Příspěvky z konference

Příspěvky z konference Nalezeno 23,495 záznamů.  předchozí11 - 20dalšíkonec  přejít na záznam: Hledání trvalo 0.00 vteřin. 
Preparation and Relative Activity of Nobia-Supported CoMo Hydrodesulfurization Catalysts.
Kaluža, Luděk ; Zdražil, Miroslav
Evaluation of new supports alternative to alumina, for instance: ZrO2, TiO2, active carbon or zeolites, is an important topic of recent research on hydrodesulfurization catalysts. Nb2O5 was also considered as the support of Mo and Co(Ni)Mo sulfides and as a precursor of the active phase, niobium sulfide.
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Král v neklidné době: Přemysl Otakar II.
Žemlička, Josef
Studie je zaměřena na politickou a hospodářskou činnost Přemysla Otakara II., především zakládání měst.
Cloud Processing of Atmospheric Aerosol Spectra.
Zíková, Naděžda ; Pokorná, Petra ; Pešice, Petr ; Sedlák, Pavel ; Ždímal, Vladimír
Atmospheric aerosol (AA), and its influence on the cloud formation, lifetime and other properties, remains the most uncertain (with low confidence level) element in the IPCC radiative forcing estimations (Stocker et al., 2013). The AA, however, is influenced by the cloud processing as well (Collett et al., 2008., Zíková and Ždímal, 2016). Cloud processing of AA (and vice versa) can be described on fogs, or on low clouds present at a suitable station. An example of such a station is Milešovka, where fog is present for almost 55 % of the time (Fišák et al., 2009), giving a great opportunity to explore the changes in the particle size distributions due to the cloud processing.
The Distinctive Changes of Particles' Numeric Concentrations, Are Caused by Electrostatic Flue Gases Cleaning.
Molchanov, O. ; Krpec, K. ; Horák, J. ; Hopan, F. ; Ždímal, Vladimír ; Schwarz, Jaroslav
A burning processes are always accompanied by emissions, and solid fuel combustion is believed to be the main source of dust releases. Solid fuels are predominant for using by boilers under 300 kW, which are mostly use for heating the domestic buildings and small premises in industrial and other use. It is well known, that using such boilers is inevitably involves the pollution releases, among which are emissions of oxides of carbon, nitrogen and sulfur oxides and particulate matters. After 2020 all boilers in European Union are have to be consistent with the list of ecological norms, and norm ECODESIGN is the one of them. This norm, inter alia, means that PM concentration could not exceed 40 mg/m3N. Such legislative measures are compelling the producers to make steps to decrease boiler´s pollutions. However, it is hard to achieve the desired results by optimization of burning processes only. That´s why arises a need to equip the boilers with the gas cleaning units. Within this context, precipitation particulate matter with electrostatic method is one of the most perspective. Within studies to optimize the constructional and high voltages parameters of ESP, it was appeared unusual phenomenon, which has describing below.\n
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Characterization of Nitrogen Isotopic Composition in Fine Aerosol at a Central European Rural Background Station.
Vodička, Petr ; Kawamura, K. ; Schwarz, Jaroslav ; Kunwar, B. ; Ždímal, Vladimír
Studies of isotope ratios in atmospheric aerosols is relativelly new approach which can provide unique information on source emissions together with physical and chemical processes in the atmosphere (e.g. Kawamura et al., 2004). Here, we present seasonal variations in δ15N of total nitrogen (TN) in the PM1 fraction of atmospheric aerosols at a rural background site in Central Europe.\n
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Původ znečištění ovzduší na základě ročního měření PM2.5 a PM10 na dvou městských pozaďových stanicích v Praze.
Pokorná, Petra ; Schwarz, Jaroslav ; Rychlík, Š. ; Škáchová, H. ; Smolík, Jiří ; Ždímal, Vladimír ; Vlček, O. ; Hůnová, I.
Zlepšení kvality ovzduší ve městech je možné za předpokladu pochopení základních mechanismů především pokud se jedná o AA a jeho koncentrace, zdroje a původ (Viana et al., 2008). Cílem práce bylo určit původ znečištění ovzduší v Praze na základě ročního paralelního měření AA na dvou městských pozaďových stanicích.
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NMR Aerosolomics: A Convenient Route to Organic Aerosol Analysis.
Horník, Štěpán ; Schwarz, Jaroslav ; Sýkora, Jan
Atmospheric aerosols are a small but very important part of the Earth’s atmosphere. The proportion of inorganic and organic compounds in aerosol particles seems to be equal on average. While the inorganic composition of aerosols is well explored, knowledge about the organic part is still very limited. It is well known that the major part of organic aerosol compounds is represented by polar, water-soluble organic compounds (WSOC). So far GC-MS is the most frequently used method for WSOC analysis. GC-MS is a very sensitive technique; furthermore, it exploits huge spectra libraries accumulated over decades. Therefore, its role in the determination of aerosol composition is indisputable. Primarily owing to GC-MS, about 150 organic compounds have been identified in aerosol particles. NMR spectroscopy for the purpose of aerosol chemistry was discovered only recently as it is rather insensitive method. Nevertheless, NMR has undergone rapid development and sensitivity gain of late. Moreover, it is fully quantitative method and no sample derivatization is needed. So far, the use of NMR spectroscopy has been limited to so called Functional group analysis. In this analysis the whole NMR spectrum is divided into parts and subsequently integrated according to functional groups.
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Hydroscopic Behaviours of Ammonium Sulfate/Organic Mixtures Including Dicarboxylic Acid and Oligomer.
Bouzidi, Hichem ; Zuend, A. ; Ondráček, Jakub ; Schwarz, Jaroslav ; Ždímal, Vladimír
Here, the hygroscopic behavior of submicron particles composed of ammonium sulfate (AS), dicarboxylic acids (including oxalic acid (OA), malonic acid (MA)), and oligomer Poly(ethylene glycol) (PEG-300 (-CH2OCH2-)n) is investigated with a Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA), under relative humidity (RH) below 100%. The aerosol systems were varied in their complexity and ranged from single-component to more complex systems (2, 3 and 4 components). The experimental data are compared with predictions from Zdanovskii-Stokes-Robinson (ZSR) mixing rule (Stokes and Robinson, 1966) and the thermodynamic model Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) (Zuend et al., 2011).
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MOCVD Iron Oxide Nanoparticle Generation not Only for Follow-Up Inalation Exposure Experiments.
Moravec, Pavel ; Schwarz, Jaroslav ; Vodička, Petr ; Kupčík, Jaroslav ; Švehla, Jaroslav
Iron oxide nanoparticles (NPs) are industrially produced and commercially available and they are also frequently emitted into the environment by iron making plants. In the human body, iron is maintained at homeostatic fairly low level. However, freshly generated iron oxide NPs cause febrile and inflammatory response known as metal fume fever, but the potential in vivo consequences of inhalation of iron oxide NPs from the atmosphere has not yet been investigated. An overview of recent studies evaluating iron oxide NPs cytotoxicity, genotoxicity, developmental toxicity and neurotoxicity was presented by Valdiglesias et al. (2015). Toxicity of iron oxide NPs has been studied both in vitro and in vivo. Exposure chamber for the whole body inhalation experiments with small laboratory animals was constructed at the Institute of Analytical Chemistry of the CAS (Večeřa et al., 2011) and some methods of NPs generation for these experiments were already tested in our laboratory (Moravec et al., 2015; Moravec et al., 2016). In this study we tested a method of long lasting generation of iron oxide NPs by pyrolysis and oxidation of ironIII acetylacetonate (FeAA3).
Velikostní distribuce částic z inhalátorů - vliv nádechové rychlosti a vlhkosti.
Ondráčková, Lucie ; Ondráček, Jakub ; Kozáková, Jana ; Ždímal, Vladimír
Inhalační aerosoly produkované inhalátory typu MDI (metered dose inhaler) a DPI (dry powder inhaler) představují nedílnou součást léčby pacientů s plicními chorobami, jako je astma a chronická obstrukční plicní nemoc (CHOPN). Klíčovým parametrem určujícím místo a účinnost depozice v dýchacím ústrojí je velikostní distribuce částic aerosolu (Byron, 1990). Ta se může měnit v závislosti na složení léčiva a změně teploty a relativní vlhkosti při přechodu z inhalátoru do dýchacího ústrojí člověka. Pro analýzu velikostní distribuce částic z inhalátorů se doporučuje použití kaskádních impaktorů (European Farmacopeia, 2002). Tato metoda je však časově náročná a poskytuje malé rozlišení velikostního spektra. Alternativou je měření velikostní distribuce pomocí spektrometrů měřících dobu průletu částice aerosolu, které je i přes řadu omezení rychlejší a poskytuje vysoké rozlišení naměřených velikostních distribucí.
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