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1

[FeCl_{4}]¯ Ionic Liquid Based Ferrofluids

100%

Parnica J., Kesa P., Kovac J., Timko M., Antalik M.

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vol. 126

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issue 1

276-277

EN

Magnetic ionic liquids derived from hydrochloride methyl ester alanine amino acids (AA) and FeCl_{3} were synthesized in ethanol and their magnetic properties were investigated. Iron (III) chloride forms ionic liquid in ethanol at saturated concentrations by the transfer of Cl¯ anion from one molecule of FeCl_{3} to the other molecule with the creation of tetrachloro ferrate anion [FeCl_{4}]¯ as well as dimer [Fe_{2}Cl_{7}]¯. Raman scattering indicates that after addition of hydrochloride methyl ester alanine to ethanol solutions of FeCl_{3} increase the intensities of signal at the frequencies at 318 cm^{-1} and 380 cm^{-1} as markers for the presence of [FeCl_{4}]¯ and [Fe_{2}Cl_{7}]¯ complexes. The magnetization at room temperature showed in both samples a linear dependence on the applied magnetic field. On the other hand, in the Raman scattering experiments the magnetization is smaller for FeCl_{3} sample in the presence of methyl ester alanine.

2

Structure and Transport Properties of La_{0.75-x}RE_xCa_{0.25}MnO_3 (RE = Gd, Dy, Ho; 0≤ x≤0.75) Manganites

86%

Drozd V., Pękała M., Kovac J., Skorvanek I., Szymański M., Nedilko S.

Acta Physica Polonica A

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2004

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vol. 106

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issue 5

751-758

EN

Structure and transport properties have been studied for a series of La_{0.75-x}RE_xCa_{0.25}MnO_3 manganites with heavy rare earth ions of Gd, Dy, Ho substituting La with x=0, 0.10, 0.25, 0.50, and 0.75. Polycrystalline samples were prepared by the carbonate precipitation route. The oxygen content was determined by the iodometric titration. The X-ray investigations carried out by the powder method show that the unit cell volume gradually decreases and orthorhombic distortion of the lattice increases with rising RE content. Below the room temperature the electrical resistivity is of the semiconducting type for all the samples studied. Electrical resistivity vs. temperature dependences were analyzed within different models: simple thermal activation, Mott's variable range hopping, adiabatic, nonadiabatic, and bipolaron. The Curie temperatures of Gd, Dy, and Ho substituted manganites determined from magnetization measurements show that at 280 K all the samples are in the paramagnetic phase. The increasing RE fraction reduces magnetization at 4 K as compared to La_{0.75}Ca_{0.25}MnO_3.

3

Influence of Zn on Structure and Magnetic Properties of Rapid Quenched (Fe-Zn)-Cu-Nb-Si-B Alloys

86%

Kolesar V., Michalik S., Kovac J., Girman V., Sovak P., Kollar P.

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issue 5

790-791

EN

The aim of this work was to study the influence of Zn on the formation of nanostructure in Fe_{73.5 - x}Zn_xCu_1Nb_3Si_{13.5}B_9 (x = 1, 3, 5) ribbons prepared by the melt-spinning technique. X-ray diffraction measurements proved amorphous state of the sample with x = 1. The sample with x = 3 contains a small fraction of Fe_3Si phase and the sample with x = 5 is in nanocrystalline state with the average grain size of about 25 nm. The reduced radial distribution function G(r) was calculated for local structure investigation. Increasing Zn content enhances crystallization during solidification which leads to increase of magnetocrystalline anisotropy and consequently to increase of coercivity.

4

Preparation and Investigations of Ni_{0.2}Zn_{0.8}Fe₂O₄ Ferrite Nanofiber Membranes by Needleless Electrospinning Method

86%

Streckova M., Mudra E., Sebek M., Sopcak T., Dusza J., Kovac J.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

729-731

EN

The preparation of Ni_{0.2}Zn_{0.8}Fe₂O₄ nanofiber membranes by simple and versatile needleless electrospinning technique is presented. The single phase of spinel ferrite membrane was obtained after conventional thermal treatment of polyvinyl alcohol (PVA)/metal nitrate precursors at 800°C for 4 h in air. The formation of single-phase fibers was characterized using differential scanning calorimetry accompanied with thermogravimetric analysis. The surface morphology, microstructure and crystal structure were investigated by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The magnetic properties of the fibrous samples measured in the temperature range from 2 to 300 K verify a soft magnetic behavior, which is quite typical for ferrimagnetic spinel-type ferrites.

5

Elimination of Magnetic Nanoparticles with Various Surface Modifications from the Bloodstream in vivo

73%

Tomasovicova N., Khmara I., Koneracka M., Zavisova V., Kubovcikova M., Antal I., Kovac J., Muckova M., Kopcansky P.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

1159-1161

EN

The magnetic nanoparticles with the core diameter 10 nm stabilized by sodium oleate and bovine serum albumin in phosphate buffer have been modified by different biocompatible substances such as poly(ethylene glycol) (PEG), dextran (DEX), and polyvinylpyrrolidone (PVP). Prepared biocompatible magnetic fluids were characterized to obtain the particle size distribution using scanning electron microscopy and the dynamic light scattering method. To study the elimination of different modified magnetic nanoparticles from bloodstream, the biocompatible samples were applied intravenously to the mice bloodstream with further blood specimens collecting in given time intervals. Magnetic moment of the lyophilized blood samples was measured by SQUID magnetometer. Time dependence of magnetic moment of magnetic nanoparticles and magnetic nanoparticles modified by DEX, PEG and PVP normalized to the Fe₃O₄ showed that the circulation time of magnetic nanoparticles in the bloodstream depends on the substance used for modification. The unmodified magnetic nanoparticles were trapped by reticuloendothelial system within 1 h while magnetic nanoparticles modified by DEX, PEG and PVP circulated in blood up to 3 h.

6

Differentiation of Native and Reconstructed Ferritin using the MRI Gradient Echo Pulse Sequence

73%

Balejcikova L., Strbak O., Baciak L., Kovac J., Masarova M., Krafcik A., Kopcansky P., Dobrota D., Frollo I.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

1093-1095

EN

Ferritin is a biological iron storage biomacromolecule, consisting of a spherical protein shell (apoferritin) and mineral iron core. It plays a crucial role in the pathological processes of disrupted iron homeostasis followed by iron accumulation, linked with various disorders (e.g. neuroinflammation, neurodegeneration, cirrhosis, cancer, etc.) In vitro reconstructed ferritin, with the assistance of a non-invasive magnetic resonance imaging technique, has the potential to become a suitable biomarker of these pathological processes. Through gradient echo pulse sequencing, we were able to clearly distinguish between native (physiological) and reconstructed/iron-overloaded (pathological) ferritin, which can serve as a starting point for the development of a method for their differentiation. Such method is necessary for the early diagnosis of iron-based diseases.

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[FeCl_{4}]¯ Ionic Liquid Based Ferrofluids

Structure and Transport Properties of La_{0.75-x}RE_xCa_{0.25}MnO_3 (RE = Gd, Dy, Ho; 0≤ x≤0.75) Manganites

Influence of Zn on Structure and Magnetic Properties of Rapid Quenched (Fe-Zn)-Cu-Nb-Si-B Alloys

Preparation and Investigations of Ni_{0.2}Zn_{0.8}Fe₂O₄ Ferrite Nanofiber Membranes by Needleless Electrospinning Method

Elimination of Magnetic Nanoparticles with Various Surface Modifications from the Bloodstream in vivo

Differentiation of Native and Reconstructed Ferritin using the MRI Gradient Echo Pulse Sequence