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  • Chromatographie, Dünnschicht  (20)
  • Nitrogen fixation
  • Springer  (24)
  • American Chemical Society (ACS)
  • National Academy of Sciences
  • 1980-1984
  • 1975-1979  (24)
  • 1977  (24)
Collection
Keywords
Publisher
  • Springer  (24)
  • American Chemical Society (ACS)
  • National Academy of Sciences
Years
  • 1980-1984
  • 1975-1979  (24)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Nitrate effects on the nodulation of legumes inoculated with nitrate-reductase-deficient mutants of Rhizobium (1977)
    Springer
    Planta 134 (1977), S. 17-22 
    Details
    ISSN: 1432-2048
    Keywords: Leguminosae ; Nitrate-reductase mutants ; Nitrogen fixation ; Nodulation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of nitrate on the symbiotic properties of nitrate-reductase-deficient mutants of a strain of cowpea rhizobia (32H1), and of a strain of Rhizobium trifolii (TA1), were examined; the host species were Macroptilium atropurpureum (DC.) Urb. and Trifolium subterraneum L. Nitrate retarded initial nodulation by the mutant strains to an extent similar to that found with the parent strains. It is therefore unlikely that nitrite produced from nitrate by the rhizobia, plays a significant role in the inhibition of nodulation by nitrate. Nitrite is an inhibitor of nitrogenase, and its possible production in the nodule tissue by the action of nitrate reductase could be responsible for the observed inhibition of nitrogen fixation when nodulated plants are exposed to nitrate. However, the results of this investigation show that nitrogen fixation by the plants nodulated by parent or mutant strains was depressed by similar amounts in the presence of nitrate. No nitrite was detected in the nodules. Nodule growth, and to a lesser extent, the nitrogenase specific activity of the nodules (μmol C2H4g−1 nodule fr. wt. h−1), were both affected by the added nitrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390088
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a marine Anabaena sp. capable of rapid growth on molecular nitrogen (1977)
    Springer
    Archives of microbiology 114 (1977), S. 197-201 
    Details
    ISSN: 1432-072X
    Keywords: Anabaena sp. ; Nitrogen fixation ; Heterocysts ; Cyanobacteria ; Marine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A marine filamentous cyanobacterium capable of rapid growth under N2-fixing conditions has been isolated from the Texas Gulf Coast. This organism appears to be an Anabaena sp. and has been given the strain designation CA. Cultures grown on mineral salts medium bubbled with 1% CO2-enriched air at 42°C show a growth rate of 5.6±0.1 generations per day with molecular nitrogen as the sole nitrogen source. This growth rate is higher than any other reported in the literature to date for heterocystous cyanobacteria growing on N2. Under similar growth conditions, 7.5 mM NH4Cl yields a growth rate of 6.6±0.1 generations per day while 7.5 mM KNO3 allows for a growth rate of 5.8±0.4 generations-day. Nitrogen-fixation rates, as measured by acetylene reduction, show maximum activity values in the range of 50–100 nmoles ethylene produced/minxmg protein. These values compare favorably with those obtained from heterotrophic bacteria and are much higher than values reported for other cyanobacteria. Growth experiments indicate that the organism requires relatively high levels of sodium and grows maximally at 42°C. Because of its high growth rate on N2, this newly isolated organism appears ideal for studying nitrogen metabolism and heterocyst development among the cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446862
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  • 3
    Electronic Resource
    Electronic Resource
    The utilization of molecular hydrogen by the blue-green alga Anabaena cylindrica (1977)
    Springer
    Archives of microbiology 114 (1977), S. 43-49 
    Details
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Anabaena ; Hydrogenase ; Hydrogen-uptake ; Nitrogenase ; Nitrogen fixation ; Protection mechanism ; Inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The blue-green alga Anabaena cylindrica is found to consume molecular hydrogen in a hydrogenase dependent reaction. This hydrogen uptake proceeds in the dark and is strictly dependent on oxygen, thus representing a Knallgas reactions. Its rate is almost as high as that of the endogenous respiration in Anabaena. Studies with inhibitors reveal that hydrogen is utilized via the complete respiratory chain providing additional energy for the alga. CO plus C2H2 completely block the Knallgas reaction which explains the previously reported considerable increase in the total H2 formation representing the difference between the nitrogenase-dependent H2-evolution and the reutilization of the gas catalysed by the hydrogenase in intact Anabaena. H2 is able to support the C2H2-reduction in the dark in a reaction again strictly dependent on oxygen. Moreover, H2 is also consumed in experiments carried out under far red light and in the presence of dichlorophenyl-dimenthyl-urea (DCMU) where the energy for nitrogen fixation is no longer provided by respiration but by cyclic photophosphorylation. Under these conditions, H2 is found to supply electrons for the formation of C2H4 from C2H2 in a reaction no longer dependent on the presence of oxygen. Moreover, in these experiments, the presence of H2 stabilizes the C2H2-reduction activity against the deleterious effect of oxygen. Thus, this communication provides evidence for a triplicate function of the H2-uptake catalysed by hydrogenase in intact Anabaena which is (a) to provide energy by the Knallgas reaction, (b) to supply reducing equivalents for nitrogenase, (c) to protect nitrogenase from damage by oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429628
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of nutrient enrichment on nitrogen fixation activity in the Bay of Quinte, Lake Ontario (1977)
    Springer
    Hydrobiologia 56 (1977), S. 273-279 
    Details
    ISSN: 1573-5117
    Keywords: Nitrogen fixation ; nutrient enrichment ; limnocorral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogen fixation was measured in situ by the 15N tracer technique in the Bay of Quinte, Lake Ontario, and three lake enclosures with different nutrient enrichment. The fixation rates in the Bay were low but detectable during the summer season. The fixation activities were found to be correlated with the presence of nitrogen-fixing blue-green algae and the distribution of the algal species in the water was affected by nitrate enrichment. The study showed that, with the addition of nitrate, species not able to fix atmospheric nitrogen became predominant. However, in the absence of external nitrogen (i.e., nitrate), species able to fix nitrogen became dominant. Phosphorus enrichment alone did result in higher N-fixation rates in the water and, without the addition of phosphorus, the fixation rates are lower and fluctuate throughout the season, presumably dependent on the availability of phosphorus in the water. A comparison between the 15N-isotopic method and the acetylene reduction method is reported and the factors involved in the variations between these two methods are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017515
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  • 5
    Electronic Resource
    Electronic Resource
    Identification of LSD and ergot alkaloids by thin-layer chromatography (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 283 (1977), S. 32-32 
    Details
    ISSN: 1618-2650
    Keywords: Nachw. von LSD, Ergot-Alkaloiden ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00439765
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  • 6
    Electronic Resource
    Electronic Resource
    Thin-layer chromatography of some ergot alkaloids (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 284 (1977), S. 47-48 
    Details
    ISSN: 1618-2650
    Keywords: Analyse von Ergotalkaloiden ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464041
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  • 7
    Electronic Resource
    Electronic Resource
    Detection and determination of dichlorovos (DDVP) in toxicological analysis (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 285 (1977), S. 48-48 
    Details
    ISSN: 1618-2650
    Keywords: Nachw., Best. von Dichlorvos in Biolog. Material ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00446021
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  • 8
    Electronic Resource
    Electronic Resource
    Thin-layer chromatographic separation of some isomeric thiazolylbenzothiazoles (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 285 (1977), S. 255-255 
    Details
    ISSN: 1618-2650
    Keywords: Trenn. von Thiazolylbenzothiazolen ; Chromatographie, Dünnschicht ; isomere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00453575
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  • 9
    Electronic Resource
    Electronic Resource
    Über chromatographische Trennungen der Seltenen Erden (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 286 (1977), S. 50-53 
    Details
    ISSN: 1618-2650
    Keywords: Trenn, von Seltenen Erden ; Chromatographie, Dünnschicht ; Verteilungsverfahren ; Tetrahydrofuran, Triphenylphosphinoxid, Paraldehyd, Di-iso-propyläther-Tetrahydrofuran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Verteilungskonstanten von Selten-Erd-Nitraten im System Tributylphosphat-wäßrige Nitrat-Lösung werden berechnet. Dünnschicht-chromatographisch können mit Tributylphosphat in Isooctan als Laufmittel die Selten-Erd-Nitrate von La bis Gd vom Gd bis Lu getrennt werden. Eine Trennung von 13 Seltenen Erden auf einem Chromatogramm gelingt mit den Laufmitteln a) Tetrahydrofuran/Paraldehyd/Salpetersäure (20∶70∶10), b) dem Laufmittel Triphenylphosphinoxid (0,3 M in Paraldehyd) und konz. Salpetersäure im Verhältnis 90∶10, c) Di-iso-propyläther/Tetrahydrofuran/Salpetersäure (100 ∶ 60 ∶ 10). Der Trennmechanismus wird diskutiert.
    Notes: Abstract The distribution constants of the rare earth nitrates in the system tri-n-butylphosphate/aqueous nitrate solution are calculated. With thin-layer chromatography it is possible to separate the rare earth nitrates from La to Gd and from Gd to Lu in the solvent system tri-n-butylphosphate in i-octane. A separation of 13 rare earths in only one chromatogram is possible in the solvent systems a) tetrahydrofuran/paraldehyde/nitric acid (20∶70∶10), b) tri-phenylphosphinoxide (0.3 M in paraldehyde)/conc. nitric acid in the ratio 90∶10, c) di-iso-propylether/tetrahydrofuran/nitric acid (100∶60∶10). The mechanism of the separation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00552348
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  • 10
    Electronic Resource
    Electronic Resource
    Steuergerät zur automatischen spektralphotometrischen Direktauswertung von Dünnschicht-Chromatogrammen (1977)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 285 (1977), S. 111-120 
    Details
    ISSN: 1618-2650
    Keywords: Chromatographie, Dünnschicht ; Steuergerät zur automatischen Registrierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein Gerät zur vollautomatischen Steuerung eines DC-Spektralphotometers wurde entwickelt. Zusätzlich zur automatischen Registrierung aller Spuren eines Dünnschicht-Chromatogramms werden Remissionsminima erkannt und ihre Remissionsgrade und Ortskoordinaten ausgedruckt. Eine zweite Betriebsart ermöglicht ein manuelles Abrastern und Ausmessen eines Fleckes an jeder beliebigen Stelle der DC-Platte. Ein Rechneranschluß zur Auswertung der Meßergebnisse ist vorhanden. An Hand von Beispielen wird gezeigt, daß Reproduzierbarkeits- und Konzentrationsfehler bei der automatischen Registrierung strichförmiger Flecke wesentlich kleiner sind als bei Handpositionierung kreisförmiger Flecke. Die Linearität verschiedener Analysenfunktionen wird über 2 Zehnerpotenzen der Strichbelegung untersucht. Dabei erweist sich die Kubelka-Munk-Funktion in bezug auf Linearität allen anderen untersuchten Funktionen überlegen. Eine Kosten-Nutzen-Rechnung zeigt, daß in einem Routinelabor durch Einsatz eines Auftragegerätes und eines Steuergerätes für die automatische Registrierung trotz höherer Investitionskosten die Gesamtkosten einer Analyse um 70% gesenkt werden können.
    Notes: Abstract An instrument has been constructed for the automatic control of a TLC spectrophotometer. In addition to the automatic scanning of all tracks of a thin-layer chromatogram the positions and values of diffuse reflectance minima are recognized and printed. A second mode allows the manual scanning and measurement of a spot at any position on the TLC plate. A digital output is provided for the evaluation of the results with a computer. The errors of reproducibility and of concentration are much smaller using the automatic scanning of bands than using the manual positioning of circular spots as the examples show. The linearity of several analytical functions is analysed within two decades of concentration. The Kubelka-Munk function was found to be superior in linearity to all other functions studied. Calculations of costs show, that the total costs of an analysis in a routine laboratory can be lowered to an extend of about 70% by the use of an application instrument and a controlling instrument for automatic scanning inspite of the higher costs of investments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00573709
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