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Fog and Cloud Processingof SMPS Spectra
Zíková, Naděžda ; Ždímal, Vladimír
Atmospheric aerosols have been studied extensively due to the confirmed influence of aerosols on global climate, aerosol – clouds interactions, atmospheric visibility, human health etc. (Kerminen et al., 2005; IPCC, 2007; Wichmann et al., 2000). However, the uncertainties connected to the effects of aerosols on phenomena in the atmosphere are considerable – there are various sources of aerosol particles, having different chemical compositions and particle size distributions (PSD). Moreover, the atmospheric aerosol is exposed to both dry and wet deposition, which further inflences the PSD. In this work, we have focused on cloud and fog processing of aerosol PSD.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22013101814583 - PDF
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Influence of Size Effect on Evaporation of Aerosol Nanoparticles
Levdansky, V.V. ; Smolík, Jiří ; Ždímal, Vladimír
Evaporation of nanoscale particles plays a significant role in many branches of nanotechnology and also in the atmospheric physics and chemistry. The classical approach to the description of evaporation of small (nanoscale) aerosol particles is usually based on the Kelvin equation. The mentioned equation was used in (Nanda et al., 2003) to interpret the results of experiments related to evaporation of free Ag nanoparticles. The authors of the above-mentioned paper assume that the surface tension of free Ag nanoparticles can be significant greater than the mentioned value for bulk matter. It is worth noting that this assumption is in contradiction with the Tolman theory (Tolman, 1949). Below we consider the influence of the size dependence of the cohesive energy in the nanoparticle on its evaporation.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22013101814594 - PDF
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Mass Size Distribution of Atmospheric Aerosols and Water Soluble Ions atMlada Boleslav in Winter
Schwarz, Jaroslav ; Zíková, Naděžda ; Vodička, Petr ; Hovorka, J. ; Moravec, Pavel ; Ždímal, Vladimír
The importance of the knowledge of aerosol mass size distribution for understanding aerosol behavior is well known for at least few decades. The water soluble ions represent a driving factor controlling hygroscopicity of aerosol particles that determines how the ambient relative humidity influences aerosol particle size. Therefore, hygroscopicity is a substantial parameter in phenomena like particle deposition in the human respiratory tract, particle – cloud interactions, aerosol optical effects etc. For these reasons, the mass size distribution of atmospheric aerosols and water soluble ions was studied at a Czech medium-size-town Mladá Boleslav in winter.
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Plný tet: SKMBT_C22013101815000 - PDF
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An Experimental Assesment of Changes to the Size Distribution of Ammonium Nitrate Under Isothermal Conditioning
Talbot, Nicholas ; Ondráček, Jakub ; Ždímal, Vladimír
Results show that for 50nm ammonium nitrate particles, 70-80% losses were recorded through the evaporation chamber. The least volatile was found to be 200nm particulate at 15°C. Generally, at 25°C the greatest reactions were found as was expected from prior research, however an overall increase in particulate concentration at 100nm for all temperature regimes was surprising. Possible multiple physiochemical transformations during transportation through the evaporator, along with activation of impurities within the water could explain these particle gains. The lack of humidity data, inter- transportation temperature profiling and lateral gas measurements limit the effectiveness of this study.
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Plný tet: SKMBT_C22013101814592 - PDF
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Characterization of Filter Materials for Aerosol Research – Size Resolved Penetration
Ondráček, Jakub ; Zíková, Naděžda ; Ždímal, Vladimír
The comparison of penetrations for different types of filtration materials showed wide variety of penetration curves, MPPS and the maximum penetration. This study also confirmed our initial doubts about the standard filter efficiency testing method, regarding the used testing material, setting of MPPS and measuring only the total penetration of polydisperse aerosol. Therefore, such a study could serve also as a basis for improvements in the filter efficiency standard method, which seems to give insufficient and in some perspectives limited or even misleading information.
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Plný tet: SKMBT_C22013091913090 - PDF
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Size Dependence of Incorporation of Gas Molecules into Aerosol Nanoparticles
Levdansky, V.V. ; Smolík, Jiří ; Ždímal, Vladimír ; Moravec, Pavel
The influence of size effects on the physicochemical transformations and transfer phenomena in the heterogeneous systems with nanoobjects attracts increasing attention of researchers. These problems are of interest for nanotechnology and atmospheric physics. Size effects can influence the cohesive energy as well as the activation energies of vacancy formation and diffusion of atoms in the nanoscale particles (Vanithakumari and Nanda, 2008). Phase transitions in aerosol systems with nanoscale particles (clusters) also depend on the nanoparticle size (Levdansky et al., 2010). Hear we discuss the size dependence of the mass accommodation coefficient in the aerosol system with nanoparticles.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22013091912290 - PDF
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