We investigated a hypothesis that stabilizing silver within bioactive hydroxyapatite composite is capable to provide safe and effective antibacterial action. The nanocomposite made of bioactive, mineral hydroxyapatite (HAp) and antibacterial silver (Ag) is studied for interactions with both, bacterial and human cells. The nanocomposite provides controlled release of Ag ions; induces severe damages in bacterial cells and is capable for strong bacteriostatic and bactericidal action. However, the mechanism is non-selective and has the same effect to human osteosarcoma and fetal lung fibroblasts cells that confirmed strong toxicity. The results led to the conclusion that the material based on silver cannot be stabilized, and they must be replaced with a more selective and less toxic technology.
COBISS.SI-ID: 29292327
The formation of a ½ monolayer (ML) of strontium (Sr) on Si(001) represents the most widely used and effective passivation procedure for the epitaxial growth of strontium titanate (SrTiO3) on Si with molecular beam epitaxy (MBE). In the present study we demonstrate experimentally the possibility of preparing such a buffer layer with the pulsed-laser deposition (PLD) technique. In-situ analysis using reflection high-energy electron diffraction (RHEED) showed surface structure evolution from two-domain (2×1)+(1×2), exhibited by the bare silicon surface, to a (3×2)+(2×3) structure at 1/6 ML Sr coverage, which is then replaced by (1×2)+(2×1) structure at ¼ ML and maintained up to ½ ML coverage. In addition, two different processes for the removal of native SiO2 layer were studied: thermal and Sr-induced deoxidation process. Annealing above 1100°C proved to be the most efficient in terms of carbon contamination. The results highlight the possibilities of using the PLD technique for the synthesis of an epitaxial SrTiO3 layer on Si, needed for the integration of different functional oxides with a Si platform.
COBISS.SI-ID: 28399143
We prepared micrometer-sized structures consisting of TiO2 nanoparticles using the sol–gel technique in combination with the structure-directing agent triethanolamine (TEA). The TEA led to the formation of TEA- titanate complexes, which enabled the assembly of the sol-gel structures. Upon thermal crystallization these structures turn into micrometer-sized structures consisting anatase and rutile nanoparticles. The materials prepared with the structure-directing agent enable: (i) efficient degradation of the azo dye under both UV and Vis irradiation, as well as (ii) consolidation of the nanoparticles into micrometer-sized structures that represents a reduced environmental hazard.
COBISS.SI-ID: 28722983
Lead-free piezoelectrics are materials exhibiting great potential, particularly because of their extended strains under high fields. However, the reported electrical properties remain inconsistent due to difficulties related to sample preparation. The synthesis of K0.5Bi0.5TiO3 is characterized by the formation of K- and Bi-rich secondary phases and a reaction with humidity, which has a strong impact on the electrical properties. These are very much improved after prolonged sintering, ascribed to the elimination of the hygroscopic K2O-rich phase. The electrical properties are improved in terms of a decrease in the dielectric losses, a two-fold increase in the permittivity value at the maximum, an increase in the remanent polarization to 29 C/cm2, and an increase in the small signal d33 value from 40 to 120 pC/N.
COBISS.SI-ID: 28539687
Structurally and morphologically different colloidal manganese oxide solids, including manganosite (MnO), bixbyite (Mn2O3) and hausmannite (Mn2+[Mn3+]2O4), were obtained through the initial biomimetically induced precipitation of a uniform, nanostructured and micron-sized rhodochrosite(MnCO3) precursor phase and their subsequent thermally controlled transformation into oxide structuresin air and Ar/H2 atmospheres. The results showed that the structurally diverse, micron-sized, spherical manganese oxide particles exhibit unusual and fascinating nanostructured surface morphologies. These were developed through the coalescence of an initially formed, nanosized, crystalline, manganese carbonate precursor phase which, during the heating, transformed into coarser, irregular, elongated, micron-sized, manganese oxide solids. The prepared samples were characterized according to their structure, particle size, SSA and electrocinetic properties.
COBISS.SI-ID: 29284647