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Articles 1 - 11 of 11
Full-Text Articles in Physics
Photopolymers: Beyond The Standard Approach To Photosensitisation, Izabela Naydenova, Suzanne Martin, Vincent Toal
Photopolymers: Beyond The Standard Approach To Photosensitisation, Izabela Naydenova, Suzanne Martin, Vincent Toal
Articles
A photopolymerizable material for use in the visible normally consists of a dye sensitizer, a free radical generator, monomer/monomers and, optionally, a binder, and is prepared usually as a dry or liquid film. Upon illumination with light of appropriate wavelength, a photopolymerisation reaction is triggered, leading to a change in the film’s refractive index. Because the presence of the dye is essential, the film is usually made sensitive to light during its preparation. Here we separate the film preparation and the sensitisation processes. In this way the photopolymerisation process can be used to detect dye labelled analytes, providing an alternative …
Characterisation Of The Humidity And Temperature Responses Of A Reflection Hologram Recorded In Acrylamide-Based Photopolymer, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Characterisation Of The Humidity And Temperature Responses Of A Reflection Hologram Recorded In Acrylamide-Based Photopolymer, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin
Articles
The humidity and temperature responses of a reflection hologram recorded in a self-processing photopolymer layer have been characterised by measurement of the position of the maximum intensity in the spectral response of the hologram. It has been demonstrated that such a hologram can be used for indication of the relative humidity (RH) in a specific temperature range. The operational range and reversibility of the holograms have been characterised in a controlled humidity and temperature environment. The humidity studies were carried out in the range from 10 to 80% RH and the temperature range under study was 15 – 50 ºC.
Swcnt Suppress Inflammatory Mediator Responses In Human Lung Epithelium In Vitro, Eva Herzog, Hugh Byrne, Maria Davoren, Anke-Gabriele Lenz, Albert Duschl, Gertie Janneke Oostingh
Swcnt Suppress Inflammatory Mediator Responses In Human Lung Epithelium In Vitro, Eva Herzog, Hugh Byrne, Maria Davoren, Anke-Gabriele Lenz, Albert Duschl, Gertie Janneke Oostingh
Articles
Single walled carbon nanotubes have gained enormous popularity due to a variety of potential applications which will ultimately lead to increased human and environmental exposure to these nanoparticles. This study was carried out in order to evaluate the inflammatory response of immortalised and primary human lung epithelial cells (A549 and NHBE) to single walled carbon nanotube samples (SWCNT). Special focus was placed on the mediating role of lung surfactant on particle toxicity. The toxicity of SWCNT dispersed in cell culture medium was compared to that of nanotubes dispersed in dipalmitoylphosphatidylcholine (DPPC, the main component of lung lining fluid). Exposure was …
Double-Glazing Interferometry, Vincent Toal, Emilia Mihaylova
Double-Glazing Interferometry, Vincent Toal, Emilia Mihaylova
Articles
This note describes how white light interference fringes can be seen by observing the Moon through a double-glazed window. White light interferometric fringes are normally observed only in a well-aligned interferometer whose optical path difference is less than the coherence length of the light source, which is approximately one micrometer for white light. Obtaining such fringes in a Michelson interferometer is not a trivial task.1 The interferometer is typically illuminated with a monochromatic source and the path length difference adjusted with a wedge angle between the interferometer mirrors so that five or six vertical fringes are visible, indicating nearly equal …
Simple Versatile Shearing Interferometer Suitable For Measurements On A Microscopic Scale, Emilia Mihaylova, Vincent Toal
Simple Versatile Shearing Interferometer Suitable For Measurements On A Microscopic Scale, Emilia Mihaylova, Vincent Toal
Articles
Microelectromechanical systems (MEMS) behave differently from massive samples. Conventional testing and inspection techniques usually fail at the microscale. Recently there has been an increasing interest in the application of optical techniques for microstructure testing, because they are high-resolution, non-contact, full-field, fast and relatively inexpensive. New interferometric systems, which are suitable for microscopic optical metrology, are of interest for engineering and industrial applications. A modified electronic speckle pattern shearing interferometer (ESPSI) with a very simple shearing device has been designed for metrology applications on the microscale. The shearing device consists of two partially reflective glass plates. The reflection coefficients of the …
Optical And Holographic Characteristics Of Photopolymer Layers, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Suzanne Martin, Vincent Toal, Simeon Sainov
Optical And Holographic Characteristics Of Photopolymer Layers, Temenujka Yovcheva, Izabela Naydenova, Ivanka Vlaeva, Suzanne Martin, Vincent Toal, Simeon Sainov
Articles
In the present work the optical and holographic characteristics of acrylamide-based photopolymer layers are studied. For the first time the refractive index change of a liquid acrylamide photopolymer due to exposure at 532 nm is obtained using a critical angle laser micro-refractometer. The 30 mm thick solid photopolymer films are prepared by casting on glass substrates. Bragg holographic gratings with spatial frequencies of 710 mm-1, 1050 mm-1 and 1600 mm-1 are recorded using a diode laser operating at 532 nm wavelength. The diffraction efficiency dependence on the exposure energy is investigated. The obtained results are compared with the Stetson holographic …
Spectroscopic Study Of The Dimerisation Process Of Iron Protoporphyrin Ix, K. Dziedzic-Kocurek, Hugh Byrne, A. Swiderski, J. Stanek
Spectroscopic Study Of The Dimerisation Process Of Iron Protoporphyrin Ix, K. Dziedzic-Kocurek, Hugh Byrne, A. Swiderski, J. Stanek
Articles
The commercial protoporphyrin IX, iron-ferriprotoporphyrin IX-chloride and synthesized iron porphyrin μ-oxo-dimers were examined by UV/vis absorption and fluorescence, Fourier transformed infrared spectroscopy, resonance Raman, X-ray absorption, Mössbauer spectroscopy and SQUID. The evidence of Fe-O-Fe antiferromagnetic coupling concluded from SQUID and Mössbauer in the case of samples containing dimerized forms confirmed the presence of the oxo-bridges. In this paper the results of UV/vis, fluorescence, Fourier transform infrared FTIR and Raman spectroscopies are reported and discussed. The study is based on the comparison of the free-base protoporphyrin IX, Fe-PPIX-Cl and the synthesized dimerized specimen. The vibrational modes in two energy regions i.e. …
Optical Properties Of Silica-Mfi Doped Acrylamide-Based Photopolymer, Tzvetanka Babeva, Rosen Todorov, Svetlana Mintova, Temenujka Yovcheva, Izabela Naydenova, Vincent Toal
Optical Properties Of Silica-Mfi Doped Acrylamide-Based Photopolymer, Tzvetanka Babeva, Rosen Todorov, Svetlana Mintova, Temenujka Yovcheva, Izabela Naydenova, Vincent Toal
Articles
The optical properties of acrylamide-based photopolymer doped with pure silica MFI-type zeolites are studied by refractometric and spectrophotometric means. Dynamic Light Scattering and Transmission Electron Microscopy are used for zeolite characterization and laser refractometry and White Light Interferometric profilometry are used for surface characterization of the composites. Refractive indices and absorption coefficients of composites are determined from their transmittance and reflectance spectra. The calculated dispersion curves are further used for deriving the zeolites refractive index and porosity and the latter compared to the values of total pore volume obtained from N2-sorption measurements. The impact of the doping level on the …
Converging Flow Between Coaxial Cones, O. Hall, A. D. Gilbert, C. P. Hills
Converging Flow Between Coaxial Cones, O. Hall, A. D. Gilbert, C. P. Hills
Articles
Fluid flow governed by the Navier-Stokes equation is considered in a domain bounded by two cones with the same axis. In the first, 'non-parallel' case, the two cones have the same apex and different angles θ = α and β in spherical polar coordinates (r, θ, φ). In the second, 'parallel' case, the two cones have the same opening angle α, parallel walls separated by a gap h and apices separated by a distance h/sinα. Flows are driven by a source Q at the origin, the apex of the lower cone in the parallel case. The Stokes solution for the …
Nonaxisymmetric Stokes Flow Between Concentric Cones, O. Hall, C. P. Hills, A. D. Gilbert
Nonaxisymmetric Stokes Flow Between Concentric Cones, O. Hall, C. P. Hills, A. D. Gilbert
Articles
We study the fully three-dimensional Stokes flow within a geometry consisting of two infinite cones with coincident apices. The Stokes approximation is valid near the apex and we consider the dominant flow features as it is approached. The cones are assumed to be stationary and the flow to be driven by an arbitrary far-field disturbance. We express the flow quantities in terms of eigenfunction expansions and allow for the first time for nonaxisymmetric flow regimes through an azimuthal wave number. The eigenvalue problem is solved numerically for successive wave numbers. Both real and complex sequences of eigenvalues are found, their …
Holographic Recording In Acrylamide Photopolymers: Thickness Limitations, Mohammad Mahmud, Izabela Naydenova, Nitesh Pandey, Tzvetanka Babeva, Raghavendra Jallapuram, Suzanne Martin, Vincent Toal
Holographic Recording In Acrylamide Photopolymers: Thickness Limitations, Mohammad Mahmud, Izabela Naydenova, Nitesh Pandey, Tzvetanka Babeva, Raghavendra Jallapuram, Suzanne Martin, Vincent Toal
Articles
Holographic recording in thick photopolymer layers is important for application in holographic data storage, volume holographic filters and correlators. Here, the characteristics of acrylamidebased photopolymer layers having thickness from 250 μm to 1-mm were studied. For each layer thickness samples with three different values of absorbance were studied. By measuring both the first order diffraction efficiency growth of holographically recorded gratings and studying the diffraction patterns obtained, the influence of scattering on the diffraction efficiency of thick volume holographic gratings was analyzed. It was observed that above a particular thickness and absorbance, the first order diffraction efficiency significantly decreased because …