ABSTRACT
Titanium diffusion from (001) SrTiO3 (STO) substrates into CoFe2O4 (CFO) films grown using pulsed laser deposition is reported. To elucidate the reasons for Ti interdiffusion, a comparative study of CFO films grown on MgAl2O4 (MAO) and STO substrates, buffered by thin STO and MAO layers, has been made. It is shown that whereas bottom STO layers always result in Ti migration, a thin MAO layer, only 8 nm thick, is effective in blocking it. We argue that this success relies on the lower mobility of Ti ions in the MAO lattice compared to that of CFO. This result should contribute to the development of high quality epitaxial heterostructures of dissimilar complex oxides.
ABSTRACT
Reflectance versus incidence angle measurements have been performed from 5 to 152 nm on samples of SiC with a different C/Si ratio deposited with rf magnetron sputtering. The optical constants of the material at different wavelengths have been determined by using a curve-fitting technique of reflectance values versus incidence angle. Complementary measurements of the incident beam polarization, film thickness, surface roughness, and stoichiometry were performed to complete the analysis of the samples.
ABSTRACT
The differentiation and morphogenesis of neural tissues involves a diversity of interactions between neural cells and their environment. Many potentially important interactions occur with the extracellular matrix (ECM), a complex association of extracellular molecules organised into aggregates and polymers. The large modular glycoprotein, Tenascin-C, and the chondroitin sulphate proteoglycan, DSD-1-PG/Phosphacan, have complex and frequently overlapping expression patterns in the developing CNS. Their presence in zones of cell proliferation, migration, and differentiation, as well as in boundary structures, suggest that they may be involved in the modulation of an extensive range of cellular processes. They are both strongly up-regulated in a range of CNS lesions and pathologies, being components of the glial scar, and expressed by gliomas. Functional roles in many cellular processes are possible through their extensive molecular interaction sites, both with each other, and with many of the same cell surface receptors, adhesion molecules, growth factors and other matrix proteins. These multiple interactions involve sites on both their protein domains and on the heterogeneous carbohydrate groups with which they are post-translationally modified. In vitro assays demonstrate cell-type specific effects on adhesion, migration and the formation and extension of cellular processes, including neurites and axons.
