Distribution Of Magnetic Particles Research Articles

MHD blood flow effects of Casson fluid with Caputo-Fabrizio fractional derivatives through an inclined blood vessels with thermal radiation

This study investigates a fractional-order time derivative model of non-Newtonian magnetic blood flow in the presence of thermal radiation and body acceleration through an inclined artery. The blood flow is formulated using the Casson fluid model under the control of a uniformly distributed magnetic field and an oscillating pressure gradient. Caputo-Fabrizio's fractional derivative mathematical model was used, along with Laplace transform and the finite Hankel transform technique. Analytical expressions were obtained for the velocity of blood flow, magnetic particle distribution, and temperature profile. These distributions are presented graphically using Mathcad software. The results show that the velocity increases with the time, Reynolds number and Casson fluid parameters, and diminishes when Hartmann number increases. Moreover, fractional parameters, radiation values, and metabolic heat source play an essential role in controlling the blood temperature. More precisely, these results are beneficial for the diagnosis and treatment of certain medical issues.

Enhancement of the rheological properties of magnetorheological foam via different constraint volumes foaming approach

The potential of magnetorheological (MR) foam, a recently developed porous smart material, has grown rapidly in recent years. The ability of MR foam to change its properties continuously, actively, and reversibly in response to a controlled external magnetic stimulus is one of its advantages for applications in advanced technology industries. However, its ability to store energy is still relatively low. This study attempts to address this drawback by highlighting a method to improve this ability by enhancing the material's storage modulus by introducing constrained foaming during the fabrication process. MR foam containing 75 wt% carbonyl iron particles (CIPs) was prepared in situ using two foaming approaches: free and constrained foaming. The effect of constraint foaming on the storage modulus enhancement was further investigated by reducing the mold length by 25 % and 50 %. The rheological properties of the fabricated MR foam samples were then examined using a rheometer in both the absence and presence of magnetic fields in an oscillatory shear mode. Thus, this study showed that constraint foaming has successfully improved the properties, especially regarding storage modulus and MR effect. When the mold volume was further reduced by 50 %, the storage modulus increased by about 50 % compared to a free-foaming MR foam at off-state conditions. Meanwhile, the results portrayed a higher storage modulus value under a 0.659 T magnetic field. This positive enhancement was believed to be due to a more compact CIP distribution. Hence, constraint volume MR foams were able to form stronger chain-like structures. The micrograph analysis by digital microscope revealed that the pore size decreased as the mold length was reduced. A shorter mold resulted in a more compact distribution of magnetic particles. As a result, MR foam with constrained foaming, especially at 50 % mold length, has a higher storage modulus. Overall, using constrained foaming to fabricate MR foam could improve the structure and mechanical properties of MR foam for a wide range of smart devices.

Fe3C/Fe@N-doped porous carbon composites with excellent microwave absorption properties

Biomass derived porous carbon has attracted extensive attention in microwave absorption and shielding due to its unique structure and low cost. However, it is a great challenge to improve the impedance matching of electromagnetic wave absorbers by adjusting the distribution of magnetic particles and pore structure. In this research, Fe3C/Fe@N-doped biomass-derived porous carbon composites (Fe3C/Fe@NBPC) is successfully prepared by swelling-freeze-drying and carbonizing. It is worth noting that the uniform distribution of magnetic particles is achieved through the swelling process. The impedance matching performance of Fe3C/Fe@NBPC is effectively improved by adjusting the aperture and doping magnetic particles. The heterogeneous magnetic/dielectric multi-component benefit to superior EMW absorption performance through forming multiple polarizations, magnetic loss, and dielectric loss effects. The optimal Fe3C/Fe@NBPC composites exhibits superior electromagnetic wave (EMW) absorption performance with the minimum reflection loss value of − 52.25 dB and wide effective absorbing bandwidth of 3.06 GHz at 2.71 mm matching thickness. This work provides guidance for designing an efficient biomass derived EMW absorber with low cost, light weight and strong absorption.

Nondestructive inspection and imaging of magnetic hydrogel using the alternating magnetic field infrared thermography

Magnetic hydrogel has great potential application in various fields, such as soft robots, drug delivery and biomedical engineering. We report a testing method, i.e., the infrared thermograph method based on alternating magnetic field excitation for the detection of magnetic hydrogel. We verify the feasibility of concentration evaluation of magnetic nanoparticles in magnetic hydrogels using this method and analyze the relationship between the surface temperature rise rate of the magnetic hydrogel and the nanoparticle concentration. Then, we use this method to inspect and image the distribution of magnetic particles. Besides, we validate that this method is effective for detecting bubble defects in magnetic hydrogel and imaging the three-dimensional distribution of the fibers added in the hydrogel, and metal fibers are mainly concerned. This work provides a clear insight into a nondestructive inspection and imaging method to magnetic hydrogel, and this method can be efficient to detect multiple types of information.

In English

Oil and oil products enters surface waters as a result of man-made disasters, caused, in particular, by military operations. In order to prevent ecological catastrophe, it is necessary to remove hydrocarbons from water surface. The paper is devoted to the development of materials for the extraction of non-polar liquids from aqueous media. Magnetic sorbents based on non-carbonized biopolymers (both plant cellulose and keratin) are proposed. Biopolymer matrices of different morphology on the level of fiber bundles were used for the composite preparation. Dependent on origin, the matrices are characterized by different morphologies at the level of fiber bundles: they are straight (cellulose obtained from wood and corn cobs), helical (cellulose of tea leaves or scaly (keratin from animal wool). Magnetite particles were inserted into biopolymer matrices after the removal of non-cellulose and non-keratin inclusions from them. The samples were investigated with SEM and FTIR techniques, magnetite was identified with XRD analysis. The most homogeneous distribution of magnetic particles, a size of which is less than 1 mm, was found for the matrix obtained from corn cobs. This composite contained the least amount of iron (0.24 mass. %), namely this sample demonstrates the best flotation. The sorbent based on cellulose from tea leaves contained 71% of iron: the particles sink almost completely. The capacity towards non-polar liquids was estimated as follows (g g–1): 1.6–8.6 (vegetable oil), 10.5–16.4 (crude oil), 9.8–14.5 (kerosene). After the removal of crude oil from water surface, no film of this liquid was visually observed. The value of chemical oxygen demand was » 0.2 mgO2 dm–3, this is less than the demand for drinking water. Moreover, the sorbent can be easy removed from water surface with magnet. As found, the sorbents can be used for removal of toxic metal ions from water. As found, magnetic particles improves sorption of Pb2+ ions but decrease Cd2+ sorption. Thus, the sorbents with small content of inorganic modifier can be used for the removal of oil and oil products from water surface. The sorbents, which demonstrate bad flotation, can be used for the recovery of inorganic ions. The advantages of biopolymer-based sorbents over known material is a simple preparation procedure that involves cheap and available feedstock. Moreover, the sorbents can be easy separated from aqueous phase with magnet.

Study on Elucidation of the Roundness Improvement Mechanism of the Internal Magnetic Abrasive Finishing Process Using a Magnetic Machining Tool

The magnetic abrasive finishing process using the magnetic machining tool was proposed to finish the internal surface of the thick tube (the thickness of the tube is 5~30 mm). It has been proved that this process can improve the roundness while improving the roughness. In this paper, we mainly study the machining mechanism of roundness improvement. Firstly, the influence of finishing characteristics on the roundness improvement was discussed, including the rotational speed of the magnetic machining tool and the rotational speed of the tube. It was concluded that the roundness improvement increases with the increase in the rotational speed through the analysis of finishing force and finishing times. Furthermore, the influence on roundness improvement of different distributions of magnetic particles were experimentally compared. After finishing, due to the magnetic force generated by the magnetic machining tool and the magnetic pole unit exerting pressure on the magnetic particles, a fixed magnetic brush is formed. The experimental results show that the circumferential length of the fixed magnetic brush is different due to the different distribution areas of magnetic particles. It was concluded that the roundness improvement increases with the circumferential length of the fixed magnetic brush increases by discussing the relationship between the circumferential length of the fixed magnetic brush and the wavelength of the roundness curve. When the circumferential length of the fixed magnetic brush is 76 mm, the roundness was improved from 379 μm to 236 μm after 60 min of finishing.

Magnetic behavior and chaining of strontium ferrite-nylon composite above the melting temperature

To better understand Magnetic Field Assisted Additive Manufacturing (MFAAM) the effect of a magnetic field on the orientation and distribution of magnetic particles in a molten magnetic composite was studied. Vibrating Sample Magnetometer (VSM) measurements were made on Sr-ferrite/PA12 fused deposition modeling filaments of different packing fraction (5 and 40 wt. %). The rotation of the sample’s magnetic moment upon application of a field perpendicular to the easy axis was monitored with a biaxial VSM above the PA12’s softening temperature. The observed magnetic moment transients depend on the temperature, the applied alignment field, the packing fraction, and the initial field-anneal procedure. Longer field-anneals result in larger time constants and seem to induce a hurdle that prevents complete alignment at low temperatures and/or for small fields. Results indicate the molten composite is a non-Newtonian fluid that can support a yielding stress. Scanning Electron microscopy (SEM) images taken on field-annealed samples at 230 °C show strong chaining with little PA-12 left between individual Sr-ferrite particles suggesting that direct particle to particle interaction is the reason for the observed non-zero yielding stress. The melt viscosity of the composite increases with the number of thermal cycles above the melting temperature (Tm). Room temperature (RT) torque magnetometry measurements show that magnetic anisotropy depends on the field annealing process through induced shape anisotropy contributions originating from magnetic particle agglomerates.

Estimation of Magnetic Force between Micrometer-Sized Fly-Ash Particles in Cementitious Suspensions

Magnetic fly ash is a potential alternative responsive additive to achieve magneto-rheology control of cementitious materials; it reduces the cost of magnetic particles and also is beneficial to preparing sustainable binder materials. This paper estimates the magnetic force between micrometer-sized fly-ash particles in cementitious suspensions. Four cases, regarding different selections of particle distance and different characterizations of magnetic properties of fly ash, are considered. The correlations between theoretical calculated parameters and experimental rheological properties are discussed. Results show that fly ash should be separated into magnetic and nonmagnetic parts to better estimate the magnetic force between particles. For the case of two neighboring magnetic fly-ash particles in cementitious suspensions, the estimated magnetic yield parameter, describing the relative magnitude of magnetic force to the resistance of the suspension, can be used as an indicator to describe whether the fly-ash cement paste shows rheological response to an external magnetic field. The intensity of the magneto-rheological response can be correlated to the average magnetic force calculated by considering the even distribution of magnetic fly-ash particles in nonmagnetic solid suspensions.

Magnetic Porous Carbon Composites for Efficient Electromagnetic Wave Absorption

Biomass carbon composites have the shining points of lightweight, economy, harmlessness, and large specific surface area, casting on them great development prospects in terms of excellent wave absorbing properties. Herein, a facile route to fabricate magnetic porous with a special spongy structure for its great contribution to microwave absorption is reported. It is endowed with a strong absorption capacity and a wide absorption band. The 3D spongy structure and uniform distribution of magnetic Co particles can promote defect polarization, interface polarization, and dipole polarization, which are conducive to scattering and reflection of electromagnetic waves (EMW) in the absorbing body. The magnetic Co particles can enhance the magnetic loss on the one hand and harmonize the impedance matching on the other hand. The minimum reflection loss can reach −54.7 dB. The effective absorption bandwidth at 2.1 mm can reach 7.61 GHz, almost covering the X and Ku bands. This proposed strategy provides more possibilities for the application of biomass microwave absorbers with lightweight and broadband properties.

Novel thin polymeric magnetic membranes study for applications in the future biomedical devices

Biomedical devices such as pumping/mixing fluids, cell-culturing, and drug delivery often use different actuation methods. Magnetic actuation using magnetic particles that are embedded in thin flexible polymeric sheets (membranes) is convenient to use, especially for medical implantable devices such as micropumps, due to the fact they do not require board batteries and exhibit better performances than other actuation methods. The fabrication process of these membranes uses a random distribution of particles. In this work, membranes with a local distribution of magnetic particles are investigated and compared to membranes with randomly distributed magnetic particles, which in turn may enhance the actuation performance for certain applications. Iron oxide particles are embedded into polydimethylsiloxane, and micromagnets are used to localize the position of the magnetic particles within the polymeric mixture during the fabrication process. Three different concentrations are investigated: low (7.5 w/v%), medium (10 w/v%), and high (12.5 w/v%). Static and dynamic measurements of membrane’s maximum deflection values are compared for both types of membranes with a random and a local distribution of magnetic particles. The maximum deflection location is shifted due to the presence of the localized magnetic field for a membrane with a local distribution of magnetic particles. From the experimental results, it is evident that the deflection performance result is much higher for the local distribution of the magnetic particles’ membrane during a static magnetic load and slightly lower during a dynamic (sinewave input) magnetic load at frequencies of 1 and 5 Hz.

Two-Dimensional Basalt/Ni Microflakes with Uniform and Compact Nanolayers for Optimized Microwave Absorption Performance.

It has been accepted that the uniform distribution of magnetic metal particles is beneficial to microwave absorption, while why the homogeneous magnetic particles on the dielectric substrate improve the electromagnetic loss is still unclear. Herein, metal Ni nanoparticles, two-dimensional (2D) basalt/scattered Ni, and basalt/uniform Ni microflakes are obtained through a pretreatment and electroless deposition process. In comparison to Ni nanoparticles and basalt/scattered Ni, the basalt/Ni microflakes with largely uniform and compact Ni nanolayers on basalt, breaking the percolation limit, are favorable for enhanced electromagnetic attenuation. The Ni nanolayers are convenient for construction of a microscale conductive net and migration of an electron. The 2D heterostructures constructed by basalt substrates and decorated Ni layers boost multiple scattering absorption and promote interfacial polarization. Meanwhile, exposed Ni does not inhibit magnetic resonance, enabling strong magnetic coupling. Consequently, the basalt/Ni microflakes with uniform Ni nanolayers demonstrate better microwave absorption with a minimum reflection loss of -30 dB and an effective absorption bandwidth of 3 GHz at 1 mm. This work shows that the uniform and compact magnetic metal nanolayers are effective in improving the dielectric loss and magnetic loss simultaneously to achieve the high-performance microwave absorption.

4D printing of mechanically robust PLA/TPU/Fe3O4 magneto-responsive shape memory polymers for smart structures

The integration of magneto-responsive shape memory polymers (SMPs) into 4D printing provides novel opportunities to create innovative and intelligent products controlled in a contactless method. In this study, a promising SMPs with robustly mechanical property and magneto-responsive behavior were proposed and fabricated into 3D printing feedstock based on polylactic acid (PLA), thermoplastic polyurethane (TPU) and Fe3O4 particles. Results revealed that the 3D-printed PLA/TPU/Fe3O4 possessed robust tensile strength and modulus with a homogeneous distribution of magnetic particles in polymer blends. Also, PLA/TPU/Fe3O4 exhibited excellent shape fix ratio (∼100%), recovery ratio (>91%) and rapid magnetic response within as short as 40 s, suggesting the high efficiency of heat generation by magnetic particles. Moreover, smart structures including honeycomb and bionic flower-like model were designed and printed as an original shape. After programmed by an external force, the folded lattice structure at the temporary shape could recovered completely under a contactless magnetic field. The flower-bud structure sequentially restored layer-by-layer controlled by using three pedals with varied Fe3O4 composites. Consequently, the high-load capacity, fast magneto-responsive behavior and high recovery performance of the proposed multi-material have great potentials in actuator or robots applications via 3D printing.

Optimization of the Antenna Unit of the Superconducting Magnetometer: Research of Weak Magnetic Signals

Introduction. The article describes the optimization of the superconducting antenna design and balancing method of the superconducting antenna of magnetometer. This magnetometer is designed to study the magnetic properties of materials, as well as non-invasive study of the distribution of magnetic particles in organs of small laboratory animals, when toxic particles or drugs are introduced into the animal's body. The superconducting antenna of the magnetometer is a second-order axial gradiometer and is a part of the flux transformer of the SQUID sensor. For stable operation within the dynamic range of the magnetometer, the antenna must have a balance degree of at least 1/1000. Traditionally, it is balanced in a separate tuning module (Helmholtz coils), which creates a homogeneous magnetic field with a high degree of uniformity. The purpose. The problem is that the subsequent displacement of the SQUID magnetometer unit into the measuring complex, even within the laboratory, reduces the degree of balance of the magnetometer due to objects that create a strong gradient magnetic field, which negatively affects the measurements. Results. As a solution of this problem, the some approaches are described in the article. In order to increase the uniformity of the field inside the solenoid and eliminate field distortions at its edges, the using of solenoid with a special arrangement of turns to balance the antenna directly at the measurement site was proposed. The balancing elements for the horizontal components of the magnetic field were eliminated. Also the antenna balancing element in the form of a ring along the vertical component of the magnetic field, which does not violate the symmetry of the antenna was applied. Conclusions. Using this approach, it is possible to optimize the design of the antenna unit and the balancing process of the magnetometer antenna with a sufficient degree of balance in the vertical component directly in the geometric center of the measuring system, which reduced the time of preparing the system for work and improved the metrological indicators of the system. Keywords: superconductivity, SQUID-magnetometry, axial gradiometer, antenna balance, optimization.

Occurrence and Distribution Patterns of Magnetic Particles Within Stalagmite Growth Laminae

AbstractThe concentrations of magnetic particles in stalagmites depend greatly on the regional hydrologic condition, and thus can act as an important proxy for paleoclimate reconstruction. The central axis region of a stalagmite is usually selected for such magnetism study. However, little is known about the distribution and influence factors of exogenetic magnetic particles within the growth laminae. In this study, the occurrence and variations of magnetic particles along the growth laminae of three shape stalagmites were investigated by a set of magnetic measurements, including isothermal remanent magnetization (IRM) acquisition curves and low‐temperature magnetic analysis. The results show the main magnetic remanence carrier is detrital magnetite/maghemite, coexisting with small amounts of hematite and goethite. The distribution of soft magnetic particles along the growth laminae showed different patterns among the three shape stalagmites (dome, cone, and candle). For the dome shape stalagmite, the soft magnetic particle concentrations in all studied growth layers showed an increasing trend from center to edge. Similar patterns were also appeared in the bottom growth layers of the cone and candle shape stalagmites. This edge enrichment of magnetic particles is caused by drip water washing effect. However, such enrichment pattern became weaker or even inverse in the top growth layers of the cone and candle shape stalagmites, indicating that the shapes of stalagmites could also affect the surface distribution of soft magnetic minerals. These uneven distributions of magnetic particles imply that the central axis region of a stalagmite may not always be the optimal specimen for environmental magnetism study.

An overview on properties and applications of magnetorheological fluids: Dampers, batteries, valves and brakes

This paper presents a review of literature that introduces the properties and applications of Magnetorheological fluids(MRFs). first, magnetic particles (iron or cobalt), base fluids(oil (mineral-synthetic) or water), and how to prepare magnetorheological fluids are discussed. Then, in the continuation of this research, considering that magnetorheological fluids are smart and soft liquids, the methods of stability and properties (viscosity, hysteresis loop, Shear yield stress, etc) Of these magnetorheological fluids are discussed. Due to the different properties of Magnetorheological fluids, the behavior of these fluids in different states is discussed. These intelligent fluids change their properties when exposed to an external magnetic field. The most important and obvious feature of magnetorheological fluids is their reversibility from liquid to semi-solid state or vice versa in the Presence or the absence of a magnetic field in a fraction of a second. This change in state and properties is known as the magnetorheological effect. This effect depends on various factors, such as the concentration of magnetic particles, the distribution of magnetic particles, the strength of the magnetic field, additives, and so on. The low magnetic effect and instability of magnetorheological fluids are the most important problems against their widespread use in modern industries. According to research, carbonyl iron particles are the most promising particles for the dispersed phase in MRF. The choice of carbonyl iron particles contributes to their high saturation magnetism, relatively low cost, low coercion, and widespread availability. Finally, according to the different properties and behaviors of these fluids, different applications of magnetorheological fluids are discussed. MRF-based control systems are increasingly used in engineering applications such as rheological magnetic electrolytes in batteries, anti-lock braking systems, magnetic clutches, vibrating dampers, shock absorbers, control valves, and various types of vibrating dampers. One of the newest applications of magnetic fluids is the magneto-rheological electrolyte. The use of MRFs in batteries introduces a new class of magnetic field-sensitive electrolytes that has the potential to increase impact resistance, safety, thermal conductivity, and energy storage in electronic devices through reversible active switching electrolyte mechanical properties.

Self-healing and printable elastomer with excellent shear stiffening and magnetorheological properties

This work reports a novel kind of hybrid magnetorheological elastomer (HMRE) that possesses multi-functions including excellent shear stiffening and magnetorheological (MR) effects, as well as self-healing and printable abilities. The HMRE materials are prepared by embedding carbonyl iron particles (CIPs) into a blend of silicon rubber (SR) and low cross-linking gel-like polyurethane (PU). The relative shear stiffening effect of HMRE-3:1 (the mass ratio of PU and SR is 3:1, and 50 wt% CIPs) is 6095% as the shear frequency increases from 0.1 Hz to 100 Hz, which is about 150 times that of SR based magnetorheological elastomer (MRE). With the magnetic flux density from 0 to 1T, MR effect of isotropic HMRE-3:1 is as high as 266%, which is 3.5 times that of SR based MRE. Notably, HMRE obtains extraordinary mechanical and electrical healing capabilities. HMRE with a destructive cut-through injury can sustain an extensibility of 425% (the initial extensibility ≈ 650%) after healing. Meanwhile, possible mechanisms are proposed to explain the shear stiffening properties, MR effect, and self-healing performance of HMRE. Moreover, the extruded modeling 3D printing of flexible HMRE actuators can be achieved due to the plasticine property of pre-polymerized HMRE, which bestows HMRE with magnetic particle distribution programmability and shape designability. This work may provide a new way for the next-generation multifunctional materials with exceptional shear stiffening behavior, magnetically mechanical properties, self-healabilities, and printable performance.

Magnetic Molecularly Imprinted Polymers: An Update on Their Use in the Separation of Active Compounds from Natural Products.

During the last few years, separation techniques using molecularly imprinted polymers (MIPs) have been developed, making breakthroughs using magnetic properties. Compared to conventional MIPs, magnetic molecularly imprinted polymers (MMIPs) have advantages in sample pretreatment due to their high specificity and selectivity towards analytes as a result of their larger specific surface areas and highly accessible specific binding sites. The techniques of isolation of active compounds from natural products usually require very long process times and low compound yields. When MMIPs are used in sample separation as Solid Phase Extraction (SPE) sorbents, the MMIPs are introduced into the dissolved sample and spread evenly, and they form bonds between the analyte and the MMIPs, which are then separated from the sample matrix using an external magnetic field. This process of separating analytes from the sample matrix makes the separation technique with MMIPs very simple and easy. This review discusses how to synthesize MMIPs, which factors must be considered in their synthesis, and their application in the separation of active compounds from natural products. MMIPs with magnetic core-shells made by co-precipitation can be a good choice for further development due to the high synthesis yield. Further optimization of the factors affecting the size and distribution of magnetic core-shell particles can obtain higher synthesis yields of MMIPs with higher adsorption capacity and selectivity. Thus, they can isolate target compounds from natural plants in high yields and purity.

Magneto-responsive structural build-up of highly flowable cementitious paste in the presence of PCE superplasticizer

Magneto-rheology control, by means of adding magnetizable particles and applying magnetic field, is a potential approach to satisfy the contradicting requirements of fresh properties in different casting processes. Polycarboxylate ether (PCE) superplasticizer is an essential component of modern cement-based materials, which significantly affects the viscoelastic properties of cementitious suspensions, and hence the movement and distribution of magnetic particles after applying an external magnetic field. This present research focuses on the following two aspects: whether highly flowable cementitious paste containing both magnetic particles and PCE shows rheological response to an external magnetic field, and if yes, is there a difference of magneto-responsive structural evolution of cementitious pastes with and without PCE? For these purposes, the magneto-responsive structural build-up of highly flowable cementitious pastes with various magnetic particles (two nano-Fe3O4 particles and one magnetic fly ash) in the presence of PCE, described by the evolution of storage modulus over time, is evaluated. Experimental results show that highly flowable cementitious pastes containing both magnetic particles and PCE indeed exhibit obvious magneto-rheological (MR) responses. The incorporation of PCE significantly increases the relative MR effect while slightly decreases the absolute MR effect. By comparing the magneto-responsive structural build-up of cementitious pastes with and without PCE, it is revealed that the application of an external magnetic field to a highly flowable cementitious paste with PCE mainly plays a significant role in the increase of solid-like properties.

Symmetrically Controlled Design of Twin Alumina-Co Composite Thin Films

Self-assembled dual-working electrode electrolytic cells were designed to produce twin alumina-Co composite films with highly symmetrical microstructures using a deflected electric field-assisted alternating current electrodeposition method. The results show that the deposition current density, microstructure, and optical and magnetic properties of the twin composite films exhibit a high degree of symmetry. The distribution of magnetic Co particles in the alumina nanopores can be changed by adjusting the magnitude of the deflected electric field, resulting in a synchronous symmetrical change in the microstructure of the composite films, which enables the fine-tuning of the magneto-optical properties of the twin alumina-Co composite films at the microscopic scale. The current density distribution on the surface of the twin composite films along the direction of the deflected electric field was quantitatively analyzed by theoretical calculations and numerical simulations. The results show that the deposition current density gradually increases from 0.024 A/m2 in region C to 0.056 A/m2 in region A at 6 V deflection voltage. The saturation magnetization intensity gradually increases along the radial direction, which is 118, 130, and 150 kA/m, respectively

Investigation of the Morphological Structure of Needle-Free Electrospun Magnetic Nanofiber Mats

Electrospun magnetic nanofibers are promising for a variety of applications in biomedicine, energy storage, filtration or spintronics. The surface morphology of nanofiber mats plays an important role for defined application areas. In addition, the distribution of magnetic particles in nanofibers exerts an influence on the final properties of nanofiber mats. A simple method for the production of magnetic nanofiber mats by the addition of magnetic nanoparticles in an electrospinning polymer solution was used in this study. In this work, magnetic nanofibers (MNFs) were prepared by needle-free electrospinning technique from poly(acrylonitrile) (PAN) in the low-toxic solvent dimethy lsulfoxide (DMSO) and 20 wt% Fe3O4 at different parameter conditions such as PAN concentration, voltage and ultrasonic bath. The distribution of nanoparticles in the fiber matrix was investigated as well as the chemical and morphological properties of the resulting magnetic nanofibers. In addition, the surface morphology of magnetic nanofiber mats was studied by confocal laser scanning microscope (CLSM), scanning electron microscope (SEM), Fourier transform infrared microscope (FTIR) and ImageJ software, and distribution of Fe3O4 particles in the matrix was investigated by energy dispersive X-ray spectroscopy (EDX).