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Electromagnetic vibration and noise of driving motor affect the comfort for electric vehicles. Considering low harmonic component and pole design flexibility of double-layer interior permanent magnet (IPM) machines, in this paper, an improved analytical method of no-load air gap flux density for double-layer IPM machines is introduced, and the harmonic spectrum of electromagnetic force is analyzed. A commercial double-layer IPM machine is taken as benchmark, the electromagnetic–structure–sound coupling model is established. The main spatial and temporal order of electromagnetic force for benchmark motor is indicated. Based on this analytical model, a method to minimize the electromagnetic force of specific harmonic component is proposed to reduce electromagnetic vibration and noise, by optimizing parameters of double-layer IPM machine rotor pole without impairing the motor performance. The vibration and noise of the optimized motor under working condition and no-load are compared with the results of the benchmark motor by multi-physics simulation, and validate the proposed optimization approach.

We investigated the magnetic properties, corrosion resistance, and microstructure of Tb6Fe13Cu-added Nd–Fe–B sintered magnets through the magnetic measurement device, electrochemical method, and microstructure analysis. The results show that doping Tb6Fe13Cu can not only effectively improve the intrinsic coercivity but also significantly improve the corrosion resistance of the magnet. An intrinsic coercivity from 15.01 to 21.40 kOe is achieved in magnet by increasing the additive amounts of Tb6Fe13Cu to 3 wt%, while the remanence and the maximum energy product decreased slightly. It was also found that as the amount of addition increases, the corrosion potential of the magnet gradually becomes positive. Further investigations reveal that the remarkable enhancement in coercivity and corrosion resistance was owing to the formation of a Tb-rich (Nd, Pr, Tb)2Fe14B shell structure, the optimization in distribution/morphology of intergranular phases, and the more stable RE-rich phase.

Fine, uniform and equiaxed grain structure is one of the most striking features of high-quality Al targets. In general, the imposition of magnetic stirring on the liquid Al during the solidification process is an effective method to promote grain refinement. In the present study, a self–made rotating system of permanent magnets is reported to stir liquid Al during solidification. The temperature change and grain structure of pure Al subjected to a permanent magnet stirring (PMS) are analyzed. The experimental results reveal that the forced convection driven by PMS can lead to a more homogeneous temperature field in the melt. Meanwhile, PMS can greatly refine the grain structure of pure Al and eliminate cavities, but it may induce more gas holes in the ingots. Moreover, a fresh intermittent permanent magnet stirring (I-PMS) approach has been proposed and successfully applied to realize grain refinement of pure Al. Some casting problems can be perfectly solved using suitable processing parameters. Through some valuable experimental works, systematic researches on grain refinement of pure Al under PMS are performed to better understand its refining mechanisms. Therefore, this article further enhances our understanding of related fields and fills the research blank.

In order to ensure the continuous output of electric energy, it is necessary to study the fault-tolerant operation of permanent magnet wind generator with double three-phase winding under partial winding fault. For a permanent magnet wind generator with double three-phase winding, after one of the windings is isolated due to fault, the winding distribution will have a certain effect on the generator’s output power and electromagnetic torque during derating operation. In order to find the maximum power output and electromagnetic torque output under this condition, the permanent magnet wind generator with double three-phase winding is studied in this research. A 60 kW double three-phase winding generator with 12 parallel branches is designed. By combining the parallel branches of the generator in different parallel ways, four different double three-phase winding schemes are obtained and the corresponding physical models under single winding conditions are established, simulated and analyzed, and the optimal simulation results of the four schemes are obtained. Finally, through the construction and testing of the prototype platform, the accuracy of the theoretical analysis and simulation results is verified. The results show that the permanent magnet wind generator with double three-phase winding can obtain the maximum power output and electromagnetic torque through the optimal winding combination under single winding operation, which will increase the economic benefit of the generator and sustainable utilization of wind energy.

Background Recent case reports and small studies have reported activation of the magnet-sensitive switches in cardiovascular implantable electronic devices (CIED) by the new iPhone 12 series, initiating asynchronous pacing in pacemakers and suspension of anti-tachycardia therapies in ICDs. Objective and Methods We performed a prospective single-center observational study to quantify the risk of magnetic field interactions of the iPhone 12 with CIEDs. A representative model of each CIED series from all manufacturers was tested ex vivo. Incidence and minimum distance necessary for magnet mode triggering were analyzed in 164 CIED patients with either the front or the back of the phone facing the device. The magnetic field of the iPhone 12 was analyzed using a 3-axis hall probe. Results Ex vivo, magnetic interferences occurred in 84.6% with the back compared to 46.2% with the front of the iPhone 12 facing the CIED. In vivo, activation of the magnet-sensitive switch occurred in 30 CIED patients (18.3%; 21 pacemaker, 9 ICDs) when the iPhone 12 was placed in close proximity over the CIED pocket and the back of the phone was facing the skin. Multiple binary logistic regression analysis identified the implantation depth (95% confidence interval [CI], 0.02 to 0.24) as independent predictor of magnet-sensitive switch activation. Conclusion Magnetic field interactions occur only in close proximity, and with precise alignment of the iPhone 12 and CIEDs. It is important to advise CIED patients to not put the iPhone 12 directly on the skin above the CIED. Further recommendations are not necessary.

Flux-weakening control strategy of interior permanent magnet synchronous machines have a massive significance to enlarge the operational speed of electric vehicles (EVs) and to facilitate the power integration. However, how to keep the torque stability and achieve the fast response should be given the top priority. In order to facilitate the flux-weakening control application on EVs, a novel flux-weakening control strategy with fast transient current response is proposed. In detail, the change of dynamic voltage margin and its response are analyzed in this paper. Accordingly, the flux-weakening control is proposed through the collaborative control of the dynamic current compensation and the d-axis current-error adjustment. To fully evaluate effectiveness of proposed strategy, the traditional PI-based voltage-closed flux-weakening and the low-pass-filter method are constructed for comparison. The simulation and experimental results illustrate that the proposed strategy can achieve the fast torque response and also have the capacity to reduce the torque fluctuation of the stable state.

A new technology, representing a complete process of recovery of rare earth elements from neodymium-iron-boron permanent magnets scrap by acid dissolution and liquid-liquid extraction, is proposed. This technology is based on basic research of individual process steps. A hydrometallurgical process containing acid leaching with subsequent two-step solvent extraction on a counter current multistage extraction column is employed to separate iron from lanthanides, re-extract lanthanides in the form of sulphates, precipitate as oxalates, and finally calcinate to a pure state as didymium oxide (praseodymium + neodymium) and dysprosium oxide.

This paper presents the design and analysis of electromagnetic characteristics of a five phase permanent magnet synchronous generator for direct drive wind energy conversion system (WECS). In this study, simple and accurate Dynamic Reluctance Network Modeling is used for design and optimization of generator. The anisotropic structure of stator and rotor for the accurate prediction of flux distribution in the air gap and electromagnetic performance is accounted by the dynamic variation of air gap reluctance in an electrical period. This model considers the leakage flux paths for machine design optimization to achieve better performance. In this context, three permanent magnet (PM) materials namely NdFeB, SmCo and ferrite are considered to evaluate the generated voltage. The dimensions of these permanent magnets are varied and performance under normal and saturated core condition is evaluated. A prototype is developed in the machine laboratory of the IIT(BHU) Varanasi (India) and results obtained in accordance with Finite Element Method.

With significant progress in the manufacturing of second-generation (2G) high temperature superconducting (HTS) tape, applications such as superconducting magnetic energy storage (SMES) have become promising for implementation in the electricity grid. Compared to Li-ion batteries, SMES can provide higher power levels at a lower capital cost (down to $200/kW), they have a longer lifetime (over 20 years) and a comparable cycle efficiency of over 95%. Nevertheless, SMES technology is still underdeveloped, which is reflected in the lack of large-scale 2G HTS SMES units. One of the main challenges is designing an optimal magnet that can persistently store energy while withstanding the forces arising from the magnetic field and maintaining a temperature below the critical transition value. This paper outlines a methodology of designing a 2G HTS SMES, using Yttrium-Barium-Copper-Oxide (YBCO) tapes operating at 22 K. The target storage capacity is set at 1 MJ, with a maximum output power of 100 kW. The magnet consists of a stack of double pancake coils designed for maximum storage capacity, using the minimum tape length. The properties of a commercial YBCO tape published in the literature are used to derive the equations for scaling the critical current with magnetic field intensity and direction, as well as operating temperature. The inductance of the resulting coil configuration is calculated analytically, and is used for estimating the total storage capacity of the magnet. Finally, the properties of the superconducting magnet are summarised in a table.

Herein, we report a biphase stratification strategy that enables the encapsulation of magnetic mesoporous TiO2 inside an ordered mesoporous C/SiO2 framework. The obtained composites exhibit high surface areas (up to 600 m2 g−1), large perpendicular pore sizes (up to 9 nm) and a strong magnetic response (∼10.0 emu g−1), presenting significantly enhanced degradation activities toward pentachlorophenol (PCP) and bisphenol-A (BPA) under acoustic cavitation energy. The remarkable performance is ascribed to the synergistic effect from the unique structural modulation: 1) The large ordered mesopores favors the mass transfer, 2) The mesoporous C/SiO2 frameworks promote the adsorption of organic pollutants and enrich them close to the TiO2 surface and 3) The special spatial arrangement of different components facilitates the generation of cavitation bubbles, leading to the increase in the overall hydroxyl-radical-production rate. Moreover, owing to the effective confinement, the as-prepared materials possess an excellent stability and durability. More importantly, the catalysts can easily be recovered by a magnet and show an excellent reusability. It is believed that these results could provide an important insight for the development of an efficient, stable and facile recoverable catalyst for the acoustic chemical process. Keywords: Fe3O4@mTiO2@mC/SiO2, Acoustic cavitation, Magnetic separation, Mechanical stability

A simple, facile and efficient method has been developed for the Friedel–Crafts benzoylation of arenes using magnetic γ-Fe2O3 nanoparticles under solvent-free sonication. The γ-Fe2O3 nanoparticles were used as an efficient and magnetically recoverable catalyst for the synthesis of aromatic ketones in good to excellent yields at room temperature under solvent-free. The reaction occurred with high regioselectivity under mild condition. The magnetic γ-Fe2O3 nanoparticles are economically synthesized in large-scale, easily separated from the reaction mixture by an external magnet and able to be reused several times without significant loss of the catalytic performance, which make them easy application to industrial processes. Keywords: Magnetic γ-Fe2O3 nanoparticles, Friedel–Crafts acylation, Solvent-free sonication, Green catalyst

Spherical rotors are a new paradigm in magic angle spinning (MAS) solid-state nuclear magnetic resonance (NMR). The simple geometry makes smaller diameter spheres and their utilization within narrow-bore NMR probes feasible. Here we report a 68 kHz spinning frequency of 2 mm diameter spheres using helium spinning gas outside the magnet and demonstrate the use of KMnO4 to adjust the magic angle at a spinning frequency of 59.3 kHz for MAS NMR. We observe third-order spinning sidebands in the 55Mn spectrum clearly showing the MAS frequency of 59.3 kHz, with KBr showing nearly no first-order spinning sidebands at a similar frequency. The spinning stability was ±0.5% during data acquisition without spinning regulation. To address concerns about the low NMR filling factor of MAS spheres, we employ a modified stator and a smaller coil and achieve three times higher NMR sensitivity then our previous coil geometries for MAS spheres. Advanced coil and rotor fabrication technologies are expected to further increase the spinning frequency and NMR sensitivity of MAS spheres.

In this paper, we extract the enormous soliton solutions from the (2 + 1)-dimensional Heisenberg ferromagnetic spin chain (HFSC) equation with the aid of enhanced ( G ′ / G )-expansion method in nonlinear dynamics of magnets. All soliton solutions represent as standings of hyperbolic function solution and trigonometric functions solution with arbitrary parameters. The nonlinear wave prearrangement is analyzed and showed in 3D, 2D, and contour plots with explicit estimations of the free parameters plotted in this literature. The enhanced ( G ′ / G )-expansion method is a suitable solution of nonlinear waves that improve the combination of magnetic models rises in the field of engineering as well.

Agredano-Torres, M., et al., A new spherical tokamak, the SMall Aspect Ratio Tokamak (SMART), is currently being designed at the University of Seville. The goal of the machine is to achieve a toroidal field of 1 T, a plasma current of 500 kA and a pulse length of 500 ms for a plasma with a major radius of 0.4 m and minor radius of 0.25 m. This contribution presents the design of the coils and power supplies of the machine. The design foresees a central solenoid, 12 toroidal field coils and 8 poloidal field coils. Taking the current waveforms for these set of coils as starting point, each of them has been designed to withstand the Joule heating during the tokamak operation time. An analytical thermal model is employed to obtain the cross sections of each coil and, finally, their dimensions and parameters. The design of flexible and modular power supplies, based on IGBTs and supercapacitors, is presented. The topologies and control strategy of the power supplies are explained, together with a model in MATLAB Simulink to simulate the power supplies performance, proving their feasibility before the construction of the system., This work received funding from the Fondo Europeo de Desarollo Regional (FEDER) by the European Commission under grant agreement numbers IE17-5670 and US-15570. Furthermore, it has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement no. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

The present work focuses on using a recently proposed method to create functionally graded adhesive joints using a polyurethane adhesive and iron microparticles. Functionally graded joints were created with the application of a suitable magnetic field in the centre of the overlap region. This field is able to move the iron microparticles and create a tailored particle distribution. The main goal of this work was to create a particle concentration gradient that changes from particle rich in the middle of the overlap to poor in the ends. Consequentially, the stiffness of the resulting composite is made to vary along the bondline. A numerical simulation was performed to determine the optimal distance between the magnet and the adhesive layer as well as the application time of the external magnetic field. In order to assess the influence of the iron particles on the adhesive, different particle amounts were experimentally considered and two particles distributions were evaluated (uniform and graded distributions). The predicted particles trajectories were validated through a study of the single lap joint (SLJ) fracture surfaces, showing that the magnetic particles follow the magnetic field lines towards the middle of the overlap. Also, by observing the same fracture surfaces, the recently proposed method was validated, a non-uniform particle distribution. Finally, SLJs containing 1% of iron microparticles with a graded distribution were found to exhibit the best mechanical performance. Thus, this method has been demonstrated to be a viable technique to enhance the mechanical properties of bonded joints, leading to a more uniform stress distribution along the bondline.

The novel contribution of this research is insight into the influence of different parameters in the magnet configurations on the load and stiffness of a ferrofluid pressure bearing. It is shown that magnets with a small cross-section magnetized alternatively up and downwards combine a high load capacity and moderate stiffness while being low on material cost and complexity. The configuration where magnets are placed alternatively in left and right direction magnetized inter spaced with iron yields the highest load capacity and stiffness, albeit at the cost of weight and complexity. It is shown that an increase in the number of magnets is beneficial for the stiffness in both magnetization configurations, as is an increase in remanent flux density of the magnet. A metal bottom plate made of iron reduces the necessary height of the magnet in the up-down magnetization configuration. The model was validated using a bearing pad arranged in the up-down configuration. The force-displacement curve of this pad was measured in a load frame, using the APG 513 ​A ferrofluid from Ferrotec. A load capacity of 1.75 ​N/cm2 was achieved, this exceeds previous pressure bearing implementations and performs comparable or better than implementations of single seal ferrofluid pocket bearings. These results show that the ferrofluid pressure bearing is a passive alternative in motion systems where the designer otherwise would have needed to use an active bearing.

Graphical abstract, Highlights • Permeant magnet motors are feasible to replace induction motors in Egypt. • Magnet demagnetization decreases efficiency, lifetime and feasibility of motors. • Despite partial demagnetization, utilization of PM motors in Egypt is feasible. • Feasibility of PM motors in Egypt is contingent on a 50% annual utilization. • Consideration of potential demagnetization is essential for estimating feasibility., Permanent magnet (PM) motors are rapidly replacing the dominant induction motors in industrial applications including pumps, fans, and compressors. PM motors are also gaining ground in critical sustainable energy applications such as wind systems, photovoltaic pumping systems and electric vehicles. Compared to induction motors, PM have higher efficiency. In this paper, the financial feasibility of replacing induction motors by PM motors at various operating conditions was analyzed on a preliminary basis. The impact of partial demagnetization and full loss of excitation on the feasibility of the replacement was also preliminarily investigated. It is found that the feasibility of replacement was less sensitive to reduction in the life time of PM motors than reduction in efficiency due to partial demagnetization. While detailed and lengthy studies are planned in the future, investigation outcomes suggest that the replacement remains feasible despite risks of demagnetization when utilization rates are above 50%. Details of the investigation are reported in the paper.

This data article reports the data for reflection and transmission coefficients of the SH0 and SH1 ultrasonic guided waves modes due to their interaction with tapered wall thinning in aluminium plates. Several thinning depths and edge taper angles were machined, at the total of 35 different samples. Periodic permanent magnet array electromagnet acoustic transducers were used to generate and receive the waves. Both modes were individually generated and separated in the received signal by means of effective post-processing technique. Reflection and transmission coefficients were calculated at both the leading and trailing edges of the thinning region for mode-converted and non-mode converted signals; therefore, eight coefficients were calculated for each generated mode, at the total of sixteen coefficients for each sample. Additional finite-element model was used in order to obtain numerical values for the coefficients. These data were used in order to analyze the interaction of the SH0 and SH1 modes with wall thinning and the capabilities of using them in non-destructive evaluation of corrosion-like defects in the research paper entitled “Interaction of SH guided waves with wall thinning” (Kubrusly et al., 2019).

The magnetoresistive properties of pinned spin valves (SV) and their roles in low-field sensing applications were characterized. The magnetoresistive parameters were extracted, including the exchange bias (Heb) field as a function of the iron content in the CoFe layer and the antiferromagnetic (AFM) thickness, the magnetoresistance (MR) ratio versus the spacer thickness, the coercivity (Hc) as a function of the seed layer, and the composite layer [NiFe/Co] used. These parameters are crucial in determining the features of the magnetic sensors. Eventually, the selected SV film structure of (Si/SiO2)/Ta(50 Å)/[NiFe(30 Å)/Co(15 Å)]/Cu(24 Å)/Co80Fe20(25 Å)/IrMn(100 Å)/Ta(50 Å) was found significant, and the SV elements were patterned using the lithographic lift-off method with the active cell dimensions of 2 μm × 150 μm. To define a pinning axis, a cool-field anneal was applied at 250 °C for 30 min in a magnetic field of 2 kOe. A Wheatstone half bridge was engineered using two SV elements and two external resistors. The operation point of the sensor was well tuned using a tiny permanent magnet. A sensitivity of 5 V/T was observed with a linear range of ±2 mT. To demonstrate the performance of the designed sensor, a measurement of the Earth magnetic field was carried out. The engineered SV sensor finds its usefulness in low-field magnetometer and electronic compass applications. Keywords: GMR, Giant magnetoresistance, Magnetic sensors, RF sputtering, Spin valve

Magnetic targeting is a cell delivery system using the magnetic labeling of cells and the magnetic field; it has been developed for minimally invasive cell transplantation. Cell transplantation with both minimal invasiveness and high efficacy on tissue repair can be achieved by this system. Magnetic targeting has been applied for the transplantation of bone marrow mesenchymal stem cells, blood CD133-positive cells, neural progenitor cells, and induced pluripotent stem cells, and for the regeneration of bone, cartilage, skeletal muscles, and the spinal cord. It enhances the accumulation and adhesion of locally injected cells, resulting in the improvement of tissue regeneration. It is a promising technique for minimally invasive and effective cell transplantation therapy. Keywords: Stem cell, Regeneration, Magnet, Cell delivery

Application of an external magnetic field during heat treatment affects the hardness of magnetic Fe-Cr-Co alloys. The microstructure and composition at atomic scale, as well as the hardening mechanisms need extensive studies. Using atomic resolution STEM, we investigated the effect of a 3 T magnetic field on the spinodal decomposition, as well as microstructure and hardness in step-aged Fe27wt. %Cr15wt. %Co samples. Spinodal decomposition resulted in a homogeneous α phase transforming into an Fe-Co rich α1 phase and a Cr rich α2 phase. Although α1 and α2 showed distinct contrast at low magnification Z-contrast images, close examination at atomic scale of the samples showed no sharp α1/α2 interfaces. Inside each phase, composition fluctuations occurred. A 3 T external magnetic field during step aging increased the size of the α1 phase and introduced microstructural anisotropy, which is desired for permanent magnet applications, In addition, the spinodal decomposition increased the hardness. Annealing in a 3 T magnetic field decreased the hardness but increased the ductility, which is desirable for manufacturing permanent magnets. The change in hardness values is attributed to the composition fluctuations of Fe, Cr and Co, and we further discuss the mechanisms for composition fluctuations and hardness.

Magnetic nanoparticles (NPs) in both individual and composite forms are substantial tools for catalytic purposes because they provide an extreme surface area through their nanoscale diameter. Recently, this species of nanomaterials has attracted much attentions in catalysis of the organic and inorganic reactions because the separation and purification processes can be easily performed by applying them. In addition, they can be recycled and reused for several successive cycles, which is a considerable advantage. Briefly, after completion of the synthetic reactions, the magnetic particles can be collected by holding an external magnet at the bottom of the flask, and the purification process is carried out by decanting of the rest mixture. The collected particles can be dried, reactivated, and reused if they are physically stable enough. In this chapter we will highlight the advantages of the use of the magnetic NPs in hybrid forms, which have recently been utilized in catalytic applications.

[EN]The exploitation of marine wave energy resource has led to the design of numerous Wave Energy Converter (WEC) configurations. The power absorption of a WEC is tightly related to its physical properties and the characteristics of the incoming wave front. Additionally, the operational range of a WEC is limited to certain characteristics of the incoming waves. These restrictions are usually related to limitations in the maximum force of the Power Take-off (PTO) system and the safety of the WEC. As a result, the power production of the WEC must be stopped during sea states of high wave elevation. With the objective of improving the operation of a WEC during these sea states, a Field Weakening (FW) control functionality is proposed to be implemented in the control system of a single-body linear in heave oscillating point absorber with a Permanent Magnet Synchronous Linear Generator (PMSLG) based electrical PTO system. The aim of the aforementioned functionality is to attenuate the magnetic flux in the PMSLG during sea states of high wave elevation. The influence of the size of a WEC on the benefits of the proposed FW functionality is also studied. To that end, two point absorbers with different size are analysed with NEMOH and a wave-to-wire (W2W) model of each WEC is developed. This W2W model enables analysis of the performance and power production of the WECs at different sea states of interest. The obtained results show a remarkable improvement of the operation of a WEC with the implementation of the FW strategy during sea states of high excitation, which leads to an extension of its operation and subsequent additional energy/hydrogen generation. Authors acknowledge financial support by the Spanish Ministry of Science and Innovation, Agencia Espanola de Investigacion (grant PID2020-116153RB-I00/AEI/10.13039/501100011033) and the University of the Basque Country under the contract (UPV/EHU, GIU20/008) .

In synchrotrons at the European Organization for Nuclear Research (CERN), magnetic measurement systems known as B-trains measure the magnetic field in the main bending magnets in real-time, and transmit this signal for the control of the synchrotron’s RF accelerating cavities, magnet power converter and beam monitoring systems. This work presents an assessment of the capabilities and performance of the new FIRESTORM (Field In REal-time STreaming from Online Reference Magnets) system as part of the first phase of commissioning. A short summary of the architecture of the measurement system is provided first, followed by the definition of an error model which can be used to characterize random and systematic errors separately. We present a procedure for the metrological calibration and qualification of the B-trains, including an experimental evaluation of the different error sources for the four new systems being commissioned in the Proton Synchrotron Booster (PSB), Low Energy Ion Ring (LEIR), Proton Synchrotron (PS) and the Extra Low ENergy Antiproton (ELENA) ring. In particular, we discuss a method to calibrate systematic gain and offset errors based on the RF cavity frequency offset needed to center the beam on its theoretical orbit.

This paper discusses design optimization of an electromagnetic soft actuator composes of two antagonistic solenoids that share a permanent magnet core. First, calculation of the magnetic field and applied force of a solenoid with a permanent magnet plunger is presented as the principal component of this electromagnetic actuator. Design optimization of the coil is discussed considering the geometrical parameters of the coil, including its length, inner and average diameters, number of turns, and packing density while the power consumption is bounded. The impact of the actuator size on the resultant force is presented and scaling limitations are discussed. Then, due to the soft nature of the actuator’s component, the impact of the cross section, that is, lateral deformation of the actuator on the magnetic field at the center of section, is investigated as well. The deformation might happen to the actuator due to the load in the transverse direction, especially when the actuator is made of flexible materials.

Sample preparation is necessary for the determination of analytes in biological matrices. The presence of endogenous compounds makes biological matrices complex to be analyzed. In recent years, different extraction techniques have been proposed in this area. An innovative approach is solid-phase extraction based on magnetic nanomaterials that can be manipulated using magnetic fields. These materials have been used in extraction fields due to their exclusive features, including extremely large surface area, selective adsorption ability, easy separation only by applying an external magnet, and possibilities for surface modification/functionalization. These materials have been used for the determination of various analytes in biological fluids. In this chapter, various magnetic nanomaterials are classified based on their compositions and the recent applications of these materials in the field of bioanalysis under solid-phase (micro) extraction format are reviewed. Also, the analytical performance of the methods is addressed from a preventative and critical point of view.

The needs of the internet of things (IoTs) and the advent of low-power consumption electronic modules are moving energy-harvesting systems, so-called “self-powered electronic devices,” from niche applications to broad-scale practicality. These devices are expected to play a crucial role in the development of next-generation wireless sensor networks (WSN), because the dependence on conventional batteries may become a limiting factor for IoTs electronics in terms of lifetime. Besides, we are always surrounded by undetectable magnetic noise fields, induced by electric power transmission lines and electric devices, which are essentially wasted energy. The question is how we can make this energy useful for such applications? Typically, an electromagnetic generator composed of bulky magnetic cores and bundle of coils is used. Unfortunately, it is too heavy, too large, and their efficiency is too low for practical IoTs applications. Additionally, the introduction of a magneto-mechano-electric (MME) generator recently utilizing magnetoelectric (ME) coupling of piezoelectric and magnetostriction and magnetic interaction of magnet mass may have promise for this, but it has been challenging to harness the full potential of weak and low-frequency stray magnetic noise by using traditional ME composites, owing to the limited magnitude of ME coupling. In this chapter, we discussed trends, challenges, applications, and future developments of this emerging magnetic energy-harvesting technology.

Recently, many efforts have been made to tune the ferromagnetic properties of the semiconductor nanostructures to achieve their importance in variety of modern applications in electronic industries. It becomes challenge for material scientist to perceive a prominent magnetic nanomaterial with controlled spin degrees of freedom. In this chapter, we have emphasized on variation in dopant materials in germanium (Ge) nanostructures and investigation about their behavior as a magnetic material at different operating temperatures. Ge is a group IV element which is diamagnetic in nature. For fabrication of high-speed spintronic devices, industry needs permanent magnetic materials working at high temperature. As Ge is having high mobility, it can be beneficial in high-speed electronics. Ge nanostructures became potential candidate as a ferromagnetic material after doping transition metals. Transition ions such as Mn, Cr, Co, and Fe can convert Ge diamagnetic material to ferromagnetic material. Thus, Ge could be the promising material to use as one of the best ferromagnetic material after doping transition ions in it. The doped Ge nanostructures can be a favorable material for fabrication of electronic devices especially in relation with high-speed spintronic devices.

Analytic solutions of fractional order physical equations are very significant to explain the behavior of mathematical models expressing complex phenomena in engineering and natural sciences. The modified extended tanh-function (METHF) method is an especially capable and highly effective mathematical technique to attain analytic traveling wave solutions. This research proposes to examine the analytic solutions of the time-fractional (2 + 1)-dimensional non-linear Heisenberg ferromagnetic spin chain (HFSC) equation that describes electromagnetic waves in modern magnet theory by using the suggested method and the definition of conformable fractional derivative. We obtain some new analytic solutions of the proposed equation in terms of hyperbolic, trigonometric, and rational functions. The validity and precision of these solutions are also examined. The 2D, 3D, and contour graphs of solutions are given to manifest the physical behavior of the waves with the aid of the Mathematica package program. (C) 2021 Elsevier B.V. All rights reserved.

In this study, the preparation and magnetic properties of Ca–Sr M-type (Ca1-x-yLaxSryFe10.9CozO19) ferrire magnets were investigated. A M-type singlephase calcined powder was synthesized with a composition of x ​= ​0.45, y ​= ​0.18 and z ​= ​0. And a very high magnetic properties of Br ​= ​5425Gauss and iHc ​= ​4602Oe were obtained by the thermal annealing and secondary fine-milling method in the sintered magnets. The magnetic properties greats exceeds that of traditional Sr–La–Co M-type ferrite, which has been the highest grade M-type hard ferrite. By use of the innovative post-processing method, the improvement could be attributed to about 4% and 0.8% increase in motor torque and motor efficiency in comparison to that of conventional process, which will eventually be used in high-efficiency motors.

We present the design and measurement of broadband magnetic composite metamaterial absorber with C-Band absorbing effect. The absorber embeds the periodic array of concentric semicircular copper sheet in the FeSiAlp/epoxy composite material layer. The wave-absorbing properties of the FeSiAlp/epoxy resin composite is greatly improved compared with the simple FR4 matrix material, bandwidth with reflectance less than −10 dB increases from 0 GHz to 8.13 GHz. Simultaneously, due to the introduction of the frequency selective surface (FSS) structure, the absorber performance of the absorber is also improved in C-band. The peak of the absorber appears at 7.46 GHz, and the reflectivity reaches −12.78 dB, and the absorption reaches 94.72%. After optimizing the dimensions of FSS, The FeSiAlp/epoxy resin composite absorber with a thickness of 2.6 mm reached peak simultaneously at 7.46 GHz and 16.64 GHz, and peak reflectance reach −12.78 dB and −18.21 dB, respectively, and corresponding absorption reached 95.68% and 99.70%, respectively. Bandwidths with reflectivity less than −10 dB reaches 8.13 GHz, the absorber has obvious absorption effect in C-band. The experiment basically verified the simulation results. Hence, the absorber with special structure design not only overcomes the problem of narrow absorption band of metamaterials, but also solves the shortcoming of weak C-band absorption effect of magnetic material absorber.

Since the electromagnetic (EM) absorbers have wide uses in many military and civilian applications, much effort has been devoted continuously to broadening the absorption bandwidth while making the thickness as thin as possible. In this paper, we present an ultra-wideband metamaterial absorber composed of periodic stepped-structures of magnetic material with a mixture of carbonyl iron powder and resin. The proposed metamaterial absorber features an ultra-thin thickness of only 0.025 wavelength and an ultra-broad operating bandwidth (defined by absorption larger than 90%) from 1.23 to 19 GHz. The ultra-broadband strong absorption is mainly attributed to the giant magnetic loss of the magnetic material, the structure-induced multi-resonances, and the edge diffraction effects of the stepped structures. In addition, good angular performance is observed for all polarizations. Experiments are carried out and are in good agreements with the simulated ones. We also propose a method to further reduce the weight of the structure without affecting much of the overall absorbing performance. The proposed metamaterial absorber has promising prospects in many real-world applications, such as RCS reduction and EM compatibility.

A reliable and fast switchable adhesive mode is very important in smart climbing robots, medical adhesives, industrial assembly and manipulation systems. However, the flaws in adhesion strength and operability provided by existing methods have long been a knotty problem. Here, by combining octopus inspired sucker and magnet-induced deformation, a magnet-induced deformation enhanced adhesion device (MED) based on magneto-responsive polymer (MRP) was proposed. Reversible adhesion was achieved by switching magnetic fields. Theories and simulations show that geometric size, magnetic field strength, and content of the filling particles all significantly affect the magnet-induced deformation and the enhanced adhesion. Adhesion experiments demonstrate d that for the device with 26.7 vol% Neodymium‑iron‑boron (NdFeB) particles, the enhanced adhesion could reach 65.94 KPa within seconds when the experimental current was 2 A. These results indicated a good durability and responsiveness, which is in agreement with theory. This design provided an inspiration to develop adhesion technology in complex real-world scenarios by applying MRP and other smart materials.

Targeted drug delivery systems aim to increase therapeutic effect within the target tissue or organ, while reducing off-target toxicity associated with systemic delivery. Magnetic drug targeting has been shown to be an effective strategy by manipulating therapeutics inside the body using a magnetic field and an iron oxide carrier. However, the effective targeting range of current magnets limits this method to small animal experiments or superficial parts of the human body. Here we produce clinically translatable magnet designs capable of increasing exposure of tissue to magnetic fields and field gradients, leading to increased carrier accumulation. The iron oxide nanoparticle capturing efficiency was first assessed in vitro using a simple vascular flow system. Secondly, accumulation of these particles, following magnetic targeting, was evaluated in vivo using a range of different magnet designs. We observed that our bespoke magnet produced a 4-fold increase in effective targeting depth when compared to a conventional 1 T disk magnet. Finally, we show that this magnet is readily scalable to human size proportions and has the potential to target 100 nm particles up to a depth of 7 cm at specific locations of human body.

Retaining chemical heterogeneity of 2:14:1 grains and forming continuous grain boundaries are two critical contributions to the strong magnetism in multi-main-phase (MMP) magnets. However, the ideal grain boundary microstructure is usually achieved at the expense of weakening the chemical heterogeneity, which poses a big challenge. Here we report a versatile strategy to balance the chemical heterogeneity and microstructure of MMP Nd-Ce-La-Fe-B magnets through tailoring liquid-phase-sintering. At optimum 1040 °C sintering, MMP magnet with 27 wt% Ce–La substitution level exhibits an equivalent weight-bearing capacity to 40MGOe commercial Nd-Fe-B, which is attributed to the joint contributions from retained chemical heterogeneity, essential densification, homogeneous grain size distribution and continuous intergranular phase network with ordered Ia3¯ structure. When shifting sintering temperature Ts towards the higher or lower range, the deteriorated magnetic properties are dominated by distinct restraints. With Ts above 1040 °C, the decreased coercivity is mainly restrained by the negative role of gradual chemical homogenization and abnormal grain growth, as verified by experimental and simulated results. However, with Ts below 1040 °C, the unsatisfactory magnetic performance mainly roots in insufficient densification and discontinuous grain boundary. These advances may deepen our understanding on designing high-performance MMP magnets with balanced contributions from modified microstructure and retained chemical heterogeneity. Keywords: Multi-main-phase, Liquid-phase-sintering, Chemical heterogeneity, Microstructure

Magnetic nanoparticles show excellent features such as small size, high surface area, active surface that can successfully be modified, low toxicity, and superparamagnetism. These unique features of magnetic nanoparticles make them excellent candidates for the design and fabrication of new functional nanomaterials for the solid-phase extraction processes. Magnetic nanoparticles are directly dispersed in the sample solutions for quick extraction of the target compound/s, as they can be readily recovered by a magnet, which overcomes drawbacks of the conventional adsorbent materials such as time consumption and large volume of samples. This chapter aims to describe and highlight the latest developments in design and preparation of novel magnetic nanoparticles. The methodologies for the synthesis of these nanoparticles, as well as their potential use in the selective extraction of the target compound/s from complex samples (i.e., environmental, biological, food and beverage samples) are demonstrated. © 2020 Elsevier Inc. All rights reserved.

The rapid development in nanotechnology has flourished the electronic industries in such a way that the electronic systems are being densely packed with electrical components within the instrument. This explosive growth of electronic, telecommunication, and instrumentation gives rise to an unwanted and undesirable byproduct, which is a novel kind of pollution called electromagnetic interference (EMI). EMI is a conducted and/or radiated EM signal. The impact of EMI is not limited to the malfunctioning of electronic gadgets, but it also affects human health; for example, a continuous exposure to EM radiation increases the risk of cancer, asthma, heart diseases, migraine, and even miscarriage. EMI shielding refers to the reflection and/or absorption of EM radiations using a material; the material acting as a shielding material prevents the penetration of radiations of high frequencies such as radio waves. The blocking of EM radiation using a barrier made up of a conducting or magnetic material is called EMI shielding. This chapter gives a brief overview of different theories of EMI; comprehensive theoretical aspects including reflection, absorption, and multiple reflection parts; mechanism of EMI shielding; and techniques for measurement of shielding effectiveness. Further, consideration and requirement of EMI shielding is discussed along with a review of composite materials for EMI shielding.

Cluster beam deposition provides the opportunity to create novel, highly uniform nanostructures, and the far-from-equilibrium nature of the processing offers pathways to new materials and phases. Because cluster-based processing produces uniform sub-10 nm nanoparticles, nanostructures can be constructed at the convergence of important magnetic length scales, notably to produce exchange-coupled permanent magnet materials with superior energy densities. Further, the nonequilibrium nature of the condensation process promotes extension of the solid solubility of normally immiscible components, providing opportunities to explore new materials. Here, we report efforts at developing new nanostructures and materials for use in permanent magnet applications.

This chapter deals with the latest developments in the synthesis of biologically relevant heterocycles using heterogeneous magnetic nanocatalysts in water. These catalysts are easily separable from the reaction mixture by using an external magnet and can be reused several times without any significant loss in their catalytic activities. As a result, it becomes a fascinating topic for today's organic chemists. The present chapter will surely make some impact and become a valuable document for those working in this direction.