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Occupational Medicine (Oxford, England) Apr 2022Many studies have investigated magnetic field exposure and the risks of motor neuron disease (MND). Meta-analyses have found positive associations but a causal...
BACKGROUND
Many studies have investigated magnetic field exposure and the risks of motor neuron disease (MND). Meta-analyses have found positive associations but a causal relationship has not been established.
AIMS
To investigate the risks of MND and occupational exposure to magnetic fields in a large UK cohort.
METHODS
Mortality of 37 986 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1987-2018. Employees were first employed in the period 1942-82 and were still in employment on the 1 November, 1987. Detailed calculations enabled estimates to be made of magnetic field exposures. Observed deaths were compared with expected numbers based on mortality rates for the general population of England and Wales and Poisson regression was used to calculate rate ratios (relative risks) for categories of lifetime, lagged (distant) and lugged (recent) magnetic field exposure.
RESULTS
Mortality from MND in the total cohort was similar to national rates (observed 69, expected 71.3, SMR 97, 95% CI 76-122). There were no statistically significant trends of risks increasing with lifetime, recent or distant magnetic field exposure, although positive associations were observed for some categories of recent exposure.
CONCLUSIONS
The study did not find that the cohort had elevated risks of MND as a consequence of occupational lifetime exposure to magnetic fields, although a possible role for recent exposures could usefully be investigated in other datasets.
Topics: Cohort Studies; Humans; Magnetic Fields; Motor Neuron Disease; Occupational Diseases; Occupational Exposure
PubMed: 34940878
DOI: 10.1093/occmed/kqab180 -
Nature Communications Nov 2022Rolling is a ubiquitous transport mode utilized by living organisms and engineered systems. However, rolling at the microscale has been constrained by the requirement of...
Rolling is a ubiquitous transport mode utilized by living organisms and engineered systems. However, rolling at the microscale has been constrained by the requirement of a physical boundary to break the spatial homogeneity of surrounding mediums, which limits its prospects for navigation to locations with no boundaries. Here, in the absence of real boundaries, we show that microswarms can execute rolling along virtual walls in liquids, impelled by a combination of magnetic and acoustic fields. A rotational magnetic field causes individual particles to self-assemble and rotate, while the pressure nodes of an acoustic standing wave field serve as virtual walls. The acoustic radiation force pushes the microswarms towards a virtual wall and provides the reaction force needed to break their fore-aft motion symmetry and induce rolling along arbitrary trajectories. The concept of reconfigurable virtual walls overcomes the fundamental limitation of a physical boundary being required for universal rolling movements.
Topics: Acoustics; Sound; Culture Media; Magnetic Fields; Motion
PubMed: 36446799
DOI: 10.1038/s41467-022-35078-8 -
Biosensors Mar 2022The magnetic manipulation of droplets is one of the emerging magnetofluidic technologies that integrate multiple disciplines, such as electromagnetics, fluid mechanics... (Review)
Review
The magnetic manipulation of droplets is one of the emerging magnetofluidic technologies that integrate multiple disciplines, such as electromagnetics, fluid mechanics and so on. The directly driven droplets are mainly composed of ferrofluid or liquid metal. This kind of magnetically induced droplet manipulation provides a remote, wireless and programmable approach beneficial for research and engineering applications, such as drug synthesis, biochemistry, sample preparation in life sciences, biomedicine, tissue engineering, etc. Based on the significant growth in the study of magneto droplet handling achieved over the past decades, further and more profound explorations in this field gained impetus, raising concentrations on the construction of a comprehensive working mechanism and the commercialization of this technology. Current challenges faced are not limited to the design and fabrication of the magnetic field, the material, the acquisition of precise and stable droplet performance, other constraints in processing speed and so on. The rotational devices or systems could give rise to additional issues on bulky appearance, high cost, low reliability, etc. Various magnetically introduced droplet behaviors, such as deformation, displacement, rotation, levitation, splitting and fusion, are mainly introduced in this work, involving the basic theory, functions and working principles.
Topics: Electromagnetic Phenomena; Magnetic Fields; Reproducibility of Results; Tissue Engineering
PubMed: 35323426
DOI: 10.3390/bios12030156 -
Proceedings of the National Academy of... Aug 2023Biological cilia, hairlike organelles on cell surfaces, often exhibit collective wavelike motion known as metachrony, which helps generating fluid flow. Inspired by...
Biological cilia, hairlike organelles on cell surfaces, often exhibit collective wavelike motion known as metachrony, which helps generating fluid flow. Inspired by nature, researchers have developed artificial cilia as microfluidic actuators, exploring several methods to mimic the metachrony. However, reported methods are difficult to miniaturize because they require either control of individual cilia properties or the generation of a complex external magnetic field. We introduce a concept that generates metachronal motion of magnetic artificial cilia (MAC), even though the MAC are all identical, and the applied external magnetic field is uniform. This is achieved by integrating a paramagnetic substructure in the substrate underneath the MAC. Uniquely, we can create both symplectic and antiplectic metachrony by changing the relative positions of MAC and substructure. We demonstrate the flow generation of the two metachronal motions in both high and low Reynolds number conditions. Our research marks a significant milestone by breaking the size limitation barrier in metachronal artificial cilia. This achievement not only showcases the potential of nature-inspired engineering but also opens up a host of exciting opportunities for designing and optimizing microsystems with enhanced fluid manipulation capabilities.
Topics: Cilia; Physical Phenomena; Motion; Cell Membrane; Magnetic Fields
PubMed: 37611057
DOI: 10.1073/pnas.2304519120 -
Journal of Comparative Physiology. A,... Jan 2022Magnetoreception, sensing the Earth's magnetic field, is used by many species in orientation and navigation. While this is established on the behavioural level, there is... (Review)
Review
Magnetoreception, sensing the Earth's magnetic field, is used by many species in orientation and navigation. While this is established on the behavioural level, there is a severe lack in knowledge on the underlying neuronal mechanisms of this sense. A powerful technique to study the neuronal processing of magnetic cues is electrophysiology but, thus far, few studies have adopted this technique. Why is this the case? A fundamental problem is the introduction of electromagnetic noise (induction) caused by the magnetic stimuli, within electrophysiological recordings which, if too large, prevents feasible separation of neuronal signals from the induction artefacts. Here, we address the concerns surrounding the use of electromagnetic coils within electrophysiology experiments and assess whether these would prevent viable electrophysiological recordings within a generated magnetic field. We present calculations of the induced voltages in typical experimental situations and compare them against the neuronal signals measured with different electrophysiological techniques. Finally, we provide guidelines that should help limit and account for possible induction artefacts. In conclusion, if great care is taken, viable electrophysiological recordings from magnetoreceptive cells are achievable and promise to provide new insights on the neuronal basis of the magnetic sense.
Topics: Animals; Electrophysiology; Magnetic Fields; Magnetics; Orientation; Sensation
PubMed: 34713390
DOI: 10.1007/s00359-021-01517-y -
Sensors (Basel, Switzerland) Apr 2021Electromagnetic tracking is a safe, reliable, and cost-effective method to track medical instruments in image-guided surgical navigation. However, patient motion and...
Electromagnetic tracking is a safe, reliable, and cost-effective method to track medical instruments in image-guided surgical navigation. However, patient motion and magnetic field distortions heavily impact the accuracy of tracked position and orientation. The use of redundant magnetic sensors can help to map and mitigate for patient movements and magnetic field distortions within the tracking region. We propose a planar inductive sensor design, printed on PCB and embedded into medical patches. The main advantage is the high repeatability and the cost benefit of using mass PCB manufacturing processes. The article presents new operative formulas for electromagnetic tracking of planar coils on the centimetre scale. The full magnetic analytical model is based on the mutual inductance between coils which can be approximated as being composed by straight conductive filaments. The full model is used to perform accurate system simulations and to assess the accuracy of faster simplified magnetic models, which are necessary to achieve real-time tracking in medical applications.
Topics: Electromagnetic Phenomena; Humans; Magnetic Fields; Surgery, Computer-Assisted
PubMed: 33923811
DOI: 10.3390/s21082822 -
Scientific Reports Jan 2023The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such "spin-sensitive" reactions...
The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such "spin-sensitive" reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions ([Formula: see text]Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions ([Formula: see text]Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80-100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field.
Topics: Magnesium; DNA Replication; Biophysics; Magnetic Fields; Protein Biosynthesis
PubMed: 36627313
DOI: 10.1038/s41598-022-26744-4 -
Theranostics 2022Superparamagnetic nanoparticles have become an important tool in biomedicine. Their biocompatibility, controllable small size, and magnetic properties allow manipulation... (Review)
Review
Superparamagnetic nanoparticles have become an important tool in biomedicine. Their biocompatibility, controllable small size, and magnetic properties allow manipulation with an external magnetic field for a variety of diagnostic and therapeutic applications. Recently, the magnetically-induced motion of superparamagnetic nanoparticles has been investigated as a new source of imaging contrast. In magneto-motive imaging, an external, time-varying magnetic field is applied to move a magnetically labeled subject, such as labeled cells or tissue. Several major imaging modalities such as ultrasound, photoacoustic imaging, optical coherence tomography, and laser speckle tracking can utilize magneto-motive contrast to monitor biological events at smaller scales with enhanced contrast and sensitivity. In this review article, an overview of magneto-motive imaging techniques is presented, including synthesis of superparamagnetic nanoparticles, fundamental principles of magneto-motive force and its utility to excite labeled tissue within a viscoelastic medium, current capabilities of magneto-motive imaging modalities, and a discussion of the challenges and future outlook in the magneto-motive imaging domain.
Topics: Magnetic Fields; Magnetics; Nanoparticles; Tomography, Optical Coherence; Ultrasonography
PubMed: 35198073
DOI: 10.7150/thno.54056 -
Sensors (Basel, Switzerland) Nov 2021The Overhauser magnetometer is a scalar quantum magnetometer based on the dynamic nuclear polarization (DNP) effect in the Earth's magnetic field. Sensitivity is a key...
The Overhauser magnetometer is a scalar quantum magnetometer based on the dynamic nuclear polarization (DNP) effect in the Earth's magnetic field. Sensitivity is a key technical specification reflecting the ability of instruments to sense small variations of the Earth's magnetic field and is closely related to the signal-to-noise ratio (SNR) of the free induction decay (FID) signal. In this study, deuterated N TEMPONE radical is used in our sensor to obtain high DNP enhancement. The measured SNR of the FID signal is approximately 63/1, and the transverse relaxation time is 2.68 s. The direct measurement method with a single instrument and the synchronous measurement method with two instruments are discussed for sensitivity estimation in time and frequency domains under different electromagnetic interference (EMI) environments and different time periods. For the first time, the correlation coefficient of the magnetic field measured by the two instruments is used to judge the degree of the influence of the environmental noise on the sensitivity estimation. The sensitivity evaluation in the field environment is successfully realized without electrical and magnetic shields. The direct measurement method is susceptible to EMI and cannot work in general electromagnetic environments, except it is sufficiently quiet. The synchronous measurement method has an excellent ability to remove most natural and artificial EMIs and can be used under noisy environments. Direct and synchronous experimental results show that the estimated sensitivity of the JOM-4S magnetometer is approximately 0.01 nT in time domain and approximately 0.01 nT/Hz in frequency domain at a 3 s cycling time. This study provides a low-cost, simple, and effective sensitivity estimation method, which is especially suitable for developers and users to estimate the performance of the instrument.
Topics: Electricity; Magnetic Fields; Magnetics; Signal-To-Noise Ratio
PubMed: 34833789
DOI: 10.3390/s21227698 -
Ultrasonics Sonochemistry Aug 2021Ultrasound has the potential to be broadly applied in the field of agricultural food processing due to advantages such as environmental friendliness, low energy costs,... (Review)
Review
Ultrasound has the potential to be broadly applied in the field of agricultural food processing due to advantages such as environmental friendliness, low energy costs, no need for exogenous additives and ease of operation. High-frequency ultrasound is mainly used in medical diagnosis and in the food industry for the identification of ingredients and production line quality testing, while low-frequency ultrasounds is mainly used for extraction and separation, accelerating chemical reactions, auxiliary microbial fermentation and quality enhancement in food industry. Magnetic fields have many advantages of convenient use, such as non-toxic, nonpolluting and safe. High-intensity pulsed magnetic fields are widely used as a physical non-thermal sterilization technology in food processing, while weak magnetic fields are better at activating microorganisms and promoting their growth. Ultrasound and magnetic fields, due to their positive biological effects, have a wide range of applications in the food processing industry. This paper provides an overview of the research progress and applications of ultrasound and magnetic fields in food processing from the perspectives of their biological effects and mechanisms of action. Additionally, with the development and application of physical field technology, physical fields can now be used to provide significant technical advantages for assisting fermentation. Suitable physical fields can promote the growth of microbial cells, improve mycelial production and increase metabolic activity. Furthermore, the current status of research into the use of ultrasound and magnetic field technologies for assisting the fermentation of rare edible fungi, is discussed.
Topics: Fermentation; Food Handling; Food Industry; Fungi; Magnetic Fields; Ultrasonic Waves
PubMed: 34119905
DOI: 10.1016/j.ultsonch.2021.105613