15 research outputs found
1st Symposium on Laser Spectroscopy : August 28-30,Pécs
New developments are reviewed concerning the surface nitr'ioation of
lx and Ti Dy Doth pulsed and cw CO2 laser irradiation in a nitrogen
atmosphere, under a layer of liquid nitrogen or in air. For each procedure as
analyzed tne relative advantages and tne main limitatians are indicated
together with further possiole solutions and improvements
Abandonment of crop lands leads to different recovery patterns for ant and plant communities in Eastern Europe
Significant proportion of crop lands have been abandoned as management strategies have changed in Central and Eastern Europe in the past decades. The study of insect versus plant communities in such areas could help us understand how these processes take place, and whether these communities return to a semi-natural state maintained by human activities. Amongst insects ants, as ecosystem engineers, are a perfect target group in this respect. We studied epigaeic ant and plant communities of abandoned old-fields in Romania. Contrary to our expectations, the total number of ant species did not increase with time during succession on old-fields contrary to plants, where an increase was registered in the total number. Disturbancetolerant ant species dominated the ant communities throughout the successional gradient, while in the case of plants a transition was found from weed-dominated to semi-natural communities. The diversity of both ant and plant communities increased after the 1-year stage, but the patterns were different. While a return to semi-natural state could be observed in plants during old-field succession, such a definite change did not occur in ants. This might be caused by the landscape context: the lack of connectivity of old-fields to larger natural areas. While plant propagules of semi-natural and natural habitat species can still successfully colonize the old fields even under such conditions, ant colonizers are mainly disturbance-tolerant species typical for agricultural areas, which can be hardly replaced by typical grassland species. Our findings underline the existence of important discrepancies between plant and ant community succession, mostly treated as paralleling each other. This is the first study to handle the effect of abandonment on ant and plant communities simultaneously in Eastern Europe
A novel cyclic RGD-containing peptide polymer improves serum-free adhesion of adipose tissue-derived mesenchymal stem cells to bone implant surfaces
Seeding of bone implants with mesenchymal
stem cells (MSCs) may promote osseointegration and bone
regeneration. However, implant material surfaces, such as
titanium or bovine bone mineral, fail to support rapid and
efficient attachment of MSCs, especially under serum-free
conditions that may be desirable when human applications
or tightly controlled experiments are envisioned. Here we
demonstrate that a branched poly[Lys(Ser
i
-DL-Ala
m
) polymer functionalized with cyclic arginyl-glycyl-aspar-
tate, when immobilized by simple adsorption to tissue
culture plastic, surgical titanium alloy (Ti6Al4V), or Bio-
Oss
bovine bone substitute, significantly accelerates
serum-free adhesion and enhances seeding efficiency of
human adipose tissue-derived MSCs. Moreover, when
exposed to serum-containing osteogenic medium, MSCs
survived and differentiated on the peptide-coated scaffolds.
In summary, the presented novel polypeptide conjugate can
be conveniently used for coating various surfaces, and may
find applications whenever quick and efficient seeding of
MSCs is required to various scaffolds in the absence of
serum