Hard fibres

These fibres, obtained from the leaves of agaves, Manila hemp, New Zealand flax and various bromeliads, are important in the manufacture of cordage and of coarse textiles.     

Brush-making fibres

Fibres from palm leaf-bases of the tropics clean our streets and fibres from agave plants of Mexico clean our clothes, while fibres from a variety of other plants enter into the manufacture of a variety of brushes for specialized industrial uses.     

Keratin-like fibres in the hemichordate Rhabdopleura compacta

Summary The coenecium of Rhabdopleura is a tube that surrounds the zooid. It is secreted by the cephalic shield of the zooid and contains three sorts of fibres in an electron lucent matrix. One of the fibre types contains a double helix of fine fibrils. Preliminary histochemical investigations suggest that the fibres may be keratinous.I wish to thank Professor J. Z. Young F.R.S. for enthusiastic advice and encouragement. Dr. R. Bellairs generously provided the facilities for electron microscopy. Dr. A. J. Southward and Dr. A. Stebbing of the Plymouth Marine Biological Laboratory generously gave of their time and expertise, and helped me to obtain and identify the specimens. Dr. R. Willis and Miss Marion Dennison assisted with the preliminary stereoscopic electron microscopy. Mr. R. Moss gave excellent technical and photographic assistance.     

Biotransformations in synthetic fibres

Recent studies clearly indicate that the modification of synthetic polymers with enzymes is an environmentally friendly alternative to traditional chemical methods requiring harsh conditions. Some work already performed on polyamide 6.6 (nylon 6.6), polyethyleneterephthalate (PET) and polyacrylonitrile (PAN) revealed that surface functionalization of these materials is a key requirement for an extensive range of applications, such as textiles, electronics, biomedical field and others. Research performed on PET with lipases, cutinases and other esterases has previously been reported, whilst enzymatic treatment of PAN with nitrilases and cutinase has also been the subject of study. However, at present, few studies have been done on nylon fabrics, mainly with esterases and proteases. This work is intended as a brief review of research in the area of biocatalytic functionalization of synthetic fibres, with a special focus on work recently performed by our research group with cutinase from Fusarium solani pisi.     

Neurophysin and the neurosecretory fibres of the sheep infundibulum

Summary A cross-species reactive antiserum was used to study the cellular localization of neurophysin in the sheep hypothalamus and neurohypophysis. The immunofluorescent technique was used to follow the neurosecretory fibres emanating from the magnocellular nuclei to the lower infundibular stem. It was confirmed that neurophysin was present in both the internal and external zone of the infundibulum.This work was supported by a research grant from the New Zealand Medical Research Council.     

On the capacity current in myelinated nerve fibres

Different equivalent circuits are presented to describe the capacity current, Ic, of potential-clamped Ranvier nodes. The corresponding transfer functions are discussed in examining the influence of the involved parameters on size and time course of Ic. The following results were obtained: i. The duration and the amplitude of Ic increased with increasing membrane capacity. ii. The amplitude of Ic increased with increasing gain or decreasing time constant of the clamp amplifier while its duration was shortened. iii. Similar effects were seen with decreasing resistance in series with the nodal membrane. iv. Qualitatively identical but stronger effects were seen with increasing bandwidth of the current measuring internode. Measurements were carried out under experimental conditions close to the calculated ones. They resembled the calculated curves satisfactorily.     

The orientation of the alpha-helices in alpha-keratin fibres

Considerable physical evidence has been accumulated in support of the polarity of alpha-keratin fibres and is summarised here. Dielectric loss and dielectric dipole movement in dry intact fibres as they undergo thermal transition above 200 degrees C show alpha-keratin to be a polar structure. X-ray diffraction has shown that this transition corresponds to the randomisation of the organised alpha-helical structure resulting in the loss of polarity of the fibre. The piezoelectric properties of alpha-keratin can only be explained if its alpha-helical dipoles in the ordered structure alpha-keratin are synergistically aligned in the axial direction. If the alpha-helical units of the IFs of alpha-keratin fibre were in an anti-parallel conformation then dry alpha-keratin would show no polarity. FTIR measurements on alpha-keratin fibres extended in water at 21 and 95 degrees C explain the formation of anti-parallel beta-structures when fibres are extended in steam. Contrary to in vitro experimental data there is clear evidence that native alpha-keratin fibres are polar structures with the alpha-helices aligned in a parallel conformation.     

The staining of elastic fibres with Direct Blue 152. A general hypothesis for the staining of elastic fibres

Summary Elastic fibres may be stained by a number of dyes, e.g. Direct Blue 1 (C.I. 24410), Direct Blue 10 (C.I. 24340), Direct Blue 15 (C.I. 24400), Direct Blue 152 (C.I. 24366) and Direct Violet 37 (C.I. 24370). A convenient method using Direct Blue 152 has been developed which is specific for elastic fibres. The method is simple and allows the demonstration of other connective tissue fibres. Staining of elastic fibres is unimpaired by numerous blocking procedures or by changes in dyebath pH. These properties are shared by several standard elastic fibre stains.As the Direct dyes and several of the standard elastic fibre stains possess numerous aromatic rings a wide range of dyes containing varying numbers of aromatic rings were examined for ability to stain elastic fibres. No association was observed between the ability to stain elastic fibres and dye class, formal charge or the presence of hydrogen bonding groups. Staining was, however, definitely associated with the presence in the dye molecule of 5 or more aromatic rings. This suggested that van der Waals forces of attraction may be responsible for elastic fibre staining both by Direct dyes and the standard elastic fibre stains. Staining of elastic fibres as a side-effect in many procedures is similarly explicable.     

Characterization of lignocellulosic curaua fibres

Curaua fibres have specific mechanical properties similar to inorganic fibres and are an important renewable raw material. Milled curaua fibres, submitted to different treatments, were characterized by mechanical and thermal properties, moisture content, water absorption, surface morphology, FTIR spectroscopy, density and X-ray diffraction. Except for moisture content and mechanical properties, no other significant changes were observed after the treatments. The treated fibres also show an increase of surface roughness.