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ASAIO Journal (American Society For... May 2022Cleveland Clinic's continuous-flow total artificial heart (CFTAH) is a double-ended centrifugal blood pump that has a single rotating assembly with an embedded magnet,...
Cleveland Clinic's continuous-flow total artificial heart (CFTAH) is a double-ended centrifugal blood pump that has a single rotating assembly with an embedded magnet, which is axially and radially suspended by a balance of magnetic and hydrodynamic forces. The key to the radial suspension is a radial offset between the stator bearing bore and the magnet's steel laminations. This offset applies a radial magnetic force, which is balanced by a hydrodynamic force as the rotating assembly moves to a "force-balanced" radial position. The journal-bearing blood passage is a narrow flow path between the left and right impellers. The intent of this study was to determine the impact of the stator-bearing bore radius on the journal-bearing hydraulic performance while satisfying the geometric design constraints imposed by the pump and motor configuration. Electromagnetic forces on the journal bearing were calculated using the ANSYS EMAG program, Version 18 (ANSYS, Canonsburg, PA). ANSYS CFX Version 19.2 was then used to model the journal-bearing flow paths of the most recent design of the CFTAH. A transient, moving mesh approach was used to locate the steady state, force-balanced position of the rotating assembly. The blood was modeled as a non-Newtonian fluid. The computational fluid dynamics simulations showed that by increasing stator bore radius, rotor power, stator wall average shear stress, and blood residence time in journal-bearing decrease, while blood net flow rate through the bearing increases. The results were used to select a new bearing design that provides an improved performance compared with the baseline design. The performance of the new CFTAH-bearing design will be confirmed through upcoming in vitro and in vivo testing.
Topics: Equipment Design; Heart, Artificial; Heart-Assist Devices; Hydrodynamics; Magnetics
PubMed: 34380949
DOI: 10.1097/MAT.0000000000001556 -
Journal of Magnetic Resonance (San... Nov 2018The dynamics of spin system coupled by chemical exchange between two sites with different chemical shifts during periodic radiofrequency (RF) irradiation was here...
The dynamics of spin system coupled by chemical exchange between two sites with different chemical shifts during periodic radiofrequency (RF) irradiation was here investigated. When the instantaneous π-flip of effective frequency during the course of frequency sweep was applied, a significant increase of exchange-induced relaxation rate constants was observed for small tip angle of magnetization in the laboratory frame of reference. This increase of the rate constants corresponds to the side bands generated by the periodic irradiation during the RF pulses. The exchange - induced relaxation rate constants depend on the exchange conditions, the RF power and the irradiation period. The described phenomenon promises applications for studying protein dynamics and for generating exchange specific relaxation contrasts in MRI.
Topics: Algorithms; Computer Simulation; Image Interpretation, Computer-Assisted; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Magnets; Radio Waves
PubMed: 30223154
DOI: 10.1016/j.jmr.2018.09.001 -
JAMA Dermatology Oct 2018Cardiovascular implanted electronic devices (CIEDs) are susceptible to electromagnetic interference. Dermatologists regularly use devices containing magnets, including... (Observational Study)
Observational Study
IMPORTANCE
Cardiovascular implanted electronic devices (CIEDs) are susceptible to electromagnetic interference. Dermatologists regularly use devices containing magnets, including dermatoscopes and their attachments, which could pose a hazard to patients with CIEDs.
OBJECTIVE
To investigate the safety risk of magnets in dermatoscopes to patients with CIEDs.
DESIGN, SETTING, AND PARTICIPANTS
This cross-sectional observational study was conducted between January 1, 2018, and March 31, 2018, in a controlled laboratory setting. Two experiments were performed. In the first experiment (performed in the Dermatology Service at Memorial Sloan Kettering Cancer Center, New York), dermatoscopes that contain magnets were obtained from 3 manufacturers. Using a magnometer, the magnetic field strength of the dermatoscopes was measured over the magnet; at the faceplate; and at a distance of 0.5 cm, 1 cm and 15 cm away from the faceplate. In the second experiment (performed in the University Heart Center Zurich, Zurich, Switzerland), ex vivo measurements were conducted to determine how the dermatoscopes affected old-generation and new generation CIEDs (pacemakers and implantable defibrillators).
MAIN OUTCOMES AND MEASURES
Magnetic field strength as measured directly over the dermatoscope magnet; at the faceplate; and at distances of 0.5 cm, 1 cm, and 15 cm from the faceplate. Pacemaker and defibrillator operation when exposed to dermatoscopes.
RESULTS
After conducting 24 measurements, the magnetic field (measured in gauss [G]) strength varied between 24.26 G and 163.04 G over the dermatoscope magnet, between 2.22 G and 9.98 G at the dermatoscope faceplate, between 0.82 G and 2.4 G at a distance of 0.5 cm, and between 0.5 G and 1.04 G at a distance of 1 cm; it was 0 for all devices at a 15 cm distance. The field strength at the faceplate was found to be generally below the CIED industry standard safety threshold. None of the dermatoscopes in the ex vivo experiment exerted any demonstrable disruptions or changes to the CIEDs.
CONCLUSIONS AND RELEVANCE
In real life, dermatoscope magnets likely present no measurable safety risk to patients with CIEDs. Using the polarized noncontact mode permits dermoscopy to be performed at least 0.5 cm from the skin surface, where the magnetic field strength was well below the 5-G safety threshold.
Topics: Cross-Sectional Studies; Defibrillators, Implantable; Dermoscopy; Electromagnetic Fields; Magnets; Pacemaker, Artificial; Risk Assessment; Safety
PubMed: 30140894
DOI: 10.1001/jamadermatol.2018.2531 -
Nano Letters Oct 2019Magnetogenetics is a new field that leverages genetically encoded proteins and protein assemblies that are sensitive to magnetic fields to study and manipulate cell...
Magnetogenetics is a new field that leverages genetically encoded proteins and protein assemblies that are sensitive to magnetic fields to study and manipulate cell behavior. Theoretical studies show that many proposed magnetogenetic proteins do not contain enough iron to generate substantial magnetic forces. Here, we have engineered a genetically encoded ferritin-containing protein crystal that grows inside mammalian cells. Each of these crystals contains more than 10 million ferritin subunits and is capable of mineralizing substantial amounts of iron. When isolated from cells and loaded with iron , these crystals generate magnetic forces that are 9 orders of magnitude larger than the forces from the single ferritin cages used in previous studies. These protein crystals are attracted to an applied magnetic field and move toward magnets even when internalized into cells. While additional studies are needed to realize the full potential of magnetogenetics, these results demonstrate the feasibility of engineering protein assemblies for magnetic sensing.
Topics: Animals; Crystallization; Ferritins; HEK293 Cells; Humans; Iron; Magnetic Fields; Magnets; Mice; Protein Engineering; RAW 264.7 Cells
PubMed: 31552740
DOI: 10.1021/acs.nanolett.9b02266 -
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi =... Oct 2023The portable light-weight magnetic resonance imaging system can be deployed in special occasions such as Intensive Care Unit (ICU) and ambulances, making it possible to...
The portable light-weight magnetic resonance imaging system can be deployed in special occasions such as Intensive Care Unit (ICU) and ambulances, making it possible to implement bedside monitoring imaging systems, mobile stroke units and magnetic resonance platforms in remote areas. Compared with medium and high field imaging systems, ultra-low-field magnetic resonance imaging equipment utilizes light-weight permanent magnets, which are compact and easy to move. However, the image quality is highly susceptible to external electromagnetic interference without a shielded room and there are still many key technical problems in hardware design to be solved. In this paper, the system hardware design and environmental electromagnetic interference elimination algorithm were studied. Consequently, some research results were obtained and a prototype of portable shielding-free 50 mT magnetic resonance imaging system was built. The light-weight magnet and its uniformity, coil system and noise elimination algorithm and human brain imaging were verified. Finally, high-quality images of the healthy human brain were obtained. The results of this study would provide reference for the development and application of ultra-low-field magnetic resonance imaging technology.
Topics: Humans; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Head; Equipment Design; Magnets
PubMed: 37879910
DOI: 10.7507/1001-5515.202303060 -
Nature Communications Jul 2023The search for new elementary particles is one of the most basic pursuits in physics, spanning from subatomic physics to quantum materials. Magnons are the ubiquitous...
The search for new elementary particles is one of the most basic pursuits in physics, spanning from subatomic physics to quantum materials. Magnons are the ubiquitous elementary quasiparticle to describe the excitations of fully-ordered magnetic systems. But other possibilities exist, including fractional and multipolar excitations. Here, we demonstrate that strong quantum interactions exist between three flavors of elementary quasiparticles in the uniaxial spin-one magnet FeI. Using neutron scattering in an applied magnetic field, we observe spontaneous decay between conventional and heavy magnons and the recombination of these quasiparticles into a super-heavy bound-state. Akin to other contemporary problems in quantum materials, the microscopic origin for unusual physics in FeI is the quasi-flat nature of excitation bands and the presence of Kitaev anisotropic magnetic exchange interactions.
Topics: Magnets; Anisotropy; Magnetic Fields; Neutrons; Physics
PubMed: 37452016
DOI: 10.1038/s41467-023-39940-1 -
Biophysical Journal Feb 2021Mechanobiology is focused on how the physical forces and mechanical properties of proteins, cells, and tissues contribute to physiology and disease. Although the...
Mechanobiology is focused on how the physical forces and mechanical properties of proteins, cells, and tissues contribute to physiology and disease. Although the response of proteins and cells to mechanical stimuli is critical for function, the tools to probe these activities are typically restricted to single-molecule manipulations. Here, we have developed a novel microplate reader assay to encompass mechanical measurements with ensemble biochemical and cellular assays, using a microplate lid modified with magnets. This configuration enables multiple static magnetic tweezers to function simultaneously across the microplate, thereby greatly increasing throughput. We demonstrate the broad applicability and versatility through in vitro and in cellulo approaches. Overall, our methodology allows, for the first time (to our knowledge), ensemble biochemical and cell-based assays to be performed under force in high-throughput format. This approach substantially increases the availability of mechanobiology measurements.
Topics: Biophysics; Magnetics; Magnets; Mechanical Phenomena; Nanotechnology
PubMed: 33453266
DOI: 10.1016/j.bpj.2020.12.024 -
Revista de Gastroenterologia de Mexico... 2022The ingestion of foreign bodies, such as magnets, is a potentially lethal accident that affects children and is associated with bleeding and gastrointestinal...
INTRODUCTION AND AIMS
The ingestion of foreign bodies, such as magnets, is a potentially lethal accident that affects children and is associated with bleeding and gastrointestinal perforation, as well as death. There are no Latin American reports in the literature on cases of magnet ingestion in children. Our aim was to establish whether said ingestion has been seen by pediatric endoscopists and gastroenterologists in Latin America, to determine the scope of that potential threat in their patient populations.
MATERIALS AND METHODS
We collected data regarding endoscopies performed on children in Latin America, within the time frame of 2017-2019, through questionnaires that were distributed to pediatric endoscopists at the 2nd World Congress of Gastrointestinal Endoscopy (ENDO 2020). The questionnaires provided information on foreign body location, the presence and number of ingested magnets, and the description of complications and surgical interventions.
RESULTS
Our cohort from 12 Latin American countries reported 2,363 endoscopies due to foreign body ingestion, 25 (1.05%) of which were the result of having swallowed one or more magnets. Mean patient age was 5.14 years (SD 2.5) and 10 (40%) of the cases were girls. Three (12%) of the patients presented with severe complications and 2 (8%) cases required surgery.
CONCLUSIONS
Our preliminary study suggests that the ingestion of magnets is not common in Latin American countries, but said cases are frequently associated with complications. Constant monitoring of the incidence of such cases is extremely important, so that through education and awareness of those events, life-threatening complications in children can be prevented.
Topics: Child; Child, Preschool; Eating; Endoscopy, Gastrointestinal; Female; Foreign Bodies; Humans; Incidence; Magnets; Male; United States
PubMed: 34794926
DOI: 10.1016/j.rgmxen.2021.01.002 -
The Journal of Physical Chemistry. B Mar 2023The adsorption of oxidatively damaged DNA onto ferromagnetic substrates was investigated. Both confocal fluorescence microscopy and quartz crystal microbalance methods...
The adsorption of oxidatively damaged DNA onto ferromagnetic substrates was investigated. Both confocal fluorescence microscopy and quartz crystal microbalance methods show that the adsorption rate and the coverage depend on the magnetization direction of the substrate and the position of the damage site on the DNA relative to the substrate. SQUID magnetometry measurements show that the subsequent magnetic susceptibility of the DNA-coated ferromagnetic film depends on the direction of the magnetic field that was applied to the ferromagnetic film as the molecules were adsorbed. This study reveals that (i) the spin and charge polarization in DNA molecules is changed significantly by oxidative damage in the G bases and (ii) the rate of adsorption on a ferromagnet, as a function of the direction of the magnetic dipole of the surface, can be used as an assay to detect oxidative damage in the DNA.
Topics: Adsorption; Magnets; DNA; Microscopy, Fluorescence; Quartz Crystal Microbalance Techniques
PubMed: 36888909
DOI: 10.1021/acs.jpcb.2c08820 -
Molecules (Basel, Switzerland) Mar 2022Biomolecules participate in various physiological and pathological processes through intermolecular interactions generally driven by non-covalent forces. In the present... (Review)
Review
Biomolecules participate in various physiological and pathological processes through intermolecular interactions generally driven by non-covalent forces. In the present review, the force-induced remnant magnetization spectroscopy (FIRMS) is described and illustrated as a novel method to measure non-covalent forces. During the FIRMS measurement, the molecular magnetic probes are magnetized to produce an overall magnetization signal. The dissociation under the interference of external force yields a decrease in the magnetic signal, which is recorded and collected by atomic magnetometer in a spectrum to study the biological interactions. Furthermore, the recent FIRMS development with various external mechanical forces and magnetic probes is summarized.
Topics: Magnetics; Mechanical Phenomena; Microscopy, Atomic Force; Molecular Probes; Spectrum Analysis
PubMed: 35408471
DOI: 10.3390/molecules27072072