The effect of combination electrospun and meltblown filtration materials on their filtration efficiency

Filtration materials prepared by combination of electrospun nanofibers and meltblown microfibers (both fixed on polypropylene spunbond supports) were characterized from the point of view of their filtration efficiency in ultrafine particles separation. Compared are electrospun and meltblown structures and their combinations characterized by means of digital image analysis properly. Layer of electrospun nanofibers in MB air filtration materials can ensure improvement of filtration efficiencies for ultrafine particles separation

DNA methylation profiles in a group of workers occupationally exposed to nanoparticles

The risk of exposure to nanoparticles (NPs) has rapidly increased during the last decade due to the vast use of nanomaterials (NMs) in many areas of human life. Despite this fact, human biomonitoring studies focused on the effect of NP exposure on DNA alterations are still rare. Furthermore, there are virtually no epigenetic data available. In this study, we investigated global and gene-specific DNA methylation profiles in a group of 20 long-term (mean 14.5 years) exposed, nanocomposite, research workers and in 20 controls. Both groups were sampled twice/day (pre-shift and post-shift) in September 2018. We applied Infinium Methylation Assay, using the Infinium MethylationEPIC BeadChips with more than 850,000 CpG loci, for identification of the DNA methylation pattern in the studied groups. Aerosol exposure monitoring, including two nanosized fractions, was also performed as proof of acute NP exposure. The obtained array data showed significant differences in methylation between the exposed and control groups related to long-term exposure, specifically 341 CpG loci were hypomethylated and 364 hypermethylated. The most significant CpG differences were mainly detected in genes involved in lipid metabolism, the immune system, lung functions, signaling pathways, cancer development and xenobiotic detoxification. In contrast, short-term acute NP exposure was not accompanied by DNA methylation changes. In summary, long-term (years) exposure to NP is associated with DNA epigenetic alterations

Recommendations for reporting equivalent black carbon (eBC) mass concentrations based on long-term pan-European in-situ observations

A reliable determination of equivalent black carbon (eBC) mass concentrations derived from filter absorption photometers (FAPs) measurements depends on the appropriate quantification of the mass absorption cross-section (MAC) for converting the absorption coefficient (babs) to eBC. This study investigates the spatial–temporal variability of the MAC obtained from simultaneous elemental carbon (EC) and babs measurements performed at 22 sites. We compared different methodologies for retrieving eBC integrating different options for calculating MAC including: locally derived, median value calculated from 22 sites, and site-specific rolling MAC. The eBC concentrations that underwent correction using these methods were identified as LeBC (local MAC), MeBC (median MAC), and ReBC (Rolling MAC) respectively. Pronounced differences (up to more than 50 %) were observed between eBC as directly provided by FAPs (NeBC; Nominal instrumental MAC) and ReBC due to the differences observed between the experimental and nominal MAC values. The median MAC was 7.8 ± 3.4 m2 g-1 from 12 aethalometers at 880 nm, and 10.6 ± 4.7 m2 g-1 from 10 MAAPs at 637 nm. The experimental MAC showed significant site and seasonal dependencies, with heterogeneous patterns between summer and winter in different regions. In addition, long-term trend analysis revealed statistically significant (s.s.) decreasing trends in EC. Interestingly, we showed that the corresponding corrected eBC trends are not independent of the way eBC is calculated due to the variability of MAC. NeBC and EC decreasing trends were consistent at sites with no significant trend in experimental MAC. Conversely, where MAC showed s.s. trend, the NeBC and EC trends were not consistent while ReBC concentration followed the same pattern as EC. These results underscore the importance of accounting for MAC variations when deriving eBC measurements from FAPs and emphasize the necessity of incorporating EC observations to constrain the uncertainty associated with eBC.</p

Inter-annual trends of ultrafine particles in urban Europe

Ultrafine particles (UFP, those with diameters ≤ 100 nm), have been reported to potentially penetrate deeply into the respiratory system, translocate through the alveoli, and affect various organs, potentially correlating with increased mortality. The aim of this study is to assess long-term trends (5–11 years) in mostly urban UFP concentrations based on measurements of particle number size distributions (PNSD). Additionally, concentrations of other pollutants and meteorological variables were evaluated to support the interpretations. PNSD datasets from 12 urban background (UB), 5 traffic (TR), 3 suburban background (SUB) and 1 regional background (RB) sites in 15 European cities and 1 in the USA were evaluated. The non-parametric Theil-Sen's method was used to detect monotonic trends. Meta-analyses were carried out to assess the overall trends and those for different environments. The results showed significant decreases in NO, NO2, BC, CO, and particle concentrations in the Aitken (25–100 nm) and the Accumulation (100–800 nm) modes, suggesting a positive impact of the implementation of EURO 5/V and 6/VI vehicle standards on European air quality. The growing use of Diesel Particle Filters (DPFs) might also have clearly reduced exhaust emissions of BC, PM, and the Aitken and Accumulation mode particles. However, as reported by prior studies, there remains an issue of poor control of Nucleation mode particles (smaller than 25 nm), which are not fully reduced with current DPFs, without emission controls for semi-volatile organic compounds, and might have different origins than road traffic. Thus, contrasting trends for Nucleation mode particles were obtained across the cities studied. This mode also affected the UFP and total PNC trends because of the high proportion of Nucleation mode particles in both concentration ranges. It was also found that the urban temperature increasing trends might have also influenced those of PNC, Nucleation and Aitken modes.</p

Proceedings of the 12th International Conference on Kinanthropology

Proceedings of the 12th Conference of Sport and Quality of Life 2019 gatheres submissions of participants of the conference. Every submission is the result of positive evaluation by reviewers from the corresponding field. Conference is divided into sections – Analysis of human movement; Sport training, nutrition and regeneration; Sport and social sciences; Active ageing and sarcopenia; Strength and conditioning training; section for PhD students

Characterization of Filter Materials for Aerosol Research – Size Resolved Penetration

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

Viscosity behavior of Ge-Sb-S and Ge-Sb-Se supercooled liquids

Tato diplomová práce se zabývá přípravou a stanovením vybraných fyzikálních vlastností chalkogenidových skel (GeSe2)x(Sb2Se3)1-x a (GeS2)x(Sb2S3)1-x, kde x = 0,4 - 0,8. V teoretické části jsou popsány vlastnosti a využití těchto materiálů. Experimentální část je věnována měření hustoty při 25 °C, délkové teplotní roztažnosti v oblasti od 100 °C do teploty měknutí a viskozity v rozsahu 10 na4 - 10 na13 Pa.s připravených skel. Aplikovatelnost použitých metod měření je testována a diskutována. Teplotní závislost viskozity je extrapolována na základě vybraných modelů.This diploma work deals with synthesis and measurement of chosen physical properties of chalcogenide glass (GeSe2)x(Sb2Se3)1-x and (GeS2)x(Sb2S3)1-x, where x = 0.4 - 0.8. Theoretical part describes properties and application of these materials. Experimental part focused on measurements of density at 25 °C, thermal expansion coefficient in the range from 100 °C to softening point and viscosity in the range of 10 4 - 10 13 Pa.s prepared glasses. Applicability of used method is tested and discussed. The temperature dependence of viscosity is extrapolated on the base of chosen models.Fakulta chemicko-technologickáStudent přednesl prezentaci diplomové práce. doc. Hájek seznámil komisi s posudky. Proběhla diskuse k tématu diplomové práce: 1. Co znamená pojem "rozhodující rozměr tělesa"? 2. Co může způsobovat rozdíl přesnosti měření viskozity metodou penetrace válce nebo polokoulí? 3. Jakou hodnotu objemu jste použil při výpočtu viskozity pro neizotermní podmínky metody transverzálního toku? doc. Skopal: Je možné predikovat vlastnosti stavu krystalu měřených vlastností skelného přechodu? doc. Čičmanec: Jaký je rozdíl mezi metodami vyhodnocení naměřených výsledků? Vzhledem k vysokým hodnotám aktivační energie, může při skelném přechodu docházet i ke změně chemických vazeb?Dokončená práce s úspěšnou obhajobo