Contents Resonance Condition

Changes In nuclear magnetic resonance measurements of an extensive suite of Australian coals on heating and exposure to pyridine are used to elucidate the molecular conformation of coal macerals Two types of fusible material are Identified In these coals One Is associated with llptlnltes of all ranks and Is typified by fusion commencing at temperatures below 475 K. The other Is associated with vltrlnltes and some Inertlnltes of bituminous coals only and Is characterized by a sharp onset of fusion at temperatures above 625 K. The temperature of onset of fusion Increases with rank for both types The effect of pyridine on the molecular stability of bituminous coals at ambient conditions Is strongly dependent on maceral composition at 86% C and on rank at higher carbon contents ... 

This method relies on the fact that the isotopes of certain atoms have electrons that will flip under certain conditions. This change in state can be detected, and how they are connected can be shown. The H and 13C isotopes are able to produce resonance spectra for polyurethane raw materials and cured samples. ASTM method D4273 details a method to determine the primary hydroxyl content of polyether polyols. 

The use of techniques that focus on a subset of resonances make it possible to do productive NMR experiments on systems that do not have the narrowest possible linewidths, and thus to investigate more challenging proteins or to optimize sample conditions for a particular functional state rather than for the narrowest resonances. However, since the information content of the NMR experiment depends on the number of resolvable resonances, which depends on their linewidths, it is critical to seek conditions that minimize the linewidths while preserving functionality. The membrane protein system of interest will dictate which sample types are possible and which conditions preserve functionality Table 1 documents membrane protein linewidths that have been observed in a variety of sample types including nanocrystals, 2D crystals, detergent micelles, proteoliposomes and nanodisks. 

In this section, we have discussed the condition for tangency using the Melnikov integral and the sudden approximation. The analyses in this section needs to be further developed in the following directions First, the sudden approximation should be improved to take into account the movement of the slow variable, that is, (/, 0). Second, the assumptions Eq. (41) should be removed so that the analyses can be applied to more generic cases. Third, the condition that p is small must be removed so that intersections between resonances of full strength can be analyzed. Fourth, realistic reactions should be analyzed so that the content of this section has more direct relevance to reaction processes. 

Before the adsorption of nitrogen compounds, the silica was exposed in the moistured air to have different water contents. Figure 1 shows the H MAS NMR spectra of silica used in this study. Figure 1(a) is the NMR spectrum of dry silica powder. The narrow peak at 5 = 1.8 ppm is assigned the isolated siianol. It showed general spectrum of dry silica as reported in many studies[9-l 1]. After the exposure in wet condition, the resonance at 3.5 ppm which means the physically adsorbed water was appeared. The water content of silica was increased by exposure in wet air up to 0.11 lg/g.silica. These dry and wet silica were used for adsorption of nitrogen compounds. 

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