National Repository of Grey Literature 85 records found  beginprevious33 - 42nextend  jump to record: Search took 0.00 seconds. 
Photochemical vapor generation of rhenium with a detection by inductively coupled plasma mass spectrometry
Hašlová, Karolína ; Musil, Stanislav (advisor) ; Nováková, Eliška (referee)
This bachelor thesis deals with an optimization of the conditions of photochemical vapor generation of rhenium with detection by inductively coupled plasma mass spectrometry. Photochemical vapor generation was realized using an ultraviolet irradiation in a high-efficiency photochemical reactor with an inner reaction channel from a formic acid based medium in presence of reaction modifiers. Optimizations of parameters affecting the generation efficiency was implemented step by step - reaction medium flow rate (irradiation time), formic acid concentration, addition of acetic acid and reaction modifiers (transition metals) and carrier gas flow rate. The addition of an appropriate combination of reaction modifiers - cadmium(II) and iron(II) ions, had a key impact on photochemical generation of volatile species of Re and led to more than 40-fold increase in generation efficiency. A further (2-fold) increase in generation efficiency was achieved by wrapping the high-efficiency photochemical reactor with an aluminum foil, probably due to more efficient irradiation of the sample in the generator. The limit of detection and quantification were determined as 0.24 ng dm-3 and 0.80 ng dm-3 Re, respectively. The repeatability of the method 100 ng dm-3 Re was 4.8%. Key words photochemical vapor generation,...
Determination of selected metals in tea samples and bag materials
Hlávka, Jan ; Nováková, Eliška (advisor) ; Hraníček, Jakub (referee)
This bachelor thesis is dealing with determination of antimony in materials modern pyramid-shape tea bags. Possible presence of antimony in these materials, e.g. polyethylene terephthalate (PET) or mixed materials, is caused by using it like catalyst in production of polyethylene terphthalete. The goal of this bachelor thesis is the verification of hypothesis, that antimony is present in materials of pyramide tea bags and that it is released to consumed drink, if higher concentration of antimony is present, and that it could pose a health risk to the consumer. At the same time, I studied if tea leaves are contaminated by other toxic elements, from which some can result from intesive agricultural production. They can be used as pesticides or be presnet in industrial fertilizers. In this thesis I examined the content of As, Cd, Cu, Sb and Zn in tea leaves sold in pyramide bags. These pyramide bags were purchased in local supermarkets and shops. The content of Sb in bags was determined too. The applied method included the decomposition of samples in a microwave decomposition device and analysis of the composition of the resulting solution by the ICP-MS method. Determined contents of the investigated elements were expressed like content of element in the sample in dry mass and the results were compared...
Generation of zinc volatile species for determination by atomic spectrometry
Dlouhá, Kateřina ; Nováková, Eliška (advisor) ; Kratzer, Jan (referee)
This diploma thesis deals with the determination of zinc by volatile species generation with detection by atomic absorption or fluorescence spectrometry. Volatile zinc species are generated using hydrochloric acid and sodium borohydride stabilized with sodium hydroxide. Conditions influencing the generation and atomization of volatile species were optimized, namely hydrochloric acid concentration, sodium borohydride concentration, sodium hydroxide concentration, hydrochloric acid flow rate, sample loop volume, reaction coil volume, frit porosity in a gas-liquid separator, argon and hydrogen flow rates, and last, the temperature to which the quartz atomizer is heated. Under the optimal conditions, the detection limit of 33 μg·l−1 and the limit of determination of 110 μg·l−1 were reached. It was found that the addition of various reagents (especially 8-hydroxyquinoline) can increase the generation efficiency. With the addition of 1 % (m/V) 8-hydroxyquinoline to the standard/sample the limit of detection was 4 μg·l−1 and the limit of quantification was 12 μg·l−1 . Using an atomic fluorescence spectrophotometer as the detector, the standard reference material was analyzed and good match with the certified concentration value was found, the certified zinc concentration value in the reference material is...
Job satisfaction of teaching staff at primary and secondary schools in the Vysočina region
Nováková, Eliška ; Tureckiová, Michaela (advisor) ; Šafránková, Jana Marie (referee)
The diploma thesis deals with the job satisfaction of pedagogical employees working in elementary and high schools in the Vysočina Region. The main goal of the thesis is to ascertain how are the pedagogical employees in the elementary and high schools of the Vysočina District overall satisfied with individual aspects of the selected outside factors of job satisfaction. The next goal of the thesis is to compare job satisfaction of pedagogical employees in the individual aspects of the selected outside factors. In the theoretical part, the thesis is focused on the theories of job satisfactions and the relationship between job satisfaction and work performance. Furthermore, the thesis deals with selected outside factors, which influence job satisfaction. The investigation is carried out in the selected elementary and high schools in the Vysočina Region. To obtain the necessary data, a non-standardized questionnaire of job satisfaction was created, which was then filled in by 149 teachers of both elementary and high schools in the Vysočina Region. The statistical compilation of the data showed, that the teachers of the selected elementary and high schools of the Vysočina Region are satisfied in their job. On the other hand, the research confirmed differences in the degree of satisfaction based of the...
UV-photochemical generation of volatile compounds of selenium and tellurium
Nováková, Eliška
The presented thesis deals with UV-photochemical generation of volatile compounds of Se and Te from various species. The aim of the project was to expand the current state of knowledge by the application of photocatalytic reduction of higher oxidation states of Se and Te for the speciation analysis based on UV-photochemical generation of volatile compounds. The first step of the study was the assembly of the apparatus for the photocatalysed UV-photochemical generation of volatile compounds. The material of reactor and the whole experimental set-up were based on literature survey and previous research done in our research group. Experiments were directed towards finding the optimum conditions for generation of volatile compounds of selected model elements Se and Te. Se was studied as the element most commonly determined by the UV-photochemical generation of volatile compounds. Conversely, Te was selected as a model analyte representing elements forming less stable volatile compounds. The second part was the application of the optimised method of photocatalysed UV- photochemical generation of volatile Se compound to the determination of Se in water matrices, liquid certified reference materials and also samples of dietary supplements. TiO2/UV-photochemical generation was also successfully modified to...
The pragmatic competency of students of Japanese - speech act of refusal
Nováková, Eliška ; Kanasugi, Petra (advisor) ; Tirala, Martin (referee)
(in English): This thesis focuses on pragmatic competence of Czech students of Japanese, specifically on the speech act of refusal. The aim is to find out how students differ in comparison to native speakers of Japanese. Another aim is to compare Japanese students based on the length of their stay in Japan, their Japanese proficiency, and the textbook used at the beginner level. The theoretical part describes pragmatic competence, politeness theory, the speech act of refusal and its specifics in Japanese. The practical part focuses at the analysis of refusals from the Discourse Completion Task (DCT) using semantic formulas. Usage of these formulas by native speakers and student are then compared. Found differences from the native speakers are further examined among students according to Japanese proficiency, length of their stay in Japan and textbook used at the begginer level. Finally, the results are summarized.
Determination of Copper in Food Supplements by AAS
Hadbavníková, Alexandra ; Hraníček, Jakub (advisor) ; Nováková, Eliška (referee)
EN This bachelor thesis deals with the determination of copper in the form of copper ions in selected food supplements by atomic absorption spectrometry. The first step of the experiment was to find the optimal measurement conditions for the parameters: beam height above the burner edge, burner horizontal position, fuel flow rate, burner angle and spectral interval width. Subsequently, the calibration dependence was determined and the basic measurement characteristics were calculated: repeatability, sensitivity, limit of detection (0.019 mg dm−3 ) and limit of quantification (0.065 mg dm−3 ) at the burner position 0 ř. Interference studies were performed for the presence of iron, manganese and sodium elements in selected food supplements because of theirs increased concentrations. These selected food supplements were analysed: Spektrum 50, Supradyn Energy Complex, Center from A to iron, GS Extra Strong Multivitamin, Caltrate Plus, DAS Gesunde Plus, A-Z Multispektrum and Calibrum 50 Plus. Selected samples were converted to solutions using three procedures: decomposition in water at room temperature, decomposition in nitric acid at room temperature and decomposition in nitric acid at high temperature. The determination of copper itself was performed using a GBC 933 AA spectrometer and the results...
Produkce alelopatických látek u vybraných bylin a jejich biologická účinnost
Nováková, Eliška
The thesis is focused on the study of allelopathy and allelopathic effects of Ambrosia artemisiifolia and Festuca rubra on selected species of herbs. The first theoretical part describes plants relationships and available information about allelopathy. The second part deals with the influence of Ambrosia artemisiifolia on the growth of Plantago lanceolata, Lotus corniculatus, Arrhenatherum elatius, Festuca rubra, Phacelia tanacetifolia and Pisum sativum in outdoor conditions in different cultivation substrates. The effect of extracts from roots of Festuca rubra and synthetic m-tyrosine on the germination of seeds Ambrosia artemisiifolia was evaluated. The obtained results confirmed the effect of Ambrosia artemisiifolia on the growth of the studied plants and the effect of the tested solutions on germination seeds of Ambrosia.
Comparison of mercury determination by electrochemical or UV-photochemical vapor generation with detection by atomic fluorescence
Šandlová, Petra ; Červený, Václav (advisor) ; Nováková, Eliška (referee)
~ 5 ~ Abstract The functionality of the add-on Millennium Merlin Satellite module towards the PSA Millennium Excalibur atomic fluorescence spectrometer for determination of mercury has been proven. At the same time, the ratios of the average signal to the sample standard deviations of the results of repeated measurements of this module were compared with the mercury determination using an atomic absorption spectrometer ContrAA700 with a radiation source with continuous spectrum and high resolution. In model experiments performed on an atomic absorption spectrometer, the experimental conditions of the cold vapor detection above the level of the elemental mercury were optimized. The flow rate of argon and hydrogen, the temperature of the detection cell and the storage bottle and the mercury evaporation time were optimized. It has been shown that the reduction environment in the detection tube reduces the signal. The need to heat the detection tube up to 650 řC has been surprising. The causes of this phenomenon were discussed and confronted with data from the available literature. Subsequently, the mercury signal was monitored unde roptimal conditions found on the AAS, using an atomic fluorescence PSA Millennium Excalibur spectrometer with an additional Millennium Merlin Satellite unit for mercury...

National Repository of Grey Literature : 85 records found   beginprevious33 - 42nextend  jump to record:
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