Laser based hybrid techniques for surface coatings

Laser beam build-up welding gains increasing importance for the production of high-performance coatings for applications in surface treatment and remanufacturing. However, the cladding rate is low and the specific running costs are comparatively high, so that potential laser applications remain undeveloped first of all for economical reasons. Against this background, innovative developments aim at combining laser build-up welding and efficient spraying, welding, and heat treating techniques. For large area claddings, laser assisted plasma spraying guarantees as a one-step coating process high deposition rates, completely dense coatings and a strong, metallurgical bonding to the substrate. Furthermore, the sequential combination of laser and plasma build up welding (PTA) is a promising variant for the production of precision parts. Here, the laser beam generates the outer contours of filigree and complex shape, and the plasma gun fills efficiently the inner volume. Finally, the combinat ion of laser cladding and simultaneous induction heating is a solution for the production of up to 65 HRC hard and crack-free metal coatings or composite claddings containing up to 75 % carbide particles. The welding speed reaches up to 10m/min. Examples of application are ceramic coatings on turbine blades, nickel-base coatings on metal forming tools, and repaired tools and molds

Erarbeitung von Kriterien fuer die Beurteilung des Umweltrisikos durch potentiell wassergefaehrdende Pflanzenschutzmittel - aquatische Modelloekosysteme im Freiland

SIGLETIB Hannover: RN 8908(89-136) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Heparin desulfation modulates VEGF release and angiogenesis in diabetic wounds

While vascular endothelial growth factor (VEGF) has been shown to be one of the key players in wound healing by promoting angiogenesis current clinical applications of this growth factor to the wound environment are poorly controlled and not sustainable. Hydrogels made of sulfated glycosaminoglycans (GAG) allow for the sustained release of growth factors since GAGs engage in electrostatic complexation of biomolecules. In here, we explore a set of hydrogels formed of selectively desulfated heparin derivatives and star-shaped poly(ethylene glycol) with respect to VEGF binding and release and anticoagulant activity. As a proof of concept, supportive effects on migration and tube formation of human umbilical vein endothelial cells were studied in vitro and the promotion of wound healing was followed in genetically diabetic (db/db) mice. Our data demonstrate that the release of VEGF from the hydrogels is modulated in dependence on the GAG sulfation pattern. Hydrogels with low sulfate content (11% of initial heparin) were found to be superior in efficacy of VEGF administration, low anticoagulant activity and promotion of angiogenesis. (C) 2015 Elsevier B.V. All rights reserved