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Full-Text Articles in Physics

Controlling The Optical Properties Of A Conjugated Co-Polymer Through Variation Of Backbone Isomerism And The Introduction Of Carbon Nanotubes, A. Dalton, J. Coleman, M. In Het Panhuis, B. Mccarthy, A. Drury, W. Blau, J. Nunzi, Hugh Byrne Jan 2001

Controlling The Optical Properties Of A Conjugated Co-Polymer Through Variation Of Backbone Isomerism And The Introduction Of Carbon Nanotubes, A. Dalton, J. Coleman, M. In Het Panhuis, B. Mccarthy, A. Drury, W. Blau, J. Nunzi, Hugh Byrne

Articles

The need to control the formation of weakly emitting species in polymers such as aggregates and excimers, which are normally detrimental to device performance, is illustrated for the example of the polymer poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene), using the model compound, 2,5-dioctyloxy-p-distyrylbenzene as a comparison. Two different methods, namely a Homer-Emmons polycondensation in dimethylformamide (DMF) and a Wittig polycondensation in dry toluene, have been used during synthesis resulting in a polymer with a predominantly trans-vinylene backbone and a polymer with a predominantly cis-vinylene backbone, respectively. Photoluminescence and absorption spectroscopy indicate that the polymer forms aggregate species in solution with spectra that are distinctly red-shifted …


Eddy Structures Induced Within A Wedge By A Honing Circular Arc, C. P. Hills Jan 2001

Eddy Structures Induced Within A Wedge By A Honing Circular Arc, C. P. Hills

Articles

In this paper we outline an expeditious numerical procedure to calculate the Stokes flow in a corner due to the rotation of a scraping circular boundary. The method is also applicable to other wedge geometries. We employ a collocation technique utilising a basis of eddy (similarity) functions introduced by Moffatt (1964) that allows us to satisfy automatically the governing equations for the streamfunction and all the boundary conditions on the surface of the wedge. The circular honing problem thereby becomes one-dimensional requiring only the satisfaction of conditions on the circular boundary. The advantage of using the Moffatt eddy functions as …


Eddies Induced In Cylindrical Containers By A Rotating End Wall, Christopher Hills Jan 2001

Eddies Induced In Cylindrical Containers By A Rotating End Wall, Christopher Hills

Articles

The flow generated in a viscous liquid contained in a cylindrical geometry by a rotating end wall is considered. Recent numerical and experimental work has established several distinct phases of the motion when fluid inertia plays a significant role. The current paper, however, establishes the nature of the flow in the thus far neglected low Reynolds number regime. Explicitly, by employing biorthogonality relations appropriate to the current geometry, it is shown that a sequence of exponentially decaying eddies extends outward from the rotating end wall. The cellular structure is a manifestation of the dominance of complex eigensolutions to the homogeneous …


A Review Of The Different Methods For Assessing Standing Balance, Jacinta Browne, N. J. O'Hare Jan 2001

A Review Of The Different Methods For Assessing Standing Balance, Jacinta Browne, N. J. O'Hare

Articles

This paper is a review of the balance assessment methods currently used to evaluate standing balance. Most of the presently available instrumentation appears to be more suited to research laboratories than to routine clinical situations. Functional assessments of balance appear to be the quickest test to administer and do not require expensive equipment however only gross changes in balance can be detected making them suitable as a screening tool for identifying subject’s needing more thorough evaluation. Force platforms appear to be most suited balance assessment instrumentation to the clinical situation since it produces a real time display and can detect …