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This study introduces a novel volume coil design that features two slotted end-plates connected by six rungs, resembling the traditional birdcage coil. The end rings are equipped with six evenly distributed circular slots, inspired by Mansfield's cavity resonator theory, which suggests that circular slots can generate a baseline resonant frequency. One notable advantage of this proposed coil design is its reduced reliance on electronic components compared to other volume coils, making it more efficient. Additionally, the dimensions of the coil can be theoretically computed in advance, enhancing its practicality. To evaluate the performance and safety of the coil, electromagnetic field and specific absorption rate simulations were simulated using a cylindrical saline phantom and the finite element method. Furthermore, a transceiver coil prototype optimized for 7 Tesla and driven in quadrature was constructed, enabling whole-body imaging of rats. The resonant frequency of the coil prototype obtained through experimental measurements closely matched the theoretical frequency derived from Mansfield's theory. To validate the coil design, phantom images were acquired to demonstrate its viability and assess its performance. These images also served to validate the magnetic field simulations. The experimental results aligned well with the simulation findings, confirming the reliability of the proposed coil design. Importantly, the prototype coil showcased significant improvements over a similarly-sized birdcage coil, indicating its potential for enhanced performance. The noise figure was lower in the prototype versus the birdcage coil (NFbirdcage-NFslotcage= 0.7). Phantom image data were also used to compute the image SNR, giving SNRslotcage/SNRbirdcage= 34.36/24.34. By proving the feasibility of the coil design through successful rat whole-body imaging, the study provides evidence supporting its potential as a viable option for high-field MRI applications on rodents.

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Magnetomotive ultrasound (MMUS) stands out as a promising and effective ultrasound-based method for detecting magnetic nanoparticles (MNPs) within tissues. This innovative technique relies on the precise estimation of micrometric displacements induced by the interaction of an external magnetic field with MNPs. Pulsed MMUS has emerged as a strategic alternative to address limitations associated with harmonic excitation, such as heat generation in amplifiers and coils, frequency-dependent tissue mechanical responses, and prolonged magnetic field rise times. Despite the growing interest in MMUS, the devices conventionally employed to excite the coil are not specifically tailored to generate intense magnetic fields while minimizing interference with the transient behavior of induced displacements. To bridge this gap, our work introduces the design and fabrication of two pulse generators: one based on a capacitor-discharge circuit and the other on a resonant-inverter circuit. We evaluated the performance of these pulse generators by considering parameters such as the magnetic field generated, rise and fall times, and their ability to supply sustained current for varied pulse widths across different pulse repetition frequencies. Furthermore, we carried out a practical MMUS implementation using tissue-mimicking phantoms, demonstrating the capability of both devices to achieve magnetic fields of up to 1 T and average displacements of 25 µm within the phantom. In addition, we estimated the shear wave velocity, effective shear modulus, and their temperature-dependent variations. Our findings highlight the versatility and efficacy of the proposed pulse generators and emphasize their potential as low-cost platforms for theranostic applications, enabling the assessment of targeted entities within biological tissues.

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The detection of magnetic fields by animals is known as magnetoreception. The ferromagnetic hypothesis explains magnetoreception assuming that magnetic nanoparticles are used as magnetic field transducers. Magnetite nanoparticles in the abdomen of Apis mellifera honeybees have been proposed in the literature as the magnetic field transducer. However, studies with ants and stingless bees have shown that the whole body of the insect contain magnetic material, and that the largest magnetization is in the antennae. The aim of the present study is to investigate the magnetization of all the body parts of honeybees as has been done with ants and stingless bees. To do that, the head without antennae, antennae, thorax, and abdomen obtained from Apis mellifera honeybees were analyzed using magnetometry and Ferromagnetic Resonance (FMR) techniques. The magnetometry and FMR measurements show the presence of magnetic material in all honeybee body parts. Our results present evidence of the presence of biomineralized magnetite nanoparticles in the honeybee abdomen and, for the first time, magnetite in the antennae. FMR measurements permit to identify the magnetite in the abdomen as biomineralized. As behavioral experiments reported in the literature have shown that the abdomen is involved in magnetoreception, new experimental approaches must be done to confirm or discard the involvement of the antennae in magnetoreception.

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Nuclear magnetic resonance (NMR) longitudinal rotating frame relaxation time (T1ρ), rarely used in low-field NMR, can be more effective than conventional T1 and T2 relaxation times to differentiate polymorphic forms of solid pharmaceuticals. This could be attributed to T1ρ sensibility to structural and molecular dynamics that can be enhanced by changing the strength of the oscillating magnetic field (B1) of spinlock pulses. Here, we compared the capacity of T1, T2, and T1ρ to differentiate inactive (A) and active (C) crystalline forms of the World Health Organization essential drug Mebendazole. The results showed that T1 and T2 values of both forms were statistically identical at 0.47 T. Conversely, T1ρ of both forms measured with weak spinlock B1 fields, ranging from 0.08 to 0.80 mT were statistically different in the same spectrometer. The T1ρ also has the limit of detection to detect the presence of at least 10% of inactive A form in the active C form. Therefore, T1ρ, measured with weak spinlock B1 fields can be an effective, streamlined, and complementary approach for characterizing not only solid active pharmaceutical ingredients but other solid-state materials as well.

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Magnetotactic bacteria are microorganisms that produce intracellular magnetic nanoparticles organized in chains, conferring a magnetic moment to the bacterial body that allows it to swim following the geomagnetic field lines. Magnetotactic bacteria usually display two swimming polarities in environmental samples: the South-seeking (SS) polarity and the North-seeking (NS) polarity, characterized by the bacteria swimming antiparallel or parallel to the magnetic field lines, respectively. It has been observed that in the presence of inhomogeneous magnetic fields, NS magnetotactic bacteria can change their swimming polarity to SS or vice versa. The present study analyzes populations of NS cocci obtained from SS cocci isolated in the presence of a magnet. The aim was to study differences in the swimming characteristics and magnetic moment among both populations of cocci. For that, trajectories were recorded and the velocity and angle among the velocity and the applied magnetic field were calculated. In addition, micrographs from both SS and NS cocci were obtained and their magnetosomes were measured to analyze their length, width, aspect ratio and magnetic moment, to finally obtain the magnetic moment for each coccus. The results showed the following properties of NS relative to SS cocci: higher velocities, narrow bacterial magnetic moment distribution, higher dispersion in the distribution of angles among the velocity and the applied magnetic field and lower magnetic field sensibility. Those differences cannot be explained by the simple change in magnetic polarity of the magnetosome chain and can be related to the existence of an active magnetoreceptive process in magnetotactic bacteria.

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A feature in neurodegenerative disorders is the loss of neurons, caused by several factors including oxidative stress induced by reactive oxygen species (ROS). In this work, static magnetic field (SMF) was applied in vitro to evaluate its effect on the viability, proliferation, and migration of human neuroblastoma SH-SY5Y cells, and on the toxicity induced by hydrogen peroxide (H2O2), tert-butyl hydroperoxide (tBHP), H2O2/sodium azide (NaN3) and photosensitized oxidations by photodynamic therapy (PDT) photosensitizers. The SMF increased almost twofold the cell expression of the proliferation biomarker Ki-67 compared to control cells after 7 days of exposure. Exposure to SMF accelerated the wound healing of scratched cell monolayers and significantly reduced the H2O2-induced and the tBHP-induced cell deaths. Interestingly, SMF was able to revert the effects of NaN3 (a catalase inhibitor), suggesting an increased activity of catalase under the influence of the magnetic field. In agreement with this hypothesis, SMF significantly reduced the oxidation of DCF-H2, indicating a lower level of intracellular ROS. When the redox imbalance was triggered through photosensitized oxidation, no protection was observed. This observation aligns with the proposed role of catalase in cellular proctetion under SMF.  Exposition to SMF should be further validated in vitro and in vivo as a potential therapeutic approach for neurodegenerative disorders.

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BACKGROUND: Fibromyalgia is a syndrome characterized by generalized chronic pain and tenderness in specific areas. Photobiomodulation therapy (PBMT) using low-level laser therapy and/or light emitting diode therapy is an electrophysical agent that can be used alone or together with a static magnetic field (PBMT-sMF) to promote analgesia in several health conditions. Little evidence exists regarding the effects of using PBMT and PBMT-sMF in patients with fibromyalgia; this evidence is conflicting. AIM: We aimed to investigate the effects of using PBMT-sMF versus a placebo on reduction of the degree-of-pain rating, impact of fibromyalgia, pain intensity, and satisfaction with treatment in patients with fibromyalgia. DESIGN: A prospectively registered, monocentric, randomized placebo-controlled trial, with blinding of patients, therapists, and assessors, was performed. SETTING: The study was conducted at the Laboratory of Phototherapy and Innovative Technologies in Health (LaPIT) in Brazil, between March and October 2020. POPULATION: Ninety female patients with fibromyalgia were randomized to undergo either PBMT-sMF (N.=45) or placebo (N.=45) treatment. METHODS: Patients from both groups received nine treatment sessions, three times a week, for 3 weeks. Clinical outcomes were collected at baseline, the end of treatment, and at the follow-up appointment 4 weeks post-treatment. The primary outcome was the degree-of-pain rating, measured by the reduction of the tender point count. RESULTS: A decrease in the degree-of-pain rating was observed in patients allocated to the PBMT-sMF group, decreasing the number of tender points when compared to placebo group at the end of treatment (P<0.0001) and at the follow-up assessment (P<0.0001). Patients did not report any adverse events. CONCLUSIONS: PBMT-sMF is superior to placebo, supporting its use in patients with fibromyalgia. CLINICAL REHABILITATION IMPACT: PBMT-sMF might be considered an important adjuvant to the treatment regimens of patients with fibromyalgia.

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This study aimed at estimating cultivation conditions to enable Yarrowia lipolytica NNRL Y-1095 to produce extracellular lipase and at evaluating the influence of magnetic fields (MF) on the lipase production and on its catalytic conditions. Culture conditions of carbon sources and surfactant defined to produce extracellular lipase were 10 g L-1 glucose, 15 g L-1 olive oil and 2 g L-1 Triton X-100. The highest lipase activity (34.8 U mL-1) was reached after 144 h when MFs were applied from 72 to 144 h of culture. It corresponds to an increase of 287.5% by comparison with the highest lipase activity in the control culture. MF application from 72 to 144 h did not change the optimal temperature of lipase, which was 37 °C, by comparison with the control. However, the optimal pH of the control was 7.0 while the one of lipase produced with MF was 8.0. Findings highlighted that the presence of MFs led to increase in synthesis of lipase by Y. lipolytica, with changes in the catalytic profile. This is one of the first studies of MF application to Y. lipolytica NRRL Y-1095 cultures to produce lipase.

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We present a theoretical study of the surface magnon-polaritons at an interface formed by vacuum and a gyromagnetic medium (that can be either ferromagnetic or antiferromagnetic), when there is a graphene layer deposited between the media at the interface and a magnetic field is applied perpendicular to the interface. The retarded-mode dispersion relations are calculated by considering a superposition of transverse magnetic and transversal electric electromagnetic waves in both media. Our results reveal the appearance of the surface magnon-polariton modes (with frequencies typically of a few GHz) that do not exist in the absence of graphene at the interface. Also, a typical magnon-polariton dispersion relation with damping is revealed, including a resonant frequency that depends on the applied magnetic field. The effects of varying the doping levels, which modify the Fermi energies in the graphene, and varying the perpendicular applied magnetic field are presented, revealing a strong influence exerted by the presence of graphene on the surface magnon-polariton modes. Other effects include the control of the slope of the dispersion curves (with respect to the in-plane wave vector) for the modes as the Fermi energies of the graphene sheet are changed and the distinctive localization properties for the emerging surface modes.

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This study aimed to analyze the effect of magnetic field (MF) application on the metabolism of Synechococcus elongatus PCC 7942. Concentrations of biomass, carbohydrate, protein, lipid, and photosynthetic pigments (chlorophyll-a, C-phycocyanin, allophycocyanin and phycoerythrin) were determined. In cultures with MF application (30 mT for 24 h d-1), there were increases of 47.5% in total protein content, 87.4% in C-phycocyanin, and 332.8% in allophycocyanin contents, by comparison with the control. Allophycocyanin is the most affected pigment by MF application. Therefore, its biosynthetic route was investigated, and four genes related to its synthesis were found. However, the analysis of the gene expression showed no statistical differences from the control culture, which suggests that induction of such genes may occur soon after MF application with consequent stabilization over time. MF application may be a cost-effective alternative to increase production of compounds of commercial interest by cyanobacteria.

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Magnetic field (MF) effects have been reported in plants' growth, seed germination, gene expression, and water consumption. Accordingly, magnetic treatments have been proposed as a sustainable alternative to improve yields. Nevertheless, a comprehensive quantitative assessment is needed to understand whether their effects are general, species-specific, or dependent on the experimental setting. We conducted a multilevel meta-analysis of 45 articles that studied 29 different plant species. A positive and neutral effect of a nonuniform MF was found on fresh weight and germination rate, respectively. A significant association was found between a uniform MF and germination. These results suggest that MFs improve plant growth. However, the effects are highly dependent on the experimental setting. This opens exciting questions about the biophysical mechanisms underlying the perception and transduction of this environmental cue and about the possible translation to agricultural practices. © 2023 Bioelectromagnetics Society.

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The application of magnetic fields (MF) has attracted the attention of researchers due to their efficiency to change cell metabolism. Chlamydomonas reinhardtii is a biotechnologically useful microalga with versatile metabolism that may be a valuable organism to study the effects of the MF in biology. Therefore, two C. reinhardtii strains, one with cell wall (2137) and other which lacks the cell wall (Wt-S1-cc4694), were evaluated that a new sensitivity factor in the analysis could be included. Comparative studies were undertaken with the two C. reinhardtii strains under the MF intensities of 0.005 mT (terrestrial MF - control), 11  and 20 mT. Results indicated that the physical cell wall barrier protected cells against the MF applied during the assays. Only with the highest MF applied (20 mT) a slight increase in lipid concentration in the cell wall strain was detected. The lowest growth of the strain that lacks cell wall (Wt-S1) indicated that these cells are under a negative effect. To cope with the two MF stresses conditions, Wt-S1 cells produced more pigments (chlorophylls and carotenoids) and lipids and enhanced the antioxidant defense system. The raise of these compounds under MF could potentially have a positive biotechnological impact on algal biomass.

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Objective:Magnetic fluid hyperthermia (MFH) is a still experimental technique found to have a potential application in the treatment of cancer. The method aims to reach around 41 °C-47 °C in the tumor site by exciting magnetic nanoparticles with an externally applied alternating magnetic field (AMF), where cell death is expected to occur. Applying AMFs with high spatial resolution is still a challenge. The AMFs from current and prospective MFH applicators cover relatively large areas; being not suitable for patients having metallic implants near the treatment area. Thus, there will be a clinical need for smaller magnetic field applicators. To this end, a laparoscopic induction heater (LIH) and a transrectal induction heater (TRIH) were developed.Methods:Miniature 'pancake' coils were wound and inserted into 3D printed enclosures. Ovarian (SKOV-3, A2780) and prostate (PC-3, LNCaP) cancer cell lines were used to evaluate the instruments' capabilities in killing cancer cellsin vitro, using Synomag®-D nanoparticles as the heat mediators. NIH3T3 normal cell lines were also used with both devices to observe if these cells tolerated the conditions applied.Results:Magnetic field intensities reached by the LIH and TRIH were 42.6 kA m-1at 326 kHz and 26.3 kA m-1at 303 kHz, respectively. Temperatures reached in the samples were 41 °C by the LIH and 43 °C by the TRIH. Both instruments successfully accomplished killing cancer cells, with minimal effects on normal cells.Conclusion:This work presents the first line of handheld medical induction heaters and have the potential to be a complement to existing cancer therapies.Significance:These instruments could enable the development of MFH modalities that will facilitate the clinical translation of this thermal treatment.

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A 10-week-old male, Xoloitzcuintle (Mexican hairless dog), weighing 8.9 kg was presented after its owner accidentally stepped on its paw. The dog presented with acute pain, inflammation and grade IV lameness in the right hind paw. A complete transverse fracture in the right proximal tibia was diagnosed from radiography. The dog underwent a minimally invasive plate osteosynthesis (MIPO) procedure. After surgery, photobiomodulation therapy combined with static magnetic field (PBMT-sMF) was applied twice daily for 21 days. A multi-wavelength PBMT-sMF device was applied at three sites using different frequencies: proximal and distal of the fracture zone (3000 Hz, 40.35 J per site, and 300 s per site) and in the fracture zone (250 Hz, 39.11 J and 300 s per site). Follow up radiographies were performed after surgery and treatment with PBMT-sMF. Eighteen days post-surgery the healing process of bone was advanced. Fifty-five days post-surgery the callus was enlarged. In addition, radiographic union and clinical union was evidenced by closure of the fracture gap. This case report has reported the use of PBMT-sMF in order to accelerate and improve bone healing following a MIPO procedure on a complete transverse fracture in the proximal tibia of a puppy.

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The physicochemical and structural characteristics of the magnetic materials can be modulable due to exposition to a magnetic field, which allows, for example, to enhance its adsorption performance. In this sense, this study describes the preparation of magnetic beads of alginate/polypyrrole/ZnFe2O4 (Alg/PPy/ZnFe2O4) and investigates the effect of an external magnetic field (EMF) on their adsorption performance towards two overconsumed drugs, acetaminophen (ACT) and ibuprofen (IBU). Characterization analyses confirmed the composite formation and magnetic nature of Alg/PPy/ZnFe2O4. Conversely to the pristine beads (Alg/PPy), the presence of an EMF altered the swelling and pHPZC behavior of the magnetic beads, indicating that these properties are affected by this external stimulus. Batch experiments revealed that the amount of ACT and IBU adsorbed by Alg/PPy/ZnFe2O4 in 60-70 min is appreciably high (106.7 ad 108.2 mg/g). The presence of an EMF modulated the structure of Alg/PPy/ZnFe2O4 beads enhancing their adsorption capacity towards ACT and IBU by 14% and 12% compared to Alg/PPy. Kinetic analysis revealed that the adsorption of both drugs on Alg/PPy/ZnFe2O4 followed a pseudo-second-order. Besides, the adsorption mechanism was fitted by the Freundlich isotherm. Reuse experiments showed that the magnetic beads keep a high adsorption capacity for both drugs even after ten consecutive reuse cycles. The results presented here suggest that magnetic-responsive materials like Alg/PPy/ZnFe2O4 are prominent and modulable tools for improving the treatment of water/wastewater containing this class of contaminants.

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Studies have shown that psychotropic drugs change rat behavior in the elevated plus-maze test (EPM). This study investigated whether static magnetic fields could alter alprazolam-induced rat behavior in the EPM. 66 male Wistar rats (270-300 g weight) were assigned to one of the following groups: Sham Magnetic + Saline (SMS), North Pole + Saline (NPS), South Pole + Saline (SPS), Sham magnetic + alprazolam (SMA), NP + alprazolam (NPA), and SP + alprazolam (SPA). After five days of static magnetic stimulation (3200 Gauss), they received alprazolam or saline (1 mg/kg), and their behavior was evaluated. Two-way ANOVA and Holm-Sidak post-hock were used, with a significant P value of <0.05. The SMA and NPA groups showed an increased number of entries and time in the open arms compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 6.43 and F(2,61) = 3.72, respectively]. The SMA and NPA groups showed increased head dipping and end-arm activity compared with the SMS group. SPA showed a decrease in these measures when compared to SMA [F(2,61) = 3.37 and [F(2,61) = 4.72, respectively]. These results show that the south magnetic pole of a static magnetic field blocked the alprazolam effect in the space-time variables of the open arms and ethological anxiolytic-like behavior in the EPM.

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Condition monitoring of synchronous generators through non-invasive methods is widely requested by maintenance teams for not interfering the machine operation. Among the techniques used, external magnetic field monitoring is a recent strategy with great potential for detecting incipient faults. In this context, this paper proposes the application of a simple strategy with low computational cost to process data of external magnetic field time derivative signals for the purposes of condition monitoring and fault detection in synchronous machines. The information of interest is extracted from changes in the magnetic signature of the synchronous generator, obtained from frequency spectra of monitored signals using induction magnetic field sensors. The process forms a set of time series that reflects constructive and operational characteristics of the machine. The Shewhart control chart method is applied for anomaly detection in these time series, allowing the detection of changes in the machine magnetic signature. This method is employed in an algorithm for continuous condition monitoring of synchronous generators, presenting as output a global change indicator for the multivariable problem associated with magnetic signature monitoring. Correlation matrices are used to improve the algorithm response, filtering series with similar variation patterns associated with detected events. The proposed method is validated through tests on an experimental bench that allows the controlled imposition of faults in a synchronous generator. The proposed global change indicator allows the automatic detection of stator and rotor faults with the machine synchronized with the commercial power grid. The proposed methodology is also applied on data obtained from an equipment installed in a 305 MVA synchronous generator of a hydroelectric power plant where the evolution of an incipient fault, i.e., a mechanical vibration fault, has been detected.

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Glutathione (GSH) and peroxidase (POD) are biomolecules of interest in the global market; thus, it is desirable to seek ways to increase their production. Magnetic field (MF) application is one of the technologies used in cultivation that has shown promising results to increase bioproducts. Therefore, this study aimed at evaluating the influence of MFs on GSH and POD production by Saccharomyces cerevisiae ATCC 7754. Different periods of MF application (35 mT) were evaluated over 72 h. The highest GSH production was reached in 48 h of cultivation in assays MF 0-24 (155.32 ± 9.12 mg L-1) and MF 0-72 (149.27 ± 3.62 mg L-1), which showed an increase of 121.9 % and 113 %, respectively, by comparison with the control without any MF application. The highest POD activity was achieved when MFs were applied throughout the culture (36.31 U mg-1) and POD productivity of 0.72 U mg-1 h-1. MF application throughout cultivation proved to be a promising strategy since all responses increased, i.e., GSH concentration, GSH productivity, POD activity, and POD productivity increased 113.7 %, 113 %, 20.4 %, and 28.6 %, respectively. This study is one of the first to consider MFs as a viable and low-cost alternative to produce GSH and POD in bioprocesses.

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Several studies have shown that any magnetic field (MF) applied to microalgae modifies its cultivation conditions and may favor biomolecule production since it interacts with the microorganisms and affect their growth. As a result, there are changes in concentrations and compositions of biomass and biomolecules. This review aims at updating MF applications to microalga cultures that were reported by studies conducted in the last 5 years. It shows the main studies that reached positive results of carbohydrate, lipid, protein and pigment production. Effects of MFs may be positive, negative or null, depending on some factors, such as intensity, exposure time, physiological state of cells and application devices. Therefore, this review details cultivation conditions used for reaching high concentration of biomolecules, explains the action of MFs on microalgae and describes their applicability to the biorefinery concept.

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