Ultrasonic measurements of the elastic stiffness constants of oriented polyethylene

High density polyethylene (Rigidex 9), a high density copolymer of polyethylene and poly(butene-1) (Rigidex 2000), and low density polyethylene (Alkathene WJG 11) were oriented by hot drawing. The crystalline texture, as determined by wide- and low-angle X-ray diffraction, was a highly oriented chain axis in the draw direction with random orientation transversely and with lamellae surfaces perpendicular to the draw direction. Elastic stiffness constants were measured by a contact-probe ultrasonic pulse technique at 2.5 MHz both before and after annealing in a temperature range which did not significantly alter the crystalline texture. Assuming orthorhombic symmetry the nine stiffness constants of Rigidex 2000 and the three longitudinal and three shear stiffness constants of Rigidex 9 were measured after drawing and after subsequent annealing. Only the longitudinal constants of Alkathene were measured, as shear waves could not be transmitted. The longitudinal stiffness in the draw direction was markedly affected by drawing and by annealing, while the crystalline texture remained substantially unchanged; by comparison the other stiffness constants showed little change. Drawn Rigidex 9 reached a tensile modulus in the draw direction of 69 GPa. The results are compared with ‘static’ and low frequency measurements reported in the literature.     

Villous papilloma of the rectum presenting as infective gastro-enteritis

Three elderly patients have recently been admitted as emergencies to the Infection Unit of the Aberdeen Hospitals as presumed cases of infective gastro-enteritis. Investigation revealed the presence of a villous papilloma of the rectum in each case.     

A study on the orientation effects in polyethylene in the light of crystalline texture

Special sample types established and characterised in Parts 1 and 2 [1,2] were examined systematically under different modes of external deformation at constant temperatures. The structural changes recorded by means of wide- and low-angle X-ray patterns fully substantiated the bodily rotation of the otherwise unaltered crystallites in accordance with the interlamellar slip mechanism postulated in Parts 1 and 2, both in tension and under two modes of compression. Dimensional changes, however, were significantly in excess of those expected from the rotation of crystallites, but were uniquely correlated with this relation in the different samples under different conditions of deformation. This points to a unique structural and mechanistic interrelation between the crystallites and more compliant amorphous regions. As the X-ray long periods were unaffected by the deformation, the more extensible material cannot be identical to that associated with the lamellar periodicity, a fact which points to a previously unsuspected superlamellar regularity in the texture. A simple structural suggestion is made.     

Eimeria maxima: a comparison of two laboratory strains with a fresh isolate

Oocysts of the Weybridge and Houghton strains of Eimeria maxima and a fresh field isolate were similar and measured on average 30-9 X 22-4 mum. The Weybridge strain and the field isolate produced similar pathogenic effects in 6-week-old chickens, high doses causing 50-80% mortality and severe weight loss. The Houghton strain was slightly less pathogenic and few birds died but more oocysts were produced. With each strain, a single dose gave complete immunity to a light challenge with the homologous strain. Two or 3 immunizing doses gave complete immunity to a heavy homologous challenge but were not sufficient to protect against heterologous challenge.     

Dermal and glomerular deposition of IgA in anaphylactoid purpura

During the period of acute anaphylactoid purpura, skin biopsies were performed on 14 patients with purpuric and nonpurpuric skin. In addition, four patients had renal biopsies. Examination of the tissue by immunofluorescence to anti-human immunoglobulins IgG, IgA, IgM, and IgE, fibrin/fibrinogen, complement Clq, C4, and C3 demonstrated predominant IgA, C3, fibrin/fibrinogen in the purpuric skin and glomerulus, without Clq and C4. These immunohistochemical findings are characteristic of anaphylactoid purpura and suggest that IgA is involved in the pathogenesis of anaphylactoid purpura and may operate through the alternate pathway of the complement system.     

A method for monitoring uterine activity in induced labour

A system for the quantitative assessment of uterine activity during an oxytocin-induced labour has been developed. This has been achieved using relatively simple analogue techniques and can easily be used in the labour ward alongside existing monitoring equipment. Initial results indicate that a plateau of uterine activity can be easily recognised from the display and maintained at oxytocin dosage levels below those that might normally be used.