Single-component peaks, overlap

Although these two rate components can be identified in all nerves examined to date, the rates and the precise compositions varies among nerve populations. For example, SCa and SCb are readily resolved as discrete waves moving down optic axons, but differences in rate are smaller in the motor axons of sciatic nerve so the two peaks overlap. Moreover, virtually all tubulin moves as a single peak in SCa in optic axons, but significant amounts of tubulin move at both SCa and SCb rates in sciatic motor axons [32]. In each nerve, certain polypeptides may be used to define the kinetics for a given slow component of axonal transport. For SCa, those signature polypeptides are the NF triplet proteins, while actin, clathrin and calmodulin serve a similar role for SCb. 

As part of this study, random peak overlap was simulated by computergenerated chromatograms in which single-component peaks of random heights were distributed at random positions along the separation coordinate [39]. An example is shown in Figure 6.11. The numbers by each apparent... 

Electron spectroscopy for chemical analysis (ESCA) is a valuable method for studying the oxidation state of the wood surface. The carbon (Is) peak of the ESCA output consists of several overlapping components. Mathematical computer methods can resolve this peak into four component peaks corresponding to carbons with no oxygen substituents (C ), to carbons carrying one single carbon-to-oxygen... 

The quasispherical shape of the C6o molecule suggested that we should analyze the wave functions in terms of their expansion in spherical harmonics. We found that they were dominated by a single / component and we used it to label the lowest peal of the density of states in Fig. 1 is,p,d,... ). The highest peaks also have well-defined angular character, but they have significant splittings and overlaps that will be described in detail elsewhere. Features I and 2 in the spectrum, for example, correspond to tt states with / 5 and 4 angular character, respectively. 

A large number of overlapping peaks Is visually discernible In these simulations, and yet the component number Is considerably less than the peak capacity. Only 105 maxima are observed In the first and 99 maxima In the second simulation. Respective losses of 55 and 61 components result If each maximum Is associated with a single component. These losses justify our earlier assertion that the total component number may be easily underestimated even from a high resolution chromatogram. 

XPS peaks are often broad and show severe overlap like that present in Figure 17.3.6, so curve resolution is widely practiced. Obviously it must be done with care, preferably with foreknowledge of the actual single-component spectra of the substances to which components in mixtures are assigned. 

With constant ion abundance ratios for a peak containing only a single component, changes in the ratios across the peak profile indicate the presence of more than one component in the peak, and provide the basis for completely automated peak-finding and spectral deconvolution algorithms for severely overlapping peaks from unknown mixtures. This obviates the need for complete chromatographic separation and can thus dramatically decrease analysis time (32). 

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