National Repository of Grey Literature 11 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Elements characterization in urban aerosol
Hlaváčková, Hana ; Cigánková, Hana ; Mikuška, Pavel ; Hegrová, J.
Elements are important components of atmospheric aerosols. Heavy metals are known environmental pollutants due to their toxicity and their ability to accumulate in the human body. Heavy metals can exhibit toxicological afects even in trace amounts.
Elements' bioaccessibility and oxidative potential of urban aerosol
Cigánková, Hana ; Mikuška, Pavel ; Hegrová, J.
Atmospheric aerosols (Particulate Matter, PM) have significant impact on health and environment. The ability of aerosol to produce reactive oxygen species (ROS) is one of the widely proposed mechanisms related to the negative effects of aerosol on human health. Oxidative stress, caused by the production of ROS, is associated with several cardiovascular and respiratory diseases.\nThe capacity of aerosol to produce ROS is also called oxidative potential (OP). Although ROS generation capacity of PM exhibits a good correlation with PM mass concentration, it may depend more on physico-chemical properties of PM. Elements bound to PM play a significant role in contributing to the OP of aerosol. Exposure to elements was linked with several health issues (e.g. respiratory and cardiovascular diseases, asthma, inflammatory effects, lung cancer).
Oxidative Potential of PM1 and PM2.5 Urban Aerosol and Associated Elements in Three Simulated Lung Fluids
Cigánková, Hana ; Mikuška, Pavel ; Hegrová, J.
Mass concentration of particulate matter (PM) has been used in several epidemiologic studies as an indicatior conenecting PM concentrations with human health effects (Ostro, 1993). However, mass concentration of PM doesn´t consider the different compositions and toxicological effects of its components. Majority of PM mass constitutes low-toxicity components, while minority of trace components may have high toxicological activity (Tonne, 2012). Oxidative potential (OP), defined as the ability of PM to induce oxidative stress, is in recent years recognized as one of the main biological mechanisms considered to be contributing to negative impacts from air pollution exposure. Oxidative stress is caused through the capability of PM to generate reactive oxygen species (ROS) within the lung, which leads to pro-inflammatory responses that can ultimately results in cell apoptosis (Borlaza, 2021).
Total and Bioaccessible Fraction of Elements in Urban Aerosol
Mikuška, Pavel ; Cigánková, Hana ; Hegrová, J.
Atmospheric aerosols have significant impact on health and environment. Elements constitute an important particulate component which have received the attention to understand their environmental and health impacts. Elements enter the human body through inhalation of aerosols causing several health issue (asthma, cardiovascular and respiratory diseases, lung cancer).\nThe potential health effects of elements in PM depend on their toxicity, concentration, and bioaccessibility. It is assumed that the bioaccessible fraction of elements is more relevant for evaluating human health risks than the total concentration of elements. The aim of this study was to determine the total and bioaccessible concentration of elements in urban PM1 and PM2.5 aerosol during four seasons.
Study of secondary phases in trip steel by advanced sem and afm techniques
Mikmeková, Šárka ; Ambrož, Ondřej ; Hegrová, J. ; Aoyama, T.
The paper aims to demonstrate a modern scanning electron microscope (SEM) as a powerful tool for visualization of the secondary phases in TRIP steel. The TRIP steel specimens prepared by various metallographic techniques were imaged by the SEM and the secondary phases presence was confirmed by an electron back-scattered diffraction (EBSD) technique. The chemical polishing by 5 % HF in H2O2 for 10 seconds results in selective etching for each individual phase, as confirmed by an atomic force microscopy (AFM) and hybrid AFM-in-SEM techniques. The phases are easily distinguishable in the SEM micrographs created by the low energy high take-off angle signal electrons. The proposed sample preparation technique together with special SEM imaging conditions enables us accurate analysis of distribution of secondary phases within the TRIP steel matrix and moreover, the retained austenite is distinguishable from the martensite phase.
Trip steel specimen preparation for advanced sem and EBSD
Ambrož, Ondřej ; Mikmeková, Šárka ; Hegrová, J. ; Aoyama, T.
Modern scanning electron microscopy (SEM) allows observations of specimens with high surface sensitivity. The surface sensitivity is significantly affected by the accelerating voltages. With the development of the scanning electron microscopy, the requirements for the surface quality of samples increase. Metallographic methods originally intended for light microscopy become insufficient. The problem occurs especially with multiphase materials having a fine-grained structure. The investigated TRIP steel consists of a ferritic-bainitic matrix, retained austenite and martensite phases. The sizes of the smallest phases are nanometer units. The volume of residual austenite was determined by X-ray diffraction. The basic preparation of all tested samples involved conventional metallographic grinding and very fine mechanical polishing. One sample was analysed in this state. Other samples were subsequently chemically polished, electropolished and chemical-mechanically polished. The specimens were observed in the SEM using a SE and a BSE detector at low energies immediately after the preparation. An EBSD was performed in the same areas to characterize the retained austenite. Topographical imaging by special AFM, integrated into the SEM, demonstrated that the mechanical polishing results in surface deformation and residual austenite is transformed. All other methods have their specifics and for modern sensitive SEM instruments it is necessary to optimize individual procedures.
Air quality monitoring in areas with high traffic load
Ličbinský, Roman ; Huzlík, Jiří ; Hegrová, Jitka
Emissions of pollutants are one of the most serious problems of transportation, particularly as a result of a significant risk to human health. The causes of emissions of pollutants to ambient air are the exhaust gases generated by the combustion of fuel in motor vehicles. They are complex mixtures containing hundreds of chemical substances at different concentrations contributing to long-term warming of the atmosphere, the so-called "greenhouse effect" or often with toxic, mutagenic and carcinogenic properties for humans. The presented methodology was developed within project TE01020168 - Center for effective and sustainable transport infrastructure (CESTI) with the financial support of the Technological Agency of the Czech Republic within the Competence Centres Programme. Its aim is to unify the procedures for the implementation and evaluation of air quality monitoring in order to provide objective information on the actual status and development of air quality in areas with intensive transport. It summarizes the legislatively defined requirements for air quality monitoring and at the same time defines the pollutants whose very important source is transport and which should be monitored when assessing the impact of transport on air quality: nitrogen dioxide, (nano)particles, benzene, or platinum group elements and benzo[a]pyrene. The methodology can be used by the Ministry of Transport, road owners or their managers (ŘSD, regions and municipalities) as an effective tool for controlling both long-term monitoring and indicative measurements of air quality in the vicinity of roadways. At the same time, it will find application to metering processors and organizations providing their own air quality measurement to provide a standardized procedure to ensure a precise air quality assessment based on real data. The methodology will also help to deepen the knowledge of the staff of all the mentioned institutions and provide a standardized procedure for which, for example, contracting authorities may refer to public procurement.
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Metals in atmospheric particulate matter
Barboříková, H. ; Mikuška, Pavel ; Hegrová, J. ; Pokorná, Petra ; Krajčovič, J.
Atmospheric pollution is one of the most serious global enviroment problem. Metals constitute important class of pollutants which have received athe attention of researchers all over the world. Metals have strong potential to be adsorbed on particulate matter and than enter the human body through inhalation causing several health issue (asthma, lung cancer).
Oxidative potetial of atmospheric aerosol as indicator of ROS formation
Barboříková, Hana ; Mikuška, Pavel ; Hegrová, J. ; Krajčovič, J.
Atmospheric particulate matter (PM) affects our environment especially human health because it contains many toxic chemical substances. The purpose of this study is to determine a total content and a soluble fraction of selected metals and also the contribution of metals soluble in pulmonary fluids to a total oxidative potential of PM.
A simple device for quantitation of Caspase 3 in individual apoptotic embryonic cells
Hegrová, Jitka ; Klepárník, Karel ; Přikryl, Jan ; Lišková, Marcela ; Matalová, Eva ; Foret, František
A newly developed system for the determination of Caspase 3 activity in individual apoptotic embryonic cells is described. Caspase 3, a cysteine-aspartic acid protease activated in the apoptotic pathway, plays an essential role in the programmed cell death. Moreover, failure of apoptosis is one of the main contributions to tumor development.

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