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In the LUXCAT project of the ESA (European Space Agency), backscatter data was acquired from a corn field in Luxembourg in 2022. This project focuses on validating and analysing these data, creating different tools to extract measurements from the raw data. It is also expected that these tools can be used to continue the analysis of future campaigns. The conclusion of this project is the need for calibration of the backscatter data from external calibrators or external calibration. The project has been carried out to provide value to the members of the LUXCAT project and to assist in the development of geostationary SAR systems from the resources created., En el proyecto LUXCAT de la ESA (European Space Agency), se adquirieron datos de retrodispersión de un campo de maíz en Luxemburgo en 2022. Este proyecto se centra en validar y analizar estos datos, creando diferentes herramientas que permitan extraer medidas a partir de los datos en crudo. Se espera, también, que estas herramientas puedan ser usadas para continuar el análisis de futuras campañas. La conclusión de este proyecto es la necesidad de calibrar los datos de retrodispersión a partir de calibradores externos o calibración externa. El proyecto se ha llevado a cabo con el fin de aportar valor a los miembros del proyecto LUXCAT y de ayudar en el desarrollo de sistemas SAR geoestacionarios a partir de los recursos creados., Al projecte LUXCAT de la ESA (European Space Agency), es van adquirir dades de retrodispersió d'un camp de blat de moro a Luxemburg en el 2022. Aquest projecte es centra en validar i analitzar aquestes dades, creant diferents eines que permetin extreure mesures a partir de les dades en cru. També s'espera que aquestes eines puguin ser utilitzades per continuar l'anàlisi de futures campanyes. La conclusió d'aquest projecte és la necessitat del calibratge de les dades de retrodispersió a partir de calibradors externs o calibratge extern. El projecte s'ha dut a terme per aportar valor als membres del projecte LUXCAT i ajudar en el desenvolupament de sistemes SAR geoestacionaris a partir dels recursos creats.

Albeit recent technological developments (e.g. field deployable instruments operating at high temporal frequencies), experimental hydrology is a discipline that remains measurement limited. From this perspective, trans-disciplinary approaches may create valuable opportunities to enlarge the number of tools available for investigating hydrological processes. Tracing experiments are usually performed in order to investigate the water flow pathways and water sources in underground areas. Since the 19th century, researchers have worked with hydrological tracers to do this. Among them, the fluorescent dyes and the isotopes are the most commonly used to follow the water flow while others like salts or bacteriophages are employed as additional tracers to those mentioned above. Bacteriophages are the least known of all, but it has been studied since the 1960s as hydrological tracers, especially in karstic environments. The purpose is to evaluate the potential for bacteriophages naturally occurring in soils to serve as a new environmental tracer of hydrological processes. We hypothesize that such viral particles can be a promising tool in water tracing experiments since they are safe for ecosystems. In both fields of hydrology and virology, the knowledge regarding the fate of bacteriophages within the pedosphere is still limited. Their study would not only allow proposing potential new candidates to enlarge the hydrological tracers available, but also improving the current knowledge about the bacteriophage communities in soil and their interactions with certain environmental factors. For this purpose, we aim at describing the bacteriophage communities occurring in the soil through shotgun metagenomics analysis. Those viruses are widely spread in the pedosphere, and we assume that they have specific signatures according to the type of soil. Then, bacteriophage populations will be investigated in the soil water to analyse the dis/similarities between the two communities as wel

This work examines the practice of reading aloud in the interactional context of adult participants engaging in an interface-mediated collaborative game activity. With a conversation analytic approach onto video data of user studies, empirical cases of reading aloud are presented. It is shown how participants multimodally co-organise reading aloud in-interaction for providing accessibility to game text in a game that is unfamiliar to them. With reading aloud, participants meet the interactional challenge of making game text audibly accessible that is not always visually accessible for all participant alike. This practice is not only conducted for another but with another in a truly joint fashion, working as a continuer to accomplish the unfamiliar game.

The general scope of the PhD research project falls within the framework of developing integrated catchment hydro-biogeochemical theories in the context of the Critical Zone (CZ). Significant advances in the understanding of water transit time theory, subsurface structure controls, and the quantification of catchment scale weathering rates have resulted in the convergence of classical biogeochemical and hydrological theories. This will potentially pave the way for a more mechanistic understanding of CZ because many challenges still exist. Perhaps the most difficult of all is a unifying hydro-biogeochemical theory that can compare catchments across gradients of climate, geology, and vegetation. Understanding the processes driving the evolution of chemical tracers as they move through space and time is of cardinal importance to validating mixing hypotheses and assisting in determining the residence time of water in CZ. The specific aim of the study is to investigate what physical and biogeochemical processes are driving variations in observable endmembers in stream discharge as a function of the hydrological state at headwater catchment scale. This requires looking beyond what can be observed in the stream and what is called ”unseen flowlines” in this thesis. The Weierbach Experimental Catchment (WEC) in Luxembourg provides a unique opportunity to study these processes, with an extensive biweekly groundwater chemistry dataset spanning over ten years. Additionally, WEC has been the subject of numerous published works in the domain of CZ science, adding to an already detailed hydrological and geochemical understanding of the system. Multivariate analysis techniques were used to identify the unseen flowlines in the catchment. Together with the excising hydrological perception model and a geochemical modelling approach, these flowlines were rigorously investigated to understand what processes drive their respective manifestations in the system. The existing perceptual mod

Climate change due to the increase in GHG emissions and energy crisis due to scarcity of fossil fuel availability are an ever growing issue for the planet and countries. The decarbonization and the sustainability of the energy sector is one of the top priority to achieve a resilient system. Hydrogen has been considered for decades to be used as an alternative for fossil fuel and now is the time of development for an hydrogen based economy. Fuel cells are devices that convert the hydrogen chemical energy into electrical energy and is one the main component considered for the hydrogen economy. However, much is yet to be achieved to make their manufacturing as cheap and as efficient as possible. Chemical vapour deposition (CVD) is a technique used to synthesize solid materials from gaseous precursors which has the advantages, over wet chemistry, to reduce wastes of production, to be cheap, to make pure solid materials and to be easily scalable. In this thesis we investigated the possibility to use CVD to produce two major components of fuel cells, namely the gas diffusion layer and the proton exchange membrane. The results were highly promising regarding the elaboration of gas diffusion layers and a CVD prototype was assembled to make the highly complex copolymerization of proton exchange membrane a reality with promising initial results.

For decades, antimicrobial resistance has been considered as a global long-lasting challenge. If no action is taken, antimicrobial resistance-related diseases could give a rise up to 10 million deaths each year by 2050 and 24 million people might end into extreme poverty. The ever-increasing spread and cross-transmission of drug-resistant foodborne pathogens such as Campylobacter spp. between reservoirs, such as human, animal and environment are of concern. Indeed, because of the over-exposition and overuse of antibiotics in food-producing animals, the latter could carry multidrug resistant Campylobacter that could be transmitted to humans via food sources or from direct animal contacts. One of the solutions to tackle antimicrobial resistances is the development of rapid diagnostics tests to swiftly detect resistances in routine laboratories. By detecting earlier AMR, adapted antibiotherapy might be administrated promptly shifting from empirical to evidence-based practices, conserving effectiveness of antimicrobials. The already implemented cost- and time-efficient MALDI-TOF MS in routine laboratories for the identification of microorganisms based on expressed protein profiles was successfully applied for bacterial typing and detection of specific AMR peak in a research context. In the line of developing rapid tests for diagnostics, MALDI-TOF MS appeared to be an ideal candidate for a powerful and promising “One fits-all” diagnostics tool. Therefore, the present study aimed to get more insights on the ability of MALDI-TOF MS-protein based signal to reflect the AMR and genetic diversity of Campylobacter spp. The groundwork of this research consisted into the phenotypic and genotypic characterization of a One-Health Campylobacter collection. Then, isolates were submitted to protein extraction for MALDI-TOF MS analysis. Firstly, mass spectra were investigated to screen AMR to different classes of antibiotics and to retrieve putative biomarkers related to already known

The thesis is focused on developing spectral selective coatings (SSC) composed of multilayer cermets and periodic array of resonating omega structures, turning them to behave like metamaterials, while showing high thermal stability up to1000°C. The developed SSC is intended to be used for the concentrated solar power (CSP) applications. With the aim of achieving highest possible absorbance in the visible region of the spectrum and highest reflectance in the infrared region of the spectrum. The thesis highlights the numerical design, the synthesis and optical characterization of the SSC of approximately 500 nm thickness. A bottom-up approach was adopted for the preparation of a stack with alternate layers, consisting of a distribution of Titanium Nitride (TiN) nanoparticles with a layer of Aluminum Nitride (AlN) on top. The TiN nanoparticles, laid on a Silicon substrate by wet chemical method, are coated with conforming layer of AlN, via Plasma-enhanced Atomic Layer Deposition (PE-ALD). The control of the morphology at the nanoscale is fundamental for tuning the optical behaviour of the material. For this reason, two composites were prepared. One starting with TiN dispersion made with dry TiN powder and deionized water, and the other with ready-made TiN dispersion. Nano-structured metamaterial based absorbers have many benefits over conventional absorbers, such as miniaturisation, adaptability and frequency tuning. Dealing with the current challenges of producing the new metamaterial based absorber with optimal nanostructure design along with its synthesis within current nano-technological limits, we were capable of turning the cermets into metamaterial. A periodic array of metallic omega structures was patterned on top of both the composites I and II, by using e-beam lithography technique. Parameters, such as the size of TiN nanoparticles, the thickness of AlN thin film and the dimensions of the omega structure were all revealed by the numerical simulations, perform

For gas sensing applications, metal oxide (MOx) nanostructures have demonstrated attractive properties due their large surface-over-volume ratio, combined with the possibility to use multiple materials and multi-functional properties. For MOx chemiresistive gas sensors, the temperature activated interaction of atmospheric oxygen with MOx surface plays a major role in the sensor kinetics as it leads to oxygen adsorption-desorption reactions, that eventually affects the gas sensing performance. Thus, MOx sensors are operated at high temperatures to achieve the desired sensitivity. This high temperature operation of MOx sensors limits their application in explosive gas detection, reduces the sensor lifetime and causes power consumption. To overcome these drawbacks of MOx sensors, researchers have proposed the use of heterostructures and light activation as alternatives. In this thesis, we aim to develop low power consuming MOx sensors using these solutions. We show the template-free bottom-up synthesis and shape control of copper hydroxide-based nanostructures grown in liquid phase which act as templates for formation of CuO nanostructures. Precise control over the pH of the solution and the reaction temperature led to intended tuning of the morphology and chemical composition of the nanostructures. We contemplate upon the rationale behind this change in shape and material as CuO nanostructures are further used in a heterostructure. We discuss synthesis and characterisation of CuO bundles and Cu2O truncated cubes, former of which lead to very interesting gas sensing properties and application. Devices made from CuO bundles network are investigated for their electrical and oxygen adsorption- desorption properties as a gas sensor. It was observed that the sensor has faster response and recovery in as deposited condition in comparison to annealed sensor. A detailed inspection of response and recovery curves enabled us to derive parameters like time constants, reaction con

Caloric materials are suggested as energy-efficient refrigerants for future cooling devices. They could replace the greenhouse gases used for decades in our air conditioners, fridges, and heat pumps. Among the four types of caloric materials (electro, baro, elasto, magneto caloric), electrocaloric materials are more promising as applying large electric fields is much simpler and cheaper than the other fields. The research in the last years has been focused on looking for electrocaloric materials with high thermal responses. However, the energy efficiency crucial for future replacement of the vapor compression technology has been overlooked. The intrinsic efficiency of electrocaloric has been barely studied. In the present dissertation, we will study the efficiency of EC materials defined as materials efficiency. It is the ratio of the reversible electrocaloric heat to the reversible electrical work required to drive this heat. In this work, we will study the materials efficiency of the benchmark lead scandium tantalate in different shapes (bulk ceramic and multilayer capacitors). A comparison to other caloric materials is presented in this dissertation. Our work gives more insights on the figure merit of materials efficiency to further improve the efficiency of our devices.

Ferroelectric materials are ubiquitous in several applications and offer advantages for microelectromechanical systems (MEMS) in their thin film form. However, novel applications require ferroelectric films to be deposited on various substrates, which requires effective integration and know-how of the material response when selecting a substrate for film deposition. As substrate-induced stress can alter the ferroelectric properties of the films, the knowledge of how stress changes the ferroelectric response under different actuation conditions is essential. Furthermore, the stress-dependent behavior raises the question of understanding the reliability and degradation mechanisms under cyclic electric loading. Therefore, the ferroelectric thin film’s fatigue and breakdown characteristics become more relevant. Lead zirconate titanate (PZT) thin films are popular among other ferroelectric materials. However, there is a tremendous effort made in the direction of finding a lead-free alternative to PZT. Ferroelectric thin films can be deposited using different processing techniques. In this work, the chemical solution deposition route is adapted for depositing PZT thin films on transparent and non-transparent substrates. A correlation between the substrate-induced ferroelectric properties and processing conditions with different electrode configurations is established. Finite element modeling is used to understand the influence of the design parameters of the co-planar interdigitated electrodes for fabricating fully transparent PZT stacks. In-plane and out-of-plane ferroelectric properties of PZT thin films in metal-insulator-metal (MIM) and interdigitated electrode (IDE) geometries, respectively, on different substrates, are compared to establish the connection between the stress-induced effect and the actuation mode. It is shown that the out-of-plane polarization is high under in-plane compressive stress but reduced by nearly four times by in-plane tensile stress. In con

Controlling biomolecule-surface interactions with nano- and micro-engineered surfaces is of great interest in biomedical applications such as tissue regeneration and biosensing platforms. Developing high-performance functional bio-interfaces for cell-surface or protein-surface interactions necessitates optimizing the interface by modifying material surface variables. Surface gradients are a category of combinatorial technique that enables monitoring and high-throughput optimization of biomolecule-surface interactions by providing a gradually varying surface parameter(s) on a small scale and across an extended area length. It is elaborated that a surface gradient not only greatly reduces the required time and labour of conducting numerous separate experiments for producing several distinct samples but also minimises the inter-batch errors associated with. In this context, multigradients are particularly promising for advanced bio-interface optimisation since they incorporate two or more separate gradients that evolve independently across different directions. While gradients have been vastly studied in past two decades, reporting different surface gradients of chemistry, topography, or mechanical nature in either nano or larger scales, there have been few studies on multigradients, due to the limited operational flexibility required for generating more than one gradient on the surface. First, plasma technologies were explored for establishing a suitable fabricating method for generating spatial variation of surface chemistry along a direction. Both the mask-assisted static and maskless dynamic deposition were examined via two different plasma technologies, namely atmospheric pressure plasma and low-pressure plasma. Depending on the electrical conductivity of the chosen substrates and the nature of the coatings, different surface characterisations were performed on the generated samples. Surface chemistry, surface morphology and wettability properties of the treated s

The most characteristic functional property of antiferroelectric materials is the possibility to induce a phase transition from a nonpolar to a polar phase by an electric field. Here, we investigate the effect of this field-induced phase transition on the birefringence change of PbZr0.95Ti0.05O3. We use a transparent polycrystalline PbZr0.95Ti0.05O3 film grown on PbTiO3/HfO2/SiO2 with interdigitated electrodes to directly investigate changes in birefringence in a simple transmission geometry. In spite of the polycrystalline nature of the film and its moderate thickness, the field-induced transition produces a sizable effect observable under a polarized microscope. The film in its polar phase is found to behave like a homogeneous birefringent medium. The time evolution of this field-induced birefringence provides information about irreversibilities in the antiferroelectric switching process and its slow dynamics. The change in birefringence has two main contributions: One that responds briskly and a slower one that rises and saturates over a period of as long as 30 min. Possible origins for this long saturation and relaxation times are discussed.

Advances in networking and hardware technology have made the design and deployment of Internet of Things (IoTs) and decentralised applications a trend. For example, the fog computing concept and its associated edge computing technologies are pushing computations to the edge so that data aggregation can be avoided to some extent. This naturally brings benefits such as efficiency and privacy, but on the other hand, it forces data analysis tasks to be carried out in a distributed manner. Hence, we will focus on establishing a secure channel between an edge device and a server and performing data analysis with privacy protection. In this thesis, we first studied the state-of-art Key Exchange (KE) and Authenticated Key Exchange (AKE) protocols in the literature, including security properties, security models for various security properties, existing KE and AKE schemes of pre-quantum and post-quantum era with varied authentication factors. As a result of the above research, a novel IoT-oriented security model for AKE protocol is introduced. In addition to the general security properties satisfaction, we also define several detailed security games for the desired security properties of perfect forward secrecy, key compromise impersonation resilience and server compromise impersonation resilience. Furthermore, by studying the current multi-factor AKE protocols in the literature, we are inspired by the usage of bigdata in the IoT setting for the authentication and session key establishment propose. With this in mind, we proposed a bigdata-facilitated two-party AKE protocol for IoT systems that uses the bigdata as one of the authentication factors. Moreover, we also proposed a modular framework for constructing IoT-server AKE in post-quantum setting. It is flexible that it can integrate with a public key encryption and a KE component. In addition to this, we notice that as IoT generates and collects more and more data, the need to perform data analysis increases at the same t

The progressive trend to miniaturize samples presents a challenge to materials characterization techniques in terms of both lateral resolution and chemical sensitivity. The latest generation of focused ion beam (FIB) platforms has allowed to advance in a variety of different fields, including nanotechnology, geology, soil, and life sciences. State-of-the-art ultra-high resolution electron microscopy (EM) devices coupled with secondary ion mass spectrometry (SIMS) systems have enabled to perform in-situ morphological and chemical imaging of micro- and even nanosized objects to better understand materials by studying their properties correlatively. However, SIMS images are prone to artefacts induced by the sample topography as the sputtering yield changes with respect to the primary ion beam incidence angle. Knowing the exact sample topography is crucial to understand SIMS images. Moreover, using non-reactive primary ions (Ne+) produced in a gas field ion source (GFIS) allows to image in SIMS with an excellent lateral resolution of < 20 nm, but it comes with a lower ionization probability compared to reactive sources (e.g., Cs+) and due to small probe sizes only a limited number of atoms are sputtered, resulting in low signal statistics. This thesis focused first on taking advantage of high-resolution in-situ EM-SIMS platforms for applications in specific research fields and to go beyond traditional correlative 2D imaging workflows by developing adapted methodologies for 3D surface reconstruction correlated with SIMS (3D + 1). Applying this method to soil microaggregates and sediments allowed not only to enhance their visualization but also to acquire a deeper understanding of materials’ intrinsic transformation processes, in particular the organic carbon sequestration in soil biogeochemistry. To gain knowledge of the influence of the topography on surface sputtering, using model samples the change of the sputtering yield under light ion bombardment (He+, Ne+) for dif

Global energy demand propelled humankind in search of clean and renewable energy sources. Among them, solar energy outstands all the available renewable sources. In this context, concentrated solar thermal technology (CST) and hydrogen storage via solar water splitting significant feature contributions in global power generation. Nevertheless, the major challenge in CST technology is achieving a high solar absorption selectivity with thermal stability above 923 K. Whereas the limited chemical stability and low performance remain significant challenges in solar water-splitting technology. We address these technologies' critical issues through multiwalled carbon nanotubes (MWCNT)-metal oxide hybrid materials. MWCNTs are known for their high solar absorption, thermal and electrical conductivity. While metal oxides such as VO2, Al-doped ZnO are known for their infrared reflecting properties with high transparency in the visible region. TiO2 and ZnO have appropriate band positions for water splitting reactions. Here, combining CNTs and metal oxides at the nanoscale leads to unique properties not present in individual constituents. We fabricate the MWCNT-metal oxide through the hybrid chemical vapour deposition-atomic layer deposition (CVD-ALD) process. Here the CVD is implemented to grow MWCNTs, while ALD is used to produce conformal metal oxide shells on the 3D porous MWCNT structures. The MWCNT-VO2 nanostructures performed in this study feature a solar selectivity modulation across the semiconductor-metal transition temperature of VO2, i.e., 67˚C. The thermally induced optical modulation was investigated as a function of the morphology of VO2 phase. The grown VO2 nanoparticles on MWCNT illustrate an enhancement in the spectral emissivity across the SMT temperature. A contrasting optical modulation is displayed by the continuous VO2 layer on MWCNT. Aluminium doped zinc oxide (AZO) layer (4.7 at %) illustrated solar absorbance of 0.96 and thermal emittance of 0.6. The li

Attention allows pieces of information stored in visuospatial short-term memory (VSSTM) to be selectively processed. Previous studies showed that internal shifts of attention in VSSTM in response to a retro-cue are accompanied by eye movements in the direction of the position of the memorized item although there is nothing left to look at. This finding raises the possibility that internal shifts of attention in VSSTM are underpinned by mechanisms originally involved in the planning and control of eye movements. To explore this possibility, we investigated the ability of an individual with congenital horizontal gaze paralysis (HGP2) to shift her attention horizontally or vertically toward a memorized item within VSSTM using a retro-cue paradigm. As efficient oculomotor programming is not innate but requires some trial and error learning and adaptation to develop, congenital paralysis prevents this development. Consequently, if shifts of attention in VSSTM rely on the same mechanisms as those supporting the programming of eye movements, then horizontal congenital gaze paralysis should necessarily prevent typical retro-cueing effect in the paralyzed axis. At odds with this prediction, HGP2 showed a typical retro-cueing effect in her paralyzed axis. This original finding indicates that selecting an item within VSSTM is not made by saccade programming and that it does not depend on the ability to program it.

Ozone is a major concern for indoor office pollution. Recurring exposure to low levels of ozone (in ppb range) can be associated with several cardiopulmonary diseases. As such, there is a need for cheap, easy-to-integrate ozone gas sensors that can achieve good performance and work as an alarm for dangerous ozone concentrations. In this work, we propose the use of off-stoichiometric copper-chromium-oxide, that has shown great reversible measurements at low temperature for ozone detection, as low as 50 ppb. The selectivity compared with molecular oxygen is shown. Near-Atmospheric Pressure X-Ray Photoelectron Spectroscopy led to the understanding of the ozone - delafossite surface reaction. This work discloses pioneering results in the fabrication of low cost, high sensitivity ozone sensors based on a p-type material.

Polymeric cord-rubber composites play a vital role in the performance of a tire. They provide dimensional stability, strength to the sidewall, absorb shock, etc. in the tires. The polymer cords used in these composites are dipped in resorcinol–formaldehyde–latex (RFL) adhesive to improve the cord-rubber adhesion. Not enough studies have been performed to fully understand the RFL interfacial region and its structural changes in course of tire usage. Moreover, its detailed structure and its evolution during thermal exposure has not been fully resolved. This study has been dedicated in understanding the structural properties of the RFL interfacial layer and its evolution upon thermal treatment in cord-rubber composites. Firstly, pure RFL adhesive properties were investigated when subjected to accelerated thermal exposure. The DMA and AFM measurements highlighted an increase of the modulus of the latex phase and the resin phase during thermal treatment in the presence of curatives. However, no changes occurred in the latex phase in RFL without curatives samples during thermal treatment. Such results demonstrated that the increase of modulus of the latex phase during thermal treatment was mainly due to the presence of curatives through the co-vulcanization process highlighted by NMR. Then, a model composite system composing RFL dipped polyamide monofilaments embedded in a rubber matrix was developed. A multiscale methodology was implemented to study the RFL interfacial region when the model composite was subjected to thermal treatment. While the macroscopic interfacial adhesion properties decreased with thermal treatment, an increase in the local modulus in RF resin and latex phases of the interfacial region was observed by AFM. The SEM-EDX results indicated the presence of oxygen in the RFL region which was facilitating the resin hardening in the RF phase. The further crosslinking in the latex phase due to the presence of sulfur curatives resulted in the increase of the

The piezotronic effect relies on the creation of piezoelectric polarization charges mechanically induced within a piezoelectric semiconductor to modulate the carrier dynamics across electronic contact interfaces. The field of piezotronics is a relatively new area of study, based on a mechanical signal triggering, which is one of the most common kind of interactions between the environment and electronic systems. It started to draw a considerable attention in the early 2010’s, by reaching higher electromechanical sensitivities when compared to conventional methods of sensing. The rapidly spreading Internet-of-Things is accelerating Micro-ElectroMechanical Systems (MEMS) industry to deliver highly sensitive and miniaturized self-sensing sensors with low power consumption and cost-effective production process. Within this context, strain sensors based on the piezotronic effect appear as promising candidates to address these needs. However, several crucial questions remain unanswered or need to be refined, concerning the design and integration of piezotronic junctions with its fabrication process into microsystems or MEMS, the optimal configuration for strain sensing as well as noise studies for such systems. This PhD thesis proposes to rationalize the piezotronic effect for strain sensors and presents a novel microfabrication process integrating for the first time piezotronic strain sensors in millimetre-sized cantilevers on flexible polymeric substrates by means of maskless laser lithography. The atomic layer deposition (ALD) technique was used for the deposition of ZnO polycrystalline thin films on high work function metals to obtain Schottky junctions. However, such ZnO-based Schottky junctions by ALD have never been post-processed and integrated into a strain sensor. We propose to rationalize the ALD processing to obtain wurtzite polycrystalline zinc oxide thin films with a privileged (002) orientation and to make it compatible with microfabrication processing on p, L’effet piézotronique repose sur la création de charges de polarisation piézoélectriques d’origine mécanique induites au sein d’un semiconducteur piézoélectrique, afin de moduler la dynamique des porteurs de charges au travers d’interfaces de contact électroniques. Le domaine des dispositifs piézotroniques est un champ d’études relativement nouveau, basé sur un signal de déclenchement mécanique, représentant l’une des interactions les plus fréquentes entre l’environnement et les systèmes électroniques. Ce domaine d’études a commencé à attirer une attention considérable au début des années 2010, en atteignant des sensibilités électromécaniques supérieures en comparaison aux méthodes de détection conventionnelles. La propagation rapide de l’Internet-of-Things a accéléré l’industrie des Micro-ElectroMechanical Systems (MEMS) à délivrer des capteurs ultra-sensibles, miniaturisés, à détection intégrée, présentant une faible consommation énergétique ainsi qu’un procédé rentable de production. Dans ce contexte, les capteurs de déformation basés sur l’effet piézotronique apparaissent comme des candidats prometteurs afin de répondre à ces besoins. Cependant, de nombreuses questions cruciales demeurent sans réponse ou doivent être affinées, concernant le design et l’intégration de jonctions piézotroniques avec leurs procédés de fabrication au sein de microsystèmes ou de MEMS, la configuration optimale pour la détection de déformation ainsi que les études de bruit pour de tels systèmes. Ce projet de thèse propose de rationnaliser l’effet piézotronique appliqué aux capteurs de déformation et présente un nouveau procédé de microfabrication intégrant pour la première fois des capteurs de déformation piézotroniques dans des leviers millimétriques sur des substrats flexibles polymériques, au moyen de lithographie laser sans masque. Le procédé d’atomic layer deposition (ALD) a été utilisé pour la déposition de couches minces polycristallines de ZnO sur des métaux à haut travail de s

Plasma polymerization is an attractive and powerful tool for synthesizing functional polymeric thin films with highly cross-linked structures. So far, in plasma many non-negligible side reactions promote the synthesis of polymers with a structure different from those obtained by conventional polymerization processes. Namely, the network architecture could be a consequence of the functional group's sacrifice on behalf of the cross-link’s formation. Remarkably, conducted at atmospheric pressure plasma polymerization is evidenced to promote the conventional polymerization pathway assuring good retention of functional groups from monomers in a vapor or liquid phase. Yet, sacrificed to the benefit of the functional groups - the cross-links, lack further contribution to the mechanical and chemical stability, limiting the long-term application. In other words, the current state of the atmospheric pressure plasma polymerization requires a balance between available functional groups and cross-links. Consequently, as an effective method for an adequate reinforcement of cross-linked structure, maintaining a high concentration of the functional groups arises the combination of two polymeric networks in Interpenetrating Polymer Networks (IPN). However, the formation of IPN architecture in the plasma process has yet to be reported. In this context, this thesis aimed to examine the deposition of the thin films with the IPN architecture, utilizing an atmospheric pressure continuous sinusoidal plasma in the synthesis pathway. The primary objective was to evaluate the formation of the IPN system in-situ, in a sequential manner from telechelic oligomers. The convenience of the one-pot, in-situ, IPN formation involves foremost an immediate network's interlocking already during synthesis, thus providing forced compatibilization and reducing possible phase separation. To facilitate direct network formation, thin films were prepared from telechelic poly(ethylene glycol) (PEG) oligomers wi

Among the noble metals, silver (Ag) presents the lowest electrical resistivity at low thickness, the highest reflectance from visible to infrared spectra and the lowest thermal conductivity. Consequently, it is used in a large range of applications, either as nanoparticle (NP) films, e.g. in devices based on localized surface plasmon resonance, or as continuous thin films for highly reflective optical mirrors or as infrared reflecting coatings. Although copper (Cu) is widely used in the field of microelectronics, Ag is a good candidate as a potential replacement of Cu for interconnects in integrated circuits (ICs) thanks to its lower residual stress and the absence of considerable increase of resistivity when downscaling. Among the non-line-of-sight vacuum deposition method, atomic layer deposition (ALD) is known for its ability to produce an accurate and precise thickness control giving uniform and conformal film growth thanks to the sequential and self-limiting surface reactions of precursors. However, the ALD of silver is still weakly understood, and the uniform deposition over large scale is often not demonstrated. It is also very challenging to obtain an ultra-thin continuous Ag films due to the growth mechanism leading to islands films rather than continuous layer. One part of this thesis work is dedicated to take advantage of the nanoparticle morphology and overcome the challenge of the good control of the morphology of Ag nanostructures on large-scale surfaces by an understanding of the growth mechanism. The uniformity of the deposition of silver NPs by plasma-enhanced ALD (PE-ALD) is quantified in terms of film morphology as well as chemical composition and crystalline structure over an 8-inch surface area. After a careful investigation of the PE-ALD parameters and their impact on the Ag deposition, we prove the self-saturated regime required for obtaining good control of the deposition and large-scale uniformity. An empirical model which explains the silve

This thesis address the general problem of safe and secure transport of dangerous goods (TDG). The TDG is very complicated to manage because of risk for the environment and human life. Currently, it suffers from a lack of efficiency, trust, and t ransparency. In this thesis, we propose a novel method to specify the workflow aspects of TDG by considering all TDG process stages during its entire lifecycle. This method aims to facilitate the specifications of the TDG workflow management system that is entirely based on existing regulatory frameworks ensuring the compliance, trust, and transparency of all underlying processes. The proposed system design method is based on the so-called model-driven architecture (MDA) approach and enhancing it to consider blockchain properties. The first stage is the formal analysis of the process of TDG and its alignment with the regulatory frameworks. The proposed design method aims, at this stage, to allow the formal definition and verification of the design of the system with regard to the regulatory frameworks. The next stages of the method rely strongly on the model transformation that is a salient aspect of the proposed design method. Model transformation allows to automatically discover peer system components and authorized interactions. The last stage of the whole model transformations is the specification of digital twin profiles for all potential s t akeholders. All the interactions in the real world between stakeholders are transformed into interactions in the digital world, while the interactions with the environment are achieved through the use of IoT. The proposed approach enables interactions between components of the systems (digital twins, IoT devices, etc.) only if this is compliant with the regulatory framework. Thanks to blockchain technology, our design method allows improving trust and transparency in the process of TDG from the perspective of stakeholder collaborations. Smart contract technological capabilities ar

Plasma-assisted approaches are broadly used in thin-film deposition, surface preparation and top-down fabrication. Particularly, plasma processes, which can operate at atmospheric pressure, have ensured the simultaneous synthesis and deposition of numerous thin film compositions that have met multiple applications. Yet, the wide variety of reactive species composing plasmas induces a non-negligible amount of side reactions that result in a lack of regularity in polymeric materials compared to the ones formed by wet chemical polymerisation processes. The combination of ultrashort nanosecond plasma discharge (t_ON ≈ 100 ns) and long plasma OFF-time (t_OFF = 0.1 – 100 ms), for the initiation and propagation of the free-radical polymerisation reaction, was recently demonstrated to yield the formation of conventional polymer layers. Based on the current understanding of the process, i.e. significance of the plasma pulse frequency, this thesis aims at gaining a deeper insight in the influence of other important parameters. The nanosecond pulsed plasma deposition of low dielectric constant insulating thin films is studied. Providing additional dimensions to the characterisation, the dielectric layer’s properties such as the leakage current and the dielectric constant, allow to discriminate mechanisms that would not have been identified from other techniques. Hence, ensuring the further development of the fundamental understanding of the nanosecond pulsed plasma approach. From the nanosecond pulsed plasma deposition reaction of different tetra-organosiloxane compounds, the growth mechanisms driving the formation of insulating polymer layers are elucidated. For vinylic monomers, the plasma-induced polymerisation is demonstrated to be highly favour over plasma-state polymerisation at low plasma pulse frequency. This yields the excellent retention of the monomer structure and the prevalence of surface reactions, which are essential to obtain remarkable insulating properties. I

The mechanical performance of tires is controlled by many of the ingredients used in their production. Among them, novolac-type phenolic resins (PR) are petroleum-based materials commonly employed to reinforce rubber compounds. Even though overall performance is efficient, there is a growing societal need to develop alternatives to these resins as they are challenged by REACH regulations. Benzoxazine resins (Bz) are a new generation of materials that can be suitable for this purpose; they hold potential for improvement of both the mechanical properties and the sustainability of the rubber compounds. However, while PR have been extensively used and their interactions with tire compounds are well known, the use of benzoxazines in rubber compounds requires extensive studies and in-detail investigations. This thesis aims at filling this gap and designing benzoxazine resins that could be relevant alternatives to PR. For this purpose, novel sulfur containing dibenzoxazines were successfully synthesized and their interactions with rubber compounds were methodically investigated. Diphenolic compounds with either disulfide bonds (S‒S), or monosulfide bonds (‒S‒) were reacted with monoamines such as furfurylamine, a bio-based amine produced from agricultural byproducts. These partially bio-based original precursors, which were never reported before, exhibited polymerization behaviors that greatly fit the required conditions for rubber vulcanization. Indeed, the curing of these novel benzoxazine monomers occurred during rubber vulcanization, allowing the elaboration of reinforced materials at the molecular scale without detrimental side-reactions with the curing package. A fine investigation of the mechanical and thermal properties of the resulting rubber compounds indicated the reinforcing effect of these new resins at the macroscale. Therefore, the potential of each benzoxazine to act as a reinforcing resin was tested in real tire parts confirming the potential of Bz to be u

Antiferroelectrics are a subcategory of ferroic materials that display no spontaneous polarisation due to antiparallel ionic displacements. These materials undergo an electric field-induced transition to a polar phase accompanied by the emergence of a spontaneous polarisation. As for ferroelectrics, heating up an antiferroelectric material above a certain temperature Tc will cause another phase transition towards a paraelectric phase. Antiferroelectricity is currently the subject of a renewed interest, mostly due to a rising need of new smart materials for applications such as energy storage, electrocaloric cooling or microelectronics. The most-studied antiferroelectric is lead zirconate PbZrO3perovskite. However, the understanding of its switching mechanism is still incomplete. In this work, we will first present our study on the sol-gel synthesis and characterisation of antiferroelectric polycrystalline thin films of canonical lead zirconate PbZrO3. We will notably highlight the realisation of an in-plane switching of our antiferroelectric samples grown on transparent substrates, as well as the optical observation of this switching through birefringence changes. On a more fundamental side, the oldest and best-known model of antiferroelectricity was defined by Kittel in 1951. No real unidimensional Kittel-like model material has, to our knowledge, been identified yet. We will detail our spectroscopic study of the lattice dynamics of francisite Cu3Bi(SeO3)2O2Cl which combines several inelastic scattering experiments. We will then discuss how this study proves that francisite is, to our knowledge, the best candidate of a material displaying a displacive antiferroelectric phase transition.

The present work aims at investigating the structural properties of ultrathin rare-earth nickelate films by Raman Spectroscopy. Two remarkable cases are studied: LaNiO3 deposited epitaxially on LaAlO3, which shows a metal-to-insulator (MIT) transition but only in the ultrathin film regime, and NdNiO3 deposited epitaxially on NdGaO3 showing an upward shift of its MIT temperature by 130 K but only when deposited along the [111]pc direction of the substrate. The extremely small size of the films and overlap of the film and substrate signatures represent an experimental challenge and require the development of ingenious measurement and analysis strategies. To overcome these limitations, we propose the creation of a multidimensional dataset through depth profile acquisitions, in combination with multivariate analysis tools that were employed to extract the signature of the films. Different analysis strategies were used in both cases to adapt to the specificities of the respective samples. For the LNO films deposited along the [001]pc orientation of LAO, Raman depth profile measurements in combination with a Principal Component Analysis (PCA) allowed us to dissociate the signals from the film and the substrate. The evolution of the LNO peaks does not suggest any phase transition, thus, suggesting that a mechanism unrelated to the MIT of other nickelates is triggering the insulating state. This was further validated by ab initio calculations and TEM imaging. All acquired data point towards the following: as LNO becomes very thin, the surface layer (≈ 2pc u.c.), which is the most rigid part of the structure, imposes its structural and insulating characteristic. In the ultrathin regime this continues to a point where the surface of the film alters the interfacial unit cells of the substrate. For the NNO films deposited along the [111]pc orientation of NGO, depth profile measurements in combination with a Non-negative Matrix Factorisation (NMF) allowed us to dissociate the si

The context of use has been highlighted for a long time as being a key factor impacting User Experience (UX). Yet current UX evaluation tools, especially questionnaires, rarely encompass an explicit investigation of the context. With the ever-growing trend for mobile products and ubiquitous computing, the absence of a dedicated measurement tool becomes critical. Based on a review of relevant literature and a fine-grained categorization of contextual factors, we developed the UX Context Scale (UXCS), a 30-items instrument allowing for a measure of context properties, as perceived by the user. We report on the development of the scale and present a first validation study (N = 137). A principal component analysis on the subjective items reveals a 6-components structure: Physical Context, Social Context, Internal Context, Perceived Resources, Task Context, and Temporal Context. Reliability of each subscale is high and further analyses confirm the relevance of this tool for UX evaluation.

Polymer composites with high thermal conductivity are in strong demand for efficient thermal management in many modern applications such as electronics, batteries, aerospace structural materials, LED lightings, etc. Nanocarbon fillers have recently attracted a lot of interest due to their extremely high intrinsic thermal conductivity. Nevertheless, the effective thermal conductivity achieved with nanocarbon-polymer composites is below the expectations. In particular, at low fillers loading due to the large interfacial thermal resistance at the nanocarbon-polymer interface. Covalent functionalization of nanocarbons has been suggested to reduce the interfacial thermal resistance in nanocarbon-polymer composites. However, large scale covalent functionalization of nanocarbons is usually achieved with harsh oxidizing conditions, causing a dramatic decrease of the intrinsic thermal conductivity of the nanocarbon fillers. In this thesis, we developed and optimized a non-disruptive covalent functionalization for graphene nanoplatelets (GNP), based on nitrene chemistry. We achieved unprecedented functionalization yields. The fillers functionalized by nitrene chemistry produced a significant thermal conductivity enhancement (TCE) compared to pristine and oxidized fillers. However, increasing the chain length or introducing heteroatoms in the functional chain afforded reduced performances. In parallel, we developed an innovative combination of SEM and µCT analyses to afford an unprecedented description of nanocarbon-polymer composites. This allowed us to elucidate the contradictory results, reported in the literature, on the influence of the aggregation level and the geometrical parameters of the fillers on the TCE. In this thesis we propose a novel and detailed description of the parameters responsible of TCE in GNP-epoxy composites. Moreover, we demonstrate that covalent functionalization of GNP by nitrene chemistry reduces the interfacial thermal resistance in epoxy composi

Lead zirconate titanate (PZT) thin films are a popular choice for piezoelectric devices such as microelectromechanical systems, micro-pumps, micro-mirrors or energy harvesters. Various fabrication techniques exist for the deposition of PZT in the form of thin films. Physical vapor deposition (PVD) methods are particularly cost-intensive, as they require vacuum conditions and expensive infrastructure. Fabrication costs can be decreased by the use of chemical solution deposition (CSD), where the metal precursors are dispersed in a solvent medium and coated onto a substrate. Thermal treatments convert the liquid precursor into a functional solid film. Spin coating is a conventional coating technique allowing for the deposition of homogeneous layers over large-area substrates. However, it is inherently wasteful, as most of the precursor material is spun off the substrate in the coating process. In addition, as spin coating results in complete coverage of the substrate, layer patterning requires lithography, which adds up extra steps and costs to the overall process. Inkjet printing is an additive manufacturing technique that has the potential to address both of these issues, thus further decreasing manufacturing costs and the associated ecological footprint. The working principle of inkjet printing can be described as the deposition of individual ink droplets at digitally determined locations on the substrate surface, which then merge into a continuous film. Inkjet printing is compatible with CSD processing of PZT thin films, as demonstrated by the previous works in the field. However, the adaptation of standard CSD processing for inkjet printing comes with several challenges, which have to be considered to obtain state-of-the-art functional PZT layers. In the present work, we explore several issues related to the processing of PZT thin films by inkjet printing and we provide possible solutions to address them, in a way that had not been described yet by the state of th

Following the work of Pierre Bourdieu and Gustav Schmoller before him, the multipolarity of the middle classes between higher and lower, and between cultural and economic capitals is well acknowledged. This old vision is useful to understand the “middle classes adrift” of the last 20 years in France and Continental Europe. The expansion of the “new wage earner middle class” of the 1960s to 1990s is now an old dream of the welfare state expansion of Western societies, and the European social structure now faces a trend of “repatrimonialization”, meaning a U-turn towards a decline in the value of mid-qualified work and an expansion of the return to the inheritance of family assets. This paper addresses three main points. First, a new description of repatrimonialization is useful in the specific European context of middle-class societies. We need a redefinition of the system of middle classes (plural) in the context of the construction and decline of strong welfare states. Second, there are three ruptures in the social trends of the ‘wage earner society’ of the 1960s to 1990s. In this period, economic growth, social homogenization and social protection were major contextual elements of the expansion of ‘the new middle class,’ based on educational meritocracy, the valorization of credentialed skills, and the expansion of the average wage compared to housing and capital assets (‘depatrimonialization’). After the 1990s, the rupture and reversal of these trends, with ‘stagnation’, ‘new inequalities’ and ‘social uncertainty’ as new trends, generated a backlash in the “middle class society”. Third, I analyze the demographic and social consequences of these new trends in terms of the shrinking of the middle classes in a context where the inheritance of assets and resources changed the previous equilibrium. Finally, I highlight the importance of addressing the problem of social stability when large strata of the middle class have less interest in the maintenance of the social

Predictive analysis of poroelastic materials typically require expensive and time-consuming multiscale and multiphysics approaches, which demand either several simplifications or costly experimental tests for model parameter identification. This problem motivates us to develop a more efficient approach to address complex problems with an acceptable computational cost. In particular, we employ artificial neural network (ANN) for reliable and fast computation of poroelastic model parameters. Based on the strong-form governing equations for the poroelastic problem derived from asymptotic homogenisation, the weighted residuals formulation of the cell problem is obtained. Approximate solution of the resulting linear variational boundary value problem is achieved by means of the finite element method. The advantages and downsides of macroscale properties identification via asymptotic homogenisation and the application of ANN to overcome parameter characterisation challenges caused by the costly solution of cell problems are presented. Numerical examples, in this study, include spatially dependent porosity and solid matrix Poisson ratio for a generic model problem, application in tumour modelling, and utilisation in soil mechanics context which demonstrate the feasibility of the presented framework.

We introduce a hybrid "Modified Genetic Algorithm-Multilevel Stochastic Gradient Descent" (MGA-MSGD) training algorithm that considerably improves accuracy and efficiency of solving 3D mechanical problems described, in strong-form, by PDEs via ANNs (Artificial Neural Networks). This presented approach allows the selection of a number of locations of interest at which the state variables are expected to fulfil the governing equations associated with a physical problem. Unlike classical PDE approximation methods such as finite differences or the finite element method, there is no need to establish and reconstruct the physical field quantity throughout the computational domain in order to predict the mechanical response at specific locations of interest. The basic idea of MGA-MSGD is the manipulation of the learnable parameters’ components responsible for the error explosion so that we can train the network with relatively larger learning rates which avoids trapping in local minima. The proposed training approach is less sensitive to the learning rate value, training points density and distribution, and the random initial parameters. The distance function to minimise is where we introduce the PDEs including any physical laws and conditions (so-called, Physics Informed ANN). The Genetic algorithm is modified to be suitable for this type of ANN in which a Coarse-level Stochastic Gradient Descent (CSGD) is exploited to make the decision of the offspring qualification. Employing the presented approach, a considerable improvement in both accuracy and efficiency, compared with standard training algorithms such classical SGD and Adam optimiser, is observed. The local displacement accuracy is studied and ensured by introducing the results of Finite Element Method (FEM) at sufficiently fine mesh as the reference displacements. A slightly more complex problem is solved ensuring the feasibility of the methodology

The developmental origin of human adults’ right hemispheric dominance in response to face stimuli remains unclear, in particular because young infants’ right hemispheric advantage in face-selective response is no longer present in preschool children, before written language acquisition. Here we used fast periodic visual stimulation (FPVS) with scalp electroencephalography (EEG) to test 52 preschool children (5.5 years old) at two different levels of face discrimination: discrimination of faces against objects, measuring face-selectivity, or discrimination between individual faces. While the contrast between faces and nonface objects elicits strictly bilateral occipital responses in children, strengthening previous observations, discrimination of individual faces in the same children reveals a strong right hemispheric lateralization over the occipitotemporal cortex. Picture-plane inversion of the face stimuli significantly decreases the individual discrimination response, although to a much smaller extent than in older children and adults tested with the same paradigm. However, there is only a nonsignificant trend for a decrease in right hemispheric lateralization with inversion. There is no relationship between the right hemispheric lateralization in individual face discrimination and preschool levels of readings abilities. The observed difference in the right hemispheric lateralization obtained in the same population of children with two different paradigms measuring neural responses to faces indicates that the level of visual discrimination is a key factor to consider when making inferences about the development of hemispheric lateralization of face perception in the human brain.

Mesoporous TiO2 films with enhanced photocatalytic activity in both UV and visible wavelength ranges were developed through a non-conventional atomic layer deposition (ALD) process at room temperature. Deposition at such a low temperature promotes the accumulation of by-products in the amorphous TiO2 films, caused by the incomplete hydrolysis of the TiCl4 precursor. The additional thermal annealing induces the fast recrystallisation of amorphous films, as well as an in situ acidic treatment of TiO2. The interplay between the deposition parameters, such as purge time, the amount of structural defects introduced and the enhancement of the photocatalytic properties from different mesoporous films clearly shows that our easily upscalable non-conventional ALD process is of great industrial interest for environmental remediation and other photocatalytic applications, such as hydrogen production.

The preparation of ZnO thin films with controlled electrical resistivity and optical properties is often challenged by the presence of defects, such as oxygen vacancies or interstitial zinc. Here, we investigate the material properties of ZnO polycrystalline thin films prepared by thermal Atomic Layer Deposition (ALD) with the presence of molecular oxygen pulsing during the growth. By means of structural, electrical and optical characterizations, we identify key growth parameters of this unusual ALD process. Unexpectedly, the influence of oxygen molecules on the crystallography, microstructure and morphology of ZnO films is significant from hundred-nanometers to micrometer thick film. The electrical resistivity of the films grown with oxygen gas shows a dramatic increase from 3 to 4 orders of magnitude. Additionally, photoluminescence measurements reveal that deep-level emissions caused by defects located deep in the band gap can be reduced by applying an adequate pulsing of oxygen gas during the process. Finally, we conclude with a discussion about the degree of consistency between the chemical composition, the inner strain and the optical and electrical properties of the films obtained with the different thermodynamic parameters of growth. Several hypotheses are discussed in order to understand the dominance of (002) orientation in the presence of oxygen during the ALD growth process.

Low-temperature atmospheric pressure plasma was demonstrated to have an ability to generate different reactive oxygen and nitrogen species (RONS), showing wide biological actions. Within this study, mesoporous silica nanoparticles (NPs) and FexOy/NPs catalysts were produced and embedded in the polysaccharide matrix of chitosan/curdlan/hydroxyapatite biomaterial. Then, basic physicochemical and structural characterization of the NPs and biomaterials was performed. The primary aim of this work was to evaluate the impact of the combined action of cold nitrogen plasma and the materials produced on proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (ADSCs), which were seeded onto the bone scaffolds containing NPs or FexOy/NPs catalysts. Incorporation of catalysts into the structure of the biomaterial was expected to enhance the formation of plasma-induced RONS, thereby improving stem cell behavior. The results obtained clearly demonstrated that short-time (16s) exposure of ADSCs to nitrogen plasma accelerated proliferation of cells grown on the biomaterial containing FexOy/NPs catalysts and increased osteocalcin production by the cells cultured on the scaffold containing pure NPs. Plasma activation of FexOy/NPs-loaded biomaterial resulted in the formation of appropriate amounts of oxygen-based reactive species that had positive impact on stem cell proliferation and at the same time did not negatively affect their osteogenic differentiation. Therefore, plasma-activated FexOy/NPs-loaded biomaterial is characterized by improved biocompatibility and has great clinical potential to be used in regenerative medicine applications to improve bone healing process., Peer Reviewed, Postprint (published version)

The “Macedonia” name issue has been a constant point of contention between Greece and the newly re-named Republic of North Macedonia, since the breakup of Yugoslavia. With the origins of the dispute stretching back to the Second World War, the “Prespa Agreement,” signed between the two Balkan neighbors in June 2018 (coming into force in February 2019) is hoped to be a new beginning in interstate relations in the Balkans. Through Prime Ministers Tspiras and Zeav have adopted warm facades in front of the cameras, significant opposition to the agreement domestically and abroad highlights the transnational / international legacy and implications of this dispute. In this lecture, Dr, Spero Paravantes will examine the history of the dispute over the name “Macedonia.” He will then explain the Prespa Agreement, some of the controversies surrounding it, and he will discuss the role played in the dispute (and in the agreement) by foreign diplomats. He will concluded with an assessment of the domestic and international implications of the Former Yugoslav Republic of Macedonia (FYROM), becoming the Republic of North Macedonia. (Link: http://events.berkeley.edu/index.php/calendar/sn/ies.html?event_ID=124978&date=2019-04-29&filter=Target/Open%20To%20Audiences&filtersel=) (Summary: https://ies.berkeley.edu/sites/default/files/shared/docs/newsletters/IES%20Spring%202019%20News%20final.pdf)

BaZrO3 is a perovskite that remains in the simple cubic phase at all temperatures, hence with no first-order Raman-active phonon mode allowed by symmetry. Yet, it exhibits an intense Raman spectrum with sharp and well-defined features. Here, we report the evolution of the Raman spectrum of BaZrO3 single crystals in a broad temperature range (4-1200 K) and discuss its origin with the support of detailed first-principle calculations of the lattice dynamics. Phonon calculations are performed not only for the cubic phase of BaZrO3, but also for the low-symmetry phases with octahedra tilts that have been suspected to exist at the nanoscale. We show that the Raman spectrum shows no direct evidence for these nanodomains, but can instead be explained by classical second-order Raman scattering. We provide an assignment of the dominant features to phonon mode combinations. In particular, we show that the high frequency range of the spectrum is dominated by overtones and shows an image of the phonon density of states corresponding to the stretching modes of the oxygen octahedra.

This article summarizes the legal, historical and political developments in regards to the issue of WWII reparations. It suggests that due to the separation between the historical and legal fields which have examined the issue of WWII reparations, no generally accepted notion about their status exists either in the historical, legal or political spheres. It is this lack of clarity that has greatly contributed to this issue remaining unresolved thus far. This paper’s originality lies in its combination of diverse and original sources, both primary and secondary, in addition to referring to the text of the treaties in question to bring the debate on WWII reparations into a single narrative and addressing some of the shortcomings in other studies. It is also original because no previous studies on WWII reparations have addressed the role their ‘settlement’ played in the early European Integration process. In conclusion, the paper responds to arguments stating that the issue is closed, and questions whether or not the US and USSR did in fact have the right to suspend the rights of their allies to claim reparations from Germany upon re-unification.

Light-induced phenomena in ferroelectric materials have been exploited for decades for optoelectronic applications. Homogeneous illumination of a non-centrosymmetric ferroelectric material creates anomalously high voltages exceeding a value which is usually limited by its band gap. This phenomenon is called the bulk-photovoltaic effect (BPVE). Lithium niobate is a prototypical material for BPVE. The only limiting factor in lithium niobate is its low photo-current values, which can be improved by doping the crystal with donor metals. This study focuses primarily on light induced processes in mono-domain lithium niobate single crystals doped with transition metal ions, particularly the influence of stress on the BPVE. The effect of stress on BPVE is termed the piezo-photovoltaic effect (PPVE). This thesis report is framed to systemically introduce topics which cause, influence and aid in understanding the PPVE. Topics such as the symmetry in crystals, their physical properties, the intrinsic bulk photovoltaic effect (BPVE) are introduced and the structure, defects, light-induced charge transport in donor doped lithium niobate and the reason behind the appearance of BPVE are discussed in this report. The techniques and experimental arrangements used in this work are detailed in this thesis. A direct evidence of BPVE and the influence of stress is shown in the results. Transition metal doped lithium niobate crystals are oriented via x-ray diffraction (XRD) and a basic chemical characterization is undertaken using secondary ion mass spectrometry (SIMS) to identify dopant elements. Absorption spectroscopy in the UV/VIS/NIR range revealed windows in the spectra indicating photo-excitation of the donor doped ions. The absorption lines show that a shift in the fundamental band-edge occurs in lithium niobate for different dopant elements. Electron paramagnetic resonance (EPR) spectrometry is performed on the samples to confirm the location of the dopant ion in the crystal mat