The orientations of both a nematic liquid crystal fluid and a series of monodisperse glassy−nematic oligofluorenes were investigated on photoalignment films comprising a polymethacrylate backbone with 7-benzoyloxycoumarin pendants. Both classes of liquid crystalline material were found to undergo a transition from a parallel to a perpendicular orientation with reference to the polarization axis of UV-irradiation at a sufficiently high extent of dimerization. The UV−vis and FTIR spectroscopic analyses revealed photostability with irradiation up to a fluence of 10 J/cm2, thereby excluding photodegradation as the basis for the observed crossover. A kinetic model was used to interpret the crossover behavior for irradiation at 25 °C, leading to the conclusion that liquid crystal molecules interact more favorably with coumarin monomers than with dimers. Through thermal annealing above T g followed by cooling to room temperature, a glassy−nematic pentafluorene film was prepared on a photoalignment film, exhibiting an orientational order parameter comparable to that on a rubbed polyimide film. At an increasing oligofluorene chain length, however, a decreasing orientational order parameter emerged, presumably because of the increased annealing temperature that causes an orientational relaxation on the part of the dimerized coumarin moieties.
Polymer cholesteric liquid‐crystal (PCLC) flakes were investigated for their electro‐optical behavior under an applied alternating‐current field. Shaped flakes, fabricated using soft lithography and suspended in dielectric‐fluid‐filled cells, reoriented more uniformly than randomly shaped flakes made by fracturing of PCLC films. Extensive characterization found shaped flakes to be smooth and uniform in size, shape, and thickness. Reorientation in applied fields as low as tens of mVrms μm–1 was fastest for flakes with lateral aspect ratios greater than 1:1, confirming theoretical predictions based on Maxwell–Wagner polarization. Brilliant reflective colors and inherent polarization make shaped PCLC flakes of interest for particle displays.
This paper introduces the assessment procedures which are currently being utilised by the NCVQ. The emphasis on the performance of the Trainee is suggested as a major variable and Trainee competence is shown to revolve around being seen to perform efficiently.Two theoretical positions are shown to underpin the NCVQ version of competence assessment. Functionalism and behaviourism in their more basic forms are very near to the surface of NVQ accreditation. It is demonstrated that both of these theoretical approaches are evident in the developing and emerging NVQ model. Finally, the question of suitability is raised. That is, it is suggested that the model of competence assessment currently being used in Further Education and soon to be introduced into Higher Education, may be unsuitable except perhaps at the more basic level. IntroductionIt is no exaggeration to claim, that the influence of the NCVQ (National Council for Vocational Qualifications) may soon affect all of the post compulsary education sector. From the early 1980s there has been a political move towards change in training and the assessment of skill acquisition. The New Training Initiative (MSC 1981) 1 began the process with suggesting the need to train people for careers in which technology would advance at great speed. This would require a flexible workforce and probable retraining, perhaps on several occasions in one working lifetime. The NTI also began the process of identifying the standards which were required by industry. These were introduced into the Youth Training Scheme as 'Standard Tasks'.From 1984 the standard tasks were grouped into 'Modules of Accreditation'. This was taken further by 'Caterbase' 2 in 1985. This procedure formed the basis for the publication of the first NVQ (National Vocational Qualification) criteria in 1986. NVQ accreditation is available to those forms of training which are written in behavioural terms. That is, they are expressed as outcomes which are observed subsequently in the performance of the Trainee. The NCVQ are very clear that they consider the observable behaviour of the Trainee as the crucial variable.
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