Physical Sciences and Mathematics Commons^™

Diffractive Optical Elements With A Large Angle Of Operation Recorded In Acrylamide Based Photopolymer On Flexible Substrates, Hoda Akbari, Izabela Naydenova, Lina Persechini, Sean Garner, Pat Cimo, Suzanne Martin

Articles

A holographic device characterised by a large angular range of operation is under development. The aim of this study is to increase the angular working range of the diffractive lens by stacking three layers of high efficiency optical elements on top of each other so that light is collected (and focussed) from a broader range of angles. The angular range of each individual lens element is important, and work has already been done in an acrylamide-based photosensitive polymer to broaden the angular range of individual elements using holographic recording at a low spatial frequency.This paper reports new results on the …

Antimicrobial Properties Of Nano-Silver: A Cautionary Approach To Ionic Interference, Kate Sheehy, Alan Casey, Anna Murphy, Gordon Chambers

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Hypothesis: Metallic nanoparticles such as nano-silver have found many applications as alternative antimicrobials in recent years. However methods for determining their proposed antimicrobial activity have received little attention to date. The disk diffusion assay is commonly used as a demonstration of antimicrobial properties and is a regular feature in synthetic nanoparticle papers. The aim of this study was to assess its effectiveness in demonstrating the ‘‘nanoparticle specific’’ antimicrobial properties in the absence of ionic contributions from unreacted reducing agents and or impurities. Experiments: The disk diffusion assay was carried out on a range of silver nanoparticles, both in-house synthesised and …

Competitive Evaluation Of Data Mining Algorithms For Use In Cassification Of Leukocyte Subtypes With Raman Microspectroscopy, Adrian Maguire, I. Vega-Carrascal, Jane Bryant, Lisa White, Orla Howe, Fiona Lyng, Aidan Meade

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Raman microspectroscopy has been investigated for some time for use in label-free cell sorting devices. These approaches require coupling of the Raman spectrometer to complex data mining algorithms for identification of cellular subtypes such as the leukocyte subpopulations of lymphocytes and monocytes. In this study, three distinct multivariate classification approaches, (PCA-LDA, SVMs and Random Forests) are developed and tested on their ability to classify the cellular subtype in extracted peripheral blood mononuclear cells (T-cell lymphocytes from myeloid cells), and are evaluated in terms of their respective classification performance. A strategy for optimisation of each of the classification algorithm is presented …

Raman Microspectroscopy For The Early Detection Of Pre-Malignant Changes In Cervical Tissue, Nosheen Rashid, Haq Nawaz, Kelvin W. Poon, Franck Bonnier, Salih Bakhiet, Cara Martin, John O'Leary, Hugh Byrne, Fiona Lyng

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Cervical cancer is the third most common cancer affecting women worldwide. The mortality associated with cervical cancer can, however, be significantly reduced if the disease is detected at the pre-malignant stage. The aim of this study was to evaluate the potential of Raman microspectroscopy for elucidation of the biochemical changes associated with the pre-malignant stages of cervical cancer. Formalin fixed paraffin preserved tissue sections from cervical biopsies classified as negative for intraepithelial lesion and malignancy (NILM), low grade squamous intraepithelial lesion (LSIL) or high grade squamous intraepithelial lesion (HSIL) were analysed by Raman spectral mapping. Raman mapping, with K-Means Cluster …

Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick Cullen, Paula Bourke

Articles

Cold atmospheric plasma (CAP) is produced by ionizing a chosen gas, thereby creating charged and reactive species. The reactive species generated are capable of inducing a range of biomedically relevant interactions including blood coagulation. However, the underlying biochemical processes of plasma-assisted blood coagulation are largely unknown, and data quantifying blood clot formation or the impact of system parameters on the intensity of the blood clot are scarce. In this study, blood coagulation was quantified by measuring hemoglobin absorbance. System parameters of the kINPen plasma jet were investigated and compared, including treatment time, distance from the plasma source and gas flow …

An Assessment Of The Energy Generation Potential Of Photovoltaic Systems In Cameroon Using Satellite-Derived Solar Radiation Datasets, Lacour Ayompe, Aidan Duffy

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Cameroon like most developing countries does not have a reliable network of surface observation stations for collecting weather data. This has been a major drawback for accurate assessment of the energy generation potential of photovoltaic systems in Cameroon. A viable alternative is to obtain site-specific solar irradiation from satellite-derived datasets. In this paper, the energy output, capacity factor and performance ratio of photovoltaic systems in 33 locations spread around ten regions in Cameroon have been evaluated using monthly average daily global horizontal solar irradiation from long-term satellitederived data available in Solar GIS software. An economic assessment revealed that a simple …

Dressing Method And Quadratic Bundles Related To Symmetric Spaces: Vanishing Boundary Conditions, Tihomir Valchev

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We consider quadratic bundles related to Hermitian symmetric spaces of the type SU(m+n)/S(U(m) x U(n)). The simplest representative of the corresponding integrable hierarchy is given by a multi-component Kaup-Newell derivative nonlinear Schroedinger equation which serves as a motivational example for our general considerations. We extensively discuss how one can apply Zakharov-Shabat's dressing procedure to derive reflectionless potentials obeying zero boundary conditions. Those could be used for one to construct fast decaying solutions to any nonlinear equation belonging to the same hierarchy. One can distinguish between generic soliton type solutions and rational solutions.

A Soft Condensed Matter Approach Towards Mathematical Modelling Of Mass Transport And Swelling In Food Grains, Michael Chapwanya, N. Misra

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Soft condensed matter (SCM) physics has recently gained importance for a large class of engineering materials. The treatment of food materials from a soft matter perspective, however, is only at the surface and is gaining importance for understanding the complex phenomena and structure of foods. In this work, we present a theoretical treatment of navy beans from a SCM perspective to describe the hydration kinetics. We solve the transport equations within a porous matrix and employ the Flory–Huggin’s equation for polymer–solvent mixture to balance the osmotic pressure. The swelling of the legume seed is modelled as a moving boundary with …

One-Dimensional Weakly Nonlinear Model Equations For Rossby Waves, David Henry, Rossen Ivanov

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In this study we explore several possibilities for modelling weakly nonlinear Rossby waves in fluid of constant depth, which propagate predominantly in one direction. The model equations obtained include the BBM equation, as well as the integrable KdV and Degasperis-Procesi equations.

Slow Plastic Creep Of 2d Dusty Plasma Solids, Angela Douglass, Peter Hartmann, Aniko Zs. Kovacs, Jorge C. Reyes, Lorin S. Matthews, Truell W. Hyde

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We report complex plasma experiments, assisted by numerical simulations, providing an alternative qualitative link between the macroscopic response of polycrystalline solid matter to small shearing forces and the possible underlying microscopic processes. In the stationary creep regime we have determined the exponents of the shear rate dependence of the shear stress and defect density. We show that the formation and rapid glide motion of dislocation pairs in the lattice are dominant processes.

Developments Of Cobalt Ferrite Nanoparticles Prepared By The Sol–Gel Process, M. Sajjiaa, Mohamed Oubaha, M. Hasanuzzaman, A.G. Olabi

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In the phase of the study reported, the sol–gel technique was followed in the preparation of cobalt ferrite amorphous powder following the same procedure which was selected as the best approach as described in a previous study. It was assumed that there must be a correlation between the heat treatment operational parameters and the structural properties of the material being synthesized. Similarly, it was understood that some heat treatment is necessary to completely decompose the organic and nitrate contents present in the amorphous powder. Having ensured that the heat treatment parameters could be changed without producing a material with poorer …

Studies On The Synthesis Of Orthogonally Protected Azalanthionines, And Of Routes Towards B-Methyl Azalanthionines, By Ring-Opening Of N-Activated Aziridine-2-Crboxylates, Keith O'Brien, Keith Ó Proinsias, Fintan Kelleher

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Orthogonally protected azalanthionines were successfully synthesised by the ring-opening of N-activated aziridine-2-carboxylates with protected diaminopropanoic acids (DAPs). The required DAPs were also prepared by ring-opening of N-activated aziridine-2-carboxylates with para-methoxybenzylamine, but it was found that the choice of aziridine protecting groups dictated both the success of the reaction as well as the regioselectivity of the isolated products. Attempts to extend the methodology to the preparation of the more sterically demanding b-methyl azalanthionines have, so far, been unsuccessful.

Free Energies In A General Non-Local Theory Of A Material With Memory, Giovambattista Amendola, Mauro Fabrizio, John Murrough Golden

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A general theory of non-local materials, with linear constitutive equations and memory effects, is developed within a thermodynamic framework. Several free energy and dissipation functionals are constructed and explored. These include an expression for the minimum free energy and a functional that is a free energy for important categories of memory kernels and is explicitly a functional of the minimal state. The functionals discussed have a similar general form to the corresponding expressions for simple materials. A number of new results are derived for them, most of which apply equally to both types of material. In particular, detailed formulae are …

Metal-Organic Frameworks Based On Pyridyl-Tetrazole Ligands Containing Ester Or Carboxylate Pendant Arms, Ursula Sheridan, John Gallagher, Morten Bjerrum, Adrienne Fleming, Fintan Kelleher, John Mcginley

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The coordination of pyridyl-tetrazole derivatives containing ester substituents, at either the N-1 or N-2 position of the tetrazole ring, with copper(II) chloride results in the formation of either 1:1 or 1:2 copper to ligand complexes, depending on the ligand. However, when the ester functionality is changed to a carboxylate group, the resulting complexation reactions yield metal-organic frameworks. The resulting structures vary dramatically in pore size, depending on both reaction solvents and position of carboxylate group on the tetrazole ring. Despite the presence of sodium cations in the reaction mixtures, no sodium incorporation was ever observed in any of the complexes. …

Free Energies For Materials With Memory In Terms Of State Functionals, John Murrough Golden

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Abstract The aim of thiswork is to determinewhat free energy functionals are expressible as quadratic forms of the state functional It which is discussed in earlier papers. The single integral form is shown to include the functional wF proposed a few years ago, and also a further category of functionals which are easily described but more complicated to construct. These latter examples exist only for certain types of materials. The double integral case is examined in detail, against the background of a newsystematic approach developed recently for double integral quadratic forms in terms of strain history, which was used to …

Development Of A Novel Hybrid Aluminum-Based Sol-Gel Materials: Application To The Protection Of Aa2024-T3 Alloys In Alkaline Environment, Mohamed Oubaha, Padinchare Covilakath Rajath Varma, Brendan Duffy, Zuhair Mattoug Gasem, Steven J. Hinder

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Extensive research on environmentally complaint sol-gel coatings is currently underway for a wide range of applications. Sol-gel technology combines the synergistic properties of inorganic and organic components to design nanostructured coating materials with advanced physical properties. Through a judicious choice of precursors and additives improved performances, such as chemical resistance or pH stability, it can be achieved. This is of particular interest for copper rich AA 2024-T3 aluminium alloys used on aircraft, where increase in local pH occurs at corrosion sites. This work focuses on improving the alkaline stability and anticorrosion properties of such a sol-gel coatings on AA2024-T3 by …

The Behavior Of Midsets When Repeatedly Taking The Midset Of Two Lines In L1 Geometry, Joshua M. Fitzhugh, David L. Farnsworth

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We study the outcome of taking midsets of two lines in ℓ1 geometry.We establish the algorithm for repeatedly finding these midsets and characterize the limiting midsets.We discuss the issue of angle measurement in Minkowski geometries, especially with respect to the limiting midsets.

Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper

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The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with

Adopting Agile Practices When Developing Software For Use In The Medical Domain, Martin Mchugh, Fergal Mccaffery, Valentine Casey

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Non-safety critical software developers have been reaping the benefits of adopting agile practices for a number of years. However, developers of safety critical software often have concerns about adopting agile practices. Through performing a literature review, this research has identified the perceived barriers to following agile practices when developing medical device software. A questionnaire based survey was also conducted with medical device software developers in Ireland to determine the barriers to adopting agile practices. The survey revealed that half of the respondents develop software in accordance with a plan driven software development lifecycle and that they believe that there are …

Economic, Energy And Ghg Emissions Performance Evaluation Of A Whispergen Mk Iv Stirling Engine Μ-Chp Unit In A Domestic Dwelling, Gerry Conroy, Aidan Duffy, Lacour Ayompe

Articles

This paper presents an assessment of the energy, economic and greenhouse gas emissions performances of a WhisperGen Mk IV Stirling engine μ-CHP unit for use in a conventional house in the Republic of Ireland. The energy performance data used in this study was obtained from a field trial carried out in Belfast, Northern Ireland during the period June 2004 - July 2005 by Northern Ireland Electricity and Phoenix Gas working in collaboration with Whispertech UK. A comparative performance analysis between the µ-CHP unit and a condensing gas boiler revealed that the µ-CHP unit resulted in an annual cost saving of …

Microfiber Coupler Based Label-Free Immunosensor, Lin Bo, Christy Charlton O'Mahony, Yuliya Semenova, Niamh Gilmartin, Pengfei Wang, Gerald Farrell

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Optical microfibers and related structures which incorporate large evanescent field and minimal size offer new opportunities for biosensing applications. In this paper we report the development of an immunosensor based on a tapered microfiber coupler embedded in a low refractive index polymer. Biomolecules adsorbed on the microfiber coupler surface modify the surrounding refractive index. By immobilizing antigens on the surface of the sensing area, the microfiber coupler was able to operate as a label-free immunosensor to detect specific antibodies. We experimentally demonstrated for the first time the sensing ability of this sensor using a fibrinogen antigen-antibody pair. By monitoring the …

Improved Protocols For Vibrational Spectroscopic Analysis Of Body Fluids, Franck Bonnier, François Petitjean, Matthew Baker, Hugh Byrne

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The applications of vibrational spectroscopy to the examination of human blood serum are explored. Although FTIR spectra can be recorded in aqueous solutions at (gelatin) concentrations as low as 100mg/L, the high-wavenumber region remains obscured by water absorption. Using Raman spectroscopy, high quality spectra of gelatine solutions as low as 10mg/L can be achieved, also covering the high-wavenumber regions. In human serum, spectral profiles are weak and partially obscured by water features. Dried deposits are shown to be physically and chemically inhomogeneous resulting in reduced measurement reproducibility. Concentration of the serum using commercially available centrifugal filter devices results in an …

In-Package Atmospheric Pressure Cold Plasma Treatment Of Cherry Tomatoes, N. Misra, Kevin Keener, Paula Bourke, J Mosnier, Patrick Cullen

Articles

Cold plasma is increasingly under research for decontamination of foods, especially fresh fruits and vegetables. The effect of cold plasma on food quality, however, remains under researched. This study investigates the effects of cold plasma generated within a sealed package from a dielectric barrier discharge on the physical quality parameters and respiration rates of cherry tomatoes. Respiration rates and weight loss were monitored continuously, while other parameters are reported at the end of storage period. Differences among weight loss, pH and firmness for control and treated cherry tomatoes were insignificant towards the end of storage life. Changes in respiration rates …

Investigating Automatic Measurements Of Prosodic Accommodation And Its Dynamics In Social Interaction, Celine De Looze, Stefan Scherer, Brian Vaughan, Nick Campbell

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Spoken dialogue systems are increasingly being used to facilitate and enhance human communication. While these interactive systems can process the linguistic aspects of human communication, they are not yet capable of processing the complex dynamics involved in social interaction, such as the adaptation on the part of interlocutors. Providing interactive systems with the capacity to process and exhibit this accommodation could however improve their efficiency and make machines more socially-competent interactants.

At present, no automatic system is available to process prosodic accommodation, nor do any clear measures exist that quantify its dynamic manifestation. While it can be observed to be …

In-Package Atmospheric Pressure Cold Plasma Treatment Of Strawberries, N. Misra, Paula Bourke, Patrick Cullen, Sonal Patil

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The ability to generate low temperature plasma at atmospheric pressure offers new opportunities to decontaminate biological materials, including fresh foods. In this study, strawberries were treated with atmospheric cold plasma (ACP), generated with a 60 kV dielectric barrier discharge (DBD) pulsed at 50 Hz, across a 40 mm electrode gap, generated inside a sealed package containing ambient air (42% relative humidity). The current-voltage characteristics revealed that the plasma operated in the filamentary regime. The background microflora (aerobic mesophillic bacteria, yeast and mould) of strawberries treated for 5 min was reduced by 2 log 10 within 24 h of post-ACP treatment. …

Using Acrylamide Based Photopolymers For Fabrication Of Holographic Optical Elements In Solar Energy Applications, Hoda Akbari, Izabela Naydenova, Suzanne Martin

Articles

A holographic device is under development that aims to improve light collection in solar cells. The aim is to explore the potential of using photopolymer Holographic Optical Elements (HOE) to collect light from a moving source, such as the sun, and re-direct it for concentration by a holographic lens.. A working range of 45 degrees is targeted for such a device to be useful in solar applications without tracking. A photopolymer HOE is capable of efficiently re-directing light, but the angular selectivity of a single grating is usually of the order of one degree at the thicknesses required for high …

In-Package Nonthermal Plasma Degradation Of Pesticides On Fresh Produce, N. Misra, Shashi Pankaj, Tony Walsh, Finbarr O'Regan, Paula Bourke, Patrick Cullen

Articles

In-package nonthermal plasma (NTP) technology is a novel technology for the decontamination of foods and biological materials. This study presents the first report on the potential of the technology for the degradation of pesticide residues. A cocktail of pesticides, namely Azoxystrobin, Cyprodinil, Fludioxonil and Pyriproxyfen was tested on strawberries. The concentrations of these pesticides were monitored in priori and post- plasma treatment using GC-MS/MS. An applied voltage and time dependent degradation of the pesticides was observed for treatment voltages of 60, 70 and 80 kV and treatment durations ranging from 1 to 5 min, followed by 24 h in-pack storage. …

Photocatalytic Activity Indicator Inks For Probing A Wide Range Of Surfaces, Suresh Pillai, Andrew Mills, James Hepburn, David Hazafy, Christopher O'Rourke, Nathan Wells, Josef Krysa, Michal Baudys, Martin Zlamal, Hana Bartkova, Claire E. Hill, Kim R. Winn, Morten E. Simonsen, Erik G. Sogaard, Swagata Banerjee, Rachel Fagan

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Three photocatalyst inks based on the redox dyes, Resazurin (Rz), Basic Blue 66 (BB66) and Acid Violet 7 (AV7, are used to assess the photocatalytic activities of a variety of different materials, such as commercial paint, tiles and glass and laboratory made samples of sol-gel coated glass and paint, which collectively exhibit a wide range of activities that cannot currently be probed by any one of the existing ISO tests. Unlike the ISO tests, the ink tests are fast (typically < 10 min), simple to employ and inexpensive. Previous work indicates that the Rz ink test at least correlates linearly with other photocatalytic tests such as the photomineralisation of stearic acid. The average time to bleach 90% of the key RGB colour component of the ink (red for Rz and BB66 inks) and green for AV7 ink) is determined, ttb(90), for eight samples of each of the different materials tested. Five laboratories conducted the tests and the results revealed an average repeatability and reproducibility of: ca. 11% and ca 21%, respectively, which compare well with those reported for the current ISO tests. Additional work on commercial self-cleaning glass using an Rz ink showed that the change in the red component of the RGB image of the ink correlated linearly with that of the change of absorbance (at 608 nm) (as measured using UV/Vis spectroscopy) and the change in the a* component of the Lab colour analysis of the ink, as measured using diffuse reflectance spectroscopy. As a consequence, all three methods generate the same ttb(90). The advantages of the RGB digital image analysis method are discussed briefly.

Resilient Digital Image Watermarking For Document Authentication, Jonathan Blackledge, Oleksandr Iakovenko

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Abstract—We consider the applications of the Discrete Cosine Transform (DCT) and then a Chirp coding method for producing a highly robust system for watermarking images using a block partitioning approach subject to a self-alignment strategy and bit error correction. The applications for the algorithms presented and the system developed include the copyright protection of images and Digital Right Management for image libraries, for example. However, the principal focus of the research reported in this paper is on the use of printscan and e-display-scan image authentication for use in e-tickets where QR code, for example, are embedded in a full colour …

H-Index For Quantifying The Fractal Or Scaling Structure Of Geographic Features, Bin Jiang, Junjun Yin

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Although geographic features, such as mountains and coastlines, are fractal, some studies have claimed that the fractal property is not universal. This claim, which is dubious, is mainly attributed to the strict definition of fractal dimension as a measure or index for characterizing the complexity of fractals. In this article, we propose an alternative, ht-index, to quantify the fractal or scaling structure of geographic features. A geographic feature has ht-index (h) if the pattern of far more small things than large ones recurs (h – 1) times at different scales. The higher the ht-index, the more complex …