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  • superconductivity  (3)
  • Heavy metals  (2)
  • Recombinations  (2)
  • 1
    ISSN: 1432-0495
    Schlagwort(e): Key words Damodar River ; Heavy metals ; Grain size ; Chemical fractionation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract  The distribution of Si, Al, Fe, Mn, Cu, Zn, Ni and Cr in different grain-size fractions and geochemical association of Fe, Mn, Cu and Zn with 〈63-μm size fraction of bed sediments of Damodar River has been studied. In general, concentrations of heavy metals tend to increase as the size fractions get finer. However at two sites, near mining areas, the coarser particles show similar or even higher heavy metal concentrations than finer ones. The higher residence time and/or presence of coarser particles from mining wastes are possibly responsible for higher metal content in the coarser size fractions. The chemical fractionation study shows that lithogenic is the major chemical phase for heavy metals. Fe and Mn are the major elements of the lithogenic lattice, constituting 34–63% and 22–59%, respectively, of total concentrations. Fe-Mn oxide and organic bound fractions are significant phases in the non-lithogenic fraction. The carbonate fraction is less significant for heavy metal scavenging in the present environment and shows the following order of abundance Zn〉Cu〉Mn〉Fe. The exchangeable fraction of the Damodar sediments contains very low amounts of heavy metals suggesting poor bioavailability of metals.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 72 (1986), S. 164-169 
    ISSN: 1432-2242
    Schlagwort(e): Arachis ; Autotetraploid ; Chromosome pairing ; Genomic relationships ; Recombinations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Autotetraploids were established from 8 diploid wild species of section Arachis. In all the autotetraploids the chromosomes paired largely as bivalents even though they possess the ability to pair as multivalents. Pollen and pod fertility in the C1 generation were not directly associated with chromosome pairing. The C2 generation autotetraploids showed a gradual increase in bivalent associations and pollen and pod fertility. The identification of two genomes, A and B, in the diploid species and in the tetraploid, A. hypogaea, of the section Arachis, a fairly good crossability, and the type of chromosome associations observed in hybrids between A. hypogaea and the autotetraploids of wild Arachis species indicated good prospects of utilizing autotetraploids as genetic bridges in transferring desired traits from these taxa into groundnut.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 72 (1986), S. 433-439 
    ISSN: 1432-2242
    Schlagwort(e): Arachis ; Amphidiploids ; Genomes ; Chromosome pairing ; Recombinations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Synthetic amphidiploids were established in 32 combinations involving 8 diploid wild species representing both A and B genomes of section Arachis. Bivalent and multivalent associations in the amphidiploids of 7 A genome species confirm that these species have identical genomes. Contrastingly, high bivalent frequencies in amphidiploids involving the A and B genome species suggest that A. batizocoi has a distinct ‘B’ genome that is partially homologous to the other genome ‘A’ represented in the rest of the species. Crossability, chromosome pairing and pollen and pod fertility in hybrids between A. hypogaea and amphidiploids have revealed that these amphidiploids can be used as a genetic bridge for the transfer of genes from the wild species into the cultivated groundnut.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1572-8773
    Schlagwort(e): Heavy metals ; Efflux of Na+ and K+ ; Nostoc muscorum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary This study presents the effects of Cr, Pb, Ni and Ag on growth, pigments, protein, DNA, RNA, heterocyst frequency, uptake of NH4 + and N03 −, loss of electrolytes (Na+ and K+), nitrate reductase and glutamine synthetase activities ofNostoc muscorum. The statistical tests revealed a direct positive correlation between the metal concentration and inhibition of different processes. Ni was found to be more toxic against growth, pigments and heterocyst differentiation compared to the other metals. Inhibition of pigment showed the following trend: chlorophyll 〉 phycocyanin 〉 carotenoid. No generalized trend for inhibition of macromolecules was observed. The loss of K+ and Na+ as affected by Cr, Ni and Pb was similar but more pronounced for K+ than Na+. The inhibition of physiological variables depicted the following trend: Na+ loss 〉 K+ loss 〉 glutamine synthetase 〉 NH4 uptake 〉 growth 〉 N03 − uptake 〉 nitrate reductase 〉 heterocyst frequency. This study therefore suggests that loss of electrolytes can be used as a first signal of metal toxicity in cyanobacteria. However, further study is needed to confirm whether the abnormality induced by nickel (branch formation) is a physiological or genetic phenomenon.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1572-9605
    Schlagwort(e): ErBa2Cu3O7 ; superconductivity ; optical microscopy ; phase differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract The orthorhombic superconducting phase of YBa2Cu3O7 is shown to be differentiable from its tetragonal precursor by optical microscopy. Individual grains 1 μm in diameter or larger are found to either exhibit the color of the compensator in reflected polarized light (tetragonal material) or to change colors from the compensator (orthorhombic material). By using color differences, retained tetragonal material and the orthorhombic nature of untwinned areas of grains are identified. The advantage to producing better superconducting single crystals and sintered polycrystalline materials is discussed.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1572-9605
    Schlagwort(e): ErBa2Cu3O7 ; crystal growth ; microscopy ; superconductivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract Millimeter-sized crystals of ErBa2Cu3O7 were fortuitously grown while sintering a flat disk. It was possible to separate individual crystals from the sintered mass and measure their properties. The resistive transition and onset of magnetic transition of a single crystal was 93 K and the resistive transition width was 〈 1 K. Flux expulsion was observed and individual crystals could be levitated by a magnetic field. Crystals showed unusual growth features. They were heavily corrugated along the part of the crystal that grew parallel to the top surface of the disk and that coincided with thec axis of the unit cell. Crystals were characterized by X-rays, electron microscopy, and optical microscopy.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1572-9605
    Schlagwort(e): Cuprates ; superconductivity ; optical microscopy ; phase differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract A common mineralogical technique for identifying individual crystals in a heterogeneous, polycrystalline sample involves the observation at room temperature of their colors in reflected polarized light (colors of polarization). Here we present the observation that a brownish yellow (golden) color of polarization is not only characteristic of the YBa2Cu3O7 superconductor, but of the cuprate superconductors in general and is correlated with the occurrence of superconductivity.
    Materialart: Digitale Medien
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