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Digitale Medien

A simple adsorption model for ionic surfactants (2000)

Semmler, A. ; Kohler, H.-H.

Springer

Colloid & polymer science 278 (2000), S. 911-918

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ISSN: 1435-1536

Schlagwort(e): Key words Ionic surfactants ; Adsorption ; Model ; Isotherm ; Surface tension

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Maschinenbau

Notizen: Abstract In the past, few theoretical attempts have been made to describe quantitatively the adsorption of ionic surfactants at liquid interfaces. Well-known adsorption isotherms due to Frumkin or Hill–de Boer cannot respond to the specific electrostatic and geometric properties of the surfactant molecules. Our approach is based on a combination of the Gouy–Chapman theory with a modified Frumkin isotherm. The modification implies that the system is free to choose an optimal head group area and an optimal arrangement of the surfactant molecules in the interface as a function of bulk concentration. Interaction energies between neighbouring adsorbed surfactant molecules and between surfactant and water molecules are taken into consideration. The minimum of the Gibbs free energy of the system is equivalent to a minimal interfacial tension. Thus, the thermodynamically stable isotherm can be obtained as the lower envelope of the family of σ versus ln c isotherms resulting from different choices of the model parameters, including the area per molecule. According to the Gibbs equation, the Γ versus ln c adsorption isotherm is obtained as the derivative of this envelope. By variation of the model parameters, the envelope of the calculated adsorption isotherms can be fitted to experimental data of the interfacial tension versus bulk concentration. A computer program is used to calculate the σ versus c and the Γ versus ln c curves as well as to fit the parameters.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003960000338

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Digitale Medien

Die Fusion des craniocervicalen Übergangs mit dem „Cervi Fix“ nach überlebter atlanto-occipitaler Dislokation (1998)

Kohler, H. ; Vock, B. ; Hochstein, P. ; [weitere]

Springer

Der Chirurg 69 (1998), S. 677-681

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ISSN: 1433-0385

Schlagwort(e): Key words: Atlanto-occipital dislocation ; Anatomy ; Clinical features ; Operative treatment. ; Schlüsselwörter: Atlanto-occipitale Dislokation ; Anatomie ; Klinik ; operative Therapie.

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: Zusammenfassung. Wir berichten über einen jungen Mann, der als Mofafahrer von einem Pkw mitgeschleift wurde und dabei eine atlanto-occipitale Dislokation erlitt. Er überlebte die Verletzung tetraplegisch. Der Unfallmechanismus, die anatomischen Besonderheiten und die große Variationsbreite der klinischen Symptomatik werden dargestellt. Das von uns gewählte operative Vorgehen wird den in der Literatur beschriebenen Verfahren gegenübergestellt.

Notizen: Summary. We report a rare case of a young moped rider who suffered atlanto-occipital dislocation. He survived with tetraplegia. We discuss the accident mechanism, the anatomical particulars, and the clinical features and compare our operative treatment with the cases described in the literature.