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The investigation addresses the magnetostrictive sensor (MsS) signal received from pipes of different materials using an amorphous alloy as a sensor element. This sensing system also acts as a transducer to generate ultrasonic waves which appear as echoes from pipe end and defect. The static magnetic field revealed different MsS signals from magnetically different pipes, viz., aluminum (nonmagnetic), galvanized iron (nonmagnetic coating), and mild steel (magnetic) pipes. Applied static field enhanced MsS signals in all the pipes. The extent of this enhancement is influenced by transduction efficiency of the MsS transducer. This efficiency varied with the magnetic nature of the pipe. Simulation through COMSOL Multiphysics elucidated the magnetic flux intensity patterns in these pipes and the consequent behavior of MsS transducer in inspection of pipes of different materials. The study indicated the role of static magnetic field in an MsS transducer for structural health monitoring (SHM) of pipes used prevalently in domestic and industrial sites. [ABSTRACT FROM AUTHOR]

Occupational exposure to static magnetic fields (SMF) is a concern in relation to magnetic resonance imaging (MRI) system operators. Bodily movements inside the stray field around an MRI system induce an electric current inside the body, and this magnetically induced current can cause temporary sensational changes. Although self-motivated motion control near MRI equipment is recommended in order to prevent these effects, a feasible and safe working procedure is required from a health and safety management viewpoint. In this paper, a procedure involving a restricted access area set at a distance of 30 cm from the end of a 3 T MRI system is compared with a protocol in which self-motivated motion control was used (as recommended by the International Commission on Non-Ionizing Protection guidelines). The effects of this safe working procedure on occupational SMF exposure levels and worker performance were evaluated using Hall sensors and a motion capture system. Subjects performed the protocol for head MRI examination both with and without the proposed safe working procedure. The values for maximum field exposure (peak B) were reduced for all subjects using the safe working procedure. The average peak B also decreased by approximately 26%, compared with the results obtained without any restrictions (conventional protocol) ( $p<0.01$ , $t$ -test). Motion analysis of the subjects indicated that the minimum approach distance to the MRI equipment increased due to the adoption of the restricted access area ( $p<0.05$ , $t$ -test), while slight changes were also observed in sojourn time and the differences of the position along the $z$ -axis ( $\Delta z$ , $p<0.05$ , $t$ -test). However, there were no significant differences in the parameters more closely related to worker performance (e.g., distance moved and velocity) when using the protocols with or without the safe working procedure. These results suggest that this simple safe working procedure may be applied to MRI system operation in order to reduce occupational SMF exposure, without noticeable changes in worker performance. [ABSTRACT FROM AUTHOR]

This paper presents a novel targeted magnetic fluid hyperthermia system. It consists of 12 coils which are deployed symmetrically in the space surrounding the patient. By injecting dc currents to all these coils, and selectively superimposing high frequency ac currents into several coils according to the location of the target point, it is possible to generate a high-frequency alternating magnetic field in the tumor area to heat the nano-particles, so as to kill the tumor cells, while, at the same time, builds up a static magnetic field in the surrounding area to protect the healthy tissues from thermal damage. [ABSTRACT FROM PUBLISHER]

A cord pattern, where magnetic flux density distribution is separated into strong and weak parts like the magnetic domain, appears in magnetic anisotropic numerical calculation results. It is obtained in the strong magnetic anisotropic material. The same cord patterns are also found in the measured magnetic domain structure. Fractal structure of the cord patterns is also observed through the partial enlargement of the calculated cord patterns. The similar cord pattern resembled to the magnetically numerical calculation is also obtained in the structural numerical analysis of the metal crystal level. The fractal cord patterns emerge as a fundamental characteristic of anisotropy in numerical calculation and in physical observations. [ABSTRACT FROM PUBLISHER]

To investigate the characteristics of delayed rectifier potassium channel of cells under moderate intensity static magnetic field, the delayed rectifier potassium channel currents (IK) of acutely isolated mouse prefrontal cortex pyramidal neurons were examined. IK was measured and recorded after the neurons were exposed to 3mT static magnetic field for 15, 30, and 60 min. The results demonstrated that the 3 mT static magnetic field can change the characteristics of delayed rectifier potassium channel and reduce the amplitudes of IK. The maximum activated current densities of control group and 30 min exposure group were respectively 173.61 ± 30.68 pA/pF and 111.80 ± 17.17 pA/pF (n = 10, P < 0.05). The half-activation voltage of the activation curves changed from -1.08 ± 2.17 mV to 10.63 ± 1.51 mV(n = 10, P < 0.05) and the slope factor changed from 22.26 ± 2.99 mV to 17.90 ± 1.85 mV (n = 10, P < 0.05). No change was noted in the inactivation process. The results show that moderate-intensity static magnetic field can change the characteristics of delayed rectifier potassium channel on the cell membrane, and further it may affect the physiological functions of neurons. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the effects of moderate static magnetic field (SMF, 0.2-0.4 T) on experimental murine leukemia and its possible mechanism. As in vivo and in vitro models, normal mice, mice bearing L1210 tumor and L1210 cell line were exposed to moderate SMF, respectively. The results showed that the average lifetime of mice bearing L1210 was prolonged to 12 days by SMF, but just 6 days in the unexposure group. After being exposed to SMF for 10 days, the spleen and thyrnus index of normal mice increased. The L1210 cell proliferation was suppressed by SMF within the first 3 days but enhanced in the following 2 days. These results suggested that the regulating effects of SMF on immune functions may have potential contribution to tumor therapy. [ABSTRACT FROM AUTHOR]

Recent advances in superconducting magnets for medical devices and for magnetic levitation have given rise to the importance of understanding the biological effects of magnetic fields. The purpose of this study was to investigate the effects of strong static magnetic fields on the action potentials of the rat sciatic nerve. A pair of needle electrodes was inserted beneath the skin of the heel for applying electrical stimulations. Compound action potentials of the left sciatic nerve were measured from a pair of electrodes attached to the nerve bundle under static magnetic fields of up to 8 T. We identified the action potentials originating from the Aα and C fibers. The exposure to a static magnetic field did not affect the amplitude of the Aα action potentials. An increase in the static magnetic field increases the amplitudes of the peaks of the C fiber. These results indicated that exposure to strong static magnetic fields enhances the excitation of nerve fibers, and this effect depends on the type of fibers involved. [ABSTRACT FROM AUTHOR]

This paper examines the role of cytoskeletons, such as stress fibers, on magnetic orientation of Schwann cells after strong magnetic field exposure (8-T in maximum). Schwann cells were cultured from dissected sciatic nerves of neonatal rats. Schwann cells oriented parallel to the magnetic field after 60 h of more than 4-T magnetic field exposure. Actin fibers oriented in the direction of the magnetic field after 60 h of 8-T magnetic field exposure but randomly oriented without magnetic field. Orientation of Schwann cells was not observed by inhibiting stress fiber formation using Y-27632, an inhibitor of small guanosine triphosphatases (GTPase) Rho-associated kinase. Our results indicate that the magnetic field elicits reorientation of actin fibers through Rho kinase to allow a response to magnetic orientation of Schwann cells. [ABSTRACT FROM AUTHOR]

The influence of static magnetic fields with intensity of 30-50 mT on the early cleavage division of the sea urchin Echinometra mathaei was investigated. The exposure of fertilized eggs to 30,40, and 50 mT of magnetic fields delayed the onset of early cleavage division. A delay in the first cleavage of 15, 30, and more than 60 min was caused by application of 30, 40, and 50 mT, respectively. The data also showed a significant decrease in cleaved cells for the exposed embryos. Moreover, the exposed eggs to magnetic fields showed more abnormalities compared to the control group. As the intensity of the magnetic field is increased, earlier appearances of abnormalities were observed. That is, deformed fertilization membrane appeared after only 15 min of exposure to 50 mT compared to 30 min in 30 and 40 mT exposures and 90-105 min in the control group. [ABSTRACT FROM AUTHOR]