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Université de Fribourg

Monitoring of air radioactivity at the Jungfraujoch research station: Test of a new high volume aerosol sampler

Flury, Thomas ; Völkle, Hansruedi

In: Science of The Total Environment, 2008, vol. 391, no. 2-3, p. 284-287

The Swiss Federal Office of Public Health (SFOPH) is responsible for the surveillance of environmental radioactivity in Switzerland and for the protection of the public from ionizing and non-ionizing radiation. In order to improve the Swiss radioactivity monitoring network, a new high volume air sampler (DIGITEL DHA-80) was tested in Fribourg and at the Jungfraujoch High Altitude Research Station...

Université de Fribourg

New insight into cataract formation: enhanced stability through mutual attraction

Stradner, Anna ; Foffi, G. ; Dorsaz, N. ; Thurston, G. ; Schurtenberger, Peter

In: Physical Review Letters, 2007, vol. 99, no. 19, p. 198103

Small-angle neutron scattering experiments and molecular dynamics simulations combined with an application of concepts from soft matter physics to complex protein mixtures provide new insight into the stability of eye lens protein mixtures. Exploring this colloid-protein analogy we demonstrate that weak attractions between unlike proteins help to maintain lens transparency in an extremely...

Université de Fribourg

Cluster, glass, and gel formation and viscoelastic phase separation in aqueous clay suspensions

Shalkevich, Andrey ; Stradner, Anna ; Bhat, Suresh Kumar ; Muller, François ; Schurtenberger, Peter

In: Langmuir, 2007, vol. 23, no. 7, p. 3570 -3580

We have systematically investigated the phase diagram of clay particles in water to understand the relation between the local and macroscopic properties and the structures of clay suspensions. We focused, in particular, on sodium Cloisite (CNa) particles at concentrations typically used in nanocomposites (concentrations from 1 to 4 wt %) and at an extended range of ionic strengths (10⁻⁵ to...

Université de Fribourg

Pierre de Jean Olivi et la subjectivité angélique

Suarez-Nani, Tiziana ; Université de Fribourg

In: Archives d'histoire doctrinale et littéraire du Moyen-Âge, 2003, vol. 70, p. 233 - 316

Université de Fribourg

Transport of light in amorphous photonic materials

Reufer, Mathias ; Rojas-Ochoa, Luis Fernando ; Eiden, Stefanie ; Sáenz, Juan José ; Scheffold, Frank

In: Applied Physics Letters, 2007, vol. 91, no. 17, p. 171904

Amorphous photonic materials based on dense assemblies of high refractive index spherical particles are presented. Light transmission through these photonic glasses shows a nontrivial wavelength dependence. The transmission spectra can be quantitatively reproduced by modeling the optical properties starting from their building blocks. Our results emphasize the relevance of including short range...

Université de Fribourg

New trends in light scattering

Scheffold, Frank ; Cerbino, Roberto

In: Current Opinion in Colloid & Interface Science, 2007, vol. 12, no. 1, p. 50-57

In this article we review some of the most important new developments in light scattering that have emerged over the past 10 years. Some of the new methods substantially extend the range of accessible time and length scales. Different cross-correlation methods are now available to suppress multiple scattering over a large concentration range. Novel low coherent light sources on the other hand...

Université de Fribourg

The influence of the scattering anisotropy parameter on diffuse reflection of light

Pierrat, R. ; Ben Braham, Nasser ; Rojas-Ochoa, Luis Fernando ; Carminati, R. ; Scheffold, Frank

In: Optics Communications, 2008, vol. 281, no. 1, p. 18-22

We discuss the impact of the scattering anisotropy parameter on the path length distribution of multiply scattered light. A quantitative treatment based on the radiative transfer equation is compared to an extended photon diffusion formalism. We compare both models with diffusing-wave spectroscopy measurements using randomly polarized light.