Papers by Keyword: Magnetic Particle

Abstract: Ferrofluids are colloidal mixtures which consist of nanosized magnetic particles suspended in a base fluid. The typical magnetic particles could be maghemite, magnetite or cobalt ferrite etc. To keep a ferrofluid suspension in a stable state is possible by an electrical double layer or by adding surfactant. They have many applications on electrical, mechanical and optical systems. Recently, the ability of being manipulated by an external magnetic field made them considerable for microfluidic systems such as micro operations, pumping and mixing. Among them, micro scaled pumping systems have appeared as a critical research area due to its notable potential to be applied on many biological and electronic systems. Moreover, the development of lab on a chip and the micro total analysis systems for biological issues has revealed the necessity of liquid transport for micro quantities. Micropumps with ferrofluid plug actuation mechanisms are considered to have the ability to fulfill this requirement. Therefore, driving the working fluids with ferrofluid plugs in a micro-sized tube or channel has attracted researchers’ interest. In this study, ferrofluid plug actuated micro pumping systems have been reviewed from the available literature based on their design and their maximum generated flow rate.

Abstract: Behaviors of both micrometer-size nonmagnetic abrasive particles and micrometer-size magnetic particles in a magnetic fluid are investigated by using the discrete particle method which is based on the simplified Stokes dynamics. Sheet-like clusters of nonmagnetic particles and sheet-like clusters of magnetic particles alternately appear one after another in the axis direction when the flow velocity is small.

Abstract: Behavior of both suspended micrometer-size magnetic particles and micrometer-size nonmagnetic abrasive particles in a micro-tube filled with a magnetic compound fluid is investigated by using discrete particles method based on the simplified Stokesian dynamics in order to reveal the polishing process of inner surface of the tube with an axial flow. Giving the axial flow of the appropriate velocity is effective on performing uniform polishing of the surface in the magnetic compound fluid polishing.

Abstract: In the paper, magnetic flocculation was used in high turbidity mine water treatment. The results show that the magnetic flocculation is one of efficient methods in removing the COD and SS of high turbidity mine water. It finds the optimal conditions: the PAFC was 30mg/L and added with the fast stirring speed being 250r/min for 2min; then, 50mg/L magnetic particle was added with slow stirring speed staying 50r/min for 7min. The wastewater is treated under the optimal condition, the removal efficiency of SS and COD reached 94% and 71% respectively.

Abstract: Shape memory polymers are stimuli-responsive materials able to adaptively store a temporary (deformed) shape and recover a ‘memorized’ permanent shape under an external stimulus. In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature, Tswitch. If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from NdFeB magnetic particles and crosslinked low density polyethylene (XLDPE) shape memory nanocomposite containing 2 wt% nanoclay is introduced. Various amounts of NdFeB particles (5, 15, 40 wt %) were added to the nanocomposite. Electromagnetically triggered shape memory properties of the formed composites were conducted using an alternative magnetic field with a frequency of 9 kHz and strength of 15 kW. The shape recovery of samples was possible by inductive heating and the shape recovery rates comparable to those obtained by conventional heating methods were demonstrated. It was concluded that the maximum heat generation achievable by inductive heating in the alternative magnetic field depends on magnetic particle content. The sample containing 15wt% NdFeB reached a full shape recovery of 25% extension within 6 minutes remaining in the magnetic field.

Abstract: . Aqueous suspensions containing small magnetic particles have been increasingly used in biosciences and biotechnology. Magnetic particles develop magnetic polarization and magnetophoretic mobility, and because of such unique properties, these carriers may be eligible candidates for delivering drugs to specific sites within the body. Their special properties also allow other uses, such as those in embolization, radioisotope delivery, magnetic cell tracking for monitoring cell therapy, magnetofection, and hyperthermia. This review focuses on a discussion about magnetic particles, the properties and fate of magnetic carriers, the methods used to produce and characterize them, and their other uses in biotechnology.

Abstract: In this paper, we first analyzed the nano-magnetic fluid composition and properties. Then we studied the characteristics of nano-magnetic fluid magnetization and magnetization mechanism. In addition, we also studied the nano-Fe3O4 magnetic particle size and surface modification effect on the magnetic properties of magnetic fluids. Nano-magnetic fluid is a new type of liquid nano-composite functional material. It also has magnetism and mobility, and therefore it has many unique properties and a wide range of applications. Nano-magnetic fluid magnetization characteristic is one of its main properties, its performance and application of magnetic fluid play a decisive role.

Abstract: Functionally Graded Material (FGM) is a characteristic material having many functions and possibilities. The improvement of the long term stability is strongly necessitated by railway polymeric materials. To carry out the purpose, FGM is an expected material that enables to improve the certain properties and affinities. The authors tried to produce a graded compound of the magnetic particles in the polymer matrix in the magnetic field. From the results, the graded compound of the magnetic particles was produced by the control of magnetic flux. In particular, the control of time during which the magnetic field was charged was effective to improve the dispersion state of the magnetic particles in polymer matrix.

Abstract: This paper proposes a new magnetic field assisted machining process using a magnetic machining jig (permanent magnet tool) to finish the internal surface of thick tubing 5~30 mm in thickness. Because the magnetic machining jig consists of permanent magnets, it can generate a higher magnetic force (finishing force) than conventional magnetic abrasives, and makes possible the internal finishing of thick non-ferromagnetic tubing. First, the principle and the feature of this process were examined. It was compared that the difference of the mechanism of using the conventional magnetic abrasives and magnetic machining jig (magnet tool) was clarified. Next, a processing unit and magnetic machining jig were made, and the processing unit was set on a lathe machine. An experiment was performed on a thick SUS304 stainless steel tubing 5 mm in thickness. In this study, it was clarified that this processing method can improve the roundness of the inside tubing while improving the surface roughness. The results showed that the initial surface roughness of 6.5 μm Ra can be improved to 0.06 μm Ra, and the roundness of the inside tubing can be improved from 187 μm to 89 μm.

Abstract: Composition, synthesis and structural properties of ferrofluids and magnetorheological fluids are reviewed and compared. The similarities and main differences between the two types of magnetically controllable fluids are outlined and exemplified in the paper. Chemical synthesis and structural characterization of magnetizable fluids for engineering and biomedical applications are thoroughly discussed.