Dynamic magnetic hysteresis in a liquid suspension of acicular maghemite particles

Kashevsky, B. E.; Kashevsky, S. B.; Прохоров, И. В.

doi:10.1016/j.partic.2009.09.002

Cited by 16 publications

(13 citation statements)

References 8 publications

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“…Exposure to high amplitude fields was the test condition to demonstrate the potential benefit of such regulation because this represents a challenging case. Further, currently available nanoparticle formulations typically exhibit therapeutic loss power only at high amplitudes (near magnetisation saturation) [9, 10]. …”

Section: Discussionmentioning

confidence: 99%

“…Generally, the goal of such research is to develop nanoparticle and solenoid combinations that produce a maximum particle-associated heating rate, or loss power for a given flux (peak-to-peak) magnetic field, or B -field. For many magnetic materials, the loss power increases both with increasing AMF frequency and with amplitude, thus encouraging development of devices that generate high amplitude fields for a given frequency [9, 10]. Indeed, some nanoparticle formulations produce insignificant heating unless exposed to high amplitude fields at a given frequency [9, 10], thereby motivating combinations with high frequency or high amplitude devices in research for magnetic nanoparticle hyperthermia.…”

Section: Introductionmentioning

confidence: 99%

“…For many magnetic materials, the loss power increases both with increasing AMF frequency and with amplitude, thus encouraging development of devices that generate high amplitude fields for a given frequency [9, 10]. Indeed, some nanoparticle formulations produce insignificant heating unless exposed to high amplitude fields at a given frequency [9, 10], thereby motivating combinations with high frequency or high amplitude devices in research for magnetic nanoparticle hyperthermia. While both device and nanoparticle research have accelerated in recent years, there is relatively little systematic study describing thermal management for bodies exposed to AMFs.…”

Section: Introductionmentioning

confidence: 99%

“…For cancer therapy it has been suggested that AMF can be combined with magnetic nanoparticles that are locally concentrated in cancer tissue to selectively heat the cancer [8, 28–31]. For a specific AMF frequency, the heat generated by the nanoparticles generally depends upon the magnitude or intensity of the AMF [8–10]. Thus therapeutic efficacy of such magnetic nanoparticle hyperthermia (MNH) can be enhanced with high intensity fields applied to those regions of tissue that contain tumours bearing high concentrations of magnetic nanoparticles [31].…”

Section: Introductionmentioning

confidence: 99%

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Method to reduce non-specific tissue heating of small animals in solenoid coils

Kumar¹,

Attaluri²,

Mallipudi³

et al. 2013

International Journal of Hyperthermia

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Purpose Solenoid coils that generate time-varying or alternating magnetic fields (AMFs) are used in biomedical devices for research, imaging and therapy. Interactions of AMF and tissue produce eddy currents that deposit power within tissue, thus limiting effectiveness and safety. We aim to develop methods that minimise excess heating of mice exposed to AMFs for cancer therapy experiments. Materials and methods Numerical and experimental data were obtained to characterise thermal management properties of water using a continuous, custom water jacket in a four-turn simple solenoid. Theoretical data were obtained with method-of-moments (MoM) numerical field calculations and finite element method (FEM) thermal simulations. Experimental data were obtained from gel phantoms and mice exposed to AMFs having amplitude >50kA/m and frequency of 160 kHz. Results Water has a high specific heat and thermal conductivity, is diamagnetic, polar, and nearly transparent to magnetic fields. We report at least a two-fold reduction of temperature increase from gel phantom and animal models when a continuous layer of circulating water was placed between the sample and solenoid, compared with no water. Thermal simulations indicate the superior efficiency in thermal management by the developed continuous single chamber cooling system over a double chamber non-continuous system. Further reductions of heating were obtained by regulating water temperature and flow for active cooling. Conclusions These results demonstrate the potential value of a contiguous layer of circulating water to permit sustained exposure to high intensity alternating magnetic fields at this frequency for research using small animal models exposed to AMFs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Method to reduce non-specific tissue heating of small animals in solenoid coils

Kumar¹,

Attaluri²,

Mallipudi³

et al. 2013

International Journal of Hyperthermia

View full text Add to dashboard Cite

show abstract

“…For example, the power losses (heating) from magnetic nanoparticles are field amplitude-dependent [10]–[12]; therefore, in order to accurately estimate their heating efficiency it is necessary to encompass the sample volume in a homogeneous flux-density field. Several nanoparticle power loss measurement systems have been reported [13]–[18], but most utilize a simple and often poorly described solenoid over a limited amplitude range (<30 kA/m).…”

Section: Introductionmentioning

confidence: 99%

Modified Solenoid Coil That Efficiently Produces High Amplitude AC Magnetic Fields With Enhanced Uniformity for Biomedical Applications

et al. 2012

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In this paper, we describe a modified solenoid coil that efficiently generates high amplitude alternating magnetic fields (AMF) having field uniformity (≤10%) within a 125-cm3 volume of interest. Two-dimensional finite element analysis (2D-FEA) was used to design a coil generating a targeted peak AMF amplitude along the coil axis of ~100 kA/m (peak-to-peak) at a frequency of 150 kHz while maintaining field uniformity to >90% of peak for a specified volume. This field uniformity was realized by forming the turns from cylindrical sections of copper plate and by adding flux concentrating rings to both ends of the coil. Following construction, the field profile along the axes of the coil was measured. An axial peak field value of 95.8 ± 0.4 kA/m was measured with 650 V applied to the coil and was consistent with the calculated results. The region of axial field uniformity, defined as the distance over which field ≥90% of peak, was also consistent with the simulated results. We describe the utility of such a device for calorimetric measurement of nanoparticle heating for cancer therapy and for magnetic fluid hyperthermia in small animal models of human cancer.

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Internal Magnetic Structure of Nanoparticles Dominates Time‐Dependent Relaxation Processes in a Magnetic Field

Dennis

Krycka

Borchers

et al. 2015

Adv Funct Materials

119

137

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Magnetic nanoparticles provide a unique combination of small size and responsiveness to magnetic fields making them attractive for applications in electronics, biology, and medicine. When exposed to alternating magnetic fields, magnetic nanoparticles can generate heat through loss power mechanisms that continue to challenge a complete physical description. The influence of internal nanoparticle (intracore) magnetic domain structure on relaxation remains unexplored. Within the context of potential biomedical applications, this study focuses on the dramatic differences observed among the specific loss power of three magnetic iron oxide nanoparticle constructs having comparable size and chemical composition. Analysis of polarization analyzed small angle neutron scattering data reveals unexpected and complex coupling among magnetic domains within the nanoparticle cores that influences their interactions with external magnetic fields. These results challenge the prevailing concepts in hyperthermia which limit consideration to size and shape of magnetic single domain nanoparticles.

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Dynamic magnetic hysteresis in a liquid suspension of acicular maghemite particles

Cited by 16 publications

References 8 publications

Method to reduce non-specific tissue heating of small animals in solenoid coils

Method to reduce non-specific tissue heating of small animals in solenoid coils

Modified Solenoid Coil That Efficiently Produces High Amplitude AC Magnetic Fields With Enhanced Uniformity for Biomedical Applications

Internal Magnetic Structure of Nanoparticles Dominates Time‐Dependent Relaxation Processes in a Magnetic Field

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