Magnetic Field Intensity Research Articles

Modeling magnetic field amplification in supernova remnants driven by laser

Abstract The origin of magnetic fields and their amplification have always been hot topics in fields such as astrophysics and high-energy-density physics. Among them, the turbulent dynamo effect is an important candidate mechanism, and the interaction between supernova remnants (SNRs) is an important carrier for studying the amplification effect of turbulent magnetic fields. In this paper, we use the radiation magnetohydrodynamic simulation program to carry out a scaling simulation study on the amplification effect of turbulent magnetic fields in the interaction of SNRs driven by powerful lasers. We investigate and compare the evolution of turbulence under different laser driving methods, different directions, and different intensities of initial external environmental magnetic fields. Here, we carefully identify the contributions of Biermann self-generated magnetic fields and environmental magnetic fields in the process of magnetic field amplification, present magnetic energy spectra, and magnetic field amplification factors, and analyze the influence of radiative cooling effect on turbulence and magnetic field evolution. The results show that the collision direction component of the environmental magnetic field dominates the process of magnetic field amplification, and the frequency spectrum of turbulence is consistent with Kolmogorov’s law. The research results are necessary for sorting out and elucidating the physical mechanism of magnetic field amplification in SNRs, and have reference significance for regulating turbulence in strong magnetic fields in the future.

Effect of physical field-assisted freezing on the quality attributes of frozen baked sweet potato and its optimization

Freezing plays a crucial role in ensuring the safety of foods over long storage periods. However, ice crystals within the cells can cause irreversible damages to tissue structures during the freezing process, resulting a significant problem on the quality. The present study aimed to investigate the effects of physical field-assisted freezing on the quality attributes of frozen baked sweet potato and identify the optimum operational parameters of quick-frozen process. Combination of magnetic field and ultrasound suggested the best results, with a 58.33% reduction in freezing time, 59.63% reduction in thawing loss, compared to IF. The hardness and the signal values of Sweetness and W2W of CF were 58.90%, 20.03%, and 27.07% higher than those of IF, which showed that CF have better maintenance of sample quality. Low field-nuclear magnetic resonance results showed that CF caused a decrease in the proportion of free water and an increase in the proportion of immobile water, and the water status are more similar to FB. Microscopic observations confirmed that the CF had the smallest and the most evenly distribution of ice crystals. Optimization of frozen baked sweet potato via response surface methodology, which revealed that the optimal conditions included a magnetic field intensity of 30 mT, an ultrasonic intensity of 320 W, and an ultrasonic time of 10 s. Therefore, treatment of combination with magnetic field and ultrasound is a promising novel method to improve the quality of frozen foods.

Durably Superhydrophobic Magnetic Cobalt Ferrites for Highly Efficient Oil-Water Separation and Fast Microplastic Removal.

Microplastic pollution has become a primary global concern in the 21st century. Recyclable magnetic particles with micro-nanostructures are considered an efficient and economical way to remove microplastics from water. In this study, superhydrophobic magnetic cobalt ferrite particles were prepared by using a simple coprecipitation method combined with surface functionalization. The micromorphology, chemical composition, hysteresis loop, and surface contact angle of the functionalized cobalt ferrite were characterized. The separation efficiency and absorption capacity of cobalt ferrite particles in water-oil separation and microplastic removal were investigated. The results showed that the saturation magnetic field intensity of cobalt ferrite was 65.52 emu/g, the residual magnetization intensity (Mr) was 18.79 emu/g, and the low coercivity was 799.83 Oe. Cobalt ferrites had stable superhydrophobicity in the pH range of 1-13. The separation efficiency of cobalt ferrite powder for four oil-water mixture separations was higher than 94.2%. The separation efficiency was as high as 99.6% in the separation of the hexane and water mixtures. Due to the synergistic effect of the hydrophobic effect and van der Waals force, the functionalized magnetic cobalt ferrite had a high and stable microplastic removal efficiency and capture capacity. The removal efficiency of microplastics was close to 100%, and the capture capacity was 2.56 g/g. After ten microplastic removal cycles, the removal efficiency reached more than 98%, and the surface contact angle was still greater than 150°.

Coupling nanoscopic tomography and micromagnetic modelling to assess the stability of geomagnetic recorders

The recording of planetary magnetic fields is often attributed to uniformly-magnetised nanoscopic iron oxides, called single-domain. Yet, the main magnetic constituents of rocks are more complex, non-uniformly magnetised grains in single or multi-vortex states. We know little about their behaviour due to limitations in defining their precise shape and internal magnetic structure. Here we combine non-destructive Ptychographic X-ray Computed Nano-tomography with micromagnetic modelling to explore the magnetic stability of remanence-bearing minerals. Applied to a microscopic rock sample, we identified hundreds of nanoscopic grains of magnetite/maghemite with diverse morphologies. Energy barrier calculations were performed for these irregularly shaped grains. For some grains, these morphological irregularities near the transition from single-domain to the single-vortex state allow for multiple domain states, some unstable and unable to record the field for significant periods. Additionally, some other grains exhibit temperature-dependent occupancy probabilities, potentially hampering experiments to recover the intensity of past magnetic fields.

Characterizing the Magnetic and Plasma Environment Upstream of Ganymede

AbstractWe present an application of the latest UCL‐AGA magnetodisc model (MDISC) to the study of the magnetic and plasma conditions in the near‐Ganymede space. By doing this, we provide a comparison with measurements from Juno's most recent flyby of the Jovian moon, perijove 34 (PJ34). We find good agreement between the model results and the magnetometer data, pointing toward a hot plasma index value (2.7190.024)107 Pa m T−1 and an effective magnetodisc radius (79.51.1) Jupiter radii for the Jovian magnetosphere, for the duration of the trajectory, suggesting a configuration with middling levels of expansion. We also predict the plasma conditions observed by Juno during the same flight‐path, as well as the typical conditions over the orbit of Ganymede, with the magnetic and hot plasma pressures assuming dominant roles. Finally, these results are compared with functional fits of a compilation of Galileo flyby data obtained in the vicinity of Ganymede's orbit, suggesting Juno experienced somewhat similar conditions, despite a systematic overestimation in magnetic field intensity in the near‐Ganymede space.

Improving surface integrity of GH4169 alloy through magnetic-assisted cutting

GH4169 alloy presents superior properties such as high strength and resistance to high temperature, but possesses poor machinability. To ameliorate the problem and improve the machined surface integrity of GH4169 alloy, this paper focused on the application of magnetic-assisted cutting (MAC) for GH4169 alloy. In the MAC process, a permanent magnetic field (the magnetic field intensity is 0.25 T) was applied to the workpiece material during cutting, and its impact on chip morphology, tool damage and surface integrity was investigated. By comparing to traditional cutting (TC), the introduction of a magnetic field results in a reduction in the chip thickness and minimizes chip serration, leading to smoother cutting process and reduced fluctuations in cutting forces. Meanwhile, the introduction of magnetic field resulted in a substantial decrease in the notch wear and abrasion of cutting tool, and mitigated the excessive growth of built-up edge (BUE), which improved the tool life and machined surface integrity. By analyzing the machined surface at the end of TC and MAC, it was found that the surface roughness at the end of MAC was reduced by 22.4 %. Meanwhile, the cavity, side flow and debris of BUE, which tend to occur in the machined surface during the TC process, are effectively suppressed after MAC. Furthermore, Microstructural analysis of the machined surface indicated an enhancement in the dislocation density on the machined surface layer, suggesting the magnetoplastic effect of the magnetic field on GH4169 alloy.

Correct Criterion of Crustal Failure Driven by Intense Magnetic Stress in Neutron Stars

Magnetar outbursts are powered by an intense magnetic field. The phenomenon has recently drawn significant attention because of a connection to some fast radio bursts that has been reported. Understanding magnetar outbursts may provide the key to mysterious transient events. The elastic deformation of the solid crust due to magnetic field evolution accumulates over a secular timescale. Eventually, the crust fractures or responds plastically beyond a particular threshold. Determination of the critical limit is required to obtain the shear strain tensor in response to magnetic stress. In some studies, the tensor was substituted with an approximate expression determined algebraically from the magnetic stress. This study evaluated the validity of the approximation by comparing it with the strain tensor obtained through appropriate calculations. The differential equations for the elastic deformation driven by the magnetic field were solved. The results indicated that the approximation did not represent the correct strain tensor value, in both magnitude and spatial profile. Previous evolutionary calculations based on spurious criteria are likely to overestimate the magnitude of the strain tensor, and crustal failure occurs on a shorter timescale. Therefore, revisiting evolutionary calculations using the correct approach is necessary. This study is essential for developing the dynamics of crustal fractures and the magnetic field evolution in a magnetar.

Effect of the Magnetic Field, Electric Field, and Light Intensity on the Parameters of Recombination Waves in Silicon

Effect of the Magnetic Field, Electric Field, and Light Intensity on the Parameters of Recombination Waves in Silicon

Morphology-dependent magnetic hyperthermia characteristics of Fe3O4 nanoparticles

Magnetic hyperthermia therapy (MHT) represents an innovative approach to cancer treatment, harnessing the therapeutic capabilities of magnetic nanoparticles. Fe3O4 nanoparticles are often considered ideal candidates for MHT because of their biocompatibility. However, the clinical application of Fe3O4 nanoparticles is hindered by their low heating efficiency and concerns regarding potential toxicity linked to the high concentrations required to achieve therapeutic effects. In this study, two unique structures, hollow spherical and nanoflower Fe3O4, were successfully synthesized to enhance their magnetothermal conversion efficiency. The results indicate that Fe3O4 nanoflowers exhibit an intrinsic loss power (ILP) value of 6.52, which is 1.83 times greater than the ILP of hollow spherical Fe3O4 (3.55), indicating its enhanced potential for MHT applications. The COMSOL simulation demonstrated that higher magnetic field frequencies and intensities elevate tissue temperature and damage in tumor cells, particularly at 100 kHz and 400 kHz, with tumor tissue damage scores rising to 0.28 and 0.93, respectively. Shorter heating durations, such as 6 min, minimize harm to healthy tissue and are ideal for treatments requiring multiple sessions. After 12 min, tumor scores rose to 0.85, while normal tissue scores were 0.34, suggesting that longer durations improve therapeutic effects on tumors but also heighten the risk to healthy cells. This research provides a scientific foundation for selecting materials in the context of MHT for cancer treatment, potentially paving the way for more effective and safer therapeutic strategies.

A VLA Study of Newly Discovered Southern Latitude Nonthermal Filaments in the Galactic Center: Polarimetric and Magnetic Field Properties

A population of structures unique to the Galactic Center (GC), known as the nonthermal filaments (NTFs), has been studied for over 40 yr, but much remains unknown about them. In particular, there is no widely accepted and unified understanding for how the relativistic electrons illuminating these structures are generated. One possibility is that there are compact and extended sources of cosmic rays, which then diffuse along magnetic flux tubes leading to the illumination of the NTFs through synchrotron emission. In this work, we present and discuss the polarimetric distributions associated with a set of faint NTFs in the GC that have only been studied in total intensity previously. We compare the derived polarized intensity, rotation measure, and intrinsic magnetic field distributions for these structures with the results obtained for previously observed GC NTFs. The results are then used to enhance our understanding of the large-scale polarimetric properties of the GC. We then use the derived polarimetric distributions to constrain models for the mechanisms generating the relativistic electrons that illuminate these structures.

Paleomagnetic Secular Variations in North Greenland Around 81°N Over the Last 6,000 Years

AbstractWe investigate full vector paleomagnetic changes recorded in high‐resolution sediments of Petermann Fjord, North Greenland, deposited over the last 6 kyr, in the context of the recent rapid changes in the geomagnetic field. A Paleomagnetic Secular Variation (PSV) stack (inclination, declination, and relative paleointensity) was reconstructed using four marine sediment cores with an independent age model constrained by seven radiocarbon ages. Magnetic investigations demonstrate that the paleomagnetic signal is carried by low coercivity ferrimagnetic minerals and is well reproduced in all cores, attesting to the quality and reliability of the paleomagnetic recording of these sediments. This signal is broadly consistent in directional changes with distant records in North America and the northern North Atlantic at centennial and millennial timescales, and has millennial scale intensity variations that are consistent with model predictions. The offset between a magnetization age determined through comparison with a northern North Atlantic PSV reference curve, GREENICE, and the radiocarbon age model indicates either a reasonable lock‐in depth of magnetization (∼11 cm from the coretop) or centennial‐scale reservoir age variation through time in the fjord. Reconstructed virtual geomagnetic pole (VGP) migration for the last 6 kyr shows that the recent migration of the magnetic North Pole is consistent with secular paleomagnetic variations on geologic timescales. Our results suggest that magnetic field intensity variations (temporal and spatial) are linked to magnetic flux lobe dynamics and influence the VGP migration.

Effects of pulsed magnetic field intensity on the freezing rate and heat loads reduction of harvested mango and tomato

PurposeFresh fruits and vegetables (FV) are crucial global food resources, but the presence of heat loads during harvest adversely impacts their shelf life. While freezing technology provides an effective means of removing heat loads, it is an energy-intensive process and may consequently prove too costly for practical business viability. The growing interest in utilizing magnetic field (MF) technology during the freezing of fresh FV enhances the freezing rate and rapidly removes the heat loads of products.Design/methodology/approachIn the present study, pulsed magnetic field (PMF) pretreatment employing specific field strengths (9 T, 14 T and 20 T) was examined as a preliminary step before freezing mango and tomato and compared to the conventional freezing method (untreated) at − 18 °C.FindingsPMF pretreatment prior to freezing demonstrated a noteworthy enhancement in freezing rate by around 10 and 12% when compared with the conventional (untreated) freezing, which exhibited freezing rates of −0.08 °C/min and −1.10 °C/min for mango and tomato, respectively. The PMF pretreatment (at 20 T) provided a higher freezing rate (at p = 0.05) than the conventional freezing method reduced heat loads amounting to 1.1 × 107 J/kg oC and 2.9 × 106 J/kg oC, significantly (at p = 0.05) from mango and tomato, respectively. These reductions in heat loads were approximately more than 5% of the calculated heat loads removed during conventional freezing.Research limitations/implicationsMango and tomato samples were only tested; the results may lack generalizability. Therefore, researchers are encouraged to test for other products for further studies.Practical implicationsThe paper includes implications for the development of a rapid freezing technique, the development of “pulsed magnetic field” and for eliminating the problem associated with conventional (slow) freezing.Originality/valueThe study holds significance for the production of postharvest freezing technology, providing insightful information on the PMF-assisted freezing of cellular foods.

Systematic simulation of tumor cell invasion and migration in response to time-varying rotating magnetic field.

Cancer invasion and migration play a pivotal role in tumor malignancy, which is a major cause of most cancer deaths. Rotating magnetic field (RMF), one of the typical dynamic magnetic fields, can exert substantial mechanical influence on cells. However, studying the effects of RMF on cell is challenging due to its complex parameters, such as variation of magnetic field intensity and direction. Here, we developed a systematic simulation method to explore the influence of RMF on tumor invasion and migration, including a finite element method (FEM) model and a cell-based hybrid numerical model. Coupling with the data of magnetic field from FEM, the cell-based hybrid numerical model was established to simulate the tumor cell invasion and migration. This model employed partial differential equations (PDEs) and finite difference method to depict cellular activities and solve these equations in a discrete system. PDEs were used to depict cell activities, and finite difference method was used to solve the equations in discrete system. As a result, this study provides valuable insights into the potential applications of RMF in tumor treatment, and a series of in vitro experiments were performed to verify the simulation results, demonstrating the model's reliability and its capacity to predict experimental outcomes and identify pertinent factors. Furthermore, these findings shed new light on the mechanical and chemical interplay between cells and the ECM, offering new insights and providing a novel foundation for both experimental and theoretical advancements in tumor treatment by using RMF.

Simulation analysis and hydrodynamic performance optimization of small MHD thruster based on improved I-bridge structure

Abstract Magnetic hydrodynamic drive (MHD) generates thrust by the coupling interaction of three fields: flow field-electric field-magnetic field. Because this propulsion method has no propeller or mechanical structure, it has the advantages of quiet, simple structure, easy operation, flexible layout, and difficult to detect. This is the current research hot spot. In order to meet the needs of miniaturized silent propulsion, this paper selects a linear internal magnetic thruster for research and analysis and improves the design of an I-shaped magnetic bridge structure. Firstly, the thrust and efficiency of the thruster under ideal conditions are calculated, and the thruster model is established. The conclusion is that the I-shaped magnetic bridge can increase the magnetic field intensity of the channel and significantly improve the MHD propulsion efficiency. At the same time, it is found that MHD thruster can reduce noise during operation, but the current required for propulsion is large, and seawater electrolysis will occur, which has a certain impact on the environment. Finally, the problems of small direct drive MHD propulsion are analyzed, and the future development direction of MHD propulsion is prospected.

Experimental investigation of heat transfer enhancement, thermal efficiency, and pressure drop in forced convection of magnetic hybrid nanofluid (Fe₃O₄/TiO₂) under varied magnetic field strengths and waveforms

Applying a magnetic field to influence convective flow of ferrofluids has become an efficient method for enhancing heat transfer in thermal systems, particularly in straight tubes. This study investigates the heat transfer properties of Fe₃O₄/TiO₂ nanofluids within a heated copper tube under varied magnetic field strengths and waveforms. Optimal magnetic field conditions were determined at 4 V and 60 Hz across all waveform types, as higher frequencies and voltages increased magnetic field intensity, thereby reducing heat transfer rates. Magnetic waveforms exerted differential influences on pressure drop, indicating varied nanoparticle alignment and turbulence levels, impacting fluid flow dynamics and viscosity. Higher nanoparticle concentration (0.1% vol) correlated with increased pressure drops across sine, square, and triangular waveforms, suggesting heightened flow resistance and potential nanoparticle agglomeration, thus reducing thermal efficiency. Conversely, lower concentrations exhibited enhanced thermal performance due to improved nanoparticle dispersion and reduced thermal resistance. At 0.1% vol, heat transfer enhancement without a magnetic field was 16.5%. The introduction of magnetic field waveforms attenuated this enhancement: 15.3% (sine), 13.26% (square), and 12.59% (triangular). Conversely, at lower volume fractions, heat transfer enhancements with magnetic fields exceeded those without at 0.05% vol, enhancements were 20.92% (sine), 21.3% (square), and 21.34% (triangular); at 0.025% vol, enhancements were 22.07% (sine), 22.3% (square), and 21.32% (triangular); at 0.0125% vol, enhancements were 27.87% (sine), 28.21% (square), and 26.74% (triangular); and at 0.0065% vol, enhancements were 22.24% (sine), 22.3% (square), and 24.49% (triangular).

Magneto-Thermoelastic Principal Parameter Resonance of a Functionally Graded Cylindrical Shell with Axial Tension

The principal parameter resonance of a ferromagnetic functionally graded (FG) cylindrical shell under the action of axial time-varying tension in magnetic and temperature fields is investigated. The temperature dependence of physical parameters for functionally graded materials (FGMs) is considered. Meanwhile, the tension bending coupling effect is eliminated by introducing the physical neutral surface. The kinetic and strain energies are gained with the Kirchhoff–Love shell theory. Based on the nonlinear magnetization characteristics of ferromagnetic materials, the electromagnetic force acting on the shell is calculated. The nonlinear vibration equations are obtained through Hamilton’s principle. Afterward, the vibration equations are discretized and solved by Galerkin and multiscale methods, respectively. The stability criterion for steady-state motion is established utilizing Lyapunov stability theory. After example analysis, the effects of magnetic field intensity, temperature and power law index on the static deflection are elucidated. Subsequently, the impacts of these parameters, as well as axial tension, on the amplitude-frequency characteristics, resonance amplitude, and multiple solution regions are discussed explicitly. Results indicate that the stiffness can be enhanced due to the generation of static deflection. The amplitude decreases with increasing magnetic field intensity, temperature, and power law index. When the magnetic field intensity surpasses a threshold, the resonance phenomenon disappears.

Preparation of Cu nanolayers by magnetic field-assisted electrodeposition and research on the nucleation and growth mechanism

Electrodeposition technology is widely used in the surface treatment of copper foil, and the core of this technology is roughening and curing treatment. During the electrodeposition process, the deposited layers often exhibits some problems, such as coarse grain size, uneven thickness and difficult control of crystal morphology. The magnetohydrodynamic (MHD) effect of magnetic field can obviously control the electrodeposition of Cu and improve the micro-morphology and performance of deposited layers. In this paper, Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV) and Chronocoulometry (CC) curves were adopted to investigate the electrochemical behavior of deposited Cu in ultra-high acidity sulfate systems under different magnetic field conditions. The nucleation and growth mechanism were discussed, and the micro-morphology of deposited layers was analyzed. The results show that the electrodeposition of Cu follows the three-dimensional (3D) growth mechanism of progressive nucleation and diffusion control under the static condition, and the deposits appear cylindrical shape formed by spherical agglomerated. The magnetic field significantly improves the mass transfer rate, and the deposited layers will be more uniform and dense, following 3D growth mechanism under the electrochemical control. With the increasing of magnetic field intensity, the nucleation mechanism gradually shifts from progressive to transient nucleation. At the early stage of nucleation, the high-intensity magnetic field can significantly increase the number of grains and refine them, obtaining uniform and dense deposited nanolayers.

Microwave diagnostics of flare plasma by the direct fitting method based on data from the Siberian Radioheliograph

In this paper, we analyze images and the frequency spectrum of microwave emission in the maximum of brightness distribution in the January 20, 2022 and July 16, 2023 flares recorded by the Siberian Radioheliograph in the 3–6 GHz and 6–12 GHz ranges. We use the obtained spectrum data for radio diagnostics of magnetic field strength and orientation, plasma density, and parameters of accelerated particles in a radio source. The radio diagnostics is carried out by a method based on minimizing the functional containing the intensities of theoretically calculated and observed frequency spectra of left-polarized and right-polarized emission. Since the form of such a multidimensional functional is quite complex, and it is not possible to minimize it by standard approaches, we employ a genetic minimization method. The radio diagnostics allows us to determine features of the dynamics of the magnetic field intensity and orientation, as well as the density and the energy spectral index of non-thermal electrons in the region of maximum brightness of the radio source. We have found that during the growth phase of the main radiation peaks the magnetic field decreases, whereas during the decay phase, on the contrary, it increases. The rate of these changes varies from a few G/s to 11 G/s for the January 20, 2022 flare and is about 1 G/s for the July 16, 2023 flare.

Микроволновая диагностика вспышечной плазмы методом фитирования по данным Cибирского радиогелиографа

In this paper, we analyze images and the frequency spectrum of microwave emission in the maximum of brightness distribution in the January 20, 2022 and July 16, 2023 flares recorded by the Siberian Radioheliograph in the 3–6 GHz and 6–12 GHz ranges. We use the obtained spectrum data for radio diagnostics of magnetic field strength and orientation, plasma density, and parameters of accelerated particles in a radio source. The radio diagnostics is carried out by a method based on minimizing the functional containing the intensities of theoretically calculated and observed frequency spectra of left-polarized and right-polarized emission. Since the form of such a multidimensional functional is quite complex, and it is not possible to minimize it by standard approaches, we employ a genetic minimization method. The radio diagnostics allows us to determine features of the dynamics of the magnetic field intensity and orientation, as well as the density and the energy spectral index of non-thermal electrons in the region of maximum brightness of the radio source. We have found that during the growth phase of the main radiation peaks the magnetic field decreases, whereas during the decay phase, on the contrary, it increases. The rate of these changes varies from a few G/s to 11 G/s for the January 20, 2022 flare and is about 1 G/s for the July 16, 2023 flare.

Compact Electron Paramagnetic Resonance on a Chip Spectrometer Using a Single Sided Permanent Magnet.

Electron paramagnetic resonance (EPR) spectroscopy provides information about the physical and chemical properties of materials by detecting paramagnetic states. Conventional EPR measurements are performed in high Q resonator using large electromagnets which limits the available space for operando experiments. Here we present a solution toward a portable EPR sensor based on the combination of the EPR-on-a-Chip (EPRoC) and a single-sided permanent magnet. This device can be placed directly into the sample environment (i.e., catalytic reaction vessels, ultrahigh vacuum deposition chambers, aqueous environments, etc.) to conduct in situ and operando measurements. The EPRoC reported herein is comprised of an array of 14 voltage-controlled oscillator (VCO) coils oscillating at 7 GHz. By using a single grain of crystalline BDPA, EPR measurements at different positions of the magnet with respect to the VCO array were performed. It was possible to create a 2D spatial map of a 1.5 mm × 5 mm region of the magnetic field with 50 μm resolution. This allowed for the determination of the magnetic field intensity and homogeneity, which are found to be 254.69 mT and 700 ppm, respectively. The magnetic field was mapped also along the vertical direction using a thin film a-Si layer. The EPRoC and permanent magnet were combined to form a miniaturized EPR spectrometer to perform experiments on tempol (4-hydroxy-2,2,6,6-teramethylpiperidin-1-oxyl) dissolved in an 80% glycerol and 20% water solution. It was possible to determine the molecular tumbling correlation time and to establish a calibration procedure to quantify the number of spins within the sample.