Concentration Of Magnetic Particles Research Articles

Multimodal Locomotion and Dynamic Interaction of Hydrogel Microdisks at the Air-Water Interface under Magnetic and Light Stimuli.

The potential applications of hydrogel microrobots in biomedicine and environmental exploration have sparked significant interest in understanding their behavior under multiphysical fields. This study explores the multimodal locomotion and dynamic interaction of hydrogel microrobots at the air-water interface under magnetic and light stimuli. A pair of hydrogel microrobots at the air-water interface exhibits a transition from cooperative, combined rotation to interactive behavior, involving both rotation and revolution under the influence of a rotating magnetic field (RMF), and a shift from attraction to separation under near-infrared (NIR) light, demonstrating the dynamic modulation of their behaviors in response to different stimuli. Notably, the behavioral patterns of multiple hydrogel microrobots under multiphysical fields indicate that NIR light can enhance interactive motion behaviors under RMFs and extend the range of motion trajectories. Dynamic models for each condition are established and analyzed based on dynamic equilibrium, and their behavior can be modulated by parameters such as magnetic particle concentration, magnetic field frequency, and NIR light intensity. This work introduces a novel strategy for regulating and controlling the dynamic behaviors of hydrogel microrobots, offering new insights into their multiphysical field locomotion.

An innovative 4D printing approach for fabrication of anisotropic collagen scaffolds

Collagen anisotropy is known to provide the essential topographical cues to guide tissue-specific cell function. Recent work has shown that extrusion-based printing using collagenous inks yield 3D scaffolds with high geometric precision and print fidelity. However, these scaffolds lack collagen anisotropy. In this study, extrusion-based 3D printing was combined with a magnetic alignment approach in an innovative 4D printing scheme to generate 3D collagen scaffolds with high degree of collagen anisotropy. Specifically, the 4D printing process parameters-collagen (Col):xanthan gum (XG) ratio (Col:XG; 1:1, 4:1, 9:1 v/v), streptavidin-coated magnetic particle concentration (SMP; 0, 0.2, 0.4 mg ml-1), and print flow speed (2, 3 mm s-1)-were modulated and the effects of these parameters on rheological properties, print fidelity, and collagen alignment were assessed. Further, the effects of collagen anisotropy on human mesenchymal stem cell (hMSC) morphology, orientation, metabolic activity, and ligamentous differentiation were investigated. Results showed that increasing the XG composition (Col:XG 1:1) enhanced ink viscosity and yielded scaffolds with good print fidelity but poor collagen alignment. On the other hand, use of inks with lower XG composition (Col:XG 4:1 and 9:1) together with 0.4 mg ml-1SMP concentration yielded scaffolds with high degree of collagen alignment albeit with suboptimal print fidelity. Modulating the print flow speed conditions (2 mm s-1) with 4:1 Col:XG inks and 0.4 mg ml-1SMP resulted in improved print fidelity of the collagen scaffolds while retaining high level of collagen anisotropy. Cell studies revealed hMSCs orient uniformly on aligned collagen scaffolds. More importantly, collagen anisotropy was found to trigger tendon or ligament-like differentiation of hMSCs. Together, these results suggest that 4D printing is a viable strategy to generate anisotropic collagen scaffolds with significant potential for use in tendon and ligament tissue engineering applications.

On the dependence of the thermal module of elasticity of a two-component magnetic fluid on frequency, concentration and magnetic field

Purpose. Study of the dependence of the thermal modulus of elasticity of a two-component magnetic fluid on the magnitude of the magnetic field strength, the frequency of external disturbance and the volumetric concentration of magnetic particles.Method. The research method is based on the kinetic theory of liquid systems. Based on previously constructed kinetic equations for one-particle and two-particle distribution functions and a microscopic expression for the heat flux vector, an explicit dynamic expression for the thermal modulus of elasticity of magnetic fluids is obtained. In fast processes in liquids, heat transfer occurs in waves and their propagation is similar to the propagation of second sound in helium II. The thermal modulus of elasticity in liquids appears at high frequencies and ensures the propagation of second sound. The expression for the thermal modulus of elasticity consists of potential and kinetic parts, taking into account structural and translational relaxation processes, respectively. To study the thermoelastic properties of magnetic fluids, appropriate expressions of potential interaction energies were selected for each subsystem, allowing for numerical calculations.Results. Numerical calculations of the frequency and concentration dependence of the dynamic thermal modulus of elasticity in the presence of an external magnetic field in a kerosene-based magnetic fluid were carried out. The calculation results show that an increase in the influence of external disturbances leads to a nonlinear increase in the thermal modulus of elasticity in the magnetic fluid. An increase in the volume concentration of magnetic particles and an increase in the magnetic field strength also led to a nonlinear increase in the thermal modulus of elasticity in the magnetic fluid.Conclusion. It has been established that, due to taking into account translational and structural relaxation processes, the region of frequency dispersion of the thermal elastic modulus is wide. Numerical calculations carried out at different values of the external magnetic field and the volume concentration of magnetic particles showed that although an increase in the magnetic field and concentration of magnetic particles leads to an increase in the thermal modulus of elasticity, their increase does not affect the change in the frequency dispersion region.

Online detection method for magnetic suspension concentration based on machine vision

Abstract With the intelligent development of magnetic particle inspection, the quality of magnetic indications formed at cracks is closely related to the accuracy of magnetic particle inspection image analysis results. The concentration of magnetic suspension is a key process parameter affecting the quality of magnetic indication formation. Hence, this study presents an online detection method based on machine vision for measuring magnetic suspension concentration. The method initially enhances the contrast of images of the pear-shaped measuring tube containing magnetic suspension and then extracts scale lines through feature analysis and morphological processing. A method for extracting the magnetic particle sedimentation area of magnetic suspension based on a dual-threshold segmentation algorithm is proposed. The contour filtering algorithm and pixel calibration method are used to obtain the magnetic particle concentration of the non-estimation and estimation areas based on scale line extraction, ultimately forming an online accurate detection method for magnetic suspension concentration values. Experiments were conducted to validate the method against different concentrations, turbidity levels, tilting angles of the pear-shaped measuring tube, and ambient brightness. The results show that the error in magnetic suspension concentration detection based on this method is within ±3%. This has certain reference value for the stable control of magnetic suspension concentration and for enhancing the reliability of intelligent decision-making results in magnetic particle inspection.

Integrated 3D printing of reconfigurable soft machines with magnetically actuated crease-assisted pixelated structures

Reconfigurable magnetic soft machines have a wide range of applications in soft robotics, aerospace, medical devices and flexible electronics. However, the high-precision reconfiguration of magnetically actuated soft machines is hindered by the absence of rational structural design and integrated manufacturing techniques. Here, we report an innovative design and manufacturing approach to realize magnetically actuated high-precision reconfigurability. We present a crease-assisted pixelated design using a mixture of magnetic particles and phase-change medium as the pixel points, with an elastomer as the crease to connect the pixel points, simulating origami. The design of elastomer creases improves pixel stiffness without loss of reconfigurable accuracy, thereby significantly improves the magnetic particle concentration in the pixel. An effective multi-material 3D printing technique is used to achieve the integrated printing of the designed structure. The resulting magnetically actuated soft machines exhibit remarkable capabilities, achieving small curvature bending and precise reconfiguration with weaker actuating magnetic fields (100mT). The superior performance of this design has been confirmed through demonstrations of crawling and rolling machines, magnetically controlled switches, and logic circuits. The work enhances the reconfiguration accuracy of magnetically actuated soft machines, increasing their potential for soft robotics and flexible electronics applications.

Ferrite doped sucrose-derived porous carbon composites inspired by Pharaoh's Serpent for broadband electromagnetic wave absorption

This paper presents a straightforward and intriguing approach for designing wide bandwidth, lightweight, and tunable electromagnetic wave (EMW) absorbing materials. Drawing inspiration from the "Pharaoh's Snake", biomass carbon source and sucrose were used to fabricate Fe/Fe3O4@porous carbon (PC) composite materials through combustion experiments. Subsequently, high-temperature calcination was applied to enhance the microwave absorbing properties of the materials. The as-prepared composites demonstrate an impressive 6.62 GHz effective bandwidth and an excellent absorption ability of −51.54 dB at a matched thickness of 2.2 mm. Moreover, by tuning the content of magnetic particles and controlling the thickness of the composite material, comprehensive coverage across C, X, and Ku bands can be achieved. The outstanding performance suggests that the synthesized Fe/Fe3O4@PC porous materials hold significant potential for applications in electromagnetic wave absorption. It opens up a novel, straightforward, and cost-effective approach to acquiring broadband absorbing materials.

Rapid Measurement of Magnetic Particle Concentrations in Wildland–Urban Interface Fire Ashes and Runoff Using Compact NMR

Wildfires are increasing in size, frequency, and intensity, releasing increased amounts of contaminants, including magnetic particles, into the surrounding environment. The aim of this paper is to develop a sensing method for the detection and quantification of magnetic particles (MPs) in fire ash and fire runoff using a compact Time-Domain Nuclear Magnetic Resonance (TD-NMR) system. The system is made up of custom NMR electronics with a compact and rugged permanent magnet array designed to enable future deployment as an in situ sensor. A signal-to-noise ratio of 25 dB was measured for a single scan, and sufficient data can be acquired in one minute. A linear relationship with an R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> value of 0.9699 was established between transverse relaxation rates and MP concentrations in ash samples. This was validated by testing known dilutions of pure magnetite particles and showing that they fit within the same linear curve. The developed approach was then applied to detect MPs in surface water, where changes in the relaxation rates as high as 400% were observed before and after a wildfire event. MPs were removed from the surface water using a magnetic particle separator to confirm that observed changes were solely due to the presence of MPs. The compact NMR system can be used as a simple and rapid approach to track and quantify the concentrations of magnetic particles released from fire ashes and also from other sources such as discharges from coal ash and other combustion ashes.

Immobilized cold-active enzymes onto magnetic chitosan microparticles as a highly stable and reusable carrier for p-xylene biodegradation

Stability and reusability properties are the two most important factors that determine an enzyme’s application in industry. To this end, cold-active crude enzymes from a psychrophile (xylene monooxygenase (XMO) and catechol 1,2-dioxygenase (C1,2D) were immobilized on magnetic chitosan microparticles for the first-time using glutaraldehyde as a linker. The potential application of enzyme-loaded magnetic particles to remove and detoxify dissolved p-xylene from water confirmed the synergistic mechanism of degradation for in-situ bioremediation in soil and water. Immobilization was optimized based on four variables, such as magnetic particle (MPs), chitosan, glutaraldehyde, and enzyme concentrations. The immobilized enzymes were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The immobilized enzymes showed improved pH tolerance ranging from 4.0 to 9.0, better temperature stability ranging from 5 to 50, higher storage stability (∼70% activity after 30 days of storage), and more importantly, reusability (∼40% activity after 10 repetitive cycles of usage) compared to their free form. Also, the immobilization of enzymes increased the effectiveness of the enzymatic treatment of p-xylene in soil (10,000 mg/kg) and water (200 mg/L) samples. As a result of the superior catalytic properties of immobilized XMO and C1,2D, they offer great potential for in situ or ex-situ bioremediation of pollutants in soil or water.

Magnetic field-assisted manufacturing of groove-structured flexible actuators with enhanced performance

Magnetic flexible actuators with hard-magnetic particles (NdFeB) as inlays have attracted widespread attention due to their small size, wireless control capability, and diverse transformation modes. The manufacturing method of these actuators plays a crucial role in their functionality. Here we propose a magnetic field-assisted manufacturing method based on vat photopolymerization (VPP) to produce hard-magnetic flexible actuators with 3D architecture in both geometry structure and magnetization arrangements. The assisting magnetic field enables alignment of hard magnetic particles during manufacturing process, thus obtaining a magnetization arrangement. The VPP method offers the ability to manufacture fine structures and selective curing but has a limitation on the magnetic particle content. To deal with the lack of driving force due to the low available content of magnetic particles, we construct groove structure to enhance the actuators' deformation, which is confirmed by both theoretical and experimental analyses. Flexible actuators with a low magnetic particle content (10 wt%) can be fabricated and fulfill intended functionality. We demonstrate the effectiveness of our method by manufacturing multi-arm grippers, showcasing their transportation capabilities. Moreover, we construct a 2-DOF joint for a crawling robot, significantly improving its motion performance and increasing the average step length to 6.8 times. Finally, we design and manufacture a magnetic diaphragm with complex structure and 3D magnetization arrangements, which is applied to a micro pump, demonstrating its pumping process with a rate of about 3.6 mL/min. These results highlight the potential of the proposed method in designing complex structures and magnetization arrangements of flexible actuators, expanding their functional boundaries.

Magnetic-assisted preparation and performance control of Fe3O4/PVDF gradient magnetic composites.

In this study, a gradient Fe3O4/PVDF magnetic composite was prepared using magnetic-assisted template filling technology. The purpose of this study was to explore a simple, economical, and scalable method for preparing gradient magnetic composites. The structure and magnetic performance of the composite were studied, and the parameters that influenced the gradient magnetic properties of the material, such as magnetic intensity, magnet spacing, initial content of magnetic particles, and magnet movement speed, were investigated. The results showed that increasing magnetic intensity during the template filling process enhanced the electromagnetic force on the magnetic particles, resulting in a greater magnetic particle content gradient. The variation in magnet spacing affected the spatial magnetic field distribution, and increasing the magnet spacing increased the gradient of the magnetic intensity in the y-direction. The magnetic gradient of the Fe3O4/PVDF composite first decreased and then increased as the magnet spacing increased. Increasing the magnet movement speed enhanced the gradient of the magnetic intensity in the y-component but shortened the duration of the electromagnetic force. By adjusting these parameters, it is possible to regulate the structural and magnetic properties of the Fe3O4/PVDF composite. This work may have implications for research and application in related fields and promote the development and innovation of magnetic materials.

Imparting anisotropic performance to soft materials via a magnetically-driven programmable templating-deposition strategy

Creating biomimetic aligned structures in soft materials with fast stimuli-responsive ability and tunable performance is of great interest to intelligent material science. However, there is still a technical challenge to balance the relative velocities of polymeric gelation and nano-alignment/accumulation processes in a controllable manner. Herein, a magnetically-driven programmable templating-deposition strategy coupled with an oscillating electrical signal has been developed to impart tunable anisotropic performance to the soft hydrogels. Specifically, the programmable electrophoretic deposition was initiated from a typical self-aggregated chitosan/Fe3O4 nanoclusters in the presence of an external magnetic field, in which case allows magnetically-driven fast templating of chitosan chains to the electrode surface, oriented/enriched nanoclusters into a compact “fiber-like” aligned structure, and then locked by the electric-field induced localized neutralization processes. An oscillating electrical signal has been used for the first time to manipulate the fiber thickness by varying the ON-OFF electrical signal sequences (e.g., each interruption provides extratimes/chances for nano-assembly), resulting in a higher concentration of magnetic particles and tunable aligned structure to the hydrogels with improved multi-functionalities (e.g., mechanical strength, conductivity, magnetic responsiveness, and photothermal activity). The proof-of-concept for potential applications in the controlled drug delivery system and smart magnetic catheter have also been demonstrated. Consequently, this versatile magnetically-driven programmable templating-deposition approach expands the range of stimuli-responsive materials beyond magnetic hydrogels, inspiring the creation of advanced functional soft materials and devices for wide-broad applications.

The Influence of Viscosity on Heat Dissipation under Conditions of the High-Frequency Oscillating Magnetic Field

High-frequency components such as microprocessors, transistors, antennas, voltage-controlled oscillators, and many others generate a large amount of heat. In the absence of satisfactory cooling, these components may suffer damage or even destruction. Therefore, it is important to find effective ways to cool these components. A possible solution is to use oil-based magnetic fluids. Magnetic fluids contain magnetic particles dispersed in oil, and their properties, including viscosity, affect their cooling capabilities. Viscosity can be changed by adding various additives or by adjusting the concentration of magnetic particles. The advantage of using oil-based magnetic fluids for cooling is that they allow for precise dosing and control of the amount of fluid applied to the component, reducing thermal losses and increasing cooling efficiency. In addition, oil-based magnetic fluids can also act as a dielectric, reducing electrical noise and increasing electromagnetic compatibility with the components. Analyzing the heating rate of magnetic fluids consisting of mineral oils in an alternating magnetic field with a frequency of 500 kHz, we have shown the capability of controlling thermal losses by adjusting the viscosity of the carrier liquid.

Magnetically Induced Grid Structure for Enhancing the Performance of a Dual-Mode Flexible Sensor with Tactile/Touchless Perception.

As an advanced sensing technology, dual-mode flexible sensing, integrating both tactile and touchless perception, propels numerous intelligent devices toward a more practical and efficient direction. The ability to incorporate multiple sensing modes and accurately distinguish them in real time has become crucial for technological advancements. Here, we proposed a dual-mode sensing system (B-MIGS) consisting of a dual-layer sensing device with a magnetically induced grid structure and a testing device. The system was capable of utilizing mechanical pressure to perceive tactile stimulation and magnetic sensing to simultaneously transduce touchless stimulation simultaneously. By leveraging the triboelectric effect, the decoupling of tactile and touchless signals in the presence of unknown signal sources was achieved. Additionally, the sensing characteristics of the B-MIGS were optimized by varying the curing magnetic induction intensity and magnetic particle concentration. The influence of the temperature and humidity on the sensing signals was also discussed. Finally, the practical value of the B-MIGS as a dual-mode monitoring system was demonstrated on soft petals and sensor arrays, along with exploration of its potential application in underwater environments.

Magnetic field dependent thermal conductivity investigation of water based Fe3O4/CNT and Fe3O4/graphene magnetic hybrid nanofluids using a Helmholtz coil system setup

Magnetic hybrid nanofluids are making a name of themselves in mainstream application areas such as heat transfer, solar systems, acoustic applications, etc. These nanofluids are highly favorable as their ability to advance the properties of their constituent particles such as their thermophysical properties. This study aims to investigate the magnetic field dependent thermal conductivity of Fe3O4/CNT – water and Fe3O4/Graphene – water magnetic hybrid nanofluids. The thermal conductivity investigations are carried out with the 3ω method under a uniform magnetic field generated by a 3D Helmholtz coil system. Fe3O4/CNT – water and Fe3O4/Graphene – water magnetic hybrid nanofluids were purchased commercially as 20 wt% colloids. Then, the samples with 1, 2, 3, 4, and 5 wt% were prepared by diluting them with DI water. Thermal conductivity measurements were carried out for the samples under the external uniform magnetic field in the range of 0–250 G in both parallel and perpendicular directions to the temperature gradient generated by the thermal conductivity measurement probe. The results pointed out that the thermal conductivity of the samples increases as the magnetic field and particle concentration increase for both magnetic hybrid nanofluids. Additionally, it is obtained that the thermal conductivity enhancement of Fe3O4/Graphene – water is up to 3 times higher than Fe3O4/CNT – water samples. Moreover, the maximum thermal conductivity enhancement was observed as ∼12 % and ∼9 % for Fe3O4/CNT – water, and ∼51 % and ∼21 % Fe3O4/Graphene – water under external magnetic field application with parallel and perpendicular direction, respectively.

Structure-property-actuation relationships of shape-fixable magnetic vitrimer micropillar arrays

Magnetic actuation of micropillar arrays has been exploited for contactless and programmable deformation according to pre-programmed alignment of magnetic particles within the micropillars. However, once the external magnetic field is removed, the magnetically deformed structure reverts to its initial state. Herein, we synthesized magnetic vitrimer composites as micropillar arrays capable of shape fixation via dynamic covalent bonds. In the magnetic vitrimer composites, we systematically varied the concentration of magnetic particles and evaluated their structure-property-performance relationships. An increase in the concentration of the magnetic particles increases both magnetization and modulus of the composites. Although a higher magnetization of the composites will enhance magnetic responsivity, a larger modulus represents a higher bending stiffness, reducing the deformation strain by magnetic actuation. Due to this trade-off relationship, the magnetic actuation of the micropillars is determined by two variables. In competition between two variables, embedding 20 vol% of magnetic particles achieves the maximum bending angle of 45° for the micropillars. By understanding the structure-property relationships, we can optimize the concentration of magnetic particles for a high magnetic responsivity of the shape-fixable micropillar arrays.

Abstract 12321: Discordant Association of Nonalcoholic Fatty Liver Disease With Lipoprotein(a) and Markers of Atherogenic Dyslipidemia

Background: Nonalcoholic fatty liver disease (NAFLD) is associated with atherogenic dyslipidemia and an increased risk of cardiovascular events. Previous studies have suggested a paradoxical inverse relationship between NAFLD severity and Lp(a) level, an independent cardiovascular risk factor. However, contemporary data in patients with biopsy-proven NAFLD in the U.S. are lacking. Hypothesis: NAFLD severity on liver biopsy has a discordant association with Lp(a) and other markers of atherogenic dyslipidemia. Methods: Lp(a), traditional lipid profile, apolipoproteins, and nuclear magnetic resonance-based lipoprotein particle concentration were measured in 151 patients with NAFLD. Levels were compared between those with nonalcoholic fatty liver (NAFL) on histology and non-alcoholic steatohepatitis (NASH), the clinically aggressive NAFLD variant. Results: Median age was 55 [48, 62] years, 67% of patients were women, 83% were White, 43% had NAFL, and 57% had NASH. Demographic characteristics were similar among those with NAFL and NASH. Triglyceride level was higher and High-Density Lipoprotein-cholesterol (HDL-C) was lower among those with NASH as compared with NAFL. Circulating concentration of two key markers of atherogenic dyslipidemia, Apolipoprotein-B (apoB) and Low-Density Lipoprotein particle concentration (LDL-P) was 9% and 17% higher in the NASH group as compared with NAFL, respectively. Contrastingly, Lp(a) concentration was 50% lower in NASH relative to NAFL group (Figure). Hepatocyte ballooning, lobular inflammation, and fibrosis on histology were inversely associated with Lp(a) concentration, while steatosis severity was not. Conclusions: NAFLD severity has a discordant association with Lp(a) and markers of atherogenic dyslipidemia. The mechanistic basis of this relationship may have implications for prognosticating cardiovascular disease risk and determining the safety of targeted Lp(a) lowering in patients with NAFLD.

Discordant association of nonalcoholic fatty liver disease with lipoprotein(a) and markers of atherogenic dyslipidemia

Nonalcoholic fatty liver disease (NAFLD) is associated with atherogenic dyslipidemia and an increased risk of cardiovascular events. Previous studies have suggested an inverse relationship between NAFLD severity and lipoprotein(a) [Lp(a)] level, but contemporary data from the U.S. are lacking. Lp(a), lipid profile, apolipoproteins, and nuclear magnetic resonance-based lipoprotein particle concentrations were measured in 151 patients with biopsy-proven NAFLD. Levels were compared between those with nonalcoholic fatty liver (NAFL) on histology and non-alcoholic steatohepatitis (NASH). Median age was 55 [48, 62] years, 67% of patients were women, 83% were White, 43% had NAFL, and 57% had NASH. Triglyceride level was higher and high-density lipoprotein-cholesterol (HDL-C) was lower among those with NASH as compared with NAFL. Circulating apolipoprotein-B (ApoB) and low-density lipoprotein particle concentration (LDL-P) were 9% and 17% higher in the NASH group as compared with NAFL, respectively. Contrastingly, Lp(a) concentration was 50% lower in NASH relative to NAFL group. Hepatocyte ballooning, lobular inflammation, and fibrosis on histology were inversely associated with Lp(a) concentration. NAFLD severity has a discordant association with Lp(a) and other markers of atherogenic dyslipidemia. This relationship may have implications for prognosticating cardiovascular disease risk in patients with NAFLD.

Experimental investigation on the ferrofluid flow in a horizontal mini channel under the constant magnetic field using PIV

Applying the magnetic field alters the flow characteristics of the ferrofluids, chiefly accounting for heat transfer augmentation. To elucidate how changes in flow characteristics enhance heat transfer, the impact of a constant magnetic field on the laminar ferrofluid (Fe3O4/water nanofluid) flow inside a mini channel is visualized and quantitatively investigated through the PIV method. Experiments are accomplished at the magnetic flux density of 3200 G and the magnetic particle concentration of 0.0014 wt% for 0.30≤Re≤62.5. The effects of the magnetic field are scrutinized on the flow patterns and velocity profiles. The results indicate that at Re=0.30, the region of influence of the magnet is considerable, inducing a y-velocity component, which accelerates the fluid and improves heat transfer. At Re=31.5, two quasi-symmetrical recirculation zones are observed, enhancing the fluid mixing. Additionally, though diminishing the magnetic field effects, raising the Re number from 31.5 to 62.5 increases the overall vorticity magnitude by 45.5%.

Study on the Preparation and Heat Transfer Characteristics of Temperature Sensitive Magnetic Fluid

Water-based temperature sensitive magnetic fluid and kerosene-based temperature sensitive magnetic fluid are prepared by using chemical co-precipitation method. The effects of magnetic particle concentration, magnetic field strength, and temperature on its thermal conductivity and viscosity were Studied. The results show that the thermal conductivity of the fluid is greatly increased by addition of magnetic particles. The thermal conductivity of water-based magnetic fluid with a concentration of 10% is increased 27.3% compared with that of deionized water; and the thermal conductivity of kerosene-based magnetic fluid with concentration of 10% is increased 128.8% higher than that of kerosene based-liquid. An experimental platform for the cooling loop is set up to verify the starting time and heat transfer characteristics of the developed magnetic fluid.

Influence of Magnetic Particles and Magnetic Field on Gloss in UV Coating

UV-curable coatings possess numerous advantages, including high production rate, low environmental impact, and customizability, making them highly appealing for a wide range of applications. However, one of the greatest challenges in UV-curable coating is achieving an optimal low-gloss surface by adding matting agents to the coating formulation. Therefore, it is essential to find a suitable matting agent type and an efficient roughness creation method to tailor the surface gloss and generate a controlled low-gloss surface. In this study, modified magnetic particles were added to the coating formulation as matting agents, and the UV curing process was conducted under a magnetic field of 10 to 100 mT. The combined effect of adding magnetic particles and magnetic field during UV curing on the coatings’ surface gloss was investigated. The impact of modification, dispersion, and concentration of magnetic particles and the effect of magnetic field force on the final surface gloss and roughness were assessed. Moreover, the effect of the dispersion and concentration of magnetic particles on the photopolymerization of the coating was evaluated. The result indicated that both the magnetic field force and modification of the magnetic particles impact the surface roughness. A CI-APTES 5% wt. sample cured under a 60 mT magnetic field led to the highest decrease in 20° gloss.