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Characterization of Aerosol Generated by Laser Ablation for Inductively Coupled Plasma Mass Spectroscopy.
Holá, M. ; Ondráček, Jakub ; Nováková, H. ; Vojtíšek, M. ; Šperka, J. ; Havlíček, M. ; Kanický, V.
Laser ablation (LA), together with inductively coupled plasma mass spectrometry (ICP-MS) as a detection system, has become a routine method for the direct analysis of various solid samples. The product of laser ablation contains a mixture of vapour, droplets and solid particles. All components are finally transported to a plasma by a carrier gas in form of dry aerosol that includes mainly agglomerates of primary nanoparticles. Dry aerosol can be studied by different offline or online techniques. In general, characterisation of aerosols by their particle size distribution (PSD) represents indispensable tool for fundamental studies of the interaction of laser radiation with various materials. Many works have studied PSD of dry aerosol for different samples, and different ablation conditions (Hola et al., 2010).The laser ablation was performed with nanosecond laser (193 nm) on glass and steel samples using various ablation conditions (spot size, ablation mode, repetition rate, fluence). The aerosol characterization was made first by online PSD monitoring using Engine Exhaust Particle Sizer (EEPS) simultaneously with laser ablation - ICP-MS analysis. Second, the structure of the laser-generated particles was studied off-line using scanning electron microscopy (SEM) and atomic force microscopy (AFM).
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22017103113070 - PDF
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A detailed study on aerosol particle size distribution in indoor and outdoor environments with attention to ammonium nitrate transormations
Talbot, Nicholas Philip ; Ždímal, Vladimír (advisor) ; Hovorka, Jan (referee) ; Vojtíšek, Michal (referee)
Due to its prevalence over large, densely populated areas, ammonium nitrate is an important chemical species in aerosol research. However, due to its volatility at ambient temperatures and over low temperature gradients, ammonium nitrate can be a difficult species to accurately measure. The volatility of ammonium nitrate is known to be dependent on temperature, relative humidity, the internal mixing state of the particle, and availability of the precursor gas constituents. The particle's physical state affects the equilibrium constant value of the ammonium nitrate - nitric acid / ammonia exchange and helps determine the dissociation rate. For indoor aerosol research, the outdoor originating aerosol particles' exposure to the new physical conditions indoors, such as changes in temperature, humidity, and particle-surface reactions within the microenvironment all accelerate ammonium nitrate dissociation. This increased rate of partitioning can generate artifacts on datasets, increase indoor particle formation, and accelerate the corrosion of cultural antiquities through acidification. The magnitude of these impacts is uncertain due to the current lack of knowledge on particle transformation processes when outdoor originating particles migrate indoors. To address this gap in knowledge, this thesis...
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The entry of lead into the brain after experimental administration of lead acetate
Patková, Jana ; Žurmanová, Jitka (referee) ; Vojtíšek, Maxmilián (advisor)
Lead is a ubiquitous environmental toxin that induces a broad range of fysiological, biochemical and behavioral dysfunctions in man and in experimental animals. The present study is focused on the effect of lead on the central nervous system, which is considered to be most deleterious, especially alterations of cognitive and behavioral functions. New concepts in the neurotoxicology of lead include advances in understanding mechanisms of lead-induced damage to the nervous system, like induction of oxidative stress. In the experimental part the entry of lead into the brain of mature mice after long-term exposure to lead acetate (PbAc) and the influence of lead on cognitive function and motoric skills of exposed animals were observed. Cognitive function was tested in Morris water maze, motoric tests were performed on rotating cylinder and horizontal wire. Healthy and neurodefective Lurcher mutant mice were used. Further the influence of lead on the development of oxidative stress in the brain by fluorescent spectroscopy was studied. Lipofuscin-like pigments were used as indicators of oxidative stress. The prominent accumulation of lead in the brain of exposed animals as compared to controls was observed after the long-term exposure of mice to PbAc. No changes in motoric or cognitive functions in healthy or...
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Properties of Aerosol, Produced by Laser Ablation of Standard Materials for ICP-MS Analysis.
Holá, M. ; Nováková, H. ; Ondráček, Jakub ; Vojtíšek, M. ; Kanický, V.
Laser ablation (LA), together with inductively coupled plasma mass spectrometry (ICP-MS) as a detection system, has become a routine method for the direct analysis of various solid samples. The product of laser ablation contains a mixture of vapour, droplets and solid particles. All components are finally transported to a plasma by a carrier gas as a dry aerosol including mainly agglomerates of primary nanoparticles. In general, characterisation of aerosols by their particle size distribution (PSD) represents indispensable tool for fundamental studies of the interaction of laser radiation with various materials. The particle size distribution of dry aerosol originating from laser ablation of standard material was monitored by two aerosol spectrometers – Fast Mobility Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS) simultaneously with laser ablation - ICP-MS analysis.\n
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22016102412241 - PDF
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RF coil for MR systém
Vojtíšek, Miloš ; Kořínek, Radim (referee) ; Gescheidtová, Eva (advisor)
The bachelor thesis is focused on radio frequency coils for magnetic resonance imaging systems. Magnetic resonance is used for imaging of many objects, especially human body in medicine, plants and many other different objects. For obtaining optimal results it is essential to use a special suitable coil for every single application. In the first part of this work, the short overview of principles of magnetic resonance imaging is described followed by a look at hardware used in MRI. The main aim of the work is design of several different types of RF coils used in MRI. Finally two suitable designs have been chosen for the purpose. Coils have been realized, tested in experiments. Results were analyzed, maps of generated magnetic field were calculated and homogeneity was determined.
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