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Wood T.,Royal Military College of Canada | Lewis B.J.,Royal Military College of Canada | Mcdermott K.,Royal Military College of Canada | Bennett L.G.I.,Royal Military College of Canada | And 13 more authors.
Radiation Protection Dosimetry

A reporter molecule consisting of a synthetic oligonucleotide is being characterised for a novel damage detection scenario for its potential use as a field-deployable, personal deoxyribonucleic acid (DNA) dosemeter for radiation detection. This dosemeter is devoid of any biological properties other than being naked DNA and therefore has no DNA repair capabilities. It supports biodosimetry techniques, which require lengthy analysis of cells from irradiated individuals, and improves upon inorganic dosimetry, thereby providing for a more relevant means of measuring the accumulated dose from a potentially mixed-radiation field. Radiation-induced single strand breaks (SSBs) within the DNA result in a quantifiable fluorescent signal. Proof of concept has been achieved over 250 mGy-10 Gy dose range in radiation fields from . 60Co, with similar results seen using a linear accelerator X-ray source. Further refinements to both the molecule and the exposure/detection platform are expected to lead to enhanced levels of detection for mixed-field radiological events. © 2011. Source

Stoeffler K.,Ecole Polytechnique de Montreal | Dubois C.,Ecole Polytechnique de Montreal | Ajji A.,Institute des Materiaux Industriels | Guo N.,Ecole Polytechnique de Montreal | And 2 more authors.
Polymer Engineering and Science

Photonic bandgap Bragg fibers feature periodic sequence of layers of different materials. In those particular waveguides, the wave path is controlled by a periodical spatial modification of the refractive index. Depending on the periodicity of the structure and on the refractive index contrast, a specific wavelength range is propagated along the fiber axis. In this work, we developed all-polymeric photonic bandgap Bragg fibers based on polystyrene (PS)/polymethyl methacrylate (PMMA) alternating layers. We describe a novel and efficient method for the preparation of the fibers preforms, and we present the fibers drawing process and the transmission properties of the resulting Bragg fibers. © 2009 Society of Plastics Engineers. Source

De Moura E.P.,Federal University of Ceara | Normando P.G.,Federal University of Ceara | Goncalves L.L.,Federal University of Ceara | Kruger S.E.,Institute des Materiaux Industriels
Journal of Nondestructive Evaluation

This work aims at evaluating the performance of pattern recognition methods in the identification of different microstructures presented by cast iron, namely, lamellar, vermicular and nodular microstructures, through the statistical fluctuation and fractal analyses of backscattered ultrasonic signals. The signals were obtained with a broad band ultrasonic probe with a central frequency of 5 MHz. The statistical fluctuations of the ultrasonic signals were analyzed by means of Hurst (RSA) and detrended-fluctuation analyses (DFA), and the fractal analyses were carried out by applying the minimal cover and box-counting techniques to the signals. The curves obtained from the statistical fluctuations and fractal analyses, as functions of the time window, were processed by using four pattern classification techniques, namely, principal-component analysis (PCA), Karhunen-Loève transformation (KLT), neural networks and Gaussian classifier. The best results were obtained by Karhunen-Loève expansion and neural networks, where an approximately 100% success rate has been reached for the classification of the different microstructures as well as for the training and the testing sets of events. The results presented correspond to an average taken over 100 randomly chosen sets of events. These results indicate that, within the techniques used, the Karhunen-Loève transformation and neural network associated with the statistical fluctuation analyses (RSA and DFA) are the best tools for the recognition of the different cast iron microstructures. It is worthwhile pointing out that the microstructure classification was made by using backscattering signals acquired during pulse echo ultrasonic nondestructive testing only. Therefore, that approach is a promising method for material characterization. © Springer Science+Business Media, LLC 2011. Source

Azarnoush H.,Institute des Materiaux Industriels | Azarnoush H.,McGill University | Azarnoush H.,Montreal Neurological Institute | Vergnole S.,Institute des Materiaux Industriels | And 5 more authors.
Journal of Biomedical Optics

We explored the potential of intravascular optical coherence tomography (IVOCT) to assess deformation during angioplasty balloon inflation. Using a semi-compliant balloon and artery phantoms, we considered two experimental scenarios. The goal for the first scenario was to investigate if variation in the elasticity of the structure surrounding the balloon could be sensed by IVOCT monitoring. In this scenario, we used three single-layer phantoms with various mechanical properties. Image analysis was performed to extract the inner and outer diameters of the phantoms at various pressures. The goal for the second scenario was twofold. First, we investigated the IVOCT capability to monitor a more complex balloon inflation process. The balloon was in a folded state prior to inflation. This allowed studying two stages of deformation: during balloon unfolding and during balloon expansion. Second, we investigated IVOCT capability to monitor the deformation in a three-layer phantom used to better mimic a true artery. So, not only were the IVOCT images processed to provide the inner and outer diameters of the phantom, but the layer thicknesses were also determined. In both scenarios, IVOCT monitoring revealed to be very efficient in providing relevant information about the phantom deformation during balloon inflation. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Source

Mbeh D.A.,Ecole Polytechnique de Montreal | Franaca R.,Ecole Polytechnique de Montreal | Merhi Y.,Montreal Heart Institute | Zhang X.F.,Institute des Materiaux Industriels | And 3 more authors.
Journal of Biomedical Materials Research - Part A

In the biomedical field, nanomaterials have the potential for use in the targeted delivery of drugs in the human body and in the diagnosis and therapy of certain diseases. In the category of targeted delivery, magnetite (Fe 3O 4) nanoparticles have received much attention. As with any similar new therapy, when such nanoparticles are functionalized with chemical groups designed to permit the specific attachment of drugs, cytotoxicological testing is necessary before moving to animal models. Here, we consider several variously functionalized magnetite nanoparticles, including those prepared with (1) a monolayer of oleic acid (Fe 3O 4@OA), which is subsequently converted to (2) a shell of amine-containing silane (Fe 3O 4@NH 2), (3) a shell of silica (Fe 3O 4@SiO 2), and (4) a shell of amine-containing silane over a shell of silica (Fe 3O 4@SiO 2@NH 2). These latter three functionalities were evaluated for biocompatibility, cellular morphology, mitochondrial function (MTT assay), lactate dehydrogenase membrane leakage (LDH assay), and proinflammatory potential through enzyme linked immunosorbent assay (ELISA) for interleukin 6 (IL-6). Controlled tests were performed over a period of 72 h, with results showing LDH leakage and abnormal Il-6 secretion at high concentrations (>50 μg/mL). The tests showed that, in addition to the surface characteristics of the nanoparticles, both the nutrient medium and the time of suspension before exposure to cells also contribute to nanoparticle cytotoxicity. Copyright © 2012 Wiley Periodicals, Inc. Source

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