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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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Preparation and characterization of the photocatalytic active TiO2 nanoparticles
Volfová, Lenka ; Nižňanský, Daniel (advisor) ; Lančok, Adriana (referee)
Bachelor thesis Preparation and characterization of the photocatalytic active TiO2 nanoparticles Lenka Volfová 2015, ABSTRACT The present work concerns the preparation of photocatalytically active TiO2 nanoparticles, their characterization and study of their photocatalytic properties. The colloidal solution was obtained by hydrolysis of aqueous solutions of TiOSO4. The samples were lyophilized and the product was annealed at 500 řC, 650 řC, 800 řC and 950 řC. The microstructure, morphology and other characteristics of the products were analysed by several physical and chemical methods: X-ray, EPR, SEM, HRTEM and BET. The measurements of IR, UV/VIS and DTA spectra have also been carried out. Photocatalytic activities were investigated by measurement of kinetics of degradation of 4-chlorophenol or methylene blue aqueous solutions under UV light. Measurement of photocatalytic activity of the samples was compared with the standard Degussa P25. It was found that the efficiency of the samples was higher than the standard. Keywords: hydrolysis, titania nanoparticles, microstructure, photocatalytic activity, photocatalytic degradation
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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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