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  • 1
    Digitale Medien
    Digitale Medien
    Hg2+-induced leakage of electrolytes and inhibition of NO3 − utilization inNostoc calcicola (1990)
    Springer
    BioMetals 3 (1990), S. 208-212 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Hg2+ toxicity ; Nostoc calcicola ; Electrolyte leakage ; NO3 − uptake ; Nitrate reductase ; Metal interactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary The effect of mercury (Hg2+) in the absence and presence of methylmercury (CH3Hg+), cadmium (Cd2+), copper (Cu2+), nickel (Ni2+) and calcium (Ca2+) on Nostoc calcicola Bréb. has been studied in terms of electrolyte leakage, NO3 − uptake and in vivo nitrate reductase (NR) activity to discover any possible correlation among such parameters under Hg2+ stress. Leakage of electrolytes from Hg2+-treated cyanobacterial cells was directly proportional to Hg2+ concentrations and exposure time. In comparison to NO3 − uptake, an about 60-fold slower rate of NR activity was observed in the untreated cultures, the former being five times more Hg2+-sensitive. A non-competitive synergistic interaction of Hg2+ with CH3Hg+ or Cd2+ and antagonistic with that of Ni2+ or Ca2+ has been observed for both the processes of NO3 − utilization. The antagonistic interaction of Cu2+ with Hg2+ in terms of NO3 − uptake and synergistic with respect to NR activity, has been attributed to the dual bonding preference of Cu2+ for cellular ligands. These findings suggest that (a) a statistically significant correlation exists among such parameters; (b) Hg2+ predominantly attacks the cyanobacterial cell membrane; (c) Hg2+ inhibits NO3 − utilization; (d) the presence of other cations increases or decreases the inhibitory actions of Hg2+.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01140581
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Assessment of Hg2+ toxicity to a N2-fixing cyanobacterium in long- and short-term experiments (1992)
    Springer
    BioMetals 5 (1992), S. 149-156 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Hg2+ toxicity ; cyanobacterium ; Nostoc calcicola ; growth ; photopigments ; nucleic acids ; photosynthesis ; membrane integrity ; nutrient uptake ; enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Toxicological responses of the filamentous N2-fixing cyanobacteriumNostoc calcicola Bréb. towards Hg2+ were studied to enumerate the decisive lethal events. In low-dose, long-term experiments (0.05–0.25 μm Hg2+, 10 days), photoautotrophic growth was severely inhibited with concurrent loss of photosynthetic pigments (phycocyanin〉chlorophyll α〉carotenoids) and nucleic acids. The termination of growth after a day 4 exposure to 0.25 μm Hg2+ has been attributed to the complete inhibition ofin vivo photosynthetic activity in the cyanobacterium (O2 evolution〉14CO2 incorporation). The elevated Hg2+ concentrations irreversibly damaged the cell membrance as observed under light microscopy, and as indicated by the leakage of intracellular electrolytes and phycocyanin. In high-dose, short-term experiments (0.5–20.0 μm Hg2+, up to 6 h), thein vivo activities of selected enzymes (glutamine synthetase 〉 nitrate reductase 〉 nitrogenase) were less inhibited by Hg2+ than the uptake of nutrient ions (NH 4 + 〉NO 3 − 〉PO 4 3− ).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01061321
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Methyl mercury uptake by free and immobilized cyanobacterium (1992)
    Springer
    BioMetals 5 (1992), S. 229-234 
    Details
    ISSN: 1572-8773
    Schlagwort(e): biofilm ; cell aging ; cyanobacterium foam ; immobilization ; Nostoc calcicola ; spheres
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Methyl mercury uptake in free cells and different immobilizates of the cyanobacteriumNostoc calcicola has been examined. The general growth of the immobilized cyanobacterial cells could be negatively correlated with methyl mercury uptake. Alginate spheres proved most efficient in terms of uptake rate (0.48 nmol mg protein−1 min−1, 10 min) and total bioaccumulation (10.71 nmol mg protein−1, 1 h) with a bioconcentration factor of 3.3×103. Alginate biofilms showed a faster methyl mercury accumulation rate (0.83 nmol mg protein−1 min−1, 10 min) with a saturation of 10.28 nmol mg protein−1 reached within only 30 min (bioconcentration factor, 3.1×103). Foam preparations with a slow initial uptake approximated biofilms but were characterized by a lower bioconcentration factor (2.8×103). Free cells, in comparison, maintained the initial slow rate of uptake (0.62 nmol mg protein−1 min−1, 10 min), saturating at 30 min (8.81 nmol mg protein−1), and the resultant lowest bioconcentration factor (2.7×103). Cell ageing (30 days) brought a drastic reduction (3-fold) in organomercury uptake by free cells while alginate spheres maintained the same potential. Foam preparations of the same age showed a significant improvement in methyl mercury uptake followed by only a marginal decline in alginate biofilms. Data are discussed in the light of the physiological efficiency and longevity of immobilized cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01061223
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Nutritional control of copper uptake in the cyanobacteriumNostoc calcicola Bréb (1991)
    Springer
    BioMetals 4 (1991), S. 192-196 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Cu uptake ; Starvations ; Recovery ; ATP ; Nostoc calcicola
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary The kinetics of Cu uptake in nutritionally starved cells of the diazotrophic cyanobacteriumNostoc calcicola Bréb. have been compared with those in cells recovering from starvation. Unstarved cyanobacterial cells assimilated 97.0 nmol Cu mg−1 protein within 1 h when incubated in medium containing 40 μM Cu. Uptake was markedly inhibited in carbon-starved cells and, to a lesser extent, in cells starved of nitrogen or sulphur. The intracellular concentrations of protein and photopigments were markedly lower in cells starved of carbon, nitrogen, sulphur or phosphorus, whilst that of carbohydrate was lower in cells starved of carbon, sulphur or phosphorus, but almost doubled in cells starved of nitrogen. The ability to assimilate Cu was partially restored in cells after 72 h of recovery from phosphorus or sulphur deprivation, but showed little improvement during recovery from carbon or nitrogen starvation. A possible role of phosphorus in regulating Cu transport and accumulation is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01141314
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Liquid exclusion chromatography. A technique for monitoring the growth of polymer particles in emulsion polymerization (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 22 (1978), S. 577-584 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An experimental investigation of the growth of polymer particles in the emulsion polymerization of styrene and of vinyl acetate is reported. The growth of polymer particles in the size range of 200-6500 Å was monitored by liquid exclusion chromatography (LEC). This relatively new analytical technique permits very rapid analysis for particles as small as 200 Å and should prove extremely useful as an online monitor of polymer particle size for the control of latex reactors.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1978.070220225
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Form Function for Propellants in Closed Vessel Work (1980)
    Weinheim : Wiley-Blackwell
    Propellants, Explosives, Pyrotechnics 5 (1980), S. 9-14 
    Details
    ISSN: 0721-3115
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A general theoretical cubic form function for use in closed vessel work during the evaluation of absolute ballistic parameters of propellants is introduced along with the expressions for the coefficients for a number of common propellant shapes. The conditions under which this form function is accurately applicable are also indicated. This form function is superior and gives much more accurate results than the quadratic form function which is in wide use at present. The differences of the cubic form function from the quadratic are also explained.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prep.19800050103
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Effect of zinc diisopropyl dithiophosphate on the photooxidative degradation of poly(2,6-dimethyl-1,4-phenylene oxide) films (1983)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 216-218 
    Details
    ISSN: 0323-7648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Der Einfluß von Zink-diisopropyl-dithiophosphat (ZnDTP) auf den photostabilisierten Abbau von Filmen aus Poly(2,6-dimethyl-1,4-phenylen-oxid) wurde im Konzentrationsbereich 0,1 bis 1,0 Masse-% untersucht. Der Abbau des Polymers hängt deutlich von der Konzentration des ZnDTP ab, das bei allen Konzentrationen als Photostabilisator wirkte.
    Notizen: The effect of zinc diisopropyl dithiophosphate (ZnDTP) chelate over the range of 0.1 to 1.0 wt.% on the photostabilized degradation of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) films was examined. The degradation of the polymer was remarkably affected by the concentration of the ZnDTP which acted as photostabilizer at all concentrations.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/actp.1983.010340407
    Standort Signatur Erwartet Verfügbarkeit
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