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Developing high-performance carbon-based materials for environmental and energy-related applications produces solid waste with secondary pollution to the environment at the end of their service lives. It is still challenging to utilize these functional materials in a sustainable manner in different fields. In this study, we demonstrate a cascaded utilization of an Fe3O4@onion-like carbon (Fe3O4@OLC) structure from wastewater adsorbents to a supercapacitor electrode. The structure was formed by carbonizing Fe3O4@oleic acid monodisperse nanoparticles into interconnected Fe3O4@OLCs and subsequent insufficient acid etching. The hollow OLCs in the outside region of the hybrid structure provide high surface area and the encapsulated Fe3O4 nanoparticles in the inside region offer high ferromagnetism. The three-dimensionally interconnected graphitic layers are advantageous for efficient separation and high conductivity. As a result, the maximum saturation adsorption capacity of insufficiently etched interconnected Fe3O4@OLCs can reach up to 90.2 mg g−1 and they can be efficiently separated under a magnetic field. Furthermore, the hybrid structure is thermally transformed into N-doped HOLCs, which are demonstrated to be a high-performance supercapacitor electrode with high specific capacitance and high electrochemical stability. The cascaded utilization of the hybrid structure in this study is meaningful for eco-friendly development of functional materials for environmental and energy storage applications. [ABSTRACT FROM AUTHOR]

Soft shape-shifting materials offer enhanced adaptability in shape-governed properties and functionalities. However, once morphed, they struggle to reprogram their shapes and simultaneously bear loads for fulfilling multifunctionalities. Here, we report a dynamic spatiotemporal shape-shifting kirigami dome metasheet with high deformability and stiffness that responds rapidly to dynamically changing magnetic fields. The magnetic kirigami dome exhibits over twice higher doming height and 1.5 times larger bending curvature, as well as sevenfold enhanced structural stiffness compared to its continuous counterpart without cuts. The metasheet achieves omnidirectional doming and multimodal translational and rotational wave-like shape-shifting, quickly responding to changing magnetic fields within 2 milliseconds. Using the dynamic shape-shifting and adaptive interactions with objects, we demonstrate its applications in voxelated dynamic displays and remote magnetic multimodal directional and rotary manipulation of nonmagnetic objects without grasping. It shows high-load transportation ability of over 40 times its own weight, as well as versatility in handling objects of different materials (liquid and solid), sizes, shapes, and weights. [ABSTRACT FROM AUTHOR]

AbstractMulti-coil active magnetic bearing systems require an efficient controller design to maintain stability, maximize performance, and improve flexibility in high-speed transport systems, particularly those used in electric cars, military, and aerospace. By employing Fourier-based frameworks rather than conventional Laplace-based methods, the work reported here simplifies the AMBs controllers, offering more flexibility to complex dynamics and adaptability to non-linearity. For computational and mathematical brevity, the entire formulation has been linearized around a specific range of uncertainty in this work. The magnetic field pattern with rotor eccentricities is characterized by using a subdomain technique and a perturbation methodology. Complex magnetic field formulations are obtained by the estimation of zeroth and first-order formulae in polar coordinates. For every coil, predictive model-based interpolation functions are constructed and optimal controller settings for stability are found by eigenvalue evaluation. The study enhances accuracy and effectiveness by validating these analytical methods against numerical results, offering deeper insights into rotor dynamics and controller adjustments. [ABSTRACT FROM AUTHOR]

Terahertz (THz) radiation (0.3 to 30 THz) fills the crucial gap between the microwave and infrared spectral range. THz technology is important for applications ranging from imaging to telecommunication to biosensing, but these applications often require precise control and manipulation of the THz frequency and polarization state, which typically requires modulators external to the THz source. A hybrid THz emitter that overcomes this limitation by integrating two THz emitters into a single device to enable pulse shaping and chirality control of the emitted radiation without any external components is demonstrated. The two sources are a spintronic emitter (SE) and a semiconductor photoconductive antenna (PCA). The two emitters respond independently to external parameters: the PCA is controlled by the applied bias voltage, while the SE is controlled by the applied magnetic field. Moreover, a dual‐wavelength excitation scheme allows for control of the relative time delay between the THz emission from each constituent. These properties of the hybrid emitter enable precise control of the mixing of the two signals to control the frequency, polarization, and chirality of the overall THz radiation. This on‐chip hybrid emitter thus provides a powerful platform for engineered THz radiation with wide‐ranging potential applications. [ABSTRACT FROM AUTHOR]

In the present study, a triphasic-based system was prepared using constituents such as Lanthanum Calcium Manganite (LCM) , Cobalt Ferrite (CF) , and Barium Titanate (BT) in different proportions. The composition (1-x)LCM: x(0.7CF-0.3BT) , where x = 0, 0.1, 0.2, 0.3, and 1, was employed to produce the triphasic system-based materials using a solid-state reaction technique. X-ray diffraction results confirmed the development of the triphasic phase in the composites through the JCPDS card number of the major peaks. The average crystallite size calculated from XRD data was found to vary with increasing 0.7CF-0. 3 BT concentration in LCM. FTIR spectroscopy indicates alterations in the main peaks with an increase in content of 0.7CF-0.3BT , suggesting the formation of triphasic composites. The upward trend in dielectric permittivity suggests the successful occurrence of Maxwell-Wagner polarization, indicating relaxor behavior at lower frequency values. Impedance spectroscopy reveals dielectric relaxation and the contribution of charge carriers in triphasic composites, along with the impact of grain and grain boundaries. Magnetization analysis at room temperature approves an increase in saturation magnetization in composites i.e., 0.7LCM-0.3(0.7CF-0. 3 BT) triphasic material exhibiting a maximum saturation magnetization of 13.04 emu/g. Magnetoelectric behaviour is observed in triphasic materials at different AC magnetic fields. The 0.9LCM-0.1(0.7CF-0.3BT) triphasic hydroelectric cell achieved a peak current of 1.29 mA and showed enhanced stability over time. Its I-V characteristics revealed a short-circuit current of 3.5 mA, an open-circuit voltage of 0.85 V, and an off-load power output of 2.97 mW. The triphasic system demonstrates improved structural, electrical, and hydroelectric cell (HEC) performance offering promising prospects for use in magnetoelectric and hydroelectric devices. [ABSTRACT FROM AUTHOR]

The magnetocaloric (MC) properties of many rare earth (RE)-based magnetic solids have been intensively investigated. This research aims to develop suitable MC materials for low-temperature cooling application and to better elucidate their intrinsic properties. We have fabricated four single-phase Sr RE 2 O 4 (RE = Gd, Dy, Ho, Er) oxides and conducted a systematic experimental investigation into their structural, magnetic, and low-temperature MC properties. All these Sr RE 2 O 4 oxides crystallize in an orthorhombic structure (space group Pnma) and exhibit typical geometrical frustration. This frustration arises from the one-dimensional RE ion zigzag ladders along the c -axis, which link the two-dimensional honeycomb lattice in the ab plane. The elements in Sr RE 2 O 4 oxides are uniformly distributed and present with valence states of Sr2+, RE 3+, and O2−, respectively. Large low-temperature MC effects and notable performances are realized in these Sr RE 2 O 4 oxides, determined by the MC parameters of magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change (with a lift of 5 K). These MC parameters under a magnetic field change of 0–70 kOe are as follows: 34.18 J/kgK, 275.88 J/kg, and 30.74 J/kgK for SrGd 2 O 4 ; 18.13 J/kgK, 253.83 J/kg, and 17.54 J/kgK for SrDy 2 O 4 ; 18.81 J/kgK, 354.77 J/kg, and 18.61 J/kgK for SrHo 2 O 4 ; and 22.63 J/kgK, 284.25 J/kg, and 21.97 J/kgK for SrEr 2 O 4. These values are comparable to those of most recently updated low-temperature MC materials with remarkable performances, making these Sr RE 2 O 4 oxides highly interesting for practical cooling applications. [ABSTRACT FROM AUTHOR]

We systematically investigated the dielectric, magnetic, and magnetodielectric (MD) properties of Y-type hexaferrite doped with Al3+ and Ga3+ ions. Al3+ ions preferentially enter the spin-up octahedral lattice sites while Ga3+ ions occupy the spin-down octahedral lattice sites first and then, enter the spin- octahedral sites with the increase in doping amount. The initial magnetization reaches saturation from outside of the hysteresis loops, exhibiting a non-collinear spin order. The step-like increase in magnetization with magnetic field indicates the ferroelectric changes in longitudinal conical spin order. The positive MD effect at low temperatures and the negative MD effect after warming for the doped samples are controlled by non-collinear spin ordering and electron hopping, respectively. The Al-doped and Ga-doped samples exhibit different ferroelectric behaviors driven by magnetic fields. Their ferroelectric phase diagrams were proposed on the basis of magnetic and MD properties. The results associate the physical properties with the doped ions in Y-type hexaferrite. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of the vanishing shear viscosity limit and strong boundary layer problem for the compressible, viscous, and heat-conducting planar MHD equations. The main aim is to obtain a sharp convergence rate which is usually connected to the boundary layer thickness. However, The convergence rate would be possibly slowed down due to the presence of the strong boundary layer effect and the interactions among the magnetic field, temperature, and fluids through not only the velocity equations but also the strongly nonlinear terms in the temperature equation. Our main strategy is to construct some new functions via asymptotic matching method which can cancel some quantities decaying in a lower speed. It leads to a sharp L ∞ convergence rate as the shear viscosity vanishes for global-in-time solution with arbitrarily large initial data. [ABSTRACT FROM AUTHOR]

In this paper, we obtain the global-in- x Sobolev stability of Prandtl layer expansions for 2-D steady incompressible MHD flows with shear outer ideal MHD flows (1 , 0 , σ , 0) (σ ≥ 0) on a moving plate. It is worth noticing that in the Sobolev sense, the degeneracy of the tangential magnetic field in our result is allowed, which is much different from both the unsteady case in [25–27] and the steady case in [3,4]. [ABSTRACT FROM AUTHOR]

Self-dual electromagnetic fields are shown to be maximally chiral. Monochromatic self-dual beams have electric and magnetic fields that are eigenstates of curl. The chiral density and chiral current of self-dual monochromatic beams are proportional to the energy and momentum densities. Their energy and momentum densities do not oscillate in time. Self-dual pulses based on an oscillatory solution of the wave equation lack the oscillations of non-self-dual pulses based on the same wave function. All of these properties could be significant in physical applications, but few self-dual fields seem to have been studied experimentally. [ABSTRACT FROM AUTHOR]

Transient receptor potential vanilloid subtype 1 (TRPV1) is a nonselective cation channel involved in various physiological processes such as pain perception, thermoregulation, and inflammatory responses. Nanomaterials have emerged as precise tools to modulate TRPV1 activity, offering high spatiotemporal resolution and specificity. These nanomaterials act as transducers, responding to internal or external stimuli such as pH, light, electric, and magnetic fields to deliver modulatory agents like agonists, antagonists, heat, reactive species, and mechanical forces to TRPV1 channels. This strategy enables non‐invasive and targeted therapeutic interventions for diseases associated with TRPV1 dysfunction. In this review, recent advances are highlighted in nanomaterial‐mediated TRPV1 modulation and its biomedical applications. The TRPV1 structure and activation mechanisms, the integration of nanomaterials for effective TRPV1 modulation, and the required material properties are covered. Moreover, biomedical applications are discussed, including neurostimulation, neurological disorder therapies, cancer therapies, metabolic disease treatments, and cardiovascular disease interventions. Future research directions and challenges in this field are also proposed. [ABSTRACT FROM AUTHOR]

In the framework of the London model, computer modeling has been carried out and the distribution of the magnetic field in a massive superconductor of the II kind has been found, taking into account changes in the inhomogeneity of the magnetic field of an irregular vortex lattice. It is shown that the line shape changes significantly depending on the vortex lattice irregularity. This change should be taken into account when interpreting experimental data on the observation of the local magnetic field, the consideration of this circumstance can change the conclusions concerning the type of vortex lattice and the parameters of the superconductor. [ABSTRACT FROM AUTHOR]

Photocatalysis is an effective way to convert solar energy to chemical energy. Recently, integrating magnetic field into a photocatalytic system has been found effective to improve the photocatalytic performance by inhibiting the charge recombination. In spite of its great promise, such magnetic field assisted photocatalysis is still in its infancy stage, and there is a lack of in-depth understanding on the reaction mechanism and principles for the rational design of photocatalysts. In this review, we summarize the recent progress on the magnetic field assisted photocatalysis. The origin of magnetism is firstly discussed for better understanding on the mechanism of magnetic field assisted photocatalysis. The effect of magnetic field on photocatalysis in the ways of electron spin polarization, negative magnetoresistance (MR) effect and Lorentz force is then discussed. Finally, perspectives and challenges of the further development of magnetic field assisted photocatalysis are also discussed. • Magnetic field assisted photocatalysis has attracted increasing interest. • Understanding the basic principles of the magnetic field assisted photocatalysis for designing efficient photocatalysts. • Diversified photocatalysts with high catalytic efficiency are highly expected. [ABSTRACT FROM AUTHOR]

Technological advances in fMRI including ultra-high magnetic fields (≥ 7 T) and acquisition methods that increase spatial specificity have paved the way for studies of the human cortex at the scale of layers and columns. This mesoscopic scale promises an improved mechanistic understanding of human cortical function so far only accessible to invasive animal neurophysiology. In recent years, an increasing number of studies have applied such methods to better understand the cortical function in perception and cognition. This future perspective article asks whether closed-loop fMRI studies could equally benefit from these methods to achieve layer and columnar specificity. We outline potential applications and discuss the conceptual and concrete challenges, including data acquisition and volitional control of mesoscopic brain activity. We anticipate an important role of fMRI with mesoscopic resolution for closed-loop fMRI and neurofeedback, yielding new insights into brain function and potentially clinical applications. This article is part of the theme issue 'Neurofeedback: new territories and neurocognitive mechanisms of endogenous neuromodulation'. [ABSTRACT FROM AUTHOR]

Background: Effect of temperature fluctuations on the thermo-mechanical properties of engineering materials can be critical in many engineering applications. Moreover, electromagnetic fields also affect the stresses and their distribution in addition to thermo-elastic stresses in some engineering materials, leading to a complex coupling between different energy domains. Purpose: The proposed model enhances its ability to describe long-term interactions and memory effects by incorporating a non-singular kernel and non-local behavior. This suggestion is important because traditional thermoelasticity models often ignore non-local effects. Methods: Thermoelastic interactions in a thin, long, hollow tube immersed in a uniform electromagnetic field are considered. The Laplace transform method was applied to solve the governing equations in the transformed field, and the Dubner and Abate technique was applied to calculate the numerical results for the system fields. Results: The results presented in the graphs were discussed, analyzed, and compared with the results of the corresponding traditional and generalized thermoelastic models, and the effect of operating factors and fractional order was studied. Conclusion: Changing the fractional derivative order improves memory and heredity. This slows changes in electric and magnetic fields and emphasizes dispersion. [ABSTRACT FROM AUTHOR]

Purpose: The vibration characteristics of an isotropic and homogeneous elastic hollow cylinder with double porosity, emphasizing the influence of the magnetic field in the context of nonlocal elasticity, are investigated. The constitutive relations and governing equations are described in the radial direction. Methods: A technique of time-harmonic vibration is implemented to derive a set of ordinary differential equations from the governing equations. The frequency equation for the vibration continuation is established under the conditions of traction-free boundary conditions. MATLAB software is employed with a numerical iteration method to explore free vibration analysis. Results: Analytical results have been authenticated with Computer-simulated numerical results and are presented through graphical representations illustrating the frequency shift for both the nonlocal and local elastic cylinders with double porous structures under the influence of a magnetic field. Conclusion: Numerically simulated data are tabulated to depict natural frequencies as a function of the mode numbers. The distinct behaviors associated with specific modes and the tendency towards linearity as the mode numbers increase highlight the intricate interaction between the magnetic field and the dynamic attributes of the system. [ABSTRACT FROM AUTHOR]

Antimicrobial materials are crucial for high‐touch surfaces to prevent the adhesion and proliferation of microorganisms, playing a key role in infection control measures. In this work, a magnetoelectric nanocomposite able to exert antimicrobial activity when magnetically stimulated, is obtained by solvent casting. The nanocomposites, composed of poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV) and cobalt ferrite magnetostrictive nanoparticles (CFO NPs), respond to a variable magnetic field by mechanically stimulating the piezoelectric component of the material, thereby inducing an electrical polarization. The antimicrobial properties of the material are determined by exposing it to different frequencies (0.3 and 1 Hz) using a custom‐designed magnetic bioreactor, where the resulting electrical microenvironments are the contributing factor. The growth of Escherichia coli and Staphylococcus aureus over the nanocomposite is highly inhibited when magnetically stimulated (dynamic conditions) mainly at 0.3 Hz, in contrast to static conditions. The electric microenvironment is further measured upon magnetic stimulation, with PHBV films with 20% CFO inducing a voltage variation of ≈20 µV at the surface while the films with 10% CFO induced a voltage variation of ≈12 µV. This work demonstrated that magnetic stimulation, combined with magnetoelectric materials, can be used for remote antimicrobial control, thus preventing the spread of infections. [ABSTRACT FROM AUTHOR]

Pulsed electromagnetic fields (PEMF) have been used in bone fracture healing for many years. However, it is still not clear which frequencies are more effective. Therefore, the aim of this study was to investigate the effect of single frequency of 4 Hz and a package of multiple frequencies (220 Hz, 727 Hz, 880 Hz and 10 kHz) on bone fractures of rats. Rats were randomly divided into three groups: sham, R4 and RM. A transverse osteotomy was created in the right medial tibias diaphysis of each rat under anesthesia. The right tibia of the rats in the R4 and RM groups was exposed to 4 Hz, and a package of multiple frequencies, respectively. The rats in both irradiation groups were exposed to a pulsed magnetic field with an amplitude of 10 mT for 1 h/day during 1 month under anesthesia with ketamine (90 mg/kg, i.p.) and xylazine hydrochloride (9 mg/kg, i.p.). The rats in the sham group were kept under the same experimental conditions without any field exposure. At the end of the study, the right tibia of each rat was removed and bone healing was evaluated histopathologically and radiologically, and the concentrations of some elements were measured, such as Na, Mg, K, Cr, Mn, Fe, Zn, Se, Ca and P. The results showed that 4 Hz exposure was more effective in bone fracture healing than the other frequencies in this study. Further studies need to be conducted to determine the mechanisms underlying the effect of 4 Hz PEMF. [ABSTRACT FROM AUTHOR]

Background: Low‐to‐zero fluoroscopic navigation systems lower radiation exposure which improves health outcomes. Conventional x‐ray fluoroscopy (CF) has long been the standard to guide to catheter location for cardiac ablation. With advancements in technology, alternative safety navigation systems have been developed. Three primary modalities commonly utilized are three‐dimensional electroanatomic mapping (3D‐EAM), magnetic navigation system (MNS), and intracardiac echocardiography (ICE), all of which can reduce radiation exposure during the procedure. Objective: We aim to compare the efficacy and safety among ICE, EAM, MNS, and CF in ablation of atrioventricular nodal reentrant tachycardia (AVNRT). Methods: This is a meta‐analysis consisting of observational studies and randomized controlled trials, which evaluated the performance of navigation systems of catheter ablation in AVNRT patients. Primary endpoint was to access the AVNRT recurrence after the procedure during follow‐up periods. Secondary endpoints were technical success, fluoroscopic time, fluoroscopic dose area product, radiofrequency ablation time, and adverse events. Random‐effect model was applied for pooled estimated effects of included studies. Results: A total of 21 studies (21 CF, 2 ICE, 9 EAM, 11 MNS) including 1716 patients who underwent catheter ablation for AVNRT treatment were analyzed. Of these, 16 were observational studies and 5 were randomized controlled trials. Primary outcome: Point estimation of AVNRT recurrence showed ICE exhibited a pooled odds ratio (ORs) of 1.06 (95% confidence interval [CI]: 0.064–17.322), MNS with ORs of 0.51 (95% CI: 0.214–1.219], and EAM with ORs of 0.394 (95% CI: 0.119–1.305) when compared to CF. Secondary outcomes: EAM had significant higher technical success with ORs of 2.781 (95% CI: 1.317–5.872) when compared to CF. Regarding fluoroscopy time, EAM showed the lowest time with mean differences (MD) of −10.348 min (95% CI: −13.385 to −7.3101) and P‐score of 0.998. It was followed by MNS with MD of −3.712 min (95% CI: −7.128 to −0.295) and P‐score of 0.586, ICE with MD of −1.150 min (95% CI: −6.963 to 4.662) with a P‐score of 0.294 compared to CF, which has a P‐score of 0.122. There were insignificant adverse events across the procedures. Conclusion: AVNRT ablation navigated by low‐to‐zero fluoroscopic navigation systems achieves higher efficacy and comparable safety to conventional fluoroscopywhile also reducing risk of radiation exposure time. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to localise the eloquent cortex and measure evoked field (EF) parameters using magnetoencephalography in patients with epilepsy and tumours near the eloquent cortex. Methods: A total of 41 patients (26 with drug-refractory epilepsy and 15 with tumours), with a mean age of 33 years, were recruited. Visual evoked field (VEF), auditory evoked field (AEF), sensory evoked field (SSEF), and motor-evoked field (MEF) latencies, amplitudes, and localisation were compared with those of a control population. Subgroup analyses were performed based on lobar involvement. Evoked Field parameters on the affected side were compared with those on the opposite side. The effect of distance from the lesion on nearby and distant evoked fields was evaluated. Results: AEF and VEF amplitudes and latencies were reduced bilaterally (p < 0.05). Amplitude in the ipsilateral SSEF was reduced by 29.27% and 2.16% in the AEF group compared to the contralateral side (p = 0.02). In patients with temporal lobe lesions, the SSEF amplitude was reduced bilaterally (p < 0.02), and latency was prolonged compared with controls. The MEF amplitude was reduced and latency was prolonged in patients with frontal lobe lesions (p = 0.01). EF displacement was 32%, 57%, 21%, and 16% for AEF, MEF, VEF, and SSEF respectively. Patients in the epilepsy group had distant EF abnormalities. Conclusions: EF amplitude was reduced and latency was prolonged in the involved hemisphere. Distant EF amplitudes were more affected than latencies in epilepsy. Amplitude and distance from the lesion had negative correlation for all EF. EF changes indicated eloquent cortical displacement which may not be apparent on MRI. [ABSTRACT FROM AUTHOR]

The manipulation of the electron spin direction at very low electron energies is demonstrated by exploiting the exchange field present within a magnetic thin film. The design of the lab‐on‐chip integrated magnetic tunnel transistor allows to test different magnetic materials. The variation of film thickness, exchange field strength or electron energy are shown to have an impact on the resulting spin direction of electrons crossing a ferromagnetic material. A controlled engineering of the exchange field in thin magnetic films can therefore serve as a basis of future devices enabling controlled spin manipulation. [ABSTRACT FROM AUTHOR]

Electromedicine can be defined as the study of different types of electrical therapies used for the treatment of various medical ailments. Electromedicine has been practiced for hundreds of years, according to the historical data available. In the early years after the death of Christ, a growing interest in the use of electricity and magnetism was observed. Electrotherapy is the use of electrical energy as a medical treatment. In medicine, the term electrotherapy can apply to a variety of treatments, including the use of electrical devices such as deep brain stimulators for neurological disease. The term has also been applied specifically to the use of electric current to speed wound healing. Electric diathermy uses high-frequency alternating electric or magnetic fields, sometimes with no electrode or device contact to the skin, to induce gentle deep tissue heating by induction or dipole rotation. Additionally, the term "electrotherapy" or "electromagnetic therapy" has also been applied to a range of alternative medical devices and treatments. The aim of this review is to highlight emerging role of electromedicines in health care industries as well as how these are effective as compared to medicines. Moreover, electromedicine offers amazing diagnostic potential. [ABSTRACT FROM AUTHOR]

Based on observations conducted at the Ernest Gurtovenko Horizontal Solar Telescope, the height of the polar chromosphere of the Sun was determined for the period 2012–2023. The measurement was calculated as the difference between the positions of the maximum radial brightness gradients in the continuum and at the core of the Hα line. The results indicate that the height of the polar chromosphere is lower near the maximum of the solar cycle (approximately 4500 km, or 6.3″) and higher near the minimum of the cycle (approximately 5000 km, or 6.9″). The chromosphere's height at the southern pole in 2012–2013 and, particularly, 2016–2017 was higher than at the northern pole. This north–south asymmetry is likely related to differences in the dynamics and magnitude of the polar magnetic fields during Solar Cycle 24. The findings demonstrate that the time changes in the chromosphere's height closely correlate with sunspot numbers, the strength of the polar magnetic field, and chromospheric indices of solar activity. The correlation coefficient between the average annual height of the chromosphere and the smoothed relative sunspot number is –0.64 for the northern hemisphere and –0.75 for the southern hemisphere. The correlation coefficient between the average annual height of the chromosphere and the smoothed values of the polar magnetic field strength (based on data from the Wilcox Solar Observatory) is 0.86 for the northern hemisphere and 0.53 for the southern hemisphere (the latter value increases to 0.77). The correlation coefficient between the average annual height of the chromosphere and the chromospheric index IK2 reaches the highest values, 0.91, for the northern pole and 0.80 for the southern pole. [ABSTRACT FROM AUTHOR]

Direct magnetic field measurements in sunspots by many spectral lines are important for elucidating the true magnitude and structure of the magnetic field at different levels of the solar atmosphere. Currently, magnetographic measurements are the most widespread, but such measurements mainly represent the longitudinal component of the magnetic field. In the sunspot umbra, such measurements give unreliable information and do not allow for determining the actual value of the module (absolute value) of the magnetic field. Such data can be obtained from spectral-polarization observations, thanks to which the magnetic field can be determined directly from Zeeman splitting, rather than as calibrated polarization in line profiles. The presented work presents the results of the study into the magnetic field in the sunspot on July 17, 2023, which was observed on the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. The I ± V profiles of ten photospheric lines of Fe I, Fe II, Ti I, and Ti II were analyzed in detail. The strongest magnetic field measured by the Fe I lines reaches 2600 G, and the difference in the measured intensities by these lines is sometimes at the level of 50–80%. The umbral lines of Ti I show, in general, the same magnetic fields as Fe I lines, while the lines of Fe II and Ti II show significantly weaker fields. Although the lateral field profile in the spot by most of the Fe I lines is smooth, quasi-Gaussian, one of the lines, namely Fe I λ 629.10 nm, shows a "dip" at 400–600 G in the sunspot umbra, which, most likely, is real. The obtained data probably indicate a combination of at least two effects: the dependence of measurements on the height of line formation in the solar atmosphere and the manifestation of Zeeman "saturation" in lines with different Lande factors. It also turned out that the umbral line of Ti I λ 630.38 nm shows somewhat stronger magnetic fields compared to non-umbral lines. The obtained data are planned to be used to clarify the general picture of the magnetic field in the spot by means of simulation. [ABSTRACT FROM AUTHOR]

Magnetorheological (MR) fluids are utilized to develop a variety of electromechanical devices that have potential applications in the automotive, medical, aerospace, and other areas. Since yield stress is the most important design parameter of an MR fluid and its devices, it is dependent on the types of operational modes. This paper thoroughly examines the effects of the operational modes of MR fluids such as shear mode, and squeeze mode along with the impact of mixed-mode operation on the performance of MR fluids and devices. The study found that mixed-mode operation results in higher yield stress and offers better performance control for MR fluid devices compared to single-mode operation under the same working conditions. Several factors impact the performance of MR fluid devices in various operational modes discussed in the paper such as geometry, initial gap thickness, temperature, pressure, velocity, applied compressive strain, response time, magnetic particle composition, magnetic field, and other working factors. Therefore, there is a necessity to thoroughly examine the rheological and mechanical behaviors of MR fluids and the performance of MR devices in different operational modes and working circumstances, highlighting the experimental and theoretical findings conducted by researchers. [ABSTRACT FROM AUTHOR]

The linear and nonlinear Hall effects in 2D electron gas are considered theoretically within the isotropic k‐cubed Rashba model. It is shown that the presence of an out‐of‐plane external magnetic field or net magnetization is a necessary condition to induce a nonzero Berry curvature in the system, whereas an in‐plane magnetic field tunes the Berry curvature leading to the Berry curvature dipole. Interestingly, in the linear response regime, the conductivity is dominated by the intrinsic component (Berry curvature component), whereas the second‐order correction to the Hall current (i.e., the conductivity proportional to the external electric field) is dominated by the component independent of the Berry curvature dipole. [ABSTRACT FROM AUTHOR]

Magnetoelectric nanoparticles (NPs) present an important class of nanomaterials with a wide interest in piezocatalytic and biomedical applications. Herein, the results of magnetoelectric and magnetization measurements performed on core–shell NPs having magnetic core (MnFe2O4, MFO) and ferroelectric shell (Ba0.85Ca0.15Ti0.5Zr0.5O3, BCZT) synthesized by the microwave hydrothermal method are reported. Magnetic results are compared with the measurements on reference MFO NPs prepared under identical conditions. Detailed SQUID magnetometer measurements of the magnetization hysteresis loops M(H) down to 2 K reveal the existence of a clear exchange bias effect in pure MFO NPs attributed to the coexistence of ferromagnetic and antiferromagnetic short‐range interactions. When the magnetic core is covered by the thin ferroelectric BCZT shell, it is observed that 1) the shell suppresses the apparent bias effect and 2) induces an "extra" ferromagnetic magnetization at T < 20 K. The results indicate that this "extra" ferromagnetism has a 2D character and it is most likely related to the interface interactions between the MFO core and BCZT shell. Ferroelectric properties and strong magnetoelectric effect in core–shell NPs are revealed via piezoresponse force microscopy under magnetic field. The mechanisms of the observed effects are discussed. [ABSTRACT FROM AUTHOR]

Wave trains of magnetic field and ion-flux oscillations generated upstream of the ramp of interplanetary (IP) shock were studied according to BMSW plasma-spectrometer measurements of energy–time spectra of the solar-wind ions supplemented by magnetic-field measurements. It was shown that oscillations of the magnetic field upstream of the ramp of IP shock are accompanied by oscillations of the ion flux. A detailed analysis of two cases is carried out, and the results of statistical study are presented. Right-handed circular or elliptical polarization was observed in all wave trains of magnetic-field oscillations, which is consistent with the characteristics of magnetosonic oscillations corresponding to the low-frequency branch of whistler waves. It was obtained that the mean angles between the propagation direction of whistler waves relative to the magnetic field and shock normal direction were 31° and 40°, respectively. This result suggests that the wave packets upstream of the ramp of IP shock had the properties of propagating whistler waves. It was found that, on average, with an increase in the angle of propagation of whistler waved relative to the shock normal direction θkn, the angle between the wave vector and magnetic-field direction θkB decreases. [ABSTRACT FROM AUTHOR]

MMS four-spacecraft observations with high temporal and spatial resolution made it possible to study the characteristics of intense superthin current sheets (SCSs) with a current density J > 30 nA/m2, formed in bursty bulk flows (BBFs), propagating in the Plasma Sheet (PS) of the magnetotail from the remote X line. Statistical analysis of >1000 SCSs observations showed that, in the majority of cases, the current in the SCSs is parallel to the ambient magnetic field and is carried by field-aligned accelerated electron beams. The half-thickness of the SCSs is several electron gyroradii, and in such thin layers the electric current is carried by demagnetized electrons. Bursts of strong nonideal electric fields E' > 10 mV/m are often observed at the edges and/or inside the SCSs. The generation of such fields brings about energy conversion in the SCSs of hundreds of pW/m3, and in some cases up to several nW/m3, which is comparable to the energy conversion in the electron diffusion region of magnetic reconnection. The strongest energy release is observed in the SCSs formed in the fastest BBFs and under strong variations of the magnetic field in the tail lobes. [ABSTRACT FROM AUTHOR]

Studying the Magellanic System can help us understand the role that magnetic fields play in the evolution and structure of interacting low-mass galaxies. We have measured the Faraday rotation measure (RM) of 185 extra-galactic radio sources behind the Large Magellanic Cloud (LMC) to determine the structure of the magnetic field of the LMC. These observations were conducted with the CSIRO Australia Telescope Compact Array (ATCA) with a frequency range of 1.6–3.0 GHz. Our observations double the density of the grid of RMs for the LMC. With these new RM observations in conjunction with previous measurements, we find that the |RM| on the east side of the LMC is greater than the west. Using dispersion measure information from known LMC pulsars, we find that the magnitude of the coherent line-of-sight (LOS) magnetic field, |$B_{||}$|⁠ , is weakest to the north-west of the LMC, and the random LOS magnetic field is stronger in the east side. We find that |$B_{||}$| traces neutral hydrogen arm-like structures within the LMC. Overall, the LMC does not appear to have a magnetic field like that of the Small Magellanic Cloud and Magellanic Bridge, indicating that the LMC is not directly part of the 'pan-Magellanic' magnetic field. [ABSTRACT FROM AUTHOR]

This article investigates the dynamic features of domain walls in a bilayer piezoelectric-magnetostrictive heterostructure under the influence of piezo-induced strains, inertial damping, and dry friction dissipation. We assume that the magnetostrictive material belongs to the transversely isotropic hexagonal crystal. The analysis is carried out within the framework of the inertial Landau-Lifshitz-Gilbert equation, which describes the ultrafast evolution of magnetization inside the magnetostrictive materials. By employing the classical traveling wave ansatz, the study explores how various factors such as magnetoelasticity, dry friction, inertial damping, crystal symmetry, and a tunable external magnetic field characterize the motion of the magnetic domain walls in both steady-state and precessional dynamic regimes. The results present valuable insights into how these key parameters can effectively modulate dynamic features such as domain wall width, threshold, Walker breakdown, and domain wall velocity. The obtained analytical results are further numerically illustrated, and a qualitative comparison with recent observations is also presented. [ABSTRACT FROM AUTHOR]

Structural and magnetic properties of the Shastry-Sutherland material Yb2Pt2Pb were studied in single-crystalline form under pressures up to 10 GPa, magnetic fields up to 17 T, and temperatures down to 0.3 K. Surprisingly robust magnetic order is observed with the Néel temperature TN = 2.1 K stable up to 8.1 GPa. Indication of an additional magnetic phase formation can be traced in resistivity data for magnetic field along the c-axis exceeding the (pressure-dependent) metamagnetic transition. The related anomaly shifts to higher temperatures with increasing field, merging TN at the tricritical point. Experiments with μ0H // [110] revealed the pressure stabilization of observed magnetic phases with respect to the magnetic field. The crystal-structure type is stable up to 10 GPa, without any sign of symmetry change, exhibiting moderate volume compressibility with bulk modulus B = 116(13) GPa, in good agreement with B = 118 GPa provided by the density functional theory. [ABSTRACT FROM AUTHOR]

Solar eruptions, primarily manifested as solar flares, filament eruptions and coronal mass ejections, represent explosive releases of magnetic energy stored in the solar corona, with the potential to drive severe space weather. The initiation of solar eruptions remains an open question, leading to various theoretical models that are inferred from observations. However, these models are subjects of debate due to the absence of direct measurements of the three-dimensional (3D) magnetic fields in the corona. Numerical simulations, based on solving magnetohydrodynamics (MHD) equations that govern the macroscopic dynamics of solar corona, serve as a touchstone for testing these theoretical models. One early proposed model suggested that eruptions could be triggered by reconnection within a single sheared magnetic arcade, which is known as the tether-cutting reconnection model, but it was never confirmed through 3D MHD simulations until very recently. Consequently, two models have gained more popularity: one involving the eruption of a twisted magnetic flux rope (MFR) due to ideal instability (or loss of equilibrium), and the other known as the breakout eruption, which requires a quadrupolar configuration with a delicately located magnetic null point. Other mixed mechanisms, involving both ideal instability and reconnection, are also proposed in association with localized magnetic flux emergence. Now with the validation of the tether-cutting model, the fundamental mechanisms are boiled down to two types of models, one primarily based on the ideal instability of a pre-existing MFR, and the other based on the reconnection of sheared field lines with or without an MFR. Recently, the modelling of the birth of solar eruption using observed data-based MHD simulations has advanced rapidly, becoming a crucial research tool in the study of the initiation mechanisms. These realistic modellings reveal a higher level of complexity compared to all currently available theories and idealized models. [ABSTRACT FROM AUTHOR]

Over 700 bright millisecond-duration radio transients, known as fast radio bursts (FRBs), have been identified to date. Nevertheless, the origin of FRBs remains unknown. Two repeating FRBs (FRB 20121102A and FRB 20190520B) have been verified to be associated with persistent radio sources (PRSs), making them the best candidates to study the nature of FRBs. Monitoring the variability in PRSs is essential for understanding their physical nature. We conducted 22 observations of the PRSs linked to FRB 20121102A and FRB 20190520B using the Karl G. Jansky Very Large Array, to study their variability. We have observed significant flux variability for the PRSs of FRB 20121102A and FRB 20190520B, with a confidence level exceeding 99.99%, based on the observations covering the longest timescale recorded to date. The observed variability of the two PRSs exhibits no significant difference in amplitude across both short and long timescales. We found that the radio-derived star formation rates of the two FRB hosts are significantly higher than those measured by the optical H α emissions, indicating that their host galaxies are highly obscured or most radio emissions are not from star formation processes. The observed timescale of PRS flux evolution constrained the magnetic field of FRB 20121102A with B ∥ ≳ 1 mG and FRB 20190520B with B ∥ ≳ 0.1 mG. [ABSTRACT FROM AUTHOR]

Superconducting cyclotron can generate high-energy proton beams and are mainly used for radiation therapy of tumors and cancers. In the superconducting cyclotron SC200, the maximum magnetic induction intensity can typically reach up to 4.6 T, and the magnetic field accuracy is 1e-4. Hall probes are commonly used tools for measuring high-intensity magnetic fields. Through comprehensive consideration, this study selects the SENIS Low-Noise Teslameter 3MH5 and Hall probe C to measure the magnetic field. When the magnetic field exceeds the range of 2 T, the measurement accuracy of the Hall probe is less than 1e-4, and the Hall probe needs to be calibrated to improve its measurement accuracy. The Hall probes are calibrated using Swiss METROLAB PT2025 nuclear magnetic resonance (NMR) Tesla instrument and 1062 probe. Based on the calibration principle, a calibration system platform was built, test data were collected, and calibration curves were obtained. At the same time, the calibration data were analyzed through cross-validation experiments using the cubic polynomial fitting method. The results indicate that the test deviation range is from −0.1 g to 0.1 g, and the measurement accuracy can reach 1e-4. In summary, the Hall probe can accurately measure the magnetic field distribution of the superconducting cyclotron. It can provide accurate and important data for the calculation and analysis of particle beam dynamics. [ABSTRACT FROM AUTHOR]

The magnetic field is traditionally presented as a (pseudo)vector quantity, tied closely to the cross product. Though familiar to experts, many students find these ideas challenging and full of subtleties. Building on earlier work in rotational physics, we present an alternative pedagogical approach that describes magnetic fields using bivectors. These objects can be visualized as oriented tiles whose components form an antisymmetric matrix. Historically, bivectors have been mostly used in specialized contexts like spacetime classification or geometric algebra, but they are not necessarily more complicated to understand than cross products. Teaching magnetism in this language addresses common student difficulties, generalizes directly to relativity (and extra dimensions), and brings fresh insight to familiar ideas. Editor's Note: For many reasons, magnetism is extremely challenging for the introductory physics student. Magnetic forces are non-intuitive and jarringly different than electric forces. Problems involving magnetism traditionally require three-dimensional reasoning, cross products, and right-hand rules. It is natural to wonder whether new teaching approaches can help students learn such a difficult subject. Building on earlier work in rotational physics, this article explores a non-traditional pedagogical approach where bivectors (represented by oriented tiles) are used to teach magnetism. This fresh perspective may help students avoid pitfalls associated with the traditional approach, while also preparing them for more advanced discussions of relativistic electromagnetism. [ABSTRACT FROM AUTHOR]

Monitoring and detecting buried pipelines under concrete pavement are often complex and difficult tasks. The time–frequency electromagnetic technology, with the fast information acquisition and strong anti-interference ability, is first applied in the buried pipeline inspection. The purpose is to verify if this method can monitor and detect the pipelines status change effectively, even if covered by concrete pavement. Three representative scenarios (normal, coating-damaged and leaking) and two types of pavement (plain concrete and reinforced concrete) are created and applied in the simulations with the finite element method. The simulated results are processed and analysed with the proposed method. In the frequency domain, the maximum change of the electric and magnetic field signals for the coating-damaged scenario from the normal one are 0.4% and 9.9% respectively, and 97.7% and 157.7% for the leaking scenario. In the time domain, the shifts of the electric and magnetic field signal peak are 6.2 μs and 6.5 μs respectively when the coating damage occurs, and 11.4 μs and 13.1 μs when leakage appears. The results indicate that the above technology is valid for buried pipelines. Moreover, it can be used to locate and identify the abnormalities and types of concrete pavement can be differentiated. [ABSTRACT FROM AUTHOR]

The detection of defects can be seriously affected by lift-off and tilt effects, which represents significant challenges for eddy current testing (ECT). In this paper, an innovative eddy current sensor with E-core ferrite is proposed to overcome these challenges. The sensor comprises two excitation coils, one receiving coil, and an E-shaped ferrite core. The excitation coils and receiving coil are wound on two sides and the middle of the E-core, respectively. Specially, the two excitation coils are wound in opposite directions, resulting in magnetic field cancellation in the middle receiving coil when there is no defect in the plate. All the design principle, simulation, and experimental verification demonstrate the feasibility and excellent performance of the proposed sensor. Moreover, the proposed sensor can assess the depth of defects and achieve defect localisation based on the proposed measurement method. The results indicate that the defect depth can be accurately classified and identified based on the measured signal amplitude. The localisation of defects on aluminium sheets shows excellent results for depths ranging from 0.6 mm to 2.0 mm. However, for stainless-steel sheets, the defect localisation results show an unexpected error rate of over 15% when the defect depth is less than 1.1 mm. [ABSTRACT FROM AUTHOR]

This paper concerns the free-surface problem of incompressible ideal MHD fluids with velocity damping in a two-dimensional (2D) horizontally periodic slab domain impressed by a uniform horizontal magnetic field. We prove that the problem is globally well-posed for the small initial data and the solution decays exponentially in time to the equilibrium, where both the Taylor sign condition and the surface tension are not required in this paper due to the stabilizing effect of horizontal magnetic field. [ABSTRACT FROM AUTHOR]

Multi-dimensional wireless power transmission is a critical element in the development of capsule robots. To solve the problem caused by the increasing number of functions of new capsule robots and the fact that the traditional three-dimensional receiving coil occupies excessive inner space, a two-dimensional square transmitting coil with an embedded ferrite core is proposed. The proposed transmitting coil consists of two pairs of rectangular solenoid coils distributed radially along the human body. By changing the direction of the current flow, it can generate a two-dimensional magnetic field covering the whole central plane. This paper presents a theoretical model and conducts finite element simulations to analyze the magnetic flux density in the center plane. To evaluate the effectiveness of the proposed system, two prototypes of transmitting coils with and without ferrite cores are created, tested and compared to assess the performance improvements. Results indicate that the transmitting coil with a ferrite core increases the power transfer efficiency from 5.07% to 6.11%. In addition, attitude experiments reveal that the receiving coil efficiently captures sufficient energy at various angles when operated in the center plane. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the 3D incompressible magnetohydrodynamic equations and establish several logarithmically improved regularity criteria in the homogeneous Besov space. These criteria are based on certain assumptions made in the velocity field and pressure, respectively. The first result solely based on the velocity field indicates that the velocity field plays a dominant role in determining the regularity of weak solutions, when compared with the magnetic field. [ABSTRACT FROM AUTHOR]

The paper deals with the steady MHD equations for a viscous incompressible fluid in a bounded and generally multiply connected domain Ω⊂ℝ3$$ \Omega \subset {\mathrm{\mathbb{R}}}&amp;#x0005E;3 $$ with the no‐slip boundary condition for the velocity u$$ \mathbf{u} $$ and inhomogeneous generalized impermeability boundary conditions for the magnetic field b$$ \mathbf{b} $$. The main results concern an appropriate definition of the weak solution (u,b)$$ \left(\mathbf{u},\mathbf{b}\right) $$, its existence, continuous dependence on the data when the data tend to zero, and uniqueness in a "small" neighborhood of the zero solution (0,0)$$ \left(\mathbf{0},\mathbf{0}\right) $$. [ABSTRACT FROM AUTHOR]

We consider a free boundary problem for the two-dimensional plasma-vacuum interface ideal magnetohydrodynamic (MHD) flows. In the plasma region, the flow is governed by the compressible ideal MHD equations, while in the vacuum region, we consider the full-Maxwell equations for the electric and the magnetic fields. At the free interface, driven by the plasma velocity, the total pressure is continuous and the magnetic field on both sides is tangent to the boundary. We establish a linear stability/instability criterion of equilibrium state for the Rayleigh-Taylor (RT) problem and the linear stability for the ideal MHD equations. More specifically, we study the stabilizing effect of impressed magnetic fields upon solutions to the equations obtained by linearization around the equilibrium state. We give the critical magnetic number H c by a modified variational method and prove that the linearized system is stable when the horizontal impressed magnetic field H ¯ = ( H ¯ 1 , 0) satisfies | H ¯ 1 | > H c , while unstable for | H ¯ 1 | < H c . [ABSTRACT FROM AUTHOR]

In this paper, we revisit the Cauchy problem for the three dimensional nonlinear Schrödinger equation with a constant magnetic field. We first establish sufficient conditions that ensure the existence of global in time and finite time blow-up solutions. In particular, we derive sharp thresholds for global existence versus blow-up for the equation with mass-critical and mass-supercritical nonlinearities. We next prove the existence and orbital stability of normalized standing waves which extend the previous known results to the mass-critical and mass-supercritical cases. To show the existence of normalized solitary waves, we present a new approach that avoids the celebrated concentration-compactness principle. Finally, we study the existence and strong instability of ground state standing waves which greatly improve the previous literature. [ABSTRACT FROM AUTHOR]

A numerical study is performed to examine the influence of a non-uniform magnetic field on the thermo-hydraulic behaviour of a ferrofluid. The analysis is done in the context of a differentially heated semi-circular annulus where a magnetic dipole with its distinct location and dipole strength is used to obtain different configurations. The field variables are computed by solving the coupled set of flow equations, energy equations and the Maxwell's magneto-statics equations. A detailed description is provided on the flow and thermal response after observing different parameters at both global and local scale. Comparison of streamlines and isotherms with a reference case of natural convection concludes that the recirculation zones are responsible for the increased velocity and heat transfer magnitudes. Another key finding of the present work is about the possibility to locally improve the thermal performance of heat exchangers at any desired position along the circumference. [ABSTRACT FROM AUTHOR]

We describe a compact calorimeter that opens ultra-low-temperature heat capacity studies of small metal crystals in moderate magnetic fields. The performance is demonstrated on the canonical heavy fermion metal YbRh 2 Si 2 . Thermometry is provided by a fast current sensing noise thermometer. This single thermometer enables us to cover a wide temperature range of interest from 175 µK to 90 mK with temperature-independent relative precision. Temperatures are tied to the international temperature scale with a single-point calibration. A superconducting solenoid surrounding the cell provides the sample field for tuning its properties and operates a superconducting heat switch. Both adiabatic and relaxation calorimetry techniques, as well as magnetic field sweeps, are employed. The design of the calorimeter results in an addendum heat capacity which is negligible for the study reported. The keys to sample and thermometer thermalisation are the lack of dissipation in the temperature measurement and the steps taken to reduce the parasitic heat leak into the cell to the tens of fW level. [ABSTRACT FROM AUTHOR]

• The total magnetic field in the gap of full-compensated nested Halbach cylinders (NHC) dependence on the rotation angle of inner array is described by the cosine modulus function. • High operating frequency, a large amount of working space, ease of use, and a small number of moving parts make NHC effectiveness in realizing the AMR cycle. • Phase shift angles between the rotation of the inner cylinder of NHC and the piston displacement processes in the range of 70 - 90° to ocure a maximum thermal span. • The volume of pumped heat transfer fluid through the regenerator must be 20–30 % of its voids volume. In this study, a numerical model of the Active Magnetic Regenerator (AMR) cycle, implemented in the reciprocal demonstrator, was developed using COMSOL Multiphysics. A nested Halbach cylinder (NHC) array served as the magnetic field source. Additional simulation of an operation of the NHC array was carried out. To eliminate the discrepancies between the heat exchange duration of the heat transfer medium (HTM) and the hot and cold ends of the regenerator, an adequate time dependence of the inner cylinder rotation angle was calculated. The latter provides the symmetrical sinusoidal form of time dependence of the magnetic flux density in the gap of NHC array, which is important for enhancing the performance of a magnetic refrigerator. It was established that in order to achieve a maximal temperature span, it is necessary to shift the phases of the magnetic field insertion/removal and heat transfer fluid pumping processes by nearly half of the operating cycle period. The latter brings the simulated cycle closer to the ideal AMR cycle. [ABSTRACT FROM AUTHOR]

Ternary intermetallic rare-earth-based magnetocaloric compounds (RE 2 TM 2 Y, where RE = Gd, Tb, Dy, Ho, Er, Tm, TM= Ni, Cu, Co and Y = Sn, In, Cd, Ga, Al) have attracted attention lately as magnetic refrigerants in addressing major concerns of the conventional system of refrigeration. Assessment of the amount of heat transferred between cold and hot reservoirs at varying applied magnetic fields through relative cooling power (RCP) determination is costly and experimentally intensive which calls for predictive computational techniques with characteristic precision. In this contribution, intelligent-based predictive models are developed through sine activation function-based extreme learning machine (SELM) and genetically optimized support vector regression (GSVR) with Gaussian (GU) and polynomial (PY) kernel functions for data mapping and transformation using applied magnetic field and ionic radii of the constituent elements as descriptors. The GU-GSVR model exhibits superior performance compared to both the PY-GSVR and SELM models when validated using a testing set of ternary intermetallic rare-earth-based magnetocaloric compounds with improvement of 10.55% and 2.28%, respectively using correlation coefficient (CC) as assessment parameter. During model validation, the developed GU-GSVR also showcases enhanced performance across additional performance metrics, including root mean square error (RMSE) and mean absolute error (MAE). The impact of externally applied magnetic field on the RCP of different ternary intermetallic rare-earth-based magnetocaloric compounds was examined by utilizing the developed GU-GSVR model. The characteristic precision and accuracy of the developed computational intelligent models would enable adequate as well as comprehensive investigation of ternary intermetallic rare-earth-based magnetocaloric compounds for a clean system of refrigeration. [ABSTRACT FROM AUTHOR]

La 0.7 Ca 0.3 MnO 3 (LCMO), with its high temperature coefficient of resistance (TCR) and large magnetoresistance (MR) effect, has emerged as a leading material in the field of new multi-functional ceramics. Enhancing the magnetoresistive effect of LCMO in low magnetic field and expanding its application range is one of the main research goals of this kind of materials. In this work, La 0.7- x Sm x Ca 0.3 MnO 3 (LSCMO) (0 ≤ x ≤ 0.09) ceramic targets with different doping amounts were successfully prepared by sol-gel method, and the influence mechanism of Sm3+ doping on the magnetoresistive effect and electrical transport performance of LSCMO was systematically analyzed. X-ray diffraction (XRD) results showed that the lattice parameters (a,b,c,V) of LSCMO decreased slightly, indicating that the doping amount of Sm3+ at the A-site increased. Scanning electron microscopy (SEM) showed that the grains were closely connected without obvious pores, the grain size decreased slightly. The ρ -T curve shows an obvious metal-insulator (M − I) transition, with the increase of Sm3+, the increase of resistivity, metal-insulator transition temperature (T MI) and ferromagnetic-paramagnetic (FM-PM) transition temperature (T C) move towards low temperature. When x = 0.015, the peak value of TCR reaches 41.94 %·K−1, and when x = 0.06, the peak value of MR reaches 80.25 %, both TCR and MR are improved. The results show that: Sm3+ doping can effectively enhance the electromagnetic transport performance of LSCMO. This material has a very wide application prospect in the fields of magnetic storage, and infrared detection. [ABSTRACT FROM AUTHOR]

The present research focuses on the MHD second-grade nanofluid flow with induced magnetic field and viscous dissipation over an exponentially stretching surface. The solutal and thermal energy equations are analyzed in the presence of thermophoretic effect and variable thermal conductivity. The solutal and thermal slip boundary conditions are imposed on the surface of the sheet. In the mathematical modeling, the Brownian motion, and thermophoresis consequences are also discussed. The physical appearance of the induced magnetic field on the second-grade nanofluid is the central aim of this investigation. The mathematical flow model which is in the form of nonlinear PDEs is transformed into the system of couple ODEs by the usage of suitable similarity variables. These couple equations are tackled numerically with the help Bvp4c Matlab approach. The illustration of parameters on the flow model is discussed via graphs and tables. It is noted that the induced magnetic field profile and velocity of fluid intensify for the stronger values of second-grade parameter. Further, the numerical result shows that skin friction rate boosts via greater estimation of second-grade parameter and it reduces for magnetic Prandtl number. [ABSTRACT FROM AUTHOR]