Characterization of polypropylene/magnesium oxide/vapor-grown carbon fiber composites prepared by melt compounding

In this paper, we discussed the characteristics and properties of polypropylene (PP)/magnesium oxide (MgO) composites prepared by melt compounding. In addition, we also discussed the effect of adding vapor-grown carbon fiber (VGCF) to PP/MgO composite on the properties of the composites. The thermal conductivity of PP/MgO increased with MgO content. In the region of MgO content of more than 30 vol%, the thermal conductivity of PP/MgO with MgO-10 (particle size of 10 μm) is the largest by comparison of other PP/MgO with different MgO sizes. The thermal conductivity of PP/MgO became increased by adding VGCF in PP/MgO. According to the estimation of thermal conductivity using Bruggeman’s equation, no synergistic effect was observed by adding VGCF into the PP/MgO composite. The surface resistance of PP/MgO significantly decreased by adding VGCF at a content of more than 3 vol%. At VGCF content of 1 vol%, the surface resistance of the composite became large, and the value was more than 109 Ω/sq. In addition, the Non-Newtonian property of PP/MgO composite melt was enhanced by the addition of VGCF into the composite.

EXPERIMENTAL STUDY OF ANTIBACTERIAL DRUGS ON PSEUDOMONAS AERUGINOSA BIOFILMS

The article presents the results of stages of biofilm formation and sensitivity to antibacterial drugs of Pseudomonas aeruginosa bacteria. The technique for preparation of drugs for investigation in an optical and scanning electron microscope has been developed, which allows one to consistently study populations of Pseudomonas aeruginosa bacteria without disturbing natural architectonics. The culture of gram-negative bacteria Pseudomonas aeruginosa №17 in the logarithmic growth phase of growth was used in the work. A solution of canned bile of cattle and pigs, antibiotics of different groups and disinfectants were used as antibacterial preparations. To study the morphology of the P. aeruginosa population, the preparations were fixed in vapor of 25% (by DW) solution of glutaraldehyde. For staining, pairs of a 1% aqueous solution of osmic acid (OSO4) were used, dehydrated with propylene oxide vapor. The action of antibacterial drugs of various groups were studied in the population of P. aeruginosa. Studying the sensitivity of bacteria by diffusion to agar using standard commercial discs, it was found that P. aeruginosa is sensitive to the β-lactam antibiotic group, aminoglycosides, quinolones. Experimental data on the study of the effect of antibacterial drugs on processes of biofilm formation expand the boundaries of knowledge in the field of reseaches of the adaptive capabilities of ubiquitous bacteria for long persistence in both the warm-blooded organism and in environmental objects.