Special Spinning Methods

The development of new ID and 2D pulse sequences enables the spectroscopist to obtain structure and dynamic information about systems that were previously very hard to study. As an example is reported in Fig. 3.2.13 the 2D spectrum of erythromycin A measured with the FIREMAT (Five p Replicated Magic Angle Turning ) technique [30]. The slow spinning speed of 390 Hz produces a spinning sideband pattern for each peak in one dimension, whereas a multipulse sequence in combination with a special processing method produces isotropic lines in the second dimension. 

Furthermore, there have been developed special pulse methods (DEFT and SEFT, i.e. driven equilibrium Fourier transform and spin-echo Fourier transform method) for extremely slowly relaxing The cosine... 

Melt-spinning method The melt-spinning of PVC is conducted using an extruder [145], As PVC easily decomposes and carbonizes when heated for a long time, it cannot be transported in a molten state. Since viscosity of molten PVC is high, gear pumps cannot be used in the meltspinning of PVC. Also, special attention must be paid to its thermal stability and fluidity. 

Kevlar fibers [22] were the first application of liquid crystals in polymers. A special technique had to be developed spin fibers because they were too stiff to be processed by the known fiber spinning methods. The straight stiff nature of these chains however confers exceptional strength on the final Kevlar fiber. 

Spin welding is just a special form of vibration welding. Because it is such a popular technique, it is considered a special assembly method. 

Chapt. 6.4/6.S] which requires special equipment. In this two-dimensional sample spinning method, the angle of rotation with respect to the external magnetic field is different in the evolution and detection period, respectively (Fig. 28.a). The method relies on the fact, that a fast rotation around an axis with an angle r with respect to the external magnetic field results in the scaling of the powder pattern with a scaling factor... 

This result is remarkably simple as compared to the usual methods. For a spin-polarised potential V, Kraft, Oppeneer, Antonov and Eschrig (1995) used the elimination method and found the corrections as a sum of 9 terms, which is equivalent to our Eq.(ll). They notice that three terms of their sum have a known physical meaning (spin-orbit, Darwin and mass-velocity corrections), but the other terms have no special name . 

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