Temat: 47.65.Cb - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Thermogravimetric Study of the Decomposition of BSA-Coated Magnetic Nanoparticles
Autorzy:: Csach, K.
Juríková, A.
Miškuf, J.
Koneracká, M.
Závišová, V.
Kubovčíková, M.
Kopčanský, P.
Tematy:: 47.65.Cb
65.80.-g; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1429064.pdf Link otwiera się w nowym oknie
Opis:: Magnetic nanoparticles used in biomedicine have to be biocompatible, which can be achieved by the modification of the magnetic particle surface with an appropriate biocompatible substance. In the work protein bovine serum albumin (BSA) was chosen to modify the surface of magnetic nanoparticles. The BSA-coated magnetic nanoparticles with different input weight ratios of BSA to the magnetite $Fe_3O_4$ were prepared and thermally characterized using thermogravimetric and differential scanning calorimetric analysis. The adsorption of BSA on the magnetic nanoparticles in wide range of concentration was confirmed. The activation energies of the thermal decomposition of the complex system were estimated.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Thermal Analysis of Magnetic Nanoparticles Modified with Dextran
Autorzy:: Juríková, A.
Csach, K.
Miškuf, J.
Koneracká, M.
Závišová, V.
Kubovčíková, M.
Kopčanský, P.
Tematy:: 47.65.Cb
65.80.-g; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1429065.pdf Link otwiera się w nowym oknie
Opis:: In the work the thermal behaviour of the magnetic nanoparticles modified with polysaccharide dextran of different weight ratios to the magnetite $Fe_3O_4$ was investigated using thermoanalytical methods - differential scanning calorimetry and thermogravimetric analysis. The adsorption of dextran on the magnetic nanoparticles was confirmed and the influence of the dextran amount in the modified magnetic fluid on the thermal decomposition of the complex system was studied. The results showed that magnetite catalyzed the thermal decomposition of dextran, the adsorbed dextran showed lower initial decomposition temperatures in comparison with the free one.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Variation of magnetic fluid deformation related to nanoparticle concentration in steady electric field
Autorzy:: Kosterec, M.
Kurimský, J.
Cimbala, R.
Špes, M.
Farkaš, R.
Dolník, B.
Gamcová, M.
Rajňák, M.
Timko, M.
Kopčanský, P.
Paulovičová, K.
Vargová, B.
Tematy:: 47.65.Cb
41.20.-q
47.55.D-; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1048186.pdf Link otwiera się w nowym oknie
Opis:: Today, it is important to know the behaviour of magnetic fluids applied in the power electrical machines, e.g. in power transformers, when exposed to an electric field. Besides their promising applications in high voltage engineering, they are of increasing interest from designed assembly and pattern formation point of view. The structure of such magnetic fluids is easily controllable by external magnetic fields. However, less attention has been paid to structural phenomena in magnetic fluids induced by electric fields. The core of this paper is dedicated to the experimental observation of a magnetic fluid droplet deformation in a steady electric field. The mutual relation between the deformation parameter and magnetic nanoparticles concentration is analysed. Spatio-temporal analysis of the droplet shape is presented in the paper. The phenomena of the droplet deformation were recorded by a camera. The detailed experimental procedure is presented. The method of deformation parameter calculation based on the linear pixel as the smallest-size unit in digital image is written. Finally, the relation between the deformation parameter and the nanoparticle volume concentration, as well as the time and magnitude of the DC field application are thoroughly evaluated. The results show that the deformation parameter decreases with increasing concentration at constant applied steady electric field but increases with increasing applied steady electric field.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Measurement of Complex Permittivity of Oil-Based Ferrofluid in Magnetic Field
Autorzy:: Kúdelčík, J.
Hardoň, Š.
Varačka, L.
Tematy:: 47.65.Cb
77.22.Gm
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030262.pdf Link otwiera się w nowym oknie
Opis:: The changes of dielectric parameters in oil-based ferrofluid have been measured in an external magnetic field. The frequency dependent real permittivity and the dissipation factor were measured within the frequency ranges from 1 mHz to 2 MHz by a capacitance method. These parameters have been studied in combined electric and magnetic field, when fields were parallel and perpendicular. The Cole-Cole model has been used to analyze measured data. When a magnetic field was applied, the interaction between the magnetic field and magnetic moments of nanoparticles led to the aggregation of magnetic nanoparticles to new structures - thick chains which had influence on the value of dielectric permittivity. At constant magnetic field the dependence of real permittivity and tanδ on angle between the electric and magnetic field (anisotropy) were measured, too. The various influences of magnetic field development on the investigated liquid are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The Investigation on the E-J Characteristics and the Role of Nanoparticle Concentration in Weakly Polar Magnetic Fluids
Autorzy:: Kurimský, J.
Dolník, B.
Marton, K.
Kolcun, M.
Tomčo, L.
Rajňák, M.
Timko, M.
Kopčanský, P.
Tematy:: 47.65.Cb
77.22.Jp
84.37.+q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1201885.pdf Link otwiera się w nowym oknie
Opis:: The paper presents investigation on the magnetic fluids that are stable colloidal suspensions of single-domain magnetic particles in a liquid carrier of dielectrics nature. Studies were made on the electric field vs. current density, e.i. E-J characterization commonly observed in insulating liquids under uniform low electric or magnetic fields. High performance oil was used as the dielectric carrier. The experiments were carried out at different volume concentrations of magnetite nanoparticles up to 4%.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Magnetodielectric Properties of Transformer Oil Based Magnetic Fluids
Autorzy:: Timko, M.
Kopcansky, P.
Molcan, M.
Tomco, L.
Marton, K.
Molokac, S.
Rybar, P.
Stoian, F.
Holotescu, S.
Taculescu, A.
Tematy:: 47.65.Cb
77.22.Gm
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1428655.pdf Link otwiera się w nowym oknie
Opis:: This contribution is devoted to study of dielectric and magnetodielectric properties in transformer oil based magnetic fluid. The dielectric permittivity and their anisotropy at various mutual orientation electric (50 Hz) and magnetic field were shown at the different volume concentrations of nanoparticles at room temperature. The linear increase of dielectric constant with volume concentration was confirmed which is in good agreement with the theoretical Maxwell prediction. The dielectric anisotropy factor g(B, ω) is very close to g=1. The values of permittivity increased with the increase of volume fraction of magnetite nanoparticles. The highest value of anisotropy characterized by deviation of permittivity $Δε=ε_{∥} - ε_{⊥}$ was found for the highest volume concentration which could mean that no aggregation of magnetite nanoparticles had appeared.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Influence of Electric Field on AC Magnetic Susceptibility of a Mineral Oil Based Ferrofluid
Autorzy:: Rajňák, M.
Dolník, B.
Tobiáš, T.
Paulovičová, K.
Kurimský, J.
Cimbala, R.
Kopčanský, P.
Timko, M.
Tematy:: 47.65.Cb
75.30.Cr
47.65.-d; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030753.pdf Link otwiera się w nowym oknie
Opis:: In a ferrofluid, the magnetic susceptibility at low magnetic fields is sensitive to the size and shape of magnetic nanoparticles and their concentration in a liquid carrier. In this paper we report on the AC magnetic susceptibility of a ferrofluid based on a mineral oil and iron oxide nanoparticles coated with oleic acid. As this type of ferrofluid is of increasing interest for electrical engineering applications, we investigate the effect of an external electric field and an electric current flowing through the ferrofluid on the AC magnetic susceptibility at ambient conditions. It is known that the action of the electric field on the oil based ferrofluids can result in the particle assembling. Then, the induced structural changes may affect the magnetic susceptibility of the bulk ferrofluid. In our experimental study we observed that the ferrofluid magnetic susceptibility decreases with increasing electric field. However, a heating effect with increasing electric field was observed too. Hence, it is concluded that besides the structural changes, the Joule heating has an obvious impact on the magnetic susceptibility of the ferrofluid in the external electric field.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Thermal Analysis of Magnetic Polymer Nanospheres for Drug Targeting
Autorzy:: Juríková, A.
Csach, K.
Miškuf, J.
Koneracká, M.
Závišová, V.
Kopčanský, P.
Tematy:: 47.65.Cb
65.80.-g
47.63.mh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1535061.pdf Link otwiera się w nowym oknie
Opis:: Poly(D,L-lactic-co-glycolic) acid (PLGA) polymer nanospheres loaded with different input amounts of anticancer drug taxol were prepared by the modified nanoprecipitation method. Magnetite was incorporated into the polymer nanospheres to impart them superparamagnetic properties. Thermal properties of the drug loaded magnetic polymer nanospheres were characterized using differential scanning calorimetry and thermogravimetric analysis. The solid state solubility of taxol in PLGA nanospheres and the influence of external magnetic field on their thermal stability were estimated. The investigations have revealed that the samples of dried taxol loaded magnetic PLGA nanospheres undergo mass loss at three stages during heating.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

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.
Tematy:: 47.65.Cb
85.70.-w
75.30.Cr
75.47.Lx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1429127.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Influence of Temperature on the Magneto-Dielectrics Effect of Oil-Based Ferrofluid
Autorzy:: Kúdelčík, J.
Hardoň, Š.
Bury, P.
Timko, M.
Kopčanský, P.
Tematy:: 47.65.Cb
77.22.Gm
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030417.pdf Link otwiera się w nowym oknie
Opis:: The effect of temperature on the magneto-dielectrics behavior was studied by dielectric spectroscopy in the transformer oil-based ferrofluid with magnetic nanoparticles upon the effect of an external magnetic field. The frequency dependence of complex permittivity and dissipation factor were measured within the frequency range from 1 mHz to 10 kHz at different temperatures by a capacitance method. The dielectrics parameters were measured as a function of the external magnetic field in the range of 0-200 mT, parallel to the direction of the electric field as a function of temperature in the range of 15-35°C. The interaction between magnetic field and magnetic moments of nanoparticles led to the aggregation of magnetic nanoparticles to new structures which had influence on dielectric parameters. The dependence of these parameters at constant magnetic field on angle between the direction of the electric and magnetic fields (anisotropy) has been measured, too.
Dostawca treści:: Biblioteka Nauki

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