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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 33 (1984), S. 179-185 
    ISSN: 1432-0649
    Keywords: 06 ; 07.60 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a study, performed using heterodyne techniques, of the frequency fluctuations of two completely independent ring dye lasers locked to independent reference cavities. Single laser linewidths of less than 750 Hz were achieved, the principal limitation being residual vibrations from the noisy laboratory environment. With future design and environmental improvements, ultranarrow linewidths are expected thus providing a useful tool for a great variety of high precision experiments.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: ATPase ; Plasma membrane ; Pyrophosphatase ; Ricinus (solute transport) ; Sucrose transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A highly enriched plasma membrane fraction has been isolated from dark-grown cotyledons ofRicinus communis by phase partitioning. This is demonstrated by the properties of the associated ATPase: high vanadate sensitivity, azide and nitrate insensitivity, sharp pH optimum around 6.5, and high specificity for ATP as substrate. The upper plasma membrane fraction also contained a pyrophosphatase activity, normally considered to be located on the tonoplast or Golgi membranes, which showed a specific activity higher than that in the lower phase. Sucrose gradient centrifugation of both microsomal and upper phase fractions showed a comigration of some pyrophosphatase activity with the plasma membrane fraction. Sucrose uptake changes with development inRicinus cotyledons. The ATPase activity in the upper (plasma membrane) phase also varied in a similar way with development, whereas activity in the lower phase showed little change. Pyrophosphatase activity in the upper phase also increased with development but did not show a peak and fall as seen for sucrose uptake and ATPase. The possibility that changes in plasma membrane ATPase may contribute to changes in sucrose uptake capacity and the possible cellular origin and physiological significance of the pyrophosphatase activity are discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0649
    Keywords: 06 ; 07.60 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a new and highly effective optical frequency discriminator and laser stabilization system based on signals reflected from a stable Fabry-Perot reference interferometer. High sensitivity for detection of resonance information is achieved by optical heterodyne detection with sidebands produced by rf phase modulation. Physical, optical, and electronic aspects of this discriminator/laser frequency stabilization system are considered in detail. We show that a high-speed domain exists in which the system responds to the phase (rather than frequency) change of the laser; thus with suitable design the servo loop bandwidth is not limited by the cavity response time. We report diagnostic experiments in which a dye laser and gas laser were independently locked to one stable cavity. Because of the precautions employed, the observed sub-100 Hz beat line width shows that the lasers were this stable. Applications of this system of laser stabilization include precision laser spectroscopy and interferometric gravity-wave detectors.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 165 (1991), S. 27-36 
    ISSN: 1615-6102
    Keywords: ATPase ; Cerium ; Cytochemistry ; Fixation ; Zea mays roots ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cytochemical localization of ATPase activity has been investigated in maize root cells using both lead and cerium-based capture methods. With both methods, staining at the plasma membrane was observed in all cells of the root, although the precipitate obtained with cerium was more uniform and granular than that with lead. Controls using no substrate or no magnesium, β-glycerophosphate to replace ATP, vanadate or boiled tissue generally showed little or no staining. However, biochemical studies on purified plasma membrane fractions showed that ATPase activity was markedly inhibited by fixation, particularly by glutaraldehyde, and also by lead and cerium ions. Non-enzymic hydrolysis of ATP by cerium was greater than that by lead. The value and limitations of these procedures for the localization of plasma membrane H+-ATPase activity are summarized in relation to previous criticisms of these methods.
    Type of Medium: Electronic Resource
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