|
|
A study of non-volatile nitroso compounds in brewing
Malečková, Michaela ; Sobotníková, Jana (advisor) ; Čabala, Radomír (referee) ; Karabín, Marcel (referee)
4 Abstract Nitroso compounds are beer contaminants related to carcinogenicity and can be naturally formed during brewing. They are generally categorized as volatile and non-volatile. Well-characterized and proven carcinogenic compounds are mostly volatile N-nitrosamines, whereas specific non-volatile nitroso compounds are nearly unknown even by structure. This deficiency limits improvements in health-risk assessment and control of beer. The present study focused on these barely known compounds in beer, related to their molecule structures and natural occurrence in beer and malt. Since these compounds form by nitrite reactions with naturally occurring compounds in beer or raw materials, the beer sample was parallelly treated by nitrite and isotopically labelled nitrite-15N at acidic conditions. Due to isotopic labelling, formed nitrite-related reaction products were distinguished by gas chromatography with tandem mass spectrometry. By this approach, up to 22 unknown nitrite-related reaction products (N-products) were found and structurally studied from mass spectrometric fragmentation patterns. Besides previously found N-nitrosoproline and N-nitrosoproline ethyl ester, newly characterized compounds in beer were 4-cyanophenol, pyruvic acid oxime, 2-methoxy-5-nitrophenol, nitrosoguaiacol, and 4-nitrosophenol....
|
|
|
Learning styles of future Biology teachers and scientists
MALEČKOVÁ, Michaela
The diploma thesis deals with the topic of learning styles. The literature review describes the teaching and its conceptions, it works with the term of the teaching methods. The literature review characterizes teaching methods mostly used in biology education. Furthermore, the literature review explains the learning process, the approaches to learning, strategies, and tactics of learning. In the next part, the literature review deals with the learning styles and their classification according to the well-known authors. The last section of the literature review describes the diagnostics of the learning styles and methods that are used for detecting the learning styles. The results summarize the findings of a research study focused on the learning styles of university students. The research dataset consists of 187 cases that reflect the differences in the preferences of learning styles of future scientists and biology teachers and the relationship between a particular learning style and the favourite teaching method that students encountered at primary or secondary school. Furthermore, there were founded out the differences in the preferences of teaching methods and identified the reasons that had led the respondents to study science (biological) disciplines.
|
|
|
Learning styles of pupils in the education of natural history
MALEČKOVÁ, Michaela
The bachelor thesis focuses on the topic of learning styles. There are described learning and some approaches to learning and strategies of learning in the review of literature. The next part of the literary part presents the most famous authors and their theories concerning learning styles of students. The following part applies on diagnostics of learning styles. In the last part there are characterised teaching methods which are used in biology and the signs that teaching methods and learning styles have in common. The practical part and results focused on learning styles of students from 8th and 9th classes from primary schools. The research data set contains 125 cases that reflect differences in learning styles depending on the pupil's gender or whether certain learning styles are related to biology. It is found whether a certain favourite area of biology (f. e. biology of human body, zoology, botany ...) is related to a learning style, whether the teaching method affects the popularity of biology, or whether a certain learning style is related to the teaching methods and forms in biology.
|
|
|
Development of miniaturized extraction method used for GC-NCD screening of non-volatile nitroso compounds in malt
Malečková, Michaela ; Sobotníková, Jana (advisor) ; Kameník, Zdeněk (referee)
The aim of this diploma thesis was to develop a miniaturized extraction method for a fast screening of non-volatile nitroso compounds using gas chromatography with a nitroso specific chemiluminescence detection. According to a final methodology, the samples were prepared by extraction of grinded malt using a mixture of pyridine and acetonitrile in ratio 60:40 (v/v). To enhance volatility of the determined analytes, the two-step derivatization using hexamethyldisalazane and N,O-bis(trimethyl)-trifluoroacetamide was used. The total volume of the sample was 200 l and the preparation time after optimization was in total 80 min. The extraction method was connected to a classification method, which can divide chromatographic peaks into the groups of N-nitroso and C-nitroso compounds, and interfering substances. After application of the methods mentioned above to real malt samples, the specific chromatographic peaks of C-nitroso and N-nitroso compounds were selected. Description of their properties and structure suggestion will be a subject of the following study. Keywords Nitroso compounds, malt, extraction, derivatization, gas chromatography, chemiluminescence detector
|
|
| |
|
|
Hippoterapie a zahrada
Malečková, Michaela
The work shows the possibilities of creating landscapes suitable for recreation and hippotherapy, while preserving the values of landscape in the area of Těmice. It is trying to show how to make the design of the chosen estate gently to the environment. It deals with a water problems, such as meliorations that were made at the end of the last century and the loss of permanent grasslands.
|
|
|
Development of miniaturized extraction method used for GC-NCD screening of non-volatile nitroso compounds in malt
Malečková, Michaela ; Sobotníková, Jana (advisor) ; Kameník, Zdeněk (referee)
The aim of this diploma thesis was to develop a miniaturized extraction method for a fast screening of non-volatile nitroso compounds using gas chromatography with a nitroso specific chemiluminescence detection. According to a final methodology, the samples were prepared by extraction of grinded malt using a mixture of pyridine and acetonitrile in ratio 60:40 (v/v). To enhance volatility of the determined analytes, the two-step derivatization using hexamethyldisalazane and N,O-bis(trimethyl)-trifluoroacetamide was used. The total volume of the sample was 200 l and the preparation time after optimization was in total 80 min. The extraction method was connected to a classification method, which can divide chromatographic peaks into the groups of N-nitroso and C-nitroso compounds, and interfering substances. After application of the methods mentioned above to real malt samples, the specific chromatographic peaks of C-nitroso and N-nitroso compounds were selected. Description of their properties and structure suggestion will be a subject of the following study. Keywords Nitroso compounds, malt, extraction, derivatization, gas chromatography, chemiluminescence detector
|
|
| |
|
|
Návrh sbírkové zahrady kapradin
Malečková, Michaela
The main aim of this work is to show the fern as a valuable part of modern gardens and their importance in the composition, as well as their basic botanical characteristics . The work deals with the summary of current knowledge of the literature in the area of cultivation , ecology and biology of ferns. I present here the basic growing claims on the use of ferns in the garden and landscape architecture. An essential part of the work is also designing collection garden of ferns. The main finding is that is possible (with some restrictions) to create a garden composed from ferns, but should be complemented by other plant species.
|
guest ::
RSS feed.