ABSTRACT
We report on continuous-wave (cw) laser experiments with a high-quality and large-size Yb:Lu2O3 polycrystalline transparent ceramic in a thin-disk laser oscillator. An output power of up to 1190â W was achieved in multimode operation with an optical efficiency of 60.3%. In fundamental-mode operation, a cw output power of 409â W was extracted with an optical efficiency of 35.6% and a beam propagation factor of M2 = 1.11.
ABSTRACT
Step-index fibers (SIFs) with alumina cores were fabricated employing the powder-in-tube technique. The fabricated SIFs have alumina concentrations of up to 32 mol%, which is the highest value reported so far for fibers with core diameters smaller than 25 µm. The mixing mechanisms between alumina and silica during fiber drawing were revealed by energy dispersive X-ray analysis of the neck-down area of the preform. The results of the measurements and simulations indicate that besides diffusion, fluid dynamics between softened silica and alumina powder also play an important role in the resulting alumina and silica concentrations in the fiber. The influence of different drawing parameters on the alumina and silica concentrations of the fibers is also presented.
ABSTRACT
Bacterial cellulose (BC) hydrogels are among the most efficient materials already being used for the treatment of complex wounds. The moist environment provided by the BC dressing is a key feature assuring efficient wound recovery. Improving the dressings´ moisture-holding ability facilitates its application and leads to an economically preferable extended wear time. To produce materials with reduced moisture loss, BC dressings were impregnated with a secondary hydrophilic component: alginate. The feasibility of an industrial fabrication of this composite was evaluated on pilot scale equipment. It was shown that the procedure can easily be scaled up without significantly increasing the manufacturing time. The resultant composite possessed improved water-retention properties, providing a smooth dressing exchange as demonstrated by a wound-imitating model. The new materials were moreover shown to be compatible with an antimicrobially active compound, which assures their efficiency in the treatment of highly colonized wounds.
Subject(s)
Alginates/chemistry , Anti-Bacterial Agents/chemistry , Bacteria/chemistry , Bandages , Cellulose/chemistry , Cell Line, Transformed , Humans , Materials TestingABSTRACT
Bacterial cellulose (BC) has a broad range of applications in biomedical fields and cosmetics. Applied as wound dressing, BC tends to stick to the sore especially upon drying, and hydrophobization improves its performance in this regard. This article reports a facile and rapid yet a highly efficient approach for BC hydrophobization through direct polymerization of ethyl 2-cyanoacrylate on the BC fibers. The modified material preserves the favorable porous structure of the matrix material while displaying significantly higher hydrophobicity and significantly decreased stickiness to the wound. The BC surface can be modified in 15 min. Overall, this can be considered a ready-to-apply approach for the fabrication of BC wound dressings with enhanced performance. The modification was demonstrated to improve the material's biocompatibility and to introduce antimicrobial activity (immortalized human fibroblast assay).
