Papers by Jaroslav Schwarz
Zenodo (CERN European Organization for Nuclear Research), May 31, 2023
Fluid Phase Equilibria, Jun 1, 2020
This paper is a continuation of a study focused on thermodynamic properties of isomeric and quasi... more This paper is a continuation of a study focused on thermodynamic properties of isomeric and quasiisomeric ionic liquids. In this work 5 novel ionic liquids were synthesized, namely 1-(2-(2-ethoxyethoxy) ethyl)-3-alkylimidazolium bis(trifluoromethylsulfonyl)imides, where alkyl stands for different C 5 substituents. These species were characterized as to their isobaric molar heat capacity and thermal stability. The results are discussed with respect to different substituent isomerism and compared with data from our previous work (Rotrekl, Fluid Phase Equilib. 2017) that reported on a similar group of isomeric ionic liquids, namely 1-butyl-3-alkylimidazolium bis(trifluoromethylsulfonyl)imides. Data analysis of the experimental heat capacites was carried out using a non-statistical approach of the mathematical gnostics. The conclusions drawn from the present work bring an insight into the fine structure-property relationship which is useful in the development of predictive tools as well as it direct applications such as in energy storage or thermal fluids development.
Aerosol and Air Quality Research, 2021
Seasonal variation and sources of elements bound to urban aerosol were studied. Fine (PM2.5) and ... more Seasonal variation and sources of elements bound to urban aerosol were studied. Fine (PM2.5) and submicron (PM1) aerosol was collected at 2-week campaigns during four seasons in 2018. The total concentration of 21 elements accounted on average for 3.5% of the total PM2.5 mass concentration and 2.0% of the total PM1 mass concentration. Seasonal differences in the element concentrations in PM1 and PM2.5 were found. Most elements in both aerosol size fractions had a higher concentration in winter or autumn than in summer or spring. Enrichment factor analysis showed extremely highly enriched Cd, Sb and Se in both fractions. Positive matrix factorization (PMF) analysis revealed 3 sources (residential heating, resuspension and anthropogenic background) for PM1 and 3 sources (residential heating, resuspension and brake abrasion) for PM2.5 aerosol in Brno. In addition, health risk assessment of possibly toxic elements was calculated.
Journal of Aerosol Science, Sep 1, 1995
Journal of Aerosol Science, May 1, 1994
Aerosol Science and Technology, Sep 12, 2016
A method of long-lasting TiO 2 nanoparticle generation was tested for use in follow-up studies of... more A method of long-lasting TiO 2 nanoparticle generation was tested for use in follow-up studies of the health impacts of nanoparticles on laboratory animals during several weeks' long exposure experiments. Nanoparticles were synthesized in an externally heated tube reactor by pyrolysis and oxidation of titanium tetraisopropoxide. Particle production was studied under varying reactor temperature, reactor flow rate, and precursor vapor pressure. A total of 264 h of particle generation were performed in four experimental campaigns using one batch of precursor without an observable decrease of particle production. As a result, particle production with number concentrations high above 1.0 £ 10 7 #/cm 3 and with primary particle sizes well below 50 nm could be achieved in most of the investigated experimental conditions. Maximum of particle mass concentration reached the value 9500 mg/m 3 , which corresponds with emission rate 29 mg/min. The dependence of nanoparticle production and characteristics on experimental conditions was evaluated and the most suitable parameters for exposure experiments were specified. A comparison of the results with data from the literature shows that the material of the reactor plays a significant role in the process of particle formation.
Advances in Science and Research, May 6, 2015
Long-lasting research infrastructures covering the research areas of atmospheric chemistry, meteo... more Long-lasting research infrastructures covering the research areas of atmospheric chemistry, meteorology and climatology are of highest importance. The Atmospheric Station (AS) Křešín u Pacova, central Czech Republic, is focused on monitoring of the occurence and long-range transport of greenhouse gases, atmospheric aerosols, selected gaseous atmospheric pollutants and basic meteorological characteristics. The AS and its 250 m tall tower was built according to the recommendations of the Integrated Carbon Observation System (ICOS) and cooperates with numerous national and international projects and monitoring programmes. First measurements conducted at ground started in 2012, vertical profile measurements were added in 2013. A seasonal variability with slightly higher autumn and winter concentrations of elemental and organic carbon was revealed. The suitability of the doubly left-censored Weibull distribution for modelling and interpretation of elemental carbon concentrations, which are often lower than instrumental quantification limits, was verified. Initial data analysis also suggests that in summer, the tower top at 250 m is frequently above the nocturnal surface inversions, thus being decoupled from local influences.
Aerosol Science and Technology, Dec 20, 2018
A method of continual ZnO nanoparticle generation was tested for use in follow-up longterm inhala... more A method of continual ZnO nanoparticle generation was tested for use in follow-up longterm inhalation exposure experiments with small laboratory animals. Nanoparticles were synthesized in an externally heated tube reactor by the evaporation of metallic zinc into a stream of nitrogen carrier gas, followed by the oxidation of zinc vapor in a stream of air and the formation of nanoparticles by a chemical vapor condensation method. The nanoparticle production was studied at various evaporation temperatures, reactor flow rates and flow rates of mixing air. Particle generation for more than 100 h in two experimental runs with one batch of the zinc precursor was performed without a considerable decrease in the particle production rate. As a result, particle production with a number concentration much greater than 1.0 10 7 #/cm 3 , a mean particle/agglomerate size well below 50 nm and an emission rate greater than 5 μg/min was obtained under most of the investigated experimental conditions. A maximum emission rate of 16.3 μg/min was obtained at an evaporation temperature of 530 °C, a reactor flow rate of 800 cm 3 /min and a mixing flow rate of 2000 cm 3 /min and could be further increased by an increase in the evaporation temperature. The particle characteristics were studied, and estimates of the lung surface deposition area were calculated on the basis of the model developed by the International Commission of Radiological Protection.
Journal of Molecular Liquids, Sep 1, 2017
Influence of the alkyl side chain length on the thermophysical properties of chiral ionic liquids... more Influence of the alkyl side chain length on the thermophysical properties of chiral ionic liquids with a (1R,2S,5R)-(-)-menthol substituent and data analysis by means of mathematical gnostics
Aerosol Science and Technology, Jan 29, 2016
This study describes a method to calculate equivalent black carbon (EBC) concentrations comparabl... more This study describes a method to calculate equivalent black carbon (EBC) concentrations comparable to those obtained from optical filter-based EBC instrumentation from data obtained with a semi-continuous thermo-optical analyzer (Sunset Laboratory Inc., USA) without any need of instrument alterations or extra costs. A correction for the reflection of the Sunset analyzer laser beam by the walls of the sampling tube is introduced. EBC Sunset concentrations obtained during two intensive campaigns in Prague (one in winter and one in summer) were compared also to EBC measured by an AE31 Aethalometer (EBC aeth ), an AE51 MicroAethalometer (EBC micro ), and a Multi Angle Absorption Photometer (EBC MAAP ). Good agreement was observed in both campaigns. The EBC Sunset data were also corrected for loading effects in two ways-a simple loading correction and a total correction using data also from the MAAP and a nephelometer. The loading corrections gave similar results for EBC Sunset and the aethalometer data except for the simple correction for summer EBC Sunset data. The multiple scattering correction factors computed for EBC Sunset agreed well with those calculated for EBC aeth . The wall reflection correction for the Sunset analyzer data further improves the agreement between EBC Sunset and EBC MAAP .
Sugar like substances are usually small but important part of organic aerosol being often tracers... more Sugar like substances are usually small but important part of organic aerosol being often tracers for individual aerosol sources. Twelve hours samples (day and night) collected during winter and summer campaigns at three Central European rural background sites were utilized to characterize PM2.5 aerosol using complex set of analytical methods. Here we report concentrations of sugars, sugar like alcohols and sugar anhydrides.PM2.5 samplings were performed during February–March and July–August 2021 at three sites, National Atmospheric Observatory Košetice – CZ (NAOK, N 49°35′, E 15°05′; 534 m a.s.l.), Frýdlant – CZ (N 50°94′, E 15°07′; 366 m a.s.l.) and Melpitz –DE (N 51°32', E 12°56'; 86 m a.s.l.). Each site was equipped with high volume Digitel sampler using sampling flow rate 500 l/min. Cut parts of the filter were extracted with ultrapure water and the extracts were analysed using HPAE-PAD analysis and Thermo Scientific 5000+ system for sugar-like substances using a method...
The source apportionment of organic aerosols (OA) in background locations is one of the important... more The source apportionment of organic aerosols (OA) in background locations is one of the important issues in contemporary air quality protection. A better understanding of the atmospheric aerosols origin and their source apportionment in different locations is essential for improving air quality.Measurements of non-refractory PM1 (NR-PM1) were simultaneously performed during winter (1st February – 10th March) and summer (1st July – 20th August) 2021 at three background sites, National Atmospheric Observatory Košetice (N 49°35′, E 15°05′; 534 m a.s.l.) and Frýdlant (N 50°94′, E 15°07′; 366 m a.s.l.) in Czech Republic, and Melpitz (N 51°32', E 12°56'; 86 m a.s.l.) in Germany. Each site was equipped with an Aerosol Mass Spectrometer: a ToF- Aerosol Chemical Speciation Monitor (ToF-ACSM) at Košetice, a Compact Time-of-Flight Aerosol Mass Spectrometer C-ToF-AMS) at Frýdlant, and a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) at Melpitz.A Positive Matrix F...
Chemicke Listy, 2017
Carbonaceous aerosols in atmosphere are often analyzed in the form of two basic components – orga... more Carbonaceous aerosols in atmosphere are often analyzed in the form of two basic components – organic carbon (OC), which represents a wide range of organic compounds, and elemental carbon (EC). This paper describes in detail the principles of thermo-optical analysis of EC and OC in aerosols. Further it shows the possibilities of the data interpretation, as well as examples from real measurements.
Environmental Pollution, 2020
Characterizing Black Carbon (BC) at regional background areas is important for better understandi... more Characterizing Black Carbon (BC) at regional background areas is important for better understanding its impact on climate forcing and health effects. The variability and sources of Equivalent Black Carbon (EBC) in PM 10 (atmospheric particles with aerodynamic diameter smaller than 10 mm) have been investigated during a 5-year measurement period at the National Atmospheric Observatory Ko setice (NAOK), Czech Republic. Ground based measurements were performed from September 2012 to December 2017 with a 7-wavelength aethalometer (AE31, Magee Scientific). The contributions of fossil fuel (EBC ff ) and biomass burning (EBC bb ) were estimated using the aethalometer model. Seasonal, diurnal and weekly variations of EBC were observed that can be related to the sources fluctuations and transport characteristic of pollutants predominantly associated with regional air masses recirculating over the Czech Republic and neighboring countries. The absorption Ångstr€ om exponent (a-value) estimated in summer (1.1 ± 0.2) was consistent with reported value for traffic, while the mean highest value (1.5 ± 0.2) was observed in winter due to increased EBC bb accounting for about 50% of the total EBC. This result is in agreement with the strong correlation between EBC bb and biomass burning tracers (levoglucosan and mannosan) in winter. During this season, the concentrations of EBC bb and Delta-C (proxy for biomass burning) reached a maximum in the evening when increasing emissions of wood burning in domestic heating devices (woodstoves/heating system) is expected, especially during the weekend. The diurnal profile of EBC ff displays a typical morning peak during the morning traffic rush hour and shows a decreasing concentration during weekends due to lower the traffic emission.
Atmospheric Environment: X, 2021
Similarities and differences in the submicron atmospheric aerosol chemical composition are analyz... more Similarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62 • N and 10 • W -26 • E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and
Nanomaterials, 2018
There is a growing body of literature examining potential hazards of engineered nanomaterials. Th... more There is a growing body of literature examining potential hazards of engineered nanomaterials. This session will take stock of some of that literature and in particular, consider High Aspect Ratio Nanomaterials (HARNs) and more specifically carbon nanotubes. The first part of the session will address the oxidative/stress effects of various metallic nanoparticles. This will be followed by a discussion of a Horizon 2020 project known as BIORIMA. BIORIMA is a multinational collaboration to assess hazards of nano biomaterials and develop appropriate risk management tools. The remaining presentations will focus on a range of issues related to HARNs. These include assessing the similarities between carbon nanotubes (CNT) and asbestos, the identification of molecular initiating events of CNT in biological systems, the role of fibre rigidity in toxicity, mechanisms of CNT-induced inflammation, dustiness as a risk group strategy, the state of knowledge on occupational exposures, and risk management. Clearly there are many types of CNT in commerce and it is difficult to characterise the hazard with a single description. These sessions will help to identify the many factors that need to be considered.
Atmospheric Environment, 2018
Elemental carbon (EC) and organic carbon (OC) in fine atmospheric aerosols (PM 2.5 : aerodynamic ... more Elemental carbon (EC) and organic carbon (OC) in fine atmospheric aerosols (PM 2.5 : aerodynamic diameter smaller than 2.5 µm) have been measured with a semi-automatic instrument during a 4-year survey at the National Atmospheric Observatory Košetice (NAOK), Czech Republic. Ground based measurements were performed from March 2013 to December 2016 with a field Semi-Continuous OCEC Aerosol Analyzer (Sunset Laboratory Inc., USA). The variation of EC and OC concentrations and the OC/EC ratio was characterized for different seasons and days of the week. During our survey, higher concentrations of EC and OC were observed in winter (0.83 ± 0.67 and 3.33 ± 2.28 µg m -3 , respectively), and lower concentrations were recorded in summer (0.34 ± 0.18 and 2.30 ± 1.15 µg m -3 , respectively). Inversely, the OC/EC ratio with mean value (5.1 ± 2.6) characteristic to rural background area was higher in summer (7.33 ± 3.23) in comparison to the other seasons. Since the data contain values below detection and quantification limits of the measuring device (i.e., censored values), statistical methods for censored data have been used in order to compare mean EC and OC concentrations between various seasons. It was found out that there is a significant difference between summer and the other seasons with the exception of mean OC concentrations at noon. In most cases, there was also a significant difference between winter and the other seasons. Moreover, it was found out that when dealing with OC concentrations, it is possible to replace censored values by a constant and still obtain reasonable results. In case of EC concentrations, the method based on censored distributions should be preferred when the sample size is small and the proportion of censored values is high. The diurnal variation of EC and OC is less pronounced in summer. During working days, the EC diurnal pattern displays a morning (between 6:00 and 10:00) and an afternoon/evening (between 18:00 and 22:00) peaks, while for OC, only the afternoon/evening peak is observed. These seasonal, diurnal and weekly variations of EC and OC concentrations and OC/EC ratio are probably related to variability in terms of emission sources (residential heating, traffic), transport characteristic and meteorological conditions. A weaker correlation between EC and OC in summer (r = 0.56) suggests additional sources and/or transport processes during other seasons. The elevated OC/EC ratio, the higher correlation between OC and O 3 , and the temperature and solar radiation during summer confirmed an increasing contribution of OC from secondary organic carbon (SOC) estimated as at least 59 ± 11% of total carbon in the PM 2.5 using the EC tracer method. Backward trajectories of air masses arriving at 100 m AGL calculated in winter and summer show that higher pollution episodes of EC and OC are predominantly associated with continental air masses confined over Central Europe (about 79%), while lower EC and OC levels are mainly associated with episodes of long-range transport of marine air masses. Interestingly, the results reveal that in winter pollutants emitted during workdays could be accumulated above the region and influence the rural background air quality during some prolonged time of the weekend, especially on Saturday.
Atmospheric Environment, 2016
Artefacts bias the sampling of carbonaceous matter by quartz fibre filters. Identical thermal pro... more Artefacts bias the sampling of carbonaceous matter by quartz fibre filters. Identical thermal protocols run on various instruments produce different results. Seasonal variations can be observed in intensive carbonaceous aerosol variables. TC/PM 10 ratios range from 12 to 34% across European regional background sites. Site-mean EC/TC ratios range from 10 to 22% and get similar at all sites in winter.
Water-soluble dicarboxylic acids (hereafter diacids) and sugars are an important part of the atmo... more Water-soluble dicarboxylic acids (hereafter diacids) and sugars are an important part of the atmospheric water-soluble organic aerosol. Here, we studied diacids and other compounds in fine aerosol particles (PM1) collected at a rural background site National Atmospheric Observatory Košetice (NAOK), Czech Republic, Central Europe. Aerosol samples were collected every second day for 24 h from September 2013 to August 2014 (n=146). Based on receptor modeling (PMF), we identified PM1 organic compounds that are more typical to anthropogenic and to biogenic sources. We have apportioned two anthropogenic sources especially evident during the heating season from mid-October to mid-April: (i) biomass burning (BB) (main contribution of levoglucosan and methylsuccinic, maleic, methylmaleic and azelaic acids) and (ii) fossil fuel combustion (FF) (represented by phthalic, terephthalic and ketomalonic acids). Furthermore, we identified two sources of biogenic aerosols: (iii) summer factor was lar...
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Papers by Jaroslav Schwarz