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Articles 1 - 9 of 9
Full-Text Articles in Physics
Interaction Of Carbon Nanotubes With Sugar Complexes, Alan Casey, Gordon Farrell, Mary Mcnamara, Hugh Byrne, Gordon Chambers
Interaction Of Carbon Nanotubes With Sugar Complexes, Alan Casey, Gordon Farrell, Mary Mcnamara, Hugh Byrne, Gordon Chambers
Articles
The interaction of carbon nanotubes with soft organic molecules such as cyclodextrins and other saccarides has recently been shown to produce water soluble composites. Such systems offer considerable advantages over polymer based composites due to their biocompatibility and noncovalent coupling which can potentially preserve the unique properties of the tubes. The mechanism of interaction for such systems has been proposed to be dominated by hydrophobic and hydrophilic interactions along the surface of the tube. However efforts to characterise and rationalise such noncovalent interactions between the sugar-based materials and the carbon nanotubes have been slow to emerge. In this study a …
Polarized He-3 Gas Compression System Using Metastability-Exchange Optical Pumping, D. S. Hussey, D. R. Rich, A. S. Belov, X. Tong, H. Yang, C. Bailey, C. D. Keith, J. Hartfield, G. D. R. Hall, T. C. Black, W. M. Snow, T. R. Gentile, W. C. Chen, Gordon L. Jones, Eileen Wildman '01
Polarized He-3 Gas Compression System Using Metastability-Exchange Optical Pumping, D. S. Hussey, D. R. Rich, A. S. Belov, X. Tong, H. Yang, C. Bailey, C. D. Keith, J. Hartfield, G. D. R. Hall, T. C. Black, W. M. Snow, T. R. Gentile, W. C. Chen, Gordon L. Jones, Eileen Wildman '01
Articles
Dense samples (10-100 bar cm) of nuclear spin polarized He-3 are utilized in high energy physics, neutron scattering, atomic physics, and magnetic resonance imaging. Metastability exchange optical pumping can rapidly produce high He-3 polarizations (≈ 80%) at low pressures (few mbar). We describe a polarized He-3 gas compressor system which accepts 0.26 bar l h(-1) of He-3 gas polarized to 70% by a 4 W neodymium doped lanthanum magnesium hexaluminate (Nd:LMA) laser and compresses it into a 5 bar cm target with final polarization of 55%. The spin relaxation rates of the system's components have been measured using nuclear magnetic …
Characterisation Of An Acrylamide-Based Photopolymer For Data Storage Utilizing Holographic Angular Multiplexing, Hosam Sherif, Izabela Naydenova, Suzanne Martin, Colm Mcginn, Vincent Toal
Characterisation Of An Acrylamide-Based Photopolymer For Data Storage Utilizing Holographic Angular Multiplexing, Hosam Sherif, Izabela Naydenova, Suzanne Martin, Colm Mcginn, Vincent Toal
Articles
An acrylamide-based photopolymer formulated in the Centre for Industrial and Engineering Optics has been investigated with a view to further optimisation for holographic optical storage. Series of 18 to 30 gratings were angularly multiplexed in a volume of photopolymer layer at a spatial frequency of 1500 lines/mm. Since the photopolymer is a saturable material, an exposure scheduling method was used to exploit the entire dynamic range of the material and allow equal strength holographic gratings to be recorded. This investigation yielded the photopolymer M/# for moderately thin layers. Photopolymer temporal stability was also studied by measuring variations of material shrinkage, …
Structural Property Relationships In Conjugated Polymers, Patrick Lynch, Luke O'Neill, J. Whelan, Mary Mcnamara, Hugh Byrne
Structural Property Relationships In Conjugated Polymers, Patrick Lynch, Luke O'Neill, J. Whelan, Mary Mcnamara, Hugh Byrne
Articles
The synthesis of a series of PPV derivative polymers by the Wittig-Horner reaction is described. The structure of each polymer is varied and the effects of these variations on the optical properties is explored. The effects of alkyloxy side chains is observed between the PPV derivatives Poly(-p-phenylvinylene-co-2,5-bis-octyloxy phenylvinylene.) PPV-OPV and Poly (para-2,5-bis-(n-octyloxy)-phenylvinylene) POPV. The phenyl units of the soluble PPV derivative POPV are replaced by alternate naphthyl units in the polymer Poly(2,5-bis(n-octyloxy)-1,4-phenylene vinylene-1,5-bis(n-octyloxy)-2,6-naphthylene vinylene) POPN-ONV and then fully by naphthyl units in Poly(2,6-bis-(n-octyloxy)-1,5-NaphthyleneVinylene) PONV. The addition of alkyloxy sidechains served to red shift the fluorescence emission as expected. The systematic …
Investigation Of The Effect Of Subcutaneous Fat On Image Quality Performance Of 2d Conventional Imaging And Tissue Harmonic Imaging, Jacinta Browne, Amanda Watson, Peter Hoskins, Alex Elliott
Investigation Of The Effect Of Subcutaneous Fat On Image Quality Performance Of 2d Conventional Imaging And Tissue Harmonic Imaging, Jacinta Browne, Amanda Watson, Peter Hoskins, Alex Elliott
Articles
Tissue harmonic imaging (THI) has been reported to improve contrast resolution, tissue differentiation and overall image quality in clinical examinations. However, a study carried out previously by the authors (Browne et al. 2004) found improvements only in spatial resolution and not in contrast resolution or anechoic target detection. This result may have been due to the homogeneity of the phantom. Biologic tissues are generally inhomogeneous and THI has been reported to improve image quality in the presence of large amounts of subcutaneous fat. The aims of the study were to simulate the distortion caused by subcutaneous fat to image quality …
Modernization Of The Hilger And Watts Guage-Block Interferometer, Michael O'Hora, Brian Bowe, Vincent Toal, Sean Peyton
Modernization Of The Hilger And Watts Guage-Block Interferometer, Michael O'Hora, Brian Bowe, Vincent Toal, Sean Peyton
Articles
The Hilger & Watts gauge-block interferometer was designed and manufactured commercially in the 1950s. The instrument uses isotope lamps as wavelength standards to perform absolute length calibration of gauge blocks (slip gauges) up to 100 mm in length, to an accuracy of approximately 1 ppm. It is entirely manually operated. In order to make the instrument more suitable for the modern laboratory, new hardware has been added, and a customized software package developed to automate the measurement process. This paper shows how interferograms may be imaged successfully at each of the eight available wavelengths, and the critical fringe fraction measurement …
The Simultaneous Onset And Interaction Of Taylor And Dean Instabilities In A Couette Geometry, C. P. Hills, A. P. Bassom
The Simultaneous Onset And Interaction Of Taylor And Dean Instabilities In A Couette Geometry, C. P. Hills, A. P. Bassom
Articles
The fluid flow between a pair of coaxial circular cylinders generated by the uniform rotation of the inner cylinder and an azimuthal pressure gradient is susceptible to both Taylor and Dean type instabilities. The flow can be characterised by two parameters: a measure of the relative magnitude of the rotation and pressure effects and a non-dimensional Taylor number. Neutral curves associated with each instability can be constructed but it has been suggested that these curves do not cross but rather posses `kinks'. Our work is based in the small gap, large wavenumber limit and considers the simultaneous onset of Taylor …
Structure-Property Relationships For Electron-Vibrational Coupling In Conjugated Organic Oligomeric Systems, Luke O'Neill, Hugh Byrne
Structure-Property Relationships For Electron-Vibrational Coupling In Conjugated Organic Oligomeric Systems, Luke O'Neill, Hugh Byrne
Articles
A series of ð-conjugated oligomers containing one to six monomer units were studied by absorption and photoluminescence spectroscopy. As is common for these systems, a linear relationship between the positioning of the lowest-energy absorption and the highest-energy photoluminescence maxima plotted versus inverse conjugation length is observed, in good agreement with a simple nearly free electron model, one of the earliest descriptions of the properties of one-dimensional organic molecules. It was observed that the Stokes shift and therefore Huang-Rhys factor also exhibit a well-defined relationship with increasing conjugation length, implying a correlation between the electron-vibrational coupling and chain length. This correlation …
Structure Property Relationships In Organic Conjugated Systems, Luke O'Neill, Patrick Lynch, Mary Mcnamara
Structure Property Relationships In Organic Conjugated Systems, Luke O'Neill, Patrick Lynch, Mary Mcnamara
Articles
A series of π conjugated oligomers were studied by absorption and photoluminescence spectroscopy. A linear relationship between the positioning of the absorption and photoluminescence maxima plotted against inverse conjugation length is observed. The relationships are in good agreement with the simple particle in a box method, one of the earliest descriptions of the properties of one-dimensional organic molecules. In addition to the electronic transition energies, it was observed that the Stokes shift also exhibited a well-defined relationship with increasing conjugation length, implying a correlation between the electron-vibrational coupling and chain length. This correlation is further examined using Raman spectroscopy, whereby …