[0001 J The present application claims priority from Australian Provisional Patent

Application No 2013905012 filed- on 20 December 2013, the content of which is incorporated herein by reference.

Technical Field

[0002] The present disclosure relates to magnetic materials and remote heating using magnetic, materials.

Background

[0003] Magnetic materials such as superparamagnetic materials (e.g., magnetite nanoparticles) and magnetic materials exhibiting a second-order magnetic transition (e.g., metallic Iron and fenites) have been used for remote heating. A magnetic field is applied to the magnetic material which induces heat output from the magnetic material.

[0004] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field rele vant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0005] In one aspect, the present disclosure provides a magnetic heating system comprising:

ferromagnetic material exhibiting a first-order magnetic, transition; and

a magnetic field generator adapted to apply an alternating magnetic field to the ferromagnetic material to induce heat emission from the ferromagnetic material.

[0006] In another aspect, the present disclosure provides a method of heating comprising:

applying an alternating magnetic field to a ferromagnetic material t induce heat emission from, the ferromagnetic material, the fen'omagtietic material exhibiting a first-order magnetic transition,

[0007] A heating system and method according to the present disclosure can provide a substantially stronger heating effect than existing arrangements by utilising an extraordinary magnetic transition process known as the first-order magnetic transition. The ferromagnetic material of the present disclosure exhibits a first-order magnetic transition and this is accompanied by an abrupt change in the spontaneous magnet ization. This abrupt change provides a significantly enhanced heating effect just below the magnetic transition temperature, also known as the Curie temperature {¾), which temperature may be selected or tuned depending on desired heating purposes,

[0008] Under corresponding magnetic field conditions, the ferromagnetic material of the present disclosure may provide heating power of at least an order of magnitude greater than current materials used for magnetic heating.

[0009] The magnetic heating system and method, may be configured to provide medical treatment. For example, the magnetic material ma be provided in an implant and/or in the form of nanoparti.cles, and may be located, by injection or other implantation procedure, within a human or animal body. Using the magnetic field generator, heat output from the magnetic material can be controlled remotely, from a position external to the body, in some embodiments, the beat is used to provide a therapeutic effect

[0010] The system, and method may be adapted to provide hyperthermia therapy, which can be used to treat cancer. The ferromagnetic material can be injected int or implanted in or adjacent a tumour. The surrounding tumour tissue is heated by the ferromagnetic material, killing tumour cells without substantial damage- to healthy tissue.

[001 1 j For the purposes of hyperthermia therapy or otherwise, the magnetic material may be adapted to provide for heating above body temperature. Heating cancer cells t a temperature above body temperature, e.g. a temperature greater than 40°C, can cause cell damage or apoptosis. The temperature to which tissue or other medium are heated can be substantially dependent on the Curie temperat ure of the ferromagnetic material. The Curie temperature of the ferromagnetic material may therefore be selected to be greater' than 40°C. Nevertheless, depending on the intended purpose' of the heating, whether for medical treatment or otherwise, th feiTOmagnetie material may be selected to have one of a variety o different Curie Temperatures. For example, the Curie Temperature may be between 20 and 80°C, 40 and 60 ^: 'C, 40 and 50°G or otherwise. In one embodiment of the present disclosure, the Curie temperature of the ferromagnetic material is 46.1°C

[0012] Embodiments of the present disclosure are not necessarily limited to medical use. They can have applications in an field where remote heating is desirable. A one example, they may be used in heat assisted forward osmosis water desalination technology.

[00133 Particularly, although not necessarily exclusively, for the purpose of medical treatment, the magnetic field generator can be adapted to apply an alternating magnetic field having an effective field strength in the order of 10 ⁹ A/(ms), For example, the magnetic field generator may be adapted to apply an alternating magnetic field having an effective field strength of from about 4.85 x 10 ^s A (ms) to about 5 x lO ⁹ A/(ms).

[0014] The substantially high heating power of the ferromagnetic material can mean medical treatment is less invasive, since lower applied magnetic field strength may be required, to achieve a desired heating effect.

[00153 In ° ^ne aspect of the present disclosure there is provided an injectable composition comprising ferromagnetic material exhibiting a first-order magnetic transition.

[0016] In another aspect of the present disclosure there is provided an implant comprising ferromagnetic material exhibiting a first-order magnetic transition.

[00.17 j In yet another aspect of the present disclosure there is provided use of a

ferromagnetic material exhibiting a first-order magnetic transition in a method of medical treatment.

[0018 _. ] In yet another aspect of the present disclosure there is provided use of a

ferromagnetic material exhibiting a first-order magnetic transition, in a heat assisted forward osmosis water desalination process. [001 1 In aspects of the present disclosure, any ferromagnetic material that exhibits a first- order magnetic transition, and which, can undergo magnetic transition at a temperature similar to a temperature at which heating is desired, may be used. The ferromagnetic material may be a La-Fe-Si based material. The ferromagnetic material may be a compound havi ng the formula La(Fe,Si)rj. As an alternative example, the ferromagnetic material may be a Mn-Fe- P based material. The ferromagnetic material may be a compound having the formula MnFej, _s Co _x Pi_ _y Ge _j ,, As a further example, the ferromagnetic materia! may he a Mn-As-Sb based material. The ferromagnetic material may be a compound having the formula MnAsi _-x .Sh _x .

[0020] A hydrogenation: or dehydrogenation process may be used to tune the Curie temperature. Using La-Fe-Si based material as an example, the ferromagnetic material may therefore be a hydrided compound having the formula La(Fe,Si)r,Hy, To achieve desired heating levels for therapeutic purposes, y may be between 1.4 and 2.4, between 1.6 and 2.0, equal to or above 1.7, between 1.7 and 2.0, between 1.7 and 1.9, between 1.7 and 1.8 or about 1 ,75, for example.

[0021 j According to one aspect of the disclosure, there is provided a compound of the formula La(Fe,Si)i;sH _y where v is equal to or greater than 1.7 _.

[0022] According to one aspect of the disclosure, there is provided a compound of the formula La(Fe,Si)i:iHi, s.

J _. 0023] in one embodiment, a compound of the formula La(Fe,Si)i3Hi.75 exhibits a curie temperature of 46.1°C, which may be particularly suitable for hyperthermia therapy, for example.

[0024] Throughout this specification the word "comprise", or variations such a "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

Brief Description of Draw ings

[0025] B way of example only, embodiments are now described with reference to the accompanying drawings, in which: [00261 Fig- i shows the relationship between the magnetic polarisation (M) of a ferromagnetic material avid a statically applied magnetic field (H);

[0027] Fig. 2 shows temperature dependence of spontaneous magnetisation of second-order ferromagnetic material and represents the mechanism of self-controlled heating;

[0028] Fig, 3 shows temperature dependence of spontaneous magnetisation of first-order ferromagnetic, material and represents the mechanism of self-control ted heating;

[0029] Fig. 4 shows static hysteresis loss for a first-order: ferromagnetic material over temperature, and also magnetisation of the first-order ferromagnetic material over temperatures (inset);

[0030] f¾- 5 shows temperature over time of water containing pul verised first-orde ferromagnetic material under an applied alternating magnetic field;

[0031 ] Fig. 6 shows specific heat absorption rates of different magnetic samples at different magnetic field strengths;

[0032] Fig. 7a shows temperature dependence of magnetisation for Fc-tuned La Fe,Si)j3 compounds and Fig. 7b shows the relationship between the Curie temperature and the hydrogen concentration <· ·). for LaFen.37Sii.43Hy.

[0033] Figs, 8a and 8b illustrate a heating system configured to provide hyperthermia therapy according to an embodiment of the present disclosure;

[0034] Figs, 9a and 9b illustrate a heating system configured to provide hyperthermia therapy according to another embodiment of the present disclosure; and

[0035] Fig. 10 shows a relationship between the magnetic polarisation (M) of first order ferromagnetic material and a statically applied magnetic field (H) at various different in easure ment temperatures ,

Description of Embodi mente [00361 Ferromagnetic materials exhibiting a first-order magnetic transition have a. large isothermal entrop change (AS) or adiabatie temperature change induced by a pseudo-static magnetic field. This is known as the magnetocatoric effect. The inventors have determined that these materials can be particularly useful in heating applications, and irreversible heating power of these materials can be enhanced dramatically by exposure to alternating magnetic fields. These ferromagnetic materials can be particularly advantageous for use in medical treatment, such as hyperthermia treatment, al though they can have applications in other fields where heating is desired, such as a heat assisted forward osmosis water desalination technology.

[0037] A ferromagnetic material with a first-order magnetic transition (Tc) _> undergoes an anomalous increase near .the transition temperature. It has been found that hysteresis loss can be enhanced b 800% through use of first-order ferromagnetic materials, over a narrow ^' temperature range (e.g., 2 to 3 K) immediately below Tc< Since the transition temperature of the ferromagnetic material can be tuneable over a wide temperature range that includes human body temperature, the unique hysteresis loss enhancement at, the first-order magnetic transition can result in a very abrupt increase in the magnetic heating power at an ideal therapeutic temperature, e.g. an ideal temperature for hyperthermia treatment. The heating effect is self -regulated by the Curie temperature under an alternating magnetic field, leading to a new approach to magnetic heating in applications such as hyperthermia therapy for cancer treatment,

[0038] To aid understanding of embodiments of present disclosure, heating mechanisms of certain magnetic materials are now described.

[0039] Fig. .1 shows schematically the relationship between the magnetic polarisation (M) of a ferromagnetic material and a statically applied magnetic field (H). The magnetic polarisation shows a tendency to increase with increasing applied magnetic field; however, the M value is saturated at H - ¾ the anisotropy field. The reverse magnetic field to depolarise the magnetisation from. M, to zer is defined by the coercivity (HJ. The coercivity is. known to be highly dependent on the grain size in the nanoscale regime because the magnetic correlation length of material ^' s is usually between 10 and 100 nm. The energy loss associated with the static magnetic polarisation process in a ferromagnetic (Δ£) is given by the area inside the loop, i.e. : ΔΒ - t HdM , Equation I where ^is the penneahility of free space,

[00401 When the maximum magnetic field applied is lower than H* (as illustrated by the minor loops In Fig.1), the magnetisation curve becomes unsaturated and thus, the coercive field is smaller than H ₀ leading to a smaller area inside the μ Μ- loop as compared with the saturated loop. The energy loss per unit time (P) under an alternating magnetic field is given by the area inside the loop (ΔΕ) multiplied by the frequency (AE-fi and this corresponds to the heating power.

[0041. ] The effect of the maximum external magnetic field on the area inside the hysteresis curve explains the field dependence of the heating power, Fig. 1 indicates that a large &E value is obtained by choosin a material with large. Μ _» and H _c values while tuning the external field to i¾- The maximum magnetic field allowed in hyperthermia may be capped by the condition H-f~ 1Q ⁹ A/ims), where the product of the applied field H and frequency f is the effective magnetic field. Hence, the ideal ¾ value for the maximum heating power depends on the frequency.

[0042 j The heating mechanism of superparamagnetic nanoparticles, however, is quite different from that of ferromagnetic materials. The M-H curve of materials in a

superparamagnetic state is known to follow the Langevin function and the field dependence of the magnetic polarisation is full reversible. Thus, unlike ferromagnetic materials, the M-H curve of superparamagnetic material does not exhibit any hysteresis beha viour under a static magnetisation process. The primary cause of the heating effect in superparamagnetic particles is the relaxation behaviour of the magnetisation direction in particles which result in a certain phase shift between the alternating l!ai Άηά μοΜ(ί) signals,

100431 In contrast to each of the above-described techniques, embodiments of the present disclosure utilise a ferromagnetic material to which an alternating magnetic field is applied. While a loss mechanism as described above with reference to Fig. 1 is therefore applicable, it is not the onl loss mechanism. Since magnetisation polarisation is induced by the change in the magnetic domain configurations which is -time dependent, the response of the magnetic polarisation, to external alternating magnetic field shows a finite time delay due to the domain relaxation process. This delay causes a certain phase shift between Hit) and μο Μ(ί) which C be described b a complex magnetic permeability ; the power lass is related to the imaginary part of the permeability. Hence, the area inside the M-H loop under an alternating magnetic field is far larger than under a static field. This effect is significant at high frequencies and the power loss per cycle can be enhanced by 2 order of magnitude in the kHz range in some soft magnetic materials, for example. Heating power of magnetic materials may therefore be enhanced dramatically by increasin the dri ving frequency.

[0044] The use of ferromagnetic materials allow for self-controlled heating. In. particular, in addition to the potential for large heating power, ferromagnetic materials can self-regulate heating power closer to the Curie temperature (7c). This offers a considerable advantage over heating by superparamagnetic particles with which the temperature is controlled by adjusting the applied field strength.

[0045] The mechanism of self-controlled heating in conventional second-order

ferromagnetic material is represented in Fig, 2, in which the temperature dependence of the spontaneous magnetisation- of the ferromagnetic material is shown schematically. The spon taneous magnetisation (M _s ) is given by the vector sum of the atomic magnetic moment

[0046] Although the atomic magnetic moments are strongly correlated at low temperature, via the positive exchange interaction, and the vector sum M _s is large, the spontaneous magnetisation shows negative temperature dependence because of the thermal vibration at higher temperatures. The effect of the exchange interaction is lost completely at the Carte temperature (7c) a d the atomic magnetic moments above T are oriented at random, resulting in. zero M _s . Consequently, the hysteresis loss of feiTomagnetic; particles defined by Equation 1 is lost at T = Tc and the heating power is switched off at o. Naturally, the heatin power recovers when the particles are cooled below T . Since of ferromagnetic materials can be adjusted to a therapeutic temperature, this process can be particulaii helpful in heating systems, e.g., where the material may be implanted in a subject for medical treatment, such as hyperthermia treatment. [00471 The present disclosure further recognises, however, that magnetic heatin

mechanisms with Target' heating power can. be realised at desired temperatures, e.g.

therapeutic temperatures, by using material exhibiting a first-order magnetic transition.

[0048] The temperature dependence of , in ferromagnetic materials with a second-order magnetic transition is described well by mean field theory and the normalised temperature dependence, i.e. M _s (T)/M. _s (0) vcrm T T of feff ©magnetic materials is described universally by the Brilkmm function which gives a gradual decrease in M, near T _c . Given the fact that the difference between the body temperature and the therapeutic temperature (e.g., 43 - 47 °C) is relatively small, M„ and thus the heating power of ferromagnetic materials having their Tc at the therapeutic temperature, is already quite limited at body temperature. This is the major limiting factor .in the. self-eontroljed hearing by ferromagnetic materials.

[0049] The problem of the suppressed M _s value at body temperature remains when a variety of different fcrromagnets are used, due to their temperature dependence following the Brilloum function,

[0050] However, ferromagnetic materials according to the present disclosure, exhibiting first-order magnetic transition, have a temperature dependence for M _s near T that does not follow the Brilloum function. One example of such ferromagnetic material according to the present disclosure is a La(Fe,Si)i;? compound.

[0051] Fig, 3 shows schematically the temperature dependence of M _s for a ferromagnetic material with the first-order magnetic transition at T . Unlike the second-order magnetic transition at Tc represented in Fig. 2, where the ferromagnetic order of spins diminishes cooperatively at a critical temperature, both ferromagnetic and paramagnetic phases may coexist in the 1 ^st order materials near Tc (Fig. 3) and the abrupt decrease of M _s is governed by the nucleation-and-growth process of the paramagnetic phase in the ferromagnetic matrix rather than the molecular field in the ferromagnetic phase. Hence, the decrease in the spontaneous magnetisation near T can be very abrupt. La(Fe,Si) ^' i3 has a very steep change of M _s due to the presence of such a first-order magnetic transition.

[0052] Through creative research, the present inventors have become aware that ferromagnetic materials exhibiting first-order magnetic transitio have been used in magnetic refrigeration applications, which is a considerably different application and. field of technology to embodiments described herein. The refrigeration process relies: on static magnetic fields to ensure adequate heat exchange, and takes advantage of the step change of the magnetic enthalpy of the ferromagnetic material in an applied magnetic field that can induce a sudden cooling of the material near the magnetic transition.

[0053] However, the present inventors have determined that ferromagnetic materials exhibiting first-order magnetic transition can offer considerable advantages ^' as a medium for self-controlled isothermal heating, e.g. for use in medical treatment, and have determined that considerable benefits can be achieved through the application of an altern ting magnetic field to the ferromagnetic material to induce heating.

[0054] According to an embodiment of the present disclosure, a melt-spun La-Fe-Si based sample was prepared and tuned by hydragenation. such that it had a T value of 46.1°C (The La-Fe-Si compound had the formula LaFe-n «7811. 3-111 _, 75 in this instance.) p of 46. C was. calculated through measurement of magnetisation over a range of temperatures, as shown in the inset of Fig. 4.

[0055] M-H curves of a rate of 1.6 x 1.0 ^"3 K s, at different measurement temperatures, are shown in Fig. 10. The 1 ^st order magnetic transition is reflected in .the shape of the M-H. curves. The M-H curves well below T

(46. PC) show little irreversibility whereas the irreversibility is pronounced considerably between 42 and 46 °C, immediately below Tc. However, no appreciable increase in the eoereivity is evident on the M-H. curves at these temperatures, indicating that this hysteretic behavior is unrelated to conventional magnetic hardening caused by the magnetic amsotropy. Rather, this enhanced irreversibility near r _c is attributable to the phase coexistence where the ferromagnetic phase is induced in a matrix of the paramagnetic phase by an external magnetic field. The ni cleation-and-gi'owth process associated with the magnetic phase transition usually requires stress accommodation, adding an extra irreversibility to the Curie transition. Although this irreversibility on the -H curve is often problematic when this compound is. applied for magnetic refrigeration, this very effect due to the l ^sl Order transition i ideal for enhancing the loss power in the vicinity of TQ [00561 Fig. 4 also shows the static hysteresis loss for the ferromagnetic material, over a temperature measurement range including and extending beyond the range shown, in. Fig. 1.0. As can be seen over the wider temperature range, the hysteresis loss shows a tendency to decrease gradually as temperature increases towards ?c because both the spontaneous magnetisation and the intrinsic coereivity normally have negative temperature dependence. However, the hysteresis loss of the sample exhibited an increase in a temperature range of between 42 and 46°C as indicated above and a particularly dramatic increase (by about 800 ) in a very narrow temperature range of between 44 and 46 ⁶ C This anomalous behaviour had not previously been recognised and the inventors recognised that the dramatic ^' increase of the hysteresis loss indicated that the heating power of this first-order ferromagnetic material could be even greater unde the application of alternating magnetic field, in. consideration of higher dynamic loss that would be induced.

[0057] Heating power of the sample was subsequently analysed. The temperature of water containing the sample, in a pulverised form at a concentration of 10 mg/cc, was measured under an applied alternating magnetic field of 56 Oe (4.5 kA/m) at 279 kHz, [ -f = 1.25 x 1.0 ⁹ A/(ms)] using a infrared thermometer. The results are presented in Fig. 5. Results for commercially available magnetite (F^-G*) powders suspended in water with the same concentration are also shown in Fig. 5 for comparison.

[0058] The speed of increase of the temperature of the Tc-tuncd La(Fe,Si)i 3 -containing water or the La(Fe,.Si)iaHi s-eontaming water was dramatic between room temperature and the therapeutic, temperature range, the increase taking about one minute. In contrast, for the same time period, the magneti te provided a temperature increase of les than .1 ^a C The result highlighted the significantly greater heating effect caused by the "first-Order" ferromagnetic sample. Despite the dramatic initial heating power using thi type of sample, water temperature remained well-regulated thereafter due to the switching effect at the fine-tuned Tc-

[0059] Specific heat absorption rates of the La(Fe,Si)uHi7 _? s sample were calculated at different magnetic fields and compared with conventional magnetic samples types. The results are shown in Table 1 below and represented graphically in Fig. 6. As can be seen, the La(Fe,Si)i3Hj _, .75 sample had a specific heat absorption rate that was an order of magnitude higher than the conventional magnetic materials Table 1

Implam H(k.\ n) Frequency H.fixVf) Conceniriition SAR (W/gr)

Hall Prob /(kHz) (mg ral)

Lal¾) i siSi) .43~Hi.75* 279 9 10 64.2

( ^' l¾t _l .5vSi|.*3-H, _. 75* 4,5 279 12.5 10 23.1 .8 8.8 279 25 10 521 .5

LaFe ( -. jvSii H _{! /} 1.7-7 279 50 10 543.1

279 9 10 3,4

MgFe,0. _t ** 4.5 279 12.5 10 6.7

MgFe ₂ 0 ₄ ** 8.8 279 25 10 19.6

Mgi¾ ₂ 0 ₄ ** 17.7 279 50 10 37.7 i¾A*** 4.5 279 12.5 10 1.3

8.8 279 25 10 10. ?

*LaFei ₃ . 7Si i _ ;;-Hi.75 : ribbons prepared by melt spinning process

** MgFe _¾ 0 ₄ : Magnesium fenite nanoparticles prepared by ultrasonic assisted co- precipitation method

*** ^· ρ _β3 0 ₄ ; Magnetite nanoparticles, Sigma Aldrich - 637106 - Iron oxide (ii.iii) nanopowde.r, <50 nrti particle size (TEM), >98% trace metals basis

[0060] While La(Fe,Si)i ₃ Hi.75 with a Tc of 46.1 °C has been discussed above, this Tc value being considered as potentially ideal for hyperthermia therapy application, in other embodiments: La(Fe,Si)i3 Hi ₇₃ with different ratios of Fe and Si and/or with different Tctn y be used, e,g. depending on the desired heating temperatures (e.g. the desired therapeutic temperatures) or otherwise,

[0061 j The temperature dependence of magnetization for 7c:-tuned hydrided. La(Fe,Si)i3 compounds w s: analysed and the results are presented in Fig. 7a. The values of F _c

determined for these compounds were 3S0 K, 31.9 , 252 K and 204 K. The relationship between the Curie temperature and the hydrogen concentration (v) for LaFcn.57Si1.43Hy is shown i Fig. 7b. Some literature values reported by Lyuhimi et at (Journal of Magnetism and Magnetic ^' Materials vol. 320 (2008) pp. 2252- 2258) are also included in tire plots for comparison. T for La(Fe,Si)i3 was found to be readily tunable between 200 K (-73 °Q and 350 (77 ^U C) by controlling the hydrogen content. Thus, depending on the application, a Curie temperature may be selected that falls within a variety of different ranges. As examples only, the selected T _e may be between 20 and 80°C, 40 and 60°C, 40 and 50°C or otherwise. As examples only, y may be between 1.4 and 2,4, between 1.6 and 2.0, equal to or above 1.7, between 1.7 and 2.0, betwee 1.7 and 1.9, between 1.7 and 1.8 or about 1.75. f 0062] Other ferromagnetic compounds that are ^' not based on La-Si- Fe, but which also exhibit a first-order magnetic transition, may be employed in embodiments of the present disclosure. The ferromagnetic material may be a Mn-Fe-P based material, for example, having the formula MnFei. _x Co _x Pi. _y Gey. As another example, the ferromagnetic material may be a Mn-As-Sb based material having the formula MnAsi-xSb*. These first-order ferromagnetic materials have 7c in the ranges extending from about 176K to 323K n the case of MnFei- _x Co _x Pj. _y Gc _y (E. Brack et al, ScriptaMaterialia 67 (20.12) 590-593) and from about 280 K. to 320 in the case of M As^Sb, (H. Wcu!a, Y. Tan be, Appl. Phys. Lett. 2001, 79, 3302). These temperature ranges are considered suitable for a variety of different applications including hyperthermia therapy, for example..

[0063] A heating system configured to provide hyperthermia therapy according to an embodiment of the present disclosure is illustrated in Figs. 8a and 8b. The heating system includes ferromagnetic material 1 exhibiting a first-order magnetic transition and. having a Curie temperature of between 40 and 50°C, the ferromagnetic material being provided in nanoparticulate .forrn. Referring t Fig. 8a, the nanoparticles 1 are injected using a syringe 6 into a cancerous tumour 2 of a subject 3. Subsequently, and with reference to Fig. 8b, a magnetic field generator 4 is arranged t apply an alternating magnetic field 5 from a remote location to the ferromagnetic material inside the tumour 2, causing apoptosis of the cancerous cells.

[0064] A heating system according to another embodiment of the present disclosure is illustrated in Figs. 9a and 9b. The heating system includes ferromagnetic material 10 exhibiting a first-order magnetic transition and having a Curie temperature of between 40 and 50°C, the ferromagnetic material being provided in the form of aft implant. Referring to Fig. 9a, the ferromagnetic implant 10 is surgically implanted into a cancerous tumour 20 of a subject 30. Subsequently, referring to Fig. 9b, a magnetic field generator 40 is arranged to apply an alternating magnetic field 50 from a remote location to the ferromagnetic material inside th tumour 20, causing apoptosis of the cancerous cells.

[0065] In alternative- embodiments, the feiTomagnetic material may be employed for remote heating in other technologies. In a heat assisted forward osmosis water desalination process, for example, magnetic field-induced heating can be used to recover water from swollen hydrogel draw agents. In Razmjou et at. (Environ. Sci, TecbnoL 2013, 47, 6297-6305) fast deswelling of polymer hydrogel particles was achieved by incorporating magnetic- y-Fe2<¾ nanoparticles exhibiting a second-order magnetic transition. The technique described in Razmjou et al., which is incorporated by reference herein, m y be further enhanced through, use of ferromagnetic materials exhibiting a First-order transition as disclosed herein,

[0066] It will be appreciated by persons skilled in the art that numerous variations and or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as Illustrative and not .restrictive..