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Several parametric effects on the magnetic collection have been evaluated considering dimension, strength of external magnetic field, injected velocity and particle concentration in the working fluid. Besides, accidental environments, expected in the containment of nuclear power plants, have also been addressed for the capture efficiency. The capture efficiency is especially enhanced with magnetic particle size and magnetic field strength through increased magnetic force; the non-magnetic coating thickness and fluid velocity hinder the magnetic collection. Based on the assessment, the magnetic withdrawal system can effectively capture magnetic particles even under accidental environments. Withdrawal of multifunctional magnetic particles or filtering of magnetic impurities can be effectively realized through the system.

We develop a low-cost, mass-production process for creating rod-shaped glass-coated magnetic particles consisting of a magnetic metal core and glass shell structure. We investigate their magnetic properties by analyzing their optical absorbance in suspension as a function of the orientation of a 1 mT magnetic field. From the response we derive that the magnetization of the particles is 0.1 MA/m. We demonstrate an automated system that quantifies and dispenses a large amount of RGMPs by magnetic self-assembly on a high-volume plate patterned with an array of holes. This automatic dispenser can provide packaging forms with the smallest unit of RGMPs for in-vitro diagnostics and is expected to reduce the time and effort required for the assembly and packaging process.

Magnetic-field-induced dispersion of magnetic fillers has been proven to improve the gas separation performance of mixed matrix membranes (MMMs). However, the magnetic field induced is usually in a horizontal or vertical direction. Limited study has been conducted on the effects of alternating magnetic field (AMF) direction towards the dispersion of particles. Thus, this work focuses on the incorporation and dispersion of ferromagnetic iron oxide–titanium (IV) dioxide (αFe2O3/TiO2) particles in a poly (2,6-dimethyl-1,4-phenylene) oxide (PPOdm) membrane via an AMF to investigate its effect on the magnetic filler dispersion and correlation towards gas separation performance. The fillers were incorporated into PPOdm polymer via a spin-coating method at a 1, 3, and 5 wt% filler loading. The MMM with the 3 wt% loading showed the best performance in terms of particle dispersion and gas separation performance. The three MMMs were refabricated in an alternating magnetic field, and the MMM with the 3 wt% loading presented the best performance. The results display an increment in selectivity by 100% and a decrement in CO2 permeability by 97% to an unmagnetized MMM for the 3 wt% loading. The degree of filler dispersion was quantified and measured using Area Disorder of Delaunay Triangulation mapped onto the filler on binarized MMM images. The results indicate that the magnetized MMM presents a greater degree of dispersion than the unmagnetized MMM.

Magnetorheological (MR) elastomers become one of the most powerful smart and advanced materials that can be tuned reversibly, finely, and quickly in terms of their mechanical and viscoelastic properties by an input magnetic field. They are composite materials in which magnetizable particles are dispersed in solid base elastomers. Their distinctive behaviors are relying on the type and size of dispersed magnetic particles, the type of elastomer matrix, and the type of non-magnetic fillers such as plasticizer, carbon black, and crosslink agent. With these controllable characteristics, they can be applied to various applications such as vibration absorber, isolator, magnetoresistor, and electromagnetic wave absorption. This review provides a summary of the fabrication, properties, and applications of MR elastomers made of various elastomeric materials.

In this study, we experimentally investigated magnetic particle movement in two-phase flow under an external magnetic field. According to Faraday&rsquo, s law, the alignment of a magnet is important for power generation. For high generation, it is important to understand how magnetic particles move in two-phase flow. The rotationality could be determined by observing a single particle, however, this is impossible due to the flow conditions. In this study, we estimated nonrotationality based on the vorticity. To eliminate scattered light and improve the signal-to-noise ratio, the laser-induced fluorescence particle image velocimetry technique was used. The solenoid nozzle has a hydraulic diameter of 3 mm. Its surface is covered with a coil with a diameter of 0.3 mm. The average diameter of a magnetic particle is 1.2 &mu, m. The excitation and emission wavelengths are 532 and 612 nm, respectively. A thin laser sheet setup was configured. The laser sheet was illuminated on both sides to prevent shadows. The images were captured at 200 &mu, m away from the wall and center of the nozzle. To estimate the decrease in vorticity, the theoretical and single-phase non-magnetic and magnetic particles are compared. The vorticity of magnetic particles is reduced by the external magnetic field.

Tissue engineering is a promising strategy for the repair and regeneration of damaged tissues or organs. Biomaterials are one of the most important components in tissue engineering. Recently, magnetic hydrogels, which are fabricated using iron oxide-based particles and different types of hydrogel matrices, are becoming more and more attractive in biomedical applications by taking advantage of their biocompatibility, controlled architectures, and smart response to magnetic field remotely. In this literature review, the aim is to summarize the current development of magnetically sensitive smart hydrogels in tissue engineering, which is of great importance but has not yet been comprehensively viewed.

The need for high-throughput screening has led to the miniaturization of the reaction volume of the chamber in bioassays. As the reactor gets smaller, surface tension dominates the gravitational or inertial force, and mixing efficiency decreases in small-scale reactions. Because passive mixing by simple diffusion in tens of microliter-scale volumes takes a long time, active mixing is needed. Here, we report an efficient micromixing method using magnetically rotating microparticles with patterned magnetization induced by magnetic nanoparticle chains. Because the microparticles have magnetization patterning due to fabrication with magnetic nanoparticle chains, the microparticles can rotate along the external rotating magnetic field, causing micromixing. We validated the reaction efficiency by comparing this micromixing method with other mixing methods such as simple diffusion and the use of a rocking shaker at various working volumes. This method has the potential to be widely utilized in suspension assay technology as an efficient mixing strategy.

The success of cell therapy approaches is greatly dependent on the ability to precisely deliver and monitor transplanted stem cell grafts at treated sites. Iron oxide particles, traditionally used in vivo for magnetic resonance imaging (MRI), have been shown to also represent a safe and efficient in vitro labelling agent for mesenchymal stem cells (MSCs). Here, stem cells were labelled with magnetic particles, and their resulting response to magnetic forces was studied using 2D and 3D models. Labelled cells exhibited magnetic responsiveness, which promoted localised retention and patterned cell seeding when exposed to magnet arrangements in vitro. Directed migration was observed in 2D culture when adherent cells were exposed to a magnetic field, and also when cells were seeded into a 3D gel. Finally, a model of cell injection into the rodent leg was used to test the enhanced localised retention of labelled stem cells when applying magnetic forces, using whole body imaging to confirm the potential use of magnetic particles in strategies seeking to better control cell distribution for in vivo cell delivery.

Magnetorheological (MR) effect is a phenomenon typical of suspensions of magnetizable particles in a liquid carrier, characterized by strong changes of their mechanical properties in response to applied magnetic fields. Its origin is on the migration of magnetized particles and their aggregation into chain-like structures. However, for ferrogels, consisting of dispersions of magnetic particles in a polymer matrix, migration of particles is hindered by the elastic forces of the polymer network, preventing from strong MR effect. Interestingly, we demonstrate in this manuscript that strong MR effect in robustly cross-linked polymer ferrogels is still possible. Experimental results showed enhancement of the storage modulus of more than one order of magnitude for alginate ferrogels containing less than about 10 vol.% of iron particles under moderate magnetic fields. The differential feature of these ferrogels is that, instead of individual particles, the disperse phase consisted of large clusters of iron microparticles homogeneously distributed within the polymer networks. These clusters of magnetic particles were formed at the stage of the preparation of the ferrogels and their presence within the polymer networks had two main consequences. First, the volume fraction of clusters was considerably larger than this of individual particles, resulting in a larger effective volume fraction of solids. Second, since the force of magnetic attraction between magnetic bodies is roughly proportional to the cube of the body size, the existence of such clusters favored inter-cluster interaction under a magnetic field and the appearance of strong MR effect. On this basis, we demonstrated by theoretical modeling that the strong MR effect displayed by the alginate ferrogels of the present work can be quantitatively explained by assuming the existence of large, roughly spherical particle aggregates formed at the stage of the preparation of the ferrogels. Our theoretical model provides a reasonable quantitative prediction of the experimental results, This study was supported by project FIS2017-85954-R (Ministerio de Economía, Industria y Competitividad, MINECO, and Agencia Estatal de Investigación, AEI, Spain, cofunded by Fondo Europeo de Desarrollo Regional, FEDER, European Union). CGV acknowledges financial support by Ministerio de Ciencia, Innovación y Universidades and University of Granada, Spain, for her FPU17/00491 grant. AZ is grateful to the Program of the Ministry of Education and Science of the Russian Federation, projects 02.A03.21.0006, 3.1438.2017/4.6, and 3.5214.2017/6.7 and the Russian Fund of Basic Researches, project 18-08-00178

Diverse polymer crosslinking techniques allow the synthesis of linear polymer-like structures whose monomers are colloidal particles. In the case where all or part of these colloidal particles are magnetic, one can control the behaviour of these supracolloidal polymers, known as magnetic filaments (MFs), by applied magnetic fields. However, the response of MFs strongly depends on the crosslinking procedure. In the present study, we employ Langevin dynamics simulations to investigate the influence of the type of crosslinking and the distribution of magnetic particles within MFs on their response to an external magnetic field. We found that if the rotation of the dipole moment of particles is not coupled to the backbone of the filament, the impact of the magnetic content is strongly decreased., International Conference on Magnetic Fluids - ICMF 2019

Fe3O4/poly(o-anisidine) (POA) magnetic composite nanoparticles with their core-shell structure were synthesized by chemical oxidation polymerization technique and adopted as a magneto-responsive magnetorheological (MR) material. The chemical structure and morphology of core-shell nanoparticles were identified by FT-IR, SEM, TEM, and elemental analyzer. Pycnometer and vibrating sample magnetometer showed that the magnetic saturation and density of the Fe3O4/POA particles were reduced by the POA shell coatings. The rheological properties of the MR suspension dispersed in a silicone oil at various magnetic field strengths were investigated using a rotating rheometer under a magnetic field. The resulting MR suspension showed a typical Newtonian fluid behavior in the absence of external stimuli. When an external magnetic field was applied, it formed a strong chain structure, acting like a solid with a yield stress. Further solid-like behaviors were observed from storage shear relaxation and viscoelastic tests. Finally, the Fe3O4/POA nanoparticles showed better dispersion stability than pure Fe3O4 nanoparticles with 50% improvement.

Supracolloidal magnetic polymers (SMPs) are structures made by crosslinking magnetic particles. In this work, using Langevin dynamics simulations, we study the zero-field magnetic properties of clusters formed in suspensions of SMPs with different topologies -- chains, rings, X and Y -- that interact via Stockmayer potential. We find that the presence of central attraction, resulting in the formation of large compact clusters, leads to a dramatic decrease of the suspension initial susceptibility, independently from SMP topology. However, the largest decrease corresponds to chain-like SMPs with strongly interacting particles. This is due to the higher rotational degrees of freedom of SMPs with such topology, which allows the particles to reorganise themselves inside the clusters in such a way that their magnetic moments form energetically advantageous vortex structures with negligible net magnetic moments., Comment: International Conference on Magnetic Fluids - ICMF 2019

The magnetorheological (MR) elastomer as a hard and soft hybrid functional material, a composite material consisting of magnetic hard particles embedded in elastomeric soft matrix, is a branch of MR materials that are functional smart materials rapidly responding to external magnetic fields. These tunable properties of MR elastomers facilitate a variety of applications. In this brief review paper, in addition to general information on the MR elastomers, recent research not only on a wide variety of MR elastomeric systems focusing on various magnetic particles, elastomeric matrices, additives and particle modification methods, but also on their characteristics including MR properties from dynamic oscillation tests is covered along with their mechanical properties such as the Payne effect, tensile strength and engineering applications.

Microvalves play an important role in fluid control in micro total analysis systems (µTAS). Previous studies have reported complex fabrication processes for making microvalve elements in a channel. Hence, there is a need for a simpler microvalve fabrication method for achieving throughput improvement and cost reduction in µTAS. In this study, we propose a simple fabrication method for a magnetically driven microvalve array using a photosensitive composite. The composite was prepared by mixing a photoresist and magnetic particles of pure iron. The simple fabrication process was performed by using a laminating layer composed of a sacrificial part and the composite in a channel. The microvalve elements were fabricated by one-step photolithography using the processability of the sacrificial layer and composite. Further, we demonstrated the magnetic driving property of the fabricated microvalve array device. Compared to devices containing non-driving microvalves, the flow rate was decreased by 50%, and the pressure difference between the inlet and outlet increased by up to 4 kPa with increase in driving microvalve elements. These results imply that our proposed device could be useful for practical µTAS applications.

A hydrogel is a 3-Dnetwork of polymer chains in which water is the dispersion medium. Hydrogels have found extensive applications inthe biomedical field due to their resemblance to living tissues.Furthermore, hydrogels can be endowedwith exceptionalproperties by addition of syntheticmaterials. For example, magneticfield-sensitive gels, called ferrogels, are obtained by embedding magnetic particles in the polymer network. Novelliving tissueswith unique magnetic field-sensitive propertieswere recently preparedby 3-D cell culture in biocompatible ferrogels. This talk critically reviews the most recent progress and perspectives intheirsynthesis, characterizationand biocompatibility evaluation. Optimizationof ferrogels for this novel applicationrequires low-density, strongly magnetic, multi-domain particles. Interestingly, the rheological properties of the resulting ferrogelsin the absence of field were largely enhanced with respect to nonmagnetic tissues, which can only be explained by the additional cross-linking imparted by the embeddedmagnetic particles.Remarkably, rheological measurements under an applied magnetic fielddemonstrated that magnetic tissuespresented reversibly tunable mechanical properties, which constitutes a unique advantage with respect to nonmagnetic tissues. In vivo evaluation of ferrogelsshowed good biocompatibility, with only some local inflammatoryresponse, and noparticle migrationor damage to distant organs., Financial support: project FIS2013-41821-R (MINECO, Spain; co-funded by ERDF, European Union); project FIS PI14-1343 funded by the Spanish MINECO (Instituto Carlos III), co-funded by the ERDF of the European Union; AZ also acknowledges the Russian Scientific Foundation, project 14-19-00989.

In this study, we have taken the concept of water treatment by functionalized magnetic particles one step forward by integrating the technology into a complete proof of concept, which included the preparation of surface modified beads, their use as highly selective absorbents for heavy metals ions (Zinc, Nickel), and their performance in terms of magnetic separation. The separation characteristics were studied both through experiments and by simulations. The data gathered from these experimental works enabled the elaboration of various scenarios for Life Cycle Analysis (LCA). The LCA showed that the environmental impact of the system is highly dependent on the recovery rate of the magnetic particles. The absolute impact on climate change varied significantly among the scenarios studied and the recovery rates. The results support the hypothesis that chelation specificity, magnetic separation and bead recovery should be optimized to specific targets and applications.

In this work, we study inextensible flows of tangent bimagnetic particles in space. Moreover, we obtain the inextensible flows of electric field by Lorentz equation. Finally, we obtain new results for inextensible flows of tangent bimagnetic particles in space. © 2019 World Scientific Publishing Company.

In this work, we designed a visual biosensor for dopamine (DA) detection using magnetic Fe3O4 particles and dithiobis(sulfosuccinimidylpropionate)-modified gold nanoparticles (DTSSP-AuNPs) as the recognition elements. Specifically, DA molecules were assembled onto the surface of DTSSP-AuNPs via the amine coupling reaction between the amino group of DA and activated carboxyl group of DTSSP. Accordingly, DA-anchored DTSSP-AuNPs were captured by Fe3O4 through the interaction of catechol and iron. In a magnetic field, the formed Fe3O4-DA-DTSSP-AuNPs conjugates were easily removed from the solution, leading to fading of the AuNPs suspension and decrease of the UV/Vis signal. As a result, a detection limit of 10 nM for DA was achieved. The theoretical simplicity and high selectivity demonstrated that the sandwich-type strategy based on Fe3O4 and AuNPs would lead to many colorimetric detection applications in clinical study by rationally designing the surface chemistry of AuNPs and Fe3O4.

According to the magnetic interaction energy of the magnetic particles of magnetorheological fluids, the physics model of magnetic particles was established. The physics mode of a certain number evenly distributed magnetic particles was simulated by using Monte Carlo method. The location changes of magnetic particles were emphatically researched in the magnetic field. The simulation results show that the chain or column structure of magnetic particles was formed along the direction of magnetic line in the external magnetic field. The simulation with experimental results are consistent, thus the effectiveness of the proposed method was preliminarily proved.

Manipulation of micron-size magnetic particles of the superparamagnetic type contributes significantly in many applications like controlling the antibody/antigen binding process in immunoassays. Specifically, more target biomolecules can be attached/tagged and analyzed since the three dimensional structure of the magnetic particles increases the surface to volume ratio. Additionally, such biomolecular-tagged magnetic particles can be easily manipulated by an external magnetic field due to their superparamagnetic behavior. Therefore, magnetic particle- based immunoassays are extensively applied in micro-flow cytometry. The design of a square-loop micro-trap as a magnetic particle manipulator as well as numerical and experimental analysis is presented. Experimental results showed that the micro-trap could successfully trap and concentrate magnetic particles from a large to a small area with a high spatial range.

In this paper, properties of resistance force of a shock absorber using magnetic functional fluids having both micrometer- and nanometer-sized magnetic particles are reported. The resistance force can be controlled by changing strength of the magnetic field applied to the magnetic functional fluid. The resistance force is influenced by the mixture ratio of the micrometer- to the nanometer-sized magnetic particles.

Specific heating of magnetic particles in radiofrequency (RF) capacitive hyperthermia and its hyperthermic effect were investigated in an in vivo study. Magnetite cationic liposomes (MCLs) were injected into a rat tumor on the femur and 8 MHz-RF capacitive heating was applied to the rat under "mild heating" conditions. Although the input power of RF capacitive heating was low under the same power conditions, the MCLs-injected tumor was heated over 43 degrees C, whereas it was only heated to 41 degrees C in the case of the rats not injected with MCLs. A necrotic area in the tumor was observed in the heated rats. From the results of histological observation of the removed tissue, the necrotic area in the MCLs-injected tumor was wider than that in MCLs-free tumor. Complete tumor suppression was observed in 71% (5 / 7) of MCLs-injected rats, and the hyperthermic effect was greatly improved by the MCLs.

By implementing the magneto-Cosserat continuum theory in FEM scheme, it is possible to simulate magnetic alignment in powders with magnetic anisotropy during compaction in an applied magnetic field. We thereby analyze the relationship between the direction of magnetic field and compaction process, such as cross compaction and parallel compaction. The rotation of the axes is thus calculated at various conditions of applied magnetic field. In our previous study, Cosserat constant /spl beta/ was given arbitrarily. The method to calculate the Cosserat constant /spl beta/ is proposed and its effect on the rotation of the particles' easy axes is discussed. As a demonstration of the developed method, magnetic particles' alignment during compaction in an applied magnetic field is simulated. The calculated results are in good agreement with the experimental ones.

The microwave permeability of composites made of ferrite particles in a non-magnetic matrix is affected by particle shape and size. To account for the second effect, we have developed a micromagnetic model for calculating the microwave polarizability of a particle with non-uniform magnetization. This model is described in detail: a generalized demagnetizing operator associated with the equilibrium magnetic configuration inside the particle is introduced; the polarizability is defined as the perturbation of this configuration by the external magnetic excitation; the permeability of a macroscopic sample is calculated using a space averaging procedure. The numerical methods are introduced and results for two systems are discussed: domain modes in thin films and ferrite composites with planar anisotropy.

Separation of magnetic particles in sand processing is very important for many industrial purposes. This paper presents an automation process to separate the magnetic particles from a non-homogeneous solid-solid mixture (sea sand). Here a magnetic force is created by changing the electric field and thus the particles are separated from the mixture of sand automatically. Here such a simple and cost effective design is prsented which can automatically take the the mixture as input and give the refined and separated product as output continuously. ABSTRAK : Pengasingan zarah-zarah bermagnet dalam pemprosesan pasir penting untuk pelbagai tujuan industri. Kertas ini membentangkan proses pengautomatikan untuk mengasingkan butir-butir bermagnet dari pepejal tak homogen - campuran pepejal (pasir pantai). Di sini, daya magnet dihasilkan dengan menukarkan medan elektrik dan seterusnya butir-butir ini terasing daripada campuran pasir dengan sendirinya. Kaedah yang mudah dan rekaan keberkesanan kos ini secara langsung mengambil campuran tersebut sebagai input dan memberikan hasil bertapis dan terpisah sebagai output dengan berterusan.

A bubble cell capillary classically used to extend the optical path length for UV-vis detection is employed here to trap magnetic beads. With this system, a large amount of beads can be captured without inducing a strong pressure drop, as it is the case with magnetic beads trapped in a standard capillary, thereby having less effect on the experimental conditions. Using numerical simulations and microscopic visualizations, the capture of beads inside a bubble cell was investigated with two magnet configurations. Pressure-driven and electro-osmotic flow velocities were measured for different amounts of protein-A-coated beads or C18-functionalized beads (RPC-18). Solid-phase extraction of a model antibody on protein-A beads and preconcentration of fluorescein on RPC-18 beads were performed as proof of concept experiments. Figure Isovalues of the magnetic induction produced by two permanent magnets in attraction configuration with a capillary placed between them

This paper presents a discussion of the properties and the behavior of an unit magnetic particle as calculated by the DPC (Della Torre, Pinzaglia and Cardelli) model. The general mathematical expressions of the vector field generated by the unit magnetic particle are derived in a special regular parametric coordinates system. It is shown that, in a special case, the DPC model leads to the same results as in the Stoner-Wohlfarth dealing with the physics of an ellipsoidal, single-domain, uniaxial magnetic particle. Some numerical examples for a possible use of the DPC model in the analysis of nanomagnetic samples are presented.

Magnetic particles (magnetite) were used to make radiofrequency (RF) capacitive hyperthermia effective to a specific site. In an agar phantom experiment, a magnetite-containing agar piece was buried in a large agar phantom and heated by an 8 MHz-RF capacitive heating device. The magnetite-containing agar piece was heated more than the magnetite-free agar phantom, and the specific adsorption rate in the phantom was increased 1.5 times by the magnetite particles. The temperature distribution in the large agar phantom showed that the highest temperature was obtained at the center of the magnetite-containing piece. The rate of temperature increase was approximately proportional to the magnetite concentration to the power 0.8. This method was applied to an in vivo experiment using a pig. Magnetite was prepared as a colloidal material dispersed in a carboxymethylcellulose solution (CMC-Mag) and intramuscularly injected in the pig femur. As a result of 8 MHz-RF heating, the temperature at the CMC-Mag-injected point increased to over 43 degrees C after 7 min, while the temperature at a point without magnetite was under 40 degrees C at the same time. The specific adsorption rate in the magnetite-containing tissue was twice that of the magnetite-free tissue. In addition, the time required to reach a temperature of over 43 degrees C was only 7 min, while it was over 15 min in the case without the CMC-Mag.

The final publication is available at Springer via http://dx.doi.org/10.1007/s10921-015-0309-5 An innovative NDT technique is proposed for surface inspection of materials not necessarily magnetic or conductive, based on local magnetic field variations due to ferrofluid deposited in the cracks. The feasibility of the technique is assessed preliminarily, based on signal detectability without applied external magnetic field, and under applied DC fields. The signals (local magnetic flux density variations) are quantified analytically, experimentally and numerically. The model agrees well with the tests, showing that the signal increases with the applied field strength, up to the saturation magnetization of the ferrofluid, and decreases with the distance to the crack longitudinal axis, and thus it can provide useful estimations of the signal. The proposed technique, requiring application of external fields to magnetize the ferrofluid to enhance the signal, seems promising: the model suggests that signals associated to cracks significantly smaller than surface cracks in a target application like aircraft skin panel inspection NASA STD-5009 are easily detectable with commercial magnetometers.