Going Hands-Free: MagnetoSuture™ for Untethered Guided Needle Penetration of Human Tissue Ex Vivo

The application of force in surgical settings is typically accomplished via physical tethers to the surgical tool. While physical tethers are common and critical, some internal surgical procedures may benefit from a tetherless operation of needles, possibly reducing the number of ports in the patient or the amount of tissue damage caused by tools used to manipulate needles. Magnetic field gradients can dynamically apply kinetic forces to magnetizable objects free of such tethers, possibly enabling ultra-minimally invasive robotic surgical procedures. We demonstrate the untethered manipulation of a suture needle in vitro, exemplified by steering through narrow holes, as well as needle penetration through excised rat and human tissues. We present proof of principle manipulations for the fully untethered control of a minimally modified, standard stainless steel surgical suture needle.

Power Frequency Еlectromagnetic Fields of Electrical Installations in Buildings

Introduction: All components of the power supply system are sources of electric and magnetic fields of industrial frequency of 50 Hz, both posing risks to human health. Estimation of predicted magnetic field levels from switchboards and transformers inside buildings is challenging and implies the importance of full-scale measurements of electromagnetic fields from built-in electrical equipment. Objectives: To establish the levels of 50 Hz electromagnetic fields during operation of built-in electrical installations in industrial, public, and residential premises. Materials and methods: We studied 50 Hz electromagnetic fields generated by electrical installations located in buildings. EMF levels were measured near transformers, switchboards, and switchgear. The electromagnetic situation in the rooms above the electrical equipment was investigated. The assessment of EMF levels was carried out in accordance with the current hygienic standards. Results: The intensity of electric fields near the equipment and in the surveyed premises was significantly lower than that of magnetic fields. The excess of maximum permissible levels at workplaces of operators servicing EMF sources in residential buildings was not detected. In the rooms of public buildings located above electrical installations, measured values of magnetic field induction ranged from 0.18 to 31 µT. The intensity of magnetic fields depended on the current load and the distance from EMF sources. Discussion: Electromagnetic field intensity depends on specifications of equipment, current loads, and distances from the sources of electromagnetic fields. Induction of 50 Hz magnetic fields in adjacent rooms may exceed hygienic standards set for residential and public buildings. Additional adverse factors include instability of magnetic fields caused by current load changes and significant magnetic field gradients in premises.

METHOD OF CALCULATION OF MAGNETIC SEPARATORS WITH A FERROMAGNETIC BALL NOZZLE FOR CLEANING SUSPENSIONS FROM MAGNETIC IMPURITIES

Для повышения эффекта очистки суспензий от магнитных частиц экономически целесообразно в промышленных условиях использовать устройства с магнитными полями невысокой напряженности, но имеющими высокие градиенты магнитного поля в рабочем пространстве. В качестве таких устройств используются магнитные сепараторы с ферромагнитной шаровой насадкой. Для расчетов за основу взята модель процесса осаждения магнитных частиц в квазисплошном поглощающем экране магнитного фильтра, при этом предполагается, что рельеф зоны захвата в окрестности точек контакта намагниченных шаров будет в виде сегментов с характерными размерами rо и b. Анализ такой модели позволил отметить подобие рассмотренных процессов осаждения в магнитном сепараторе процессам адсорбции и в дальнейшем использовать элементы теории процесса адсорбции для расчетов таких сепараторов. Представлена методика расчета магнитных сепараторов с ферромагнитной шаровой насадкой для очистки суспензий от магнитных примесей. Экспериментальная проверка расчетных зависимостей при очистке антифрикционной присадки «Деста» подтвердила возможность использования предложенной методики для магнитных сепараторов с ферромагнитной шаровой насадкой To increase the effect of cleaning suspensions from magnetic particles, it is economically feasible in industrial conditions to use devices with low-intensity magnetic fields, but having high magnetic field gradients in the working space. As such devices, magnetic separators with a ferromagnetic ball nozzle are used. The calculations are based on a model of deposition of magnetic particles in a magnetic absorbing screen, and it is assumed that the topography of the capture zone in the vicinity of the contact points of the magnetized balls will have the form of segments with characteristic sizes ro and b. The analysis of such a model allowed us to note the similarity of the considered deposition processes in the magnetic separator with the adsorption processes and to further use the elements of the theory of the adsorption process for the calculations of such separators. A method for calculating magnetic separators with a ferromagnetic ball nozzle for cleaning suspensions from magnetic impurities is presented. Experimental verification of the calculated dependences during the cleaning of the anti-friction additive "Desta" confirmed the possibility of using the proposed calculation method for magnetic separators with a ferromagnetic ball nozzle.

Assessment of the Exposure to Gradient Magnetic Fields Generated by MRI Tomographs: Measurement Method, Verification of Limits and Clearance Areas through a Web-Based Platform

This work is the result of a campaign of measures of exposure levels to magnetic field gradients (GMF) generated by magnetic resonance imaging (MRI) tomographs, to which both healthcare staff and any persons accompanying patients who remain inside the magnet room are exposed while performing a diagnostic Investigation. The study was conducted on three MRI tomographs with a static magnetic induction field up to 1.5 T installed in two hospitals of Lombardy. The study aims to characterize electromagnetic emissions within the magnet room and the definition of a measurement method suitable for assessing the level of exposure of healthcare personnel and any persons accompanying patients. The measurements performed concerned the determination of the weighted peak index for magnetic induction, due to the diagnostic GMF, relating to the action levels for the workers and the reference levels for the general population, in force in the European Union. Thanks to the defined experimental setup, the use of two different measuring instruments, and the software resources of the WEBNIR platform, it was possible to identify, for both categories of exposed persons, the “clearance” space, i.e., the distance from the magnet of the tomograph that guarantees health protection concerning the exposure to GMF, according to the indications of the standards in force. The method used showed that the exposure levels to GMF are substantially safe for professionally exposed workers who do not carry specific risks. For workers particularly sensitive to the specific risk, as well as to individuals part of the population, it is however advisable to maintain a distance from the magnet of about one meter to prevent sensorial neuromuscular stimulation effects.

Solar wind speed and rotational shear at coronal hole boundaries, impacts on magnetic field inversions

<p>The solar wind is frequently perturbed by transient structures such as magnetic folds, jets, waves and flux-ropes that propagate rapidly away from the Sun over a large range of heliocentric distances. Parker Solar Probe has revealed that rotations of the magnetic field vector occur repeatedly at small heliocentric distances, on regions that also display surprisingly large solar wind rotation rates. Sun-to-spacecraft connectivity analysis shows that a large fraction of the solar wind flows probed so far by Parker Solar Probe were formed and accelerated in the vicinity of coronal hole boundaries.<br>We show by means of of global MHD simulations that coronal rotation is highly structured in proximity to those boundary regions (in agreement with preceding SoHO/UVCS observations), and that enhanced poloidal and toroidal flow shear and magnetic field gradients also develop there. We identified regions of the solar corona for which solar wind speed and rotational shear are significant, that can be associated with field-aligned and/or transverse vorticity, and that can be favourable to the development of magnetic deflections. Some of these wind flow shears are driven through large radial extensions, being noticeable tens of solar radii away from the surface, and therefore have a potential impact on the propagation of such magnetic perturbations across extended heights in the solar wind. We conclude that these regions of persistent shears are undoubtedly sources of complex solar wind structures, and suggest that they can trigger instabilities capable of creating magnetic field reversals detected in-situ in the heliosphere.<br>Our simulations furthermore indicate that the spatial structure of the solar wind shear will become more complex as the solar cycle progresses, with strong and extended shears appearing at heliographic latitudes that will be probed by Solar Orbiter in the near future.</p>

Simulated basis sets for semi-LASER: the impact of including shaped RF pulses and magnetic field gradients

Objective To study the need for inclusion of shaped RF pulses and magnetic field gradients in simulations of basis sets for the analysis of proton MR spectra of single voxels of the brain acquired with a semi-LASER pulse sequence. Materials and methods MRS basis sets where simulated at different echo times with hard RF pulses as well as with shaped RF pulses without or with magnetic field gradients included. The influence on metabolite concentration quantification was assessed using both phantom and in vivo measurements. For comparison, simulations and measurements were performed with the PRESS pulse sequence. Results The effect of including gradients in the simulations was smaller for semi-LASER than for PRESS, however, still noticeable. The difference was larger for strongly coupled metabolites and at longer echo times. Metabolite quantification using semi-LASER was thereby less dependent on the inclusion of gradients than PRESS, which was seen in both phantom and in vivo measurements. Discussion The inclusion of the shaped RF pulses and magnetic field gradients in the simulation of basis sets for semi-LASER is only important for strongly coupled metabolites. If computational time is a limiting factor, simple simulations with hard RF pulses can provide almost as accurate metabolite quantification as those that include the chemical-shift related displacement.

Longitudinal and transverse electron paramagnetic resonance in a scanning tunneling microscope

Electron paramagnetic resonance (EPR) spectroscopy is widely used to characterize paramagnetic complexes. Recently, EPR combined with scanning tunneling microscopy (STM) achieved single-spin sensitivity with sub-angstrom spatial resolution. The excitation mechanism of EPR in STM, however, is broadly debated, raising concerns about widespread application of this technique. We present an extensive experimental study and modeling of EPR-STM of Fe and hydrogenated Ti atoms on a MgO surface. Our results support a piezoelectric coupling mechanism, in which the EPR species oscillate adiabatically in the inhomogeneous magnetic field of the STM tip. An analysis based on Bloch equations combined with atomic-multiplet calculations identifies different EPR driving forces. Specifically, transverse magnetic field gradients drive the spin-1/2 hydrogenated Ti, whereas longitudinal magnetic field gradients drive the spin-2 Fe. Also, our results highlight the potential of piezoelectric coupling to induce electric dipole moments, thereby broadening the scope of EPR-STM to nonpolar species and nonlinear excitation schemes.