Effect of CaO/ SiO2 ratio on viscosity and structure of slag

The objective of this work is experimental determination of temperature dependences of viscosity of the molten CaO - Al2O3 - SiO2 system and assessment of impact of CaO/SiO2 ratio on viscosity and structure of this system. Experimental measurements of viscosity were performed with use of the high-temperature viscometer Anton Paar FRS 1 600. Viscosity was measured in a rotational mode during heating at the rate of 3,3 °C/min in the temperature interval from 1 673 to 1 873 K. Viscosity in the molten oxide system is determined by the internal structure. Exact clarification of the change of structure of the oxide system caused by the increased content of CaO was performed by Fourier transform infrared spectroscopy.Web of Science54345845

Photocatalytic decomposition of nitrous oxide using TiO2 and Ag-TiO2 nanocomposite thin films

TiO2 and Ag-TiO2 (0.05, 0.25 and 1 wt% of Ag) thin films were prepared by the sol–gel method. The prepared films were characterized using SEM-EDAX, XRD, Raman spectroscopy, atomic force microscopy and UV–Vis spectrometry. Photocatalytic decomposition of N2O was performed in an annular batch reactor illuminated with an 8 W Hg lamp (254 nm wavelength). The photoreactivity of Ag-TiO2 increases with the Ag amount to 0.25 wt% Ag. Further increase of Ag loading to 1 wt% Ag did not change N2O conversion. The Ag particles deposited on the TiO2 surface can act as electron–hole separation centers. The presence of water vapor and oxygen in the reaction mixture slightly improved N2O conversion.Web of Science20917517

A low-cost photoactive composite quartz sand/TiO2

The photoactive quartz sand/TiO2 composites were prepared by thermal hydrolysis of the suspension obtained by addition of quartz sand to a titanyl sulfate solution. The required amount of TiO2 in the prepared composites (i.e. 9, 22 and 45 wt.%, respectively) was achieved using a variable titanyl sulfate/quartz ratio. As reference materials, pure TiO2 was prepared using the thermal hydrolysis of the titanyl sulfate solution under the same condition as used during the preparation of composite quartz/TiO2. The composite samples, dried at 105 °C and calcined at temperatures of 500–900 °C, were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. Structural ordering of TiO2 particles on the quartz surface was studied using atomistic simulations in a Material Studio modeling environment. Photodegradation activity of the composites was evaluated by the discoloration of Acid Orange 7 aqueous solution. The composite containing 22 wt.% of TiO2 and calcined at 800 °C exhibits the highest photoactivity. Higher and lower amounts of TiO2 led to worse results. The quartz/TiO2 composite is a promising material able to replace pure TiO2 in a wide range of building materials.Web of Science22249748

Identification of phase composition of binders from alkali-activated mixtures of granulated blast furnace slag and fly ash

The prepared alkali-activated binders (AAB) and composites using suitable latent hydraulic raw materials represent an alternative to materials based on Portland cements. This paper deals with ways how to influence the functional parameters of AAB by setting up mixtures of granulated blast furnace slag (GBFS) and fly ash with selected chemical compositions. In this way the course of hydration process is modified and the phase composition of products of alkali activation is changed as well as their final properties. The amorphous character of the hydration products makes evaluation of the phase composition of hardened AAB difficult and significantly limits the number of experimental techniques suitable to characterise their phase composition. It was observed that measuring the pH of water extracts obtained from the alkali-activated mixtures can give supplementary information about the process of hardening of alkali-activated mixtures of GBFS and fly ash.Web of Science581887

Solid anorganic particles and chronic rhinosinusitis: A histopathology study

Although extensive research has shown the pathological effect of fine and ultrafine airborne particles, clear evidence of association of environmental exposure to them and inflammatory changes in human nasal mucosa is missing. Meanwhile, pathogenesis of chronic rhinosinusitis, despite being a disease with high prevalence in the population, is still unclear. The increasing evidence of the pro-inflammatory properties of these particles raises the question of their possible role in chronic rhinosinusitis. The presented study focused on detection of microsized anorganic particles and clusters of nanosized anorganic particles in the nasal mucosa of patients with chronic rhinosinusitis by Raman microspectroscopy and comparison of their composition to histologic findings. The results were compared to the findings in mucosa obtained from cadavers with no history of chronic rhinosinusitis. Solid particles were found in 90% of tissue samples in the group with chronic rhinosinusitis, showing histologic signs of inflammation in 95%, while in the control group, the particles were found in 20% of samples, with normal histologic findings in all of them. The main detected compounds were graphite, TiO2, amorphous carbon, calcite, ankerite and iron compounds. The results are in accordance with the premise that exogenous airborne particles interact with the nasal mucosa and possibly deposit in it in cases where the epithelial barrier is compromised in chronic rhinosinusitis.Web of Science1912art. no. 726

Zpráva o výsledcích vědecko-výzkumné a vývojové činnosti na VŠB-TU Ostrava za rok 2018 : určeno pro zasedání Vědecké rady VŠB-TUO dne 1. 3. 2019

Ostrav

Identification of the phase composition of solid microparticles in the nasal mucosa of patients with chronic hypertrophic rhinitis using Raman microspectroscopy

Solid particles, predominantly in micron and submicron sizes, have repeatedly been observed as a threat to a human health unique compared to the other textures of the same materials. In this work, the hypothesis the solid metal-based particles play a role in the pathogenesis of chronic hypertrophic rhinitis was investigated in patients who had not responded positively to medication. In the group of 40 randomly selected patients indicated for surgical mucotomy, the presence of solid micro- and submicron particles present in their nasal mucosa was assessed. For comparison, a set of 13 reference samples from patients without diagnosed chronic hypertrophic rhinitis was evaluated. The analysis was performed using Raman microspectroscopy. The advantage of this method is the direct identification of compounds. The main detected compounds in the mucosa samples of patients with chronic hypertrophic rhinitis were TiO2, carbon-based compounds, CaCO3, Ca(Fe, Mg, Mn)(CO3)2 MgCO3, Fe2O3, BaSO4, FeCO3 and compounds of Al and Si, all of which may pose a health risk to a living organism. In the reference samples, only TiO2 and amorphous carbon were found. In the control group mucosa, a significantly lower presence of most of the assessed compounds was found despite the longer time they had to accumulate them due to their higher mean age. Identification and characterisation of such chemicals compounds in a living organism could contribute to the overall picture of the health of the individual and lead to a better understanding of the possible causes not only in the chronic hypertrophic rhinitis, but also in other mucosal and idiopathic diseases

Oxidative stress markers are elevated in exhaled breath condensate of workers exposed to nanoparticles during iron oxide pigment production

PubMed ID: 26828137Markers of oxidative stress and inflammation were analysed in the exhaled breath condensate (EBC) and urine samples of 14 workers (mean age 43  ±  7 years) exposed to iron oxide aerosol for an average of 10  ±  4 years and 14 controls (mean age 39  ±  4 years) by liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry (LC-ESI-MS/MS) after solid-phase extraction. Aerosol exposure in the workplace was measured by particle size spectrometers, a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS), and by aerosol concentration monitors, P-TRAK and DustTRAK DRX. Total aerosol concentrations in workplace locations varied greatly in both time and space. The median mass concentration was 0.083 mg m−3 (IQR 0.063–0.133 mg m−3) and the median particle concentration was 66 800 particles cm−3 (IQR 16 900–86 900 particles cm−3). In addition, more than 80% of particles were smaller than 100 nm in diameter. Markers of oxidative stress, malondialdehyde (MDA), 4-hydroxy-trans-hexenale (HHE), 4-hydroxy-trans-nonenale (HNE), 8-isoProstaglandin F2α (8-isoprostane) and aldehydes C6–C12, in addition to markers of nucleic acid oxidation, including 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU), and of proteins, such as o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr), and 3-nitrotyrosine (3-NOTyr) were analysed in EBC and urine by LC-ESI-MS/MS. Almost all markers of lipid, nucleic acid and protein oxidation were elevated in the EBC of workers comparing with control subjects. Elevated markers were MDA, HNE, HHE, C6–C10, 8-isoprostane, 8-OHdG, 8-OHG, 5-OHMeU, 3-ClTyr, 3-NOTyr, o-Tyr (all p  <  0.001), and C11 (p  <  0.05). Only aldehyde C12 and the pH of samples did not differ between groups. Markers in urine were not elevated. These findings suggest the adverse effects of nano iron oxide aerosol exposure and support the utility of oxidative stress biomarkers in EBC. The analysis of urine oxidative stress biomarkers does not support the presence of systemic oxidative stress in iron oxide pigment production workers.Web of Science101art. no. 01600

Analysis and modelling of single domain core-shell (αFeNi/chromite) nanoparticles emitted during selective laser melting, and their magnetic remanence

Despite recent intense implementation of increasingly eco-friendly additive manufacturing, the properties of nanoparticulate pollutants emitted during Laser Powder Bed Fusion are still not fully understood, and have generally been overlooked. This study aims to fill this gap in current research by providing new insights into distinct metal/oxide core-shell nanoparticles (3–36 nm) that are produced during 3D printing using stainless steel. It also suggests possible ways for the removal of these potentially harmful by-products. Further, this research also provides a newly developed kinetic model that predicts a metal core growth time of below 200 μs and confirms the predicted theory for the formation of these by-products. In the current study it was found that the cores produced during this process are purely metallic and consist of meteoroid phase kamacite (αFeNi). Within this study there was found to be a complete dominance of single-domain cores of kamacite with prevailing particles below the superparamagnetic threshold showing strong magnetic response and remanence. This new knowledge can be used to minimize potential health risks and reduce contamination of raw materials by this nanoparticulate pollutant, which can adversely affect the quality of printed metal parts, the environment, and the health of the operator. These findings also provide a new possibility of targeted efficient production of superparamagnetic core-shell nanoparticles with a metallic kamacite core during laser powder bed fusion of austenitic steel 316L powder, which can be used in the production of sensors.Web of Science400art. no. 13668

Biological response of an in vitro human 3D lung cell model exposed to brake wear debris varies based on brake pad formulation

Wear particles from automotive friction brake pads of various sizes, morphology, and chemical composition are significant contributors towards particulate matter. Knowledge concerning the potential adverse effects following inhalation exposure to brake wear debris is limited. Our aim was, therefore, to generate brake wear particles released from commercial low-metallic and non-asbestos organic automotive brake pads used in mid-size passenger cars by a full-scale brake dynamometer with an environmental chamber simulating urban driving and to deduce their potential hazard in vitro. The collected fractions were analysed using scanning electron microscopy via energy-dispersive X-ray spectroscopy (SEM-EDS) and Raman microspectroscopy. The biological impact of the samples was investigated using a human 3D multicellular model consisting of human epithelial cells (A549) and human primary immune cells (macrophages and dendritic cells) mimicking the human epithelial tissue barrier. The viability, morphology, oxidative stress, and (pro-)inflammatory response of the cells were assessed following 24 h exposure to similar to 12, similar to 24, and similar to 48 A mu g/cm(2) of non-airborne samples and to similar to 3.7 A mu g/cm(2) of different brake wear size fractions (2-4, 1-2, and 0.25-1 A mu m) applying a pseudo-air-liquid interface approach. Brake wear debris with low-metallic formula does not induce any adverse biological effects to the in vitro lung multicellular model. Brake wear particles from non-asbestos organic formulated pads, however, induced increased (pro-)inflammatory mediator release from the same in vitro system. The latter finding can be attributed to the different particle compositions, specifically the presence of anatase.Web of Science9272351233