Solids, imaging

The rf pulses for 27A1 NMR experiments were calibrated using an aqueous solution of A1C13. For the rf power level attenuated by 10 dB, the duration of the 180 "-pulse of the broadband probe was 60 ps. All solids imaging experiments were performed with t => 300 ps and the nominal flip angle a = 90°/(J + 1/2). The two pulses had the same amplitude and for 27A1 MRI were 10- and 20-ps long, respectively. 

Another issue of concern is the amplitude of magnetic field gradients required for solids imaging. For spectra up to a few kHz wide, standard frequency encoding schemes can be used to obtain reasonable spatial resolution. This will not work for broader lines, but it is well known that phase encoding is much more tolerant to line broadening and can be used for spectral widths in excess of 100 kHz with no major loss in spatial resolution. 

Figure 1.15 Helical hybrid silicas chirality transcription from the precursor molecule to the hybrid solid. (Image courtesy of Prof. Joel Morean.)... 

An alternative approach to solid imaging is the CW-NMRI technique, which uses continuous-RF irradiation and detection in the presence of continuously applied, moderately strong gradients. This technique offers a number of advantages compared to other solid imaging techniques ... 

The RF power requirement in CW-NMRI is a factor of 103 to 106 lower compared to the other solid imaging techniques, thus making it practicable to envisage examination of full-size structural components which might prove problematic for conventional pulsed techniques due to excessive RF power requirements. 

Rockwool is a reliable technically oriented provider of insulation materials for the building industry. It is a company mostly involved in business-to-business or B2B marketing, which requires a solid image (see Appendix 15-1). For the Live on Your Roof concept a different image might be required, perhaps that of a life-style designer. It might be better to set up a separate little company under a different name to try the concept out. This new company can more easily make consistent noises on Live on Your Roof than Rockwool as a whole can do. It may have to work in quite different ways. 

K. Zick. STRAFI solids imaging. Technical Report NMR/B353/393, BRUKER Analytische Messtechnik GmbH, D-7512 Rheinstettin, 4/Karlsruhe, 1993. 

Example of an edge dislocation in a metallic solid. [Image created by Greg Sun, University of Massachusetts Boston. Used with permission.]... 

Alfliough a strong effort has been made over the past decades to avoid sexism in education and science, a solid image of science as a masculine job is still pervasive (Calloni, 2009). It seems fliatthe hidden curriculum creates a scientific bias between women and men and perpetuates the transmission of stereotypes, often involuntarily, to students. This kind of process has a negative impact on the lives of both women and men and on society as a whole. 

The difficulties of solid state imaging arise because the solid state linewidth is 1000 times its solution counterpart. Increasing the gradient by three or four orders of magnitude to maintain spatial resolution in solids imaging is a formidable task, and much effort has gone into finding alternatives to such a brute force approach [3]. 

The methodological development and applications of solid-state NMR imaging have been progressing steadily, although a substantial gap between liquid and solid imaging remains owing to the intrinsic difficulties involved with solids. There are a number of excellent reviews " in this area covering the literature published prior to 1995. 

Figure 12.1 Bubble monolayer of varying gas fraction. The bubbles are nearly circular in cross section and form permanent contacts at a critical gas fraction 4>c- Above 4>c/ the system responds elastically to small deformations it is a solid. (Image courtesy M. van Hecke.)...

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