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This study investigates the microwave ignition behavior of a range of thermites of aluminum, boron, titanium, and tantalum fuels with oxides of Bi2O3, CuO, and Fe2O3. In order to gain insight into the modes of energy transfer leading to ignition, thermites are heated in either a purely electric or magnetic field environment within a single‐mode 2.45 GHz resonant cavity with electric field strengths of 40 to 110 kV/m and magnetic field strengths of 22 to 258 A/m. Thermite stoichiometry is varied as well as particle size and thermite mass. The shortest ignition delays in electric and magnetic fields were found to be 1.37 s (nAl and CuO) and 0.87 s (nAl and CuO), respectively. The use of a variety of carbon susceptors to shorten ignition delay is also studied. Carbon susceptors are found to appreciably shorten ignition delays to as short as 140 and 170 ms for the E and B field respectively (nAl and CuO with multiwalled carbon nanotubes). The results of this work are informative on thermite component choice and the preferred mechanism (electric vs magnetic field) of heating for various thermite compositions for consideration of the increasingly popular ignition via electromagnetic fields. [ABSTRACT FROM AUTHOR]

Cancer treatment remains a pressing global challenge, with magnetic hyperthermia emerging as a promising alternative approach. The article explores the potential of pure and doped magnetite nanoparticles for hyperthermia-based cancer treatment, aiming to enhance therapeutic efficacy while minimizing side effects. Key findings include the synthesis and characterization of NPs—Fe3O4, SnFe2O4, and CoFe2O4—using co-precipitation methods, with emphasis on their size, morphology, magnetic, structural and thermal properties confirmed through techniques like SEM, EDX, VSM, XRD and TGA. The nanoparticles' hyperthermic effects were assessed through infrared imaging, showing CoFe2O4 NPs induced the highest heating efficiency as compared to Fe3O4 and SnFe2O4 NPs. Importantly, all nanoparticles showed negligible hemolysis at a concentration of 0.2 mg/ml, indicating their compatibility with human blood. This study contributes valuable insights into optimizing MNP-based hyperthermia treatments, aiming for safer and more effective cancer therapies in the future. SnFe2O4 NPs haven't been extensively explored in the context of hyperthermia applications, making it a unique contribution to the field. The research employs an innovative and cost-effective method for evaluating the hyperthermic effect of nanoparticles using an infrared camera. This approach overcomes the potential limitations associated with probe-based temperature measurement, offering a more accurate assessment of nanoparticle-induced hyperthermia. The research thoroughly compares its findings with existing literature, highlighting the novelty of the achieved results in terms of maximum hyperthermia with minimal frequency and magnetic field strength without inducing toxicity in human blood. [ABSTRACT FROM AUTHOR]

Direct air capture (DAC) is a promising technology for decarbonization through the removal of CO2 from the atmosphere. In many DAC processes, the regeneration energy used to restore the capture capacity of sorbents accounts for a significant fraction of the energy required by the whole process. Here we report an effective and scalable sorbent regeneration method for liquid DAC solvents based on magnetic nanoparticles (MNPs) heating with AC magnetic fields. MNPs can be directly heated to provide uniform and rapid volumetric heating, as we demonstrate by promoting the release of captured CO2 from an aqueous solution of potassium sarcosinate. Our results showed that 90% of the solvent can be regenerated within 7.5 min of heating through proposed technique. The MNPs and solvent are found to be stable during the regeneration process and the MNPs showed long‐term stability in the CO2‐saturated solvent. Cyclic experiments showed that the nanoparticles can be reused for multiple cycles without performance deterioration. The process is operated in a noncontact mode through electromagnetic waves, making it an adoptable approach for existing carbon capture systems. The MNPs heating provides an effective regeneration strategy for liquid solvents used in carbon capture processes, in particular for DAC. [ABSTRACT FROM AUTHOR]

Magnetic Field Hyperthermia is a technique where tumours are treated through an increase in local temperature upon exposure to alternating magnetic fields (AMFs) that are mediated by magnetic nano-particles (MNPs). In an AMF, these particles heat-up and kill the cells. The relationship between an AMF and the heating-rate is complex, leading to confusion when comparing data for different MNP and AMF conditions. This work allows for the thermal-response to be monitored at multiple AMF amplitudes while keeping other parameters constant. An induction-heating coil was designed based on a Zero-Voltage-Zero-Current (ZVZC) resonant circuit. The coil operates at 93 kHz with a variable DC drive-voltage (12–30 V). NEC4 software was used to model the magnetic field distribution, and MNPs were synthesised by the coprecipitation method. The magnetic field was found to be uniform at the centre of the coil and ranged from 1 kAm−1 to 12 kAm−1, depending on the DC drive-voltage. The MNPs were found to have a specific absorption rate (SAR) of 1.37 Wg−1[Fe] and 6.13 Wg−1[Fe] at 93 kHz and 2.1 kAm−1 and 12.6 kAm−1, respectively. The measured SAR value was found to be directly proportional to the product of the frequency and field-strength (SARα f Ho). This leads to the recommendation that, when comparing data from various groups, the SAR value should be normalized following this relationship and not using the more common relationship based on the square of the field intensity (SARα f Ho2). [ABSTRACT FROM AUTHOR]

The improper treatment of crude oil will cause great harm to the ecological environment and biological health. Traditional oil spill clean-up methods have problems such as high cost and secondary pollution. Thermal-assisted oil absorption material can achieve rapid adsorption of high-viscosity crude oil. The design strategies of thermally assisted oil absorption materials were summarized, including improving hydrophobicity/lipophilicity, enhancing capillary force and increasing thermal effect (Joule heating, photothermal conversion, magnetic heating). The oil absorption mechanism was elaborated from three aspects, namely, heat conversion, heat transfer and oil spill adsorption mechanism. The materials are mainly commercialized sponges and aerogels as carriers to recover crude oil through distillation, extrusion, pumping, etc. Among the four types of thermally assisted oil absorption materials: Joule-heating type needs rapidly raise the temperature at a small voltage to improve safety; there are obvious limitations in solar-type, such as slow warming rate, limited heating uniformity, and highly susceptible to the influence of meteorological conditions; magnetic-heating type is less studied and has challenges in practical application; the combination of solar-assisted and Joule-heating-assisted is common in the composite type. The thermal responsiveness, reusability and recyclability of thermally assisted oil absorption materials need to improve in the future. [ABSTRACT FROM AUTHOR]

Using magnetic nanoparticles for extracorporeal magnetic heating applications in bio-medical technology allows higher external field amplitudes and thereby the utilization of particles with higher coercivities (HC). In this study, we report the synthesis and characterization of high coercivity cobalt ferrite nanoparticles following a wet co-precipitation method. Particles are characterized with magnetometry, X-ray diffraction, Mössbauer spectroscopy, transmission electron microscopy (TEM) and calorimetric measurements for the determination of their specific absorption rate (SAR). In the first series, CoxFe3−xO4 particles were synthesized with x = 1 and a structured variation of synthesis conditions, including those of the used atmosphere (O2 or N2). In the second series, particles with x = 0 to 1 were synthesized to study the influence of the cobalt fraction on the resulting magnetic and structural properties. Crystallite sizes of the resulting particles ranged between 10 and 18 nm, while maximum coercivities at room temperatures of 60 kA/m for synthesis with O2 and 37 kA/m for N2 were reached. Magnetization values at room temperature and 2 T (MRT,2T) up to 60 Am2/kg under N2 for x = 1 can be achieved. Synthesis parameters that lead to the formation of an additional phase when they exceed specific thresholds have been identified. Based on XRD findings, the direct correlation between high-field magnetization, the fraction of this antiferromagnetic byphase and the estimated transition temperature of this byphase, extracted from the Mössbauer spectroscopy series, we were able to attribute this contribution to akageneite. When varying the cobalt fraction x, a non-monotonous correlation of HC and x was found, with a linear increase of HC up to x = 0.8 and a decrease for x > 0.8, while magnetometry and in-field Mössbauer experiments demonstrated a moderate degree of spin canting for all x, yielding high magnetization. SAR values up to 480 W/g (@290 kHz, 69 mT) were measured for immobilized particles with x = 0.3, whit the external field amplitude being the limiting factor due to the high coercivities of our particles. [ABSTRACT FROM AUTHOR]

Stable aqueous suspension of magnetic nanoparticles is essential for effective magnetic hyperthermia and other applications of magnetic heating in an alternating magnetic field. However, the alternating magnetic field causes strong agglomeration of magnetic nanoparticles, and this can lead to undesirable phenomena that deteriorate the bulk magnetic properties of the material. It has been shown how this magnetic field influences the distribution of magnetic agglomerates in the suspension. When investigating the influence of the sonication treatment on magnetic colloids, it turned out that the hydrodynamic diameter as a function of sonication time appeared to have a power-law character. The effect of magnetic colloid ageing on magnetic heating was discussed as well. It was shown how properly applied ultrasonic treatment could significantly improve the stability of the colloid of magnetic nanoparticles, ultimately leading to an increase in heating efficiency. The optimal sonication time for the preparation of the magnetic suspension turned out to be time-limited, and increasing it did not improve the stability of the colloid. The obtained results are important for the development of new materials where magnetic colloids are used and in biomedical applications. [ABSTRACT FROM AUTHOR]

A self-contained nanocapsule for nonspecific cytotoxic anticancer drug delivery and release activated by an enzyme and an alternating magnetic field (AMF) is introduced. This specific prodrug-like drug delivery platform is based on an esterase, an oligomer-based separating barrier, and an ester-linked anticancer peptide melittin encapsulated together in the enlarged pore spaces of the mesoporous silica nanoparticles. A superparamagnetic iron oxide nanoparticle core embedded in the center acts as a nanoheater to stimulate a cascade drug release. Each pore space was designed as a reaction nanovial for the activation of the drug release when the solution inside the nanovial is heated. By employing a thermoresponsive separating barrier as a shield of the peptide drug as well as a separator between the ester-containing peptides and the esterase, the nonspecific cytotoxic effect of the drug and off-target drug release are avoided because the drugs remain inactive in the absence of AMF stimulation. When AMF heating actuates the removal of the separating barrier and exposes the peptide drugs to the enzymes, drug release can be activated. In vivo antitumor experiments further revealed that the nanocapsules exhibited excellent biocompatibility and high tumor-targeting/inhibiting efficiency. The selected esterase, which is in close proximity to the ester-containing peptide drug, efficiently cleaves the ester bonds, thereby causing a catalytic release of peptide drugs and intensified anticancer efficacy. [ABSTRACT FROM AUTHOR]

Magnetic heating by nanoparticles has recently been successfully employed in heterogeneous catalysis. In such processes, the maximum temperature that can be reached depends on the Curie temperature (Tc) of the heating material. Here, in order to extend the range of accessible temperatures and consequently the range of possible reactions, to those requiring high temperatures, we developed and fully characterized a series of FeCo nanoparticles containing different concentrations of cobalt, in order to tune their magnetic properties and Tc. Their efficiency is compared to that of iron carbide nanoparticles, which display a lower Tc. Specific absorption rate (SAR) measurements as a function of temperature, performed using a homemade pyrometer-based setup, clearly show that although the heating power of iron carbide nanoparticles is higher at room temperature it decreases more rapidly with temperature than that of iron cobalt nanoparticles, in agreement with their lower Tc. In a showcase, Fe0.5Co0.5 nanoparticles allow, in addition to CO2 hydrogenation, dry reforming of propane and methane, and dehydrogenation of propane, these reactions requiring temperatures of 350 °C, 600 °C, and 700 °C, respectively. Furthermore, the use of Fe0.5Co0.5 nanoparticles is less energy demanding, as it allows carrying out CO2 hydrogenation at lower magnetic fields and at frequencies as low as 100 kHz. Dry reforming of methane and propane were carried out in the presence of a Ni nanoparticle-based catalyst, whereas dehydrogenation of propane required as a catalyst PtSn nanoparticles synthesized through an organometallic route. Fe0.5Co0.5 nanoparticles can therefore be used as universal heating agents allowing reactions to be performed up to ca. 700 °C upon association with the appropriate catalyst. [ABSTRACT FROM AUTHOR]

Purpose: Technologies with low environmental impacts and promoting renewable energy sources are required to meet the energetic demand while facing the increase of gas emissions associated to the greenhouse effect and the depletion of fossil fuels. CO2 methanation activated by magnetic heating has recently been reported as a highly efficient and innovative power-to-gas technology in a perspective of successful renewable energy storage and carbon dioxide valorisation. In this work, the life cycle assessment (LCA) of this process is performed, in order to highlight the environmental potential of the technology, and its competitivity with in respect to conventional heating technologies. Methods: The IMPACT 2002+ was used for this LCA. The process studied integrates methanation, water electrolysis and CO2 capture and separation. This "cradle-to-gate" LCA study does not consider the use of methane, which is the reaction product. The functional unit used is the energy content of the produced CH4. The LCA was carried out using the energy mix data for the years 2020 and 2050 as given by the French Agency for Environment and Energy management (ADEME). Consumption data were either collected from literature or obtained from the LPCNO measurements as discussed by Marbaix (2019). The environmental impact of the CO2 methanation activated by magnetic heating was compared with the environmental impact of a power-to-gas plant using conventional heating (Helmeth) and considering the environmental impact of the natural gas extraction. Results: It is shown that the total flow rate of reactants, the source of CO2 and the energy mix play a major role on the environmental impact of sustainable CH4 production, whereas the lifetime of the considered catalyst has no significant influence. As a result of the possible improvements on the above-mentioned parameters, the whole process is expected to reduce by 75% in its environmental impact toward 2050. This illustrates the high environmental potential of the methanation activated by magnetic heating when coupled with industrial exhausts and renewable electricity production. Conclusions: The technology is expected to be environmentally competitive compared with existing similar processes using external heating sources with the additional interest of being extremely dynamic in response, in line with the intermittency of renewable energy production. [ABSTRACT FROM AUTHOR]

The EnovHeat project aims at developing an innovative heat pump system based on the magnetocaloric effect and active magnetic regenerator technology to provide for the heating needs of a single family house in Denmark. Unlike vapor-compression devices, magnetocaloric heat pumps use the reversible magnetocaloric effect of a solid refrigerant to build a cooling/heating cycle. It has the potential for high coefficient of performance, more silent operation and efficient part-load control. After presenting the operation principles of the magnetocaloric device and the different models used in the current numerical study, this article demonstrates for the first time the possibility to utilize this novel heat pump in a building. This device can be integrated in a single hydronic loop including a ground source heat exchanger and a radiant under-floor heating system. At maximum capacity, this magnetocaloric heat pump can deliver 2600 W of heating power with an appreciable average seasonal system COP of 3.93. On variable part-load operation with a simple fluid flow controller, it can heat up an entire house with an average seasonal system COP of 1.84. [ABSTRACT FROM AUTHOR]

Whereas the application of optically or magnetically heated nanoparticles to destroy tumours is now well established, the extension of this concept to target pathogens has barely begun. Here we examine the challenge of targeting pathogens by this means and, in particular, explore the issues of power density and heat transfer. Depending on the rate of heating, either hyperthermia or thermoablation may occur. This division of the field is fundamental and implies very different sources of excitation and heat transfer for the two modes, and different strategies for their clinical application. Heating by isolated nanoparticles and by agglomerates of nanoparticles is compared: hyperthermia is much more readily achieved with agglomerates and for large target volumes, a factor which favours magnetic excitation and moderate power densities. In contrast, destruction of planktonic pathogens is best achieved by localised thermoablation and very high power density, a scenario that is best delivered by pulsed optical excitation. [ABSTRACT FROM AUTHOR]

Microwave heating is rapidly emerging as an effective and efficient tool in various technological and scientific fields. A comprehensive understanding of the fundamentals of microwave-matter interactions is the precondition for better utilization of microwave technology. However, microwave heating is usually only known as dielectric heating, and the contribution of the magnetic field component of microwaves is often ignored, which, in fact, contributes greatly to microwave heating of some aqueous electrolyte solutions, magnetic dielectric materials and certain conductive powder materials, etc. This paper focuses on this point and presents a careful review of microwave heating mechanisms in a comprehensive manner. Moreover, in addition to the acknowledged conventional microwave heating mechanisms, the special interaction mechanisms between microwave and metal-based materials are attracting increasing interest for a variety of metallurgical, plasma and discharge applications, and therefore are reviewed particularly regarding the aspects of the reflection, heating and discharge effects. Finally, several distinct strategies to improve microwave energy utilization efficiencies are proposed and discussed with the aim of tackling the energy-efficiency-related issues arising from the application of microwave heating. This work can present a strategic guideline for the developed understanding and utilization of the microwave heating technology. [ABSTRACT FROM AUTHOR]

Heat can be induced within a tissue enriched with magnetic nanoparticles by exposing it to an alternating magnetic field. In this paper we examine the evaluation of the heat distribution and therefore the temperature development around such a heat source which can be suitable for magnetic heating treatment. We study the heat transfer from tissue enriched with magnetic nanoparticles to regions of no or minor enrichment of nanoparticles, particularly. The evaluation of the temperature distribution took place with the help of a tissue phantom. The phantom is composed of two concentric cylinders. The inner cylinder consists of a defined mixture of polyurethane gel and magnetic fluid. This cylinder represents tissue enriched with nanoparticles. The outer cylinder, which stands for pure tissue consists of polyurethane only. This tissue phantom has been exposed to an alternating magnetic field according to the protocol of the magnetic heating treatment. The temperature measurements were performed by thermocouples which are placed on defined positions. The experimentally obtained temperature data is the basis for a finite element method (FEM) simulation model. The FEM model allows the determination of heat transition from regions enriched with magnetic nanoparticles to regions with no or minor nanoparticle accumulation. [ABSTRACT FROM AUTHOR]

Bio-compatible magnetic fluids having high saturation magnetization find immense applications in various biomedical fields. Aqueous ferrofluids of superparamagnetic iron oxide nanoparticles with narrow size distribution, high shelf life and good stability is realized by controlled chemical co-precipitation process. The crystal structure is verified by X-ray diffraction technique. Particle sizes are evaluated by employing Transmission electron microscopy. Room temperature and low-temperature magnetic measurements were carried out with Superconducting Quantum Interference Device. The fluid exhibits good magnetic response even at very high dilution (6.28 mg/cc). This is an advantage for biomedical applications, since only a small amount of iron is to be metabolised by body organs. Magnetic field induced transmission measurements carried out at photon energy of diode laser (670 nm) exhibited excellent linear dichroism. Based on the structural and magnetic measurements, the power loss for the magnetic nanoparticles under study is evaluated over a range of radiofrequencies. [ABSTRACT FROM AUTHOR]

More than 20 years ago, it was hypothesized that intracellular hyperthermia is superior to extracellular hyperthermia. It was further hypothesized that even a single biological cell containing magnetic nanoparticles can be treated for hyperthermia by an AC magnetic field, independent of its surrounding cells. Since experimental investigation of the thermal effects of intracellular hyperthermia is not feasible, these hypotheses have been studied theoretically. The current report shows that nano-scale heating effects are negligible. This study further shows that intracellular heat generation is sufficient to create the necessary conditions for hyperthermia only in a large group of cells loaded with nanoparticles, having an overall diameter of at least 1mm. It is argued in this report that there is no reason to believe that intracellular hyperthermia is superior to extracellular hyperthermia in the thermal sense. [ABSTRACT FROM AUTHOR]

Herein, we have synthesized citric acid functionalized monodisperse (6–12 nm) octahedral-shaped Fe3O4 nanoparticles (NPs). The as-prepared octahedral-shaped Fe3O4 NPs exhibit a bulk-like magnetization ( \sim 92 emu/g) value due to lesser surface spin disorder. In addition, compared with spherical morphology, these octahedral NPs (Oct-NPs) exhibit much higher specific absorption rate (SAR) value as a potential candidate for hyperthermia treatment and higher R_{2} value as an efficient contrast agent for magnetic resonance imaging. The enhanced R_{2} relaxivity and SAR values are attributed to the higher saturation magnetization ( MS ) value and a larger surface area of Oct-NPs. The R2 value of 12 nm-sized Oct-NPs suspension is 353 ${{\rm {mM}}^{-1}}{{\rm {s}}^{-1}} , which is 3.5 times higher than that of the commercial contrast agent. With increase in size (6–12 nm), the R2 value gradually increases from 198 to 353 {{mM}^{-1}}{{{s}}^{-1}} ; this increase is a consequence of the MS enhancement as well as the surface area. [ABSTRACT FROM AUTHOR]

The increasing use of magnetic nanoparticles as heating agents in biomedicine is driven by their proven utility in hyperthermia therapeutic treatments and heat-triggered drug delivery methods. The growing demand of efficient and versatile nanoheaters has prompted the creation of novel types of magnetic nanoparticle systems exploiting the magnetic interaction (exchange or dipolar in nature) between two or more constituent magnetic elements (magnetic phases, primary nanoparticles) to enhance and tune the heating power. This process occurred in parallel with the progress in the methods for the chemical synthesis of nanostructures and in the comprehension of magnetic phenomena at the nanoscale. Therefore, complex magnetic architectures have been realized that we classify as: (a) core/shell nanoparticles; (b) multicore nanoparticles; (c) linear aggregates; (d) hybrid systems; (e) mixed nanoparticle systems. After a general introduction to the magnetic heating phenomenology, we illustrate the different classes of nanoparticle systems and the strategic novelty they represent. We review some of the research works that have significantly contributed to clarify the relationship between the compositional and structural properties, as determined by the synthetic process, the magnetic properties and the heating mechanism. [ABSTRACT FROM AUTHOR]

The study investigated the phenomenon of the fast aggregation of single-domain magnetic iron oxide nanoparticles in stable aqueous colloidal suspensions due to the presence of a radio-frequency (RF) magnetic field. Single-domain nanoparticles have specific magnetic properties, especially the unique property of absorbing the energy of such a field and releasing it in the form of heat. The localized heating causes the colloid to become unstable, leading to faster agglomeration of nanoparticles and, consequently, to rapid sedimentation. It has been shown that the destabilization of a stable magnetic nanoparticle colloid by the RF magnetic field can be used for the controlled filtration of larger agglomerates of the colloid solution. Two particular cases of stable colloidal suspensions were considered: a suspension of the bare nanoparticles in an alkaline solution and the silica-stabilized nanoparticles in a neutral solution. The obtained results are important primarily for biomedical applications and wastewater treatment. [ABSTRACT FROM AUTHOR]

Magnetic inductive heating (MIH) has been a topic of great interest because of its potential applications, especially in biomedicine. In this paper, the parameters characteristic for magnetic inductive heating power including maximum specific loss power (SLPmax), optimal nanoparticle diameter (Dc) and its width (ΔDc) are considered as being dependent on magnetic nanoparticle anisotropy (K). The calculated results suggest 3 different Néel-domination (N), overlapped Néel/Brownian (NB), and Brownian-domination (B) regions. The transition from NB- to B-region changes abruptly around critical anisotropy Kc. For magnetic nanoparticles with low K (K < Kc), the feature of SLP peaks is determined by a high value of Dc and small ΔDc while those of the high K (K > Kc) are opposite. The decreases of the SLPmax when increasing polydispersity and viscosity are characterized by different rates of d(SLPmax)/dσ and d(SLPmax)/dη depending on each domination region. The critical anisotropy Kc varies with the frequency of an alternating magnetic field. A possibility to improve heating power via increasing anisotropy is analyzed and deduced for Fe3O4 magnetic nanoparticles. For MIH application, the monodispersity requirement for magnetic nanoparticles in the B-region is less stringent, while materials in the N- and/or NB-regions are much more favorable in high viscous media. Experimental results on viscosity dependence of SLP for CoFe2O4 and MnFe2O4 ferrofluids are in good agreement with the calculations. These results indicated that magnetic nanoparticles in the N- and/or NB-regions are in general better for application in elevated viscosity media. [ABSTRACT FROM AUTHOR]

Pickering emulsions (particle-stabilized emulsions) are usually considered because of their unique properties compared to surfactant-stabilized emulsions including better stability against emulsion aging. However, the interesting feature of particle-stabilized emulsions could be revealed during their magnetic heating. When magnetic particles constitute a shell around droplets and the sample is placed in an alternating magnetic field, a temperature increase appears due to energy dissipation from magnetic relaxation and hysteresis within magnetic particles. We hypothesize that the solidity of the magnetic particle shell around droplets can influence the process of heat transfer from inside the droplet to the surrounding medium. In this way, particle-stabilized emulsions can be considered as materials with changeable heat transfer. We investigated macroscopically heating and cooling of oil-in-oil magnetic Pickering emulsions with merely packed particle layers and these with a stable particle shell. The change in stability of the shell was obtained here by using the coalescence of droplets under the electric field. The results from calorimetric measurements show that the presence of a stable particle shell caused a slower temperature decrease in samples, especially for lower intensities of the magnetic field. The retarded heat transfer from magnetic Pickering droplets can be utilized in further potential applications where delayed heat transfer is desirable. [ABSTRACT FROM AUTHOR]

The present study explores the entropy generation, flow, and heat transfer characteristics of a dissipative nanofluid in the presence of transpiration effects at the boundary. The non-isothermal boundary conditions are taken into consideration to guarantee self-similar solutions. The electrically conducting nanofluid flow is influenced by a magnetic field of constant strength. The ultrafine particles (nanoparticles of Fe 3 O 4 / CuO ) are dispersed in the technological fluid water ( H 2 O ). Both the base fluid and the nanofluid have the same bulk velocity and are assumed to be in thermal equilibrium. Tiwari and Dass's idea is used for the mathematical modeling of the problem. Furthermore, the ultrafine particles are supposed to be spherical, and Maxwell Garnett's model is used for the effective thermal conductivity of the nanofluid. Closed-form solutions are derived for boundary layer momentum and energy equations. These solutions are then utilized to access the entropy generation and the irreversibility parameter. The relative importance of different sources of entropy generation in the boundary layer is discussed through various graphs. The effects of space free physical parameters such as mass suction parameter (S) , viscous dissipation parameter (E c) , magnetic heating parameter (M) , and solid volume fraction (ϕ) of the ultrafine particles on the velocity, Bejan number, temperature, and entropy generation are elaborated through various graphs. It is found that the parabolic wall temperature facilitates similarity transformations so that self-similar equations can be achieved in the presence of viscous dissipation. It is observed that the entropy generation number is an increasing function of the Eckert number and solid volume fraction. The entropy production rate in the Fe 3 O 4 − H 2 O nanofluid is higher than that in the CuO − H 2 O nanofluid under the same circumstances. [ABSTRACT FROM AUTHOR]

Utilization of magnetic nanoparticle-mediated conversion of electromagnetic energy into heat is gaining attention in catalysis as a source of heat needed for a substrate's chemical reaction (electrification of chemical conversions). We demonstrate that rapid and selective heating of magnetic nanoparticles opens a way to the rapid synthesis of a nanocatalyst. Magnetic heating caused rapid reduction of Ru3+ cations in the vicinity of the support material and enabled preparation of a Ru nanoparticle-bearing nanocatalyst. Comparative synthesis conducted under conventional heating revealed significantly faster Ru3+ reduction under magnetic heating. The faster kinetic was ascribed to the higher surface temperature of the support material caused by rapid magnetic heating. The nanocatalyst was rigorously tested in the hydrotreatment of furfural. The activity, selectivity and stability for furfural hydrogenation to furfuryl alcohol, a valuable biobased monomer, remained high even after four magnetic recycles. [ABSTRACT FROM AUTHOR]