scholarly journals Magnetization Reversal and Specific Loss Power of Magnetic Nanoparticles in Cellular Environment Evaluated by AC Hysteresis Measurement

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Satoshi Ota ◽  
Tsutomu Yamada ◽  
Yasushi Takemura
Keyword(s):  
Magnetic Nanoparticles ◽  
Theoretical Model ◽  
Single Cell ◽  
Magnetization Reversal ◽  
Heat Dissipation ◽  
Magnetic Moments ◽  
Hysteresis Loops ◽  
Dipole Interactions ◽  
Fixed Sample ◽  
Cellular Environment

The effect of intracellular hyperthermia induced by magnetic nanoparticles (MNPs) has been evaluated using a theoretical model. In this study, magnetization reversal of MNPs in the cellular environment under an AC magnetic field was evaluated on the basis of measured AC hysteresis loops. The specific and intrinsic loss powers—SLP and ILP—were also estimated from the area of AC hysteresis loops. The measured samples were a liquid sample dispersed in water, a fixed sample mixed with an epoxy bond, and a cellular sample. In the cellular environment, the rotations of particles and magnetic moments were inhibited by particle-cell and dipole-dipole interactions, respectively. The heat dissipation of the MNPs in the cellular environment was lower than that of the liquid and fixed samples. Moreover, the SLP in a single cell was estimated. The temperature increase of a single cell was calculated on the basis of the conventional theoretical model and the SLP measured in a single cell.

scholarly journals Recent Advances in Understanding Magnetic Nanoparticles in AC Magnetic Fields and Optimal Design for Targeted Hyperthermia

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Hiroaki Mamiya
Keyword(s):  
Magnetic Nanoparticles ◽  
Optimal Design ◽  
Magnetic Fields ◽  
Heat Dissipation ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Future Prospects ◽  
Hyperthermia Treatment ◽  
Selective Heating ◽  
Magnetic Hysteresis Loops

Targeted hyperthermia treatment using magnetic nanoparticles is a promising cancer therapy that enables selective heating of hidden microcancer tissues. In this review, I outline the present status of chemical synthesis of such magnetic nanoparticles. Then, the latest progress in understanding their heat dissipation mechanisms under large magnetic fields is overviewed. This review covers the recently predicted novel phenomena: magnetic hysteresis loops of superparamagnetic states and steady orientations of easy axes at the directions parallel, perpendicular, or oblique to the AC magnetic field. Finally, this review ends with future prospects from the viewpoint of optimal design for efficacy with a low side-effect profile.

scholarly journals Hydrothermal Novel Synthesis of Neck-structured Hyperthermia-suitable Magnetic (Fe3O4, γ-Fe2O3 and α-Fe2O3) Nanoparticles

2011 ◽  
Vol 4 (1) ◽  
pp. 99 ◽  
Author(s):  
M. S. Islam ◽  
J. Kurawaki ◽  
Y. Kusumoto ◽  
M. Abdulla-Al-Mamun ◽  
M. Z. Bin Mukhlish
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Magnetic Nanoparticles ◽  
Quantum Interference ◽  
Heat Dissipation ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Particle Morphology ◽  
Ferrous Chloride ◽  
Size And Morphology

Novel neck-structured Fe3O4, γ-Fe2O3 and α-Fe2O3 magnetic nanoparticles were successfully prepared by a modified hydrothermal method. Ferrous chloride tetrahydrate was solely used as a precursor for the novel nanomaterials. The X-ray diffractometric study revealed the purity of the nanomaterials thus synthesized. All of the products were characterized using a field-emission scanning electron microscope (FE-SEM) and a transmission electron microscope (TEM) for the particle size and morphology. Neck-structured particle morphology was observed for the first time in all of iron oxides with magnetic properties. The particle size observed was 50–60 nm. The synthesized nanomaterials showed excellent magnetization values when magnetic hysteresis loops were measured using a superconducting quantum interference device (SQUID). Moreover, the as-prepared magnetic nanoparticles suspensions showed significant temperature increments under an AC (alternating current) magnetic-field induction condition at room temperature which indicates the hyperthermia feasibility. Keywords: Magnetic materials; Neck-structured; Hyperthermia; Heat dissipation. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i1.8727J. Sci. Res. 4 (1), 99-107 (2012)

scholarly journals Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Devika Sudsom ◽  
Andrea Ehrmann
Keyword(s):  
Magnetic Materials ◽  
Data Storage ◽  
Magnetization Reversal ◽  
Hysteresis Loops ◽  
Object Oriented ◽  
Basic Research ◽  
Memory Systems ◽  
The Other ◽  
Micromagnetic Simulations ◽  
Nanodot Arrays

Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing.

scholarly journals Asymmetric Magnetization Reversal in Exchange-Biased Hysteresis Loops

2000 ◽  
Vol 84 (17) ◽  
pp. 3986-3989 ◽  
Author(s):  
M. R. Fitzsimmons ◽  
P. Yashar ◽  
C. Leighton ◽  
Ivan K. Schuller ◽  
J. Nogués ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Hysteresis Loops

Investigation on the Origin of Magnetization in Plastically Deformed NI51TI49 Alloy

2017 ◽  
Vol 743 ◽  
pp. 13-18
Author(s):  
Anna Drozdova ◽  
Alexander Nyavro ◽  
Lyudmila Kveglis
Keyword(s):  
Crystal Lattice ◽  
Magnetic Moments ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Lattice Curvature ◽  
Electron States ◽  
Large Atom ◽  
Transmission Electron ◽  
Large Distortion ◽  
Density Of Electron States

The article deals with the investigation of structure and magnetic properties of plastically deformed Ni51Ti49 alloy. The magnetic hysteresis loops confirm the presence of ferromagnetic properties in the alloy. The transmission electron microscopy (TEM) detects the appearance of lenticular crystals with bending contours which indicate the large distortion of the crystal lattice. The crystal lattice curvature occurs due to the large atom displacement. As a result, icosahedral clusters with the Frank-Kasper (FK) structure can be formed. The spin-polarized density of electron states and the magnetic moments for both non-deformed (near-spherical structure) and deformed (elongated by 5% along the Z-axis) Ni7Ti5 (FK-12), Ni8Ti5 (FK-13), and Ni10Ti6 (FK-16) clusters are calculated for the explanation of possibility of magnetization appearance in Ni51Ti49 alloy. The calculations show the increase in the magnetic moments for the deformed clusters. The calculated spectra demonstrate the high density of electron states near the Fermi level which is a characteristic feature of ferromagnetic alloys.

Fe-Core/Au-Shell Nanoparticles: Growth Mechanisms, Oxidation and Aging Effects

2005 ◽  
Vol 887 ◽  
Author(s):  
Kai Liu ◽  
Sung-Jin Cho ◽  
Susan M. Kauzlarich ◽  
J. C. Idrobo ◽  
Joseph E. Davies ◽  
...  
Keyword(s):  
Electrical Transport ◽  
Inductively Coupled Plasma ◽  
Magnetic Moments ◽  
Hysteresis Loops ◽  
Growth Mechanisms ◽  
Aging Effects ◽  
Contrast Imaging ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Over Time

ABSTRACTWe report the chemical synthesis of Fe-core/Au-shell nanoparticles (Fe/Au) by a reverse micelle method, and the investigation of their growth mechanisms and oxidation-resistant characteristics. The core-shell structure and the presence of the Fe and Au phases have been confirmed by transmission electron microscopy, energy dispersive spectroscopy, x-ray diffraction, Mössbauer spectroscopy, and inductively coupled plasma techniques. Additionally, atomic-resolution Z-contrast imaging and electron energy loss spectroscopy in a scanning transmission electron microscope have been used to study details of the growth processes. The Au-shells grow by nucleating on the Fe-core surfaces before coalescing. First-order reversal curves, along with the major hysteresis loops of the Fe/Au nanoparticles have been measured as a function of time in order to investigate the evolution of their magnetic properties. The magnetic moments of such nanoparticles, in the loose powder form, decrease over time due to oxidation. The less than ideal oxidation-resistance of the Au shell may have been caused by the rough Au surfaces. In a small fraction of the particles, off-centered Fe cores have been observed, which are more susceptible to oxidation. However, in the pressed pellet form, electrical transport measurements show that the particles are fairly stable, as the resistance and magnetoresistance of the pellet do not change appreciably over time. Our results demonstrate the complexity involved in the synthesis and properties of these heterostructured nanoparticles.

Underplatform Dampers for Turbine Blades: Theoretical Modeling, Analysis, and Comparison With Experimental Data

1998 ◽  
Vol 123 (4) ◽  
pp. 919-929 ◽  
Author(s):  
K. Y. Sanliturk ◽  
D. J. Ewins ◽  
A. B. Stanbridge
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Normal Load ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Hysteresis Loops ◽  
Modeling Analysis ◽  
Modes Of Vibration ◽  
Opening And Closing ◽  
Distinct Features

This paper describes a theoretical model for analyzing the dynamic characteristics of wedge-shaped underplatform dampers for turbine blades, with the objective that this model can be used to minimize the need for conducting expensive experiments for optimizing such dampers. The theoretical model presented in the paper has several distinct features to achieve this objective including: (i) it makes use of experimentally measured contact characteristics (hysteresis loops) for description of the basic contact behavior of a given material combination with representative surface finish, (ii) the damper motion between the blade platform locations is determined according to the motion of the platforms, (iii) three-dimensional damper motion is included in the model, and (iv) normal load variation across the contact surfaces during vibration is included, thereby accommodating contact opening and closing during vibration. A dedicated nonlinear vibration analysis program has been developed for this study and predictions have been verified against experimental data obtained from two test rigs. Two cantilever beams were used to simulate turbine blades with real underplatform dampers in the first experiment. The second experiment comprised real turbine blades with real underplatform damper. Correlation of the predictions and the experimental results revealed that the analysis can predict (i) the optimum damping condition, (ii) the amount of response reduction, and (iii) the natural frequency shift caused by friction dampers, all with acceptable accuracy. It has also been shown that the most commonly used underplatform dampers in practice are prone to rolling motion, an effect which reduces the damping in certain modes of vibration usually described as the lower nodal diameter bladed-disk modes.

scholarly journals Biomedical Applications of Biomaterials Functionalized with Magnetic Nanoparticles

2020 ◽  
Author(s):  
Matteo Bruno Lodi ◽  
Alessandro Fanti
Keyword(s):  
Magnetic Field ◽  
Drug Delivery ◽  
Magnetic Nanoparticles ◽  
Heat Dissipation ◽  
Hyperthermia Treatment ◽  
Prosthetic Implants ◽  
Magnetic Carriers ◽  
Magnetic Drug Delivery ◽  
Influence Parameter ◽  
Nonlinear Nature

The combination of magnetic nanoparticles and a biocompatible material leads to the manufacturing of a multifunctional and remotely controlled platform useful for diverse biomedical issues. If a static magnetic field is applied, a magnetic scaffold behaves like an attraction platform for magnetic carriers of growth factors, thus being a potential tool to enhance magnetic drug delivery in regenerative medicine. To translate in practice this potential application, a careful and critical description of the physics and the influence parameter is required. This chapter covers the mathematical modeling of the process and assesses the problem of establishing the influence of the drug delivery system on tissue regeneration. On the other hand, if a time-varying magnetic field is applied, the magnetic nanoparticles would dissipate heat, which can be exploited to perform local hyperthermia treatment on residual cancer cells in the bone tissue. To perform the treatment planning, it is necessary to account for the modeling of the intrinsic nonlinear nature of the heat dissipation dynamic in magnetic prosthetic implants. In this work, numeric experiments to investigate the physiopathological features of the biological system, linked to the properties of the nanocomposite magnetic material, to assess its effectiveness as therapeutic agents are presented.

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