This work examines the effect of selected process parameters on the diameter of uniform and heterogeneous fibers (with and without bead-on-string structures) and the size of beads obtained during the electrospinning process. A 23 factorial design was performed to determine the influence of the following factors: electrical voltage, flow rate and dynamic viscosity of the poly(vinylpyrrolidone) ethanolic solution. Factorial design enables the analysis of the mathematical relationship between the chosen factors and the response with a minimum number of experiments. The factor having the most significant impact on the size of beaded fibers and beads was the solution viscosity, while the voltage had the greatest influence on the bead-free fiber diameter. The interactions between the studied factors were also analyzed. It was found that the presented method can be used for the design of an optimal and cost-effective electrospinning process, allowing the desired product to be obtained with expected features.

Triply periodic minimal surfaces (TPMS) are known for their advanced mechanical properties and are wrinkle-free with a smooth local topology. These surfaces provide suitable conditions for cell attachment and proliferation. In this study, the in vitro osteoinductive and antibacterial properties of scaffolds with different minimal pore diameters and architectures were investigated. For the first time, scaffolds with TPMS architecture were treated electrochemically by plasma electrolytic oxidation (PEO) with and without silver nanoparticles (AgNPs) to enhance the surface bioactivity. It was found that the scaffold architecture had a greater impact on the osteoblast cell activity than the pore size. Through control of the architecture type, the collagen production by osteoblast cells increased by 18.9% and by 43.0% in the case of additional surface PEO bioactivation. The manufactured scaffolds demonstrated an extremely low quasi-elastic modulus (comparable with trabecular and cortical bone), which was 5 -10 times lower than that of bulk titanium (6.4-11.4 GPa vs 100-105 GPa). The AgNPs provided antibacterial properties against both gram-positive and gram-negative bacteria and had no significant impact on the osteoblast cell growth. Complex experimental results show the in vitro effectiveness of the PEO-modified TPMS architecture, which could positively impact the clinical applications of porous bioactive implants.

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In the years 2001-2015, 42 rockbursts were recorded in Polish coal mines. For the past 15 years the scale of the phenomena has been similar and ranges from 1 to 5 rockbursts per year. However, the number of recorded high energy seismic tremors of 108 and 109J (E) energy that has occurred in recent years, 2 to 5, is alarming. According to the data, 27 of tremors of E > 108 J energy that occurred between 2001 and 2015 caused 3 rockbursts. Confronting these data with seismic activity from 1989-2000, it should be noted that only 2 events out of 99 rockbursts caused tremors with energies of E>108 J. Against the background of the scale of seismic and rockburst hazards, the geological and mining conditions of the Upper Silesian Coal Basin (USCB) have been analysed, detailing the structural units in which the rockbursts occurred. On this basis, the author characterised factors that impacts on the mining excavations resulting in rockbursts that caused damage on a larger scale. These rockbursts had the characteristics of mining catastrophes and weak earthquakes not recorded in mining statistics of natural hazards of USCB so far.

The static and dynamic reserve of voltage in input of voltage autonomous inverter being a component of parallel power active compensator on the physical realizability of inactive current components with the determined response, pulsations amplitude and commutation frequency of invertor switches was considered. Invariance of closed system of automated power quality regulation with relay control to the parametric and external disturbances is provided by the dynamic voltage reserve calculated from the obtained expressions. Special attention is given to the possibility of using this system in mining. Proposed approaches also can be used in the training of engineers in the electrical and mining industries.

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3D bioprinting uses bioink deposited directly on a collector to create any previously designed 3D model. One of the most common and the easiest to operate bioinks is gelatin-alginate hydrogel....