Model experiments illustrating fibre pull-out

Pull-out of a rigid fibre from a solid matrix has been studied in a model of a composite material using transparent media to display the fracture. Solidified gelatine solution was used to model an elastic-plastic matrix and silicone rubber used to represent a brittle elastic material. The conditions dictating both brittle and plastic failure in the model have been presented theoretically and supported by experimental observations. In addition, a novel type of failure, where bubble cracks propagated between fibre and matrix, was observed.     

Trapping levels in silicon nitride

The trapping levels in silicon nitride have been investigated using the thermally stimulated current technique. Traps at between 0.50 and 0.90eV below the conduction band of the nitride were found, as well as a distribution of traps at and near the silicon-silicon nitride interface about 0.10eV below the conduction band of the silicon.     

Latest rocket measurements of the solar constant

Three rocket flights which carried a payload of absolute radiometers to measure the solar constant with an accuracy of ±0.5 per cent have been accomplished. Several of the rocket radiometers were duplicates of those aboard the Solar Maximum Mission and Nimbus spacecrafts. The values for the solar constant obtained by the rocket sensors for the three flight dates indicate an increase between the first and latter two flights approximately equivalent to the uncertainty of the measurements. The values for the solar constant for the three flights are 1367, 1372 and 1374 Wm⁻².     

Field-effect-transistor negative-resistance circuit

A negative-resistance circuit that uses two field-effect transistors and two resistors is analysed. This circuit uses one internal power supply and is suitable for realising negative resistances of high values. Some experimental results are also given.     

The Shapes of Peeling Solid Films

A theory is developed to describe the shape of a long thin elastic film peeling from a rigid substrate under a constant load. The theory is verified by static measurements of spring steel strip and by slow peeling experiments using rubber and paint films. Extension of the theory to the case of viscoelastic peeling films demonstrates how the film shape in such a system depends on peeling velocity. Reasonable agreement with experiment is obtained.     

Compensated resistors for high-frequency electrometer applications

The behaviour of electrometer feedback resistors at high frequencies is discussed. It is shown theoretically that the performance of a shielded resistor of this type can be greatly improved by the addition of capacitive coupling between the electrometer output and the centre of the resistor. The improvement has been verified in practice.     

Dislocations at adhesive interfaces in composites

This paper describes interfacial dislocations and suggests that these may contribute to the strength and toughness of adhesive composites. The concept of a dislocation forming at an adhesive interface is outlined and demonstrated experimentally using rubber models. It is shown that such dislocations can stop cracks and strengthen interfaces. Moreover, interfacial dislocations are seen to form spontaneously in an adhesive composite structure. An explanation is therefore provided for the remarkable properties of mother of pearl, an adhesive composite which is predominantly calcium carbonate, but which s much stronger and tougher than limestone because of its peculiar interfaces. In addition, the properties of mother of pearl point towards the practicability of making strong, tough composites from largely inorganic materials like cement.     

The COVA program—Validation of the fast reactor containment code seurbnuk

Extensive studies are underway in the UK and elsewhere to investigate the consequences of a hypothetical core disruptive accident in a fast reactor. Within these studies there is a continuing need to determine the response of the primary containment system to loads generated by such a major release of energy. A number of fast reactor containment codes are currently being developed for this purpose.The COVA (COva VAlidation) program of experiments is being undertaken to provide high quality data against which the codes can be validated. The tests progress from simple bare vessel assemblies to tests incorporating the main axisymmetric features of loop and pool reactor designs.A companion paper in this journal discusses recent developments in the containment code SEURBNUK which is being jointly developed by the UKAEA and JRC Ispra. This paper describes the status of the validation of SEURBNUK against data from the COVA experiments. Considerable progress has been made in the application of the code to the more complex configurations of the later tests which are more representative of reactor geometries and it is concluded that SEURBNUK has reached a stage where it provides a useful calculational capability for containment analysis. Nevertheless, further work is needed to improve the predictions of vessel deformations and roof loadings in some geometries.     

Discovery and development of educational strategies to encourage safe food handling behaviors in cancer patients

Foodborne infections pose a threat to cancer patients who are immunocompromised because of disease or medical therapy. Comprehensive food safety education can raise cancer patients' awareness of risk for foodborne infections and encourage risk-reducing behavior. The objectives of this study were to assess food safety informational needs of cancer patients and to determine factors that may influence prospective educational interventions that foster risk-reducing behaviors. Focus groups with cancer patients were formed, and interviews with health professionals working with cancer patients were conducted. Findings were used to develop three educational resource prototypes for cancer patients. Information from two additional focus groups and interviews with cancer patients was used to evaluate the prototypes before revision and finalization. There was a general awareness among focus group participants that chemotherapy increased their susceptibility to foodborne illness and infections. Participants had a basic knowledge of safe food handling practices but did not necessarily link their awareness of increased susceptibility for infection with their routine food handling practices. When informed of specific high-risk foods, there was skepticism about compliance due to disbelief of the risk, personal preferences for the high-risk food, and lack of information about how to use the recommendation. Most of the health care providers agreed that food safety information should be provided by dietitians, physicians, and nurses, but physicians stated they had little time to do so. Cancer patients expressed positive attitudes toward the educational resource prototypes and willingness to follow the food safety recommendations provided.     

Consumer assessment of safety and date labeling statements on ready-to-eat meat and poultry products designed to minimize risk of listeriosis

Point-of-purchase safety-based labeling guidance on the proper storage and handling of refrigerated ready-to-eat (RTE) meat and poultry products could help reduce the risk of listeriosis. Seniors and pregnant women are two population groups at increased risk of listeriosis due to suppressed or compromised immune systems. We conducted 11 focus groups with senior-aged women and women of childbearing age in Colorado and Ohio to assess consumer awareness of Listeria, storage practices of RTE meat products, perceptions regarding the acceptability and usefulness of common date and potential food safety labeling statements on RTE meat and poultry products, and food safety information needs. Storage times for opened and unopened RTE products varied widely, with opened products often being stored longer than recommended. Women in both age groups paid attention to date labels on packages but varied highly in their interpretation of the statements. "Use by" statements were considered clearer and more helpful than "Sell by" or "Best if used by" labels. Proposed food safety-based labeling statements listing "antilisterial" agents used in RTE products were not well received. However, labels giving consumers instructions on how long they could keep RTE products and when to discard them after opening were considered helpful and well received. Participants indicated the need for further information about Listeria and its control. Educational information at point-of-purchase and where seniors and pregnant women congregate are suggested. Manufacturers are encouraged to provide more complete information on the safe storage and use of ready-to-eat meat and poultry products on package labels.