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While many investigators have examined electromagnetic and magnetohydrodynamics phenomena in electromagnetic casting (EMC) of aluminum, there appears to be no published work on heat transport and solidification in such casters. This two-part series is an attempt to remedy this deficiency. The first part describes two experimental campaigns, carried out on a pilot-scale electromagnetic caster at Reynolds Metals Company, in which sacrificial thermocouples were used to obtain many data on temperature distributions within the aluminum of a pilot-scale caster and thereby to obtain the shape of the liquid metal pool (sump). The data reveal a strong dependence of temperature distribution and sump depth on casting speed but a relatively weak dependence on the flow rate of the quenching water striking the outside of the ingot.

In this second article of a two-part series, a mathematical model for heat transport and solidification of aluminum in electromagnetic casting is developed. The model is a three-dimensional one but involves a simplified treatment of convective heat transport in the liquid metal pool. Heat conduction in the solid was thought to play a dominant role in heat transport, and the thermal properties of the two alloys used in measurements reported in Part I (AA 5182 and 3104) were measured independently for input to the model. Heat transfer into the water sprays impacting the sides of the ingot was approximated using a heat-transfer coefficient from direct chill casting; because this heat-transfer step appears not to be rate determining for solidification and cooling of most of the ingot, there is little inaccuracy involved in this approximation. Joule heating was incorporated into some of the computations, which were carried out using the finite element software FIDAP. There was good agreement between the computed results and extensive thermocouple measurements (reported in Part I) made on a pilot-scale caster at Reynolds Metals Company (Richmond, VA).

Recent evidence implicates fiber type proportions as playing a role in meat eating quality, and in pigs it has been suggested that the slow oxidative fibers contribute to both juiciness and tenderness. The fiber distribution in pigs is different from that found in most other species, in which the various types of skeletal muscle fiber are distributed in a "checkerboard" pattern, because in pigs the slow oxidative fibers have a clustered distribution. The initial processes leading to fiber clustering are likely to occur during myogenesis, but the precise mechanistic aetiology of this patterning and whether the slow oxidative fiber clusters occur in a random or ordered fashion is unknown. In the present study longissimus thoracis muscle from Large White crossbred pigs was sampled at the 10th rib, 48 h postmortem. Transverse cryo-sections were cut and histochemically stained to allow the identification of the main muscle fiber types: slow oxidative, fast glycolytic, and fast oxidative glycolytic. Images of the sections were captured and analyzed using point processes and Voronoi Tesselations to examine the randomness and spatial distribution of the clusters of slow oxidative fibers found in pig longissimus thoracis muscle. The results showed that an assumption of complete spatial randomness can be rejected and that a mathematical model incorporating a minimum distance of 1.7 to 2.0 microm between cluster centers produced fiber patterns similar to those observed in the original transverse sections of the muscle. In addition, if it assumed that the central fiber in each cluster is derived from primary myoblast progenitors, these results suggest that there may be some degree of repulsion between the primary fibers during the initial stages of cluster formation. The mechanistic basis of such repulsion is not clear, but it is speculated that secreted factors, such as sonic hedgehog or myostatin may play a role.

Women with coronary artery disease (CAD) have a prognosis at least as bad and possibly worse than men. Differences in classical risk factors do not fully account for these findings and there is evidence that circulating levels of haemostatic factors may predict CAD risk. In this study sex differences in haemostatic risk factors were examined in relation to coronary stenosis. 609 (420 men, 69%) subjects admitted for coronary angiography for suspected CAD were recruited. Levels of Factor VII:C (FVII:C), fibrinogen, plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF) were estimated in 296 subjects from one centre. Of these, women (n = 107) had higher levels of FVII:C (134% vs 117%, p0.0005), and fibrinogen (3.4 g/l vs 3.2 g/l p = 0.01) than men (n = 189) and these differences remained after adjusting for other covariates. In subjects with angiographically significant atheroma these differences in haemostatic factors (n = 50 for women vs n = 147 for men) were exaggerated, (FVII:C 139% vs 117, p0.0001, fibrinogen 3.7 g/l vs 3.3 g/l p = 0.003), PAI-1 (26.2 ng/ml vs 19.7 ng/ml, p = 0.02) with a trend towards higher levels of vWF in the women. Women with significant atheroma at angiography (n = 50) had higher levels of PAI-1 (25.0 ng/ml vs 13.4 ng/ml p0.0001) and vWF (1.25 IU/ml vs 1.06 IU/ml, p = 0.02) and a trend towards higher levels of both fibrinogen and FVII:C than women with normal or in significant coronary vessel disease (n = 57). Elevated circulating levels of PAI-1, vWF, fibrinogen and FVII:C in women with angiographically proven CAD may contribute to an adverse cardiovascular risk factor profile and the poorer prognosis in females than male patients with proven coronary artery disease.

We demonstrate the application of ultramicrotome techniques for the preparation of thin semiconductor interfaces in cross-section, for analysis by electron beam techniques. This is of significance for semiconductor device technology, since a specific area on a particular device may be examined in cross-section. High-resolution transmission electron microscopy studies of twinned structures at the interface of a 1.2 μm metal-organic chemical vapour deposited HgCdTe epilayer on {100} GaAs are reported. {100} epitaxial growth starts to dominate about 40 nm from the interface, and continues to the top surface of the epilayer. Energy-dispersive X-ray analysis shows that the mercury concentration within the epilayer increases as the interface is approached. No evidence of diffusion into the GaAs substrate was obtained.

We report on the use of high resolution electron microscopy and optical processing techniques to study defects in solid inert gas precipitates (bubbles) formed by ion implantation into aluminium. Faceted precipitates, of the order of 5 run in length and epitaxial with the aluminium, in some cases exhibit a high degree of crystalline perfection but in others departure from the regular atomic arrangement is evident in the lattice images. Optical processing techniques have been applied to enhance the lattice images and in some cases to colour encode the aluminium and inert gas spacings present in the micrograph, with the aim of indentifying specific defect structures in the inert gas solid. We demonstrate that the solid “bubble”, formed in a metal by ion implantation, provides a means of studying defects in a simple insulator, the rare gas solid.

The effects of operating gratings with non-zero constant angular deviations are discussed. The results show that gratings having triangular groove profiles are far less sensitive to the deleterious effects of angular deviation than are holographic gratings. In the case of ruled gratings, angular deviation can often provide a useful reduction in the undesirable effects of anomalies. Ruled gratings have often been utilized in a combination of first and higher orders, so as to extend their spectral range. This has motivated the comprehensive studies reported of the second and third order blazes of ruled gratings. It is shown that the higher order blazes of holographic gratings are both narrower and weaker than those of comparable triangular profile gratings. Thus, holographic gratings are less suited to use with a plurality of orders.