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Sample records for related divalent metal

  1. Dispersion relations of the acoustic modes in divalent liquid metals

    Directory of Open Access Journals (Sweden)

    Inui Masanori

    2017-01-01

    Full Text Available Collective dynamics in liquid Ca and liquid Cd was studied by inelastic x-ray scattering (IXS. Using our experimental technique to prepare proper sample cells and high performance of an IXS beamline (BL35XU at SPring-8 in Japan, the dynamic structure factor with reasonable statistics was obtained for these divalent liquid metals. For both liquids, the dynamic structure factor at low Q exhibits a central peak with a shoulder or small hump clearly visible on each side, and the inelastic excitation energy determined using the model function composed of Lorentzian and the damped harmonic oscillator function disperses with increasing Q. The dispersion curves of these liquids were compared with that of the longitudinal acoustic phonon in each crystalline phase. From these results, clear difference in the interatomic interaction be- tween liquid Ca and liquid Cd was inferred.

  2. Aging of trivalent metal hydroxide/oxide gels in divalent metal salt ...

    Indian Academy of Sciences (India)

    Unknown

    3' gels do not form LDHs on aging in any of the divalent metal salts. In general, conditions .... values of I pH and II pH for all the systems investigated in this paper are given in ... spectra were obtained using a Nicolet Model Impact. 400D FTIR ...

  3. Influence of divalent metal ions on degradation of dimethylsulphide ...

    African Journals Online (AJOL)

    SERVER

    2007-06-04

    Jun 4, 2007 ... Dimethylsulphide degradation by intact cells of Thiobacillus thioparus TK-m was stimulated by the addition of divalent .... plastic vials in ice-cooled water. .... tization of authotrophic sulphur bacteria oxidizing dimethyldisulphide.

  4. A computational study of adsorption of divalent metal ions on graphene oxide

    Directory of Open Access Journals (Sweden)

    Somphob Thompho

    2017-12-01

    Full Text Available Adsorption of divalent metal ions (Pb2+,Cd2+, Zn2+,Cu2+ on graphene oxide (GO was studied using density functional theory (DFT. Adsorption geometries and energies, as well as the nature of the binding energy, were calculated for the interaction of divalent metal ions with oxygen-containing groups on the surface of GO. The configurations of the complexes were modeled by placing the divalent metal ions above the center and perpendicular to the surface. Binding of Cu2+ to the GO sheet was predicted to be much stronger than that for other divalent metal ions. Calculated results show good agreement with experimental observations and provide useful information for environmental pollution cleanup.

  5. Divalent Metal Ions Induced Osteogenic Differentiation of MC3T3E1

    Science.gov (United States)

    Wang, Guoshou; Su, Wenta; Chen, Pohung; Huang, Teyang

    2017-12-01

    Biomaterial scaffolds blended with biochemical signal molecules with adequate osteoinductive and osteoconductive properties have attracted significant interest in bone tissue engineering regeneration. The divalent metal ions can gradually release from the scaffold into the culture medium and then induced osteoblastic differentiation of MC3T3E1. These MC3T3E1 cells expressed high activity of alkaline phosphatase, bone-related gene expression of collagen type I, Runx2, osteopontin, osteocalcin, and significantly enhanced deposited minerals on scaffold after 21 days of culture. This experiment provided a useful inducer for osteogenic differentiation in bone repair.

  6. Interactions of chlorphenesin and divalent metal ions with phosphodiesterase.

    Science.gov (United States)

    Edelson, J; McMullen, J P

    1976-09-01

    Chlorphenesin inhibition of the hydrolysis of cyclic AMP by guinea-pig lung phosphodiesterase was reversed by the addition of exogenous magnesium ions. Chlorphenesin and theophylline inhibition of this enzyme was shown to be noncompetitive when the substrate concentration was low. Kinetic studies of the inhibition of beef heart phosphodiesterase by chlorphenesin and theophylline indicated that the substrate concentration was a factor in determining whether inhibition was competitive or noncompetitive. Calcium, cobalt and copper ions were inhibitory to guinea-pig lung phosphodiesterase. The inhibition due to chlorphenesin was partially reversed by low (40 mM or less) concentrations of barium ions; high concentrations of barium ions, or manganese ions, were inhibitory. The concentration of the divalent cation did not affect the type of inhibition that was observed.

  7. Divalent metal ion removal from aqueous solution by acid-treated ...

    African Journals Online (AJOL)

    ions determined from the Langmuir isotherm showed that C. indica had the largest sorption capacity for Pb2+ ions and the least sorption for Ni2+. The results also showed that garlic-treatment of C. indica biomass enhanced its sorption capacity for the divalent metal ions, with the enhancement factor varying from 1.22 to 1.44 ...

  8. Response of a benzoxainone derivative linked to monoaza-15-crown-5 with divalent heavy metals.

    Science.gov (United States)

    Addleman, R S; Bennett, J; Tweedy, S H; Elshani, S; Wai, C M

    1998-08-01

    The response of a monoaza-15-crown-5 with an optically active aminobenzoxazinone moiety to divalent cations was investigated. The crown ether was found to undergo a strong emission shift to the blue when complexed with specific divalent metals that have ionic diameters between 1.9-2.4 A. Consequently the photoactive macrocycle is responsive to Mg(2+), Ca(2+), Ba(2+), Sr(2+), Cd(2+), and particularly responsive to Hg(2+)and Pb(2+). Macrocycle emission spectra are shown to be a function of cation concentration. Alkaline metal cations and smaller transition metals ions such as Ni(2+), Co(2+)and Zn(2+)do not cause significant changes in the macrocycle emission spectra. Emission, absorption, and complex stability constants are determined. Mechanisms of cation selectivity and spectral emission shifts are discussed. Challenges involving immobilization of the macrocycle while preserving its spectral response to cations are explored.

  9. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Science.gov (United States)

    Moore, Robert C; Holt-Larese, Kathleen C; Bontchev, Ranko

    2013-08-13

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  10. Use of MgO doped with a divalent or trivalent metal cation for removing arsenic from water

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C.; Larese, Kathleen Caroline; Bontchev, Ranko Panayotov

    2017-05-30

    Systems and methods for use of magnesium hydroxide, either directly or through one or more precursors, doped with a divalent or trivalent metal cation, for removing arsenic from drinking water, including water distribution systems. In one embodiment, magnesium hydroxide, Mg(OH).sub.2 (a strong adsorbent for arsenic) doped with a divalent or trivalent metal cation is used to adsorb arsenic. The complex consisting of arsenic adsorbed on Mg(OH).sub.2 doped with a divalent or trivalent metal cation is subsequently removed from the water by conventional means, including filtration, settling, skimming, vortexing, centrifugation, magnetic separation, or other well-known separation systems. In another embodiment, magnesium oxide, MgO, is employed, which reacts with water to form Mg(OH).sub.2. The resulting Mg(OH).sub.2 doped with a divalent or trivalent metal cation, then adsorbs arsenic, as set forth above. The method can also be used to treat human or animal poisoning with arsenic.

  11. Synergistic extraction of some divalent metal cations into nitrobenzene by using strontium dicarbollylcobaltate and electroneutral macrocyclic lactam receptor

    Czech Academy of Sciences Publication Activity Database

    Makrlík, E.; Sedláková, Zdeňka; Vaňura, P.; Selucký, P.

    2013-01-01

    Roč. 295, č. 3 (2013), s. 2263-2266 ISSN 0236-5731 Institutional support: RVO:61389013 Keywords : divalent metal cations * macrocyclic lactam receptor * complexation Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.415, year: 2013

  12. Two Divalent Metal Ions and Conformational Changes Play Roles in the Hammerhead Ribozyme Cleavage Reaction

    Science.gov (United States)

    Mir, Aamir; Chen, Ji; Robinson, Kyle; Lendy, Emma; Goodman, Jaclyn; Neau, David; Golden, Barbara L.

    2016-01-01

    The hammerhead ribozyme is a self-cleaving RNA broadly dispersed across all kingdoms of life. Although it was the first of the small, nucleolytic ribozymes discovered, the mechanism by which it catalyzes its reaction remains elusive. The nucleobase of G12 is well positioned to be a general base, but it is unclear if or how this guanine base becomes activated for proton transfer. Metal ions have been implicated in the chemical mechanism, but no interactions between divalent metal ions and the cleavage site have been observed crystallographically. To better understand how this ribozyme functions, we have solved crystal structures of wild-type and G12A mutant ribozymes. We observe a pH-dependent conformational change centered around G12, consistent with this nucleotide becoming deprotonated. Crystallographic and kinetic analysis of the G12A mutant reveals a Zn2+ specificity switch suggesting a direct interaction between a divalent metal ion and the purine at position 12. The metal ion specificity switch and the pH–rate profile of the G12A mutant suggest that the minor imino tautomer of A12 serves as the general base in the mutant ribozyme. We propose a model in which the hammerhead ribozyme rearranges prior to the cleavage reaction, positioning two divalent metal ions in the process. The first metal ion, positioned near G12, becomes directly coordinated to the O6 keto oxygen, to lower the pKa of the general base and organize the active site. The second metal ion, positioned near G10.1, bridges the N7 of G10.1 and the scissile phosphate and may participate directly in the cleavage reaction. PMID:26398724

  13. Determination of the nitrogen vacancy as a shallow compensating center in GaN doped with divalent metals.

    Science.gov (United States)

    Buckeridge, J; Catlow, C R A; Scanlon, D O; Keal, T W; Sherwood, P; Miskufova, M; Walsh, A; Woodley, S M; Sokol, A A

    2015-01-09

    We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-defined reference level. Defect formation and ionization energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p-type conductivity in GaN and the associated major spectroscopic features, including the ubiquitous 3.46 eV photoluminescence line, a characteristic of all lightly divalent-metal-doped GaN materials that has also been shown to occur in pure GaN samples. Our results give a comprehensive explanation for the observed behavior of GaN doped with low concentrations of divalent metals in good agreement with relevant experiment.

  14. Determination of the Nitrogen Vacancy as a Shallow Compensating Center in GaN Doped with Divalent Metals

    Science.gov (United States)

    Buckeridge, J.; Catlow, C. R. A.; Scanlon, D. O.; Keal, T. W.; Sherwood, P.; Miskufova, M.; Walsh, A.; Woodley, S. M.; Sokol, A. A.

    2015-01-01

    We report accurate energetics of defects introduced in GaN on doping with divalent metals, focusing on the technologically important case of Mg doping, using a model that takes into consideration both the effect of hole localization and dipolar polarization of the host material, and includes a well-defined reference level. Defect formation and ionization energies show that divalent dopants are counterbalanced in GaN by nitrogen vacancies and not by holes, which explains both the difficulty in achieving p -type conductivity in GaN and the associated major spectroscopic features, including the ubiquitous 3.46 eV photoluminescence line, a characteristic of all lightly divalent-metal-doped GaN materials that has also been shown to occur in pure GaN samples. Our results give a comprehensive explanation for the observed behavior of GaN doped with low concentrations of divalent metals in good agreement with relevant experiment.

  15. Toxic and biochemical effects of divalent metal ions in Drosophila: correlation to effects in mice and to chemical softness parameters

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, K B; Turner, J E; Christie, N T; Owenby, R K

    1983-01-01

    The mechanism of toxicity of 11 divalent cations was evaluated by determining the effects of dietary administration to Drosophila melanogaster and measurement of the frequency of lethality at 4 days, alterations in the developmental patterns of proteins, and changes in specific transfer RNAs. The relative effectiveness of divalent cations to kill Drosophila is significantly correlated to the relative values of the coordinate bond energy of the metal ions. The resistance of Drosophila to cadmium toxicity appears to be genetically determined since different inbred strains vary markedly. Also, the resistance is maximal in the young adult. Two different genetic strains seem to respond to different cations (Cd/sup 2 +/, Hg/sup 2 +/, Cu/sup 2 +/, Co/sup 2 +/, Ba/sup 2 +/, and Sr/sup 2 +/) in a similar manner. Basic mechanisms of toxicity may be studied in Drosophila as well as mice since the chemical properties of the metals reflect their toxic effects on the former as closely as the latter. 25 references, 5 figures, 1 table.

  16. Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

    Science.gov (United States)

    Yadav, Sushma; Chandra, Amalendu

    2017-12-01

    We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion pairing, and dynamics of water in the solvation shells and also of ion diffusion in aqueous solutions of divalent metal nitrate salts.

  17. Drosophila divalent metal ion transporter Malvolio is required in dopaminergic neurons for feeding decisions.

    Science.gov (United States)

    Søvik, E; LaMora, A; Seehra, G; Barron, A B; Duncan, J G; Ben-Shahar, Y

    2017-06-01

    Members of the natural resistance-associated macrophage protein (NRAMP) family are evolutionarily conserved metal ion transporters that play an essential role in regulating intracellular divalent cation homeostasis in both prokaryotes and eukaryotes. Malvolio (Mvl), the sole NRAMP family member in insects, plays a role in food choice behaviors in Drosophila and other species. However, the specific physiological and cellular processes that require the action of Mvl for appropriate feeding decisions remain elusive. Here, we show that normal food choice requires Mvl function specifically in the dopaminergic system, and can be rescued by supplementing food with manganese. Collectively, our data indicate that the action of the Mvl transporter affects food choice behavior via the regulation of dopaminergic innervation of the mushroom bodies, a principle brain region associated with decision-making in insects. Our studies suggest that the homeostatic regulation of the intraneuronal levels of divalent cations plays an important role in the development and function of the dopaminergic system and associated behaviors. © 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  18. Interaction of divalent metal ions with Zn(2+)-glycerophosphocholine cholinephosphodiesterase from ox brain.

    Science.gov (United States)

    Lee, K J; Kim, M R; Kim, Y B; Myung, P K; Sok, D E

    1997-12-01

    The effect of divalent metal ions on the activity of glycerophosphocholine cholinephosphodiesterse from ox brain was examined. Zn(2+)- and Co(2+)-glycerophosphocholine cholinephosphodiesterases were prepared from the exposure of apoenzyme to Zn2+ and Co2+, respectively, and the properties of two metallo-phosphodiesterases were compared to those of native phosphodiesterase. Although two metallo-enzymes were similar in expressing Km value, optimum pH or sensitivity to Cu2+, they differed in the susceptibility to the inhibition by thiocholine or tellurite; while Co(2+)-phosphodiesterase was more sensitive to tellurites, Zn(2+)-phosphodiesterase was more susceptible to inhibition by thiocholine. In addition, Zn(2+)-phosphodiesterase was more thermo-stable than Co2+ enzyme. Separately, when properties of native phosphodiesterase were compared to those of each metallo-phosphodiesterase, native phosphodiesterase was found to be quite similar to Zn(2+)-phosphodiesterase in many respects. Even in thermo-stability, native enzyme resembled Zn(2+)-phosphodiesterase rather than Co(2+)-enzyme. Consistent with this, the stability of native phosphodiesterase was maintained in the presence of Zn2+, but not Co2+, Mn2+ was also as effective as Zn2+ in the stabilization of the enzyme. Noteworthy, the native enzyme was found to be inhibited competitively by Cu2+ with a Ki value of 20 microM, and its inhibitory action was antagonized effectively by Zn2+ or Co2+. Also, choline, another competitive inhibitor of the enzyme, appeared to antagonize the inhibitory action of Cu2+. Taken together, it is suggested that there may be multiple binding sites for divalent metal ions in the molecule of glycerophosphocholine cholinephosphodiesterase.

  19. Optical study of gamma irradiated sodium metaphosphate glasses containing divalent metal oxide MO (ZnO or CdO

    Directory of Open Access Journals (Sweden)

    E. Nabhan

    Full Text Available Sodium metaphosphate glasses containing divalent metal oxide, ZnO or CdO with composition 50 P2O5 – (50 − x Na2O – x MO (ZnO, or CdO where x = 0, 10, 20 (mol% were prepared by conventional melt method. UV/visible spectroscopy and FTIR spectroscopy are measured before and after exposing to successive gamma irradiation doses (5–80 kGy. The optical absorption spectra results of the samples before irradiation reveal a strong UV absorption band at (∼230 nm which is related to unavoided iron impurities. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. From the optical absorption spectral data, the optical band gap is evaluated. The main structural groups and the influence of both divalent metal oxide and gamma irradiation effect on the structural vibrational groups are realized through IR spectroscopy. The FTIR spectra of γ-irradiated samples are characterized by the stability of the number and position for the main characteristic band of phosphate groups. To better understood the structural changes during γ-irradiation, a deconvolution of FTIR spectra in the range 650–1450 cm−1 is made. The FTIR deconvolution results found evidence that, the changes occurring after gamma irradiation have been related to irradiation induced structural defects and compositional changes. Keywords: Sodium metaphosphate glass, UV–visible spectra, IR spectra, Deconvolution, Optical band gap, Gamma ray

  20. Divalent metal ion differentially regulates the sequential nicking reactions of the GIY-YIG homing endonuclease I-BmoI.

    Directory of Open Access Journals (Sweden)

    Benjamin P Kleinstiver

    Full Text Available Homing endonucleases are site-specific DNA endonucleases that function as mobile genetic elements by introducing double-strand breaks or nicks at defined locations. Of the major families of homing endonucleases, the modular GIY-YIG endonucleases are least understood in terms of mechanism. The GIY-YIG homing endonuclease I-BmoI generates a double-strand break by sequential nicking reactions during which the single active site of the GIY-YIG nuclease domain must undergo a substantial reorganization. Here, we show that divalent metal ion plays a significant role in regulating the two independent nicking reactions by I-BmoI. Rate constant determination for each nicking reaction revealed that limiting divalent metal ion has a greater impact on the second strand than the first strand nicking reaction. We also show that substrate mutations within the I-BmoI cleavage site can modulate the first strand nicking reaction over a 314-fold range. Additionally, in-gel DNA footprinting with mutant substrates and modeling of an I-BmoI-substrate complex suggest that amino acid contacts to a critical GC-2 base pair are required to induce a bottom-strand distortion that likely directs conformational changes for reaction progress. Collectively, our data implies mechanistic roles for divalent metal ion and substrate bases, suggesting that divalent metal ion facilitates the re-positioning of the GIY-YIG nuclease domain between sequential nicking reactions.

  1. Influence of commercial (Fluka) naphthenic acids on acid volatile sulfide (AVS) production and divalent metal precipitation.

    Science.gov (United States)

    McQueen, Andrew D; Kinley, Ciera M; Rodgers, John H; Friesen, Vanessa; Bergsveinson, Jordyn; Haakensen, Monique C

    2016-12-01

    Energy-derived waters containing naphthenic acids (NAs) are complex mixtures often comprising a suite of potentially problematic constituents (e.g. organics, metals, and metalloids) that need treatment prior to beneficial use, including release to receiving aquatic systems. It has previously been suggested that NAs can have biostatic or biocidal properties that could inhibit microbially driven processes (e.g. dissimilatory sulfate reduction) used to transfer or transform metals in passive treatment systems (i.e. constructed wetlands). The overall objective of this study was to measure the effects of a commercially available (Fluka) NA on sulfate-reducing bacteria (SRB), production of sulfides (as acid-volatile sulfides [AVS]), and precipitation of divalent metals (i.e. Cu, Ni, Zn). These endpoints were assessed following 21-d aqueous exposures of NAs using bench-scale reactors. After 21-days, AVS molar concentrations were not statistically different (pAVS production was sufficient in all NA treatments to achieve ∑SEM:AVS AVS) could be used to treat metals occurring in NAs affected waters. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Adsorption preference for divalent metal ions by Lactobacillus casei JCM1134.

    Science.gov (United States)

    Endo, Rin; Aoyagi, Hideki

    2018-05-09

    The removal of harmful metals from the intestinal environment can be inhibited by various ions which can interfere with the adsorption of target metal ions. Therefore, it is important to understand the ion selectivity and adsorption mechanism of the adsorbent. In this study, we estimated the adsorption properties of Lactobacillus casei JCM1134 by analyzing the correlation between its maximum adsorption level (q max ) for seven metals and their ion characteristics. Some metal ions showed altered adsorption levels by L. casei JCM1134 as culture growth time increased. Although it was impossible to identify specific adsorption components, adsorption of Sr and Ba may depend on capsular polysaccharide levels. The maximum adsorption of L. casei JCM1134 (9 h of growth in culture) for divalent metal ions was in the following order: Cu 2+  > Ba 2+  > Sr 2+  > Cd 2+  > Co 2+  > Mg 2+  > Ni 2+ . The q max showed a high positive correlation with the ionic radius. Because this tendency is similar to adsorption occurring through an ion exchange mechanism, it was inferred that an ion exchange mechanism contributed greatly to adsorption by L. casei JCM1134. Because the decrease in the amount of adsorption due to prolonged culture time was remarkable for metals with a large ion radius, it is likely that the adsorption components involved in the ion exchange mechanism decomposed over time. These results and analytical concept may be helpful for designing means to remove harmful metals from the intestinal tract.

  3. New 14-membered octaazamacrocyclic complexes of divalent transition metal ions with their antimicrobial and spectral studies

    Science.gov (United States)

    Singh, D. P.; Kumar, Krishan; Sharma, Chetan

    2010-01-01

    A novel series of macrocyclic complexes of the type [M(C 18H 14N 10S 2)X 2]; where M = Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); X = Cl -, NO 3-, CH 3COO - has been synthesized by [2+2] condensation of thiocarbohydrazide and isatin in the presence of divalent metal salts in methanolic medium. The complexes have been characterized with the help of elemental analyses, conductance measurements, magnetic measurements, electronic, NMR and infrared spectral studies. The low value of molar conductance indicates them to be non-electrolytes. On the basis of various studies a distorted octahedral geometry may be proposed for all of these complexes. These metal complexes were also tested for their in vitro antimicrobial activities against some Gram-positive bacteria viz. Staphylococcus aureus, Bacillus subtilis, and some Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and some fungal strains Aspergillus niger, Aspergillus flavus (molds), Candida albicans, Saccharomyces cerevisiae (yeasts). The results obtained were compared with standard antibiotic: Ciprofloxacin and the standard antifungal drug: Amphotericin-B.

  4. Studies on the competitive sorption of divalent metal ions to natural soil samples using a multitracer technique

    International Nuclear Information System (INIS)

    Fujiyoshi, R.; Hirashima, H.; Sawamura, S.

    1997-01-01

    Speciation of minor or trace amount of pollutants, such as heavy metals and radionuclides released from atmospheric precipitation and water streams have been studied in order to elucidate their fates in the environment through 'in situ' observations or laboratory experiments. The authors have investigated sorption of heavy metals on various natural samples radiometrically ( 65 Zn as a tracer). A sequential extraction technique was found to be very effective to elucidate possible scavengers (minerals) of heavy metals in some cases. A sediment with low CEC does not sorb Zn (ii) ions to a great extent. It is thus considered that the zinc sorption occurs competitively with protons present in the aqueous media. Divalent copper and cadmium ions also behaved similarly to Zn(II), which was obtained electrochemically with the ion selective electrodes of Cu(II) and Cd(II). This time the authors investigated the competitive sorption of Mn(ii) and Zn(II) to natural soils using a radiotracer technique, which was considered to be useful to evaluate relative importance of the sorption of each metal ion without serious matrix effects. Quite different properties appeared among those metal ions used independently or simultaneously as a tracer. Proton exchange process may be important for the Zn(II) sorption, whereas a solid-solution partition is supposed to control the Mn(ii) uptake, when each of them was examined independently as a sorbate. In contrast, simultaneous use of those tracers to a soil suspension had great effects on the result; the maximum sorption (A m ) of Zn(II) increased, and Mn(II) behaved like a sorbate which tends to occupy specific sites of the soil surfaces. Those results indicate that the sorption of minor and/or trace elements to natural soils would not be evaluated through a series of experiments with a single sorbate

  5. Solid-State Properties of One-Dimensional Metals Based on bis(oxalato)platinate Anions with Divalent Cations

    DEFF Research Database (Denmark)

    Braude, A.; Carneiro, K.; Jacobsen, Claus Schelde

    1987-01-01

    The crystal structures, superstructures, dc conductivity, optical properties, and thermopower of six linear-chain conductors of the type M0.8[Pt(C2O4)2]⋅(M=Ni,Co,Zn,Fe,Mg,Mn), where M is a divalent metal (M=Ni,Co,Zn,Fe,Mg,Mn), have been studied. At high temperatures they form a common orthorhombi...

  6. Mutational analysis of divalent metal ion binding in the active site of class II α-mannosidase from sulfolobus solfataricus

    DEFF Research Database (Denmark)

    Hansen, Dennis K.; Webb, Helen; Nielsen, Jonas Willum

    2015-01-01

    Mutational analysis of Sulfolobus solfataricus class II α-mannosidase was focused on side chains that interact with the hydroxyls of the-1 mannosyl of the substrate (Asp-534) or form ligands to the active site divalent metal ion (His-228 and His-533) judged from crystal structures of homologous e......, although less dramatically with some activating metal ions. No major differences in the pH dependence between wild-type and mutant enzymes were found in the presence of different metal ions. The pH optimum was 5, but enzyme instability was observed at pH...

  7. Spectroscopic and structural studies on some divalent metal salt of p-aminobenzoic acid (ABA(MG)) tetracyanonickelate complexes

    International Nuclear Information System (INIS)

    Atalay, Y.

    2004-01-01

    Infrared spectra of MLNi (CN) 4 [ M=Mn, Fe, Co, Ni, Zn or Cd and LDivalent metal salt of p- Aminobenzoic Acid or ABA (Mg) ] are reported. Their structure consists of polymeric layers of [M-Ni(CN) 4 ] α with the divalent metal salt of p-aminobenzoic acid [ABA(Mg)] molecules bound directly to the metal (M). These spectra were comparewith powder the Xray diffraction pattern of complexes. It is show that proposed structures for these complexes derived from Mattson 1000 FTIR spectra are consistent with the X-ray powder diffraction measurements and elemental analysis result

  8. Divalent metal (Ca, Cd, Mn, Zn) uptake and interactions in the aquatic insect Hydropsyche sparna.

    Science.gov (United States)

    Poteat, Monica D; Díaz-Jaramillo, Mauricio; Buchwalter, David B

    2012-05-01

    Despite their ecological importance and prevalent use as ecological indicators, the trace element physiology of aquatic insects remains poorly studied. Understanding divalent metal transport processes at the water-insect interface is important because these metals may be essential (e.g. Ca), essential and potentially toxic (e.g. Zn) or non-essential and toxic (e.g. Cd). We measured accumulation kinetics of Zn and Cd across dissolved concentrations ranging 4 orders of magnitude and examined interactions with Ca and Mn in the caddisfly Hydropsyche sparna. Here, we provide evidence for at least two transport systems for both Zn and Cd, the first of which operates at concentrations below 0.8 μmol l(-1) (and is fully saturable for Zn). We observed no signs of saturation of a second lower affinity transport system at concentrations up to 8.9 μmol l(-1) Cd and 15.3 μmol l(-1) Zn. In competition studies at 0.6 μmol l(-1) Zn and Cd, the presence of Cd slowed Zn accumulation by 35% while Cd was unaffected by Zn. At extreme concentrations (listed above), Cd accumulation was unaffected by the presence of Zn whereas Zn accumulation rates were reduced by 58%. Increasing Ca from 31.1 μmol l(-1) to 1.35 mmol l(-1) resulted in only modest decreases in Cd and Zn uptake. Mn decreased adsorption of Cd and Zn to the integument but not internalization. The L-type Ca(2+) channel blockers verapamil and nifedipine and the plasma membrane Ca(2+)-ATPase inhibitor carboxyeosin had no influence on Ca, Cd or Zn accumulation rates, while Ruthenium Red, a Ca(2+)-ATPase inhibitor, significantly decreased the accumulation of all three in a concentration-dependent manner.

  9. Divalent Metal Ion Transport across Large Biological Ion Channels and Their Effect on Conductance and Selectivity

    Directory of Open Access Journals (Sweden)

    Elena García-Giménez

    2012-01-01

    Full Text Available Electrophysiological characterization of large protein channels, usually displaying multi-ionic transport and weak ion selectivity, is commonly performed at physiological conditions (moderate gradients of KCl solutions at decimolar concentrations buffered at neutral pH. We extend here the characterization of the OmpF porin, a wide channel of the outer membrane of E. coli, by studying the effect of salts of divalent cations on the transport properties of the channel. The regulation of divalent cations concentration is essential in cell metabolism and understanding their effects is of key importance, not only in the channels specifically designed to control their passage but also in other multiionic channels. In particular, in porin channels like OmpF, divalent cations modulate the efficiency of molecules having antimicrobial activity. Taking advantage of the fact that the OmpF channel atomic structure has been resolved both in water and in MgCl2 aqueous solutions, we analyze the single channel conductance and the channel selectivity inversion aiming to separate the role of the electrolyte itself, and the counterion accumulation induced by the protein channel charges and other factors (binding, steric effects, etc. that being of minor importance in salts of monovalent cations become crucial in the case of divalent cations.

  10. Development of an ELISA assay for screening inhibitors against divalent metal ion dependent alphavirus capping enzyme.

    Science.gov (United States)

    Kaur, Ramanjit; Mudgal, Rajat; Narwal, Manju; Tomar, Shailly

    2018-06-26

    Alphavirus non-structural protein, nsP1 has a distinct molecular mechanism of capping the viral RNAs than the conventional capping mechanism of host. Thus, alphavirus capping enzyme nsP1 is a potential drug target. nsP1 catalyzes the methylation of guanosine triphosphate (GTP) by transferring the methyl group from S-adenosylmethionine (SAM) to a GTP molecule at its N7 position with the help of nsP1 methyltransferase (MTase) followed by guanylylation (GT) reaction which involves the formation of m 7 GMP-nsP1 covalent complex by nsP1 guanylyltransferase (GTase). In subsequent reactions, m 7 GMP moiety is added to the 5' end of the viral ppRNA by nsP1 GTase resulting in the formation of cap0 structure. In the present study, chikungunya virus (CHIKV) nsP1 MTase and GT reactions were confirmed by an indirect non-radioactive colorimetric assay and western blot assay using an antibody specific for the m 7 G cap, respectively. The purified recombinant CHIKV nsP1 has been used for the development of a rapid and sensitive non-radioactive enzyme linked immunosorbent assay (ELISA) to identify the inhibitors of CHIKV nsP1. The MTase reaction is followed by GT reaction and resulted in m 7 GMP-nsP1 covalent complex formation. The developed ELISA nsP1 assay measures this m 7 GMP-nsP1 complex by utilizing anti-m 7 G cap monoclonal antibody. The mutation of a conserved residue Asp63 to Ala revealed its role in nsP1 enzyme reaction. Inductively coupled plasma mass spectroscopy (ICP-MS) was used to determine the presence of magnesium ions (Mg 2+ ) in the purified nsP1 protein. The divalent metal ion selectivity and investigation show preference for Mg 2+ ion by CHIKV nsP1. Additionally, using the developed ELISA nsP1 assay, the inhibitory effects of sinefungin, aurintricarboxylic acid (ATA) and ribavirin were determined and the IC 50 values were estimated to be 2.69 µM, 5.72 µM and 1.18 mM, respectively. Copyright © 2018. Published by Elsevier B.V.

  11. Affinity of Smectite and Divalent Metal Ions (Mg(2+), Ca(2+), Cu(2+)) with L-leucine: An Experimental and Theoretical Approach Relevant to Astrobiology.

    Science.gov (United States)

    Pandey, Pramod; Pant, Chandra Kala; Gururani, Kavita; Arora, Priyanka; Pandey, Neetu; Bhatt, Preeti; Sharma, Yogesh; Negi, Jagmohan Singh; Mehata, Mohan Singh

    2015-12-01

    Earth is the only known planet bestowed with life. Several attempts have been made to explore the pathways of the origin of life on planet Earth. The search for the chemistry which gave rise to life has given answers related to the formation of biomonomers, and their adsorption on solid surfaces has gained much attention for the catalysis and stabilization processes related to the abiotic chemical evolution of the complex molecules of life. In this communication, surface interactions of L-leucine (Leu) on smectite (SMT) group of clay (viz. bentonite and montmorillonite) and their divalent metal ion (Mg(2+), Ca(2+) and Cu(2+)) incorporated on SMT has been studied to find the optimal conditions of time, pH, and concentration at ambient temperature (298 K). The progress of adsorption was followed spectrophotometrically and further characterized by FTIR, SEM/EDS and XRD. Leu, a neutral/non polar amino acid, was found to have more affinity in its zwitterionic form towards Cu(2+)- exchanged SMT and minimal affinity for Mg(2+)- exchanged SMT. The vibrational frequency shifts of -NH3 (+) and -COO(-) favor Van der Waal's forces during the course of surface interaction. Quantum calculations using density functional theory (DFT) have been applied to investigate the absolute value of metal ion affinities of Leu (Leu-M(2+) complex, M = Mg(2+), Ca(2+), Cu(2+)) with the help of their physico-chemical parameters. The hydration effect on the relative stability and geometry of the individual species of Leu-M(2+) × (H2O)n, (n =2 and 4) has also been evaluated within the supermolecule approach. Evidence gathered from investigations of surface interactions, divalent metal ions affinities and hydration effects with biomolecules may be important for better understanding of chemical evolution, the stabilization of biomolecules on solid surfaces and biomolecular-metal interactions. These results may have implications for understanding the origin of life and the preservation of

  12. Determining the selectivity of divalent metal cations for the carboxyl group of alginate hydrogel beads during competitive sorption.

    Science.gov (United States)

    An, Byungryul; Lee, Healim; Lee, Soonjae; Lee, Sang-Hyup; Choi, Jae-Woo

    2015-11-15

    To investigate the competitive sorption of divalent metal ions such as Ca(2+), Cu(2+), Ni(2+), and Pb(2+) on alginate hydrogel beads, batch and column tests were conducted. The concentration of carboxyl group was found to be limited in the preparation of spherical hydrogel beads. From kinetic test results, 80% of sorption was observed within 4h, and equilibrium was attained in 48 h. According to the comparison of the total uptake and release, divalent metal ions were found to stoichiometrically interact with the carboxyl group in the alginate polymer chain. From the Langmuir equation, the maximum capacities of Pb(2+), Cu(2+), and Ni(2+) were calculated to be 1.1, 0.48, and 0.13 mmol/g, respectively. The separation factor (α) values for αPb/Cu, αPb/Ni, and αCu/Ni were 14.0, 98.9, and 7.1, respectively. The sorption capacity of Pb(2+) was not affected by the solution pH; however, the sorption capacities of Cu(2+) and Ni(2+) decreased with increasing solution pH, caused by competition with hydrogen. According to the result from the fixed column test, Pb(2+) exhibited the highest affinity, followed by Cu(2+) and Ni(2+), which is in exact agreement with those of kinetic and isotherm tests. The sorbent could be regenerated using 4% HCl, and the regenerated sorbent exhibited 90% capacity upto 9 cycles. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    Energy Technology Data Exchange (ETDEWEB)

    Kayaaltı, Zeliha, E-mail: kayaalti@ankara.edu.tr; Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-02-15

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  14. Evaluation of the effect of divalent metal transporter 1 gene polymorphism on blood iron, lead and cadmium levels

    International Nuclear Information System (INIS)

    Kayaaltı, Zeliha; Akyüzlü, Dilek Kaya; Söylemezoğlu, Tülin

    2015-01-01

    Divalent metal transporter 1 (DMT1), a member of the proton-coupled metal ion transporter family, mediates transport of ferrous iron from the lumen of the intestine into the enterocyte and export of iron from endocytic vesicles. It has an affinity not only for iron but also for other divalent cations including manganese, cobalt, nickel, cadmium, lead, copper, and zinc. DMT1 is encoded by the SLC11a2 gene that is located on chromosome 12q13 in humans and express four major mammalian isoforms (1A/+IRE, 1A/-IRE, 2/+IRE and 2/-IRE). Mutations or polymorphisms of DMT1 gene may have an impact on human health by disturbing metal trafficking. To study the possible association of DMT1 gene with the blood levels of some divalent cations such as iron, lead and cadmium, a single nucleotide polymorphism (SNP) (IVS4+44C/A) in DMT1 gene was investigated in 486 unrelated and healthy individuals in a Turkish population by method of polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP). The genotype frequencies were found as 49.8% homozygote typical (CC), 38.3% heterozygote (CA) and 11.9% homozygote atypical (AA). Metal levels were analyzed by dual atomic absorption spectrometer system and the average levels of iron, lead and cadmium in the blood samples were 446.01±81.87 ppm, 35.59±17.72 ppb and 1.25±0.87 ppb, respectively. Individuals with the CC genotype had higher blood iron, lead and cadmium levels than those with AA and CA genotypes. Highly statistically significant associations were detected between IVS4+44 C/A polymorphism in the DMT1 gene and iron and lead levels (p=0.001 and p=0.036, respectively), but no association was found with cadmium level (p=0.344). This study suggested that DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, lead and cadmium levels. - Highlights: • DMT1 IVS4+44 C/A polymorphism is associated with inter-individual variations in blood iron, cadmium and lead levels.

  15. Polymerization of a divalent/tetravalent metal-storing atom-mimicking dendrimer

    OpenAIRE

    Albrecht, Ken; Hirabayashi, Yuki; Otake, Masaya; Mendori, Shin; Tobari, Yuta; Azuma, Yasuo; Majima, Yutaka; Yamamoto, Kimihisa

    2016-01-01

    The phenylazomethine dendrimer (DPA) has a layer-by-layer electron density gradient that is an analog of the Bohr atom (atom mimicry). In combination with electron pair mimicry, the polymerization of this atom-mimicking dendrimer was achieved. The valency of the mimicked atom was controlled by changing the chemical structure of the dendrimer. By mimicking a divalent atom, a one-dimensional (1D) polymer was obtained, and by using a planar tetravalent atom mimic, a 2D polymer was obtained. Thes...

  16. Biodegradation tests of mercaptocarboxylic acids, their esters, related divalent sulfur compounds and mercaptans.

    Science.gov (United States)

    Rücker, Christoph; Mahmoud, Waleed M M; Schwartz, Dirk; Kümmerer, Klaus

    2018-04-17

    Mercaptocarboxylic acids and their esters, a class of difunctional compounds bearing both a mercapto and a carboxylic acid or ester functional group, are industrial chemicals of potential environmental concern. Biodegradation of such compounds was systematically investigated here, both by literature search and by experiments (Closed Bottle Test OECD 301D and Manometric Respirometry Test OECD 301F). These compounds were found either readily biodegradable or at least biodegradable to a significant extent. Some related compounds of divalent sulfur were tested for comparison (mercaptans, sulfides, disulfides). For the two relevant monofunctional compound classes, carboxylic acids/esters and mercaptans, literature data were compiled, and by comparison with structurally similar compounds without these functional groups, the influence of COOH/COOR' and SH groups on biodegradability was evaluated. Thereby, an existing rule of thumb for biodegradation of carboxylic acids/esters was supported by experimental data, and a rule of thumb could be formulated for mercaptans. Concurrent to biodegradation, abiotic processes were observed in the experiments, rapid oxidative formation of disulfides (dimerisation of monomercaptans and cyclisation of dimercaptans) and hydrolysis of esters. Some problems that compromise the reproducibility of biodegradation test results were discussed.

  17. Radical bonding: structure and stability of bis(phenalenyl) complexes of divalent metals from across the periodic table.

    Science.gov (United States)

    Craciun, Smaranda; Donald, Kelling J

    2009-07-06

    We examine the bonding possibilities of the bis(phenalenyl) MP(2) sandwich complexes of the divalent metals M = Be, Mg, Ca, Sr, Ba, Zn, Cd, and Hg, at the B3LYP level of theory. The outcome is an extraordinarily diverse class of low symmetry bis(phenalenyl)metal complexes in which bonding preferences and binding enthalpies differ dramatically. The lowest energy group 2 metal MP(2) complexes include an intriguing eta(1),eta(3) BeP(2) structure, and bent eta(6),eta(6) systems for M = Ca, Sr, and Ba. The group 12 bis(phenalenyl) complexes are thermodynamically unstable eta(1),eta(1) slip-sandwich structures. To better understand changes in the structural preferences going from the (eta(6),eta(6)) group 2 to the (eta(1),eta(1)) group 12 complexes, we explored the bonding in the bis(phenalenyl) complexes of transition metals with stable +2 oxidations states between Ca and Zn in period 4. The computed binding enthalpies are large and negative for nearly all of the minimum energy bis(phenalenyl) complexes of the group 2 and the transition metals; they are tiny for MgP(2), and are quite positive for the group 12 systems. The structural preferences and stability of the complexes is a subtle negotiation of several influences: the (un)availability of (n - 1)d and np, orbitals for bonding, the cost of the rehybridization at carbon sites in the phenalenyl rings in preparation for bonding to the metals, and the (P---P) interaction between the phenalenyl radicals.

  18. Synthesis, vibrational spectrometry and thermal characterizations of coordination polymers derived from divalent metal ions and hydroxyl terminated polyurethane as ligand

    Science.gov (United States)

    Laxmi; Khan, Shabnam; Kareem, Abdul; Zafar, Fahmina; Nishat, Nahid

    2018-01-01

    A series of novel coordination polyurethanes [HTPU-M, where M = Mn(II) 'd5', Ni(II) 'd8', and Zn(II) 'd10'] have been synthesized to investigate the effect of divalent metal ions coordination on structure, thermal and adsorption properties of low molecular weight hydroxyl terminated polyurethane (HTPU). HTPU-M have been synthesized in situ where, sbnd OH group of HTPU (synthesized by the condensation polymerization reaction of ethylene glycol (EG) and toluene diisocyanate (TDI) in presence of catalyst) on condensation polymerization with metal acetate in presence of acid catalyst synthesized HTPU-M followed by coordination of metal ions with hetero atoms. The structure, composition and geometry of HTPU-M have been confirmed by vibrational spectrometry (FTIR), 1H NMR, elemental analysis and UV-Visible spectroscopy. Morphological structures of HTPU-M were analyzed by X-Ray Diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FE-SEM) with Energy Dispersive X-ray spectroscopy (EDX) and High Resolution Transmission Electron Microscope (HR-TEM) techniques. The thermal degradation pattern and thermal stability of HTPU-M in comparison to HTPU was investigated by thermal-gravimetric (TG)/differential thermal (DT), analyses along with Integral procedure decomposition temperature (IPDT) by Doyle method. The molecular weight of HTPU was determined by gel permeation chromatography (GPC). The preliminary adsorption/desorption studies of HTPU-M for Congo red (CR) was studied by batch adsorption techniques. The results indicated that HTPU-M have amorphous, layered morphology with higher number of nano-sized grooves in comparison to HTPU. Coordination of metal to HTPU plays a key role in enhancing the thermal stability [HTPU-Ni(II) > HTPU-Mn(II) > HTPU-Zn(II) > HTPU]. The HTPU-M can be utilized for industrial waste water treatment by removing environmental pollutants.

  19. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd

    OpenAIRE

    Duguid, J.; Bloomfield, V.A.; Benevides, J.; Thomas Jr, G.J.

    1993-01-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) ind...

  20. Dissolved Divalent Metal and pH Effects on Amino Acid Polymerization: A Thermodynamic Evaluation.

    Science.gov (United States)

    Kitadai, Norio

    2017-03-01

    Polymerization of amino acids is a fundamentally important step for the chemical evolution of life. Nevertheless, its response to changing environmental conditions has not yet been well understood because of the lack of reliable quantitative information. For thermodynamics, detailed prediction over diverse combinations of temperature and pH has been made only for a few amino acid-peptide systems. This study used recently reported thermodynamic dataset for the polymerization of the simplest amino acid "glycine (Gly)" to its short peptides (di-glycine and tri-glycine) to examine chemical and structural characteristics of amino acids and peptides that control the temperature and pH dependence of polymerization. Results showed that the dependency is strongly controlled by the intramolecular distance between the amino and carboxyl groups in an amino acid structure, although the side-chain group role is minor. The polymerization behavior of Gly reported earlier in the literature is therefore expected to be a typical feature for those of α-amino acids. Equilibrium calculations were conducted to examine effects of dissolved metals as a function of pH on the monomer-polymer equilibria of Gly. Results showed that metals shift the equilibria toward the monomer side, particularly at neutral and alkaline pH. Metals that form weak interaction with Gly (e.g., Mg 2+ ) have no noticeable influence on the polymerization, although strong interaction engenders significant decrease of the equilibrium concentrations of Gly peptides. Considering chemical and structural characteristics of Gly and Gly peptides that control their interactions with metals, it can be expected that similar responses to the addition of metals are applicable in the polymerization of neutral α-amino acids. Neutral and alkaline aqueous environments with dissolved metals having high affinity with neutral α-amino acids (e.g., Cu 2+ ) are therefore not beneficial places for peptide bond formation on the primitive

  1. Electronic structure and superconductivity of divalent metals under very high pressure

    International Nuclear Information System (INIS)

    Bireckoven, B.

    1987-05-01

    A single crystal, high-pressure diamond cell has been developed for the study of superconductors under pressures to over 50 GPa. A high sensitivity AC-SQUID magnetometer has been employed to detect the diamagnetic response of the very small samples at T C . The T C (p)-dependence of the lead-manometer has been calibrated against the ruby-pressure-scale up to pressures of 30 GPa. In spite of the well-known fcc/hcp-transition at 13 GPa lead shows a smooth T C (p)-behaviour and thus is a very suitable manometer. Band structure calculations for the alkaline earth metals indicate an appreciable s-to-d transfer with increasing pressure. In fact, superconductivity was previously observed in the pressure induced d-transition metals Sr and Ba (however not yet in Ca). For the first time the author presents a quantitative investigation of T C as a function of p up to 50 GPa. Both elements turn out to be ''good'' superconductors featuring T C 's of about 7 K. The possibility of a generalized phase diagram for the alkaline earth metals will be critically discussed. At any rate, the occurrence of such high T C 's is rather strong evidence for a substantial d-transition metal character at high p. Investigations of very dilute BaEu-alloys up to 45 GPa reveal a strong monotonic increase of ΔT C = T C Ba -T C BaEu . (orig./GSCH)

  2. TOLERANCE OF AGAVE TEQUILANA TO HIGH LEVELS OF DIVALENT METAL CATIONS

    Directory of Open Access Journals (Sweden)

    Elmi Roseida Cen-Cen

    2015-11-01

    Full Text Available Los agaves son plantas que pertenecen a un género constituido por numerosas especies, adaptadas para crecer en muy diversos hábitats, algunos con condiciones ambientales extremas. Distintas especies de agave crecen sobre distintos tipos de suelos, algunas en suelos con muy bajo contenido de nutrientes minerales y otras en suelos salinos o en suelos contaminados con iones metálicos. La relación planta-suelo ha sido escasamente estudiada en este género por lo que se desconoce, entre otras cuestiones, cuál es la capacidad de los agaves para absorber, transportar y almacenar nutrientes minerales, cuáles son los mecanismos celulares y bioquímicos que utilizan, o si poseen especial sensibilidad o tolerancia a los iones metálicos. Este estudio reporta el efecto de diversas concentraciones de sulfato de cadmio, cobalto, cobre, zinc o de manganeso sobre plántulas deAgave tequilana, bajo condiciones controladas de laboratorio; la concentración mínima de esos iones metálicos requerida para inducir un efecto tóxico visualmente detectable en tiempos cortos (ocho días; describimos los efectos tóxicos que estos metales generan sobre las plántulas de agave; y reportamos la cantidad de Cu2+, Cd2+ y Co2+ que se acumula en las hojas de plántulas de agave tratadas con altas concentraciones (milimolares de esos metales. Nuestros resultados muestran que, en experimentos de toxicidad aguda y bajo las condiciones aquí establecidas, elA. tequilanaposee una notable tolerancia a altas concentraciones de los distintos metales iónicos probados, incluyendo tanto micronutrientes como metales tóxicos, así como la capacidad de transportar en altas cantidades estos metales a tejido aéreo.

  3. Potentiometric studies on ternary complexes involving some divalent transition metal ions, gallic acid and biologically abundant aliphatic dicarboxylic acids in aqueous solutions

    Directory of Open Access Journals (Sweden)

    Abdelatty Mohamed Radalla

    2015-06-01

    Full Text Available Formation of binary and ternary complexes of the divalent transition metal ions, Cu2+, Ni2+, Co2+ and Zn2+ with gallic acid and the biologically important aliphatic dicarboxylic acids (adipic, succinic, malic, malonic, maleic, tartaric and oxalic acids were investigated by means of the potentiometric technique at 25 °C and I = 0.10 mol dm−3 NaNO3. The acid-base properties of the ligands were investigated and discussed. The acidity constants of gallic acid and aliphatic dicarboxylic acids were determined and used for determining the stability constants of the binary and ternary complexes formed in the aqueous medium under the above experimental conditions. The formation of the different 1:1 and 1:2 binary complexes and 1:1:1 ternary complexes are inferred from the corresponding potentiometric pH-metric titration curves. The ternary complex formation was found to occur in a stepwise manner. The stability constants of these binary and ternary systems were calculated. The values of Δ log K, percentage of relative stabilization (%R.S. and log X were evaluated and discussed. The concentration distribution of the various complex species formed in solution was evaluated and discussed. The mode of chelation of ternary complexes formed was ascertained by conductivity measurements.

  4. Identification of a divalent metal cation binding site in herpes simplex virus 1 (HSV-1) ICP8 required for HSV replication.

    Science.gov (United States)

    Bryant, Kevin F; Yan, Zhipeng; Dreyfus, David H; Knipe, David M

    2012-06-01

    Herpes simplex virus 1 (HSV-1) ICP8 is a single-stranded DNA-binding protein that is necessary for viral DNA replication and exhibits recombinase activity in vitro. Alignment of the HSV-1 ICP8 amino acid sequence with ICP8 homologs from other herpesviruses revealed conserved aspartic acid (D) and glutamic acid (E) residues. Amino acid residue D1087 was conserved in every ICP8 homolog analyzed, indicating that it is likely critical for ICP8 function. We took a genetic approach to investigate the functions of the conserved ICP8 D and E residues in HSV-1 replication. The E1086A D1087A mutant form of ICP8 failed to support the replication of an ICP8 mutant virus in a complementation assay. E1086A D1087A mutant ICP8 bound DNA, albeit with reduced affinity, demonstrating that the protein is not globally misfolded. This mutant form of ICP8 was also recognized by a conformation-specific antibody, further indicating that its overall structure was intact. A recombinant virus expressing E1086A D1087A mutant ICP8 was defective in viral replication, viral DNA synthesis, and late gene expression in Vero cells. A class of enzymes called DDE recombinases utilize conserved D and E residues to coordinate divalent metal cations in their active sites. We investigated whether the conserved D and E residues in ICP8 were also required for binding metal cations and found that the E1086A D1087A mutant form of ICP8 exhibited altered divalent metal binding in an in vitro iron-induced cleavage assay. These results identify a novel divalent metal cation-binding site in ICP8 that is required for ICP8 functions during viral replication.

  5. Syntheses and crystal structures of a series of new divalent metal phosphonates with imino-bis(methylphosphonic acid)

    International Nuclear Information System (INIS)

    Yang Bingping; Prosvirin, Andrey V.; Zhao, Han-Hua; Mao, Jiang-Gao

    2006-01-01

    Hydrothermal reactions of divalent transition metal salts with imino-bis(methylphosphonic acid), NH(CH 2 PO 3 H 2 ) 2 (H 4 L) afforded three new metal phosphonates, namely, Cu[NH(CH 2 PO 3 H) 2 ] 1, {Co[NH 2 (CH 2 PO 3 H)(CH 2 PO 3 )](H 2 O) 2 }.H 2 O 2 and Mn[NH 2 (CH 2 PO 3 H)(CH 2 PO 3 )](H 2 O) 3. When HO 2 C(CH 2 ) 3 N(CH 2 PO 3 H 2 ) 2 was used as the phosphonate ligand and 4,4'-bipy as the second metal linker, {Cu 4 [NH(CH 2 PO 3 ) 2 ] 2 (4,4'-bipy)(H 2 O) 4 }.9H 2 O 4 with a pillared layered architecture was obtained. The NH(CH 2 PO 3 ) 2 anion resulted from the cleavage of the HO 2 C(CH 2 ) 3 -group during the reaction. Although compounds 1-3 have a same M/L ratio (1:1), they exhibit totally different structures.Compound 1 has a linear chain structure, in which each pair of square-pyramidal coordinated copper(II) ions are bridged by two phosphonate oxygen atoms to form a Cu 2 O 2 dimeric unit, and such dimeric units are further interconnected via phosphonate groups to form a [010] chain. Compound 2 has a layered architecture built from CoO 6 octahedra bridged by phosphonate ligands. In compound 3, the interconnection of the manganese(II) ions by bridging imino-diphosphonate ligands leads to a 3D network. Compound 4 has a pillar-layered structure, the layers composed of Cu(II) ions bridged by aminodiphosphonate ligands are interconnected by 4,4'-bipy ligands to form channels along c-axis. Several factors that affect the structures of the metal phosphonates formed have also been discussed. Compounds 2 and 3 show predominant antiferromagnetic interactions between magnetic centers. -- Graphical abstract: Four new metal phosphonates, namely, Cu[NH(CH 2 PO 3 H) 2 ] 1, {Co[NH 2 (CH 2 PO 3 H)(CH 2 PO 3 )](H 2 O) 2 }.H 2 O 2, Mn[NH 2 (CH 2 PO 3 H)(CH 2 PO 3 )](H 2 O) 3 and {Cu 4 [NH(CH 2 PO 3 ) 2 ] 2 (4,4'-bipy)(H 2 O) 4 }.9H 2 O 4 have been synthesized and structurally characterized. Compound 1 has a linear chain structure, and compound 2 is layered. Compound 3 is

  6. Stability constants for some divalent metal ion/crown ether complexes in methanol determined by polarography and conductometry

    NARCIS (Netherlands)

    Chen, L.; Bos, M.; Grootenhuis, P.D.J.; Christenhusz, A.; Hoogendam, E.; Reinhoudt, David; van der Linden, W.E.

    1987-01-01

    Stability constants in methanol at 25.0°C were evaluated for the complexes of the divalent cations Ca2+, Ni2+, Zn2+, Pb2+, Mg2+, Co2+ and Cu2+ with the macrocyclic polyethers 15-crown-5 (15C5), 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and dibenzo-24-crown-8 (DB24C8). The log K values of

  7. Studies on the effect of divalent metal ions on exfoliative toxins from Staphylococcus hyicus: indications of ExhA and ExhB being metalloproteins.

    Science.gov (United States)

    Andresen, L O

    1999-04-01

    The exfoliative toxins ExhA and ExhB produced by Staphylococcus hyicus strains NCTC10350 and 1289D-88, respectively, were investigated with regard to the effect of divalent metal ions on toxin production as measured in indirect enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies. Data were obtained as endpoint titer values and used as semiquantitative measures for the amount of exfoliative toxin detected in culture supernatants. It was shown that the endpoint titers of ExhA in supernatants from cultures of strain NCTC10350 grown in the presence of 0.5 mM CaCl2, Cu(NO3)2 or ZnSO4 were higher compared to titers obtained by growth in medium supplemented with a number of other divalent metal salts. The titer of ExhB as determined in the indirect ELISA was increased by addition of 0.5 mM CoCl2, Cu(NO3)2 or CuSO4 to the growth medium. When ExhA or ExhB, prepared without addition of metal salt to the liquid growth medium, was subsequently incubated with 25 mM of Co2+, Cu2+ or Zn2+, the endpoint titers of the toxins were increased. Dialysis of ExhA and ExhB prepared with Zn2+ and Co2+, respectively, against certain metal chelators, resulted in a reduction of the titer determined in ELISA. Other metal chelators had varied effect in the detection of the toxins in ELISA. It was, however, not possible to restore the recognition of toxins by the monoclonal antibodies by incubation of EDDHA-dialyzed toxin preparations with Co2+, Cu2+ or Zn2+. The results of this study suggest that ExhA and ExhB are metalloproteins.

  8. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd.

    Science.gov (United States)

    Duguid, J; Bloomfield, V A; Benevides, J; Thomas, G J

    1993-11-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) induce the greatest structural changes in B-DNA. The Raman (vibrational) band differences are extensive and indicate partial disordering of the B-form backbone, reduction in base stacking, reduction in base pairing, and specific metal interaction with acceptor sites on the purine (N7) and pyrimidine (N3) rings. Many of the observed spectral changes parallel those accompanying thermal denaturation of B-DNA and suggest that the metals link the bases of denatured DNA. While exocyclic carbonyls of dT, dG, and dC may stabilize metal ligation, correlation plots show that perturbations of the carbonyls are mainly a consequence of metal-induced denaturation of the double helix. Transition metal interactions with the DNA phosphates are weak in comparison to interactions with the bases, except in the case of Cu2+, which strongly perturbs both base and phosphate group vibrations. On the other hand, the Raman signature of B-DNA is largely unperturbed by Mg2+, Ca2+, Sr2+, and Ba2+, suggesting much weaker interactions of the alkaline earth metals with both base and phosphate sites. A notable exception is a moderate perturbation by alkaline earths of purine N7 sites in 160-base pair DNA, with Ca2+ causing the greatest effect. Correlation plots demonstrate a strong interrelationship between perturbations of Raman bands assigned to ring vibrations of the bases and those of bands assigned to exocyclic carbonyls and backbone phosphodiester groups. However, strong correlations do not occur between

  9. Reversible CO binding enables tunable CO/H₂ and CO/N₂ separations in metal-organic frameworks with exposed divalent metal cations.

    Science.gov (United States)

    Bloch, Eric D; Hudson, Matthew R; Mason, Jarad A; Chavan, Sachin; Crocellà, Valentina; Howe, Joshua D; Lee, Kyuho; Dzubak, Allison L; Queen, Wendy L; Zadrozny, Joseph M; Geier, Stephen J; Lin, Li-Chiang; Gagliardi, Laura; Smit, Berend; Neaton, Jeffrey B; Bordiga, Silvia; Brown, Craig M; Long, Jeffrey R

    2014-07-30

    Six metal-organic frameworks of the M2(dobdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate) structure type are demonstrated to bind carbon monoxide reversibly and at high capacity. Infrared spectra indicate that, upon coordination of CO to the divalent metal cations lining the pores within these frameworks, the C-O stretching frequency is blue-shifted, consistent with nonclassical metal-CO interactions. Structure determinations reveal M-CO distances ranging from 2.09(2) Å for M = Ni to 2.49(1) Å for M = Zn and M-C-O angles ranging from 161.2(7)° for M = Mg to 176.9(6)° for M = Fe. Electronic structure calculations employing density functional theory (DFT) resulted in good agreement with the trends apparent in the infrared spectra and crystal structures. These results represent the first crystallographically characterized magnesium and zinc carbonyl compounds and the first high-spin manganese(II), iron(II), cobalt(II), and nickel(II) carbonyl species. Adsorption isotherms indicate reversible adsorption, with capacities for the Fe, Co, and Ni frameworks approaching one CO per metal cation site at 1 bar, corresponding to loadings as high as 6.0 mmol/g and 157 cm(3)/cm(3). The six frameworks display (negative) isosteric heats of CO adsorption ranging from 52.7 to 27.2 kJ/mol along the series Ni > Co > Fe > Mg > Mn > Zn, following the Irving-Williams stability order. The reversible CO binding suggests that these frameworks may be of utility for the separation of CO from various industrial gas mixtures, including CO/H2 and CO/N2. Selectivities determined from gas adsorption isotherm data using ideal adsorbed solution theory (IAST) over a range of gas compositions at 1 bar and 298 K indicate that all six M2(dobdc) frameworks could potentially be used as solid adsorbents to replace current cryogenic distillation technologies, with the choice of M dictating adsorbent regeneration energy and the level of purity of the resulting gases.

  10. Hemolysis of human red blood cells induced by the combination of diethyldithiocarbamate (DDC) and divalent metals: modulation by anaerobiosis, certain antioxidants and oxidants.

    Science.gov (United States)

    Ginsburg, I; Sadovnic, M; Varani, J; Tirosh, O; Kohen, R

    1999-08-01

    The objective of the present communication is to describe the role played by combinations between diethydithiocarbamate (DDC) and divalent metals in hemolysis of human RBC. RBC which had been treated with DDC (10-50 microM) were moderately hemolyzed (about 50%) upon the addition of subtoxic amounts of Cu2+ (50 microM). However, a much stronger and a faster hemolysis occurred either if mixtures of RBC-DDC were immediately treated either by Co2+ (50 microM) or by a premixture of Cu2+ and Co2+ (Cu:Co) (50 microM). While Fe2+ and Ni2+, at 50 microM, initiated 30-50% hemolysis when combined with DDC (50 microM), on a molar basis, Cd2+ was at least 50 fold more efficient than any of the other metals in the initiation of hemolysis by DDC. On the other hand, neither Mn2+ nor Zn2+, had any hemolysis-initiating effects. Co2+ was the only metal which totally blocked hemolysis if added to DDC prior to the addition of the other metals. Hemolysis by mixtures of DDC + (Cu:Co) was strongly inhibited by anaerobiosis (flushing with nitrogen gas), by the reducing agents glutathione, N-acetyl cysteine, mercaptosuccinate, ascorbate, TEMPO, and alpha-tocopherol, by the PLA2 inhibitorbromophenacylbromide (BrPACBr), by tetracycline as well as by phosphatidyl choline, cholesterol and by trypan blue. However, TEMPO, BrPACBr and PC were the only agents which inhibited hemolysis induced by DDC: Cd2+ complexes. On the other hand, none of the classical scavengers of reactive oxygen species (ROS) employed e.g dimethylthiourea, catalase, histidine, mannitol, sodium benzoate, nor the metal chelators desferal and phenanthroline, had any appreciable inhibitory effects on hemolysis induced by DDC + (Cu:Co). DDC oxidized by H2O2 lost its capacity to act in concert either with Cu2+ or with Cd2+ to hemolyze RBC. While either heating RBC to temperatures greater than 37 degrees C or exposure of the cells to glucose-oxidase-generated peroxide diminished their susceptibility to hemolysis, exposure to the

  11. The role of electrolyte anions (ClO4-, NO3-, and Cl-) in divalent metal (M2+) adsorption on oxide and hydroxide surfaces in salt solutions

    International Nuclear Information System (INIS)

    Criscenti, L.J.; Sverjensky, D.A.

    1999-01-01

    Adsorption of divalent metal ions (M 2+ ) onto oxide and hydroxide surfaces from solutions of strong electrolytes has typically been inferred to take place without the involvement of the electrolyte anion. Only in situations where M 2+ forms a strong enough aqueous complex with the electrolyte anion (for example, CdCl + or PbCl + ) has it been frequently suggested that the metal and the electrolyte anion adsorb simultaneously. A review of experimental data for the adsorption of Cd 2+ , Pb 2+ , Co 2+ , UO 2 2+ , Zn 2+ , Cu 2+ , Ba 2+ , Sr 2+ , and Ca 2+ onto quartz, silica, goethite, hydrous ferric oxide, corundum, γ-alumina, anatase, birnessite, and magnetite, from NaNO 3 , KNO 3 , NaCl, and NaClO 4 solutions over a wide range of ionic strengths (0.0001 M-1.0 M), reveals that transition and heavy metal adsorption behavior with ionic strength is a function of the type of electrolyte. In NaNO 3 solutions, metal adsorption exhibits little or no dependence on the ionic strength of the solution. However, in NaCl solutions, transition and heavy metal adsorption decreases strongly with increasing ionic strength. In NaClO 4 solutions, metal adsorption decreases strongly with increasing ionic strength. In NaClO 4 solutions, metal adsorption exhibits little dependence on ionic strength but is often suggestive of an increase in metal adsorption with increasing ionic strength. Analysis of selected adsorption edges was carried out using the extended triple-layer model and aqueous speciation models that included metal-nitrate, metal-chloride, and metal-hydroxide complexes

  12. Synthesis and characterization of divalent metal complexes with ligand derived from the reaction of 3-aminopyridine and biacetyl

    Directory of Open Access Journals (Sweden)

    RAMESH KUMAR

    2006-09-01

    Full Text Available Divalent cobalt, nickel and copper salts reacted in situ with 3-aminopyridine and biacetyl to form complexes of the type: [M(Ap2biac2X2], where Ap2biac is the ligand and X=Cl, Br, NO3 or NCS. The complexes were analysed and characterized as distorted octahedral by conductance, molecular weight, magnetic, electronic and IR spectral studies. The electronic spectra were interpreted and tentative aassignments made. The infrared spectral studies revealed that two molecules of 3-aminopyridine were joined by molecules of biacetyl through a two carbon atom bridge and that the ligand coordinated through azomethine nitrogen atoms, whereas the pyridine nitrogen does not participate in the coordination. In the far infrared spectra, various metal–ligand vibrations were observed and are discussed.

  13. Effects of inorganic acids and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process.

    Science.gov (United States)

    Zhang, Jian; Xia, Yuguo; Zhang, Li; Chen, Dairong; Jiao, Xiuling

    2015-11-07

    In-depth understanding of the sol-gel process plays an essential role in guiding the preparation of new materials. Herein, the effects of different inorganic acids (HCl, HNO3 and H2SO4) and divalent hydrated metal cations (Mg(2+), Ca(2+), Co(2+), Ni(2+)) on γ-AlOOH sol-gel process were studied based on experiments and density functional theory (DFT) calculations. In these experiments, the sol originating from the γ-AlOOH suspension was formed only with the addition of HCl and HNO3, but not with H2SO4. Furthermore, the DFT calculations showed that the strong adsorption of HSO4(-) on the surface of the γ-AlOOH particles, and the hydrogen in HSO4(-) pointing towards the solvent lead to an unstable configuration of electric double layer (EDL). In the experiment, the gelation time sequence of γ-AlOOH sol obtained by adding metal ions changed when the ionic strength was equal to or greater than 0.198 mol kg(-1). The DFT calculations demonstrated that the adsorption energy of hydrated metal ions on the γ-AlOOH surface can actually make a difference in the sol-gel process.

  14. CE of phytosiderophores and related metal species in plants.

    Science.gov (United States)

    Xuan, Yue; Scheuermann, Enrico B; Meda, Anderson R; Jacob, Peter; von Wirén, Nicolaus; Weber, Günther

    2007-10-01

    Phytosiderophores (PS) and the closely related substance nicotianamine (NA) are key substances in metal uptake into graminaceous plants. Here, the CE separation of these substances and related metal species is demonstrated. In particular, the three PS 2'-deoxymugineic acid (DMA), mugineic acid (MA), and 3-epi-hydroxymugineic acid (epi-HMA), and NA, are separated using MES/Tris buffer at pH 7.3. Moreover, three Fe(III) species of the different PS are separated without any stability problems, which are often present in chromatographic analyses. Also divalent metal species of Cu, Ni, and Zn with the ligands DMA and NA are separated with the same method. By using a special, zwitterionic CE capillary, even the separation of two isomeric Fe(III) chelates with the ligand ethylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid (EDDHA) is possible (i.e., meso-Fe(III)-EDDHA and rac-Fe(III)-EDDHA), and for fast separations of NA and respective divalent and trivalent metal species, a polymer CE microchip with suppressed EOF is described. The proposed CE method is applicable to real plant samples, and enables to detect changes of metal species (Cu-DMA, Ni-NA), which are directly correlated to biological processes.

  15. Sequence of ligand binding and structure change in the diphtheria toxin repressor upon activation by divalent transition metals.

    Science.gov (United States)

    Rangachari, Vijayaraghavan; Marin, Vedrana; Bienkiewicz, Ewa A; Semavina, Maria; Guerrero, Luis; Love, John F; Murphy, John R; Logan, Timothy M

    2005-04-19

    The diphtheria toxin repressor (DtxR) is an Fe(II)-activated transcriptional regulator of iron homeostatic and virulence genes in Corynebacterium diphtheriae. DtxR is a two-domain protein that contains two structurally and functionally distinct metal binding sites. Here, we investigate the molecular steps associated with activation by Ni(II)Cl(2) and Cd(II)Cl(2). Equilibrium binding energetics for Ni(II) were obtained from isothermal titration calorimetry, indicating apparent metal dissociation constants of 0.2 and 1.7 microM for two independent sites. The binding isotherms for Ni(II) and Cd(II) exhibited a characteristic exothermic-endothermic pattern that was used to infer the metal binding sequence by comparing the wild-type isotherm with those of several binding site mutants. These data were complemented by measuring the distance between specific backbone amide nitrogens and the first equivalent of metal through heteronuclear NMR relaxation measurements. Previous studies indicated that metal binding affects a disordered to ordered transition in the metal binding domain. The coupling between metal binding and structure change was investigated using near-UV circular dichroism spectroscopy. Together, the data show that the first equivalent of metal is bound by the primary metal binding site. This binding orients the DNA binding helices and begins to fold the N-terminal domain. Subsequent binding at the ancillary site completes the folding of this domain and formation of the dimer interface. This model is used to explain the behavior of several mutants.

  16. Adsorption performances and mechanisms of the newly synthesized N,N'-di (carboxymethyl) dithiocarbamate chelating resin toward divalent heavy metal ions from aqueous media

    International Nuclear Information System (INIS)

    Jing Xiaosheng; Liu Fuqiang; Yang Xin; Ling Panpan; Li Lanjuan; Long Chao; Li Aimin

    2009-01-01

    N,N'-di (carboxymethyl) dithiocarbamate chelating resin (PSDC) was synthesized by anchoring the chelating agent of N,N'-di (carboxymethyl) dithiocarbamate to the chloromethylated PS-DVB (Cl-PS-DVB) matrix, as a new adsorbent for removing divalent heavy metal ions from waste-stream. The physicochemical structures of Cl-PS-DVB and PSDC were elaborately characterized using Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), and were further morphologically characterized using BET and BJH methods. The adsorption performances of PSDC towards heavy metals such as Cu(II), Pb(II) and Ni(II) were systematically investigated, based upon which the adsorption mechanisms were deeply exploited. For the above target, the classic batch adsorption experiments were conducted to explore the kinetics and isotherms of the removal processes with pH-value, initial concentration, temperature, and contact time as the controlling parameters. The kinetic and isotherm data could be well elucidated with Lagergren-second-order equation and Langmuir model respectively. The strong affinity of PSDC toward these target soft acids could be well demonstrated with the electrostatic attraction and chelating interaction caused by IDA moiety and sulphur which were namely soft bases on the concept of hard and soft acids and bases (HASB). Thermodynamic parameters, involving ΔH o , ΔS o and ΔG o were also calculated from graphical interpretation of the experimental data. The standard heats of adsorption (ΔH o ) were found to be endothermic and the entropy change values (ΔS o ) were calculated to be positive for the adsorption of Cu(II), Pb(II) and Ni(II) ions onto the tested adsorbents. Negative values of ΔG o indicated that adsorption processes for all tested metal ions onto PSDC were spontaneous.

  17. Characterization and application of Mucuna urens seed husk as novel biosorbent for sequestration of some divalent metal ions from solution

    Directory of Open Access Journals (Sweden)

    Linda Obiageli ELUKE

    2017-07-01

    Full Text Available The utilization of Horse-Eye Bean (Mucuna urens Seed Husk (HEBSH as low cost biosorbent for the abstraction of Co (II, Pb (II and Zn (II ions from water was performed. The biosorbent was characterized by the Fourier Transform Infrared (FTIR spectroscopy, X-ray diffraction (XRD and Scanning Electron Microscopy (SEM. The influence of pH, initial metal ion concentration, biosorbent dosage and contact time on the biosorption was studied. Four isotherm and four kinetic models were used to determine the mechanism of biosorption. FTIR showed the presence of some functional groups such as OH, C=O, C=C, C-O, C-Cl on the surface of HEBSH, while XRD and SEM showed amorphous and non-porous surface structure respectively. Optimum biosorption of the metal ions was obtained at pH 6.0, biosorbent dosage 0.1 g, metal concentration 400 mg/L and contact time of 30, 40, and 60 min for Co (II, Zn (II and Pb (II respectively. The Freundlich gave the best fit for the three metal ions (R2 > 0.95 than the Langmuir, Tempkin and Dubinin-Radushkevich models indicating a multilayer biosorption on a heterogenous surface of HEBSH. Kinetic analysis showed the pseudo first order model presented good fits for Zn (II and Pb (II while the pseudo second order model for Co (II. The initial sorption rate h (mg/g min was 2.35 × 10-3, 2.1 × 10-4 and 6.3 × 10-7 for Co (II, Zn (II and Pb (II ions respectively. Liquid film diffusion was found to be the diffusion mechanism of biosorption rather than the intraparticle diffusion. The experimental investigation showed that HEBSH is effective as a low cost alternative biosorbent for the sequestration of heavy metal ions from aqueous stream.

  18. Cross-sectional study of expression of divalent metal transporter-1, transferrin, and hepcidin in blood of smelters who are occupationally exposed to manganese

    Directory of Open Access Journals (Sweden)

    Qiyuan Fan

    2016-09-01

    Full Text Available Background Manganese (Mn is widely used in industries including the manufacture of Mn-iron (Fe alloy. Occupational Mn overexposure causes manganism. Mn is known to affect Fe metabolism; this study was designed to test the hypothesis that workers exposed to Mn may have an altered expression of mRNAs encoding proteins in Fe metabolism. Methods Workers occupationally exposed to Mn (n = 71 from a Mn–Fe alloy factory and control workers without Mn-exposure (n = 48 from a pig-iron plant from Zunyi, China, were recruited for this study. Blood samples were collected into Trizol-containing tubes. Total RNA was isolated, purified, and subjected to real-time RT-PCR analysis. Metal concentrations were quantified by atomic absorption spectrophotometry. Results Working environment and genetic background of both groups were similar except for marked differences in airborne Mn concentrations (0.18 mg/m3 in Mn–Fe alloy factory vs. 0.0022 mg/m3 in pig-Fe plant, and in blood Mn levels (34.3 µg/L vs. 10.4 µg/L. Mn exposure caused a significant decrease in the expression of divalent metal transporter-1 (DMT1, transferrin (Tf and hepcidin by 58.2%, 68.5% and 61.5%, respectively, as compared to controls, while the expression of transferrin receptor (TfR was unaltered. Linear regression analysis revealed that expressions of DMT1, Tf and hepcidin were inversely correlated with the accumulative Mn exposure; the correlation coefficients (r are −0.47, −0.54, and −0.49, respectively (p < 0.01. Conclusion The data suggest that occupational Mn exposure causes decreased expressions of DMT1, Tf and hepcidin in blood cells; the finding will help understand the mechanism underlying Mn exposure-associated alteration in Fe homeostasis among workers.

  19. Divalent metal transporter 1 (DMT1) in the brain: implications for a role in iron transport at the blood-brain barrier, and neuronal and glial pathology.

    Science.gov (United States)

    Skjørringe, Tina; Burkhart, Annette; Johnsen, Kasper Bendix; Moos, Torben

    2015-01-01

    Iron is required in a variety of essential processes in the body. In this review, we focus on iron transport in the brain and the role of the divalent metal transporter 1 (DMT1) vital for iron uptake in most cells. DMT1 locates to cellular membranes and endosomal membranes, where it is a key player in non-transferrin bound iron uptake and transferrin-bound iron uptake, respectively. Four isoforms of DMT1 exist, and their respective characteristics involve a complex cell-specific regulatory machinery all controlling iron transport across these membranes. This complexity reflects the fine balance required in iron homeostasis, as this metal is indispensable in many cell functions but highly toxic when appearing in excess. DMT1 expression in the brain is prominent in neurons. Of serious dispute is the expression of DMT1 in non-neuronal cells. Recent studies imply that DMT1 does exist in endosomes of brain capillary endothelial cells denoting the blood-brain barrier. This supports existing evidence that iron uptake at the BBB occurs by means of transferrin-receptor mediated endocytosis followed by detachment of iron from transferrin inside the acidic compartment of the endosome and DMT1-mediated pumping iron into the cytosol. The subsequent iron transport across the abluminal membrane into the brain likely occurs by ferroportin. The virtual absent expression of transferrin receptors and DMT1 in glial cells, i.e., astrocytes, microglia and oligodendrocytes, suggest that the steady state uptake of iron in glia is much lower than in neurons and/or other mechanisms for iron uptake in these cell types prevail.

  20. Functional analysis of the citrate activator CitO from Enterococcus faecalis implicates a divalent metal in ligand binding

    Directory of Open Access Journals (Sweden)

    Victor S. Blancato

    2016-02-01

    Full Text Available The regulator of citrate metabolism, CitO, from Enterococcus faecalis belongs to the FCD family within the GntR superfamily. In the presence of citrate, CitO binds to cis-acting sequences located upstream of the cit promoters inducing the expression of genes involved in citrate utilization. The quantification of the molecular binding affinities, performed by isothermal titration calorimetry (ITC, indicated that CitO has a high affinity for citrate (KD= 1.2±0.2 µM, while it did not recognize other metabolic intermediates. Based on a structural model of CitO where a putative small molecule and a metal binding site were identified, it was hypothesized that the metal ion is required for citrate binding. In agreement with this model, citrate binding to CitO sharply decreased when the protein was incubated with EDTA. This effect was reverted by the addition of Ni2+, and Zn2+ to a lesser extent. Structure-based site-directed mutagenesis was conducted and it was found that changes to alanine in residues Arg97 and His191 resulted in decreased binding affinities for citrate, as determined by EMSA and ITC. Further assays using lacZ fusions confirmed that these residues in CitO are involved in sensing citrate in vivo. These results indicate that the molecular modifications induced by a ligand and a metal binding in the C-terminal domain of CitO are required for optimal DNA binding activity, and consequently, transcriptional activation.

  1. Mercerized mesoporous date pit activated carbon-A novel adsorbent to sequester potentially toxic divalent heavy metals from water.

    Science.gov (United States)

    Aldawsari, Abdullah; Khan, Moonis Ali; Hameed, B H; Alqadami, Ayoub Abdullah; Siddiqui, Masoom Raza; Alothman, Zeid Abdullah; Ahmed, A Yacine Badjah Hadj

    2017-01-01

    A substantive approach converting waste date pits to mercerized mesoporous date pit activated carbon (DPAC) and utilizing it in the removal of Cd(II), Cu(II), Pb(II), and Zn(II) was reported. In general, rapid heavy metals adsorption kinetics for Co range: 25-100 mg/L was observed, accomplishing 77-97% adsorption within 15 min, finally, attaining equilibrium in 360 min. Linear and non-linear isotherm studies revealed Langmuir model applicability for Cd(II) and Pb(II) adsorption, while Freundlich model was fitted to Zn(II) and Cu(II) adsorption. Maximum monolayer adsorption capacities (qm) for Cd(II), Pb(II), Cu(II), and Zn(II) obtained by non-linear isotherm model at 298 K were 212.1, 133.5, 194.4, and 111 mg/g, respectively. Kinetics modeling parameters showed the applicability of pseudo-second-order model. The activation energy (Ea) magnitude revealed physical nature of adsorption. Maximum elution of Cu(II) (81.6%), Zn(II) (70.1%), Pb(II) (96%), and Cd(II) (78.2%) were observed with 0.1 M HCl. Thermogravimetric analysis of DPAC showed a total weight loss (in two-stages) of 28.3%. Infra-red spectral analysis showed the presence of carboxyl and hydroxyl groups over DPAC surface. The peaks at 820, 825, 845 and 885 cm-1 attributed to Zn-O, Pb-O, Cd-O, and Cu-O appeared on heavy metals saturated DPAC, confirmed their binding on DPAC during the adsorption.

  2. Synthesis, characterization and anti-bacterial activity of divalent transition metal complexes of hydrazine and trimesic acid

    Directory of Open Access Journals (Sweden)

    K. Kumar

    2018-01-01

    Full Text Available Transition metal complexes of trimesic acid and hydrazine mixed-ligands with a general formula M(Htma(N2H42, where, M = Mn, Co, Ni, Cu and Zn; H3tma = trimesic acid, have been prepared and characterized by elemental, structural, spectral and thermal analyses. For the complexes, the carboxylate νasym and νsym stretchings are observed at about 1626 and 1367 cm−1 respectively, with Δν between them of ∼260 cm−1, showing the unidentate coordination of each carboxylate group. The hydrazine moieties are present as bridging bidentates. Electronic and EPR spectral studies suggest an octahedral geometry for the complexes. All these complexes show three steps of decomposition in TGA/DTA. SEM images of CuO and MnO residues obtained from the complexes show nano-sized clusters suggesting that the complexes may be used as precursors for nano-CuO and nano-MnO preparation. The antimicrobial activities of the prepared complexes, against four bacteria have been evaluated.

  3. Trace Metals in Groundwater and the Vadose Zone Calcite: In Situ Containment and Stabilization of Strontium-90 and Other Divalent Metals and Radionuclides at Arid West DOE

    International Nuclear Information System (INIS)

    Smith, Robert W.

    2004-01-01

    Radionuclide and metal contaminants such as strontium-90 are present beneath U.S. Department of Energy (DOE) lands in both the groundwater (e.g., 100-N area at Hanford, WA) and vadose zone (e.g., Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory). In situ containment and stabilization of these contaminants is a cost-effective treatment strategy. However, implementing in situ containment and stabilization approaches requires definition of the mechanisms that control contaminant sequestration. We are investigating the in situ immobilization of radionuclides or contaminant metals (e.g., strontium-90) by their facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Our facilitated approach, shown schematically in Figure 1, relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity. Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface urea hydrolyzing microorganisms. Because the precipitation process tends to be irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from the aqueous phase over the long-term. Another advantage of the ureolysis approach is that the ammonium ions produced by the reaction can exchange with radionuclides sorbed to subsurface minerals, thereby enhancing the availability of the radionuclides for re-capture in a more stable solid phase (co-precipitation rather than adsorption)

  4. Redox-active on-surface polymerization of single-site divalent cations from pure metals by a ketone-functionalized phenanthroline

    Energy Technology Data Exchange (ETDEWEB)

    Skomski, Daniel; Tempas, Christopher D.; Bukowski, Gregory S.; Smith, Kevin A.; Tait, Steven L., E-mail: tait@indiana.edu [Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, Indiana 47405 (United States)

    2015-03-14

    Metallic iron, chromium, or platinum mixing with a ketone-functionalized phenanthroline ligand on a single crystal gold surface demonstrates redox activity to a well-defined oxidation state and assembly into thermally stable, one dimensional, polymeric chains. The diverging ligand geometry incorporates redox-active sub-units and bi-dentate binding sites. The gold surface provides a stable adsorption environment and directs growth of the polymeric chains, but is inert with regard to the redox chemistry. These systems are characterized by scanning tunnelling microscopy, non-contact atomic force microscopy, and X-ray photoelectron spectroscopy under ultra-high vacuum conditions. The relative propensity of the metals to interact with the ketone group is examined, and it is found that Fe and Cr more readily complex the ligand than Pt. The formation and stabilization of well-defined transition metal single-sites at surfaces may open new routes to achieve higher selectivity in heterogeneous catalysts.

  5. Structural analysis of inter-genus complexes of V-antigen and its regulator and their stabilization by divalent metal ions.

    Science.gov (United States)

    Basu, Abhishek; Das, Atanu; Mondal, Abhisek; Datta, Saumen

    2016-03-01

    Gram-negative bacteria like Yersinia, Pseudomonas, and Aeromonas need type III secretion system (T3SS) for their pathogenicity. V-antigen and its regulator are essential for functioning of T3SS. There is significant functional conservation amongst V-antigen and its regulator belonging to the Ysc family. In this study, we have structurally characterized the inter-genus complexes of V-antigen and its regulator. ConSurf analysis demonstrates that V-antigens belonging to the Ysc family show high structural identity predominantly confined to the two long helical regions. The regulator of V-antigen shows high conservation in its first intramolecular coiled-coil domain, responsible for interaction with V-antigen. ∆LcrG(1-70) localizes within the groove formed by long helices of LcrV, as observed in PcrV-∆PcrG(13-72) interaction. Inter-genus complexes of LcrV-PcrG and PcrV-LcrG exhibited elongated conformation and 1:1 heterodimeric state like the native complex of PcrV-PcrG and LcrV-LcrG. Both native and inter-genus complexes showed rigid tertiary structure, solvent-exposed hydrophobic patches, and cooperative melting behavior with high melting temperature. LcrV-PcrG and PcrV-LcrG showed nanomolar affinity of interaction, identical to PcrV-PcrG interaction, but stronger than LcrV-LcrG interaction. Calcium (a secretion blocker of T3SS) propels all the complexes towards a highly monodisperse form. Calcium and magnesium increase the helicity of the native and inter-genus complexes, and causes helix-helix stabilization. Stabilization of helices leads to a slight increase in the melting temperature by 1.5-2.0 °C. However, calcium does not alter the affinity of interaction of V-antigen and its regulator, emphasizing the effect of divalent of cations at the structural level without any regulatory implications. Therefore, the structural conservation of these inter-genus complexes could be the basis for their functional complementation.

  6. Studies on the effect of divalent metal ions on exfoliative toxins from Staphylococcus hyicus: indications of ExhA and ExhB being metalloproteins

    DEFF Research Database (Denmark)

    Andresen, Lars Ole

    1999-01-01

    determined in ELISA. Other metal chelators had varied effect in the detection of the toxins in ELISA. It was, however, not possible to restore the recognition of toxins by the monoclonal antibodies by incubation of EDDHA-dialyzed toxin preparations with Co2+, Cu2+ or Zn2+. The results of this study suggest...

  7. Synthesis, crystal structure, and magnetic properties of two-dimensional divalent metal glutarate/dipyridylamine coordination polymers, with a single crystal-to-single crystal transformation in the copper derivative

    International Nuclear Information System (INIS)

    Montney, Matthew R.; Supkowski, Ronald M.; Staples, Richard J.; LaDuca, Robert L.

    2009-01-01

    Hydrothermal reaction of divalent metal chlorides with glutaric acid and 4,4'-dipyridylamine (dpa) has afforded an isostructural family of coordination polymers with formulation [M(glu)(dpa)] n (M=Co (1), Ni (2), Cu (3); glu=glutarate). Square pyramidal coordination is seen in 1-3, with semi-ligation of a sixth donor to produce a '5+1' extended coordination sphere. Neighboring metal atoms are linked into 1D [M(glu)] n neutral chains through chelating/monodentate bridging glutarate moieties with a syn-anti binding mode, and semi-chelation of the pendant carboxylate oxygen. These chains further connect into 2D layers through dipodal dpa ligands. Neighboring layers stack into the pseudo 3D crystal structure of 1-3 through supramolecular hydrogen bonding between dpa amine units and the semi-chelated glutarate oxygen atoms. The variable temperature magnetic behavior of 1-3 was explored and modeled as infinite 1D Heisenberg chains. Notably, complex 3 undergoes a thermally induced single crystal-to-single crystal transformation between centric and acentric space groups, with a conformationally disordered unilayer structure at 293 K and an ordered bilayer structure at 173 K. All materials were further characterized via infrared spectroscopy and elemental and thermogravimetric analyses. - Graphical abstract: The coordination polymers [M(glu)(dpa)] n (M=Co (1), Ni (2), Cu (3); glu=glutarate, dpa=4,4'-dipyridylamine) exhibit 2D layer structures based on 1D [M(glu)] n chains linked through dpa tethers. Antiferromagnetic coupling is observed for 2 and 3, while ferromagnetism is predominant in 1. Compound 3 undergoes a thermally induced single crystal-to-single crystal transformation from an acentric to a centrosymmetric space group

  8. Extraction of Some Divalent Metal Ions (Cadmium, Nickel and Lead from Different Tea and Rice Samples Using Ghezeljeh Nanoclay (Geleh-Sar-Shoor as a New Natural Sorbent

    Directory of Open Access Journals (Sweden)

    Zahra Hassanzadeh Siahpoosh

    2016-12-01

    Full Text Available This article presents the method of extraction-preconcentration of Lead, Cadmium, and Nickel ions from food samples using the Ghezeljeh montmorillonite nanoclay (Geleh-Sar-Shoor as a new native adsorbent in batch single component systems. The extraction-preconcentration of heavy metals were carried out by applying the solid phase extraction (SPE method followed by atomic absorption spectroscopy (AAS, and inductively coupled with plasma atomic emission spectroscopy (ICP-AES. The Ghezeljeh nanoclay was characterized by using Fourier transform infrared spectroscopy (FT-IR, Scanning electron microscopy-energy dispersive spectrometer operating (SEM-EDS, X-ray diffractometry (XRD, X-ray fluorescence (XRF, Cation Exchange Capacity (CEC measurements, BET specific surface area and Zeta potential. According to BET theory, the specific surface areas of the Ghezeljeh nanoclay was calculated to be 19.8 m2 g-1 whereas the cation exchange capacity was measured to be 150 meq/100 g. The results of XRD, XRF, FT-IR, Zeta potential and BET surface area of the nanoclay confirmed that montmorillonite was the dominant mineral phase. Based on SEM images of this clay, it can be seen that the distance between the plates is nm level. For all three ions, the detection and quantification limits, dynamic linear range, preconcentration factor, and adsorption capacity were obtained. The effect of various interfering ions was studied. The experimental method was successfully applied for the extraction of heavy metals in different tea and rice samples.

  9. Synthesis, structural characterization, electrochemical and biological studies on divalent metal chelates of a new ligand derived from pharmaceutical preservative, dehydroacetic acid, with 1,4-diaminobenzene

    Directory of Open Access Journals (Sweden)

    Sanaa M. Emam

    2017-05-01

    Full Text Available Cobalt(II, nickel(II, copper(II, zinc(II and cadmium(II complexes of new 3-acetyl-4-[(4-aminophenylamino]-6-methyl-2H-pyran-2-one (HL1 derived from dehydroacetic acid and 1,4-diaminobenzene were prepared and characterized. The structural features were determined from their elemental analyses, 1H, and 13C-NMR spectra, molar conductivities, magnetic moments, IR, UVvis. spectra, thermal analyses (D.T.A. and T.G.A. and E.S.R. measurements. Their magnetic susceptibility measurements and low conductance data provide evidence for the mono- or dimeric and non-electrolytic nature of the solid complexes. The E.S.R. spectra of copper(II complexes show axial type symmetry with covalent or ionic bond character. The electrochemical behavior of the complexes in DMF (dimethylformamide solvent at 298 K was studied. The biological activity of the ligand and its metal(II complexes was also studied. The obtained complexes showed higher activities than the free ligand in protecting the Egyptian cotton fields from Spodoptera littoralis larvae.

  10. Adsorption and preconcentration of divalent metal ions in fossil fuels and biofuels: gasoline, diesel, biodiesel, diesel-like and ethanol by using chitosan microspheres and thermodynamic approach.

    Science.gov (United States)

    Prado, Alexandre G S; Pescara, Igor C; Evangelista, Sheila M; Holanda, Matheus S; Andrade, Romulo D; Suarez, Paulo A Z; Zara, Luiz F

    2011-05-15

    Biodiesel and diesel-like have been obtained from soybean oil by transesterification and thermal cracking process, respectively. These biofuels were characterized as according to ANP standards by using specific ASTM methods. Ethanol, gasoline, and diesel were purchased from a gas station. Deacetylation degree of chitosan was determined by three distinct methods (conductimetry, FTIR and NMR), and the average degree was 78.95%. The chitosan microspheres were prepared from chitosan by split-coating and these spheres were crosslinked using glutaraldehyde. The surface area of microspheres was determined by BET method, and the surface area of crosslinked microspheres was 9.2m(2)g(-1). The adsorption isotherms of cooper, nickel and zinc on microspheres of chitosan were determined in petroleum derivatives (gasoline and diesel oil), as well as in biofuels (alcohol, biodiesel and diesel-like). The adsorption order in all fuels was: Cu>Ni>Zn. The elution tests presented the following preconcentration degrees: >4.5 to ethanol, >4.4 to gasoline, >4.0 to diesel, >3.8 to biodiesel and >3.6 to diesel-like. The application of chitosan microspheres in the metal ions preconcentration showed the potential of this biopolymer to enrich fuel sample in order to be analyzed by flame atomic absorption spectrometry. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Oil Spill Related Heavy Metal: A Review

    International Nuclear Information System (INIS)

    Ahmad Dasuki Mustafa; Hafizan Juahir; Kamaruzzaman Yunus; Mohammad Azizi Amran; Che Noraini Che Hasnam; Fazureen Azaman; Ismail Zainal Abidin; Syahril Hirman Azmee; Nur Hishaam Sulaiman

    2015-01-01

    Oil spill occurs every day worldwide and oil contamination is a significant contributor for the higher levels of heavy metals in the environment. This study is purposely to summarize the heavy metals which significant to major oil spill incidents around the world and effects of toxic metals to human health. The study performed a comprehensive review of relevant scientific journal articles and government documents concerning heavy metals contamination and oil spills. Overall, the heavy metals most frequently been detected in oil spill related study where Pb>Ni>V>Zn>Cd and caused many effects to human health especially cancer. In conclusion, the comparison of heavy metal level between the post - spill and baseline levels must be done, and implementation of continuous monitoring of heavy metal. In addition, the result based on the strategies must be transparent to public in order to maintaining human health. (author)

  12. Reaction of N,N’-dimethylformamide and divalent viologen molecule to generate an organic dopant for molybdenum disulfide

    Directory of Open Access Journals (Sweden)

    A. Fukui

    2018-05-01

    Full Text Available Tuning the carrier concentration is essential for semiconducting materials to apply optoelectronic devices. Molybdenum disulfide (MoS2 is a semiconducting material composed of atomically thin (∼0.7 nm thickness layers. To dope thin MoS2, instead of using conventional atom/ion injection processes, a surface charge transfer method was successfully applied. In this study, we report a simple preparation method of a molecular dopant applicable to the doping process. The method follows a previous report for producing a molecular dopant, benzyl viologen (BV which shows electron doping to MoS2. To prepare dopant BV molecules, a reduction process with a commercially available divalent BV by sodium borohydride (NaBH4 is required; however, the reaction requires a large consumption of NaBH4. NaBH4 drastically reacts with the solvent water itself. We found a reaction process of BV in an organic solvent, N,N’-dimethylformamide (DMF, by adding a small amount of water dissolving the divalent BV. The reaction is mild (at room temperature and is autonomous once DMF comes into contact with the divalent BV aqueous solution. The reaction can be monitored with a UV-Vis spectrometer, and kinetic analysis indicates two reaction steps between divalent/monovalent/neutral viologen isomers. The product was soluble in toluene and did not dissolve in water, indicating it is similar to the reported dopant BV. The synthesized molecule was found to act as a dopant for MoS2 by applying a metal-oxide-semiconductor field-effect-transistor (MOSFET structure. The process is a general method and applicable to other viologen-related dopants to tune the electronic structure of 2D materials to facilitate generating atomically thin devices.

  13. Comparative sensitivity of rat cerebellar neurons to dysregulation of divalent cation homeostasis and cytotoxicity caused by methylmercury

    International Nuclear Information System (INIS)

    Edwards, Joshua R.; Marty, M. Sue; Atchison, William D.

    2005-01-01

    The objective of the present study was to determine the relative effectiveness of methylmercury (MeHg) to alter divalent cation homeostasis and cause cell death in MeHg-resistant cerebellar Purkinje and MeHg-sensitive granule neurons. Application of 0.5-5 μM MeHg to Purkinje and granule cells grown in culture caused a concentration- and time-dependent biphasic increase in fura-2 fluorescence. At 0.5 and 1 μM MeHg, the elevations of fura-2 fluorescence induced by MeHg were biphasic in both cell types, but significantly delayed in Purkinje as compared to granule cells. Application of the heavy-metal chelator, TPEN, to Purkinje cells caused a precipitous decline in a proportion of the fura-2 fluorescence signal, indicating that MeHg causes release of Ca 2+ and non-Ca 2+ divalent cations. Purkinje cells were also more resistant than granule cells to the neurotoxic effects of MeHg. At 24.5 h after-application of 5 μM MeHg, 97.7% of Purkinje cells were viable. At 3 μM MeHg there was no detectable loss of Purkinje cell viability. In contrast, only 40.6% of cerebellar granule cells were alive 24.5 h after application of 3 μM MeHg. In conclusion, Purkinje neurons in primary cultures appear to be more resistant to MeHg-induced dysregulation of divalent cation homeostasis and subsequent cell death when compared to cerebellar granule cells. There is a significant component of non-Ca 2+ divalent cation released by MeHg in Purkinje neurons

  14. Reaction of N,N'-dimethylformamide and divalent viologen molecule to generate an organic dopant for molybdenum disulfide

    Science.gov (United States)

    Fukui, A.; Miura, K.; Ichimiya, H.; Tsurusaki, A.; Kariya, K.; Yoshimura, T.; Ashida, A.; Fujimura, N.; Kiriya, D.

    2018-05-01

    Tuning the carrier concentration is essential for semiconducting materials to apply optoelectronic devices. Molybdenum disulfide (MoS2) is a semiconducting material composed of atomically thin (˜0.7 nm thickness) layers. To dope thin MoS2, instead of using conventional atom/ion injection processes, a surface charge transfer method was successfully applied. In this study, we report a simple preparation method of a molecular dopant applicable to the doping process. The method follows a previous report for producing a molecular dopant, benzyl viologen (BV) which shows electron doping to MoS2. To prepare dopant BV molecules, a reduction process with a commercially available divalent BV by sodium borohydride (NaBH4) is required; however, the reaction requires a large consumption of NaBH4. NaBH4 drastically reacts with the solvent water itself. We found a reaction process of BV in an organic solvent, N,N'-dimethylformamide (DMF), by adding a small amount of water dissolving the divalent BV. The reaction is mild (at room temperature) and is autonomous once DMF comes into contact with the divalent BV aqueous solution. The reaction can be monitored with a UV-Vis spectrometer, and kinetic analysis indicates two reaction steps between divalent/monovalent/neutral viologen isomers. The product was soluble in toluene and did not dissolve in water, indicating it is similar to the reported dopant BV. The synthesized molecule was found to act as a dopant for MoS2 by applying a metal-oxide-semiconductor field-effect-transistor (MOSFET) structure. The process is a general method and applicable to other viologen-related dopants to tune the electronic structure of 2D materials to facilitate generating atomically thin devices.

  15. Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Stronthium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.; Fujita, Yoshiko

    2007-11-07

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers’ exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadose zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the

  16. Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Strontium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

    International Nuclear Information System (INIS)

    Smith, Robert W.; Fujita, Yoshiko

    2007-01-01

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadose zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the

  17. Heavy metals and related trace elements

    International Nuclear Information System (INIS)

    Leland, H.V.; Luoma, S.N.; Wilkes, D.J.

    1977-01-01

    A review is given of heavy metals and related trace elements in the aquatic environment. Other reviews and bibliographies are cited, dealing with the metabolism and transport of metal ions and with the toxic effects of stable and radioactive trace metals on aquatic organisms. The sources of trace elements in natural waters are discussed. It is suggested that atmospheric inputs of several trace metals comprise sizable fractions of total inputs to the Great Lakes and continental shelf waters. Information on stack emissions of trace elements from a coal-fired steam plant was used to estimate the likely range of air concentrations and inputs to a forested watershed in Tennessee. Some basic concepts of cycling of elements through aquatic communities were examined, such as the Pb, Mn and Zn concentrations in sediment and estuarine plants and animals colonizing dredge-spoil disposal areas. The use of plants as biological indicators of trace element contamination was outlined, as well as bioaccumulation in aquatic fauna. The effects of environmental factors on the kinetics of element exchange were noted, for example the influx rates of Cs 137 in tubificid worms, and Co 60 and Zn 65 in shrimp were shown to be temperature dependent. The toxicity of heavy metals on aquatic fauna was discussed, such as the histopathological lesions in the kidney and liver of fishes caused by heavy metals, and the effects of Hg and Cu on the olfactory response of rainbow trout

  18. CHARACTERIZATION OF METAL BENZOTRIAZOLES AND RELATED POLYMERS

    Science.gov (United States)

    Benzotriazole (bta-H) is a well-known corrosion inhibitor for copper, copper-alloy, and other metal surfaces. Typical uses are to deactivate surfaces of computer hard drives and other internal metal computer parts, and for treatment of apparel hardware such as zippers and buttons...

  19. Interactions of hydrated divalent metal cations with nucleic acid bases. How to relate the gas phase data to solution situation and binding selectivity in nucleic acids

    Czech Academy of Sciences Publication Activity Database

    Šponer, Judit E.; Sychrovský, Vladimír; Hobza, Pavel; Šponer, Jiří

    2004-01-01

    Roč. 6, č. 10 (2004), s. 2772-2780 ISSN 1463-9076 R&D Projects: GA MŠk LN00A016; GA MŠk LN00A032 Grant - others:Wellcome Trust(GB) GR067507MF Institutional research plan: CEZ:AV0Z5004920 Keywords : nucleic acids * gas phase * guanine Subject RIV: BO - Biophysics Impact factor: 2.076, year: 2004

  20. Divalent cations in tears, and their influence on tear film stability in humans and rabbits.

    Science.gov (United States)

    Wei, Xiaojia Eric; Markoulli, Maria; Millar, Thomas J; Willcox, Mark D P; Zhao, Zhenjun

    2012-06-05

    Reduced tear film stability is reported to contribute to dry eye. Rabbits are known to have a more stable tear film than humans. Thus, we sought to examine the tears of rabbits and humans for metal cations, and to test how they influence tear film stability. Tears were collected from 10 healthy humans and 6 rabbits. Tear osmolality was measured by vapor pressure osmometer, and metals analyzed using inductively coupled plasma (ICP) mass spectrometry or ICP atomic emission spectroscopy. The influence of divalent cations on tears was analyzed by measuring surface tension using the Langmuir trough in vitro, using different concentrations of cations in the subphase, and grading the tear break-up in rabbits in vivo after instillation of chelating agents. Rabbit tears had a higher osmolality compared to humans. Major metals did not differ between species; however, rabbits had higher levels of Mg(2+) (1.13 vs. 0.39 mM) and Ca(2+) (0.75 vs. 0.36 mM). In rabbit tears in vitro, diminishing divalent cations resulted in a decrease in the maximum surface pressure from 37 to 30 mN/m. In vivo, an increase in the amount of tear film that was broken-up was found. In contrast, when changing divalent cation concentrations in human tears, the maximum surface pressure remained at 26 mN/m. The normal osmolality of rabbit tears is significantly higher than that in humans. While divalent cations had little influence on human tears, they appear to have an important role in maintaining tear film stability in rabbits.

  1. Synthesis and Characterization of Divalent Manganese, Iron, and Cobalt Complexes in Tripodal Phenolate/N-Heterocyclic Carbene Ligand Environments

    DEFF Research Database (Denmark)

    Käß, Martina; Hohenberger, Johannes; Adelhardt, Mario

    2014-01-01

    . The complete ligand series offers a convenient way of tuning the electronic and steric environment around the metal center, thus, allowing for control of the complex’s reactivity. This series of divalent complexes of Mn, Fe, and Co was synthesized and characterized by 1H NMR, IR, and UV/vis spectroscopy...... as well as by single-crystal X-ray diffraction studies. Variable-temperature SQUID magnetization measurements in the range from 2 to 300 K confirmed high-spin ground states for all divalent complexes and revealed a trend of increasing zero-field splitting |D| from Mn(II), to Fe(II), to Co(II) complexes...

  2. Lysosome-related organelles as mediators of metal homeostasis.

    Science.gov (United States)

    Blaby-Haas, Crysten E; Merchant, Sabeeha S

    2014-10-10

    Metal ion assimilation is essential for all forms of life. However, organisms must properly control the availability of these nutrients within the cell to avoid inactivating proteins by mismetallation. To safeguard against an imbalance between supply and demand in eukaryotes, intracellular compartments contain metal transporters that load and unload metals. Although the vacuoles of Saccharomyces cerevisiae and Arabidopsis thaliana are well established locales for the storage of copper, zinc, iron, and manganese, related compartments are emerging as important mediators of metal homeostasis. Here we describe these compartments and review their metal transporter complement. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. The universal relation of galactic chemical evolution: the origin of the mass-metallicity relation

    International Nuclear Information System (INIS)

    Zahid, H. Jabran; Dima, Gabriel I.; Kudritzki, Rolf-Peter; Kewley, Lisa J.; Geller, Margaret J.; Hwang, Ho Seong; Silverman, John D.; Kashino, Daichi

    2014-01-01

    We examine the mass-metallicity relation for z ≲ 1.6. The mass-metallicity relation follows a steep slope with a turnover, or 'knee', at stellar masses around 10 10 M ☉ . At stellar masses higher than the characteristic turnover mass, the mass-metallicity relation flattens as metallicities begin to saturate. We show that the redshift evolution of the mass-metallicity relation depends only on the evolution of the characteristic turnover mass. The relationship between metallicity and the stellar mass normalized to the characteristic turnover mass is independent of redshift. We find that the redshift-independent slope of the mass-metallicity relation is set by the slope of the relationship between gas mass and stellar mass. The turnover in the mass-metallicity relation occurs when the gas-phase oxygen abundance is high enough that the amount of oxygen locked up in low-mass stars is an appreciable fraction of the amount of oxygen produced by massive stars. The characteristic turnover mass is the stellar mass, where the stellar-to-gas mass ratio is unity. Numerical modeling suggests that the relationship between metallicity and the stellar-to-gas mass ratio is a redshift-independent, universal relationship followed by all galaxies as they evolve. The mass-metallicity relation originates from this more fundamental universal relationship between metallicity and the stellar-to-gas mass ratio. We test the validity of this universal metallicity relation in local galaxies where stellar mass, metallicity, and gas mass measurements are available. The data are consistent with a universal metallicity relation. We derive an equation for estimating the hydrogen gas mass from measurements of stellar mass and metallicity valid for z ≲ 1.6 and predict the cosmological evolution of galactic gas masses.

  4. Highly reversible open framework nanoscale electrodes for divalent ion batteries.

    Science.gov (United States)

    Wang, Richard Y; Wessells, Colin D; Huggins, Robert A; Cui, Yi

    2013-01-01

    The reversible insertion of monovalent ions such as lithium into electrode materials has enabled the development of rechargeable batteries with high energy density. Reversible insertion of divalent ions such as magnesium would allow the creation of new battery chemistries that are potentially safer and cheaper than lithium-based batteries. Here we report that nanomaterials in the Prussian Blue family of open framework materials, such as nickel hexacyanoferrate, allow for the reversible insertion of aqueous alkaline earth divalent ions, including Mg(2+), Ca(2+), Sr(2+), and Ba(2+). We show unprecedented long cycle life and high rate performance for divalent ion insertion. Our results represent a step forward and pave the way for future development in divalent batteries.

  5. THE METALLICITIES OF LOW STELLAR MASS GALAXIES AND THE SCATTER IN THE MASS-METALLICITY RELATION

    International Nuclear Information System (INIS)

    Zahid, H. J.; Bresolin, F.; Kewley, L. J.; Coil, A. L.; Davé, R.

    2012-01-01

    In this investigation, we quantify the metallicities of low-mass galaxies by constructing the most comprehensive census to date. We use galaxies from the Sloan Digital Sky Survey (SDSS) and DEEP2 survey and estimate metallicities from their optical emission lines. We also use two smaller samples from the literature that have metallicities determined by the direct method using the temperature sensitive [O III]λ4363 line. We examine the scatter in the local mass-metallicity (MZ) relation determined from ∼20,000 star-forming galaxies in the SDSS and show that it is larger at lower stellar masses, consistent with the theoretical scatter in the MZ relation determined from hydrodynamical simulations. We determine a lower limit for the scatter in metallicities of galaxies down to stellar masses of ∼10 7 M ☉ which is only slightly smaller than the expected scatter inferred from the SDSS MZ relation and significantly larger than what has been previously established in the literature. The average metallicity of star-forming galaxies increases with stellar mass. By examining the scatter in the SDSS MZ relation, we show that this is mostly due to the lowest metallicity galaxies. The population of low-mass, metal-rich galaxies have properties that are consistent with previously identified galaxies that may be transitional objects between gas-rich dwarf irregulars and gas-poor dwarf spheroidals and ellipticals.

  6. Drosophila melanogaster Models of Metal-Related Human Diseases and Metal Toxicity.

    Science.gov (United States)

    Calap-Quintana, Pablo; González-Fernández, Javier; Sebastiá-Ortega, Noelia; Llorens, José Vicente; Moltó, María Dolores

    2017-07-06

    Iron, copper and zinc are transition metals essential for life because they are required in a multitude of biological processes. Organisms have evolved to acquire metals from nutrition and to maintain adequate levels of each metal to avoid damaging effects associated with its deficiency, excess or misplacement. Interestingly, the main components of metal homeostatic pathways are conserved, with many orthologues of the human metal-related genes having been identified and characterized in Drosophila melanogaster . Drosophila has gained appreciation as a useful model for studying human diseases, including those caused by mutations in pathways controlling cellular metal homeostasis. Flies have many advantages in the laboratory, such as a short life cycle, easy handling and inexpensive maintenance. Furthermore, they can be raised in a large number. In addition, flies are greatly appreciated because they offer a considerable number of genetic tools to address some of the unresolved questions concerning disease pathology, which in turn could contribute to our understanding of the metal metabolism and homeostasis. This review recapitulates the metabolism of the principal transition metals, namely iron, zinc and copper, in Drosophila and the utility of this organism as an experimental model to explore the role of metal dyshomeostasis in different human diseases. Finally, a summary of the contribution of Drosophila as a model for testing metal toxicity is provided.

  7. Similar star formation rate and metallicity variability time-scales drive the fundamental metallicity relation

    Science.gov (United States)

    Torrey, Paul; Vogelsberger, Mark; Hernquist, Lars; McKinnon, Ryan; Marinacci, Federico; Simcoe, Robert A.; Springel, Volker; Pillepich, Annalisa; Naiman, Jill; Pakmor, Rüdiger; Weinberger, Rainer; Nelson, Dylan; Genel, Shy

    2018-06-01

    The fundamental metallicity relation (FMR) is a postulated correlation between galaxy stellar mass, star formation rate (SFR), and gas-phase metallicity. At its core, this relation posits that offsets from the mass-metallicity relation (MZR) at a fixed stellar mass are correlated with galactic SFR. In this Letter, we use hydrodynamical simulations to quantify the time-scales over which populations of galaxies oscillate about the average SFR and metallicity values at fixed stellar mass. We find that Illustris and IllustrisTNG predict that galaxy offsets from the star formation main sequence and MZR oscillate over similar time-scales, are often anticorrelated in their evolution, evolve with the halo dynamical time, and produce a pronounced FMR. Our models indicate that galaxies oscillate about equilibrium SFR and metallicity values - set by the galaxy's stellar mass - and that SFR and metallicity offsets evolve in an anticorrelated fashion. This anticorrelated variability of the metallicity and SFR offsets drives the existence of the FMR in our models. In contrast to Illustris and IllustrisTNG, we speculate that the SFR and metallicity evolution tracks may become decoupled in galaxy formation models dominated by feedback-driven globally bursty SFR histories, which could weaken the FMR residual correlation strength. This opens the possibility of discriminating between bursty and non-bursty feedback models based on the strength and persistence of the FMR - especially at high redshift.

  8. HIDE-AND-SEEK WITH THE FUNDAMENTAL METALLICITY RELATION

    Energy Technology Data Exchange (ETDEWEB)

    Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 (Japan); Renzini, A. [INAF Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, I-35122 Padova (Italy); Silverman, J. D. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, the University of Tokyo, Kashiwanoha, Kashiwa, 277-8583 (Japan); Daddi, E., E-mail: daichi@nagoya-u.jp [Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/CEA-Saclay, Service d’Astrophysique, F-91191 Gif-sur-Yvette (France)

    2016-06-01

    We use ∼83,000 star-forming galaxies at 0.04 < z < 0.3 from the Sloan Digital Sky Survey to study the so-called fundamental metallicity relation (FMR) and report on the disappearance of its anti-correlation between metallicity and star formation rate (SFR) when using the new metallicity indicator recently proposed by Dopita et al. In this calibration, metallicity is primarily sensitive to the emission line ratio [N ii] λ 6584/[S ii] λλ 6717, 6731 that is insensitive to dilution by pristine infalling gas that may drive the FMR anti-correlation with SFR. Therefore, we conclude that the apparent disappearance of the FMR (using this new metallicity indicator) does not rule out its existence.

  9. Ternary Complexes of some Divalent Metal Ions with Potentially ...

    African Journals Online (AJOL)

    NICO

    -aminobutyric acid.7–9 Calcium and magnesium are essential mineral nutrients for life.10,11 In animals and plants different cell types maintain different concentrations of magne- sium.12–16 The Lewis acidity of the Zn2+ ion, flexibility of its.

  10. ORIGIN OF THE GALAXY MASS-METALLICITY-STAR FORMATION RELATION

    International Nuclear Information System (INIS)

    Harwit, Martin; Brisbin, Drew

    2015-01-01

    We describe an equilibrium model that links the metallicity of low-redshift galaxies to stellar evolution models. It enables the testing of different stellar initial mass functions and metal yields against observed galaxy metallicities. We show that the metallicities of more than 80,000 Sloan Digital Sky Survey galaxies in the low-redshift range 0.07 ≤ z ≤ 0.3 considerably constrain stellar evolution models that simultaneously relate galaxy stellar mass, metallicity, and star formation rates to the infall rate of low-metallicity extragalactic gas and outflow of enriched matter. A feature of our model is that it encompasses both the active star forming phases of a galaxy and epochs during which the same galaxy may lie fallow. We show that the galaxy mass-metallicity-star formation relation can be traced to infall of extragalactic gas mixing with native gas from host galaxies to form stars of observed metallicities, the most massive of which eject oxygen into extragalactic space. Most consequential among our findings is that, on average, extragalactic infall accounts for one half of the gas required for star formation, a ratio that is remarkably constant across galaxies with stellar masses ranging at least from M* = 2 × 10 9 to 6 × 10 10 M ☉ . This leads us to propose that star formation is initiated when extragalactic infall roughly doubles the mass of marginally stable interstellar clouds. The processes described may also account quantitatively for the metallicity of extragalactic space, though to check this the fraction of extragalactic baryons will need to be more firmly established

  11. ORIGIN OF THE GALAXY MASS-METALLICITY-STAR FORMATION RELATION

    Energy Technology Data Exchange (ETDEWEB)

    Harwit, Martin; Brisbin, Drew, E-mail: harwit@verizon.net [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)

    2015-02-20

    We describe an equilibrium model that links the metallicity of low-redshift galaxies to stellar evolution models. It enables the testing of different stellar initial mass functions and metal yields against observed galaxy metallicities. We show that the metallicities of more than 80,000 Sloan Digital Sky Survey galaxies in the low-redshift range 0.07 ≤ z ≤ 0.3 considerably constrain stellar evolution models that simultaneously relate galaxy stellar mass, metallicity, and star formation rates to the infall rate of low-metallicity extragalactic gas and outflow of enriched matter. A feature of our model is that it encompasses both the active star forming phases of a galaxy and epochs during which the same galaxy may lie fallow. We show that the galaxy mass-metallicity-star formation relation can be traced to infall of extragalactic gas mixing with native gas from host galaxies to form stars of observed metallicities, the most massive of which eject oxygen into extragalactic space. Most consequential among our findings is that, on average, extragalactic infall accounts for one half of the gas required for star formation, a ratio that is remarkably constant across galaxies with stellar masses ranging at least from M* = 2 × 10{sup 9} to 6 × 10{sup 10} M {sub ☉}. This leads us to propose that star formation is initiated when extragalactic infall roughly doubles the mass of marginally stable interstellar clouds. The processes described may also account quantitatively for the metallicity of extragalactic space, though to check this the fraction of extragalactic baryons will need to be more firmly established.

  12. Making Sense of Metal Allergy and Hypersensitivity to Metallic Implants in Relation to Hand Surgery.

    Science.gov (United States)

    Christensen, Thomas J; Samant, Shefali A; Shin, Alexander Y

    2017-09-01

    All metals implanted into a biological system undergo some degree of corrosion depending upon its composition. The electrochemical process of corrosion produces free metal ions, which may activate the host's immune system through a variety of mechanisms. Whereas dermal metal hypersensitivity is common, affecting 10% to 15% of the population, the immune reaction from implanted metals is much less common (allergy and hypersensitivity producing a multitude of patient symptoms. Superficial symptoms may be mild to severe forms of dermatitis, urticaria, pruritus, and vasculitis, whereas deep sequelae include metallosis-related pseudotumor, implant loosening, and joint stiffness. Currently, there are clinical tests to evaluate patients for metal hypersensitivity, but there is little agreement regarding the ideal timing and clinical situation prompting the work-up of a patient for a metal allergy or hypersensitivity. An understanding of the epidemiology, etiology, basic science, diagnostic testing, and treatment of patients with suspected metal allergy, as it pertains to the current literature, will aid orthopedic and plastic surgeons of all subspecialties in the management of patients requiring metallic implants. Copyright © 2017 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  13. Creep mechanisms and constitutive relations in pure metals

    International Nuclear Information System (INIS)

    Nix, W.D.

    1979-01-01

    The mechanisms of creep of pure metals is briefly reviewed and divided into two parts: steady state flow mechanisms, and non-steady state flow mechanisms and constitutive relations. Creep by diffusional flow is now reasonably well understood, with theory and experiment in good agreement. The closely related phenomenon of Harper--Dorn creep can also be understood in terms of diffusion between dislocations. Power law creep involves the climb of edge disloctions controlled by lattice self diffusion. Theoretical treatments of this process invariably give a power law exponent of 3. This natural creep law is compared with the data for FCC and BCC metals. It is suggested that diffusion controlled climb is the controlling process in BCC metals at very high temperatures. Stacking fault energy effects may preclude the possibility that creep is controlled entirely by lattice self diffusion in some FCC metals. The subject of power law breakdown is presented as a natural consequence of the transition to low temperature flow phenomena. The role of core diffusion in this transition is briefly discussed. The mechanisms are presented by which pure metals creep at elevated temperatures. While most of this review deals with the mechanisms of steady state flow, some discussion is devoted to creep flow under non-steady state conditions. This topic is discussed in connection with the development of constitutive equations for describing plastic flow in metals

  14. Thermal study of monovalent-divalent phase transition in npBifc-F1TCNQ System

    International Nuclear Information System (INIS)

    Sato, Michiko; Nishio, Yutaka; Kajita, Koji; Mochida, Tomoyuki

    2009-01-01

    In a new molecular solid composed of di-neopentyl-biferrocene (npBifc) and fluorotetracyanoquinodimethane (F 1 TCNQ) 3 , Mochida reported the discovery of a reversible valence transfer that can be regarded as an 'ionic(I)-ionic(II)' phase transfer between the monovalent state (D + A - ) and the divalent state (D 2+ A 2- ). We have studied thermo-dynamical properties of this transformation for this complex using the differential thermal analyses (DTA). We observed a broad excess specific heat with multi-peaks attributed to micro-domain structure over the corresponding temperature range (100-150K) accompanied by temperature hysteresis of 7K. The transition entropy (ΔS) was determined to be 22 ± 2 J/mol-K and almost satisfied a Clausius-Clapeyron relation. These experimental results provide an experimental confirmation of the first order phase transition for the monovalent-divalent transfer. At the transition, we observe that the electronic degrees of freedom remained constant values, while large entropy absorbed crossing from low temperature phase to high temperature one is contributed by the lattice one. We finally estimated the internal energy and concluded that delicate energy valance between Madelung, ionization and affinity energies enable this system to exhibit a temperature induce monovalent-divalent phase transition.

  15. Adsorptive behaviour of mercury on algal biomass: Competition with divalent cations and organic compounds

    International Nuclear Information System (INIS)

    Carro, Leticia; Barriada, Jose L.; Herrero, Roberto; Sastre de Vicente, Manuel E.

    2011-01-01

    Highlights: → Native and protonated macroalga S. muticum are good materials for mercury removal. → Fast kinetic process and high mercury uptakes have been found for those materials. → Diffusion control is the rate limiting step of the process. → Competition effects by organic compounds, inorganic salts and divalent cations were analyzed. → Continuous flow experiments allowed identification of mercury reduction during metal removal. - Abstract: Biosorption processes constitute an effective technique for mercury elimination. Sorption properties of native and acid-treated Sargassum muticum have been studied. Effect of pH, initial mercury concentration and contact time studies provided fundamental information about the sorption process. This information was used as the reference values to analyse mercury sorption under competition conditions. Saline effect has shown little influence in sorption, when only electrostatic modifications took place upon salt addition. On the contrary, if mercury speciation dramatically changed owing to the addition of an electrolyte, such as in the case of chloride salt, very large modifications in mercury sorption were observed. Competition with other divalent cations or organic compounds has shown little or none effect on mercury, indicating that a different mechanism is taking place during the removal of these pollutants. Finally, continuous flow experiments have clearly shown that a reduction process is also taking place during mercury removal. This fact is not obvious to elucidate under batch sorption experiments. Scanning Electron Microscopy analysis of the surface of the materials show deposits of mercury(I) and metallic mercury which is indicative of the reduction process proposed.

  16. Dynamic compressive constitutive relation and shearing instability of metallic neodymium

    International Nuclear Information System (INIS)

    Wang Huanran; Cai Canyuan; Chen Danian; Ma Dongfang; Hou Yanjun; Wu Shanxing

    2011-01-01

    Highlights: → Dynamic constitutive relation of Nd was determined in first compression of SHPB. → Deformation of Nd in multi-compression of SHPB were recorded by high-speed camera. → Constitutive relation of Nd was adjusted in modeling large deformation of Nd. → Results of SDDM investigation of recovered Nd specimens showed shearing fracture. → Shearing instability of Nd was estimated with constitutive relation. - Abstract: Based on static tests on MTS and dynamic tests on split Hopkinson pressure bar (SHPB) during the first loading, this study determined the dynamic compressive constitutive relation of metallic Nd. Based on large deformations of metallic Nd specimens generated by the multi-compressive loadings during SHPB tests, and recorded by a high-speed camera, the results of numerical simulations for SHPB test processes were used to extend the determined constitutive relation from small strain to large strain. The shearing instability strain in dynamic compressive deformations of metallic Nd was estimated with the extended constitutive relation according to the criterion given by Batra and Wei, and was compared with the average strain of recovered specimens.

  17. Solubility of hydrogen in transition metals

    International Nuclear Information System (INIS)

    Lee, H.M.

    1976-01-01

    Correlations exist between the heat of solution of hydrogen and the difference in energy between the lowest lying energy levels of the trivalent d/sup n-1/s electronic configuration and the divalent d/sup n-2/s 2 (or the tetravalent d/sup n/) configuration of the neutral gaseous atoms. The trends observed in the transition metal series are discussed in relation to the number of valence electrons per atom in the transition elements in their metallic and neutral states

  18. Rare metal granites and related rocks of the Ukrainian shield

    Directory of Open Access Journals (Sweden)

    Esipchuk, K.Ye.

    1993-12-01

    Full Text Available Two rare metal leucocratic granites, Perga and Kamennaya complexes, can be distinquished on the Ukrainian shield. The Perga complex consists of medium- and coarse grained, mainly porphyric, biotite, riebeckite and aegirine granites, granite porphyries, microclinites and albitites with rare metal mineralization (genthelvite, phenacite, tantalite, cassiterite and wolframite etc.. Granites from several stocks (up to 30 km2 in the northwestern part of the shield, situated along the fracture zone, restricted the large Korosten pluton of rapakivi granites to the northwest. The age of these granites (Pb-Pb and U-Pb methods on zircon and monazite practically coincide with the age of rapakivi granites being 1750 Ma. Within the Korosten complex of rapakivi granites we consider that zinnwaldite granites, which are characterized by fluorite and topazine mineralization, represent the final phase of pluton. These granites differ from the Perga ones by their low content of rare metals. The Kamennaya Mogila complex lies in the southeastern part of the Ukrainian shield. It consists of biotite and muscovite-biotite, medium- and coarse-grained (also porphyric, and occasionally greisining granites with rare metal mineralization (cassiterite, columbite, molybdenite, wolframite and beryl. Granites form several stocks (5-30 km2 situated 10-30 km to the west-northwest of the South-Kalchik gabbro-syenite-granite pluton. Granitoids in both of these complexes have similar isotopic ages (1800 Ma. Leucocratic subalkaline granites (the Novoyanisol type are known within the pluton itself, occupying an intermediate position between the above mentioned in terms of mineral and geochemical composition. The gabbro-syenite-granite formation of the Nearazov region has a substantial similarity to the anorthosite-rapakivi-granite formation. In this respect the relation of each of them to rare metal granites is rather remarkable. This relation is, most probably, not only spatial, but

  19. The modulation of TRPM7 currents by nafamostat mesilate depends directly upon extracellular concentrations of divalent cations

    Directory of Open Access Journals (Sweden)

    Chen Xuanmao

    2010-12-01

    Full Text Available Abstract Concentrations of extracellular divalent cations (Ca2+ and Mg2+ fall substantially during intensive synaptic transmission as well as during some pathophysiological conditions such as epilepsy and brain ischemia. Here we report that a synthetic serine protease inhibitor, nafamostat mesylate (NM, and several of its analogues, block recombinant TRPM7 currents expressed in HEK293T cells in inverse relationship to the concentration of extracellular divalent cations. Lowering extracellular Ca2+ and Mg2+ also evokes a divalent-sensitive non-selective cation current that is mediated by TRPM7 expression in hippocampal neurons. In cultured hippocampal neurons, NM blocked these TRPM7-mediated currents with an apparent affinity of 27 μM, as well as the paradoxical Ca2+ influx associated with lowering extracellular Ca2+. Unexpectedly, pre-exposure to NM strongly potentiated TRPM7 currents. In the presence of physiological concentrations of extracellular divalent cations, NM activates TRPM7. The stimulating effects of NM on TRPM7 currents are also inversely related to extracellular Ca2+ and Mg2+. DAPI and HSB but not netropsin, blocked and stimulated TRPM7. In contrast, mono-cationic, the metabolites of NM, p-GBA and AN, as well as protease inhibitor leupeptin and gabexate failed to substantially modulate TRPM7. NM thus provides a molecular template for the design of putative modulators of TRPM7.

  20. Divalent Copper as a Major Triggering Agent in Alzheimer's Disease.

    Science.gov (United States)

    Brewer, George J

    2015-01-01

    Alzheimer's disease (AD) is at epidemic proportions in developed countries, with a steady increase in the early 1900 s, and then exploding over the last 50 years. This epidemiology points to something causative in the environment of developed countries. This paper will review the considerable evidence that that something could be inorganic copper ingestion. The epidemic parallels closely the spread of copper plumbing, with copper leached from the plumbing into drinking water being a main causal feature, aided by the increasingly common use of supplement pills containing copper. Inorganic copper is divalent copper, or copper-2, while we now know that organic copper, or copper in foods, is primarily monovalent copper, or copper-1. The intestinal transport system, Ctr1, absorbs copper-1 and the copper moves to the liver, where it is put into safe channels. Copper-2 is not absorbed by Ctr1, and some of it bypasses the liver and goes directly into the blood, where it appears to be exquisitely toxic to brain cognition. Thus, while aggregation of amyloid-β has been postulated to be the cause of AD under current dogma, the great increase in prevalence over the last century appears to be due to ingestion of copper-2, which may be causing the aggregation, and/or increasing the oxidant toxicity of the aggregates. An alternative hypothesis proposes that oxidant stress is the primary injuring agent, and under this hypothesis, copper-2 accumulation in the brain may be a causal factor of the oxidant injury. Thus, irrespective of which hypothesis is correct, AD can be classified, at least in part, as a copper-2 toxicity disease. It is relatively easy to avoid copper-2 ingestion, as discussed in this review. If most people begin avoiding copper-2 ingestion, perhaps the epidemic of this serious disease can be aborted.

  1. Compounds of divalent thulium, neodymium, and dysprosium

    International Nuclear Information System (INIS)

    Bochkarev, M.N.; Fedushkin, I.L.; Trifonov, A.A.; Fagin, A.A.; Kirillov, E.N.

    1998-01-01

    Full text: Judging on the Ln(II)/Ln(III) potentials Tm, Nd, and Dy are the first candidates after Sm, Eu, and Yb for the preparation of Ln(II) compounds. The first molecular Tm(II) derivatives, TmI 2 (DME) 3 (I), has been obtained recently by the reduction of TmI 3 with thulium metal in DME (1,2-dimethoxyethane). The tetrahydrofuran (THF) analogue, TmI 2 (THF) 5 , was synthesized similarly. In the case of TmBI 3 and TmCl 3 the same reaction does not occur. The compound I is inert toward naphthalene, anthracene, phenylacetylene, CpH, (Me 3 Si) 2 NH, 2,4,6-t-Bu 3 C 6 H 2 OH, Cp 2 V, Cp 2 Fe, or Cp 3 Er. The reactions of I with PhOH, Ph 3 COH, 3,6-t-Bu 2 C 6 H 2 (OH) 2 -1,2 (Cat), and calixarene (Cal) produce, Ph 3 COTmI 2 (DME) 2 , (Cat)TmI(DME) 2 , and (Cal)TmI, correspondingly. The attempts to use I for preparation of the other Tm(II) complexes failed. In all cases (reactions with C 10 H 8 Li, CpK, [1,3-(Me 3 Si) 2 C 5 H 3 ]MgCl, and [Cp'-SiMe 2 -Ind']K 2 ) the Tm(III) derivatives (respectively, (C 10 H 8 Tm) 2 C 10 H 8 , Cp 3 Tm, [1,3-(Me 3 Si) 2 C 5 H 3 ] 2 TmCl, and Cp'-SiMe 2 -Ind')TmI) were obtained. The new stable Tm(II) complex, PhOTmI(DME) 2 (II), has been synthesized by the reduction of I with potassium metal in DME. The product was isolated as the green crystals with μ eff 4.6 BM. Unlike TmI 3 , NdI 3 and DyI 3 can not be reduced by metallic neodymium, dysprosium or sodium in DME or THF. Re-investigation of the product formed in the reaction of NdCl 3 with a lack of Li and naphthalene which was claimed before as NdCl 2 (THF) 2 has shown that this is a mixture of Nd(III) naphthalene complexes of the type [(NdCl 2 (THF) 2 ]nC 10 H 8 (n = 4- 7) (III). Nevertheless the product may be used instead of NdCl 2 for the preparation of RNdCl 2 type complexes. The reactions of III with t-BuNCH=CHNBu-t (DAD), PhCH=CHCH=CHPh (DBD), and PhCH=CHPh afford (DAD)NdCl 2 (THF) 2 , (DBD)[NdCl 2 (THF) 2 ] 2 , and (PhCHCHPh)[NdCl 2 ] 2 (THF) 3 , respectively. The iodides of Nd

  2. Implications of the dwarfs spheroidal galaxy mass-metallicity relation

    International Nuclear Information System (INIS)

    Smith, G.H.

    1985-01-01

    The properties of the mass-metallicity relation among dwarf spheroidal galaxies are discussed in terms of a model which assumes that the internal chemical evolution of the dwarf spheroidals was promoted by supernova activity. The model can be used to explain the observed dwarf spheroidal mass-metallicity relation assuming the present mass of these systems M sub s is proportional to their initial masses M as M sub s varies according to a power-law index of exp 7/4. It is inferred from the power-law dependence of M on the proto-cloud radius that the most massive dwarf spheroids were formed from the densest clouds. The observed slope of the mass-metallicity relation for dwarf spheroidal galaxies is found to be significantly different from theoretical estimates of this slope for elliptical galaxies. It is suggested that the difference may imply that spheroidal dwarfs and elliptical galaxies had different formation histories, confirming Kormendy's (1985) observations of differences in the brightness and luminosity trends. 54 references

  3. TSCA Chemical Data Reporting Fact Sheet: Reporting Manufactured Chemical Substances from Metal Mining and Related Activities

    Science.gov (United States)

    This fact sheet provides guidance on the Chemical Data Reporting (CDR) rule requirements related to the reporting of mined metals, intermediates, and byproducts manufactured during metal mining and related activities.

  4. Mechanistic studies on E. coli DNA topoisomerase I: Divalent ion effects

    International Nuclear Information System (INIS)

    Domanico, P.L.; Tse-Dinh, Y.C.

    1991-01-01

    E. coli DNA topoisomerase I catalyzes the hydrolysis of short, single stranded oligodeoxynucleotides. It also forms a covalent protein-DNA complex with negatively supercoiled DNA in the absence of Mg2+ but requires Mg2+ for the relaxation of negatively supercoiled DNA. In this paper we investigate the effects of various divalent metals on catalysis. For the relaxation reaction, maximum enzyme activity plateaus after 2.5 mM Mg2+. However, the rate of cleavage of short oligodeoxynucleotide increased linearly between 0 and 15 mM Mg2+. In the oligodeoxynucleotide cleavage reaction, Ca2+, Mn2+, Co2+, and Zn2+ inhibit enzymatic activity. When these metals are coincubated with Mg2+ at equimolar concentrations, the normal effect of Mg2+ is not detectable. Of these metals, only Ca2+ can be substituted for Mg2+ as a metal cofactor in the relaxation reaction. And when Mg2+ is coincubated with Mn2+, Co2+, or Zn2+ at equimolar concentrations, the normal effect of Mg2+ on relaxation is not detectable. The authors propose that Mg2+ allows the protein-DNA complex to assume a conformation necessary for strand passage and enhance the rate of enzyme turnover

  5. Mass and metallicity scaling relations of high-redshift star-forming galaxies selected by GRBs

    DEFF Research Database (Denmark)

    Arabsalmani, M.; Møller, P.; Perley, D.~A.

    2018-01-01

    -metallicity relation of the general population. It is hard to decide whether this relatively small offset is due to systematic effects or the intrinsic nature of GRB hosts. We also investigate the possibility of using absorption-line metallicity measurements of GRB hosts to study the mass-metallicity relation at high...

  6. Distributions and natural levels of related metals in a trophic pathway

    International Nuclear Information System (INIS)

    Lemons, J.D.

    1976-06-01

    The first objective was to test the hypothesis that metal distributions and trends in organisms are, in part, a function of metal positions in the periodic table in unpolluted ecosystems. The data have shown that large soil crustal abundance differences of related elements (e.g. alkali metals) are proportionately approximated in higher organisms. Concentration factors for related nutritious and nonessential and toxic metals were determined along a trophic pathway. When the concentration factors were reported as the concentration of a particular metal by itself, all metal concentrations increased along the trophic pathway. The second objective of this study was to test the hypothesis that distributions and natural levels of chemically related nonessential and toxic metals can better be known when the metals are reported as a ratio, in ash, of the nonessential or toxic metal to its chemically related nutritious metal (e.g. strontium/calcium) as the metals are transferred through trophic pathways. The data have shown that when this method of reporting metal abundances in trophic levels is used, nonessential and toxic metals are discriminated against, relative to their chemically related nutritious metal, as the metals are transferred through the trophic pathway levels. The third objective was designed to test the hypothesis that surface deposition of toxic metals upon plants influences the trends of metal abundances through trophic pathways. This study indicates that metal pollution in the form of deposition upon plant surfaces bypasses the discrimination mechanisms in plants, and consequently elevates the total body burden in herbivores. It is likely that there is no herbivore defense for this type of metal exposure, because herbivores have probably come to rely, in part, upon the discriminatory mechanism of plants throughout the course of evolutionary history to keep toxic metal burdens low

  7. Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

    Science.gov (United States)

    Rijnaarts, Timon; Huerta, Elisa; van Baak, Willem; Nijmeijer, Kitty

    2017-11-07

    Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg 2+ and Ca 2+ ) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

  8. Effect of illite clay and divalent cations on bitumen recovery

    Energy Technology Data Exchange (ETDEWEB)

    Ding, X. [SNC-Lavalin Inc., Calgary, AB (Canada); Repka, C. [Baker Petrolite Corp., Fort McMurray, AB (Canada); Xu, Z.; Masliyah, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

    2006-12-15

    Nearly 35 per cent of Canada's petroleum needs can be met from the Athabasca oil sands, particularly as conventional sources of petroleum decline. The interactions between bitumen and clay minerals play a key role in the recovery process of bitumen because they affect bitumen aeration. The 2 clays minerals found in various oil sands extraction process streams are kaolinite and illite. In this study, doping flotation tests using deionized water and electrokinetic studies were performed to examine the effect of illite clays on bitumen recovery. The effect of magnesium ions was also examined and compared with calcium ions. This paper also discussed the effects of temperature and tailings water chemistry. The negative effect of illite clay on bitumen recovery was found to be associated with its acidity. Denver flotation cell measurements indicated that the addition of calcium or magnesium ions to the flotation deionized water had only a slight effect on bitumen recovery, but the co-addition of illite clay and divalent cations resulted in a dramatic reduction in bitumen recovery. The effect was more significant at lower process temperature and low pH values. Zeta potential distributions of illite suspensions and bitumen emulsions were measured individually and as a mixture to determine the effect of divalent cations on the interaction between bitumen and illite clay. The presence of 1 mM calcium or magnesium ions in deionized water had a pronounced effect on the interactions between bitumen and illite clay. Slime coating of illite onto bitumen was not observed in zeta potential distribution measurements performed in alkaline tailings water. When tests were conducted using plant recycle water, the combination of illite clay and divalent cations did not have an adverse effect on bitumen recovery. 25 refs., 3 tabs., 15 figs.

  9. Alkaline earth metals

    International Nuclear Information System (INIS)

    Brown, Paul L.; Ekberg, Christian

    2016-01-01

    The beryllium ion has a relatively small ionic radius. As a consequence of this small size, its hydrolysis reactions begin to occur at a relatively low pH. To determine the stability and solubility constants, however, the Gibbs energy of the beryllium ion is required. In aqueous solution calcium, like the other alkaline earth metals, only exists as a divalent cation. The size of the alkaline earth cations increases with increasing atomic number, and the calcium ion is bigger than the magnesium ion. The hydrolysis of barium(II) is weaker than that of strontium(II) and also occurs in quite alkaline pH solutions, and similarly, only the species barium hydroxide has been detected. There is only a single experimental study on the hydrolysis of radium. As with the stability constant trend, it would be expected that the enthalpy of radium would be lower than that of barium due to the larger ionic radius.

  10. Inter-DNA Attraction Mediated by Divalent Counterions

    International Nuclear Information System (INIS)

    Qiu Xiangyun; Andresen, Kurt; Kwok, Lisa W.; Lamb, Jessica S.; Park, Hye Yoon; Pollack, Lois

    2007-01-01

    Can nonspecifically bound divalent counterions induce attraction between DNA strands? Here, we present experimental evidence demonstrating attraction between short DNA strands mediated by Mg 2+ ions. Solution small angle x-ray scattering data collected as a function of DNA concentration enable model independent extraction of the second virial coefficient. As the [Mg 2+ ] increases, this coefficient turns from positive to negative reflecting the transition from repulsive to attractive inter-DNA interaction. This surprising observation is corroborated by independent light scattering experiments. The dependence of the observed attraction on experimental parameters including DNA length provides valuable clues to its origin

  11. Investigation of radiation-chemical behaviour of divalent palladium in perchloric acid solutions

    International Nuclear Information System (INIS)

    Vladimirova, M.V.; Kalinina, S.V.

    1988-01-01

    Gamma-radiolysis of divalent palladium in perchloric acid solutions is studied. Absorption spectra of intermediate palladium compounds formed in the irradiated solution are taken. The analysis of literature data as well as comparative analysis of the absorption spectra obtained under irradiation of palladium (2) perchloric acid solutions with absorption spectra of palladium chlorocomplexes allows to suppose that the mentioned compounds are chlorocomplexes of palladium (2) of different composition depending on HClO 4 concentration in the initial solution and absorbed radiation dose. Radiation-chemical reduction of palladium (2) up to metal is stated to take place in the whole studied range of initial concentrations of components of the system and dose rates. Kinetic dependences of metallic palladium formation are obtained. Values of radiation-chemical yields of metallic palladium formation depending on the initial concentrations of palladium (2) and perchloric acid are given. A mechanism of radiolytic reduction of palladium (2) in the investigated system is suggested based on the experimental data, and a theoretical value of the radiation-chemical yield of palladium (2) reduction being in a good agreement with experimentally found values is calculated

  12. Abductor dysfunction and related sciatic nerve palsy, a new complication of metal-on-metal arthroplasty.

    Science.gov (United States)

    Beaver, Walter B; Fehring, Thomas K

    2012-08-01

    The optimal bearing for use in young patients with hip arthritis remains elusive. Current options include metal-on-cross-linked polyethylene, ceramic-on-cross-linked polyethylene, ceramic on ceramic, and metal on metal. Each of these bearing couples has advantages and disadvantages. Metal-on-metal designs allow the use of large heads that decrease impingement and improve stability. This fact has made this bearing an attractive option for surgeons and patients alike. This case report will illustrate a severe adverse reaction to metal debris with necrosis of soft tissues and subsequent damage to the sciatic nerve. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Divalent thulium triflate. A structural and spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Xemard, Mathieu; Jaoul, Arnaud; Cordier, Marie; Nocton, Gregory [Univ. Paris-Saclay, Palaiseau (France). LCM, Ecole polytechnique, CNRS; Molton, Florian; Duboc, Carole [Grenoble Univ., Saint Martin d' Heres (France). Dept. de Chimie Moleculaire; Cador, Olivier; Le Guennic, Boris [Univ. de Rennes 1 (France). Inst. des Sciences Chimique de Rennes, UMR 6226 CNRS; Maury, Olivier [Univ. Claude Bernard Lyon 1 (France). Lab. de Chimie; Clavaguera, Carine [Univ. Paris-Saclay, Palaiseau (France). LCM, Ecole polytechnique, CNRS; Univ. Paris Sud, Univ. Paris-Saclay, Orsay (France). Lab. de Chimie Physique, CNRS

    2017-04-03

    The first molecular Tm{sup II} luminescence measurements are reported along with rare magnetic, X and Q bands EPR studies. Access to simple and soluble molecular divalent lanthanide complexes is highly sought for small-molecule activation studies and organic transformations using single-electron transfer processes. However, owing to their low stability and propensity to disproportionate, these complexes are hard to synthetize and their electronic properties are therefore almost unexplored. Herein we present the synthesis of [Tm(μ-OTf){sub 2}(dme){sub 2}]{sub n}, a rare and simple coordination compound of divalent thulium that can be seen as a promising starting material for the synthesis of more elaborated complexes. This reactive complex was structurally characterized by X-ray diffraction analysis and its electronic structure has been compared with that of its halide cousin TmI{sub 2}(dme){sub 3}. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Thermal study of monovalent-divalent phase transition in npBifc-F{sub 1}TCNQ System

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Michiko; Nishio, Yutaka; Kajita, Koji [Department of Physics, Faculty of Science, Toho University, Miyama 2-2-1, Funabashi, Chiba, 274-8510 (Japan); Mochida, Tomoyuki, E-mail: nishio@ph.sci.toho-u.ac.j [Department of Chemistry, Faculty of Science, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan)

    2009-03-01

    In a new molecular solid composed of di-neopentyl-biferrocene (npBifc) and fluorotetracyanoquinodimethane (F{sub 1}TCNQ){sub 3}, Mochida reported the discovery of a reversible valence transfer that can be regarded as an 'ionic(I)-ionic(II)' phase transfer between the monovalent state (D{sup +}A{sup -}) and the divalent state (D{sup 2+}A{sup 2-}). We have studied thermo-dynamical properties of this transformation for this complex using the differential thermal analyses (DTA). We observed a broad excess specific heat with multi-peaks attributed to micro-domain structure over the corresponding temperature range (100-150K) accompanied by temperature hysteresis of 7K. The transition entropy (DELTAS) was determined to be 22 +- 2 J/mol-K and almost satisfied a Clausius-Clapeyron relation. These experimental results provide an experimental confirmation of the first order phase transition for the monovalent-divalent transfer. At the transition, we observe that the electronic degrees of freedom remained constant values, while large entropy absorbed crossing from low temperature phase to high temperature one is contributed by the lattice one. We finally estimated the internal energy and concluded that delicate energy valance between Madelung, ionization and affinity energies enable this system to exhibit a temperature induce monovalent-divalent phase transition.

  15. Mitochondrial membranes with mono- and divalent salt: changes induced by salt ions on structure and dynamics

    DEFF Research Database (Denmark)

    Pöyry, Sanja; Róg, Tomasz; Karttunen, Mikko

    2009-01-01

    We employ atomistic simulations to consider how mono- (NaCl) and divalent (CaCl(2)) salt affects properties of inner and outer membranes of mitochondria. We find that the influence of salt on structural properties is rather minute, only weakly affecting lipid packing, conformational ordering......, and membrane electrostatic potential. The changes induced by salt are more prominent in dynamical properties related to ion binding and formation of ion-lipid complexes and lipid aggregates, as rotational diffusion of lipids is slowed down by ions, especially in the case of CaCl(2). In the same spirit, lateral...... diffusion of lipids is slowed down rather considerably for increasing concentration of CaCl(2). Both findings for dynamic properties can be traced to the binding of ions with lipid head groups and the related changes in interaction patterns in the headgroup region, where the binding of Na(+) and Ca(2+) ions...

  16. Relation between heavy metals level in soil and some economic ...

    African Journals Online (AJOL)

    Ekpo

    Soil sample with the depth of (0-15cm), cassava leaves and, ... and P111. The high concentrations of trace metals recorded in the leaves of the plant species may be due to ... average temperature is between 250C and 360C ... the traditional land tenure system and the major crops ..... Historical records of metals pollution.

  17. Method for extracting copper, silver and related metals

    Science.gov (United States)

    Moyer, Bruce A.; McDowell, W. J.

    1990-01-01

    A process for selectively extracting precious metals such as silver and gold concurrent with copper extraction from aqueous solutions containing the same. The process utilizes tetrathiamacrocycles and high molecular weight organic acids that exhibit a synergistic relationship when complexing with certain metal ions thereby removing them from ore leach solutions.

  18. Methods for recovering metals from electronic waste, and related systems

    Science.gov (United States)

    Lister, Tedd E; Parkman, Jacob A; Diaz Aldana, Luis A; Clark, Gemma; Dufek, Eric J; Keller, Philip

    2017-10-03

    A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

  19. THE MASS-METALLICITY RELATION OF GLOBULAR CLUSTERS IN THE CONTEXT OF NONLINEAR COLOR-METALLICTY RELATIONS

    International Nuclear Information System (INIS)

    Blakeslee, John P.; Cantiello, Michele; Peng, Eric W.

    2010-01-01

    Two recent empirical developments in the study of extragalactic globular cluster (GC) populations are the color-magnitude relation of the blue GCs (the 'blue tilt') and the nonlinearity of the dependence of optical GC colors on metallicity. The color-magnitude relation, interpreted as a mass-metallicity relation, is thought to be a consequence of self-enrichment. Nonlinear color-metallicity relations have been shown to produce bimodal color distributions from unimodal metallicity distributions. We simulate GC populations including both a mass-metallicity scaling relation and nonlinear color-metallicity relations motivated by theory and observations. Depending on the assumed range of metallicities and the width of the GC luminosity function (GCLF), we find that the simulated populations can have bimodal color distributions with a 'blue tilt' similar to observations, even though the metallicity distribution appears unimodal. The models that produce these features have the relatively high mean GC metallicities and nearly equal blue and red peaks characteristic of giant elliptical galaxies. The blue tilt is less apparent in the models with metallicities typical of dwarf ellipticals; the narrower GCLF in these galaxies has an even bigger effect in reducing the significance of their color-magnitude slopes. We critically examine the evidence for nonlinearity versus bimodal metallicities as explanations for the characteristic double-peaked color histograms of giant ellipticals and conclude that the question remains open. We discuss the prospects for further theoretical and observational progress in constraining the models presented here and for uncovering the true metallicity distributions of extragalactic GC systems.

  20. EPR of divalent manganese in non-Kramers hosts

    Energy Technology Data Exchange (ETDEWEB)

    Lech, J.; Slezak, A. [Institute of Physics, Technical University of Czestochowa, Czestochowa (Poland)

    1997-12-31

    Various interactions which lead to the observation of sharp EPR spectra of the high half-integer spin impurity Mn{sup 2+} (S=5/2) in paramagnetic hosts with integer spins S=1 and S=2 have been studied. Studies have been carried out on the basis of data extracted from experimental EPR spectra of Mn{sup 2+} in single crystal of divalent nickel Ni{sup 2+} (S=1) and Fe{sup 2+} (S=1) perchlorate hexahydrates. It has been shown that dipolar host-host and host-guest couplings broaden resonance lines of Mn{sup 2+}. Narrowing of the lines in the both crystals can be mainly attributed to the host-guest exchange interactions and quenching of the host spins. 19 refs, 3 figs, 1 tab.

  1. Improving the Performance of Lithium Manganese Phosphate Through Divalent Cation Substitution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Guoying; Richardson, Thomas J.

    2008-03-03

    Highly crystalline samples of LiMnPO{sub 4} and its analogs with partial substitution of Mn by divalent Mg, Cu, Zn, and Ni were prepared by hydrothermal synthesis and characterized by x-ray diffraction and infrared spectroscopy. Chemical oxidation produced two-phase mixtures of the initial phases LiMn{sub (1-y)}M{sub y}PO{sub 4} and the delithiated forms, Li{sub y}Mn{sub (1-y)}M{sub y}PO{sub 4}, all with the olivine structure. The extent of oxidation depended upon the quantity of oxidizing agent used and on the identity of the substituent ions. Mg, Ni and Cu were found to increase the level of delithation relative to that in pure LiMnPO{sub 4}. Mg was also shown to reduce the tendency of the oxidized phase to absorb water.

  2. Improvements in or relating to surface treatment of metals

    International Nuclear Information System (INIS)

    Dearnaley, G.; Hartley, N.E.W.

    1975-01-01

    A method is described for surface treating metals so as to reduce their coefficients of friction. The metal is subjected to bombardment by a beam of ions of dry lubricant material, or material that forms a dry lubricant. The ions should have energies sufficient to cause them to be implanted into the surface region of the metal. The metal may be heated to facilitate assimilation of the ions, and implantation may be enhanced by means of irradiation of the article with radiation of energy sufficient to enhance diffusion of the ions into the article. The dry lubricant ions may comprise Mo + , In + , or Sn + . Where the article is of steel suitable ions are Mo + and S + deposited in the ratio of 1:2. Examples of application of the method are given, using a 500 Kv Cockcroft-Walton accelerator for the implantation. (U.K.)

  3. Metal accumulation by stream bryophytes, related to chemical speciation

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, E. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)], E-mail: et@ceh.ac.uk; Vincent, C.D.; Lawlor, A.J.; Lofts, S. [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP (United Kingdom)

    2008-12-15

    Metal accumulation by aquatic bryophytes was investigated using data for headwater streams of differing chemistry. The Windermere Humic Aqueous Model (WHAM) was applied to calculate chemical speciation, including competitive proton and metal interactions with external binding sites on the plants. The speciation modelling approach gives smaller deviations between observed and predicted bryophyte contents of Cu, Zn, Cd and Pb than regressions based on total filtered metal concentrations. If all four metals, and Ni, are considered together, the WHAM predictions are superior at the 1% level. Optimised constants for bryophyte binding by the trace metals are similar to those for humic substances and simple carboxylate ligands. Bryophyte contents of Na, Mg and Ca are approximately explained by binding at external sites, while most of the K is intracellular. Oxide phases account for some of the Al, and most of the Mn, Fe and Co. - Speciation modelling can be used to interpret the accumulation of Ni, Cu, Zn, Cd and Pb by bryophytes, supporting its use to quantify trace metal bioavailability in the field.

  4. Investigations on the metabolism of metals in decapod crustaceas in relation with moulting cycles and reproduction

    International Nuclear Information System (INIS)

    Martin, J.-L.M.

    1975-07-01

    A study of the metabolism of metals was carried out in decapod crustaceas; it showed that it was subject to cyclic variations during the life of the animals, closely correlated with growth moults. The metabolism of metals was also considered in its relations with reproduction, especially oogenesis and spermatogenesis, and embryonic development. In relation with moult, various factors playing a role on metal metabolism were investigated: role of metals in the organism, fasting and nutrition cycles and biochemical reserves, physico-chemical form of the metal and ultrastructure of uptake surfaces. The histological and histochemical aspects of the uptake of a number of metals were studied as well as inter-metallic and inter-organic relationships [fr

  5. Modulating macrophage polarization with divalent cations in nanostructured titanium implant surfaces

    International Nuclear Information System (INIS)

    Lee, Chung-Ho; Kim, Youn-Jeong; Jang, Je-Hee; Park, Jin-Woo

    2016-01-01

    Nanoscale topographical modification and surface chemistry alteration using bioactive ions are centrally important processes in the current design of the surface of titanium (Ti) bone implants with enhanced bone healing capacity. Macrophages play a central role in the early tissue healing stage and their activity in response to the implant surface is known to affect the subsequent healing outcome. Thus, the positive modulation of macrophage phenotype polarization (i.e. towards the regenerative M2 rather than the inflammatory M1 phenotype) with a modified surface is essential for the osteogenesis funtion of Ti bone implants. However, relatively few advances have been made in terms of modulating the macrophage-centered early healing capacity in the surface design of Ti bone implants for the two important surface properties of nanotopography and and bioactive ion chemistry. We investigated whether surface bioactive ion modification exerts a definite beneficial effect on inducing regenerative M2 macrophage polarization when combined with the surface nanotopography of Ti. Our results indicate that nanoscale topographical modification and surface bioactive ion chemistry can positively modulate the macrophage phenotype in a Ti implant surface. To the best of our knowledge, this is the first demonstration that chemical surface modification using divalent cations (Ca and Sr) dramatically induces the regenerative M2 macrophage phenotype of J774.A1 cells in nanostructured Ti surfaces. In this study, divalent cation chemistry regulated the cell shape of adherent macrophages and markedly up-regulated M2 macrophage phenotype expression when combined with the nanostructured Ti surface. These results provide insight into the surface engineering of future Ti bone implants that are harmonized between the macrophage-governed early wound healing process and subsequent mesenchymal stem cell-centered osteogenesis function. (paper)

  6. Modulating macrophage polarization with divalent cations in nanostructured titanium implant surfaces

    Science.gov (United States)

    Lee, Chung-Ho; Kim, Youn-Jeong; Jang, Je-Hee; Park, Jin-Woo

    2016-02-01

    Nanoscale topographical modification and surface chemistry alteration using bioactive ions are centrally important processes in the current design of the surface of titanium (Ti) bone implants with enhanced bone healing capacity. Macrophages play a central role in the early tissue healing stage and their activity in response to the implant surface is known to affect the subsequent healing outcome. Thus, the positive modulation of macrophage phenotype polarization (i.e. towards the regenerative M2 rather than the inflammatory M1 phenotype) with a modified surface is essential for the osteogenesis funtion of Ti bone implants. However, relatively few advances have been made in terms of modulating the macrophage-centered early healing capacity in the surface design of Ti bone implants for the two important surface properties of nanotopography and and bioactive ion chemistry. We investigated whether surface bioactive ion modification exerts a definite beneficial effect on inducing regenerative M2 macrophage polarization when combined with the surface nanotopography of Ti. Our results indicate that nanoscale topographical modification and surface bioactive ion chemistry can positively modulate the macrophage phenotype in a Ti implant surface. To the best of our knowledge, this is the first demonstration that chemical surface modification using divalent cations (Ca and Sr) dramatically induces the regenerative M2 macrophage phenotype of J774.A1 cells in nanostructured Ti surfaces. In this study, divalent cation chemistry regulated the cell shape of adherent macrophages and markedly up-regulated M2 macrophage phenotype expression when combined with the nanostructured Ti surface. These results provide insight into the surface engineering of future Ti bone implants that are harmonized between the macrophage-governed early wound healing process and subsequent mesenchymal stem cell-centered osteogenesis function.

  7. Effect of divalent impurities on some physical properties of LiF and NaF

    International Nuclear Information System (INIS)

    Laj, C.

    1969-05-01

    The ionic thermo-currents technique is applied to the study of impurity vacancy dipoles in LiF and NaF doped with several divalent cations. In LiF only one ITC band is observed whatever the impurity studied. In NaF on the contrary two ITC bands are present, one corresponding to the one observed in LiF, the other one, intense in the case of small impurities, at lower temperature. A parallel EPR study in the case of Mn 2+ doped samples shows that the band observed in LiF and the corresponding one in NaF are due to the relaxation of dipoles formed by the association of an impurity and a vacancy in the next nearest position. The knowledge of the properties of the dipoles allows to show that the room temperature ionic conductivity of LiF is conditioned by the equilibrium: M ++ □+ → M ++ + □+. It is also shown that the isolated cation vacancy originating from this dissociation is responsible for the enhancement of γ-ray coloration of LiF doped with divalent cation impurities. A paramagnetic center ascribed to the presence of Mn 0 isolated in the lattice is also studied. The value of the hyperfine interaction and its temperature dependence are in good agreement with both the theory and the other experimental results. Finally it is shown that the disappearance of dipoles by annealing is related to the formation of complexes involving OH - ions, probably of the M(OH) 2 type, with the two OH - ions occupying a single fluorine site. (author) [fr

  8. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Jie [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Zhao, Changpo [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Luo, Yupeng [Department of Mathematics and Statistics, Auburn University, Auburn, AL 36849 (United States); Liu, Chunsheng, E-mail: liuchunshengidid@126.com [College of Fisheries, Huazhong Agricultural University, Wuhan 430070 (China); Kyzas, George Z. [Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Luo, Yin [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhao, Dongye [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); An, Shuqing [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhu, Hailiang, E-mail: zhuhl@nju.edu.cn [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China)

    2014-04-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD{sub Mn} in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community.

  9. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    International Nuclear Information System (INIS)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z.; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-01-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD Mn in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community

  10. Alkyl, hydride, and related bis(trimethylsilyl)-amide derivatines of the 4f- and 5f-block metals

    International Nuclear Information System (INIS)

    Andersen, R.A.

    1979-12-01

    Physical properties (magnetic susceptibility, NMR, crystal structure, etc.) are reviewed for trivalent lanthanide/actinide derivatives, divalent lanthanide derivatives, and tetravalent actinide derivatives

  11. Rational design of mesoporous metals and related nanomaterials by a soft-template approach.

    Science.gov (United States)

    Yamauchi, Yusuke; Kuroda, Kazuyuki

    2008-04-07

    We review recent developments in the preparation of mesoporous metals and related metal-based nanomaterials. Among the many types of mesoporous materials, mesoporous metals hold promise for a wide range of potential applications, such as in electronic devices, magnetic recording media, and metal catalysts, owing to their metallic frameworks. Mesoporous metals with highly ordered networks and narrow pore-size distributions have traditionally been produced by using mesoporous silica as a hard template. This method involves the formation of an original template followed by deposition of metals within the mesopores and subsequent removal of the template. Another synthetic method is the direct-template approach from lyotropic liquid crystals (LLCs) made of nonionic surfactants at high concentrations. Direct-template synthesis creates a novel avenue for the production of mesoporous metals as well as related metal-based nanomaterials. Many mesoporous metals have been prepared by the chemical or electrochemical reduction of metal salts dissolved in aqueous LLC domains. As a soft template, LLCs are more versatile and therefore more advantageous than hard templates. It is possible to produce various nanostructures (e.g., lamellar, 2D hexagonal (p6mm), and 3D cubic (Ia\\3d)), nanoparticles, and nanotubes simply by controlling the composition of the reaction bath.

  12. Volcano Relation for the Deacon Process over Transition-Metal Oxides

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Hansen, Heine Anton

    2010-01-01

    We establish an activity relation for the heterogeneous catalytic oxidation of HCI (the Deacon Process) over rutile transition-metal oxide catalysts by combining density functional theory calculations (DFT) with microkinetic modeling. Linear energy relations for the elementary reaction steps...

  13. The risk of cataract in relation to metal arc welding

    DEFF Research Database (Denmark)

    Slagor, Rebekka Michaelsen; Dornonville de la Cour, Morten; Bonde, Jens Peter

    2016-01-01

    .95–1.21] and the adjusted HR was 1.08 (95% CI 0.95–1.22). Age and diabetes were as expected strong risk factors. Conclusion: We found no increased risk of developing cataract among Danish metal welders who worked with arc welding from 1950–1985. This may be attributed to the effectiveness of personal safety equipment....... increases the risk of cataract. Method: We compared the risk of being diagnosed with cataract from 1987–2012 in a historic cohort of 4288 male metal arc welders against a reference group comprised of Danish skilled and unskilled male workers with similar age distribution. For the welders’ cohort...... adjusted for baseline data regarding age, diabetes, and social group. Results: There were 266 welders and 29 007 referents with a diagnosis and/or operation for cataract. The unadjusted HR for cataract comparing ever-welders with referents was 1.07 [95% confidence interval (95% CI) 0...

  14. Relations between age, metallicity and kinematics of F-G stars of the Galactic disk

    International Nuclear Information System (INIS)

    Shevelev, Yu.G.; Marsakov, V.A.; Suchkov, A.A.

    1989-01-01

    The data for ∼ 5500 F-G stars are used to study their kinematics, metal abindance and HR diagram in terms of uvby photometry. The age-metallicity, velocity-metallicity, and age-velocity relations are derived. An estimate for the age of the galactic disk is obtained. The following is shown: 1) At[Fe/H] -0.1, turn out to be kinematically younger than these G dwarfs. The same paradox is revealed by G and K giants

  15. Heavy metals in surface sediments of the Jialu River, China: their relations to environmental factors.

    Science.gov (United States)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-04-15

    This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Adiabatic differential scanning calorimetric study of divalent cation induced DNA - DPPC liposome formulation compacted for gene delivery

    Directory of Open Access Journals (Sweden)

    Erhan Süleymanoglu

    2004-11-01

    Full Text Available Complexes between nucleic acids and phospholipid vesicles have been developed as stable non-viral gene delivery vehicles. Currently employed approach uses positively charged lipid species and a helper zwitterionic lipid, the latter being applied for the stabilization of the whole complex. However, besides problematic steps during their preparation, cationic lipids are toxic for cells. The present work describes some energetic issues pertinent to preparation and use of neutral lipid-DNA self-assemblies, thus avoiding toxicity of lipoplexes. Differential scanning calorimetry data showed stabilization of polynucleotide helix upon its interaction with liposomes in the presence of divalent metal cations. It is thus possible to suggest this self-assembly as an improved formulation for use in gene delivery.

  17. NMR determination of chemically related metals in solution as a new method of inorganic analysis

    International Nuclear Information System (INIS)

    Fedorov, L.A.

    1989-01-01

    An NMR spectroscopic method for the determination of chemically related metals in solution is suggested. The metals are determined in complexes with specially selected polydentate ligands. Structural requirements to ligands, analytical properties and general limits of the application of the method are discussed. (orig.)

  18. The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies

    OpenAIRE

    Kirby, Evan N.; Cohen, Judith G.; Guhathakurta, Puragra; Cheng, Lucy; Bullock, James S.; Gallazzi, Anna

    2013-01-01

    We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same massmetallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z * σ M * 0.30±0. 02 . The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar massstellar metallicity relation for galaxies as massive asM*...

  19. Nonlinear Color–Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sooyoung; Yoon, Suk-Jin, E-mail: sjyoon0691@yonsei.ac.kr [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2017-07-01

    Spectroscopy on the globular cluster (GC) system of NGC 5128 revealed bimodality in absorption-line index distributions of its old GCs. GC division is a widely observed and studied phenomenon whose interpretation has depicted host galaxy formation and evolution such that it harbors two distinct metallicity groups. Such a conventional view of GC bimodality has mainly been based on photometry. The recent GC photometric data, however, presented an alternative perspective in which the nonlinear metallicity-to-color transformation is responsible for color bimodality of GC systems. Here we apply the same line of analysis to the spectral indices and examine the absorption-line index versus metallicity relations for the NGC 5128 GC system. NGC 5128 GCs display nonlinearity in the metallicity-index planes, most prominently for the Balmer lines and by a non-negligible degree for the metallicity-sensitive magnesium line. We demonstrate that the observed spectroscopic division of NGC 5128 GCs can be caused by the nonlinear nature of the metallicity-to-index conversions and thus one does not need to resort to two separate GC subgroups. Our analysis incorporating this nonlinearity provides a new perspective on the structure of NGC 5128's GC system, and a further piece to the global picture of the formation of GC systems and their host galaxies.

  20. Superconductivity of divalent Chevrel phases at very high pressures

    International Nuclear Information System (INIS)

    Yao, Y.S.; Guertin, R.P.; Hinks, D.G.; Jorgensen, J.; Capone II, D.W.

    1988-01-01

    The electrical resistivity and the superconducting transition temperatures were examined for three representative divalent Chevrel phase systems, SnMo 6 S 8 , EuMo 6 S 8 , and BaMo 6 S 8 , as a function of hydrostatic pressure to 2 GPa and in quasihydrostatic pressures to 10 GPa. In all systems, T/sub c/ is depressed to 0 K for sufficiently large pressures. For the Sn- and Eu-based systems, both highly purified samples and samples with controlled oxygen content were used. In an oxygenated SnMo 6 S 8 sample (less than 3% O 2 substituted for the S atoms) the pressure threshold and maximum T/sub c/ are 40% lower than in the pure sample, but for P>3.5 GPa the T/sub c/-P phase diagrams nearly coincide, with T/sub c/ reaching zero at an extrapolated pressure of about 12 GPa. In pure EuMo 6 S 8 , superconductivity appears only above a threshold pressure of about 1 GPa and is depressed to 0 K above 4.5 GPa. In an oxygenated sample the maximum T/sub c/ and the threshold pressure are depressed, and above about 3.5 GPa the T/sub c/-P phase diagrams coincide, as in the Sn-based system, although T/sub c/ is then rapidly depressed to 0 K at about 4.5 GPa. In a highly purified BaMo 6 S 8 sample superconductivity appears above about 2 GPa and is depressed to 0 K at extrapolated pressures above 12 GPa. A full transition to the zero-resistance superconducting state is observed in BaMo 6 S 8 . The data are discussed in terms of a model linking the rhombohedral-to-triclinic structural transition, the superconducting transition temperature, and the role of pressure in suppressing the structural transition

  1. On the Origin of the Mass-Metallicity Relation for GRB Host Galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Kocevski, Daniel; /KIPAC, Menlo Park; West, Andrew A.; /Boston U., Dept. Astron.

    2011-06-02

    We investigate the nature of the mass-metallicity (M-Z) relation for long gamma-ray burst (LGRB) host galaxies. Recent studies suggest that the M-Z relation for local LGRB host galaxies may be systematically offset towards lower metallicities relative to the M-Z relation defined by the general star forming galaxy (SDSS) population. The nature of this offset is consistent with suggestions that low metallicity environments may be required to produce high mass progenitors, although the detection of several GRBs in high-mass, high-metallicity galaxies challenges the notion of a strict metallicity cut-off for host galaxies that are capable of producing GRBs. We show that the nature of this reported offset may be explained by a recently proposed anti-correlation between the star formation rate (SFR) and the metallicity of star forming galaxies. If low metallicity galaxies produce more stars than their equally massive, high-metallicity counterparts, then transient events that closely trace the SFR in a galaxy would be more likely to be found in these low metallicity, low mass galaxies. Therefore, the offset between the GRB and SDSS defined M-Z relations may be the result of the different methods used to select their respective galaxy populations, with GRBs being biased towards low metallicity, high SFR, galaxies. We predict that such an offset should not be expected of transient events that do not closely follow the star formation history of their host galaxies, such as short duration GRBs and SN Ia, but should be evident in core collapse SNe found through upcoming untargeted surveys.

  2. [Investigation and analysis of heavy metal pollution related to soil-Panax notoginseng system].

    Science.gov (United States)

    Chen, Lu; Mi, Yan-Hua; Lin, Xin; Liu, Da-Hui; Zeng, Min; Chen, Xiao-Yan

    2014-07-01

    In this study, five heavy metals contamination of soil and different parts of Panax notoginseng in the plantation area was investigated. Analysis of heavy metals correlation between the planting soil and P. notoginseng; and the absorption and accumulation characteristics and translocation of soil heavy metals by P. notoginseng plants was revealed. Through field investigation and laboratory analytical methods, analysis of China's 30 different soil P. notoginseng origin and content of heavy metals in five different parts of the P. notoginseng plant content of heavy metals. The results revealed that the soil heavy metals should not be neglected in the plantation area Referring to the national soil quality standards (GB15608-1995), the excessive degree of soil heavy metals pollution showed Hg > As > Cd > Cr in the plantation area, and Pb content of soil was in the scope of the standard. Refer to 'Green Industry Standards for Import and Export of Medical Plants and Preparations', the excessive degree of heavy metals content of P. notoginseng plants showed As > Pb > Cr > Cd, and Hg content of plants was in the scope of the standard. Concentrations of five heavy metals of underground parts of P. notoginseng plants are higher than aboveground, and heavy metals elements are more concentrated in the root, followed by the rhizome of P. notoginseng plants. Heavy metal accumulation characteristics of the different parts of the P. notoginseng of the overall performance is the root > the rhizome > the root tuber > leaves > stems. From the point of view BCF value analysis of various parts of the P. notoginseng plants to absorb heavy metals in soil, BCF values of all samples were less than 1, description P. notoginseng not belong Hyperaccumulator. From the view of transportation and related analysis of the soil-P. notoginseng systems, the rhizome of P. notoginseng and the content of As and Cr in soil was significantly correlated, the root of P. notoginseng and the content of Cd in

  3. Hotspot related plasmon assisted multiphoton photocurrents in metal-insulator-metal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Differt, Dominik; Pfeiffer, Walter [Universitaet Bielefeld, Universitaetsstr. 25, 33615 Bielefeld (Germany); Diesing, Detlef [Universitaet Duisburg-Essen, Universitaetsstr. 5, 45117 Essen (Germany)

    2011-07-01

    Scanning photocurrent microscopy of metal-insulator-metal junctions (MIM) is used to investigate the mechanisms of femtosecond multiphoton photocurrent injection at liquid nitrogen temperature. The locally induced multiphoton photocurrent in a Ag-TaO-Ta MIM junction is measured in a scanning microscope cryostat under focused illumination (5{mu}m focus diameter, 800 nm, 30 fs, 80 MHz repetition rate). The intensity dependence reveals a mixture of two-photon and three-photon processes that are responsible for the photocurrent. Its lateral variation shows hotspot-like behaviour with significant magnitude variations on a 100 to 200 nm length scale. Assuming an injection current duration of 40fs the peak injection current density of about 10{sup 4} A cm{sup -2} is estimated - 10{sup 6} times higher than that for 400 nm continuous wave illumination slightly below the damage threshold. The simultaneously measured extinction of the incident radiation reveals a 20 to 30% increased absorption at the hotspots. We attribute the local photocurrent enhancement to the defect-assisted excitation of surface plasmon polaritons at the silver electrode leading to an enhanced local excitation.

  4. THE MASS-METALLICITY RELATION WITH THE DIRECT METHOD ON STACKED SPECTRA OF SDSS GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Brett H.; Martini, Paul, E-mail: andrews@astronomy.ohio-state.edu [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States)

    2013-03-10

    The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of {approx}200,000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [O III] {lambda}4363 and [O II] {lambda}{lambda}7320, 7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M{sub *}/M{sub Sun }) = 7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H {proportional_to} M{sub *} {sup 1/2}) until it turns over at log(M{sub *}/M{sub Sun }) = 8.9 and asymptotes to 12 + log(O/H) = 8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.

  5. Relation between tobacco trace metals and soil type in Lebanon

    International Nuclear Information System (INIS)

    SLIM, K.; Saad, Z.; Kazpard, V.; El Samarani, A; Nabhan, Ph.

    2006-01-01

    The aim of study was to determine the concentration of nutrients in soil and tobacco samples from different agricultural regions. We studied the influence of soil type on tobacco quality and the transfer and accumulation of trace metals in tobacco leaves. The results showed that human activities in the Nabatiyeh region had a none pronounced effect on one agricultural plot than on its neighbor. The transfer factor of elements between soil and tobacco plants showed that major constituents are leached and absorbed from the soil, whereas some trace elements are finely absorbed from the alkaline soil. Statistical analysis of the micro nutrients in soil and plants confirmed the existence of two principal factors that control the distribution of elements in different compartments. Four tobacco plots in different regions were also studied as a functions of their pedologic and geologic characteristics. The major elements varied in all regions, but were always ordered Ca > Mg > Na > K. The highest transfer factor for nutrients was found in young soil layers. In the Akkar region, clay nutrients form complexes with micronutrients. Thereby reducing their absorption by tobacco plants. (author)

  6. IMF–METALLICITY: A TIGHT LOCAL RELATION REVEALED BY THE CALIFA SURVEY

    International Nuclear Information System (INIS)

    Martín-Navarro, Ignacio; Vazdekis, Alexandre; Falcón-Barroso, Jesús; La Barbera, Francesco; Lyubenova, Mariya; Trager, S. C.; Ven, Glenn van de; Ferreras, Ignacio; Sánchez, S. F.; García-Benito, R.; Mendoza, M. A.; Mast, D.; Sánchez-Blázquez, P.

    2015-01-01

    Variations in the stellar initial mass function (IMF) have been invoked to explain the spectroscopic and dynamical properties of early-type galaxies (ETGs). However, no observations have yet been able to disentangle the physical driver. We analyze here a sample of 24 ETGs drawn from the CALIFA survey, deriving in a homogeneous way their stellar population and kinematic properties. We find that the local IMF is tightly related to the local metallicity, becoming more bottom-heavy toward metal-rich populations. Our result, combined with the galaxy mass–metallicity relation, naturally explains previous claims of a galaxy mass–IMF relation, derived from non-IFU spectra. If we assume that—within the star formation environment of ETGs—metallicity is the main driver of IMF variations, a significant revision of the interpretation of galaxy evolution observables is necessary

  7. The Impact Of Integrated Parameters In The Manga Local Mass-Metallicity Relation

    Science.gov (United States)

    Barrera-Ballesteros, Jorge K.

    2016-09-01

    We present the surface mass density - gas metallicity (Σ_*-Z) relation for more than 500,000 spatially-resolved star-forming regions from a sample of 617 disk galaxies included in the MaNGA survey. We find a tight relation between these local properties with higher metallicities as the surface density increases, resembling a scaled-down version of the relation found previously for their integrated counterparts. This relation expands over three orders of magnitude in the surface mass and a factor of 8 in metallicity. Our large sample allows us to study the impact of global properties in this local relation. In particular, we find that for most disk galaxies the Σ_*-Z relation does not depend on the total stellar mass. Even more, for a large fraction of our sample (log(M_*/M_{⊙}) > 9.2) the observed metallicity gradients are well reproduced by the mass density gradients and the Σ_*-Z relation. We also find that this relation does not change significantly within the range of redshifts span by our sample. Our results suggest as the predominant scenario for metal enrichment as gas been recycled locally at shorter timescales in comparison to other global processes such as gas accretion or outflows.

  8. Investigation of metal/carbon-related materials for fuel cell applications by electronic structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Ki-jeong [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of)]. E-mail: kong@krict.re.kr; Choi, Youngmin [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Ryu, Beyong-Hwan [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Lee, Jeong-O [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of); Chang, Hyunju [Korea Research Institute of Chemical Technology, P.O.Box 107, Yuseong, Daejeon 305-600 (Korea, Republic of)

    2006-07-15

    The potential of carbon-related materials, such as carbon nanotubes (CNTs) and graphite nanofibers (GNFs), supported metal catalysts as an electrode for fuel cell application was investigated using the first-principle electronic structure calculations. The stable binding geometries and energies of metal catalysts are determined on the CNT surface and the GNF edge. The catalyst metal is more tightly bound to the GNF edge than to the CNT surface because of the existence of active dangling bonds of edge carbon atoms. The diffusion barrier of metal atoms on the surface and edge is also obtained. From our calculation results, we have found that high dispersity is achievable for GNF due to high barrier against the diffusion of metal atoms, while CNT appears less suitable. The GNF with a large edge-to-wall ratio is more suitable for the high-performance electrode than perfect crystalline graphite or CNT.

  9. Investigation of metal/carbon-related materials for fuel cell applications by electronic structure calculations

    International Nuclear Information System (INIS)

    Kong, Ki-jeong; Choi, Youngmin; Ryu, Beyong-Hwan; Lee, Jeong-O; Chang, Hyunju

    2006-01-01

    The potential of carbon-related materials, such as carbon nanotubes (CNTs) and graphite nanofibers (GNFs), supported metal catalysts as an electrode for fuel cell application was investigated using the first-principle electronic structure calculations. The stable binding geometries and energies of metal catalysts are determined on the CNT surface and the GNF edge. The catalyst metal is more tightly bound to the GNF edge than to the CNT surface because of the existence of active dangling bonds of edge carbon atoms. The diffusion barrier of metal atoms on the surface and edge is also obtained. From our calculation results, we have found that high dispersity is achievable for GNF due to high barrier against the diffusion of metal atoms, while CNT appears less suitable. The GNF with a large edge-to-wall ratio is more suitable for the high-performance electrode than perfect crystalline graphite or CNT

  10. Synthetic, spectroscopic and structural studies on 4-aminobenzoate complexes of divalent alkaline earth metals: x-ray crystal structures of [[Mg(H2O)6] (4-aba)2].2H2O and [Ca(H2O)2(4-aba)2] (4-aba=4-aminobenzoate)

    International Nuclear Information System (INIS)

    Murugavel, Ramaswamy; Karambelkar, Vivek V.; Anantharaman, Ganapathi

    2000-01-01

    Reactions between MCl 2 .nH 2 O (M = Mg, Ca, Sr, and Ba) and 4-aminobenzoic acid (4-abaH) result in the formation of complexes [(Mg(H 2 O) 6 )(4-aba) 2 ) .2H 2 O (I), [Ca(4-aba) 2 (H2 O ) 2 ] (2), [Sr(4-aba) 2 (H2 O ) 2 ] (3), and [Ba(4-aba) 2 Cl] (4), respectively. The new compounds 1 and 2, as well as the previously reported 3 and 4 form an extended intra- and intermolecular hydrogen bonded network in the solid-state. The compounds have been characterized by elemental analysis, pH measurements, thermogravimetric studies, and IR, NMR, and UV-Vis spectroscopy. The solid state structures of the molecules 1 and 2 have been determined by single crystal x-ray diffraction studies. In the case of magnesium complex 1, the dipositively charged Mg cation is surrounded by six water molecules and the two 4-aminobenzoate ligands show no direct bonding to the metal ion. The calcium ion in 2 is octa-coordinated with direct coordination of the 4-aminobenzoate ligands to the metal ion. The Ca-Ca separation in the polymeric chain of 2 is 3.9047(5) A. (author)

  11. A METALLICITY-SPIN TEMPERATURE RELATION IN DAMPED Lyα SYSTEMS

    International Nuclear Information System (INIS)

    Kanekar, Nissim; Smette, Alain; Briggs, Frank H.; Chengalur, Jayaram N.

    2009-01-01

    We report evidence for an anti-correlation between spin temperature T s and metallicity [Z/H], detected at 3.6σ significance in a sample of 26 damped Lyα absorbers (DLAs) at redshifts 0.09 s = (-0.68 ± 0.17) x [Z/H] + (2.13 ± 0.21) from a linear regression analysis. Our results indicate that the high T s values found in DLAs do not arise from differences between the optical and radio sightlines, but are likely to reflect the underlying gas temperature distribution. The trend between T s and [Z/H] can be explained by the larger number of radiation pathways for gas cooling in galaxies with high metal abundances, resulting in a high cold gas fraction, and hence, a low spin temperature. Conversely, low-metallicity galaxies have fewer cooling routes, yielding a larger warm gas fraction and a high T s . Most DLAs at z > 1.7 have low metallicities, [Z/H] s and [Z/H] is consistent with the presence of a mass-metallicity relation in DLAs, suggested by the tight correlation between DLA metallicity and the kinematic widths of metal lines. Most high-z DLAs are likely to arise in galaxies with low masses (M vir 10.5 M sun ), low metallicities ([Z/H] <-1), and low cold gas fractions.

  12. Structural study of some divalent aluminoborate glasses using ultrasonic and positron annihilation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Saddeek, Yasser B. [Physics Department, Faculty of Science, Al-Azhar University, Assiut (Egypt); Mohamed, Hamdy F.M. [Physics Department, Faculty of Science, El-Minia University, B.O. 61519 El-Minia (Egypt); Azooz, Moenis A. [Glass Research Department, National Research Center, Dokki, Cairo (Egypt)

    2004-07-01

    Positron annihilation lifetime (PAL), ultrasonic techniques, and differential thermal analysis (DTA) were performed to study the structure of some aluminoborate glasses. The basic compositions of these glasses are 50 B{sub 2}O{sub 3}+ 10 Al {sub 2}O {sub 3}+40RO (wt%), where RO is the divalent oxide (MgO, CaO, SrO, and CdO). The ultrasonic data show that the rigidity increases from MgO to CaO then decrease at SrO and again increases at CdO. The glass transition temperature (determined from DTA) decreases from MgO to SrO then increases at CdO. The trend of the thermal properties was attributed to thermal stability. The experimental data are correlated with the internal glass structure and its connectivity. The PAL data show that an inversely correlation between the relative fractional of the open hole volume and the density of the samples. Also, there is a good correlation between the ortho-positronium (o-Ps) lifetime (open hole volume size) and the bulk modulus of the samples (determined from ultrasonic technique). The open volume hole size distribution for the samples shows that the open volume holes expand in size for CaO, SrO, MgO, and CdO, respectively with their distribution function moving to higher volume size. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Structural study of some divalent aluminoborate glasses using ultrasonic and positron annihilation techniques

    International Nuclear Information System (INIS)

    Saddeek, Yasser B.; Mohamed, Hamdy F.M.; Azooz, Moenis A.

    2004-01-01

    Positron annihilation lifetime (PAL), ultrasonic techniques, and differential thermal analysis (DTA) were performed to study the structure of some aluminoborate glasses. The basic compositions of these glasses are 50 B 2 O 3 + 10 Al 2 O 3 +40RO (wt%), where RO is the divalent oxide (MgO, CaO, SrO, and CdO). The ultrasonic data show that the rigidity increases from MgO to CaO then decrease at SrO and again increases at CdO. The glass transition temperature (determined from DTA) decreases from MgO to SrO then increases at CdO. The trend of the thermal properties was attributed to thermal stability. The experimental data are correlated with the internal glass structure and its connectivity. The PAL data show that an inversely correlation between the relative fractional of the open hole volume and the density of the samples. Also, there is a good correlation between the ortho-positronium (o-Ps) lifetime (open hole volume size) and the bulk modulus of the samples (determined from ultrasonic technique). The open volume hole size distribution for the samples shows that the open volume holes expand in size for CaO, SrO, MgO, and CdO, respectively with their distribution function moving to higher volume size. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Structural study of some divalent aluminoborate glasses using ultrasonic and positron annihilation techniques

    Science.gov (United States)

    Saddeek, Yasser B.; Mohamed, Hamdy F. M.; Azooz, Moenis A.

    2004-07-01

    Positron annihilation lifetime (PAL), ultrasonic techniques, and differential thermal analysis (DTA) were performed to study the structure of some aluminoborate glasses. The basic compositions of these glasses are 50 B2O3 + 10 Al2O3 + 40 RO (wt%), where RO is the divalent oxide (MgO, CaO, SrO, and CdO). The ultrasonic data show that the rigidity increases from MgO to CaO then decrease at SrO and again increases at CdO. The glass transition temperature (determined from DTA) decreases from MgO to SrO then increases at CdO. The trend of the thermal properties was attributed to thermal stability. The experimental data are correlated with the internal glass structure and its connectivity. The PAL data show that an inversely correlation between the relative fractional of the open hole volume and the density of the samples. Also, there is a good correlation between the ortho-positronium (o-Ps) lifetime (open hole volume size) and the bulk modulus of the samples (determined from ultrasonic technique). The open volume hole size distribution for the samples shows that the open volume holes expand in size for CaO, SrO, MgO, and CdO, respectively with their distribution function moving to higher volume size.

  15. Degradation of S-nitrosocysteine in vascular tissue homogenates: role of divalent ions.

    Science.gov (United States)

    Kostka, P; Xu, B; Skiles, E H

    1999-04-01

    The objective of the study was to inquire about the mechanism(s) involved in the catabolism of S-nitrosothiols by vascular tissue under in vitro conditions. Incubations of S-nitrosocysteine (CYSNO) or S-nitrosoglutathione (GSNO) with homogenates isolated from porcine aortic smooth muscle resulted in only a marginal depletion of S-nitrosothiols from the reaction mixtures, which became statistically significant at relatively high concentrations of homogenate (> or =300 microg of protein/ml). Degradation of CYSNO (but not GSNO) was found to be potentiated several-fold by millimolar concentrations of either Mg2+ or Ca2+ ions. Under such conditions, the degradation of CYSNO was significantly suppressed by the removal of proteins by ultrafiltration (>80% inhibition) and eliminated completely by the alkylation of thiol groups with 1 mM N-ethylmaleimide. The potentiating effect of divalent ions on the degradation of CYSNO was insensitive to 0.1 mM neocuproine (selective chelator of Cu+ ions), although it was enhanced in the presence of 0.1 mM o-phenanthroline (selective chelator of Fe2+ ions). It is concluded that the degradation of CYSNO by tissue homogenate involves the interaction with protein-bound sulfhydryl groups, which is stimulated by Mg2+ or Ca2+ ions. The potentiating effect of o-phenanthroline suggests that the liberation of the nitrosonium moiety in such a process may be accompanied by its transfer to sulfur center(s) by transient formation of dinitrosyl-iron complexes.

  16. Using scaling relations to understand trends in the catalytic activity of transition metals

    International Nuclear Information System (INIS)

    Jones, G; Bligaard, T; Abild-Pedersen, F; Noerskov, J K

    2008-01-01

    A method is developed to estimate the potential energy diagram for a full catalytic reaction for a range of late transition metals on the basis of a calculation (or an experimental determination) for a single metal. The method, which employs scaling relations between adsorption energies, is illustrated by calculating the potential energy diagram for the methanation reaction and ammonia synthesis for 11 different metals on the basis of results calculated for Ru. It is also shown that considering the free energy diagram for the reactions, under typical industrial conditions, provides additional insight into reactivity trends

  17. THE METALLICITY BIMODALITY OF GLOBULAR CLUSTER SYSTEMS: A TEST OF GALAXY ASSEMBLY AND OF THE EVOLUTION OF THE GALAXY MASS-METALLICITY RELATION

    International Nuclear Information System (INIS)

    Tonini, Chiara

    2013-01-01

    We build a theoretical model to study the origin of the globular cluster metallicity bimodality in the hierarchical galaxy assembly scenario. The model is based on empirical relations such as the galaxy mass-metallicity relation [O/H]-M star as a function of redshift, and on the observed galaxy stellar mass function up to redshift z ∼ 4. We make use of the theoretical merger rates as a function of mass and redshift from the Millennium simulation to build galaxy merger trees. We derive a new galaxy [Fe/H]-M star relation as a function of redshift, and by assuming that globular clusters share the metallicity of their original parent galaxy at the time of their formation, we populate the merger tree with globular clusters. We perform a series of Monte Carlo simulations of the galaxy hierarchical assembly, and study the properties of the final globular cluster population as a function of galaxy mass, assembly and star formation history, and under different assumptions for the evolution of the galaxy mass-metallicity relation. The main results and predictions of the model are the following. (1) The hierarchical clustering scenario naturally predicts a metallicity bimodality in the galaxy globular cluster population, where the metal-rich subpopulation is composed of globular clusters formed in the galaxy main progenitor around redshift z ∼ 2, and the metal-poor subpopulation is composed of clusters accreted from satellites, and formed at redshifts z ∼ 3-4. (2) The model reproduces the observed relations by Peng et al. for the metallicities of the metal-rich and metal-poor globular cluster subpopulations as a function of galaxy mass; the positions of the metal-poor and metal-rich peaks depend exclusively on the evolution of the galaxy mass-metallicity relation and the [O/Fe], both of which can be constrained by this method. In particular, we find that the galaxy [O/Fe] evolves linearly with redshift from a value of ∼0.5 at redshift z ∼ 4 to a value of ∼0.1 at

  18. The Origin of the Relation between Metallicity and Size in Star-forming Galaxies

    Science.gov (United States)

    Sánchez Almeida, J.; Dalla Vecchia, C.

    2018-06-01

    For the same stellar mass, physically smaller star-forming galaxies are also metal richer. What causes the relation remains unclear. The central star-forming galaxies in the EAGLE cosmological numerical simulation reproduce the observed trend. We use them to explore the origin of the relation assuming that the physical mechanism responsible for the anticorrelation between size and gas-phase metallicity is the same in the simulated and the observed galaxies. We consider the three most likely causes: (1) metal-poor gas inflows feeding the star formation (SF) process, (2) metal-rich gas outflows particularly efficient in shallow gravitational potentials, and (3) enhanced efficiency of the SF process in compact galaxies. Outflows (cause 2) and enhanced SF efficiency (cause 3) can be discarded. Metal-poor gas inflows (cause 1) produce the correlation in the simulated galaxies. Galaxies grow in size with time, so those that receive gas later are both metal poorer and larger, giving rise to the observed anticorrelation. As expected within this explanation, larger galaxies have younger stellar populations. We explore the variation with redshift of the relation, which is maintained up to, at least, redshift 8.

  19. Transport of Magnesium by a Bacterial Nramp-Related Gene

    Science.gov (United States)

    Rodionov, Dmitry A.; Freedman, Benjamin G.; Senger, Ryan S.; Winkler, Wade C.

    2014-01-01

    Magnesium is an essential divalent metal that serves many cellular functions. While most divalent cations are maintained at relatively low intracellular concentrations, magnesium is maintained at a higher level (∼0.5–2.0 mM). Three families of transport proteins were previously identified for magnesium import: CorA, MgtE, and MgtA/MgtB P-type ATPases. In the current study, we find that expression of a bacterial protein unrelated to these transporters can fully restore growth to a bacterial mutant that lacks known magnesium transporters, suggesting it is a new importer for magnesium. We demonstrate that this transport activity is likely to be specific rather than resulting from substrate promiscuity because the proteins are incapable of manganese import. This magnesium transport protein is distantly related to the Nramp family of proteins, which have been shown to transport divalent cations but have never been shown to recognize magnesium. We also find gene expression of the new magnesium transporter to be controlled by a magnesium-sensing riboswitch. Importantly, we find additional examples of riboswitch-regulated homologues, suggesting that they are a frequent occurrence in bacteria. Therefore, our aggregate data discover a new and perhaps broadly important path for magnesium import and highlight how identification of riboswitch RNAs can help shed light on new, and sometimes unexpected, functions of their downstream genes. PMID:24968120

  20. Thermodynamics of binding interactions between extracellular polymeric substances and heavy metals by isothermal titration microcalorimetry.

    Science.gov (United States)

    Yan, Peng; Xia, Jia-Shuai; Chen, You-Peng; Liu, Zhi-Ping; Guo, Jin-Song; Shen, Yu; Zhang, Cheng-Cheng; Wang, Jing

    2017-05-01

    Extracellular polymeric substances (EPS) play a crucial role in heavy metal bio-adsorption using activated sludge, but the interaction mechanism between heavy metals and EPS remains unclear. Isothermal titration calorimetry was employed to illuminate the mechanism in this study. The results indicate that binding between heavy metals and EPS is spontaneous and driven mainly by enthalpy change. Extracellular proteins in EPS are major participants in the binding process. Environmental conditions have significant impact on the adsorption performance. Divalent and trivalent cations severely impeded the binding of heavy metal ions to EPS. Electrostatic interaction mainly attributed to competition between divalent cations and heavy metal ions; trivalent cations directly competed with heavy metal ions for EPS binding sites. Trivalent cations were more competitive than divalent cations for heavy metal ion binding because they formed complexing bonds. This study facilitates a better understanding about the interaction between heavy metals and EPS in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Method of microbially producing metal gallate spinel nano-objects, and compositions produced thereby

    Science.gov (United States)

    Duty, Chad E.; Jellison, Jr., Gerald E.; Love, Lonnie J.; Moon, Ji Won; Phelps, Tommy J.; Ivanov, Ilia N.; Kim, Jongsu; Park, Jehong; Lauf, Robert

    2018-01-16

    A method of forming a metal gallate spinel structure that includes mixing a divalent metal-containing salt and a gallium-containing salt in solution with fermentative or thermophilic bacteria. In the process, the bacteria nucleate metal gallate spinel nano-objects from the divalent metal-containing salt and the gallium-containing salt without requiring reduction of a metal in the solution. The metal gallate spinel structures, as well as light-emitting structures in which they are incorporated, are also described.

  2. On the behavior of Brønsted-Evans-Polanyi relations for transition metal oxides

    DEFF Research Database (Denmark)

    Vojvodic, Aleksandra; Vallejo, Federico Calle; Guo, Wei

    2011-01-01

    Versatile Brønsted-Evans-Polanyi (BEP) relations are found from density functional theory for a wide range of transition metal oxides including rutiles and perovskites. For oxides, the relation depends on the type of oxide, the active site, and the dissociating molecule. The slope of the BEP...

  3. Heavy metal content of lichens in relation to distance from a nickel smelter in Sudbury, Ontario

    Energy Technology Data Exchange (ETDEWEB)

    Nieboer, E; Ahmed, H M; Puckett, K J; Richardson, D H.S.

    1972-01-01

    The Sudbury region of Ontario has large deposits of nickel, iron, and copper, and thus a number of smelting plants which produce sulfur dioxide and heavy metal pollution. Since lichens are good indicators of SO/sub 2/ pollution levels, the pattern of heavy metal content in lichen species in the area of a copper smelter in Sudbury was correlated with distance from the smelter to ascertain whether lichens might also be good indicators of the amount of heavy metal fallout. The lichens were analyzed qualitatively and quantitatively. All seven species of lichens contained copper, iron, zinc, nickel, manganese, and lead. Cadmium and cobalt were detected in two species. Neither gold nor silver could be identified in lichen material with the tests used. A pollution model was developed and compared to field results. The simple dilution of the stack effluent was consistent with the fact that the lichen metal content was related to the reciprocal of the distance from the pollution source. The lichens from the area could tolerate simultaneously high concentrations of several heavy metals that are known to be toxic to other plants. The mechanism of metal uptake was not clearly established. The study showed that lichens and other epiphytes are potentially the most useful indicators of heavy metal fallout around industrial plants.

  4. Long-term field metal extraction by Pelargonium: phytoextraction efficiency in relation to plant maturity.

    Science.gov (United States)

    Shahid, Muhammad; Arshad, Muhammad; Kaemmerer, Michel; Pinelli, Eric; Probst, Anne; Baque, David; Pradere, Philippe; Dumat, Camille

    2012-01-01

    The long length of periods required for effective soil remediation via phytoextraction constitutes a weak point that reduces its industrial use. However, these calculated periods are mainly based on short-term and/or hydroponic controlled experiments. Moreover, only a few studies concern more than one metal, although soils are scarcely polluted by only one element. In this scientific context, the phytoextraction of metals and metalloids (Pb, Cd, Zn, Cu, and As) by Pelargonium was measured after a long-term field experiment. Both bulk and rhizosphere soils were analyzed in order to determine the mechanisms involved in soil-root transfer. First, a strong increase in lead phytoextraction was observed with plant maturity, significantly reducing the length of the period required for remediation. Rhizosphere Pb, Zn, Cu, Cd, and As accumulation was observed (compared to bulk soil), indicating metal mobilization by the plant, perhaps in relation to root activity. Moreover, metal phytoextraction and translocation were found to be a function of the metals' nature. These results, taken altogether, suggest that Pelargonium could be used as a multi-metal hyperaccumulator under multi-metal soil contamination conditions, and they also provide an interesting insight for improving field phytoextraction remediation in terms of the length of time required, promoting this biological technique.

  5. Relating metal bioavailability to risk assessment for aquatic species: Daliao River watershed, China

    International Nuclear Information System (INIS)

    Han, Shuping; Zhang, Ying; Masunaga, Shigeki; Zhou, Siyun; Naito, Wataru

    2014-01-01

    The spatial distribution of metal bioavailability (Ni, Cu, Zn, and Pb) was first evaluated within the waters of Daliao River watershed, using the diffusive gradient in thin films (DGT) and chemical equilibrium models. To assess potential risks associated with metal bioavailability, site-specific 95% protection levels (HC5), risk characterizations ratios (RCR) and ratios of DGT-labile/HC5 were derived, using species sensitivity distribution (SSD). The highest bioavailability values for metals were recorded in the main channel of the Daliao River, followed by the Taizi River. Dynamic concentrations predicted by WHAM 7.0 and NICA-Donnan for Cu and Zn agreed well with DGT results. The estuary of the Daliao River was found to have the highest risks related to Ni, Cu, and Zn. The number of sites at risk increased when considering the total toxicity of Ni, Cu, and Zn. - Highlights: • Spatial variation in metal bioavailability within Daliao River watershed was studied. • WHAM 7.0 and NICA-Donnan examined the differences in predicting metal speciation. • Bioavailability values of metals were highest in main channel of the Daliao River. • Site-specific 95% protection levels (HC5)/risk variations were assessed using SSD. • Maximum risks from Ni, Cu, and Zn occurred in the estuary of the Daliao River. - The highest bioavailability values and the highest risks of metals were found in the estuary of the Daliao River

  6. The role of atomic hydrogen in regulating the scatter of the mass-metallicity relation

    Science.gov (United States)

    Brown, Toby; Cortese, Luca; Catinella, Barbara; Kilborn, Virginia

    2018-01-01

    In this paper, we stack neutral atomic hydrogen (H I) spectra for 9720 star-forming galaxies along the mass-metallicity relation. The sample is selected according to stellar mass (109 ≤ M⋆/M⊙ ≤ 1011) and redshift (0.02 ≤ z ≤ 0.05) from the overlap of the Sloan Digital Sky Survey and Arecibo Legacy Fast ALFA survey. We confirm and quantify the strong anticorrelation between H I mass and gas-phase metallicity at fixed stellar mass. Furthermore, we show for the first time that the relationship between gas content and metallicity is consistent between different metallicity estimators, contrary to the weaker trends found with star formation which are known to depend on the observational techniques used to derive oxygen abundances and star formation rates. When interpreted in the context of theoretical work, this result supports a scenario where galaxies exist in an evolving equilibrium between gas, metallicity and star formation. The fact that deviations from this equilibrium are most strongly correlated with gas mass suggests that the scatter in the mass-metallicity relation is primarily driven by fluctuations in gas accretion.

  7. Metal resistance sequences and transgenic plants

    Science.gov (United States)

    Meagher, Richard Brian; Summers, Anne O.; Rugh, Clayton L.

    1999-10-12

    The present invention provides nucleic acid sequences encoding a metal ion resistance protein, which are expressible in plant cells. The metal resistance protein provides for the enzymatic reduction of metal ions including but not limited to divalent Cu, divalent mercury, trivalent gold, divalent cadmium, lead ions and monovalent silver ions. Transgenic plants which express these coding sequences exhibit increased resistance to metal ions in the environment as compared with plants which have not been so genetically modified. Transgenic plants with improved resistance to organometals including alkylmercury compounds, among others, are provided by the further inclusion of plant-expressible organometal lyase coding sequences, as specifically exemplified by the plant-expressible merB coding sequence. Furthermore, these transgenic plants which have been genetically modified to express the metal resistance coding sequences of the present invention can participate in the bioremediation of metal contamination via the enzymatic reduction of metal ions. Transgenic plants resistant to organometals can further mediate remediation of organic metal compounds, for example, alkylmetal compounds including but not limited to methyl mercury, methyl lead compounds, methyl cadmium and methyl arsenic compounds, in the environment by causing the freeing of mercuric or other metal ions and the reduction of the ionic mercury or other metal ions to the less toxic elemental mercury or other metals.

  8. Metal status in human endometrium: Relation to cigarette smoking and histological lesions

    International Nuclear Information System (INIS)

    Rzymski, Piotr; Rzymski, Paweł; Tomczyk, Katarzyna; Niedzielski, Przemysław; Jakubowski, Karol; Poniedziałek, Barbara; Opala, Tomasz

    2014-01-01

    Human endometrium is a thick, blood vessel-rich, glandular tissue which undergoes cyclic changes and is potentially sensitive to the various endogenous and exogenous compounds supplied via the hematogenous route. As recently indicated, several metals including Cd, Pb, Cr and Ni represent an emerging class of potential metalloestrogens and can be implicated in alterations of the female reproductive system including endometriosis and cancer. In the present study, we investigated the content of five metals: Cd, Cr, Ni, Pb and Zn in 25 samples of human endometrium collected from Polish females undergoing diagnostic or therapeutic curettage of the uterine cavity. The overall mean metal concentration (analyzed using microwave induced plasma atomic emission spectrometry MIP-OES) decreased in the following order: Cr>Pb>Zn>Ni>Cd. For the first time it was demonstrated that cigarette smoking significantly increases the endometrial content of Cd and Pb. Concentration of these metals was also positively correlated with years of smoking and the number of smoked cigarettes. Tissue samples with recognized histologic lesions (simple hyperplasia, polyposis and atrophy) were characterized by a 2-fold higher Cd level. No relation between the age of the women and metal content was found. Our study shows that human endometrium can be a potential target of metal accumulation within the human body. Quantitative analyses of endometrial metal content could serve as an additional indicator of potential impairments of the menstrual cycle and fertility. - Highlights: • Cd, Cr, Ni, Pb and Zn are detectable in human endometrium. • Mean metal content in human endometrium decreases in Cr>Pb>Zn>Ni>Cd order. • Cigarettes smoking increases endometrial content of Cd and Pb. • Lesioned endometrial tissue was characterized by higher metal contents

  9. Metal status in human endometrium: Relation to cigarette smoking and histological lesions

    Energy Technology Data Exchange (ETDEWEB)

    Rzymski, Piotr, E-mail: rzymskipiotr@ump.edu.pl [Department of Biology and Environmental Protection, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznań (Poland); Rzymski, Paweł; Tomczyk, Katarzyna [Department of Mother' s and Child' s Health, Gynecologic and Obstetrical University Hospital, Poznan University of Medical Sciences, Poznań (Poland); Niedzielski, Przemysław; Jakubowski, Karol [Department of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań (Poland); Poniedziałek, Barbara [Department of Biology and Environmental Protection, Poznan University of Medical Sciences, Rokietnicka 8, 60-806 Poznań (Poland); Opala, Tomasz [Department of Mother' s and Child' s Health, Gynecologic and Obstetrical University Hospital, Poznan University of Medical Sciences, Poznań (Poland)

    2014-07-15

    Human endometrium is a thick, blood vessel-rich, glandular tissue which undergoes cyclic changes and is potentially sensitive to the various endogenous and exogenous compounds supplied via the hematogenous route. As recently indicated, several metals including Cd, Pb, Cr and Ni represent an emerging class of potential metalloestrogens and can be implicated in alterations of the female reproductive system including endometriosis and cancer. In the present study, we investigated the content of five metals: Cd, Cr, Ni, Pb and Zn in 25 samples of human endometrium collected from Polish females undergoing diagnostic or therapeutic curettage of the uterine cavity. The overall mean metal concentration (analyzed using microwave induced plasma atomic emission spectrometry MIP-OES) decreased in the following order: Cr>Pb>Zn>Ni>Cd. For the first time it was demonstrated that cigarette smoking significantly increases the endometrial content of Cd and Pb. Concentration of these metals was also positively correlated with years of smoking and the number of smoked cigarettes. Tissue samples with recognized histologic lesions (simple hyperplasia, polyposis and atrophy) were characterized by a 2-fold higher Cd level. No relation between the age of the women and metal content was found. Our study shows that human endometrium can be a potential target of metal accumulation within the human body. Quantitative analyses of endometrial metal content could serve as an additional indicator of potential impairments of the menstrual cycle and fertility. - Highlights: • Cd, Cr, Ni, Pb and Zn are detectable in human endometrium. • Mean metal content in human endometrium decreases in Cr>Pb>Zn>Ni>Cd order. • Cigarettes smoking increases endometrial content of Cd and Pb. • Lesioned endometrial tissue was characterized by higher metal contents.

  10. EXPLORING SYSTEMATIC EFFECTS IN THE RELATION BETWEEN STELLAR MASS, GAS PHASE METALLICITY, AND STAR FORMATION RATE

    International Nuclear Information System (INIS)

    Telford, O. Grace; Dalcanton, Julianne J.; Skillman, Evan D.; Conroy, Charlie

    2016-01-01

    There is evidence that the well-established mass–metallicity relation in galaxies is correlated with a third parameter: star formation rate (SFR). The strength of this correlation may be used to disentangle the relative importance of different physical processes (e.g., infall of pristine gas, metal-enriched outflows) in governing chemical evolution. However, all three parameters are susceptible to biases that might affect the observed strength of the relation between them. We analyze possible sources of systematic error, including sample bias, application of signal-to-noise ratio cuts on emission lines, choice of metallicity calibration, uncertainty in stellar mass determination, aperture effects, and dust. We present the first analysis of the relation between stellar mass, gas phase metallicity, and SFR using strong line abundance diagnostics from Dopita et al. for ∼130,000 star-forming galaxies in the Sloan Digital Sky Survey and provide a detailed comparison of these diagnostics in an appendix. Using these new abundance diagnostics yields a 30%–55% weaker anti-correlation between metallicity and SFR at fixed stellar mass than that reported by Mannucci et al. We find that, for all abundance diagnostics, the anti-correlation with SFR is stronger for the relatively few galaxies whose current SFRs are elevated above their past average SFRs. This is also true for the new abundance diagnostic of Dopita et al., which gives anti-correlation between Z and SFR only in the high specific star formation rate (sSFR) regime, in contrast to the recent results of Kashino et al. The poorly constrained strength of the relation between stellar mass, metallicity, and SFR must be carefully accounted for in theoretical studies of chemical evolution.

  11. Time-dependent inelastic analysis of metallic media using constitutive relations with state variables

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, V; Mukherjee, S [Cornell Univ., Ithaca, N.Y. (USA)

    1977-03-01

    A computational technique in terms of stress, strain and displacement rates is presented for the solution of boundary value problems for metallic structural elements at uniform elevated temperatures subjected to time varying loads. This method can accommodate any number of constitutive relations with state variables recently proposed by other researchers to model the inelastic deformation of metallic media at elevated temperatures. Numerical solutions are obtained for several structural elements subjected to steady loads. The constitutive relations used for these numerical solutions are due to Hart. The solutions are discussed in the context of the computational scheme and Hart's theory.

  12. Relation of radiation damage of metallic solids to electronic structure. Pt. 5

    International Nuclear Information System (INIS)

    Shalaev, A.M.; Adamenko, A.A.

    1977-01-01

    The problem of relating a damage in metal solids to the parameters of radiation fluxes and the physical nature of a target is considered. Basing upon experimental and theoretical investigations into the processes of interaction of particle fluxes with solids, the following conclusions have been reached. Threshold energy of ion displacement in the crystal lattice of a metal solid is dependent on the energy of a bombarding particle, which is due to ionization and electroexcitation stimulated by energy transfer from a fast particle to a system of collectivized electrons. The rate of metal solid damage by radiation depends on the state of the crystal lattice, in particular on its defectness. Variations of local electron density in the vicinity of a defect are related with changing thermodynamic characteristics of radiation-induced defect formation. A type of atomic bond in a solid affects the rate of radiation damage. The greatest damage occurs in materials with a covalent bond

  13. Divalent cations as modulators of neuronal excitability: Emphasis on copper and zinc

    Directory of Open Access Journals (Sweden)

    RICARDO DELGADO

    2006-01-01

    Full Text Available Based on indirect evidence, a role for synaptically released copper and zinc as modulators of neuronal activity has been proposed. To test this proposal directly, we studied the effect of copper, zinc, and other divalent cations on voltage-dependent currents in dissociated toad olfactory neurons and on their firing rate induced by small depolarizing currents. Divalent cations in the nanomolar range sped up the activation kinetics and increased the amplitude of the inward sodium current. In the micromolar range, they caused a dose dependent inhibition of the inward Na+ and Ca2+ currents (I Na and I Ca and reduced de amplitude of the Ca2+-dependent K+ outward current (I Ca-K. On the other hand, the firing rate of olfactory neurons increased when exposed to nanomolar concentration of divalent cations and decreased when exposed to micromolar concentrations. This biphasic effect of divalent cations on neuronal excitability may be explained by the interaction of these ions with high and low affinity sites in voltage-gated channels. Our results support the idea that these ions are normal modulators of neuronal excitability

  14. Ab Initio Assessment of the Bonding in Disulfonates Containing Divalent Nitrogen and Phosphorus Atoms

    DEFF Research Database (Denmark)

    Andersen, Vinca Bonde; Berg, Rolf W.; Shim, Irene

    2017-01-01

    The iminodisulfonate, [N(SO3)2]3–, and phosphinodisulfonate, [P(SO3)2]3–, ions have been investigated by performing ab initio MP2/6-311+G**calculations. The nitrogen and phosphorus atoms as part of the ions are shown to be divalent with a negative charge and two lone pairs on the nitrogen...

  15. Mitochondrial membranes with mono- and divalent salt: Changes induced by salt ions on structure and dynamics

    NARCIS (Netherlands)

    Pöyry, S.; Róg, T.; Karttunen, M.E.J.; Vattulainen, I.

    2009-01-01

    We employ atomistic simulations to consider how mono- (NaCl) and divalent (CaCl2) salt affects properties of inner and outer membranes of mitochondria. We find that the influence of salt on structural properties is rather minute, only weakly affecting lipid packing, conformational ordering, and

  16. Effect of divalent (Sr, Ba) doping on the structural and magnetic properties of BiFeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Rangi, Manisha, E-mail: mrangi100@gmail.com; Sanghi, Sujata; Agarwal, Ashish; Jangra, Sandhaya; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar, Haryana- 125001 (India)

    2015-06-24

    The effect of divalent substitution on the crystal structure and magnetic properties of BiFeO{sub 3} has been investigated using X-ray diffraction and magnetic measurements technique. Single phase Bi{sub 0.8}A{sub 0.2}FeO{sub 3} (A= Sr, Ba) multiferroics have been synthesized by solid state reaction method. Rietveld analysis of the XRD patterns revealed that the prepared ceramics exhibit rhombohedral structure with space group R3c. M–H hysteresis loops were recorded at 5K revealed that Sr and Ba substitution transformed antiferromagnetic BiFeO3 into weak ferromagnetic. The enhanced magnetization with Sr and Ba addition is confirmed by the MT curve recorded at 1T. It is closely related to intrinsic structural distortion and modification of the antiparallel spin structure.

  17. Electronic, elastic and optical properties of divalent (R+2X) and trivalent (R+3X) rare earth monochalcogenides

    Science.gov (United States)

    Kumar, V.; Chandra, S.; Singh, J. K.

    2017-08-01

    Based on plasma oscillations theory of solids, simple relations have been proposed for the calculation of bond length, specific gravity, homopolar energy gap, heteropolar energy gap, average energy gap, crystal ionicity, bulk modulus, electronic polarizability and dielectric constant of rare earth divalent R+2X and trivalent R+3X monochalcogenides. The specific gravity of nine R+2X, twenty R+3X, and bulk modulus of twenty R+3X monochalcogenides have been calculated for the first time. The calculated values of all parameters are compared with the available experimental and the reported values. A fairly good agreement has been obtained between them. The average percentage deviation of two parameters: bulk modulus and electronic polarizability for which experimental data are known, have also been calculated and found to be better than the earlier correlations.

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

    Science.gov (United States)

    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.

  19. Accumulation of Heavy Metals in Roadside Soil in Urban Area and the Related Impacting Factors.

    Science.gov (United States)

    Wang, Meie; Zhang, Haizhen

    2018-05-24

    Heavy metal contamination in roadside soil due to traffic emission has been recognized for a long time. However, seldom has been reported regarding identification of critical factors influencing the accumulation of heavy metals in urban roadside soils due to the frequent disturbances such as the repair of damaged roads and green belt maintanance. Heavy metals in the roadside soils of 45 roads in Xihu district, Hangzhou city were investigated. Results suggested the accumulation of Cu, Pb, Cd, Cr, and Zn in roadside soil was affected by human activity. However, only two sites had Pb and Zn excessing the standards for residential areas, respectively, according to Chinese Environmental Quality Standards for soils. The concentrations of Cu, Pb, Cd, and Zn were significantly and positively correlated to soil pH and organic matter. An insignificant correlation between the age of the roads or vegetation cover types and the concentration of heavy metals was found although they were reported closely relating to the accumulation of heavy metals in roadside soils of highways. The highest Pb, Cd, and Cr taking place in sites with heavy traffic and significant differences in the concentrations of Cu, Pb, Cd, and Zn among the different categories of roads suggested the contribution of traffic intensity. However, it was difficult to establish a quantitative relationship between traffic intensity and the concentrations of heavy metals in the roadside soil. It could be concluded that impaction of traffic emission on the accumulation of heavy metals in roadside soils in urban area was slight and soil properties such as pH and organic matters were critical factors influencing the retention of heavy metals in soils.

  20. The relation between Acid Volatile Sulfides (AVS) and metal accumulation in aquatic invertebrates: implications of feeding behavior and ecology.

    Science.gov (United States)

    De Jonge, Maarten; Blust, Ronny; Bervoets, Lieven

    2010-05-01

    The present study evaluates the relationship between Acid Volatile Sulfides (AVS) and metal accumulation in invertebrates with different feeding behavior and ecological preferences. Natural sediments, pore water and surface water, together with benthic and epibenthic invertebrates were sampled at 28 Flemish lowland rivers. Different metals as well as metal binding sediment characteristics including AVS were measured and multiple regression was used to study their relationship with accumulated metals in the invertebrates taxa. Bioaccumulation in the benthic taxa was primarily influenced by total metal concentrations in the sediment. Regarding the epibenthic taxa metal accumulation was mostly explained by the more bioavailable metal fractions in both the sediment and the water. AVS concentrations were generally better correlated with metal accumulation in the epibenthic invertebrates, rather than with the benthic taxa. Our results indicated that the relation between AVS and metal accumulation in aquatic invertebrates is highly dependent on feeding behavior and ecology. Copyright 2010 Elsevier Ltd. All rights reserved.

  1. Influence of Divalent Counterions on the Dynamics in DNA as Probed by Using a Minor-Groove Binder.

    Science.gov (United States)

    Paul, Sneha; Ahmed, Tasnim; Samanta, Anunay

    2017-08-05

    DNA dynamics, to which water, counterions, and DNA motions contribute, is a topic of considerable interest because it is closely related to the efficiency of biological functions performed by it. Simulation studies and experiments suggest that the counterion dynamics in DNA probed by a minor-groove binder are similar for various monovalent counterions. To date, the influence on DNA dynamics of higher-valence counterions, which are also present around DNA and are known to bind more strongly to it than monovalent ions, has not been studied. Herein we investigated DNA dynamics in the presence of Mg 2+ and Ca 2+ , chosen for their relative abundance in cells, by using minor-groove binder 4',6-diamidino-2-phenylindole (DAPI) as a fluorescence probe. The dynamics, as measured from the time-resolved fluorescence Stokes shifts of DAPI bound to calf thymus DNA on a subpicosecond-to-nanosecond timescale, were found to be very similar in the presence of both the divalent ions and Na + ions. The observation is explained by considering the screening of the electric field of the divalent ion by its hydration shell, preferential binding of the ions to the phosphate groups, and displacement of ions from the minor groove by DAPI due to the stronger binding interaction of the latter. Furthermore, the similarity of our results in the presence of Na + to those reported for smaller oligonucleotides suggests that the chain length of DNA does not influence the DNA dynamics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Methanosarcina acetivorans C2A topoisomerase IIIα, an archaeal enzyme with promiscuity in divalent cation dependence.

    Directory of Open Access Journals (Sweden)

    Raymond Morales

    Full Text Available Topoisomerases play a fundamental role in genome stability, DNA replication and repair. As a result, topoisomerases have served as therapeutic targets of interest in Eukarya and Bacteria, two of the three domains of life. Since members of Archaea, the third domain of life, have not been implicated in any diseased state to-date, there is a paucity of data on archaeal topoisomerases. Here we report Methanosarcina acetivorans TopoIIIα (MacTopoIIIα as the first biochemically characterized mesophilic archaeal topoisomerase. Maximal activity for MacTopoIIIα was elicited at 30-35°C and 100 mM NaCl. As little as 10 fmol of the enzyme initiated DNA relaxation, and NaCl concentrations above 250 mM inhibited this activity. The present study also provides the first evidence that a type IA Topoisomerase has activity in the presence of all divalent cations tested (Mg(2+, Ca(2+, Sr(2+, Ba(2+, Mn(2+, Fe(2+, Co(2+, Ni(2+, Cu(2+, Zn(2+ and Cd(2+. Activity profiles were, however, specific to each metal. Known type I (ssDNA and camptothecin and type II (etoposide, novobiocin and nalidixic acid inhibitors with different mechanisms of action were used to demonstrate that MacTopoIIIα is a type IA topoisomerase. Alignment of MacTopoIIIα with characterized topoisomerases identified Y317 as the putative catalytic residue, and a Y317F mutation ablated DNA relaxation activity, demonstrating that Y317 is essential for catalysis. As the role of Domain V (C-terminal domain is unclear, MacTopoIIIα was aligned with the canonical E. coli TopoI 67 kDa fragment in order to construct an N-terminal (1-586 and a C-terminal (587-752 fragment for analysis. Activity could neither be elicited from the fragments individually nor reconstituted from a mixture of the fragments, suggesting that native folding is impaired when the two fragments are expressed separately. Evidence that each of the split domains plays a role in Zn(2+ binding of the enzyme is also provided.

  3. Reactive oxygen species-related activities of nano-iron metal and nano-iron oxides.

    Science.gov (United States)

    Wu, Haohao; Yin, Jun-Jie; Wamer, Wayne G; Zeng, Mingyong; Lo, Y Martin

    2014-03-01

    Nano-iron metal and nano-iron oxides are among the most widely used engineered and naturally occurring nanostructures, and the increasing incidence of biological exposure to these nanostructures has raised concerns about their biotoxicity. Reactive oxygen species (ROS)-induced oxidative stress is one of the most accepted toxic mechanisms and, in the past decades, considerable efforts have been made to investigate the ROS-related activities of iron nanostructures. In this review, we summarize activities of nano-iron metal and nano-iron oxides in ROS-related redox processes, addressing in detail the known homogeneous and heterogeneous redox mechanisms involved in these processes, intrinsic ROS-related properties of iron nanostructures (chemical composition, particle size, and crystalline phase), and ROS-related bio-microenvironmental factors, including physiological pH and buffers, biogenic reducing agents, and other organic substances. Copyright © 2014. Published by Elsevier B.V.

  4. Heavy Metal Content in Chilean Fish Related to Habitat Use, Tissue Type and River of Origin.

    Science.gov (United States)

    Copaja, S V; Pérez, C A; Vega-Retter, C; Véliz, D

    2017-12-01

    In this study, we analyze the concentration of ten metals in two freshwater fish-the benthic catfish Trichomycterus areolatus and the limnetic silverside Basilichthys microlepidotus-in order to detect possible accumulation differences related to fish habitat (benthic or pelagic), tissue type (gill, liver and muscle), and the river of origin (four different rivers) in central Chile. The MANOVA performed with all variables and metals, revealed independent effects of fish, tissue and river. In the case of the fish factor, Cu, Cr, Mo and Zn showed statistically higher concentrations in catfish compared with silverside for all tissues and in all rivers (p food sources and respiration.

  5. Liquid metal embrittlement. From basic concepts to recent results related to structural materials for liquid metal spallation targets

    International Nuclear Information System (INIS)

    Gorse, D.; Goryachev, S.; Auger, T.

    2003-01-01

    At first, the basic features of LME are recalled (definition, characteristics, embrittling couples), together with classical experimental features and open questions. Then, a review of a few very recent results obtained on classical embrittling couples but using new powerful investigation techniques developed in France is proposed. Second we define LMC. The 'LME-LMC' correlation is postulated. Then we concentrate on the LME-LMC problem related to the build-up of the Liquid Metal Spallation target in the frame of the MEGAPIE project. The Russian expertise on LME is briefly mentioned. Then we present some results obtained in the frame of the Groupement de Recherche' GEDEON, focusing on steel grade T91 in contact with lead and lead-bismuth eutectic, in agreement with Russian literature. (author)

  6. Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Achatz, Philipp

    2009-05-15

    During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration n{sub c} for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers ({approx} 500 cm{sup -1}) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance g{sub c}. The granularity also influences significantly the superconducting properties by introducing the superconducting gap {delta} in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the

  7. Metal-insulator transition and superconductivity in heavily boron-doped diamond and related materials

    International Nuclear Information System (INIS)

    Achatz, Philipp

    2009-01-01

    During this PhD project, the metal-insulator transition and superconductivity of highly boron-doped single crystal diamond and related materials have been investigated. The critical boron concentration n c for the metal-insulator transition was found to be the same as for the normal-superconductor transition. All metallic samples have been found to be superconducting and we were able to link the occurence of superconductivity to the proximity to the metal-insulator transition. For this purpose, a scaling law approach based on low temperature transport was proposed. Furthermore, we tried to study the nature of the superconductivity in highly boron doped single crystal diamond. Raman spectroscopy measurements on the isotopically substituted series suggest that the feature occuring at low wavenumbers (∼ 500 cm -1 ) is the A1g vibrational mode associated with boron dimers. Usual Hall effect measurements yielded a puzzling situation in metallic boron-doped diamond samples, leading to carrier concentrations up to a factor 10 higher than the boron concentration determined by secondary ion mass spectroscopy (SIMS). The low temperature transport follows the one expected for a granular metal or insulator, depending on the interplay of intergranular and intragranular (tunneling) conductance. The metal-insulator transition takes place at a critical conductance g c . The granularity also influences significantly the superconducting properties by introducing the superconducting gap Δ in the grain and Josephson coupling J between superconducting grains. A peak in magnetoresistance is observed which can be explained by superconducting fluctuations and the granularity of the system. Additionally we studied the low temperature transport of boron-doped Si samples grown by gas immersion laser doping, some of which yielded a superconducting transition at very low temperatures. Furthermore, preliminary results on the LO-phonon-plasmon coupling are shown for the first time in aluminum

  8. Mitochondrial Dysfunctions and Altered Metals Homeostasis: New Weapons to Counteract HCV-Related Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Mario Arciello

    2013-01-01

    Full Text Available The hepatitis C virus (HCV infection produces several pathological effects in host organism through a wide number of molecular/metabolic pathways. Today it is worldwide accepted that oxidative stress actively participates in HCV pathology, even if the antioxidant therapies adopted until now were scarcely effective. HCV causes oxidative stress by a variety of processes, such as activation of prooxidant enzymes, weakening of antioxidant defenses, organelle damage, and metals unbalance. A focal point, in HCV-related oxidative stress onset, is the mitochondrial failure. These organelles, known to be the “power plants” of cells, have a central role in energy production, metabolism, and metals homeostasis, mainly copper and iron. Furthermore, mitochondria are direct viral targets, because many HCV proteins associate with them. They are the main intracellular free radicals producers and targets. Mitochondrial dysfunctions play a key role in the metal imbalance. This event, today overlooked, is involved in oxidative stress exacerbation and may play a role in HCV life cycle. In this review, we summarize the role of mitochondria and metals in HCV-related oxidative stress, highlighting the need to consider their deregulation in the HCV-related liver damage and in the antiviral management of patients.

  9. Molecular cloning of a putative divalent-cation transporter gene as a new genetic marker for the identification of Lactobacillus brevis strains capable of growing in beer.

    Science.gov (United States)

    Hayashi, N; Ito, M; Horiike, S; Taguchi, H

    2001-05-01

    Random amplified polymorphic DNA (RAPD) PCR analysis of Lactobacillus brevis isolates from breweries revealed that one of the random primers could distinguish beer-spoilage strains of L. brevis from nonspoilage strains. The 1.1-kb DNA fragment amplified from all beer-spoilers included one open reading frame, termed hitA (hop-inducible cation transporter), which encodes an integral membrane protein with 11 putative trans-membrane domains and a binding protein-dependent transport signature of a non-ATP binding membrane transporter common to several prokaryotic and eukaryotic transporters. The hitA polypeptide is homologous to the natural resistance-associated macrophage protein (Nramp) family characterized as divalent-cation transport proteins in many prokaryotic and eukaryotic organisms. Northern blot analysis indicated that the hitA transcripts are expressed in cells cultivated in MRS broth supplemented with hop bitter compounds, which act as mobile-carrier ionophores, dissipating the trans-membrane pH gradient in bacteria sensitive to the hop bitter compounds by exchanging H+ for cellular divalent cations such as Mn2+. This suggests that the hitA gene products may play an important role in making the bacteria resistant to hop bitter compounds in beer by transporting metal ions such as Mn2+ into cells that no longer maintain the proton gradient.

  10. A NEW SCALING RELATION FOR H II REGIONS IN SPIRAL GALAXIES: UNVEILING THE TRUE NATURE OF THE MASS-METALLICITY RELATION

    Energy Technology Data Exchange (ETDEWEB)

    Rosales-Ortega, F. F.; Diaz, A. I. [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Sanchez, S. F.; Iglesias-Paramo, J.; Vilchez, J. M.; Mast, D. [Instituto de Astrofisica de Andalucia (CSIC), Camino Bajo de Huetor s/n, Aptdo. 3004, E-18080 Granada (Spain); Bland-Hawthorn, J. [Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); Husemann, B., E-mail: frosales@cantab.net [Leibniz-Institut fuer Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)

    2012-09-10

    We demonstrate the existence of a local mass, metallicity, star formation relation using spatially resolved optical spectroscopy of H II regions in the local universe. One of the projections of this distribution-the local mass-metallicity relation-extends over a wide range in this parameter space: three orders of magnitude in mass and a factor of eight in metallicity. We explain the new relation as the combined effect of the differential distributions of mass and metallicity in the disks of galaxies, and a selective star formation efficiency. We use this local relation to reproduce-with a noticeable agreement-the mass-metallicity relation seen in galaxies, and conclude that the latter is a scale-up integrated effect of a local relation, supporting the inside-out growth and downsizing scenarios of galaxy evolution.

  11. On the behavior of Bronsted-Evans-Polanyi Relations for Transition Metal Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Vojvodic, Aleksandra

    2011-08-22

    Versatile Broensted-Evans-Polanyi (BEP) relations are found from density functional theory for a wide range of transition metal oxides including rutiles and perovskites. For oxides, the relation depends on the type of oxide, the active site and the dissociating molecule. The slope of the BEP relation is strongly coupled to the adsorbate geometry in the transition state. If it is final state-like the dissociative chemisorption energy can be considered as a descriptor for the dissociation. If it is initial state-like, on the other hand, the dissociative chemisorption energy is not suitable as descriptor for the dissociation. Dissociation of molecules with strong intramolecular bonds belong to the former and molecules with weak intramolecular bonds to the latter group. We show, for the prototype system La-perovskites, that there is a 'cyclic' behavior in the transition state characteristics upon change of the active transition metal of the oxide.

  12. Effect of pH, various divalent metal ion and different substrates on ...

    African Journals Online (AJOL)

    EZUGWU ARINZE LINUS

    2016-05-25

    May 25, 2016 ... Mn2+and Pb2+, however completely inactivated the enzyme. ... exhibits highest activity is called “optimum pH” (Devasena,. 2010). Changes in ... starch was allowed to sediment for 4 h at room temperature. The supernatant was ... Erlenmeyer flask contained 100 ml of sterile cultivation medium optimized for ...

  13. Formation of Layered Double Hydroxides on Alumina Surface in Aqueous Solutions Containing Divalent Metal Cations

    Czech Academy of Sciences Publication Activity Database

    Kovanda, F.; Mašátová, P.; Novotná, P.; Jirátová, Květa

    2009-01-01

    Roč. 57, č. 4 (2009), s. 425-432 ISSN 0009-8604 R&D Projects: GA ČR GA104/07/1400 Institutional research plan: CEZ:AV0Z40720504 Keywords : deposition * layered double hydroxides * supported mixed oxides Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.431, year: 2009

  14. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    DEFF Research Database (Denmark)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouther L.J.

    2013-01-01

    Oxytocin is a peptide drug used to induce labor and prevent bleeding after childbirth. Due to its instability, transport and storage of oxytocin formulations under tropical conditions is problematic. In a previous study, we have found that the stability of oxytocin in aspartate buffered formulati...

  15. "JCE" Classroom Activity #106. Sequestration of Divalent Metal Ion by Superabsorbent Polymer in Diapers

    Science.gov (United States)

    Chen, Yueh-Huey; Lin, Jia-Ying; Lin, Li-Pin; Liang, Han; Yaung, Jing-Fun

    2010-01-01

    This activity explores an alternative use of a superabsorbent polymer known as a water absorbing material. A dilute solution of CuCl[subscript 2] is treated with a small piece of unused disposable diaper containing superabsorbent sodium polyacrylates. The polymer is used for the removal of Cu[superscript 2+] ions from the solution. The…

  16. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation

    NARCIS (Netherlands)

    Avanti, Christina; Oktaviani, Nur Alia; Hinrichs, Wouter L J; Frijlink, Henderik W; Mulder, Frans A A

    2013-01-01

    Oxytocin is a peptide drug used to induce labor and prevent bleeding after childbirth. Due to its instability, transport and storage of oxytocin formulations under tropical conditions is problematic. In a previous study, we have found that the stability of oxytocin in aspartate buffered formulation

  17. The mass-metallicity-star formation rate relation under the STARLIGHT microscope

    Science.gov (United States)

    Schlickmann, M.; Vale Asari, N.; Cid Fernandes, R.; Stasińska, G.

    2014-10-01

    The correlation between stellar mass and gas-phase oxygen abundance (M-Z relation) has been known for decades. The slope and scatter of this trend is strongly dependent on galaxy evolution: Chemical enrichment in a galaxy is driven by its star formation history, which in turn depends on its secular evolution and interaction with other galaxies and intergalactic gas. In last couple of years, the M-Z relation has been studied as a function of a third parameter: the recent star formation rate (SFR) as calibrated by the Hα luminosity, which traces stars formed in the last 10 Myr. This mass-metallicity-SFR relation has been reported to be very tight. This result puts strong constraints on galaxy evolution models in low and high redshifts, informing which models of infall and outflow of gas are acceptable. We explore the mass-metallicity-SFR relation in light of the SDSS-STARLIGHT database put together by our group. We find that we recover similar results as the ones reported by authors who use the MPA/JHU catalogue. We also present some preliminary results exploring the mass-metallicity-SFR relation in a more detailed fashion: starlight recovers a galaxy's full star formation history, and not only its recent SFR.

  18. Origin of metallic Fe-Ni in Renazzo and related chondrites

    Science.gov (United States)

    Lee, Min S.; Rubin, Alan E.; Wasson, John T.

    1992-01-01

    To assess the formation of metallic Fe-Ni in Renazzo and related chondrites, Ni and Co zoning profiles in metallic Fe-Ni are determined from different petrographic sites (chondrule interiors, chondrule margins, chondrule rims, and matrix) in Renazzo, Al Rais, and the related chondrite, MacAlpine Hills 87320. Metal from chondrule interiors shows flat Ni and Co concentrations and profiles, moderately large grain-to-grain compositional variations (even with chondrules), and generally high Ni and Co. Nickel concentrations extend above the kamacite stability limit; etching such 'martensite' shows high-Ni domains in some cases, but observed Ni concentrations do not exceed 190 mg/g. Metal from chondrule margins adjacent to matrix shows convex Ni and Co zoning profiles; the highest Ni and Co concentrations are at grain centers, although the mean central Ni and Co concentrations in margin grains are much lower than those from chondrule interiors; the remainder are convex. The low Co and Ni contents at the edge of grains in chondrule margins are interpreted to reflect dilution by Fe produced by FeO reduction.

  19. Sex- and age-related variation in metal content of penguin feathers.

    Science.gov (United States)

    Squadrone, Stefania; Abete, Maria Cesarina; Brizio, Paola; Monaco, Gabriella; Colussi, Silvia; Biolatti, Cristina; Modesto, Paola; Acutis, Pier Luigi; Pessani, Daniela; Favaro, Livio

    2016-03-01

    The presence of xenobiotics, such as metals, in ecosystems is concerning due to their durability and they pose a threat to the health and life of organisms. Moreover, mercury can biomagnify in many marine food chains and, therefore, organisms at higher trophic levels can be adversely impacted. Although feathers have been used extensively as a bio-monitoring tool, only a few studies have addressed the effect of both age and sex on metal accumulation. In this study, the concentrations of trace elements were determined in the feathers of all members of a captive colony of African Penguins (Spheniscus demersus) housed in a zoological facility in Italy. Tests were performed by inductively coupled plasma-mass spectrometry to detect aluminum, arsenic, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, selenium, tin, vanadium, and zinc. Mercury was detected by a direct mercury analyzer. Sexing was performed by a molecular approach based on analyzing the chromo-helicase-DNA-binding1 gene, located on the sex chromosomes. Sex- and age-related differences were studied in order to investigate the different patterns of metal bioaccumulation between male and female individuals and between adults and juveniles. Juvenile females had significantly higher arsenic levels than males, while selenium levels increased significantly with age in both sexes. Penguins kept in controlled environments-given that diet and habitat are under strict control-represent a unique opportunity to determine if and how metal bioaccumulation is related to sex and age.

  20. Infant and mother related outcomes from exposure to metals with endocrine disrupting properties during pregnancy

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, A. [Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa (Canada); Kumarathasan, P. [Environmental Health Science and Research Bureau, Health Canada, Ottawa (Canada); Gomes, J., E-mail: jgomes@uottawa.ca [Interdisciplinary School of Health Sciences, University of Ottawa, Ottawa (Canada); McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa (Canada)

    2016-11-01

    Background: Endocrine-related adverse health effects from exposure to heavy metals such as lead, arsenic, cadmium, and mercury are yet to be adequately described. The purpose of this review was to gain insight into maternal exposure to heavy metals, and to identify potential endocrine-related adverse health effects in the mother and the infant. Methods: Relevant databases were searched for original research reports and a total of 46 articles were retained for scrutiny. Required data was extracted from these studies and their methodology was assessed. Results: Impaired fetal growth was observed from exposure to all endocrine disrupting metals, while exposure to lead and arsenic were associated with spontaneous abortion, stillbirth and neonatal deaths. Maternal exposure to arsenic was associated with impaired glucose tolerance in these mothers. Conclusion: Impaired fetal growth, fetal loss, and neonatal deaths were significantly associated with heavy metals exposure during pregnancy; however, hypertension and gestational diabetes require further investigation. - Highlights: • Low and high dose exposure to lead was associated with low birth weight, preterm birth, stillbirths, spontaneous abortions and hypertension. • Exposure to arsenic was associated with fetal loss, stillbirths and spontaneous abortions. • Exposure to cadmium was associated with low birth weight. • Exposure to mercury was associated with spontaneous abortions and neurotoxic effects. • Exposure to copper was associated with low birth weight and spontaneous abortions and exposure to zinc was associated with low birth weight.

  1. Infant and mother related outcomes from exposure to metals with endocrine disrupting properties during pregnancy

    International Nuclear Information System (INIS)

    Rahman, A.; Kumarathasan, P.; Gomes, J.

    2016-01-01

    Background: Endocrine-related adverse health effects from exposure to heavy metals such as lead, arsenic, cadmium, and mercury are yet to be adequately described. The purpose of this review was to gain insight into maternal exposure to heavy metals, and to identify potential endocrine-related adverse health effects in the mother and the infant. Methods: Relevant databases were searched for original research reports and a total of 46 articles were retained for scrutiny. Required data was extracted from these studies and their methodology was assessed. Results: Impaired fetal growth was observed from exposure to all endocrine disrupting metals, while exposure to lead and arsenic were associated with spontaneous abortion, stillbirth and neonatal deaths. Maternal exposure to arsenic was associated with impaired glucose tolerance in these mothers. Conclusion: Impaired fetal growth, fetal loss, and neonatal deaths were significantly associated with heavy metals exposure during pregnancy; however, hypertension and gestational diabetes require further investigation. - Highlights: • Low and high dose exposure to lead was associated with low birth weight, preterm birth, stillbirths, spontaneous abortions and hypertension. • Exposure to arsenic was associated with fetal loss, stillbirths and spontaneous abortions. • Exposure to cadmium was associated with low birth weight. • Exposure to mercury was associated with spontaneous abortions and neurotoxic effects. • Exposure to copper was associated with low birth weight and spontaneous abortions and exposure to zinc was associated with low birth weight.

  2. Donnan membrane speciation of Al, Fe, trace metals and REEs in coastal lowland acid sulfate soil-impacted drainage waters.

    Science.gov (United States)

    Jones, Adele M; Xue, Youjia; Kinsela, Andrew S; Wilcken, Klaus M; Collins, Richard N

    2016-03-15

    Donnan dialysis has been applied to forty filtered drainage waters collected from five coastal lowland acid sulfate soil (CLASS) catchments across north-eastern NSW, Australia. Despite having average pH values70%) as negatively-charged complexes. In contrast, the speciation of the divalent trace metals Co, Mn, Ni and Zn was dominated by positively-charged complexes and was strongly correlated with the alkaline earth metals Ca and Mg. Thermodynamic equilibrium speciation calculations indicated that natural organic matter (NOM) complexes dominated Fe(III) speciation in agreement with that obtained by Donnan dialysis. In the case of Fe(II), however, the free cation was predicted to dominate under thermodynamic equilibrium, whilst our results indicated that Fe(II) was mainly present as neutral or negatively-charged complexes (most likely with sulfate). For all other divalent metals thermodynamic equilibrium speciation calculations agreed well with the Donnan dialysis results. The proportion of Al and REEs predicted to be negatively-charged was also grossly underestimated, relative to the experimental results, highlighting possible inaccuracies in the stability constants developed for these trivalent Me(SO4)2(-) and/or Me-NOM complexes and difficulties in modeling complex environmental samples. These results will help improve metal mobility and toxicity models developed for CLASS-affected environments, and also demonstrate that Australian CLASS environments can discharge REEs at concentrations an order of magnitude greater than previously reported. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. A NEW SCALING RELATION FOR H II REGIONS IN SPIRAL GALAXIES: UNVEILING THE TRUE NATURE OF THE MASS-METALLICITY RELATION

    International Nuclear Information System (INIS)

    Rosales-Ortega, F. F.; Díaz, A. I.; Sánchez, S. F.; Iglesias-Páramo, J.; Vílchez, J. M.; Mast, D.; Bland-Hawthorn, J.; Husemann, B.

    2012-01-01

    We demonstrate the existence of a local mass, metallicity, star formation relation using spatially resolved optical spectroscopy of H II regions in the local universe. One of the projections of this distribution—the local mass-metallicity relation—extends over a wide range in this parameter space: three orders of magnitude in mass and a factor of eight in metallicity. We explain the new relation as the combined effect of the differential distributions of mass and metallicity in the disks of galaxies, and a selective star formation efficiency. We use this local relation to reproduce—with a noticeable agreement—the mass-metallicity relation seen in galaxies, and conclude that the latter is a scale-up integrated effect of a local relation, supporting the inside-out growth and downsizing scenarios of galaxy evolution.

  4. Trace metals in Antarctica related to climate change and increasing human impact.

    Science.gov (United States)

    Bargagli, R

    2000-01-01

    in most samples of atmospheric particulates, snow, ice, soils, and marine sediments from Antarctica can be taken as global background levels. Comparison between the results of trace element surveys in marine waters of the Southern Ocean and in other seas is practically impossible. The upwelling or subduction of water masses, the seasonality in ice cover and in phytoplankton biomass, the low fallout of atmospheric dust, and many other peculiar characteristics of the Southern Ocean make concentrations of trace metals in surface waters quite variable in space and time. The depletion of nutrients in surface waters, which is a regular feature of many marine environments, rarely occurs in the Southern Ocean. Waters in some regions are characterized by very low concentrations of Fe and Mn, whereas in others the content of Cd is relatively high at the beginning of summer and may decrease about one order of magnitude during the phytoplankton bloom. Although in most Antarctic coastal ecosystems the input of metals from geochemical and anthropogenic sources and from long-range transport is negligible, concentrations of Cd in the waters and biota may be higher than in waters and related species of organisms from polluted coastal areas. Like the Southern Ocean, Antarctic lakes have many peculiar characteristics. They are often perennially ice covered and without outlet, and their water, which is gained only from short-term melting of snow and glaciers in summer, is lost mainly by sublimation of surface ice. Several lakes are distinctly stratified: the water under the ice may be cool, rich in oxygen, and among the cleanest and clearest of natural waters, whereas water near the bottom becomes anoxic, tepid, and richer in major and trace elements. Considering the specificity of Antarctic environments, to evaluate the extent and consequences of global changes and increasing human activities in Antarctica itself, research on the biogeochemistry of trace metals and monitoring programs

  5. Cytotoxic mechanism related to dihydrolipoamide dehydrogenase in Leydig cells exposed to heavy metals

    International Nuclear Information System (INIS)

    Ji, Xunmin; Li, Zhiliang; Chen, Hongxia; Li, Junqi; Tian, Huajian; Li, Zengli; Gao, Xuejuan; Xiang, Qi; Su, Zhijian; Huang, Yadong; Zhang, Qihao

    2015-01-01

    Heavy metals are common environmental toxicants with adverse effects on steroid biosynthesis. The importance of mitochondria has been recognized in cytotoxic mechanism of heavy metals on Leydig cells these years. But it is still poorly known. Our previous study reported that dihydrolipoamide dehydrogenase (DLD) located on the mitochondria was significantly decreased in Leydig cells exposed to cadmium, which suggested that DLD might be involved in the cytotoxic effects. Therefore, the altered expression of DLD was validated in rats and R2C cells exposed to cadmium, manganese and lead, and the role of DLD in the steroid synthesis pathway cAMP/PKA-ERK1/2 was investigated in this study. With a low expression of DLD, heavy metals dramatically reduced the levels of steroid hormone by inhibiting the activation of cAMP/PKA, PKC signaling pathway and the steroidogenic enzymes StAR, CYP11A1 and 3β-HSD. After knockdown of DLD in R2C cells, progesterone synthesis was reduced by 40%, and the intracellular concentration of cAMP, protein expression of StAR, 3β-HSD, PKA, and the phosphorylation of ERK1/2 were also decreased. These results highlight that DLD is down-regulation and related to steroid biosynthesis in Leyig cells exposed to heavy metals; cAMP/PKA act as downstream effector molecules of DLD, which activate phosphorylation of ERK1/2 to initiate the steroidogenesis

  6. Bulk band gaps in divalent hexaborides: A soft x-ray emission study

    International Nuclear Information System (INIS)

    Denlinger, Jonathan D.; Gweon, Gey-Hong; Allen, James W.; Bianchi, Andrea D.; Fisk, Zachary

    2001-01-01

    Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band

  7. Ion exchange equilibrium for some uni-univalent and uni-divalent ...

    African Journals Online (AJOL)

    The study on thermodynamics of ion exchange equilibrium for uni-univalent Cl-/I-, Cl-/Br-, and uni-divalent Cl-/SO42-, Cl-/C2O42- reaction systems was carried out using ion exchange resin Duolite A-102 D. The equilibrium constant K was calculated by taking into account the activity coefficient of ions both in solution as well ...

  8. Surface density: a new parameter in the fundamental metallicity relation of star-forming galaxies

    Science.gov (United States)

    Hashimoto, Tetsuya; Goto, Tomotsugu; Momose, Rieko

    2018-04-01

    Star-forming galaxies display a close relation among stellar mass, metallicity, and star formation rate (or molecular-gas mass). This is known as the fundamental metallicity relation (FMR) (or molecular-gas FMR), and it has a profound implication on models of galaxy evolution. However, there still remains a significant residual scatter around the FMR. We show here that a fourth parameter, the surface density of stellar mass, reduces the dispersion around the molecular-gas FMR. In a principal component analysis of 29 physical parameters of 41 338 star-forming galaxies, the surface density of stellar mass is found to be the fourth most important parameter. The new 4D fundamental relation forms a tighter hypersurface that reduces the metallicity dispersion to 50 per cent of that of the molecular-gas FMR. We suggest that future analyses and models of galaxy evolution should consider the FMR in a 4D space that includes surface density. The dilution time-scale of gas inflow and the star-formation efficiency could explain the observational dependence on surface density of stellar mass.

  9. On the determination of representative stress–strain relation of metallic materials using instrumented indentation

    International Nuclear Information System (INIS)

    Fu, Kunkun; Chang, Li; Zheng, Bailin; Tang, Youhong; Wang, Hongjian

    2015-01-01

    Highlights: • A method to convert indentation load–depth curve into representative stress–strain curve is presented. • Representative stress–strain curves of six metals are obtained using finite element analysis. • Different representative strain definitions are compared using finite element method. • Representative stress–strain curve of molybdenum films is obtained by nanoindentation tests. - Abstract: In this study, attempts have been made to estimate the representative stress–strain relation of metallic materials from indentation tests using an iterative method. Finite element analysis was performed to validate the method. The results showed that representative stress–strain relations of metallic materials using the present method were in a good agreement with those from tensile tests. Further, this method was extended to predict representative stress–strain relation of ultra-thin molybdenum films with a thickness of 485 nm using nanoindentation. Yielding strength and strain hardening exponent of the films were therefore obtained, which showed a good agreement with the published data

  10. Novel DOTA-based prochelator for divalent peptide vectorization: synthesis of dimeric bombesin analogues for multimodality tumor imaging and therapy.

    Science.gov (United States)

    Abiraj, Keelara; Jaccard, Hugues; Kretzschmar, Martin; Helm, Lothar; Maecke, Helmut R

    2008-07-28

    Dimeric peptidic vectors, obtained by the divalent grafting of bombesin analogues on a newly synthesized DOTA-based prochelator, showed improved qualities as tumor targeted imaging probes in comparison to their monomeric analogues.

  11. Effect of divalent ions on the optical emission behavior of protein thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bhowal, Ashim Chandra, E-mail: ashimbhowal111@gmail.com; Kundu, Sarathi [Physical Sciences Division, Institute of Advanced Study in Science and Technology, Vigyan Path, Paschim Boragaon, Garchuk, Guwahati, Assam 781035 (India)

    2016-05-06

    Photoluminescence behaviors of proteinthin film, bovine serum albumin (BSA) have been studied in the presence of three divalent ions (Mg{sup 2+}, Ca{sup 2+} and Ba{sup 2+}) at different temperatures using fluorescence spectroscopy. Film thickness and morphology have been studied using atomic force microscopy. Variation of different physicochemical parameters like temperature, solvent polarity, pH, ionic strength, substrate binding etc. can make conformational changes in the protein structure and hence influences the emission behavior.In thin film conformation of BSA, dynamic quenching behavior has beenidentified in the presence of all the three divalent ions at pH≈ 5.5. Depending upon the charge density of the divalent ions interaction with protein molecules modifies and as a result quenching efficiency varies. Also after heat treatment, conformation of the protein molecules changes and as a result the quenching efficiency enhances than that of the unheated films. Studies on such protein-ion interactions and conformational variation may explore various functions of protein when it will adsorb on soft surfaces like membranes, vesicles, etc.

  12. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  13. Heavy metals content in degraded agricultural soils of a mountain region related to soil properties

    Science.gov (United States)

    Navarro-Pedreño, José; Belén Almendro-Candel, María; Gómez, Ignacio; Jordán, Manuel M.; Bech, Jaume; Zorpas, Antonis

    2017-04-01

    Agriculture has been practiced for long time in Mediterranean regions. Intensive agriculture and irrigation have developed mainly in the valleys and coastal areas. In the mountainous areas, dry farming has been practiced for centuries. Soils have been fertilized using mainly organic amendments. Plants extracted nutrients and other elements like heavy metals presented in soils and agricultural practices modified soil properties that could favor the presence of heavy metals. In this work, it has been checked the content of heavy metals in 100 agricultural soils samples of the NorthWest area of the province of Alicante (Spain) which has been long cultivated with cereals and olive trees, and now soils are abandoned and degraded because of the low agricultural yields. European policy has the aim to improve the sustainable agriculture and recover landscapes of mountain regions. So that, it is important to check the state of the soils (Marques et al. 2007). Soils samples (arable layer) were analyzed determining: pH (1:5, w/v, water extract), equivalent calcium carbonate content, organic matter by Walkley-Black method (Nelson and Sommers 1996), micronutrients (Cu, Fe, Mn, Zn) extracted with DTPA (Lindsay and Norvell, 1978) and measured by atomic absorption spectrometry, and total content of metals (Cd, Cr, Ni, Pb) measured in soil samples after microwave acid digestion (Moral et al. 1996), quantifying the content of metals by ICP analysis. The correlation between soil properties and metals. The results indicated that pH and carbonates are the most important properties of these soils correlated with the metals (both micronutrients and heavy metals). The available micronutrients (all of them) are close correlated with the pH and carbonates in soils. Moreover, heavy metals like Pb and Ni are related to available Mn and Zn. Keywords: pH, carbonates, heavy metals, abandoned soils. References: Lindsay,W.L., andW.A. Norvell. 1978. "Development of a DTPA Soil Test for Zinc, Iron

  14. Relating environmental availability to bioavailability: soil-type-dependent metal accumulation in the oligochaete Eisenia andrei.

    Science.gov (United States)

    Peijnenburg, W J; Baerselman, R; de Groot, A C; Jager, T; Posthuma, L; Van Veen, R P

    1999-11-01

    Body residues are often better estimates of the amount of a chemical at the sites of toxic action in an organism than ambient soil concentrations, because bioavailability differences among soils are explicitly taken into account in considerations of body residues. Often, however, insufficient attention is paid to the rate and extent at which tissue concentrations respond to soil concentrations and soil characteristics. In this contribution the impact of soil characteristics on the environmental bioavailability of heavy metals for the oligochaete worm Eisenia andrei is reported. Uptake of As, Cd, Cr, Cu, Ni, Pb, and Zn in 20 Dutch field soils and in OECD artificial soil was quantified as a function of time. Internal metal concentrations varied less than the corresponding external levels. Metal uptake and elimination were both metal- and species-dependent. Worms typically attained steady-state concentrations rapidly for Cr, Cu, Ni, and Zn. Internal concentrations similar to those in the cultivation medium, linearly increasing body concentrations, or steady-state internal concentrations well above those in the cultivation medium were found for As, Cd, and Pb. Multivariate expressions were derived to describe uptake rate constants, steady-state concentrations, and bioaccumulation factors as a function of soil characteristics. Soil acidity is the most important solid-phase characteristic modulating the availability of As, Cd, and Pb. Although additional semimechanistic calculations yielded evidence of pore-water-related uptake of Cd and Pb modulated by competition between H(+) and metal ions at the active sites of the membranes, the findings for Cr, Cu, Ni, and Zn point to additional influences, among which is probably regulation. Copyright 1999 Academic Press.

  15. Nuclear methods applied for studies of contact phenomena in metal-fluid media and between metallic components in relative motion

    International Nuclear Information System (INIS)

    Racolta, P.M.; Popa-Simil, L.; Voiculescu, Dana; Muntele, C. I.

    1997-01-01

    The two main goals of this research project were: establishing of an activation methodology for metallic structures using accelerated beams obtained at our cyclotron and adapting the spectrometric analysis methods of the gamma radiations for corrosion level determinations. The developed methods, including the calibration (relations between the radioactivity level and the thickness of removed layer due to corrosion), were based on the remnant radioactivity measuring method. The experiments were focused on a proper selection of the nuclear reaction to be utilised for measurements, depending on the type of metallic alloys investigated. This study also consisted of optimizing the irradiation (particle, energy and dose) and cooling time so as to obtain a measuring sensitivity of 0.1-1μm for Fe, Ti, V, Cr, Cu, Mo based alloys. A portable two-channel γ-spectrometric installation was adapted to a customer's corrosion testing stand. Corrosion levels of a Romanian-made injection pump working with different types of Diesel oils and Diesel oil + special additives + water mixtures were determined. The nuclear reactions used were 56 Fe (p,n) 56 Co and 56 Fe (d,n) 57 Co. A selected area of the pump's piston was activated up to 30 μm. The testing programme was made for 300 h working times on the test stand; corrosion levels of approx. 0.3 μm were observed. In cooperation with a group from Tribology Laboratory from the Bucharest Technical University, Ti-coated pallets of a water pump were tested in their near real working environment - salty and sandy water. The 48 Ti (p,n) 48 V nuclear reaction was used for labelling a Ti thickness up to 50 μm. In this experiment, the main interest was to determine the minimum detectable corroded thickness by this radiotracer - based method. Our measurements showed that sensitivities of 0.05 - 1 μm can be achieved. In 1996, in cooperation with the National Institute for Thermal Engines, the wear of the piston ring - cylinder jacket friction

  16. The relation between Acid Volatile Sulfides (AVS) and metal accumulation in aquatic invertebrates: Implications of feeding behavior and ecology

    International Nuclear Information System (INIS)

    De Jonge, Maarten; Blust, Ronny; Bervoets, Lieven

    2010-01-01

    The present study evaluates the relationship between Acid Volatile Sulfides (AVS) and metal accumulation in invertebrates with different feeding behavior and ecological preferences. Natural sediments, pore water and surface water, together with benthic and epibenthic invertebrates were sampled at 28 Flemish lowland rivers. Different metals as well as metal binding sediment characteristics including AVS were measured and multiple regression was used to study their relationship with accumulated metals in the invertebrates taxa. Bioaccumulation in the benthic taxa was primarily influenced by total metal concentrations in the sediment. Regarding the epibenthic taxa metal accumulation was mostly explained by the more bioavailable metal fractions in both the sediment and the water. AVS concentrations were generally better correlated with metal accumulation in the epibenthic invertebrates, rather than with the benthic taxa. Our results indicated that the relation between AVS and metal accumulation in aquatic invertebrates is highly dependent on feeding behavior and ecology. - The relation between AVS and metal accumulation in aquatic invertebrates is highly dependent on feeding behavior and ecology.

  17. Probing galaxy growth through metallicity scaling relations over the past 12 Gyr of cosmic history

    Science.gov (United States)

    Sanders, Ryan; MOSDEF team

    2018-01-01

    A primary goal of galaxy evolution studies is to understand the processes governing the growth of the baryonic content of galaxies over cosmic history. Observations of galaxy metallicity scaling relations and their evolution with redshift, in combination with chemical evolution models, provide unique insight into the interplay between star formation, gas accretion, and feedback/outflows. I present measurements of the stellar mass-gas phase metallicity relation and its evolution over the past 12 Gyr from z~0 to z~3.5, utilizing data from the Mosfire Deep Evolution Field survey that uniquely provides rest-frame optical spectra of >1000 uniformly-selected galaxies at z=1.3-3.8. We find evolution towards lower metallicity at fixed stellar mass with increasing redshift that is consistent with current cosmological simulations including chemical evolution, with a large evolution of ~0.3 dex from z~0 to z~2.5 and minor evolution of 2, and discuss the potential of current and next-generation observational facilities to obtain statistical auroral-line samples at high redshifts.

  18. Species- and age-related variation in metal exposure and accumulation of two passerine bird species

    Energy Technology Data Exchange (ETDEWEB)

    Berglund, A.M.M., E-mail: asa.berglund@emg.umu.se [Section of Ecology, 20014 University of Turku (Finland); Koivula, M.J.; Eeva, T. [Section of Ecology, 20014 University of Turku (Finland)

    2011-10-15

    We measured the concentration of several elements (arsenic [As], calcium [Ca], cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], selenium [Se] and zinc [Zn]) in adult and nestling pied flycatchers (Ficedula hypoleuca) and great tits (Parus major) at different distances to a Cu-Ni smelter in 2009. Feces of nestlings generally failed to correspond with internal element concentrations but reflected the pollution exposure, indicating an increased stress by removal of excess metals. The uptake of Cu and Ni were regulated, but As, Cd, Pb and Se accumulated in liver tissue. Pied flycatchers had generally higher element concentrations than great tits. The higher accumulation of As and Pb in pied flycatcher livers was explained by a more efficient absorption, whereas the higher Cd concentration was primarily due to different intake of food items. Age-related differences occurred between the two species, though both Cd and Se accumulated with age. - Highlights: > We measured metal concentrations in feces and livers of two passerine species. > We examined species- and age-related differences in polluted environments. > Feces was evaluated as a useful non-destructive measure of increased stress. > Generally pied flycatchers accumulated higher concentrations than great tits. > Cadmium and selenium accumulated with age in both species. - Accumulation of metals in liver of two insectivorous passerines reflects inter-specific differences in diet, absorption rate and physiological requirements.

  19. Species- and age-related variation in metal exposure and accumulation of two passerine bird species

    International Nuclear Information System (INIS)

    Berglund, A.M.M.; Koivula, M.J.; Eeva, T.

    2011-01-01

    We measured the concentration of several elements (arsenic [As], calcium [Ca], cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], selenium [Se] and zinc [Zn]) in adult and nestling pied flycatchers (Ficedula hypoleuca) and great tits (Parus major) at different distances to a Cu-Ni smelter in 2009. Feces of nestlings generally failed to correspond with internal element concentrations but reflected the pollution exposure, indicating an increased stress by removal of excess metals. The uptake of Cu and Ni were regulated, but As, Cd, Pb and Se accumulated in liver tissue. Pied flycatchers had generally higher element concentrations than great tits. The higher accumulation of As and Pb in pied flycatcher livers was explained by a more efficient absorption, whereas the higher Cd concentration was primarily due to different intake of food items. Age-related differences occurred between the two species, though both Cd and Se accumulated with age. - Highlights: → We measured metal concentrations in feces and livers of two passerine species. → We examined species- and age-related differences in polluted environments. → Feces was evaluated as a useful non-destructive measure of increased stress. → Generally pied flycatchers accumulated higher concentrations than great tits. → Cadmium and selenium accumulated with age in both species. - Accumulation of metals in liver of two insectivorous passerines reflects inter-specific differences in diet, absorption rate and physiological requirements.

  20. The alteration of oxidation and related properties of metals by ion implantation

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1981-01-01

    A review is given of the various ways in which ion implanted additives can affect the thermal oxidation of metals, for example by blocking diffusion paths for ions, by catalytic effects or by altering the plasticity of the oxide. The versatility of the process has already proved useful in the study of oxidation mechanisms. Ways of achieving a long-lasting protection are discussed in relation to the dominant mechanisms of oxidation inhibition. In many practical applications at elevated temperatures oxidation and mechanical stresses co-exist. In steels the process of oxidative wear is important under conditions of poor lubrication and implanted metallic ions have been shown to be effective. In titanium alloys fatigue cracks probably initiate at dislocation sites at which oxidation proceeds most rapidly, and hence the same implanted species can improve both types of behaviour. Successful implantation treatments for fretting fatigue in titanium and a corrosion-erosion problem in steel are described. (orig.)

  1. THE KENNICUTT–SCHMIDT RELATION IN EXTREMELY METAL-POOR DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Filho, M. E.; Almeida, J. Sánchez; Muñoz-Tuñón, C. [Instituto Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain); Amorín, R. [National Institute for Astrophysics, Astronomical Observatory of Rome, Via Frascati 33, I-00040 Monteporzio Catone (Rome) (Italy); Elmegreen, B. G. [IBM, T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Elmegreen, D. M., E-mail: mfilho@astro.up.pt [Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States)

    2016-04-01

    The Kennicutt–Schmidt (KS) relation between the gas mass and star formation rate (SFR) describes the star formation regulation in disk galaxies. It is a function of gas metallicity, but the low-metallicity regime of the KS diagram is poorly sampled. We have analyzed data for a representative set of extremely metal-poor galaxies (XMPs), as well as auxiliary data, and compared these to empirical and theoretical predictions. The majority of the XMPs possess high specific SFRs, similar to high-redshift star-forming galaxies. On the KS plot, the XMP H i data occupy the same region as dwarfs and extend the relation for low surface brightness galaxies. Considering the H i gas alone, a considerable fraction of the XMPs already fall off the KS law. Significant quantities of “dark” H{sub 2} mass (i.e., not traced by CO) would imply that XMPs possess low star formation efficiencies (SFE{sub gas}). Low SFE{sub gas} in XMPs may be the result of the metal-poor nature of the H i gas. Alternatively, the H i reservoir may be largely inert, the star formation being dominated by cosmological accretion. Time lags between gas accretion and star formation may also reduce the apparent SFE{sub gas}, as may galaxy winds, which can expel most of the gas into the intergalactic medium. Hence, on global scales, XMPs could be H i-dominated, high-specific-SFR (≳10{sup −10} yr{sup −1}), low-SFE{sub gas} (≲10{sup −9} yr{sup −1}) systems, in which the total H i mass is likely not a good predictor of the total H{sub 2} mass, nor of the SFR.

  2. Assessment of Trace Metals in Soil, Vegetation and Rodents in Relation to Metal Mining Activities in an Arid Environment.

    Science.gov (United States)

    Méndez-Rodríguez, Lia C; Alvarez-Castañeda, Sergio Ticul

    2016-07-01

    Areas where abandoned metal-extraction mines are located contain large quantities of mineral wastes derived from environmentally unsafe mining practices. These wastes contain many pollutants, such as heavy metals, which could be released to the environment through weathering and leaching, hence becoming an important source of environmental metal pollution. This study evaluates differences in the levels of lead, iron, nickel, manganese, copper and cadmium in rodents sharing the same type of diet under different microhabitat use in arid areas with past mining activities. Samples of soil, roots, branches and seeds of Palo Adán (Fouquieria diguetii) and specimens of two rodent species (Chaetodipus arenarius and C. spinatus) were collected in areas with impact from past metal mining activities as well as from areas with no mining impact. Both rodent species mirrored nickel and iron levels in soil and seeds, as well as lead levels in soil; however, C. arenarius accumulated higher levels of manganese, copper and cadmium.

  3. The mass-metallicity relations for gas and stars in star-forming galaxies: strong outflow versus variable IMF

    Science.gov (United States)

    Lian, Jianhui; Thomas, Daniel; Maraston, Claudia; Goddard, Daniel; Comparat, Johan; Gonzalez-Perez, Violeta; Ventura, Paolo

    2018-02-01

    We investigate the mass-metallicity relations for the gaseous (MZRgas) and stellar components (MZRstar) of local star-forming galaxies based on a representative sample from Sloan Digital Sky Survey Data Release 12. The mass-weighted average stellar metallicities are systematically lower than the gas metallicities. This difference in metallicity increases towards galaxies with lower masses and reaches 0.4-0.8 dex at 109 M⊙ (depending on the gas metallicity calibration). As a result, the MZRstar is much steeper than the MZRgas. The much lower metallicities in stars compared to the gas in low-mass galaxies imply dramatic metallicity evolution with suppressed metal enrichment at early times. The aim of this paper is to explain the observed large difference in gas and stellar metallicity and to infer the origin of the mass-metallicity relations. To this end we develop a galactic chemical evolution model accounting for star formation, gas inflow and outflow. By combining the observed mass-metallicity relation for both gas and stellar components to constrain the models, we find that only two scenarios are able to reproduce the observations. Either strong metal outflow or a steep initial mass function (IMF) slope at early epochs of galaxy evolution is needed. Based on these two scenarios, for the first time we successfully reproduce the observed MZRgas and MZRstar simultaneously, together with other independent observational constraints in the local Universe. Our model also naturally reproduces the flattening of the MZRgas at the high-mass end leaving the MZRstar intact, as seen in observational data.

  4. INSIGHTS ON THE STELLAR MASS-METALLICITY RELATION FROM THE CALIFA SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    González Delgado, R. M.; García-Benito, R.; Pérez, E.; Cortijo-Ferrero, C.; López Fernández, R.; Sánchez, S. F. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Cid Fernandes, R.; De Amorim, A. L.; Lacerda, E. A. D.; Vale Asari, N. [Departamento de Física, Universidade Federal de Santa Catarina, P.O. Box 476, 88040-900 Florianópolis, SC (Brazil); Alves, J. [University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Bland-Hawthorn, J. [Sydney Institute for Astronomy, The University of Sydney, NSW 2006 (Australia); Galbany, L. [Millennium Institute of Astrophysics and Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile); Gallazzi, A. [INAF—Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, I-50125 Firenze (Italy); Husemann, B. [European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching b. München (Germany); Bekeraite, S. [Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany); Jungwiert, B. [Astronomical Institute of the Academy of Sciences of the Czech Republic, v.v.i., Bocni II 1401, 14131 Prague (Czech Republic); López-Sánchez, A. R. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); De Lorenzo-Cáceres, A. [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, KY16 9SS (United Kingdom); Marino, R. A. [CEI Campus Moncloa, UCM-UPM, Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Collaboration: CALIFA collaboration920; and others

    2014-08-10

    We use spatially and temporally resolved maps of stellar population properties of 300 galaxies from the CALIFA integral field survey to investigate how the stellar metallicity (Z {sub *}) relates to the total stellar mass (M {sub *}) and the local mass surface density (μ{sub *}) in both spheroidal- and disk-dominated galaxies. The galaxies are shown to follow a clear stellar mass-metallicity relation (MZR) over the whole 10{sup 9}-10{sup 12} M {sub ☉} range. This relation is steeper than the one derived from nebular abundances, which is similar to the flatter stellar MZR derived when we consider only young stars. We also find a strong relation between the local values of μ{sub *} and Z {sub *} (the μZR), betraying the influence of local factors in determining Z {sub *}. This shows that both local (μ{sub *}-driven) and global (M {sub *}-driven) processes are important in determining metallicity in galaxies. We find that the overall balance between local and global effects varies with the location within a galaxy. In disks, μ{sub *} regulates Z {sub *}, producing a strong μZR whose amplitude is modulated by M {sub *}. In spheroids it is M {sub *} that dominates the physics of star formation and chemical enrichment, with μ{sub *} playing a minor, secondary role. These findings agree with our previous analysis of the star formation histories of CALIFA galaxies, which showed that mean stellar ages are mainly governed by surface density in galaxy disks and by total mass in spheroids.

  5. Donnan membrane speciation of Al, Fe, trace metals and REEs in coastal lowland acid sulfate soil-impacted drainage waters

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Adele M.; Xue, Youjia [School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Kinsela, Andrew S. [School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Institute for Environmental Research (IER), Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234 (Australia); Wilcken, Klaus M. [Institute for Environmental Research (IER), Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234 (Australia); Collins, Richard N., E-mail: richard.collins@unsw.edu.au [School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)

    2016-03-15

    Donnan dialysis has been applied to forty filtered drainage waters collected from five coastal lowland acid sulfate soil (CLASS) catchments across north-eastern NSW, Australia. Despite having average pH values < 3.9, 78 and 58% of Al and total Fe, respectively, were present as neutral or negatively-charged species. Complementary isotope dilution experiments with {sup 55}Fe and {sup 26}Al demonstrated that only soluble (i.e. no colloidal) species were present. Trivalent rare earth elements (REEs) were also mainly present (> 70%) as negatively-charged complexes. In contrast, the speciation of the divalent trace metals Co, Mn, Ni and Zn was dominated by positively-charged complexes and was strongly correlated with the alkaline earth metals Ca and Mg. Thermodynamic equilibrium speciation calculations indicated that natural organic matter (NOM) complexes dominated Fe(III) speciation in agreement with that obtained by Donnan dialysis. In the case of Fe(II), however, the free cation was predicted to dominate under thermodynamic equilibrium, whilst our results indicated that Fe(II) was mainly present as neutral or negatively-charged complexes (most likely with sulfate). For all other divalent metals thermodynamic equilibrium speciation calculations agreed well with the Donnan dialysis results. The proportion of Al and REEs predicted to be negatively-charged was also grossly underestimated, relative to the experimental results, highlighting possible inaccuracies in the stability constants developed for these trivalent Me(SO{sub 4}){sub 2}{sup −} and/or Me–NOM complexes and difficulties in modeling complex environmental samples. These results will help improve metal mobility and toxicity models developed for CLASS-affected environments, and also demonstrate that Australian CLASS environments can discharge REEs at concentrations an order of magnitude greater than previously reported. - Highlights: • CLASS discharge large amounts of metals and their speciation is poorly

  6. Fate of airborne metal pollution in soils as related to agricultural management. 1. Zn and Pb distributions in soil profiles

    NARCIS (Netherlands)

    Fernandez, C.; Labanowski, J.; Cambier, P.; Jongmans, A.G.; Oort, van F.

    2007-01-01

    The fate of airborne metal pollutants in soils is still relatively unknown. We studied the incorporation of such airborne metal pollution in two soils under long-term permanent pasture (PP) and conventional arable land (CA). Both soils were located at an almost equal distance from a former zinc

  7. Treatment of cuff-related tracheal stenosis with a fully covered retrievable expandable metallic stent

    International Nuclear Information System (INIS)

    Chen, G.; Wang, Z.; Liang, X.; Wang, Y.; Wang, Y.; Wang, Z.; Xian, J.

    2013-01-01

    Aim: To investigate the clinical effectiveness, complications, and optimal duration of use of covered retrievable expandable metallic stents in the management of cuff-related tracheal stenosis. Materials and methods: Twenty-one patients with cuff-related tracheal stenosis, Meyer–Cotton grade II (29%) and III (71%), who underwent fluoroscopically guided placement of covered retrievable expandable metallic stents were studied. Sixty-four-section computed tomography (CT) and bronchovideoscopy were performed prior to stent insertion, 1 month after stent insertion, in the case of stent-related complications, and after stent removal. Clinical manifestations, Hugh–Jones classification, and forced expiratory volume in 1 s (FEV1) were used to evaluate respiratory function before and after stent insertion and removal. The diameter of the stricture and FEV1 changes before insertion and after removal were analysed using the paired samples t-test. A p-value of ≤0.05 was considered statistically significant. Results: Twenty-one patients had 27 covered retrievable expandable metallic stents placed. Stents were electively removed from 20 patients. The median duration of stent placement was 5 months (range 4–12 months). One stent was not removed due to mucopolysaccharidosis type II (MPS II or Hunter syndrome) with tracheomalacia. After stent removal, airway dimensions increased and airway occlusion was symptomatically relieved in all patients. CT and bronchovideoscopy showed patent lumens with increased dimensions. Stent-related complications occurred in 19 (91%) patients, including granulation tissue formation (n = 18, 86%), stent migration and stent expectoration (n = 2, 10%), mucus plugging (n = 1, 5%), and halitosis (n = 6, 29%). Some patients experienced multiple complications, which were all managed effectively while the stent was still in place. There was a statistically significant difference in the diameter of the stricture and FEV1 between the time of stent

  8. Treatment of cuff-related tracheal stenosis with a fully covered retrievable expandable metallic stent.

    Science.gov (United States)

    Chen, G; Wang, Z; Liang, X; Wang, Y; Wang, Y; Wang, Z; Xian, J

    2013-04-01

    To investigate the clinical effectiveness, complications, and optimal duration of use of covered retrievable expandable metallic stents in the management of cuff-related tracheal stenosis. Twenty-one patients with cuff-related tracheal stenosis, Meyer-Cotton grade II (29%) and III (71%), who underwent fluoroscopically guided placement of covered retrievable expandable metallic stents were studied. Sixty-four-section computed tomography (CT) and bronchovideoscopy were performed prior to stent insertion, 1 month after stent insertion, in the case of stent-related complications, and after stent removal. Clinical manifestations, Hugh-Jones classification, and forced expiratory volume in 1 s (FEV1) were used to evaluate respiratory function before and after stent insertion and removal. The diameter of the stricture and FEV1 changes before insertion and after removal were analysed using the paired samples t-test. A p-value of ≤0.05 was considered statistically significant. Twenty-one patients had 27 covered retrievable expandable metallic stents placed. Stents were electively removed from 20 patients. The median duration of stent placement was 5 months (range 4-12 months). One stent was not removed due to mucopolysaccharidosis type II (MPS II or Hunter syndrome) with tracheomalacia. After stent removal, airway dimensions increased and airway occlusion was symptomatically relieved in all patients. CT and bronchovideoscopy showed patent lumens with increased dimensions. Stent-related complications occurred in 19 (91%) patients, including granulation tissue formation (n = 18, 86%), stent migration and stent expectoration (n = 2, 10%), mucus plugging (n = 1, 5%), and halitosis (n = 6, 29%). Some patients experienced multiple complications, which were all managed effectively while the stent was still in place. There was a statistically significant difference in the diameter of the stricture and FEV1 between the time of stent insertion and removal. An improvement in

  9. Biased resistor network model for electromigration failure and related phenomena in metallic lines

    Science.gov (United States)

    Pennetta, C.; Alfinito, E.; Reggiani, L.; Fantini, F.; Demunari, I.; Scorzoni, A.

    2004-11-01

    Electromigration phenomena in metallic lines are studied by using a biased resistor network model. The void formation induced by the electron wind is simulated by a stochastic process of resistor breaking, while the growth of mechanical stress inside the line is described by an antagonist process of recovery of the broken resistors. The model accounts for the existence of temperature gradients due to current crowding and Joule heating. Alloying effects are also accounted for. Monte Carlo simulations allow the study within a unified theoretical framework of a variety of relevant features related to the electromigration. The predictions of the model are in excellent agreement with the experiments and in particular with the degradation towards electrical breakdown of stressed Al-Cu thin metallic lines. Detailed investigations refer to the damage pattern, the distribution of the times to failure (TTFs), the generalized Black’s law, the time evolution of the resistance, including the early-stage change due to alloying effects and the electromigration saturation appearing at low current densities or for short line lengths. The dependence of the TTFs on the length and width of the metallic line is also well reproduced. Finally, the model successfully describes the resistance noise properties under steady state conditions.

  10. Environmental hazards related to Miscanthus x giganteus cultivation on heavy metal contaminated soil

    Directory of Open Access Journals (Sweden)

    Pogrzeba M.

    2013-04-01

    Full Text Available According to recent estimates reaching the target of a 20% share of renewable energy sources (RES in the final energy balance in Poland by 2020 will result in the demand for more than 8 million tons of biomass, which, in turn, will entail the necessity of creating large-scale energy crop plantations. According to EU assumptions the most effective way to produce biomass for energy purposes is cultivation of energy crops in agricultural areas. It is particularly vital for Poland, because these areas constitute a relatively large part of the country (59%, 76% of them being used as farmlands. In Silesia, the most industrialized region of the country, 5-10% of agricultural soils are contaminated with cadmium, lead and zinc. The main objective of the presented study was to estimate the accumulation of heavy metals in the tissues of Miscanthus x giganteus grown on contaminated soils and calculate concentrations of Pb, Cd and Zn in crops. It was shown that the large intake of heavy metals by that species could cause high emissions of pollutants into the atmosphere during its improper combustion. As a side effect, winter harvesting led to the loss of even 30% of biomass. Plant residues (leaves can be the source of pollution after decomposing and releasing metals back into the soil. Moreover, miscanthus leaves can be transferred by wind to the surrounding areas. It is very likely that ash coming from the combustion of contaminated biomass cannot be used as a fertilizer.

  11. Data-driven modeling of background and mine-related acidity and metals in river basins

    International Nuclear Information System (INIS)

    Friedel, Michael J.

    2014-01-01

    A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-alteration assemblages and mining activity at 104 independent sites. The SOM correctly predicts (>98%) the predominant type of basin hydrothermal alteration and presence (or absence) of mining activity. Second, application of the Davies–Bouldin criteria to k-means clustering of SOM neurons identified ten unique environmental groups. Median statistics of these groups define a nonlinear water-quality response along the spatiotemporal hydrothermal alteration-mining gradient. These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals, and it provides a basis for future research and empirical model development. The trained self-organizing map is used to determine upstream hydrothermal alteration (AS – acid sulfate; PROP – propylitic, PROP-V – propylitic veins, QSP – quartz-sericite-pyrite, WSP – weak-sericite-pyrite; Mining activity: MINES) from water-quality measurements in the Animas river basin, Colorado, USA. The white hexagons are sized proportional to the number of water-quality samples associated with that SOM neuron. Highlights: • We model surface-water quality response using a self-organizing map and multivariate statistics. • Applying Davies–Bouldin criteria to k-means clusters defines ten environmental response groups. • The approach differentiates between background and mine-related acidity and metals. -- These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals

  12. Leukemia-related mortality in towns lying in the vicinity of metal production and processing installations.

    Science.gov (United States)

    García-Pérez, Javier; López-Cima, María Felicitas; Boldo, Elena; Fernández-Navarro, Pablo; Aragonés, Nuria; Pollán, Marina; Pérez-Gómez, Beatriz; López-Abente, Gonzalo

    2010-10-01

    Releases to the environment of toxic substances stemming from industrial metal production and processing installations can pose a health problem to populations in their vicinity. To investigate whether there might be excess leukemia-related mortality in populations residing in towns in the vicinity of Spanish metal industries included in the European Pollutant Emission Register. Ecologic study designed to examine mortality due to leukemia at a municipal level, during the period 1994-2003. Population exposure to pollution was estimated on the basis of distance from town of residence to pollution source. Using Poisson regression models, we analyzed: risk of dying from leukemia in a 5-kilometer zone around installations which had become operational prior to 1990; effect of pollution discharge route and type of industrial activity; and risk gradient within a 50-kilometer radius of such installations. Excess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations (1.07, 1.02-1.13 in men; 1.05, 1.00-1.11 in women), with this being more elevated in the case of installations that released pollution to air versus water. On stratifying by type of industrial activity, statistically significant associations were also observed among women residing in the vicinity of galvanizing installations (1.58, 1.09-2.29) and surface-treatment installations using an electrolytic or chemical process (1.34, 1.10-1.62), which released pollution to air. There was an effect whereby risk increased with proximity to certain installations. The results suggest an association between risk of dying due to leukemia and proximity to Spanish metal industries. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. FURTHER DEFINITION OF THE MASS-METALLICITY RELATION IN GLOBULAR CLUSTER SYSTEMS AROUND BRIGHTEST CLUSTER GALAXIES

    International Nuclear Information System (INIS)

    Cockcroft, Robert; Harris, William E.; Wehner, Elizabeth M. H.; Whitmore, Bradley C.; Rothberg, Barry

    2009-01-01

    We combine the globular cluster (GC) data for 15 brightest cluster galaxies and use this material to trace the mass-metallicity relations (MMRs) in their globular cluster systems (GCSs). This work extends previous studies which correlate the properties of the MMR with those of the host galaxy. Our combined data sets show a mean trend for the metal-poor subpopulation that corresponds to a scaling of heavy-element abundance with cluster mass Z ∼ M 0.30±0.05 . No trend is seen for the metal-rich subpopulation which has a scaling relation that is consistent with zero. We also find that the scaling exponent is independent of the GCS specific frequency and host galaxy luminosity, except perhaps for dwarf galaxies. We present new photometry in (g',i') obtained with Gemini/GMOS for the GC populations around the southern giant ellipticals NGC 5193 and IC 4329. Both galaxies have rich cluster populations which show up as normal, bimodal sequences in the color-magnitude diagram. We test the observed MMRs and argue that they are statistically real, and not an artifact caused by the method we used. We also argue against asymmetric contamination causing the observed MMR as our mean results are no different from other contamination-free studies. Finally, we compare our method to the standard bimodal fitting method (KMM or RMIX) and find our results are consistent. Interpretation of these results is consistent with recent models for GC formation in which the MMR is determined by GC self-enrichment during their brief formation period.

  14. Enhanced desorption of cesium from collapsed interlayer regions in vermiculite by hydrothermal treatment with divalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Xiangbiao, E-mail: yin.x.aa@m.titech.ac.jp [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Wang, Xinpeng [College of Resources and Metallurgy, Guangxi University, 100 Daxue East Road, Nanning 530004 (China); Wu, Hao; Ohnuki, Toshihiko; Takeshita, Kenji [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2017-03-15

    Highlights: • Desorption of Cs{sup +} fixed in collapsed interlayer region of vermiculite was studied. • Monovalent cations readily induced interlayer collapse inhibiting Cs{sup +} desorption. • Larger hydrous ionic radii of divalent cations greatly prevented Cs{sup +} desorption. • Effect of divalent cation on Cs{sup +} desorption changes depending on thermal treatment. • ∼100% removal of saturated Cs{sup +} was achieved by hydrothermal treatment at 250 °C. - Abstract: Adsorption of cesium (Cs) on phyllosilicates has been intensively investigated because natural soils have strong ability of immobilizing Cs within clay minerals resulting in difficulty of decontamination. The objectives of present study are to clarify how Cs fixation on vermiculite is influenced by structure change caused by Cs sorption at different loading levels and how Cs desorption is affected by various replacing cations induced at different treating temperature. As a result, more than 80% of Cs was readily desorbed from vermiculite with loading amount of 2% saturated Cs (5.49 × 10{sup −3} mmol g{sup −1}) after four cycles of treatment of 0.01 M Mg{sup 2+}/Ca{sup 2+} at room temperature, but less than 20% of Cs was desorbed from saturated vermiculite. These distinct desorption patterns were attributed to inhibition of Cs desorption by interlayer collapse of vermiculite, especially at high Cs loadings. In contrast, elevated temperature significantly facilitated divalent cations to efficiently desorb Cs from collapsed regions. After five cycles of treatment at 250 °C with 0.01 M Mg{sup 2+}, ∼100% removal of saturated Cs was achieved. X-ray diffraction analysis results suggested that Cs desorption was completed through enhanced diffusion of Mg{sup 2+} cations into collapsed interlayer space under hydrothermal condition resulting in subsequent interlayer decollapse and readily release of Cs{sup +}.

  15. Binding of Divalent Cations to Polygalacturonate: A Mechanism Driven by the Hydration Water.

    Science.gov (United States)

    Huynh, Uyen T D; Lerbret, Adrien; Neiers, Fabrice; Chambin, Odile; Assifaoui, Ali

    2016-02-11

    We have investigated the interactions between polygalacturonate (polyGal) and four divalent cations (M(2+) = Ba(2+), Ca(2+), Mg(2+), Zn(2+)) that differ in size and affinity for water. Our results evidence that M(2+)-polyGal interactions are intimately linked to the affinity of M(2+) for water. Mg(2+) interacts so strongly with water that it remains weakly bound to polyGal (polycondensation) by sharing water molecules from its first coordination shell with the carboxylate groups of polyGal. In contrast, the other cations form transient ionic pairs with polyGal by releasing preferentially one water molecule (for Zn(2+)) or two (for Ca(2+) and Ba(2+)), which corresponds to monodentate and bidentate binding modes with carboxylates, respectively. The mechanism for the binding of these three divalent cations to polyGal can be described by two steps: (i) monocomplexation and formation of point-like cross-links between polyGal chains (at low M(2+)/Gal molar ratios, R) and (ii) dimerization (at higher R). The threshold molar ratio, R*, between these two steps depends on the nature of divalent cations and is lower for calcium ions (R* 0.3). This difference may be explained by the intermediate affinity of Ca(2+) for water with respect to those of Zn(2+) and Ba(2+), which may induce the formation of cross-links of intermediate flexibility. By comparison, the lower and higher flexibilities of the cross-links formed by Zn(2+) and Ba(2+), respectively, may shift the formation of dimers to higher molar ratios (R*).

  16. Divalent Cations Regulate the Ion Conductance Properties of Diverse Classes of Aquaporins

    Directory of Open Access Journals (Sweden)

    Mohamad Kourghi

    2017-11-01

    Full Text Available Aquaporins (AQPs are known to facilitate water and solute fluxes across barrier membranes. An increasing number of AQPs are being found to serve as ion channels. Ion and water permeability of selected plant and animal AQPs (plant Arabidopsis thaliana AtPIP2;1, AtPIP2;2, AtPIP2;7, human Homo sapiens HsAQP1, rat Rattus norvegicus RnAQP4, RnAQP5, and fly Drosophila melanogaster DmBIB were expressed in Xenopus oocytes and examined in chelator-buffered salines to evaluate the effects of divalent cations (Ca2+, Mg2+, Ba2+ and Cd2+ on ionic conductances. AtPIP2;1, AtPIP2;2, HsAQP1 and DmBIB expressing oocytes had ionic conductances, and showed differential sensitivity to block by external Ca2+. The order of potency of inhibition by Ca2+ was AtPIP2;2 > AtPIP2;1 > DmBIB > HsAQP1. Blockage of the AQP cation channels by Ba2+ and Cd2+ caused voltage-sensitive outward rectification. The channels with the highest sensitivity to Ca2+ (AtPIP2;1 and AtPIP2;2 showed a distinctive relief of the Ca2+ block by co-application of excess Ba2+, suggesting that divalent ions act at the same site. Recognizing the regulatory role of divalent cations may enable the discovery of other classes of AQP ion channels, and facilitate the development of tools for modulating AQP ion channels. Modulators of AQPs have potential value for diverse applications including improving salinity tolerance in plants, controlling vector-borne diseases, and intervening in serious clinical conditions involving AQPs, such as cancer metastasis, cardiovascular or renal dysfunction.

  17. Multiaxial Cycle Deformation and Low-Cycle Fatigue Behavior of Mild Carbon Steel and Related Welded-Metal Specimen

    Directory of Open Access Journals (Sweden)

    Weilian Qu

    2017-01-01

    Full Text Available The low-cycle fatigue experiments of mild carbon Q235B steel and its related welded-metal specimens are performed under uniaxial, in-phase, and 90° out-of-phase loading conditions. Significant additional cyclic hardening for 90° out-of-phase loading conditions is observed for both base metal and its related weldment. Besides, welding process produces extra additional hardening under the same loading conditions compared with the base metal. Multiaxial low-cycle fatigue strength under 90° out-of-phase loading conditions is significantly reduced for both base-metal and welded-metal specimens. The weldment has lower fatigue life than the base metal under the given loading conditions, and the fatigue life reduction of weldment increases with the increasing strain amplitude. The KBM, FS, and MKBM critical plane parameters are evaluated for the fatigue data obtained. The FS and MKBM parameters are found to show better correlation with fatigue lives for both base-metal and welded-metal specimens.

  18. Traffic Related Aerosol Exposure And Their Risk Assessment Of Associated Metals In Delhi, India

    Directory of Open Access Journals (Sweden)

    Rajesh Kushwaha

    2013-12-01

    Full Text Available A pilot study was carried out in New Delhi, India, to assess the level of traffic related aerosol exposure, individually and associated metals. These investigations also try to formulate their risk assessment using different modes of transport on a typical journey to work route and compared Bus, Auto-rickshaws and Bike (Two Wheelers during the journey. The inhalable particulate matter monitored in winter period and also evaluated the potential health risk due to inhalation in the study. The exposure of Particulate matter was observed maximum in the Bike (502 ± 176.38 μgm-3 and minimum in the Auto-rickshaw (208.15 ± 61.38 μgm-3. In case of human exposure to metals (viz. Cu, Cd, Mn, Pb, Ni, Co, Cr, Fe, Zn, it was mostly exposed by Fe, Zn and Co and least exposed by Cd, Cr and Pb. Human health risk was estimated based on exposure and dosage response. The assessment of particulate-bound elements was calculated by assuming exposure of 6 h. The findings indicated that the exposure to particulate bound elements have relatively more adverse health effects. International Journal of Environment, Volume-2, Issue-1, Sep-Nov 2013, Pages 26-36 DOI: http://dx.doi.org/10.3126/ije.v2i1.9205

  19. Composition dependence of glow peak temperature in KCl1-xBrx doped with divalent cations

    International Nuclear Information System (INIS)

    Perez-Salas, R; Aceves, R; RodrIguez-Mijangos, R; Riveros, H G; Duarte, C

    2004-01-01

    Thermoluminescence measurements of β-irradiated Eu 2+ - and Ca 2+ - doped KCl 1-x KBr x solid solutions excited at room temperature have been carried out to identify the effect of composition on the glow peaks. A typical glow peak has been distinguished for each composition. A linear dependence of its temperature on the composition x has been found. These results indicate that for divalent impurity-doped alkali halide solid solutions these glow peak temperatures are mostly dependent on the lattice constant of the host than on the size of the anion or impurity cation

  20. Nuclear Magnetic Resonance and Elastic Wave Velocity of Chalk Saturated with Brines Containing Divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    divided into groups of three and each group was saturated either with deionized water, calcite equilibrated water, or sodium chloride, magnesium chloride and calcium chloride solutions of the same ionic strength. Saturation with solutions that contain divalent ions caused major shifts in the distribution...... of the relaxation time. Core samples saturated with calcium chloride solution relaxed slower and those saturated with magnesium chloride solution relaxed faster than the rest of the samples. Along with the changes in relaxation the samples experienced smaller velocities of elastic waves when saturated with MgCl2...

  1. The mass-metallicity and fundamental metallicity relations at z > 2 using very large telescope and Subaru near-infrared spectroscopy of zCOSMOS galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Maier, C.; Ziegler, B. L. [Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna (Austria); Lilly, S. J.; Peng, Y. [Institute of Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Contini, T. [Institut de Recherche en Astrophysique et Planétologie, CNRS, 14 avenue Édouard Belin, F-31400 Toulouse (France); Pérez Montero, E. [Instituto de Astrofísica de Andalucia, CSIC, Apartado de Correos 3004, E-18080 Granada (Spain); Balestra, I., E-mail: christian.maier@univie.ac.at [Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstrasse, D-85741 Garching b. München (Germany)

    2014-09-01

    In the local universe, there is good evidence that, at a given stellar mass M, the gas-phase metallicity Z is anti-correlated with the star formation rate (SFR) of the galaxies. It has also been claimed that the resulting Z(M, SFR) relation is invariant with redshift—the so-called 'fundamental metallicity relation' (FMR). Given a number of difficulties in determining metallicities, especially at higher redshifts, the form of the Z(M, SFR) relation and whether it is really independent of redshift is still very controversial. To explore this issue at z > 2, we used VLT-SINFONI and Subaru-MOIRCS near-infrared spectroscopy of 20 zCOSMOS-deep galaxies at 2.1 < z < 2.5 to measure the strengths of up to five emission lines: [O II] λ3727, Hβ, [O III] λ5007, Hα, and [N II] λ6584. This near-infrared spectroscopy enables us to derive O/H metallicities, and also SFRs from extinction corrected Hα measurements. We find that the mass-metallicity relation (MZR) of these star-forming galaxies at z ≈ 2.3 is lower than the local Sloan Digital Sky Survey (SDSS) MZR by a factor of three to five, a larger change than found by Erb et al. using [N II]/Hα-based metallicities from stacked spectra. We discuss how the different selections of the samples and metallicity calibrations used may be responsible for this discrepancy. The galaxies show direct evidence that the SFR is still a second parameter in the MZR at these redshifts. However, determining whether the Z(M, SFR) relation is invariant with epoch depends on the choice of extrapolation used from local samples, because z > 2 galaxies of a given mass have much higher SFRs than the local SDSS galaxies. We find that the zCOSMOS galaxies are consistent with a non-evolving FMR if we use the physically motivated formulation of the Z(M, SFR) relation from Lilly et al., but not if we use the empirical formulation of Mannucci et al.

  2. The effects of pH and concentration on heavy metal speciation and mobility, and its relation to heavy metal hyperaccumulation and distribution in selected native Australian flora

    International Nuclear Information System (INIS)

    Menon, D.D.; McPhail, D.C.; Hallam, N.

    2000-01-01

    Full text: The purpose of this research is to establish a clearer understanding of the relations that exist between heavy metal activity, speciation, bioavailability and their uptake and spatial distribution into plants. A combination of experimental modeling and pot trials using toxic heavy metals (cadmium, lead, mercury, copper, chromium and zinc) will be carried out. In the experiments, selected native Australian flora (Eucalyptus, Acacia, Atriplex) adapted to adverse environmental conditions will be used. Varying external factors such as pH, and metal concentration altered the composition of heavy metal speciation in the soil solution. Mathematical and geochemical (PHREEQC) models were used to vary these factors and emulate the conditions under which experimentation will be taking place. These variations help determine the possible heavy metal speciation that would occur in both soil and hydroponic based experiments under given conditions. The rhizosphere, soil solution and the plant material will be analysed by Inductively Coupled Plasma Mass Spectroscopy (ICPMS). Proton Ion X-ray Emission (PIXE) and Secondary Ion Mass spectrometry will help ascertain the distribution, concentration of heavy metal taken up into plant tissues. Information derived from these data will be used to determine and understand how varying such environmental conditions and hence heavy metal speciation affect their bioavailability in the medium, and how their acceptance, accumulation and storage within the selected flora. Preliminary experimentation showed that, for lead and cadmium, the variation in soil solution pH affected the quantity of heavy metal accumulated into selected native Australian flora. ICP-MS analysis of plants subjected to a known soil solution spiked with 200 μmol of lead and cadmium showed that the quantities of lead and cadmium accumulated into plant sections (roots, stems and leaves) varied in the selected woody species. A. heteroclita, A. saligna, and A

  3. Hemodialysis shunts-related subclavian vein stenosis : treatment with self-expandable metallic stent

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Gyee; Lee, Young Chul; Shin, Sang Soo; Kim, Yun Hyeon; Kim, Jae Kyu; Kang, Heoung Keun; Jeong, Sang Young; Choi, Su Jin Na [Chonnam Univ. College of Medicine, Kwangju (Korea, Republic of)

    1999-04-01

    To evaluate the usefulness of placement of self-expandable stents in hemodialytic shunt-related subclavian vein stenosis. Self-expandable metallic stent was placed in nine patients with hemodialytic shunt-related subclavian vein stenosis. In seven cases, angioplasty was attempted before stent placement; in five, stents were placed immediately after failed angioplasty; and in two, due to restenosis after angioplasty. Procedures involved a 10mm diameter, 7-10cm length Wallstent in eight cases, and a 10mm diameter, 8cm length Hanaro stent in one. In all cases, clinical follow-up, which included physical examination and the measurement of venous resistance pressure during hemodialysis, was performed. The follow-up period was between 5 months and 1 year 7 months. Repeated intervention was performed if restenosis was detected. The stenotic sites were in eight cases the site of a previous subclavian venous line, and in one, the site of anatomic narrowing at the thoracic inlet of the subclavian vein. The technical success rate was 100%;a resulting complication was stent migration into the right atrium in one case in which a Hanaro stent had been used; this was removed by snaring. During follow-up of the eight patients in whon stent placement was successful, restenosis developed in three cases. This occurred during the 7th, 8th, and 15th month, respectively. Two such cases were treated by balloon dilatation. In hemodialytic shunt-related subclavian vein stenosis, treatment involving the use of a self-expandable metallic stent is useful, especially for treating a lesion which has not responded to angioplasty with a high patency rate.

  4. Hemodialysis shunts-related subclavian vein stenosis : treatment with self-expandable metallic stent

    International Nuclear Information System (INIS)

    Kim, Sang Gyee; Lee, Young Chul; Shin, Sang Soo; Kim, Yun Hyeon; Kim, Jae Kyu; Kang, Heoung Keun; Jeong, Sang Young; Choi, Su Jin Na

    1999-01-01

    To evaluate the usefulness of placement of self-expandable stents in hemodialytic shunt-related subclavian vein stenosis. Self-expandable metallic stent was placed in nine patients with hemodialytic shunt-related subclavian vein stenosis. In seven cases, angioplasty was attempted before stent placement; in five, stents were placed immediately after failed angioplasty; and in two, due to restenosis after angioplasty. Procedures involved a 10mm diameter, 7-10cm length Wallstent in eight cases, and a 10mm diameter, 8cm length Hanaro stent in one. In all cases, clinical follow-up, which included physical examination and the measurement of venous resistance pressure during hemodialysis, was performed. The follow-up period was between 5 months and 1 year 7 months. Repeated intervention was performed if restenosis was detected. The stenotic sites were in eight cases the site of a previous subclavian venous line, and in one, the site of anatomic narrowing at the thoracic inlet of the subclavian vein. The technical success rate was 100%;a resulting complication was stent migration into the right atrium in one case in which a Hanaro stent had been used; this was removed by snaring. During follow-up of the eight patients in whon stent placement was successful, restenosis developed in three cases. This occurred during the 7th, 8th, and 15th month, respectively. Two such cases were treated by balloon dilatation. In hemodialytic shunt-related subclavian vein stenosis, treatment involving the use of a self-expandable metallic stent is useful, especially for treating a lesion which has not responded to angioplasty with a high patency rate

  5. Indoor metallic pollution related to mining activity in the Bolivian Altiplano

    International Nuclear Information System (INIS)

    Fonturbel, Francisco E.; Barbieri, Enio; Herbas, Cristian; Barbieri, Flavia L.; Gardon, Jacques

    2011-01-01

    The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children. - Highlights: → We measured polymetallic pollution in household indoor dust from a mining town. → Toxic elements (Pb, As, Cd, Sb) in dust are correlated, suggesting a common origin. → The most polluted houses are within a 1 km radius around the mining center. → Carrying mining workwear home increases indoor pollution. → Lead concentrations in dust represent a serious concern for Public Health (600 μg/g). - In a typical Andean mining city, the urban indoor pollution with toxic metallic elements is directly related to the closeness of the mining activities.

  6. Indoor metallic pollution related to mining activity in the Bolivian Altiplano

    Energy Technology Data Exchange (ETDEWEB)

    Fonturbel, Francisco E., E-mail: fonturbel@ug.uchile.cl [Departamento de Ciencias Ecologicas, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Barbieri, Enio [IRD-HSM (Institut de Recherche pour le Developpement), La Paz (Bolivia, Plurinational State of); Herbas, Cristian [Universidad Mayor de San Andres, IGEMA Institute (Instituto de Investigaciones Geologicas y del Medio Ambiente), La Paz (Bolivia, Plurinational State of); Barbieri, Flavia L.; Gardon, Jacques [IRD-HSM (Institut de Recherche pour le Developpement), La Paz (Bolivia, Plurinational State of); Universidad Mayor de San Andres, SELADIS Institute (Instituto de Servicios de Laboratorio para el Diagnostico e Investigacion en Salud), La Paz (Bolivia, Plurinational State of)

    2011-10-15

    The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children. - Highlights: > We measured polymetallic pollution in household indoor dust from a mining town. > Toxic elements (Pb, As, Cd, Sb) in dust are correlated, suggesting a common origin. > The most polluted houses are within a 1 km radius around the mining center. > Carrying mining workwear home increases indoor pollution. > Lead concentrations in dust represent a serious concern for Public Health (600 {mu}g/g). - In a typical Andean mining city, the urban indoor pollution with toxic metallic elements is directly related to the closeness of the mining activities.

  7. Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1997-01-01

    . In this study electron paramagnetic resonance spectroscopy with spin trapping has been used to identify radicals formed on collagen and related materials by metal ion-H2O2 mixtures. Attack of the hydroxyl radical, from a Fe(II)-H2O2 redox couple, on collagen peptides gave signals from both side chain (.CHR...... are similar to those from the alpha-carbon site of peptides and the side-chain of lysine. Enzymatic digestion of the large, protein-derived, species releases similar low-molecular-weight adducts. The metal ion employed has a dramatic effect on the species observed. With Cu(I)-H2O2 or Cu(II)-H2O2 instead of Fe(II)-H......2O2, evidence has been obtained for: i) altered sites of attack and fragmentation, ii) C-terminal decarboxylation, and iii) hydrogen abstraction at N-terminal alpha-carbon sites. This altered behaviour is believed to be due to the binding of copper ions to some substrates and hence site...

  8. Coloration of chromium-doped yttrium aluminum garnet single-crystal fibers using a divalent codopant

    International Nuclear Information System (INIS)

    Tissue, B.M.; Jia, W.; Lu, L.; Yen, W.M.

    1991-01-01

    We have grown single-crystal fibers of Cr:YAG and Cr,Ca:YAG under oxidizing and reducing conditions by the laser-heated-pedestal-growth method. The Cr:YAG crystals were light green due to Cr 3+ in octahedral sites, while the Cr,Ca:YAG crystals were brown. The presence of the divalent codopant was the dominant factor determining the coloration in these single-crystal fibers, while the oxidizing power of the growth atmosphere had little effect on the coloration. The Cr,Ca:YAG had a broad absorption band centered at 1.03 μm and fluoresced from 1.1 to 1.7 μm, with a room-temperature lifetime of 3.5 μs. The presence of both chromium and a divalent codopant were necessary to create the optically-active center which produces the near-infrared emission. Doping with only Ca 2+ created a different coloration with absorption in the blue and ultraviolet. The coloration in the Cr,Ca:YAG is attributed to Cr 4+ and is produced in as-grown crystals without irradiation or annealing, as has been necessary in previous work

  9. Higher cytotoxicity of divalent antibody-toxins than monovalent antibody-toxins

    International Nuclear Information System (INIS)

    Won, JaeSeon; Nam, PilWon; Lee, YongChan; Choe, MuHyeon

    2009-01-01

    Recombinant antibody-toxins are constructed via the fusion of a 'carcinoma-specific' antibody fragment to a toxin. Due to the high affinity and high selectivity of the antibody fragments, antibody-toxins can bind to surface antigens on cancer cells and kill them without harming normal cells [L.H. Pai, J.K. Batra, D.J. FitzGerald, M.C. Willingham, I. Pastan, Anti-tumor activities of immunotoxins made of monoclonal antibody B3 and various forms of Pseudomonas exotoxin, Proc. Natl. Acad. Sci. USA 88 (1991) 3358-3362]. In this study, we constructed the antibody-toxin, Fab-SWn-PE38, with SWn (n = 3, 6, 9) sequences containing n-time repeated (G 4 S) between the Fab fragment and PE38 (38 kDa truncated form of Pseudomonas exotoxin A). The SWn sequence also harbored one cysteine residue that could form a disulfide bridge between two Fab-SWn-PE38 monomers. We assessed the cytotoxicity of the monovalent (Fab-SWn-PE38), and divalent ([Fab-SWn-PE38] 2 ) antibody-toxins. The cytotoxicity of the dimer against the CRL1739 cell line was approximately 18.8-fold higher than that of the monomer on the ng/ml scale, which was approximately 37.6-fold higher on the pM scale. These results strongly indicate that divalency provides higher cytotoxicity for an antibody-toxin.

  10. SURVEY OF THE SPECTRA OF THE DIVALENT RARE EARTH IONS IN CUBIC CRYSTALS

    Energy Technology Data Exchange (ETDEWEB)

    McClure, Donald S. [Univ. of Chicago, IL (United States); Kiss, Zoltan J. [RCA Laboratories, Princeton, NJ (United States)

    1963-04-15

    The rare earth ions may exist in the divalent state in suitable host crystals such as CaF/sub 2/. All of the trivalent ions from La to Yb are reduced in situ to the divalent state in CaF/sub 2/ by gamma irradiation. The spectra of most of these ions show that the ground and first few excited states derive from f/sup n/ configurations, but the wesk absorption due to these is masked at higher energies by strong broad bands of the parity permitted f/sup n/ yields f/sup n-1/ d transitions. The excitation energy of these spectra have been calculated in a first approximation as the energy difference between the Hund Rule'' single determinant states of the configurations f/sup n -1/d and f/sup n/. This procedure satisfactorily accounts for the remarkable variations in the excitation energy in passing from one ion to the next in the series with the exception of Ge/ sup 2+/ Ce/sup 2+/, and Tb/sup 2+/, Ge/sup 2+/ probably has f/sup 7/d for its ground con figuration, while Ce/sup 2+/ and Tb/sup 2+/ are borderline cases. The spectral structure probably arises chiefly from the crystal field splitting of the d-orbital, since each ion in CaF/sub 2/ has a similar spectrum, and the spectra change drastically in sites of other than cubic symmetry. (auth)

  11. Androgen Receptor Antagonism By Divalent Ethisterone Conjugates In Castrate-Resistant Prostate Cancer Cells

    Science.gov (United States)

    Levine, Paul M.; Lee, Eugine; Greenfield, Alex; Bonneau, Richard; Logan, Susan K.; Garabedian, Michael J.; Kirshenbaum, Kent

    2013-01-01

    Sustained treatment of prostate cancer with Androgen Receptor (AR) antagonists can evoke drug resistance, leading to castrate-resistant disease. Elevated activity of the AR is often associated with this highly aggressive disease state. Therefore, new therapeutic regimens that target and modulate AR activity could prove beneficial. We previously introduced a versatile chemical platform to generate competitive and non-competitive multivalent peptoid oligomer conjugates that modulate AR activity. In particular, we identified a linear and a cyclic divalent ethisterone conjugate that exhibit potent anti-proliferative properties in LNCaP-abl cells, a model of castrate-resistant prostate cancer. Here, we characterize the mechanism of action of these compounds utilizing confocal microscopy, time-resolved fluorescence resonance energy transfer, chromatin immunoprecipitation, flow cytometry, and microarray analysis. The linear conjugate competitively blocks AR action by inhibiting DNA binding. In addition, the linear conjugate does not promote AR nuclear localization or co-activator binding. In contrast, the cyclic conjugate promotes AR nuclear localization and induces cell-cycle arrest, despite its inability to compete against endogenous ligand for binding to AR in vitro. Genome-wide expression analysis reveals that gene transcripts are differentially affected by treatment with the linear or cyclic conjugate. Although the divalent ethisterone conjugates share extensive chemical similarities, we illustrate that they can antagonize the AR via distinct mechanisms of action, establishing new therapeutic strategies for potential applications in AR pharmacology. PMID:22871957

  12. Divalent phosphate is a counterion for carboxyatractyloside-insensitive adenine nucleotide transport in rat liver mitochondria

    International Nuclear Information System (INIS)

    Nosek, M.T.; Aprille, J.R.

    1986-01-01

    Unidirectional, carboxyatractyloside(CAT)-insensitive adenine nucleotide (AdN) fluxes have been studied in isolated rat liver mitochondria (mito). Previous work has shown that ATP x Mg transport in one direction is coupled to ATP x Mg or P/sub i/ transport in the opposite direction. The purpose of this study was to determine whether divalent HPO 4 2- or monovalent H 2 PO 4 - is the transported phosphate species. The authors used the monofluorophosphate (PO 3 F 2- ) and difluorophosphate (PO 2 F 2 - ) analogues as potential counterions forAdN efflux. After a preincubation on ice with 14 C-ADP to label the matrix AdN, efflux was measured at 30 0 C, pH 7.4, in 225mM sucrose, 10mM KCl, 5mM MgCl 2 , 5mM glutamate, 5mM malate, 10mM Tris, 0.5mM P/sub i/, 1mM ATP, and 5μM CAT. With no other additions efflux was -0.62 +/- 0.20 nmole/minute/mg protein. The data supports the hypothesis that divalent but not monovalent phosphate can act as a counterion for ATPx Mg transport over this CAT-insensitive carrier

  13. Induction of divalent cation permeability by heterologous expression of a voltage sensor domain.

    Science.gov (United States)

    Arima, Hiroki; Tsutsui, Hidekazu; Sakamoto, Ayako; Yoshida, Manabu; Okamura, Yasushi

    2018-01-06

    The voltage sensor domain (VSD) is a protein domain that confers sensitivity to membrane potential in voltage-gated ion channels as well as the voltage-sensing phosphatase. Although VSDs have long been considered to function as regulatory units acting on adjacent effectors, recent studies have revealed the existence of direct ion permeation paths in some mutated VSDs and in the voltage-gated proton channel. In this study, we show that calcium currents are evoked upon membrane hyperpolarization in cells expressing a VSD derived from an ascidian voltage-gated ion channel superfamily. Unlike the previously reported omega-pore in the Shaker K + channel and rNav1.4, mutations are not required. From electrophysiological experiments in heterologous expression systems, we found that the conductance is directly mediated by the VSD itself and is carried by both monovalent and divalent cations. This is the first report of divalent cation permeation through a VSD-like structure. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Investigation Effect of Biorhythm on Work-Related Accidents in The Metal Industry (A Short Report

    Directory of Open Access Journals (Sweden)

    Ehsanollah Habibi

    2016-07-01

    Full Text Available Biorhythm is one of the newest subjects in the field of cognition of mental ergonomics which can be very effective in reduction of work-related accidents or mistakes with no apparent reason. With evaluating Biorhythm individuals can intervention action to reduce job accidents carried out. Thus, the aim of this study was to determine the relationship Biorhythm and work-related accidents in the metal industry. This research is a cross-sectional and analytical-descriptive in the metal industrial Isfahan city of 120 work-related accidents during 2015. The required information was collected from available documents in HSE unit of the company biorhythm charts were drawn based on a date of accidents and participants birthdays, using natural Biorhythm Software V3.02 Conduct. Finally، the data were analyzed using spss version 20 and descriptive statistics.This study showed that the frequency of accidents in critical days and negative section of physical cycle was more than expected. Also the frequency of accidents in critical days and negative section of emotional and intellectual cycles was less than expected. Most type of injury, including cuts to 35.8 percent and the lowest type of injury was torsion with 5 percent. Most limb injury, hands and fingers with 51.7 percent and the lowest limb injury were back at 2.5 percent. Accidents outbreak in physical cycles was 38.3 percent. These 120 accidents in additionally were causing 120 loss of working days in effect accident. Most percent of loss of working days were for 20 to 30 days with of 39.2 percent. Most percent of loss of working days were for 20 to 30 days with of 39.2 percent. Due to the physical nature of the work activities in the metal industry can be stated that the study showed that in physical work activities, frequency of accidents in critical days and negative section of physical cycle in which the person is not physically ready to do the job was more than expected. Therefore, by training

  15. Do galaxy global relationships emerge from local ones? The SDSS IV MaNGA surface mass density-metallicity relation

    Science.gov (United States)

    Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zhu, Guangtun B.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Law, David; Wake, David; Green, Jenny E.; Bizyaev, Dmitry; Oravetz, Daniel; Simmons, Audrey; Malanushenko, Elena; Pan, Kaike; Roman Lopes, Alexandre; Lane, Richard R.

    2016-12-01

    We present the stellar surface mass density versus gas metallicity (Σ*-Z) relation for more than 500 000 spatially resolved star-forming resolution elements (spaxels) from a sample of 653 disc galaxies included in the SDSS IV MaNGA survey. We find a tight relation between these local properties, with higher metallicities as the surface density increases. This relation extends over three orders of magnitude in the surface mass density and a factor of 4 in metallicity. We show that this local relationship can simultaneously reproduce two well-known properties of disc galaxies: their global mass-metallicity relationship and their radial metallicity gradients. We also find that the Σ*-Z relation is largely independent of the galaxy's total stellar mass and specific star formation rate (sSFR), except at low stellar mass and high sSFR. These results suggest that in the present-day universe local properties play a key role in determining the gas-phase metallicity in typical disc galaxies.

  16. A hidden variable in shear transformation zone volume versus Poisson's ratio relation in metallic glasses

    Science.gov (United States)

    Kim, S. Y.; Oh, H. S.; Park, E. S.

    2017-10-01

    Herein, we elucidate a hidden variable in a shear transformation zone (STZ) volume (Ω) versus Poisson's ratio (ν) relation and clarify the correlation between STZ characteristics and the plasticity of metallic glasses (MGs). On the basis of cooperative shear model and atomic stress theories, we carefully formulate Ω as a function of molar volume (Vm) and ν. The twofold trend in Ω and ν is attributed to a relatively large variation of Vm as compared to that of ν as well as an inverse relation between Vm and ν. Indeed, the derived equation reveals that the number of atoms in an STZ instead of Ω is a microstructural characteristic which has a close relationship with plasticity since it reflects the preference of atomistic behaviors between cooperative shearing and the generation of volume strain fluctuation under stress. The results would deepen our understanding of the correlation between microscopic behaviors (STZ activation) and macroscopic properties (plasticity) in MGs and enable a quantitative approach in associating various STZ-related macroscopic behaviors with intrinsic properties of MGs.

  17. Structural studies of metal oxides related to High-Tc superconductors

    International Nuclear Information System (INIS)

    Hjorth, M.

    1990-02-01

    The project was started in order to investigate metal oxide structures related in some way to high-T c superconductors, using the crystallographic methods available; and in order to be able to use crystallographic methods in ways that go beyond routine applications in order to contribute to the crystallographic knowledge concerning these oxides. The project goes a step outside the boarders normally defined by using the term ''high-T c superconductors'', thus studying metal oxides from a more general crystallographic viewpoint. The methods used are the expansions of the spherical atom model, and of the thermal probability density function, and combination of X-ray work with high resolution electron microscopy. The use of the expanded diffraction models presents problems such as bad convergence in least squares refinement, physical unreasonable parameters, problems with interpretation of the results and difficulties due to missing or insufficient computer programs. The use of these models is discussed. Dynamical theory is applied when considering electron diffraction results. The theory is presented, focusing on the modifications of the standard theory used for some of the structures considered in the thesis, and in overview on other theoretical topics is given. A presentation is given of the structures which have been considered and of earlier work on related compounds, of the problems and solutions applied to the compound discussed and of the results obtained. The results are discussed. The appendices describe published papers and the work not directly connected to the main topics, e.g. implementation and development of computer programs. (AB) 172 refs

  18. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    International Nuclear Information System (INIS)

    Wilczek, Grazyna; Babczynska, Agnieszka; Augustyniak, Maria; Migula, Pawel

    2004-01-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex

  19. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    Energy Technology Data Exchange (ETDEWEB)

    Wilczek, Grazyna [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Babczynska, Agnieszka [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Augustyniak, Maria [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland); Migula, Pawel [Department of Animal Physiology and Ecotoxicology, University of Silesia, Bankowa 9, 40-007 Katowice (Poland)]. E-mail: migula@us.edu.pl

    2004-12-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex.

  20. Acute effects of heavy metals on the expression of glutathione-related antioxidant genes in the marine ciliate Euplotes crassus

    International Nuclear Information System (INIS)

    Kim, Se-Hun; Kim, Se-Joo; Lee, Jae-Seong; Lee, Young-Mi

    2014-01-01

    Highlights: • Significant higher increases in the relative ROS and total GSH levels were observed after exposure to heavy metals. • Real-time PCR data showed expression levels of GPx and GR mRNA were sensitively modulated within 8 h of exposure to heavy metals. • E. crassus GPx and GR genes may be involved in cellular defense mechanisms against heavy metal-induced oxidative stress. • E. crassus GPx and GR genes will be useful as potential molecular markers for monitoring heavy metal contamination. - Abstract: Euplotes crassus, a single-celled eukaryote, is directly affected by environmental contaminants. Here, exponentially cultured E. crassus were exposed to cadmium, copper, lead, and zinc and then the reactive oxygen species (ROS) and total glutathione (GSH) levels were measured. Subsequently, the transcriptional modulation of glutathione peroxidase (GPx) and glutathione reductase (GR) were estimated by quantitative RT-PCR. After an 8-h exposure, significantly higher increases in the relative ROS and total GSH levels were observed in exposed group, compared to the controls. Real-time PCR data revealed that the expression levels of GPx and GR mRNA were sensitively modulated within 8 h of exposure to all heavy metals. These findings suggest that these genes may be involved in cellular defense mechanisms by modulating their gene expression against heavy metal-induced oxidative stress. Thus, they may be useful as potential molecular biomarkers to assess sediment environments for contaminants

  1. THE REDSHIFT EVOLUTION OF THE RELATION BETWEEN STELLAR MASS, STAR FORMATION RATE, AND GAS METALLICITY OF GALAXIES

    International Nuclear Information System (INIS)

    Niino, Yuu

    2012-01-01

    We investigate the relation between stellar mass (M * ), star formation rate (SFR), and metallicity (Z) of galaxies, the so-called fundamental metallicity relation, in the galaxy sample of the Sloan Digital Sky Survey Data Release 7. We separate the galaxies into narrow redshift bins and compare the relation at different redshifts and find statistically significant (>99%) evolution. We test various observational effects that might cause seeming Z evolution and find it difficult to explain the evolution of the relation only by the observational effects. In the current sample of low-redshift galaxies, galaxies with different M * and SFR are sampled from different redshifts, and there is degeneracy between M * /SFR and redshift. Hence, it is not straightforward to distinguish a relation between Z and SFR from a relation between Z and redshift. The separation of the intrinsic relation from the redshift evolution effect is a crucial issue in the understanding of the evolution of galaxies.

  2. Relations between variously available fractions of trace metals in the soil and their actual plant-uptake

    International Nuclear Information System (INIS)

    Bujtas, K.; Csillag, J.

    1999-01-01

    In a pot experiment, availabilities of Cd, Cr, Ni, Pb, and Zn added to the soil as metal nitrates or as enrichment of sewage sludge were evaluated by comparing concentrations of their total potentially available, presumably plant-available and directly plant-available forms in the soil. At excessively increasing soil contamination, the plant-available concentrations increased more than the total soil contents, thus the relative availabilities of the metals increased. This was reflected in the amounts taken up by the young maize test plants and in the plant/soil transfer factors. Transfer factors calculated for the 'plant-available' soil metal contents depended less on the contamination level than those based on total soil metal contents. Refs. 8 (author)

  3. On a New Theoretical Framework for RR Lyrae Stars. II. Mid-infrared Period–Luminosity–Metallicity Relations

    Energy Technology Data Exchange (ETDEWEB)

    Neeley, Jillian R.; Marengo, Massimo; Trueba, Nicolas [Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Bono, Giuseppe; Braga, Vittorio F.; Magurno, Davide [Department of Physics, Università di Roma Tor Vergara, via della Ricerca Scientifica 1, I-00133 Roma (Italy); Dall’Ora, Massimo; Marconi, Marcella [INAF-Osservatorio Astronomico di Capodimonte, Salita Moiarello 16, I-80131 Napoli (Italy); Tognelli, Emanuele; Moroni, Pier G. Prada [Dipartimento di Fisica, Università di Pisa, Lago Bruno Pontecorvo 3, I-56127, Pisa (Italy); Beaton, Rachael L.; Madore, Barry F.; Seibert, Mark [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Freedman, Wendy L. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Monson, Andrew J. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Scowcroft, Victoria [Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Stetson, Peter B., E-mail: jrneeley@iastate.edu [NRC-Herzberg, Dominion Astrophysical Observatory, 5071 West Saanich Road, Victoria BC V9E 2E7 (Canada)

    2017-06-01

    We present new theoretical period–luminosity–metallicity (PLZ) relations for RR Lyræ stars (RRLs) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad range of metal abundances ( Z = 0.0001–0.0198). In deriving the light curves, we tested two sets of atmospheric models and found no significant difference between the resulting mean magnitudes. We also compare our theoretical relations to empirical relations derived from RRLs in both the field and in the globular cluster M4. Our theoretical PLZ relations were combined with multi-wavelength observations to simultaneously fit the distance modulus, μ {sub 0}, and extinction, A {sub V}, of both the individual Galactic RRL and of the cluster M4. The results for the Galactic RRL are consistent with trigonometric parallax measurements from Gaia ’ s first data release. For M4, we find a distance modulus of μ {sub 0} = 11.257 ± 0.035 mag with A {sub V}= 1.45 ± 0.12 mag, which is consistent with measurements from other distance indicators. This analysis has shown that, when considering a sample covering a range of iron abundances, the metallicity spread introduces a dispersion in the PL relation on the order of 0.13 mag. However, if this metallicity component is accounted for in a PLZ relation, the dispersion is reduced to ∼0.02 mag at mid-infrared wavelengths.

  4. Relating Magnetic Parameters to Heavy Metal Concentrations and Environmental Factors at Formosa Mine Superfund Site, Douglas County, OR

    Science.gov (United States)

    Upton, T. L.

    2016-12-01

    Advances in the field of environmental magnetism have led to exciting new applications for this field. Magnetic minerals are ubiquitous in the environment and tend to have an affinity for heavy metals. Hence, it has been demonstrated that magnetic properties are often significantly related to concentrations of heavy metals and other pollutants. As a result, magnetic techniques have been used as proxy for determining hot spots of several types of pollution produced from a diversity of anthropogenic sources. Magnetic measurements are non-destructive and relatively inexpensive compared to geochemical analyses. The utility of environmental magnetic methods varies widely depending on biological, chemical and physical processes that create and transform soils and sediments. Applications in the direction of mapping heavy metals have been studied and shown to be quite useful in countries such as China and India but to date, little research has been done in the US. As such, there is need to expand the scope of research to a wider range of soil types and land uses, especially within the US. This study investigates the application of environmental magnetic techniques to mapping of heavy metal concentrations at the Formosa Mine Superfund Site, an abandoned mine about 25 miles southwest of Roseburg, OR. The soils and sediment at this site are derived from pyrite-rich bedrock which is weak in terms of magnetic susceptibility. Using hotspot analysis, correlation and cluster analyses, interactions between metals and magnetic parameters are investigated in relation to environmental factors such as proximity to seeps and adits. Preliminary results suggest significant correlation of magnetic susceptibility with certain heavy metals, signifying that magnetic methods may be useful in mapping heavy metal hotspots at this site. Further analysis examines the relation of various land use differences in magnetic signatures obtained throughout the Cow Creek watershed.

  5. The effects of monovalent and divalent cations on the stability of silver nanoparticles formed from direct reduction of silver ions by Suwannee River humic acid/natural organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Akaighe, Nelson [Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Depner, Sean W.; Banerjee, Sarbajit [Department of Chemistry, 410 Natural Sciences Complex, University at Buffalo, The State University of New York, Buffalo, NY 14260-3000 (United States); Sharma, Virender K. [Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States); Sohn, Mary, E-mail: msohn@fit.edu [Chemistry Department, Florida Institute of Technology, 150 West University Boulevard, Melbourne, FL 32901 (United States)

    2012-12-15

    The formation and characterization of AgNPs (silver nanoparticles) formed from the reduction of Ag{sup +} by SRNOM (Suwannee River natural organic matter) is reported. The images of SRNOM-formed AgNPs and the selected area electron diffraction (SAED) were captured by high resolution transmission electron microscopy (HRTEM). The colloidal and chemical stability of SRNOM- and SRHA (Suwannee River humic acid)-formed AgNPs in different ionic strength solutions of NaCl, KCl, CaCl{sub 2} and MgCl{sub 2} was investigated in an effort to evaluate the key fate and transport processes of these nanoparticles in natural aqueous environments. The aggregation state, stability and sedimentation rate of the AgNPs were monitored by Dynamic Light Scattering (DLS), zeta potential, and UV-vis measurements. The results indicate that both types of AgNPs are very unstable in high ionic strength solutions. Interestingly, the nanoparticles appeared more unstable in divalent cation solutions than in monovalent cation solutions at similar concentrations. Furthermore, the presence of SRNOM and SRHA contributed to the nanoparticle instability at high ionic strength in divalent metallic cation solutions, most likely due to intermolecular bridging with the organic matter. The results clearly suggest that changes in solution chemistry greatly affect nanoparticle long term stability and transport in natural aqueous environments. Highlights: Black-Right-Pointing-Pointer Formation of SRNOM-AgNPs under environmentally relevant conditions Black-Right-Pointing-Pointer Influence of monovalent versus divalent cations on SRHA- and SRNOM-AgNP stability Black-Right-Pointing-Pointer Effect of AgNPs on organic matter removal from water columns.

  6. Bioaccessibility of metal cations in soil is linearly related to its water exchange rate constant.

    Science.gov (United States)

    Laird, Brian D; Peak, Derek; Siciliano, Steven D

    2011-05-01

    Site-specific risk assessments often incorporate the concepts of bioaccessibility (i.e., contaminant fraction released into gastrointestinal fluids) or bioavailability (i.e., contaminant fraction absorbed into systemic circulation) into the calculation of ingestion exposure. We evaluated total and bioaccessible metal concentrations for 19 soil samples under simulated stomach and duodenal conditions using an in vitro gastrointestinal model. We demonstrated that the median bioaccessibility of 23 metals ranged between exchange rates of metal cations (k(H₂O)) indicated that desorption kinetics may influence if not control metal bioaccessibility.

  7. Acidic pH and divalent cation sensing by PhoQ are dispensable for systemic salmonellae virulence.

    Science.gov (United States)

    Hicks, Kevin G; Delbecq, Scott P; Sancho-Vaello, Enea; Blanc, Marie-Pierre; Dove, Katja K; Prost, Lynne R; Daley, Margaret E; Zeth, Kornelius; Klevit, Rachel E; Miller, Samuel I

    2015-05-23

    Salmonella PhoQ is a histidine kinase with a periplasmic sensor domain (PD) that promotes virulence by detecting the macrophage phagosome. PhoQ activity is repressed by divalent cations and induced in environments of acidic pH, limited divalent cations, and cationic antimicrobial peptides (CAMP). Previously, it was unclear which signals are sensed by salmonellae to promote PhoQ-mediated virulence. We defined conformational changes produced in the PhoQ PD on exposure to acidic pH that indicate structural flexibility is induced in α-helices 4 and 5, suggesting this region contributes to pH sensing. Therefore, we engineered a disulfide bond between W104C and A128C in the PhoQ PD that restrains conformational flexibility in α-helices 4 and 5. PhoQ(W104C-A128C) is responsive to CAMP, but is inhibited for activation by acidic pH and divalent cation limitation. phoQ(W104C-A128C) Salmonella enterica Typhimurium is virulent in mice, indicating that acidic pH and divalent cation sensing by PhoQ are dispensable for virulence.

  8. Interaction of divalent minerals with liposoluble nutrients and phytochemicals during digestion and influences on their bioavailability - a review.

    Science.gov (United States)

    Corte-Real, Joana; Bohn, Torsten

    2018-06-30

    Several divalent minerals, including the macroelements calcium and magnesium, are essential nutrients for humans. However, their intake, especially via high-dose supplements, has been suspected to reduce the availability of lipophilic dietary constituents, including lipids, liposoluble vitamins, and several phytochemicals such as carotenoids. These constituents require emulsification in order to be bioavailable, and high divalent mineral concentrations may perturb this process, due to precipitations of free fatty acids or bile salt complexation, both pivotal for mixed micelle formation. Though in part based on in vitro or indirect evidence, it appears likely that high-dose supplements of divalent minerals around or even below their recommended dietary allowance perturb the availability of certain liposoluble miroconstituents, in addition to reducing absorption of dietary lipids/cholesterol. In this review, we investigate possible negative influences of divalent minerals, including trace elements (iron, zinc), on the digestion and intestinal uptake of lipophilic dietary constituents, with a focus on carotenoids. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  10. Chemical speciation of heavy metals in sandy soils in relation to availability and mobility

    NARCIS (Netherlands)

    Temminghoff, E.J.M.

    1998-01-01

    The environmental risk of heavy metals which are present in soil at a certain total content is highly dependent on soil properties. Chemical speciation is a comprehensive term for the distribution of heavy metals over all possible chemical forms (species) in soil solution and in the solid

  11. ELECTED PROBLEMS RELATED TO ENVIRONMENTAL HEAVY METALS EXPOSURE AND CHELATION THERAPY

    Directory of Open Access Journals (Sweden)

    Anna Skoczyńska

    2010-09-01

    Full Text Available Background: Exposure to heavy metals leads to functional and metabolic disturbances and many of them are included in pathogenesis of common diseases (arterial hypertension, atherosclerosis, neurodegenerative processes. In this context new therapeutic and prophylactic strategies are necessary. Patients diagnosed with chronic heavy metals intoxication usually require chelation to increase mobilisation of metals from tissues and elimination of them via urine. Acute poisoning with toxic metal may be difficult to diagnosis, especially in case of accidental intoxication or suicidal intention. Patients also require chelation after causative factor is identified. Objectives: To describe some problems connected with toxicity of metals poisoning and to review pharmacologic therapies that could have a role in poisoning with metals. Methods: A review of the literature was carried out and expert opinion expressed. Results/conclusion: Chelation is a common therapy in case of poisoning with toxic metals but it is satisfied only partially. A combined therapy with structurally different chelators or long-term acting chelators could become viable alternatives in the future. A combined therapy with an antioxidant plus chelator may be a good choice in patients chronically poisoned with metals. Exposure to lead should be taken into account during estimation of global cardiovascular risk.

  12. Perspective on Structural Evolution and Relations with Thermophysical Properties of Metallic Liquids.

    Science.gov (United States)

    Wang, Xiao-Dong; Jiang, Jian-Zhong

    2017-11-01

    The relationship between the structural evolution and properties of metallic liquids is a long-standing hot issue in condensed-matter physics and materials science. Here, recent progress is reviewed in several fundamental aspects of metallic liquids, including the methods to study their atomic structures, liquid-liquid transition, physical properties, fragility, and their correlations with local structures, together with potential applications of liquid metals at room temperature. Involved with more experimentally and theoretically advanced techniques, these studies provide more in-depth understanding of the structure-property relationship of metallic liquids and promote the design of new metallic materials with superior properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Fluorescent Protein-Based Ca2+ Sensor Reveals Global, Divalent Cation-Dependent Conformational Changes in Cardiac Troponin C.

    Directory of Open Access Journals (Sweden)

    Myriam A Badr

    Full Text Available Cardiac troponin C (cTnC is a key effector in cardiac muscle excitation-contraction coupling as the Ca2+ sensing subunit responsible for controlling contraction. In this study, we generated several FRET sensors for divalent cations based on cTnC flanked by a donor fluorescent protein (CFP and an acceptor fluorescent protein (YFP. The sensors report Ca2+ and Mg2+ binding, and relay global structural information about the structural relationship between cTnC's N- and C-domains. The sensors were first characterized using end point titrations to decipher the response to Ca2+ binding in the presence or absence of Mg2+. The sensor that exhibited the largest responses in end point titrations, CTV-TnC, (Cerulean, TnC, and Venus was characterized more extensively. Most of the divalent cation-dependent FRET signal originates from the high affinity C-terminal EF hands. CTV-TnC reconstitutes into skinned fiber preparations indicating proper assembly of troponin complex, with only ~0.2 pCa unit rightward shift of Ca2+-sensitive force development compared to WT-cTnC. Affinity of CTV-TnC for divalent cations is in agreement with known values for WT-cTnC. Analytical ultracentrifugation indicates that CTV-TnC undergoes compaction as divalent cations bind. C-terminal sites induce ion-specific (Ca2+ versus Mg2+ conformational changes in cTnC. Our data also provide support for the presence of additional, non-EF-hand sites on cTnC for Mg2+ binding. In conclusion, we successfully generated a novel FRET-Ca2+ sensor based on full length cTnC with a variety of cellular applications. Our sensor reveals global structural information about cTnC upon divalent cation binding.

  14. Data-driven modeling of background and mine-related acidity and metals in river basins

    Science.gov (United States)

    Friedel, Michael J

    2013-01-01

    A novel application of self-organizing map (SOM) and multivariate statistical techniques is used to model the nonlinear interaction among basin mineral-resources, mining activity, and surface-water quality. First, the SOM is trained using sparse measurements from 228 sample sites in the Animas River Basin, Colorado. The model performance is validated by comparing stochastic predictions of basin-alteration assemblages and mining activity at 104 independent sites. The SOM correctly predicts (>98%) the predominant type of basin hydrothermal alteration and presence (or absence) of mining activity. Second, application of the Davies–Bouldin criteria to k-means clustering of SOM neurons identified ten unique environmental groups. Median statistics of these groups define a nonlinear water-quality response along the spatiotemporal hydrothermal alteration-mining gradient. These results reveal that it is possible to differentiate among the continuum between inputs of background and mine-related acidity and metals, and it provides a basis for future research and empirical model development.

  15. Measuring hypoxia induced metal release from highly contaminated estuarine sediments during a 40 day laboratory incubation experiment

    Energy Technology Data Exchange (ETDEWEB)

    Banks, Joanne L., E-mail: jlbanks@student.unimelb.edu.au [Department of Zoology, University of Melbourne, Victoria, 3010 Australia (Australia); Ross, D. Jeff, E-mail: Jeff.Ross@utas.edu.au [Institute of Marine and Antarctic Studies, Nubeena Crescent, Taroona, Tasmania, 7053 Australia (Australia); Keough, Michael J., E-mail: mjkeough@unimelb.edu.au [Department of Zoology, University of Melbourne, Victoria, 3010 Australia (Australia); Eyre, Bradley D., E-mail: bradley.eyre@scu.edu.au [Centre for Coastal Biogeochemistry, School of Environmental Science and Management, Southern Cross University, PO Box 157, Lismore, NSW, 2480 Australia (Australia); Macleod, Catriona K., E-mail: Catriona.Macleod@utas.edu.au [Institute of Marine and Antarctic Studies, Nubeena Crescent, Taroona, Tasmania, 7053 Australia (Australia)

    2012-03-15

    Nutrient inputs to estuarine and coastal waters worldwide are increasing and this in turn is increasing the prevalence of eutrophication and hypoxic and anoxic episodes in these systems. Many urbanised estuaries are also subject to high levels of anthropogenic metal contamination. Environmental O{sub 2} levels may influence whether sediments act as sinks or sources of metals. In this study we investigated the effect of an extended O{sub 2} depletion event (40 days) on fluxes of trace metals (and the metalloid As) across the sediment-water interface in sediments from a highly metal contaminated estuary in S.E. Tasmania, Australia. We collected sediments from three sites that spanned a range of contamination and measured total metal concentration in the overlying water using sealed core incubations. Manganese and iron, which are known to regulate the release of other divalent cations from sub-oxic sediments, were released from sediments at all sites as hypoxia developed. In contrast, the release of arsenic, cadmium, copper and zinc was comparatively low, most likely due to inherent stability of these elements within the sediments, perhaps as a result of their refractory origin, their association with fine-grained sediments or their being bound in stable sulphide complexes. Metal release was not sustained due to the powerful effect of metal-sulphide precipitation of dissolved metals back into sediments. The limited mobilisation of sediment bound metals during hypoxia is encouraging, nevertheless the results highlight particular problems for management in areas where hypoxia might occur, such as the release of metals exacerbating already high loads or resulting in localised toxicity. - Highlights: Black-Right-Pointing-Pointer Metal contaminated sediments exposed to long-term hypoxia released Mn and Fe pulses. Black-Right-Pointing-Pointer As flux increased under anoxic conditions Cd, Cu and Zn fluxes occurred only during the first week of hypoxia. Black

  16. Measuring hypoxia induced metal release from highly contaminated estuarine sediments during a 40 day laboratory incubation experiment

    International Nuclear Information System (INIS)

    Banks, Joanne L.; Ross, D. Jeff; Keough, Michael J.; Eyre, Bradley D.; Macleod, Catriona K.

    2012-01-01

    Nutrient inputs to estuarine and coastal waters worldwide are increasing and this in turn is increasing the prevalence of eutrophication and hypoxic and anoxic episodes in these systems. Many urbanised estuaries are also subject to high levels of anthropogenic metal contamination. Environmental O 2 levels may influence whether sediments act as sinks or sources of metals. In this study we investigated the effect of an extended O 2 depletion event (40 days) on fluxes of trace metals (and the metalloid As) across the sediment–water interface in sediments from a highly metal contaminated estuary in S.E. Tasmania, Australia. We collected sediments from three sites that spanned a range of contamination and measured total metal concentration in the overlying water using sealed core incubations. Manganese and iron, which are known to regulate the release of other divalent cations from sub-oxic sediments, were released from sediments at all sites as hypoxia developed. In contrast, the release of arsenic, cadmium, copper and zinc was comparatively low, most likely due to inherent stability of these elements within the sediments, perhaps as a result of their refractory origin, their association with fine-grained sediments or their being bound in stable sulphide complexes. Metal release was not sustained due to the powerful effect of metal-sulphide precipitation of dissolved metals back into sediments. The limited mobilisation of sediment bound metals during hypoxia is encouraging, nevertheless the results highlight particular problems for management in areas where hypoxia might occur, such as the release of metals exacerbating already high loads or resulting in localised toxicity. - Highlights: ► Metal contaminated sediments exposed to long-term hypoxia released Mn and Fe pulses. ► As flux increased under anoxic conditions Cd, Cu and Zn fluxes occurred only during the first week of hypoxia. ► Flux of these metals from 3 sites was not related to total sediment metal

  17. Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures.

    Science.gov (United States)

    Piacenza, Elena; Presentato, Alessandro; Turner, Raymond J

    2018-02-25

    In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids, DNA, and polysaccharides) or secondary metabolites (e.g. flavonoids, terpenoids, glycosides, organic acids, and alkaloids) naturally produced by organisms have been indicated as main contributors to the stabilization of Bio-Me-nanostructures. Nevertheless, the chemical-physical mechanisms behind the ability of these molecules in providing stability to Bio-Me-nanomaterials are unknown. In this context, transposing the stabilization theory of chemically synthesized Me-nanomaterials (Ch-Me-nanomaterials) to biogenic materials can be used towards a better comprehension of macromolecules and secondary metabolites role as stabilizing agents of Bio-Me-nanomaterials. According to this theory, nanomaterials are generally featured by high thermodynamic instability in suspension, due to their high surface area and surface energy. This feature leads to the necessity to stabilize chemical nanostructures, even during or directly after their synthesis, through the development of (i) electrostatic, (ii) steric, or (iii) electrosteric interactions occurring between molecules and nanomaterials in suspension. Based on these three mechanisms, this review is focused on parallels between the stabilization of biogenic or chemical nanomaterials, suggesting which chemical-physical mechanisms may be

  18. Dielectric relaxations in non-metallic materials related to Y-Ba-Cu-O superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bennani, H.; Pilet, J.C. (Lab. Instrumentation, Rennes-1 Univ., 35 (France)); Guilloux-Viry, M.; Perrin, C.; Perrin, A.; Sergent, M. (Lab. de Chimie Minerale B, C.N.R.S., 35 - Rennes (France))

    1990-10-15

    In relation with high Tc superconducting material studies, dielectric measurements have been carried out, in the frequency range 10 Hz - 100 kHz, on two powdered compounds belonging to the Y-Ba-Cu-O system. The non-metallic tetragonal phases YBa{sub 2}Cu{sub 3}O{sub 6+x} exhibit dielectric relaxations: for the studied samples (x<0.4) the activation energy U is observed in the range 0.5related to the presence of electrical dipoles due to the local dissymmetries induced by oxygen vacancies in the Cu-O chains. The insulating green phase Y{sub 2}BaCuO{sub 5} has a lower activation energy U {approx equal} 0.4 eV and an entropy factor A {approx equal} 10{sup 10} Hz. A second dielectric relaxation has been detected at higher temperature, near 400 K. Additional measurements to 77 K at 1 MHz give a value of dielectric constant {epsilon}'=3 and a low loss factor tg{delta}=10{sup -3}: this latter value is comparable to the one of lanthanum gallate recently proposed as a substrate for high frequency uses. This result enhances the previously reported potential interest of this material as substrate or buffer layer for preparation of superconducting thin films for high frequency applications. (orig.).

  19. Quantitation of maxillary remodeling. 1. A description of osseous changes relative to superimposition on metallic implants.

    Science.gov (United States)

    Baumrind, S; Korn, E L; Ben-Bassat, Y; West, E E

    1987-01-01

    Lateral skull radiographs for a set of 31 human subjects were examined using computer-aided methods in an attempt to quantify modal trends of maxillary remodeling during the mixed dentition and adolescent growth periods. Cumulative changes in position of anterior nasal spine (ANS), posterior nasal spine (PNS), and Point A are reported at annual intervals relative to superimposition on previously placed maxillary metallic implants. This in vivo longitudinal study confirms at a high level of confidence earlier findings by Enlow, Björk, Melsen, and others to the effect that the superior surface of the maxilla remodels downward during the period of growth and development being investigated. However, the inter-individual variability is relatively large, the mean magnitudes of change are relatively small, and the rate of change appears to diminish by 13.5 years. For the 19 subjects for whom data were available for the time interval from 8.5 to 15.5 years, mean downward remodeling at PNS was 2.50 mm with a standard deviation of 2.23 mm. At ANS, corresponding mean value was 1.56 mm with a standard deviation of 2.92 mm. Mean rotation of the ANS-PNS line relative to the implant line was 1.1 degree in the "forward" direction. However, this rotational change was particularly variable with a standard deviation of 4.6 degrees and a range of 11.3 degrees "forward" to 6.7 degrees "backward." The study provides strong evidence that the palate elongates anteroposteriorly mainly by the backward remodeling of structures located posterior to the region in which the implants were placed. There is also evidence that supports the idea of modal resorptive remodeling at ANS and PNS, but here the data are somewhat more equivocal. It appears likely, but not certain, that there are real differences in the modal patterns of remodeling between treated and untreated subjects. Because of problems associated with overfragmentation of the sample, sex differences were not investigated.

  20. Heavy metals in wild house mice from coal-mining areas of Colombia and expression of genes related to oxidative stress, DNA damage and exposure to metals.

    Science.gov (United States)

    Guerrero-Castilla, Angélica; Olivero-Verbel, Jesús; Marrugo-Negrete, José

    2014-03-01

    Coal mining is a source of pollutants that impact on environmental and human health. This study examined the metal content and the transcriptional status of gene markers associated with oxidative stress, metal transport and DNA damage in livers of feral mice collected near coal-mining operations, in comparison with mice obtained from a reference site. Mus musculus specimens were caught from La Loma and La Jagua, two coal-mining sites in the north of Colombia, as well as from Valledupar (Cesar Department), a city located 100km north of the mines. Concentrations in liver tissue of Hg, Zn, Pb, Cd, Cu and As were determined by differential stripping voltammetry, and real-time PCR was used to measure gene expression. Compared with the reference group (Valledupar), hepatic concentrations of Cd, Cu and Zn were significantly higher in animals living near mining areas. In exposed animals, the mRNA expression of NQ01, MT1, SOD1, MT2, and DDIT3 was 4.2-, 7.3-, 2.5-, 4.6- and 3.4-fold greater in coal mining sites, respectively, than in animals from the reference site (pmining may generate pollutants that could affect the biota, inducing the transcription of biochemical markers related to oxidative stress, metal exposure, and DNA damage. These changes may be in part linked to metal toxicity, and could have implications for the development of chronic disease. Therefore, it is essential to implement preventive measures to minimize the effects of coal mining on its nearby environment, in order to protect human health. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Modeling Ethanol Decomposition on Transition Metals: A Combined Application of Scaling and Bronsted-Evans-Polanyi Relations

    DEFF Research Database (Denmark)

    Ferrin, P.; Simonetti, D.; Kandoi, S.

    2009-01-01

    calculations necessary to describe trends in activity and selectivity across metal and alloy surfaces, thus extending the reach of DFT to more complex systems. In-this work, the well-known family of Bronsted-Evans-Polanyi (BEP) correlations, connecting minima with maxima in the potential energy surface...... on a subset of these surfaces are calculated. Experiments on supported catalysts verify that this simple model is reasonably accurate in describing reactivity trends across metals, suggesting that the combination of BEP and scaling relations may substantially reduce the cost of DFT calculations required...

  2. Dining at the periodic table: metals concentrations as they relate to recycling.

    Science.gov (United States)

    Johnson, Jeremiah; Harper, E M; Lifset, Reid; Graedel, T E

    2007-03-01

    A correlation between the prices of a variety of substances and their dilutions in their initial matrices was shown in 1959 by T.K. Sherwood. The research presented here shows that the relationship holds for engineering metals today, which we termed the metals-specific Sherwood plot. The concentrations of metals in products (e.g., printed wiring boards and automobiles) and waste streams (e.g., municipal solid waste, and construction and demolition debris) were plotted with this correlation. In addition, for the products and waste streams that undergo disassembly at end-of-life, the metals concentrations of the disassembled components were also plotted. It was found that most of the metals that are currently targeted for recycling have post-disassembly concentrations that lie above the metals-specific Sherwood plot (i.e., have concentrations that are more enriched than minimum profitable ore grades). This suggests that material concentration plays a role in the viability of recycling at end-of-life. As products grow in complexity and the variety of materials used, analyses such as this one provide insight for policymakers and those interested in material sustainability into macro-level trends of material use and future recycling practices.

  3. Monitoring Heavy Metal Contents with Sphagnum Junghuhnianum Moss Bags in Relation to Traffic Volume in Wuxi, China

    Directory of Open Access Journals (Sweden)

    Rong Hu

    2018-02-01

    Full Text Available Despite its small size, a moss bag can reveal the different temporal and spatial deposition patterns of pollutants at a particular site; therefore, researchers can use moss bags to determine pollution sources and to put forward strategies for pollution control. Although the use of moss bags to monitor atmospheric pollution has been widely reported in Europe, there are few such empirical studies in China. Thus, in this study, bags containing the moss Sphagnum junghuhnianum were used to assess the concentrations of heavy metals (chromium (Cr, copper (Cu, lead (Pb, vanadium (V, and zinc (Zn at five sampling sites (four roads and a forest park during the summer and winter of 2012. According to the relative accumulation factor (RAF and contamination factor (CF results, pollution in winter was heavier than that in summer, and Cr was found to be the most contaminating, having the highest mean CF. There was a significant positive correlation (p < 0.05 between traffic volume and concentration for three heavy metals (Cr, Cu, and V in winter, whereas a significant positive correlation (p < 0.05 was observed between traffic volume and concentrations for four heavy metal elements (Cr, Pb, V, and Zn in summer, indicating a close relationship between heavy metal contents and traffic volume. Although there was substantial variation in the concentrations of the five heavy metals in the moss bags, significant correlations between heavy metals suggested that the contaminants originated from a common source, namely vehicle emissions. The results demonstrated that the four roads were subject to different degrees of pollution depending on the volume of traffic using each road. Therefore, the results of this study suggest that traffic volume is a major reason for heavy metal pollution.

  4. Monitoring Heavy Metal Contents with Sphagnum Junghuhnianum Moss Bags in Relation to Traffic Volume in Wuxi, China.

    Science.gov (United States)

    Hu, Rong; Yan, Yun; Zhou, Xiaoli; Wang, Yanan; Fang, Yanming

    2018-02-22

    Despite its small size, a moss bag can reveal the different temporal and spatial deposition patterns of pollutants at a particular site; therefore, researchers can use moss bags to determine pollution sources and to put forward strategies for pollution control. Although the use of moss bags to monitor atmospheric pollution has been widely reported in Europe, there are few such empirical studies in China. Thus, in this study, bags containing the moss Sphagnum junghuhnianum were used to assess the concentrations of heavy metals (chromium (Cr), copper (Cu), lead (Pb), vanadium (V), and zinc (Zn)) at five sampling sites (four roads and a forest park) during the summer and winter of 2012. According to the relative accumulation factor (RAF) and contamination factor (CF) results, pollution in winter was heavier than that in summer, and Cr was found to be the most contaminating, having the highest mean CF. There was a significant positive correlation ( p heavy metals (Cr, Cu, and V) in winter, whereas a significant positive correlation ( p heavy metal elements (Cr, Pb, V, and Zn) in summer, indicating a close relationship between heavy metal contents and traffic volume. Although there was substantial variation in the concentrations of the five heavy metals in the moss bags, significant correlations between heavy metals suggested that the contaminants originated from a common source, namely vehicle emissions. The results demonstrated that the four roads were subject to different degrees of pollution depending on the volume of traffic using each road. Therefore, the results of this study suggest that traffic volume is a major reason for heavy metal pollution.

  5. A research program in determination of heavy metals in sediments and benthic species in relation to nuclear power plant operation

    Science.gov (United States)

    Phelps, H. L.

    1984-01-01

    Heavy metals in the estuarine environment can be toxic to fish and shellfish early life history stages and concentrations build up to levels of concern in marketable shellfish. The present survey was begun just before startup in 1974 of the 1900 megawatt Calvert Cliffs Nuclear Power Plant on the Chesapeake Bay in order to assess and understand factors relating to heavy metal accumulation in estuarine biota. Oysters were collected in large numbers at test and reference sites in June 1974 to 77 and individually analyzed for copper and zinc. Oyster copper and zinc concentrations were correlated with salinity read at time of collection. The relationship of oyster age to metal concentration was examined with two sets of oysters of known age and genetic origin (laboratory spawned). Copper sorption by typical mid Bay sediments, and field studies on cadmium concentrations in sediments were examined.

  6. Two-phase coexistence in the monovalent-to-divalent phase transition of dineopentylbiferrocene-fluorotetracyanoquinodimethane [npBifc-(F1TCNQ)3], charge-transfer salt

    International Nuclear Information System (INIS)

    Uruichi, Mikio; Yue, Yue; Yakushi, Kyuya; Mochida, Tomoyuki

    2007-01-01

    We present experimental findings showing that for npBifc-(F 1 TCNQ) 3 , two phases coexist over a wide temperature interval of 100-150 K near the monovalent-to-divalent phase transition temperature. Macroscopic domains of the high-temperature (monovalent) and low-temperature (divalent) phases were detected in the transition temperature region using X-ray diffraction and micro-Raman spectroscopy techniques. The volume fraction of the two domains continuously varied depending upon the temperature. A considerably large volume difference was found between the monovalent and divalent phases. The effect of volumetric strain due to this volume difference is discussed to understand this inhomogeneous state. (author)

  7. Relation between leaching characteristics of heavy metals and physical properties of fly ashes from typical municipal solid waste incinerators.

    Science.gov (United States)

    Ni, Peng; Li, Hailong; Zhao, Yongchun; Zhang, Junying; Zheng, Chuguang

    2017-09-01

    Due to the alkalinity and high concentration of potentially hazardous heavy metals, fly ash from a municipal solid waste (MSW) incinerator is classified as hazardous waste, which should be of particular concern. Physical and chemical characterizations of the contrasted fly ashes were investigated to explore the relation between leaching characteristics of heavy metals and physical properties of fly ashes. The results showed that CaClOH, NaCl, Ca(OH) 2 , KCl and SiO 2 were primary mineral compositions in the MSWI fly ashes, and the particle size distribution of fly ash ranged between 10 μm and 300 μm. The smaller the particle size distribution of fly ash, the larger the BET-specific surface area, which was beneficial to the leaching of heavy metals. As a result of various pores, it easily accumulated heavy metals as well. The leaching tests exhibited a high leachability of heavy metals and the leaching concentration of Pb in almost all of the fly ash samples went far beyond the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Thereupon, it is necessary to establish proper disposal systems and management strategies for environmental protection based on the characteristics of MSW incineration (MSWI) fly ash in China.

  8. Multi-objective Optimization of Friction Welding Process Parameters using Grey Relational Analysis for Joining Aluminium Metal Matrix Composite

    Directory of Open Access Journals (Sweden)

    Sreenivasan KONGANAPURAM SUNDARARAJAN

    2018-05-01

    Full Text Available Aluminium metal matrix composites has gained importance in recent time because of its improved mechanical and metallurgical properties. The welding of aluminium metal matrix composites using conventional welding process has got many demerits so in order to overcome them a solid state welding process is to be employed. To achieve a good strength weld in the aluminium metal matrix composite bars an efficient and most preferred technique is friction welding. In this work the aluminium metal matrix composite AA7075 + 10 % vol SiC-T6 is selected and friction welded. The combination of friction welding process parameters such as spindle speed, friction pressure, upset pressure and burn-off- length for joining the AA7075 + 10 % vol SiCP-T6 metal matrix composite bars are selected by Taguchi’s design of experiment. The optimum friction welding parameters were determined for achieving improved ultimate tensile strength and the hardness using grey relational analysis. A combined grey relational grade is found from the determined grey relational coefficient of the output responses and the optimum friction welding process parameters were obtained as spindle speed – 1200 rpm, friction pressure – 100 MPa, upset pressure – 250 MPa, Burn-off-Length – 2 mm. Analysis of variance (ANOVA performed shows that the friction pressure is the most significant friction welding parameter that influences the both the ultimate tensile strength and hardness of friction welded AA7075 + 10 % volSiCP-T6 joints. The fractured surface under microstructure study also revealed good compliance with the grey relational grade result. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.17725

  9. Devil's staircase of odd-number charge order modulations in divalent β -vanadium bronzes under pressure

    Science.gov (United States)

    Yamauchi, Touru; Ueda, Hiroaki; Ohwada, Kenji; Nakao, Hironori; Ueda, Yutaka

    2018-03-01

    A common characteristic of quasi-one-dimensional (q1D) conductors β -A0.33V2O5 (A = Li, Na, and Ag) is that the charge ordering (CO), the ground state (GS) at ambient pressure, and the superconducting (SC) phases, the GS under high pressure, are competing with each other. We have explored high-pressure properties of divalent β -vanadium bronzes, β -A0.33V2O5 (A = Ca, Sr, and Pb), which are A -cation stoichiometry finely controlled single-crystal/powder samples, and found the absence of the SC phase. In these observations, however, we observed enormous and novel phase transitions, a kind of "devil's staircase"-type phase transitions in the charge ordering (CO) phases. The most surprising discovery in this devil's staircase, which was found mainly in β -Sr0.33V2O5 , is that all the charge modulation vectors of many kinds of CO phases can be represented as a primitive lattice translation vector along the b axis multiplied by several odd numbers. This discovery surely demonstrates interplay between the charge degree freedom and the crystallographic symmetry. We propose two possible mechanisms to explain this phenomenon: "self-charge transfer (carrier redistribution)" between the two subsystems in these compounds and "sequential symmetry reduction" that was discussed in Landau theory of phase transitions. In β -Ca0.33V2O5 we also found a P -T phase diagram similar in outlook but different in detail. The devil's staircase was also observed but it is an incomplete one. Furthermore, the charge modulation vectors in it are shorter than those in β -Sr0.33V2O5 . In β -Pb0.33V2O5 , which has no CO phase at ambient pressure, the pressure-induced antiferromagnetic ordering was observed at around 50 K above 0.5 GPa. Using these two kinds of mechanisms, we also explain the global high-pressure properties in all the stoichiometric divalent β -vanadium bronzes, which were observed as a wide variety of electromagnetic states. In addition, we also discuss a possible key for

  10. Liquid structure and melting of trivalent metal chlorides

    International Nuclear Information System (INIS)

    Tosi, M.P.; Pastore, G.; Saboungi, M.L.; Price, D.L.

    1991-03-01

    Many divalent and trivalent metal ions in stoichiometric liquid mixtures of their halides with alkali halides are fourfold or sixfold coordinated by halogens into relatively long-lived ''complexes''. The stability of these local coordination states and the connectivity that arises between them in the approach to the pure polyvalent metal halide melt determines the character of its short-range and possible intermediate-range order. The available evidence on local coordination in some 140 mixtures has been successfully classified by a structure sorting method based on Pettifor's chemical scale of the elements. Within the general phenomenological frame provided by structure sorting, main attention is given in this work to the liquid structure and melting mechanisms of trivalent metal chlorides. The liquid structure of YCl 3 is first discussed on the basis of neutron diffraction measurements and of calculations within a simple ionic model, and the melting mechanisms of YCl 3 and AlCl 3 , which are structurally isomorphous in the crystalline state, are contrasted. By appeal to macroscopic melting parameters and transport coefficients and to liquid structure data on SbCl 3 , it is proposed that the melting mechanisms of these salts may be classified into three main types in correlation with the character of the chemical bond. (author). 31 refs, 1 fig., 3 tabs

  11. Metal-induced stress in bivalves living along a gradient of Cd contamination: relating sub-cellular metal distribution to population-level responses

    International Nuclear Information System (INIS)

    Perceval, Olivier; Couillard, Yves; Pinel-Alloul, Bernadette; Giguere, Anik; Campbell, Peter G.C.

    2004-01-01

    The use of biomarkers to assess the impacts of contaminants on aquatic ecosystems has noticeably increased over the past few years. Few of these studies, however, have contributed to the prediction of ecologically significant effects (i.e., at the population or community levels). The present field study was designed to evaluate the potential of metallothionein (MT) and sub-cellular metal partitioning measurements for predicting toxic effects at higher levels of the biological organization in freshwater bivalves (Pyganodon grandis) chronically exposed to Cd. For that purpose, we quantitatively sampled P. grandis populations in the littoral zone of nine lakes on the Precambrian Canadian Shield during two consecutive summers (1998 and 1999); lakes were characterized by contrasting Cd levels but similar trophic status. We tested relationships between the population status of P. grandis (i.e., growth parameters, density, biomass, secondary production, turnover ratio and cumulative fecundity) and (i) ambient Cd concentrations, (ii) sub-organismal responses (MT concentrations in the gill cytosol of individuals and Cd concentrations in three metal-ligand pools identified as M-HMW, the high molecular weight pool, M-MT, the metallothionein-like pool and M-LMW, the low molecular weight pool) and (iii) ecological confounding factors (food resources, presence of host fishes for the obligatory parasitic larval stage of P. grandis). Our results show that littoral density, live weight, dry viscera biomass, production and cumulative fecundity decreased with increasing concentrations of the free-cadmium ion in the environment (Pearson's r ranging from -0.63 to -0.78). On the other hand, theoretical maximum shell lengths (L ∞ ) in our populations were related to both the dissolved Ca concentration and food quality (sestonic C and N concentrations). Overall, Cd concentrations in the gill cytosolic HMW pool of the individual molluscs were the biomarker response that was most

  12. NONLINEAR COLOR-METALLICITY RELATIONS OF GLOBULAR CLUSTERS. III. ON THE DISCREPANCY IN METALLICITY BETWEEN GLOBULAR CLUSTER SYSTEMS AND THEIR PARENT ELLIPTICAL GALAXIES

    International Nuclear Information System (INIS)

    Yoon, Suk-Jin; Lee, Sang-Yoon; Cho, Jaeil; Kim, Hak-Sub; Chung, Chul; Kim, Sooyoung; Lee, Young-Wook; Blakeslee, John P.; Peng, Eric W.; Sohn, Sangmo T.

    2011-01-01

    One of the conundrums in extragalactic astronomy is the discrepancy in observed metallicity distribution functions (MDFs) between the two prime stellar components of early-type galaxies—globular clusters (GCs) and halo field stars. This is generally taken as evidence of highly decoupled evolutionary histories between GC systems and their parent galaxies. Here we show, however, that new developments in linking the observed GC colors to their intrinsic metallicities suggest nonlinear color-to-metallicity conversions, which translate observed color distributions into strongly peaked, unimodal MDFs with broad metal-poor tails. Remarkably, the inferred GC MDFs are similar to the MDFs of resolved field stars in nearby elliptical galaxies and those produced by chemical evolution models of galaxies. The GC MDF shape, characterized by a sharp peak with a metal-poor tail, indicates a virtually continuous chemical enrichment with a relatively short timescale. The characteristic shape emerges across three orders of magnitude in the host galaxy mass, suggesting a universal process of chemical enrichment among various GC systems. Given that GCs are bluer than field stars within the same galaxy, it is plausible that the chemical enrichment processes of GCs ceased somewhat earlier than that of the field stellar population, and if so, GCs preferentially trace the major, vigorous mode of star formation events in galactic formation. We further suggest a possible systematic age difference among GC systems, in that the GC systems in more luminous galaxies are older. This is consistent with the downsizing paradigm whereby stars of brighter galaxies, on average, formed earlier than those of dimmer galaxies; this additionally supports the similar nature shared by GCs and field stars. Although the sample used in this study (the Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel, WFPC2, and WFC3 photometry for the GC systems in the Virgo galaxy cluster) confines our

  13. The MOSDEF Survey: A Stellar Mass–SFR–Metallicity Relation Exists at z ∼ 2.3

    Science.gov (United States)

    Sanders, Ryan L.; Shapley, Alice E.; Kriek, Mariska; Freeman, William R.; Reddy, Naveen A.; Siana, Brian; Coil, Alison L.; Mobasher, Bahram; Davé, Romeel; Shivaei, Irene; Azadi, Mojegan; Price, Sedona H.; Leung, Gene; Fetherholf, Tara; de Groot, Laura; Zick, Tom; Fornasini, Francesca M.; Barro, Guillermo

    2018-05-01

    We investigate the nature of the relation among stellar mass, star formation rate, and gas-phase metallicity (the {M}* –SFR–Z relation) at high redshifts using a sample of 260 star-forming galaxies at z ∼ 2.3 from the MOSDEF survey. We present an analysis of the high-redshift {M}* –SFR–Z relation based on several emission-line ratios for the first time. We show that a {M}* –SFR–Z relation clearly exists at z ∼ 2.3. The strength of this relation is similar to predictions from cosmological hydrodynamical simulations. By performing a direct comparison of stacks of z ∼ 0 and z ∼ 2.3 galaxies, we find that z ∼ 2.3 galaxies have ∼0.1 dex lower metallicity at fixed {M}* and SFR. In the context of chemical evolution models, this evolution of the {M}* –SFR–Z relation suggests an increase with redshift of the mass-loading factor at fixed {M}* , as well as a decrease in the metallicity of infalling gas that is likely due to a lower importance of gas recycling relative to accretion from the intergalactic medium at high redshifts. Performing this analysis simultaneously with multiple metallicity-sensitive line ratios allows us to rule out the evolution in physical conditions (e.g., N/O ratio, ionization parameter, and hardness of the ionizing spectrum) at fixed metallicity as the source of the observed trends with redshift and with SFR at fixed {M}* at z ∼ 2.3. While this study highlights the promise of performing high-order tests of chemical evolution models at high redshifts, detailed quantitative comparisons ultimately await a full understanding of the evolution of metallicity calibrations with redshift. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.

  14. Macrobenthic community in the Douro estuary: relations with trace metals and natural sediment characteristics

    International Nuclear Information System (INIS)

    Mucha, A.P.; Vasconcelos, M.T.S.D.; Bordalo, A.A.

    2003-01-01

    This study used a novel approach to detect a clear signature of metal contamination and biological impacts in an estuary. - The relationship between macrobenthic community structure and natural characteristics of sediment and trace metal contamination were studied in the lower Douro estuary (Portugal, NW, Iberian Peninsula), using an innovative threefold approach (SQG, Sediment Quality Guidelines), metal normalization to Fe, and macrobenthic community structure. This study allowed detection of a clear signature of anthropogenic contamination, in terms of Zn, Cu, Pb, and Cr in the north bank of the estuary, which experiences high urban pressure. Using the SQG approach, metal concentrations above ERM (effects range--median) were observed only at one sampling station, but several stations had levels above ERL (effects range-low). The macrobenthic community had a low diversity, with only 19 species found in the entire estuarine area, dominated by opportunistic species. The granulometric distribution of the sediments (estimated from the combination of organic matter, Fe and Al) seemed to be the major structuring factor for the communities, establishing the natural macrobenthic distribution pattern. The metals (Zn, Cu, Pb, and Cr) seemed to act as a disturbing factor over the natural distribution, with deleterious consequences for the macrobenthic communities

  15. Mercury vacancies as divalent acceptors in Hg{sub y}Te{sub 1} {sub –} {sub y}/Cd{sub x}Hg{sub 1} {sub –} {sub x}Te structures with quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Kozlov, D. V., E-mail: dvkoz@ipmras.ru; Rumyantsev, V. V.; Morozov, S. V.; Kadykov, A. M.; Fadeev, M. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Varavin, V. S.; Mikhailov, N. N.; Dvoretsky, S. A. [Russian Academy of Sciences, Rzhanov Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Gavrilenko, V. I. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Teppe, F. [Laboratoire Charles Coulomb (L2C) (France)

    2016-12-15

    A long-wavelength band caused by transitions between states related to the valence band is detected in the photoconductivity spectra of Hg{sub y}Te{sub 1–y}/Cd{sub x}Hg{sub 1–x}Te (CMT) structures with quantum wells. The energy states of mercury vacancies in quantum wells of CMT structures is calculated taking into account a chemical shift. It is shown that the long-wavelength band observed in the photoconductivity spectra of these structures is associated with the ionization of divalent acceptor centers which are such vacancies.

  16. High pressure metallization of Mott Insulators: Magnetic, structural and electronic properties

    International Nuclear Information System (INIS)

    Pasternak, M.P.; Hearne, G.; Sterer, E.; Taylor, R.D.; Jeanloz, R.

    1993-01-01

    High pressure studies of the insulator-metal transition in the (TM)I 2 (TM = V, Fe, Co and Ni) compounds are described. Those divalent transition-metal iodides are structurally isomorphous and classified as Mott Insulators. Resistivity, X-ray diffraction and Moessbauer Spectroscopy were employed to investigate the electronic, structural, and magnetic properties as a function of pressure both on the highly correlated and on the metallic regimes

  17. Improvements in or relating to the production of metal-containing material in particulate form

    International Nuclear Information System (INIS)

    Woodhead, J.L.; Scott, K.T.B.; Ball, P.W.

    1977-01-01

    The process described refers mainly to production of the material in the form of very small spheres. It comprises forming a metal compound-containing gel precipitate by mixing a solution or sol of the metal compound with a soluble organic polymer and contacting the mixture with a precipitating reagent to precipitate the metal as an insoluble compound bound with the polymer. The precipitate is then subjected in the liquid phase to a breaking down and dispersing process to produce an intermediate product suitable for spray drying, and the intermediate product is spray dried to form the particulate product. The breaking down and dispersing process may be performed by means of a colloid mill or vibratory stirrer. Examples of application of the process are described. (U.K.)

  18. Heavy metals uptake by sonicated activated sludge: Relation with floc surface properties

    International Nuclear Information System (INIS)

    Laurent, Julien; Casellas, Magali; Dagot, Christophe

    2009-01-01

    The effects of sonication of activated sludge on heavy metal uptake were in a first time investigated in respect with potential modifications of floc surface properties. The treatment led to the simultaneous increase of specific surface area and of the availability of negative and/or hydrophilic sites. In parallel, organic matter was released in the soluble fraction. Sorption isotherms of cadmium and copper showed that uptake characteristics and mechanisms were highly dependent on both heavy metal species and specific energy supplied. The increase of both specific surface area and fixation sites availability led to the increase of Cd(II) uptake. For Cu(II), organic matter released in soluble phase during the treatment seemed to act as a ligand and to limit adsorption on flocs surface. Three different heavy metals uptake mechanisms have been identified: proton exchange, ion exchange and (co)precipitation

  19. The galaxy population of Abell 1367: the stellar mass-metallicity relation

    Science.gov (United States)

    Mouhcine, M.; Kriwattanawong, W.; James, P. A.

    2011-04-01

    Using wide baseline broad-band photometry, we analyse the stellar population properties of a sample of 72 galaxies, spanning a wide range of stellar masses and morphological types, in the nearby spiral-rich and dynamically young galaxy cluster Abell 1367. The sample galaxies are distributed from the cluster centre out to approximately half the cluster Abell radius. The optical/near-infrared colours are compared with simple stellar population synthesis models from which the luminosity-weighted stellar population ages and metallicities are determined. The locus of the colours of elliptical galaxies traces a sequence of varying metallicity at a narrow range of luminosity-weighted stellar ages. Lenticular galaxies in the red sequence, however, exhibit a substantial spread of luminosity-weighted stellar metallicities and ages. For red-sequence lenticular galaxies and blue cloud galaxies, low-mass galaxies tend to be on average dominated by stellar populations of younger luminosity-weighted ages. Sample galaxies exhibit a strong correlation between integrated stellar mass and luminosity-weighted stellar metallicity. Galaxies with signs of morphological disturbance and ongoing star formation activity, tend to be underabundant with respect to passive galaxies in the red sequence of comparable stellar masses. We argue that this could be due to tidally driven gas flows towards the star-forming regions, carrying less enriched gas and diluting the pre-existing gas to produce younger stellar populations with lower metallicities than would be obtained prior to the interaction. Finally, we find no statistically significant evidence for changes in the luminosity-weighted ages and metallicities for either red-sequence or blue-cloud galaxies, at fixed stellar mass, with location within the cluster. We dedicate this work to the memory of our friend and colleague C. Moss who died suddenly recently.

  20. Age-Related Uptake of Heavy Metals in Human Spinal Interneurons.

    Directory of Open Access Journals (Sweden)

    Roger Pamphlett

    Full Text Available Toxic heavy metals have been implicated in the loss of spinal motoneurons in amyotrophic lateral sclerosis/motor neuron disease (ALS/MND. Motoneuron loss in the spinal anterior horn is severe in ALS/MND at the time of death, making this tissue unsuitable for examination. We therefore examined spinal cords of people without muscle weakness to look for any presence of heavy metals that could make these neurons susceptible to damage. Spinal cord samples from 50 individuals aged 1-95 y who had no clinical or histopathological evidence of spinal motoneuron loss were studied. Seven μm formalin-fixed paraffin-embedded sections were stained for heavy metals with silver nitrate autometallography (AMGHM which detects intracellular mercury, silver or bismuth. Neurons in the spinal cord were classified as interneurons or α-motoneurons based on their site and cell body diameter. Spinal interneurons containing heavy metals were present in 8 of 24 people (33% aged 61-95 y, but not at younger ages. These AMGHM interneurons were most numerous in the lumbar spinal cord, with moderate numbers in the caudal cervical cord, few in the rostral cervical cord, and almost none in the thoracic cord. All people with AMGHM interneurons had occasional AMGHM staining in α-motoneurons as well. In one man AMGHM staining was present in addition in dorsomedial nucleus and sensory neurons. In conclusion, heavy metals are present in many spinal interneurons, and in a few α-motoneurons, in a large proportion of older people. Damage to inhibitory interneurons from toxic metals in later life could result in excitotoxic injury to motoneurons and may underlie motoneuron injury or loss in conditions such as ALS/MND, multiple sclerosis, sarcopenia and calf fasciculations.

  1. Metal recycling technology and related issues in the United States, a BNFL perspective

    International Nuclear Information System (INIS)

    Bradbury, P.; Dam, S.; Starke, W.

    1995-01-01

    Radioactively contaminated metallic materials comprise a large part of the potential waste products which result from nuclear facility repair, refurbishment, and decommissioning. United States Government (Departments of Energy and Defense) facilities, U.S. nuclear power plants, and other commercial nuclear fuel cycle facilities have large inventories of radioactive scrap metal which could be decontaminated and recycled into useful radioactive and non-radioactive products. Residual radioactivity and recycling criteria is needed to avoid the high cost of disposal and the waste of natural resources. In the United Kingdom, BNFL has decommissioned the gaseous diffusion plant at Capenhurst and has recycled a large fraction of the metallic scrap into the metals market. Other structural materials have also been released as uncontaminated scrap. U.K. release criteria for residual radionuclide contamination have been applied to these operations. A variety of techniques were utilized to size reduce large components, to remove radioactivity, and to survey and release these materials. These methods and the application of release criteria has a direct relationship to methods which would be applicable in the U.S. and in other countries. This paper will describe the specific U.K. technology and experience in the decontamination, recycle, and release of scrap metal. It will also describe the U.S. environment for metal recycle, including the volumes and levels of contamination, and the current and proposed release criteria. Comparisons will be presented between the U.S. and U.K., both in technology and methodology for recycle and in regulatory criteria for residual radioactivity and material release and for ultimate decommissioning. The paper will then provide suggested approaches and criteria for U.S. recycling and decommissioning. (author)

  2. INTERTEXTUAL RELATIONS IN METAL FIRTINA 4 TURAN NOVEL METAL FIRTINA 4 TURAN ROMANINDA METİNLERARASI İLİŞKİLER

    Directory of Open Access Journals (Sweden)

    Mehmet SOĞUKÖMEROĞULLARI

    2012-06-01

    Full Text Available Tradition is employed in the course of progress of genre of novel, which is introduced to Turkish literature through translations from Western Literature. Especially, the way that Ahmet Mithat Efendi followed provides basis fort he progress of the novel of that kind. In modern thought, corresponding sense of that way is intertextual relations. Briefly, intertextual relations that refer to the gathering and the fashion of redesigning of other texts echo in Metal Fırtına 4 Turan, the subject matter of this study. Metal Fırtına 4 Turan consists of the gathering and reinterpretation of such elements of especially folklore, mythology, and folk literature as Shamanism, Ergenekon epic, wolf, and end of the world or Kalgançı Çak legend. Those elements in the novel constitute the subject matter of this article. Türk edebiyatına Batı edebiyatından çevirilerle giren roman türünün gelişim aşamasında gelenekten faydalanılır. Özellikle Ahmet Mithat Efendi’nin izlediği yol bu yönde romanın ilerlemesine zemin hazırlar. Bu tarzın modern düşüncede karşılığı metinlerarası ilişkilerdir. Kısaca, bir metnin başka metinlerin bir araya gelmesi ve yeniden tasarlanması şeklinde tanımlanabilecek olan metinlerarası ilişkiler, inceleme konumuz olan Metal Fırtına 4 Turan romanına da yansır. Özellikle folklor, mitoloji veya halk edebiyatı ögelerinden Şamanizm, Ergenekon destanı, kurt ve dünyanın sonu veya Kalgançı Çak efsanesinin bir araya getirilerek yeniden yorumlanmasıyla oluşan Metal Fırtına 4 Turan romanındaki bu unsurlar makalenin konusunu teşkil eder.

  3. Monitoring of heavy metals in selected Water Supply Systems in Poland, in relation to current regulations

    Science.gov (United States)

    Szuster-Janiaczyk, Agnieszka; Zeuschner, Piotr; Noga, Paweł; Skrzypczak, Marta

    2018-02-01

    The study presents an analysis of water quality monitoring in terms of the content of heavy metals, which is conducted in three independent water supply systems in Poland. The analysis showed that the monitoring of heavy metals isn't reliable - both the quantity of tested water samples and the location of the monitoring points are the problem. The analysis of changes in water quality from raw water to tap water was possible only for one of the analysed systems and indicate a gradual deterioration of water quality, although still within acceptable limits of legal regulations.

  4. Synthesized cellulose/succinic anhydride as an ion exchanger. Calorimetry of divalent cations in aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Julio C.P. [Institute of Chemistry, University of Campinas, UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP (Brazil); Silva Filho, Edson C. [LIMAV, Federal University of Piaui, 64049-550 Teresina, Piaui (Brazil); Santana, Sirlane A.A. [Departamento de Quimica/CCET, Universidade Federal do Maranhao, Av. dos Portugueses S/N, Campus do Bacanga, 65080-540 Sao Luiz, MA (Brazil); Airoldi, Claudio, E-mail: airoldi@iqm.unicamp.br [Institute of Chemistry, University of Campinas, UNICAMP, P.O. Box 6154, 13084-971 Campinas, SP (Brazil)

    2011-09-20

    Highlights: {yields} Synthetic route based on anhydride melting point. {yields} Cellulosic biopolymer/anhydride as ion exchanger. {yields} Calorimetry of cation exchange at solid/liquid interface. {yields} Favorable thermodynamic data of exchanging process. - Abstract: A synthetic route to a biopolymer/anhydride ion exchanger adds cellulose directly to molten succinic anhydride in a quasi solvent-free procedure. An amount of 3.07 {+-} 0.05 mmol of pendant groups incorporated onto the polymeric structure, which was characterized by elemental analysis, solid state carbon NMR, infrared, X-ray and thermogravimetry. The new polysaccharide is able to exchange cations from aqueous solution through a batchwise methodology, to obtain 2.46 {+-} 0.09 mmol g{sup -1} for divalent cobalt and nickel cations. The net thermal effects obtained from calorimetric titrations gave endothermic values of 3.81 {+-} 0.02 and 2.35 {+-} 0.01 kJ mol{sup -1}. The spontaneity of this ion-exchange process reflected in negative Gibbs energies and also a positive entropic contribution. These thermodynamic data at the solid/liquid interface suggests a favorable ion exchange process for this anchored biopolymer, for cation removal from the environment.

  5. Immobilization of ethylenesulfide on babassu coconut epicarp and mesocarp for divalent cation sorption

    International Nuclear Information System (INIS)

    Santana, Sirlane A.A.; Vieira, Adriana P.; Silva Filho, Edson C. da; Melo, Julio C.P.; Airoldi, Claudio

    2010-01-01

    A new synthetic methodology route consisted in reacting the natural babassu coconut mesocarp (BCM) and babassu coconut epicarp (BCE) with ethylenesufide, for adding basic sulfur centers in pendant chains that possess high potential activity for coordinating divalent cations from aqueous solution. All biomaterials were characterized by elemental analysis, infrared (IR), 13 C NMR and thermogravimetry. The sulfur elemental analysis gave 2.00 ± 0.05 and 8.67 ± 0.01% for BCES and BCMS, which correspond to 0.60 ± 0.01 and 2.71 ± 0.01 mmol of this element per each gram of BCE and BCM, to confer a degree of functionalization of 20.2 ± 0.07 and 86.7 ± 0.01 mg g -1 . This synthesis enabled from IR weak SH band at 2544 cm -1 due to the incorporation of the reagent into the structure. The basic centers favor copper sorption with increasing pH from 2 to 6 observed by a batchwise methodology and the data obtained from the chosen pH 6 were adjusted to Freundlich and Langmuir models, favoring fit for the latter equation. The kinetics of sorption was established at 30 min for both biopolymers with a pseudo-second-order model.

  6. Probing Induced Structural Changes in Biomimetic Bacterial Cell Membrane Interactions with Divalent Cations

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Allison M [ORNL; Standaert, Robert F [ORNL; Jubb, Aaron M [ORNL; Katsaras, John [ORNL; Johs, Alexander [ORNL

    2017-01-01

    Biological membranes, formed primarily by the self-assembly of complex mixtures of phospholipids, provide a structured scaffold for compartmentalization and structural processes in living cells. The specific physical properties of phospholipid species present in a given membrane play a key role in mediating these processes. Phosphatidylethanolamine (PE), a zwitterionic lipid present in bacterial, yeast, and mammalian cell membranes, is exceptional. In addition to undergoing the standard lipid polymorphic transition between the gel and liquid-crystalline phase, it can also assume an unusual polymorphic state, the inverse hexagonal phase (HII). Divalent cations are among the factors that drive the formation of the HII phase, wherein the lipid molecules form stacked tubular structures by burying the hydrophilic head groups and exposing the hydrophobic tails to the bulk solvent. Most biological membranes contain a lipid species capable of forming the HII state suggesting that such lipid polymorphic structural states play an important role in structural biological processes such as membrane fusion. In this study, the interactions between Mg2+ and biomimetic bacterial cell membranes composed of PE and phosphatidylglycerol (PG) were probed using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), and fluorescence spectroscopy. The lipid phase transitions were examined at varying ratios of PE to PG and upon exposure to physiologically relevant concentrations of Mg2+. An understanding of these basic interactions enhances our understanding of membrane dynamics and how membrane-mediated structural changes may occur in vivo.

  7. Opposing effects of cationic antimicrobial peptides and divalent cations on bacterial lipopolysaccharides

    Science.gov (United States)

    Smart, Matthew; Rajagopal, Aruna; Liu, Wing-Ki; Ha, Bae-Yeun

    2017-10-01

    The permeability of the bacterial outer membrane, enclosing Gram-negative bacteria, depends on the interactions of the outer, lipopolysaccharide (LPS) layer, with surrounding ions and molecules. We present a coarse-grained model for describing how cationic amphiphilic molecules (e.g., antimicrobial peptides) interact with and perturb the LPS layer in a biologically relevant medium, containing monovalent and divalent salt ions (e.g., Mg2+). In our approach, peptide binding is driven by electrostatic and hydrophobic interactions and is assumed to expand the LPS layer, eventually priming it for disruption. Our results suggest that in parameter ranges of biological relevance (e.g., at micromolar concentrations) the antimicrobial peptide magainin 2 effectively disrupts the LPS layer, even though it has to compete with Mg2+ for the layer. They also show how the integrity of LPS is restored with an increasing concentration of Mg2+. Using the approach, we make a number of predictions relevant for optimizing peptide parameters against Gram-negative bacteria and for understanding bacterial strategies to develop resistance against cationic peptides.

  8. Interaction of divalent cations with basal planes and edge surfaces of phyllosilicate minerals: muscovite and talc.

    Science.gov (United States)

    Yan, Lujie; Masliyah, Jacob H; Xu, Zhenghe

    2013-08-15

    Smooth basal plane and edge surfaces of two platy phyllosilicate minerals (muscovite and talc) were prepared successfully to allow accurate colloidal force measurement using an atomic force microscope (AFM), which allowed us to probe independently interactions of divalent cations with phyllosilicate basal planes and edge surfaces. The Stern potential of basal planes and edge surfaces was obtained by fitting the measured force profiles with the classical DLVO theory. The fitted Stern potential of the muscovite basal plane became less negative with increasing Ca(2+) or Mg(2+) concentration but did not reverse its sign even at Ca(2+) or Mg(2+) concentrations up to 5 mM. In contrast, the Stern potential of the muscovite edge surface reversed at Ca(2+) or Mg(2+) concentrations as low as 0.1 mM. The Stern potential of the talc basal plane became less negative with 0.1 mM Ca(2+) addition and nearly zero with 1 mM Ca(2+) addition. The Stern potential of talc edge surface became reversed with 0.1 mM Ca(2+) or 1 mM Mg(2+) addition, showing not only a different binding mechanism of talc basal planes and edge surfaces with Ca(2+) and Mg(2+), but also different binding mechanism between Ca(2+) and Mg(2+) ions with basal planes and edge surfaces. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. A Review of Flood-Related Storage and Remobilization of Heavy Metal Pollutants in River Systems

    Czech Academy of Sciences Publication Activity Database

    Ciszewski, D.; Matys Grygar, Tomáš

    2016-01-01

    Roč. 227, č. 7 (2016), s. 227-239 ISSN 0049-6979 R&D Projects: GA ČR(CZ) GA15-00340S Institutional support: RVO:61388980 Keywords : River * Sediment * Heavy metals * Mobilization * Pollution Subject RIV: DD - Geochemistry Impact factor: 1.702, year: 2016

  10. Transition-metal derivatives of nido-boranes and some related species

    International Nuclear Information System (INIS)

    Greenwood, N.N.; Kennedy, J.D.

    1982-01-01

    This paper reviews the wide variety of metalloboranes that have been made by the reactions of transitional-metal compounds with nido-boranes or their anions. The authors concentrate on preparative and structural aspects and discuss presumed reaction mechanisms or postulated modes of bonding. Monoboron, diboron, triboron, tetraboron, pentaboron, hexaboron, nonaboron, decaboron, octadecaboron, and icosaboron compounds are discussed

  11. Assessment of heavy metal pollution in Ghana by nuclear-related techniques

    International Nuclear Information System (INIS)

    Akoto Bamford, S.; Aboh, I.; Osae, E.

    1992-01-01

    X-ray fluorescence analysis and atomic absorption spectrophotometry was used to test for the presence and levels of heavy metals in solid wastes discharged from the gold mining industry. This report contains the results of the analysis of vegetation and river sediment samples. 2 refs, 2 tabs

  12. Binary and ternary carbides and nitrides of the transition metals and their phase relations

    International Nuclear Information System (INIS)

    Holleck, H.

    1981-01-01

    The occurrance and the structure of the binary and ternary transition metal carbides and nitrides are described. Phase diagrams are assessed for most of the binary and ternary systems. Many ternary phase diagrams are published in this report for the first time. (orig.) [de

  13. Salinity-Dependent Contact Angle Alteration in Oil/Brine/Silicate Systems: the Critical Role of Divalent Cations.

    Science.gov (United States)

    Haagh, M E J; Siretanu, I; Duits, M H G; Mugele, F

    2017-04-11

    The effectiveness of water flooding oil recovery depends to an important extent on the competitive wetting of oil and water on the solid rock matrix. Here, we use macroscopic contact angle goniometry in highly idealized model systems to evaluate how brine salinity affects the balance of wetting forces and to infer the microscopic origin of the resultant contact angle alteration. We focus, in particular, on two competing mechanisms debated in the literature, namely, double-layer expansion and divalent cation bridging. Our experiments involve aqueous droplets with a variable content of chloride salts of Na + , K + , Ca 2+ , and Mg 2+ , wetting surfaces of muscovite and amorphous silica, and an environment of ambient decane containing small amounts of fatty acids to represent polar oil components. By diluting the salt content in various manners, we demonstrate that the water contact angle on muscovite, not on silica, decreases by up to 25° as the divalent cation concentration is reduced from typical concentrations in seawater to zero. Decreasing the ionic strength at a constant divalent ion concentration, however, has a negligible effect on the contact angle. We discuss the consequences for the interpretation of core flooding experiments and the identification of a microscopic mechanism of low salinity water flooding, an increasingly popular, inexpensive, and environment-friendly technique for enhanced oil recovery.

  14. The relative influence of metal ion binding sites in the I-like domain and the interface with the hybrid domain on rolling and firm adhesion by integrin alpha4beta7.

    Science.gov (United States)

    Chen, JianFeng; Takagi, Junichi; Xie, Can; Xiao, Tsan; Luo, Bing-Hao; Springer, Timothy A

    2004-12-31

    We examined the effect of conformational change at the beta(7) I-like/hybrid domain interface on regulating the transition between rolling and firm adhesion by integrin alpha(4)beta(7). An N-glycosylation site was introduced into the I-like/hybrid domain interface to act as a wedge and to stabilize the open conformation of this interface and hence the open conformation of the alpha(4) beta(7) headpiece. Wild-type alpha(4)beta(7) mediates rolling adhesion in Ca(2+) and Ca(2+)/Mg(2+) but firm adhesion in Mg(2+) and Mn(2+). Stabilizing the open headpiece resulted in firm adhesion in all divalent cations. The interaction between metal binding sites in the I-like domain and the interface with the hybrid domain was examined in double mutants. Changes at these two sites can either counterbalance one another or be additive, emphasizing mutuality and the importance of multiple interfaces in integrin regulation. A double mutant with counterbalancing deactivating ligand-induced metal ion binding site (LIMBS) and activating wedge mutations could still be activated by Mn(2+), confirming the importance of the adjacent to metal ion-dependent adhesion site (ADMIDAS) in integrin activation by Mn(2+). Overall, the results demonstrate the importance of headpiece allostery in the conversion of rolling to firm adhesion.

  15. The Relative Influence of Metal Ion Binding Sites in the I-like Domain and the Interface with the Hybrid Domain on Rolling and Firm Adhesion by Integrin α4β7*

    Science.gov (United States)

    Chen, JianFeng; Takagi, Junichi; Xie, Can; Xiao, Tsan; Luo, Bing-Hao; Springer, Timothy A.

    2015-01-01

    We examined the effect of conformational change at the β7 I-like/hybrid domain interface on regulating the transition between rolling and firm adhesion by integrin α4β7. An N-glycosylation site was introduced into the I-like/hybrid domain interface to act as a wedge and to stabilize the open conformation of this interface and hence the open conformation of the α4β7 headpiece. Wild-type α4β7 mediates rolling adhesion in Ca2+ and Ca2+/Mg2+ but firm adhesion in Mg2+ and Mn2+. Stabilizing the open headpiece resulted in firm adhesion in all divalent cations. The interaction between metal binding sites in the I-like domain and the interface with the hybrid domain was examined in double mutants. Changes at these two sites can either counterbalance one another or be additive, emphasizing mutuality and the importance of multiple interfaces in integrin regulation. A double mutant with counterbalancing deactivating ligand-induced metal ion binding site (LIMBS) and activating wedge mutations could still be activated by Mn2+, confirming the importance of the adjacent to metal ion-dependent adhesion site (ADMIDAS) in integrin activation by Mn2+. Overall, the results demonstrate the importance of headpiece allostery in the conversion of rolling to firm adhesion. PMID:15448154

  16. Data in support of the negative influence of divalent cations on (?)-epigallocatechin-3-gallate (EGCG)-mediated inhibition of matrix metalloproteinase-2 (MMP-2)

    OpenAIRE

    Deb, Gauri; Batra, Sahil; Limaye, Anil M.

    2015-01-01

    In this data article we have provided evidence for the negative influence of divalent cations on (−)‐epigallocatechin-3-gallate (EGCG)-mediated inhibition of matrix metalloproteinase-2 (MMP-2) activity in cell-free experiments. Chelating agents, such as EDTA and sodium citrate alone, did not affect MMP-2 activity. While EDTA enhanced, excess of divalent cations interfered with EGCG-mediated inhibition of MMP-2.

  17. The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries

    OpenAIRE

    Rebassa-Mansergas, A.; Anguiano, B.; García-Berro, E.; Freeman, K. C.; Cojocaru, R.; Manser, C. J.; Pala, A. F.; Gänsicke, B. T.; Liu, X. -W.

    2016-01-01

    The age–metallicity relation (AMR) is a fundamental observational constraint for understanding how the Galactic disc formed and evolved chemically in time. However, there is not yet an agreement on the observational properties of the AMR for the solar neighbourhood, primarily due to the difficulty in obtaining accurate stellar ages for individual field stars. We have started an observational campaign for providing the much needed observational input by using wide white-dwarf–main-sequence (WD...

  18. Metal distributions in complexes with Chlorella vulgaris in seawater and wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, P.R.; Kowalak, A.D.

    1999-10-01

    Divalent cadmium (Cd), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) simultaneous complexes with an algal biomass Chlorella vulgaris were studied for bioremediation purposes in various aqueous media: distilled-deionized water (DDIW), seawater, nuclear-reactor pool water, and process wastewater. Reactions were monitored using various dry masses of algae at constant temperature and constant metal concentrations for reaction times ranging from 0 to 150 minutes. Complexes occurred within 30 minutes and reached a steady state after 80 to 120 minutes. Distribution constants (K{prime}{sub d}) were calculated for the complexes and relative orders of K{prime}{sub d} were reported. The K{prime}{sub d} are used to evaluate relative efficiency of metal remediation from waters. Lead, Cu, and Ni complexes had the greatest K{prime}{sub d} values and those metals were most efficiently removed from these waters. Zinc and Fe formed the most labile complexes. The order of K{prime}{sub d} values for complexes in DDIW was Pb > Cu > Cd > Zn, then Cu > Cd > Zn in seawater, Cd > Cu > Zn in reactor pool water, and Ni > Cd > Cu > Zn > Fe in wastewater. C. vulgaris biomass may potentially be used as an alternative to traditional water treatment methods for simultaneous extraction of metals from seawater, process wastewater, or drinking water.

  19. Translocation of metal phosphate via the phosphate inorganic transport system of Escherichia coli

    NARCIS (Netherlands)

    van Veen, H.W; Abee, T.; Kortstee, G.J J; Konings, W.N; Zehnder, A.J B

    1994-01-01

    P-i transport via the phosphate inorganic transport system (Pit) of Escherichia coil was studied in natural and artificial membranes. P-i uptake via Pit is dependent on the presence of divalent cations, like Mg2+, Ca2+, Co2+, or Mn2+, which form a soluble, neutral metal phosphate (MeHPO(4)) complex.

  20. A randomized, controlled intervention of machine guarding and related safety programs in small metal-fabrication businesses.

    Science.gov (United States)

    Parker, David L; Brosseau, Lisa M; Samant, Yogindra; Xi, Min; Pan, Wei; Haugan, David

    2009-01-01

    Metal fabrication employs an estimated 3.1 million workers in the United States. The absence of machine guarding and related programs such as lockout/tagout may result in serious injury or death. The purpose of this study was to improve machine-related safety in small metal-fabrication businesses. We used a randomized trial with two groups: management only and management-employee. We evaluated businesses for the adequacy of machine guarding (machine scorecard) and related safety programs (safety audit). We provided all businesses with a report outlining deficiencies and prioritizing their remediation. In addition, the management-employee group received four one-hour interactive training sessions from a peer educator. We evaluated 40 metal-fabrication businesses at baseline and 37 (93%) one year later. Of the three nonparticipants, two had gone out of business. More than 40% of devices required for adequate guarding were missing or inadequate, and 35% of required safety programs and practices were absent at baseline. Both measures improved significantly during the course of the intervention. No significant differences in changes occurred between the two intervention groups. Machine-guarding practices and programs improved by up to 13% and safety audit scores by up to 23%. Businesses that added safety committees or those that started with the lowest baseline measures showed the greatest improvements. Simple and easy-to-use assessment tools allowed businesses to significantly improve their safety practices, and safety committees facilitated this process.

  1. On the valence state of Yb and Ce in transition metal intermetallic compounds

    International Nuclear Information System (INIS)

    Boer, F.R. de; Dijkman, W.H.; Mattens, W.C.M.

    1979-01-01

    In the pure state Yb is a divalent metal, similar to Ca; in alloys it can become trivalent like the majority of the rare earth metals. Using a value of 38 kJ (mol Yb) -1 for the energy difference between divalent and trivalent Yb metal and using model calculations for the heat of formation of intermetallic compounds, the authors are able to account for the existing information on the valence state of Yb in transition metal compounds. A similar analysis of compounds of Ce with transition metals shows that a model in which the 4f electron is treated as a core electron, i.e. being absent in the tetravalent modification of Ce and present as a fully localized electron in trivalent Ce, does not apply. (Auth.)

  2. Assessment of levels and 'health-effects' of airborne particulate matter in mining, metal refining and metal working industries using nuclear and related analytical techniques

    International Nuclear Information System (INIS)

    2008-01-01

    The International Atomic Energy Agency (IAEA) has been supporting, over the years, several coordinated research programmes (CRPs) on various research topics related to environmental issues impacting human health. The primary aim of these CRPs has been to help enhance the research and development capabilities in the Member States, particularly among developing countries; to identify the sources of various environmental contaminants and evaluate their fate; and to provide for the basis of improved health among human populations by the use of nuclear and related analytical techniques. The CRP on Assessment of Levels and Health-Effects of Airborne Particulate Matter in Mining, Metal Refining and Metal Working Industries using nuclear and related analytical techniques focused on improving the competence for research on workplace monitoring in a variety of industrial environments. The personal monitoring of the APM (airborne particulate matter) of the exposed workforce was carried out for the first time by many participants. Nuclear and related analytical techniques, including the application of proton micro-beam, were used to generate the trace element concentration profiles in various biomarkers tissues of the exposed workers. The quality assurance/quality control (QA/QC) aspects related to the CRP were addressed through intercomparison analyses of APM on filter paper samples and freeze dried human urine samples to generate validated data. These data have helped to generate correlations between the occupational exposure measured and the magnitude of the biological response. Such new information is essential to evolve procedures to considerably reduce/eliminate the pollutants in the workplace environment and to make informed decisions on the evolution of standards in working environments aimed at preserving the health of workers. The purpose of this TECDOC is to provide an overview of the activities performed under the CRP by the participants. The overall achievements

  3. Related Structure Characters and Stability of Structural Defects in a Metallic Glass.

    Science.gov (United States)

    Niu, Xiaofeng; Feng, Shidong; Pan, Shaopeng

    2018-03-22

    Structural defects were investigated by a recently proposed structural parameter, quasi-nearest atom (QNA), in a modeled Zr 50 Cu 50 metallic glass through molecular dynamics simulations. More QNAs around an atom usually means that more defects are located near the atom. Structural analysis reveals that the spatial distribution of the numbers of QNAs displays to be clearly heterogeneous. Furthermore, QNA is closely correlated with cluster connections, especially four-atom cluster connections. Atoms with larger coordination numbers usually have less QNAs. When two atoms have the same coordination number, the atom with larger five-fold symmetry has less QNAs. The number of QNAs around an atom changes rather frequently and the change of QNAs might be correlated with the fast relaxation metallic glasses.

  4. A study on the treatment process of industrial wastewater related to heavy metal wastewater

    International Nuclear Information System (INIS)

    Park, J. J.; Shin, J. M.; Kim, J. H.; Yang, M. S.; Kim, M. J.; Son, J. S.; Park, H. S.

    1999-08-01

    The supernatant from metal wastewater by using magnesium hydroxide and dolomite was used to treat dyeing wastewater. In the case of magnesium hydroxide. In the case of magnesium hydroxide, the optimum dosage was 10 % (v/v) for supernatant A and 3 % (v/v) for separation B. Color turbidity and COD removal was 99 to 100 % , 85 to 97 % and 43 to 53 %, respectively. In the case of dolomite, the optimum dosage was 30 % (v/v) for supernatant A and 3% for supernatant B. Color, turbidity and COD removal was 96 to 99 %, 62 to 91 % and 52 to 53 %, respectively. In dyeing wastewater treatment by using supernatant from metal wastewater, the cost of chemicals was reduced by about 80 %

  5. Related Structure Characters and Stability of Structural Defects in a Metallic Glass

    Science.gov (United States)

    Niu, Xiaofeng; Feng, Shidong; Pan, Shaopeng

    2018-01-01

    Structural defects were investigated by a recently proposed structural parameter, quasi-nearest atom (QNA), in a modeled Zr50Cu50 metallic glass through molecular dynamics simulations. More QNAs around an atom usually means that more defects are located near the atom. Structural analysis reveals that the spatial distribution of the numbers of QNAs displays to be clearly heterogeneous. Furthermore, QNA is closely correlated with cluster connections, especially four-atom cluster connections. Atoms with larger coordination numbers usually have less QNAs. When two atoms have the same coordination number, the atom with larger five-fold symmetry has less QNAs. The number of QNAs around an atom changes rather frequently and the change of QNAs might be correlated with the fast relaxation metallic glasses. PMID:29565298

  6. Multicharged ion-induced emission from metal- and insulator surfaces related to magnetic fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Winter, H.P. [Technische Univ., Vienna (Austria). Inst. fuer Allgemeine Physik

    1997-01-01

    The edge region of magnetically confined plasmas in thermonuclear fusion experiments couples the hot plasma core with the cold first wall. We consider the dependence of plasma-wall interaction processes on edge plasma properties, with particular emphasis on the role of slow multicharged ions (MCI). After a short survey on the physics of slow MCI-surface interaction we discuss recent extensive studies on MCI-induced electron emission from clean metal surfaces conducted at impact velocities << 1 a.u., from which generally reliable total electron yields can be obtained. We then demonstrate the essentially different role of the MCI charge for electron emission from metallic and insulator surfaces, respectively. Furthermore, we present recent results on slow MCI-induced `potential sputtering` of insulators which, in contrast to the well established kinetic sputtering, already occurs at very low ion impact energy and strongly increases with the MCI charge state. (J.P.N.). 55 refs.

  7. Relation between the degree of lung pollution by air pollution and heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, H; Endo, R; Takemoto, K

    1975-04-01

    Human and dog lungs were analyzed for 13 kinds of heavy metals. The human lungs (all of Tokyo citizens) showed a broad range of dust sedimentation, some correlation between the degree of pollution and the amount of cadmium, nickel, and chromium only, and conspicuous individual differences seemingly due to occupation. No correlation was found between the amount of pulmonary metals, and age, or sex. In dog lungs there was no correlation between the local pollution and the amount of iron, copper, zinc, cobalt, and cadmium. Cadmium, nickel, lead, and chromium showed a correlation between local air pollution in human lungs. In dogs obtained in Korea, Ni and Cr were higher than in dog lungs obtained in Jinsen.

  8. Methane oxidation over noble metal catalysts as related to controlling natural gas vehicle exhaust emissions

    International Nuclear Information System (INIS)

    Oh, S.H.; Mitchell, P.J.; Siewert, R.M.

    1992-01-01

    Natural gas has considerable potential as an alternative automotive fuel. This paper reports on methane, the principal hydrocarbon species in natural-gas engine exhaust, which has extremely low photochemical reactivity but is a powerful greenhouse gas. Therefore, exhaust emissions of unburned methane from natural-gas vehicles are of particular concern. This laboratory reactor study evaluates noble metal catalysts for their potential in the catalytic removal of methane from natural-gas vehicle exhaust. Temperature run-up experiments show that the methane oxidation activity decreases in the order Pd/Al 2 O 3 > Rh/Al 2 O 3 > Pt/Al 2 O 3 . Also, for all the noble metal catalysts studied, methane conversion can be maximized by controlling the O 2 concentration of the feedstream at a point somewhat rich (reducing) of stoichiometry

  9. Trace Metal Requirements and Interactions in Symbiodinium kawagutii

    Directory of Open Access Journals (Sweden)

    Irene B. Rodriguez

    2018-02-01

    Full Text Available Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and its interaction with other divalent metals. We found that low Zn availability significantly decreases growth rates and results in elevated intracellular Mn, Co, Ni, and Fe quotas in the dinoflagellate. The results highlight the complex interaction among trace metals in S. kawagutii and suggest either metal replacement strategy to counter low Zn availability or enhanced uptake of other metals by non-specific divalent metal transporters. In this work, we also examined the Fe requirement of S. kawagutii using continuous cultures. We validated that 500 pM of Fe′ was sufficient to support maximum cell density during steady state growth period either at 26 or 28°C. This study shows that growth of S. kawagutii was limited by metal availability in the following order, Fe > Zn > Mn > Cu > Ni > Co. The fundamental information obtained for the free-living Symbiodinium shall provide insights into how trace metal availability, either from ambient seawater or hosts, affects growth and proliferation of symbiotic dinoflagellates and the interaction between symbiont and their hosts.

  10. Hair as an indicator of the body burden of metals in relation to age

    International Nuclear Information System (INIS)

    Kostial, K.

    1993-01-01

    Many factors influencing metal deposition in hair are still unknown. Animal experiments were performed to obtain data on the mechanism of transfer of elements into hair and to estimate whether hair retention is influenced by age, sex and chelating agent treatment. Experiments were performed on albino rats (Wistar strain) of different age and sex. Whole body hair (skin included) and organ retention of various elements was determined at different periods of time after intraperitoneal administration of the radioactive isotopes 115m Cd, 203 Hg, 54 Mn, 59 Fe, 65 Zn, 141 Ce, 137 Cs, 203 Pb and 85 Sr. In some experiments DTPA was used for reducing body retention of 155m Cd and 141 Ce and DMPS for reducing 203 Hg retention. Results show that hair and organ retention of elements in rats varies with age, sex and chelation treatment and such changes are specific for each element and can not be generalized. Age as a factor influencing hair retention of metals is likely to be more important for some elements than for others. In kinetic studies we found that due to differences in element distribution and kinetics, the relationship between hair and organ retention at various time intervals varies both with age and the element concerned. Sex influences not only hair but also metal retention and distribution in other organs. (author). 4 refs

  11. Development of 4S and related technologies (2). Long life metallic fuel

    International Nuclear Information System (INIS)

    Yacout, A.M.; Tsuboi, Y.; Ueda, N.

    2009-01-01

    This paper provides an overview of the long life metallic fuel to be used in the 4S reactor. The 4S fuel design is presented and implications of its characteristics on fuel performance are discussed. Main design characteristics include the long fuel life time of 30 years and the wider and longer fuel pins compared to EBR-II and FFTF fuel pins. The LIFE-METAL fuel performance code was used to evaluate the performance of the 4S fuel design. The code has been validated using post irradiation examination data of metallic fuel irradiated in EBR-II. The performance evaluation shows the benign nature of the design. The design enables the fuel to perform adequately during reactor operations without violating any of a conservative set of steady state design criteria. A survey evaluation of the fuel performance is also presented. This performance bounding evaluation took into account possible fuel swelling behavior and cladding temperature range that represents worst case scenarios. The evaluation showed that the fuel maintains its integrity even under those worst case conditions. (author)

  12. Dispersion relation and electron acceleration in the combined circular and elliptical metallic-dielectric waveguide filled by plasma

    Science.gov (United States)

    Abdoli-Arani, A.; Montazeri, M. M.

    2018-04-01

    Two special types of metallic waveguide having dielectric cladding and plasma core including the combined circular and elliptical structure are studied. Longitudinal and transverse field components in the different regions are obtained. Applying the boundary conditions, dispersion relations of the electromagnetic waves in the structures are obtained and then plotted. The acceleration of an injected external relativistic electron in the considered waveguides is studied. The obtained differential equations related to electron motion are solved by the fourth-order Runge-Kutta method. Numerical computations are made, and the results are graphically presented.

  13. Heavy metals in wild boar (Sus scrofa and related lesions

    Directory of Open Access Journals (Sweden)

    A. Zaccaroni

    2003-10-01

    Full Text Available Heavy metals are toxic elements naturally present in the environment which can be bioconcentrated by plants and animals and incorporated into food cycles. Thus the use of wildlife species as monitors is a useful tool to assess environmental pollution. Because of its ethological characteristics, wild boar is highly probable to be exposed to pollution, mainly by heavy metals. These pollutants, when present at high enough concentrations, can induce histological lesion in various tissues. The purpose of the present work was to investigate the levels of five metals (cadmium, copper, iron, lead and zinc in wild boar, Sus scrofa, originating from an Apennine area of Emilia Romagna, Northern Italy, and to evaluate any possible correlation with histological lesions eventually observed. Samples of several organs (liver, heart, kidney, diaphragm, abductor muscle, masseter, eye, testis, brain, lung and spleen were collected from hunted animals during winter 2001. Levels of metals were determined on freeze dried tissues employing microwave wet digestion. Toxicological analysis were performed by atomic absorption spectrophotometry and data expressed on a dry weight basis. Histopatological analyses were performed on fixed samples of the same tissue. Highest mean values were found in kidney for cadmium and copper (7 ± 1 ppm and 30 ± 2.6 ppm respectively and in liver for copper (21.16 ± 3.28 ppm, lead (2139 ± 680.6 ppb, iron (415.92 ± 24.41 ppm and zinc (94.76 ± 6.11 ppm. In all other tissues, mean concentrations of each metal were at low levels, and were comparable one another. A statistical difference was found for iron (p<0.05, copper (p<0.05 and cadmium (p<0.01 in kidney, in testis (p<0.01 for zinc and in liver for copper (p<0.05 and cadmium (p<0.01 as function of age cohorts. When sex was considered, a statistical difference was found for iron in eye, for copper in heart and for cadmium in heart and kidney. Histopatological analysis allowed

  14. Deposition kinetics of extracellular polymeric substances (EPS) on silica in monovalent and divalent salts.

    Science.gov (United States)

    Zhu, Pingting; Long, Guoyu; Ni, Jinren; Tong, Meiping

    2009-08-01

    The deposition kinetics of extracellular polymeric substances (EPS) on silica surfaces were examined in both monovalent and divalent solutions under a variety of environmentally relevant ionic strength and pH conditions by employing a quartz crystal microbalance with dissipation (DCM-D). Soluble EPS (SEPS) and bound EPS (BEPS) were extracted from four bacterial strains with different characteristics. Maximum favorable deposition rates (k(fa)) were observed for all EPS at low ionic strengths in both NaCl and CaCl2 solutions. With the increase of ionic strength, k(fa) decreased due to the simultaneous occurrence of EPS aggregation in solutions. Deposition efficiency (alpha; the ratio of deposition rates obtained under unfavorable versus corresponding favorable conditions) for all EPS increased with increasing ionic strength in both NaCl and CaCl2 solutions, which agreed with the trends of zeta potentials and was consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Comparison of alpha for SEPS and BEPS extracted from the same strain showed that the trends of alpha did not totally agree with trends of zeta potentials, indicating the deposition kinetics of EPS on silica surfaces were not only controlled by DLVO interactions, but also non-DLVO forces. Close comparison of alpha for EPS extracted from different sources showed alpha increased with increasing proteins to polysaccharides ratio. Subsequent experiments for EPS extracted from the same strain but with different proteins to polysaccharides ratios and from activated sludge also showed that alpha were largest for EPS with greatest proteins to polysaccharides ratio. Additional experiments for pure protein and solutions with different pure proteins to pure saccharides ratios further corroborated that larger proteins to polysaccharides ratio resulted in greater EPS deposition.

  15. Sorption of trace amounts of 67Ga and 65Zn on some divalent and trivalent metal hydroxides

    International Nuclear Information System (INIS)

    Music, S.; Sipalo-Zuljevic, J.; Vlatkovic, M.

    1977-01-01

    Trace concentrations of 67 Ga and 65 Zn were applied to the radiochemical study of sorption using Al(III), Cr(III), Fe(III), In(III), La(III), Zn(II), Cu(II) and Ni(II) hydroxides as sorbents. The results are given in terms of percentages sorbed, depending on solution pH or on the time of contact between the heterofeneous phases. The percentage sorbed is strongly pH-dependent. Sorption curves for 67 Ga show the maximum sorption (about 100%) starting from the pH values at the onset of the sorbent precipitation and ending with their approximate isoelectric point. Further increase in pH leads to a sudden decrease of the amounts sorbed. The sorption of 65 Zn is also pH-dependent; the decrease of sorption proceeds from right-to-left on the pH scale, i.e. in reverse direction if compared with gallium. The results are explained in terms of coprecipitation, electrostatic attraction (repulsion) and Van der Waals induced dipole attraction. Some sorption results, concerning the contact time dependence of the sorption are discussed in terms of specific sorption controlled by the diffusion of sorbate into the solid sorbent. (author)

  16. Divalent metal transporter 1 regulates iron-mediated ROS and pancreatic ß cell fate in response to cytokines

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Tonnesen, Morten Fog; Madsen, Andreas Nygaard

    2012-01-01

    Reactive oxygen species (ROS) contribute to target-cell damage in inflammatory and iron-overload diseases. Little is known about iron transport regulation during inflammatory attack. Through a combination of in vitro and in vivo studies, we show that the proinflammatory cytokine IL-1ß induces...... knockout islets is defective, highlighting a physiological role of iron and ROS in the regulation of insulin secretion. Dmt1 knockout mice are protected against multiple low-dose streptozotocin and high-fat diet-induced glucose intolerance, models of type 1 and type 2 diabetes, respectively. Thus, ß cells...

  17. Cyclopiazonic Acid Is Complexed to a Divalent Metal Ion When Bound to the Sarcoplasmic Reticulum Ca2+-ATPase

    DEFF Research Database (Denmark)

    Laursen, Mette; Bublitz, Maike; Moncoq, Karine

    2009-01-01

    is expected to be part of the cytoplasmic cation access pathway. Our model is consistent with the biochemical data on CPA function and provides new measures in structure-based drug design targeting Ca2+-ATPases, e. g. from pathogens. We also present an extended structural basis of ATP modulation pinpointing...

  18. Intensity-modulated polarizabilities and magic trapping of alkali-metal and divalent atoms in infrared optical lattices

    Science.gov (United States)

    Topcu, Turker; Derevianko, Andrei

    2014-05-01

    Long range interactions between neutral Rydberg atoms has emerged as a potential means for implementing quantum logical gates. These experiments utilize hyperfine manifold of ground state atoms to act as a qubit basis, while exploiting the Rydberg blockade mechanism to mediate conditional quantum logic. The necessity for overcoming several sources of decoherence makes magic wavelength trapping in optical lattices an indispensable tool for gate experiments. The common wisdom is that atoms in Rydberg states see trapping potentials that are essentially that of a free electron, and can only be trapped at laser intensity minima. We show that although the polarizability of a Rydberg state is always negative, the optical potential can be both attractive or repulsive at long wavelengths (up to ~104 nm). This opens up the possibility of magic trapping Rydberg states with ground state atoms in optical lattices, thereby eliminating the necessity to turn off trapping fields during gate operations. Because the wavelengths are near the CO2 laser band, the photon scattering and the ensuing motional heating is also reduced compared to conventional traps near low lying resonances, alleviating an important source of decoherence. This work was supported by the National Science Foundation (NSF) Grant No. PHY-1212482.

  19. Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study

    International Nuclear Information System (INIS)

    Margrete Meltzer, Helle; Lise Brantsaeter, Anne; Borch-Iohnsen, Berit; Ellingsen, Dag G.; Alexander, Jan; Thomassen, Yngvar; Stigum, Hein; Ydersbond, Trond A.

    2010-01-01

    Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin 2 for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110≤Hb<120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the body's handling of these metals.

  20. Alkali Metal Ion Complexes with Phosphates, Nucleotides, Amino Acids, and Related Ligands of Biological Relevance. Their Properties in Solution.

    Science.gov (United States)

    Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Lando, Gabriele; Milea, Demetrio; Sammartano, Silvio

    2016-01-01

    Alkali metal ions play very important roles in all biological systems, some of them are essential for life. Their concentration depends on several physiological factors and is very variable. For example, sodium concentrations in human fluids vary from quite low (e.g., 8.2 mmol dm(-3) in mature maternal milk) to high values (0.14 mol dm(-3) in blood plasma). While many data on the concentration of Na(+) and K(+) in various fluids are available, the information on other alkali metal cations is scarce. Since many vital functions depend on the network of interactions occurring in various biofluids, this chapter reviews their complex formation with phosphates, nucleotides, amino acids, and related ligands of biological relevance. Literature data on this topic are quite rare if compared to other cations. Generally, the stability of alkali metal ion complexes of organic and inorganic ligands is rather low (usually log K  Na(+) > K(+) > Rb(+) > Cs(+). For example, for citrate it is: log K ML = 0.88, 0.80, 0.48, 0.38, and 0.13 at 25 °C and infinite dilution. Some considerations are made on the main aspects related to the difficulties in the determination of weak complexes. The importance of the alkali metal ion complexes was also studied in the light of modelling natural fluids and in the use of these cations as probes for different processes. Some empirical relationships are proposed for the dependence of the stability constants of Na(+) complexes on the ligand charge, as well as for correlations among log K values of NaL, KL or LiL species (L = generic ligand).

  1. Serum heavy metals and hemoglobin related compounds in Saudi Arabia firefighters

    Directory of Open Access Journals (Sweden)

    Al-Malki Abdulrahman L

    2009-07-01

    Full Text Available Abstract Background Firefighters are frequently exposed to significant concentrations of hazardous materials including heavy metals, aldehydes, hydrogen chloride, dichlorofluoromethane and some particulates. Many of these materials have been implicated in the triggering of several diseases. The aim of the present study is to investigate the effect of fire smoke exposure on serum heavy metals and possible affection on iron functions compounds (total iron binding capacity, transferrin saturation percent, ferritin, unsaturated iron-binding capacity blood hemoglobin and carboxyhemoglobin,. Subjects and methods Two groups of male firefighter volunteers were included; the first included 28 firefighters from Jeddah city, while the second included 21 firefighters from Yanbu city with an overall age rang of 20–48 years. An additional group of 23 male non-firefighters volunteered from both cities as normal control subjects. Blood samples were collected from all volunteer subjects and investigated for relevant parameters. Results The results obtained showed that there were no statistically significant changes in the levels of serum heavy metals in firefighters as compared to normal control subjects. Blood carboxyhemoglobin and serum ferritin were statistically increased in Jeddah firefighters, (p Conclusion Such results might point to the need for more health protective and prophylactic measures to avoid such hazardous health effects (elevated Blood carboxyhemoglobin and serum ferritin and decreased serum TIBC and UIBC that might endanger firefighters working under dangerous conditions. Firefighters must be under regular medical follow-up through standard timetabled medical laboratory investigations to allow for early detection of any serum biochemical or blood hematological changes.

  2. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose-5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-d-ribosyl a-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... enzymes were dependent on the metal ion present, suggesting a function of the investigated aspartic acid residues both in the binding of ribose 5-phosphate, possibly via a divalent metal ion, and in the interaction with a divalent metal ion during catalysis....

  3. New synthesis ways of supported metallic catalysts and structure-reactivity relations in catalysis by metals; Nouvelles voies de syntheses de catalyseurs metalliques supportes et relations structure-reactivite en catalyse par les metaux

    Energy Technology Data Exchange (ETDEWEB)

    Uzio, D.

    2006-01-15

    This work deals with some research studies in the field of supported metallic catalysts. In all these works have been studied the characteristics bound to the active sites and the relations between these characteristics and the catalytic performances. The genesis of colloidal suspensions of transition metallic oxide has been used for the preparation of selective hydrogenation catalysts. At first studied in the case of palladium, this new synthesis way has been used for other metals such as Pt, Ni or Co. These studies have then been developed for preparing bimetallic catalysts (PdSn) with as supplementary aim the control of the homogeneity of the bimetallic character at the scale of nano-metric particles. These works have particularly allowed to specify the chemistry of the solutions of some metallic complexes and to rationalize the chemical processes carried out in the usual fabrication processes. Studies on size effects and the study of the reactivity of the nano and sub nano-metric particle have then been developed. Indeed, the clusters containing some atoms can see their intrinsic properties varied very strongly under the influence of several parameters as the number of atoms, the nature of the support, the reactional atmosphere. Using the knowledge acquired during the preceding works (chemistry of palladium aqueous solutions), the study of new methods of preparation of particles containing very few atoms has brought new data on the properties of hyper dispersed particles as well as on the principle of sensitivity to structure. The contribution of the support to the catalytic process for the hydrogenation of different substrates has been studied too. (O.M.)

  4. On the mass-metallicity relation, velocity dispersion and gravitational well depth of GRB host galaxies

    DEFF Research Database (Denmark)

    Arabsalmani, Maryam; Møller, Palle; Fynbo, Johan P. U.

    2015-01-01

    -DLA samples and compare the measured stellar masses for the four hosts where stellar masses have been determined from SED fits. We find excellent agreement and conclude that, on basis of all available data and tests, long duration GRB-DLA hosts and intervening QSO-DLAs are consistent with being drawn from...... away from the metallicity in the centre of the galaxy, second the path of the sightline through different parts of the potential well of the dark matter halo will cause different velocity fields to be sampled. We report evidence suggesting that this second effect may have been detected....

  5. Improvements in or relating to processes for reducing the oxygen content of metal oxides

    International Nuclear Information System (INIS)

    James, R.H.; Spooner, J.A.

    1980-01-01

    A process is described for reducing the oxygen content of a metal oxide material (such as an intimate mixture of uranium and plutonium oxides or a mixed oxide of uranium and plutonium) by contacting the material with a hydrogen-containing gas at an elevated temperature, wherein the material is contained in a plurality of carbon crucibles, each crucible having apertured ends and being otherwise a closed vessel, the crucibles being moved through a heated zone in end-to-end contact and thereby forming a duct through which the gas is passed counter-current to the direction of movement of the crucibles. (author)

  6. Soil-Plant Metal Relations in Panax notoginseng: An Ecosystem Health Risk Assessment

    Science.gov (United States)

    Ou, Xiaohong; Wang, Li; Guo, Lanping; Cui, Xiuming; Liu, Dahui; Yang, Ye

    2016-01-01

    This study features a survey of the content of heavy metals (Pb, Cd, Cr, As, Hg and Cu) in root and cultivation soils of Panax notoginseng (P. notoginseng), carried out in China’s Yunnan Province. The average contents of Pb, Cd, Cr, As, Hg, and Cu in the soil were 61.6, 0.4, 102.4, 57.1, 0.3, and 35.1 mg·kg−1, respectively. The heavy metals’ pollution indexes can be ranked as follows: As > Cd > Hg > Cu > Cr > Pb. The proportion of soil samples at slight, middle, strong, very strong, and extremely strong levels of potential environmental risk had values of 5.41%, 21.62%, 35.14%, 10.81%, and 27.03%, respectively. The potential environment risk index (RI) showed that 29.73% out of the total sample sites were above the level of strong and extremely strong. The ranges of Pb, Cd, Cr, As, Hg, and Cu content in tuber were 0.04–3.26, 0.04–0.33, 0.22–5.4, 0.10–1.8, 0.00–0.02, and 5.0–20.9 mg·kg−1, respectively. In combination with P. notoginseng consumption data, the estimated heavy metal daily intakes (EDIs) were 0.08–0.23, 0.006–0.019, 0.17–0.52, 0.04–0.12, 0.001–0.002, and 0.59–1.77 μg·kg−1·bw/day. All target hazard quotients (THQs) of individual elements and hazard indexes (HI) were less than one. The present study indicates that most of the P. notoginseng cultivation soil in the province of Yunnan presented slight and moderate ecological risk. Thus, more attention should be given to the heavy metals As, Cd, and Hg when selecting planting areas for the cultivation of P. notoginseng. Health risks associated with the intake of a single element or consumption of the combined metals through P. notoginseng are absent. PMID:27827951

  7. Assessment of complex water pollution with heavy metals and Pyrethroid pesticides on transcript levels of metallothionein and immune related genes.

    Science.gov (United States)

    Ghazy, Haneen A; Abdel-Razek, Mohamed A S; El Nahas, Abeer F; Mahmoud, Shawky

    2017-09-01

    Alteration of immunological function of an aquatic organism can be used as an indicator for evaluating the direct effect of exposure to pollutants. The aim of this work is to assess the impact of complex water pollution with special reference to Pyrethroid pesticides and heavy metals on mRNA transcript levels of Metallothionine and some immune related genes of Nile tilapia (Oreochromas Niloticus). Residues of six heavy metals and six Pyrethroid were assessed in water as well as fish tissues at three different sites of Lake Burullus, located at Northern Egypt. Variations of water physicochemical properties associated with different levels of heavy metals at the three different sections were recorded. Tissue residues of Fe, Mn and Zn, Cu, Ni exceed water levels in contrast to elevated water level of Pb. All assessed Pyrethroids are detected in fish tissue samples with higher concentration (3-42 folds) than that found in water samples especially Cypermethrin. Significant down-regulation of expression levels of metallothionein (MT) at the three sections of the lake was observed. The expression of immune related genes (IgM) and inflammatory cytokines (TNF, IL.8 and IL.1) were affected. IgM and TNF were significantly down-regulated at eastern and western section of the lake; meanwhile the expression of IL8 is down regulated at the three sections of the lack. IL1 was significantly up-regulated at eastern and middle sections. We conclude that, variable gene expression of MT and immune-related genes at the three sections of the lack impose different response to complex water pollution in relation to variable aquatic environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Iron and iron-related proteins in asbestosis.

    Science.gov (United States)

    ABSTRACT: We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FP...

  9. Six sigma implementation and its effects on configuration management related to metal industry

    International Nuclear Information System (INIS)

    Tariq, M.M.; Ahmad, S.F.; Mahmoo, A.; Kalsoom, T.

    2006-01-01

    This paper discusses the implementation of Six Sigma and its effects on Configuration Management (CM) of metal industry. The basic idea behind the Six Sigma philosophy is to continuously reduce product and process variation. Design for Six Sigma (DFSS) methodology generates new processes, products, services, plants, etc., whereas Define, Measure, Analyze, Improve and Control (DMAIC) methodology improves existing processes, products, services, designs, plants, etc. The DFSS project stages are summarized as Identify, Design, Optimize, and Validate (IDOV). Role of CM for DFSS and DMAIC will be discussed. Seven steps for Six Sigma introduction in new management strategy and the other seven steps for Six Sigma improvement implementation shall be discussed indicating possible role of CM. Tasks of Black Belt leader in Six Sigma implementation are very important. The expected outcomes of Six Sigma efforts are: Faster and more robust product development. More efficient and capable manufacturing processes and, more confident overall business performance. The investigation and knowledge of Six Sigma effects produced in metals industry on CM will increase the effectiveness of each other, and it will be a better, reliable and well documented approach towards Six Sigma. (author)

  10. Mandibular remodeling measured on cephalograms. 1. Osseous changes relative to superimposition on metallic implants.

    Science.gov (United States)

    Baumrind, S; Ben-Bassat, Y; Korn, E L; Bravo, L A; Curry, S

    1992-08-01

    We report the results of a study aimed at quantifying remodeling of mandibular surfaces in a sample of growing children who represent those usually treated by orthodontists in the mixed and early adult dentition. The sample, 31 patients with metallic implants of the Björk-type, was monitored at annual intervals between 8 1/2 and 15 1/2 years of age. (Maxillary remodeling changes for the sample have been reported earlier.) The present article reports findings concerning changes at condyle, gonion, menton, pogonion, and point B as identified on lateral cephalograms. Data are reported in the Frankfort plane frame of reference with the cephalograms from different time points superimposed on the metallic implants. Mean displacement at condyle was larger than that at any other landmark and was similar in magnitude and direction to the observations of Björk when the difference in orientation of the vertical axis in the two studies is taken into account. The mean displacement of gonion was in an upward and backward direction at an angle of approximately 45 degrees to the Frankfort plane. Mean displacements at menton and pogonion were in a downward and backward direction but were very small. Mean displacement at point B was somewhat greater than that of menton and gonion, oriented in an upward and backward direction. Individual variation for most of the parameters measured was sufficiently large to warrant the inference that caution should be used when mean values are applied to the analysis of individual cases.

  11. Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

    International Nuclear Information System (INIS)

    Jabran Zahid, H.; Kudritzki, Rolf-Peter; Ho, I-Ting; Conroy, Charlie; Andrews, Brett

    2017-01-01

    We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

  12. Stellar Absorption Line Analysis of Local Star-forming Galaxies: The Relation between Stellar Mass, Metallicity, Dust Attenuation, and Star Formation Rate

    Energy Technology Data Exchange (ETDEWEB)

    Jabran Zahid, H. [Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Kudritzki, Rolf-Peter; Ho, I-Ting [University of Hawaii at Manoa, Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Conroy, Charlie [Department of Astronomy, Harvard University, Cambridge, MA, 02138 (United States); Andrews, Brett, E-mail: zahid@cfa.harvard.edu [PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O’Hara Street, Pittsburgh, PA 15260 (United States)

    2017-09-20

    We analyze the optical continuum of star-forming galaxies in the Sloan Digital Sky Survey by fitting stacked spectra with stellar population synthesis models to investigate the relation between stellar mass, stellar metallicity, dust attenuation, and star formation rate. We fit models calculated with star formation and chemical evolution histories that are derived empirically from multi-epoch observations of the stellar mass–star formation rate and the stellar mass–gas-phase metallicity relations, respectively. We also fit linear combinations of single-burst models with a range of metallicities and ages. Star formation and chemical evolution histories are unconstrained for these models. The stellar mass–stellar metallicity relations obtained from the two methods agree with the relation measured from individual supergiant stars in nearby galaxies. These relations are also consistent with the relation obtained from emission-line analysis of gas-phase metallicity after accounting for systematic offsets in the gas-phase metallicity. We measure dust attenuation of the stellar continuum and show that its dependence on stellar mass and star formation rate is consistent with previously reported results derived from nebular emission lines. However, stellar continuum attenuation is smaller than nebular emission line attenuation. The continuum-to-nebular attenuation ratio depends on stellar mass and is smaller in more massive galaxies. Our consistent analysis of stellar continuum and nebular emission lines paves the way for a comprehensive investigation of stellar metallicities of star-forming and quiescent galaxies.

  13. The Effect of Susceptibility Artifacts Related to Metallic Implants on Adjacent-Lesion Assessment in Simultaneous TOF PET/MR.

    Science.gov (United States)

    Svirydenka, Hanna; Delso, Gaspar; De Galiza Barbosa, Felipe; Huellner, Martin; Davison, Helen; Fanti, Stefano; Veit-Haibach, Patrick; Ter Voert, Edwin E G W

    2017-07-01

    Metalic implants may affect attenuation correction (AC) in PET/MR imaging. The purpose of this study was to evaluate the effect of susceptibility artifacts related to metallic implants on adjacent metabolically active lesions in clinical simultaneous PET/MR scanning for both time-of-flight (TOF) and non-TOF reconstructed PET images. Methods: We included 27 patients without implants but with confirmed 18 F-FDG-avid lesions adjacent to common implant locations. In all patients, a clinically indicated whole-body 18 F-FDG PET/MR scan was acquired. Baseline non-TOF and TOF PET images were reconstructed. Reconstruction was repeated after the introduction of artificial signal voids in the AC map to simulate metallic implants in standard anatomic areas. All reconstructed images were qualitatively and quantitatively assessed and compared with the baseline images. Results: In total, 51 lesions were assessed. In 40 and 50 of these cases (non-TOF and TOF, respectively), the detectability of the lesions did not change; in 9 and 1 cases, the detectability changed; and in 2 non-TOF cases, the lesions were no longer visible after the introduction of metallic artifacts. The inclusion of TOF information significantly reduced artifacts due to simulated implants in the femoral head, sternum, and spine ( P = 0.01, 0.01, and 0.03, respectively). It also improved image quality in these locations ( P = 0.02, 0.01, and 0.01, respectively). The mean percentage error was -3.5% for TOF and -4.8% for non-TOF reconstructions, meaning that the inclusion of TOF information reduced the percentage error in SUV max by 28.5% ( P metallic implants have a significant effect on small, moderately 18 F-FDG-avid lesions near the implant site that possibly may go unnoticed without TOF information. On larger, highly 18 F-FDG-avid lesions, the metallic implants had only a limited effect. The largest significant quantitative difference was found in artifacts of the sternum. There was only a weak inverse

  14. THE QUEST FOR CRADLES OF LIFE: USING THE FUNDAMENTAL METALLICITY RELATION TO HUNT FOR THE MOST HABITABLE TYPE OF GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Dayal, Pratika [Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Cockell, Charles [UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3HJ (United Kingdom); Rice, Ken [Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Mazumdar, Anupam [Consortium for Fundamental Physics, Lancaster University, Lancaster LA1 4 YB (United Kingdom)

    2015-09-01

    The field of astrobiology has made huge strides in understanding the habitable zones around stars (stellar habitable zones) where life can begin, sustain its existence and evolve into complex forms. A few studies have extended this idea by modeling galactic-scale habitable zones (galactic habitable zones) for our Milky Way (MW) and specific elliptical galaxies. However, estimating the habitability for galaxies spanning a wide range of physical properties has so far remained an outstanding issue. Here, we present a “cosmobiological” framework that allows us to sift through the entire galaxy population in the local universe and answer the question, “Which type of galaxy is most likely to host complex life in the cosmos?” Interestingly, the three key astrophysical criteria governing habitability (total mass in stars, total metal mass and ongoing star formation rate) are found to be intricately linked through the “fundamental metallicity relation” as shown by Sloan Digital Sky Survey observations of more than a hundred thousand galaxies in the local universe. Using this relation we show that metal-rich, shapeless giant elliptical galaxies at least twice as massive as the MW (with a tenth of its star formation rate) can potentially host ten thousand times as many habitable (Earth-like) planets, making them the most probable “cradles of life” in the universe.

  15. THE QUEST FOR CRADLES OF LIFE: USING THE FUNDAMENTAL METALLICITY RELATION TO HUNT FOR THE MOST HABITABLE TYPE OF GALAXY

    International Nuclear Information System (INIS)

    Dayal, Pratika; Cockell, Charles; Rice, Ken; Mazumdar, Anupam

    2015-01-01

    The field of astrobiology has made huge strides in understanding the habitable zones around stars (stellar habitable zones) where life can begin, sustain its existence and evolve into complex forms. A few studies have extended this idea by modeling galactic-scale habitable zones (galactic habitable zones) for our Milky Way (MW) and specific elliptical galaxies. However, estimating the habitability for galaxies spanning a wide range of physical properties has so far remained an outstanding issue. Here, we present a “cosmobiological” framework that allows us to sift through the entire galaxy population in the local universe and answer the question, “Which type of galaxy is most likely to host complex life in the cosmos?” Interestingly, the three key astrophysical criteria governing habitability (total mass in stars, total metal mass and ongoing star formation rate) are found to be intricately linked through the “fundamental metallicity relation” as shown by Sloan Digital Sky Survey observations of more than a hundred thousand galaxies in the local universe. Using this relation we show that metal-rich, shapeless giant elliptical galaxies at least twice as massive as the MW (with a tenth of its star formation rate) can potentially host ten thousand times as many habitable (Earth-like) planets, making them the most probable “cradles of life” in the universe

  16. Mobilisation of heavy metals into the urine by CaEDTA: relation to erythrocyte and plasma concentrations and exposure indicators.

    Science.gov (United States)

    Araki, S; Aono, H; Murata, K

    1986-09-01

    To investigate the effects of calcium disodium ethylenediamine tetra-acetate (CaEDTA) on the urinary excretion, erythrocyte, and plasma concentrations and exposure indicators of seven heavy metals, CaEDTA was administered by intravenous infusion to 20 workers exposed to lead, zinc, and copper. The workers' blood lead concentrations ranged from 22 to 59 micrograms/dl (mean 38 micrograms/dl (1.8 mumol/l]. The 24 hour urinary excretion of metals after CaEDTA administration (mobilisation yield) was on average 13 times the background excretion for lead, 11 times for zinc, 3.8 times for manganese, 3.4 times for cadmium, 1.3 times for copper, and 1.1 times for chromium; no significant increase was found for mercury. The mobilisation yield of lead (MPb) was significantly correlated with whole blood and erythrocyte concentrations and the urinary excretion of lead but not with its plasma concentration; similarly, the mobilisation yield of cadmium was significantly correlated with its erythrocyte concentration. In addition, MPb was significantly correlated with intra-erythrocytic enzyme delta-aminolaevulinic acid dehydratase activity and urinary coproporphyrin excretion. The relation between the mobilisation yield of heavy metals and their body burden (and toxic signs) is discussed in the light of these findings.

  17. Assessment of heavy metal accumulation in two species of Tillandsia in relation to atmospheric emission sources in Argentina

    International Nuclear Information System (INIS)

    Wannaz, Eduardo D.; Carreras, Hebe A.; Perez, Carlos A.; Pignata, Maria L.

    2006-01-01

    The ability of Tillandsia capillaris Ruiz and Pav. f. capillaris and Tillandsia permutata A. Cast. to accumulate heavy metals was evaluated in relation to potential atmospheric emission sources in Argentina. The sampling areas (n = 38) were chosen in the province of Cordoba, located in the center of Argentina, and categorized according to land use, anthropogenic activities and/or distance to potential heavy metal emission sources. In each sampling site, pools of 40-50 individuals of each species were made from plants collected along the four cardinal directions. The concentrations of V, Mn, Fe, Co, Ni, Cu, Zn, Pb and Br of these samples were measured by Total Reflection X-Ray Fluorescence (TXRF) analysis with Synchrotron Radiation. Each species was submitted to a cluster analysis in order to discriminate different groups of heavy metals as tracers of natural or anthropogenic sources. A Contamination Factor (CF) was calculated using the concentrations of the elements in each sample compared to their concentrations in the control samples. Finally, the rank coefficients of correlation between the CFs and the categorical variables characteristic of each site (land use and anthropogenic load) were analyzed. A positive correlation was found for T. capillaris between the CFs of V, Mn, Co, Ni, Cu and Zn and the urban-industrial category, whereas the CF values for Zn and Pb were positively correlated with the road category. In T. permutata there was a positive correlation between the CF of Zn and the urban-industrial category and the CF of Pb with the road category. We therefore conclude that T. capillaris is a more efficient metal accumulator in passive biomonitoring studies

  18. Assessment of heavy metal accumulation in two species of Tillandsia in relation to atmospheric emission sources in Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Wannaz, Eduardo D. [Departamento de Quimica, Instituto Multidisciplinario de Biologia Vegetal - IMBIV/CONICET-UNC, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 1611, Ciudad Universitaria (X5016GCA) Cordoba (Argentina); Carreras, Hebe A. [Departamento de Quimica, Instituto Multidisciplinario de Biologia Vegetal - IMBIV/CONICET-UNC, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 1611, Ciudad Universitaria (X5016GCA) Cordoba (Argentina); Perez, Carlos A. [Laboratorio Nacional de Luz Sincrotron - LNLS/CNPq, Caixa Postal 6192, 13038-970 Campinas (Brazil); Pignata, Maria L. [Departamento de Quimica, Instituto Multidisciplinario de Biologia Vegetal - IMBIV/CONICET-UNC, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 1611, Ciudad Universitaria (X5016GCA) Cordoba (Argentina)]. E-mail: pignata@com.uncor.edu

    2006-05-15

    The ability of Tillandsia capillaris Ruiz and Pav. f. capillaris and Tillandsia permutata A. Cast. to accumulate heavy metals was evaluated in relation to potential atmospheric emission sources in Argentina. The sampling areas (n = 38) were chosen in the province of Cordoba, located in the center of Argentina, and categorized according to land use, anthropogenic activities and/or distance to potential heavy metal emission sources. In each sampling site, pools of 40-50 individuals of each species were made from plants collected along the four cardinal directions. The concentrations of V, Mn, Fe, Co, Ni, Cu, Zn, Pb and Br of these samples were measured by Total Reflection X-Ray Fluorescence (TXRF) analysis with Synchrotron Radiation. Each species was submitted to a cluster analysis in order to discriminate different groups of heavy metals as tracers of natural or anthropogenic sources. A Contamination Factor (CF) was calculated using the concentrations of the elements in each sample compared to their concentrations in the control samples. Finally, the rank coefficients of correlation between the CFs and the categorical variables characteristic of each site (land use and anthropogenic load) were analyzed. A positive correlation was found for T. capillaris between the CFs of V, Mn, Co, Ni, Cu and Zn and the urban-industrial category, whereas the CF values for Zn and Pb were positively correlated with the road category. In T. permutata there was a positive correlation between the CF of Zn and the urban-industrial category and the CF of Pb with the road category. We therefore conclude that T. capillaris is a more efficient metal accumulator in passive biomonitoring studies.

  19. Nickel hexacyanoferrate, a versatile intercalation host for divalent ions from nonaqueous electrolytes

    Science.gov (United States)

    Lipson, Albert L.; Han, Sang-Don; Kim, Soojeong; Pan, Baofei; Sa, Niya; Liao, Chen; Fister, Timothy T.; Burrell, Anthony K.; Vaughey, John T.; Ingram, Brian J.

    2016-09-01

    New energy storage chemistries based on Mg ions or Ca ions can theoretically improve both the energy density and reduce the costs of batteries. To date there has been limited progress in implementing these systems due to the challenge of finding a high voltage high capacity cathode that is compatible with an electrolyte that can plate and strip the elemental metal. In order to accelerate the discovery of such a system, model systems are needed that alleviate some of the issues of incompatibility. This report demonstrates the ability of nickel hexacyanoferrate to electrochemically intercalate Mg, Ca and Zn ions from a nonaqueous electrolyte. This material has a relatively high insertion potential and low overpotential in the electrolytes used in this study. Furthermore, since it is not an oxide based cathode it should be able to resist attack by corrosive electrolytes such as the chloride containing electrolytes that are often used to plate and strip magnesium. This makes it an excellent cathode for use in developing and understanding the complex electrochemistry of multivalent ion batteries.

  20. Indoor metallic pollution related to mining activity in the Bolivian Altiplano.

    Science.gov (United States)

    Fontúrbel, Francisco E; Barbieri, Enio; Herbas, Cristian; Barbieri, Flavia L; Gardon, Jacques

    2011-10-01

    The environmental pollution associated with mining and metallurgical activities reaches its greatest extent in several Andean cities and villages. Many locations in this area have accumulated through centuries a large amount of mining wastes, often disregarding the magnitude of this situation. However, in these naturally mineralized regions, there is little information available stating the exact role of mining and metallurgical industries in urban pollution. In this study, we demonstrated that the various metallic elements present in indoor dust (As, Cd, Cu, Pb, Sb, Sn, Zn) had a common origin and this contamination was increased by the proximity to the mines. Lead dust concentration was found at concerning levels for public health. In addition, wrong behaviors such as carrying mining workwear home contributed to this indoor dust pollution. Consequently, the constant exposure of the population could represent a potential health hazard for vulnerable groups, especially children. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Metal-Binding Ability of Leu-Enkephalin, Related Glycoconjugates and Peptidomimetics

    Directory of Open Access Journals (Sweden)

    Zsuzsa Majer

    2015-12-01

    Full Text Available Both the chemistry and consequences of the nonenzymatic reaction between reducing sugars and reactive amino groups of amino acids, peptides and proteins (known as the Maillard reaction, have received considerable attention in food and health science fields. This initial reaction results in Amadori and similar products formation, followed by degradation to advanced glycation end products (AGEs. It is well established that AGEs are associated with color and odor of thermally processed or stored food, as well as with pathogen products in a number of diseases. The model systems of early stage Maillard reaction products (MRP were prepared between endogenous opioid peptide leucine enkephalin (1 and D-glucose / D-glucuronic acid. The complexation ability of prepared MRP with metal ions (Ca2+, Zn2+, Al3+, Pb2+ and Cu2+ was investigated and compared to the complexation ability of parent peptide using ECD and FTIR spectroscopic measurements.

  2. THE GAS PHASE MASS METALLICITY RELATION FOR DWARF GALAXIES: DEPENDENCE ON STAR FORMATION RATE AND HI GAS MASS

    Energy Technology Data Exchange (ETDEWEB)

    Jimmy; Tran, Kim-Vy [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Saintonge, Amélie; Accurso, Gioacchino [Department of Physics and Astronomy, University College London, Gower Place, London WC1E 6BT (United Kingdom); Brough, Sarah; Oliva-Altamirano, Paola [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)

    2015-10-20

    Using a sample of dwarf galaxies observed using the VIMOS IFU on the Very Large Telescope, we investigate the mass–metallicity relation (MZR) as a function of star formation rate (FMR{sub SFR}) as well as HI-gas mass (FMR{sub HI}). We combine our IFU data with a subsample of galaxies from the ALFALFA HI survey crossmatched to the Sloan Digital Sky Survey (SDSS) to study the FMR{sub SFR} and FMR{sub HI} across the stellar mass range 10{sup 6.6}–10{sup 8.8} M{sub ⊙}, with metallicities as low as 12 + log(O/H) = 7.67. We find the 1σ mean scatter in the MZR to be 0.05 dex. The 1σ mean scatter in the FMR{sub SFR} (0.02 dex) is significantly lower than that of the MZR. The FMR{sub SFR} is not consistent between the IFU observed galaxies and the ALFALFA/SDSS galaxies for SFRs lower than 10{sup −2.4} M{sub ⊙} yr{sup −1}, however, this could be the result of limitations of our measurements in that regime. The lowest mean scatter (0.01 dex) is found in the FMR{sub HI}. We also find that the FMR{sub HI} is consistent between the IFU observed dwarf galaxies and the ALFALFA/SDSS crossmatched sample. We introduce the fundamental metallicity luminosity counterpart to the FMR, again characterized in terms of SFR (FML{sub SFR}) and HI-gas mass (FML{sub HI}). We find that the FML{sub HI} relation is consistent between the IFU observed dwarf galaxy sample and the larger ALFALFA/SDSS sample. However, the 1σ scatter for the FML{sub HI} relation is not improved over the FMR{sub HI} scenario. This leads us to conclude that the FMR{sub HI} is the best candidate for a physically motivated fundamental metallicity relation.

  3. EVOLUTION OF THE MASS-METALLICITY RELATIONS IN PASSIVE AND STAR-FORMING GALAXIES FROM SPH-COSMOLOGICAL SIMULATIONS

    International Nuclear Information System (INIS)

    Romeo Velonà, A. D.; Gavignaud, I.; Meza, A.; Sommer-Larsen, J.; Napolitano, N. R.; Antonuccio-Delogu, V.; Cielo, S.

    2013-01-01

    We present results from SPH-cosmological simulations, including self-consistent modeling of supernova feedback and chemical evolution, of galaxies belonging to two clusters and 12 groups. We reproduce the mass-metallicity (ZM) relation of galaxies classified in two samples according to their star-forming (SF) activity, as parameterized by their specific star formation rate (sSFR), across a redshift range up to z = 2. The overall ZM relation for the composite population evolves according to a redshift-dependent quadratic functional form that is consistent with other empirical estimates, provided that the highest mass bin of the brightest central galaxies is excluded. Its slope shows irrelevant evolution in the passive sample, being steeper in groups than in clusters. However, the subsample of high-mass passive galaxies only is characterized by a steep increase of the slope with redshift, from which it can be inferred that the bulk of the slope evolution of the ZM relation is driven by the more massive passive objects. The scatter of the passive sample is dominated by low-mass galaxies at all redshifts and keeps constant over cosmic times. The mean metallicity is highest in cluster cores and lowest in normal groups, following the same environmental sequence as that previously found in the red sequence building. The ZM relation for the SF sample reveals an increasing scatter with redshift, indicating that it is still being built at early epochs. The SF galaxies make up a tight sequence in the SFR-M * plane at high redshift, whose scatter increases with time alongside the consolidation of the passive sequence. We also confirm the anti-correlation between sSFR and stellar mass, pointing at a key role of the former in determining the galaxy downsizing, as the most significant means of diagnostics of the star formation efficiency. Likewise, an anti-correlation between sSFR and metallicity can be established for the SF galaxies, while on the contrary more active galaxies

  4. Spectral Analysis Related to Bare-Metal and Drug-Eluting Coronary Stent Implantation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Rose Mary Ferreira Lisboa da, E-mail: roselisboa@cardiol.br [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Silva, Carlos Augusto Bueno [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil); Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Greco, Otaviano José [Belo Horizonte, Hospital São João de Deus, Divinópolis, MG (Brazil); Moreira, Maria da Consolação Vieira [Faculdade de Medicina da UFMG, Divinópolis, MG (Brazil)

    2014-08-15

    The autonomic nervous system plays a central role in cardiovascular regulation; sympathetic activation occurs during myocardial ischemia. To assess the spectral analysis of heart rate variability during stent implantation, comparing the types of stent. This study assessed 61 patients (mean age, 64.0 years; 35 men) with ischemic heart disease and indication for stenting. Stent implantation was performed under Holter monitoring to record the spectral analysis of heart rate variability (Fourier transform), measuring the low-frequency (LF) and high-frequency (HF) components, and the LF/HF ratio before and during the procedure. Bare-metal stent was implanted in 34 patients, while the others received drug-eluting stents. The right coronary artery was approached in 21 patients, the left anterior descending, in 28, and the circumflex, in 9. As compared with the pre-stenting period, all patients showed an increase in LF and HF during stent implantation (658 versus 185 ms2, p = 0.00; 322 versus 121, p = 0.00, respectively), with no change in LF/HF. During stent implantation, LF was 864 ms2 in patients with bare-metal stents, and 398 ms2 in those with drug-eluting stents (p = 0.00). The spectral analysis of heart rate variability showed no association with diabetes mellitus, family history, clinical presentation, beta-blockers, age, and vessel or its segment. Stent implantation resulted in concomitant sympathetic and vagal activations. Diabetes mellitus, use of beta-blockers, and the vessel approached showed no influence on the spectral analysis of heart rate variability. Sympathetic activation was lower during the implantation of drug-eluting stents.

  5. Changes in Specific Surface as observed by NMR, caused by saturation of Chalk with porewater bearing divalent Ions

    DEFF Research Database (Denmark)

    Katika, Konstantina; Addassi, Mouadh; Alam, Mohammad Monzurul

    2014-01-01

    Nuclear Magnetic Resonance (NMR) spectrometry has proved to be a good technique for determining the petrophysical properties of reservoir rocks; such as porosity and pore size distribution. We investigated how pore water rich in divalent ions affect the NMR signal from chalk with two different de......-to-volume ratio of the pore space. The results of this work could benefit the ongoing study on the optimization of the water composition for Enhanced Oil Recovery (EOR) methods and shed light on how it can affect the mechanical and physical properties of the rock....

  6. Directly relating gas-phase cluster measurements to solution-phase hydrolysis, the absolute standard hydrogen electrode potential, and the absolute proton solvation energy.

    Science.gov (United States)

    Donald, William A; Leib, Ryan D; O'Brien, Jeremy T; Williams, Evan R

    2009-06-08

    Solution-phase, half-cell potentials are measured relative to other half-cell potentials, resulting in a thermochemical ladder that is anchored to the standard hydrogen electrode (SHE), which is assigned an arbitrary value of 0 V. A new method for measuring the absolute SHE potential is demonstrated in which gaseous nanodrops containing divalent alkaline-earth or transition-metal ions are reduced by thermally generated electrons. Energies for the reactions 1) M(H(2)O)(24)(2+)(g) + e(-)(g)-->M(H(2)O)(24)(+)(g) and 2) M(H(2)O)(24)(2+)(g) + e(-)(g)-->MOH(H(2)O)(23)(+)(g) + H(g) and the hydrogen atom affinities of MOH(H(2)O)(23)(+)(g) are obtained from the number of water molecules lost through each pathway. From these measurements on clusters containing nine different metal ions and known thermochemical values that include solution hydrolysis energies, an average absolute SHE potential of +4.29 V vs. e(-)(g) (standard deviation of 0.02 V) and a real proton solvation free energy of -265 kcal mol(-1) are obtained. With this method, the absolute SHE potential can be obtained from a one-electron reduction of nanodrops containing divalent ions that are not observed to undergo one-electron reduction in aqueous solution.

  7. Topological evolution and photoluminescent properties of a series of divalent zinc-based metal–organic frameworks tuned via ancillary ligating spacers

    International Nuclear Information System (INIS)

    Lian, Xiao-Min; Zhao, Wen; Zhao, Xiao-Li

    2013-01-01

    The combination of divalent zinc ions, 4-(4-carboxybenzamido)benzoic acid and exo-bidendate bipyridine ligands gave rise to a series of new MOFs: [ZnL(bipy)]·DMF·H 2 O (1), [ZnL(bpe)]·1.5H 2 O (2), [ZnL(bpa)]·4H 2 O (3) and [ZnL(bpp)]·1.75H 2 O (4) (MOF=metal-organic framework, bipy=4,4′-bipyridine, bpe=trans-1,2-bis(4-pyridyl)ethylene, bpa=1,2-bis(4-pyridinyl)ethane, bpp=1,3-bis(4-pyridinyl)propane, H 2 L=4,4′-(carbonylimino)dibenzoic acid). Fine tune over the topology of the MOFs was achieved via systematically varying the geometric length of the second ligating bipyridine ligands. Single-crystal X-ray analysis reveals that complex 1 has a triply interpenetrated three-dimensional (3D) framework with elongated primitive cubic topology, whereas isostructural complexes 2 and 3 each possesses a 6-fold interpenetrated diamondiod 3D framework. Further expansion of the length of the bipyridine ligand to bpp leads to the formation of 4, which features an interesting entangled architecture of 2D→3D parallel polycatenation. In addition, the thermogravimetric analyses and solid-state photoluminescent properties of the selected complexes are investigated. - Graphical abstract: The incorporation of exo-bidendate bipyridine spacers into the Zn–H 2 L system has yielded a series of new MOFs exhibiting topological evolution from 3-fold interpenetration to 6-fold interpenetration and 2D→3D parallel polycatenation. Highlights: ► The effect of the pyridyl-based spacers on the formation of MOFs was explored. ► Fine tune over the topology of the MOFs was achieved. ► An interesting structure of 2D→3D parallel polycatenation is reported

  8. BEP-relations for N2 dissociation over stepped transition metal and alloy surfaces

    DEFF Research Database (Denmark)

    Fronczek-Munter, Ture Rønved; Bligaard, Thomas; Christensen, Claus H.

    2008-01-01

    , a perfectly linear Bronsted-Evans-Polanyi (BEP) relation between the transition-state potential energy and the dissociative chemisorption energy is obtained. The perfect BEP relation, which extends over 12 eV in chemisorption energy, suggests that the manifestation of BEP relations for surface reactions...... is a general electronic structure effect, and that geometric effects are responsible for the scatter which is normally observed around the BEP line. The BEP relation is also shown to be valid for both surface and bulk alloys. The scatter is, however, larger than for the pure elements. This can be understood...

  9. Crystal structure and luminescence properties of the first hydride oxide chloride with divalent europium. LiEu{sub 2}HOCl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, Daniel; Schleid, Thomas [Institute for Inorganic Chemistry, University of Stuttgart (Germany); Enseling, David; Juestel, Thomas [Department of Chemical Engineering, Muenster University of Applied Sciences, Steinfurt (Germany)

    2017-11-17

    The mixed-anionic hydride oxide chloride LiEu{sub 2}HOCl{sub 2} with divalent europium was synthesized by the reduction of Eu{sub 2}O{sub 3} with LiH in a LiCl flux at 750 C for 4 d in silica-jacketed niobium capsules. According to structure determination by single-crystal X-ray diffraction the yellow compound crystallizes in the orthorhombic space group Cmcm (a = 1492.30(11) pm, b = 570.12(4) pm, c = 1143.71(8) pm, Z = 8) with a crystal structure closely related to that one of the quaternary hydride oxide LiLa{sub 2}HO{sub 3} and the hydride nitride LiSr{sub 2}H{sub 2}N. On the other hand it can also be derived from the PbFCl-type structure of EuHCl showing astonishingly short Eu{sup 2+}..Eu{sup 2+} contacts of 326 and 329 pm. Both crystallographically different Eu{sup 2+} cations have nine anionic neighbors, while all other ions (Li{sup +}, H{sup -}, O{sup 2-} and Cl{sup -}) reside in six-membered coordination spheres. LiEu{sub 2}OCl{sub 2}H exhibits a bright yellow luminescence with an emission maximum at 581 nm upon excitation at 440 nm. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Molecular diversity of arbuscular mycorrhizal fungi in relation to soil chemical properties and heavy metal contamination

    International Nuclear Information System (INIS)

    Zarei, Mehdi; Hempel, Stefan; Wubet, Tesfaye; Schaefer, Tina; Savaghebi, Gholamreza; Jouzani, Gholamreza Salehi; Nekouei, Mojtaba Khayam; Buscot, Francois

    2010-01-01

    Abundance and diversity of arbuscular mycorrhizal fungi (AMF) associated with dominant plant species were studied along a transect from highly lead (Pb) and zinc (Zn) polluted to non-polluted soil at the Anguran open pit mine in Iran. Using an established primer set for AMF in the internal transcribed spacer (ITS) region of rDNA, nine different AMF sequence types were distinguished after phylogenetic analyses, showing remarkable differences in their distribution patterns along the transect. With decreasing Pb and Zn concentration, the number of AMF sequence types increased, however one sequence type was only found in the highly contaminated area. Multivariate statistical analysis revealed that further factors than HM soil concentration affect the AMF community at contaminated sites. Specifically, the soils' calcium carbonate equivalent and available P proved to be of importance, which illustrates that field studies on AMF distribution should also consider important environmental factors and their possible interactions. - The molecular diversity of AMF was found to be influenced by a combination of soil heavy metal and other soil chemical parameters.

  11. Molecular diversity of arbuscular mycorrhizal fungi in relation to soil chemical properties and heavy metal contamination

    Energy Technology Data Exchange (ETDEWEB)

    Zarei, Mehdi [Department of Soil Science, College of Agriculture, University of Shiraz, Shiraz (Iran, Islamic Republic of); Hempel, Stefan, E-mail: hempel.stefan@googlemail.co [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany); Freie Universitaet Berlin, Institut fuer Biologie, Okologie der Pflanzen, Altensteinstrasse 6, 14195 Berlin (Germany); Wubet, Tesfaye; Schaefer, Tina [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany); Savaghebi, Gholamreza [Department of Soil Science Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj (Iran, Islamic Republic of); Jouzani, Gholamreza Salehi; Nekouei, Mojtaba Khayam [Agricultural Biotechnology Research Institute of Iran (ABRII), P.O. Box 31535-1897, Karaj (Iran, Islamic Republic of); Buscot, Francois [UFZ Helmholtz Centre for Environmental Research Leipzig-Halle, Department of Soil Ecology, Theodor-Lieser-Strasse 4, 06120 Halle (Germany)

    2010-08-15

    Abundance and diversity of arbuscular mycorrhizal fungi (AMF) associated with dominant plant species were studied along a transect from highly lead (Pb) and zinc (Zn) polluted to non-polluted soil at the Anguran open pit mine in Iran. Using an established primer set for AMF in the internal transcribed spacer (ITS) region of rDNA, nine different AMF sequence types were distinguished after phylogenetic analyses, showing remarkable differences in their distribution patterns along the transect. With decreasing Pb and Zn concentration, the number of AMF sequence types increased, however one sequence type was only found in the highly contaminated area. Multivariate statistical analysis revealed that further factors than HM soil concentration affect the AMF community at contaminated sites. Specifically, the soils' calcium carbonate equivalent and available P proved to be of importance, which illustrates that field studies on AMF distribution should also consider important environmental factors and their possible interactions. - The molecular diversity of AMF was found to be influenced by a combination of soil heavy metal and other soil chemical parameters.

  12. The Simple Metals and New Models of the Interacting-Electron-Gas Type: I. Anomalous Plasmon Dispersion Relations in Heavy Alkali Metals

    Science.gov (United States)

    Okuda, Takashi; Horio, Kohji; Ohmura, Yoshihiro; Mizuno, Yukio

    2018-06-01

    The well-known interacting-electron-gas model of metallic states is modified by replacing the Coulomb interaction by a truncated one to weaken the repulsive force between electrons at short distances. The new model is applied to the so-called simple metals and is found far superior to the old one. Most of the calculations are carried out successfully on the basis of the random-phase-approximation (RPA), which is known much too poor for the old familiar model. In the present paper the numerical value of the new parameter peculiar to the new model is determined systematically with the help of the observed plasmon spectrum for each metal.

  13. Conformational locking by design: relating strain energy with luminescence and stability in rigid metal-organic frameworks.

    Science.gov (United States)

    Shustova, Natalia B; Cozzolino, Anthony F; Dincă, Mircea

    2012-12-05

    Minimization of the torsional barrier for phenyl ring flipping in a metal-organic framework (MOF) based on the new ethynyl-extended octacarboxylate ligand H(8)TDPEPE leads to a fluorescent material with a near-dark state. Immobilization of the ligand in the rigid structure also unexpectedly causes significant strain. We used DFT calculations to estimate the ligand strain energies in our and all other topologically related materials and correlated these with empirical structural descriptors to derive general rules for trapping molecules in high-energy conformations within MOFs. These studies portend possible applications of MOFs for studying fundamental concepts related to conformational locking and its effects on molecular reactivity and chromophore photophysics.

  14. Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte.

    Science.gov (United States)

    Lowe, B M; Maekawa, Y; Shibuta, Y; Sakata, T; Skylaris, C-K; Green, N G

    2017-01-25

    Electronic devices are becoming increasingly used in chemical- and bio-sensing applications and therefore understanding the silica-electrolyte interface at the atomic scale is becoming increasingly important. For example, field-effect biosensors (BioFETs) operate by measuring perturbations in the electric field produced by the electrical double layer due to biomolecules binding on the surface. In this paper, explicit-solvent atomistic calculations of this electric field are presented and the structure and dynamics of the interface are investigated in different ionic strengths using molecular dynamics simulations. Novel results from simulation of the addition of DNA molecules and divalent ions are also presented, the latter of particular importance in both physiological solutions and biosensing experiments. The simulations demonstrated evidence of charge inversion, which is known to occur experimentally for divalent electrolyte systems. A strong interaction between ions and DNA phosphate groups was demonstrated in mixed electrolyte solutions, which are relevant to experimental observations of device sensitivity in the literature. The bound DNA resulted in local changes to the electric field at the surface; however, the spatial- and temporal-mean electric field showed no significant change. This result is explained by strong screening resulting from a combination of strongly polarised water and a compact layer of counterions around the DNA and silica surface. This work suggests that the saturation of the Stern layer is an important factor in determining BioFET response to increased salt concentration and provides novel insight into the interplay between ions and the EDL.

  15. The Sounds of Metal

    DEFF Research Database (Denmark)

    Grund, Cynthia M.

    2015-01-01

    Two, I propose that this framework allows for at least a theoretical distinction between the way in which extreme metal – e.g. black metal, doom metal, funeral doom metal, death metalrelates to its sound as music and the way in which much other music may be conceived of as being constituted...

  16. In situ and laboratory bioassays with Chironomus riparius larvae to assess toxicity of metal contamination in rivers: the relative toxic effect of sediment versus water contamination.

    Science.gov (United States)

    Faria, Mafalda S; Lopes, Ricardo J; Nogueira, António J A; Soares, Amadeu M V M

    2007-09-01

    We used bioassays employing head capsule width and body length increase of Chironomus riparius larvae as end points to evaluate metal contamination in streams. Bioassays were performed in situ near an abandoned Portuguese goldmine in the spring of 2003 and 2004. Bioassays also were performed under laboratory conditions with water and sediment collected from each stream to verify if laboratory bioassays could detect in situ toxicity and to evaluate the relative contribution of sediment and water to overall toxicity. We used field sediments with control water and control sediments with field water to discriminate between metal contamination in water and sediment. Field water with dry and sieved, organic matter-free, and nontreated sediments was used to determine the toxicity of heavy metals that enter the organism through ingested material. In both in situ and laboratory bioassays, body length increase was significantly inhibited by metal contamination, whereas head capsule width was not affected. Body length increase was more affected by contaminated sediment compared to contaminated water. The lowest-effect level of heavy metals was observed in the dry and sieved sediment that prevented ingestion of sediment particles by larvae. These results suggest that body length increase of C. riparius larvae can be used to indicate the impact of metal contamination in rivers. Chironomus riparius larvae are more affected by heavy metals that enter the organism through ingested sediment than by heavy metals dissolved in the water column. Nevertheless, several factors, such as the particle size and organic matter of sediment, must be taken into account.

  17. Plant-associated bacteria and their role in the success or failure of metal phytoextraction projects: first observations of a field-related experiment

    Science.gov (United States)

    Weyens, Nele; Beckers, Bram; Schellingen, Kerim; Ceulemans, Reinhart; Croes, Sarah; Janssen, Jolien; Haenen, Stefan; Witters, Nele; Vangronsveld, Jaco

    2013-01-01

    Phytoextraction has been reported as an economically and ecologically sound alternative for the remediation of metal-contaminated soils. Willow is a metal phytoextractor of interest because it allows to combine a gradual contaminant removal with production of biomass that can be valorized in different ways. In this work two willow clones growing on a metal-contaminated site were selected: ‘Belgisch Rood’ (BR) with a moderate metal extraction capacity and ‘Tora’ (TO) with a twice as high metal accumulation. All cultivable bacteria associated with both willow clones were isolated and identified using 16SrDNA ARDRA analysis followed by 16SrDNA sequencing. Further all isolated bacteria were investigated for characteristics that might promote plant growth (production of siderophores, organic acids and indol acetic acid) and for their metal resistance. The genotypic and phenotypic characterization of the isolated bacteria showed that the TO endophytic bacterial population is more diverse and contains a higher percentage of metal-resistant plant growth promoting bacteria than the endophytic population associated with BR. We hypothesize that the difference in the metal accumulation capacity between BR and TO clones might be at least partly related to differences in characteristics of their associated bacterial population. PMID:23425076

  18. One-step synthesis of gold bimetallic nanoparticles with various metal-compositions

    International Nuclear Information System (INIS)

    Bratescu, Maria Antoaneta; Takai, Osamu; Saito, Nagahiro

    2013-01-01

    Highlights: ► Synthesis of bimetallic nanoparticles in an aqueous solution discharge. ► Alloying gold with divalent sp metals, trivalent sp metals, 3d or 4d metals. ► Formation mechanism of bimetallic nanoparticles by metal reduction and gold erosion. ► Blue and red shift of surface plasmon resonance. -- Abstract: A rapid, one-step process for the synthesis of bimetallic nanoparticles by simultaneous metal reduction and gold erosion in an aqueous solution discharge was investigated. Gold bimetallic nanoparticles were obtained by alloying gold with various types of metals belonging to one of the following categories: divalent sp metals, trivalent sp metals, 3d or 4d metals. The composition of the various gold bimetallic nanoparticles obtained depends on electrochemical factors, charge transfer between gold and other metal, and initial concentration of metal in solution. Transmission electron microscopy and energy dispersive spectroscopy show that the gold bimetallic nanoparticles were of mixed pattern, with sizes of between 5 and 20 nm. A red-shift of the surface plasmon resonance band in the case of the bimetallic nanoparticles Au–Fe, Au–Ga, and Au–In, and a blue-shift of the plasmon band of the Au–Ag nanoparticles was observed. In addition, the interaction of gold bimetallic nanoparticles with unpaired electrons, provided by a stable free radical molecule, was highest for those NPs obtained by alloying gold with a 3d metal

  19. Heavy metals screening of rice bran oils and its relation to composition

    Science.gov (United States)

    Rice bran oil contains beneficial compounds that contribute to the high stability of the oil itself, as well as the health of consumers. As a result, rice bran oil has been growing in popularity and is now widely used in many countries. However, concerns have surfaced in recent years related to the ...

  20. Determination of the Relative Atomic Masses of Metals by Liberation of Molecular Hydrogen

    Science.gov (United States)

    Waghorne, W. Earle; Rous, Andrew J.

    2009-01-01

    Students determine the relative atomic masses of calcium, magnesium, and aluminum by reaction with hydrochloric acid and measurement of the volume of hydrogen gas liberated. The experiment demonstrates stoichiometry and illustrates clearly that mass of the reagent is not the determinant of the amounts in chemical reactions. The experiment is…

  1. Heavy Metal in Children's Tooth Enamel: Related to Autism and Disruptive Behaviors?

    Science.gov (United States)

    Abdullah, Maryam M.; Ly, Agnes R.; Goldberg, Wendy A.; Clarke-Stewart, K. Alison; Dudgeon, John V.; Mull, Christopher G.; Chan, Tony J.; Kent, Erin E.; Mason, Andrew Z.; Ericson, Jonathon E.

    2012-01-01

    To examine possible links between neurotoxicant exposure and neuropsychological disorders and child behavior, relative concentrations of lead, mercury, and manganese were examined in prenatal and postnatal enamel regions of deciduous teeth from children with Autism Spectrum Disorders (ASDs), high levels of disruptive behavior (HDB), and typically…

  2. Relative importance of different exposure routes of heavy metals for humans living near a municipal solid waste incinerator

    International Nuclear Information System (INIS)

    Li, Tong; Wan, Yi; Ben, Yujie; Fan, Senrong; Hu, Jianying

    2017-01-01

    The potential health effects of toxic chemicals (e.g. heavy metals) emitted by municipal solid waste incinerators (MSWIs) are of great concern to local residents, however there have been few studies on the contributions of different exposure pathways and their subsequent effects on the body burden of residents living near MSWIs. In this study, multiple exposure routes of heavy metals including Pb, Cr, Cd and Mn were assessed by investigating the metals in foods (such as vegetables, crops, meats and fruits etc.), drinking water, ambient air and soil collected surrounding an MSWI in Shenzhen, south China. Vegetable ingestion played the most important role in the total average daily dose of Pb and Cr, and cereals were the key exposure routes for Mn and Cd. Compound-specific contaminations were observed in the investigated areas, with Pb and Cr present in the surrounding environment, having accumulated to relatively high levels in the local vegetables, and the intake of contaminated vegetable foods greatly influencing the body burden of Pb and Cr. Consistently, significantly high blood concentrations of Pb and Cr were detected in the local residents compared to a referenced population, and a lack of significant differences was found for Cd and Mn. The results possibly suggested that emission of MSWI influenced the external exposure doses of the major pathways of Pb and Cr in this study, and resulted in the different body burden of metals in humans living near a MSWI. MSWI-local food-humans is an important exposure pathway for residents living near MSWI, and thus should not be neglected in developing future strategies and policies to prevent the high risks suffered by residents living near MSWIs. - Highlights: • Vegetable and cereal ingestion were the main contributors to exposure of Pb/Cr and Mn/Cd, respectively. • Concentrations of Pb/Cr in vegetables grown near MSWI were significantly higher. • Blood concentrations of Pb/Cr in populations near MSWI were

  3. Group 4 Metalloporphyrin diolato Complexes and Catalytic Application of Metalloporphyrins and Related Transition Metal Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Du, Guodong [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    -, bis-alkoxo, and chelating diolato complexes, depending on the identity of diols and the stoichiometry employed. It was also found that tin porphyrin complexes promoted the oxidative cleavage of vicinal diols and the oxidation of α-ketols to α-diketones with dioxygen. In extending the chemistry of metalloporphyrins and analogous complexes, a series of chiral tetraaza macrocyclic ligands and metal complexes were designed and synthesized. Examination of iron(II) complexes showed that they were efficient catalysts for the cyclopropanation of styrene by diazo reagents. Good yields and high diastereoselectivity were obtained with modest enantioselectivity. A rationalization of the stereoselectivity was presented on the basis of structural factors in a carbene intermediate.

  4. Bioaccumulation of heavy metals in the earthworms Lumbricus rubellus and Aporrectodea caliginosa in relation to total and available metal concentrations in field soils

    International Nuclear Information System (INIS)

    Hobbelen, P.H.F.; Koolhaas, J.E.; Gestel, C.A.M. van

    2006-01-01

    The aim of this study was to determine important metal pools for bioaccumulation by the earthworms Lumbricus rubellus and Aporrectodea caliginosa in soils with high binding capacity. Cd, Cu and Zn concentrations in soil, pore water and CaCl 2 extracts of soil, in leaves of the plant species Urtica dioica and in earthworms were determined at 15 field sites constituting a gradient in metal pollution. Variations in the Cu and Cd concentrations in L. rubellus and Cu concentrations in A. caliginosa were best explained by total soil concentrations, while variation in Cd concentration in A. caliginosa was best explained by pore water concentrations. Zn concentrations in L. rubellus and A. caliginosa were not significantly correlated to any determined variable. It is concluded that despite low availability, earthworms in floodplain soils contain elevated concentrations of Cu and Cd, suggesting that uptake takes place not only from the soluble metal concentrations. - Earthworms in floodplain soils not only accumulate heavy metals from soluble metal pools

  5. Bioaccumulation of heavy metals in the earthworms Lumbricus rubellus and Aporrectodea caliginosa in relation to total and available metal concentrations in field soils

    Energy Technology Data Exchange (ETDEWEB)

    Hobbelen, P.H.F. [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)]. E-mail: phobbelen@usgs.gov; Koolhaas, J.E. [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Gestel, C.A.M. van [Department of Animal Ecology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)

    2006-11-15

    The aim of this study was to determine important metal pools for bioaccumulation by the earthworms Lumbricus rubellus and Aporrectodea caliginosa in soils with high binding capacity. Cd, Cu and Zn concentrations in soil, pore water and CaCl{sub 2} extracts of soil, in leaves of the plant species Urtica dioica and in earthworms were determined at 15 field sites constituting a gradient in metal pollution. Variations in the Cu and Cd concentrations in L. rubellus and Cu concentrations in A. caliginosa were best explained by total soil concentrations, while variation in Cd concentration in A. caliginosa was best explained by pore water concentrations. Zn concentrations in L. rubellus and A. caliginosa were not significantly correlated to any determined variable. It is concluded that despite low availability, earthworms in floodplain soils contain elevated concentrations of Cu and Cd, suggesting that uptake takes place not only from the soluble metal concentrations. - Earthworms in floodplain soils not only accumulate heavy metals from soluble metal pools.

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

    Science.gov (United States)

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

    2016-02-01

    -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.

  7. Biosorption of divalent Pb, Cd and Zn on aragonite and calcite mollusk shells

    Energy Technology Data Exchange (ETDEWEB)

    Du Yang; Lian Fei [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Zhu Lingyan, E-mail: zhuly@nankai.edu.cn [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China)

    2011-07-15

    The potential of using mollusk shell powder in aragonite (razor clam shells, RCS) and calcite phase (oyster shells, OS) to remove Pb{sup 2+}, Cd{sup 2+} and Zn{sup 2+} from contaminated water was investigated. Both biogenic sorbents displayed very high sorption capacities for the three metals except for Cd on OS. XRD, SEM and XPS results demonstrated that surface precipitation leading to crystal growth took place during sorption. Calcite OS displayed a remarkably higher sorption capacity to Pb than aragonite RCS, while the opposite was observed for Cd. However, both sorbents displayed similar sorption capacities to Zn. These could be due to the different extent of matching in crystal lattice between the metal bearing precipitate and the substrates. The initial pH of the solution, sorbent's dosage and grain size affected the removal efficiency of the heavy meals significantly, while the organic matter in mollusk shells affected the removal efficiency to a lesser extent. - Highlights: > Mollusk shells display high removal efficiency to heavy metals in contaminated water. > Surface precipitation leading to crystal growth takes place during the sorption. > Crystal structure similarity between precipitates and substrates affects the sorption. > pH, sorbent dosage and grain size of adsorbent affects the removal efficiency. > Organic matter in mollusk shells affects the removal efficiency to a less extent. - Mollusk shells display high sorption ability to heavy metals and crystal structure similarity between precipitates and substrates affects the sorption.

  8. Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

    Science.gov (United States)

    Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

    2014-12-01

    Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Fabrication and metallization of 3D electrospun nanofiberous architecture with gold and silver coating for applications related to electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Park, Keon Young [University of Pennsylvania, 3451 Walnut Street, Philadelphia, PA 19104 (United States); Ramaraj, B. [Research and Development Department, Central Institute of Plastics Engineering and Technology (CIPET), 630, Phase IV, GIDC, Vatva, Ahmedabad 382445 (India); Choi, Won Suk [Department of Chemistry, Hannam University, 461-6 Jeon min-dong, Yuseoung-gu, Daejeon 305-811 (Korea, Republic of); Yoon, Kuk Ro, E-mail: kryoon@hannam.ac.kr [Department of Chemistry, Hannam University, 461-6 Jeon min-dong, Yuseoung-gu, Daejeon 305-811 (Korea, Republic of)

    2013-11-01

    We have engineered a metallic architecture with high surface area and ultralow density for applications related to electrochemical supercapacitors. This is achieved first by design and fabrication of new annular collector template for electrospinning process, then the extrusion of polystyrene (PS) nanofiber through the fabricated annulus collector template followed by electroless plating of nanofiber assembly with gold and silver. The resultant three dimensional structures were characterized by optical microscopy (OM), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The OM images suggest that the fabrication process causes the electrospun fibers to be hinged to one another, maximizing contact junctions enhancing mechanical stability. The coated structure has a superior surface area, is robust, and is freestanding – making it an attractive architectural design for an electrode. The SEM images show interlocking of nanofibers to one another, further indicating the potential application for this system as a high surface area, low density charge collector ideal for nanostructured growths. - Graphical abstract: A new annular collector template was designed and fabricated to create a 3D electrospun nanofiber assembly. This ultralight 3D architecture with high surface was electroless plated with silver and gold to assess its suitability for applications related to electrochemical supercapacitors. This structure is highly conductive leading us to believe that this product can be utilized as an alternate electrode charge collector. - Highlights: • A metallic architecture with high surface area and ultralow density was fabricated. • A new annular collector template for electrospinning was designed and fabricated. • Electrospun PS nanofibers with 3D structure were coated with silver and gold. • The coated structure is

  10. Molecular oxidative stress markers in olive ridley turtles (Lepidochelys olivacea) and their relation to metal concentrations in wild populations.

    Science.gov (United States)

    Cortés-Gómez, Adriana A; Morcillo, Patricia; Guardiola, Francisco A; Espinosa, Cristobal; Esteban, María A; Cuesta, Alberto; Girondot, Marc; Romero, Diego

    2018-02-01

    Due to their longevity and extensive migration areas, marine turtles are able to accumulate diverse contaminants over many years and as a consequence they represent an interesting bioindicator species for marine ecosystem pollution. Metals provoke toxicological effects in many aquatic animal species, but marine turtles have been under-investigated in this area. Thus, we have determined the presence of certain inorganic elements (As, Cd, Cu, Ni, Pb, Se and Zn) in olive ridley turtles (Lepidochelys olivacea) and related them to metallothionein (MT), superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) transcription and/or enzymatic activities. Gene expression of sod, cat and gr was found to be higher in blood than liver or kidney but most of the significant relationships were found in liver, not only for gene expression but also for enzyme activities. This must be related to the role the liver has as the first filter organ. Several positive relationships of sod, cat and gr gene expression in the different tissues were found in this population, as well as very high Cd concentrations. This could mean that these turtles are adapting to the metals-production of ROS and damage through a high transcription of these antioxidants. Multiple positive relationships with GR seem to be part of its compensatory effect due to the decrease of SOD production against the high and chronic exposure to certain xenobiotics. CAT, on the other hand, seems not to be used much, and glutathione detoxification of H 2 O 2 may be more important in this species. Finally, despite the very high Cd concentrations found in this population, no significant relationship was found in any tissue with metallothionein gene expression. These results, along with very high Cd concentrations and a negative relationship with Cu, lead us to consider some kind of disruption in mt gene expression in these turtles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Metallic stent implantation in patients with iliac artery occlusion: long-term patency rate and factors related to recurrence

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seok Kyun; Kim, Jae Kyu; Yoon, Woong; Kim, Jeong; Park, Jin Gyoon; Kang, Heoung Keun; Choi, Soo JinNa [Chonnam National University Hospital School of Medicine, Gwangju (Korea, Republic of)

    2003-09-01

    To determine the long-term patency rate in 68 patients with iliac artery occlusion who underwent metallic stent implantation, and to analyze the factors related to recurrence. Sixty-eight patients with occlusive disease of the iliac artery underwent implantation of a self-expandable metallic stent. The clinical symptoms were intermittent claudication (n=48), resting pain (n=11), and gangrene (n=9). Stent patency was determined by follow-up angiography and color Doppler imaging, and the cumulative patency rate using the Kaplan-Meier method. Cox's proportional hazard model was used to analyse recurrence-related factors involving clinical symptoms (Fontaine stage), risk factors, and anatomical factors such as lesion location, length, and the development of collaterals. The duration of follow-up varied from 1 day to 73 months (mean, 23.8 months). Arterial occlusion recurred in 16 of 68 patients (23.5%), and the cumulative patency rate was as follows: 95.4% at one month, 93.2% at six months, 80.1% at one year, 73.2% at two years, 68.9% at three years, and 62% at five years. According to a statistical analysis of risk factors, the recurrence (p=0.04) than in those without it, but in patients who smoked, hypertension, DM, and previous cerebrovascular disease were not statistically significant. With regard to anatomical factors, the recurrent rate for lesions involving the external iliac artery was 6.5 times higher (p=0.02) than for those involving the common iliac artery. Variations in the fontaine stage were not statistically significant indicators of recurrence. The recurrence rate after implantation of an iliac artery stent is higher in patients with heart disease than in those without it, and higher for occlusive lesions involving the external iliac artery than for those of the common iliac artery.

  12. Metallic stent implantation in patients with iliac artery occlusion: long-term patency rate and factors related to recurrence

    International Nuclear Information System (INIS)

    Chung, Seok Kyun; Kim, Jae Kyu; Yoon, Woong; Kim, Jeong; Park, Jin Gyoon; Kang, Heoung Keun; Choi, Soo JinNa

    2003-01-01

    To determine the long-term patency rate in 68 patients with iliac artery occlusion who underwent metallic stent implantation, and to analyze the factors related to recurrence. Sixty-eight patients with occlusive disease of the iliac artery underwent implantation of a self-expandable metallic stent. The clinical symptoms were intermittent claudication (n=48), resting pain (n=11), and gangrene (n=9). Stent patency was determined by follow-up angiography and color Doppler imaging, and the cumulative patency rate using the Kaplan-Meier method. Cox's proportional hazard model was used to analyse recurrence-related factors involving clinical symptoms (Fontaine stage), risk factors, and anatomical factors such as lesion location, length, and the development of collaterals. The duration of follow-up varied from 1 day to 73 months (mean, 23.8 months). Arterial occlusion recurred in 16 of 68 patients (23.5%), and the cumulative patency rate was as follows: 95.4% at one month, 93.2% at six months, 80.1% at one year, 73.2% at two years, 68.9% at three years, and 62% at five years. According to a statistical analysis of risk factors, the recurrence (p=0.04) than in those without it, but in patients who smoked, hypertension, DM, and previous cerebrovascular disease were not statistically significant. With regard to anatomical factors, the recurrent rate for lesions involving the external iliac artery was 6.5 times higher (p=0.02) than for those involving the common iliac artery. Variations in the fontaine stage were not statistically significant indicators of recurrence. The recurrence rate after implantation of an iliac artery stent is higher in patients with heart disease than in those without it, and higher for occlusive lesions involving the external iliac artery than for those of the common iliac artery

  13. Fabrication and metallization of 3D electrospun nanofiberous architecture with gold and silver coating for applications related to electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Park, Keon Young; Ramaraj, B.; Choi, Won Suk; Yoon, Kuk Ro

    2013-01-01

    We have engineered a metallic architecture with high surface area and ultralow density for applications related to electrochemical supercapacitors. This is achieved first by design and fabrication of new annular collector template for electrospinning process, then the extrusion of polystyrene (PS) nanofiber through the fabricated annulus collector template followed by electroless plating of nanofiber assembly with gold and silver. The resultant three dimensional structures were characterized by optical microscopy (OM), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The OM images suggest that the fabrication process causes the electrospun fibers to be hinged to one another, maximizing contact junctions enhancing mechanical stability. The coated structure has a superior surface area, is robust, and is freestanding – making it an attractive architectural design for an electrode. The SEM images show interlocking of nanofibers to one another, further indicating the potential application for this system as a high surface area, low density charge collector ideal for nanostructured growths. - Graphical abstract: A new annular collector template was designed and fabricated to create a 3D electrospun nanofiber assembly. This ultralight 3D architecture with high surface was electroless plated with silver and gold to assess its suitability for applications related to electrochemical supercapacitors. This structure is highly conductive leading us to believe that this product can be utilized as an alternate electrode charge collector. - Highlights: • A metallic architecture with high surface area and ultralow density was fabricated. • A new annular collector template for electrospinning was designed and fabricated. • Electrospun PS nanofibers with 3D structure were coated with silver and gold. • The coated structure is

  14. Structurally related hydrazone-based metal complexes with different antitumor activities variably induce apoptotic cell death.

    Science.gov (United States)

    Megger, Dominik A; Rosowski, Kristin; Radunsky, Christian; Kösters, Jutta; Sitek, Barbara; Müller, Jens

    2017-04-05

    Three new complexes bearing the tridentate hydrazone-based ligand 2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)pyridine (L) were synthesized and structurally characterized. Biological tests indicate that the Zn(ii) complex [ZnCl 2 (L)] is of low cytotoxicity against the hepatocellular carcinoma cell line HepG2. In contrast, the Cu(ii) and Mn(ii) complexes [CuCl 2 (L)] and [MnCl 2 (L)] are highly cytotoxic with EC 50 values of 1.25 ± 0.01 μM and 20 ± 1 μM, respectively. A quantitative proteome analysis reveals that treatment of the cells with the Cu(ii) complex leads to a significantly altered abundance of 102 apoptosis-related proteins, whereas 38 proteins were up- or down-regulated by the Mn(ii) complex. A closer inspection of those proteins regulated only by the Cu(ii) complex suggests that the superior cytotoxic activity of this complex is likely to be related to an initiation of the caspase-independent cell death (CICD). In addition, an increased generation of reactive oxygen species (ROS) and a strong up-regulation of proteins responsive to oxidative stress suggest that alterations of the cellular redox metabolism likely contribute to the cytotoxicity of the Cu(ii) complex.

  15. Structure of the oxalate-ATP complex with pyruvate kinase: ATP as a bridging ligand for the two divalent cations

    International Nuclear Information System (INIS)

    Lodato, D.T.; Reed, G.H.

    1987-01-01

    The 2 equiv of divalent cation that are required cofactors for pyruvate kinase reside in sites of different affinities for different species of cation. The intrinsic selectivity of the protein-based site for Mn(II) and of the nucleotide-based site for Mg(II) has been exploited in electron paramagnetic resonance (EOR) investigations of ligands for Mn(II) at the protein-based site. Oxalate, a structural analogue of the enolate of pyruvate, has been used as a surrogate for the reactive form of pyruvate in complexes with enzyme, Mn(II), Mg(II), and ATP. Superhyperfine coupling between the unpaired electron spin of Mn(II) and the nuclear spin of 17 O, specifically incorporated into oxalate, shows that oxalate is bound at the active site as a bidentate chelate with Mn(II). Coordination of the γ-phosphate of ATP to this same Mn(II) center is revealed by observation of superhyperfine coupling from 17 O regiospecifically incorporated into the γ-phosphate group of ATP. By contrast, 17 O in the α-phosphate or in the β-phosphate groups of ATP does not influence the spectrum. Experiments in 17 O-enriched water show that there is also a single water ligand bound to the Mn(II). These data indicate that ATP bridges Mn(II) and Mg(II) at the active site. A close spacing of the two divalent cations is also evident from the occurrence of magnetic interactions for complexes in which 2 equiv of Mn(II) are present at the active site. The structure for the enzyme-Mn(II)-oxalate-Mg(II)-ATP complex suggests a scheme for the normal reverse reaction of pyruvate kinase in which the divalent cation at the protein-based site activates the keto acid substrate through chelation and promotes phospho transfer by simultaneous coordination to the enolate oxygen and to a pendant oxygen from the γ-phosphate of ATP

  16. Relative SHG measurements of metal thin films: Gold, silver, aluminum, cobalt, chromium, germanium, nickel, antimony, titanium, titanium nitride, tungsten, zinc, silicon and indium tin oxide

    Directory of Open Access Journals (Sweden)

    Franklin Che

    Full Text Available We have experimentally measured the surface second-harmonic generation (SHG of sputtered gold, silver, aluminum, zinc, tungsten, copper, titanium, cobalt, nickel, chromium, germanium, antimony, titanium nitride, silicon and indium tin oxide thin films. The second-harmonic response was measured in reflection using a 150 fs p-polarized laser pulse at 1561 nm. We present a clear comparison of the SHG intensity of these films relative to each other. Our measured relative intensities compare favorably with the relative intensities of metals with published data. We also report for the first time to our knowledge the surface SHG intensity of tungsten and antimony relative to that of well known metallic thin films such as gold and silver. Keywords: Surface second-harmonic generation, Nonlinear optics, Metal thin films

  17. Relativity-Induced Bonding Pattern Change in Coinage Metal Dimers M2 (M = Cu, Ag, Au, Rg).

    Science.gov (United States)

    Li, Wan-Lu; Lu, Jun-Bo; Wang, Zhen-Ling; Hu, Han-Shi; Li, Jun

    2018-05-07

    The periodic table provides a fundamental protocol for qualitatively classifying and predicting chemical properties based on periodicity. While the periodic law of chemical elements had already been rationalized within the framework of the nonrelativistic description of chemistry with quantum mechanics, this law was later known to be affected significantly by relativity. We here report a systematic theoretical study on the chemical bonding pattern change in the coinage metal dimers (Cu 2 , Ag 2 , Au 2 , Rg 2 ) due to the relativistic effect on the superheavy elements. Unlike the lighter congeners basically demonstrating ns- ns bonding character and a 0 g + ground state, Rg 2 shows unique 6d-6d bonding induced by strong relativity. Because of relativistic spin-orbit (SO) coupling effect in Rg 2 , two nearly degenerate SO states, 0 g + and 2 u , exist as candidate of the ground state. This relativity-induced change of bonding mechanism gives rise to various unique alteration of chemical properties compared with the lighter dimers, including higher intrinsic bond energy, force constant, and nuclear shielding. Our work thus provides a rather simple but clear-cut example, where the chemical bonding picture is significantly changed by relativistic effect, demonstrating the modified periodic law in heavy-element chemistry.

  18. High-energy-density, aqueous, metal-polyiodide redox flow batteries

    Science.gov (United States)

    Li, Bin; Nie, Zimin; Wang, Wei; Liu, Jun; Sprenkle, Vincent L.

    2017-08-29

    Improved metal-based redox flow batteries (RFBs) can utilize a metal and a divalent cation of the metal (M.sup.2+) as an active redox couple for a first electrode and electrolyte, respectively, in a first half-cell. For example, the metal can be Zn. The RFBs can also utilize a second electrolyte having I.sup.-, anions of I.sub.x (for x.gtoreq.3), or both in an aqueous solution, wherein the I.sup.- and the anions of I.sub.x (for x.gtoreq.3) compose an active redox couple in a second half-cell.

  19. Photochemical process of divalent germanium responsible for photorefractive index change in GeO2-SiO2 glasses.

    Science.gov (United States)

    Sakoh, Akifumi; Takahashi, Masahide; Yoko, Toshinobu; Nishii, Junji; Nishiyama, Hiroaki; Miyamoto, Isamu

    2003-10-20

    The photoluminescence spectra of the divalent Ge (Ge2+) center in GeO2-SiO2 glasses with different photosensitivities were investigated by means of excitation-emission energy mapping. The ultraviolet light induced photorefractivity has been correlated with the local structure around the Ge2+ centers. The glasses with a larger photorefractivity tended to exhibit a greater band broadening of the singlet-singlet transition on the higher excitation energy side accompanied by an increase in the Stokes shifts. This strongly suggests the existence of highly photosensitive Ge2+ centers with higher excitation energies. It is also found that the introduction of a hydroxyl group or boron species in GeO2-SiO2 glasses under appropriate conditions modifies the local environment of Ge2+ leading to an enhanced photorefractivity.

  20. Crucial role of dynamic linker histone binding and divalent ions for DNA accessibility and gene regulation revealed by mesoscale modeling of oligonucleosomes

    Science.gov (United States)

    Collepardo-Guevara, Rosana; Schlick, Tamar

    2012-01-01

    Monte Carlo simulations of a mesoscale model of oligonucleosomes are analyzed to examine the role of dynamic-linker histone (LH) binding/unbinding in high monovalent salt with divalent ions, and to further interpret noted chromatin fiber softening by dynamic LH in monovalent salt conditions. We find that divalent ions produce a fiber stiffening effect that competes with, but does not overshadow, the dramatic softening triggered by dynamic-LH behavior. Indeed, we find that in typical in vivo conditions, dynamic-LH binding/unbinding reduces fiber stiffening dramatically (by a factor of almost 5, as measured by the elasticity modulus) compared with rigidly fixed LH, and also the force needed to initiate chromatin unfolding, making it consistent with those of molecular motors. Our data also show that, during unfolding, divalent ions together with LHs induce linker-DNA bending and DNA–DNA repulsion screening, which guarantee formation of heteromorphic superbeads-on-a-string structures that combine regions of loose and compact fiber independently of the characteristics of the LH–core bond. These structures might be important for gene regulation as they expose regions of the DNA selectively. Dynamic control of LH binding/unbinding, either globally or locally, in the presence of divalent ions, might constitute a mechanism for regulation of gene expression. PMID:22790986

  1. Amino propynyl benzoic acid building block in rigid spacers of divalent ligands binding to the Syk SH2 domains with equally high affinity as the natural ligand

    NARCIS (Netherlands)

    Dekker, Frank J; de Mol, Nico J; Fischer, Marcel J E; Liskamp, Rob M J; Dekker, Frank

    2003-01-01

    The construction of rigid spacers composed of amino propynyl benzoic acid building blocks is described. These spacers were used to link two phosphopeptide ligand sites towards obtaining divalent ligands with a high affinity for Syk tandem SH2 domains, which are important in signal transduction. The

  2. Iron encrustations on filamentous algae colonized by Gallionella-related bacteria in a metal-polluted freshwater stream

    Science.gov (United States)

    Mori, J. F.; Neu, T. R.; Lu, S.; Händel, M.; Totsche, K. U.; Küsel, K.

    2015-09-01

    Filamentous macroscopic algae were observed in slightly acidic to circumneutral (pH 5.9-6.5), metal-rich stream water that leaked out from a former uranium mining district (Ronneburg, Germany). These algae differed in color and morphology and were encrusted with Fe-deposits. To elucidate their potential interaction with Fe(II)-oxidizing bacteria (FeOB), we collected algal samples at three time points during summer 2013 and studied the algae-bacteria-mineral compositions via confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectra, and a 16S and 18S rRNA gene-based bacterial and algae community analysis. Surprisingly, sequencing analysis of 18S rRNA gene regions of green and brown algae revealed high homologies with the freshwater algae Tribonema (99.9-100 %). CLSM imaging indicated a loss of active chloroplasts in the algae cells, which may be responsible for the change in color in oxidation under the putative oxygen-saturated conditions that occur in association with photosynthetic algae. Quantitative PCR (polymerase chain reaction) revealed even higher Gallionella-related 16S rRNA gene copy numbers on the surface of green algae compared to the brown algae. The latter harbored a higher microbial diversity, including some putative predators of algae. A loss of chloroplasts in the brown algae could have led to lower photosynthetic activities and reduced EPS production, which is known to affect predator colonization. Collectively, our results suggest the coexistence of oxygen-generating algae Tribonema sp. and strictly microaerophilic neutrophilic FeOB in a heavy metal-rich environment.

  3. Modulation of Higher Order Chromatin Conformation in Mammalian Cell Nuclei Can Be Mediated by Polyamines and Divalent Cations.

    Directory of Open Access Journals (Sweden)

    Ashwat Visvanathan

    Full Text Available The organisation of the large volume of mammalian genomic DNA within cell nuclei requires mechanisms to regulate chromatin compaction involving the reversible formation of higher order structures. The compaction state of chromatin varies between interphase and mitosis and is also subject to rapid and reversible change upon ATP depletion/repletion. In this study we have investigated mechanisms that may be involved in promoting the hyper-condensation of chromatin when ATP levels are depleted by treating cells with sodium azide and 2-deoxyglucose. Chromatin conformation was analysed in both live and permeabilised HeLa cells using FLIM-FRET, high resolution fluorescence microscopy and by electron spectroscopic imaging microscopy. We show that chromatin compaction following ATP depletion is not caused by loss of transcription activity and that it can occur at a similar level in both interphase and mitotic cells. Analysis of both live and permeabilised HeLa cells shows that chromatin conformation within nuclei is strongly influenced by the levels of divalent cations, including calcium and magnesium. While ATP depletion results in an increase in the level of unbound calcium, chromatin condensation still occurs even in the presence of a calcium chelator. Chromatin compaction is shown to be strongly affected by small changes in the levels of polyamines, including spermine and spermidine. The data are consistent with a model in which the increased intracellular pool of polyamines and divalent cations, resulting from depletion of ATP, bind to DNA and contribute to the large scale hyper-compaction of chromatin by a charge neutralisation mechanism.

  4. Kinetics and thermodynamics of ceramic/metal interface reactions related to high T(sub c) superconducting applications

    Science.gov (United States)

    Notis, Michael R.; Oh, Min-Seok

    1990-01-01

    Superconducting ceramic materials, no matter what their form, size or shape, must eventually make contact with non-superconducting materials in order to accomplish current transfer to other parts of a real operating system, or for testing and measurement of properties. Thus, whether the configuration is a clad wire, a bulk superconducting disc, tape, or a thick or thin superconducting film on a substrate, the physical and mechanical behavior of interface (interconnections, joints, etc.) between superconductors and normal conductor materials of all kinds is of extreme importance to the technological development of these systems. Fabrication heat treatments associated with the particular joining process allow possible reactions between the superconducting ceramic and the contact to occur, and consequently influence properties at the interface region. The nature of these reactions is therefore of great broad interest, as these may be a primary determinant for the real capability of these materials. Research related both to fabrication of composite sheathed wire products, and the joining contacts for physical property measurements, as well as, a review of other related literature in the field are described. Comparison are made between 1-2-3, Bi-, and Tl-based ceramic superconductors joined to a variety of metals including Cu, Ni, Fe, Cr, Ag, Ag-Pd, Au, In, and Ga. The morphology of reaction products and the nature of interface degradation as a function of time will be highlighted.

  5. Assessment of the structural relations between the bcc and omega phases of Ti, Zr, Hf and other transition metals

    International Nuclear Information System (INIS)

    Aurelio, G.; Guillermet, A.F.

    2000-01-01

    The name omega (Ω) phase refers to a high-pressure structural modification of the transition metals (TMs) Ti, Zr, and Hf. In alloys of Ti, Zr and Hf with other TMs, the Ω phase can be formed and retained metastably at room temperature by quenching the bcc structure, which is usually the stable high-temperature phase in these alloy systems. As a part of a systematic investigation of the structural and bonding properties of the bcc and Ω phases, and of the bcc → Ω phase transformation in TMs and alloys, we present in this paper a detailed analysis of the structural relations between these phases in Ti, Zr, Hf and in other TMs. The approach is as follows. First, we establish the most general geometrical relations connecting the lattice parameters and interatomic distances (IDs) of the bcc and Ω structures. Next, we focus on the ratio between the relevant IDs of these phases, which are assessed on the basis of an extensive database with experimental and theoretical information. Both stable and metastable structures are considered, and various remarkable regularities in ID ratios are discussed. Finally, in the light of the systematics of ID ratios established in the present work, a discussion is made of the probable lattice parameters for the Ω phase of Hf, which are not yet accurately known from direct measurements. (orig.)

  6. Relations between stellar mass and electron temperature-based metallicity for star-forming galaxies in a wide mass range

    International Nuclear Information System (INIS)

    Shi Wei-Bin; Zhao Gang; Ruan Gui-Ping; Zhou Li; Liang Yan-Chun; Shao Xu; Liu Xiao-Wei; Hammer Francois; Flores Hector; Zhang Yong

    2014-01-01

    We select 947 star-forming galaxies from SDSS-DR7 with [O III]λ4363 emission lines detected at a signal-to-noise ratio larger than 5σ. Their electron temperatures and direct oxygen abundances are then determined. We compare the results from different methods. t 2 , the electron temperature in the low ionization region, estimated from t 3 , that in the high ionization region, is compared using three analysis relations between t 2 – t 3 . These show obvious differences, which result in some different ionic oxygen abundances. The results of t 3 , t 2 , O ++ /H + and O + /H + derived by using methods from IRAF and literature are also compared. The ionic abundances O ++ /H + are higher than O + /H + for most cases. The different oxygen abundances derived from T e and the strong-line ratios show a clear discrepancy, which is more obvious following increasing stellar mass and strong-line ratio R 23 . The sample of galaxies from SDSS with detected [O III]λ4363 have lower metallicites and higher star formation rates, so they may not be typical representatives of the whole population of galaxies. Adopting data objects from Andrews and Martini, Liang et al. and Lee et al. data, we derive new relations of stellar mass and metallicity for star-forming galaxies in a much wider stellar mass range: from 10 6 M ⊙ to 10 11 M ⊙ . (research papers)

  7. Interfacial (o/w) properties of naphthetic acids and metal naphthenates, naphtenic acid characterization and metal naphthenate inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Brandal, Oeystein

    2005-07-01

    Deposition of metal naphthenates in process facilities is becoming a huge problem for petroleum companies producing highly acidic crudes. In this thesis, the main focus has been towards the oil-water (o/w) interfacial properties of naphthenic acids and their ability to react with different divalent cations across the interface to form metal naphthenates. The pendant drop technique was utilized to determine dynamic interfacial tensions (IFT) between model oil containing naphthenic acid, synthetic as well as indigenous acid mixtures, and pH adjusted water upon addition of different divalent cations. Changes in IFT caused by the divalent cations were correlated to reaction mechanisms by considering two reaction steps with subsequent binding of acid monomers to the divalent cation. The results were discussed in light of degree of cation hydration and naphthenic acid conformation, which affect the interfacial conditions and thus the rate of formation of 2:1 complexes of acid and cations. Moreover, addition of non-ionic oil-soluble surfactants used as basis compounds in naphthenate inhibitors was found to hinder a completion of the reaction through interfacial dilution of the acid monomers. Formation and stability of metal naphthenate films at o/w interfaces were studied by means of Langmuir technique with a trough designed for liquid-liquid systems. The effects of different naphthenic acids, divalent cations, and pH of the subphase were investigated. The results were correlated to acid structure, cation hydration, and degree of dissociation, which all affect the film stability against compression. Naphthenic acids acquired from a metal naphthenate deposit were characterized by different spectroscopic techniques. The sample was found to consist of a narrow family of 4-protic naphthenic acids with molecular weights around 1230 g/mol. These acids were found to be very o/w interfacially active compared to normal crude acids, and to form Langmuir monolayers with stability

  8. Relations among pH, sulfate, and metals concentrations in anthracite and bituminous coal-mine discharges, Pennsylvania

    Science.gov (United States)

    Cravotta, III, Charles A.

    2006-01-01

    Water-quality data for discharges from 140 abandoned mines in the Bituminous and Anthracite Coalfields of Pennsylvania illustrate relations among pH, sulfate, and dissolved metal concentrations. The pH for the 140 samples ranged from 2.7 to 7.3, with two modes at pH 2.5 to 4 (acidic) and 6 to 7 (near neutral). Generally, flow rates were smaller and solute concentrations were greater for low-pH samples; flow rates increased with pH. Although the pH distribution was similar for the bituminous and anthracite subsets, the bituminous discharges had smaller median flow rates, greater concentrations of sulfate, iron, and aluminum, and smaller concentrations of barium and lead than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by alkaline ground water; (2) solubility control of aluminum, iron, manganese, barium, and lead by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous sulfate-complex formation. The formation of AlSO4+ and AlHSO4+2 complexes adds to the total dissolved aluminum concentration at pH of equilibrium with aluminum hydroxide or hydroxysulfate minerals and can account for 10 to 20 times greater concentrations of dissolved aluminum in bituminous discharges compared to anthracite discharges at similar pH. Sulfate complexation also can account for 10 to 30 times greater concentrations of dissolved ferric iron concentrations at equilibrium with ferrihydrite (Fe(OH)3) and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3 to 5. In contrast, lower barium and lead concentrations in bituminous than anthracite discharges indicates elevated sulfate concentration could decrease mobility of these metals by the formation of insoluble minerals such as barite (BaSO4) or anglesite (PbSO4). Most samples were saturated with barite, but none were saturated with anglesite. Hence, lead concentrations could be controlled by coprecipitation with

  9. Qualitative relation between heavy metal concentration in soil and agricultural products: a Chinese peri-urban case study

    Science.gov (United States)

    Kikuchi, Ryunosuke; Ferreira, Carla Sofia; Dinis Ferreira, Antonio

    2017-04-01

    A peri-urban area refers to a transition or interaction zone, where urban and rural activities are juxtaposed, and landscape features are subject to rapid modifications, mainly due to human activities. It is reported that peri-urban areas which might include valuable protected areas (e.g. forested hills, preserved woodlands, prime agricultural lands, etc.) can provide essential life support services for urban residents. A peri-urban area is not only a zone experiencing the immediate impacts of land demands from urban growth and pollution, but it is also a wider market-related zone of influence, recognized for the supply of agricultural and natural resource products. It is reported that China's environmental crisis is one of the most pressing challenges to emerge from the country's rapid industrialization; therefore a field study was carried out to investigate the qualitative relation of soil property with vegetable agricultural products in the Chinese peri-urban area located in Luoyang city (34°37'N and 112°27'E). Soil, water and plant (e.g. squash, Cucurbita maxima) samples were taken over the study site, and heavy metal concentrations were analyzed. All the soil samples showed Cd concentrations exceeded the permissible level established by Chinese guidelines for soil quality (0.3 mg/kg). The contents of Zn, Pb and Cu also surpassed the Chinese guideline levels (Zn = 250 mg/kg, Pb = 50 mg/kg and Cu = 100 mg/kg) in several soil samples. Although the sampled plants contained some degree of all the heavy metals, only the Al concentration was high in the Cucurbita maxima samples (317 mg/kg), which is a specie of cultivated squash. Considering the world market and the global trade of agricultural products, it can be said that the food risk associated with farm products containing Al is not local but global. It is concluded that an environmental contamination of the peri-urban areas may lead to the threat to food security.

  10. Topological evolution and photoluminescent properties of a series of divalent zinc-based metal–organic frameworks tuned via ancillary ligating spacers

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Xiao-Min; Zhao, Wen [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Zhao, Xiao-Li, E-mail: xlzhao@chem.ecnu.edu.cn [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China)

    2013-04-15

    The combination of divalent zinc ions, 4-(4-carboxybenzamido)benzoic acid and exo-bidendate bipyridine ligands gave rise to a series of new MOFs: [ZnL(bipy)]·DMF·H{sub 2}O (1), [ZnL(bpe)]·1.5H{sub 2}O (2), [ZnL(bpa)]·4H{sub 2}O (3) and [ZnL(bpp)]·1.75H{sub 2}O (4) (MOF=metal-organic framework, bipy=4,4′-bipyridine, bpe=trans-1,2-bis(4-pyridyl)ethylene, bpa=1,2-bis(4-pyridinyl)ethane, bpp=1,3-bis(4-pyridinyl)propane, H{sub 2}L=4,4′-(carbonylimino)dibenzoic acid). Fine tune over the topology of the MOFs was achieved via systematically varying the geometric length of the second ligating bipyridine ligands. Single-crystal X-ray analysis reveals that complex 1 has a triply interpenetrated three-dimensional (3D) framework with elongated primitive cubic topology, whereas isostructural complexes 2 and 3 each possesses a 6-fold interpenetrated diamondiod 3D framework. Further expansion of the length of the bipyridine ligand to bpp leads to the formation of 4, which features an interesting entangled architecture of 2D→3D parallel polycatenation. In addition, the thermogravimetric analyses and solid-state photoluminescent properties of the selected complexes are investigated. - Graphical abstract: The incorporation of exo-bidendate bipyridine spacers into the Zn–H{sub 2}L system has yielded a series of new MOFs exhibiting topological evolution from 3-fold interpenetration to 6-fold interpenetration and 2D→3D parallel polycatenation. Highlights: ► The effect of the pyridyl-based spacers on the formation of MOFs was explored. ► Fine tune over the topology of the MOFs was achieved. ► An interesting structure of 2D→3D parallel polycatenation is reported.

  11. Role of trace metals in cell proliferation in the human neuroblastoma: relations with the oncogene N-myc

    International Nuclear Information System (INIS)

    Moretto, Ph.; Michelet, C.; Gouget, B.; Ortega, R.; Sergiant, C.; Llabador, Y.; Simonoff, M.; Benard, J.

    1997-01-01

    Neuroblastoma is one of the most common tumors in young children. Iron is known to be necessary for cellular proliferation. Several studies have suggested that neuroblastoma cells appear to be relatively sensitive to growth inhibition by specific Fe chelators, in vitro. In addition, it appeared that an increased serum ferritin level at diagnosis was associated with a poorer outcome than a normal level. On the other hand it was reported that untreated primary neuroblastoma had multiple copies of the N-myc oncogene. A significant association between genomic amplification and rapid tumor progression after diagnosis has been demonstrated. In order to study the relationship between iron N-myc amplification, we propose to determine the trace metal content of neuroblastoma cells. Preliminary results obtained with two distinct cell lines: SK-N-SH, a neuroblastoma cell line with a single copy of N-myc and IGR-N-91, a metastatic cell line exhibiting 60 copies of N-myc are presented. (authors)

  12. Heavy Metal Removal by Chitosan and Chitosan Composite

    International Nuclear Information System (INIS)

    Abdel-Mohdy, F.A.; El-Sawy, S.; Ibrahim, M.S.

    2005-01-01

    Radiation grafting of diethyl aminoethyl methacrylate (DEAEMA) on chitosan to impart ion exchange properties and to be used for the separation of metal ions from waste water, was carried out. The effect of experimental conditions such as monomer concentration and the radiation dose on grafting were studied. On using chitosan, grafted chitosan and some chitosan composites in metal ion removal they show high up-take capacity for Cu 2+ and lower uptake capacities for the other divalent metal ions used (Zn and Co). Competitive study, performed with solutions containing mixture of metal salts, showed high selectivity for Cu 2+ than the other metal ion. Limited grafting of DEAEMA polymer -containing specific functional groups-onto the chitosan backbone improves the sorption performance

  13. Solid state cathode materials for secondary magnesium-ion batteries that are compatible with magnesium metal anodes in water-free electrolyte

    International Nuclear Information System (INIS)

    Crowe, Adam J.; Bartlett, Bart M.

    2016-01-01

    With high elemental abundance, large volumetric capacity, and dendrite-free metal deposition, magnesium metal anodes offer promise in beyond-lithium-ion batteries. However, the increased charge density associated with the divalent magnesium-ion (Mg 2+ ), relative to lithium-ion (Li + ) hinders the ion-insertion and extraction processes within many materials and structures known for lithium-ion cathodes. As a result, many recent investigations incorporate known amounts of water within the electrolyte to provide temporary solvation of the Mg 2+ , improving diffusion kinetics. Unfortunately with the addition of water, compatibility with magnesium metal anodes disappears due to forming an ion-insulating passivating layer. In this short review, recent advances in solid state cathode materials for rechargeable magnesium-ion batteries are highlighted, with a focus on cathode materials that do not require water contaminated electrolyte solutions for ion insertion and extraction processes. - Graphical abstract: In this short review, we present candidate materials for reversible Mg-battery cathodes that are compatible with magnesium metal in water-free electrolytes. The data suggest that soft, polarizable anions are required for reversible cycling.

  14. Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

    Energy Technology Data Exchange (ETDEWEB)

    Toutianoush, Ali [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); El-Hashani, Ashraf [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Schnepf, Judit [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany); Tieke, Bernd [Institut fuer Physikalische Chemie der Universitaet zu Koeln, Luxemburger Str. 116, D-50939 Cologne (Germany)]. E-mail: Tieke@Uni-Koeln.de

    2005-06-30

    Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors {alpha} (NaCl/MgCl{sub 2}) and {alpha} (NaCl/ZnCl{sub 2}) being 43 and 20. Rare earth metal chlorides LnCl{sub 3} with Ln being La, Ce, Pr and Sm and the related YCl{sub 3} were strongly rejected from the membrane, the theoretical separation factors {alpha} (NaCl/LaCl{sub 3}) and {alpha} (NaCl/YCl{sub 3}) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane.

  15. Multilayer membranes of p-sulfonato-calix[8]arene and polyvinylamine and their use for selective enrichment of rare earth metal ions

    International Nuclear Information System (INIS)

    Toutianoush, Ali; El-Hashani, Ashraf; Schnepf, Judit; Tieke, Bernd

    2005-01-01

    Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors α (NaCl/MgCl 2 ) and α (NaCl/ZnCl 2 ) being 43 and 20. Rare earth metal chlorides LnCl 3 with Ln being La, Ce, Pr and Sm and the related YCl 3 were strongly rejected from the membrane, the theoretical separation factors α (NaCl/LaCl 3 ) and α (NaCl/YCl 3 ) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane

  16. Effect of divalent impurities on some physical properties of LiF and NaF; Influence des impuretes divalentes sur quelques proprietes physiques du LiF et du NaF

    Energy Technology Data Exchange (ETDEWEB)

    Laj, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-05-01

    The ionic thermo-currents technique is applied to the study of impurity vacancy dipoles in LiF and NaF doped with several divalent cations. In LiF only one ITC band is observed whatever the impurity studied. In NaF on the contrary two ITC bands are present, one corresponding to the one observed in LiF, the other one, intense in the case of small impurities, at lower temperature. A parallel EPR study in the case of Mn{sup 2+} doped samples shows that the band observed in LiF and the corresponding one in NaF are due to the relaxation of dipoles formed by the association of an impurity and a vacancy in the next nearest position. The knowledge of the properties of the dipoles allows to show that the room temperature ionic conductivity of LiF is conditioned by the equilibrium: M{sup ++} {open_square}+ {yields} M{sup ++} + {open_square}+. It is also shown that the isolated cation vacancy originating from this dissociation is responsible for the enhancement of {gamma}-ray coloration of LiF doped with divalent cation impurities. A paramagnetic center ascribed to the presence of Mn{sup 0} isolated in the lattice is also studied. The value of the hyperfine interaction and its temperature dependence are in good agreement with both the theory and the other experimental results. Finally it is shown that the disappearance of dipoles by annealing is related to the formation of complexes involving OH{sup -} ions, probably of the M(OH){sub 2} type, with the two OH{sup -} ions occupying a single fluorine site. (author) [French] La technique des thermocourants ioniques est appliquee a l'etude des dipoles lacune-impurete dans LiF et NaF dopes avec plusieurs cations divalents. Dans LiF on met en evidence un seul pic de thermocourant quelle que soit l'impurete consideree. Dans NaF au contraire deux pics de thermocourants sont presents, l'un correspondant a celui observe dans LiF, l'autre, dominant dans le cas des impuretes de petite taille, a plus basse temperature. Une etude parallelle

  17. Effect of divalent impurities on some physical properties of LiF and NaF; Influence des impuretes divalentes sur quelques proprietes physiques du LiF et du NaF

    Energy Technology Data Exchange (ETDEWEB)

    Laj, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-05-01

    The ionic thermo-currents technique is applied to the study of impurity vacancy dipoles in LiF and NaF doped with several divalent cations. In LiF only one ITC band is observed whatever the impurity studied. In NaF on the contrary two ITC bands are present, one corresponding to the one observed in LiF, the other one, intense in the case of small impurities, at lower temperature. A parallel EPR study in the case of Mn{sup 2+} doped samples shows that the band observed in LiF and the corresponding one in NaF are due to the relaxation of dipoles formed by the association of an impurity and a vacancy in the next nearest position. The knowledge of the properties of the dipoles allows to show that the room temperature ionic conductivity of LiF is conditioned by the equilibrium: M{sup ++} {open_square}+ {yields} M{sup ++} + {open_square}+. It is also shown that the isolated cation vacancy originating from this dissociation is responsible for the enhancement of {gamma}-ray coloration of LiF doped with divalent cation impurities. A paramagnetic center ascribed to the presence of Mn{sup 0} isolated in the lattice is also studied. The value of the hyperfine interaction and its temperature dependence are in good agreement with both the theory and the other experimental results. Finally it is shown that the disappearance of dipoles by annealing is related to the formation of complexes involving OH{sup -} ions, probably of the M(OH){sub 2} type, with the two OH{sup -} ions occupying a single fluorine site. (author) [French] La technique des thermocourants ioniques est appliquee a l'etude des dipoles lacune-impurete dans LiF et NaF dopes avec plusieurs cations divalents. Dans LiF on met en evidence un seul pic de thermocourant quelle que soit l'impurete consideree. Dans NaF au contraire deux pics de thermocourants sont presents, l'un correspondant a celui observe dans LiF, l'autre, dominant dans le cas des impuretes de petite taille, a plus basse temperature

  18. Assessment of human health risk related to metals by the use of biomonitors in the province of Cordoba, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, Hebe A. [Departamento de Quimica, Instituto Multidisciplinario de Biologia Vegetal, IMBIV/CONICET-UNC, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 1611, Ciudad Universitaria, X5016GCA Cordoba (Argentina)], E-mail: hcarreras@com.uncor.edu; Wannaz, Eduardo D.; Pignata, Maria L. [Departamento de Quimica, Instituto Multidisciplinario de Biologia Vegetal, IMBIV/CONICET-UNC, Facultad de Ciencias Exactas, Fisicas y Naturales, Universidad Nacional de Cordoba, Av. Velez Sarsfield 1611, Ciudad Universitaria, X5016GCA Cordoba (Argentina)

    2009-01-15

    The evaluation of metal contents in the environment is of vital importance for the assessment of human exposure. Thus the species Usnea amblyoclada, Ramalina celastri and Tillandsia capillaris were tested as bioaccumulators of transition metals in the urban area of Cordoba city, Argentina. The level of metals on biomonitors was compared to that of total deposition samples. All three species discriminated zones within the urban area of Cordoba city with different pollution levels; they revealed high levels of Zn in the downtown area and confirmed high levels of some transition metals in an industrial area. The correlation analysis revealed that the lichen R. celastri had the highest correlation rates with total deposition samples, suggesting it is a valuable biomonitor of atmospheric pollution. A significant relationship was also observed between respiratory diseases in children and the contents of metal accumulated in R. celastri and T. capillaris, indicating their usefulness when assessing human exposure to metals. - Metal accumulation in epiphytes is correlated with human respiratory diseases.

  19. Assessment of human health risk related to metals by the use of biomonitors in the province of Cordoba, Argentina

    International Nuclear Information System (INIS)

    Carreras, Hebe A.; Wannaz, Eduardo D.; Pignata, Maria L.

    2009-01-01

    The evaluation of metal contents in the environment is of vital importance for the assessment of human exposure. Thus the species Usnea amblyoclada, Ramalina celastri and Tillandsia capillaris were tested as bioaccumulators of transition metals in the urban area of Cordoba city, Argentina. The level of metals on biomonitors was compared to that of total deposition samples. All three species discriminated zones within the urban area of Cordoba city with different pollution levels; they revealed high levels of Zn in the downtown area and confirmed high levels of some transition metals in an industrial area. The correlation analysis revealed that the lichen R. celastri had the highest correlation rates with total deposition samples, suggesting it is a valuable biomonitor of atmospheric pollution. A significant relationship was also observed between respiratory diseases in children and the contents of metal accumulated in R. celastri and T. capillaris, indicating their usefulness when assessing human exposure to metals. - Metal accumulation in epiphytes is correlated with human respiratory diseases

  20. Transition metal sulfide promoted molybdenum or tungsten sulfide catalysts and their uses for hydroprocessing

    International Nuclear Information System (INIS)

    Jacobson, A.J.; Chianelli, R.R.; Pecoraro, T.A.

    1987-01-01

    A process is described for hydrorefining a hydrocarbon feed which comprises contacting the feed at a temperature of at least about 150 0 C and in the presence of hydrogen with a catalyst obtained by heating one or more precursor salts at elevated temperature of at least about 150 0 C, in the presence of sulfur or one or more sulfur-bearing compounds and under oxygen-free conditions for a time sufficient to form the catalyst. The precursor salt contains a tetrathiometallate anion of Mo, W or mixture thereof and a cation comprising one or more divalent promoter metals which are chelated by at least one neutral, nitrogen-containing polydentate ligand. The divalent promoter metal is selected from the group consisting of Ni, Co, Zn, Cu and mixture thereof. The contacting occurs for a time sufficient to hydrorefine at least a portion of the feed

  1. Supported transition metal sulfide promoted molybdenum or tungsten sulfide catalysts and their uses for hydroprocessing

    International Nuclear Information System (INIS)

    Ho, T.C.; Chianelli, R.R.; Jacobson, A.J.; Young, A.R.

    1987-01-01

    A process is described for hydrotreating a hydrocarbon feed which comprises contacting the feed at a temperature of at least about 150 0 C and heating the composite at elevated temperature of at least about 150 0 C, in the presence of sulfur and under oxygen-free conditions for a time sufficient to form the catalyst. The precursor salt contains a tetrathiometallate anion of Mo, W or mixture thereof and a cation comprising one or more divalent promoter metals which are chelated by at least one neutral, nitrogen-containing polydentate ligand L. The divalent promoter metal is selected from the group consisting of Ni, Co, Zn, Cu and mixture thereof. The contacting occurs for a time sufficient to hydrotreat at least a portion of the feed

  2. Assessment of metal sorption mechanisms by aquatic macrophytes using PIXE analysis

    Energy Technology Data Exchange (ETDEWEB)

    Módenes, A.N., E-mail: anmodenes@yahoo.com.br [Department of Chemical Engineering-Postgraduate Program, West Parana State University, Campus of Toledo, rua da Faculdade 645, Jd. La Salle, 85903-000 Toledo, PR (Brazil); Espinoza-Quiñones, F.R.; Santos, G.H.F.; Borba, C.E. [Department of Chemical Engineering-Postgraduate Program, West Parana State University, Campus of Toledo, rua da Faculdade 645, Jd. La Salle, 85903-000 Toledo, PR (Brazil); Rizzutto, M.A. [Physics Institute, University of São Paulo, Rua do Matão s/n, Travessa R 187, 05508-900 São Paulo, SP (Brazil)

    2013-10-15

    Highlights: • Divalent metal ion removals by Egeria densa biosorbent. • Multielements concentrations in biosorbent samples by PIXE analysis. • Elements mass balance in liquid and solid phase before and after metal removals. • Assessment of the mechanisms involved in Cd{sup 2+} and Zn{sup 2+} removal by biosorbent. • Confirmation of the signature of ion exchange process in metal removal. -- Abstract: In this work, a study of the metal sorption mechanism by dead biomass has been performed. All batch metal biosorption experiments were performed using the aquatic macrophyte Egeria densa as biosorbent. Divalent cadmium and zinc solutions were used to assess the sorption mechanisms involved. Using a suitable equilibrium time of 2 h and a mixture of 300 mg biosorbent and 50 mL metal solution at pH 5, monocomponent sorption experiments were performed. In order to determine the residual amounts of metals in the aqueous solutions and the concentrations of removed metals in the dry biomass, Particle Induced X-ray Emission (PIXE) measurements in thin and thick target samples were carried out. Based on the strong experimental evidence from the mass balance among the major elements participating in the sorption processes, an ion exchange process was identified as the mechanism responsible for metal removal by the dry biomass.

  3. On the relation between the ratio of energy of vaporization to activation energy for flow and physical properties of liquid metals

    International Nuclear Information System (INIS)

    Dutt, N.V.K.; Ravikumar, Y.V.L.; Prasad, D.H.L.

    1993-01-01

    A relation between the ratio of energy of vaporization (Esub(vap) to the activation energy for flow (Esub(vis)) and the ratio of melting point (T m ) to the critical temperature (T c ) has been developed for liquid metals, and is shown to be superior to the examinations from Eyring theory. (author). 12 refs

  4. Heavy metal burden in coastal marine sediments of north west coast of India in relation to pollution

    Digital Repository Service at National Institute of Oceanography (India)

    Rokade, M.A.

    the concentrations of potentially toxic metals (Flegal and Wilhelmy, 1991; Hornberger et al., 1999). 6 Between 1850 and 1900 most of the Hg mining in the world occurred in the watershed of the San Francisco Bay. Hydraulic mining for gold mobilized sediments... to the ocean bottom water (about 0.2 8 μg/l). When anoxic diagenesis takes over, reduction of Fe also occurs with high levels of both the metals in pore waters. Several trace metals that are bound to particle surfaces are also mobilized with Mn and Fe...

  5. Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, Mohamed Magdy; Radalla, Abd-Elatty; Qasem, Fatma; Khaled, Rehab [Beni-Suef University, Beni-Suef (Egypt)

    2014-01-15

    Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu{sup 2+}, Ni{sup 2+}, Zn{sup 2+}, and Co{sup 2+} with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) .deg. C, and a constant ionic strength I=1x10{sup -1} mol L{sup -1} NaNO{sub 3} in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu{sup 2+}, Ni{sup 2+}, and Co{sup 2+} has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.

  6. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao; Croue, Jean-Philippe

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation

  7. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M., E-mail: luismiguel.varela@usc.es [Grupo de Nanomateriais e Materia Branda, Departamento de Física da Materia Condensada, Universidade de Santiago de Compostela, Campus Vida s/n, E-15782 Santiago de Compostela (Spain); Cabeza, Oscar [Facultade de Ciencias, Universidade da Coruña, Campus A Zapateira s/n, E-15008 A Coruña (Spain); Fedorov, Maxim [Department of Physics, Scottish University Physics Alliance (SUPA), University of Strathclyde, John Anderson Bldg., 107 Rottenrow East, Glasgow G4 0NG (United Kingdom); Lynden-Bell, Ruth M. [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2015-09-28

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF{sub 6}]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO{sub 3}]{sup −} and [PF{sub 6}]{sup −} anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca{sup 2

  8. Molecular dynamics simulations of the structure and single-particle dynamics of mixtures of divalent salts and ionic liquids

    International Nuclear Information System (INIS)

    Gómez-González, Víctor; Docampo-Álvarez, Borja; Gallego, Luis J.; Varela, Luis M.; Cabeza, Oscar; Fedorov, Maxim; Lynden-Bell, Ruth M.

    2015-01-01

    We report a molecular dynamics study of the structure and single-particle dynamics of mixtures of a protic (ethylammonium nitrate) and an aprotic (1-butyl-3-methylimidazolium hexaflurophosphate [BMIM][PF 6 ]) room-temperature ionic liquids doped with magnesium and calcium salts with a common anion at 298.15 K and 1 atm. The solvation of these divalent cations in dense ionic environments is analyzed by means of apparent molar volumes of the mixtures, radial distribution functions, and coordination numbers. For the protic mixtures, the effect of salt concentration on the network of hydrogen bonds is also considered. Moreover, single-particle dynamics of the salt cations is studied by means of their velocity autocorrelation functions and vibrational densities of states, explicitly analyzing the influence of salt concentration, and cation charge and mass on these magnitudes. The effect of the valency of the salt cation on these properties is considered comparing the results with those for the corresponding mixtures with lithium salts. We found that the main structural and dynamic features of the local solvation of divalent cations in ionic liquids are similar to those of monovalent salts, with cations being localized in the polar nanoregions of the bulk mixture coordinated in monodentate and bidentate coordination modes by the [NO 3 ] − and [PF 6 ] − anions. However, stronger electrostatic correlations of these polar nanoregions than in mixtures with salts with monovalent cations are found. The vibrational modes of the ionic liquid (IL) are seen to be scarcely affected by the addition of the salt, and the effect of mass and charge on the vibrational densities of states of the dissolved cations is reported. Cation mass is seen to exert a deeper influence than charge on the low-frequency vibrational spectra, giving a red shift of the vibrational modes and a virtual suppression of the higher energy vibrational modes for the heavier Ca 2+ cations. No qualitative

  9. The Role of Metal Binding in the Amyotrophic Lateral Sclerosis-Related Aggregation of Copper-Zinc Superoxide Dismutase

    Directory of Open Access Journals (Sweden)

    Ivana Sirangelo

    2017-08-01

    Full Text Available Protein misfolding and conformational changes are common hallmarks in many neurodegenerative diseases involving formation and deposition of toxic protein aggregates. Although many players are involved in the in vivo protein aggregation, physiological factors such as labile metal ions within the cellular environment are likely to play a key role. In this review, we elucidate the role of metal binding in the aggregation process of copper-zinc superoxide dismutase (SOD1 associated to amyotrophic lateral sclerosis (ALS. SOD1 is an extremely stable Cu-Zn metalloprotein in which metal binding is crucial for folding, enzymatic activity and maintenance of the native conformation. Indeed, demetalation in SOD1 is known to induce misfolding and aggregation in physiological conditions in vitro suggesting that metal binding could play a key role in the pathological aggregation of SOD1. In addition, this study includes recent advances on the role of aberrant metal coordination in promoting SOD1 aggregation, highlighting the influence of metal ion homeostasis in pathologic aggregation processes.

  10. A CRITICAL LOOK AT THE MASS-METALLICITY-STAR FORMATION RATE RELATION IN THE LOCAL UNIVERSE. I. AN IMPROVED ANALYSIS FRAMEWORK AND CONFOUNDING SYSTEMATICS

    Energy Technology Data Exchange (ETDEWEB)

    Salim, Samir; Salzer, John J. [Department of Astronomy, Indiana University, Bloomington, IN 47404 (United States); Lee, Janice C. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Ly, Chun [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Brinchmann, Jarle [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Davé, Romeel [University of the Western Cape, Bellville, Cape Town 7535 (South Africa); Dickinson, Mark [National Optical Astronomy Observatory, Tucson, AZ 85719 (United States); Charlot, Stéphane, E-mail: salims@indiana.edu [Institut d' Astrophysique de Paris, CNRS, F-75014 Paris (France)

    2014-12-20

    It has been proposed that the (stellar) mass-(gas) metallicity relation of galaxies exhibits a secondary dependence on star formation rate (SFR), and that the resulting M {sub *}-Z-SFR relation may be redshift-invariant, i.e., ''fundamental''. However, conflicting results on the character of the SFR dependence, and whether it exists, have been reported. To gain insight into the origins of the conflicting results, we (1) devise a non-parametric, astrophysically motivated analysis framework based on the offset from the star-forming ({sup m}ain{sup )} sequence at a given M {sub *} (relative specific SFR); (2) apply this methodology and perform a comprehensive re-analysis of the local M {sub *}-Z-SFR relation, based on SDSS, GALEX, and WISE data; and (3) study the impact of sample selection and of using different metallicity and SFR indicators. We show that metallicity is anti-correlated with specific SFR regardless of the indicators used. We do not find that the relation is spurious due to correlations arising from biased metallicity measurements or fiber aperture effects. We emphasize that the dependence is weak/absent for massive galaxies (log M {sub *} > 10.5), and that the overall scatter in the M {sub *}-Z-SFR relation does not greatly decrease from the M {sub *}-Z relation. We find that the dependence is stronger for the highest SSFR galaxies above the star-forming sequence. This two-mode behavior can be described with a broken linear fit in 12+log(O/H) versus log (SFR/M {sub *}), at a given M {sub *}. Previous parameterizations used for comparative analysis with higher redshift samples that do not account for the more detailed behavior of the local M {sub *}-Z-SFR relation may incorrectly lead to the conclusion that those samples follow a different relationship.

  11. Global DNA methylation in earthworms: A candidate biomarker of epigenetic risks related to the presence of metals/metalloids in terrestrial environments

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado Santoyo, Maria; Rodriguez Flores, Crescencio; Lopez Torres, Adolfo; Wrobel, Kazimierz [Department of Chemistry, University of Guanajuato, L de Retana No 5, 36000 Guanajuato (Mexico); Wrobel, Katarzyna, E-mail: katarzyn@quijote.ugto.mx [Department of Chemistry, University of Guanajuato, L de Retana No 5, 36000 Guanajuato (Mexico)

    2011-10-15

    In this work, possible relationships between global DNA methylation and metal/metalloid concentrations in earthworms have been explored. Direct correlation was observed between soil and tissue As, Se, Sb, Zn, Cu, Mn, Ag, Co, Hg, Pb (p < 0.05). Speciation results obtained for As and Hg hint at the capability of earthworms for conversion of inorganic element forms present in soil to methylated species. Inverse correlation was observed between the percentage of methylated DNA cytosines and total tissue As, As + Hg, As + Hg + Se + Sb ({beta} = -0.8456, p = 0.071; {beta} = -0.9406, p = 0.017; {beta} = -0.9526, p = 0.012 respectively), as well as inorganic As + Hg ({beta} = -0.8807, p = 0.049). It was concluded that earthworms would be particularly helpful as bioindicators of elements undergoing in vivo methylation and might also be used to assess the related risk of epigenetic changes in DNA methylation. - Graphical abstract: Display Omitted Highlights: > Several metals and metalloids contribute to epigenetic gene regulation. > As, Hg, Se, Sb inversely correlated with global DNA methylation in earthworms. > Biomethylation of the above elements in worms suggested. > Elements biomethylation apparently competes with DNA methylation. > DNA methylation a biomarker of epigenetic risks related to soil metals/metalloids. - Biomethylation of As, Hg in earthworms versus DNA methylation - a candidate biomarker of epigenetic risks related to the presence of metals/metalloids in soil.

  12. Theoretical studies on selectivity of dibenzo-18-crown-6-ether for alkaline earth divalent cations

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Jiyoung [Sangmyung Univ., Seoul (Korea, Republic of)

    2012-04-15

    Crown ether is one of well-known host molecules and able to selectively sequester metal cation. We employed M06-2X density functional theory with IEFPCM and SMD continuum solvation models to study selectivity of dibenzo-18-crown-6-ether (DB18C6) for alkaline earth dications, Ba{sup 2+}, Sr{sup 2+}, Ca{sup 2+}, and Mg{sup 2+} in the gas phase and in aqueous solution. Mg{sup 2+} showed predominantly strong binding affinity in the gas phase because of strong polarization of CO bonds by cation. In aqueous solution, binding free energy differences became smaller among these dications. However, Mg{sup 2+} had the best binding, being incompatible with experimental observations in aqueous solution. The enthalpies of the dication exchange reaction between DB18C6 and water cluster molecules were computed as another estimation of selectivity in aqueous solution. These results also demonstrated that Mg{sup 2+} bound to DB18C6 better than Ba{sup 2+}. We speculated that the species determining selectivity in water could be 2:1 complexes of two DB18C6s and one dication.

  13. Mechanistic studies related to the metal catalyzed reduction of carbon monoxide to hydrocarbons. Final report, April 1, 1977-June 30, 1985

    International Nuclear Information System (INIS)

    Casey, C.P.

    1985-02-01

    Studies of compounds related to proposed intermediates in the hydrogenation of carbon monoxide over homogeneous and heterogeneous catalysts have been carried out. The synthesis, structure, and reactions of metal formyl compounds have been investigated. The synthesis and desproportionation reactions of hydroxymethyl metal compounds have been explored. Reactions involving interconversion of n 5 - and n'-C 5 H 5 organometallic compounds have been discovered. New synthetic routes to bimetallic compounds with bridging hydrocarbon ligands have been developed. The first bimetallic compound with a budging CH ligand has been prepared. The hydrocarbation reaction in which the CH bond of a bridging methylidyne complex adds across a carbon-carbon double bond has been discovered. New heterobimetallic compounds linked by a heterodifunctional ligand and heterobimetallic compounds with directly bonded early and late transition metals have been synthesized in a search for new CO hydrogenation catalysts. 36 refs

  14. Concentrations of trace elements in human tissues and relation of ratios of mutual metals to the human health

    International Nuclear Information System (INIS)

    Ling-wei, X.; Shao-xian, L.; Xiao-juan, Z.

    1989-01-01

    According to the experimental results, the concentrations and concentrations in order, of trace elements in human tissues among Changsha's People in China are reported. The authors particularly present that the ratios of mutual metals (M/N) in normal physiological tissues and fluids are very important factors which indicate the metabolic situations of trace elements in the body and as the indices which evaluate the situation of human health. (M and N mean the concentrations of different trace elements in the tissues or fluids, respectively.) Up to now, it is still an interesting field to study the functions of trace elements for the human health. There are previously some reports about the concentrations of trace elements in normal physiological tissues/ or organs and fluids of human body. These provide very valuable data for biological medicine. In the study presented atomic absorption method was adopted in order to determine the concentrations of Zn, Cu, Mn, Ni, Pb and Cd in human tissues (liver, spleen, kidney, bone, lung, pancreas, heart and artery and muscle) at autopsy. The authors suggest that trace elements, are contained in the body in an aproportional way, in normal physiological tissues and fluids, and the ratios may directly indicate metabolic situation of trace elements in the body which further reveal the mystery of trace elements for human health. Therefore, the ratios M/N as an indicator of health is more proper than that only using concentrations of trace elements. Schroeder (1973) reported that incidence of heart disease is related to the imbalance of ration Zn/Cd and Zn/Cu rather than the concentrations of Zn, Cd, Cu, and the intellectual development also depends on the proper proportion among copper, cadmium, lead, zinc in the body

  15. Metal concentrations in Unio pictorum mancus (Mollusca, Lamellibranchia from of 12 Northern Italian lakes in relation to their trophic level

    Directory of Open Access Journals (Sweden)

    Paolo LODIGIANI

    2003-08-01

    Full Text Available This research aims to test the reliability of environmental monitoring by bioaccumulators of pollutants; that is to establish a positive relationship between the pollutant concentrations in the bioaccumulator and those in the water in which it lives. To this end we analysed the contents of Al, Cu, Zn, Fe, Mn and Ca in the soft tissues and shell of Unio pictorum mancus. The filtered water samples from the mussel habitat were analysed for the same metals. The mussels were collected from 15 stations settled in 12 Northern Italian lakes during the first two weeks of July 2001. These results were obtained: a metal concentrations varied widely with mussel size and among stations; b a significant positive correlation between the concentration of calcium in the water and in the mussel tissues, but no relationship emerged for the other metals; c no relationship between the metal concentrations in the tissues and those in the shell was found; d there was a certain tendency for Mn, Fe and Zn concentrations in the soft tissues to increase with shell size; e the sequence of the decreasing metal concentrations arranged for the tissues was similar to that of the shell, but rather different from that in the water; and f the concentration factor values of the trace metals were high for the shell and soft tissues. In highly productive lakes large size mussels dominated, whereas small mussels were more abundant in low productive lakes. Although the metal concentrations in the water of productive lakes were greater than in low productive ones, the metal concentrations in the tissues of the mussels from the latter were generally higher than those in the mussels from the former. We propose some hypotheses to explain this paradox. Finally, our results show that the metal concentrations in the mussels do not reflect the metal concentrations in the water in which they live. It follows that this commonly used but oversimplified monitoring system cannot be recommended. On

  16. Geochemical behavior and environmental risks related to the use of abandoned base-metal tailings as construction material in the upper-Moulouya district, Morocco.

    Science.gov (United States)

    Argane, R; El Adnani, M; Benzaazoua, M; Bouzahzah, H; Khalil, A; Hakkou, R; Taha, Y

    2016-01-01

    In some developing countries, base-metal residues that were abandoned in tailing ponds or impoundments are increasingly used as construction material without any control, engineering basis, or environmental concern. This uncontrolled reuse of mine tailings may constitute a new form of pollution risks for humans and ecosystems through metal leaching. Therefore, the aim of the current study is to assess mine drainage, metal mobility, and geochemical behavior of two abandoned mine tailings commonly used in the upper-Moulouya region (eastern Morocco) as fine aggregates for mortar preparation. Their detailed physical, chemical, and mineralogical properties were subsequently evaluated in the context of developing appropriate alternative reuses to replace their conventional disposal and limit their weathering exposure. The obtained results showed that both tailings contain relatively high quantities of residual metals and metalloids with lead (ranging between 3610 and 5940 mg/kg) being the major pollutant. However, the mineralogical investigations revealed the presence of abundant neutralizing minerals and low sulfide content which influence mine drainage geochemistry and subsequently lower metals mobility. In fact, leachate analyses from weathering cell kinetic tests showed neutral conditions and low sulfide oxidation rates. According to these results, the tailings used as construction material in the upper-Moulouya region have very low generating potential of contaminated effluents and their reuse as aggregates may constitute a sustainable alternative method for efficient tailing management.

  17. Heavy metal distributions in Peru Basin surface sediments in relation to historic, present and disturbed redox environments

    Science.gov (United States)

    Koschinsky, Andrea

    Heavy metal distributions in deep-sea surface sediments and pore water profiles from five areas in the Peru Basin were investigated with respect to the redox environment and diagenetic processes in these areas. The 10-20-cm-thick Mn oxide-rich and minor metal-rich top layer is underlain by an increase in dissolved Mn and Ni concentrations resulting from the reduction of the MnO 2 phase below the oxic zone. The mobilised associated metals like Co, Zn and Cu are partly immobilised by sorption on clay, organic or Fe compounds in the post-oxic environment. Enrichment of dissolved Cu, Zn, Ni, Co, Pb, Cd, Fe and V within the upper 1-5 cm of the oxic zone can be attributed to the degradation of organic matter. In a core from one area at around 22-25 cm depth, striking enrichments of these metals in dissolved and solid forms were observed. Offset distributions between oxygen penetration and Mn reduction and the thickness of the Mn oxide-rich layer indicate fluctuations of the Mn redox boundary on a short-term time scale. Within the objectives of the German ATESEPP research programme, the effect of an industrial impact such as manganese nodule mining on the heavy metal cycle in the surface sediment was considered. If the oxic surface were to be removed or disturbed, oxygen would penetrate deep into the formerly suboxic sediment and precipitate Mn 2+ and metals like Ni and Co which are preferably scavenged by MnO 2. The solid enrichments of Cd, V, and other metals formed in post-oxic environments would move downward with the new redox boundary until a new equilibrium between oxygen diffusion and consumption is reached.

  18. Ion exchange equilibrium for some uni-univalent and uni-divalent reaction systems using strongly basic anion exchange resin Duolite A-102 D

    Directory of Open Access Journals (Sweden)

    R.S. Lokhande

    2008-04-01

    Full Text Available The study on thermodynamics of ion exchange equilibrium for uni-univalent Cl-/I-, Cl-/Br-, and uni-divalent Cl-/SO42-, Cl-/C2O42- reaction systems was carried out using ion exchange resin Duolite A-102 D. The equilibrium constant K was calculated by taking into account the activity coefficient of ions both in solution as well as in the resin phase. The K values calculated for uni-univalent and uni-divalent anion exchange reaction systems was observed to increase with rise in temperature, indicating the endothermic exchange reactions having enthalpy values of 13.7, 38.0, 23.9, 22.9 kJ/mol, respectively.

  19. Modification of thermal sensitivity of Chinese hamster cells by exposure to solutions of monovalent and divalent cationic salts

    International Nuclear Information System (INIS)

    Raaphorst, G.P.; Azzam, E.I.; Vadasz, J.

    1984-06-01

    Chinese hamster V79 cells were heated in culture medium or in 0.155-mol.dm -3 solutions of LiCl, NaCl, KCl, MgCl 2 , CaCl 2 and BaCl 2 . The presence of any one of these ionic solutions during heating increased the thermal sensitivity of the cells. The order of increased thermal sensitivity was KCl > LiCl > NaCl for the monovalent salts and BaCl 2 > MgCl 2 > CaCl 2 for the divalent cation salts. The addition of glucose to LiCl or NaCl solutions did not reduce the thermal sensitization caused by these solutions. When cells were sensitized by LiCl or NaCl treatment, a change in pH from 7.2 to 6.6 did not further increase thermal sensitivity. These data show that nutrient and ionic factors and their interplay are involved in cellular thermal sensitivity

  20. Effect of divalent versus monovalent cations on the MS2 retention capacity of amino-functionalized ceramic filters.

    Science.gov (United States)

    Bartels, J; Hildebrand, N; Nawrocki, M; Kroll, S; Maas, M; Colombi Ciacchi, L; Rezwan, K

    2018-04-25

    Ceramic capillary membranes conditioned for virus filtration via functionalization with n-(3-trimethoxysilylpropyl)diethylenetriamine (TPDA) are analyzed with respect to their virus retention capacity when using feed solutions based on monovalent and divalent salts (NaCl, MgCl2). The log reduction value (LRV) by operating in dead-end mode using the model bacteriophage MS2 with a diameter of 25 nm and an IEP of 3.9 is as high as 9.6 when using feeds containing MgCl2. In contrast, a lesser LRV of 6.4 is observed for feed solutions based on NaCl. The TPDA functionalized surface is simulated at the atomistic scale using explicit-solvent molecular dynamics in the presence of either Na+ or Mg2+ ions. Computational prediction of the binding free energy reveals that the Mg2+ ions remain preferentially adsorbed at the surface, whereas Na+ ions form a weakly bound dissolved ionic layer. The charge shielding between surface and amino groups by the adsorbed Mg2+ ions leads to an upright orientation of the TPDA molecules as opposed to a more tilted orientation in the presence of Na+ ions. The resulting better accessibility of the TPDA molecules is very likely responsible for the enhanced virus retention capacity using a feed solution with Mg2+ ions.

  1. Inhibition of Na(+) -K+ pump activity by divalent cations in intact peritoneal mast cells of the rat

    DEFF Research Database (Denmark)

    Knudsen, T; Berthelsen, Carsten; Johansen, Torben

    1990-01-01

    1. The inhibition by the divalent cations magnesium, barium and strontium and the trivalent ion lanthanum of the Na(+) -K+ pump in the plasma membrane of rat peritoneal mast cells was studied in pure mast cell populations by measurement of the ouabain-sensitive uptake of the radioactive potassium...... or more, but no decrease was observed after 2 min incubation when the cells are supposed to be loaded with sodium due to the cell isolation procedure. 3. Barium and strontium caused concentration-dependent decreases in the ouabain-sensitive K(+) -(86Rb+) -uptake of the cells but the ouabain......-resistant uptake was not changed. Half maximum decrease in the ouabain-sensitive K+(86Rb+)-uptake was observed with 1.8 mM magnesium, 1.2mM barium and 0.7 mM strontium. 4. The trivalent ion lanthanum blocked almost completely the ouabain-sensitive K+(86Rb+)-uptake at a concentration of 1 microM as does 1 m...

  2. Relation between the electrolytic solution pressures of the metals and their toxicity to the stickleback (Gasterosteus acelueatus l. )

    Energy Technology Data Exchange (ETDEWEB)

    Jones, J R.E.

    1939-01-01

    Lethal concentration limits have been determined for the hydrogen ion and the ions of eighteen metals. The three-spined stickleback (Gasterosteus aculeatus l.) has been employed as test animal. According to their lethal concentration limits on a mg./l. basis their order of increasing toxicity is: Sr, Ca, Na, Ba, Mg, K, Mn, Co, Cr, Ni, Au, Zn, Cd, Pb, Al, Cu, H, Hg, and Ag. On a molar concentration basis the order is as follows: Na, Ca, Sr, Mg, Ba, K, Mn, Co, Cr, Ni, H, Zn, Al, Au, Cd, Pb, Cu, Hg, Ag. All these ions, with the exception of the first six (the metals of the alkalis and alkaline earths), bring about the death of fish by precipitating the gill secretions, thus causing asphyxiation. The alkali and alkaline earth metals appear to enter the body and act as true internal poisons. The position of iron is uncertain. The toxicity of solutions of iron salts appears to be due, mainly if not entirely, to their acidity. On a mg./l. or molar concentration basis there is a marked relationship between the toxicity of the metals and their solution pressures. The metals of very low solution pressure (Ag, Cu, etc.), i.e. those whose ions are most ready to part with their charges and enter into combination with other ions or compounds, are the most toxic as they precipitate the gill secretions and bring about asphyxiation with extreme rapidity. Metals of somewhat higher solution pressure (Zn, Pb, Cd) act in the same way but more slowly. Manganese, which of all the heavy metals has the highest solution pressure, takes effect very slowly and the ions of the alkali and alkaline earth metals, which have a high affinity for their charges, do not precipitate the gill secretions at all. In the case of all ions other than those of the alkali and alkaline earth metals the reactions responsible for the death of the fish take place outside the body. Thus their speed of action does not depend on their penetrating power and the permeability factor does not enter.

  3. Fermi Surface Properties of Eu-Divalent and Eu-Trivalent Electronic States with the AuCu3-type Cubic Structure

    International Nuclear Information System (INIS)

    Nakamura, Ai; Takeuchi, Tetsuya; Tatetsu, Yasutomi; Maehira, Takahiro; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika; Harima, Hisatomo

    2015-01-01

    The electronic states in EuBi 3 and EuPd 3 are known to be Eu-divalent and Eu- trivalent, respectively, from the previous studies using polycrystal samples. In the present study, we succeeded in growing high-quality single crystals, and carried out the de Haas-van Alphen (dHvA) measurements and energy band calculations to clarify the Fermi surface properties

  4. Divalent cations and the protein surface co-ordinate the intensity of human platelet adhesion and P-selectin surface expression.

    Science.gov (United States)

    Whiss, P A; Andersson, R G G

    2002-07-01

    At sites of blood vessel injury, platelets adhere to exposed vessel components, such as collagen, or immobilized fibrinogen derived from plasma or activated platelets. The divalent cations Mg(2+) and Ca(2+) are essential for platelet adhesion and activation, but Mg(2+) can also inhibit platelet activation. The present study evaluates, by an enzymatic method, the effects of various divalent cations on the adhesion of isolated human platelets to collagen, fibrinogen, albumin or plastic in vitro. By enzyme-linked immunosorbent assay, platelet surface expression of P-selectin was measured to estimate the state of activation on adherence. Mg(2+) increased platelet adhesion exclusively to collagen and fibrinogen at physiologically relevant concentrations. At higher concentrations, the adhesion declined. Ca(2+) induced a weak adhesion only to fibrinogen at physiological doses and a peak of increased adhesion to all protein-coated surfaces at 10 mmol/l. Mn(2+) elicited dose-dependent adhesion only to collagen and fibrinogen. Zn(2+), Ni(2+) and Cu(2+) increased the adhesion of platelets independently of the surface. Ca(2+) dose-dependently inhibited adhesion elicited by Mg(2+) to collagen and fibrinogen. No other combination of divalent cations elicited such an effect. Mg(2+)-dependent platelet adhesion to collagen and Ca(2+)-dependent adhesion to fibrinogen increased P-selectin expression. Thus, the present study shows that the outcome of the platelet adhesion depends on the surface and the access of divalent cations, which co-ordinate the intensity of platelet adhesion and P-selectin surface expression.

  5. Assessing ecotoxicity and uptake of metals and metalloids in relation to two different earthworm species (Eiseina hortensis and Lumbricus terrestris)

    International Nuclear Information System (INIS)

    Leveque, Thibaut; Capowiez, Yvan; Schreck, Eva; Mazzia, Christophe; Auffan, Mélanie; Foucault, Yann; Austruy, Annabelle; Dumat, Camille

    2013-01-01

    Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physico-chemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation. -- Highlights: •Historically polluted soils collected from a lead recycling facility were studied. •Cast production is a sensitive parameter to assess ecotoxicity on earthworms. •Both soil parameters, like organic matter content and pH and earthworm specie influence metal uptake and ecotoxicity. -- Behavioural factors and inorganic pollutant uptake by earthworms provide a valuable indication of bioavailability and ecotoxicity

  6. A guidance manual for estimating greenhouse gas emissions from fuel combustion and process-related sources for primary base metals smelting and refining

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-03-01

    This technical guidance manual is a useful resource for helping the metals industry compile inventories of its greenhouse gas (GHG) emissions. The guidance is consistent with Canada's national GHG accounting methodologies. It provides information to smelters and refiners of base metals on how to estimate their GHG emissions from fuel combustion and specific process-related activities. The base metals group in this manual included copper, nickel, lead, zinc, and cobalt. Fuel combustion includes all stationary combustion activities for generating heat or work, and includes waste incineration if the waste heat is used for energy. It also includes mobile fuel combustion activities such as on-site transportation of raw materials from one process to another. Guidance is provided for carbon dioxide (CO{sub 2}), methane (CH{sub 4}) and nitrous oxide (N{sub 2}O). Process-related activities include specific industrial processes that contribute to GHG emissions. For base metal smelting, this includes CO{sub 2} emissions from use of carbonate reagents, use of reducing agents, electrode consumption, and hydrofluorocarbons (HFC) emissions from use in refrigeration systems. This document also included sections on quality assurance; aspects of uncertainty assessment; verification; and, reporting of emissions information. refs., tabs., figs.

  7. Multisite Ion Model in Concentrated Solutions of Divalent Cations (MgCl2 and CaCl2): Osmotic Pressure Calculations

    Science.gov (United States)

    2015-01-01

    Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca2+ and Mg2+ ions. Saxena and Sept (J. Chem. Theor. Comput.2013, 9, 3538–3542) described a model, called the multisite-ion model, where instead of treating the ions as an isolated sphere, the charge was split into multiple sites with partial charge. This model provided accurate inner shell coordination of the ion with biomolecules and predicted better free energies for proteins and nucleic acids. Here, we expand and refine the multisite model to describe the behavior of divalent ions in concentrated MgCl2 and CaCl2 electrolyte solutions, eliminating the unusual ion–ion pairing and clustering of ions which occurred in the original model. We calibrate and improve the parameters of the multisite model by matching the osmotic pressure of concentrated solutions of MgCl2 to the experimental values and then use these parameters to test the behavior of CaCl2 solutions. We find that the concentrated solutions of both divalent ions exhibit the experimentally observed behavior with correct osmotic pressure, the presence of solvent separated ion pairs instead of direct ion pairs, and no aggregation of ions. The improved multisite model for (Mg2+ and Ca2+) can be used in classical simulations of biomolecules at physiologically relevant salt concentrations. PMID:25482831

  8. Metals in urine in relation to the prevalence of pre-diabetes, diabetes and atherosclerosis in rural India.

    Science.gov (United States)

    Velmurugan, Ganesan; Swaminathan, Krishnan; Veerasekar, Ganesh; Purnell, Jonathan Q; Mohanraj, Sundaresan; Dhivakar, Mani; Avula, Anil Kumar; Cherian, Mathew; Palaniswami, Nalla G; Alexander, Thomas; Pradeep, Thalappil

    2018-04-19

    Diabetes and cardiovascular diseases are growing burdens in rural communities worldwide. We have observed a high prevalence of diabetes among rural farming communities in India and sought to evaluate the association of non-traditional risk factors, such as metals, with diabetes and other cardiometabolic risk factors in this community. Anthropometric measurements, chemistries and carotid intima-media thickness were determined in 865 participants of the Kovai Medical Center and Hospital-Nallampatti Non-Communicable Disease Study-I (KMCH-NNCD-I, 2015), a cross-sectional study conducted in a farming village in South India. Urinary metal levels were determined by inductively couped plasma-mass spectrometry analysis and corrected to urinary creatinine level. Statistical analyses were performed to study the association between urinary metal levels and clinical parameters. 82.5% of the study population were involved in farming and high levels of toxic metals were detected in the synthetic fertilisers used in the study village. The prevalence of pre-diabetes, diabetes and atherosclerosis was 43.4%, 16.2% and 10.3%, respectively. On logistic regression analysis, no association of traditional risk factors such as body mass index, blood pressure and total cholesterol with disease conditions was observed, but urinary levels of metals such as arsenic, chromium, aluminium and zinc showed an association with diabetes, while arsenic and zinc showed an association with pre-diabetes and atherosclerosis. Our data suggest a probable role of metals in the aetiology of diabetes and cardiovascular diseases in rural communities. Identifying and eliminating the causes of increased levels of these environmental chemicals could have a beneficial impact on the burden of non-communicable diseases in rural population. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly

  9. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Fatigue life of metal treated by magnetic field

    Science.gov (United States)

    Liu, Zhao-Long; Hu, Hai-Yun; Fan, Tian-You; Xing, Xiu-San

    2009-03-01

    This paper investigates theoretically the influence of magnetization on fatigue life by using non-equilibrium statistical theory of fatigue fracture for metals. The fatigue microcrack growth rate is obtained from the dynamic equation of microcrack growth, where the influence of magnetization is described by an additional term in the potential energy of microcrack. The statistical value of fatigue life of metal under magnetic field is derived, which is expressed in terms of magnetic field and macrophysical as well as microphysical quantities. The fatigue life of AISI 4140 steel in static magnetic field from this theory is basically consistent with the experimental data.

  10. Evolution of the mass-metallicity relations in passive and star-forming galaxies from SPH-cosmological simulations

    DEFF Research Database (Denmark)

    Velonà, A. D Romeo; Sommer-Larsen, J.; Napolitano, N. R.

    2013-01-01

    at high redshift, whose scatter increases with time alongside the consolidation of the passive sequence. We also confirm the anti-correlation between sSFR and stellar mass, pointing at a key role of the former in determining the galaxy downsizing, as the most significant means of diagnostics of the star...... formation efficiency. Likewise, an anti-correlation between sSFR and metallicity can be established for the SF galaxies, while on the contrary more active galaxies in terms of simple SFR are also metal-richer. Finally, the [O/Fe] abundance ratio is presented too: we report a strong increasing evolution...

  11. Mobilisation of heavy metals into the urine by CaEDTA: relation to erythrocyte and plasma concentrations and exposure indicators.

    OpenAIRE

    Araki, S; Aono, H; Murata, K

    1986-01-01

    To investigate the effects of calcium disodium ethylenediamine tetra-acetate (CaEDTA) on the urinary excretion, erythrocyte, and plasma concentrations and exposure indicators of seven heavy metals, CaEDTA was administered by intravenous infusion to 20 workers exposed to lead, zinc, and copper. The workers' blood lead concentrations ranged from 22 to 59 micrograms/dl (mean 38 micrograms/dl (1.8 mumol/l]. The 24 hour urinary excretion of metals after CaEDTA administration (mobilisation yield) w...

  12. Zinc is the metal cofactor of Borrelia burgdorferi peptide deformylase.

    Science.gov (United States)

    Nguyen, Kiet T; Wu, Jen-Chieh; Boylan, Julie A; Gherardini, Frank C; Pei, Dehua

    2007-12-15

    Peptide deformylase (PDF, E.C. 3.5.1.88) catalyzes the removal of N-terminal formyl groups from nascent ribosome-synthesized polypeptides. PDF contains a catalytically essential divalent metal ion, which is tetrahedrally coordinated by three protein ligands (His, His, and Cys) and a water molecule. Previous studies revealed that the metal cofactor is a Fe2+ ion in Escherichia coli and many other bacterial PDFs. In this work, we found that PDFs from two iron-deficient bacteria, Borrelia burgdorferi and Lactobacillus plantarum, are stable and highly active under aerobic conditions. The native B. burgdorferi PDF (BbPDF) was purified 1200-fold and metal analysis revealed that it contains approximately 1.1 Zn2+ ion/polypeptide but no iron. Our studies suggest that PDF utilizes different metal ions in different organisms. These data have important implications in designing PDF inhibitors and should help address some of the unresolved issues regarding PDF structure and catalytic function.

  13. Surface energy and work function of elemental metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Rosengaard, N. M.

    1992-01-01

    and noble metals, as derived from the surface tension of liquid metals. In addition, they give work functions which agree with the limited experimental data obtained from single crystals to within 15%, and explain the smooth behavior of the experimental work functions of polycrystalline samples......We have performed an ab initio study of the surface energy and the work function for six close-packed surfaces of 40 elemental metals by means of a Green’s-function technique, based on the linear-muffin-tin-orbitals method within the tight-binding and atomic-sphere approximations. The results...... are in excellent agreement with a recent full-potential, all-electron, slab-supercell calculation of surface energies and work functions for the 4d metals. The present calculations explain the trend exhibited by the surface energies of the alkali, alkaline earth, divalent rare-earth, 3d, 4d, and 5d transition...

  14. Metal interactions with boron clusters

    International Nuclear Information System (INIS)

    Grimes, R.N.

    1982-01-01

    This book presents information on the following topics: the structural and bonding features of metallaboranes and metallacarboranes; transition-metal derivatives of nido-boranes and some related species; interactions of metal groups with the octahydrotriborate (1-) anion, B 3 H 8 ; metallaboron cage compounds of the main group metals; closo-carborane-metal complexes containing metal-carbon and metal-boron omega-bonds; electrochemistry of metallaboron cage compounds; and boron clusters with transition metal-hydrogen bonds

  15. Comparison of Structurally–Related Alkoxide, Amine, and Thiolate–Ligated MII (M= Fe, Co) Complexes: the Influence of Thiolates on the Properties of Biologically Relevant Metal Complexes

    Science.gov (United States)

    Brines, Lisa M.; Villar-Acevedo, Gloria; Kitagawa, Terutaka; Swartz, Rodney D.; Lugo-Mas, Priscilla; Kaminsky, Werner; Benedict, Jason B.; Kovacs, Julie A.

    2009-01-01

    Mechanistic pathways of metalloenzymes are controlled by the metal ion’s electronic and magnetic properties, which are tuned by the coordinated ligands. The functional advantage gained by incorporating cysteinates into the active site of non-heme iron enzymes such as superoxide reductase (SOR) is not entirely understood. Herein we compare the structural and redox properties of a series of structurally–related thiolate, alkoxide, and amine–ligated Fe(II) complexes in order to determine how the thiolate influences properties critical to function. Thiolates are shown to reduce metal ion Lewis acidity relative to alkoxides and amines, and have a strong trans influence thereby helping to maintain an open coordination site. Comparison of the redox potentials of the structurally analogous compounds described herein indicates that alkoxide ligands favor the higher-valent Fe3+ oxidation state, amine ligands favor the reduced Fe2+ oxidation state, and thiolates fall somewhere in between. These properties provide a functional advantange for substrate reducing enzymes in that they provide a site at the metal ion for substrate to bind, and a moderate potential that facilitates both substrate reduction, and regeneration of the catalytically active reduced state. Redox potentials for structurally–related Co(II) complexes are shown to be cathodically–shifted relative to their Fe(II) analogues, making them ineffective reducing agents for substrates such as superoxide. PMID:21731109

  16. A local leaky-box model for the local stellar surface density-gas surface density-gas phase metallicity relation

    Science.gov (United States)

    Zhu, Guangtun Ben; Barrera-Ballesteros, Jorge K.; Heckman, Timothy M.; Zakamska, Nadia L.; Sánchez, Sebastian F.; Yan, Renbin; Brinkmann, Jonathan

    2017-07-01

    We revisit the relation between the stellar surface density, the gas surface density and the gas-phase metallicity of typical disc galaxies in the local Universe with the SDSS-IV/MaNGA survey, using the star formation rate surface density as an indicator for the gas surface density. We show that these three local parameters form a tight relationship, confirming previous works (e.g. by the PINGS and CALIFA surveys), but with a larger sample. We present a new local leaky-box model, assuming star-formation history and chemical evolution is localized except for outflowing materials. We derive closed-form solutions for the evolution of stellar surface density, gas surface density and gas-phase metallicity, and show that these parameters form a tight relation independent of initial gas density and time. We show that, with canonical values of model parameters, this predicted relation match the observed one well. In addition, we briefly describe a pathway to improving the current semi-analytic models of galaxy formation by incorporating the local leaky-box model in the cosmological context, which can potentially explain simultaneously multiple properties of Milky Way-type disc galaxies, such as the size growth and the global stellar mass-gas metallicity relation.

  17. Anomalous Swelling in Wet-Spin Films of Divalent Calf-Thymus DNA

    Science.gov (United States)

    Marlowe, R. L.; Lee, S. A.; Rupprecht, A.

    2004-03-01

    The dimension of wet-spun oriented films of Ca- and MgDNA in the direction perpendicular to the helical axis has been measured using optical microscopy as a function of relative humidity (RH). Earlier work on monovalent DNA films found that the perpendicular dimension increases monotonically with RH. In contrast, both Ca - and MgDNA films display a 15% shrinkage in the perpendicular direction at about 93% RH and expand at higher values of RH.

  18. Study on the distribution and chemism of medium- and long-lived radionuclides in relation to corresponding microelements in the marine environment, algae and sediment on the Romanian cost. Part of a coordinated programme on marine radioactivity studies

    International Nuclear Information System (INIS)

    Georgescu, I.

    1976-09-01

    Comprehensive baseline data on various radionuclides as well as trace elements are presented for sea water, sediments and marine organisms collected from the Romanian coast of the Black Sea. Similar data are also presented for the samples collected along the Danube River. While no artificial radionuclide was found in the Black Sea water collected at 200m depth, where the anerobic condition prevails, the bottom sediment at the same station contained 137 Cs and other radionuclides. These results suggest that some precipitation process, most probably related to the occurrence of H 2 S, is taking place at this depth. The occurrence of divalent as well as trivalent iron in the bottom sediments proves possible reduction of various metals in this layer. In the Danube water some activation products such as 54 Mn, 60 Co, 65 Zn etc. were found in addition to the fission products radionuclides found normally in fallout. This finding may be related to the radioactive effluent release into the river

  19. Relation between the amount of dissolved water and metals dissolved from stainless steel or aluminum plate in safflower oil

    Energy Technology Data Exchange (ETDEWEB)

    Takasago, Masahisa; Takaoka, Kyo

    1986-12-01

    The amount of water dissolved in safflower oil at the frying temperature (180 deg C) was 518 -- 1012 ppM, allowing water to drop continuously (0.035 g/2 min) into the oil for 1 -- 3 h. When the oil was heated with metal plates under the same conditions, the amount of dissolved water in the oil increased more than in the absence of the metal plates. In case of stainless steel, the amount was 1.26 to 1.33 times, and with aluminum plates, 1.06 to 1.13 times the amount without plates. When these metal plates were heated with the oil under the above conditions, the water dissolved the metal of the plates into the oil. In case of stainless steel, iron dissolved from 0.17 to 0.77 ppM, nickel, 0.04 ppM and chromium, from 0.02 to 0.03 ppM. Similarly, the amount of aluminum dissolved from the aluminum plate was from 0.10 to 0.45 ppM.

  20. The relation between the amount of dissolved water and metals dissolved from stainless steel or aluminum plate in safflower oil

    International Nuclear Information System (INIS)

    Takasago, Masahisa; Takaoka, Kyo

    1986-01-01

    The amount of water dissolved in safflower oil at the frying temperature (180 deg C) was 518 ∼ 1012 ppm, allowing water to drop continuously (0.035 g/2 min) into the oil for 1 ∼ 3 h. When the oil was heated with metal plates under the same conditions, the amount of dissolved water in the oil increased more than in the absence of the metal plates. In case of stainless steel, the amount was 1.26 to 1.33 times, and with aluminum plates, 1.06 to 1.13 times the amount without plates. When these metal plates were heated with the oil under the above conditions, the water dissolved the metal of the plates into the oil. In case of stainless steel, iron dissolved from 0.17 to 0.77 ppm, nickel, 0.04 ppm and chromium, from 0.02 to 0.03 ppm. Similarly, the amount of aluminum dissolved from the aluminum plate was from 0.10 to 0.45 ppm. (author)

  1. Fate of Metals in Relation to Water and Sediment Properties in a Subtropical Lake in Central Himalaya, India.

    Science.gov (United States)

    Inaotombi, Shaikhom; Gupta, Prem Kumar

    2017-04-01

    Lakes of Himalaya are one of the most fragile ecosystems on earth. Tourism and urban development in the upland region strongly affect its water resources. The high rate of sedimentation and organic matter deposition alters the ecological state of sediment bed, which indirectly influences on dynamics of metallic elements. We investigated spatial and temporal variations of water and sediment characteristic in Lake Sattal of Central Himalaya, India. Samples were collected seasonally from four sampling locations from January 2011 to December 2012. Pearson's correlation and Canonical correspondence analysis (CCAs) were applied to examine the dynamics and behaviors of heavy metals. Concentrations of elements were in the order of fluoride (Fl) > zinc (Zn) > copper (Cu) > iron (Fe) > manganese (Mn). Sand size fraction was higher in the littoral zone while clay particle was dominant in the profundal zone of the lake. Dissolved oxygen at sediment-water-interface (SWI) and water temperature were the major factors influencing the dynamics of metallic contents in the water column. Spatially, total organic matter (TOM) was higher in the deeper portion of the lake. Our study revealed that mobility of Fe is temperature-dependent, whereas speciation of Mn and Cu are primarily controlled by the suboxic condition of SWI in organic-rich site. Upland lakes are more vulnerable to anoxic condition and have severe implications on heavy metals speciation. Proper implementation of land use policies and management practices, including stormwater detention, can be integrated into resolving such problems.

  2. Heavy metal accumulation related to population density in road dust samples taken from urban sites under different land uses

    NARCIS (Netherlands)

    Trujillo-González, Juan Manuel; Torres-Mora, Marco Aurelio; Keesstra, Saskia; Brevik, Eric C.; Jiménez-Ballesta, Raimundo

    2016-01-01

    Soil pollution is a key component of the land degradation process, but little is known about the impact of soil pollution on human health in the urban environment. The heavy metals Pb, Zn, Cu, Cr, Cd and Ni were analyzed by acid digestion (method EPA 3050B) and a total of 15 dust samples were

  3. Application of multivariate statistical analysis in the pollution and health risk of traffic-related heavy metals.

    Science.gov (United States)

    Ebqa'ai, Mohammad; Ibrahim, Bashar

    2017-12-01

    This study aims to analyse the heavy metal pollutants in Jeddah, the second largest city in the Gulf Cooperation Council with a population exceeding 3.5 million, and many vehicles. Ninety-eight street dust samples were collected seasonally from the six major roads as well as the Jeddah Beach, and subsequently digested using modified Leeds Public Analyst method. The heavy metals (Fe, Zn, Mn, Cu, Cd, and Pb) were extracted from the ash using methyl isobutyl ketone as solvent extraction and eventually analysed by atomic absorption spectroscopy. Multivariate statistical techniques, principal component analysis (PCA), and hierarchical cluster analysis were applied to these data. Heavy metal concentrations were ranked according to the following descending order: Fe > Zn > Mn > Cu > Pb > Cd. In order to study the pollution and health risk from these heavy metals as well as estimating their effect on the environment, pollution indices, integrated pollution index, enrichment factor, daily dose average, hazard quotient, and hazard index were all analysed. The PCA showed high levels of Zn, Fe, and Cd in Al Kurnish road, while these elements were consistently detected on King Abdulaziz and Al Madina roads. The study indicates that high levels of Zn and Pb pollution were recorded for major roads in Jeddah. Six out of seven roads had high pollution indices. This study is the first step towards further investigations into current health problems in Jeddah, such as anaemia and asthma.

  4. Assessing ecotoxicity and uptake of metals and metalloids in relation to two different earthworm species (Eiseina hortensis and Lumbricus terrestris).

    Science.gov (United States)

    Leveque, Thibaut; Capowiez, Yvan; Schreck, Eva; Mazzia, Christophe; Auffan, Mélanie; Foucault, Yann; Austruy, Annabelle; Dumat, Camille

    2013-08-01

    Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physico-chemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Determination of trace elements and heavy metals in agricultural products cultivated at the Rimac river valley in Lima city using nuclear and related analytical techniques

    OpenAIRE

    Bedregal, Patricia; Torres, Blanca; Olivera, Paula; Mendoza, Pablo; Ubillús, Marco; Creed-Kanashiro, H.; Penny, M.; Junco, J.; Ganoza, L.

    2004-01-01

    There are strong indications that the Rimac river valley is being contaminated with heavy metals and an excess of trace elements that come from some industrial and mining activities developed along the Rimac river valley. The agricultural products cultivated there in could be suffering the same effect. Nuclear and related analytical techniques will play an important role in the study of pollution by providing information concerning the degree of contamination in some agricultural products cul...

  6. Chemical evolution of the solar neighborhood. II. The age-metallicity relation and the history of star formation in the galactic disk

    International Nuclear Information System (INIS)

    Twarog, B.A.

    1980-01-01

    The age-metallicty relation for the disk in the neighborhood of the Sun is derived from four-color and Hβ photometry of a large sample of southern F dwarfs, analyzed in combination with theoretical isochrones. It is found that the mean metallicity of the disk increased by about a factor of 5 between 12 and 5 billion years ago and has increased only slightly since then; this conclusion is independent of the helium abundance assumed for the models

  7. Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations

    Science.gov (United States)

    Fabisch, Maria; Beulig, Felix; Akob, Denise M.; Küsel, Kirsten

    2013-01-01

    We identified and quantified abundant iron-oxidizing bacteria (FeOB) at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7), to moderately acidic (R2, pH 4.4), to slightly acidic (R3, pH 6.3) in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U) bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic “Ferrovum myxofaciens” was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and “Ferrovum myxofaciens” revealed that ~72% (R2 sediment) and 37% (R3 sediment) of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations of 35 mM Co, 24 mM Ni, and 1.3 mM Cd, higher than those in sediments. Our results will extend the limited knowledge of FeOB at contaminated, moderately to slightly acidic environments.

  8. Surprising abundance of Gallionella-related iron oxidizers in creek sediments at pH 4.4 or at high heavy metal concentrations

    Directory of Open Access Journals (Sweden)

    Maria eFabisch

    2013-12-01

    Full Text Available We identified and quantified abundant iron-oxidizing bacteria (FeOB at three iron-rich, metal-contaminated creek sites with increasing sediment pH from extremely acidic (R1, pH 2.7, to moderately acidic (R2, pH 4.4, to slightly acidic (R3, pH 6.3 in a former uranium-mining district. The geochemical parameters showed little variations over the 1.5 year study period. The highest metal concentrations found in creek sediments always coincided with the lowest metal concentrations in creek water at the slightly acidic site R3. Sequential extractions of R3 sediment revealed large portions of heavy metals (Ni, Cu, Zn, Pb, U bound to the iron oxide fraction. Light microscopy of glass slides exposed in creeks detected twisted stalks characteristic of microaerobic FeOB of the family Gallionellaceae at R3 but also at the acidic site R2. Sequences related to FeOB such as Gallionella ferruginea, Sideroxydans sp. CL21, Ferritrophicum radicicola, and Acidovorax sp. BrG1 were identified in the sediments. The highest fraction of clone sequences similar to the acidophilic ‘Ferrovum myxofaciens’ was detected in R1. Quantitative PCR using primer sets specific for Gallionella spp., Sideroxydans spp., and ‘Ferrovum myxofaciens’ revealed that approximately 72% (R2 sediment and 37% (R3 sediment of total bacterial 16S rRNA gene copies could be assigned to groups of FeOB with dominance of microaerobic Gallionella spp. at both sites. Gallionella spp. had similar and very high absolute and relative gene copy numbers in both sediment communities. Thus, Gallionella-like organisms appear to exhibit a greater acid and metal tolerance than shown before. Microaerobic FeOB from R3 creek sediment enriched in newly developed metal gradient tubes tolerated metal concentrations