Piezoelectric c-axis oriented zinc oxide (ZnO) thin films, from 1.8 up to 6.6 µm thick, have been grown by radio frequency magnetron sputtering technique onto fused silica substrates. A delay line consisting in two interdigital transducers (IDTs) with wavelength λ = 80 µm was photolith-ographically implemented onto the surface of the ZnO layers. Due to the IDTs split finger con-figuration and metallization ratio (0.5), the propagation of both the fundamental, third and nineth harmonic Rayleigh waves is excited; also, three leaky surface acoustic waves (SAWs) were detected travelling at velocity close to that of the longitudinal bulk wave in SiO2. The acoustic waves propagation in ZnO/fused silica was simulated by using 2D finite-element method (FEM) tech-nique to identify the nature of the experimentally detected waves. It turned out that, in addition to the fundamental and harmonic Rayleigh waves, also high-frequency leaky surface waves are ex-cited by the harmonic wavelengths; such modes are identified as leaky-Sezawa (LS) waves under cut-off. The velocity of all the modes was found in good agreement with the theoretically calcu-lated values. The existence of a low-loss region for the Sezawa wave below the cut off was theo-retically predicted and experimentally assessed.

The electrical and optical properties of sol-gel derived aluminum-doped0 zinc oxide thin films containing 2 at.% Al were investigated considering the modifying effects of 1) increasing the sol H₂O content; and 2) thermal treatment procedure with high-temperature approach followed by an additional heat-treatment step under a reducing atmosphere. According to the results obtained via the TG-DTA analysis, FT-IR spectroscopy, X-ray diffraction technique and four-point probe resistivity measurement, it is argued that the sol hydrolysis, decomposition of the deposited gel and crystallization of grains result in grains of larger crystallite size and stronger c-axis preferred orientation with slightly less microstrain in the modified sample. The consequent morphology and grain-boundary characteristics turn out as improved conductivity, implying higher values of concentration and mobility of charge carriers. A detailed investigation on samples optical properties, in terms of analyzing their absorption and dispersion behaviors through the UV-Vis-NIR spectroscopy, support our reasoning for the increase of the mobility, and to a lesser extent, the concentration of charge carriers, while causing only a slight degradation of optical transmission. Hence, an enhanced performance as a transparent conducting film is claimed for the modified sample by comparing the figure-of-merit values.

Here, we report on ZnO nanoparticles (NPs) generated by nanosecond pulsed laser (Nd:YAG, 1064 nm) through ablation of metallic Zn target in water and air and their comparative analysis as potential nanomaterials for biomedical applications. The prepared nanomaterials were carefully characterized in terms of their structure, composition, morphology and defects. It was found that in addition to the main wurtzite ZnO phase, which is conventionally prepared and reported by others, the sample laser-generated in air also contained some amount of monoclinic zinc hydroxynitrate. Both nanomaterials were then used to modify model wound dressings based on biodegradable poly-L-lactic acid. The as-prepared model dressings were tested as biomedical materials with bactericidal properties towards S. aureus and E. coli strains. The advantages of the NPs prepared in air over their counterparts generated in water found in this work are discussed.

In the symptomatic treatment of gastrointestinal disorders, high dosages of zinc oxide (ZnO) were conventionally employed. However, concerns regarding the potential for microbial resistance and ecological detriment have arisen due to the excessive application of this compound. These concerns highlight the urgency to minimize the use of ZnO and to explore sustainable nutritional solutions. Hydrolysable tannins (HTs), known for their role in traditional medicine for acute gastrointestinal issues, emerge as a promising alternative. This study examined the combined effect of food-grade HTs and lower ZnO concentration on relevant biological functions of Caco-2 cells, a widely used model of the intestinal epithelial barrier. We found that, when used together, ZnO and HTs (ZnO/HTs) enhanced tissue repair and improved epithelial barrier function, normalizing the expression and functional organization of tight junction proteins. Finally, the ZnO/HTs combination strengthened enterocyte defence against oxidative stress induced by inflammation stimuli. In conclusion, combining ZnO and HTs may offer a suitable and practical approach for decreasing ZnO levels in veterinary medical applications.

In this work, we report on the first attempt using size-controlled ZnO nanoparticles (NPs) to analyze role of thioacetamide (TAA) in forming ZnS nanostructures from ZnO. The size-controlled B(blue)_, G(green)_, Y(yellow)_ZnO QDs, and NC (nanocrystalline)_ZnO NPs were synthesized by sol-gel process as well as hydrothermal method, respectively and then reacted with an ethanolic TAA solution as sulfur source. After reacting with TAA, the formation of ZnS QDs was observed over time. The chemical reactions were identified using X-ray diffraction (XRD), Transmission Electron Microscope (TEM), UV-vis spectroscopy, and Photoluminescence (PL). All results indicate that ZnS formation is due to direct crystal growth and/or chemical conversion of ZnO to ZnS. Our results enable a broader understanding of the synthetic mechanisms involved in the use of TAA as a sulfur source in forming ZnS nanostructures from ZnO.

The inclusion of active materials in 3D-printed objects presents many potential applications in a variety of fields, including medicine and agriculture. Through a new three-phase coating system, we fabricate 3D objects that are printed via fused deposition modeling (FDM), with embedded functional materials. The method, namely Continuous Material Deposition on Filaments (CMDF) is based on passing a filament through a solution in which the functional substance is dissolved together with the polymer from which the filament is made. As model cases, three different types of materials were tested, Rhodamine B, ZnO nanoparticles (NPs), and Ciprofloxacin (Cip) while dissolved or dispersed in a PLA-containing solution. It was found that the properties of the coating materials are not affected by the coating and printing steps and they are maintained on the surface of the printed structure. This enabled, for example, achieving an antibacterial activity by the ZnO NPs and the controlled release of the antibiotics, Cip. Since the approach does not alter the mechanical properties of the printed structures, it offers a simple and convenient method for the introduction of a wide range of materials into 3D-printed objects.

Many stable water dispersions of various chemical compositions containing bioactive chemical compounds: copper silicate, titanium dioxide and zinc oxide (and other auxiliary substances) were developed and fabricated - they were used for preparation of thin hybrid coatings having very good antimicrobial properties against gram negative bacteria (Escherichia coli), gram positive bacteria (Staphylococcus aureus) and yeast fungus (Candida albicans). Polyester (PES) nonwovens were modified by dip-coating, and PES and cotton fabrics - by dip-coating and coating methods.