The current methodologies in body scanning diagnostic uses different simultaneous imaging modalities like Ultrasound (US), magnetic resonance imaging (MRI), single photon emission tomography (SPECT) and positron emission tomography (PET). The field requires combination of different modalities for effective use in clinical diagnostics. Such incorporation of different modalities has already been achieved. For example, PET-CT hybrid scanner is designed to acquire align functional and anatomical images and recently US-MRI scanner has successfully shown to improve diagnosis of prostate cancer. The non ionizing radiation hybrid US-MRI is of great interest in health care industry. Further these US and MRI modalities uses different contrast agents like micro-sized gas bubbles (MBs) encapsulated by surfactant for US and superparamagnetic nanoparticles for MRI imaging modalities to further enables new diagnostic opportunities and therapeutic applications. Recently in our 3MiCRON project, we have developed the multimodal contrast agent that could be supported for both US and MRI. This was achieved by coating the magnetic nanoparticles to the poly vinyl alcohol (PVA) surfactant shelled MBs. The nanoparticles in the shell effect the structure can alter the MBs performance as an ultrasound contrast agent. The present thesis is conducted to examine the acoustic and mechanical properties of such multimodal contrast agents. These multimodal contrast agents were prepared by coating the surface of PVA-shelled MBs by two following strategies: (1) The superparamagnetic iron oxide (Fe3O4) nano-particles (SPIONs) were chemically anchored to the surface of poly vinyl alcohol (PVA) shelled MBs namely MBs-chem and (2) in the second strategy the SPIONs were physical entrapped into the PVA shell while formation of PVA surface on the gas bubble were named as MBs-phys. To understand the scattering efficiency and viscoelastic properties of these modified agents, we investigated the backscattering power, attenuation coefficient and phase velocity measurements. Our acoustic experimental results indicate that both the modified MBs and non-modified plain PVA-shelled ultrasound contrast agents have the same echogenic response. The investigation of mechanical properties of modified MBs revealed that the attached SPIONs on the PVA shell has reduced the stiffness of MBs-chem shell, while, the SPIONs inside the shell has increased MBs-phys stiffness. As a result, MBs-chem exhibits soft shell behavior under ultrasound exposure than both MBs-phys. Finally, the images were obtained through the MRI investigations at the department of Radiology, Karolinksa Institute, has demonstrated that both MB types have enough magnetic susceptibility that further provides good detectability in vitro and in vivo. As an outlook, the modified magnetic gas bubbles, i.e. both MBs-chem and MBs-phys can be proposed as a potential contrast agent for both US and MR imaging and can be further utilized in potential therapeutic applications. / <p>QC 20131126</p>

O Laboratório de Aplicações Ambientais a Laser, situado no Centro de Lasers e Aplicações no IPEN (Instituto de Pesquisas Energéticas e Nucleares), efetua medidas das concentrações de aerossóis atmosféricos, enviando um feixe de laser à atmosfera e coletando a luz retroespalhada. Tal sistema fornece um grande número de parâmetros físicos que devem ser administrados de forma ágil para a obtenção de análises resultantes. Em conseqüência disso, a implementação de um banco de dados tornou-se imprescindível como instrumento de comunicação e visualização gráfica das medidas coletadas. Um critério de classificação destas valiosas informações foi adotado, estabelecendo níveis de armazenamento definidos a partir de características específicas aos tipos de dados determinados. A compilação e automação destas medidas promoverá a integração entre dados, análise e retorno otimizado de resultados das propriedades da atmosfera, propiciando futuras pesquisas e análise de dados. / The LIDAR system (Light Detection and Ranging) laser remote sensing at the Nuclear and Energy Research Institute Laboratory of Environmental Laser Applications allows on line measurements of variations in the concentrations of atmospheric aerosols by sending a laser beam to the atmosphere and collecting the backscattered light. Such a system supplies a great number of physical parameters that must be managed in an agile form to the attainment of a real time analysis. Database implementation therefore becomes an important toll of communication and graphical visualization of measurements. A criterion for classification of this valuable information was adopted, establishing defined levels of storage from specific characteristics of the determined data types. The compilation and automation of these measurements will promote optimized integration between data, analysis and retrieval of the resulting properties and of the atmosphere, improving future research and data analysis.

>Magister Scientiae - MSc / To study nuclear reactions and nuclear structures, target materials are bombarded with high-energy particles. The target material can either be in a form of a metal film or gas. A target material designed to study certain nuclear reactions or to produce nuclei to study their structure should yield as minimum as possible of competing reactions under ion bombardment. This requires a chemically and isotopically pure target material prepared as a self supporting thin film, or as alternative, prepared on a thin career foil. Additional requirement for lifetime measurement experiments are homogeneity and precise thickness of the target material. Some of the data obtained from the stopping power experiment where targets of 114Cd were used for lifetime measurement are presented. Moreover, a nuclear target should influence the spectroscopic resolution as little as possible. Thus, film thickness must be adjusted to the respective reaction under study while observing the optimum thickness homogeneity.

A review of the main natural dyes (particularly yellow flavonoids and red anthraquinones) and proteinaceous substrates used in Historical Tapestries and North American porcupine quill work was undertaken, and is summarised in Chapter 1. The analysis of natural dyes which have been used on museum artefacts other than textiles has received little systematic study, particularly those of non-European origin. In this research, the use of Ultra Performance Liquid Chromatography (UPLC) for study of natural dyes found on historical textiles and ethnographical objects decorated with porcupine quill work is explored; this required a transfer of existing analytical protocols and methodology. The advantages of using Ultra Performance Liquid Chromatography (UPLC) was evaluated through a method development based on the separation and quantification of ten flavonoid and anthraquinone dyes as described in Chapter 2. These methods were then applied to the characterisation of the dye sources found on a group of sixteenth century historical tapestries which form an important part of the Burrell Collection in Glasgow and are believed to have been manufactured in an English workshop (Chapter 3) and also to the analysis of some late nineteenth century North American porcupine quill work from a collection owned by National Museums Scotland (Chapter 5); allowing exciting conclusions to be drawn in each case about the range of dyestuffs used in their manufacture. The second aim of this research was the development of methodology for the non-invasive quantification of metal ion residues on porcupine quill substrates. This was achieved through a comparative study of reference porcupine quills prepared in-house with dyebaths containing a range of metal ion concentrations (copper and tin). The concentration of metal ions sorbed by the porcupine quills was then quantified with Inductively Coupled Plasma (ICP) coupled to Optical Emission Spectrometry (OES) and non-invasive Particle Induced X-Ray Emission analysis (PIXE) coupled with Rutherford Backscattering Spectrometry (RBS) as described in Chapter 4. The responses provided by the different methods were compared and they were then applied to the study of micro-samples collected from mid-nineteenth century Northern Athapaskan porcupine quill work. Unexpectedly, the use of UPLC analysis and RBS-PIXE analysis allowed the characterisation of traded European natural dyes used with metallic mordants (copper and tin) on these samples, highlighting how European contact impacted on traditional Athapaskan porcupine quill work in the late nineteenth century (Chapter 5).

Dans le contexte actuel du réchauffement climatique, l'une des principales sources d'incertitude pour l'élévation du niveau de la mer est la contribution de la calotte Antarctique. L'étendue et les conditions météorologiques extrêmes de ce continent font de la télédétection spatiale un moyen utile pour son suivi sur le long terme. Les observations satellites altimétriques et radiométriques dans la gamme des micro-ondes rendent compte de l'évolution des propriétés du manteau neigeux de la calotte. L'altimétrie radar, par des mesures répétées de l'élévation de la topographie de surface, permet de quantifier les variations de volume sur l'ensemble du continent. Cependant, la pénétration de l'onde radar dans la neige affecte négativement cette quantification. Les méthodes proposées pour minimiser les erreurs de pénétration sont toutes basées sur des relations avec le coefficient de rétrodiffusion radar. La compréhension des variations annuelles et inter-annuelles du coefficient de rétrodiffusion est nécessaire pour améliorer la précision de l'estimation de l'élévation de la surface donc du bilan de volume de la calotte. Cette thèse a pour objectif d'étudier le coefficient de rétrodiffusion mesuré par les altimètres sur l'ensemble du continent, sujet qui jusqu'à aujourd'hui a reçu peu d'attention. Les altimètres radars embarqués à bord d'ENVISAT (bandes S et Ku) et de SARAL/AltiKa (bande Ka) ont des sensibilités différentes aux propriétés de la neige. Nous nous sommes intéressés aux caractéristiques annuelles et inter-annuelles des coefficients de rétrodiffusion dans ces trois bandes. Une étude de sensibilité a été réalisée avec un modèle électromagnétique afin de déterminer les propriétés du manteau neigeux qui dominent le signal saisonnier. On montre que le signal saisonnier est sensible à la densité et la rugosité de surface dans la bande S, à la température de la neige dans la bande Ka et à l'une ou à l'autre de ces variables selon la région dans la bande Ku. Les caractéristiques saisonnières du coefficient de rétrodiffusion sont ensuite comparées à celles des températures de brillance acquises par les radiomètres à bord de SARAL et de SSM/I. Les résultats indiquent une influence significative de la rugosité de surface sur les températures de brillance de la bande Ka, influence souvent considérée négligeable dans la modélisation de la température de brillance. Cette étude apporte une meilleure connaissance de la dynamique saisonnière des propriétés de proche surface de la calotte Antarctique. Elle fournit de nouveaux indices pour développer dans le futur des algorithmes robustes de correction de l'erreur de pénétration. Elle met également en lumière l'importance des missions altimétriques multi-fréquences et les possibilités qu'offrent le signal de la bande S pour l'étude des variabilités saisonnières de la rugosité de surface. En définitive, la rugosité de surface est un paramètre important à prendre en compte pour obtenir de meilleures estimations et modélisations des coefficients de rétrodiffusion et des températures de brillance. / In the context of global climate changes, the Antarctic ice sheet contribution to sea-level rise is one of the main uncertainty sources. The extent and extreme meteorological conditions of this continent render remote sensing a useful tool for long term monitoring. Altimetry and radiometry observations in the microwave range reveal variations of the volume of the ice sheet and surface properties of the snowpack. Radar altimeters, provide repeated observations of the surface topography elevation, which allow the quantification of volume variations of the ice sheet. However, the penetration of radar waves in dry and cold snowpack adversely affects the estimated surface elevation. Approaches to minimize the penetration error are all based on a relationship with the backscattering coefficient. Understanding the annual and interannual variations of the backscattering coefficient is thus a key issue in order to improve the estimation accuracy of the surface elevation and to refine the ice-sheet volume trend. This thesis aims at studying the backscattering coefficients acquired by radar altimeters, which until now have received little attention. Radar altimeters on board ENVISAT (S and Ku bands) and SARAL/AltiKa (Ka band) have different sensitivities to the snowpack properties. The annual and interannual variations of the backscattering coefficient at the three bands is investigated. Sensitivity tests are carried out with an electromagnetic model to determine the prevailing snowpack properties that drive the signal. The seasonal signal is sensitive to surface density and roughness at S band, to snow temperature at Ka band and to either snow surface density and roughness or temperature depending on the location on the continent at Ku band. The seasonal signal of the backscattering coefficient is then compared with that of the brightness temperature measured by radiometers on SARAL and SSM/I. The results show a significant influence of surface roughness on brightness temperatures at Ka band, which has often been neglected in brightness temperature modeling studies. This thesis provides a better understanding of the seasonal dynamics of the near surface properties of the Antarctic ice sheet. It also provides new clues to build a more robust corrections of the penetration errors in the future. It highlights the importance of multi-frequency altimetry missions and the potential of the S band to study the seasonal variability in surface roughness. In summary, surface roughness is an important property which should be taken into account for a better modeling of backscattering coefficient and brightness temperature.

La télédétection spatiale est d’une importance primordiale pour la cartographie et la surveillance des problèmes environnementaux. Son intérêt réside dans la capacité des capteurs satellitaires spatiaux à fournir des informations globales et permanentes de la planète, aux échelles locale à globale. La télédétection radar a montré son grand potentiel ces dernières années dans la caractérisation des états de surface du sol. L’état de la surface du sol, et en particulier l’humidité et la rugosité, exerce une influence fondamentale sur la répartition de la pluie entre infiltration, rétention superficielle et ruissellement. Il a un rôle essentiel dans les processus hydrologiques de surface et ceux associés à l’érosion et aux processus d’évapotranspiration. La caractérisation et la prise en compte de ces conditions de surface constituent actuellement un enjeu important pour la modélisation à base physique des processus hydrologiques ou pour le couplage surface-atmosphère. Dans ce cadre et depuis plusieurs années, plusieurs études scientifiques ont montré le potentiel des données micro-ondes actives dans l’estimation de l’état hydrique du sol et de sa rugosité de surface.Les nouveaux systèmes radar (SAR ʺSynthetic Aperture Radarʺ) ont permis d’ouvrir de nouvelles perspectives pour l’observation de la terre grâce à l’amélioration de la résolution spatiale (métrique sur TerraSAR-X et COSMO-SkyMed) et temporelle (TerraSAR-X, COSMO-SkyMed, Sentinel-1). La disponibilité depuis peu des nouveaux capteurs radar bande C Sentinel-1 (Sentinel-1A et Sentinel-1B) rend indispensable l’évaluation des données Sentinel-1 pour la caractérisation des états de surface du sol et en particulier la rugosité de surface.Le travail de thèse se structure en trois parties. La première partie consiste à évaluer les modèles de rétrodiffusion de radar les plus utilisés (IEM, Oh, Dubois and AIEM) en utilisant un large ensemble de données de SAR et des mesures expérimentales des paramètres du sol. Cette évaluation permet de trouver le modèle de rétrodiffusion le plus robuste qui simule le mieux le signal radar afin de l'utiliser par la suite dans la procédure d'inversion du signal radar pour estimer la rugosité du sol. Le deuxième axe de recherche de cette thèse consiste à proposer un modèle de rétrodiffusion radar semi-empirique pour les polarisations HH, HV et VV. Ce nouveau modèle sera construit à l'aide d'une grande base de données réelle. Ce nouveau modèle sera également utilisé dans la procédure d'inversion du signal radar pour estimer la rugosité du sol. Le dernier axe de cette thèse consiste à construire une méthode d’inversion du signal radar en utilisant les réseaux de neurones afin d’évaluer le potentiel des données Sentinel-1 pour l’estimation de la rugosité des sols en milieux agricoles. Ces réseaux de neurones seront entrainés à l'aide d'un ensemble de données synthétiques élaborées à partir des modèles de rétrodiffusion radar choisis (IEM calibré par Baghdadi et du nouveau modèle proposé) et validés en utilisant deux ensembles de données: un ensemble de données synthétiques et une base de données réelle (images Sentinel-1 et mesures in situ d’humidité et de rugosité du sol). La base de données réelle a été collectée en Tunisie (Kairouan) et en France (Versailles). / Spatial remote sensing is of paramount importance for mapping and monitoring environmental problems. Its interest lies in the ability of space satellite sensors in providing permanent information of the planet, at local, regional and global scales. Also, it provides spatial and repetitive territories visions and ecosystem views. Radar remote sensing has shown great potential in recent years for the characterization of soil surface conditions. The state of the soil surface, in particular moisture and roughness, has a fundamental influence on the distribution of rainfall between infiltration, surface retention and runoff. In addition, it plays an essential role in surface hydrological processes and those associated with erosion and evapotranspiration processes. Characterization and consideration of these surface conditions have been recently considered as an important issue for physically based modeling of hydrological processes or for surface-atmosphere coupling. In this context and for several years, several scientific studies have shown the potential of active microwave data for estimation of the soil moisture and the surface roughness.New SAR (Synthetic Aperture Radar) systems have opened new perspectives for earth observation through improved spatial resolution (metric on TerraSAR-X and COSMO-SkyMed) and temporal resolution (TerraSAR-X, COSMO-SkyMed, Sentinel-1) . The recent availability of new Sentinel-1 C-band radar sensors (free and open access) makes it essential to evaluate the potential of Sentinel-1 data for the characterization of soil surface conditions and in particular surface roughness.The work revolves around three parts. The first part consist of evaluation of the most used radar backscattering models (IEM, Oh, Dubois, and AIEM) using a wide dataset of SAR data and experimental soil measurements. This evaluation gives the ability to find the most robust backscattering model that simulates the radar signal with good agreement in order to use later in the inversion procedure of the radar signal for estimating the soil roughness. The second research axe of this thesis consists of proposing an empirical radar backscattering model for HH, HV and VV polarizations. This new model will be developed using a large real dataset. This new model also will be used in the inversion procedure of the radar signal for estimating the soil roughness. The last axe of this thesis consists of producing a method to invert the radar signal using neural networks. The objective is to evaluate the potential of Sentinel-1 data for estimating surface roughness. These neural networks will be trained using wide synthetic dataset produced from the radar backscattering models chosen (IEM calibrated by Baghdadi and the new proposed model) and validated using two datasets: one synthetic dataset and one real (Sentinel 1 images and in-situ measurements). The real datasets are collected from Tunisia (Kairouan) and France (Versailles).

The scope of this thesis is the study of the interplay between structure and magnetism in amorphous materials. The investigations focus on the growth of amorphous layers and the study of the influence of structural disorder and reduced physical extension on the magnetic properties of thin films and multilayers. The examined magnetic materials are FeZr alloys, as well as other amorphous transition metal alloys such as CoZr and FeCoZr. Thin films and multilayers of the studied materials were deposited using magnetron sputtering in ultra-high vacuum conditions. Their amorphous structure and layering quality was investigated using X-ray scattering techniques and in several cases with transmission electron microscopy. The chemical composition of the alloys was determined with Rutherford Backscattering Spectrometry. The magnetic properties were investigated using the magneto-optic Kerr effect and SQUID magnetometry, as well as polarized neutron reflectometry and X-ray magnetic circular dicroism measurements. For FeZr alloys deposited as multilayers with Al2O3 as spacer layer, it was found that Fe-rich nanocrystallites, formed at the metal/oxide interfaces, exert large influence on the magnetic properties. The use of AlZr alloys as buffer layers promotes the growth of highly amorphous FeZr layers. FeZr/AlZr multilayers with good layering quality can also be obtained. The influence of the reduced layer thickness on the magnetic moment, Curie temperature and magnetic dimensionality of the magnetic layers is addressed for FeZr/AlZr multilayers. Thin FeZr layers in these structures are found to belong to the 2D XY dimensionality class. The change of the magnetic moment and Curie temperature with reduced FeZr layer thickness is quantified. In addition, the induced magnetic moment in the alloy element Zr was investigated in FeZr and CoZr alloy films. The possibility to imprint a preferred magnetization direction during thin film preparation was demonstrated for FeCoZr layers. Lastly, AlZr alloy films were studied with respect to their oxidation stability at room and elevated temperatures, aiming towards development of materials with passivating properties.

Properties of magnetic thin film devices cannot be understood without detailed knowledge of their structure. For this purpose, a variety of thin film and multilayer systems have been studied. Both reciprocal space (low energy electron diffraction, reflection high energy electron diffraction, X-ray diffraction and reflectometry) and direct space (transmission electron microscopy) as well as Rutherford backscattering spectrometry have been applied. To gain understanding of an oxidation procedure for the growth of magnetite layers, thermal stability of iron layers on molybdenum seed layers has been investigated. Following the mosaicity and the out-of-plane coherence length over different ratios between the constituting layers allowed a deeper understanding of the limits of metallic superlattices. This, together with an approach to use hydrogen in the process gas during magnetron sputter epitaxy, opens routes for the growth of metallic superlattices of superior quality. A non-isostructural multilayer/superlattice system, Fe/MgO, has been investigated. In turn, this gave more understanding how superlattice diffraction patterns are suppressed by strain fields. As an alternative route to single-crystalline superlattices, amorphous multilayers present interesting opportunities. In this context, crystallization effects of iron/zirconium layers on alumiunium oxide were studied. Understanding these effects enables significant improvement in the quality of amorphous multilayers, and allows avoiding these, growing truly amorphous layers. Both the substantial improvement in quality of metallic superlattices, approaching true single-crystallinity, as well as the improvements in the growth of amorphous multilayers give rise to opportunities in the field of magnetic coupling and superconducting spin valves.

Nous avons montré que l'irradiation aux ions d'argon d'énergie comprise entre 1 et 15 MeV cause des dommages en surface du titane et du zirconium, qui prennent la forme d'une oxydation accélérée et/ou d'une cratérisation dont les effets évoluent en fonction de l'énergie du projectile et de l'atmosphère de recuit (température et pression), simulant les conditions environnementales représentatives de l'interface gaine/combustible d'un réacteur REP. Par AFM, nous avons montré que la surface du titane et du zirconium était attaquée par bombardement aux ions d'argon, à haute température (jusqu'à 500°C) en milieu faiblement oxydant (sous pression d'air sec raréfié comprise entre 5,7 10-5 Pa et 5 10-3 Pa) et à une dose moyenne fixée à environ 5 1014 ions.cm-2. On observe ainsi la formation de cratères nanométriques sur toute la surface du titane irradié entre 2 et 9 MeV et celle du zirconium irradié à 4 MeV, dont les caractéristiques varient en fonction de la température et de la pression. Dans le cas du couple Ar/Ti, l'efficacité d'endommagement superficiel augmente lorsque l'énergie du projectile diminue de 9 à 2 MeV. Par ailleurs, alors que la surface du titane apparaît transparente au faisceau d'ions à 15 MeV, celle du zirconium révèle de nombreux cratères micrométriques entourés d'un large halo sombre. Les caractéristiques des cratères (taille et densité superficielle) diffèrent de façon significative de celles observées à la fois dans le domaine des basses énergies (keV) où le dépôt d'énergie est contrôlé par les collisions balistiques (Sn) et dans le domaine des hautes énergies (MeV - GeV) où le dépôt d'énergie est contrôlé par les excitations électroniques (Se), ce qui n'était pas complètement inattendu dans le domaine d'énergie intermédiaire étudié, dans lequel des effets de pouvoir d'arrêt combiné Sn - Se sont envisageables. Par XPS couplé au décapage ionique, nous avons montré qu'il existe un effet d'irradiation sur l'oxydation thermique du titane, exacerbée sous faisceau d'ions d'argon entre 2 et 9 MeV, et qu'il existe aussi un effet d'énergie sur l'épaisseur et la stœchiométrie de l'oxyde. L'étude menée par Ellipsométrie Spectroscopique sur les films d'oxyde formés entre 1 et 9 MeV a corroboré ces résultats et montré précisément qu'il existe un pic d'oxydation en fonction de l'énergie d'ions d'argon, qui présente un maximum à 3 MeV, dans les conditions de l'expérience. Les mesures de gain d'oxygène effectuées par NBS confirment l'existence de ce pic d'oxydation. Les résultats acquis à ce jour par NBS concernant l'oxydation thermique du zirconium sous irradiation à l'argon de 4 et 9 MeV confirment les travaux antérieurs du groupe Aval du Cycle Electronucléaire de l'Institut de Physique Nucléaire de Lyon, et suggèrent fortement l'existence d'un pic d'oxydation dans la même plage d'énergie de projectile que pour le titane.

The primary challenge in wireless sensor network (WSN) deployment is the limited network lifetime due to the finite-capacity batteries. In accordance with this challenge, the vast majority of research efforts thus far have focused on the development of energy-efficient communication and computing mechanisms for WSNs. In this thesis, a fundamentally different approach and hence completely new WSN paradigm, i.e., the Passive Wireless Sensor Network (PWSN), is introduced. The objective of PWSN is to eliminate the limitation on the system lifetime of the WSNs. In PWSN, power is externally supplied to the sensor network node via an external RF source. Hence, the lifetime of the system is no longer determined by the lifetime of the batteries. An alternative communication scheme, modulated backscattering, is also discussed to be utilized in PWSN. The feasibility of the proposed system is investigated along with the open research challenges for reliable communication and networking in PWSN. Additionally, a new medium access schemee for PWSN, Ultra-Wideband PWSN Medium Access Control (UWB PWSN MAC), is presented.