Temat: 75.75.Fk - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Studies on Approximation Methods in Calculating the Magnetic Dipolar Interaction Energy, and Its Impact on the Relaxation Time of Magnetic Nanoparticle Systems
Autorzy:: Cacciola, M.
Berdie, A.
Tematy:: 75.75.Fk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1398670.pdf Link otwiera się w nowym oknie
Opis:: The studies on monodomain magnetic nanoparticle systems in colloidal suspensions have heightened lately due to their technological applications, in particular in medicine. Most applications depend on the behaviour of these systems in external magnetic field. In these systems, the nanoparticle dynamics are characterized by the Néel relaxation time and Brownian relaxation time. Due to the complexity of these systems, modelling and numerical simulation, requiring some methods of calculation, are used in the studies. Lately, it has been experimentally and theoretically shown that the magnetic dipolar interactions among nanoparticles influence the behaviour of the systems, even at low concentrations of nanoparticles. The complexity of the problem related to this type of interaction comes from its long-range anisotropic characteristic. This paper presents a series of studies on how the approximation methods, used for the dipolar magnetic interaction energy calculation, affect the magnetic nanoparticle relaxation time, as well as the impact of this aspect on the interpretation of results.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Manganese Perovskite Nanoparticles and the Downturn of Inverse Susceptibility above the Curie Temperature
Autorzy:: Maryško, M.
Pollert, E.
Kaman, O.
Veverka, P.
Jirák, Z.
Tematy:: 75.75.Fk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1533960.pdf Link otwiera się w nowym oknie
Opis:: In the $La_{0.75}Sr_{0.25}MnO_3$ nanoparticle system for hyperthermia a downturn in the inverse susceptibility above the Curie temperature $T_{c}$ was observed and interpreted in terms of a finite width of the $T_{c}$ distribution.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Magnetic Properties of Fe@Pt Nanoparticles with Core/Shell Morphology
Autorzy:: Zeleňáková, A.
Zeleňák, V.
Bednarčík, J.
Lauda, M.
Kováč, J.
Tematy:: 75.75.Fk
75.50.Vv
75.40.Gb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1535141.pdf Link otwiera się w nowym oknie
Opis:: We have investigated the magnetic properties of iron nanoparticles coated by platinum shell prepared by chemical procedure. Magnetic measurements using SQUID magnetometer confirm the behaviour typical for a superparamagnetic system. From the M(H) loop at 300 K the magnetic moment of each particle $m_{P}$ ≈ $250 μ_{B}$ was calculated. The magnetic relaxation study by the in-phase χ' and out-of-phase χ" ac susceptibilities in frequency range 0.1-1000 Hz suggests the existence of two magnetic layers with different magnetic spin's dynamics and strong dipolar interactions between nanoparticles. The observed magnetic behaviour is caused by the blocking process of interacting superparamagnetic particles with magnetic iron core, diamagnetic platinum shell and spin-glass like behaviour magnetic interlayer between them.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Vortex State Suppression in a Hexagonal Array of Interacting Py Triangular Rings
Autorzy:: Spizzo, F.
Patrignani, L.
Bisero, D.
Vavassori, P.
Metlushko, V.
Tematy:: 75.60.Jk
75.75.Fk
75.30.Gw; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399696.pdf Link otwiera się w nowym oknie
Opis:: We investigate the effect of magnetostatic interactions on the magnetization reversal process of equilateral triangular rings arranged on a hexagonal lattice. Inter-ring interactions originate as rings corners host domain-walls that produce an intense dipolar field; the effect of such interactions is studied by recording hysteresis loops for different magnetic field orientations. Rings magnetic configuration is probed via magnetic force microscopy and diffraction magneto-optic Kerr effect measurements. We observe that the effect of stray fields due to domain-walls competes with that of shape anisotropy, and that the former prevails when the magnetic field orientation is parallel to rings symmetry axes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Magnetometric Measurements of Low Concentration of Coated $Fe_{3}O_{4}$ Nanoparticles
Autorzy:: Škrátek, M.
Šimáček, I.
Dvurečenskij, A.
Majerová, M.
Maňka, J.
Tematy:: 85.25.Dq
75.50.Bb
75.75.Fk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1372486.pdf Link otwiera się w nowym oknie
Opis:: A modified RF SQUID system with the $2^{nd}$ order gradiometer has been tested for the purposes of detecting the magnetic nanoparticles as potential carriers of biological medicament. The paper presents basic information about the sensitivity of the system and its use for quantification of low concentration of coated $Fe_{3}O_{4}$ magnetic nanoparticles. Model measurements provided information that enabled us to define the parameter influencing the experimental results. The volume of the biological object and its distance from the antenna appear to have the significant influence on the measurement accuracy.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Ordered Nanoporous Silica Modified with Nanoparticles of Lanthanide Oxides
Autorzy:: Zeleňáková, A.
Kapusta, O.
Zeleňák, V.
Tematy:: 75.75.Fk
81.05.Rm
75.40.Cx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1368473.pdf Link otwiera się w nowym oknie
Opis:: Lanthanide oxide nanoparticles were encapsulated inside of pores of highly ordered periodic silica of SBA15 type with hexagonal symmetry. The magnetic properties of such nanoperticles were investigated. The structural characterization using the SAXS, XANES, XRD, and $N_{2}$ adsorption measurements showed the presence of lanthanide oxides of $Ln_{2}O_{3}$ type (Ln=La, Pr, Nd, Gd, Eu), with the size of about 5 nm, incorporated in nanoporous channel system. Their magnetic properties, studied by SQUID apparatus, showed the weak antiferromagnetic ordering at 2 K in the nanocomposites $Gd_{2}O_{3}$@SBA15, $Pr_{2}O_{3}$@SBA15 and $Nd_{2}O_{3}$@SBA15. This behaviour of the nanoparticles is caused by blocking process of magnetic moments, which at 300 K exhibit the superparamagnetism, evidenced from ZFC/FC magnetization.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 7.

Tytuł:: AC Magnetic Susceptibility Study of Fe and Co Based Nanoparticles
Autorzy:: Zeleňáková, A.
Kováč, J.
Zeleňák, V.
Tematy:: 75.75.Fk
81.05.Rm
75.40.Cx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1368479.pdf Link otwiera się w nowym oknie
Opis:: We have investigated magnetic properties of three different samples composed of magnetic Fe or Co core and protective Au or Pt metallic shell, namely Fe@Au, Co@Au and Fe@Pt samples, with sizes of about 10 nm, 8 nm and 5 nm respectively. We have measured and analysed the experimental data of real and imaginary component of ac susceptibility through theoretical laws for non-interacting and interacting particles and we have estimated the strength of their magnetic interactions. Our analyses showed the increase of inter-particle interactions with decreasing particles size.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Structure and Magnetic Properties of Three-Dimensional Gadolinium-Based Hybrid Framework
Autorzy:: Almáši, M.
Zeleňáková, A.
Císařová, I.
Bednarčík, J.
Zeleňák, V.
Tematy:: 75.75.Fk
81.05.Rm
75.40.Cx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1371241.pdf Link otwiera się w nowym oknie
Opis:: In the present work we have focused on the preparation and magnetic study of coordination polymer formed by Gd(III) cations as nodes and formate (HCOO¯; FOR) anions as charge compensating linkers. The prepared complex with formula ${[Gd(μ_{3}-FOR)_{3}]}_{n}$ was characterized by single-crystal X-ray diffraction, and high-energy powder X-ray diffraction. The structural study showed that complex is formed by 3D polymeric network with the shortest Gd-Gd, distances of 3.998 Å. The magnetic properties of the complex were studied by magnetic susceptibility $χ_{M}(T)$ and magnetization M(H) measurements. The results show on the weak antiferromagnetic coupling at low temperatures represented by the Weiss constant θ=-0.468 K. The value of effective magnetic moment $μ_{eff}=7.57μ_{B}$, which was estimated from the experimental data is close to the theoretical value for systems with S=7/2. Correlation between crystal structure of complexes and magnetic properties is presented.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 9.

Tytuł:: Effect of BSA Protein on the Contrast Properties of Magnetite Nanoparticles during MRI
Autorzy:: Strbak, O.
Kubovcikova, M.
Baciak, L.
Khmara, I.
Gogola, D.
Koneracka, M.
Zavisova, V.
Antal, I.
Masarova, M.
Krafcik, A.
Kopcansky, P.
Dobrota, D.
Frollo, I.
Tematy:: 87.61.-c
75.75.Fk
87.15.kp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1032224.pdf Link otwiera się w nowym oknie
Opis:: The aim of the study was to establish whether there is a significant change in the MRI contrast of magnetite nanoparticles, after BSA protein binding on the surface of particles. The rationale is the applicability of this feature in clinical practice for the tracking of specific proteins which are often associated with various pathologies. Contrast agents could bind to this specific marker, with the change in MRI contrast indicating the presence of pathology. We found that changes in relative contrast acquired at low-field MRI offer potential for the differentiation of magnetite nanoparticles with and without BSA protein. However, the variations in the transverse relaxation time (T₂) and transverse relaxivity (r₂), acquired at high-field MRI, were too small to be applicable for biomedical applications.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Effect of 1D Ordering on Magnetic Properties of Iron Nanoparticles coated by Silica Shell
Autorzy:: Zeleňáková, A.
Hrubovčák, P.
Zeleňák, V.
Kováč, J.
Tematy:: 75.40.Cx
75.75.Fk
68.37.Og; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030766.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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