Showing papers by "Peter Kopčanský published in 2011"
TL;DR: The evaluation of the experimental data obtained from small-angle X-ray scattering and ultrasonic attenuation indicates the formation of chain-like aggregates composed of magnetite particles as well as the orientation and sizes of aggregated structures under application of different magnetic-field strengths.
Abstract: The effect of magnetic field on the structure formation in an oil-based magnetic fluid with various concentrations of magnetite particles was studied. The evaluation of the experimental data obtained from small-angle X-ray scattering and ultrasonic attenuation indicates the formation of chain-like aggregates composed of magnetite particles. The experimental data obtained from ultrasonic spectroscopy fit well with the recent theoretical model by Shliomis, Mond and Morozov but only for a diluted magnetic fluid. In this model it is assumed that a dimer is the main building block of a B -field-induced chain-like structure, thus the estimation of the nematic order parameter does not depend on the actual length of the structure. The scattering method used reveals information about the aggregated structure size and relative changes in the degree of anisotropy in qualitative terms. The coupling constant [Formula: see text] , concentrations [Formula: see text] , average particle size d and its polydispersity [Formula: see text] were initially obtained using the vibrating sample magnetometry and these results were further confirmed by rheometry and scattering methods. Both the particles' orientational distribution and the nematic order parameter S were inferred from the ultrasonic measurements. The investigation of SAXS patterns reveals the orientation and sizes of aggregated structures under application of different magnetic-field strengths. In addition, the magnetic-field-dependent yield stress was measured, and a relationship between the yield stress and magnetic-field strength up to 0.5 T was established.
49 citations
TL;DR: In this paper, a poly(ethylene glycol) (PEG)-containing magnetic fluid was prepared and magnetic measurements confirmed superparamagnetic behavior at room temperature, and it was found that a magnetic fluid containing PEG (MFPEG) partially inhibited the growth of cancerous B16 cells at the highest tested dose (2.1mg/ml of Fe 3 O 4 in MFPEG).
40 citations
TL;DR: Magnetically induced optical birefringence (Δ n ) was measured for magnetoferritin (MFer), horse spleen ferritin, and nanoscale magnetite aqueous suspensions as mentioned in this paper.
33 citations
TL;DR: In this article, the structural transitions in ferronematics based on the thermotropic nematic 4-trans-4-hexyl-cyclohexyl isothiocyanato-benzene (6CHBT) are described.
Abstract: In this study, observations of structural transitions in ferronematics based on the thermotropic nematic 4-trans-4′-n-hexyl-cyclohexyl-isothiocyanato-benzene (6CHBT) are described. Droplets of the nematic phase in the isotropic phase were observed in solutions of nematogenic 6CHBT dissolved in phenyl isocyanate and 6CHBT dissolved in phenyl isocyanate and doped with magnetic particles of different shapes (nanorods and chain-like particles). Magneto-dielectric measurements of structural transitions in these new systems enable to estimate of the type of anchoring of the nematic molecules on the magnetic particles surface.
28 citations
TL;DR: In this article, the structural changes in the liquid crystal doped with SWCNT or magnetite-labeled carbon nanotubes (SWCNT/Fe3O4) in electric and magnetic fields were investigated.
Abstract: Stable colloidal suspensions of single-walled carbon nanotubes (SWCNT) and magnetite-labeled SWCNT (SWCNT/Fe3O4) in thermotropic liquid crystal 4-(trans-4′-n-hexylcyclohexyl)isothiocyanatobenzene (6CHBT) were investigated. The presence of the magnetite in SWCNT/Fe3O4 product has been checked with infrared spectroscopy. Transmission electron microscopy has been employed to obtain the structural and dimensional data for the used samples. Magnetic properties of the samples have been investigated by a SQUID magnetometer and a significant increase of the saturation magnetization has been shown for magnetite labeled SWCNT. The structural changes in the liquid crystal doped with SWCNT or SWCNT/Fe3O4 in electric and magnetic fields were investigated. The density of anchoring energy at the nematic–magnetic particle boundary was determined and it was shown that the density of the anchoring energy for liquid crystal doped with SWCNT/Fe3O4 is higher than that for the liquid crystal doped with net SWCNT.
27 citations
04 Jul 2011
TL;DR: The 3D computer simulation of magnetic nanoparticles transport in the blood flow under the influence of a magnetic field was developed in the diffuse programming environment ROOT to calculate the force acting on these particles and to find the conditions under which it is possible to capture the transmitted material and to keep it.
Abstract: The 3D computer simulation of magnetic nanoparticles transport in the blood flow under the influence of a magnetic field was developed in the diffuse programming environment ROOT. This simulation enabled to calculate the force acting on these particles and to find the conditions under which it is possible to capture the transmitted material in the desired area and to keep it, so that the medicinal product could satisfy its therapeutic role at its release.
1 citations