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Journal of the Royal Society, Interface Sep 2019Birds can use two kinds of information from the geomagnetic field for navigation: the direction of the field lines as a compass and probably magnetic intensity as a... (Review)
Review
Birds can use two kinds of information from the geomagnetic field for navigation: the direction of the field lines as a compass and probably magnetic intensity as a component of the navigational 'map'. The direction of the magnetic field appears to be sensed via radical pair processes in the eyes, with the crucial radical pairs formed by cryptochrome. It is transmitted by the optic nerve to the brain, where parts of the visual system seem to process the respective information. Magnetic intensity appears to be perceived by magnetite-based receptors in the beak region; the information is transmitted by the ophthalmic branch of the trigeminal nerve to the trigeminal ganglion and the trigeminal brainstem nuclei. Yet in spite of considerable progress in recent years, many details are still unclear, among them details of the radical pair processes and their transformation into a nervous signal, the precise location of the magnetite-based receptors and the centres in the brain where magnetic information is combined with other navigational information for the navigational processes.
Topics: Animal Migration; Animals; Birds; Cryptochromes; Magnetic Fields; Orientation; Perception
PubMed: 31480921
DOI: 10.1098/rsif.2019.0295 -
Journal of Magnetic Resonance Imaging :... Feb 2021Magnetic resonance imaging and spectroscopy (MRI/MRS) at 7T represents an exciting advance in MR technology, with intriguing possibilities to enhance image spatial,...
Magnetic resonance imaging and spectroscopy (MRI/MRS) at 7T represents an exciting advance in MR technology, with intriguing possibilities to enhance image spatial, spectral, and contrast resolution. To ensure the safe use of this technology while still harnessing its potential, clinical staff and researchers need to be cognizant of some safety concerns arising from the increased magnetic field strength and higher Larmor frequency. The higher static magnetic fields give rise to enhanced transient bioeffects and an increased risk of adverse incidents related to electrically conductive implants. Many technical challenges remain and the continuing rapid pace of development of 7T MRI/MRS is likely to present further challenges to ensuring safety of this technology in the years ahead. The recent regulatory clearance for clinical diagnostic imaging at 7T will likely increase the installed base of 7T systems, particularly in hospital environments with little prior ultrahigh-field MR experience. Informed risk/benefit analyses will be required, particularly where implant manufacturer-published 7T safety guidelines for implants are unavailable. On behalf of the International Society for Magnetic Resonance in Medicine, the aim of this article is to provide a reference document to assist institutions developing local institutional policies and procedures that are specific to the safe operation of 7T MRI/MRS. Details of current 7T technology and the physics underpinning its functionality are reviewed, with the aim of supporting efforts to expand the use of 7T MRI/MRS in both research and clinical environments. Current gaps in knowledge are also identified, where additional research and development are required. Level of Evidence 5 Technical Efficacy 2 J. MAGN. RESON. IMAGING 2021;53:333-346.
Topics: Humans; Magnetic Fields; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Physics
PubMed: 32830900
DOI: 10.1002/jmri.27319 -
Sensors (Basel, Switzerland) Apr 2023Biomagnetism is the measurement of the weak magnetic fields produced by nerves and muscle. The magnetic field of the heart-the magnetocardiogram (MCG)-is the largest... (Review)
Review
Biomagnetism is the measurement of the weak magnetic fields produced by nerves and muscle. The magnetic field of the heart-the magnetocardiogram (MCG)-is the largest biomagnetic signal generated by the body and was the first measured. Magnetic fields have been detected from isolated tissue, such as a peripheral nerve or cardiac muscle, and these studies have provided insights into the fundamental properties of biomagnetism. The magnetic field of the brain-the magnetoencephalogram (MEG)-has generated much interest and has potential clinical applications to epilepsy, migraine, and psychiatric disorders. The biomagnetic inverse problem, calculating the electrical sources inside the brain from magnetic field recordings made outside the head, is difficult, but several techniques have been introduced to solve it. Traditionally, biomagnetic fields are recorded using superconducting quantum interference device (SQUID) magnetometers, but recently, new sensors have been developed that allow magnetic measurements without the cryogenic technology required for SQUIDs.
Topics: Humans; Heart; Magnetoencephalography; Brain; Magnetic Fields; Myocardium
PubMed: 37177427
DOI: 10.3390/s23094218 -
International Journal of Molecular... May 2023This short review reports the surprising phenomenon of nuclear hyperpolarization occurring in chemical reactions, which is called CIDNP (chemically induced dynamic... (Review)
Review
This short review reports the surprising phenomenon of nuclear hyperpolarization occurring in chemical reactions, which is called CIDNP (chemically induced dynamic nuclear polarization) or photo-CIDNP if the chemical reaction is light-driven. The phenomenon occurs in both liquid and solid-state, and electron transfer systems, often carrying flavins as electron acceptors, are involved. Here, we explain the physical and chemical properties of flavins, their occurrence in spin-correlated radical pairs (SCRP) and the possible involvement of flavin-carrying SCRPs in animal magneto-reception at earth's magnetic field.
Topics: Animals; Flavoproteins; Magnetic Fields; Electron Transport; Flavins
PubMed: 37175925
DOI: 10.3390/ijms24098218 -
Journal of Comparative Physiology. A,... Jan 2022In addition to providing animals with a source of directional or 'compass' information, Earth's magnetic field also provides a potential source of positional or 'map'... (Review)
Review
In addition to providing animals with a source of directional or 'compass' information, Earth's magnetic field also provides a potential source of positional or 'map' information that animals might exploit to assess location. In less than a generation, the idea that animals use Earth's magnetic field as a kind of map has gone from a contentious hypothesis to a well-established tenet of animal navigation. Diverse animals ranging from lobsters to birds are now known to use magnetic positional information for a variety of purposes, including staying on track along migratory pathways, adjusting food intake at appropriate points in a migration, remaining within a suitable oceanic region, and navigating toward specific goals. Recent findings also indicate that sea turtles, salmon, and at least some birds imprint on the magnetic field of their natal area when young and use this information to facilitate return as adults, a process that may underlie long-distance natal homing (a.k.a. natal philopatry) in many species. Despite recent progress, much remains to be learned about the organization of magnetic maps, how they develop, and how animals use them in navigation.
Topics: Animal Migration; Animals; Birds; Magnetic Fields; Magnetics; Turtles
PubMed: 34999936
DOI: 10.1007/s00359-021-01529-8 -
Theranostics 2021The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment.... (Review)
Review
The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment. Combinations of multiple modalities provide numerous medical advantages and are enabled by nano- and micron-sized mediators. Here we review recent advancements in the field of ultrasound theranostics and the use of magnetic materials as mediators. Several subdisciplines are described in detail, including controlled drug delivery and release, ultrasound hyperthermia, magneto-ultrasonic heating, sonodynamic therapy, magnetoacoustic imaging, ultrasonic wave generation by magnetic fields, and ultrasound tomography. The continuous progress and improvement in theranostic materials, methods, and physical computing models have created undeniable possibilities for the development of new approaches. We discuss the prospects of ultrasound theranostics and possible expansions of other studies to the theranostic context.
Topics: Animals; Drug Delivery Systems; Humans; Magnetic Field Therapy; Magnetic Fields; Magnetics; Nanoparticles; Neoplasms; Precision Medicine; Theranostic Nanomedicine; Ultrasonic Therapy; Ultrasonic Waves; Ultrasonography
PubMed: 34815806
DOI: 10.7150/thno.62218 -
Molecules (Basel, Switzerland) Jun 2022Magnetic composites and self-healing materials have been drawing much attention in their respective fields of application. Magnetic fillers enable changes in the... (Review)
Review
Magnetic composites and self-healing materials have been drawing much attention in their respective fields of application. Magnetic fillers enable changes in the material properties of objects, in the shapes and structures of objects, and ultimately in the motion and actuation of objects in response to the application of an external field. Self-healing materials possess the ability to repair incurred damage and consequently recover the functional properties during healing. The combination of these two unique features results in important advances in both fields. First, the self-healing ability enables the recovery of the magnetic properties of magnetic composites and structures to extend their service lifetimes in applications such as robotics and biomedicine. Second, magnetic (nano)particles offer many opportunities to improve the healing performance of the resulting self-healing magnetic composites. Magnetic fillers are used for the remote activation of thermal healing through inductive heating and for the closure of large damage by applying an alternating or constant external magnetic field, respectively. Furthermore, hard magnetic particles can be used to permanently magnetize self-healing composites to autonomously re-join severed parts. This paper reviews the synthesis, processing and manufacturing of magnetic self-healing composites for applications in health, robotic actuation, flexible electronics, and many more.
Topics: Magnetic Fields; Magnetics; Robotics
PubMed: 35744920
DOI: 10.3390/molecules27123796 -
Acta Otorhinolaryngologica Italica :... Oct 2023
Topics: Humans; Nystagmus, Pathologic; Vertigo; Magnetic Fields
PubMed: 37519140
DOI: 10.14639/0392-100X-N2485 -
Annual Review of Neuroscience Jul 2019Magnetic fields pass through tissue undiminished and without producing harmful effects, motivating their use as a wireless, minimally invasive means to control neural... (Review)
Review
Magnetic fields pass through tissue undiminished and without producing harmful effects, motivating their use as a wireless, minimally invasive means to control neural activity. Here, we review mechanisms and techniques coupling magnetic fields to changes in electrochemical potentials across neuronal membranes. Biological magnetoreception, although incompletely understood, is discussed as a potential source of inspiration. The emergence of magnetic properties in materials is reviewed to clarify the distinction between biomolecules containing transition metals and ferrite nanoparticles that exhibit significant net moments. We describe recent developments in the use of magnetic nanomaterials as transducers converting magnetic stimuli to forms readily perceived by neurons and discuss opportunities for multiplexed and bidirectional control as well as the challenges posed by delivery to the brain. The variety of magnetic field conditions and mechanisms by which they can be coupled to neuronal signaling cascades highlights the desirability of continued interchange between magnetism physics and neurobiology.
Topics: Animals; Anxiety; Behavior, Animal; Brain; Humans; Magnetic Fields; Nerve Net; Neurons
PubMed: 30939100
DOI: 10.1146/annurev-neuro-070918-050241 -
Sensors (Basel, Switzerland) Sep 2020Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in... (Review)
Review
Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in size, and have low hysteresis and power consumption. However, the performance of these biosensors is influenced by a variety of factors, including the design, geometry, materials and fabrication procedures. Other less appreciated factors influencing the MI effect include measuring circuit implementation, the material used for construction, geometry of the thin film sensing element, and patterning shapes compatible with the interface microelectronic circuitry. The type magnetic (ferrofluid, Dynabeads, and nanoparticles) and size of the particles, the magnetic particle concentration, magnetic field strength and stray magnetic fields can also affect the sensor sensitivity. Based on these considerations it is proposed that ideal MI biosensor sensitivity could be achieved when the sensor is constructed in sandwich thick magnetic layers with large sensing area in a meander shape, measured with circuitry that provides the lowest possible external inductance at high frequencies, enclosed by a protective layer between magnetic particles and sensing element, and perpendicularly magnetized when detecting high-concentration of magnetic particles.
Topics: Biosensing Techniques; Electric Impedance; Magnetic Fields; Magnetics; Nanoparticles
PubMed: 32932740
DOI: 10.3390/s20185213