Journal Description
Magnetochemistry
Magnetochemistry
is an international, peer-reviewed, open access journal on all areas of magnetism and magnetic materials published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Chemistry, Inorganic & Nuclear) / CiteScore - Q2 (Chemistry (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 15.8 days after submission; acceptance to publication is undertaken in 3.5 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.7 (2022);
5-Year Impact Factor:
2.5 (2022)
Latest Articles
Doping Effects on the Multiferroic Properties of KNbO3 Nanoparticles
Magnetochemistry 2024, 10(3), 19; https://doi.org/10.3390/magnetochemistry10030019 - 07 Mar 2024
Abstract
The magnetization, polarization, and band-gap energy in pure and ion-doped (KNO) bulk and nanoparticles (NPs) are investigated theoretically using a microscopic model and Green’s function theory. It is shown that KNO NPs are multiferroic. The size dependence of M and P
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The magnetization, polarization, and band-gap energy in pure and ion-doped (KNO) bulk and nanoparticles (NPs) are investigated theoretically using a microscopic model and Green’s function theory. It is shown that KNO NPs are multiferroic. The size dependence of M and P is studied. The magnetization M increases with decreasing NP size, whereas the polarization P decreases slightly. The properties of KNO can be tuned by ion doping, for example, through the substitution of transition metal ions at the Nb site or Na ions at the K site. By ion doping, depending on the relation between the doping and host ion radii, different strains appear. They lead to changes in the exchange interaction constants, which are inversely proportional to the lattice parameters. So, we studied the macroscopic properties on a microscopic level. By doping with transition metal ions (Co, Mn, Cr) at the Nb site, M increases, whereas P decreases. Doped KNO NPs exhibit the same behavior as doped bulk KNO, but the values of the magnetization and polarization in KNO NPs are somewhat enhanced or reduced due to the size effects compared to the doped bulk KNO. In order to increase P, we substituted the K ions with Na ions. The polarization increases with increasing magnetic field, which is evidence of the multiferroic behavior of doped KNO bulk and NPs. The behavior of the band-gap energy also depends on the dopants. decreases with increasing Co, Mn, and Cr ion doping, whereas it increases with Zn doping. The results are compared with existing experimental data, showing good qualitative agreement.
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(This article belongs to the Special Issue Magnetic Materials, Thin Films and Nanostructures (Volume II))
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The Influence of Current Magnitudes and Profiles on the Sedimentation of Magnetorheological Fluids: An Experimental Work
by
Elliza Tri Maharani, Myeong-Won Seo, Jung Woo Sohn, Jong-Seok Oh and Seung-Bok Choi
Magnetochemistry 2024, 10(3), 18; https://doi.org/10.3390/magnetochemistry10030018 - 07 Mar 2024
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Magnetorheological fluids (MRFs) are widely used for various kinds of controllable devices since their properties can be controlled by an external magnetic field. Despite many benefits of MRFs, such as fast response time, the sedimentation arisen due to the density mismatch of the
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Magnetorheological fluids (MRFs) are widely used for various kinds of controllable devices since their properties can be controlled by an external magnetic field. Despite many benefits of MRFs, such as fast response time, the sedimentation arisen due to the density mismatch of the compositions between iron particles and carrier oil is still one of bottlenecks to be resolved. Many studies on the sedimentation problem of MR fluids have been carried out considering appropriate additives, nanoparticles, and several carrier oils with different densities. However, a study on the effect of current magnitudes and profiles on the sedimentation is considerably rare. Therefore, this study experimentally investigates sedimentation behaviors due to different current magnitudes and different magnitude profiles such as square and sine waves in different diameters. The evaluation was performed by visual observation to obtain the sedimentation rate. It was found that the average sedimentation rate of the square type of current is slower compared to the sinusoidal type. It has also been identified that the higher intensity of the applied current results in a stronger electromagnetic field, which could slow down the sedimentation. The results achieved in this work can be effectively used to reduce particle sedimentation in the controller design of various application systems utilizing MRFs in which the controller generates a different magnitude and different profile of the external magnetic field.
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Advances in Engine Efficiency: Nanomaterials, Surface Engineering, and Quantum-Based Propulsion
by
Mario J. Pinheiro
Magnetochemistry 2024, 10(3), 17; https://doi.org/10.3390/magnetochemistry10030017 - 27 Feb 2024
Abstract
This study explores ground-breaking methods for improving engine efficiency by combining cutting-edge materials, theoretical frameworks, and alternative energy paradigms. The paper primarily offers a cohesive framework, built from our variational method which combines thermal and entropic engines. We investigate the fabrication of hydrophobic
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This study explores ground-breaking methods for improving engine efficiency by combining cutting-edge materials, theoretical frameworks, and alternative energy paradigms. The paper primarily offers a cohesive framework, built from our variational method which combines thermal and entropic engines. We investigate the fabrication of hydrophobic and other functionally specific surfaces using nanomaterials and sophisticated surface engineering techniques that efficiently utilize entropy gradient forces. Additionally, this publication explores the fields of quantum-based propulsion systems and information-burning engines, creating a connecting link between theoretical foundations and real-world technical implementations. The study emphasizes the multifaceted character of engine research and its crucial role in shaping a future in which sustainability and efficiency are intimately connected.
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(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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Syntheses, Structures, and Properties of Mono- and Dinuclear Acetylacetonato Ruthenium(III) Complexes with Chlorido or Thiocyanato Ligands
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Kai Nakashima, Chihiro Hayami, Shino Nakashima, Haruo Akashi, Masahiro Mikuriya and Makoto Handa
Magnetochemistry 2024, 10(3), 16; https://doi.org/10.3390/magnetochemistry10030016 - 27 Feb 2024
Abstract
The mononuclear and dinuclear ruthenium(III) complexes trans-Ph4P[RuIII(acac)2Cl2] (1), Ph4P[{RuIII(acac)Cl}2(μ-Cl)3] (2) and trans-Ph4P[RuIII(acac)2(NCS)2
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The mononuclear and dinuclear ruthenium(III) complexes trans-Ph4P[RuIII(acac)2Cl2] (1), Ph4P[{RuIII(acac)Cl}2(μ-Cl)3] (2) and trans-Ph4P[RuIII(acac)2(NCS)2]·0.5C6H14 (3·0.5C6H14) were synthesized. Single crystals of 1, 2·H2O and 3·CH3CN suitable for X-ray crystal structure analyses were obtained through recrystallization from DMF for 1 and 2·H2O and from acetonitrile for 3·CH3CN. An octahedral Ru with bis-chelate-acac ligands and axial chlorido or κ-N-thiocyanido ligands (for 1 and 3·CH3CN) and triply µ-chlorido-bridged dinuclear Ru2 for 2·H2O were confirmed through the structure analyses. The Ru–Ru distance of 2.6661(2) of 2·H2O is indicative of the existence of the direct metal–metal interaction. The room temperature magnetic moments (μeff) are 2.00 and 1.93 μB for 1 and 3·0.5C6H14, respectively, and 0.66 μB for 2. The temperature-dependent (2–300 K) magnetic susceptibility showed that the strong antiferromagnetic interaction (J ≤ −800 cm−1) is operative between the ruthenium(III) ions within the dinuclear core. In the 1H NMR spectra measured in CDCl3 at 298 K, the dinuclear complex 2 showed signals for the acac ligand protons at 2.50 and 2.39 ppm (for CH3) and 5.93 ppm (for CH), respectively, while 1 and 3·0.5C6H14 showed signals with large paramagnetic shifts; −17.59 ppm (for CH3) and −57.01 ppm (for CH) for 1 and −16.89 and −17.36 ppm (for CH3) and −53.67 and −55.53 ppm (for CH) for 3·0.5C6H14. Cyclic voltammograms in CH2Cl2 with an electrolyte of nBu4N(ClO4) showed the RuIII → RuIV redox wave at 0.23 V (vs. Fc/Fc+) for 1 and the RuIII → RuII waves at −1.39 V for 1 and −1.25 V for 3·0.5C6H14 and the RuIII–RuIII → RuIII–RuIV and RuIII–RuIII → RuIII–RuIV waves at 0.91 V and −0.79 V for 2.
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(This article belongs to the Section Molecular Magnetism)
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Open AccessArticle
High-Strength Copper/Silver Alloys Processed by Cold Spraying for DC and Pulsed High Magnetic Fields
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Simon Tardieu, Hanane Idrir, Christophe Verdy, Olivier Jay, Nelson Ferreira, François Debray, Anne Joulain, Christophe Tromas, Ludovic Thilly and Florence Lecouturier-Dupouy
Magnetochemistry 2024, 10(3), 15; https://doi.org/10.3390/magnetochemistry10030015 - 21 Feb 2024
Abstract
High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at
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High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features.
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(This article belongs to the Special Issue Feature Papers in Materials for High Field Resistive Magnets)
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Nano-Magnonic Crystals by Periodic Modulation of Magnetic Parameters
by
Alison Roxburgh and Ezio Iacocca
Magnetochemistry 2024, 10(3), 14; https://doi.org/10.3390/magnetochemistry10030014 - 21 Feb 2024
Abstract
Magnonic crystals are metamaterials whose magnon behavior can be controlled for specific applications. To date, most magnonic crystals have relied on nanopatterning and magnetostatic waves. Here, we analytically and numerically investigate magnonic crystals defined by modulating magnetic parameters at the nanoscale, which predominantly
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Magnonic crystals are metamaterials whose magnon behavior can be controlled for specific applications. To date, most magnonic crystals have relied on nanopatterning and magnetostatic waves. Here, we analytically and numerically investigate magnonic crystals defined by modulating magnetic parameters at the nanoscale, which predominantly act on exchange-dominated, sub-100 nm magnons. We focus on two cases: the variation in the exchange constant, and the DMI constant. We found that the exchange constant modulation gives rise to modest band gaps in the forward volume wave and surface wave configurations. The modulation of the DMI constant was found to have little effect on the magnonic band structure, leading instead to a behavior expected for unpatterned thin films. We believe that our results will be interesting for future experimental investigations of nano-designed magnonic crystals and magnonic devices, where material parameters can be locally controlled, e.g., by thermal nano-lithography.
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(This article belongs to the Special Issue Spin Waves in Magnonic Crystals and Hybrid Ferromagnetic Structures)
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Compatibility of LaFe13−x−yMnxSiyH1.6 and Eutectic Liquid GaInSn Alloy
by
Jamieson Brechtl, Joseph Rendall, Mingkan Zhang, Michael R. Koehler, Kashif Nawaz and Ayyoub M. Momen
Magnetochemistry 2024, 10(2), 13; https://doi.org/10.3390/magnetochemistry10020013 - 12 Feb 2024
Abstract
The heat transfer rate of magnetocaloric regenerators is a topic of extensive research and the cyclability of these regenerators is critical to the operation of systems with a high coefficient of performance (e.g., potentially >22, significantly higher than typical vapor compression cooling technologies).
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The heat transfer rate of magnetocaloric regenerators is a topic of extensive research and the cyclability of these regenerators is critical to the operation of systems with a high coefficient of performance (e.g., potentially >22, significantly higher than typical vapor compression cooling technologies). To enable a high operating frequency that will result in a high specific cooling power, the heat transfer fluid should have high thermal conductivity and lower specific heat, i.e., higher thermal diffusivity. Eutectic metal alloys possess these qualities, such as gallium–indium–tin (Galinstan), whose thermal diffusivity has been found to be approximately an order of magnitude higher than water. For this study, the effects of eutectic liquid Galinstan exposure on the phase stability of LaFe13−x−yMnxSiyH1.6 magnetocaloric powders in an active magnetic regenerator device were investigated. The powders were characterized before and after exposure to Galinstan using X-ray diffraction, in which the phases were determined using the Rietveld refinement technique and X-ray fluorescence. It was found that after Galinstan exposure, hydrogen containing phases were present in the powder, suggesting that the hydrogen was lost from the magnetocaloric phase. The magnetocaloric phase degradation indicates that the powder was incompatible with the Galinstan metal in an environment with moisture.
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(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)
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Experimental Thermal Conductivity Studies of Agar-Based Aqueous Suspensions with Lignin Magnetic Nanocomposites
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Bishal Gautam, Saja M. Nabat Al-Ajrash, Mohammad Jahid Hasan, Abhishek Saini, Sarah J. Watzman, Esteban Ureña-Benavides and Erick S. Vasquez-Guardado
Magnetochemistry 2024, 10(2), 12; https://doi.org/10.3390/magnetochemistry10020012 - 10 Feb 2024
Abstract
Nanoparticle additives increase the thermal conductivity of conventional heat transfer fluids at low concentrations, which leads to improved heat transfer fluids and processes. This study investigates lignin-coated magnetic nanocomposites (lignin@Fe3O4) as a novel bio-based magnetic nanoparticle additive to enhance
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Nanoparticle additives increase the thermal conductivity of conventional heat transfer fluids at low concentrations, which leads to improved heat transfer fluids and processes. This study investigates lignin-coated magnetic nanocomposites (lignin@Fe3O4) as a novel bio-based magnetic nanoparticle additive to enhance the thermal conductivity of aqueous-based fluids. Kraft lignin was used to encapsulate the Fe3O4 nanoparticles to prevent agglomeration and oxidation of the magnetic nanoparticles. Lignin@Fe3O4 nanoparticles were prepared using a pH-driven co-precipitation method with a 3:1 lignin to magnetite ratio and characterized by X-ray diffraction, FT-IR, thermogravimetric analysis, and transmission electron microscopy. The magnetic properties were characterized using a vibrating sample magnetometer. Once fully characterized, lignin@Fe3O4 nanoparticles were dispersed in aqueous 0.1% w/v agar–water solutions at five different concentrations, from 0.001% w/v to 0.005% w/v. Thermal conductivity measurements were performed using the transient line heat source method at various temperatures. A maximum enhancement of 10% in thermal conductivity was achieved after adding 0.005% w/v lignin@Fe3O4 to the agar-based aqueous suspension at 45 °C. At room temperature (25 °C), the thermal conductivity of lignin@Fe3O4 and uncoated Fe3O4 agar-based suspensions was characterized at varying magnetic fields from 0 to 0.04 T, which were generated using a permanent magnet. For this analysis, the thermal conductivity of lignin magnetic nanosuspensions initially increased, showing a 5% maximum peak increase after applying a 0.02 T magnetic field, followed by a decreasing thermal conductivity at higher magnetic fields up to 0.04 T. This result is attributed to induced magnetic nanoparticle aggregation under external applied magnetic fields. Overall, this work demonstrates that lignin-coated Fe3O4 nanosuspension at low concentrations slightly increases the thermal conductivity of agar aqueous-based solutions, using a simple permanent magnet at room temperature or by adjusting temperature without any externally applied magnetic field.
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(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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Optimal Selection for Redox Couples and Enhanced Performance through Magnetic Nanofluid Electrolyte in Solar Flow Batteries
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Zixing Gu, Ping Lu, Zihan Zhang, Qiang Ma, Huaneng Su and Qian Xu
Magnetochemistry 2024, 10(2), 11; https://doi.org/10.3390/magnetochemistry10020011 - 06 Feb 2024
Cited by 1
Abstract
The limited photoelectric conversion efficiency poses one of the critical constraints on commercializing solar flow batteries (SFBs). This study compares the chemical and photoelectrochemical properties of three commonly used redox couples. Additionally, magnetic Fe3O4 nanoparticles, for the first time, are
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The limited photoelectric conversion efficiency poses one of the critical constraints on commercializing solar flow batteries (SFBs). This study compares the chemical and photoelectrochemical properties of three commonly used redox couples. Additionally, magnetic Fe3O4 nanoparticles, for the first time, are introduced to optimize the electrolyte, and they are compared with the original electrolyte. Across different redox couples, the variations in semiconductor flat-band potentials and carrier concentrations result in changes in photoelectric current density. Notably, FeCl2/FeCl3 redox coupled with TiO2 photoelectrodes exhibits the highest photoelectric current density, reaching 75.7 µA cm−2. However, the trade-off of this electrolyte, i.e., providing high photocurrent while being unable to supply sufficient open-circuit voltage, imposes limitations on the practical application of SFBs. Alternatively, for TEMPO and 4-OH-TEMPO electrolytes, which can provide a higher open-circuit voltage, the electrochemical activity is enhanced, and the solution ohmic resistance is reduced by introducing magnetic nanoparticles to form a magnetic nanofluid. As a result, the photoanode’s photocurrent density increases by 36.6% and 17.0%, respectively, in the two electrolytes. The work reported here effectively addresses the current issue of low photocurrent density in SFBs and presents new optimization strategies for SFBs.
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(This article belongs to the Special Issue Feature Paper on Magnetic Nanospecies—Educational Aspects)
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On the Magnetization and Entanglement Plateaus in One-Dimensional Confined Molecular Magnets
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Javier I. Norambuena Leiva, Emilio A. Cortés Estay, Eric Suarez Morell and Juan M. Florez
Magnetochemistry 2024, 10(2), 10; https://doi.org/10.3390/magnetochemistry10020010 - 01 Feb 2024
Abstract
One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on
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One-dimensional (1D) magnetic systems offer rich phenomena in the quantum limit, proving more chemically accessible than zero-dimensional or higher-dimensional frameworks. Single-walled carbon nanotubes (SWCNT) have recently been used to encapsulate trimetric nickel(II) acetylacetonate [Nanoscale, 2019, 11, 10615–10621]. Here, we investigate the magnetization on spin chains based on nickel trimers by Matrix Product State (MPS) simulations. Our findings reveal plateaus in the exchange/magnetic-field phase diagram for three coupling configurations, showcasing effective dimeric and trimeric spin-ordering with similar or staggered entanglement across chains. These ordered states allow the qubit-like tuning of specific local magnetic moments, exhibiting disengagement or uniform coupling in entanglement plateaus. This behavior is consistent with the experimental transition from frustrated (3D) to non-frustrated (1D) molecules, corresponding to large and smaller SWCNT diameters. Our study offers insights into the potential of 1D-confined trimers for quantum computation, extending beyond the confinement of trimetric nickel-based molecules in one dimension.
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(This article belongs to the Special Issue Advances in Functional Materials with Tunable Magnetic Properties)
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Low-Frequency Dynamic Magnetic Fields Decrease Cellular Uptake of Magnetic Nanoparticles
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Anna V. Ivanova, Nelly S. Chmelyuk, Aleksey A. Nikitin, Alexander G. Majouga, Vladimir P. Chekhonin and Maxim A. Abakumov
Magnetochemistry 2024, 10(2), 9; https://doi.org/10.3390/magnetochemistry10020009 - 01 Feb 2024
Abstract
Magnetic nanoparticles have gained attention as a potential structure for therapy and diagnosing oncological diseases. The key property of the magnetic nanoparticles is the ability to respond to an external magnetic field. It is known that magnetofection causes an increase in the cellular
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Magnetic nanoparticles have gained attention as a potential structure for therapy and diagnosing oncological diseases. The key property of the magnetic nanoparticles is the ability to respond to an external magnetic field. It is known that magnetofection causes an increase in the cellular uptake of RNA and DNA in complexes with magnetic nanoparticles in the presence of a permanent magnetic field. However, the influence of a dynamic magnetic field on the internalization of MNPs is not clear. In this work, we propose the idea that applying external low-frequency dynamic magnetic fields may decrease the cellular uptake, such as macrophages and malignant neuroblastoma. Using fluorescence microscopy and atomic emission spectroscopy, we found that oscillating magnetic fields decreased the cellular uptake of magnetic nanoparticles compared to untreated cells by up to 46%. In SH-SY5Y tumor cells and macrophage RAW264.7 cells, the absolute values of Fe per cell differed by 0.10 pg/cell and 0.33 pg/cell between treated and untreated cells, respectively. These results can be applied in the control of the cellular uptake in different areas of biomedicine.
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(This article belongs to the Special Issue Advanced Magnetic Nanomaterial for Cancer Therapy and Diagnosis)
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Magnetic and Magnetoelectric Materials
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Devashibhai Adroja and Dmitry Filippov
Magnetochemistry 2024, 10(2), 8; https://doi.org/10.3390/magnetochemistry10020008 - 01 Feb 2024
Abstract
Magnetic materials are an important class of materials for the development of technology as well as for our fundamental understanding of microscopic magnetic interactions [...]
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(This article belongs to the Special Issue Editorial Board Members’ Collection Series: Magnetic and Magnetoelectric Materials)
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Experimental Investigations on the Ferromagnetic Resonance and Absorbing Properties of a Ferrofluid in the Microwave Range
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Iosif Malaescu, Catalin N. Marin and Paul C. Fannin
Magnetochemistry 2024, 10(2), 7; https://doi.org/10.3390/magnetochemistry10020007 - 26 Jan 2024
Abstract
Measurements of complex magnetic permeability, μ(f,H) = μ′(f,H) − iμ″(f,H) and dielectric permittivity ε(f,H) = ε′(f,H) − iε
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Measurements of complex magnetic permeability, μ(f,H) = μ′(f,H) − iμ″(f,H) and dielectric permittivity ε(f,H) = ε′(f,H) − iε″(f,H), in the frequency range, f of (0.4–7) GHz, and polarizing field, H of (0–135) kA/m, were performed, for a kerosene-based ferrofluid with magnetite nanoparticles. Based on these measurements, the phenomenon of ferromagnetic resonance was highlighted and some microwave propagation parameters of the ferrofluid were determined: the attenuation constant, α(f,H), and the reflection coefficient, R(f,H), at the air-material interface, at the normal incidence. Knowing these parameters we proposed a theoretical model establishing for the first time an equation that allows the calculation of the overall reflection coefficient, Rw(f,H), at the normal incidence of the wave, for a ferrofluid of thickness d, deposited on a totally reflective support, following multiple internal reflections of the electromagnetic wave in the material. The results show that by increasing both, H, and d, the parameter, Rw(f,H) presents a minimum that decreases from 0.90 (for d = 2 mm) to 0.64 (for d = 10 mm), at frequency f = 5 GHz, which indicates an increase in the absorption of the electromagnetic wave by the ferrofluid. The obtained results are useful in the study of some materials that could be used as electromagnetic absorbers in the microwave range, by the determination of the overall reflection coefficient, Rw(f,H), controlled both by the thickness, d, of the absorber and by the external applied field, H.
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(This article belongs to the Special Issue Functional Magnetic Nanomaterials and Nanostructures: Properties and Applications)
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A Magnet Splicing Method for Constructing a Three-Dimensional Self-Decoupled Magnetic Tactile Sensor
by
Huangzhe Dai, Zheyan Wu, Chenxian Meng, Chengqian Zhang and Peng Zhao
Magnetochemistry 2024, 10(1), 6; https://doi.org/10.3390/magnetochemistry10010006 - 21 Jan 2024
Abstract
Tactile sensory organs for three-dimensional (3D) force perception are essential for most living organisms and enable them to perform complex and sophisticated tasks to survive and evolve. Magnetic-based tactile sensors have been developed rapidly in recent years due to the exploitability of 3D
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Tactile sensory organs for three-dimensional (3D) force perception are essential for most living organisms and enable them to perform complex and sophisticated tasks to survive and evolve. Magnetic-based tactile sensors have been developed rapidly in recent years due to the exploitability of 3D force decoupling. Here, a method of magnet splicing is introduced, which can be applied to a magnetic tactile sensor to realize 3D self-decoupling of magnets’ displacements. This method enables the magnets to produce a completely consistent magnetic field distribution as the ideal magnetization model within a certain working range, eliminating the compensation and correction of the 3D magnetic flux density signal. This method carves out a new way for the practical application of 3D decoupling theory, showcasing the great potential in the fields of magnetic sensors and magnetic actuators.
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(This article belongs to the Special Issue Functional Magnetic Materials: From Design to Application)
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Preparation and Optimization of the Adsorbent for Phosphorus Removal Using the Response Surface Method
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Zhanmei Zhang, Zuqin Zou, Xiaoyu Ren, Yunxuan Huang, Yang Deng and Huaili Zheng
Magnetochemistry 2024, 10(1), 5; https://doi.org/10.3390/magnetochemistry10010005 - 09 Jan 2024
Cited by 1
Abstract
A diatomaceous earth (DE)-based adsorbent DE-Ce was prepared and optimized to remove phosphorus from wastewater. DE was modified through purification–cerium loading, improving its phosphorus adsorption capacity and recycling ability. The preparation conditions were optimized using the Box–Behnken design, and the response surface method
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A diatomaceous earth (DE)-based adsorbent DE-Ce was prepared and optimized to remove phosphorus from wastewater. DE was modified through purification–cerium loading, improving its phosphorus adsorption capacity and recycling ability. The preparation conditions were optimized using the Box–Behnken design, and the response surface method was employed to analyze the effects of roasting temperature, cerium concentration, and HCl concentration on the preparation of DE-Ce. Scanning electron microscopy, X-ray fluorescence spectrometry, and X-ray photoelectron spectroscopy were used for characterization, with results indicating that HCl washing can effectively remove impurities. Cerium was mainly loaded onto DE in the form of Ce(OH)3, and pore size and capacity increased following cerium loading, with the formation of a macroporous structure. The obtained DE-Ce adsorbent removed 98.30% phosphorous, with the removal process following the secondary kinetic and Langmuir models. According to material characterization and model analysis results, the phosphorus removal mechanism primarily involves electrostatic adsorption, ligand exchange, and precipitation. Overall, the findings indicate that cerium modification can effectively improve the adsorption capacity of DE.
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(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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The Effect of Magnetically Induced Local Structure and Volume Fraction on the Electromagnetic Properties of Elastomer Samples with Ferrofluid Droplet Inserts
by
Catalin N. Marin and Iosif Malaescu
Magnetochemistry 2024, 10(1), 4; https://doi.org/10.3390/magnetochemistry10010004 - 02 Jan 2024
Abstract
The magnetic permeability (μ), dielectric permittivity (ε) and electrical conductivity (σ) of six elastomer samples obtained by mixing silicone rubber (RTV-530) with a kerosene-based ferrofluid in different volume fractions (φ), 1.31%, 2.59% and 3.84%, were
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The magnetic permeability (μ), dielectric permittivity (ε) and electrical conductivity (σ) of six elastomer samples obtained by mixing silicone rubber (RTV-530) with a kerosene-based ferrofluid in different volume fractions (φ), 1.31%, 2.59% and 3.84%, were determined using complex impedance measurements over a frequency range of 500 Hz–2 MHz. Three samples (A0, B0 and C0) were manufactured in the absence of a magnetic field, and the other three samples (Ah, Bh and Ch) were manufactured in the presence of a magnetic field, H = 43 kA/m. The component μ″ of the complex effective magnetic permeability of all samples presents a maximum at a frequency, fmax, that moves to higher values by increasing φ, with this maximum being attributed to Brownian relaxation processes. The conductivity spectrum, σ (f), of all samples follows the Jonscher universal law, which allows for both the determination of the static conductivity, σDC, and the barrier energy of the electrical conduction process, Wm. For the same φ, Wm is lower, and σDC is higher in the samples Ah, Bh and Ch than in the samples A0, B0 and C0. The performed study is useful in manufacturing elastomers with predetermined properties and for possible applications such as magneto-dielectric flexible electronic devices, which can be controlled by the volume fraction of particles or by an external magnetic field.
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(This article belongs to the Special Issue Composites for Electromagnetic and Magnetoelectric Applications in Electronics)
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Open AccessCorrection
Correction: Li et al. Dry Friction Performances of MoNx Coatings Deposited by High–Power Pulsed Magnetron Sputtering. Magnetochemistry 2023, 9, 60
by
Fuqiang Li, Wei Dai, Qimin Wang, Haiqing Li and Zhengtao Wu
Magnetochemistry 2024, 10(1), 3; https://doi.org/10.3390/magnetochemistry10010003 - 29 Dec 2023
Abstract
In the original publication [...]
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(This article belongs to the Section Magnetic Field)
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The Influence of Viscosity on Heat Dissipation under Conditions of the High-Frequency Oscillating Magnetic Field
by
Matus Molcan, Andrzej Skumiel, Jana Tothova, Katarina Paulovicova, Peter Kopcansky and Milan Timko
Magnetochemistry 2024, 10(1), 2; https://doi.org/10.3390/magnetochemistry10010002 - 24 Dec 2023
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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
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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.
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Open AccessEditorial
Functional Molecular Materials Insights
by
Laura C. J. Pereira and Dulce Belo
Magnetochemistry 2024, 10(1), 1; https://doi.org/10.3390/magnetochemistry10010001 - 20 Dec 2023
Abstract
In the commemorative Special Issue titled “Insights into Functional Molecular Materials—A Themed Collection Honoring Professor Manuel Almeida on His 70th Birthday”, eminent researchers from around the globe in the field of molecular materials science come together to acknowledge and celebrate the notable scientific
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In the commemorative Special Issue titled “Insights into Functional Molecular Materials—A Themed Collection Honoring Professor Manuel Almeida on His 70th Birthday”, eminent researchers from around the globe in the field of molecular materials science come together to acknowledge and celebrate the notable scientific contributions of Professor Almeida [...]
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(This article belongs to the Special Issue Functional Molecular Materials Insights—a Themed Issue in Honour of Professor Manuel Almeida on the Occasion of His 70th Birthday)
Open AccessEditor’s ChoiceArticle
Effect of Electrode–Normal Magnetic Field on the Motion of Hydrogen Bubbles
by
Yen-Ju Chen, Yan-Hom Li and Ching-Yao Chen
Magnetochemistry 2023, 9(12), 233; https://doi.org/10.3390/magnetochemistry9120233 - 18 Dec 2023
Abstract
In comparison to alternative methods for hydrogen production, water electrolysis stands out as the optimal means for obtaining ultra-pure hydrogen. However, its widespread adoption is significantly hampered by its low energy efficiency. It has been established that the introduction of an external magnetic
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In comparison to alternative methods for hydrogen production, water electrolysis stands out as the optimal means for obtaining ultra-pure hydrogen. However, its widespread adoption is significantly hampered by its low energy efficiency. It has been established that the introduction of an external magnetic field can mitigate energy consumption, consequently enhancing electrolysis efficiency. While much of the research has revealed that an electrode–parallel magnetic field plays a crucial role in enhancing the bubble detachment process, there has been limited exploration of the effect of electrode–normal magnetic fields. In this work, we compare the water electrolysis efficiency of a circular electrode subjected to electrode–normal magnetic field resulting in a magnet edge effect and electrode edge effect by varying the sizes of the magnet and electrode. The findings indicate that a rotational flow caused by the Lorentz force facilitates the detachment of the hydrogen from the electrode surface. However, the rotation direction of hydrogen gas bubbles generated by the magnet edge effect is opposite to that of electrode edge effect. Furthermore, the magnet edge effect has more significant influence on the hydrogen bubbles’ locomotion than the electrode edge effect. With an electrode gap of 30 mm, employing the magnet edge effect generated by a single magnet leads to an average of 4.9% increase in current density. On the other hand, the multiple magnet effects created by multiple small magnets under the electrode can further result in an average 6.6% increase in current density. Nevertheless, at an electrode spacing of 50 mm, neither the magnet edge effect nor the electrode edge effect demonstrates a notable enhancement in conductivity. In reality, the electrode edge effect even leads to a reduction in conductivity.
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(This article belongs to the Special Issue Advances in Electrochemical Properties of Magnetic Materials)
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