Olga Rac

Deposition of one-dimensional zinc oxide structures on polypropylene fabrics and their antibacterial properties

In this article, a new method of modification of polypropylene fabric surface is presented, in order to obtain a material with antibacterial properties. The surface of the fabric is modified by direct deposition of the hexagonal zinc oxide rods onto the surface. For this reason, the influence of temperature on the size and morphology of microstructures of ZnO was investigated. Deposition was carried out at two temperatures, 75 and 90℃. The surface of the fabrics was treated with oxygen plasma. The influence of oxygen plasma on the parameters of rods was examined. The microstructure and crystalline structure of ZnO rods were investigated by scanning electron microscopy and X-ray diffraction. In addition, the impact of morphology and size of obtained ZnO structures on the biological activity of modified materials was determined. The tests revealed that the modified fabric shows very good antibacterial activity.

Analysis of SnO2|WO3 Heterocontact Properties during the Detection of Hydrogen Sulphide

The main objective of the paper was the analysis of the properties of SnO2|WO3 heterocontact as well as the determination of its response to 50 ppm of hydrogen sulphide. It was noticed that the sensitivity of the sensor being tested to hydrogen sulphide depended significantly on the polarization direction. When its parameters were compared with those of sensors the gas-sensitive layer of which was made only from one type of metal oxide, a high impact of the heterocontact on the electric charge transport was noticed. The value of the activation energy of the electric conductivity is clearly dependent on the polarization direction. A mechanism of physicochemical processes occurring in a planar sensor with a heterocontact was suggested, and three areas differing in the width of depleted layer, where the inter-phase boundary of SnO2|WO3 had the most essential impact on the parameters of the sensor being tested, were distinguished and described.

Application of gold nanoparticles of different concentrations to improve the therapeutic potential of autologous conditioned serum: potential implications for equine regenerative medicine

The aim of this work was to evaluate the effect of different concentrations of gold nanoparticles (AuNPS) on equine platelet morphology, ultrastructure as well as secretion of bone morphogenetic protein 2 (BMP-2), vascular endothelial growth factor (VEGF), gelsolin (GSN), and tumor necrosis factor alpha (TNF-α). The gold nanoparticles, with an average diameter of 20 nm, were incubated with whole anticoagulated blood at 1%, 5%, and 10% w/v for 24 hours. We showed that the application of gold nanoparticles at all the tested concentrations led to platelet activation; however, 5% of AuNPS resulted in the secretion of elevated levels of GSN and VEGF, while the concentration of TNF-α was the lowest. The data indicate that this method may be considered a promising tool for improving the currently used in clinical practice commercially available autologous conditioned serum (ACS) isolation systems for the treatment of equine osteoarthritis.

Chlorine sensing properties of zinc oxide resistive gas sensor doped with platinum

In presented studies resistive chlorine gas sensor with gas sensitive layer in the form of zinc oxide microrods doped with platinum was developed. The growth of active layer was carried out in water solution containing zinc nitrate (V), hexamethylenetetramine and chloroplatinic acid using the chemical bath deposition method. The structure and morphology of obtained sensors was characterized by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX). To determine the chlorine gas sensing properties Temperature-Stimulated Conductance method (TSC) was used. During the measurements sensor was tested in a reference atmosphere and an atmosphere with 2, 5 or 8 ppm of chlorine. Obtained results have shown that zinc oxide microrods doped with platinum were obtained. TSC measurements showed that developed sensor allows to detect chlorine with very good sensitivity.

Synthesis of zinc oxide nanospheres

We present a method for the synthesis of monodispersive ZnO colloidal spheres. The colloidal spheres are made from the solution of zinc acetate and polyethylene glycol (PEG) in the temperature 135°C. The obtained structures were investigated with scanning electron microscope (SEM) and transmission electron microscope. The structures received in the process are spheres with diameter 300 nm-1 µm. ZnO nanospheres have plenty of possibilities of application, for example in gas sensors or as a self-assembled material in photonic crystals.

The Impact of Sepiolite on Sensor Parameters during the Detection of Low Concentrations of Alcohols

The article presents the results of the detection of low-concentration C1–C4 alcohols using a planar sensor, in which a sepiolite filter was applied next to the gas-sensitive layer based on tin dioxide. The sepiolite layer is composed of tubes that have a length of several microns, and the diameter of the single tube ranges from several to tens of nanometers. The sepiolite layer itself demonstrated no chemical activity in the presence of volatile organic compounds (VOC), and the passive filter made of this material did not modify the chemical composition of the gaseous atmosphere diffusing to the gas-sensitive layer. The test results revealed that the structural remodelling of the sepiolite that occurs under the influence of temperature, as well as the effect of the filter (a compound with ionic bonds) with molecules of water, has a significant impact on the improvement of the sensitivity of the sensor in relation to volatile organic compounds when compared to the sensor without a filter.