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    Wyświetlanie 1-15 z 15
    Tytuł:
    The Effect of Polymer Immobilization on Magnetic Properties of Magnetosomes
    Autorzy:
    Timko, M.
    Džarová, A.
    Kovač, J.
    Kopčanský, P.
    Gojzewski, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535115.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    75.30.Gw
    75.50.Mm
    75.50.Tt
    75.60.Ej
    Opis:
    The anisotropy of several PVA/magnetosomes magnetically textured films has been investigated from the point of view of magnetic properties. The thin film synthesized under the influence of a magnetic field (99 mT) shows the typical behavior of an anisotropic material. On sample textured in magnetic field the magnetisation loop measurements were performed in dependence on the direction of the external magnetic field with respect to the texture axis. The results of hysteresis measurements show that the magnetic field applied during the synthesis promotes an orientation of the chains of magnetosomes and permanently textured film is obtained after solidification. The obtained values for magnetic remanence and coercivity were dependent on the external magnetic field orientation and the alignment effect of particle moments may be clearly seen which is in agreement with the theoretical model of magnetic particle chains.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 995-997
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Composites Consisting of High-T$\text{}_{c}$ Superconductor and Fine Magnetic Particles
    Autorzy:
    Timko, M.
    Kopčanský, P.
    Kováč, J.
    Koneracká, M.
    Plecháček, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/2013009.pdf
    Data publikacji:
    2000-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    74.72.Hs
    75.50.Tt
    Opis:
    The composite systems as a mixture of fine magnetic particles of Fe$\text{}_{3}$O$\text{}_{4}$ and superconducting powder such as Bi$\text{}_{1.8}$Pb$\text{}_{0.2}$Sr$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{10+x}$ were prepared. The influence of internal magnetic field (generated by magnetic particles) on the superconducting properties of prepared composites were studied as a function of concentration of magnetic particles and their magnetic state. The observed data both of the shielding and the Meissner effect were compared with corresponding linear combination of pure signals of magnetite and superconductor, respectively. The large differences were observed for demagnetized samples. It means that result must be discussed in the frame of the distribution of internal magnetic field created by the magnetic particles.
    Źródło:
    Acta Physica Polonica A; 2000, 97, 3; 389-392
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Characterization of Magnetoferritin
    Autorzy:
    Mitróová, Z.
    Melníková, L.
    Kováč, J.
    Timko, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429123.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.30.Cr
    75.50.Ee
    75.60.Ej
    75.50.Tt
    Opis:
    The paper presents detailed experimental study of synthesis and characterization a bioinorganic magnetic molecule - magnetoferritin. Magnetoferritin with loading of iron ions per protein molecule in the range from 300 to 3000 was prepared. Size distribution analysis (transmission electron microscopy, dynamic light scattering) shows spherical nanoparticles with particle size distribution from 2 to 12 nm, and hydrodynamic diameter from 12 to 25 nm. The thermomagnetic curves measured after cooling the sample in zero field (zero-field cooling) and under the presence of the measurement field (field cooling) show superparamagnetic behavior with the blocking temperature $T_{b}$ from 22 to 60 K and the magnetization loops measured below $T_{b}$ (at 2 K) show the hysteresis with coercive field from 20 to 30 kA/m depending on the concentration of the magnetic nanoparticles.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1318-1320
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Preparation and Complex Characterization of Magnetic Nanoparticles in Magnetic Fluid
    Autorzy:
    Kubovčíková, M.
    Antal, I.
    Kováč, J.
    Závišová, V.
    Koneracká, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201928.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.Fk
    78.67.Bf
    36.40.Cg
    47.65.Cb
    75.50.Mm
    75.30.Cr
    Opis:
    This paper deals with the preparation and complex characterization of magnetite nanoparticles (MNPs), stabilized with sodium oleate (SO), by the routine methods such as infrared spectroscopy (FTIR), magnetic measurements, scanning electron microscopy (SEM) and dynamic light scattering (DLS). The FTIR spectra showed that SO molecules were linked to MNPs through chemical bonding. Magnetic measurements proved that the MNPs are superparamagnetic in nature. Four different methods were used to determine the size and size distribution of the MNPs: SEM, DLS, differential centrifugal sedimentation (DCS) and magnetic measurements. SEM analysis showed a relatively narrow size distribution of roughly spherical MNPs with a mean diameter of 61 nm. DLS analysis confirmed monodispersed MNPs production with hydrodynamic diameter of 75 nm. The size distribution determined by DCS was found to be 69 nm. Finally, the calculated magnetic core diameter obtained from magnetization curve was 10 nm. The obtained results demonstrate that SO coated MNPs fulfil the requirements for a useful drug delivery system.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 268-269
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of Carbon Nanotubes
    Autorzy:
    Jeníková, M.
    Zakuťanská, K.
    Kováč, J.
    Girman, V.
    Kopčanský, P.
    Tomašovičová, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032760.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.48.De
    74.25.nd
    68.37.Lp
    75.75.-c
    Opis:
    The aim of the presented work was to characterize single-walled carbon nanotubes as well as multi-walled carbon nanotubes by transmission electron microscopy, the Raman spectroscopy and magnetization measurements to obtain information about their size, structure, and magnetic properties. We show that having different carbon nanotubes one can easily distinguish the single-wall or multi-wall carbon nanotubes and determine their quality. The obtained results show that carbon nanotubes can be diamagnetic or ferromagnetic depending on their structural parameters.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 952-954
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Bacterial Nanoparticles
    Autorzy:
    Timko, M.
    Džarová, A.
    Kováč, J.
    Kopčanský, P.
    Gojzewski, H.
    Szlaferek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810601.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    51.60.+a
    75.30.Gw
    75.50.Tt
    75.60.Nt
    75.60.Ej
    75.75.+a
    Opis:
    The objective of this study is to prepare and study magnetic properties of biological magnetic nanoparticles (magnetosomes) as a product of biomineralization process of magnetotactic bacteria Magnetospirillum sp. AMB-1. From temperature dependence of remanent magnetization and coercive field the Verwey transition is clearly seen at 105 K as a consequence of the large anisotropy along the chains of magnetosomes.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 381-383
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Birefringence Study of the Magnetic Core Structure of Ferritin
    Autorzy:
    Koralewski, M.
    Pochylski, M.
    Mitróová, Z.
    Melníková, L.
    Kováč, J.
    Timko, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428622.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.20.Ls
    87.15.-v
    87.85.jf
    Opis:
    Magnetically induced optical birefringence (Δ n) was measured for magnetoferritin and horse spleen ferritin aqueous suspensions. The Δ n for magnetoferritin was described in the frame of the Langevin formalism taking into account distribution of core diameter. The established average magnetic dipole moment and core diameter is equal to about 460 $μ_{B}$ and 3 nm, respectively. It was shown that magnetic birefringence and the Cotton-Mouton constant can be powerful parameters in identification of the magnetic core structure of ferritin, especially useful in biomedicine.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1237-1239
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration
    Autorzy:
    Tóthová, J.
    Kováč, J.
    Kopčanský, P.
    Rajňák, M.
    Paulovičová, K.
    Timko, M.
    Józefczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1201929.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    07.55.Jg
    75.50.Mm
    83.85.Jn
    Opis:
    In this work we have studied the effect of temperature on the viscosity of magnetic fluids (MFs) based on the transformer oil ITO 100. The volume concentration of suspended magnetic particles (MPs) changed from 0.25 to 1%. Rheological characterization of MFs was performed using a vibroviscometer at working frequency of 30 Hz. The temperature dependence of the viscosity was measured in the temperature range from 20 up to 50 °C. The magnetization of different concentrations of MPs in MFs was determined by using the vibrating sample magnetometer.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 278-279
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical Properties of Magnetite Nanoparticles Covered by 11-Mercaptoundecanoic Acid
    Autorzy:
    Timko, M.
    Kopčanský, P.
    Antalik, M.
    Simsikova, M.
    Valusova, E.
    Molcan, M.
    Kováč, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429127.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    85.70.-w
    75.30.Cr
    75.47.Lx
    Opis:
    We have investigated the magnetic behavior of magnetite nanoparticles covered by the 11-mercaptoundecanoic acid around magnetite core prepared by a standard co-precipitation method. The particles show superparamagnetic behavior at room temperature, with transition to a blocked state at blocking temperature 91 K estimated from zero field cooled and field cooled at 500 Oe experiment. The hysteresis loop measured at 293 K showed magnetization 32.8 emu/g at 50 kOe without any coercivity. The mean particle size (7.1 nm) was determined by fitting a magnetization curve obtained at 295 K assuming a log-normal size distribution.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1321-1323
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    AC Magnetic Susceptibility of Ferrofluids Exposed to an External Electric Field
    Autorzy:
    Rajňák, M.
    Dolník, B.
    Kováč, J.
    Paulovičová, K.
    Mitróová, Z.
    Kurimský, J.
    Cimbala, R.
    Kopčanský, P.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032260.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    47.65.Cb
    75.75.Fk
    75.78.-n
    83.60.Np
    Opis:
    It is known that ferrofluid superparamagnetic nanoparticles response to external magnetic fields, often resulting in the formation of elongated clusters along the field. This has a notable impact on dielectric properties of ferrofluids. Here we report on indications of a contrary effect when the magnetic susceptibility of ferrofluids based on transformer oil is influenced by an external electric field. This effect is associated with structural changes in the ferrofluids induced by the external electric fields. Particularly, we focus on a steady state electric field effect, which gives rise to forces acting on the magnetite nanoparticles, leading to the formation of aggregates. In this condition we have measured the ferrofluid AC magnetic susceptibility in parallel and perpendicular configuration of magnetic and electric fields at room temperature. The measurements in both configurations yielded a noticeable decrease in the real susceptibility values with increasing electric field intensity. The result is believed to be caused by the reduction in the total magnetic moment of the ferrofluid. This can be a consequence of the superspin interactions in the aggregates, minimizing the aggregate's energy. Finally, we highlight the necessity of NMR and small angle scattering of polarized neutrons investigations in order to obtain exact information on the magnetic structure induced by the electric forces.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 887-889
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiation Stability of the BSA Modified Biocompatible Magnetic Fluid
    Autorzy:
    Tomašovičová, N.
    Haysak, I.
    Kováč, J.
    Kubovčíková, M.
    Závišová, V.
    Timko, M.
    Okunev, A.
    Zorkovská, A.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368667.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    64.70.Md
    Opis:
    The aim of the presented work was to investigate the stability of biocompatible magnetic fluid, i.e. water-based magnetic fluid containing magnetite nanoparticles stabilized by surfactant sodium oleate and modified by bovine serum albumin (BSA) after electron irradiation. Samples with the same concentration of $Fe_{3}O_{4}$ but different mass ratio BSA/$Fe_{3}O_{4}$ (w/w=0.25, 1.0 and 2.5) were studied. The electron irradiation caused about 10% reduction of the saturation magnetization in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 0.25 and less than 5% in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 1 and 2.5.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 262-263
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Magnetite Formed by Biomineralization and Chemical Synthesis
    Autorzy:
    Timko, M.
    Džarová, A.
    Kopčanský, P.
    Závišová, V.
    Koneracká, M.
    Kováč, J.
    Šprincová, A.
    Vaclavíková, M.
    Ivaničová, L.
    Vávra, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813922.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.75.+a
    47.65.Cb
    87.83.+a
    Opis:
    In this work, the magnetic properties of biologically produced magnetite (magnetosomes) by biomineralization process were compared to those of chemically synthesized $Fe_3O_4$. The coercivity of 185 Oe in magnetosomes is connected with the fact that the mean diameter is larger than critical size for transition from superparamagnetic to ferromagnetic behavior. A sharp magnetic transition at 105 K (Verwey transition) is clearly present in magnetosomes while in opposite, this transition is missing in $Fe_3O_4$.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 573-576
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of Magnetosomes After Exposure to the Effect of the Sonication and Ultracentrifugation
    Autorzy:
    Molčan, M.
    Hashim, A.
    Kováč, J.
    Rajňák, M.
    Kopčanský, P.
    Makowski, M.
    Gojzewski, H.
    Molokáč, M.
    Hvizdák, L.
    Timko, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368025.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.07.-b
    75.60.-d
    87.50.Y-
    68.37.-d
    Opis:
    Magnetosomes are intracellular organelles of widespread aquatic microorganisms called Magnetotactic bacteria. At present they are under investigation especially in biomedical applications. This ability depends on the presence of intracellular magnetosomes which are composed of two parts: first, nanometer-sized magnetite $(Fe_{3}O_{4})$ or greigite $(Fe_{3}S_{4})$ crystals (magnetosome crystal), depending on the bacterial species; and second, the bilayer membrane surrounding the crystal (magnetosome membrane). The magnetosomes were prepared by biomineralization process of magnetotactic bacteria Magnetospirillum Magnetotacticum sp. AMB-1. The isolated magnetosome chains (sample M) were centrifugated at speed of 100000 rpm for 4 hours (sample UM) and sonicated at power of 120 W for 3 hours (sample SM), respectively. The prepared suspensions were investigated with respect to morphological, structural and magnetic properties. The results from scanning electron microscopy showed that isolated chains of magnetosomes were partially broken to smaller ones after ultracentrifugation. On the other hand the application of the sonication process caused the formation of individual magnetosomes (unordered in chain). These results were confirmed by coercivity and magnetization saturation measurements.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 198-199
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Properties of Biocompatible Magnetic Fluid after Electron Irradiation
    Autorzy:
    Tomašovičová, N.
    Haysak, I.
    Koneracká, M.
    Kováč, J.
    Timko, M.
    Závišová, V.
    Okunev, A.
    Parlag, A.
    Fradkin, A.
    Sakhno, V.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429089.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.80.Fe
    61.82.Rx
    Opis:
    The magnetic particles in the water-based magnetic fluids were sterically stabilized by natrium oleate to prevent their agglomeration and consequently the adsorption of poly-ethylene-glycol (PEG) was carried out to improve the biocompatibility of the magnetic particles. Two sets of samples were prepared. The first set of the samples was with different molar weight of PEG (Mw = 400, 1000, 10000 and 20000) at the constant weight ratio of PEG/$Fe_3O_4$ = 0.25 and the second one was with different weight ratio of PEG/$Fe_3O_4$ and constant molar weight of PEG (Mw = 1000). The samples were irradiated with 20 Gy. The same reduction of saturated magnetization (about 10%) after electron irradiation with 20 Gy was observed for all prepared samples.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1302-1304
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Characterization of $Fe_3O_4$ Magnetic Nanoparticles Modified with Dextran and Investigation of Their Interaction with Protein Amyloid Aggregates
    Autorzy:
    Koneracká, M.
    Antošová, A.
    Závišová, V.
    Lancz, G.
    Gažová, Z.
    Šipošová, K.
    Juríková, A.
    Csach, K.
    Kováč, J.
    Tomašovičová, N.
    Fabián, M.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535048.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    87.14.em
    87.19.xr
    Opis:
    Functionalised magnetic nanoparticles composed of $Fe_3O_4$ particles stabilised by sodium oleate and subsequently modified with dextran (MFDEX) were prepared by the co-precipitation method. Their morphology and particle size distribution were observed by scanning electron microscopy and photon cross correlation spectroscopy. In order to confirm the modification of magnetite surface with dextran physical techniques, including infrared spectroscopy, thermal analysis, and magnetic measurement, were used. Finally, the effect of MFDEX on amyloid fibrillar aggregates of human insulin and hen egg white lysozyme, typical amyloidogenic proteins, was investigated. In vitro interaction of MFDEX with protein amyloid fibrils resulted into destruction of amyloid aggregates. The anti-amyloid activity makes MFDEX of potential interest as therapeutic agent against amyloid-related diseases.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 983-985
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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