Critical RF losses in fine particles of La1−xAgyMnO3+δ: Prospects for temperature-controlled hyperthermia

Ацаркин, В. А.; Generalov, Andrey; Демидов, В. В.; Mefed, A. E.; Markelova, M. N.; Gorbenko, O. Yu.; Kaul, A. R.; Roy, Edward J.; Odintsov, B. M.

doi:10.1016/j.jmmm.2009.05.043

Cited by 13 publications

(4 citation statements)

References 21 publications

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“…Apart from a few customized systems [26][27][28], there exist no commercially available systems for performing high frequency hysteresis measurements which leads to a requirement of data extrapolation that is often inaccurate due to inherent non-linearly of the magnetization dynamics involved. On the other hand, for AC susceptibility measurements, though several high frequency systems are available [26,29,30] the limiting factor is the applied magn etic field strength which is often limited to <0.5 kA m −1 [24] and hence, requires extrapolation of the measured data to higher field amplitudes, leading to possible inaccuracies. Though better systems are being developed [26], the uncertainties in both the above mentioned magnetic measurement techniques make the traditional calorimetric measurements the most widely used and universally accepted experimental technique for SAR determination using the following equation [1,19].…”

Section: Introductionmentioning

confidence: 99%

Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

Lahiri

Ranoo

Philip

2017

J. Phys. D: Appl. Phys.

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Magnetic fluid hyperthermia (MFH) is becoming a viable cancer treatment methodology where the alternating magnetic field induced heating of magnetic fluid is utilized for ablating the cancerous cells or making them more susceptible to the conventional treatments. The heating efficiency in MFH is quantified in terms of specific absorption rate (SAR), which is defined as the heating power generated per unit mass. In majority of the experimental studies, SAR is evaluated from the temperature rise curves, obtained under non-adiabatic experimental conditions, which is prone to various thermodynamic uncertainties. A proper understanding of the experimental uncertainties and its remedies is a prerequisite for obtaining accurate and reproducible SAR. Here, we study the thermodynamic uncertainties associated with peripheral heating, delayed heating, heat loss from the sample and spatial variation in the temperature profile within the sample. Using first order approximations, an adiabatic reconstruction protocol for the measured temperature rise curves is developed for SAR estimation, which is found to be in good agreement with those obtained from the computationally intense slope corrected method. Our experimental findings clearly show that the peripheral and delayed heating are due to radiation heat transfer from the heating coils and slower response time of the sensor, respectively. Our results suggest that the peripheral heating is linearly proportional to the sample area to volume ratio and coil temperature. It is also observed that peripheral heating decreases in presence of a non-magnetic insulating shielding. The delayed heating is found to contribute up to ~25% uncertainties in SAR values. As the SAR values are very sensitive to the initial slope determination method, explicit mention of the range of linear regression analysis is appropriate to reproduce the results. The effect of sample volume to area ratio on linear heat loss rate is systematically studied and the results are compared using a lumped system thermal model. The various uncertainties involved in SAR estimation are categorized as material uncertainties, thermodynamic uncertainties and parametric uncertainties. The adiabatic reconstruction is found to decrease the uncertainties in SAR measurement by approximately three times. Additionally, a set of experimental guidelines for accurate SAR estimation using adiabatic reconstruction protocol is also recommended. These results warrant a universal experimental and data analysis protocol for SAR measurements during field induced heating of magnetic fluids under non-adiabatic conditions.

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Section: Introductionmentioning

confidence: 99%

Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

Lahiri

Ranoo

Philip

2017

J. Phys. D: Appl. Phys.

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“…for La 3+ causes an increase in Mn ସା fraction and thereby an increase in the number of Mn ଷା − Mn ସା ion pairs, leading to a stronger doubleexchange interaction and consequently higher ܶ େ [8]. Some researchers have discussed about the prospects of La ଵି௫ Ag ௫ MnO ଷାஔ [9,10] NPs as suitable candidates for temperature-controlled hyperthermia treatments. Since these samples show magnetic transition above the temperature required for hyperthermia treatments, the heating mechanism of microwave absorption is found useful for them.…”

Section: Introductionmentioning

confidence: 99%

Studies on characteristic properties of superparamagnetic La 0.67 Sr 0.33−x K x MnO 3 nanoparticles

Keshri

Wiśniewski

2016

Journal of Alloys and Compounds

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“…For example, Hopkinson peaks were determined by ac susceptibility measurements for La 1Àx Ag y MnO 3+D particles with diameters >200 nm. 30 To our knowledge, our report is the first experimental evidence of the Hopkinson peak in LSMO nanoparticles, and the first experimental determination of this effect by calorimetric measurements.…”

Section: Temperature Dependence Of Sarmentioning

confidence: 68%

New insights into the heating mechanisms and self-regulating abilities of manganite perovskite nanoparticles suitable for magnetic fluid hyperthermia

et al. 2012

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The heating and self-regulating abilities of La(1-x)Sr(x)MnO(3+Δ) ferromagnetic nanoparticles for magnetic fluid hyperthermia are studied. The samples, synthesized by the Glycine Nitrate Process, present non-agglomerated particles but are partially constituted by polycrystalline nanoparticles, displaying average crystallite diameters ranging from 21 to 31 nm. The strontium content of these nanoparticles, between 0.14 and 0.39, is associated with non-stoichiometry effects in the materials, and both govern their Curie temperatures (T(C)), which range between 13 and 86 °C, respectively. Heating experiments carried out on samples suspended in an aqueous agarose gel and with different alternating magnetic fields derive unexpected maximum temperatures that cannot be explained on the basis of static magnetization data. The measurement of the thermal dependence of the specific absorption rate (SAR) of nanopowders by adiabatic magnetothermia reveals the existence of a dissipation peak just below T(C), which is assigned to a Hopkinson peak. This thermal dependence of SAR, together with a simple thermal model that considers a linear approximation for the heat power losses, is crucial to clarify the behavior observed in heating experiments and also to discuss the possibilities of the samples as self-regulating hyperthermia mediators. This analysis emphasizes that, for the correct design of a self-regulating system, the heat power losses determined by the surrounding conditions must be taken into account as well as the heating capacity of the magnetic nanoparticles.

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Critical RF losses in fine particles of La1−xAgyMnO3+δ: Prospects for temperature-controlled hyperthermia

Cited by 13 publications

References 21 publications

Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

Studies on characteristic properties of superparamagnetic La 0.67 Sr 0.33−x K x MnO 3 nanoparticles

New insights into the heating mechanisms and self-regulating abilities of manganite perovskite nanoparticles suitable for magnetic fluid hyperthermia

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