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Generation of TiO2 Nanoparticles for Follow-Up Inhalation Experiments with Laboratory Animals
Moravec, Pavel ; Schwarz, Jaroslav ; Vodička, Petr ; Koštejn, Martin
A method of TiO2 nanoparticle generation appropriate for follow-up long lasting inhalation experiments with laboratory animals was tested. Nanoparticles were synthesized in an externally heated tube reactor using titanium tetraisopropoxide as a precursor. Total 264 hours of particle generation in four experimental campaigns was performed with one batch of precursor without observable decrease of precursor volatility. Particle production was studied in wide range of experimental conditions such as reactor temperature, reactor flow rate and precursor vapor pressure by pyrolysis, using nitrogen as a carrier gas, and also in oxidizing atmosphere (10 vol. % of oxygen in the reaction mixture). Particle characteristics were investigated by scanning/transmission electron microscopy, energy dispersive spectroscopy, inductively coupled plasma optical emission spectrometry, elemental and organic carbon analyzer, X-ray diffraction and X-ray photoelectron spectrometry. As a result, particle production with number concentration high above 1.0 x 10(7) #/cm(3) and with primary particle size well below 50 nm can be easily achieved in most of investigated experimental conditions. Particles are free of elemental carbon, content of organic carbon is less than 10 weight %, detected crystalline phase is typically anatase, Ti is present in bonds Ti-O (TiO2) and total Ti concentration recalculated on TiO2 is approximately 80 mass %.
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Plný tet: SKMBT_C22015041615090 - PDF
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Influence of inhaled manganese oxides nanoparticles on mass of internal organs in mice
Zeman, T. ; Dočekal, Bohumil ; Mikuška, Pavel ; Buchtová, Marcela ; Míšek, Ivan ; Šerý, Omar ; Večeřa, Zbyněk
Results of the statistical analysis of a long-term inhalation experiment on laboratory mice are presented. During 17 weeks of the experiment, the experimental group was exposed to inhaled manganese oxides nanoparticles. Manganese oxides (MnO.Mn2O3) nanoparticles (MnONPs) were synthesized continuously via aerosol route in a hot wall tube flow reactor using a thermal decomposition of metal organic precursor manganese(II)acetylacetonate in the flow tube reactor (in vertical position) at temperature 750 °C in the presence of 30 vol% of oxygen. The concentration of produced MnONPs at the reactor output was in the range 1-3 × 107 particles/cm3 and the size of generated nanoparticles MnO.Mn2O3 was in the range 7-50 nm. Before entering the inhalation chamber, MnONPs in the mixture of N2, O2 and air (at total flow rate of 3 L/min) were further diluted using filtrated humidified air (20 L/min) at temperature 21 °C resulting in the MnONPs concentration 2 × 106 particles/cm3. At regular time intervals the mass of selected internal organs of mice from both experimental and control group was assessed. It has been proven that inhaled nanoparticles are able to influence the mass of internal organs of mice. Statistically significantly lower mass of kidneys, liver and spleen and higher mass of pancreas have been found in the experimental group compared to the control group.
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The first experiencies with new exposure system for the whole body inhalation experiments with small animals
Večeřa, Zbyněk ; Mikuška, Pavel ; Moravec, Pavel ; Smolík, Jiří
The first experiences with an inhalation chamber constructed for long-term exposure studies of small animals to nanoparticles under strictly controlled experimental conditions. The inhalation chamber was build from a glass and stainless steel and allows possible long-term inhalation procedures with up to four discrete groups of mice or of rats population under controlled illumination, temperature, relative humidity and pressure. Doses up to 1 x 10(6) particles/cm(3) and size (10-60 nm) of nano-sized particles were synthesized via aerosol route in a hot wall tube flow reactor using thermal decomposition of metal organic precursors. The function of exposure system for whole body inhalation experiments was studied under real conditions in period from May to September 2012. No animals were used within this trial experiment.
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A Comparison of Titania Nanoparticles Production in Two Different Reactors by MOCVD Method
Moravec, Pavel ; Smolík, Jiří ; Schwarz, Jaroslav ; Vodička, Petr ; Levdansky, V.V. ; Koštejn, Martin
Nanoparticles (NP's) have attracted considerable attention, because they show a quantum size effect, for which the physical and chemical properties are strongly dependent on particle size. This change of properties can also affect the toxicity and therefore NP's cannot be treated the same way as bulk material. In spite of that, inhalation studies of NP's are still rather rare. Recently, an exposure system for inhalation experiments was constructed in the Institute of Analytical Chemistry AS CR and the first experience with this system were reported by Večeřa et al., 2012. For these studies, a method of continual long-term generation of NP's in the gas phase is necessary. Methods for long-term generation of MnOx and Pb/PbOx NP's have recently been reported. The next task was to test the method for long-term generation of TiO2 NP's suitable for subsequent inhalation experiments.
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Plný tet: SKMBT_C22014102013554 - PDF
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Urban and Suburban Intermodal Fraction of Atmospheric Aerosol in Winter 2014
Kozáková, Jana ; Hovorka, J. ; Schwarz, Jaroslav
Fine (PM1) and coarse (PM10-2.5) aerosols differ not only in size but also in the chemical composition, health effects, type of sources, and others. A dividing line between fine and coarse aerosol is not clearly defined. These fractions overlap in the aerodynamic particle size range 1-2.5 μm, also called the intermodal fraction. Sources of both coarse and fine aerosols contribute to the intermodal fraction to a different extent relating to different meteorological conditions and types of locations. According to several studies, the intermodal fraction highly correlated with coarse aerosol in dry areas during high wind speed episodes. In contrast, other studies have shown higher or comparable correlation with fine aerosol. The aim of this study is to characterize the intermodal fraction in urban and suburban localities and estimate to what extent fine/coarse aerosol sources contribute to this fraction.
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Plný tet: SKMBT_C22014102013540 - PDF
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SMPS Spectra Dependence on Air Masses Origin at Košetice Station
Zíková, Naděžda ; Ždímal, Vladimír
The varibility in atmospheric aerosol (AA) concentrations is considerable even at rural background stations with suppressed direct anthropogenic influence (Zíková & Ždímal, 2013), and strongly depends, among other meteorological parameters, on wind speed and direction. The wind direction, however, gives only limited information on the air masses origin, so the more detailed analysis of air mass trajectories was done to describe the variability of the AA at the Košetice station.
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Plný tet: SKMBT_C22014102013541 - PDF
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