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  • Articles: DFG German National Licenses  (15)
  • Chemistry  (8)
  • Cell elongation  (3)
  • 07.60  (2)
  • ATPase  (2)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    ISSN: 1432-2048
    Keywords: Auxin ; Cell elongation ; Cytochalasin B ; Dictyosomes ; Secretion ; Triticum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochalasin B (CB) inhibits the elongation growth of maize roots, and that of wheat coleoptile segments incubated in indolyl-3-acetic acid, by over 30% after a lag period of about 60 min. This long lag is not due to poor tissue penetration by the inhibitor, but seems to reflect a property of the process inhibited by CB. The only visible ultrastructural change accompanying growth inhibition is the accumulation of secretory vesicles in the vicinity of dictyosomes, which occurs between 90 and 300 min. However, a massive accumulation of vesicles is seen after 120 min in root cap cells which possess very active dictyosomes. The results indicate that CB does not inhibit elongation growth by interfering with cytoplasmic streaming. Instead, they indicate that the drug acts to inhibit the secretion of cell wall components at some stage after vesicle production, but prior to their transport.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2048
    Keywords: Auxin ; Cell elongation ; Epidermis peeling ; Fusicoccin ; Pisum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of peeling and wounding on the indole-3-acetic acid (IAA) and fusicoccin (FC) growth response of etiolated Pisum sativum L. cv. Alaska stem tissue were examined. Over a 5 h growth period, peeling was found to virtually eliminate the IAA response, but about 30% of the FC response remained. In contrast, unpeeled segments wounded with six vertical slits exhibited significant responses to both IAA and FC, indicating that peeling does not act by damaging the tissue. Microscopy showed that the epidermis was removed intact and that the underlying tissue was essentially undamaged. Neither the addition of 2% sucrose to the incubation medium nor the use of a range of IAA concentrations down to 10-8 M restored IAA-induced growth in peeled segments, suggesting that lack of osmotic solutes and supra-optimal uptake of IAA were not important factors over this time period. It is concluded that, although the possibility remains that peeling merely allows leakage of hydrogen ions into the medium, it seems more likely that peeling off the epidermis removes the auxin responsive tissue.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1615-6102
    Keywords: Calcium ; Cell elongation ; Indole-3-acetic acid ; Pisum sativum ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The treatment of dark grown pea stem segments with chelators of divalent cations (EGTA, EDTA, CTC), various Ca2+ antagonists (LaCl3, A-23187, verapamil) and inhibitors of secretory processes (monensin, CB) reduced elongation in the presence of indole-3-acetic acid (IAA). Generally the inhibition increased with increasing concentrations of the substances. The timing of the responses can be correlated with maximum auxin-stimulated secretion of cell wall material. Examination of cell ultrastructure showed that changes in dictyosome activity could explain a reduced deposition of cell wall material and so cause inhibition of elongation. The inhibitors affected the morphology and vesiculation of the dictyosomes, and the appearance of the plasma membrane, ER and mitochondria in different ways. The most pronounced effects on ultrastructure resulted from monensin and LaCl3 treatments with the dictyosomes being most affected; large vesicles appeared in the cytoplasm. Less pronounced effects on cell structure were seen in EGTA, A-23187 and verapamil treated tissue. The effects on the dictyosomes are considered to be due to disturbances of Ca2+ and other ionic levels within the cells.
    Type of Medium: Electronic Resource
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 22-26 
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography ; Dual capillary columns ; Polycyclic aromatic hydrocarbons ; Hop and beer bitter acids ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A chromatograph equipped with one injection valve, two capillary columns with different selectivities, two flame ionization detectors and two electrometers is used to perform simultaneous dual capillary supercritical fluid chromatography. Two sets of retention times and indices are obtained for a mixture of polycyclic aromatic hydrocarbons, from one injection, enabling positive identification. The system is also used to rapidly select a stationary phase for separating hop and beer bittering acids.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 13 (1969), S. 2085-2096 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyethylene, polypropylene, poly(vinyl fluoride) (Tedlar), polystyrene, nylon 6, poly(ethylene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethylene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Polyethylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm-1 in PE, and 887 and 910 cm-1 in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethylene) copolymer gave approximately two-fold increases in lap-shear bond strength. In several cases, significant differences in response to time of treatment and type of excited gas were found.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 1465-1477 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low-density polyethylene, high-density polyethylene (two types), poly(4-methyl-1-pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength-versus-exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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