In: Journal of the Optical Society of America: A, 2004, vol. 21, p. 1799-1804
We formulate a quantitative description of backscattered linearly polarized light with an extended photon diffusion formalism taking explicitly into account the scattering anisotropy parameter g of the medium. From diffusing wave spectroscopy measurements, the characteristic depolarization length for linearly polarized light, lp, is deduced. We investigate the dependence of this length on the...
|
In: Current Opinion in Colloid & Interface Science, 2004, vol. 8, p. 494-500
The analogies between colloidal glasses and gels have stimulated an increased effort in recent years to unify the description of the transitions to these disordered solid-like states within a single conceptual framework. Mode coupling theory, which successfully describes the hard sphere colloidal glass transition, has been extended to describe the effect of weak attractions at large volume...
|
In: Carbohydrate Polymers, 2004, vol. 55, p. 155-161
We have studied the rheological properties of the natural biopolymer system starch in the presence of the gelation inducing flavor compound γ-dodecalactone. From optical microrheology, based on the multiple scattering of laser light (DWS), we deduce the frequency-dependent moduli G(ω) and G″(ω) of the gelling sample over the full frequency range. Our measurements demonstrate the inherent...
|
In: Journal of Colloid and Interface Science, 2004, vol. 271, p. 163-173
Hydrous ferric oxides (HFO) are efficient sorbents for inorganic and organic pollutants and therefore have great potentials in environmental science and engineering applications. Freezing and thawing of HFO suspensions leads to the formation of dense HFO aggregates. It facilitates the handling and increases the drying rate of HFO. In this study, we used a combination of pycnometry, gas adsorption...
|
In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004, vol. 250, p. 325-336
Polymer–droplet interactions have been studied in AOT/water/isooctane oil-continuous microemulsions mixed with an amphiphilic graft copolymer, or with the parent homopolymer (AOT = sodium bis(2-ethylhexyl) sulfosuccinate). The graft copolymer has an oil-soluble poly(dodecyl methacrylate) backbone and water-soluble poly(ethylene glycol) side chains. Pseudo-ternary polymer/droplet/isooctane phase...
|
Thèse de doctorat : Université de Fribourg : 2002 ; no 1388.
The biocompatibility of materials in implant or biosensor fields strongly depends on first interactions occurring between a given surface and a biological environment. It is well-known that a living body brought into contact with a surface will induce protein adsorption, which creates the interface, on which proteins or cells will adsorb. The interactions can be influenced by modifying the...
|
Thèse de doctorat : Université de Fribourg : 2000 ; no 1302.
This thesis describes the development and the applications of four wave mixing techniques (Transient Grating (TG), Coherent Anti-Stokes Raman Scattering (CARS) and Transient Dichroism (TD)), to investigate processes taking place in the pico- and femtosecond time scales. In the first part of the work, the TG technique is described using both the holography and the nonlinear optics formalisms. The...
|
Thèse de doctorat : Université de Fribourg : 2000 ; no 1303.
Starting from the El Farol's bar problem, we introduce the minority game, an extremely simple model of competition between adaptive agents. We study its properties, and find that it displays a phase transition with symmetry breaking. An adequate mathematical formalism is introduced and reveals the spin glass nature of the model. We prove that available information is a Lyapunov function for this...
|
Thèse de doctorat : Université de Fribourg : 2000 ; Nr. 1326.
The study of nuclear structure is one of the research domains in nuclear physics which have known an important development. It has asked a great effort for the experimenters as well as the theoreticians to study in detail the nuclear many-body problem. In the framework of this thesis, we have tested several nuclear models for two nuclei: 110Cd and 114Te. This choice has not been made at random....
|
Thèse de doctorat : Université de Fribourg : 2002 ; 1374.
Das Problem wechselwirkender Elektronen in zwei Dimensionen ist spätestens seit der Entdeckung der Hoch-Temperatur-Supraleitung von grosser Aktualität und Gegenstand intensiver Forschungstätigkeit. In der vorliegenden Arbeit wird ein erweitertes Hubbard-Modell auf einem Quadratgitter untersucht. Obwohl man weiss, dass die Leitungselektronen in den Kupraten relativ stark miteinander...
|
