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  • Cell & Developmental Biology  (9)
  • Adsorption kinetics  (7)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 260 (1982), S. 1148-1150 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; model of diffusion-kinetic-controlled adsorption ; effect of impurities on adsorption kinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract By means of a theoretical experiment it is demonstrated, that a barrier in the adsorption kinetics of a surfactant can be simulated by the presence of surface-active impurities. Hence, the application of models for the diffusion-kinetic-controlled and/or kinetic controlled adsorption presumes the proof of the surface chemical purity of the surfactant solution under investigation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 264 (1986), S. 357-361 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; ring and plate method ; nonionic surfactants at solution/ air interface
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dynamic surface tension values of aqueous surfactant solutions were measured by using the ring and plate method. The mean diffusion coefficients calculated on the basis of the purely diffusion controlled adsorption model vary between 2 · 10−6 to 7 · 10−6 cm2/s for all surfactants studied:n-alkanols,n-alkanoic acids, dimethyl and diethyln-alkyl phosphine oxides. That means the surfactants investigated adsorb with a purely diffusion controlled adsorption mechanism and no barriers excist to hinder sorption processes.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 266 (1988), S. 532-538 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; surfactant transport ; Langmuir isotherm
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The model of diffusion-controlled adsorption kinetics can be solved by different mathematical procedures. For the most important case of a Langmuir isotherm, useful solutions are summarized and extended and the ranges of application are given. New approximations are presented which can be applied to most experiments in practice.
    Materialart: Digitale Medien
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  • 4
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; ionic surfactants ; non-equilibrium electric double layer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract An approximate analytical solution is obtained for the adsorption kinetics equation derived earlier. On the basis of these relations the importance of the consideration of a non-equilibrium diffuse layer has been shown. To describe the retarded adsorption kinetics the distribution of adsorbed ions in the diffuse layer section of multivalent surfactant ions has been taken into account. The rate of adsorption calculated for a non-ionic surfactant is compared with the adsorption rate for monovalent and bivalent ionic surfactants, respectively.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 261 (1983), S. 335-339 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; ionic surfactants ; influence of the electric double layer ; theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The influence of the electric field caused by an electric double layer (DL) on the adsorption kinetics of charged surfactant molecules at fluid interfaces is described for the case of high surface potentials and a quasi-equilibrium state of the DL. Known relations for the description of the transport of molecules in the diffusion layer and the DL respectively are used.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 105 (1997), S. 346-350 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; surfactants ; transfer across ; interface ; interfacial tension ; water/hexane ; n-alkyl dimethyl phosphine oxides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The adsorption kinetics of alkyl phosphine oxides soluble both in water and in alkanes has been experimentally studied by measuring the dynamic interfacial tension. To this aim the pendant drop method was used with an automatic acquisition of the drop shape (ASTRA). The experimental results show that under particular geometrical and initial conditions, the dynamic interfacial tension exhibits a minimum. This nonmonotonic behaviour can be explained by considering the transfer of matter through the surface during the adsorption and the depletion of one phase necessary to establish the partition equilibrium. These data can be interpreted on the basis of a diffusion controlled adsorption model involving two finite phases. Moreover a particular experimental procedure for measuring the partition coefficient has been used based on the equilibrium surface tension measurements and on the evaluation of the adsorption isotherm.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 259 (1981), S. 1124-1128 
    ISSN: 1435-1536
    Schlagwort(e): Adsorption kinetics ; surfactants ; micellar solutions ; theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Es wird ein Modell für die diffusionskontrollierte Adsorption von Tensiden aus mizellaren Lösungen angegeben und numerisch gelöst. Das dabei zugrundegelegte Modell für die Mizellkinetik entspricht einem Bildungs-Auflösungs-Mechanismus. Es wird der Einfluß von Parametern wie Mizellkonzentration, Assoziationsgrad, Geschwindigkeitskonstanten der Mizellkinetik auf die Adsorptionskinetik diskutiert.
    Notizen: Summary A model of diffusion controlled adsorption of surfactants from micellar solutions is given and numerically solved. The model used to describe the micelle kinetics corresponds to a formation-dissolution mechanism. Parameters like micelle concentration, aggregation number, rate constant of formation or dissolution of micelles influencing the adsorption process are discussed.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 38 (1988), S. 35-49 
    ISSN: 0730-2312
    Schlagwort(e): alfalfa ; dicarboxylic acid ; energy source ; chlorpromazine ; bacteroid ; nitrogenase ; respiration ; rhizobium meliloti ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Bacteroids having a high level of respiration-supported nitrogenase activity were isolated from nitrogen-fixing alfalfa root nodules. Gentle maceration under anaerobic conditions in the presence of sodium succinate and a fatty acid scavenging agent were employed in this method.A large proportion of isolated bacteroids retained a triple membrane structure as shown by transmission electron microscopy. Dicarboxylic acids of the TCA cycle (malate, fumarate, succinate), but not glutamate or aspartate, supported sufficient respiratory activity to supply the nitrogenase system with ATP and reducing equivalents and to protect the nitrogenase system from inactivation by 4% oxygen over a period of 20-30 min. Sugars did not support nitrogenase activity in intact bacteroids. The properties of the isolated bacteroids were ascribed to minimal damage to the cytoplasmic membrane and peribacteroidal membrane during isolation.With succinate as substrate and oxygen as terminal electron acceptor, initial nitrogenase activity was determined at 4% oxygen in the gas phase of the assay system employed. At this oxygen concentration, the sustained rate of acetylene reduction by respiring bacteroids was linear up to 30 min. Bacteroid activity declined rapidly with time of exposure to oxygen above 4% in the gas phase. The optimum temperature range for this activity was 10-20°C. Nitrogenase activity was measurable at incubation tempertures below 10°C under 4% oxygen. Functionally intact bacteroids had little nitrogenase activity under anaerobic conditions in the presence of an external source of ATP and reductant. Treatment of the bacteroids with chlorpromazine eliminated respirtation-supported activity and rendered the bacteroid cell membrane permeable to external ATP. Bacteroids treated with chlorpromazine had high acetylene reducing activity with external ATP and dithionite in the absence of oxygen.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 9
    ISSN: 0003-276X
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 219 (1994), S. 257-267 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The ovary of the salp Pegea socia (Bosc, 1802) is located at the end of an atrial diverticulum. The ovary consists of a single oocyte encased in a layer of follicle cells and is connected to the atrial epithelium by an oviduct. Transmission electron microscopy shows that the oocyte lacks a vitelline layer, cortical granules, and yolk granules and that the oviduct lacks a continuous lumen. What previous authors thought was a lumen is a line of dense intercellular junctions running down the center of the oviduct. The sperm nucleus in this species, as in other salps, is elongate. The tubular mitochondrion spirals about the sperm nucleus giving it a corkscrew-shape appearance. Sperm reach the ovary when the oocyte is still at the germinal vesicle stage. Many sperm swim up the atrial diverticulum and burrow through the cells of the atrial epithelium, oviduct, and follicular epithelium. Thus oviduct shortening, which occurs when the oocyte is in the meiotic divisions, is evidently unrelated to sperm moving up the oviduct. All previous authors, who argued either that a continuous lumen is necessary for sperm to move up the oviduct or that sperm bypass the oviduct, were incorrect. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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