Microfibrils definition

The most important discovery in recent years has been the clear evidence obtained by Filshie and Rogers (1961) of an organized protofibrillar substructure within the microfibril. This substructure is illustrated in Fig. 13 together with an example of the less definite evidence for longitudinal substructure. As far as is known the size and substructure of the microfibril seem to be a constant feature of a-keratins from a variety of animals. Thus the microfibril may be regarded as the fibrillar unit of structure, although it is to be anticipated that some species-to-species variation in detail will occur in view of the known variability in amino acid composition (Section III,R,1). 

Model Fit or Direct Evaluation Similar to the ID case we can now fit a model to the projected intensity or to the CLD. What we get in this case is the needle-diameter distribution of the microfibrils. Nevertheless, there are two other possibilities to direetly evaluate the data. We consider polydispersity by allowing for varying hard-disc diameter. If we assume that the shape of each disc is circular, the CLD of an uncorrelated hard-disc fluid is the Mellin convolution of the intrinsic chord distribution, gc ri2), of an ideal disc of diameter 1 and the diameter distribution, ho (D) which characterizes the structure. The definition of theMehin convolution (Titchmarsh [202], S. 53 Marichev [203] [86], S. 304) is... 

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