0000000000230698
AUTHOR
Rolf Schäfer
The effect of the internal architecture of polymer micronetwork colloids on the dynamics in highly concentrated dispersions
Motivated by the finding that colloidal dispersions of polymer micronetwork spheres with a cross-link density of 1:50 (inverse number of monomer units between crosslinks) show significant deviations from the dynamics of hard spheres in the colloid glass as seen by dynamic light scattering (DLS) (E. Bartsch, V. Frenz, H. Sillescu J. Non — Cryst. Solids 172–174 (1994), 88–97), we have undertaken a systematic study of the effect of the crosslink density on the dynamics at high concentrations. Long-time self-diffusion coefficients D S L and collective diffusion coefficients D c were measured for colloids with crosslink densities of 1:10, 1:20 and 1:50 by forced Rayleigh scattering (FRS) and the…
Collective and self diffusion of PS microgels in solution as observed by thermal diffusion forced Rayleigh scattering
Thermal diffusion in solutions of polystyrene micro-network spheres (microgels) in toluene has been studied by the holographic scattering technique of thermal diffusion forced Rayleigh scattering (TDFRS) and by photon correlation spectroscopy (PCS). Size distributions of microgels of different crosslink ratios are obtained from TDFRS measurements on dilute solutions at very low q-values around 4000cm−1. At low concentrations a single diffusive mode is observed and the diffusion coefficient increases with concentration. It is attributed to the collective diffusion of the microgels and the solvent. At high concentrations an additional slow mode appears whose diffusion coefficient decreases wi…
High-throughput Functional Genomics Identifies Genes That Ameliorate Toxicity Due to Oxidative Stress in Neuronal HT-22 Cells
We describe a novel genetic screen that is performed by transfecting every individual clone of an expression clone collection into a separate population of cells in a highthroughput mode. We combined high-throughput functional genomics with experimental validation to discover human genes that ameliorate cytotoxic responses of neuronal HT-22 cells upon exposure to oxidative stress. A collection of 5,000 human cDNAs in mammalian expression vectors were individually transfected into HT-22 cells, which were then exposed to H2O2. Five genes were found that are known to be involved in pathways of detoxification of peroxide (catalase, glutathione peroxidase-1, peroxiredoxin-1, peroxiredoxin-5, and…