Magnetic gradient

Majetich and coworkers have studied magnetic properties of carbon-coated Co[32], Gd2C3, and FIo2C3 nanocrystals[33] formed in the chamber soot. A brief account on the coated Co nanocrystals is given here. They extracted magnetic nanocrystals from the crude soot with a magnetic gradient field technique. 

Small signal unit Magnet Gradient coil RF coil... 

We need to apply temporal variation of magnetic gradient for localization of the spins between the 90° RF pulse and the echo detection, which is typically in a range of millisecond. In MRI experiments, the sample is divided into either a two-dimensional... 

A possible glimpse of the future is provided by Figure 8.12, which shows a schematic illustration of a magnetic-gradient trap for anti-atom spectroscopy. The scenario described below is due to Hansch and Zimmer-... 

Noise levels MRI scanners used rapidly switching magnetic gradients and as the coils expand and contract, high auditory noises and vibrations, which can reach 130dB (the sound intensity of a jet engine), can be emitted, so appropriate ear protection is required. 

Peripheral nerve stimulation the rapidly switching magnetic gradients can also stimulate muscles and peripheral nerves. This may thus be reported as a twitching sensation, particularly at the body extremities. Guidelines have been introduced to limit the rate of switching, aiming to avoid this effect. 

In Eq. (6.8) the first term is the phase shift due to the static magnetic field and the second term is the phase shift due to the magnetic gradient pulse applied along the z-direction. The next step is applying a 180° rf pulse, which inverts the sign of the precession and the phase as depicted in Fig. 6.1. At time N -F A a second identical pulse gradient is applied which cancels out the induced phase shifts,... 

Fig. 6.1.9. 200 MHz spectra of H pertaining to spin diffusion experiments on a nylon 6,6 PBZT blend (VanderHart [46]). Left, magnetization gradient created by dipolar echo sequence with spacing 30 [xs, thus, initially favoring the PBZT portion of the blend. Right, results of spin diffusion observed using CRAMPS to obtain high resolution proton NMR of the blend, and observation of magnetization transfer between the phenyl protons of the PBZT, and the methylene protons of the nylon 6,6.

Consider wet processing for particle diameter <6 mm to minimize dusting and electrostatics. For particle diameter >150 pm, prefer wet belt <150 pm, prefer wet drum. Match magnetic gradient to the diameters of the particles. Match the machine to the liberation size (liberation size is 0.01 of the diameter of the mineral crystal). For wet machines, pump 4 Mg water/Mg sohds, although 90% of the water can be recirculated. 

Fig. 11. Onset of nonexponential decay in liquid HP xenon due to dipolar fields. Open circles show envelope of the transverse magnetization signal obtained with CPMG pulse sequence for r = 100ms and an applied longitudinal field gradient di/Ez/dz = 1.4mGcm Solid line is a model of the initial magnetization gradient growth with no free parameters. (Courtesy of Michael Romalis. Reprinted from Ref. 224 with permission. Copyright 2001, The American Physical Society.)...

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