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  • 1990-1994  (8)
  • 1980-1984  (14)
  • Polymer and Materials Science  (18)
  • Auxin and stem growth  (2)
  • Data regression
  • Ionogene substances
  • Life and Medical Sciences
Material
Years
Year
Keywords
  • 1
    ISSN: 1434-4475
    Keywords: Absorption equilibrium ; Data regression ; Ionogene substances ; Maximum likelihood principle ; Reaction equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solubility of ionogen substances in water and aqueous ionic solutions is important for calculation of absorption processes. Aqueous solutions with complex reaction systems behave themselves extremely nonideal. In simple cases equilibria can be determined with the concept of nonideal thermodynamics. The model used in this work is based on ideal calculation of reaction equilibria and gas solubility. The model parameters (equilibrium constants andHenry constants) for the systems SO2-H2O,MEA-H2S-H2O,DEA-H2S-H2O andMEA-CO2-H2O are computed by regression of experimental data. Equilibrium reactions are selected according toBrinkley's method. The selection of the reacting species has decisive influence on the accuracy of the data fitting. Data regression is done numerically and leads to the formulation of nonlinear systems of equations, which have to be solved for each data point. This solutions are performed in an inner loop. By using the maximum-likelihood-principle the model parameters are optimized in the superior regression loop. Experimental data for the regression are the partial pressure and the total concentration of gas in the liquid phase. The used model is able to fit these data satisfactoryly. The model parameters, which are calculated from simultaneous data regression for different temperatures, ensure a simple correlation ofvan't Hoff. However, for similar reactions equilibria in different reaction systems, it is impossible to compute the same values for the equilibrium constants.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Auxin and stem growth ; Epidermis and stem growth ; Pisum (stem growth) ; Phytochrome stem growth ; Stem elongation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of red (R) and far-red (FR) light on stem elongation and indole-3-acetic acid (IAA) levels was examined in dwarf and tall Pisum sativum L. seedlings. Red light reduced the extension-growth rate of etiolated seedlings by 70–90% after 3 h, and this inhibition was reversible by FR. Inhibition occurred throughout the growing zone. After 3 h of R, the level of extractable IAA in whole stem sections from the growing zone of etiolated plants either increased or showed no change. By contrast, extractable IAA from epidermal peels consistently decreased 3 h after R treatments. Decreases of 40% were observed for epidermal peels from the top 1 cm of tall plants receiving 3 h R. Brief R treatments resulted in smaller decreases in epidermal IAA levels and these decreases were not as great when FR followed R. In lightgrown plants, end-of-day FR stimulated growth during the following dark period in a photoreversible manner. The uppermost 1 cm of expanding third internodes was most responsive to the FR. Extractable IAA from epidermal peels from the upper 1 cm of third internodes increased by 30% or more 5 h after FR. When R followed the FR the increases were smaller. Levels of IAA in whole stem sections did not change and were twofold greater than in dark-grown plants. In both dark- and light-grown tall plants, IAA levels were lower in epidermal peels than in whole stem segments. These results provide evidence that IAA is compartmentalized at the tissue level within the growing stem and that phytochrome regulation of stem elongation rates may be partly based on modulating the level of IAA within the epidermis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Auxin and stem growth ; Epidermis and stem growth ; Pisum (stem growth) ; Phytochrome stem growth ; Stem elongation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of red (R) and far-red (FR) light on stem elongation and indole-3-acetic acid (IAA) levels was examined in dwarf and tallPisum sativum L. seedlings. Red light reduced the extension-growth rate of etiolated seedlings by 70–90% after 3 h, and this inhibition was reversible by FR. Inhibition occurred throughout the growing zone. After 3 h of R, the level of extractable IAA in whole stem sections from the growing zone of etiolated plants either increased or showed no change. By contrast, extractable IAA from epidermal peels consistently decreased 3 h after R treatments. Decreases of 40% were observed for epidermal peels from the top 1 cm of tall plants receiving 3 h R. Brief R treatments resulted in smaller decreases in epidermal IAA levels and these decreases were not as great when FR followed R. In lightgrown plants, end-of-day FR stimulated growth during the following dark period in a photoreversible manner. The uppermost 1 cm of expanding third internodes was most responsive to the FR. Extractable IAA from epidermal peels from the upper 1 cm of third internodes increased by 30% or more 5 h after FR. When R followed the FR the increases were smaller. Levels of IAA in whole stem sections did not change and were twofold greater than in dark-grown plants. In both dark- and light-grown tall plants, IAA levels were lower in epidermal peels than in whole stem segments. These results provide evidence that IAA is compartmentalized at the tissue level within the growing stem and that phytochrome regulation of stem elongation rates may be partly based on modulating the level of IAA within the epidermis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We show how narrow spectral holes burnt into the inhomogeneous absorption of dye doped polymers can be used as extremely sensitive detectors for measuring structural rearrangement processes. A model is suggested which relates the observed hole burning phenomena to the specific heat of the conformation phase space.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyethylenes of different crystallinity and crosslinking were etched plasmachemically for revealing supermolecular structures. Electron microscopic patterns of the etched polymer surfaces show differences in the degree of crystallinity up to 3%.
    Notes: Polyethylenproben unterschiedlicher Kristallinität und Vernetzung wurden zur Freilegung übermolekularer Strukturen plasmachemisch geätzt. Die elektronemikroskopischen Aufnahmen der geätzten Polymeroberflächen zeigten, daß sich Unterschiede im Kristallinitätsgrad bis zu 3% im Ätzrelief widerspiegeln.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: As detected by photoelectron spectroscopy (ESCA) no saturation in concentration of N-containing groups occurs on the surface of polypropylene up to 50 minutes exposition in NH3 plasma. Under the particular conditions of the plasma the presence of amino groups is suggested. No large changes in structure of layers under the surface (up to 100 μm) were observed. The surface was roughed strongly by O2 plasma treatment. The etching patterns correspond to those of a predominantly monoaxialy stretched polymer.
    Notes: Bei der Behandlung von Polypropylenfolien im NH3-Plasma trat nach photoelektronenspektroskopischen Untersuchungen bis mindestens 50 min Behandlungszeit keine Sättigung der Konzentration an N-haltigen funktionellen Gruppen an der Polymeroberfläche ein. Bei den speziell gewählten Plasmabedingungen kann auf das Vorliegen von NH2-Gruppen geschlossen werden. Strukturelle Veränderungen in tieferliegenden Schichten traten kaum auf. Durch O2-Plasmabehandlung wurde die Folienoberfläche stark aufgerauht. Die Ätztruktur entsprach einem überwiegend monoaxial gereckten Polymer.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Carbon fibres were modified by different N containing groups at the surface in a nonthermal NH3-plasma. This was estimated by means of photoelectron spectroscopy. During the plasma exposition a layer of low molecular hydrogenated products formed at the surface. By plasma exposition the wetting of fibres with epoxy resin was increased.
    Notes: Kohlenstoff-Fasern wurden in einem nichtthermischen NH3-Plasma an der Oberfläche mit verschiedenartigen Nhaltigen Gruppen funktionalisiert, was mit Hilfe der Photoelektronenspektroskopie nachgewiesen wurde. Im Verlaufe der Plasmabehandlung entstand an der Faseroberfläche eine Schicht niedermolekularer, hydrierter Produkte. Die Benetzung der Fasern mit Epoxidharz wurde durch die Plasmabehandlung verbessert.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 553-554 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 42 (1991), S. 51-52 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The investigation of the temperature dependence of polymer etching rates in an oxygen plasma was extented to some more polymers. The complex nature of the etching process becomes obvious, because the temperature dependences are often nonlinear. Characteristic changes in the slope of the curves correspond only in some cases with the glass temperature of the polymers. Therefore these points can also be connected with the formation and etching of adsorption layers. Activation energies of partial processes were determined. Based on the temperature dependence, only some general conclusions on the plasma etching mechanism could be derived.
    Notes: Die Untersuchung von Temperaturabhängigkeiten der Plasmaätzrate von Polymeren im Sauerstoffplasma wurde auf weitere Polymere ausgedehnt. Die Temperaturabhängigkeit der Plasmaätzrate ist teilweise sehr unterschiedlich, was auf einen sehr komplexen Mechanismus des Ätzprozesses hindeutet. Charakteristische Knickpunkte in den Kurven konnten nur in einigen Fällen mit der Glastemperatur des Polymers in Verbindung gebracht werden. Möglicherweise werden diese Knickpunkte auch durch Abtrag und Bildung von Adsorptionsschichten hervorgerufen. Aktivierungsenergien von Teilprozessen wurden bestimmt. Aus den Temperaturabhängigkeiten allein ließen sich nur allgemeine Schlußfolgerungen über den Mechanismus des Plasmaätzens der einzelnen Polymere ableiten.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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