Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 778 (1984), S. 559-569 
    ISSN: 0005-2736
    Schlagwort(e): Conductivity ; Dielectric dispersion ; Intramitochondrial structure ; Membrane capacity ; Mitoplast ; Permittivity ; Single-shell model
    Quelle: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Thema: Biologie , Chemie und Pharmazie , Medizin , Physik
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    ISSN: 1435-1536
    Schlagwort(e): Conductivity ; Dielectric property ; Dielectric relaxation ; Interfacial polarization ; Microcapsule ; Permittivity ; Polystyrene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dielectric measurements were carried out for polystyrene microcapsules which were prepared by means of an interfacial polymer deposition technique. The microcapsules showed a couple of dielectric relaxations termedP for lower andQ for higher frequencies. The frequency profiles were characteristic of the structure that shelled spheres were dispersed in a continuous medium. Gelatin aqueous solutions, cationic polyelectrolyte solutions and distilled water were loaded in the capsule interior to examine the effect of conductivities of the constituent aqueous phases on the dielectric properties. Relaxation frequencies of the relaxationsP andQ observed were directly proportional to the conductivities of the continuous medium and of the capsule interior, respectively. A dielectric theory was proposed for a suspension of shelled spheres in a continuous phase in order to analyze the relaxation data observed for the microcapsules. Volume fraction of the capsules, relative permittivity and conductivity of the capsule interior and thickness of the capsule wall are evaluated from the dielectric observations by use of the theoretical formulas derived. The dielectric behavior observed for the polystyrene microcapsules are interpreted quantitatively in terms of the dielectric theory proposed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 260 (1982), S. 1029-1034 
    ISSN: 1435-1536
    Schlagwort(e): Dielectric relaxation ; W/O emulsions ; Interfacial polarization ; Permittivity ; Emulsifier ; Electric conductivity ; Disperse system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract An attempt is made to apply dielectric theories of interfacial polarization to observations of dielectric relaxations for W/O emulsions. Approximate formulas for disperse systems in a W/O type were derived from the two theories: one proposed by Maxwell and Wagner for dilute disperse systems of spherical particles, and the other developed by Hanai for concentrated disperse systems. Dielectric measurements were carried out on concentrated W/O emulsions prepared from kerosene and distilled water or KCl aqueous solutions by minimal use of emulsifiers. Marked dielectric relaxations were observed with the emulsions, the dielectric parameters having been determined to characterize the relaxation data. Phase parameters such as relative permittivity, electric conductivity and volume fraction of the disperse phase were evaluated from the dielectric parameters by use of the approximate formulas of the respective theories. The phase parameters evaluated and the frequency dependence of complex permittivity of the W/O emulsions deduced from the theory for concentrated disperse systems are in excellent agreement with the observed data in comparison to that for dilute disperse systems. It is concluded that the dielectric relaxations due to the interfacial polarization of disperse systems of spheres are explained satisfactorily by the theory for concentrated disperse systems.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 269 (1991), S. 1039-1044 
    ISSN: 1435-1536
    Schlagwort(e): Dielectric analysis ; single-shell model ; permittivity ; dielectric mixture equation ; erythrocyte ghost
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The purpose of this study is to confirm the applicability of dielectric mixture equations in dielectric analysis of biological cell suspensions. Two dielectric mixture equations, the Pauly-Schwan (P-S) equation and the Hanai-Asami-Koizumi (H-A-K) equation were tested using sheep erythrocyte ghosts whose internal solution is identical with the external solution. Dielectric measurements were carried out for the ghost suspensions over a frequency range 10 kHz to 100 MHz; a single dielectric relaxation was found between 100 kHz and 10 MHz. From the dielectric relaxation, the conductivity and permittivity of the ghost interior and the capacitance of the cell membrane were calculated following the P-S and H-A-K equations. When the H-A-K equation was employed (and as expected from the property of the ghosts), the estimated internal conductivity was in good agreement with the external conductivity at volume fractions up to about 0.7. With the P-S equation, on the other hand, the same results as above were obtained but only at low volume fractions below about 0.3. In addition, the H-A-K equation provided a better simulation for the observed relaxation curves than did the P-S equation, especially at high volume fractions. It is, therefore, concluded that the H-A-K equation is applicable to a wider range of volume fraction than is the P-S equation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 262 (1984), S. 477-480 
    ISSN: 1435-1536
    Schlagwort(e): Dielectric property ; permittivity ; electrical conductivity ; ion-exchanger ; interfacial polarization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dielectric measurements were carried out for dense sediments of quaternary ammonium type anion-exchange resin beads dispersed in deionized water over a frequency range of 30 Hz to 130 MHz. According to a method proposed in previous studies the relative permittivities and electrical conductivities of ion-exchange beads were evaluated from the relaxation data observed in a megahertz region on the basis of a theory of interfacial polarization. The permittivities of the ion-exchange beads were found to be unchanged irrespectively of the salt form and somewhat lower than that of a continuous medium, while the conductivities of the ion-exchange beads were characteristic of the salt form. The equivalent ionic conductances of different counter anions in the beads were estimated from the conductivities of the ion-exchange beads. These results indicate an ion-binding effect in the resin beads.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    ISSN: 1435-1536
    Schlagwort(e): Dielectric property ; dielectric relaxation ; microcapsule ; permittivity ; polystyrene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract A method of numerical analysis is proposed to determine the phase parameters from dielectric observations of polystyrene microcapsules by using the conductivity at intermediate frequencies between two dielectric relaxations observed. The method was more feasible for the analysis of the microcapsule observations than the method by which the calculation is performed by use of the permittivity at lower frequencies. The method was applied to the dielectric observations of the KCl-loaded microcapsules to obtain the permittivity and the conductivity of the capsule interior, the thickness of the capsule wall, the volume fraction of the suspended capsules and the conductivity of the surrounding aqueous phase. The conductivity of capsule interior was found to be unchanged with time for as long as 3 months. From the results it is concluded that the microcapsules are impermeable to KCl.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 428-432 
    ISSN: 1435-1536
    Schlagwort(e): Dielectric property ; dielectric relaxation ; permittivity ; electrical conductivity ; ion-exchanger
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Ion-exchange beads with different densities of fixed charges were prepared by sulfoethylation of dextran gel beads. The relative permittivities and the electrical conductivities of the ion-exchange beads in a sodium form were evaluated by a dielectric technique consisting of the following two procedures proposed in a previous study (2): (a) Dielectric measurements for densely packed sediments of the ion-exchange beads; (b) Analysis of the observed dielectric relaxations by means of a theoretical equation of interfacial polarization for suspensions of spherical particles. The deduced permittivities of the ionexchange beads in equilibrium with water were about 60, which is lower than those of outer aqueous phases. The deduced conductirities were of the order of 1 to 10 mS cm−1 and were increased reasonably with the fixed charge density. Closer consideration on these deduced values indicates that no specific interaction exists between the counter ions and the fixed charges irrespective of changes in fixed charge density and temperature.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 17 (1983), S. 633-639 
    ISSN: 1612-1112
    Schlagwort(e): Macro porous polystyrene gel and the ion-exchange resins ; Aromatic acids ; Hydrophobicity ; Dissociation constant ; lon-pair
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention behaviour of aromatic acids was examined in a reversed-phase mode liquid chromatography. Macro porous styrene-divinylbenzene copolymers were selected on the basis of their chemical stability throughout the entire pH range. The effect of addition of a hydrophobic ion in the eluent and that of an ion-exchange group on the packing were discussed in relation with the hydrophobicity and the dissociation constant of solutes. The maximum capacity ratios of the acids on apolystyrene gel are linearly related with the hydrophobicity. The prediction of the retention time of aromatic acids could be possible by combination of their hydrophobicity and their dissociation constants.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 12 (1979), S. 77-82 
    ISSN: 1612-1112
    Schlagwort(e): Liquid chromatography ; Qualitative analysis ; Hydrophobicity ; Reversed phase mode chromatography ; Calculation of solvent concentration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The possibility of qualitative analysis by liquid chromatography is discussed in systems of polystyrene gel or chemically bonded octadecyl packing with alcohols as standard compounds. Rekker's hydrophobic fragmental constants are used for identification purposes. Capacity ratios for alcohols can be calculated from the hydrophobicities in spite of changes in solvent mixture ratios if the capacity ratio for an internal standard compound is measured.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...