Hand-sectioning

The magnitude of the shearing force and the moment can be determined from the conditions of static equilibrium of the beam section. Thus, for the cut shown in Figure 2-29b, the shear force and the moment on the left-hand section are... 

The copper EXAFS of the ruthenium-copper clusters might be expected to differ substantially from the copper EXAFS of a copper on silica catalyst, since the copper atoms have very different environments. This expectation is indeed borne out by experiment, as shown in Figure 2 by the plots of the function K x(K) vs. K at 100 K for the extended fine structure beyond the copper K edge for the ruthenium-copper catalyst and a copper on silica reference catalyst ( ). The difference is also evident from the Fourier transforms and first coordination shell inverse transforms in the middle and right-hand sections of Figure 2. The inverse transforms were taken over the range of distances 1.7 to 3.1A to isolate the contribution to EXAFS arising from the first coordination shell of metal atoms about a copper absorber atom. This shell consists of copper atoms alone in the copper catalyst and of both copper and ruthenium atoms in the ruthenium-copper catalyst. 

In the right-hand section, N-ethylation of the aniline nitrogen was optimal, while shifting the methyl to the 4-position increased activity. This, combined with fluorination at the m-position, afforded (23b) as the most potent compound of this series. Since the pharmacokinetic properties of (23b) were not disclosed, it is not clear if manipulation of the hit compound led, apart from an increase in potency, to a corresponding improvement of the pharmacological profile. 

If the sections are not washed, they need to be dried well right after excision. On the other hand, sections that are washed need to be dried well before the matrix application. Not drying them sufficiently may cause the samples to peel off in the vacuum chamber of the mass spectrometer. 

In some instances, failure to include the nature of the specimen will not be contrary to the intent of the regulations. For example, a microscopic slide that contains liver tissue need not have liver written on the slide since the end user, the diagnosing pathologist, will not need the label to identify the tissue as liver. On the other hand, sections of tumor from... 

Fig. 16. Delayed emission spectra of 10 3M phenanthrene in ethanol.33 The left-hand sections of the spectra (delayed fluorescence) all were recorded at a sensitivity approximately 1000 times greater than that used for curve (1) (normal fluorescence). The right hand sections of the curves (phosphorescence) were recorded at the following sensitivities (2) —107° at 60X (3)...

A good description of hand sectioning is given in O Brien and McCully (1981). 

The lower curve which uses the lower scale is an enlargement of the left-hand section of the upper curve... 

FIG. 18. As chemical shift chart the left-hand section shows the region of alkyl and aryl arsonium salts. (166) A positive sign indicates relative deshielding. 

Free-hand Sectioning.—Free-hand sections are usually satisfactory for the general examination of roots, stems, leaves, barks and many fruits and seeds. Material which is fresh may be sectioned at once, but dry material should be well soaked in warm water before using. Very hard material like heartwoods, the shells of nuts and seeds, may be softened in solution of caustic potash or ammonia water and then washed free of alkali before sectioning. 

Whenever material is unsuited for free hand sectioning and will not give good results when imbedded in paraffine on account of size, hardness, or brittleness, celloidin may be resorted to as an imbedding medium. 

Fig. 2.39 Dimensions for solidification on the outside (left hand section) and inside (right hand section) of a tube or a hollow sphere...

Plots of the function K xUO vs. K at 100°K for the extended fine structure beyond the osmium edge for pure metallic osmium, and for the osmium-copper clusters in the catalyst containing 2 wt% Os and 0.66 wt% Cu, are shown in the left-hand sections of Figure 4.13. The associated Fourier transforms of the functions are shown in the right-hand sections of the figure. As previously noted, the Fourier transform yields the function n(R), the peaks of which are displaced from the true interatomic distances because of the phase shifts. Similar plots for the extended fine structure beyond the copper K edge for pure metallic copper and for the osmium-copper catalyst are given in our 1981 paper (32). 

In the upper half of the figure, the left-hand section compares the resonance for a silica-supported osmium catalyst containing 1 wt% osmium with that for pure metallic osmium. The magnitude of the resonance is higher for the osmium dispersed on the support, the extent of increase being indicated by the difference spectrum in the lower left-hand section of the figure. This effect is similar to the results we reported for iridium and platinum dispersed on an alumina support (39). 

The functions /C3Xi (X) shown in the right-hand sections of Figure 4.26... 

The two upper sections of Figure 4.29 show the normalized fitting error as a function of Rt, for the physical mixture and the alloy. The two lower sections show the values obtained for the distance Rn for various values for Rlr. The left-hand sections of the figure refer to the physical mixture, which was diluted with alumina to give a sample containing 10 wt% each of platinum and iridium. The right-hand sections refer to the bulk alloy, which contained 58 wt% platinum and 42 wt% iridium. 

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