STUDY OF THE EFFECT OF MAGNETIC FIELD ON MR SUSPENSIONS BASED ON JET IMAGES

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1270-1275
Author(s):  
I. LATERZA FILHO ◽  
EDVALDO SABADINI ◽  
M. I. ALKSCHBIRS ◽  
P. L. O. VOLPE ◽  
ANTONIO J. F. BOMBARD
Keyword(s):  
Magnetic Field ◽  
Applied Pressure ◽  
Ccd Camera ◽  
Specific Pressure ◽  
Promising Application ◽  
Jet Oscillation ◽  
The Magnetic Field ◽  
Initial Results ◽  
Very High ◽  
Jet Images

Suspensions of carbonyl iron powder in oil (CIP/O) have a very promising application on controlled fluids processes, as a very high local viscosity can be produced in the region in which the magnetic field is applied, allowing some control of the flow. In experiments performed in tube viscometers the flow can be completely stopped in some circumstances, such as specific pressure, magnetic field strength and particles concentration. This work presents our initial results of the jet morphology produced at the tip of the tube of a CIP/O, in terms of the applied pressure or of the applied magnetic field. A 3-CCD camera positioned in front of the jet collected "frozen" pictures of the jets produced in different conditions. Morphologic parameters of the jet such as the angle of the cone and the amplitude of the jet oscillation can be measured. Thus, the effect of the magnetic field on the fluid can be visualized and parameterized. It was observed that the perturbation due to the application of the magnetic field on the tip of the tube causes large changes on the jet oscillation. The amplitudes of the oscillations are very sensitive to the parameters described above.

High magnetic field NMR investigation of the spin density wave phase of TMTSF2PF6

2002 ◽  
Vol 12 (9) ◽  
pp. 389-389
Author(s):  
W. G. Clark ◽  
F. Zamborsky ◽  
B. Alavi ◽  
P. Vonlanthen ◽  
W. Moulton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Proton Relaxation ◽  
High Magnetic Fields ◽  
Organic Conductor ◽  
First Order ◽  
The Magnetic Field ◽  
Very High

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.

scholarly journals Ephemeral states in protein folding under force captured with a magnetic tweezers design

2019 ◽  
Vol 116 (16) ◽  
pp. 7873-7878 ◽  
Author(s):  
Rafael Tapia-Rojo ◽  
Edward C. Eckels ◽  
Julio M. Fernández
Keyword(s):  
Magnetic Field ◽  
Molten Globule ◽  
Magnetic Tweezers ◽  
Protein L ◽  
High Frequencies ◽  
Electric Signals ◽  
Very High Frequencies ◽  
The Magnetic Field ◽  
Very High ◽  
Unique Capability

Magnetic tape heads are ubiquitously used to read and record on magnetic tapes in technologies as diverse as old VHS tapes, modern hard-drive disks, or magnetic bands on credit cards. Their design highlights the ability to convert electric signals into fluctuations of the magnetic field at very high frequencies, which is essential for the high-density storage demanded nowadays. Here, we twist this conventional use of tape heads to implement one in a magnetic tweezers design, which offers the unique capability of changing the force with a bandwidth of ∼10 kHz. We calibrate our instrument by developing an analytical expression that predicts the magnetic force acting on a superparamagnetic bead based on the Karlqvist approximation of the magnetic field created by a tape head. This theory is validated by measuring the force dependence of protein L unfolding/folding step sizes and the folding properties of the R3 talin domain. We demonstrate the potential of our instrument by carrying out millisecond-long quenches to capture the formation of the ephemeral molten globule state in protein L, which has never been observed before. Our instrument provides the capability of interrogating individual molecules under fast-changing forces with a control and resolution below a fraction of a piconewton, opening a range of force spectroscopy protocols to study protein dynamics under force.

MAGNETO-OPTICAL ROTATION IN VERY HIGH FIELDS

1960 ◽  
Vol 38 (7) ◽  
pp. 941-944 ◽  
Author(s):  
Richard Stevenson
Keyword(s):  
Magnetic Field ◽  
High Field ◽  
Optical Rotation ◽  
Field Limit ◽  
Electron Theory ◽  
Important Data ◽  
Kerr Rotation ◽  
High Fields ◽  
The Magnetic Field ◽  
Very High

Magneto-optical rotation by transmission through or reflection from solids is examined by the classical free electron theory, with the view of taking such a measurement using fields in the megagauss range. In general the rotation is a markedly non-linear function of the magnetic field, and in some cases can change in sign as the field increases. For very low fields the rotation varies directly with B, but in the high field limit the rotation varies inversely with the field. For substances in which the intercollision time of the electron is small, measurements of the Kerr rotation (i.e. by reflection) will give the electron mobility as a function of the magnetic field, and thus will give important data which can be used in conjunction with high field magnetoresistance experiments.

scholarly journals The revived Penrose process can power the central engine in active galactic nuclei

1986 ◽  
Vol 119 ◽  
pp. 395-398
Author(s):  
Sanjay M. Wagh ◽  
N. Dadhich
Keyword(s):  
Magnetic Field ◽  
Active Galactic Nuclei ◽  
Extraction Efficiency ◽  
Galactic Nuclei ◽  
High Energy ◽  
Energy Extraction ◽  
Central Engine ◽  
Penrose Process ◽  
The Magnetic Field ◽  
Very High

Using the fact that the efficiency of the revived (Wagh et al 1985) Penrose process of energy extraction from black holes immersed in electromagnetic fields can be very high (Parthasarathy et al, 1986) we show that this process can comfortably power the ‘central engine’ in Active Galactic Nuclei. The microphysical Penrose process energized particles will be ultrarelativistic in the asymptotic frame. Hence the kinematical analysis of escaping photons by Piran and Shaham (1977) will be a good approximation to the kinematics of these particles. From this analysis one expects the energized particles to emerge within an angle∼ 40° above and below the equatorial plane. These energetic particles, which are collimated in the funnel of an accretion disk and further on by the magnetic field, then, form supersonic, relativistic, bilateral jets. The relativistic Y factor for such jets can be expected to be ∼ 2 since these ultrarelativistic particles will effectively mimick radiation in ‘dragging’ the matter already injected inside the funnel. Various implications of high energy extraction efficiency are illustrated.

Strong magnetic field of the peculiar red supergiant VY Canis Majoris

2017 ◽  
Vol 13 (S336) ◽  
pp. 391-392
Author(s):  
Hiroko Shinnaga ◽  
Mark J. Claussen ◽  
Satoshi Yamamoto ◽  
Shimojo Masumi
Keyword(s):  
Magnetic Field ◽  
Stellar Evolution ◽  
Field Measurements ◽  
Circumstellar Envelope ◽  
Magnetic Field Measurements ◽  
High Degree ◽  
The Magnetic Field ◽  
Very High ◽  
Measured Magnetic Field ◽  
Field Strengths

AbstractWe report on magnetic field measurements associated with the well-known extreme red supergiant (RSG), VY Canis Majoris (VY CMa). We measured both linear and circular polarization of the SiO v = 0, J = 1 − 0 transition using a sensitive radio interferometer. The measured magnetic field strengths are surprisingly high. A lower limit for the field strength is expected to be at least ~ 10 Gauss based on the high degree of linear polarization. Since the field strengths are very high, the magnetic field must be a key element in understanding the stellar evolution of VY CMa as well as the dynamical and chemical evolution of the complex circumstellar envelope of the star.

scholarly journals The magnetic field of IRAS 16293-2422 as traced by shock-induced H2O masers

2012 ◽  
Vol 8 (S287) ◽  
pp. 74-78
Author(s):  
Felipe O. Alves ◽  
Wouter H. T. Vlemmings ◽  
Josep M. Girart ◽  
José M. Torrelles
Keyword(s):  
Magnetic Field ◽  
Particle Density ◽  
High Density ◽  
Line Of Sight ◽  
Very Large Array ◽  
Compressed Gas ◽  
Post Shock ◽  
Low Mass ◽  
The Magnetic Field ◽  
Very High

AbstractH2O masers are important magnetic field tracers in very high density gas. We show one of the first magnetic field determinations at such high density in a low-mass protostar: IRAS 16293-2422. We used the Very Large Array (VLA) to carry out spectro-polarimetric observations of the 22 GHz Zeeman emission of H2O masers. A blend of at least three maser features can be inferred from our data. They are excited in zones of compressed gas produced by shocks between the outflows ejected by this source and the ambient gas. The post-shock particle density is in the range 1 - 3 × 109 cmt−3, and the line-of-sight component of the magnetic field is estimated as ~ 113 mG. The outflow dynamics is likely magnetically dominated.

Liquid-metal flow in a system of electrically coupled U-bends in a strong uniform magnetic field

1995 ◽  
Vol 299 ◽  
pp. 73-95 ◽  
Author(s):  
Sergei Molokov ◽  
Robert Stieglitz
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Liquid Metal ◽  
Uniform Magnetic Field ◽  
Flow Direction ◽  
Metal Flow ◽  
Three Dimensional ◽  
Recirculatory Flow ◽  
The Magnetic Field ◽  
Very High

Liquid-metal magnetohydrodynamic flow in a system of electrically coupled U-bends in a strong uniform magnetic field is studied. The ducts composing the bends are electrically conducting and have rectangular cross-sections. It has been anticipated that very strong global electric currents are induced in the system, which modify the flow pattern and produce a very high pressure drop compared to the flow in a single U-bend. A detailed asymptotic analysis of flow for high values of the Harmann number (in fusion blanket applications of the order of 103−104) shows that circulation of global currents results in several types of peculiar flow patterns. In ducts parallel to the magnetic field a combination of helical and recirculatory flow types may be present and vary from one bend to another. The magnitude of the recirculatory motion may become very high depending on the flow-rate distribution between the bends in the system. The recirculatory flow may account for about 50% of the flow in all bends. In addition there are equal and opposite jets at the walls parallel to the magnetic field, which are common to any two bends. The pressure drop due to three-dimensional effects linearly increases with the number of bends in a system and may significantly affect the total pressure drop. To suppress this and some other unwelcome tendencies either the ducts perpendicular to the magnetic field should be electrically separated, or the flow direction in the neighbouring ducts should be made opposite, so that leakage currents cancel each other.

scholarly journals A first look into the magnetic field configuration of prominence threads using spectropolarimetric data

2013 ◽  
Vol 8 (S300) ◽  
pp. 112-116
Author(s):  
D. Orozco Suárez ◽  
A. Asensio Ramos ◽  
J. Trujillo Bueno
Keyword(s):  
Magnetic Field ◽  
High Spatial Resolution ◽  
Zeeman Effect ◽  
Field Vector ◽  
Field Configuration ◽  
Magnetic Field Vector ◽  
Solar Prominence ◽  
Physical Processes ◽  
The Magnetic Field ◽  
Initial Results

AbstractWe show preliminary results of an ongoing investigation aimed at determining the configuration of the magnetic field vector in the threads of a quiescent hedgerow solar prominence using high-spatial resolution spectropolarimetric observations taken in the He I 1083.0 nm multiplet. The data consist of a two-dimensional map of a quiescent hedgerow prominence showing vertical threads. The observations were obtained with the Tenerife Infrared Polarimeter attached to the German Vacuum Tower Telescope at the Observatorio del Teide (Spain). The He I 1083.0 nm Stokes signals are interpreted with an inversion code, which takes into account the key physical processes that generate and/or modify circular and linear polarization signals in the He I 1083.0 nm triplet: the Zeeman effect, anisotropic radiation pumping, and the Hanle effect. We present initial results of the inversions, i.e, the strength and orientation of the magnetic field vector along the prominence and in prominence threads.

On the Statistics of AM Herculis Binaries

1995 ◽  
Vol 12 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Kinwah Wu ◽  
Dayal T. Wickramasinghe ◽  
Jianke Li
Keyword(s):  
Magnetic Field ◽  
Orbital Period ◽  
High Field ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Cataclysmic Variable ◽  
The Difference ◽  
The Magnetic Field ◽  
Very High

AbstractThe magnetic field and orbital period distributions of AM Herculis binaries are investigated. Our study shows that (i) there is a significant lack of very-high-field magnetic white dwarfs in binaries when compared with isolated white dwarfs, and (ii) the difference between the period distributions of AM Herculis binaries and other cataclysmic variable subclasses is statistically significant. These results imply that the evolution and the birth of AM Herculis binaries are different from those of other cataclysmic variables.

scholarly journals Radio and X-Ray Observations of Large Scale Jets in Quasars

1982 ◽  
Vol 97 ◽  
pp. 129-131
Author(s):  
J. F. C. Wardle ◽  
R. I. Potash
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
External Pressure ◽  
Hot Gas ◽  
Radio Lobe ◽  
Outer Lobe ◽  
5 Ghz ◽  
High Degree ◽  
The Magnetic Field ◽  
Very High

The first big radio jet to be found in a quasar was in 4C32.69 (z=.659) (Potash and Wardle, 1980). A new higher resolution map of this jet, made with the VLA at 5 GHz, is shown in Fig. 1. Observationally the important points are 1) it is very luminous, 2) it is very well collimated, 3) the magnetic field is parallel to the jet over its entire length, 4) it bends at least three times along its path to the outer radio lobe. Physically this is interesting because 1) it is a very lossy pipeline to the outer lobe, 2) the high degree of collimation suggests either the jet is confined by external pressure or it is highly supersonic. But the minimum internal energy density is very high (>3×10–10 erg cm–3), so if it is confined the external pressure must also be very high. On the other hand, if the jet is expanding freely, it is easy to show that the momentum flux is enormous (>4×1038 dynes). Such a jet is very rigid. It is difficult to stop and difficult to bend, but evidently both of these things happen. A detailed discussion of these problems is given in Potash & Wardle (1980), who concluded that the jet cannot be expanding freely. They suggested that the jet might be confined either by the thermal pressure of external hot gas, or by a helical component of magnetic field due to currents in the jet.

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