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Wyświetlanie 1-15 z 81
Tytuł:
Effect of 1D Ordering on Magnetic Properties of Iron Nanoparticles coated by Silica Shell
Autorzy:
Zeleňáková, A.
Hrubovčák, P.
Zeleňák, V.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1030766.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.40.Cx
75.75.Fk
68.37.Og
Opis:
Peculiar magnetic properties of 1D arranged composite consisting of Fe nanoparticles coated by insulating SiO2 layer were studied. Silica layer promotes the self-organization of 4 nm iron nanoparticles to the chain-like structures. Magnetization study shows that prepared nanoparticles exhibit very strong inter-particle magnetic interactions, which lead to long-range ordering of nanoparticles magnetic moments. Magnetic properties show superferromagnetic behaviour. The low value of room temperature coercivity, the existence of electrical insulating silica layer and small size of iron nanoparticles favour studied material for potential usage in microelectronic devices designed for high voltage signals modulated by high frequencies.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 561-563
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reliability analysis of forest machines due to FMEA method
Autorzy:
Ťavoda, P.
Kováč, J.
Łukaszczyk, Z. Ł.
Powiązania:
https://bibliotekanauki.pl/articles/409738.pdf
Data publikacji:
2018
Wydawca:
STE GROUP
Tematy:
reliability
FMEA method
forest machines
maintenance
Opis:
The article deals with the research of operational reliability of forest felling machines with the method FMEA (Failure Mode and Effect Analysis) and its implementation for observed machines in the organization. Forwarders 810D by John Deere were chosen for this research. The research was realized in real operational conditions. Application of the FMEA method allows flexibility in case of unexpected situations and optimization of human potential abilities. FMEA tool is a tool preventing outages operational reliability and preventive tool for ensuring the maintenance of facilities. This paper explores and verifies the operational reliability theory in practical real-world conditions, resulting in a reduction in operating (variable) costs, minimization of failures and readiness and increased performance of observed machines.
Źródło:
Management Systems in Production Engineering; 2018, 4 (26); 200-206
2299-0461
Pojawia się w:
Management Systems in Production Engineering
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:
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:
Clean bulk YBaCuO superconductors doped by paramagnetic ions of Sm and Yb
Autorzy:
Jirsa, M.
Volochová, D.
Kováč, J.
Diko, P.
Powiązania:
https://bibliotekanauki.pl/articles/1054700.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Ha
74.25.Op
74.25.Sv
74.60.Ge
74.72.-h
Opis:
The recently developed clean cuprate technology was employed to study the effect of tiny amounts of paramagnetic Yb and Sm ions on electromagnetic properties of bulk YBaCuO. Small samples of about 1.5×1.5×0.5 mm³ were measured by vibrating sample magnetometer in the field range ±9 T and temperatures 30 K to 10 K in the non-superconducting tetragonal state and 300 K to 70 K in the orthorhombic, superconducting state. In the latter case, we observed the reversible paramagnetic moment above T_{C}, similar as in the tetragonal state. Below T_{C} an irreversible magnetic moment was observed from which critical current density, J_c, was evaluated using the extended Bean model. The effect of doping by Yb and Sm ions on J_c was studied and a correlation between J_c and the total paramagnetic moment was found. Both J_c(B) and the normalized pinning force density as a function of the reduced magnetic field were analyzed in terms of the classical model and discussed with respect to the material anisotropy, giving us at least a rough idea on the type of the effective pinning type and mechanism.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1027-1029
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Differentiation of Native and Reconstructed Ferritin using the MRI Gradient Echo Pulse Sequence
Autorzy:
Balejcikova, L.
Strbak, O.
Baciak, L.
Kovac, J.
Masarova, M.
Krafcik, A.
Kopcansky, P.
Dobrota, D.
Frollo, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032829.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Ej
83.85.Fg
87.61.-c
87.64.Cc
87.85.jf
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1093-1095
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elimination of Magnetic Nanoparticles with Various Surface Modifications from the Bloodstream in vivo
Autorzy:
Tomasovicova, N.
Khmara, I.
Koneracka, M.
Zavisova, V.
Kubovcikova, M.
Antal, I.
Kovac, J.
Muckova, M.
Kopcansky, P.
Powiązania:
https://bibliotekanauki.pl/articles/1032816.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Gg
75.50.Tt
87.85.jj
Opis:
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.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1159-1161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Co Doping on Induced Anisotropy and Domain Structure in Magnetic Field Annealed $(Fe_{1-x}Co_x)_{79}Mo_8Cu_1B_{12}$
Autorzy:
Kunca, B.
Marcin, J.
Švec, P.
Kováč, J.
Švec Sr., P.
Škorvánek, I.
Powiązania:
https://bibliotekanauki.pl/articles/1398273.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Tt
75.60.Ch
75.60.Nt
Opis:
The effect of heat treatment in applied magnetic field on the induced anisotropy and domain structure of $(Fe_{1-x}Co_x)_{79} Mo_8 Cu_1 B_{12}$ (x=0, 0.2, 0.5) nanocrystalline alloy system was investigated. A heat treatment of Co-doped samples under the application of longitudinal magnetic field resulted in squared hysteresis loops characterized by very low coercive field values. Sheared loops with tunable slope and good field linearity were obtained after annealing in transverse magnetic field. Corresponding domain structure showed uniform character, oriented in the direction parallel or perpendicular to the ribbon axis after longitudinal or transverse magnetic field annealing, respectively. No effect of magnetic field annealing was found in Co-free sample. Correlations between Co-doping, the Curie temperature, and soft magnetic properties after magnetic field annealing are discussed.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 759-761
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Mn doping on magnetic and structural properties of Co₂FeSi Heusler alloy
Autorzy:
Galdun, L.
Ryba, T.
Kováč, J.
Prida, V.
Hernando, B.
Vargová, Z.
Varga, R.
Powiązania:
https://bibliotekanauki.pl/articles/1054765.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
72.20.Lp
Opis:
We have studied the effect of Mn doping on structural and magnetic properties of Co₂FeSi Heusler alloy. Co₂FeSi, Co₂Mn_{0.25}Fe_{0.75}Si and Co₂Mn_{0.5}Fe_{0.5}Si alloys were prepared by melt spinning technique which offers fast and simple production of large amount of materials in a single production step. The rapid quenching method provides an opportunity to prepare Heusler alloys with highly ordered L2₁ structure confirmed by X-ray analysis in all the samples. Magnetic measurements revealed high Curie temperatures (>1000 K) and well defined easy magnetization plane parallel with the ribbon plane. Those attributes predispose given samples for applications in spintronics.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 866-868
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Pulse Heating on Rayleigh Area of Amorphous FINEMET-Type Alloy
Autorzy:
Novák, L.
Kováč, J.
Hubač, L.
Powiązania:
https://bibliotekanauki.pl/articles/1032143.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.50.Kj
75.60.Nt
75.60.Jk
Opis:
The effect of pulse annealing on magnetization processes in FINEMET-type alloy in weak magnetic fields (the Rayleigh area) is studied in this paper. Rapidly quenched FINEMET ribbon in the original amorphous state was chosen for the study. The significant differences in behavior of studied materials are ascribed to the differences in internal mechanical stresses, which bring about the changes in total magnetic anisotropy and consequently also changes in domain walls thickness.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 753-755
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of spark plasma sintering on microstructure and properties of bulk LaCaSrMnO magnetocaloric materials
Autorzy:
Zmorayová, K.
Antal, V.
Kováč, J.
Diko, P.
Noudem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1053176.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
61.72.-y
75.30.Kz
77.80.B-
81.70.Pg
81.20.Ev
81.30.Fb
Opis:
Polycrystalline La_{0.67}Ca_{0.33-x}Sr_xMnO₃ (x=0.33, 0.03, 0) (LCSM) perovskite samples treated by spark plasma sintering technique were investigated. This study proved influence of the sintering temperature on microstructure of these perovskite ceramics. The thermogravimetric measurements revealed the possibility of increase of oxygen content in studied LCSM samples by additional annealing under oxygen atmosphere and low temperature. Finally, the effect of this annealing on magnetic properties was demonstrated.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 804-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Thermal Processing in High Magnetic Field on Soft Magnetic Properties and Crystallographic Texture of Non-Oriented Fe-Si Steels
Autorzy:
Petryshynets, I.
Kováč, F.
Marcin, J.
Škorvánek, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032640.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Kj
61.72.-y
68.55.jm
75.60.Nt
75.50.Vv
Opis:
In this work, we report on the effects of high static magnetic field on the formation of desirable crystallographic orientation of grains ("rotating" cube) during the primary recrystallization of non-oriented steels. Vacuum degassed non-oriented steel with the silicon content about 1 wt% was taken from industrial line after final cold rolling with 80% of deformation and then it was subjected to the laboratory annealing at temperature of primary recrystallization. Whole annealing process was carried with and without the applied external magnetic field of 14 T. The analysis of crystallographic orientation of experimental material was studied by electron backscattered diffraction technique. The microstructural and textural observations have shown a small difference in average grain size between samples annealed with and without magnetic field as well as increase of the "rotating" Cube component and decrease of the intensity of deformation texture by application of magnetic field. The magnetic measurements show that the coercivity value of the sample annealed in the magnetic field of 14 T can be reduced by approximately 3% in comparison with sample annealed under the zero field conditions.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 783-785
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Miocene fluvial distributary system in the northern Danube Basin (Pannonian Basin System): depositional processes, stratigraphic architecture and controlling factors of the Piešťany Member (Volkovce Formation)
Autorzy:
Šujan, M.
Kováč, M.
Hók, J.
Braucher, R.
Rybár, S.
Leeuw, A. de
Powiązania:
https://bibliotekanauki.pl/articles/2060598.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
fluvial distributary system
facies analysis
sediment supply
accommodation
Pannonian Basin System
late Miocene
Opis:
Aim of the study was to investigate the detailed stratigraphic architecture of the alluvial Volkovce Formation, which was deposited in the northern Danube Basin during the interval between 10 and 6 Ma. Two type locality exposures were subject to facies analysis and interpretation of depositional processes and >500 boreholes served for correlation of spatial variability in the character of the formation. The study was focused on the northern Blatné and western Rišňovce depressions, which are partly separated by the Považský Inovec Mountains horst. It was revealed, that a mostly gravelly fluvial distributary system of the Piešťany Member was deposited in the northern Blatné depression, partly confined by the exposed horst and by incised palaeotopography. The sequence is composed of amalgamated braided river channel bodies with no overbank strata, in response to high sediment supply and low accommodation. The palaeo-stream then crossed the horst in its southern part towards the Rišňovce depression, where there was four times more accommodation. The submerged horst acted as a boundary, where the depositional processes changed to a meandering river and significant overbank deposits started to be preserved. Only small streams were present in the northern Rišňovce depression, which led to very low sediment supply compared to the high accommodation there. The depositional system was affected mainly by the incised palaeotopography, by the location of sediment input together with spatial differences in accommodation rate caused by the activity of the Ripňany Fault on the southeastern side of the Považský Inovec Mts.
Źródło:
Geological Quarterly; 2017, 61, 3; 521--548
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Structural Characterization of Nickel and Iron Based Heusler Ribbons Ni₂FeZ (Z = In, Sn, Sb)
Autorzy:
Frol'ová, L.
Ryba, T.
Vargová, Z.
Komanický, V.
Kováč, J.
Gyepes, R.
Varga, R.
Powiązania:
https://bibliotekanauki.pl/articles/1032228.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.30.Gw
Opis:
Comparison of structural, chemical, and magnetic properties of Ni₂FeZ (Z = In, Sn, Sb) Heusler ribbons produced by melt-spinning method is presented. The aim of work was to prepare the Heusler alloys with the appropriate chemical composition in a single step without additional thermal treatment. Scanning electron microscopy analysis revealed polycrystalline structure of all samples. It is shown that correct L2₁ structure of Ni₂FeSb can be obtained in a single production step. On the other hand, no Heusler L2₁ phase (nor its variants) occur in Ni₂FeSn alloy. Additionally, magnetic characterization revealed high Curie temperatures of the Heusler phases (above 600 K for Ni₂FeSb and 800 K for Ni₂FeIn).
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 735-737
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanochemical Preparation and Magnetic Properties of Fe₃O₄/ZnS Nanocomposite
Autorzy:
Bujňáková, Z.
Zorkovská, A.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032141.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
81.20.Ev
81.20.Wk
Opis:
Powder nanocomposite of Fe₃O₄/ZnS was prepared by mechanochemical synthesis in a planetary ball mill. In this reaction natural magnetite mineral Fe₃O₄ was used, together with zinc acetate (CH₃COO)₂Zn·2H₂O and sodium sulfide Na₂S·9H₂O, as precursors for the zinc sulfide ZnS. X-ray diffraction revealed that the sample is composed of small nanocrystalline particles, containing Fe₃O₄ and ZnS. The non-milled magnetite showed distinctive Verwey transition at around 120 K, this becomes suppressed after milling, as a consequence of structural disorder and presence of defects. Moreover, the reduction of saturation magnetization from 91 A m²/kg to 69.2 A m²/kg was observed, as a consequence of the milling process. The magnetization of the Fe₃O₄/ZnS nanocomposite was the lowest (34.5 A m²/kg), due to the milling and to the decreased weight fraction of the ferrimagnetic component. Nevertheless, the Fe₃O₄/ZnS sample demonstrates ferrimagnetic behavior as well, and its structure is less perturbed by milling, the Verwey transition, although less impressive, but is preserved.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1120-1122
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 81

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