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Swelling of cotton in zincoxen solutions of various concentrations was performed for 1 hr at 0°C. The crystallite orientation and the crystallite dimensions of the swollen cotton fibers were determined by x-ray techniques. The swelling in zincoxen improved the orientation and Young's modulus. The relationships between the modulus and (a) the crystallite orientation and (b) the crystallite dimensions were measured, and the correlation was found to be good with the former and poor with the latter.

Apparatus has been constructed for the production of fibres by melt spinning, dry spinning and wet spinning from polymers which may be available only in limited quantities; the operation of the wet spinning line is described. The use of other specialized equipment for a preliminary evaluation of the physical properties of the spun filaments, (e.g. the tensile behaviour at elevated temperatures) is discussed with specific reference to fibres from poly(m-phenylene adamantane-1,3-dicarboxamide). The properties of some experimental high tenacity poly(acrylonitrile) fibres produced by drawing in steam at high draw ratios are also described.

X-ray diffraction patterns from highly oriented fibres of cellulose trinitrate indicate that the molecule crystallizes in a five-fold helical conformation with an axial advance per monomer of 0.508 nm. Computerized molecular model building studies favour a 52 helix, i.e. a right-handed helix with two complete turns of the backbone in the layer line repeat of 2.54 nm. Two possible unit cells, one of which has been proposed previously (Happey, F. J. Text. Inst. 1950, 41, 381), are described and the packing of the chains is discussed.

The degree of swelling of cotton fibre in zincoxen solutions, in relation to the composition of these solutions, has been studied and found to be complex. Optical microscope examination of the cotton fibres in the swelling agent indicated ballooning. The scanning electron microscope was also used to show some morphological details of the swollen fibres. The nature of the swelling process has been deduced from X-ray evidence.

An examination of some physical properties of the α ll and β forms of three synthetic polypeptides (the 1:1 copolymer of DL- β -phenylalanine and DL-leucine, the 1:1 copolymer of DL- β -phenylalanine and L-leucine, and the 1:1:1 copolymer of DL- β -phenylalanine, DL-leucine, and γ -benzyl-DL-glutamate) has been carried out. The two modifications were found to exhibit strikingly different solubilities in non-polar liquids. This result is in agreement with the structures suggested in part I for the α ll and β forms, in which the peptide hydrogen bonds are intra- and inter-chain respectively. The results of a study of the regeneration of the polypeptides from carboxylic acid solutions under various conditions have enabled us to elaborate the mechanism of the action of formic acid given in part I. Further, it has been found possible to effect an α ll → β change solely in the amorphous region of the polymer. The β forms of the two polypeptides have been found to be unstable at high temperatures and to revert to the α ll . The α ll is stable at temperatures up to 280°C, and may readily be obtained in a highly crystalline and oriented form by a suitable heat treatment. X-ray photographs of such specimens show resolution of the polar arcs at 5·2 to 5·3 Å, indicating that the unit cells may have mono- or triclinic symmetry.

Oriented fibres and films of a number of synthetic polypeptides have been prepared, and examined by X-ray diffraction. It is shown that the polypeptides can exist in a folded ($\alpha $) and an extended ($\beta $) configuration. The observations on the $\alpha $ form are consistent with the presence of a twofold screw axis in symmetrical polypeptides, and lead to a value of about 5$\cdot $5 angstrom for the true fibre repeat distance. The fibre period in the copolymers is shown to be greater than 5$\cdot $26 angstrom. It is considered that the X-ray evidence favours a ribbon-like molecule, in agreement with the structure shown in I. The $\beta $ forms of the polypeptides give X-ray diagrams similar to those of $\beta $ proteins, and probably consist of extended polypeptide chains. It is shown that the polypeptides can undergo an $\alpha \rightleftarrows \beta $ transformation similar to that encountered in the fibrous $\alpha $ proteins. The medium from which the peptide is regenerated has a very important influence in determining which form is obtained. Formic acid appears to be unique in producing the $\beta $ modification of polypeptides which swell or dissolve in this liquid. A mechanism for this transformation is suggested. A number of copolymers containing glycine have been examined. These appear to exist mainly in the $\beta $ form. The similarities in the behaviour of synthetic polypeptides and fibrous proteins are discussed.

The problem of dosage integration has presented itself in a variety of ways to different workers in the past. Grimmett1 discussed the subject in relation to radiation protection in the case of a Radium Beam Unit, and a comprehensive survey of the integrated dosage and energy absorption was given by Gray,2 who determined the flow of energy from a radium source. The problem was considered in regard to surface absorption and erythema dose with X rays by Lauritsen,3,4 and a detailed discussion of the general aspects of the subject has been given by Mayneord5 in this journal. A method of treatment of the problem has also been outlined by the present author in Nature,6,7 and the following work gives details of the methods of calculation and the results obtained for beams of X and γ radiation. In this Institution at the present time the underlying principle adopted in the planning of treatment is to give a uniform tumour dose between 4000r and 6000r. In deep-seated lesions this can only be achieved by using a mu...

It has been shown that the outer root sheath—inner root sheath boundary is not as smooth as was previously thought and that the Flugelzellen of Huxley's layer contain trichohyalin granules. Also, the β-keratose fraction obtained from oxidized wool and hair has been shown to be of dual origin—partly intra- and partly intercellular. Finally, a suggestion is put forward concerning the phosphorus content of wool. The presence of fibrillar material in the keratinizing hair cuticle has been demonstrated for the first time, and this makes possible a restatement of the concepts of fibrous protein formation in the hair follicle.

Being a report of the meeting of the X-ray analysis group of the Institute of Physics held at the university of leeds on the 25th November 1944.

A brief review of an experimental study of the effects of variations in combing procedure on the physical properties of worsted yarns is given. Because of the results obtained, a study was made of the fibre-length distribution in the uncombed and combed materials. A discussion of the findings concludes the paper.

It has now become of interest to study the structure of the synthetic polypeptides as they form simple models to use in the study of the more complex protein structure. In a very wide field, this has been done from the point of view of the helical and extended forms of the α and β polypeptide structures, and many polypeptide configurations have been characterized. In this paper, studies are made of the α, β and ω forms of the poly-β-benzyl- l -aspartates and their structural transformations on heating, including the types of energy transforms (endothermic or exothermic) accompanying these modifications. These latter changes have also been followed by X-ray and i.r. studies which have enabled us to characterize the forms unequivocally. In one of the poly- β-benzyl- l -aspartates, the transformation on heating has been shown to be α → ω → β; α → ω transformation is exothermic and the ω → β endothermic in character.

The structure of gels formed from solutions of silk fibroin has been observed by electron microscopy. The gels consist of fibrils, and possible methods of formation of these fibrils are suggested.

A description is given of the details of construction and the method of operation of the Radium Beam unit which has been installed at the Radium Centre in Sheffield. The bomb is a mass unit capable of carrying a maximum content of 6.2 g. of radium in a light, flexible shuttle. This is transferred pneumatically from the safe to the bomb and vice versa. An automatic signalling gear and clock is incorporated in the apparatus. The bomb may be raised vertically by means of an electric motor, and can rotate round vertical and horizontal axes. A vertical traverse of 3 ft. is possible for the bomb and an overwind mechanism is brought into action in the highest and lowest positions of the bomb head.

Results obtained by physical methods of examination, particularly X-ray diffraction, polarizing and electron microscopy and more recently differential thermal analysis, are reviewed. The different structures of the elastic wall of the disc (annulus fibrosus) and the gel-like centre of the disc (nucleus pulposus) are described in relation to their functions. An important component of aged nucleus pulposus is a substance giving an X-ray diffraction spacing of 4·7 A, presumably a denatured protein in the β-form, but its origin is still obscure. The value of differential thermal analysis in the study of collagen of the disc and other connective tissues is illustrated.

As the temperature of solid poly(β-benzyl-L-aspartate) (PBLA), (CO.NH.CH.-CH2COOCH2C6H5)n, in the α-helieal form is raised from −150 °C, tlie line width and second moment of the proton magnetic resonance (PMR) signal decrease in stages until the conformational transition to the ω-helix occurs at about 90 °C. A similar temperature dependence of the PMR parameters is observed as the transformed polymer is cooled. Below −100°C (where the lattice is presumed to be rigid), the measured second moments are 9.5 Oe2 and 10.7 Oe2 for the α and ω forms, respectively. Second moments, calculated from the Van Vleck formula for the rigid lattice and also estimated for possible motional cases in which the polymer is taken to be in the ω form, are compared with the PMH data. By combination with the results of X-ray diffraction and infrared spectroscopic measurements, a tentative explanation can be made of the types of motion occurring in PBLA.

THE shrinkage temperature of the collagen of dura mater or fascia lata has been shown to increase with age1. Shrinkage of these tissues and tendon or skin can be watched and a micro-melting point apparatus was used for their determinations. The transition can also be detected from force–temperature curves, and use of this method has shown an increase of shrinkage temperature with age for tendon collagen, except when measurements were made at pH less than 4.5. If the fibres were maintained at constant length during the heating, the shrinkage temperature showed little variation with age (or pH)2–4.

Publisher Summary This chapter discusses the structure and function of the human intervertebral disk and the three major components: (1) the bony end plates, (2) the gel structure of the nucleus pulposus, and (3) the elastic wall of the anulus fibrosus. It describes idealized disk mechanism and the factors associated with the elastic behavior of collagen in the wall of the disc. On the assumption that the nucleus pulposus behaves as an incompressible gel, the basic elasticity of the disk can be understood. From the end plates of the vertebral bodies, the pressure is transmitted to the nucleus. If there is no change in the volume of gel, then a uniform pressure is developed on the disk wall. The crystalline component of the wall has a high aqueous content, and the sheets of collagen fibrils can slide over one another without opening the structure appreciably. The cross-striation in the anulus has the merit of producing a tissue system with the strength per unit thickness comparable in all directions of strain. However, it must be realized that any variations in the aqueous content of the crystalline lattice must have an effect on the ultimate strength of the individual sheets of collagen. Any differences in wall thickness must play a major part in determining the extension of the wall even if a uniform pressure is applied to the inner collagen sheets.

There is evidence that degradation of the proteoglycans in the intervertebral disc occurs on aging and similar changes appear to be associated with herniation or prolapse (Davidson and Woodhall, 1959; Lyons et al., 1964, 1966). It is not known whether a defect in biosynthesis or increased catabolism is responsible for the deterioration. Human discs obtained at surgery have been shown to contain β-N-acetylglucos-aminidase and β-glucuronidase (Platt, 1970), which were probably derived from lysosomes but this was not proved.

THE nucleus pulposus of the normal human intervertebral disk consists of collagen fibrils dispersed in a gel of polysaccharide and protein complexes. During ageing collagen fibrils are deposited as a matrix showing increasing orientation with age as seen from X-ray diffraction investigations1. In the case of specimens of more than 70 years of age, the normal photograph shows with the diagram of oriented collagen a clearly defined ring of spacing 4.7 A., which is similar to that associated with a denatured β-protein1 The presence of other components in the disk, for example, calcium phosphate, etc., will be discussed in a later publication. It was postulated from consideration of earlier work1 that the soluble protein molecules normally found in a folded form in the nucleus had unfolded and formed a hydrogen-bonded lattice which gave rise to this spacing.

IN the past few years considerable progress has been made in the regeneration of certain protein fibres from solution ; in particular, casein1 and peanut globulin2 have been spun with considerable success. Hewitt and Coleman3 have dissolved and respun silk, Lundgren4 and his co-workers have made fibres from dissolved chicken feathers, and one of us (R. L. W.) has described the regeneration of a protein from a mixture of casein and soluble keratin5. In the following, a short description is given of the regeneration of wool keratin fibres from solution. This material was made by the method previously de scribed by Wormell5, and its X-ray photograph is reproduced herewith. It can be seen from this diagram that the keratin molecule is in the β or fully extended form, and there is no evidence of the presence of the typical α-fold of the original wool molecule.

No detailed investigation of the mucopolysaccharide component of nuclei pulposi has been reported, but the combined results of several groups of workers1–3 suggest that more than one type of mucopolysaccharide is present. The presence of at least three mucopolysaccharides in human nuclei pulposi is now reported, together with a simple method for their partial separation.

A study is being made of the use of differential thermal analysis to detect heat-induced structural changes in certain polypeptides in the solid state. Thermograms are presented showing the transition of poly-β-benzyl-L-aspartate from the a to the β form both directly and by way of the ϕ conformation, and of the α → β transition in other polyaspartate esters. The analysis of such thermograms should give useful information upon the relative stabilities, heats of transition and the mechanisms by which the observed transitions proceed.

A cellulose-protein complex is reported as a normal although minor constituent of mammalian connective tissue; higher concentrations have been observed in certain pathological human skin conditions. Experiments on the degradation of collagen by treatment with alkaline buffers have afforded histochemical evidence for the production of highly anisotropic fibres. Chemical and physical studies show that these fibres consist of a protein-polysaccharide complex, the polysaccharide fraction of which is indistinguishable from native cellulose, arranged in helical form round a protein template. The question of fibrogenesis is discussed in the light of synthetic studies whereby anisotropic fibres having similar properties to those of native mammalian cellulose fibres can be obtained by the interaction of gelatin, chondroitin sulphate and calcium ions.

CONTINUING our work on the structure of synthetic polypeptides1,2 we have recently spun fibres of a number of these products. The following is a preliminary review of the results of an X-ray examination of two—a copolymer of L-glutamic γ methyl ester with DL-β-phenylalanine (A), and poly DL-β-phenyl-alanine (B). fig. 1 and 2 are X-ray photographs of the former in disoriented and oriented states respectively ; Fig. 3 is a photograph of oriented fibre B. These diagrams show that both polymers have very similar structures. In A, the repeat along the fibre axis is 5·26 A., and it is possible that the intense equatorial reflexion can be resolved into two spacings of 11·7 A. and 11·2 A. ; the angular dispersion of the former arc is much greater in this particular specimen. The 11·7 A. and 11·2 A. spacings, therefore, appear to orient to different extents on stretching. In the powder diagram of the fibre, Fig. 1, the spacings are not resolved, and give a mean of 11·4 A. In B, the repeat along the fibre axis is 5·28 A., and the equatorial arc may perhaps again be resolved into a doublet of spacings—12·8 A. and 11·7 A. These two overlapping arcs again show differences in angular dispersion, that at 12·8 A. being the greater, but this is not so marked as in the former case.

THE nucleus pulposus of normal human intervertebral disk contains the two acidic mucopolysaccharides, chondroitin sulphate and keratosulphate1–3. During ageing an increase of collagen occurs4 leading to a decreased ratio of mucopolysaccharide to collagen, although the absolute amount of mucopolysaccharide remains constant4.

The application of differential thermal analysis as a tool for the identification and characterization of structural features in fibrous proteins has been studied. The influence of experimental variables is considered, and the effects of such factors as sample preparation and atmosphere control on the resultant differential thermographs have been examined. Some of the differences between, and possible assignments for, the differential thermograph peaks, particularly of keratin fibres, are considered. With these fibres, a doublet is found in the 200° to 250°C region, and it is suggested that this may be related to the melting of the α-keratin associated with the p- and o-cortical structures, respectively. Evidence is presented for a glass transition at about 165°C in the amorphous regions of keratin fibres. The detection and characterization of polyamide finishes on wool is demonstrated.

In attempting to explain the different physical characteristics of collagen in various tissues, a number of possibilities have been proposed. These include variations in glycosaminoglycans, more firmly associated “structural glycoproteins” (Robert and Robert, 1967) and collagen hexose contents (Spiro, 1969; Grant et al., 1969). The location of the hexose on specific hydroxylysine residues may hinder the formation of intermolecular cross-links (Morgan et al.. 1970), possibly imposing a limit on fibril diameter. Analyses of different layers of bovine skin indicate that coarser fibres are characterised by an increased dermatan sulfate: hyaluronic acid ratio (Hoffman et al., 1957). This arises mainly from a deficiency in hyaluronic acid because, contrary to previous statements, the dermatan sulfate remains approximately constant (Pearson, 1970). Keratan sulfate may be implicated in the formation of very thin fibrils found in more transparent tissues like cornea and nucleus pulposus.

Meyer and Rapport1 described the isolation from hyaline cartilage of two chondroitin sulphates, A and C. The only differences so far reported2 between these are in the specific optical rotation and alcohol solubility of their calcium, salts. Orr3 found that chondroitin sulphate from cartilage gives an infra-red spectrum which suggests that the product is a mixture of two isomers, A and B (see below). By counter-current electrophoresis he was able to obtain the faster component of this mixture, which exhibited in the 700–1,000 cm.−1 region 3 bands, at 928, 855 and 725 cm.−1, respectively, and was called the A isomer. The B isomer, on the other hand, was isolated alone in a well-defined form from the nucleus pulposus and showed two bands at 825 and 775 cm.−1, respectively. Meyer et al. 2 pointed out the similarity between Orr's B isomer and chondroitin sulphate C. On the other hand, both A types show the same optical rotation and origin. The following results seem to give a different picture of the mucopolysaccharides of cartilage and nucleus pulposus.

Preliminary X-ray observations on the crystalline changes produced in the metallic and oxide films of copper during the activation process appear to supplement the results of Garner and Stone1. The accompanying X-ray diagrams were obtained from narrow slivers of rolled copper sheet 0·0025 in. thick, using copper Kα radiation filtered through nickel foil to remove the β component. A flat quadrant plate spectrometer was used for the comparative X-ray measurements.

IN a discussion on the possibility of producing a regenerated keratin fibre, Mercer1 claims to have retained the α-form of the molecule in wool reconstituted from solution. This is a matter of some interest, as the yarns produced by Dr. R. L. Wormell2 and myself show no evidence of the α-keratin structure even in orientated fibres. During the past few months, highly orientated specimens of casein yarn have been made3 which may throw some light on Mercer's results, especially with reference to the type of solution from which fibres are drawn containing an α-keratin phase. Fig. 1 is an X-ray photograph of a Ferretti-type casein fibre which shows little or no obvious orientation by X-rays. Fig. 2 is an X-ray photograph of highly orientated casein which is, in the main, made up of reflexions from a two-phase system. First there is the X-ray photograph of a normal β-protein type of fibre comprising an axial repeat of 3·25 A., a backbone spacing of 4·65 A., and a side-chain spacing of approximately 10·5 A. Superimposed on this diagram, however, there is a strong polar arc of 4·65 A., which is most probably indicative of a protein phase containing a crystalline cross β-configuration of the molecule.