Search

Summary: Objectives: To evaluate the efficacy in vitro and in vivo of a new antibacterial suture (PGAB) compared with a traditional braided suture (PG). Our primary goals were to study microbiological effectiveness and impact on wound healing of PGAB vs PG. Secondary goal was to analyze influence on inflammatory response. Methods: In vitro study: clinical samples of Staphylococcus epidermidis, Staphylococcus aureus, S. hominis, Staphylococcus haemolyticus, Staphylococcus auricularis, Enterococcus faecalis, Corynebacterium spp. and Escherichia coli were studied. We also implanted a flat mesh in 10 minipigs, four incisions each (two PG and two PGAB) two contaminated with S. epidermidis and two not contaminated. Finally, we performed four colic anastomosis in each of 10 minipigs, two contaminated with E. coli and two not contaminated (two PG and two PGAB). We studied the inflammatory and wound healing processes in both models. Results: We observed a bactericidal efficacy of PGAB against grampositive, and bacteriostatic effect against E. coli. Mesh study: recovered CFU were lower in the group PGAB vs PG. In the group PGAB, inflammatory mediators'' concentrations were lower. In the group PGAB, concentrations of wound healing mediators were normal. Colic anastomosis: recovered CFU were lower in the group PGAB vs the group PG. In the group PGAB we observed a reduction of inflammatory mediators. In the group PGAB we observed normalized concentrations of wound healing mediators. Conclusions: This study demonstrates microbiological efficacy of PGAB, that normalizes wound healing process, and an anti-inflammatory effect. [Copyright &y& Elsevier]

In this study, the viability of obtaining potassium hexatitanate fibers (K 2 Ti 6 O 13 ) via the flux method using boric acid subjected to different melting temperatures and cooling media (air or water) was investigated. According to the results, the amount of used flux enabled the production of a liquid phase in which the TiO 2 and K 2 O reacted to form K 2 Ti 6 O 13 with various morphologies. The melting temperature did not significantly influence the microstructure presented by the materials; however, an amorphous phase with small crystals was obtained when molten mixtures were poured into water in comparison with the samples cooled with air. With the goal of obtaining homogeneous fibers, the samples with lower crystallinity (poured into water) were heated at 900, 950 and 1000 °C. Fibers were produced with sizes varying from 12 to 35 μm in length and 0.51–0.90 μm in diameter as well as with a large specific surface area and a band gap value of 3.3 eV; these characteristics make these fibers promising for use as photocatalysts. [ABSTRACT FROM AUTHOR]

Aluminum matrix composites (AMCs) are candidate materials for aerospace and automotive industry owing to their large elastic modulus, improved strength and low wear rate. A simple method for fabrication of Al7075–graphite composites produced by mechanical alloying (MI) and hot extrusion is described in this paper. Effects of milling time (0–10 h) and graphite concentration (0–1.5 wt.%) on friction, hardness and wear resistance of the AMC were investigated. Wear resistance was determined by the pin-on-disk wear method using 20 and 40 N normal loads at a 0.367 m/s sliding velocity. The worn surfaces were examined by scanning electron microscopy (SEM) to identify distinct topographical features for elucidation of the prevailing wear mechanisms. Experimental results indicated considerable improvement in AMC hardness and wear resistance by adding 1.5% G (wt.) and 10 h of milling, showing homogenous distribution of the reinforcement particles in the Al-base metal-matrix composite. It was found that abrasion is the dominant wear mechanism in all extruded composites, whilst a combination of adhesion and delamination seems to be the governing mechanism for the 7075 aluminum alloy. [ABSTRACT FROM AUTHOR]

Highlights: [•] Al7075–graphite composites were fabricated by mechanical alloying and hot extrusion. [•] Mechanical properties are enhanced as function of graphite content and milling time. [•] The strengthening is due to grain refining, Al4C3 and increased dislocation density. [ABSTRACT FROM AUTHOR]