Diamagnetic Force Research Articles

Lateral force calibration of an atomic force microscope with a diamagnetic levitation spring system

A novel diamagnetic lateral force calibrator (D-LFC) has been developed to directly calibrate atomic force microscope (AFM) cantilever-tip or -bead assemblies. This enables an AFM to accurately measure the lateral forces encountered in friction or biomechanical-testing experiments at a small length scale. In the process of development, deformation characteristics of the AFM cantilever assemblies under frictional loading have been analyzed and four essential response variables, i.e., force constants, of the assembly have been identified. Calibration of the lateral force constant and the “crosstalk” lateral force constant, among the four, provides the capability of measuring absolute AFM lateral forces. The D-LFC is composed of four NdFeB magnets and a diamagnetic pyrolytic graphite sheet, which can calibrate the two constants with an accuracy on the order of 0.1%. Preparation of the D-LFC and the data processing required to get the force constants is significantly simpler than any other calibration methods. The most up-to-date calibration technique, known as the “wedge method,” calibrates mainly one of the two constants and, if the crosstalk effect is properly analyzed, is primarily applicable to a sharp tip. In contrast, the D-LFC can calibrate both constants simultaneously for AFM tips or beads with any radius of curvature. These capabilities can extend the applicability of AFM lateral force measurement to studies of anisotropic multiscale friction processes and biomechanical behavior of cells and molecules under combined loading. Details of the D-LFC method as well as a comparison with the wedge method are provided in this article.

Cleavage and survival of Xenopus embryos exposed to 8 T static magnetic fields in a rotating clinostat

In this study, we examined cleavage and survival of fertilized Xenopus embryos exposed to 8 T static magnetic fields (SMFs). We investigated fertilized Xenopus embryos exposed to magnetic field either in static chamber or in a rotating culture system. Our results showed that the exposure to the strong magnetic field of 8 T changed the third cleavage furrow from the usual horizontal one to a perpendicular one; however, when the direction of gravity was randomized by exposing embryos to magnetic field in a rotating culture system, the third cleavage furrow were formed horizontally, a finding which suggests that the observed distortion of the third cleavage furrow in magnetism-exposed embryos was accomplished by altering gravity effects which were elicited by diamagnetic force due to high gradient magnetic field. Our results also showed that the exposure to the strong magnetic field did not damage survival. These results demonstrate that SMF and altering gravity cause distortion of the third cleavage furrow and show that effects of exposing cleavage embryos to magnetic field were transient and did not affect the post-cleavage development. We also showed that strong magnetic field is not hazardous to the cleavage and blastula-gastrula transition of developing embryonic cells.

Diamagnetic and Expansion Effects on the Observable Properties of the Slow Solar Wind in a Coronal Streamer

The plasma density enhancements recently observed by the Large-Angle Spectrometric Coronagraph (LASCO) instrument on board the Solar and Heliospheric Observatory (SOHO) spacecraft have sparked considerable interest. In our previous theoretical study of the formation and initial motion of these density enhancements it is found that beyond the helmet cusp of a coronal streamer the magnetized wake configuration is resistively unstable, that a traveling magnetic island develops at the center of the streamer, and that density enhancements occur within the magnetic islands. As the massive magnetic island travels outward, both its speed and width increase. The island passively traces the acceleration of the inner part of the wake. In the present paper a few spherical geometry effects are included, taking into account both the radial divergence of the magnetic field lines and the average expansion undergone by a parcel of plasma propagating outward, using the expanding box model (EBM), and the diamagnetic force due to the overall magnetic field radial gradients, the so-called melon-seed force. It is found that the values of the acceleration and density contrasts can be in good agreement with LASCO observations, provided the spherical divergence of the magnetic lines starts beyond a critical distance from the Sun and the initial stage of the formation and acceleration of the plasmoid is due to the Cartesian evolution of MHD instabilities. This result provides a constraint on the topology of the magnetic field in the coronal streamer.

Strong static magnetic field effects on yeast proliferation and distribution

The present study focuses on the effects of gradient magnetic fields on the behavior of yeast, such as its proliferation and mass distribution, and evaluates the effects of magnetism on materials in the yeast culture system. Yeast, Saccharomyces cerevisiae, was incubated in a liquid medium under magnetic fields (flux density B=14 T). When yeast in a tube was exposed to 9–14 T magnetic fields with a maximum flux density gradient of d B/d x=94 T/m, where x is the space coordinate, the rate of yeast proliferation under the magnetic fields decreased after 16 h of incubation compared to that of the control group. The physical properties of the yeast culture system were investigated to discover the mechanism responsible for the observed deceleration in yeast proliferation under magnetic fields. Gas pressure inside the yeast culture flask was compared with and without exposure to a magnetic field. The results suggested that the gas pressure inside a flask with 6 T, 60 T/m slowly increased in comparison to the pressure inside a control tube. Due to the diamagnetism of water (medium solution) and yeast, the liquid surface distinctly inclined under gradient magnetic fields, and the hydrostatic force in suspension was strengthened by the diamagnetic forces. In addition, magnetophoresis of the yeast cells in the medium solution exhibited localization of the yeast sedimentation pattern. The roles of magnetically changed gas-transport processes, hydrostatic pressures acting on the yeast, and changes in the distribution of the yeast sedimentation, as well as the possible effects of magnetic fields on yeast respiratory systems in the observed disturbance of the proliferation are discussed.

Potential magnetic fields around flux ropes

A method of calculation of potential magnetic fields around cylindrical and toroidal flux ropes is presented. The flux rope has an arbitrary orientation with respect to ambient field. The problem is solved analytically. Expressions for the magnetic field components, diamagnetic force, and its moment are found. Results obtained can be used for estimations of magnetic forces in systems where magnetic flux ropes and potential fields coexist, e.g., in the solar corona.

Polarized light transmission of smooth muscle cells during magnetic field exposures

Strong static magnetic fields in the Tesla range have a diamagnetic force on cell components. Within an exposure period of 3 d, such magnetic fields generate a clear alignment of the smooth muscle cell assembly, which is parallel to the direction of the fields. In the present study, behavioral changes in intracellular components were suggested by changes in optical transmission under the influence of magnetic fields of 8 T. The magnetically oriented cells were exposed both in parallel and perpendicularly to the 8 T magnetic fields, and the time course of the polarized light transmission at 500 nm was measured in real time. The perpendicularly exposed cells had a presteady state, which was slow to increase. However, the total change in the intensity of the polarized light was larger than that of the cells exposed in parallel. We observed that no distinct changes in cell morphology including cell membrane components occurred during the 3 h of exposure to the magnetic fields. Based on the results, we concluded that intracellular component motion had a major influence on polarized light transmission under 8 T magnetic fields. We speculated that unconstrained intracellular macromolecules, such as actin fibers and microtubules, rotated due to diamagnetic torque forces during the 3 h of exposure to 8 T magnetic fields.

Magnetosensitive enzyme electrode for hydrogen peroxide sensing

Peroxidase is one of the magnetosensitive enzymes, and has an important role in scavenging reactive oxygen species. In the present study, a surface of platinum black electrode was laminated by peroxidase molecules, and H2O2 decomposing processes by peroxidase and platinum black were monitored with and without magnetic fields of up to 14 T. An increase in the current reflected a decrease in the activity of peroxidase molecules. The current in the electrode with peroxidase increased significantly depending on the applied magnetic flux intensity. The increases of current during the magnetic field exposures were observed consistently both when the currents were transiently decreasing and at a constant level. It is suggested that the layers of peroxidase molecules on the platinum black cause a distortion by diamagnetic forces acting on the layers, and the distortion is concentrated on a catalytic part in the peroxidase resulting in the observed activity decreases.

Effects of intense magnetic fields on sedimentation pattern and gene expression profile in budding yeast

Effects of magnetic fields (MFs) on biological systems are usually investigated using biological indices such as gene expression profiles. However, to precisely evaluate the biological effects of MF, the effects of intense MFs on systematic material transport processes including experimental environment must be seriously taken into consideration. In this study, a culture of the budding yeast, Saccharomyces cerevisiae, was used as a model for an in vitro biological test system. After exposure to 5 T static vertical MF, we found a difference in the sedimentation pattern of cells depending on the location of the dish in the magnet bore. Sedimented cells were localized in the center of the dish when they were placed in the lower part of the magnet bore while the sedimentation of the cells was uniform in dishes placed in the upper part of the bore because of the diamagnetic force. Genome wide gene expression profile of the yeast cells after exposure to 5 T static MF for 2 h suggested that the MF did not affect the expression level of any gene in yeast cells although the sedimentation pattern was altered. In addition, exposure to 10 T for 1 h and 5 T for 24 h also did not affect the gene expression. On the other hand, a slight change in expressions of several genes which are related to respiration was observed by exposure to a 14 T static MF for 24 h. The necessity of estimating the indirect effects of MFs on a study of its biological effect of MF in vitro will be discussed.

Magnetic field effects on assembly pattern of smooth muscle cells

Under a strong magnetic field, the diamagnetic properties of biological cells modulate the behavior of the cells themselves, under conditions of both floating and adherence. The morphological effects of strong static magnetic fields on adherent cells are less well understood than the effects of magnetic fields on red blood cells. In the present study, a high-intensity magnetic field of 14 T affected the morphology of smooth muscle cell assemblies, and the shapes of the cell colonies extended along the direction of the magnetic flux. The phenomenon was most notable under magnetic fields of more than 10 T, where an ellipsoidal pattern of smooth muscle cell colonies was clearly observed. The ellipticity of the cell colony pattern with a 14-T magnetic field was 1.3, whereas that with a field of 0-8 T was close to a circle at about 1.0. The evidence that smooth muscle cells detect high-density magnetic flux and thus change their cell orientation was shown as a visible pattern of cellular colonies. The speculated mechanism is a diamagnetic torque force acting on cytoskeleton fibers, which are dynamically polymerizing-depolymerizing during cell division and cell migration.

On the motion of charged particles in a sheared force-free magnetic field

This paper considers single-particle trajectories in a planar sheared force-free magnetic field. A specific feature of this magnetic configuration is the absence of both gradient and curvature magnetic drifts, as well as a diamagnetic force along field lines. Therefore, in the framework of the drift approximation, the motion of the particle guiding centre does not feel the magnetic field's non-uniformity. Here we discuss how the latter affects actual particle trajectories, making them quite different from simple circular gyromotion even when the Larmor radius is small. It is also shown how magnetic confinement ceases to work when the Larmor radius becomes comparable to the spatial scale of the field variation.

Propagation of a toroidal magnetic cloud in interplanetary space

We studied dynamics of a compact toroid in interplanetary space considering the diamagnetic force, gravity, and the drag force of the ambient solar wind. Magnetic cloud velocity profiles were calculated for different initial speeds using an expression of the diamagnetic force in purely toroidal coordinates.

強磁場下での細胞内骨格再配置のリアルタイム偏光検出

A real-time monitoring system utilizing linearly polarized light was developed for observing intracellular cytoskeleton protein motion and the possible effects of strong static magnetic fields on cell behavior. Smooth muscle cells of a rat were cultured in a petri dish for one day, then were set between a pair of light-polarizing plates, whose polarizing directions were normal to each other and inclined almost 45 degrees against the direction of the magnetic field. The polarized light transmission through the adhering cell layer was measured in real time under magnetic fields of up to 14 T. During the magnetic field exposures, the light transmission increased 50% and reached a stable level within 3 hours. The results indicated that the intracellular cyto-skeleton proteins rotated due to the diamagnetic torque force acting on them.

Magnetophoresis of diamagnetic cells and microorganisms in a culture medium

In the present study, the magnetophoresis of three types of diamagnetic cells was observed under gradient magnetic fields. The predicted mechanism of the cell's magnetophoresis, the drifting of cells in gradient magnetic fields, was attributable to the difference in the diamagnetic forces on water and the cell. The spatial density gradient of the cells, which resulted from the magnetophoresis, was measured by an optical transmission measurement after exposure to magnetic fields of 9-14 T with a maximum gradient of 94 T/m. In the case of smooth muscle cells, adherent cells, the long-term and short-term digestion of cells by the enzyme trypsin resulted in an increased cell density distribution under high magnetic fields and an increase under low magnetic fields, respectively. In the experiments with yeast and blood platelets, the cells moved downward to the lower magnetic fields in the chamber, and a visible density distribution change was observed.

Dynamics of a toroidal magnetic cloud in the solar wind

Knowledge about the behavior of compact toroidal magnetic force‐free objects in ambient magnetic field may help to better understand dynamical processes in association with coronal mass ejections and their interplanetary counterparts. The problem to find the diamagnetic force acting on a toroidal object in an inhomogeneous magnetic field is solved analytically. At first the drapery of the inhomogeneous magnetic field caused by an insertion of a toroid was found, and then the force acting on the toroid by this disturbed magnetic field was obtained. The problem is considered in purely toroidal coordinates. The obtained solution can be used for calculations of the repulsing diamagnetic force acting on isolated objects in the solar corona such as magnetic clouds of a toroidal shape and for the determination of their velocity profiles. Deformations of toroidal transients due to this melon seed force are not investigated here. Only the force acting on the toroid as a whole is taken in consideration.

Dynamical behavior of granular matter in low gravity (diamagnetic levitation)

We report studies on the dynamics of macroscopic particles in a low-gravity ‘magnetic levitation’ environment. In a real sense, this allows the investigation of new states of granular matter. Particle ensembles (rods, spheres, or grains) can be held in a weak confining potential due to diamagnetic forces in a high-field-resistive magnet. In such a case ‘ kT’ is not zero, and assemblies of particles undergo ergodic processes to find the lowest configurational ground state. This new area presents unique problems for video data acquisition and mathematical descriptions of the complex dynamic motions, interactions, and configurations of single and multiple particle assemblies. Three examples of such processes are presented.

Diamagnetism and magnetic force: a new laboratory for granular materials and chaotic/deterministic dynamics

We report studies on the dynamics of macroscopic particles in a low gravity “magnetic levitation” environment. Particle ensembles are held in a weak confining potential due to diamagnetic forces in a high-field resistive magnet. In such a case, the kinetic energy is not zero, and assemblies of particles undergo ergodic processes to find the lowest configurational ground state. Examples of such processes, as well as consideration of chaotic versus deterministic motion for single-particle orbits, will be presented.

Detection of earth rotation with a diamagnetically levitating gyroscope

Strong magnetic fields allow levitation of apparently nonmagnetic substances due to their weak but not negligible diamagnetic response of about 10 −5. Importantly, the diamagnetic force compensates gravity on the level of individual atoms and molecules and, therefore, can be used to mimic a continuous zero-gravity environment that, otherwise, is only achievable on board of a space station. Here we employ this earth-bound low gravity to demonstrate a simple mechanical gyroscope with sensitivity already comparable to that achieved by quantum and military gyroscopes. Our gyroscope can serve as a “shooting range” for the development of precision orbiting gyroscopes that have been a subject of intensive discussions regarding possible tests of general relativity.

Diamagnetic Force Acting on Electron Beams in Superconducting Tubes

In this paper, the diamagnetic force, due to the Meissner effect, acting on the electron beam of finite radius which runs through the superconducting tube, is calculated. The effects of the diamagnetic force are theoretically studied. The diamagnetic force guides the electron beam toward the tube axis and conforms the shape of the cross section of the beam. However, it does not yield the focusing of a single beam of finite radius.

Making water levitate

The levitation in air of water, other diamagnetic substances1 and even living organisms2 was recently achieved by using the extremely strong magnetic field provided by a Bitter-type hybrid magnet. We too have succeeded in levitating water, but in the lower fields of an ordinary 10 T superconducting magnet. To achieve this we make use of gravitational and magnetically induced buoyancy forces in the host paramagnetic atmosphere (pressurized air or oxygen), rather than simply the diamagnetic force on the levitating object, to balance the gravitational force. This permits the magnetic levitation in air of paramagnetic as well as diamagnetic substances, which was widely believed to be impossible3. The physics underlying this effect is essentially the same as that of magnetohydrostatic ore separation, where a ferromagnetic fluid is used4. Because our process can levitate subtances at a stable position in an atmosphere, we have named it ‘magneto-Archimedes levitation’.

Poetry and Terror in Peter Dale Scott's "Coming to Jakarta"

In Peter Dale Scott's forthcoming work, Minding the Darkness, he asks ...did he [David Horowitz] perhaps have a point / about the left's too willing // suspension of judgement? This is the kind of question, calling for an evaluation of one's political beliefs and strategies, that is typical of Scott's recent poetry. Scott's work is one example of a that counters the familiar complaints about contemporary poetry's political irrelevance. His is very much about politics in the late twentieth century. But I would suggest that the political meaning of Scott's work is not located just in his subject matter or the questions that he raises; rather, the politics of his are also determined by the way in which he involves his audience in his project of self-critique. His poems challenge those of us with the time and inclination to peruse Chicago Review or to pick up a New Directions volume of to think about our own role in shaping the institutions and practices of political power. In this essay I argue that Scott's invitation to his readers to recognize our complicity with the terrors effected by our political institutions is especially apparent in the first book of his trilogy, Coming to Jakarta. Coming to Jakarta has three principle subjects, and one of the goals of the poem is to determine a useful relationship between them. The poem opens: There are three desks in my office at one I read Virgil's descent into the underworld at one I try to sort out clippings of failed Swiss banks or of slow killings on meat-hooks in a well-guarded Chicago garage but the third desk this one is where the typewriter stares at me with only a sheet of white paper from which my blank mind is averted with an unmistakable almost diamagnetic force The subjects of this poem are politics, poetry, and Scott himself as he tries to find a way to write about them. The most shocking revelations of Jakarta occur when Scott reveals the U.S. government's involvement in the 1965 massacres in Indonesia, when as many as half a million people were killed over the course of a few months. Scott documents his accusations with marginal references and an extensive bibliography, though he does once take advantage of the fact that he is writing precisely poetry to hazard an informed but unsubstantiated guess about one man's connection to the massacres. But with the exception of his authorization to make this one guess, what recommends this subject matter to poetry? In interviews Scott notes that he first began this poem because he could not get his investigation of the massacre published in any other form. This censorship was a boon for poetry, however, for it spurred Scott to make a poem out of this material, and in so doing he also began to investigate his own - and our - involvement in the perpetuation of the conditions under which such a horrific event could have taken place. Because Scott takes on issues of political import through a lyric that encourages self-reflection, he leads both himself and us to consider the connection between ourselves and the work of states and corporations that we like to think of as removed from ourselves. Large sections of the poem are devoted to speculation on the causes of the massacre. In one section he questions the results of the intersection of U.S. economic and political interests in Indonesia, interests that included the United States' desire to keep the country from becoming a communist domino falling toward Australia or Indochina, and U.S. corporations' investments in extracting maximum profits from the land. After noting the Cold-War choices between nuclear Armageddon or Jonestown mass-suicide, Scott asks: And what if the choices in Java were just as simple - to become a technological graveyard or a Malthusian one rice production beginning to give way to high-yield low-nutrition cassava till petty landlords rid themselves of peasants who had taken over the fields to enforce the government's ineffectual land reform (125) The italicized section in this passage is a quote from Robert Shaplen's Time Out of Hand. …