Niobium coatings deposited by magnetron sputtering were evaluated as a possible surface modification for stainless steel (SS) substrates in biomedical implants. The Nb coatings were deposited on 15 mm diameter stainless steel substrates having an average surface roughness of 2 µm. To evaluate the biocompatibility of the coatings three different in vitro tests, using human alveolar bone derived cells, were performed: cellular adhesion, proliferation and viability. Stainless steel substrates and tissue culture plastic were also studied, in order to give comparative information. No toxic response was observed for any of the surfaces, indicating that the Nb coatings act as a biocompatible, bioinert material. Cell morphology was also studied by immune-fluorescence and the results confirmed the healthy state of the cells on the Nb surface. X-ray diffraction analysis of the coating shows that the film is polycrystalline with a body centered cubic structure. The surface composition and corrosion resistance of both the substrate and the Nb coating were also studied by X-ray photoelectron spectroscopy and potentiodynamic tests. Water contact angle measurements showed that the Nb surface is more hydrophobic than the SS substrate. OPEN ACCESSCoatings 2011, 1 73

Under Mediterranean climates with dry-hot summers and cool-wet winters, many forbs with potential for habitat restoration are winter annuals, but there is little information about their germination. We performed laboratory germination experiments on 13 ruderal dicots native to Andalusia (southern Spain). We measured the germination of recently harvested seeds from natural populations across nine temperature treatments (from 5 to 35 °C, constant and alternate); two storage periods; and eight water stress treatments (from 0 to -1.0 MPa). We then calculated the hydrothermal thresholds for seed germination. Final germination ranged from 0-100% and results were mixed in response to temperature. Base temperature was below 6 °C, optimal temperature was around 14 °C and the ceiling temperature around 23 °C. For five species, 10 months of storage improved total germination, indicating a dormancy-breaking effect, but the other species did not respond or had their germination reduced. All species were relatively tolerant to water stress, with base water potential ranging from -0.8 to -1.8 MPa. Our results suggest that hydrothermal germination thresholds, rather than physiological dormancy, are the main drivers of germination phenology in annual forbs from Mediterranean semi-dry environments. The variation in germination responses of these forb species differs from winter annual grasses, but their seeds are all suitable for being stored before restoration.

Abstract-In order to obtain novel polymers having a very high chromophore density, dipropargyloxy benzoic acids converted to benzoates containing an azo dye, Disperse Red 1, were synthesized and characterized. 2,6-Dipropargyloxy benzoic acid could not be obtained. The bisacetylenic monomers were then polymerized by oxidative coupling reaction. Amorphous polymers with an inherent viscosity of around 0.3 in N-methylpyrrolidone (NMP) were obtained. The polymers were soluble in polar solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. The solutions in DMF caused precipitation due to the agglomeration of the dye groups on standing for a few days, but the precipitated polymers became soluble again in NMP. The UV irradiation on the spin-coated lms at 80 ± C cross-linked the lms to convert them to thermoset resin lms.

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The aim of this study was to evaluate the effect of polyol and chitosan (CS) incorporation within polyurethanes (PUs) and their resulting thermal stability, hardness, swelling behaviour, in vitro degradation, and cell viability to establish the potential for these materials in biomedical applications. CO (CO) was modified by a transesterification reaction with pentaerythritol. Original CO and modified CO, isophorone diisocyanate (IPDI) in a NCO/OH equal to 1, CS were used for PU synthesis. PUs were characterized by FTIR, hydroxyl value (ASTM D1957), thermogravimetric analysis, and Shore A hardness (ASTM D2240). The contact angle and swelling assay with PBS was carried out to study the hydrophilic character. Assays at 37°C and 105°C assessed in vitro degradation. Finally, the cell viability of a L-929 mouse embryo fibroblast was performed on solid polymers and degradation products. The hydroxyl value confirms CO modification, and IR analysis confirms CS incorporation into the matrix. The thermal assay does not show that new degradation stages and polyol, with a high functionality, had better mechanicals results due to the increase in crosslinking. The contact angle shows the hydrophobic surface with an angle over 65°, and the CS and polyol