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Articles 91 - 120 of 367
Full-Text Articles in Physics
Concentric Double Hollow Grid Cathode Discharges, C. T. Teodorescu-Soare, S. A. Irimiciuc, C. Ionita, D. G. Dimitriu, B. Hodoroaba, T. O'Hara, O. Vasilovici, L. Amarandi, R. W. Schrittwieser
Concentric Double Hollow Grid Cathode Discharges, C. T. Teodorescu-Soare, S. A. Irimiciuc, C. Ionita, D. G. Dimitriu, B. Hodoroaba, T. O'Hara, O. Vasilovici, L. Amarandi, R. W. Schrittwieser
Articles
A new cathode system, consisting of two concentric spherical hollow grids with two aligned orifices, is investigated by space-resolved Langmuir probe measurements and non-linear dynamics analysis. Negative biases of this spherical hollow grids arrangement lead to the formation of two complex space charge structures in the regions of the orifices. The overall dynamics of the current-voltage characteristic (I–V characteristic) of each discharge is characterized by strong oscillatory behaviour with various waveforms correlated with jumps in the static I–V characteristics. Space-resolved measurements through the two aligned orifices of the two grids show a peak increase of the electron temperature and particle …
Relationship Of Ndvi And Oak (Quercus)Pollen Including A Predictive Model In The Sw Mediterranean Region, Rocío González-Naharro, Elia Quirós, Santiago Fernández-Rodríguez, Inmaculada Silva-Palacios, J. M. Maya-Manzano, Rafael Tormo-Molina, Raúl Pecero-Casimiro, Alejandro Monroy-Colin, Ángela Gonzalo-Garijo
Relationship Of Ndvi And Oak (Quercus)Pollen Including A Predictive Model In The Sw Mediterranean Region, Rocío González-Naharro, Elia Quirós, Santiago Fernández-Rodríguez, Inmaculada Silva-Palacios, J. M. Maya-Manzano, Rafael Tormo-Molina, Raúl Pecero-Casimiro, Alejandro Monroy-Colin, Ángela Gonzalo-Garijo
Articles
Techniques of remote sensing are being used to develop phenological studies. Our goal is to study the correlation among the Normalized Difference Vegetation Index (NDVI) related with oak trees included in three set data polygons (15, 25 and 50 km to aerobiological sampling point as NDVI-15, 25 and 50), and oak (Quercus) daily average pollen counts from 1994 to 2013. The study was developed in the SW Mediterranean region with continuous pollen recording within the mean pollen season of each studied year. These pollen concentrations were compared with NDVI values in the locations containing the vegetation under a study based …
Magnetic Field Sensor Based On A Tri-Microfiber Coupler Ring In Magnetic Fluid And A Fiber Bragg Grating, Fangfang Wei, Dejun Liu, Arun Kumar Mallik, Gerald Farrell, Qiang Wu, Gang-Ding Peng, Yuliya Semenova
Magnetic Field Sensor Based On A Tri-Microfiber Coupler Ring In Magnetic Fluid And A Fiber Bragg Grating, Fangfang Wei, Dejun Liu, Arun Kumar Mallik, Gerald Farrell, Qiang Wu, Gang-Ding Peng, Yuliya Semenova
Articles
In this paper we propose and investigate a novel magnetic field sensor based on a Tri-microfiber coupler combined with magnetic fluid and a fiber Bragg grating (FBG) in a ring. A sensitivity of 1306 pm/mT was experimentally demonstrated in the range of magnetic fields from 0 to 15 mT. The reflection peak in the output spectrum associated with the FBG serves as a reference point allowing to avoid ambiguity in determining the spectral shift induced by the magnetic field. Due to its high sensitivity at low magnetic fields, the proposed structure could be of high interest in low field biosensing …
Exploring Subcellular Responses Of Prostate Cancer Cells To X-Ray Exposure By Raman Mapping, Maciej Roman, Agnieszka Panek, Hugh Byrne, Tomasz P Wrobel, Esen Efeoglu, Czeslawa Paluszkiewicz, Wojciech Maria Kwiatek
Exploring Subcellular Responses Of Prostate Cancer Cells To X-Ray Exposure By Raman Mapping, Maciej Roman, Agnieszka Panek, Hugh Byrne, Tomasz P Wrobel, Esen Efeoglu, Czeslawa Paluszkiewicz, Wojciech Maria Kwiatek
Articles
Understanding the response of cancer cells to ionising radiation is a crucial step in modern radiotherapy. Raman microspectroscopy, together with Partial Least Squares Regression (PLSR) analysis has been shown to be a powerful tool for monitoring biochemical changes of irradiated cells on the subcellular level. However, to date, the majority of Raman studies have been performed using a single spectrum per cell, giving a limited view of the total biochemical response of the cell. In the current study, Raman mapping of the whole cell area was undertaken to ensure a more comprehensive understanding of the changes induced by X-ray radiation. …
Vacuum Polarization For Varying Quantum Scalar Field Parameters In Schwarzschild–Anti–De Sitter Spacetime, Cormac Breen, Peter Taylor
Vacuum Polarization For Varying Quantum Scalar Field Parameters In Schwarzschild–Anti–De Sitter Spacetime, Cormac Breen, Peter Taylor
Articles
Equipped with new powerful and efficient methods for computing quantum expectation values in static-spherically symmetric spacetimes in arbitrary dimensions, we perform an in-depth investigation of how the quantum vacuum polarization varies with the parameters in the theory. In particular, we compute and compare the vacuum polarization for a quantum scalar field in the Schwarzschild–anti–de Sitter black hole spacetime for a range of values of the field mass and field coupling constant as well as the black hole mass and number of spacetime dimensions. In addition, a new approximation for the vacuum polarization in asymptotically anti–de Sitter black hole spacetimes is …
Raman Spectroscopy Detects Biochemical Changes Due To Different Cell Culture Environments In Live Cells In Vitro, Mahmoud Gargotti, Esen Efeoglu, Hugh Byrne, Alan Casey
Raman Spectroscopy Detects Biochemical Changes Due To Different Cell Culture Environments In Live Cells In Vitro, Mahmoud Gargotti, Esen Efeoglu, Hugh Byrne, Alan Casey
Articles
The in vitro cell culture environment can impact on cell biochemistry and cell cycle. The manifestation of such substrate-induced changes in cell cycle in the Raman microspectroscopic profiles of cell cultures is investigated at the level of nucleolus, nucleus and cytoplasm. HeLa immortalised human cervical cells and HaCaT dermal cells were cultured on three different substrates, conventional polystyrene cell culture dishes, CaF2 slides as a commonly used Raman substrate, and glass slides coated with Collagen Rat Tail, as a mimic of the extra cellular matrix (ECM) environment. A cell cycle study, based on percentage DNA content, as determined using Propidium …
Serialised Holography For Brand Protection And Authentication, Dinesh Vather, Izabela Naydenova, Dervil Cody, Monika Zawadzka, Suzanne Martin, Emilia Mihaylova, Stephen Curran, Paul Duffy, Josune Portillo, Daniel Connell, Stephen Mcdonnell, Vincent Toal
Serialised Holography For Brand Protection And Authentication, Dinesh Vather, Izabela Naydenova, Dervil Cody, Monika Zawadzka, Suzanne Martin, Emilia Mihaylova, Stephen Curran, Paul Duffy, Josune Portillo, Daniel Connell, Stephen Mcdonnell, Vincent Toal
Articles
The problems presented by counterfeit products and documentation are discussed. Limitations of existing holograms for anti-counterfeit applications are described. We describe the advantages of full holographic serialisation and the requirements in terms of materials and techniques for mass production of true serialised holograms. These requirements having been met, we report for the first time the mass production of fully serialised holograms. The novelty of approach consists of the direct use of product manufacturer’s information as the object in a holographic recording system along with a self-processing photopolymer and modular optical system to facilitate mass production of truly serialised volume holograms. …
Multicomponent Analysis Using A Confocal Raman Microscope, Zhengyuan Tang, Sinead J. Barton, Thomas E. Ward, John P. Lowry, Michelle M. Doran, Hugh Byrne, Bryan M. Hennelly
Multicomponent Analysis Using A Confocal Raman Microscope, Zhengyuan Tang, Sinead J. Barton, Thomas E. Ward, John P. Lowry, Michelle M. Doran, Hugh Byrne, Bryan M. Hennelly
Articles
Measuring the concentration of multiple chemical components in a low volume aqueous mixture by Raman spectroscopy has received significant interest in the literature. All of the contributions to date focus on the design of optical systems that facilitate the recording of spectra with high signal-to-noise ratio, by collecting as many Raman scattered photons as possible. In this study, the confocal Raman microscope set-up is investigated for multicomponent analysis. Partial Least Squares Regression is used to quantify physiologically relevant aqueous mixtures of glucose, lactic acid, and urea. The predicted error is 17.81 mg/dL for glucose, 10.6 mg/dL for lactic acid and …
Advancing Raman Microspectroscopy For Cellular And Subcellular Analysis: Towards In Vitro High Content Spectralomic Analysis, Hugh Byrne, Franck Bonnier, Alan Casey, Marcus Maher, Jennifer Mcintyre, Esen Efeoglu, Zeineb Farhane
Advancing Raman Microspectroscopy For Cellular And Subcellular Analysis: Towards In Vitro High Content Spectralomic Analysis, Hugh Byrne, Franck Bonnier, Alan Casey, Marcus Maher, Jennifer Mcintyre, Esen Efeoglu, Zeineb Farhane
Articles
In the confocal mode, Raman microspectroscopy can profile the biochemical content of biological cells at a subcellular level, and any changes to it by exogenous agents, such as therapeutic drugs or toxicants. As an exploration of the potential of the technique as a high content, label free analysis technique, this report reviews work to monitor the spectroscopic signatures associated with the uptake and response pathways of commercial chemotherapeutic agents and polymeric nanoparticles by human lung cells. It is demonstrated that the signatures are reproducible and characteristic of the cellular event, and can be used, for example, to identify the mode …
Raman Spectral Analysis For Rapid Screening Of Dengue Infection, Tahir Mahmood, Haq Nawaz, A. Ditta, M.I. Majeed, M.A. Hanif, N. Rashid, H.N. Bhatti, H.F. Nargis, M. Saleem, Franck Bonnier, Hugh Byrne
Raman Spectral Analysis For Rapid Screening Of Dengue Infection, Tahir Mahmood, Haq Nawaz, A. Ditta, M.I. Majeed, M.A. Hanif, N. Rashid, H.N. Bhatti, H.F. Nargis, M. Saleem, Franck Bonnier, Hugh Byrne
Articles
Infection with the dengue virus is currently clinically detected according to different biomarkers in human blood plasma, commonly measured by enzyme linked immunosorbent assays, including non-structural proteins (Ns1), immunoglobulin M (IgM) and immunoglobulin G (IgG). However, there is little or no mutual correlation between the biomarkers, as demonstrated in this study by a comparison of their levels in samples from 17 patients. As an alternative, the label free, rapid screening technique, Raman spectroscopy has been used for the characterisation/diagnosis of healthy and dengue infected human blood plasma samples. In dengue positive samples, changes in specific Raman spectral bands associated with …
Holographic Beam-Shaping Diffractive Diffusers Fabricated By Using Controlled Laser Speckle, Kevin Murphy, Vincent Toal, Izabela Naydenova, Suzanne Martin
Holographic Beam-Shaping Diffractive Diffusers Fabricated By Using Controlled Laser Speckle, Kevin Murphy, Vincent Toal, Izabela Naydenova, Suzanne Martin
Articles
A method for fabricating diffractive holographic optical diffusers is reported, allowing a high degree of control of the resulting diffuser characteristics. The method consists of recording a laser speckle pattern using a single carrier beam, with controlled speckle size and shape, in an acrylamide-based volume photopolymer. The multiple interferences that create the speckle pattern form the hologram. Results are presented verifying the diffusers are volume holographic in nature and the speckle pattern is recorded accurately in the photopolymer. Diffusers recorded by this method are analysed to characterise the optical performance of the diffusers and to illustrate their beam-shaping capabilities, particularly …
Studies Of Geometrical Profiling In Fabricated Tapered Optical Fbers Using Whispering Gallery Modes Spectroscopy, Vishnu Kavungal, Gerald Farrell, Qiang Wu, Arun Kumar Mallik, Yuliya Semenova
Studies Of Geometrical Profiling In Fabricated Tapered Optical Fbers Using Whispering Gallery Modes Spectroscopy, Vishnu Kavungal, Gerald Farrell, Qiang Wu, Arun Kumar Mallik, Yuliya Semenova
Articles
This paper experimentally demonstrates a method for geometrical profiling of asymmetries in fabricated thin microfiber tapers with waist diameters ranging from ∼10 to ∼50µm with submicron accuracy. The method is based on the analysis of whispering gallery mode resonances excited in cylindrical fiber resonators as a result of evanescent coupling of light propagating through the fiber taper. The submicron accuracy of the proposed method has been verified by SEM studies. The method can be applied as a quality control tool in fabrication of microfiber based devices and sensors or for fine-tuning of microfiber fabrication set-ups.
Investigation Of Temperature Response Of Photopolymer Material Used For Holographic Sensor, Muhammad Irfan Dr, Tatsiana Mikulchyk Dr, Suzanne Martin Dr, Izabela Naydenova Prof
Investigation Of Temperature Response Of Photopolymer Material Used For Holographic Sensor, Muhammad Irfan Dr, Tatsiana Mikulchyk Dr, Suzanne Martin Dr, Izabela Naydenova Prof
Articles
Recently, functionalised photopolymer has emerged as a versatile recording material in the field of optical holography due to its novel characteristics and potential use in the development of holographic based sensors, and optical elements. This work describes the temperature response of a newly developed photopolymer, containing of a monomer Nisopropylacrylamide (NIPA) which under photopolymerisation forms a temperature sensitive polymer - Poly(Nisopropylacrylamide) (PNIPA). The photonic sensor was developed by holographic recording of volume phase transmission gratings in a self-processing NIPA-based polymer with a 532 nm laser beam. A 633 nm probe beam was used to monitor real time diffraction efficiency (DE) …
K-Means And Hierarchical Cluster Analysis As Segmentation Algorithms Of Ftir Hyperspectral Images Collected From Cutaneous Tissue, Cassio Lima, Luciana Correa, Hugh Byrne, Denise Zezell
K-Means And Hierarchical Cluster Analysis As Segmentation Algorithms Of Ftir Hyperspectral Images Collected From Cutaneous Tissue, Cassio Lima, Luciana Correa, Hugh Byrne, Denise Zezell
Articles
Fourier Transform Infrared (FTIR) spectroscopy is a rapid and label-free analytical technique whose potential as a diagnostic tool has been well demonstrated. The combination of spectroscopy and microscopy technologies enable wide-field scanning of a sample, providing a hyperspectral image with tens of thousands of spectra in a few minutes. In order to increase the information content of FTIR images, different clustering algorithms have been proposed as segmentation methods. However, systematic comparative tests of these techniques are still missing. Thus, the present paper aims to compare the ability of K-means Cluster Analysis (KMCA) and Hierarchical Cluster Analysis (HCA) as clustering algorithms …
High Sensitivity Temperature Sensor Based On Singlemode-No-Core- Singlemode Fibre Structure And Alcohol, Ke Tiana, Gerald Farrell, Xianfan Wang, Yifan Xin, Yanqiu Du, Wenlei Yang, Haidong Liang, Elfed Lewis, Pengfei Wang
High Sensitivity Temperature Sensor Based On Singlemode-No-Core- Singlemode Fibre Structure And Alcohol, Ke Tiana, Gerald Farrell, Xianfan Wang, Yifan Xin, Yanqiu Du, Wenlei Yang, Haidong Liang, Elfed Lewis, Pengfei Wang
Articles
A high sensitivity temperature sensor based on a singlemode-no-core-singlemode (SNCS) fibre structure and surrounded with alcohol within a silica capillary is described. In this investigation, no-core fibre (NCF) is used as the multimode waveguide and alcohol is chosen as the temperature sensitive medium. By packaging the alcohol solution with a short length of NCF enclosed within a silica capillary, the surrounding temperature can be detected by monitoring the variations of transmission loss at a specific wavelength. The theoretical analysis predicts this temperature sensor can provide high sensitivity, and the experimental results support this. The maximum temperature sensitivity of the sample …
Nano–Bio Interactions: Nanomedicine And Nanotoxicology, Hugh Byrne, S. Mukherjee, Pratap C. Naha
Nano–Bio Interactions: Nanomedicine And Nanotoxicology, Hugh Byrne, S. Mukherjee, Pratap C. Naha
Articles
The 21st century has truly become the age of nanotechnology. Nanomaterials, design strategies, and processing have already made a significant impact in areas of materials science and electronics, with many commercial applications already being available on the consumer market. However, the ability to manipulate material functions and interactions on a scale of tens of nanometers, e.g., biological subcellular organelles, may yet prove to have the most significant impact on human health and the environment.
Development Of A Photopolymer Holographic Lens For Collimation Of Light From A Green Light-Emitting Diode, Sanjay Keshri, Kevin Murphy, Vincent Toal, Izabela Naydenova, Suzanne Martin
Development Of A Photopolymer Holographic Lens For Collimation Of Light From A Green Light-Emitting Diode, Sanjay Keshri, Kevin Murphy, Vincent Toal, Izabela Naydenova, Suzanne Martin
Articles
A holographic optical element (HOE) was developed to collimate a monochromatic light-emitting diode (LED). The fabrication was achieved by the interference of collimated and diverging beams from a 532 nm laser to produce the required photonic structure in a self-developing photopolymer material. The experimental values of diffraction efficiency and spatial period across the HOE were compared with their expected theoretical values. Good agreement was found for the spatial period; however, the diffraction efficiency varied significantly across the lens. In this paper, two approaches have been taken to address this variation: (1) modification of recording geometry and (2) optimization of recording …
Spectroscopic Study Of Excited Molecular Nitrogen Generation Due To Interactions Of Metastable Noble Gas Atoms, Laurence Scally, James Lalor, Miroslav Gulan, Patrick J. Cullen, Vladimir Milosavljevic
Spectroscopic Study Of Excited Molecular Nitrogen Generation Due To Interactions Of Metastable Noble Gas Atoms, Laurence Scally, James Lalor, Miroslav Gulan, Patrick J. Cullen, Vladimir Milosavljevic
Articles
This work provides an insight into the generation of excited nitrogen species by allowing noble gases to interact both with one another and ambient air. He and Ar were utilized to generate the optimum selectivity process to create reactive nitrogen species. An optimum setting for the generation of excited molecular nitrogen species, based on their excited energy levels, was obtained when using a mixture of Ar-He at a ratio of 10:1. At that point, when a voltage of 27 kV is applied to the system, it reached the maximum efficiency for selectivity processes to occur which allowed for a greater …
Robust, Bridge-Less Ion-Selective Electrodes With Significantly Reduced Need For Pre- And Post-Application Handling, Benjamin Schazmann, S. Demey, Z. Waqar Ali, M-S Plissart, E. Brennan, A. Radu
Robust, Bridge-Less Ion-Selective Electrodes With Significantly Reduced Need For Pre- And Post-Application Handling, Benjamin Schazmann, S. Demey, Z. Waqar Ali, M-S Plissart, E. Brennan, A. Radu
Articles
We are demonstrating robust, single-layer ion-selective electrode (ISE) utilizing simple Ag/AgCl electrode as solid support without the need for intermediate polymer layer. We have created and chemically linked a family of imidazolium ionic liquids (ILs) with poly (vinyl chloride) (PVC) using click chemistry, resulting in hybrid materials with tunable characteristics. The resultant material inherently contains chloride ion thus offering the ability to stabilize interfacial potential. This allowed us to construct very simple, single-layer membranes with significantly reduced need for conditioning as an added bonus compared to traditional sensors. Chemical immobilization of ISE membrane components also led to extended lifetime as …
Theoretical Modeling And Design Of Photonic Structures In Zeolite Nanocomposites For Gas Sensing. Part Ii: Volume Gratings, Dervil Cody, Izabela Naydenova
Theoretical Modeling And Design Of Photonic Structures In Zeolite Nanocomposites For Gas Sensing. Part Ii: Volume Gratings, Dervil Cody, Izabela Naydenova
Articles
The suitability of holographic structures fabricated in zeolite nanoparticle-polymer composite materials for gas sensing applications has been investigated. Theoretical modelling of the sensor response (i.e. change in hologram readout due to a change in refractive index modulation or thickness as a result of gas adsorption) of different sensor designs was carried out using Raman-Nath theory and Kogelnik’s Coupled Wave Theory. The influence of a range of parameters on the sensitivity of holographically-recorded surface and volume photonic structures has been studied, namely hologram geometry, hologram thickness and spatial frequency, reconstruction wavelength, and zeolite nanoparticle refractive index. From this, the optimum fabrication …
Self-Processing Photopolymer Materials For Versatile Design And Fabrication Of Holographic Sensors And Interactive Holograms, Dervil Cody, Sabad-E Gul, Tatsiana Mikulchyk, Muhammad Irfan, Anastasia Kharchenko, Kamila Goldyn, Suzanne Martin, Svetlana Mintova, John Cassidy, Izabela Naydenova
Self-Processing Photopolymer Materials For Versatile Design And Fabrication Of Holographic Sensors And Interactive Holograms, Dervil Cody, Sabad-E Gul, Tatsiana Mikulchyk, Muhammad Irfan, Anastasia Kharchenko, Kamila Goldyn, Suzanne Martin, Svetlana Mintova, John Cassidy, Izabela Naydenova
Articles
The aim of this paper is to discuss the benefits as well as the limitations of utilizing photopolymer materials in the design of holograms that are responsive to changes in their environment, such as changes in the concentration of a specific substance, temperature, and pressure. Three different case studies are presented, including both surface and volume phase holograms, in order to demonstrate the flexibility in the approach of utilizing holographic photopolymers for the design of sensors and interactive optical devices. First, a functionalized surface relief hologram is demonstrated to operate as an optical sensor for the detection of metal ions …
Singlemode-Multimode-Singlemode Fibre Structure For Phase Transition Monitoring In Phase Changing Materials, Rahul Kumar, Wei Han, Dejun Liu, Wai Pang Ng, Richard Binns, Krishna Busawon, Yong Qing Fu, Zabih Ghassemlooy, Christopher Underwood, Khamid Mahkmov, Jinhui Yuan, Chongxiu Yu, Huazhong Shu, Xing Ao Li, Tuan Guo, Gerald Farrell, Yuliya Semenova, Qiang Wu Prof.
Singlemode-Multimode-Singlemode Fibre Structure For Phase Transition Monitoring In Phase Changing Materials, Rahul Kumar, Wei Han, Dejun Liu, Wai Pang Ng, Richard Binns, Krishna Busawon, Yong Qing Fu, Zabih Ghassemlooy, Christopher Underwood, Khamid Mahkmov, Jinhui Yuan, Chongxiu Yu, Huazhong Shu, Xing Ao Li, Tuan Guo, Gerald Farrell, Yuliya Semenova, Qiang Wu Prof.
Articles
Abstract. A platinum-coated singlemode-multimode structure is investigated in this paper as an optical fibre sensor (OFS) to monitor the phase transition of a phase change material (PCM). Paraffin wax has been used as an example to demonstrate the sensor’s performance and operation. Most materials have the same temperature but different thermal energy levels during the phase change process, therefore, sole dependency on temperature measurement may lead to an incorrect estimation of the stored energy in PCM. The output spectrum of the reflected light from the OFS is very sensitive to the bend introduced by the PCM where both liquid and …
Optical Fiber Fresnel Reflection Sensor For Direct Detection Of The Solid-Liquid Phase Change In N-Octadecane, Wei Han, Marek Rebow, Dejun Liu, Gerald Farrell, Yuliya Semenova, Qiang Wu
Optical Fiber Fresnel Reflection Sensor For Direct Detection Of The Solid-Liquid Phase Change In N-Octadecane, Wei Han, Marek Rebow, Dejun Liu, Gerald Farrell, Yuliya Semenova, Qiang Wu
Articles
An all optical fiber Fresnel reflection sensor for detecting the solid–liquid phase change in n-octadecane is proposed and experimentally demonstrated. The sensor probe consists of a single-mode fiber with a cleaved end which is immersed in the material sample under test. As the n-octadecane changes from solid to liquid or from liquid to solid, its refractive index (RI) changes resulting in changes of the light power ratio reflected by the probe. Since the RI of n-octadecane during its phase transition changes discontinuously, inflection in the reflected light power ratio dependence indicates the phase change of the sample in the vicinity …
Enabling Quantification Of Protein Concentration In Human Serum Biopsies Using Attenuated Total Reflectance – Fourier Transform Infrared (Atr-Ftir) Spectroscopy, Kate Spalding, Franck Bonnier, Clément Bruno, Hélène Blasco, Ruth E. Board, Isabelle Benz-De-Bretagne, Hugh Byrne, Holly J. Butler, Igor Chourpa, Pretheepan Radhakrishnan, Matthew J. Baker
Enabling Quantification Of Protein Concentration In Human Serum Biopsies Using Attenuated Total Reflectance – Fourier Transform Infrared (Atr-Ftir) Spectroscopy, Kate Spalding, Franck Bonnier, Clément Bruno, Hélène Blasco, Ruth E. Board, Isabelle Benz-De-Bretagne, Hugh Byrne, Holly J. Butler, Igor Chourpa, Pretheepan Radhakrishnan, Matthew J. Baker
Articles
Changes in protein concentrations within human blood are used as an indicator for nutritional state, hydration and underlying illnesses. They are often measured at regular clinical appointments and the current analytical process can result in long waiting times for results and the need for return patient visits. Attenuated total reflectance – Fourier transform infrared (ATR-FTIR) spectroscopy has the ability to detect minor molecular differences, qualitatively and quantitatively, in biofluid samples, without extensive sample preparation. ATR-FTIR can return an analytical measurement almost instantaneously and therefore could be deemed as an ideal technique for monitoring molecular alterations in blood within the clinic. …
Application Of Box-Behnken Experimental Design For The Formulation And Optimisation Of Selenomethionine-Loaded Chitosan Nanoparticles Coated With Zein For Oral Delivery., Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Minna Khalid Danish, Sinéad M. Ryan
Application Of Box-Behnken Experimental Design For The Formulation And Optimisation Of Selenomethionine-Loaded Chitosan Nanoparticles Coated With Zein For Oral Delivery., Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Minna Khalid Danish, Sinéad M. Ryan
Articles
Selenomethionine is an essential amino acid with a narrow therapeutic index and susceptibility to oxidation. Here it was encapsulated into a nanoparticle composed of chitosan cross-linked with tripolyphosphate for oral delivery. The formulation was optimised using a three-factor Box-Behnken experimental design. The chitosan:tripolyphosphate ratio, chitosan solvent pH, and drug load concentration were independently varied. The dependent variables studied were encapsulation efficiency, particle size, polydispersity index and zeta potential. For optimisation, encapsulation efficiency and zeta potential were maximised, particle diameter was set to 300 nm and polydispersity index was minimised. A 0.15 mg/mL concentration of selenomethionine, chitosan solvent pH of 3, …
Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Doran
Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Doran
Articles
We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method, we …
A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond
A Mathematical Analysis Of Drug Dissolution In The Usp Flow Through Apparatus, David Mcdonnell, Deirdre M. D'Arcy, Lawrence J. Crane, Brendan Redmond
Articles
This paper applies boundary layer theory to the process of drug dissolution in the USP (United States Pharmacopeia) Flow Through Apparatus. The mass transfer rate from the vertical planar surface of a compact within the device is examined. The theoretical results obtained are then compared with those of experiment. The paper also examines the effect on the dissolution process caused by the interaction between natural and forced convection within the apparatus and the introduction of additional boundaries.
The Evaluation Of The Effect Of Strain Limits On The Physical Properties Of Magnetorheological Elastomers Subjected To Uniaxial And Biaxial Cyclic Testing., Dave Gorman, Niall Murphy, Ray Ekins, Stephen Jerrams
The Evaluation Of The Effect Of Strain Limits On The Physical Properties Of Magnetorheological Elastomers Subjected To Uniaxial And Biaxial Cyclic Testing., Dave Gorman, Niall Murphy, Ray Ekins, Stephen Jerrams
Articles
Magnetorheological Elastomers (MREs) are “smart” materials whose physical properties are altered by the application of magnetic fields. In a previous study by the authors [1], variations in the physical properties of MREs have been evaluated when subjected to a range of magnetic field strengths for both uniaxial and biaxial cyclic tests. By applying the same magnetic field to similar samples, this paper investigates the effect of both the upper strain limit and the strain amplitude on the properties of MREs subjected to cyclic fatigue testing. As the magnetorheological (MR) effect is due to the dipole-dipole interactions of the …
Formulation, Characterisation And Stability Assessment Of A Food Derived 1 Tripeptide, Leucine-Lysine-Proline Loaded Chitosan Nanoparticles, Minna Khalid Danish, Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Sinead Ryan
Formulation, Characterisation And Stability Assessment Of A Food Derived 1 Tripeptide, Leucine-Lysine-Proline Loaded Chitosan Nanoparticles, Minna Khalid Danish, Giuliana Vozza, Hugh Byrne, Jesus Maria Frias, Sinead Ryan
Articles
The chicken or fish derived tripeptide, Leucine-Lysine-Proline (LKP), inhibits the Angiotensin Converting Enzyme and may be used as an alternative treatment for pre-hypertension. However, it has low permeation across the small intestine. The formulation of LKP into a nanoparticle (NP) has the potential to address this issue. LKP-loaded NPs were produced using an ionotropic gelation technique, using chitosan (CL113). Following optimisation of unloaded NPs, a mixture amount design was constructed using variable concentration of CL113 and tripolyphosphate at a fixed LKP concentration. Resultant particle sizes ranged from 120-271 nm, zeta potential values from 29-37 mV and polydispersity values from 0.3-0.6. …
Ultra-Filtration Of Human Serum For Improved Quantitative Analysis Of Low Molecular Weight Biomarkers Using Atr-Ir Spectroscopy, Franck Bonnier, Luis Felipe Cs. Carvalho, Matthew J. Baker, Hugh Byrne, Igor Chourpa
Ultra-Filtration Of Human Serum For Improved Quantitative Analysis Of Low Molecular Weight Biomarkers Using Atr-Ir Spectroscopy, Franck Bonnier, Luis Felipe Cs. Carvalho, Matthew J. Baker, Hugh Byrne, Igor Chourpa
Articles
Infrared spectroscopy is a reliable, rapid and cost effective characterisation technique, delivering a molecular finger print of the sample. It is expected that its sensitivity would enable detection of small chemical variations in biological samples associated with disease. ATR-IR is particularly suitable for liquid sample analysis and, although air drying is commonly performed before data collection, just a drop of human serum is enough for screening and early diagnosis. However, the dynamic range of constituent biochemical concentrations in the serum composition remains a limiting factor to the reliability of the technique. Using glucose as a model spike in human serum, …