RESUMO
ABSTRACT: Foam-forming has in the past predominantly been used to create two-dimensional sheet-like fibrous materials. Allowing the foam to drain freely and decay under gravity, rather than applying a vacuum to remove it rapidly, we can produce lightweight three-dimensional fibrous structures from cellulose fibres, of potential use for thermal and acoustic insulation. µ CT scanning of the fibrous materials enable us to determine both void size distributions and also distributions of fibre orientations. Through image analysis and uniaxial compression testing, we find that the orientation of the fibres, rather than the size of the voids, determine the compressive strength of the material. The fibrous samples display a layering of the fibres perpendicular to the direction of drainage of the precursor liquid foam. This leads to an anisotropy of the compressive behaviour of the samples. Varying the initial liquid fraction of the foam allows for tuning of the compressive strength. We show an increase in over seven times can be achieved for samples of the same density (13 kg.m-3).
RESUMO
Three hundred sixty-seven carotid endarterectomies were monitored using routine electroencephalographic (EEG) techniques. In 9.8%, changes in the EEG followed clamping of the internal carotid artery and could roughly be grouped into 6 patterns. The most common (47%) was rapid unilateral or bilateral attenuation of background anesthetic-induced fast EEG activity. Conclusions drawn from studies of the 9 patients who had immediate postoperative neurological deficits of varying degrees are presented as they illustrate monitoring techniques that are useful for early recognition of cerebral ischemia. Thirty-five patients were monitored with both routine and computerized techniques--the latter proved more useful than the former on all counts.
