The aim of this study was to investigate of the efficacy and reliability of a novel antimicrobial hydroxyapatite (HA) nanoparticle coating of urethral catheters, in the prophylaxis of biofilm formation and bacteriuria in rabbits. A total of 60 male rabbits were randomized to the control and study groups and each group was divided into three subgroups depending on 3, 5 and 7 days of the urethral catheterization period. The rabbits in the study group were catheterized with Ag(+)-incorporated nano-HA coated urethral catheters and those in the control group with standard silicon-latex urethral catheters. Urine and catheter surface smear samples were conducted for bacteriological analysis. Catheter cross-section samples were undergone measuring of biofilm thickness. Tissue samples of bladder and urethra were inspected for histological changes. The results indicate that at the end of 7 days of the catheterization period, the number of the rabbits with bacteriuria was significantly lower in the study group versus control group (p (¶) = 0.020). The biofilm formation on luminal surface of the catheters was significantly thinner in the study group versus control group, at the end of 5 and 7 days of the catheterization period (0.035 and 0.035, respectively).No histological adverse change or particle penetration was detected in the urothelium. In conclusion, it was observed that Ag(+) + HA nanoparticle coating significantly lowered the incidence of catheter-related bacteriuria and decreased biofilm formation, at the end of 7 days study period. The novel antimicrobial urethral catheter coating appeared to have a potential in the prophylaxis of catheter-induced urinary tract infections.
Microstructural characterization of corn starch-based porous thermoplastic (TPS) composites containing various contents (0.1, 0.5, and 1 wt %) of multiwalled carbon nanotubes (MWCNTs) was performed. Corn starch was plasticized with a proper combination of glycerol and stearic acid. TPS composites with MWCNT were prepared conducting melt extrusion followed by injection molding. TPS containing 1 wt % of MWCNTs exhibited higher tensile strength and elastic modulus values than neat TPS. Moreover, TPS electrical conductivity was determined to increase with increasing content of MWCNTs. X-ray diffraction measurements revealed that incorporation of MWCNTs increased the degree of TPS crsystallinity to some extent. Scanning electron microscopy examination revealed that MWCNT altered TPS surface morphology and tensile failure modes, significantly. Transmission electron microscopy investigation showed that dispersion characteristics of MWCNTs within TPS were in the form of tiny clusters around micro pores of TPS, which is considered influential on electrical conductivity of the resulting composites.
Poly(ether ester) (PEE) copolymers were synthesized in a two-stage process involving transesterification and polycondensation. The synthesized copolymer and the zinc oxide (ZnO) were used in composite preparation by melt compounding. The influence of ZnO type and concentration on the morphology, thermal and mechanical properties of the composites were studied. DSC and XRD analyses indicated that crystallinity of composites was slightly reduced with ZnO content. Homogeneous dispersion of fillers in the polymer matrix was observed through morphological analyses. While in general tensile strength and elongation at break values of the composites decreased with increasing ZnO content, elastic modulus values increased with the addition of ZnO. Moreover, ZnO particles were modified with poly(N-vinyl pyrrolidone) and a slight improvement in mechanical properties was observed, respectively over the composites containing unmodified particles.
In this study, flax fiber char (CH), a kind of biomass carbon material obtained by thermochemical conversion of flax fibers in a nitrogen environment in a fixed bed reactor, was used as a reinforcing constituent together with carbon fiber (CF) to produce polyamide 66 (PA66) hybrid composites. The potential use of biochar as a promising substitutional filler candidate for CF in composite applications was deemed in principle. Biochar and carbon fiber surfaces were treated with nitric acid followed by modification with a 3-aminopropyltriethoxysilane coupling agent to improve their interfacial compatibility with PA66. The overall characterization of the composite materials was conducted by performing the thermal gravimetric analysis and differential scanning calorimetry measurements and tensile and water absorption tests. Scanning electron microscopy was further employed to examine the fracture surface of the specimens. The findings obtained revealed that silane -modified CF and CH altered composite material crystallization behavior, thus enhancing the ultimate composite tensile strength and Young's modulus. Moreover, the tailored interfacial interactions associated with enhanced thermal stability were determined to reduce water absorption capacity for composites with CH. In brief, CH may be substituted with CF, costeffectively, at a 50:50 w/w ratio of total reinforcement (10 wt%) in PA66 without compromising ultimate composite performance.
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