|
|
Centra rekombinace v semiizolačním CdTe
Zázvorka, Jakub ; Franc, Jan (advisor) ; Fiederle, Michael (referee)
Title: Recombination centers in semiinsulating CdTe Author: Jakub Zázvorka Department / Institute: Institute of Physics of Charles University Supervisor of the master thesis: prof. Ing. Jan Franc, DrSc., Institute of Physics of Charles University Abstract: The properties of CdTe for application as a radiation detector are influenced through the presence of deep levels in the bang gap. These energy levels complicate the charge collection and the detector efficiency. Contactless resistivity mapping (COREMA) represents a good option for material characterization without the necessity of metal contacts application. The time-dependent charge measurement was investigated on an adjusted apparatus in FMF Freiburg. Theoretical model of charge transport based on band bending on the sample surface was proposed and a non-exponential behavior was calculated. Using this, the resulted parameter tendencies and their connection with deep level trap or recombination center were explained. A correlation was observed between resistivity, photoconductivity and a near midgap level photoluminescence. Parameter profiles were explained using the theory of Fermi level shift relative to the near midgap level. Three deep levels were observed on samples grown at the Charles University in Prague. Their photoluminescence supports the...
|
|
|
Recombination between the gene and pseudogene for glucocerebrosidase as a mechanism of mutation generation in Gaucher disease
Peková, Barbora ; Hřebíček, Martin (advisor) ; Schierová, Michaela (referee)
Gaucher disease is an autosomal recessive disorder caused by the deficiency of β-glucocerebrosidase. Some Gaucher patients carry in their β-glucocerebrosidase genes complex mutations which apparently arose by a recombination with the non-functional β-glucocerebrosidase pseudogene. Recombination between genes and their corresponding pseudogenes plays a role in the development of other hereditary human diseases. Mutant alleles formed in male and female meiosis are a source of these variations in the gene pool. The study of frequency and scope of recombination events in human disease-associated genes in the gametes is of importance for evaluation of the disease burden in the population. The evaluation of the scope of single recombination events in the β-glucocerebrosidase gene in human gametes is technically challenging. Novel technologies such as next-generation sequencing, nanopore sequencing or droplet digital PCR may have advantages over previously used techniques in this application. Key words: recombination, gene conversion, pseudogene, β-glucocerebrosidase, complex alleles, Gaucher disease
|
|
|
Electron Ion Recombination in Low Temperature Plasma
Dohnal, Petr ; Glosík, Juraj (advisor)
The presented work focuses on study of electron - positive ion recombination in low temperature plasma. The principal method used were Flowing afterglow with Langmuir probe and Stationary afterglow with Cavity Ring-Down Spectrometer. For the first time electron and neutral assisted collisional radiative recombination of Ar+ ions was studied in temperature range of 50 - 200 K. Resulting ternary recombination rate coefficients are in good agreement with theoretical predictions. Recombination of H3 + and D3 + ions with electrons was studied in the temperature range of 50 - 300 K and binary and ternary recombination rate coefficients were obtained. The effect of nuclear spin on recombination of H3 + ions with electrons was studied in the temperature range of 80 - 200 K and state selective recombination rate coefficients were obtained for ortho- and para-H3 + . Results show that at 80 K para-H3 + recombines with electrons substantially faster than ortho-H3 + .
|
|
|
Recombination centers in semiinsulating CdTe
Zázvorka, Jakub
Title: Recombination centers in semiinsulating CdTe Author: Jakub Zázvorka Department / Institute: Institute of Physics of Charles University Supervisor of the master thesis: prof. Ing. Jan Franc, DrSc., Institute of Physics of Charles University Abstract: The properties of CdTe for application as a radiation detector are influenced through the presence of deep levels in the bang gap. These energy levels complicate the charge collection and the detector efficiency. Contactless resistivity mapping (COREMA) represents a good option for material characterization without the necessity of metal contacts application. The time-dependent charge measurement was investigated on an adjusted apparatus in FMF Freiburg. Theoretical model of charge transport based on band bending on the sample surface was proposed and a non-exponential behavior was calculated. Using this, the resulted parameter tendencies and their connection with deep level trap or recombination center were explained. A correlation was observed between resistivity, photoconductivity and a near midgap level photoluminescence. Parameter profiles were explained using the theory of Fermi level shift relative to the near midgap level. Three deep levels were observed on samples grown at the Charles University in Prague. Their photoluminescence supports the...
|
|
|
Recombination hot-spots in various organisms
Stočesová, Lucie ; Holá, Dana (advisor) ; Forman, Martin (referee)
Meiotic recombination is an important process which occurs in sexually reproducing organisms and creates new allelic combinations. Frequency and distribution of crossing-overs (COs) are affected by many internal and external factors. Regions with higher frequency of COs are called recombination hot-spots and in this thesis, they are divided into ancestral and derived hot-spots. Ancestral hot-spots are the more original ones and they are determined by histone modifications, nucleosome-depleted regions, promoters and sequence motifs. This type of hot-spots occurs, e.g., in yeasts, birds and plants. Derived hot-spots are determined by the PRDM9 protein, which searches for specific sequence motifs and creates histone modifications. These hot-spots are typical for most mammals except the canines which lost functional PRDM9 due to the mutation of the Prdm9 gene. Activity of PRDM9 destroys primary locations of hot- spots via gene conversion. This process is called "hot-spot paradox" and is solved by the rapid evolution of alleles of the Prdm9 gene. This thesis summarizes basic information on distribution and determination of hot-spots among various eukaryotes. It particularly focuses on the PRDM9 protein, its structure, function and evolution. A determination of location of recombination in species...
|
|
|
Knowledge and Opinions of Students on Genetically Modified Organisms
Semencová, Barbora ; Hlaváčová, Lucie (advisor) ; Vojíř, Karel (referee)
This diploma thesis is focused on topic of genetically modified organisms and their use in the practical sectors of human life. Theoretical part of the thesis defines general terms GMO, plasmid, genetic engineering, biotechnology. It also records historical milestones relating to the problematic, deals with individual techniques of genetic engineering and briefly states legislative procedures in context of dealing with GMO. It gives examples of transgenic organisms and summarizes advantages and disadvantages of their use.Practical part of the thesis contains educational program called "Genetically modified organisms", which was conceived by the author and includes a draft of a lesson inclusive of teaching materials - powerpoint presentations, worksheets, interactive worksheets, auxiliary text for teacher and written preparation. Research part deals with high school students change of view about using GMOs after completing the educational program. Due to analysis was proven that most of the attitudes and knowledge about GMO was changed after completing the educational program (for example in issues of willingness to consume GM food and animal products, perception of advantages and disadvantages etc.) Data was still unchanged in questions which cannot be affected by the program (control of food packaging or...
|
|
| |
|
|
Electron Ion Recombination in Low Temperature Plasma
Dohnal, Petr ; Glosík, Juraj (advisor)
The presented work focuses on study of electron - positive ion recombination in low temperature plasma. The principal method used were Flowing afterglow with Langmuir probe and Stationary afterglow with Cavity Ring-Down Spectrometer. For the first time electron and neutral assisted collisional radiative recombination of Ar+ ions was studied in temperature range of 50 - 200 K. Resulting ternary recombination rate coefficients are in good agreement with theoretical predictions. Recombination of H3 + and D3 + ions with electrons was studied in the temperature range of 50 - 300 K and binary and ternary recombination rate coefficients were obtained. The effect of nuclear spin on recombination of H3 + ions with electrons was studied in the temperature range of 80 - 200 K and state selective recombination rate coefficients were obtained for ortho- and para-H3 + . Results show that at 80 K para-H3 + recombines with electrons substantially faster than ortho-H3 + .
|
|
|
The role of H3K36 methylation in DNA repair of germinal and somatic cells
Křivánková, Klára ; Mihola, Ondřej (advisor) ; Schierová, Michaela (referee)
Histone modifications affect many cellular processes including DNA damage repair. This thesis focusses on the methylation of lysine 36 of histone 3 (H3K36). The role of this modification in the localization of DNA double-stranded breaks in germinal cells is described in the first part of this thesis. Double-stranded breaks initiate meiotic recombination, which is essential for successful meiosis. This thesis also describes three histone methyltransferases. The first is PRDM9, an enzyme expressed only in oocytes and spermatocytes during meiotic prophase and responsible for the localization of recombination hotspots in most mammals. The second part of this thesis deals with the role of H3K36 methylation in DNA damage repair in somatic cells using homologous recombination (HR) and nonhomologous DNA ending joining (NHEJ). The proteins SETD2 and SETMAR are described in the second part. SETD2 trimethylates H3K36, and H3K36me3 is recognized by the LEDGF protein. Through LEDGF, other components necessary for HR are recruited to DNA. SETMAR dimethylates H3K36 and together with this histone modification promote DNA break repair with NHEJ. The research of H3K36 methylation is important for a better understanding of each DNA repair mechanisms. The correct repair of DNA breaks is necessary for maintaining...
|
|
| |
guest ::
