Magnetochemistry, Volume 8, Issue 3 (March 2022) – 9 articles

Fuel injection nozzles are a key component of electronic injection engines, and their inner surface roughness affects the performance of the nozzles and restricts the working efficiency of the engine. Therefore, the polishing technology for a nozzle’s inner surface is particularly important. At present, abrasive flow polishing technology is commonly used to treat the inner surfaces of the nozzles. This study investigated the magnetic particles in the abrasive flow working medium. Due to the external magnetic field, magnetic particles are affected by the magnetic field force and change the polishing performance of the abrasive flow working medium. Through a numerical analysis and contrast experimental research, we can see that the choice of different grinding grain sizes, kinematic viscosity, magnetic field intensity, and process parameters, such as inlet pressure, with magnetic particles in a solid–liquid two-phase abrasive flow for polishing, can effectively improve the quality of the injection nozzle’s inner surface. The study also reveals that the influence of the nozzle’s inner surface polishing quality is significant and creates a mechanism for process parameters. Full article

The safety of the cells used for Advanced Therapy Medicinal Products is crucial for patients. Reliable methods for the cell purification are very important for the commercialization of those new therapies. With the large production scale envisioned for commercialization, the cell isolation methods need to be efficient, robust, operationally simple and generic while ensuring cell biological functionality and safety. In this study, we used high magnetized magnetic agarose-based beads conjugated with protein A to develop a new method for cell separation. A high separation efficiency of 91% yield and consistent isolation performances were demonstrated using population mixtures of human mesenchymal stem cells and HER2⁺ SKBR3 cells (80:20, 70:30 and 30:70). Additionally, high robustness against mechanical stress and minimal unspecific binding obtained with the protein A base conjugated magnetic beads were significant advantages in comparison with the same magnetic microparticles where the antibodies were covalently conjugated. This study provided insights on features of large high magnetized microparticles, which is promising for the large-scale application of cell purification. Full article

Superconducting niobium nitride (NbN) films with nominal thicknesses of 4 nm, 5 nm, 7 nm, and 9 nm were grown on sapphire substrates using atomic layer deposition (ALD). We observed probed Hall resistance (HR) ($R_{xy}$) in external out-of-plane magnetic fields up to 6 T and magnetoresistance (MR) ($R_{xx}$) in external in-plane and out-of-plane magnetic fields up to 6 T on NbN thin films in Van der Pauw geometry. We also observed that positive MR dominated. Our study focused on the analysis of interaction and localisation effects on electronic disorder in NbN in the normal state in temperatures that ranged from 50 K down to the superconducting transition temperature. By modelling the temperature and magnetic field dependence of the MR data, we extracted the temperature-dependent Coulomb interaction constants, spin–orbit scattering lengths, localisation lengths, and valley degeneracy factors. The MR model allowed us to distinguish between interaction effects (positive MR) and localisation effects (negative MR) for in-plane and out-of-plane magnetic fields. We showed that anisotropic dephasing scattering due to lattice non-idealities in NbN could be neglected in the ALD-grown NbN thin films. Full article

The objective of spectral analysis is to resolve and extract relevant features from experimental data in an optimal fashion. In continuous-wave (cw) electron spin resonance (ESR) spectroscopy, both g values of a paramagnetic center and hyperfine splitting (A) caused by its interaction with neighboring magnetic nuclei in a molecule provide important structural and electronic information. However, in the presence of g- and/or A-anisotropy and/or large number of resonance lines, spectral analysis becomes highly challenging. Either high-resolution experimental techniques are employed to resolve the spectra in those cases or a range of suitable ESR frequencies are used in combination with simulations to identify the corresponding g and A values. In this work, we present a wavelet transform technique in resolving both simulated and experimental cw-ESR spectra by separating the hyperfine and super-hyperfine components. We exploit the multiresolution property of wavelet transforms that allow the separation of distinct features of a spectrum based on simultaneous analysis of spectrum and its varying frequency. We retain the wavelet components that stored the hyperfine and/or super-hyperfine features, while eliminating the wavelet components representing the remaining spectrum. We tested the method on simulated cases of metal–ligand adducts at L-, S-, and X-band frequencies, and showed that extracted g values, hyperfine and super-hyperfine coupling constants from simulated spectra, were in excellent agreement with the values of those parameters used in the simulations. For the experimental case of a copper(II) complex with distorted octahedral geometry, the method was able to extract g and hyperfine coupling constant values, and revealed features that were buried in the overlapped spectra. Full article

Tunable and ultrasensitive surface plasmon resonance (SPR) sensors are highly desirable for monitoring stress hormones such as cortisol, a steroid hormone formed in the human body’s adrenal glands. This paper describes the detection of cortisol using a bimetallic SPR sensor based on a highly anisotropic two-dimensional material, i.e., phosphorene. Thicknesses of bi-metal layers, such as copper (Cu) and nickel (Ni), are optimized to achieve strong SPR excitation. The proposed sensor is rotated in-plane with a rotation angle (φ) around the z-axis to obtain the phosphorene anisotropic behavior. The performance parameters of the sensor are demonstrated in terms of higher sensitivity (347.78 °/RIU), maximum angular figure of merit (FOM* = 1780.3), and finer limit of detection (0.026 ng/mL). Furthermore, a significant penetration depth (203 nm) is achieved for the proposed sensor. The obtained results of the above parameters indicate that the proposed sensor outperforms the previously reported papers in the literature on cortisol detection using the SPR technique. Full article

For an inductive power transfer system, high transfer quality factor means that the system can obtain large theoretical transmission efficiency. In this paper, a method of coil optimization in a limited space to improve the transfer quality factor for a series-series compensated inductive power transfer system is presented. High transfer quality factor in a limited space can be achieved by determining the optimal number of turns with equal turn spacing coil, and then optimizing the distance between adjacent turn. The results of finite element simulation and experimental measurement show that the method proposed in this paper can obtain a higher transfer quality factor than the conventional method of winding coil with equal turn spacing. The method proposed in this paper can be used to guide the optimal design of coils in a limited space. Full article

Magnetic nanomaterials and nanostructures compose an innovative subject in sample preparation. Most of them are designed according to the properties of the target analytes on each occasion. The unique characteristics of nanomaterials enhance the proficiency at extracting and enriching due to their selective adsorption ability as well as easy separation and surface modification. Their remarkable properties, such as superparamagnetism, biocompatibility and selectivity have established magnetic materials as very reliable options in sample preparation approaches. In order to comprehend the range of utilization at magnetic materials and nanostructures, this review aims to present the most notable examples in sample preparation prior to liquid chromatography (LC) to the community of analytical chemists. Primarily, the review describes the principles of the techniques in which the magnetic materials are utilized and leaned on. Additionally, there is a diligent report about the novel magnetic techniques and finally a comparison to demonstrate the total point of view. Full article

Fabrication of high quality ferrimagnetic insulators is an essential step for ultrafast magnonics, which utilizes antiferromagnetic exchange of the ferrimagnetic materials. In this work, we deposit high-quality GdIG thin films on a (111)-oriented GGG substrate using the Metal Organic Decomposition (MOD) method, a simple and high throughput method for depositing thin film materials. We postannealed samples at various temperatures and examined the effect on structural properties such as crystallinity and surface morphology. We found a transition in the growth mode that radically changes the morphology of the film as a function of annealing temperature and obtained an optimal annealing temperature for a uniform thin film with high crystallinity. Optimized GdIG has a high potential for spin wave applications with a low damping parameter in the order of 10⁻³, which persists down to cryogenic temperatures. Full article

The study of biomagnetic fluid flow and heat transfer containing magnetic particles through an unsteady stretching/shrinking cylinder was numerically investigated in this manuscript. Biomagnetic fluid namely blood taken as base fluid and CoFe₂O₄ as magnetic particles. Where blood acts as an electrically conducting fluid along with magnetization/polarization. The main concentration is to study a time-dependent biomagnetic fluid flow with magnetic particles that passed through a two dimensional stretching/shrinking cylinder under the influence of thermal radiation, heat source and partial slip condition which has not been studied yet as far as best knowledge of authors. This model is consistent with the principles of magnetohydrodynamic and ferrohydrodynamic. The flow equations, such as momentum, energy which is described physically by a system of coupled, nonlinear partial differential equation with appropriate boundary conditions and converted into a nonlinear system of ordinary differential equations by using suitable similarity transformations. The resultant ODEs numerically solved by applying by applying an efficient numerical technique based on a common finite differencing method along with central differencing, tridiagonal matrix manipulation and an iterative procedure. The values assigned to the parameters are compatible with human body conditions. The numerous results concerning velocity, temperature and pressure field, as well as the skin friction and the rate of heat transfer, are presented for the parameters exhibiting physical significance, such as ferromagnetic interaction parameter, magnetic field parameter, volume fraction, unsteady parameter, curvature parameter, etc. The main numerical findings are that the fluid velocity is decreased as the ferromagnetic number is enhanced gradually in both stretching or shrinking cases whereas, the opposite behavior is found for the skin friction coefficient. The rate of heat transfer with ferromagnetic interaction parameter was also monitored and found that opposite behavior occurs for stretching and shrinking cases. Comparisons were made to check the accuracy of the present numerical results with published literature and found to be in excellent agreement. Hopefully, this proposed model will control the blood flow rate, as well as the rate of heat transfer, such as magnetic hyperthermia. Full article