Submitted: March 05, 2021 | Approved: April 03, 2021 | Published: April 05, 2021
How to cite this article: Skumiel A. Influence of high frequency rotating magnetic field on the effect of heating magnetic fluid. Int J Phys Res Appl. 2021; 4: 015-018.
Copyright License: © 2021 Skumiel A. This is an open access article distributed under the Creative Commons Attribution License, which peRmits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Natural radionuclides; Yam samples; Radiological parameters; Health risks
The article describes the necessary conditions for the phenomenon of thermal energy release in a magnetic fluid placed in a high-frequency rotating magnetic field. The minimum amplitude of the magnetic field was calculated and the thermal power released (by the rotating spherical nanoparticles in the viscous medium) was estimated. The estimations were based on the assumption that the magnetic relaxation times (τN and τB) and the magnetic field rotation period (τrot) meet the condition: τN>>τrot>>τB. The principle of operation and construction of the device generating a high-frequency rotating magnetic field is described. Preliminary experimental studies were carried out using a magnetic fluid with magnetite nanoparticles that indicated magnetic relaxation as the cause of the released heat. The value of the absorption rate in the experiment and its dependence on the strength of the magnetic field were determined.
Currently, magnetic fluids (MF) are studied both from the experimental and theoretical side [1,2] due to their unique physical properties and wide application. Computer simulations [1,2] of the flows of these media through micro-channels are used in theoretical models, their instability and heat flow phenomena are investigated . Magnetic liquids containing magnetic nanoparticles (NPs) are susceptible to being controlled  by external electric and magnetic fields.
For years magnetic nanoparticles have been increasingly used in many fields of technology and in biomedicine. They are used in biomedicine in magnetic resonance imaging, drug delivery or in magnetic hyperthermia (MH). The action of MH is to achieve a local increase of temperature in target cells by local activation of magnetic nanoparticles under the influence of alternating high-frequency magnetic field.
Placing magnetic nanoparticles in a variable high-frequency magnetic field causes a thermal effect. The reason for this phenomenon is to release thermal energy in the magnetic fluid. When NPs are small particles and have only superparamagnetic properties, the main reason for the thermal effect is magnetic relaxation. The phenomenon of magnetic relaxation has been explained by the Néel mechanism and by the Brownian mechanism. Both these magnetization mechanisms occur with characteristic relaxation times(τN, τB) depending on the size of the magnetic core τm and the hydrodynamic diameter dh, as well as the properties of the magnetic material of the grain, liquid viscosity ηS and temperature T . Depending on the value of these parameters, the mechanism with a smaller relaxation time dominates. When τN>>τB, Néel’s mechanism is negligible, and this case concerns nanoparticles with slightly larger sizes. Then the rotation of the magnetization vector inside the magnetic core is practically blocked and the entire nanoparticle rotates. This means that such a particle can rotate in a rotating magnetic field (RMF), as long as the driving torque is greater than the resistance of the liquid medium.
Among the methods, the use of an oscillating magnetic field [6,7] is widespread, but recently there have been reports describing the RMF [8,9]. Because the oscillating magnetic field is relatively easy to generate (even at high frequencies), it is most often used for heating up MF. However, an RMF can yield a higher heat output  than an oscillating field at the same values of magnetic field amplitude and frequency. If a NP is placed in a RMF , it can rotate in this viscous medium and due to the friction, thermal energy is released and its temperature rises. Thus, two moments of forces act simultaneously on the nanoparticle: the driving torque Td and the torque τb from resistance forces surrounding the medium.
Mechanical driving torque Td resulting from the action of the external magnetic field on the magnetic moment MS·Vm of the NP is defined as :
where, H - is the intensity of magnetic field, Vm – volume of the magnetic core, µ0 = 4π·10-7 H·m-1 is the permeability of vacuum, MS is the saturation magnetization of the magnetic material and θ is angle between vectors H and magnetic moment.
If the sphere rotates in a viscous fluid with frequency f - without slipping relative to the RMf - the braking torque τb acts on it equals .
where dh is hydrodynamic diameter and ηS is viscosity coefficientof fluid. This situation is shown in figure 1 during the magnetic spherical NP is immersed in a viscous liquid.
The operation of these two torques leads to a rotation of the spherical nanoparticles when the following condition is fulfilled: Td > τb. When the additional condition τrot > τeff is fulfilled, then both magnetization mechanis MS (Néel and Brown) take part in heat release effect, where τrot is the period of field rotation, τeff is the effective relaxation time.
In practice, several cases of the experiment can be observed by selecting the magnetic fluid of the appropriate NPs size and magnetic field frequency, such as:
1). τN>τrot>τB, where Néel mechanism is eliminated,
2). τB>τrot>τN, where Brown mechanism is eliminated,
3). τrot>τN = τB, where both magnetization mechanisms take an equal part in MF heating.
From the comparison of the driving moment Td and the braking moment τb, we obtain the expression (3) for the minimum magnetic field strength H:
required during NP rotation without slipping relative to field rotation. This expression implies that a low required magnetic field value will be if MF has a low viscosity value and a low surfactant layer thickness.
Construction and parameters of magnetic circuits
In order to create a RMF, the author developed a measuring system (Figure 2a) consisting of two LC branches whose axes were spaced in every 900 degrees of angularity, and the electrical signals fed to them had phase shift of 900 degrees. The system used 2-channel function generators SIGLENT TECHNOLOGIES SDG1025 in which the frequency and phase were set independently in each channel. The generator’s signals from both channels controlled electronic keys. The coils were wound on ferrite cores Ferroxube I100/25/25 and the inductance of each branch was L = 1.8 mH. The HVCA capacitor with an electrical capacity of C = 8 nF was connected in series with each branch. The minimum impedance of each such branch occurred at the resonance frequency f = 41.9 kHz. Figure 2b shows the view of magnetic circuits with Liebieg cooler, which was connected to a temperature stabilization system.
In experiments, the optical fiber temperature sensor  by FISO Technology Inc., model FOT-L-SD was used with temperature range (−40 ÷ 300)°C, with response time better than 1.5 s, accuracy of 0.10°C and resolution of 0.01°C.
The voltage signal on the branches has a rectangular shape but due to the selective properties of the LC circuit, the currents flowing through the coils (also magnetic streaMS) have a sinusoidal waveform, as shown in figure 3. The visible sinusoidal voltage wave induced on one turn loop additional wound on a ferrite core corresponds to the basic distribution component of the Fourier series. Other, higher components of the series are eliminated by a bandpass filter with LC branch.
Calorimetric tests in a RMF were made in an liquid based on transformer oil with magnetite (Fe3O4) NPs coated with oleic acid. The sizes of the magnetite particles were determined using a TEM microscope and are shown in figure 4. Additional physical parameters of NPs and MF are summarized in table 1.
From the magnetization curve, the volume concentration of magnetite particles, ϕV = 2.76% was obtained. The results of fitting the log-normal function describing the distribution of NPs provided the following size values: the mean diameters <d> = 11.8 nm and the mean standard deviation <σ> = 5.0 nm. Considering the frequency of magnetic field (f = 41.9 kHz), nanoparticle sizes (τm ≅ 11.8 nm, dh ≅ 15.8 nm), carrier liquid parameters (ηS ≅ 9.7 mNs·m-2) and temperature (T = 298K), the relation between the period of magnetic field rotation in relation to the magnetic relaxation times in experiment was as follows: τrot>τB>>τN.
It follows that both mechanisms were involved in the release of heat. However, mainly the Néel’s mechanism dominated: (τrot = 24 µs) > (τB = 15 µs) >>(τN = 10 ns).
Results of calorimetric experiments and analysis
The result of the magnetic heating experiment in the RMF is presented in figure 5a for selected values of magnetic field strength amplitude. The dependence of the temperature increase rate (dT/dt)t = 0  determined by the formula (4) as a function of the amplitude of the magnetic field intensity  is shown in figure 5b.
where a = 79495 and n = 1.95 are parameters obtained from matching equation (4) to experimental data. Dotted lines show the error range resulting from matching the function to experimental data. An additional reason for the measurement error is related to the dissipation of thermal energy from the MF to the glass vial. Because the mass of MF is less than glass vial mass, the heating effect  should be corrected and Tcor = 1.72·Texp.
In order to evaluate the efficiency of the heating process of the MF under the influence of the external magnetic field, the specific loss power (SLP) was determined by the formula :
where cS =1.54 J·g-1·K-1 is the specific heat capacity of the sample, MS = 0.9498g·cm-3 and mNP = 143 mg/ml are the density of MF and magnetic material respectively.
In the experiment with a field strength of H = 4 kA·m-1 and a frequency of f = 41.9 kHz, an SLP value of 52 mW·g-1 can be obtained. The dependence of the SLP parameter on the amplitude of the magnetic field intensity is shown in figure 6.
The article presents the construction of the device for generating RMF based on the use of rectangular waveforMS shifted by 90 degrees angles and the use of a selective filter that eliminated higher components and reproduced only the basic, sinusoidal component.
The value of the exponent n = 2 in equation (4) indicates that the main source of the released thermal energy is magnetic relaxation. In addition, the tested MF sample with very small NPs exhibits superparamagnetism. Due to the use of small particles, the dominant mechanism of magnetization followed the Néel’s theory. In future heating studies with RMF, NPs larger sizes should be used and then Brown’s relaxation time will be comparable with Néel’s time. With the diameter (dm) of the magnetite core close to 19 nm and the same other parameters of the sample, both magnetization mechanisms will be equal to each other.
The present research uses spherical-shaped nanoparticles but other types of nanotubes  may find a similar application.
- Bastos RO, Pascholati EM. Environmental gamma radiation in Municipalities of Eastern of Sao Paulo State, Brazil. Terrae. 2005; 2: 37-45.
- Mokobia CE, Adebiyi FM, Akpan I, Olise FS, et al. Radioassay of prominent Nigerian fossil fuels using gamma and TXRF spectroscopy fuel. 2006; 85: 1811-1814.
- UNEP (United Nations Environment Programme): Radiation effects and sources. 2016.
- Hewitt Cn. Radioactivity in the environment, pollution: causes, effects and control, Harrison RM (ed.), The Royal Society of Chemistry. 1990.
- McDonald P, Jackson D, Leonard DRP, McKay K. An assessment of 210Pb and 210Po terrestrial foodstuffs from regions of potential technological enhancement in England and Wales. J Environ Radiat.1999; 43: 15-29.
- Fernandez G, Rodriquez IM, Castro GV, Carrazana G, Martizez RN. Radiological surveillance of foods and drinking water in the Cuban Republic, Proceeding of the 11th Conference of the International Radiation Protection Association (IRPA), Madrid, Spain. 2004.
- Vegueria SFJ, Godoy JM, Miekeley N. Environmental impact studies of oil-field offshore platforMS. Brazil J Environ Radioact. 2002; 62: 29-38.
- Smith KP, Blunt DL, WilliaMS GP, Arnish JJ, Pfingston M, et al. An assessment of the disposal of petroleum industry NORM in non-hazardous Landfills. National Petroleum Technology Office, US Department of Energy Report No-DOE/BC/W-31-109-ENG-38-8. 1999.
- NPC (National Population Commission): National Population Census Figures, Abuja, Nigeria. 2006.
- ISMLS (Imo State Ministry of Lands and Survey): Imo State Ministry of Lands and Survey Publication. 2009.
- Okodili N. The other side of Imo oil tale. The Nation. 2014.
- Owuamanam JA. Imo community threatens to shut oil firm for neglect. Daily Trust. 2019.
- Farai IP, Jibiri NN. Baseline studies of terrestrial outdoor gamma dose rate levels in Nigeria. Radiat Prot Dosim. 2000; 88: 247-254.
- Jibiri NN. Assessment of health risk levels associated with terrestrial gamma radiation dose rates in Nigeria. Environ Int. 2001; 27: 21-26. PubMed: https://pubmed.ncbi.nlm.nih.gov/11488386/
- Farai IP, Obed RI, Jibiri NN. Soil radioactivity and incidence of cancer in Nigeria. J Environ Radioact. 2006; 90: 29-36. PubMed: https://pubmed.ncbi.nlm.nih.gov/16859817/
- Akhionbare AE, Osuji EE. Effect of oil exploration on socio-cultural issues in Oguta Local Government Area of Imo State. Nigeria J Environ Issues Agric Dev Ctries. 2013; 5: 19-24.
- Jibiri NN, Emelue HU. Soil radionuclide concentrations and radiological assessment in and around a refining and petrochemical company in Warri, Niger Delta, Nigeria. J Radiol Prot. 2008; 28: 361-368. PubMed: https://pubmed.ncbi.nlm.nih.gov/18714134/
- Olomo JB, Akinloye MK, Balogun FA. Distribution of gamma-emitting natural radionuclides in soils and water around nuclear research establishments, Ile-Ife, Nigeria. Nucl Instrum Method. 1994; 353: 553-557.
- Akinloye MK, Olomo JB. The measurement of the natural radioactivity in some tubers cultivated in farmlands within the Obafemi Awolowo University Ile-Ife, Nigeria. Nig J Phys. 2000; 12: 60-63.
- Jibiri NN, Farai IP, Alausa SK. Estimation of annual effective dose due to natural radioactive elements in ingestions of foodstuffs in tin mining area of Jos-Plateau, Nigeria. J Environ Radioact. 2007; 94: 31-40. PubMed: https://pubmed.ncbi.nlm.nih.gov/17337103/
- ICRP (International Commission on Radiological Protection): Dose co-efficient for the intakes of radionuclides by workers (ICRP Pub. No. 68), Pergamon Press. Oxford. 1994.
- ICRP (International Commission on Radiological Protection): Age-dependent doses to members of the public from intake of radionuclides: Part 5, Compilation of ingestion and inhalation dose co-efficient (ICRP Pub. No. 72), Pergamon Press, Oxford. 1996.
- RIFE (Radioactivity in Food and the Environment): The center for environment, fisheries and aquaculture science (CEFAS), Radioactivity in food and the environment, 2004 Report. RIFE-10. 2005.
- FOS (Federal Office of StatisticS Nigeria): Compilation of FOS/FAO annual consumption data/food balance sheet of Nigeria, A publication of Federal Office of StatisticS (FOS), Nigeria. 2006.
- Bamgboye EA. Sample size determination, in: A comparison of medical statisticS, third ed. Folbam Publishers. Ibadan. 2008: 156.
- Dacie JV, Lewis SM. Practical haematology, Churchill Livingstone, London. 1991: 50-56.
- Osim EE, Akpogomeh BA, Ibu JO, Eno AE. Experimental physiology manual, Department of Physiology, University of Calabar, Calabar, third ed. 2004; 60-81.
- AcS (American Cancer Society): Understanding your lab test results, 2017.
- AACC (American Association for Clinical Chemistry): Understanding your tests, 2012.
- Jibiri NN, Abiodun TH. Effects of food diet preparation techniques on radionuclide intake and its implications for individual ingestion effective dose in Abeokuta, Southwestern Nigeria. World J Nucl Sci Technol. 2012; 2: 106-113.
- Nwankpa AC. Determination of food crops contamination in Osun State, Nigeria due to radium-226, thorium-232 and potassium-40 concentrations in the environment. Eur J Sustain Dev. 2017; 6: 169-174.
- Jwanbot DI, Izam MM, Nyam GG. Radioactivity in some food crops from high background radiation area on the Jos-Plateau, Nigeria. J Nat Sci Res. 2012; 2: 76-79.
- Avwiri GO, Agbalagba EO. Assessment of natural radioactivity, associated radiological health hazards indices and soil-to-crop transfer factors in cultivated area around a fertilizer factory in Onne, Nigeria. Environ Earth Sci. 2014; 71: 1541-1549.
- Gilbert AI, Olanrewaju A, Olawale IA, Aremu RO, Omosebi IAA. Measurement of (40K, 238U and 232Th) and associated dose rates in soil and commonly consumed foods (vegetables and tubers) at Okitipupa, Ondo State, Southwestern Nigeria. Asian J Res Rev Phys. 2018; 1: 1-11.
- IARC (International Agency for Research on Cancer): IARC monographs on the evaluation of carcinogenic risks to humans, Ionizing Radiation, Part 1: x- and γ-radiation and neutrons. 2000; 75.
- Cancer Registry Unit, University of Nigeria Teaching Hospital (UNTH) Enugu, 2016.
- Sharma M, Sachdeva MUS, Bose P, Varma N, Varma S, et al. Haematological profile of patients with mixed-phenotype acute leukaemia from a tertiary care centre of North India. Indian J Med Res. 2017; 145: 215-221. PubMed: https://pubmed.ncbi.nlm.nih.gov/28639598/
- Ghosh S, Shinde SC, Kumaran GS, Sapre RS, dhond SR, et al. Hematologic and immunophenotypic profile of acute myeloid leukaemia: an experience of Tata Memorial Hospital. Indian J Cancer. 2003; 40: 71-76. PubMed: https://pubmed.ncbi.nlm.nih.gov/14716122/
- Hasan KM, Al-Allawi NAS, Badi AIA. Multilineage dysplasia in Iraqi Kurds with acute myeloid leukaemia: a retrospective study on 105 patients. Duhok Med J. 2017; 11: 1-10.
- Pouls RK, Shamoon RP, Muhammed NS. Clinical and haematological parameters in adult AML patients: a four year experience at Nanakaly Hospital for blood diseases. Zanco J Med Sci. 2012; 16: 199-203.
- Salim BW, Jalal SD. Immunological profile of acute myeloid leukaemia in Kurdistan Iraq. Duhok Med J. 2018; 12: 1-12.
- Sadiq MA, ShaMShad GU, Ali, N, Ghani, E, Ahmed, S, Arshad, M. Haematological manifestations and frequency of FAB subtypes in patients of acute myeloid leukaemia: single centre study. Pak Armed Forces Med J. 2015; 65: 610-615.