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Study of hyperfine interactions in nanoparticles present in biological systems
Kubániová, Denisa ; Kohout, Jaroslav (advisor) ; Závěta, Karel (referee)
In the submitted bachelor thesis we studied iron oxides by zero-field and in-field Mössbauer spectroscopy at room and liquid helium temperature. The relative composition in synthe- tically prepared nanoparticles of ferric oxide in SiO2 matrix is investigated in dependence on ferric oxide concentration and heating temperature and further the phase composi- tion and structure of biological nanoparticles produced by Geoalkalibacter ferrihydriticus bacteries in dependence on concentration of quinone in the cultivating solution. By data analysis the chemical and phase composition of the samples and hyperfine parametres of 57 Fe cations in nonequivalent crystallographic positions are determined. 1
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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....
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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....
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Study of hyperfine interactions in nanoparticles present in biological systems
Kubániová, Denisa ; Kohout, Jaroslav (advisor) ; Závěta, Karel (referee)
In the submitted bachelor thesis we studied iron oxides by zero-field and in-field Mössbauer spectroscopy at room and liquid helium temperature. The relative composition in synthe- tically prepared nanoparticles of ferric oxide in SiO2 matrix is investigated in dependence on ferric oxide concentration and heating temperature and further the phase composi- tion and structure of biological nanoparticles produced by Geoalkalibacter ferrihydriticus bacteries in dependence on concentration of quinone in the cultivating solution. By data analysis the chemical and phase composition of the samples and hyperfine parametres of 57 Fe cations in nonequivalent crystallographic positions are determined. 1
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