Deposition of Zinc Oxide on the Materials Used in Medicine. Preliminary Results

This paper presents preliminary results of the direct deposition of nano- and microstructures of zinc oxide on materials used in medicine. The coatings were deposited on cotton gauze and polyamide fabric. During the research the biological activity of these materials was defined. Performed were also tests of doping the ZnO structures with silver obtained. The research has proved that there is a growth of zinc oxide structures both on the gauze and polyamide fabric. The nanostructures deposited on it did not become detached from the surface, even though the material was subjected to ultrasonic rinsing. In addition, good biocidal properties of both of the textile materials modified were found. Furthermore a complex surface analysis of catheters: vascular and urological was made. ZnO was deposited on catheters, but they were characterised by low adhesion

Correlation between Microstructure and Chemical Composition of Zinc Oxide Gas Sensor Layers and Their Gas-Sensitive Properties in Chlorine Atmosphere

In this article, we present results concerning the impact of structural and chemical properties of zinc oxide in various morphological forms and its gas-sensitive properties, tested in an atmosphere containing a very aggressive gas such as chlorine. The aim of this research was to understand the mechanism of chlorine detection using a resistive gas sensor with an active layer made of zinc oxide with a different structure and morphology. Two types of ZnO sensor layers obtained by two different technological methods were used in sensor construction. Their morphology, crystal structure, specific surface area, porosity, surface chemistry and structural defects were characterized, and then compared with gas-sensitive properties in a chlorine-containing atmosphere. To achieve this goal, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL) methods were used. The sensing properties of obtained active layers were tested by the temperature stimulated conductance method (TSC). We have noticed that their response in a chlorine atmosphere is not determined by the size of the specific surface or porosity. The obtained results showed that the structural defects of ZnO crystals play the most important role in chlorine detection. We demonstrated that Cl2 adsorption is a concurrent process to oxygen adsorption. Both of them occur on the same active species (oxygen vacancies). Their concentration is higher on the side planes of the zinc oxide crystal than the others. Additionally, ZnO sublimation process plays an important role in the chlorine detection mechanism

Protein-Mediated Precipitation of Calcium Carbonate

Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein

Influence of stabilising agents and pH on the size of SnO2 nanoparticles

According to recent research, the use of nanoparticles as a gas-sensitive material increases the selectivity and sensitivity and shortens the response time of a sensor. However, the synthesis of SnO2 nanoparticles presents many difficulties. The following article presents a simple and inexpensive method for the synthesis of SnO2 nanoparticles. The influence of the surfactant and polymer choice on the size of the resulting nanoparticles was investigated and a mechanism describing their interaction was proposed. It was found that stable colloids of SnO2 nanoparticles are formed in the presence of both PEI and Triton X-100 surfactants as stabilising agents. However, an additional factor essential for good stabilisation of the nanoparticles was an appropriate acidity level of the solution. Under optimal conditions, nanoparticles having an average diameter of about 10 nm are reproducibly formed

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

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

Concentration-Dependent Emission of Annealed Sol-Gel Layers Incorporated with Rhodamine 19 and 6G as the Route to Tunable High-Temperature Luminescent Materials

The sol-gel technology allows for the development of materials for nonlinear optics and photonics through the synthesis of multifunctional ceramic materials. Although the nature of the amorphous matrix allows the material to be doped with a large amount of the active components without quenching, it may affect the spectroscopic characteristics of the dye (e.g., result in a shift of absorption and emission peaks with drying time, presumably with a change of concentration). This study presents the material (SiO2 impregnated with organic dyes—Rhodamine 6G and 19) with tunable emissions obtained by the authors upon annealing at different temperatures within the range of 100–300 °C. Possible observed effects were discussed based on spectroscopic properties and thermal studies of the synthesized material. Concerning annealing at different temperatures, an effect on concentration was observed. At the same time, a longer heating process at 300 °C revealed a protective function of sol-gel-derived silica for the organic dye; the longer heating did not cause any further significant changes in the dye’s emission, which indicates the preservative role of the sol-gel layers. Furthermore, etching tests of thin layers were conducted, resulting in smooth side edges of the waveguide. The tests have shown that it is possible to use dye-doped sol-gel layers as active components in photonics platforms

Multifunctional Nanocomposite Cellulose Fibers Doped in Situ with Silver Nanoparticles

This paper presents a method for the preparation of nanocomposite cellulose fibers doped with silver nanoparticles (AgNPs), as well as the effect of silver nanoparticles on the structure and properties of fibers. The fibers were obtained by an environmentally friendly method using N-Methylmorpholine N-oxide (NMMO) as a solvent, in a non-polluting closed system. Doping with silver nanoparticles was carried out as a direct (in situ) reduction of Ag+ ions in the presence of a stabilizing agent during the preparation of the spinning solution. SEM images of the surface and cross section of the fibers showed that the distribution of nanoparticles in the fibers’ volume was uniform. The fibers exhibited very good antibacterial properties in relation to Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, and Candida albicans. Flammability analysis showed that the fibers were subjected to a one-stage combustion process and that the silver nanoparticles reduced the heat release rate (HRR) of the fibers by 36%. TG studies showed that the modification of cellulose fibers with silver nanoparticles promoted the formation of mill scale in the combustion of fibers, which was directly related to the reduction of flammability. Tests of the electrical properties showed that the linear resistance of cellulose fibers containing 3 wt % silver was 108 Ω/cm