, Anurudha

2006-08-01

Kidney stones (urinary calculi) have become a global scourge since it has been recognized as one of the most painful medical problems. Primary causative factors for the formation of these stones are not clearly understood, though they are suspected to have a direct relationship to the composition of urine, which is mainly governed by diet and drinking water. Sixty nine urinary calculi samples which were collected from stone removal surgeries were analyzed chemically for their Na, K, Ca, Mg, Cu, Zn, Pb, Fe and phosphate contents. Structural and mineralogical properties of stones were studied by XRD and FT-IR methods. The mean contents of trace elements were 1348 mg kg(-1) (Na); 294 mg kg(-1) (K); 32% (Ca); 1426 mg kg(-1) (Mg); 8.39 mg kg(-1) (Mn); 258 mg kg(-1) (Fe); 67 mg kg(-1) (Cu); 675 mg kg(-1) (Zn); 69 mg kg(-1) (Pb); and 1.93% (PO (4) (3-) ). The major crystalline constituent in the calculi of Sri Lanka is calcium oxalate monohydrate. Principal component analysis was used to identify the multi element relationships in kidney stones. Three components were extracted and the first component represents positively correlated Na-K-Mg-PO (4) (3-) whereas the second components represent the larger positively weighted Fe-Cu-Pb. Ca-Zn correlated positively in the third component in which Mn-Cu correlated negatively. This study indicates that during the crystallization of human urinary stones, Ca shows more affinity towards oxalates whereas other alkali and alkaline earths precipitate with phosphates.

Chemical composition and evolution of tourmaline-supergroup minerals from the Sb hydrothermal veins in Rožňava area, Western Carpathians, Slovakia

NASA Astrophysics Data System (ADS)

Bačík, Peter; Dikej, Jakub; Fridrichová, Jana; Miglierini, Marcel; Števko, Martin

2017-09-01

Tourmaline-supergroup minerals are common gangue minerals in Sb-hydrothermal veins on Betliar - Straková, Čučma - Gabriela and Rožňava - Peter-Pavol vein deposits in the Rožňava area, Slovakia. Tourmaline-supergroup minerals form relatively large prismatic to radial aggregates of parallel black to greyish-black crystals. Tourmaline-supergroup minerals from Betliar - Straková and Rožňava - Peter-Pavol are almost homogeneous with intermediate schorl-dravite composition. Čučma - Gabriela tourmaline have distinct zoning with massive core of the schorlitic-to-feruvitic shifting to schorlitic-to-dravitic composition, and dravitic to magnesio-foititic rim. The tourmaline composition is influenced by two main substitutions, namely Ca(Mg,Fe)Na-1Al-1 and X □AlNa-1(Mg,Fe)-1. Betliar - Straková and Rožňava - Peter-Pavol tourmaline-supergroup minerals exhibit only small extents of the X □AlNa-1(Mg,Fe)-1 substitution. This substitution shifts the composition to magnesio-foitite in Čučma - Gabriela tourmaline. The decrease of Al in the core of Čučma - Gabriela tourmaline crystals is caused by extensive Ca(Mg,Fe)Na-1Al-1 substitution. The unit-cell dimensions of all investigated tourmaline-supergroup minerals indicate an octahedral disorder with the Z (Fe3++Mg) proportion calculated from empirical equations varying between 0.85 and 0.87 apfu (atoms per formula unit). Based on Mössbauer spectra, the Z Fe3+ content varied between 0.25 apfu in Betliar - Straková tourmaline and 0.45 apfu in Čučma - Gabriela sample. Based on Fe/(Fe + Mg) ratio, Betliar - Straková tourmaline is slightly enriched in Fe compared to Rožňava - Peter-Pavol, suggesting the impact of the host-rock composition; first are grown in Fe-richer acidic metarhyolitic rocks, latter in metapelites. In Čučma - Gabriela, the variations in Fe/(Fe + Mg) are very likely reflecting the change in fluid composition. Magnesio-foitite is the product of second-stage crystallization forming rims and crack fills. The relatively low Fe3+/Fe2+ ratio suggests only minor proportion of meteoric fluids forming tourmaline.

Mineral Composition of Wild and Cultivated Blueberries.

PubMed

Dróżdż, Paulina; Šėžienė, Vaida; Pyrzynska, Krystyna

2018-01-01

The concentrations of 13 elements (Al, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn) were determined in several samples of native (wild) naturally growing and cultivated blueberry fruits. The total metal contents after mineralization were analyzed by inductively coupled plasma optical emission spectrometry. Reliability of the procedure was checked by the analysis of the certified reference materials Mixed Polish Herbs (INGT-MPH-2) and Leaves of Poplar (NCS DC 73350). In the fruits collected in the forest (wild blueberries), higher contents of Ca, Na, and Mg as well as Mn and Zn were observed. Similar levels of Cu, Cr, Fe, and Ni were detected in both wild-growing and cultivated plants. The significantly higher content of Fe and Cd in cultivated blueberries was connected with the content of these metals in soil samples collected from the same places. The metal extraction efficiency by hot water varied widely for the different blueberries (wild or cultivated) as well as their form (fresh or dried).

The structural and electronic properties of metal atoms adsorbed on graphene

NASA Astrophysics Data System (ADS)

Liu, Wenjiang; Zhang, Cheng; Deng, Mingsen; Cai, Shaohong

2017-09-01

Based on density functional theory (DFT), we studied the structural and electronic properties of seven different metal atoms adsorbed on graphene (M + graphene). The geometries, adsorption energies, density of states (DOS), band structures, electronic dipole moment, magnetic moment and work function (WF) of M + graphene were calculated. The adsorption energies ΔE indicated that Li, Na, K, Ca and Fe adsorbed on graphene were tending to form stable structures. However, diffusion would occur on Cu and Ag adsorbed on graphene. In addition, the electronic structure near the Fermi level of graphene was significantly affected by Fe (Cu and Ag), compared with Li (Na, K and Ca). The electronic dipole moment and magnetic moment of M + graphene were sensitive to the adsorbed metal atoms. Moreover, we found electropositive (electronegative) adsorption can decrease (increase) the WF of the surface. Specially, the WF of Ag + graphene and Fe + graphene would increase because surface dipole moment make a contribution to electron.

Electron Spectroscopy Studies of Iron, Iron Sulfides and Supported Iron Surfaces: Chemisorption of Simple Gases.

NASA Astrophysics Data System (ADS)

Lee, Yiu Chung

EELS was used to investigate the chemisorption of oxygen and carbon on iron. The EELS spectra of oxidized iron show characteristic features with strong enhancement of the interband transitions involving the Fe 3d band (4.6 and 7.5 eV) and moderate enhancement of the M(,2,3) transition doublet (54.4 and 58.2 eV). The changes in the electron energy loss structures with an overlayer of graphitic or carbidic carbon were investigated. The adsorption and growth of iron on Ni(100) has been studied using the combined techniques of LEED and EELS. Initially iron grows by a layer-by-layer mechanism for the first few layers. High iron coverages result in the observation of complex LEED patterns with satellites around the main (1 x 1) diffraction sports. This is due to the formation of b.c.c. Fe(110) crystallites arranged in domains with different orientations. EELS studies show the presence of three stages in the growth of iron on Ni(100): low-coverage, film-like and bulk-like. Auger and EELS were used to study the iron sulfide (FeS(,2), Fe(,7)S(,8) and FeS) surfaces. A characteristic M(,2,3) VV Auger doublet with a separation of 5.0 eV was observed on the sulfides. An assignment of the electron energy loss peaks was made based on the energy dependence of the loss peaks and previous photoemission results. The effect of argon ion bombardment was studied. Peaks with strong iron and sulfur character were observed. Heating the damaged sulfides results in reconstruction of the sulfide surfaces. The reactions of the sulfides with simple gases, such as H(,2), CO, CH(,4), C(,2)H(,4), NH(,3) and O(,2) were also studied. Using XPS, the chemisorption of SO(,2) on CaO(100) has been studied. The chemical state of sulfur has been identified as that of sulfate. The kinetics of SO(,2) chemisorption on CaO are discussed. The binding states of Fe and Na on CaO were determined to be Fe('2+) and Na('+) respectively. At low Fe or Na coverages (< 0.5 ML), there is a large increase in the rate of sulfate formation at low SO(,2) exposures (< 3 L). This increase is explained by the 'activation' of SO(,2) chemisorption sites by Fe or Na adatoms.

New calibration of Ji - Di clinopyroxene barometer for Eclogites, pyroxenites and peridotites and eclogite - pyroxenite mantle geotherms.

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor; Vishnyakova, Elena

2010-05-01

Checking the universe clinopyroxene JD-Di barometer on the experimental system showed that it better to use the separate schemes for the eclogite and peridotite systems. The clinopyroxene barometer based on the internal exchange of Jd-Di components for the Al. It allow using the temperature calculated with the (Krogh, 1988) method for the The barometer was calibrated on the 200 experimental runs for the eclogitic system (Yaxley,Brey,2004; Spandler ea, 2008; Konzett ea, 2008; Hanrahan ea, 2009 and references there in). It reproduces the pressure range to 120 kbar with the r= 0.91 (S=8) for 180 experimental runs. P(Ash2010 Ecl)=0.32 (1-0.215*Na/Al+0.012*Fe/Na)*Kd^3/4*ToK/(1+Fe)*(1+5*Fe)- 35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-xx(2,8))*10+xx(2,9)/xx(2,3)* ToK /200-1.5 P1=(0.00004*P^3-0.0091*P^2+1.3936*P)*1.05 Where KD = Na*Mg/xAlCr*/Ca; XAlCr= Al+Cr+4*Ti-K-(Fe-0.21)*0.75 The tests on the natural associations form the eclogitic xenoliths with and without the diamonds and omphacite diamond inclusions (Taylor ea, 2006; Shatsky ea, 2008; Jacob ea, 2009) have shown very good agreement with the position of the Graphite -Diamond (Kennedy, Kennedy, 1977) boundary and to the conductive geotherms which are close to 34-36mvm-2 geotherms while for the South Africa they are more close to 40mvm-2 geotherms. For the zonal omphacites it produces the range of the nearly equal pressures or more rarely advective paths. The levels of the maximum enrichments in eclogites which are close to 50-60 kabr beneath 360ma Siberian kimberlites coincides with the levels of heating according to the monomineral and polymineral thermobarometry. South Africa eclogite geotherms often split into 2-3 branches: subductional (35) conductive (40) for Paleozoic-Mesozoic mantle lithosphere and the hottest advective close o 45 mv/m-2. For the pyroxenite compositions the barometer was rearranged to by the adding the temperature influence on Al , Ta, Fe exactly in KD as following: P(Ash2010 Per-Pxt)=0.275*(1-0.17*Na/Al+0.0115*Fe/Na)*Kd^3/4*ToK/(1+Fe)* (1+5*Fe*(ToK-600)/50)-35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-xx(2,8))*10+xx(2,9)/xx(2,3)* ToK /300-4*(Fe*33.2-4) -(Al-5.5)*( ToK -1300)/70-( ToK -1200)*0.015 with the second correction P=P*0.65+10+Mg*Al*( ToK -1400)/500 Where KD = Na*Mg/xAlCr*/Ca; XAlCr= Al*((T0-800)/800)**0.25+Cr-K+(4*Ti-0.0125)/(T0-600)*400+(Fe-0.21)*(T0-600)/14000 This equations reproduces the experimental pressures for 300 experimental runs with the R=0.84 and for the best set of the experimental data (Walter, 1999; Taylor ea 1998; Brey Kohler, 1990; 2009) with the E=0.95 (s=7) within the 100 kbar interval. They allow to work with the wide range of the pyroxenite compositions giving the practically coinciding PT parameters with the pressures determined for ilmenites and chromites as well as the (Brey, Kohler, 1900) pressure estimates. The PT parameters reconstructed for the mantle lithosphere beneath > 120 pipes from Yakutia , Baltica, Africa , North America and other world wide kimberlites have shown very good coincidence with the estimates from the other methods of monomineral (Nimis, Taylor, 2000; McGregor, 1974; Ashchepkov ea. 2009 ) and Gar-Opx barometers (Brey, Kohler, 1900; Nickel, Green, 1975). For the garnet and spinel xenoliths of the alkali basalts representing fertile or regenerated peridotites with high Al content of the clinopyroxenes the modified equation allows to determine the pressures together for megacrysts, pyroxeniets and peridotites using the following equation P=0.035*Kd*ToK)/(1+3.5*Fe)- 50*ln(1273/(ToK-100)*(Al+5*Na-Ti+2*Cr) -(Na-0.050)*(ToK-1200)*(Ca-0.85)/7000+5 Where KD = Na*Mg/xAlCr*/Ca; xAlCr= (Al+Si-2)*((ToK-700)/900)^0.35+Cr+Fe3-K +(4*Ti-0.0125)/(ToK-600)*700 +(Fe-0.21)*(ToK-400)/17000 This equations also very good reproduce the experimental runs in the pressure interval from 10 to 80 kbar but better to 50 kbars (R=0.92) (S=5) for 170 experimental runs (Putirka ea, 1996; Fallon ea, 1999; Taylor ea, 1998; Drapper Green, 1997; Lambart ea 2009) in this pressure range.

Estimation of genetic parameters and detection of quantitative trait loci for minerals in Danish Holstein and Danish Jersey milk.

PubMed

Buitenhuis, Bart; Poulsen, Nina A; Larsen, Lotte B; Sehested, Jakob

2015-05-21

Bovine milk provides important minerals, essential for human nutrition and dairy product quality. For changing the mineral composition of the milk to improve dietary needs in human nutrition and technological properties of milk, a thorough understanding of the genetics underlying milk mineral contents is important. Therefore the aim of this study was to 1) estimate the genetic parameters for individual minerals in Danish Holstein (DH) (n=371) and Danish Jersey (DJ) (n=321) milk, and 2) detect genomic regions associated with mineral content in the milk using a genome-wide association study (GWAS) approach. For DH, high heritabilities were found for Ca (0.72), Zn (0.49), and P (0.46), while for DJ, high heritabilities were found for Ca (0.63), Zn (0.57), and Mg (0.57). Furthermore, intermediate heritabilities were found for Cu in DH, and for K, Na, P and Se in the DJ. The GWAS revealed a total of 649 significant SNP markers detected for Ca (24), Cu (90), Fe (111), Mn (3), Na (1), P (4), Se (12) and Zn (404) in DH, while for DJ, a total of 787 significant SNP markers were detected for Ca (44), Fe (43), K (498), Na (4), Mg (1), P (94) and Zn (3). Comparing the list of significant markers between DH and DJ revealed that the SNP ARS-BFGL-NGS-4939 was common in both breeds for Zn. This SNP marker is closely linked to the DGAT1 gene. Even though we found significant SNP markers on BTA14 in both DH and DJ for Ca, and Fe these significant SNPs did not overlap. The results show that Ca, Zn, P and Mg show high heritabilities. In combination with the GWAS results this opens up possibilities to select for specific minerals in bovine milk.

A comparison of the techniques of PIXE, PIGE and INAA by reference to the elemental analysis of porcine brain samples

NASA Astrophysics Data System (ADS)

Stedman, J. D.; Spyrou, N. M.

1994-12-01

The trace element concentrations in porcine brain samples as determined by particle-induced X-ray emission (PIXE) analysis, instrumental neutron activation analysis (INAA) and particle-induced gamma-ray emission (PIGE) analysis are compared. The matrix composition was determined by Rutherford backscattering (RBS). Al, Si, P, S, Cl, K, Ca, Mn, Fe and Cd were determined by PIXE analysis Na, K, Sc, Fe, Co, Zn, As, Br, Rb, and Cs by INAA and Na, Mg and Fe by PIGE analysis. The bulk elements C, N, O, Na Cl and S were found by RBS analysis. Elemental concentrations are obtained using the comparator method of analysis rather than an absolute method, the validity which is examined by comparing the elemental concentrations obtained in porcine brain using two separate certified reference materials.

Identification of surface terminations of iron pnictides with low-temperature STM/STS

NASA Astrophysics Data System (ADS)

Wang, Jihui; Li, Ang; Ma, Jihua; Wu, Zheng; Yin, Jiaxin; Lv, Bing; Chu, C. W.; Sefat, A.; McGuire, M.; Sales, B.; Mandrus, D.; Zhang, Chenglin; Dai, Pengcheng; Jin, Rongying; Zhang, Jiandi; Plummer, E. W.; Chen, Genfu; Ding, Hong; Pan, Shuheng H.

2013-03-01

The alkaline-earth metal iron pnictide superconductor AEFe2As2 (AE =Ca, Sr, Ba) have been studied extensively with modern surface techniques, such as scanning tunneling microscopy/spectroscopy (STM/STS) and Angle Resolved Photoemission Spectroscopy (ARPES). Yet the surface termination upon cleaving is still controversial. Hence, the interpretation of those results of STM/STS and reconcile with results of other surface techniques tend to be challenging. We have performed a systematic low-temperature STM/STS study on a series of (Ca,Na)Fe2As2, (Ba,K)Fe2As2, Ba(Fe,Co)2As2, and BaFe2(As,P)2. We found that, with cryogenic cleaving method, all three crystalline atomic layers can be revealed and identified. We will discuss their identities and their implications.

Trace elements and metals in farmed sea bass and gilthead bream from Tenerife Island, Spain.

PubMed

Rubio, C; Jalilli, A; Gutiérrez, A J; González-Weller, D; Hernández, F; Melón, E; Burgos, A; Revert, C; Hardisson, A

2011-11-01

The aim of this study was to determine the levels of metals (Ca, K, Na, Mg) and trace metals (Ni, Fe, Cu, Mn, Zn, Pb, Cd) in two fish species (gilthead bream [Sparus aurata] and sea bass [Dicentrarchus labrax]) collected from fish farms located along the coast of Tenerife Island. Ca, K, Na, Mg, Fe, Cu, Zn, and Mn were measured by flame atomic absorption spectrometry, whereas Pb, Cd, and Ni were determined using graphite furnace atomic absorption spectrometry. Mean Fe, Cu, Mn, and Zn contents were 3.09, 0.59, 0.18, and 8.11 mg/kg (wet weight) in S. aurata and 3.20, 0.76, 0.24, and 10.11 mg/kg (wet weight) in D. labrax, respectively. In D. labrax, Ca, K, Na, and Mg levels were 1,955, 2,787, 699.7, and 279.2 mg/kg (wet weight), respectively; in S. aurata, they were 934.7, 3,515, 532.8, and 262.8 mg/kg (wet weight), respectively. The Pb level in S. aurata was 7.28 ± 3.64 μg/kg (wet weight) and, in D. labrax, 4.42 ± 1.56 μg/kg (wet weight). Mean Cd concentrations were 3.33 ± 3.93 and 1.36 ± 1.53 μg/kg (wet weight) for D. labrax and S. aurata, respectively. All Pb and Cd levels measured were well below the accepted European Commission limits, 300 and 50 μg/kg for lead and cadmium, respectively.

Effects of wastewater irrigation on chemical and physical properties of Petroselinum crispum.

PubMed

Keser, Gonca; Buyuk, Gokhan

2012-06-01

The present study was carried out to assess the impact of wastewater on parsley (Petroselinum crispum). The parameters determined for soil were pH, electrical conductivity (EC), soil organic matter (SOM), nutrient elements (Ca, Mg, Na, K, Mn, Cu, Zn, and Fe), and heavy metals (Cd, Cr, Ni, and Pb), while the parameters determined for the plant included pigment content, dry matter, nutrient element, and heavy metals. SOM, EC, and clay contents were higher, and pH was slightly acidic in soil treated with wastewater compared to control soil. The enrichment factors (EF) of the nutrient elements in contaminated soil are in the sequence of Na (2) > Ca (1.32) > Mn = Mg (1.17) > Cu (1.11) > Zn (1.08) > Fe (1.07) > K (0.93), while EF in parsley are Na (6.63) > Ca (1.60) > Mg (1.34) > Zn (1.15) > Fe (0.95) > Cu = K (0.90) > Mn (0.85). Application of wastewater significantly decreased dry matter, while photosynthetic pigment content increased in parsley. The enrichment of the heavy metals is in the sequence: Cd (1.142) > Pb (1.131) > Ni (1.112) > Cr (1.095). P. crispum shows a high transfer factor (TF > 1) for Cd signifying a high mobility of Cd from soil to plant. Thus, although the wastewater irrigation in parsley production aims to produce socioeconomic benefits, study results indicated that municipal wastewater is not suitable for irrigation of parsley because it has negative effects on plant and causes heavy metal accumulation.

Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors.

PubMed

Xu, Qiyong; Townsend, Timothy; Bitton, Gabriel

2011-07-15

Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H(2)S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H(2)S production in landfills results from biological activity, the concept of inhibiting H(2)S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na(2)MoO(4)), ferric chloride (FeCl(3)), and hydrated lime (Ca(OH)(2)) - were evaluated using flask and column experiments. All three agents inhibited H(2)S generation, with Na(2)MoO(4) reducing H(2)S generation by interrupting the biological sulfate reduction process and Ca(OH)(2) providing an unfavorable pH for biological growth. Although FeCl(3) was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H(2)S production in the column experiment was a reduction in pH. Application of both Na(2)MoO(4) and FeCl(3) inhibited H(2)S generation over a long period (over 180 days), but the impact of Ca(OH)(2) decreased with time as the alkalinity it contributed was neutralized by the generated H(2)S. Practical application and potential environmental implications need additional exploration. Copyright © 2011 Elsevier B.V. All rights reserved.

Tetragonal Almandine, (Fe,Mg,Ca,Na)3(Al,Si,Mg)2Si3O12, a New High-Pressure Mineral from the Shergotty Impact on Mars: an Integrated FESEM-EPMA-Synchrotron Diffraction Investigation

NASA Astrophysics Data System (ADS)

Ma, C.; Tschauner, O. D.

2016-12-01

The combination of FESEM-EDS-EBSD, EPMA, and synchrotron microdiffraction is developing into a powerful tool for identification of micron-scale minerals in rocks such as high-pressure phases in shocked meteorites. During a nanomineralogy investigation of the Shergotty meteorite using this approach, we have identified a new shock-induced high-pressure silicate, majoritic almandine with a tetragonal I41/a structure, in an impact melt pocket. The Shergotty meteorite, which fell in the Gaya district, Bihar, India in 1865, is a Martian basaltic shergottite with shock features. Tetragonal almandine in Shergotty occurs as aggregates of subhedral crystals, 0.8 - 2.5 µm in diameter, along with stishovite in the central region of a shock melt pocket, showing an empirical formula of (Fe1.16Ca0.75Mg0.61Na0.42Mn0.03K0.01)(Al1.16Si0.63Mg0.19Ti0.02)Si3O12. Its general formula is (Fe,Mg,Ca,Na)3(Al,Si,Mg)2Si3O12. EBSD indicated this phase has a garnet-related structure. Synchrotron X-ray diffraction revealed that this garnet has actually a tetragonal structure (I41/a) with unit cell dimensions: a = 11.585(9) Å, c = 11.63(4) Å, V = 1561(7) Å3, and Z = 8. Tetragonal almandine is the polymorph of cubic almandine, a new high-pressure garnet mineral, formed by shock metamorphism via the Shergotty impact event on Mars. It apparently crystallized from Fe-rich shock-induced melt under high-pressure and high-temperature conditions.

Fluor-ferro-leakeite, NaNa2(FC2+2Fe3+2Li)Si8O22F2, a new alkali amphibole from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.

USGS Publications Warehouse

Hawthorne, F.C.; Oberti, R.; Ungaretti, L.; Ottolini, L.; Grice, Joel D.; Czamanske, G.K.

1996-01-01

Fluor-ferro-leakeite is a new amphibole species from the Canada Pinabete pluton, Questa, New Mexico, U.S.A.; it occurs in association with quartz, alkali feldspar, acmite, ilmenite, and zircon. It forms as anhedral bluish black crystals elongated along c and up to 1 mm long. It is brittle, H = 6, Dmeas = 3.37 g/cm3, Dcalc = 3.34 g/cm3. In plane-polarized light, it is strongly pleochroic, X = very dark indigo blue, Y = gray blue, Z = yellow green; X ??? c = 10?? (in ??obtuse), Y = b, Z ??? a = 4?? (in ?? obtuse), with absorption X > Y > Z. Fluor-ferro-leakeite is biaxial positive, ?? = 1.675(2), ??= 1.683(2), ?? = 1.694(1); 2V = 87(2)??; dispersion is not visible because of the strong absorption. Fluor-ferro-leakeite is monoclinic, space group C2/m, a = 9.792(1), b = 17.938(1), c = 5.3133(4) A??, ??= 103.87(7)??, V = 906.0(1) A??3, Z = 2. The ten strongest X-ray diffraction lines in the powder pattern are [d(I,hkl)]: 2.710(100,151), 2.536(92,202), 3.404(57,131), 4.481(54,040), 8.426(45,110), 2.985(38,241), 2.585(38,061), 3.122(29,310), 2.165(26,261), and 1.586(25,403). Analysis by a combination of electron microprobe, ion microprobe, and crystal-structure refinement (Hawthorne et al. 1993) gives SiO2 51.12, Al2O3 1.13, TiO2 0.68, Fe2O3 16.73, FeO 8.87, MgO 2.02, MnO 4.51, ZnO 0.57, CaO 0.15, Na2O 9.22, K2O 1.19, Li2O 0.99, F 2.87, H2Ocalc 0.60, sum 99.44 wt%. The formula unit, calculated on the basis of 23 O atoms, is (K0.23Na0.76)(Na1.97Ca0.03)(Mg 0.46Fe2+1.4Mn2+0.59Zn0.07Fe3+1.93-Ti 0.08Al0.02Li0.61])(Si7.81Al 0.19)O22(F1.39OH0.61). A previous crystal-structure refinement (Hawthorne et al. 1993) shows Li to be completely ordered at the M3 site. Fluor-ferro-leakeite, ideally NaNa2(Fe2+2Fe3+2Li)Si8O22F2, is related to leakeite, NaNa2(Mg2Fe3+3Li)Si 8O22(OH)2, by the substitutions Fe2+ ??? Mg and F ??? OH.

Ca-Fe and Alkali-Halide Alteration of an Allende Type B CAI: Aqueous Alteration in Nebular or Asteroidal Settings

NASA Technical Reports Server (NTRS)

Ross, D. K.; Simon, J. I.; Simon, S. B.; Grossman, L.

2012-01-01

Ca-Fe and alkali-halide alteration of CAIs is often attributed to aqueous alteration by fluids circulating on asteroidal parent bodies after the various chondritic components have been assembled, although debate continues about the roles of asteroidal vs. nebular modification processes [1-7]. Here we report de-tailed observations of alteration products in a large Type B2 CAI, TS4 from Allende, one of the oxidized subgroup of CV3s, and propose a speculative model for aqueous alteration of CAIs in a nebular setting. Ca-Fe alteration in this CAI consists predominantly of end-member hedenbergite, end-member andradite, and compositionally variable, magnesian high-Ca pyroxene. These phases are strongly concentrated in an unusual "nodule" enclosed within the interior of the CAI (Fig. 1). The Ca, Fe-rich nodule superficially resembles a clast that pre-dated and was engulfed by the CAI, but closer inspection shows that relic spinel grains are enclosed in the nodule, and corroded CAI primary phases interfinger with the Fe-rich phases at the nodule s margins. This CAI also contains abundant sodalite and nepheline (alkali-halide) alteration that occurs around the rims of the CAI, but also penetrates more deeply into the CAI. The two types of alteration (Ca-Fe and alkali-halide) are adjacent, and very fine-grained Fe-rich phases are associated with sodalite-rich regions. Both types of alteration appear to be replacive; if that is true, it would require substantial introduction of Fe, and transport of elements (Ti, Al and Mg) out of the nodule, and introduction of Na and Cl into alkali-halide rich zones. Parts of the CAI have been extensively metasomatized.

Origin, speciation, and fluxes of trace-element gases at Augustine volcano, Alaska: Insights into magma degassing and fumarolic processes

NASA Astrophysics Data System (ADS)

Symonds, Robert B.; Reed, Mark H.; Rose, William I.

1992-02-01

Thermochemical modeling predicts that trace elements in the Augustine gas are transported from near-surface magma as simple chloride (NaCl, KCl, FeCl 2, ZnCl 2, PbCl 2, CuCl, SbCl 3, LiCl, MnCl 2, NiCl 2, BiCl, SrCl 2), oxychloride (MoO 2Cl 2), sulfide (AsS), and elemental (Cd) gas species. However, Si, Ca, Al, Mg, Ti, V, and Cr are actually more concentrated in solids, beta-quartz (SiO 2), wollastonite (CaSiO 3), anorthite (CaAl 2Si 2O 8), diopside (CaMgSi 2O 6), sphene (CaTiSiO 5), V 2O 3(c), and Cr 2O 3(c), respectively, than in their most abundant gaseous species, SiF 4, CaCl 2, AlF 2O, MgCl 2 TiCl 4, VOCl 3, and CrO 2Cl 2. These computed solids are not degassing products, but reflect contaminants in our gas condensates or possible problems with our modeling due to "missing" gas species in the thermochemical data base. Using the calculated distribution of gas species and the COSPEC SO 2 fluxes, we have estimated the emission rates for many species (e.g., COS, NaCl, KCl, HBr, AsS, CuCl). Such forecasts could be useful to evaluate the effects of these trace species on atmospheric chemistry. Because of the high volatility of metal chlorides (e.g., FeCl 2, NaCl, KCl, MnCl 2, CuCl), the extremely HCl-rich Augustine volcanic gases are favorable for transporting metals from magma. Thermochemical modeling shows that equilibrium degassing of magma near 870°C can account for the concentrations of Fe, Na, K, Mn, Cu, Ni and part of the Mg in the gases escaping from the dome fumaroles on the 1986 lava dome. These calculations also explain why gases escaping from the lower temperature but highly oxidized moat vents on the 1976 lava dome should transport less Fe, Na, K, Mn and Ni, but more Cu; oxidation may also account for the larger concentrations of Zn and Mo in the moat gases. Nonvolatile elements (e.g., Al, Ca, Ti, Si) in the gas condensates came from eroded rock particles that dissolved in our samples or, for Si, from contamination from the silica sampling tube. Only a very small amount of rock contamination occurred (water/rock ratios between 10 4 and 10 6). Erosion is more prevalent in the pyroclastic flow fumaroles than in the summit vents, reflecting physical differences in the fumarole walls: ash vs. lava. Trace element contents of volcanic gases show enormous variability because of differences in the intensive parameters of degassing magma and variable amounts of wall rock erosion in volcanic fumaroles.

Long-term product consistency test of simulated 90-19/Nd HLW glass

NASA Astrophysics Data System (ADS)

Gan, X. Y.; Zhang, Z. T.; Yuan, W. Y.; Wang, L.; Bai, Y.; Ma, H.

2011-01-01

Chemical durability of 90-19/Nd glass, a simulated high-level waste (HLW) glass in contact with the groundwater was investigated with a long-term product consistency test (PCT). Generally, it is difficult to observe the long term property of HLW glass due to the slow corrosion rate in a mild condition. In order to overcome this problem, increased contacting surface ( S/ V = 6000 m -1) and elevated temperature (150 °C) were employed to accelerate the glass corrosion evolution. The micro-morphological characteristics of the glass surface and the secondary minerals formed after the glass alteration were analyzed by SEM-EDS and XRD, and concentrations of elements in the leaching solution were determined by ICP-AES. In our experiments, two types of minerals, which have great impact on glass dissolution, were found to form on 90-19/Nd HLW glass surface when it was subjected to a long-term leaching in the groundwater. One is Mg-Fe-rich phyllosilicates with honeycomb structure; the other is aluminosilicates (zeolites). Mg and Fe in the leaching solution participated in the formation of phyllosilicates. The main components of phyllosilicates in alteration products of 90-19/Nd HLW glass are nontronite (Na 0.3Fe 2Si 4O 10(OH) 2·4H 2O) and montmorillonite (Ca 0.2(Al,Mg) 2Si 4O 10(OH) 2·4H 2O), and those of aluminosilicates are mordenite ((Na 2,K 2,Ca)Al 2Si 10O 24·7H 2O)) and clinoptilolite ((Na,K,Ca) 5Al 6Si 30O 72·18H 2O). Minerals like Ca(Mg)SO 4 and CaCO 3 with low solubility limits are prone to form precipitant on the glass surface. Appearance of the phyllosilicates and aluminosilicates result in the dissolution rate of 90-19/Nd HLW glass resumed, which is increased by several times over the stable rate. As further dissolution of the glass, both B and Na in the glass were found to leach out in borax form.

Ca-Al-rich chondrules and inclusions in ordinary chondrites

NASA Technical Reports Server (NTRS)

Bischoff, A.; Keil, K.

1983-01-01

Ca-Al-rich objects, hitherto mostly found in carbonaceous chondrites, are shown to be widespread, albeit rare, constituents of type 3 ordinary chondrites. Widespread occurrence and textural similarities of Ca-Al-rich chondrules to common, Mg-Fe-rich chondrules suggest that they formed by related processes. It is suggested in this article that Ca-Al-rich chondrules were formed by total melting and crystallization of heterogeneous, submillimeter- to submillimeter-sized dustballs made up of mixtures of high-temperature, Ca-Al-rich and lower-temperature, Na-K-rich components.

CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI

DOE PAGES

Ratzloff, Michael W.; Artz, Jacob H.; Mulder, David W.; ...

2018-05-23

The [FeFe]-hydrogenases ([FeFe] H 2ases) catalyze reversible H 2 activation at the H-cluster, which is composed of a [4Fe-4S] H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe] H) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H 2 bond activation have been proposed. We have examined this question in the [FeFe] H 2ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of H ox ledmore » to formation of H redH + ([4Fe-4S] H 2+-Fe I-Fe I) and H red' ([4Fe-4S] H 1+-Fe II-Fe I), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe] H. Similar μ-CO IR modes were also identified for H redH + of the [FeFe] H 2ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, H hyd. Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed H redH + was converted to H hyd. Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of Hhyd and appearance of H ox, consistent with enzymatic turnover and H 2 formation. The results show for CaI that the μ-CO of [2Fe] H remains bridging for all of the 'H red' states and that H redH + is on pathway to H hyd and H 2 evolution in the catalytic mechanism. Here, this provides a blueprint for designing small molecule catalytic analogs« less

CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI

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

Ratzloff, Michael W.; Artz, Jacob H.; Mulder, David W.

The [FeFe]-hydrogenases ([FeFe] H 2ases) catalyze reversible H 2 activation at the H-cluster, which is composed of a [4Fe-4S] H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe] H) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H 2 bond activation have been proposed. We have examined this question in the [FeFe] H 2ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of H ox ledmore » to formation of H redH + ([4Fe-4S] H 2+-Fe I-Fe I) and H red' ([4Fe-4S] H 1+-Fe II-Fe I), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe] H. Similar μ-CO IR modes were also identified for H redH + of the [FeFe] H 2ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, H hyd. Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed H redH + was converted to H hyd. Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of Hhyd and appearance of H ox, consistent with enzymatic turnover and H 2 formation. The results show for CaI that the μ-CO of [2Fe] H remains bridging for all of the 'H red' states and that H redH + is on pathway to H hyd and H 2 evolution in the catalytic mechanism. Here, this provides a blueprint for designing small molecule catalytic analogs« less

CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI.

PubMed

Ratzloff, Michael W; Artz, Jacob H; Mulder, David W; Collins, Reuben T; Furtak, Thomas E; King, Paul W

2018-06-20

The [FeFe]-hydrogenases ([FeFe] H 2 ases) catalyze reversible H 2 activation at the H-cluster, which is composed of a [4Fe-4S] H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe] H ) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H 2 bond activation have been proposed. We have examined this question in the [FeFe] H 2 ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of H ox led to formation of H red H + ([4Fe-4S] H 2+ -Fe I -Fe I ) and H red ' ([4Fe-4S] H 1+ -Fe II -Fe I ), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe] H . Similar μ-CO IR modes were also identified for H red H + of the [FeFe] H 2 ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, H hyd . Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed H red H + was converted to H hyd . Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of H hyd and appearance of H ox , consistent with enzymatic turnover and H 2 formation. The results show for CaI that the μ-CO of [2Fe] H remains bridging for all of the "H red " states and that H red H + is on pathway to H hyd and H 2 evolution in the catalytic mechanism. These results provide a blueprint for designing small molecule catalytic analogs.

``Amarna blue'' painted on ancient Egyptian pottery

NASA Astrophysics Data System (ADS)

Uda, M.; Nakamura, M.; Yoshimura, S.; Kondo, J.; Saito, M.; Shirai, Y.; Hasegawa, S.; Baba, Y.; Ikeda, K.; Ban, Y.; Matsuo, A.; Tamada, M.; Sunaga, H.; Oshio, H.; Yamashita, D.; Nakajima, Y.; Utaka, T.

2002-04-01

"Amarna blue" pigments (18 Dynasty, c. 1400 BC) painted on pottery fragments were investigated using the PIXE, XRF and XRD methods in laboratories and also using a portable type of X-ray spectrometer at the sites of excavation. On the blue-colored part enrichment of Na, Al, S, Cl, Ca, Mn, Co, Ni and Zn was found using X-ray spectroscopy, and CaSO 4, NaCl and Co(M)Al 2O 4, M denoting Mn, Fe, Ni and Zn, were found by the help of X-ray diffraction. This means that Amarna blue is a mixture of CaSO 4 and Co(M)Al 2O 4, at least in part.

Thermodynamic modeling of non-ideal mineral-fluid equilibria in the system Si-Al-Fe-Mg-Ca-Na-K-H-O-Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

NASA Astrophysics Data System (ADS)

Dolejš, David; Wagner, Thomas

2008-01-01

We present the results of thermodynamic modeling of fluid-rock interaction in the system Si-Al-Fe-Mg-Ca-Na-H-O-Cl using the GEM-Selektor Gibbs free energy minimization code. Combination of non-ideal mixing properties in solids with multicomponent aqueous fluids represents a substantial improvement and it provides increased accuracy over existing modeling strategies. Application to the 10-component system allows us to link fluid composition and speciation with whole-rock mineralogy, mass and volume changes. We have simulated granite-fluid interaction over a wide range of conditions (200-600 °C, 100 MPa, 0-5 m Cl and fluid/rock ratios of 10-2-104) in order to explore composition of magmatic fluids of variable salinity, temperature effects on fluid composition and speciation and to simulate several paths of alteration zoning. At low fluid/rock ratios (f/r) the fluid composition is buffered by the silicate-oxide assemblage and remains close to invariant. This behavior extends to a f/r of 0.1 which exceeds the amount of exsolved magmatic fluids controlled by water solubility in silicate melts. With increasing peraluminosity of the parental granite, the Na-, K- and Fe-bearing fluids become more acidic and the oxidation state increases as a consequence of hydrogen and ferrous iron transfer to the fluid. With decreasing temperature, saline fluids become more Ca- and Na-rich, change from weakly acidic to alkaline, and become significantly more oxidizing. Large variations in Ca/Fe and Ca/Mg ratios in the fluid are a potential geothermometer. The mineral assemblage changes from cordierite-biotite granites through two-mica granites to chlorite-, epidote- and zeolite-bearing rocks. We have carried out three rock-titration simulations: (1) reaction with the 2 m NaCl fluid leads to albitization, chloritization and desilication, reproducing essential features observed in episyenites, (2) infiltration of a high-temperature fluid into the granite at 400 °C leads to hydrolytic alteration commencing with alkali-feldspar breakdown and leading to potassic, phyllic and argillic assemblages; this is associated with reduction and iron metasomatism as observed in nature and (3) interaction with a multicomponent fluid at 600 °C produces sodic-calcic metasomatism. Na, Ca and Fe are the most mobile elements whereas immobility of Al is limited by f/r ∼ 400. All simulations predict a volume decrease by 3.4-5.4%, i.e., porosity formation at f/r < 30. At higher fluid/rock ratios simulation (2) produces a substantial volume increase (59%) due to mineral precipitation, whereas simulation (3) predicts a volume decrease by 49% at the advanced albitization-desilication stage. Volume changes closely correlate with mass changes of SiO2 and are related to silica solubility in fluids. The combined effects of oxygen fugacity, fluid acidity and pH for breakdown of aqueous metal complexes and precipitation of ore minerals were evaluated by means of reduced activity products. Sharp increases in saturation indexes for oxidative breakdown occur at each alteration zone whereas reductive breakdown or involvement of other chloride complexes favor precipitation at high fluid/rock ratios only. Calculations of multicomponent aqueous-solid equilibria at high temperatures and pressures are able to accurately predict rock mineralogy and fluid chemistry and are applicable to diverse reactive flow processes in the Earth's crust.

Thermal infrared emission spectroscopy of the pyroxene mineral series

NASA Astrophysics Data System (ADS)

Hamilton, Victoria E.

2000-04-01

The thermal infrared emissivity spectra of coarse particulate samples of compositions in the pyroxene series display reststrahlen features (absorptions) that distinguish not only orthorhombic from monoclinic structures, but also major end-members within the two structural groups, as well as minerals within solid solution series. The exact number of reststrahlen features observed and their positions are dependent on mineral structure and cation occupancy of the M1 and M2 sites. End-member quadrilateral pyroxenes (Mg2Si2O6-Fe2Si2O6-Ca[Mg,Fe]Si2O6) are easily distinguished from each other and from minerals in the nonquadrilateral series (NaFeSi2O6-Na[Al,Fe]Si2O6-LiAlSi2O6). Furthermore, among quadrilateral pyroxenes, variations in Mg/(Mg+Fe) are linearly correlated with several band locations, as are variations in Ca content in high-Ca clinopyroxenes. In both quadrilateral and nonquadrilateral compositions, Christiansen feature positions are also diagnostic. No correlations with minor constituents (of the order of 0.05 atoms per formula unit) were observed. The detailed spectral characteristics of pyroxenes and their variability as a function of structure and cation occupancy are presented here with determinative curves for the identification of pyroxene composition. These data have important implications for the interpretation of spectral data from both laboratory and remote sensing instruments because they should permit a more detailed determination of pyroxene composition in measured unknown pure mineral and bulk compositions dominated by surface scattering, i.e., all particulates greater than ~65 μm, and solid samples.

Comparison of digestion methods for total elemental analysis of peat and separation of its organic and inorganic components

USGS Publications Warehouse

Papp, C.S.E.; Harms, T.F.

1985-01-01

In order to find the most efficient digestion method for the total elemental recovery in peat, ten samples were subjected to different techniques and analysed for Ca, Mg, Fe, AI, Na, K, Mn, P, Zn, Cu, Li, Cd, Co, Ni, Pb and Si using atomic-absorption spectrophotometry. The most satisfactory procedures were dry ashing followed by hydrofluoric acid treatment and wet digestion using a mixture of hot nitric, perchloric and hydrofluoric acids. The wet digestion offers the advantage of a single decomposition method for the determination of Ca, Mg, Fe, AI, K, Na, Mn, Cu, Li, Zn and P. An alkaline fusion technique was required for the determination of Si. Hydrogen peroxide was used to separate the peat into its organic and inorganic components, leading to the total recovery of the elements for both fractions.

Metal cation exchange reactions of ore minerals in Fe-Mn crusts of the Marcus Wake Rise (Pacific Ocean) in aqueous-salt solutions

NASA Astrophysics Data System (ADS)

Novikov, G. V.; Bogdanova, O. Yu.; Melnikov, M. E.; Drozdova, A. N.; Lobus, N. V.; Shulga, N. A.

2017-12-01

It is shown that the reaction ability of metal cations of ore minerals in Fe-Mn crusts of the Marcus Wake Rise increases in the following manner: (Co2+ < Cu2+ < Ni2+) < (Mg2+ < Mn2+ < K+ ≈ Ca2+ ≈ Na+). The composition of the exchange complex of the ore minerals is constant and includes these metal cations. Ca2+ and Na+ are major contributors to the exchange capacity of the ore minerals. The capacity of the ore minerals by cations of alkali and base metals is 0.43-0.60 and 2.08-2.70 mg-equiv/g, respectively. The exchange capacity of the ore minerals by cations of base metals increases linearly with the increase in the MnO2 content of the crust and does not depend on the geographical locations of the Marcus Wake guyots.

Four reference soil and rock samples for measuring element availability in the Western Energy Regions

USGS Publications Warehouse

Crock, J.G.; Severson, R.C.

1980-01-01

Attaining acceptable precision in extractable element determinations is more difficult than in total element determinations. In total element determinations, dissolution of the sample is qualitatively checked by the clarity of the solution and the absence of residues. These criteria cannot be used for extracts. Possibilities for error are introduced in virtually every step in soil extractions. Therefore, the use of reference materials whose homogeneity and element content are reasonably well known is essential for determination of extractable elements. In this report, estimates of homogeneity and element content are presented for four reference samples. Bulk samples of about 100 kilograms of each sample were ground to pass an 80-mesh sieve. The samples were homogenized and split using a Jones-type splitter. Fourteen splits of each reference sample were analyzed for total content of Ca, Co, Cu, Fe, K, Mg, Mn, Na, and Zn; DTPA-extractable Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn; exchangeable Ca, Mg, K, and Na; cation exchange capacity water-saturation-extractable Ca, Mg, K, Na, C1, and SO4; soil pH; and hot-water-extractable boron. Error measured between splits was small, indicating that the samples were homogenized adequately and that the laboratory procedure provided reproducible results.

Geographical traceability of virgin olive oils from south-western Spain by their multi-elemental composition.

PubMed

Beltrán, María; Sánchez-Astudillo, María; Aparicio, Ramón; García-González, Diego L

2015-02-15

The geographical traceability of virgin olive oil can be controlled by chemical species that are linked to the production area. Trace elements are among these species. The hypothesis is that the transfer of elements from the soil to the oil is subjected to minor variations and therefore this chemical information can be used for geographical traceability. In order to confirm this hypothesis, the trace elements of virgin olive oils from south-western Spain were analysed, and the same elements were determined in the corresponding olive-pomaces and soils. The differences in the concentration were studied according to cultivars and locations. Results show some coincidences in the selection of elements in soils (W, Fe, Na), olive-pomace (W, Fe, Na, Mg, Mn, Ca, Ba, Li) and olive oils (W, Fe, Mg, Mn, Ca, Ba, Li, Bi), which supports their utility in traceability. In the case of olive oils, 93% of the samples were correctly classified in their geographical origins (96% for Beas, 77% for Gibraleón, 91% for Niebla, and 100% for Sanlúcar de Guadiana). Copyright © 2014 Elsevier Ltd. All rights reserved.

Anode materials for lithium ion batteries

DOEpatents

Abouimrane, Ali; Amine, Khalil

2017-04-11

An electrochemical device includes a composite material of general Formula (1-x)J-(x)Q wherein: J is a metal carbon alloy of formula Sn.sub.zSi.sub.z'Met.sub.wMet'.sub.w'C.sub.t; Q is a metal oxide of formula A.sub..gamma.M.sub..alpha.M'.sub..alpha.'O.sub..beta.; and wherein: A is Li, Na, or K; M and M' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; Met and Met' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; 0

Bhasmas: unique ayurvedic metallic-herbal preparations, chemical characterization.

PubMed

Kumar, A; Nair, A G C; Reddy, A V R; Garg, A N

2006-03-01

Bhasmas are unique Ayurvedic metallic preparations with herbal juices/fruits, known in the Indian subcontinent since the seventh century BC and widely recommended for treatment of a variety of chronic ailments. Twenty bhasmas based on calcium, iron, zinc, mercury, silver, potassium, arsenic, copper, tin, and gemstones were analyzed for up to 18 elements by instrumental neutron activation analysis, including their C, H, N, and S contents. In addition to the major constituent element found at % level, several other essential elements such as Na, K, Ca, Mg, V, Mn, Fe, Cu, and Zn have also been found in microg/g amounts and ultratrace (ng/g) amounts of Au and Co. These seem to remain chelated with organic ligands derived from medicinal herbs. The bhasmas are biologically produced nanoparticles and are taken along with milk, butter, honey, or ghee (a preparation from milk); thus, this makes these elements easily assimilable, eliminating their harmful effects and enhancing their biocompatibility. Siddha Makaradhwaja, a mercury preparation is found to be stoichiometrically HgS without any traces of any other element. Similarly, Swet Parpati is stoichiometrically KNO3 but is found to have Mn, Cu, Zn, Na, P, and Cl as well. An attempt has been made to correlate the metallic contents with their medicinal importance. Na and K, the two electrolytic elements, seem to be well correlated, although K/Na varies in a wide range from 0.06 to 95, with specifically low values for Ca-, Fe-, and Zn-based bhasmas. K/P also varies in a wide range from 0.23 to 12, although for most bhasmas (n = 12), it is 2.3 +/- 1.2. Further, Fe/Mn is linearly correlated (r = 0.96) with Fe in nine noniron bhasmas.

[Determination of 22 inorganic elements in different parts of Lantana camara by ICP-OES].

PubMed

Zhou, Wei-ming; Wang, Ru-yi; Chen, Liu-sheng; Huang, Chuan-bin

2014-09-01

To determine the contents of 22 inorganic elements in different parts of Lantana camara by inductively coupled plasma optical emission spectroscopy (ICP-OES). HNO3-H2 02 digested system was used to completely decomposed the organic compounds effectually by microwave digestion. 22 inorganic elements such as K, Ca, Mg, Fe, Al, Na, Zn, Mn and Cr were determined by ICP-OES under set up working conditions. The contents of K, Ca and Mg were the most in different parts of Lantana camrnara; The contents of K, Ca, Mg, Mn, Sr and Cu in the leaves of Lantana camara were more than that in the root and the branch. The contents of Fe and Na in the root of Lantana camara were more than that in the leaves and the branch. The contents of Pb and Cd were higher than the national standard and Cr had high content in different parts of Lantana camara. The determination method is quick, easy and accurate with high sensitivity,which can determine the contents of 22 inorganic elements accurately in different parts of Lantana camara.

A molten salt process for producing neodymium and neodymium-iron alloys

NASA Astrophysics Data System (ADS)

Sharma, Ram A.; Seefurth, Randall N.

1989-12-01

The production of low-cost neodymium metal in a stirred tank reactor by the reduction of Nd2O3 with sodium in the presence of CaCl2-KCl-NaCl melts by the overall reaction Nd2O3+3CaCl2+6Na→2Nd+3CaO+6NaCl at ˜750 °C is described. The metal produced is recovered from the salt medium by dissolving it in a Nd-Zn or Nd-Fe alloy pool. In the case of Nd-Zn alloy pools, product yields (percentages of theoretical neodymium produced) in excess of 94 pct are obtained when using salt ratios, i.e., the amounts of salt per gram of neodymium produced, ≥3.5 and excess reductant ≥10 pct. The alloy produced is of high quality, and following vacuum distillation of the zinc, can be used in producing General Motors’ MAGNEQUENCH alloy for permanent magnets. In the case of Nd-Fe pools, the yield is also ˜95 pct with a salt ratio as low as 3.5. The yield is found to depend on the salt composition and salt ratio, and to decrease at salt ratios below 3.25. Stirrer position has little effect on yield, while increasing the temperature and placing fins in the reactor increase the yield. The Nd-Fe alloy produced is of as good quality as that produced using Ca reductant and is suitable for direct use in preparing the MAGNEQUENCH alloy.

Guidance Document: Surface Soils Sampling for Munitions Residues in Military Live Fire Training Ranges: Canadian Protocol

DTIC Science & Technology

2012-12-01

NA Boron B 0.5 NA Cadmium Cd 0.3 22 Calcium Ca 4.0 NA Chromium Cr 0.5 87 Cobalt Co 0.5 300 Copper Cu 0.4 91 Iron Fe 0.6 NA Lead Pb 2.5 600...on their susceptibility to initiation. Primary explosives, which include lead azide, lead styphnate, and mercury fulminate, are highly susceptible...ballistic properties. The degradation of NC leads to substances which speed up the degradation process, or else an autocatalytic reaction. To counteract

Siudaite, Na8(Mn2+ 2Na)Ca6Fe3+ 3Zr3NbSi25O74(OH)2Cl·5H2O: a new eudialyte-group mineral from the Khibiny alkaline massif, Kola Peninsula

NASA Astrophysics Data System (ADS)

Chukanov, Nikita V.; Rastsvetaeva, Ramiza K.; Kruszewski, Łukasz; Aksenov, Sergey M.; Rusakov, Vyacheslav S.; Britvin, Sergey N.; Vozchikova, Svetlana A.

2018-03-01

The new eudialyte-group mineral siudaite, ideally Na8(Mn2+ 2Na)Ca6Fe3+ 3Zr3NbSi25O74(OH)2Cl·5H2O, was discovered in a peralkaline pegmatite situated at the Eveslogchorr Mt., Khibiny alkaline massif, Kola Peninsula, Russia. The associated minerals are aegirine, albite, microcline, nepheline, astrophyllite, and loparite-(Ce). Siudaite forms yellow to brownish-yellow equant anhedral grains up to 1.5 cm across. Its lustre is vitreous, and the streak is white. Cleavage is none observed. The Mohs' hardness is 4½. Density measured by hydrostatic weighing is 2.96(1) g/cm3. Density calculated using the empirical formula is equal to 2.973 g/cm3. Siudaite is nonpleochroic, optically uniaxial, negative, with ω = 1.635(1) and ɛ = 1.626(1) (λ = 589 nm). The IR spectrum is given. The chemical composition of siudaite is (wt%; electron microprobe, H2O determined by HCN analysis): Na2O 8.40, K2O 0.62, CaO 9.81, La2O3 1.03, Ce2O3 1.62, Pr2O3 0.21, Nd2O3 0.29, MnO 6.45, Fe2O3 4.51. TiO2 0.54, ZrO2 11.67, HfO2 0.29, Nb2O5 2.76, SiO2 47.20, Cl 0.54, H2O 3.5, -O = Cl - 0.12, total 99.32. According to Mössbauer spectroscopy data, all iron is trivalent. The empirical formula (based on 24.5 Si atoms pfu, in accordance with structural data) is [Na7.57(H2O)1.43]Σ9(Mn1.11Na0.88Ce0.31La0.20Nd0.05Pr0.04K0.41)Σ3(H2O)1.8(Ca5.46Mn0.54)Σ6(Fe3+ 1.76Mn2+ 1.19)Σ2.95Nb0.65(Ti0.20Si0.50)Σ0.71(Zr2.95Hf0.04Ti0.01)Σ3Si24.00Cl0.47O70(OH)2Cl0.47·1.82H2O. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is trigonal, space group R3m, with a = 14.1885(26) Å, c = 29.831(7) Å, V = 5200.8(23) Å3 and Z = 3. Siudaite is chemically related to georgbarsanovite and is its analogue with Fe3+-dominant M2 site. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 6.38 (60) (-114), 4.29 (55) (-225), 3.389 (47) (131), 3.191 (63) (-228). 2.963 (100) (4-15), 2.843 (99) (-444), 2.577 (49) (3-39). Siudaite is named after the Polish mineralogist and geochemist Rafał Siuda (b. 1975).

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

Comar, C.L.; Lengemann, F.W.; Wasserman, R.H. et al

Research activities during the past 6 years are reviewed. Results are reported for recent studies on adaptation to increased dietary Ca by dairy cows as a factor in the reduction of Sr/sup 90/ content of milk; the testing of a theoretical model of alkaline earth absorption in rats by a comparison of biological discrimination among Ca/sup 47/, Sr/sup 85/, and Ba/sup 133/ in the presence of glucose, lactose, and lysine; the effects of lactose on the intestinal absorption of Ca in rats; a comparison of the ileal absorption of Ca/ sup 47/ and Sr/sup 85/ by rats from solutions withmore » high and low concentrations of stable Ca; determinatione of the Ca, Mg, and total alkaline earth content in mucosal tissue and plasma of normally fed rats, fasted rats, and rats fed a lactose solution; an investigation of non-exchangeable Ca compartments in the plasma of sheep; the effect of lactose and vitamin D on calcification in the rachitic chick; the metabolism and milk content of I/sup 131/ of dairy cows after long-term daily administration of I/sup 131/; the absorption of Fe/sup 59/ in sheep; the development of a method for the estimation of parasitic blood loss in sheep by whole-body counting of Fe/sup 59/ retention; the development of a method for the simultaneous measurement of erythrocyte and plasma volume in sheep using Fe/sup 59/ as a tracer; the concentration of Na/sup 22/, Cl/sup 36/, and C/sup 14/ inulin in rat kidney and counter-current mechanisms for the production of concentrated urine in mammals; the effects of diuretics on the distribution of Na/ sup 22/, Fe/sup 59/-labeled erythrocytes, and I/sup 131/labeled albumin in rat kidneys; the effects of thiamine on nervous response to ultraviolet radiation in frogs and lobsters; the effects of gamma radiation on reproductive capabilities of young male rabbits; and an evaluation of the contamination of the food chain by fallout fission products, with emphasis on Sr/sup 90/, Cs/sup 137/, and I/sup 131/ intake from total diet and individual food items. A list is included of publications resulting from research conducted under this contract. (C.H.)« less

Alteration geochemistry of the volcanic-hosted Dedeninyurdu, Yergen and Fındıklıyar Fe-Cu mineralization at Gökçedoǧan, Çorum-Kargi region, Turkey

NASA Astrophysics Data System (ADS)

Gumus, Lokman; Öztürk, Sercan; Yalçın, Cihan; Abdelnasser, Amr; Hanilçi, Nurullah; Kumral, Mustafa

2016-04-01

This study is to determine the mass/volume gain and loss of the major and trace elements during the alteration processes on Dedeninyurdu, Yergen and Fındıklıyar Fe-Cu mineralizations of the area. Fe-Cu mineralization occurred in the spilitic volcanic a rock of Saraycık Formation is associated with the different types of alteration zones which are pyritization, silicification and sericitization. The study area comprises Bekirli Formation, Saraycık Formation, Beşpınar Formation, and Ilgaz Formation. Saraycık formation consists of spilitic volcanic rocks with pelagic limestone, siltstone and chert. The ore mineralogical data show that the pyrite, chalcopyrite, covellite, hematite, malachite and goethite formed during three phases of mineralization. As well as the geologic and petrographic studies reveal three alteration zones with definite mineral assemblages; phyllic alteration (quartz + sericite + pyrite) that represents the main alteration and mineralized zone; propylitic alteration; and carbonatized sericitic alteration zone. The boundaries between these zones are gradual. Mass balance calculations suggested that the phyllic alteration zone represented by gain in Si, Fe, K, S, and LOI and loss in Mg, Ca, and Na refers to silicification, sericitization and pyritization as well as replacement of Fe-Mg silicate and plagioclase. While, in the propylitic alteration zone, enrichment of Si, Fe, Mg, LOI and S occurred with depletions of Ca, Na, and K reflecting chloritization alteration type. On the other hand, carbonatized sericitic alteration zone shows local gain in Si, CaO and K reflects the occurrence of calc-silicate alteration. All alteration zones contain a large proportion of sulfide minerals (gain in S) with increase in loss on ignition (LOI). Keywords: Alteration geochemistry; Mass balance calculation, Fe-Cu mineralization; phyllic alteration, propylitic alteration.

Melt densities in the CaO-FeO-Fe 2O 3-SiO 2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts

NASA Astrophysics Data System (ADS)

Dingwell, Donald B.; Brearley, Mark

1988-12-01

The densities of 10 melts in the CaO-FeO-Fe 2O 3-SiO 2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO 2, 14 to 76 wt% Fe 2O 3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy. Melt densities range from 2.689 to 3.618 gm/cm 3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe 2O 3 and SiO 2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe 3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe 3+. The volume behavior of melts in this system is significantly different from that in the Na 2O-FeO-Fe 2O 3-SiO 2 system, consistent with the proposal that a proportion of Fe 3+ in melts in the CaO-FeO-Fe 2O 3-SiO 2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence ( e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations. The presence of more than one coordination geometry for Fe 3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted.

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.

Implication of the monomineral eclogite thermobarometry for the reconstruction of the PT conditions and origin of mantle eclogites in the structure of Siberian and other cratons.

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor; Logvinova, Alla; Spetsius, Zdislav; Ntaflos, Theodoros; Ravi, Subramanaian; Vladykin, Nikolai; Stegnitsky, Yuri; Babushkina, Svetlana; Ovchinnikov, Yuri

2016-04-01

Enhanced monomineral thermobarometry for clinopyroxenes and garnet (Ashchepkov et al., 2015) allow reconstruction of thermal conditions for the mantle eclogitic xenoliths and xenocrysts of omphacites and pyrope almandine garnets of eclogitic and megacrystic types. Three common groups according to Dawson,(1977) A. Mg - eclogites; B. common subduction-related basaltic eclogites and C. Na-Fe- rich eclogites. In addition group D compile Ca-Al rich varieties (Spetsius et al., 2008; Viljoen et al., 2010). We subdivided these groups and their positions in mantle lithosphere sections beneath the most studied pipes in Yakutia and most interesting localities Worldwide. Group A including Al-rich and low groups are restites or cumulates from the ancient komatiitic basalts or boninites. The Fe# for olivine in equilibrium is 0.05 -0.11 using melt -solid partition coefficient ~0.33 for Fe (Albarede, 1992). For the group B Fe# of the omphacites are ~ 0.11- 0.23 and they could be only cumulates from melted subducted MORB basalts or reactional products. The higher values of Fe -Na-Al rich group C (Fe# ~0.25-0.4) could relate to the subducted basalts or Al - rich sediments (Spetsius et al., 2008) or Mg-rich crustal rocks which were subducted without much melting. Group D Ca-rich eclogites are commonly low Fe but subduction related varieties (Dongre et al., 2015) could be higher in Fe and Na. Partition coefficients of the trace elements between Gar and Cpx for most mantle eclogites relate to equilibration with the melts and REE patterns show different inclinations, while crustal eclogites which re-equilibrated in the solid state often show the same inclinations. Groups A1: a Cr-bearing group formed after crystallization of partial melts produced by volatile fluxes generated by ancient subduction (Heaman et al., 2006; Smart et al., 2009); A2 - low - Al cumulates and restites from komatiitic melts (Aulbach et al., 2011); A3 - low-Cr group which could be restites (Wyman and Kerrich, 2009) or deep cumulates from tonalite- trondhjemite or Mg-rich boninitic arc magmas (Horodytskyi et al., 2007; Barth et al., 2002); A4 a group derived by crystallization of differentiated protokimberlite melts (Haggerty et al., 1979; Kamenetsky et al., 2009). The largest group B with Fe# (~ 0.15-0.25, moderate in Al and Na values, commonly reveal Eu anomalies. The GrB1 interpreted as subducted metagrabbro close to MORB (Jagoutz et al., 1974; Beard et al., 1996; Pearson, 1995; Snyder et al., 1997) reacted with oceanic water (Neal et al., 1990). Enriched Group B2 eclogites are thought to be products of fluid melting of ancient oceanic crust and interaction with peridotites during subduction (Aulbach et al., 2007). Group B3 eclogites (>3 GPa) may be basaltic cumulates derived from plume or ancient arc magmas in cratonic margins (Wyman and Kerrich, 2009); those near Moho may be eclogitized lower crustal cumulates (Shu et al., 2014). Group B4 eclogites are results of hybridization of subducted basalts with protokimberlite and other plume melts (Shatsky et al., 2008 -2015). High-Fe -Na Group C1 eclogites (Fe# > 0.27) may be subducted Fe- basalts; Ca-enriched varieties may be meta-tonalites or trondhjemites (Group C2) (Barth et al., 2002) and those which are very rich in Al could be metasediments (Group C3) (Mazzone and Haggerty, 1989). High -Ca- Al GrD1 are rare high-Ca and low-Fe varieties, commonly Al-rich and kyanite-bearing (sometimes with coesite) (grosspydites) which may be originally carbonate metasomatites (Smyth, 1977) or metapelites (Liou et al., 2014); Group GrD3 eclogites are high-Ca and moderate-Fe and may be ancient Mg-granites (Barth et al., 2002; Jacob et al., 2003) . According to the thermobarometry GrA eclogites are distributed mostly in the lower (L) and- middle parts of SCLM and correspond to low - temperature thermal gradients. GrB2 eclogites form trends of increasing Fe# for garnets and omphacites with decreasing pressure. This could be due to the progressive melting of subducted basalts (Rosenthal et al., 2014) or an opposite due to crystallization of evolving partial melts from primary eclogites. In USCLM the GrB3 omphacites show reactional trends with decreasing Fe# upward or an opposite progressive rise due to magmatic differentiation. GrC dominate the middle part of the SCLM (3-4 GPa) and mostly correspond to the layer originated in the Early Archean time at 3.5-4.0 GPa possibly due to subduction of the tonalitic crust and related metasediments. CrD1 -rich grosspyditic varieties from India, Siberia and South Africa are relatively low-Fe and Al-rich and possibly are metasomatites or products of interaction of sediments and peridotites. The other Ca- rich varieties most likely are subducted anorthosites or rare granites. Supported by the RFBR grants: 05-05-64718, 03-05-64146, 11 -05-00060, 11-05-91060-PICS, 16-05-00841, 16-05-00860 and projects 77-2, 65-03, 02-05 UIGGM SB RAS and ALROSA Stock Company

Surface-structural Control on Minor Element Zoning and Growth Mechanism in Synthetic Magmatic Clinopyroxene

NASA Astrophysics Data System (ADS)

Paquette, J.; Deakin, M.; Baker, D. R.

2006-12-01

Because in situ observations of actively growing surfaces are technically impractical, our understanding of crystal growth mechanisms at hydrothermal and magmatic conditions lags behind that of minerals that can be grown from aqueous solutions at or near room temperature. Growing silicate minerals from hydrous synthetic carbonate melts offers the opportunity to relate directly minor element incorporation to their surface microtopography. Natural hydrothermal diopside was used to seed experiments in which synthetic clinopyroxene crystals were grown at 800 degrees C and 10 kbars for 24 hours, from alkaline melts modelled after the lavas of the Tanzanian volcano Oldoinyo Lengai. The melts were prepared from Na2CO3, K2CO3, CaCO3, MgCO3 and Fe3O4 reagents. One run was anhydrous and the others contained either 2.5 or 5 wt. % H2O. Euhedral tabular crystals ranging in size from 100 to 300 ìm across were found in all three runs, hand-picked and freed from their carbonate matrix by overnight immersion in dilute acetic acid. The crystals consist of \\{110\\} prism, \\{100\\} and \\{001\\} pinacoids and a \\{111\\} dipyramid. AFM images resolved a distinct surface microtopography on each form: arrays of broad macrosteps on \\{100\\}, lens- shaped islands on \\{001\\} facets and striated fiber-like crystallites on \\{110\\}. EMP analyses of polished grain mounts show that compositional zoning of Na and Fe occurs not only among non-equivalent growth sectors but also within single \\{100\\} sectors. Electron microprobe maps of sequentially polished sections indicate that zoning within \\{100\\} sectors reflects differential uptake of Na and Fe on symmetrically non-equivalent steps. Near the crystal surface, the non- equivalent coeval vicinal faces of growth hillocks on \\{100\\} are either diopside-like, Na.007Ca1.00(Mg0.754Fe2+0.22Mn2+0.013Al_{0.003)Si2.00O6 , or acmitic, Ca0.63Na0.35(Mg0.64Fe3+ 0.36)Al0.01Si1.99O6 in composition. Step-specific incorporation of minor elements in a clinopyroxene face has only been documented once, in a hydrothermal diopside from Orford (Quebec), where Fe(II) and Mn(II) were differentially incorporated on steps oriented parallel to [010] on \\{100\\} faces. This natural example and our synthetic crystals reflect growth regimes where minor element incorporation was limited by surface-structural kinetics rather than diffusion- controlled kinetics. Such step-specific surface-structural control has never been reported in clinopyroxenes grown from silicate melts. Is it present, but more subtle, or do silicate melts promote a significantly different growth regime? Comparing zoning patterns in synthetic silicates grown from carbonate versus silicate melts could put new constraints on current models of element partitioning.

Short and long term modulation of tissue minerals concentrations following oral administration of black cumin (Nigella sativa L.) seed oil to laboratory rats.

PubMed

Basheer, Irum; Qureshi, Irfan Zia

2018-01-15

Nigella sativa, or commonly called black cumin is a small herb of family Ranunculaceae is a well-known medicinal plant but its effects on tissue mineral concentrations of animal bodies is unknown. To study the effect of oral administration of fixed oil of black cumin seeds on tissues mineral content using laboratory rats as experimental model. Experimental animals were exposed to two oral doses of seed oil (60 and 120 ml kg -1 body weight). Short- and long term experiments lasted 24 h and 60 days respectively, with three replicates each. Oil extracted from black cumin seeds was subjected to GC-MS to identify chemical components. Following the wet digestion in nitric acid, samples of whole blood and organs of rats were subjected to atomic absorption spectrophotometry for determination of elements concentrations. Data were compared statistically at p < .05. Compared to control, Cr, Mn, Ni, Cu, Zn showed decrease, whereas Co, Na, Mg and K demonstrated increase, but Ca showed both increase and decrease in most of the tissues upon short term exposure to low and high doses of black cumin oil. During long term exposure, Cr, Fe, Mn, Cu exhibited decrease; Co, Na, Mg and Ca concentrations demonstrated an upregulation, whereas Ni and Zn showed increase and decrease in most of the tissues. Comparison of short term with long term experiments at low dose revealed increases in Fe, Zn, Cu, Mg, K and Ca, a decrease in Cr, Mn, Ni and Cu in most tissues, but both increase and decrease in Na. At high dose, an increase occurred in Fe, Ni, Zn, K, Ca, Mg, a decrease in Cr, while both increase and decrease in Cu, Co and Na concentrations. Our study demonstrates that oral administration of black cumin seeds oil to laboratory rats significantly alters tissue trace elements and electrolytes concentrations. The study appears beneficial but indicates modulatory role of black cumin oil as regards mineral metabolism with far reaching implications in health and disease. Copyright © 2017. Published by Elsevier GmbH.

Variations of uranium concentrations in a multi-aquifer system under the impact of surface water-groundwater interaction

NASA Astrophysics Data System (ADS)

Wu, Ya; Li, Junxia; Wang, Yanxin; Xie, Xianjun

2018-04-01

Understanding uranium (U) mobility is vital to minimizing its concentrations in potential drinking water sources. In this study, we report spatial-seasonal variations in U speciation and concentrations in a multi-aquifer system under the impact of Sanggan River in Datong basin, northern China. Hydrochemical and H, O, Sr isotopic data, thermodynamic calculations, and geochemical modeling are used to investigate the mechanisms of surface water-groundwater mixing-induced mobilization and natural attenuation of U. In the study site, groundwater U concentrations are up to 30.2 μg/L, and exhibit strong spatial-seasonal variations that are related to pH and Eh values, as well as dissolved Ca2+, HCO3-, and Fe(III) concentrations. For the alkaline aquifers of this site (pH 7.02-8.44), U mobilization is due to the formation and desorption of Ca2UO2(CO3)30 and CaUO2(CO3)32- caused by groundwater Ca2+ elevation via mineral weathering and Na-Ca exchange, incorporated U(VI) release from calcite, and U(IV) oxidation by Fe(OH)3. U immobilization is linked to the adsorption of CaUO2(CO3)32- and UO2(CO3)34- shifted from Ca2UO2(CO3)30 because of HCO3- elevation and Ca2+ depletion, U(VI) co-precipitation with calcite, and U(VI) reduction by adsorbed Fe2+ and FeS. Those results are of great significance for the groundwater resource management of this and similar other surface water-groundwater interaction zones.

[Physico-chemical characteristics of ambient particles settling upon leaf surface of six conifers in Beijing].

PubMed

Wang, Lei; Hasi, Eerdun; Liu, Lian-You; Gao, Shang-Yu

2007-03-01

The study on the density of ambient particles settling upon the leaf surface of six conifers in Beijing, the micro-configurations of the leaf surface, and the mineral and element compositions of the particles showed that at the same sites and for the same tree species, the density of the particles settling upon leaf surface increased with increasing ambient pollution, but for various tree species, it differed significantly, with the sequence of Sabina chinensis and Platycladus orientalis > Cedrus deodara and Pinus bungeana > P. tabulaeformis and Picea koraiensis. Due to the effects of road dust, low height leaf had a larger density of particles. The density of the particles was smaller in summer than in winter because of the rainfall and new leaf growth. The larger the roughness of leaf surface, the larger density of the particles was. In the particles, the overall content of SiO2, CaCO3, CaMg(CO3,), NaCl, 2CaSO4 . H2O, CaSO4 . 2H2O and Fe2O3 was about 10%-30%, and the main minerals were montmorillonite, illite, kaolinite and feldspar. The total content of 21 test elements in the particles reached 16%-37%, among which, Ca, Al, Fe, Mg, K, Na and S occupied 97% or more, while the others were very few and less affected by sampling sites and tree species.

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

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.

Impact of NLTE on research of early chemical enrichment of the dwarf galaxies

NASA Astrophysics Data System (ADS)

Mashonkina, Lyudmila

2015-08-01

The individual stars observed in the dwarf galaxies orbiting the Milky Way are presumably red giants. Their chemical abundances are commonly determined under the classical LTE assumption, despite its validity is questionable for atmospheres of giant, in particular, metal-poor stars. Exactly metal-poor objects are important for understanding the early chemical enrichment processes of the host galaxy and the onset of star formation. We selected a sample of the -4 < [Fe/H] < -2 stars in the dwarf spheroidal (dSph) galaxies Sculptor, Sextans, and Fornax and the ultra-faint galaxies Bootes I and Segue I, with the high-resolution observational data available, and revised abundances of up to 12 chemical species based on the non-local thermodynamic equilibrium (NLTE) line formation. Stellar parameters taken from the literature were checked through the NLTE analysis of lines of iron observed in the two ionisation stages, Fe I and Fe II. For the Scl, Sex, and Fnx stars, with effective temperatures and surface gravities derived from the photometry and known distance (Jablonka et al. 2015; Tafelmeyer et al. 2010), the Fe I/Fe II ionisation equilibrium was found to be fulfilled, when applying a scaling factor of SH = 0.5 to the Drawinian rates of Fe+H collisions. Pronounced NLTE effects were calculated for lines of Na I and Al I resulting in up to 0.5 dex lower [Na/Fe] ratios and up to 0.65 dex higher [Al/Fe] ratios compared with the corresponding LTE values. For the six Scl stars, the scatter of data on Mg/Na is much smaller in NLTE, with the mean [Mg/Na] = 0.61 +- 0.11, than LTE, where [Mg/Na] = 0.42 +- 0.21. We computed a grid of the NLTE abundance corrections for an extensive list of the Ca I, Ti I-Ti II, and Fe I lines in the MARCS models of cool giants, 4000 K <= Teff <= 4750 K, 0.5 <= log g <= 2.5, -4 <= [M/H] <= 0.

How unique is the Udachnaya-East kimberlite? Comparison with kimberlites from the Slave Craton (Canada) and SW Greenland

NASA Astrophysics Data System (ADS)

Kamenetsky, Vadim S.; Kamenetsky, Maya B.; Weiss, Yakov; Navon, Oded; Nielsen, Troels F. D.; Mernagh, Terrence P.

2009-11-01

The origin of alkali carbonates and chlorides in the groundmass of unaltered Udachnaya-East kimberlites in Siberia is still controversial. Contrary to existing dogma that the Udachnaya-East kimberlite was either contaminated by the crustal sediments or platform brines, magmatic origin of the groundmass assemblage has been proposed on the basis of melt immiscibility textures, melt inclusion studies, and strontium and neon isotope compositions. We further tested the idea of alkali- and chlorine enrichment of the kimberlite parental melt by studying olivine-hosted melt inclusions and secondary serpentine in kimberlites from the Slave Craton, Canada (Gahcho Kué, Jericho, Aaron and Leslie pipes) and southern West Greenland (Majuagaa dyke). Host olivine phenocrysts closely resemble groundmass olivine from the Udachnaya-East kimberlite in morphology, compositions (high-Fo, low-Ca), complex zoning with cores of varying shapes and compositions and rims of constant Fo. Melt inclusions in olivine consist of several translucent and opaque daughter phases and vapour bubble(s). The daughter crystals studied in unexposed inclusions by laser Raman spectroscopy and in carefully exposed inclusions by WDS-EDS are represented by Na-K chlorides, calcite, dolomite, magnesite, Ca-Na, Ca-Na-K and Ca-Mg-Ba carbonates, bradleyite Na 3 Mg(CO 3)(PO 4), K-bearing nahpoite Na 2(HPO 4), apatite, phlogopite and tetraferriphlogopite, unidentified sulphates, Fe sulphides, djerfisherite, pyrochlore (Na,Ca) 2Nb 2O 6(OH,F), monticellite, Cr-spinel and Fe-Ti oxides. High abundances of Na, K (e.g., (Na + K)/Ca = 0.15-0.85) and incompatible trace elements in the melt inclusions are confirmed by LA-ICPMS analysis of individual inclusions. Heating experiments show that melting of daughter minerals starts and completes at low temperatures (~ 100 °C and 600 °C, respectively), further reinforcing the similarity with the Udachnaya-East kimberlite. Serpentine minerals replacing olivine in some of the studied kimberlites demonstrate elevated abundances of chlorine (up to 3-4 wt.%), especially in the early generation. Despite heterogeneous distribution of chlorine such abundances are significantly higher than in the serpentine in abyssal and ophiolitic peridotites (< 0.5 wt.%). The groundmass of most kimberlites, including those studied here and altered kimberlites from the Udachnaya pipe, contain no alkali carbonates and chlorides and have low Na 2O (< 0.2 wt.%). We believe that alteration disturbs original melt compositions, with the alkaline elements and chlorine being mostly affected. However, the compositions of melt inclusions and serpentine are indicative of the chemical signature of a parental kimberlite melt. It appears that enrichment in alkalies and chlorine, as seen in unaltered Udachnaya-East kimberlites, is shared by other kimberlites, and thus can be assigned to deep mantle origin.

Orosensory responsiveness to and preference for hydroxide-containing salts in mice.

PubMed

St John, Steven J; Boughter, John D

2009-07-01

Historically, taste researchers have considered the possibility that the gustatory system detects basic compounds, such as those containing the hydroxide ion, but evidence for an "alkaline taste" has not been strong. We found that, in 48 h, 2-bottle preference tests, C3HeB/FeJ (C3) mice showed a preference for Ca(OH)(2), whereas SWR/J (SW) mice showed avoidance. Strain differences were also apparent to NaOH but not CaCl(2). Follow-up studies showed that the strain difference for Ca(OH)(2) was stable over time (Experiment 2) but that C3 and SW mice did not differ in their responses to Ca(OH)(2) or NaOH in brief-access tests, where both mice avoided high concentrations of these compounds (Experiment 3). In order to assess the perceived quality of Ca(OH)(2), mice were tested in 2 taste aversion generalization experiments (Experiments 4 and 5). Aversions to Ca(OH)(2) generalized to NaOH but not CaCl(2) in both strains, suggesting that the generalization was based on the hydroxide ion. Both strains also generalized aversions to quinine, suggesting the possibility that the hydroxide ion has a bitter taste quality to these mice, despite the preference shown by C3 mice to middle concentrations in long-term tests.

Crystal structures of two new low-symmetry calcium-deficient analogs of eudialyte

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

Rastsvetaeva, R. K.; Rozenberg, K. A.; Pekov, I. V.

2006-03-15

The crystal structures of two new low-symmetry (sp. gr. R3) representatives of the eudialyte group from Mont Saint-Hilaire (Quebec, Canada) and the Lovozero massif (Kola Peninsula, Russia) were studied by single-crystal X-ray diffraction analysis and refined to R = 0.068 and 0.054 using 2899 reflections with F > 5{sigma}(F) and 2927 reflections with F > 3{sigma}(F), respectively. The idealized formulas of these representatives are Na{sub 13}(Ca{sub 3}Mn{sub 3})Zr{sub 3}(Fe, Mn){sub 3}({open_square})(Si)[Si{sub 3}O{sub 9}]{sub 2}[Si{sub 9}O{sub 27}]{sub 2}(O, OH, Cl){sub 3} . 2H{sub 2}O and Na{sub 15}(Ca{sub 3}Mn{sub 3})Zr{sub 3}(Fe, Zr){sub 3}(Si)(Si) . [Si{sub 3}O{sub 9}]{sub 2}[Si{sub 9}O{sub 27}]{sub 2}O{sub 2}(OH,more » F, Cl){sub 2} . 2H{sub 2}O. Both minerals are analogs of oneillite and are characterized by a low Ca content. The distinguishing features of the mineral from Quebec are that the M(4) site is essentially vacant (>50%) and Ca atoms occupy one independent site in the six-membered ring, whereas another site is occupied by Mn along with a small impurity of Na. In the mineral from the Lovozero massif, both the M(3) and M(4) sites are occupied predominantly by silicon, while Ca atoms are distributed between both octahedral sites of the six-membered ring, one of these sites being occupied predominantly by Mn.« less

Evaluation of potable groundwater quality in some villages of Adilabad in Andhra Pradesh, India.

PubMed

Rasheed, M A; Radha, B Anu; Rao, P L Srinivasa; Lakshmi, M; Chennaiah, J Bala; Dayal, A M

2012-07-01

Reconnaissance hydrochemical survey was conducted in some villages of Adilabad district, Andhra Pradesh to assess the quality of groundwater, which is mainly used for drinking purpose. The study consists of the determination of physico-chemical properties, trace metals, heavy metals and rare earth elements in water samples. The data showed the variation of the investigated parameters in samples as follows: pH 6.92 to 8.32, EC 192 to 2706 microS cm(-1), TDS 129.18 to 1813.02 ppm. The pH of the waters was within the permissible limits whereas EC and TDS were above the permissible limits of World Health Organization (WHO). Total 27 elements (Li, Be, B, Na, Mg, Al, Si, K, Ca, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba and Pb) were analyzed using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The concentration of elements in water samples ranged between 0.063 to 0.611 mg l(-1) for B, 11.273 to 392 mg l(-)1 for Na, 5.871 to 77.475 mg l(-1) for Mg, 0.035 to 1.905 mg l(-1) for Al, 0.752 to 227.893 mg l(-1) for K, 11.556 to 121.655 mg l(-1) for Ca and 0.076 to 0.669 mg l(-1) for Fe respectively. The concentrations of Na, Mg, Al, K, Ca, and Fe exceeded the permissible limits of WHO and BIS guidelines for drinking water quality. In the present study, Bhimavaram, Kazipalli, Kannepalli and Chennur areas of the Adilabad are especially prone to geogenic contamination. Overall water quality was found unsatisfactory for drinking purposes.

Assessment of groundwater quality in Kashipur Block, Purulia district, West Bengal

NASA Astrophysics Data System (ADS)

Kundu, Anindita; Nag, S. K.

2018-03-01

Hydrogeochemical investigation of groundwater resources of Kashipur Block, Purulia district, West Bengal has been carried out to assess the water quality for domestic and irrigation uses. Twenty groundwater samples were collected and analyzed for pH, electrical conductivity, total dissolved solids, hardness, major anions (CO3 2-, HCO3 -, Cl-, SO4 2-, F-) and cations (Ca2+, Mg2+, Fe2+, Na+, K+). Study results reveal that the groundwater of the area is mostly acidic in nature. The trend amongst average ionic concentrations of cations and anions is Mg2+ > Ca2+ > Na+ > Fe2+ > K+ and Cl- > HCO3 - > CO3 2- > SO4 2- > F- respectively during the post monsoon whereas the trend for cations and anions are Mg2+ > Ca2+> Na+ > K+ > Fe and Cl- > HCO3 - > SO4 2- > F- > CO3 - in pre monsoon session, respectively. To explore the ionic toxicity of the study area, the derived parameters like sodium adsorption ratio, soluble sodium percentage, residual sodium carbonate, magnesium adsorption ratio, Kelly's ratio and permeability index were calculated. The hydro geochemical data suggest that weathering of rock forming minerals along with secondary contributions from agricultural and anthropogenic sources are mainly controlling the groundwater composition of Kashipur Block, Purulia District. According to piper diagram, water samples of most of the area of the block are fresh water and in some areas sulphate rich throughout the year. All samples are distributed to central rock dominance category. Groundwater chemistry of this block is mainly controlled by the interaction existing between the litho units and the percolating water into the subsurface domain. However, the groundwater quality and suitability of this study area can be termed as good to moderate with a few exceptions which have been encountered on a local scale.

Concentration of Minerals in Nectar Honeys from Direct Sale and Retail in Poland.

PubMed

Kędzierska-Matysek, Monika; Florek, Mariusz; Wolanciuk, Anna; Barłowska, Joanna; Litwińczuk, Zygmunt

2018-04-04

The aim of the study was to compare the content of selected minerals in different nectar honeys (acacia, buckwheat, raspberry, linden, rapeseed, and multifloral) available on the Polish market. The degree to which the demand for eight minerals (K, Na, Mg, Ca, Zn, Fe, Mn, Cu) by adults is met by a portion of 100 g of honey was estimated as well. The material consisted of 34 artisanal honeys from direct sale and 34 samples purchased from retail stores. The artisanal honeys contained significantly more K, Mg, and Mn, but significantly less Na and Fe than the honeys purchased from the retail stores. The raspberry honey contained significantly the most K and Ca (1104.7 and 68.8 mg kg -1 ), the multifloral honey contained the most Ca and Mg (68.5 and 48.0 mg kg -1 ), and the buckwheat honey contained the most Zn and Mn (3.97 and 4.96 mg kg -1 ). The highest content of Na was shown in buckwheat and linden honeys (79.1 and 80.0 mg kg -1 ). Consumption of 100 g of honey from direct sale satisfied from 2.5 to 4.5% of the recommended intakes for K and from 10.4 to 17.3% for Mn, while the same portion of honey from retail satisfied from 1.6 to 4.8% for Fe, and from 2.3 to 6.1% for Zn and Cu. The buckwheat honey met to the greatest degree the recommended dietary intakes for Mn (16.5-27.6%), followed by raspberry honey (10.0-16.7%) and multifloral honey (6.9-11.6%).

Effect of lipid peroxidation, antioxidants, macro minerals and trace elements on eczema.

PubMed

Amin, Mohammad Nurul; Liza, Kaniz Fatema; Sarwar, Md Shahid; Ahmed, Jamiuddin; Adnan, Md Tareek; Chowdhury, Manjurul Islam; Hossain, Mohammad Zahid; Islam, Mohammad Safiqul

2015-09-01

The exact etiology and pathogenesis of eczema are not yet fully understood, although different factors are considered as pathogenic mechanisms in the development of eczema. Our study was designed to determine extent of serum lipid peroxidation, antioxidants, macro minerals and trace elements in patients with eczema, and thereby, find any pathophysiological correlation. The study was conducted as a case-control study with 65 eczema patients as cases and 65 normal healthy individuals as controls. Lipid peroxidation was assessed by measuring the serum level of malondialdehyde (MDA). Antioxidants- vitamin A and E concentration was determined by RP-HPLC method whereas vitamin C was evaluated for serum ascorbic acid by UV spectrophotometric method. Serum macro minerals (Na, K, Ca) and trace elements (Zn, Fe) were determined by Atomic Absorption Spectroscopy (AAS). This study found significantly higher level of MDA (p < 0.001) and lower level of antioxidants (p < 0.05) in patients in comparison to the control subjects. Analysis of serum macro minerals (Na, K and Ca) and trace elements (Zn, Fe) found that the mean values of Na, K, Ca, Zn and Fe were 2771.60 ± 75.64, 66.33 ± 3.03, 48.41 ± 2.50, 0.30 ± 0.02 and 0.29 ± 0.009 mg/L for the patient group and 3284.81 ± 34.51, 162.18 ± 3.72, 87.66 ± 2.10, 0.75 ± 0.06 and 0.87 ± 0.06 mg/L for the control group, accordingly. There was a significant difference for all the minerals between the patients and controls (p < 0.001). This study suggests a strong association between the pathogenesis of eczema with the elevated level of MDA and depleted level of antioxidants, macro minerals, and trace elements.

Effects of different concentrations of metal ions on degradation of adenosine triphosphate in common carp (Cyprinus carpio) fillets stored at 4°C: An in vivo study.

PubMed

Li, Dapeng; Qin, Na; Zhang, Longteng; Lv, Jian; Li, Qingzheng; Luo, Yongkang

2016-11-15

The impact of different concentrations of Na(+), K(+), Ca(2+), Mg(2+), Fe(2+), and Zn(2+) on the degradation of adenosine triphosphate (ATP) and the influence of these ions on the activity of adenosine monophosphate deaminase (AMP-deaminase) and acid phosphatase (ACP) in common carp fillets (in vivo) during 4°C storage was examined. The content of ATP, inosine monophosphate (IMP), and hypoxanthine (Hx), and the activity of AMP-deaminase and ACP were determined. Results indicated that the effects of different concentrations of six kinds of metal ions on AMP-deaminase and ACP were not the same. Na(+), K(+), Fe(2+), and Zn(2+) enhanced AMP-deaminase activity, which led to the rapid degradation of ATP and to the generation of a large quantity of IMP within a short time. Ca(2+) and Mg(2+) delayed the change in AMP-deaminase and ACP activity in carp and caused a further delay in the degradation of ATP. Fe(2+) and Zn(2+) inhibited ACP activity, which reduced the decomposition of IMP and the formation of Hx. Copyright © 2016 Elsevier Ltd. All rights reserved.

Stabilizing Fe Nanoparticles in the SmCo 5 Matrix

DOE PAGES

Shen, Bo; Mendoza-Garcia, Adriana; Baker, Sarah E.; ...

2017-08-03

In this paper, we report a new strategy for stabilizing Fe nanoparticles (NPs) in the preparation of SmCo 5–Fe nanocomposites. We coat the presynthesized Fe NPs with SiO 2 and assemble the Fe/SiO 2 NPs with Sm–Co–OH to form a mixture. After reductive annealing at 850 °C in the presence of Ca, we obtain SmCo 5–Fe/SiO 2 composites. Following aqueous NaOH washing and compaction, we produced exchange-coupled SmCo 5–Fe nanocomposites with Fe NPs controlled at 12 nm. In conclusion, our work demonstrates a successful strategy of stabilizing high moment magnetic NPs in a hard magnetic matrix to produce a nanocompositemore » with tunable magnetic properties.« less

Chemical data and statistical interpretations for rocks and ores from the Ranger uranium mine, Northern Territory, Australia

USGS Publications Warehouse

Nash, J. Thomas; Frishman, David

1983-01-01

Analytical results for 61 elements in 370 samples from the Ranger Mine area are reported. Most of the rocks come from drill core in the Ranger No. 1 and Ranger No. 3 deposits, but 20 samples are from unmineralized drill core more than 1 km from ore. Statistical tests show that the elements Mg, Fe, F, Be, Co, Li, Ni, Pb, Sc, Th, Ti, V, CI, As, Br, Au, Ce, Dy, La Sc, Eu, Tb, Yb, and Tb have positive association with uranium, and Si, Ca, Na, K, Sr, Ba, Ce, and Cs have negative association. For most lithologic subsets Mg, Fe, Li, Cr, Ni, Pb, V, Y, Sm, Sc, Eu, and Yb are significantly enriched in ore-bearing rocks, whereas Ca, Na, K, Sr, Ba, Mn, Ce, and Cs are significantly depleted. These results are consistent with petrographic observations on altered rocks. Lithogeochemistry can aid exploration, but for these rocks requires methods that are expensive and not amenable to routine use.

Laser ablation-laser induced breakdown spectroscopy for the measurement of total elemental concentration in soils.

PubMed

Pareja, Jhon; López, Sebastian; Jaramillo, Daniel; Hahn, David W; Molina, Alejandro

2013-04-10

The performances of traditional laser-induced breakdown spectroscopy (LIBS) and laser ablation-LIBS (LA-LIBS) were compared by quantifying the total elemental concentration of potassium in highly heterogeneous solid samples, namely soils. Calibration curves for a set of fifteen samples with a wide range of potassium concentrations were generated. The LA-LIBS approach produced a superior linear response different than the traditional LIBS scheme. The analytical response of LA-LIBS was tested with a large set of different soil samples for the quantification of the total concentration of Fe, Mn, Mg, Ca, Na, and K. Results showed an acceptable linear response for Ca, Fe, Mg, and K while poor signal responses were found for Na and Mn. Signs of remaining matrix effects for the LA-LIBS approach in the case of soil analysis were found and discussed. Finally, some improvements and possibilities for future studies toward quantitative soil analysis with the LA-LIBS technique are suggested.

Particle size dependence of alkali and alkaline earth metal enrichment in marine aerosols from Bermuda

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

Hoffman, E.J.; Hoffman, G.L.; Duce, R.A.

1980-10-20

Three cascade impactor samples were collected from a 20-m-high tower on the southeastern coast of Bermuda. These samples were analyzed for Na, K, Ca, Mg, and Fe by atomic absorption spectrophotometry. When the alkali-alkakine earth metal concentrations are corrected for a soil-derived component, utilizing the atmospheric Fe concentrations, Mg, Ca, and Na are found to be present in the same relative abundances as in seawater for all particle sizes sampled. Potassium also shows no deviation from a bulk seawater composition for particles with radii greater than approx.0.5 ..mu..m. However, excess K above that expected from either a bulk seawater ormore » soil source is observed on particles with radii less than approx.0.5 ..mu..m. While oceanic chemical fractionation processes during bubble bursting may be responsible for this excess small particle K, it is most likely due to long-range transport of K-rich particles of terrestrial vegetative origin.« less

Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses.

PubMed

Ardini, Francisco; Soggia, Francesco; Abelmoschi, Maria Luisa; Magi, Emanuele; Grotti, Marco

2013-01-01

To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP-AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP-MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots.

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...

Code of Federal Regulations, 2012 CFR

2012-01-01

...+05 C-14 4.6E+06 Na-22 1.9E+01 Al-26 1.5E+01 Si-32 4.9E+04 S-35 2.4E+06 Cl-36 5.2E+05 K-40 2.7E+02 Ca-41 9.3E+06 Ca-45 1.1E+06 Sc-46 6.2E+01 Ti-44 1.5E+02 V-49 1.0E+08 Mn-53 7.5E+07 Mn-54 6.5E+01 Fe-55 2.9E+06 Fe-59 1.9E+02 Fe-60 8.1E+03 Co-56 3.9E+01 Co-57 2.3E+02 Co-58 1.3E+02 Co-60 1.7E+01 Ni-59 3.2E...

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...

Code of Federal Regulations, 2013 CFR

2013-01-01

...+05 C-14 4.6E+06 Na-22 1.9E+01 Al-26 1.5E+01 Si-32 4.9E+04 S-35 2.4E+06 Cl-36 5.2E+05 K-40 2.7E+02 Ca-41 9.3E+06 Ca-45 1.1E+06 Sc-46 6.2E+01 Ti-44 1.5E+02 V-49 1.0E+08 Mn-53 7.5E+07 Mn-54 6.5E+01 Fe-55 2.9E+06 Fe-59 1.9E+02 Fe-60 8.1E+03 Co-56 3.9E+01 Co-57 2.3E+02 Co-58 1.3E+02 Co-60 1.7E+01 Ni-59 3.2E...

10 CFR Appendix E to Part 835 - Values for Establishing Sealed Radioactive Source Accountability and Radioactive Material Posting...

Code of Federal Regulations, 2014 CFR

2014-01-01

...+05 C-14 4.6E+06 Na-22 1.9E+01 Al-26 1.5E+01 Si-32 4.9E+04 S-35 2.4E+06 Cl-36 5.2E+05 K-40 2.7E+02 Ca-41 9.3E+06 Ca-45 1.1E+06 Sc-46 6.2E+01 Ti-44 1.5E+02 V-49 1.0E+08 Mn-53 7.5E+07 Mn-54 6.5E+01 Fe-55 2.9E+06 Fe-59 1.9E+02 Fe-60 8.1E+03 Co-56 3.9E+01 Co-57 2.3E+02 Co-58 1.3E+02 Co-60 1.7E+01 Ni-59 3.2E...

Characterization of elemental release during microbe granite interactions at T = 28 °C

NASA Astrophysics Data System (ADS)

Wu, Lingling; Jacobson, Andrew D.; Hausner, Martina

2008-02-01

This study used batch reactors to characterize the mechanisms and rates of elemental release (Al, Ca, K, Mg, Na, F, Fe, P, Sr, and Si) during interaction of a single bacterial species ( Burkholderia fungorum) with granite at T = 28 °C for 35 days. The objective was to evaluate how actively metabolizing heterotrophic bacteria might influence granite weathering on the continents. We supplied glucose as a C source, either NH 4 or NO 3 as N sources, and either dissolved PO 4 or trace apatite in granite as P sources. Cell growth occurred under all experimental conditions. However, solution pH decreased from ˜7 to 4 in NH 4-bearing reactors, whereas pH remained near-neutral in NO 3-bearing reactors. Measurements of dissolved CO 2 and gluconate together with mass-balances for cell growth suggest that pH lowering in NH 4-bearing reactors resulted from gluconic acid release and H + extrusion during NH 4 uptake. In NO 3-bearing reactors, B. fungormum likely produced gluconic acid and consumed H + simultaneously during NO 3 utilization. Over the entire 35-day period, NH 4-bearing biotic reactors yielded the highest release rates for all elements considered. However, chemical analyses of biomass show that bacteria scavenged Na, P, and Sr during growth. Abiotic control reactors followed different reaction paths and experienced much lower elemental release rates compared to biotic reactors. Because release rates inversely correlate with pH, we conclude that proton-promoted dissolution was the dominant reaction mechanism. Solute speciation modeling indicates that formation of Al-F and Fe-F complexes in biotic reactors may have enhanced mineral solubilities and release rates by lowering Al and Fe activities. Mass-balances further reveal that Ca-bearing trace phases (calcite, fluorite, and fluorapatite) provided most of the dissolved Ca, whereas more abundant phases (plagioclase) contributed negligible amounts. Our findings imply that during the incipient stages of granite weathering, heterotrophic bacteria utilizing glucose and NH 4 only moderately elevate silicate weathering reactions that consume atmospheric CO 2. However, by enhancing the dissolution of non-silicate, Ca-bearing trace minerals, they could contribute to high Ca/Na ratios commonly observed in granitic watersheds.

Nepheline structural and chemical dependence on melt composition

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

Marcial, José; Crum, Jarrod; Neill, Owen

Nepheline crystallizes upon slow-cooling in some melts concentrated in Na2O and Al2O3, which can result in a residual glass phase of low chemical durability. Nepheline can incorporate many components often found in high-level waste radioactive borosilicate glass, including glass network ions (e.g., Si, Al, Fe), alkali metals (e.g., Cs, K, Na, and possibly Li), alkaline-earth metals (e.g., Ba, Sr, Ca, Mg), and transition metals (e.g., Mn, and possibly Cr, Zn, Ni). When crystallized from melts of different compositions, nepheline chemistry varies as a function of starting glass composition. Five simulated high level nuclear waste borosilicate glasses shown to crystallize largemore » fractions of nepheline on slow cooling, were selected for study. These melts constituted a range of Al2O3, B2O3, CaO, Na2O, K2O, Fe2O3, and SiO2 compositions. Compositional analyses of nepheline crystals in glass by electron probe micro-analysis (EPMA) indicate that boron is unlikely to be present in any significant concentration, if at all, in nepheline. Also, several models are presented for calculating the fraction of vacancies in the nepheline structure.« less

[Determination of 22 inorganic elements in different parts of Lantana camara by ICP-OES].

PubMed

Zhou, Wei-ming; Wang, Ru-yi; Chen, Liu-sheng; Huang, Chuan-bin

2014-10-01

To determine the contents of 22 inorganic elements in different parts of Lantana camara by inductively coupled plasma optical emission spectroscopy (ICP-OES). HNO3-H2O2 digested system was used to completely decompose the organic compounds effectually by microwave digestion. The 22 inorganic elements such as K, Ca, Mg, Fe, Al, Na, Zn, Mn and Cr were determined by ICP-OES under set up working conditions. The contents of K, Ca and Mg were the most in different parts of Lantana camara; The contents of K, Ca, Mg, Mn, Sr and Cu in the leaf were more those that in the root and branch; The contents of Fe, Na, Cr and Ni in the root were more than those in the leaf and branch; The contents of Mn, Zn, Sr and Cu in the branch were more than those in the root and the leaf; The contents of Pb and Cd were higher than the national standard and Cr had high content in different parts of Lantana camara. The determination method is quick, easy and accurate with high sensitivity, which can determine the contents of 22 inorganic elements accurately in different parts of Lantana camara.

Pyroxenoids of pyroxmangite-pyroxferroite series from xenoliths of Bellerberg paleovolcano (Eifel, Germany): Chemical variations and specific features of cation distribution

NASA Astrophysics Data System (ADS)

Shchipalkina, N. V.; Aksenov, S. M.; Chukanov, N. V.; Pekov, I. V.; Rastsvetaeva, R. K.; Schäfer, C.; Ternes, B.; Shüller, W.

2016-11-01

The pyroxferroite and pyroxmangite from xenoliths of aluminous gneisses in the alkaline basalts of Bellerberg paleovulcano (Eifel, Germany) have been studied by electron-probe and X-ray diffraction methods and IR spectroscopy. The parameters of the triclinic unit cells are found to be a = 6.662(1) Å, b = 7.525(1) Å, c = 15.895(2) Å, α = 91.548(3)°, β = 96.258(3)°, and γ = 94.498(3)° for pyroxferroite and a = 6.661(3) Å, b = 7.513(3) Å, c = 15.877(7) Å, α = 91.870(7)°, β = 96.369(7)°, and γ = 94.724(7)° for pyroxmangite; sp. gr. Poverline 1 . The crystallochemical formulas ( Z = 2) are, respectively, M(1-2)(Mn0.5Ca0.4Na0.1)2 M(3-6)(Fe, Mn)4 M7[Mg0.6(Fe, Mn)0.4][Si7O21] and M(1-3)(Mn, Fe)3 M(4-6)[(Fe, Mn)0.7Mg0.3]3 M7[Mg0.5(Fe, Mn)0.5][Si7O21]. For these and previously studied representatives of the pyroxmangite structural type, an analysis of the cation distribution over sites indicates wide isomorphism of Mn2+, Fe2+, and Mg in all cation M(1-7) sites and the preferred incorporation of Ca and Na into large seven-vertex M1O7 and M2O7 polyhedra and Mg into the smallest five-vertex M7O5 polyhedron.

Montmorillonite-supported Pd0, Fe0, Cu0 and Ag0 nanoparticles: Properties and affinity towards CO2

NASA Astrophysics Data System (ADS)

Bouazizi, Nabil; Barrimo, Diana; Nousir, Saadia; Ben Slama, Romdhane; Roy, René; Azzouz, Abdelkrim

2017-04-01

This study reports the carbon dioxide (CO2) adsorption on montmorillonite (NaMt) incorporating Cu0, Fe0, Pd0 and Ag0 as metallic nanoparticles (MNPs). The changes in structural, textural, morphological and adsorption properties of the resulting materials (NaMt-MNPs) were investigated. Electron microscopy and X-ray diffraction showed that dispersion of fine MNPs occurs mainly within the interlayer space of NaMt, producing a slight structure expansion. This was accompanied by a visible enhancement of the affinity towards CO2, as supported by thermal programmed desorption measurements. NaMt-MNPs displayed high CO2 retention capacity (CRC) of ca. 657 μmol/g for NaMt-Cu as compared to NaMt. This was explained in terms of increased number of available adsorption sites due to enlarged interlayer spaces caused by MNP insertion. The differences in CO2 adsorption capacities clearly demonstrate the key role of MNPs in improving the surface properties and adsorption capacity. The results reported herein open new prospects for clay supported metal nanoparticles as efficient adsorbents for CO2.

Iron oxides in eroded sediments from two representative catchments form South Spain: an example of its environmental implications

NASA Astrophysics Data System (ADS)

Diaz, I.; del Campillo, M. C.; Barrón, V.; Delgado, A.

2012-04-01

Iron (Fe) oxides accounts for one of the most important sorbent compounds in soil and sediments. Nutrients such as P and organic and inorganic pollutants can be retained in soils through its adsorption on these compounds. Particles of Fe oxides can act as a source of sorbed pollutants when these particles are eroded and transported into the bottom of lakes or water as a result of desorption of sorbed compounds or after reduction of Fe oxides under anaerobic conditions. The main target of this work was to study Fe oxides in sediments eroded from two representative catchments from South Spain and how the content and type of oxides in sediments can be affected by the soil properties. One catchment had an extension of 60 ha and soils were mainly classified as Vertisols, with 44-50 % clay in the upper horizon and pH ranging from 7.4 to 7.9. Soils in the other catchment, with an extension of 25 ha, were mainly Alfisols, with 6-33 % clay in the upper horizon and pH between 7.4 and 8.0. Phosphorus and Fe fractions in soil (18 and 10 sampling points in the Vertisol and Alfisols catchment, respectively) and sediments in runoff samples (taken during two consecutive agricultural years, 2000-2002) were studied by means of a sequential fractionation method involving extraction with: NaOH, citrate-bicarbonate (CB), citrate (C), citrate-ascorbate (CA), citrate-bicarbonate-dithionite (CBD), acetate, and HCl. Iron extraction involved sequential extraction with of CB, C, CA and CBD. The two formers step in the Fe fractionation dissolve the poorly crystalline and crystalline Fe oxides, respectively. The concentrations of all the Fe and P fractions were similar in sediments (sum of fractions were 11.5 g Fe/kg and 509 mg P/kg) and soil (sum of fractions were 10.5 g Fe/kg and 586 mg P/kg) from the Vertisol catchment. In this highly calcareous soil, the relevance of Fe oxides in the dynamics of applied P fertilizer was secondary when compared with the precipitation of poorly soluble Ca phosphates, as revealed by the significance of citrate extractable P. In the Alfisols catchment, however, the total free Fe (sum of fractions) was much higher in the sediments (19 g/kg) than in the soil (7.9 g/kg) which explains the increased amounts of P fractions related to oxides (NaOH, CB, CA, and CBD) in sediments (425 mg/kg) when compared with soils (183 mg/kg). Also, the ratio of CA to CBD extractable Fe was higher in sediments (0.22) than in soils (0.15). It can be concluded that in the Alfisol catchment, the content of sorbent surfaces sensitive to reductant conditions are increased in the sediments eroded when compared with soils, and thus, the potential release of pollutants (in this case P) adsorbed or occluded in them. In contrast, in the Vertisol catchment, where P dynamics is dominated by precipitation of Ca phosphates, these forms accounts for the dominant one in soils and sediments, without an increase in the proportion of sorbent surfaces or P forms sensitive to redox conditions.

The development of magnetic degradable DP-Bioglass for hyperthermia cancer therapy.

PubMed

Wang, Tzu-Wei; Wu, Hsi-Chin; Wang, Wei-Ren; Lin, Feng-Huei; Lou, Pei-Jen; Shieh, Ming-Jium; Young, Tai-Horng

2007-12-01

In this study, a novel magnetic degradable material was developed by adding Fe ions into DP-Bioglass (Na(2)O-CaO-P(2)O(5)-SiO(2)) as thermoseed for hyperthermia cancer therapy under an alternating magnetic field. We have investigated the properties of developed magnetic DP-Bioglass including morphology, chemical composition, and magnetism. The degradability was conducted by measuring the released concentrations of Na, Ca, Si, P, and Fe ions. The biocompatibility was analyzed by biological assays, and the functional hyperthermia effect to cancer cells was evaluated by in vitro cell culture test. In the results, the morphology of synthesized magnetic DP-Bioglass was revealed in sphere and rod shape with particle size around 50-100 nm. From the hysteresis loop analysis, it showed that the group of Fe/Bioglass = 0.2 possessed the maximum magnetization property. When cultured with fibroblasts, the magnetic DP-Bioglass had no significant influence on cell viability and mediated low cytotoxicity. The thermal-induced property demonstrated that after exposure to an alternating magnetic field, the cell number of human Caucasian lung carcinoma cells (A549) was significantly decreased when temperature was increasing to 45 degrees C. In brief, successfully incorporated with Fe ions by sol-gel method, this magnetic degradable DP-Bioglass possessed the potential and properties of hyperthermia effect to lung carcinoma cells. Copyright 2007 Wiley Periodicals, Inc.

The effect of iron content and dissolved O2 on dissolution rates of clinopyroxene at pH 5.8 and 25°C: Preliminary results

USGS Publications Warehouse

Hoch, A.R.; Reddy, M.M.; Drever, J.I.

1996-01-01

Dissolution experiments using augite (Mg0.87Ca0.85Fe0.19Na0.09Al0.03Si2O6) and diopside (Mg0.91Ca0.93Fe0.07Na0.03Al0.03Si2O6) were conducted in flow-through reactors (5-ml/h flow rate). A pH of 5.8 was maintained by bubbling pure CO2 through a solution of 0.01 M KHCO3 at 25°C. Two experiments were run for each pyroxene type. In one experiment dissolved O2 concentration in reactors was 0.6 (±0.1) ppm and in the second dissolved O2 was 1.5 (±0.1) ppm. After 60 days, augite dissolution rates (based on Si release) were approximately three times greater in the 1.5 ppm. dissolved O2 experiments than in the sealed experiments. In contrast, diopside dissolution rates were independent of dissolved O2 concentrations. Preliminary results from the augite experiments suggest that dissolution rate is directly related to oxidation of iron. This effect was not observed in experiments performed on iron-poor diopside. Additionally, dissolution rates of diopside were much slower than those of augite, again suggesting a relationship between Fe content, Fe oxidation and dissolution rates.

Phase equilibria in the NaF-CdO-NaPO3 system at 873 K and crystal structure and physico-chemical characterizations of the new Na2CdPO4F fluorophosphate

NASA Astrophysics Data System (ADS)

Aboussatar, Mohamed; Mbarek, Aïcha; Naili, Houcine; El-Ghozzi, Malika; Chadeyron, Geneviève; Avignant, Daniel; Zambon, Daniel

2017-04-01

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO3 system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO4 side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na2CdPO4F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1), c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na2CaPO4F and the fluorosilicate Ca2NaSiO4F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na2MIIPO4F (MII=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and 19F, 23Na, 31P MAS NMR characterizations of Na2CdPO4F have been investigated.

On the understanding and control of the spontaneous heating of dried tannery wastewater sludge.

PubMed

Biasin, A; Della Zassa, M; Zerlottin, M; Refosco, D; Bertani, R; Canu, P

2014-04-01

We studied the spontaneous heating of dried sludge produced by treating wastewater mainly originating from tanneries. Heating up to burning has been observed in the presence of air and moisture, starting at ambient temperature. To understand and prevent the process we combined chemical and morphological analyses (ESEM) with thermal activity monitoring in insulated vessels. Selective additions of chemicals, either to amplify or depress the reactivity, have been used to investigate and identify both the chemical mechanism causing the sludge self-heating, and a prevention or a mitigation strategy. FeS additions accelerate the onset of reactivity, while S sustains it over time. On the contrary, Ca(OH)2, Na2CO3, NaHCO3, FeCl2, EDTA, NaClO can limit, up to completely preventing, the exothermic activity. All the experimental evidences show that the reactions supporting the dried sludge self-heating involve the Fe/S/O system. The total suppression of the reactivity requires amounts of additives that are industrially incompatible with waste reduction and economics. The best prevention requires reduction or removal of S and Fe from the dried solid matrix. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient degradation of TCE in groundwater using Pd and electro-generated H2 and O2: a shift in pathway from hydrodechlorination to oxidation in the presence of ferrous ions.

PubMed

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N

2012-03-20

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H(2) and O(2) is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H(2)O(2) up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radicals are detected due to decomposition of H(2)O(2), slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na(2)SO(4), NaCl, NaNO(3), NaHCO(3), K(2)SO(4), CaSO(4), and MgSO(4) does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppress degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation.

Efficient Degradation of TCE in Groundwater Using Pd and Electro-generated H2 and O2: A Shift in Pathway from Hydrodechlorination to Oxidation in the Presence of Ferrous Ions

PubMed Central

Yuan, Songhu; Mao, Xuhui; Alshawabkeh, Akram N.

2012-01-01

Degradation of trichloroethylene (TCE) in simulated groundwater by Pd and electro-generated H2 and O2 is investigated in the absence and presence of Fe(II). In the absence of Fe(II), hydrodechlorination dominates TCE degradation, with accumulation of H2O2 up to 17 mg/L. Under weak acidity, low concentrations of oxidizing •OH radical are detected due to decomposition of H2O2, slightly contributing to TCE degradation via oxidation. In the presence of Fe(II), the degradation efficiency of TCE at 396 μM improves to 94.9% within 80 min. The product distribution proves that the degradation pathway shifts from 79% hydrodechlorination in the absence of Fe(II) to 84% •OH oxidation in the presence of Fe(II). TCE degradation follows zeroth-order kinetics with rate constants increasing from 2.0 to 4.6 μM/min with increasing initial Fe(II) concentration from 0 to 27.3 mg/L at pH 4. A good correlation between TCE degradation rate constants and •OH generation rate constants confirms that •OH is the predominant reactive species for TCE oxidation. Presence of 10 mM Na2SO4, NaCl, NaNO3, NaHCO3, K2SO4, CaSO4 and MgSO4 does not significantly influence degradation, but sulfite and sulfide greatly enhance and slightly suppresses degradation, respectively. A novel Pd-based electrochemical process is proposed for groundwater remediation. PMID:22315993

Chemical profile of size-fractionated soils collected in a semiarid industrial area of Argentina

NASA Astrophysics Data System (ADS)

Morales Del Mastro, Anabella; Pereyra, Marcelo; Londonio, Agustín; Pereyra, Victoria; Rebagliati, Raúl Jiménez; Dawidowski, Laura; Gómez, Darío; Smichowski, Patricia

2014-12-01

A study was undertaken to assess the chemical profile of soil collected in Bahía Blanca (Argentina). In this industrial city, semiarid soils are affected by different industrial and agricultural activities, the presence of a saltpeter extraction facility, traffic and increasing urbanization. Sixteen soil samples (superficial and sub-superficial) were collected. Samples were sieved in two fractions (A < 37 μm, and 37 < B < 50 μm) before elemental analysis. Major, minor and trace elements namely, Al, As, Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Ti, V and Zn were determined by inductively coupled plasma optical emission spectrometry (ICP OES). Anions (Cl-, F-, SO42-) and cations (K+, Na+ and NH4+) were determined by high performance liquid chromatography (HPLC) after an aqueous extraction. As expected, crustal elements namely, Al, Ca, Fe, Mg and Ti exhibited the highest concentrations. Mean elemental concentration ranged from <0.3 μg g-1 (Sb) to 14.6 ± 0.6% (Ca). Ions concentrations in the soluble fraction measured at mg g-1 levels were in the order Cl- > Na+ ≅ SO42- > K+ > NO3-. Three indicators, namely, (i) coefficient of variation, (ii) coefficient of divergence and (iii) ratio of elemental concentration with respect to Ca were used to assess chemical, spatial and inter-profile variability. Chloride > Ca > Na+ > Mo > SO42-, dominated the variability indicating that these are key chemical markers for future assessment of crustal contribution to airborne particles in the area. The ratios Xi/Ca allowed discriminating the soil of the semi-arid region surrounding Bahía Blanca. The chemical profiles obtained in this study, particularly those of topsoil, will be a key input to characterize soil resuspension and its contribution to airborne particulate matter in a forthcoming receptor model analysis.

Quantum-chemical modeling of smectite clays

NASA Technical Reports Server (NTRS)

Aronowitz, S.; Coyne, L.; Lawless, J.; Rishpon, J.

1982-01-01

A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors.

Metals geochemistry and mass export from the Mississippi-Atchafalaya River system to the Northern Gulf of Mexico.

PubMed

Reiman, Jeremy H; Xu, Y Jun; He, Songjie; DelDuco, Emily M

2018-08-01

Discharging 680 km 3 of freshwater annually to the Northern Gulf of Mexico (NGOM), the Mississippi-Atchafalaya River System (MARS) plays a significant role in transporting major and trace elements to the ocean. In this study, we analyzed total recoverable concentrations of thirty-one metals from water samples collected at five locations along the MARS during 2013-2016 to quantify their seasonal mass exports. The Atchafalaya River flows through a large swamp floodplain, allowing us to also test the hypothesis that floodplains function as a sink for metals. We found that the seven major elements (Ca, Na, Mg, Si, K, Al, and Fe) constituted 99% of the total annual mass load of metals (7.38 × 10 7 tons) from the MARS. Higher concentrations of Al, Ba, B, Ca, Fe, Mg, Mn, Ag, and Ti were found in the Mississippi River, while significantly higher Si and Na concentrations were found in the Atchafalaya River. Significant relationships were found between daily discharge and daily loads of Ba, Ca, Fe, K, Sr, and Ti in both rivers, while significant relationships were also found for Al, Mg, Mn, V, and Zn in the Atchafalaya River and B in the Mississippi River. Overall, the Mississippi River contributed 64-76% of the total annual loading of metals from the MARS to the NGOM. Daily loads of Al, Ba, B, Fe, Li, Mn, P, K, Si, Ag, Ti, V, and Zn regularly decreased upstream to downstream in the Atchafalaya River, partially accepting the initial hypothesis on metals transport in river floodplains. Copyright © 2018 Elsevier Ltd. All rights reserved.

Magnesium Chemistry in the Upper Atmosphere

DTIC Science & Technology

2010-12-20

17,20 Unlike the other prominent meteoric metals (Fe, Na, K and Ca), neither Mg nor Mg+ can be observed by ground-based lidar (laser radar ) as...with a 1200 groove mm-1 grating (resolution 0.12 nm FWHM). Absorption spectra were recorded with a photodiode array (EG&G, PARC 1412) and converted

Metal analysis of cotton

USDA-ARS?s Scientific Manuscript database

Seven varieties of cotton were investigated for 8 metal ions (K, Na, Mg, Ca, Fe, Cu, Zn, and Mn) using Inductively Coupled Plasma-Optical Emission Spectroscopy. All of the varieties were grown at the same location. Half of the samples were dry (rain fed only) and the other were well-watered (irrigat...

Volatilization, transport and sublimation of metallic and non-metallic elements in high temperature gases at Merapi Volcano, Indonesia

USGS Publications Warehouse

Symonds, R.B.; Rose, William I.; Reed, M.H.; Lichte, F.E.; Finnegan, David L.

1987-01-01

Condensates, silica tube sublimates and incrustations were sampled from 500-800??C fumaroles and lava samples were collected at Merapi Volcano, Indonesia in Jan.-Feb., 1984. With respect to the magma, Merapi gases are enriched by factors greater than 105 in Se, Re, Bi and Cd; 104-105 in Au, Br, In, Pb and W; 103-104 in Mo, Cl, Cs, S, Sn and Ag; 102-103 in As, Zn, F and Rb; and 1-102 in Cu, K, Na, Sb, Ni, Ga, V, Fe, Mn and Li. The fumaroles are transporting more than 106 grams/day ( g d) of S, Cl and F; 104-106 g/d of Al, Br, Zn, Fe, K and Mg; 103-104 g d of Pb, As, Mo, Mn, V, W and Sr; and less than 103 g d of Ni, Cu, Cr, Ga, Sb, Bi, Cd, Li, Co and U. With decreasing temperature (800-500??C) there were five sublimate zones found in silica tubes: 1) cristobalite and magnetite (first deposition of Si, Fe and Al); 2) K-Ca sulfate, acmite, halite, sylvite and pyrite (maximum deposition of Cl, Na, K, Si, S, Fe, Mo, Br, Al, Rb, Cs, Mn, W, P, Ca, Re, Ag, Au and Co); 3) aphthitalite (K-Na sulfate), sphalerite, galena and Cs-K. sulfate (maximum deposition of Zn, Bi, Cd, Se and In; higher deposition of Pb and Sn); 4) Pb-K chloride and Na-K-Fe sulfate (maximum deposition of Pb, Sn and Cu); and 5) Zn, Cu and K-Pb sulfates (maximum deposition of Pb, Sn, Ti, As and Sb). The incrustations surrounding the fumaroles are also chemically zoned. Bi, Cd, Pb, W, Mo, Zn, Cu, K, Na, V, Fe and Mn are concentrated most in or very close to the vent as expected with cooling, atmospheric contamination and dispersion. The highly volatile elements Br, Cl, As and Sb are transported primarily away from high temperature vents. Ba, Si, P, Al, Ca and Cr are derived from wall rock reactions. Incomplete degassing of shallow magma at 915??C is the origin of most of the elements in the Merapi volcanic gas, although it is partly contaminated by particles or wall rock reactions. The metals are transported predominantly as chloride species. As the gas cools in the fumarolic environment, it becomes saturated with sublimate phases that fractionate from the gas in the order of their equilibrium saturation temperatures. Devolatilization of a cooling batholith could transport enough acids and metals to a hydrothermal system to play a significant role in forming an ore deposit. However, sublimation from a high temperature, high velocity carrier gas is not efficient enough to form a large ore deposit. Re, Se, Cd and Bi could be used as supporting evidence for magmatic fluid transport in an ore deposit. ?? 1987.

Orosensory Responsiveness to and Preference for Hydroxide-Containing Salts in Mice

PubMed Central

St. John, Steven J.; Boughter, John D.

2009-01-01

Historically, taste researchers have considered the possibility that the gustatory system detects basic compounds, such as those containing the hydroxide ion, but evidence for an “alkaline taste” has not been strong. We found that, in 48 h, 2-bottle preference tests, C3HeB/FeJ (C3) mice showed a preference for Ca(OH)2, whereas SWR/J (SW) mice showed avoidance. Strain differences were also apparent to NaOH but not CaCl2. Follow-up studies showed that the strain difference for Ca(OH)2 was stable over time (Experiment 2) but that C3 and SW mice did not differ in their responses to Ca(OH)2 or NaOH in brief-access tests, where both mice avoided high concentrations of these compounds (Experiment 3). In order to assess the perceived quality of Ca(OH)2, mice were tested in 2 taste aversion generalization experiments (Experiments 4 and 5). Aversions to Ca(OH)2 generalized to NaOH but not CaCl2 in both strains, suggesting that the generalization was based on the hydroxide ion. Both strains also generalized aversions to quinine, suggesting the possibility that the hydroxide ion has a bitter taste quality to these mice, despite the preference shown by C3 mice to middle concentrations in long-term tests. PMID:19423656

Demonstration of Regenerable, Large-Scale Ion Exchange System Using WBA Resin in Rialto, CA (Drinking Water Treatment - Pilot Scale)

DTIC Science & Technology

2008-08-01

Administration NDBA N-nitrosodi-n-butylamine NDEA N-nitrosodiethylamine NDMA N-nitrosodimethylamine NDPA N-nitrosodi-n-propylamine v ACRONYMS...spectrometry (IC-MS/MS). Nitrosamines were analyzed using EPA Method 521. N-nitrosodimethylamine ( NDMA ) was 2.6 parts per trillion (ppt) with a detection...and metals (Ca, Cu, Fe, Mg, Mn, K, Na , and Zn). Specific methods are listed in Table 5. ** N-nitrosodimethylamine ( NDMA ), N-nitrosodiethylamine

Evaluation of potential human health risk and investigation of drinking water quality in Isparta city center (Turkey).

PubMed

Varol, Simge; Davraz, Aysen

2016-06-01

Isparta city center is selected as a work area in this study because the public believes that the tap water is dirty and harmful. In this study, the city's drinking water in the distribution system and other spring waters which are used as drinking water in this region were investigated from the point of water quality and health risk assessment. Water samples were collected from major drinking water springs, tap waters, treatment plants and dam pond in the Isparta province center. Ca-Mg-HCO3, Mg-Ca-HCO3, Ca-Na-HCO3, Ca-HCO3, Ca-HCO3-SO4 and Ca-Mg-HCO3-SO4 are dominant water types. When compared to drinking water guidelines established by World Health Organization and Turkey, much greater attention should be paid to As, Br, Fe, F, NH4, PO4 through varied chemicals above the critical values. The increases of As, Fe, F, NH4 and PO4 are related to water-rock interaction. In tap waters, the increases of As and Fe are due to corrosion of pipes in drinking water distribution systems. The major toxic and carcinogenic chemicals within drinking water are As and Br for both tap water and spring water. Also, F is the non-carcinogenic chemical for only spring waters in the study area.

Inorganic profile of some Brazilian medicinal plants obtained from ethanolic extract and ''in natura'' samples

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

Ferreira, M.O.M.; de Sousa, P.T.; Salvador, V.L.R.

The Anadenathera macrocarpa, Schinus molle, Hymenaea courbaril, Cariniana legalis, Solidago microglossa and Stryphnodendron barbatiman, were collected ''in natura'' samples (leaves, flowers, barks and seeds) from different commercial suppliers. The pharmaco-active compounds in ethanolic extracts had been made by the Mato Grosso Federal University (UFMT). The energy-dispersive x-ray fluorescence (ED-XRF) spectrometry was used for the elemental analysis in different parts of the plants and respective ethanolic extracts. The Ca, Cl, Cu, Fe, K, Mg, Mn, Na, Ni, P, Rb, S, Sr and Zn concentrations were determined by the fundamental parameters method. Some specimens showed a similar inorganic profile for ''in natura''more » and ethanolic extract samples and some ones showed a distinct inorganic profile. For example, the Anadenathera macrocarpa showed a similar concentration in Mg, P, Cu, Zn and Rb elements in ''in natura'' and ethanolic extract samples; however very different concentration in Na, S, Cl, K , Ca, Mn, Fe and Sr was observed in distinctive samples. The Solidago microglossa showed the K, Ca, Cl, S, Mg, P and Fe elements as major constituents in both samples, suggesting that the extraction process did not affect in a considerable way the ''in natura'' inorganic composition. The elemental composition of the different parts of the plants (leaves, flowers, barks and seeds) has been also determined. For example, the Schinus molle specimen showed P, K, Cl and Ca elements as major constituents in the seeds, Mg, K and Sr in the barks and Mg, S, Cl and Mn in the leaves, demonstrating a differentiated elementary distribution. These inorganic profiles will contribute to evaluate the quality control of the Brazilian herbaceous trade and also will assist to identify which parts of the medicinal plants has greater therapeutic effect.« less

Sampling and major element chemistry of the recent (A.D. 1631-1944) Vesuvius activity

USGS Publications Warehouse

Belkin, H.E.; Kilburn, C.R.J.; de Vivo, B.

1993-01-01

Detailed sampling of the Vesuvius lavas erupted in the period A.D. 1631-1944 provides a suite of samples for comprehensive chemical analyses and related studies. Major elements (Si, Ti, Al, Fetotal, Mn, Mg, Ca, Na, K and P), volatile species (Cl, F, S, H2O+, H2O- and CO2), and ferrous iron (Fe2+) were determined for one hundred and forty-nine lavas and five tephra from the A.D. 1631-1944 Vesuvius activity. The lavas represent a relatively homogeneous suite with respect to SiO2, TiO2, FeOtotal, MnO and P2O5, but show systematic variations among MgO, K2O, Na2O, Al2O3 and CaO. The average SiO2 content is 48.0 wt.% and the rocks are classified as tephriphonolites according to their content of alkalis. All of the lavas are silica-undersaturated and are nepheline, leucite, and olivine normative. There is no systematic variation in major-element composition with time, over the period A.D. 1631-1944. The inter-eruption and intra-eruption compositional differences are the same magnitude. The lavas are highly porphyritic with clinopyroxene and leucite as the major phases. Fractionation effects are not reflected in the silica content of the lavas. The variability of MgO, K2O, Na2O, and CaO can be modelled as a relative depletion or accumulation of clinopyroxene. ?? 1993.

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

Reuse potential of laundry greywater for irrigation based on growth, water and nutrient use of tomato

NASA Astrophysics Data System (ADS)

Misra, R. K.; Patel, J. H.; Baxi, V. R.

2010-05-01

SummaryGreywater is considered as a valuable resource with a high reuse potential for irrigation of household lawns and gardens. However, there are possibilities of surfactant and sodium accumulation in soil from reuse of greywater which may affect agricultural productivity and environmental sustainability adversely. We conducted a glasshouse experiment to examine variation in growth, water and nutrient use of tomato ( Lycopersicon esculentum Mill. cv. Grosse Lisse) using tap water (TW), laundry greywater (GW) and solutions of low and high concentration of a detergent surfactant (LC and HC, respectively) as irrigation treatments. Each treatment was replicated five times using a randomised block design. Measurements throughout the experiment showed greywater to be significantly more alkaline and saline than the other types of irrigation water. Although all plants received 16 irrigations over a period of 9 weeks until flowering, there were little or no significant effects of irrigation treatments on plant growth. Soil water retention following irrigation reduced significantly when plants were irrigated with GW or surfactant solutions on only three of 12 occasions. On one occasion, water use measured as evapotranspiration (ET) with GW irrigation was similar to TW, but it was significantly higher than the plants receiving HC irrigation. At harvest, various components of plant biomass and leaf area for GW irrigated plants were found to be similar or significantly higher than the TW irrigated plants with a common trend of GW ⩾ TW > LC ⩾ HC. Whole-plant concentration was measured for 12 essential plant nutrients (N, P, K, Ca, Mg, S, Fe, Cu, Mn, Zn, Mo and B) and Na (often considered as a beneficial nutrient). Irrigation treatments affected the concentration of four nutrients (P, Fe, Zn and Na) and uptake of seven nutrients (P, K, Ca, Mg, Na, Fe and B) significantly. Uptake of these seven nutrients by tomato was generally in the order GW ⩾ TW > HC ⩾ LC. GW irrigated plants had the highest concentration of P, Na and Fe which were 39-85% higher than the TW irrigated plants. Compared with tap water irrigated plants, greywater irrigated plants removed only 6% excess B, but substantially greater quantity of Na (83%) and Fe (86%). These results suggest that laundry greywater has a promising potential for reuse as irrigation water to grow tomato.

The effect of bulk composition on the solidus of carbonated eclogite from partial melting experiments at 3 GPa

NASA Astrophysics Data System (ADS)

Dasgupta, Rajdeep; Hirschmann, Marc M.; Dellas, Nikki

2005-05-01

To explore the effect of bulk composition on the solidus of carbonated eclogite, we determined near-solidus phase relations at 3 GPa for four different nominally anhydrous, carbonated eclogites. Starting materials (SLEC1, SLEC2, SLEC3, and SLEC4) were prepared by adding variable proportions and compositions of carbonate to a natural eclogite xenolith (66039B) from Salt Lake crater, Hawaii. Near-solidus partial melts for all bulk compositions are Fe Na calcio-dolomitic and coexist with garnet + clinopyroxene + ilmenite ± calcio-dolomitic solid solution. The solidus for SLEC1 (Ca#=100 × molar Ca/(Ca + Mg + FeT)=32, 1.63 wt% Na2O, and 5 wt% CO2) is bracketed between 1,050°C and 1,075°C (Dasgupta et al. in Earth Planet Sci Lett 227:73 85, 2004), whereas initial melting for SLEC3 (Ca# 41, 1.4 wt% Na2O, and 4.4 wt% CO2) is between 1,175°C and 1,200°C. The solidus for SLEC2 (Ca# 33, 1.75 wt% Na2O, and 15 wt% CO2) is estimated to be near 1,100°C and the solidus for SLEC3 (Ca# 37, 1.47 wt% Na2O, and 2.2 wt% CO2) is between 1,100°C and 1,125°C. Solidus temperatures increase with increasing Ca# of the bulk, owing to the strong influence of the calcite magnesite binary solidus-minimum on the solidus of carbonate bearing eclogite. Bulk compositions that produce near-solidus crystalline carbonate closer in composition to the minimum along the CaCO3-MgCO3 join have lower solidus temperatures. Variations in total CO2 have significant effect on the solidus if CO2 is added as CaCO3, but not if CO2 is added as a complex mixture that maintains the cationic ratios of the bulk-rock. Thus, as partial melting experiments necessarily have more CO2 than that likely to be found in natural carbonated eclogites, care must be taken to assure that the compositional shifts associated with excess CO2 do not unduly influence melting behavior. Near-solidus dolomite and calcite solid solutions have higher Ca/(Ca + Mg) than bulk eclogite compositions, owing to Ca Mg exchange equilibrium between carbonates and silicates. Carbonates in natural mantle eclogite, which have low bulk CO2 concentration, will have Ca/Mg buffered by reactions with silicates. Consequently, experiments with high bulk CO2 may not mimic natural carbonated eclogite phase equilibria unless care is taken to ensure that CO2 enrichment does not result in inappropriate equilibrium carbonate compositions. Compositions of eclogite-derived carbonate melt span the range of natural carbonatites from oceanic and continental settings. Ca#s of carbonatitic partial melts of eclogite vary significantly and overlap those of partial melts of carbonated lherzolite, however, for a constant Ca-content, Mg# of carbonatites derived from eclogitic sources are likely to be lower than the Mg# of those generated from peridotite.

Presumed Multiple Metasomatism underneath the Colorado Plateau; Decoding from Chemistry and Inclusion/Lamella Mineralogy of Diverse Garnets from the Garnet Ridge, Northern Arizona

NASA Astrophysics Data System (ADS)

Sato, Y.; Ogasawara, Y.

2015-12-01

Various garnets containing the information on mantle petrology and related metasomatism occur at the Garnet Ridge, Colorado Plateau. The origins of garnets range from deep mantle to shallow continental crust. These garnets were delivered by kimberlitic diatreme of 30 Ma (Smith et al. 2004). We have classified the garnets into 10 groups (A to J, see figure) by naked eye observation, major chemistry, minor Na-Ti-P, inclusion/lamella mineralogy. Among them, groups A to D are of mantle origin, E to G of subducted oceanic crust origin, and H to J of continental crust origin. We summarized results as in the followings. A: Cr and pyrope-rich garnet has Cr2O3(0.8-6.3 wt.%) and inclusions of Ol, Cpx, Opx, Ti-Chu/Chn and carbonates, indicating carbonated garnet lherzolites as host. Cr contents negatively correlates with Na-Ti-P contents and occurrence of exsolved Rt, Ilm and crichtonite. This indicates Cr-rich end-member is the most "primitive" mantle garnet before metasomatism. B: Pyrope-rich reddish brown garnet of peridotitic origins was subdivided into 4 subgroups (B1 to B4, see figure). Compositional range in Ca-Mg-Fe triangle expands to Fe-rich side from group A. Exsolved Na-bearing amphibole and inclusions of Ap, carbonates and fluid were identified. These indicate metasomatism of group A. C: Garnet megacryst is coarse-grained garnet (2-10 cm across) with crystal faces. This garnet has wide chemical variation plotted in the center area of Ca-Mg-Fe triangle. D: Garnet aggregate has similar chemistry of group C and is composed of several grains. Grain boundaries of garnet were recognized by Rt, Ilm and other minerals and oscillatory zonings of Ca, Mg, Fe and Na-Ti-P. Fluid inclusions of groups C and D suggest these garnets might crystalized from fluid. E: Garnet in eclogite and F: Garnet in metasomatized eclogite are xenolith samples (the Fallaron Plate origin?). Aggregate of Zo+Ab contained in group E indicates decomposed precursor lawsonite inclusion. G: Quartz lamella-bearing garnet (relatively high Na2O: 0.03-0.06 wt.%) contains inclusions of Omp and Zrn and oriented lamellae of Qtz, Rt and Ap. These suggest eclogitic origins deeper than groups E and F. Above features in garnets from the Garnet Ridge constrain their formations by multistage and wide range intensity of metasomatisms underneath the Colorado Plateau.

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

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

Ferencz, Zs.; Szabados, M.; Varga, G.

2016-01-15

A mechanochemical method (grinding the components without added water – dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution – wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure wasmore » also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic–inorganic nanocomposites: LDHs intercalated with amino acid anions. - Graphical abstract: Amino acid anion-Ca(II)Fe(III)-LDHs were successfully prepared by a two-step milling procedure. - Highlights: • Synthesis of pristine and amino acid intercalated CaFe-LDHs by two-step milling. • Identifying the optimum synthesis and intercalation parameters. • Characterisation of the samples with a range of instrumental methods.« less

Elemental and carbonaceous characterization of TSP and PM10 during Middle Eastern dust (MED) storms in Ahvaz, Southwestern Iran.

PubMed

Shahsavani, Abbas; Yarahmadi, Maryam; Hadei, Mostafa; Sowlat, Mohammad Hossein; Naddafi, Kazem

2017-08-21

Middle Eastern dust (MED) storms carry large amounts of dust particles to the Southern and Western cities of Iran. This study aimed to characterize the elemental and carbonaceous composition of total suspended particles (TSP) and PM 10 in Ahvaz, Iran. TSP and PM 10 samples were collected using two separate high-volume air samplers. The sampling program was performed according to EPA guidelines and resulted in 72 samples. Twenty-eight elements and two carbonaceous components in TSP and PM 10 were measured. Over the entire study period, the mean concentration (SD) of TSP and PM 10 was 1548.72 μg/m 3 (1965.11 μg/m 3 ) and 1152.35 μg/m 3 (1510.34 μg/m 3 ), respectively. The order of concentrations of major species were Si > Al > Ca > OC > Na > B > Zn > Mn > K > Mg and Si > Ca > Al > Na > OC > B > K > Mn > Cu > Mg for TSP and PM 10 , respectively. Almost all elements (except for Cd, Cr, and Cu) and carbonaceous components (except for organic carbon) had dust days/non-dust days (DD/NDD) ratios higher than 1, implying that all components are somehow affected by dust storms. Crustal elements constituted the major portion of particles for both TSP and PM 10 in both DDs and NDDs. The enrichment factor of elements such as Ca, Fe, K, Mg, Na, and Ti was near unity. Species such as Al, Ca, Fe, K, Na, Si, and EC had high correlation coefficients in both TSP and PM 10 (except for EC). In conclusion, Ahvaz is exposed to high concentrations of TSP and PM 10 during the MED period. Immediate actions must be planned to decrease the high concentrations of particulate matter in Ahvaz's ambient air.

On the entropy of glaucophane Na2Mg3Al2Si8O22(OH)2

USGS Publications Warehouse

Robie, R.A.; Hemingway, B.S.; Gillet, P.; Reynard, B.

1991-01-01

The heat capacity of glaucophane from the Sesia-Lanza region of Italy having the approximate composition (Na1.93Ca0.05Fe0.02) (Mg2.60Fe0.41) (Al1.83Fe0.15Cr0.01) (Si7.92Al0.08)O22(OH)2 was measured by adiabatic calorimetry between 4.6 and 359.4 K. After correcting the Cp0data to values for ideal glaucophane, Na2Mg3Al2Si8O22(OH)2 the third-law entropy S2980-S00was calculated to be 541.2??3.0 J??mol-1??K-1. Our value for S2980-S00is 12.0 J??mol-1??K-1 (2.2%) smaller than the value of Likhoydov et al. (1982), 553.2??3.0, is within 6.2 J??mol-1??K-1 of the value estimated by Holland (1988), and agrees remarkably well with the value calculated by Gillet et al. (1989) from spectroscopic data, 539 J??mol-1??K-1. ?? 1991 Springer-Verlag.

Multivariate analysis of selected metals in tannery effluents and related soil.

PubMed

Tariq, Saadia R; Shah, Munir H; Shaheen, N; Khalique, A; Manzoor, S; Jaffar, M

2005-06-30

Effluent and relevant soil samples from 38 tanning units housed in Kasur, Pakistan, were obtained for metal analysis by flame atomic absorption spectrophotometric method. The levels of 12 metals, Na, Ca, K, Mg, Fe, Mn, Cr, Co, Cd, Ni, Pb and Zn were determined in the two media. The data were evaluated towards metal distribution and metal-to-metal correlations. The study evidenced enhanced levels of Cr (391, 16.7 mg/L) and Na (25,519, 9369 mg/L) in tannery effluents and relevant soil samples, respectively. The effluent versus soil trace metal content relationship confirmed that the effluent Cr was strongly correlated with soil Cr. For metal source identification the techniques of principal component analysis, and cluster analysis were applied. The principal component analysis yielded two factors for effluents: factor 1 (49.6% variance) showed significant loading for Ca, Fe, Mn, Cr, Cd, Ni, Pb and Zn, referring to a tanning related source for these metals, and factor 2 (12.6% variance) with higher loadings of Na, K, Mg and Co, was associated with the processes during the skin/hide treatment. Similarly, two factors with a cumulative variance of 34.8% were obtained for soil samples: factor 1 manifested the contribution from Mg, Mn, Co, Cd, Ni and Pb, which though soil-based is basically effluent-derived, while factor 2 was found associated with Na, K, Ca, Cr and Zn which referred to a tannery-based source. The dendograms obtained from cluster analysis, also support the observed results. The study exhibits a gross pollution of soils with Cr at levels far exceeding the stipulated safe limit laid down for tannery effluents.

Disparities of Selected Metal Levels in the Blood and Scalp Hair of Ischemia Heart Disease Patients and Healthy Subjects.

PubMed

Ilyas, Asim; Shah, Munir H

2017-12-01

Imbalances in the concentrations of trace metals have become an increasingly recognized source of infirmity worldwide particularly in the development of ischemia heart disease (IHD). Present study is intended to analyze the concentrations of Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Pb, Sr, and Zn in the blood and scalp hair of the patients and counterpart controls by flame atomic absorption spectrometry after wet-acid digestion. On the average, Cd, Co, Cr, Fe, K, Li, Mn, Na, and Pb revealed significantly elevated concentrations in the blood of the patients compared with the controls (p < 0.05), whereas mean levels of Ca, Cd, Fe, K, Li, Pb, and Sr in the scalp hair were significantly higher in the patients than the controls (p < 0.05). Most of the metals exhibited noticeable disparities in their concentrations based on gender, abode, dietary/smoking habits, and occupations of both donor groups. The correlation study and multivariate statistical analyses revealed some significantly divergent associations and apportionment of the metals in both donor groups. Overall, comparative variations of the metal contents in blood/scalp hair of the patients were significantly different than the controls; thus, evaluation of trace metals status may be indicative of pathological disorders, such as IHD.

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.

Effects of chemical elements in the trophic levels of natural salt marshes.

PubMed

Kamiński, Piotr; Barczak, Tadeusz; Bennewicz, Janina; Jerzak, Leszek; Bogdzińska, Maria; Aleksandrowicz, Oleg; Koim-Puchowska, Beata; Szady-Grad, Małgorzata; Klawe, Jacek J; Woźniak, Alina

2016-06-01

The relationships between the bioaccumulation of Na, K, Ca, Mg, Fe, Zn, Cu, Mn, Co, Cd, and Pb, acidity (pH), salinity (Ec), and organic matter content within trophic levels (water-soil-plants-invertebrates) were studied in saline environments in Poland. Environments included sodium manufactures, wastes utilization areas, dumping grounds, and agriculture cultivation, where disturbed Ca, Mg, and Fe exist and the impact of Cd and Pb is high. We found Zn, Cu, Mn, Co, and Cd accumulation in the leaves of plants and in invertebrates. Our aim was to determine the selectivity exhibited by soil for nutrients and heavy metals and to estimate whether it is important in elucidating how these metals are available for plant/animal uptake in addition to their mobility and stability within soils. We examined four ecological plant groups: trees, shrubs, minor green plants, and water macrophytes. Among invertebrates, we sampled breastplates Malacostraca, small arachnids Arachnida, diplopods Diplopoda, small insects Insecta, and snails Gastropoda. A higher level of chemical elements was found in saline polluted areas (sodium manufactures and anthropogenic sites). Soil acidity and salinity determined the bioaccumulation of free radicals in the trophic levels measured. A pH decrease caused Zn and Cd to increase in sodium manufactures and an increase in Ca, Zn, Cu, Cd, and Pb in the anthropogenic sites. pH increase also caused Na, Mg, and Fe to increase in sodium manufactures and an increase in Na, Fe, Mn, and Co in the anthropogenic sites. There was a significant correlation between these chemical elements and Ec in soils. We found significant relationships between pH and Ec, which were positive in saline areas of sodium manufactures and negative in the anthropogenic and control sites. These dependencies testify that the measurement of the selectivity of cations and their fluctuation in soils provide essential information on the affinity and binding strength in these environments. The chemical elements accumulated in soils and plants; however, further flow is selective and variable. The selectivity exhibited by soil systems for nutrients and heavy metals is important in elucidating how these metals become available for plant/animal uptake and also their mobility and stability in soils.

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.

Formation of Fe nanoparticles on water-washed coal fly ash for enhanced reduction of p-nitrophenol.

PubMed

Park, Jaehyeong; Bae, Sungjun

2018-07-01

The catalytic reduction of p-nitrophenol (p-NP) by coal fly ash (FA) washed with water was investigated in this study. A significant increase in pH (from 7.0 to 10.1) was observed in the suspension of raw fly ash (RFA), while water-washed fly ash (WFA) showed a relatively lower increase in pH (7.2), which was caused by the dissolution of Ca species during the water-washing process. Almost 33.4% of p-NP reduction was observed in the RFA suspension with NaBH 4 in 1 h, while the enhanced reduction of p-NP (87.2%) was observed in the WFA suspension. The catalytic reduction of p-NP was inhibited by addition of CaO and Ca(OH) 2 , indicating that higher amount of CaO dissolved from RFA resulted in the inhibition effect. Similar experiments using different oxides (i.e., Al 2 O 3 , SiO 2 , CaO and MgO) revealed no significant reduction of p-NP, which was comparable with Fe 2 O 3 (75.8%). Results from various surface analyses revealed that iron oxides on the surface of WFA can be reduced to elemental Fe nanoparticles, which can effectively reduce p-NP with NaBH 4 . No significant leaching of heavy metals such as Cr, Pb, and As was observed during the catalytic reduction of p-NP and in the suspension of WFA after reaction at pH 3, 5, 7, and 9 for 24 h, which can solve the toxic effect when the FA is used for environmental applications. We also observed a good reusability of WFA during the recycling test, indicating the potential use of WFA for the treatment of wastewater containing reductively degradable pollutants. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mineral concentrations in diets, water, and milk and their value in estimating on-farm excretion of manure minerals in lactating dairy cows.

PubMed

Castillo, A R; St-Pierre, N R; Silva del Rio, N; Weiss, W P

2013-05-01

Thirty-nine commercial dairies in Merced County, California were enrolled in the present study to (1) compare lactating cow mineral intakes (via drinking water and total mixed ration) to the National Research Council (NRC) requirements, (2) evaluate the association between dietary concentrations of minerals with and without drinking water and adjusted for mineral concentrations in milk, and (3) compare 4 different methods to estimate excretion of minerals using either assays or estimations of milk mineral outputs and total daily mineral intake per cow with or without minerals coming from drinking water. Dairies were selected to represent a range of herd milk yields and a range of water mineral contents. Samples of total mixed ration, drinking water, and bulk tank milk were taken on 2 different days, 3 to 7d apart in each farm. Across-farm medians and percentile distributions were used to analyze results. The herd median milk yield interquartile ranged (10th to 90th percentile) from less than 25 to more than 39 kg/d and the concentration of total solids in water interquartile ranged from less than 200 to more than 1,490 mg/L. Including drinking water minerals in the diets increased dietary concentrations by <4% for all minerals except for Na and Cl, which increased by 9.3 and 6.5%, respectively. Concentrations of P and K in milk were essentially the same as the NRC value to estimate lactation requirements. However, NRC milk values of Ca, Cl, and Zn were 10 to 20% greater than dairy farm values; and Na, Cu, Fe, and Mn were no less than 36% below NRC values. Estimated excretion of minerals via manure varied substantially across farms. Farms in the 10th percentile did have 2 to 3 times less estimated mineral excretions than those in the 90th percentile (depending on the mineral). Although including water minerals increased excretion of most minerals, the actual median effect of Ca, Mg, S, Cu, Fe, and Mn was less than 5%, and about 8% for Na and Cl. Replacing assayed concentrations of minerals in milk with NRC constants resulted in reduced estimated excretion of Ca, Na, Cu, Fe, and Zn, but median differences were <5% except for Na which was 7.5%. Results indicate that not including mineral intake via drinking water and not using assayed concentrations of milk minerals lead to errors in estimation manure excretion of minerals (e.g., Ca, Na, Cl, and S). Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Electron impact excitation coefficients for laboratory and astrophysical plasmas

NASA Technical Reports Server (NTRS)

Davis, J.; Kepple, P. C.; Blaha, M.

1976-01-01

Electron impact excitation rate coefficients have been obtained for a number of transitions in highly ionized ions of interest to astrophysical and laboratory plasmas. The calculations were done using the method of distorted waves. Results are presented for various transitions in highly ionized Ne, Na, Al, Si, A, Ca, Ni and Fe.

Metallic elements (Ca, Hg, Fe, K, Mg, Mn, Na, Zn) in the fruiting bodies of Boletus badius.

PubMed

Kojta, Anna K; Falandysz, Jerzy

2016-06-01

The aim of this study was to investigate and compare the levels of eight metallic elements in the fruiting bodies of Bay Bolete (Boletus badius; current name Imleria badia) collected from ten sites in Poland to understand better the value of this popular mushroom as an organic food. Bay Bolete fruiting bodies were collected from the forest area near the towns and villages of Kętrzyn, Poniatowa, Bydgoszcz, Pelplin, Włocławek, Żuromin, Chełmno, Ełk and Wilków communities, as well as in the Augustów Primeval Forest. Elements such as Ca, Fe, K, Mg, Mn, Na and Zn were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP-OES), and mercury by cold vapor atomic absorption spectrometry (CV-AAS). This made it possible to assess the nutritional value of the mushroom, as well as possible toxicological risks associated with its consumption. The results were subjected to statistical analysis (Kruskal-Wallis test, cluster analysis, principal component analysis). Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of classic and microwave-assisted synthesis of benzo-thio crown ethers, and investigation of their ion pair extractions

NASA Astrophysics Data System (ADS)

Calisir, Umit; Çiçek, Baki

2017-11-01

Macrocyclic benzo-thio crown ethers and benzo-oxo crown ethers were prepared using an esterification-ring closing method. These compounds were synthesised using 2,2‧-dithiodibenzoyl chloride, and various glycols and dithiols, in the presence of pyridine base under a nitrogen atmosphere in chloroform. All reactions were performed under reflux condition with conventional heating and microwave (MW) irradiation. The synthesised macrocycles were characterised by FT-IR, 1H NMR, 13C NMR, LC-MS, and elemental analysis methods. Extraction studies have been performed on these original macrocycles using liquid-liquid ion-pair extraction with Li+, Na+, K+, Ni2+, Ca2+, Mg2+, Zn2+, Fe2+,Fe3+, Co3+, Pb2+, Cr3+, Ag+, and Cd2+.The KD, ext.%, ΔG and log KExt values were also calculated. While (U1-U7) ligands exhibits selectivity for Zn2+, Ag+, Ca2+, Pb2+, Fe3+, Cr3+, Co2+, Mg2+, Cd2+, and Ni2+ metal salts, they showed no selectivity for Li+, K+ and Na+ metal salts. Furthermore, Fe3+is the most selective cation for all ligands for competitive extraction. We also observed that microwave heating can have certain benefits over conventional ovens: reaction rate acceleration, milder reaction conditions, higher chemical yield, and lower energy usage. These ligands could be used as metal sensors, enzyme inhibitors, antimicrobial/antifungal agents, and in biological applications.

Fe moments in the pressure-induced collapsed tetragonal phase of (Ca0.67Sr0.33) Fe2As2

NASA Astrophysics Data System (ADS)

Jeffries, Jason; Butch, Nicha; Bradley, Joseph; Xiao, Yuming; Chow, Paul; Saha, Shanta; Kirshenbaum, Kevin; Paglione, Johnpierre

2013-06-01

The tetragonal AEFe2As2 (AE =alkaline earth element) family of iron-based superconductors exhibits magnetic order at ambient pressure and low temperature. Under pressure, the magnetic order is suppressed, and an isostructural volume collapse is induced due to increased As-As bonding across the mirror plane of the structure. This collapsed tetragonal phase has been shown to support superconductivity under some conditions, and theoretical calculations suggest an unconventional origin. Theoretical calculations also reveal that enhanced As-As bonding and the magnitude of the Fe moments are correlated, suggesting that the Fe moments can be quenched in the collapsed tetragonal phase. Whether the Fe moments persist in the collapsed tetragonal phase has implications for the pairing mechanism of the observed, pressure-induced superconductivity in these compounds. We will present pressure- dependent x-ray emission spectroscopy (XES) measurements that probe the Fe moments through the volume collapse transition of (Ca0.67Sr0.33) Fe2As2. These measurements will be compared with previously reported phase diagrams that include superconductivity. Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the US Department of Energy (DOE), National Nuclear Security Administration under Contract No. DE-AC52-07NA27344.

Structure of short-range-ordered iron(III)-precipitates formed by iron(II) oxidation in water containing phosphate, silicate, and calcium

NASA Astrophysics Data System (ADS)

Voegelin, A.; Frommer, J.; Vantelon, D.; Kaegi, R.; Hug, S. J.

2009-04-01

The oxidation of Fe(II) in water leads to the formation of Fe(III)-precipitates that strongly affect the fate of nutrients and contaminants in natural and engineered systems. Examples include the cycling of As in rice fields irrigated with As-rich groundwater or the treatment of drinking water for As removal. Knowledge of the types of Fe(III)-precipitates forming in such systems is essential for the quantitative modeling of nutrient and contaminant dynamics and for the optimization of water purification techniques on the basis of a mechanistic understanding of the relevant biogeochemical processes. In this study, we investigated the local coordination of Fe, P, and Ca in Fe(III)-precipitates formed by aeration of synthetic Fe(II)-containing groundwater with variable composition (pH 7, 2-30 mg/L Fe(II), 2-20 mg/L phosphate-P, 2-20 mg/L silicate-Si, 8 mM Na-bicarbonate or 2.5 mM Ca-&1.5 mM Mg-bicarbonate). After 4 hours of oxidation, Fe(III)-precipitates were collected on 0.2 µm nylon filters and dried. The precipitates were analyzed by Fe K-edge EXAFS (XAS beamline, ANKA, Germany) and by P and Ca K-edge XANES spectroscopy (LUCIA beamline, SLS, Switzerland). The Fe K-edge EXAFS spectra indicated that local Fe coordination in the precipitates systematically shifted with water composition. As long as water contained P, mainly short-range-ordered Fe(III)-phosphate formed (with molar P/Fe ~0.5). In the absence of P, Fe(III) precipitated as hydrous ferric oxide at high Si/Fe>0.5, as ferrihydrite at intermediate Si/Fe, and mainly as lepidocrocite at Si/Fe<0.2. Analysis of the EXAFS by shell-fitting indicated that Fe(III)-phosphates mainly contained mono- or oligomeric (edge- or corner-sharing) Fe and that the linkage between neighboring Fe(III)-octahedra changed from predominantly edge-sharing in Si-rich hydrous ferric oxide to edge- and corner-sharing in ferrihydrite. Electron microscopic data showed that changes in local precipitate structure were systematically reflected in particle morphology and SAED patterns. The P K-edge XANES spectra revealed that phosphate was bound to both Fe as well as Ca (if present). The Ca K-edge XANES spectra showed that the mode of Ca uptake by the Fe(III)-precipitates shifted from mainly adsorption at high Fe/P to coprecipitation at low Fe/P ratio. Despite oversaturation, neither calcite nor hydroxyapatite formed to a significant extent. The results from this study indicated that, depending on water composition, Fe(II) oxidation in natural waters leads to different types of short-range-ordered Fe(III)-phases. Since these phases are expected to differ in their effect on contaminant and nutrient dynamics, their specific physical and chemical properties warrant further research. Methodologically, this work demonstrated the usefulness of investigating the local structure of short-range-ordered precipitates along compositional gradients and by combining the element-selective information from different X-ray absorption edges.

GPU-Accelerated Optical Coherence Tomography Signal Processing and Visualization

NASA Astrophysics Data System (ADS)

Darbrazi, Seyed Hamid Hosseiny

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Albumin and fibronectin adsorption and osteoblast adhesion on titanium oxides

NASA Astrophysics Data System (ADS)

Freitas, Susana Maria Ribeiro e. Sousa Mendes de

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Birefringence and Bragg grating control in femtosecond laser written optical circuits

NASA Astrophysics Data System (ADS)

Fernandes, Luis A.

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Single Point Incremental Forming and Multi-Stage Incremental Forming on Aluminium Alloy 1050

NASA Astrophysics Data System (ADS)

Suriyaprakan, Premika

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Magnetism at the nanoscale: Nanoparticles, nanowires, nanotubes and their ordered arrays

NASA Astrophysics Data System (ADS)

Proenca, Mariana Jesus Paiva

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Improving the characteristics of foundry alloys AlSiCuMg during manufacturing

NASA Astrophysics Data System (ADS)

Fragoso, Bruno Filipe Marques

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Seismic assessment of reinforced concrete frame structures with a new flexibility based element

NASA Astrophysics Data System (ADS)

Arede, Antonio Jose Coelho Dias

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Viscoelastic nanocapsules under flow in microdevices

NASA Astrophysics Data System (ADS)

Cordeiro, Ana Lucinda Teixeira

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Stellar activity in high-precision photometric and spectroscopic transit observations

NASA Astrophysics Data System (ADS)

Oshagh, Mahmoudreza

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Starch and polyethylene based bone-analogue composite biomaterials

NASA Astrophysics Data System (ADS)

Reis, Rui Luis Goncalves dos

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Clinopyroxene based glasses and glass-ceramics for functional applications

NASA Astrophysics Data System (ADS)

Goel, Ashutosh

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Hematite (α-Fe2O3) - A potential Ce4+ carrier in red mud.

PubMed

Bolanz, Ralph M; Kiefer, Stefan; Göttlicher, Jörg; Steininger, Ralph

2018-05-01

Cerium is the most abundant rare earth element (REE) within the waste product of alumina production (red mud), but its speciation in this complex material is still barely understood. Previous studies showed evidence for a correlation between Ce and the main constituent of red mud, iron oxides, which led us to investigate the most abundant iron oxide in red mud, hematite, as possible carrier phase for Ce. Synthetic hematite can incorporate up to 1.70±0.01wt% Ce, which leads to a systematical increase of all unit cell parameters. Investigations by extended X-ray absorption fine structure spectroscopy suggest an incorporation of Ce 4+ O 6 into the hematite structure by a novel atomic arrangement, fundamentally different from the close-range order around Fe 3+ in hematite. Samples of red mud were taken in Lauta (Saxony), Germany and analyzed by powder X-ray diffraction, inductively coupled plasma mass and optical emission spectrometry, electron microprobe analysis and X-ray absorption near-edge structure spectroscopy. Red mud samples consist of hematite (Fe 2 O 3 ) (34-58wt%), sodalite (Na 8 Al 6 Si 6 O 24 Cl 2 ) (4-30wt%), gibbsite (Al(OH) 3 ) (0-25wt%), goethite (FeOOH) (10-23wt%), böhmite (AlOOH) (0-11wt%), rutile (TiO 2 ) (4-8wt%), cancrinite (Na 6 Ca 2 Al 6 Si 6 O 24 (CO 3 ) 2 ) (0-5wt%), nordstrandite (Al(OH) 3 ) (0-5wt%) and quartz (SiO 2 ) (0-4wt%). While the main elemental composition is Fe>Al>Na>Ti>Ca (Si not included), the average concentration of REE is 1109±6mg/kg with an average Ce concentration of 464±3mg/kg. The main carrier of Ce was located in the Fe-rich fine-grained fraction of red mud (0.10wt% Ce 2 O 3 ), while other potential Ce carriers like monazite, lead oxides, secondary Ce-minerals and particles of potentially anthropogenic origin are of subordinated relevance. Cerium in red mud occurs predominantly as Ce 4+ , which further excludes Ce 3+ minerals as relevant sources. Copyright © 2017. Published by Elsevier B.V.

The application of Westcott Formalism k0 NAA method to estimate short and medium lived elements in some Ghanaian herbal medicines complemented by AAS

NASA Astrophysics Data System (ADS)

Ayivor, J. E.; Okine, L. K. N.; Dampare, S. B.; Nyarko, B. J. B.; Debrah, S. K.

2012-04-01

The epithermal neutron shape factor, α of the inner and outer irradiation sites of the Ghana Research Reactor-1 (GHARR-1) was determined obtaining results of 0.105 for the inner (Channel 1) Irradiation site and 0.020 for the outer (channel 6) irradiation site. The neutron temperatures for the inner and outer irradiation sites were 27 °C and 20 °C, respectively. The α values used in Westcott Formalism k0 INAA was applied to determine multi elements in 13 Ghanaian herbal medicines used by the Centre for Scientific Research into Plant Medicine (CSRPM) for the management of various diseases complemented by Atomic Absorption Spectrometry. They are namely Mist. Antiaris, Mist. Enterica, Mist. Morazia, Mist. Nibima, Mist. Modium, Mist. Ninger, Mist Sodenia, Mist. Tonica, Chardicca Powder, Fefe Powder, Olax Powder, Sirrapac powder and Lippia Tea. Concentrations of Al, As, Br, K, Cl, Cu, Mg, Mn, Na and V were determined by short and medium irradiations at a thermal neutron flux of 5×1011 ncm-2 s-1. Fe, Cr, Pb, Co, Ni, Sn, Ca, Ba, Li and Sb were determined using Atomic Absorption Spectrometry (AAS). Ba, Cu, Li and V were present at trace levels whereas Al, Cl, Na, Ca were present at major levels. K, Br, Mg, Mn, Co, Ni, Fe and Sb were also present at minor levels. Arsenic was not detected in all samples. Standard Reference material, IAEA-V-10 Hay Powder was simultaneously analysed with samples. The precision and accuracy of the method using real samples and standard reference materials were evaluated and within ±10% of the reported value. Multivariate analytical techniques, such as cluster analysis (Q-mode and R-mode CA) and principal component analysis (PCA)/factor analysis (FA), have been applied to evaluate the chemical variations in the herbal medicine dataset. All the 13 samples may be grouped into 2 statistically significant clusters (liquid based and powdered herbal medicines), reflecting the different chemical compositions. R-mode CA and PCA suggest common sources for Co, Mg, Fe, Ca, Cr, Ni, Sn, Li and Sb and Na, V, Cl, Mn, Al, Br and K. The PCA/FA identified 3 dominant factors as responsible for the data structure, explaining 84.5% of the total variance in the dataset.

Mass and number size distributions of particulate matter components: comparison of an industrial site and an urban background site.

PubMed

Taiwo, Adewale M; Beddows, David C S; Shi, Zongbo; Harrison, Roy M

2014-03-15

Size-resolved composition of particulate matter (PM) sampled in the industrial town of Port Talbot (PT), UK was determined in comparison to a typical urban background site in Birmingham (EROS). A Micro-Orifice Uniform Deposit Impactor (MOUDI) sampler was deployed for two separate sampling campaigns with the addition of a Grimm optical spectrometer at the PT site. MOUDI samples were analysed for water-soluble anions (Cl(-), NO₃(-) and SO₄(2-)) and cations (Na(+), NH4(+), K(+), Mg(2+) and Ca(2+)) and trace metals (Al, V, Cr, Mn, Fe, Cu, Zn, Sb, Ba and Pb). The PM mass distribution showed a predominance of fine particle (PM₂.₅) mass at EROS whereas the PT samples were dominated by the coarse fraction (PM₂.₅₋₁₀). SO₄(2-), Cl(-), NH4(+), Na(+), NO₃(-), and Ca(2+) were the predominant ionic species at both sites while Al and Fe were the metals with highest concentrations at both sites. Mean concentrations of Cl(-), Na(+), K(+), Ca(2+), Mg(2+), Cr, Mn, Fe and Zn were higher at PT than EROS due to industrial and marine influences. The contribution of regional pollution by sulphate, ammonium and nitrate was greater at EROS relative to PT. The traffic signatures of Cu, Sb, Ba and Pb were particularly prominent at EROS. Overall, PM at EROS was dominated by secondary aerosol and traffic-related particles while PT was heavily influenced by industrial activities and marine aerosol. Profound influences of wind direction are seen in the 72-hour data, especially in relation to the PT local sources. Measurements of particle number in 14 separate size bins plotted as a function of wind direction and speed are highly indicative of contributing sources, with local traffic dominant below 0.5 μm, steelworks emissions from 0.5 to 15 μm, and marine aerosol above 15 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

Characterization of the enhancement effect of Na2CO3 on the sulfur capture capacity of limestones.

PubMed

Laursen, Karin; Kern, Arnt A; Grace, John R; Lim, C Jim

2003-08-15

It has been known for a long time that certain additives (e.g., NaCl, CaCl2, Na2CO3, Fe2O3) can increase the sulfur dioxide capture-capacity of limestones. In a recent study we demonstrated that very small amounts of Na2CO3 can be very beneficial for producing sorbents of very high sorption capacities. This paper explores what contributes to these significant increases. Mercury porosimetry measurements of calcined limestone samples reveal a change in the pore-size from 0.04-0.2 microm in untreated samples to 2-10 microm in samples treated with Na2CO3--a pore-size more favorable for penetration of sulfur into the particles. The change in pore-size facilitates reaction with lime grains throughout the whole particle without rapid plugging of pores, avoiding premature change from a fast chemical reaction to a slow solid-state diffusion controlled process, as seen for untreated samples. Calcination in a thermogravimetric reactor showed that Na2CO3 increased the rate of calcination of CaCO3 to CaO, an effect which was slightly larger at 825 degrees C than at 900 degrees C. Peak broadening analysis of powder X-ray diffraction data of the raw, calcined, and sulfated samples revealed an unaffected calcite size (approximately 125-170 nm) but a significant increase in the crystallite size for lime (approximately 60-90 nm to approximately 250-300 nm) and less for anhydrite (approximately 125-150 nm to approximately 225-250 nm). The increase in the crystallite and pore-size of the treated limestones is attributed to an increase in ionic mobility in the crystal lattice due to formation of vacancies in the crystals when Ca is partly replaced by Na.

The Partial Molar Volume and Compressibility of the FeO Component in Model Basalts (Mixed CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6 Liquids) at 0 GPa: evidence of Fe2+ in 6-fold coordination

NASA Astrophysics Data System (ADS)

Guo, X.; Lange, R. A.; Ai, Y.

2010-12-01

FeO is an important component in magmatic liquids and yet its partial molar volume at one bar is not as well known as that for Fe2O3 because of the difficulty of performing double-bob density measurements under reducing conditions. Moreover, there is growing evidence from spectroscopic studies that Fe2+ occurs in 4, 5, and 6-fold coordination in silicate melts, and it is expected that the partial molar volume and compressibility of the FeO component will vary accordingly. We have conducted both density and relaxed sound speed measurements on four liquids in the An-Di-Hd (CaAl2Si2O8-CaMgSi2O6-CaFeSi2O6) system: (1) Di-Hd (50:50), (2) An-Hd (50:50), (3) An-Di-Hd (33:33:33) and (4) Hd (100). Densities were measured between 1573 and 1838 K at one bar with the double-bob Archimedean method using molybdenum bobs and crucibles in a reducing gas (1%CO-99%Ar) environment. The sound speeds were measured under similar conditions with a frequency-sweep acoustic interferometer, and used to calculate isothermal compressibility. All the density data for the three multi-component (model basalt) liquids were combined with density data on SiO2-Al2O3-CaO-MgO-K2O-Na2O liquids (Lange, 1997) in a fit to a linear volume equation; the results lead to a partial molar volume (±1σ) for FeO =11.7 ± 0.3(±1σ) cm3/mol at 1723 K. This value is similar to that for crystalline FeO at 298 K (halite structure; 12.06 cm3/mol), which suggests an average Fe2+ coordination of ~6 in these model basalt compositions. In contrast, the fitted partial molar volume of FeO in pure hedenbergite liquid is 14.6 ± 0.3 at 1723 K, which is consistent with an average Fe2+ coordination of 4.3 derived from EXAFS spectroscopy (Rossano, 2000). Similarly, all the compressibility data for the three multi-component liquids were combined with compressibility data on SiO2-Al2O3-CaO-MgO liquids (Ai and Lange, 2008) in a fit to an ideal mixing model for melt compressibility; the results lead to a partial molar compressibility (±1σ) for FeO = 2.4 (± 0.3) 10-2 GPa-1 at 1723 K. In contrast, the compressibility of FeO in pure hedenbergite liquid is more than twice as large: 6.3 (± 0.2) 10-2 GPa-1. When these results are combined with density and sound speed data on CaO-FeO-SiO2 liquids at one bar (Guo et al., 2009), a systematic and linear variation between the partial molar volume and compressibility of the FeO component is obtained, which appears to track changes in the average Fe2+ coordination in these liquids. Therefore, the three most important conclusions of this study are: (1) ideal mixing of volume and compressibility does not occur for all FeO-bearing magmatic liquids, owing to changes in Fe2+ coordination, (2) the partial molar volume and compressibility of FeO varies linearly and systematically with Fe2+ coordination, and (3) ideal mixing of volume and compressibility does occur among the three mixed An-Di-Hd liquids, presumably because of a common, average Fe2+ coordination of ~6.

Metal-rich fluid inclusions provide new insights into unconformity-related U deposits (Athabasca Basin and Basement, Canada)

NASA Astrophysics Data System (ADS)

Richard, Antonin; Cathelineau, Michel; Boiron, Marie-Christine; Mercadier, Julien; Banks, David A.; Cuney, Michel

2016-02-01

The Paleoproterozoic Athabasca Basin (Canada) hosts numerous giant unconformity-related uranium deposits. The scope of this study is to establish the pressure, temperature, and composition (P-T-X conditions) of the brines that circulated at the base of the Athabasca Basin and in its crystalline basement before, during and after UO2 deposition. These brines are commonly sampled as fluid inclusions in quartz- and dolomite-cementing veins and breccias associated with alteration and U mineralization. Microthermometry and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data from five deposits (Rabbit Lake, P-Patch, Eagle Point, Millennium, and Shea Creek) complement previously published data for the McArthur River deposit. In all of the deposits investigated, fluid inclusion salinity is between 25 and 40 wt.% NaCl equiv., with compositions displaying a continuum between a "NaCl-rich brine" end-member (Cl > Na > Ca > Mg > K) and a "CaCl2-rich brine" end-member (Cl > Ca ≈ Mg > Na > K). The CaCl2-rich brine has the highest salinity and shows evidence for halite saturation at the time of trapping. The continuum of compositions between the NaCl-rich brine and the CaCl2-rich brine end-members combined with P-T reconstructions suggest anisothermal mixing of the two brines (NaCl-rich brine, 180 ± 30 °C and 800 ± 400 bars; CaCl2-rich brine, 120 ± 30 °C and 600 ± 300 bars) that occurred under fluctuating pressure conditions (hydrostatic to supra-hydrostatic). However, because the two brines were U bearing and therefore oxidized, brine mixing was probably not the driving force for UO2 deposition. Several scenarios are put forward to account for the Cl-Na-Ca-Mg-K composition of the brines, involving combinations of seawater evaporation, halite dissolution, mixing with a halite-dissolution brine, Mg/Ca exchange by dolomitization, Na/Ca exchange by albitization of plagioclase, Na/K exchange by albitization of K-feldspar, and Mg loss by Mg-rich alteration. Finally, the metal concentrations in the NaCl-rich and CaCl2-rich brines are among the highest recorded compared to present-day sedimentary formation waters and fluid inclusions from basin-hosted base metal deposits (up to 600 ppm U, 3000 ppm Mn, 4000 ppm Zn, 6000 ppm Cu, 8000 ppm Pb, and 10,000 ppm Fe). The CaCl2-rich brine carries up to one order of magnitude more metal than the NaCl-rich brine. Though the exact origin of major cations and metals of the two brines remains uncertain, their contrasting compositions indicate that the two brines had distinct flow paths and fluid-rock interactions. Large-scale circulation of the brines in the Athabasca Basin and Basement was therefore a key parameter for metal mobility (including U) and formation of unconformity-related U deposits.

The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins

NASA Astrophysics Data System (ADS)

Mysen, Bjorn O.

2006-05-01

Iron-57 resonant absorption Mössbauer spectroscopy was used to describe the redox relations and structural roles of Fe 3+ and Fe 2+ in meta-aluminosilicate glasses. Melts were formed at 1500 °C in equilibrium with air and quenched to glass in liquid H 2O with quenching rates exceeding 200 °C/s. The aluminosilicate compositions were NaAlSi 2O 6, Ca 0.5AlSi 2O 6, and Mg 0.5AlSi 2O 6. Iron oxide was added in the form of Fe 2O 3, NaFeO 2, CaFe 2O 4, and MgFe 2O 4 with total iron oxide content in the range ˜0.9 to ˜5.6 mol% as Fe 2O 3. The Mössbauer spectra, which were deconvoluted by assuming Gaussian distributions of the hyperfine field, are consistent with one absorption doublet of Fe 2+ and one of Fe 3+. From the area ratios of the Fe 2+ and Fe 3+ absorption doublets, with corrections for differences in recoil-fractions of Fe 3+ and Fe 2+, the Fe 3+/ΣFe is positively correlated with increasing total iron content and with decreasing ionization potential of the alkali and alkaline earth cation. There is a distribution of hyperfine parameters from the Mössbauer spectra of these glasses. The maximum in the isomer shift distribution function of Fe 3+, δFe 3+, ranges from about 0.25 to 0.49 mm/s (at 298 K relative to Fe metal) with the quadrupole splitting maximum, ΔFe 3+, ranging from ˜1.2 to ˜1.6 mm/s. Both δFe 3+ and δFe 2+ are negatively correlated with total iron oxide content and Fe 3+/ΣFe. The dominant oxygen coordination number Fe 3+ changes from 4 to 6 with decreasing Fe 3+/ΣFe. The distortion of the Fe 3+-O polyhedra of the quenched melts (glasses) decreases as the Fe 3+/ΣFe increases. These polyhedra do, however, coexist with lesser proportions of polyhedra with different oxygen coordination numbers. The δFe 2+ and ΔFe 2+ distribution maxima at 298 K range from ˜0.95 to 1.15 mm/s and 1.9 to 2.0 mm/s, respectively, and decrease with increasing Fe 3+/ΣFe. We suggest that these hyperfine parameter values for the most part are more consistent with Fe 2+ in a range of coordination states from 4- to 6-fold. The lower δFe 2+-values for the most oxidized melts are consistent with a larger proportion of Fe 2+ in 4-fold coordination compared with more reduced glasses and melts.

Tularosa Basin Play Fairway Analysis: Water Chemistry

DOE Data Explorer

Adam Brandt

2015-12-15

This shapefile contains 409 well data points on Tularosa Basin Water Chemistry, each of which have a location (UTM), temperature, quartz and Potassium/Magnesium geothermometer; as well as concentrations of chemicals like Mn, Fe, Ba, Sr, Cs, Rb, As, NH4, HCO3, SO4, F, Cl, B, SiO2, Mg, Ca, K, Na, and Li.

Sources of variability in livestock water quality over 5 years in the Northern Great Plains

USDA-ARS?s Scientific Manuscript database

Mineral content of livestock water grazing rangelands can be a source of minerals affecting health and drinkability. To estimate yearly variation in water mineral concentrations, 11 indicators of quality were measured (Ca, Cl, Fe, Fl, Mg, Mn, Na, NO3-N, pH, SO4, total dissolved solids (TDS) and temp...

A model for late Archean chemical weathering and world average river water

NASA Astrophysics Data System (ADS)

Hao, Jihua; Sverjensky, Dimitri A.; Hazen, Robert M.

2017-01-01

Interpretations of the geologic record of late Archean near-surface environments depend very strongly on an understanding of weathering and resultant riverine transport to the oceans. The late Archean atmosphere is widely recognized to be anoxic (pO2,g =10-5 to 10-13 bars; pH2,g =10-3 to 10-5 bars). Detrital siderite (FeCO3), pyrite (FeS2), and uraninite (UO2) in late Archean sedimentary rocks also suggest anoxic conditions. However, whether the observed detrital minerals could have been thermodynamically stable during weathering and riverine transport under such an atmosphere remains untested. Similarly, interpretations of fluctuations recorded by trace metals and isotopes are hampered by a lack of knowledge of the chemical linkages between the atmosphere, weathering, riverine transport, and the mineralogical record. In this study, we used theoretical reaction path models to simulate the chemistry involved in rainwater and weathering processes under present-day and hypothetical Archean atmospheric boundary conditions. We included new estimates of the thermodynamic properties of Fe(II)-smectites as well as smectite and calcite solid solutions. Simulation of present-day weathering of basalt + calcite by world-average rainwater produced hematite, kaolinite, Na-Mg-saponite, and chalcedony after 10-4 moles of reactant minerals kg-1 H2O were destroyed. Combination of the resultant water chemistry with results for granitic weathering produced a water composition comparable to present-day world average river water (WARW). In contrast, under late Archean atmospheric conditions (pCO2,g =10-1.5 and pH2,g =10-5.0 bars), weathering of olivine basalt + calcite to the same degree of reaction produced kaolinite, chalcedony, and Na-Fe(II)-rich-saponite. Late Archean weathering of tonalite-trondhjemite-granodiorite (TTG) formed Fe(II)-rich beidellite and chalcedony. Combining the waters from olivine basalt and TTG weathering resulted in a model for late Archean WARW with the composition Na+-Ca2+-Fe2+-Mg2+-Cl--HCO-3-SiO2,aq. The pH of the water was 6.3 and it is much richer in HCO-3, and in Mg + Fe relative to Ca + Na, compared to present-day WARW. At higher pH2,g (e.g. 10-4.0 bars) organic acid anions could be metastable. Our results are consistent with the thermodynamic stability of Fe(II)-clays, pyrite, uraninite, and, under some conditions, siderite during weathering and riverine transport. Overall, our results provide a basis for assessing the formation of organic hazes and the mobility of trace elements and nutrients due to fluctuations of the late Archean atmosphere.

Effect of different iron compounds on rheological and technological parameters as well as bioaccessibility of minerals in whole wheat bread.

PubMed

Rebellato, Ana Paula; Bussi, Jéssica; Silva, Joyce Grazielle Siqueira; Greiner, Ralf; Steel, Caroline Joy; Pallone, Juliana Azevedo Lima

2017-04-01

This study aimed at investigating the effect of iron compounds used in whole wheat flour (WWF) fortification, both on rheological properties of the dough and on bread technological quality. Furthermore, bioaccessibility of iron (Fe), zinc (Zn) and calcium (Ca) in the final breads was determined. Rheological properties (mainly dough development time, stability, mixing tolerance index, resistance to extension and ratio number) of the dough and the technological quality of bread (mainly oven spring and cut opening) were altered. However, producing roll breads fortified with different iron compounds was still possible. NaFeEDTA (ferric sodium ethylene diamine tetra acetic acid) proved to be the most effective iron compound in the fortification of WWF, since it presented the highest levels of solubility (44.80%) and dialysability (46.14%), followed by microencapsulated ferrous fumarate (FFm). On the other hand, the microencapsulated ferrous sulfate (FSm) and reduced iron presented the lowest solubility (5.40 and 18.30%, respectively) and dialysability (33.12 and 31.79%, respectively). Zn dialysis was positively influenced by NaFeEDTA, FSm, and ferrous fumarate. As for Ca, dialysis was positively influenced by FSm and negatively influenced by FFm. The data indicated that there is a competitive interaction for the absorption of these minerals in whole wheat roll breads, but all studied minerals can be considered bioaccessible. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of marine, terrestrial and anthropogenic sources on ionic and metallic composition of rainwater at a suburban site (northwest coast of Spain)

NASA Astrophysics Data System (ADS)

Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Moscoso-Pérez, Carmen; Blanco-Heras, Gustavo; Turnes-Carou, Isabel; López-Mahía, Purificación; Muniategui-Lorenzo, Soledad; Prada-Rodríguez, Darío

2014-05-01

In the present research, the rainwater chemistry of soluble (SF) and non-soluble (NSF) fractions is studied over a one a half year period (from March 2011 to August 2012) at a suburban site (Oleiros, A Coruña, Spain). The monthly rainfall in this region during the studied period ranged from 10 to 137 mm, while the NSF ranged from 0.9 to 54 mg L-1. More rainfall occurs within October-January. Eighteen samples, which provide information pertaining to the monthly variation in chemistry, were analyzed. Trace metals (Al, As, Ba, Co, Cu, Cr, Fe, Mn, Ni, Pb, Sr, V, Zn) were enclosed in the study of both fractions of the rainwater. Major inorganic ions (Cl-, NO3-, SO42-, Na+, K+, Ca2+, Mg2+ and NH4+) were also enclosed in the study of the SF of the rainwater. After partition coefficients analysis, univariate and principal components analysis (PCA) and air mass back trajectories analysis, three sources were found for the ionic and metal composition of the SF of rainwater; terrestrial (Ca2+, non sea salt SO42-, Al and Fe), marine (Mg2+, Na+, Cl-) and anthropogenic (K+, NH4+, NO3-, Fe, Mn, Pb, Sr, V and Zn). Results also suggest ubiquitous sources for Ba, Co, Cu, Cr and Ni. One source (terrestrial) was found for NSF of rainwater.

Effects of dietary tannins on total and extractable nutrients from manure.

PubMed

Halvorson, J J; Kronberg, S L; Hagerman, A E

2017-08-01

The effects of condensed tannins on N dynamics in ruminants have been a topic of research for some time, but much less work has focused on their impacts on other nutrients in manure. A 4 × 4 Latin square trial was used to determine if intake of sericea lespedeza (; SL; a condensed tannin source), at 0, 10, 20, or 40% of the diet (as-fed basis), would affect concentrations of nutrients in manure and patterns of total excretion when offered with alfalfa (; ALF) to sheep. With SL additions, average daily manure production increased linearly ( ≤ 0.01), from 40 to 50% of the diet mass. The concentrations of total C, total N, soluble P, total and soluble Na, total and soluble S, total and soluble Mn, and total and soluble B in feces increased ( ≤ 0.05) while soluble N, total Ca, total and soluble Mg, soluble Zn, total and soluble Fe, total and soluble Cu decreased ( ≤ 0.02). Total P, total and soluble K, soluble Ca, and total Zn were less affected ( > 0.05). Comparing diets containing 0 to 40% SL, average daily outputs of total C, total N, soluble P, soluble K, total and soluble Na, and total Mn increased linearly ( ≤ 0.01) by 42.0, 71.2, 93.3, 45.2, 111, 148, and 52.4 percentage points, respectively. Total K, total and soluble S, soluble Mn, and total and soluble B increased quadratically ( ≤ 0.02) by 26.1, 52.3, 26.7, 147, 100, and 19.5 percentage points, respectively. Conversely, outputs of soluble Zn and total Fe decreased linearly ( ≤ 0.01), by -51.5 and -24.8 percentage points, while total Ca, total and soluble Mg, soluble Fe, and soluble Cu decreased quadratically ( ≤ 0.05) by -15.7, -12.3, -40.0, -89.9, and -60.3 percentage points, respectively. Outputs of soluble N, total P, soluble Ca, total Zn, and total Cu remained unchanged ( ≥ 0.14). Ratios of manure outputs to feed inputs for C, N, K, and B increased ( ≤ 0.02) but those for P and Mg were unchanged ( ≥ 0.10). Ratios of soluble to total manure outputs (S:O) increased ( ≤ 0.01) for P, Ca, Na, Mn; decreased ( ≤ 0.05) for N, S, Mg, Zn, Fe, Cu, and B; and were unaffected by treatment ( ≤ 0.16) for K. Decreasing S:O ratios are consistent with the formation of complexes that adsorb these nutrients to insoluble fiber fractions of manure and could thus affect mineralization rates. This study suggests that dietary tannins, found in forages like SL, can alter the concentrations, total excretion rates and throughput efficiency of nutrients in manure.

New hydrogen titanium phosphate sulfate electrodes for Li-ion and Na-ion batteries

NASA Astrophysics Data System (ADS)

Zhao, Ran; Mieritz, Daniel; Seo, Dong-Kyun; Chan, Candace K.

2017-03-01

NASICON-type materials with general formula AxM2(PO4)3 (A = Li or Na, M = Ti, V, and Fe) are promising candidates for Li- and Na-ion batteries due to their open three-dimensional framework structure. Here we report the electrochemical properties of hydrogen titanium phosphate sulfate, H0.4Ti2(PO4)2.4(SO4)0.6 (HTPS), a new mixed polyanion material with NASICON structure. Micron-sized HTPS aggregates with crystallite grain size of ca. 23 nm are synthesized using a sol-gel synthesis in an acidic medium. The properties of the as-synthesized HTPS, ball-milled HTPS, and samples prepared as carbon composites using an in-situ glucose decomposition reaction are investigated. A capacity of 148 mAh g-1 corresponding to insertion of 2 Li+ per formula unit is observed in the ball-milled HTPS over the potential window of 1.5-3.4 V vs. Li/Li+. Lithiation at ca. 2.8 and 2.5 V is determined to occur through filling of the M1 and M2 sites, respectively. Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) are used characterize the HTPS before and after cycling. Evaluation of the HTPS in a Na-ion cell is also performed. A discharge capacity of 93 mAh g-1 with sodiation at ca. 2.9 and 2.2 V vs. Na/Na+ is observed.

NiF2/NaF:CaF2/Ca Solid-State High-Temperature Battery Cells

NASA Technical Reports Server (NTRS)

West, William; Whitacre, Jay; DelCastillo, Linda

2009-01-01

Experiments and theoretical study have demonstrated the promise of all-solid-state, high-temperature electrochemical battery cells based on NiF2 as the active cathode material, CaF2 doped with NaF as the electrolyte material, and Ca as the active anode material. These and other all-solid-state cells have been investigated in a continuing effort to develop batteries for instruments that must operate in environments much hotter than can be withstood by ordinary commercially available batteries. Batteries of this type are needed for exploration of Venus (where the mean surface temperature is about 450 C), and could be used on Earth for such applications as measuring physical and chemical conditions in geothermal wells and oil wells. All-solid-state high-temperature power cells are sought as alternatives to other high-temperature power cells based, variously, on molten anodes and cathodes or molten eutectic salt electrolytes. Among the all-solid-state predecessors of the present NiF2/NaF:CaF2/Ca cells are those described in "Solid-State High-Temperature Power Cells" (NPO-44396), NASA Tech Briefs, Vol. 32, No. 5 (May 2008), page 40. In those cells, the active cathode material is FeS2, the electrolyte material is a crystalline solid solution of equimolar amounts of Li3PO4 and LiSiO4, and the active anode material is Li contained within an alloy that remains solid in the intended high operational temperature range.

Characterization of Carbonate Crust from Deep-sea Methane Seeps on the Northern US Atlantic Margin.

NASA Astrophysics Data System (ADS)

Gabitov, R. I.; Borrelli, C.; Buettner, J.; Testa, M.; Garner, B.; Weremeichik, J.; Thomas, J. B.; Wahidi, M.; Thirumalai, R. V. K. G.; Kirkland, B. L.; Skarke, A. D.

2017-12-01

Authigenic carbonate minerals widely occur at the seafloor as carbonate crusts and are often directly linked to microbial activity, about which promotion of carbonate crystal growth and geochemistry are not entirely understood. To evaluate a potential metabolic contribution, studies were conducted on carbonate crust collected from a methane seep and on precipitation experiments which produced inorganic aragonite crystallized at high pressure. Among the samples collected during a NSF sponsored cruise to the North Atlantic Continental Margin of the United States (off of New England) in July-August 2016, we analyzed one carbonate crust sample (AD4835 BB-4522) collected at 39.805860; -69.592593 and at a depth of 1419.6 m. In this crust sample, two textural types of aragonite were identified: 1) groundmass consisting of fine grey crystals (<1 µm in size); 2) veins consisting of white acicular crystals (up to 100 µm in width). In addition, large equant quartz crystals (>100 µm, 24.9 wt%), feldspar (5.6 wt%), and dolomite (3.6 wt%), and trace amount of troilite were identified using XRD, SEM, and optical microscopy. The sample was cut into slabs parallel to crust growth assuming the crust grew in a downward direction. Concentrations of Na, Mg, Al, Si, S, K, Ca, Mn, Fe, Sr, Zr, Ba, and U were measured in the direction parallel to growth of the crust using LA-ICP-MS. Proportions of Si, Al, (Na+K), Mg, S, and Fe in the groundmass suggest the occurrence of sub-micron inclusions of alkali feldspar, and potentially pyroxene, Fe oxide, and Fe sulfide, which were impossible to avoid with the instrument's spatial resolution. The occurrence of micro non-carbonate inclusions causes high elemental concentrations compared to the values expected for aragonite crystallized from seawater. White aragonite acicular crystals were free of silicate and sulfide inclusions, and therefore, yielded lower concentrations of all measured elements except Sr compared to the groundmass. Analyzed Mg and Sr are consistent with published data for deep-sea corals. Also, Sr is similar to experimental data on inorganic aragonite. Mg/Ca, Sr/Ca, Ba/Ca, and U/Ca of the fluid from which acicular aragonite grew were calculated based on partition coefficients from inorganic aragonite precipitated at 100 bars.

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

Integrated light chemical tagging analyses of seven M31 outer halo globular clusters from the Pan-Andromeda Archaeological Survey

NASA Astrophysics Data System (ADS)

Sakari, Charli M.; Venn, Kim A.; Mackey, Dougal; Shetrone, Matthew D.; Dotter, Aaron; Ferguson, Annette M. N.; Huxor, Avon

2015-04-01

Detailed chemical abundances are presented for seven M31 outer halo globular clusters (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated light spectra taken with the Hobby-Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS) - this paper presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal poor ([Fe/H] < -1.5), α-enhanced (though they are possibly less α-enhanced than Milky Way stars at the 1σ level), and show signs of star-to-star Na and Mg variations. The other three globular clusters (H10, H23, and PA17) are more metal rich, with metallicities ranging from [Fe/H] = -1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way globular clusters, and other M31 clusters, H10 and PA17, have moderately low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17's high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud. None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW cloud, and PA53 and PA56 may be associated with the eastern cloud.

Universal single grain amphibole thermobarometer for mantle rocks - preliminary calibration.

NASA Astrophysics Data System (ADS)

Ashchepkov, Igor

2017-04-01

Calibration of S-Al- K-Na-Ca distribution in the structure of the mantle amphiboles (Cr- hornblende, pargasite, kaersutite) using experimental data (Niida, Green, 1999; Wallace Green, 1991, Conceicao, Green, 2004; Medard et al, 2006; Safonov, Butvina, 2013; 2016; Pirard, Hermann, 2015 etc) allows to obtain an equation for pressure estimates in 0.5 - 4.5 GPa interval. Regression calculated pressures with experimental values (R 0.82) and precision 5 kbar allow to use barometer for a wide range of mantle rocks from peridotite to pyroxenites and megacrystals. For the higher pressures (Cr- pargasite richterite) calibration is carried by the cross- correlations with the estimates calculated for the natural associations obtained using clino- and orthopyroxene. IT was used KD =Si/(8-Al-2.2*Ti)*(Na+K))/Ca for the following equation: P(GPa)=0.0035*(4+K/(Na+K))*2*Mg)/Fe+3.75*(K+Na)/Ca))*KD*ToK**0.75/ (1+3.32*Fe)-ln(1273/ToK*5*(8*Mg-Al*2 +3*Ti+8*Cr+3*K)/10 Th advantage of this barometer comparing with the previous (Ridolfi, Renzulli, 2012) is that is working with all mantle amphibole types. For the calculations of the PT parameters of the natural xenocrysts it was used monomineral version of Gar-Amph termometer (Ravna et al., 2000) in combination with the received barometer. Contents of Ca- Mg and Fe in associated garnets were calculated usinf the regressions obtained from natural and experimental associations. Aplication of the mantle amphibole thermobarometry for the reconstruction of sections of the cratonic mantle lithosphere of Yakutia show that amphibloles are distributed in various parts of mantle sections in deifferent mantle terranes of Yakutia. The most abundant amphoboles from Alakite region are distributed within all mantle section. In the SCLM beneat Yubileyaya pipe thehalf of them belong to the spinel garnet facie refering to the upper pyroxenitic suit and Cr- hornblende - mica viens. The second group reffer to the eclogite pyroxenite layer in the middle part of SCLM and the third group refer to richterites form the depleted manle peridotites. In SCLM beneat the Sytykanskaya they are more frequent and trace through all the mantle layers. In SCLM beneat the Aykhal they mostly are from the lower and in Komsomolskaya from the middle SCLM parts. In Daldyn field rare amdphibles from Dalnaya are Fe- enriched pargasites belonging to the Ilm bearing peridotites in middle SCLM part as well as in SCLM beneath thr Udachnaya. But there are Fe- low amphiboles substitutng the orthopyroxenes. In Zarnitsa the Cr - hornblendes occur in shallow garnet pyroxenites. One deep seated richterite substitute garnet grains. Rare amphiboles were detedted in Mirninsky filed in Internatiolnaya pipe and reffer to the resorbed and deformed granets from the Garnet -Spinel facies and from 4.0 GPa boundary. Amphiboles are frequent in the SCLM from the northern part of Siberian craton. In SCLM beneath the Kharmai the Fe- encriched varietes are from the Moho boundary. Common Cr-pargasite occurs to 3 GPa in Obnazhennay, pipe, Kharamai field In mantle SCLM beneath Obnazhennaya pipe and circum Anabr region friquent Cr- pargasies and horblendes refer to the relatively hot branch of mantle lithosphere and probably corresponds to the Triassic mantle reactivation. Mantle Cr- hornbleneds occurs on most upper part of the mantle column beneath Quaternary mujeritic Bartoy vocanoes in Transbaikal. The pargasites and kaersutites in this locality refer to more heated conditions and could be found to 2.0 GPa. Grant RFBR 16.-05-000860

Concentrations of asbestos fibers and metals in drinking water caused by natural crocidolite asbestos in the soil from a rural area.

PubMed

Wei, Binggan; Ye, Bingxiong; Yu, Jiangping; Jia, Xianjie; Zhang, Biao; Zhang, Xiuwu; Lu, Rongan; Dong, Tingrong; Yang, Linsheng

2013-04-01

Asbestos fibers and metals in drinking water are of significant importance to the field of asbestos toxicology. However, little is known about asbestos fibers and metals in drinking water caused by naturally occurring asbestos. Therefore, concentrations of asbestos fibers and metals in well and surface waters from asbestos and control areas were measured by scanning electron microscopy (SEM), inductively coupled plasma (ICP) optical emission spectrometer, and ICP-mass spectrometry in this study. The results indicated that the mean concentration of asbestos fibers was 42.34 millions of fibers per liter by SEM, which was much higher than the permission exposure level. The main compositions of both asbestos fibers in crocidolite mineral and in drinking water were Na, Mg, Fe, and Si based on energy dispersive X-ray analysis. This revealed that the drinking water has been contaminated by asbestos fibers from crocidolite mineral in soil and rock. Except for Cr, Pb, Zn, and Mn, the mean concentrations of Ni, Na, Mg, K, Fe, Ca, and SiO2 were much higher in both surface water and well waters from the asbestos area than in well water from the control area. The results of principal component and cluster analyses indicated that the metals in surface and well waters from the asbestos area were significantly influenced by crocidolite mineral in soil and rock. In the asbestos area, the mean concentrations of asbestos fibers and Ni, Na, Mg, K, Fe, Ca, and SiO2 were higher in surface and well waters, indicating that asbestos fibers and the metals were significantly influenced by crocidolite in soil and rock.

A new method of calculating electrical conductivity with applications to natural waters

USGS Publications Warehouse

McCleskey, R. Blaine; Nordstrom, D. Kirk; Ryan, Joseph N.; Ball, James W.

2012-01-01

A new method is presented for calculating the electrical conductivity of natural waters that is accurate over a large range of effective ionic strength (0.0004–0.7 mol kg-1), temperature (0–95 °C), pH (1–10), and conductivity (30–70,000 μS cm-1). The method incorporates a reliable set of equations to calculate the ionic molal conductivities of cations and anions (H+, Li+, Na+, K+, Cs+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, F-, Cl-, Br-, SO42-, HCO3-, CO32-, NO3-, and OH-), environmentally important trace metals (Al3+, Cu2+, Fe2+, Fe3+, Mn2+, and Zn2+), and ion pairs (HSO4-, NaSO4-, NaCO3-, and KSO4-). These equations are based on new electrical conductivity measurements for electrolytes found in a wide range of natural waters. In addition, the method is coupled to a geochemical speciation model that is used to calculate the speciated concentrations required for accurate conductivity calculations. The method was thoroughly tested by calculating the conductivities of 1593 natural water samples and the mean difference between the calculated and measured conductivities was -0.7 ± 5%. Many of the samples tested were selected to determine the limits of the method and include acid mine waters, geothermal waters, seawater, dilute mountain waters, and river water impacted by municipal waste water. Transport numbers were calculated and H+, Na+, Ca2+, Mg2+, NH4+, K+, Cl-, SO42-, HCO3-, CO32-, F-, Al3+, Fe2+, NO3-, and HSO4- substantially contributed (>10%) to the conductivity of at least one of the samples. Conductivity imbalance in conjunction with charge imbalance can be used to identify whether a cation or an anion measurement is likely in error, thereby providing an additional quality assurance/quality control constraint on water analyses.

A new method of calculating electrical conductivity with applications to natural waters

NASA Astrophysics Data System (ADS)

McCleskey, R. Blaine; Nordstrom, D. Kirk; Ryan, Joseph N.; Ball, James W.

2012-01-01

A new method is presented for calculating the electrical conductivity of natural waters that is accurate over a large range of effective ionic strength (0.0004-0.7 mol kg-1), temperature (0-95 °C), pH (1-10), and conductivity (30-70,000 μS cm-1). The method incorporates a reliable set of equations to calculate the ionic molal conductivities of cations and anions (H+, Li+, Na+, K+, Cs+, NH4+, Mg2+, Ca2+, Sr2+, Ba2+, F-, Cl-, Br-, SO42-, HCO3-, CO32-, NO3-, and OH-), environmentally important trace metals (Al3+, Cu2+, Fe2+, Fe3+, Mn2+, and Zn2+), and ion pairs (HSO4-, NaSO4-, NaCO3-, and KSO4-). These equations are based on new electrical conductivity measurements for electrolytes found in a wide range of natural waters. In addition, the method is coupled to a geochemical speciation model that is used to calculate the speciated concentrations required for accurate conductivity calculations. The method was thoroughly tested by calculating the conductivities of 1593 natural water samples and the mean difference between the calculated and measured conductivities was -0.7 ± 5%. Many of the samples tested were selected to determine the limits of the method and include acid mine waters, geothermal waters, seawater, dilute mountain waters, and river water impacted by municipal waste water. Transport numbers were calculated and H+, Na+, Ca2+, Mg2+, NH4+, K+, Cl-, SO42-, HCO3-, CO32-, F-, Al3+, Fe2+, NO3-, and HSO4-substantially contributed (>10%) to the conductivity of at least one of the samples. Conductivity imbalance in conjunction with charge imbalance can be used to identify whether a cation or an anion measurement is likely in error, thereby providing an additional quality assurance/quality control constraint on water analyses.

Templated assembly of BiFeO3 nanocrystals into 3D mesoporous networks for catalytic applications

NASA Astrophysics Data System (ADS)

Papadas, I. T.; Subrahmanyam, K. S.; Kanatzidis, M. G.; Armatas, G. S.

2015-03-01

The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4.The self-assembly of uniform nanocrystals into large porous architectures is currently of immense interest for nanochemistry and nanotechnology. These materials combine the respective advantages of discrete nanoparticles and mesoporous structures. In this article, we demonstrate a facile nanoparticle templating process to synthesize a three-dimensional mesoporous BiFeO3 material. This approach involves the polymer-assisted aggregating assembly of 3-aminopropanoic acid-stabilized bismuth ferrite (BiFeO3) nanocrystals followed by thermal decomposition of the surfactant. The resulting material consists of a network of tightly connected BiFeO3 nanoparticles (~6-7 nm in diameter) and has a moderately high surface area (62 m2 g-1) and uniform pores (ca. 6.3 nm). As a result of the unique mesostructure, the porous assemblies of BiFeO3 nanoparticles show an excellent catalytic activity and chemical stability for the reduction of p-nitrophenol to p-aminophenol with NaBH4. Electronic supplementary information (ESI) available: IR spectra and TG profiles of as-made BiFeO3 NPs and MBFA samples, TEM images of 3-APA-capped BiFeO3 NPs, EDS spectrum of MBFAs, N2 adsorption-desorption isotherms of randomly aggregated BiFeO3 NPs and catalytic data for 4-NP reduction by MBFAs and other nanostructured catalysts. See DOI: 10.1039/c5nr00185d

Oxygen isotope geochemistry of the amphiboles: isotope effects of cation substitutions in minerals

NASA Astrophysics Data System (ADS)

Kohn, Matthew J.; Valley, John W.

1998-06-01

The occurrence of coexisting amphiboles in rocks and the likelihood of concurrent isotope closure allows equilibrium oxygen isotope fractionations among the amphiboles to be recovered from natural samples. Oxygen isotope analyses of mineral separates using laser fluorination show that coexisting amphiboles increasingly partition 18O in the order: hornblende ≪ gedrite < cummingtonite ≤ anthophyllite. The observed fractionations at ˜575°C are: Δ(Ged-Hbl) = 0.8‰, Δ(Cum-Hbl) = 0.9, Δ(Cum-Ged) = 0.2, Δ(Ath-Ged) = 0.3, and Δ(Ath-Hbl) > 0.9. Previously published data for hornblende, actinolite, glaucophane, and garnet show that Δ(Act-Hbl) ˜ 0.2, Δ(Gln-Grt) ≫ 1, and Δ(Hbl-Grt) ˜ 0. Thus, glaucophane strongly partitions 18O relative to the calcic amphiboles. The fractionation between two amphiboles of arbitrary composition can be predicted from the known fractionations for mica endmembers, pyroxene endmembers, and exchange components such as CaAl(NaSi) -1, NaAl(CaMg) -1, CaMg -1, MgFe -1, FeMn -1, KNa -1, KAl( Si) -1, and Fe 3+Al -1. Applications of the exchange component method reproduce measured amphibole fractionations to within ±0.1 to ±0.2‰, whereas other predictive methods cause misfit for typical metamorphic hornblende of ≥0.5‰ at 575°C. Although the isotope effects of cation exchanges may be small at high-T, they magnify dramatically for minerals formed in surficial, diagenetic, and low-T metamorphic environments. Different composition clays are predicted to have equilibrium δ 18O differences of 2-9‰. If the isotope fractionation can be determined for one mineral endmember, then calibrated exchanges allow accurate prediction of the isotope fractionations for intermediate compositions of most ortho-, ring-, chain-, and sheet-silicates.

The effect of age and gender on 38 chemical element contents in human iliac crest investigated by instrumental neutron activation analysis.

PubMed

Zaichick, Sofia; Zaichick, Vladimir

2010-01-01

To understand the role of major, minor, and trace elements in the etiology of bone diseases including osteoporosis, it is necessary to determine the normal levels and age-related changes of bone chemical elements. The effect of age and gender on 38 chemical element contents in intact iliac crest of 84 apparently healthy 15-55 years old women (n=38) and men (n=46) was investigated by neutron activation analysis. Mean values (M+/-SEM) for mass fraction (on dry weight basis) of Ca, Cl, Co, Fe, K, Mg, Mn, Na, P, Rb, Sr, and Zn for both female and male taken together were Ca - 169+/-3g/kg, Cl - 1490+/-43 mg/kg, Co - 0.0073+/-0.0024 mg/kg, Fe - 177+/-24 mg/kg, K - 1820+/-79 mg/kg, Mg - 1840+/-48 mg/kg, Mn - 0.316+/-0.013 mg/kg, Na - 4970+/-87 mg/kg, P - 79.7+/-1.5 g/kg, Rb - 1.89+/-0.22 mg/kg, Sr - 312+/-15 mg/kg, and Zn - 65.9+/-3.4 mg/kg, respectively. The upper limit of mean contents of Cs, Eu, Hg, Sb, Sc, and Se were Cs < or = 0.09 mg/kg, Eu < or = 0.005 mg/kg, Hg < or = 0.005 mg/kg, Sb < or = 0.004 mg/kg, Sc < or = 0.001 mg/kg, and Se < or = 0.1mg/kg, respectively. In all bone samples the contents of Ag, As, Au, Ba, Br, Cd, Ce, Cr, Gd, Hf, La, Lu, Nd, Sm, Ta, Tb, Th, U, Yb, and Zr were under detection limits. The Ca, Mg, and P contents decrease with age, regardless of gender. Higher Ca, Mg, P, and Sr mass fractions as well as lower Fe content are typical of female iliac crest as compared to those in male bone. Copyright 2009 Elsevier GmbH. All rights reserved.

Timescales between mantle metasomatism and kimberlite ascent indicated by diffusion profiles in garnet crystals from peridotite xenoliths

NASA Astrophysics Data System (ADS)

Jollands, Michael C.; Hanger, Brendan J.; Yaxley, Gregory M.; Hermann, Jörg; Kilburn, Matthew R.

2018-01-01

Rare garnet crystals from a peridotite xenolith from the Wesselton kimberlite, South Africa, have distinct zones related to two separate episodes of mantle metasomatism. The garnet cores were firstly depleted through melt extraction, then equilibrated during metasomatism by a potentially diamond-forming carbonate-bearing or proto-kimberlitic fluid at 1100-1300 °C and 4.5-5.5 GPa. The garnet rim chemistry, in contrast, is consistent with later overgrowth in equilibrium with a kimberlite at around 1025 ± 25 °C and 4.2 ± 0.5 GPa. This suggests that the rock was physically moved upwards by up to tens of kilometres between the two metasomatic episodes. Preserved high Ca, Al and Cr contents in orthopyroxenes suggest this uplift was tectonic, rather than magmatic. Diffusion profiles were measured over the transitions between garnet cores and rims using electron microprobe (Mg, Ca, Fe for modelling, plus Cr, Mn, Ti, Na, Al) and nano Secondary Ion Mass Spectrometry (NanoSIMS; 89Y, along with 23Na, Ca, Cr, Fe, Mn and Ti) analyses. The short profile lengths (generally <10 μm) and low Y concentrations (0.2-60 ppm) make the NanoSIMS approach preferable. Diffusion profiles at the interface between the zones yield constraints on the timescale between the second metasomatic event and eruption of the kimberlite magma that brought the xenolith to the surface. The time taken to form the diffusion profiles is on the order of 25 days to 400 yr, primarily based on modelling of Y diffusion along with Ca, Fe and Mg (multicomponent diffusion) profiles. These timescales are too long to be produced by the interaction of the mantle xenolith with the host kimberlite magma during a single-stage ascent to the crust (hours to days). The samples offer a rare opportunity to study metasomatic processes associated with failed eruption attempts in the cratonic lithosphere.

Sintering and crystallization behavior of CaMgSi{sub 2}O{sub 6}-NaFeSi{sub 2}O{sub 6} based glass-ceramics

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

Goel, Ashutosh; Kansal, Ishu; Dipartimento di Ingegneria dei Materiali e dell'Ambiente, Facolta di Ingegneria, Universita di Modena e Reggio Emilia, 41100 Modena

2009-11-01

We report on the synthesis, sintering, and crystallization behaviors of a glass with a composition corresponding to 90 mol % CaMgSi{sub 2}O{sub 6}-10 mol % NaFeSi{sub 2}O{sub 6}. The investigated glass composition crystallized superficially immediately after casting of the melt and needs a high cooling rate (rapid quenching) in order to produce an amorphous glass. Differential thermal analysis and hot-stage microscopy were employed to investigate the glass forming ability, sintering behavior, relative nucleation rate, and crystallization behavior of the glass composition. The crystalline phase assemblage in the glass-ceramics was studied under nonisothermal heating conditions in the temperature range of 850-950more » deg. C in both air and N{sub 2} atmosphere. X-ray diffraction studies adjoined with the Rietveld-reference intensity ratio method were employed to quantify the amount of crystalline phases, while electron microscopy was used to shed some light on the microstructure of the resultant glass-ceramics. Well sintered glass-ceramics with diopside as the primary crystalline phase were obtained where the amount of diopside varied with the heating conditions.« less

Understanding the magnetic behavior of heat treated CaO-P2O5-Na2O-Fe2O3-SiO2 bioactive glass using electron paramagnetic resonance studies

NASA Astrophysics Data System (ADS)

Shankhwar, Nisha; Kothiyal, G. P.; Srinivasan, A.

2014-09-01

Bioactive glass of composition 41CaO-44SiO2-4P2O5-8Fe2O3-3Na2O has been heat treated in the temperature (TA) range of 750-1150 °C for time periods (tA) ranging from 1 h to 3 h to yield magnetic bioactive glass ceramics (MBCs). X-ray diffraction studies indicate the presence of bone mineral (hydroxyapatite and wollastonite) and magnetic (magnetite and α-hematite) phases in nanocrystalline form in the MBCs. Electron paramagnetic resonance (EPR) study was carried out to understand the variation in saturation magnetization and coercivity of the MBCs with TA and tA. These studies reveal the nature and amount of iron ions present in the MBCs and their interaction in the glassy oxide matrix as a function of annealing parameters. The deterioration in the magnetic properties of the glass heat treated above 1050 °C is attributed to the crystallization of the non-magnetic α-hematite phase. These results are expected to be useful in the application of these MBCs as thermoseeds in hyperthermia treatment of cancer.

Measuring the content of 17 elements in the flesh of Prunus cerasifera and its cultivars by ICP-MS.

PubMed

Shen, Jing; Xue, Hai-Yan; Li, Gai-Ru; Lu, Yi; Yao, Jun

2014-09-01

The present study compared the contents of inorganic elements in the pulp of purple, red, and yellow Prunus cerasifera with its cultivars. A method was established for the analysis of 17 kinds of trace elements (K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Be, Li, Se, Sr, Cr, Pb, Cd, As and Hg) in the flesh of Prunus cerasifera by microwave digestion-ICP-MS. The detection method is simple and quick, yet shoes high precision and high sensitivity. The recovery rate of 17 elements ranged, from 93.5% to 110.4%. The analysis results showed that the contents of 17 elements in the flesh of purple, red, and yellow Prunus cerasifera and its cultivars are similar, containing extremely rich K elements (as high as 1 per thousand) and higher contents of Ca, Mg, Na, Fe and Mn. The contents of Cu, Zn, Li, Se, Sr and Cr are also present. The contents of Pb, Cd, As, Hg and other harmful element are either very low or not detectable. The experimental results for the study of trace elements in pulp of Prunus cerasifera and its cultivars provide empirical data for. future research in this area.

Source identification of particulate matter in a semi-urban area of Malaysia using multivariate techniques.

PubMed

Wahid, N B A; Latif, M T; Suan, L S; Dominick, D; Sahani, M; Jaafar, S A; Mohd Tahir, N

2014-03-01

This study aims to determine the composition and sources of particulate matter with an aerodynamic diameter of 10 μm or less (PM10) in a semi-urban area. PM10 samples were collected using a high volume sampler. Heavy metals (Fe, Zn, Pb, Mn, Cu, Cd and Ni) and cations (Na(+), K(+), Ca(2+) and Mg(2+)) were detected using inductively coupled plasma mass spectrometry, while anions (SO4 (2-), NO3 (-), Cl(-) and F(-)) were analysed using Ion Chromatography. Principle component analysis and multiple linear regressions were used to identify the source apportionment of PM10. Results showed the average concentration of PM10 was 29.5 ± 5.1 μg/m(3). The heavy metals found were dominated by Fe, followed by Zn, Pb, Cu, Mn, Cd and Ni. Na(+) was the dominant cation, followed by Ca(2+), K(+) and Mg(2+), whereas SO4 (2-) was the dominant anion, followed by NO3 (-), Cl(-) and F(-). The main sources of PM10 were the Earth's crust/road dust, followed by vehicle emissions, industrial emissions/road activity, and construction/biomass burning.

Silver Nanoparticle-Enhanced Resonance Raman Sensor of Chromium(III) in Seawater Samples.

PubMed

Ly, Nguyễn Hoàng; Joo, Sang-Woo

2015-04-29

Tris(hydroxymethyl)aminomethane ethylenediaminetetraacetic acid (Tris-EDTA), upon binding Cr(III) in aqueous solutions at pH 8.0 on silver nanoparticles (AgNPs), was found to provide a sensitive and selective Raman marker band at ~563 cm-1, which can be ascribed to the metal-N band. UV-Vis absorption spectra also supported the aggregation and structural change of EDTA upon binding Cr(III). Only for Cr(III) concentrations above 500 nM, the band at ~563 cm-1 become strongly intensified in the surface-enhanced Raman scattering spectra. This band, due to the metal-EDTA complex, was not observed in the case of 50 mM of K+, Cd2+, Mg2+, Ca2+, Mn2+, Co2+, Na+, Cu2+, NH4+, Hg2+, Ni2+, Fe3+, Pb2+, Fe2+, and Zn2+ ions. Seawater samples containing K, Mg, Ca, and Na ion concentrations higher than 8 mM also showed the characteristic Raman band at ~563 cm-1 above 500 nM, validating our method. Our approach may be useful in detecting real water samples by means of AgNPs and Raman spectroscopy.

[Distribution of chemical elements in whole blood and plasma].

PubMed

Barashkov, G K; Zaĭtseva, L I; Kondakhchan, M A; Konstantinova, E A

2003-01-01

The distribution factor (Fd) of 35 elements of plasma and whole blood in 26 healthy men and women was detected by ICP-OES. Usilig this parameter the elements were subdivided in 3 pools. 9 of them have Fd higher than 1.5 ("elements of plasma"-Ag, Ca, Cu, In, Li, Na, Se, Si, Sr); 6 have lower than 0.5 ("elements of blood cells"-Fe, K, Mn, Ni, V, Zn), other 20-about 1 ("blood elements"). Fd of all elements depends on ionic radius. Elements of 2nd sub-groups of all groups of Mendeleev's periodic table ("heavy metals") depend on the similar law: "with growing of ionic radius the concentration of elements in plasma enhances". In alkaline metals Fd depends on the opposite law:" with growing of ionic radius of alkaline metal the quantity of elements in blood cells enhance". Dependence of Fd on the value of atomic mass in periods or in exterior electronic cloud (s-, p-, d-, f-) was not established. The table of distribution of all detected elements in whole blood in relation to 8 macroelements (Ca, Mg, K, Na, S, P, Fe, Zn,) is presented, as a basic diagnostic criteria in metal-ligand homeostasis disturbance.

Davinciite, Na12K3Ca6Fe{3/2+}Zr3(Si26O73OH)Cl2, a New K,Na-Ordered mineral of the eudialyte group from the Khibiny Alkaline Pluton, Kola Peninsula, Russia

NASA Astrophysics Data System (ADS)

Khomyakov, A. P.; Nechelyustov, G. N.; Rastsvetaeva, R. K.; Rozenberg, K. A.

2013-12-01

This paper presents a description of a new zirconosilicate of the eudialyte group, which was named davinciite in honor of Leonardo da Vinci (1452-1519), a famous Italian scientist, painter, sculptor and architect. The new mineral has been found in hyperagpaitic pegmatite at the Rasvumchorr Mountain, Khibiny Pluton, Kola Peninsula, as relict inclusions, up to 1-2 mm in size in a rastsvetaevite matrix. It is associated with nepheline, sodalite, potassium feldspar, delhayelite, aegirine, shcherbakovite, villiaumite, nitrite, nacaphite, rasvumite, and djerfisherite. Davinciite is dark lavender and transparent, with a vitreous luster and white streak. The new mineral is brittle, with conchoidal fracture; the Mohs' hardness is 5. No indications of cleavage or parting were observed. The measured density is 2.82(2) g/cm3 (volumetric method); the calculated density is 2.848 g/cm3. Davinciite is optically uniaxial, positive; ω = 1.603(2), ɛ = 1.605(2). It is nonpleochroic and nonfluorescent in UV light. The new mineral slowly breaks down and gelates in 50% HCl and HNO3. It is trigonal, space group R3m. The unit-cell dimensions are a = 14.2956(2), c = 30.0228(5) Å, V=5313.6(2) Å3. The strongest reflections in the X-ray powder diffraction pattern [ d, Å ( I, %) ( hkl)] are as follows: 2.981(100)(315), 2.860(96)(404), 4.309(66)(205), 3.207(63)(208), 6.415(54)(104), 3.162(43)(217). The chemical composition (electron microprobe, H2O calculated from X-ray diffraction data) is as follows, wt %: 12.69 Na2O, 3.53 K2O, 11.02 CaO, 0.98 SrO, 0.15 BaO, 5.33 FeO, 0.37 MnO, 0.07 Al2O3, 51.20 SiO2, 0.39 TiO2, 11.33 ZrO2, 0.21HfO2, 0.09 Nb2O5, 1.89 Cl, 0.93H2O, -O = Cl2 0.43; total is 99.75. The empirical formula calculated on the basis of Si + Al + Zr + Hf + Ti + Nb = 29 ( Z = 3) is (Na1l.75Sr0.29Ba0.03)Σ12.07(K2.28Na0.72)Σ3Ca5.99(Fe2.26Mn0.16)Σ2.42(Zr2.80Ti0.15Hf0.03Nb0.02) Σ3(Si1.96Al0.04)Σ2[Si3O9]2 [Si9O27]2[(OH)1.42O0.58]Σ2[Cl1.62(H2O)0.38]Σ2 · 0.48H2O. The simplified formula is Na12K3Ca6Fe{3/2+}Zr3(Si26O73OH)Cl2. The IR-spectrum is given and the crystal structure is described. The position of davinciite in the crystal chemical taxonomy of the eudialyte group is shown, and its relationships with the other eudialyte-group minerals (acentric eudialyte, andrianovite, and kentbrooksite) are characterized. The type material of davinciite is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

Particulate matter and polycyclic aromatic hydrocarbons from forest fires: impacts on air quality and occupational risks assessment

NASA Astrophysics Data System (ADS)

Oliveira, Marta Madalena Marques de

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Reciprocal interaction between human microvascular endothelial cells and mesenchymal stem cells on macroporous granules of nanostructured-hydroxyapatite agglomerates

NASA Astrophysics Data System (ADS)

Laranjeira, Marta de Sousa

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Analysis of vegetation dynamics using time-series vegetation index data from Earth observation satellites

NASA Astrophysics Data System (ADS)

Rodrigues, Arlete da Silva

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Biological effects of polyacrylic acid-coated and non-coated superparamagnetic iron oxide nanoparticles in in vitro and in vivo experimental models

NASA Astrophysics Data System (ADS)

Couto, Diana Manuel Mocho de Bastos

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Impact evaluation of the large scale integration of electric vehicles in the security of supply

NASA Astrophysics Data System (ADS)

Bremermann, Leonardo Elizeire

As piroxenas sao um vasto grupo de silicatos minerais encontrados em muitas rochas igneas e metamorficas. Na sua forma mais simples, estes silicatos sao constituidas por cadeias de SiO3 ligando grupos tetrahedricos de SiO4. A formula quimica geral das piroxenas e M2M1T2O6, onde M2 se refere a catioes geralmente em uma coordenacao octaedrica distorcida (Mg2+, Fe2+, Mn2+, Li+, Ca2+, Na+), M1 refere-se a catioes numa coordenacao octaedrica regular (Al3+, Fe3+, Ti4+, Cr3+, V3+, Ti3+, Zr4+, Sc3+, Zn2+, Mg2+, Fe2+, Mn2+), e T a catioes em coordenacao tetrahedrica (Si4+, Al3+, Fe3+). As piroxenas com estrutura monoclinica sao designadas de clinopiroxenes. A estabilidade das clinopyroxenes num espectro de composicoes quimicas amplo, em conjugacao com a possibilidade de ajustar as suas propriedades fisicas e quimicas e a durabilidade quimica, tem gerado um interesse mundial devido a suas aplicacoes em ciencia e tecnologia de materiais. Este trabalho trata do desenvolvimento de vidros e de vitro-cerâmicos baseadas de clinopiroxenas para aplicacoes funcionais. O estudo teve objectivos cientificos e tecnologicos; nomeadamente, adquirir conhecimentos fundamentais sobre a formacao de fases cristalinas e solucoes solidas em determinados sistemas vitro-cerâmicos, e avaliar a viabilidade de aplicacao dos novos materiais em diferentes areas tecnologicas, com especial enfase sobre a selagem em celulas de combustivel de oxido solido (SOFC). Com este intuito, prepararam-se varios vidros e materiais vitro-cerâmicos ao longo das juntas Enstatite (MgSiO3) - diopsidio (CaMgSi2O6) e diopsidio (CaMgSi2O6) - Ca - Tschermak (CaAlSi2O6), os quais foram caracterizados atraves de um vasto leque de tecnicas. Todos os vidros foram preparados por fusao-arrefecimento enquanto os vitro-cerâmicos foram obtidos quer por sinterizacao e cristalizacao de fritas, quer por nucleacao e cristalizacao de vidros monoliticos. Estudaram-se ainda os efeitos de varias substituicoes ionicas em composicoes de diopsidio contendo Al na estrutura, sinterizacao e no comportamento durante a cristalizacao de vidros e nas propriedades dos materiais vitro-cerâmicos, com relevância para a sua aplicacao como selantes em SOFC. Verificou-se que Foi observado que os vidros/vitro-cerâmicos a base de enstatite nao apresentavam as caracteristicas necessarias para serem usados como materiais selantes em SOFC, enquanto as melhores propriedades apresentadas pelos vitro-cerâmicos a base de diopsidio qualificaram-nos para futuros estudos neste tipo de aplicacoes. Para alem de investigar a adequacao dos vitro-cerâmicos a base de clinopyroxene como selantes, esta tese tem tambem como objetivo estudar a influencia dos agentes de nucleacao na nucleacao em volume dos vitro-cerâmicos resultantes a base de diopsidio, de modo a qualifica-los como potenciais materiais hopedeiros de residuos nucleares radioactivos.

Energy dispersive X-ray fluorescence spectrometry for the direct multi-element analysis of dried blood spots

NASA Astrophysics Data System (ADS)

Marguí, E.; Queralt, I.; García-Ruiz, E.; García-González, E.; Rello, L.; Resano, M.

2018-01-01

Home-based collection protocols for clinical specimens are actively pursued as a means of improving life quality of patients. In this sense, dried blood spots (DBS) are proposed as a non-invasive and even self-administered alternative to sampling whole venous blood. This contribution explores the potential of energy dispersive X-ray fluorescence spectrometry for the simultaneous and direct determination of some major (S, Cl, K, Na), minor (P, Fe) and trace (Ca, Cu, Zn) elements in blood, after its deposition onto clinical filter papers, thus giving rise to DBS. For quantification purposes the best strategy was to use matrix-matched blood samples of known analyte concentrations. The accuracy and precision of the method were evaluated by analysis of a blood reference material (Seronorm™ trace elements whole blood L3). Quantitative results were obtained for the determination of P, S, Cl, K and Fe, and limits of detection for these elements were adequate, taking into account their typical concentrations in real blood samples. Determination of Na, Ca, Cu and Zn was hampered by the occurrence of high sample support (Na, Ca) and instrumental blanks (Cu, Zn). Therefore, the quantitative determination of these elements at the levels expected in blood samples was not feasible. The methodology developed was applied to the analysis of several blood samples and the results obtained were compared with those reported by standard techniques. Overall, the performance of the method developed is promising and it could be used to determine the aforementioned elements in blood samples in a simple, fast and economic way. Furthermore, its non-destructive nature enables further analyses by means of complementary techniques to be carried out.

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

Karayigit, A.I.; Bulut, Y.; Karayigit, G.

A total of 48 samples, feed coals (FCs), fly ashes (FAs) and bottom ashes (BAs), which were systematically collected once a week over an eight-week period from boiler units, B1-4 with 660 MW and B5-6 with 330 MW capacity from Soma power plant, have been evaluated for major and trace elements (Al, Ca, Fe, K, Mg, Mn, Na, Ti, S, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Cs, Ga, Ge, Hf, Hg, Li, Mo, Nb, Ni, P, Pb, Rb, Sb, Sc, Se, Sn, Sr, Ta, Th, Tl, U, V, Y, Zn, Zr, and REEs) to get information onmore » behavior during coal combustion. This study indicates that some elements such as Hg, Bi, Cd, As, Pb, Ge, Tl, Sn, Zn, Sb, B show enrichments in FAs relative to the BAs in both group boiler units. In addition to these, Cs, Lu, Tm, and Ga in Units B1-4 and S in Units B5-6 also have enrichments in FAs. Elements showing enrichments in BAs in both group boiler units are Ta, Mn, Nb. In addition to these, Se, Ca, Mg, Na, Fe in Units B1-4 and Cu in Units B5-6 also have enrichments in BAs. The remaining elements investigated in this study have no clear segregation between FAs and BAs. Mass balance calculations with the two methods show that some elements, S, Ta, Hg, Se, Zn, Na, Ca in Units B1-4, and Hg, S, Ta, Se, P in Units B5-6, have volatile behavior during coal combustion in the Soma power plant. This study also implies that some elements, Sb and Tb in Units B1-4 and Sb in Units B5-6, have relatively high retention effects in the combustion residues from the Soma power plant.« less

An evaluation of different soil washing solutions for remediating arsenic-contaminated soils.

PubMed

Wang, Yiwen; Ma, Fujun; Zhang, Qian; Peng, Changsheng; Wu, Bin; Li, Fasheng; Gu, Qingbao

2017-04-01

Soil washing is a promising way to remediate arsenic-contaminated soils. Most research has mostly focused on seeking efficient extractants for removing arsenic, but not concerned with any changes in soil properties when using this technique. In this study, the removal of arsenic from a heavily contaminated soil employing different washing solutions including H 3 PO 4 , NaOH and dithionite in EDTA was conducted. Subsequently, the changes in soil physicochemical properties and phytotoxicity of each washing technique were evaluated. After washing with 2 M H 3 PO 4 , 2 M NaOH or 0.1 M dithionite in 0.1 M EDTA, the soil samples' arsenic content met the clean-up levels stipulated in China's environmental regulations. H 3 PO 4 washing decreased soil pH, Ca, Mg, Al, Fe, and Mn concentrations but increased TN and TP contents. NaOH washing increased soil pH but decreased soil TOC, TN and TP contents. Dithionite in EDTA washing reduced soil TOC, Ca, Mg, Al, Fe, Mn and TP contents. A drastic color change was observed when the soil sample was washed with H 3 PO 4 or 0.1 M dithionite in 0.1 M EDTA. After adjusting the soil pH to neutral, wheat planted in the soil sample washed by NaOH evidenced the best growth of all three treated soil samples. These results will help with selecting the best washing solution when remediating arsenic-contaminated soils in future engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Physicochemical characteristics of ambient particles settling upon leaf surfaces of urban plants in Beijing.

PubMed

Wang, Lei; Liu, Lian-you; Gao, Shang-yu; Hasi, Eerdun; Wang, Zhi

2006-01-01

Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chinensis, Sophora japonica, A ilanthus altissima, Syringa oblata and Prunus persica had larger densities of particles among the tall species. Due to resuspension of road dust, the densities of particles of Euonymus japonicus and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM, (particulate matter less than 10 microm in aerodynamic diameter; 98.4%) and PM25 (particulate matter less than 2.5 microm in aerodynamic diameter; 64.2%) which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si, Al, Mg, Na, Fe, S, Cl and minerals with higher content were SiO2, CaCO3, CaMg(CO3)2, NaCI and 2CaSO4 x H20, SiO2. CaCO3 and CaMg(CO3)2 mainly came from resuspension of road dust. 2CaSO4 x H20 was produced by the reaction between CaCO3 derived from earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.

[Analysis of effects of salt stress on absorption and accumulation of mineral elements in Elymus spp. using atomic absorption spectrophotometer].

PubMed

Jia, Ya-xiong; Sun, Lei; He, Feng; Wan, Li-qiang; Yuan, Qing-hua; Li, Xiang-lin

2008-12-01

Salinization contributes significantly to soil degradation and the growth and survival of plants. A high level of salts imposes both ionic and osmotic stresses on plants, resulting in an excessive accumulation of sodium (Na) in plant tissues. Na toxicity disrupts the uptake of soil nutrients. Plant uptake and absorption of macro-elements under salt stress have been studied in plants, but there is little literature addressing the effect of salt stress on plant accumulation and absorption of micro-elements. Species in Elymus genus are among the most important forage plants on high-salinity soils in China An experiment was conducted to study the effect of salt stress on accumulation and absorption of both macro- and micro-elements by wild plants of Elymus genus. Plant samples taken from two populations with different salt tolerance were tested and the level of 4 macro-elements, namely Na, K, Ca and Mg, and 4 micro-elements, namely Cu, Fe, Mn, Zn was determined using atomic absorption spectrophotometer. The relationship between the selection of elements in the process of absorption and accumulation and salt tolerance was also analyzed. The results showed that the level of Na in root and leaf tissues increased with increasing salt stress. The level of Na in leaf tissue of plants with high salt tolerance (HS) was significantly higher than that in plants with low salt tolerance (P<0.05). The level of K and Ca decreased in response to increasing salt stress, while that in HS was higher than in LS. The level of Fe and Zn in the tissues of both roots and leaves increased. No significant difference was detected between HS and LS samples in the level of Cu in root tissues, while that of Cu in leaf tissue of both samples increased. The level of Mn decreased with increasing salt stress, but was higher in HS than in LS. Fe and Zn in roots and leaves of HS were lower than in those of LS.

Coupled S and Sr isotope evidences for elevated arsenic concentrations in groundwater from the world's largest antimony mine, Central China

NASA Astrophysics Data System (ADS)

Wen, Bing; Zhou, Aiguo; Zhou, Jianwei; Liu, Cunfu; Huang, Yuliu; Li, Ligang

2018-02-01

The Xikuangshan(XKS) mine, the world's largest antimony mine, was chosen for a detailed arsenic hydrogeochemical study because of the elevated arsenic in bedrock aquifers used by local residents. Hydrochemical data, δ34S values of dissolved SO42- and 87Sr/86Sr ratios have been analyzed to identify the predominant geochemical processes that control the arsenic mobilization within the aquifers. Groundwater samples can be divided into three major types: low arsenic groundwater (0-50 μg/L), high arsenic groundwater (50-1000 μg/L) and anomalous high arsenic groundwater (>1000 μg/L). Arsenic occurs under oxidizing conditions at the XKS Sb mine as the HAsO42- anion. The Ca/Na ratio correlates significantly with HCO3-/Na and Sr/Na ratios, indicating that carbonate dissolution and silicate weathering are the dominant processes controlling groundwater hydrochemistry. The δ34S values of the groundwater indicate that dissolved SO42- in groundwater is mainly sourced from the oxidation of sulfide minerals, and elevated As concentrations in groundwater are influenced by the mixing of mine water and surface water. Furthermore, the δ34S values are not correlated with dissolved As concentrations and Fe concentrations, suggesting that the reduction dissolution of Fe(III) hydroxides is not the dominant process controlling As mobilization. The 87Sr/86Sr ratios imply that elevated As concentrations in groundwater are primarily derived from the interaction with the stibnite and silicified limestone. More specifically, the excess-Na ion, the feature of Ca/Na ratio, and the spatial association of elevated As concentrations in groundwater collectively suggest that high and anomalous high arsenic groundwater are associated with smelting slags and, in particular, the arsenic alkali residue. In general, the hydrochemistry analysis, especially the S and Sr isotope evidences elucidate that elevated As concentrations and As mobilization are influenced by several geochemical processes, including: (1) bedrock weathering; (2) oxidation of arsenopyrite and the dominant sulfides in the ores; (3) mixing of mine drainage and surface water; (4) leaching of the arsenic alkali residue; and (5) sorption-desorption from Fe/Mn oxides/hydroxides.

Study of groundwater arsenic pollution in Lanyang Plain using multivariate statistical analysis

NASA Astrophysics Data System (ADS)

chan, S.

2013-12-01

The study area, Lanyang Plain in the eastern Taiwan, has highly developed agriculture and aquaculture, which consume over 70% of the water supplies. Groundwater is frequently considered as an alternative water source. However, the serious arsenic pollution of groundwater in Lanyan Plain should be well studied to ensure the safety of groundwater usage. In this study, 39 groundwater samples were collected. The results of hydrochemistry demonstrate two major trends in Piper diagram. The major trend with most of groundwater samples is determined with water type between Ca+Mg-HCO3 and Na+K-HCO3. This can be explained with cation exchange reaction. The minor trend is obviously corresponding to seawater intrusion, which has water type of Na+K-Cl, because the localities of these samples are all in the coastal area. The multivariate statistical analysis on hydrochemical data was conducted for further exploration on the mechanism of arsenic contamination. Two major factors can be extracted with factor analysis. The major factor includes Ca, Mg and Sr while the minor factor includes Na, K and As. This reconfirms that cation exchange reaction mainly control the groundwater hydrochemistry in the study area. It is worth to note that arsenic is positively related to Na and K. The result of cluster analysis shows that groundwater samples with high arsenic concentration can be grouped into that with high Na, K and HCO3. This supports that cation exchange would enhance the release of arsenic and exclude the effect of seawater intrusion. In other words, the water-rock reaction time is key to obtain higher arsenic content. In general, the major source of arsenic in sediments include exchangeable, reducible and oxidizable phases, which are adsorbed ions, Fe-Mn oxides and organic matters/pyrite, respectively. However, the results of factor analysis do not show apparent correlation between arsenic and Fe/Mn. This may exclude Fe-Mn oxides as a major source of arsenic. The other sources will be evaluated by more trace elements, such as rare earth elements.

Uniformity and diversity in the composition of mineralizing fluids from hydrothermal vents on the southern Juan de Fuca Ridge.

USGS Publications Warehouse

Philpotts, J.A.; Aruscavage, P. J.; Von Damm, Karen L.

1987-01-01

Abundances of Li, Na, K, Rb, Ca, Sr, Ba, Mn, Fe, Zn, and Si have been determined in fluid samples from 7 vents located in three areas on the southern Juan de Fuca Ridge. The hydrothermal component estimated from the Mg contents of the samples ranges from 7% to 76%. Concentrations of Fe and Si, among other elements, in acid-stabilized solutions appear to be generally representative of the parental hydrothermal fluids, but some Zn determinations and most Ba values appear to be too low.-from Authors

Enhanced activity of Au-Fe/C anodic electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

NASA Astrophysics Data System (ADS)

Yi, Lanhua; Wei, Wei; Zhao, Caixian; Tian, Li; Liu, Jing; Wang, Xianyou

2015-07-01

Carbon supported Au-Fe bimetallic nanocatalysts (Au-Fe/C) are facilely prepared via a modified NaBH4 reduction method in aqueous solution at room temperature, and used as the anode electrocatalyst of direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the Au-Fe/C electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), rotating disc electrode (RDE) voltammetry, chronoamperometry (CA), chronopotentiometry (CP), and fuel cell test. The results show that Au-Fe/C catalysts display higher catalytic activity for the direct electrooxidation of BH4- than carbon supported pure Au nanocatalyst (Au/C), especially Au50Fe50/C catalyst presents the highest catalytic activity among all as-prepared catalysts. Besides, the single DBHFC with Au50Fe50/C anode and Au/C cathode obtains the maximum power density as high as 34.9 mW cm-2 at 25 °C.

Mercury's Magma Ocean

NASA Astrophysics Data System (ADS)

Parman, S. W.; Parmentier, E. M.; Wang, S.

2016-12-01

The crystallization of Mercury's magma ocean (MMO) would follow a significantly different path than the terrestrial or lunar magma ocean. Evidence from the MESSENGER mission [1] indicates that Mercury's interior has an oxygen fugacity (fO2) orders of magnitude lower any other terrestrial planet (3-8 log units below the iron-wustite buffer = IW-3 to IW-8; [2]). At these conditions, silicate melts and minerals have negligible Fe contents. All Fe is present in sulfides or metal. Thus, the build up of Fe in the last dregs of the lunar magma ocean, that is so important to its evolution, would not happen in the MMO. There would be no overturn or plagioclase flotation crust. Sulfur solubility in silicate melts increases dramatically at low fO2, from 1 wt% at IW-3 to 8wt% at IW-8 [3]. Thus it is possible, perhaps probable, that km-thick layers of sulfide formed during MMO crystallization. Some of the sulfides (e.g. CaS) have high partition coefficients for trace elements and so could control the spatial distribution of radioactive heat producing elements such as U, Th and K. This in turn would have first order effects on the thermal and chemical evolution of the planet. The distribution of the sulfide layers depend upon the density of the sulfides that form in the MMO. At such low fO2, S forms compounds with a range of elements not typical for other planets: Ca, Mg, Na, K. The densities of these sulfides vary widely, with Mg and Ca-rich sulfides being more dense than estimated MMO densities, and Na and K-rich sulfides being less dense than the MMO. Thus sulfide sinking and floating may produce substantial chemical layering on Mercury, potentially including an Mg-Ca rich deep layer and a Na-K rich shallow layer or possibly floatation crust. The total amount of S in the MMO depends on the fO2 and the bulk S content of Mercury, both of which are poorly constrained. In the most extreme case, if the MMO had an fO2of IW-8 and was sulfide saturated from the start, a total equivalent layer of sulfide up to 50 km could form (Figure 1). [1] Nittler et al (2011) Science 333: 847-1850., [2] Zolotov et al (2013), JGR 118: 138-146. [3] Berthet et al (2009) GCA 73: 6402-6420.

Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing

NASA Astrophysics Data System (ADS)

Tan, Jihua; Duan, Jingchun; Zhen, Naijia; He, Kebin; Hao, Jiming

2016-01-01

The abundance, behavior, and source of chemical species in size-fractionated atmospheric particle were studied with a 13-stage low pressure impactor (ELPI) during high polluted winter episode in Beijing. Thirty three elements (Al, Ca, Fe, K, Mg, Na, Si, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Sr, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, and Pb) and eight water soluble ions (Cl-, NO3-, SO42 -, NH4+, Na+, K+, Ca2 +, and Mg2 +) were determined by ICP/MS and IC, respectively. The size distribution of TC (OC + EC) was reconstructed. Averagely, 51.5 ± 5.3% and 74.1 ± 3.7% of the total aerosol mass was distributed in the sub-micron (PM1) and fine particle (PM2.5), respectively. A significant shift to larger fractions during heavy pollution episode was observed for aerosol mass, NH4+, SO42 -, NO3-, K, Fe, Cu, Zn, Cd, and Pb. The mass size distributions of NH4+, SO42 -, NO3-, and K were dominated by accumulation mode. Size distributions of elements were classified into four main types: (I) elements were enriched within the accumulation mode (< 1 μm, Ge, Se, Ag, Sn, Sb, Cs, Hg, Ti, and Pb); (II) those mass (K, Cr, Mn, Cu, Zn, As, Mo, and Cd) was resided mainly within the accumulation mode, ranged from 1 to 2 μm; (III) Na, V, Co, Ni, and Ga were distributed among fine, intermediate, and coarse modes; and (IV) those which were mainly found within particles larger than 2.7 μm (Al, Mg, Si, Ca, Sc, Tl, Fe, Sr, Zr, and Ba). [H+]cor showed an accumulation mode at 600-700 nm and the role of Ca2 + should be fully considered in the estimation of acidity. The acidity in accumulation mode particles suggested that generally gaseous NH3 was not enough to neutralize sulfate completely. PMF method was applied for source apportionment of elements combined with water soluble ions. Dust, vehicle, aged coal combustion, and sea salt were identified, and the size resolved source apportionments were discussed. Aged coal combustion was the important source of fine particles and dust contributed most to coarse particle.

Singular value decomposition approach to the yttrium occurrence in mineral maps of rare earth element ores using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Romppanen, Sari; Häkkänen, Heikki; Kaski, Saara

2017-08-01

Laser-induced breakdown spectroscopy (LIBS) has been used in analysis of rare earth element (REE) ores from the geological formation of Norra Kärr Alkaline Complex in southern Sweden. Yttrium has been detected in eudialyte (Na15 Ca6(Fe,Mn)3 Zr3Si(Si25O73)(O,OH,H2O)3 (OH,Cl)2) and catapleiite (Ca/Na2ZrSi3O9·2H2O). Singular value decomposition (SVD) has been employed in classification of the minerals in the rock samples and maps representing the mineralogy in the sampled area have been constructed. Based on the SVD classification the percentage of the yttrium-bearing ore minerals can be calculated even in fine-grained rock samples.

Synthesis of the new compound CaFe(CO 3) 2 and experimental constraints on the (Ca,Fe)CO 3 join

NASA Astrophysics Data System (ADS)

Davidson, Paula M.; Symmes, Gregory H.; Cohen, Barbara A.; Reeder, Richard J.; Lindsley, Donald H.

1993-12-01

Synthesis of the new (disordered) compound CaFe(CO 3) 2 has been achieved with the use of Fe-substituted CaCO 3(Cc ss) + Ca-substituted FeCO 3(Sid ss) as starting materials, and high CO 2 pressures. High pressure (20-30 kbar) is needed to stabilize FeCO 3 to sufficiently high temperatures for disordered CaFe(CO 3) 2 to form. Experiments provide reversed compositions of coexisting disordered phases in the CaFe join and locate the solvus temperature for CaFe(C) 3) 2 between 815 and 845°C at 30 kbars. Calculated phase relations predict that the stability of ordered CaFe(CO 3) 2 is limited to T < ˜450°C by the breakdown to Cc ss + Sid ss. A comparison of the unit-cell volume measured for disordered CaFe(CO 3) 2 vs. that estimated for ordered CaFe(CO 3) 2 suggests that increasing pressure stabilizes the disordered phase.

Identification of metal ion binding sites based on amino acid sequences

PubMed Central

Cao, Xiaoyong; Zhang, Xiaojin; Gao, Sujuan; Ding, Changjiang; Feng, Yonge; Bao, Weihua

2017-01-01

The identification of metal ion binding sites is important for protein function annotation and the design of new drug molecules. This study presents an effective method of analyzing and identifying the binding residues of metal ions based solely on sequence information. Ten metal ions were extracted from the BioLip database: Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+ and Co2+. The analysis showed that Zn2+, Cu2+, Fe2+, Fe3+, and Co2+ were sensitive to the conservation of amino acids at binding sites, and promising results can be achieved using the Position Weight Scoring Matrix algorithm, with an accuracy of over 79.9% and a Matthews correlation coefficient of over 0.6. The binding sites of other metals can also be accurately identified using the Support Vector Machine algorithm with multifeature parameters as input. In addition, we found that Ca2+ was insensitive to hydrophobicity and hydrophilicity information and Mn2+ was insensitive to polarization charge information. An online server was constructed based on the framework of the proposed method and is freely available at http://60.31.198.140:8081/metal/HomePage/HomePage.html. PMID:28854211

Identification of metal ion binding sites based on amino acid sequences.

PubMed

Cao, Xiaoyong; Hu, Xiuzhen; Zhang, Xiaojin; Gao, Sujuan; Ding, Changjiang; Feng, Yonge; Bao, Weihua

2017-01-01

The identification of metal ion binding sites is important for protein function annotation and the design of new drug molecules. This study presents an effective method of analyzing and identifying the binding residues of metal ions based solely on sequence information. Ten metal ions were extracted from the BioLip database: Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+ and Co2+. The analysis showed that Zn2+, Cu2+, Fe2+, Fe3+, and Co2+ were sensitive to the conservation of amino acids at binding sites, and promising results can be achieved using the Position Weight Scoring Matrix algorithm, with an accuracy of over 79.9% and a Matthews correlation coefficient of over 0.6. The binding sites of other metals can also be accurately identified using the Support Vector Machine algorithm with multifeature parameters as input. In addition, we found that Ca2+ was insensitive to hydrophobicity and hydrophilicity information and Mn2+ was insensitive to polarization charge information. An online server was constructed based on the framework of the proposed method and is freely available at http://60.31.198.140:8081/metal/HomePage/HomePage.html.

Micro-Raman spectroscopy and μ-XRF in the investigation of ancient glass beads from the archaeological sites, eastern Taiwan

NASA Astrophysics Data System (ADS)

San Liou, Ying; Liu, Yi Chang

2017-04-01

Ancient glass beads with different colors, shapes, and stylistics unearthed from the archaeological sites of eastern Taiwan, dating back to approximately 1850-310 BP, have been investigated. It is generally known that glass bead is alien to invade into Taiwan along with metal ware, glass, agate, etc. since the Metal Age of Taiwan. Nevertheless, souring provenance and trade routes still remain controversial. Micro-Raman spectroscopy and μ-XRF have been applied on fifty-six ancient glass beads to reveal the mineralogical and chemical compositions and to help decipher the raw materials used and souring provenance. Micro-Raman measurements indicate the presence of hematite, zincite, siderite, sphalerite, lead tin yellow type II, quartz, feldspar, anatase, rutite, ankerite, graphite, calcite, etc. Among them, hematite, zincite, siderite, sphalerite, lead tin yellow type II, and rutile were found to be colorants/opacifiers. Moreover, crystalline phases such as lead tin yellow type II (PbSn1-xSixO3), zincite (ZnO), tricalcium diphosphate (Ca2(PO4)2), sphalerite ((Zn, Fe)S) and ankerite (Ca(Fe, Mg, Mn)(CO3)2) were detected in ancient glass beads unearthed from Taiwan for the first time. The chemical results obtained by μXRF show SiO2, Al2O3, Na2O, K2O, MgO, CaO, and PbO as the most abundant oxides. Na2O, K2O, Al2O3, MgO, and PbO could be the main/minor fluxes and colorants. In general, results of mineralogical and chemical analyses are compatible. According to chemical results, ancient glass beads can be classified as mineral soda alumina glass (m-Na-Al glass), soda plant ash glass (v-Na-Ca glass), lead silicate glass, and some less well known types. Mineral soda alumina and soda plant ash glass beads, as well as lead silicate glass beads are generally believed to be the distinct phases of production and exchange in Southeast Asia and China, respectively. In terms of chronology of glass bead, beads excavated from sites of 1850-930 BP are mineral soda alumina glass (m-Na-Al glass) and soda plant ash glass (v-Na-Ca glass). On the other hand, beads from sites of <930 BP are belonging to lead silicate glass. It is indicated that the souring provenance of ancient beads of eastern Taiwan is probably a multiple sources, i.e., in earlier time, glass beads were brought into Taiwan through the maritime exchange and/or trade activities between Taiwan and Southeast Asia; at the later period, lead silicate glass beads were imported from China. However, some mineral soda alumina and soda plant ash glass beads were found in a later period, it might be attributed to glass beads reuse or trade route between Taiwan and Southeast Asia is successive since ca. 1850 BP.

Retention Mechanisms of Citric Acid in Ternary Kaolinite-Fe(III)-Citrate Acid Systems Using Fe K-edge EXAFS and L3,2-edge XANES Spectroscopy

PubMed Central

Yang, Jianjun; Wang, Jian; Pan, Weinan; Regier, Tom; Hu, Yongfeng; Rumpel, Cornelia; Bolan, Nanthi; Sparks, Donald

2016-01-01

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorption and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. These findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils. PMID:27212680

Retention mechanisms of citric acid in ternary kaolinite-Fe(III)-citrate acid systems using Fe K-edge EXAFS and L 3,2-edge XANES spectroscopy

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

Yang, Jianjun; Wang, Jian; Pan, Weinan

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L- 3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorptionmore » and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤ 0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. In conclusion, these findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils.« less

Retention mechanisms of citric acid in ternary kaolinite-Fe(III)-citrate acid systems using Fe K-edge EXAFS and L 3,2-edge XANES spectroscopy

DOE PAGES

Yang, Jianjun; Wang, Jian; Pan, Weinan; ...

2016-05-23

Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L- 3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorptionmore » and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤ 0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. In conclusion, these findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils.« less

CHEMICAL ABUNDANCES OF MEMBER STARS IN THE OPEN CLUSTER NGC 2632 (PRAESEPE)

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

Yang, X. L.; Chen, Y. Q.; Zhao, G.

2015-11-15

Based on high-resolution, high signal-to-noise ratio spectra, we present abundances of 17 elements (Fe, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Co, Ni, Y, Zr, Ba, La) for six stars (one Am star, one F dwarf star, and four GK giant stars) and radial velocities for 18 proper-motion selected member stars in the open cluster NGC 2632. In the Am star, s-process elements Y and Ba are clearly overabundant, which may be considered as an indicator of a peculiar Am star. The average [Fe/H] is 0.16 ± 0.06 from four GK giant member stars, which is similarmore » to that of solar-type stars in the literature. As compared with dwarf stars, significant overabundances are found for Na, Mg, and Ba elements in our giant stars, which can be explained by the evolutionary effect. We also detect a star-to-star scatter of [Na/Fe] ratios among four giants which locate approximately at the same position in the CMD. Finally, we perform an analysis on the possible connection between the abundance and spatial structure of NGC 2632, but we find no inhomogeneous abundance among different clumps of stars in this cluster based on our limited sample.« less

Redox equilibria of multivalent ions in silicate glasses

NASA Technical Reports Server (NTRS)

Lauer, H. V., Jr.; Morris, R. V.

1977-01-01

Experimental studies were made on the compositional dependence of the redox equilibrium of Eu in synthetic silicate liquids, together with an empirical model describing the observed compositional dependence. Electron paramagnetic resonance (EPR) was used to measure the concentration ratio of Eu(2+) to Eu(3+) in various glasses formed by rapidly quenching silicate liquids. The compositional field studied comprised mixtures of SiO2, TiO2, Al2O3, CaO, MgO, and Na2O. The proposed model describes the Eu(2+)/Eu(3+) ratio over the entire compositional field in terms of parameters easily related to each glass composition. The general applicability and utility of the model is further demonstrated by its application to the Fe(2+)-Fe(3+), Ce(3+)-Ce(4+), and Cr(3+)-Cr(6+) redox reactions in binary alkali oxide silicate glasses of Li, Na, and K.

[Analysis of the mineral elements of Lactuca sativa under the condition of different spectral components].

PubMed

Chen, Xiao-Li; Guo, Wen-Zhong; Xue, Xu-Zhang; Wang, Li-Chun; Li, Liang; Chen, Fei

2013-08-01

Mineral elements absorption and content of Lactuca sativa under different spectral component conditions were studied by ICP-AES technology. The results showed that: (1) For Lactuca sativa, the average proportion for Ca : Mg : K : Na : P was 5.5 : 2.5 : 2.3 : 1.5 : 1.0, the average proportion for Fe : Mn : Zn : Cu : B was 25.9 : 5.9 : 2.8 : 1.1 : 1.0; (2) The absorptions for K, P, Ca, Mg and B are the largest under the LED treatment R/B = 1 : 2.75, red light from fluorescent lamps and LED can both promote the absorptions of Fe and Cu; (3)The LED treatments exhibiting relatively higher content of mineral elements are R/B = 1 : 2.75 and R/W = 1 : 1 while higher dry matter accumulations are R/B = 1 : 2.75 and B/W = 1 : 1.

Biomineral microstructures in ferromanganese nodules: evidence of the biological and abiogenous origin

NASA Astrophysics Data System (ADS)

Lysyuk, G. N.

2011-10-01

Manganese oxides, which are widespread and of great practical importance, are formed and transformed by the active role of microorganisms. Manganese aggregates occur as both crystallized varieties and disordered fine-grained phases with significant ore grade and up to 50-60 vol % of X-ray amorphous components. X-ray amorphous nanosizedMn oxides in Fe-Mn nodules from the Pacific Ocean floor were examined from the standpoint of their biogenic origin. SEM examination showed abundant mineralized biofilms on the studied samples. The chemical composition of bacterial mass is as follows (wt %): 28.34 MnO, 17.14 Fe2O3, 7.11 SiO2, 2.41 CaO, 17.90 TiO2, 1.74Na2O,1.73 A12O3,1.30 MgO, 1.25P2O5,1.25 SO3,0.68 CoO, 0.54 CuO, 0.53 NiO, and 0.50 K2O. The chemical composition of fossilized cyanobacterial mats within the interlayer space of nodules is as follows (wt %): 48.35 MnO, 6.23 Fe2O3, 8.76 MgO, 5.05 A12O3, 4.45 SiO2, 3.63 NiO, 2.30 Na2O, 2.19 CuO, 1.31 CaO, and 0.68 K2O is direct evidence for participation of bacteria in Mn oxide formation. This phase consists of mineralized glycocalix consisting of nanosized flakes of todorokite. Native metals (Cu, Fe, and Zn) as inclusions 10-20 μm in size were identified in ferromanganese nodules as well. The formation of native metals can be explained by their crystallization at highly reducing conditions maintained by organic matter.

Evaluation of sol-gel based magnetic 45S5 bioglass and bioglass-ceramics containing iron oxide.

PubMed

Shankhwar, Nisha; Srinivasan, A

2016-05-01

Multicomponent oxide powders with nominal compositions of (45-x)·SiO2·24.5CaO·24.5Na2O·6P2O5xFe2O3 (in wt.%) were prepared by a modified sol-gel procedure. X-ray diffraction (XRD) patterns and high resolution transmission electron microscope images of the sol-gel products show fully amorphous structure for Fe2O3 substitutions up to 2 wt.%. Sol-gel derived 43SiO2·24.5CaO·24.5Na2O·6P2O5·2Fe2O3 glass (or bioglass 45S5 with SiO2 substituted with 2 wt.% Fe2O3), exhibited magnetic behavior with a coercive field of 21 Oe, hysteresis loop area of 33.25 erg/g and saturation magnetization of 0.66 emu/g at an applied field of 15 kOe at room temperature. XRD pattern of this glass annealed at 850 °C for 1h revealed the formation of a glass-ceramic containing sodium calcium silicate and magnetite phases in nanocrystalline form. Temperature dependent magnetization and room temperature electron spin resonance data have been used to obtain information on the magnetic phase and distribution of iron ions in the sol-gel glass and glass-ceramic samples. Sol-gel derived glass and glass-ceramic exhibit in-vitro bioactivity by forming a hydroxyapatite surface layer under simulated physiological conditions and their bio-response is superior to their melt quenched bulk counterparts. This new form of magnetic bioglass and bioglass ceramics opens up new and more effective biomedical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

KINETyS II: Constraints on spatial variations of the stellar initial mass function from K-band spectroscopy

NASA Astrophysics Data System (ADS)

Alton, P. D.; Smith, R. J.; Lucey, J. R.

2018-05-01

We investigate the spatially resolved stellar populations of a sample of seven nearby massive Early-type galaxies (ETGs), using optical and near infrared data, including K-band spectroscopy. This data offers good prospects for mitigating the uncertainties inherent in stellar population modelling by making a wide variety of strong spectroscopic features available. We report new VLT-KMOS measurements of the average empirical radial gradients out to the effective radius in the strengths of the Ca I 1.98 μm and 2.26 μm features, the Na I 2.21 μm line, and the CO 2.30 μm bandhead. Following previous work, which has indicated an excess of dwarf stars in the cores of massive ETGs, we pay specific attention to radial variations in the stellar initial mass function (IMF) as well as modelling the chemical abundance patterns and stellar population ages in our sample. Using state-of-the-art stellar population models we infer an [Fe/H] gradient of -0.16±0.05 per dex in fractional radius and an average [Na/Fe] gradient of -0.35±0.09. We find a large but radially-constant enhancement to [Mg/Fe] of ˜ 0.4 and a much lower [Ca/Fe] enhancement of ˜ 0.1. Finally, we find no significant IMF radial gradient in our sample on average and find that most galaxies in our sample are consistent with having a Milky Way-like IMF, or at most a modestly bottom heavy IMF (e.g. less dwarf enriched than a single power law IMF with the Salpeter slope).

Discovery of Ahrensite γ-Fe2SiO4 and Tissintite (Ca,Na,[])AlSi2O6, Two New Shock-induced Minerals from the Tissint Martian Meteorite: a Nanomineralogy Investigation

NASA Astrophysics Data System (ADS)

Ma, C.; Tschauner, O. D.; Liu, Y.; Sinogeikin, S. V.; Zhuravlev, K. K.; Prakapenka, V.; Dera, P. K.; Taylor, L. A.

2013-12-01

The recent Martian meteorite fall, Tissint, is a fresh olivine-phyric shergottite, with strong shock features. During our nano-mineralogy investigation of the Tissint meteorite with a combined analytical scanning electron microscope and synchrotron diffraction approach, two new shock-induced minerals have been discovered; these provide new insights into understanding shock conditions and impact processes on Mars. Ahrensite (IMA 2013-028), the Fe-analogue (γ-Fe2SiO4) of ringwoodite, is a new high-pressure mineral identified in Tissint. Both ahrensite and ringwoodite occur in Tissint as fine-grained polycrystalline aggregates in the rims of olivines around some shock-melt pockets. The morphology and texture of these silicate-spinels suggest formation by a solid-state transformation from Fe-rich olivine. Associated with the ahrensite and ringwoodite, inside melt pockets, often resides a thin layer of vitrified silicate-perovskite and magnesio-wüstite or wüstite. Such transitions represent a unique pressure and temperature gradient. Tissintite (IMA 2013-027), (Ca,Na,[])AlSi2O6 with the C2/c clinopyroxene structure, is a new jadeite-like mineral in Tissint. It appears as fine-grained aggregates within plagioclase glass, inside many shock-melt pockets. Both ahrensite and tissintite are high-pressure minerals formed by shock during the impact event(s) on Mars that excavated and ejected the rock off Mars. We will discuss the path of structure analysis for both new-mineral cases. Such novel methodology be utilized for many cases of mineralogical phase identification or structure analysis; this demonstrates how nano-mineralogy can be addressed and how it may play a unique role in meteorite and Mars rock research, in general.

Properties of ceramics prepared using dry discharged waste to energy bottom ash dust.

PubMed

Bourtsalas, Athanasios; Vandeperre, Luc; Grimes, Sue; Themelis, Nicolas; Koralewska, Ralf; Cheeseman, Chris

2015-09-01

The fine dust of incinerator bottom ash generated from dry discharge systems can be transformed into an inert material suitable for the production of hard, dense ceramics. Processing involves the addition of glass, ball milling and calcining to remove volatile components from the incinerator bottom ash. This transforms the major crystalline phases present in fine incinerator bottom ash dust from quartz (SiO(2)), calcite (CaCO(3)), gehlenite (Ca(2)Al(2)SiO(7)) and hematite (Fe(2)O(3)), to the pyroxene group minerals diopside (CaMgSi(2)O(6)), clinoenstatite (MgSi(2)O(6)), wollastonite (CaSiO(3)) together with some albite (NaAlSi(3)O(8)) and andradite (Ca(3)Fe(2)Si(3)O(12)). Processed powders show minimal leaching and can be pressed and sintered to form dense (>2.5 g cm(-3)), hard ceramics that exhibit low firing shrinkage (<7%) and zero water absorption. The research demonstrates the potential to beneficially up-cycle the fine incinerator bottom ash dust from dry discharge technology into a raw material suitable for the production of ceramic tiles that have potential for use in a range of industrial applications. © The Author(s) 2015.

Using Meteoric Ablation to Constrain Vertical Transport in the Upper Mesosphere

NASA Astrophysics Data System (ADS)

Plane, J. M. C.; Carrillo-Sánchez, J. D.; Nesvorny, D.; Pokorný, P.; Janches, D.

2016-12-01

Meteoric ablation injects a variety of metals into the upper mesosphere and lower thermosphere, giving rise to layers of metal atoms centered around 90 km. The Na, Fe, K and Ca atom densities are measured accurately using resonance lidars. Since the reaction kinetics of many of the chemical reactions which produce these layers have now been studied in the laboratory, chemistry modules for each of the metals have been developed with a reasonable degree of confidence. When these modules are put into a global high-top model such as NCAR's Whole Atmosphere Community Climate Model (WACCM), a major problem emerges: the injection flux of each of the metals, termed the Meteoric Input Function (MIF), has to be reduced substantially in order to model the observed metal atom densities. For instance, the Na and Fe MIFs need to be reduced by factors of 8 and 14, respectively, compared with the MIFs determined from the lidar-measured vertical fluxes of Na and Fe atoms. The accumulation of meteoric smoke particles in polar ice cores also indicates that the meteoric ablation flux is significantly larger that can be handled in models where vertical transport is solely due to eddy diffusional mixing. Here we derive new Na and Fe MIFs by determining the relative contributions of the known dust sources in the near-Earth environment: Jupiter Family Comets (JFCs), the main asteroid belt, Halley Type comets, and Oort Cloud comets. The mass/velocity/radiant distributions of these cosmic dust populations are Monte Carlo sampled and the elemental ablation rates calculated with the Leeds Chemical Ablation Model. The contribution of each dust source in the Earth's atmosphere is then determined by fitting the measured cosmic spherule accretion rate at the South Pole, and the measured vertical Na and Fe fluxes above 86 km. We conclude that JFCs contribute either 85% or 93% to the total incoming mass, depending on whether infra-red observations of the Zodiacal Dust Cloud by the IRAS or Planck satellites, respectively, are used. The global ablated meteoric mass is then 6 tonnes per day, of which 0.2 tonnes is Na and 2.1 tonnes is Fe. We show that these large fluxes can be accommodated by including wave-driven chemical transport along with eddy diffusion in a 1-D model.

Bioaugmentation in growing plants for lunar bases

NASA Astrophysics Data System (ADS)

Zaets, I.; Burlak, O.; Rogutskyy, I.; Vasilenko, A.; Mytrokhyn, O.; Lukashov, D.; Foing, B.; Kozyrovska, N.

2011-03-01

Microorganisms may be a key element in a precursory scenario of growing pioneer plants for extraterrestrial exploration. They can be used for plant inoculation to leach nutritional elements from regolith, to alleviate lunar stressors, as well as to decompose both lunar rocks and the plant straw in order to form a protosoil. Bioleaching capacities of both French marigold (Tagetes patula L.) and the associated bacteria in contact with a lunar rock simulant (terrestrial anorthosite) were examined using the model plant-bacteria microcosms under controlled conditions. Marigold accumulated K, Na, Fe, Zn, Ni, and Cr at higher concentrations in anorthosite compared to the podzol soil. Plants inoculated with the consortium of well-defined species of bacteria accumulated higher levels of K, Mg, and Mn, but lower levels of Ni, Cr, Zn, Na, Ca, Fe, which exist at higher levels in anorthosite. Bacteria also affected the Са/Mg and Fe/Mn ratios in the biomass of marigold grown on anorthosite. Despite their growth retardation, the inoculated plants had 15% higher weight on anorthosite than noninoculated plants. The data suggest that the bacteria supplied basic macro-and microelements to the model plant.

[Study on composite stabilization of arsenic (As) contaminated soil].

PubMed

Wang, Hao; Pan, Li-xiang; Zhang, Xiang-yu; Li, Meng; Song, Bao-hua

2013-09-01

Since the contaminated soil may contain various kinds of heavy metals, use of single chemical reagent leads to poor remediation and high cost. In this study, soil containing As, Zn, Cd was sampled, and different reagents were selected to carry out the rapid stabilization of contaminated soil. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of heavy metals and the results indicated that calcium-containing, sulphur-containing and iron-containing reagents had good performance in reducing the metal mobility. The stabilization efficiency of the six reagents tested ranked in the order of CaO > Na2S > organic sulfur > Chitosan > FeSO4 > (C2H5)2NCS2Na. Two types of reagents (six reagents) were combined based on the target properties of different reagents and the stabilization efficiency was evaluated and analyzed. The results indicated that the composite reagents had higher stabilization efficiency: the efficiency of 3% FeSO4 + 5% CaO was 81.7%, 97.2% and 68.2% for As, Cd and Zn, respectively, and the efficiency of 3% CaO + 5% organic sulfur was 76.6%, 95.7% and 93.8% for these three metals, respectively. Speciation analysis was carried out in this study and the results suggested that it was the change of metals from the exchangeable state to the reduction (for inorganic reagent) or oxidation state (for organic reagent) that caused the soil stabilization and the degree of change determined the stabilization efficiency.

Coarse particle (PM10-2.5) source profiles for emissions from domestic cooking and industrial process in Central India.

PubMed

Bano, Shahina; Pervez, Shamsh; Chow, Judith C; Matawle, Jeevan Lal; Watson, John G; Sahu, Rakesh Kumar; Srivastava, Anjali; Tiwari, Suresh; Pervez, Yasmeen Fatima; Deb, Manas Kanti

2018-06-15

To develop coarse particle (PM 10-2.5 , 2.5 to 10μm) chemical source profiles, real-world source sampling from four domestic cooking and seven industrial processing facilities were carried out in "Raipur-Bhilai" of Central India. Collected samples were analysed for 32 chemical species including 21 elements (Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, S, Sb, Se, V, and Zn) by atomic absorption spectrophotometry (AAS), 8 water-soluble ions (Na + , K + , Mg 2+ , Ca 2+ , Cl - , F - , NO 3 - , and SO 4 2- ) by ion chromatography, ammonium (NH 4 + ) by spectrophotometry, and carbonaceous fractions (OC and EC) by thermal/optical transmittance. The carbonaceous fractions were most abundant fraction in household fuel and municipal solid waste combustion emissions while elemental species were more abundant in industrial emissions. Most of the elemental species were enriched in PM 2.5 (<2.5μm) size fraction as compared to the PM 10-2.5 fraction. Abundant Ca (13-28%) was found in steel-rolling mill (SRM) and cement production industry (CPI) emissions, with abundant Fe (14-32%) in ferro-manganese (FEMNI), steel production industry (SPI), and electric-arc welding emissions. High coefficients of divergence (COD) values (0.46 to 0.88) among the profiles indicate their differences. These region-specific source profiles are more relevant to source apportionment studies in India than profiles measured elsewhere. Copyright © 2018. Published by Elsevier B.V.

Electrochemical Synthesis of Core-Shell-Structured NbC-Fe Composite Powder for Enforcement in Low-Carbon Steel.

PubMed

Li, Hongmei; Song, Qiushi; Xu, Qian; Chen, Ying; Xu, Liang; Man, Tiannan

2017-11-01

An NbC-Fe composite powder was synthesized from an Nb₂O₅/Fe/C mixture by electrochemical reduction and subsequent carbonization in molten CaCl₂-NaCl. The composite has a core-shell structure, in which NbC acts as the cores distributing in the Fe matrix. A strong bonding between NbC and Fe is benefit from the core-shell structure. The sintering and electrochemical reduction processes were investigated to probe the mechanism for the reactions. The results show that NbC particles about several nanometers were embraced by the Fe shell to form a composite about 100 nm in size. This featured structure can feasibly improve the wettability and sinterability of NbC as well as the uniform distribution of the carbide in the cast steel. By adding the composite into steel in the casting process, the grain size of the casted steel was markedly deceased from 1 mm to 500 μm on average, favoring the hardening of the casted steel.

Influence of Climate and Lithology on Soil Phosphorus

NASA Astrophysics Data System (ADS)

Wilson, S. G.; Margenot, A. J.; O'Geen, A. T.; Dahlgren, R. A.

2016-12-01

Climate and lithology are master variables of pedogenesis. We hypothesize that differences in parent material composition will influence the outcome of soil P fractionation, in concert with climate and the relative degree of chemical weathering. Here, we investigate a novel climo-lithosequence to elucidate the influence of lithology and climate on P dynamics. Three climosequences (elevational transects) spanning four climatic zones (Blue-Oak, Ponderosa Pine, White fir and Red fir), and three bedrock lithologies (basalt, andesite and granodiorite) were investigated across the Sierra Nevada and southern Cascades. Replicate soil samples were collected by genetic horizon at twelve sites (4 climate zones x 3 lithologies) and characterized by a modified Hedley P fractionation method to quantify P into operationally defined pools. Initial results from the fractionation of andesite and basalt transects (granodiorite forthcoming) show large climatic and lithologic effects on soil P fractions, suggesting that the distribution of soil P and the trajectory of P transformations are significantly influenced by lithology as well as climate. For example, in the climatic zone of least weathering (Red fir), all soil P fractions showed significant lithologic effects. In contrast, with increased weathering, parent material effects on soil P fractions become progressively muted, so that in the zone of most intense weathering (Ponderosa Pine), soil P fractions such as Ca-Pi (1 M HCl-Pi) and labile-Pi (Resin Pi + NaHCO3-Pi), no longer show an influence from lithology. Additionally, significant climatic effects were noted for labile-Pi, Ca-Pi and Fe/Al-Pi (0.1 M NaOH-Pi). A strong positive correlation was observed between poorly crystalline Fe/Al-(hydr)oxides (oxalate extractable Fe and Al) and Fe/Al-Pi (p<0.0001). Conversely, a strong negative correlation was observed between crystalline Fe-oxides (inferred by citrate-dithionite extractable Fe) and Fe/Al-Pi (p<0.0001). Results suggest that P dynamics in soils are strongly influenced not only by climate and the relative degree of chemical weathering, but also lithology, especially during the early stages of pedogenesis. Therefore, parent material and climate may interact more strongly than previously thought to regulate P biogeochemistry.

Fragipan Horizon Fragmentation in Slaking Experiments with Amendment Materials and Ryegrass Root Tissue Extracts

PubMed Central

Karathanasis, A. D.; Murdock, L. W.; Matocha, C. J.; Grove, J.; Thompson, Y. L.

2014-01-01

Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5–18.8 mm compared to the 44.2–47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress. PMID:25254233

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.)

High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey

NASA Astrophysics Data System (ADS)

Jacobson, Heather R.; Keller, Stefan; Frebel, Anna; Casey, Andrew R.; Asplund, Martin; Bessell, Michael S.; Da Costa, Gary S.; Lind, Karin; Marino, Anna F.; Norris, John E.; Peña, José M.; Schmidt, Brian P.; Tisserand, Patrick; Walsh, Jennifer M.; Yong, David; Yu, Qinsi

2015-07-01

The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the Ca ii K 3933 Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [{Fe}/{{H}}]≤slant -3.0. Nine have [{Fe}/{{H}}]≤slant -3.5, with three at [{Fe}/{{H}}]∼ -4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be “Fe-enhanced,” while another star has an extremely large [Sr/Ba] ratio: \\gt 2. Only one other star is known to have a comparable value. Seven stars are “CEMP-no” stars ([{{C}}/{Fe}]\\gt 0.7, [{Ba}/{Fe}]\\lt 0). 21 stars exhibit mild r-process element enhancements (0.3≤slant [{Eu}/{Fe}]\\lt 1.0), while four stars have [{Eu}/{Fe}]≥slant 1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

Phase transition behavior of (K,Na)NbO3-based high-performance lead-free piezoelectric ceramic composite with different phase compositions depending on Na fraction

NASA Astrophysics Data System (ADS)

Yamada, Hideto; Matsuoka, Takayuki; Yamazaki, Masato; Ohbayashi, Kazushige; Ida, Takashi

2018-01-01

The structures of the main (K1- x Na x )NbO3 perovskite in a high-performance lead-free piezoelectric ceramic composite (K1- x Na x )0.86Ca0.04Li0.02Nb0.85O3-δ-K0.85Ti0.85Nb1.15O5-BaZrO3-MgO-Fe2O3 (x = 0.52 and 0.70) with trace amounts of LiMgFeTiO4 inverse spinel and (Li,K)2(Mg,Fe,Ti,Nb)6O13 layered structure have been investigated by transmission electron microscopy (TEM) and synchrotron powder X-ray diffractometry (XRD) with varying temperatures. The bright-field TEM images have shown tetragonal 90°-domain contrasts at 80 and 40 °C, and the XRD profile has been simulated by adding an average structure of two differently oriented tetragonal structures bound by a 90°-domain wall for the x = 0.52 sample. Aggregates of tilted NbO6 nanodomains have been observed in a high-resolution TEM image, and the crossover of P4mm-Amm2 features from 60 to 20 °C and diffuse 2 × 2 × 2 superlattice reflections of the tilted NbO6 Imm2 structure have been observed in XRD data for the x = 0.70 sample.

Calcium intercalation into layered fluorinated sodium iron phosphate

DOE PAGES

Lipson, Albert L.; Kim, Soojeong; Pan, Baofei; ...

2017-10-09

Here, the energy density and cost of battery systems could be improved by moving to alternative battery chemistries such as Ca-ion. However, in order to switch chemistries many problems need to be solved including the identification of cathode materials with high energy density, and electrolytes that can plate and strip calcium metal. Herein, the feasibility and cycling performance of Ca 2+ intercalation into a desodiated layered Na 2FePO 4F host is described. This is the first demonstration of Ca 2+ intercalation into a polyanionic framework, which implies that other polyanionic framework materials may be active for Ca 2+ intercalation. Althoughmore » substantial effort is still needed to identify a high energy density cathode material, this study and others demonstrate the feasibility of Ca 2+ intercalation into multiple materials making it more probable that such a cathode material can be found.« less

Calcium intercalation into layered fluorinated sodium iron phosphate

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

Lipson, Albert L.; Kim, Soojeong; Pan, Baofei

Here, the energy density and cost of battery systems could be improved by moving to alternative battery chemistries such as Ca-ion. However, in order to switch chemistries many problems need to be solved including the identification of cathode materials with high energy density, and electrolytes that can plate and strip calcium metal. Herein, the feasibility and cycling performance of Ca 2+ intercalation into a desodiated layered Na 2FePO 4F host is described. This is the first demonstration of Ca 2+ intercalation into a polyanionic framework, which implies that other polyanionic framework materials may be active for Ca 2+ intercalation. Althoughmore » substantial effort is still needed to identify a high energy density cathode material, this study and others demonstrate the feasibility of Ca 2+ intercalation into multiple materials making it more probable that such a cathode material can be found.« less

Can we improve the salinity tolerance of genotypes of Taxodium by using varietal and hybrid crosses?

USGS Publications Warehouse

Zhou, Lijing; Creech, David L.; Krauss, Ken W.; Yunlong, Yin; Kulhavy, David L.

2010-01-01

Taxodium distichum (L.) Rich. var. distichum [baldcypress (BC)], Taxodium distichum var. mexicanum Gordon [Montezuma cypress (MC)], and a Taxodium hybrid (\\'Nanjing Beauty\\': BC x MC cross, T302) were evaluated for salt tolerance in 2006 at Nacogdoches, TX. Plants were irrigated weekly with four levels of salinity [0, 1, 3.5, and 6 ppt (0, 17, 60, and 102 mol*m-3)] for 13 weeks and then 0, 2, 7, and 12 ppt (0, 34, 120, and 204 mol*m-3) for another 12 weeks. Salinity treatments did not have a significant effect on growth rate; however, there were significant differences in growth rate among the three genotypes. Genotype T302 produced the greatest wet weight, whereas MC had stronger apical dominance and exhibited the greatest increase in height over the course of study. As expected, sodium (Na) concentration in Taxodium leaves increased as sea salt concentrations increased but did not tilt Na/potassium (K) ratios to stressful disproportions. Of the three genotypes, BC exhibited the highest leaf content of Na, calcium (Ca), sulfur (S), and iron (Fe); MC had the lowest leaf content of Na, Ca, S, and Fe; and T302 was intermediate. The benefits of using a hybrid cross (T302) that maintains greater biomass than BC or MC across a range of salinities must be weighed against the potential additional pruning and training necessary for cutting-grown clones relative to BC and MC propagated from seed and flood tolerance relative to BC. Still, combining the best characteristics of different varieties of T. distichum should facilitate the production of favorable genotypes tolerant to a number of soil physical and chemical property fluctuations for arboricultural operations.

SEM, EDX, Infrared and Raman spectroscopic characterization of the silicate mineral yuksporite

NASA Astrophysics Data System (ADS)

Frost, Ray L.; López, Andrés; Scholz, Ricardo; Theiss, Frederick L.; Romano, Antônio Wilson

2015-02-01

The mineral yuksporite (K,Ba)NaCa2(Si,Ti)4O11(F,OH)ṡH2O has been studied using the combination of SEM with EDX and vibrational spectroscopic techniques of Raman and infrared spectroscopy. Scanning electron microscopy shows a single pure phase with cleavage fragment up to 1.0 mm. Chemical analysis gave Si, Al, K, Na and Ti as the as major elements with small amounts of Mn, Ca, Fe and REE. Raman bands are observed at 808, 871, 930, 954, 980 and 1087 cm-1 and are typical bands for a natural zeolite. Intense Raman bands are observed at 514, 643 and 668 cm-1. A very sharp band is observed at 3668 cm-1 and is attributed to the OH stretching vibration of OH units associated with Si and Ti. Raman bands resolved at 3298, 3460, 3562 and 3628 cm-1 are assigned to water stretching vibrations.

Ion mediated targeting of cells with nanoparticles

NASA Astrophysics Data System (ADS)

Maheshwari, Vivek; Fu, Jinlong

2010-03-01

In eukaryotic cells, Ca^2+ ions are necessary for intracellular signaling, in activity of mitochondria and a variety of other cellular process that have been linked to cell apoptosis, proteins synthesis and cell-cycle regulation. Here we show that Ca^2+ ions, serving as the bio-compatible interface can be used to target Saccharomyces cerevisiae (SaC, baker's yeast), a model eukaryotic cell, with Au nanoparticles (10 nm). The Ca^2+ ions bind to the carboxylic acid groups in the citrate functionalized Au nanoparticles. This transforms the nanoparticles into micron long 1-D branched chain assemblies due to inter-particle dipole-dipole interaction and inter-particle bonding due to the divalent nature of the Ca^2+ ion. A similar transformation is observed with the use of divalent ions Mg^2+, Cd^2+ and Fe^2+. The 1-D assembly aids the interfacing of ion-nanoparticles on the cell by providing multiple contact points. Further monovalent ions such as Na^+ are also effective for the targeting of the cell with nanoparticles. However Na-Au nanoparticles are limited in their deposition as they exist in solution as single particles. The cells remain alive after the deposition process and their vitality is unaffected by the interfacing with ion-nanoparticles.

Crystalline maricite NaFePO4 as a positive electrode material for sodium secondary batteries operating at intermediate temperature

NASA Astrophysics Data System (ADS)

Hwang, Jinkwang; Matsumoto, Kazuhiko; Orikasa, Yuki; Katayama, Misaki; Inada, Yasuhiro; Nohira, Toshiyuki; Hagiwara, Rika

2018-02-01

Maricite NaFePO4 (m-NaFePO4) was investigated as a positive electrode material for intermediate-temperature operation of sodium secondary batteries using ionic liquid electrolytes. Powdered m-NaFePO4 was prepared by a conventional solid-state method at 873 K and subsequently fabricated in two different conditions; one is ball-milled in acetone and the other is re-calcined at 873 K after the ball-milling. Electrochemical properties of the electrodes prepared with the as-synthesized m-NaFePO4, the ball-milled m-NaFePO4, and the re-calcined m-NaFePO4 were investigated in Na[FSA]-[C2C1im][FSA] (C2C1im+ = 1-ethyl-3-methylimidazolium, FSA- = bis(fluorosulfonyl)amide) ionic liquid electrolytes at 298 K and 363 K to assess the effects of temperature and particle size on their electrochemical properties. A reversible charge-discharge capacity of 107 mAh g-1 was achieved with a coulombic efficiency >98% from the 2nd cycle using the ball-milled m-NaFePO4 electrode at a C-rate of 0.1 C and 363 K. Electrochemical impedance spectroscopy using m-NaFePO4/m-NaFePO4 symmetric cells indicated that inactive m-NaFePO4 becomes an active material through ball-milling treatment and elevation of operating temperature. X-ray diffraction analysis of crystalline m-NaFePO4 confirmed the lattice contraction and expansion upon charging and discharging, respectively. These results indicate that the desodiation-sodiation process in m-NaFePO4 is reversible in the intermediate-temperature range.

Perchlorate Removal, Destruction and Field Monitoring Demonstration (Groundwater RemediationPilot-Scale)

DTIC Science & Technology

2008-08-01

Space Administration NDBA N-nitrosodi-n-butylamine NDEA N-nitrosodiethylamine NDMA N-nitrosodimethylamine NDPA N-nitrosodi-n-propylamine v...spectrometry (IC-MS/MS). Nitrosamines were analyzed using EPA Method 521. N-nitrosodimethylamine ( NDMA ) was 2.6 parts per trillion (ppt) with a...TS/TDS]), and metals (Ca, Cu, Fe, Mg, Mn, K, Na , and Zn). Specific methods are listed in Table 5. ** N-nitrosodimethylamine ( NDMA ), N

Porous, S-bearing silica in metal-sulfide nodules and in the interchondrule clastic matrix in two EH3 chondrites

NASA Astrophysics Data System (ADS)

Lehner, S. W.; Németh, P.; Petaev, M. I.; Buseck, P. R.

2017-11-01

Two new occurrences of porous, S-bearing, amorphous silica are described within metal-sulfide nodules (MSN) and as interchondrule patches in EH3 chondrites SAH 97072 and ALH 84170. This porous amorphous material, which was first reported from sulfide-bearing chondrules, consists of sinewy SiO2-rich areas containing S with minor Na or Ca as well as Fe, Mg, and Al. Some pores contain minerals including pyrite, pyrrhotite, and anhydrite. Most pores appear vacant or contain unidentified material that is unstable under analytical conditions. Niningerite, olivine, enstatite, albite, and kumdykolite occur enclosed within porous silica patches. Porous silica is commonly interfingered with cristobalite suggesting its amorphous structure resulted from high-temperature quenching. We interpret the S-bearing porous silica to be a product of silicate sulfidation, and the Na, Ca, Fe, Mg, and Al detectable within this material are chemical residues of sulfidized silicates and metal. The occurrence of porous silica in the cores of MSN, which are considered to be pre-accretionary objects, suggests the sulfidizing conditions occurred prior to final parent-body solidification. Ubiquitous S-bearing porous silica among sulfide-bearing chondrules, MSN, and in the interchondrule clastic matrix, suggests that similar sulfidizing conditions affected all the constituents of these EH3 chondrites.

Biogeochemical characteristics of Rosa canina grown in hydrothermally contaminated soils of the Gümüşhane Province, Northeast Turkey.

PubMed

Vural, Alaaddin

2015-08-01

Kırkpavli alteration area (Gümüşhane, Northeast Turkey) is contaminated by heavy metals such as Cd, Pb, As, Cu and Zn. The quantity of accumulation of heavy metal trace elements and macroelements in 32 leaves of Rosa canina of the Kırkpavli alteration area has been studied within the scope of geochemical studies. Element contents of samples were assessed using various parameters including descriptive statistics, factor analysis, correlation coefficients and bioaccumulation factor. Concentrations were detected in the acceptable range for Mo, Cu, Pb, Ni, As, Cd, Sb, P, Ti, Na, Se and Sn. Concentrations of Co, Mn, Ba and Hg were detected close to the acceptable values, whereas Zn, Fe, Sr, V, Ca, Cr, Mg, B, Al, K, W, Sc, Cs and Rb concentrations were detected above the acceptable values. Principal component analysis was used to identify the elements that have a close relationship with each other and/or similar origins. It has been concluded that Zn, Cu, As and Mo content of the plant were related to hydrothermal alteration process and they behaved together, whereas Mn and Fe were especially products of weathering conditions, also behaved together. In terms of macroelements, Ca, Mg and Na had similar behaviour, while P and K had the same correlation.

Macrominerals and Trace Element Requirements for Beef Cattle.

PubMed

Costa e Silva, Luiz Fernando; Valadares Filho, Sebastião de Campos; Engle, Terry Eugene; Rotta, Polyana Pizzi; Marcondes, Marcos Inácio; Silva, Flávia Adriane Sales; Martins, Edilane Costa; Tokunaga, Arnaldo Taishi

2015-01-01

Eighty-seven Nellore animals were utilized in this study to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral. The net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals.

Macrominerals and Trace Element Requirements for Beef Cattle

PubMed Central

Costa e Silva, Luiz Fernando; de Campos Valadares Filho, Sebastião; Engle, Terry Eugene; Rotta, Polyana Pizzi; Marcondes, Marcos Inácio; Silva, Flávia Adriane Sales; Martins, Edilane Costa; Tokunaga, Arnaldo Taishi

2015-01-01

Eighty-seven Nellore animals were utilized in this study to estimate net requirements for the maintenance and growth of beef cattle as well as the retention coefficients of 13 minerals: macrominerals (Ca, P, Mg, K, Na, and S) and trace elements (Cu, Fe, Mn, Se, Zn, Co, and Cr). The net requirements for maintenance and the true retention coefficient were estimated by using the regression between apparent retention and intake for each mineral. The net requirement for maintenance (μg/kg BW) and retention coefficients (%) were 163 and 85 for Cu, 2,097 and 53 for Fe, 32.3 and 24 for Mn, 3.72 and 48 for Se, 669 and 0.80 for Zn, 18.4 and 86 for Co, and 22.9 and 78 for Cr. The dietary requirements of macrominerals (g/kg DMI) were 5.12 for Ca, 2.38 for P, 0.96 for Mg, 2.40 for K, 0.79 for Na, and 1.47 for S. This is the first study using Nellore cattle to estimate mineral requirements; considering that Nellore cattle are the most common breed in Brazil and that Brazil is a major beef producer globally, this knowledge can help producers to improve animal performance by supplying the correct amount of minerals. PMID:26657049

Straczekite, a new calcium barium potassium vanadate mineral from Wilson Springs, Arkansas.

USGS Publications Warehouse

Evans, H.T.; Nord, G.; Marinenko, J.; Milton, C.

1984-01-01

Straczekite occurs as a rare secondary mineral in fibrous seams, along with other V minerals (A.M. 64-713), in ore from the vanadium mine in Wilson Springs (formerly Potash Sulfur Springs), Garland County, Arkansas. It forms soft, thin laths of dark greenish black crystals up to 0.5 mm in length. Indexed XRD data are tabulated; strongest lines 3.486(100), 10.449(50), 1.8306(50), 1.9437(15) A; a 11.679, b 3.6608, c 10.636 A, beta 100.53o; space group C2/m, C2 or Cm. Chemical analysis gave V2O5 66.4, V2O4 15.3, Fe2O3 0.9, Na2O 0.4, K2O 1.8, CaO 2.5, BaO 5.5, H2O 7.2, = 100.0, leading to the formula (Ca0.39Ba0.31K0.33Na0.11)- 196(V4+1.59V5+6.31Fe3+0.10)O20.02(H2O)2.9; Dcalc. 3.21 g/cm3. A possible layer structure is discussed. The name is for J. A. Straczek, Chief Geologist at Union Carbide Corp.-R.A.H.

Dynamics of multiple elements in fast decomposing vegetable residues.

PubMed

Cao, Chun; Liu, Si-Qi; Ma, Zhen-Bang; Lin, Yun; Su, Qiong; Chen, Huan; Wang, Jun-Jian

2018-03-01

Litter decomposition regulates the cycling of nutrients and toxicants but is poorly studied in farmlands. To understand the unavoidable in-situ decomposition process, we quantified the dynamics of C, H, N, As, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, and Zn during a 180-d decomposition study in leafy lettuce (Lactuca sativa var. longifoliaf) and rape (Brassica chinensis) residues in a wastewater-irrigated farmland in northwestern China. Different from most studied natural ecosystems, the managed vegetable farmland had a much faster litter decomposition rate (half-life of 18-60d), and interestingly, faster decomposition of roots relative to leaves for both the vegetables. Faster root decomposition can be explained by the initial biochemical composition (more O-alkyl C and less alkyl and aromatic C) but not the C/N stoichiometry. Multi-element dynamics varied greatly, with C, H, N, K, and Na being highly released (remaining proportion<20%), Ca, Cd, Cr, Mg, Ni, and Zn released, and As, Cu, Fe, Hg, Mn, and Pb possibly accumulated. Although vegetable residues serve as temporary sinks of some metal(loid)s, their fast decomposition, particularly for the O-alkyl-C-rich leafy-lettuce roots, suggest that toxic metal(loid)s can be released from residues, which therefore become secondary pollution sources. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of cations on Helicobacter pylori urease activity, release, and stability.

PubMed Central

Pérez-Pérez, G I; Gower, C B; Blaser, M J

1994-01-01

The urease of Helicobacter pylori is an important antigen and appears critical for colonization and virulence. Several studies have indicated a superficial localization for the H. pylori urease, and the purpose of this study was to determine the effects of cations on the release and stability of urease activity from H. pylori cells. Incubation of partially purified H. pylori urease in water containing 1, 5, or 10 mM Ca2+, Mg2+, K+, Na+, EDTA, or EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] had little effect on activity. In contrast, 1 mM Fe3+, Cu2+, Co2+, or Zn2+ substantially (> 80%) inhibited activity, and 10 mM Fe2+, Mn2+, and Ni2+ inhibited about 30% of the activity. Addition of Ca2+ or Mg2+ markedly decreased extraction of urease from intact H. pylori cells by water, but 1 mM Na+, K+, EGTA, or EDTA each had minimal effects on release, suggesting that divalent cations have a role in attachment of urease to H. pylori cells. The stability of enzymatic activity at 4 degrees C was enhanced by addition of glycerol or 2-mercaptoethanol; however, even after loss of activity, full antigenicity for human serum was retained. PMID:8262643

Solubility of Anhydrite (CaSO4) in NaCl-H2O Fluids at High T and P

NASA Astrophysics Data System (ADS)

Newton, R. C.; Manning, C. E.

2003-12-01

Weight losses of single crystals of a very pure natural anhydrite exposed to NaCl solutions of 0-0.3 mol fraction were measured at 600-800 \\deg C and 6-14 kbar. Experimental charges were contained in welded Pt capsules in 1.91 cm-diameter piston-cylinder apparatus with NaCl pressure medium for 5-72 hr. Measurements in initially pure H2O were made with HM, NNO, and MnO2 buffers, as well as without buffering. At 800 \\deg C and 10 kbar, CaSO4 molalities are: MnO2, 0.014 mol/kg H2O; HM, 0.017; NNO, 0.148; and unbuffered, 0.026. Variation in oxygen fugacity thus has a large effect on CaSO4 solubility, increasing with H2S/SO2 in the fluid. Unbuffered (self-buffered) charges gave solubilities much closer to HM than NNO. Melting occurred in the NNO experiment at this P and T. NaCl increases CaSO4 solubility enormously, with m(CaSO4) reaching 5.4, or 23.5 wt. %, at 800 \\deg C, 10 kbar and X(NaCl)=0.3. There is also a very large increase with temperature. Regression of all the data give: log(m-mo) = -1.533 + 0.00291T + (1.441 + 0.00016T)logX(NaCl) + 0.0413(P-10) where mo is molality in pure H2O, P is in kbar, and T is in Kelvins. The very large carrying capacity for sulfate in even mildly saline fluids at high P and T, together with the high oxygen potential generated when these solutions react with FeO in rocks to yield pyrrhotite, indicates that such fluids should be considered as principal agents in S-rich, highly oxidizing processes such as Pinatubo-type volcanic eruptions, certain deep-crustal granulite facies metamorphism, as in Bamble, Norway and Shevaroy Hills, S. India, and the anhydrite-related, oxidized Au ore deposits like Abitibi, Ontario, and Kalgoorlie, Australia.

Chemical Abundances of Seven Outer Halo M31 Globular Clusters from the Pan-Andromeda Archaeological Survey

NASA Astrophysics Data System (ADS)

Sakari, Charli M.

2017-03-01

Observations of stellar streams in M31's outer halo suggest that M31 is actively accreting several dwarf galaxies and their globular clusters (GCs). Detailed abundances can chemically link clusters to their birth environments, establishing whether or not a GC has been accreted from a satellite dwarf galaxy. This talk presents the detailed chemical abundances of seven M31 outer halo GCs (with projected distances from M31 greater than 30 kpc), as derived from high-resolution integrated-light spectra taken with the Hobby Eberly Telescope. Five of these clusters were recently discovered in the Pan-Andromeda Archaeological Survey (PAndAS)-this talk presents the first determinations of integrated Fe, Na, Mg, Ca, Ti, Ni, Ba, and Eu abundances for these clusters. Four of the target clusters (PA06, PA53, PA54, and PA56) are metal-poor ([Fe/H] < -1.5), α-enhanced (though they are possibly less alpha-enhanced than Milky Way stars at the 1 sigma level), and show signs of star-to-star Na and Mg variations. The other three GCs (H10, H23, and PA17) are more metal-rich, with metallicities ranging from [Fe/H] = -1.4 to -0.9. While H23 is chemically similar to Milky Way field stars, Milky Way GCs, and other M31 clusters, H10 and PA17 have moderately-low [Ca/Fe], compared to Milky Way field stars and clusters. Additionally, PA17's high [Mg/Ca] and [Ba/Eu] ratios are distinct from Milky Way stars, and are in better agreement with the stars and clusters in the Large Magellanic Cloud (LMC). None of the clusters studied here can be conclusively linked to any of the identified streams from PAndAS; however, based on their locations, kinematics, metallicities, and detailed abundances, the most metal-rich PAndAS clusters H23 and PA17 may be associated with the progenitor of the Giant Stellar Stream, H10 may be associated with the SW Cloud, and PA53 and PA56 may be associated with the Eastern Cloud.

Spatial and temporal characterization of trace elements and nutrients in the Rawal Lake Reservoir, Pakistan using multivariate analysis techniques.

PubMed

Malik, Riffat Naseem; Nadeem, Muhammad

2011-12-01

Rawal Lake Reservoir is renowned for its ecological significance and is the sole source of drinking water of the third largest city of Pakistan. However, fish kill in recent years and anthropogenic impacts from human-related activities in its catchment area have resulted in deterioration of its surface water quality. This study aims to characterize spatial and temporal variations in surface water quality, identify contaminant sources, and compare their levels with quality guidelines. Surface water samples were collected from 10 sites and analyzed for 27 physicochemical parameters for a period of 2 years on a seasonal basis. Concentration of metals in surface water in pre-monsoon were in the order: Fe > Mg > Ca > Mn > Zn > Ni > Cr > Cu > Co > Pb, whereas in post-monsoon, the order of elemental concentrations was: Ca > Mg > Na > Fe > K > Zn > Cr > Li > Pb > Co > Ni > Cu > Mn > Cd. Metals (Ni, Fe, Zn, and Ca), pH, electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), and nutrients (PO (4) (3-) , NO(3)-N, and SO (4) (2-) ) were measured higher in pre-monsoon, whereas concentration of Cu, Mn, Cr, Co, Pb, Cd, K, Na, Mg, Li, Cl(-), and NH(4)-N were recorded higher in post-monsoon. Results highlighted serious metal pollution of surface water. Mean concentration of Zn, Cd, Ni, Cu, Fe, Cr, and Pb in both seasons and Mn in post-monsoon were well above the permissible level of surface water quality criteria. Results stress the dire need to reduce heavy-metal input into the lake basin and suggest that heavy-metal contamination should be considered as an integral part of future planning and management strategies for restoration of water quality of the lake reservoir.

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.

Ehimeite, NaCa2Mg4CrSi6Al2O22(OH)2: The first Cr-dominant amphibole from the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan

NASA Astrophysics Data System (ADS)

Nishio-Hamane, Daisuke; Ohnishi, Masayuki; Minakawa, Tetsuo; Yamaura, Jun-Ichi; Saito, Shohei; Kadota, Ryo

The first Cr-dominant amphibole, ehimeite, ideally NaCa2Mg4CrSi6Al2O22(OH)2, has been found in a chromitite deposit in the Akaishi Mine, Higashi-Akaishi Mountain, Ehime Prefecture, Japan. Ehimeite occurs as prismatic crystals of up to 1.5 cm in length and 0.5 cm in width and is found in association with chromite, kämmererite (Cr-rich clinochlore), Cr-poor clinochlore, phlogopite, and uvarovite. It is transparent, emerald green to pale green in color with pale green streaks, and has a vitreous luster. Optically, it is biaxial positive with α = 1.644(2), β = 1.647(2), γ = 1.659(2), and 2Vcalc. = 53°. It has a Mohs’ hardness of 6 and densities of 3.08(3) g/cm3 (measured using heavy liquids) and 3.121 g/cm3 (calculated from powder diffraction data and the empirical formula). The empirical formula is (Na0.88K0.07)Σ0.95(Ca1.89Na0.02Mg0.09)Σ2.00(Mg4.03Cr0.62Al0.19Fe3+0.07Fe2+0.07Ti0.03)Σ5.00(Si6.14Al1.86)Σ8.00O22(OH)2 on the basis of O = 22 and OH = 2, and ehimeite mainly forms a solid solution, NaCa2Mg4(Cr, Al)Si6Al2O22(OH)2, with pargasite. It has a monoclinic unit cell with a = 9.9176(14) Å, b = 18.0009(12) Å, c = 5.2850(7) Å, β = 105.400(7)°, V = 909.6 (17) Å3, and Z = 2, and it belongs to the space group C2/m, as refined from powder XRD data. The eight strongest lines in the powder XRD pattern [d (Å), I/I0, hkl] are (3.370, 58, 150), (2.932, 43, 221), (2.697, 81, 151), (2.585, 50, 061), (2.546, 100, 202), (2.346, 42, 351), (2.156, 35, 261), and (1.514, 55, 263). The crystal structure has been refined to R1 = 0.0488 using single-crystal XRD data. It has been concluded that ehimeite in the Akaishi Mine was formed by the reaction of chromitite and the metamorphic fluid in the retrograde stage of serpentinization during the Sanbagawa metamorphism.

VizieR Online Data Catalog: X-Shooter spectroscopy of YSOs in Lupus (Frasca+, 2017)

NASA Astrophysics Data System (ADS)

Frasca, A.; Biazzo, K.; Alcala, J. M.; Manara, C. F.; Stelzer, B.; Covino, E.; Antoniucci, S.

2017-03-01

Membership, atmospheric parameters (Teff, logg, and [Fe/H]), radial velocity (RV), projected rotational velocity (vsini) and veiling at five wavelengths are listed for 102 Lupus YSO candidates in Table 1. Mass and age are also reported in Table 1 for the members, with the exception of subluminous sources. Table 2 reports the full width at 10% maximum of the Hα line and the fluxes in the Hα, Hβ, CaII-IRT, CaII-K, and NaI,D1,2 lines. Table 3 reports the fluxes for Paγ, Paβ, and Brγ measured in the NIR X-Shooter spectra. (3 data files).

Detailed investigation of Na2.24FePO4CO3 as a cathode material for Na-ion batteries

PubMed Central

Huang, Weifeng; Zhou, Jing; Li, Biao; Ma, Jin; Tao, Shi; Xia, Dingguo; Chu, Wangsheng; Wu, Ziyu

2014-01-01

Na-ion batteries are gaining an increased recognition as the next generation low cost energy storage devices. Here, we present a characterization of Na3FePO4CO3 nanoplates as a novel cathode material for sodium ion batteries. First-principles calculations reveal that there are two paths for Na ion migration along b and c axis. In-situ and ex-situ Fe K-edge X-ray absorption near edge structure (XANES) point out that in Na3FePO4CO3 both Fe2+/Fe3+ and Fe3+/Fe4+ redox couples are electrochemically active, suggesting also the existence of a two-electron intercalation reaction. Ex-situ X-ray powder diffraction data demonstrates that the crystalline structure of Na3FePO4CO3 remains stable during the charging/discharging process within the range 2.0–4.55 V. PMID:24595232

Determination of some enzymes and macro- and microelements in stallion seminal plasma and their correlations to semen quality.

PubMed

Pesch, Sandra; Bergmann, Martin; Bostedt, Hartwig

2006-07-15

Seminal plasma is very important for sperm metabolism as well as sperm function and survival and transport in the female genital tract. Analysis of enzyme activities and concentrations of elements can estimate integrity and function of sperm cell membranes. In man much data are available about biochemical analyses of seminal plasma. However, not many studies have been conducted in horses yet. We collected ejaculates from 72 stallions, measured the volume, obtained seminal plasma by centrifugation and examined spermatozoa with light microscopy for motility, concentration, for dead sperm and morphology. Of seminal plasma fluid, we measured activities of aspartate-amino-transferase (AST), gamma-glutamyl-transferase (GGT), alkaline phosphatase (AlP), acid phosphatase (AcP) and lactate-dehydrogenase (LDH) as well as concentrations of sodium (Na(+)), potassium (K(+)), total and ionised calcium (Ca(TOTAL)/Ca(2+)), magnesium (Mg(2+)), phosphate (P), chloride (Cl), copper (Cu), iron (Fe) and zinc (Zn). In addition, correlations among different parameters in light microscopy and seminal plasma were statistically examined by using the Spearman rank correlation coefficient. Median enzyme activities for AST, GGT, AlP, AcP and LDH were 80.0, 7,500, 30,200, 20.0, 81.0 IU/L, respectively. Concentrations of Na(+), K(+), Ca(TOTAL), Ca(2+), Mg(2+), P, Cl were 110.5, 22.1, 2.9, 1.7, 3.1, 1.1 and 114.5 mmol/L, and of microelements Cu, Fe and Zn were 17.8, 1.9 and 13.2 micromol/L, respectively. Furthermore, we found significant correlations between semen volume as well as sperm concentration and AST, GGT, AlP, AcP and LDH as well as Fe and Zn. This made us propose a primary testicular and epididymal origin of these parameters. Significant correlation between GGT and motility may be a sign for its function for cell protection against free radicals. LDH activity significantly correlates with motility and progressive motility, live:dead-ratio and pathomorphology. In our study, LDH seems to be the most predictive enzyme for semen quality. This is the first report about GGT, AcP and LDH activities as well as iron in equine seminal plasma.

Effects of a low severity prescribed fire on water-soluble elements in ash from a cork oak (Quercus suber) forest located in the northeast of the Iberian Peninsula

USGS Publications Warehouse

Pereira, P.; beda, X.; Martin, D.; Mataix-Solera, J.; Guerrero, C.

2011-01-01

Wildfire is the major disturbance in Mediterranean forests. Prescribed fire can be an alternative to reduce the amount of fuel and hence decrease the wildfire risk. However the effects of prescribed fire must be studied, especially on ash properties, because ash is an important nutrient source for ecosystem recovery. The aim of this study is to determine the effects of a low severity prescribed fire on water-soluble elements in ash including pH, electrical conductivity (EC), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), silica (SiO2) and total sulphur (TS). A prescribed fire was conducted in a cork oak (Quercus suber) (Q.S) forest located in the northeast part of the Iberian Peninsula. Samples were collected from a flat plot of 40??70m mainly composed of Q.S and Quercus robur (Q.R) trees. In order to understand the effects of the prescribed fire on the soluble elements in ash, we conducted our data analysis on three data groups: all samples, only Q.S samples and only Q.R samples. All three sample groups exhibited a significant increase in pH, EC (p<0.001), water-soluble Ca, Mg, Na, SiO2 and TS and a decrease in water-soluble Mn, Fe and Zn. Differences were identified between oak species for water-soluble K, Al and Fe. In Q.S samples we registered a significant increase in the first two elements p<0.001 and p<0.01, respectively, and a non-significant impact in the third, at p<0.05. In Q.R data we identified a non-significant impact on water-soluble K and Al and a significant decrease in water-soluble Fe (p<0.05). These differences are probably due to vegetation characteristics and burn severity. The fire induced a higher variability in the ash soluble elements, especially in Q.S samples, that at some points burned with higher severity. The increase of pH, EC, Ca, Mg, Na and K will improve soil fertility, mainly in the study area where soils are acidic. The application of this low severity prescribed fire will improve soil nutrient status without causing soil degradation and thus is considered to be a good management strategy. ?? 2010 Elsevier Inc.

Effects of a low severity prescribed fire on water-soluble elements in ash from a cork oak (Quercus suber) forest located in the northeast of the Iberian Peninsula.

PubMed

Pereira, Paulo; Ubeda, Xavier; Martin, Deborah; Mataix-Solera, Jorge; Guerrero, César

2011-02-01

Wildfire is the major disturbance in Mediterranean forests. Prescribed fire can be an alternative to reduce the amount of fuel and hence decrease the wildfire risk. However the effects of prescribed fire must be studied, especially on ash properties, because ash is an important nutrient source for ecosystem recovery. The aim of this study is to determine the effects of a low severity prescribed fire on water-soluble elements in ash including pH, electrical conductivity (EC), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), aluminum (Al), manganese (Mn), iron (Fe), zinc (Zn), silica (SiO(2)) and total sulphur (TS). A prescribed fire was conducted in a cork oak (Quercus suber) (Q.S) forest located in the northeast part of the Iberian Peninsula. Samples were collected from a flat plot of 40×70m mainly composed of Q.S and Quercus robur (Q.R) trees. In order to understand the effects of the prescribed fire on the soluble elements in ash, we conducted our data analysis on three data groups: all samples, only Q.S samples and only Q.R samples. All three sample groups exhibited a significant increase in pH, EC (p<0.001), water-soluble Ca, Mg, Na, SiO(2) and TS and a decrease in water-soluble Mn, Fe and Zn. Differences were identified between oak species for water-soluble K, Al and Fe. In Q.S samples we registered a significant increase in the first two elements p<0.001 and p<0.01, respectively, and a non-significant impact in the third, at p<0.05. In Q.R data we identified a non-significant impact on water-soluble K and Al and a significant decrease in water-soluble Fe (p<0.05). These differences are probably due to vegetation characteristics and burn severity. The fire induced a higher variability in the ash soluble elements, especially in Q.S samples, that at some points burned with higher severity. The increase of pH, EC, Ca, Mg, Na and K will improve soil fertility, mainly in the study area where soils are acidic. The application of this low severity prescribed fire will improve soil nutrient status without causing soil degradation and thus is considered to be a good management strategy. Copyright © 2010 Elsevier Inc. All rights reserved.

Transmembrane Na+ and Ca2+ electrochemical gradients in cardiac muscle and their relationship to force development

PubMed Central

1982-01-01

Na+- and CA2+-sensitive microelectrodes were used to measure intracellular Na+ and Ca2+ activities (alpha iCa) of sheep ventricular muscle and Purkinje strands to study the interrelationship between Na+ and Ca2+ electrochemical gradients (delta muNa and delta muCa) under various conditions. In ventricular muscle, alpha iNa was 6.4 +/- 1.2 mM and alpha iCa was 87 +/- 20 nM ([Ca/+] = 272 nM). A graded decrease of external Na+ activity (alpha oNa) resulted in decrease of alpha iNa, and increase of alpha iCa. There was increase of twitch tension in low- alpha oNa solutions, and occasional increase of resting tension in 40% alpha oNa. Increase of external Ca2+ (alpha oCa) resulted in increase of alpha iCa and decrease of alpha iNa. Decrease of alpha oCa resulted in decrease of alpha iCa and increase of alpha iNa. The apparent resting Na-Ca energy ratio (delta muCa/delta muNa) was between 2.43 and 2.63. When the membrane potential (Vm) was depolarized by 50 mM K+ in ventricular muscle, Vm depolarized by 50 mV, alpha iNa decreased, and alpha iCa increased, with the development of a contracture. The apparent energy coupling ratio did not change with depolarization. 5 x 10(-6) M ouabain induced a large increase in alpha iNa ad alpha iCa, accompanied by an increase in twitch and resting tension. Under the conditions we have studied, delta muNa and delta muCa appeared to be coupled and n was nearly constant at 2.5, as would be expected if the Na-Ca exchange system was able to set the steady level of alpha iCa. Tension threshold was about 230 nM alpha iCa. The magnitude of twitch tension was directly related to alpha iCa. PMID:6292328

Geochemistry and genesis of the angrites

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

Mittlefehldt, D.W.; Lindstrom, M.M.

1990-11-01

The angrites Angra dos Reis, LEW86010, and LEW87051 are petrologically and compositionally similar achondrites. All angrites have high FeO/MnO ratios of 80-94 and very low CI normalized Na/Sm ratios of 0.001-0.003. High abundances of oxidized Fe and low abundances of moderately volatile Na most likely resulted from parent body processes, such as magmatic outgassing, rather than nebular processes. All angrites have fractionated Ca/Al ratios, with Angra dos Reis exhibiting the most extreme ratio (3.1 {times} CI). For Angra dos Reis, cumulus material may be the cause of the high Ca/Al ratio. Refractory element abundances of LEW86010 and LEW87051 show similarmore » patterns, while Angra dos Reis has both greater enrichments in these elements and more fractionated patterns. Compositional and petrologic constraints indicate that LEW86010 and LEW87051 are related via olivine control. The refractory element abundances and mg{number sign} of LEW86010 can be approximated by removal of olivine from LEW87051, suggesting that LEW86010 may be a residual melt from a LEW87051-like precursor. Alternatively, LEW87051 may have formed via olivine accumulation from a LEW86010-like precursor. The differences between the LEW86010-LEW87051 duo and Angra dos Reis suggest that either the angrite parent body was heterogeneous or that Angra dos Reis was formed on a separate parent body. Based on FeO/MnO ratios and normative mineralogies, the angrite parent body(ies) may be similar in bulk composition to one of the carbonaceous chondrite groups, particularly CI-CM-CO.« less

Possible Links Among Iron Reduction, Silicate Weathering, and Arsenic Mobility in the Mississippi River Alluvial Aquifer in Louisiana

NASA Astrophysics Data System (ADS)

Borrok, D. M.; Lenz, R. M.; Jennings, J. E.; Gentry, M. L.; Vinson, D. S.

2017-12-01

The Lower Mississippi River Alluvial Aquifer (LMRAA) is a critical groundwater resource for Arkansas, Mississippi, and Louisiana. Part of the aquifer in Louisiana contains waters rich in Na, HCO3, Fe, and As. We hypothesize that CO2 generated from dissimilatory iron reduction (DIR) within the aquifer acts to weather Na-bearing silicates, contributing Na and HCO3, which may influence the mobility of As. We examined the geochemistry of the aquifer using historical and new data collected from the Louisiana Department of Environmental Quality (LDEQ). Major and trace element data were collected from about 25 wells in the LMRAA in Louisiana every three years from 2001-2016. Samples collected in 2016 were additionally analyzed for water isotopes and the δ13C of dissolved inorganic carbon (DIC). Results suggest that groundwater in the LMRAA can be broken into two broad categories, (1) water with a molar Na/Cl ratio near 1 and/or high salinity, and (2) water with excess Na (i.e., the molar concentration of Na is greater than that of Cl) that is often higher in alkalinity (up to 616 mg/L as CaCO3), Fe (up to 21 mg/L), and sometimes As (up to 67 µg/L). Concentrations of dissolved Fe were found to correlate, at least weakly, with alkalinity and Na excess. Six of the approximately 25 wells historically sampled consistently had concentrations of As >10 µg/L. These locations generally correspond with groundwater characterized by higher Fe, alkalinity, and Na-excess. Initial results for δD and δ18O suggest that more isotopically depleted waters are sourced from the Mississippi River, whereas local precipitation recharges the aquifer farther from the river (δ18O ranged from -7.5‰ to -3.5‰). Part of the δ13C-DIC variation (-17.4‰ to -10.6‰) is consistent with pH modification (6.5-7.7) along differing horizontal and vertical flow paths in the aquifer. This geochemistry appears to be controlled in part by geology. Areas nearer to the current Mississippi River where alluvial valley train deposits are absent have thicker layers of Holocene-age clays, which may provide more labile organic matter for DIR, leading to higher concentrations of dissolved Fe in groundwater. Overall, these data are consistent with the hypothesized linkages among DIR, silicate weathering, and high (> 10µg/L) concentrations of As in parts of the LMRAA.

Documentation of the appearance of a caviar-type deposit in Oven 1 following a large scale experiment for heating oil with Upper Silesian coal (in German)

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

Rank

1942-03-26

When the oven was disassembled after the test, small kernels of porous material were found in both the upper and lower portion of the oven to a depth of about 2 m. The kernels were of various sizes up to 4 mm. From 1,300 metric ..cap alpha..ons of dry coal, there were 330 kg or the residue of 0.025% of the coal input. These kernels brought to mind deposits of spheroidal material termed ''caviar'', since they had rounded tops. However, they were irregularly long. After multiaxis micrography, no growth rings were found as in Leuna's lignite caviar. So, it wasmore » a question of small particles consisting almost totally of ash. The majority of the composition was Al, Fe, Na, silicic acid, S and Cl. The sulfur was found to be in sulfide form and Cl in a volatile form. The remains did not turn to caviar form since the CaO content was slight. The Al, Fe, Na, silicic acid, S and Cl were concentrated in comparison to coal ash and originate apparently from the catalysts (FeSO/sub 4/, Bayermasse, and Na/sub 2/S). It was notable that the Cl content was so high. 2 graphs, 1 table« less

Does laboratory automation for the preanalytical phase improve data quality?

PubMed

Lima-Oliveira, Gabriel; Lippi, Giuseppe; Salvagno, Gian Luca; Danese, Elisa; Montagnana, Martina; Brocco, Giorgio; Voi, Monica; Picheth, Geraldo; Guidi, Gian Cesare

2013-10-01

Our aim was to evaluate whether automation for the preanalytical phase improves data quality. Blood from 100 volunteers was collected into two vacuum tubes. One sample from each volunteer was respectively assigned to (G1) traditional processing, starting with centrifugation at 1200 g for 10 min, and (G2) the MODULAR PRE-ANALYTICALS EVO-MPA system. The routine clinical chemistry tests were performed in duplicate on the same instrument Cobas 6000 module. G1 samples were uncapped manually and immediately placed into the instrument. G2 samples were directly fed from the MPA system to the instrument without further staff intervention. At the end, (1) the G1 samples were stored for 6 h at 4 °C as prescribed in our accredited laboratory and (2) the G2 samples were stored for 6 h in the MPA output buffer. Results from G1 and G2, before and after storage, were compared. Significant increases were observed in G1 compared with G2 samples as follows: (1) before storage for alkaline phosphatase (ALP), lactate dehydrogenase (LDH), phosphate (P), magnesium (MG), iron (FE), and hemolysis index and (2) after storage for total cholesterol (COL), triglycerides (TG), total protein (TP), albumin (ALB), blood urea nitrogen (BUN), creatinine (CRE), uric acid (UA), ALP, pancreatic amylase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), g-glutamyltransferase (GGT), LDH, creatine kinase (CK), calcium (CA), FE, sodium (NA), potassium (K), and hemolysis index. Moreover, significant increases were observed in (3) G1-after versus G1-before storage samples for COL, high-density lipoprotein cholesterol, TG, TP, ALB, BUN, CRE, UA, AST, ALT, GGT, LDH, P, CA, MG, FE, NA, K, and hemolysis index and (4) G2-after versus G2-before storage only for BUN, AST, LDH, P, and CA. In conclusion, our results show that the MPA system improves the quality of laboratory testing.

Coupled extremely light Ca and Fe isotopes in peridotites

NASA Astrophysics Data System (ADS)

Zhao, Xinmiao; Zhang, Zhaofeng; Huang, Shichun; Liu, Yufei; Li, Xin; Zhang, Hongfu

2017-07-01

Large metal stable isotopic variations have been observed in both extraterrestrial and terrestrial samples. For example, Ca exhibits large mass-dependent isotopic variation in terrestrial igneous rocks and mantle minerals (on the order of ∼2‰ variation in 44Ca/40Ca). A thorough assessment and understanding of such isotopic variations in peridotites provides important constraints on the evolution and compositon of the Earth's mantle. In order to better understand the Ca and Fe isotopic variations in terrestrial silicate rocks, we report Ca isotopic compositions in a set of peridotitic xenoliths from North China Craton (NCC), which have been studied for Fe isotopes. These NCC peridotites have large Ca and Fe isotopic variations, with δ44/40Ca ranging from -0.08 to 0.92 (delta value relative to SRM915a) and δ57/54Fe (delta value relative to IRMM-014) ranging from -0.61 to 0.16, and these isotopic variations are correlated with large Mg# (100 × Mg/(Mg + Fe) molar ratio) variation, ranging from 80 to 90. Importantly, NCC Fe-rich peridotites have the lowest 44Ca/40Ca and 57Fe/54Fe ratios in all terrestrial silicate rocks. In contrast, although ureilites, mantle rocks from a now broken differentiated asteroid(s), have large Mg# variation, from 70 to 92, they have very limited δ57Fe/54Fe variation (0.03-0.21, delta value relative to IRMM-014). Our model calculations show that the coupled extremely light Ca-Fe isotopic signatures in NCC Fe-rich peridotites most likely reflect kinetic isotopic fractionation during melt-peridotite reaction on a timescale of several to 104 years. In addition, our new data and compiled literature data show a possible compositional effect on the inter-mineral Ca isotopic fractionation between co-existing clinopyroxene and orthopyroxene pairs.

Equilibrium coexistence of three amphiboles

USGS Publications Warehouse

Robinson, P.; Jaffe, H.W.; Klein, C.; Ross, M.

1969-01-01

Electron probe and wet chemical analyses of amphibole pairs from the sillimanite zone of central Massachusetts and adjacent New Hampshire indicated that for a particular metamorphic grade there should be a restricted composition range in which three amphiboles can coexist stably. An unequivocal example of such an equilibrium three amphibole rock has been found in the sillimanite-orthoclase zone. It contains a colorless primitive clinoamphibole, space group P21/m, optically and chemically like cummingtonite with blue-green hornblende exsolution lamellae on (100) and (-101) of the host; blue-green hornblende, space group C2/m, with primitive cummingtonite exsolution lamellae on (100) and (-101) of the host; and pale pinkish tan anthophyllite, space group Pnma, that is free of visible exsolution lamellae but is a submicroscopic intergrowth of two orthorhombic amphiboles. Mutual contacts and coarse, oriented intergrowths of two and three host amphiboles indicate the three grew as an equilibrium assemblage prior to exsolution. Electron probe analyses at mutual three-amphibole contacts showed little variation in the composition of each amphibole. Analyses believed to represent most closely the primary amphibole compositions gave atomic proportions on the basis of 23 oxygens per formula unit as follows: for primitive cummingtonite (Na0.02Ca0.21- Mn0.06Fe2+2.28Mg4.12Al0.28) (Al0.17Si7.83), for hornblende (Na0.35Ca1.56Mn0.02Fe1.71Mg2.85Al0.92) (Al1.37Si6.63), and for anthophyllite (Na0.10Ca0.06Mn0.06Fe2.25Mg4.11Al0.47) (Al0.47Si7.53). The reflections violating C-symmetry, on X-ray single crystal photographs of the primitive cummingtonite, are weak and diffuse, and suggest a partial inversion from a C-centered to a primitive clinoamphibole. Single crystal photographs of the anthophyllite show split reflections indicating it is an intergrowth of about 80% anthophyllite and about 20% gedrite which differ in their b crystallographic dimensions. Split reflections are characteristic of all analyzed orthorhombic amphiboles so far examined from Massachusetts and New Hampshire except the most aluminous gedrites, and the relative intensity of the gedrite reflections is roughly proportional to the degree of Na and Al substitution. Thin sections of a few of these anthophyllite specimens show lamellae parallel to (010) that are just resolved with a high power objective. ?? 1969 Springer-Verlag.

Topotactic redox chemistry of NaFeAs in water and air and superconducting behavior with stoichiometry change.

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

Todorov, I.; Chung, D. Y.; Claus, H.

2010-07-13

We report experimental evidence that shows superconductivity in NaFeAs occurs when it is Na deficient. The oxidation of NaFeAs progresses differently in water and in air. In water the material oxidizes slowly and slightly retaining the original anti-PbFCl structure. In air NaFeAs oxidizes topotactically quickly and extensively transforming to the ThCr{sub 2}Si{sub 2} structure type. Water acts as a mild oxidizing agent on the FeAs layer by extracting electrons and Na{sup +} cations from the structure, while oxidation in air is more extensive and leads to change in structure type from NaFeAs to NaFe{sub 2}As{sub 2}. The superconducting transition temperaturemore » moves dramatically during the oxidation process. Exposed to water for an extended time period NaFeAs shows a substantial increase in T{sub c} up to 25 K with contraction of unit cell volume. NaFe{sub 2}As{sub 2}, the air oxidized product, shows T{sub c} of 12 K. We report detailed characterization of the redox chemistry and transformation of NaFeAs in water and air using single crystal and powder X-ray diffraction, magnetization studies, transmission electron microscopy, Moessbauer spectroscopy, pOH and elemental analysis.« less

Chemical Composition by the APXS along the Downhill Traverse of the Mars Exploration Rover Spirit at Gusev Crater

NASA Technical Reports Server (NTRS)

Bruckner, J.; Dreibus, G.; Gellert, R.; Clark, B.C.; Cohen, B.; McCoy, T.; Ming, D.W.; Mittlefehldt, D.W.; Yen, A.; Athena Science Team

2006-01-01

The Alpha Particle X-ray Spectrometer (APXS) onboard the Mars Exploration Rover Spirit continues to determine the elemental composition of samples at Gusev Crater. Starting around sol 600 the rover descended Husband Hill, which is part of the Columbia Hills, visited the inner basin with a large dune field, called 'El Dorado', and parked at Low Ridge to conserve energy during the martian winter. Many unique samples were discovered by the instruments onboard Spirit during her downhill traverse. Here, we report only on the chemical data obtained by the APXS. The compositions of some of the soil samples are comparable to the mean soil determined along the earlier traverse. However, a light-toned subsurface sample (disturbed by the rover wheels), called Dead Sea Samra , showed the highest sulfur content of all soil samples, the lowest Na, Mg, Al, Cl, K, Ca, Ti, Mn, and Zn, among the lowest Si and P, and among the highest Cr, Fe and Ni. Assuming ferric sulfate as a major mineral, large amounts of a pure silica phase must be present. Color and quantity of Dead Sea Samra resemble somewhat an earlier soil called Paso Robles , though the latter is a mixture of sulfates with phosphate-rich soil. Manganese in Dead Sea Samra is so low that the Fe/Mn ratio exceeds 300, a value that has never been found previously on Mars (Fe/Mn ratio of 46 for Gusev basalts), indicating that only Fe(3+) occurs. The dune field El Dorado contained granulated material that exhibited the highest Mg and Ni concentrations and the lowest S and Cl compared to all other soils implying an enrichment of olivine-rich sands. Two outcrops, called Algonquin and Comanche , revealed compositions that differ significantly from those of earlier outcrops as they have the highest concentrations of Mg, Fe, and Ni (except for Ni in Independence) and the lowest of Al, K (detection limit), Ca, and Ti of all brushed and almost all abraded rocks. Normative estimates assign them the highest olivine contents ever found for martian rocks and a very mafic nature based on their high Mg/(Mg+Fe) and low Al, Ca and Na. Their significantly high Ni contents point to a different source than the Gusev plains basalts. The elemental compositions of samples encountered during the downhill traverse revealed a larger chemical diversity of the Columbia Hills than the uphill trek already published.

Nutritional composition of school meals serving children from 7 to 36 months of age in municipal day-care centres in the metropolitan area of Curitiba, Paraná, Brazil.

PubMed

Retondario, Anabelle; Silva, Débora Letícia Frizzi; Salgado, Silvana Magalhães; Alves, Márcia Aurelina de Oliveira; Ferreira, Sila Mary Rodrigues

2016-06-01

The Brazilian National School Feeding Program (PNAE) seeks to meet student's nutritional needs during the period they remain in school. This study aimed to determine the nutritional composition of meals provided in municipal day-care centres serving children of 7-11 months (group A) and 12-36 months (group B) of age and to compare observed values with the PNAE's and dietary reference intakes' (DRI) recommendations. This cross-sectional study was conducted in 4 day-care centres in the metropolitan area of Curitiba, Paraná, Brazil, between June and November 2013. Food samples of six daily meals were collected during 20 non-consecutive days, totalling 120 samples. For each meal, average served and consumed portions were submitted for laboratory analysis of moisture, ash, proteins, lipids, carbohydrates, dietary fibre, Na, Ca and Fe and compared with the PNAE's and DRI's values. No statistically significant difference was found between age groups (P=0·793) regarding portion sizes and nutritional composition. The same menu was offered to both groups in 95 % of the meals (n 114), although the groups' nutritional needs were different. For group A, served meals met PNAE's recommendations for energy, carbohydrates, proteins, Na and Ca content, and consumed portions provided 70 % of the nutritional needs for carbohydrates, proteins and Ca. For group B, served portions complied with the PNAE's values for proteins, Na and Ca. Proteins and Na reached 70 % of the nutritional needs when consumed food was evaluated. School feeding in day-care centres partially meet PNAE's guidelines and children's nutritional requirements, contradicting the primary objective established by the national programme.

Effect of NaFeEDTA-fortified soy sauce on zinc absorption in children.

PubMed

Li, Min; Wu, Jinghuan; Ren, Tongxiang; Wang, Rui; Li, Weidong; Piao, Jianhua; Wang, Jun; Yang, Xiaoguang

2015-03-01

NaFeEDTA has been applied in many foods as an iron fortificant and is used to prevent iron deficiency in Fe-depleted populations. In China, soy sauce is fortified with NaFeEDTA to control iron deficiency. However, it is unclear whether Fe-fortified soy sauce affects zinc absorption. To investigate whether NaFeEDTA-fortified soy sauce affects zinc absorption in children, sixty children were enrolled in this study and randomly assigned to three groups (10 male children and 10 female children in each group). All children received daily 3 mg of (67)Zn and 1.2 mg of dysprosium orally, while the children in the three groups were supplemented with NaFeEDTA-fortified soy sauce (6 mg Fe, NaFeEDTA group), FeSO₄-fortified soy sauce (6 mg Fe, FeSO₄ group), and no iron-fortified soy sauce (control group), respectively. Fecal samples were collected during the experimental period and analyzed for the Zn content, (67)Zn isotope ratio and dysprosium content. The Fe intake from NaFeEDTA-fortified and FeSO₄-fortified groups was significantly higher than that in the control group (P < 0.0001). The daily total Zn intake was not significantly different among the three groups. There were no significant differences in fractional Zn absorption (FZA) (P = 0.3895), dysprosium recovery (P = 0.7498) and Zn absorption (P = 0.5940) among the three groups. Therefore, NaFeEDTA-fortified soy sauce does not affect Zn bioavailability in children.

Discovery of composite diopside-magnetite lamellae in discrete olivine crytals from Colorado Plateau diatremes: indication of former hydrous ringwoodite

NASA Astrophysics Data System (ADS)

Sakamaki, K.; Sato, Y.; Marshall, E. W., IV; Ogasawara, Y.

2016-12-01

We investigate composite diopside (Di) + magnetite (Mt) lamellae in olivine crystals from Oligocene diatremes of serpentinized ultramafic microbreccia located at Buell Park (AZ) and Green Knobs (NM) in the Colorado Plateau, and propose their genesis as breakdown products of precursor hydrous ringwoodite (γ-olivine) lamellae coexisting with α-olivine host. Among a hundred olivines (2-5 mm across, Fo89-93 in mol%) from both localities, the Di + Mt composite lamellae are recognized in only 15 of relatively Fe-rich grains (Fo89-91.5). The olivine host contains minor amounts of Ca (< 0.01 wt% CaO), Mn, Ni, and Co. Lamellar Di (Di95) contains minor amounts of Al, Na, Cr, Mn, and Ni. Lamellar Mt contains Cr (5.0-43.0 wt% Cr2O3) with minor amounts of Si, Ti, Al, Mn, Ni, and Co. The area fractions of olivine host and the lamellae in a typical grain (sample no. BP02-3) were measured at 98.8 % of the host and 1.2 % of the lamellae that are composed of Di:Mt = 85:15 to 53:47, average 66:34. The estimated average CaO content in a lamella reaches 17 wt% and the reintegrated CaO in the host and the lamellae is 0.22 wt%.We propose that Fe3+ in lamellar Mt was produced by dehydration of hydrous precursor phase via the reaction, Fe2+ + OH- = Fe3+ + O2- + 1/2H2. Converting Fe3+ into Fe2+ in the precursor phase based on this reaction, the composition satisfies the stoichiometry of olivine (X2TO4). Thus, the pre-existing phase certainly is of hydrous and contains Ca and other components with olivine stoichiometry. The most likely phase is lamellar hydrous ringwoodite. The precursor phase, hydrous ringwoodite, might have occurred as lamellae with α-olivine host and have probably decomposed by the following reaction, (1+X+Y+Z) hydrous ringwoodite → α-olivine + X Di + Y Mt + Z H2 (where X:Y:Z=2:1:1). The composite Di-Mt lamellae after hydrous ringwoodite lamellae in α-olivine host certainly suggest the materials originated from a deep mantle setting at least 300 km.

Signature of Metallic ion in the upper atmosphere of Mars following the passage of comet C/2013 A1 (Siding Spring)

NASA Astrophysics Data System (ADS)

Benna, M.; Grebowsky, J. M.; Mahaffy, P. R.; Plane, J. M. C.; Yelle, R. V.; Jakosky, B. M.

2017-09-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission made the first in situ detection of metal ions in the upper atmosphere of Mars. These ions result from the ablation of dust particles from comet Siding Spring. This detection was carried out by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the MAVEN spacecraft. Metal ions of Na, Mg, Al, K, Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn, and possibly of Si, and Ca, were identified in the ion spectra collected at altitudes of 185 km. The measurements revealed that Na ion was the most abundant species, and that the remaining metals were depleted with respect to the CI (type 1 carbonaceous Chondrites) abundance of Na ion.

Optical measurements of Na-Ca-K exchange currents in intact outer segments isolated from bovine retinal rods

PubMed Central

1991-01-01

The properties of Na-Ca-K exchange current through the plasma membrane of intact rod outer segments (ROS) isolated from bovine retinas were studied with the optical probe neutral red. Small cellular organelles such as bovine ROS do not offer an adequate collecting area to measure Na-Ca-K exchange currents with electrophysiological techniques. This study demonstrates that Na-Ca-K exchange current in bovine ROS can be measured with the dye neutral red and dual-wavelength spectrophotometry. The binding of neutral red is sensitive to transport of cations across the plasma membrane of ROS by the effect of the translocated cations on the surface potential of the intracellular disk membranes (1985. J. Membr. Biol. 88: 249-262). Electrogenic Na+ fluxes through the ROS plasma membrane were measured with a resolution of 10(5) Na+ ions/ROS per s, equivalent to a current of approximately 0.01 pA; maximal electrogenic Na-Ca-K exchange flux in bovine ROS was equivalent to a maximal exchange current of 1-2 pA. Electrogenic Na+ fluxes were identified as Na-Ca-K exchange current based on a comparison between electrogenic Na+ flux and Na(+)-stimulated Ca2+ release with respect to flux rate, Na+ dependence, and ion selectivity. Neutral red monitored the net entry of a single positive charge carried by Na+ for each Ca2+ ion released (i.e., monitored the Na-Ca-K exchange current). Na-Ca-K exchange in the plasma membrane of bovine ROS had the following properties: (a) Inward Na-Ca-K exchange current required internal Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 0.9 microM), whereas outward Na-Ca-K exchange current required both external Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 1.1 microM) and external K+. (b) Inward Na-Ca-K exchange current depended in a sigmoidal manner on the external Na+ concentration, identical to Na(+)-stimulated Ca2+ release measured with Ca(2+)- indicating dyes. (c) The neutral red method was modified to measure Ca(2+)-activated K+ fluxes (half-maximal stimulation at 2.7 microM free Ca2+) via the Na-Ca-K exchanger in support of the notion that the rod Na-Ca exchanger is in effect a Na-Ca-K exchanger. (d) Competitive interactions between Ca2+ and Na+ ions on the exchanger protein are described. PMID:1722239

Formation and composition of the moon. [carbonaceous meteorites

NASA Technical Reports Server (NTRS)

Anderson, D. L.

1974-01-01

Many of the properties of the moon are discussed including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr and the REE and the depletion in Fe, Rb, K, Na and other volatiles which could be understood if the moon represents a high temperature condensate from the solar nebula. Thermodynamic calculations show that Ca, Al and Ti rich compounds condense first in a cooling nebula. The initial high temperature mineralogy is gehlenite, spinel, perovskite, Ca-Al-rich pyroxenes and anorthite. Inclusions in Type III carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and, in addition, are highly enriched in refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior.

Total-diet study: dietary intakes of macro elements and trace elements in Italy.

PubMed

Lombardi-Boccia, Ginevra; Aguzzi, Altero; Cappelloni, Marsilio; Di Lullo, Giuseppe; Lucarini, Massimo

2003-12-01

The present study provides the dietary intakes of macro elements (Ca, Mg, Na, K, P) and trace elements (Fe, Zn, Cu, Se) from the Italian total diet. The contribution of the most representative food groups of the total diet (cereals and cereal products, vegetables, fruit, milk and dairy products, meat and meat products, fish) to the daily intakes of these nutrients was also evaluated. The Italian total diet was formulated following the 'market-basket' approach. Cereals represented the primary sources of Cu (35 %), Fe (30 %) and Mg (27 %). About 89 % of the total daily intake of Fe was derived from plant foods. The vegetables food group was the main source of dietary K (27 %). Most of the Ca (59 %) and P (27 %) was derived from the milk-and-dairy food group. Of the dietary Zn, 41 % was provided by meat, which, together with the fish food group, was the primary source of Se (20 %). The adequacy of the Italian total diet with respect to nutritional elements was assessed by comparing the daily intakes with the average requirement values of the Italian recommended dietary allowances. The present findings indicated that the dietary patterns of the Italian total diet were generally consistent with current Italian dietary recommendations for both macro and trace elements. The major concern was for Ca, for which daily intake was 76 % of the average recommendation for the Italian population. It should not be ruled out that there could be a potential risk of inadequate Fe intake in some segments of the population.

Cool DZ white dwarfs II: compositions and evolution of old remnant planetary systems

NASA Astrophysics Data System (ADS)

Hollands, M. A.; Gänsicke, B. T.; Koester, D.

2018-06-01

In a previous study, we analysed the spectra of 230 cool (Teff < 9000 K) white dwarfs exhibiting strong metal contamination, measuring abundances for Ca, Mg, Fe and in some cases Na, Cr, Ti, or Ni. Here, we interpret these abundances in terms of the accretion of debris from extrasolar planetesimals, and infer parent body compositions ranging from crust-like (rich in Ca and Ti) to core-like (rich in Fe and Ni). In particular, two white dwarfs, SDSS J0823+0546 and SDSS J0741+3146, which show log [Fe/Ca] > 1.9 dex, and Fe to Ni ratios similar to the bulk Earth, have accreted by far the most core-like exoplanetesimals discovered to date. With cooling ages in the range 1-8 Gyr, these white dwarfs are among the oldest stellar remnants in the Milky Way, making it possible to probe the long-term evolution of their ancient planetary systems. From the decrease in maximum abundances as a function of cooling age, we find evidence that the arrival rate of material on to the white dwarfs decreases by three orders of magnitude over a ≃ 6.5 Gyr span in white dwarf cooling ages, indicating that the mass-reservoirs of post-main sequence planetary systems are depleted on a ≃ 1 Gyr e-folding time-scale. Finally, we find that two white dwarfs in our sample are members of wide binaries, and both exhibit atypically high abundances, thus providing strong evidence that distant binary companions can dynamically perturb white dwarf planetary systems.

Spatial and mineralogic variation of Na-Ca alteration in Laramide porphyry systems of Arizona

NASA Astrophysics Data System (ADS)

Runyon, S.; Seedorff, E.; Barton, M. D.; Mazdab, F. K.; Lecumberri-Sanchez, P.; Steele-MacInnis, M.

2017-12-01

Na-Ca alteration is characterized by the metasomatic addition of Ca ± Na and the loss of K. Minor volumes of Na-Ca alteration in Laramide porphyry systems develops from 3 to 8 km paleodepth. Mineral assemblages, mineral compositions, hydrogen isotopes, whole-rock analyses, and reconnaissance fluid inclusion characteristics have been documented for Na-Ca alteration in Laramide porphyry systems such as Tea Cup and Sierrita. Volumetrically minor Na-Ca alteration in Laramide porphyry systems documented in this study commonly takes the form of one of three mineral assemblages: albite-epidote-chlorite, Na-plagioclase-actinolite ± epidote, and garnet- or diopside-stable Na-plagioclase-actinolite ± epidote. These different Na-Ca mineral assemblages have broad spatial relationships, from shallow albite-chlorite-epidote to deeper Na-plagioclase-actinolite within a given district. Hydrogen isotope data on Na-Ca alteration minerals shows consistently distinct δD compositions of Na-Ca alteration minerals compared to igneous minerals in a given district. Further, calculated hydrogen isotope composition of fluids in equilibrium with Na-Ca alteration minerals are consistently enriched in δD compared to magmatic-hydrothermal fluids. Whole-rock analyses show consistent losses of K and variable addition of Na and Ca across different Na-Ca alteration assemblages. Na-Ca alteration has been well documented associated with the Jurassic arc. Previous studies demonstrated through mass balance, timing and spatial relationships, isotopic, and fluid inclusion studies that Na-Ca alteration associated with the Jurassic arc likely formed from the circulation of external, highly saline, non-magmatic fluids (e.g., Battles and Barton, 1995; Dilles et al., 1995). Na-Ca alteration documented in Laramide systems is generally similar to Na-Ca alteration documented along the Jurassic arc in mineral assemblages, compositions, and timing, but the volume of Na-Ca alteration in the Laramide systems is small as compared to the voluminous Na-Ca alteration documented in systems associated with the Jurassic arc.

Kinetic properties of the sodium-calcium exchanger in rat brain synaptosomes.

PubMed Central

Fontana, G; Rogowski, R S; Blaustein, M P

1995-01-01

1. The kinetic properties of the internal Na+ (Na+i)- dependent 45Ca2+ influx and external Na+ (Na+o)-dependent 45Ca2+ efflux were determined in isolated rat brain nerve terminals (synaptosomes) under conditions which the concentrations of internal Na+ ([Na+]i), external Na+ ([Na+]o), external Ca2+ (Ca2+]o), and external K+ ([K+]o) were varied. Both fluxes are manifestations of Na(+)-Ca2+ exchange. 2. Ca2+ uptake was augmented by raising [Na+]i and / or lowering [Na+]o. The increase in Ca2+ uptake induced by removing external Na+ was, in most instances, quantitatively equal to the Na+i-dependent Ca2+ uptake. 3. The Na+i-dependent Ca2+ uptake (measured at 1 s) was activated with an apparent half-maximal [Ca2+]o (KCa(o)) of about 0.23 mM. External Na+ inhibited the uptake in a non- competitive manner: increasing [Na+]o from 4.7 to 96 mM reduced the maximal Na+(i)-dependent Ca2+ uptake but did not affect KCa(o). 4. The inhibition of Ca2+ uptake by Na+o was proportional to ([Na+]o)2, and had a Hill coefficient (nH) of approximately 2.0. The mean apparent half-maximal [Na+]o for inhibition (KI(Na)) was about 60mM, and was independent of [Ca2+]o between 0.1 and 1.2mM; this, too, is indicative of non-competitive inhibition. 5. Low concentrations of alkali metal ions (M+) in the medium, including Na+, stimulated the Na+i-dependent uptake. The external Na+ and K+ concentrations required for apparent half-maximal activation (KM(Na) and KM(K), respectively) were 0.12 and 0.10mM. Thus, the relationship between Ca2+ uptake and [Na+]o was biphasic: uptake was stimulated by [Na+]o < or = 10 mM, and inhibited by higher [Na+]o. 6. The calculated maximal Na+i-dependent Ca2+ uptake (Jmax) was about 1530 pmol (mg protein) -1s-1 at 30 degrees C saturating [Ca2+]o and external M+ concentration ([M+]o), and with negligible inhibition by external Na+. 7. Internal Na+ activated the Ca2+ uptake with an apparent half-maximal concentration (KNa(i)) of about 20 mM and a Hill coefficient, nH, of approximately 3.0. 8. The Jmax for the Na+o-dependent efflux of Ca2+ from 45Ca(2+)-loaded synaptosomes treated with carbonyl cyanide p-trifluormethoxy-phenylhydrazone (FCCP) and caffeine (to release stored Ca2+ and raise the internal Ca2+ concentration ([Ca2+]i) was about 1800-2000 pmol (mg protein -1s-1 at 37 degrees C. 9. When the membrane potential (Vm) was reduced (depolarized) by increasing [K+]o, the Na+i-dependent Ca2+ influx increased, and the Na+o-dependent Ca2+ efflux declined. Both fluxes changed about 2-fold per 60 mV change in Vm. This voltage sensitivity corresponds to the movement of one elementary charge through about 60% of the membrane electric field. The symmetry suggests that the voltage-sensitive step is reversible. 10. The Jmax values for both Ca2P influx and efflux correspond to a Na+-Ca2+ exchange-mediated flux of about 425-575 jumol Ca2P (1 cell water)-' s-' or a turnover of about one quarter of the total synaptosome Ca2P in 1 s. We conclude that the Na+-Ca2P exchanger may contribute to Ca2P entry during nerve terminal depolarization; it is likely to be a major mechanism mediating Ca2P extrusion during subsequent repolarization and recovery. PMID:7666363

Electrochemical Synthesis of Core–Shell-Structured NbC–Fe Composite Powder for Enforcement in Low-Carbon Steel

PubMed Central

Song, Qiushi; Xu, Qian; Chen, Ying; Xu, Liang; Man, Tiannan

2017-01-01

An NbC–Fe composite powder was synthesized from an Nb2O5/Fe/C mixture by electrochemical reduction and subsequent carbonization in molten CaCl2–NaCl. The composite has a core–shell structure, in which NbC acts as the cores distributing in the Fe matrix. A strong bonding between NbC and Fe is benefit from the core–shell structure. The sintering and electrochemical reduction processes were investigated to probe the mechanism for the reactions. The results show that NbC particles about several nanometers were embraced by the Fe shell to form a composite about 100 nm in size. This featured structure can feasibly improve the wettability and sinterability of NbC as well as the uniform distribution of the carbide in the cast steel. By adding the composite into steel in the casting process, the grain size of the casted steel was markedly deceased from 1 mm to 500 μm on average, favoring the hardening of the casted steel. PMID:29104266

The role of impurity ions in the formation of phase composition of Norilsk ore types

NASA Astrophysics Data System (ADS)

Mashukov, Anatoly; Mashukova, Alla

2013-04-01

Using the methods of X-ray and Mössbauer spectroscopy, scanning electron microscopy, there were studied the samples of Norilsk ore types in order to identify compounds containing Cu and Ni. Depending on elemental composition there were singled out two sample series. Maximum concentration in percentage of selected elements for this series is presented below. 1: Ni (0), Cu (0,42), S (11,2), O (20,2), H (0.02), Fe(46,8), Ca (5,85), Mg (1,75), K (0,47), Na (0). 2: Ni (4,93), Cu (0), S (14,9), O (27,1), H (0,11), Fe (28,1), Ca (14,9), Mg (0), K (0), Na (1,61). The research conducted by using the method of scanning electron microscopy and the X-ray microanalysis showed that iron and sulfur are spread uniformly over the scanned area. Sulfur is absent in the inclusions containing Fe and Ni. There are areas, sizes 8 - 120 microns, strongly enriched by Fe. The inclusions of rectangular and rhomboid shapes sizes 8 - 15 microns contain Ni as the content of Fe increases. There were identified the inclusions having a high content of Cu, with a maximum concentration of Ni. The presence of native elements testifies to the reducing mode of ore formation processes. The phases, containing Cu ? Ni, have a complex composition: pentlandite (FeNiS2), chalcopyrite (CuFeS2), bornite (CuFeS4), nickelhexahydrite (NiSO4 [6H2O]), wroewolfeite (Cu4 (OH) 6 (SO4) • 2H2O), pyrrhotine (Fe7S8), pyrite (FeS2). The position of the absorption lines in the magnetically ordered areas indicates the presence of stoichiometric FeS and CuFeS2. Some of the samples of this group have broadened lines, indicating the existence of various positions of the Fe ions in the sublattices. The ingrowths of CuFeS2 are characterized by the degree of the structure defectiveness, by various impurities, which is reflected in the studied parameters. As regards the other sample series, containing FeS and CuFeS2 in pyrrhotine matrix of Fe 1-xSx, the spectra are the superposition of the unsolved doublet, which shows the presence of paramagnetic areas. The magnetic phase has the spectrum composed of two six-linear spectrums. The peaks on the spectrum borders show the oxide presence. The isomer shifts of the samples range from 0 to 1.394 mm/s, quadrupole splitting ranges from 0 to 2.688 mm/s. This indicates that the local electronic structure depends on the genesis of compounds. Thus, most of the bulk of Cu, Ni is not dissipated in the crystal lattices of the ore, but it is part of the ore sulphides. The presence of the characteristic structures of the solid solutions decomposition shows a wide temperature range of sulphide crystallization.

The phase diagrams of KCaF3 and NaMgF3 by ab initio simulations

NASA Astrophysics Data System (ADS)

Jakymiw, Clément; Vočadlo, Lidunka; Dobson, David P.; Bailey, Edward; Thomson, Andrew R.; Brodholt, John P.; Wood, Ian G.; Lindsay-Scott, Alex

2018-04-01

ABF3 compounds have been found to make valuable low-pressure analogues for high-pressure silicate phases that are present in the Earth's deep interior and that may also occur in the interiors of exoplanets. The phase diagrams of two of these materials, KCaF3 and NaMgF3, have been investigated in detail by static ab initio computer simulations based on density functional theory. Six ABF3 polymorphs were considered, as follows: the orthorhombic perovskite structure (GdFeO3-type; space group Pbnm); the orthorhombic CaIrO3 structure ( Cmcm; commonly referred to as the "post-perovskite" structure); the orthorhombic Sb2S3 and La2S3 structures (both Pmcn); the hexagonal structure previously suggested in computer simulations of NaMgF3 ( P63/ mmc); the monoclinic structure found to be intermediate between the perovskite and CaIrO3 structures in CaRhO3 ( P21/ m). Volumetric and axial equations of state of all phases considered are presented. For KCaF3, as expected, the perovskite phase is shown to be the most thermodynamically stable at atmospheric pressure. With increasing pressure, the relative stability of the KCaF3 phases then follows the sequence: perovskite → La2S3 structure → Sb2S3 structure → P63/ mmc structure; the CaIrO3 structure is never the most stable form. Above about 2.6 GPa, however, none of the KCaF3 polymorphs are stable with respect to dissociation into KF and CaF2. The possibility that high-pressure KCaF3 polymorphs might exist metastably at 300 K, or might be stabilised by chemical substitution so as to occur within the standard operating range of a multi-anvil press, is briefly discussed. For NaMgF3, the transitions to the high-pressure phases occur at pressures outside the normal range of a multi-anvil press. Two different sequences of transitions had previously been suggested from computer simulations. With increasing pressure, we find that the relative stability of the NaMgF3 phases follows the sequence: perovskite → CaIrO3 structure → Sb2S3 structure → P63/ mmc structure. However, only the perovskite and CaIrO3 structures are stable with respect to dissociation into NaF and MgF2.

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

NASA Astrophysics Data System (ADS)

Ferencz, Zs.; Szabados, M.; Varga, G.; Csendes, Z.; Kukovecz, Á.; Kónya, Z.; Carlson, S.; Sipos, P.; Pálinkó, I.

2016-01-01

A mechanochemical method (grinding the components without added water - dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution - wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic-inorganic nanocomposites: LDHs intercalated with amino acid anions.

The system Na2CO3-CaCO3 at 3 GPa

NASA Astrophysics Data System (ADS)

Podborodnikov, Ivan V.; Shatskiy, Anton; Arefiev, Anton V.; Rashchenko, Sergey V.; Chanyshev, Artem D.; Litasov, Konstantin D.

2018-04-01

It was suggested that alkali-alkaline earth carbonates may have a substantial role in petrological processes relevant to metasomatism and melting of the Earth's mantle. Because natrite, Na2CO3, Na-Ca carbonate (shortite and/or nyerereite), and calcite, CaCO3, have been recently reported from xenoliths of shallow mantle (110-115 km) origin, we performed experiments on phase relations in the system Na2CO3-CaCO3 at 3 GPa and 800-1300 °C. We found that the system has one intermediate compound, Na2Ca3(CO3)4, at 800 °C, and two intermediate compounds, Na2Ca(CO3)2 and Na2Ca3(CO3)4, at 850 °C. CaCO3 crystals recovered from experiments at 950 and 1000 °C are aragonite and calcite, respectively. Maximum solid solution of CaCO3 in Na2CO3 is 20 mol% at 850 °C. The Na-carbonate-Na2Ca(CO3)2 eutectic locates near 860 °C and 56 mol% Na2CO3. Na2Ca(CO3)2 melts incongruently near 880 °C to produce Na2Ca3(CO3)4 and a liquid containing about 51 mol% Na2CO3. Na2Ca3(CO3)4 disappears above 1000 °C via incongruent melting to calcite and a liquid containing about 43 mol% Na2CO3. At 1050 °C, the liquid, coexisting with Na-carbonate, contains 87 mol% Na2CO3. Na-carbonate remains solid up to 1150 °C and melts at 1200 °C. The Na2CO3 content in the liquid coexisting with calcite decreases to 15 mol% as temperature increases to 1300 °C. Considering the present and previous data, a range of the intermediate compounds on the liquidus of the Na2CO3-CaCO3 join changes as pressure increases in the following sequence: Na2Ca(CO3)2 (0.1 GPa) → Na2Ca(CO3)2, Na2Ca3(CO3)4 (3 GPa) → Na4Ca(CO3)3, Na2Ca3(CO3)4 (6 GPa). Thus, the Na2Ca(CO3)2 nyerereite stability field extends to the shallow mantle pressures. Consequently, findings of nyerereite among daughter phases in the melt inclusions in olivine from the sheared garnet peridotites are consistent with their mantle origin.

In Haitian women and preschool children, iron absorption from wheat flour-based meals fortified with sodium iron EDTA is higher than that from meals fortified with ferrous fumarate, and is not affected by Helicobacter pylori infection in children.

PubMed

Herter-Aeberli, Isabelle; Eliancy, Kerline; Rathon, Yanick; Loechl, Cornelia U; Marhône Pierre, Joseline; Zimmermann, Michael B

2017-08-01

Fe fortification of wheat flour was proposed in Haiti to combat Fe deficiency, but Fe bioavailability from fortificants has never been investigated in Haitian women or preschool children, two key target groups. We aimed to investigate the bioavailability of ferrous fumarate (FeFum), NaFeEDTA and their combination from fortified wheat flour. We recruited twenty-two healthy mother-child pairs in Port au Prince, Haiti, for an Fe-absorption study. We administered stable Fe isotopes as FeFum or NaFeEDTA individually in low-extraction wheat flour bread rolls consumed by all participants in a randomised, cross-over design. In a final, identical meal, consumed only by the women, FeFum+NaFeEDTA was administered. We measured Fe absorption by using erythrocyte incorporation of stable isotopes 14 d after consumption of each meal, and determined Fe status, inflammatory markers and Helicobacter pylori infection. Fe absorption (geometric mean was 9·24 (95 % CI 6·35, 13·44) and 9·26 (95 % CI 7·00, 12·31) from FeFum and 13·06 (95 % CI 9·23, 19·10) and 12·99 (95 % CI 9·18, 18·39) from NaFeEDTA in mothers and children, respectively (P<0·05 between compounds). Fe absorption from FeFum+NaFeEDTA was 11·09 (95 % CI 7·45, 17·34) and did not differ from the other two meals. H. pylori infection did not influence Fe absorption in children. In conclusion, in Haitian women and children, Fe absorption from NaFeEDTA was 40 % higher than from FeFum, and the combination FeFum+NaFeEDTA did not significantly increase Fe absorption compared with FeFum alone. In the context of Haiti, where the high costs of NaFeEDTA may not be affordable, the use of FeFum at 60 mg Fe/kg flour may be a preferable, cost-effective fortification strategy.

Thermodynamic modeling of phase relations and metasomatism in shear zones

NASA Astrophysics Data System (ADS)

Goncalves, P.; Oliot, E.; Marquer, D.

2009-04-01

Ductile shear zones have been recognized for a long time as privileged sites of intense fluid-rock interactions in the crust. In most cases they induce focused changes in mineralogy and bulk chemical composition (metasomatism) which in turn may control the deformation and fluid-migration processes. Therefore understanding these processes requires in a first step to be able to model phase relations in such open system. In this contribution, emphasizes in placed on metasomatic aspects of the problem. Indeed , in many ductile shear zones reported in metagranites, deformation and fluid-rock interactions are associated with gain in MgO and losses of CaO and Na2O (K2O is also a mobile component but it can be either gained or lost). Although the mineralogical consequences of this so-called Mg-metasomatism are well-documented (replacement of K-feldspar into phengite, breakdown of plagioclase into ab + ep, crystallization of chlorite), the origin of this coupled mass-transfer is still unknown. We have performed a forward modeling of phase relationships using petrogenetic grids and pseudosections that consider variations in chemical potential (μ) of the mobile elements (MgO, CaO, Na2O). Chemical potential gradients being the driving force of mass transfer, μ-μ diagrams are the most appropriate diagrams to model open systems where fluid-rock interactions are prominent. Chemical potential diagrams are equivalent to activity diagrams but our approach differs from previous work because (1) solid solutions are taken into account (2) phase relations are modeled in a more realistic chemical system (Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O) and (3) the use of pseudosections allows to predict changes of the mineralogy (modes, composition) for the specific bulk composition studied. A particular attention is paid to the relationships between component concentrations and chemical potentials, which is not obvious in multi-component system. The studied shear zone is located in the Grimsel granodiorite (Swiss Alps). Fourteen samples have been taken along a 80 meter-wide strain gradient from the undeformed granodiorite protolith to the ultramylonitic zone. The metastable magmatic assemblage consists of oligoclase (50 vol%), quartz ( 20 vol%), K-feldspar (17 vol%), and biotite (13 %). With increasing strain, K-feldspar and oligoclase rapidly disappear to produce albite and epidote porphyroblast (up to 45 and 5 vol% respectively) with phengite in shear planes (15 vol%). In the mylonite and ultramylonite, magmatic phases have been completely recrystallized and the metamorphic albite volume decreases down to 25 vol% whereas phengite constitutes up to 30 vol% of the rock. Epidote is absent in the ultramylonite. In localized shear bands, the metamorphic assemblage consists of phengite, chlorite, biotite and quartz. Mass balance calculations show that the ultramylonite is enriched in MgO (up to 130%) while CaO and Na2O are remove (80% and 45% respectively). However, mass transfer is even stronger in the chlorite-bearing shear bands, where CaO and Na2O have been completely leached out. Chemical potential pseudosections are constructed using the bulk composition of the unaltered granodiorite, with K2O, FeO, Al2O3 and SiO2 content remaining constant. Deformation occurred under water-saturated conditions at 6 kbar and 450°C. MgO, CaO and Na2O are considered as "perfectly mobile" components and therefore their chemical potentials, which is fixed by the externally-derived fluid, control the stability of the phases. μMgO vs μCaO and μMgO vs μNa2O diagrams, show that the breakdown of a Kf-ab-ep assemblage into phengite and the subsequent crystallization of chlorite require the introduction of a fluid with a μCaO and μNa2O significantly lower than in the unaltered metamorphic assemblage (Kf-ab-ep-Kf-Bio-q). Equalizing the chemical potential gradient of CaO and Na2O, established between the fluid and the metamorphic assemblage, is achieved by the complete removal of CaO and Na2O. The most striking result is that chemical potential diagram predicts that the loss of CaO and Na2O and the crystallization of chlorite-bearing assemblage at the expense of Kf-ep-ab imply a gain of MgO to reach equilibrium: "Mg-metasomatism" is therefore controlled and induced by the metamorphic assemblage. Finally fluid-rock interactions and mass transfer result in an increase in phyllosilicates in the shear zone from 13 to 32 vol%, which should strongly enhance the strain localization process. To conclude, our approach allows to predict and to quantify the mineralogical changes induced by fluid-rock interactions in a shear zone for any bulk composition or P-T composition.

Metamorphosed Plio-Pleistocene evaporites and the origins of hypersaline brines in the Salton Sea geothermal system, California: Fluid inclusion evidence

NASA Astrophysics Data System (ADS)

McKibben, Michael A.; Williams, Alan E.; Okubo, Susumu

1988-05-01

The Salton Sea geothermal system (SSGS) occurs in Plio-Pleistocene deltaic-lacustrine-evaporite sediments deposited in the Salton Trough, an active continental rift zone. Temperatures up to 365°C and hypersaline brines with up to 26 wt.% TDS are encountered at 1-3 km depth in the sediments, which are undergoing active greenschist facies hydrothermal metamorphism. Previous models for the origins of the Na-Ca-K-Cl brines have assumed that the high salinities were derived mainly from the downward percolation of cold, dense brines formed by low-temperature dissolution of shallow non-marine evaporites. New drillcores from the central part of the geothermal field contain metamorphosed, bedded evaporites at 1 km depth consisting largely of hornfelsic anhydrite interbedded with anhydrite-cemented solution-collapse shale breccias. Fluid inclusions trapped within the bedded and breccia-cementing anhydrite homogenize at 300°C (identical to the measured downhole temperature) and contain saline Na-Ca-K-Cl brines. Some of the inclusions contain up to 50 vol.% halite, sylvite and carbonate crystals at room temperature, and some halite crystals persist to above 300°C upon laboratory heating. The data are consistent with the trapping of halite-saturated Na-Ca-K-Cl fluids during hydrothermal metamorphism of the evaporites and accompanying solution collapse of interbedded shales. We conclude that many of the salt crystals in inclusions are the residuum of bedded evaporitic salt that was dissolved during metamorphism by heated connate fluids. Therefore, the high salinities of the Salton Sea geothermal brines are derived in part from the in situ hydrothermal metamorphism and dissolution of halides and CaSO 4 from relatively deeply-buried lacustrine evaporites. This fact places important constraints on modeling fluid-flow in the SSGS, as brines need not have migrated over great distances. The brines have been further modified to their present complex Na-Ca-K-Fe-Mn-Cl compositions by on-going sediment metamorphism and water-rock interaction.

Effects of Fe-Enrichment on the Equation of State and Stability of (Mg,Fe)SiO3 Perovskite and Post-Perovskite

NASA Astrophysics Data System (ADS)

Dorfman, S. M.; Holl, C. M.; Meng, Y.; Prakapenka, V.; Duffy, T. S.

2010-12-01

Fe-enrichment in the deep lower mantle has been proposed as an explanation for seismic anomalies such as large low shear velocity provinces (LLSVPs) and ultralow velocity zones (ULVZs). In order to resolve the effect of Fe on the stability and equation of state of the lower mantle’s dominant constituent, (Mg,Fe)SiO3 perovskite, we have studied Fe-rich natural orthopyroxenes, (Mg0.61Fe0.37Ca0.02)SiO3 and (Mg0.25Fe0.70Ca0.05)SiO3 (compositions determined by microprobe analysis), at lower mantle P-T conditions. Pyroxene starting materials were mixed with Au (pressure calibrant and laser absorber) and loaded with NaCl or Ne (pressure medium and thermal insulator) in a symmetric diamond anvil cell. X-ray diffraction experiments at pressures up to 122 GPa with in-situ laser heating were performed at the GSECARS (13-ID-D) and HPCAT (16-ID-B) sectors of the Advanced Photon Source. Heating samples to 2000 K produced single-phase orthorhombic GdFeO3-type perovskite at 63 GPa for the Mg# 61 composition and at 72 GPa for the Mg# 25 composition. At lower pressures (56 GPa for Mg# 61, 67 GPa for Mg# 25), heating both compositions resulted in a mixture of perovskite, SiO2 and (Mg,Fe)O. These measurements provide new constraints on the dependence of (Mg,Fe)SiO3 perovskite stability on pressure and composition. Upon further compression to 93 GPa and higher pressures with laser heating, Mg# 25 perovskite transformed to a two-phase mixture of perovskite and post-perovskite. This is consistent with previous findings that Fe substitution destabilizes (Mg,Fe)SiO3 perovskite relative to (Mg,Fe)SiO3 post-perovskite (Mao et al. 2004, Caracas and Cohen 2005). The bulk modulus at 80 GPa (K80) is ~550 GPa for both Fe-rich perovskites, comparable to values measured for MgSiO3 perovskite (Lundin et al. 2008). However, the volume of Fe-rich perovskites increases linearly with Fe-content. The (Mg0.25Fe0.70Ca0.05)SiO3 perovskite is 3% greater at 80 GPa than V80 for the Mg end-member, corresponding to a 20% density difference. This volume difference arises from variations in the a (2% larger than Fe-free perovskite) and c (1% larger) lattice parameters. Volumes under compression show no evidence of a discontinuity in the range measured; any magnetic spin transition in the Fe is either gradual or has too weak an effect on volume to be observed.

Elements and inorganic ions as source tracers in recent Greenland snow

NASA Astrophysics Data System (ADS)

Lai, Alexandra M.; Shafer, Martin M.; Dibb, Jack E.; Polashenski, Chris M.; Schauer, James J.

2017-09-01

Atmospheric transport of aerosols leads to deposition of impurities in snow, even in areas of the Arctic as remote as Greenland. Major ions (e.g. Na+, Ca2+, NH4+, K+, SO42-) are frequently used as tracers for common aerosol sources (e.g. sea spray, dust, biomass burning, anthropogenic emissions). Trace element data can supplement tracer ion data by providing additional information about sources. Although many studies have considered either trace elements or major ions, few have reported both. This study determined total and water-soluble concentrations of 31 elements (Al, As, Ca, Cd, Ce, Co, Cr, Dy, Eu, Fe, Gd, K, La, Mg, Mn, Na, Nb, Nd, Pb, Pr, S, Sb, Si, Sm, Sn, Sr, Ti, V, U, Y, Zn) in shallow snow pits at 22 sampling sites in Greenland, along a transect from Summit Station to sites in the northwest. Black carbon (BC) and inorganic ions were measured in colocated samples. Sodium, which is typically used as a tracer of sea spray, did not appear to have any non-marine sources. The rare earth elements, alkaline earth elements (Mg, Ca, Sr), and other crustal elements (Fe, Si, Ti, V) were not enriched above crustal abundances relative to Al, indicating that these elements are primarily dust sourced. Calculated ratios of non-sea salt Ca (nssCa) to estimated dust mass affirm the use of nssCa as a dust tracer, but suggest up to 50% uncertainty in that estimate in the absence of other crustal element data. Crustal enrichment factors indicated that As, Cd, Pb, non-sea-salt S, Sb, Sn, and Zn were enriched in these samples, likely by anthropogenic sources. Principal component analysis indicated more than one crustal factor, and a variety of factors related to anthropogenically enriched elements. Analysis of trace elements alongside major tracer ions does not change interpretation of ion-based source attribution for sources that are well-characterized by ions, but is valuable for assessing uncertainty in source attribution and identifying sources not represented by major ions.

Calcinaksite, KNaCa(Si4O10) H2O, a new mineral from the Eifel volcanic area, Germany

NASA Astrophysics Data System (ADS)

Chukanov, Nikita V.; Aksenov, Sergey M.; Rastsvetaeva, Ramiza K.; Blass, Günter; Varlamov, Dmitry A.; Pekov, Igor V.; Belakovskiy, Dmitry I.; Gurzhiy, Vladislav V.

2015-08-01

The new mineral calcinaksite, ideally KNaCa(Si4O10) · H2O, the first hydrous and Ca-dominant member of the litidionite group, is found in a xenolith of metamorphosed carbonate-rich rock from the southern lava flow of the Bellerberg volcano, Eastern Eifel region, Rheinland-Pfalz, Germany. It is associated with wollastonite, gehlenite, brownmillerite, Ca2SiO4 (larnite or calcio-olivine), quartz, aragonite, calcite, jennite, tobermorite and ettringite. Calcinaksite occurs as clusters of colourless to light-grey subhedral prismatic crystals. The mineral is brittle, with Mohs' hardness of 5; Dmeas is 2.62(2) g/cm3 and Dcalc is 2.623 g/cm3. The IR spectrum shows the presence of H2O molecules forming three different H-bonds. Calcinaksite is optically biaxial (+), α = 1.542(2), β = 1.550(2), γ = 1.565(3), 2 V meas = 75(10). The chemical composition (electron-microprobe data, H2O determined by the Alimarin method, wt%) is: Na2O 6.69, K2O 12.01, CaO 15.04, FeO 0.59, SiO2 61.46, H2O 4.9, total 100.69. The empirical formula is H2.11 K0.99Na0.84Ca1.04Fe0.03Si3.98O11. The crystal structure was solved and refined to R 1 = 0.053, wR 2 = 0.075 based upon 3057 reflections having I > 3σ( I). Calcinaksite is triclinic, space group P , a = 7.021(2), b = 8.250(3), c = 10.145(2) Å. α = 102.23(2)°, β = 100.34(2)°, γ = 115.09(3)°, V = 495.4(3) Å3, Z = 2. The strongest reflections of the X-ray powder pattern [ d, Å ( I,%) ( hkl)] are: 3.431 (70) (-121, -211, -210, 012, 0-22), 3.300 (67) (-031), 3.173 (95) (-103, -201, -220, 003, 111), 3.060 (100) (-212, 2-11, -221, 200, -1-13, 021, -202), 2.851 (83) (0-23, -122, 1-13, 1-31), 2.664 (62) (1-23, -222, 201).

Nanocompounds of iron and zinc: their potential in nutrition

NASA Astrophysics Data System (ADS)

Zimmermann, Michael B.; Hilty, Florentine M.

2011-06-01

Recent studies suggest nanostructured oxides and phosphates of Fe and atomically mixed Fe/Zn may be useful for nutritional applications. These compounds may have several advantages over existing fortificants, such as ferrous sulfate (FeSO4), NaFeEDTA and electrolytic iron. Because of their very low solubility and formation of soft agglomerates of micron size at neutral pH as well as their light native color, they tend to be less reactive in difficult-to-fortify foods and thus have superior sensory performance. At gastric pH the soft agglomerates break up and the Fe compounds rapidly and completely dissolve due to their very high surface area. This results in in vitro solubility and in vivo bioavailability comparable to FeSO4. Doping with Mg and/or Ca may increase solubility and improve sensory characteristics by lightening color. Feeding the nanostructured compounds at 150-400 µg Fe day-1 for 15 days to weanling rats in two studies did not induce measurable histological or biochemical adverse effects. No significant Fe was detected in the submucosa of the gastrointestinal tract or lymphatic tissues, suggesting that the nanosized Fe is absorbed through usual non-heme Fe absorption pathways. Thus, these novel compounds show promise as food fortificants or supplements.

Stabilization of Fe(0) nanoparticles with silica fume for enhanced transport and remediation of hexavalent chromium in water and soil.

PubMed

Li, Yongchao; Li, Tielong; Jini, Zhaohui

2011-01-01

Effective in situ remediation of Cr(VI) in groundwater requires the successful delivery of reactive iron particles to the subsurface. Fe(0) nanoparticles (20-110 nm diameter) supported on silica fume were synthesized by borohydride reduction of an aqueous iron salt in the presence of a support material. The experimental result showed that attachment of Fe(0) nanoparticles on the commercial available sub-micrometer silica fume prevented them from aggregation while maintaining the particle reactivity. When the Fe(0) concentration was 0.4 g/L, 88.00% of 40 mg/L Cr(VI) was removed by silica fume-supported Fe(0) nanoparticles (SF-Fe(0) in 120 min, 22.55% higher than unsupported Fe(0). Furthermore, transport experiments confirmed that almost all unsupported Fe(0) was retained, whereas 51.50% and 38.29% of SF-Fe(0) were eluted from the vertical and horizontal sand column, respectively. Additionally, the effect of solution ionic strength on the transport ability of SF-Fe(0) was evaluated. The result showed that increase in the salt concentration led to a decrease in the mobility and also the divalent ion Ca2+ had a greater effect than that of monovalent ion Na+.

Sensitive Determination of 6-Thioguanine Using Caffeic Acid-functionalized Fe3O4 Nanoparticles as an Electrochemical Sensor

NASA Astrophysics Data System (ADS)

Amir, Md.; Tunesi, Mawada M.; Soomro, Razium A.; Baykal, Abdülhadi; Kalwar, Nazar H.

2018-04-01

The study demonstrates the potential application of caffeic acid-functionalized magnetite nanoparticles (CA-Fe3O4 NPs) as an effective electrode modifying material for the electrochemical oxidation of the 6-thioguanine (6-TG) drug. The functionalized Fe3O4 NPs were prepared using simple wet-chemical methodology where the used caffeic acid acted simultaneously as growth controlling and functionalizing agent. The study discusses the influence of an effective functionalization on the signal sensitivity observed for the electro-oxidation of 6-TG over CA-Fe3O4 NPs in comparison to a glassy carbon electrode modified with bare and nicotinic acid (NA)-functionalized Fe3O4 NPs. The experiment results provided sufficient evidence to support the importance of favorable functionality to achieve higher signal sensitivity for the electro-oxidation of 6-TG. The presence of favorable interactions between the active functional moieties of caffeic acid and 6-TG synergized with the greater surface area of magnetic NPs produces a stable electro-oxidation signal within the working range of 0.01-0.23 μM with sensitive up to 0.001 μM. Additionally, the sensor showed the strong anti-interference potential against the common co-existing drug molecules such as benzoic acid, acetaminophen, epinephrine, norepinephrine, glucose, ascorbic acid and l-cysteine. In addition, the successful quantification of 6-TG from the commercial tablets obtained from local pharmacy further signified the practical capability of the discussed sensor.

Coexistence of Cu, Fe, Pb, and Zn oxides and chlorides as a determinant of chlorinated aromatics generation in municipal solid waste incinerator fly ash.

PubMed

Fujimori, Takashi; Tanino, Yuta; Takaoka, Masaki

2014-01-01

We investigated chemical determinants of the generation of chlorinated aromatic compounds (aromatic-Cls), such as polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs), in fly ash from municipal solid waste incineration. The influences of the following on aromatic-Cls formation in model fly ash (MFA) were systematically examined quantitatively and statistically: (i) inorganic chlorides (KCl, NaCl, CaCl2), (ii) base materials (SiO2, Al2O3, CaCO3), (iii) metal oxides (CuO, Fe2O3, PbO, ZnO), (iv) metal chlorides (CuCl2, FeCl3, PbCl2, ZnCl2), and (v) "coexisting multi-models." On the basis of aromatic-Cls concentrations, the ∑CBzs/∑PCBs ratio, and the similarity between distribution patterns, MFAs were categorized into six groups. The results and analysis indicated that the formation of aromatic-Cls depended strongly on the "coexistence condition", namely multimodels composed of not only metal chlorides, but also of metal oxides. The precise replication of metal chloride to oxide ratios, such as the precise ratios of Cu-, Fe-, Pb-, and Zn-chlorides and oxides, may be an essential factor in changing the thermochemical formation patterns of aromatic-Cls. Although CuCl2 acted as a promoter of aromatic-Cls generation, statistical analyses implied that FeCl3 also largely influenced the generation of aromatic-Cls under mixture conditions. Various additional components of fly ash were also comprehensively analyzed.

Chemical Weathering Records of Martian Soils Preserved in the Martian Meteorite EET79001

NASA Technical Reports Server (NTRS)

Rao, M. N.; Wentworth, S. J.; McKay, D. S.

2004-01-01

Impact-melt glasses, rich in Martian atmospheric gases, contain Martian soil fines (MSF) mixed with other coarse-grained regolith fractions which are produced during impact bombardment on Mars surface. An important characteristic of the MSF fraction is the simultaneous enrichment of felsic component accompanied by the depletion of mafic component relative to the host phase in these glasses. In addition, these glasses yield large sulfur abundances due to the occurrence of secondary mineral phases such as sulfates produced during acid-sulfate weathering of the regolith material near the Martian surface. Sulfurous gases released into atmosphere by volcanoes on Mars are oxidized to H2SO4 which deposit back on the surface of Mars as aerosol particles. Depending on the water availability, sulfuric acids dissolve into solutions which aggressively decompose the Fe-Mg silicates in the Martian regolith. During chemical weathering, structural elements such as Fe, Mg and Ca (among others) are released into the transgressing solutions. These solutions leach away the soluble components of Mg, Ca and Na, leaving behind insoluble iron as Fe3(+) hydroxysulfate mixed with poorly crystalline hydroxide- precipitates under oxidizing conditions. In this study, we focus on the elemental distribution of FeO and SO3 in the glass veins of EET79001, 507 sample, determined by Electron Microprobe and FE SEM measurements at JSC. This glass sample is an aliquot of a bigger glass inclusion ,104 analysed by where large concentrations of Martian atmospheric noble gases are found.

Installation and Implementation of a Comprehensive Groundwater Monitoring Program for the Indian Wells Valley, California

DTIC Science & Technology

2010-04-01

isotopes. Laboratory analysis for general chemistry included Na, Ca, Mg, K, Fe, Cl, HCO3, CO3 , SO4, F, B, NO3, arsenic (As), hardness, alkalinity...used for interpretations within the project. Prior to this effort, a single -location repository for isotopic data related to IWV investigations...canyons of importance to this study (Indian Wells Canyon, Freeman Canyon, and the upgradient canyons of Cow Haven, Sage, and Horse). Single samples

Enhanced magnetism of perovskite oxides, Sr(Sn,Fe)O3- δ , by substitution of nonmagnetic Ca and Ti ions

NASA Astrophysics Data System (ADS)

Nomura, Kiyoshi; Suzuki, Shigeyo; Mizunuma, Tomoya; Koike, Yuya; Okazawa, Atsushi

2017-11-01

Magnetic properties of perovskite oxides, SrSn1- x Fe x O3- δ ( x ≤ 0.15), substituted with nonmagnetic Ca and Ti ions were studied. XRD patterns showed the orthorhombic structure (close to tetragonal) of (Sr1- y Ca y )(Sn1- x Fe x )O3- δ and Sr(Sn1- x- y Fe x Ti y )O3- δ . The cell volumes decreased with the increase of Ca and Ti doping rates. Although Ti-substituted Sr(Sn, Fe)O3- δ showed small saturation magnetizations as compared with non-Ti substituted one, the magnetization increased a little with Ti doping rates up to 15%. On the other hand, all Ca-substituted Sr(Sn, Fe)O3- δ showed larger saturation magnetization than non-Ca substituted one. Two doublets of Fe3+ and a doublet of Fe4+ were observed in Mössbauer spectra of Ca-substituted Sr(Sn, Fe)O3- δ with weak ferromagnetism, and two sextets of high spin Fe3+ were additionally observed in Mössbauer spectra of Ca-doped Sr(Sn, Fe)O3- δ with relatively strong ferromagnetism. When Sr(Sn, Fe)O3- δ were further codoped with Ca and Ti ions, they showed the stable and enhanced ferromagnetic properties. It is considered that magnetic polarons among high spin Fe3+ species are overlapped by shrinking or deforming the crystal structure of perovskite oxides. That is the magnetism induced by a chemical pressure of perovskite oxides.

Thermobarometry of mafic igneous rocks based on clinopyroxene-liquid equilibria, 0 30 kbar

NASA Astrophysics Data System (ADS)

Putirka, K.; Johnson, Marie; Kinzler, Rosamond; Longhi, John; Walker, David

1996-02-01

Models for estimating the pressure and temperature of igneous rocks from co-existing clino-pyroxene and liquid compositions are calibrated from existing data and from new data obtained from experiments performed on several mafic bulk compositions (from 8 30 kbar and 1100 1475° C). The resulting geothermobarometers involve thermodynamic expressions that relate temperature and pressure to equilibrium constants. Specifically, the jadeite (Jd; NaAlSi2O6) diopside/hedenbergite (DiHd; Ca(Mg, Fe) Si2O6) exchange equilibrium between clinopyroxene and liquid is temperature sensitive. When compositional corrections are made to the calibrated equilibrium constant the resulting geothermometer is (i) 104 T=6.73-0.26* ln [Jdpx*Caliq*FmliqDiHdpx*Naliq*Alliq] -0.86* ln [MgliqMgliq+Feliq]+0.52*ln [Caliq] an expression which estimates temperature to ±27 K. Compared to (i), the equilibrium constant for jadeite formation is more sensitive to pressure resulting in a thermobarometer (ii) P=-54.3+299* T104+36.4* T104 ln [Jdpx[Siliq]2*Naliq*Alliq] +367*[Naliq*Alliq] which estimates pressure to ± 1.4 kbar. Pressure is in kbar, T is in Kelvin. Quantities such as Naliq represent the cation fraction of the given oxide (NaO0.5) in the liquid and Fm=MgO+FeO. The mole fractions of Jd and diopside+hedenbergite (DiHd) components are calculated from a normative scheme which assigns the lesser of Na or octahedral Al to form Jd; any excess AlVI forms Calcium Tschermak’s component (CaTs; CaAlAlSiO6); Ca remaining after forming CaTs and CaTiAl2O6 is taken as DiHd. Experimental data not included in the regressions were used to test models (i) and (ii). Error on predictions of T using model (i) is ±40 K. A pressure-dependent form of (i) reduces this error to ±30 K. Using model (ii) to predict pressures, the error on mean values of 10 isobaric data sets (0 25 kbar, 118 data) is ±0.3 kbar. Calculating thermodynamic properties from regression coefficients in (ii) gives VJd f of 23.4 ±1.3 cm3/mol, close to the value anticipated from bar molar volume data (23.5 cm3/mol). Applied to clinopyroxene phenocrysts from Mauna Kea, Hawaii lavas, the expressions estimate equilibration depths as great as 40 km. This result indicates that transport was sufficiently rapid that at least some phenocrysts had insufficient time to re-equilibrate at lower pressures.

Estimation of dietary intake and target hazard quotients for metals by consumption of wines from the Canary Islands.

PubMed

Gutiérrez, Angel J; Rubio, Carmen; Moreno, Isabel M; González, A Gustavo; Gonzalez-Weller, Dailos; Bencharki, Naouel; Hardisson, Arturo; Revert, Consuelo

2017-10-01

This paper describes the impact of mineral content on wines and assesses the potential health risk from consuming these wines from Canary Islands. The metal content (B, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Zn) of red wines belonging to different regions in the Canary Islands was determined by ICP-OES. The studied wine regions were Valle de la Orotava, Tacoronte-Acentejo, Ycoden-Daute-Isora, Abona and Valle de Güimar in Tenerife Island and only one in La Gomera and La Palma Islands. According to the content found, elements could be classified in two categories: the main group including Ca, K, Mg, Na, and the ''minor'' set consisting of B, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, Pb and Zn. Once calculated the metal intake through red wines consumption, we can conclude that Canarian drinkers are not exposed to unsafe levels of the metals studied, actually, the safety intake limits (daily) ranges between 0.9% in Zn and 2% in Cu, for normal drinkers. And also it has been demonstrated the good quality of Canarian red wines and there is no reason for health concern through the THQ calculation being the highest values determined in La Gomera wines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced Pb Absorption by Hordeum vulgare L. and Helianthus annuus L. Plants Inoculated with an Arbuscular Mycorrhizal Fungi Consortium.

PubMed

Arias, Milton Senen Barcos; Peña-Cabriales, Juan José; Alarcón, Alejandro; Maldonado Vega, María

2015-01-01

The effect of an arbuscular mycorrhizal fungi (AMF) consortium conformed by (Glomus intraradices, Glomus albidum, Glomus diaphanum, and Glomus claroideum) on plant growth and absorption of Pb, Fe, Na, Ca, and (32)P in barley (Hordeum vulgare L.) and sunflower (Helianthus annuus L.) plants was evaluated. AMF-plants and controls were grown in a substrate amended with powdered Pb slag at proportions of 0, 10, 20, and 30% v/v equivalent to total Pb contents of 117; 5,337; 13,659, and 19,913 mg Pb kg(-1) substrate, respectively. Mycorrhizal root colonization values were 70, 94, 98, and 90%, for barley and 91, 97, 95, and 97%, for sunflower. AMF inoculum had positive repercussions on plant development of both crops. Mycorrhizal barley absorbed more Pb (40.4 mg Pb kg(-1)) shoot dry weight than non-colonized controls (26.5 mg Pb kg(-1)) when treated with a high Pb slag dosage. This increase was higher in roots than shoots (650.0 and 511.5 mg Pb kg(-1) root dry weight, respectively). A similar pattern was found in sunflower. Plants with AMF absorbed equal or lower amounts of Fe, Na and Ca than controls. H. vulgare absorbed more total P (1.0%) than H. annuus (0.9%). The arbuscular mycorrizal consortium enhanced Pb extraction by plants.

Effects of hydrogen fugacity and confining pressure on the interdiffusion rate of NaSi-CaAl in plagioclase

NASA Astrophysics Data System (ADS)

Yund, Richard A.; Snow, Eleanour

1989-08-01

Average? values for NaSi-CaAl interdiffusion in the compositional interval from An0 to An26 have been determined at 1000°C by the method of lamellar homogenization. At 1500 MPa confining pressure (P), ? increases 1 order of magnitude (5.0×10-21 to 4.0×10-20 m2/s) for 4 orders of magnitude increase in hydrogen fugacity (0.029, Mn3O4-Mn2O3 buffer, to 197 MPa, FeO-Fe3O4 buffer). At constant hydrogen fugacity (fH2), ? increases rapidly at low pressure and becomes nearly independent of P above 1000 MPa. (For fH2 = 0.1 MPa, ? = 2.8 × 10-22 m2/s at P = 0.1 MPa, 5.0 × 10-21 at P = 500, 1.3×10-20 at P = 1000, and 1.4×10-20 at P = 1500). The dependence of ? on increasing pressure, when a hydrogen-related species is present, is believed to be due to an increase in the concentration of the structural defect associated with increase in the hydrogen impurity. In most crustal igneous rocks, which are internally buffered near quartz-fayalite-magnetite, the dependence of ? on fH2 is relatively minor compared to the effect of confining pressure.

Development of (177)Lu-DOTA-Dendrimer and Determination of Its Effect on Metal and Ion Levels in Tumor Tissue.

PubMed

Kovacs, Luciana; Tassano, Marcos; Cabrera, Mirel; Zamboni, Cibele B; Fernández, Marcelo; Anjos, Roberto M; Cabral, Pablo

2015-12-01

Dendrimers are synthetic nanomolecules with well-defined chemical structures. Different strategies have been used for radiolabeling dendrimers with different radioisotopes. In this study, the aim was to conjugate dendrimers with (177)Lu, to observe the in vivo behavior of the labeled compound and to measure the elementary changes in tumor tissue that could be caused by ionizing radiation. PAMAM G4 dendrimers conjugated with DOTA were labeled with (177)Lu. The radiolabeled compound was characterized and its stability was evaluated by reverse phase high performance liquid chromatography. Radiolabeling yield was >98% and stable for 24 hours. Biodistribution studies of (177)Lu-DOTA-dendrimers in C57BL/6 melanoma-bearing mice showed blood clearance with hepatic and renal depuration and tumor uptake. The concentrations of Br, Ca, Cl, Fe, K, Mg, Na, Rb, S, and Zn were determined in tumor tissues of C57BL/6 mice treated with (177)Lu-DOTA-dendrimers and in untreated mice. The results showed decreased concentrations of Br (62%), Ca (24%), Cl (51%), K (12%) and Na (60%) and increased concentrations of Fe (8%), Mg (28%), Rb (100%), S (6%) and Zn (4%) in tumor tissues of mice treated with (177)Lu-DOTA-dendrimers. These data may be useful to evaluate changes in tumor tissues as indicators of damage that could be caused by ionizing radiation.

Effect of cations (Na +, Ca 2+, Fe 3+) on the conductivity of a Nafion membrane

NASA Astrophysics Data System (ADS)

Hongsirikarn, Kitiya; Goodwin, James G.; Greenway, Scott; Creager, Stephen

It is known that trace amounts of cations have a detrimental effect on the liquid-phase conductivity of perfluorosulfonated membranes at room temperature. However, the conditions used were very different from typical fuel cell conditions. Recent research has shown the impact of conductivity measurement conditions on NH 4 + contaminated membranes. In this study, the impact of nonproton-containing cations (M n+ = Na +, Ca 2+, and Fe 3+) on Nafion membrane (N-211) conductivity was investigated both in deionized (DI) water at room temperature (∼25 °C) and in the gas phase at 80 °C under conditions similar to in a PEMFC. These conductivities were compared with those of Nafion membranes contaminated with NH 4 + ions. Under the same conditions, the conductivity of a metal cationic-contaminated membrane having the same proton composition (yH+m) was similar, but slightly lower than that of an NH 4 +-contaminated membrane. The conductivity in the purely H +-form of N-211 was more than 12 times greater than the M n+-form form at 25 °C in DI water. At 80 °C, the gas-phase conductivity was 6 times and 125 times greater at 100%RH and 30%RH, respectively. The quantitative results for conductivity and activation energy of contaminated membranes under typical fuel cell conditions are reported here for the first time.

ToF-SIMS applied to historical archaeology in the Alps

NASA Astrophysics Data System (ADS)

Sodhi, R. N. S.; Mahaney, W. C.; Milner, M. W.

2006-07-01

The actual route Hannibal followed during the invasion of Italia in the Second Punic War is one of the major questions of antiquity, one that historians/archaeologists have long studied. There are six possible passes Hannibal could have used and one of the many bits of evidence in the ancient literature that might help answer this question is the location of fired rock, the result of a conflagration Hannibal is reputed to have employed to reduce the size of boulders in a two-tier blocking rockslide on the lee side (e.g. Italian) some distance down from the high col. The only route with fired rock along the roadway leading to the Po River Valley or the Dora Riparia is below the Col du Clapier, one of the possible northern routes. ToF-SIMS investigation of the 100-μm thick burned crust in hornblende schist interlaced with veins of quartz-feldspathic minerals yields various elements C, Mg, Na, Ca, Si, Ti, P, Al, Fe and their associated fragments. Hydrocarbon fragments are thought to be products of combustion whereas Ca and Na along with Mg-Fe silicates are derived from the country rock. Aeolian components along with clay minerals settled onto rock surfaces following firing. While the SIMS data clearly would not provide an age for the burnt rock, compositional evidence of the conflagration may relate to Hannibal's actual route.

Determination of mineral, trace element, and pesticide levels in honey samples originating from different regions of Malaysia compared to manuka honey.

PubMed

Moniruzzaman, Mohammed; Chowdhury, Muhammed Alamgir Zaman; Rahman, Mohammad Abdur; Sulaiman, Siti Amrah; Gan, Siew Hua

2014-01-01

The present study was undertaken to determine the content of six minerals, five trace elements, and ten pesticide residues in honeys originating from different regions of Malaysia. Calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) were analyzed by flame atomic absorption spectrometry (FAAS), while sodium (Na) and potassium (K) were analyzed by flame emission spectrometry (FAES). Trace elements such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and cobalt (Co) were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) following the microwave digestion of honey. High mineral contents were observed in the investigated honeys with K, Na, Ca, and Fe being the most abundant elements (mean concentrations of 1349.34, 236.80, 183.67, and 162.31 mg/kg, resp.). The concentrations of the trace elements were within the recommended limits, indicating that the honeys were of good quality. Principal component analysis reveals good discrimination between the different honey samples. The pesticide analysis for the presence of organophosphorus and carbamates was performed by high performance liquid chromatography (HPLC). No pesticide residues were detected in any of the investigated honey samples, indicating that the honeys were pure. Our study reveals that Malaysian honeys are rich sources of minerals with trace elements present within permissible limits and that they are free from pesticide contamination.

Determination of Mineral, Trace Element, and Pesticide Levels in Honey Samples Originating from Different Regions of Malaysia Compared to Manuka Honey

PubMed Central

Moniruzzaman, Mohammed; Chowdhury, Muhammed Alamgir Zaman; Rahman, Mohammad Abdur; Sulaiman, Siti Amrah; Gan, Siew Hua

2014-01-01

The present study was undertaken to determine the content of six minerals, five trace elements, and ten pesticide residues in honeys originating from different regions of Malaysia. Calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) were analyzed by flame atomic absorption spectrometry (FAAS), while sodium (Na) and potassium (K) were analyzed by flame emission spectrometry (FAES). Trace elements such as arsenic (As), lead (Pb), cadmium (Cd), copper (Cu), and cobalt (Co) were analyzed by graphite furnace atomic absorption spectrometry (GFAAS) following the microwave digestion of honey. High mineral contents were observed in the investigated honeys with K, Na, Ca, and Fe being the most abundant elements (mean concentrations of 1349.34, 236.80, 183.67, and 162.31 mg/kg, resp.). The concentrations of the trace elements were within the recommended limits, indicating that the honeys were of good quality. Principal component analysis reveals good discrimination between the different honey samples. The pesticide analysis for the presence of organophosphorus and carbamates was performed by high performance liquid chromatography (HPLC). No pesticide residues were detected in any of the investigated honey samples, indicating that the honeys were pure. Our study reveals that Malaysian honeys are rich sources of minerals with trace elements present within permissible limits and that they are free from pesticide contamination. PMID:24982869

Total content and bioavailability of plant essential nutrients and heavy metals in top-soils of an industrialized area of Northwestern Greece

NASA Astrophysics Data System (ADS)

Barouchas, Pantelis; Avramidis, Pavlos; Salachas, Georgios; Koulopoulos, Athanasios; Christodoulopoulou, Kyriaki; Liopa-Tsakalidi, Aglaia

2017-04-01

Thirty surface soil samples from northwestern Greece in the Ptolemais-Kozani basin, were collected and analyzed for their total content in thirteen elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Cd, Cr, Cu, Ni, Pb, Zn) by ICP-AES and bioavailable content from a plant nutrition scope of view for (Ca, Fe, K, Mg, Mn, Na, P, Zn) by AAS and colorimetric techniques. Particle size distribution, Cation Exchange Capacity (CEC) and the magnetic susceptibility, in a low and a high frequency (at 47kHz and 0.47kHz), of soil samples were measured also in order to correlate the results. Total carbonates were tested by the pressure technique (BD Inventions, FOGII digital soil calcimeter). The concentrations of these elements were compared with international standards and guidelines. The results indicated that Cu, Cd, Zn and Pb are found enriched in the top soils of the study area, mainly as a consequence of natural processes from the surrounding rocks. Moreover, the bioavailability of some of these elements with a plant nutrition interest was tested and results indicate that they do not pose an immediate threat to the environment or crops as it all demonstrated values in an adequate range. Magnetic susceptibility in low and high frequency was correlated with clay content.

Ferromagnetic and photocatalytic behaviors observed in Ca-doped BiFeO3 nanofibres

NASA Astrophysics Data System (ADS)

Feng, Yan-Nan; Wang, Huan-Chun; Luo, Yi-Dong; Shen, Yang; Lin, Yuan-Hua

2013-04-01

Ca-doped BiFeO3 nanofibres have been fabricated by electrospinning method. Our results indicate that phase transition from space group R3c to C222 can be observed by the Ca doping. These BiFeO3 nanofibres show obvious room temperature ferromagnetic behaviors, and saturation magnetization can be enhanced with the Ca-doping concentration increasing, which could be correlated with the variation of the ratio of Fe2+/Fe3+ valence state. The BiFeO3 nanofibres show obvious photocatalytic performance and can be improved by the Ca-doping.

Calcium intercalation into layered fluorinated sodium iron phosphate

NASA Astrophysics Data System (ADS)

Lipson, Albert L.; Kim, Soojeong; Pan, Baofei; Liao, Chen; Fister, Timothy T.; Ingram, Brian J.

2017-11-01

The energy density and cost of battery systems, relative to the current state-of-the art, can be improved by developing alternative chemistries utilizing multivalent working ions such as calcium. Many challenges must be overcome, such as the identification of cathode materials with high energy density and an electrolyte with a wide electrochemical stability window that can plate and strip calcium metal, before market implementation. Herein, the feasibility and cycling performance of Ca2+ intercalation into a desodiated layered Na2FePO4F host is described. This is the first demonstration of Ca2+ intercalation into a polyanionic framework, which implies that other polyanionic framework materials may be active for Ca2+ intercalation. Although substantial effort is expected in order to develop a high energy density cathode material, this study demonstrates the feasibility of Ca2+ intercalation into multiple host structures types, thereby extending opportunities for development of Ca insertion host structures, suggesting such a cathode material can be identified and developed.

Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

2012-08-01

Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban Environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter <2.5 μm) resolved Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie FP7-EU framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the unique approach used is the simultaneous PIXE measurements at two monitoring sites: urban background (UB) and a street canyon traffic road site (RS). Elements related to primary non exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (secondary sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non exhaust brake dust (Fe-Cu) - 7%), and three types industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%). The validity of the PMF solution of the PIXE data is supported by strong correlations with external single particle mass spectrometry measurements. Beside apportioning the aerosol sources, some important air quality related conclusions can be drawn about the PM2.5 fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with industrial combustion emissions) is found a to be the major (82%) source of Cl in the urban agglomerate; (4) PM2.5 traffic brake dust (Fe-Cu) is mainly primarily emitted and not resuspended, whereas PM2.5 urban crustal dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing dust concentrations in road sites, far more effective than street sweeping activities.

Method for treating rare earth-transition metal scrap

DOEpatents

Schmidt, Frederick A.; Peterson, David T.; Wheelock, John T.; Jones, Lawrence L.

1992-12-29

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a prefused, rare earth fluoride-bearing flux of CaF.sub.2, CaCl.sub.2 or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy.

Method for treating rare earth-transition metal scrap

DOEpatents

Schmidt, F.A.; Peterson, D.T.; Wheelock, J.T.; Jones, L.L.

1992-12-29

Rare earth-transition metal (e.g., iron) scrap (e.g., Nd-Fe-B scrap) is flux (slag) remelted to reduce tramp non-metallic impurities, such as oxygen and nitrogen, and metallic impurities, such as Li, Na, Al, etc., picked up by the scrap from previous fabrication operations. The tramp impurities are reduced to concentrations acceptable for reuse of the treated alloy in the manufacture of end-use articles, such as permanent magnets. The scrap is electroslag or inductoslag melted using a rare earth fluoride-bearing flux of CaF[sub 2], CaCl[sub 2] or mixtures thereof or the slag resulting from practice of the thermite reduction process to make a rare earth-iron alloy. 3 figs.

THE INFLUENCE OF THE CHEMICAL NATURE OF SOLID PARTICLES ON THEIR CATAPHORETIC P.D. IN AQUEOUS SOLUTIONS

PubMed Central

Loeb, Jacques

1923-01-01

1. The effect of eight salts, NaCl, Na2SO4, Na4Fe(CN)6, CaCl2, LaCl3, ThCl4, and basic and acid fuchsin on the cataphoretic P.D. between solid particles and aqueous solutions was measured near the point of neutrality of water (pH 5.8). It was found that without the addition of electrolyte the cataphoretic P.D. between particles and water is very minute near the point of neutrality (pH 5.8), often less than 10 millivolts, if care is taken that the solutions are free from impurities. Particles which in the absence of salts have a positive charge in water near the point of neutrality (pH 5.8) are termed positive colloids and particles which have a negative charge under these conditions are termed negative colloids. 2. If care is taken that the addition of the salt does not change the hydrogen ion concentration of the solution (which in these experiments was generally pH 5.8) it can be said in general, that as long as the concentration of salts is not too high, the anions of the salt have the tendency to make the particles more negative (or less positive) and that cations have the opposite effect; and that both effects increase with the increasing valency of the ions. As soon as a maximal P.D. is reached, which varies for each salt and for each type of particles, a further addition of salt depresses the P.D. again. Aside from this general tendency the effects of salts on the P.D. are typically different for positive and negative colloids. 3. Negative colloids (collodion, mastic, Acheson's graphite, gold, and metal proteinates) are rendered more negative by low concentrations of salts with monovalent cation (e.g. Na) the higher the valency of the anion, though the difference in the maximal P.D. is slight for the monovalent Cl and the tetravalent Fe(CN)6 ions. Low concentrations of CaCl2 also make negative colloids more negative but the maximal P.D. is less than for NaCl; even LaCl3 increases the P.D. of negative particles slightly in low concentrations. ThCl4 and basic fuchsin, however, seem to make the negative particles positive even in very low concentrations. 4. Positive colloids (ferric hydroxide, calcium oxalate, casein chloride—the latter at pH 4.0) are practically not affected by NaCl, are rendered slightly negative by high concentrations of Na2SO4, and are rendered more negative by Na4Fe(CN)6 and acid dyes. Low concentrations of CaCl2 and LaCl3 increase the positive charge of the particles until a maximum is reached after which the addition of more salt depresses the P.D. again. 5. It is shown that alkalies (NaOH) act on the cataphoretic P.D. of both negative and positive particles as Na4Fe(CN)6 does at the point of neutrality. 6. Low concentrations of HCl raise the cataphoretic P.D. of particles of collodion, mastic, graphite, and gold until a maximum is reached, after which the P.D. is depressed by a further increase in the concentration of the acid. No reversal in the sign of charge of the particle occurs in the case of collodion, while if a reversal occurs in the case of mastic, gold, and graphite, the P.D. is never more than a few millivolts. When HCl changes the chemical nature of the colloid, e.g. when HCl is added to particles of amphoteric electrolytes like sodium gelatinate, a marked reversal will occur, on account of the transformation of the metal proteinate into a protein-acid salt. 7. A real reversal in the sign of charge of positive particles occurs, however, at neutrality if Na4Fe(CN)6 or an acid dye is added; and in the case of negative colloids when low concentrations of basic dyes or minute traces of ThCl4 are added. 8. Flocculation of the suspensions by salts occurs when the cataphoretic P.D. reaches a critical value which is about 14 millivolts for particles of graphite, gold, or mastic or denatured egg albumin; while for collodion particles it was about 16 millivolts. A critical P.D. of about 15 millivolts was also observed by Northrop and De Kruif for the flocculation of certain bacteria. PMID:19872064

Effects of NaBF4 + NaF on the Tensile and Impact Properties of Al-Si-Mg-Fe Alloys

NASA Astrophysics Data System (ADS)

Chen, Zongning; Wang, Tongmin; Zhao, Yufei; Zheng, Yuanping; Kang, Huijun

2015-05-01

NaBF4 + NaF were found to play three roles, i.e., Fe-eliminator, grain refiner, and eutectic modifier, in treating A356 alloy with a high Fe content. The joint effects led to significant improvement in both tensile and impact properties of thus treated alloy. The multiple reactions between the NaBF4 + NaF and Al-Si-Mg-Fe system are suggested to form Fe2B, AlB2, and Na in the melt, as per thermodynamic analysis. The three are responsible for Fe removal, grain refinement, and eutectic modification, respectively. When NaBF4 and NaF are mixed in weight ratio of 1:1, an optimum addition rate is in the range between 1.0 and 2.0 wt pct for treating AlSi7Mg0.3Fe0.65 alloy, based on the results of tensile and impact tests. Excessive addition of the salt may deteriorate the mechanical properties of the alloy, basically owing to overmodification of Si and contamination of salt inclusions.

Sorption, desorption, and speciation of Cd, Ni, and Fe by four calcareous soils as affected by pH.

PubMed

Tahervand, Samaneh; Jalali, Mohsen

2016-06-01

The sorption, desorption, and speciation of cadmium (Cd), nickel (Ni), and iron (Fe) in four calcareous soils were investigated at the pH range of 2-9. The results indicated that sorption of Fe by four soils was higher than 80 % at pH 2, while in the case of Cd and Ni was less than 30 %. The most common sequence of metal sorption at pH 2-9 for four soils was in the order of Fe ≫ Ni > Cd. Cadmium and Ni sorption as a function of pH showed the predictable trend of increasing metal sorption with increase in equilibrium pH, while the Fe sorption trend was different and characterized by three phases. With regard to the order of Cd, Ni, and Fe sorption on soils, Cd and Ni showed high affinity for organic matter (OM), whereas Fe had high tendency for calcium carbonate (CaCO3). Results of metal desorption using 0.01 M NaCl demonstrated that metal sorption on soils containing high amounts of CaCO3 was less reversible in comparison to soils containing high OM. In general, Cd and Ni desorption curves were characterized by three phases; (1) the greatest desorption at pH 2, (2) the low desorption at pH 3-7, and (3) the least desorption at pH > 7. The MINTEQ speciation solubility program showed that the percentage of free metals declined markedly with increase of pH, while the percentage of carbonate and hydroxyl species increased. Furthermore, MINTEQ predicted that saturation index (SI) of metals increased with increasing pH.

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.

Inorganic Macro- and Micronutrients in "Superberries" Black Chokeberries (Aronia melanocarpa) and Related Teas.

PubMed

Juranović Cindrić, Iva; Zeiner, Michaela; Mihajlov-Konanov, Darija; Stingeder, Gerhard

2017-05-18

Black chokeberries ( Aronia melanocarpa ) are considered to be functional food containing high amounts of anthocyanins, phenols, antioxidants, vitamins and minerals. Whereas organic compounds are well studied, there is little research on the mineral composition of the chokeberries. Thus, the presented study is focused on the determination of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Se, Sr and Zn in black chokeberry fruits and infusions to study the metals' extractability. The nutrients Ca, K and Mg are present in the fruits (dried matter) at g/kg level, whereas the other elements are present from µg/kg up to mg/kg level. The extraction yields of the metals from the infusion range from 4 (Al, Mn) up to 44% (Na). The toxic elements present do not pose any health risk when berries or infusions are consumed. Concluding, Aronia berries, as well as infusions derived from them, are a good dietary source of essential metals in addition to the organic compounds also contained.

Magnetism and electronic structures of novel layered CaFeAs{sub 2} and Ca{sub 0.75}(Pr/La){sub 0.25}FeAs{sub 2}

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

Huang, Yi-Na; Zou, Liang-Jian, E-mail: zou@theory.issp.ac.cn; University of Science and Technology of China, Hefei, Anhui 230026

2015-05-07

The magnetic and electronic properties of the parent material CaFeAs{sub 2} of new superconductors are investigated using first-principles calculations. We predict that the ground state of CaFeAs{sub 2} is a spin-density-wave (SDW)-type striped antiferromagnet driven by Fermi surface nesting. The magnetic moment around each Fe atom is about 2.1 μ{sub B}. We also present electronic and magnetic structures of electron-doped phase Ca{sub 0.75}(Pr/La){sub 0.25}FeAs{sub 2}, the SDW order was suppressed by La/Pr substitution. The As in arsenic layers is negative monovalent and acts as blocking layers enhancing two-dimensional character by increasing the spacing distance between the FeAs layers. This favorsmore » strong antiferromagnetic fluctuations mediated pairing, implying higher T{sub c} in Ca{sub 0.75}(Pr/La){sub 0.25}FeAs{sub 2} than Ca{sub 0.75}(Pr/La){sub 0.25}Fe{sub 2}As{sub 2}.« less

Phase relations of aluminous silica to 120 GPa and lowermost mantle dynamics

NASA Astrophysics Data System (ADS)

Tronnes, R. G.; Andrault, D.; Konopkova, Z.; Morgenroth, W.; Liermann, H.-P.

2012-04-01

Basalts have 3-10 times higher concentrations of Al, Ti, Ca and Na and more than 5 times lower concentration of Mg than peridotite. The resulting lower mantle basaltic mineralogy has no ferropericlase and low proportion of Mg-perovskite and post-perovskite with high Fe/Mg-ratio. Oversaturation of silica and alumina produces separate silica-dominated phases and Al-rich phases (NAL and Ca-ferrite phases). At pressures of 60-100 GPa common basalts crystallize 15-20% CaCl2-structured silica, 15-25% Ca-ferrite, 35-40% Mg-perovskite and 20-30% Ca-perovskite. The Fe-rich Mg-perovskite makes basaltic material denser than peridotite throughout the lower mantle below 720 km depth, with important implications for mantle dynamics. Partial separation of subducted basaltic crust from depleted lithosphere may occur within the strongly heterogeneous D" zone. The silica-dominated phases have considerable solubility of alumina [1]. At 3500-4000 K the transition from the CaCl2-phase to seifertite (a-PbO2-structure) of pure SiO2 occurs at 130-140 GPa, with a dp/dT-slope of about 10 MPa/K [2]. The transition pressure is reduced with Al-saturation. We investigated silica with 4 and 6 wt% alumina to 120 GPa, using LH-DAC at the Extreme Conditions Beamline (P02.2) at PETRA-III, DESY. Powdered glass mixed with 10-15 wt% Pt-powder was compressed and heated in NaCl pressure media in Re-gaskets. To delineate the phase transition, the samples were compressed incrementally with intermittent laser heating. Slow reaction rates required 20-40 min heating at 3500-4000 K for each heating step. The XRD data and pressure estimates were acquired repeatedly during heating and after quenching to room temperature. The first crystallization of seifertite at 3500-4000 K was recorded at about 118 and 108 GPa in samples with 4 and 6 wt% AlO1.5, respectively. The CaCl2-structured silica phase crystallized along with seifertite, consistent with a binary phase loop trending towards lower pressure with increasing Al-content. Due to the presence of the Al-rich Ca-ferrite phase (near the MgAl2O4-NaAlSiO4-join) in natural basaltic compositions, the Al-solubility limits for the silica-dominated phases in basaltic lithologies may be similar to those in the binary system SiO2-AlO1.5. Phase transitions in response to increasing pressure are generally associated with densification. Because of the strong partitioning of light and voluminous AlO1.5 into seifertite, however, the densification effect is more than offset by the lighter alumina component. The unit cell data of ref. [1] indicate a volume increase of about 3.8% associated with the transition. The associated density reduction would be strongly dependent on the substitution mechanism. O-vacancy and cation (3Si4+ → 4Al3+) substitutions yield density reductions of 5.4% and 1.9%, respectively [1]. The large density reduction accompanying the seifertite transition may limit the role of gravitational accretion of evolved MORB to the LLSVPs. Segregation of Fe-rich picritic, komatiitic or peridotitic rocks with no separate silica phase may be more likely. Deep-mantle cumulates and solidified melts of peridotitic to komatiitic composition were mostly produced in the Hadean and early Archean, indicating that the antipodal and near-equatorial LLSVPs, stabilized by Earth's rotation, could also represent ancient structures.

Structural analyses of Ca2+/CaM interaction with NaV channel C-termini reveal mechanisms of calcium-dependent regulation

PubMed Central

Wang, Chaojian; Chung, Ben C.; Yan, Haidun; Wang, Hong-Gang; Lee, Seok-Yong; Pitt, Geoffrey S.

2014-01-01

Ca2+ regulates voltage-gated Na+ (NaV) channels and perturbed Ca2+ regulation of NaV function is associated with epilepsy syndromes, autism, and cardiac arrhythmias. Understanding the disease mechanisms, however, has been hindered by a lack of structural information and competing models for how Ca2+ affects NaV channel function. Here, we report the crystal structures of two ternary complexes of a human NaV cytosolic C-terminal domain (CTD), a fibroblast growth factor homologous factor, and Ca2+/calmodulin (Ca2+/CaM). These structures rule out direct binding of Ca2+ to the NaV CTD, and uncover new contacts between CaM and the NaV CTD. Probing these new contacts with biochemical and functional experiments allows us to propose a mechanism by which Ca2+ could regulate NaV channels. Further, our model provides hints towards understanding the molecular basis of the neurologic disorders and cardiac arrhythmias caused by NaV channel mutations. PMID:25232683

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars.

PubMed

Sklute, Elizabeth C; Rogers, A Deanne; Gregerson, Jason C; Jensen, Heidi B; Reeder, Richard J; Dyar, M Darby

2018-03-01

Salts with high hydration states have the potential to maintain high levels of relative humidity (RH) in the near subsurface of Mars, even at moderate temperatures. These conditions could promote deliquescence of lower hydrates of ferric sulfate, chlorides, and other salts. Previous work on deliquesced ferric sulfates has shown that when these materials undergo rapid dehydration, such as that which would occur upon exposure to present day Martian surface conditions, an amorphous phase forms. However, the fate of deliquesced halides or mixed ferric sulfate-bearing brines are presently unknown. Here we present results of rapid dehydration experiments on Ca-, Na-, Mg- and Fe-chloride brines and multi-component (Fe 2 (SO 4 ) 3 ± Ca, Na, Mg, Fe, Cl, HCO 3 ) brines at ∼21°C, and characterize the dehydration products using visible/near-infrared (VNIR) reflectance spectroscopy, mid-infrared attenuated total reflectance spectroscopy, and X-ray diffraction (XRD) analysis. We find that rapid dehydration of many multicomponent brines can form amorphous solids or solids with an amorphous component, and that the presence of other elements affects the persistence of the amorphous phase under RH fluctuations. Of the pure chloride brines, only Fe-chloride formed an amorphous solid. XRD patterns of the multicomponent amorphous salts show changes in position, shape, and magnitude of the characteristic diffuse scattering observed in all amorphous materials that could be used to help constrain the composition of the amorphous salt. Amorphous salts deliquesce at lower RH values compared to their crystalline counterparts, opening up the possibility of their role in potential deliquescence-related geologic phenomena such as recurring slope lineae (RSLs) or soil induration. This work suggests that a wide range of aqueous mixed salt solutions can lead to the formation of amorphous salts and are possible for Mars; detailed studies of the formation mechanisms, stability and transformation behaviors of amorphous salts are necessary to further constrain their contribution to Martian surface materials.

Amorphous salts formed from rapid dehydration of multicomponent chloride and ferric sulfate brines: Implications for Mars

NASA Astrophysics Data System (ADS)

Sklute, Elizabeth C.; Rogers, A. Deanne; Gregerson, Jason C.; Jensen, Heidi B.; Reeder, Richard J.; Dyar, M. Darby

2018-03-01

Salts with high hydration states have the potential to maintain high levels of relative humidity (RH) in the near subsurface of Mars, even at moderate temperatures. These conditions could promote deliquescence of lower hydrates of ferric sulfate, chlorides, and other salts. Previous work on deliquesced ferric sulfates has shown that when these materials undergo rapid dehydration, such as that which would occur upon exposure to present day Martian surface conditions, an amorphous phase forms. However, the fate of deliquesced halides or mixed ferric sulfate-bearing brines are presently unknown. Here we present results of rapid dehydration experiments on Ca-, Na-, Mg- and Fe-chloride brines and multicomponent (Fe2(SO4)3 ± Ca, Na, Mg, Fe, Cl, HCO3) brines at ∼21 °C, and characterize the dehydration products using visible/near-infrared (VNIR) reflectance spectroscopy, mid-infrared attenuated total reflectance spectroscopy, and X-ray diffraction (XRD) analysis. We find that rapid dehydration of many multicomponent brines can form amorphous solids or solids with an amorphous component, and that the presence of other elements affects the persistence of the amorphous phase under RH fluctuations. Of the pure chloride brines, only Fe-chloride formed an amorphous solid. XRD patterns of the multicomponent amorphous salts show changes in position, shape, and magnitude of the characteristic diffuse scattering observed in all amorphous materials that could be used to help constrain the composition of the amorphous salt. Amorphous salts deliquesce at lower RH values compared to their crystalline counterparts, opening up the possibility of their role in potential deliquescence-related geologic phenomena such as recurring slope lineae (RSLs) or soil induration. This work suggests that a wide range of aqueous mixed salt solutions can lead to the formation of amorphous salts and are possible for Mars; detailed studies of the formation mechanisms, stability and transformation behaviors of amorphous salts are necessary to further constrain their contribution to Martian surface materials.

Cofortification of ferric pyrophosphate and citric acid/trisodium citrate into extruded rice grains doubles iron bioavailability through in situ generation of soluble ferric pyrophosphate citrate complexes.

PubMed

Hackl, Laura; Cercamondi, Colin I; Zeder, Christophe; Wild, Daniela; Adelmann, Horst; Zimmermann, Michael B; Moretti, Diego

2016-05-01

Iron fortification of rice is a promising strategy for improving iron nutrition. However, it is technically challenging because rice is consumed as intact grains, and ferric pyrophosphate (FePP), which is usually used for rice fortification, has low bioavailability. We investigated whether the addition of a citric acid/trisodium citrate (CA/TSC) mixture before extrusion increases iron absorption in humans from FePP-fortified extruded rice grains. We conducted an iron absorption study in iron-sufficient young women (n = 20), in which each participant consumed 4 different meals (4 mg Fe/meal): 1) extruded FePP-fortified rice (No CA/TSC); 2) extruded FePP-fortified rice with CA/TSC added before extrusion (CA/TSC extruded); 3) extruded FePP-fortified rice with CA/TSC solution added after cooking and before consumption (CA/TSC solution); and 4) nonextruded rice fortified with a FeSO4 solution added after cooking and before consumption (reference). Iron absorption was calculated from erythrocyte incorporation of stable iron isotopes 14 d after administration. In in vitro experiments, we assessed the soluble and dialyzable iron from rice meals in which CA/TSC was added at different preparation stages and from meals with different iron:CA:TSC ratios. Fractional iron absorption was significantly higher from CA/TSC-extruded meals (3.2%) than from No CA/TSC (1.7%) and CA/TSC solution (1.7%; all P < 0.05) and was not different from the FeSO4 reference meal (3.4%). In vitro solubility and dialyzability were higher in CA/TSC-extruded rice than in rice with No CA/TSC and CA/TSC solution, and solubility increased with higher amounts of added CA and TSC in extruded rice. Iron bioavailability nearly doubled when CA/TSC was extruded with FePP into fortified rice, resulting in iron bioavailability comparable to that of FeSO4 We attribute this effect to an in situ generation of soluble FePP citrate moieties during extrusion and/or cooking because of the close physical proximity of FePP and CA/TSC in the extruded rice matrix. This trial was registered at clinicaltrials.gov as NCT02176759. © 2016 American Society for Nutrition.

Electrically induced fluorescence Fe3+ sensing behavior of nanostructured Tiron doped polypyrrole.

PubMed

Tavoli, Farnaz; Alizadeh, Naader

2016-11-23

Nanostructured polypyrrole (PPy) film doped with Tiron was electrodeposited from aqueous solution on the surface of transparent electrode and used for sensitive, selective and rapid electrically controlled fluorescence detection of Fe 3+ in aqueous media. The fluorescence intensity of PPy-Tiron film decreases linearly in the presence of Fe 3+ by applying negative potential over a concentration range from 5.0 × 10 -8 to 1.0 × 10 -6  mol L -1 , with a relatively fast response time of less than 30 s at pH 7.4. The detection is not affected by the coexistence of other competitive metal ions such as Al 3+ , Ce 3+ , Tl 3+ , La 3+ , Bi 3+ , Cr 2+ , Mn 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ , Pb 2+ , Na + , K + , Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ . The proposed electro-fluorescence sensor has a potential application to the determination of Fe 3+ in environmental and biological systems. The fluorescent thin film sensor was also used as a novel probe for Fe 3+ /Fe 2+ speciation in aqueous solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical abundances of globular clusters in NGC 5128 (Centaurus A)

NASA Astrophysics Data System (ADS)

Hernandez, Svea; Larsen, Søren; Trager, Scott; Kaper, Lex; Groot, Paul

2018-06-01

We perform a detailed abundance analysis on integrated-light spectra of 20 globular clusters (GCs) in the early-type galaxy NGC 5128 (Centaurus A). The GCs were observed with X-Shooter on the Very Large Telescope (VLT). The cluster sample spans a metallicity range of -1.92 < [Fe/H] < -0.13 dex. Using theoretical isochrones, we compute synthetic integrated-light spectra and iterate the individual abundances until the best fit to the observations is obtained. We measured abundances of Mg, Ca, and Ti, and find a slightly higher enhancement in NGC 5128 GCs with metallicities [Fe/H] < -0.75 dex, of the order of ˜0.1 dex, than in the average values observed in the Milky Way (MW) for GCs of the same metallicity. If this α-enhancement in the metal-poor GCs in NGC 5128 is genuine, it could hint at a chemical enrichment history different than that experienced by the MW. We also measure Na abundances in 9 out of 20 GCs. We find evidence for intracluster abundance variations in six of these clusters where we see enhanced [Na/Fe] > +0.25 dex. We obtain the first abundance measurements of Cr, Mn, and Ni for a sample of the GC population in NGC 5128 and find consistency with the overall trends observed in the MW, with a slight enhancement (<0.1 dex) in the Fe-peak abundances measured in the NGC 5128.

A chemically activated graphene-encapsulated LiFePO4 composite for high-performance lithium ion batteries.

PubMed

Ha, Jeonghyun; Park, Seung-Keun; Yu, Seung-Ho; Jin, Aihua; Jang, Byungchul; Bong, Sungyool; Kim, In; Sung, Yung-Eun; Piao, Yuanzhe

2013-09-21

A composite of modified graphene and LiFePO4 has been developed to improve the speed of charging-discharging and the cycling stability of lithium ion batteries using LiFePO4 as a cathode material. Chemically activated graphene (CA-graphene) has been successfully synthesized via activation by KOH. The as-prepared CA-graphene was mixed with LiFePO4 to prepare the composite. Microscopic observation and nitrogen sorption analysis have revealed the surface morphologies of CA-graphene and the CA-graphene/LiFePO4 composite. Electrochemical properties have also been investigated after assembling coin cells with the CA-graphene/LiFePO4 composite as a cathode active material. Interestingly, the CA-graphene/LiFePO4 composite has exhibited better electrochemical properties than the conventional graphene/LiFePO4 composite as well as bare LiFePO4, including exceptional speed of charging-discharging and excellent cycle stability. That is because the CA-graphene in the composite provides abundant porous channels for the diffusion of lithium ions. Moreover, it acts as a conducting network for easy charge transfer and as a divider, preventing the aggregation of LiFePO4 particles. Owing to these properties of CA-graphene, LiFePO4 could demonstrate enhanced and stably long-lasting electrochemical performance.

Determination of bioavailable macro- and microelements from agricultural soil using different extractants

NASA Astrophysics Data System (ADS)

Milićević, Tijana; Relić, Dubravka; Popović, Aleksandar

2015-04-01

Translocation of elements from soil to plant has a major impact on the growing plants and on their quality in any agricultural field. In this study, soil samples were collected from agricultural area Radmilovac, Serbia during grapevine season in 2013. Bioavailable elements from soil to plant (grapevine) were isolated by five different extractants: 0.11 mol L-1 CH3COOH, 0.05 mol L-1 Na-EDTA, 0.01 mol L-1 CaCl2, 1 mol L-1 NH4NO3 and distilled water during 2 and 16 h. Concentrations of 22 bioavailable macroelements: Al, Ca, Fe, K, Mg, Mn, Na, P, S, Si and microelements: B, Be, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V, Zn were determined by ICP-OES. The best extractant for Al, B, Be, Mg, Mo, Si and Zn was CH3COOH, Na-EDTA for Ca, Cd, Co, Cu, Fe, K, Mn, Ni, P, Pb, V, and distilled water for Na and S. Acetic acid has been proven to be an aggressive extractant and it can be used for isolation of higher concentrations of plant bioavailable elements from soil, rather than distilled water, CaCl2 and NH4NO3. The acidity of CH3COOH enhances the extraction of bioavailable fraction of microelements from various substrates and destruction of carbonates as well. However, it can be concluded that there is no unique extractant for isolation of the most bioavailable fraction for all elements from the soil. It can be noticed that the most common concentrations of macroelements, K and Mn, are in correlation with concentrations of microelements, Cd, Co, Ni and Zn. This indicates that the most of their concentrations in soils are followed by microelements, whose concentrations are much lower than concentrations of macroelements. However, as these correlations are the most common, it can be concluded that the pairs of macro- and microelements (e.g. Mn-Cd, Mn-Co, Ni-Cd, Ni-Co, Ni-Mn, Zn-Cd, Zn-Co, Zn-Mn, Zn-Ni) have the same source in soil and can be isolated by the same extractant. It is interesting to note that the concentrations of Ca and Mg extracted from soil using CH3COOH are in correlation and that neither of these macroelements is in correlation with the concentration of microelements isolated with the same extractant. The concentrations of Cu and S extracted from soil by distilled water during 16 h are in correlation. These elements could have entered only through the soil surface layer while grapevines were primarily treated by fungicide copper(II)-sulphate. In addition, the concentration of S is correlated with the concentrations of Mn, P and Na. It can be assumed that the correlation between these elements points to their origin from the pesticides used in agriculture production.

Automated spectroscopic abundances of A and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE

NASA Astrophysics Data System (ADS)

Erspamer, D.; North, P.

2003-02-01

Using the method presented in Erspamer & North (\\cite{erspamer}, hereafter Paper I), detailed abundances of 140 stars are presented. The uncertainties characteristic of this method are presented and discussed. In particular, we show that for a S/N ratio higher than 200, the method is applicable to stars with a rotational velocity as high as 200 km s-1. There is no correlation between abundances and Vsin i, except a spurious one for Sr, Sc and Na which we explain by the small number of lines of these elements combined with a locally biased continuum. Metallic giants (Hauck \\cite{hauck}) show larger abundances than normal giants for at least 8 elements: Al, Ca, Ti, Cr, Mn, Fe, Ni and Ba. The anticorrelation for Na, Mg, Si, Ca, Fe and Ni with Vsin i suggested by Varenne & Monier (\\cite{varenne99}) is not confirmed. The predictions of the Montréal models (e.g. Richard et al. \\cite{richard01}) are not fulfilled in general. However, a correlation between left [(Fe)/(H)right ] and log g is found for stars of 1.8 to 2.0 M_sun. Various possible causes are discussed, but the physical reality of this correlation seems inescapable. Based on observations collected at the 1.93 m telescope at the Observatoire de Haute-Provence (St-Michel l'Observatoire, France) and CORALIE. Based on observations collected at the Swiss 1.2 m Leonard Euler telescopes at the European Southern Observatory (La Silla, Chile). Tables 5 and 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u.strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/398/1121

Characterization of Italian honeys (Marche Region) on the basis of their mineral content and some typical quality parameters

PubMed Central

Conti, Marcelo Enrique; Stripeikis, Jorge; Campanella, Luigi; Cucina, Domenico; Tudino, Mabel Beatriz

2007-01-01

Background The characterization of three types of Marche (Italy) honeys (Acacia, Multifloral, Honeydew) was carried out on the basis of the their quality parameters (pH, sugar content, humidity) and mineral content (Na, K, Ca, Mg, Cu, Fe, and Mn). Pattern recognition methods such as principal components analysis (PCA) and linear discriminant analysis (LDA) were performed in order to classify honey samples whose botanical origins were different, and identify the most discriminant parameters. Lastly, using ANOVA and correlations for all parameters, significant differences between diverse types of honey were examined. Results Most of the samples' water content showed good maturity (98%) whilst pH values were in the range 3.50 – 4.21 confirming the good quality of the honeys analysed. Potassium was quantitatively the most relevant mineral (mean = 643 ppm), accounting for 79% of the total mineral content. The Ca, Na and Mg contents account for 14, 3 and 3% of the total mineral content respectively, while other minerals (Cu, Mn, Fe) were present at very low levels. PCA explained 75% or more of the variance with the first two PC variables. The variables with higher discrimination power according to the multivariate statistical procedure were Mg and pH. On the other hand, all samples of acacia and honeydew, and more than 90% of samples of multifloral type have been correctly classified using the LDA. ANOVA shows significant differences between diverse floral origins for all variables except sugar, moisture and Fe. Conclusion In general, the analytical results obtained for the Marche honeys indicate the products' high quality. The determination of physicochemical parameters and mineral content in combination with modern statistical techniques can be a useful tool for honey classification. PMID:17880749

Mineral Systems, Their Types, and Distribution in Nature: 2. Products of Contemporary Fumarole Activity at Tolbachik Volcano (Russia) and Vulcano (Italy)

NASA Astrophysics Data System (ADS)

Krivovichev, V. G.; Charykova, M. V.

2017-12-01

The number of mineral species in which a certain chemical element is species-defining (according to statistical data up to 2015) has been specified. Seventy chemical elements are species-defining for 5044 minerals. The following chemical elements lead in the composition of minerals (number of mineral species in parentheses): oxygen (4115), hydrogen (2800), silicon (1471), calcium (1167), sulfur (1056), aluminium (985), sodium (949), iron (945), copper (636), phosphorus (597), arsenic (594), and magnesium (571). The distribution of mineral species by various systems in the products of contemporary fumarole activity at two volcanoes, Tolbachik in Kamchatka, Russia, and Vulcano in Sicily, Italy, has been compared. These locations were also compared for the distribution of species-defining elements. Thus, it has been determined that in fumaroles of both volcanoes, Tl, S, Cl, F and Na are "excessive," present in minerals in elevated amounts, whereas H, Ca, Fe, and Mn are "deficient." The abundance of Cu, Se, V, Mg, Zn, As, and F in minerals at Tolbachik is higher than the global mean values of these elements in the Earth's crust, whereas the abundance is significantly lower at Vulcano. Sn, I, Br, K, Pb, Al, Fe, and Bi demonstrate the opposite behavior. Comparison of the Yadovitaya and Arsenatnaya fumaroles at the Tolbachik volcano showed that the products of the former are richer in H, Cl, Cu, S, K, O, Al, Fe, and Pb, and poorer in As, Ca, Mg, and Na as species-defining elements. In addition, V-and Mo-bearing minerals are found only at Yadovitaya, whereas minerals containing F, Ti, B, Te, and Zn are known only at Arsenatnaya.

Investigation of sodium insertion–extraction in olivine Na x FePO 4 (0 ≤ x ≤ 1) using first-principles calculations

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

Saracibar, A.; Carrasco, J.; Saurel, D.

Olivine NaFePO4 has recently attracted the attention of the scientific community as a promising cathode material for Na-ion batteries. In this work we combine density functional theory (DFT) calculations and high resolution synchrotron X-ray diffraction (HRXRD) experiments to study the phase stability of NaxFePO4 along the whole range of sodium compositions (0 ≤ x ≤ 1). DFT calculations reveal the existence of two intermediate structures governing the phase stability at x = 2/3 and x = 5/6. This is in contrast to isostructural LiFePO4, which is a broadly used cathode in Li-ion batteries. Na2/3FePO4 and Na5/6FePO4 ground states both alignmore » vacancies diagonally within the ab plane, coupled to a Fe2+/Fe3+ alignment. HRXRD data for NaxFePO4 (2/3 < x < 1) materials show common superstructure reflections up to x = 5/6 within the studied compositions. The computed intercalation voltage profile shows a voltage difference of 0.16 V between NaFePO4 and Na2/3FePO4 in agreement with the voltage discontinuity observed experimentally during electrochemical insertion.« less

Binder-jetting 3D printing and alloy development of new biodegradable Fe-Mn-Ca/Mg alloys.

PubMed

Hong, Daeho; Chou, Da-Tren; Velikokhatnyi, Oleg I; Roy, Abhijit; Lee, Boeun; Swink, Isaac; Issaev, Ilona; Kuhn, Howard A; Kumta, Prashant N

2016-11-01

3D printing of various biomaterials including titanium and stainless steel has been studied for treating patients with cranio-maxillofacial bone defect. The potential long term complications with use of inert biometals have opened the opportunities for use of biodegradable metals in the clinical arena. The authors previously reported that binder-jet 3D printing technique enhanced the degradation rates of biodegradable Fe-Mn alloy by creating engineered micropores rendering the system attractive as biodegradable implantable devices. In the present study, the authors employed CALPHAD modeling to systematically study and modify the Fe-Mn alloy composition to achieve enhanced degradation rates. Accordingly, Ca and Mg addition to Fe-35wt% Mn solid solution predicted increase in degradation rates. In order to validate the CALPHAD results, Fe - (35-y)wt% Mn - ywt% X (X=Ca, Mg, and y=0, 1, 2) were synthesized by using high energy mechanical alloying (HEMA). Sintered pellets of Fe-Mn-Ca and Fe-Mn-Mg were then subjected to potentiodynamic polarization (PDP) and live/dead cell viability tests. Sintered pellets of Fe-Mn, Fe-Mn-Ca, and Fe-Mn-Mg also exhibited MC3T3 murine pre-osteoblast cells viability in the live/dead assay results. Fe-Mn and Fe-Mn-1Ca were thus accordingly selected for 3D printing and the results further confirmed enhanced degradation of Ca addition to 3D printed constructs validating the theoretical and alloy development studies. Live/dead and MTT cell viability results also confirmed good cytocompatibility of the 3D-printed Fe-Mn and Fe-Mn-1Ca constructs. Bone grafting is widely used for the treatment of cranio-maxillofacial bone injuries. 3D printing of biodegradable Fe alloy is anticipated to be advantageous over current bone grafting techniques. 3D printing offers the fabrication of precise and tailored bone grafts to fit the patient specific bone defect needs. Biodegradable Fe alloy is a good candidate for 3D printing synthetic grafts to regenerate bone tissue without eliciting complications. CALPHAD theoretical models were used to develop new Fe-Mn-Ca/Mg alloys to enhance the degradation rates of traditional Fe-Mn alloys. In vitro experimental results also showed enhanced degradation rates and good cytocompatibility of sintered Fe-Mn-Ca/Mg compacts. 3D printing of Fe-Mn and Fe-Mn-1Ca alloys further demonstrated their feasibility as potentially viable bone grafts for the future. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The Giant Branch of omega Centauri. IV. Abundance Patterns Based on Echelle Spectra of 40 Red Giants

NASA Astrophysics Data System (ADS)

Norris, John E.; Da Costa, G. S.

1995-07-01

Abundances of some 20 elements have been determined for a (biased) sample of 40 red giants having Mv < -1.5 in the chemically inhomogeneous globular cluster ω Centauri. The results are based on high-resolution, high signal-to-noise echelle spectra and permit one to examine the roles of primordial enrichment and stellar evolutionary mixing effects in the cluster. Our basic conclusions are as follows (1) There is an abundance range -1.8 < [Fe/H] < -0.8, and even more metal rich stars may exist in the cluster. (2) For the α (Mg, Si, Ca, Ti) and iron peak (Cr, Ni) elements and Sc and V, [metal/Fe] is flat as a function of [Fe/H] and is consistent with primordial enrichment from stars having mass greater than 10 Msun, as has been found for field halo stars. (3) There is a large scatter in the abundances of C, N, and 0. The bulk of the stars have -0.9 < [C/Fe] < -0.3 and [O/Fe] ˜ 0.3, as is found at the red giant branch tip in other "normal" (showing no spread in [Fe/H]) clusters of similar abundance, while there also exists a group of CN-strong stars having [C/Fe] ˜ -0.7 and [O/Fe] ˜ -0.5. Nitrogen appears to be enhanced in all of these carbon-depleted stars. These results are most readily explained in terms of evolutionary mixing effects not predicted by standard stellar evolution calculations and are consistent with the earlier suggestions of Cohen & Bell (1986) and Paltoglou & Norris (1989) concerning processing in both the CN and ON cycles in the stars being observed. In contrast, the group of CO-strong stars first identified by Persson et al. (1980) has [C/Fe] ˜ 0.0, [O/Fe] ˜ 0.4, and [N/Fe] ˜ 0.4 (or 0.9 if the nitrogen scale of Brown and Wallerstein is correct) and is suggestive of primordial enrichment of carbon and/or nitrogen from intermediate- and possibly low-mass stars, tempered by later stellar evolutionary effects. (4) [Na/Fe] and [Al/Fe] are anticorrelated with [O/Fe], and there is a positive correlation between [Na/Fe] and [Al/Fe], all of which are most readily explained in terms of evolutionary mixing effects as first suggested by Denisenkov & Denisenkova (1990). Such an explanation is supported by the similar ([Na/Fe], [O/Fe]) anticorrelation reported by Kraft et al. (1993) in the "normal" globular clusters. (5) For the heavy neutron-addition elements (in particular Y, Ba, La, and Nd) [heavy metal/Fe] rises as [Fe/H] increases, in sharp contrast with what is found in the "normal" clusters, while the relative abundances as a function of atomic number are suggestive of s-processing. The increase in [heavy metal/Fe] with [Fe/H] appears independent of the abundance of C, N, O, Na and Al and is most naturally explained as a primordial effect. Guided by the predictions of existing (somewhat uncertain) stellar evolution calculations, we suggest that this results from primordial enrichment from stars having mass as low as 1-3 Msun. (6) If the preceding suggestion is correct, chemical enrichment in ω Cen occurred over an extended period, perhaps ≥1 Gyr.

STM/STS study of superconducting properties in Ca10(Pt4As8)(Fe2As2)5

NASA Astrophysics Data System (ADS)

Kim, Jisun; Nam, Hyoungdo; Li, Guorong; Karki, Amar; Shih, Chih-Kang; Zhang, Jiandi; Jin, Rongying; Plummer, E. W.

2014-03-01

Newly discovered iron-based superconductor, Ca10(Pt4As8)(Fe2As2)5 (Tc = 34 K) is studied using scanning tunneling microscopy/spectroscopy (STM/S). Given the symmetry of the crystal structure, several surface terminations are expected with roughly same probability: 1) Ca or partial Ca layer on top Fe2As2; 2) Ca or partial Ca layer on top Pt4As8 layer; 3) A Fe2As2 layer, and; 4) A Pt4As8layer.Surprisingly,Fe2As2 related layers (1 & 3) are rarely observed (less than 1%). Instead, we observe Pt4As8 layers separated by unit-cell-high (~ 1 nm) steps accompanied with Ca or partial Ca layer on top Pt4As8 layer (1 - 2 Å step height). Scanning tunneling spectroscopy reveals different spectra for each surface, with superconducting coherence peaks seen only on Ca layers. We argue that intermediary layers are proximity-coupled to superconducting Fe2As2 layers. The results from Ca10(Pt4As8)(Fe2As2)5 are discussed with the properties observed in other iron-based superconductors. Funded by NSF

Comparative Study of Electronic Structure and Magnetic Properties of Osmate Double Perovskites: Ca2FeOsO6 versus Ca2Co(Ni)OsO6

NASA Astrophysics Data System (ADS)

Samanta, Kartik; Saha-Dasgupta, Tanusri

2018-04-01

Employing density functional theory, we study the trend in the electronic and magnetic properties of 3d-5d double perovskites, upon varying the 3d element for a fixed choice of 5d element, namely Ca2BOsO6 (B = Fe/Co/Ni). While all three compounds are reported to be ferrimagnets, the magnetic transition temperature of Ca2FeOsO6 is reported to be 2-2.4 times larger than that of Ca2CoOsO6 or Ca2NiOsO6. Our first-principles study provides microscopic insight into this trend. This trend is found to be caused by the downward shift in the position of d level energies of the B site element with respect to that of the Os t2g level upon moving across the 3d series from Fe to Co and Ni. This in turn changes the nominal valence of the Os ion from 5+ in Ca2FeOsO6 to 6+ in Ca2CoOsO6 and Ca2NiOsO6, resulting in differing superexchange paths between Ca2FeOsO6 and Ca2Co(Ni)OsO6, and additionally enabling the hybridization-mechanism-driven magnetism in Ca2FeOsO6. These together significantly enhance the magnetic transition temperature in Ca2FeOsO6 compared with that in Ca2Co(Ni)OsO6.

Sodium pyrophosphate enhances iron bioavailability from bouillon cubes fortified with ferric pyrophosphate.

PubMed

Cercamondi, Colin I; Duchateau, Guus S M J E; Harika, Rajwinder K; van den Berg, Robin; Murray, Peter; Koppenol, Wieneke P; Zeder, Christophe; Zimmermann, Michael B; Moretti, Diego

2016-08-01

Fe fortification of centrally manufactured and frequently consumed condiments such as bouillon cubes could help prevent Fe deficiency in developing countries. However, Fe compounds that do not cause sensory changes in the fortified product, such as ferric pyrophosphate (FePP), exhibit low absorption in humans. Tetra sodium pyrophosphate (NaPP) can form soluble complexes with Fe, which could increase Fe bioavailability. Therefore, the aim of this study was to investigate Fe bioavailability from bouillon cubes fortified with either FePP only, FePP+NaPP, ferrous sulphate (FeSO4) only, or FeSO4+NaPP. We first conducted in vitro studies using a protocol of simulated digestion to assess the dialysable and ionic Fe, and the cellular ferritin response in a Caco-2 cell model. Second, Fe absorption from bouillon prepared from intrinsically labelled cubes (2·5 mg stable Fe isotopes/cube) was assessed in twenty-four Fe-deficient women, by measuring Fe incorporation into erythrocytes 2 weeks after consumption. Fe bioavailability in humans increased by 46 % (P<0·005) when comparing bouillons fortified with FePP only (4·4 %) and bouillons fortified with FePP+NaPP (6·4 %). Fe absorption from bouillons fortified with FeSO4 only and with FeSO4+NaPP was 33·8 and 27·8 %, respectively (NS). The outcome from the human study is in agreement with the dialysable Fe from the in vitro experiments. Our findings suggest that the addition of NaPP could be a promising strategy to increase Fe absorption from FePP-fortified bouillon cubes, and if confirmed by further research, for other fortified foods with complex food matrices as well.

Fabrication and Luminescence Characterization of a Silica Nanomatrix Embedded with NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4 Nanoparticles

NASA Astrophysics Data System (ADS)

Thangaraju, Dheivasigamani; Santhana, Vedi; Matsuda, Satoshi; Hayakawa, Yasuhiro

2018-05-01

Hexagonal NaYF4:Yb:Er:Tm@NaGdF4 core-shell nanocrystals were synthesized using a seed mediated hot injection method, and monodispersed Fe3O4 (4 nm) nanoparticles were prepared from iron(II) actylacetonate by a precursor thermal decomposition method. Structural and morphology verified NaYF4:Yb:Er:Tm@NaGdF4 and Fe3O4 nanoparticles were utilized for the preparation of NaYF4:Yb:Er:Tm@NaGdF4/Fe3O4@SiO2 nanocomposite using a micro-emulsion method. Existence of Fe3O4 in NaYF4:Yb:Er:Tm@NaGdF4 in SiO2 nano-spheres were confirmed with transmission electron microscopy. Luminescence measurement revealed that NaYF4:Yb:Er:Tm@NaGdF4 exhibited strong emissions at green and red regions, in addition to a weak blue emission also observed under 980 nm excitation. Up-conversion emission of the nanoparticle-embedded silica nanocomposite showed that the up-conversion emission was not affected by Fe3O4 nanoparticles.

Color removal from dye-containing wastewater by magnesium chloride.

PubMed

Gao, Bao-Yu; Yue, Qin-Yan; Wang, Yan; Zhou, Wei-Zhi

2007-01-01

Color removal by MgCl(2) when treating synthetic waste containing pure dyes was studied. The color removal efficiency of MgCl(2)/Ca(OH)(2) was compared with that of Al(2)(SO(4))(3), polyaluminum chloride (PAC) and FeSO(4)/Ca(OH)(2). The mechanism of color removal by MgCl(2) was also investigated. The experimental results show that the color removal efficiency of MgCl(2) is related to the type of dye and depends on the pH of the waste and the dosage of the coagulants used. Treatment of waste containing reactive dye or dispersed dye with MgCl(2) yielded an optimum color removal ratio when the pH of the solution was equal to or above 12.0. For both the reactive and dispersed dye waste, MgCl(2)/Ca(OH)(2) was shown to be superior to MgCl(2)/NaOH, Al(2)(SO(4))(3), PAC and FeSO(4)/Ca(OH)(2) for color removal. A magnesium hydroxide precipitate formed at pH values greater than 12.0, which provided a large adsorptive surface area and a positive electrostatic surface charge, enabling it to remove the dyes through charge neutralization and an adsorptive coagulating mechanism. So, the MgCl(2)/Ca(OH)(2) system is a viable alternative to some of the more conventional forms of chemical treatment, especially for treating actual textile waste with high natural pH.

Dissolved organic matter degradation by sunlight coagulates organo-mineral colloids and produces low-molecular weight fraction of metals in boreal humic waters

NASA Astrophysics Data System (ADS)

Oleinikova, Olga V.; Drozdova, Olga Yu.; Lapitskiy, Sergey A.; Demin, Vladimir V.; Bychkov, Andrey Yu.; Pokrovsky, Oleg S.

2017-08-01

Photochemical degradation of dissolved organic matter (DOM) is recognized as the major driver of CO2 emission to the atmosphere from the inland waters of high latitudes. In contrast to numerous studies of photo-induced DOM transformation, the behavior of trace element (TE) during photodegradation of boreal DOM remains virtually unknown. Towards a better understanding of concentration, size fractionation and speciation change of DOM and TE in boreal waters subjected to solar radiation, we conducted on-site photo-degradation experiments in stream and bog water collected from a pristine zone of the Northern Karelia (Russian subarctic). The removal of Fe and Al occurred only in the bog water (90% and 50% respectively, over 5 days of reaction), whereas no detectable decrease of dissolved (<0.22 μm) Al and Fe concentration was observed in the boreal stream. A number of low-soluble TE linked to Fe-rich organo-mineral colloids followed the behavior of Fe during bog water exposure to sunlight: Al, P, Ti, V, Cr, As, Y, Zr, REEs, Hf, Th, Pb and U. The second group of elements (Li, B, Mg, Ca, Sr, Ba, Na, K, Rb, Si, Mn, Ni, Cu, Co, Cd, Sb) was indifferent to photodegradation of DOM and exhibited a non-systematic variation (±10-15% from the control) of <0.22 μm fraction in the course of sunlight exposure. The bog water insolation yielded a factor of 3 ± 1 increase of low molecular weight (LMW < 1 kDa) fraction of organic carbon, Al, Fe, U, Mg, Ca, Mn, Co, Ni, Sr, Cd and Ba after 200 h of sunlight exposure compared to the dark control. The LMW< 1 kDa fraction was preferentially enriched in Fe, Al, Ca, Mg and other divalent metals relative to Corg. The climate warming leading to water temperature rise in the boreal zone will intensify the Fe and Al hydroxide coagulation while increasing the production of LMW organic ligands and free metals and metal - organic complexes.

Sustainable treatment of different high-strength cheese whey wastewaters: an innovative approach for atmospheric CO2 mitigation and fertilizer production.

PubMed

Prazeres, Ana R; Rivas, Javier; Paulo, Úrsula; Ruas, Filipa; Carvalho, Fátima

2016-07-01

Raw cheese whey wastewater (CWW) has been treated by means of FeCl3 coagulation-flocculation, NaOH precipitation, and Ca(OH)2 precipitation. Three different types of CWW were considered: without cheese whey recovery (CWW0), 60 % cheese whey recovery (CWW60), and 80 % cheese whey recovery (CWW80). Cheese whey recovery significantly influenced the characteristics of the wastewater to be treated: organic matter, solids, turbidity, conductivity, sodium, chloride, calcium, nitrogen, potassium, and phosphorus. Initial organic load was reduced to values in the interval of 60-70 %. Application of FeCl3, NaOH, or Ca(OH)2 involved additional chemical oxygen demand (COD) depletions regardless of the CWW used. Under optimum conditions, the combination of 80 % cheese whey recovery and lime application led to 90 % reduction in COD. Turbidity (99.8%), total suspended solids (TSS) (98-99 %), oils and fats (82-96 %), phosphorus (98-99 %), potassium (96-97 %), and total coliforms (100 %) were also reduced. Sludge generated in the latter process showed excellent settling properties. This solid after filtration and natural evaporation can be used as fertilizer with limitations due to its saline nature. In an innovative, low-cost, and environmentally friendly technology, supernatant coming from the Ca(OH)2 addition was naturally neutralized in 4-6 days by atmospheric CO2 absorption without reagent addition. Consequently, a final aerobic biodegradation step can be applied for effluent polishing. This technology also allows for some atmospheric CO2 mitigation. Time requirement for the natural carbonation depends on the effluent characteristics. A precipitate rich in organic matter and nutrients and depletions of solids, sodium, phosphorus, magnesium, Kjeldahl, and ammoniacal nitrogen were also achieved during the natural carbonation.

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.

Major and trace elements in igneous rocks from Apollo 15.

NASA Technical Reports Server (NTRS)

Helmke, P. A.; Blanchard, D. P.; Haskin, L. A.; Telander, K.; Weiss, C.; Jacobs, J. W.

1973-01-01

The concentrations of major and trace elements have been determined in igneous rocks from Apollo 15. All materials analyzed have typical depletions of Eu except for minerals separated from sample 15085. Four samples have concentrations of trace elements that are similar to those of KREEP. The samples of mare basalt from Apollo 15 have higher concentrations of FeO, MgO, Mn, and Cr and lower concentrations of CaO, Na2O, K2O, and rare-earth elements (REE) as compared to the samples of mare basalt from Apollos 11, 12, and 14. The samples can be divided into two groups on the basis of their normative compositions. One group is quartz normative and has low concentrations of FeO while the other is olivine normative and has high concentrations of FeO. The trace element data indicate that the samples of olivine normative basalt could be from different portions of a single lava flow.

Chemical Compositions of Kinematically Selected Outer Halo Stars

NASA Astrophysics Data System (ADS)

Zhang, Lan; Ishigaki, Miho; Aoki, Wako; Zhao, Gang; Chiba, Masashi

2009-12-01

Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including α-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results. We find a decreasing trend of [α/Fe] with increasing [Fe/H] for the range of -3.5< [Fe/H] <-1, as found by Stephens & Boesgaard. [Zn/Fe] values of most objects in our sample are slightly lower than the bulk of halo stars previously studied. These results are discussed as possible chemical properties of the outer halo in the Galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Properties of the Ca2+ influx reveal the duality of events underlying the activation by vanadate and fluoride of the Gárdos effect in human red blood cells.

PubMed

Varecka, L; Peterajová, E; Písová, E

1998-08-14

The properties of the 45Ca2+ influx by human red blood cells (RBC) induced by NaVO3 or NaF were compared. The NaVO3-induced 45Ca2+ influx was slower and less extensive than that induced by NaF. Both processes were saturable with Ca2+. Substitution of Na+ by K+ inhibited the 45Ca2+ influx induced by NaVO3 but stimulated that by NaF. The NaVO3-induced Ca2+ influx was sensitive to nifedipine (IC50 = 50 mol/l), Cu2+ (IC50=9 mol/l), DTNB (5,5'-dithiobis-(dinitrobenzoic acid)) (IC50 = 12 mol/l) (maximal inhibition 16%, 18%, and 28%, respectively, if NaF was used as inducer). On the other hand, tetrodotoxin (TTX) and cyclosporin A inhibited only the NaF-induced 45Ca2+ influx (IC50 = 21 mol/l and 28 mol/l, respectively). Pig RBC, known not to display the NaVO3-induced Ca2+ influx, exhibited Ca2+ influx induced by NaF. The results show that NaVO3 activates the Ca2+ influx via a pathway homologous to the L-type Ca2+ channel while the NaF-induced Ca2+ influx is mediated via the TTX-sensitive Na+ channel in the presence of NaF with possible participation of calcineurin or cyclophilin. Thus, the Gardos effect induced by NaVO3 and NaF represents two phenomena activated by different mechanisms present in the cryptic state in the RBC membrane.

Co-intercalation of Mg(2+) and Na(+) in Na(0.69)Fe2(CN)6 as a High-Voltage Cathode for Magnesium Batteries.

PubMed

Kim, Dong-Min; Kim, Youngjin; Arumugam, Durairaj; Woo, Sang Won; Jo, Yong Nam; Park, Min-Sik; Kim, Young-Jun; Choi, Nam-Soon; Lee, Kyu Tae

2016-04-06

Thanks to the advantages of low cost and good safety, magnesium metal batteries get the limelight as substituent for lithium ion batteries. However, the energy density of state-of-the-art magnesium batteries is not high enough because of their low operating potential; thus, it is necessary to improve the energy density by developing new high-voltage cathode materials. In this study, nanosized Berlin green Fe2(CN)6 and Prussian blue Na(0.69)Fe2(CN)6 are compared as high-voltage cathode materials for magnesium batteries. Interestingly, while Mg(2+) ions cannot be intercalated in Fe2(CN)6, Na(0.69)Fe2(CN)6 shows reversible intercalation and deintercalation of Mg(2+) ions, although they have the same crystal structure except for the presence of Na(+) ions. This phenomenon is attributed to the fact that Mg(2+) ions are more stable in Na(+)-containing Na(0.69)Fe2(CN)6 than in Na(+)-free Fe2(CN)6, indicating Na(+) ions in Na(0.69)Fe2(CN)6 plays a crucial role in stabilizing Mg(2+) ions. Na(0.69)Fe2(CN)6 delivers reversible capacity of approximately 70 mA h g(-1) at 3.0 V vs Mg/Mg(2+) and shows stable cycle performance over 35 cycles. Therefore, Prussian blue analogues are promising structures for high-voltage cathode materials in Mg batteries. Furthermore, this co-intercalation effect suggests new avenues for the development of cathode materials in hybrid magnesium batteries that use both Mg(2+) and Na(+) ions as charge carriers.

Creation of a 3Mn/1Fe cluster in the oxygen-evolving complex of photosystem II and investigation of its functional activity.

PubMed

Semin, B К; Davletshina, L N; Seibert, M; Rubin, A B

2018-01-01

Extraction of Mn cations from the oxygen-evolving complex (OEC) of Ca-depleted PSII membranes (PSII[-Ca,4Mn]) by reductants like hydroquinone (H 2 Q) occurs with lower efficiency at acidic pH (2Mn/reaction center [RC] are extracted at pH5.7) than at neutral pH (3Mn/RC are extracted at pH6.5) [Semin et al. Photosynth. Res. 125 (2015) 95]. Fe(II) also extracts Mn cations from PSII(-Ca,4Mn), but only 2Mn/RC at pH6.5, forming a heteronuclear 2Mn/2Fe cluster [Semin and Seibert, J. Bioenerg. Biomembr. 48 (2016) 227]. Here we investigated the efficiency of Mn extraction by Fe(II) at acidic pH and found that Fe(II) cations can extract only 1Mn/RC from PSII(-Ca,4Mn) membranes at pH 5.7, forming a 3Mn/1Fe cluster. Also we found that the presence of Fe cations in a heteronuclear cluster (2Mn/2Fe) increases the resistance of the remaining Mn cations to H 2 Q action, since H 2 Q can extract Mn cations from homonuclear Mn clusters of PSII(-Ca,4Mn) and PSII(-Ca,2Mn) membranes but not from the heteronuclear cluster in PSII(-Ca,2Mn,2Fe) membranes. H 2 Q also cannot extract Mn from PSII membranes obtained by incubation of PSII(-Ca,4Mn) membranes with Fe(II) cations at pH5.7, which suggests the formation of a heteronuclear 3Mn/1Fe cluster in the OEC. Functional activity of PSII with a 3Mn/1Fe cluster was investigated. PSII preparations with a 3Mn/1Fe cluster in the OEC are able to photoreduce the exogenous electron acceptor 2,6-dichlorophenolindophenol, possibly due to incomplete oxidation of water molecules as is the case with PSII(-Ca,2Mn,2Fe) samples. However, in the contrast to PSII(-Ca,2Mn,2Fe) samples PSII(-Ca,3Mn,1Fe) membranes can evolve O 2 at a low rate in the presence of exogenous Ca 2+ (at about 27% of the rate of O 2 evolution in native PSII membranes). The explanation for this phenomenon (either water splitting and production of molecular O 2 by the 3Mn/1Fe cluster or apparent O 2 evolution due to minor contamination of PSII(3Mn,1Fe) samples with PSII(-Ca,4Mn) membranes) is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Iron bioavailability in 8-24-month-old Thai children from a micronutrient-fortified quick-cooking rice containing ferric ammonium citrate or a mixture of ferrous sulphate and ferric sodium ethylenediaminetetraacetic acid.

PubMed

Chavasit, Visith; Porasuphatana, Suparat; Suthutvoravut, Umaporn; Zeder, Christroph; Hurrell, Richard

2015-12-01

A quick-cooking rice, produced from broken rice, is a convenient ingredient for complementary foods in Thailand. The rice is fortified with micronutrients including iron during the processing procedure, which can cause unacceptable sensory changes. A quick-cooking rice fortified with ferric ammonium citrate (FAC) or a mixture of ferrous sulphate (FeSO4 ) and ferric sodium ethylenediaminetetraacetic acid (NaFeEDTA), with a 2:1 molar ratio of iron from FeSO4  : iron from NaFeEDTA (FeSO4  + NaFeEDTA), gave a product that was organoleptically acceptable. The study compared iron absorption by infants and young children fed with micronutrient-fortified quick-cooking rice containing the test iron compounds or FeSO4 . Micronutrient-fortified quick-cooking rice prepared as a traditional Thai dessert was fed to two groups of 15 8-24-month healthy Thai children. The iron fortificants were isotopically labelled with (57) Fe for the reference FeSO4 or (58) Fe for the tested fortificants, and iron absorption was quantified based on erythrocyte incorporation of the iron isotopes 14 days after feeding. The relative bioavailability of FAC and of the FeSO4  + NaFeEDTA was obtained by comparing their iron absorption with that of FeSO4 . Mean fractional iron absorption was 5.8% [±standard error (SE) 1.9] from FAC and 10.3% (±SE 1.9) from FeSO4  + NaFeEDTA. The relative bioavailability of FAC was 83% (P = 0.02). The relative bioavailability of FeSO4  + NaFeEDTA was 145% (P = 0.001). Iron absorption from the rice containing FAC or FeSO4  + NaFeEDTA was sufficiently high to be used in its formulation, although iron absorption from FeSO4  + NaFeEDTA was significantly higher (P < 0.00001). © 2015 John Wiley & Sons Ltd.

Extremely arsenic-rich, pH-neutral waters from the Giant Mine, Canada

USGS Publications Warehouse

Nordstrom, D. Kirk

2013-01-01

Roasting arsenopyrite-bearing gold ore for more than fifty years has resulted in nearly 300,000 tons of arsenic trioxide waste at the Giant mine near Yellowknife, NWT, Canada. Most of this has been stored in underground chambers sealed with concrete bulkheads. Seepages from underground drillholes and fractures contain up to 4,000 mg As L-1. Approximately 70% of the total is As(III). The dominant dissolved constituents are As, Ca, Mg, Na and SO4 with low Fe.

Structure of Fe(III) precipitates generated by Fe(0) electrocoagulation in the presence of groundwater ions

NASA Astrophysics Data System (ADS)

van Genuchten, C. M.; Pena, J.; Addy, S. E.; Gadgil, A. J.

2012-12-01

Electrocoagulation (EC) using Fe(0) electrodes is an inexpensive and efficient technology capable of removing a variety of contaminants from water supplies. Because of its ease of use and modest electricity and Fe(0) requirements, EC has potential as an arsenic-removal technology for rural South Asia, where millions drink groundwater contaminated by arsenic. In EC, a small external voltage applied to a sacrificial Fe(0) anode in contact with an electrolyte (e.g. pumped groundwater containing arsenic) promotes the oxidative dissolution of Fe ions, which polymerize and create reactive hydrous ferric oxides (HFO) in-situ with a high affinity for binding contaminants. The chemical composition of the electrolyte influences EC performance. For example, major inorganic ions present in groundwater (e.g. Ca, Mg, P, As(V), Si) alter the pathway by which FeO6 oligomers polymerize to form crystalline Fe (oxyhydr)oxide minerals. Because the precipitate structure largely determines properties that govern the efficiency of EC systems (e.g. precipitate reactivity and colloidal stability), it is essential to understand the individual and interdependent structural effects of common groundwater ions. In this work, we integrate Fe K-edge EXAFS spectroscopy with the Pair Distribution Function (PDF) technique to create a detailed description of EC precipitate structure as a function of electrolyte chemistry. EC precipitate samples were generated in a range of individual and combined concentrations of Ca, Mg, P, As(V), and Si, encompassing most of the typical levels found in natural groundwater. Combining complementary EXAFS and PDF techniques with batch uptake experiments and general chemical reasoning, we obtain structural representations of EC precipitates that are inaccessible with any single characterization technique. Our results indicate that the presence of As(V), P, and Si oxyanions promote the formation of nanoscale material bearing similar, but not identical, intermediate-ranged atomic pair correlations as 2-line ferrihydrite (2LFH), rather than lepidocrocite (Lp) which is generated in an NaCl electrolyte. However, when Ca or Mg is added to oxyanion electrolytes, Fe-Fe polymerization and particle size both tend to increase and a Lp-like material with characteristic Fe-O and Fe-Fe pair correlations is once again favored. The presence of either Ca or Mg also enhances the removal P, As(V), and to a lesser extent, Si per mass of Fe. The analysis from EXAFS and PDF spectra provide new insights into the polyhedral connectivity of nanoscale oxyanion-bearing HFO formed under a wide range of chemical conditions, improving predictions of EC performance in the field and allowing for knowledge-based improvements in the design of future EC systems. Our PDF data also show that the most disordered EC precipitate samples (formed at high oxyanion/Fe ratios) all share a similar "backbone" of 3-4 peaks beyond the first 4 Å, regardless of the oxyanion present during synthesis. Using 2LFH as a reference, we index all atomic pair correlations throughout the coherently scattering structure of our disordered samples.

Crystalline and Electronic Structures and Magnetic and Electrical Properties of La-Doped Ca2Fe2O5 Compounds

NASA Astrophysics Data System (ADS)

Phan, T. L.; Tho, P. T.; Tran, N.; Kim, D. H.; Lee, B. W.; Yang, D. S.; Thiet, D. V.; Cho, S. L.

2018-01-01

Brownmillerite Ca2Fe2O5 has been observed to exhibit many outstanding properties that are applicable to ecotechnology. However, very little work on doped Ca2Fe2O5 compounds has been carried out to widen their application scope. We present herein a detailed study of the crystalline/geometric and electronic structures and magnetic and electrical properties of Ca2- x La x Fe2O5 ( x = 0 to 1) prepared by conventional solid-state reaction. X-ray diffraction patterns indicated that the compounds with x = 0 to 0.05 exhibited brownmillerite-type single phase. La doping with higher content ( x ≥ 0.1) stimulated additive formation of Grenier- (LaCa2Fe3O8) and perovskite-type (LaFeO3) phases. Extended x-ray absorption fine structure spectroscopy at the Fe K-edge and electron spin resonance spectroscopy revealed presence of Fe3+ in the parent Ca2Fe2O5 ( x = 0) and both Fe3+ and Fe4+ in the doped compounds ( x ≥ 0.05). The Fe4+ content tended to increase with increasing x. This stimulates ferromagnetic exchange interactions between Fe3+ and Fe4+ ions and directly influences the magnetic properties of Ca2- x La x Fe2O5. Electrical resistivity ( ρ) measurements in the temperature range of T = 20 K to 400 K revealed that all the compounds exhibit insulator behavior; the ρ( T) data for x ≥ 0.1 could be described based on the adiabatic small polaron hopping model.

Soil-plant-animal continuum in relation to macro and micro mineral status of dairy cattle in subtropical hill agro ecosystem.

PubMed

Kumaresan, A; Bujarbaruah, K M; Pathak, K A; Brajendra; Ramesh, T

2010-04-01

The purpose of the present study was to study the soil-plant-animal continuum in subtropical hilly areas. Soil (n = 96), fodder (n = 96), and blood serum samples from dairy cattle (n = 120) were collected from eight districts of Mizoram, a hilly state in India. The samples were digested using diacid mixture (HNO(3):HClO(4); 10:4) and analyzed for macro (Ca, P, Mg, Na, and K) and micro (Cu, Co, Mn, Fe, and Zn) mineral concentrations. The macro and micro mineral concentrations varied among the different districts. The correlation values between fodder and cattle were significant for all the minerals studied except for P and K. The correlation value between fodder and cattle was highly significant (P < 0.01) for Ca (0.878), Mg (0.88), Cu (0.885), and Zn (0.928). However, such correlations were not observed between the mineral levels in cattle and mineral levels in soil except for Ca (0.782). Equations developed in the present study for prediction of Ca (R(2) = 0.797), Mg (R(2) = 0.777), Zn (R(2) = 0.937), Fe (R(2) = 0.861), and Cu (R(2) = 0.794) had significant R(2) values. Further, it is inferred that dairy cattle reared under smallholder production system were deficient in most of the minerals and supplementation of required minerals is essential for optimum production.

Mineral composition of lamb carcasses from the United States and New Zealand.

PubMed

Lin, K C; Cross, H R; Johnson, H K; Breidenstein, B C; Randecker, V; Field, R A

1988-01-01

The mineral composition-iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), fluoride (F), and phosphorus (P) (New Zealand lamb only)-of lean tissue from lamb retail cuts was studied. Twenty-four US lamb carcasses of different ages (5 to 11 months), geographical regions (Texas, Colorado and Montana) and USDA quality grades (Prime and Choice) and 27 New Zealand lamb carcasses from three weight groups (11 to 12·5 kg, 13 to 14·5 kg, and 16·5 to 18 kg), age rangining from 7 to 8 months, were selected for use in this study. Mineral concentrations were influenced more by retail cut and age than by quality grade or weigth group. Foreshank and shoulder cuts from both the US and New Zealand group consistently had the highest (P < 0·05) Zn content among the cuts. The K content of the muscle in US lambs increased as age increased, while the level of Ca and Zn in New Zealand lambs decreased as carcass weight increased. Except for Ca, the mineral concentrations of the lean tissue from US lambs were higher than the New Zealand lambs, although the differences were not always significant. US lambs had approximately 20%, 30% and 37% more Fe, Zn and Mg, respectively, but 27% less Ca than lean tissue from the New Zealand lambs. Copyright © 1989. Published by Elsevier Ltd.

Formation and composition of the moon

NASA Technical Reports Server (NTRS)

Anderson, D. L.

1977-01-01

Many of the properties of the Moon, including the enrichment in Ca, Al, Ti, U, Th, Ba, Sr, and the REE and the depletion in Fe, Rb, K, Na, and other volatiles can be understood if the Moon represents a high-temperature condensate from the solar nebula. Thermodynamic calculations show that Ca-, Al-, and Ti-rich compounds condense first in a cooling nebula. The initial high temperature mineralogy is gehlenite, spinel, perovskite, Ca-Al-rich pyroxenes, and anorthite. Inclusions in carbonaceous chondrites such as the Allende meteorite are composed primarily of these minerals and, in addition, are highly enriched in refractories such as REE relative to carbonaceous chondrites. These inclusions can yield basalt and anorthosite in the proportions required to eliminate the europium anomaly, leaving a residual spinel-melilite interior. A deep interior high in Ca-Al does not imply an unacceptable mean density or moment of inertia for the Moon. The inferred high-U content of the lunar interior, both from the Allende analog and the high heat flow, indicates a high-temperature interior. The model is consistent with extensive early melting, with shallow melting at 3 AE, and with presently high deep internal temperatures. It is predicted that the outer 250 km is rich in plagioclase and FeO. The low iron content of the interior in this model raises the interior temperatures estimated from electrical conductivity by some 800 C.

Silicate minerals for CO2 scavenging from biogas in Autogenerative High Pressure Digestion.

PubMed

Lindeboom, Ralph E F; Ferrer, Ivet; Weijma, Jan; van Lier, Jules B

2013-07-01

Autogenerative High Pressure Digestion (AHPD) is a novel concept that integrates gas upgrading with anaerobic digestion by selective dissolution of CO2 at elevated biogas pressure. However, accumulation of CO2 and fatty acids after anaerobic digestion of glucose resulted in pH 3-5, which is incompatible with the commonly applied high-rate methanogenic processes. Therefore, we studied the use of wollastonite, olivine and anorthosite, with measured composition of CaSi1.05O3.4, Mg2Fe0.2Ni0.01Si1.2O5.3 and Na0.7Ca1K0.1Mg0.1Fe0.15Al3.1Si4O24, respectively, to scavenge CO2 during batch AHPD of glucose. Depending on the glucose to mineral ratio the pH increased to 6.0-7.5. Experiments with wollastonite showed that Ca(2+)-leaching was caused by volatile fatty acid (VFA) production during glucose digestion. At 1, 3 and 9 bar, the CH4 content reached 74%, 86% and 88%, respectively, indicating CO2 scavenging. Fixation of produced CO2 by CaCO3 precipitation in the sludge was confirmed by Fourier Transferred-InfraRed, Combined Field emission Scanning Electron Microscopy-Energy-dispersive X-ray spectroscopy and Thermogravimetric Analysis-Mass Spectroscopy. Copyright © 2013 Elsevier Ltd. All rights reserved.

Synthesis and chemical characterization of the novel agronomically relevant pentadentate chelate 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA).

PubMed

López-Rayo, Sandra; Hernández, Diana; Lucena, Juan J; Escudero, Rosa; Gómez-Gallego, Mar; Sierra, Miguel A

2010-07-14

Iron chelates analogous to o,o-EDDHA/Fe(3+) are the fertilizers chosen to treat iron chlorosis in plants growing on calcareous soil. The isomer o,p-EDDHA/Fe(3+) presents less stability but faster assimilation by the plant than o,o-EDDHA/Fe(3+), because only five coordinating groups are able to complex Fe(3+). The new chelating agent 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA) has been synthesized to obtain an iron fertilizer with intermediate stability between o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) and with fast assimilation. Its synthesis has been done starting from phenol, N-acetylethylendiamine, glyoxylic acid, and NaOH in a three-step sequence. The purity of the DCHA chelating agent, its protonation, and Ca(2+), Mg(2+), Fe(3+), and Cu(2+) stability constants, together with its ability to maintain iron in solution in different agronomic conditions, have been determined. The results indicate that the chelate DCHA/Fe(3+) has intermediate stability between those of o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) complexes and that it is capable of maintaining the Fe(3+) in agronomic conditions. This new chelating agent may be effective in correcting iron chlorosis in plants.

Synthesis and characterization of intercalated few-layer graphenes

NASA Astrophysics Data System (ADS)

Sato, Shogo; Ichikawa, Hiroaki; Iwata, Nobuyuki; Yamamoto, Hiroshi

2014-02-01

Toward achieving room-temperature superconductivity, FeCl3-intercalated few-layer graphenes (FeCl3-FLGs) and Ca-intercalated few-layer graphenes (Ca-FLGs) were synthesized. FeCl3-FLGs were synthesized by the two-zone method and Ca-FLGs were synthesized using Ca-Li alloy. The Raman spectra of the FeCl3-FLGs showed a lower-intensity peak at 1607 cm-1 than that of the corresponding bare G. The peak at 1607 cm-1 suggested that the sample was stage 4-5 FeCl3-FLGs. The room-temperature electrical resistivity of FeCl3-FLGs was 2.65 × 10-5 Ω·m, which linearly decreased with decreasing temperature with a marked change occurring at approximately 200 K. From a XRD pattern of Ca-FLGs, we concluded that Ca is intercalated in FLGs. The room-temperature resistivity of Ca-FLGs was 3.45 × 10-5 Ω·m, which increased with decreasing temperature.

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe(III) in the presence of citric acid

PubMed Central

ZHANG, Xiang; GU, Xiaogang; LU, Shuguang; MIAO, Zhouwei; XU, Minhui; FU, Xiaori; DANISH, Muhammad; Brusseau, Mark L.; QIU, Zhaofu; SUI, Qian

2017-01-01

Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting H2O2 generation. The generation of HO• and O2−• in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly o direct oxidation by HO•, while O2−• strengthened the generation of HO• by promoting Fe(III) transformation in the CP/Fe(III)/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl−, HCO3−, and humic acid (HA) inhibited TCE degradation to different extents for the CP/Fe(III)/CA system. Analysis of Cl− production suggested that TCE degradation in the CP/Fe(III)/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe(III)-activated calcium peroxide for treating TCE contaminated groundwater. PMID:28959499

The effects of low sodium solutions on intracellular calcium concentration and tension in ferret ventricular muscle.

PubMed

Allen, D G; Eisner, D A; Lab, M J; Orchard, C H

1983-12-01

Papillary muscles from the right ventricles of ferrets were micro-injected with the photoprotein aequorin. Both tension and the light emitted by the aequorin, which is a measure of the free intracellular Ca concentration [( Ca2+]i), were monitored. Exposure of the papillary muscle to a solution in which all the Na had been replaced by K (0 Na(K) solution) resulted in an increase in tension which subsequently slowly decreased. This contracture was associated with a large increase in [Ca2+]i followed by a decrease to a steady-state-level which was often significantly greater than that in Na-containing solutions. If choline, Li or Tris was used instead of K as a substitute for Na, both the contracture and the associated increase of [Ca2+]i were reduced. The effects of depolarization alone (by raising external K at constant Na concentration) were compared with those of Na removal alone (at constant external K concentration). Na removal contributes more than depolarization to the effects of a Na-free, K-containing solution on the contracture and rise of [Ca2+]i. Increasing intracellular Na concentration [( Na+]i), by exposure to strophanthidin (10 mumol/l), increased the magnitude of both the contracture and [Ca2+]i in 0 Na(K) solutions. Conversely, decreasing [Na+]i by exposure to a solution containing a decreased extracellular Na concentration [( Na+]o), decreased the contracture and [Ca2+]i. When contractures were produced by solutions with various [Na+]o, the size of the resulting contracture and [Ca2+]i were inversely related to [Na+]o. No contracture was seen unless [Na+]o was reduced to below 70 mmol/l. A decrease in the extracellular Ca concentration [( Ca2+]o) from 2 to 0.5 mmol/l or an increase to 8 mmol/l produced, respectively, large decreases and increases of the twitch and accompanying Ca transient. However, if [Ca2+]o was changed at the same time as Na was replaced by K there was little effect on either the contracture or the rise of [Ca2+]i. If [Ca2+]o was changed before replacing Na by K then increasing [Ca2+]o from 2 to 8 mmol/l decreased, and decreasing [Ca2+]o from 2 to 0.5 mmol/l increased, the rise of [Ca2+]i produced by replacing Na by K. The difference between this result and that obtained when [Ca2+]o was changed at the same time as Na was removed may be due to changes of [Na+]i produced by prolonged exposure to an altered [Ca2+]o.(ABSTRACT TRUNCATED AT 400 WORDS)

Seedless synthesis and efficient recyclable catalytic activity of Ag@Fe nanocomposites towards methyl orange

NASA Astrophysics Data System (ADS)

Alzahrani, Salma Ahmed; Malik, Maqsood Ahmad; Al-Thabaiti, Shaeel Ahmed; Khan, Zaheer

2018-03-01

This work demonstrates a competitive reduction method of synthesis of nanomaterials. In this method along cetyltrimethylammonium bromide (CTAB), the reduction of Ag+ and Fe3+ ions is achieved by ascorbic acid-to-bimetallic Ag@Fe yellow-colored nanomaterials. The shape of UV-visible spectra and wavelengths absorbed of Ag@Fe can be tuned from ca. 290-600 nm by controlling [CTAB] and [Ag+]. The apparent first-order rate constants were calculated within the approximation of 6.1 × 10-3 s-1. The as-prepared Ag@Fe NPs have been found to be very important catalyst in terms of depredate methyl orange in vicinity of sodium borohydride (NaBH4), which exhibits excellent efficiency and re-usability in the prototypical reaction. The cmc of cationic surfactant CTAB has been determined by conductivity method under different experimental conditions. In the presence of CTAB, Ag+ and Fe3+ ions reduce to Ag@Fe core/shell nanoparticles, comprehend a change in wavelength and intensity of SRP band. The apparent first-order rate constant, activation energy, and turnover frequency for the methyl orange reduction catalyzed by Ag@Fe NPs were found to be 1.6 × 10-3 s-1, 58.2 kJ mol-1, and 1.1 × 10-3 s-1, respectively.

Efficiency of several leaching reagents on removal of Cu, Pb, Cd, and Zn from highly contaminated paddy soil.

PubMed

Gao, Ruili; Zhu, Pengfei; Guo, Guangguang; Hu, Hongqing; Zhu, Jun; Fu, Qingling

2016-11-01

The efficiency of five different single leaching reagents (tartaric acid (TA), citric acid (CA), CaCl 2 , FeCl 3 , EDTA) and two different composite leaching reagents (CA + FeCl 3 , CA + EDTA) on removing Cu, Pb, Zn, and Cd from contaminated paddy soil in Hunan Province (in China) was studied. The results indicated that the efficiencies of CA, FeCl 3 , and EDTA on extracting Cu, Pb, Cd, and Zn from soil were greater than that of TA and CaCl 2 , and their extraction efficiencies were EDTA ≥ FeCl 3 > CA. The efficiencies of CA + FeCl 3 on extracting Cu, Pb, Cd, and Zn were higher than that of single CA or FeCl 3 . The 25 mmol L -1 CA + 20 mmol L -1 FeCl 3 was a promising composite leaching reagent for paddy soil, and it could remove Cu (57.6 %), Pb (59.3 %), Cd (84.8 %), and Zn (28.0 %), respectively. With the same amount of leaching reagent, the efficiency of continuous leaching by several times was higher than that by once. In addition, the easily reducible and oxidizable fractions of heavy metals showed significant decrease during the process of leaching.

Low magnesium diet alters distribution of macroelements and trace elements in tissues and organs of female rats.

PubMed

Zheltova, Anastasia A; Kharitonova, Maria V; Iezhitsa, Igor N; Serebryansky, Eugeny P; Evsyukov, Oleg Y; Spasov, Alexander A; Skalny, Anatoly V

2017-01-01

The aim of the present study was to assess whether dietary magnesium deficiency can alter distribution of macroelements and trace elements in different organs and tissues. Experiments were carried out on 12 adult female Wistar rats, which were fed either a diet with low Mg content (≤20mgkg -1 of diet) (LMgD) or a diet with daily recommended Mg content (≈500mgkg -1 ) as control group (CG) for 70 days. On the 70th day of the experiment heart, aorta, femoral skeletal muscle, forebrain, cerebellum, pituitary gland, thyroid gland, ovaries, uterus, liver, kidneys, and spleen were taken for analysis of mineral content. Concentrations of Fe and Ca were measured by inductively coupled plasma-atomic emission spectrometry, and levels of Na, K, Mg, Co, Cu, Zn, Ni, Se, I were determined by inductively coupled plasma mass spectrometry. On the 70th day, LMgD led to significant reduction of Mg level in red blood cells, plasma, aorta, uterus and thyroid gland compared to CG as well as resulted in significant decrease of Mg/Ca ratio in kidneys, spleen and ovaries. Contrary to this, an increase of Mg/Ca ratio was found in cerebellum of LMgD group. Significant decrease of K concentration was shown in aorta of LMgD animals compared to CG whereas myocardial K concentration was increased in LMgD group. Na level was two-fold higher in skeletal muscles of rats that received LMgD in comparison to CG (p=0.006). Increased concentrations of Fe in ovaries and uterus were found in LMgD. Mg restriction did not affect Zn concentration in any of tasted tissues. Se level was higher in spleen and lower in uterus of LMgD animals compared to CG. MgD was accompanied by increased level of Co in skeletal muscles and decreased its level in kidneys and uterus. LMgD feeding was associated with decreased concentrations of Ni in heart, thyroid gland, spleen, uterus and Co in heart, aorta, liver, kidneys, spleen and ovaries. The changes of Mg, K, Co content were accompanied by dramatic (10-fold) decrease of I concentration in aorta of LMgD animals. LMgD causes decrease of I content in ovaries and increase of I level in uterus vs CG. Thus, distribution of macroelements (Ca, Na, K) was weakly affected by Mg restriction that led to the most evident alterations of Co and Ni tissue levels. Moreover, mineral balance of uterus seems to be the most susceptible to low Mg intake. Hypomagnesaemia resulted in significant changes of 5 studied trace elements (Fe, Se, Cu, Ni and Co). Copyright © 2016 Elsevier GmbH. All rights reserved.

Phase equilibria in the NaF-CdO-NaPO{sub 3} system at 873 K and crystal structure and physico-chemical characterizations of the new Na{sub 2}CdPO{sub 4}F fluorophosphate

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

Aboussatar, Mohamed; Laboratoire de Physico-Chimie de l’État Solide, Faculté des Sciences de Sfax, Université de Sfax, BP 1171, 3000 Sfax; Mbarek, Aïcha

Isothermal sections of the diagram representing phase relationships in the NaF-CdO-NaPO{sub 3} system have been investigated by solid state reactions and powder X-ray diffraction. This phase diagram investigation confirms the polymorphism of the NaCdPO{sub 4} side component and the structure of the ß high temperature polymorph (orthorhombic, space group Pnma and unit cell parameters a=9.3118(2), b=7.0459(1), c=5.1849(1) Å has been refined. A new fluorophosphate, Na{sub 2}CdPO{sub 4}F, has been discovered and its crystal structure determined and refined from powder X-ray diffraction data. It exhibits a new 3D structure with orthorhombic symmetry, space group Pnma and unit cell parameters a=5.3731(1), b=6.8530(1),more » c=12.2691(2) Å. The structure is closely related to those of the high temperature polymorph of the nacaphite Na{sub 2}CaPO{sub 4}F and the fluorosilicate Ca{sub 2}NaSiO{sub 4}F but differs essentially in the cationic repartition since the structure is fully ordered with one Na site (8d) and one Cd site (4c). Relationships with other Na{sub 2}M{sup II}PO{sub 4}F (M{sup II}=Mg, Ca, Mn, Fe, Co, Ni) have been examined and the crystal-chemical and topographical analysis of these fluorophosphates is briefly reviewed. IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F have been investigated. - Graphical abstract: The structure of the compound Na{sub 2}CdPO{sub 4}F, discovered during the study of the phase relationships in the NaF-CdO-NaPO{sub 3} system, has been determined and compared with other Na{sub 2}M{sup II}PO{sub 4}F fluorophosphates. - Highlights: • XRD analysis of the isothermal section of the NaF-CdO-NaPO{sub 3} system at 923 K. • Rietveld refinement of the high temperature polymorph β-NaCdPO{sub 4}. • Crystal structure of the new Na{sub 2}CdPO{sub 4}F fluorophosphate determined from powder XRD. • Crystal structure - composition relationships of Na{sub 2}M{sup II}PO{sub 4}F compounds are reviewed. • IR, Raman, optical and {sup 19}F, {sup 23}Na, {sup 31}P MAS NMR characterizations of Na{sub 2}CdPO{sub 4}F.« less

Effect of Initial FeO Content and CaO:SiO2 Ratio on the Reduction Smelting Kinetics of the CaO-SiO2-MgOsatd.-FeO Slag System

NASA Astrophysics Data System (ADS)

Kim, Jong Bae; Sohn, Il

2018-02-01

The effect of the initial FeO content and CaO:SiO2 ratio (CaO mass pct/SiO2 mass pct) on the reduction smelting of FeO with carbon flake addition is investigated in the CaO-MgOsatd.-SiO2-FeO slag system at 1823 K (1550 °C). Carbon rapidly reacted with FeO in the molten slag, causing both foaming and compositional changes in the slag. As FeO is reduced, the MgO saturation is modified, and solid precipitants, including MgO and other complex oxides, were observed, which significantly affected the slag properties, including the viscosity and foaming behavior. The solid-phase fraction and viscosity were estimated from changes in the measured FeO content over time using the thermochemical software FactSage. The iron recovery, which is distinguished from the amount of reduced Fe droplets, showed opposite behavior to the measured maximum foaming height and modified foaming index. According to the FeO mass transfer coefficient considering slag foaming at various initial FeO contents and CaO:SiO2 ratios, the reduction rate was optimal at higher initial FeO contents and a CaO:SiO2 ratio of 2.0, which did not correspond to the optimal iron recovery at an initial FeO content of 44 mass pct and above and a CaO:SiO2 ratio of 1.2. The results showed that slag foaming may increase the reduction kinetics, but the slag composition needs to be optimized for greater iron recovery.

Earthworm Activity and the Potential for Enhanced Leaching of Inorganic Elements in Soils

NASA Astrophysics Data System (ADS)

Gruau, G.; Ablain, F.; Cluzeau, D.

2002-12-01

The potential influence of earthworms on the mobility of soil inorganic constituents was experimentally investigated. Six 20 cm long and 15 cm i.d. columns were packed with soil (loamy material, Paris basin, France). Three earthworm specimens - Lombricus terrestris - were introduced into 3 of the 6 columns (earthworm treatment or ET), the remaing 3 being used to study changes in water composition and solute fluxes without earthworms (control treatment or CT). The 6 columns were operated for 8 weeks and were subjected to 100 ml addition of distilled water at 1, 8, 15, 22, 29, 36, 43 and 50 days. Effluents were collected weekly, filtered and analysed for their Dissolved Organic Carbon (DOC) as well as Si, Na, K, Mg, Ca, Fe, Mn, Al, Sr, Ba, Cu, Zn, Cr, Cd, REE and U concentrations. Replicates yielded extremely consistent results, with standard deviations generally lower than 10%. Effluent volumes were greatest during ET simulations (28% difference on a cumulative basis), which can be attributed to the construction by Lombricus terrestris of permanent vertical burrows into the soil columns. Different temporal chemical trends were observed depending on whether earthworms were present or not. During ET simulations, a washout phenomenon occurred for DOC, Ca, Mg, Fe, Ba, Sr, Cu and U during the startup outflow period (week 2). This washout was followed by a period of apparent equilibrium with concentrations in ET effluents remaining roughly constant for all solutes except REE, Zn and to a lesser extent Mn. No such washout nor equilibrium period was observed during CT simulations. Instead, concentrations in Ca, Mg, Fe, Ba, Sr, Cr and Cu decreased from week 2 to week 8, while those in other solutes increased from week 2 to week 5, then declining untill week 8. For many elements (not all), final (equilibrium?) concentrations (8 weeks simulation) were highest in ET effluents (e.g. 17% higher for Ca and Na; 30% higher for Zn), despite the enhanced infiltration rate (and thus the likely shorter soil-water interaction time). Although preliminary, these results suggest that earthworm activities can potentialy increase the leaching of a wide variety of inorganic elements in soils. This increase could occur through the ability of earthworms to change the biogeochemical conditions in the soil along their burrows (so-called drilosphere).

Na/Ca Ratio in Large Benthic Foraminifera as a Novel Proxy for Past Ocean Calcium

NASA Astrophysics Data System (ADS)

Rosenthal, Y.; Hauzer, H.; Evans, D.; Erez, J.

2017-12-01

Culture experiments with Operculina ammonoides (a large symbiont bearing benthic foraminifer and an extant relative of the Eocene Nummulites) were carried out varying seawater [Ca], temperature and salinity. The main results of these experiments are: 1. Na/Ca in these foraminifera shells varies with the Na/Ca ratio in the seawater 2. Na/Ca shows small, non-systematic variations with temperature (22-28 ºC) that are within our analytical precision. 3. Na/Ca in the shells show very low changes, increasing linearly with salinity. The sensitivity to salinity is very low compared to that caused by changes of Na/Ca in seawater. Over the seawater experimental range of Na/Ca (10-18 mM), a change of 5 ppt salinity induced a slight Na/Ca increase comparable to the analytical error for Na, or that caused by temperature. Initial reconstructions of seawater [Ca], based on these calibrations, generally agree well with previous models and reconstructions confirming that seawater [Ca] concentrations were substantially higher during the early-mid Cenozoic than today.

NCX-DB: a unified resource for integrative analysis of the sodium calcium exchanger super-family.

PubMed

Bode, Katrin; O'Halloran, Damien M

2018-04-13

Na + /Ca 2+ exchangers are low-affinity high-capacity transporters that mediate Ca 2+ extrusion by coupling Ca 2+ efflux to the influx of Na + ions. The Na + /Ca 2+ exchangers form a super-family comprised of three branches each differing in ion-substrate selectivity: Na + /Ca 2+ exchangers (NCX), Na + /Ca 2+ /K + exchangers, and Ca 2+ /cation exchangers. Their primary function is to maintain Ca 2+ homeostasis and play a particularly important role in excitable cells that experience transient Ca 2+ fluxes. Research into the role and activity of Na + /Ca 2+ exchangers has focused extensively on the cardio-vascular system, however, growing evidence suggests that Na + /Ca 2+ exchangers play a key role in neuronal processes such as memory formation, learning, oligodendrocyte differentiation, neuroprotection during brain ischemia and axon guidance. They have also been implicated in pathologies such as Alzheimer's disease, Parkinson's disease, Multiple Sclerosis and Epilepsy, however, a clear understanding of their mechanism during disease is lacking. To date, there has never been a central resource or database for Na + /Ca 2+ exchangers. With clear disease relevance and ever-increasing research on Na + /Ca 2+ exchangers from both model and non-model species, a database that unifies the data on Na + /Ca 2+ exchangers is needed for future research. NCX-DB is a publicly available database with a web interface that enables users to explore various Na + /Ca 2+ exchangers, perform cross-species sequence comparison, identify new exchangers, and stay-up to date with recent literature. NCX-DB is available on the web via an interactive user interface with an intuitive design, which is applicable for the identification and comparison of Na + /Ca 2+ exchanger proteins across diverse species.

Phase diagram and neutron spin resonance of superconducting NaFe 1 - x Cu x As

DOE PAGES

Tan, Guotai; Song, Yu; Zhang, Rui; ...

2017-02-03

In this paper, we use transport and neutron scattering to study the electronic phase diagram and spin excitations of NaFe 1-xCu xAs single crystals. Similar to Co- and Ni-doped NaFeAs, a bulk superconducting phase appears near x≈2% with the suppression of stripe-type magnetic order in NaFeAs. Upon further increasing Cu concentration the system becomes insulating, culminating in an antiferromagnetically ordered insulating phase near x≈50%. Using transport measurements, we demonstrate that the resistivity in NaFe 1-xCu xAs exhibits non-Fermi-liquid behavior near x≈1.8%. Our inelastic neutron scattering experiments reveal a single neutron spin resonance mode exhibiting weak dispersion along c axis inmore » NaFe 0.98Cu 0.02As. The resonance is high in energy relative to the superconducting transition temperature T c but weak in intensity, likely resulting from impurity effects. These results are similar to other iron pnictides superconductors despite that the superconducting phase in NaFe 1-xCu xAs is continuously connected to an antiferromagnetically ordered insulating phase near x≈50% with significant electronic correlations. Finally, therefore, electron correlations is an important ingredient of superconductivity in NaFe 1-xCu xAs and other iron pnictides.« less

Preparation and structure of Na2Ag5Fe3(P2O7)4 -Ag metal composite: Insights on electrochemistry

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

Zhang, Yiman; Marschilok, Amy C.; Takeuchi, Esther S.

ABSTRACT Ag 7Fe 3(P 2O 7) 4is a 3D structured material which has been recently studied as a possible cathode material for lithium batteries. Notably, Na 7Fe 3(P 2O 7) 4is reported to be a fast-ion conductor, yet poor electrical conductor. Here, partial replacement of Na +for Ag +yielded Na 2Ag 5Fe 3(P 2O 7) 4pyrophosphate framework where the formation of Ag metal is proposed to increase the intrinsic low electrical conductivity of this polyanion electrode. Specifically, the Ag 5Na 2Fe 3(P 2O 7) 4-Ag composite is synthesized via chemical reduction of Ag 7Fe 3(P 2O 7) 4using NaBH 4.more » The occupancy of Ag +and Na +in each site was determined via Rietveld analysis of the diffraction pattern. Electrochemistry of the Ag 5Na 2Fe 3(P 2O 7) 4-Ag metal composite was explored with voltammetry and galvanostatic charge/discharge cycling. The Ag 5Na 2Fe 3(P 2O 7) 4-Ag metal composite electrodes displayed good rate capability assisted by the presence of Ag metal from the chemical reduction and in-situ electrochemical formation of a Ag conductive network.« less

Solid-State Reaction Between Fe-Al-Ca Alloy and Al2O3-CaO-FeO Oxide During Heat Treatment at 1473 K (1200 °C)

NASA Astrophysics Data System (ADS)

Liu, Chengsong; Yang, Shufeng; Li, Jingshe; Ni, Hongwei; Zhang, Xueliang

2017-04-01

The aim of this study was to control the physicochemical characteristics of inclusions in steel through appropriate heat treatment. Using a confocal scanning laser microscope (CSLM) and pipe furnace, the solid-state reactions between Fe-Al-Ca alloy and Al2O3-CaO-FeO oxide during heat treatment at 1473 K (1200 °C) and the influence of these reactions on the compositions of and phases in the alloy and oxide were investigated by the diffusion couple method. Suitable pretreatment of the oxide using a CSLM and production of the diffusion couple of Fe-Al-Ca alloy and Al2O3-CaO-FeO oxide gave good contact between the alloy and oxide. The diffusion couple was then sealed in a quartz tube with a piece of Ti foil to lower oxygen partial pressure and a block of Fe-Al-Ca alloy was introduced to conduct heat treatment experiments. Solid-state reactions between the alloy and oxide during heat treatment at 1473 K (1200 °C) were analyzed and discussed. A dynamic model to calculate the width of the particle precipitation zone based on the Wagner model of internal oxidation of metal was proposed. This model was helpful to understand the solid-state reaction mechanism between Fe-Al-Ca alloy and Al2O3-CaO-FeO oxide.

Effect of exogenous metal ions and mechanical stress on rice processed in thermal-solid enzymatic reaction system related to further alcoholic fermentation efficiency.

PubMed

Xu, Enbo; Wu, Zhengzong; Jiao, Aiquan; Jin, Zhengyu

2018-02-01

Metal-rich thermal-solid enzymatic processing of rice combined with yeast fermentation was investigated. 8 Metal ions were exogenously supplied at 0.05, 0.5 and 5mmol/100g (MG) rice prior to static high pressure enzymatic cooking (HPEC) and dynamic enzymatic extrusion cooking (EEC). Treated rice and its fermentation efficiency (FE) were characterized by rapid viscosity analyzer (RVA), UV-Vis, FT-IR and atomic absorption spectrophotometer (AAS). The optimum pH range of enzyme in solid system (>4.9) was broader than in a liquid system (>5.5). Cations decreased enzymatic activity in HPEC probably due to metal-induced aggregation of rice matrix with reduced reacting area as well as strengthened structure of starch/polysaccharides modified by metals. While using the EEC with mechanical mixing/shearing, relative activity was activated to 110 and 120% by Mg 2+ (0.05-0.5MG) and Ca 2+ (0.05-5MG), respectively. Furthermore, the effectiveness of residual ions to promote further FE was found to follow the order: Ca 2+ >K + >Zn 2+ >Mg 2+ >Mn 2+ >Na + ≈Control>Fe 2+ >Cu 2+ , individually. Copyright © 2017 Elsevier Ltd. All rights reserved.

Na7 [Fe2S6 ] , Na2 [FeS2 ] and Na2 [FeSe2 ] : New 'reduced' sodium chalcogenido ferrates

NASA Astrophysics Data System (ADS)

Stüble, Pirmin; Peschke, Simon; Johrendt, Dirk; Röhr, Caroline

2018-02-01

Three new 'reduced' FeII containing sodium chalcogenido ferrates were obtained applying a reductive synthetic route. The mixed-valent sulfido ferrate Na7 [Fe2S6 ] , which forms bar-shaped crystals with metallic greenish luster, was synthesized in pure phase from natural pyrite and elemental sodium at a maximum temperature of 800 °C. Its centrosymmetric triclinic structure (SG P 1 bar , a = 764.15(2), b = 1153.70(2), c = 1272.58(3) pm, α = 62.3325 (7) , β = 72.8345 (8) , γ = 84.6394 (8) ° , Z = 3, R1 = 0.0185) exhibits two crystallographically different [Fe2S6 ] 7 - dimers of edge-sharing [FeS4 ] tetrahedra, with somewhat larger Fe-S distances than in the fully oxidized FeIII dimers of e.g. Na6 [Fe2III S6 ] . In contrast to the localized AFM ordered pure di-ferrates(III), the Curie-Weiss behavior of the magnetic susceptibility proves the rarely observed valence-delocalized S = 9/2 state of the mixed-valent FeIII /FeII dimer. The nearly spin-only value of the magnetic moment combined with the chemical bonding not generally differing from that in pure ferrates(II) and (III), provides a striking argument, that the reduction of the local Fe spin moments observed in all condensed sulfido ferrate moieties is connected with the AFM spin ordering. The two isotypic ferrates(II) Na2 [FeS2 ] and Na2 [FeSe2 ] with chain-like structural units (SG Ibam, a = 643.54(8)/ 660.81(1), b = 1140.2(2)/1190.30(2) c = 562.90(6)/585.59(1) pm, Z = 4, R1 = 0.0372/0.0466) crystallize in the K2 [ZnO2 ] -type structure. Although representing merely further members of the common series of chalcogenido metallates(II) Na2 [MIIQ2 ] , these two new phases, together with Na6 [FeS4 ] and Li2 [FeS2 ] , are the only examples of pure FeII alkali chalcogenido ferrates. The new compounds allow for a general comparison of di- and chain ferrates(II) and (III) and mixed-valent analogs concerning the electronic and magnetic properties (including Heisenberg super-exchange and double-exchange interactions) based on the comprehensive literature and own DFT band structure calculations.

AGB Sodium Abundances in the Globular Cluster 47 Tucanae (NGC 104)

NASA Astrophysics Data System (ADS)

Johnson, Christian I.; McDonald, Iain; Pilachowski, Catherine A.; Mateo, Mario; Bailey, John I., III; Cordero, Maria J.; Zijlstra, Albert A.; Crane, Jeffrey D.; Olszewski, Edward; Shectman, Stephen A.; Thompson, Ian

2015-02-01

A recent analysis comparing the [Na/Fe] distributions of red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster NGC 6752 found that the ratio of Na-poor to Na-rich stars changes from 30:70 on the RGB to 100:0 on the AGB. The surprising paucity of Na-rich stars on the AGB in NGC 6752 warrants additional investigations to determine if the failure of a significant fraction of stars to ascend the AGB is an attribute common to all globular clusters. Therefore, we present radial velocities, [Fe/H], and [Na/Fe] abundances for 35 AGB stars in the Galactic globular cluster 47 Tucanae (47 Tuc; NGC 104), and compare the AGB [Na/Fe] distribution with a similar RGB sample published previously. The abundances and velocities were derived from high-resolution spectra obtained with the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5 m telescope. We find the average heliocentric radial velocity and [Fe/H] values to be < R{{V}helio.}> = -18.56 km s-1 (σ = 10.21 km s-1) and < [Fe/H]> = -0.68 (σ = 0.08), respectively, in agreement with previous literature estimates. The average [Na/Fe] abundance is 0.12 dex lower in the 47 Tuc AGB sample compared to the RGB sample, and the ratio of Na-poor to Na-rich stars is 63:37 on the AGB and 45:55 on the RGB. However, in contrast to NGC 6752, the two 47 Tuc populations have nearly identical [Na/Fe] dispersion and interquartile range values. The data presented here suggest that only a small fraction (≲20%) of Na-rich stars in 47 Tuc may fail to ascend the AGB, which is a similar result to that observed in M13. Regardless of the cause for the lower average [Na/Fe] abundance in AGB stars, we find that Na-poor stars and at least some Na-rich stars in 47 Tuc evolve through the early AGB phase. The contrasting behavior of Na-rich stars in 47 Tuc and NGC 6752 suggests that the RGB [Na/Fe] abundance alone is insufficient for predicting if a star will ascend the AGB.

AGB sodium abundances in the globular cluster 47 Tucanae (NGC 104)

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

Johnson, Christian I.; McDonald, Iain; Zijlstra, Albert A., E-mail: cjohnson@cfa.harvard.edu, E-mail: iain.mcdonald-2@manchester.ac.uk, E-mail: albert.zijlstra@manchester.ac.uk

A recent analysis comparing the [Na/Fe] distributions of red giant branch (RGB) and asymptotic giant branch (AGB) stars in the Galactic globular cluster NGC 6752 found that the ratio of Na-poor to Na-rich stars changes from 30:70 on the RGB to 100:0 on the AGB. The surprising paucity of Na-rich stars on the AGB in NGC 6752 warrants additional investigations to determine if the failure of a significant fraction of stars to ascend the AGB is an attribute common to all globular clusters. Therefore, we present radial velocities, [Fe/H], and [Na/Fe] abundances for 35 AGB stars in the Galactic globularmore » cluster 47 Tucanae (47 Tuc; NGC 104), and compare the AGB [Na/Fe] distribution with a similar RGB sample published previously. The abundances and velocities were derived from high-resolution spectra obtained with the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan–Clay 6.5 m telescope. We find the average heliocentric radial velocity and [Fe/H] values to be 〈RV{sub helio.}〉 = −18.56 km s{sup −1} (σ = 10.21 km s{sup −1}) and 〈[Fe/H]〉 = −0.68 (σ = 0.08), respectively, in agreement with previous literature estimates. The average [Na/Fe] abundance is 0.12 dex lower in the 47 Tuc AGB sample compared to the RGB sample, and the ratio of Na-poor to Na-rich stars is 63:37 on the AGB and 45:55 on the RGB. However, in contrast to NGC 6752, the two 47 Tuc populations have nearly identical [Na/Fe] dispersion and interquartile range values. The data presented here suggest that only a small fraction (≲20%) of Na-rich stars in 47 Tuc may fail to ascend the AGB, which is a similar result to that observed in M13. Regardless of the cause for the lower average [Na/Fe] abundance in AGB stars, we find that Na-poor stars and at least some Na-rich stars in 47 Tuc evolve through the early AGB phase. The contrasting behavior of Na-rich stars in 47 Tuc and NGC 6752 suggests that the RGB [Na/Fe] abundance alone is insufficient for predicting if a star will ascend the AGB.« less

Experimental and theoretical study of Co sorption in clay montmorillonites

NASA Astrophysics Data System (ADS)

Gil Rebaza, A. V.; Montes, M. L.; Taylor, M. A.; Errico, L. A.; Alonso, R. E.

2018-03-01

Montmorillonite (MMT) clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M = Na, Ca, Fe, etc) in its interlayer space. Depending on the capability for ion sorption, these materials are interesting for environmental remediation. In this work we experimentally study the Co sorption in a natural Na-MMT using UV-visible spectrometry and XRD on semi-oriented samples, and then analyze the sorption ability of this clay by means of ab initio calculation performed on pristine MMT. The structural properties of Na-MMT and Co-adsorbed MMT, and the hyperfine parameters at different atomic sites were analyzed and compared with the experimental ones for the first, and for the case of the hyperfine parameters, presented for the first time for the last. The theoretical predictions based on total energy considerations confirm that Co incorporation replacing Na is energetically favorable. Also, the basal spacing d001 experimentally obtained is well reproduced.

Magnetism in Na-filled Fe-based skutterudites

DOE PAGES

Xing, Guangzong; Fan, Xiaofeng; Zheng, Weitao; ...

2015-06-01

The interplay of superconductivity and magnetism is a subject of ongoing interest, stimulated most recently by the discovery of Fe-based superconductivity and the recognition that spin-fluctuations near a magnetic quantum critical point may provide an explanation for the superconductivity and the order parameter. We investigate magnetism in the Na filled Fe-based skutterudites using first principles calculations. NaFe 4Sb 12 is a known ferromagnet near a quantum critical point. We find a ferromagnetic metallic state for this compound driven by a Stoner type instability, consistent with prior work. In accord with prior work, the magnetization is overestimated, as expected for amore » material near an itinerant ferromagnetic quantum critical point. NaFe 4P 12 also shows a ferromagnetic instability at the density functional level, but this instability is much weaker than that of NaFe 4Sb 12, possibly placing it on the paramagnetic side of the quantum critical point. NaFe 4As 12 shows intermediate behavior. We also present results for skutterudite FeSb 3, which is a metastable phase that has been reported in thin film form.« less

Characteristics of Catalytic Gasification of Natural Coke with H2O in a Fluidized Bed

NASA Astrophysics Data System (ADS)

Lin, L. S.; Zhao, C. S.; Wang, S.; Zhu, G.; Xiang, W. G.

The experimental investigation on gasification characteristics of natural coke from Peicheng, Jiangsu with steam were conducted in a fluidized bed gasifier setup. The effects of several parameters, in terms of the catalyst type, the catalyst mixed manner and the dosage of catalyst over coke on the yield, the components, the heating value of fuel gas and the carbon conversion rate were examined. Results indicate that the fluidized bed gasification technology could overcome the shortcomings of natural coke. Ca-, Fe- and Cu-based nitrates could improve the gasification reaction effectively with a little difference, they could be listed in a descending sequence as follows: Cu-based>Fe-based>Ca-based according to their catalytic effect. The influences of Fe/Ca ratio and Cu/Ca ratio on gasification are similar, gas yield, carbon conversion rate and gas heating value per hour increase as Fe/Ca ratio or Cu/Ca ratio increases, but all of them go up first and then drop with decrease in Fe/Cu ratio. When the dosage of Ca-, Fe- and Cu-based nitrates mixed with the ratio of Ca/Fe/Cu= 10/35/55 is 3%, the best catalytic effect is achieved.

Fabrication of CaFe2O4 nanofibers via electrospinning method with enhanced visible light photocatalytic activity

NASA Astrophysics Data System (ADS)

Wang, Jianmin; Wang, Yunan; Liu, Yinglei; Li, Song; Cao, Feng; Qin, Gaowu

CaFe2O4 nanofibers with diameters of about 130nm have been fabricated via a facile electrospinning method. The structures, morphologies and optical properties of the obtained CaF2O4 nanofibers have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Visible UV-Vis diffuse reflectance spectrum. The photocatalytic activities of the CaFe2O4 nanofibers are evaluated by the photo-degradation of Methyl orange (MO). The results show that the CaFe2O4 nanofibers (72%) exhibit much higher photocatalytic performance than the CaFe2O4 powders (27%) prepared by conventional method under visible light irradiation. The enhanced photocatalytic performance of CaFe2O4 nanofibers could be attributed to the large surface area, high photogenerated charge carriers density and low charge transfer resistance, as revealed by photoelectrochemical measurement. And fundamentally, it could be attributed to the decreased particle size and the fibrous nanostructure. This work not only provides an efficient way to improve the photocatalytic activity of CaFe2O4, but also provides a new method for preparing materials with nanofibrous structure.

2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}

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

Guo, Haichuan; Hosaka, Yoshiteru; Seki, Hayato

La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{submore » 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.« less

Geochemical element mobility during the hydrothermal alteration in the Tepeoba porphyry Cu-Mo-Au deposits at Balikesir, NW Turkey

NASA Astrophysics Data System (ADS)

Abdelnasser, Amr; Kiran Yildirim, Demet; Doner, Zeynep; Kumral, Mustafa

2016-04-01

The Tepeoba porphyry Cu-Mo-Au deposit represents one of the important copper source and mineral deposits in the Anatolian tectonic belt at Balikesir province, NW Turkey. It considered as a vein-type deposit locally associated with intense hydrothermal alteration within the brecciation, quartz stockwork veining, and brittle fracture zones in the main host rock that represented by hornfels, as well as generally related to the shallow intermediate to silicic intrusive Eybek pluton. Based on the field and geologic relationships and types of ore mineral assemblages and the accompanied alteration types, there are two mineralization zones; hypogene (primary) and oxidation/supergene zones are observed associated with three alteration zones; potassic, phyllic, and propylitic zones related to this porphyry deposit. The phyllic and propylitic alterations locally surrounded the potassic alteration. The ore minerals related to the hypogene zone represented by mostly chalcopyrite, Molybdenite, and pyrite with subordinate amount of marcasite, enargite, and gold. On the other hand they include mainly cuprite with chalcopyrite, pyrite and gold as well as hematite and goethite at the oxidation/supergene zone. This study deals with the quantitative calculations of the mass/volume changes (gains and losses) of the major and trace elements during the different episodes of alteration in this porphyry deposit. These mass balance data reveal that the potassic alteration zone that the main Cu- and Mo-enriched zone, has enrichment of K, Si, Fe, and Mg, and depletion of Na referring to replacement of plagioclase and amphibole by K-feldspar, sericite and biotite. While the propylitic alteration that is the main Mo- and Au-enriched zone is accompanied with K and Na depletion with enrichment of Si, Fe, Mg, and Ca forming chlorite, epidote, carbonate and pyrite. On the other hand the phyllic alteration that occurred in the outer part around the potassic alteration, characterized by less amount of Cu and Mo mineralization having addition of Si and K with removal of Fe, Mg, Ca, and Na. Keywords: Mass balance calculation; Tepeoba porphyry Cu-Mo-Au deposits; Balikesir; Turkey

Deposition of vaporized species onto glassy fallout from a near-surface nuclear test

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

Weisz, David G.; Jacobsen, Benjamin; Marks, Naomi E.

In a near-surface nuclear explosion where the resultant fireball can interact with the surface, vaporized materials from the nuclear device can be incorporated into molten soil and other carrier materials from that surface. This mixed material becomes a source of glassy fallout upon quenching and is locally deposited. Fallout formation models have been proposed; however, the specific mechanisms and physical conditions by which soil and other carrier materials interact in the fireball, as well as the subsequent incorporation of device materials with carrier materials, are not well constrained. We observe a surface deposition layer preserved at interfaces where two aerodynamicmore » fallout glasses agglomerated and fused, and characterized 11 such boundaries using spatial analyses to better understand the vaporization and condensation behavior of species in the fireball. Using nanoscale secondary ion mass spectrometry (NanoSIMS), we identify higher enrichments of uranium from the device ( 235U/ 238U ratio >7.5) in 8 of the interface layers. Major element analysis of the interfaces reveals the deposition layer to be enriched in Fe, Ca, Mg, Mn, and Na-bearing species and depleted in Ti and Al-bearing species. Most notably, the Fe and Ca-bearing species are enriched approximately 50% at the interface layer relative to the average concentrations measured within the fallout glasses, while Ti and Al-bearing species are depleted by approximately 20%. SiO 2 is found to be relatively invariable across the samples and interfaces (~3% standard deviation). The notable depletion of Al, a refractory oxide abundant in the soil, together with the enrichment of 235U and Fe, suggests an anthropogenic source of the enriched species or an unexpected vaporization/condensation behavior. The presence of both refractory (e.g., Ca and U) and volatile (e.g., Na) species approximately co-located in most of the observed layers (within 1.5 μm) suggests a continuous condensation process may also be occurring. Lastly, these fallout formation processes deviate from historical models of fallout formation, and have not been previously recognized in the literature.« less

Multicomponent diffusion in basaltic melts at 1350 °C

NASA Astrophysics Data System (ADS)

Guo, Chenghuan; Zhang, Youxue

2018-05-01

Nine successful diffusion couple experiments were conducted in an 8-component SiO2-TiO2-Al2O3-FeO-MgO-CaO-Na2O-K2O system at ∼1350 °C and at 1 GPa, to study multicomponent diffusion in basaltic melts. At least 3 traverses were measured to obtain diffusion profiles for each experiment. Multicomponent diffusion matrix at 1350 °C was obtained by simultaneously fitting diffusion profiles of diffusion couple experiments. Furthermore, in order to better constrain the diffusion matrix and reconcile mineral dissolution data, mineral dissolution experiments in the literature and diffusion couple experiments from this study, were fit together. All features of diffusion profiles in both diffusion couple and mineral dissolution experiments were well reproduced by the diffusion matrix. Diffusion mechanism is inferred from eigenvectors of the diffusion matrix, and it shows that the diffusive exchange between network-formers SiO2 and Al2O3 is the slowest, the exchange of SiO2 with other oxide components is the second slowest with an eigenvalue that is only ∼10% larger, then the exchange between divalent oxide components and all the other oxide components is the third slowest with an eigenvalue that is twice the smallest eigenvalue, then the exchange of FeO + K2O with all the other oxide components is the fourth slowest with an eigenvalue that is 5 times the smallest eigenvalue, then the exchange of MgO with FeO + CaO is the third fastest with an eigenvalue that is 6.3 times the smallest eigenvalue, then the exchange of CaO + K2O with all the other oxide components is the second fastest with an eigenvalue that is 7.5 times the smallest eigenvalue, and the exchange of Na2O with all other oxide components is the fastest with an eigenvalue that is 31 times the smallest eigenvalue. The slowest and fastest eigenvectors are consistent with those for simpler systems in most literature. The obtained diffusion matrix was successfully applied to predict diffusion profiles during mineral dissolution in basaltic melts.

Deposition of vaporized species onto glassy fallout from a near-surface nuclear test

NASA Astrophysics Data System (ADS)

Weisz, David G.; Jacobsen, Benjamin; Marks, Naomi E.; Knight, Kim B.; Isselhardt, Brett H.; Matzel, Jennifer E.; Weber, Peter K.; Prussin, Stan G.; Hutcheon, Ian D.

2017-03-01

In a near-surface nuclear explosion where the resultant fireball can interact with the surface, vaporized materials from the nuclear device can be incorporated into molten soil and other carrier materials from that surface. This mixed material becomes a source of glassy fallout upon quenching and is locally deposited. Fallout formation models have been proposed; however, the specific mechanisms and physical conditions by which soil and other carrier materials interact in the fireball, as well as the subsequent incorporation of device materials with carrier materials, are not well constrained. We observe a surface deposition layer preserved at interfaces where two aerodynamic fallout glasses agglomerated and fused, and characterized 11 such boundaries using spatial analyses to better understand the vaporization and condensation behavior of species in the fireball. Using nanoscale secondary ion mass spectrometry (NanoSIMS), we identify higher enrichments of uranium from the device (235U/238U ratio >7.5) in 8 of the interface layers. Major element analysis of the interfaces reveals the deposition layer to be enriched in Fe, Ca, Mg, Mn, and Na-bearing species and depleted in Ti and Al-bearing species. Most notably, the Fe and Ca-bearing species are enriched approximately 50% at the interface layer relative to the average concentrations measured within the fallout glasses, while Ti and Al-bearing species are depleted by approximately 20%. SiO2 is found to be relatively invariable across the samples and interfaces (∼3% standard deviation). The notable depletion of Al, a refractory oxide abundant in the soil, together with the enrichment of 235U and Fe, suggests an anthropogenic source of the enriched species or an unexpected vaporization/condensation behavior. The presence of both refractory (e.g., Ca and U) and volatile (e.g., Na) species approximately co-located in most of the observed layers (within 1.5 μm) suggests a continuous condensation process may also be occurring. These fallout formation processes deviate from historical models of fallout formation, and have not been previously recognized in the literature.

Zoned chondrules in Semarkona: Evidence for high-and low-temperature processing

USGS Publications Warehouse

Grossman, J.N.; Alexander, C.M. O'D.; Wang, Jingyuan; Brearley, A.J.

2002-01-01

At least 15% of the low-FeO chondrules in Semarkona (LL3.0) have mesostases that are concentrically zoned in Na, with enrichments near the outer margins. We have studied zoned chondrules using electron microprobe methods (x-ray mapping plus quantitative analysis), ion micropobe analysis for trace elements and hydrogen isotopes, cathodoluminescence imaging, and transmission electron microscopy in order to determine what these objects can tell us about the environment in which chondrules formed and evolved. Mesostases in these chondrules are strongly zoned in all moderately volatile elements and H (interpreted as water). Calcium is depleted in areas of volatile enrichment. Titanium and Cr generally decrease toward the chondrule surfaces, whereas Al and Si may either increase or decrease, generally in opposite directions to one another; Mn follows Na in some chondrules but not in others; Fe and Mg are unzoned. D/H ratios increase in the water-rich areas of zoned chondrules. Mesostasis shows cathodoluminescence zoning in most zoned chondrules, with the brightest yellow color near the outside. Mesostasis in zoned chondrules appears to be glassy, with no evidence for devitrification. Systematic variations in zoning patterns among pyroxene- and olivine-rich chondrules may indicate that fractionation of low- and high-Ca pyroxene played some role in Ti, Cr, Mn, Si, Al, and some Ca zoning. But direct condensation of elements into hot chondrules, secondary melting of late condensates into the outer portions of chondrules, and subsolidus diffusion of elements into warm chondrules cannot account for the sub-parallel zoning profiles of many elements, the presence of H2O, or elemental abundance patterns. Zoning of moderately volatile elements and Ca may have been produced by hydration of chondrule glass without devitrification during aqueous alteration on the parent asteroid. This could have induced structural changes in the glass allowing rapid diffusion and exchange of elements between altered glass and surrounding matrix and rim material. Calcium was mainly lost during this process, and other nonvolatile elements may have been mobile as well. Some unzoned, low-FeO chondrules appear to have fully altered mesostasis.

[Application of multivariate analysis to the serum mineral and trace element content on differentiation of healthy subjects].

PubMed

Rodríguez Rodríguez, E; Henríquez Sánchez, P; López Blanco, F; Díaz Romero, C; Serra Majem, L

2004-01-01

Serum concentrations of Na, K, Ca, Mg, Fe, Cu, Zn, Se, Mn and P were determined in apparently health individuals representing of the population of the Canary Islands. Multivariate analysis was applied on the data matrix in order to differentiate the individuals according several criteria such as gender, age, island and province of residence, smoking and drinking habits and physical exercise. 395 serum samples (187 men and 208 women) were analyzed mean age of 38.4 +/- 20.0 years. Individuals data about age, gender, weight, height, alcohol consumption, smoking habits and physical exercise were recorded using standardized questionnaires. The determination of minerals was carried out by flame emission spectrometry (Na and K) and atomic absorption spectrometry with flame air/acetylene (Ca, Mg, Fe, Cu, Zn), hybride generation (Se) and graphite furnace (Mn). The P was determined by a colorimetric method. The sex and age of individuals influenced on the serum concentrations of some minerals, Cu and Fe, and P and Se, respectively. The island of residence influenced the mean concentrations of the most the minerals analysed. The smoking and drinking habits do not seem to influence the mean contents of the minerals in an important manner. Physical exercise had significant influence on the P, Cu and Mn concentrations in serum. The water for consumption influenced on the serum concentrations of the electrolytes and Ca and Mg, but it did not affect the concentrations of the trace elements. Applying discriminant analysis the individuals lower 18 years were reasonably well differentiated (89% of the individuals correctly classified) from the rest of individuals. A tendency for differentiation of individuals according to the island of residence was also observed. A low differentiation of the individuals according to the sex, province or island or residence and habits or life style was observed after application of multivariate analysis techniques. However, the adults were reasonably differentiated from the children and adolescent, and the inhabitants of Lanzarote and La Palma tend to separate from the rest of the individuals of their province.

Deposition of vaporized species onto glassy fallout from a near-surface nuclear test

DOE PAGES

Weisz, David G.; Jacobsen, Benjamin; Marks, Naomi E.; ...

2016-10-29

In a near-surface nuclear explosion where the resultant fireball can interact with the surface, vaporized materials from the nuclear device can be incorporated into molten soil and other carrier materials from that surface. This mixed material becomes a source of glassy fallout upon quenching and is locally deposited. Fallout formation models have been proposed; however, the specific mechanisms and physical conditions by which soil and other carrier materials interact in the fireball, as well as the subsequent incorporation of device materials with carrier materials, are not well constrained. We observe a surface deposition layer preserved at interfaces where two aerodynamicmore » fallout glasses agglomerated and fused, and characterized 11 such boundaries using spatial analyses to better understand the vaporization and condensation behavior of species in the fireball. Using nanoscale secondary ion mass spectrometry (NanoSIMS), we identify higher enrichments of uranium from the device ( 235U/ 238U ratio >7.5) in 8 of the interface layers. Major element analysis of the interfaces reveals the deposition layer to be enriched in Fe, Ca, Mg, Mn, and Na-bearing species and depleted in Ti and Al-bearing species. Most notably, the Fe and Ca-bearing species are enriched approximately 50% at the interface layer relative to the average concentrations measured within the fallout glasses, while Ti and Al-bearing species are depleted by approximately 20%. SiO 2 is found to be relatively invariable across the samples and interfaces (~3% standard deviation). The notable depletion of Al, a refractory oxide abundant in the soil, together with the enrichment of 235U and Fe, suggests an anthropogenic source of the enriched species or an unexpected vaporization/condensation behavior. The presence of both refractory (e.g., Ca and U) and volatile (e.g., Na) species approximately co-located in most of the observed layers (within 1.5 μm) suggests a continuous condensation process may also be occurring. Lastly, these fallout formation processes deviate from historical models of fallout formation, and have not been previously recognized in the literature.« less

[Evaluation of compounding EDTA and citric acid on remediation of heavy metals contaminated soil].

PubMed

Yin, Xue; Chen, Jia-Jun; Cai, Wen-Min

2014-08-01

As commonly used eluents, Na2EDTA (EDTA) and citric acid (CA) have been widely applied in remediation of soil contaminated by heavy metals. In order to evaluate the removal of arsenic, cadmium, copper, and lead in the contaminated soil collected in a chemical plant by compounding EDTA and CA, a series of stirring experiments were conducted. Furthermore, the changes in speciation distribution of heavy metals before and after washing were studied. The results showed that, adopting the optimal molar ratio of EDTA/CA (1:1), when the pH of the solution was 3, the stirring time was 30 min, the stirring rate was 150 r x min(-1) and the L/S was 5:1, the removal rates of arsenic, cadmium, copper and lead could reach 11.72%, 43.39%, 24.36% and 27.17%, respectively. And it was found that after washing, for arsenic and copper, the content of acid dissolved fraction rose which increased the percentage of available contents. Fe-Mn oxide fraction mainly contributed to the removal of copper. As for cadmium, the percentages of acid dissolved fraction, Fe-Mn oxide fraction and organic fraction also decreased. In practical projects, speciation changes would pose certain environmental risk after soil washing, which should be taken into consideration.

First-principles calculations for XAS of infinite-layer iron oxides

NASA Astrophysics Data System (ADS)

Kodera, Mitsuru; Shishidou, Tatsuya; Oguchi, Tamio

2011-03-01

The oxygen defect perovskite SrFe O3 - x shows various properties such as the giant magnetoresistance effect and the thermoelectric effect. It had been believed that the oxygen content in SrFe O3 - x changes up to x = 0.5 . Recently, Tsujimoto et al . have succeeded in synthesizing the infinite-layer iron oxide SrFe O2 . SrFe O2 has a square-planar oxygen coordination, while the iron oxides usually have the tetrahedral and octahedral coordination. CaFe O2 has also infinite layer structure and the same magnetic ordering as SrFe O2 . However, it is suggested that the oxygen coordination of CaFe O2 is different from that of SrFe O2 . In order to investigate the electronic structure of iron in (Ca, Sr) Fe O2 , the x-ray absorption spectroscopy (XAS) spectrum has been measured. In this work, we perform the calculation for XAS spectrum near the Fe-K edge of (Ca, Sr) Fe O2 using the first-principles calculations. We compare the results with the experiment and discuss the electronic structure of iron in (Ca, Sr) Fe O2 .

Sensitive and selective detection of trivalent chromium using Hyper Rayleigh Scattering with 5,5'-dithio-bis-(2-nitrobenzoic acid)-modified gold nanoparticles.

PubMed

Hughes, Shantelle I; Dasary, Samuel S R; Singh, Anant K; Glenn, Zachery; Jamison, Hakim; Ray, Paresh C; Yu, Hongtao

2013-03-01

Hyper Rayleigh Scattering (HRS) and absorption spectral assays using surface-modified gold nanoparticles (AuNP) have been developed for sensitive and selective detection of trivalent chromium (Cr 3+ ) from other metal ions including hexavalent chromium (as Cr 2 O 7 2- ). Gold nanoparticles of 13 nm, covalently attached with 5,5'-dithio- bis -(2-nitrobenzoic acid) (AuNP-DTNBA), is used as a probe for both the absorption and HRS assays. AuNP-DTNBA is able to detect Cr 3+ at 20 ppb level at pH 6.0 using absorption spectral change of the AuNP-DTNBA. Visible color change can be observed when mixed with 250 ppb of Cr 3+ , while there is no color change when mixed with 2 ppm level of some of the most common metal ions such as Cr 2 O 7 2- , Hg 2+ , Ba 2+ , Fe 3+ , Pb 2+ , Na + , Zn 2+ , Cd 2+ , Co 2+ , Mn 2+ , Ca 2+ , and Ni 2+ . However, a color change is observed when mixed with Ni 2+ , Zn 2+ , and Cd 2+ at a concentration higher than 2 ppm. The detection limit for the HRS assay is on a remarkable 25 ppt level, and there is no detectable HRS signal at 2 ppm level for Cr 2 O 7 2- , Hg 2+ , Ba 2+ , Fe 3+ , Pb 2+ , Na + , Zn 2+ , Cd 2+ , Co 2+ , Mn 2+ , Ca 2+ , and Ni 2+ .

Are more environmentally sustainable diets with less meat and dairy nutritionally adequate?

PubMed

Seves, S Marije; Verkaik-Kloosterman, Janneke; Biesbroek, Sander; Temme, Elisabeth Hm

2017-08-01

Our current food consumption patterns, and in particular our meat and dairy intakes, cause high environmental pressure. The present modelling study investigates the impact of diets with less or no meat and dairy foods on nutrient intakes and assesses nutritional adequacy by comparing these diets with dietary reference intakes. Environmental impact and nutrient intakes were assessed for the observed consumption pattern (reference) and two replacement scenarios. For the replacement scenarios, 30 % or 100 % of meat and dairy consumption (in grams) was replaced with plant-based alternatives and nutrient intakes, greenhouse gas emissions and land use were calculated. The Netherlands. Dutch adults (n 2102) aged 19-69 years. Replacing 30 % of meat and dairy with plant-based alternatives did not substantially alter percentages below the Estimated Average Requirement (EAR) for all studied nutrients. In the 100 % replacement scenario, SFA intake decreased on average by ~35 % and Na intake by ~8 %. Median Ca intakes were below the Adequate Intake. Estimated habitual fibre, Fe and vitamin D intakes were higher; however, non-haem Fe had lower bioavailability. For Zn, thiamin and vitamin B12, 10-31 % and for vitamin A, 60 % of adults had intakes below the EAR. Diets with all meat and dairy replaced with plant-based foods lowered environmental impacts by >40 %. Estimated intakes of Zn, thiamin, vitamins A and B12, and probably Ca, were below recommendations. Replacing 30 % was beneficial for SFA, Na, fibre and vitamin D intakes, neutral for other nutrients, while reducing environmental impacts by 14 %.

A field study to evaluate runoff quality from green roofs.

PubMed

Vijayaraghavan, K; Joshi, U M; Balasubramanian, R

2012-03-15

Green (vegetated) roofs are emerging as practical strategies to improve the environmental quality of cities. However, the impact of green roofs on the storm water quality remains a topic of concern to city planners and environmental policy makers. This study investigated whether green roofs act as a source or a sink of various metals (Na, K, Ca, Mg, Al, Fe, Cu, Cd, Pb, Zn, Mn, Cr, Ni, Li and Co), inorganic anions (NO3-, NO2-, PO4(3-), SO4(2-), Cl-, F- and Br-) and cation (NH4+). A series of green roof assemblies were constructed. Four different real rain events and several artificial rain events were considered for the study. Results showed that concentrations of most of the chemical components in runoff were highest during the beginning of rain events and subsided in the subsequent rain events. Some of the important components present in the runoff include Na, K, Ca, Mg, Li, Fe, Al, Cu, NO3-, PO4(3-) and SO4(2-). However, the concentration of these chemical components in the roof runoff strongly depends on the nature of substrates used in the green roof and the volume of rain. Based on the USEPA standards for freshwater quality, we conclude that the green roof used in this study is reasonably effective except that the runoff contains significant amounts of NO3- and PO4(3-). Copyright © 2011 Elsevier Ltd. All rights reserved.

Level of minerals and trace elements in the urine of the participants of mountain ultra-marathon race.

PubMed

Jablan, Jasna; Inić, Suzana; Stosnach, Hagen; Hadžiabdić, Maja Ortner; Vujić, Lovorka; Domijan, Ana-Marija

2017-05-01

The aim of the present study was to explore impact of endurance exercise on urinary level of minerals and trace elements as well as on some oxidative stress and biochemical parameters. Urine samples were collected from participants (n=21) of mountain ultra-marathon race (53km; Medvednica, Zagreb, Croatia), before (baseline value), immediately after, 12h and 24h after the race. In urine samples level of minerals (Ca, P, K and Na) and trace elements (Se, Zn, Mn, Cu, Fe and Co) were assessed using the bench top Total reflection X-ray Fluorescence (TXRF) spectrometer. Oxidative stress was determined as level of malondialdehyde (MDA). Immediately after the race level of minerals, trace elements, MDA, creatinine, ketones, erythrocytes and specific gravity increased compared to their baseline value. In 24h follow-up trace elements involved in antioxidant defence, MDA and biochemical parameters returned to their baseline values, Cu and Co remained increased as after the race, Fe and K tended to return to baseline values while Ca, P and Na continued to increase. Mountain ultra-marathon resulted in alteration of physiologically important minerals and trace elements that for some minerals and trace elements persist, indicating their involvement in recovery processes. However, due to their loss in urine, level of minerals and trace elements in athletes participating in endurance exercise should be monitored. Copyright © 2017 Elsevier GmbH. All rights reserved.

Photocatalytic activity of Fe-doped CaTiO₃ under UV-visible light.

PubMed

Yang, He; Han, Chong; Xue, Xiangxin

2014-07-01

The photocatalytic degradation of methylene blue (MB) over Fe-doped CaTiO₃ under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) system, Fourier transform infrared spectra (FT-IR), and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO₃ in the visible light region. The Fe-doped CaTiO₃ exhibited higher photocatalytic activity than CaTiO₃ for the degradation of MB. However, the photocatalytic activity of the Fe-doped CaTiO₃ was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO₃ prepared at 500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB (10ppm) under UV-visible light for 180 min. Copyright © 2014. Published by Elsevier B.V.

Mineral Analysis of Pine Nuts (Pinus spp.) Grown in New Zealand

PubMed Central

Vanhanen, Leo P.; Savage, Geoffrey P.

2013-01-01

Mineral analysis of seven Pinus species grown in different regions of New Zealand; Armand pine (Pinus armandii Franch), Swiss stone pine (Pinus cembra L.), Mexican pinyon (Pinus cembroides Zucc. var. bicolor Little), Coulter pine (Pinus coulteri D. Don), Johann’s pine (Pinus johannis M.F. Robert), Italian stone pine (Pinus pinea L.) and Torrey pine (Pinus torreyana Parry ex Carrière), was carried out using an inductively coupled plasma optical emission spectrophotometer (ICP-OES) analysis. Fourteen different minerals (Al, B, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S and Zn) were identified in all seven varieties, except that no Al or Na was found in Pinus coulteri D. Don. New Zealand grown pine nuts are a good source of Cu, Mg, Mn, P and Zn, meeting or exceeding the recommended RDI for these minerals (based on an intake of 50 g nuts/day) while they supplied between 39%–89% of the New Zealand RDI for Fe. Compared to other commonly eaten tree-nuts New Zealand grown pine nuts are an excellent source of essential minerals. PMID:28239104

Mineral Analysis of Pine Nuts (Pinus spp.) Grown in New Zealand.

PubMed

Vanhanen, Leo P; Savage, Geoffrey P

2013-04-03

Mineral analysis of seven Pinus species grown in different regions of New Zealand; Armand pine ( Pinus armandii Franch), Swiss stone pine ( Pinus cembra L.), Mexican pinyon ( Pinus cembroides Zucc. var. bicolor Little), Coulter pine ( Pinus coulteri D. Don), Johann's pine ( Pinus johannis M.F. Robert), Italian stone pine ( Pinus pinea L.) and Torrey pine ( Pinus torreyana Parry ex Carrière), was carried out using an inductively coupled plasma optical emission spectrophotometer (ICP-OES) analysis. Fourteen different minerals (Al, B, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, S and Zn) were identified in all seven varieties, except that no Al or Na was found in Pinus coulteri D. Don. New Zealand grown pine nuts are a good source of Cu, Mg, Mn, P and Zn, meeting or exceeding the recommended RDI for these minerals (based on an intake of 50 g nuts/day) while they supplied between 39%-89% of the New Zealand RDI for Fe. Compared to other commonly eaten tree-nuts New Zealand grown pine nuts are an excellent source of essential minerals.

Comparison of rapid methods for chemical analysis of milligram samples of ultrafine clays

USGS Publications Warehouse

Rettig, S.L.; Marinenko, J.W.; Khoury, Hani N.; Jones, B.F.

1983-01-01

Two rapid methods for the decomposition and chemical analysis of clays were adapted for use with 20–40-mg size samples, typical amounts of ultrafine products (≤0.5-µm diameter) obtained by modern separation methods for clay minerals. The results of these methods were compared with those of “classical” rock analyses. The two methods consisted of mixed lithium metaborate fusion and heated decomposition with HF in a closed vessel. The latter technique was modified to include subsequent evaporation with concentrated H2SO4 and re-solution in HCl, which reduced the interference of the fluoride ion in the determination of Al, Fe, Ca, Mg, Na, and K. Results from the two methods agree sufficiently well with those of the “classical” techniques to minimize error in the calculation of clay mineral structural formulae. Representative maximum variations, in atoms per unit formula of the smectite type based on 22 negative charges, are 0.09 for Si, 0.03 for Al, 0.015 for Fe, 0.07 for Mg, 0.03 for Na, and 0.01 for K.

Na+ channel regulation by Ca2+/calmodulin and Ca2+/calmodulin-dependent protein kinase II in guinea-pig ventricular myocytes†

PubMed Central

Aiba, Takeshi; Hesketh, Geoffrey G.; Liu, Ting; Carlisle, Rachael; Villa-Abrille, Maria Celeste; O'Rourke, Brian; Akar, Fadi G.; Tomaselli, Gordon F.

2010-01-01

Aims Calmodulin (CaM) regulates Na+ channel gating through binding to an IQ-like motif in the C-terminus. Ca2+/CaM-dependent protein kinase II (CaMKII) regulates Ca2+ handling, and chronic overactivity of CaMKII is associated with left ventricular hypertrophy and dysfunction and lethal arrhythmias. However, the acute effects of Ca2+/CaM and CaMKII on cardiac Na+ channels are not fully understood. Methods and results Purified NaV1.5–glutathione-S-transferase fusion peptides were phosphorylated in vitro by CaMKII predominantly on the I–II linker. Whole-cell voltage-clamp was used to measure Na+ current (INa) in isolated guinea-pig ventricular myocytes in the absence or presence of CaM or CaMKII in the pipette solution. CaMKII shifted the voltage dependence of Na+ channel availability by ≈+5 mV, hastened recovery from inactivation, decreased entry into intermediate or slow inactivation, and increased persistent (late) current, but did not change INa decay. These CaMKII-induced changes of Na+ channel gating were completely abolished by a specific CaMKII inhibitor, autocamtide-2-related inhibitory peptide (AIP). Ca2+/CaM alone reproduced the CaMKII-induced changes of INa availability and the fraction of channels undergoing slow inactivation, but did not alter recovery from inactivation or the magnitude of the late current. Furthermore, the CaM-induced changes were also completely abolished by AIP. On the other hand, cAMP-dependent protein kinase A inhibitors did not abolish the CaM/CaMKII-induced alterations of INa function. Conclusion Ca2+/CaM and CaMKII have distinct effects on the inactivation phenotype of cardiac Na+ channels. The differences are consistent with CaM-independent effects of CaMKII on cardiac Na+ channel gating. PMID:19797425

Report: antioxidant and nutraceutical value of wild medicinal Rubus berries.

PubMed

Ahmad, Mushtaq; Masood, Saima; Sultana, Shazia; Hadda, Taibi Ben; Bader, Ammar; Zafar, Muhammad

2015-01-01

Nutritional quality and antioxidant capacity of three edible wild berries (Rubus ellipticus Smith, Rubus niveus Thunb, Rubus ulmifolius L.) from Lesser Himalayan Range (LHR) were evaluated. Their edible portion was assayed for moisture, fats, ash, carbohydrates, proteins, fibers, essential minerals (Ca, P, Mg, K, Na, Cl, S, Mn, Zn, Fe, Cu, Se, Co, Ni) and DPPH free radical scavenging activity was applied to determine the antioxidant potential. The fruit of Rubus ulmifolius L. (blackberry) possessed the highest values of energy (403.29 Kcal), total protein (6.56g/100 g), Nitrogen (N) content (1500mg/100g), K (860.17mg/100g), Ca (620.56mg/100g), Zn (17.509mg/100g) and the strongest antioxidant activity (98.89% inhibition). While the raspberries (Rubus ellipticus Smith, Rubus niveus Thunb.) exhibited more significant contents of dietary fiber (5.90g/100g), carbohydrates (86.4 g/100 g) and Fe (4.249mg/100g). Significant variation was observed among the tested samples in all the investigated features. The combination of bio elements and active antioxidants clearly showed the applicability of these berries as a nutraceutical supplement.

REE partitioning between apatite and melt in a peralkaline volcanic suite, Kenya Rift Valley

USGS Publications Warehouse

Macdonald, R.; Baginski, B.; Belkin, H.E.; Dzierzanowski, P.; Jezak, L.

2009-01-01

Electron microprobe analyses are presented for fluorapatite phenocrysts from a benmoreite-peralkaline rhyolite volcanic suite from the Kenya Rift Valley. The rocks have previously been well characterized petrographically and their crystallization conditions are reasonably well known. The REE contents in the M site increase towards the rhyolites, with a maximum britholite component of ~35 mol.%. Chondrite-normalized REE patterns are rather flat between La and Sm and then decrease towards Yb. Sodium and Fe occupy up to 1% and 4%, respectively, of the M site. The major coupled substitution is REE3+ + Si4+ ??? Ca2+ + P5+. The substitution REE3+ + Na+ ??? 2Ca2+ has been of minor importance. The relatively large Fe contents were perhaps facilitated by the low fo2 conditions of crystallization. Zoning is ubiquitous and resulted from both fractional crystallization and magma mixing. Apatites in some rhyolites are relatively Y-depleted, perhaps reflecting crystallization from melts which had precipitated zircon. Mineral/glass (melt) ratios for two rhyolites are unusually high, with maxima at Sm (762, 1123). ?? 2008 The Mineralogical Society.

Coexistence of superconductivity and magnetism in Ca1 -xNaxFe2As2 : Universal suppression of the magnetic order parameter in 122 iron pnictides

NASA Astrophysics Data System (ADS)

Materne, Philipp; Kamusella, Sirko; Sarkar, Rajib; Goltz, Til; Spehling, Johannes; Maeter, Hemke; Harnagea, Luminita; Wurmehl, Sabine; Büchner, Bernd; Luetkens, Hubertus; Timm, Carsten; Klauss, Hans-Henning

2015-10-01

We present a detailed investigation of the magnetic and superconducting properties of Ca1 -xNaxFe2As2 single crystals with x =0.00 , 0.35, 0.50, and 0.67 by means of the local probe techniques Mössbauer spectroscopy and muon spin relaxation experiments. With increasing Na-substitution level, the magnetic order parameter is suppressed. For x =0.50 we find a microscopic coexistence of magnetic and superconducting phases accompanied by a reduction of the magnetic order parameter below the superconducting transition temperature Tc. A systematic comparison with other 122 pnictides reveals a square-root correlation between the reduction of the magnetic order parameter and the ratio of the transition temperatures Tc/TN , which can be understood in the framework of a Landau theory. In the optimally doped sample with Tc≈34 K, diluted magnetism is found and the temperature dependence of the penetration depth and superfluid density are obtained, proving the presence of two superconducting s -wave gaps.

Simultaneous X-ray and neutron diffraction Rietveld refinements of nanophase iron substituted hydroxyapatite

NASA Astrophysics Data System (ADS)

Kyriacou, Andreas

The effect of Fe substitution on the crystal structure of hydroxyapatite (HAp) is studied by applying simultaneous Rietveld refinements of powder x-ray and neutron diffraction patterns. Fe is one of the trace elements replacing Ca in HAp, which is the major mineral phase in bones and teeth. The morphology and magnetic properties of the Fe-HAp system are also studied by transmission electron microscopy and magnetization measurements. Samples of Ca(5-x)Fex(PO4)3OH with 0 ≤ x ≤ 0.3 were prepared. Single phase HAp was identified in x-ray diffraction patterns (XRD) of samples with x < 0.1 inferring that the solubility limits are less than 0.1. Hematite (alpha-Fe2O3) is identified as a secondary phase for higher Fe content. The refined parameters show that Fe is incorporated in the HAp structure by replacing Ca in the two crystallographic sites with a preference at the Ca2 site. This preference explains the small effect of the Fe substitution on the lattice constants of HAp. The overall decrease of the lattice constants is explained by the ionic size difference of Ca and Fe. The increasing trend of the a-lattice constant with x in the Fe substituted samples is attributed to a lattice relaxation caused by the substitution of the 4- and 6-fold Fe at the 7- and 9-fold Ca1 and Ca2 sites. This Ca local geometry reduction is indicated by a slight increase of the Ca1-O3 and Ca2-O1 bond lengths. Above the solubility limit x = 0.05, the Fe is partitioned in and out of the HAp structure with increasing nominal Fe content x. The excess Fe is oxidized to hematite. The TEM analysis and magnetic measurements support the results of the simultaneous Rietveld refinements. The TEM images show no significant effect on the morphology and size of the HAp particles upon Fe incorporation. The particles are either spheres or short rods of dimensions 20--60 nm. Hematite particles are imaged in the samples with x exceeding the solubility limit. These particles are spheres, about 15 nm in diameter and are more resistant to electron beam damage. Magnetic measurements reveal a transition of the diamagnetic pure HAp to paramagnetic Fe substituted HAp.

Identification of residues that control Li+ versus Na+ dependent Ca2+ exchange at the transport site of the mitochondrial NCLX.

PubMed

Roy, Soumitra; Dey, Kuntal; Hershfinkel, Michal; Ohana, Ehud; Sekler, Israel

2017-06-01

The Na + /Ca 2+ /Li + exchanger (NCLX) is a member of the Na + /Ca 2+ exchanger family. NCLX is unique in its capacity to transport both Na + and Li + , unlike other members, which are Na + selective. The major aim of this study was twofold, i.e., to identify NCLX residues that confer Li + or Na + selective Ca 2+ transport and map their putative location on NCLX cation transport site. We combined molecular modeling to map transport site of NCLX with euryarchaeal H + /Ca 2+ exchanger, CAX_Af, and fluorescence analysis to monitor Li + versus Na + dependent mitochondrial Ca 2+ efflux of transport site mutants of NCLX in permeabilized cells. Mutation of Asn149, Pro152, Asp153, Gly176, Asn467, Ser468, Gly494 and Asn498 partially or strongly abolished mitochondrial Ca 2+ exchange activity in intact cells. In permeabilized cells, N149A, P152A, D153A, N467Q, S468T and G494S demonstrated normal Li + /Ca 2+ exchange activity but a reduced Na + /Ca 2+ exchange activity. On the other hand, D471A showed dramatically reduced Li + /Ca 2+ exchange, but Na + /Ca 2+ exchange activity was unaffected. Finally, simultaneous mutation of four putative Ca 2+ binding residues was required to completely abolish both Na + /Ca 2+ and Li + /Ca 2+ exchange activities. We identified distinct Na + and Li + selective residues in the NCLX transport site. We propose that functional segregation in Li + and Na + sites reflects the functional properties of NCLX required for Ca 2+ exchange under the unique membrane potential and ion gradient across the inner mitochondrial membrane. The results of this study provide functional insights into the unique Li + and Na + selectivity of the mitochondrial exchanger. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech. Copyright © 2017 Elsevier B.V. All rights reserved.

Raman spectroscopic study of synthesized Na-bearing majoritic garnets

NASA Astrophysics Data System (ADS)

Okamoto, K.

2003-12-01

Majoritic garnets in diamond have been considered as the sample from mantle transition zone (e.g. Moore and Gurney, 1985). For non-destructive, in-situ Raman analysis, Gillet et al. (2002) systematically checked chemistry and Raman peak of various majoritic garnets in diamond. They treated majoritic component as number of excess-silica than 3.0 per formula unit. However, in the basaltic system, majorite garnets also have significant amounts of Na. Na substitution is coupled with Si and Ti as follows; Na +Ti = Ca +Al (Ringwood and Lovering, 1970), Na +Si = Ca + Al (Sobolev and Labrentav, 1971; Ringwood and Major, 1971) or Na + Si = Mg + Al (Gasparik, 1989). Each component in garnet is defined as follows; Mj (majorite) component = ((Si-3)-Na)/2), NaSi (Na2MSi5O12 where M= Ca, Mg, Fe2+) component = (Na-T)/2, and NaTi component = Ti/2. Okamoto and Maruyama (2003) conducted UHP experiments in the MORB + H2O system (KNCFMATSH) at 10-19 GPa. They show that 1) Mj and NaTi component are constant and lower than 0.1 at T = 900 \\deg C, and 2) NaSi component increases drastically above 15 GPa although it is neglibly small at P<15 GPa. Raman spectra was newly analyzed using Okamoto and Maruyama (2003)'s run charges. Above 15 GPa, there is a characteristic sharp peak at 910 cm-1 and broad shoulder between 800 and 900 cm-1 as well as broad band near 960 cm-1. Gillet et at (2002) concluded that the former peak at 910cm-1 is the only reliable signature for the majoritic garnet (Si>3). They also implied that the latter two broad peaks are diagnostic feature for Ti rich garnet (> 1wt% of TiO2) as well as peak at 1030 cm-1. However, in all P range (10-19 GPa) of the present study, TiO2 is higher than 1wt%, and there is a peak at 1030 cm-1. Additional Ti-free experiment at 16 GPa, 1200 \\deg C clearly revealed that Na-bearing majoritic garnet has a significant shoulder at 800-900 cm-1. Ref; Gasparik (1989) CMP, 102,389, Gillet et al. (2002) Am.Min., 87, 312, Moore and Gurney (1985)Nature, 318, 553, Okamoto and Maruyama (2003)PEPI, in press, Ringwood and Lovering (1970) EPSL, 7, 371, Ringwood and Major (1971)EPSL, 12, 411, Sobolev and Labrentav (1971)CMP, 31, 1.

IMF and [Na/Fe] abundance ratios from optical and NIR spectral features in early-type galaxies

NASA Astrophysics Data System (ADS)

La Barbera, F.; Vazdekis, A.; Ferreras, I.; Pasquali, A.; Allende Prieto, C.; Röck, B.; Aguado, D. S.; Peletier, R. F.

2017-01-01

We present a joint analysis of the four most prominent sodium-sensitive features (Na D, Na I λ8190Å, Na I λ1.14 μm, and Na I λ2.21 μm), in the optical and near-infrared spectral ranges, of two nearby, massive (σ ˜ 300 km s-1), early-type galaxies (named XSG1 and XSG2). Our analysis relies on deep Very Large Telescope/X-Shooter long-slit spectra, along with newly developed stellar population models, allowing for [Na/Fe] variations, up to ˜1.2 dex, over a wide range of age, total metallicity, and initial mass function (IMF) slope. The new models show that the response of the Na-dependent spectral indices to [Na/Fe] is stronger when the IMF is bottom heavier. For the first time, we are able to match all four Na features in the central regions of massive early-type galaxies finding an overabundance of [Na/Fe] in the range 0.5-0.7 dex and a bottom-heavy IMF. Therefore, individual abundance variations cannot be fully responsible for the trends of gravity-sensitive indices, strengthening the case towards a non-universal IMF. Given current limitations of theoretical atmosphere models, our [Na/Fe] estimates should be taken as upper limits. For XSG1, where line strengths are measured out to ˜0.8 Re, the radial trend of [Na/Fe] is similar to [α/Fe] and [C/Fe], being constant out to ˜0.5 Re, and decreasing by ˜0.2-0.3 dex at ˜0.8 Re, without any clear correlation with local metallicity. Such a result seems to be in contrast to the predicted increase of Na nucleosynthetic yields from asymptotic giant branch stars and Type II supernovae. For XSG1, the Na-inferred IMF radial profile is consistent, within the errors, with that derived from TiO features and the Wing-Ford band presented in a recent paper.

L-type Ca(2+) currents overlapping threshold Na(+) currents: could they be responsible for the "slip-mode" phenomenon in cardiac myocytes?

PubMed

Piacentino, Valentino; Gaughan, John P; Houser, Steven R

2002-03-08

Phosphorylation of Na channels has been suggested to increase their Ca permeability. Termed "slip-mode conductance" (SMC), this hypothesis predicts that Ca influx via protein kinase A (PKA)-modified Na channels can induce sarcoplasmic reticulum (SR) Ca release. We tested this hypothesis by determining if SR Ca release is graded with I(Na) in the presence of activated PKA (with Isoproterenol, ISO). V(m), I(m), and [Ca](i) were measured in feline (n=26) and failing human (n=19) ventricular myocytes. Voltage steps from -70 through -40 mV were used to grade I(Na). Na channel antagonists (tetrodotoxin), L-type Ca channel (I(Ca,L)) antagonists (nifedipine, cadmium, verapamil), and agonists (Bay K 8644, FPL 64176) were used to separate SMC from I(Ca,L). In the absence of ISO, I(Na) was associated with SR Ca release in human but not feline myocytes. After ISO, graded I(Na) was associated with small amounts of SR Ca release in feline myocytes and the magnitude of release increased in human myocytes. I(Na)-related SR Ca release was insensitive to tetrodotoxin (n=10) but was blocked by nifedipine (n=10) and cadmium (n=3). SR Ca release was induced over the same voltage range in the absence of ISO with Bay K 8644 and FPL 64176 (n=9). Positive voltage steps (to 0 mV) to fully activate Na channels (SMC) in the presence of ISO and Verapamil only caused SR Ca release when block of I(Ca,L) was incomplete. We conclude that PKA-mediated increases in I(Ca,L) and SR Ca loading can reproduce many of the experimental features of SMC.

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

Boberg, Owen M.; Friel, Eileen D.; Vesperini, Enrico

We present the Fe, Ca, Ti, Ni, Ba, Na, and O abundances for a sample of 53 red giant branch stars in the globular cluster (GC) NGC 5024 (M53). The abundances were measured from high signal-to-noise medium resolution spectra collected with the Hydra multi-object spectrograph on the Wisconsin–Indiana–Yale–NOAO 3.5 m telescope. M53 is of interest because previous studies based on the morphology of the cluster’s horizontal branch suggested that it might be composed primarily of first generation (FG) stars and differ from the majority of other GCs with multiple populations, which have been found to be dominated by the secondmore » generation (SG) stars. Our sample has an average [Fe/H] = −2.07 with a standard deviation of 0.07 dex. This value is consistent with previously published results. The alpha-element abundances in our sample are also consistent with the trends seen in Milky Way halo stars at similar metallicities, with enhanced [Ca/Fe] and [Ti/Fe] relative to solar. We find that the Na–O anti-correlation in M53 is not as extended as other GCs with similar masses and metallicities. The ratio of SG to the total number of stars in our sample is approximately 0.27 and the SG generation is more centrally concentrated. These findings further support that M53 might be a mostly FG cluster and could give further insight into how GCs formed the light element abundance patterns we observe in them today.« less

A newly developed Fe-doped calcium sulfide nanoparticles with magnetic property for cancer hyperthermia

NASA Astrophysics Data System (ADS)

Wu, Steven Yueh-Hsiu; Tseng, Ching-Li; Lin, Feng-Huei

2010-05-01

In this study, a magnetic iron-doped calcium sulfide (Fe-CaS) nanoparticle was newly developed and studied for the purpose of hyperthermia due to its promising magnetic property, adequate biodegradation rate, and relatively good biocompatibility. Fe-CaS nanoparticles were synthesized by a wet chemical co-precipitation process with heat treatment in a N2 atmosphere, and were subsequently cooled in N2 and exposed to air at a low temperature. The crystal structure of the Fe-CaS nanoparticles was similar to that of the CaS, which was identified by an X-ray diffractometer (XRD). The particle size was less than 40 nm based on a Debye-Scherrer equation and transmission electron microscope (TEM) examination. Magnetic properties obtained from the SQUID magnetometer demonstrated that the synthesized CaS was a diamagnetic property. Once the Fe ions were doped, the synthesized Fe-CaS converted into paramagnetism which showed no hysteresis loop. Having been heated above 600 °C in N2, the Fe-CaS showed a promising magnetic property to produce enough energy to increase the temperature for hyperthermia. 10 mg/ml of the Fe-CaS was able to generate heat to elevate the media temperature over 42.5 °C within 6 min. The area of the hysteresis loop increased with the increasing of the treated temperature, especially at 800 °C for 1 h. This is because more Fe ions replaced Ca ions in the lattice at the higher heat treatment temperature. The heat production was also increasing with the increasing of heat treatment temperature, which resulted in an adequate specific absorption ratio (SAR) value, which was found to be 45.47 W/g at 37 °C under an alternative magnetic field of f = 750 KHz , H = 10 Oe. The in vitro biocompatibility test of the synthesized Fe-CaS nanoparticles examined by the LDH assay showed no cytotoxicity to 3T3 fibroblast. The result of in vitro cell hyperthermia shows that under magnetic field the Fe-CaS nanoparticles were able to generate heat and kill the CT-26 cancer cells significantly. We believe that the developed Fe-CaS nanoparticles have great potential as thermo-seeds for cancer hyperthermia in the near future.

Early chemical enrichment of the Galactic dwarf satellites from a homogeneous and NLTE abundance analysis

NASA Astrophysics Data System (ADS)

Mashonkina, Lyudmila; Jablonka, Pascale; Sitnova, Tatyana; Pakhomov, Yuri; North, Pierre

2018-06-01

We review recent abundance results for very metal-poor (VMP, -4 ≤ [Fe/H] ≤ -2) stars in seven dwarf spheroidal galaxies (dSphs) and in the Milky Way (MW) halo comparison sample that were obtained based on high-resolution spectroscopic datasets, homogeneous and accurate atmospheric parameters, and the non-local thermodynamic equilibrium (NLTE) line formation for 10 chemical species. A remarkable gain of using such an approach is the reduction, compared to a simple compilation of the literature data, of the spread in abundance ratios at given metallicity within each galaxy and from one to the other. We show that all massive galaxies in our sample, that is, the MW halo and the classical dSphs Sculptor, Ursa Minor, Sextans, and Fornax, reveal a similar plateau at [α/Fe] \\simeq 0.3 for each of the α-process elements: Mg, Ca, and Ti. We put on a firm ground the evidence for a decline in α/Fe with increasing metallicity in the Boötes I ultra-faint dwarf galaxy (UFD), that is most probably due to the ejecta of type Ia supernovae. In our classical dSphs, we observe the dichotomy in the [Sr/Ba] versus [Ba/H] diagram, similarly to the MW halo, calling for two different nucleosynthesis channels for Sr at the earliest evolution stages of these galaxies. Our three UFDs, that is Boötes I, UMa II, and Leo IV, are depleted in Sr and Ba relative to Fe and Mg, with very similar ratios of [Sr/Mg] ≈ -1.3 and [Ba/Mg] ≈ -1 on the entire range of their Mg abundances. The subsolar Sr/Ba ratios of Boötes I and UMa II indicate a common r-process origin of their neutron-capture elements. For Na/Fe, Na/Mg, and Al/Mg, the MW halo and all dSphs reveal indistinguishable trends with metallicity, suggesting that the processes of Na and Al synthesis are identical in all systems, independent of their mass. Sculptor remains the classical dSph, in which the evidence for inhomogeneous mixing in the early evolution stage, at [Fe/H] < -2, is the strongest.

Calculation of Oxygen Fugacity in High Pressure Metal-Silicate Experiments and Comparison to Standard Approaches

NASA Technical Reports Server (NTRS)

Righter, K.; Ghiorso, M.

2009-01-01

Calculation of oxygen fugacity in high pressure and temperature experiments in metal-silicate systems is usually approximated by the ratio of Fe in the metal and FeO in the silicate melt: (Delta)IW=2*log(X(sub Fe)/X(sub FeO)), where IW is the iron-wustite reference oxygen buffer. Although this is a quick and easy calculation to make, it has been applied to a huge variety of metallic (Fe- Ni-S-C-O-Si systems) and silicate liquids (SiO2, Al2O3, TiO2, FeO, MgO, CaO, Na2O, K2O systems). This approach has surely led to values that have little meaning, yet are applied with great confidence, for example, to a terrestrial mantle at "IW-2". Although fO2 can be circumvented in some cases by consideration of Fe-M distribution coefficient, these do not eliminate the effects of alloy or silicate liquid compositional variation, or the specific chemical effects of S in the silicate liquid, for example. In order to address the issue of what the actual value of fO2 is in any given experiment, we have calculated fO2 from the equilibria 2Fe (metal) + SiO2 (liq) + O2 = Fe2SiO4 (liq).

Aqueous fluid composition in CI chondritic materials: Chemical equilibrium assessments in closed systems

NASA Astrophysics Data System (ADS)

Zolotov, Mikhail Yu.

2012-08-01

Solids of nearly solar composition have interacted with aqueous fluids on carbonaceous asteroids, icy moons, and trans-neptunian objects. These processes altered mineralogy of accreted materials together with compositions of aqueous and gaseous phases. We evaluated chemistry of aqueous solutions coexisted with CI-type chondritic solids through calculations of chemical equilibria in closed water-rock-gas systems at different compositions of initial fluids, water/rock mass ratios (0.1-1000), temperatures (<350 °C), and pressures (<2 kbars). The calculations show that fluid compositions are mainly affected by solubilities of solids, the speciation of chlorine in initial water-rock mixtures, and the occurrence of Na-bearing secondary minerals such as saponite. The major species in modeled alkaline solutions are Na+, Cl-, CO32-,HCO3-, K+, OH-, H2, and CO2. Aqueous species of Mg, Fe, Ca, Mn, Al, Ni, Cr, S, and P are not abundant in these fluids owing to low solubility of corresponding solids. Typical NaCl type alkaline fluids coexist with saponite-bearing mineralogy that usually present in aqueously altered chondrites. A common occurrence of these fluids is consistent with the composition of grains emitted from Enceladus. Na-rich fluids with abundant CO32-,HCO3-, and OH- anions coexist with secondary mineralogy depleted in Na. The Na2CO3 and NaHCO3 type fluids could form via accretion of cometary ices. NaOH type fluids form in reduced environments and may locally occur on parent bodies of CR carbonaceous chondrites. Supposed melting of accreted HCl-bearing ices leads to early acidic fluids enriched in Mg, Fe and other metals, consistent with signs of low-pH alteration in chondrites. Neutralization of these solutions leads to alkaline Na-rich fluids. Sulfate species have negligible concentrations in closed systems, which remain reduced, especially at elevated pressures created by forming H2 gas. Hydrogen, CO2, and H2O dominate in the gaseous phase, though the abundance of methane cannot be fairly estimated.

Spatial Heterogeneity of Stream Water Chemistry in the Elder Creek Catchment at the Eel River Critical Zone Observatory.

NASA Astrophysics Data System (ADS)

Thurnhoffer, B. M.; Lovill, S. M.; Nghiem, A.; Kim, H.; Bishop, J. K. B.

2014-12-01

How does stream chemistry vary with respect to discharge, flow distance, elevation, hill slope orientation, lithology, and vegetation on catchment scale? Is it possible to discern fast flowing seasonally recharged subsurface waters from long residence time waters contributing to base flow? To answer these questions, water samples were collected at ~80 locations distributed over the channel network of the (17 km2) Elder Creek catchment during surveys in May and August/September 2014. The site, located at the Angelo Coast Range Reserve near the headwaters of the South Fork of the Eel River in northern California, experiences a Mediterranean climate with warm dry summers and cold wet winters; this year (2014), our area has received less than 50% of expected precipitation and is experiencing an extreme drought. Our survey times correspond to the beginning of the dry season and late dry season, respectively. The subsurface lithology of the region almost uniform, being largely composed of argillite mudstone with intermittent areas underlain with sandstone. It is forested with Douglas fir, live and tan oaks, madrone and California bay laurel, which vary in abundance with hill-slope orientation. Due to drought, the Elder Catchment has recently experienced the effects of the nearby Lodge Lightening Complex Fire (first detection July 31 2014) and its effects may be differentiated through the continuous 1 - 3 day frequency sampling of Elder Creek water using the ISCO Gravity Filtration System (GFS; Kim et al. 2012, EST). All water samples are analyzed for dissolved major, minor, and trace solutes by Inductively Couple Plasma Mass Spectrometry and this report focuses on major solutes such as Na, K, Ca, Mg and Si; redox sensitive metals Fe and Mn; and Ba and Sr. Preliminary analysis of May 2014 data shows interesting patterns between tributaries, particularly differences between streams on north vs. south facing slopes. Concentrations of Ca, Mg, and Na decrease down slope in south facing tributaries, while they slightly increase downslope in north facing tributaries. Concentrations are relatively invariant in the Elder channel but Elder chemistry differs with respect to Na, Ca and Fe to the South Fork Eel River.

Protective effect of magnesium acetyltaurate against NMDA-induced retinal damage involves restoration of minerals and trace elements homeostasis.

PubMed

Jafri, Azliana Jusnida Ahmad; Arfuzir, Natasha Najwa Nor; Lambuk, Lidawani; Iezhitsa, Igor; Agarwal, Renu; Agarwal, Puneet; Razali, Norhafiza; Krasilnikova, Anna; Kharitonova, Maria; Demidov, Vasily; Serebryansky, Evgeny; Skalny, Anatoly; Spasov, Alexander; Yusof, Ahmad Pauzi Md; Ismail, Nafeeza Mohd

2017-01-01

Glutamate-mediated excitotoxicity involving N-methyl-d-aspartate (NMDA) receptors has been recognized as a final common outcome in pathological conditions involving death of retinal ganglion cells (RGCs). Overstimulation of NMDA receptors results in influx of calcium (Ca) and sodium (Na) ions and efflux of potassium (K). NMDA receptors are blocked by magnesium (Mg). Such changes due to NMDA overstimulation are also associated with not only the altered levels of minerals but also that of trace elements and redox status. Both the decreased and elevated levels of trace elements such as iron (Fe), zinc (Zn), copper (Cu) affect NMDA receptor excitability and redox status. Manganese (Mn), and selenium (Se) are also part of antioxidant defense mechanisms in retina. Additionally endogenous substances such as taurine also affect NMDA receptor activity and retinal redox status. Therefore, the aim of this study was to evaluate the effect of Mg acetyltaurate (MgAT) on the retinal mineral and trace element concentration, oxidative stress, retinal morphology and retinal cell apoptosis in rats after-NMDA exposure. One group of Sprague Dawley rats received intravitreal injection of vehicle while 4 other groups similarly received NMDA (160nmolL -1 ). Among the NMDA injected groups, 3 groups also received MgAT (320nmolL -1 ) as pre-treatment, co-treatment or post-treatment. Seven days after intravitreal injection, rats were sacrificed, eyes were enucleated and retinae were isolated for estimation of mineral (Ca, Na, K, Mg) and trace element (Mn, Cu, Fe, Se, Zn) concentration using Inductively Coupled Plasma (DRC ICP-MS) techniques (NexION 300D), retinal oxidative stress using Elisa, retinal morphology using H&E staining and retinal cell apoptosis using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Intravitreal NMDA injection resulted in increased concentration of Ca (4.6 times, p<0.0001), Mg (1.5 times, p<0.01), Na (3 times, p<0.0001) and K (2.3 times, p<0.0001) compared to vehicle injected group. This was accompanied with significant increase of Ca/Mg and Na/K ratios, 3 and 1.27 times respectively, compared to control group. The trace elements such as Cu, Fe and Zn also showed a significant increase amounting to 3.3 (p<0.001), 2.3 (p<0.0001) and 3 (p<0.0001) times respectively compared to control group. Se was increased by 60% (p<0.005). Pre-treatment with MgAT abolished effect of NMDA on minerals and trace elements more effectively than co- and post-treatment. Similar observations were made for retinal oxidative stress, retinal morphology and retinal cell apoptosis. In conclusion, current study demonstrated the protective effect of MgAT against NMDA-induced oxidative stress and retinal cell apoptosis. This effect of MgAT was associated with restoration of retinal concentrations of minerals and trace elements. Further studies are warranted to explore the precise molecular targets of MgAT. Nevertheless, MgAT seems a potential candidate in the management of diseases involving NMDA-induced excitotoxicity. Copyright © 2016 Elsevier GmbH. All rights reserved.

Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS - diurnal variations and PMF receptor modelling

NASA Astrophysics Data System (ADS)

Dall'Osto, M.; Querol, X.; Amato, F.; Karanasiou, A.; Lucarelli, F.; Nava, S.; Calzolai, G.; Chiari, M.

2013-04-01

Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb) were obtained by time (1 h) and size (PM2.5 particulate matter < 2.5 μm) resolved aerosol samples analysed by Particle Induced X-ray Emission (PIXE) measurements. In the Marie Curie European Union framework of SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), the approach used is the simultaneous sampling at two monitoring sites in Barcelona (Spain) during September-October 2010: an urban background site (UB) and a street canyon traffic road site (RS). Elements related to primary non-exhaust traffic emission (Fe, Cu), dust resuspension (Ca) and anthropogenic Cl were found enhanced at the RS, whereas industrial related trace metals (Zn, Pb, Mn) were found at higher concentrations at the more ventilated UB site. When receptor modelling was performed with positive matrix factorization (PMF), nine different aerosol sources were identified at both sites: three types of regional aerosols (regional sulphate (S) - 27%, biomass burning (K) - 5%, sea salt (Na-Mg) - 17%), three types of dust aerosols (soil dust (Al-Ti) - 17%, urban crustal dust (Ca) - 6%, and primary traffic non-exhaust brake dust (Fe-Cu) - 7%), and three types of industrial aerosol plumes-like events (shipping oil combustion (V-Ni) - 17%, industrial smelters (Zn-Mn) - 3%, and industrial combustion (Pb-Cl) - 5%, percentages presented are average source contributions to the total elemental mass measured). The validity of the PMF solution of the PIXE data is supported by very good correlations with external single particle mass spectrometry measurements. Some important conclusions can be drawn about the PM2.5 mass fraction simultaneously measured at the UB and RS sites: (1) the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2) by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3) a unique source of Pb-Cl (associated with combustion emissions) is found to be the major (82%) source of fine Cl in the urban agglomerate; (4) the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu) suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca) is found mainly resuspended by both traffic vortex and sea breeze; (5) urban dust (Ca) is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

The role of modifier cation field strength, oxygen speciation and network cation interaction in pressure-induced structural changes of silicate melts and glasses: 27Al, and 11B MAS NMR studies

NASA Astrophysics Data System (ADS)

Bista, S.; Stebbins, J. F.

2017-12-01

In aluminosilicate melts and glasses, both non-bridging oxygen content (NBO) and modifier cation field strength (Mg>Ca>Na>K) are known to facilitate network cation (e.g. Al, B) coordination increase with pressure. However, the role of these two compositional parameters in pressure-induced structural changes is derived from data for a limited set of compositions, where effects of the interaction between these parameters is less understood. For example, the effects of NBO are largely based on studies of Na and K aluminosilicate glasses, but effects of geologically important, higher field strength modifier cations such as Mg2+ and Fe2+ could well be significantly different. In this study, we look at a wide compositional range of Na, Ca and Mg aluminosilicate glasses (quenched from high pressure melts near to the glass transition temperature) to understand the roles of NBO and modifier cation field strength that can extend our view of processes important for silicate melts common in nature. Our results show that the role of NBO in pressure-induced structural changes varies systematically with increasing field strength of the modifier cation. In Na aluminosilicate glasses recovered from 1.5 to 3 GPa, large increases in average aluminum coordination are observed in glasses with high NBO content, while no detectable increases are seen for low nominal NBO (jadeite). In contrast, Mg aluminosilicate glasses with both high and low NBO show similar, large increases in average aluminum coordination with increasing pressure. The behaviors of Ca aluminosilicates fall between those of Na and Mg-rich glasses. We have also looked at interactions between different network forming cations in pressure-induced structural changes in low NBO Ca-aluminoborosilicate glasses with varying B/Si. Both aluminum and boron increase dramatically in coordination in these compositions 1.5 to 3 GPa. Increases in both average aluminum coordination and densification are larger in compositions containing higher boron concentrations, suggesting an interaction between boron and aluminum network cations in pressure-induced structural changes.

Detection of Labile Low-Molecular-Mass Transition Metal Complexes in Mitochondria

PubMed Central

McCormick, Sean P.; Moore, Michael J.; Lindahl, Paul A.

2015-01-01

Liquid chromatography was used with an on-line inductively coupled plasma mass spectrometer to detect low-molecular-mass (LMM) transition metal complexes in mitochondria isolated from fermenting yeast cells, human Jurkat cells, and mouse brain and liver. These complexes constituted 20 – 40% of total mitochondrial Mn, Fe, Zn, and Cu ions. The major LMM Mn complex in yeast mitochondria had a mass of ca. 1100 Da and a concentration of ~ 2 μM. Mammalian mitochondria contained a second Mn species with a mass of ca. 2000 Da at a comparable concentration. The major Fe complex in mitochondria isolated from exponentially growing yeast cells had a mass of ca. 580 Da; the concentration of Fe580 in mitochondria was ca. 100 μM. When mitochondria were isolated from fermenting cells in post-exponential phase, the mass of the dominant LMM Fe complex was ca. 1100 Da. Upon incubation, the intensity of Fe1100 declined and Fe580 increased, suggesting that the two are interrelated. Mammalian mitochondria contained Fe580 and 2 other Fe species (Fe2000 and Fe1100) at concentrations of ca. 50 μM each. The dominant LMM Zn species in mitochondria had a mass of ca. 1200 Da and a concentration of ca. 110 μM. Mammalian mitochondria contained a second major LMM Zn species at 1500 Da. The dominant LMM Cu species in yeast mitochondria had a mass of ca. 5000 Da and a concentration in yeast mitochondria of ca. 16 μM; Cu5000 was not observed in mammalian mitochondria. The dominant Co species in mitochondria, Co1200, had a concentration of 20 nM and was probably a cobalamin. Mammalian but not yeast mitochondria contained a LMM Mo species, Mo730, at ca. 1 μM concentration. Increasing Mn, Fe, Cu, and Zn concentrations 10 fold in the medium increased the concentration of the same element in the corresponding isolated mitochondria. Treatment with metal chelators confirmed that these LMM species were labile. The dominant S species at 1100 Da was not free GSH or GSSG. PMID:26018429

The Interface Structure of FeSe Thin Film on CaF2 Substrate and its Influence on the Superconducting Performance.

PubMed

Qiu, Wenbin; Ma, Zongqing; Patel, Dipak; Sang, Lina; Cai, Chuanbing; Shahriar Al Hossain, Mohammed; Cheng, Zhenxiang; Wang, Xiaolin; Dou, Shi Xue

2017-10-25

The investigations into the interfaces in iron selenide (FeSe) thin films on various substrates have manifested the great potential of showing high-temperature-superconductivity in this unique system. In present work, we obtain FeSe thin films with a series of thicknesses on calcium fluoride (CaF 2 ) (100) substrates and glean the detailed information from the FeSe/CaF 2 interface by using scanning transmission electron microscopy (STEM). Intriguingly, we have found the universal existence of a calcium selenide (CaSe) interlayer with a thickness of approximate 3 nm between FeSe and CaF 2 in all the samples, which is irrelevant to the thickness of FeSe layers. A slight Se deficiency occurs in the FeSe layer due to the formation of CaSe interlayer. This Se deficiency is generally negligible except for the case of the ultrathin FeSe film (8 nm in thickness), in which the stoichiometric deviation from FeSe is big enough to suppress the superconductivity. Meanwhile, in the overly thick FeSe layer (160 nm in thickness), vast precipitates are found and recognized as Fe-rich phases, which brings about degradation in superconductivity. Consequently, the thickness dependence of superconducting transition temperature (T c ) of FeSe thin films is investigated and one of our atmosphere-stable FeSe thin film (127 nm) possesses the highest T c onset /T c zero as 15.1 K/13.4 K on record to date in the class of FeSe thin film with practical thickness. Our results provide a new perspective for exploring the mechanism of superconductivity in FeSe thin film via high-resolution STEM. Moreover, approaches that might improve the quality of FeSe/CaF 2 interfaces are also proposed for further enhancing the superconducting performance in this system.

Close Association of Carbonic Anhydrase (CA2a and CA15a), Na+/H+ Exchanger (Nhe3b), and Ammonia Transporter Rhcg1 in Zebrafish Ionocytes Responsible for Na+ Uptake

PubMed Central

Ito, Yusuke; Kobayashi, Sayako; Nakamura, Nobuhiro; Miyagi, Hisako; Esaki, Masahiro; Hoshijima, Kazuyuki; Hirose, Shigehisa

2013-01-01

Freshwater (FW) fishes actively absorb salt from their environment to tolerate low salinities. We previously reported that vacuolar-type H+-ATPase/mitochondrion-rich cells (H-MRCs) on the skin epithelium of zebrafish larvae (Danio rerio) are primary sites for Na+ uptake. In this study, in an attempt to clarify the mechanism for the Na+ uptake, we performed a systematic analysis of gene expression patterns of zebrafish carbonic anhydrase (CA) isoforms and found that, of 12 CA isoforms, CA2a and CA15a are highly expressed in H-MRCs at larval stages. The ca2a and ca15a mRNA expression were salinity-dependent; they were upregulated in 0.03 mM Na+ water whereas ca15a but not ca2a was down-regulated in 70 mM Na+ water. Immunohistochemistry demonstrated cytoplasmic distribution of CA2a and apical membrane localization of CA15a. Furthermore, cell surface immunofluorescence staining revealed external surface localization of CA15a. Depletion of either CA2a or CA15a expression by Morpholino antisense oligonucleotides resulted in a significant decrease in Na+ accumulation in H-MRCs. An in situ proximity ligation assay demonstrated a very close association of CA2a, CA15a, Na+/H+ exchanger 3b (Nhe3b), and Rhcg1 ammonia transporter in H-MRC. Our findings suggest that CA2a, CA15a, and Rhcg1 play a key role in Na+uptake under FW conditions by forming a transport metabolon with Nhe3b. PMID:23565095

Calcium triggers reversal of calmodulin on nested anti-parallel sites in the IQ motif of the neuronal voltage-dependent sodium channel NaV1.2.

PubMed

Hovey, Liam; Fowler, C Andrew; Mahling, Ryan; Lin, Zesen; Miller, Mark Stephen; Marx, Dagan C; Yoder, Jesse B; Kim, Elaine H; Tefft, Kristin M; Waite, Brett C; Feldkamp, Michael D; Yu, Liping; Shea, Madeline A

2017-05-01

Several members of the voltage-gated sodium channel family are regulated by calmodulin (CaM) and ionic calcium. The neuronal voltage-gated sodium channel Na V 1.2 contains binding sites for both apo (calcium-depleted) and calcium-saturated CaM. We have determined equilibrium dissociation constants for rat Na V 1.2 IQ motif [IQRAYRRYLLK] binding to apo CaM (~3nM) and (Ca 2+ ) 4 -CaM (~85nM), showing that apo CaM binding is favored by 30-fold. For both apo and (Ca 2+ ) 4 -CaM, NMR demonstrated that Na V 1.2 IQ motif peptide (Na V 1.2 IQp ) exclusively made contacts with C-domain residues of CaM (CaM C ). To understand how calcium triggers conformational change at the CaM-IQ interface, we determined a solution structure (2M5E.pdb) of (Ca 2+ ) 2 -CaM C bound to Na V 1.2 IQp . The polarity of (Ca 2+ ) 2 -CaM C relative to the IQ motif was opposite to that seen in apo CaM C -Na v 1.2 IQp (2KXW), revealing that CaM C recognizes nested, anti-parallel sites in Na v 1.2 IQp . Reversal of CaM may require transient release from the IQ motif during calcium binding, and facilitate a re-orientation of CaM N allowing interactions with non-IQ Na V 1.2 residues or auxiliary regulatory proteins interacting in the vicinity of the IQ motif. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of Na-Ca exchange current in the cardiac action potential.

PubMed

Janvier, N C; Boyett, M R

1996-07-01

Since 1981, when Mullins published his provocative book proposing that the Na-Ca exchanger is electrogenic, it has been shown, first by computer simulation by Noble and later by experiment by various investigators, that inward iNaCa triggered by the Ca2+ transient is responsible for the low plateau of the atrial action potential and contributes to the high plateau of the ventricular action potential. Reduction or complete block of inward iNaCa by buffering intracellular Ca2+ with EGTA or BAPTA, by blocking SR Ca2+ release or by substituting extracellular Na+ with Li+ can result in a shortening of the action potential. The effect of block of outward iNaCa or complete block of both inward and outward iNaCa on the action potential has not been investigated experimentally, because of the lack of a suitable blocker, and remains a goal for the future. An increase in the intracellular Na+ concentration (after the application of cardiac glycoside or an increase in heart rate) or an increase in extracellular Ca2+ are believed to lead to an outward shift in iNaCa at plateau potentials and a shortening of the action potential. Changes in the Ca2+ transient are expected to result in changes in inward iNaCa and thus the action potential. This may explain the shortening of the premature action potential as well as the prolongation of the action potential when a muscle is allowed to shorten during the action potential. Inward iNaCa may play an important role in both normal and abnormal pacemaker activity in the heart.

Contents and composition of organic matter in subsurface soils affected by land use and soil mineralogy

NASA Astrophysics Data System (ADS)

Ellerbrock, Ruth H.; Kaiser, Michael

2010-05-01

Land use and mineralogy affect the ability of surface as well as subsurface soils to sequester organic carbon and their contribution to mitigate the greenhouse effect. This study aimed to investigate the long-term impact of land use (i.e., arable and forest) and soil mineralogy on contents and composition of soil organic matter (SOM) from subsurface soils. Seven soils different in mineralogy (Albic and Haplic Luvisol, Colluvic and Haplic Regosol, Haplic and Vertic Cambisol, Haplic Stagnosol) were selected within Germany. Soil samples were taken from forest and adjacent arable sites. First, particulate and water soluble organic matter were separated from the subsurface soil samples. From the remaining solid residues the OM(PY) fractions were separated, analyzed for its OC content (OCPY) and characterized by FTIR spectroscopy. For the arable subsurface soils multiple regression analyses indicate significant positive relationships between the soil organic carbon contents and the contents of i) exchangeable Ca and oxalate soluble Fe, and Alox contents. Further for the neutral arable subsurface soils the contents OCPY weighted by its C=O contents were found to be related to the contents of Ca indicating interactions between OM(PY) and Ca cations. For the forest subsurface soils (pH <5) the OCPY contents were positively related with the contents of Na-pyrophosphate soluble Fe and Al. For the acidic forest subsurface soils such findings indicate interactions between OM(PY) and Fe3+ and Al3+ cations. The effects of land use and soil mineralogy on contents and composition of SOM and OM(PY) will be discussed.

Development of a SREX Flowsheet for the Separation of Strontium from Dissolved INEEL Zirconium Calcine

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

Law, Jack Douglas; Wood, David James; Todd, Terry Allen

1999-02-01

Laboratory experimentation has indicated that the SREX process is effective for partitioning 90 Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run #64 pilot plant calcine spiked with 85 Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4',4'(5')-di-(tert-butylcyclohexo)-18-crown-6 andmore » 1.5 M TBP in Isopar-L.), a 1.0 M NaNO3 scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO3 strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO3 wash section to remove degradation products from the solvent, and a 0.1 M HNO3 rinse section. The behavior of 85 Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted 85 Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for 85 Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO3 resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO3 scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable.« less

Development of a SREX flowsheet for the separation of strontium from dissolved INEEL zirconium calcine

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

Law, J.D.; Wood, D.J.; Todd, T.A.

1999-01-01

Laboratory experimentation has indicated that the SREX process is effective for partitioning {sup 90}Sr from acidic radioactive waste solutions located at the Idaho Nuclear Technology and Engineering Center. These laboratory results were used to develop a flowsheet for countercurrent testing of the SREX process with dissolved pilot plant calcine. Testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. Dissolved Run No.64 pilot plant calcine spiked with {sup 85}Sr was used as feed solution for the testing. The flowsheet tested consisted of an extraction section (0.15 M 4{prime},4{prime}(5{prime})-di-(tert-butylcyclohexo)-18-crown-6 andmore » 1.5 M TBP in Isopar-L.), a 1.0 M NaNO{sub 3} scrub section to remove extracted K from the SREX solvent, a 0.01 M HNO{sub 3} strip section for the removal of Sr from the SREX solvent, a 0.25 M Na2CO{sub 3} wash section to remove degradation products from the solvent, and a 0.1 M HNO{sub 3} rinse section. The behavior of {sup 85}Sr, Na, K, Al, B, Ca, Cr, Fe, Ni, and Zr was evaluated. The described flowsheet successfully extracted {sup 85}Sr from the dissolved pilot plant calcine with a removal efficiency of 99.6%. Distribution coefficients for {sup 85}Sr ranged from 3.6 to 4.5 in the extraction section. With these distribution coefficients a removal efficiency of approximately >99.99% was expected. It was determined that the lower than expected removal efficiency can be attributed to a stage efficiency of only 60% in the extraction section. Extracted K was effectively scrubbed from the SREX solvent with the 1.0 M NaNO{sub 3} resulting in only 6.4% of the K in the HLW strip product. Sodium was not extracted from the dissolved calcine by the SREX solvent; however, the use of a 1.0 M NaNO{sub 3} scrub solution resulted in a Na concentration of 70 mg/L (12.3% of the feed concentration) in the HLW strip product. Al, B, Ca, Cr, Fe, Ni, and Zr were determined to be essentially inextractable.« less

Immobilization of uranium and arsenic by injectible iron and hydrogen stimulated autotrophic sulphate reduction

NASA Astrophysics Data System (ADS)

Burghardt, D.; Simon, E.; Knöller, K.; Kassahun, A.

2007-12-01

The main object of the study was the development of a long-term efficient and inexpensive in-situ immobilization technology for uranium (U) and arsenic (As) in smaller and decentralized groundwater discharges from abandoned mining processing sites. Therefore, corrosion of grey cast iron (gcFe) and nano-scale iron particles (naFe) as well as hydrogen stimulated autotrophic sulphate reduction (aSR) were investigated. Two column experiments with sulphate reducing bacterias (SRB) (biotic gcFe , biotic naFe) and one abiotic gcFe-column experiment were performed. In the biotic naFe column, no particle translocation was observed and a temporary but intensive naFe corrosion indicated by a decrease in Eh, a pH increase and H 2 evolution. Decreasing sulphate concentrations and 34S enrichment in the column effluent indicated aSR. Fe(II) retention could be explained by siderite and consequently FeS precipitation by geochemical modeling (PhreeqC). U and As were completely immobilised within the biotic naFe column. In the biotic gcFe column, particle entrapment in open pore spaces resulted in a heterogeneous distribution of Fe-enriched zones and an increase in permeability due to preferential flow. However, Fe(II) concentrations in the effluent indicated a constant and lasting gcFe corrosion. An efficient immobilization was found for As, but not for U.

Micronutrient intake in advanced age: Te Puāwaitanga o Ngā Tapuwae Kia ora Tonu, Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ).

PubMed

Wham, Carol; Teh, Ruth; Moyes, Simon A; Rolleston, Anna; Muru-Lanning, Marama; Hayman, Karen; Kerse, Ngaire; Adamson, Ashley

2016-11-09

A high prevalence of undernutrition has previously been reported in indigenous Māori (49 %) and non-Māori (38 %) octogenarians and may be associated with risk of micronutrient deficiencies. We examined vitamin and mineral intakes and the contributing food sources among 216 Māori and 362 non-Māori participating in Life and Living to Advanced age a Cohort Study in New Zealand, using a repeat 24-h multiple-pass recall. More than half of the Māori and non-Māori participants had intakes below the estimated average requirement from food alone for Ca, Mg and Se. Vitamin B6 (Māori women only), folate (women only), vitamin E (Māori women; all men) and Zn (men only) were low in these ethnic and sex subgroups. Women had intakes of higher nutrient density in folate, vitamin C, Ca, Mg, K, vitamin A (non-Māori) and β-carotene (Māori) compared with men (P<0·05). When controlling for age and physical function, β-carotene, folate, vitamin C, Ca and Mg were no longer significantly different, but vitamins B2, B12, E and D, Fe, Na, Se and Zn became significantly different for Māori between men and women. When controlling for age and physical function, vitamins A and C and Ca were no longer significantly different, but vitamin B2, Fe, Na and Zn became significantly different for non-Māori between men and women. For those who took nutritional supplements, Māori were less likely to be deficient in food alone intake of vitamin A, folate and Mg, whereas non-Maori were less likely to be deficient in intakes of Mg, K and Zn, but more likely to be deficient in vitamin B12 intake. A lack of harmonisation in nutrient recommendations hinders the interpretation of nutrient adequacy; nonetheless, Ca, Mg and Se are key micronutrients of concern. Milk and cheese were important contributions to Ca intake, whereas bread was a key source of Mg and Se. Examination of dietary intake related to biochemical status and health outcomes will establish the utility of these observations.

Spatial Associations and Chemical Composition of Organic Carbon Sequestered in Fe, Ca, and Organic Carbon Ternary Systems.

PubMed

Sowers, Tyler D; Adhikari, Dinesh; Wang, Jian; Yang, Yu; Sparks, Donald L

2018-05-25

Organo-mineral associations of organic carbon (OC) with iron (Fe) oxides play a major role in environmental OC sequestration, a process crucial to mitigating climate change. Calcium has been found to have high coassociation with OC in soils containing high Fe content, increase OC sorption extent to poorly crystalline Fe oxides, and has long been suspected to form bridging complexes with Fe and OC. Due to the growing realization that Ca may be an important component of C cycling, we launched a scanning transmission X-ray microscopy (STXM) investigation, paired with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, in order to spatially resolve Fe, Ca, and OC relationships and probe the effect of Ca on sorbed OC speciation. We performed STXM-NEXAFS analysis on 2-line ferrihydrite reacted with leaf litter-extractable dissolved OC and citric acid in the absence and presence of Ca. Organic carbon was found to highly associate with Ca ( R 2 = 0.91). Carboxylic acid moieties were dominantly sequestered; however, Ca facilitated the additional sequestration of aromatic and phenolic moieties. Also, C NEXAFS revealed polyvalent metal ion complexation. Our results provide evidence for the presence of Fe-Ca-OC ternary complexation, which has the potential to significantly impact how organo-mineral associations are modeled.

Formation of unusual Cr5+ charge state in CaCr0.5Fe0.5O3 perovskite

NASA Astrophysics Data System (ADS)

Dai, Jian-Hong; Zhao, Qing; Sun, Qian; Zhang, Shuo; Wang, Xiao; Shen, Xu-Dong; Liu, Zhe-Hong; Shen, Xi; Yu, Ri-Cheng; Chan, Ting-Shan; Li, Lun-Xiong; Zhou, Guang-Hui; Yang, Yi-feng; Jin, Chang-Qing; Long, You-Wen

2018-03-01

A new oxide CaCr0.5Fe0.5O3 was prepared under high pressure and temperature conditions. It crystallizes in a B-site disordered Pbnm perovskite structure. The charge combination is determined to be Cr5+/Fe3+ with the presence of unusual Cr5+ state in octahedral coordination, although Cr4+ and Fe4+ occur in the related perovskites CaCrO3 and CaFeO3. The randomly distributed Cr5+ and Fe3+ spins lead to short-range ferromagnetic coupling, whereas an antiferromagnetic phase transition takes place near 50 K due to the Fe3+–O–Fe3+ interaction. In spite of the B-site Cr5+/Fe3+ disorder, the compound exhibits electrical insulating behavior. First-principles calculations further demonstrate the formation of {CaCr}}0.55+{Fe}}0.53+{{{O}}}3 charge combination, and the electron correlation effect of Fe3+ plays an important role for the insulting ground state. CaCr0.5Fe0.5O3 provides the first Cr5+ perovskite system with octahedral coordination, opening a new avenue to explore novel transition-metal oxides with exotic charge states. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574378, 51772324, and 61404052),the National Basic Research Program of China (Grant No. 2014CB921500), and the Chinese Academy of Sciences (Grant Nos. YZ201555, QYZDB-SSW-SLH013, GJHZ1773, and XDB07030300).

Phase relations in the system diopside-jadeite at high pressures and high temperatures

NASA Astrophysics Data System (ADS)

Liu, Lin-Gun

1980-05-01

Phase behaviour in the system diopside-jadeite (CaMgSi 2O 6sbnd NaAlSi 2O 6) have been investigated in the pressure region 100-300 kbar at about 1000°C in a diamond-anvil press coupled with laser heating. The omphacite solid solution extends from 30 to at least 200 kbar for the entire system. Omphacites, ranging in composition from pure diopside to more than 40 mole % jadeite, transform to diopside (II) at pressures greater than 230 kbar. Diopside (II), which probably possesses a perovskite-type structure, cannot be preserved when experiments are quenched to ambient conditions. Jadeite-rich omphacites were found to decompose into an assemblage of NaAlSiO 4(CaFe 2O 4-type structure) + stishovite + diopside (II) (?) at pressures greater than about 260 kbar. These results suggest that an eclogitic model mantle would not display the 400-km seismic discontinuity. Moreover, sodium in the transition zone and lower mantle would most likely be accommodated in phases of omphacite and diopside (II).

Inorganic Macro- and Micronutrients in “Superberries” Black Chokeberries (Aronia melanocarpa) and Related Teas

PubMed Central

Juranović Cindrić, Iva; Zeiner, Michaela; Mihajlov-Konanov, Darija; Stingeder, Gerhard

2017-01-01

Black chokeberries (Aronia melanocarpa) are considered to be functional food containing high amounts of anthocyanins, phenols, antioxidants, vitamins and minerals. Whereas organic compounds are well studied, there is little research on the mineral composition of the chokeberries. Thus, the presented study is focused on the determination of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Se, Sr and Zn in black chokeberry fruits and infusions to study the metals’ extractability. The nutrients Ca, K and Mg are present in the fruits (dried matter) at g/kg level, whereas the other elements are present from µg/kg up to mg/kg level. The extraction yields of the metals from the infusion range from 4 (Al, Mn) up to 44% (Na). The toxic elements present do not pose any health risk when berries or infusions are consumed. Concluding, Aronia berries, as well as infusions derived from them, are a good dietary source of essential metals in addition to the organic compounds also contained. PMID:28524107

Na/Ca exchange in the basolateral membrane of the A6 cell monolayer: role in Cai homeostasis.

PubMed

Brochiero, E; Raschi, C; Ehrenfeld, J

1995-05-01

The presence of a Na/Ca exchanger in A6 cells was investigated by measuring intracellular calcium (Cai) fluctuations and the 45Ca fluxes through the basolateral membranes (blm) of the cell monolayer. Removal of Na+ from the medium produced a transient increase in Cai followed by a regulatory phase returning Cai to control levels in 3-4 min, this phase being greatly accelerated (< 60 s) by NaCl addition (apparent Km of approximately 5 mM Na+). The Cai increase was only found with the Na(+)-free medium on the basolateral side of the cell monolayer. A twofold increase in the 45Ca influx was observed under these conditions. In Ca(2+)- depleted cells, the initial Cai increase after Ca2+ addition to the medium was greater when the putative Na/Ca exchanger was not functioning (i.e. in a Na(+)-free medium). 45Ca effluxes through the blm of the monolayer were greatly and transiently increased by a Na(+)-free medium on the serosal side and blocked by orthovanadate (1 mM). The Cai increased induced by a hypo-osmotic shock was greater in cells bathed in a Na(+)-medium, conditions expected to block the activity of the Na/Ca exchanger. These findings support the hypothesis that a Na/Ca exchanger is present on the blm of A6 cells and affirm its role in Cai homeostasis in steady-state conditions and following osmotic shock. In addition, a Ca2+ pump also located on the blm and Ca2+ stores sensitive to inositol 1,4,5-trisphosphate were found to be implicated in Cai homeostasis.

Batteries: An Advanced Na-FeCl2 ZEBRA Battery for Stationary Energy Storage Application

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

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong

2015-06-17

Sodium-metal chloride batteries, ZEBRA, are considered as one of the most important electrochemical devices for stationary energy storage applications because of its advantages of good cycle life, safety, and reliability. However, sodium-nickel chloride (Na-NiCl2) batteries, the most promising redox chemistry in ZEBRA batteries, still face great challenges for the practical application due to its inevitable feature of using Ni cathode (high materials cost). In this work, a novel intermediate-temperature sodium-iron chloride (Na-FeCl2) battery using a molten sodium anode and Fe cathode is proposed and demonstrated. The first use of unique sulfur-based additives in Fe cathode enables Na-FeCl2 batteries can bemore » assembled in the discharged state and operated at intermediate-temperature (<200°C). The results in this work demonstrate that intermediate-temperature Na-FeCl2 battery technology could be a propitious solution for ZEBRA battery technologies by replacing the traditional Na-NiCl2 chemistry.« less

A Cytoplasmic New Catalytic Subunit of Calcineurin in Trypanosoma cruzi and Its Molecular and Functional Characterization

PubMed Central

Orrego, Patricio R.; Olivares, Héctor; Cordero, Esteban M.; Bressan, Albert; Cortez, Mauro; Sagua, Hernán; Neira, Ivan; González, Jorge; da Silveira, José Franco; Yoshida, Nobuko; Araya, Jorge E.

2014-01-01

Parasitological cure for Chagas disease is considered extremely difficult to achieve because of the lack of effective chemotherapeutic agents against Trypanosoma cruzi at different stages of infection. There are currently only two drugs available. These have several limitations and can produce serious side effects. Thus, new chemotherapeutic targets are much sought after. Among T. cruzi components involved in key processes such as parasite proliferation and host cell invasion, Ca2+-dependent molecules play an important role. Calcineurin (CaN) is one such molecule. In this study, we cloned a new isoform of the gene coding for CL strain catalytic subunit CaNA (TcCaNA2) and characterized it molecularly and functionally. There is one copy of the TcCaNA2 gene per haploid genome. It is constitutively transcribed in all T. cruzi developmental forms and is localized predominantly in the cytosol. In the parasite, TcCaNA2 is associated with CaNB. The recombinant protein TcCaNA2 has phosphatase activity that is enhanced by Mn2+/Ni2+. The participation of TcCaNA2 in target cell invasion by metacyclic trypomastigotes was also demonstrated. Metacyclic forms with reduced TcCaNA2 expression following treatment with morpholino antisense oligonucleotides targeted to TcCaNA2 invaded HeLa cells at a lower rate than control parasites treated with morpholino sense oligonucleotides. Similarly, the decreased expression of TcCaNA2 following treatment with antisense morpholino oligonucleotides partially affected the replication of epimastigotes, although to a lesser extent than the decrease in expression following treatment with calcineurin inhibitors. Our findings suggest that the calcineurin activities of TcCaNA2/CaNB and TcCaNA/CaNB, which have distinct cellular localizations (the cytoplasm and the nucleus, respectively), may play a critical role at different stages of T. cruzi development, the former in host cell invasion and the latter in parasite multiplication. PMID:24498455

Backbone resonance assignments of complexes of human voltage-dependent sodium channel NaV1.2 IQ motif peptide bound to apo calmodulin and to the C-domain fragment of apo calmodulin.

PubMed

Mahling, Ryan; Kilpatrick, Adina M; Shea, Madeline A

2017-10-01

Human voltage-gated sodium channel Na V 1.2 has a single pore-forming α-subunit and two transmembrane β-subunits. Expressed primarily in the brain, Na V 1.2 is critical for initiation and propagation of action potentials. Milliseconds after the pore opens, sodium influx is terminated by inactivation processes mediated by regulatory proteins including calmodulin (CaM). Both calcium-free (apo) CaM and calcium-saturated CaM bind tightly to an IQ motif in the C-terminal tail of the α-subunit. Our thermodynamic studies and solution structure (2KXW) of a C-domain fragment of apo 13 C, 15 N- CaM (CaM C ) bound to an unlabeled peptide with the sequence of rat Na V 1.2 IQ motif showed that apo CaM C (a) was necessary and sufficient for binding, and (b) bound more favorably than calcium-saturated CaM C . However, we could not monitor the Na V 1.2 residues directly, and no structure of full-length CaM (including the N-domain of CaM (CaM N )) was determined. To distinguish contributions of CaM N and CaM C , we used solution NMR spectroscopy to assign the backbone resonances of a complex containing a 13 C, 15 N-labeled peptide with the sequence of human Na V 1.2 IQ motif (Na V 1.2 IQp ) bound to apo 13 C, 15 N-CaM or apo 13 C, 15 N-CaM C . Comparing the assignments of apo CaM in complex with Na V 1.2 IQp to those of free apo CaM showed that residues within CaM C were significantly perturbed, while residues within CaM N were essentially unchanged. The chemical shifts of residues in Na V 1.2 IQp and in the C-domain of CaM were nearly identical regardless of whether CaM N was covalently linked to CaM C . This suggests that CaM N does not influence apo CaM binding to Na V 1.2 IQp .

Iron deposition as acidic groundwater encounters carbonates in the alluvium of Pinal Creek, Arizona, U.S.A.

USGS Publications Warehouse

Lind, Carol J.; Oscarson, R.L.

1997-01-01

In a column experiment, acidic groundwater from Pinal Creek Arizona, a Cu mining area, was eluted through a composited alluvial sample obtained from a core that had been removed from a well downgradient of the acidic groundwater. The minerals present in typical grains and flakes in the alluvium before and after the elution were determined by X-ray diffraction (XRD), scanning electron microscopy, and energy dispersive multichannel analyses (EDX). The concentrations of Fe, Ti, Mn, Si, Al, Na, Ca, K, Mg and S in these grains and flakes and in their microcrystalline surface coatings were measured by EDX. In addition to magnetite, hematite, and Fe-Ti oxides, Fe was most concentrated in micas (especially biotite-like flakes) and in the microcrystalline coatings. The measured elements in these microcrystalline coatings were primarily K, Fe, Al, and Si. The microcrystalline coatings on the mica flakes also contained Mg. The approximate 1:3 Mg:Si atomic ratios (ARs) of the biotite-like flakes both before and after the elution would suggest that the Fe deposited during the elution had not substituted for Mg in these flakes. As a result of the elution, assuming no loss of Si, the averaged recorded Fe:Si AR of the microcrystalline coatings increased from (0,46 to 0.58):3.00. Iron deposition on the typical grains and flakes may relate to the presence of Fe in the particle on which it is deposited or to the presence of Fe in the microcrystalline surface coatings before elution. The data here are not sufficient for a statistical evaluation, but elution caused the following trends: (1) The Fe:Si A R increased in the (K,Fe,Al,Si)-microcrystalline surface coatings; (2) For the mica flakes, there was more than a 2-fold increase in the Fe:Si AR for the microcrystalline surface coatings of the Fe-rich biotite-like flakes but no measurable increase of the Fe:Si AR for the microcrystalline surface coatings of the muscovite-like flakes that contained 3-5 times less Fe; (3) Also for the biotite-like flakes, the increase in Fe:Si AR was greater in the flakes that had a higher Fe:Si AR; (4) The Fe deposition on the Fe-rich microcrystalline surface coatings of the feldspar was much greater than on the Fe-poor, beige quartz and feldspar grains that, prior to elution, had only CaSO4 microcrystalline coatings; and (5) No Fe was deposited on Fe-poor grains with no microcrystalline surface coating.

CO2 sensing of La0.875Ca0.125FeO3 in wet vapor: a comparison of experimental results and first-principles calculations.

PubMed

Wang, Xiaofeng; Chen, Yanping; Qin, Hongwei; Li, Ling; Shi, Changmin; Liu, Liang; Hu, Jifan

2015-05-28

Experimental results show that with an increase of relative humidity, the resistance of La0.875Ca0.125FeO3 decreases at room temperature but increases at higher temperatures (140-360 °C). The humid effect at room temperature is due to the movement of H(+) or H3O(+) inside of the condensed water layer on the surface of La0.875Ca0.125FeO3. Regarding the humid effect at high temperatures, the density functional theory (DFT) calculations show that H2O can be adsorbed onto the La0.875Ca0.125FeO3 surface in the molecular and dissociative adsorption configurations, where the La0.875Ca0.125FeO3 surface gains some electrons from H2O or its dissociative products, consistent with our observation. Experimental results also show that CO2 sensing response at high temperatures decreases with an increase of room-temperature relative humidity. DFT calculations indicate that CO2 adsorbed onto the La0.875Ca0.125FeO3(010) surface, where high concentration oxygen adsorption occurs without water adsorption nearby, releases some electrons into the semiconductor surface, playing the role of a donor. The interaction between CO2 and the local La0.875Ca0.125FeO3(010) surface with pre-adsorption of H2O nearby results in some electron transfer from the La0.875Ca0.125FeO3 surface to CO2, which is responsible for the weakening of CO2 response at high temperatures for La0.875Ca0.125FeO3 with an increase of room-temperature relative humidity.

Magnetic solid base catalyst CaO/CoFe2O4 for biodiesel production: Influence of basicity and wettability of the catalyst in catalytic performance

NASA Astrophysics Data System (ADS)

Zhang, Pingbo; Han, Qiuju; Fan, Mingming; Jiang, Pingping

2014-10-01

A novel magnetic solid base catalyst CaO/CoFe2O4 was successfully prepared with CoFe2O4 synthesized by hydrothermal method as the magnetic core and applied to the transesterification of soybean oil for the production of biodiesel. The magnetic solid base catalysts were characterized by a series of techniques including CO2-TPD, powder XRD, TGA, TEM and the contact angle measurement of the water droplet. It was demonstrated that CaO/CoFe2O4 has stronger magnetic strength indicating perfect utility for repeated use and better basic strength. Compared with CaO/ZnFe2O4 and CaO/MnFe2O4, solid base catalyst CaO/CoFe2O4 has better catalytic performance, weaker hydroscopicity and stronger wettability, demonstrating that catalytic performance was relative to both basicity of catalyst and the full contact between the catalyst and the reactants, but the latter was a main factor in the catalytic system.

Crosslink between calcium and sodium signalling.

PubMed

Verkhratsky, Alexei; Trebak, Mohamed; Perocchi, Fabiana; Khananshvili, Daniel; Sekler, Israel

2018-02-01

What is the topic of this review? This paper overviews the links between Ca 2+ and Na + signalling in various types of cells. What advances does it highlight? This paper highlights the general importance of ionic signalling and overviews the molecular mechanisms linking Na + and Ca 2+ dynamics. In particular, the narrative focuses on the molecular physiology of plasmalemmal and mitochondrial Na + -Ca 2+ exchangers and plasmalemmal transient receptor potential channels. Functional consequences of Ca 2+ and Na + signalling for co-ordination of neuronal activity with astroglial homeostatic pathways fundamental for synaptic transmission are discussed. Transmembrane ionic gradients, which are an indispensable feature of life, are used for generation of cytosolic ionic signals that regulate a host of cellular functions. Intracellular signalling mediated by Ca 2+ and Na + is tightly linked through several molecular pathways that generate Ca 2+ and Na + fluxes and are in turn regulated by both ions. Transient receptor potential (TRP) channels bridge endoplasmic reticulum Ca 2+ release with generation of Na + and Ca 2+ currents. The plasmalemmal Na + -Ca 2+ exchanger (NCX) flickers between forward and reverse mode to co-ordinate the influx and efflux of both ions with membrane polarization and cytosolic ion concentrations. The mitochondrial calcium uniporter channel (MCU) and mitochondrial Na + -Ca 2+ exchanger (NCLX) mediate Ca 2+ entry into and release from this organelle and couple cytosolic Ca 2+ and Na + fluctuations with cellular energetics. Cellular Ca 2+ and Na + signalling controls numerous functional responses and, in the CNS, provides for fast regulation of astroglial homeostatic cascades that are crucial for maintenance of synaptic transmission. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Fe²⁺ block and permeation of CaV3.1 (α1G) T-type calcium channels: candidate mechanism for non-transferrin-mediated Fe²⁺ influx.

PubMed

Lopin, Kyle V; Gray, I Patrick; Obejero-Paz, Carlos A; Thévenod, Frank; Jones, Stephen W

2012-12-01

Iron is a biologically essential metal, but excess iron can cause damage to the cardiovascular and nervous systems. We examined the effects of extracellular Fe²⁺ on permeation and gating of Ca(V)3.1 channels stably transfected in HEK293 cells, by using whole-cell recording. Precautions were taken to maintain iron in the Fe²⁺ state (e.g., use of extracellular ascorbate). With the use of instantaneous I-V currents (measured after strong depolarization) to isolate the effects on permeation, extracellular Fe²⁺ rapidly blocked currents with 2 mM extracellular Ca²⁺ in a voltage-dependent manner, as described by a Woodhull model with K(D) = 2.5 mM at 0 mV and apparent electrical distance δ = 0.17. Extracellular Fe²⁺ also shifted activation to more-depolarized voltages (by ∼10 mV with 1.8 mM extracellular Fe²⁺) somewhat more strongly than did extracellular Ca²⁺ or Mg²⁺, which is consistent with a Gouy-Chapman-Stern model with surface charge density σ = 1 e(-)/98 Ų and K(Fe) = 4.5 M⁻¹ for extracellular Fe²⁺. In the absence of extracellular Ca²⁺ (and with extracellular Na⁺ replaced by TEA), Fe²⁺ carried detectable, whole-cell, inward currents at millimolar concentrations (73 ± 7 pA at -60 mV with 10 mM extracellular Fe²⁺). With a two-site/three-barrier Eyring model for permeation of Ca(V)3.1 channels, we estimated a transport rate for Fe²⁺ of ∼20 ions/s for each open channel at -60 mV and pH 7.2, with 1 μM extracellular Fe²⁺ (with 2 mM extracellular Ca²⁺). Because Ca(V)3.1 channels exhibit a significant "window current" at that voltage (open probability, ∼1%), Ca(V)3.1 channels represent a likely pathway for Fe²⁺ entry into cells with clinically relevant concentrations of extracellular Fe²⁺.

The influence of Ca substitution on LaFeO3 nanoparticles in terms of structural and magnetic properties.

PubMed

Lin, Qing; Xu, Jianmei; Yang, Fang; Yang, Xingxing; He, Yun

2018-01-01

The nanocrystalline structure of La 1 -x Ca x FeO 3 was prepared by a sol-gel method involving an auto-combustion process. The incorporation of rare-earths in LaFeO 3 induces strain in magnetic properties, especially in terms of the following parameters: replacement amount, oxygen partial pressure, and calcination temperature. To determine the effects of the amount of Ca 2+ ion doping agent and the calcination temperature on the microstructure, particle morphology, and magnetic properties of LaFeO 3 crystal, we performed the following respective analytical methods: X-ray powder diffraction, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy, and vibrating sample magnetometer tests. The orthorhombic structure of LaFeO 3 perovskite did not change even when it was doped with Ca 2+ ions, and its space group continued to be Pnma (No.62). FT-IR spectra confirmed that the main band appearing at 568 cm -1 is due to the antisymmetric stretching vibration of Fe-O-Fe bonds in FeO 6 . The introduction of Ca inhibits the growth of grains but the morphology of particles is improved. With an increasing concentration of Ca 2+ ions, magnetic behavior of the samples also witnessed an increasing trend in a proportionate manner. With an increase in calcination temperature, the enclosed area of the magnetic hysteresis curve of the sample reduced remarkably. The growth of nanoparticles can be restrained with an increase of Ca content that is used as doping agent. The magnetic behavior of La 1 -x Ca x FeO 3 tilts towards G-type antiferromagnetism; the magnetic orientation is achieved from the super exchange interaction of Fe 3+ ions with oxygen ions.

Influence of Magnetite Stoichiometry on the Binding of Emerging Organic Contaminants.

PubMed

Cheng, Wei; Marsac, Rémi; Hanna, Khalil

2018-01-16

While the magnetite stoichiometry (i.e., Fe(II)/Fe(III) ratio) has been extensively studied for the reductive transformation of chlorinated or nitroaromatic compounds, no work exists examining the influence of stoichiometry of magnetite on its binding properties. This study, for the first time, demonstrates that the stoichiometry strongly affects the capacity of magnetite to bind not only quinolone antibiotics such as nalidixic acid (NA) and flumequine (FLU), but also salicylic acid (SA), natural organic matter (humic acid, HA), and dissolved silicates. Fe(II)-amendment of nonstoichiometric magnetite (Fe(II)/Fe(III) = 0.40) led to similar sorbed amounts of NA, FLU, SA, silicates or HA as compared to the stoichiometric magnetite (i.e., Fe(II)/Fe(III) = 0.50). At any pH between 6 and 10, all magnetites exhibiting similar Fe(II)/Fe(III) ratio in the solid phase showed similar adsorption properties for NA or FLU. This enhancement in binding capability of magnetite for NA is still observed in the presence of environmentally relevant ligands (e.g., 10 mg L -1 of HA or 100 μM of silicates). Using surface complexation modeling, it was shown that the NA-magnetite complexation constant does not vary with Fe(II)/Fe(III) between 0.24 and 0.40, but increases by 8 orders of magnitude when Fe(II)/Fe(III) increases from 0.40 to 0.50.

Intracellular Ca2+ regulation by the leech giant glial cell.

PubMed

Nett, W; Deitmer, J W

1998-02-15

1. We have measured the intracellular Ca2+ concentration, [Ca2+]i, and the intracellular Na+ concentration, [Na+]i, with the fluorescent dyes fura-2 (for Ca2+) and SBFI (for Na+) in situ in giant glial cells of the central nervous system of the leech Hirudo medicinalis. 2. The basal [Ca2+]i was 79 +/- 35 nM (n = 27) in cells voltage clamped at -70 to -80 mV, and 75 +/- 29 nM (mean +/- S.D., n = 82) in unclamped cells at a mean membrane potential of -67 +/- 6 mV. 3. Removal of external Na+ evoked a small reversible [Ca2+]i increase of 29 +/- 21 nM (n = 27) in cells voltage clamped at -70 to -80 mV, and of 35 +/- 18 nM (n = 37) in unclamped cells. This [Ca2+]i increase, and the time constant of the subsequent [Ca2+]i recovery after Na+ re-addition, did not change significantly with the holding potential between -110 and -60 mV. 4. The basal [Na+]i was 5.6 +/- 1.3 mM (n = 18). Increasing [Na+]i by inhibiting the Na+-K+ pump with 100 microM ouabain had no effect on the [Ca2+]i rise upon removal of external Na+. 5. The time course of recovery from a [Ca2+]i load mediated by voltage-dependent Ca2+ influx during depolarization in high K+ was unaffected by the removal of external Na+. 6. Cyclopiazonic acid (10 muM), an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a transient increase in [Ca2+]i of 28 +/- 11 nM (n = 5), and significantly slowed the recovery from imposed [Ca2+]i loads. 7. Iontophoretic injection of orthovanadate, an inhibitor of P-type ATPases including the plasma membrane Ca2+-ATPase, caused a persistent increase in the basal [Ca2+]i of 163 +/- 101 nM (n = 5) in standard saline, and of 427 +/- 338 nM in Na+-free saline (n = 5). Vanadate injection significantly slowed the recovery from [Ca2+]i loads. Removal of external Na+ during vanadate injection induced an additional, reversible [Ca2+]i increase of 254 +/- 64 nM (n = 3). 8. The results suggest that the low basal [Ca2+]i in these glial cells is predominantly maintained by a Ca2+-ATPase in the plasma membrane. This ATPase is also the main Ca2+ extruder after an intracellular Ca2+ load, while intracellular stores appear to contribute little to this recovery. A Na+-Ca2+ exchanger seems to play a minor role in the maintenance of basal [Ca2+]i in these cells, but becomes prominent when the plasma membrane Ca2+-ATPase is blocked.

Spectroscopic studies of different brands of cigarettes using laser-induced breakdown spectroscopy

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

Sayyad, M. H.; Saleem, M.; Shah, M.

In this work the technique of laser-induced breakdown spectroscopy (LIBS) has been used for the elemental analysis of cigarettes. For this purpose emission spectra have been measured of eleven different kinds of cigarette brands sold and/or produced in Pakistan. Analysis of the spectral peaks observed shows that Na, Mg, Al, K, Ca, Cr, Fe, Sr and Ba are contained in all brands. Exhibiting the LIBS results, the powerful potential of this method for the identification of the elemental content of cigarettes is demonstrated.

Spectroscopic studies of different brands of cigarettes using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Sayyad, M. H.; Saleem, M.; Shah, M.; Shaikh, N. M.; Baig, M. A.

2008-05-01

In this work the technique of laser-induced breakdown spectroscopy (LIBS) has been used for the elemental analysis of cigarettes. For this purpose emission spectra have been measured of eleven different kinds of cigarette brands sold and/or produced in Pakistan. Analysis of the spectral peaks observed shows that Na, Mg, Al, K, Ca, Cr, Fe, Sr and Ba are contained in all brands. Exhibiting the LIBS results, the powerful potential of this method for the identification of the elemental content of cigarettes is demonstrated.

Determination of palladium and platinum by atomic absorption

USGS Publications Warehouse

Schnepfe, M.M.; Grimaldi, F.S.

1969-01-01

Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

57Fe Mössbauer study of stoichiometric iron-based superconductor CaKFe 4As 4: a comparison to KFe 2As 2 and CaFe 2As 2

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

Bud’ko, Sergey L.; Kong, Tai; Meier, William R.

57Fe Mössbauer spectra at different temperatures between ~5 and ~300 K were measured on an oriented mosaic of single crystals of CaKFe 4 As 4. The data indicate that is a well formed compound with narrow spectral lines, no traces of other, Fe – containing, secondary phases in the spectra and no static magnetic order. There is no discernible feature at the superconducting transition temperature in any of the hyperfine parameters. The temperature dependence of the quadrupole splitting approximately follows the empirical ‘ T 3/2 law’. Furthermore, the hyperfine parameters of CaKFe 4 As 4 are compared with those formore » measured in this work, and the literature data for CaFe 2 As 2, and were found to be in between those for these two, ordered, 122 compounds, in agreement with the gross view of CaKFe 4 As 4 as a structural analog of KFe 2 As 2 and CaFe 2 As 2 that has alternating Ca- and K-layers in the structure.« less

57Fe Mössbauer study of stoichiometric iron-based superconductor CaKFe 4As 4: a comparison to KFe 2As 2 and CaFe 2As 2

DOE PAGES

Bud’ko, Sergey L.; Kong, Tai; Meier, William R.; ...

2017-07-06

57Fe Mössbauer spectra at different temperatures between ~5 and ~300 K were measured on an oriented mosaic of single crystals of CaKFe 4 As 4. The data indicate that is a well formed compound with narrow spectral lines, no traces of other, Fe – containing, secondary phases in the spectra and no static magnetic order. There is no discernible feature at the superconducting transition temperature in any of the hyperfine parameters. The temperature dependence of the quadrupole splitting approximately follows the empirical ‘ T 3/2 law’. Furthermore, the hyperfine parameters of CaKFe 4 As 4 are compared with those formore » measured in this work, and the literature data for CaFe 2 As 2, and were found to be in between those for these two, ordered, 122 compounds, in agreement with the gross view of CaKFe 4 As 4 as a structural analog of KFe 2 As 2 and CaFe 2 As 2 that has alternating Ca- and K-layers in the structure.« less

Studies of structure of calcium-iron phosphate glasses by infrared, Raman and UV-Vis spectroscopies

NASA Astrophysics Data System (ADS)

Li, H. J.; Liang, X. F.; Yu, H. J.; Yang, D. Q.; Yang, S. Y.

2016-06-01

Glasses in the ternary CaO-Fe2O3-P2O5 system were prepared and studied by means of density, differential scanning calorimetry, infrared, Raman and UV-Vis spectroscopies. The results showed that density and molar volume in the glass system decreased with increasing substitution of CaO for Fe2O3. The variation of glass transition temperature and thermal stability was strictly related to the nature of bonding in the vitreous network. Spectroscopic analysis showed that substitution of CaO for Fe2O3 induced an evolution of structural units from pyrophosphate to metaphosphate species indicating the polymerization of phosphate chains and the decrease of non-bridging oxygen concentrations. With increasing substitution of CaO for Fe2O3 The P-O-Ca linkage and (P-O- Ca2+ -O-P) chains participated in the glass network by replacing P-O-Fe bonds. The absorption band of the P-O-Ca stretching mode in the glasses with high CaO content (≥32 mol%) was assigned at around 1084 cm-1. The absorption edge would fall in the region between 332 and 420 nm which are the absorption bands of Fe3+ ions.

Discovery of the Fe-analogue of akimotoite in the shocked Suizhou L6 chondrite

PubMed Central

Bindi, Luca; Chen, Ming; Xie, Xiande

2017-01-01

We report the first natural occurrence of the Fe-analogue of akimotoite, ilmenite-structured MgSiO3, a missing phase among the predicted high-pressure polymorphs of Fe-pyroxene, with the composition (Fe2+0.48Mg0.37Ca0.04Na0.04Mn2+0.03Al0.03Cr3+0.01)Σ=1.00Si1.00O3. The new mineral was approved by the International Mineralogical Association (IMA 2016-085) and named hemleyite in honour of Russell J. Hemley. It was discovered in an unmelted portion of the heavily shocked L6 Suizhou chondrite closely associated to olivine, clinoenstatite and Fe-bearing pyroxene with a composition nearly identical to that of hemleyite. We also report the first single-crystal X-ray diffraction study of a Si-bearing, ilmenite-structured phase. The fact that hemleyite formed in a meteorite exposed to high pressures (<20 GPa) and temperatures (<2000 °C) during impact-induced shocks indicates that it could play a crucial role at the bottom of the Earth’s mantle transition zone and within the uppermost lower mantle. PMID:28198399

Synthetic fluid inclusions in natural quartz I. Compositional types synthesized and applications to experimental geochemistry

NASA Astrophysics Data System (ADS)

Sterner, S. Michael; Bodnar, Robert J.

1984-12-01

Synthetic fluid inclusions having a wide range of geologically applicable compositions in the C-O-H-S-Na-K-Ca-Cl-Cu-Fe system have been formed by healing fractures in inclusion-free natural quartz and by precipitating new quartz overgrowths on an original "seed" crystal. Inclusion types synthesized include: (1) liquid-rich, pure H 2O inclusions of primary and secondary origin, (2) pure H 2O inclusions with the critical density, (3) liquid-rich inclusions containing undersaturated aqueous solutions of NaCl or KCl or CaCl 2, or mixtures of the three salts, (4) H 2O-NaCl inclusions containing halite daughter minerals, (5) H 2O-NaCl-KCl inclusions containing halite and sylvite daughter minerals, (6) H 2O-CO 2 inclusions of various compositions containing liquid H 2O and either CO 2 vapor or CO 2 liquid, or both, at 25°C, (7) H 2O-CO 2-NaCl inclusions containing an aqueous phase, liquid and vapor CO 2, and halite at 25°C, (8) C-O-H inclusions containing liquid H 2O, a CO 2-CH 4 liquid phase and graphite daughter minerals at 25°C, (9) H 2O-NaCl inclusions that contain a chalcopyrite daughter mineral, and (10)inclusions representing trapping of the coexisting, immiscible fluids in the H 2O-NaCl, H 2O-CO 2-NaCl, and Na-C-O-H systems. The inclusions exhibit uniform phase ratios at room temperature, and the temperatures of various phase changes within individual inclusions agree with those predicted from experimental and theoretical data, indicating that the inclusion fluid has the same composition and density as the parent solution. These 'miniature autoclaves' thus may be used to study various problems related to fluid inclusion research, to calibrate analytical equipment used to study natural inclusions, and to study phase equilibria, solubility and PVT relations of a variety of chemical systems.

Synthesis, structure and electrochemical properties of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate

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

Fedotov, Stanislav S.; Skoltech Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 143026 Moscow; Kuzovchikov, Sergey M.

2016-10-15

LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F fluoride-phosphate was synthesized via conventional solid-state and novel freeze-drying routes. The crystal structure was refined based on neutron powder diffraction (NPD) data and validated by electron diffraction (ED) and high-resolution transmission electron microscopy (HRTEM). The alkali ions are ordered in LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F and the transition metals jointly occupy the same crystallographic sites. The oxidation state and oxygen coordination environment of the Fe atoms were verified by {sup 57}Fe Mössbauer spectroscopy. Electrochemical tests of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F cathode material demonstrated a reversible activity of the Fe{sup 3+}/Fe{sup 2+} redox couple at the electrodemore » potential near 3.4 V and minor activity of the Co{sup 3+}/Co{sup 2+} redox couple over 5 V vs Li/Li{sup +}. The material exhibited the discharge capacity of more than 82% (theo.) regarding Fe{sup 3+}/Fe{sup 2+} in the 2.4÷4.6 V vs Li/Li{sup +} potential range. - Graphical abstract: The ball-polyhedral representation of the LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F crystal structure. The MO{sub 4}F{sub 2} units are depicted as blue octahedra, PO{sub 4} units as orange tetrahedra, sodium atoms are designated as yellow (Na1), lithium – red and brown (Li2, Li3 resp.), fluorine – green, oxygen – violet spheres. - Highlights: • Freeze-drying method was successfully applied to the synthesis of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F. • The crystal structure of LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F was refined based on NPD and validated by ED and HRTEM. • LiNaCo{sub 0.5}Fe{sub 0.5}PO{sub 4}F demonstrated a reversible Li de/intercalation in the 2.5÷4.6 V vs Li/Li{sup +} range.« less

Osmolality- and Na+ -dependent effects of hyperosmotic NaCl solution on contractile activity and Ca2+ cycling in rat ventricular myocytes.

PubMed

Ricardo, Rafael A; Bassani, Rosana A; Bassani, José W M

2008-01-01

Hypertonic NaCl solutions have been used for small-volume resuscitation from hypovolemic shock. We sought to identify osmolality- and Na(+)-dependent components of the effects of the hyperosmotic NaCl solution (85 mOsm/kg increment) on contraction and cytosolic Ca(2+) concentration ([Ca(2+)](i)) in isolated rat ventricular myocytes. The biphasic change in contraction and Ca(2+) transient amplitude (decrease followed by recovery) was accompanied by qualitatively similar changes in sarcoplasmic reticulum (SR) Ca(2+) content and fractional release and was mimicked by isosmotic, equimolar increase in extracellular [Na(+)] ([Na(+)](o)). Raising osmolality with sucrose, however, augmented systolic [Ca(2+)](i) monotonically without change in SR parameters and markedly decreased contraction amplitude and diastolic cell length. Functional SR inhibition with thapsigargin abolished hyperosmolality effects on [Ca(2+)](i). After 15-min perfusion, both hyperosmotic solutions slowed mechanical relaxation during twitches and [Ca(2+)](i) decline during caffeine-evoked transients, raised diastolic and systolic [Ca(2+)](i), and depressed systolic contractile activity. These effects were greater with sucrose solution, and were not observed after isosmotic [Na(+)](o) increase. We conclude that under the present experimental conditions, transmembrane Na(+) redistribution apparently plays an important role in determining changes in SR Ca(2+) mobilization, which markedly affect contractile response to hyperosmotic NaCl solutions and attenuate the osmotically induced depression of contractile activity.

Effect of tenderizers combined with organic acids on Escherichia coli O157:H7 thermal resistance in non-intact beef.

PubMed

Yoon, Yohan; Mukherjee, Avik; Belk, Keith E; Scanga, John A; Smith, Gary C; Sofos, John N

2009-07-31

Non-intact beef products include beef cuts that have been ground, mechanically tenderized, restructured, or have been injected with solutions to enhance tenderness and/or flavor. This study examined the effects of tenderizing salts and organic acids on thermal inactivation of Escherichia coli O157:H7 in a ground beef model system simulating non-intact beef products. Ground beef (95% lean; 700 g batches) was mixed (2 min) with nothing (C) or solutions (22 ml) of water (WA), calcium ascorbate (CaA, 0.86%; wt/wt), calcium chloride (CaC, 0.23%; wt/wt), acetic acid (AA, 0.3%; v/wt), citric acid (CA, 0.2%; wt/wt), NaCl (NA, 0.5%; wt/wt), and mixtures of CaA/NA, CaC/NA, AA/NA, CA/NA, CaA/CaC/NA, CaA/AA/NA, CaA/CA/NA, CaC/AA/NA and CaC/CA/NA. Samples (30 g) were extruded into test tubes, inoculated (7 log CFU/g) with E. coli O157:H7 (5-strain mixture), and stored (4 degrees C) overnight. Samples were then cooked to 60 degrees C or 65 degrees C, in a water bath, to simulate rare or medium-rare doneness of beef, respectively. Weight, fat and moisture losses, total bacterial (tryptic soy agar) and E. coli O157:H7 (modified eosin methylene blue agar, and modified sorbitol MacConkey agar) populations were determined after inoculation, storage, and cooking. Fat and moisture losses were not affected by treatment and temperature, while weight losses increased at 65 degrees C and in acid treated samples (60 degrees C). E. coli O157:H7 survivors were generally lower (P<0.05) in acid treated than non-acid treated samples. Pathogen counts in samples treated with tenderizers (CaA, CaC) and NA were not different (P> or =0.05) than those of control samples. Thus, inclusion of organic acids in beef tenderizing recipes may help in thermal inactivation of E. coli O157:H7 that may been transferred to the interior of non-intact products during their production.

Enhanced phosphate removal from wastewater by using in situ generated fresh trivalent Fe composition through the interaction of Fe(II) on CaCO3.

PubMed

Li, Yujie; He, Xiaoman; Hu, Huimin; Zhang, Tingting; Qu, Jun; Zhang, Qiwu

2018-05-21

Excessive existences of nutrients such as phosphate in the aqueous environment remain as a heavy concern although many researches have been reported for dealing with their removal. Based on the understanding toward the interactions of Fe compounds with phosphate and carbonate from many available researches, we designed a very simple and efficient approach for phosphate removal by using in situ generated fresh trivalent Fe composition through the interaction of Fe(II) as FeSO 4 on CaCO 3 . Addition and agitation of Fe(II) and CaCO 3 simultaneously to phosphate solution allowed an amorphous Fe(III)-P or Ca-Fe(III)-P precipitation, with a phosphate removal rate close to 100%, to reduce the residual phosphorus concentration less than 0.03 mg/L from 100 mg/L, reaching the discharge limit, even with the addition amounts of CaCO 3 as low as a stoichiometric ratio of CaCO 3 /PO 4 3- at 0.9 and ratio of Fe(II)/PO 4 3- at 1.5, and the percent of P 2 O 5 in the precipitate was as high as 19.4% enough as phosphate source for fertilizer production. Different from the alkaline process with enough OH - group, the slow hydrolysis of CaCO 3 resulting in low concentration of OH - group for the formation of Fe(OH) 2 , which was oxidized soon by air into trivalent Fe, achieved a continuous generation of fresh ferric composition for phosphate precipitation and could avoid its rapid formation and subsequent transformation into stable FeOOH of large particle size to lose the activity. These results based on the synergistic effect of using CaCO 3 and Fe(II) together may have applications in the treatment of eutrophic wastewater through a process with many advantages of easy operation and low-cost besides the high removal efficiency with phosphate percentage inside the precipitate high enough to serve for fertilizer production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Properties of hydrocarbon- and salt-contaminated flare pit soils in northeastern British Columbia (Canada).

PubMed

Arocena, J M; Rutherford, P M

2005-07-01

Many contaminated sites in Canada are associated with flare pits generated during past petroleum extraction operations. Flare pits are located adjacent to well sites, compressor stations and batteries and are often subjected to the disposal of wastes from the flaring of gas, liquid hydrocarbons and brine water. This study was conducted to evaluate the physical, chemical, electrical and mineral properties of three flare pit soils as compared to adjacent control soils. Results showed that particle size distribution, pH, total N, cation exchange capacity, exchangeable Mg(2+), and sodium adsorption ratio were similar in soils from flare pits and control sites. Total C, exchangeable Ca(2+), K(+) and Na(+), soluble Ca(2+), Mg(2+), K(+) and Na(+) and electrical conductivity were higher in flare pit soils compared to control soils. X-ray diffraction and scanning electron microscopic analyses showed the presence of gypsum [CaSO(4).2H(2)O], dolomite [CaMg(CO(3))(2)], pyrite [FeS(2)], jarosite [KFe(3)(OH)(6)(SO(4))(2)], magnesium sulphate, oxides of copper and iron+copper in salt efflorescence observed in flare pit soils. Soils from both flare pits and control sites contained mica, kaolonite and 2:1 expanding clays. The salt-rich materials altered the ionic equilibria in the flare pit soils; K(Mg-Ca) selectivity coefficients in control soils were higher compared to contaminated soils. The properties of soils (e.g., high electrical conductivity) affected by inputs associated with oil and gas operations might render flare pit soils less conducive to the establishment and growth of common agricultural crops and forest trees.

Thermodynamic Analysis of Secondary Minerals Stability in Altered Carbonatites of the Oldoinyo Lengai Volcano, Northern Tanzania

NASA Astrophysics Data System (ADS)

Perova, E. N.; Zaitsev, A. N.

2017-12-01

Carbonatites from the Oldoinyo Lengai volcano, northern Tanzania, are unstable under normal atmospheric conditions. Owing to carbonatite interaction with water, the major minerals—gregoryite Na2(CO3), nyerereite Na2Ca(CO3)2, and sylvite KCl—are dissolved and replaced with secondary low-temperature minerals: thermonatrite Na2(CO3) · H2O, trona Na3(CO3)(HCO3) · 2H2O, nahcolite Na(HCO3), pirssonite Na2Ca(CO3)2 · 2H2O, calcite Ca(CO3), and shortite Na2Ca2(CO3)3. Thermodynamic calculations show that the formation of secondary minerals in Oldoinyo Lengai carbonatites are controlled by the pH of the pore solution, H2O and CO2 fugacity, and the ratio of Ca and Na activity in the Na2O-CaO-CO2-H2O system.

Medium-resolution Spectroscopy of Red Giant Branch Stars in ω Centauri

NASA Astrophysics Data System (ADS)

An, Deokkeun; Lee, Young Sun; In Jung, Jae; Rey, Soo-Chang; Rhee, Jaehyon; Lee, Jae-Woo; Lee, Young-Wook; Joe, Young Hoon

2017-10-01

We present [Fe/H] and [Ca/Fe] of ˜600 red giant branch (RGB) members of the globular cluster Omega Centauri (ω {Cen}). We collect medium-resolution (R˜ 2000) spectra using the Blanco 4 m telescope at the Cerro Tololo Inter-American Observatory equipped with Hydra, the fiber-fed multi-object spectrograph. We demonstrate that blending of stellar light in optical fibers severely limits the accuracy of spectroscopic parameters in the crowded central region of the cluster. When photometric temperatures are taken in the spectroscopic analysis, our kinematically selected cluster members, excluding those that are strongly affected by flux from neighboring stars, include relatively fewer stars at intermediate metallicity ([{Fe}/{{H}}]˜ -1.5) than seen in the previous high-resolution survey for brighter giants in Johnson & Pilachowski. As opposed to the trend of increasing [Ca/Fe] with [Fe/H] found by those authors, our [Ca/Fe] estimates, based on Ca II H & K measurements, show essentially the same mean [Ca/Fe] for most of the metal-poor and metal-intermediate populations in this cluster, suggesting that mass- or metallicity-dependent SN II yields may not be necessary in their proposed chemical evolution scenario. Metal-rich cluster members in our sample show a large spread in [Ca/Fe], and do not exhibit a clear bimodal distribution in [Ca/Fe]. We also do not find convincing evidence for a radial metallicity gradient among RGB stars in ω {Cen}.

Variations in iron and calcium abundances during solar flares

NASA Astrophysics Data System (ADS)

Antonucci, E.; Martin, R.

1995-07-01

Evidence for variations in iron and calcium abundances during the impulsive phase of solar flares has been obtained by analyzing the Ca XIX and Fe XXV spectra, detected with the Bent Crystal Spectrometer of the Solar Maximum Mission. The plasma thermal conditions have been investigated by considering different temperature indicators: namely, the temperatures TCa and TFe, derived from the intensity ratios of the dielectronic recombination satellites to the resonance line, and the temperature TCaFe, calculated from the ratio of the resonance lines of Ca XIX and Fe XXV, which is also depending on the Fe/Ca abundance ratio. The observed values of TCa and TFe can be ascribed to the specific characteristics of the plasma therma distribution, the corresponding values of TCaFe can be explained by allowing also for variations in the Fe/Ca abundance ratio relative to the photospheric ratio by a factor within 0.2 and 2.4. According to the observed abundance variations, the events analyzed can be divided in Ca-rich and Fe-rich flares.

Observational restrictions on sodium and aluminium abundance variations in evolution of the galaxy

NASA Astrophysics Data System (ADS)

Menzhevitski, V. S.; Shimanskaya, N. N.; Shimansky, V. V.; Sakhibullin, N. A.

2013-07-01

In this paper we construct and analyze the uniform non-LTE distributions of the aluminium ([Al/Fe]-[Fe/H]) and sodium ([Na/Fe]-[Fe/H]) abundances in the sample of 160 stars of the disk and halo of our Galaxy with metallicities within -4.07 ≤ [Fe/H] ≤ 0.28. The values of metallicity [Fe/H] and microturbulence velocity ξ turb indices are determined from the equivalent widths of the Fe II and Fe I lines. We estimated the sodium and aluminium abundances using a 21-level model of the Na I atom and a 39-level model of the Al I atom. The resulting LTE distributions of [Na/Fe]-[Fe/H] and [Al/Fe]-[Fe/H] do not correspond to the theoretical predictions of their evolution, suggesting that a non-LTE approach has to be applied to determine the abundances of these elements. The account of non-LTE corrections reduces by 0.05-0.15 dex the abundances of sodium, determined from the subordinate lines in the stars of the disk with [Fe/H] ≥ -2.0, and by 0.05-0.70 dex (with a strong dependence on metallicity) the abundances of [Na/Fe], determined by the resonance lines in the stars of the halo with [Fe/H] ≤ -2.0. The non-LTE corrections of the aluminium abundances are strictly positive and increase from 0.0-0.1 dex for the stars of the thin disk (-0.7 ≤ [Fe/H] ≤ 0.28) to 0.03-0.3 dex for the stars of the thick disk (-1.5 ≤ [Fe/H] ≤ -0.7) and 0.06-1.2 dex for the stars of the halo ([Fe/H] ≤ -2.0). The resulting non-LTE abundances of [Na/Fe] reveal a scatter of individual values up to Δ[Na/Fe] = 0.4 dex for the stars of close metallicities. The observed non-LTE distribution of [Na/Fe]-[Fe/H] within 0.15 dex coincides with the theoretical distributions of Samland and Kobayashi et al. The non-LTE aluminium abundances are characterized by a weak scatter of values (up to Δ[Al/Fe] = 0.2 dex) for the stars of all metallicities. The constructed non-LTE distribution of [Al/Fe]-[Fe/H] is in a satisfactory agreement to 0.2 dex with the theoretical data of Kobayashi et al., but strongly differs (up to 0.4 dex) from the predictions of Samland.

NASICON-related Na3.4Mn0.4Fe1.6(PO4)3

PubMed Central

Yatskin, Michael M.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Ogorodnyk, Ivan V.; Slobodyanik, Nikolay S.

2012-01-01

The solid solution, sodium [iron(III)/manganese(II)] tris­(orthophosphate), Na3.4Mn0.4Fe1.6(PO4)3, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)2(PO4)3] framework is built up from an (Mn/Fe)O6 octa­hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO4 tetra­hedron (site symmetry .2). The Na+ cations are distributed over two partially occupied sites in the cavities of the framework. One Na+ cation (site symmetry -3.) is surrounded by six O atoms, whereas the other Na+ cation (site symmetry .2) is surrounded by eight O atoms. PMID:22807697

High pressure structural investigation on alluaudites Na{sub 2}Fe{sub 3}(PO{sub 4}){sub 3}-Na{sub 2}FeMn{sub 2}(PO{sub 4}){sub 3} system

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

Gao, Jing; Huang, Weifeng; Qin, Shan

Alluaudites are promising electrochemical materials benefited from the open structure. Structural variations of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) system have been studied by synchrotron radiation X-ray diffraction combined with diamond anvil cell technique up to ~10 GPa at room temperature. No phase transition is observed. The excellent structural stability is mainly due to the flexible framework plus strong covalent P-O bond. Mn{sup 2+} instead of Fe can be described as Na{sup +}+2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy. The replacement of Fe with larger Mn{sup 2+} is equivalentmore » to applying negative chemical pressure to the material. And it causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe. External pressure effect produces anisotropic lattice shrinkage. Structural considerations related to these variations and promising application prospects are discussed. - Graphical abstract: Figure 1 The crystal structure of alluaudites Na{sub 2}M{sub 3}(PO{sub 4}){sub 3} (M{sub 3}=Fe{sub 3}, Fe{sub 2}Mn and FeMn{sub 2}) projected along the c-axis. Alluaudites adopt a flexible framework plus strong covalent P-O bond, which contribute to excellent structural stability up to ~10 GPa. Mn{sup 2+} instead of Fe can be described as Na{sup ++}2Fe{sup 2+}→Mn{sup 2+}+Fe{sup 3+}+□ where □ represents a lattice vacancy, and it is equivalent to applying negative chemical pressure to the host. The substitution causes a more compressible b-axis, lattice expansion, structural compressibility and intensifies the core/electron-electron interactions of Fe.« less

Ilyukhinite (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 • 3H2O, a New Mineral of the Eudialyte Group

NASA Astrophysics Data System (ADS)

Chukanov, N. V.; Rastsvetaeva, R. K.; Rozenberg, K. A.; Aksenov, S. M.; Pekov, I. V.; Belakovsky, D. I.; Kristiansen, R.; Van, K. V.

2017-12-01

A new eudialyte-group mineral, ilyukhinite, ideally (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 · 3H2O, has been found in peralkaline pegmatite at Mt. Kukisvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. It occurs as brownish orange, with vitreous luster anhedral grains up to 1 mm across in hydrothermally altered peralkaline rock, in association with aegirine, murmanite, albite, microcline, rhabdophane-(Ce), fluorite, sphalerite and molybdenite. The Mohs hardness is 5; cleavage is not observed. D meas 2.67(2), D calc 2.703 g/cm3. Ilyukhinite is optically uniaxial (-): ω = 1.585(2), ɛ = 1.584(2). The IR spectrum is given. The average chemical composition of ilyukhinite (wt %; electron microprobe, ranges given in parentheses; H2O determined by gas chromatography) is as follows: 3.07 (3.63-4.43) Na2O, 0.32 (0.28-0.52) K2O, 10.63 (10.26-10.90) CaO, 3.06 (2.74-3.22) MnO, 1.15 (0.93-1.37) FeO, 0.79 (0.51-0.89) La2O3, 1.21 (0.97-1.44) Ce2O3, 0.41 (0.30-0.56) Nd2O3, 0.90 (0.77-1.12) TiO2, 10.94 (10.15-11.21) ZrO2, 1.40 (0.76-1.68) Nb2O5, 51.24 (49.98-52.28) SiO2, 1.14 (0.89-1.37) SO3, 0.27 (0.19—0.38) Cl, 10.9(5 )H2O,-0.06-O = C1, total is 98.27. The empirical formula is H36.04(Na3.82K0.20)(Ca5.65Ce0.22La0.14Nd0.07)(Mn1.285Fe0.48)(Zr2.645Ti0.34)Nb0.31Si25.41S0.42Cl0.23O86.82. The crystal structure has been solved ( R = 0.046). Ilyukhinite is trigonal, R3 m; a = 14.1695(6) Å, b = 31.026(1) Å, V = 5394.7(7) Å3, Z = 3. The strongest XRD reflections [ d, Å (I, %) ( hkl)] are 11.44 (82) (101), 7.09 (70) (110), 6.02 (44) (021), 4.371 (89) 205), 3.805 (47) (303, 033), 3.376 (41) (131), 2.985 (100) (315, 128), 2.852 (92) (404). Ilyukhinite was named in memory of Vladimir V. Ilyukhin (1934-1982), an outstanding Soviet crystallographer. The type specimen of ilyukhinite has been deposited in the collection of the Natural History Museum, University of Oslo, Norway.

A first principles study on newly proposed (Ca/Sr/Ba)Fe2Bi2 compounds with their parent compounds

NASA Astrophysics Data System (ADS)

Sundareswari, M.; Jayalakshmi, D. S.; Viswanathan, E.

2016-02-01

The structural, electronic, bonding and magnetic properties of newly proposed iron-based compounds viz., CaFe2Bi2, SrFe2Bi2, BaFe2Bi2 with their Fermi surface topology are reported here for the first time by means of first principles calculation. All these properties of newly proposed compounds are compared and analysed along with their respective parent compounds namely (Ca,Sr,Ba)Fe2As2.

Crystal Phases Formed in a CaO-Fe2O3 System Under a High Cooling Rate in Air

NASA Astrophysics Data System (ADS)

Kashiwaya, Yoshiaki

2017-12-01

A CaO-Fe2O3 system is a fundamental binary system for the iron ore sintering process. Although the basic reactions have been investigated since the 1960s, melting and solidification caused by the combustion of coke results in an unstable state owing to extreme temperature variations. In this study, using a hot thermocouple method, samples of 10 pct CaO-90 pct Fe2O3 and 20 pct CaO-80 pct Fe2O3 were melted on a thermocouple and quenched with several techniques. The obtained samples were precisely examined by XRD. It was found that the sample containing 10 pct CaO-90 pct Fe2O3 changed to 10 pct CaO-13 pct FeO-77 pct Fe2O3 under an oxygen partial pressure ( P_{{{O}2 }} ) of 0.21 during melting. For the 10 pct CaO sample, the crystal phases found at a low cooling rate (509 K/s) were WFss, C4WF8 (C: CaO, W: FeO, F: Fe2O3), and C2W4F9. When the sample composition was 20 pct CaO, the precipitated crystal phases were C4WF4, C4F7, and C4WF8. On the other hand, the crystal phases for high cooling rates (1590 and 7900 K/s) with 10 pct CaO were WFss (solid solution of WF and F), F, and C2W4F9. The formation of the equilibrium phases WFss, F, C4WF4, and C4WF8 can be understood by examining the isothermal section of the phase diagrams, while the unstable phases C2W4F9 and C4F7 are discussed on the basis of the reactions under an equilibrium state.

Role of Na+/Ca2+ Exchangers in Therapy Resistance of Medulloblastoma Cells.

PubMed

Pelzl, Lisann; Hosseinzadeh, Zohreh; Al-Maghout, Tamer; Singh, Yogesh; Sahu, Itishri; Bissinger, Rosi; Schmidt, Sebastian; Alkahtani, Saad; Stournaras, Christos; Toulany, Mahmoud; Lang, Florian

2017-01-01

Alterations of cytosolic Ca2+-activity ([Ca2+]i) are decisive in the regulation of tumor cell proliferation, migration and survival. Transport processes participating in the regulation of [Ca2+]i include Ca2+ extrusion through K+-independent (NCX) and/or K+-dependent (NCKX) Na+/Ca2+-exchangers. The present study thus explored whether medulloblastoma cells express Na+/Ca2+-exchangers, whether expression differs between therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells, and whether Na+/Ca2+-exchangers participate in the regulation of cell survival. In therapy sensitive D283 and therapy resistant UW228-3 medulloblastoma cells transcript levels were estimated by RT-PCR, protein abundance by Western blotting, cytosolic Ca2+-activity ([Ca2+]i) from Fura-2-fluorescence, Na+/ Ca2+-exchanger activity from the increase of [Ca2+]i (Δ[Ca2+]i) and from whole cell current (Ica) following abrupt replacement of Na+ containing (130 mM) and Ca2+ free by Na+ free and Ca2+ containing (2 mM) extracellular perfusate as well as cell death from PI -staining and annexin-V binding in flow cytometry. The transcript levels of NCX3, NCKX2, and NCKX5, protein abundance of NCX3, slope and peak of Δ[Ca2+]i as well as Ica were significantly lower in therapy sensitive D283 than in therapy resistant UW228-3 medulloblastoma cells. The Na+/Ca2+-exchanger inhibitor KB-R7943 (10 µM) significantly blunted Δ[Ca2+]i, and augmented the ionizing radiation-induced apoptosis but did not significantly modify clonogenicity of medulloblastoma cells. Apoptosis was further enhanced by NCX3 silencing. Na+/Ca2+-exchanger activity significantly counteracts apoptosis but does not significantly affect clonogenicity after radiation of medulloblastoma cells. © 2017 The Author(s). Published by S. Karger AG, Basel.

[Effect of NaHCO3 stress on uptake and transportation of Na+, K+ and Ca2+ in three shrub species].

PubMed

Mao, Gui-Lian; Li, Guo-Qi; Xu, Xing; Zhang, Xin-Xue

2014-03-01

We detected absorption and transportation of ions in the leaves of Atriplex nummularia, Atriplex canescens and Lycium barbarum under NaHCO3 stress (300 mmol x L(-1)) by using atomic absorption spectrophotometry and non-invasive ion flux measurement. The results showed that leaves of the A. nummularia, A. canescens and L. barbarum exhibited a high capacity to induce the Na+ accumulation when compared with that of control. The higher the concentration of NaHCO3 treatment, the more Na+ accumulated in the leaves of the three plants under experimental condition. L. barbarum showed a higher Na+ efflux in the mesophyll cells, whereas A. nummularia and A. canescens showed a relative lower efflux. A lower K+ content and a higher Na+/K+ ratio were detected in leaves of A. nummularia and L. barbarum. However, a higher K+ content and a lower Na+/K+ ratio were seen in leaves of A. canescens. Due to induction of Ca2+ efflux under the NaHCO3 treatment, a lower Ca2+ content and a higher Na+/Ca2+ ratio were observed in L. barbarum. On the contrary, a higher Ca2+ influx was observed in A. nummularia and A. canescens. These results suggested that the three shrubs species had different Na+ segmentation strategies. The accumulation of Na+ inhibited Ca2+ absorption in leaves of L. barbarum, while in the A. nummularia and A. canescens, Ca2+ influx induced [Ca2+]cyt which preserved a less-depolarized PM and then inhibited K efflux. The maintaining of cellular K+/Na+ homeostasis in A. nummularia and A. canescens might be achieved by the induction of [Ca2+]cyt under the NaHCO3 treatment.

Activation Thermodynamics and H/D Kinetic Isotope Effect of the Hox to HredH+ Transition in [FeFe] Hydrogenase.

PubMed

Ratzloff, Michael W; Wilker, Molly B; Mulder, David W; Lubner, Carolyn E; Hamby, Hayden; Brown, Katherine A; Dukovic, Gordana; King, Paul W

2017-09-20

Molecular complexes between CdSe nanocrystals and Clostridium acetobutylicum [FeFe] hydrogenase I (CaI) enabled light-driven control of electron transfer for spectroscopic detection of redox intermediates during catalytic proton reduction. Here we address the route of electron transfer from CdSe→CaI and activation thermodynamics of the initial step of proton reduction in CaI. The electron paramagnetic spectroscopy of illuminated CdSe:CaI showed how the CaI accessory FeS cluster chain (F-clusters) functions in electron transfer with CdSe. The H ox →H red H + reduction step measured by Fourier-transform infrared spectroscopy showed an enthalpy of activation of 19 kJ mol -1 and a ∼2.5-fold kinetic isotope effect. Overall, these results support electron injection from CdSe into CaI involving F-clusters, and that the H ox →H red H + step of catalytic proton reduction in CaI proceeds by a proton-dependent process.

3D NLTE analysis of the most iron-deficient star, SMSS0313-6708

NASA Astrophysics Data System (ADS)

Nordlander, T.; Amarsi, A. M.; Lind, K.; Asplund, M.; Barklem, P. S.; Casey, A. R.; Collet, R.; Leenaarts, J.

2017-01-01

Context. Models of star formation in the early universe require a detailed understanding of accretion, fragmentation and radiative feedback in metal-free molecular clouds. Different simulations predict different initial mass functions of the first stars, ranging from predominantly low-mass (0.1-10 M⊙), to massive (10-100 M⊙), or even supermassive (100-1000 M⊙). The mass distribution of the first stars should lead to unique chemical imprints on the low-mass second and later generation metal-poor stars still in existence. The chemical composition of SMSS0313-6708, which has the lowest abundances of Ca and Fe of any star known, indicates it was enriched by a single massive supernova. Aims: The photospheres of metal-poor stars are relatively transparent in the UV, which may lead to large three-dimensional (3D) effects as well as departures from local thermodynamical equilibrium (LTE), even for weak spectral lines. If 3D effects and departures from LTE (NLTE) are ignored or treated incorrectly, errors in the inferred abundances may significantly bias the inferred properties of the polluting supernovae. We redetermine the chemical composition of SMSS0313-6708by means of the most realistic methods available, and compare the results to predicted supernova yields. Methods: A 3D hydrodynamical Staggermodel atmosphere and 3D NLTE radiative transfer were applied to obtain accurate abundances for Li, Na, Mg, Al, Ca and Fe. The model atoms employ realistic collisional rates, with no calibrated free parameters. Results: We find significantly higher abundances in 3D NLTE than 1D LTE by 0.8 dex for Fe, and 0.5 dex for Mg, Al and Ca, while Li and Na are unaffected to within 0.03 dex. In particular, our upper limit for [Fe/H] is now a factor ten larger, at [Fe/H] < -6.53 (3σ), than previous estimates based on ⟨ 3D ⟩NLTE (I.e., using averaged 3D models). This higher estimate is due to a conservative upper limit estimation, updated NLTE data, and 3D-⟨ 3D ⟩NLTE differences, all of which lead to a higher abundance determination. Conclusions: We find that supernova yields for models in a wide range of progenitor masses reproduce the revised chemical composition. In addition to massive progenitors of 20-60 M⊙ exploding with low energies (1-2 B, where 1 B = 1051 erg), we also find good fits for progenitors of 10 M⊙, with very low explosion energies (<1 B). We cannot reconcile the new abundances with supernovae or hypernovae with explosion energies above 2.5 B, nor with pair-instability supernovae.

Investigations on FCAM-III (Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3

NASA Astrophysics Data System (ADS)

Zöll, Klaus; Kahlenberg, Volker; Krüger, Hannes; Tropper, Peter

2018-02-01

In the course of a systematic study of a part of the quaternary system Fe2O3-CaO-Al2O3-MgO (FCAM) the previously unknown compound Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 (FCAM-III) has been synthesized. By analogy with the so-called SFCA series [1-5], our investigation in the system of FCAM shows the existence of a stoichiometric homologous series M14+6nO20+8n, where M = Fe, Ca, Al, Mg and n = 1 or 2. In air, we can prove the formation of coexisting FCAM-III and FCAM-I solid solutions at 1400 °C. By increasing the temperature up to 1425 °C FCAM-I disappears completely and FCAM-III co-exists with magnesiumferrite and a variety of calcium iron oxides. At 1450 °C FCAM-III breaks down to a mixture of FCAM-I again as well as magnesioferrite and melt. Small single-crystals of FCAM-III up to 35 μm in size could be retrieved from the 1425 °C experiment and were subsequently characterized using electron microprobe analysis and synchroton X-ray single-crystal diffraction. Finally the Fe2+/Fetot ratio was calculated from the total iron content based on the crystal-chemical formula obtained from EMPA measurements and charge balance considerations. FCAM-III or Ca2.38Mg2.09Fe3+10.61Fe2+1.59Al9.33O36 has a triclinic crystal structure (space group P 1 ̅). The basic crystallographic data are: a = 10.223(22) Å, b = 10.316(21) Å, c = 14.203(15) Å, α = 93.473(50)°, β = 107.418(67)°, γ = 109.646(60)°, V = 1323.85(2) ų, Z = 1. Using Schreinemaker's technique to analyze the phase relations in the system Fe2O3-CaO-Al2O3-MgO it was possible to obtain the semi-quantitative stability relations between the participating phases and construct a topologically correct phase sequence as a function of T and fO2. The analysis shows that Ca2Al0.5Fe1.5O5 (C2A0.25F0.75) and CaAl1.5Fe2.5O7 (CA0.75F1.25) with higher calculated Fe2+ contents are preferably formed at lower oxygen fugacity and react to CaAl0.5Fe1.5O4 (CA0.25F0.75) by increasing fO2. Spinel-type magnesium-aluminium-ferrite (Mg,Fe2+)Fe3+1.25Al0.75O4 or (MA0.375F0.625) is the typical phase which occurs at high temperature (1400 °C).

Single agglutinates: A comparative study of compositions of agglutinitic glass, whole-grain, bulk soil, and FMR

NASA Technical Reports Server (NTRS)

Basu, A.; Robinson, R.; Mckay, D. S.; Blanchard, D. P.; Morris, R. V.; Wentworth, Susan J.

1994-01-01

Previous workers on single agglutinates have variously interpreted the composition of agglutinitic glass to represent impact melts of (1) bulk soil, (2) mixed components in finer sizes, and (3) microtargets. Separately, Papike has argued in favor of fusion of the finest fraction of bulk soils. Thirty-four single agglutinates were hand-picked from the mature Apollo 16 soil 61181 (I(sub s)/FeO = 82) and the FMR and chemical composition (INAA for Fe, Sc, Sm, Co, Ni, and Cr) of each agglutinate particle were measured. Thirteen of these single agglutinates were selected for electron beam microanalysis and imaging. Less than 1 micron spots were analyzed (for Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, Mn, Fe, Ni, and Ba) on pure glassy areas (approximately ten in each particle) selected on the basis of optical and BSE images (avoiding all clasts and inclusions) with an electron microprobe to obtain average glass compositions of each single agglutinate.

Guanosine 5′-monophosphate-chelated calcium and iron feed additives maintains egg production and prevents Salmonella Gallinarum in experimentally infected layers

PubMed Central

Noh, Hye-Ji; Kim, HeeKyong; Heo, Su Jeong; Cho, Hyang Hyun

2017-01-01

We evaluated the effects of guanosine 5′-monophosphate (GMP)-chelated calcium and iron (CaFe-GMP) on health and egg quality in layers experimentally infected with Salmonella Gallinarum. In this study, a CaFe-GMP feed additive was added to a commercial layer feed and fed to layers over a four-week period. All were inoculated with Salmonella Gallinarum. Body weight, mortality, clinical symptoms, and poultry production including feed intake, egg production, egg loss, and feed conversion rate were observed, and Salmonella Gallinarum was re-isolated from the liver, spleen, and cecum of the layers. All tested internal organs for the CaFe-GMP additive group exhibited significantly lower re-isolation numbers of Salmonella Gallinarum and less severe pathological changes than those in the control group, indicating that the CaFe-GMP feed supplement induced bacterial clearance and increased resistance to Salmonella Gallinarum. Additionally, due to the inhibitory action of CaFe-GMP on the growth of Salmonella Gallinarum, the CaFe-GMP additive group exhibited better egg production, including a higher laying rate and fewer broken eggs. The results suggest that a 0.16% CaFe-GMP additive may help prevent salmonellosis in the poultry industry. PMID:28057911

Electrogenic Na+/Ca2+ Exchange

PubMed Central

Danaceau, Jonathan P.; Lucero, Mary T.

2000-01-01

Olfactory receptor neurons (ORNs) from the squid, Lolliguncula brevis, respond to the odors l-glutamate or dopamine with increases in internal Ca2+ concentrations ([Ca2+]i). To directly asses the effects of increasing [Ca2+]i in perforated-patched squid ORNs, we applied 10 mM caffeine to release Ca2+ from internal stores. We observed an inward current response to caffeine. Monovalent cation replacement of Na+ from the external bath solution completely and selectively inhibited the caffeine-induced response, and ruled out the possibility of a Ca2+-dependent nonselective cation current. The strict dependence on internal Ca2+ and external Na+ indicated that the inward current was due to an electrogenic Na+/Ca2+ exchanger. Block of the caffeine-induced current by an inhibitor of Na+/Ca2+ exchange (50–100 μM 2′,4′-dichlorobenzamil) and reversibility of the exchanger current, further confirmed its presence. We tested whether Na+/Ca2+ exchange contributed to odor responses by applying the aquatic odor l-glutamate in the presence and absence of 2′,4′-dichlorobenzamil. We found that electrogenic Na+/Ca2+ exchange was responsible for ∼26% of the total current associated with glutamate-induced odor responses. Although Na+/Ca2+ exchangers are known to be present in ORNs from numerous species, this is the first work to demonstrate amplifying contributions of the exchanger current to odor transduction. PMID:10828249

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca 1 - x La x FeAs 2

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

Kang, Chang-Jong; Birol, Turan; Kotliar, Gabriel

The recently discovered high-T c superconductor Ca 1-xLa xFeAs 2 is a unique compound not just because of its low-symmetry crystal structure but also because of its electronic structure, which hosts Dirac-like metallic bands resulting from (spacer) zigzag As chains. We present a comprehensive first-principles theoretical study of the electronic and crystal structures of Ca 1-xLa xFeAs 2. After discussing the connection between the crystal structure of the 112 family, which Ca 1-xLa xFeAs 2 is a member of, with the other known structures of Fe pnictide superconductors, we check the thermodynamic phase stability of CaFeAs 2, and similar hyphotheticalmore » compounds SrFeAs 2 and BaFeAs 2 which, we find, are slightly higher in energy. We calculate the optical conductivity of Ca 1-xLa xFeAs 2 using the DFT+DMFT method and predict a large in-plane resistivity anisotropy in the normal phase, which does not originate from electronic nematicity, but is enhanced by the electronic correlations. In particular, we predict a 0.34 eV peak in the yy component of the optical conductivity of the 30% La-doped compound, which corresponds to coherent interband transitions within a fast-dispersing band arising from the zigzag As chains, which are unique to this compound. We also study the Landau free energy for Ca 1-xLa xFeAs 2 including the order parameter relevant for the nematic transition and find that the free energy does not have any extra terms that could induce ferro-orbital order. This explains why the presence of As chains does not broaden the nematic transition in Ca 1-xLa xFeAs 2.« less

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca 1 - x La x FeAs 2

DOE PAGES

Kang, Chang-Jong; Birol, Turan; Kotliar, Gabriel

2017-01-17

The recently discovered high-T c superconductor Ca 1-xLa xFeAs 2 is a unique compound not just because of its low-symmetry crystal structure but also because of its electronic structure, which hosts Dirac-like metallic bands resulting from (spacer) zigzag As chains. We present a comprehensive first-principles theoretical study of the electronic and crystal structures of Ca 1-xLa xFeAs 2. After discussing the connection between the crystal structure of the 112 family, which Ca 1-xLa xFeAs 2 is a member of, with the other known structures of Fe pnictide superconductors, we check the thermodynamic phase stability of CaFeAs 2, and similar hyphotheticalmore » compounds SrFeAs 2 and BaFeAs 2 which, we find, are slightly higher in energy. We calculate the optical conductivity of Ca 1-xLa xFeAs 2 using the DFT+DMFT method and predict a large in-plane resistivity anisotropy in the normal phase, which does not originate from electronic nematicity, but is enhanced by the electronic correlations. In particular, we predict a 0.34 eV peak in the yy component of the optical conductivity of the 30% La-doped compound, which corresponds to coherent interband transitions within a fast-dispersing band arising from the zigzag As chains, which are unique to this compound. We also study the Landau free energy for Ca 1-xLa xFeAs 2 including the order parameter relevant for the nematic transition and find that the free energy does not have any extra terms that could induce ferro-orbital order. This explains why the presence of As chains does not broaden the nematic transition in Ca 1-xLa xFeAs 2.« less

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.

Detailed abundances from integrated-light spectroscopy: Milky Way globular clusters

NASA Astrophysics Data System (ADS)

Larsen, S. S.; Brodie, J. P.; Strader, J.

2017-05-01

Context. Integrated-light spectroscopy at high spectral resolution is rapidly maturing as a powerful way to measure detailed chemical abundances for extragalactic globular clusters (GCs). Aims: We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Methods: Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved Hubble Space Telescope colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. Results: The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than 0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the α-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr/Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg/Fe] ratios also agree well with literature data. Our [Na/Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba/Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Conclusions: Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects, might further reduce some of the remaining offsets. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme(s) 095.B-0677(A).Tables A.1-A.7 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/601/A96

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends

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

Onori, Roberta, E-mail: Roberta.onori@uniroma1.it; Polettini, Alessandra; Pomi, Raffaella

2011-02-15

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl{sub 2} or CaSO{sub 4}, which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl{sub 2} exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect onmore » mechanical strength was also observed when CaSO{sub 4} was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature.« less

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends.

PubMed

Onori, Roberta; Polettini, Alessandra; Pomi, Raffaella

2011-02-01

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl(2) or CaSO(4), which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl(2) exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect on mechanical strength was also observed when CaSO(4) was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature. Copyright © 2010 Elsevier Ltd. All rights reserved.

Compositional limits and analogs of monoclinic triple-chain silicates

NASA Astrophysics Data System (ADS)

Jenkins, David M.; Gilleaudeau, Geoffrey J.; Kawa, Cynthia; Dibiase, Jaclyn M.; Fokin, Maria

2012-08-01

Growing recognition of triple-chain silicates in nature has prompted experimental research into the conditions under which they can form and the extent of solid solution that is feasible for some key chemical substitutions. Experiments were done primarily in the range of 0.1-0.5 GPa and 200-850 °C for durations of 18-1,034 h. A wide range of bulk compositions were explored in this study that can be classified broadly into two groups: those that are Na free and involve various possible chemical substitutions into jimthompsonite (Mg10Si12O32(OH)4), and those that are Na bearing and involve chemical substitutions into the ideal end-member Na4Mg8Si12O32(OH)4. Numerous attempts to synthesize jimthompsonite or clinojimthompsonite were unsuccessful despite the type of starting material used (reagent oxides, magnesite + SiO2, talc + enstatite, or anthophyllite). Similarly, the chemical substitutions of F- for OH-, Mn2+, Ca2+, or Fe2+ for Mg2+, and 2Li+ for Mg2+ and a vacancy were unsuccessful at nucleating triple-chain silicates. Conversely, nearly pure yields of monoclinic triple-chain silicate could be made at temperatures of 440-630 °C and 0.2 GPa from the composition Na4Mg8Si12O32(OH)4, as found in previous studies, though its composition is most likely depleted in Na as evidenced by electron microprobe and FTIR analysis. Pure yields of triple-chain silicate were also obtained for the F-analog composition Na4Mg8Si12O32F4 at 550-750 °C and 0.2-0.5 GPa if a flux consisting of Na-halide salt and water in a 2:1 ratio by weight was used. In addition, limited chemical substitution could be documented for the substitutions of 2 Na+ for Na+ + H+ and of Mg2+ + vacancy for 2Na+. For the former, the Na content appears to be limited to 2.5 cations giving the ideal composition of Na2.5Mg8Si12O30.5(OH)5.5, while for the latter substitution the Na content may go as low as 1.1 cations giving the composition Na1.1Mg9.4Si12O31.9(OH)4.1 based on a fixed number of Si cations. Further investigation involving Mg for Na cation exchange may provide a pathway for the synthesis of Na-free clinojimthompsonite. Fairly extensive solid solution was also observed for triple-chain silicates made along the compositional join Na4Mg8Si12O32(OH)4-Ca2Mg8Si12O32(OH)4 where the limit of Ca substitution at 450 °C and 0.2 GPa corresponds to Na0.7Ca1.8Mg7.8Si12O31.9(OH)4.1 (with the OH content adjusted to achieve charge balance). Aside from the Na content, this composition is similar to that observed as wide-chain lamellae in host actinolite. The relative ease with which Na-rich triple chains can be made experimentally suggests that these phases might exist in nature; this study provides additional insights into the range of compositions and formation conditions at which they might occur.

New double molybdate Na9Fe(MoO4)6: Synthesis, structure, properties

NASA Astrophysics Data System (ADS)

Savina, Aleksandra A.; Solodovnikov, Sergey F.; Basovich, Olga M.; Solodovnikova, Zoya A.; Belov, Dmitry A.; Pokholok, Konstantin V.; Gudkova, Irina A.; Stefanovich, Sergey Yu.; Lazoryak, Bogdan I.; Khaikina, Elena G.

2013-09-01

A new double molybdate Na9Fe(MoO4)6 was synthesized using solid state reactions and studied with X-ray powder diffraction, second harmonic generation (SHG) technique, differential scanning calorimetry, X-ray fluorescence analysis, Mössbauer and dielectric impedance spectroscopy. Single crystals of Na9Fe(MoO4)6 were obtained and its structure was solved (the space group R3¯, a=14.8264(2), c=19.2402(3) Å, V=3662.79(9) Å3, Z=6, R=0.0132). The structure is related to that of sodium ion conductor II-Na3Fe2(AsO4)3. The basic structure units are polyhedral clusters composed of central FeО6 octahedron sharing edges with three Na(1)О6 octahedra. The clusters share common vertices with bridging МоО4 tetrahedra to form an open 3D framework where the cavities are occupied by Na(2) and Na(3) atoms. The compound melts incongruently at 904.7±0.2 K. Arrhenius type temperature dependence of electric conductivity σ has been registered in solid state (σ=6.8×10-2 S сm-1 at 800 K), thus allowing considering Na9Fe(MoO4)6 as a new sodium ion conductor.

Profound regulation of Na/K pump activity by transient elevations of cytoplasmic calcium in murine cardiac myocytes

PubMed Central

Lu, Fang-Min; Deisl, Christine; Hilgemann, Donald W

2016-01-01

Small changes of Na/K pump activity regulate internal Ca release in cardiac myocytes via Na/Ca exchange. We now show conversely that transient elevations of cytoplasmic Ca strongly regulate cardiac Na/K pumps. When cytoplasmic Na is submaximal, Na/K pump currents decay rapidly during extracellular K application and multiple results suggest that an inactivation mechanism is involved. Brief activation of Ca influx by reverse Na/Ca exchange enhances pump currents and attenuates current decay, while repeated Ca elevations suppress pump currents. Pump current enhancement reverses over 3 min, and results are similar in myocytes lacking the regulatory protein, phospholemman. Classical signaling mechanisms, including Ca-activated protein kinases and reactive oxygen, are evidently not involved. Electrogenic signals mediated by intramembrane movement of hydrophobic ions, such as hexyltriphenylphosphonium (C6TPP), increase and decrease in parallel with pump currents. Thus, transient Ca elevation and Na/K pump inactivation cause opposing sarcolemma changes that may affect diverse membrane processes. DOI: http://dx.doi.org/10.7554/eLife.19267.001 PMID:27627745

Effect of the CaO/SiO2 mass ratio and FeO content on the viscosity of CaO-SiO2-"FeO"-12wt%ZnO-3wt%Al2O3 slags

NASA Astrophysics Data System (ADS)

Lü, Jian-fang; Jin, Zhe-nan; Yang, Hong-ying; Tong, Lin-lin; Chen, Guo-bao; Xiao, Fa-xin

2017-07-01

An effective process for recycling lead from hazardous waste cathode ray tubes (CRTs) funnel glass through traditional lead smelting has been presented previously. The viscous behavior of the molten high lead slag, which is affected by the addition of funnel glass, plays a critical role in determining the production efficiency. Therefore, the viscosities of the CaO-SiO2-"FeO"-12wt%ZnO-3wt%Al2O3 slags were measured in the current study using the rotating spindle method. The slag viscosity decreases as the CaO/SiO2 mass ratio is increased from 0.8 to 1.2 and also as the FeO content is increased from 8wt% to 20wt%. The breaking temperature of the slag is lowered substantially by the addition of FeO, whereas the influence of the CaO/SiO2 mass ratio on the breaking temperature is complex. The structural analysis of quenched slags using Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy reveals that the silicate network structure is depolymerized with increasing CaO/SiO2 mass ratio or increasing FeO content. The [FeO6]-octahedra in the slag melt increase as the CaO/SiO2 mass ratio or the FeO content increases. This increase can further decrease the degree of polymerization (DOP) of the slag. Furthermore, the activation energy for viscous flow decreases both with increasing CaO/SiO2 mass ratio and increasing FeO content.

Comet C2012 S1 (ISON): Observations of the Dust Grains From SOFIA and of the Atomic Gas From NSO Dunn and Mcmath-Pierce Solar Telescopes

NASA Technical Reports Server (NTRS)

Wooden, Diane H.; Woodward, Charles E.; Harker, David E.; Kelley, Michael S. P.; Sitko, Michael; Reach, William T.; De Pater, Imke; Gehrz, Robert D.; Kolokolova, Ludmilla; Cochran, Anita L.;

The mechanism of potentiation of the glutamate-induced neurotoxicity by serum albumin. A possible role of nitric oxide.

PubMed

Sorokina, E G; Reutov, V P; Pinelis, V G; Vinskaya, N P; Vergun, O V; Khodorov, B I

2000-01-01

Potentiation of the delayed (Glu)-induced neurotoxicity by serum albumin (SA) was studied in experiments with cultured cerebellar granule cells. The delayed neuronal death (DND) was evaluated by counting neurons containing or excluding Trypan Blue 4 h after treatment with Glu. Cytoplasmic Ca2+ ([Ca2+]i) was measured in individual Fura-2-loaded neurons. It was shown that a 15-min application of bovine SA (4 mg/ml) together with Glu (100 microM, 10 microM glycine, Mg2+-free solution) enhanced DND in the culture 1.7 times (43.1+/-3.1%) with respect to the effect induced by Glu alone (24.6+/-0.6%). The bovine SA application did not change the dynamics of [Ca2+]i response during a short-term (1 min) and long-term (15 min) Glu-treatment. DND was prevented by simultaneous application of Glu and inhibitor of NO-synthase N omega-nitro-L-arginine methyl ester (L-NAME), 100 microM) (10.8+/-1.0%) as well as by the application of Glu with SA and L-NAME (9.8+/-1.2%). In order to evaluate the role of nitric oxide (NO) in the SA effect, the cells were incubated for 15 min with the NO-donors sodium nitroprusside (SNP, 10 and 100 microM) and sodium nitrite (NaNO2, 10 and 100 microM) together with SA and in its absence. SA also greatly enhanced the DND induced by SNP and NaNO2. Thus, the DND after simultaneous treatment with SA and SNP was 16.3+/-2.5% (10 microM) or 29.6+/-2.1% (100 microM), and 9.6+/-0.8% (10 microM) and 19.7+/-2.1% after treatment with SNP alone. Exposure to SA together with NaNO2 led to the DND increase up to 26.5+/-1.9% (10 microM) and 37.7+/-3.5% (100 microM) in comparison with 7.4+/-2.0% (10 microM) and 18.9+/-0.8% (100 microM) in experiments with NaNO2 alone. Taking into account the ability of NO and NO2 to oxidize unsaturated fatty acids and the ability of SA to bind them after their hydrolytic removal, we suggested that the SA-induced potentiation of Glu neurotoxicity resulted from exacerbation of the toxic effects of NO and other trace radicals on the neuronal membranes. This hypothesis was supported by the finding that SA also enhanced the neurotoxicity of the lipid prooxidant FeCl2. The simultaneous 15-min application of FeCl2 (10 microM) and SA caused a 51.5+/-4.0% increase in DND, which exceeded 2.4 times the effect produced by FeCl2 alone (21.3+/-2.3%).

Consumption of galacto-oligosaccharides increases iron absorption from a micronutrient powder containing ferrous fumarate and sodium iron EDTA: a stable-isotope study in Kenyan infants.

PubMed

Paganini, Daniela; Uyoga, Mary A; Cercamondi, Colin I; Moretti, Diego; Mwasi, Edith; Schwab, Clarissa; Bechtler, Salome; Mutuku, Francis M; Galetti, Valeria; Lacroix, Christophe; Karanja, Simon; Zimmermann, Michael B

2017-10-01

Background: Whether consumption of prebiotics increases iron absorption in infants is unclear. Objective: We set out to determine whether prebiotic consumption affects iron absorption from a micronutrient powder (MNP) containing a mixture of ferrous fumarate and sodium iron EDTA (FeFum+NaFeEDTA) in Kenyan infants. Design: Infants ( n = 50; aged 6-14 mo) consumed maize porridge that was fortified with an MNP containing FeFum+NaFeEDTA and 7.5 g galacto-oligosaccharides (GOSs) (Fe+GOS group, n = 22) or the same MNP without GOSs (Fe group, n = 28) each day for 3 wk. Then, on 2 consecutive days, we fed all infants isotopically labeled maize porridge and MNP test meals containing 5 mg Fe as 57 FeFum+Na 58 FeEDTA or ferrous sulfate ( 54 FeSO 4 ). Iron absorption was measured as the erythrocyte incorporation of stable isotopes. Iron markers, fecal pH, and bacterial groups were assessed at baseline and 3 wk. Comparisons within and between groups were done with the use of mixed-effects models. Results: There was a significant group-by-compound interaction on iron absorption ( P = 0.011). The median percentages of fractional iron absorption from FeFum+NaFeEDTA and from FeSO 4 in the Fe group were 11.6% (IQR: 6.9-19.9%) and 20.3% (IQR: 14.2-25.7%), respectively, ( P < 0.001) and, in the Fe+GOS group, were 18.8% (IQR: 8.3-37.5%) and 25.5% (IQR: 15.1-37.8%), respectively ( P = 0.124). Between groups, iron absorption was greater from the FeFum+NaFeEDTA ( P = 0.047) in the Fe+GOS group but not from the FeSO 4 ( P = 0.653). The relative iron bioavailability from FeFum+NaFeEDTA compared with FeSO 4 was higher in the Fe+GOS group than in the Fe group (88% compared with 63%; P = 0.006). There was a significant time-by-group interaction on Bifidobacterium spp. ( P = 0.008) and Lactobacillus / Pediococcus / Leuconostoc spp. ( P = 0.018); Lactobacillus / Pediococcus / Leuconostoc spp. decreased in the Fe group ( P = 0.013), and there was a nonsignificant trend toward higher Bifidobacterium spp. in the Fe+GOS group ( P = 0.099). At 3 wk, iron absorption was negatively correlated with fecal pH ( P < 0.001) and positively correlated with Lactobacillus / Pediococcus / Leuconostoc spp. ( P = 0.001). Conclusion: GOS consumption by infants increased iron absorption by 62% from an MNP containing FeFum+NaFeEDTA, thereby possibly reflecting greater colonic iron absorption. This trial was registered at clinicaltrials.gov as NCT02666417. © 2017 American Society for Nutrition.

Overview Of 100 Sols Of Chemcam Operations At Gale Crater

NASA Astrophysics Data System (ADS)

Maurice, Sylvestre; Wiens, Roger; MSL Science Team

2013-04-01

The Curiosity rover carries the ChemCam instrument suite, a Laser-Induced Breakdown Spectroscopy (LIBS) instrument that can analyze the chemical composition of geological samples at distances up to 7 meters from the rover, and a high resolution camera for context imaging (RMI). In the first 100 sols after landing, ChemCam performed 343 single point measurements on approximately 50 different rocks or soil areas, for over 12,000 laser shots. Each time at least two RMI images are acquired before and after the laser shots to visualize the area of investigation and the geological context. LIBS lines are identified using primarily a martian dedicated database; to date, ChemCam has detected unambiguously major elements (Si, Al, Fe, Mg, Ca, Na, K, O), minor/trace elements of interest (Li, Cr, Mn, Rb, Sr, Ba, Ti, S, C, H). These observations allow a qualitative/quantitative assessment of the presence of dust (first few shots), the sample surface composition and chemical heterogeneity with depth. Several techniques have been developed to analyze ChemCam's data: (1) Univariate analysis refers to peak height studies of well-chosen LIBS lines and a training dataset to build calibration curves. Peak ratios K/Si, Na/Si, Al/Si, Fe+Mg/Si, or Mg/Mg+Fe have been calculated from the onboard calibration targets. The technique also applies to minor and trace elements which yield low intensity emission lines, such as Lin, Rb, H, C. (2) Multivariate methods give better results in terms of elemental composition, since they examine simultaneously and statistically several peaks of the same elements. A Partial Least Squares (PLS) regression algorithm is used for rapid major-element abundance determination. (3) Composition trends, clusters and end-members can also be identified using component analysis methods. Independent Component Analysis (ICA) identifies components that are directly related to Chemical elements: Al, Ca, Fe, H, K, Mg, Na, O, Si, Ti, but also mixture like a "soil" component. On top of this classification, clustering methods such as k-means and hierarchical clustering allow the differentiation and filation of different geochemical populations encountered so far at Mars. The ChemCam instruments are performing very well. The 100-sol dataset is rich of thousands of spectra and hundreds of images. We will present a status of the data set acquired during that period, a review of the analysis techniques and an introduction to the results which have been obtained so far.

Comparison of clinical characteristics among narcolepsy with and without cataplexy and idiopathic hypersomnia without long sleep time, focusing on HLA-DRB1( *)1501/DQB1( *)0602 finding.

PubMed

Sasai, Taeko; Inoue, Yuichi; Komada, Yoko; Sugiura, Tatsuki; Matsushima, Eisuke

2009-10-01

Clinical characteristics of narcolepsy without cataplexy (NA w/o CA) and its relation to positivity of HLA-DRB1( *)1501/DQB1( *)0602 remain unclarified. We investigated clinical features of NA w/o CA, particularly addressing HLA-DRB1( *)1501/DQB1( *)0602. Comparisons of the Epworth Sleepiness Scale (ESS), multiple sleep latency test (MSLT) variables, rapid eye movement (REM)-related symptoms, and treatment response to psychostimulant medication were made for four patient groups (narcolepsy with cataplexy; NA-CA, NA w/o CA HLA-positive, NA w/o CA HLA-negative, and idiopathic hypersomnia without long sleep time; IHS w/o LST). Mean sleep latency was significantly shorter and the rate of reduction of ESS after medication was lower in both NA-CA and NA w/o CA HLA-positive groups than those in the IHS w/o LST group. Among the three narcoleptic groups, the NA w/o CA HLA-negative group showed the lowest REM latency and the highest reduction rate of ESS after treatment. Neither these subjective and objective sleepiness measures nor the treatment response measure was significantly different between this group and the IHS w/o LST group. In NA w/o CA, HLA-positivity might affect hypersomnia severity and REM propensity. The NA w/o CA HLA-negative group and the IHS w/o LST group exhibit equivalent hypersomnia severity.

Characteristics of anthropogenic magnetic materials in roadside dusts in Seoul, Korea using thermo-magnetic behaviors and electron microscope observations

NASA Astrophysics Data System (ADS)

Kim, W.; Doh, S.; Park, Y.

2006-12-01

It has been previously reported that magnetic concentration parameter (e.g., magnetic susceptibility) has a close affinity with heavy metal concentration in roadside dust of the Seoul metropolitan area. Magnetic concentration and magnetic particle size show systematic seasonal fluctuations (high and large during winter; low and small in summer) because of seasonal influx variation of anthropogenic magnetic materials. These observations suggest that magnetic parameters could be utilized as a proxy method of assessing heavy metal pollution in urban areas. In order to characterize anthropogenic magnetic materials and to find their potential sources, magnetic extracts from roadside dusts of Seoul metropolitan area were subject to SEM observation, elemental analysis (EDS), and thermo-magnetic experiments. Magnetic materials from vehicle emission and abraded brake lining were also observed for the comparison. The magnetic particles can be classified based on the morphology and elemental composition of the particles. Magnetic spherules are the most frequently observed type of particle throughout the study area. These particles are often associated with the elemental C and Al-Ca-Na-Si materials, and are believed to be the product of fossil fuel combustions in power plants, industries, and domestic heating systems. Aggregates of iron-oxides and Fe-C-S materials are probably originated from vehicle emission, while aggregates of pure Fe and Al-Ca-Fe-K-Mg-Si materials appear to be derived from abrasion of motor vehicle brake system. These aggregates are frequently observed in industrial sections of the city as well as areas of heavy traffic. Angular magnetic particles accompanied by silicates are only observed in park area and probably formed by natural process such as pedogenesis or weathering. Thermo-magnetic experiments indicate that the major magnetic phase in the studied samples is magnetite. Two distinctive behaviors observed are the presence of low Curie temperature magnetic phase and under- recover of susceptibility on cooling. It is considered that Fe-C-S magnetic aggregates possibly behaved like pyrrhotite, and thus recognized as low Curie temperature magnetic phase. A factor causing under-recover of susceptibility is attributed to some of magnetic spherules associated with C and Al-Ca-Na-Si materials which possibly behaved like iron-oxide containing impurities. Overall, this study shows that the magnetic methods in conjunction with SEM observations and elemental analyses for urban roadside dust can be used as a powerful tool for assessment of pollution features in an urban area in terms of source and spatial distribution of anthropogenic magnetic materials and associated heavy metals.

Renal hypertension prevents run training modification of cardiomyocyte diastolic Ca2+ regulation in male rats.

PubMed

Palmer, B M; Lynch, J M; Snyder, S M; Moore, R L

2001-06-01

The combined effects of endurance run training and renal hypertension on cytosolic Ca2+ concentration ([Ca2+]c) dynamics and Na+-dependent Ca2+ regulation in rat left ventricular cardiomyocytes were examined. Male Fischer 344 rats underwent stenosis of the left renal artery [hypertensive (Ht), n = 18] or a sham operation [normotensive (Nt), n = 20]. One-half of the rats from each group were treadmill trained for >16 wk. Cardiomyocyte fura 2 fluorescence ratio transients were recorded for 7 min during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degrees C. The rate of [Ca2+]c decline was not changed by run training in the Nt group but was reduced in the Ht group. At 7 min, cardiomyocytes were exposed to 10 mM caffeine in the absence of Na+ and Ca2+, which triggered sarcoplasmic reticular Ca2+ release and suppressed Ca2+ efflux via Na+/Ca2+ exchanger. External Na+ was then added, and Na+-dependent Ca2+ efflux rate was recorded. Treadmill training significantly enhanced Na+-dependent Ca2+ efflux rate under these conditions in the Nt group but not in the Ht group. These data provide evidence that renal hypertension prevents the normal run training-induced modifications in diastolic [Ca2+]c regulation mechanisms, including Na+/Ca2+ exchanger.