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Measurement of gradient magnetic field decay in MR tomograph
Kubásek, Ondřej ; Kubásek, Radek (referee) ; Bartušek, Karel (advisor)
The objective of my thesis is to measure magnetic field gradient decay in an MR tomograph, process and evaluate the data measured and analyse the issue. The theoretical section focuses on the reasons for the gradient distortion which has a negative impact on NMR measuring techniques and it also describes options to eliminate the negative effects, focusing mainly on pre-emphasis filtration. It also lists methods of gradient magnetic field measuring. The practical section contains results of magnetic field decay measurements taken with the tomograph in the Institute of scientific instruments of the Academy of sciences in Brno using the method of instantaneous frequency with and without pre-emphasis compensation. The data are processed with MAREVISI and MATLAB programmes. MATLAB is used to develop a modern method of filtration to eliminate noise in useful signal leading to more accurate measurements of MR magnetic fields. This filtration uses a method of time-dependent variable thresholds and two-channel filter banks. MATLAB is also used to design a programme for approximation of the measured gradient magnetic field decay. The decay must be approximated in order to obtain time constants and the degree of exponential decay, which serve to set up the pre-emphasis compensation.
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Optimization of MR acquisition parameters for the measurement of small objects
Pecháček, Libor ; Přinosil, Jiří (referee) ; Gescheidtová, Eva (advisor)
The subject of my thesis is a design of the methods optimizing, the acquisition of MR signals when small objects measure. The thesis is divided into several parts in order to give a deeper knowledge of the problem. The first part focuses on the theory associated with NMR (Nuclear Magnetic Resonance) and SNR (signal-to-noise ratio). The practical verification of the theory follows. The conclusion of this work is focused on MR images filtering by use of wavelet transform to suppress a noise in the image. The method optimization of MR acquisition parameters for the measurement of small objects is then distributed to the entire work.
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Electromagnetic interference and pacemakers
Kulík, Jindřich ; Richter, Miloslav (referee) ; Havlíková, Marie (advisor)
This thesis deals with electromagnetic compatibility of implantable electro-medical devices using in cardiology. The main aim of this thesis is detection of the resistance of implantable pacemakers (PM) and implantable cardioverter defibrillators (ICD) to the electromagnetic interference. In the first part of this thesis, a function of the heart, which is necessary for understanding of PM and ICD operation, is described. The function and construction of PM and ICD is detailed in the theoretical part as well. The next part is focused on the electromagnetic compatibility. The next part is description of the measurement method and the experimental arrangement used for practical experiments with electromagnetic resistance of PM and ICD.
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Detection methods of energetic materials
Procházka, Michal ; Diviš, Pavel (referee) ; Friedl, Zdeněk (advisor)
A research on current methods of detection of explosives and related materials was made. At first the thesis studies methods of detection and analysis of explosives including chromatographic methods (TLC, GC, HPLC, IC), mass spectrometry and its variations, ion mobility spectrometry and infra-red spectroscopy. Next the attention is placed on detection of explosives in solid phase by X-ray detection, nuclear magnetic and quadrupole resonance and thermal neutron activation. Practical applications of these methods are of great importance in this thesis as well as their usage in the counterterrorist fight.
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ChenomX Based NMR Method for Organic Aerosol Analysis
Horník, Štěpán ; Sýkora, Jan
The suitability of ChenomX was performed on both real atmospheric aerosols and model samples of coal combustion and up to 30 compounds were found in analyzed samples. Most abundant substances were mono- and dicarboxylic acids (formic, acetic, succinic acid) and their derivatives (lactic acid), followed by carbohydrates, anhydro saccharides and sugar alcohols (levoglucosan, fructose, D-threitol) and amines (methylamine, dimethylamine). The real aerosol sample was analyzed also on four different NMR spectrometers (500, 600, 700, 800 MHz) in to order to enhance the resolution and find less abundant substances. The frequencies of the spectrometers were chosen according to the ChenomX database. In the 800 MHz spectrum ca. 50 compounds were identified.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22015100911210 - PDF
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NMR Solution Structure of the Protein PsbQ from Photosystem II.
RATHNER, Petr
The PsbQ protein (16.5 kDa) is an extrinsic protein found in the thylakoid membrane of higher plants and green algae. As a member of the Psb protein family, it is situated in the oxygen evolving center and takes part in the water splitting reaction. The stable oxygen production in photosystem II depends on the cooperation of PsbQ with other photosynthetic proteins, mainly PsbP. In order to identify the possible interaction sites, the tertiary structure in solution has to be determined. Although the X-ray crystallographic structure of PsbQ was determined previously, the conformation of residues 14-33 (so-called "missing link") was still unknown at the onset of this work. The initial backbone assignment as well as a secondary structure estimation were achieved recently. In this thesis the resonance assignment was extended and 15N as well as 13C NOESY-HSQC spectra were recorded to obtain structural constraints. The solution structure was determined using the program CYANA. The results obtained show that, while the four helix bundle domain is nearly identical compared to the available X-Ray crystallographic structure significant deviations occur in the N-terminal region. In particular, the residues 37-41, where a short ?-strand had been proposed in the crystal structure, exhibit high ?-helical propensity.
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