An overview of polymer latex film formation and properties.

The literature on polymer latex film formation has grown enormously in recent times--driven by the need to find alternatives for solvent-based systems with their adverse environmental impacts. Although greater insight has been shown by the use of modern instrumental techniques such as small angle neutron scattering, direct non-radiative energy transfer and atomic force microscopy, the actual mechanisms involved in deforming spherical particles into void-free films are still the subject of controversy and debate. Surfactant-free homopolymer model colloid latices, favoured in academic studies, together with latices containing surfactants whose redistribution can influence film properties, and the more complex copolymer, blended, core-shell and pigmented systems needed to satisfy a full range of film properties are all considered.

The cleaning of polymer colloids.

The current state of knowledge of the cleaning of polymer colloids is reviewed with regard to a wide range of cleaning and characterisation techniques. The type, level and quantity of impurities involved with different polymer latex formulations varies widely. Even for similar formulations, differences in the nature and number of functional groups reported are often a consequence of sometimes subtle differences in the cleaning procedures employed. Not only may surface functionality be affected but also monomer and oligomer extraction procedures may lead to morphological changes in the particles. No single technique alone is likely to be able to remove all impurities. Care is needed to avoid the introduction of new impurities from the equipment, materials and water used as well as possible contamination from atmospheric carbon dioxide, bacteria and fungi. These factors also need to be considered in the storage of latex particle standards.

Providing continuity in a "firm" case management system.

Four general medicine units were divided into two "firms" to improve patient outcomes and ensure continuity of care. All members remain part of their firm for as long as they are employed. The nurse case managers remain constant in both inpatient and outpatient settings and coordinate discharge planning.

Developing core competencies for medical/surgical nursing.

The development of competency-based education is a task requiring the skills of educators and expert clinicians. This article provides information on a competency-based core orientation for medical/surgical nursing.

Specificity of the mineralocorticoid receptor: crucial role of 11beta-hydroxysteroid dehydrogenase.

Research on the enzyme 11beta-hydroxysteroid dehydrogenase, initially performed on congenital deficiency of the enzyme, and later work on deficiency of the enzyme after licorice and carbenoxolone administration, led to the hypothesis that 11beta-hydroxysteroid dehydrogenase conferred specificity on the mineralocorticoid receptor.

Estimated spectrum of a 4-MV therapeutic beam.

We have made a comparative investigation of the estimated spectra obtained by the Laplace transform analysis of the transmitted exposure data measured in an absorption study of a 4-MV x-ray beam. Four transform pair models currently used with this method have been evaluated. It has been determined that the Archer-Wagner model provides a valid representation of the measured transmission data and yields an estimated spectrum which most closely resembles a Monte Carlo spectrum calculated for a 4-MV therapeutic x-ray beam available from a typical medical accelerator.

Cell cycle and the concept of physiological age with special reference to pyruvate kinase activity in WI-38 cells.

WI-38 cells were synchronized by mitotic collection and periodically assayed for pyruvate kinase activity. The kinetics of the synchronous cohort were determined by continuous labelling index and by mitotic index. The experimental data were analysed by computer using a state vector model to yield the probability density functions for phase transit times and for cell physiological ages. Pyruvate kinase activity for these cells as a function of physiological age was then examined using the computer model. Considering DNA synthesis, pyruvate kinase activity and mitosis to be markers of physiological age, it was found that a model which assumes that a cohort of synchronized cells desynchronizes irreversibly and uniformly from one age marker to the next is incompatible with the experimental data. For example, the times over which cells entered the S phase were too widely distributed to be consistent with the mitotic index data. Also, for pyruvate kinase activity to be a function of physiological age alone, the cell ages were probably too dispersed to be compatible with the experimental enzyme data. Alternative models for cell physiological ageing are presented, which are compatible with the experimental data.

Introduction of partographic records in a District Hospital in Zambia and development of nomograms of cervical dilatation.

Partographic records of labour have been successfully introduced in a district hospital in Zambia. Nomograms of cervical dilatation show no significant difference compared to those obtained by other workers in other parts of the world. There was no difference in the duration of the active phase of the 1st stage of labour between multiparous patients (para 1--4) and grand multiparous patients (para greater than 4).