Evaluation of Bacterial Adhesion to the ZrO2 Atomic Layer Deposited on the Surface of Cobalt-Chromium Dental Alloy Produced by DMLS Method

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO2) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface.

Effect of ZnO and SnO2 Nanolayers at Grain Boundaries on Thermoelectric Properties of Polycrystalline Skutterudites

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO2) nanolayers at the grain boundaries of polycrystalline In0.2Yb0.1Co4Sb12 skutterudites on their electrical and thermal transport properties. Skutterudite powders with oxide nanolayers were prepared by atomic layer deposition method, and the number of deposition cycles was varied to control the coating thickness. The coated powders were consolidated by spark plasma sintering. With increasing number of deposition cycle, the electrical conductivity gradually decreased, while the Seebeck coefficient changed insignificantly; this indicates that the carrier mobility decreased due to the oxide nanolayers. In contrast, the lattice thermal conductivity increased with an increase in the number of deposition cycles, demonstrating the reduction in phonon scattering by grain boundaries owing to the oxide nanolayers. Thus, we could easily control the thermoelectric properties of skutterudite materials through adjusting the oxide nanolayer by atomic layer deposition method.

Carbon Materials for Immobilization of Biologically Active Substances

The paper considers applications of carbon materials as carriers of biologically active substances. The atomic layer deposition method allowed chemically synthesizing surface-modified composite materials based on graphite and carbon fibers, which maximally preserved the activity of enzymes and biologically active substances. It is shown that the activity of a biologically active substance depends on the chemical composition and state of the surface of carbon-based carriers.

The Effect of Aluminum Dopant Amount in Titania Film on the Memristor Electrical Properties

In a promising nanoelectronics device, namely, memristor based on metal oxides, there are many intermediate states with different conductivity between the limits of highly conductive and low-conducting states. These intermediate states can be used in the processes of associative learning of a neural network based on memristor synapses and simultaneous processing of input pulses, which consists in their weighing and summation in the neuroprocessor. By the method of simultaneous magnetron sputtering of two cathodes in a reactive oxygen environment, thin films of mixed oxides with a different mole ratio of titanium and aluminum were obtained. A method for obtaining a mixed oxide with a specified metal fractions by controlling the sputtering rates of cathodes using acoustic piezoelectric sensors is described. It is shown that the introduction of Al into titanium oxide improves the electrophysical characteristics of the memristor. The existence of an optimal fraction of Al dopant maximizing the memristor resistance ratio of the high-resistive and low-resistive states is established. The results indicate that the method of reactive magnetron deposition of mixed metal oxide by simultaneous sputtering of two cathodes provides a more uniform distribution of elements across the thickness of the active layer compared with the atomic layer deposition method. The uniform distribution is necessary to improve the stability of the memristor. It can be expected that in the memristors on mixed oxides TixSc1-xOy, HfxSc1-xOy, HfxY1-xOy, HfxLu1-xOy, ZrxSc1-xOy, ZrxY1-xOy, ZrxLu1-xOy an optimal dopant fraction corresponding to the maximally increased ratio of resistances in the high-resistance and low-resistance states will also be observed. Moreover, memristors on films with pure hafnium and zirconium oxides have a much larger range of resistive switching than titanium oxide.

An ultrathin Al2O3 bridging layer between CdS and ZnO boosts photocatalytic hydrogen production

An ultrathin Al2O3 bridging layer is intentionally introduced into the interface between CdS and ZnO by using an atomic layer deposition method, and the resultant CdS@Al2O3@ZnO catalyst exhibits a significantly enhanced H2 evolution rate.