20 research outputs found
a transparent plastic varnish with nanoparticulate magnetic additives
For the purpose of preparing TCCs (= transparent and electrical conducting
coatings), metallic and ferromagnetic nano-additives were dispersed into a
transparent varnish and the obtained dispersions were coated on transparent
plastic substrates. During hardening of the dispersion the magnetic nano-
additives were aligned by a magnetic field. The resulting coatings have
electrical pathways along lines of nano-additive chains and are highly
transparent in the areas between the lines. Therefore, the electrical
conductivity is anisotropic, and it depends on the alignment of the nano-
additives (i.e. on the distance between the nano-additives within the chains
and the length of the lines) as well as on the thickness of an oxide and/or
solvent shell around the nano-additives. The transparency depends also on the
alignment and here especially on the thickness and the distance between the
formed lines. The quality of the alignment in turn, depends on the magnetic
properties and on the size of the particles. We used commercial plastic
varnishes, which form electrically isolating (≥ 10− 12 S/m) and transparent
(about 90% transparency) coatings, and the following magnetic additives: Co-,
Fe-, CoPt3, CoPt3@Au- and Fe@Au-nanoparticles as well as CoNi-nanowires.
Coatings with Fe@Au-nanoparticles show the best results in terms of the
electrical conductivity (10− 5 S/m–10− 6 S/m) at transparencies above 70%.
Furthermore, in addition to the magnetic nano-additives, transparent additives
(Al2O3-particles) and non-magnetic, but better conducting additives (carbon-
nanotubes) were added to the varnish to increase the transparency and the
electrical conductivity, respectively
078. 1-26-81 John 4
Chapel Sermon by F Stiemke on Monday, January 26, 1981
Canonical Wnt/beta-Catenin Signalling Is Essential for Optic Cup Formation
A multitude of signalling pathways are involved in the process of forming an eye. Here we demonstrate that beta-catenin is essential for eye development as inactivation of beta-catenin prior to cellular specification in the optic vesicle caused anophthalmia in mice. By achieving this early and tissue-specific beta-catenin inactivation we find that retinal pigment epithelium (RPE) commitment was blocked and eye development was arrested prior to optic cup formation due to a loss of canonical Wnt signalling in the dorsal optic vesicle. Thus, these results show that Wnt/beta-catenin signalling is required earlier and play a more central role in eye development than previous studies have indicated. In our genetic model system a few RPE cells could escape beta-catenin inactivation leading to the formation of a small optic rudiment. The optic rudiment contained several neural retinal cell classes surrounded by an RPE. Unlike the RPE cells, the neural retinal cells could be beta-catenin- negative revealing that differentiation of the neural retinal cell classes is beta-catenin-independent. Moreover, although dorsoventral patterning is initiated in the mutant optic vesicle, the neural retinal cells in the optic rudiment displayed almost exclusively ventral identity. Thus, beta-catenin is required for optic cup formation, commitment to RPE cells and maintenance of dorsal identity of the retina