Svetlana R. Lukic-Petrovic

Heavy metal oxide glasses containing lead are typically stable against devitrification upon heating and they have a wide infrared transmittance, up to the wavel Heavy metal oxide glasses containing lead are typically stable against devitrification upon heating and they have a wide infrared transmittance, up to the wavel

"UV radiation can have a harmful effect on both humans and the environment. Therefore, developing UV shielding materials is an important step in protecting ourselves and the environment from the harmful effects of UV radiation. Here we present a detailed study of ZnO-SnO2/PMMA nanocomposite coatings, which completely block UVC radiation. Additionally, we study the effect of the addition of ZnO-SnO2 nanoparticles on mechanical properties in the means of Vickers microhardness and find out that they positively affect the microhardness of the PMMA coatings up to a certain concentration. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) reveal quite homogeneous distribution of nanoparticles for lower concentrations and the presence of nanoparticle aggregates for higher concentrations such as 1 wt.% and 5 wt.% of ZnO-SnO2 nanoparticles."

Currently, environmental pollution by various organic pollutants (e.g., organic dyes) is a serious, emerging global issue. The aqueous environment is highly exposed to the harmful effects of these organic compounds. Furthermore, the commonly applied conventional purification techniques are not sufficient enough. Heterogeneous photocatalysis and the photo-Fenton process are effective, low-cost and green alternatives for the removal of organic pollutants. In this study, different iron(III) oxide/titanium(IV) oxide/polyvinyl chloride (Fe₂O₃/TiO₂/PVC) nanocomposites in tablet form were investigated in the photodegradation of methylene blue (MB) under simulated sunlight, and their possible antibacterial effects were examined. The newly synthesized nanocomposites were characterized by scanning electron microscope, X-ray diffraction, UV–Vis diffuse reflectance spectroscopy, and Raman spectroscopy. The results showed a hematite crystal form in the case of Fe₂O₃₍₂₎ and Fe₂O₃ samples, while the Fe₂O₃₍₁₎ sample showed a combination of hematite and synthetic mineral akaganeite. The highest photocatalytic efficiency was achieved in the presence of Fe₂O₃/TiO₂/PVC, when 70.6% of MB was removed. In addition, the possible photo-cleaning and reuse of the mentioned photocatalyst was also examined. Based on the results, it can be seen that the activity did not decrease after five successive runs. Nanocomposites also exhibited mild antibacterial effects against the two tested Gram-positive bacteria (S. aureus and B. cereus).

A new titanium/molybdenum/mixed-oxides (TMO) contact-type heterojunction photocatalyst was prepared by a simple, low-cost, and environmentally-friendly mixing-calcination solid-state method. A microstructural investigation by scanning electron microscopy (SEM) showsirregularly shaped agglomerated morphology of TMO that consists of firmly connected globular TiO₂ and rod-like MoO₃ particles. The detailed structure and optical bandgap investigation by X-ray diffraction, Raman, and UV-Vis spectroscopy revealed the TMO’s composition of ~37 wt.% rutile TiO₂, ~25 wt.% of anatase TiO₂, and ~38 wt.% of molybdite MoO₃ phase and an absorption threshold of around 380 nm, which implies more probability of desirable higher visible light absorption. The removal efficiency of pesticides quinmerac (QUI) and tembotrione (TEM), and pharmaceuticals metoprolol (MET), amitriptyline (AMI), ciprofloxacin (CIP),and ceftriaxone (CEF) from water in the presence of starting pure TiO₂, MoO₃, and prepared TMO were investigated under different pH values and UV irradiation/simulated sunlight (SS). Each starting metal-oxide precursors and prepared TMO showed a different affinity for adsorption of tested pesticides and pharmaceuticals, and, in general, better photocatalytic degradation efficiency under UV irradiation than under simulated sunlight. The highest photocatalytic degradation efficiency under UV irradiation was 81.6% for TEM using TMO; using TiO₂ was 65.0% for AMI, and using MoO₃ was 79.3% for CEF after 135 min. However, TMO showed a very high synergic adsorption/photocatalytic under-SS efficiency in the removal of CIP of almost 80% and under UV irradiation of 90% CIP removal after 75 min. The toxicity of catalysts, starting compounds, and their intermediates formed during the removal process was assessed using a rat hepatoma cell line (H-4-II-E). The highest hepatotoxic effects were obtained by using UV irradiated QUI and MET suspension with TMO for up to 60 min.

This paper is concerned with establishing the correlation between some mechanical, thermal and structural properties of Pbx(As2S3)100-x glassy samples, x = 1, 2 and 3 at.%. Measurements of mechanical parameters were performed using a Fischerscope HM2000 S nanoindentation device. The obtained results indicated decrease in the microhardness as a function of the doping element content, as well as a pronounced normal indentation size effect (ISE) phenomenon in the range of lower indentation loads. In order to describe the microhardness data in the ISE regime and to determine the load independent microhardness value, the MPRS model was used. The increase in glass transition temperature with heating rate observed in DSC curves was described according to the Lasocka equation. The activation energy of softening process was evaluated using the Kissinger?s method. The KAS model was applied to estimate the activation energy as a function of the conversion rate. Raman measurements were employed to investigate structural changes due to Pb doping.

We report an investigation of the optical properties, structure and vibrational modes of SbxAs37-xS48I15 glasses (0 at.% < x < 37 at.%). Optical parameters such as the refractive index, the absorption coefficient, and the optical band gap are correlated to the glass composition. All parameters were found to follow an almost linear dependence with the antimony content x. Both the refractive index and the absorption edge wavelength exhibit systematic increase against x. Off-resonant Raman of the glasses spectra were measured and analyzed. Structural units, representative of the glass structure, were optimized by DFT calculations providing vibrational spectra in agreement with experiments. Raman spectra were interpreted based on the harmonic frequencies and the activities of vibrational modes obtained by the DFT analysis. The results showed evidence in favor of a statistical mixing of the Iodine atoms, among the various pyramidal units; hence discarding structural models suggesting the presence of isolated pyramidal molecules of the types AsI3 / SbI3. Both experimental data and DFT results suggested that Iodine atoms exhibit much higher propensity to replace sulfur atoms in antimony than in arsenic-based pyramids. In addition, comparison of experimental and simulated spectra of selected clusters in mixed glasses indicate that it is more probable to find corner-sharing Sb-based pyramids than As-based ones.