National Repository of Grey Literature 59 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Relaxivity of magnetic nanoparticles
Kubíčková, Lenka ; Kohout, Jaroslav (advisor) ; Lančok, Adriana (referee)
Magnetic nanoparticles have found broad applications in medicine, in particular as contrast agents for T1- and T2-weighted magnetic resonance imaging (MRI). The ability of a contrast agent to influence the proton relaxation rate in a tissue is described by its relaxivity. In the submitted bachelor thesis we characterise physical properties of samples of ε-Fe2O3 nanoparticles coated with amorphous silica (SiO2), particularly with the aim to determine the dependences of their relaxivities on the magnetic field, temperature and thickness of silica coating. The distribution of the particle sizes was derived from the TEM pictures giving the median ~ 20 nm and the thickness of the silica coating ~4; 8; 13; 19 nm. The lattice parameters and presence of ˂ 2% admixtures of α phase were ascertained by XRD analysis; hyperfine parameters obtained by Mössbauer spectroscopy indicate no change of magnetic properties of the particles by silica coating. The relative amount of ε-Fe2O3 and SiO2 in the samples was specified from the magnetic measurements. Aqueous suspensions of different concentrations of coated nanoparticles were prepared, and their relaxivities r1, r2 were measured in different magnetic fields. Temperature dependence of relaxivities of a chosen sample was obtained in fields 0.47 T and 11.75 T....
Fast Dynamic Processes in Solution Studied by NMR
Šoltésová, Mária ; Lang, Jan (advisor) ; Mäler, Lena (referee) ; Batta, Gyula (referee)
Title: Fast Dynamic Processes in Solution Studied by NMR Spectroscopy Author: Mária Šoltésová Department: Department of low temperature physics, Charles University in Prague, and Department of Materials and Environmental Chemistry, Stockholm University Supervisor: doc. RNDr. Jan Lang, Ph.D., Department of low temperature physics, Charles University in Prague, and Prof. Jozef Kowalewski, Department of Materials and Environmental Chemistry, Stockholm University Abstract: Nuclear magnetic resonance (NMR) spectroscopy is capable to deliver a detailed information about the dynamics on molecular level in a wide range of time scales, especially if accompanied by suitably chosen theoretical tools. In this work, we employed a set of high-resolution NMR techniques to investigate dynamics processes in several weakly interacting molecular systems in solution. Van der Waals interactions play an important role in inclusion complexes of crypto- phane-C with chloroform or dichloromethane. The complex formation was thoroughly investigated by means of 1H and 13C NMR experiments along with the quantum- chemical density functional theory (DFT) calculations. We characterized kinetics, thermodynamics, as well as fine details of structural rearrangements of the complex formation. Internal dynamics of oligo- and...
Expression, characterisation and biological role of Ddi II, putative protein partner of proteasomal complex
Sivá, Monika ; Konvalinka, Jan (advisor) ; Obšil, Tomáš (referee)
Cell homeostasis is maintained via strictly regulated processes. One of the important regulation systems is ubiquitin-proteasome proteolytic pathway. Proteins to be degraded are posttranslationally modified with polyubiquitin chains and targeted to the proteasome for degradation. Ubiquitin-proteasome system consists of several processes: ubiquitination of target substrates via set of enzymes, substrate transfer and degradation in the 26S proteasome. There are two ways of ubiquitinated substrate recognition via proteasome. It is either directly by proteasomal receptors or by protein shuttles. Shuttling factors bind polyubiquitinated target substrate and transfer it to the entrance of proteasomal cavity thanks to their typical domain architecture. The N-terminal ubiquitin-like domain binds to regulatory particle of the proteasome and the C-terminal ubiquitin-associated domain binds polyubiqitinated chains on substrates. This thesis focuses on the human DNA damage-inducible protein homolog 2 (Ddi2), a potential member of protein shuttles of humans, and on the interaction of its ubiquitin-like domain with its putative interaction partner, a proteasomal subunit PSMD2. PSMD2 has been cloned, expressed and purified in sufficient yields for further experiments. "Cold" as well as isotopically labeled UBL domain of...
Development of analytical methods for determination of phosphorylated components of bacterial cell membranes
Mikulecká, Jana ; Čabala, Radomír (advisor) ; Feltl, Ladislav (referee)
Phospholipids are dominant components of bacterial cell membranes, where they create double layers. Bacteria differ in their phospholipid composition determination of which can help in identification of important groups of microorganisms. Phospholipid composition of bacteria is influenced by many environmental factors, therefore its variation can be observed within one bacterial stem also. Because of its simplicity, thin layer chromatography is usually applied to identification and determination of bacterial phospholipids. Disadvantage of this method are the high demands of time, carefulness and skills of the analytical personnel. The increasing interest in the phospholipid double-layer promotes the detailed investigation of their fatty acid composition because the more detailed analyses allows for more information yield about bacteria. Gas chromatography hyphenated with mass spectrometry seems to be the best choice for these purposes. Fatty acid identity and total fatty acid content in phospholipid molecules could be determined by this method. Additionally, number, position and isomerism of double bonds and presence of other functional groups on hydrocarbon chain could be determined. Whereas a suitable and...
Měření C-13 NMR relaxací karbonylových skupin v proteinech
Grocký, Marián ; Hrabal, Richard (referee)
Title: Measurement of 13 C NMR relaxation of Carbonyl Groups in Proteins Author: Marián Grocký Department: Department of Low Temperature Physics Supervisor: RNDr. Jan Lang, PhD. Supervisor's email address: Jan.Lang@mff.cuni.cz Abstract: I have investigated measurement methods of 13 C NMR longitudial and transversal relaxation constants in proteins labeled by 13 C, 15 N. The Mason-Pfizer Matrix protein (M-PMV) has been studied in it's wild form (WT) and mutated form (R55F) by these methods in order to reveal its dynamics. It has been known that point mutation of arginine for phenylalanine at the 55th position of matrix protein changes virus's life cycle. Reproduction of M-PMV than resembles HIV virus reproduction. Nitrogen T1, T2 and NOE relaxation experiments have also been carried out. All relaxation data were used for Lipari-Szabó model-free approach in order to get and compare carbonyl and amide group motion parameters. There has been found a high similarity between carbonyl and nitrogen motion parameters within WT protein. Nitrogen data of R55F protein approved higher mobility of particular sequences in that protein, which is assumed to be responsible for changes in mutant's life cycle. Both carbonyl and nitrogen data significantly enlarged our current knowledge of dynamics of both WT and R55F...
Application of modern analytical methods for the study of selected boron coordination compounds
Hrušková, Helena ; Jelínek, Ivan (advisor) ; Dian, Juraj (referee)
This thesis is focused on the study of boron coordination compounds, specifically boron pyrogallol and 2,3-dihydroxynaphthalene ligand complexes. In the introductory part of the work are discussed the properties of boron compounds, their preparation, the possibility of separation by capillary electrophoresis and methods of structural characterization. In the first part of the thesis, the methods of preparation of complexes are discussed and for each complex the optimal yield response is chosen. The resulting products were studied by low resolution mass spectrometry. In the second part of the thesis, structures of complexes, including their modeling in the Gaussian program, were described more precisely. Furthermore, the complexes were characterized by high resolution mass spectrometry. The complexes were also studied by 11 B, 1 H and 1 H COSY NMR and IR spectroscopy. The third part was devoted to the separation of these substances from the mixture after the reaction. CE-UV and CE-MS techniques were used for this purpose. To convert the results, the separation method was developed in ammonium formate buffers that are compatible with both instruments. The equilibration between complexes and ligands was also monitored by CE-UV. A special chapter is the study of pyrogallol autooxidation by UV-VIS and...
Nanoparticles based on block copolymer complexes with fluorosurfactants
Škvarla, Juraj ; Štěpánek, Miroslav (advisor) ; Netopilík, Miloš (referee)
This thesis deals with (i) complex nanoaggregates of cationic perfluorinated surfactant N-(1,1,2,2- tetrahydroperfluorodecyl)pyridinium chloride and of double hydrophilic block polyanions poly(ethylene oxide)-b-poly(methacrylate) and poly(ethylene oxide)-b-poly((2-sulfamate-3- carboxylate)isoprene), and with (ii) mixed micelles of amphiphilic copolymer poly(ethylene oxide)- b-poly(e-caprolactone) and nonionic perfluorinated fluorosurfactant Zonyl FSN-100. The study was aimed at the characterization of the association behavior of the block copolymer-fluorosurfactant systems in aqueous solutions depending on the amount of the added surfactant, pH of the solvent and the structure of the copolymers.
Study of LaCuAl3 structure by means of nuclear magnetic and quadrupole resonance
Sgallová, Ráchel ; Chlan, Vojtěch (advisor) ; Englich, Jiří (referee)
In the presented bachelor thesis the structure of LaCuAl3 was studied on a series of metallic powder samples LaCuxAl4−x, x = 0,75; 0,9; 1 and 1,1 especially with respect to the local symetry of La atoms. 63 Cu, 65 Cu, 27 Al and 139 La nuclear magnetic resonance spectra were measured at room tempera- ture in external magnetic eld of 9,4 T. Some of the measured spectra were compared with simulated ones in order to access the number of nonequiva- lent atoms in the structure. Furthermore, the effect of Al/Cu stoichiometry on nuclear magnetic resonance spectra was observed and diccussed. 1
Alternative synthesis of of 1-(diphenylphosphino)-1'-(N,N-dimethylaminomethyl)ferrocene
Zábranský, Martin ; Štěpnička, Petr (advisor) ; Vojtíšek, Pavel (referee)
An alternative, more straightforward and effective method for the preparation of 1- (diphenylphosphino)-1'-(N,N-dimethylaminomethyl)ferrocene was developed using 1-bromo- 1'-(diphenylphosphino)ferrocene as the starting material and Eschenmoser's salt as an aminomethylation agent. Purity of thus prepared phosphinoamine was verified by 1 H and 31 P NMR spectroscopy and by comparison of the data with those reported in the literature (M. E. Wright, Organometallics, 1990, 9, 853). The coordination chemistry of this compound was investigated in gold(I) complexes. Thus, chlorido[1-(diphenylphosphino)-1'-(N,N-dimethyl- aminomethyl)ferrocene]gold(I) complex was synthesized and converted to ill-defined [1- (diphenylphosphino)-1'-(N,N-dimethylaminomethyl)ferrocene]gold(I) perchlorate by halogen abstraction with AgClO4. Protonization of the nitrogen atom in both compounds with hydrogen chloride yielded the corresponding hydrochlorides. It was shown that 1- (diphenylphosphino)-1'-(N,N-dimethylaminomethyl)ferrocene is coordinated as a simple phosphine in the resulting complexes while its amine nitrogen is protonated. All these complexes were characterized by means of 1 H, 31 P and 13 C NMR spectroscopy, mass spectroscopy with electrospray ionisation, elemental analysis and by single-crystal X-ray diffraction analysis.

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