Chain Deformation for a Polymer Melt under Shear

We used a Couette cell placed within an NMR microscopy apparatus to examine molecular alignment in polydimethylsiloxane melts under shear. 1H dipolar interactions are used to examine main chain ordering while 2H NMR quadrupole splittings are measured in a deuterated oligomer probe, in each case selectively observing different alignment orientations with respect to the flow field. While the main chain results are consistent with the alignment tensor as measured by birefringence, the oligomer senses a uniaxial environment whose director is normal to the velocity-vorticity plane. In the light of these results we propose supramolecular ordering involving polymer stratification

Atlas of radiographic features of osteoarthritis of the ankle and hindfoot

To develop a radiographic atlas of osteoarthritis (OA) for use as a template and guide for standardized scoring of radiographic features of OA of the ankle and hindfoot joints

Mergers and change management at a micro level: a case study.

The transformation of the South African higher education landscape resulted in, among other things, the merger of three distance education institutions: Unisa, VUDEC and TSA. The macro level of the merger will no doubt be studied in detail. This article explores a micro level process for two departments merged by a top-down decision that did not take cognisance of their dissimilar functions and structures. The result was both a merger and a demerging process. The two departments first had to confront the realities of their different functions and structures before a reconfiguration could occur, including the emergence of a strategic plan focusing on aspects such as specific contribution, drivers, objectives and structure. The change management principles adopted to ensure the success of the process are outlined, analysed and reflected upon

Dynamics of weakly aggregated colloidal particles - discussion

We discuss the behaviour of the dynamics of colloidal particles with a weak attractive interparticle interaction that is induced through the addition of polymer to the solvent. We briefly review the description of their behaviour in terms of the jamming phase diagram, which parametrized the fluid–to–solid transition due to changes in volume fraction, attractive energy or applied stress. We focus on a discussion of ageing of the solid gels formed by these colloid–polymer mixtures. They exhibit a delayed collapse induced by gravity. The time evolution of the height of the sediment exhibits an unexpected scaling behaviour, suggesting a universal nature to this delayed collapse. We complement these measurements of the scaling of the collapse with microscopic investigations of the evolution of the structure of the network using confocal microscopy. These results provide new insight into the origin of this ageing behaviour