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Wyszukujesz frazę "Molcan, M." wg kryterium: Autor


Wyświetlanie 1-7 z 7
Tytuł:
The Effect of Sonication on Acoustic Properties of Biogenic Ferroparticle Suspension
Autorzy:
Józefczak, A.
Hornowski, T.
Król, A.
Molčan, M.
Leszczyński, B.
Timko, M.
Powiązania:
https://bibliotekanauki.pl/articles/176978.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnetosomes
sonication
ultrasonic properties
Opis:
Superparamagnetic iron oxide nanoparticles (SPION) synthesised chemically usually need the modification of the particle surface. Other natural sources of magnetic particles are various magnetotactic bacteria. Magnetosomes isolated from magnetotactic bacteria are organelles consisting of magnetite (Fe3O4) or greigite (Fe3S4) crystals enclosed by a biological membrane. Magnetotactic bacteria produce their magnetic particles in chains. The process of isolation of magnetosome chains from the body of bacteria consists of a series of cycles of centrifugation and magnetic decantation. Using a high-energy ultrasound it is possible to break the magnetosome chains into individual nanoparticles – magnetosomes. This study presents the effect of sonication of magnetosome suspension on their acoustic properties, that is speed and attenuation of the sound. Acoustic propagation parameters are measured using ultrasonic spectroscopy based on FFT spectral analysis of the received pulses. The speed and attenuation of ultrasonic waves in magnetosome suspensions are analysed as a function of frequency, temperature, magnetic field intensity, and the angle between the direction of the wave and the direction of the field.
Źródło:
Archives of Acoustics; 2016, 41, 1; 161-168
0137-5075
Pojawia się w:
Archives of Acoustics
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:
Influence of Magnetic Field on Dielectric Breakdown in Transformer Oil Based Ferrofluids
Autorzy:
Rajňák, M.
Dolník, B.
Marton, K.
Tomčo, L.
Molčan, M.
Kopčanský, P.
Timko, M.
Kurimský, J.
Powiązania:
https://bibliotekanauki.pl/articles/1201920.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
77.22.Jp
75.75.Jn
Opis:
In this paper the experimental study of the breakdown field strength in a transformer oil based ferrofluid is reported. The experiments are conducted on five ferrofluid samples with different magnetic volume fraction. The influence of external magnetic field on the breakdown field strength is investigated, when a quasi-homogenous magnetic field was applied in parallel and perpendicular configuration in regard to the electric field. The obtained results are analysed in accordance to the electron charging of ferrofluid nanoparticles theory.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 248-249
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Properties of Magnetosome Suspension under the Influence of Magnetic Field
Autorzy:
Józefczak, A.
Molčan, M.
Rozynek, Z.
Hornowski, T.
Skumiel, A.
Timko, M.
Tóthová, J.
Kopčanský, P.
Leszczyński, B.
Powiązania:
https://bibliotekanauki.pl/articles/1387965.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
43.35.Bf
Opis:
The magnetotactic bacteria synthesize chains of nanosized magnetic particles that function as a compass needle to navigate in the direction of the earth's magnetic field. Magnetosomes are bacterial magnetic nanoparticles containing iron mineral crystals of magnetite or greigite, enveloped by a natural biological membrane. The objective of the work is to study the influence of magnetic field on rheology and acoustic properties of magnetosome suspension. Experimental results show a clear effect of the external magnetic field on the acoustic parameters such as velocity and attenuation of ultrasonic wave, and the viscosity of the suspension, arising from the biogenic magnetic particles aggregation.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 629-631
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Morphology on Magnetic Properties of Magnetosomes
Autorzy:
Hashim, A.
Molčan, M.
Kovač, J.
Varchulová, Z.
Gojzewski, H.
Makowski, M.
Kopčansky, P.
Tomori, Z.
Timko, M.
Powiązania:
https://bibliotekanauki.pl/articles/1428653.pdf
Data publikacji:
2012-05
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
Opis:
Cultivation process was changed three times. The culture medium was enriched by more amount ferric quinate (FQ magnetosomes sample) and more amounts Wolfe's vitamin solution (WVS magnetosomes sample) comparing to normal culture medium (NP magnetosomes sample). NP sample of magnetosomes shows zero coercivity and behaves superparamagnetically. The increase of coercivity (6.5 Oe for WVS and 20 Oe for FQ) may be caused by higher value of shape anisotropy and reveals stronger magnetic correlations between particles of magnetite chains.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1250-1252
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:
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.
Powiązania:
https://bibliotekanauki.pl/articles/1428655.pdf
Data publikacji:
2012-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
47.65.Cb
77.22.Gm
77.22.Ch
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.
Źródło:
Acta Physica Polonica A; 2012, 121, 5-6; 1253-1256
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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