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Université de Fribourg

Assessing meso- and microplastic pollution in the Ligurian and Tyrrhenian Seas

Caldwell, Jessica ; Petri-Fink, Alke ; Rothen-Rutishauser, Barbara ; Lehner, Roman

In: Marine Pollution Bulletin, 2019, vol. 149, p. 110572

As the production of plastic products continues to increase, determining the fate of plastic waste in the environment is of high importance. Densely populated areas, such as Mediterranean coastlines, represent locations of high pollution risk for surrounding environments. Thus, this study aims to assess the abundance, size, and composition of floating meso- and microplastics collected during...

Université de Fribourg

Colloidal dynamics and elasticity of dense wax particle suspensions over a wide range of volume fractions when tuning the softness by temperature

Yoon, Jiwon ; Scheffold, Frank ; Ahn, Kyung Hyun

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019, vol. 576, p. 1–8

We report on the colloidal dynamics and rheology of liquid droplet emulsions and solid particle suspensions over a wide range of volume fractions. Diffusing wave spectroscopy and rheometry were utilized to study the micro/macroscale properties of 1-eicosene wax particles dispersed in water. By changing the temperature, the wax droplets change their properties from soft to hard or vice versa,...

Université de Fribourg

Serial electron microscopic reconstruction of the drosophila larval eye: Photoreceptors with a rudimentary rhabdomere of microvillar-like processes

Hartenstein, Volker ; Yuan, Michaela ; Younossi-Hartenstein, Amelia ; Karandikar, Aanavi ; Bernardo-Garcia, F. Javier ; Sprecher, Simon G. ; Knust, Elisabeth

In: Developmental Biology, 2019, vol. 453, no. 1, p. 56–67

Photoreceptor cells (PRCs) across the animal kingdom are characterized by a stacking of apical membranes to accommodate the high abundance of photopigment. In arthropods and many other invertebrate phyla PRC membrane stacks adopt the shape of densely packed microvilli that form a structure called rhabdomere. PRCs and surrounding accessory cells, including pigment cells and lens-forming cells,...

Université de Fribourg

Relationship between rheology and structure of interpenetrating, deforming and compressing microgels

Conley, Gaurasundar M. ; Zhang, Chi ; Aebischer, Philippe ; Harden, James L. ; Scheffold, Frank

In: Nature Communications, 2019, vol. 10, no. 1, p. 2436

Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles in a unique way. Due to their complex morphology, their interactions and packing, and consequentially the viscoelasticity of suspensions made from microgels, are still not fully understood, in particular under dense packing conditions. Here we study the frequency-dependent...

Université de Fribourg

Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale

Obu, Jaroslav ; Westermann, Sebastian ; Bartsch, Annett ; Berdnikov, Nikolai ; Christiansen, Hanne H. ; Dashtseren, Avirmed ; Delaloye, Reynald ; Elberling, Bo ; Etzelmüller, Bernd ; Kholodov, Alexander ; Khomutov, Artem ; Kääb, Andreas ; Leibman, Marina O. ; Lewkowicz, Antoni G. ; Panda, Santosh K. ; Romanovskyh, Vladimir ; Wayk, Robert G. ; Westergaard-Nielsen, Andreas ; Wu, Tonghua ; Yamkhin, Jambaljav ; Zou, Defu

In: Earth-Science Reviews, 2019, vol. 193, p. 299–316

Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016...

Université de Fribourg

Structure and sedimentation kinetics of dense suspensions of fibroblast cells

Zenuni, Arbnor ; Zhang, Chi ; Haeni, Laetitia ; Rothen-Rutishauser, Barbara ; Scheffold, Frank

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 43–46

We investigate the structure and the dynamics of dense suspensions of NIH 3T3 fibroblast cells. Using two-photon microscopy we obtain three dimensional (3D) images from which the size and the packing structure of the dense cell suspensions can be extracted. In addition, we analyse the global time-dependent behaviour of the suspensions by time-lapse measurements of cell sedimentation. Since...