The Role of Cerium Valence in the Conversion Temperature of H2_2Ti3_3O7_7 Nanoribbons to TiO2_2-B and Anatase Nanoribbons, and Further to Rutile

CeO$_2$-TiO$_2$ is an important mixed oxide due to its catalytic properties, particularly in heterogeneous photocatalysis. This study presents a straightforward method to obtain 1D TiO$_2$ nanostructures decorated with CeO$_2$ nanoparticles at the surface. As the precursor, we used H$_2$Ti$_3$O$_7$ nanoribbons prepared from sodium titanate nanoribbons by ion exchange. Two cerium sources with an oxidation state of +3 and +4 were used to obtain mixed oxides. HAADF–STEM mapping of the Ce$^{4+}$-modified nanoribbons revealed a thin continuous layer at the surface of the H$_2$Ti$_3$O$_7$ nanoribbons, while Ce$^{3+}$ cerium ions intercalated partially between the titanate layers. The phase composition and morphology changes were monitored during calcination between 620 °C and 960 °C. Thermal treatment led to the formation of CeO$_2$ nanoparticles on the surface of the TiO$_2$ nanoribbons, whose size increased with the calcination temperature. The use of Ce$^{4+}$ raised the temperature required for converting H$_2$Ti$_3$O$_7$ to TiO$_2$-B by approximately 200 °C, and the temperature for the formation of anatase. For the Ce$^{3+}$ batch, the presence of cerium inhibited the conversion to rutile. Analysis of cerium oxidation states revealed the existence of both +4 and +3 in all calcined samples, regardless of the initial cerium oxidation state

Effects of physicochemical properties of TiO2 nanomaterials for pulmonary inflammation, acute phase response and alveolar proteinosis in intratracheally exposed mice

Nanomaterial (NM) characteristics may affect the pulmonary toxicity and inflammatory response, including specific surface area, size, shape, crystal phase or other surface characteristics. Grouping of TiO2 in hazard assessment might be challenging because of variation in physicochemical properties. We exposed C57BL/6 J mice to a single dose of four anatase TiO2 NMs with various sizes and shapes by intratracheal instillation and assessed the pulmonary toxicity 1, 3, 28, 90 or 180 days post-exposure. The quartz DQ12 was included as benchmark particle. Pulmonary responses were evaluated by histopathology, electron microscopy, bronchoalveolar lavage (BAL) fluid cell composition and acute phase response. Genotoxicity was evaluated by DNA strand break levels in BAL cells, lung and liver in the comet assay. Multiple regression analyses were applied to identify specific TiO2 NMs properties important for the pulmonary inflammation and acute phase response. The TiO2 NMs induced similar inflammatory responses when surface area was used as dose metrics, although inflammatory and acute phase response was greatest and more persistent for the TiO2 tube. Similar histopathological changes were observed for the TiO2 tube and DQ12 including pulmonary alveolar proteinosis indicating profound effects related to the tube shape. Comparison with previously published data on rutile TiO2 NMs indicated that rutile TiO2 NMs were more inflammogenic in terms of neutrophil influx than anatase TiO2 NMs when normalized to total deposited surface area. Overall, the results suggest that specific surface area, crystal phase and shape of TiO2 NMs are important predictors for the observed pulmonary effects of TiO2 NMs.Peer reviewe

Spodbudno učno okolje za nadarjene otroke v predšolskem in zgodnješolskem obdobju : zbornik povzetkov (Zbornik povzetkov ob strokovnem posvetu Spodbudno učno okolje za nadarjene otroke v predšolskem in zgodnješolskem obdobju)

Namen današnjega posveta je bolje razumeti značilnosti in učne potrebe nadarjenih otrok v vrtcu in prvih razredih osnovne šole, da bi jih lahko ustrezno spodbujali in spremljali v obdobju, ko so njihovi možgani najbolj dojemljivi za učenje, zato smo strokovno zelo počaščeni, da sta z nami dve psihologinji, ekspertki s tega področja: prof. dr. Ljubica Marjanovič Umek, doma in mednarodno uveljavljena razvojna psihologinja, ki že vrsto let raziskuje dejavnike razvoja v najzgodnejšem obdobju človekovega življenja, in specialistka za delo z nadarjenimi Jasna Cvetković Lay iz sosednje Hrvaške, ki razvojnopsihološka in pedagoška spoznanja odmevno aplicira v prakso z razvijanjem koncepta delavnic »Bistrić« za nadarjene otroke

Spodbudno učno okolje za nadarjene otroke v predšolskem in zgodnješolskem obdobju : zbornik povzetkov (Zbornik povzetkov ob strokovnem posvetu Spodbudno učno okolje za nadarjene otroke v predšolskem in zgodnješolskem obdobju)

Namen današnjega posveta je bolje razumeti značilnosti in učne potrebe nadarjenih otrok v vrtcu in prvih razredih osnovne šole, da bi jih lahko ustrezno spodbujali in spremljali v obdobju, ko so njihovi možgani najbolj dojemljivi za učenje, zato smo strokovno zelo počaščeni, da sta z nami dve psihologinji, ekspertki s tega področja: prof. dr. Ljubica Marjanovič Umek, doma in mednarodno uveljavljena razvojna psihologinja, ki že vrsto let raziskuje dejavnike razvoja v najzgodnejšem obdobju človekovega življenja, in specialistka za delo z nadarjenimi Jasna Cvetković Lay iz sosednje Hrvaške, ki razvojnopsihološka in pedagoška spoznanja odmevno aplicira v prakso z razvijanjem koncepta delavnic »Bistrić« za nadarjene otroke

Photocatalytic biocidal effect of copper doped TiO2 nanotube coated surfaces under laminar flow, illuminated with UVA light on Legionella pneumophila

Legionella pneumophila can cause a potentially fatal form of humane pneumonia (Legionnaires’ disease), which is most problematic in immunocompromised and in elderly people. Legionella species is present at low concentrations in soil, natural and artificial aquatic systems and is therefore constantly entering man-made water systems. The environment temperature for it’s ideal growth range is between 32 and 42°C, thus hot water pipes represent ideal environment for spread of Legionella. The bacteria are dormant below 20°C and do not survive above 60°C. The primary method used to control the risk from Legionella is therefore water temperature control. There are several other effective treatments to prevent growth of Legionella in water systems, however current disinfection methods can be applied only intermittently thus allowing Legionella to grow in between treatments. Here we present an alternative disinfection method based on antibacterial coatings with Cu-TiO2 nanotubes deposited on preformed surfaces. In the experiment the microbiocidal efficiency of submicron coatings on polystyrene to the bacterium of the genus Legionella pneumophila with a potential use in a water supply system was tested. The treatment thus constantly prevents growth of Legionella pneumophila in presence of water at room temperature. Here we show that 24-hour illumination with low power UVA light source (15 W/m2 UVA illumination) of copper doped TiO2 nanotube coated surfaces is effective in preventing growth of Legionella pneumophila. Microbiocidal effects of Cu-TiO2 nanotube coatings were dependent on the flow of the medium and the intensity of UV-A light. It was determined that tested submicron coatings have microbiocidal effects specially in a non-flow or low-flow conditions, as in higher flow rates, probably to a greater possibility of Legionella pneumophila sedimentation on the coated polystyrene surfaces, meanwhile no significant differences among bacteria reduction was noted regarding to non or low flow of medium

Structural properties and thermal stability of cobalt- and chromium-doped α-MnO2 nanorods

α-MnO2 nanorods were synthesized via the hydrothermal decomposition of KMnO4 in an acidic environment in the presence of Co2+ and Cr3+ ions. Reactions were carried out at three different temperatures: 90, 130 and 170 °C. All prepared samples exhibit a tetragonal MnO2 crystalline phase. SEM–EDS analysis shows that cobalt cations are incorporated to a higher degree into the MnO2 framework than chromium ions, and that the content of the dopant ions decreases with increasing reaction temperature. The oxidation of Co2+ to Co3+ during the reaction was proved by an XANES study, while EXAFS results confirm that both dopant ions substitute Mn4+ in the center of an octahedron. The K/Mn ratio in the doped samples synthesized at 170 °C is significantly lower than in the undoped samples. Analysis of an individual cobalt-doped α-MnO2 nanorod with HAADF-STEM reveals that the distribution of cobalt through the cross-section of the nanorod is uniform. The course of thermal decomposition of the doped nanorods is similar to that of the undoped ones. Dopant ions do not preserve the MnO2 phase at higher temperatures nor do they destabilize the cryptomelane structure

Gas Sensing with Iridium Oxide Nanoparticle Decorated Carbon Nanotubes

The properties of multi-wall carbon nanotubes decorated with iridium oxide nanoparticles (IrOx-MWCNTs) are studied to detect harmful gases such as nitrogen dioxide and ammonia. IrOx nanoparticles were synthetized using a two-step method, based on a hydrolysis and acid condensation growth mechanism. The metal oxide nanoparticles obtained were employed for decorating the sidewalls of carbon nanotubes. Iridium-oxide nanoparticle decorated carbon nanotube material showed higher and more stable responses towards NH3 and NO2 than bare carbon nanotubes under different experimental conditions, establishing the optimal operating temperatures and estimating the limits of detection and quantification. Furthermore, the nanomaterials employed were studied using different morphological and compositional characterization techniques and a gas sensing mechanism is proposed